Short-term outcome of unicortical, intramedullary repair of distal biceps ruptures – A retrospective cohort study

BACKGROUND: Modern distal biceps reconstruction techniques generally have satisfactory outcomes, but are not without complications. Posterior interosseous nerve (PIN) palsy is a rare but potentially devastating complication of bicortical metal button fixation. Recently, a unicortical, intramedullary, repair technique utilizing a suture anchor has been described. The primary aim of this study was to compare short-term functional and patient-reported outcomes and complication rates in patients receiving unicortical intramedullary repair (UR) with suture anchor against those receiving bicortical repair (BR) with metallic button. We hypothesized that UR would have equally satisfactory outcomes without the complication profile. METHODS: Retrospective chart review was conducted for all patients undergoing operative fixation of distal biceps tendon ruptures from 2015 to 2021 at our tertiary referral center. Twenty patients received BR, and eight patients received UR. Patient demographics and surgical complications were compared. QuickDASH scores at two-month and latest in-person and telehealth postoperative visits, as well as elbow and forearm range of motion at last clinical visit, were collected and analyzed. RESULTS: Average patient age in the BR & UR cohorts were 49.3 ± 9.3 and 42.1 ± 6.2 years, respectively, with a male predominance. There was no statistical difference in patient age, sex, hand dominance, injury laterality, injury chronicity, and follow-up duration. Range of motion was comparable and excellent in both groups. Latest follow-up was 3.0 ± 0.5 years in the BR and 1.5 ± 0.4 years in the UR cohorts. QuickDASH scores improved between the two-month and latest time points in each cohort however did not differ significantly in head-to-head comparison. Complications included a case of PIN palsy, distal biceps tendon rerupture, and lateral antebrachial cutaneous nerve (LABC) neuropraxia in the BR group and two cases of LABC neuropraxia in the UR group. The number needed to treat (NNT) for the prevention of one additional case of PIN palsy using UR is 22 patients. DISCUSSION: Short-term functional and patient-reported outcomes in traditional BR and newly reported UR of distal biceps tendon ruptures are comparable and excellent. UR did not have higher failure rate despite follow-up periods beyond what is typically reported for tendon reruptures. In this limited retrospective cohort study, UR also did not encounter postoperative PIN palsy and had an NNT of 22 patients. In the appropriate clinical setting, this provides early evidence supporting the utilization of unicortical intramedullary suture anchor fixation of distal biceps tendon ruptures as well as associated perioperative interventions such as preoperative nerve blocks.