Ankle & Midfoot OA

Patients describe activity-related pain - the cardinal symptom - worse with weight-bearing, walking, prolonged standing, and uneven ground, improving with rest. Morning stiffness is typically less than 30 minutes (contrast with inflammatory arthritis where stiffness exceeds 30 minutes). Intermittent activity-related swelling, reduced range of motion (particularly dorsiflexion in ankle OA), and difficulty on uneven ground from loss of subtalar and midfoot motion are common. Anterior ankle catching at extremes of dorsiflexion from osteophyte impingement may be the earliest symptom of ankle OA. Always ask about previous ankle fracture, recurrent sprains, midfoot sprains, inflammatory arthritis symptoms, gout, and diabetes (Charcot risk).

Examination:

• •Gait: antalgic, loss of push-off power, altered foot position
• •Standing assessment: hindfoot alignment from behind, arch height, too many toes sign
• •Ankle joint: anterior joint line tenderness, palpable osteophytes, dorsiflexion and plantarflexion range, effusion, crepitus
• •Subtalar and talonavicular joints: inversion and eversion are restricted and painful in talonavicular OA; palpate the talonavicular joint dorsomedially
• •Midfoot (TMT and NC joints): dorsal tenderness and prominence, mobility
• •Stability: anterior drawer, talar tilt (post-traumatic instability often coexists)
• •Gastrocnemius and Achilles tightness on Silfverskiold testing
• •Neurovascular assessment, particularly sensation in diabetic patients (Charcot risk)

Red flags: hot, red, swollen foot in a diabetic patient (Charcot until proven otherwise - urgent offloading and specialist assessment); acute hot swollen joint (exclude septic arthritis and crystal arthropathy); rapidly progressive deformity; night pain or weight loss; persistent midfoot pain after significant trauma (missed Lisfranc).

Per NICE NG226 principles OA can often be diagnosed clinically. However, weight-bearing radiographs are particularly useful in foot and ankle OA because alignment, deformity, and post-traumatic change influence management.

Plain radiographs must be weight-bearing. For the ankle: AP, lateral, and mortise views. Look for joint space narrowing, subchondral sclerosis, osteophytes (anterior tibial and talar osteophytes are common and early), subchondral cysts, loose bodies, talar tilt, and previous fixation hardware. For the midfoot: weight-bearing AP, lateral, and oblique views assessing TMT and NC joint space, dorsal osteophytes, malalignment, chondrocalcinosis, and Lisfranc malalignment (diastasis between the 1st and 2nd metatarsal bases).

CT is used for detailed bony assessment, subtle Lisfranc malalignment, osteochondral lesions, and pre-operative planning. MRI is reserved for suspected osteochondral lesions, early OA with normal X-ray, inflammatory synovitis, AVN, or soft tissue pathology. USS may demonstrate effusion, synovitis, and osteophytes and can guide injection. Bloods are not routine; consider them when inflammatory arthritis, gout, Charcot, or haemochromatosis is suspected.

Management follows NICE NG226 principles. Conservative care is first-line.

Core NICE NG226 treatments are therapeutic exercise (the most important), weight management when appropriate, and information and support. Exercise should target the calf, peroneals, intrinsic foot muscles, hip, and core; aquatic exercise is particularly valuable for ankle OA. Rocker-bottom shoes reduce dorsiflexion demand at push-off and are one of the most effective interventions for ankle OA; stiff-soled shoes reduce midfoot motion. Orthoses (custom insoles, medial-posted insoles for talonavicular OA with hindfoot valgus, AFO for severe ankle OA) are reserved for selected patients with instability, deformity, or abnormal loading - NICE NG226 does not recommend routine use for all OA.

Pharmacological options per NICE NG226: consider topical NSAIDs for ankle and midfoot OA (consider, not offer, for non-knee joints); oral NSAIDs at the lowest effective dose and shortest duration if topical insufficient, with gastroprotection where needed. Do not routinely offer paracetamol, glucosamine, hyaluronan, or strong opioids. Intra-articular corticosteroid injection (USS or fluoroscopy-guided) provides short-term relief and is also diagnostically useful.

Surgical options when conservative care fails:

• •Joint-sparing procedures earlier in disease: arthroscopic debridement of osteophytes for anterior impingement with preserved joint space; corrective osteotomy for malalignment
• •Arthrodesis (fusion) is the most established procedure for end-stage ankle or midfoot OA. Ankle arthrodesis provides reliable pain relief but eliminates motion, and adjacent joint OA (subtalar, talonavicular) is a recognised long-term consequence. Talonavicular fusion is used for predominant talonavicular OA; Lapidus for the 1st TMT; triple arthrodesis for multijoint hindfoot or midfoot OA
• •Total ankle replacement (TAR) is an important alternative that preserves motion. Modern 3rd-generation designs have improved survivorship; selection requires good bone stock, correctable alignment, and lower-demand activity. NICE IPG509 supports TAR. The choice between TAR and arthrodesis is individualised through shared decision-making

Refer to an orthopaedic foot and ankle specialist if conservative care fails, deformity is progressing, or surgical options are being considered. Refer to rheumatology if inflammatory arthritis is suspected. Urgent referral is required for a diabetic patient with a hot swollen foot to exclude Charcot.

Rehabilitation follows NICE NG226 principles - exercise, footwear, selective orthoses, and activity modification.

• •Core exercises: calf strengthening (soleus and gastrocnemius - single-leg heel raises progressing to weighted), peroneal strengthening (resisted eversion), intrinsic foot strengthening (short-foot exercise, towel scrunches), tibialis posterior strengthening, hip abductor and core work
• •Range of motion: ankle dorsiflexion stretching, subtalar mobility, midfoot mobility. Maintaining available motion slows functional decline
• •Aquatic exercise: particularly valuable - strengthening and cardiovascular fitness with reduced joint loading
• •Balance and proprioception: important in post-traumatic OA where ligamentous insufficiency often coexists
• •Activity modification: cycling, swimming, elliptical. Modify sport rather than cease activity
• •Footwear and orthoses: ongoing rocker-bottom shoes for ankle OA, stiff-soled shoes for midfoot OA, custom insoles and AFO where appropriate. Often long-term

Post-arthrodesis pathway: 0 to 6 weeks non-weight-bearing in a cast or boot with proximal strengthening; 6 to 12 weeks progressive weight-bearing and gentle adjacent-joint range; from 12 weeks transition to supportive footwear (often permanently), gait retraining, and long-term rocker-bottom shoes or custom orthoses.

Post-TAR pathway: 0 to 6 weeks protected weight-bearing with anterior wound vigilance and gentle ankle range when permitted; 6 to 12 weeks progressive weight-bearing, active range, and strengthening; from 12 weeks progressive functional rehabilitation with avoidance of long-term high-impact loading to protect the implant.

• •NICE NG226 - therapeutic exercise is the most important core treatment; consider topical NSAIDs for non-knee joints; do not routinely offer paracetamol, glucosamine, hyaluronan, or strong opioids.
• •NICE IPG509 - supports total ankle replacement as an alternative to arthrodesis in selected patients with good bone stock and correctable alignment.
• •BOFAS UK consensus - ankle arthrodesis remains the most established procedure for end-stage ankle OA; adjacent joint OA is a recognised long-term consequence.
• •Saltzman et al. (Iowa Orthop J 2005) - established the predominantly post-traumatic aetiology of ankle OA, with only around 7 to 10 percent of cases primary, contrasting starkly with hip and knee OA.
• •BOFAS guidance on Charcot neuroarthropathy - urgent assessment and offloading required for any diabetic patient with a new hot, swollen, or rapidly deforming foot.

• •Ankle OA is predominantly POST-TRAUMATIC - the key distinguishing feature from hip and knee OA. Always ask about previous fracture, recurrent sprains, or osteochondral injury.
• •The talonavicular joint contributes approximately 80 percent of hindfoot inversion and eversion - OA here significantly restricts foot adaptability.
• •Midfoot OA after a midfoot sprain that never fully recovered should raise suspicion of a missed Lisfranc injury.
• •Weight-bearing radiographs are essential - non-weight-bearing views underestimate deformity. Anterior tibial or talar osteophytes may be the earliest sign of ankle OA.
• •Per NICE NG226: therapeutic exercise is the core treatment; consider topical NSAIDs for non-knee joints; do not routinely offer paracetamol, glucosamine, hyaluronan, or strong opioids; orthoses are for selected patients only.
• •Ankle arthrodesis is the most established procedure for end-stage disease; TAR (NICE IPG509) is the alternative that preserves motion. Hot swollen foot in a diabetic patient is urgent Charcot assessment.