Paper 14: Generalized joint hypermobility leads to an 8-fold increase in the odds of sustaining a second ACL injury within 24 months of return to sport after ACL reconstruction
Authors: Zsidai Bálint , Piussi Ramana , Thomeé Roland , Sundemo David , Musahl Volker , Samuelsson Kristian , Senorski Eric Hamrin 
Published: March 2023

Objectives: To investigate the association between generalized joint hypermobility (GJH) and the 24-month incidence of a second ipsilateral or contralateral anterior cruciate ligament (ACL) injury in a population of patients who return to sport (RTS) after ACL reconstruction (ACL-R). Methods: Data for this study were queried from a Swedish rehabilitation specific registry called Project ACL. Ethical approval for this project was granted by the Regional Ethical Review Board in Sweden (registration numbers: 265-13, T023-17) and the Swedish Ethical Review Authority (registration number: 2020-02501). Patients with a primary ACL tear treated with ACL-R who were 16-50 years old and registered in Project ACL between 2014 – 2019 were considered eligible for inclusion. Return to sport was defined as a return to ³6 Tegner activity level. Patients with 5 positive tests on the Beighton scale were considered to fulfill criteria for GJH. Patients with missing GJH data, and patients with Tegner activity level <6 preoperatively or at the time of RTS were excluded from further analysis. The study population was divided into GJH and non-GJH groups based on the screening criteria. The extracted data for eligible patients consisted of demographics, surgical variables and patient reported outcome measures (Table 1). Incidence of a second (ipsilateral or contralateral) ACL injury during the follow-up period after ACL-R was registered as a dichotomous variable. Demographic, injury-related, surgical and follow-up data were reported using descriptive statistics including frequency (n) and proportion (%) for categorical variables and mean ± standard deviation (SD) or median with range for continuous variables. For comparison between groups Fisher’s Exact test was used for dichotomous variables, Chi Square Exact test was used for non-ordered categorical variables and the Fisher’s Non Parametric Permutation Test was used for continuous variables. Univariable logistic regression was performed to determine the influence of GJH and timing of RTS (Tegner activity level ³ 6) on the odds of a second ACL injury following ACL-R within 2 years of RTS. Results: A total of 153 patients were deemed eligible for this study. Primary ACL-R was performed in 34 (22%) patients with GJH and 119 (78%) non-GJH patients. Patients with GJH were younger at the time of ACL-R (21.8 vs 24.5 years; p = 0.049) and had a shorter time from surgery to RTS (8.1 vs. 10.3 months; p = 0.044). Within 24 months of RTS, 6 (17.6%) patients with GJH and 3 (2.5%) non-GJH patients had a second ACL injury ( p = 0.0082). Return to preinjury Tegner activity level was achieved by 29 (85.3%) GJH patients and 114 (74.5%) non-GJH patients ( p = 0.15; Table 1). There was no statistically significant difference in preoperative and postoperative Knee Injury and Osteoarthritis Outcome Score subscales and psychometric measures of risk appraisal at RTS between the GJH and non-GJH groups (Table 2). The odds of sustaining a second ACL injury was 8.29 in GJH compared to non-GJH patients (95% confidence interval = 1.95-35.18; p = 0.0042; area under the receiver operating characteristic curve = 0.74; Table 3). Conclusions: Patients with GJH undergoing ACL-R have an 8 times greater odds of sustaining a second ACL injury after RTS. Consequently, GJH should be considered a risk-factor for repeat ipsilateral or contralateral ACL injury, and the importance of joint laxity assessment should be emphasized in patients who aim to return to high-intensity sports following ACL-R. [Table: see text][Table: see text][Table: see text][Table: see text]