Definition
Disorder of immune system
- antigen-antibody complexes
- stimulate release of proteolytic enzymes
- leading to vasculitis, synovitis and cartilage destruction
Epidemiology
90% will have foot problems, most commonly forefoot
Pathology
| Forefoot | Midfoot | Hindfoot |
|---|---|---|
|
Hallux Valgus / Rigidus Dorsal subluxation MTPJ Clawing of toes |
TNJ OA |
Planovalgus - tibialis posterior rupture - synovitis subtalar joint |
| Ankle joint rarely affected in isolation |
Forefoot
Hallux valgus / Hallux rigidis / MTPJ dislocation / claw toes
Pathology
Synovitis of MTPJ with capsular destruction
- dorsal subluxation MTPJ
- claw toes develop (MTPJ hyperextended, PIPJ flexed)
- plantar fat pad displaced distally and metatarsal heads exposed to plantar skin
Non-operative Management
Shoe-wear modification - roomy toe box, premetarsal dome
Operative Management
Issues
Poor wound healing / infection / non-union / recurrence
Hallux Valgus / Rigidus
Options
Arthrodesis / Arthroplasty / Keller's procedure
Metarsalgia
Options
Synovectomy / Weil's osteotomy / Fowler's procedure
Concept
Cascading excision of II - V MT heads
- 2nd 3 mm longer than 1st or 3rd
- 3rd 3mm longer than 4th
- 4th 3 mm longer than 5th
Technique
Single dorsal transverse skin excision just proximal to toe webs
- can be performed via transverse plantar ellipse
- with severe dislocation may be easier to approach through plantar aspect
- MT heads subcutaneous & NV bundle usually subluxed dorsally
Extensor tenotomy
MT heads excised in gentle curve
- dorsal distal to plantar proximal
- contoured on plantar surface to give rounded surface
- very little length removed from 5th MT
- must not leave bony fragments in weight bearing pad
Second incision on plantar surface
- proximal to MT heads
- ellipse of skin only excised
- closed to pull skin of forefoot under MT ends
Claw toes
EPL lengthening / EDB tenotomy / PIPJ fusion
Midfoot
Tarsometatarsal osteoarthrtis
Midfoot fusion
TNJ osteoarthritis
Talonavicular Arthrodesis
Indication
- erosion confined to this joint
- correct valgus deformity
Technique
- dorsomedial incision
- protect saphenous nerve and vein
Result
- will lose 80% STJ motion
Hindfoot
Tendo Achilles Insertional Tendonitis
Rheumatoid involvement of bursa at T Achilles insertion
- nodules may develop within the tendon
- can weaken attachment & precipitate rupture
Treatment
- excision of nodules
- may need tendon augmentation / reconstruction
Retrocalcaneal Bursitis
Common
- heel lift initially
- may need debridement and excision of posterosuperior calcaneal prominence
Tibialis Posterior Tendonitis / Rupture
Synovitis of sheaths of T post & Peroneal tendons common
- treat with tenosynovectomy
Rupture of TP with flatfoot
- FDL transfer in Stage 2
- triple arthrodesis in Stage 3
- pan talar arthrodesis in Stage 4
Planovalgus
Causes
- STJ OA
- TNJ OA
- tibialis posterior rupture
- synovitis and rupture of the talocalcaneal interosseous ligament
- tight T Achilles
Pathology
- subtalar joint valgus angulation
- talar head drops into plantarflexion
- navicular subluxes laterally
- get planovalgus foot with forefoot abduction
Non Operative
Brace
- double upright with square ferrule
Operative
Triple Arthrodesis
Indication
- fixed painful hindfoot
- TNJ and STJ OA
- AKJ preserved
AKJ OA
Total Ankle Replacement
Attractive concept
- reduces loading across other joints
- results similar to OA
Ankle Arthrodesis
Treatment of choice
Complicated by
- prolonged period to union - 6/12
- non-union in 10%