Proximal Overresection During Femoral Osteochondroplasty Negatively Affects the Distractive Stability of the Hip Joint: A Cadaver Study.

BACKGROUND: Contact between the acetabular labrum and articular cartilage of the femoral head creates a suction seal that helps maintain stability of the femoral head in the acetabulum. A femoral osteochodroplasty may occasionally extend proximally into the femoral head, diminishing the articular surface area available for sealing contact. PURPOSE: To determine whether proximal overresection decreases the rotational and distractive stability of the hip joint. STUDY DESIGN: Controlled laboratory study. METHODS: Six hemipelvises in the following conditions were tested: intact, T-capsulotomy, osteochondroplasty to the physeal scar, and 5- and 10-mm proximal extension. The pelvis was secured to a metal plate, and the femur was potted and attached to a multiaxial hip jig. Specimens were axially distracted using a load from 0 to 150 N. For rotational stability testing, 5 N·m of internal and external torque was applied. Both tests were performed at different angles of flexion (0°, 15°, 30°, 60°, 90°). Displacement and rotation were recorded using a 3-dimensional motion tracking system. RESULTS: The T-capsulotomy decreased the distractive stability of the hip joint. A femoral osteochondroplasty up to the physeal scar did not seem to affect the distractive stability. However, a proximal extension of the resection by 5 and 10 mm increased axial instability at every angle of flexion tested, with the greatest increase observed at larger angles of flexion (P < .01). External rotation increased significantly after T-capsulotomy in smaller angles of flexion (0°, P = .01; 15°, P = .01; 30°, P = .03). Femoral osteochondroplasty did not create further external rotational instability, except when the resection was extended 10 mm proximally and the hip was in 90° of flexion (P = .04). CONCLUSION: This cadaveric study demonstrated that proximal extension of osteochondroplasty into the femoral head compromises the distractive stability of the hip joint but does not affect hip rotational stability. CLINICAL RELEVANCE: Clinically, this study highlights the importance of accuracy when performing femoral osteochondroplasty to minimize proximal extension that may increase iatrogenic instability of the hip joint.

Posterior Lateral Meniscal Root Tears Increase Strain on the Reconstructed Anterior Cruciate Ligament: A Cadaveric Study.

PURPOSE: To quantify the amount of strain across an anterior cruciate ligament reconstruction (ACLR) before and after a lateral meniscus (LM) posterior root complex tear and determine whether a meniscal root repair effectively protects the ACLR against excessive strain. METHODS: Fresh-frozen cadaveric knees were tested with an 88-N anterior drawer force and an internal and external torque of 5-Nm applied at 0°, 15°, 30°, 60°, and 90° of flexion. A simulated pivot shift was also applied at 0, 15, and 30° of flexion. Rotation and translation of the tibia, and strain across the ACL graft were recorded. Testing was repeated for the following four conditions: ACL-intact, ACLR with intact LM, ACLR with LM posterior root complex tear, and ACLR with root repair. RESULTS: The kinematic data from 12 fresh frozen cadaveric knees underwent analysis. Only 11 specimens had usable strain data. Sectioning the meniscofemoral ligaments and the LM posterior root increased rotational and translational laxity at 30° of knee flexion. ACLR graft strain significantly increased when an anterior load and internal torque were applied. Repair of the LM posterior root reduced strain when the knee was internally rotated but was unable to normalize strain when an anterior force was applied. CONCLUSIONS: This cadaveric biomechanical study suggests injury to the LM posterior root complex increases rotational and anterior laxity of the knee and places increased strain across reconstructed ACL grafts. Subsequent root repair did not result in a statistically significant reduction in strain. CLINICAL RELEVANCE: This study provides quantitative data on the implications of a LM posterior root injury in the setting of an ACL reconstruction to help guide clinical decision-making.

A Comparison of 3 Fixation Strategies in the Treatment of Neer Type IIB Distal Clavicle Fractures.

OBJECTIVES: To compare the stability of NT2B clavicle fractures fixed with either a hook plating (HP), Superior Plating with Suture Augmentation (SPSA), or dual orthogonal plating (DP) with the hypothesis that DP would provide increased multiplanar stability across NT2B fractures. METHODS: NT2B distal clavicle fractures were created in cadaveric specimens and fixed using (1) HP, (2) SPSA, or (3) DP. Specimens were cyclically loaded in 3 different planes of motion: (1) anteroposterior (AP), (2) superior-inferior, and (3) axial rotation while displacement was continually recorded. Afterward, a superiorly directed load was applied to the clavicle. Load to failure, stiffness, and mode of failure were recorded. RESULTS: During AP loading, clavicles fixed with a DP had significantly lower mean posterior displacement compared to those fixed with SPSA at every 100-cycle interval of testing, P < 0.01. During inferior-superior loading, specimens fixed with a DP had less superior displacement than specimens fixed with an HP and SPSA, reaching significance at the 500-700 cycles of testing. There was no significant difference in axial rotation stability or load to failure between the 3 fixation techniques. CONCLUSIONS: Orthogonally placed minifragment plates provide improved stability against anterior displacement with no significant difference in superior stability, axial rotational stability, stiffness, or load to failure. Further clinical studies are needed to confirm the long-term stability of dual plating and determine the risks and benefits of this novel method of distal clavicle fixation.

Biomechanical evaluation of PCL reconstruction with suture augmentation.

PURPOSE: The purpose of this study was to compare kinematics and patellofemoral contact pressures of all inside and transtibial single bundle PCL reconstructions and determine if suture augmentation further improves the biomechanics of either technique. METHODS: Cadaveric knees were tested with a posterior drawer force, and varus, valgus, internal and external moments at 30, 60, 90, and 120° of flexion. Displacement, rotation, and patellofemoral contact pressures were compared between: Intact, PCL-deficient, All-Inside PCL reconstruction with (AI-SA) and without (AI) suture augmentation, and transtibial PCL reconstruction with (TT-SA) and without (TT) suture augmentation. RESULTS: Sectioning the PCL increased posterior tibial translation (PTT) from intact at 60° to 120° of flexion, p < 0.001. AI PCL reconstruction improved stability from the deficient-state but had greater PTT than intact at 90° of flexion, p < 0.05. Adding suture augmentation to the AI reconstruction further reduced PTT to levels that were not statistically different from intact at all flexion angles. TT reconstructed knees had greater PTT than intact knees at 60, 90, and 120° of flexion, p < 0.01. Adding suture augmentation (TT-SA) improved posterior stability to PTT levels that were not statistically different from intact knees at 30, 60, and 120° of flexion. Patellofemoral pressures were highest in PCL-deficient knees at increased angles of flexion and were reduced after reconstruction, but this was not significant. CONCLUSION: In this time-zero study, both the all-inside and transtibial single bundle PCL reconstructions effectively reduce posterior translation from the deficient-PCL state. In addition, suture augmentation of both techniques provided further anterior-posterior stability.