Summary

This study suggested that earlier double-bundle anterior cruciate ligament (ACL) reconstruction may be beneficial for patients to stabilize and prevent secondary damages of the ACL injured knee, because of less postoperative knee instability and lower incidence of meniscal and chondral injuries.

Abstract

Introduction

Currently, several studies have recommended that single-bundle (SB) ACL reconstruction (R) should be performed in early phase after the injury to prevent associated meniscal or chondral lesions (KSSTA 2017). Recently, anatomic double-bundle (DB) ACL reconstruction procedures have attracted attention. Many randomized clinical trials have shown that these procedures are significantly superior to conventional SB procedures for knee stability, although other studies have failed to show significant differences (Arthroscopy 2015). However, its impact of surgical timing on clinical outcomes after DB ACL-R remains unclear. The purpose of this study was to clarify clinical outcomes after anatomic DB ACL-R among the different surgical timing.

Methods

A retrospective comparative study was conducted between 2004 and 2015 using patients who had an isolated unilateral ACL injury. The study design was accepted by the institutional review board in our hospital before commencement. A total of 179 patients who underwent DB ACL-R with hamstring tendon autografts were enrolled in this study. This surgery was performed with the original procedure (Arthroscopy 2004). These patients were divided into the four groups based on the injury-to-operation interval as follows; (1) within 1 month from injury (Group I); (2) between 1 and 3 months from injury (Group II); (3) between 3 and 6 months from injury (Group III); and (4) between 6 and 24 months from injury (Group IV). All the patients were evaluated at 2 years after surgery. Statistical analyses were made using the Tukey-Kramer test, chi-square test, Cochran-Armitage trend test and Spearman’s correlation. Significant level was set at p=0.05.

Results

There were no significant differences in background factors between the 4 groups, including pre-operative knee instability. The pre-operative isokinetic peak torques measured at 60°/sec of quadriceps and hamstrings muscle of Group II were significantly weaker than those of Group IV (p<0.0364). Significant correlations were found between the time to surgery and quadriceps and hamstrings muscle strengths (quadriceps; p=0.0029, hamstrings; p=0.0003). Post-operatively, no patients showed a loss of knee extension more than 5° and a loss of flexion more than 15°. Concerning the side-to-side difference in anterior knee laxity, there were no statistical differences among the all groups. In the pivot-shift test, shorter time to surgery were significantly associated with higher negative pivot shift incidence (p=0.034). Concerning the associated injuries, significantly higher rate of medial meniscal injury (p=0.0075) was seen in cases of delayed surgery compared to early cases. Moreover, the number of meniscal resections was significantly higher in cases of delayed surgery than in early surgery (p=0.0241). Regarding the medial compartment chondral injuries, longer time to surgery was associated with higher incidence of medial compartment chondral injury (p=0.0157). There were no significant differences in the other post-operative clinical evaluations among the all groups including the muscle strengths.

Conclusion

The pre-operative muscle strengths of quadriceps and hamstrings were significantly weaker in cases of early surgery than those of delayed surgery. Post-operative pivot shift test of the patients who underwent early surgery was significantly better than that of delayed surgery. Significantly higher rate of medial meniscal injury and medial compartment chondral injury was seen in cases of delayed surgery compared to early cases. Because medial meniscus is a secondary restraint to anterior drawer of the knee, delayed surgery led to higher rate of medial meniscal and chondral lesions. These results suggested that earlier DB ACL-R may be beneficial for patients to stabilize and prevent secondary damages of the ACL injured knee without a loss of range of motion.