Summary

Despite advances with modern treatment, the current available evidence does not support improvements in the rate of recurrent knee instability after ACL repair as compared to historic treatment.

Abstract

Background

Primary ACL repair was historically performed and subsequently abandoned (in favor of ACL reconstruction) due to unacceptably high rates of failure at mid- and long-term follow-up. Recent advances in surgical technique and patient selection have resulted in a resurgence of interest in ACL repair. The purpose of this study is to compare historic and modern treatment outcomes of ACL repair.

Methods

Systematic review of Embase, Medline, and Pubmed databases were performed utilizing PRISMA guidelines. Study quality was assessed using the Modified Coleman Methodology Scoring (MCMS). Variables were collected pertaining to patient demographics, ACL tear location, concomitant meniscus and chondral injuries, timing to surgery, open versus arthroscopic procedure, ACL repair technique, timing of postoperative weight bearing and range of motion, recurrent knee instability, and revision ACL surgery. Descriptive statistics and proportional meta-analysis were performed using Freeman- Tukey transformation to calculate the weighted summary of ACL repair outcomes. Heterogeneity was assessed with I2 statistic. Primary outcome of interest was rate of recurrent knee instability.

Results

A total of 59 studies were included; comprised of 31 retrospective, 20 prospective, and 8 randomized control trials. The average MCMS was 69.2 (range: 30-95). A total of 3,365 patients were included (62.2% male, 37.8% female). The weighted rate of recurrent knee instability for historic techniques at short-, mid-, and long-term follow-up were 5.5%, 22.3%, and 23.1%, respectively. The weighted rate of recurrent knee instability for modern techniques at short- and mid-term follow-up were 11.3% and 26.7%; insufficient studies were available to assess long-term follow-up of modern techniques. The rate of recurrent instability for patients age <25 was 16.4% versus 14.4% age >25. The rates of recurrent knee instability based on type of ACL repair technique were suture anchor repair with synthetic augmentation 6.7%, suture repair with biologic augmentation 8.1%, bridge-enhanced ACL repair 9.4%, suture anchor repair 12.7%, dynamic intraligamentary stabilization 14.4%, suture repair with synthetic augment 21.5%, and suture repair alone 23.9%.

Conclusion

The literature assessing the clinical outcomes of primary ACL repair is heterogeneous and limited. Despite advances with modern treatment, the current available evidence does not support improvements in the rate of recurrent knee instability after ACL repair as compared to historic treatment.