Athletes with an ACL reconstruction show a different neuromuscular response to environmental challenges compared to uninjured athletes

BackgroundEvidence suggests that neuromuscular alterations in patients with an anterior cruciate ligament reconstruction (ACLR) are rooted in neurocognitive and proprioceptive deficits. The aim of this study was to assess neuromuscular control of athletes with ACLR under increased cognitive and environmental challenges.Research questionDo athletes with ACLR show a different neuromuscular response to cognitive and environmental challenges relative to controls?MethodsCross-sectional study. Twenty athletes who had an ACLR (age: 23.7 ± 4.3 years, 14 males, time post-surgery: 258.6 ± 54 days) and twenty uninjured controls (age: 21.4 ± 1.5 years, 14 males) performed a stepping down-task in four environmental conditions: no additional challenges, while performing a cognitive dual-task, while undergoing an unpredictable support surface perturbation, and with the cognitive dual-task and unpredictable perturbation combined. Muscle activations of the vastus medialis (VM), vastus lateralis, hamstrings medialis (HM), hamstrings lateralis (HL), gastrocnemius medialis, gastrocnemius lateralis (GL) and gluteus medius were recorded with surface EMG. A three-way ANOVA with main effects for group, dual-task and perturbation was used to compare muscle activations.ResultsAthletes with ACLR show larger HM (ES = 0.45) and HL activation (ES = 1.32) and lower VM activation (ES = 0.72), compared to controls.Athletes with ACLR show a significantly smaller increase in VM (ES = 0.69), VL (ES = 0.53) and GL activation (ES = 0.52) between perturbed and unperturbed tasks compared to controls. Furthermore, under cognitive loading a significantly larger decrease in HM activation (ES = 0.40) and (medial) co-contraction (ES = 0.75) was found in athletes with ACLR compared to controls.SignificanceAthletes with ACLR show an altered neuromuscular response which might represent an arthrogenic muscle response. They show less additional adaptation to perturbed tasks compared to controls, potentially as result of altered proprioceptive input. Furthermore a larger influence of increased cognitive loading on the neuromuscular control was found in athletes with ACLR, indicating that also neurocognitive limitations may contribute to altered neuromuscular control.     

Knee performance and self-efficacy trajectory curves after ACL reconstruction: A longitudinal study

ObjectivesTo examine knee flexion range-of-motion, quadriceps strength, and knee self-efficacy trajectory curves over 6 months after anterior cruciate ligament reconstruction (ACLR), stratified by patients’ Month-6 sports activity level.DesignProspective longitudinal study.SettingHospital outpatient physiotherapy department.Participants595 individuals after unilateral ACLR (mean age, 27 years).Main outcome measuresAt 2-, 3-, and 6-months post-surgery, knee flexion range-of-motion, quadriceps strength, and self-efficacy were quantified. Flexion range-of-motion was additionally measured at 2- and 4-weeks post-surgery. Sports activity levels were assessed using the Tegner Activity Score at 6-months post ACLR.ResultsThe various measures improved nonlinearly over time, with substantial improvements observed in the first 2–4 months post-surgery. In multivariable generalized least squares models, greater knee flexion range-of-motion, quadriceps strength, and self-efficacy over time were significantly associated with higher Month-6 Tegner levels (all P values < 0.01). Additionally, receiving a bone-patellar-tendon-bone graft or meniscal repair was associated with lower quadriceps strength trajectories (P-values<0.001) while female sex was associated with lower knee self-efficacy trajectories (P = 0.02).ConclusionsGreater knee flexion range-of-motion, quadriceps strength, and self-efficacy were associated with higher Month-6 Tegner levels. The derived trajectory curves may be useful for effective management decision making and adequate results interpretation during the rehabilitation process.     

Changes in landing mechanics using augmented feedback: 4-Week training and retention study

ContextNon-contact ACL injuries are common in female athletes during landing tasks. Post-trial performance-based feedback may be an effective method to reduce landing forces and knee valgus during landing. Information regarding the retention of these changes based on such training is generally lacking for weekly and monthly retention.ObjectiveTo determine the effectiveness of post-trial feedback training to promote and retain changes in vertical ground reaction force (vGRF) and knee to ankle (K:A) ratio during a dual task drop landing in female collegiate athletes.DesignRepeated measures;SettingUniversity campus.Participants22 female collegiate athletes.Materials and methodsDual task drop landings were performed over 4 successive weeks with immediate post trial feedback on peak vGRF, symmetry, and K:A ratio. K:A ratio was a surrogate measure for knee valgus in drop landing.ResultsSignificant decreases in vGRF and increases in K:A ratio were found within training sessions (p = .000). Both variables were retained each week over the 4 weeks.ConclusionUsing a custom portable clinical feedback system may be an effective tool in reducing peak vGRFs and knee abduction angles during a drop landing over a 4-week period in female collegiate athletes.     

Intensive supervised rehabilitation versus less supervised rehabilitation following anterior cruciate ligament reconstruction? A systematic review and meta-analysis

ObjectivesTo investigate whether intensive supervised rehabilitation following ACL reconstruction leads to superior self-reported function and sports participation compared to less supervised rehabilitation.DesignSystematic review and meta-analysis.MethodsWe included randomised controlled trials (RCTs) comparing supervised rehabilitation to rehabilitation with a similar protocol that used less supervised sessions for athletes following ACL reconstruction. Two reviewers independently screened studies and extracted data. The Physiotherapy Evidence Database (PEDro) scale was used to evaluate methodological quality and GRADE to evaluate overall quality of evidence. Self-reported function and sports participation were the primary outcomes. Data were pooled using random effects meta-analyses.ResultsOur search retrieved 4075 articles. Seven articles reporting on six RCTs were included (n = 353). Very-low to low-certainty evidence suggests intensive supervised rehabilitation is not superior to less supervised rehabilitation following ACL reconstruction for improving self-reported function, sports participation, knee flexor and extensor strength, range of motion, sagittal plane knee laxity, single leg hop performance, or quality of life.ConclusionBased on uncertain evidence, intensive supervised rehabilitation is not superior to less supervised rehabilitation for athletes following ACL reconstruction. Although high-quality RCTs are needed to provide more certain evidence, clinicians should engage athletes in shared decision making to ensure athletes’ rehabilitation decisions align with current evidence on supervised rehabilitation as well as their preferences and values.     

Patient expectations and perceived social support related to return to sport after anterior cruciate ligament reconstruction in adolescent athletes

ObjectiveExamine the relationship between pre-operative competitive status and return to sport expectations post-operatively among adolescents undergoing ACL reconstruction. Assess the association between perceived levels of social support and doubts in returning to sport after ACL reconstruction.DesignCross-sectional.SettingOutpatient sports medicine clinic at a single institution.Participants12–18 years old with an ACL tear who were planning to undergo ACL reconstruction.Main outcome measuresPsychovitality questionnaire responses and Multidimensional Scale of Perceived Social Support (MSPSS) questionnaire scores.Results86% of participants expected to return to sports in six months or less after surgery; there was no significant difference in expected time to return to sport between competitive vs. recreational athletes. Competitive athletes were less likely to be content returning to a lower activity level after surgery compared to recreational athletes. There were no significant differences in MSPSS scores between those who did and did not report doubts in their ability to return to their previous sports.ConclusionMost of our adolescent athlete population expected to return to sport after ACL reconstruction within six months of surgery. Those with and without doubts in their ability to return to sports did not significantly differ in levels of perceived social support.     

Does the anterolateral ligament protect the anterior cruciate ligament in the most common injury mechanisms? A human knee model study

BackgroundAnterior cruciate ligament (ACL) reconstruction still has a risk of re-rupture and persisting rotational instability. Thus, extra-articular structures such as the anterolateral ligament (ALL) are increasingly treated. The ALL however prevents the internal rotation of the tibia and it must be doubted that the ALL protects the ACL in other common injury mechanisms which primarily include tibial external rotation. In this study we aimed to evaluate which extra-articular structures support the ACL in excessive tibial internal and external rotation using a knee finite element (FE) model.MethodsInternal and external rotations of the tibia were applied to an FE model with anatomical ACL, posterior cruciate ligament (PCL), lateral collateral ligament (LCL), medial collateral ligament (MCL) and intact medial and lateral meniscus. Three additional anatomic structures (anterolateral ligament, popliteal tendon and posterior oblique ligament) were added to the FE model separately and then all together. The force histories within all structures were measured and determined for each case.ResultsThe ACL was the most loaded ligament both in tibial internal and external rotation. The ALL was the main stabilizer of the tibial internal rotation (46%) and prevented the tibial external rotation by only 3%. High forces were only observed in the LCL with tibial external rotation. The ALL reduced the load on the ACL in tibial internal rotation by 21%, in tibial external rotation only by 2%. The POL reduced the load on the ACL by 8%, the PLT by 6% in tibial internal rotation. In tibial external rotation the POL and PLT did not reduce the load on the ACL by more than 1%.ConclusionThe ALL protects the ACL in injury mechanisms with tibial internal rotation but not in mechanisms with tibial external rotation. In injury mechanisms with tibial external rotation other structures that support the ACL need to be considered.     

Delaying ACL reconstruction beyond 6 months from injury impacts likelihood for clinically significant outcome improvement

BackgroundThe effect of surgical latency on outcomes of anterior cruciate ligament reconstruction (ACLR) is a topic that is heavily debated. Some studies report increased benefit when time from injury to surgery is decreased while other studies report no benefit. The purpose of our analysis was to compare achievement of clinically significant outcomes (CSOs) in patients with greater than six months of time from injury to ACLR to those with less than or equal to six months of time to surgery.MethodsPatients undergoing primary ACLR between January 2017 and January 2018 with minimum one year follow-up were included. International Knee Documentation Committee (IKDC) score and Knee Injury and Osteoarthritis Outcomes Score (KOOS) were collected. Multivariate logistic regression was performed for outcome achievement and risk of revision ACLR and Weibull parametric survival analysis was performed for relative time to outcome achievement. The level of significance was set at α = 0.05.Results379 patients were included of which, 140 patients sustained ACL injury greater than six months prior to surgery. This group of patients experienced reduced likelihood to achieve patient-acceptable symptomatic state (PASS) on the IKDC (p = 0.03), KOOS Pain (p = 0.01) and a greater likelihood to undergo revision ACLR (p = 0.001). There was no impact of surgical timing on minimal clinically important difference (MCID).ConclusionPatients with greater than 6 months from injury to ACLR reported reduced likelihood to achieve CSOs, delayed achievement of CSOs, and increased rates of revision surgery.     

Association between ankle angle at initial contact and biomechanical ACL injury risk factors in male during self-selected single-leg landing

BackgroundIncreasing the ankle plantar-flexion angle at initial contact (IC) during landing reduces the impact features associated with landing, such as the vertical ground reaction force and loading rate, potentially affecting the risk of anterior cruciate ligament (ACL) injury. However, the relationships between the ankle plantar-flexion angle at IC and the previously identified biomechanical factors related to noncontact ACL injury have not been studied.Research questionThus, the purpose of this study was to determine whether significant relationships exist between the ankle plantar-flexion angle at IC and the biomechanical factors related to noncontact ACL injury.MethodsThe peak anterior tibial shear force, peak external knee valgus moment, peak knee valgus angle, and combined peak external knee valgus plus tibial internal rotation moments were measured in 26 individuals while performing self-selected, single-leg landing. Pearson correlation analyses were performed to assess the relationships between the ankle plantar-flexion angle at IC and the biomechanical factors mentioned above.ResultsThe greater ankle plantar-flexion angle at IC was related to smaller the peak knee valgus moment (r = −0.5, p = 0.009) and the combined peak knee valgus plus internal rotation moments (r = −0.58, p = 0.001).SignificanceThese results suggest that large ankle plantar-flexion angle at IC might be associated with lesser loading of the knee frontal plane and altering the self-selective ankle angle may result in biomechanical changes associated with ACL injury risk.     

In vitro and in vivo evaluation of heparin mediated growth factor release from tissue‐engineered constructs for anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) rupture is a common injury often necessitating surgical treatment with graft reconstruction. Due to limitations associated with current graft options, there is interest in a tissue‐engineered substitute for use in ACL regeneration. While they represent an important step in translation to clinical practice, relatively few in vivo studies have been performed to evaluate tissue‐engineered ACL grafts. In the present study, we immobilized heparin onto electrospun polycaprolactone scaffolds as a means of incorporating basic fibroblast growth factor (bFGF) onto the scaffold. In vitro, we demonstrated that human foreskin fibroblasts (HFFs) cultured on bFGF‐coated scaffolds had significantly greater cell proliferation. In vivo, we implanted electrospun polycaprolactone grafts with and without bFGF into athymic rat knees. We analyzed the regenerated ACL using histological methods up to 16 weeks post‐implantation. Hematoxylin and eosin staining demonstrated infiltration of the grafts with cells, and picrosirius red staining demonstrated aligned collagen fibers. At 16 weeks postop, mechanical testing of the grafts demonstrated that the grafts had approximately 30% the maximum load to failure of the native ACL. However, there were no significant differences observed between the graft groups with or without heparin‐immobilized bFGF. While this study demonstrates the potential of a regenerative medicine approach to treatment of ACL rupture, it also demonstrates that in vitro results do not always predict what will occur in vivo. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:229–236, 2015.