Ankylosing Spondylitis

Spine

Overview

Ankylosing spondylitis (AS) is a chronic inflammatory arthropathy primarily affecting the axial skeleton, characterized by progressive spinal fusion and reduced mobility. The condition typically presents in young to middle-aged males with inflammatory back pain and may progress to severe kyphosis and functional limitation. Early diagnosis and management are critical to slow progression and maintain quality of life.

Pathophysiology

AS is an HLA-B27-associated autoimmune condition involving chronic inflammation of the spine and sacroiliac joints. The inflammatory process leads to ossification of spinal ligaments and intervertebral disc fibrosis, progressively fusing vertebrae into a rigid column. This pathological process extends from the sacroiliac joints upward, with inflammation preceding structural changes. Peripheral joint involvement and extra-articular manifestations (uveitis, enthesitis) occur in 30-40% of cases. The rigid spine becomes vulnerable to fracture from minor trauma.

Typical Presentation

Site

Sacroiliac joints, lumbar and thoracic spine; may extend to cervical spine, hips, shoulders, and peripheral joints; entheseal pain at heels, tibial tuberosities, and ribs

Quality

Inflammatory back pain; morning stiffness; night pain often waking patient in second half of night; progressive loss of spinal extension and rotation; peripheral joint pain if involved

Intensity

Highly variable; ranges from mild morning stiffness to severe debilitating pain with progressive functional limitation; inflammatory markers (ESR, CRP) may correlate with symptoms

Aggravating

Prolonged rest and inactivity; morning stiffness (typically >30 minutes, improving with movement); static postures; cold weather; stress

Relieving

Physical activity and exercise; movement and mobilization; NSAIDs; heat application; forward bending in early disease; biologics (TNF inhibitors) in later disease

Associated

Morning stiffness lasting >1 hour; progressive kyphosis and loss of spinal extension; chest wall pain and reduced chest expansion; fatigue; depression and anxiety from chronic disease; uveitis (25% of cases); peripheral arthritis; enthesitis; inflammatory bowel disease connection (10%)

Orthopaedic Tests

Schober Test (Modified)

Procedure

Patient stands upright; mark the lumbosacral junction (S1) and a point 10 cm above. Instruct patient to bend forward maximally without bending knees. Measure the distance between marks.

Positive Finding

Increase in distance of <5 cm (normal is ≥5 cm), indicating reduced lumbar flexion and spinal mobility loss

Sensitivity / Specificity

70% / 89%

Viitanen et al., 1992, British Journal of Rheumatology

Interpretation

Suggests restricted lumbar spine flexion consistent with ankylosing spondylitis or other axial spondyloarthropathies; helps monitor disease progression

Occiput-to-Wall Distance Test

Procedure

Patient stands with heels and back against a wall, attempting to touch the occiput (back of head) to the wall while keeping gaze level. Measure the distance from occiput to wall.

Positive Finding

Distance >0 cm (inability to touch head to wall), indicating cervical and thoracic kyphosis

Sensitivity / Specificity

null / null

Interpretation

Detects hyperkyphosis of the cervical and thoracic spine; common in advanced ankylosing spondylitis and indicates postural change and disease severity

Chest Expansion (Thoracic Mobility)

Procedure

Measure chest circumference at the 4th intercostal space during maximal expiration and maximal inspiration. Calculate the difference.

Positive Finding

Chest expansion <2.5 cm (normal is ≥2.5 cm), indicating restricted thoracic mobility and costovertebral involvement

Sensitivity / Specificity

61% / 93%

Moll & Wright, 1971, Annals of the Rheumatic Diseases

Interpretation

Reflects thoracic spine and costochondral joint stiffness; important marker of disease activity and pulmonary function impact in ankylosing spondylitis

Tragus-to-Wall Distance Test

Procedure

Patient stands upright with heels and back against a wall. Measure the perpendicular distance from the tragus of the ear to the wall.

Positive Finding

Distance >0 cm (tragus does not touch wall), indicating forward head posture and cervical kyphosis

Sensitivity / Specificity

null / null

Interpretation

Quantifies cervical flexion deformity; used to monitor postural deterioration and assess severity of spinal changes in advanced disease

Finger-to-Floor Distance Test

Procedure

Patient stands with feet together and bends forward maximally without bending knees, allowing arms to hang. Measure the distance from fingertips to floor.

Positive Finding

Increased distance from floor (typically >0 cm), indicating reduced spinal and hip flexion mobility

Sensitivity / Specificity

null / null

Interpretation

Non-specific but practical measure of combined spinal and hip flexion; useful for tracking functional mobility and disease progression over time

Lateral Lumbar Flexion Test

Procedure

Patient stands upright and bends sideways (laterally) to each side maximally. Measure distance from fingertip to floor or assess lateral spinal deviation visually.

Positive Finding

Reduced lateral flexion range bilaterally, or asymmetrical restriction, suggesting spinal stiffness and decreased mobility

Sensitivity / Specificity

null / null

Interpretation

Assesses axial spine mobility in the frontal plane; helps detect symmetrical stiffening characteristic of ankylosing spondylitis

⚠ Red Flags

  • •Spinal fracture risk—minor trauma causing neurological deficits or severe pain in rigid spine
  • •Acute anterior uveitis—sudden eye pain, photophobia, redness requiring urgent ophthalmology review
  • •Cauda equina syndrome—rare but serious; progressive neurological deficit, saddle anesthesia, bowel/bladder dysfunction
  • •Cardiac involvement—conduction abnormalities, aortic regurgitation; refer if palpitations or syncope
  • •Severe progressive kyphosis causing cardiopulmonary compromise
  • •Suspected spinal infection or malignancy in atypical presentations
  • •Uncontrolled inflammatory markers despite therapy—consider rheumatology review

⚡ Yellow Flags

  • •Psychosocial distress and depression related to progressive disability and loss of function
  • •High health anxiety and catastrophizing regarding disease progression
  • •Avoidance behavior and kinesiophobia limiting therapeutic exercise adherence
  • •Social isolation due to reduced mobility and chronic pain
  • •Work-related stress and occupational disability concerns
  • •Poor medication adherence and compliance with biologic therapy
  • •Relationship strain and sexual dysfunction from pain and stiffness
  • •Sleep disturbance from nocturnal inflammatory pain affecting quality of life

Osteopathic Techniques

Region

Thoracic spine and rib cage

Technique

Articulation

Rationale

Gentle articulation of thoracic segments and rib joints maintains segmental mobility and chest wall expansion, counteracting progressive kyphosis and rib cage restriction. Improving thoracic extension and rotation helps compensate for lumbar fusion and reduces restrictive patterns.

Region

Sacroiliac joints and lumbar spine

Technique

Soft Tissue

Rationale

Sustained soft tissue release of paraspinal muscles, quadratus lumborum, and hip flexors reduces compensatory muscle tension and myofascial pain. This addresses secondary muscular restrictions without aggressive mobilization that may provoke inflammation in an already unstable spine.

Region

Hip joints and iliopsoas

Technique

MET

Rationale

Muscle energy techniques reduce hip flexor tightness and hip restriction, addressing functional limitations from progressive spinal fusion. Improved hip mobility compensates for reduced lumbar extension and helps maintain upright posture and normal gait mechanics.

Region

Cervical spine and upper thoracic

Technique

Functional

Rationale

Functional techniques gently support the cervical spine into positions of ease, maintaining available mobility without aggressive manipulation. This is particularly important in advanced AS where rigid fusion limits tolerance for HVLA techniques and fracture risk is high.

Region

Rib cage and costal structures

Technique

Lymphatic

Rationale

Lymphatic drainage techniques support thoracic lymphatic flow and reduce inflammation-related fluid accumulation. This complements conventional anti-inflammatory management and may reduce pain and improve chest wall mobility.

Region

Cranial and cervical fascia

Technique

Cranial

Rationale

Gentle cranial techniques addressing tension in the dura mater and cervical fascia help normalize spinal mobility patterns and reduce referred pain patterns. Reduced fascial restriction may improve overall spinal mechanics and reduce compensatory tension.

Add-On Approaches

Chinese Medicine

TCM conceptualizes AS as Bi syndrome (obstruction) with underlying Kidney Yang deficiency. Acupuncture points GV3 (Mingmen), GV4 (Mingmen variant), UB23 (Shenshu), UB52 (Zhishi), and points along the Du Mai meridian are traditionally used. Herbal formulas such as Du Huo Ji Sheng Tang (Angelica Pubescens and Eucommia Combination) may support circulation and reduce stiffness. Moxibustion may provide warming and circulatory benefits.

Chiropractic

Chiropractic management must be cautious due to fracture risk in advanced AS. Gentle mobilization and articulation may be used; HVLA manipulation is generally contraindicated in moderate-to-advanced disease due to rigidity and fracture vulnerability. Some chiropractors employ flexion-distraction techniques to decompress disc spaces and improve segmental mobility, though evidence is limited. Emphasis should remain on postural correction and exercise prescription.

Physiotherapy

Progressive exercise programs including aerobic activity (swimming, walking), spinal mobility exercises, and postural training are cornerstones of AS management. Physiotherapy emphasizes extension and rotation exercises, chest expansion exercises, and hip mobility work. Breathing exercises and chest wall stretching help maintain thoracic function. Balance and proprioceptive training reduce fall risk in rigid spines. Regular physical activity is associated with slower radiographic progression.

Remedial Massage

Remedial massage addresses secondary muscle tension, myofascial trigger points in paraspinal muscles, hip flexors, and thoracic musculature. Deep tissue techniques reduce muscle guarding and improve circulation to chronically tense areas. Regular massage may enhance compliance with exercise programs by reducing pain and improving tissue elasticity. Avoid aggressive pressure over inflamed sacroiliac joints and practice caution around rigid spinal segments.

Rehabilitation Exercises

Spinal Extension and Chest Wall Opening (Wall-Assisted)

PosturalBeginner

Cervical and Thoracic Rotation in Sitting

Range of MotionBeginner

Hip Flexor and Psoas Stretch (Lunge Position)

StretchingBeginner

Abdominal Core Activation (Transverse Abdominis Engagement)

StrengtheningBeginner

Thoracic Spine Mobilization with Foam Roller (Supported Extension)

Range of MotionIntermediate

Quadratus Lumborum Stretch (Supported Side Bend)

StretchingIntermediate

Gluteal and Hip Extensor Strengthening (Bridging with Holds)

StrengtheningIntermediate

Standing Balance and Proprioceptive Training (Tandem Stance)

BalanceIntermediate

Swimming or Water-Based Aerobic Activity

CardiovascularIntermediate

Combined Spinal Rotation and Lateral Flexion (Seated Twist-Reach)

Range of MotionIntermediate

Progressive Spinal Extensors and Back Support (Modified Prone Superman)

StrengtheningAdvanced

Dynamic Balance and Gait Training with Obstacles

BalanceAdvanced

Referral Criteria

  • •Suspected AS diagnosis or confirmation needed—rheumatology referral for HLA-B27 testing, inflammatory markers, and imaging (X-ray, MRI) to confirm diagnosis and assess disease severity
  • •Acute inflammatory flare unresponsive to NSAIDs—consider rheumatology referral for biologic therapy (TNF inhibitors) assessment
  • •Acute anterior uveitis or other eye symptoms—urgent ophthalmology referral
  • •Progressive kyphosis affecting respiratory function or quality of life—orthopedic or spinal surgeon consultation for possible corrective osteotomy
  • •Spinal fracture or neurological symptoms following trauma—emergency imaging and spinal surgery consultation; high risk of serious injury in rigid spine
  • •Severe functional limitation despite conservative management—consider occupational therapy and vocational rehabilitation
  • •Cardiac symptoms (palpitations, syncope) or conduction abnormalities—cardiology referral to assess for aortic regurgitation or conduction disease
  • •Inflammatory bowel disease symptoms—gastroenterology referral for evaluation and coordination of care
  • •Uncontrolled inflammatory markers or inadequate response to current therapy—rheumatology review for optimization of biologic or conventional DMARD therapy
  • •Depression, anxiety, or psychosocial distress affecting adherence—psychology or mental health referral for supportive therapy
  • •Atypical presentation or rapidly progressive disease—return to rheumatology for diagnostic clarification and management adjustment