Double intramedullary cortical button versus suture anchors for distal biceps tendon repair: a biomechanical comparison

Purpose: The aim of this biomechanical in vitro study was to compare the novel technique of double intramedullary cortical button (DICB) fixation with the well-established method of suture anchor (SA) fixation for distal biceps tendon repair. Methods: A matched-pair analysis (24 human cadaveric radii) was performed with respect to cyclic loadings and failure strengths. Twelve specimens per group were cyclically loaded for 1,000 cycles at 1.5 Hz from 5 to 50 N and from 5 to 100 N, respectively. The tendon–bone displacement was optically analysed using the Image J Software (National Institute of Health). Afterwards, all specimens were pulled to failure. Maximum load to failure and mode of failure were recorded. Results: All DICB constructs passed the cyclic loading test, whereas 4 of the 12 specimens within the SA group failed by anchor pull-out. Cyclic loading showed a mean tendon–bone displacement of 0.6 ± 1.4 mm for the DICB group and 1.4 ± 1.4 mm for the SA group (n.s.) after 1,000 cycles with 50 N, and a mean displacement of 2.1 ± 2.4 mm for the DICB group and 3.5 ± 3.7 mm for the SA group (n.s.) after 1,000 cycles with 100 N. Load to failure testing showed a mean failure load of 312 ± 76 N and a stiffness of 67.1 ± 11.7 N/mm for the DICB technique. The mean load to failure for the SA repair was 200 ± 120 N (n.s.) and the stiffness was 55.9 ± 21.3 N/mm (n.s.). Conclusions: The novel technique of DICB fixation showed small tendon–bone displacement during cyclic testing and reliable fixation strength to the bone in load to failure. Moreover, all DICB constructs passed cyclic loadings without failure. Based on the current findings, a more aggressive postoperative rehabilitation may be allowed for the DICB repair in clinical use.