Anterior Cruciate Ligament Reconstruction Limb Research Articles

Lower extremity joint angle, moment, and coordination throughout a double limb drop vertical jump in individuals with anterior cruciate ligament reconstruction

ABSTRACT Individuals with anterior cruciate ligament reconstruction (ACLR) utilise different landing biomechanics between limbs, but previous analyses have not considered the continuous or simultaneous joint motion that occurs during landing and propulsion. The purpose of this study was to compare sagittal plane ankle/knee and knee/hip coordination patterns as well as ankle, knee, and hip angles and moments and vertical ground reaction force (vGRF) between the ACLR and uninjured limbs during landing and propulsion. Fifteen females and thirteen males performed a drop vertical jump from a 30 cm box placed half their height from force platforms. Coordination was compared using a modified vector coding technique and binning analysis. Kinematics and kinetics were time normalised for waveform analyses. Coordination was not different between limbs. The ACLR limb had smaller dorsiflexion angles from 11 to 16% of landing and 24 to 75% of landing and propulsion, knee flexion moments from 5 to 15% of landing, 20 to 31% of landing, and 35 to 91% of landing and propulsion, and vGRF from 92 to 94% of propulsion compared with the uninjured limb. The ACLR limb exhibited smaller dorsiflexion angles to potentially reduce the knee joint moment arm and mitigate the eccentric and concentric demands on the ACLR knee during landing and propulsion, respectively.

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

The capacity to explosively contract quadriceps within the critical timeframe associated with anterior cruciate ligament (ACL) injury, quantified by the rate of torque development, is potentially essential for safe landing mechanics. This study aimed to investigate the influence of explosive quadricepsstrength on ACL-related sagittal-plane landing mechanics in females with and without ACL reconstruction (ACLR). Quadricepsexplosive strength and landing mechanics were assessed in 19 ACLR and 19 control females during isometric contractions and double-and single-leg jump landings. A stepwise multiple linear regression model determined the variance in each of the landing biomechanics variables for the ACLR limb and nondominant limb of controls that could be explained by the group, rate of torque developmentand/or their interaction. If peak kinetic variables could be predicted by the rate of torque development or interaction, additional analyses were conducted, accounting for knee flexion as a covariate in the regression model. During single-leg landings, ACLR females exhibited greater knee flexion at initial contact than controls (p = 0.04). Greater quadricepsrate of torque development predicted higher peak posterior ground reaction force and anterior tibial shear force in both groups (p = 0.04). However, after controlling for knee flexion angle at those peak forces, quadriceps rate of torque development was not predictive. In double-leg landings, greater explosive quadriceps strength was associated with quicker attainment of peak knee extension moment and posterior ground reaction force in the ACLR limb (p = 0.03). Regardless of ACL injury status, females with greater explosive quadriceps strength adopted safer single-leg landings through increased knee flexion, potentially mitigating ACL loading despite encountering higher peak forces. During double-leg landings, a greater explosive quadriceps strength of the ACLR limb is associated with faster achievement of peak force upon landing. Incorporating explosive quadriceps strengthening into post-ACLR rehabilitation and injury prevention programmes may enhance landing mechanics for reducing primary and subsequent ACL injury risks. Level II.

Moment arm and torque generating capacity of semitendinosus following tendon harvesting for anterior cruciate ligament reconstruction: A simulation study.

Altered semitendinosus (ST) morphology and distal tendon insertion following anterior cruciate ligament reconstruction (ACLR) may reduce knee flexion torque generating capacity of the hamstrings via impaired ST force generation and/or moment arm. This study used a computational musculoskeletal model to simulate mechanical consequences of tendon harvest for ACLR on ST function by modeling changes in ST muscle tendon insertion point, moment arm, and torque generating capacity across a physiological range of motion. Simulated ST function was then compared between ACLR and uninjured contralateral limbs. Magnetic resonance imaging from 18 individuals with unilateral history of ACLR involving a hamstring autograft was used to analyse bilateral hamstring muscle (ST, semimembranosus, bicep femoris long head and short head) morphology and distal ST tendon insertion. The ACLR cohort was sub-grouped into those with and without ST regeneration. For each participant with ST regeneration (n = 7), a personalized musculoskeletal model was created including postoperative remodeling of ST using OpenSim 4.1. Knee flexion and internal rotation moment arms and torque generating capacities of hamstrings were evaluated. Bilateral differences were calculated with an asymmetry index (%) ([unaffected limb-affected limb]/[unaffected limb + affected limb]*100%). Smaller moment arms or knee torques within injured compared to uninjured contralateral limbs were considered a deficit. Compared to uninjured contralateral limbs, ACLR limbs with tendon regeneration (n = 7) had minor reductions in knee flexion (5.80% [95% confidence interval (CI) = 3.97-7.62]) and internal rotation (4.92% [95% CI = 2.77-7.07]) moment arms. Decoupled from muscle morphology, altered ST moment arms in ACLR limbs with tendon regeneration resulted in negligible deficits in knee flexion (1.20% [95% CI = 0.34-2.06]) and internal rotation (0.24% [95% CI = 0.22-0.26]) torque generating capacity compared to uninjured contralateral limbs. Coupled with muscle morphology, ACLR limbs with tendon regeneration had substantial deficits in knee flexion (19.32% [95% CI = 18.35-20.28]) and internal rotation (15.49% [95% CI = 14.56-16.41]) torques compared to uninjured contralateral limbs. Personalized musculoskeletal models with measures of ST distal insertion and muscle morphology provided unique insights into post-ACLR ST and hamstring function. Deficits in knee flexor and internal rotation moment arms and torque generating capacities were evident in those with ACLR even when tendon regeneration occurred. Future studies may wish to implement this framework in personalized musculoskeletal models following ACLR to better understand individual muscle function for injury prevention and treatment evaluation.

Lower-Extremity Visuomotor Reaction Time Is Not Different Between Males and Females Following Anterior Cruciate Ligament Reconstruction

Visuomotor reaction time (VMRT) is predictive of lower-extremity musculoskeletal injury and may be a modifiable anterior cruciate ligament (ACL) injury risk factor that affects the incidence of primary and secondary ACL injuries in females. However, it is unknown if females with ACL reconstruction (ACLR) experience diminished VMRT compared with their male counterparts. The purpose of this study was to compare lower-extremity VMRT (LEVMRT) between males and females with ACLR. Female (n = 40) and male (n = 20) participants who were between 4 and 12 months after primary, unilateral ACLR completed a LEVMRT task with each limb using a series of wireless light discs. Mann–Whitney U tests were used to compare between-group differences for LEVMRT (in milliseconds). No statistically significant sex differences were observed for LEVMRT when the ACLR limb deactivated the light discs (females = 509.5 [132.5], males = 507.0 [79.8]; p = .77) or when the ACLR limb was stabilizing while the nonsurgical limb deactivated the light discs (females = 528.5 [105.3], males = 546.0 [92.5]; p = .77). Both males and females may benefit from visual motor training to improve VMRT after ACLR.

Sensorimotor Dysfunction Following Anterior Cruciate Ligament Reconstruction- an Afferent Perspective: A Scoping Review.

Sensorimotor dysfunction is thought to occur following anterior cruciate ligament (ACL) injury which may have implications on future reinjury risk. Dysfunction has been demonstrated within the efferent component of the sensorimotor system. However, no reviews have examined the two main components of the afferent system: the visual and somatosensory systems. This study aimed to report differences in function (central processing and local processing) within the (1) somatosensory and (2) visual systems between individuals following anterior cruciate ligament reconstruction (ACLR) and healthy controls (between-subject). The study also aimed to report differences in function within the two systems between the two limbs of an individual following ACLR (within-subject). Scoping review. A search was conducted in PubMed, SPORTDiscus, CINAHL, Medline and Embase up until September 2021. Level I-IV studies assessing somatosensory and visual systems were included if they compared ACLR limbs to the uninjured contralateral limb (within-subject) or a healthy control limb (between-group). The function of somatosensory and visual systems was assessed across both central processing (processing of information in the central cortex) and local processing (all other assessments outside of central processing of information). Seventy studies were identified (52 somatosensory, 18 visual). Studies examining somatosensory central processing demonstrated significant differences; 66% of studies exhibited within-subject differences and 100% of the studies exhibited between-group differences. Studies examining local somatosensory processing had mixed findings; 40% of the 'joint position sense (JPS)' and 'threshold to detect motion (TTDM)' studies showed significant within-subject differences (JPS=0.8°-3.8° and TTDPM=0.2°-1.4°) and 42% demonstrated significant between-group differences (JPS=0.4°-5° and TTDPM=0.3°-2.8°). Eighty-three percent of visual central processing studies demonstrated significant dysfunction between-groups with no studies assessing within-subject differences. Fifty percent of the studies examining local visual processing demonstrated a significant between-group difference. Significant differences in central processing exist within somatosensory and visual systems following ACLR. There is mixed evidence regarding local somatosensory and visual processing. Increased compensation by the visual system and local visual processing dysfunction may occur in conjunction with somatosensory dysfunction.

The Influence of Knee Position on Ultrasound Imaging of Femoral Cartilage in Individuals with Anterior Cruciate Ligament Reconstruction.

Articular cartilage is important for knee function and can be imaged using ultrasound. The purpose was to compare femoral cartilage thickness and echo intensity (EI) measured at 90° and 140° of knee flexion and between limbs in a cohort with unilateral anterior cruciate ligament reconstruction (ACLR). We also examined associations between gait biomechanics and cartilage outcomes. Twenty-seven individuals with primary unilateral ACLR participated (12 men, 15 women; age = 22.3 ± 3.8 years; time since ACLR = 71.2 ± 47.2 months). Ultrasound was used to obtain femoral cartilage measurements. Gait outcomes included peak KFA (knee flexion angle) and peak external knee flexion moment (KFM). Cartilage outcomes were compared using a 2 (position) × 2 (limb) repeated measures ANOVA (analysis of variance). Gait and cartilage associations were assessed using linear regression. There were no position × limb interactions for any cartilage outcome (all P > 0.05). Medial (P = 0.038) and central cartilage (P < 0.001) were thicker, whereas central (P = 0.029) and lateral cartilage EI (P = 0.003) were lower when measured at 90° than those at 140° of knee flexion. Medial cartilage was thicker in the ACLR than that in the contralateral limb (P = 0.016). A larger KFM was associated with thicker medial cartilage (ΔR2 = 0.146, P = 0.021) and central cartilage (ΔR2 = 0.159, P = 0.039) measured at 140° of knee flexion in the ACLR limb but not at 90°. Findings suggest that imaging position influences cartilage thickness and EI measurements in individuals with ACLR and should be considered in study designs and clinical evaluation. A greater KFM was associated with thicker cartilage within specific portions of the distal femur.

Cartilage deformation following a walking bout in individuals with anterior cruciate ligament reconstruction.

The purpose was to (1) compare the effect of a walking bout on femoral cartilage deformation between limbs with and without anterior cruciate ligament reconstruction (ACLR) and (2) examine the association between gait kinetics and the magnitude of cartilage deformation. A total of 30 individuals with primary unilateral ACLR completed this study [14 male, 16 female; age = 22.57 (3.78) years; body mass index (BMI) = 25.88 (5.68) kg/m2 ; time since ACLR = 61.00 (16.43) months]. Overground walking biomechanics were assessed on day 1, and a 30-min walking bout or 30-min resting bout (control) were completed on days 2 and 3 (counterbalanced order). Femoral cartilage thickness was measured using ultrasound before, immediately following, and 30-min following each intervention. Linear mixed effects models compared the effect of walking on cartilage thickness between the ACLR and contralateral limbs after adjusting for sex, BMI, speed, and the number of steps. Stepwise regression examined the association between the external knee flexion and adduction moments and cartilage deformation following walking. There was a significant limb × time interaction for medial cartilage thickness. Post hoc analyses indicated that cartilage thickness decreased immediately following walking in the contralateral but not ACLR limb. Main effects of limb were observed for medial, central, and lateral cartilage thickness indicating thicker cartilage in the ACLR compared with contralateral limb. A higher knee adduction moment was associated with greater cartilage deformation in the ACLR limb. Femoral cartilage in the ACLR limb exhibited a less dynamic response to walking than the uninvolved limb, which may be due to habitual underloading during gait.

Does the one-leg rise test reflect quadriceps strength in individuals following anterior cruciate ligament reconstruction?

ObjectiveTo explore if one-leg rise test performance is associated with quadriceps strength following anterior cruciate ligament reconstruction (ACLR). DesignCross-sectional. Participants100 individuals (50 females, 50 males) aged 18–40 years, 9–36 months post-ACLR with ongoing knee symptoms (KOOS4 <80/100). Main outcome measuresNumber of one-leg rise repetitions (using an adjustable-height plinth) and isometric quadriceps strength using isokinetic dynamometry (60° flexion, normalised to body mass). Multivariable fractional polynomial regression models adjusted for sex explored relationships between one-leg rise performance (repetitions) and quadriceps strength (Nm/kg) for each limb. ResultsA non-linear, increasing association between one-leg rise performance and quadriceps strength was observed, with the rate of increase attenuating at higher values of one-leg rise performance. Similar relationships were observed in the ACLR (β = 0.15, 95%CI 0.10 to 0.20; adjusted r2 = 0.51) and contralateral limb (β = 0.14, 95%CI 0.08 to 0.19; r2 = 0.42). ConclusionThe one-leg rise test can be an indicator of quadriceps strength in individuals after ACLR, enabling clinicians to easily monitor quadriceps strength recovery without specialised equipment. With the relationship between one-leg rise performance and quadriceps strength attenuating with a larger number of one-leg rises achieved, other factors (e.g., motivation, endurance) likely contribute to one-leg rise performance at higher values.

The Impact of Meniscal Tear Type and Surgical Treatment on Quadriceps Strength: A Study of Adolescent Patients Post Anterior Cruciate Ligament Reconstruction

Background: Treatment of meniscal injuries at the time of anterior cruciate ligament reconstruction (ACLR) can result in restrictions on weightbearing and range of motion in the early rehabilitative phases. What is unknown is the effect of (1) meniscal tear type and location at the time of anterior cruciate ligament injury and (2) meniscal treatment at the time of ACLR on quadriceps strength in adolescents during the late rehabilitative phase. Hypothesis: Meniscal tears involving the root and requiring repair would adversely affect quadriceps strength at 6 to 9 months postoperatively. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent ACLR at 1 of 2 research sites between 2013 and 2021 were identified. Adolescent participants were included if they were between the ages of 12 and 20 years at the time of assessment and had undergone primary unilateral ACLR in the previous 6 to 9 months. Participants were subgrouped by meniscal tear type (no tear, nonroot tear, root tear) and meniscal treatment at the time of ACLR (no treatment, meniscectomy, meniscal repair), which were confirmed via chart review. Isokinetic strength testing occurred at 60 deg/s, and quadriceps strength and quadriceps strength limb symmetry index were compared between the meniscal tear type and meniscal procedure subgroups using analysis of covariance while controlling for the effects of age, sex, and ACLR graft source. Results: An overall 236 patients were included in this analysis (109 male, 127 female; mean ± SD age, 16.0 ± 1.9 years). There were no significant differences in ACLR limb quadriceps strength based on meniscal tear type (P = .61) or meniscal procedure at the time of ACLR (P = .61), after controlling for age, biological sex, and ACLR graft source. Similarly, quadriceps strength limb symmetry index did not differ by meniscal tear type (P = .38) or meniscal procedure at the time of ACLR (P = .40). Conclusion: Meniscal tear type and treatment at the time of ACLR did not affect quadriceps strength or quadriceps strength symmetry in adolescents 6 to 9 months after ACLR.

Comparison of Patient-Reported Outcomes, Strength, and Functional Performance in Primary Versus Revision Anterior Cruciate Ligament Reconstruction

Background: Clinical outcomes after revision anterior cruciate ligament reconstruction (ACLR) are not well understood. Hypothesis: Patients undergoing revision ACLR would demonstrate worse patient-reported outcomes and worse limb symmetry compared with a cohort undergoing primary ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: 672 participants (373 with primary ACLR, 111 with revision ACLR, and 188 uninjured) completed functional testing at a single academic medical center. Descriptive information, operative variables, and patient-reported outcomes (International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Tegner Activity Scale score) were assessed for each patient. Quadriceps and hamstring strength tests were conducted using a Biodex System 3 Dynamometer. Single-leg hop for distance, triple hop test, and the 6-m timed hop test were also assessed. Limb symmetry index (LSI) between the ACLR limb and contralateral limb was calculated for strength and hop testing. Normalized peak torque (N·m/kg) was calculated for strength testing. Results: No differences were found in group characteristics, excluding body mass (P < .001), or in patient-reported outcomes. There were no interactions between revision status, graft type, and sex. Knee extension LSI was inferior (P < .001) in participants who had undergone primary (73.0% ± 15.0%) and revision (77.2% ± 19.1%) ACLR compared with healthy, uninjured participants (98.8% ± 10.4%). Knee flexion LSI was inferior (P = .04) in the primary group (97.4% ± 18.4%) compared with the revision group (101.9% ± 18.5%). Difference in knee flexion LSI between the uninjured and primary groups, as well as between the uninjured and revision groups, did not reach statistical significance. Hop LSI outcomes were significantly different across all groups (P < .001). Between-group differences in extension in the involved limb (P < .001) were noted, as the uninjured group exhibited stronger knee extension (2.16 ± 0.46 N·m/kg) than the primary group (1.67 ± 0.47 N·m/kg) and the revision group (1.78 ± 0.48 N·m/kg). As well, differences in flexion in the involved limb (P = .01) were found, as the revision group exhibited stronger knee flexion (1.06 ± 0.25 N·m/kg) than the primary group (0.97 ± 0.29 N·m/kg) and the uninjured group (0.98 ± 0.24 N·m/kg). Conclusion: At 7 months postoperatively, patients who had undergone revision ACLR did not demonstrate inferior patient-reported outcomes, limb symmetry, strength, or functional performance compared with patients who had undergone primary ACLR. Patients who had undergone revision ACLR exhibited greater strength and LSI than their counterparts with primary ACLR, but these parameters were still inferior to those of uninjured controls.

Lower Patellofemoral Joint Contact Force During Side-Step Cutting After Return-to-Sports Clearance Following Anterior Cruciate Ligament Reconstruction

Background: Low patellofemoral joint (PFJ) contact force has been associated with PFJ osteoarthritis. Quadriceps force and knee flexion angles, which are typically altered after an anterior cruciate ligament reconstruction (ACLR), primarily influence PFJ contact forces. It is still inconclusive whether differences in PFJ contact forces are present during high knee flexion tasks such as side-step cutting after clearance to return to sports (RTS) after ACLR. Purpose: To explore PFJ contact forces in the ACLR limb and compare them with those of the contralateral and control limbs during side-step cutting tasks after clearance to RTS. Study Design: Controlled laboratory study. Methods: A total of 26 male athletes with ACLR who were previously cleared to RTS were matched with 23 healthy men serving as the control group. Three-dimensional motion capture and force plate data were collected while both groups performed anticipated side-step cutting tasks. Joint kinematics, kinetics, muscle forces, and PFJ contact forces were calculated using musculoskeletal modeling. Results: Peak PFJ force was lower in the ACLR limbs compared with the contralateral limbs (mean difference [MD], 5.89 body weight [BW]; 95% CI, 4.7-7.1 BW; P < .001) and the control limbs (MD, 4.44 BW; 95% CI, 2.1-6.8 BW; P < .001). During peak PFJ force, knee flexion angle was lower in ACLR limbs compared with the contralateral (MD, 4.88°; 95% CI, 3.0°-6.7°; P < .001) and control (MD, 6.01°; 95% CI, 2.0°-10.0°; P < .002) limbs. A lower quadriceps force compared with the contralateral (MD, 4.14 BW; 95% CI, 3.4-4.9 BW; P < .001) and control (MD, 2.83 BW; 95% CI, 1.4-4.3 BW; P < .001) limbs was also found. Conclusion: Lower PFJ contact forces and a combination of quadriceps force deficits and smaller knee flexion angle were found in the ACLR compared with the contralateral and control limbs even after clearance to RTS. Clinical Relevance: Despite rehabilitation and subsequent clearance to RTS, differences in PFJ contact forces are present after ACLR. Current rehabilitation and RTS battery may not be effective and sensitive enough to identify and address these differences.

Joint and Limb Loading during Gait in Adults with ACL Reconstruction: Comparison between Single-Step and Cumulative Load Metrics.

Individuals with anterior cruciate ligament reconstruction (ACLR) generally exhibit limb underloading behaviors during walking, but most research focuses on per-step comparisons. Cumulative loading metrics offer unique insight into joint loading as magnitude, duration, and total steps are considered, but few studies have evaluated if cumulative loads are altered post-ACLR. Here, we evaluated if underloading behaviors are apparent in ACLR limbs when using cumulative load metrics and how load metrics change in response to walking speed modifications. Treadmill walking biomechanics were evaluated in 21 participants with ACLR at three speeds (self-selected (SS); 120% SS and 80% SS). Cumulative loads per step and per kilometer were calculated using knee flexion and adduction moment (KFM and KAM) and vertical ground reaction force (GRF) impulses. Traditional magnitude metrics for KFM, KAM, and GRF were also calculated. The ACLR limb displayed smaller KFM and GRF in early and late stances, but larger KFM and GRF during midstance compared with the contralateral limb ( P < 0.01). Only GRF cumulative loads (per step and per kilometer) were reduced in the ACLR limb ( P < 0.01). In response to speed modifications, load magnitudes generally increased with speed. Conversely, cumulative load metrics (per step and per kilometer) decreased at faster speeds and increased at slow speeds ( P < 0.01). Patients with ACLR underload their knee in the sagittal plane per step, but cumulatively over the course of many steps/distance, this underloading phenomenon was not apparent. Furthermore, cumulative load increased at slower speeds, opposite to what is identified with traditional single-step metrics. Assessing cumulative load metrics may offer additional insight into how load outcomes may be impacted in injured populations or in response to gait modifications.

MECHANICAL CONSEQUENCES FOR KNEE FUNCTION FOLLOWING SEMITENDINOSUS TENDON HARVESTING FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Anterior cruciate ligament reconstruction (ACLR) using a semitendinosus (ST) autograft, with or without gracilis (GR), results in donor muscle atrophy and varied tendon regeneration. The effects of harvesting these muscles on muscle moment arm and torque generating capacity have not been well described. This study aimed to determine between-limb differences (ACLR vs uninjured contralateral) in muscle moment arm and torque generating capacity across a full range of hip and knee motions.A secondary analysis of magnetic resonance imaging was undertaken from 8 individuals with unilateral history of ST-GR ACLR with complete ST tendon regeneration. All hamstring muscles and ST tendons were manually segmented. Muscle length (cm), peak cross-sectional area (CSA) (cm2), and volume (cm3) were measured in ACLR and uninjured contralateral limbs. OpenSim was used to simulate and evaluate the mechanical consequences of changes in normalised moment arm (m) and torque generating capacity (N.m) between ACLR and uninjured contralateral limbs.Compared to uninjured contralateral limbs, regenerated ST tendon re-insertion varied proximal (+) (mean = 0.66cm, maximum = 3.44cm, minimum = −2.17cm, range = 5.61cm) and posterior (+) (mean = 0.38cm maximum = 0.71cm, minimum = 0.02cm, range = 0.69cm) locations relative to native anatomical positions. Compared to uninjured contralateral limbs, change in ST tendon insertion point in ACLR limbs resulted in 2.5% loss in peak moment arm and a 3.4% loss in peak torque generating capacity. Accounting for changes to both max isometric force and ST moment arm, the ST had a 14.8% loss in peak torque generating capacity.There are significant deficits in ST muscle morphology and insertion points following ST-GR ACLR. The ST atrophy and insertion point migration following ACLR may affect force transmission and distribution within the hamstrings and contribute to persistent deficits in knee flexor and internal rotator strength.

SHAPE DIFFERENCES IN THE SEMITENDINOSUS FOLLOWING TENDON HARVESTING FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Following anterior cruciate ligament reconstruction (ACLR) using a semitendinosus (ST) autograft measures such as length, cross-sectional area, and volume may not fully describe the effects of tendon harvest on muscle morphology as these discrete measures cannot characterize three-dimensional muscle shape. This study aimed to determine between-limb ST shape similarity and regional morphology in individuals with a unilateral history of ACLR using a ST graft, and healthy controls.A secondary analysis of magnetic resonance imaging was undertaken from 18 individuals with unilateral history of ST ACLR and 18 healthy controls. ST muscles were manually segmented, and shape similarity were assessed between limbs and groups using Jaccard index (0-1) and Hausdorff distance (mm). ST length (cm), peak cross-sectional area (CSA) (cm2), and volume (cm3) was compared between surgically reconstructed and uninjured contralateral limbs, and between the left and right limbs of control participants with no history of injury. Cohen's d was reported as a measure of effect size.Compared to healthy controls, the ACLR group had significantly (p&lt;0.001, d= −2.33) lower bilateral ST shape similarity. Furthermore, the deviation in muscle shape was significantly (p&lt;0.001, d= 2.12) greater in the ACLR group. Within the ACLR group, maximum Hausdorff distance indicated ST from the ACLR limb deviated (23.1±8.68 mm) from the shape of the healthy contralateral ST, this was observed particularly within the distal region of the muscle. Compared to the uninjured contralateral limb and healthy controls, deficits in peak cross-sectional area and volume in ACLR group were largest in proximal (p&lt;0.001, d= −2.52 to −1.28) and middle (p&lt;0.001, d= −1.81 to −1.04) regions.Findings highlight morphological features in distal ST not identified by traditional discrete morphology measures. ST shape was most different in the distal region of the muscle, despite deficits in CSA and volume being most pronounced in proximal and middle regions. ST shape following ACLR may affect force transmission and distribution within the hamstrings and contribute to persistent deficits in knee flexor and internal rotator strength.

THE DOSTAR STUDY: A DOUBLE-BLINDED, RANDOMIZED CONTROLLED TRIAL COMPARING DUAL OR SINGLE HAMSTRING TENDON ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Hamstring grafts have been associated with reduced strength, donor site pain and muscle strains following Anterior Cruciate Ligament Reconstruction (ACLR). Traditional graft fixation methods required both semitendinosus and gracilis tendons to achieve a graft of sufficient length and diameter, but newer techniques allow for shorter, broad single tendon grafts.This study seeks to compare the outcomes between Single Tendon (ST) and Dual Tendon (DT) ACLR, given there is no prospective randomised controlled trial (RCT) in the literature comparing outcomes between these options.In this ongoing RCT: (ANZ Clinical Trials Registry ACTRN126200000927921) patients were recruited and randomised into either ST or DT groups. All anaesthetic and surgical techniques were uniform aside from graft technique and tibial fixation. 13 patients were excluded at surgery as their ST graft did not achieve a minimum 8mm diameter. 70 patients (34 ST, 36DT) have been assessed at 6 months, using PROMS including IKDC2000, Lysholm and Modified Cincinnati Knee, visual analog scale for pain frequency (VAS-F) and severity (VAS-S), dedicated donor site morbidity score, KT-1000 assessment, and isokinetic strength.Graft diameters were significantly lesser in the ST group compared to the DT group (8.44mm/9.11mm mean difference [MD],-0.67mm; P&lt;0.001). There was a significant and moderate effect in lower donor site morbidity in the ST group compared to the DT group (effect size [ES], 0.649; P = .01). No differences between groups were observed for knee laxity in the ACLR limb (P=0.362) or any of the patient-reported outcome measures (P&gt;0.05). Between-group differences were observed for hamstrings strength LSI favouring the ST group, though these were small-to-moderate and non-significant (ES, 0.351; P = .147).ST (versus DT) harvest results in significantly less donor site morbidity and this is the first prospective RCT to determine this. There were no differences between ST and DT hamstring ACLR were observed in PROMs, knee laxity and hamstring strength. Younger female patients tend to have inadequate single tendon size to produce a graft of sufficient diameter, and alternative techniques should be considered. Further endpoints include radiological analysis, longer term donor site morbidity, revision rates and return to sport and will continue to be presented in the future.

Pain Early After Anterior Cruciate Ligament Reconstruction is Associated With 6-Month Loading Mechanics During Running.

Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown. Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs. Cohort pilot study. Level 3. A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed. KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment (R2 = 0.35;P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb (R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment (R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb. These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR. Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.

Association Between the Functional Movement Screen and Landing Kinematics in Individuals With and Without Anterior Cruciate Ligament Reconstruction

The purpose of this study was to compare functional movement screen (FMS) scores and drop vertical jump (DVJ) kinematics between those with and without anterior cruciate ligament reconstruction (ACLR), and to evaluate the association between FMS composite score and DVJ kinematics. Cross-sectional. Sixty individuals with and without a history of ACLR. Composite FMS score and the dorsiflexion, knee-flexion, hip-flexion, knee abduction, hip adduction, and trunk-flexion angles during a DVJ. The FMS scores did not differ between groups (P > .05). There were smaller peak and initial contact hip-flexion angles in the ACLR and contralateral limbs compared with controls, and smaller peak dorsiflexion angles in the ACLR compared with contralateral limbs (P < .05). Lower FMS score was associated with a smaller peak dorsiflexion angle, smaller peak knee-flexion angle, and larger peak knee abduction angle in the ACLR limb (ΔR2 = .14-.23); a smaller peak dorsiflexion angle and smaller peak knee-flexion angle in the contralateral limb (ΔR2 = .17-.19); and a smaller peak dorsiflexion angle, smaller peak knee-flexion angle, and larger peak knee abduction angle in the control limb (ΔR2 = .16-.22). The FMS scores did not differ between groups, but were associated with DVJ kinematics and should be a complementary rather than substitute assessment.

Association Between Biochemical Joint Tissue Response To Loading And Femoral Cartilage Composition After Knee Surgery

Serum cartilage oligomeric matrix protein (sCOMP) is used to measure acute biochemical joint tissue response to loading. Greater delayed sCOMP post-loading is linked to femoral cartilage thinning over 5 years. It remains unclear if sCOMP response to loading is associated with early femoral cartilage compositional changes linked to osteoarthritis development. PURPOSE: The purpose of this cross-sectional study was to estimate the associations between changes in sCOMP after a standardized walking protocol and femoral cartilage composition in individuals with anterior cruciate ligament reconstruction (ACLR). METHODS: Serum was collected before, immediately after, and 3.5 hours after a standardized 3,000 step walking protocol conducted at each participant’s self-selected speed (speed = 1.2 ± 0.1 m/s). sCOMP changes were calculated as the difference in concentrations from before to immediately and 3.5 hours after walking. Enzyme-linked immunosorbent assays were used to assess sCOMP (mean intra-assay variability = 15%). T1ρ relaxations times were collected bilaterally using magnetic resonance imaging and weightbearing portions of the cartilage were segmented into medial (MFC) and lateral (LFC) femoral condylar regions. Regional interlimb ratios were calculated by dividing mean T1ρ relaxation times in the ACLR limb by the non-injured limb. Greater T1ρ interlimb ratios were interpreted as lower proteoglycan density (worse cartilage composition) in the ACLR relative to the non-injured limb. Linear regressions were used to determine the association between change in sCOMP and T1ρ relaxation times after controlling for sex and months since surgery. RESULTS: 19 participants (9 male/10 female, 20.5 ± 4.1 years old, 24.8 ± 3.1 kg/m2 BMI, 7.3 ± 1.5 months since surgery) completed the study. Greater LFC T1ρ interlimb ratios were associated with greater increases in COMP at 3.5 hours (∆R2 = 0.28, p = 0.03), but not immediately (∆R2 = 0.08, p = 0.32) after walking. Associations between MFC T1ρ interlimb ratios and changes in sCOMP after walking were not statistically significant (p = 0.57-0.82). CONCLUSIONS: Delayed increases in sCOMP concentrations after walking may be more closely linked to deleterious cartilage metabolism and may be a better marker of early degenerative changes in knee joint health than acute changes.

More Regular Gait Patterns Associate With Worse Femoral Cartilage Composition Following Anterior Cruciate Ligament Reconstruction

Individuals with anterior cruciate ligament reconstruction (ACLR) exhibit more regular gait patterns, resulting in more rigid movements compared to controls. Aberrant joint loading post-ACLR is linked to worse T1ρ magnetic resonance imaging (MRI) relaxation times, an outcome associated with osteoarthritis development. Yet, it remains unknown if knee movement regularity during gait associates with knee cartilage composition in individuals with ACLR. PURPOSE: Determine the association between femoral articular cartilage T1ρ MRI relaxation times and knee joint movement regularity during gait. METHODS: T1ρ MRI and gait kinematics were collected in 20 participants with ACLR (13 Females; 21 ± 4 years old; 8 ± 1 months post-ACLR). Femoral articular cartilage from the ACLR and uninjured limbs was segmented into anterior, central, and posterior regions from the weightbearing portions of the medial and lateral condyles. Mean T1ρ relaxation times were extracted from the cartilage in each region and interlimb ratios were calculated (i.e., ACLR / uninjured limb). Greater interlimb T1ρ ratios were interpreted as lesser proteoglycan density (worse cartilage composition) in the injured limb compared to the uninjured limb. Knee kinematics were collected at a self-selected gait speed on a treadmill with an 8-camera 3D motion capture system. Frontal and sagittal plane knee kinematics were extracted, and sample entropy was used to calculate the degree of movement regularity (i.e., lower values reflect more regularity). Pearson’s product-moment correlations were conducted to determine the association between T1ρ and movement regularity variables. RESULTS: Greater frontal plane knee movement regularity associated with greater mean T1ρ interlimb ratios in the anterior portions of the lateral (r = -0.44, p = .04) and medial condyles (r = -0.47, p = .03). Greater sagittal plane kinematic regularity associated with greater mean T1ρ interlimb ratios in the anterior portion of the lateral condyle (r = -0.47, p = .03). CONCLUSION: Greater movement regularity was associated with less femoral articular cartilage proteoglycan density which is linked to early osteoarthritis development. We hypothesize that greater movement regularity contributes to less adaptable gait and more concentrated cartilage loading.

Lower-Limb Muscle Activity During Aquatic Treadmill Running in Individuals With Anterior Cruciate Ligament Reconstruction

While anterior cruciate ligament (ACL) tears are commonly managed with ACL reconstruction (ACL-R), 35% of ACL-R individuals fail to return to the preinjury elite sport level. Persistent neuromuscular deficits in the hamstrings and quadriceps have been observed. It has been proposed that aquatic therapy can be used to optimize neuromuscular control after ACL-R. (1)To compare muscle activity in ACL-R individuals during aquatic treadmill (ATM) running at different water depths and (2)to compare muscle activity during ATM running between ACL-R and healthy individuals. A total of 38 participants, including 18 ACL-R individuals (mean postoperative time [SD] = 25.8 [25.0] mo) and 20 healthy individuals were recruited. Muscle activity of biceps femoris (BF), rectus femoris (RF), tibialis anterior, and medial gastrocnemius during land treadmill and ATM running at mid-shin, mid-thigh, and waist levels were recorded using surface electromyography (sEMG). The sEMG signals of the selected muscles were normalized and expressed in % Maximal Voluntary Contraction (%MVC). Muscle activity of the ACL-R, ACL-contralateral, and healthy control limbs at different water depths was compared. Among the 3 groups, the ACL-R group demonstrated the most prominent percentage increase of 101.97% (P = .001) at mid-shin level, 139.66% (P = .001) at mid-thigh level, and 141.97% (P < .001) at waist level, respectively, in %MVC when compared to land. In the ACL-R group, muscle activity of BF in the stance phase (BFSt) was significantly higher than the control group on land at all water depths. Muscle activity of RF in the swing phase (RFSw) in the ACL-R group significantly increased in all water depths immersion when compared to land, respectively. This study showed an increasing trend in muscle activity of BFSt and RFSw in ACL-R individuals during ATM running at increased water depths. ATM running could be implemented as neuromuscular training in rehabilitation after ACL-R.