Summary

This case series of isolated over-the-top ACL reconstruction demonstrated that post-operative anterior and rotatory knee laxity was restored in skeletally immature and revision settings.

Abstract

Introduction

Anterior cruciate ligament reconstruction (ACLR) with the over-the-top (OTT) technique, in which the graft is passed over the superomedial border of the lateral femoral condyle and fixed on the distal lateral femoral shaft, was originally used for primary ACLR. However, little is known about clinical outcomes following OTT ACLR for skeletally immature individuals and in revision cases. The purpose of the present study was to investigate the objective outcomes following OTT ACLR. The hypotheses were (1) anterior and rotatory knee laxity would be reduced after the surgery, and (2) graft failure rate would be equivalent compared to rates in the literature.

Methods

Thirty-five ACL-deficient patients who underwent isolated OTT ACLR with follow-up of 2.2 ± 1.4 years (range: 1.0-5.9) were retrospectively reviewed. This included 14 skeletally immature individuals (age at surgery: 14 ± 1 years; 8 male, 6 female) who underwent primary OTT ACLR (adolescent group) and 21 skeletally mature individuals (age: 25 ± 8 years; 10 male, 11 female) who underwent OTT revision ACLR (revision group). The tibial tunnel was created at the anatomic position for all cases. Graft diameter was 8.9 ± 0.6 mm in the adolescent group, and 9.6 ± 0.8mm in the revision group. No lateral extra-articular tenodesis was performed. Before and after surgery, the side-to-side difference (SSD, mm) in anterior laxity was measured using KT-1000 arthrometer. Lachman and pivot-shift tests were assessed according to IKDC grade. The graft failure rate (%) was assessed. Wilcoxon signed-ranks test was used to determine differences in knee laxity measurements prior to and after surgery.

Results

The post-operative SSD in anterior laxity was significantly reduced in the adolescent (pre-op, 3.9 ± 1.8 mm; post-op, 1.2 ± 0.8 mm; p = 0.040) and revision groups (pre-op, 4.2 ± 1.7 mm; post-op, 1.2 ± 1.4 mm; p < 0.001). Postoperative knee laxity measured by Lachman and pivot shift tests were also significantly improved in both groups. Graft re-tear occurred in 2 patients in the adolescent group (14.3 %), and one patient in the revision group (4.8%).

Discussion

Postoperative anterior and rotatory knee laxity was significantly reduced compared to the preoperative status following OTT ACLR. The graft failure rate appeared to be equivalent to rates previously reported in the literature. The OTT technique can be performed without risk of physeal injury in skeletally immature individuals. This technique may also be used in the revision setting with concerns of femoral tunnel compromise.

Conclusion

ACLR with the OTT technique appeared to restore anterior and rotatory knee laxity in skeletally immature individuals and in revision settings. These findings suggest that this procedure may be a good option for those cases.