Introduction / Definition

Ankle osteoarthritis is a debilitating degenerative disorder of the talocrural (tibiotalar) joint characterized by progressive articular cartilage loss, subchondral sclerosis, osteophyte formation, and painful loss of sagittal motion. Although non-weightbearing quality-of-life scores in advanced ankle osteoarthritis mirror those seen in end-stage hip or knee arthropathy, its mechanical and biological profile differs substantially. Ankle arthrodesis (tibiotalar fusion) eliminates articular motion across the joint and remains the historic reference standard for severe, symptomatic disease.

Epidemiology

Unlike hip and knee osteoarthritis, which are overwhelmingly primary degenerative processes, primary ankle osteoarthritis represents fewer than 10% of presentations. The overwhelming majority (approximately 70–80%) are post-traumatic, originating from previous intra-articular fractures (malleolar or tibial pilon fractures) or recurrent ankle instability and severe ligamentous injuries. The remainder stem from inflammatory arthropathies (rheumatoid arthritis, seronegative spondyloarthropathies), septic arthritis sequelae, haemochromatosis, avascular necrosis of the talus, or Charcot neuroarthropathy.

Relevant Anatomy

• Articular Geometry: The talocrural joint is a constrained, highly congruent ginglymus (hinge) joint bounded by the tibial plafond, medial malleolus, and lateral malleolus (fibula). The talar dome is wider anteriorly than posteriorly, inducing slight external rotation of the talus during full dorsiflexion.
• Cartilage Characteristics: Ankle articular cartilage is thin (1–2 mm on average) compared with that of the femoral head or condyles, but exhibits higher compressive stiffness and proteoglycan density. However, once mechanical congruity is lost (such as a 1 mm lateral displacement of the fibula, which alters talar contact areas by over 40%), contact stresses escalate rapidly, precipitating wear.
• Kinematics: Normal total sagittal range of motion is approximately 15°–20° of dorsiflexion to 40°–50° of plantarflexion. Normal level-ground bipedal gait requires roughly 10° of dorsiflexion and 15° of plantarflexion. Adjacent compensatory motion occurs predominantly through the subtalar joint and transverse tarsal (Chopart) joints.
• Neurovascular Relations: Anteriorly, the anterior neurovascular bundle (deep peroneal nerve and anterior tibial vessels) courses beneath the extensor retinaculum between the extensor hallucis longus (EHL) and tibialis anterior (TA) tendons. Posteriorly, the posterior tibial neurovascular bundle lies within the tarsal tunnel behind the medial malleolus, vulnerable to traction and screw overpenetration.

Classification

Several classifications exist to stage radiological severity, determine bone loss, and assist surgical planning:

Takakura Classification (Modified by Tanaka)

• Stage I: Osteophyte formation and subchondral sclerosis without joint space narrowing.
• Stage II: Joint space narrowing localized to the medial aspect without subchondral bone contact.
• Stage IIIA: Obliteration of the joint space with subchondral bone contact isolated to the medial malleolus.
• Stage IIIB: Obliteration of the joint space extending across the horizontal superior surface of the talar dome.
• Stage IV: Obliteration of the entire joint space with complete tibiotalar bone-to-bone contact.

Canadian Orthopaedic Foot & Ankle Society (COFAS) Classification

• Type 1: Isolated tibiotalar joint arthritis.
• Type 2: Tibiotalar arthritis with intra-articular varus or valgus deformity.
• Type 3: Tibiotalar arthritis with extra-articular deformity (e.g., supramalleolar tibial malunion or hindfoot inframalleolar deformity).
• Type 4: Tibiotalar arthritis with significant adjacent hindfoot arthritis (subtalar or midtarsal).

Clinical Presentation & Examination

Symptoms

Patients typically report dull, aching joint pain exacerbated by prolonged weightbearing, uneven terrain, and impact activities. Mechanical symptoms include stiffness, morning gel phenomenon, startup pain, and catching or crepitus from impinging osteophytes.

Physical Examination

• Inspection: Evaluate standing alignment from the front, side, and rear. Note coronal hindfoot alignment (varus vs valgus), compensatory forefoot pronation/supination, surgical scars, and skin integrity.
• Palpation: Pinpoint maximum tenderness over the anterior tibiotalar joint line, medial or lateral gutters, and examine adjacent joints (subtalar, talonavicular, calcaneocuboid) to differentiate isolated ankle pathology from pan-tarsal wear.
• Range of Motion: Measure passive and active sagittal ankle dorsiflexion and plantarflexion with the knee flexed and extended (Silfverskiöld test to evaluate gastrocnemius tightness). Lock the talus within the mortise to accurately evaluate isolated subtalar inversion and eversion.
• Neurovascular Assessment: Document distal pulses (dorsalis pedis and posterior tibial) and protective sensation (10-gauge 5.07 Semmes-Weinstein monofilament) to rule out peripheral neuropathy or Charcot arthropathy.

Investigations

• Weightbearing Radiographs: The diagnostic cornerstone comprises weightbearing anteroposterior (AP), mortise, and lateral views of the ankle, supplemented by full-length weightbearing Saltzman hindfoot views or long-leg alignment films if proximal malalignment exists. Findings include asymmetric joint space reduction, subchondral eburnation/cysts, and anterior or peripheral osteophytes.
• Weightbearing Computed Tomography (WBCT) / Conventional CT: Superior in demonstrating exact bone stock, talar osteonecrosis, cyst formation, coronal tilt, and occult adjacent joint arthrosis (especially subtalar).
• Magnetic Resonance Imaging (MRI): Useful when assessing talar dome avascular necrosis, early osteochondral lesions, or soft-tissue pathology, though less critical in advanced end-stage osteoarthrosis.
• Diagnostic Injections: Image-guided (ultrasound or fluoroscopy) local anaesthetic injections into the tibiotalar joint assist in distinguishing symptoms arising from the talocrural joint versus adjacent subtalar or talonavicular arthrosis.

Management

Non-Operative Management

Indicated for early-to-moderate stages or in medically compromised patients unfit for surgery:

• Activity modification, weight optimization, and low-impact cross-training.
• Analgesia with paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), or topical agents.
• Orthoses: Stiff-soled shoes with a rocker-bottom modification facilitate smooth sagittal gait rollover. Rigid ankle-foot orthoses (AFOs) or Arizona-style leather gauntlets restrict tibiotalar movement.
• Intra-articular injections: Corticosteroid injections offer temporary symptomatic reduction; hyaluronic acid and platelet-rich plasma (PRP) have limited long-term evidence in end-stage disease.

Operative Management

When non-operative therapies fail, surgical strategies depend on joint preservation versus joint sacrifice.

Joint Preservation (Supramalleolar Osteotomy)

Considered in young patients with asymmetric joint wear (Takakura Stage II or IIIA), preserving a healthy articular portion by realigning the mechanical weightbearing axis via opening or closing wedge supramalleolar tibial osteotomies (often coupled with a fibular osteotomy).

Total Ankle Arthroplasty (TAA)

Indicated primarily in older patients (>60 years), low-impact functional demands, preserved bone stock, coronal deformity <10°–15°, and absent neuromuscular dysfunction. It provides preservation of sagittal motion and protects adjacent joints from accelerated wear, though registry data highlight higher revision rates than arthrodesis.

Ankle Arthrodesis

The gold standard for end-stage arthritis (post-traumatic, inflammatory, or infectious), high-demand manual laborers, severe coronal deformity (>15°), talar avascular necrosis, and Charcot neuroarthropathy.

Surgical Principles and Ideal Position

Solid bony union in the correct position is mandatory for a functional gait:

• Sagittal plane: Neutral dorsiflexion/plantarflexion (90° to the tibial shaft). Avoid plantarflexion (causes genu recurvatum and extensor strain) and excessive dorsiflexion (leads to excessive heel loading and calcaneal pain).
• Coronal plane: 0° to 5° of hindfoot valgus. Avoid varus, as it locks the transverse tarsal joints and creates a rigid, painful lateral column.
• Transverse plane: 5° to 10° of external rotation (symmetrical to the contralateral limb).
• Translation: Slight posterior translation of the talus (preserves normal hindfoot moment arm and eases forward rollover).

Surgical Approaches & Fixation Techniques

• Arthroscopic Arthrodesis: Indicated for minimal or correctable deformity (<10°–15° coronal plane tilt) with adequate bone stock. Benefits include shorter time to union, less soft-tissue devascularisation, lower wound breakdown rates, and decreased postoperative pain. Preparation involves complete articular cartilage removal down to bleeding subchondral bone with curettes and high-speed burrs, accompanied by subchondral microfracture/drilling.
• Open Anterior Approach: Utilised for severe deformity, significant anterior bone loss, or when anterior plate neutralization is selected. Dissection passes through the interval between tibialis anterior and extensor hallucis longus, mobilising and protecting the anterior neurovascular bundle laterally.
• Transfibular Approach: Excellent exposure for rigid coronal deformities and revisions. Requires an oblique fibular osteotomy (approximately 8–10 cm proximal to the ankle joint); the resected fibula can be split longitudinally, morcellised as autograft, or applied as an onlay lateral strut.
• Fixation Methods:
  • Crossed Cannulated Cancellous Screws: Standard technique utilizing 2 or 3 large-diameter (6.5–7.5 mm) partially threaded screws with compressive lag effect. A standard 3-screw construct comprises: (1) posterolateral distal tibia into talar neck; (2) anteromedial distal tibia into talar body; and (3) home-run screw from lateral talus up into medial tibial metaphysis.
  • Anterior or Lateral Rigid Locking Plates: Provide enhanced torsional and cantilever bending stiffness, favored in osteopenic bone, revision scenarios, or substantial bony defects.
  • Retrograde Tibiotalocalcaneal (TTC) Intramedullary Nail: Indicated if severe combined ankle and subtalar pathology exists, profound talar collapse/AVN is present, or in Charcot neuropathic collapse.