MORTON S NEUROMA 80% III web space (next common is II). Never occurs in III or IV Common in females in fifties Aetiology: Pressure of Distal intermetatarsal ligament against common digital nerve Rule out Tarsal tunnel syndrome Lumbar radiculopathy Instability MTPJ joint or inflammatory MPJ Clinical 80% III web space (next common is II). Never occurs in III or IV Vague symptoms May complain of lateral ankle pain due to abnormal gait Symptoms more on weight bearing and more on heeled shoes Mulder s click is positive in 40% of case Numbness 30% Radiating pain 35% Sensation testing is variable Diagnostic Test: Local anaesthesia in the web space + steroid Electro diagnostic test is not useful in Morton s neuroma. Ultrasound; MRI may be helpful but usually not required X Ray usually normal Pathology Fusiform enlargement of the common digital nerve Immediate distal to edge of intermetatarsal ligament Perineural fibrosis with Renault bodies[are dense whorls of collagen] Limited inflammatory cells. No granuloma Non operative Metatarsal pad Shoe modification NSAID Local steroid 50 to 80% fail Surgery: 80% good results Dorsal approach All surgical candidates should be counselled preoperatively with regard to the general risks of foot surgery and the possibility of developing a symptomatic
neuroma, and warned that there will be permanent numbness in the affected web space. Procedure 3 cm dorsal incision centered over the interspace Divide the transverse metatarsal ligament Blunt dissection Common digital Nerve proximal to bifurcation Divide proximal and after the bifurcation Hard sole foot Plantar approach Longitudinal incision over the intemetatarsal space Divide the skin and fat Identify the nerve till its division Identify the neuroma Excise neuroma with it s two distal branches
SESAMOIDES Resemblance to sesame seeds Most constant sesamoids are those under 1st MTP joint Develop by endochondral ossification Ossification by age 8 12 yrs of age, females earlier Fibular sesamoid rarely partite Tibial sesamoid bipartite in 10% of population, a quarter of whom have bilateral bipartite tibial sesamoid The sesamoids are embedded in the plantar plate with attached to proximal phalanx via insertions of medial and lateral heads of FHB. The fibular sesamoid also attached to adductor hallucis, and intermetatarsal ligament. The tibial sesamoid is attached to abductor hallucis Biomechanics Mechanical protection for flexor hallucis longus tendon A pulley function promoting plantarflexion by flexor hallucis brevis Dispersal of the forces from the 1st metatarsal head X ray Bone Scan CT
ACUTE SESAMOID FRACTURE D/D partite sesamoids: look for a sharp lin fragments. A dorsiflexion views may show increase in separation of CT scan may help. Treatment Below knee cast for 3 weeks, followed by a metatarsal bar. Pain may persist for 4 6 months. If symptomatic non union, or chronic pain: consider excision of sesamoid or fragments, through medial or dorsal or plantar incision. Never excise both sesamoids as this produces a cock up deformity TURF TOE Exaggerated dorsiflexion with valgus/ varus strain of MTP joint More common since artificial sports surfaces Can range from sprains of the sesamoid complex to ruptures of the complex causing proximal or distal migration of the sesamoid bones to sesamoid complex to a fracture of the sesamoid and dislocation Usually treated with below knee cast, but may need operative reduction and repair through medial approach
FOOT TUMOURS Commonest sarcoma: Synovial sarcoma Common benign bone tumours in foot: SBC, Calcified lipoma, GCT and Osteoid Osteoma Fibromatosis: Asymptomatic leave it alone Symptomatic wide excision Recurrence wide excision with skin graft Possible bone sarcoma: Osteosarcoma Ewing s sarcoma Subungual exostoses