The incidence and significance of femoral tunnel widening after quadrupled hamstring anterior cruciate ligament reconstruction using femoral cross pin fixation☆

Abstract 

Purpose: The purpose of this study was to evaluate the amount of femoral tunnel widening that occurred after anterior cruciate ligament reconstruction using quadrupled hamstring autografts and to determine the clinical significance of any such tunnel enlargement. Type of Study: Retrospective clinical analysis. Methods: Twenty-nine patients who had undergone reconstruction of a torn anterior cruciate ligament with quadrupled hamstring autograft and cross pin femoral fixation were evaluated to determine the incidence and significance of postoperative femoral tunnel widening. A single surgeon performed all procedures, and average follow-up was 18.4 months (range, 12 to 31.5 months). All patients underwent flexion posteroanterior and lateral radiographs, an examination for determination of an International Knee Documentation Committee (IKDC) rating, had KT-1000 data collected, and completed Lysholm and Knee Outcome Survey functional questionnaires. Femoral tunnels were clearly seen in 27 patients. The tunnel diameters were measured at the opening of the tunnel, at the widest part of the tunnel, and just proximal to the cross pin. The amount of tunnel widening for each patient was then compared with the individual’s KT-1000 data, IKDC rating, and Lysholm and knee outcome survey scores to assess correlation. Results: Four different tunnel morphologies were noted, with the linear type being the most common. The widening at the greatest tunnel diameter was 65.5% on average. Side-to-side KT-1000 differences averaged 1.04 mm at 30 lb, and 1.10 mm at manual maximum. Eleven patients had IKDC overall ratings of normal, 13 had ratings that were nearly normal, and 2 had abnormal. Average Lysholm and knee outcome survey scores were 92.6 and 93.9, respectively. A significant correlation was found only between F2 and F3 widening with Lysholm scores. However, the significance was eliminated with removal of 2 outliers. Conclusions: The exact etiology of postoperative anterior cruciate ligament tunnel widening remains unknown. The present study reveals that significant tunnel widening occurs with quadrupled hamstring autografts and femoral cross pin fixation. However, the widening does not appear to have a significant effect on postoperative ligament laxity or functional knee scores, at least in the short term.

Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 5 (May-June), 2003: pp 470–476

Keywords:  ACL reconstruction, Tunnel enlargement, Femoral tunnel widening, Ham-string tendon, Cross pin