Intramedullary Button Repair of Distal Biceps Ruptures: A Pilot Study
Reed Hoyer, MD; Alexander D. Choo, MD
Indiana Hand to Shoulder Center, Indianapolis, IN
Introduction: Distal biceps ruptures often require surgical repair and occur most commonly in middle aged males. Far-cortical suspensory button repair is a common surgical technique for repair, but risks the posterior interosseous nerve injury which can result in a wrist drop. Intramedullary button repair of distal biceps ruptures would decrease the neurovascular risk from far-cortical button placement.
Methods: Nine (9) fresh frozen cadavers were used for this study. The distal biceps muscle, tendon and proximal radius were removed from the cadaver, the distal biceps tendon was then tenotomized from its insertion on the radial tuberosity. The distal biceps tendon was then sutured and repaired to the radial tuberosity with an intramedullary button fixation. This fixation construct was then tested for visible gapping under cyclical load and then load to ultimate failure. The load to ultimate failure was then compared to historical controls.
Results: Of the nine specimens tested, 0/9 exhibited any appreciable gapping under cyclical load at 50 N with 1000 cycles tested. The mode of failure was button pulling out of bone (4/9), specimen gapping at interface (2/9), suture failure (2/9) and failure at musculotendinous junction (1/9). Pullout data was available for 6 of 9 specimens with an average pullout failure load of 244.4 N +/- 146.7. Comparison to prior historical control for endobutton repair of 274.8 +/- 95.6 for 11 specimens and suture anchor repair 230.1 +/- 86.5 demonstrates no statistical difference (p=0.613 for endobutton repair and p=0.801 for suture anchor repair).
Discussion: Intramedullary button repair for distal biceps repair resulted in no visible gap after 1000 cycles of cyclical load of 50 N. Load to failure strength of intramedullary button fixation was not significantly different compared to historical controls of far-cortical button and suture anchor fixation. Further studies are necessarily but intramedullary button fixation may be a reasonable method of fixation for these injuries.
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