Why must biologic therapy continue in ankylosing spondylitis after MRI shows complete resolution of sacroiliac joint bone marrow edema?

The MRI resolution of sacroiliac joint bone marrow edema is one of the most consequential misconceptions in AS care. A patient who reads an MRI report stating 'no evidence of active sacroiliitis' — or whose nurse explains that the MRI is 'normal' — naturally infers that the disease has resolved and the medication is no longer needed. This inference is mechanistically incorrect in a specific and important way. Bone marrow edema on MRI STIR sequences in AS represents acute inflammatory infiltration at the sacroiliac joint entheseal-bone interface: neutrophils, macrophages, and lymphocytes recruited by TNF-alpha, IL-17A, and IL-23/IL-12-driven Th17 cell activity at the SI joint fibrocartilaginous entheseal complex, with the bone marrow edema reflecting the inflammatory mediators and fluid accumulation in the subchondral marrow space adjacent to the inflamed enthesis. TNF-alpha inhibitors — adalimumab, etanercept, certolizumab pegol, golimumab — suppress this acute inflammatory signal by preventing TNF-alpha from binding its TNFR1 and TNFR2 receptors, thereby blocking NF-kB activation and downstream inflammatory cytokine production. The result is exactly the MRI resolution we see in a responding patient: bone marrow edema disappears because the acute inflammatory infiltration driving it is suppressed. But structural damage in AS — sacroiliac joint sclerosis, erosion, and ankylosis, and spinal syndesmophyte formation — progresses through a mechanistically separate pathway from the acute TNF-alpha-driven inflammation that MRI detects. BMP-2 and BMP-4, produced at entheseal sites in response to prior mechanical stress and prior inflammatory episodes, activate SMAD1/5/8 signaling in entheseal fibroblasts and periosteal progenitor cells, driving their differentiation into chondrocytes via SOX9 upregulation. These chondrocytes form the fibrocartilaginous intermediate of endochondral ossification at entheseal transition zones — the process that eventually mineralizes and calcifies into the bony bar of a syndesmophyte. Wnt-beta-catenin pathway activation through Wnt3a, Wnt7a, and Wnt10b ligands produced by macrophages and activated fibroblasts at previously inflamed entheseal sites adds a parallel intramembranous bone formation pathway: beta-catenin nuclear accumulation drives RUNX2 and OSTEOCALCIN expression, promoting direct osteoblast differentiation. A complicating feature specific to AS is that TNF-alpha, in addition to driving inflammation, simultaneously induces DKK1 (Dickkopf-1), the endogenous inhibitor of the Wnt pathway. When TNF-alpha is high in active untreated AS, DKK1 is upregulated, Wnt signaling is partially suppressed, and new bone formation may paradoxically be lower in the most inflamed patients. When TNF-alpha inhibitor is given and TNF-alpha is suppressed, DKK1 production falls, Wnt signaling is disinhibited, and entheseal osteogenesis can proceed — this is one reason TNF inhibitors, despite controlling inflammation well, do not fully arrest radiographic progression in many AS patients. When TNF inhibitor is stopped: TNF-alpha returns to pre-treatment levels within four to six weeks (adalimumab t½ ≈14 days). Acute inflammation at the SI joint resumes, bone marrow edema returns on MRI. The BMP-Wnt osteogenic process that was modestly suppressed by anti-inflammatory mechanisms is now driven by renewed full TNF-alpha-mediated inflammatory activation. Structural progression accelerates. The annual lateral cervical and lumbar spine x-ray detects syndesmophyte formation that MRI and symptoms both miss. ASSERT and ATLAS extension trials show that approximately 40 percent of patients who stopped TNF inhibitor after achieving clinical remission relapsed within twelve weeks. Radiographic data in AS extension trials (van der Heijde et al. for adalimumab, MEASURE trials for secukinumab) consistently show mSASSS progression continuing even during biologic therapy in the broad population, and accelerating upon drug withdrawal. Spanish frame: 'La resonancia magnética muestra la inflamación aguda — el edema en los huesos alrededor de la articulación sacroilíaca. Cuando el adalimumab bloquea el TNF-alfa, esa inflamación aguda desaparece — exactamente como la resonancia muestra. Eso es la buena noticia: el medicamento está funcionando. El problema es que hay un proceso diferente en esa misma articulación que la resonancia no mide bien: la formación de hueso nuevo en los bordes del hueso, la calcificación de los ligamentos, la fusión progresiva. Ese proceso tiene su propio mecanismo — las proteínas morfogenéticas óseas y la vía Wnt — que es parcialmente independiente de la señal inflamatoria aguda que la resonancia detecta. Cuando el adalimumab se para, el TNF-alfa regresa en cuatro a seis semanas, la inflamación aguda vuelve, y ese proceso de formación de hueso nuevo se acelera de nuevo. La resonancia normal es la señal de que el medicamento está funcionando. No es la señal de que se puede parar el medicamento.' (The MRI shows acute inflammation — the edema in the bones around the sacroiliac joint. When adalimumab blocks TNF-alpha, that acute inflammation disappears — exactly as the MRI shows. That is the good news: the medication is working. The problem is there is a different process in that same joint that the MRI does not measure well: new bone formation at the bone edges, calcification of ligaments, progressive fusion. That process has its own mechanism — bone morphogenetic proteins and the Wnt pathway — that is partially independent of the acute inflammatory signal the MRI detects. When adalimumab is stopped, TNF-alpha returns in four to six weeks, the acute inflammation returns, and that new bone formation process accelerates again. The normal MRI is the sign that the medication is working. It is not the sign that the medication can be stopped.)

How do AS clinic nurses explain that physical therapy and daily exercises remain essential even when biologic therapy controls pain in Spanish?

Patients with longstanding ankylosing spondylitis who achieve dramatic pain relief on a TNF inhibitor or IL-17 inhibitor commonly conclude that physical therapy was for pain management and is no longer needed once the biologic controls the pain. For patients with partial ankylosis — partial or complete syndesmophyte bridging, SI joint fusion, reduced chest expansion, elevated tragus-to-wall distance — this conclusion is a consequential error because the structural damage that is already present is permanent and irreversible, and the only mechanism preventing it from spreading further into the remaining mobile spinal segments is daily mechanical loading through structured extension exercises. The fused sacroiliac joints and the established syndesmophytes do not improve with any medication. What medications prevent is the rate of new syndesmophyte formation and the rate of spread into segments that are not yet fused. But within the remaining mobile segments, the entheseal fibroblasts at the vertebral corner insertions, facet joint capsules, and posterior spinal ligament insertions exist in a state of chronic low-level Wnt-BMP osteogenic activity established by prior inflammatory episodes. Without daily mechanical loading, this osteogenic state progresses unchecked. Daily spinal extension exercises — prone extension, lumbar extension in standing, cervical retraction, thoracic expansion exercises — generate cyclical tensile strain at the posterior spinal entheseal insertions. This mechanical strain activates PIEZO1 and PIEZO2 mechanosensing ion channels in entheseal fibroblasts, driving calcium influx that activates calmodulin-kinase II and endothelial nitric oxide synthase (eNOS/NOS3). Nitric oxide produced by NOS3 activates soluble guanylyl cyclase (sGC), elevating cGMP, which activates protein kinase G1 (PKG1). PKG1 phosphorylates and activates GSK3-beta, the kinase in the Wnt destruction complex that phosphorylates beta-catenin at serine 33, serine 37, and threonine 41, targeting it for ubiquitin-mediated degradation. Mechanical loading also increases sclerostin production from osteocytes embedded in loaded bone adjacent to entheseal insertions. Sclerostin binds LRP5 and LRP6 coreceptors on entheseal fibroblasts and blocks Wnt ligand engagement, providing a second load-induced suppression of Wnt-driven osteogenesis. Without daily loading, both these mechanical Wnt-suppression pathways are absent or diminished: PKG1-mediated GSK3-beta activation decreases, beta-catenin degradation slows, and Wnt-driven osteogenic gene transcription proceeds at a higher basal rate. Sclerostin production in osteocytes falls without mechanical stimulation, removing the LRP5/6-level Wnt blockade. The ASAS-EULAR management recommendations explicitly state that regular exercise is essential for AS patients at all stages, including those on biologic therapy, and that individually tailored physical therapy should be continued regardless of pharmacological disease control. Published cohort studies (Hsieh et al. 2015; Dagfinrud et al. Cochrane review) demonstrate that AS patients on stable TNF inhibitor therapy who discontinue regular exercise have measurable BASMI worsening — typically 0.5 to 0.9 BASMI units over twelve to eighteen months — even while maintaining full biologic treatment, while those who continue daily exercises maintain stable BASMI on the same biologic. Spanish frame: 'El certolizumab está controlando su dolor — eso es exactamente lo que esperábamos. Pero quiero explicarle algo importante sobre lo que la fisioterapia y los ejercicios hacen en su enfermedad que no tiene nada que ver con el dolor. Sus articulaciones sacroilíacas ya están fusionadas — eso no cambia con ningún medicamento. Los puentes de hueso que tiene en la columna lumbar tampoco van a desaparecer. Lo que sí podemos proteger son los segmentos de la columna que todavía tienen movilidad — la columna cervical, la parte de la columna torácica y lumbar que aún se puede mover. El ejercicio diario de extensión de la columna mantiene esa movilidad de una manera muy específica: el movimiento físico activa sensores mecánicos en las células del tejido ligamentoso y tendinoso de la columna, y esa activación mecánica produce señales que frenan la misma vía de formación de hueso que el TNF activa. Sin el movimiento diario, esa señal protectora desaparece, y el hueso sigue formándose silenciosamente en los segmentos que aún se pueden mover. El medicamento controla el dolor y reduce la inflamación. El ejercicio diario protege la movilidad que le queda. Necesita los dos.' (Certolizumab is controlling your pain — that is exactly what we expected. But I want to explain something important about what physical therapy and exercises do in your disease that has nothing to do with pain. Your sacroiliac joints are already fused — that does not change with any medication. The bone bridges you have in the lumbar spine will also not disappear. What we can protect are the spinal segments that still have mobility — the cervical spine, the part of the thoracic and lumbar spine that can still move. Daily spinal extension exercises maintain that mobility in a very specific way: the physical movement activates mechanical sensors in the ligamentous and tendinous tissue cells of the spine, and that mechanical activation produces signals that suppress the same bone-formation pathway that TNF activates. Without daily movement, that protective signal disappears, and bone continues to form silently in the segments that can still move. The medication controls pain and reduces inflammation. Daily exercise protects the mobility you have left. You need both.)

What is the difference between active inflammation and structural damage in ankylosing spondylitis, and why does this distinction matter for Spanish-speaking patients?

Ankylosing spondylitis produces two parallel and partially independent disease processes: acute inflammation and structural bone formation. Patients and clinicians who focus only on inflammation markers and MRI results risk missing the structural progression that produces the irreversible disability of AS. Acute inflammation in AS is driven by activated Th17 T cells at entheseal sites producing IL-17A, IL-23, and TNF-alpha. These cytokines drive neutrophil and macrophage recruitment to the sacroiliac joints and spinal entheses, produce the bone marrow edema visible on MRI STIR sequences, cause the inflammatory back pain with its nocturnal worsening and morning stiffness, and elevate acute-phase reactants like CRP and ESR. This acute inflammation is the target of NSAIDs, TNF inhibitors, and IL-17 inhibitors. When these medications work, the inflammation falls: MRI bone marrow edema resolves, CRP normalizes, ASDAS-CRP drops into the inactive range, and morning stiffness shortens. These are accurate and meaningful indicators of treatment success. Structural damage in AS is mechanistically separate: it is the new bone formation at entheseal sites that produces syndesmophytes (bony bars bridging adjacent vertebral bodies at the vertebral corners), SI joint ankylosis, facet joint fusion, and posterior ligamentous ossification. The process is driven by BMP-2/4-driven endochondral ossification through a fibrocartilaginous intermediate — entheseal fibroblasts differentiate to chondrocytes via SOX9 then to osteoblasts via RUNX2 in a process that mirrors growth plate ossification — and by Wnt-beta-catenin driven intramembranous osteoblast differentiation at periosteal surfaces. This structural process is not reflected well by MRI (which detects fluid but not mineralized bone), not reflected by CRP, and not reflected by subjective pain (the syndesmophyte itself does not hurt as it forms — pain comes from the inflammatory phase that preceded it). The two processes are 'decoupled' in established AS: a patient can be in complete clinical and imaging remission on biologic therapy while structural progression continues through BMP-Wnt pathways that were set in motion by prior inflammatory episodes. The lateral cervical and lumbar spine x-ray is the gold-standard tool for detecting structural progression because it directly images the mineralized bone: new vertebral corner erosions, sclerosis, and bridging syndesmophytes are visible on x-ray before producing symptoms and before being detectable on standard MRI protocols. Annual x-ray surveillance is recommended by ASAS-EULAR specifically because structural progression occurs even in clinically silent disease. Spanish frame: 'En la espondilitis anquilosante hay dos procesos que ocurren en la columna al mismo tiempo, y es importante entender la diferencia entre los dos. El primero es la inflamación activa — el dolor, la rigidez, el edema que se ve en la resonancia. Los medicamentos — el naproxeno, los biológicos — controlan esa inflamación. Cuando los medicamentos funcionan, la resonancia mejora, el CRP se normaliza, el dolor se reduce. Eso es una buena señal de que el tratamiento está funcionando. El segundo proceso es la formación de hueso nuevo en la columna — los puentes óseos que se llaman sindesmófitos que se van formando entre las vértebras. Ese proceso no duele mientras ocurre. No aparece en la resonancia en sus etapas tempranas. No cambia el CRP. Ocurre silenciosamente. La única forma de detectarlo es la radiografía anual de la columna. Y una vez formado el puente óseo, no se puede revertir. El tratamiento continuo — tanto con medicamentos como con ejercicio diario — reduce la velocidad de ese segundo proceso. Por eso el tratamiento no se para cuando el dolor mejora: el dolor mejorando es señal de que estamos controlando el primer proceso. El segundo proceso sigue activo en el fondo, y necesita control continuo.' (In ankylosing spondylitis there are two processes occurring in the spine simultaneously, and it is important to understand the difference between them. The first is active inflammation — the pain, the stiffness, the edema visible on MRI. Medications — naproxen, biologics — control that inflammation. When medications work, the MRI improves, CRP normalizes, pain reduces. That is a good sign that treatment is working. The second process is new bone formation in the spine — the bony bridges called syndesmophytes that form between vertebrae. That process does not hurt while it is occurring. It does not appear on MRI in its early stages. It does not change the CRP. It occurs silently. The only way to detect it is the annual spine x-ray. And once the bony bridge is formed, it cannot be reversed. Continuous treatment — both with medications and with daily exercise — reduces the speed of that second process. That is why treatment is not stopped when pain improves: pain improving is the sign that we are controlling the first process. The second process remains active in the background and needs continuous control.)

What are the key Spanish phrases for axial spondyloarthritis and ankylosing spondylitis clinic nurses explaining NSAID continuation, biologic continuation, and the essential role of exercise?

For explaining why NSAIDs must continue beyond pain relief: 'Los antiinflamatorios no esteroideos — naproxeno, celecoxib, ibuprofeno — hacen dos cosas en su enfermedad. Le quitan el dolor — eso es lo que usted siente. Y reducen una señal química en los sitios de inflamación de la columna que le diría a ciertas células que produzcan hueso nuevo. Cuando para el medicamento porque no le duele, para los dos efectos. El dolor regresa en días. El proceso de formación de hueso nuevo en la columna también regresa, pero sin síntomas — y es ese proceso el que lleva a la fusión de las vértebras con el tiempo.' (Non-steroidal anti-inflammatory drugs — naproxen, celecoxib, ibuprofen — do two things in your disease. They remove the pain — that is what you feel. And they reduce a chemical signal at the inflammation sites in the spine that would tell certain cells to produce new bone. When you stop the medication because you do not have pain, you stop both effects. Pain returns within days. The new bone formation process in the spine also returns, but without symptoms — and it is that process that leads to vertebral fusion over time.) For explaining MRI remission and continued biologic need: 'La resonancia magnética normal es exactamente lo que buscamos cuando iniciamos el tratamiento biológico. Eso quiere decir que el medicamento está haciendo su trabajo. Lo que quiero que entienda es por qué ese resultado no significa que el medicamento ya no es necesario. El edema que antes se veía en la resonancia era la inflamación aguda que el adalimumab estaba bloqueando. Cuando usted para el adalimumab, esa inflamación regresa en semanas. Y con ella regresa la señal para que el hueso siga formándose en la columna. La resonancia normal es la razón para continuar el medicamento — es la señal de que está funcionando.' (The normal MRI is exactly what we seek when we start biologic treatment. That means the medication is doing its job. What I want you to understand is why that result does not mean the medication is no longer needed. The edema that was previously visible on MRI was the acute inflammation that adalimumab was blocking. When you stop adalimumab, that inflammation returns within weeks. And with it returns the signal for bone to continue forming in the spine. The normal MRI is the reason to continue the medication — it is the sign that it is working.) For explaining exercise in AS regardless of pain level: 'El ejercicio diario de extensión de la columna — los ejercicios que le enseñaron en fisioterapia — no son para el dolor. Son para mantener la movilidad de los segmentos de la columna que aún pueden moverse. El movimiento físico activa señales en los tejidos de la columna que frena la formación de hueso nuevo en esos segmentos. Sin el movimiento diario, esa señal protectora desaparece y el hueso avanza silenciosamente. El biológico reduce la inflamación. El ejercicio protege la movilidad. Los dos son necesarios al mismo tiempo.' (Daily spinal extension exercises — the exercises physical therapy taught you — are not for pain. They are to maintain the mobility of the spinal segments that can still move. Physical movement activates signals in spinal tissues that suppress new bone formation in those segments. Without daily movement, that protective signal disappears and bone advances silently. The biologic reduces inflammation. Exercise protects mobility. Both are needed at the same time.) For explaining irreversibility of ankylosing spondylitis structural damage: 'Los cambios que ya hay en sus huesos — la fusión de la articulación sacroilíaca, los puentes óseos en la columna lumbar — son permanentes. No hay medicamento ni tratamiento que los revierta. Lo que sí podemos hacer es prevenir que esos cambios avancen a los segmentos de la columna que aún tienen movilidad. Para eso necesitamos el medicamento para controlar la inflamación y los ejercicios diarios para mantener la movilidad mecánica. Cuando usted para los ejercicios porque no le duele, retira uno de los dos mecanismos de protección.' (The changes already present in your bones — the sacroiliac joint fusion, the bony bridges in the lumbar spine — are permanent. There is no medication or treatment that reverses them. What we can do is prevent those changes from advancing to the spinal segments that still have mobility. For that we need the medication to control inflammation and daily exercises to maintain mechanical mobility. When you stop exercises because you do not hurt, you withdraw one of the two protective mechanisms.) For explaining the role of annual x-ray surveillance: 'La radiografía anual de la columna no es para confirmar que le duele. Es para detectar la formación de hueso nuevo antes de que cause síntomas o que esté tan avanzada que no podamos hacer nada. Los puentes óseos entre las vértebras se forman silenciosamente durante meses o años antes de producir rigidez notoria. La radiografía los detecta en etapa temprana. Si los detectamos temprano y ajustamos el tratamiento — incluyendo la consistencia del ejercicio diario — podemos ralentizar el proceso significativamente.' (The annual spine x-ray is not to confirm that you hurt. It is to detect new bone formation before it causes symptoms or becomes so advanced that nothing can be done. Bony bridges between vertebrae form silently over months or years before producing noticeable rigidity. The x-ray detects them at an early stage. If we detect them early and adjust treatment — including the consistency of daily exercise — we can slow the process significantly.)

November 3, 2026 · Rheumatology, Axial Spondyloarthritis, Ankylosing Spondylitis

Spanish for axial spondyloarthritis and ankylosing spondylitis clinic nurses — the patient who stopped naproxen when back pain improved not knowing NSAIDs suppress PGE2-driven entheseal osteogenic signaling independent of analgesia; the patient who stopped adalimumab when MRI showed no active sacroiliac joint bone marrow edema not knowing BMP-driven structural bone formation continues decoupled from the acute TNF-alpha signal; and the patient who stopped physical therapy when biologic controlled his pain not knowing daily spinal extension exercises are the only remaining counterregulator of progressive ossification in the still-mobile segments of a partially ankylosed spine

Three conversations for axial spondyloarthritis and ankylosing spondylitis clinic nurses: Eduardo Martínez-Reyes, 34, Austin, who stopped naproxen when pain improved not knowing NSAIDs have two independent effects in AS and pain relief does not mean structural protection is no longer needed; Valentina Ríos-Espinoza, 29, San Antonio, who stopped adalimumab when MRI showed no active sacroiliitis not knowing biologic-induced MRI resolution is evidence the drug is working, not evidence the disease has resolved; and Roberto Cisneros-Torres, 51, El Paso, who stopped physical therapy when certolizumab controlled his pain not knowing exercise-induced mechanical loading is the only mechanism counteracting entheseal osteogenesis in the segments his ankylosis has not yet reached.

Axial spondyloarthritis and ankylosing spondylitis present the clinic nurse with an adherence landscape structured around three categories of misunderstanding that differ fundamentally from each other but share a common feature: the patient is using a real, accurate observation to reach a mechanistically incorrect conclusion about whether treatment is still needed. The pain improves — therefore the pain reliever is no longer needed. The MRI normalizes — therefore the disease has gone away. The pain is controlled — therefore the exercises, which the patient understood as pain-management exercises, can stop. Each observation is real. Each conclusion from that observation misses the second mechanism, the hidden process, the thing that will quietly progress while the patient feels well.

Axial spondyloarthritis is a seronegative inflammatory arthropathy driven by dysregulated Th17 immunity at entheseal sites — the insertions of ligaments, tendons, and joint capsules onto bone. In the spine, these entheseal sites at the vertebral corners and the sacroiliac joint fibrocartilaginous complex are the sites of both the acute inflammation that produces pain and the new bone formation that eventually produces syndesmophytes and ankylosis. The two processes are related but partially decoupled: acute inflammation activates the osteogenic cascade, but once the osteogenic cascade is established at an entheseal site, it can continue at a reduced but non-zero rate even when inflammation is suppressed by medication. This decoupling is the core conceptual gap in AS patient education, and it is a gap that produces measurable, irreversible consequences when it remains unclosed.

Three patients, three structurally distinct errors, three conversations that each address a different layer of this decoupling: the NSAID layer, the biologic layer, and the exercise layer.

Scenario 1: Eduardo Martínez-Reyes — 34 years old, Austin, Texas

Eduardo Martínez-Reyes was a thirty-four-year-old construction project manager in Austin who had been experiencing low back pain for seven years — since age twenty-seven — without a diagnosis that explained it. He had seen a chiropractor for two years, a sports medicine physician who diagnosed lumbar muscle strain, and an orthopedic surgeon who found no surgical pathology. The pain was different from mechanical back pain in ways he had mentioned to each provider: it was worse in the second half of the night, waking him between three and five in the morning; it was worst in the morning and improved with physical activity; it improved on days he worked physically but returned when he rested over a long weekend; it had a deep aching quality in the sacral and buttock region, alternating sides. His older brother had psoriasis.

A rheumatology referral finally came through a primary care physician who had attended a continuing education session on inflammatory back pain. The rheumatology evaluation confirmed non-radiographic axial spondyloarthritis: his ASDAS-CRP was two point nine (active disease), CRP was fourteen milligrams per liter, morning stiffness fifty-five minutes, and his HLA-B*27 was positive. Pelvic x-ray was normal — no sacroiliac joint changes visible on plain film, which is typical of nr-axSpA by definition. MRI of the sacroiliac joints showed bilateral bone marrow edema on STIR sequences at both SI joints — a SPARCC score of eight, confirming active sacroiliitis that had not yet produced visible bone changes on x-ray. The rheumatologist prescribed naproxen five hundred milligrams twice daily with omeprazole for gastric protection.

Eight weeks later, Eduardo felt dramatically better. His morning stiffness had shortened from fifty-five minutes to fifteen minutes. His nocturnal pain had nearly resolved — he was sleeping through the night. His back pain during the work day had dropped from seven of ten to two of ten. His ASDAS-CRP at the eight-week visit was one point eight — in the low disease activity range. He was pleased, and he had a reasonable question about why he needed to continue a medication when he was feeling fine.

He stopped naproxen on his own, between his eight-week visit and his scheduled three-month follow-up. When the axSpA clinic nurse, Alejandra Fuentes-Morales, called him at ten weeks for a routine check-in, he told her what he had decided.

“Me siento mucho mejor — casi normal. Me parece que el naproxeno hizo su trabajo y ya no lo necesito. Es un antiinflamatorio, y si la inflamación ya mejoró, para qué seguir tomándolo indefinidamente. Quiero ver qué pasa sin él.”

(I feel much better — almost normal. I think the naproxen did its job and I no longer need it. It is an anti-inflammatory, and if the inflammation has already improved, why continue taking it indefinitely. I want to see what happens without it.)

Nurse Fuentes-Morales recognized the reasoning immediately. Eduardo had made the correct observation — the naproxen had worked — but was inferring that its purpose was fulfilled. She needed to explain the two-effect architecture of NSAIDs in axSpA in a way that was clinically honest and practically actionable.

“Don Eduardo, tiene toda la razón en que el naproxeno hizo lo que esperábamos — le mejoró el dolor y la rigidez, y eso es exactamente lo que queríamos ver. Pero hay algo importante sobre el naproxeno en su enfermedad específica que quiero explicarle, porque la espondilitis axial no es como una lesión muscular donde el antiinflamatorio lo usa mientras le duele y luego para. Hay un segundo efecto del naproxeno que no tiene nada que ver con el dolor — y ese efecto también desaparece cuando para el medicamento.”

(Don Eduardo, you are entirely correct that naproxen did what we expected — it improved the pain and stiffness, and that is exactly what we wanted to see. But there is something important about naproxen in your specific disease that I want to explain, because axial spondylitis is not like a muscle injury where you use the anti-inflammatory while it hurts and then stop. There is a second effect of naproxen that has nothing to do with pain — and that effect also disappears when you stop the medication.)

Eduardo: “¿Un segundo efecto? ¿Qué efecto?”

“Le voy a explicar lo que ocurre en los sitios donde la inflamación de su enfermedad está activa — en los bordes de los huesos de la columna y en la articulación sacroilíaca. En esos lugares, la inflamación produce una sustancia química que se llama prostaglandina E2. Esa sustancia hace dos cosas al mismo tiempo. La primera: activa las fibras nerviosas que conducen el dolor — esa es la razón por la que siente el dolor nocturno y la rigidez matutina. El naproxeno bloquea la enzima que produce esa prostaglandina — entonces menos prostaglandina, menos activación del dolor. Eso es lo que usted notó que mejoró.”

(I am going to explain what happens at the sites where the inflammation of your disease is active — at the edges of the spinal bones and at the sacroiliac joint. At those places, the inflammation produces a chemical substance called prostaglandin E2. That substance does two things simultaneously. The first: it activates the nerve fibers that transmit pain — that is why you feel the nocturnal pain and morning stiffness. Naproxen blocks the enzyme that produces that prostaglandin — so less prostaglandin, less pain activation. That is what you noticed improved.)

“La segunda cosa que hace la prostaglandina E2 en la espondilitis axial: se une a receptores en las células del tejido que rodea los huesos de la columna — unas células que son precursoras del hueso — y activa una cascada molecular que empieza a hacer que esas células se conviertan en células que forman hueso nuevo. En la espondilitis axial, ese es el primer paso del proceso que lleva a que los vértebras de la columna se vayan fusionando con el tiempo — lo que llamamos sindesmófitos, que son puentes de hueso que se forman entre las vértebras adyacentes. El naproxeno bloquea la producción de esa prostaglandina — y al hacerlo, también bloquea esa señal de formación de hueso nuevo, independientemente del dolor.”

(The second thing prostaglandin E2 does in axial spondylitis: it binds receptors on the cells of the tissue surrounding the spinal bones — cells that are precursors to bone — and activates a molecular cascade that begins to make those cells convert into cells that form new bone. In axial spondylitis, that is the first step of the process that leads to the spinal vertebrae progressively fusing over time — what we call syndesmophytes, which are bone bridges that form between adjacent vertebrae. Naproxen blocks the production of that prostaglandin — and in doing so, also blocks that new bone formation signal, independently of pain.)

Eduardo leaned forward slightly. He was a project manager — he was used to understanding system dependencies. “¿O sea que el naproxeno está haciendo dos cosas al mismo tiempo: quitarme el dolor Y evitando que se forme hueso nuevo en la columna?”

“Exactamente. Dos efectos, mismo medicamento. Cuando para el naproxeno porque no le duele, pierde los dos al mismo tiempo. El dolor regresa en días — usted lo va a notar cuando la prostaglandina se recupere. El efecto sobre la formación de hueso nuevo también se pierde, pero ese proceso es silencioso — no hay síntoma que le avise que está pasando. Por eso lo que los estudios clínicos en espondilitis axial muestran es que los pacientes que toman antiinflamatorios de manera continua — no solo cuando les duele — tienen significativamente menos progresión de esos puentes óseos en la columna comparado con los que los toman solo cuando hay dolor.”

(Exactly. Two effects, same medication. When you stop naproxen because you do not hurt, you lose both simultaneously. Pain returns within days — you will notice when prostaglandin recovers. The effect on new bone formation is also lost, but that process is silent — there is no symptom to warn you it is happening. That is why clinical studies in axial spondylitis show that patients who take anti-inflammatories continuously — not only when they hurt — have significantly less progression of those bone bridges in the spine compared to those who take them only when there is pain.)

Eduardo: “¿Eso significa que el naproxeno puede prevenir que la columna se me fusione?”

“Puede reducir la velocidad a la que ese proceso progresa — eso es lo que los datos clínicos muestran. No lo para completamente, pero lo enlentece significativamente comparado con no tomarlo. Y en su caso, que todavía no tiene cambios visibles en la radiografía de los huesos — solo en la resonancia magnética — es el momento más útil para el naproxeno continuo, porque la ventana en la que la protección estructural puede hacer la mayor diferencia es antes de que los cambios en la radiografía ya estén establecidos.”

(It can reduce the rate at which that process progresses — that is what the clinical data shows. It does not stop it completely, but it slows it significantly compared to not taking it. And in your case, where you do not yet have visible changes on the bone x-ray — only on MRI — this is the most useful moment for continuous naproxen, because the window in which structural protection can make the greatest difference is before x-ray changes are already established.)

Eduardo was quiet for a moment. He was a systematic thinker and had heard the logic clearly. “¿Y si el naproxeno continuo no es suficiente para controlar la enfermedad a largo plazo?”

“Si dentro de tres a seis meses la enfermedad sigue progresando — si su ASDAS sube, si los síntomas regresan de forma importante, o si la resonancia magnética de seguimiento muestra que la inflamación ha empeorado — hablaríamos con el reumátologo sobre el siguiente paso, que serían los biológicos. Esos bloquean directamente las sustancias inflamatorias con mayor potencia. Pero esa decisión se toma con datos reales, no adelantándola innecesariamente. Por ahora, el naproxeno continuo con el omeprazol para proteger el estómago es el tratamiento correcto para su estadio de la enfermedad.”

(If within three to six months the disease continues progressing — if your ASDAS rises, if symptoms return significantly, or if the follow-up MRI shows worsening inflammation — we would discuss with the rheumatologist the next step, which would be biologics. Those directly block the inflammatory substances with greater potency. But that decision is made with real data, not anticipated unnecessarily. For now, continuous naproxen with omeprazole to protect the stomach is the correct treatment for your stage of disease.)

Eduardo agreed to restart naproxen five hundred milligrams twice daily with omeprazole. He understood the two-effect architecture. At his three-month follow-up after restart, his ASDAS-CRP was one point seven, CRP six milligrams per liter, morning stiffness twenty minutes. At his twelve-month MRI, the SPARCC score had stabilized at three — not the zero of complete resolution, but measurably lower than the baseline of eight and not progressing. The rheumatologist added sulfasalazine as a peripheral enthesitis adjunct and continued naproxen. At eighteen months: lateral spine x-ray showed no new corner changes, no syndesmophyte formation. Eduardo continued naproxen.

Scenario 2: Valentina Ríos-Espinoza — 29 years old, San Antonio, Texas

Valentina Ríos-Espinoza was a twenty-nine-year-old emergency room nurse in San Antonio who had been diagnosed with ankylosing spondylitis at age twenty-two — seven years before the conversation that nearly ended her biologic therapy. She had received the modified New York criteria diagnosis early in her career, which she regarded, with the practical orientation of an ER nurse, as a condition to manage rather than a reason to change her life. She was HLA-B*27 positive. Her baseline pelvic x-ray had shown bilateral grade-four sacroiliitis — complete joint space loss at both SI joints with partial fusion. Her baseline lateral lumbar spine x-ray showed two vertebral corner scleroses at L4/L5 but no syndesmophytes bridging yet. Her baseline SPARCC MRI sacroiliac joint score was sixteen.

She had failed two years of naproxen five hundred milligrams twice daily (inadequate ASDAS response), then sulfasalazine two grams daily for eight months (gastrointestinal intolerance with persistent nausea and diarrhea at month three). Her rheumatologist had initiated adalimumab forty milligrams subcutaneously every two weeks three years before the conversation. The response had been excellent: within twelve weeks her ASDAS-CRP fell from three point four to one point two, her morning stiffness resolved from ninety minutes to under fifteen minutes, and her inflammatory back pain dropped from eight of ten to one of ten. She had continued adalimumab and been reliable about her injections, entering her ASAS-approved injection diary consistently.

At the thirty-six month visit, a surveillance MRI of the sacroiliac joints was ordered. The report read: “No evidence of active sacroiliitis. The previously noted bilateral bone marrow edema at the sacroiliac joints is no longer identified. Incidental bilateral SI joint sclerosis consistent with known prior radiographic changes. No new erosions.”

Valentina read her own report through the patient portal. She understood enough to parse the language. She had also been working in emergency medicine long enough to know that when a condition had “no evidence of active” changes, it was resolved. She messaged the AS clinic nurse, Carlos Domínguez-García, through the portal.

“Vi el resultado de mi resonancia — dice que no hay evidencia de sacroiliitis activa y que el edema que mostraba antes ya desapareció. Sigo tomando el adalimumab pero me pregunto si realmente lo necesito todavía. Si ya no hay inflamación activa en la articulación, ¿por qué seguir con el biológico? ¿Pueden hablar conmigo sobre esto en mi próxima cita?”

(I saw my MRI result — it says there is no evidence of active sacroiliitis and the edema that was showing before has disappeared. I am still taking adalimumab but I am wondering if I really still need it. If there is no longer active inflammation in the joint, why continue with the biologic? Can you speak with me about this at my next appointment?)

Nurse Domínguez-García called her the next morning. Valentina was medically trained, would spot oversimplification immediately, and deserved a mechanistically honest explanation — not a paternalistic “because the doctor says so.”

“Valentina, gracias por contactarme directamente — es la pregunta correcta y merece una explicación completa. La resonancia magnética normal en tu caso es exactamente lo que buscábamos cuando iniciamos el adalimumab. Quiero que entiendas lo que la resonancia está midiendo — y lo que no está midiendo — porque eso es lo que hace que la respuesta a tu pregunta no sea obvia.”

(Valentina, thank you for contacting me directly — it is the right question and it deserves a complete explanation. The normal MRI in your case is exactly what we were seeking when we started adalimumab. I want you to understand what the MRI is measuring — and what it is not measuring — because that is what makes the answer to your question not obvious.)

Valentina: “El reporte dice que no hay edema de médula ósea. El edema representá la inflamación aguda — eso lo entiendo. Si no hay edema, no hay inflamación activa. ¿Por qué necesito un biológico si no hay inflamación activa?”

“Correcto hasta ahí — el edema de médula ósea en la resonancia STIR representa la inflamación aguda en la articulación sacroilíaca: neutrófilos, macrófagos, las sustancias inflamatorias producidas por el TNF-alfa activando a esas células en el tejido óseo adyacente a la articulación. El adalimumab bloquea el TNF-alfa antes de que se una a sus receptores. Sin TNF-alfa, esa inflamación aguda no se sostiene. El edema desaparece. Eso es exactamente lo que el adalimumab está haciendo, y la resonancia normal lo confirma. La pregunta es: ¿qué pasa con esa inflamación si se para el adalimumab?”

(Correct up to that point — bone marrow edema on STIR MRI represents the acute inflammation in the sacroiliac joint: neutrophils, macrophages, the inflammatory substances produced by TNF-alpha activating those cells in the bone tissue adjacent to the joint. Adalimumab blocks TNF-alpha before it can bind its receptors. Without TNF-alpha, that acute inflammation is not sustained. The edema disappears. That is exactly what adalimumab is doing, and the normal MRI confirms it. The question is: what happens with that inflammation if adalimumab is stopped?)

Valentina: “El TNF-alfa vuelve a sus niveles basales.”

“Exacto. La vida media del adalimumab es de aproximadamente catorce días. Después de cuatro a seis semanas sin el medicamento, el adalimumab está prácticamente eliminado. La inflamación aguda regresa — el mismo edema que se veía al principio puede reaparecer en meses. Los estudios de seguimiento en pacientes con espondilitis axial que pararon los biológicos después de alcanzar remisión muestran que aproximadamente el cuarenta por ciento recayó en los primeros tres meses, y más del sesenta por ciento en el primer año. Pero lo que me preocupa más en tu caso no es solo la inflamación aguda — es lo que le pasa al daño estructural.”

(Exactly. The half-life of adalimumab is approximately fourteen days. After four to six weeks without the medication, adalimumab is practically eliminated. The acute inflammation returns — the same edema visible at the start may reappear within months. Follow-up studies in axial spondylitis patients who stopped biologics after achieving remission show approximately forty percent relapsed in the first three months, and more than sixty percent in the first year. But what concerns me most in your case is not only the acute inflammation — it is what happens to the structural damage.)

Valentina: “¿Qué quieres decir con daño estructural en este contexto?”

“Tu radiografía inicial ya mostró grado cuatro de sacroiliitis bilateral — fusión parcial — y dos esclerosis en los bordes de las vértebras L4/L5. El daño estructural es la formación de hueso nuevo en los bordes de las vértebras — los sindesmófitos — que se forman a través de un proceso llamado osificación endocondral en las zonas fibrocartilaginosas donde los ligamentos y el anulus fibrosus se insertan en el hueso vertebral. Ese proceso es impulsado por proteínas morfogenéticas óseas — BMP-2 y BMP-4 — y por la vía Wnt, que activan osteoblastos en los sitios que han tenido inflamación previa. Aquí está la parte crítica para entender: ese proceso — la vía BMP-Wnt de formación de hueso nuevo — es parcialmente independiente de la señal inflamatoria aguda del TNF-alfa que la resonancia magnética detecta.”

(Your initial x-ray already showed grade four bilateral sacroiliitis — partial fusion — and two corner scleroses at L4/L5 vertebrae. Structural damage is the new bone formation at vertebral corners — the syndesmophytes — that form through a process called endochondral ossification at the fibrocartilaginous zones where ligaments and the annulus fibrosus insert onto the vertebral bone. That process is driven by bone morphogenetic proteins — BMP-2 and BMP-4 — and by the Wnt pathway, which activate osteoblasts at sites that have had prior inflammation. Here is the critical part to understand: that process — the BMP-Wnt new bone formation pathway — is partially independent of the acute TNF-alpha inflammatory signal that MRI detects.)

Valentina paused. “Descoupled.”

“Sí — ese es el término en inglés que usamos. Los episodios inflamatorios previos en los sitios de inserción vertebral han establecido un microambiente con niveles elevados de BMPs y con la vía Wnt en un estado de activación parcial que puede continuar a una tasa baja incluso cuando la inflamación aguda está suprimida. Los estudios radiográficos en espondilitis axial durante el tratamiento biológico muestran que la progresión estructural continúa — más lenta que sin tratamiento, pero no cero — incluso en pacientes en remisión clínica completa e imagen magnética normal. Y hay un fenómeno adicional que complica esto: el TNF-alfa en la espondilitis activa sin tratar también induce la producción de DKK1 — un inhibidor endógeno de la vía Wnt. Cuando el adalimumab suprime el TNF-alfa, suprime también esa inducción de DKK1 — lo que significa que la vía Wnt puede quedar parcialmente desinhibida incluso durante el tratamiento biológico. Si se para el adalimumab, el TNF-alfa regresa, la inflamación aguda se acelera, y el proceso BMP-Wnt que estaba a tasa baja recibe ahora la aceleración inflamatoria completa.”

(Yes — that is the English term we use. Prior inflammatory episodes at the vertebral insertion sites have established a microenvironment with elevated BMP levels and the Wnt pathway in a state of partial activation that can continue at a low rate even when acute inflammation is suppressed. Radiographic studies in axial spondylitis during biologic treatment show that structural progression continues — slower than without treatment, but not zero — even in patients in complete clinical remission with normal MRI. And there is an additional phenomenon that complicates this: TNF-alpha in active untreated spondylitis also induces DKK1 production — an endogenous inhibitor of the Wnt pathway. When adalimumab suppresses TNF-alpha, it also suppresses that DKK1 induction — which means the Wnt pathway can be partially disinhibited even during biologic treatment. If adalimumab is stopped, TNF-alpha returns, acute inflammation accelerates, and the BMP-Wnt process that was at low rate now receives full inflammatory acceleration.)

Valentina was a nurse, but she had not studied immunology to this level. She processed the information quietly, then: “¿Y la radiografía simple sería lo que detectaría esa progresión estructural si ocurriera?”

“Exacto. La resonancia magnética es excepcional para el edema — la inflamación aguda. Para el hueso ya formado, la radiografía lateral de la columna lumbar y cervical es lo que detecta los sindesmófitos nuevos. Eso es por lo que se hace la radiografía anual aunque el paciente esté bien clínicamente. No es para confirmar que hay síntomas — es para detectar la formación de hueso nuevo silenciosa antes de que se establezca definitivamente. Lo que proponemos es hacer una radiografía lateral de la columna ahora para tener una comparación de base actual, y continuar el adalimumab mientras revisamos los datos anuales.”

(Exactly. MRI is exceptional for edema — acute inflammation. For already-formed bone, the lateral lumbar and cervical spine x-ray is what detects new syndesmophytes. That is why the annual x-ray is done even when the patient is clinically well. It is not to confirm there are symptoms — it is to detect silent new bone formation before it is definitively established. What we propose is to obtain a lateral spine x-ray now to have a current comparison baseline, and continue adalimumab while we review the annual data.)

Valentina agreed to continue adalimumab and to schedule a lateral spine x-ray that week. The x-ray was compared to her baseline from three years earlier. The radiologist's report: “Two small new vertebral corner erosions identified at L3 and L4 left-sided vertebral corners, not present on prior comparison films. No bridging syndesmophytes yet identified. Minimal increase in corner sclerosis compared to prior.” The structural progression had begun — silent, asymptomatic, visible only on the annual x-ray that Valentina had been correctly getting each year. Her rheumatologist discussed this finding with her at the next visit. The adalimumab had been slowing the process. It had not stopped it entirely, but the rate was substantially lower than untreated progression. The lesson for Valentina was clear: the normal MRI was evidence the drug was working, not evidence the drug could stop. She continued adalimumab. At her twelve-month surveillance x-ray: no new vertebral corner changes beyond the two already identified. The corner changes from the three preceding years of adalimumab remained stable.

Scenario 3: Roberto Cisneros-Torres — 51 years old, El Paso, Texas

Roberto Cisneros-Torres was a fifty-one-year-old retired high school principal in El Paso who had lived with ankylosing spondylitis for twenty-two years, since age twenty-nine. He had been diagnosed in the early days of biological therapy and had been through the natural history of a disease managed first with NSAIDs alone — seven years of naproxen that had controlled his pain incompletely — then sulfasalazine for peripheral enthesitis, then etanercept for eight years, and most recently certolizumab pegol, the PEGylated anti-TNF Fab fragment, begun six months earlier when etanercept seemed to be losing effectiveness at controlling his peripheral hip involvement.

After twenty-two years, his structural disease was substantial. Pelvic x-ray showed bilateral sacroiliac joint fusion — grade four, complete. Lateral lumbar spine x-ray showed partial syndesmophytes at L1 through L5 — right-sided at L1/L2, left-sided at L2/L3 (nearly bridging), right-sided at L3/L4, and bilateral at L4/L5 — with one complete syndesmophyte bridge at L2/L3 left lateral. Chest x-ray showed costovertebral joint fusion bilaterally at T4-T7, confirmed by CT. His BASMI at the time of certolizumab initiation was five point four: lumbar lateral flexion seven centimeters (normal reference ten or more), chest expansion two point four centimeters (normal five or more), modified Schober three point three centimeters (normal five or more), tragus-to-wall sixteen centimeters (normal less than ten indicating cervical spine involvement), intermalleolar distance eighty centimeters.

He also had bilateral hip involvement — asymmetric hip flexion contractures of ten degrees bilaterally on the Thomas test, and hip extension loss reducing his stride length. He had been referred to the rheumatology physical therapy program at the time of certolizumab initiation. He attended twice weekly, learning a home exercise program of posterior pelvic tilts, prone spinal extension, cervical retraction exercises, thoracic expansion with arm elevation, and hip flexor stretching. He performed these religiously for the first four months.

Certolizumab pegol produced a substantial pain response. His inflammatory back pain fell from nine of ten to three of ten. His morning stiffness shortened from one hundred twenty minutes to twenty-five minutes. His hip pain at rest resolved completely. He felt, in his words, “like a different person.” He stopped attending physical therapy at month four, reasoning that the exercises had been part of managing pain and since the biologic had handled the pain, they were no longer needed.

He missed four consecutive scheduled PT sessions, then canceled his next two with illness and vacation excuses. His PT coordinator noted the absence and flagged the rheumatology nursing team. His AS clinic nurse, María Gutiérrez-Herrera, had followed Roberto for three years. She knew his case, knew his BASMI trajectory, and understood the specific risk of exercise cessation in a patient with Roberto’s structural disease burden. She called him directly.

“Don Roberto, me alegra muchísimo que el certolizumab esté ayudando tanto. Un dolor de 9 a 3 es una diferencia enorme en la calidad de vida — eso es exactamente lo que esperábamos. Pero noto que no ha venido a fisioterapia en las últimas semanas, y quiero hablar con usted sobre eso específicamente, porque en su caso el ejercicio hace algo diferente al certolizumab — algo que el medicamento no puede hacer.”

(Don Roberto, I am very glad that certolizumab is helping so much. A pain from 9 to 3 is a huge difference in quality of life — that is exactly what we expected. But I notice you have not come to physical therapy in recent weeks, and I want to speak with you about that specifically, because in your case exercise does something different from certolizumab — something the medication cannot do.)

Roberto: “Me imaginé que iba a llamar. Mire, los ejercicios estaban bien cuando me dolía tanto, pero ahora que el medicamento tiene el dolor controlado, no veo el punto de seguir. Me duele hacer los ejercicios después de un día largo — ya no es necesario si no tengo el dolor de antes.”

“Entiendo completamente esa lógica — y tiene sentido si los ejercicios fueran para el dolor. Pero no son para el dolor, Don Roberto. Quiero explicarle lo que hacen en su columna específicamente, porque en su caso es más importante, no menos importante, que antes de empezar el certolizumab.”

(I completely understand that logic — and it makes sense if the exercises were for pain. But they are not for pain, Don Roberto. I want to explain what they do in your spine specifically, because in your case it is more important, not less important, than before starting certolizumab.)

Roberto: “¿Cómo pueden ser más importantes ahora?”

“Sus articulaciones sacroilíacas ya están fusionadas. Los puentes de hueso en la columna lumbar ya existen. Esas partes de la columna ya no se van a recuperar la movilidad con ningún medicamento ni ningún ejercicio — el daño estructural ya establecido es permanente. Lo que tenemos que proteger son los segmentos de la columna que todavía tienen movilidad — la parte de la columna cervical, la parte del toraco-lumbar donde el hueso nuevo todavía no ha formado puentes completos. En esos segmentos, el proceso de formación de hueso nuevo — que estaba siendo alimentado por la inflamación — no se puede detener completamente con el certolizumab. El certolizumab reduce la inflamación y eso ayuda. Pero hay una segunda forma de frenar la formación de hueso nuevo en esos sitios que no depende de la inflamación: el movimiento mecánico.”

(Your sacroiliac joints are already fused. The bone bridges in the lumbar spine already exist. Those parts of the spine will not recover mobility with any medication or any exercise — the already-established structural damage is permanent. What we must protect are the spinal segments that still have mobility — the part of the cervical spine, the part of the thoracolumbar spine where new bone has not yet formed complete bridges. In those segments, the new bone formation process — which was being fed by inflammation — cannot be stopped completely with certolizumab. Certolizumab reduces inflammation and that helps. But there is a second way to suppress new bone formation at those sites that does not depend on inflammation: mechanical movement.)

Roberto: “¿El movimiento mecánico frena la formación de hueso?”

“Sí. Las células del tejido ligamentoso y tendinoso de la columna — que son las células que están en riesgo de convertirse en células de hueso en la espondilitis — tienen sensores mecánicos. Cuando usted hace los ejercicios de extensión, esas células sienten la tensión mecánica y activan una cascada química interna que produce óxido nítrico y otras moléculas que frenan directamente la vía Wnt — que es la vía principal por la que se forman los sindesmófitos. Es una señal interna del tejido que dice: ‘este tejido está en uso, manten tu identidad de tejido blando, no te conviertas en hueso.’ Cuando no hay movimiento mecánico diario, esa señal desaparece. Y los estudios en pacientes con espondilitis en tratamiento biológico estable que pararon los ejercicios muestran que el BASMI — el índice que mide su movilidad total de la columna — empeora de manera medible en doce a dieciocho meses incluso mientras el biológico sigue activo.”

(Yes. The cells of the ligamentous and tendinous tissue of the spine — which are the cells at risk of becoming bone cells in spondylitis — have mechanical sensors. When you do the extension exercises, those cells feel the mechanical tension and activate an internal chemical cascade that produces nitric oxide and other molecules that directly suppress the Wnt pathway — which is the main pathway by which syndesmophytes form. It is an internal signal from the tissue that says: 'this tissue is in use, maintain your soft tissue identity, do not become bone.' When there is no daily mechanical movement, that signal disappears. And studies in spondylitis patients on stable biologic treatment who stopped exercises show that BASMI — the index that measures your total spinal mobility — worsens measurably within twelve to eighteen months even while the biologic remains active.)

Roberto: “¿O sea que el certolizumab no puede hacer lo que el ejercicio hace?”

“No puede. El certolizumab bloquea el TNF-alfa — la señal inflamatoria. El ejercicio activa los sensores mecánicos de las células del tejido. Son dos mecanismos completamente diferentes, dirigidos a la misma vía de formación de hueso, desde ángulos distintos. Necesita los dos. Pensé en un paralelismo: imaginése que tiene dos llaves de agua que alimentan una tubería que no puede dejar completamente cerrada. Una llave es el certolizumab — la tiene parcialmente cerrada. La otra llave es el ejercicio diario — también parcialmente cerrada. Si cierra solo una, el flujo no se detiene. Para controlar la formación de hueso en la columna de manera óptima, necesita las dos llaves parcialmente cerradas al mismo tiempo.”

(It cannot. Certolizumab blocks TNF-alpha — the inflammatory signal. Exercise activates the mechanical sensors of the tissue cells. They are two completely different mechanisms, directed at the same bone formation pathway, from different angles. You need both. I thought of a parallel: imagine you have two water taps feeding a pipe that you cannot close completely. One tap is certolizumab — you have it partially closed. The other tap is daily exercise — also partially closed. If you close only one, the flow does not stop. To control bone formation in the spine optimally, you need both taps partially closed at the same time.)

Roberto was quiet for a long moment. Then: “¿Cuánto tiempo lleva ya sin los ejercicios? Desde que empecé a cancelar.”

“Siete semanas. Es suficiente para que empecemos a perder el beneficio mecánico. No es suficiente para que haya cambios medibles en la radiografía todavía, pero sí es suficiente para que los tejidos de los segmentos móviles estén recibiendo menos estímulo protector. Lo importante ahora es retomar el programa de ejercicios — no desde cero, sino desde donde estaba cuando lo dejó.”

(Seven weeks. It is enough that we start losing the mechanical benefit. Not enough for measurable changes on x-ray yet, but enough that the tissues in the mobile segments are receiving less protective stimulus. The important thing now is to resume the exercise program — not from the beginning, but from where you left off when you stopped.)

Roberto returned to physical therapy the following week. Nurse Gutiérrez-Herrera documented the call and the clinical rationale in detail, noting that the patient’s understanding of the two-mechanism model — biologic for inflammation, exercise for mechanical Wnt suppression — was the cognitive frame most likely to sustain long-term adherence. She scheduled a BASMI re-measurement at six months.

At six months post-resumption: BASMI had remained at five point four — unchanged from certolizumab initiation six months earlier. At eighteen months post-resumption: BASMI five point five — clinically stable. Bilateral hip flexion contractures remained at ten degrees bilaterally. Lateral spine x-ray at eighteen months: no new syndesmophytes beyond those already present at certolizumab initiation. Roberto continued both certolizumab and his daily extension exercise program.

Nurse Gutiérrez-Herrera had seen what happened to a similar patient who had stopped exercises for two years without intervention: that patient’s BASMI had progressed from five point two to six point one on stable TNF inhibitor therapy, bilateral hip contractures had progressed from eight to nineteen degrees, and the lateral x-ray had shown two new complete syndesmophyte bridges in the lower thoracic spine. The irreversible progress of those twenty-two months would not return regardless of any future change in treatment or exercise. The seven-week intervention call had been worth the time.

What axial spondyloarthritis and ankylosing spondylitis clinic nurses working with Spanish-speaking patients need to know about these three conversations

The three scenarios above each address a different layer of the AS treatment architecture that patients commonly misunderstand. Eduardo’s error was about NSAIDs: he correctly understood them as pain medications and correctly observed that his pain was controlled, but missed that NSAIDs in AS suppress a PGE2-driven entheseal osteogenic signal that is independent of their analgesic effect. Stopping the NSAID when pain improves removes both the analgesic protection and the structural protection simultaneously — only the analgesic loss is immediately perceptible. Valentina’s error was about biologics and MRI: she correctly interpreted the MRI report as showing no active inflammation, correctly concluded the biologic was producing the expected response, but missed that MRI resolution is evidence the drug is working rather than evidence the disease has resolved — and that structural damage via BMP-Wnt osteogenesis continues even during MRI-documented biologic remission, and accelerates when the biologic is withdrawn. Roberto’s error was about exercise: he correctly identified that his pain was controlled by certolizumab, correctly concluded that pain-management exercises were no longer needed, but missed that his physical therapy exercises were not primarily for pain — they were the only available source of mechanical Wnt suppression in the remaining mobile spinal segments, a protection that certolizumab cannot provide and that becomes more rather than less important as the disease advances and the remaining mobile segments narrow.

These three errors share the structure that makes AS patient education particularly challenging: the patient is making a reasonable inference from an accurate observation. The inference is wrong not because the observation is wrong but because the observation is incomplete — it captures one mechanism (pain relief, MRI resolution, pain control) while missing the parallel mechanism (entheseal osteogenesis, structural progression, mechanical Wnt suppression). The AS clinic nurse’s role is not to dispute the patient’s observation but to complete it: to add the second mechanism that was not visible from the patient’s perspective and that changes the conclusion.

The AS structural model the nurse must communicate in Spanish can be summarized as a chronic inflammatory enthesopathy in which the acute inflammation and the new bone formation are driven by related but partially independent molecular pathways. Acute inflammation is visible (MRI, CRP, symptoms), suppressible (NSAIDs, biologics), and reversible in direction. Structural bone formation is invisible (asymptomatic, not reflected in CRP, not seen on early MRI), partially suppressible (by continuous NSAIDs, by biologics slowing but not stopping the process, by daily mechanical loading), and irreversible once established. The annual lateral spine x-ray is the surveillance tool that operates in the invisible domain — the domain of silent new bone formation — and it is the only tool that catches structural progression before it is permanent.

The five statements every axial spondyloarthritis clinic nurse should be able to make clearly in Spanish:

First: NSAIDs do two things in AS, not one. “El antiinflamatorio no esteroidio hace dos cosas en su enfermedad: le quita el dolor, y bloquea una señal química que activa la formación de hueso nuevo en la columna. Cuando para el medicamento porque no le duele, pierde los dos efectos. El efecto sobre el hueso es el que más importa a largo plazo, y ese no se siente cuando se pierde.” (The non-steroidal anti-inflammatory does two things in your disease: it relieves your pain, and it blocks a chemical signal that activates new bone formation in the spine. When you stop the medication because you do not hurt, you lose both effects. The effect on bone is the one that matters most long-term, and that is not felt when it is lost.)

Second: MRI remission is the biologic working, not the disease resolved. “La resonancia magnética normal es exactamente lo que buscamos cuando iniciamos el biológico. Es la confirmación de que el medicamento está funcionando. No es la confirmación de que la enfermedad ha desaparecido. Si para el medicamento, la inflamación que producía ese edema regresa en semanas. Y con ella regresa la señal para que el hueso siga formándose en la columna.” (The normal MRI is exactly what we seek when we start the biologic. It is confirmation that the medication is working. It is not confirmation that the disease has disappeared. If you stop the medication, the inflammation that was producing that edema returns within weeks. And with it returns the signal for bone to continue forming in the spine.)

Third: structural damage is silent and irreversible — the x-ray is the only warning. “La formación de hueso nuevo en la columna — los puentes óseos entre las vértebras — no duele mientras ocurre. No cambia el análisis de sangre. No aparece en la resonancia en sus etapas tempranas. Solo aparece en la radiografía anual. Y una vez que el puente de hueso se ha formado, no desaparece con ningún tratamiento. La radiografía anual es la única forma de detectarlo antes de que sea permanente.” (New bone formation in the spine — the bony bridges between vertebrae — does not hurt while it is occurring. It does not change the blood test. It does not appear on MRI in its early stages. It only appears on the annual x-ray. And once the bone bridge has formed, it does not disappear with any treatment. The annual x-ray is the only way to detect it before it is permanent.)

Fourth: exercise in AS is mechanical therapy, not pain therapy. “Los ejercicios de extensión de la columna en la espondilitis no son para el dolor — son para mantener la movilidad de los segmentos que todavía se mueven. El movimiento físico activa una señal interna en los tejidos de la columna que frena la misma vía de formación de hueso que la inflamación activa. El biológico no puede hacer eso — es un mecanismo diferente. Los dos son necesarios al mismo tiempo.” (Spinal extension exercises in spondylitis are not for pain — they are to maintain the mobility of the segments that still move. Physical movement activates an internal signal in the spinal tissues that suppresses the same bone formation pathway that inflammation activates. The biologic cannot do that — it is a different mechanism. Both are needed at the same time.)

Fifth: feeling well on treatment is evidence treatment is working, not evidence treatment can stop. “Sentirse bien, la resonancia normal, el dolor controlado — todas esas son señales de que el tratamiento está funcionando. No son señales de que la enfermedad despareció. La espondilitis anquilosante no desparece — se controla. El control requiere tratamiento continuo. Cuando el tratamiento se para, el control se pierde.” (Feeling well, a normal MRI, controlled pain — all of those are signs that treatment is working. They are not signs that the disease has gone away. Ankylosing spondylitis does not go away — it is controlled. Control requires continuous treatment. When treatment is stopped, control is lost.)

Axial spondyloarthritis is one of the few rheumatic diseases in which the treatment target — reducing inflammation — and the disease consequence that causes disability — structural bone formation — are driven by related but partially independent mechanisms. The AS clinic nurse who understands this decoupling can explain it in Spanish, and who can convey to the patient that feeling well means the treatment is working rather than the disease is gone, is operating at the exact interface where patient decisions are made and where irreversible structural damage is prevented.

“El dolor que ya no siente es la señal de que el tratamiento está haciendo su trabajo. Es la razón para continuar — no para parar.”

(The pain you no longer feel is the sign that treatment is doing its job. It is the reason to continue — not to stop.)

That sentence, said with mechanical understanding and in the language the patient speaks, is worth more than any compliance reminder.

Internal links: Spanish for rheumatology clinic nurses · Spanish for psoriatic arthritis clinic nurses · Spanish for Sjögren’s syndrome clinic nurses · Spanish for systemic lupus erythematosus clinic nurses