Background
No reliable tools are able to predict which patients will become “copers” following a trial of non-operative treatment after an ACL injury. Some authors suggest a strategy of rehabilitation with the option of delayed reconstruction, whereas others recommend early reconstruction. A delay in ACLR could increase intra-articular knee shear forces. Questions remain about the safe time interval from injury to ACLR in reducing the prevalence of concomitant intra-articular injuries and only a few studies have evaluated the effect of delayed ACLR on meniscus repair rates. Variables such as age, gender and BMI have also been suggested as factors potentially correlated with the development of intra-articular injuries and the likelihood of meniscus repair. Finally, the effect of these demographic characteristics and the potential benefits of early ACLR on knee laxity are poorly studied.
Purpose
To determine the association between a delay in ACLR, age, gender, BMI and cartilage injuries, meniscus injuries, meniscus repair, and abnormal pre-reconstruction laxity.
Methods
A total of 3,976 patients who underwent primary ACLR at our institution from 2005 to 2017, with no associated ligament injuries, were included. Logistic regression analyses were used to evaluate whether delay in ACLR, age, gender and BMI were risk factors for cartilage and meniscus injuries, meniscus repair, and abnormal (side-to-side difference >5mm) pre-reconstruction laxity.
Results
The risk of cartilage injury increased with a delay in ACLR (12-24 months: odds ratio[OR], 1.20; 95% confidence intervals[CI],1.05-1.29; P=.005; and >24 months: OR,1.20; 95% CI, 1.11-1.30; P<.001) and age =>30 years (OR, 2.27; 95% CI, 1.98-2.60; P<.001). The risk of medial meniscus (MM) injury increased with a delay in ACLR (12-24 months: OR, 1.20; 95% CI, 1.07-1.29; P=.001; and >24 months: OR,1.22; 95% CI, 1.13-1.30; P<.001), male gender (OR, 1.16; 95% CI, 1.04-1.30; P=.04) and age =>30 years (OR, 1.20; 95% CI, 1.04-1.33; P=.008). The risk of lateral meniscus (LM) injury decreased with a delay in ACLR of >3 months and age =>30 years (OR, 0.75; 95% CI, 0.66-0.85; P<.001), whereas it increased with male gender (OR,1.32; 95% CI,1.22-1.41; P <.001). MM repairs relative to MM injury decreased with a delay in ACLR (6-12 months: OR, 0.70; 95% CI, 0.54-0.92; P=.01; 12-24 months: OR, 0.69; 95% CI, 0.57-0.85; P<.001; >24 months: OR, 0.61; 95% CI, 0.52-0.72; P<.001) and age =>30 years (OR, 0.60; 95% CI, 0.48-0.74; P<.001). LM repairs relative to LM injury only decreased with age =>30 years (OR, 0.34; 95% CI, 0.26-0.45; P <.001). The risk of having abnormal knee laxity increased with a delay in ACLR of >6 months and MM injury (OR, 1.52; 95% CI, 1.16-1.97; P=.002), whereas it decreased with a BMI of =>25 kg/m2 (OR, 0.68; 95% CI, 0.52-0.89; P=.006).
Conclusions
A delay in ACLR of >12 months increased the risk of cartilage and MM injuries, while a delay of >6 months increased the risk of abnormal pre-reconstruction laxity and reduced the likelihood of MM repair. To reduce meniscus loss and the risk of jeopardizing knee laxity, ACLR should be performed within 6 months after the injury.