Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study

Rehabilitation practices of Turkish physiotherapists following anterior cruciate ligament reconstruction: an online survey

We aimed to investigate the anterior cruciate ligament reconstruction (ACL-R) rehabilitation and return-to-sport (RTS) practices of Turkish physiotherapists. An online survey with 25 questions on ACL-R rehabilitation and RTS practices was created on Google Forms and distributed to physiotherapists via social media. Two-hundred sixty-four physiotherapists' responses were analysed. About 62.3% of therapists treated patients prior to ACL-R. Open-kinetic-chain (OKC) exercises frequently started at 4-6 weeks post-operatively (34.8%). Return-to-running cleared at 3-4 months (37%) and RTS cleared at 6-9 months (40.2%) mostly. Manual muscle tests were used by 58.4% of physiotherapists to evaluate knee strength before RTS. About 46.7% of physiotherapists did not assess psychological readiness for RTS. Physiotherapists with a bachelor's degree cleared patients for RTS earlier (<9 months) than those with postgraduate degrees (p = 0.001) but used patient-reported outcome measures (PROMs) more frequently (p = 0.010). Physiotherapists with over 5 years of experience used PROMs and psychological readiness scales more frequently (p = 0.035, p = 0.001) but also cleared patients for RTS earlier (p = 0.014). This study revealed that physiotherapist rehabilitation practices after ACL-R are not fully consistent with the current best evidence. This inconsistency in rehabilitation practices may lead to suboptimal patient outcomes after ACL-R. Encouraging physiotherapists to incorporate the latest evidence into practice might lead to better rehabilitation outcomes.

Anterior Cruciate Ligament Tears among Football Players

PURPOSE OF REVIEW

Anterior Cruciate Ligament (ACL) tears are one of the most common causes of lost playing time in American football athletes. Recently, there has been a push to get athletes back to sport faster. As such, numerous studies have evaluated management and rehabilitation protocols for return to play after ACL injury in football players. The purpose of this review is to synthesize information, both classic and new, to aid orthopedic surgeons in treatment of football players with ACL injuries.

RECENT FINDINGS

Recent studies have demonstrated that not all ACL injuries are alike. Management should be a shared decision-making process between athlete and surgeon. Studies have demonstrated low failure rates when using bone-patellar tendon-bone (BTPB) autograft which is the most common graft utilized for elite football athletes. Outcomes are continually being evaluated by multicenter study groups such as the Multicenter Orthopaedic Outcome Network which has established a thorough rehabilitation protocol focusing on athlete milestones. ACL tears in the football athlete are common and challenging injuries. Treatment revolves around ACL reconstruction, most commonly with BTPB autograft. Post-operative rehabilitation is essential and should focus on objective criteria rather than time elapsed. Return to play criteria rely upon symptoms, athlete confidence, strength, and both functional and football specific testing. Return-to-play timelines are individualized for each football athlete but recent trends have highlighted a more delayed return of at least 7-9 months. Rate of returning to play varies from 63-82% and depends upon many factors including level of play and position.

Validity of the Uninjured Limb as a Control for Preoperative Assessment in Anterior Cruciate Ligament Reconstruction

Monitoring muscle atrophy in patients undergoing anterolateral cruciate ligament reconstruction is pivotal for optimizing postoperative recovery. Conventionally, the uninjured contralateral limb serves as the control. However, its relevance in patients with prolonged physical activity hiatus due to knee instability remains uncertain. Our objectives were to compare limbs within a control group by assessing combined force measurements, cross-sectional areas (CSAs), and neuromuscular activation. In addition, we compared the contralateral limb of the surgery group preoperatively to the control group. This prospective controlled study (evidence level 2) included 40 healthy subjects (HG) and 30 patients scheduled for ACL surgery (SG). Both groups underwent identical assessments. The two HG limbs were compared to establish the standard difference for all assessed variables, whereas SG contralateral limb was compared with the mean of the control limbs. For HG, the comparisons between limbs showed no significant differences in muscle strength, CSA area, or electromyographic parameters. Similarly, comparisons between the SG contralateral limb and the mean of HG limbs revealed no significant differences in isometric and dynamic strength for the quadriceps and hamstrings (2.5 ± 0.5 and 2.6 ± 0.9 N.m/kg, and 1.7 ± 0.3 and 1.7 ± 0.4 N.m/kg, respectively). Neuromuscular activation and fatigue patterns were also comparable between groups. CSAs discrepancies were attributed to differences in body mass index between groups. These findings indicate that the contralateral limb in ACL_injured patients is functionally similar to that of healthy controls, supporting its use as a valid reference for monitoring postoperative recovery. Trial Registration: NCT03200678.

The P2X7R/NLRP3 inflammasome axis suppresses enthesis regeneration through inflammatory and metabolic macrophage-stem cell cross-talk

The regeneration of the enthesis remains a formidable challenge in regenerative medicine. However, key regulators underlying unsatisfactory regeneration remain poorly understood. This study reveals that the purinergic receptor P2X7 (P2X7R)/Nod-like receptor family protein 3 (NLRP3) inflammasome axis suppresses enthesis regeneration by amplifying IL-1β-mediated inflammatory cross-talk and suppressing docosatrienoic acid (DTA) metabolic cross-talk. NLRP3 inflammasomes were activated in macrophages following enthesis injury, thereby impairing the histological and functional recovery of the injured enthesis. Single-cell RNA sequencing (scRNA-seq) indicated that Nlrp3 knockout attenuated pathological inflammation and ameliorated the detrimental effects of IL-1β signaling cross-talk. Furthermore, NLRP3 inflammasomes suppressed the secretion of anti-inflammatory cytokines (IL-10 and IL-13) and DTA. The NLRP3 inflammasome-mediated secretome reduced differentiation and migration of stem cells. Neutralizing IL-1β or replenishing docosatrienoic acid accelerated enthesis regeneration. Moreover, conditional knockout of P2rx7 in myeloid cells attenuated NLRP3 inflammasome activation and facilitated enthesis regeneration. This study demonstrates that the P2X7R/NLRP3 inflammasome axis represents a promising therapeutic target for enthesis repair.

Is 9 months the sweet spot for male athletes to return to sport after anterior cruciate ligament reconstruction?

OBJECTIVE

Most studies examining the time to return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR) do not account for the athlete's physical readiness. This study aimed to investigate the status of male athletes at 2 years after ACLR, the factors affecting a return to pivoting sports, and the association between time to RTS and subsequent knee injury risk for those athletes who met discharge criteria.

METHODS

We prospectively followed 530 male athletes (mean age 26.7±7.7 years) participating in pivoting sports throughout rehabilitation and at 2 years after ACLR. Pair-wise analyses were conducted to compare athletes who returned to pivoting sports and those who did not. We performed a Cox regression analysis to assess the association between subsequent non-contact or indirect contact knee injuries and time to RTS. Pearson's χ2 test was used to compare athletes who RTS in ≤9 months to those who RTS in >9 months after ACLR.

RESULTS

In total, 379 (72%) athletes returned to pivoting sports at 2 years after ACLR. Athletes who completed rehabilitation and met discharge criteria (n=190) were almost 6 times more likely to return to their preinjury sport (OR 5.71; 95% CI 3.39 to 9.62). Of those who did not complete their rehabilitation (n=340), 132 (39%) did not return to pivoting sports. For athletes who met discharge criteria, time to RTS was not associated with the risk of new knee or ACL injury. There was no increased risk for new knee (HR 0.892, 95% CI 0.39 to 2.07, p=0.79) or ACL (HR 0.718, 95% CI 0.24 to 2.17, p=0.56) injury whether athletes returned before or after the 9-month mark following ACLR.

CONCLUSIONS

Completing rehabilitation and meeting objective criteria significantly increased the odds for male athletes to return to pivoting sports. Time to RTS did not impact the risk for a new knee or ACL injury if athletes met objective criteria.

Thessaly Graft Index: An Artificial Intelligence-Based Index for the Assessment of Graft Integrity in ACL-Reconstructed Knees

BACKGROUND

Magnetic resonance imaging (MRI) has proven to be a valuable noninvasive tool to evaluate graft integrity after anterior cruciate ligament (ACL) reconstruction. However, MRI protocols and interpretation methodologies are quite diverse, preventing comparisons of signal intensity across subsequent scans and independent investigations. The purpose of this study was to create an artificial intelligence (AI)-based index (Thessaly Graft Index [TGI]) for the evaluation of graft integrity following ACL reconstruction.

METHODS

The cohort study included 24 patients with an isolated ACL injury that had been treated with a hamstring tendon autograft and followed for 1 year. MRI was performed preoperatively and 1 year postoperatively. The clinical and functional evaluations were performed with use of the KT-1000 and with the following patient-reported outcome measures (PROMs): the Knee Injury and Osteoarthritis Outcome Score (KOOS), the International Knee Documentation Committee Subjective Knee Function form (IKDC), the Lysholm score, and the Tegner Activity Scale (TAS). An AI model, based on the YOLOv5 Nano version, was designed to compute the probability of accurately detecting, in the sagittal plane, a healthy ACL (on a percentage scale) and was trained on healthy and injured knees from the KneeMRI dataset. The model was used to assess the integrity of ACL grafts, with a maximum score of 100. The results were compared with the MRI assessment from an independent radiologist and were correlated with PROMs and KT-1000 laxity.

RESULTS

The mean preoperative and postoperative TGI scores were 64.21 ± 8.96 and 82.37 ± 3.53, respectively. A mean increase of 15% in the TGI scores was observed between preoperative and postoperative images. The minimum threshold for TGI to categorize a graft as healthy on the postoperative MRI was 79.21%. Twenty-two grafts were characterized as intact and 2 as reruptured, with postoperative TGI scores of 71% and 42%. The radiologist's assessment was in total agreement with the TGI scores. The correlation of the TGI ranged from moderate to good with the TAS (0.668), IKDC (0.516), Lysholm (0.521), KOOS total (0.594), and KT-1000 (0.561).

CONCLUSIONS

The TGI is an AI tool that is able to accurately recognize an ACL graft rupture. Moreover, the TGI correlated with the KT-1000 postoperative values and PROM scores.

LEVEL OF EVIDENCE

Diagnostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Early Measures of Torque Development are Related to Peak Torque at Six Months Following ACL Reconstruction

Background and Purpose

Individuals following anterior cruciate ligament reconstruction (ACLR) are at increased risk for subsequent anterior cruciate ligament (ACL) injury, with quadriceps strength deficits being a risk factor. While early measures of quadriceps strength can predict strength in the later stages of rehabilitation, it remains unclear whether isometric rate of torque development (RTD) is related to later outcomes. The purpose of this study was to examine the correlation between quadriceps RTD values at four months post-ACLR and quadriceps isokinetic peak torque values at six months post-ACLR. It was hypothesized that isometric RTD at four months would be significantly correlated with isokinetic peak torque at six months post-ACLR. A secondary hypothesis was that the involved limb RT would be significantly slower than the uninvolved limb at four months post-operative.

Study Design

Retrospective case series.

Methods

Forty-seven patients (22 males and 25 females) who had undergone ACLR performed isometric testing at four months and isokinetic testing at six months post-operatively. Isometric testing was utilized to measure torque from 0-100ms (RTD100) and from 100-200ms (RTD200), and isometric peak torque. Isokinetic testing was utilized to measure peak torque at 60°/sec and 180°/sec. Correlations between isometric and isokinetic measures were evaluated using Spearman's rho. RTD was compared between the involved and uninvolved limbs.

Results

The four-month measures of RTD100 (r=.55, r=.45), RTD200 (r=.63, r=.52), and peak isometric torque (r=.77, r=.64) were all significantly correlated with 60°/sec and 180°/sec isokinetic peak torque (p≤0.001), respectively. The involved limb rate of torque development was slower, and strength was lower than the uninvolved limb (p<0.001).

Conclusions

The hypotheses were supported as four-month isometric measures were moderately to strongly correlated to six-month isokinetic peak torque measures and the involved limb RTD was slower than the uninvolved limb. Incorporation of interventions focusing on development of force quickly is encouraged during rehabilitation.

Level of Evidence

3b.

Comparison of Postoperative Strength Progression and Outcomes Following Primary Versus Secondary ACL Reconstruction in the Young Athlete

BACKGROUND

Return to sport testing after ACL reconstruction (ACLR) is becoming increasingly popular. Anecdotally, some believe that patients who undergo a second ACL surgery on either the ipsilateral or contralateral leg progress through their rehabilitation goals faster the second time through. The purpose of this study was to evaluate the rate of strength progression in return to sport testing after primary and secondary ACLR surgeries in a young, active population.

METHODS

A retrospective review of patients who underwent ACLR between September 2013 and December 2022 was performed. Patients were included if they underwent an ACLR and completed at least 2 postoperative strength tests. Strength testing was commonly performed at 3, 6, and 9 months. Exclusion criteria included age older than 30 and those who had a contralateral graft harvest. Structural equation modeling was performed for each strength assessment by the timepoint it was performed. A linear combination of parameters was performed to compare the path coefficients between the primary and secondary ACL groups for each strength test to assess statistical differences in the rate of change of each strength test over time.

RESULTS

Three hundred ninety-six patients in the primary ACLR group and 50 patients in the secondary ACLR group met the inclusion criteria. Patients who received secondary ACL surgery were older, had a higher percentage of BTB grafts, lateral augments, and internal brace augments. Months from surgery had a significant positive correlation with nearly all strength tests in both groups. There was no difference between primary and secondary surgery in the progression of any postoperative strength test. There was no difference in progression of IKDC or RSI scores between groups.

CONCLUSION

This study suggests that patients who undergo a second ACL surgery do not progress their strength faster or slower than after primary ACLR. This implies that these patients do not require different return-to-play protocols from a strength perspective.

LEVEL OF EVIDENCE

Retrospective study, level III evidence.

Block or No-Block? Regional Anesthesia and Return-to-Sport Outcomes in Quadriceps Tendon Autograft ACL Reconstruction

This research aimed to compare return-to-sport (RTS) muscle strength testing in athletes 6 months following a quadriceps tendon (QT) autograft anterior cruciate ligament (ACL) reconstruction performed with or without a nerve block. Retrospective analysis of RTS strength testing in competitive or recreational athletes who had a QT ACL reconstruction at a Midwest academic referral center. There were 182 participants ranging from 12 to 29 years of age with a mean age of 16.9 years old. Patients were stratified into two groups based on whether they received an intraoperative nerve (adductor canal) block. Relevant tests performed during RTS testing included isokinetic quadriceps and hamstring strength (ISOK) in addition to limb symmetry and self-reported psychological readiness. Most patients underwent multiple RTS tests; for this study, we used the data from their initial test typically performed in the 6-month postoperative timeframe. Forty-three patients had an intraoperative nerve block, while 139 did not have a block. There were no observed statistically significant differences in quadriceps or hamstring strength when comparing the median scores of the nerve block and no-block groups across the major quantitative categories of isokinetic muscle strength, limb symmetry, tuck jump errors, or psychological readiness to return to sport. There was evidence of a relationship between increased graft thickness and decreased isokinetic quadriceps strength at both 60 and 300 deg/s in addition to lower self-reported confidence in readiness to RTS. No significant differences in functional strength testing or psychological readiness at 6 months were seen in ACL reconstruction involving QT grafts based on block status. There was evidence of a relationship between increased QT autograft thickness and decreased functional outcomes at 6 months. This research strengthens the case for leveraging an adductor canal block in QT ACL reconstruction involving young athletes as an effective tool for pain management without compromising muscle strength or RTS readiness. The level of evidence is III.

Late-stage rehabilitation effects do not differ between quadriceps and hamstring tendon autograft after anterior cruciate ligament reconstruction: a multicentre propensity score-matched case-control intervention trial

Late-stage rehabilitation interventions after an anterior cruciate ligament (ACL) reconstruction are under-researched, inter alia regarding potential differences in rehabilitation effects between autograft types. This study determined the effectiveness of a specific, late-stage rehabilitation to usual care after ACL reconstructions in patients with a quadriceps versus such with a hamstring tendon autograft. In this multicentre case-control intervention study, participants aged 18-35 years were included at the end of their formal rehabilitation (mean 8.1 months) after ACL reconstruction. Twenty-four cases with an arthroscopically assisted, anatomic ipsilateral quadriceps femoris tendon autograft and two numerically equal hamstring tendon reconstructed propensity score-matched groups were compared. Matching variables were gender, age, Tegner activity scale, plus, once, the time since reconstruction and once the functional capacity at intervention onset. All participants performed a 5-month performance enhancing intervention. All outcomes were measured once a month. Self-reported outcomes such as knee function (The Knee injury and Osteoarthritis Outcome Score (KOOS) Sport as the main self-reported outcome) were followed by a series of hop and jump tests. The front hops for distance (outcome: hopping distance) was the primary outcomes of the study. Linear mixed models were calculated using change scores. All participants were analysed. No group*time interaction effect could be identified in the two main outcomes KOOS SPORT and front hop for distance. Furthermore, with the exception of the self-reported all-day function, no outcome displayed any between-group differences in the trainability, either. The return-to-sport success took a mean time of 3.8 months after study commencement; the success rates ranged between 80% and 83% and were not different between groups. Being reconstructed with a hamstrings or with a quadriceps tendon autograft had no impact on the late-stage rehabilitation effects after an ACL rupture. Both graft choices enable comparably favourable functional outcomes and return-to-sport success rates. Conversely, no recommendation can be derived with regard to the selection of either a hamstring or a quadriceps autograft type. The decision must be undertaken individually and based on other factors.

Return-to-sport tests: Do they reduce risk of re-rupture after anterior cruciate ligament reconstruction?

INTRODUCTION

Anterior cruciate ligament (ACL) rupture is one of the most common knee injuries. Despite the effectiveness of reconstruction, re-rupture rates of up to 15 ​% have been reported. Static and dynamic test of strength and movement control have been used to determine when return to sports (RTS) is appropriate.

OBJECTIVE

To determine whether successfully passing return to sport (RTS) tests reduces the re-rupture rate.

METHODS

Retrospective cohort study. Patients who underwent ACL reconstruction (ACLR) from June 2018 to May 2023, and who performed RTS tests after rehabilitation, were analyzed. Patients who, in addition to ACLR, underwent extra-articular tenodesis, osteotomy, or multiligament injuries were excluded. RTS tests included the following: repeat sprint ability, dynamic valgus, proagility, unilateral counter movement jump (CMJ), isokinetic, triple hop test, and functional movement screen (FMS). All statistical analyses were performed with STATA version 18.0.

RESULTS

Ninety five patients underwent RTS tests after ACLR, with a follow-up time of 27.8 months. 71.6 ​% of patients were men with a mean age of 25.15 ​± ​10.7 years. The overall re-rupture rate was 13.68 ​% (13 patients). When comparing patients who passed and did not pass the RTS tests, there were no differences by sex (p ​= ​0.06) or age (p ​= ​0.11). The only statistically significant difference between the groups was the mean risk score (passed: 11.5 ​± ​0.7 vs. not passed: 15.5 ​± ​2.1; p ​< ​0.001). Patients with re-rupture were more likely to be from the non-passed group (passed: 0 ​% v/s not passed: 18.1 ​%; p ​= ​0.03), with a statistical power of 0.70.

CONCLUSION

Our records show that passing RTS test after an ACLR could guarantee the absence of re-rupture in the medium term.

LEVEL OF EVIDENCE

Level IV.

Reliability and Validity of a Crane Scale for Isometric Knee and Shoulder Strength Assessment

Background

Due to cost barriers and/or space constraints, electromechanical and hand-held dynamometry are underutilized in rehabilitation settings. As a result, clinicians often rely on semi-quantitative methods that may fail to detect deficits in upper or lower extremity strength. The purpose of this study was to examine the between-trials test-retest reliability and concurrent criterion validity of an accessible crane scale for measuring isometric knee and shoulder strength.

Study Design

Observational cohort, Cross-sectional study.

Methods

Twenty healthy, recreationally active adults underwent isometric knee and shoulder strength testing using a crane scale, electromechanical dynamometer, and hand-held dynamometer during a single session. Knee extension and flexion, and shoulder internal rotation, external rotation, and abduction were tested. Three maximal effort trials were performed per device and motion, with the order of device testing randomized. Between-trials test-retest reliability of the crane scale was assessed using intraclass correlation coefficients (ICCs). Concurrent criterion validity was examined using ICCs, absolute and relative error, Bland-Altman plots, and simple linear regression.

Results

Test-retest reliability of the crane scale was excellent for all motions (ICCs ≥ 0.90). Concurrent validity was poor to moderate with the electromechanical dynamometer (ICCs = 0.36-0.72) but excellent with the hand-held dynamometer (ICCs ≥ 0.90). There was a negative bias for the crane scale compared to alternative devices and evidence of a proportional bias for knee extension and shoulder abduction.

Conclusions

A crane scale provides values similar to hand-held dynamometry but is not comparable to results from electromechanical dynamometry. The lack of concurrent validity between the crane scale and electromechanical dynamometry may be partially attributable to differences in stabilization and participant positioning.

Level of Evidence

3b, reliablity and validity study.

Efficacy of complex decongestive therapy in managing limb swelling, pain, and enhancing functional recovery after arthroscopic reconstruction of anterior cruciate ligament

OBJECTIVE

To evaluate the efficacy of Complex Decongestive Therapy (CDT) in managing limb swelling, alleviating pain, and promoting functional recovery in patients following anterior cruciate ligament reconstruction (ACLR).

METHOD

This was a randomized controlled trial (RCT) involving 160 patients who underwent ACLR at a tertiary hospital in Shenzhen between August 2021 and April 2023. The study compared the outcomes of conventional nursing care with complex decongestive therapy (CDT). The differences in leg circumference, Visual Analog Scale (VAS) pain scores, and Active Range of Motion (AROM) were assessed at six time points during the perioperative period and up to 30 days post-surgery.

RESULTS

This study included 69 patients in the experimental group and 64 patients in the control group. After one month of treatment with CDT, significant differences in calf circumference were observed between the experimental and control groups on the 3rd (t = -2.083, P = 0.039) and 5th (t = -2.078, P = 0.040) postoperative days. Regarding changes in central patellar circumference, a significant difference was noted on the 5th postoperative day (t = -2.092, P = 0.038) in the experimental group. However, no significant differences in thigh circumference were observed at any of the six time points (P > 0.05). Visual analog scale (VAS) pain scores were significantly different on the 1st (t = -1.978, P = 0.048) and 3rd (t = -2.530, P = 0.011) postoperative days. Lysholm scores showed a significant difference between the groups on the 30th postoperative day (t = -3.438, P = 0.001), with no significant difference observed before surgery (P > 0.05). Significant differences in AROM were found on the 14th (t = -3.919, P = 0.000) and 30th (t = -2.615, P = 0.009) postoperative days.

CONCLUSION

CDT can effectively reduce limb swelling on the 3rd and 5th postoperative days, alleviate pain on the 1st and 3rd postoperative days, and enhance joint functional recovery on the 14th and 30th postoperative days.

Blood Flow Restriction Enhances Recovery After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating neuromuscular and clinical outcomes of blood flow restriction (BFR) training after anterior cruciate ligament reconstruction (ACLR) compared with non-BFR rehabilitation protocols.

METHODS

A systematic review was performed in accordance with the 2020 Preferred Reporting Items for Systematic reviews and Meta Analyses guidelines by querying PubMed, MEDLINE, Scopus, the Cochrane Database for Systematic Review, and the Cochrane Central Register for Controlled Trials databases from inception through December 2023 to identify Level I and II RCTs evaluating outcomes of BFR training after ACLR compared with non-BFR rehabilitation. A meta-analysis was performed using random-effects models with standardized mean difference (SMD) for pain, muscle strength, and muscle volume, whereas mean difference was calculated for patient-reported outcome measures.

RESULTS

Eight RCTs, consisting of 245 patients, met inclusion criteria, with 115 patients undergoing non-BFR rehabilitation compared with 130 patients undergoing BFR after ACLR. Mean patient age was 27.2 ± 6.7 years, with most patients being male (63.3%, n = 138/218). The length of the BFR rehabilitation protocol was most commonly between 8 and 12 weeks (range, 14 days to 16 weeks). Most studies set the limb/arterial occlusion pressure in the BFR group at 80%. When compared with non-BFR rehabilitation, BFR resulted in significant improvement in isokinetic muscle strength (SMD: 0.77, P = .02, I2: 58%), International Knee Documentation Committee score (mean difference: 10.97, P ≤ .00001, I2: 77%), and pain (SMD: 1.52, P = .04, I2: 87%), but not quadriceps muscle volume (SMD: 0.28, P = .43, I2: 76%).

CONCLUSIONS

The use of BFR after ACLR led to improvements in pain, International Knee Documentation Committee score, and isokinetic muscle strength, with variable outcomes on the basis of quadriceps strength, volume, and thickness when compared with non-BFR rehabilitation.

LEVEL OF EVIDENCE

Level II, systematic review and meta-analysis of Level I and II studies.

Combining a digital health application with standard care significantly enhances rehabilitation outcomes for ACL surgery patients

INTRODUCTION

Anterior cruciate ligament (ACL) rupture is one of the most common sports injuries. Regardless of the surgical treatment, patients require intensive education about the pathology, therapeutic options and physical therapy. However, it is often not possible for the patient to start physical therapy directly and schedule adequate consultations. Digital health applications are medical devices that can help bridge the gap between physiotherapy sessions and provide qualified, convenient and effective education and treatment. This study is needed to explore alternative methods to ensure continuous and effective rehabilitation for ACL patients who face delays in accessing traditional physiotherapy. The study aimed to compare app-assisted therapy plus standard of care (conventional orthopaedic and physiotherapeutic measures) versus isolated standard of care for patients with planned ACL surgery.

METHODS

A monocentric, two-arm, 1:1 randomized controlled study examined 80 patients after a cruciate ligament rupture with or without meniscal injury. Patients over 18 years with a confirmed diagnosis of ACL rupture and planned surgical reconstruction using autologous grafts were included. The study criteria additionally included willingness to use the Orthopy app and sufficient German language proficiency. The study excluded patients with severe concomitant injuries, prior knee surgeries, chronic pain conditions and those not compatible with app usage. Patients were randomized and their baseline data (t0) was collected. Subsequently, they received their treatment according to their treatment group. The study included a presurgery period (2-6 weeks) and a postsurgery period (14 weeks). Interim assessments were done via online questionnaires at t1 (if more than 3 weeks before surgery) and t3, t4 and t5 (postsurgery). Additional clinical assessments were conducted at t2 (presurgery) and t6 (14 weeks postsurgery). Primary outcome measures included the knee injury and osteoarthritis outcome score (KOOS), with subjective pain and function levels (numeric rating scale [NRS]) as secondary endpoints.

RESULTS

The clinical trial was able to show positive outcomes on the KOOS Pain and Symptoms subscale of the primary endpoint KOOS in the interventional group compared to the standard of care group. A statistically significant pain reduction could be seen at t1 (p = 0.0005), t2 (p = 0.0068) and t4 (approximately 6 weeks after surgery; p = 0.01). A significant reduction of symptoms at t1 (p = 0.0001), t2 (p = 0.0036) and t6 (p = 0.0377) were recognized. These findings are further supported by the significant benefit of the pain NRS at t4 and positive tendencies at t3, t5 and t6. The KOOS subscales quality of life (p = 0.0066), activities of daily living (p = 0.0009) and Sport (p = 0.0484) showed significant effects before surgery.

CONCLUSION

The Orthopy app is a medical device that is both safe and effective for use. Combining the Orthopy app and standard of care can significantly improve prehabilitation and rehabilitation in surgical treatment with ACL reconstruction compared with the isolated standard of care.

LEVEL OF EVIDENCE

Level I.

Anterior Cruciate Ligament Return to Play: "A Framework for Decision Making"

Anterior cruciate ligament (ACL) injury is common in athletic individuals and often leads to physical impairments, a low rate of return to performance, reinjuries, and sometimes reductions in career length [...].

Age not a primary risk factor for ACL injury-A comprehensive review of ACL injury and reinjury risk factors confounded by young patient age

Revision surgery after anterior cruciate ligament reconstruction (ACL-R) is hypothesized to be the result of an interplay between factors associated with the anatomy, physiological characteristics and environment of the patient. The multifactorial nature of revision ACL-R risk is difficult to quantify, and evidence regarding the independent roles of potentially important variables is inconsistent throughout the literature. Young patient age is often cited as one of the most prominent risk factors for reinjury after ACL-R. However, the association between a non-modifiable variable such as patient age and revision ACL-R risk is likely to be a spurious correlation due to the confounding effect of more important variables. From the perspective of healthcare professionals aiming to mitigate revision ACL-R risk through targeted interventions, awareness of factors like generalized joint hypermobility, bone morphology, muscle strength imbalances, and genetic factors is critical for the individualized risk assessment of patients with ACL injury. The aim of this current concepts article is to raise awareness of the essential anatomical, physiological, and activity-related risk factors associated with ACL injury and reinjury risk that are likely captured and confounded by patient age. LEVEL OF EVIDENCE: Level V.

Positive impact of patient participation in arthroscopic anterior cruciate ligament reconstruction surgery on clinical and functional outcomes, rehabilitation and patient satisfaction

BACKGROUND

This study aimed to evaluate the effect of patient participation on clinical and functional outcomes, satisfaction, and compliance with postoperative rehabilitation in patients undergoing surgery for anterior cruciate ligament (ACL) injury.

METHODS

Sixty-one patients who underwent isolated ACL reconstruction (ACLR) were included. Thirty patients in the participation group were shown the arthroscopy screen and allowed to communicate with the surgeon during surgery. For clinical and functional evaluation, knee joint range of motion (ROM), International Knee Documentation Committee Subjective Knee Form (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Lysholm Knee Scoring Scale (LKSS), Short Form-36 (SF-36) score, and Tegner Activity Scale (TAS), were used. The Pain Quality Assessment Scale was used to assess pain. Additionally, the patient's satisfaction and exercise compliance were evaluated using a 5-point Likert scale and percentage of exercise participation, respectively.

RESULTS

At 3rd week, the ROM, SF-36, LKSS values, and pain scores were better in the participation group compared to the control group(p <.05). At 6th month, the IKDC, KOOS, SF-36 values and pain scores were also better in the participation group compared to the control group (p <.05). However, the ROM, LKSS, and TAS values were similar between groups at the 6th month(p >.05). Postop satisfaction at 3rd week and 6th month and exercise compliance postoperatively were significantly better in the participation group compared to the control group(p <.05).

CONCLUSION

Patient participation during ACLR surgery by communicating with the surgeon positively affects clinical and functional outcomes. It also contributes to patient satisfaction and compliance with the rehabilitation program postoperatively.

CLINICAL TRIAL NUMBER

Not Applicable.

Rehabilitation volume, psychological readiness, and motor function are important factors for a successful return to sport after anterior cruciate ligament reconstruction: A 2-year follow-up cohort study

OBJECTIVES

To find contributors to return to sport success or time until return to sport in individuals after an anterior cruciate ligament reconstruction.

DESIGN

Cohort study.

METHODS

Secondary analysis of the data of two intervention studies.

PARTICIPANTS

We included adults < 36 years of age with a tendon autograft anterior cruciate ligament reconstruction who were active in any type of sport prior to the injury and aiming to return to sport. All participants were prospectively monitored for 24 months.

INTERVENTIONS

At the end of the individual post-surgery rehabilitation and re-injury prevention programmes, self-report- and objective functional outcomes were quantified.

MAIN OUTCOME MEASURES

The potential return to sport success (return to the same type of sports, frequency, intensity, and quality of performance as pre-injury), secondary injuries, and all rehabilitation and training measures were prospectively monitored. To determine the contributing factors, Cox regressions for traits and baseline factors and a logistic mixed model, which also included prospective time-dependent factors, were calculated.

RESULTS

203 participants were included; 104 (51 % of the total sample and 68 % of the full cases) successfully returned to their sporting activity. The median duration until return to sport was 302 days (interquartile range was 114 days). Contributing factors were the type of working (blue- vs. white collar: odds ratio for return to sport = 0.51 [95 % confidence interval = 0.29 to 0.90]) and the athletic status (elite vs. non-elite: odds ratio = 2.28 [1.03 to 5.03]). Prospectively, higher rehabilitation volumes until the end of the rehabilitation were predictive for return to sport success: the odds ratio per additional hour of rehabilitation was 1.004 [1.001 to 1.006]. Functional abilities such as the normalised knee separation distance during drop jump landing (odds ratio = 0.961 [0.924 to 0.999]) were predictive at a later stage, at the end of the re-injury prevention. Psychological readiness for return to sport was predictive at most of the timepoints: those who were confident to return to sport were more successful to return to sport at the end of the rehabilitation (odds ratio = 1.029 [1.004 to 1.056]) and at the end of the re-injury prevention (odds ratio = 1.038 [1.004 to 1.073]).

CONCLUSIONS

The most important factors for a successful pre-injury-level return to sport after anterior cruciate ligament reconstruction were the exercise volume, psychological readiness and functional hop/jump abilities. Whilst the impact of these modifiable factors was robust against multilevel modelling, the impact of athletic and working status vanishes when the prospective factors are included.

Tale of quadriceps and hamstring muscle strength after ACL reconstruction: a systematic review with longitudinal and multivariate meta-analysis

OBJECTIVE

This study aimed to investigate how knee extensor and flexor strength change over time after anterior cruciate ligament reconstruction (ACLR).

DESIGN

Systematic review with longitudinal meta-analysis.

DATA SOURCES

Medline, Embase, CINAHL, Scopus, Cochrane CENTRAL and SPORTDiscus to 28 February 2023.

ELIGIBILITY CRITERIA

Studies of primary ACLR (n≥50), with mean participant age 18-40 years, reporting a quantitative measure of knee extensor or flexor strength were eligible. Muscle strength had to be reported for the ACL limb and compared with: (1) the contralateral limb (within-person); and/or (2) an uninjured control limb (between-person).

RESULTS

We included 232 studies of 34 220 participants. Knee extensor and flexor strength showed sharp initial improvement postoperatively before tailing off at approximately 12-18 months post surgery with minimal change thereafter. Knee extensor strength was reduced by more than 10% compared with the contralateral limb and approximately 20% compared with uninjured controls at 1 year for slow concentric, fast concentric and isometric contractions. Knee flexor strength showed smaller deficits but was still 5%-7% lower than the contralateral limb at 1 year for slow concentric, fast concentric and isometric contractions. Between-person comparisons showed larger deficits than within-person comparisons.

CONCLUSION

Knee extensor muscle strength is meaningfully reduced (>10%) at 1 year, with limited improvement after this time up to and beyond 5 years post surgery. Many people likely experience persistent and potentially long-term strength deficits after ACLR. Comparison within person (to the contralateral limb) likely underestimates strength deficits in contrast to uninjured controls.

Questioning the rules of engagement: a critical analysis of the use of limb symmetry index for safe return to sport after anterior cruciate ligament reconstruction

OBJECTIVE

To evaluate the association between limb symmetry index (LSI) in quadriceps and hamstrings strength together with hop tests, as a proxy of recovery, and the deviation from being symmetrical (LSI 100%), with a safe return to sport (RTS) after anterior cruciate ligament reconstruction (ACL-R).

METHODS

Athletes between 15 and 30 years old with a preinjury Tegner activity level ≥6 were eligible for inclusion. Data were extracted from a rehabilitation-specific registry, Project ACL (Gothenburg, Sweden) at the time of or after RTS for each athlete. The outcome of interest in this study was a safe RTS-not suffering a second ACL injury within 2 years from RTS-addressed by using the LSI in five different ways with results from the test battery which include five tests of muscle function at or after the time of RTS. Logistic regression analyses were performed with safe RTS as a dependent variable and presented with ORs and 95% CIs.

RESULTS

In total, 233 athletes (51.1% women) were included. The best-differentiating cut-offs for strength and hop tests showed non-significantly poor discriminatory ability between athletes who had a safe RTS and those who did not (Youden J 0.09-0.24 and area under the curve 0.50-0.59). Athletes who had ≥80% or ≥85% LSI had significantly lower odds of safe RTS compared with athletes who did not meet the cut-offs of safe RTS (OR=0.32 (95% CI 0.12 to 0.87) and OR=0.39 (95% CI 0.18 to 0.84), respectively). There was no effect of a 1% increase in LSI or deviation from 100% symmetry on safe RTS.

CONCLUSION

The use of LSI from tests of muscle function to determine safe RTS after ACL-R, that is, RTS without sustaining a second ACL injury within 2 years, cannot differentiate between athletes who had a safe RTS and those who did not, regardless of whether LSI was used as cut-offs, incremental or as deviation from symmetry. Thus, it is of clinical importance that clinicians do not solely rely on the LSI to clear athletes for RTS.

Quantifying Muscle Volume Deficits Among 38 Lower Extremity Muscles in Collegiate Football Athletes After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Quadriceps dysfunction is ubiquitous after anterior cruciate ligament (ACL) reconstruction (ACLR). Addressing quadriceps dysfunction is crucial to improve function, reduce the reinjury risk, and maintain long-term knee health. While deficits specific to the quadriceps are well documented, less is known about the effect of an ACL injury on other lower extremity muscle groups.

PURPOSE/HYPOTHESIS

The purpose of this exploratory analysis was to quantify and rank lower extremity muscle volume deficits using magnetic resonance imaging in collegiate football athletes after ACLR. It was hypothesized that the quadriceps muscles would present with the greatest deficits and that compensatory hypertrophy of muscles at adjacent joints such as the hip and ankle would be observed.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

This study is a secondary analysis from an ongoing multicenter prospective cohort study involving Division I collegiate football athletes. Athletes who underwent primary unilateral ACLR (1 [3%] allograft, 2 [7%] quadriceps tendon autograft, 22 [73%] bone-patellar tendon-bone autograft, 5 [17%] hamstring tendon autograft) and magnetic resonance imaging were included. Muscle volumes (mL·kg-1·m-1) were quantified bilaterally from 38 lower extremity muscles using machine learning technology. Paired-samples t tests were performed between limbs for each muscle, which were then ranked and visualized in a forest plot based on standardized mean differences (surgical - nonsurgical limb).

RESULTS

A total of 30 athletes (mean time from surgery, 27.9 ± 19.0 months) were included. The largest muscle volume deficits in the surgical limb were seen in the 3 uniarticular quadriceps muscles, followed by the biarticular triceps surae muscles. The rectus femoris and soleus did not show significant differences between limbs. Conversely, the fibularis muscle group had a greater muscle volume in the surgical limb compared with the nonsurgical limb. Most other muscle groups did not present significant differences between limbs.

CONCLUSION

Persistent quadriceps atrophy in a cohort of high-level athletes over 2 years after ACLR was highlighted in this study. Deficits in the gastrocnemius muscles, but not in the soleus, were also identified. This comprehensive approach examining various lower extremity muscles revealed latent muscle volume deficits present after ACLR.

Does It Matter? Isometric or Isokinetic Assessment of Quadriceps Strength Symmetry 9 Months After ACLR in Collegiate Athletes

BACKGROUND

Greater quadriceps strength symmetry is associated with better outcomes after anterior cruciate ligament reconstruction (ACLR). Isometric and isokinetic assessments of quadriceps strength inform therapeutic exercise prescription and return-to-sport decisions. It is unclear whether isometric and isokinetic measures provide similar information post-ACLR.

HYPOTHESIS

Quadriceps strength symmetry is similar between isometric and isokinetic assessments. Isokinetic and isometric strength symmetries have similar associations to functional knee kinetics and self-reported knee function.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

NCAA Division I athletes (N = 35), 8.9 ± 2.5 months post-ACLR completed isometric and isokinetic quadriceps strength assessments, countermovement jumps (CMJs), and treadmill running. Self-reported knee function was assessed using the International Knee Documentation Committee Subjective Knee Form (IKDC). Agreement between isometric and isokinetic strength symmetry was assessed using Bland-Altman analysis, with associations to functional knee kinetics and IKDC assessed using Pearson correlations and linear regressions.

RESULTS

Mean difference in quadriceps strength symmetry between isokinetic and isometric assessments was 1.0% (95% limits of agreement of -25.1% to 23.0%). Functional knee kinetics during running and CMJ were moderately to strongly associated with isometric strength symmetry (r = 0.64-0.80, P < 0.01) and moderately associated with isokinetic strength symmetry (r = 0.41-0.58, P < 0.01). IKDC scores were weakly to moderately associated with isometric (r = 0.39, P = 0.02) and isokinetic (r = 0.49, P < 0.01) strength symmetry.

CONCLUSION

Isokinetic and isometric assessments of quadriceps strength symmetry in collegiate athletes 9 months post-ACLR demonstrated strong agreement. Quadriceps strength symmetry is associated with functional knee kinetic symmetry post-ACLR.

CLINICAL RELEVANCE

Considerable individual variation suggests mode of contraction should be consistent throughout postoperative assessment. Isometric strength symmetry may be a better indicator of functional knee kinetic symmetry, while isokinetic strength symmetry may be associated more closely with patient-reported outcomes.

High Return to Competition Rate After On-Field Rehabilitation in Competitive Male Soccer Players After ACL Reconstruction: GPS Tracking in 100 Consecutive Cases

Background

Despite published guidelines describing on-field rehabilitation (OFR) frameworks for soccer, available evidence for practitioners who work with players with anterior cruciate ligament reconstruction (ACLR) is limited.

Purpose

To document the activity and workloads completed by a large cohort of amateur and professional soccer players during OFR following ACLR after completing their indoor rehabilitation and to establish their return to competition (RTC) outcomes.

Study Design

Case series; Level of evidence, 4.

Methods

OFR measurements/activities, global positioning system (GPS), and heart rate data were collected from 100 male 11-a-side soccer players with ACLR undergoing a criteria-based rehabilitation process, concluding with a 5-stage OFR program. Consent was obtained directly from the players involved in this study before completing a follow-up questionnaire to document RTC outcomes. Differences between the level of play (professional and amateur) and 5 OFR stages were investigated using separate linear mixed models.

Results

A minimum 9-month follow-up was possible for 97 players (97%), with a median time of 2.3 years after ACLR and 84% RTC, with higher rates in professionals (100%) than amateurs (80%). Ten (10%) players sustained an ACL reinjury. Professionals completed more OFR sessions (20.6 ± 7.7 vs 13.2 ± 7.7; P < .001) over a shorter period (44.7 ± 30.3 vs 59.3 ± 28.5 days; P = .044) and achieved higher workloads mostly in the high-intensity GPS metrics in each OFR stage. Typical external workload outputs in the final OFR stage aligned with team training demands for the total distance (TD) (106%), high-intensity distance (HID) (104%), peak speed (PS) (88%), acceleration distance (ACC) (110%), and deceleration distance (DEC) (48%), but they were lower compared with match play demands (TD: 44%; HID: 51%; PS: 82%; ACC: 63%; and DEC: 26%).

Conclusion

High RTC rates were reported in those players who participated in OFR after indoor rehabilitation. Completion of all five OFR stages almost prepared them for team training demands; however, workloads remain low compared to match play.

Hop distance to body height ratio outperforms limb symmetry index in predicting second anterior cruciate ligament injury

PURPOSE

The ability of current return-to-sport (RTS) tests to predict second anterior cruciate ligament (ACL) injuries (ACLI) in athletes with a history of ACL reconstruction (ACLR) is unclear. This study aimed to prospectively assess the risk of a second ACLI by identifying the most significant deviation in hop test results in professional athletes after ACLR compared to healthy peers.

METHODS

A total of 30 professional athletes with a history of ACLR and 30 healthy professional athletes participated in this study. Participants performed 10 functional hop tests, and the subsequent limb symmetry index (LSI) was compared between the groups. After a 3-year follow-up, the re-injury rate was assessed among the ACLR group. Fourteen ACLR athletes who sustained a second ACLI were included and matched with 14 controls from the healthy group. The LSI and the hop distance to body height percentage (D/H) were compared between the groups.

RESULTS

Statistical analyses confirmed a significant decrease in LSI in the ACLR group compared to the healthy group in the triple hop for distance (p = .023). In re-injured ACLR athletes, seven different hop tests showed a significant decrease in the D/H index compared to the healthy controls. Meanwhile, for LSI, only the triple cross-over hop for distance (p = .045) showed a significant increase in the healthy group.

CONCLUSION

Before clearing athletes for RTS, assessing functional hop test results using the hop distance to body height ratio, aligned with normative data from healthy controls, could further enhance the prediction of reduced graft rupture risk.

LEVEL OF EVIDENCE

Level I.

Patients undergoing multiligament knee reconstruction injured during pivoting sports demonstrate similar clinical, functional and return to sport outcomes by 2 years compared with those undergoing anterior cruciate ligament reconstruction

PURPOSE

This study investigates the clinical and activity-based outcomes after anterior cruciate ligament reconstruction (ACLR) versus multiligamentous knee reconstruction (MLKR) following a pivoting sports injury.

METHODS

Fifty MLKR patients were included, of which 20 (40%) were injured during pivoting sports. A further 50 patients undergoing ACLR following an injury during pivoting sports were consecutively recruited for comparison. Patients were assessed before the surgery and at 6-, 12- and 24 months with patient-reported outcome measures (PROMs) including the International Knee Documentation Committee (IKDC) form, Tegner activity scale (TAS) and anterior cruciate ligament return to sport after injury (ACL-RSI) score. Knee movement, the single (SHD) and triple (THD) hop tests for distance, and peak isokinetic knee extensor and flexor strength were assessed, with Limb Symmetry Indices (LSIs) calculated. Outcomes were compared across groups: (1) ACLR (n = 50), (2) MLKR (n = 50) and (3) MLKR due to pivoting sport injury (n = 20).

RESULTS

IKDC, TAS and ACL-RSI scores remained lower (p < 0.05) in the full MLKR versus ACLR cohort at all timepoints. Comparing the ACLR and MLKR cohort that had injuries specifically during pivoting sports, the IKDC (p < 0.001) and TAS (p = 0.009) were higher in the ACLR group at 6 months, and the ACL-RSI was higher at 6 (p < 0.001) and 12 (p = 0.007) months, there were no further differences. Hop and knee extensor strength LSIs were lower (p < 0.05) in the full MLKR (versus ACLR) cohort at all timepoints (apart from the 24-month SHD LSI). However, the ACLR group only demonstrated greater LSIs than the pivoting sport MLKR for the SHD at 6 months (p < 0.001), and knee extensor strength at 6 (p < 0.001) and 12 (p < 0.001) months.

CONCLUSIONS

While the recovery of patients undergoing MLKR due to a pivoting sports injury is delayed compared with their ACLR counterparts, the clinical outcome and activity profile are similar by 24 months.

LEVEL OF EVIDENCE

Level IV.

Delayed Anterior Cruciate Ligament Reconstruction Is Associated With Lower Odds of Returning to Preinjury Physical Activity Level at 12 Months Follow-Up

PURPOSE

To examine the effects of timing of anterior cruciate ligament (ACL) reconstruction on the odds to recover muscle (quadriceps and hamstring) strength, return to preinjury physical activity level, and achieve rehabilitation goals at 12 months follow-up.

METHODS

Data were extracted from a local rehabilitation registry in Sweden in November 2023. Patients ≥16 years old who underwent primary ACL reconstruction with hamstring tendon autografts, who underwent isokinetic muscle strength assessment, and responded to patient-reported outcomes 12 months after surgery were included. A multivariable logistic regression analysis was used to analyze the association between timing of ACL reconstruction and the recovery of muscle strength, return to preinjury physical activity level, and achievement of rehabilitation goals. The results of the logistic regression analysis were expressed as odds ratios for every 1-unit increase in the predictor variable (months between ACL injury and reconstruction).

RESULTS

In total, 715 patients were included, of whom 53.4% (n = 383) were women. The mean age at ACL reconstruction was 28.3 ± 10.5 years, and the median time between ACL injury to reconstruction was 4.9 months (interquartile range [IQR] 2.9-9.4). Delayed ACL reconstruction significantly decreased the odds of returning to preinjury physical activity level at 12 months in patients with a Tegner score of 6-10 (odds ratio 0.97; 95% confidence interval 0.94-0.99, P = .009), regardless of age. Shorter median time in months from ACL injury to reconstruction was observed for patients who returned to preinjury physical activity level, especially in younger patients (16-30 years old) (3.9 [IQR 2.5, 6.5] vs 4.7 [IQR 2.9, 9.1], P = .007) and in patients who participated in pivoting activities (Tegner scale 6-10) preinjury (3.4 [IQR 2.3, 6.2] vs 5.0 [IQR 2.9, 9.7], P < .001).

CONCLUSIONS

Delayed ACL reconstruction reduces the odds of returning to preinjury physical activity level in patients active in pivoting activities preinjury (Tegner 6-10), regardless of age, 12 months after surgery.

LEVEL OF EVIDENCE

Level III, retrospective study.

Functional Knee Stability in Elite Field Hockey Depends on Playing Class and Gender

Field hockey, a physically demanding Olympic sport, carries a high risk of lower limb injuries, yet data on injury risk in elite field hockey are limited. Functional knee stability is important for injury prevention and a safe return to sport. This study is the first to investigate functional knee stability in elite field hockey, considering gender and playing class, and establishes reference data for functional knee stability by using a standardized test battery that assesses one- and two-legged stability, jumping tests, speed, and agility. Seventy-two elite field hockey players, 30 males and 42 females (age 19.82±3.74 years) were divided into High Playing Class (HPC) and Moderate Playing Class (MPC). HPC players showed significantly better performance in all functional tests except balance tests ( p <0.01-0.024). Females showed significantly better one- and two-leg stability ( p <0.01) with lower injury rates, indicating the relevance of gender considerations. The study emphasizes the importance of balance and stability in the prevention of lower limb injuries in Olympic field hockey and also highlights the importance of considering pre-existing deficits in functional knee capability when assessing athletes for return to sport. These results can help improve athletic performance, identify individual strengths and weaknesses, prevent injury or re-injury, and facilitate return to sport after injury.

The Impact of a Concomitant Meniscus Surgery on Hop Performance Symmetry in Patients Rehabilitating After Anterior Cruciate Ligament Reconstruction

Background

Meniscus injuries often accompany anterior cruciate ligament (ACL) tears. However, little is known about how different surgical approaches to treat concomitant meniscus injuries impact hop performance after ACL reconstruction. Purpose: The purpose of this study was to compare hop test inter-limb symmetry for patients who had undergone ACL reconstruction without an associated meniscal surgery, patients who had undergone ACL reconstruction with a meniscus repair, and patients who had undergone ACL reconstruction with a partial meniscectomy.

Study Design

Cross-sectional study.

Methods

Hop test data collected at the time of return-to-sport testing (average of 6.4 ± 1.4 months after surgery) was extracted from electronic medical records for 192 patients who had undergone ACL reconstruction. Of these patients, 102 had undergone an isolated ACL reconstruction, 60 had undergone an ACL reconstruction along with a meniscus repair, and 30 had undergone an ACL reconstruction along with a partial meniscectomy. Analysis of variance was used to compare limb symmetry indices for the single- and triple-hop tests. These limb symmetry indices reflected the ratio of the hop distance for the involved limb relative to the uninvolved limb, expressed as a percentage.

Results

The sample was comprised of 100 males and 92 females. Their average age was 20.6 ± 8.2 years. There were significant differences among the groups for the single-hop test (p = 0.031) and triple-hop test (p = 0.024) limb symmetry indices. For both tests, the patients who had undergone ACL reconstruction with a partial meniscectomy tended to exhibit greater deficits in hop performance for their involved limb (relative to their uninvolved limb), compared to those without a meniscal injury and those who had undergone meniscus repair.

Conclusions

The results of this study suggest that patients who undergo ACL reconstruction along with a partial meniscectomy tend to experience less complete and/or delayed recovery of involved-limb hop performance, which could reflect more persistent deficits in lower body power.

Level of Evidence

3.

Hamstrings and Quadriceps Weaknesses Following Anterior Cruciate Ligament Reconstruction Persist Up to 6 Months After Return-to-Sport: An Angle-specific Strength Analysis

BACKGROUND

Hamstrings and quadriceps strength recovery and restoration of the hamstrings-to-quadriceps ratio (H/Q ratio) is a major concern after anterior cruciate ligament reconstruction (ACLR). Recently, moment-angle profiles and angle-specific H/Q ratios are receiving increasing interest.

PURPOSE

The first objective of this study was to investigate moment-angle profiles and angle-specific H/Q ratio profiles in athletes with ACLR at the time of RTS. The second objective of this study was to assess whether strength asymmetries identified at the time of RTS, persist after six months.

STUDY DESIGN

Case-Control study.

METHODS

Twenty athletes who had undergone ACLR performed isokinetic strength tests for concentric knee flexion and extension (60°/s) at RTS, and three and six months later. Twenty controls were tested once. T-tests were used to compare strength differences between 1) ACLR athletes and controls and 2) the injured and uninjured leg of the ACLR athletes. Finally, to assess strength deficits over time, two-way ANOVAs were used.

RESULTS

Angle-specific analyses and peak moments showed lower hamstrings strength in the injured leg of ACLR athletes compared to their uninjured leg at RTS. Furthermore, angle-specific analyses showed a lower hamstrings strength and H/Q ratio in the injured leg compared to controls at larger knee flexion angles. The latter deficit was not identified with a peak-based analysis. The asymmetries identified at RTS did not change over the six months following RTS.

CONCLUSIONS

Athletes with ACLR show strength deficits and asymmetries that persist even six months after RTS. As some asymmetries may go undetected by peak-based analyses, angle-specific analyses are recommended.

LEVEL OF EVIDENCE

Level 3b.

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.

Quadriceps-Strength-Testing Practices and Barriers During Return to Sport After ACL Reconstruction: A Survey of College Athletic Trainers

CONTEXT

Quadriceps strength is a key outcome for guiding rehabilitation and return to sport-specific activities after anterior cruciate ligament reconstruction (ACLR) surgery.

OBJECTIVE

(1) Describe the quadriceps-strength-testing practices and barriers college athletic trainers (ATs) are using and experiencing when returning patients to sport-specific activities after ACLR. (2) Compare testing methods between college ATs working in the National Collegiate Athletic Association (NCAA) Division I setting and other college settings.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENTS OR OTHER PARTICIPANTS

Two hundred forty-three full-time collegiate ATs who had primarily overseen/directed an ACLR rehabilitation in the past 5 years (age = 34.8 ± 10.7 years, length of AT practice = 11.7 ± 9.3 years, NCAA Division I setting = 56%).

MAIN OUTCOME MEASURE(S)

Our survey included 4 sections: demographics, general ACLR rehabilitation practices, quadriceps-strength-testing methods and criteria, and quadriceps-strength-testing barriers.

RESULTS

Knee-muscle strength was the most common (98%) outcome collegiate ATs used when determining whether an ACLR patient is ready to progress to sport-specific activities. Manual muscle testing was the most used testing method (57%), followed by isokinetic dynamometry (IKD) (48%), repetition maximum testing (35%) and handheld dynamometry (22%). Most ATs (63%-64%) used greater than 90% side-to-side symmetry as their return to sport-specific activities criterion. Lack of equipment needed (83%), lack of financial means (28%), and lack of training/education (20%) were the barriers that most limited ATs use of IKD testing, the gold standard testing method. Compared with ATs in other settings, a greater proportion of ATs working in the NCAA Division I setting used IKD testing (65% vs 28%) and a smaller proportion used manual muscle testing (47% vs 70%).

CONCLUSIONS

Although almost all college ATs considered knee-muscle strength an important outcome to assess when returning patients to sport-specific activities after ACLR, quadriceps-strength-testing practices were highly variable among ATs and may be affected by access to necessary resources.

Strength Setbacks: The Impact of Youth Sport-Related Knee Joint Injuries on Thigh Muscle Strength. A 24-Month Prospective Cohort Study

OBJECTIVE: To compare injured and uninjured limb knee extensor and flexor peak torque between youth who experienced a sport-related, traumatic knee joint injury and comparable uninjured youth, at baseline (≤4 months of injury) and semiannually for 2 years. Differences by injury type and sex were also explored. DESIGN: Prospective cohort study. METHODS: Bilateral knee extensor and flexor concentric isokinetic peak torque at 90° per second was assessed semiannually in 186 youth (106 injured, 80 controls) for 2 years. Between-group differences in strength over time were estimated with generalized estimating equations (95% confidence interval [CI]). Confounding was controlled using inverse probability weighting. Strength differences between those with anterior cruciate ligament (ACL) tears and those with non-ACL tear injuries as well as between male and female participants were explored. RESULTS: Compared to uninjured controls, injured limb knee extensor strength was lowest at baseline (-37.1 Nm; 95% CI, -45.3 to -28.9) and 6-month follow-up (-13.3 Nm; 95% CI, -20.4 to -6.2), with minimal strength gain beyond the 12-month follow-up (1.7 Nm; 95% CI, -14.3 to 17.6). Knee flexor strength of the injured limb was lowest at baseline (-24.6 Nm; 95% CI, -31.5 to -17.8), and there was minimal strength gain beyond 6 months (2.3 Nm; 95% CI, -7.7 to 12.3). The average residual deficit was similar to the knee extensors (10% to 11%) at 24 months. Exploratory analysis suggested no difference based on injury type or sex. CONCLUSION: Injured limb knee extensor and flexor weakness was present after different youth sport-related knee joint injuries. Strength deficits peaked early after injury, improved over time, and plateaued after 12 months, with lingering deficits at 24 months. Thigh muscle strength trajectory was similar across injury types and sex. J Orthop Sports Phys Ther 2025;55(2):1-11. Epub 20 December 2024. doi:10.2519/jospt.2024.12663.

Primary Anterior Cruciate Ligament Reconstruction Performed With Hamstring Tendon Autograft Leads to an Over 4 Times Greater Rate of Second Anterior Cruciate Ligament Rupture After Return to Sport in Patients With Generalized Joint Hypermobility Compared With Bone-Patellar Tendon-Bone Autograft

PURPOSE

To examine the rate of (1) second anterior cruciate ligament (ACL) rupture (graft rupture or contralateral ACL rupture) and (2) graft rupture alone in patients with generalized joint hypermobility (GJH) at 12 months, at 24 months, and at the longest available time (LAT) following return to sport (RTS) after ACL reconstruction depending on graft choice, that is, hamstring tendon (HT) autograft or bone-patellar tendon-bone (BPTB) autograft.

METHODS

Data were extracted from a rehabilitation registry that comprised patients who had undergone ACL reconstruction between 2014 and 2022. Patients with GJH aged between 16 and 50 years who had minimum 24-month follow-up following RTS after ACL reconstruction with HT autograft (GJH-HT) or BPTB autograft (GJH-BPTB) were included. A Cox proportional hazard regression model was used to examine the rate of (1) second ACL rupture (graft rupture or contralateral ACL rupture) and (2) graft rupture alone at 12 months, at 24 months, and at the LAT after RTS.

RESULTS

This study included 82 patients (54 in the GJH-HT group and 28 in the GJH-BPTB group), of whom 72.0% were female patients, and the average age was 22.7 ± 7.4 years. The proportion of second ACL ruptures was greater in the GJH-HT group than in the GJH-BPTB group at 12 months (11 of 54 [20.4%] vs 0 of 28 [0%], P = .013), at 24 months (13 of 54 [24.1%] vs 1 of 28 [3.6%], P = .028), and at the LAT (16 of 54 [29.6%] vs 2 of 28 [7.1%], P = .024) after RTS. The rate of second ACL rupture was greater in the GJH-HT group than in the GJH-BPTB (hazard ratio = 4.98, P = .032) at the LAT after RTS. The proportion of patients with graft rupture was greater in the GJH-HT group than in the GJH-BPTB group at 12 months (8 of 54 [14.8%] vs 0 of 28 [0%], P = .046), at 24 months (10 of 54 [18.5%] vs 0 of 28 [0%], P = .013), and at the LAT (12 of 54 [22.2%] vs 0 of 28 [0%], P = .006) after RTS.

CONCLUSIONS

An over 4 times greater rate of second ACL rupture after RTS was reported for patients with GJH who underwent ACL reconstruction with HT autograft compared with BPTB autograft. Patients with GJH who were treated with BPTB autograft for ACL reconstruction did not experience graft rupture after RTS.

LEVEL OF EVIDENCE

Level III, retrospective study.

A comparative analysis of autograft choices of anterior cruciate ligament reconstruction and their effects on muscle strength and joint biomechanics

Introduction

Anterior cruciate ligament reconstruction (ACLR) is crucial to restore knee stability and function after ACL injuries, especially in physically active individuals. Despite advances in surgical techniques and rehabilitation protocols, the choice of autograft has a significant impact on postoperative recovery, particularly on muscle strength and joint biomechanics. In this study, the effects of four autografts are investigated: Iliotibial band (ITB), combined ITB and hamstring tendon (ITB + HT), hamstring tendon (HT) and bone-tendon-bone (BTB) on quadriceps and hamstring peak torque (QPT and HPT) recovery and hamstring to quadriceps ratio (H:Q) to assess knee stability and function.

Methods

Forty-two active males (mean ± standard deviation of age: 31.5 ± 6.1 years, height: 177 ± 6 cm, weight: 76 ± 11 kg, body mass index: 24.5 ± 2.2 kg/m²) with primary ACL ruptures were allocated to the four graft groups (ITB: n = 16, ITB + HT: n = 12, HT: n = 7, BTB: n = 7) and underwent a standardized rehabilitation protocol. Quadriceps and hamstring peak torque (QPT and HPT, respectively) as indicators of isokinetic muscle strength were assessed both postoperatively and follow-up after approximately six months (mean 6.29 ± 1.70 months).

Results

Significant differences in QPT and HPT recovery between the healthy and injured legs were found in all graft groups (P < 0.001). The BTB group showed the largest QPT deficit between healthy and injured legs (Δ = 133.4 Nm, Cohen's d = 8.05) and HPT deficit (Δ = 41.1 Nm, Cohen's d = 4.01). In contrast, the ITB + HT group showed the smallest deficits in QPT (Δ = 22.5 Nm, Cohen's d = 0.73) and HPT (Δ = 13.5 Nm, Cohen's d = 1.21). The BTB group also showed the largest deviation in H:Q ratios (Δ = -0.23, Cohen's d = 2.70), while the HT group showed a more balanced recovery with smaller significant deficits in H:Q ratios (Δ = -0.07, Cohen's d = 0.46).

Conclusion

The BTB graft showed the most pronounced variations in QPT and HPT between healthy and injured legs in the short term, indicating the importance of longitudinally monitoring knee stability to determine the best autograft choice for ACLR. While all graft types contribute to muscle strength recovery, the HT graft may provide advantages in balancing muscle strength and potentially enhancing knee stability.

Return to competition after ACL reconstruction: Factors influencing rates and timing in Swedish football players

PURPOSE

To investigate the rate and timing for return to football league games after anterior cruciate ligament reconstruction (ACLR) in Swedish players, examining associations with sex, age, level, graft and additional ACL surgery.

METHOD

Data from the Swedish National Knee Registry (SNKLR) and the Swedish Football Association's IT System (FOGIS) were used. The study cohort comprised 971 football players, 64% males, who underwent primary ACLR. Demographics, graft type and surgical information were extracted from the SNKLR and game participation from FOGIS. Follow-up for return to competition (RTC) was conducted for 36 months, while additional ACLR follow-up was 3-7 years. Statistical analyses, including Kaplan-Meier survival curves and relative risk calculations, were employed to assess factors influencing RTC rates and timing.

RESULTS

Out of 971 players analyzed, 53% RTC within 3 years with no difference between males and females, at a mean of 15 months (median 14 months) from surgery to the first game. Eleven (2%) players RTC < 6 months from ACLR, 62 (12%) 6-9 months, 125 (24%) 9-12 months and 331 (63%) >12 months. Patellar tendon (PT) grafts demonstrated superior performance, showing quicker returns and higher RTC rates (p = 0.005) compared to hamstring (hazard ratio [HR]: 0.63 [0.48-0.84]) and quadriceps tendon grafts (HR: 0.53 [0.30-0.93]). Players competing in higher divisions pre-injury experienced significantly swifter and higher RTC rates (p < 0.001). Ninety-five (10%) had a registered additional ACLR. Players who RTC did not exhibit a significantly higher rate of revision (35 [7%] vs. 25 [5%]). However, those who returned faced a heightened risk of contralateral ACLRs compared to those who did not RTC (32 [6%] vs. 4 [1%] RR 1.72 [1.59-1.96], p < 0.001).

CONCLUSION

The study reveals that 53% of football players RTC after ACLR, predominantly after more than 12 months. The RTC was higher and faster in high-level players and those receiving a PT graft. The slow RTC may contribute to the relatively low rate of additional ACLRs.

LEVEL OF EVIDENCE

Level III.

Use of extracorporeal shockwave therapy combined with standard rehabilitation following anterior cruciate ligament reconstruction: a systematic review with meta-analysis

BACKGROUND

Anterior cruciate ligament (ACL) injuries are one of the most common sports injuries, accounting for approximately 50% of knee-related injuries. Extracorporeal shockwave therapy (ESWT), in the form of the radial (R-SWT) or focused shockwave (F-SWT), has been shown effective in treating various orthopaedic conditions. Recently, studies have investigated whether ESWT combined with standard rehabilitation may improve outcomes following anterior cruciate ligament reconstruction (ACLR). Therefore, this study aimed to determine whether ESWT can improve clinical outcomes following ACLR.

METHODS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We searched PubMed, Embase, and Web of Science and included studies involving ESWT treatment following ACLR, which consisted of randomized controlled trials (RCTs) and cohort studies. Two authors independently extracted the outcome measurements and used a revised Cochrane risk-of-bias tool (RoB 2) for RCTs and the Risk of Bias in Non-randomised Studies of Interventions (ROBINS-I) for a cohort study to assess the risk of bias. A random effects pairwise meta-analysis was used to compare patient-reported outcomes between ESWT and controlled treatments.

RESULTS

Five studies (Level I: 4; Level II: 1) with 242 participants (male: 167; female: 75) were included. Regarding the patient-reported outcomes, the risk of bias for all RCTs was 'high' and 'serious' for a non-randomized study. The meta-analysis demonstrated that the Lysholm scores were significantly higher in ESWT groups than those of controls at 12 months (Weighted mean difference [WMD]: 7.037, 95% confidence interval [CI]: 6.172-7.902, I2: 0%) and 24 months (WMD: 5.463, 95% CI: 2.870-8.056, I2: 0%). Furthermore, the International Knee Documentation Committee (IKDC) scores were also significantly higher in the ESWT group than that of the control at 12 months (WMD: 6.371, 95% CI: 3.397-9.344, I2: 68.8%). However, the WMDs for these outcomes between the two groups did not exceed the minimal clinically important difference (MCID).

CONCLUSION

Based on the meta-analyses performed with a few studies, ESWT combined with standard rehabilitation may potentially lead to better patient-reported outcomes. However, these differences may not be clinically significant. Further high-quality studies are needed to confirm our review's findings.

Impact of Functional Training on Injuries After Anterior Cruciate Ligament Reconstruction for Return-to-Duty Status in U.S. Naval Academy Midshipmen: A Retrospective Analysis

INTRODUCTION

Acute anterior cruciate ligament (ACL) injuries can be disabling because of prolonged rehabilitation process following surgical reconstructions. Rates of ACL injuries among military service members are close to 10 times greater than the general civilian population, likely because of the operation tempo and the unique physical requirements. Studies debated functional testing requirements for return to sports, but no study investigated the impact of functional training and re-injury rates following ACL reconstruction and their association with functional testing outcomes and time to return to full duty in United States Naval Academy (USNA) Midshipmen. Therefore, the purpose of this study was to review all ACL reconstructions with and without meniscal injury at USNA, the functional training and testing, timing of return to military training, and associations with postoperative re-injury rates.

MATERIALS AND METHODS

A retrospective chart review of all Midshipmen who sustained ACL reconstructions between 2015 and 2019 was performed. Demographic variables, type of surgeries, functional training/testing outcomes, timing to return to full duty and postoperative re-injury rates were recorded up to January 1, 2022.

RESULTS

Of 204 ACL reconstructions, 87 were excluded, resulting in a sample size of 117 including 76 (65%) men and 41 (35%) women aged 20.4 ± 1.4 years. Fifty-one (44%) Midshipmen sustained a re-injury to the postoperative knee or complication. Thirty-three out of 76 (43%) men and 18 out of 41 (35%) women sustained complication or re-injury to the surgical knee. Of those re-injuries or complications, 12 Midshipmen (10%) sustained graft failures,12 (10%) anterior arthrofibrosis, 7 (6%) meniscus tears, 17 (15%) patella tendinopathy, and 3% other ligament injuries (MCL, PCL, etc.). Fifty participants (43%) followed a functional training program while 67 (57%) lacked documented functional training. There was a significant difference in Midshipmen who participated in functional training, displaying fewer postoperative anterior cruciate ligament reconstruction (ACLR) re-injuries or complications to the surgical knee as compared to those who did not (0.027). Nineteen Midshipmen (16%) performed functional testing while 98 did not. Of the 98 Midshipmen who did not perform functional testing, 57 (58%) had re-injury or complications to the surgical knee postoperatively compared to 9 (48%) who performed functional testing sustained a re-injury or complication. The average return to full duty was 37.1 ± 25.8 weeks versus 63.8 ± 35.8 weeks for Midshipmen who sustained postoperative injuries. Within 1 year of return to duty, 6 of 12 (50%) ACL graft failures occurred.

DISCUSSION-CONCLUSION

Postoperative injuries and complications following ACLR can delay the ability to return to duty by twice as long, consequently effecting military manpower capability. A functional training and testing program resembling both an athletic and military/operational environment can reduce re-injury and complication rates, resulting in faster return-to-duty rates. Future studies should assess the impact of military rehabilitation participation following ACLR and functional testing protocols to assess physical readiness of Midshipmen to return to full duty. Additionally, methods to assess psychological readiness to return to duty should be further investigated.

Antioxidant taurine inhibits chondrocyte ferroptosis through upregulation of OGT/Gpx4 signaling in osteoarthritis induced by anterior cruciate ligament transection

OBJECTIVE

The aim of this study was to investigate the potential molecular mechanisms by which taurine protects against cartilage degeneration.

METHODS

The anterior cruciate ligament transection (ACLT) surgery was used to construct an animal model of osteoarthritis (OA). Metabolomics was used to identify characteristic metabolites in osteoarthritic chondrocytes. Transcriptomics and metabolomics were used to explore potential mechanisms by which the small molecule metabolite taurine protects against inflammatory chondrocyte damage. Cell transfection and small molecule inhibitors/agonists were used to validate the molecular mechanisms by which taurine protects inflammatory chondrocytes in vitro. Finally, adeno-associated virus and small molecule inhibitors/agonists were used to validate the molecular mechanisms by which taurine protects against cartilage degeneration in vivo.

RESULTS

Metabolomic assays identified taurine as a possible key metabolic molecule in the progression of OA. Transcriptomics and metabolomics revealed that O-GlcNAc transferase (OGT)-dependent O-GlcNAcylation and Gpx4-dependent ferroptosis may mediate the inflammatory protective effects of taurine on chondrocytes, which was further confirmed by gain and loss of function in vitro. Subsequently, further experiments indicated that the possible existence of a direct binding site for Gpx4 and OGT proteins, which provides evidence for the presence of O-GlcNAc modification of Gpx4 protein. Finnaly, we demonstrated that Gpx4-dependent ferroptosis and OGT-dependent O-GlcNAcylation may be potential mechanisms by which taurine protects against cartilage degeneration in vivo.

CONCLUSION

Antioxidant taurine inhibits chondrocyte ferroptosis through upregulation of OGT/Gpx4 signaling. Supplementation with taurine, a safe nonessential amino acid, may be a potential therapeutic strategy for OA.

Augmented Feedback Response Prediction by Peak Vertical Ground Reaction Force in Adolescent Female Athletes

Background and Purpose

Anterior cruciate ligament (ACL) tears often occur due to non-contact mechanisms in landing within females. Impact loading and aberrant landings may be addressed with augmented feedback training. The purpose of this study was to identify which female athletes most readily respond to a single session of augmented feedback to attenuate vGRF, by considering baseline peak vGFR and change in vGRF during training.

Design

Repeated Measures.

Methods

One hundred, forty-seven female athletes landed from 50 cm onto two force platforms with and without augmented feedback of vertical ground reaction force (vGRF), vGRF symmetry, and lower extremity position. Each performed six baseline trials and two sets of six training trials with cues. Following training, athletes completed six post-feedback trials (with no feedback) and six dual-task (transfer) trials where they randomly caught a basketball during landing. Peak vGRF was measured. Mean responses were reported for the sets of six trials. Participants were grouped based on their responses to training. Linear regression was used to indicate how well initial performance and response predicted the final response.

Results

Four groups were identified, with 107 participants showing high baseline ground reaction forces and response to training. Only 23 participants (16.4%) did not respond to training. Baseline vGRF predicted post-feedback vGRF and transfer task vGRF (R2=0.508 and R2=0.400) across all participants. When change in vGRF was assessed following two blocks of augmented feedback training, prediction of responders improved with post-feedback vGRF and transfer vGRF (R2=0.911 and R2=0.761).

Conclusions

The combination of both baseline ground reaction force and response to initial training is more accurate than baseline measures alone in identifying those who respond to training. Assessing initial response to training may be necessary to more accurately identify individuals most likely to benefit from augmented feedback training and who may require further evaluation and training.

Level of Evidence

2b.

Leg stiffness during running in adults with traumatic brain injury: A comparative study with healthy adults

BACKGROUND

While leg stiffness during running has been shown to be lower in children with cerebral palsy compared to their typically developing peers, no studies have examined leg stiffness during running in adults with traumatic brain injury. The aim of this study was to compare leg stiffness during running in adults with traumatic brain injury to healthy controls.

METHODS

Sixty-one adults with traumatic brain injury and 20 healthy controls were included. Participants ran overground while three-dimensional kinematic and kinetic data were recorded. Leg stiffness was calculated during the stance phase of running. Statistical analyses to compare leg stiffness between limbs and between groups were conducted using t-tests.

FINDINGS

There was a large range of leg stiffness in adults with traumatic brain injury during running (affected leg median = 21.56 [range 11.07 to 57.44] kN/m; less affected leg =20.87 [9.38 to 54.72] kN/m) compared to healthy controls (20.94 [13.40 to 31.50] kN/m). However, there were no statistically significant differences in leg stiffness during running between the affected and less affected limbs (p = 0.59, effect size [ES] =0.08) nor between both traumatic brain injury limbs and healthy controls (affected limb; p = 0.44, ES =0.12; less affected limb; p = 0.47, ES =0.11).

INTERPRETATION

Although no statistical significance was found on a group level, the results demonstrated high variability in leg stiffness in traumatic brain injury compared to healthy controls. Further research is needed to determine which factors influence leg stiffness during running and how this measure relates to clinical outcomes in traumatic brain injury.

Quantifying performance and joint kinematics in functional tasks crucial for anterior cruciate ligament rehabilitation using smartphone video and pose detection

BACKGROUND

The assessment of performance during functional tasks and the quality of movement execution are crucial metrics in the rehabilitation of patients with anterior cruciate ligament (ACL) injuries. While measuring performance is feasible in clinical practice, quantifying joint kinematics poses greater challenges. The aim of this study was to investigate whether smartphone video, using deep neural networks for human pose detection, can enable the clinicians not only to measure performance in functional tasks but also to assess joint kinematics.

METHODS

Twelve healthy participants performed the forward reach of the Star Excursion Balance Test 10 times, along with 10 repetitions of forward jumps and vertical jumps, with simultaneous motion capture via a marker-based reference system and a smartphone. OpenPifPaf was utilized for markerless detection of anatomical landmarks in video recordings. The OpenPifPaf coordinates were scaled using anthropometric data of the thigh, and task performance and joint kinematics were computed for both the marker-based and markerless systems.

RESULTS

Comparing results for marker-based and markerless systems revealed similar joint angles, with mean root mean square errors of 2.8° for the knee, 3.1° for the hip, and 3.9° for the ankle. Excellent agreement was observed for clinically pertinent parameters, i.e., the performance, the peak knee flexion, and the knee range of motion (intraclass correlation coefficient > 0.97).

CONCLUSION

The results underscore the feasibility of using markerless methods based on OpenPifPaf for assessing performance and joint kinematics in functional tasks crucial for ACL patients' rehabilitation. The simplicity of this approach makes it suitable for integration into clinical practice.

The influence of menstrual cycle phase on isokinetic knee flexor and extensor strength in female soccer players: a pilot study

The prevalence of anterior cruciate ligament injury in female soccer players has been attributed to hormonal fluctuations during the menstrual cycle (MC), with injury incidence greatest during the follicular phase. Eight, eumenorrheic, collegiate soccer players (19.5 ± 0.75 years, 1.62 ± 4.90 cm, 61.12 ± 7.6 kg mean ± SD) completed eccentric knee flexor and concentric knee extensor trials at 60 and 240°·s-1 during the follicular, ovulation and luteal phases of their MC. Peak torque and corresponding angle of peak torque were maintained across all phases of the MC, irrespective of testing modality and speed (p ≥ 0.149). Strength ratios defined using peak torque were also not sensitive to MC phase (p ≥ 0.933). However, Functional Range in eccentric knee flexion was significantly lower during the follicular phase (p = 0.017), at both testing speeds. This supports epidemiological observations but highlights the importance of analysing isokinetic data beyond the peak of the strength curve. Interpretation of isokinetic data should therefore focus on points of "weakness" as opposed to maximum strength, whilst (p)rehabilitative strategies should consider strength through range of motion, and at different speeds. Eccentric hamstring strength was observed to decrease significantly at the higher speed, contrary to observations in elite male players, and potentially reflecting a differential training adaptation.

Rehabilitation and Return to Play Protocols After Anterior Cruciate Ligament Reconstruction in Soccer Players: A Systematic Review

BACKGROUND

Rehabilitation after anterior cruciate ligament ACL reconstruction (ACLR) is crucial for safe return to play (RTP) and reducing the chances of a reinjury. Yet, there is no consensus on the ideal functional tests to assess rehabilitation progress in soccer players after ACLR.

PURPOSE

The primary objective was to highlight the existing gap in the literature concerning the most effective standardized rehabilitation protocols and testing for facilitating successful RTP among soccer players.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review using PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) was conducted. Inclusion criteria encompassed original studies (level of evidence 1-4) that examined rehabilitation protocols, metrics of knee rehabilitation, and clinical outcomes after ACLR in soccer players.

RESULTS

This review incorporated 23 studies, predominantly retrospective case series, with a total number of 874 soccer players who underwent ACLR and rehabiliation. 5 (21.7%) studies utilized an accelerated rehabilitation protocol, while 7 (30.4%) of studies utilized a criterion-based rehabilitation. A wide heterogeneity of data was extracted including functional tests of rehabilitation and RTP such as strength test batteries, hop test batteries, and movement quality assessments. Of the 23 selected studies, 2 (8.7%) used all 3 test batteries, 8 (34.8%) used 2 test batteries, 12 (52.2%) used 1 test battery, and 1 (4.3%) used 0 of the test batteries. The mean time between surgery and RTP ranged from 3 to 8 months with only 2 (8.7%) studies reporting complications after ACLR. Lastly, out of the total studies examined, 9 (39.1%) assessed patient-reported outcome measures (PROMs), all of which demonstrated significant improvement from the initial assessment to the final follow up.

CONCLUSION

Soccer-specific rehabilitation after ACLR lacks standardization. Even though many studies have assessed protocols for optimal RTP and reduced secondary ACL injuries, there is a gap in the literature regarding the most effective protocols and RTP testing. The methodology reported by Kyritsis et al could serve as a foundation for future prospective randomized multicenter studies to establish a standard rehabilitation protocol and enable a successful return to soccer.

Sex-based differences in physical and psychological recovery, and return to sport, following anterior cruciate ligament reconstruction

BACKGROUND

A robust comparison of the recovery pathway between sexes after anterior cruciate ligament reconstruction (ACLR) is lacking. This study investigated sex-based differences in physical and psychological recovery, and return to sport (RTS), after ACLR.

METHODS

104 community-level patients underwent ACLR. Patients were evaluated at 6-, 12- and 24-months with the Anterior Cruciate Ligament Return to Sport after Injury Scale (ACL-RSI), International Knee Documentation Committee (IKDC) form and Tegner Activity Scale (TAS), a 4-hop test battery including the 6-meter timed hop (6MTH) and the single (SHD), triple (THD) and triple crossover (TCHD) hop tests for distance, and peak isokinetic knee extensor and flexor torque. Sex-based differences were assessed, while regression analysis modelled the relationship between patient characteristics and outcomes, with 24-month psychological readiness to RTS.

RESULTS

All PROMS improved (p < 0.05), with males reporting higher 24-month ACL-RSI (p = 0.002), IKDC (p = 0.007) and TAS (p = 0.005) scores. A greater percentage of males returned to pivoting sports at 24 months (p = 0.030, males 60.0%, females 40.8%). Males demonstrated higher knee extensor strength LSIs at 6 (p = 0.037) and 24 (p = 0.047) months, and higher knee flexor strength LSIs at 6 (p = 0.007) and 12 (p = 0.002) months. IKDC knee scores (β = 24.9; 95% CI, 10.8 to 35.0), male sex (β = 12.2; 95% CI, 3.9 to 20.4) and the 6MTH LSI (β = 1.31; 95% CI, 0.6 to 2.1) were associated with the ACL-RSI.

CONCLUSIONS

In community-level ACLR patients, females demonstrated lower physical performance recovery, subjective function and psychological readiness, as well as a lower rate of RTS.

Rehabilitation and assessment practices following anterior cruciate ligament injury: A survey of Australian physiotherapists

OBJECTIVE

This study aimed to investigate the current beliefs and practices among Australian physiotherapists regarding the management of anterior cruciate ligament (ACL) injuries.

DESIGN

Cross-sectional survey.

SETTING

Online survey.

PARTICIPANTS

Australian physiotherapists.

OUTCOME MEASURES

The survey assessed beliefs and practices regarding non-operative management, ACL reconstruction, pre- and post-operative rehabilitation, and return to sport (RTS) criteria. Frequencies and percentages summarized survey responses, and chi-square or Fisher's exact tests assessed whether beliefs and practices were influenced by experience (≤6 years or >6 years) and annual caseload (<6 or ≥6 patients).

RESULTS

In total, 419 physiotherapists were included, with 367 completing the survey in its entirety. Most physiotherapists (86.8%) consider non-surgical management alternatives for patients. Two-thirds (59.8%) recommend a minimum of 9-12 months before RTS, emphasizing recovery of knee strength (93.9%) and psychological readiness (93.9%). Of those who assessed strength, 32.5% use manual muscle testing, and 37.4% assess strength from hop testing. The 63.5% of respondents who reported barriers to implementing best practice ACL management, cited lack of resources (69.1%) and patient non-compliance (67.8%) as the most common reasons.

CONCLUSION

This survey of Australian physiotherapists showed alignment with evidence-based ACL guidelines but highlighted differences from international practices and variations by experience and caseload.

Evaluation of Thigh Muscle Strength in Adolescent Patients After Anterior Cruciate Ligament Reconstruction With Lateral Extra-articular Tenodesis or Anterolateral Ligament Reconstruction

Background

There has been increased interest in lateral extra-articular procedures, such as anterolateral ligament reconstruction (ALLR) or lateral extra-articular tenodesis (LET), to reduce anterolateral rotation instability of the knee after anterior cruciate ligament reconstruction (ACLR). Despite promising surgical outcomes with these techniques, their impact on knee strength recovery is unknown.

Hypothesis

Patients undergoing lateral extra-articular procedures at the time of ACLR would have impaired thigh muscle strength at 6 to 9 months after surgery.

Study Design

Cohort study; Level of evidence, 3.

Methods

Adolescent patients who had undergone primary unilateral ACLR with lateral extra-articular augmentation between 2017 and 2023 were identified. Patients were included if they were aged between 12 and 20 years at the time of surgery and had completed an isokinetic strength assessment at 6 to 9 months after surgery. A total of 104 participants (mean age, 16.5 ± 1.7 years; 63 female) were included in this analysis: 25 who underwent ACLR+ALLR, 17 who underwent ACLR+LET, and 62 who underwent isolated ACLR. Isokinetic knee extension and flexion strength normalized to body weight, as well as the bilateral limb symmetry index (LSI), were assessed. One-way analysis of variance and analysis of covariance were used to compare differences between surgical techniques.

Results

After adjusting for age, graft type, and time since surgery, the ACLR+LET (1.36 ± 0.52 N·m/kg) and ACLR+ALLR (1.61 ± 0.53 N·m/kg) groups had significantly less involved limb knee extension strength (P = .025), uninvolved limb knee extension strength (P = .046), and LSI for knee extension strength (P = .040) compared to the isolated ACLR group. There were no differences between the 3 groups regarding involved limb knee flexion strength (P = .222) or uninvolved limb knee flexion strength (P = .984), but the isolated ACLR group displayed a greater LSI for knee flexion strength (96.6% ± 17.8%; P = .012).

Conclusion

The addition of lateral extra-articular procedures at the time of ACLR was associated with decreased quadriceps strength at 6 to 9 months after ACLR. While lateral extra-articular procedures may enhance knee rotary stability after ACLR, prolonged rehabilitation may be needed to re-establish adequate quadriceps strength before return to sports.

Poor knee strength is associated with higher incidence of knee injury in adolescent female football players: The Karolinska football injury cohort

PURPOSE

To investigate the association between common measures of trunk and lower extremity range of motion (ROM), strength, the results of one-leg jump tests at baseline and the incidence of subsequent substantial knee injuries in adolescent female football players.

METHODS

Players were assessed at baseline regarding (1) ROM of trunk, hip, and ankle; (2) trunk, hip, and knee strength; and (3) one-leg jump tests. Players were prospectively monitored weekly for 1 year regarding knee injuries and the volume of matches and training. Hazard rate ratios (HRRs) and 95% confidence intervals (CIs) were calculated with Cox regression for the association between the baseline tests and the incidence of substantial knee injury (moderate/severe reduction in training volume or performance, or complete inability to participate in football). Exposures were categorized in tertiles (high, medium and low values). The highest tertile was used as reference.

RESULTS

376 players were included without substantial knee injury at baseline (mean age, 13.9 ± 1.1 years), and 71 (19%) reported at least one substantial knee injury during the follow-up. Several associations were found; the strongest was that players in the lowest tertile of knee extension strength had a higher incidence of knee injuries than players in the highest tertile (HRR, 2.28; 95% CI, 1.20-4.38). Players in the lowest tertile of trunk rotation ROM in lunge position half-kneeling (HRR, 0.50; 95% CI, 0.27-0.94) had lower incidence of knee injuries than players in the highest tertile.

CONCLUSIONS

Poor knee strength and high trunk ROM were associated with an increased incidence of substantial knee injury in adolescent female football players. Therefore, knee-strengthening exercises during season may be recommended.

LEVEL OF EVIDENCE

Level II.

Finding the needle in the haystack of isokinetic knee data: Random Forest modelling improves information about ACLR-related deficiencies

The difficulties of rehabilitation after anterior cruciate ligament (ACL) injuries, subsequent return-to-sport (RTS) let alone achieving pre-injury performance, are well known. Isokinetic testing is often used to assess strength capacities during that process. The aim of the present machine learning (ML) approach was to examine which isokinetic data differentiates athletes post ACL reconstruction (ACLR) and healthy controls. Two Random Forest models were trained from data of unilateral concentric and eccentric knee flexor and extensor tests (30°/s, 150°/s) of 366 male (63 post ACLR) as well as 183 female (72 post ACLR) athletes. Via a cross-validation predictive performance was evaluated and the Random Forest showed outstanding results for male (AUC = 0.90, sensitivity = 0.76, specificity = 0.88) and female (AUC = 0.92, sensitivity = 0.85, specificity = 0.89) athletes. The Accumulated Local Effects plot was used to determine the impact of single features on the predictive likelihood. For both male and female athletes, the ten most impactful features either referred to the disadvantageous (injured, non-dominant in control group) leg or to lateral differences. The eccentric hamstring work at 150°/s was identified as the most impactful single parameter. We see potential for improving the RTS process by incorporating and combining measures, which focus on hamstring strength, leg symmetry and contractional work.