Pretensioning of quadruple flexor tendon grafts in two types of femoral fixation: quasi-randomised controlled pilot study

Abstract

Pretensioning of the flexor tendon graft of the knee is used to improve the stability of anterior cruciate ligament (ACL) reconstructions. The objective was to demonstrate the pretensioning of grafts of the semitendinosus and gracilis in situ with range of flexion and extension of 0-110°, and determine the appropriate number of cycles in two types of femoral fixation. ACL reconstruction was performed in 60 patients, aged 16-48 years, 90% male, with 50% right knees and 50% left knees, divided into two groups of 30 patients: One with the femur fixed using interference screws (direct form) and the other with the transcondylar cross-pin screw (from a distance). Total length of the grafts, their circumference and the measurements on the radiographs of length of the grafts submitted to pretensioning and the measurements with ten, 25 and 50 cycles of flexion and extension were determined. There was no significant difference in relation to the total tendon lengths and their circumferences. The lengths of the portions submitted to pretensioning were significantly different: 7.90 cm for the interference and 10.92 cm for the transcondylar (mean). After tensioning, in the interference and transcondylar groups, respectively, lengthening was 3.57 mm/3.97 mm with ten, 6.30 mm/7.03 mm with 25, and 6.83 mm/7.7 mm with 50 cycles. The greater the length of the graft, the greater the lengthening on pretensioning throughout the substance; the shorter the length, the earlier the end of the lengthening was achieved, close to 25 cycles; more than ten cycles were necessary, 25 being sufficient.