Differential influence of quadriceps rate of torque development on single- and double-leg landing mechanics in anterior cruciate ligament reconstructed and control females

PURPOSE

The capacity to explosively contract quadriceps within the critical timeframe associated with anterior cruciate ligament (ACL) injury, quantified by the rate of torque development, is potentially essential for safe landing mechanics. This study aimed to investigate the influence of explosive quadriceps strength on ACL-related sagittal-plane landing mechanics in females with and without ACL reconstruction (ACLR).

METHODS

Quadriceps explosive strength and landing mechanics were assessed in 19 ACLR and 19 control females during isometric contractions and double- and single-leg jump landings. A stepwise multiple linear regression model determined the variance in each of the landing biomechanics variables for the ACLR limb and nondominant limb of controls that could be explained by the group, rate of torque development and/or their interaction. If peak kinetic variables could be predicted by the rate of torque development or interaction, additional analyses were conducted, accounting for knee flexion as a covariate in the regression model.

RESULTS

During single-leg landings, ACLR females exhibited greater knee flexion at initial contact than controls (p = 0.04). Greater quadriceps rate of torque development predicted higher peak posterior ground reaction force and anterior tibial shear force in both groups (p = 0.04). However, after controlling for knee flexion angle at those peak forces, quadriceps rate of torque development was not predictive. In double-leg landings, greater explosive quadriceps strength was associated with quicker attainment of peak knee extension moment and posterior ground reaction force in the ACLR limb (p = 0.03).

CONCLUSION

Regardless of ACL injury status, females with greater explosive quadriceps strength adopted safer single-leg landings through increased knee flexion, potentially mitigating ACL loading despite encountering higher peak forces. During double-leg landings, a greater explosive quadriceps strength of the ACLR limb is associated with faster achievement of peak force upon landing. Incorporating explosive quadriceps strengthening into post-ACLR rehabilitation and injury prevention programmes may enhance landing mechanics for reducing primary and subsequent ACL injury risks.

LEVEL OF EVIDENCE

Level II.

Return to badminton play following an ACL injury is common, but only a few return to previous performance

PURPOSE

To report how many badminton players return to badminton after an anterior cruciate ligament (ACL) injury and to which level.

METHODS

Patients in Denmark from 2000 to 2018, registered in the Danish National Patient Register with a diagnosis of ACL rupture and badminton as a primary sport were asked about a return to sport (RTS) and return to performance (RTP) after ACL injury. RTP was defined as the return to full participation in the same sport, same level and same preinjury performance. To investigate the likelihood of RTS and return to preinjury level, a binominal logistic regression was used.

RESULTS

Badminton was the primary sport for 900 participants. Only 435 players were injured during badminton, and 626 participants intended to RTP. RTS was achieved by 396 (63%) and 117 (19%) returned to the same performance as their preinjury level. However, 273 (44%) returned to full participation at the same level as the preinjury level but did not perform as well. Males had a significantly higher RTS than females, and RTP was also higher among males [221 (68%) vs. 175 (58%), odds ratio, OR: 1.67, p = 0.003 and 74 (23%) vs. 43 (14%), OR: 1.58, p = 0.05].

CONCLUSION

Return to badminton was achieved by 396 (63%), but only 117 (19%) returned to the same performance as their preinjury level after ACL injury. Females are less successful in RTS and RTP. Future research on improving RTS and the RTP rates in badminton, in general, and specifically for females is needed.

LEVEL OF EVIDENCE

Level II.

Gender differences in the impact of anatomical factors on non-contact anterior cruciate ligament injuries: a magnetic resonance study

PURPOSE

To identify MRI-detected anatomical risk factors for non-contact anterior cruciate ligament (ACL) injuries across genders.

METHODS

A retrospective analysis was performed on 141 ACL-reconstructed patients (35 females, 106 males) and 142 controls (37 females, 105 males) from January 2020 to April 2022. Inclusion criteria were primary non-contact ACL injuries. The tibial plateau slope, lateral femoral condyle index, Insall-Salvati index, and patellar tendon angle were measured, using binary logistic regression for gender-specific risk evaluation.

RESULTS

Increased lateral tibial plateau slope, reduced intercondylar notch width index, lateral femoral condyle index, and patellar tendon angle correlated with ACL injuries in both genders. The Insall-Salvati index was a significant risk factor in females but not in males.

CONCLUSION

This study identifies the lateral tibial plateau slope, notch width index, lateral femoral condyle index, and patellar tendon angle at near-extension as risk factors for ACL injuries in both genders, with the Insall-Salvati index also implicated in females.

Spatiotemporal lower-limb asymmetries during stair descent in athletes following anterior cruciate ligament reconstruction

PURPOSE

This study evaluated motor control recovery at different times following anterior cruciate ligament reconstruction (ACLR) by investigating lower-limb spatiotemporal symmetry during stair descent performances.

METHODS

We used a cross-sectional design to compare asymptomatic athletes (Controls, n = 18) with a group of people with ACLR (n = 49) divided into three time-from-ACLR subgroups (Early: <6 months, n = 17; Mid: 6-18 months, n = 16; Late: ≥18 months, n = 16). We evaluated: "temporal symmetry" during the stance subphases (single-support, first and second double-support) and "spatial symmetry" for hip-knee-ankle intra-joint angular displacements during the stance phase using a dissimilarity index applied on superimposed 3D phase plots.

RESULTS

We found significant between-group differences in temporal variables (p ≤ 0.001). Compared to Controls, both Early and Mid (p ≤ 0.05) showed asymmetry in the first double-support time (longer for their injured vs. non-injured leg), while Early generally also showed longer durations in all other phases, regardless of stepping leg. No statistically significant differences were found for spatial intra-joint symmetry between groups.

CONCLUSION

Temporal but not spatial asymmetry in stair descent is often present early after ACLR; it may remain for up to 18 months and may underlie subtle intra- and inter-joint compensations. Spatial asymmetry may need further exploration.

ACL Reconstruction using Achilles Allograft in a Case of Genu Recurvatum with Supracondylar Osteotomy

Introduction

People with post-polio syndrome usually have some residual deformities. Genu recurvatum is very commonly seen in such cases which are a risk factor for anterior cruciate ligament (ACL) injury due to the altered biomechanics. To the best of our knowledge, this is the first report in literature presenting ACL reconstruction in a limb with genu recurvatum deformity treated with supracondylar osteotomy.

Case Report

A 49-year-old female with genu recurvatum and history of polio presented with pain and instability. Staged procedure of supracondylar osteotomy and ACL reconstruction Achilles allograft was done.

Conclusion

ACL tears in a poliotic limb with genu recurvatum deformity can be a challenging case. Precise pre-operative preparation can aid in managing the case successfully.

Tibial spine volume is smaller in ACL-injured athletes compared to healthy athletes

PURPOSE

The aim of this study was to investigate whether the whole tibial spine volume and femoral intercondylar notch volume are risk factors for anterior cruciate ligament (ACL) injury. The hypothesis was that the whole tibial spine volume and femoral notch volume would be smaller in athletes who sustained ACL injury than in athletes with no history of ACL injury.

METHODS

Computed tomography scans of both knees were acquired and three-dimensional bone models were created using Mimics to measure whole tibial spine volume and femoral notch volume. Tibial spine volume, femoral notch volume and each of these volumes normalised by tibial plateau area were compared between the ACL-injured and the ACL-intact group.

RESULTS

Fifty-one athletes undergoing unilateral anatomical ACL reconstruction (17 female, 34 male: average age 22.0 ± 7.5) and 19 healthy collegiate athletes with no previous knee injury (eight female, 11 male: average age 20.1 ± 1.3) were included in this study. The whole tibial spine volume in the ACL-injured group (2.1 ± 0.5 cm3) was 20.7% smaller than in the ACL-intact group (2.7 ± 0.7 cm3) (p = 0.005). No differences were observed between the femoral notch volume in the ACL-injured group (9.5 ± 2.1 cm3) and the ACL-intact group (8.7 ± 2.7 cm3) (n.s.).

CONCLUSIONS

The main finding of this study was that the whole tibial spine volume of the ACL-injured group was smaller than the ACL-intact group. A small tibial spine volume can be added to the list of anatomical risk factors that may predispose athletes to ACL injury.

LEVEL OF EVIDENCE

Level Ⅲ.

Test-retest reliability and concurrent validity assessment of a novel high-frequency sensor device for anterior tibial translation measurement in loaded and unloaded condition: an exploratory cross-sectional study

BACKGROUND

Magnetic resonance imaging (MRI) and manual tests remain the standard for diagnosing anterior cruciate ligament (ACL) rupture. Furthermore, the passive knee displacement, also described as anterior tibial translation (ATT), is used in order to make decisions about surgery or to assess rehabilitation outcomes. Unfortunately, these manual tests are limited to passive situations, and their application to assess knee stability in loaded, weight-bearing positions are missing. Therefore, a new device with high-performance sensors and a new sensor setting was developed. The aim of this exploratory cross-sectional study was to assess the test-retest reliability of this new device in a first step and the concurrent validity in a second step.

METHODS

A total of 20 healthy volunteers were measured. Measurement consistency of the new device was assessed on the basis of reliability during Lachman test setting and in loaded position by artificial knee perturbation in a test-retest procedure. In a second step, the concurrent validity was evaluated with the Lachmeter® as a reference instrument. Intraclass correlation coefficient (ICC), standard error of measurement (SEM), the minimal detectable change (MDC) and Bland-Altman analysis were evaluated to assess the quality criteria.

RESULTS

The measurements with the new device during the Lachman test provided a mean ATT of 5.46±2.22mm. The SEM ranged from 0.60 to 0.69mm resulting in an MDC between 1.67 and 1.93mm for the new device. In the loaded test situation, the mean ATT was 2.11±1.20mm, with test-retest reliability also showing good correlation (r>0.83). The comparison of the two measurement methods with an ICC of (r>0.89) showed good correlation, which also underlines the reasonable agreement of the Bland-Altman analysis.

CONCLUSIONS

The evaluation of the test-retest reliability of the new device during the knee stability testing in passive situation as well as in a functional, loaded situation presented good reliability. In addition, the new device demonstrated good agreement with the reference device and therefore good validity. Furthermore, the quality criteria demonstrated the ability of the new device to detect the cut-off value (3-5mm) described in the literature for the diagnosis of ACL-deficient knees, which underlines the clinical relevance of this new device as a reliable and valid tool.

Video Analysis of Anterior Cruciate Ligament Injuries in Male Professional Basketball Players: Injury Mechanisms, Situational Patterns, and Biomechanics

Background

Improving our understanding of the situations and biomechanics that result in an anterior cruciate ligament (ACL) injury in basketball players may support the design of more effective programs to mitigate the risk of injury.

Purpose

To (1) describe the mechanisms, situational patterns, and gross biomechanics (kinematics) of ACL injuries in professional basketball matches using video analysis and (2) document the distribution of ACL injuries according to player position, phase of the match, and location on the court.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 38 ACL injuries in professional male European basketball leagues from the 2013-2014 to 2019-2020 seasons were identified. There were 36 (95%) injury videos analyzed for injury mechanisms and situational patterns, while biomechanical analysis was possible in 32 cases. Overall, 3 independent reviewers evaluated each video. Data according to player position (n = 38), phase of the match (n = 38), and location on the court (n = 36) were evaluated.

Results

More injuries occurred while attacking (n = 25 [69%]) than defending (n = 11 [31%]). There was 1 (3%) direct contact injury, 21 (58%) indirect contact injuries, and 14 (39%) noncontact injuries. Most injuries (83%) occurred during 3 main situations: offensive cut (n = 17 [47%]), landing from a jump (n = 8 [22%]), and defensive cut (n = 5 [14%]). Injuries generally involved knee flexion (with minimal hip/trunk flexion and reduced plantarflexion) in the sagittal plane and knee valgus loading in most cases (75%). A similar number of injuries occurred during the first (53%) and second (47%) halves of the match, with a higher prevalence in the second (37%) and fourth (34%) quarters. Half of the injuries occurred during the first 10 minutes of effective playing time. More injuries occurred in guards (58%), and 73% of all injuries occurred in the scoring zone.

Conclusion

Indirect contact was the main injury mechanism found in male professional basketball players. The offensive cut was the most common situational pattern. Biomechanical analysis confirmed a multiplanar mechanism, with knee loading in the sagittal plane accompanied by dynamic valgus. More injuries occurred in the first 10 minutes of a player's effective playing time, within the scoring zone, and among guards.

Quadriceps muscle atrophy after non-invasive anterior cruciate ligament injury: evidence linking to autophagy and mitophagy

Introduction: Anterior cruciate ligament (ACL) injury is frequently accompanied by quadriceps muscle atrophy, a process closely linked to mitochondrial health and mitochondria-specific autophagy. However, the temporal progression of key quadricep atrophy-mediating events following ACL injury remains poorly understood. To advance our understanding, we conducted a longitudinal study to elucidate key parameters in quadriceps autophagy and mitophagy. Methods: Long-Evans rats were euthanized at 7, 14, 28, and 56 days after non-invasive ACL injury that was induced via tibial compression overload; controls were not injured. Vastus lateralis muscle was extracted, and subsequent immunoblotting analysis was conducted using primary antibodies targeting key proteins involved in autophagy and mitophagy cellular processes. Results: Our findings demonstrated dynamic changes in autophagy and mitophagy markers in the quadriceps muscle during the recovery period after ACL injury. The early response to the injury was characterized by the induction of autophagy at 14 days (Beclin1), indicating an initial cellular response to the injury. Subsequently, at 14 days we observed increase in the elongation of autophagosomes (Atg4B), suggesting a potential remodeling process. The autophagosome flux was also augmented between 14- and 28 days (LC3-II/LC3-I ratio and p62). Notably, at 56 days, markers associated with the elimination of damaged mitochondria were elevated (PINK1, Parkin, and VDAC1), indicating a possible ongoing cellular repair and restoration process. Conclusion: These data highlight the complexity of muscle recovery after ACL injury and underscore the overlooked but crucial role of autophagy and mitophagy in promoting the recovery process.

Increased knee torsional misalignment associated with femoral torsion is related to non-contact anterior cruciate ligament injury: a case-control study

BACKGROUND

Altered axial biomechanics of the knee are recognized as a risk factor for non-contact anterior cruciate ligament (ACL) injury. However, the relationship of knee and segmental torsion to non-contact ACL and combined anterolateral ligament (ALL) injury is unclear. This study aims to determine the relationship of knee and segmental torsion to non-contact ACL injury and to explore their relationship with ALL injuries.

METHODS

We divided 122 patients with arthroscopically confirmed non-contact ACL injuries into an ACL injury group (isolated ACL injury, 63 patients) and an ACL + ALL injury group (ACL combined with ALL injury,59 patients). Additionally, 90 normal patients with similar age, gender and body mass index (BMI) were matched as a control group. The tibial tubercle-trochlear groove (TT-TG) distance, distal femoral torsion (DFT), posterior femoral condylar torsion (PFCT) and proximal tibial torsion (PTT) were measured using magnetic resonance imaging (MRI). We assessed the differences between the groups using an independent samples t test and utilized receiver operating characteristic (ROC) curves to determine the cut-off value for the increased risk of ACL injury.

RESULTS

In patients with ACL injury, the measurements of the TT-TG (11.8 ± 3.1 mm), DFT (7.7° ± 3.5°) and PFCT (3.6° ± 1.3°) were significantly higher compared to the control group (9.1 ± 2.4 mm, 6.3° ± 2.7° and 2.8° ± 1.3°, respectively; P < 0.05), but the PTT did not differ between the two groups. The TT-TG, DFT and PFCT were not significantly larger in patients combined with ALL injury. ROC curve analysis revealed ACL injury is associated with TT-TG, DFT and PFCT.

CONCLUSIONS

Knee torsional alignment is associated with ACL injury, predominantly in the distal femur rather than the proximal tibia. However, its correlation with ALL injury remains unclear. These findings may help identify patients at high risk for non-contact ACL injury and inform the development of targeted prevention and treatment strategies.

Two-to-three times increase in natural hip and lumbar non-sagittal plane kinematics can lead to anterior cruciate ligament injury and cartilage failure scenarios during single-leg landings

BACKGROUND

Analyzing sports injuries is essential to mitigate risk for injury, but inherently challenging using in vivo approaches. Computational modeling is a powerful engineering tool used to access biomechanical information on tissue failure that cannot be obtained otherwise using traditional motion capture techniques.

METHODS

We extrapolated high-risk kinematics associated with ACL strain and cartilage load and stress from a previous motion analysis of 14 uninjured participants. Computational simulations were used to induce ACL failure strain and cartilage failure load, stress, and contact pressure in two age- and BMI-matched participants, one of each biological sex, during single-leg cross drop and single-leg drop tasks. The high-risk kinematics were exaggerated in 20% intervals, within their physiological range of motion, to determine if injury occurred in the models. Where injury occurred, we reported the kinematic profiles that led to tissue failure.

FINDINGS

Our findings revealed ACL strains up to 9.99%, consistent with reported failure values in existing literature. Cartilage failure was observed in all eight analyzed conditions when increasing each high-risk kinematic parameter by 2.61 ± 0.67 times the participants' natural landing values. The kinematics associated with tissue failure included peak hip internal rotation of 22.48 ± 19.04°, peak hip abduction of 22.51 ± 9.09°, and peak lumbar rotation away from the stance limb of 11.56 ± 9.78°.

INTERPRETATION

Our results support the ability of previously reported high-risk kinematics in the literature to induce injury and add to the literature by reporting extreme motion limits leading to injurious cases. Therefore, training programs able to modify these motions during single-leg landings may reduce the risk of ACL injury and cartilage trauma.

Hormonal contraception for female athletes presents special needs and concerns

PURPOSE

Oral contraceptives (OCs) are commonly used by female athletes raising concerns regarding the possible adverse effects of OCs on physical performance, musculoskeletal injuries, and bone density. We aimed to review all current studies on the physiological effects of OCs in physically active women.

MATERIALS AND METHODS

A review of literature in electronic search in PubMed and Google Scholar databases from December 2002 to December 2022 using relevant keywords. The reference lists of the articles found eligible were also reviewed.

RESULTS

Out of 344 articles in the initial database, 54 clinical studies were eligible for inclusion in our literature review. OCs are used by about two-thirds of female athletes. Current research suggests that OCs' effects on endurance performance and muscle strength are mostly reassuring. OCs do not seem to have a major negative impact on bone health or sports injuries. In fact, new data suggests that they may even significantly reduce the risk of anterior cruciate ligament (ACL) injury.

CONCLUSIONS

OCs can be safely used by young female athletes, who may also benefit from better menstrual cycle control. OCs offer newly realised protection from ACL injuries. The use of OCs must be carefully individualised according to their preferences, expectations, and experience.

Management after acute injury of the anterior cruciate ligament (ACL). Part 3: Recommendation on surgical treatment

PURPOSE

The aim of this consensus project was to give recommendations regarding surgical treatment of the anterior cruciate ligament (ACL) injured patient.

METHODS

For this consensus process, an expert, steering and rating group was formed. In an initial online meeting, the steering group, together with the expert group, formed various key topic complexes for which multiple questions were formulated. For each key topic, a structured literature search was performed by the steering group. The results of the literature review were sent to the rating group with the option to give anonymous comments until a final consensus voting was performed. Sufficient consensus was defined as 80% agreement.

RESULTS

During this consensus process, 30 topics regarding the surgical management and technique of ACL reconstruction were identified. The literature search for each key question resulted in 30 final statements. Of these 30 final statements, all achieved consensus.

CONCLUSIONS

This consensus process has shown that surgical treatment of ACL injury is a complex process. Various surgical factors influence patient outcomes. The proposed treatment algorithm can be used as a decision aid for the surgeon.

LEVEL OF EVIDENCE

Level V.

Knee-Related Quality of Life Compared Between 20 and 35 Years After an Anterior Cruciate Ligament Injury Treated Surgically With Primary Repair or Reconstruction, or Nonsurgically

BACKGROUND

Quality of life (QoL) is affected up to 5 years after an anterior cruciate ligament (ACL) injury. Knee impairment and osteoarthritis (OA) development increase over time, and this may affect QoL at a long-term follow-up.

PURPOSE

To investigate changes in health- and knee-related QoL between 20 and 35 years after ACL injury and compare it between patients treated with or without ACL surgery, as well as to study how symptomatic OA (SOA) is associated with change in QoL.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Between 1980 and 1983, 139 patients with acute ACL rupture were allocated to surgical or nonsurgical treatment of the ACL. Both groups completed a structured rehabilitation program. Of those patients, 59 were followed for 20 and 35 years after ACL rupture. After 10 crossovers, 33 patients were treated with primary repair or ACL reconstruction, and 26 were treated without ACL surgery. Combined radiographic OA and knee symptoms at 35 years was defined as SOA. QoL was assessed at 20 and 35 years after injury with the Knee injury and Osteoarthritis Outcome Score QoL (KOOS-QoL) subscale (range, 1-100), ACL-QoL questionnaire (total score and 5 subscales; range, 1-100), European QoL-5 Dimensions Questionnaire, and visual analog scale. Results were analyzed with paired and independent-sample t tests and chi-square tests.

RESULTS

Knee-related QoL was impaired at both 20 and 35 years after ACL injury, and differences were dependent on the measurement outcome. In the total cohort, KOOS-QoL did not change but both total ACL-QoL score (7.1 points; 95% CI, 2.2-11.9) and 4 of 5 subscales (5-10 points) decreased (P < .05). No differences were found between treatment groups. QoL decreased overall in patients with SOA, with a 21-point difference within-group change in KOOS-QoL (SOA or non-SOA) between 20 and 35 years of follow-up (P = .001; Cohen d = 1.0).

CONCLUSION

An ACL injury impairs knee-related QoL for up to 35 years, with no difference between treatment approaches (initial repair or later reconstruction compared with nonsurgical treatment). The deterioration decreases with longer follow-up. Clinicians should be aware of differences in QoL depending on the measurement outcome.

Relationship between Anterior Cruciate Ligament Injury and Subtalar Pronation in Female Basketball Players: Case-Control Study

Anterior cruciate ligament (ACL) injuries are a common issue in basketball. Several studies point to subtalar pronation as a relevant risk factor for these injuries, despite their multiarticular and multiplanar nature. This study evaluated the correlation between subtalar pronation and ACL injuries in female basketball players. A total of 30 players were recruited and divided into two groups: 15 with previous ACL injury and 15 without injury. The navicular drop test (NDT) and drop vertical jump test were applied to quantify parameters such as navicular drop, calcaneal eversion, ankle dorsiflexion, knee flexion, and dynamic valgus. The results showed significantly higher NDT values (6.93 ± 1.64 mm vs. 5.41 ± 1.96 mm, p = 0.029) and maximum calcaneal eversion angle (10.94 ± 3.22° vs. 5.30 ± 3.33°, p < 0.001) in the injured group. There were also significant differences in maximum dynamic valgus (152.73 ± 15.00° vs. 165.26 ± 5.628°, p = 0.005) and knee flexion (93.70 ± 7.47° vs. 82.92 ± 11.14°, p = 0.004) between groups. These findings suggest that subtalar pronation, assessed by NDT, and calcaneal eversion could be indicators of higher susceptibility to ACL injuries in female basketball players.

From Inflammation to Resolution: Specialized Pro-resolving Mediators in Posttraumatic Osteoarthritis

PURPOSE OF REVIEW

To provide a comprehensive overview of the inflammatory response following anterior cruciate ligament (ACL) injury and to highlight the relationship between specialized pro-resolving mediators (SPMs) and inflammatory joint conditions, emphasizing the therapeutic potential of modulating the post-injury resolution of inflammation to prevent posttraumatic osteoarthritis (PTOA).

RECENT FINDINGS

The inflammatory response triggered after joint injuries such as ACL tear plays a critical role in posttraumatic osteoarthritis development. Inflammation is a necessary process for tissue healing, but unresolved or overactivated inflammation can lead to chronic diseases. SPMs, a family of lipid molecules derived from essential fatty acids, have emerged as active players in the resolution of inflammation and tissue repair. While their role in other inflammatory conditions has been studied, their relationship with PTOA remains underexplored. Proinflammatory mediators contribute to cartilage degradation and PTOA pathogenesis, while anti-inflammatory and pro-resolving mediators may have chondroprotective effects. Therapies aimed at suppressing inflammation in PTOA have limitations, as inflammation is crucial for tissue healing. SPMs offer a pro-resolving response without causing immunosuppression, making them a promising therapeutic option. The known onset date of PTOA makes it amenable to early interventions, and activating pro-resolving pathways may provide new possibilities for preventing PTOA progression. Harnessing the pro-resolving potential of SPMs may hold promise for preventing PTOA and restoring tissue homeostasis and function after joint injuries.

The Dutch language short Anterior Cruciate Ligament-Return to Sport after Injury scale has good to excellent construct validity, internal consistency, and test-retest reliability when assessing athletes undergoing rehabilitation after ACL injury or ACL reconstruction

OBJECTIVES

To examine the validity and reliability of the Dutch language short Anterior Cruciate Ligament-Return to Sport after Injury scale (short ACL-RSI-NL) in recreational athletes undergoing rehabilitation after ACL injury or ACL reconstruction (ACLR).

METHODS

The original 12-item version of the ACL-RSI had been translated into Dutch. Short ACL-RSI-NL items were derived from this 12-item Dutch version. Content validity was evaluated by a team consisting of eight ACL experts and eight athletes. A cohort of 115 athletes with ACL injury or after ACLR completed the short ACL-RSI-NL and related questionnaires at various time points during their rehabilitation. Construct validity (hypothesis testing using Spearman correlations), internal consistency (Cronbach's alpha), floor and ceiling effects (percentage of athletes having the lowest or highest score possible), and structural validity (exploratory factor analysis) were evaluated in the entire ACL athlete group. Test-retest reliability (using intra-class correlation, ICC; standard error of measurement, SEM; smallest detectable change, SDC, at both group and individual levels) was investigated in a subgroup of athletes with a stable outcome on psychological readiness within a two-week interval (n ​= ​27).

RESULTS

The short ACL-RSI-NL demonstrated good construct validity (83% of hypotheses confirmed). Internal consistency was excellent (Cronbach's alpha 0.84), and there were no floor and ceiling effects (≤13.9% lowest or highest score). Test-retest reliability was good (ICC 0.89 with 95% CI 0.77-0.95, SEM 6.93, SDC individual level 19.2, SDC group level 3.7). Exploratory factor analysis confirmed the presence of a single underlying factor (accounting for 56.4% of the total variance of the score).

CONCLUSION

The short ACL-RSI-NL exhibited good to excellent construct validity, internal consistency, and test-retest reliability. An averaged score ranging from 0 to 100 can be used to measure psychological readiness to return to sport. The short ACL-RSI-NL has potential for use in day-to-day practice to assess the psychological readiness of recreational athletes to return to sport after ACL injury or ACLR during their rehabilitation process.

LEVEL OF EVIDENCE

Level II.

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.

A multicomponent neuromuscular warm-up program reduces lower-extremity injuries in trained basketball players: a cluster randomized controlled trial

OBJECTIVE

To assess the effects of a novel multicomponent neuromuscular warm-up program on lower-extremity injury incidence in basketball players competing at the regional level.

METHODS

A cluster randomized controlled experimental design was adopted to compare injury incidence between players exposed to the injury prevention warm-up program and those exposed to a typical warm-up program across an entire basketball season. Four teams consisting of 57 players (male: n = 42; female: n = 15) were allocated to the intervention group (age: 21.6 ± 2.5 years; height: 186.2 ± 8.8 cm; body mass: 80.0 ± 10.4 kg) and four teams consisting of 55 players (male: n = 43; female: n = 12) were allocated to the control group (age: 21.6 ± 2.6 years; height: 186.9 ± 9.1 cm; body mass: 81.5 ± 10.9 kg). The novel warm-up combined running exercises with active stretching, plyometrics, balance, strength, and agility drills. Coaching and medical staff provided details on injury incidence each week. Data analyses included the use of poisson regression analyses and the incidence rate ratio (IRR) with 95% confidence intervals (CI).

RESULTS

The intervention group experienced a significantly lower ankle sprain incidence rate (IRR = 0.26, 95% CI = 0.05, 0.98, p = 0.02) and a tendency toward a lower knee injury incidence rate (IRR = 0.32, 95% CI = 0.03, 1.78, p = 0.07) compared to the control group. Considering only non-contact lower-extremity injuries of any type, the intervention group experienced a significantly lower incidence rate compared to the control group (IRR = 0.26, 95% CI = 0.05, 0.98, p < 0.001).

CONCLUSION

This multi-team study demonstrated a novel multicomponent warm-up program resulted in less lower-extremity injuries, particularly ankle sprains and knee injuries, compared to a typical warm-up program in regional-level male and female basketball players.

The influence of distribution, severity and volume of posttraumatic bone bruise on functional outcome after ACL reconstruction for isolated ACL injuries

INTRODUCTION

Posttraumatic MRI of ACL tears show a high prevalence of bone bruise (BB) without macroscopic proof of chondral damage. Controversial results are described concerning the association between BB and outcome after ACL tear. Aim of this study is to evaluate the influence of distribution, severity and volume of BB in isolated ACL injuries on function, quality of life and muscle strength following ACL reconstruction (ACLR).

MATERIALS AND METHODS

MRI of n = 122 patients treated by ACLR without concomitant pathologies were evaluated. BB was differentiated by four localizations: medial/lateral femoral condyle (MFC/LFC) and medial/lateral tibial plateau (MTP/LTP). Severity was graded according to Costa-Paz. BB volumes of n = 46 patients were quantified (software-assisted volumetry). Outcome was measured by Lysholm Score (LS), Tegner Activity Scale (TAS), IKDC, isokinetics and SF-36. Measurements were conducted preoperatively (t0), 6 weeks (t1), 26 weeks (t2) and 52 weeks (t3) after ACLR.

RESULTS

The prevalence of BB was 91.8%. LTP was present in 91.8%, LFC 64.8%, MTP 49.2% and MFC 28.7%. 18.9% were classified Costa-Paz I, 58.2% II and 14.8% III. Total BB volume was 21.84 ± 15.27 cm3, the highest value for LTP (14.31 ± 9.93 cm3). LS/TAS/IKDC/SF-36/isokinetics improved significantly between t0-t3 (p < 0.001). Distribution, severity and volume had no influence on LS/TAS/IKDC/SF-36/isokinetics (n.s.).

CONCLUSIONS

No impact of BB after ACLR on function, quality of life and objective muscle strength was shown, unaffected by concomitant pathologies. Previous data regarding prevalence and distribution is confirmed. These results help surgeons counselling patients regarding the interpretation of extensive BB findings. Long-time follow-up studies are mandatory to evaluate an impact of BB on knee function due to secondary arthritis.

Effect of moxibustion on knee joint stiffness characteristics in recreational athletes pre- and post-fatigue

Objective

Joint stiffness results from the coupling of the nervous system and joint mechanics, and thus stiffness is a comprehensive representation of joint stability. It has been reported that moxibustion can alleviate general weakness and fatigue symptoms and subsequently may influence joint stiffness. This study investigated whether moxibustion could enhance knee joint stiffness in recreational athletes pre- and post-fatigue.

Methods

Eighteen participants were randomized into intervention (5 males: 20.6 ± 1.5 yr; 4 females: 20.8 ± 1.5 yr) and control groups (5 males: 19.4 ± 0.9 yr; 4 females: 20.5 ± 0.6 yr). The intervention group received indirect moxibustion applied to acupoints ST36 (bilateral) and CV4 for 30 min every other day for 4 consecutive weeks. The control group maintained regular exercise without moxibustion. Peak torque (PT) of right knee extensor, relaxed and contracted muscle stiffness (MS) of vastus lateralis, and knee extensor musculoarticular stiffness (MAS) was assessed with an isokinetic dynamometer (IsoMed 2000), myometer, and free oscillation technique, respectively. Measurements were taken at three time points: pre-intervention, post-intervention/pre-fatigue, and post-fatigue.

Results

MAS (P = 0.006) and PT (P = 0.007) in the intervention group increased more from pre-to post-intervention compared with the control group. Post-fatigue MAS (P = 0.016) and PT (P = 0.031) increased more in the intervention group than in the control group.

Conclusion

Moxibustion enhanced PT and knee MAS, suggesting that this intervention could be used in injury prevention and benefit fatigue resistance in young recreational athletes.

Is an Exercise-Based Injury Prevention Programme Effective in Team Handball Players? A Systematic Review and Meta-Analysis

OBJECTIVE

This systematic review and meta-analysis aimed to assess the effectiveness of exercise-based injury prevention programmes in preventing sports injuries in team handball players.

DATA SOURCES

Two independent researchers performed a systematic search in the electronic databases Scopus, PubMed, Web of Science (WOS), SPORTDiscus, and CINAHL from inception until Aprile 2023.

STUDY SELECTION

Studies were included if they were randomized-controlled or prospective cohort trials, contained a population of competitive team handball players, included an intervention designed specifically to prevent or reduce the risk of team handball injury, and reported injury incidence rates specific to team handball players. Two researchers independently assessed trials for inclusion criteria and methodological quality.

DATA EXTRACTION

Study design, intervention details, participant characteristics, and the number of injuries in each group were extracted from each study by two independent researchers. The outcome of interest was the incidence rate of injury. Injury data were classified into 5 groups: lower extremity injuries, shoulder injuries, knee injuries, ankle sprains, or ACL injuries. Extracted data were analyzed by Comprehensive Meta-Analysis software, version 3.0 (CMA.V2) using a random-effects model to compute the overall effect estimates of injury prevention programmes in reducing the risk of injuries. Odds ratios (ORs) with 95% CIs were calculated based on the number of injuries in each group.

DATA SYNTHESIS

Meta-analyses were conducted independently for each injury classification. Results indicate that prevention programmes significantly reduced the risk of shoulder injuries (OR, 0.56; 95% CI, 0.36-0.87; P = 0.01), lower extremity (OR, 0.59; 95% CI, 0.37-0.98; P = 0.03), knee (OR, 0.53; 95% CI, 0.35-0.78; P = 0.002) and ankle sprains (OR, 0.57; 95% CI, 0.40-0.81; P = 0.002), and ACL ruptures (OR, 0.67; 95% CI, 0.45-0.97; P = 0.03) in team handball players.

CONCLUSION

In team handball players, prevention programmes appear effective in reducing the risk of shoulder, lower extremity, knee, ankle, and ACL injuries.

Lateral-medial asymmetry of posterior tibial slope and small lateral tibial plateau articular surface depth are morphological factors of lateral meniscus posterior root tears in ACL-injured patients

PURPOSE

To investigate whether knee morphological features, patient characteristics, and intraoperative findings are associated with a lateral meniscus (LM) posterior root tear (LMPRT) in anterior cruciate ligament (ACL) injuries with the integrated data from two academic centres.

METHODS

This retrospective study used registry data acquired prospectively at two academic centres. Patients with ACL reconstruction (ACLR) with LMPRT and no other LM injury were selected (LMPRT group) from each database. The control group included patients who underwent ACLR without LM tears. Patients were matched to the LMPRT group according to age and gender (1:1). Morphological factors evaluated on preoperative magnetic resonance image scans included lateral femoral condyle (LFC) anterior-posterior diameter, height, and depth; lateral tibial plateau (LTP) articular surface (AS) depth and sagittal plane depth; and lateral and medial posterior tibial slopes (PTSs). LFC height and depth ratios, LTP AS depth and sagittal plane depth ratios, and lateral-to-medial slope asymmetry were computed from previous measurements. Patient characteristics and intraoperative findings were extracted and compared between both groups.

RESULTS

The study included 252 patients (126 in each group). The lateral-medial asymmetry of PTS was greater in the LMPRT group (1.2° vs 0.3°, p < 0.05), and the LTP AS depth was smaller in the LMPRT group (31.4 mm vs 33.2 mm, p < 0.01). There were no differences in LFC morphology between the control and LMPRT groups. Pivot shift grade (p < 0.05), percentage of complete ACL tears (p < 0.05), and medial meniscus ramp lesions (p < 0.05) were significantly higher in the LMPRT group.

CONCLUSION

LMPRT was associated with significantly increased lateral-medial asymmetry of PTS and significantly smaller LTP AS depth. LMPRT was also associated with an increase in the preoperative pivot shift grade and the presence of a medial meniscus ramp lesion. These morphological characteristics are rather simple to measure and would serve as helpful indicators to preoperatively detect LMPRT, which is frequently challenging to diagnose preoperatively.

LEVEL OF EVIDENCE

Level III.

Major Increase in Incidence of Pediatric ACL Reconstructions From 2005 to 2021: A Study From the Norwegian Knee Ligament Register

BACKGROUND

The incidence of pediatric and adolescent anterior cruciate ligament reconstruction (ACLR) is increasing in several countries. It is uncertain whether this trend applies to countries that traditionally prefer an initial nonoperative treatment approach whenever possible, like Norway. Nationwide, long-term patient-reported outcomes and revision rates after ACLR in the pediatric population are also lacking.

PURPOSE

To determine the incidence of pediatric ACLR in Norway since 2005, as well as to detect trends in surgical details and describe patient-reported outcomes up to 10 years after ACLR.

STUDY DESIGN

Descriptive cohort study.

METHODS

This study is based on prospectively collected data on girls ≤14 years and boys ≤16 years, registered in the Norwegian Knee Ligament Register at the time of their primary ACLR, between 2005 and 2021. The main outcome was the incidence of ACLR, adjusted to the corresponding population numbers for each year. The time trend was analyzed by comparing the mean of the first and last 3-year period (2005-2007 and 2019-2021). Patient-reported outcomes were assessed using the Knee injury and Osteoarthritis Outcome Score preoperatively and at 2, 5, and 10 years postoperatively.

RESULTS

A total of 1476 patients (1484 cases) were included, with a mean follow-up of 8.1 years (range, 1-17). The incidence of pediatric ACLRs per 100,000 population increased from 18 to 26, which corresponds to an increase of 40% for boys and 55% for girls. Concurrent meniscal procedures increased significantly from 45% to 62%, and the proportion of meniscal repairs increased from 19% to 43% when comparing the first and last time period. The mean Knee injury and Osteoarthritis Outcome Score values for the Sport and Recreation and Quality of Life subscales were between 72 and 75 at the 2-, 5- and 10-year follow-up. The 5-year revision rate was 9.9%.

CONCLUSION

There was a major increase in incidence of pediatric ACLR in Norway during the study period. There was a shift in the approach to concomitant meniscal procedures from resection to repair, with more than a doubling of the proportion of meniscal repairs. Patient-reported outcomes revealed long-lasting reduced knee function.

Clinical, Biomechanical, and Self-reported Health Status After ACL Reconstruction With Meniscal Repair in Soccer Players: Results at Minimum 1-Year Follow-up

Background

Performing meniscal repair with anterior cruciate ligament reconstruction (ACLR) has been shown to contribute to the long-term preservation of knee health and gait biomechanics.

Purpose

To evaluate the role of meniscal repair in the performance of semiprofessional soccer players who returned to sport after ACLR.

Study Design

Case series; Level of evidence, 4.

Methods

This study included 51 male soccer players (mean ± SD age, 28.82 ± 5.33 years) who underwent ACLR at a single institution between July 2018 and July 2019. The players were divided into 3 groups according to surgery type: ACLR only (n = 30), ACLR with lateral meniscal repair (n = 9), and ACLR with medial meniscal repair (n = 12). Outcomes were evaluated through clinical examination, self-reported health questionnaires (Cincinnati Knee Rating System, Tegner activity score, Tegner Lysholm Knee Scoring Scale, Tampa Scale of Kinesiophobia, and ACL-Return to Sport After Injury), and biomechanical performance evaluations (balance, strength, coordination, and symmetry tests). Parametric and nonparametric tests were carried out for multiple comparisons.

Results

The mean ± SD follow-up time was 20.75 ± 9.38 months. Although no significant differences emerged in clinical and self-reported health status, almost all the physical parameters tested resulted in lower performance in players treated with ACLR and meniscal repair. Moreover, patients with ACLR with lateral meniscal repair reported higher pain and fear of reinjury, with lower outcomes in terms of strength, symmetry, and coordination as compared with the other 2 groups. Balance abilities were significantly affected in players who underwent meniscal repair as compared with those who underwent ACLR only.

Conclusion

The findings showed that biomechanical performance measures and fear of reinjury were significantly worse in soccer players with associated meniscal repair at a minimum 1-year follow-up, especially in those with a lateral meniscal tear.

Acute Bone Loss and Infrapatellar Fat Pad Fibrosis in the Knee After an In Vivo ACL Injury in Adolescent Mice

BACKGROUND

Young patients are 6 times more likely than adults to have a primary anterior cruciate ligament (ACL) graft failure. Biological factors (ie, tunnel osteolysis) may account for up to a third of these failures. Previous evaluations of patient ACL explants indicated significant bone loss within the entheseal regions. However, it remains unknown if the degree of bone loss within the ACL insertion regions, wherein ACL grafts are fixated, exceeds that of the femoral and tibial condylar bone.

HYPOTHESIS

Bone loss in the mineralized matrices of the femoral and tibial ACL entheses is distinct from that clinically reported across the whole knee after injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

We developed a clinically relevant in vivo mouse ACL injury model to cross-sectionally track the morphological and physiological postinjury changes within the ACL, femoral and tibial entheses, synovial joint space, and load-bearing epiphyseal cortical and trabecular bone components of the knee joint. Right ACLs of 10-week-old C57BL/6J female mice (N = 75) were injured in vivo with the contralateral ACLs serving as controls. Mice were euthanized at 1, 3, 7, 14, or 28 days after injury (n = 12/cohort). Downstream analyses included volumetric cortical and trabecular bone analyses and histopathologic assessments of the knee joint after injury. Gait analyses across all time points were also performed (n = 15 mice).

RESULTS

The majority of the ACL injuries in mice were partial tears. The femoral and tibial cortical bone volumes were 39% and 32% lower, respectively, at 28 days after injury than those of the uninjured contralateral knees (P < .01). Trabecular bone measures demonstrated little difference between injured and control knees after injury. Across all bone measures, bone loss was similar between the injured knee condyles and ACL entheses. There was also significant inflammatory activity within the knee after injury. By 7 days after injury, synovitis and fibrosis were sigificantly elevated in the injured knee compared with the controls (P < .01), which corresponded with significantly higher osteoclast activity in bone at this time point compared with the controls. This inflammatory response signficantly persisted throughout the duration of the study (P < .01). The hindlimb gait after injury deviated from normal, but mice habitually loaded their injured knee throughout the study.

CONCLUSION

Bone loss was acute and persisted for 4 weeks after injury in mice. However, the authors' hypothesis was not confirmed, as bone quality was not significantly lower in the entheses compared with the condylar bone regions after injury. With relatively normal hindlimb loading but a significant physiological response after injury, bone loss in this model may be driven by inflammation.

CLINICAL RELEVANCE

There is persistent bone resorption and fibrotic tissue development after injury that is not resolved. Inflammatory and catabolic activity may have a significant role in the postinjury decline of bone quality in the knee.

Effect of Whole Body Parameters on Knee Joint Biomechanics: Implications for ACL Injury Prevention During Single-Leg Landings

BACKGROUND

Previous studies have examined the effect of whole body (WB) parameters on anterior cruciate ligament (ACL) strain and loads, as well as knee joint kinetics and kinematics. However, articular cartilage damage occurs in relation to ACL failure, and the effect of WB parameters on ACL strain and articular cartilage biomechanics during dynamic tasks is unclear.

PURPOSES

(1) To investigate the effect of WB parameters on ACL strain, as well as articular cartilage stress and contact force, during a single-leg cross drop (SLCD) and single-leg drop (SLD). (2) To identify WB parameters predictive of high ACL strain during these tasks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Three-dimensional motion analysis data from 14 physically active men and women were recorded during an SLCD and SLD. OpenSim was used to obtain their kinematics, kinetics, and muscle forces for the WB model. Using these data in kinetically driven finite element simulations of the knee joint produced outputs of ACL strains and articular cartilage stresses and contact forces. Spearman correlation coefficients were used to assess relationships between WB parameters and ACL strain and cartilage biomechanics. Moreover, receiver operating characteristic curve analyses and multivariate binary logistic regressions were used to find the WB parameters that could discriminate high from low ACL strain trials.

RESULTS

Correlations showed that more lumbar rotation away from the stance limb at peak ACL strain had the strongest overall association (ρ = 0.877) with peak ACL strain. Higher knee anterior shear force (ρ = 0.895) and lower gluteus maximus muscle force (ρ = 0.89) at peak ACL strain demonstrated the strongest associations with peak articular cartilage stress or contact force in ≥1 of the analyzed tasks. The regression model that used muscle forces to predict high ACL strain trials during the dominant limb SLD yielded the highest accuracy (93.5%), sensitivity (0.881), and specificity (0.952) among all regression models.

CONCLUSION

WB parameters that were most consistently associated with and predictive of high ACL strain and poor articular cartilage biomechanics during the SLCD and SLD tasks included greater knee abduction angle at initial contact and higher anterior shear force at peak ACL strain, as well as lower gracilis, gluteus maximus, and medial gastrocnemius muscle forces.

CLINICAL RELEVANCE

Knowledge of which landing postures create a high risk for ACL or cartilage injury may help reduce injuries in athletes by avoiding those postures and practicing the tasks with reduced high-risk motions, as well as by strengthening the muscles that protect the knee during single-leg landings.

Decreased Synovial Fluid Ghrelin Level Is Associated With Acute Cartilage Injury in Patients With Anterior Cruciate Ligament Tear

Background

Ghrelin, an amino acid hormone secreted primarily from the stomach, can regulate bone metabolism, regulate inflammation via suppressing proinflammatory cytokines, and suppress expression of matrix metalloproteinases (MMPs).

Purpose

To measure synovial fluid levels of ghrelin in young patients with anterior cruciate ligament (ACL) tear to assess the role of ghrelin as a potential biomarker for cartilage injury.

Study Design

Controlled laboratory study.

Methods

This study included 120 patients who underwent ACL reconstructionbetween January 1, 2016, and May 31, 2021. We categorized 60 patients with acute cartilage injury (International Cartilage Regeneration & Joint Preservation Society grade 2 or 3) as the acute group and 60 patients with no acute cartilage injury as the nonacute group, with the healthy contralateral knee of each patient acting as the control group (n = 120). Synovial fluid samples were collected from the knees in the operating room before ACL reconstruction. We assessed the inflammatory biomarkers interleukin (IL)-6, MMP-1, MMP-9, and MMP-13, as well as serum ghrelin level and Mankin score, and results were compared between the 3 study groups with the Mann-Whitney U test.

Results

Lower serum ghrelin levels in the synovial fluid were found in the acute group compared with the nonacute group and healthy controls (232.4 vs 434.4 vs 421.5 pg/mL, respectively; P < .001). Ghrelin level in the synovial fluid was significantly and positively correlated with IL-6 (r = 0.4223; P < .0001), MMP-13 (r = 0.3402; P < .0001), and Mankin score (r = 0.1453; P = .0244).

Conclusion

In patients with ACL injury, ghrelin synovial fluid was significantly differently expressed in patients with cartilage injury and no cartilage injury.

Clinical Relevance

Ghrelin synovial fluid has the potential to be a biomarker to predict acute cartilage injury in patients with ACL injury.

Development of Anatomic Risk Factors for ACL Injuries: A Comparison Between ACL-Injured Knees and Matched Controls

BACKGROUND

Several tibiofemoral anatomic features have been repeatedly associated with increased anterior cruciate ligament (ACL) injury risk. Previous studies have highlighted age and sex differences among these anatomic risk factors, but little is known about the normal and pathologic development of these differences during skeletal maturation.

PURPOSE

To investigate differences in anatomic risk factors at various stages of skeletal maturation between ACL-injured knees and matched controls.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

After institutional review board approval, magnetic resonance imaging scans from 213 unique ACL-injured knees (age, 7-18 years, 48% female) and 239 unique asymptomatic ACL-intact knees (age, 7-18 years, 50% female) were used to measure femoral notch width, posterior slope of the lateral and medial tibial plateau, medial and lateral tibial spinal height (MTSH, LTSH), medial tibial depth, and posterior lateral meniscus-bone angle. Linear regression was performed to assess change in quantified anatomic indices with age for male and female patients in the ACL-injured cohort. Two-way analysis of variance with Holm-Sidak post hoc testing was performed to compare anatomic indices between ACL-injured knees and ACL-intact controls in each age group.

RESULTS

In the ACL-injured cohort, notch width, notch width index and medial tibial depth increased with age (R2 > 0.1; P < .001) in both sexes. MTSH and LTSH increased with age only in boys (R2≥ 0.09; P≤ .001), whereas meniscus-bone angle decreased with age only in girls (R2 = 0.13; P < .001). There were no other age differences in quantified anatomic indices. Patients with ACL injury consistently had a significantly higher lateral tibial slope (P < .01) and smaller LTSH (P < .001) as compared with ACL-intact controls across all age groups and sexes. When compared with age- and sex-matched ACL-intact controls, ACL-injured knees had a smaller notch width (boys, 7-18 years; girls, 7-14 years; P < .05), larger medial tibial slope (boys and girls, 15-18 years; P < .01), smaller MTSH (boys, 7-14 years; girls, 11-14 years; P < .05), and larger meniscus-bone angle (girls, 7-10 years; P = .050).

CONCLUSION

The consistent morphologic differences throughout skeletal growth and maturation suggest a developmental role in high-risk knee morphology. The observed high-risk knee morphology at an earlier age preliminarily suggests the potential of knee anatomy measurements in identifying those with a predisposition toward ACL injury.

Medial Meniscal Posterior Horn Suturing Influences Tibial Internal-External Rotation in ACL-Reconstructed Knees

Background

The role of meniscal lesions and repair in combination with anterior cruciate ligament (ACL) injury and reconstruction has not been extensively investigated in vivo and under weightbearing conditions.

Purpose

The purposes of this study were to (1) compare the in vivo knee kinematics between patients with ACL tear and those with combined ACL and medial meniscal tears and (2) investigate kinematic differences between isolated ACL reconstruction and ACL reconstruction plus medial meniscal repair (MR). It was hypothesized that concomitant posterior horn medial meniscal tear and ACL deficiency would affect knee internal-external rotation and anterior-posterior translation but MR would restore these parameters.

Study Design

Controlled laboratory study.

Methods

Nineteen patients who underwent ACL reconstruction were included: 10 had intact menisci (IM group) and 9 had a medial meniscal injury that was repaired during ACL reconstruction using an all-inside technique (MR group). Preoperatively and 18 months postoperatively, active knee kinematics under weightbearing conditions was evaluated during a single-leg squat using a dynamic biplane x-ray imaging system. The general linear model was used to investigate the differences between group (IM vs MR) and time (preoperative vs follow-up) and their interactions.

Results

Tibial internal rotation was higher in the MR group than the IM group both before and after surgery (P = .007). Knee valgus rotation was higher in the MR group preoperatively (P < .001), while no differences were found postoperatively because of an increase of valgus rotation in the IM group, which was significant in the descendant phase (P < .001). Preoperatively, the IM group showed a more medial tibial translation compared with the MR group in the descendant phase (P = .006).

Conclusion

When performing a single-leg squat, patients with ACL-deficient knees and a medial meniscal tear demonstrated a more valgus rotation, tibial internal rotation, and lateral tibial translation versus those with intact menisci. After ACL reconstruction and MR, these patients demonstrated significantly higher tibial internal rotation when compared with patients who underwent isolated ACL reconstruction.

Clinical Relevance

Surgeons should be aware that MR does not fully restore knee kinematics in vivo and under weightbearing conditions in the context of ACL reconstruction.

Mesenchymal progenitor cells from non-inflamed versus inflamed synovium post-ACL injury present with distinct phenotypes and cartilage regeneration capacity

BACKGROUND

Osteoarthritis (OA) is a chronic debilitating disease impacting a significant percentage of the global population. While there are numerous surgical and non-invasive interventions that can postpone joint replacement, there are no current treatments which can reverse the joint damage occurring during the pathogenesis of the disease. While many groups are investigating the use of stem cell therapies in the treatment of OA, we still don't have a clear understanding of the role of these cells in the body, including heterogeneity of tissue resident adult mesenchymal progenitor cells (MPCs).

METHODS

In the current study, we examined MPCs from the synovium and individuals with or without a traumatic knee joint injury and explored the chondrogenic differentiation capacity of these MPCs in vitro and in vivo.

RESULTS

We found that there is heterogeneity of MPCs with the adult synovium and distinct sub-populations of MPCs and the abundancy of these sub-populations change with joint injury. Furthermore, only some of these sub-populations have the ability to effect cartilage repair in vivo. Using an unbiased proteomics approach, we were able to identify cell surface markers that identify this pro-chondrogenic MPC population in normal and injured joints, specifically CD82^LowCD59⁺ synovial MPCs have robust cartilage regenerative properties in vivo.

CONCLUSIONS

The results of this study clearly show that cells within the adult human joint can impact cartilage repair and that these sub-populations exist within joints that have undergone a traumatic joint injury. Therefore, these populations can be exploited for the treatment of cartilage injuries and OA in future clinical trials.

Relationship Between Lateral Tibial Posterior Slope and Tibiofemoral Kinematics During Simulated Jump Landings in Male Cadaveric Knees

Background

It is not known mechanistically whether a steeper lateral posterior tibial slope (LTS) leads to an increase in anterior tibial translation (ATT) as well as internal tibial rotation (ITR) during a given jump landing.

Hypothesis

A steeper LTS will result in increased ATT and ITR during simulated jump landings when applying knee compression, flexion, and internal tibial torque of increasing severity.

Study Design

Descriptive laboratory study.

Methods

Seven pairs of cadaveric knees were harvested from young male adult donors (mean ± SD; age, 25.71 ± 5.53 years; weight, 71.51 ± 4.81 kg). The LTS of each knee was measured by a blinded observer from 3-T magnetic resonance images. Two sets of 25 impact trials of ∼700 N (1× body weight [BW] ±10%) followed by 2 sets of 25 trials of 1400 N (2× BW ±10%) were applied to a randomly selected knee of each pair. Similarly, on the contralateral knee, 2 sets of 25 impact trials of ∼1800 N (2.5× BW ±10%) followed by 2 sets of 25 trials of ∼2100 N (3× BW ±10%) were applied. Three-dimensional knee kinematics, including ATT and ITR, were measured at 400 Hz using optoelectronic motion capture. Two-factor linear mixed effect models were used to determine the relationship of LTS to ATT and ITR as impact loading increased.

Results

As LTS increased, so did ATT and ITR during increasingly severe landings. LTS had an increasing effect on ATT (coefficient, 0.50; 95% CI, 0.29-0.71) relative to impact force (coefficient, 0.52; 95% CI, 0.50-0.53). ITR was proportional to LTS (coefficient, 1.36; 95% CI, 0.80-1.93) under increasing impact force (coefficient, 0.49; 95% CI, 0.47-0.52). For steeper LTS, the increase in ITR was proportionally greater than the increase in ATT.

Conclusion

In male knee specimens, a steeper LTS significantly increased ATT and ITR during jump landings.

Clinical Relevance

Increases in ITR and ATT during jump landings lead to increased strain on the anterior cruciate ligament and are therefore associated with greater risk of ligament failure.

ACL Reconstruction in a Poliotic Limb with Peroneus Longus Graft

Introduction

Prevalence of polio was very high in India before its eradication, with a number of people living with its residual effects. Anterior cruciate ligament (ACL) injury is the most common knee injury. To the best of our knowledge, this is the first report in literature presenting ACL injury in a poliotic limb and its management.

Case Report

A 30-year-old male with poliotic limb and equinovarus deformity presented with ACL injury to the same limb. ACL reconstruction was done using Peroneus longus graft. Postoperatively patient was gradually returned to preinjury activity levels.

Conclusion

ACL tears in a poliotic limb can be a challenging case. Proper preoperative planning and anticipation of problems can help in managing the case with a good outcome.

Awareness of Anterior Cruciate Ligament Injury-Preventive Training Programs among Saudi Athletes

BACKGROUND

Anterior cruciate ligament (ACL) tear is a common medical condition that entails a stretch or sprain of the ACL, which is present in the knee joint. The incidence of ACL injury in the Kingdom of Saudi Arabia is estimated to be 31.4%. Prevention training programs (PTPs) can be used to reduce ACL injuries sustained during physical activity, as they primarily focus on improving strength, balance, and lower limb biomechanics and reducing landing impact. This study aimed to assess Saudi athletes' awareness of ACL injury PTPs.

METHODS

A cross-sectional survey in the form of a self-administered questionnaire in the Arabic language was carried out from 22 December 2022 to 7 March 2023 and included 1169 Saudi athletes. Statistical analyses were performed on the collected data using frequency and percentages. Binary logistic regression was used for the adjusted analysis and determining associations between athletes playing high- and low-risk sports.

RESULTS

Overall, 52% of participants were female athletes, and 48% were male athletes. The western region of the country had the highest response rate (28.9%). The most common sport played was football at 36.6%. Most participants (70.97%) reported that their information on ACL injury was taken by their coaches. When assessing whether participants were familiar with the concept of an ACL injury PTP, the majority of the participants answered no, representing 971 (662 high-risk, 309 low-risk), compared to those who answered yes, representing only 198 (167 high-risk, 31 low-risk), with a statistically significant difference (adjusted OR: 2.106; 95% confidence interval: 1.544-2.873; p-value < 0.001).

CONCLUSION

In general, the level of awareness of ACL injury PTPs among Saudi athletes was poor.

Tri-axial loading response to anti-gravity running highlights movement strategy compensations during knee injury rehabilitation of a professional soccer player

Anti-gravity treadmills have been used in rehabilitation to manipulate exposure to loading and to prescribe return to outside running. Analysis is typically restricted to the vertical plane, but tri-axial accelerometry facilitates multi-planar analysis with relevance to injury mechanism. In this case a professional male soccer player, 4 weeks post-operative surgery to repair a medial meniscectomy, 8 months after Anterior Cruciate Ligament reconstruction to the same knee, completed anti-gravity treadmill running at 70-95% bodyweight (BW) at 5% increments. Tri-axial accelerometers were placed proximal to the Achilles tendon of the injured and healthy leg, and at C7. The planar acceleration at touchdown highlighted an increase at 85% BW, identifying 70% and 85% BW as discrete loading progressions. C7 (3.21 ± 0.68 m·s^-2) elicited lower (P < 0.001) vertical acceleration than the lower limb (9.31 ± 1.82 m·s^-2), with no difference between limbs suggesting bilateral symmetry. However, in the medio-lateral plane the affected limb (-0.15 ± 1.82 m·s^-2) was exposed to lower (P = 0.001) medio-lateral acceleration than the non-affected limb (2.92 ± 1.35 m·s^-2) at touchdown, indicative of bilateral asymmetry. PlayerLoad during foot contact was sensitive to accelerometer location, with the affected limb exposed to greater loading in all planes (P ≤ 0.082), exacerbated at 90-95% BW. Tri-axial accelerometry provides a means of assessing multi-planar loading during rehabilitation, enhancing objective progression.

Gender Differences in Lower Extremity Stiffness during a Single-Leg Landing Motion in Badminton

In general, at the same level of exercise, female athletes are three to six times more likely to injure an anterior cruciate ligament (ACL) than male athletes. Female athletes also had higher rates of ACL injury than males in a single-leg landing task after a backcourt backhand side overhead stroke in badminton. In many previous studies, stiffness of the musculoskeletal system in the lower limbs has been reported as a potential factor contributing to differences in ACL injury rates between genders. The purpose of this study was to describe the differences between genders in leg and knee stiffness in male and female athletes during a single-leg landing action after the backhand side overhead shot in the backcourt. Eight male athletes and eight female athletes participated in this test. Leg stiffness and knee stiffness were calculated separately for male and female athletes during the landing phase. The results showed that both absolute and normalized leg stiffness were lower in female athletes than in male athletes (p < 0.05). And both absolute and normalized knee stiffness were also lower than male athletes (p < 0.05). The low leg stiffness and knee stiffness demonstrated by females in this single-leg drop task compared to male athletes may indicate that females have lower dynamic leg stability than males during the drop, which may lead to hypermobility of the knee joint and may put females at a higher risk of injury in this high-risk maneuver for non-contact cruciate ligament injuries.

Association of personal and equipment-related factors on ACL injury risk in alpine skiers with cautious or risk-taking behaviour: A case-control study

Background

In recreational alpine skiing ACL injury risk depends on the interaction of individual characteristics and behaviours as well as on equipment-related factors.

Aim

to evaluate if and to what extent personal characteristics and equipment-related parameters are associated with ACL injury risk in cautious and risk-taking recreational alpine skiers.

Methods

A retrospective questionnaire-based, case-control study of ACL-injured and uninjured in a cohort of cautious as well as risk-taking recreational skiers was conducted. Participants self-reported their demographics, skiing skill level, and risk-taking behaviour. Ski length, side-cut radius, widths of the tip, waist, and tail were recorded from each participant's skis. Standing heights at the front and rear components of the ski binding were measured with a digital sliding caliper, and a standing height ratio between the front and rear components was calculated. Ski boot sole abrasion at the toe and heel pieces was also measured with the digital sliding caliper.

Results

In total, 1068 recreational skiers (50.8% females) with a mean age of 37.8 ± 12.3 years participated, of whom 193 (22.0%) sustained an ACL injury, and 330 (30.9%) participants reported a risk-taking behaviour. Results of the multiple logistic regression analyses revealed that a higher age, a lower skill level, a higher standing height ratio, and greater ski boot sole abrasion at the toe as well as heel pieces were independently associated with an increased ACL injury risk in both the cautious and the risk-taking group. Among cautious skiers, a longer ski length was an additional significant risk factor for sustaining an ACL injury. In conclusion, the same personal and equipment related characteristics contribute to an increase in the ACL injury risk regardless of risk-taking behaviour, with the only difference that longer skis represent an additional risk factor in cautious skiers.

Effect of Heading a Soccer Ball as an External Focus During a Drop Vertical Jump Task

Background

Research has demonstrated that performing a secondary task during a drop vertical jump (DVJ) may affect landing kinetics and kinematics.

Purpose

To examine the differences in the trunk and lower extremity biomechanics associated with anterior cruciate ligament (ACL) injury risk factors between a standard DVJ and a DVJ while heading a soccer ball (header DVJ).

Study Design

Descriptive laboratory study.

Methods

Participants comprised 24 college-level soccer players (18 female and 6 male; mean ± SD age, 20.04 ± 1.12 years; height, 165.75 ± 7.25 cm; weight, 60.95 ± 8.47 kg). Each participant completed a standard DVJ and a header DVJ, and biomechanics were recorded using an electromagnetic tracking system and force plate. The difference (Δ) in 3-dimensional trunk, hip, knee, and ankle biomechanics between the tasks was analyzed. In addition, for each biomechanical variable, the correlation between the data from the 2 tasks was calculated.

Results

Compared to the standard DVJ, performing the header DVJ led to significantly reduced peak knee flexion angle (Δ = 5.35°; P = .002), knee flexion displacement (Δ = 3.89°; P = .015), hip flexion angle at initial contact (Δ = -2.84°; P = .001), peak trunk flexion angle (Δ = 13.11°; P = .006), and center of mass vertical displacement (Δ = -0.02m; P = .010), and increased peak anterior tibial shear force (Δ = -0.72 N/kg; P = .020), trunk lateral flexion angle at initial contact (Δ = 1.55°; P < .0001), peak trunk lateral flexion angle (Δ = 1.34°; P = .003), knee joint stiffness (Δ = 0.002 N*m/kg/deg; P = .017), and leg stiffness (Δ = 8.46 N/kg/m; P = .046) compared to those in standard DVJs. In addition, individuals' data for these variables were highly and positively correlated between conditions (r = 0.632-0.908; P < .001).

Conclusion

The header DVJ task showed kinetic and kinematic parameters that suggested increased risk of ACL injury as compared with the standard DVJ task.

Clinical Relevance

Athletes may benefit from acquiring the ability to safely perform header DVJs to prevent ACL injury. To simulate real-time competition situations, coaches and athletic trainers should incorporate such dual tasks in ACL injury prevention programs.

Skill-Specific Differences in Equipment-Related Risk Factors for ACL Injury in Male and Female Recreational Skiers

Background

In recreational alpine skiing, the anterior cruciate ligament (ACL) is affected in approximately 50% of serious knee injuries. There are established sex-based and skill-based differences in ACL injury risk, but the potential impact of equipment used (eg, skis, bindings, and boots) has not been evaluated.

Purpose

To evaluate individual and equipment-related risk factors for an ACL injury depending on sex and skill level.

Study Design

Case-control study; Level of evidence, 3.

Methods

This was a retrospective questionnaire-based, case-control study of female and male skiers with and without ACL injuries during 6 winter seasons (from 2014-2015 to 2019-2020). Demographic data, skill level, equipment specifications, risk-taking behavior, and ownership of ski equipment were recorded. Ski geometry (ski length; sidecut radius; and widths of the tip, waist, and tail) was taken from each participant's ski. The standing heights of the front and back part of the ski binding were measured using a digital sliding caliper, and the standing height ratio was calculated. Abrasion of the ski boot sole was also measured at the toe and heel. Participants were divided by sex into less and more skilled skiers.

Results

A total of 1817 recreational skiers participated in this study, of whom 392 (21.6%) sustained an ACL injury. A greater standing height ratio and more abrasion at the toe of the boot sole were associated with increased ACL injury risk in both sexes, independent of the skill level. Riskier behavior increased the injury risk only in male skiers, independent of the skill level, and longer skis increased the injury risk only in less skilled female skiers. Older age, the use of rented/borrowed skis, and more abrasion at the heel of the boot sole were independent risk factors for ACL injury in the more skilled skiers of both sexes.

Conclusion

Individual and equipment-related risk factors for an ACL injury partly differed according to skill level and sex. Consideration of the demonstrated equipment-related factors should be implemented in order to reduce ACL injuries in recreational skiers.

Return to Play and Pattern of Injury After ACL Rupture in a Consecutive Series of Elite UEFA Soccer Players

Background

Anterior cruciate ligament rupture represents a career-threatening injury for professional soccer players.

Purpose

To analyze the pattern of injury, return to play (RTP), and performance of a consecutive series of elite professional soccer players after anterior cruciate ligament reconstruction (ACLR).

Study Design

Case series; Level of evidence, 4.

Methods

We evaluated the medical records of 40 consecutive elite soccer players who underwent ACLR by a single surgeon between September 2018 and May 2022. Patient age, height, weight, body mass index, position, injury history, affected side, RTP time, minutes played per season (MPS), and MPS as a percentage of playable minutes before and after ACLR were retrieved from medical records and from publicly available media-based platforms.

Results

Included were 27 male patients (mean ± SD age at surgery, 23.2 ± 4.3 years; range, 18-34 years). The injury occurred during matches in 24 players (88.9%), with a noncontact mechanism in 22 (91.7%). Meniscal pathology was found in 21 patients (77.8%). Lateral meniscectomy and meniscal repair were performed in 2 (7.4%) and 14 (51.9%) patients, respectively, and medial meniscectomy and meniscal repair were performed in 3 (11.1%) and 13 (48.1%) patients, respectively. A total of 17 players (63.0%) underwent ACLR with bone-patellar tendon-bone autograft and 10 (37.0%) with soft tissue quadriceps tendon. Lateral extra-articular tenodesis was added in 5 patients (18.5%). The overall RTP rate was 92.6% (25 of 27). Two athletes moved to a lower league after surgery. The mean MPS% during the last preinjury season was 56.69% ± 21.71%; this decreased significantly to 29.18% ± 20.6% (P < .001) in the first postoperative season and then increased to 57.76% ± 22.89% and 55.89% ± 25.8% in the second and third postoperative seasons. Two (7.4%) reruptures and 2 (7.4%) failed meniscal repairs were reported.

Conclusion

ACLR in elite UEFA soccer players was associated with a 92.6% rate of RTP and 7.4% rate of reinjury within 6 months after primary surgery. Moreover, 7.4% of soccer players moved to a lower league during the first season after surgery. Age, graft selection, concomitant treatments, and lateral extra-articular tenodesis were not significantly associated with prolonged RTP.

Effect of sprinting velocity on anterior cruciate ligament and knee load during sidestep cutting

The purpose of the study was to investigate the effect of an increase in sprinting velocity on the anterior cruciate ligament (ACL) load, knee joint load, and activation of femoral muscles using the musculoskeletal modeling approach. Fourteen high school male athletes were recruited (age: 17.4 ± 0.7 years, height: 1.75 ± 0.04 m, weight: 73.3 ± 8.94 kg), with the right foot dominant and physical activity level of about 3-4 h per day. The kinematics, kinetics, and co-contraction index (CCI) of the extensors and flexors of the right leg's femoral muscles were calculated. The anterior cruciate ligament load was estimated using the musculoskeletal modeling method. In the results, it was observed that the anterior cruciate ligament load (p < 0.017) increased as sidestep cutting velocity increased, resulting in increased adduction (p < 0.017) and the internal rotation moment of the knee joint. This was significantly higher than when sprinting at a similar velocity. The co-contraction index result, which represents the balanced activation of the femoral extensor and flexor muscles, showed a tendency of decrement with increasing sprinting velocity during sidestep cutting (p < 0.017), whereas no significant differences were observed when running at different sprinting conditions. Therefore, we postulate that factors such as knee joint shear force, extended landing posture with increasing sprinting velocity, internal rotation moment, and femoral muscle activity imbalance influence the increase of anterior cruciate ligament load during a sidestep cutting maneuver.

Risk factors for secondary meniscus tears can be accurately predicted through machine learning, creating a resource for patient education and intervention

PURPOSE

This study sought to develop and internally validate a machine learning model to identify risk factors and quantify overall risk of secondary meniscus injury in a longitudinal cohort after primary ACL reconstruction (ACLR).

METHODS

Patients with new ACL injury between 1990 and 2016 with minimum 2-year follow-up were identified. Records were extensively reviewed to extract demographic, treatment, and diagnosis of new meniscus injury following ACLR. Four candidate machine learning algorithms were evaluated to predict secondary meniscus tears. Performance was assessed through discrimination using area under the receiver operating characteristics curve (AUROC), calibration, and decision curve analysis; interpretability was enhanced utilizing global variable importance plots and partial dependence curves.

RESULTS

A total of 1187 patients underwent ACLR; 139 (11.7%) experienced a secondary meniscus tear at a mean time of 65 months post-op. The best performing model for predicting secondary meniscus tear was the random forest (AUROC = 0.790, 95% CI: 0.785-0.795; calibration intercept = 0.006, 95% CI: 0.005-0.007, calibration slope = 0.961 95% CI: 0.956-0.965, Brier's score = 0.10 95% CI: 0.09-0.12), and all four machine learning algorithms outperformed traditional logistic regression. The following risk factors were identified: shorter time to return to sport (RTS), lower VAS at injury, increased time from injury to surgery, older age at injury, and proximal ACL tear.

CONCLUSION

Machine learning models outperformed traditional prediction models and identified multiple risk factors for secondary meniscus tears after ACLR. Following careful external validation, these models can be deployed to provide real-time quantifiable risk for counseling and timely intervention to help guide patient expectations and possibly improve clinical outcomes.

LEVEL OF EVIDENCE

III.

Video Analysis of 26 Cases of Second ACL Injury Events in Collegiate and Professional Athletes

Background

Significant effort has gone into the identification and quantification of the underlying mechanisms of primary ACL injury. Secondary ACL injury is observed in approximately 1/4 to 1/3 of athletes who return to sport following ACL reconstruction. However, little has been done to evaluate the mechanisms and playing circumstances surrounding these repeat injuries.

Hypothesis/Purpose

The purpose of this study was to characterize the mechanisms of non-contact secondary ACL injuries using video analysis. It was hypothesized that in video recordings of secondary ACL injury, athletes would exhibit greater frontal plane hip and knee angles, but not greater hip and knee flexion, at 66 ms following initial contact (IC) as compared to at IC and 33ms following IC.

Study Design

Cross-Sectional Study.

Methods

Twenty-six video recordings of competitive athletes experiencing secondary ACL ruptures via noncontact mechanisms were analyzed for lower extremity joint kinematics, playing situation, and player attention. Kinematics were assessed at IC as well as 33 ms (1 broadcast frame) and 66 ms (2 broadcast frames) following IC.

Results

Knee flexion and knee frontal plane angles were greater at 66 ms than IC (p ≤ 0.03). Hip, trunk, and ankle frontal plane angles were not greater at 66 ms than IC (p ≥ 0.22). Injuries were distributed between attacking play (n=14) and defending (n=8). Player attention was most commonly focused on the ball (n=12) or an opponent (n=7). A single-leg landing accounted for just over half of the injuries (54%), while a cutting motion accounted for the remainder of the injuries (46%).

Conclusion

Secondary ACL injury was most likely to occur during landing or a sidestep cut with player attention external to their own body. Knee valgus collapse combined with limited hip motion was identified in the majority of secondary injuries.

Level of Evidence

Level IIIb.

The Need To Change Return to Play Testing in Athletes Following ACL Injury: A Theoretical Model

The incidence of knee injuries in sport, particularly involving the ACL, appears to be increasing yearly, especially in younger age athletes. Even more concerning is the frequency of ACL reinjury also appears to be increasing year after year. Improving the objective criteria and testing methods used to determine return to play (RTP) readiness following ACL surgery is one aspect of the rehabilitation process that can significantly help in reducing reinjury rates. Currently, the majority of clinicians are still using post operative time frames as their number one criterion for clearance to RTP. This flawed method demonstrates an inadequate reflection of the true unpredictable, dynamic environment athletes are returning to participate in. In our clinical experience, objective testing to allow for clearance to sport participation following an ACL injury should incorporate neurocognitive and reactive testing due to the nature of the injury typically occurs because of failed control of unanticipated reactive movements. The purpose of this manuscript is to share a neurocognitive testing sequence we currently employ consisting of 8 tests in 3 categories: Blazepod tests, reactive shuttle run tests, and reactive hop tests. The use of a more dynamic reactive testing battery may decrease the reinjury rates when an athlete is cleared for participation by measuring readiness in chaotic circumstances that are more truly reflective of the sporting environment the athlete is working to return to and in the process give them a greater sense of confidence.

A systematic review of transphyseal ACL reconstruction in children and adolescents: comparing the transtibial and independent femoral tunnel drilling techniques

PURPOSE

Aim of this systematic review was to analyze the outcome after transphyseal ACL reconstruction in children and adolescents regarding the femoral drilling technique.

METHODS

A systematic literature search was carried out in various databases on studies on transphyseal ACL reconstruction in children and adolescents. The literature search was limited to the last 20 years. Primary outcome criterion was the failure rate. Secondary outcome criteria were growth disturbances such as leg length discrepancies or deformities and clinical scores. The present study was registered prospectively ( www.crd.york.ac.uk/PROSPERO ; CRD42022345964).

RESULTS

A total of 22 retrospective or prospective case series (level 4 evidence) were identified that reported on transphyseal ACL reconstruction in children and adolescents. The overall failure/rupture rate after transphyseal ACL reconstruction was 11.0%. The overall ACL rupture rate of the contralateral side was 9.7%. No statistical significant difference in the failure rates between independent and transtibial drilling techniques could be detected ((p = 0.76/p = 0.28)). Furthermore no statistical significant differences in the rate of reported growth disturbances between independent and transtibial drilling techniques were shown (p = 0.15). The reported clinical scores at follow-up (mean follow-up 5.05 years) revealed good to very good results.

CONCLUSION

This systematic review demonstrates that children and adolescents have a relatively high failure rate after transpyseal ACL reconstruction without any statistically significant differences between independent or transtibial drilling techniques regarding reruptur rates or the rate of growth disturbances. The results of this systematic review warrant a comparison of both techniques for femoral tunnel drilling in a controlled randomized trial.

Difference in Bioimpedance Across the Knee in Un-Injured Young Adults

Background

Knee injuries induce swelling and resolution of swelling may be a useful factor in identifying states of healing and time to return to sports activities. Recent work has suggested that bioimpedance can provide an objective measure of swelling following total knee arthroplasty (TKA) and therefore may also provide guidance for clinical decision-making following knee injury. This study measures knee bioimpedance in young, active people to help define baseline variability and factors that influence limb to limb differences.

Methods

Bioimpedance was measured via sensors placed at the foot/ankle and thigh, in positions similar to those suggested for monitoring post-TKA swelling. Initial tests were performed to verify method repeatability, then bioimpedance was measured in a convenience sample of 78 subjects (median age 21yrs). The influence of age, BMI, thigh circumference, and knee function (KOOS-JR) on the impedance measures and difference in impedance between the subject's knees were examined using a generalized multivariable linear regression.

Results

The repeatability study measurements were highly consistent with a COV of 1.5% for resistance and an ICC of 97.9%. Women exhibited significantly larger dominant limb impedance and larger limb to limb difference in impedance than men. Regression analysis indicated that subject sex and BMI significantly influenced bioimpedance but joint score and age did not. The limb to limb differences in impedance were small on average (<5%), with larger magnitudes of difference associated with female sex, lower knee function scores, and larger limb to limb differences in thigh circumference.

Conclusion

Bioimpedance measurements across right and left knees of healthy young people were similar, supporting use of bioimpedance measures from a patient's uninjured knee as a benchmark to monitor healing of a contralateral injured knee. Future work should focus on understanding how knee function scores and bioimpedance are related, and further explore how sex and side to side anatomic differences impact the measurement. Level of Evidence: IV.

The posterior cruciate ligament-posterior femoral cortex angle: a reliable and accurate MRI method to quantify the buckling phenomenon of the PCL in ACL-deficient knees

PURPOSE

The aim was to validate a new MRI method to measure the buckling phenomenon of the PCL, representative of anterior tibial translation, by comparing its reliability and accuracy to identify anterior cruciate ligament (ACL)-deficient knees with existing methods.

METHODS

Patients were selected retrospectively and separated into a group of primary ACL injuries and ACL-intact knees. Exclusion criteria were: skeletal immaturity, PCL or a concomitant collateral ligament injury, signs of osteoarthritis (> 1 Kellgren and Lawrence score), tibial plateau fracture, previous ACL reconstruction or displaced meniscal bucket handle tear. The assessment of the curvature of the anterolateral bundle of the PCL was performed on T2 sagittal MRI slices according to 3 methods: (1) the PCL angle (PCLA), (2) the PCL inclination angle (PCLIA) and (3) a new method: the PCL-posterior cortex angle (PCL-PCA), representing the angle between the vertical part of the PCL-ALB and the posterior diaphyseal cortex of the femur. For each method, the inter- and intra-observer reliability was measured. The ability to discriminate both ACL-deficient and ACL-intact knees was evaluated using ROC curves.

RESULTS

Twenty-four patients were included in each group. Intra-observer reliability was excellent for all 3 methods (ICCs > 0.90). Inter-observer reliability was excellent for the PCL-PCA (ICC > 0.90) and good for the PCLA and the PCLIA (ICCs between 0.75 and 0.90). The PCL-PCA had the highest precision (lowest standard error of measurement: 2.7°). It yielded an excellent discrimination between the ACL and CTL groups (AUC 0.80 [0.67-0.93]) with the highest sensitivity (71% [52.8-89.2]) and specificity (88% [75-100]) for a positive threshold when the angle was ≤ 22.7°. The PCLA and PCLIA methods led to acceptable discrimination and lower sensitivities and specificities (PCLA: AUC 0.71, sensitivity 63%, specificity 79%, threshold ≤ 117.9°; PCLIA: AUC 0.62, sensitivity 50%, specificity 83%, threshold ≤ 21.4°).

CONCLUSION

In comparison with previously described methods, the PCL-PCA was the most reliable and accurate method to measure the PCL buckling phenomenon on MRI in anterior cruciate ligament (ACL)-deficient knees. It offers an easy and objective method for the follow-up of ACL-injured patients and can therefore be recommended for routine use.

LEVEL OF EVIDENCE

IV.

Evaluation of a Smart Knee Brace for Range of Motion and Velocity Monitoring during Rehabilitation Exercises and an Exergame

Anterior cruciate ligament (ACL) injuries often require a lengthy duration of rehabilitation for patients to return to their prior level of function. Adherence to rehabilitation during this prolonged period can be subpar due to the treatment duration and poor adherence to home exercises. This work evaluates whether a smart instrumented knee brace system is capable of monitoring knee range of motion and velocity during a series of common knee rehabilitation exercises and an exergame. A total of 15 healthy participants completed a series of common knee rehabilitation exercises and played an exergame while wearing a smart instrumented knee brace. The range of motion (ROM) and velocity of the knee recorded by the knee brace was compared to a reference optoelectronic system. The results show good agreement between the knee brace system and the reference system for all exercises performed. Participants were able to quickly learn how to play the exergame and scored well within the game. The system investigated in this study has the potential to allow rehabilitation to occur outside of the clinic with the use of remote monitoring, and improve adherence and outcomes through the use of an exergame.

Correlations of strength, proprioception, and tactile sensation to return-to-sports readiness among patients with anterior cruciate ligament reconstruction

Objectives: Anterior cruciate ligament reconstruction (ACLR) is the most common surgery for anterior cruciate ligament (ACL) injuries, and the relationships between patients' return to sports (RTS) readiness and different physical functions are inconclusive among patients with ACLR. This study aimed to investigate the correlations of strength, proprioception, and tactile sensation to the RTS readiness among patients with ACLR. Methods: Forty-two participants who received ACLR for at least 6 months were enrolled in this study. Their strength, proprioception, and tactile sensation were tested, and their RTS readiness was measured with the Knee Santy Athletic Return to Sports (K-STARTS) test, which consists of a psychological scale [Anterior Cruciate Ligament Return to Sports after Injury scale (ACL-RSI)] and seven functional tests. Partial correlations were used to determine their correlations while controlling for covariates (age, height, weight, and postoperative duration), and factor analysis and multivariable linear regressions were used to determine the degrees of correlation. Results: Knee extension strength was moderately correlated with K-STARTS total, ACL-RSI, and functional scores. Knee flexion strength, knee flexion and extension proprioception, and tactile sensation at the fifth metatarsal were moderately correlated with K-STARTS total and functional scores. Strength has higher levels of correlation with functional scores than proprioception. Conclusion: Rehabilitation to promote muscle strength, proprioception and tactile sensation should be performed among patients with ACLR, muscle strength has the highest priority, followed by proprioception, with tactile sensation making the least contribution.

Analysis of limb kinetic asymmetry during a drop vertical jump in adolescents post anterior cruciate ligament reconstruction

BACKGROUND

Limb asymmetry after ACL reconstruction is often cited as a risk factor for ACL reinjury. We assessed ground reaction forces on each limb during a drop vertical jump, and compared kinetic symmetry between limbs in adolescents post-ACL reconstruction versus healthy controls.

METHODS

Forty-four participants who underwent an ACL reconstruction (16 male/28 female, mean age 16.1 ± 1.5, mean 7.3 ± 0.9 months post-ACL reconstruction) and 34 controls (20 male/14 female, mean age 14.9 ± 1.1) completed a drop vertical jump captured on a Vicon system and Bertec force plates. Kinetic variables were calculated individually for each limb. Inter-limb asymmetry was calculated as an index between each limb (involved versus uninvolved for the ACL reconstruction group, and left versus right for controls), and was compared between groups using independent t-tests.

FINDINGS

Asymmetry was significantly more pronounced in the ACL reconstruction group versus the controls for peak contact ground reaction force (11.6% vs 4.4%, p = 0.009), eccentric impulse (8.8% vs 3.8%, p = 0.009), eccentric mean force (8.0% vs 3.4%, p = 0.006), concentric peak ground reaction force (4.1% vs 0.8%, p = 0.003), concentric impulse (5.1% vs 1.1%, p = 0.001), and peak landing ground reaction force (12.7% vs 1.7%, p < 0.001).

INTERPRETATION

Limb kinetic asymmetry during a drop vertical jump was more pronounced in adolescents post-ACL reconstruction versus controls for both eccentric- and concentric-phase variables, which may indicate the use of compensatory strategies to offload the post-operative limb. Targeted interventions to produce more symmetric loading and unloading during jumping tasks should be developed, tested, and monitored to determine the impact on rehabilitation programs, return-to-sport evaluations, and injury prevention outcomes.