Structural change of soft tissue anterior cruciate ligament reconstructions with cross-pin fixation between immediate and postoperative 8 weeks: a study with use of magnetic resonance imaging.

摘要

BACKGROUND: There is some controversy regarding the optional method for proximal fixation in anterior cruciate ligament reconstruction surgery using soft tissue grafts. Concern about the strength of fixation has limited rehabilitation during the early postoperative period. HYPOTHESIS: Graft slippage occurs after cross-pin femoral fixation during the early healing period when the strength of the tendon-to-bone interface is lowest. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Coronal and sagittal T2-weighted magnetic resonance images of arthroscopically reconstructed anterior cruciate ligaments performed in 18 consecutive knees were evaluated. The images were taken along the tunnel direction an average of 4 days (after the hemovac removal) and 8 weeks (recovery >120 degrees range of motion) after surgery. The distance was measured from the uppermost point of the graft to the upper border of the superior cross pin. To reduce the intra- and interobserver bias, the measurements were taken twiceby 2 orthopaedic surgeons for all patients. RESULTS: Interrater and intrarater reliability were determined twice by 2 orthopaedic surgeons. The intrarater (0.88 and 0.93) and interrater (0.79 and 0.81) agreement ranged from 0.79 to 0.93. One of the 18 patients showed complete breakage of the 2 cross pins 8 weeks after surgery, even though the pins were intact 4 days postoperatively. From an analysis of the remaining 17 patients, there was no significant difference in the coronal and sagittal measurements taken at postoperative 4 days and 8 weeks (P = .170-.737) and all individual cases showed less than 3 mm slippage. CONCLUSION: The expansion mechanism of the cross pin works well during the early healing period. However, further studies on the long-term outcomes are required. In addition, further study on the strength of this fixation technique is needed because 1 of the 18 patients showed broken pins.