Activity-Dependent Compensation at the Hip and Ankle at 8 Years After the Reconstruction of Isolated and Combined Posterior Cruciate Ligament Injuries.

BACKGROUND: After posterior cruciate ligament reconstruction (PCLR), functional deficits at the knee can persist. It remains unclear if neighboring joints compensate for the knee during demanding activities of daily living. PURPOSE: To assess long-term alterations in lower limb mechanics in patients after PCLR. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 28 patients who had undergone single-bundle unilateral isolated or combined PCLR performed stair navigation, squat, sit-to-stand, and stand-to-sit tasks at 8.2 ± 2.2 years after surgery. Motion capture and force plates were used to collect kinematic and kinetic data. Then, 3-dimensional hip, knee, and ankle kinematic data of the reconstructed limb were compared with those of the contralateral limb using statistical parametric mapping. RESULTS: Side-to-side differences at the knee were primarily found during upward-driven movements at 8 years after surgery. The reconstructed knee exhibited lower internal rotation during the initial loading phase of stair ascent versus the contralateral knee (P = .005). During the sit-to-stand task, higher flexion angles during the midcycle (P = .017) and lower external rotation angles (P = .049) were found in the reconstructed knee; sagittal knee (P = .001) and hip (P = .016) moments were lower in the reconstructed limb than the contralateral limb. In downward-driven movements, side-to-side differences were minimal at the knee but prominent at the ankle and hip: during stair descent, the reconstructed ankle exhibited lower dorsiflexion and lower external rotation during the midcycle versus the contralateral ankle (P = .006 and P = .040, respectively). Frontal hip moments in the reconstructed limb were higher than those in the contralateral limb during the stand-to-sit task (P = .010); during squats, sagittal hip angles in the reconstructed limb were higher than those in the contralateral limb (P < .001). CONCLUSION: Patients after PCLR exhibited compensations at the hip and ankle during downward-driven movements, such as stair descent, squats, and stand-to-sit. Conversely, residual long-term side-to-side differences at the knee were detected during upward-driven movements such as stair ascent and sit-to-stand. CLINICAL RELEVANCE: After PCLR, side-to-side differences in biomechanical function were activity-dependent and occurred either at the knee or neighboring joints. When referring to the contralateral limb to assess knee function in the reconstructed limb, concentric, upward-driven movements should be prioritized. Compensations at the hip and ankle during downward-driven movements lead to biases in long-term functional assessments.

Gait kinematics of osteoarthritic knees after intra-articular viscosupplementation: A double-blinded randomized controlled trial.

BACKGROUND: The utilization of subjective questionnaires for assessing conservative treatment in knee osteoarthritis may present challenges in identifying differences due to inadequate statistical power. Objective tools, such as three-dimensional (3D) kinematic analysis, are accurate and reproducible methods. However, no high-quality studies assessing the effects of intra-articular viscosupplementation (VS) have been published. Therefore, the objective of the study was to evaluate gait kinematics of patients with advanced knee osteoarthritis after VS. METHODS: Forty-two patients were randomized to receive either VS or saline injection (placebo). They underwent 3D kinematic gait analysis before and at 1, 6, and 12 weeks after treatment and knee angles during stance phase were determined. Patients and the healthcare team responsible for data collection, processing, and analysis were blinded to group allocation. Between-group comparisons were conducted using linear mixed models. RESULTS: Compared with placebo, the VS increased the maximum knee extension (3.2° (0.7-5.7)) and decreased the maximum knee flexion (-3.6° (-6.1 to -1.2)) on the sagittal plane at 1 week. At 6 weeks, the VS group sustained a reduced maximum knee flexion (-2.6° (-5.2 to 0.0)). On the axial plane, the VS group demonstrated an increase in maximum internal rotation at 12 weeks (3.9° (0.3 to 7.7)). The VS group exhibited reduced single-leg stance time at 1 week and increased total stance time at 12 weeks. CONCLUSIONS: VS led to short- and long-term kinematic improvements in the sagittal and axial planes, leading to a gait pattern closer to that observed in individuals with less severe osteoarthritic knees.

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

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

Influence of Footwear Selection on Youth Running Biomechanics: A Pilot Study.

BACKGROUND: The relationship of running biomechanics, footwear, and injury has been studied extensively in adults. There has been little research on the effects of footwear on running biomechanics in youth. HYPOTHESIS: Running biomechanics of youth will be significantly affected by changes in footwear. Minimal shoe running will demonstrate similarities to barefoot. STUDY DESIGN: Crossover study design: randomized trial. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 14 active male youth (8-12 years old) participants with no previous exposure to minimalist shoes or barefoot running had running biomechanics (lower extremity sagittal plane kinematics and vertical ground reaction forces [vGRFs]) collected and analyzed in 3 footwear conditions (barefoot, traditional, and minimal shoe). RESULTS: The average vertical loading rate (AVLR) was significantly greater running barefoot (173.86 bodyweights per second [BW/s]) and in the minimal shoe (138.71 BW/s) compared with the traditional shoe (78.06 BW/s), (P < 0.01). There were significant differences between shoe conditions for knee flexion at initial contact (P < 0.01), knee sagittal plane excursion (P < 0.01), peak dorsiflexion (P < 0.01), and dorsiflexion at initial contact (P = 0.03). No participants displayed a forefoot-strike during this study. CONCLUSION: The introduction of barefoot and minimalist running in habitually shod youth significantly affected the running biomechanics of youth and caused immediate alterations in both lower extremity kinematics and vGRFs. Running barefoot or in minimal shoes dramatically increased the AVLR, which has been associated with injury, compared with a traditional shoe. CLINICAL RELEVANCE: This study evaluated the effects of footwear on overground running biomechanics, including AVLR, in pre- and early-adolescent youth males. Based on our findings, clinicians should exercise caution in barefoot or minimal shoe transition among young, habitually shod, runners due to the immediate and dramatic increases in AVLRs.

Association Between Markerless Motion Capture Screenings and Musculoskeletal Injury Risk for Military Trainees: A Large Cohort and Reliability Study.

BACKGROUND: Markerless motion capture (MMC) systems used to screen for musculoskeletal injury (MSKI) risk have become popular in military and collegiate athletic settings. However, little is known regarding the test-retest reliability or, more importantly, the ability of these systems to accurately identify individuals at risk for MSKI. PURPOSE: To determine the association between scores from a proprietary MMC movement screen test and the likelihood of suffering a subsequent MSKI and establish the test-retest reliability of the MMC system used. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Trainees for the Air Force Special Warfare program underwent MMC screenings immediately before entering the 8-week training course. MSKI data were extracted from a database for the surveillance period for each trainee. Logistic regression analyses were performed to identify associations between baseline MMC scores and the likelihood of suffering any MSKI or, specifically, a lower extremity MSKI. The test-retest portion of the study collected MMC scores from 10 separate participants performing 4 trials of the standard test procedures. Reliability was assessed using intraclass correlation coefficients by a single rater. RESULTS: Overall, 1570 trainees, of whom 800 (51%) suffered an MSKI, were included in the analysis. MMC scores poorly predicted the likelihood of any or a lower extremity MSKI (odds ratio, 1.01-1.02). Further, receiver operating characteristic curve analyses demonstrated poor sensitivity and specificity for prediction of MSKI with MMC scores (area under the curve = 0.53). Finally, intraclass correlation coefficients from the test-retest analysis of MMC scores ranged from 0.157 to 0.602. CONCLUSION: This MMC system displayed poor to moderate test-retest reliability and did not demonstrate the ability to discriminate between individuals who were and were not likely to suffer an MSKI.

Association of Jump-Landing Biomechanics With Tibiofemoral Articular Cartilage Composition 12 Months After ACL Reconstruction.

BACKGROUND: Excessively high joint loading during dynamic movements may negatively influence articular cartilage health and contribute to the development of posttraumatic osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Little is known regarding the link between aberrant jump-landing biomechanics and articular cartilage health after ACLR. PURPOSE/HYPOTHESIS: The purpose of this study was to determine the associations between jump-landing biomechanics and tibiofemoral articular cartilage composition measured using T1ρ magnetic resonance imaging (MRI) relaxation times 12 months postoperatively. We hypothesized that individuals who demonstrate alterations in jump-landing biomechanics, commonly observed after ACLR, would have longer T1ρ MRI relaxation times (longer T1ρ relaxation times associated with less proteoglycan density). STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 27 individuals with unilateral ACLR participated in this cross-sectional study. Jump-landing biomechanics (peak vertical ground-reaction force [vGRF], peak internal knee extension moment [KEM], peak internal knee adduction moment [KAM]) and T1ρ MRI were collected 12 months postoperatively. Mean T1ρ relaxation times for the entire weightbearing medial femoral condyle, lateral femoral condyle (global LFC), medial tibial condyle, and lateral tibial condyle (global LTC) were calculated bilaterally. Global regions of interest were further subsectioned into posterior, central, and anterior regions of interest. All T1ρ relaxation times in the ACLR limb were normalized to the uninjured contralateral limb. Linear regressions were used to determine associations between T1ρ relaxation times and biomechanics after accounting for meniscal/chondral injury. RESULTS: Lower ACLR limb KEM was associated with longer T1ρ relaxation times for the global LTC (ΔR 2 = 0.24; P = .02), posterior LTC (ΔR 2 = 0.21; P = .03), and anterior LTC (ΔR 2 = 0.18; P = .04). Greater ACLR limb peak vGRF was associated with longer T1ρ relaxation times for the global LFC (ΔR 2 = 0.20; P = .02) and central LFC (ΔR 2 = 0.15; P = .05). Peak KAM was not associated with T1ρ outcomes. CONCLUSION: At 12 months postoperatively, lower peak KEM and greater peak vGRF during jump landing were related to longer T1ρ relaxation times, suggesting worse articular cartilage composition.

Running Biomechanics Before Injury and 1 Year After Anterior Cruciate Ligament Reconstruction in Division I Collegiate Athletes.

BACKGROUND: Preinjury running biomechanics are an ideal comparator for quantifying recovery after anterior cruciate ligament (ACL) reconstruction (ACLR), allowing for assessments within the surgical and nonsurgical limbs. However, availability of preinjury running biomechanics is rare and has been reported in case studies only. PURPOSE/HYPOTHESIS: The purpose of this study was to determine if running biomechanics return to preinjury levels within the first year after ACLR among collegiate athletes. We hypothesized that (1) surgical knee biomechanics would be significantly reduced shortly after ACLR and would not return to preinjury levels by 12 months and (2) nonsurgical limb mechanics would change significantly from preinjury. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Thirteen Division I collegiate athletes were identified between 2015 and 2020 (6 female; mean ± SD age, 20.7 ± 1.3 years old) who had whole body kinematics and ground-reaction forces recorded during treadmill running (3.7 ± 0.6 m/s) before sustaining an ACL injury. Running analyses were repeated at 4, 6, 8, and 12 months (4M, 6M, 8M, 12M) after ACLR. Linear mixed effects models were used to assess differences in running biomechanics between post-ACLR time points and preinjury within each limb, reported as Tukey-adjusted P values. RESULTS: When compared with preinjury, the surgical limb displayed significant deficits at all postoperative assessments (P values <.01; values reported as least squares mean difference [SE]): peak knee flexion angle (4M, 13.2° [1.4°]; 6M, 9.9° [1.4°]; 8M, 9.8° [1.4°]; 12M, 9.0° [1.5°]), peak knee extensor moment (N·m/kg; 4M, 1.32 [0.13]; 6M, 1.04 [0.13]; 8M, 1.04 [0.13]; 12M, 0.87 [0.15]; 38%-57% deficit), and rate of knee extensor moment (N·m/kg/s; 4M, 22.7 [2.4]; 6M, 17.9 [2.3]; 8M, 17.5 [2.4]; 12M, 16.1 [2.6]; 33%-46% deficit). No changes for these variables from preinjury (P values >.88) were identified in the nonsurgical limb. CONCLUSION: After ACLR, surgical limb knee running biomechanics were not restored to the preinjury state by 12M, while nonsurgical limb mechanics remained unchanged as compared with preinjury. Collegiate athletes after ACLR demonstrate substantial deficits in running mechanics as compared with preinjury that persist beyond the typical return-to-sport time frame. The nonsurgical knee appears to be a valid reference for recovery of the surgical knee mechanics during running, owing to the lack of change within the nonsurgical limb.

The Relationship Between Pitching Mechanics and Injury: A Review of Current Concepts.

CONTEXT: The overhand pitch is one of the fastest known human motions and places enormous forces and torques on the upper extremity. Shoulder and elbow pain and injury are common in high-level pitchers. A large body of research has been conducted to understand the pitching motion. EVIDENCE ACQUISITION: A comprehensive review of the literature was performed to gain a full understanding of all currently available biomechanical and clinical evidence surrounding pitching motion analysis. These motion analysis studies use video motion analysis, electromyography, electromagnetic sensors, and markered motion analysis. This review includes studies performed between 1983 and 2016. STUDY DESIGN: Clinical review. LEVEL OF EVIDENCE: Level 5. RESULTS: The pitching motion is a kinetic chain, in which the force generated by the large muscles of the lower extremity and trunk during the wind-up and stride phases are transferred to the ball through the shoulder and elbow during the cocking and acceleration phases. Numerous kinematic factors have been identified that increase shoulder and elbow torques, which are linked to increased risk for injury. CONCLUSION: Altered knee flexion at ball release, early trunk rotation, loss of shoulder rotational range of motion, increased elbow flexion at ball release, high pitch velocity, and increased pitcher fatigue may increase shoulder and elbow torques and risk for injury.

Effects of Rotator Cuff Pathology and Physical Therapy on In Vivo Shoulder Motion and Clinical Outcomes in Patients With a Symptomatic Full-Thickness Rotator Cuff Tear.

BACKGROUND: Physical therapy (PT) is often prescribed for patients with rotator cuff tears. The extent to which PT influences strength, range of motion (ROM), and patient-reported outcomes has been studied extensively, but the effect of PT on in vivo joint kinematics is not well understood. PURPOSE: To assess the influence of symptomatic rotator cuff pathology and the effects of PT on shoulder motion, strength, and patient-reported outcomes. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty-five patients with a symptomatic rotator cuff tear and 25 age-matched asymptomatic control subjects were recruited. Shoulder motion was measured using a biplane radiography imaging system, strength was assessed with a Biodex dynamometer, and patient-reported outcomes were assessed using the Western Ontario Rotator Cuff Index and visual analog scale (VAS) pain scores. Data were acquired from the patients before and after 8 weeks of physical therapy. Data were acquired at 1 time point for the control subjects. RESULTS: Compared with the control subjects, patients with a symptomatic rotator cuff tear had significantly worse pain/function scores (P < .01); less ROM (P < .01); lower abduction (ABD), external rotation (ER), and internal rotation (IR) strength (P < .01); less scapulothoracic posterior tilt (P = .05); and lower glenohumeral joint elevation (P < .01). Physical therapy resulted in improved pain/function scores (P < .01), increased ROM (P < .02), increased scapulothoracic posterior tilt (P = .05), increased glenohumeral joint elevation (P = .01), and decreased acromiohumeral distance (AHD) (P = .02). CONCLUSION: Compared with age-matched controls, patients had worse pain/function scores, less ROM, and lower ABD, ER, and IR strength. Patients also had less scapulothoracic anteroposterior tilt, less glenohumeral joint elevation, and an altered glenohumeral joint contact path. PT resulted in improved pain/function scores, increased ROM, greater posterior scapulothoracic tilt, increased glenohumeral joint elevation, an increased range of superoinferior joint contact, and a lower mean AHD. Of these differences, PT only returned scapulothoracic tilt to control levels. CLINICAL RELEVANCE: This study documents the effects of PT on shoulder motion and conventional clinical outcomes. It is expected that understanding how changes in joint motion are associated with conventional clinical outcomes will lead to improved nonoperative interventions for patients with rotator cuff tears.

Kinematics of Shooting in High School and Collegiate Lacrosse Players With and Without Low Back Pain.

BACKGROUND: Low back pain (LBP) and motion alterations can occur in athletes who engage in high-speed throwing motions. The relationship between LBP and shooting motion in lacrosse players is not yet known. PURPOSE: To quantify the effects of LBP on key kinematic parameters of the lacrosse shot and determine the contribution of the severity of LBP on specific kinematic parameters of the shooting motion. STUDY DESIGN: Controlled laboratory study. METHODS: High school and collegiate players (N = 24) were stratified into 2 groups based on back pain symptoms (LBP or no pain). Three-dimensional motion capture of overhead throws was used to collect data on knee, pelvis, trunk, and shoulder kinematics as well as crosse stick (the stick capped with a strung net) and ball speed. RESULTS: Mean low back numeric pain rating scale (NRSpain) score was 2.9. Knee flexion at ball release was greater in the LBP than no pain group, indicating a more bent knee (P = .04). The LBP group demonstrated less angular velocity transfer from pelvis to trunk than the no pain group (P = .05). Total range of motion of the pelvis and shoulders during the shot and follow-through were less in the LBP group than the no pain group (83.6° ± 24.5° vs 75.9° ± 24.5°, P = .05). Age- and sex-adjusted regression analyses revealed that the low back NRSpain rating contributed 6.3% to 25.0% of the variance to the models of shoulder transverse rotation range of motion, trunk and shoulder rotation angular velocities, and knee flexion angle (P < .05). CONCLUSION: LBP severity significantly contributes to trunk and shoulder motion restriction during lacrosse shooting. Inclusion of lumbopelvic and core training and prehabilitation programs for high school and collegiate players may reduce pain in affected players as well as help them to attain appropriate motion parameters and avoid secondary musculoskeletal injuries. CLINICAL RELEVANCE: This research identified a prehabilitation need in the understudied lacrosse population. Therapeutic strategies can be developed to strengthen the throwing motion, which could control mechanical loading patterns on the low back and minimize pain symptoms in players with chronic LBP.

Lower extremity biomechanical relationships with different speeds in traditional, minimalist, and barefoot footwear.

Minimalist running footwear has grown increasingly popular. Prior studies that have compared lower extremity biomechanics in minimalist running to traditional running conditions are largely limited to a single running velocity. This study compares the effects of running at various speeds on foot strike pattern, stride length, knee angles and ankle angles in traditional, barefoot, and minimalist running conditions. Twenty-six recreational runners (19-46 years of age) ran on a treadmill at a range of speeds (2.5-4.0 m·sec(-1)). Subjects ran with four different footwear conditions: personal, standard, and minimalist shoes and barefoot. 3D coordinates from video data were collected. The relationships between speed, knee and ankle angles at foot strike and toe-off, relative step length, and footwear conditions were evaluated by ANCOVA, with speed as the co-variate. Distribution of non-rearfoot strike was compared across shod conditions with paired t-tests. Non-rearfoot strike distribution was not significantly affected by speed, but was different between shod conditions (p < 0.05). Footwear condition and speed significantly affected ankle angle at touchdown, independent of one another (F [3,71] = 10.28, p < 0.001), with barefoot and minimalist running exhibiting greater plantarflexion at foot strike. When controlling for foot strike style, barefoot and minimalist runners exhibited greater plantarflexion than other conditions (p < 0.05). Ankle angle at lift-off and relative step length exhibited a significant interaction between speed and shod condition. Knee angles had a significant relationship with speed, but not with footwear. There is a clear influence of footwear, but not speed, on foot strike pattern. Additionally, speed and footwear predict ankle angles (greater plantarflexion at foot strike) and may have implications for minimalist runners and their risk of injury. Long-term studies utilizing various speeds and habituation times are needed. Key pointsFoot strike style does not change with speed, but does change with shod condition, with minimalist shoes exhibiting an intermediate distribution of forefoot strikes between barefoot and traditional shoes.Plantarflexion at touchdown does change with speed and with shoe type, with barefoot and minimalist shoes exhibiting a greater plantarflexion angle than traditional running shoes.Knee angles change with speed in all shod conditions, but knee flexion at touchdown is not different between shod conditions.Relative step length changes with speed and shod condition, but there is an interaction between these variables such that step length increases more quickly in traditional shoes as speed increases.

Postoperative restoration of upper extremity motion and neuromuscular control during the overhand pitch: evaluation of tenodesis and repair for superior labral anterior-posterior tears.

BACKGROUND: Superior labral anterior-posterior (SLAP) tears are a common cause of shoulder pain and dysfunction in overhand throwers. Treatment outcomes remain unpredictable, with a large percentage of athletes unable to return to sport. There is considerable debate about the optimal treatment between debridement, repair, and tenodesis. HYPOTHESIS: Labral repair more closely restores neuromuscular control and motion during the overhand pitch than tenodesis of the long head of the biceps. STUDY DESIGN: Controlled laboratory study. METHODS: Eighteen pitchers, including 7 uninjured controls, 6 players pitching after SLAP repair, and 5 players pitching after subpectoral biceps tenodesis (BT), underwent simultaneous surface electromyographic measurement at 1500 Hz and motion analysis at 120 Hz with a 14-camera markerless motion analysis system and high-speed video (120 Hz) to confirm accurate motion tracking. Patients had undergone surgery at least 1 year previously and had returned to pitching with a painless shoulder. RESULTS: No significant differences were observed in the long head of the biceps muscle, short head of the biceps muscle, deltoid, infraspinatus, or latissimus activity between controls, patients after SLAP repair, and patients after BT. The variability from pitch to pitch for each study participant was similar between groups. Based on visual inspection of the activity time plots, BT appeared to more closely restore the normal pattern of muscular activation within the long head of the biceps muscle than did SLAP repair. There were no significant differences between controls and postoperative patients in the majority of pitching kinematics; however, pitchers after SLAP repair showed significantly altered patterns of thoracic rotation (P = .034) compared with controls and were significantly less likely to fall into previously published normal values for lead knee flexion at front foot contact (P = .019). CONCLUSION: While both BT and SLAP repair can restore physiologic neuromuscular control, pitchers who undergo SLAP repair may exhibit altered patterns of thoracic rotation when compared with controls and pitchers who undergo BT. CLINICAL RELEVANCE: While both tenodesis and SLAP repair can restore physiologic neuromuscular control, SLAP repair may alter pitching biomechanics.