BIOMECHANICAL ANALYSIS OF 4-STRAND EXTENSOR TENDON REPAIR TECHNIQUES

Experience with flexor tendon repairs has suggested the superiority of the augmented Becker (MGH) technique for strength, toughness, and gap resistance. In an effort to apply these findings to the extensor tend ons, 3 four-strand extensor tendon repair techniques were biomechanica lly tested in fresh human cadaver limbs: modified Bunnell, modified Kr ackow-Thomas, and MCH. Repairs were performed in Verdan's zone VI. Rep aired tendons were distracted at constant speed until rupture. Tendon load and tendon distraction were continuously monitored. Benchmark val ues for load were measured as fingers were pulled from full metacarpop halangeal (MP) joint flexion to full extension, to 1-mm gap formation at the tenorrhaphy, and to complete rupture of the repair. The MCH rep air proved significantly more resistant to gap formation (stronger and tougher) than the Bunnell and Krackow-Thomas repairs (p<.02). No diff erences were seen between groups in repair performance at MP joint ext ension and at complete rupture. This study suggests that the MGH techn ique has superior gap resistance to the other four-strand methods test ed for extensor tendon repair in Verdan's zone VI. The MGH repair is r ecommended for extensor tendon repairs in zone VI when early postopera tive motion regimens are considered.