A Cross-sectional Examination of Quadriceps Strength, Biomechanical Function, and Functional Performance From 9 to 24 Months After Anterior Cruciate Ligament Reconstruction

Psychological Factors Are Related to Neuromuscular Asymmetries After Anterior Cruciate Ligament Reconstruction

BACKGROUND

After an anterior cruciate ligament reconstruction (ACLR), only 47% of military members return to full duty, possibly due to persistent neuromuscular asymmetries. Psychological factors may also contribute to reduced return to duty in military members.

HYPOTHESIS

Psychological factors and time since surgery would be associated negatively with neuromuscular asymmetries, asymmetries would be greater in cadets postsurgery when compared with healthy controls, and asymmetries would be greater at earlier timepoints after ACLR.

STUDY DESIGN

Case control.

LEVEL OF EVIDENCE

Level 4.

METHODS

This study examined the relationship between psychological factors and time since surgery with neuromuscular asymmetry, compared neuromuscular asymmetries between cadets with and without a history of ACLR, and explored differences in neuromuscular asymmetries at different timepoints in cadets with a history of ACLR. A total of 37 cadets post-ACLR (18.3 ± 9 months) and 28 controls participated. Psychological factors were assessed using the Tampa Scale of Kinesiophobia and Anterior Cruciate Ligament-Return to Sport after Injury scale (ACL-RSI). Participants performed a drop-jump landing, joint positioning sense (JPS), and isometric quadriceps strength testing. Peak vertical ground-reaction forces (vGRF), absolute angle of replication, peak quadriceps torque, rate of torque development (RTD), and RTD time torque interval 200 ms (TTI200) were analyzed.

RESULTS

The ACL-RSI score was significantly related to limb symmetry index (LSI) peak quadriceps torque (r = 0.617, P < 0.01), LSI RTD (r = 0.367, P = 0.05), and LSI TTI200 (r = 0.0489, P < 0.01), but not time since surgery, JPS, or LSI peak vGRF. Cadets with a history of ACLR had significantly lesser ACL-RSI scores and greater asymmetries compared with controls.

CONCLUSION

Reduced psychological readiness was associated with increased neuromuscular asymmetries after ACLR.

CLINICAL RELEVANCE

Clinicians should assess psychological readiness during rehabilitation after ACLR.

Kinetics During the Tuck Jump Assessment and Biomechanical Deficits in Female Athletes 12 Months After ACLR Surgery

BACKGROUND

Residual interlimb deficits after anterior cruciate ligament reconstruction (ACLR) can lead to functional maladaptation and increase the risk of reinjury. The tuck jump assessment (TJA) may offer a more effective evaluation of ACLR status as compared with traditional tasks owing to increased risk of altered landing mechanics, asymmetrical landing, and increased knee valgus attributed to the cyclical nature of the task. However, it remains unclear whether altered TJA kinetics resolve over time or persist through return-to-play phases of rehabilitation.

PURPOSE

To examine longitudinal kinetics, asymmetries, and functional performance deficits during TJA at 9 and 12 months after ACLR in female athletes at high risk of reinjury.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Female athletes (ACLR, n = 24; controls, n = 19; total, N = 43) performed a single trial of TJA on dual-force plates at 2 time points. The ACLR group (mean ± SD age, 16.8 ± 1.9 years) was tested at 9 and 12 months after surgery, and the control group (16.5 ± 3.6 years) was tested at similar time points. All athletes participated in similar sports and had comparable activity levels. Discrete time point analysis and statistical parametric mapping were used to identify deficits within each group.

RESULTS

At 9 months after surgery, the ACLR group exhibited significant interlimb differences in all kinetic variables (P < .05), which persisted at 12 months with only small reductions in magnitude. As compared with controls, the ACLR group demonstrated a persistent offloading strategy in the involved limb by exhibiting larger interlimb asymmetries for a range of kinetic variables and a greater vertical ground-reaction force in the uninvolved limb during most of the stance phase at both time points (P < .001). Distinct differences in functional performance of TJA were evident at both time points, characterized by lower peak vertical ground-reaction force, peak center of mass displacement, and relative vertical leg stiffness and longer ground contact times (P < .001).

CONCLUSION

This study revealed that young female athletes after ACLR exhibit persistent interlimb deficits and functional maladaptations up to 12 months after surgery. The TJA identified significant biomechanical impairments to both limbs, resulting in asymmetrical loading and altered movement strategies as compared with healthy controls. Despite some improvements, athletes with ACLR continued to demonstrate offloading to the uninvolved limb, indicating incomplete neuromuscular recovery.

Acute and Chronic Effects of Blood Flow Restriction Training in Physically Active Patients With Anterior Cruciate Ligament Reconstruction: A Systematic Review

CONTEXT

Muscle atrophy and loss of knee function are common findings after anterior cruciate ligament (ACL) reconstruction. Rehabilitation through blood flow restriction (BFR) has gained clinical relevance when combined with low loads to improve these disorders in recent years.

OBJECTIVE

To evaluate the rehabilitation effectiveness of ACL reconstruction with the use of BFR on pain, functionality, strength, and muscle mass in physically active people.

DATA SOURCES

A search of PubMed, Web of Science, and MEDLINE was performed on March 31, 2023, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines.

STUDY SELECTION

Randomized clinical trials with active adults who underwent ACL surgery were included. They had to compare conventional treatments with the use of BFR, reporting values of pain, functionality, strength, or cross-sectional area (CSA). Articles whose participants presented concomitant injuries and whose intervention combined the use of BFR with treatments other than resistance training were excluded.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 2.

DATA EXTRACTION

Study design, population, cuff pressure, and main outcomes including strength, quadriceps CSA, pain, and functionality.

RESULTS

Six studies out of a total of 389 were included (152 participants; 90 men and 62 women). These included studies showed no differences on CSA or strength when comparing BFR training with high loads exercise. BFR has demonstrated improvements in knee functionality and pain compared with other interventions such as immobilization or high loads training.

CONCLUSION

The use of low loads combined with BFR improves pain, strength, functionality, and CSA. In addition, knee pain reduction and functionality are greater with BFR compared with the use of high loads or immobilization.

Limb Symmetry Index of Single-Leg Vertical Jump vs. Single-Leg Hop for Distance After ACL Reconstruction: A Systematic Review and Meta-analysis

CONTEXT

The limb symmetry index (LSI) is recommended as a milestone of return to play (RTP), and relying on the LSI value of a single-leg hop for distance (SLHD) test may overestimate rehabilitation status. Identifying a more reliable functional test can help to carefully make decisions for RTP.

OBJECTIVE

The aim was to compare the LSI value of the SLHD test with that of a single-leg vertical jump (SLVJ) test after anterior cruciate ligament reconstruction (ACLR) and determine which test provides lower LSI values.

DATA SOURCES

The PubMed, Web of Science, Embase, and Cochrane Library databases were searched from inception to July 2022.

STUDY SELECTION

Observational studies with participants who had both SLHD and SLVJ tests after ACLR and LSI values of an SLHD and SLVJ were included. Disagreements were resolved after discussion between the 2 researchers.

STUDY DESIGN

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Data on the primary outcomes (LSI values of the SLVJ and SLHD tests) were collected. Means and standard deviations (SDs) for each variable of interest were used to calculate standardized mean differences (SMDs).

RESULTS

A total of 12 studies met the inclusion criteria for the meta-analysis. A total of 587 patients underwent SLHD and SLVJ tests at different time points after ACLR. Compared with the SLHD test, the SLVJ test provided lower LSI values (SMD -0.42; 95% confidence interval (CI) -0.67 to -0.17). Subgroup analysis found that the SLVJ test provided a lower LSI value than the SLHD test in a specific period (approximately 7-18 months after ACLR, SMD -0.53; 95% CI -0.91 to -0.14) and a similar LSI value at other times.

CONCLUSION

The SLVJ test provided lower LSI values in a specific period (7-18 months after ACLR).

Proprioceptive and clinical outcomes of anterior cruciate ligament reconstruction with remnant tissue preservation technique: A comparison according to the preserved tissue length

BACKGROUND

No consensus is obtained regarding the effects of remnant-preserving ACL reconstruction on long-term clinical and proprioceptive outcomes. This study aimed to compare proprioceptive and clinical outcomes of the knee joint after ACL reconstruction with two different lengths of preserved remnant tissue.

METHODS

This study included 61 patients who underwent single-bundle ACL reconstruction with remnant preservation method using hamstring autograft, divided into two groups according to the length of the remnant tissue. Group ≤33% included subjects with equal and less than 1/3 of the remnant preserved (n = 30) and group >33% included subjects with more than 1/3 of the remnant preserved (n = 31). Proprioception was evaluated at 20°, 50°, and 70° knee angles. Clinical outcome measures included Tegner activity scale, Lysholm knee score, single-leg-hop test, and muscle strength of quadriceps femoris and hamstring muscles which was evaluated using Biodex dynamometer. Anterior laxity was determined with a KT2000 arthrometer. A statistical comparison of the assessments was performed.

RESULTS

The mean follow-up time after surgery were 28.33 and 33.67 months for group ≤33% and >33%, respectively. No significant differences were detected for Lysholm and Tegner scores between the groups (p > 0.05). Additionally, proprioception and muscle strength values displayed similarity between the groups (p > 0.05). The length of the remnant tissue did not affect post-operative knee stability (p > 0.05).

CONCLUSION

Patients who underwent remnant-preserving ACL reconstruction obtained similar proprioceptive function, muscle strength, anterior stability, and clinical results regardless of the amount of preserved tissue length at short-term assessment.

Better Safe Than Sorry? A Systematic Review with Meta-analysis on Time to Return to Sport After ACL Reconstruction as a Risk Factor for Second ACL Injury

OBJECTIVE: To compare the time to return to sport (RTS) between patients who did and did not suffer a second anterior cruciate ligament (ACL) injury after ACL reconstruction. DESIGN: Etiology systematic review with meta-analysis. LITERATURE SEARCH: Cochrane Library, Embase, Medline, AMED, and PEDro databases were searched in August 2021 and again in November 2022. STUDY SELECTION CRITERIA: Clinical studies reporting time to RTS after ACL reconstruction and second ACL injury were eligible. DATA SYNTHESIS: We pooled continuous data (time [months] and proportions [%]), with random-effects meta-analyses. Pooled estimates were summarized in forest plots. A qualitative data synthesis was also performed. RESULTS: Twenty-one studies were included in the meta-analysis and 33 in the qualitative synthesis. Pooled incidence of second ACL injury was 16.9% (95% confidence interval [CI]: 12.8, 21.6). Patients who suffered a second ACL injury returned to sport significantly earlier (25 days; 95% CI: 9.5, 40.4) than those who did not suffer another injury. There was no difference in time to RTS for professional athletes who suffered a second ACL injury and those who did not. The certainty of evidence was very low. CONCLUSION: There was very low-certainty evidence that patients who suffered a second ACL injury had returned to sport 25 days earlier than patients who did not have another injury. For professional athletes, there was no difference in time to RTS between athletes who suffered a second ACL injury and athletes who did not. J Orthop Sports Phys Ther 2024;54(3):1-15. Epub 30 November 2023. doi:10.2519/jospt.2023.11977.

Combining age, sex, body mass index, sport level, and preoperative quadriceps strength improves the predictive ability of quadriceps strength recovery after anterior cruciate ligament reconstruction

PURPOSE

This study compared the predictive ability of each independent predictor with that of a combination of predictors for quadriceps strength recovery one year after anterior cruciate ligament (ACL) reconstruction.

METHODS

Patients who underwent primary ACL reconstruction using hamstring autografts were enrolled. Quadriceps strength, hamstring strength, and anterior tibial translation were measured, and the limb symmetry index (LSI) of the quadriceps and the hamstrings was calculated preoperatively and one year after surgery. Patients were classified into two groups according to the LSI of the quadriceps strength at one year postoperatively (≥ 80% or < 80%). Multivariate logistic regression analysis identified the independent predictors of quadriceps strength recovery, and the cut-off value was calculated using the receiver operating characteristic curve. A model assessing predictive ability of the combination of independent predictors was created, and the area under the curve (AUC) for each independent predictor was calculated by using the receiver-operating characteristic curves and the DeLong method.

RESULTS

Of the 646 patients, 414 (64.1%) had an LSI of at least 80% for quadriceps strength one year after surgery, and 232 patients (35.9%) had an LSI of < 80%. Age, sex, body mass index (BMI), preinjury sport level, and LSI of preoperative quadriceps strength were independently associated with quadriceps strength recovery one year after ACL reconstruction. The cut-off values were age: 22.5 years; sex: female; BMI: 24.3 kg/m2; preinjury sport level: no sport; and LSI of preoperative quadriceps strength: 63.3%. The AUC of the model assessing the predictive ability of the combination of age, sex, BMI, preinjury sport level, and LSI of preoperative quadriceps strength was significantly higher (0.73) than that of similar factors of preoperative quadriceps strength (AUC: 0.63, 0.53, 0.56, 0.61, and 0.68, p < 0.01, respectively).

CONCLUSION

The combination of age, sex, BMI, preinjury sport level, and LSI of preoperative quadriceps strength had a superior predictive ability for quadriceps strength recovery at one year after ACL reconstruction than these predictors alone. Multiple factors, including patient characteristics and preoperative quadriceps strength, should be considered when planning rehabilitation programs to improve quadriceps strength recovery after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Comparison of Dynamic Balance and Unilateral Hop Performance Between Women and Men Handball Players After Anterior Cruciate Ligament Reconstruction: A Pilot Study

CONTEXT

After anterior cruciate ligament reconstruction (ACLR), long-term functional deficiencies can occur, with controversial results reported when comparing women and men. Dynamic balance and unilateral hop test performance are considered important indicators for the risk of reinjury of the lower extremity. Although both sexes seem to have a similar risk to experience a second anterior cruciate ligament injury, sex-specific differences of dynamic balance and unilateral hop performance in handball players following ACLR are unknown.

OBJECTIVE

To compare dynamic balance and unilateral hop performance between women and men handball players at least 6 months after ACLR.

DESIGN

Cross-sectional pilot study.

PARTICIPANTS

Ten women (27.6 [4.5] y) and 10 men (26.5 [3.1] y) handball players 6 to 16 months after ACLR.

OUTCOME MEASURES

Dynamic balance and unilateral hop performance were assessed using the Y-Balance Test and the Single-Leg Hop for Distance Test.

RESULTS

Women players demonstrated significantly better results in the anterior direction of the Y-Balance Test for both legs compared with men players. Hop performance was not significantly different between sexes.

CONCLUSION

Dynamic balance and single-leg hop performance seem not to differ between women and men handball players 6 to 16 months after ACLR. The difference between sexes in the anterior reach direction of the Y-Balance Test should be considered small, rather than representing a true difference.

Return to Sport After Anterior Cruciate Ligament Reconstruction Requires Evaluation of >2 Functional Tests, Psychological Readiness, Quadriceps/Hamstring Strength, and Time After Surgery of 8 Months

PURPOSE

The purpose of this study was to examine the factors commonly used to determine readiness for return to sport (RTS) in the ACL reconstruction (ACL-R) patient population and assess which were most influential to successfully returning to sport and avoiding re-tear.

METHODS

The PUBMED, EMBASE and Cochrane Library databases were queried for studies related to RTS in ACL-R. Inclusion and exclusion criteria were applied to identify studies with greater than 1-year outcomes detailing the rate of return and re-tear given a described RTS protocol. Data of interest were extracted, and studies were stratified based on level of evidence and selected study features. Meta-analysis or subjective synthesis of appropriate studies was used to assess more than 25 potentially significant variables effecting RTS and re-tear.

RESULTS

After initial search of 1503 studies, 47 articles were selected for inclusion in the final data analysis, including a total of 1432 patients (31.4% female, 68.6% male). A meta-analysis of re-tear rate for included Level of Evidence 1 studies was calculated to be 2.8%. Subgroups including protocols containing a strict time until RTS, strength testing, and ≥2 dynamic tests demonstrated decreased RTS and re-tear heterogeneity from the larger group. Time to RTS, strength testing, dynamic functional testing, and knee stability were also found to be among the most prevalent reported criteria in RTS protocol studies.

CONCLUSIONS

This study suggests a multifactorial clinical algorithm for successful evaluation of RTS. The "critical criteria" recommended by the authors to be part of the postoperative RTS criteria include time since surgery of 8 months, use of >2 functional tests, psychological readiness testing, and quadriceps/hamstring strength testing in addition to the modifying patient factors of age and female gender.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Functional Resistance Training Improves Thigh Muscle Strength after ACL Reconstruction: A Randomized Clinical Trial

PURPOSE

Quadriceps weakness is common after anterior cruciate ligament (ACL) reconstruction, resulting in prolonged disability and increased risk for reinjury and osteoarthritis. Functional resistance training (FRT) combines resistance training with task-specific training and may prove beneficial in restoring quadriceps strength. The primary purpose of this study was to determine if a walking-specific FRT program (e.g., resisted walking) improves knee strength in individuals after ACL reconstruction.

METHODS

Thirty participants were randomized into one of three groups: 1) FRT with a customized knee BRACE applied to the ACL leg, 2) FRT with elastic BAND tethered to the ankle of the ACL leg, or 3) a TARGET MATCH condition where no resistance was externally applied. Participants in all groups received training while walking on a treadmill 2-3 times per week for 8 wk. Isometric knee extension and flexion strength were measured before the start of the intervention, after the intervention (POST), and 8 wk after intervention completion (POST-2).

RESULTS

The BRACE group had greater knee extensor strength compared with the TARGET MATCH group at POST and POST-2 ( P < 0.05). The BRACE group had greater knee flexor strength than the TARGET MATCH group at POST and POST-2 ( P < 0.05) and the BAND group at POST ( P < 0.05).

CONCLUSIONS

FRT applied via a customized knee brace results in improvements in knee extensor and flexor strength after ACL reconstruction. FRT is a beneficial adjuvant to ACL rehabilitation and leads to better strength compared with standard of care.

Reactive strength index during single-limb vertical continuous jumps after anterior cruciate ligament reconstruction: cross-sectional study

BACKGROUND

The association of the reactive strength index (RSI) during single-limb vertical continuous jumps (SVCJs) with single-limb hop tests in athletes after anterior cruciate ligament reconstruction (ACLR) is unclear. Thus, this study aimed to confirm the measurement properties of the RSI during SVCJs in athletes with ACLR at the phase of determining the timing of their return to sport.

METHODS

RSI during SVCJs and single-limb hop (single, triple, and crossover) tests were measured for post-ACLR and healthy athletes. The limb symmetry index (LSI) was calculated using the measurements of each parameter. For each test, patients were divided into two subgroups according to their LSI score (≥ 90%, satisfactory; < 90%, unsatisfactory). Fisher's exact test was used to examine the association of single-limb hop tests with RSI during the SVCJs.

RESULTS

A total of 21 post-ACLR and 17 healthy athletes completed all the tests. RSI during SVCJs was significantly lower on the involved limb than on the uninvolved limb in post-ACLR athletes (P < 0.001). The LSI of RSI during SVCJs of post-ACLR athletes was significantly lower than that of the healthy athletes (P < 0.01). Among the post-ACLR athletes, < 30% of those with LSIs > 90% in the single-limb hop tests had an LSI > 90% of the RSI during SVCJs.

CONCLUSIONS

RSI during SVCJs of post-ACLR athletes was significantly lower on the involved limb than on the uninvolved limb, and the asymmetry was more remarkable in the SVCJs than in the single-limb hop tests.

Landing biomechanics deficits in anterior cruciate ligament reconstruction patients can be assessed in a non-laboratory setting

Landing biomechanics provide important information pertaining to second anterior cruciate ligament (ACL) injury risk in patients following ACL reconstruction (ACLR). While traditional motion analysis technologies are often impractical for use in non-laboratory settings, methods to assess landing biomechanics which are inexpensive, portable, and user-friendly have recently been developed and validated. The purpose of this study was to compare landing kinematics and kinetics between ACLR patients and uninjured controls in a non-laboratory setting. Sixteen ACLR patients (7 male/9 female, 6-12 months post-ACLR) and 16 gender-matched controls completed seven bilateral drop vertical jumps and seven unilateral drop landings on each limb. Plantar force was measured bilaterally using force sensing insoles and frontal and sagittal-plane knee kinematics were measured using two tablets, six reflective markers, and automated point tracking software. Plantar force impulse normalized symmetry index (NSI) and knee frontal plane projection angle (FPPA) range of motion were computed during bilateral landing, and knee flexion range of motion NSI was computed during unilateral landing and compared between groups using independent samples t tests. ACLR patients had larger NSIs (reflecting less symmetry) for plantar force impulse during bilateral landing (p < 0.001) and knee flexion range of motion during unilateral landing (p = 0.004). No between-group differences were observed for knee FPPA range of motion (p = 0.111). This study is an important step towards assessing landing biomechanics in non-research settings with the goal of providing quantitative injury risk metrics in a clinical setting that can be used for return to sport decision making.

High Risk of New Knee Injuries in Female Soccer Players After Primary Anterior Cruciate Ligament Reconstruction at 5- to 10-Year Follow-up

BACKGROUND

A new anterior cruciate ligament (ACL) injury after ACL reconstruction is a feared outcome.

PURPOSE

To study the risk of new knee injuries in female soccer players 5 to 10 years after primary unilateral ACL reconstruction and to compare players who returned to soccer with (1) players who did not return and (2) knee-healthy soccer players (controls).

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Demographic, soccer-specific, and surgical data were recorded at baseline for 317 female soccer players (mean ± SD age, 20.1 ± 2.7 years) 1.6 ± 0.7 years after ACL reconstruction and for 119 matched controls (mean age, 19.5 ± 2.5 years). Data on new knee injuries and soccer-playing status were collected 5 to 10 years after ACL reconstruction via a questionnaire.

RESULTS

Among players with ACL reconstruction, 222 (70%) responded at a mean 6.5 ± 1.0 years after primary ACL reconstruction. We compared 3 cohorts: (1) among 163 players with ACL reconstruction who returned to soccer, 68 (42%) sustained 44 reruptures and 29 contralateral ruptures; (2) among 59 players with ACL reconstruction who did not return to soccer, 11 (19%) sustained 9 reruptures and 2 contralateral ruptures; and (3) among 113 knee-healthy controls, 12 (11%) sustained 13 ACL injuries. Players who returned had a >2-fold higher risk of a new ACL injury than players who did not return (risk ratio, 2.24; 95% CI, 1.27-3.93; P = .005) and a 4-fold higher risk than controls (risk ratio, 3.93; 95% CI, 2.23-6.91; P <.001). A new ACL, meniscal, or cartilage injury was the most frequent new knee injury. Among players who returned to soccer, 68% reported a new knee injury, and they had a 2- to 5-times higher risk of any new knee injury and knee surgery than players who did not return and controls.

CONCLUSION

Two-thirds of female soccer players with ACL reconstruction who returned to soccer sustained a new knee injury within 5 to 10 years; 42% had a new ACL injury. Their risk of a new knee injury and knee surgery was 2 to 5 times greater than that for players who did not return and for knee-healthy controls. New injury may have negative consequences for long-term knee health and should be a critical consideration in the decision to return to play.

Association Between Psychological Readiness and Knee Laxity and Their Predictive Value for Return to Sport in Patients With Anterior Cruciate Ligament Reconstruction

BACKGROUND

Deciding when patients are ready to return to sport (RTS) after an anterior cruciate ligament (ACL) reconstruction (ACLR) is challenging. The understanding of which factors affect readiness and how they may be related is limited. Therefore, despite widespread use of RTS testing, there is a lack of knowledge about which tests are informative on the ability to resume sports.

PURPOSE

To examine whether there is an association between knee laxity and psychological readiness to RTS after ACLR and to evaluate the predictive value of these measures on sports resumption.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients aged ≥16 years engaged in physical activity/sports before injury were recruited at routine clinical assessment 9-12 months after ACLR. Exclusion criteria were concomitant ligament surgery at ACLR and/or previous ACL injury in the contralateral knee. At baseline, a project-specific activity questionnaire and the ACL-Return to Sport After Injury (ACL-RSI) scale were completed. Knee laxity was assessed by use of the Lachman test, KT-1000 arthrometer, and pivot-shift test. Two years after surgery, knee reinjuries and RTS status (the project-specific questionnaire) were registered. Associations between psychological readiness and knee laxity were evaluated with the Spearman rho test, and predictive ability of the ACL-RSI and knee laxity tests were examined using regression analyses.

RESULTS

Of 171 patients screened for eligibility, 132 were included in the study. There were small but significant associations between the ACL-RSI score and the Lachman test (rho = -0.18; P = .046) and KT-1000 arthrometer measurement (rho = -0.18; P = .040) but no association between the ACL-RSI and the pivot-shift test at the time of recruitment. Of the total patients, 36% returned to preinjury sport level by 2 years after surgery. Higher age, better psychological readiness, and less anterior tibial displacement (KT-1000 arthrometer measurement) were significant predictors of 2-year RTS (explained variance, 33%).

CONCLUSION

Small but significant associations were found between measurements of psychological readiness and anterior tibial displacement, indicating that patients with less knee laxity after ACLR feel more ready to RTS. ACL-RSI and KT-1000 arthrometer measurements were independent predictors of 2-year RTS and should be considered in RTS assessments after ACLR.