Biomechanics of a Scapholunate Bridge Augmentation Technique Using All-Suture, Knotless Anchors

To assess scapholunate bridge augmentation with all-suture, knotless anchors in cadaveric wrists through evaluation of radiographic parameters, by comparing the bridged wrist to the wrist with an intact scapholunate interosseous ligament (SLIL) and sectioned SLIL.

Nine cadaveric specimens were tested in 6 positions: wrist flexion, extension, ulnar deviation (UD), radial deviation (RD), clenched fist, and neutral. Radiographic parameters including scapholunate interval (SLI), scapholunate angle (SLA), and dorsal scaphoid translation (DST) were measured for each position. The SLIL was then sectioned, and parameters were measured in all 6 positions. The SLIL was repaired using one knotless anchor in the scaphoid and one in the lunate, with the repair suture from each anchor shuttled into the opposing anchor and tensioned to bridge the interval. Parameters were again measured in the 6 positions. Scapholunate interval was evaluated using repeated measures analysis of variance at α = 0.05; descriptive statistics were performed for SLA and DST.

Scapholunate interval was different between testing states in flexion (P < .001), UD (P < .001), RD (P = .01), clenched fist (P < .001), and neutral (P = .02). Post hoc testing revealed SLI was wider in the sectioned state than the intact state and bridged states in flexion, UD, and clenched fist. Scapholunate interval in these 3 states was similar between intact and bridged states. In neutral, SLI was narrower in the bridged state compared with intact and sectioned states. In RD, SLI was narrower in the bridged state compared with the sectioned state. Abnormal SLA (>60°) was only seen in flexion, across all 3 states. Mean DST increased after sectioning, then decreased after bridging, in extension, UD, RD, clenched fist, and neutral, although statistical conclusions cannot be drawn.

Scapholunate bridge augmentation restored radiographic parameters of carpal alignment.

With further cadaveric testing followed by clinical study, this technique may prove to be a useful treatment for SLIL injury.