Objective To investigate the association between sustaining a second anterior cruciate ligament (ACL) injury and (1) time to return to sport, (2) symmetrical muscle function, and (3) symmetrical quadriceps strength at the time of return to sport in young athletes after primary ACL reconstruction. Design Prospective cohort study. Methods Patient demographics and results from 5 tests of muscle function (2 strength tests and 3 hop tests) were extracted from a rehabilitation registry. A questionnaire was sent to athletes (15–30 years old) who were involved in knee-strenuous sport before the injury and had undergone primary ACL reconstruction to determine time of return to knee-strenuous sport (preinjury Tegner Activity Scale score of 6 or greater). We used the Cox proportional hazard regression model to analyze time to event. Results One hundred fifty-nine (32% of the initial sample) athletes (mean ± SD age, 21.5 ± 4.4 years; 50% female) were included. Athletes with a higher preinjury Tegner Activity Scale score had a higher rate of second ACL injury (hazard ratio = 2.1; 95% confidence interval: 1.2, 3.6; P<.01). Athletes who returned to knee-strenuous sport before 9 months after reconstruction had a higher rate of second ACL injury (hazard ratio = 6.7; 95% confidence interval: 2.6, 16.7; P<.001). There was no association between symmetrical muscle function or quadriceps strength and second ACL injury. Conclusion Returning to knee-strenuous sport before 9 months after ACL reconstruction was associated with an approximately 7-fold increased rate of sustaining a second ACL injury. Achieving symmetrical muscle function or quadriceps strength was not associated with new ACL injury in young athletes. J Orthop Sports Phys Ther 2020;50(2):83–90. doi:10.2519/jospt.2020.9071

PurposeThe purpose of this study was to evaluate the return to knee-strenuous sport rate, muscle function and subjective knee function among adolescent patients (15–20 years of age) and adult patients (21–30 years of age) 8 and 12 months, respectively, after anterior cruciate ligament (ACL) reconstruction. It was hypothesised that no differences in outcome would be found between age groups at 8 or 12 months after ACL reconstruction.MethodsCross-sectional data from five tests of muscle function, from the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Tegner Activity Scale (Tegner), performed at 8 and 12 months after a primary ACL reconstruction, were extracted from a rehabilitation outcome register. A total of 270 (51% women) athletes, aged 15–30 years, who were all involved in knee-strenuous sport prior the injury, were included at 8 months after ACL reconstruction. At 12 months 203 (51% women) were included. The return to knee-strenuous-sport rates and the rate of achieving a limb symmetry index of ≥ 90% in all five tests of muscle function, defined as recovery of muscle function, and subjective knee function scores, as measured with the KOOS, were compared between age groups.ResultsThe adolescent patients had a higher (50%) return to knee-strenuous sport rate compared with the adult patients (38%) 8 months after ACL reconstruction (p = 0.04). At the 12-month follow-up, no difference was found between the age groups; 74 and 63%, respectively. At the 8-month follow-up, 29% of the patients, in both age groups, who had returned to sport had recovered their muscle function in all five tests of muscle function. At the 12-month follow-up, the corresponding results were 20% for the adolescents and 28% for the adult patients. No difference in mean KOOS scores was found between the age groups at 8 or at 12 months after ACL reconstruction.ConclusionThe majority of young athletes make an early return to knee-strenuous sport after a primary ACL reconstruction, without recovering their muscle function. To set realistic expectations, clinicians are recommended to ensure that young athletes receive information about not to return before muscle function is recovered and that this may take longer time than 12 months.Level of evidenceII.

PurposeTo characterise patients who returned to knee-strenuous sports after an anterior cruciate ligament (ACL) reconstruction.MethodsData from isotonic tests of muscle function and patient-reported outcome measures, Tegner activity scale (Tegner and Lysholm in Clin Orthop Relat Res 198:43–49, 1985), physical activity scale, knee injury and osteoarthritis scale and knee self-efficacy scale were extracted from a registry. The 157 included patients, 15–30 years of age, had undergone primary ACL reconstruction and were all involved in knee-strenuous sports, i.e. pre-injury Tegner of 6 or higher. Return to sport was studied in two different ways: return to pre-injury Tegner and return to knee-strenuous sport (Tegner 6).ResultsFifty-two patients (33 %), who returned to pre-injury Tegner, 10 months after surgery, were characterised by better subjective knee function measured with the knee injury and osteoarthritis outcome score (p < 0.05), compared with patients who did not. These patients also had higher perceived self-efficacy of knee function (p < 0.01), measured with knee self-efficacy scale. Eighty-four patients (54 %) who returned to knee-strenuous sports, i.e. Tegner 6 or higher, were characterised by higher goals for physical activity (p < 0.01) and higher self-efficacy of future knee function (p < 0.05). Strength measurements showed that women who returned to sports were stronger in leg extension than women who did not. No differences were found in Limb Symmetry Index for knee strength or jumping ability.ConclusionPatients who returned to sports after ACL reconstruction had better subjective knee function and higher self-efficacy of knee function. Results highlight that further emphasis should be placed at psychological factors during rehabilitation of patients after ACLR.Level of evidenceII.

Background: Adult patients who succeed in returning to their preinjury levels of sport after anterior cruciate ligament (ACL) reconstruction have been characterized by a more positive psychological response. It is not known whether this relationship is valid for adolescent athletes. Purpose: To investigate psychological readiness to return to sport, knee-related self-efficacy, and motivation among adolescent (15-20 years old) and adult (21-30 years old) athletes after ACL reconstruction. A further aim was to compare athletes (15-30 years old) who had recovered their muscle function and returned to sport with athletes who had not. Study Design: Case-control study; Level of evidence, 3. Methods: Data were extracted from a rehabilitation-specific register 8 and 12 months after ACL reconstruction. Athletes previously involved in knee-strenuous sport who had undergone primary ACL reconstruction were included. Data comprised psychological patient-reported outcomes and results from 5 tests of muscle function. Comparisons were performed between age groups, between athletes who had and had not recovered their muscle function, and between patients who had returned to sport and not. Results: In all, 384 (50% females) and 271 athletes (52% females) were included at the 8- and 12- month follow-ups, respectively. Enhanced self-efficacy was reported at both follow-ups by adolescents and by athletes who had recovered their muscle function. Athletes who had recovered their muscle function reported higher ( P = .0007) motivation to achieve their goals. Subgroup analyses on patient sex revealed findings similar to those in the main analyses for females but not for males. Moreover, adolescent and adult athletes who had returned to sport reported significantly higher levels on the Knee Self-Efficacy Scale and the ACL–Return to Sport After Injury scale at both follow-ups. Conclusion: Adolescent athletes, especially females, perceived enhanced self-efficacy, had a higher return-to-sport rate, and were more motivated to reach their goals after ACL reconstruction compared with adults. Regardless of age, athletes who had returned to sport and athletes with more symmetrical muscle function had a stronger psychological profile.

Background:There is insufficient knowledge regarding the influence of concomitant injuries on the recovery of short-term subjective knee function after anterior cruciate ligament (ACL) reconstruction.Purpose:To determine whether patient characteristics, concomitant injuries, and graft choice during ACL reconstruction can predict which patients achieve acceptable knee function 1 year after reconstruction.Study Design:Case-control study; Level of evidence, 3.Methods:Data from 1 physical therapist–specific and 1 surgeon-specific register were used. Patients who had completed the Knee injury and Osteoarthritis Outcome Score (KOOS) at 1-year follow-up were included. Additional intraoperative information was extracted from a database. The primary outcome was achieving a patient-acceptable symptom state (PASS) for each subscale of the KOOS. Univariable and multivariable logistic regression models were used, with patient sex, age, and preinjury level of physical activity as covariates.Results:A total of 343 patients (51% females) were included. The proportion of patients achieving PASS 1 year after ACL reconstruction varied between 40% and 85% among the KOOS subscales. Younger age at reconstruction and male sex provided favorable odds of achieving acceptable knee function across the KOOS subscales. Patients without cartilage injury had increased odds of achieving PASS in the KOOS sport and recreation subscale; the increase was 1.63-fold (95% CI, 1.01-2.64; P = .045). Patients receiving patellar tendon autograft had a 0.41-fold (95% CI, 0.19-0.85; P = .017) decrease in odds of achieving PASS on the KOOS quality of life (QoL) subscale. In the multivariable analysis, increased odds of achieving PASS on the KOOS QoL subscale were associated with the absence of meniscal injury (odds ratio, 1.62; 95% CI, 1.04-2.54; P = .035), and increased odds were found for hamstring tendon autograft (OR, 2.63; 95% CI, 1.25-5.56; P = .011).Conclusion:More than half of the patients reported an acceptable symptom state on 4 of the 5 KOOS subscales 1 year after ACL reconstruction. A lack of consistency was noted related to the effect of concomitant knee injuries and graft choice on acceptable knee function. However, younger age and male sex were favorable, nonmodifiable characteristics that increased the odds of early acceptable function.