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

Bench to Bedside: A Multidisciplinary Approach toward the Unknowns after ACL Injuries to Drive Individual Success

ACL injury and surgery are increasing in prevalence. Several challenges exist that can be obstacles to an individual achieving success after ACL surgery. A knowledge of these risk factors alongside a multidisciplinary collaborative team approach can result in a greater likelihood of achieving individual success after ACL surgery.

Early Superimposed NMES Training is Effective to Improve Strength and Function Following ACL Reconstruction with Hamstring Graft regardless of Tendon Regeneration

The study aimed at investigating the effects of neuromuscular electrical stimulation superimposed on functional exercises (NMES+) early after anterior cruciate ligament reconstruction (ACLr) with hamstring graft, on muscle strength, knee function, and morphology of thigh muscles and harvested tendons. Thirty-four participants were randomly allocated to either NMES+ group, who received standard rehabilitation with additional NMES of knee flexor and extensor muscles, superimposed on functional movements, or to a control group, who received no additional training (NAT) to traditional rehabilitation. Participants were assessed 15 (T1), 30 (T2), 60 (T3), 90 (T4) and at a mean of 380 days (T5) after ACLr. Knee strength of flexors and extensors was measured at T3, T4 and T5. Lower limb loading asymmetry was measured during a sit-to-stand-to-sit movement at T1, T2, T3, T4 and T5, and a countermovement-jump at T4 and T5. An MRI was performed at T5 to assess morphology of thigh muscles and regeneration of the harvested tendons. NMES+ showed higher muscle strength for the hamstrings (T4, T5) and the quadriceps (T3, T4, T5), higher loading symmetry during stand-to-sit (T2, T3, T4, T5), sit-to-stand (T3, T4) and countermovement-jump (T5) than NAT. No differences were found between-groups for morphology of muscles and tendons, nor in regeneration of harvested tendons. NMES+ early after ACLr with hamstring graft improves muscle strength and knee function in the short- and long-term after surgery, regardless of tendon regeneration.

The effect of gracilis tendon harvesting in addition to semitendinosus tendon harvesting on knee extensor and flexor strength after anterior cruciate ligament reconstruction

INTRODUCTION

Anterior cruciate ligament (ACL) reconstruction using hamstring tendons may involve harvesting of the gracilis tendon in addition to the semitendinosus tendon (ST) depending on the size of the ST graft. However, the effect of gracilis harvesting in addition to ST harvesting on muscle strength, such as the hamstring-to-quadriceps (HQ) ratio, remains unclear. Hence, this study aimed to investigate the effect of gracilis harvesting on subsequent knee muscle strength.

MATERIALS AND METHODS

Eighty-two patients who underwent ACL reconstruction were included in this retrospective study. They were divided into the following two groups depending on the tendon graft used for ACL reconstruction: the ST group (41 patients) and the semitendinosus tendon/gracilis tendon (STG) group (41 patients). The isokinetic peak torque of the knee extensor and flexor was measured using a BIODEX dynamometer at a velocity of 60°/s and 180°/s, respectively, 3 and 6 months after ACL reconstruction. The groups were compared in terms of the limb symmetry index (LSI) and HQ ratio.

RESULTS

The significant difference in the knee flexor of the LSI at 6 months after ACL reconstruction was as follows: ST group, 120.3 ± 28.3 vs STG group, 105.6 ± 19.0 (p < 0.01) at 60°/s and ST group, 122.9 ± 35.2 vs STG group, 106.2 ± 24.6 (p = 0.02) at 180°/s. There were significant differences in the HQ ratio at 180°/s as follows: ST group, 0.67 ± 0.15 vs STG group, 0.60 ± 0.13 (p < 0.01) at 3 months and ST group, 0.67 ± 0.13 vs STG group, and 0.59 ± 0.12 (p < 0.01) at 6 months after ACL reconstruction.

CONCLUSIONS

Gracilis tendon harvesting may contribute to a decrease in knee flexor strength and HQ ratio with fast contraction. Thus, the need for gracilis tendon harvesting in ACL reconstruction should be carefully considered.

LEVEL OF EVIDENCE

III.

Association of Quadriceps Strength Symmetry and Surgical Status With Clinical Osteoarthritis Five Years After Anterior Cruciate Ligament Rupture

OBJECTIVE

The objective of this study was to examine the association of quadriceps strength symmetry and surgical status (anterior cruciate ligament [ACL] reconstruction or nonoperative management) with early clinical knee osteoarthritis (OA) 5 years after ACL injury or reconstruction.

METHODS

In total, 204 of 300 athletes were analyzed 5 years after ACL injury or reconstruction. Quadriceps strength was measured and reported as a limb symmetry index. We identified participants with early clinical knee OA using the criteria that 2 of 4 Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales score ≤85%. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) using logistic regression and adjusted for age, sex, meniscal injury, and body mass index to examine the associations of quadriceps strength and surgical status with clinical knee OA.

RESULTS

In all, 21% of participants met the KOOS criteria for clinical knee OA. For every 1% increase in quadriceps limb symmetry index, there was a 4% lower odds of clinical OA (adjusted OR [OR_adj ] 0.96 [95% CI 0.93-0.99]) at 5 years. Surgical status was not associated with clinical knee OA (OR_adj 0.58 [95% CI 0.23-1.50]).

CONCLUSION

More symmetric quadriceps strength, but not surgical status, 5 years after ACL injury or reconstruction was associated with lower odds of clinical knee OA.

Suture tape reinforcement of hamstring tendon graft reduces postoperative knee laxity after primary ACL reconstruction

Purpose

To evaluate and compare subjective and objective knee outcomes following hamstring tendon (HT) and quadriceps tendon (QT) anterior cruciate ligament reconstruction (ACLR) with or without suture tape (ST) reinforcement. It was hypothesized that the addition of an intra-articular synthetic augmentation with a ST would reduce postoperative knee laxity and graft ruptures after ACLR.

Methods

A 1:1 matched-cohort comparison of patients who underwent HT and QT autograft ACLR with or without ST reinforcement was performed. Patients with ST reinforcement were consecutively assigned to the study groups until a number of 20 in each group was achieved. Medical records were reviewed for demographic characteristics and additional injuries. Laxity measurements with KT-1000, strength measurements and physical examination findings were collected both preoperatively and at 6 months and patient reported outcome (PRO) scores were collected both preoperatively and at 12 months, and comparison was made HT vs HT + ST and QT vs QT + ST. Reoperations and re-ruptures were recorded during the 24-month follow-up period.

Results

Overall, 80 patients who underwent ACLR were included. Patients with HT + ST had significant less laxity postoperatively compared to HT at 6 months, 1.9 vs 0.8 mm, p < 0.05. No differences were found between the QT and QT + ST group. At 6 weeks patients treated with ST, both QT and HT, had a significant deficit in flexion compared to those without ST. However, this resolved at 6 months. There were no significant differences between HT + ST vs HT, or QT + ST vs QT, regarding postoperative PROs or strength measurements. Furthermore, the incidence of subsequent surgery and graft rupture was not significantly different between the groups.

Conclusion

ACLR with HT + ST reduces laxity at 6 months compared to ACLR without ST, a difference not seen when ACLR was performed using QT with or without ST. No other differences were seen between the two techniques comparing subjective and objective findings.

Level of evidence

Level III.

Characteristics of Complex Systems in Sports Injury Rehabilitation: Examples and Implications for Practice

Complex systems are open systems consisting of many components that can interact among themselves and the environment. New forms of behaviours and patterns often emerge as a result. There is a growing recognition that most sporting environments are complex adaptive systems. This acknowledgement extends to sports injury and is reflected in the individual responses of athletes to both injury and rehabilitation protocols. Consequently, practitioners involved in return to sport decision making (RTS) are encouraged to view return to sport decisions through the complex systems lens to improve decision-making in rehabilitation. It is important to clarify the characteristics of this theoretical framework and provide concrete examples to which practitioners can easily relate. This review builds on previous literature by providing an overview of the hallmark features of complex systems and their relevance to RTS research and daily practice. An example of how characteristics of complex systems are exhibited is provided through a case of anterior cruciate ligament injury rehabilitation. Alternative forms of scientific inquiry, such as the use of computational and simulation-based techniques, are also discussed-to move the complex systems approach from the theoretical to the practical level.

Knee strength symmetry at 4 months is associated with criteria and rates of return to sport after anterior cruciate ligament reconstruction

BACKGROUND

Strength limb symmetry index (LSI) is a useful criterion to help in return-to-sport performance (RTP) after anterior cruciate ligament reconstruction (ACLR).

OBJECTIVES

We aimed to assess whether knee extensor and flexor LSI values at 4 months after ACLR are associated with those recommended at 8 months after ACLR for RTP (80%, 85% and 90%) and with successful RTP after 2 years.

METHODS

This was prospective cohort study of 113 participants who underwent primary ACLR. Personal factors such as demographic and sport information, injury and surgery characteristics were collected at 6 weeks after surgery. Isokinetic strength LSI (60°/s) was calculated at 4 months (LSI[4m]) and 8 months (LSI[8m]) for knee extensors (Q-LSI) and flexors (H-LSI). Participants were followed at 2 years after ACLR to determine their self-reported RTP. Multiple linear regression analysis was used to determine associations between personal factors and LSI at 4 and 8 months. Associations between passing the optimal cut-off thresholds and RTP were tested with chi-square tests and odds ratios (ORs) with effect sizes (ES).

RESULTS

Among the 113 participants (mean age 25.2 [SD 9.7] years; 42% females), extended tourniquet time and lower level of pre-injury sport were associated with lower Q-LSI[4m] and H-LSI[4m]. Bone-patellar tendon-bone graft was associated with lower Q-LSI[4m] and Q-LSI[8m], and older age was associated with lower Q-LSI[4m]. For knee extensors, Q-LSI[4m] >59% was associated with Q-LSI[8m] >80% (OR= 31.50, p <0.001, large ES) and increased odds of successful RTP (60% vs 31%, OR= 3.45, p= 0.003, medium ES). For knee flexors, H-LSI[4m] >72% was associated with H-LSI[8m] >90% (OR= 6.03, p <0.001, large ES) and increased odds of successful RTP (53% vs 23%, OR= 3.76, p= 0.013, small-to-medium ES).

CONCLUSIONS

After primary ACLR, 4-month post-operative strength symmetry was negatively associated with age, pre-injury sport and tourniquet time and bone-patellar tendon-bone graft. Four-month post-operative LSI was associated with 8-month post-operative LSI, and Q-LSI[4m] >59% or H-LSI[4m] >72% was associated with increased RTP rates after 2 years. CLINICALTRIALS.GOV: : NCT04071912.

Single leg vertical jump performance identifies knee function deficits at return to sport after ACL reconstruction in male athletes

Objectives

Vertical jump performance (height) is a more representative metric for knee function than horizontal hop performance (distance) in healthy individuals. It is not known what the biomechanical status of athletes after anterior cruciate ligament (ACL) reconstruction (ACLR) is at the time they are cleared to return to sport (RTS) or whether vertical performance metrics better evaluate knee function.

Methods

Standard marker-based motion capture and electromyography (EMG) were collected from 26 male athletes cleared to RTS after ACLR and 22 control healthy subjects during single leg vertical jumps (SLJ) and single leg drop jumps (SLDJ). Performance outcomes, jump height and the Reactive Strength Index, were calculated. Sagittal plane kinematics, joint moments and joint work were obtained using inverse dynamics and lower limb muscle forces were computed using an EMG-constrained musculoskeletal model. Muscle contribution was calculated as a percentage of the impulse of all muscle forces in the model. Between-limb and between-group differences were explored using mixed models analyses.

Results

Jump performance, assessed by jump height and Reactive Strength Index, was significantly lower in the involved than the uninvolved limb and controls, with large effect sizes. For the ACLR group, jump height limb symmetry index was 83% and 77% during the SLJ and SLDJ, respectively. Work generation was significantly less in the involved knee compared to uninvolved limb and controls during the SLJ (p<0.001; d=1.19; p=0.003, d=0.91, respectively) and during the SLDJ (p<0.001; d=1.54; p=0.002, d=1.05, respectively). Hamstrings muscle contribution was greater in the involved compared to the uninvolved limb and controls, whereas soleus contribution was lower in the involved limb compared to controls.

Conclusions

During vertical jumps, male athletes after ACLR at RTS still exhibit knee biomechanical deficits, despite symmetry in horizontal functional performance and strength tests. Vertical performance metrics like jump height and RSI can better identify interlimb asymmetries than the more commonly used hop distance and should be included in the testing battery for the RTS.

Symmetry in Triple Hop Distance Hides Asymmetries in Knee Function After ACL Reconstruction in Athletes at Return to Sports

BACKGROUND

After anterior cruciate ligament reconstruction (ACLR), a battery of strength and hop tests is frequently used to determine the readiness of an athlete to successfully return to sports. However, the anterior cruciate ligament reinjury rate remains alarmingly high.

PURPOSE

To evaluate the lower limb function of athletes after ACLR at the time when they had been cleared to return to sports (RTS). We aimed to evaluate if passing discharge criteria ensures restoration of normal lower limb biomechanics in terms of kinematics, kinetics, work, and percentage work contribution during a triple hop for distance.

STUDY DESIGN

Controlled laboratory study.

METHODS

Integrated 3-dimensional motion analysis was performed in 24 male athletes after ACLR when cleared to RTS and 23 healthy male controls during the triple-hop test. The criteria for RTS were (1) clearance by the surgeon and the physical therapist, (2) completion of a sports-specific on-field rehabilitation program, and (3) limb symmetry index >90% after quadriceps strength and hop battery tests. Lower limb and trunk kinematics, as well as knee joint moments and work, were calculated. Between-limb differences (within athletes after ACLR) and between-group differences (between ACLR and control groups) were evaluated using mixed linear models.

RESULTS

Although achieving 97% limb symmetry in distance hopped and displaying almost 80% symmetry for knee work absorption in the second rebound and third landing, the ACLR cohorts demonstrated only 51% and 66% limb symmetry for knee work generation in the first and second rebound phases, respectively. During both work generation phases of the triple hop, the relative contribution of the involved knee was significantly smaller, with a prominent compensation from the hip joint (P < .001, for all phases) as compared with the uninvolved limb and the controls. In addition, patients deployed a whole body compensatory strategy to account for the between-limb differences in knee function, mainly at the hip, pelvis, and trunk.

CONCLUSION

Symmetry in the triple hop for distance masked important deficits in the knee joint work. These differences were more prominent during work generation (concentric-propulsive) than work absorption (eccentric-landing).

CLINICAL RELEVANCE

Symmetry in hop distance during the triple hop test masked significant asymmetries in knee function after ACLR and might not be the appropriate outcome to use as a discharge criterion. Differences between limbs in athletes after ACLR were more prominent during the power generation than the absorption phase.

RetroBRACE: clinical, socioeconomic and functional-biomechanical outcomes 2 years after ACL repair and InternalBrace augmentation in comparison to ACL reconstruction and healthy controls-experimental protocol of a non-randomised single-centre comparative study

INTRODUCTION

Despite good clinical outcomes reported in the literature, to date, scientific evidence for the functional and biomechanical benefit of primary anterior cruciate ligament (ACL) repair with augmentation is scarce. We present an experimental protocol for a detailed multimodal (clinical, socioeconomic, functional and biomechanical) comparative study in patients after primary ACL repair and InternalBrace augmentation, patients after ACL reconstruction and healthy controls.

METHODS AND ANALYSIS

In this non-randomised single-centre comparative study with prospective data collection with three arms (patients 2 years after ACL repair and InternalBrace augmentation; patients 2 years after ACL reconstruction using hamstring autografts; and healthy controls), 30 participants per study arm will be included. The study is designed as non-inferiority study with three arms. Required sample size was estimated based on data reported in the literature on muscle strength, proprioception and balance parameters, resulting in at least 28 participants per group. Outcome parameters include patient-reported outcome measures (EQ-5D-5L, Tegner Activity Scale, Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee and ACL-Return to Sports Injury Scale), socio-economic parameters, anterior tibial translation, range of motion and functional-biomechanical data of the lower extremities. Functional-biomechanical parameters include proprioception, isokinetic muscle strength, single-leg balance, walking, running and single-leg hops with additional lower extremity 3D joint kinematics and kinetics and muscle activity. These parameters will be compared between limbs in patients, between groups and to the current literature.

ETHICS AND DISSEMINATION

The results of this study will be disseminated through peer-reviewed publications and presentations at national and international conferences. Ethical approval was obtained by the regional ethics board (Ethics Committee Northwest Switzerland EKNZ 2020-00551), and the study is registered at clinicaltrials.gov.Trial registration numberNCT04429165.

Predictors of Graft Failure in Young Active Patients Undergoing Hamstring Autograft Anterior Cruciate Ligament Reconstruction With or Without a Lateral Extra-articular Tenodesis: The Stability Experience

BACKGROUND

Anterior cruciate ligament (ACL) reconstruction (ACLR) has higher failure rates in young active patients returning to sports as compared with older, less active individuals. Augmentation of ACLR with an anterolateral procedure has been shown to reduce failure rates; however, indications for this procedure have yet to be clearly defined.

PURPOSE/HYPOTHESIS

The purpose of this study was to identify predictors of ACL graft failure in high-risk patients and determine key indications for when hamstring ACLR should be augmented by a lateral extra-articular tenodesis (LET). We hypothesized that different preoperative characteristics and surgical variables may be associated with graft failure characterized by asymmetric pivot shift and graft rupture.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were obtained from the Stability 1 Study, a multicenter randomized controlled trial of young active patients undergoing autologous hamstring ACLR with or without a LET. We performed 2 multivariable logistic regression analyses, with asymmetric pivot shift and graft rupture as the dependent variables. The following were included as predictors: LET, age, sex, graft diameter, tear chronicity, preoperative high-grade knee laxity, preoperative hyperextension on the contralateral side, medial meniscal repair/excision, lateral meniscal repair/excision, posterior tibial slope angle, and return-to-sports exposure time and level.

RESULTS

Of the 618 patients in the Stability 1 Study, 568 with a mean age of 18.8 years (292 female; 51.4%) were included in this analysis. Asymmetric pivot shift occurred in 152 (26.8%) and graft rupture in 43 (7.6%). The addition of a LET (odds ratio [OR], 0.56; 95% CI, 0.37-0.83) and increased graft diameter (OR, 0.62; 95% CI, 0.44-0.87) were significantly associated with lower odds of asymmetric pivot shift. The addition of a LET (OR, 0.40; 95% CI, 0.18-0.91) and older age (OR, 0.83; 95% CI, 0.72-0.96) significantly reduced the odds of graft rupture, while greater tibial slope (OR, 1.15; 95% CI, 1.01-1.32), preoperative high-grade knee laxity (OR, 3.27; 95% CI, 1.45-7.41), and greater exposure time to sport (ie, earlier return to sport) (OR, 1.18; 95% CI, 1.08-1.29) were significantly associated with greater odds of rupture.

CONCLUSION

The addition of a LET and larger graft diameter were significantly associated with reduced odds of asymmetric pivot shift. Adding a LET was protective of graft rupture, while younger age, greater posterior tibial slope, high-grade knee laxity, and earlier return to sport were associated with increased odds of graft rupture. Orthopaedic surgeons should consider supplementing hamstring autograft ACLR with a LET in young active patients with morphological characteristics that make them at high risk of reinjury.

Training potential of visual feedback to improve dynamic postural stability

BACKGROUND

Deficits in single-limb dynamic postural stability are predictive for reinjuries of the lower extremities, which are very common in sports. The use of force plates has become increasingly common to measure dynamic postural stability. Visual feedback on force-plate based stability outcomes have been shown to improve performance during static tasks. A similar effect might occur in dynamic tasks. Since dynamic tasks are generally more specific for performance during sport, this could have important training implications.

RESEARCH QUESTION

What is the effect of visual feedback on postural stability outcomes during a dynamic stability task?

METHODS

Twenty-four healthy participants participated in this study. During measurements, subjects were standing on one leg while mediolateral position-controlled platform perturbations were used to evoke and measure balance responses. All participants were tested under three conditions: with visual Time-to-Stability (TTS) feedback, with visual Center of Pressure speed (COPs) feedback and without visual feedback. TTS and COPs outcomes were calculated over a 5-second time window after each perturbation and were compared between conditions.

RESULTS

Visual feedback resulted in significantly better stability outcomes during the dynamic stability task. TTS feedback resulted in a task-specific feedback learning effect, as it resulted in a gradual improvement of TTS scores (from 1.09 s to 0.68 s; -38%) in absence of a significant change in COPs. COPs feedback resulted in a non-specific attention effect, directly improving COPs (without feedback 5.26 cm/s with feedback 4.95 cm/s; -6%) and TTS scores (without feedback 1.47 s with feedback 0.99 s; -39%) in absence of an apparent further improvement over time.

SIGNIFICANCE

The ability to improve performance of dynamic stability tasks when visual feedback is added could have substantial impact for rehabilitation. Possibly, the use of visual feedback during stability training could improve the effectiveness of postural stability training.

Reinjury Rates in Adolescent Patients 2 Years Following ACL Reconstruction

BACKGROUND

Sports injuries have increased dramatically in the pediatric and adolescent population. Return-to-sport testing and criteria are increasingly utilized, however, the guidelines for return to play in adolescents are unclear. The purpose of this study was to compare strength and function at the time of the return-to-sport progression to those with and without a failed anterior cruciate ligament reconstruction (ACLR).

METHODS

A total of 105 adolescent patients with primary ACLR were assessed at the time of return to sport. We identified graft failures/contralateral injury through medical records, clinic visits, or phone interviews at minimum 2 years of postsurgical follow-up. All patients completed bilateral isokinetic strength tests of the knee extensor/flexor groups and hop tests. Strength was expressed as torque-normalized-to-mass (Nm/kg), and limb-symmetry-index was expressed as a percentage of the uninvolved limb's strength. All patients completed outcome surveys. The χ2 analysis was used to compare failures between sexes and graft types. Independent sample t tests were used to compare knee extensor/flexor strength, symmetry, and hop test results between patients with and without secondary anterior cruciate ligament (ACL) injury. One-way analysis of variance was used to compare knee extensor/flexor strength and symmetry, hop test, and survey results between those (1) without secondary injury, (2) ACLR graft failure, and (3) contralateral ACL injury.

RESULTS

A total of 100 of 105 patients (95.2%) were included with 4±1.2 years of follow-up, with 28 (28%) sustaining subsequent injury (12% graft, 16% contralateral). Patients with graft failure demonstrated (1) stronger quadriceps strength (2.00±0.46 Nm/kg) compared with those with contralateral ACL injury (1.58±0.35 Nm/kg, P=0.039) and patients that did not have a secondary injury (1.58±0.44 Nm/kg, P=0.007), (2) greater quadriceps strength symmetry (85.7±0.11.2%) compared with patients without secondary injury ACL (72.9±17.9%, P=0.046), (3) a greater proportion of hamstring grafts compared with those without reinjury (P=0.028).

CONCLUSIONS

Adolescent patients who sustained ACLR graft failure had greater and more symmetric quadriceps strength at the time of return to sport compared with patients with no secondary injury. Objective measures of quadriceps strength at the time of the return-to-sport progression may not solely identify individuals that have a secondary ACL injury.

STUDY DESIGN

Level IV-retrospective cohort study.

Fear of Movement and Reinjury in Sports Medicine: Relevance for Rehabilitation and Return to Sport

Athletes are defined by their ability to move and are often accustomed to pain as it relates to their sports and exercise regime. The forced movement restriction and pain associated with an acute or overuse injury has a profound effect not only on their physical abilities but also on their psychological well-being and social context. With the goal of returning to sport, the rehabilitation focus historically has been on recovery of physical attributes, but more recent research is addressing the psychological factors. This Perspective proposes that-according to the current evidence in sports medicine-the fear that affects choice of treatment, rehabilitation, and return to sports is intertwined with physical capacity and recovery of function. Past injury is also 1 of the main risk factors for a sports injury; therefore, fear of reinjury is not irrational. For an athlete, the fear related to a sports injury encompasses the fear of reinjury along with fear of not being able to return to the sport at their highest performance level-and the fear of having lifelong debilitating pain and symptoms. This Perspective reviews the evidence for the influence of fear of movement and reinjury on choice of treatment, rehabilitation, and return to sport and provides suggestions on how to address this fear during the continuum of treatment and return to sports.

Angle specific analysis of hamstrings and quadriceps isokinetic torque identify residual deficits in soccer players following ACL reconstruction: a longitudinal investigation

 Analysing the isokinetic curve is important following ACL reconstruction as there may be deficits in torque production at specific points throughout the range of motion. We examined isokinetic (60°.s-1) torque-angle characteristics in 27 male soccer players (24.5 ± 3.9 years) at 3 time-points (17 ± 5; 25 ± 6; and 34 ± 7 weeks post-surgery). Extracted data included knee flexor and extensor peak torque, conventional hamstrings: quadriceps (H/Q) ratio, and angle-specific torque using Statistical Parametric Mapping (SPM). There were significant involved limb increases in extension peak torque at each assessment (p<0.001); however, asymmetry favouring the un-involved limb was observed (p<0.01). Flexion peak torque was greater on the un-involved limb at assessments 1 and 2 only (p<0.05). The angle of peak torque was not significantly different at individual time-points or within-limbs across the 3 assessments. SPM revealed involved limb angle-specific reductions in extension torque across the full range of motion at time-points 1 and 2 (p<0.001) but only in angles [51-80°] at assessment 3 (p<0.05). Between limb H/Q angle differences [33-45°] were shown at assessments 2 and 3. The ratio ranged from 1.60-0.74 depending on the angle tested. Angle-specific moment curves are useful for monitoring patterns of strength development during rehabilitation.

A Compound Hop Index for Assessing Soccer Players' Performance

Athletes regularly have to pass a series of tests, among which one of the most frequently used functional performance measures are single-leg hop tests. As the collected individual results of tests constitute a large amount of data, strategies to decrease the amount of data without reducing the number of performed tests are being searched for. Therefore, the study aimed to present an effective method to reduce the hop-test battery data to a single score, namely, the Compound Hop Index (CHI) in the example of a soccer team. A male, first-league soccer team performed a battery of commonly used single-leg hop tests, including single hop and triple hop for distance tests and the six-meter timed hop test. Gathered data, including Limb Symmetry Indexes of the three tests, normalized to body height for the single- and triple-hop-tests distance separately for right and left legs, and the time of the six-meter timed hop test separately for right and left legs were standardized to z-scores. Consecutively, the z-scores were averaged and formed CHI. The developed CHI represents a novel score derived from the average of z-scores that significantly reduces, clarifies, and organizes the hop performance-measures data.

Return to Sport After Medial Patellofemoral Ligament Reconstruction: A Systematic Review and Meta-analysis

BACKGROUND

Patellar instability is frequently encountered in the athletic population. Medial patellofemoral ligament (MPFL) reconstruction is a common strategy to treat recurrent patellar dislocation and demonstrates good clinical outcomes.

PURPOSE/HYPOTHESIS

The purpose was to examine return to sport after MPFL reconstruction for patellar instability. We hypothesized that patients would resume athletic activity at a high rate and that a large proportion would return to their preoperative level of performance.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review of the literature was conducted using PubMed and Cochrane Library databases to identify articles reporting return to sport after MPFL reconstruction for recurrent patellar dislocation. Athletes were defined as those reporting a preoperative sport. A random-effects model was used to evaluate return to sport rates, subsequent level, and rate of instability recurrence. Meta-regression was used to compare return to sport rates in patients undergoing MPFL reconstruction without osteotomy compared with those treated with simultaneous tibial tubercle osteotomy or trochleoplasty.

RESULTS

In total, 23 articles met inclusion criteria after full-text review. A total of 930 patients were analyzed, including 786 athletes. Women represented 61.3% of all patients. The overall mean age was 21.1 years (range, 9.5-60.0 years), with a mean follow-up time of 3.0 years (range, 0.8-8.5 years). The return to sport rate was 92.8% (95% CI, 86.4-97.6). Patients returned to or surpassed their preoperative level of activity in 71.3% (95% CI, 63.7-78.4) of cases. An osteotomy was performed on 10.5% of athletes. Return to sport did not differ significantly in patients undergoing MPFL reconstruction without osteotomy versus those receiving additional osteotomy (95.4% vs 86.9%; P = .22). Patients returned to sport at a mean of 6.7 months (range, 3.0-6.4 months) postoperatively. Osteotomy did not affect return time. Complications occurred at an overall rate of 8.8%. The most common complication was recurrence of instability (1.9%; 95% CI, 0.4-4.0). The Kujala score was reported by 13 studies, with pre- and postoperative combined means of 60.3 and 90.0, respectively.

CONCLUSION

MPFL reconstruction is an effective and reliable treatment in the setting of patellofemoral instability. Surgeons can counsel their patients that they can expect a high rate of return to sport after MPFL reconstruction surgery alone or with concomitant osteotomy.

Advanced training enhances readiness to return to sport after anterior cruciate ligament reconstruction

Patients with anterior cruciate ligament reconstruction (ACLR) are often psychologically and physically under-prepared for sports participation. This study compared readiness to return to sport based on completion of advanced training after ACLR. Patients with ACLR who self-selected participation in a 6-week group-format advanced training program (TRAINING) were compared to age- and sex-matched patients who did not participate (NoTRAINING). Each group had 23 participants (14 females). Advanced training consisted of plyometric, strengthening, and agility exercises. Baseline and follow-up testing included psychological measures (Anterior Cruciate Ligament Return to Sport after Injury [ACL-RSI]; Tampa Scale for Kinesiophobia [TSK-11]; Knee Activity Self-Efficacy [KASE]; and fear intensity for the primary fear-evoking task or situation) and a hop test battery. Return to sport criteria were ACL-RSI score ≥70 points and limb symmetry index ≥90% on all hop tests. At follow-up, KASE score was higher in TRAINING than NoTRAINING (92.7 vs. 89.1 points; respectively), but ACL-RSI, TSK-11 and fear intensity scores were not significantly different between groups. Return to sport criteria passing rate was not significantly different between groups at baseline (TRAINING: 13%, NoTRAINING: 30%) or follow-up (TRAINING: 52%, NoTRAINING: 43%); however, the distribution of criteria met at follow-up differed with more patients in TRAINING than NoTRAINING meeting hop test criteria (30% vs. 4%, respectively) and more patients in NoTRAINING than TRAINING failing to meet any criteria (25% vs. 0%, respectively). Advanced training after ACLR facilitated readiness for sport participation by improving confidence and hop performance, but may not have a preferential effect on fear.

Limb preference impacts single-leg forward hop limb symmetry index values following ACL reconstruction

Following anterior cruciate ligament (ACL) reconstruction limb dominance for performing tasks is not considered when making rehabilitation progression decisions. The purpose of this study was to determine if strength and functional outcomes differ between individuals who injured their preferred or nonpreferred jumping limb and to determine if these same outcomes differ between individuals who injured their preferred or nonpreferred limb used to kick a ball. A secondary purpose was to determine the association of quadriceps strength and single-leg forward hop performance with patient self-reported function. Forty individuals with ACL reconstruction (age = 20.0 ± 4.6 years, height = 174.2 ± 12.7 cm, mass = 71.2 ± 12.7 kg, time since surgery = 5.3 ± 0.8 months) were included in the study. Primary outcome measures included, International Knee Documentation Committee Subjective Knee Form (IKDC) scores, quadriceps limb symmetry index (LSI) values, and single-leg forward hop LSI values. Limb preference was defined two ways, kicking a ball and performing a unilateral jump. There were no significant differences between groups based on injury to the preferred limb to kick a ball for any of the outcome variables. Individuals who injured their nonpreferred jumping limb demonstrated significantly (p = 0.05, d = 0.77) lower single-leg forward hop LSI values (81.1% ± 19.5%) compared to individuals who injured their preferred jumping limb (94.1% ± 12.6%), but demonstrated no differences in IKDC scores or quadriceps LSI values. Quadriceps LSI and single-leg forward hop LSI explained 73% of the variance in IKDC scores, but quadriceps LSI had the strongest association (r = 0.790). These findings suggests that limb preference influences single forward hop LSI values and should be considered following ACL reconstruction.

Return to play testing following anterior cruciate reconstruction - A systematic review & meta-analysis

PURPOSE

The purpose of this study is to systematically review the evidence regarding return to sport evaluation following ACL reconstruction and evaluate the relationship between testing and secondary ACL injury.

METHODS

A systematic review of the literature with PubMed, Ovid MEDLINE, Cochrane Reviews, was performed on June, 2020 based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were included if they compared outcomes following passing and failing RTP testing subsequent to ACLR. Clinical outcomes were compared, with all statistical analysis performed using Review Manager Version 5.3. Correlation was calculated with Spearman testing.

RESULTS

Overall, 8 studies with 1224 patients were included in the analysis. Overall, 34.3% (420/1224) patients passed the RTP testing. Those who passed the RTP testing had a statistically significant 47% lower rate of ACL graft re-rupture compared to those who did not pass the RTP testing (p = 0.03). However, there was a slightly higher, albeit not statistically significant, rate of contralateral ACL rupture in those who passed the RTP testing compared to those who did not (p = 0.42). There was a strong positive correlation between a high rate of patients passing the ACL RTP testing in studies and ACL graft rupture rate in those who failed (0.80).

CONCLUSION

Passing RTP testing following ACLR results in a lower rate of ACL graft rupture, but not contralateral ACL injury. Further evaluation and standardization of RTP testing is necessary in order to increase reliability in identifying patients at risk for re-injury after ACLR.

LEVEL OF EVIDENCE

Level of Evidence III.

Temporal disruption of neuromuscular communication and muscle atrophy following noninvasive ACL injury in rats

Many patients with anterior cruciate ligament (ACL) injuries have persistent quadriceps muscle atrophy, even after considerable time in rehabilitation. Understanding the factors that regulate muscle mass, and the time course of atrophic events, is important for identifying therapeutic interventions. With a noninvasive animal model of ACL injury, a longitudinal study was performed to elucidate key parameters underlying quadriceps muscle atrophy. Male Long-Evans rats were euthanized at 6, 12, 24, or 48 h or 1, 2, or 4 wk after ACL injury that was induced via tibial compression overload; controls were not injured. Vastus lateralis muscle size was determined by wet weight and fiber cross-sectional area (CSA). Evidence of disrupted neuromuscular communication was assessed via the expression of neural cell adhesion molecule (NCAM) and genes associated with denervation and neuromuscular junction instability. Abundance of muscle RING-finger protein-1 (MuRF-1), muscle atrophy F-box (MAFbx), and 45 s pre-rRNA along with 20S proteasome activity were determined to investigate mechanisms related to muscle atrophy. Finally, muscle damage-related parameters were assessed by measuring IgG permeability, centronucleation, CD68 mRNA, and satellite cell abundance. When compared with controls, we observed a greater percentage of NCAM-positive fibers at 6 h postinjury, followed by higher MAFbx abundance 48 h postinjury, and higher 20S proteasome activity at 1 wk postinjury. A loss of muscle wet weight, smaller fiber CSA, and the elevated expression of run-related transcription factor 1 (Runx1) were also observed at the 1 wk postinjury timepoint relative to controls. There also were no differences observed in any damage markers. These results indicate that alterations in neuromuscular communication precede the upregulation of atrophic factors that regulate quadriceps muscle mass early after noninvasive ACL injury.NEW & NOTEWORTHY A novel preclinical model of ACL injury was used to establish that acute disruptions in neuromuscular communication precede atrophic events. These data help to establish the time course of muscle atrophy after ACL injury, suggesting that clinical care may benefit from the application of acute neurogenic interventions and early gait reloading strategies.

Postoperative Rehabilitation and Return to Sport Following Multiligament Knee Reconstruction

Multiligament knee injuries (MLKIs) are debilitating injuries that increasingly occur in young athletes. Return to sport (RTS) has historically been considered unlikely due to the severity of these injuries. Reporting in the literature regarding objective outcomes following MLKI, including RTS, is lacking, as are clear protocols for both rehabilitation progressions and RTS testing. RTS following MLKI is a complex process that requires an extended recovery duration compared to other surgery types. Progressions through postoperative rehabilitation and RTS should be thoughtful, gradual, and criterion based. After effective anatomic reconstruction to restore joint stability, objective measures of recovery including range of motion, strength, movement quality, power, and overall conditioning guide decision-making throughout the recovery process. It is important to frame the recovery process of the athlete in the context of the severity of their injury, as it is typically slower and less linear. Improved reporting on objective outcomes will enhance our understanding of recovery expectations within this population by highlighting persistent deficits that may interfere with a full recovery, including RTS.

Meeting movement quantity or quality return to sport criteria is associated with reduced second ACL injury rate

The purposes of this prospective cohort study were (1) to assess if second anterior cruciate ligament (ACL) injury rate 2 years after ACL reconstruction (ACLR) in those who returned to pivoting sport was associated with meeting (a) quantitative return to sport (RTS) criteria, (b) qualitative RTS criteria, and (c) combined quantitative and qualitative RTS criteria, and (2) to determine why athletes did not return to their preinjury (level of) sport. Athletes after ACLR performed RTS tests immediately before RTS: seven movement quantity (strength and hop test battery) and two movement quality (countermovement jump with LESS score and hop-and-hold test) tests. A 2-year postoperative questionnaire asked for RTS, reasons for not returning to the same (level of) sport and second ACL injuries. One hundred and forty-four athletes (82%) completed the questionnaire and 97 of them returned to a pivoting sport. Seven of these athletes had a second ACL injury. Meeting the hop test battery RTS criterion (absolute risk reduction 11%; p = .047) and hop-and-hold test RTS criterion (absolute risk reduction 15%; p = .031) were both significantly associated with a reduced second ACL injury rate. Meeting combined RTS criteria were not significantly associated with second ACL injury rate. Therefore, RTS tests after ACLR should at least comprise a hop test battery or the hop-and-hold test to reduce second ACL injury risk after return to pivoting sport. Also, one-third of all athletes mentioned fear of reinjury as the main reason for not returning to their preinjury (level of) sport. This psychological component should be taken seriously and discussed during rehabilitation.

Rehabilitation and Return to Sport Testing After Anterior Cruciate Ligament Reconstruction: Where Are We in 2022?

Athletes who sustain an anterior cruciate ligament (ACL) injury often opt for an ACL reconstruction (ACLR) with the goal and expectation to return to sports at the preinjury level. The proportion of athletes who successfully return to preinjury-level sport is low and disappointing, whereas the rate of second ACL injury in athletes under the age of 20 has been reported to be as high as 40% after return to sport (RTS). Although in recent years, new insights pertaining to RTS have been published, the lack of validity of RTS criteria after ACLR remain. The purpose of this clinical commentary is to present a critical overview of the current literature on RTS testing after ACLR.

The top 100 most impactful articles on the anterior cruciate ligament: An altmetric analysis of online media

Objectives:

To identify the top 100 most impactful anterior cruciate ligament articles in online media as measured by the Altmetric Attention Score and compare their characteristics to the most-cited anterior cruciate ligament articles in the scientific literature.

Methods:

The Altmetric database was queried to identify all published articles pertaining to the anterior cruciate ligament. The search yielded 9445 articles, which were stratified by highest to lowest Altmetric Attention Score. The top 100 articles were included. Collected data included article type, article topic, journal name, and online mentions in news, blogs, Twitter, Facebook, Wikipedia, and other sources. The geographic origin of each article was also determined based on the institutional affiliation of the first author.

Results:

Altmetric Attention Score of the top 100 anterior cruciate ligament articles ranged from 109 to 2193 (median 172.0, interquartile range 137.5–271.5). Of the 100 articles, 65 were published in three journals: American Journal of Sports Medicine, British Journal of Sports Medicine, and Journal of Orthopaedic & Sports Physical Therapy. The most prevalent article type was original research (60%), followed by systematic review/meta-analysis (18%). The most prevalent article topic was rehabilitation and return to play after anterior cruciate ligament reconstruction (22%), followed by epidemiology/risk factors (16%), injury prevention (14%), and biomechanics of anterior cruciate ligament injuries (14%). Of the top 100 articles, 54% were American, 31% were European, and 15% were published in other countries outside of the United States and Europe.

Conclusion:

This study used Altmetric Attention Score to identify the 100 most engaged anterior cruciate ligament articles in online media. The characteristics of these articles differed substantially from the most-cited anterior cruciate ligament articles in the literature with regard to article type, article topic, geographic origin, and publication journal. These findings suggest that alternative metrics measure distinct components of anterior cruciate ligament article engagement and add an important dimension to understanding the overall impact of published research on the anterior cruciate ligament.

Unique Considerations for the Pediatric Athlete During Rehabilitation and Return to Sport After Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament (ACL) injuries and surgical intervention in the pediatric population have increased in the recent years. Although surgical techniques have advanced, evidence-based rehabilitation guidelines that consider all aspects of the youth athlete are currently lacking. The purpose of this commentary is to review the current evidence on unique considerations for the pediatric and adolescent population during rehabilitation and return to sport after ACL reconstruction (ACLR), with a focus on children under 18 years of age. This review revealed that returning a youth athlete to sport after ACLR requires knowledge and appreciation of various aspects of the growing athlete different from adults. In addition to postoperative precautions that contribute to a slow rehabilitation process, young athletes need additional time for strength gains. Address risk of reinjury and for contralateral injury by using neuromuscular training and rigorous return-to-sport training programs. Consider return to sport after 9 months because the reinjury rate is high in this population. A combination of time and objective measures, both quantitative and qualitative criteria, and psychological readiness should be used to assess readiness to return to sport and decrease risk of future injury. Healthcare providers should be aware of the psychosocial impact of injury on the youth athletes and refer to sport psychology when necessary.

LEVEL OF EVIDENCE

Level V.

Confidence, ability to meet return to sport criteria, and second ACL injury risk associations after ACL-reconstruction

This study tested the hypotheses that participants with high knee-related confidence at the time of return to sport (RTS) after anterior cruciate ligament (ACL) reconstruction (ACLR) would have a greater likelihood of meeting RTS criteria and would have a higher likelihood of second ACL injury. Participants completed RTS testing when cleared to RTS. Success was defined as an IKDC score more than or equal to 90 and all limb symmetry index (LSI) scores more than or equal to 90%. Confidence groups were created based on response to the KOOS Quality of Life subscale. Incidence of second ACL injury was tracked for 24 months after RTS. Associations among confidence, success in meeting RTS criteria, and second ACL injury were evaluated. At RTS, 37.7% were classified with high knee-related confidence, 26.4% met RTS criteria and 22.0% sustained a second ACL injury post-RTS. A higher proportion of confident participants met all RTS criteria (p = 0.001). Confident participants were over two times more likely to suffer a second ACL injury (odds ratio [OR] = 2.40; 95% confidence interval [CI]:1.21-5.20) (p = 0.02) and participants who were both confident and met all RTS criteria were 10 times more likely to suffer a second ACL injury (OR = 9.6; 95% CI:1.1, 84.2) (p = 0.02) than those who passed all RTS criteria but lacked knee-related confidence. Clinical significance: Confident, young athletes at the time of RTS after ACLR are more likely to meet all RTS criteria and more likely to sustain a second ACL injury after RTS. Future work must consider how the inclusion of additional factors into RTS criteria may better identify those at high risk for poor outcome after ACLR.

Isometric dynamometry, dependent on knee angle, is a suitable alternative to isokinetic dynamometry when evaluating quadriceps strength symmetry in patients following anterior cruciate ligament reconstruction

BACKGROUND

Knee extensor strength deficits increase re-injury risk following anterior cruciate ligament reconstruction (ACLR). This study investigated whether isometric strength testing methods are a suitable alternative to isokinetic assessment for identifying knee extensor strength asymmetry.

METHODS

This study recruited 22 patients at 9-12 months after ACLR and 22 healthy controls. The single hop for distance (SHD) and knee extensor strength via isokinetic (60°/s and 120°/s) and isometric (positions of 90°, 60° and 30° of flexion, from full knee extension) methods were assessed. Absolute scores (normalized to body weight) and limb symmetry indices (LSIs) were calculated, with t-tests employed for statistical comparisons.

RESULTS

The SHD LSI was significantly higher (p < 0.01) than both isokinetic speeds and the 30° isometric position. No significant LSI differences (p > 0.01) existed within isokinetic or isometric test conditions. In ACLR patients, only the 60°/s isokinetic condition was significantly lower (p = 0.005) than the 60° isometric condition. When normalized to body weight, the operated limb in ACLR patients was significantly weaker than the non-operated limb during peak isokinetic strength testing at 60°/s (p = 0.001) and 120°/s (p = 0.010), as well as isometric testing at 30° (p = 0.009). Compared with controls, ACLR patients demonstrated significantly lower (p < 0.01) mean LSIs across most measures.

CONCLUSIONS

Assessment of knee extensor strength via isometric methods appears suitable in the absence of isokinetic testing equipment, though consideration of test angle (30° and 90° knee angles better detect asymmetries similar to isokinetic testing) is important.

Anterior Cruciate Ligament Rehabilitation and Return to Sport: How Fast Is Too Fast?

This article summarizes the benefits and limitations of various approaches of anterior cruciate ligament (ACL) rehabilitation, more specifically a conservative or traditional rehabilitation approach versus a more accelerated approach. The conservative model is considered one with a return to sport at 9 months or later with more time-based criteria, and an accelerated approach is defined as one with a goal of return to sport by 6 months. Although there are some similarities between the 2 types of rehabilitation, key differences exist and will be highlighted. Additionally, we discuss a criteria-based return-to-sport model that we favor.

Level of Evidence

V, expert opinion.

Predictors of patient satisfaction after primary hamstring anterior cruciate ligament reconstruction

BACKGROUND

Predictors of patient satisfaction (PS) after anterior cruciate ligament (ACL) reconstruction are not well known. This study investigated predictors of PS and whether PS was associated with pre-injury level of sport participation, patient reported knee function and quality of life after ACL reconstruction.

METHODS

Patients who underwent primary hamstring ACL reconstruction between January 2015 and December 2017 were retrospectively evaluated. An online survey was used to evaluate PS (yes = satisfied, no = unsatisfied), duration of supervised postoperative rehabilitation, timing of return to pre-injury level of sport, pre-injury level of sport participation, patient reported knee function and quality of life. Preoperative, operative and postoperative variables were collected from the medical records.

RESULTS

A total of 183 patients completed the survey at a median of 3.6 (1.5) years after ACL surgery. At final follow-up, 82% of patients were satisfied with the outcome. Preoperative (e.g. age) and operative (e.g. meniscal tear) variables were not predictors of PS (p > 0.05). Duration of supervised postoperative rehabilitation, timing of return to pre-injury level of sport and postoperative ACL injury were predictors of PS (p = 0.018, p = 0.016 and p < 0.001, respectively). Pre-injury level of sport participation was significantly higher in satisfied compared to unsatisfied patients: 44.7% (n = 67) versus 18.2% (n = 6) (p = 0.005). In addition, satisfied patients reported significantly higher patient reported knee function and quality of life compared to unsatisfied patients (p < 0.001).

CONCLUSION

This study provided data on predictors of PS after primary ACL reconstruction. Furthermore, PS was associated with pre-injury level of sport participation, patient reported knee function and quality of life.

The Return-to-Sport Clearance Continuum Is a Novel Approach Toward Return to Sport and Performance for the Professional Athlete

The concept of returning to sport for a professional athlete is still under debate for the professional athlete in today's sports environment. It is critical for the professional athlete to be able to return to sport at a highly competitive level but also to return in a safe and timely measure. With no "gold standard" of sport testing, it is difficult to determine what the right progression or testing regimen should be. The Return to Sport Clearance Continuum does not look at one moment in time, but looks throughout the continuum of healing to determine readiness for sport. The purpose of this article is to explore the concept of RTS being part of an evolving continuum rather than the traditional notion that RTS is a single decision made at a discrete point in time. The principles of progressive but regular testing procedures including qualitative and quantitative movement are presented to help the professional athlete return to sport at their maximal performance level.

LEVEL OF EVIDENCE

V, expert opinion.

Blood Flow Restriction Enhances Rehabilitation and Return to Sport: The Paradox of Proximal Performance

The use of blood flow restriction (BFR) within rehabilitation is rapidly increasing as further research is performed elucidating purported benefits such as improved muscular strength and size, neuromuscular control, decreased pain, and increased bone mineral density. Interestingly, these benefits are not isolated to structures distal to the occlusive stimulus. Proximal gains are of high interest to rehabilitation professionals, especially those working with patients who are limited due to pain or postsurgical precautions. The review to follow will focus on current evidence and ongoing hypotheses regarding physiologic responses to BFR, current clinical applications, proximal responses to BFR training, potential practical applications for rehabilitation and injury prevention, and directions for future research. Interestingly, benefits have been found in musculature proximal to the occlusive stimulus, which may lend promise to a greater variety of patient populations and conditions. Furthermore, an increasing demand for BFR use in the sports world warrants further research for performance research and recovery.

LEVEL OF EVIDENCE

Level V, expert opinion.

The Single Hop for Distance Test: Reviewing the Methodology to Measure Maximum and Repeated Performance

Context: The single hop for distance (SHD) and Limb Symmetry Index are often used to assess readiness for returning to sport postinjury. However, the sensitivity of SHD Limb Symmetry Index for detecting functional abnormalities is questionable due to the methodological inconsistencies in the literature. The common methods use few repetitions; lacking consideration of repeated maximum performance, or the effect of fatigue (or failed attempts) on repeated maximum performance, required for sport. The objectives were to review the SHD for evaluating repeated maximum performance, and the effect of failed attempts on consistency of performance, in a healthy population of sportspersons. Design: A quantitative, nonexperimental, same-subject, repeated-measures design with 15 healthy Cardiff University students. Method: Participants performed the SHD up to 30 times on each limb, with standardized rests. A failed attempt, if the landing was not controlled, was noted but distance not recorded. Participants stopped if 3 consecutive distances decreased, or 30 repetitions were achieved. Results: Average hop distance increased with each repetition. Only the 28th to 30th hops were between the maximum average value and 1 SD below. With failed repetitions included, the maximum average hop was at repetition 21 with more results falling between the maximum and 1 SD below, demonstrating more consistency in repeated performance. The number of failed repetitions had a trend to increase over time; whether subjects overreach in attempt to achieve maximum performance, or whether due to fatigue is unknown. Conclusion: Maximum performance of SHD is not achieved until multiple repetitions have been conducted. Repeated maximum performance does not drop-off until over 21 repetitions have been conducted. Consistency of repeated maximum performance varies depending on whether failed attempts are included in the analysis. Further investigation into the reasons for failed attempts is required to improve clinical decision making for return to sport postinjury.

Machine learning algorithm to predict anterior cruciate ligament revision demonstrates external validity

PURPOSE

External validation of machine learning predictive models is achieved through evaluation of model performance on different groups of patients than were used for algorithm development. This important step is uncommonly performed, inhibiting clinical translation of newly developed models. Machine learning analysis of the Norwegian Knee Ligament Register (NKLR) recently led to the development of a tool capable of estimating the risk of anterior cruciate ligament (ACL) revision ( https://swastvedt.shinyapps.io/calculator_rev/ ). The purpose of this study was to determine the external validity of the NKLR model by assessing algorithm performance when applied to patients from the Danish Knee Ligament Registry (DKLR).

METHODS

The primary outcome measure of the NKLR model was probability of revision ACL reconstruction within 1, 2, and/or 5 years. For external validation, all DKLR patients with complete data for the five variables required for NKLR prediction were included. The five variables included graft choice, femur fixation device, KOOS QOL score at surgery, years from injury to surgery, and age at surgery. Predicted revision probabilities were calculated for all DKLR patients. The model performance was assessed using the same metrics as the NKLR study: concordance and calibration.

RESULTS

In total, 10,922 DKLR patients were included for analysis. Average follow-up time or time-to-revision was 8.4 (± 4.3) years and overall revision rate was 6.9%. Surgical technique trends (i.e., graft choice and fixation devices) and injury characteristics (i.e., concomitant meniscus and cartilage pathology) were dissimilar between registries. The model produced similar concordance when applied to the DKLR population compared to the original NKLR test data (DKLR: 0.68; NKLR: 0.68-0.69). Calibration was poorer for the DKLR population at one and five years post primary surgery but similar to the NKLR at two years.

CONCLUSION

The NKLR machine learning algorithm demonstrated similar performance when applied to patients from the DKLR, suggesting that it is valid for application outside of the initial patient population. This represents the first machine learning model for predicting revision ACL reconstruction that has been externally validated. Clinicians can use this in-clinic calculator to estimate revision risk at a patient specific level when discussing outcome expectations pre-operatively. While encouraging, it should be noted that the performance of the model on patients undergoing ACL reconstruction outside of Scandinavia remains unknown.

LEVEL OF EVIDENCE

III.

Preoperative predictors for a successful return to sport following anterior cruciate ligament reconstruction (ACLR): a protocol for a systematic review and meta-analysis

INTRODUCTION

Return to sport (RTS) following anterior cruciate ligament reconstruction (ACLR) is the primary goal for most patients. However, the decision of when to RTS is difficult for patients and clinicians as it is based on limited available evidence. Over the past decade, a number of predictor variables have been associated with RTS after ACLR. We present a Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols compliant protocol for a systematic review and meta-analysis of preoperative predictors for RTS/preinjury levels of physical activity following ACLR.

METHODS AND ANALYSIS

A literature search will be performed in six electronic databases (CINAHL, AMED, MEDLINE, SPORTDiscus and PsycINFO via EBSCOhost and Web of Science) from inception to December 2020. Prospective, retrospective and cross-sectional study designs will be included. To be included, studies will need to identify at least one preoperative predictor and identify the relationship between the predictor(s) and RTS/preinjury levels of physical activity following ACLR. Blinded assessment with consensus agreement will be applied for inclusion of studies, data extraction, risk of bias assessment using the Quality in Prognostic Studies tool and the Grading of Recommendations Assessment, Development and Evaluation framework. If data allows and studies are considered homogeneous, data will be pooled through a meta-analysis. If heterogenous, a narrative synthesis will be completed. Subgroup and sensitivity analyses will be completed, where appropriate.

ETHICS AND DISSEMINATION

Ethical permission is not required for this study. The results will be published in a peer-reviewed journal and presented at national and international conferences.

PROSPERO REGISTRATION NUMBER

CRD42020222567.

ACL Reconstruction Rehabilitation: Clinical Data, Biologic Healing, and Criterion-Based Milestones to Inform a Return-to-Sport Guideline

CONTEXT

Anterior cruciate ligament (ACL) reconstruction (ACLR) and postoperative rehabilitation continues to be a multidisciplinary focus in both research and clinical environments. Recent research on ACLR warrants a reexamination of clinicians' current rehabilitation practices to optimize the strikingly variable clinical outcomes after ACLR and return to sport. The purpose of the article and updated guidelines is to use contemporary evidence to systematically revisit our practice guidelines and validate our clinical milestones with data from our university-based practice.

EVIDENCE ACQUISITION

Using the PubMed search engine, articles that reported on ACLR rehabilitation and protocols, guidelines, graft type, healing and strain, return to sport, psychological considerations, and secondary injury prevention published from 1979 to 2020 were identified using the search terms ACLR protocols, guidelines, ACLR rehabilitation, ACL graft, ACL open kinetic chain (OKC) exercise and closed kinetic chain (CKC) exercise, ACLR return to sport, ACLR psychological factors, and ACL injury prevention.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 5.

RESULTS

Clinical milestones after ACLR were validated using clinical data collected from 2013 to 2017 at a university-based practice. Variables including knee joint range of motion, effusion, Knee Outcome Survey-Activities of Daily Living Scale, and quadriceps strength index were tracked throughout rehabilitation and analyzed to help inform an updated ACLR rehabilitation guideline.

CONCLUSION

Incorporating the latest research, combined with direct clinical data, provides a current, realistic, and clinically benchmarked strategy for ACLR rehabilitation. Commonly held clinical beliefs regarding rehabilitation after ACL injury must be challenged by the latest research to improve patient outcomes and decrease the risk of reinjury. Key updates to the practice guidelines include the use of frequent and accurate quadriceps strength testing, delayed return-to-sport timeline, immediate use of open kinetic chain exercise, criterion-based progressions for running, sprinting, plyometrics, agility, cutting/pivoting, return to competition, and the inclusion of a secondary prevention program after return to sport.

STRENGTH OF RECOMMENDATION TAXONOMY (SORT)

B.

Early Return to Sports to Continue the Season after Anterior Cruciate Ligament Injury Is Not Recommended for Student Athletes

Objective:

The objectives of this study were to investigate whether student athletes with anterior cruciate ligament (ACL) injuries who returned to sports (RTS) without reconstruction could continue their sporting activities until the end of the season and whether there was an increase in secondary damage associated with knee instability.

Methods:

Altogether, 288 skeletally mature patients aged <25 years with new-onset isolated primary ACL injuries were included. Of these, 20 student athletes continued playing sports without ACL reconstruction to try to finish the season and were classified as the early return to sports (ERS) group; the remaining 268 patients, who immediately quit sports and underwent surgery, were classified as the non-ERS group. Knee symptoms and sporting performance for the rest of the season were assessed for the ERS group. The presence of secondary damage, e.g., meniscus injuries and chondral lesions, associated with instability were compared between the two groups.

Results:

Fourteen ERS-group athletes (70%) indicated that their knees had given way during sporting activities, and seven athletes (35%) were unable to complete the season. In the ERS group, the mean self-estimated performance level after injury was 3.8 ± 2.5 (numeric rating scale 0–10). Despite the RTS period being relatively short, medial meniscus tears (P <0.001) significantly increased in the ERS group, and three patients experienced locking of the medial meniscus and required immediate surgery.

Conclusions:

Although ERS without reconstruction to complete the season may be a reasonable strategy for ACL injury, patients’ self-estimated performance level was low and meniscal and cartilage injury rates significantly increased.

Recovery After ACL Reconstruction in Male Versus Female Adolescents: A Matched, Sex-Based Cohort Analysis of 543 Patients

Background:

Differences in postoperative recovery after anterior cruciate ligament reconstruction (ACLR) between men and women have been demonstrated in the adult population. Sex-based differences have been incompletely investigated in adolescents, which represent the subpopulation most affected by ACL injury.

Purpose/Hypothesis:

The purpose of this study was to compare the 6-month postoperative functional recovery after ACLR between adolescent boys and girls. It was hypothesized that significant differences in postoperative strength, dynamic balance, and functional hop test performance would be seen between the sexes.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included in this study were athletes aged 12 to 19 years with closed or closing growth plates who underwent ACLR with hamstring autograft between May 2014 and May 2018 at a single institution. All athletes had undergone strength and functional testing between 5 and 8 months postoperatively. Exclusion criteria were previous knee surgery (contralateral or ipsilateral knee), concomitant injury/surgery other than meniscal tear/repair, allograft supplementation, and incomplete medical records. The limb symmetry index (LSI) for strength (measured with handheld dynamometer), as well as dynamic Y-balance and functional hop test performance, was compared between groups. To account for differences in physical characteristics between the sexes, 1-way between-group multivariate analysis of covariance was used to analyze the data.

Results:

Overall, 543 patients (211 boys, 332 girls) were included. There was no significant difference in age, body mass index, incidence of concomitant meniscal pathology, use of regional anesthesia, or time to functional testing between cohorts. Female athletes demonstrated a statistically significantly greater deficit in quadriceps strength LSI compared with male athletes (boys, +3.4%; girls, –2.3%; P = .011). Both male and female athletes demonstrated 33% hamstring strength deficits, with no statistically significant sex-based differences in dynamic balance or functional hop testing.

Conclusion:

Female athletes demonstrated greater quadriceps strength deficits than male athletes at 6 months after ACLR with hamstring autograft. Severe hamstring strength deficits persisted in both male and female patients at this time point. The correlation of such deficits to risk of ACL retear warrants continued study in the adolescent population and may support a delay in return to sports, which has been suggested in the more recent literature.

Short-term isokinetic and isometric strength outcomes after anterior cruciate ligament reconstruction in adolescents

OBJECTIVES

To examine differences in knee strength outcomes after ACL reconstruction according to quadriceps tendon (QT) or hamstring tendon (HT) autograft in adolescents.

DESIGN

Retrospective cohort.

METHODS

Surgical and clinical outcome data were collected. Analyses were conducted separately for female and male cohorts and grouped by graft type (HT or QT). A Mann-Whitney U test of independent samples was used to examine group differences according to graft type.

RESULTS

107 females (age = 15.6 ± 1.5 years) and 94 males (age = 15.7 ± 1.5 years) were included. Mean time since surgery ranged from 7.2 to 7.9 months. Those with a QT autograft had decreased normalized isokinetic quadriceps peak torque on the involved limb compared to the HT group (p < 0.01, ES = 0.71-0.89). Normalized isometric hamstring peak torque was decreased for those with HT autograft in the female cohort (p = 0.02, ES = 0.57).

CONCLUSION

Normalized isokinetic quadriceps peak torque was reduced by 18-20% on the involved limb in those with a QT autograft. Normalized isometric hamstring peak torque was decreased by 13% for those with HT autograft in the female cohort. Method of strength testing may be an important consideration to fully appreciate strength deficits after ACL reconstruction according to graft type.

Identifying Clinical and MRI Characteristics Associated with Quality of Life in Patients with Anterior Cruciate Ligament Injury: Prognostic Factors for Long-Term

BACKGROUND

Associated lesions in the diagnostic MRI may be related to worse long-term subjective outcomes. There is a lack of conclusive information about the long-term outcomes of associated injuries in anterior cruciate ligament (ACL) tears. The purpose of this study is to assess the long-term effects of associated injuries in ACL tears measured by means of a quality of life (QOL) assessment.

METHODS

A retrospective cohort study of 225 consecutive patients admitted for physical therapy with ACL injury (42 ± 12 years, 28.2% female) were conducted. All demographic and clinical variables were used to measure a QOL. Univariate and multivariable analyses were completed.

RESULTS

The mean follow-up period was 8.4 ± 2.6 years. In univariate analysis, male gender, and sports as the cause of the ACL lesion were factors significantly associated with improved International Knee Documentation Committee (IKDC) scores at the end of follow-up (all p < 0.002). In multivariable analysis, the occurrence of bone contusion was positively associated with injury (OR = 2.12) and negatively associated with sports injury (OR = 0.44) and medial collateral ligament (MCL) injury (OR = 0.48).

CONCLUSIONS

After ACL injury, male gender and sports injury were associated with better clinical outcomes.

Single-Leg Vertical Hop Test Detects Greater Limb Asymmetries Than Horizontal Hop Tests After Anterior Cruciate Ligament Reconstruction in NCAA Division 1 Collegiate Athletes

BACKGROUND

Knee function deficits may persist after anterior cruciate ligament reconstruction (ACLR). Return to sport (RTS) testing batteries assess recovery after ACLR and can guide RTS progression, but the ideal test components are debatable. The single leg vertical hop for height (SLVH) test using a commercially available jump mat may provide a valuable assessment of knee function.

HYPOTHESIS/PURPOSE

The purpose of this study was to compare the limb symmetry index (LSI) of SLVH to horizontal hop testing in a cohort of National Collegiate Athletic Association (NCAA) Division 1 collegiate athletes after ACLR. The hypothesis was the SLVH would elicit significantly lower LSI than horizontal hop tests.

STUDY DESIGN

Cross-Sectional Study.

METHODS

Eighteen National Collegiate Athletic Association (NCAA) Division 1 collegiate athletes (7 males, 11 females) at 7.33 ± 2.05 months after ACLR were included in this retrospective study. LSI was calculated for single hop for distance (SHD), triple hop for distance (THD), cross-over hop for distance (CHD), timed 6-meter hop (T6H), and SLVH. A repeated measures ANOVA was performed to identify differences in LSI for each test. Spearman's Rho correlation coefficient was calculated to examine the relationship between LSIs for each test.

RESULTS

The LSI for SLVH (84.48% ± 11.41%) was significantly lower than LSI for SHD (95.48 ± 8.02%, p = 0.003), THD (94.40 ± 3.70%, p = 0.002), CHD (95.85 ± 7.00, p = 0.007), and T6H (97.69 ± 6.60%, p = 0.001). The correlation of LSI between SLVH and the horizontal hop tests was weak and non-significant for SHD (rs = 0.166, p = 0.509), CHD (rs = 0.199, p = 0.428), and T6H (rs = 0.211, p = 0.401) and moderate and non-significant for THD (rs = 0.405, p = 0.096).

CONCLUSIONS

Individuals after ACLR had lower LSI on the SLVH than on horizontal hop tests and weak to moderate correlations between the tests suggest SLVH detects performance deficits not identified by the horizontal hop tests.

LEVEL OF EVIDENCE

3.

A Multi-Systems Approach to Human Movement after ACL Reconstruction: The Musculoskeletal System

Several negative adaptations to the musculoskeletal system occur following anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) such as arthrogenic muscle inhibition, decreased lower extremity muscle size, strength, power, as well as alterations to bone and cartilage. These changes have been associated with worse functional outcomes, altered biomechanics, and increased risk for re-injury and post-traumatic osteoarthritis. After ACL injury and subsequent ACLR, examination and evaluation of the musculoskeletal system is paramount to guiding clinical decision making during the rehabilitation and the return to sport process. The lack of access many clinicians have to devices necessary for gold standard assessment of muscle capacities and force profiles is often perceived as a significant barrier to best practices. Fortunately, testing for deficits can be accomplished with methods available to the clinician without access to costly equipment or time-intensive procedures. Interventions to address musculoskeletal system deficits can be implemented with a periodized program. This allows for restoration of physical capacities by adequately developing and emphasizing physical qualities beginning with mobility and movement, and progressing to work capacity and neuromuscular re-education, strength, explosive strength, and elastic or reactive strength. Additional considerations to aid in addressing strength deficits will be discussed such as neuromuscular electrical stimulation, volume and intensity, eccentric training, training to failure, cross-education, and biomechanical considerations. The American Physical Therapy Association adopted a new vision statement in 2013 which supported further development of the profession's identity by promoting the movement system, yet validation of the movement system has remained a challenge. Application of a multi-physiologic systems approach may offer a unique understanding of the musculoskeletal system and its integration with other body systems after ACLR. The purpose of this clinical commentary is to highlight important musculoskeletal system considerations within a multi-physiologic system approach to human movement following ACLR.

LEVEL OF EVIDENCE

5.

A lifespan approach to osteoarthritis prevention

Prevention is an attractive solution for the staggering and increasingly unmanageable burden of osteoarthritis. Despite this, the field of osteoarthritis prevention is relatively immature. To date, most of what is known about preventing osteoarthritis and risk factors for osteoarthritis is relative to the disease (underlying biology and pathophysiology) of osteoarthritis, with few studies considering risk factors for osteoarthritis illness, the force driving the personal, financial and societal burden. In this narrative review we will discuss what is known about osteoarthritis prevention, propose actionable prevention strategies related to obesity and joint injury which have emerged as important modifiable risk factors, identify where evidence is lacking, and give insight into what might be possible in terms of prevention by focussing on a lifespan approach to the illness of osteoarthritis, as opposed to a structural disease of the elderly. By targeting a non-specialist audience including scientists, clinicians, students, industry employees and others that are interested in osteoarthritis but who do not necessarily focus on osteoarthritis, the goal is to generate discourse and motivate inquiry which propel the field of osteoarthritis prevention into the mainstream.

Longitudinal Changes in Ultrasound-Assessed Femoral Cartilage Thickness in Individuals from 4 to 6 Months Following Anterior Cruciate Ligament Reconstruction

OBJECTIVE

Diagnostic ultrasound provides a valid assessment of cartilage health that has been used to observe cross-sectional cartilage thickness differences post-ACLR (anterior cruciate ligament reconstruction), but has not been used longitudinally during early recovery post-ACLR.

DESIGN

The purpose of this study was to assess longitudinal changes in femoral cartilage thickness via ultrasound in individuals at 4 to 6 months post-ACLR and compared to healthy controls. Twenty participants (50% female, age = 21.1 ± 5.7 years) completed testing sessions 4 and 6 months post-ACLR. Thirty healthy controls (57% female, age = 20.8 ± 3.8 years) without knee injury history completed 2 testing sessions (>72 hours apart). Femoral cartilage ultrasound images were captured bilaterally in ACLR participants and in the dominant limb of healthy controls during all sessions. Average cartilage thicknesses in the medial, intercondylar, and lateral femoral regions were determined using a semi-automated processing technique.

RESULTS

When comparing cartilage thickness mean differences or changes over time, individuals post-ACLR did not demonstrate between limb differences (P-range = 0.50-0.92), limb differences compared to healthy controls (P-range = 0.19-0.94), or changes over time (P-range = 0.22-0.72) for any femoral cartilage thickness region. However, participants demonstrated cartilage thickening (45%) or thinning (35%) that exceeded minimal detectable change (MDC) from 4 to 6 months post-ACLR, respectively.

CONCLUSIONS

Using MDC scores may help better identify within-subject femoral cartilage thickness changes longitudinally post-ACLR due to bidirectional cartilage thickness changes.

Quadricep ACL Reconstruction Techniques and Outcomes: an Updated Scoping Review of the Quadricep Tendon

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date summary on the most recent literature examining techniques and outcomes in anterior cruciate ligament (ACL) reconstruction using quadriceps tendon (QT) which will enable surgeons to make well informed evidence-based decisions when choosing a particular graft option and technique in ACL reconstruction.

RECENT FINDINGS

Several RCTs and systematic reviews have been published recently on this topic, and overall, there were no differences found between the QT, HT, and BPTB groups in patient-reported outcomes, stability testing, or graft re-rupture rates. In terms of strength testing, the QT group did have inferior knee extensor strength on isokinetic testing when compared to the HT group, whereas the HT group had inferior knee flexor strength compared to the QT group. No differences were found on strength testing between the QT and BPTB groups. Currently, two large RCTs, the Stability2 and SQuASH trials, are ongoing examining the effectiveness of the QT vs BPTB with or without LET and QT vs HT in the pediatric population which will help shed further light on the effectiveness of the QT as a graft choice in ACL reconstruction. The findings of this scoping review demonstrate that the QT is an excellent graft option in ACL reconstruction both in the primary and revision settings, among adult and pediatric populations. This review provides surgeons with further assurance when selecting QT autograft in ACL reconstruction.