Early surgery and number of injured ligaments are associated with postoperative stiffness following multi-ligament knee injury surgery: a systematic review and meta-analysis.

PURPOSE

To perform a systematic review and meta-analysis to investigate the rate of stiffness after multi-ligament knee injury (MLKI) surgery and identify potential risk factors associated with postoperative stiffness.

METHODS

This study was conducted in accordance with the 2020 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Registration was done on the PROSPERO International Prospective Register of Systematic Reviews (CRD42022321849). A literature search of PubMed, Ovid, Embase, and Cochrane Library databases was conducted in October 2022 for clinical studies reporting postoperative stiffness after MLKI surgery. A quality assessment was performed using the Methodological Index of Non-Randomized Studies (MINORS) grading system. The following variables were extracted from studies for correlation to postoperative stiffness: study characteristics, cohort demographics, Schenk classification, neurovascular injury, mechanism of injury, external fixator placement, timing of surgery, and concomitant knee injuries.

RESULTS

Thirty-six studies comprising 4,159 patients who underwent MLKI surgery met the inclusion criteria, including two Level-II, fourteen Level-III, and twenty Level-IV studies. The average MINOR score of the studies was 14. The stiffness rate after MLKI was found to be 9.8% (95% CI 0.07-0.13; p < 0.01; I = 87%), and the risk of postoperative stiffness was significantly lower for patients with two ligaments injured compared to patients with ≥ 3 ligaments injured (OR = 0.45, 95% CI (0.26-0.79), p = 0.005; I = 0%). The results of the pooled analysis showed early surgery (< 3 weeks) resulted in significantly increased odds of postoperative stiffness compared with delayed surgery (≥ 3 weeks) (OR = 2.18; 95% CI 1.11-4.25; p = 0.02; I = 0%). However, age, gender, body mass index, energy of injury, and neurovascular injury were not associated with an increased risk of postoperative stiffness (n.s.).

CONCLUSION

Performing surgery within the first 3 weeks following MLKI, or concomitant injury of ≥ 3 ligaments, are significantly associated with increased risk of postoperative stiffness. These findings can be utilized by surgeons to decide the timing of surgery for MLKI surgeries especially in which ≥ 3 ligaments are injured.

LEVEL OF EVIDENCE

Level IV.