Primary Flexor Tendon Repair Techniques

Abstract

Initially the strength of tendon repair depends only on the properties of the repair technique. Postoperatively tenomalacia may develop at the suture-tendon junction decreasing initial repair strength (7). With immobilization the strength of the tendon repair has been shown to decrease significantly within the first three weeks of healing (8). However, early passive (9) and especially early active motion (8, 10, 11) have been shown to prevent the initial weakening leading to progressively increasing repair strength starting from the time of repair. The initial strength of the repair depends on the material properties and knot security of the sutures as well as on the holding capacity of the suture grips of the tendon. The biomechanical properties of the suture depend on the material itself and can be improved by increasing the number of strands crossing the repair site (12) and the suture calibre (13, 14). The holding capacity of the repair of the tendon depends on the configuration (12, 15–17), size (18, 19), and number (20) of the grips. The flexor tendon repair can be regarded as a composite of the core and the peripheral sutures (21, 22) with both influencing significantly the repair strength. Lotz et al. (21) showed that in a repair consisting of the 2-strand modified Kessler 4-0 core suture and simple running 6-0 peripheral suture, the applied load was carried from 64% to 77% by the peripheral suture at its point of rupture. After failure of the peripheral suture the total force is transferred onto the core suture. If the holding capacity of the core suture is exceeded, but not its material strength, the repair may still increase in strength with concomitantly progressing gap formation (21, 23). Ultimate failure finally occurs either by suture pullout or, if the holding capacity of the suture grips of the tendon exceeds the material strength, by suture breakage (14, 23, 24). FLExOR TENDON FORCES