Comparative study of the use of prefabricated bone tendon grafts and conventional tendon grafts in flexor tendon reconstruction

The prefabrication of a bone graft in a rat model

The prefabrication of bone grafts in a rat model was investigated. In 26 Sprague-Dawley rats, free iliac crest bone graft was harvested, bivalved, and reinserted heterotopically into the groin, where it was closed around the mobilized superficial inferior epigastric vascular bundle. In half the animals, the vascular bundle remained in continuity as a flow-through pedicle (group 1); in the remaining animals, the pedicle was ligated and divided distal to the bone graft. All grafts were isolated from other tissues by a silicone sheet envelope. At 3 or 6 weeks, the grafts were re-explored and analyzed by India ink perfusion and histologic examination for evidence of viability and neovascularization. Three weeks after insertion, India ink perfusion of the group 1 and 2 grafts revealed neovascularization extending to the periphery of the graft, and histologic examination showed extensive new bone formation on endosteal, periosteal, and trabecular surfaces of the graft. Six weeks after insertion, creeping substitution had almost completely remodelled the cortical and cancellous bone of both group 1 and 2 grafts to create a viable vascularized bone graft on a pedicle. In 3 control nonvascularized grafts (free iliac cortical bone without an implanted pedicle), all pre-existing bone of the graft was dead 3 weeks after insertion, and only very limited new bone formation was present within the graft.

Early active mobilization of tendon grafts using mesh reinforced suture techniques

The flexor digitorum profundus tendon in 11 digits with division of both flexor tendons in zone 2 was reconstructed with a palmaris longus tendon graft in a two-stage procedure. The distal and proximal fixation of the graft was reinforced with a polyester mesh sleeve placed around the ends of the graft during stage 1. All digits were mobilized with a combination of active extension and active and passive flexion within 3 days of the second stage. There were three ruptures, one due to faulty technique and two due to falls on outstretched hands during alcohol intoxication and football. Excluding the ruptures, the mean active composite distal and proximal interphalangeal joint range of motion 6 weeks and 6 months post-operatively was 141 degrees and 136 degrees respectively. The results indicate that palmaris longus tendon grafts can survive and heal during early active mobilization, with few or no adhesions of functional significance. The techniques described here represent one possible approach to the safe implementation of early active mobilization after tendon grafting procedures.

The plantaris tendon as a tendo-osseous graft. Part II. Clinical studies

To minimize adhesions following tendon repair, early post-operative movement is recommended. This has proved difficult with tendon grafting because of weakness of the repair sites, particularly distally, and because of slow revascularization. A potential solution is the use of a composite tendon-bone graft in which a bone block is attached to the end of the tendon. The tendon is threaded through a hole in the distal phalanx from the dorsal to the palmar side and impacted like a cork to create an immediate strong fixation. The tendon itself is then tunnelled through the pulley system and the proximal repair is carried out with a multiple weave technique which can withstand immediate active movement. The ideal tendon-bone complex is the plantaris attached to a segment of calcaneus. A preliminary report with two case studies is presented.

The plantaris tendon as a tendo-osseous graft. Part I. An anatomical study

Comparative studies have shown that bone-bone union develops faster than a junction between grafted tendon and bone, and would thus allow earlier post-operative movement, limiting adhesion formation. In this context the nature of the insertion of the plantaris tendon into the calcaneus is reviewed as a possible source of composite bone-tendon grafts. It is proposed that the composite plantaris tendon with its bony block attachment is inserted through a hole in the distal phalanx of the finger creating an immediate firm distal fixation. From cadaver dissections it was found that in at least 80% of cases the insertion of the plantaris tendon was directly into the calcaneus, independent of the tendo Achilles, and was therefore suitable for use as the proposed tendon graft.