Muscle strength and hop performance criteria prior to return to sports after ACL reconstruction

Revision ACL reconstruction, but not bilateral ACL reconstruction, is associated with clinically relevant inferior subjective knee function compared with primary ACL reconstruction: A comparative analysis of 6831 patients

PURPOSE

To evaluate and compare the subjective knee function in patients undergoing revision and bilateral anterior cruciate ligament (ACL) reconstruction (ACLR) with those undergoing primary ACLR in a large cohort.

METHODS

Patients without concomitant ligament injuries who underwent primary, revision or bilateral ACLR at the Capio Artro Clinic, Stockholm, Sweden, between 2005 and 2018 were identified. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at 1, 2 and 5 years postoperatively from the Swedish National Knee Ligament Registry. Patients who underwent revision and bilateral ACLR were compared with those who underwent primary ACLR (control group) using Student's t test.

RESULTS

A total of 6831 patients (6102 with primary ACLRs, 343 with revision ACLRs and 386 with bilateral ACLRs) were included. Preoperatively, there were significant but nonclinically relevant differences in favour of the revision ACLR group for KOOS Symptoms, Pain, Activities of Daily Living (ADL) and Sport/Rec subscale scores compared with the primary ACLR group. Postoperatively, except for the 1-year Symptoms and ADL subscales, the revision ACLR group reported significantly lower scores on all KOOS subscales than the primary ACLR group, with clinically relevant differences (>8-10 points) for the 1-, 2- and 5-year Sport/Rec and Quality of Life (QOL) subscales. The bilateral ACLR group reported significantly, but not clinically relevant, inferior scores on the 1-year Symptoms and QOL subscales and the 5-year Sport/Rec and QOL subscales compared with the primary ACLR group.

CONCLUSIONS

Revision ACLR, but not bilateral ACLR, was associated with clinically relevant inferior subjective knee function compared with primary ACLR. It is important to counsel patients regarding their future subjective knee function after repeated ACLR. Compared to primary ACLR, inferior subjective results should be expected after revision ACLR, but not after bilateral ACLR.

LEVEL OF EVIDENCE

Level III.

Retrospective Study on the Efficacy of Platelet-Rich Plasma Treatment in the Recovery of Quadriceps Muscle Strength After Anterior Cruciate Ligament Reconstruction in Non-Professional Athletes

Background/Objectives: This retrospective study aimed to evaluate whether PRP infiltrations improve quadriceps muscle strength recovery following anterior cruciate ligament reconstruction (ACLR), while minimizing the recovery time required to resume daily activities and sports. Numerous studies have explored the use of platelet-rich plasma (PRP) in treating ACL injuries. PRP therapy has demonstrated high efficacy in accelerating ligament healing in animal models. However, clinical trials involving human participants have reported inconsistent results regarding the effects of PRP on ACL reconstruction outcomes. Methods: Between 2020 and 2024, a total of 68 subjects who underwent ACLR were included in the study. Participants were divided into two groups, namely a treatment group that followed a standard rehabilitation protocol and received PRP infiltrations, and a control group that followed the same protocol without PRP treatment. Muscle strength was assessed using the isometric max strength balance (IMSB) test and the concentric max strength balance (CMSB) test, both performed using the Kineo Intelligent Load device (Globus Kineo 7000, Italian Excellence, Rome, Italy). Results: The results of IMSB test showed a significant difference between treatment groups according to a two-way ANOVA test (F(1, 198) = 7.345; p = 0.0073). The PRP-treated group showed significantly higher quadriceps muscle strength at 6 months (34.9 ± 9.6 vs. 30.0 ± 8.2 kg). The CMSB test also showed a significant difference at 6 months (F(1, 198) = 5.976; p = 0.00154), with the PRP-treated group having significantly higher concentric muscle strength (35.5 ± 9.5 vs. 30.7 ± 8.5 kg). Conclusions: These findings suggest that post-ligamentoplasty PRP infiltrations may have beneficial effects on muscle strength recovery. However, further prospective studies with larger sample sizes are necessary to confirm these results.

Cortical activity during the first 4 months after anterior cruciate ligament reconstruction while performing an active knee joint position sense test: A pilot study

BACKGROUND

Anterior cruciate ligament (ACL) rupture is thought to alter the way in which the brain receives and processes information, affecting body movements. Although alterations in brain activity after ACL rupture have been described, these are limited to time points more than 6 months after rupture. Therefore, this pilot study aims to investigate cortical activity during an active knee joint position sense (JPS) test within the first 4 months after ACL reconstruction.

METHODS

Twelve participants with ACL reconstruction (nine males; age 25.3 ± 6.4 years; height 173.6 ± 8.0 cm; mass 71.1 ± 9.1 kg) and 12 matched healthy controls (nine males; age 28.8 ± 9.7 years; height 174.5 ± 9.7 cm; mass 72.7 ± 12.7 kg) performed an active knee JPS test in an open kinetic chain with a starting angle of 90° knee flexion and a target angle of 50°. Absolute angular error was measured with an electrogoniometer. Cortical activity was simultaneously recorded with dry electroencephalography. Participants with ACL reconstruction were measured at 5-8 weeks postoperative (M1) and 12-16 weeks postoperative (M2), the control group once. Power spectra for the frequencies, theta (4.75-6.75 Hz), alpha-1 (7.0-9.5 Hz) and alpha-2 (9.75-12.5 Hz) for frontal, central and parietal regions of interest were calculated.

RESULTS

Participants with ACL reconstruction exhibited significantly higher central theta power during JPS testing with their uninvolved leg at M1 compared with M2 (adjusted P = 0.01; rank epsilon squared = 0.39). No other comparisons yielded statistically significant differences.

CONCLUSIONS

The results cautiously support current evidence on cortical alterations following ACL reconstruction. A larger sample size and more measurement time points may provide further insight into possible alterations in the early postoperative period.

A Guideline for Validated Return-to-Sport Testing in Everyday Clinical Practice: A Focused Review on the Validity, Reliability, and Feasibility of Tests Estimating the Risk of Reinjury After ACL Reconstruction

Background

Information derived from functional return-to-sport (RTS) tests after primary anterior cruciate ligament (ACL) reconstruction (ACLR) can have a significant impact on the risk reduction of ACL reruptures. However, due to space, time, and financial limitations, few clinicians utilize objective data to assess their patients' functional abilities after ACLR.

Purpose

To identify validated and feasible RTS tests that could reliably estimate the risk of reinjury after ACLR in everyday clinical practice beyond the highly sophisticated laboratory setting.

Study Design

Systematic review; Level of evidence, 4.

Methods

A focused review was performed by experts of the committees for Ligament Injuries and Prevention/Rehabilitation of the German Knee Society. RTS functional tests, their reinjury prognostic values (if known), their reliabilities, and their implementation capacities were extracted from the original studies on the described RTS test setup, as well as from studies on potential test alternatives. These alternatives were required to be less resource-consuming yet still validated and thus able to be implemented into everyday practice. All tests were categorized according to their relevant target objective: isokinetic or isometric strength, functional (hopping and jumping) ability, or self-reported readiness.

Results

In the final analysis, 19 studies involving 7513 patients were included. From these, a total of 21 RTS tests were retrieved, and 13 tests were included. For strength testing, 2 dynamic tests and 1 static test were found to be eligible. Functional ability was represented by 8 different jump, hop, and agility tests. Tests for self-reported readiness included the ACL-Return to Sport after Injury scale and the Knee injury and Osteoarthritis Outcome Score Sport and Recreation subscore. Alternative tests included the 8-repetition maximum test, handheld/portable dynamometer, single-leg vertical (countermovement) hop with inertial sensor or smartphone app, and the drop jump with knee displacement or normalized knee distance measurement.

Conclusion

For most of the strength and functional abilities assessed by RTS tests, validated and less resource-consuming alternatives do exist. Therapists and clinicians working in nonlaboratory settings may find it helpful to select from a menu of established RTS tests and test alternatives for each relevant target objective, depending on their individual requirements.

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.

Lower-limb asymmetry in healthy male athletes

[Purpose] This study aimed to determine lower extremity asymmetry in healthy males when participating in sports where non-contact injuries are common by comparing lower extremity muscle strength, jumping distance, and change of direction speed between the dominant and non-dominant legs. [Participants and Methods] Study participants included 16 healthy males who had been playing a specific sport for at least four years at the time of measurement. We measured the maximal isometric strength of five muscle groups and conducted six performance tests. The lower-limb symmetry index was calculated as follows: (non-dominant leg/dominant leg) × 100. [Results] Significant differences were found in the strength levels of hip flexors, hip abductors, knee flexors, and knee extensor muscles. The lower-limb symmetry index for all muscles, except for the hip flexors, ranged from 91% to 98%. In the performance tests, significant differences were found in the crossover hop test and the 90° change of direction test. The lower-limb symmetry index ranged from 96% to 103% in all the performance tests. [Conclusion] We suggest that leg dominance be considered in assessments for determining return to sports based on the type of tests employed.

Knee joint mechanics during gait after anterior cruciate ligament reconstruction using a partial or full thickness quadriceps tendon autograft at 2 years after surgery

BACKGROUND

Despite quadriceps weakness in individuals after quadriceps tendon anterior cruciate ligament reconstruction (QT-ACLR), and its association with knee joint mechanics, no studies have addressed gait mechanics in both partial-thickness (PT-Q) and full-thickness (FT-Q) options for QT-ACLR.

OBJECTIVE

To assess gait mechanics across a QT-ACLR cohort. We hypothesized that QT-ACLR would show changes in knee joint mechanics compared to control participants (CON) and nonoperated limbs. Additionally, we hypothesized that FT-Q operated limbs would show greater changes compared to PT-Q and CON.

DESIGN

Retrospective cohort study.

SETTING

University-affiliated sports medicine institute.

PARTICIPANTS

Sixteen patients who underwent QT-ACLR (7 FT-Q: Age (years) = 28.6 ± 7.3, post-op (months) = 23.5 ± 10.7, 9 PT-Q: Age = 25.2 ± 4.3, post-op = 24.4 ± 11.7) were recruited and compared to 11 CON (age = 23.4 ± 4.8).

INTERVENTION

Participants underwent gait testing with force plate integrated motion capture.

MAIN OUTCOME MEASURES

Mixed repeated-measures analyses of covariance, adjusted for gait speed, were used to determine significant main effects or interactions in peak knee flexion angle, sagittal knee range of motion, peak internal knee extension moment (KEM), and peak internal knee flexion moment.

RESULTS

When measured an average of 2 years after surgery, no main effect for limb or limb by depth interaction were detected. A significant effect by group was observed for peak KEM (p = .03, η2 = .27) and peak knee flexion angle (p = .04, η2 = .24) in the loading response phase. FT-Q (p = .02) and PT-Q (p = .03) showed lower KEM compared to the CON group in both limbs. The FT-Q group showed lower peak knee flexion angle compared to the CON group (p = .01).

CONCLUSIONS

Knee joint symmetry may be recovered 2 years following QT-ACLR, but lower KEM compared to CON for both graft options and lower peak knee flexion angle than CON for the FT-Q group may indicate a need for further investigation in QT-ACLR.

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

BACKGROUND

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

HYPOTHESIS

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

STUDY DESIGN

Case control.

LEVEL OF EVIDENCE

Level 4.

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

Clinicians should assess psychological readiness during rehabilitation after ACLR.

Anterior Cruciate Ligament Reconstruction Return to Sport Testing Passing Rates for Healthy People: A Systematic Review

BACKGROUND

Return to sport (RTS) is a common goal after anterior cruciate ligament (ACL) reconstruction (ACLR) but carries a relatively high risk of reinjury with up to 20% to 25% of athletes experiencing graft rupture or contralateral ACL tear. While there is increased emphasis on establishing safe RTS criteria for athletes to return to previous activity levels, studies show that even healthy individuals have difficulty passing RTS testing.

PURPOSE

To synthesize data concerning whether healthy individuals can pass ACLR RTS rehabilitation tests.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Following the established PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the authors conducted a systematic literature search in May 2023. Three databases were used in the search (PubMed, EMBASE, and SPORTDiscus) to retrieve all studies that conducted ACLR RTS rehabilitation tests on healthy individuals. Tests included were isometric strength, isokinetic strength, hop, and balance tests. The search was performed in duplicate, and a quality assessment of all studies was included.

RESULTS

A total of 1724 studies were retrieved, of which 32 were included, involving 1552 controls with no history of ACL injury. From the studies analyzed, 5.3% to 42.2% of healthy participants failed 6 different hop tests, 15.2% failed the Star Excursion Balance Test, 37% failed the isometric knee flexion test, 50% failed the isometric knee extension test, and 23.7% to 28.9% failed the drop vertical jump test. An asymmetry index ≥10% was found in 6 of the 18 isokinetic tests and 2 of the 14 isometric tests. Hop testing was the most common test in the included studies (56.3%), followed by balance testing (31.3%), isometric strength testing (31.3%), isokinetic strength testing (25%), and drop vertical jump (6.3%).

CONCLUSION

Many healthy individuals fail ACLR RTS tests, with some having an inherent variation from side to side that is >10%. The passing threshold for RTS testing should be a value that is practical yet helps reduce reinjury rates.

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.

Return to Sport Following Anterior Cruciate Ligament Reconstruction: A Scoping Review of Criteria Determining Return to Sport Readiness

PURPOSE OF REVIEW

Provide a concise review of currently utilized functional metrics and patient reported outcomes measures (PROMs) determining appropriate return to sport following anterior cruciate ligament reconstruction (ACLR).

RECENT FINDINGS

When determining return to sport following ACLR, a limb symmetry index (LSI) ≥ 90% when compared to the contralateral extremity is the most commonly reported functional metric. LSI is most commonly assessed using isokinetic quadriceps strength, followed by single-leg vertical hop and cross-over hop test. A minimum ACL-Return to Sport Index (ACL-RSI) score of 68.2 was reported, as well as a mean International Knee Documentation Committee (IKDC) score of 88.3%. A minimum Knee Injury and Osteoarthritis Outcome Score-Quality of Life (KOOS-QoL) of 62.5% was reported in a single investigation. There remains limited data on reported metrics guiding return to sport following ACLR. Evaluation of LSI when compared to the contralateral extremity is the most commonly reported functional measure, with ACL-RSI, IKDC and KOOS-QoL also being reported. Further investigations examining return to sport rate and the incidence of recurrent injury, factoring in differences in sex, competition level, and the presence or absence of concomitant meniscal injuries, based on functional metrics and PROMs is warranted to better understand which outcome measures are predictive of successful return to sport following ACLR.

Lack of association between revision ACL reconstruction and preoperative, intraoperative and post-operative factors at primary ACL reconstruction in children and adolescents

PURPOSE

To evaluate factors associated with revision anterior cruciate ligament reconstruction (ACLR) within 5 years of primary ACLR in children and adolescents.

METHODS

Children and adolescents (age <20 years at surgery) who underwent primary hamstring tendon ACLR at the Capio Artro Clinic, Stockholm, Sweden, between January 2005 and December 2018 were identified. Revision ACLR within 5 years of primary ACLR was captured in the Swedish National Knee Ligament Registry. Univariable and multivariable logistic regression analyses were used to evaluate the associations between revision ACLR and preoperative (age, sex, body mass index, time from injury to surgery, pre-injury Tegner activity level, medial collateral ligament injury, passive contralateral knee hyperextension [≤-5°]), intraoperative (medial meniscus and lateral meniscus [LM] resection or repair, cartilage injury and graft diameter) and post-operative (KT-1000 side-to-side anterior knee laxity, limb symmetry index for extension and flexion strength and single-leg-hop (SLH) test performance at 6 months) factors at primary ACLR.

RESULTS

A total of 1888 patients (mean age: 16.0 ± 2.0, range: 8-19 years) who underwent primary ACLR were included. The overall incidence of revision ACLR within 5 years was 9.0% (170 out of 1888). Univariable analysis revealed that a time from injury to primary ACLR of <5 months (odds ratio [OR]: 2.27, 95% confidence interval [CI]: 1.61-2.35, p < 0.001) and LM resection (OR: 1.49, 95% CI: 1.00-2.20, p = 0.04) increased the odds of revision ACLR. Multivariable analysis showed that revision ACLR was significantly associated only with a time from injury to primary ACLR of <5 months (OR: 2.56, 95% CI: 1.72-3.70, p < 0.001).

CONCLUSION

There was a lack of association between revision ACLR and preoperative, intraoperative and post-operative factors at primary ACLR in children and adolescents. A time from injury to primary ACLR of <5 months was the only factor associated with revision ACLR within 5 years.

LEVEL OF EVIDENCE

Level III.

Physiologic Preoperative Knee Hyperextension Is Not Associated With Postoperative Laxity, Subjective Knee Function, or Revision Surgery After ACL Reconstruction With Hamstring Tendon Autografts

BACKGROUND

There is concern that physiologic knee hyperextension may be associated with inferior outcomes after anterior cruciate ligament reconstruction (ACLR) using hamstring tendon (HT) autografts.

PURPOSE

To assess whether there is an association between contralateral passive preoperative knee hyperextension (≤-5°) and postoperative anterior knee laxity, subjective knee function, or revision surgery after ACLR using HT autografts.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients without concomitant ligament injuries who underwent primary ACLR using an HT autograft at Capio Artro Clinic, Stockholm, Sweden, between January 1, 2005, and December 31, 2018, were identified. The cohort was dichotomized into the hyperextension group (≤-5°) and the no hyperextension group (>-5°) depending on preoperative contralateral passive knee extension degree. Anterior knee laxity (KT-1000 arthrometer; 134 N) was assessed preoperatively and at 6 months postoperatively. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and at 1, 2, and 5 years postoperatively. Patients who underwent revision ACLR at any institution in Sweden within 5 years of the primary surgery were identified in the Swedish National Knee Ligament Registry.

RESULTS

A total of 6104 patients (53.5% male) for whom knee range of motion measurements were available were identified (hyperextension group [≤-5°]: 2350 [38.5%]; mean extension, -6.1°± 2.3° [range, -20° to -5°]; no hyperextension group [>-5°]: 3754 [61.5%]; mean extension, 0°± 1.4° [range, -4° to 15°]). There were no intergroup differences in anterior knee laxity preoperatively (hyperextension group, 3.6 ± 2.8 mm; no hyperextension group, 3.7 ± 2.7 mm; P = .24) or postoperatively (hyperextension group, 1.8 ± 2.3 mm; no hyperextension group, 1.8 ± 2.2 mm; P = .41). The only significant but nonclinically relevant intergroup differences were seen in the KOOS Symptoms subscale at the 1-year follow-up (hyperextension group, 81.4 ± 16.0; no hyperextension group, 80.3 ± 16.5; P = .03) and in the Sport and Recreation subscale at the 5-year follow-up (hyperextension group, 73.0 ± 25.6; no hyperextension group, 75.7 ± 24.3; P = .02). No other significant intergroup differences were noted preoperatively or at 1, 2, or 5 years postoperatively in any of the KOOS subscales. The overall revision ACLR rate at ≤5 years after the primary surgery was 4.9% (302 of 6104 patients). The hazard for revision ACLR in the no hyperextension group (4.5%; 170 of 3754 patients) was not significantly different from that in the hyperextension group (5.6%; 132 of 2350 patients) (hazard ratio, 0.89; 95% CI, 0.71 to -1.12; P = .34). A subsequent subanalysis showed that the hazard of revision ACLR in patients with no hyperextension was not significantly different from that of patients with ≤-10° of extension (5.8%; 27 of 467 patients) (hazard ratio, 0.91; 95% CI, 0.61 to 1.36; P = .65).

CONCLUSION

Preoperative passive contralateral knee hyperextension (≤-5°) was not associated with postoperative anterior knee laxity, subjective knee function, or revision surgery ≤5 years after ACLR using HT autografts. Therefore, the presence of knee hyperextension alone should not be considered a contraindication per se for the use of HT autografts in ACLR.

Effective Prevention and Rehabilitation Strategies to Mitigate Non-Contact Anterior Cruciate Ligament Injuries: A Narrative Review

Non-contact anterior cruciate ligament injuries (NC-ACLs) represent a significant concern in sports medicine, particularly among athletes and physically active individuals. These injuries not only result in immediate functional impairment but also predispose individuals to long-term issues such as recurrent instability and early-onset osteoarthritis. This narrative review examines the biomechanical, neuromuscular, and environmental factors that contribute to the high incidence of NC-ACLs and evaluates the effectiveness of current prevention and rehabilitation strategies. The review identifies key risk factors, including improper landing mechanics, deficits in neuromuscular control, and muscle imbalances, which are pivotal in the etiology of NC-ACLs. Prevention programs that incorporate plyometric exercises, strength training, and neuromuscular education have shown efficacy in reducing injury rates. Rehabilitation protocols that emphasize a gradual return to sport, focusing on pain management, restoration of range of motion, and progressive strengthening, are critical for successful recovery and prevention of re-injury. The evidence suggests that an integrated approach, combining prevention and rehabilitation strategies tailored to the individual, is essential for minimizing NC-ACL risk and improving outcomes in affected populations.

A systematic review of the efficacy of neural mobilisation in sport: A tool for the neural tension assessment

INTRODUCTION

Any sport places great physical demands on the lower limbs and lumbar spine. Sport can lead to nerve entrapment syndromes, making nerve tissue a target for therapeutic intervention.

METHODS

A systematic review of clinical trials and cohort studies using neurodynamics as a method of assessment and treatment in sports patients was conducted. Risk of bias was assessed using the PEDro and NOS scales.

RESULTS

Ten studies were eventually included in this study. Age ranged from 18 to 33 years. Neural tension is underappreciated in sport as a risk factor for injury. Treatment of nerve tissue included glide/tension type neural mobilisations. Studies ranged from 3 to 8 sets, 5 to 20 repetitions, with a time of 60 s and 1-6 weeks of treatment.

CONCLUSIONS

Neurodynamics manoeuvres proves to be most beneficial in increasing range of motion and decreasing perceived muscle tension in the athlete population. A significant effect was also observed in the monopodal jump test, the 6-m jump test and the cross-jump test. There is also limited and scarce evidence on the use of neural testing in sports injuries.Further studies on the application and assessment of neural stress in sport are warranted.

Quadriceps tendon size does not affect postoperative strength recovery following quadriceps tendon anterior cruciate ligament reconstruction

OBJECTIVE

The influence of quadriceps tendon (QT) size on postoperative quadriceps strength following QT anterior cruciate ligament reconstruction (ACLR) is unclear. Therefore, this study aimed to determine the relationship between QT morphology and postoperative quadriceps strength recovery following primary ACLR using a QT autograft.

METHODS

Patients who underwent primary ACLR using QT autograft from 2014 to 2022 followed by a postoperative isometric strength measurement between 5 and 8 months were retrospectively reviewed. Using preoperative magnetic resonance imaging findings, the anterior-posterior (A-P) thickness, medial-lateral (M-L) width, and cross-sectional area (CSA) of the QT were measured. Postoperative residual CSA of QT was estimated based on the graft-harvest diameter. The quadriceps index (QI) was also calculated, which was determined by dividing the maximum isometric quadriceps torque on the involved side by the maximum quadriceps torque on the uninvolved side. Associations between the QI and QT morphology were assessed. Furthermore, multivariable logistic regression analysis with the addition of sex as a covariate was performed with the addition of each individual measure of QT morphology to determine the association with a QI ​≥80%.

RESULTS

A total of 84 patients (mean age: 21.9 ​± ​7.3 years; 46 female) were included. Residual CSA showed a statistically significant positive correlation with the QI (r ​= ​0.221, p ​= ​0.043). There were no statistically significant correlations between QI and CSA, A-P thickness, or M-L width. Multivariable logistic analysis adjusting for sex demonstrated that each individual measure of QT morphology was not statistically significantly associated with a QI ​≥80%.

CONCLUSION

A statistically significant correlation between measures of preoperative QT size and postoperative quadriceps strength were not detected in patients undergoing primary QT autograft ACLR. A smaller residual QT CSA based on QT harvest diameter was weakly associated with decreased quadriceps strength 5-8 months postoperatively, but this association was not independent of sex. Future studies examining the impact of QT morphology on quadriceps strength at longer follow-up intervals are needed.

LEVEL OF EVIDENCE

IV.

Successful ACL repair by dynamic intraligamentary stabilisation is non-inferior in functional performance and worse in proprioception compared to healthy controls in a case-matched study

Purpose

The primary aim of this study was to assess non-inferiority in functional performance of the knee after dynamic intraligamentary stabilisation (DIS) surgery at a minimal follow-up of 1 year compared to healthy controls, based on limb symmetry index (LSI) of the single leg hop test (SLH). Additionally, functional performance based on the single leg triple hop test (SLTH) and side hop test (SH), proprioception and subjective outcome were evaluated.

Methods

A total of 45 DIS patients were 1-to-1 matched to a healthy control. Functional performance was evaluated by LSI and absolute values on the SLH, SLTH and SH. Proprioception was assessed by joint position sense (JPS) test and International Knee Documentation Committee (IKDC) scores were obtained.

Results

Non-inferiority in functional performance after DIS compared to healthy controls was confirmed based on the mean LSI of the SLH and SLTH (97.6% vs. 99.6% and 97.5% vs. 100.6%, respectively) and non-confirmed on the SH (98.8% vs. 100.0%, respectively). No significant differences were found in absolute value of the SLH and SLTH and a significantly higher absolute value of the SH was found in the DIS group (p = 0.01). JPS absolute angular error was significantly higher in the DIS group compared to the control group (p = 0.01). The median IKDC score of the DIS group was significantly lower (92, IQR 85-95) than the control group (100, IQR 99-100), p < 0.001.

Conclusions

In conclusion, functional performance after DIS was confirmed non-inferior compared to healthy controls based on the SLH and SLTH, although non-confirmed on the SH.

Level of evidence

Level III.

Agonist-antagonist myoneural interface surgery on the proprioceptive reconstruction of rat hind limb

Currently, prosthesis users rely on visual cues to control their prosthesis. One reason for this is that prostheses cannot provide users with proprioceptive functional signals. For this reason, we propose an agonist-antagonist myoneural interface (AMI) surgery. We examined how this surgery affects the restoration of motor function and proprioceptive reconstruction in the hind limb of Sprague-Dawley rats. The procedure entails grafting the soleus muscle, suturing the two tendon ends of the soleus muscle, and anastomosing the tibial and common peroneal nerves to the soleus muscle. We found that, following surgery, AMI rats exhibited improved neurological repair, shorter walking swings, braking, propulsion, and stance times, and greater compound action potentials than control rats. This means that in rats with neurological impairment of the hind limb, the proposed AMI surgical method significantly improves postoperative walking stability and muscle synergy. AMI surgery may become an option for regaining proprioception in the lost limb.

Predicting the Recovery of Isokinetic Knee Strength 6 Months After Anterior Cruciate Ligament Reconstruction

Background

The limb symmetry index (LSI) is a metric of strength restoration. It is key to successfully return to sports after anterior cruciate ligament (ACL) reconstruction. The threshold for return to sports is generally considered an LSI of ≥85%.

Purpose

To develop a statistical model for predicting the recovery of knee extension and flexion strength (with LSI ≥85%) at 6 months after ACL reconstruction.

Study Design

Case-control study; Level of evidence: 3.

Methods

Patients who underwent arthroscopic ACL reconstruction between November 2015 and December 2020 were included. The patients were classified into 2 groups: "pass" if the LSI at 6 months postoperatively was ≥85% and "fail" if the LSI was <85%. Factors in 25 categories with 74 levels, including patient characteristics, periarticular procedures, intra-articular lesions and treatment, and perioperative management, were collected. A multivariable logistic regression combined with backward variable elimination was used to determine the predictive parameters for recovery of knee extension and flexion strength.

Results

A total of 948 patients were included. Graft site, preoperative isokinetic strength, treatment of meniscal injury, and injured side (left vs right) were identified as general predictors for both knee extension and flexion strength. For knee extension strength, age at injury and partial weightbearing duration were identified as additional predictors. For knee flexion strength, type of meniscal injury, surgeon volume, cartilage procedures, and periarticular procedures were identified as additional predictors. The Nagelkerke R 2 of the final model was 0.178, and the c-statistic was 0.716 (95% CI, 0.676-0.754). The Hosmer-Lemeshow test indicated good calibration (P = .879).

Conclusion

Several factors including preoperative isokinetic strength, treatment of meniscal injuries, left vs. right side and graft site were found to predict recovery of ≥85% LSI in knee extension and flexion strength. Despite the numerous factors that were analyzed, the predictive power was moderate (c-statistic = 0.716), indicating there were other nonincluded factors that significantly influence strength performance at 6 months postoperatively.

Impaired Symmetry in Single-Leg Vertical Jump and Drop Jump Performance 7 Months After ACL Reconstruction

Background

Anterior cruciate ligament reconstruction (ACLR) continues to be associated with a variable rate of return to sports and a concerning rate of further anterior cruciate ligament injury. Persistent functional deficits may explain these results and support the need to keep exploring lower limb functional indexes, especially during vertical jumping. This would help improve rehabilitation through the return-to-sports continuum and improve postoperative outcomes.

Hypothesis

Vertical jumping performance indexes are impaired among patients 7 months after ACLR.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A total of 202 patients who underwent ACLR and 50 healthy participants performed single-leg vertical jump (SLVJ) and single-leg drop jump (SLDJ) testing. Jump height (H) as well as reactive strength index (RSI) were assessed and the limb symmetry index (LSI) of each parameter was compared between both groups. Vertical jumping indexes were also compared between healthy participants and the injured and contralateral legs of ACLR patients. Frequency analysis (chi-square test) of participants exhibiting an LSI >90% for each parameter was calculated in both groups. The level of association between SLVJ-H, SLDJ-H, and SLDJ-RSI was evaluated using the Pearson coefficient (r).

Results

At 6.6 ± 0.7 months (mean ± SD) postoperatively, participants after ACLR exhibited poorer LSI than the control group for all parameters (79.1 ± 14.8 vs 93.9 ± 4.5, 77.3 ± 14.6 vs 93.4 ± 5.2, and 71.9 ± 17.4 vs 93.4 ± 3.8; all P < .001; for the SLVJ-H, SLDJ-H, and SLDJ-RSI, respectively). Vertical jumping performance was lower on both injured and contralateral legs compared with healthy participants (all P < .001). Only 27%, 25%, and 16% of the ACLR patients exhibited an LSI >90% for the SLVJ-H, SLDJ-H, and SLDJ-RSI, respectively, in comparison with 80%, 72%, and 86% in the control group. Moderate correlations were observed between SLDJ-H and SLVJ-H (r = 0.494; P < .001) as well as between SLDJ-RSI and SLVJ-H (r = 0.488; P < .001) in the ACLR group.

Conclusion

Vertical jumping indexes (both symmetry and absolute values) were highly impaired 7 months after ACLR. Deficits were more marked for reactive strength ability. Clinicians should focus on restoring vertical jumping abilities to improve functional performance after ACLR.

Athletes Continue to Show Functional Performance Deficits at Return to Sport After Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To systematically review the existing literature on the functional performance of athletes at the time of return-to-sport (RTS) clearance after anterior cruciate ligament reconstruction (ACLR).

METHODS

A systematic literature search of the MEDLINE, EMBASE, Scopus, and Web of Science databases was performed. The inclusion criteria were original research reports with study populations of athletes who had undergone ACLR and had undergone objective functional testing immediately after clearance to RTS. Functional testing was stratified by hop tests, strength tests, kinetic assessment, and kinematic assessment, and data were extracted from each study using a standardized template.

RESULTS

Of the 937 unique studies identified, 46 met the inclusion criteria. The average time between ACLR and functional testing was 7.9 months among the included studies. In 10 of 17 studies, patients were found to have an average quadriceps strength limb symmetry index of less than 90%. However, only 2 of 12 studies found the average hop test limb symmetry index to be less than 90%. Kinematics included reduced knee flexion angle and increased trunk flexion on landing in ACLR patients compared with matched controls. On evaluation of kinetics, ACLR patients showed reduced peak vertical ground reaction force, lower peak knee extension and knee flexion moments, and altered energy absorption contribution compared with matched controls.

CONCLUSIONS

This systematic review suggests that athletes show functional deficits at the time of RTS at an average of 7.9 months after ACLR. Traditional functional tests, such as strength and hop tests, are not able to accurately identify patients who continue to show deficits. The most common biomechanical deficits that persist after RTS clearance include diminished peak knee extension moment, decreased knee flexion angle, increased trunk flexion angle, reduced vertical ground reaction force, and increased hamstring central activation ratio during various functional gait and landing tasks.

LEVEL OF EVIDENCE

Level III, systematic review of Level I to III studies.

Evaluation of Lower Limb Asymmetry Index Based on the 30-Second Skater Squat Functional Test in Young Men

Introduction: Physical performance tests (PPTs) are used for the pre-season evaluation of athletes and to monitor and control the rehabilitation process. PPTs include single-leg jumps, single-leg squats, and balance tests. One of the physical fitness tests is the skater squat test. The 30 s skater squat functional test (SSFT) is used as one of the tests to assess fitness and symmetry in the lower limbs. The present study aimed to calculate and compare the asymmetry index using the 30 s skater squat functional test, the single-leg distance jump test, and the isometric measurement of knee joint extensor strength. Materials and Methods: The study examined 25 men aged 23 ± 3.17 years. The study used the 30 s SSFT, the single-leg long jump test (SLLJT), and an isometric dynamometer test to measure peak moment of force values for extensors of the knee using the JBA Zbigniew Staniak® measuring station ("JBA" Zb. Staniak, Poland). The statistical analysis of functional test results and iso-metric dynamometry results was based on correlation analysis. Results: There was a moderate correlation between 30 s SSFT and SLLJT (r = 0.540), and between SLLJT and measurements of peak moment of force of the knee joint extensors (r = 0.533). Conclusions: The asymmetry index calculated based on functional tests and peak moment of force of the knee extensors in a group of young men should not be used interchangeably. The asymmetry index calculated from the 30 s skater squat functional test detects greater differences in knee extensor strength than the ASI index calculated from the single-leg long jump test in a group of young male athletes. The practical significance of this study was that its results could play an important role in the training process and monitoring the return to sports after a possible injury.

A High Grade of Postoperative Knee Laxity Is Associated With an Increased Hazard of Revision Surgery: A Cohort Study of 4697 Patients With Primary ACL Reconstruction

BACKGROUND

There is still debate regarding the association between arthrometric knee laxity measurements and subjective knee outcome and revision surgery after primary anterior cruciate ligament reconstruction (ACLR).

PURPOSE

To assess whether arthrometric knee laxity (measured with the KT-1000 arthrometer) 6 months after primary ACLR was associated with the 1-, 2-, and 5-year subjective knee outcomes or revision ACLR at a 5-year follow-up.

STUDY DESIGN

Cohort study, Level of evidence 3.

METHODS

Patients who underwent primary ACLR with a hamstring tendon autograft at the authors' institution between January 1, 2005, and December 31, 2017, with no concomitant ligamentous injuries, were identified. Anterior knee laxity (KT-1000 arthrometer, 134 N) was assessed 6 months postoperatively. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and 1, 2, and 5 years postoperatively. Patients who underwent revision ACLR at any institution in the country within 5 years of primary surgery were identified through the Swedish National Knee Ligament Registry.

RESULTS

A total of 4697 patients (54.3% male) with available KT-1000 arthrometer measurements were included (normal: side-to-side [STS] ≤2 mm, 3015 [64.2%]; nearly normal: STS 3-5 mm, 1446 [30.8%]; abnormal: STS >5 mm, 236 [5.0%]). The only significant difference in subjective knee outcome between the groups was for the KOOS Symptoms subscale at the 1-year follow-up (STS ≤2 mm, 79.9 ± 16.2; STS 3-5 mm, 82.5 ± 14.8; STS >5 mm, 85.1 ± 14.2; P < .001). No other significant differences between the groups were found preoperatively or at 1, 2, or 5 years postoperatively for any of the KOOS subscales. The hazard for revision ACLR within 5 years of the primary surgery was significantly higher for the groups with an STS of 3 to 5 mm (6.6%; 95/1446) (hazard ratio [HR], 1.42; 95% CI, 1.07-1.87; P = .01) and an STS >5 mm (11.4%; 27/236) (HR, 2.61; 95% CI, 1.69-4.03; P < .001) compared with the group with an STS ≤2 mm (3.8%; 116/3015).

CONCLUSION

A high grade of postoperative knee laxity (STS 3-5 mm and STS >5 mm) 6 months after primary ACLR was associated with an increased hazard of revision ACLR within 5 years, but it was not associated with an inferior subjective knee outcome.

Evaluation of Outcomes After Anterior Cruciate Ligament Reconstruction: What We Know, What We Have, and What to Consider

Measurement of success following anterior cruciate ligament reconstruction (ACLR) hinges on the appropriate use of high quality and meaningful outcome measures. We identified and categorized over 100 outcome measures for ACLR using the International Classification of Functioning, Disability and Health (ICF) model. The ICF model is a useful framework to facilitate decisions about outcome selection and describe recovery following ACL injury. We outline key considerations when selecting outcome measures during study design (purpose, measurement properties, sample size, global assessment) or evaluating reported outcomes (measurement properties, sample size, magnitude/precision, clinical relevance, applicability), and discuss challenges in outcome measurement following ACLR.

Limited correlation between physical performance and patient-reported outcomes at 1-year follow-up after anterior cruciate ligament reconstruction

Purpose

The majority of anterior cruciate ligament reconstruction (ACLr) patients wish to return to sport. Clinical evaluations after ACLr often do not include physical testing, making it difficult to determine the patient's readiness to return to sport. Thus, it would be helpful to identify easily assessable factors associated with physical function in ACLr patients that could inform planning of patients' return to sport. This study sought to evaluate the associations between physical test performance in ACLr patients and known ACL injury risk factors, knee laxity and patient-reported outcomes at 1-year follow-up.

Methods

The cohort included isolated primary ACLr patients operated between 2009 and 2014. Patients were invited to a 1-year visit to clarify their readiness to return to sport. A test battery was performed, including clinical evaluation, patient-reported outcomes and three physical tests, from which the Leg Symmetry Index (LSI) was calculated. Multivariate regression analyses were performed for each of the physical tests, including known risk factors, clinical outcomes and patient-reported outcomes. Laxity <3 mm, pivot shift = 0, Knee Injury and Osteoarthritis Outcome Score (KOOS) sport >75, International Knee Documentation Committee (IKDC) >75.9, and Single Assessment Numeric Evaluation (SANE) >92.7 were applied as cut-off values for good versus poor status.

Results

A total of 480 ACLr patients were included in the study. Laxity <3 mm had a negative impact on the single-hop LSI, whereas a pivot shift = 0 or IKDC >75.9 had a positive impact on the single-hop LSI. Age <20, a pivot shift grade of 0 and KOOSsport >75 were positively associated with the triple-hop LSI. Finally, age <20 and IKDC >75.9 were positively associated with the leg extension strength LSI.

Conclusions

Age, sagittal laxity, pivot shift and patient-reported outcomes were associated with physical test performance 1 year after ACLr. However, the associations were not completely uniform and strong, so information on age, sagittal laxity, pivot shift and patient-reported outcomes cannot replace a return-to-sport functional test battery in determining when it is safe to return to sport after ACLr.

Level of Evidence

Level III.

Effect of Sampling Rate, Filtering, and Torque Onset Detection on Quadriceps Rate of Torque Development and Torque Steadiness

Quadriceps rate of torque development (RTD) and torque steadiness are valuable metrics for assessing explosive strength and the ability to control force over a sustained period of time, which can inform clinical assessments of knee function. Despite their widespread use, there is a significant gap in standardized methodology for measuring these metrics, which limits their utility in comparing outcomes across different studies and populations. To address these gaps, we evaluated the influence of sampling rates, signal filtering, and torque onset detection on RTD and torque steadiness. Twenty-seven participants with a history of a primary anterior cruciate ligament reconstruction (N = 27 (11 male/16 female), age = 23 ± 8 years, body mass index = 26 ± 4 kg/m2) and thirty-two control participants (N = 32 (13 male/19 female), age = 23 ± 7 years, body mass index = 23 ± 3 kg/m2) underwent isometric quadriceps strength testing, with data collected at 2222 Hz on an isokinetic dynamometer. The torque-time signal was downsampled to approximately 100 and 1000 Hz and processed using a low-pass, zero-lag Butterworth filter with a range of cutoff frequencies spanning 10-200 Hz. The thresholds used to detect torque onset were defined as 0.1 Nm, 1 Nm, and 5 Nm. RTD between 0 and 100 ms, 0 and 200 ms, and 40-160 ms was computed, as well as absolute and relative torque steadiness. Relative differences were computed by comparing all outcomes to the "gold standard" values computed, with a sampling rate of 2222 Hz, a cutoff frequency in the low-pass filter of 150 Hz, and torque onset of 1 Nm, and compared utilizing linear mixed models. While all combinations of signal collection and processing parameters reached statistical significance (p < 0.05), these differences were consistent between injured and control limbs. Additionally, clinically relevant differences (+/-10%) were primarily observed through torque onset detection methods and primarily affected RTD between 0 and 100 ms. Although measurements of RTD and torque steadiness were generally robust against diverse signal collection and processing parameters, the selection of torque onset should be carefully considered, especially in early RTD assessments that have shorter time epochs.

Residual deficits of knee and hip joint coordination and clinical performance after return to sports in athletes with anterior cruciate ligament reconstruction

BACKGROUND

Biomechanical changes and neuromuscular adaptations have been suggested as risk factors of secondary injury in individuals after anterior cruciate ligament reconstruction (ACLr). To achieve a better understanding of preventive mechanisms, movement quality is an important factor of consideration. Few studies have explored time-series analysis during landing alongside clinical performance in injured and non-injured individuals. The purpose of the study was to investigate the biomechanical risks of recurrent injury by comparing clinical and jump-landing performance assessments between athletes with ACLr and healthy controls.

METHOD

This study was observational study. Sixteen athletes with and without ACLr voluntarily participated in clinical and laboratory measurements. Single-leg hop distance, isokinetic tests, landing error score, and limb symmetry index (LSI) were included in clinical report. Lower limb movements were recorded to measure joint biomechanics during multi-directional landings in motion analysis laboratory. Hip-knee angle and angular velocity were explored using discrete time-point analysis, and a two-way mixed analysis of variance (2 × 4, group × jump-landing direction) was used for statistical analysis. Time series and hip-knee coordination analyses were performed using statistical parametric mapping and descriptive techniques.

RESULTS

Significantly lower single-leg hop distance was noted in ACLr group (158.10 cm) compared to control group (178.38 cm). Although the hip and knee moments showed significant differences between four directions (p < 0.01), no group effect was observed (p > 0.05). Statistical parametric mapping showed significant differences (p ≤ 0.05) between groups for hip abduction and coordinate plot of hip and knee joints. Athletes with ACLr demonstrated a higher velocity of hip adduction. Time-series analysis revealed differences in coordination between groups for frontal hip and knee motion.

CONCLUSIONS

Athletes with ACLr landed with poor hip adduction control and stiffer knee on the involved side. Multi-directions landing should be considered over the entire time series, which may facilitate improved movement quality and return to sports in athletes with ACLr.

Transphyseal ACL reconstruction and tenodesis in skeletally immature patients demonstrates encouraging clinical scores, without growth disturbance, excessive laxity or re-injury

Purpose

Paediatric patients demonstrate high re-rupture rates after anterior cruciate ligament reconstruction (ACLR), with numerous surgical techniques proposed to deal with this challenging cohort. This study investigated the early clinical outcomes, complications, return to sport (RTS) and re-rupture rates up until 2-years post-surgery in paediatric patients presenting with open growth plates undergoing transphyseal ACLR that was combined with an extra-articular tenodesis (LET).

Methods

Between October 2017 and September 2020, 20 skeletally immature patients were consecutively recruited and underwent transphyseal ACLR and LET. Patient reported outcome measures (PROMs), KT-1000 laxity, knee range of motion (ROM), maximal isokinetic knee torque and a 3-hop battery were assessed at 6-, 12- and 24-months. Limb Symmetry Indices (LSIs), RTS rates, complications, re-ruptures and re-operations were reviewed.

Results

All PROMs improved (p < 0.05). No change (p = 0.903) in laxity between limbs was seen, while 18 patients (90%) demonstrated normal (<3 mm) or near normal (3-5 mm) laxity differences. Peak knee flexion ROM improved over time (p = 0.028), while LSIs for knee extensor strength (p < 0.001), the single (p = 0.002) and triple crossover (p = 0.038) hop tests improved. At 24 months, 18 patients (90%) were participating in their pre-injury pivoting sport activities. No complications, growth disturbances, re-injuries or subsequent surgeries were observed.

Conclusions

Transphyseal ACLR combined with LET, undertaken in skeletally immature paediatric patients, demonstrated high scoring PROMs, physical performance and RTS overall, without evidence of growth disturbance or excessive graft laxity. No re-injuries have been observed at this time with ongoing review required in this high-risk cohort.

The Addition of the Gracilis Tendon to a Semitendinosus Tendon Autograft Is Not Associated With Knee Muscle Strength, Subjective Knee Function, or Revision Surgery After Anterior Cruciate Ligament Reconstruction

PURPOSE

To evaluate and compare isokinetic knee muscle (extension and flexion) strength, single-leg hop (SLH) test performance, anterior knee laxity, subjective knee function, and the 2-year revision surgery risk between patients who underwent anterior cruciate ligament reconstruction (ACLR) with semitendinosus tendon (ST) autografts and patients who underwent ACLR with ST and gracilis tendon (ST-G) autografts.

METHODS

We identified patients aged 16 years or older who underwent primary ACLR with hamstring tendon autografts at our institution from January 2005 to December 2020 and had no associated ligament injuries. Isokinetic knee muscle strength and SLH test performance were assessed 6 months postoperatively. Anterior knee laxity (KT-1000 arthrometer, 134 N) was assessed preoperatively and 6 months postoperatively. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and 1 and 2 years postoperatively. Patients who underwent revision ACLR at any institution in Sweden within 2 years of primary surgery were identified through the Swedish National Knee Ligament Registry.

RESULTS

A total of 6,974 patients (5,479 with ST and 1,495 with ST-G) were included. There were no significant differences in extension and flexion strength or SLH test performance between the groups. Preoperatively, there was no significant difference in knee laxity between the ST and ST-G groups. Postoperatively, the ST-G group had significantly increased mean side-to-side (STS) laxity (2.1 ± 2.3 mm vs 1.7 ± 2.2 mm, P < .001) and showed a trend toward increased STS laxity according to the International Knee Documentation Committee form, with significantly fewer patients with STS laxity of 2 mm or less (58.4% vs 65.8%) and significantly more patients with STS laxity between 3 and 5 mm (35.0% vs 29.9%) or greater than 5 mm (6.6% vs 4.3%) (P < .001). The only significant difference in subjective knee function was for the KOOS Quality of Life subscale score in favor of the ST group preoperatively (37.3 ± 21.4 vs 35.1 ± 19.9, P = .001). No other significant differences between the groups were found preoperatively and 1 and 2 years postoperatively for any of the KOOS subscales. The overall revision ACLR rate within 2 years of primary surgery was 2.0% (138 of 6,974 patients). The revision ACLR risk in the ST-G group (1.7%, 25 of 1,495 patients) was not significantly different from that in the ST group (2.1%, 113 of 5,479 patients) (hazard ratio, 0.80; 95% confidence interval, 0.50-1.24; P = .32).

CONCLUSIONS

The addition of the gracilis tendon to an ST autograft was not associated with knee muscle strength, SLH test performance, subjective knee function, or the risk of revision surgery after ACLR.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Rehabilitation Following ACL Repair with Internal Brace Ligament Augmentation in Female Gymnast: A Resident's Case Report

Introduction

Anterior Cruciate Ligament (ACL) injuries continue to be a major source of morbidity in gymnastics. The gold standard is to perform an ACL Reconstruction (ACLR). However, injuries to the proximal femoral attachment of the ACL have demonstrated an ability to regenerate. An alternative surgical intervention to the ACLR in this ACL tear subgroup is an ACL repair. The purpose of this case report is to provide a rehabilitation progression for a female gymnast after an ACL repair with Internal Brace Ligament Augmentation (IBLA).

Case Description

The subject was a 16-year-old female who presented with a Sherman Type 1 proximal avulsion of her ACL. She underwent an ACL repair with IBLA. Physical therapy interventions followed a sequential and multi-phased approach based on time for tissue physiologic healing and individual progression. Patient reported outcomes including the International Knee Documentation Committee (IKDC), the Anterior Cruciate Ligament Return to Sport After Injury (ACL-RSI) and the Optimal Screening for Prediction of Referral and Outcome Yellow Flag (OSPRO-YF) were assessed in conjunction with isokinetic strength and hop performance testing to determine return to sport readiness.

Outcomes

The subject completed 42 sessions over the course of 26 weeks in addition to a home exercise program. At return to sport, clinically meaningful improvement was observed in patient reported outcomes including the IKDC, ACL-RSI, and OSPRO-YF. Additionally, strength and hop performance surpassed established thresholds of clinical significance. The subject returned to sport at six months post-operatively.

Conclusion

The subject in this case report returned to full participation in gymnastics six months after an ACL repair with internal bracing following a sequential and multi-phased rehabilitation. The primary ACL repair with IBLA appeared beneficial to this patient and could benefit from additional study in other athletes and athletic populations.

Level of Evidence

Level 5.

Progressive submaximal effort hamstring muscle endurance is reduced after reconstruction of the anterior cruciate ligament

BACKGROUND

Endurance capability in the muscles controlling the knee is poorly understood post anterior cruciate ligament (ACL) reconstruction, despite many sporting activities requiring notable muscle endurance. The hamstring muscles, when active, provide important anatomical support to protect the reconstructed graft. In the absence of good hamstring endurance, fatigue may predispose individuals to re-injury.

OBJECTIVE

To assess whether ACL reconstruction (ACLR) with a hamstring graft leads to reduced hamstring endurance 9-13 months post-surgery.

STUDY DESIGN

A cross-sectional inter-limb comparison study was undertaken with participants 9-13 months after an ACLR with a hamstring graft, and a group of age, sex, and activity-matched controls. There were 22 participants in each group.

METHOD

Submaximal hamstring endurance was measured using a progressive fatigue test on an isokinetic dynamometer at a joint angular velocity of 120°/second. The dependant variable was the maximum number of repetitions performed. Statistical comparisons were made across injured, uninjured and control group limbs.

RESULTS

There was a significant (p < 0.05) deficit in hamstring endurance observed between the injured leg (mean: 111 repetitions, SD 49) and uninjured leg (mean: 136 repetitions, SD 67) of the ACL group, but not between the uninjured and control group legs (mean: 124 repetitions, SD 50).

CONCLUSION

The 18% deficit in submaximal hamstring endurance across the ACL-reconstructed individual's limbs is indicative of a notable loss in muscle performance at 9-13 months post-surgery. These results provide initial evidence for supporting further research examining the inclusion of hamstring endurance training in ACL rehabilitation programmes post-surgery.

Strength symmetry after autograft anterior cruciate ligament reconstruction

OBJECTIVE

To compare postoperative isometric quadriceps strength indices (QI%) and hamstring strength limb symmetry indices (HI%) between partial thickness quadriceps tendon (pQT), full thickness quadriceps tendon (fQT), and bone-patellar-tendon bone (BPTB) autograft anterior cruciate ligament reconstruction (ACLR).

METHODS

Patients with primary ACLR with pQT, fQT, or BPTB autograft with the documentation of quantitative postoperative strength assessments between 2016 and 2021 were included. Isometric Biodex data, including QI% and HI% (calculated as the percentage of involved to uninvolved limb strength) were collected between 5 and 8 months and between 9 and 15 months postoperatively.

RESULTS

In total, 124 and 51 patients had 5-8- and 9-15-month follow-up strength data, respectively. No significant difference was detected between groups for sex. However, patients undergoing fQT were found to be older than those undergoing BPTB (24.6±7 vs 20.2±5; ​p = 0.01). There were no significant differences in the number of concomitant meniscus repairs between the groups (pQT vs. fQT vs. BPTB). No significant differences were detected in median (min-max) QI% between pQT, fQT, and BPTB 5-8 months [87 ​% (44%-130 ​%), 84 ​% (44%-110 ​%), 82 ​% (37%-110 ​%) or 9-15 months [89 ​% (50%-110 ​%), 89 ​% (67%-110 ​%), and 90 ​% (74%-140 ​%)] postoperatively. Similarly, no differences were detected in median HI% between the groups 5-8 months or 9-15 months postoperatively.

CONCLUSION

The study was unable to detect differences in the recovery of quadriceps strength between patients undergoing ACLR with pQT, fQT, and BPTB autografts at 5-8 months and 9-15-months postoperatively.

LEVEL OF EVIDENCE

III.

Adductor longus and brevis lesion in an amateur soccer player: platelet rich plasma and multifractioned hyaluronic acid injections to enhance clinical recovery

Groin pain is a common issue in athletes, with a particularly high incidence in male soccer players. Adductor muscles are the most involved site of the groin, accounting for up to one-fourth of muscle injuries of that region. Physical therapy and rehabilitation programs for adductor-related groin pain using active exercises are effective in getting athletes back to sport. However, the return-to-play time varies according to the injury severity. Minor lesions can recover in 1-2 weeks, while severer injuries require 8-12 weeks. To enhance tendon healing and shorten the return to play time, intrandentinous injections of Platelet Rich Plasma (PRP) have been proposed. An increasing body of evidence in literature have shown efficacy of platelet rich plasma in aiding the healing process in tendinopathies. Similarly, more recent evidences have proven hyaluronic (HA) acid to have anti-inflammatory, proliferative, repairing, and analgesic effects. This case report presents the clinical application of combined PRP and a multifractioned (a mixture of different molecular weights) HA in a 24-year-old athlete suffering from a hip adductor rupture.

Greater self-efficacy, psychological readiness and return to sport amongst paediatric patients compared with adolescents and young adults, 8 and 12 months after ACL reconstruction

PURPOSE

The purpose of this study was to evaluate differences in rehabilitation-specific outcomes between paediatric patients, adolescents and young adults within the first 2 years after anterior cruciate ligament (ACL) reconstruction. A further aim was to determine whether patient age was associated with an increased risk of not achieving symmetrical muscle function within the first 2 years after ACL reconstruction.

METHODS

The patient data in the present study were extracted from the rehabilitation outcome registry, Project ACL. Patients aged 11-25 years registered for primary ACL reconstruction with a hamstring tendon autograft between April 1, 2013 and November 23, 2020 were included. A total of 691 patients met the inclusion criteria and were included in the study; 41 paediatric patients (females 11-13, males 11-15 years), 347 adolescents (females 14-19, males 16-19 years) and 303 young adults (females 20-25, males 20-25 years).

RESULTS

The comparison between groups revealed that 70% of paediatric patients, 39% of adolescents and 35% of young adults had returned to knee-strenuous sport at 8 months and that 90% of paediatric patients, 71% of adolescents and 62% of young adults had returned to sport at 12 months. Paediatric patients also reported higher scores compared with both the other patient groups on the Knee Self-Efficacy Scale (K-SES) and the Anterior Cruciate Ligament Return to Sport after Injury scale (ACL-RSI) at 8 and 12 months.

CONCLUSIONS

A larger proportion of paediatric patients had returned to sport compared with adolescents and young adults 8 and 12 months after ACL reconstruction. Paediatric patients also reported higher self-efficacy and greater psychological readiness to return to sport at 8 and 12 months than the other two groups. No differences in terms of muscle function tests when comparing paediatric patients, adolescents and young adults were found.

LEVEL OF EVIDENCE

II.

Effects of exercise prehabilitation before anterior cruciate ligament reconstruction on functional outcomes during pre- and postoperative rehabilitation - protocol for a single-blinded randomised controlled trial

BACKGROUND

Although a benefit of preoperative training prior to anterior cruciate ligament (ACL) reconstruction is likely, there is no consensus on the optimal content (criteria-based programme), supervision (one-on-one guidance or self-administered training) and general setting of preoperative training after ACL injuries. The purpose of this trial is to investigate the efficacy of an individually adaptive, guided, structured and criteria-based preoperative rehabilitation programme in comparison to a non-guided and self-administered home training programme.

METHODS

The planned single-blinded randomised controlled trial study was approved by the ethics committee of the German Sport University on June 14, 2022 (ethics application no. 093/2022) and prospectively registered (DRKS-ID: DRKS00030312; date of registration: 26.09.2022). N = 114 participants between 16 and 60 years of age with a unilateral ACL rupture and scheduled ACL reconstruction with a hamstring or quadriceps tendon autograft will be randomly (block-randomisation, 1:1 allocation) and blinded assigned to one of two groups: intervention group (structured, criteria-based, guided prehabilitation training) and comparator group (non-guided, self-administered home training). After surgical reconstruction, patients of both groups participate in the same standard, functional measurement-guided, postoperative rehabilitation programme. Stepwise increasing the functional requirements of the assessments, all participants participate in testing at the day of anamnesis (t1), 1-7 days before surgical reconstruction (t2), day of surgical reconstruction (t3) and 30 (t4), 60 (t5), 90 (t6) and 180 (t7) days post-reconstruction. The primary outcome is the overall self-reported knee condition, assessed by the sum score of all sub-scales of the Knee injury and Osteoarthritis Outcome Score (KOOS). Secondary outcomes include functional outcomes (range of motion, knee flexors and extensors and plantar flexors strength/torque, functional postural control, jumping ability), workability and return to sport (RTS) (psychological readiness, RTS success).

DISCUSSION

The planned study targets to fill a gap in the evidence regarding effective designs of prehabilitation training before surgical ACL reconstruction. Potential difficulties that could affect the conduct of the study are lack of treatment adherence of the patients and high dropout.

TRIAL REGISTRATION

German Register of Clinical Trials DRKS-ID: DRKS00030312 . Registered on 26 September 2022.

Are We Jumping to the Wrong Conclusions? Longer Jumps and More Hops in Female Football Players Who Went on to Sustain a Primary or Secondary ACL Injury Compared to Those Who Did Not

BACKGROUND

Different functional performance tests are used to assess patients in the clinic and before return to sport (RTS), where the rehabilitation goal is to reach good strength and jumping ability. A limb symmetry index of ≥ 90% is a common target in rehabilitation before RTS. The aim of this short communication is to use data from our 2-year prospective cohort study on female football players, either with or without an anterior cruciate ligament (ACL) reconstruction, to discuss whether hop performance in 3 commonly used hop tests can inform safe football participation, that is, with a low risk for ACL injury or reinjury.

METHOD

At baseline, 117 active female football players (mean age ± standard deviation, 20 ± 2 years) were included 19 ± 9 months after ACL reconstruction as well as 119 matched female knee-healthy players (age 19 ± 3 years). All players performed a single hop for distance test, 5-jump test and side hop test at baseline and were then prospectively followed for 2 years. Twenty-eight (24%) players sustained a second ACL injury and 8 (7%) sustained a primary ACL injury.

RESULTS

Longer jumps in the 5-jump test (922 cm vs. 865 cm, Cohen's d =  - 0.60) and more hops in the side hop test for both limbs (41-42 hops vs. 33-36 hops, d =  - 0.43 to - 0.60) were seen in players who sustained a second ACL injury compared with those who did not. Longer jumps in the single hop for distance test (both limbs) (139-140 cm vs. 124-125 cm, d =  - 0.38 to - 0.44), in the 5-jump test (975 cm vs. 903 cm, d = -0.42) and more hops in the side hop test (both limbs) (48-49 hops vs. 37-38 hops, d =  - 0.38 to - 0.47) were seen in players who sustained a primary ACL injury compared with those who did not.

CONCLUSIONS

The average hop performance, i.e. longer jumps or more hops, was greater in players who went on to sustain a primary or secondary ACL injury compared to those who did not over a two-year follow-up period. Even though hop tests are not used in isolation to evaluate readiness to RTS, their interpretation needs consideration in the decision-making process of returning to pivoting sports.

Assessment of Return to Sport After ACL Reconstruction With Soft Tissue Autograft in Adolescent Athletes: Quadriceps Versus Hamstring Tendon

Background

Quadriceps tendon soft tissue autograft represents an increasingly popular graft option for anterior cruciate ligament reconstruction (ACLR), particularly for adolescents, some of whom have an open physis, precluding use of graft options with bone plugs.

Purpose/Hypothesis

The purpose of this study was to quantify return-to-sport performance assessments in adolescents at 6 months after ACLR with all-soft tissue quadriceps tendon autograft (ACLR-Q) versus hamstring tendon autograft (ACLR-HS). It was hypothesized that ACLR-Q would be associated with improved hamstring strength and hamstring-to-quadriceps (HS:Q) ratios compared with ACLR-HS, albeit with decreased quadriceps strength.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Included were patients aged 12 to 19 years who underwent primary ACLR by a single surgeon and who completed a return-to-sport performance assessment between 5 and 9 months postoperatively. The performance assessment included manual muscle strength tests (hamstring, quadriceps, hip abductor and adductor), dynamic balance test (Y-balance), and functional hop tests (single hop, triple hop, crossover hop, 6-m timed hop). Data were converted to limb symmetry indices, and limb symmetry index deficits were compared between the ACLR-Q and ACLR-HS cohorts using the Student t test or Wilcoxon-Mann-Whitney test.

Results

An initial cohort of 90 ACLR-Q patients was compared with 54 ACLR-HS patients, with no significant differences in patient characteristics. Differences in meniscal repair rates, however, prompted use of propensity score matching on age, sex, body mass index, meniscectomy, and meniscal repair to produce comparable subcohorts. The matching resulted in 67 ACLR-Q and 52 ACLR-HS patients. Hamstring strength deficits were significantly greater in ACLR-HS versus ACLR-Q patients (-40.5% vs -5.7%; P < .001). Quadriceps strength deficits were significantly greater in ACLR-Q versus ACLR-HS patients (-12.8% vs -0.4%; P < .001). ACLR-Q patients had a significantly greater HS:Q ratio on the operative knee (P < .001) and significantly higher Y-balance composite score deficits (-2.9% vs -0.4%; P = .01) than ACLR-HS patients. There were no significant differences in hop test performance between groups.

Conclusion

Adolescent athletes who underwent ACLR-Q showed significantly greater quadriceps strength deficits but significantly smaller hamstring strength deficits than those who underwent ACLR-HS, leading to more favorable HS:Q ratios in ACLR-Q patients at 6 months postoperatively.

Reconsideration of Return-to-Sport Decision-Making After Pediatric ACL Injury: A Scoping Review

CONTEXT

Up to 90% of pediatric athletes return to sport (RTS) after anterior cruciate ligament reconstruction (ACL-R); however, <50% RTS at the same level and second ACL injury rates are up to 32%.

OBJECTIVES

(1) Determine which physical and patient-reported outcome measures guide clinical decision-making on RTS in pediatric athletes after ACL-R and (2) present a framework with insights from cognitive and neurophysiological domains to enhance rehabilitation outcomes.

DATA SOURCES

PubMed, CINAHL, Embrase, and Cochrane library databases and gray literature.

STUDY SELECTION

Data on pediatric (<18 years) ACL-R patients, RTS, tests, and decision-making were reported in 1214 studies. Two authors independently reviewed titles and abstract, excluding 962 studies. Gray literature and cross-reference checking resulted in 7 extra studies for full-text screening of 259 studies. Final data extraction was from 63 eligible studies.

STUDY DESIGN

Scoping review.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Details on study population, aims, methodology, intervention, outcome measures, and important results were collected in a data chart.

RESULTS

Studies included 4456 patients (mean age, 14 years). Quadriceps and hamstring strength (n = 25), knee ligament arthrometer (n = 24), and hop tests (n = 22) were the most-reported physical outcome measures guiding RTS in <30% of studies with cutoff scores of limb symmetry index (LSI) ≥85% or arthrometer difference <3 mm. There were 19 different patient-reported outcome measures, most often reporting the International Knee Documentation Committee (IKDC) (n = 24), Lysholm (n = 23), and Tegner (n = 15) scales. Only for the IKDC was a cutoff value of 85% reported.

CONCLUSION

RTS clearance in pediatric ACL-R patients is not based on clear criteria. If RTS tests were performed, outcomes did not influence time of RTS. Postoperative LSI thresholds likely overestimate knee function since biomechanics are impaired despite achieving RTS criteria. RTS should be considered a continuum, and biomechanical parameters and contextual rehab should be pursued with attention to the individual, task, and environment. There is a need for psychological monitoring of the ACL-R pediatric population.

The MyJump App is a Valid Method of Assessing and Classifying Limb Symmetry During Recovery from Anterior Cruciate Ligament Reconstruction

Background

Jump testing performance and limb symmetry measures are important metrics for clinicians to monitor during rehabilitation after Anterior Cruciate Ligament (ACL) reconstruction, however they require hardware and software which is not commonly available in clinical practice. Video-based solutions may present a feasible alternative, but their veracity in classifying patients using limb-symmetry of 90% has not been established, nor have the clinimetric values for the performance measures been reported in this population.

Purpose

To describe the diagnostic accuracy (pass/fail using 90% LSI) and clinimetrics of an iPad-based app ("MyJump") compared to reference force plate analyses for limb symmetry, jump/hop height, contact time, flight time, and reactive strength index.

Study design

Prospective cohort, diagnostic accuracy.

Methods

Fifty-one consecutive patients recovering from ACL reconstruction undertaking routine independent clinical evaluation of their hop and jump performance were concurrently and independently examined using force plates and the MyJump app. Diagnostic accuracy of MyJump was compared to reference force plate analyses using a criterion of 90% limb symmetry.

Results

Diagnostic accuracy of the MyJump app was very good: positive predictive value for jump height was 0.83 and 1.0 for reactive strength index, and negative predictive value was 0.95 and 1.0 for the same metrics, respectively. Of the 131 classifications made using the MyJump app, there were five false positives and three false negatives - all of these were in classification of jump height with no misclassifications of RSI. Irrespective of jump type, the MyJump app displayed excellent reliability (ICC>0.95) for both height and reactive strength index. Minimum detectable changes were approximately 1cm for height, 0.1 for reactive strength index, 0.02s for contact time, and 0.3s for flight time.

Conclusion

Where force plates are unavailable, the MyJump app is a valid and reliable substitute for criteria assessment of jump/hop height and reactive strength index in those recovering from ACL surgery using a 90% limb symmetry threshold. The minimum detectable changes vary by metric but are likely sufficiently accurate to detect clinical changes.

Level Of Evidence

Level 3.

Factors Associated With Sports Function and Psychological Readiness to Return to Sports at 12 Months After Anterior Cruciate Ligament Reconstruction: A Cross-sectional Study

BACKGROUND

Sports function and psychological readiness to return to sports (RTS) are important outcomes when evaluating rehabilitation after anterior cruciate ligament reconstruction (ACLR). It is, however, unclear which specific factors contribute most to these outcomes.

PURPOSE

To determine associations between demographic characteristics, objective measurements of physical function, patient-reported outcome measure scores, sports-related function assessed with the Knee injury and Osteoarthritis Outcome Score (KOOS) Sport and Recreation subscale, and psychological readiness to RTS assessed with the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale at 1 year after ACLR.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

At a mean of 12.5 ± 2.0 months after ACLR, 143 participants (50.3% female), with a mean age of 25.0 ± 5.7 years, were assessed for demographic characteristics, physical factors (hop performance, muscle strength, ankle and hip range of motion), and psychological factors (KOOS Pain and Symptoms subscales, Perceived Stress Scale, fear of reinjury) as well as the KOOS Sport and Recreation subscale and ACL-RSI scale. Backward linear regression models were used to evaluate factors associated with sports function and psychological readiness to RTS.

RESULTS

Lower isokinetic knee extension peak torque (limb symmetry index) (B = 18.38 [95% CI, 3.01-33.75]), lower preinjury activity level (B = 2.00 [95% CI, 0.87-3.14]), greater knee pain (B = 0.90 [95% CI, 0.70-1.10]), shorter time between injury and reconstruction (B = 0.16 [95% CI, 0.05-0.26]), and greater fear of reinjury (B = 0.11 [95% CI, 0.01-0.20]) were associated with a worse KOOS Sport and Recreation subscore (R2 = 0.683). A shorter hop distance (B = 0.15 [95% CI, 0.00-0.29]) was associated with a lower ACL-RSI score (R2 = 0.245).

CONCLUSION

A combination of knee muscle strength, activity level, knee pain, timing of surgery, and fear of reinjury accounted for approximately 70% of the variation in sports function at 1 year after ACLR. In contrast, there was only 1 weak association between physical function and psychological readiness to RTS at this time point. Thus, factors associated with current sports function are much better known than features related to psychological readiness to RTS.

Comparison between the effect of immersive virtual reality training versus conventional rehabilitation on limb loading and functional outcomes in patients after anterior cruciate ligament reconstruction: A prospective randomized controlled trial

Purpose

Anterior cruciate ligament injury (ACL) commonly occurs during sporting events. It causes pain, instability and reduction in range of movement of the knee which results in altered balance, reduced strength as well as loading to the involved knee. The challenge to get the patient back to competitive sports level much depends on the rehabilitation process. Post ACLR rehabilitation is challenging due to the long rehabilitation time as well as boring repetitive exercises. The aim of this study is to compare between the effectiveness of using immersive virtual reality (PlayStation VR) in addition to the conventional rehabilitation as an aid in rehabilitation of patients after ACLR in terms of objective functional assessment and pain and subjective knee function scoring.

Methods

This randomised controlled trial was undertaken in a tertiary hospital in Malaysia from July 2019 until July 2020. Thirty patients were randomised into a group undergoing purely conventional rehabilitation (Group 1) and a group undergoing both conventional rehabilitation and immersive virtual reality assisted rehabilitation (Group 2). The immersive virtual reality assisted rehabilitation was started at 3 months post operatively for 3 months duration. Limb loading, balance, range of motion, functional hop tests of the knee, pain and subjective scoring of the knee with the International Knee Documentation Committee (IKDC) Scores were measured preoperatively and at 6 months.

Results

There were significant differences in terms of improvement of pain scores (p = 0.012) as well as IKDC Scores (p = 0.024) in Group 2 as compared to Group 1. However, there were no significant differences with regards to limb loading, balance, range of motion and functional hop tests of the knee (p > 0.05). No adverse events were observed during the study period.

Conclusion

Immersive virtual reality can be used as an adjunct in rehabilitation of patients after ACL reconstruction in terms of improving their pain as well as their subjective knee evaluation. Large randomised control trial is recommended to further investigate the efficacy.

Patients with unilateral ankle arthritis have decreased discrete and time-series limb symmetry compared to healthy controls

Patients with ankle arthritis (AA) have side-to-side limb differences at the ankle and in spatiotemporal measures; however, the degree of symmetry between limbs has not been compared to a healthy population. The purpose of this study was to determine differences in limb symmetry during walking for discrete and time-series measures when comparing patients with unilateral AA to healthy participants. Thirty-seven AA and 37 healthy participants were age, gender, and body mass index matched. Three-dimensional gait mechanics and ground reaction force (GRF) were captured during four to seven walking trails. GRF and hip and ankle mechanics were extracted bilaterally for each trial. The Normalized Symmetry Index and Statistical Parameter Mapping were used to assess discrete and time-series symmetry, respectively. Discrete symmetry was analyzed using linear mixed-effect models to determine significant differences between groups (α = 0.05). Compared to healthy participants, patients with AA had decreased weight acceptance (p = 0.017) and propulsive (p < 0.001) GRF, ankle plantarflexion (p = 0.021), ankle dorsiflexion (p = 0.010), and ankle plantarflexion moment (p < 0.001) symmetry. Significant regions of difference were found between limbs and groups throughout the stance phase for the vertical GRF force (p < 0.001), the ankle angle during push-off (p = 0.047), the plantarflexion moment (p < 0.001), and the hip extension angle (p = 0.034) and moment (p = 0.010). Patients with AA have decreased symmetry in the vertical GRF and at the ankle and hip during the weight acceptance and propulsive portions of the stance phase. Therefore, clinicians should try a non improving symmetry focusing on changing hip and ankle mechanics during the weight acceptance and propulsive phases of gait.

No Effect of Return to Sport Test Batteries with and without Psychological PROs on the Risk of a Second ACL Injury: A Critical Assessment of Four Different Test Batteries

Background

Patients report psychological barriers as important when returning to sport, however, psychological outcome measures are seldom included in return to sport (RTS) assessment. There is a need for clinical trials to integrate psychological patient-reported outcomes (PROs) in return to sport batteries assessing patients treated with ACL reconstruction.

Objective

The aim of this study was to determine the association between passing clinical tests of muscle function and psychological PROs and sustaining a second ACL injury in patients who RTS after primary ACL reconstruction.

Design

Retrospective Cohort study.

Methods

Patients' sex, age, height and weight, and the results of strength and hop tests, as well as answers to PRO's (including Tegner activity scale, the ACL Return to Sport after Injury scale (ACL-RSI) as well as the Quality of Life (QoL) subscale of the Knee injury and Osteoarthritis Outcome Score [KOOS]), were extracted from a rehabilitation-specific registry. Four different test batteries comprising muscle function tests and PROs were created to assess whether patients were ready to RTS. Passing each of the test batteries (yes/no) was used as an independent variable. A multivariable Cox proportional hazard model analysis was performed, with sustaining a second ACL injury (either ipsi- or contralateral; yes/no) within two years of RTS as the dependent variable.

Results

A total of 419 patients (male, n=214; 51%) were included, of which 51 (12.2%) suffered a second ACL injury within the first two years after RTS. There were no differences in passing rates in the different RTS test batteries comprising muscle function tests and PROs for patients who suffered a second ACL injury compared to patients who did not.

Conclusion

No association between passing the RTS clinical tests batteries comprising muscle function and psychological PROs used, and the risk of a second ACL injury could be found.

Level of Evidence

3©The Author(s).

Single-Legged Triple-Hop Propulsion Strategies in Females With and Those Without a History of Anterior Cruciate Ligament Reconstruction

CONTEXT

The single-legged triple hop is a commonly used functional task after anterior cruciate ligament reconstruction (ACLR). Recently, researchers have suggested that individuals may use a compensatory propulsion strategy to mask underlying quadriceps dysfunction and achieve symmetric hop performance.

OBJECTIVE

To evaluate the performance and propulsion strategies used by females with and those without ACLR during a single-legged triple hop.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 38 females, 19 with ACLR (age = 19.21 ± 1.81 years, height = 1.64 ± 0.70 m, mass = 63.79 ± 7.59 kg) and 19 without ACLR (control group; age = 21.11 ± 3.28 years, height = 1.67 ± 0.73 m, mass = 67.28 ± 9.25 kg).

MAIN OUTCOME MEASURE(S)

Hop distance and limb symmetry index (LSI) were assessed during a single-legged triple hop for distance. Propulsion strategies were evaluated during the first and second hops of the single-legged triple hop. Separate 2-way analysis-of-variance models were used to examine the influence of ACLR, joint, and their interaction on mechanical joint work, moment impulse, and the relative joint contributions to total work and moment impulse in females with and those without a history of ACLR.

RESULTS

Despite achieving a mean LSI of approximately 96%, the ACLR group produced less total work in the reconstructed than the uninvolved limb during single-legged triple-hop propulsion (first hop: t18 = -3.73, P = .002; second hop: t18 = -2.55, P = .02). During the first and second hops, the reconstructed knee generated 19.3% (t18 = -2.33, P = .03) and 27.3% (t18 = -4.47, P < .001) less work than the uninvolved knee. No differences were identified between the involved and uninvolved limbs of the ACLR group in moment impulse (first hop: t18 = -0.44, P = .67; second hop: t18 = -0.32; P = .76). Irrespective of limb or group, the ankle was the largest contributor to both work and moment during both the first and second hops (P < .001).

CONCLUSIONS

Clinicians should exercise caution when using a single-legged triple hop as a surrogate for restored lower extremity function in females post-ACLR. This recommendation is driven by the compelling findings that knee-joint deficits persisted in the reconstructed limb despite an LSI of approximately 96% and, regardless of previous injury status, single-legged triple-hop propulsion was predominantly driven by the ankle.

Recurrence quantification analysis of isokinetic strength tests: A comparison of the anterior cruciate ligament reconstructed and the uninjured limb

BACKGROUND

Despite widespread use of return to sport testing following anterior cruciate ligament reconstruction, studies suggest inadequacy in current testing criteria, such as limb symmetry index calculations, to determine athletes' readiness to return to play. Recurrence quantification analysis, an emerging non-linear data analysis tool, may reveal subtle neuromuscular differences between the injured and uninjured limb that are not captured by traditional testing. We hypothesized that isokinetic torque curve data of the injured limb would demonstrate lower determinism and entropy as compared to the uninjured limb.

METHODS

102 patients (44 M, 58F, 10 ± 1 months post-anterior cruciate ligament reconstruction) underwent isokinetic quadriceps strength testing using a HumacNorm dynamometer. Patients completed maximum effort knee extension and flexion at 60°/sec. Data were post-processed with a MATLAB CRQA Graphical User Interface and determinism and entropy values were extracted. Paired-sample t-tests (α = 0.05) were used to compare data from the injured and uninjured limb.

FINDINGS

Determinism and entropy values in the torque curves were lower in the injured limb than the uninjured limb (p < 0.001). Our findings indicate there is less predictability and complexity present in the torque signals of injured limbs.

INTERPRETATION

Recurrence quantification analysis can be used to assess neuromuscular differences between limbs in patients who have undergone anterior cruciate ligament reconstruction. Our findings offer further evidence that there are changes to the neuromuscular system which persist following reconstruction. Further investigation is needed to establish thresholds of determinism and entropy values needed for safe return to sport and to evaluate the utility of recurrence quantification analysis as a return to sport criterion.

Single-Legged Triple-Hop Propulsion Strategies in Females With and Those Without a History of Anterior Cruciate Ligament Reconstruction

CONTEXT

The single-legged triple hop is a commonly used functional task after anterior cruciate ligament reconstruction (ACLR). Recently, researchers have suggested that individuals may use a compensatory propulsion strategy to mask underlying quadriceps dysfunction and achieve symmetric hop performance.

OBJECTIVE

To evaluate the performance and propulsion strategies used by females with and those without ACLR during a single-legged triple hop.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 38 females, 19 with ACLR (age = 19.21 ± 1.81 years, height = 1.64 ± 0.70 m, mass = 63.79 ± 7.59 kg) and 19 without ACLR (control group; age = 21.11 ± 3.28 years, height = 1.67 ± 0.73 m, mass = 67.28 ± 9.25 kg).

MAIN OUTCOME MEASURE(S)

Hop distance and limb symmetry index (LSI) were assessed during a single-legged triple hop for distance. Propulsion strategies were evaluated during the first and second hops of the single-legged triple hop. Separate 2-way analysis-of-variance models were used to examine the influence of ACLR, joint, and their interaction on mechanical joint work, moment impulse, and the relative joint contributions to total work and moment impulse in females with and those without a history of ACLR.

RESULTS

Despite achieving a mean LSI of approximately 96%, the ACLR group produced less total work in the reconstructed than the uninvolved limb during single-legged triple-hop propulsion (first hop: t18 = -3.73, P = .002; second hop: t18 = -2.55, P = .02). During the first and second hops, the reconstructed knee generated 19.3% (t18 = -2.33, P = .03) and 27.3% (t18 = -4.47, P < .001) less work than the uninvolved knee. No differences were identified between the involved and uninvolved limbs of the ACLR group in moment impulse (first hop: t18 = -0.44, P = .67; second hop: t18 = -0.32; P = .76). Irrespective of limb or group, the ankle was the largest contributor to both work and moment during both the first and second hops (P < .001).

CONCLUSIONS

Clinicians should exercise caution when using a single-legged triple hop as a surrogate for restored lower extremity function in females post-ACLR. This recommendation is driven by the compelling findings that knee-joint deficits persisted in the reconstructed limb despite an LSI of approximately 96% and, regardless of previous injury status, single-legged triple-hop propulsion was predominantly driven by the ankle.

The effects of different rehabilitation training modalities on isokinetic muscle function and male athletes' psychological status after anterior cruciate ligament reconstructions

BACKGROUND

Previously, researchers reported performance enhancements following long-term plyometric training in athletes with anterior cruciate ligament reconstruction (LCA). However, the effects of combined eccentric and plyometric training on measures of isokinetic strength and psychological statues in male athletes have not been examined yet. Knowledge on the effects of combined eccentric and plyometric training help to better plan and program rehabilitations sessions and thus return-to-sports.

OBJECTIVE

This study sought to compare the effects of three different rehabilitation training programs, eccentric training (ECC), plyometric training (PLYO), or combined eccentric and plyometric training (COMB), on psychological measures (kinesiophobia [TSK-CF], functional knee assessment, knee injury and osteoarthritis outcome score [KOOS], international knee documentation committee 2000 questionnaire [IKDC], and knee flexor and extensor isokinetic muscle performance (peak torque [PT], total work, ratio [R-HQ], and ratio of total work [R-TW]) at different angular velocities post ACL surgery in male elite athletes.

METHODS

Forty elite male athletes from different sports (e.g., athletics, team sports) with ACL reconstruction participated in this study. The study started after a 14-weeks post-surgery rehabilitation program, which was identical for all subjects. After this initial rehabilitation period, athletes were randomly assigned to three experimental groups, ECC (n = 10), PLYO (n = 10), and COMB (n = 10), and a control group (CON: n = 10). Testing was conducted pre- and post-the 6-weeks intervention period and included the TSK-CF, KOOS, and IKDC. Peak torque of the knee extensors/flexors was tested at 90, 180, 240 °/s, after the 6-weeks training program only.

RESULTS

Participants' adherence rate was 100% across all groups and none reported any training or test-related injury. No significant between-group baseline differences (pre-6-weeks intervention) were observed for any of the reported psychological and muscle strength parameters. Significant group-by-time interactions were found for TSK-CF (p = 0.001, d = 2.85), KOOS (p = 0.001, d = 1.31), and IKDC (p = 0.001, d = 1.07). The post-hoc analyses indicated that COMB showed larger pre-post improvements for all psychological variables (p < 0.001, d = 2.95 to 13.15), compared with PLYO, ECC, and CON. Contrast analyses demonstrated that COMB yielded significantly greater improvements compared with CON, PLYO, ECC for all isokinetic parameters at all three angular velocities (all p < 0.001, d = 0.99 to 4.61).

CONCLUSION

The results showed that COMB induced greater gains for measures of psychological status and isokinetic muscle strength compared with single-mode PLYO and ECC in elite male athletes during a post-surgery ACL rehabilitation period. Accordingly, it is recommended to implement COMB as an effective rehabilitation means to improve knee function in male elite athletes.

TRIAL REGISTRATION

This study does not report results related to health care interventions using human participants and therefore it was not prospectively registered.

A scoping review of portable sensing for out-of-lab anterior cruciate ligament injury prevention and rehabilitation

Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) surgery are common. Laboratory-based biomechanical assessment can evaluate ACL injury risk and rehabilitation progress after ACLR; however, lab-based measurements are expensive and inaccessible to most people. Portable sensors such as wearables and cameras can be deployed during sporting activities, in clinics, and in patient homes. Although many portable sensing approaches have demonstrated promising results during various assessments related to ACL injury, they have not yet been widely adopted as tools for out-of-lab assessment. The purpose of this review is to summarize research on out-of-lab portable sensing applied to ACL and ACLR and offer our perspectives on new opportunities for future research and development. We identified 49 original research articles on out-of-lab ACL-related assessment; the most common sensing modalities were inertial measurement units, depth cameras, and RGB cameras. The studies combined portable sensors with direct feature extraction, physics-based modeling, or machine learning to estimate a range of biomechanical parameters (e.g., knee kinematics and kinetics) during jump-landing tasks, cutting, squats, and gait. Many of the reviewed studies depict proof-of-concept methods for potential future clinical applications including ACL injury risk screening, injury prevention training, and rehabilitation assessment. By synthesizing these results, we describe important opportunities that exist for clinical validation of existing approaches, using sophisticated modeling techniques, standardization of data collection, and creation of large benchmark datasets. If successful, these advances will enable widespread use of portable-sensing approaches to identify ACL injury risk factors, mitigate high-risk movements prior to injury, and optimize rehabilitation paradigms.

Drop Jump Performance Improves One Year Following Anterior Cruciate Ligament Reconstruction in Sportsmen Irrespectively of Psychological Patient Reported Outcomes

Our study aims to prospectively report the functional outcomes of 31 sportsmen following anterior cruciate ligament (ACL) reconstruction, up to 12 months after surgery, with regards to subjective tests and drop jump performance, and to investigate the correlations between these variables, to be used for determining the return to sports after ACL reconstruction. Lysholm score, Tegner activity level, and the ACL-Return to Sport after Injury (ACL-RSI) scale were evaluated preoperatively, at 6 months, and at 12 months after surgery. Drop vertical jump was recorded using an infrared optical acquisition system. Lysholm and ACL-RSI scores significantly improved at the 12-month follow-up compared to the baseline and 6-month evaluations (p < 0.001). Concerning Tegner activity level, no statistically significant differences were reported between pre- and post-operative status (p = 0.179). Drop jump limb symmetry index significantly improved at 12 months, with the mean value improving from 76.6% (SD: 32,4) pre-operatively to 90.2% (SD: 14.7; p < 0.001) at follow-up. Scarce positive correlation was reported between the ability to perform drop jumps and activity level in athletes one year after ACL reconstruction. In addition, subjective knee score and psychological readiness were not related to jumping performance.