Ankylosing Spondylitis

Ankylosing Spondylitis: A Clinical Physical Therapy Guide

1. Overview

Ankylosing Spondylitis (AS) is a chronic, progressive inflammatory rheumatic disease primarily affecting the axial skeleton, including the sacroiliac (SI) joints, spine, and peripheral joints, as well as entheses (sites where tendons or ligaments attach to bone). It is classified under the broader term of Spondyloarthritis. The disease is characterized by chronic inflammation that can lead to pain, stiffness, and ultimately structural damage, including new bone formation (syndesmophytes) which can result in spinal fusion (ankylosis) and loss of spinal mobility, commonly referred to as "bamboo spine."

The prevalence of AS varies globally, affecting approximately 0.1-0.3% of the adult population, with a higher incidence in men and typical onset in late adolescence or early adulthood (before 45 years of age). Genetic predisposition plays a significant role, with over 90% of AS patients testing positive for the HLA-B27 allele. However, HLA-B27 positivity alone does not guarantee disease development, indicating a complex interplay of genetic, environmental, and immune factors.

Clinical presentation typically involves inflammatory back pain, characterized by insidious onset, morning stiffness lasting longer than 30 minutes, improvement with exercise but not rest, and nocturnal pain in the second half of the night. Fatigue is a common and often debilitating symptom. Extra-articular manifestations can include acute anterior uveitis (eye inflammation), inflammatory bowel disease (IBD), psoriasis, and cardiovascular involvement. Early diagnosis is crucial to mitigate disease progression and improve long-term outcomes, often involving a combination of clinical assessment, imaging (X-ray, MRI), and laboratory markers.

Physical therapy (PT) is a cornerstone of AS management, playing an indispensable role in controlling symptoms, preserving spinal and peripheral joint mobility, preventing deformity, enhancing functional capacity, and improving the overall quality of life for individuals living with AS. A comprehensive PT approach is vital throughout all stages of the disease, adapting to fluctuating disease activity and individual patient needs.

2. Functional Anatomy

Understanding the functional anatomy affected by Ankylosing Spondylitis is critical for effective physical therapy intervention. The disease primarily targets the axial skeleton and entheses, leading to specific biomechanical dysfunctions.

• Sacroiliac (SI) Joints: The SI joints are typically the first site of inflammation (sacroiliitis). Unilateral or bilateral involvement can lead to significant pain in the buttock and lower back regions, often radiating down the posterior thigh. Chronic inflammation can cause joint erosion, sclerosis, and eventually fusion, severely limiting the joints' normal subtle movements, which are crucial for shock absorption and load transfer between the spine and lower limbs. This can alter gait mechanics and contribute to compensatory stresses on other spinal segments.
• Spine: AS affects the entire spine, leading to spondylitis. Inflammation initially causes pain and stiffness. Over time, ossification of the anulus fibrosus and ligaments, particularly the anterior longitudinal ligament, forms syndesmophytes, which can bridge vertebral bodies, leading to progressive spinal fusion.
  • Lumbar Spine: Typically loses its normal lordosis, leading to a flattened back and increased stress on adjacent segments.
  • Thoracic Spine: Often develops an exaggerated kyphosis (hyperkyphosis), which can be severe, causing a stooped posture. This restricts chest wall expansion.
  • Cervical Spine: Can also fuse, leading to a rigid neck with limited range of motion, often in a flexed posture, profoundly impacting daily activities like driving or looking upwards.
• Entheses: Inflammation at entheses (enthesitis) is a hallmark feature. Common sites include the Achilles tendon insertion, plantar fascia, costochondral junctions, greater trochanter, and ischial tuberosities. Enthesitis causes localized pain, tenderness, and swelling, contributing to reduced function and mobility. Chronic enthesitis can lead to bone spur formation and calcification.
• Peripheral Joints: While primarily axial, peripheral joint involvement occurs in about 30-40% of patients, most commonly affecting the hips and shoulders. Hip involvement can be particularly disabling, leading to pain, stiffness, and severe limitation of gait and functional activities. Knee and ankle involvement is less common but can occur.
• Thoracic Cage: Inflammation of the costovertebral, costosternal, and manubriosternal joints restricts chest wall expansion, leading to decreased vital capacity and a restrictive pattern of lung disease. This can be exacerbated by thoracic hyperkyphosis.
• Musculature: Chronic pain, inflammation, and postural changes lead to muscle imbalances. Flexor muscles (e.g., hip flexors, pectorals) can become tight, while extensor muscles (e.g., back extensors, gluteals, deep neck flexors) often weaken due to disuse and altered biomechanics. This perpetuates poor posture and further compromises mobility.

3. Four Phases of Rehabilitation

Physical therapy for Ankylosing Spondylitis is tailored to the patient's current disease activity, level of pain, functional limitations, and stage of disease progression. A phased approach allows for systematic and progressive intervention.

Phase 1: Acute/Inflammatory Phase (Pain Management & Early Mobility)

This phase focuses on managing acute pain and inflammation, preventing further deconditioning, and educating the patient.

• Goals: Reduce pain and muscle spasm, minimize inflammation, maintain current range of motion (ROM), educate on disease and self-management.
• Interventions:
  • Modalities: Cryotherapy (ice) for acute inflammation, thermotherapy (heat) for muscle relaxation and stiffness relief. TENS for pain modulation.
  • Gentle ROM Exercises: Active-assisted or gentle active ROM for axial and peripheral joints, avoiding end-range stress. Focus on small, controlled movements.
  • Posture Education: Instruction on neutral spine awareness, ergonomic sleeping positions (e.g., firm mattress, avoid excessive pillows), and avoiding prolonged static postures.
  • Breathing Exercises: Diaphragmatic breathing to improve respiratory function and reduce chest wall stiffness.
  • Activity Modification: Encourage gentle, low-impact activities within pain limits. Advise against high-impact sports or heavy lifting during flare-ups.
  • Patient Education: Explaining the disease process, importance of medication adherence, energy conservation techniques, and pain coping strategies.

Phase 2: Subacute/Remission Phase (Restoration of Function & Mobility)

Once acute symptoms subside, the focus shifts to restoring mobility, improving strength, and enhancing functional capacity.

• Goals: Increase spinal and peripheral joint mobility, improve muscle strength and endurance, enhance postural control, improve functional activities and quality of life.
• Interventions:
  • Progressive ROM Exercises: Emphasize spinal mobility, particularly extension (e.g., prone prop, cat-cow stretches modified for AS), rotation, and lateral flexion. Incorporate specific exercises for hip and shoulder mobility. Aquatic therapy is highly beneficial due to buoyancy and resistance.
  • Strengthening Exercises: Focus on core stability (transversus abdominis, multifidus), spinal extensors, gluteal muscles, and scapular stabilizers. Use low-load, high-repetition exercises.
  • Stretching: Address muscle tightness in hip flexors, hamstrings, pectorals, and latissimus dorsi. Sustained holds with proper technique.
  • Postural Re-education: Specific exercises and mirror feedback to promote an upright posture. Ergonomic advice for work and home environments.
  • Advanced Breathing Exercises: Segmental breathing, deep inspirations to maximize chest expansion.
  • Aerobic Conditioning: Low-impact activities like walking, cycling, swimming, or elliptical training to improve cardiovascular fitness and reduce fatigue.
  • Balance and Proprioception: Exercises to improve balance, especially if spinal rigidity alters the center of gravity.

Phase 3: Chronic/Maintenance Phase (Long-Term Management & Prevention of Deformity)

This phase emphasizes sustaining improvements, preventing disease progression, and fostering long-term self-management.

• Goals: Maintain gains in mobility and strength, prevent progression of spinal fusion and deformity, optimize quality of life, promote self-efficacy.
• Interventions:
  • Home Exercise Program (HEP) Progression: Regular review and progression of the HEP, ensuring adherence and motivation. May include more advanced exercises.
  • Regular Structured Exercise: Encourage participation in regular exercise routines combining mobility, strengthening, and aerobic components. Group exercise classes (e.g., adapted Pilates, yoga, Tai Chi) can be beneficial.
  • Advanced Postural Control: Continue to reinforce proper body mechanics for daily activities, lifting, and carrying.
  • Flare-up Management Plan: Educate on recognizing early signs of a flare-up and implementing acute phase strategies.
  • Monitoring: Regular assessment of spinal mobility (e.g., Modified Schober test, chest expansion), pain levels, and functional status.
  • Psychosocial Support: Address psychological impacts of chronic disease, refer to support groups or counseling if needed.
  • Ergonomic Adaptation: Ensure continued ergonomic suitability of workstations, car seats, and home environments.

Phase 4: Advanced/Deformity Management Phase (Compensatory Strategies & Functional Adaptation)

For patients with significant structural changes and advanced ankylosis, the focus shifts to optimizing function despite deformity and preventing secondary complications.

• Goals: Maximize functional independence, manage pain effectively, prevent falls and secondary complications, improve overall quality of life despite limitations.
• Interventions:
  • Compensatory Strategies: Teach adaptive techniques for activities of daily living (ADLs) to overcome spinal rigidity (e.g., using vision to scan surroundings with a fixed neck, reaching strategies).
  • Strengthening for Compensation: Focus on strengthening muscles that support compensatory postures and improve stability (e.g., gluteals, quadriceps to aid getting up from a chair with a rigid spine).
  • Balance Training: Intensive balance and gait training to prevent falls, as altered spinal mechanics and kyphosis can shift the center of gravity.
  • Adaptive Equipment: Recommend assistive devices (e.g., reachers, raised toilet seats, specialized seating) to improve independence.
  • Respiratory Support: Maximize remaining chest expansion and vital capacity through targeted breathing exercises. Referrals for pulmonary function tests if needed.
  • Pain Management: Often involves a multidisciplinary approach, including pain psychology, medications, and appropriate physical modalities.
  • Patient and Family Education: Comprehensive education on living with chronic AS, safety measures, and available resources.

4. Research

The efficacy of physical therapy in the management of Ankylosing Spondylitis is well-supported by a robust body of research. Numerous studies and clinical guidelines consistently highlight the critical role of exercise and rehabilitation in improving outcomes for AS patients.

• Exercise Efficacy: Randomized controlled trials (RCTs) and meta-analyses have demonstrated that regular exercise significantly improves spinal mobility, reduces pain and stiffness, enhances functional capacity, and improves quality of life in individuals with AS. A Cochrane review concluded that supervised exercise programs, both land-based and aquatic, are beneficial for reducing disease activity and improving physical function.
• Specific Exercise Modalities: Research explores various exercise types. Aquatic therapy is often preferred due to the buoyancy that reduces joint loading and facilitates movement. Pilates, yoga, and specific spinal extension exercises are also shown to be effective in improving spinal mobility and postural alignment. Strengthening programs focusing on core stability and extensor muscles are vital for counteracting postural changes.
• Combined Therapy Approach: Studies show that physical therapy optimally complements pharmacological treatments, particularly the use of NSAIDs and biologic disease-modifying antirheumatic drugs (bDMARDs). Biologics reduce inflammation, which can allow patients to engage more effectively in physical therapy, thereby maximizing the benefits of both interventions.
• Patient Education and Self-Management: Research emphasizes the importance of patient education and self-management programs. Long-term adherence to a home exercise program is crucial for maintaining gains and preventing progression. Digital health interventions and telerehabilitation are emerging areas showing promise for delivering exercise programs and monitoring progress, especially for those with limited access to in-person therapy.
• Outcome Measures: Validated outcome measures such as the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), and Ankylosing Spondylitis Quality of Life (ASQoL) are widely used in research to assess the effectiveness of interventions and track disease progression, guiding evidence-based practice.
• Future Directions: Ongoing research aims to personalize exercise prescriptions based on individual disease activity and genetic profiles, investigate the long-term impact of exercise on disease progression, and explore the integration of wearable technology and virtual reality in rehabilitation programs for AS.