Bicortical suspensory button fixation yields greater ultimate load to failure over unicortical all-suture anchor fixation in distal biceps brachii tendon repair

Background: Various distal biceps tendon repair techniques exist, each with their own biomechanical profile. Recently, all-suture an-chor fixation has recently become an intriguing option for distal biceps fixation, compared with the proven track record of the suspen-sory cortical button. In addition, intramedullary techniques have been utilized as a means to avoid complications such as nerve damage seen with extramedullary fixation.Purpose: The purpose of this study is to perform a comparative biomechanical analysis of 4 unique distal biceps tendon fixation methods: Unicortical/intramedullary all-suture anchor fixation (UIAS), Bicortical/extramedullary all-suture anchor fixation (BEAS), Unicortical/intramedullary suspensory button fixation (UISB), and Bicortical/extramedullary suspensory button fixation (BESB).Study Design: Controlled Laboratory study.Methods: 24 fresh-frozen cadaveric elbows were randomized into 4 groups providing data from 6 specimens, with each group under -going a different repair technique. The specimens underwent 2 studies: Cyclic loading and Ultimate Load to failure (ULTF) testing. The repaired elbows were cycled 3000 times between 0 and 90 degrees of flexion, with displacement under cyclic loading at the repair site measured using a differential variable reductance transducer. ULTF test was performed with the elbow flexed at 90 degrees. The modes of failure were recorded.Results: The mean cyclic displacements between the 4 groups were as follows: UIAS: 1.45 +/- 1.04 mm; BEAS: 2.75 +/- 1.32 mm; UISB: 1.45 +/- .776 mm; BESB: 2.66 +/- 1.18 mm (p= 0.077). Bicortical repairs displayed greater displacement after cyclic loading when compared with unicortical repairs regardless of anchor used (p= 0.007). The mean ULTF for each group was as follows: all-suture intramedullary: 200 N; all-suture extramedullary: 330 N; cortical-button intramedullary: 256 N; cortical-button extramedullary: 342 N). All-suture unicortical/intramedullary repair had a significantly lower ULTF (200 N) compared with cortical-button Bicortical/extrame-dullary repair (342 N) (p=0.043).Conclusion: Bicortical/extramedullary suspensory button fixation demonstrated a greater ultimate load to failure when compared with unicortical/intramedullary all-suture anchor fixation. These findings suggest that bicortical/extramedullary suspensory cortical button fixation is a biomechanically superior construct as compared to unicortical/intramedullary all-suture anchor fixation. However, there was no significant difference in ULTF between extra-medullary, Bicortical button or Bicortical, all-suture anchor fixation. Level of evidence: Basic Science Study; Biomechanics (c) 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.