A suture anchor-based repair technique for type IV jersey finger injuries: a biomechanical investigation

Abstract

The aim of this biomechanical investigation was to evaluate a repair technique for type IV FDP tendon avulsions using a suture anchor, addressing the bony and the tendinous aspect of this injury simultaneously. In 45 distal phalanges from human anatomical specimens the injury was simulated and repairs were performed with a suture anchor using an innovative technique, interosseous sutures and a combination of screws and an interosseous suture. Repetitive loading for 500 cycles simulated postoperative mobilization. Repairs were loaded to failure thereafter. Elongation of the tendon-suture complex, gap formation at the bone-bone contact line and at the bone-tendon insertion line, load at first noteworthy displacement (2 mm), load at failure and the mechanism of failure were assessed. The suture anchor technique was superior biomechanically considering load at failure (mean: 72.8 N), bony gap formation (mean: 0.1 mm) as well as tendinous gap formation (mean: 0.7 mm), implying a preferable stability of the repair. Overall, this study demonstrates good ex vivo mechanical stability for a proposed suture anchor repair technique for type IV FDP tendon avulsion injuries, which might enable early postoperative mobilization in patients. The technique's subcutaneous implant placement and low implant load are expected to reduce potential complications observed in other commonly used repair techniques. This approach warrants further evaluation in vivo.

Figure 1

(A) Specimen repaired with the suture anchor technique. Articular line alignment is visualized. (B) Illustration of the suture anchor technique depicting implant position, as well as the pattern of suture placement within the distal phalanx, the bony avulsion fragment and the tendon.

Figure 2

(A) Illustration of the interosseous suture reattachment of the bony and tendinous injury components. To allow a clear perception of the suture placement within the tendon and the avulsed bony fragment in the top view, dorsal aspects of the sutures are not depicted. (B) Photographic image of a specimen repaired with interosseous sutures.

Figure 3

(A) Type IV injury repair using minifragment screws for bony avulsion repair and an additional interosseous suture for tendon reattachment. (B) Specimen after repair with screws and an interosseous suture. (C) Lateral fluoroscopy image of the distal phalanx after avulsion fragment repair with screws.

Figure 4

(A) Specimen preparation and injury simulation prior to repair. (B) Repaired specimen secured in the DP holding cylinder mounted on the tensile testing machine. Distance (r) indicating the 10 mm reference for further image evaluation.

Figure 5

Exemplary load versus displacement curve-graphs for each particular repair technique. The circle marks the point of measurement of the “load at the first noteworthy displacement (2 mm)”. The triangle indicates the “load at failure” assessment point.