Abstract
A dorsal incision is made over the metatarso-phalangeal joint (MTPJ) extending 2cm proximally and distally from the joint line. A routine cheilectomy of the MTPJ is performed. The Extensor digitorum longus (EDL) tendon is identified and divided through a separate incision 5 cm proximal to the MTPJ at the mid-foot level. A 3/0 vicryl stay suture is placed in the divided tendon. The tendon is retrieved from the distal wound and mobilised along with the extensor expansion and the dorsal capsule to expose the proximal half of the proximal phalanx. The transverse fibres of the extensor expansion and the MTPJ capsule are divided medially and laterally with preservation of the collateral ligaments. Extensor digitorum brevis is identified and protected. A groove is created on the dorsum of the proximal phalanx at the centre of the articular surface to stabilise the EDL tendon in its final position. A 3.2mm tunnel is then created at a 45 degree angle through the metatarsal neck beginning dorsally 2.5cm from the metatarsal articular surface and exiting just proximal to the plantar plate. The mobilised EDL tendon, expansion and capsule are then passed down through the MTPJ via a perforation in the plantar plate. The EDL tendon is then passed through the tunnel from plantar to dorsal where it is sutured to the periosteum of the metatarsal using a 3/0 vicryl suture. Hence the EDL tendon, expansion and dorsal capsule form an interposition arthroplasty.
Eleven patients with an average age of 37 years underwent the above procedure for Freiberg’s Disease or osteoarthritis of the second or third MTPJ. There were no intra-operative complications and at an average 31 month follow up 70% were pain free. We recommend the Cobb II procedure as a primary management option for MTPJ Freiberg’s Disease/osteoarthritis.
Correspondence should be addressed to: D. Singh, BOFAS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
