Medial Patellofemoral Ligament Reconstruction: Impact of Knee Flexion Angle During Graft Fixation on Dynamic Patellofemoral Contact Pressure-A Biomechanical Study.

PURPOSE: Objective evaluation of the optimal graft tension angle to fully restore patellofemoral contact pressure in reconstruction of the medial patellofemoral ligament (MPFL) in comparison to the native knee. METHODS: Twelve cadaveric knee specimens were fixed in a custom-made fixation device. A sensitive pressure film (Tekscan) was fixed in the patellofemoral joint, and patellofemoral contact pressure was assessed during a dynamic flexion movement from 0° to 90°. The MPFL was cut and measurements were repeated. Reconstruction of the MPFL was performed with the gracilis tendon subsequently fixed in the femur at 15°, 30°, 45°, 60°, 75°, and 90° of knee flexion under controlled tension (2 N). The sequence of the flexion angles was alternated. Pressure measurements were repeated after every fixation of the graft. RESULTS: No significant differences were seen in the overall patellofemoral contact pressure compared to the native knee (P > .05). However, medial patellofemoral pressure showed a significant increased patellofemoral contact pressure after MPFL reconstruction at a knee flexion angle during graft fixation of 15° (P = .027), 45° (P = .050, P = .044), and 75° (P = .039). Moreover, proximal/distal patellofemoral contact pressure revealed a significantly reduced contact pressure at 15° (P = .003), 30° (P = .009), 45° (P = .025), 75° (P = .021), and 90° (P = .022) of flexion distal after MPFL reconstruction compared with the intact knee. Lateral patellofemoral contact pressure was significantly reduced in all performed reconstructions (P < .05). CONCLUSIONS: The flexion angle during graft fixation for MPFL reconstruction did not have a significant impact on the overall patellofemoral contact pressure. However, selective medial, proximal, distal, and lateral patellofemoral contact pressure was significantly altered for all reconstructions. Fixation of the MPFL graft at 60° of flexion was able to most closely restore patellofemoral contact pressure compared with the intact knee. CLINICAL RELEVANCE: Based on the findings of the present study, fixation of the graft in anatomic reconstruction of the MPFL should be considered in 60° of flexion under low tension (2 N) to most closely restore patellofemoral contact pressure compared with the native knee.

[Ligamentous elbow injuries-When is surgical treatment still indicated?] / Ligamentäre Ellenbogenverletzung ­ Wann ist die operative Therapie noch indiziert?

The elbow joint is a hinge-type synovial joint and is the second most frequently dislocated joint in adults and the most frequently dislocated joint in children. To find the right treatment options a precise understanding of the injury pattern, anatomy, biomechanics and pathology (simple vs. complex dislocation) is essential for a good reconstruction of the function and to prevent chronic instability and pain. The differentiation between acute and chronic instability gives another variation in the treatment plan. According to the latest literature there are clear indications for surgery of a complex elbow dislocation, whereas for simple dislocations conservative treatment is preferentially recommended; however, when is the surgical treatment of a ligamentous elbow dislocation (still) indicated?