Anterior cruciate ligament strain and tensile forces for weight-bearing and non-weight-bearing exercises: a guide to exercise selection

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

Introduction

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

Case Description

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

Outcomes

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

Conclusion

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

Level of Evidence

Level 5.

Electromyographic analysis of the traditional and spin throwing techniques for goalball games related to ball velocity for selected upper extremity muscles

BACKGROUND

Goalball is a popular sport among visually impaired individuals, offering many physical and social benefits. Evaluating performance in Goalball, particularly understanding factors influencing ball velocity during throwing techniques, is essential for optimizing training programs and enhancing player performance. However, there is limited research on muscle activation patterns during Goalball throwing movements, needing further investigation to address this gap. Therefore, this study aims to examine muscle activity in sub-elite visually impaired Goalball players during different throwing techniques and visual conditions, focusing on its relationship with ball velocity.

METHODS

15 sub-elite Goalball players (2 female, 13 males; mean age of 20.46 ± 2.23 years) participated in the study. Muscle activity was evaluated with the Myo armband, while ball velocity was measured using two cameras and analyzed with MATLAB software. Different visual conditions were simulated using an eye band, and the effects of these conditions on muscle activation and ball velocity were examined.

RESULTS

The flexor muscles were found to be more active during the spin throw techniques with the eyes open (p = 0.011). The extensor muscles were found to be more active in the eyes-closed spin throw techniques compared to the eyes-open position (p = 0.031). Ball velocity was found related to the flexor muscles. Interestingly, no significant differences in ball velocity were observed between different throwing techniques or visual conditions (p > 0.05).

CONCLUSIONS

Ball velocity, one of the performance indicators of the athlete, is primarily related to upper extremity flexor muscle strength rather than visual acuity. It has less visual acuity, but an athlete with more upper-extremity flexor muscle strength will have an advantage in Goalball game. The spin throw technique, which is reported to provide a biomechanical advantage for professional players in the literature, did not provide an advantage in terms of ball velocity for the sub elite players evaluated in our study. This knowledge can inform the development of targeted training programs aimed at improving technique and enhancing ball velocity in Goalball players.

Nurse-Assisted Rehabilitation Protocols Following Anterior Cruciate Ligament Reconstruction

Despite significant advancements in surgical instruments and operation skills, short- and long-term outcomes following anterior cruciate ligament reconstruction (ACLR) remain unsatisfactory, as many patients fail to return to their pre-injury level of sports. Inadequate ACL rehabilitation is the primary cause of poor outcomes. Nurses have become a crucial element in the rehabilitation process. Although there is no consensus regarding the optimal post-operative rehabilitation protocols, restoring muscle strength and neuromuscular control are consistently the primary goals. This literature review presents nurse-assisted rehabilitation protocols aiming at improving muscle strength and neuromuscular control. The review discusses postoperative rehabilitation, including home-based and supervised rehabilitation, open and closed kinetic chain exercises, eccentric and concentric training, blood flow restriction training, and plyometric training. Each training protocol has its benefits and drawbacks, and should be used cautiously in specific stages of rehabilitation. Neuromuscular training, such as neuromuscular electrical stimulation, neuromuscular control exercises, and vibration therapy, is considered crucial in rehabilitation.

Predictive Refined Computational Modeling of ACL Tear Injury Patterns

Anterior cruciate ligament (ACL) ruptures are prevalent knee injuries, with approximately 200,000 ruptures annually, and treatment costs exceed USD two billion in the United States alone. Typically, the initial detection of ACL tears and anterior tibial laxity (ATL) involves manual assessments like the Lachman test, which examines anterior knee laxity. Partial ACL tears can go unnoticed if they minimally affect knee laxity; however, they will progress to a complete ACL tear requiring surgical treatment. In this study, a computational finite element model (FEM) of the knee joint was generated to investigate the effect of partial ACL tears under the Lachman test (GNRB® testing system) boundary conditions. The ACL was modeled as a hyperelastic composite structure with a refined representation of collagen bundles. Five different tear types (I-V), classified by location and size, were modeled to predict the relationship between tear size, location, and anterior tibial translation (ATT). The results demonstrated different levels of ATT that could not be manually detected. Type I tears demonstrated an almost linear increase in ATT, with the growth in tear size ranging from 3.7 mm to 4.2 mm, from 25% to 85%, respectively. Type II partial tears showed a less linear incline in ATT (3.85, 4.1, and 4.75 mm for 25%, 55%, and 85% partial tears, respectively). Types III, IV, and V maintained a nonlinear trend, with ATTs of 3.85 mm, 4.2 mm, and 4.95 mm for Type III, 3.85 mm, 4.25 mm, and 5.1 mm for Type IV, and 3.6 mm, 4.25 mm, and 5.3 mm for Type V, for 25%, 55%, and 85% partial tears, respectively. Therefore, for small tears (25%), knee stability was most affected when the tears were located around the center of the ligament. For moderate tears (55%), the effect on knee stability was the greatest for tears at the proximal half of the ACL. However, severe tears (85%) demonstrated considerable growth in knee instability from the distal to the proximal ends of the tissue, with a substantial increase in knee instability around the insertion sites. The proposed model can enhance the characterization of partial ACL tears, leading to more accurate preliminary diagnoses. It can aid in developing new techniques for repairing partially torn ACLs, potentially preventing more severe injuries.

Plastic and elastic biomechanical properties of anterior cruciate ligament autografts

BACKGROUND

Anterior cruciate ligament (ACL) rupture is a common orthopedic injury, occurring in roughly 68.6 per 100,000 persons annually, with the primary treatment option being ACL reconstruction. However, debate remains about the appropriate graft type for restoring the native biomechanical properties of the knee. Furthermore, plastic graft elongation may promote increased knee laxity and instability without rupture. This study aims to investigate the plastic properties of common ACL-R graft options.

METHODS

Patellar tendon (PT), hamstring tendon (HT), and quadriceps tendon (QT) grafts were harvested from 11 cadaveric knees (6 male and 5 female) with a mean age of 71(range 55-81). All grafts were mechanically tested under uniaxial tension until failure to determine each graft's elastic and plastic biomechanical properties.

RESULTS

Mechanically, the QT graft was the weakest, exhibiting the lowest failure force and the lowest failure stress (QT < HT, p = 0.032). The PT was the stiffest of the grafts, having a significantly higher stiffness (PT > QT, p = 0.0002) and Young's modulus (PT > QT, p = 0.001; PT > HT, p = 0.041). The HT graft had the highest plastic elongation at 4.01 ± 1.32 mm (HT > PT, p = 0.002). The post-yield behavior of the HT tendon shows increased energy storage capabilities with the highest plastic energy storage (HT > QT, p = 0.012) and the highest toughness (HT > QT, p = 0.032).

CONCLUSION

Our study agrees with prior studies indicating that the failure load of all grafts is above the requirements for everyday activities. However, grafts may be susceptible to yielding before failure during daily activities. This may result in the eventual loss of functionality for the neo-ACL, resulting in increased knee laxity and instability.

Rehabilitation care for pain in elderly knee replacement patients

BACKGROUND

Total knee arthroplasty (TKA) is recognized as the most effective surgical intervention for relieving pain and improving joint mobility and deformity in patients with knee osteoarthritis and other synovial diseases. The application of accelerated postoperative rehabilitation (enhanced recovery after surgery) has demonstrated its efficacy in improving patient outcomes, and early postoperative joint function exercise has become a key prognostic factor in knee replacement. The unexpected appearance of limb pain and swelling hindered the patient's tendency for early mobilization, leading in prolonged hospitalization, delayed functional recovery and negative psychological responses.

AIM

To investigate the impact of incorporating programmed pain nursing with collaborative nursing on elderly patients undergoing knee replacement surgery.

METHODS

A retrospective analysis was conducted on a cohort of 116 patients who underwent TKA at our hospital between July 2019 and July 2021. The patients were divided into two groups: A control group (n = 58) receiving programmatic nursing, and an observed group (n = 58) receiving programmed nursing combined with a collaborative nursing model. A pain management team consisting of attending physicians, head nurses, and responsible nurses was established. Outcome measures included visual analogue scale (VAS) scores, activities of daily living (ADL) scale scores, and functional scores.

RESULTS

The ADL scores of patients in both groups exhibited a continuous increase. However, there was no statistically significant difference in the ADL scores between the two groups at 48 h and the 7th d post-surgery (P > 0.05). Upon reexamination at the 3rd mo, the observation group demonstrated higher ADL scores compared to the control group (67.48 ± 14.69 vs 59.40 ± 16.06, P < 0.05). The VAS scores of both groups significantly decreased, with no significant difference observed between the groups at each time point (P > 0.05). The functional status of patients in both groups exhibited a gradual increase prior to intervention and at the 1st, 2nd, and 3rd month following discharge (P < 0.05). There was no statistically significant difference in knee joint function scores between the two groups at the 1st month after discharge (47.52 vs 45.81, P > 0.05). However, the knee joint function scores of patients in the observation group were significantly higher than those in the control group at the 2nd (59.38 vs 53.19, P < 0.05) and 3rd month (71.92 vs 64.34, P < 0.05) following discharge.

CONCLUSION

The utilization of programmed pain nursing in conjunction with collaborative nursing for out-of-hospital care of TKA patients has demonstrated favorable outcomes, encompassing pain reduction, enhanced prognosis, and improved nursing quality for patients.

Tape-Reinforced Graft Suturing and Retensioning of Adjustable-Loop Cortical Buttons Improve Quadriceps Tendon Autograft Biomechanics in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

PURPOSE

To investigate the biomechanical effects of tape-reinforced graft suturing and graft retensioning for all-soft tissue quadriceps tendon (ASTQT) anterior cruciate ligament reconstruction (ACLR) in a full-construct human cadaveric model.

METHODS

Harvested cadaveric ASTQT grafts were assigned to either (1) double-suspensory adjustable-loop cortical button device (ALD) fixation in which both graft ends were fixed with a suspensory fixation device with (n = 5) or without (n = 5) tape-reinforced suturing or (2) single-suspensory distal tendon fixation in which only the patellar end was fixed with an ALD (n = 5) or fixed-loop cortical button device (FLD) (n = 5). All specimens were prepared using a No. 2 whipstitch technique, and tape-reinforced specimens had an integrated braided tape implant. Graft preparation time was recorded for double-suspensory constructs. Samples were tested on an electromechanical testing machine using a previously published protocol simulating rehabilitative kinematics and loading.

RESULTS

Tape-reinforced graft suturing resulted in greater graft load retention after cycling (11.9% difference, P = .021), less total elongation (mean [95% confidence interval (CI)], 5.57 mm [3.50-7.65 mm] vs 32.14 mm [25.38-38.90 mm]; P < .001), greater ultimate failure stiffness (mean [95% CI], 171.9 N/mm [158.8-185.0 N/mm] vs 119.4 N/mm [108.7-130.0 N/mm]; P < .001), and less graft preparation time (36.4% difference, P < .001) when compared with unreinforced specimens. Retensioned ALD constructs had less cyclic elongation compared with FLD constructs (mean total elongation [95% CI], 7.04 mm [5.47-8.61 mm] vs 12.96 mm [8.67-17.26 mm]; P = .004).

CONCLUSIONS

Tape-reinforced graft suturing improves time-zero ASTQT ACLR construct biomechanics in a cadaveric model with 83% less total elongation, 44% greater stiffness, and reduced preparation time compared with a whipstitched graft without tape reinforcement. ALD fixation improves construct mechanics when compared with FLD fixation as evidenced by 46% less total elongation.

CLINICAL RELEVANCE

Tape-reinforced implants and graft retensioning using ALDs improve time-zero ACLR graft construct biomechanics in a time-zero biomechanical model. Clinical studies will be necessary to determine whether these implants improve clinical outcomes including knee laxity and the incidence of graft rupture.

Influence of strength and balance ability on functional performance in the involved and uninvolved sides after anterior cruciate ligament reconstruction

BACKGROUND

The restoration and management of the uninvolved side have been emphasized to prevent a second anterior cruciate ligament (ACL) injury and to ensure that athletes return to sports after ACL reconstruction.

OBJECTIVE

To determine the factors influencing the single leg hop test (SLHT) and single leg vertical jump test (SLVJT) at 1 year postoperatively after ACL reconstruction in both the involved and uninvolved sides.

METHODS

Ninety-four patients who underwent ACL reconstruction were assessed at 1 year postoperatively. Multiple regression models included eight independent variables with two dependent variables (SLHT and SLVJT.), each on the involved and uninvolved side.

RESULTS

On the involved side, the Y balance test (YBT), extensor peak torque per body weight (PT/BW), Biodex balance system anteroposterior index (BBS-API), and sex accounted for 53.9% of the variance in SLHT (P= 0.002), and extensor PT/BW and YBT accounted for 26.3% of the variance in SLVJT (P= 0.027). On the uninvolved side, YBT, sex, age, BBS-API, and flexor PT/BW accounted for 47.0% of the variance in SLHT (P= 0.046), and flexor PT/BW, YBT, and age accounted for 44.9% of the variance in SLVJT (P= 0.002).

CONCLUSION

Knee extensor strength on the involved side and flexor strength on the uninvolved side influence the two functional performance tests. The YBT was an important factor in the two functional performance tests in both sides. Anteroposterior stability was the only factor that influenced the SLHT bilaterally.

Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) subcategories are affected by subjective running ability and medial single-leg hop distance in postreconstruction patients at 6 months

Purpose

This study aimed to investigate the intricate relationship between physical function factors and each subcategory score of the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale among patients following ACL reconstruction.

Methods

Participants comprised 59 patients who had undergone primary ACL reconstruction using hamstring tendon. The ACL-RSI was completed 6 months after reconstruction and five physical functions were measured in patients on the same day. Simple linear regression was performed multiple times to investigate the relationship between ACL-RSI subcategory scores as a dependent variable and each independent variable (knee strength, leg anterior reach distance, single-leg hop [SLH] distances, side bridge endurance, and subjective running ability). Multiple regression analysis was performed using a stepwise method, with factors showing a risk rate <0.05 in simple linear regression analyses as independent variables and the ACL-RSI in each subcategory score as the dependent variable.

Results

Multiple regression analysis showed that subjective running ability affected all subcategories (p ≤ 0.001), and that the limb symmetry index of medial SLH distance affected both the Emotions (p = 0.047) and Confidence (p = 0.009) subcategories. Higher subjective running ability and greater limb symmetry in the medial SLH were thus positively associated with each dimension of psychological readiness.

Conclusions

This study highlights the differential impact of physical function factors on specific subcategories of the ACL-RSI scale, providing clinicians with insights for designing targeted rehabilitation strategies. This original paper suggests the importance of analysing factors related to subcategory scores in addition to total ACL-RSI score, and could contribute to the understanding of determinants for a successful return to sport following ACL reconstruction.

Level of Evidence

Level IV.

Inline dynamometry provides reliable measurements of quadriceps strength in healthy and ACL-reconstructed individuals and is a valid substitute for isometric electromechanical dynamometry following ACL reconstruction

BACKGROUND

Quadriceps strength testing is recommended to guide rehabilitation and mitigate the risk of second injury following anterior cruciate ligament (ACL) reconstruction. Hand-held dynamometry is a practical alternative to electromechanical dynamometry but demonstrates insufficient reliability and criterion validity in healthy and ACL-reconstructed participants respectively. The purpose of this study is to investigate the reliability and concurrent validity of inline dynamometry for measuring quadriceps strength. The hypotheses are that intra-class correlation coefficient (ICC) values will be >0.90 for reliability and concurrent validity.

METHODS

This was a cross sectional study using a within-participant, repeated measures design. Isometric quadriceps testing was performed at 60° knee flexion in 50 healthy and 52 ACL-reconstructed participants. Interrater reliability, intrarater reliability, and concurrent validity of inline dynamometry was investigated through calculation of ICCs, Bland-Altman analysis, linear regression, standard error of measurement (SEM) and minimal detectable change (MDC).

RESULTS

The lower bounds of the 95% confidence intervals were >0.90 for all reliability and validity ICCs in healthy and ACL-reconstructed participants, except for intrarater reliability in healthy participants using absolute scores (ICC = 0.936 [95% CI 0.890-0.963]). In ACL-reconstructed participants, Bland-Altman bias was 0.01 Nm/kg for absolute and average scores, limits of agreement were -11.74% to 12.59% for absolute scores, the SEM was 0.13Nm/kg (95% CI 0.10-0.17) and the MDC was 0.36Nm/kg (95% CI 0.28 - 0.47).

CONCLUSION

Inline dynamometry is a reliable and economical alternative to electromechanical dynamometry for the assessment of quadriceps strength following ACL-reconstruction.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT05109871).

Optimising the Early-Stage Rehabilitation Process Post-ACL Reconstruction

Outcomes following anterior cruciate ligament reconstruction (ACLR) need improving, with poor return-to-sport rates and a high risk of secondary re-injury. There is a need to improve rehabilitation strategies post-ACLR, if we can support enhanced patient outcomes. This paper discusses how to optimise the early-stage rehabilitation process post-ACLR. Early-stage rehabilitation is the vital foundation on which successful rehabilitation post-ACLR can occur. Without high-quality early-stage (and pre-operative) rehabilitation, patients often do not overcome major aspects of dysfunction, which limits knee function and the ability to transition through subsequent stages of rehabilitation optimally. We highlight six main dimensions during the early stage: (1) pain and swelling; (2) knee joint range of motion; (3) arthrogenic muscle inhibition and muscle strength; (4) movement quality/neuromuscular control during activities of daily living (5) psycho-social-cultural and environmental factors and (6) physical fitness preservation. The six do not share equal importance and the extent of time commitment devoted to each will depend on the individual patient. The paper provides recommendations on how to implement these into practice, discussing training planning and programming, and suggests specific screening to monitor work and when the athlete can progress to the next stage (e.g. mid-stage rehabilitation entry criteria).

Asymmetric loading strategies during squats following anterior cruciate ligament reconstruction: A longitudinal investigation with curve analyses throughout and after rehabilitation

Investigations of kinetic asymmetries during bilateral squats following anterior cruciate ligament reconstruction (ACLR) are limited to mainly cross-sectional studies and discrete value data extracted at specific knee angles. We assessed loading asymmetries during squats longitudinally throughout rehabilitation using curve analysis and compared patient-reported outcome measures (PROMs) between those with and without asymmetry. Bodyweight squats were performed by 24 individuals (13 females) post-ACLR on three occasions: (1) Early 2.9 (1.1) months; (2) Mid 8.8 (3.1) months; (3) at Return to Sport (RTS) 13.1 (3.6) months; and 29 asymptomatic controls (22 females) once. Time-normalized between-leg asymmetry curves of sagittal plane hip, knee, and ankle moments and vertical ground reaction forces were compared using functional data analysis methods. Individual asymmetrical loading for ACLR was classified when exceeding the 95% confidence interval of controls during ≥50% of the squat. At Early, ACLR had greater asymmetry than controls for knee (15%-100% eccentric phase; 0%-100% concentric) and ankle flexion moments (56%-65% concentric). At Mid, ACLR had greater asymmetry for knee (41%-72% eccentric) and ankle flexion moments (56%-69% concentric). No between-group differences were found at RTS. From Early to RTS, ACLR reduced asymmetry for hip (21%-46% eccentric), knee (27%-58% concentric), and ankle flexion moments (21%-57% eccentric). At Early, 11/24 underloaded their ACLR knee and 1 overloaded compared with controls. At RTS, 4 underloaded and 6 overloaded. No differences in PROMs were found based on loading asymmetry. Beyond the early phase of rehabilitation from ACLR, individual-level analyses are required to reveal differing loading strategies during bilateral squats.

A non-weight bearing protocol after ACL reconstruction improves static anterior tibial translation in patients with elevated slope and increased weight bearing tibial anterior translation

PURPOSE

Aim of this study is to evaluate the impact of a non-weight bearing (NWB) protocol within 21 post-operative days after anterior cruciate ligament (ACL) reconstruction on static and dynamic anterior tibial translations (SATT and DATT, respectively). The hypothesis is that delayed WB would improve ATT at 9 months follow-up.

METHODS

A series of patients treated with ACL reconstruction was retrospectively reviewed, comparing a group with immediate post-operative weight bearing (WB group) and a group without post-operative weight bearing (NWB group). The NWB protocol was applied to patients with posterior tibial slope (PTS) ≥ 12°, pre-operative SATT ≥ 5 mm, and/or meniscal lesions of root or radial type. SATT, and PTS were measured on 20° flexion monopodal lateral x-rays, while DATT on Telos™ x-rays at pre-operative and 9-months follow-up.

RESULTS

One hundred seventy-nine patients were included (50 NWB group, 129 WB group). The SATT worsened in the WB group with a mean increase of 0.7 mm (SD 3.1 mm), while in the NWB group, the SATT improved with a mean decrease of 1.4 mm (SD 3.1 mm) from the pre-operative to 9 months' follow-up (p < 0.001). The side-to-side Telos™ evaluation showed a significant improvement in DATT within both the groups (p < 0.001), but there was no difference between the two groups (p = 0.99).

CONCLUSION

The post-operative protocol of 21 days without WB led to an improvement in SATT at 9 months without an influence on DATT, and it is recommended for patients with a SATT ≥ 5 mm and/or a PTS ≥ 12° as part of an "à la carte" approach to ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, Retrospective case series.

Enthesis maturation in engineered ligaments is differentially driven by loads that mimic slow growth elongation and rapid cyclic muscle movement

Entheses are complex attachments that translate load between elastic-ligaments and stiff-bone via organizational and compositional gradients. Neither natural healing, repair, nor engineered replacements restore these gradients, contributing to high re-tear rates. Previously, we developed a culture system which guides ligament fibroblasts in high-density collagen gels to develop early postnatal-like entheses, however further maturation is needed. Mechanical cues, including slow growth elongation and cyclic muscle activity, are critical to enthesis development in vivo but these cues have not been widely explored in engineered entheses and their individual contribution to maturation is largely unknown. Our objective here was to investigate how slow stretch, mimicking ACL growth rates, and intermittent cyclic loading, mimicking muscle activity, individually drive enthesis maturation in our system so to shed light on the cues governing enthesis development, while further developing our tissue engineered replacements. Interestingly, we found these loads differentially drive organizational maturation, with slow stretch driving improvements in the interface/enthesis region, and cyclic load improving the ligament region. However, despite differentially affecting organization, both loads produced improvements to interface mechanics and zonal composition. This study provides insight into how mechanical cues differentially affect enthesis development, while producing some of the most organized engineered enthesis to date. STATEMENT OF SIGNIFICANCE: Entheses attach ligaments to bone and are critical to load transfer; however, entheses do not regenerate with repair or replacement, contributing to high re-tear rates. Mechanical cues are critical to enthesis development in vivo but their individual contribution to maturation is largely unknown and they have not been widely explored in engineered replacements. Here, using a novel culture system, we provide new insight into how slow stretch, mimicking ACL growth rates, and intermittent cyclic loading, mimicking muscle activity, differentially affect enthesis maturation in engineered ligament-to-bone tissues, ultimately producing some of the most organized entheses to date. This system is a promising platform to explore cues regulating enthesis formation so to produce functional engineered replacements and better drive regeneration following repair.

The effects of regional quadriceps architecture on angle-specific rapid force expression

Evaluating anatomical contributions to performance can increase understanding of muscle mechanics and guide physical preparation. While the impact of anatomy on muscular performance is well studied, the effects of regional quadriceps architecture on rapid torque or force expression are less clear. Regional (proximal, middle, and distal) quadriceps (vastus lateralis, rectus femoris, and vastus intermedius) thickness (MT), pennation angle (PA), and fascicle length (FL) of 24 males (48 limbs) were assessed via ultrasonography. Participants performed maximal isometric knee extensions at 40°, 70°, and 100° of knee flexion to evaluate rate of force development from 0 to 200 ms (RFD0-200). Measurements were repeated on three occasions with the greatest RFD0-200 and mean muscle architecture measures used for analysis. Linear regression models predicting angle-specific RFD0-200 from regional anatomy provided adjusted correlations (√adjR2) with bootstrapped compatibility limits. Mid-rectus femoris MT (√adjR2 = 0.41-0.51) and proximal vastus lateralis FL (√adjR2 = 0.42-0.48) were the best single predictors of RFD0-200, and the only measures to reach precision with 99% compatibility limits. Small simple correlations were found across all regions and joint angles between RFD0-200 and vastus lateralis MT (√adjR2 = 0.28 ± 0.13; mean ± SD), vastus lateralis FL (√adjR2 = 0.33 ± 0.10), rectus femoris MT (√adjR2 = 0.38 ± 0.10), and lateral vastus intermedius MT (√adjR2 = 0.24 ± 0.10). Between-correlation comparisons are reported within the article. Researchers should measure mid-region rectus femoris MT and vastus lateralis FL to efficiently and robustly evaluate potential anatomical contributions to rapid knee extension force changes, with distal and proximal measurements providing little additional value. However, correlations were generally small to moderate, suggesting that neurological factors may be critical in rapid force expression.

Effects of accelerated rehabilitation exercise on quadriceps femoris and postural stability after anterior versus posterior cruciate ligament reconstruction

This study aimed to investigate the effect of a 12-week accelerated rehabilitation exercise program on isokinetic strength and dynamic balance ability of thighs in 20 adult men who underwent anterior cruciate ligament reconstruction (ACLR) or posterior cruciate ligament reconstruction (PCLR) and to analyze intergroup differences in recovery patterns. In this study, we examined 10 patients who underwent ACLR and 10 who underwent PCLR. These patients participated in an accelerated rehabilitation exercise program 5 times weekly for 12 weeks. The participants' isokinetic strength, muscular endurance, and dynamic balance ability of the femoral muscles were measured before and 12 weeks after reconstruction surgery. Isokinetic knee muscle function showed no significant difference between the ACLR and PCLR groups at 60°/sec. Both the groups demonstrated significant increases in muscle strength between the flexors and extensors. However, a between-group difference was noted in knee muscular endurance at 180°/sec, with ACLR patients showing significant differences between extensors and flexors, unlike PCLR patients. Assessment of the dynamic balance ability revealed that overall knee stability did not significantly differ between groups, and both the ACLR and PCLR groups exhibited improved dynamic balance ability. However, significant differences were found in anteroposterior and left-right stabilities. Patients who underwent ACLR had significantly improved anteroposterior and left-right stability, wherever patients who underwent PCLR showed no significant difference. This accelerated rehabilitation exercise program improved the muscle strength and muscular endurance of patients who underwent ACLR and PCLR, suggesting its potential efficacy in recovering dynamic balance ability, particularly after ACLR.

The effect of trunk and shank position on the hip-to-knee moment ratio in a bilateral squat

OBJECTIVES

The effect of knee position on joint moments during squats has been studied; however, the effect of trunk angle has been less well investigated. This study evaluated the effect of both trunk and knee sagittal plane position on the distribution of moments between the hip and knee extensors during the bilateral squat.

DESIGN

Observational study.

SETTING

Biomechanics laboratory.

PARTICIPANTS

One hundred individuals performed bilateral squats.

MAIN OUTCOME MEASURES

Motion and force data were collected using motion capture and force plates. Trunk and shank angles and hip and knee moments were calculated. A linear regression was used to associate the ratio between the hip and knee moments (hip-to-knee moment ratio) with the sagittal plane trunk and shank angles, while accounting for six squat depths (between 60° and 110° of knee flexion) and side.

RESULTS

Trunk angle and shank angle each contributed to the hip-to-knee moment ratio (P < .001) with trunk accounting for a higher proportion of variance than the other variables. The hip-to-knee moment ratio increased with increasing trunk angle and with decreasing shank angle.

CONCLUSIONS

This large cohort study supports the use of trunk position to instruct squat technique with the goal of modifying hip and knee moments.

Graft-Specific Surgical and Rehabilitation Considerations for Anterior Cruciate Ligament Reconstruction with the Quadriceps Tendon Autograft

Anterior cruciate ligament reconstruction (ACLR) with a bone-patellar tendon-bone (BPTB) or hamstring tendon (HT) autograft has traditionally been the preferred surgical treatment for patients returning to Level 1 sports. More recently, international utilization of the quadriceps tendon (QT) autograft for primary and revision ACLR has increased in popularity. Recent literature suggests that ACLR with the QT may yield less donor site morbidity than the BPTB and better patient-reported outcomes than the HT. Additionally, anatomic and biomechanical studies have highlighted the robust properties of the QT itself, with superior levels of collagen density, length, size, and load-to-failure strength compared to the BPTB. Although previous literature has described rehabilitation considerations for the BPTB and HT autografts, there is less published with respect to the QT. Given the known impact of the various ACLR surgical techniques on postoperative rehabilitation, the purpose of this clinical commentary is to present the procedure-specific surgical and rehabilitation considerations for ACLR with the QT, as well as further highlight the need for procedure-specific rehabilitation strategies after ACLR by comparing the QT to the BPTB and HT autografts.

Level of Evidence

Level 5.

Rehabilitation of anterior knee pain in the pregnant athlete: Considerations and modifications by trimester

BACKGROUND

Anterior knee pain is a common symptom many females experience during pregnancy. There are several musculoskeletal changes that occur in anatomy and physiology throughout the course of pregnancy that impact the lower extremity kinetic chain. Pregnant athletes, recreational through competitive, who attempt to maintain a high activity level through each trimester may be at increased risk for anterior knee pain due to a greater demand for lumbopelvic and hip stabilization.

CLINICAL QUESTION

What are the evidence-driven rehabilitation guidelines and specific modifications needed to treat anterior knee pain in the female athlete during each trimester of pregnancy?

KEY RESULTS

We aim to provide an overview of rehabilitation treatment guidelines for pregnant females with anterior knee pain, presenting specific physiological changes and rationale for modifications, discussed by trimester. We recommend our program be conducted under the supervision of a physical therapist working closely with the athlete's obstetrics and sports medicine team.

CLINICAL APPLICATION

The number of women who are active during pregnancy is increasing. We provide an overview of the guidelines and considerations for treating women with anterior knee pain during a healthy and uneventful pregnancy.

Impact of Occupation on 12-Month Outcomes After Anterior Cruciate Ligament Reconstruction in Male Patients

Background

The impact of a physically demanding occupation on clinical outcomes after anterior cruciate ligament (ACL) reconstruction (ACLR) is largely unknown.

Purpose/Hypothesis

The purpose of this study was to assess the influence of occupation on 12-month outcomes after ACLR in male patients. It was hypothesized that patients undertaking manual work would not only have better functional outcomes in terms of strength and range of motion but also higher rates of joint effusion and greater anterior knee laxity.

Study Design

Cohort study; Level of evidence, 3.

Methods

From an initial cohort of 1829 patients, we identified 372 eligible patients aged 18 to 30 years who underwent primary ACLR between 2014 and 2017. Based on a preoperative self-assessment, 2 groups were established: patients engaged in heavy manual occupations and those engaged in low-impact occupations. Data were collected from a prospective database including effusion, knee range of motion (using side-to-side difference), anterior knee laxity, limb symmetry index for single hop and triple hop, International Knee Documentation Committee (IKDC) subjective score, and complications up to 12 months. Because of the significantly lower rate of female patients undertaking heavy manual occupations compared to low-impact occupations (12.5% and 40.0%, respectively), data analysis was focused on male patients. Outcome variables were assessed for normality, and statistical comparisons were made between the heavy manual and low-impact groups using either an independent-samples t test or the Mann-Whitney U test.

Results

Of 230 male patients, 98 were included in the heavy manual occupation group, and 132 were included in the low-impact occupation group. Patients in the heavy manual occupation group were significantly younger than those in the low-impact occupation group (mean age, 24.1 vs 25.9 years, respectively; P < .005). There was a greater range of active and passive knee flexion in the heavy manual occupation group than in the low-impact occupation group (mean active, 3.38° vs 5.33°, respectively [P = .021]; mean passive, 2.76° vs 5.00°, respectively [P = .005]). There was no difference in effusion, anterior knee laxity, limb symmetry index, IKDC score, return-to-sport rate, or graft rupture rate at 12 months.

Conclusion

At 12 months after primary ACLR, male patients engaged in heavy manual occupations had a greater range of knee flexion, with no difference in the effusion rate or anterior knee laxity, compared with those engaged in low-impact occupations.

My Top Five Concepts for Selecting Lower Extremity Exercises For Cruciate Ligament and Patellofemoral Rehabilitation

This clinical commentary will address five key concepts that can be used by clinicians as criteria for selecting lower extremity weight bearing exercises (WBE) and non-weight bearing exercises (NWBE) employed for cruciate ligament and patellofemoral rehabilitation. The following will be discussed for both cruciate ligament and patellofemoral rehabilitation: 1) Knee loading varies between WBE and NWBE; 2) Knee loading varies with technique variations within WBE and NWBE; 3) Knee loading varies between different WBE; 4) Knee loading varies as a function of knee angle; and 5) Knee loading increases with increased knee anterior translation beyond toes.

Pelvic Rotation Is Associated With Asymmetry in the Knee Extensor Moment During Double-Leg Squatting After Anterior Cruciate Ligament Reconstruction

Asymmetry in knee extensor moment during double-leg squatting was observed after anterior cruciate ligament reconstruction, even after the completion of the rehabilitation program for return to sports. The purpose of this study was to clarify the association between asymmetry in the knee extensor moment and pelvic rotation angle during double-leg squatting after anterior cruciate ligament reconstruction. Twenty-four participants performed double-leg squatting. Kinetics and kinematics during squatting were analyzed using a 3-dimensional motion analysis system with 2 force plates. The limb symmetry index of knee extensor moment was predicted by the pelvic rotation angle (R2 = .376, P = .001). In addition, the pelvic rotation and the limb symmetry index of the vertical ground reaction force independently explained the limb symmetry index of the knee extensor moment (R2 = .635, P < .001, β of pelvic rotation = -0.489, β of vertical ground reaction force = 0.524). Pelvic rotation toward the involved limb was associated with a smaller knee extensor moment in the involved limb than in the uninvolved limb. The assessment of pelvic rotation would be useful for partially predicting asymmetry in the knee extensor moment during double-leg squatting. Minimizing pelvic rotation may improve the asymmetry in the knee extensor moment during double-leg squatting after anterior cruciate ligament reconstruction.

Exercise Selection and Common Injuries in Fitness Centers: A Systematic Integrative Review and Practical Recommendations

Weight resistance training (RT) is an essential component of physical conditioning programs to improve the quality of life and physical fitness in different ages and populations. This integrative review aimed to analyze the scientific evidence on the relationship between exercise selection and the appearance of musculoskeletal injuries in physical fitness centers (PFC). The PubMed or Medline, EMBASE or Science Direct, Google Scholar and PEDro databases were selected to examine the available literature using a Boolean algorithm with search terms. The review process was performed using the five-stage approach for an integrative review and it was reported according to the PRISMA in Exercise, Rehabilitation, Sport Medicine and Sports Science (PERSiST) guidelines. A total of 39 peer-reviewed articles (Price index = 71.7%) met the inclusion criteria and evaluated the link between exercise selection and the incidence of injuries in exercisers who regularly attend PFC. Most injuries occur to the shoulders, elbows, vertebrae of the spine, and knees. Although the injury etiologies are multifactorial, the findings of the reviewed articles include the impacts of overuse, short post-exercise recovery periods, poor conditioning in the exercised body areas, frequent use of heavy loads, improper technique in certain exercises, and the abuse of performance- and image-enhancing drugs. Practical recommendations addressed to clinical exercise physiologists, exercise professionals, and health professionals are given in this paper. The exercise selection in RT programs requires professional supervision and adhering to proper lifting techniques and training habits that consider the anatomical and biomechanical patterns of the musculoskeletal structures, as well as genetic, pedagogical, and methodological aspects directly related to the stimulus-response process to mitigate the occurrence of RT-related injuries in PFC.

Novel press-fit technique of patellar bone plug in anterior cruciate ligament reconstruction is comparable to interference screw fixation

PURPOSE

Conventional press-fit technique for anterior cruciate ligament reconstruction (ACLR) is performed with extraction drilling of the femoral bone tunnel and manual shaping of the patellar bone plug. However, the disadvantages of this technique include variation in bone plug size and, thus, the strength of the press-fit fixation, bone loss with debris distribution within the knee joint, potential heat necrosis, and metal wear debris due to abrasion of the guide wire. To overcome these disadvantages, a novel technique involving punching of the femoral bone tunnel and standardized compression of the bone plug was introduced. In this study, the fixation strength and apparent stiffness were tested and compared to that of the gold-standard interference screw fixation technique in three flexion angle configurations (0°/45°/90°) in a porcine model. We hypothesized that the newly developed standardized press fit fixation would not be inferior to the gold standard method.

METHODS

Sixty skeletally mature porcine knees (30 pairs) were used. Full-thickness central third patellar tendon strips were harvested, including a patellar bone cylinder of 9.5 mm in diameter. The specimens were randomly assigned to 10 pairs per loading angle (0°, 45°, 90°). One side of each pair was prepared with the press-fit technique, and the contra-lateral side was prepared with interference screw fixation. Equivalent numbers of left- and right-sided samples were used for both fixation systems. A three-way multifactor ANOVA was carried out to check for the influence of (a) fixation type, (b) flexion angle, and (c) side of the bone pair.

RESULTS

The primary fixation strength of femoral press-fit graft fixation with punched tunnels and standardized bone plug compression did not differ significantly from that of interference screw fixation (p = 0.51), which had mean loads to failure of 422.4 ± 134.6 N and 445.4 ± 135.8 N, respectively. The flexion angle had a significant influence on the maximal load to failure (p = 0.01). Load values were highest in 45° flexion for both fixations. The anatomical side R/L was not a statistically significant factor (p = 0.79).

CONCLUSION

The primary fixation strength of femoral press-fit graft fixation with punched femoral tunnels and standardized bone plug compression is equivalent to that of interference screw fixation in a porcine model. Therefore, the procedure represents an effective method for ACL reconstruction with patellar or quadriceps tendon autografts including a patellar bone plug.

Five-Strand Hamstring Grafts are Biomechanically Comparable to Four-Strand Grafts and Offer Greater Diameter for Anterior Cruciate Ligament Reconstruction

Purpose

The purpose of this study was to compare the biomechanics of 4-strand and 5-strand hamstring constructs for anterior cruciate ligament grafts.

Methods

Thirty-six human cadaveric hamstring grafts were tested in 3 different conditions: (1) graft femoral fixation complex, (2) graft femoral and tibial fixation (GFTF) complex using a human model, and (3) GFTF complex using a porcine model. Grafts were tested on a tensile testing machine. Four-stranded grafts served as the control group, and 5-stranded grafts served as the experimental group. Cyclic elongation, ultimate load to failure, stiffness, and diameter of the grafts were analyzed.

Results

Average 4-strand graft diameter was 7.96 mm compared to 9.32 mm for the 5-strand graft (P = .00017). Average stiffness of grafts ≥8 mm was 105.04 N/mm compared to 85.05 N/mm for grafts <8 mm (P = .04988). There was a positive correlation between graft diameter and stiffness (13.4 N/mm per every 1 mm increase in diameter, r² value of 13.1%, and F-significance of 0.02778). There were no significant differences in terms of ultimate load to failure, cyclic elongation, or stiffness between the experimental groups.

Conclusion

Five-strand hamstring grafts offer greater diameter and are biomechanically comparable to 4-strand equivalents at time 0. Grafts >8 mm offer significantly greater stiffness compared to grafts sized <8 mm. There is a weak positive correlation between graft diameter and stiffness.

Clinical Relevance

A potential drawback to hamstring grafts is their variability in size. Five-strand hamstring grafts provide increased diameter in comparison to 4-strand equivalents and might be used when quadrupled graft diameter is <8 mm.

Returning Athletes to Sports Following Anterior Cruciate Ligament Tears

PURPOSE OF REVIEW

The purpose of this review is to discuss treatment options, rehabilitation protocols, return-to-play criteria, and expected outcomes after non-operative and operative treatment of anterior cruciate ligament (ACL) tears among an athletic population.

RECENT FINDINGS

Non-operative treatment may be a viable option for some athletes with an ACL tears but can be difficult to predict "copers," and those that resume to sports return at lower performance level and/or less intense activities. Most studies assessing function after ACL reconstruction demonstrate favorable outcomes using patient-reported outcome studies. However, return-to-play and graft re-rupture rates vary substantially based on patient characteristics and level and type of athletic activity. Grafts used to reconstruct ACL produce similar objective outcomes and favorable patient-reported outcomes but have variable re-rupture rates depending on study and differ largely on morbidity associated with graft harvest. Various treatment methods including non-operative and operative techniques have been demonstrated to be efficacious in returning athletes to athletic activity depending on patient age and level of activity. Adherence to fundamental rehabilitation principles and accepted return-to-play guidelines can optimize outcomes and limit re-injury to the injured or contralateral limb.

Cross-sectional study on relationships between physical function and psychological readiness to return to sport after anterior cruciate ligament reconstruction

BACKGROUND

Information about specific factors of physical function that contribute to psychological readiness is needed to plan rehabilitation for a return to sports. The purpose of this study was to identify specific physical functions related to the psychological readiness of patients aiming to return to sports 6 months after reconstruction. We hypothesized that the knee strength is a factor related to the Anterior Cruciate Ligament-Return to Sport after Injury scale (ACL-RSI) cutoff score for a return to sports.

METHODS

This was a cross-sectional study. Fifty-four patients who had undergone primary reconstruction using hamstring tendon participated in this study. Psychological readiness was measured using the ACL-RSI in patients at 6 months after reconstruction. To identify specific physical functions related to the ACL-RSI score, participants were divided into groups with ACL-RSI scores of ≥ 60 or < 60. Non-paired t-tests or the Mann-Whitney test were performed to analyze group differences in objective variables in physical function: (1) knee strength in both legs; (2) leg anterior reach distance on both sides; and (3) single-leg hop (SLH) distances in three directions for both legs.

RESULTS

Significant differences between groups were identified in knee flexion strength (60°/s) for the uninvolved limb, hamstring-to-quadriceps ratio (60°/s) for the uninvolved limb, knee flexion strength (180°/s) for the involved limb, limb symmetry index (LSI) of leg anterior reach distance, the ratio of the distance to the height of the patient and LSI of SLH distances in lateral and medial directions.

CONCLUSION

This study revealed that at 6 months after reconstruction, increased knee flexion strength (ratio of peak torque measured to body mass of the patient), hamstring-to-quadriceps ratio, leg anterior reach distance LSI, and lateral and medial SLH appear important to exceed the ACL-RSI cutoff for a return to sports. The present results may be useful for planning post-operative rehabilitation for long-term return to sports after reconstruction.

Unilateral Versus Bilateral Resistance Exercise in Postoperative Rehabilitation After ACL Reconstruction With Bone-Patellar Tendon-Bone Graft: A Randomized Controlled Trial

Background

Lower limb muscle strength symmetry has been suggested as an essential criterion for the safe return to sports after anterior cruciate ligament (ACL) reconstruction. Limited evidence is available regarding the most effective intervention to achieve symmetry after reconstruction with contralateral bone-patellar tendon-bone (BPTB) graft.

Purpose

To verify whether unilateral isotonic resistance exercise is more effective than bilateral exercise for obtaining postoperative functional and muscular strength symmetry between the donor limb and reconstructed limb for patients who received BPTB graft.

Study Design

Randomized controlled trial; Level of evidence, 1.

Methods

A total of 88 patients were randomly divided into a control group (n = 44) and an intervention group (n = 44). All participants performed an 8-week exercise program starting at the beginning of the fourth postoperative month and were evaluated before and after the program. The control group performed bilateral exercises, and the intervention group performed unilateral exercises for the donor limb only (the limb with the greatest disability). The primary outcome was muscle strength (peak torque and hamstrings to quadriceps [H:Q] ratio), and the secondary outcomes were range of motion (ROM; goniometry), KT-1000 arthrometer side-to-side difference in anteroposterior knee laxity, and objective (single-leg hop test) and subjective (Lysholm score) functionality.

Results

Both groups improved significantly from before to after the exercise program. The improvements were significantly greater in the intervention group regarding peak torque, H:Q ratio, flexion ROM, single-leg hop test, and Lysholm score in the donor limb (P < .001 for all), and the improvements were significantly greater in the control group regarding peak torque and single-leg hop test in the reconstructed limb (P < .001 for both). Comparison between the groups showed significantly increased symmetry regarding peak torque, H:Q ratio, and single-leg hop test in the intervention group compared with the control group (P < .001), with large effect sizes (>0.80) except for the H:Q ratio.

Conclusion

Although postoperative, bilateral, isotonic resistance exercise provided better strength gains to the reconstructed limb, unilateral exercise was more effective in obtaining functional and muscle strength between-limb symmetry in patients who underwent ACL reconstruction with contralateral BPTB graft.

Registration

Brazilian Registry of Clinical Trials (number RBR-22rnjh).

Association between generalized joint laxity and knee joint movement in female university students

[Purpose] This study investigated the association between generalized joint laxity and knee joint movement in female university students. [Participants and Methods] The study included 21 female university students. Generalized joint laxity was measured using the Beighton criteria for joint hypermobility. Acceleration and angular velocities of the tibia during knee extension were measured along three axes using a triaxial accelerometer. Sampling data were expressed as root mean squares. The Mann–Whitney U test was used to determine differences in the acceleration and angular velocities along each axis between the generalized joint laxity and non-generalized joint laxity groups. Spearman’s rank correlations were used to confirm the association between these parameters. [Results] The rotational angular velocity was greater in the generalized joint laxity than in the non-generalized joint laxity group, and we observed a significant correlation between Beighton scores and the X-axis angular velocity. Furthermore, rotational angular velocity was positively correlated with anterior–posterior acceleration and extension angular velocity. [Conclusion] These findings suggest that rotational angular velocity of the tibia during knee extension is associated with generalized joint laxity in female university students.

The Role of Bracing in ACL Injuries: The Current Evidentiary State of Play

Anterior cruciate ligament (ACL) injuries and surgeries are both increasing in incidence. A notable rate of reinjury and failure does occur after ACL surgery. As a result, interventions that may reduce ACL injury or reinjury are needed and are active areas of innovation. Knee bracing as a strategy to either prevent primary ACL injury, reduce reinjury, or failure after ACL surgery is common. The evidence for bracing around ACL injuries is not straightforward. Clinicians therefore need to understand the relevant literature on bracing around ACL injuries to make personalized decisions for individuals who may be at risk for ACL injury. The purpose of this review is to provide an overview on bracing for ACL injuries and summarize the current available clinical evidence for its use in ACL injuries.

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.

Variability of Multiangle Isometric Force-Time Characteristics in Trained Men

ABSTRACT

Oranchuk, DJ, Storey, AG, Nelson, AR, Neville, JG, and Cronin, JB. Variability of multiangle isometric force-time characteristics in trained men. J Strength Cond Res 36(1): 284-288, 2022-Measurements of isometric force, rate of force development (RFD), and impulse are widely reported. However, little is known about the variability and reliability of these measurements at multiple angles, over repeated testing occasions in a homogenous, resistance-trained population. Thus, understanding the intersession variability of multiangle isometric force-time characteristics provides the purpose of this article. Three sessions of isometric knee extensions at 40°, 70°, and 100° of flexion were performed by 26 subjects across 51 limbs. All assessments were repeated on 3 occasions separated by 5-8 days. Variability was qualified by doubling the typical error of measurement (TEM), with thresholds of 0.2-0.6 (small), 0.6-1.2 (moderate), 1.2-2.0 (large), 2.0-4.0 (very large), and >4.0 (extremely large). In addition, variability was deemed large when the intraclass correlation coefficient (ICC) was <0.67 and coefficient of variation (CV) >10%; moderate when ICC >0.67 or CV <10% (but not both); and small when both ICC >0.67 and CV <10%. Small to moderate between-session variability (ICC = 0.68-0.95, CV = 5.2-18.7%, TEM = 0.24-0.49) was associated with isometric peak force, regardless of angle. Moderate to large variability was seen in early-stage (0-50 ms) RFD and impulse (ICC = 0.60-0.80, CV = 22.4-63.1%, TEM = 0.62-0.74). Impulse and RFD at 0-100 ms, 0-200 ms, and 100-200 ms were moderately variable (ICC = 0.71-0.89, CV = 11.8-42.1%, TEM = 0.38-0.60) at all joint angles. Isometric peak force and late-stage isometric RFD and impulse measurements were found to have low intersession variability regardless of joint angle. However, practitioners need to exercise caution when making inferences about early-stage RFD and impulse measures due to moderate-large variability.

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.

Reliability and Repeatability of ACL Quick Check®: A Methodology for on Field Lower Limb Joint Kinematics and Kinetics Assessment in Sport Applications

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic sport injuries. Even though clinical screenings aiming at identifying subjects at risk of injuries are gaining popularity, the use of sophisticated equipment still represents a barrier towards their widespread use. This study aimed to test both reliability and repeatability of a new methodology to assess lower limb joints kinematics and kinetics directly on field with the aid of video cameras and plantar pressure insoles. Ten athletes and one case study (post ACL surgery) were assessed in a gait laboratory, while performing double leg squats, through the simultaneous acquisition of stereophotogrammetry, force plates, commercial video cameras and plantar pressure insoles. Different sources of errors were investigated and both reliability and repeatability analysis performed. Minimum and maximum RMSE values of 0.74% (right knee joint center trajectory) and 64.51%, respectively (ankle dorsi-plantarflexion moment), were detected. Excellent to good correlation was found for the majority of the measures, even though very poor and inverse between-trials correlation was found on a restricted number of trials especially for the ankle dorsi-plantarflexion moment. These findings could be used in combination with already available screening tools in order to provide more repeatable results.

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.

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.

Local variations in mechanical properties of human hamstring tendon autografts for anterior cruciate ligament reconstruction do not translate to a mechanically inferior strand

A ruptured anterior cruciate ligament (ACL) is often reconstructed with a multiple-strand autograft of a semitendinosus tendon alone or combined with a gracilis tendon. Up to 10% of patients experience graft rupture. This potentially results from excessive local tissue strains under physiological loading which could either result in direct mechanical failure of the graft or induce mechanobiological weakening. Since the original location in the hamstring tendon cannot be traced back from an autograft rupture site, this study explored whether clinical outcome could be further improved by avoiding specific locations or regions of human semitendinosus and/or gracilis tendons in ACL grafts due to potential mechanical or biochemical inferiority. Additionally, it examined numerically which clinically relevant graft configurations experience the lowest strains - and therefore the lowest rupture risk - when loaded with equal force. Remnant full-length gracilis tendons from human ACL reconstructions and full-length semitendinosus- and ipsilateral gracilis tendons of human cadaveric specimens were subjected to a stress-relaxation test. Locations at high risk of mechanical failure were identified using particle tracking to calculate local axial strains. As biochemical properties, the water-, collagen-, glycosaminoglycan- and DNA content per tissue region (representing graft strands) were determined. A viscoelastic lumped parameter model per tendon region was calculated. These models were applied in clinically relevant virtual graft configurations, which were exposed to physiological loading. Configurations that provided lower stiffness - i.e., experiencing higher strains under equal force - were assumed to be at higher risk of failure. Suitability of the gracilis tendon proper to replace semitendinosus muscle-tendon junction strands was examined. Deviations in local axial strains from the globally applied strain were of similar magnitude as the applied strain. Locations of maximum strains were uniformly distributed over tendon lengths. Biochemical compositions varied between tissue regions, but no trends were detected. Viscoelastic parameters were not significantly different between regions within a tendon, although semitendinosus tendons were stiffer than gracilis tendons. Virtual grafts with a full-length semitendinosus tendon alone or combined with a gracilis tendon displayed the lowest strains, whereas strains increased when gracilis tendon strands were tested for their suitability to replace semitendinosus muscle-tendon junction strands. Locations experiencing high local axial strains - which could increase risk of rupture - were present, but no specific region within any of the investigated graft configurations was found to be mechanically or biochemically deviant. Consequently, no specific tendon region could be indicated to provide a higher risk of rupture for mechanical or biochemical reasons. The semitendinosus tendon provided superior stiffness to a graft compared to the gracilis tendon. Therefore, based on our results it would be recommended to use the semitendinosus tendon, and use the gracilis tendon in cases where further reinforcement of the graft is needed to attain the desired length and cross-sectional area. All these data support current clinical standards.

The Natural History of Medial Meniscal Tears in the ACL Deficient and ACL Reconstructed Rat Knee

OBJECTIVE

The process of anterior cruciate ligament (ACL) injury-induced meniscal tear formation is not fully understood. Clinical studies have shown that ACL reconstruction (ACLR) reduces the development of secondary meniscal tears, but it is difficult to gain insight into the protective effects of ACLR from clinical studies alone. Using rat ACL transection (ACLT) and ACLR models, we aimed to reveal (1) the formation process of meniscal tears secondary to ACLT and (2) the protective effects of ACLR on secondary meniscal tears.

DESIGN

ACLT surgery alone or with ACLR was performed on the knees of rats. Histomorphological and histopathological changes were examined in the posteromedial region of the meniscus in intact rats and in rats that received ACLT or ACLR up to 12 weeks postsurgery. In addition, anterior-posterior joint laxity was measured using the universal testing machine to evaluate the effects of ACLT and ACLR on joint laxity.

RESULTS

AAnterior-posterior laxity was significantly increased by ACLT compared to the intact knee. This ACLT-induced joint laxity was partially but significantly reduced by ACLR. Meniscal proliferation and hyaline cartilage-like tissue formation were detected in the medial meniscus at 4 weeks post-ACLT. At 12 weeks post-ACLT, hyaline cartilage-like tissue was replaced by ossicles and meniscal tears were observed. These ACLT-induced abnormalities were attenuated by ACLR.

CONCLUSIONS

Our results suggest that ACLT-induced joint laxity induces secondary medial meniscal tears through meniscal proliferation and ossicle formation via endochondral ossification. Joint re-stabilization by ACLR suppresses meniscal proliferation and ossicle formation and consequently prevents secondary meniscal tears.

Effects of Voluntary Quadriceps-Hamstring Cocontraction on Tibiofemoral Force During Isometric Knee Extension and Knee Flexion Exercises With Constant External Resistance

A biomechanical model has been developed to assess the effects of a voluntary effort of quadriceps-hamstring cocontraction on tibiofemoral force during isometric knee flexion and knee extension exercises with constant external resistance. The model establishes the analytic condition in the moment arms and traction angles of the quadriceps and hamstring muscles that determines the direction (anterior/posterior) of the tibiofemoral shear force developed by the cocontraction. This model also establishes the mechanical effect (loading/unloading) on the anterior cruciate ligament (ACL). At about 15° of knee flexion (where the ACL experiences its maximum quadriceps-induced strain) a voluntary quadriceps-hamstring cocontraction effort yields: (1) nearly the same enhancement in hamstring and quadriceps activation, (2) an increase in hamstring force about 1.5 times higher than that of the quadriceps, and (3) posterior (ACL unloading) tibial pull and compressive tibiofemoral force that increase linearly with the level of quadriceps and hamstring activation. The sensitivity of the results to intersubject variability in the posterior slope of the tibial plateau and muscle moment arms has been estimated with the use of anatomic data available in the literature. An anterior (ACL loading) tibial pull is actually developed at 15° of knee flexion by a voluntary effort of quadriceps-hamstring cocontraction as the posterior tibial slope exceeds 14°.

Effects of and Response to Mechanical Loading on the Knee

Mechanical loading to the knee joint results in a differential response based on the local capacity of the tissues (ligament, tendon, meniscus, cartilage, and bone) and how those tissues subsequently adapt to that load at the molecular and cellular level. Participation in cutting, pivoting, and jumping sports predisposes the knee to the risk of injury. In this narrative review, we describe different mechanisms of loading that can result in excessive loads to the knee, leading to ligamentous, musculotendinous, meniscal, and chondral injuries or maladaptations. Following injury (or surgery) to structures around the knee, the primary goal of rehabilitation is to maximize the patient's response to exercise at the current level of function, while minimizing the risk of re-injury to the healing tissue. Clinicians should have a clear understanding of the specific injured tissue(s), and rehabilitation should be driven by knowledge of tissue-healing constraints, knee complex and lower extremity biomechanics, neuromuscular physiology, task-specific activities involving weight-bearing and non-weight-bearing conditions, and training principles. We provide a practical application for prescribing loading progressions of exercises, functional activities, and mobility tasks based on their mechanical load profile to knee-specific structures during the rehabilitation process. Various loading interventions can be used by clinicians to produce physical stress to address body function, physical impairments, activity limitations, and participation restrictions. By modifying the mechanical load elements, clinicians can alter the tissue adaptations, facilitate motor learning, and resolve corresponding physical impairments. Providing different loads that create variable tensile, compressive, and shear deformation on the tissue through mechanotransduction and specificity can promote the appropriate stress adaptations to increase tissue capacity and injury tolerance. Tools for monitoring rehabilitation training loads to the knee are proposed to assess the reactivity of the knee joint to mechanical loading to monitor excessive mechanical loads and facilitate optimal rehabilitation.

Hamstring Graft Prepared With Suture Tape Is Effective in Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis

Purpose

To investigate the graft diameters and mechanical properties of hamstring tendons sutured using different materials and techniques.

Methods

This study used 30 fresh, frozen human cadaveric semitendinosus tendons; the free ends of 10 specimens each were sutured by 2 No. 3 braided polyester sutures with the Krackow technique (BP group), SutureTape with the Krackow technique (ST group), or SutureTape Loop with the locking SpeedWhip technique (SL group). First, the changes in graft diameter from before suturing to after suturing were investigated. Each graft was pre-tensioned to 100 N for 3 cycles and then cyclically loaded to 200 N for 200 cycles. Elongation after cyclic loading and displacement in the 200th cycle were calculated. Finally, each specimen was loaded to failure. The ultimate failure load and stiffness were analyzed. These mechanical properties were statistically analyzed using 1-way analysis of variance. The level of statistical significance was set at P < .05.

Results

In the BP group, the changes in graft diameter were significantly larger than those in the ST and SL groups (P = .001). The elongation values after 200 cycles in the BP and ST groups were 3.1 ± 2.0 mm and 5.9 ± 3.4 mm, respectively. In the SL group, elongation (7.7 ± 3.6 mm) was significantly larger compared with that in the BP group (P = .037). In contrast, displacement in the 200th cycle was significantly smaller in the ST and SL groups compared with the BP group (P = .017). No statistically significant difference was evident for the ultimate failure loads among the 3 groups (P = .543).

Conclusions

The results of this study suggest that SutureTape may be an appropriate option for preparing the hamstring graft in anatomic anterior cruciate ligament (ACL) reconstruction.

Clinical Relevance

This biomechanical study shows the effectiveness of SutureTape in ACL graft preparation. Clinically, SutureTape may be of benefit in single- or double-bundle ACL reconstruction.

Rehabilitation Principles to Consider for Anterior Cruciate Ligament Repair

CONTEXT

Injury to the anterior cruciate ligament (ACL) is among the most common orthopaedic injuries, and reconstruction of a ruptured ACL is a common orthopaedic procedure. In general, surgical intervention is necessary to restore stability to the injured knee, and to prevent meniscal damage. Along with surgery, intense postoperative physical therapy is needed to restore function to the injured extremity. ACL reconstruction (ACLR) has been the standard of care in recent decades, and advances in surgical technology have reintroduced the prospect of augmented primary repair of the native ACL via a variety of methods.

EVIDENCE ACQUISITION

A search of PubMed database of articles and reviews available in English was performed through 2020. The search terms ACLR, anterior cruciate ligament repair, bridge enhanced acl repair, suture anchor repair, dynamic intraligamentary stabilization, internal bracing, suture ligament augmentation, and internal brace ligament augmentation were used.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 5.

RESULTS

No exact consensus exists on effective rehabilitation protocols after ACL repair techniques, as the variation in published protocols seem even greater than the variation in those for ACLR. For some techniques such as internal bracing and dynamic interligamentary stabilization, it is likely permissible for the patients to progress to full weightbearing and discontinue bracing sooner. However, caution should be applied with regard to earlier return to sport than after ACLR as to minimize risk for retear.

CONCLUSION

More research is needed to address how physical therapies must adapt to these innovative repair techniques. Until that is accomplished, we recommend that physical therapists understand the differences among the various ACL surgery techniques discussed here and work with the surgeons to develop a rehabilitation protocol for their mutual patients.

STRENGTH OF RECOMMENDATION TAXONOMY (SORT)

C.

An association between femoral trochlear morphology and non-contact anterior cruciate ligament total rupture: a retrospective MRI study

INTRODUCTION

The present study aims to investigate the association of the femoral trochlear morphology with the risk of ACL injury and whether this can be considered an additional risk factor in this clinical table.

MATERIALS AND METHODS

This is a retrospective case-control study with 93 patients, 41 patients with ACL total rupture (ACL-TR), and 52 patients without ACL injury who underwent knee magnetic resonance imaging (MRI) between January 2013 and January 2016. The femoral trochlear morphology was evaluated at the proximal and distal levels from the axial knee MRI. The morphological features of the trochlea using sulcus angle, sulcus depth, condylar heights, trochlear sulcus height, percentage of condyles and trochlear sulcus height to transepicondylar width, and lateral and medial trochlear inclination were evaluated. The notch width index was measured on the coronal MR images for notch stenos.

RESULTS

ACL-TR group had a significantly higher sulcus angle (p = 0.00-0.001) and lower sulcus depth (p = 0.00-0.002) than the control group at both levels. Femoral trochlea had morphometric differences between genders. NWI was lower in the ACL-TR group than the control group (control 0.273; ACL-TR 0.247), and there was a statistically significant difference (p = 0.00).

CONCLUSION

This study was shown that the difference in morphology between the trochlear sulcus of patients with normal and ACL injuries should be taken into account in order to increase awareness of ACL injuries. We observed that mild trochlear dysplasia may cause intercondylar notch stenosis rather than changing the localization of the patella. Studies are needed regarding the effect of trochlear dysplasia on ACL.

A Criterion Based Rehabilitation Protocol for ACL Repair with Internal Brace Augmentation

The anterior cruciate ligament (ACL) is one of the main stabilizing structures of the knee and its rupture is a common injury in young active adults. ACL reconstruction has been the preferred operative management of an ACL rupture for several decades; however, success rates are variable. Recently, interest in arthroscopic primary repair of the ligament has increased. The repair is augmented with an Internal Brace (IB), which is an ultra-high strength suture tape that bridges the ligament. This technique protects the ligament during the healing and the ligament is encouraged to heal naturally, whilst not requiring any external braces. It acts as a stabiliser to permit early mobilization and optimise rehabilitation. As understanding of rehabilitation has progressed, there has been an increased focus on early weight-bearing and achieving full range of movement. While detailed criterion-based rehabilitation protocols exist for ACL reconstruction, this is not the case for ACL repair. The purpose of this commentary is to present a novel criterion-based rehabilitation protocol following ACL repair surgery augmented with an IB.

LEVEL OF EVIDENCE

V.

Mechanics of cadaveric anterior cruciate ligament reconstructions during simulated jump landing tasks: Lessons learned from a pilot investigation

BACKGROUND

Around half of anterior cruciate ligament (ACL) injuries are treated through reconstruction, but the literature lacks mechanical investigation of reconstructions in a dynamic athletic task and rupture environment. The current objective was to ascertain the feasibility of investigating ACL reconstructions in a rupture environment during simulated landing tasks in a validated mechanical impact simulator.

METHODS

Four cadaveric lower extremities were subjected to simulated landing in a mechanical impact simulator. External joint loads that mimicked magnitudes recorded from an in vivo population were applied to each joint in a stepwise manner. Simulations were repeated until ACL failure was achieved. Repeated measures design was used to test each specimen in the native ACL and hamstrings, quadriceps, and patellar tendon reconstructed states.

FINDINGS

ACL injuries were generated in 100% of specimens. Graft substance damage occurred in 58% of ACLRs, and in 75% of bone tendon bone grafts. Bone tendon bone and quadriceps grafts survived greater simulated loading than hamstrings grafts, but smaller simulated loading than the native ACL. Median peak strain prior to failure was 20.3% (11.6, 24.5) for the native ACL and 17.4% (9.5, 23.3) across all graft types.

INTERPRETATION

The simulator was a viable construct for mechanical examination of ACLR grafts in rupture environments. Post-surgery, ACL reconstruction complexes are weaker than the native ACL when subjected to equivalent loading. Bone tendon bone grafts most closely resembled the native ligament and provided the most consistently relevant rupture results. This model advocated reconstruction graft capacity to sustain forces generated from immediate gait and weightbearing during rehabilitation from an ACL injury.

Recommendations for Movement Re-training After ACL Reconstruction

It is important to optimise the functional recovery process to enhance patient outcomes after major injury such as anterior cruciate ligament reconstruction (ACLR). Restoring movement quality during sporting-type movements is important prior to return-to-sport (RTS) after ACLR. Alterations in movement quality during an array of functional tasks are common amongst ACLR patients at or near the time of RTS and are associated with worse outcomes after ACLR. The inability to correct movement issues prior to RTS is likely due to the use of incomplete programmes or a lack of volume and intensity of movement re-training programmes. Although most clinicians and researchers understand that re-training movement after ACLR is important (e.g., the 'why'), there is often a disconnect with understanding the 'how' and 'what' of movement re-training post ACLR. The aim of this paper was to discuss factors relevant to movement dysfunction and re-training after ACLR and provide recommendations for clinicians to restore movement quality of patients after ACLR, prior to RTS. The paper recommends: (i) considering the factors which influence the expression of movement quality, which revolve around individual (e.g., neuromuscular, biomechanical, sensorimotor and neurocognitive factors), task-specific and environmental constraints; (ii) incorporating a three-staged movement re-training approach aligned to the ACLR functional recovery process: (1) addressing the neuromuscular and biomechanical and sensorimotor control factors which affect movement quality and motor learning, (2) including a progressive movement re-training approach to re-learn an array of functional tasks optimising coordination and motor learning (3) performing the final aspect of rehabilitation and movement training on the field, in realistic environments progressively simulating the sporting movement demands and environmental constraints; and (iii) effectively designing the movement programme for optimal load management, employing effective coach and feedback techniques and utilising qualitative movement analysis for transition between exercises, stages and for RTS.