Magnetic resonance imaging evaluation of anterior cruciate ligament reconstruction using quadrupled hamstring tendon autografts: comparison of remnant bundle preservation and standard technique

Abstract

Background: Recently, variations of the remnant bundle preservation technique, including selective bundle reconstruction and preservation of the anterior cruciate ligament tibial remnant, have produced good outcomes. The authors chose to investigate whether remnant bundle preservation in anterior cruciate ligament reconstruction would affect the remodeling process without inducing complications.

Hypothesis: An anterior cruciate ligament reconstruction graft can be augmented with a tensioned remnant of the native anterior cruciate ligament fibers without increasing the tendency of cyclops lesions. The magnetic resonance imaging signal intensity in an anterior cruciate ligament graft using the remnant bundle preservation technique would be lower than that using the standard technique.

Study design: Cohort study; Level of evidence, 3.

Methods: Forty-one patients who underwent an anterior cruciate ligament reconstruction using the remnant bundle preservation technique with quadrupled hamstring tendon autograft were evaluated by magnetic resonance imaging at a mean of 6.3 +/- 0.7 months after surgery. The control group included 41 consecutive patients who underwent a single-bundle anterior cruciate ligament reconstruction by the standard technique. The 2 groups did not differ significantly in gender, age distribution, mean time until postoperative magnetic resonance imaging, or other patient characteristics. The magnetic resonance imaging evaluation focused on 5 measurements as follows: (1) dimensions of the anterior cruciate ligament graft, (2) signal intensity of the anterior cruciate ligament graft using the signal/noise quotient (SNQ) from a region of interest analysis, (3) magnetic resonance imaging signal intensity and continuity of the preserved remnant bundle, (4) orientation of the anterior cruciate ligament, and (5) tibial tunnel placement.

Results: The remnant bundle preservation group had a significantly larger mean anterior cruciate ligament graft (293.4 mm(2)) than did the standard group (219.6 mm(2)) (P < .0001). However, the SNQ values of the anterior cruciate ligament graft in the remnant bundle preservation group were not significantly lower than those in the standard group in any of the 3 zones. In the remnant bundle preservation group, magnetic resonance imaging signals obtained from preserved remnant bundles in 35 patients (85%) showed 14 knees with a grade I signal (homogeneous low intensity) and 21 knees with a grade II signal (a portion of the preserved bundle was edematous). The continuity of remnant bundles in 37 patients (90%) as determined by magnetic resonance imaging was partial in 20 patients and complete in 17. The 2 groups did not differ significantly in the number of cyclops lesions detected by postoperative magnetic resonance imaging.

Conclusion: After anterior cruciate ligament reconstruction, magnetic resonance imaging showed significantly larger anterior cruciate ligament grafts in the remnant bundle preservation group than in the standard procedure group, and these preserved remnant bundles showed progressive remodeling in the anterior cruciate ligament graft with no increase in the incidence of cyclops lesions. To determine a clinical advantage for the remnant preservation technique, magnetic resonance imaging results such as these must be correlated with clinical findings.