A Biomechanical Comparison of the LaPrade Technique Versus a Novel Technique for Reconstruction of Medial-Sided Knee Injuries.

BACKGROUND: Medial-sided knee injuries can lead to symptomatic valgus laxity or anteromedial rotatory instability and may require surgery, particularly in the setting of cruciate tears and tibial-sided medial collateral ligament (MCL) avulsions. The LaPrade (LP) technique utilizes 2 free grafts to reconstruct the superficial MCL (sMCL) and the posterior oblique ligament (POL). An alternative MCL reconstruction devised by the senior author comprises an anatomic single-bundle reconstruction using a free graft to reconstruct the sMCL with advancement and imbrication of the posteromedial capsule/POL (MCL anatomic reconstruction with capsular imbrication [MARCI] technique). These techniques have not been biomechanically compared with one another. PURPOSE: To identify if one of these reconstruction techniques better restores valgus and rotational medial knee stability throughout the range of motion. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 20 fresh-frozen, male (mean age, 43.7 years [range, 20-63 years]), midfemur-to-toe-matched cadaveric knees were utilized. All reconstructions were performed by a single fellowship-trained sports medicine surgeon. Left and right specimens within matched pairs were randomized to 1 of the 2 treatment groups: LP or MARCI. Each specimen was tested in 3 phases: (1) intact knee, (2) destabilized (MCL and POL completely severed), and (3) reconstructed (post-LP or post-MARCI reconstruction). We quantified valgus angulation defined by medial joint line opening, as well as internal and external tibial rotation at 0°, 20°, 30°, 60°, and 90° of knee flexion under applied external moments/torques at each phase. RESULTS: There were significant differences between the MARCI and LP reconstruction groups in valgus stability compared with the intact state (P = .021), with the MARCI reconstruction more closely approximating the intact knee. There was no overall difference between the MARCI and LP reconstruction techniques for internal rotation (P = .163), with both closely resembling the intact state. For external rotation, the effect of the reconstruction technique was dependent on the knee flexion angle (P < .001). At the highest angles, there were no differences between reconstructions; however, for lower knee flexion angles, the MARCI technique more closely resembled the intact state. CONCLUSION: Although both techniques improved knee stability compared with destabilized conditions, the MARCI technique better approximated intact stability during valgus at knee flexion angles from 0° to 90° and external rotation loads at knee flexion angles ≤30° in a cadaveric model. CLINICAL RELEVANCE: The MARCI technique provides an alternative option to improve valgus stability throughout the range of motion. It utilizes a POL advancement without the potential limitations seen in the LP technique, such as multiple tunnel complexity and collision, particularly in the multiple ligament-injured knee.

No Significant Difference Between Intramedullary and Extramedullary Button Fixation for Distal Biceps Brachii Tendon Rupture After Cyclic Loading in a Cadaver Model.

PURPOSE: To biomechanically compare intramedullary (IM) versus extramedullary (EM) distal biceps button fixation under cyclic loading conditions, which is most representative of postoperative physiologic status. METHODS: This controlled laboratory study used 13 fresh-frozen matched paired cadaver elbows. One specimen from each pair was randomized to either IM (unicortical) or EM (bicortical) distal biceps button fixation via onlay technique. A servohydraulic actuator was used to cycle each specimen from full extension to 90° of flexion at 0.5 Hz for 3,000 cycles. All specimens were subsequently loaded to failure to simulate an acute postoperative load. RESULTS: During cyclic loading, the mean change in force from cycle 5 to cycle 3000 was 2.1 ± 3.2 N for the IM group and 0.6 ± 4.2 N for the EM group (P = .19). The increase in tendon gap for the IM group was 1.02 mm and for the EM group was 1.83 mm (P = .37). During failure loading, the IM group had a mean failure load of 154.9 ± 44.5 N and the EM group a mean failure load of 191.1 ± 62.6 N (P = .16). CONCLUSIONS: No significant differences exist between the IM and EM techniques in loss of force and tendon gap formation under cyclic loading or load to failure conditions. Thus, IM fixation may adequately facilitate optimal bone-tendon apposition, with less risk of iatrogenic injury to the posterior interosseous nerve that can be seen with bicortical extramedullary fixation. CLINICAL RELEVANCE: The most common major complication following distal biceps repair is PIN palsy. IM fixation may be sufficient in facilitating optimal bone-tendon apposition and healing with onlay technique, while minimizing risk of iatrogenic PIN injury associated with EM fixation.