Summary

Anatomic double-bundle ACL reconstruction with remnant tissue preservation was significantly improved postoperative knee stability and the 2nd-look arthroscopic evaluation compared to the remnant-resecting procedure in large number of patients.

Abstract

Objective

Recently, preservation of the ligament remnant tissue has attracted notice in the field of knee ligament reconstruction. Remnant preservation has been expected to have several potential advantages to improve postoperative knee stability, such as enhanced graft coverage, accelerated cell repopulation and revascularization (AJSM 2016). Previous studies compared clinical results between the remnant-preserving and remnant-resecting procedures after ACL reconstruction (AJSM 2015). In these studies, however, the number of patients was insufficient to compare the clinical results between the 2 procedures (Arthroscopy 2004). Recently, we have developed a new remnant-preserving technique for anatomic double-bundle ACL reconstruction (Arthroscopy 2012). The study hypotheses were as follows: (1) postoperative knee stability and the 2nd-look arthroscopic evaluation may be significantly more favorable with the remnant-preserving reconstruction. (2) Subjective and functional clinical results may be comparable between anatomic double-bundle ACL reconstructions that preserve the remnant tissue and those that resect the remnant tissue.

Methods

A total of 272 patients who underwent anatomic double-bundle ACL reconstruction with hamstring tendon autografts in the unilateral knee were unrolled in this study between 2009 and 2016. There were 162 men and 110 women with a mean age of 28 (13-71) years at the time of surgery. Based on the Crain classification of ACL remnant tissue, 133 knees having Crain Type I, II, or III remnant tissue underwent the remnant-preserving procedure (Group P). The remaining 139 knees having Crain Type IV underwent the remnant-resecting procedure (Group R). 243 (87.4%) of 272 knees underwent 2nd-look arthroscopy concerning graft thickness, apparent tension, and the synovium coverage of the graft according to our previous reported evaluation method (Arthroscopy 2007). The patients were followed for 2 years or more. This study design was accepted by the institutional review board in our hospital. Statistical analyses were made using Mann-Whitney U test and chi-square test. The significance level was set at p=0.05.

Results

There were no significant differences between the 2 groups concerning all background factors, including preoperative knee instability and tunnel positions. No serious complications were experienced in either group. Side-to-side anterior laxity measured at 30° was significantly less (p=0.004) in Group P (0.9 mm) than in Group R (1.4 mm). The pivot-shift test was negative in 90.6% of Group P and 74.7% of Group R; Group R was significantly lower (p=0.004). The Lysholm score averaged 96.9 and 96.0 points in Groups P and R, respectively. The International Knee Documentation Committee evaluation showed that 94, 22, and 3 knees were graded as A, B, and C, respectively, in Group P, while 80, 22, and 5 knees were graded A, B, and C, respectively, in Group R. The subjective and functional clinical results were comparable between the 2 reconstruction procedures. There were no significant differences in the other clinical evaluations between the 2 procedures. In the arthroscopic evaluations, the overall score in Group P were significantly better (p=0.017) than in Group R.

Conclusions

Anatomic double-bundle ACL reconstruction with remnant tissue preservation was significantly improved postoperative knee stability and the 2nd-look arthroscopic evaluation. However, it did not significantly improve subjective and functional results in the short-time evaluation.