Patient function in serial assessments throughout the post-ACL reconstruction progression

ObjectiveTo assess the changes in patient strength and function from 4- to 6-month assessments following ACLR, determine relationships between changes in strength to changes in subjective function, and identify factors that predict patients that fail to increase in strength.DesignProspective, Cohort Study.SettingControlled Laboratory.ParticipantsForty-seven patients(27 female, 24.3 ± 11.1 years) completed a battery of performance assessments at approximately 4- and 6-months following primary ACLR (4.03 ±0 .49 and 6.46 ±0 .68 months).Main outcome measuresSubjective scores and isokinetic knee flexor and extensor strength were compared across visits. Patients were categorized per their ability to increase in strength beyond a previously defined threshold(0.22 Nm/kg). Binary logistic regression models were used to determine predictors of patients that failed to meet strength changes.ResultsPatients demonstrated improvements in patient-reported outcomes and strength measures between visits(P’s < 0.05). Higher age (B = −0.073, P = .039), lower pre-injury activity levels (B = 0.61, P = .022), and higher limb symmetry indexes (B = −0.044, P = .05) at 4-months were predictors of patients that did not achieve improvements in quadriceps strength between assessments.ConclusionsFrom 4- to 6-months post-ACLR, increases in subjective function, strength and symmetry were observed. High quadriceps symmetry at interim assessments without consideration of the magnitude of strength values could overestimate recovery of quadriceps function.     

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.     

Quadriceps strength symmetry predicts vertical ground reaction force symmetry during running in patients who have undergone ACL reconstruction

ObjectiveTo determine whether quadriceps strength symmetry can predict peak vertical ground reaction force (vGRF) running force symmetry in patients who have undergone ACL reconstruction (ACLR). We also sought to determine a cutoff for quadriceps strength symmetry to identify patients at risk for vGRF running asymmetry.DesignRetrospective cross-sectional.SettingClinical facility.MethodsBilateral quadriceps strength and vGRF data during running were obtained from 79 patients 26–30 weeks post ACLR. Linear regression was used to determine if quadriceps strength symmetry predicted peak vGRF running force symmetry. Classification and regression tree (CART) analysis was used to determine the cutoff value for quadriceps strength symmetry to identify patients at risk for vGRF running asymmetry.ResultsIncreased quadriceps strength symmetry predicted increased vGRF running symmetry (R² = 0.20). CART analysis revealed that patients with quadriceps strength symmetry less than or equal to 88% were at highest risk for vGRF running asymmetry (R² = 26%).ConclusionGreater quadriceps strength symmetry is predictive of greater vGRF running force symmetry in patients who have undergone ACLR. This finding highlights the need for clinicians to consider the degree of quadriceps strength symmetry before initiating a return to running program.     

Impact of prior anterior cruciate ligament,hamstring or groin injury on lower limb strength and jump kinetics in elite female footballers

ObjectiveTo compare lower limb strength and countermovement jump (CMJ) kinetics between elite female footballers with and without a history of anterior cruciate ligament reconstruction (ACLR), hamstring strain, or hip/groin injury.DesignCross-sectional.SettingField-based.Participants369 elite female Australian football, soccer and rugby league players aged 15–35.Main outcome measuresIsometric hip adductor and abductor strength, eccentric knee flexor strength, and CMJ vertical ground reaction forces, including between-leg asymmetry. Players reported their lifetime history of ACLR, and whether they had sustained a hamstring strain, or hip/groin injury in the previous 12-months.ResultsPlayers with a unilateral history of ACLR (n = 24) had significant between-leg asymmetry in eccentric knee flexor strength (mean = −6.3%, 95%CI = −8.7 to −3.9%, P < .001), isometric hip abductor strength (mean = −2.5%, 95%CI = −4.3 to −0.7%, P = .008), and CMJ peak landing force (mean = −5.5%, 95%CI = −10.9 to −0.1%, P = .046). Together, between-leg asymmetry in eccentric knee flexor strength, isometric hip abductor strength, and CMJ peak landing force distinguished between players with and without prior ACLR with 93% accuracy.ConclusionElite female footballers with a history of ACLR, but not hamstring or hip/groin injury, exhibit persistent between-leg asymmetries in lower limb strength and jump kinetics following a return to sport.     

Psychological readiness at 9 months after anterior cruciate ligament reconstruction –which factors affect?

ObjectiveTo investigate the association of psychological readiness at 9 months after anterior cruciate ligament reconstruction (ACLR) with knee strength and range-of-motion (ROM) at 3 and 9 months postoperatively.DesignRetrospective cohort study.SettingPrivate orthopedic hospital.ParticipantsSeventy-eight patients after ACLR.Main outcomes measuresThe participants completed the anterior cruciate ligament-return to sport after injury (ACL-RSI) scale as an assessment of psychological readiness at 9 months after ACLR. Isometric and isokinetic quadriceps and hamstring strength were measured by a dynamometer at 3 and 9 months postoperatively. Knee extension and flexion ROM were measured in 5° increments with a standard goniometer at 3 and 9 months postoperatively.ResultsUnivariate regression analysis showed that age, limb symmetry index (LSI) of quadriceps strength at 3 and 9 months, and knee extension ROM deficit (>5°) at 3 and 9 months were associated with ACL-RSI scores at 9 months (P < 0.05). Age and LSI of quadriceps strength at 3 months remained significant predictors of ACL-RSI scores at 9 months in multiple regression analysis (R² = 0.20, P < 0.001).ConclusionsEarly improvements in quadriceps strength after ACLR may have a positive impact on psychological readiness at 9 months postoperatively.     

The psychological readiness to return to sports of patients with anterior cruciate ligament reconstruction preoperatively and 6 months postoperatively

ObjectiveTo determine the association of psychological readiness to return to sports preoperative and 6 months post-reconstruction in athletes with anterior cruciate ligament (ACL) injury.DesignRetrospective cohort study.SettingClinical center of sports medicine.ParticipantsFifty athletes, aged 16–45 years, were included in this study. Participants had a modified Tegner activity scale score ≥5 before ACL injury.Main outcome measuresParticipants were divided into High and Low groups based on ACL-return to sport after injury scale (ACL-RSI) scores 6 months post-ACL reconstruction (ACLR) (cutoff: 56 points).ResultsThe Low group had lower ACL-RSI scores than the High group preoperatively (P < 0.001) and 6 months post-ACLR (P < 0.001). The High group had a significantly greater amount of change in ACL-RSI scores preoperatively to 6 months post-ACLR than the Low group (P = 0.003). Preoperative ACL-RSI scores increased significantly to 6 months post-ACLR in the entire group of participants (P < 0.001) and in the High group (P < 0.001). However, in the Low group, ACL-RSI scores did not increase significantly (P = 0.714).ConclusionsParticipants with low ACL-RSI scores 6 months post-ACLR had low preoperative ACL-RSI scores that did not improve preoperatively to 6 months post-ACLR.     

Age,rehabilitation and surgery characteristics are re-injury risk factors for adolescents following anterior cruciate ligament reconstruction

ObjectivesTo examine the effect of age on post-ACLR rehabilitative outcomes and identify surgical/rehabilitative characteristics as ACL re-injury risk factors in adolescents.DesignCohort study.SettingChildren’s hospital.Participants273 adolescents with first-time ACLR.Main outcome measuresDemographics, injury history, surgery, and outcomes documented during post-ACLR physical therapy (PT) sessions were extracted from medical records. Effects of age on outcomes were examined using multivariate regression. ACL re-injury risk factors were identified using survival analysis with Cox regression.ResultsRe-injury was recorded in 47 patients (17.2%) with a median follow-up time of 3.1 years and median re-injury time of 13.4 months post-surgery. Younger age (Hazard-Ratio, HR = 1.264 per year decrease; P = 0.005), receiving surgery within 1 month post-injury (HR = 3.378 vs. >3 months; P = 0.012), starting PT within 3 days post-surgery (HR = 3.068; P = 0.022), and decreased number of PT sessions (HR = 1.118 per 3-session decrease; P = 0.010) increased re-injury risk. Although age was associated with re-injury risk, age was not associated with any outcome (P > 0.059).ConclusionAdolescents who are younger, receive surgery and post-surgery PT sooner, or attend fewer PT sessions may be at an increased re-injury risk. Younger patients achieved similar outcomes despite elevated re-injury risk. Current discharge criteria are inadequate in identifying high re-injury risk patients.     

Preoperative quadriceps strength as a predictor of return to sports after anterior cruciate ligament reconstruction in competitive athletes

ObjectivesTo determine whether preoperative quadriceps strength predicts the likelihood of return to sports (RTS) following anterior cruciate ligament reconstruction (ACLR) in competitive athletes.DesignCase-control study.SettingSingle-center.ParticipantsA total of 221 competitive athletes who underwent primary ACLR were followed and divided into RTS (n = 177) and non-RTS (n = 44) groups based on self-reported sports activities at one year postoperatively.Main outcome measuresIsokinetic quadriceps strength tests were performed preoperatively and at six months and one year postoperatively, and the quadriceps index (QI) was calculated. Functional performance was evaluated by the single-leg hop (SLH) test at six months postoperatively.ResultsPreoperative QI significantly predicted the likelihood of RTS (odds ratio, 1.68 per 10-unit increase; P < 0.001), with a preoperative QI cut-off of 66% (AUC: 0.74; sensitivity: 68.9%; specificity: 77.3%). Subjects with a preoperative QI < 66% had a significantly lower postoperative QI, SLH, and rates of RTS compared to those with a higher preoperative QI (P < 0.01).ConclusionsPreoperative quadriceps strength could predict the likelihood of RTS following ACLR, and a preoperative QI < 66% was associated with a greater risk of unsuccessful RTS at one year postoperatively. Preoperative QI should be evaluated as a predictor of RTS.     

Quantifying the relationship between quadriceps strength and aerobic fitness following anterior cruciate ligament reconstruction

ObjectiveTo quantify the relationship between quadriceps strength and aerobic fitness following ACLR.Methods42 individuals with ACLR (29F/13M, 20.2 ± 3.3years, 71.8 ± 17.4 kg, 171.1 ± 9.4 cm, 21.9 ± 21.5months post-surgery) and 38 healthy controls (24F/14M, 20.1 ± 1.4years, 69.8 ± 10.2 kg, 172.9 ± 8.7 cm) completed quadriceps strength testing using an instrumented dynamometer then completed an incremental treadmill test to determine aerobic fitness (VO₂max). Bivariate Pearson's correlations were calculated between strength and VO₂max. Significant correlations were retained for a regression analysis.ResultsHealthy controls demonstrated significantly greater VO₂max compared to the ACLR group (d = 0.56). Unilateral strength variables were significantly correlated with VO₂max (P ≤ 0.006) for both groups. Normalized peak isokinetic knee extensor torque was retained in the model, which explained 20.5% of the variance in healthy VO₂max and 37.2% of the variance in ACLR VO₂max.ConclusionsAerobic fitness was reduced in the ACLR group in comparison to the healthy controls, despite unrestricted return to activity and similar activity levels between groups. Unilateral quadriceps strength was significantly correlated with aerobic fitness, which may be an indicator that greater unilateral strength may be a proxy for assessing aerobic fitness. Furthermore, sports medicine professionals may consider incorporating techniques and exercises during rehabilitation to improve cardiovascular fitness following ACLR.     

Knee strength outcomes in adolescents by age and sex during late-stage rehabilitation after anterior cruciate ligament reconstruction

ObjectiveTo determine if knee strength differences exist according to age group and sex among adolescents during late-stage anterior cruciate ligament reconstruction (ACLR) rehabilitation.DesignRetrospective cohort study.MethodsConsecutive patients who had undergone ACLR with a hamstring autograft completed isokinetic knee strength assessment. Patients were categorized into early (ages 11–14 years) and middle (ages 15–17 years) adolescence. A two-way MANOVA was used to examine strength differences according to age group and sex.Results144 patients were included in the analysis (56.9% females, age = 15.3 ± 1.5 years; days since surgery = 228.2 ± 41.2). Differences in quadriceps peak torque were identified between age groups on the involved (p = 0.001) and uninvolved limbs (p < 0.001), however, no differences in quadriceps peak torque were found between age groups when normalized to body mass (p = 0.16–0.49). Differences between groups according to sex were identified for each strength outcome (p < 0.01), with decreased normalized quadriceps (12–13%) and hamstring (13–16%) peak torque for females. No interactions between age group and sex were noted, F(8, 133) = 1.48, p = 0.17.ConclusionEarly adolescents produced less quadriceps and hamstring peak torque compared to middle adolescents after ACLR. No differences were found between age groups when normalized to body mass.     

Rehabilitation after ACL injury and reconstruction from the patients’ perspective

ObjectivesTo describe and compare patients’ appraisal of the rehabilitation and adherence to the rehabilitation program after acute ACL injury treated with (ACLR) or without (non-ACLR) reconstruction.DesignProspective cohort study.Participants275 patients (143 females; mean age 25 ± 7 years) with acute ACL injury, of whom 166 patients had ACLR within 24 months.Main outcomeAdherence to rehabilitation was assessed using the modified Sports Injury Rehabilitation Adherence Scale (SIRAS).ResultsAppraisal of rehabilitation was higher in the post-ACLR group compared to the non-ACLR group at 3 months (91% compared to 70% scored rehabilitation as necessary, p = 0.025) and at 6 months (87% compared to 70% scored it as necessary, p = 0.017). SIRAS score did not differ between 3 and 6 months for the non-ACLR group (median (IQR) 13 (2) vs 13 (2)) or the post-ACLR group (14 (1) vs 14 (2), p > 0.05). The post-ACLR group had a higher SIRAS score than the non-ACLR group at 3 and 6 months (p ≤ 0.001).ConclusionPatients treated with ACLR reported valuing their rehabilitation more and rated greater adherence to the rehabilitation programme than non-surgically treated patients. As rehabilitation is essential for good knee function, strategies to improve adherence after non-ACLR treatment should be implemented.Level of evidenceProspective cohort study, level II.     

Effects of cognitive- and motor-dual tasks on postural control regularity following anterior cruciate ligament reconstruction

BackgroundHigh injury rates following anterior cruciate ligament reconstruction (ACLR) motivate the need to better understand lingering movement deficiencies following return to sport. Athletic competition involves various types of sensory, motor, and cognitive challenges; however, postural control deficiencies during this spectrum of conditions are not well understood following ACLR.Research questionTo what extent is postural control altered following ACLR in the presence of sensory, motor, and cognitive challenges, and does postural control correlate with patient-reported symptoms?MethodsFourteen individuals following ACLR (4 m/10 f, 21.2 ± 2.4 yr, 76.9 ± 19.1 kg, 1.70 ± 0.14 m) and fourteen matched healthy controls (4 m/10 f, 21.2 ± 1.4 yr, 75.4 ± 15.3 kg, 1.70 ± 0.15 m) participated in the study. Participants completed single-leg balance, ACLR limb or matched side for controls, under four conditions: 1) eyes open, 2) eyes closed, 3) visual-cognitive dual task (i.e., reverse digit span), and 4) motor dual task (i.e., catching a ball). Sample entropy (SEn) was calculated for each balance condition to characterize regularity of center of pressure control. Participants also completed patient-reported outcomes to characterize self-reported knee function, symptoms, and fear. A mixed effects model tested for differences in SEn between balance conditions, and Spearman correlations tested for relationships between SEn and patient-reported outcomes.ResultsA significant Group-by-Condition interaction was detected (P = 0.043). While the motor dual task and eyes closed balance conditions were associated with the lowest SEn for both groups, only the visual-cognitive dual task condition demonstrated a significant difference between groups, with the ACLR group having lower SEn [95% confidence interval for ΔSEn: (0.03, 0.35)]. Lower KOOS-Sport scores were associated with decreased SEn for the ACLR group (ρ = 0.81, P < 0.001).SignificanceThese findings are consistent with ACLR individuals using a less automatic approach to postural control compared to controls, particularly when presented with a visual-cognitive challenge. Altered neuromuscular control persists well after ACLR surgery and can be related to patient-reported outcomes.     

Changes in stair ascent biomechanics two to eight years after ACL reconstruction are associated with patient-reported outcomes

BackgroundAnterior cruciate ligament (ACL) injury is often followed by quadriceps deficits that are apparent with gait analysis. The deficit frequently remains after ACL reconstruction (ACLR). As such, evaluation of ACLR patients could be enhanced by a simple method to detect quadriceps deficits. Analyzing forward trunk flexion during stair ascent has been suggested as an assessment of quadriceps function that can be visualized with relatively simple instrumentation.AimThe purpose of this study was to determine if trunk flexion angle (TFA) during stair ascent is associated with quadriceps function (as measured by the peak knee flexion moment (KFM)) at 2 and 8 years post-ACLR and if changes are associated with patient-reported outcomes (PRO).MethodsFourteen subjects with unilateral primary ACLR performed three stair-ascending trials at two-time periods: 2 years (baseline) and 8 years (follow-up) post-ACLR. Paired Student t-tests determined differences in KFM and TFA. Associations between KFM, TFA, and PRO were determined through Pearson correlations.ResultsPeak KFM during stair ascent significantly increased from baseline to follow-up (p = 0.01). Though there was no significant difference in TFA (p = 0.84) compared to baseline, 50% of subjects showed decreases in TFA. Further, subjects with reduced TFA during stair ascent at follow-up had significantly increased peak KFM (p = 0.029) and improvements in PRO (p = 0.001).DiscussionThe results suggest that TFA during stair ascent can provide a simple method to assess changes in quadriceps function and pain over time following ACLR. Further analysis is needed to draw conclusions between knee osteoarthritis development and increases in TFA.     

Current perspectives of New Zealand physiotherapists on rehabilitation and return to sport following anterior cruciate ligament reconstruction: A survey

ObjectiveTo investigate the clinical beliefs and practices of New Zealand physiotherapists regarding pre- and post-surgical rehabilitation and return to sport (RTS) criteria following anterior cruciate ligament reconstruction (ACLR).DesignOnline cross-sectional survey.MethodsA survey was adapted from a previously published survey and disseminated to New Zealand physiotherapists who were considered more likely to be involved in post-ACLR rehabilitation.ResultsThe number of completed surveys was 318. Most physiotherapists (85%) preferred to first consult patients within 14 days of ACLR. In the first six weeks following ACLR, 89% of physiotherapists see patients at least once per week. Between 3- and 6-months post-ACLR, 76% of physiotherapists see patients at least once a fortnight. Pre-operative rehabilitation and post-operative rehabilitation exceeding six months are considered essential or important to patient outcomes by over 95% of physiotherapists. While 63% of physiotherapists support RTS 9–12 months after ACLR, 11% permit RTS within 6–9 months of surgery. Common RTS considerations include functional capacity, movement quality during functional tasks, time from ACLR, and knee strength.ConclusionThe survey revealed variability in the beliefs and practices of NZ physiotherapists regarding post-ACLR rehabilitation, and these beliefs and practices are at times inconsistent with best practice recommendations.     

Inertial sensors identified asymmetries in shank angular velocity at different gait speeds in individuals with anterior cruciate ligament reconstruction

BackgroundInertial sensors can detect between-limb asymmetries in shank angular velocity (SAV) during loading response of walking in individuals with ACL reconstruction (ACLR), which may be indicative of abnormal knee joint loading. However, it is unknown whether these SAV asymmetries would exist up to 6 months post-ACLR and how they differ from SAV asymmetries in uninjured healthy subjects.Research questionTo investigate whether patients with ACLR show significant and meaningful between-limb SAV asymmetries during walking and walking fast at 4 and 6 months post-surgery and to determine whether limb asymmetries are related across gait tasks and time.MethodsFifteen individuals with ACLR participated in this prospective study. Testing occurred in clinical settings. Participants were instructed to walk and walk fast while wearing one inertial sensor on each shank. The average of sagittal plane SAV peaks during loading response of gait was calculated bilaterally. The smallest meaningful between-limb difference for SAV was calculated from uninjured healthy subjects (n = 16) to define the limit of meaningful SAV asymmetries in patients with ACLR.ResultsAt 4 and 6 months post-ACLR, the involved limb had significantly smaller peak SAV during walking (P < .01, d = 0.69−0.85) and walking fast (P < .005, d = 1.03−1.07) compared to the uninvolved limb. A significant main effect of gait task on SAV asymmetries was found (P = .006, η_p² = 0.451). Further, patients with ACLR exhibited meaningful SAV asymmetries at both time points for both gait speeds. Limb SAV asymmetries correlated between gait tasks and across time (r = 0.760−0.860, P < .001).SignificanceIndividuals with ACLR presented with significant and meaningful SAV asymmetries during walking and walking fast at 4 and 6 months post-surgery. Greater limb SAV asymmetries persisted across gait tasks and time, with greater asymmetry was observed at a faster walking speed. Thus, inertial sensors are feasible to be used in clinical settings to identify SAV asymmetry during gait post-ACLR.     

Low knee-related quality of life and persistent physical asymmetries in participants up to 10 years post-ACL reconstruction – A cross-sectional study

ObjectiveTo compare self-report and functional outcomes between participants with anterior cruciate ligament reconstruction (ACLR) with age and activity matched controls.DesignCross-sectional study.SettingUniversity laboratory-based study.ParticipantsTwenty-five participants (30.8 ± 9.7 years; 13 women), two to ten years post anterior cruciate ligament reconstruction; 24 controls (31.0 ± 10 years, 13 women).Main outcome measuresKnee Osteoarthritis and Injury Outcome Score (KOOS), Tegner, Marx Activity and Fear of Re-injury scales, and SF-12; isokinetic quadriceps and hamstring peak torque and single-leg hop distance.ResultsThere were no between-groups differences for the Tegner and the Marx Activity Scales. The ACLR group had lower KOOS dimensions (p < 0.001), SF-12 Physical Component Scores (p = 0.008), and higher Fear of Reinjury Scores (<0.001) than the controls. No significant differences were found for physical performance measures between the ACLR and the control groups. Significant between-side differences for the ACLR group were evident for concentric quadriceps (p < 0.001) and concentric hamstring peak torque (p = 0.002), and hop distance (p < 0.001).ConclusionKnee-specific symptoms and function, activity and quality of life were lower, and fear of re-injury was higher for participants with ACLR than controls. Side-to-side thigh muscle strength and hop distance deficits were evident for the ACLR group.     

Assessing implementation,limited efficacy,and acceptability of the BEAST tool: A rehabilitation and return-to-sport decision tool for nonprofessional athletes with anterior cruciate ligament reconstruction

ObjectivesTo assess the implementation, limited efficacy, and acceptability of the BEAST (better and safer return to sport) tool – a rehabilitation and return-to-sport (RTS) decision tool after anterior cruciate ligament reconstruction (ACLR) in nonprofessional athletes.DesignProspective cohort.Participants43 nonprofessional pivoting sport athletes with ACLR.Main outcomeClinician- and athlete-experienced implementation challenges (implementation), changes in quadriceps power, side hop and triple hop performance from 6 to 8 months after ACLR (limited efficacy), athletes’ beliefs about the individual rehabilitation and RTS plans produced by the BEAST tool (acceptability).ResultsThe BEAST tool was developed and then implemented as planned for 39/43 (91%) athletes. Hop and quadriceps power performance improved significantly, with the largest improvement in involved quadriceps power (standardised response mean 1.4, 95% CI:1.1–1.8). Athletes believed the rehabilitation and RTS plan would facilitate RTS (8.2 [SD: 2.0]) and reduce injury risk (8.3 [SD: 1.2]; 0 = not likely at all, 10 = extremely likely).ConclusionThe BEAST tool was implemented with few challenges and adjustments were rarely necessary. Athletes had large improvements in quadriceps power and hop performance on the involved leg. Athletes believed that the individual rehabilitation and RTS plans produced by the tool would facilitate RTS and reduce injury risk.     

Type of measurement used influences central and peripheral contributions to quadriceps weakness after anterior cruciate ligament (ACL) reconstruction

ObjectiveThe relative contribution of muscle size and voluntary activation (VA) on quadriceps strength after anterior cruciate ligament (ACL) reconstruction remains inconclusive. Here, we aimed to determine the contributions of muscle size and VA on quadriceps strength in ACL-reconstructed patients and determine if contributions were similar if unilateral outcomes (i.e. ACL-reconstructed limb) or the LSI was used. Design: A cross-sectional study.SettingA university research laboratory.ParticipantsSixteen individuals 6–12 months after ACL reconstruction (Age: 22.3 ± 6.0yr, Height: 1.7 ± 0.1 m, Mass: 68.7 ± 11.5 kg) were recruited.Main outcome measuresQuadriceps isometric strength and VA, via the interpolated triplet technique, were assessed bilaterally. Ultrasound images were acquired of the vastus lateralis to calculate cross-sectional area (CSA) in both legs. LSI’s were computed for all variables by expressing values of the reconstructed leg as a percent of the non-reconstructed leg. Separate stepwise linear regressions were performed to examine the contribution of VA and CSA on quadriceps strength. Model 1 used LSI for all outcomes and model 2 used outcomes from the reconstructed leg.ResultsWe observed between limb deficits of 27.78% in quadriceps strength, 13.61% in vastus lateralis CSA, and 13.18% in VA (P < 0.05). Strength LSI was significantly predicted by VA LSI (R² = 0.45, P < 0.01), but not by CSA LSI (R² = 0.01, P =0.87). Reconstructed leg strength was significantly predicted by VL CSA (R² = 0.50, P < 0.01) but not quadriceps VA (R² = 0.08, P =0.11).ConclusionsThe contributions of VA and CSA on quadriceps PT differed greatly if LSI or reconstructed leg outcomes were used. Evaluation of VA and CSA in unison may be provide a more holistic understanding of the sources of muscle weakness after ACL reconstruction.     

Commonly used clinical criteria following ACL reconstruction including time from surgery and isokinetic limb symmetry thresholds are not associated with between-limb loading deficits during running

ObjectivesWe included objective measures of gait and functional assessments to examine their associations in athletes who had recently commenced running after ACL reconstruction.DesignCross-sectional.SettingSports medicine.Participants65 male athletes with a history of ACL reconstruction.Main outcome measuresTime from surgery, isokinetic knee extension/flexion strength (60°/s), and peak vertical ground reaction force (pVGRF) measured during running using an instrumented treadmill. We also investigated if a range of recommended isokinetic thresholds (e.g. > 70% quadriceps limb symmetry index) affected the magnitude of pVGRF asymmetry during running.ResultsThere were significant relationships between quadriceps (r = 0.50) and hamstrings (r = 0.46) peak torque and pVGRF. Quadriceps peak torque explained a quarter of the variance in pVGRF (R² = 0.24; p < 0.001). There was no association was between running pVGRF and time from surgery. Between-group differences in running pVGRF LSI% were trivial (d < 0.20) for all quadriceps and hamstring peak torque LSI thresholds.ConclusionsCurrent clinical criteria including time from surgery and isokinetic strength limb symmetry thresholds were not associated with lower pVGRF asymmetry measured during running. Quadriceps strength is important, but ‘minimum symmetry thresholds’ should be used with caution.     

Does a knee joint position sense test make functional sense? Comparison to an obstacle clearance test following anterior cruciate ligament injury

ObjectivesTo evaluate knee joint position sense (JPS) among individuals with anterior cruciate ligament reconstruction (ACLR), cleared for return to sport, and investigate whether JPS errors are associated with outcomes of a functional obstacle clearance test (OC; downward vision occluded).DesignCross-sectional.SettingControlled laboratory.ParticipantsThirty-four individuals following ACLR, 23 non-athletic asymptomatic controls (CTRL), 18 athletes (ATH).Main outcome measuresabsolute error (AE) and variable error (VE) for weight-bearing knee JPS (target angles: 40°, 65°); minimal distances of the lower extremity from the obstacle (at any time and vertical clearance; two obstacle heights).ResultsLarger AE (P = 0.023) and VE (P = 0.010) were observed for CTRL compared with ACLR. CTRL also had larger OC distances for the trailing leg compared with ATH (P ≤ 0.046) and greater variability compared to both other groups (P ≤ 0.033). Moderate positive correlations (R_s ≥ 0.408, P ≤ 0.029) were observed between AE for the 40° angle and low-obstacle distances, for the injured ACLR leg.ConclusionsKnee JPS was worse in less-active individuals rather than following ACLR. Functional assessments like our OC test should complement isolated JPS tests, as they emphasize whole-body coordination and thus constitute more relevant estimations of proprioception.