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Background: The relationship between self-reported symptoms and the severity of patellar tendon abnormality (PTA) as seen on magnetic resonance imaging and ultrasound is unclear, but biomechanical testing may resolve this. Purpose: To (1) compare land-jump limb biomechanics between pre- and postseason timepoints, (2) assess whether seasonal changes in biomechanics are associated with seasonal changes in PTA and symptom severity, and (3) explore models that identify seasonal changes in PTA and symptoms with seasonal changes in biomechanics in collegiate basketball players. Study Design: Cohort study; Level of evidence, 2. Methods: Victorian Institute of Sport Assessment Scale – Patellar Tendon (VISA-P) scores and bilateral measurements from 18 National Collegiate Athletic Association Division I and II male basketball players (n = 36 limbs) at the preseason (visit 1) and postseason (visit 2) timepoints were collected. PTA was graded with ultrasound and magnetic resonance imaging morphology measurements proximally and distally, and 3-dimensional lower extremity sagittal kinematics and kinetics were measured during a land-jump test. Multivariate and chi-square analyses assessed timepoint differences. The association of seasonal (Δ = visit 2 - visit 1) biomechanics with seasonal morphology (ΔPTA: no change/worsened) and symptoms (ΔVISA-P: improved/no change/worsened) was tested with multivariate models. Logistic regressions modeled the accuracy of seasonal biomechanics to classify seasonal PTA and symptoms. Results: Three athletes (6 limbs) at visit 1 and 2 athletes (4 limbs) at visit 2 were symptomatic. VISA-P scores were not significantly different between preseason and postseason. Regarding PTA, multivariate analyses found differences among grouped ground-reaction force variables (P <.05); univariate analyses found that worsened PTA was associated with seasonal decreases in peak vertical jumping force and with seasonal increases in knee flexion velocity at contact and maximum knee flexion velocity (P <.05 for all). Regarding VISA-P scores, multivariate analyses found differences among grouped hip (P <.01) and ankle (P <.05) kinematic variables; univariate analyses found that worsened VISA-P was associated with seasonal increases in hip (P <.01) and knee (P <.01) flexion velocity at contact and seasonal increases in ankle range of motion (P <.05). Conclusion: The findings demonstrated an association between seasonal changes in dynamic lower extremity biomechanics and seasonal changes in patellar tendon imaging signals as well as self-reported symptoms. [ABSTRACT FROM AUTHOR]

Background: Patellar tendinopathy is a degenerative condition that predominantly affects jumping athletes. Symptoms may be subtle or nonexistent at preseason, but structural abnormalities may be present. Assessing patellar tendon abnormality (PTA) through magnetic resonance imaging (MRI) and ultrasound (US) and classifying symptoms using the Victorian Institute for Sport Assessment–Patellar tendon (VISA-P) may provide useful insights if combined with biomechanics measurements. Purpose: To (1) assess whether land-jump biomechanical patterns are associated with clinically pertinent PTA as seen on imaging and through VISA-P scores and (2) model the contributing risk and accuracy of biomechanics to classify PTA and symptomatic observations. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 26 National Collegiate Athletic Association Division I and II male basketball players (n = 52 limbs) were recruited during the preseason. We collected VISA-P scores, bilateral PTA through US and MRI morphology measurements, and bilateral 3-dimensional lower extremity kinematics and kinetics measurements from a land-jump test from an 18-inch-high (45.7-cm-high) box. Statistically, each limb was treated independently. The association of biomechanics with PTA and symptoms (VISA-P score <80) was tested with multivariate models and post hoc tests. Logistic regression modeled relative risk and accuracy of biomechanical variables to classify PTA and symptomatic limbs. Results: There were 19 to 24 limbs with PTA depending on US and MRI measurements. Differences in hip and knee kinematic strategies and ground-reaction loads were associated with PTA and symptomatic limbs. Peak landing vertical ground-reaction force was significantly decreased (169 ± 26 vs 195 ± 29 %body weight; P = .001), and maximum hip flexion velocity was significantly increased (416 ± 74 vs 343 ± 94 deg/s; P = .005) in limbs with versus without PTA on imaging. Knee flexion at the initial contact was decreased in symptomatic versus healthy limbs (17°± 5° vs 21°± 5°, respectively; P = .045). Regression models classified PTA limbs and symptomatic limbs with 71.2% to 86.5% accuracy. Hip and knee maximum flexion velocity and vertical ground-reaction force variables were most common across models observing clinically pertinent PTA. Conclusion: Our findings suggested that functional kinematic and kinetic biomechanical strategies at the hip and knee were associated with PTA, identified on imaging, and symptomatic limbs. [ABSTRACT FROM AUTHOR]

Increased joint stress and malalignment are etiologic factors in osteoarthritis. Static tibiofemoral frontal plane malalignment is associated with patellofemoral osteoarthritis (PFOA). Patellofemoral joint stress is increased by activities such as sit-to-stand (STS); this stress may be even greater if dynamic frontal plane tibiofemoral malalignment occurs. If hip muscle or quadriceps weakness is present in persons with PFOA, aberrant tibiofemoral frontal plane movement may occur, with increased patellofemoral stress. No studies have investigated frontal plane tibiofemoral and hip kinematics during STS in persons with PFOA or the relationship of hip muscle and quadriceps strength to these motions. Eight PFOA and seven control subjects performed STS from a stool during three-dimensional motion capture. Hip muscle and quadriceps strength were measured as peak isometric force. The PFOA group demonstrated increased peak tibial abduction angles during STS, and decreased hip abductor, hip extensor, and quadriceps peak force versus controls. A moderate inverse relationship between peak tibial abduction angle and peak hip abductor force was present. No difference between groups was found for peak hip adduction angle or peak hip external rotator force. Dynamic tibiofemoral malalignment and proximal lower extremity weakness may cause increased patellofemoral stress and may contribute to PFOA incidence or progression. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the magnitude of knee kinematic coupling between genders and among open- and closed-chain tasks. A secondary purpose was to compare the consistency of knee kinematic coupling between genders and among open- and closed-chain tasks. Vector-coding methods were used to quantify coupling in the sagittal and transverse planes of the knee between full extension and 20 degrees of flexion as 10 males and 10 females walked, ascended and descended stairs, and performed a passive pendulum leg drop. An ANOVA showed no main effect of gender. There was a main effect of task, where coupling during the stance phase of walking was significantly greater than each of the other tasks. Intraclass correlation values suggested that males were slightly more consistent than females. A general lack of divergence between genders may be related to the tasks analyzed in this study. It is possible that more strenuous tasks may elicit larger differences. [ABSTRACT FROM AUTHOR]

Background: Few studies have investigated detailed 3-dimensional lower extremity kinematics during baseball pitching in adolescent athletes during extended play. Changes in these parameters may affect performance outcomes. Purpose: To investigate whether adolescent baseball pitchers experience changes in lower extremity kinematics and event timing during a simulated game-length pitching bout. Study Design: Descriptive laboratory study. Methods: Twelve male adolescent pitchers (aged 14-16 years) threw 6 sets of 15 fastball pitches from an artificial pitching mound to a target at regulation distance. Joint angles and angular velocities at the hip, knee, and ankle of both legs were collected throughout the phases of the pitching cycle as well as stride length, pelvis orientation, pitch duration, timing of foot contact and ball release, ball speed, and pitching accuracy. Paired t tests (P < .05) were used to compare the dependent variables between the last 5 pitches of the second (baseline) and sixth (final) sets. Results: During the stride phase, decreased maximum angular excursions for hip extension (baseline: 14.7° ± 9.8°; final: 11.6° ± 10.3°; P < .05) and ankle plantar flexion (baseline: 30.2° ± 14.5°; final: 24.2° ± 15.3°; P < .05) as well as maximum angular velocity for knee extension (baseline: 144.9 ± 63.3 deg·s-1; final: 121.7 ± 62.0 deg·s-1; P < .05) were observed between sets in the trailing leg. At foot contact, pitchers had decreased hip flexion (baseline: 69.5° ± 10.1°; final: 66.5° ± 11.8°; P < .05) and increased hip abduction (baseline: 20.7° ± 8.9°; final: 25.4° ± 6.0°; P < .05) in the leading leg in the final set. Compared with the baseline set, ball speed significantly decreased in the final set (29.5 ± 2.5 m·s-1 vs 28.3 ± 2.5 m·s-1, respectively; P < .05). Conclusion: Kinematic changes and decreased ball speeds observed in the final set suggest that adolescent pitchers are unable to maintain lower extremity kinematics and performance as a result of extended play. Clinical Relevance: The results from this study may warrant further investigation into how altered lower extremity kinematics may affect trunk and upper extremity function, performance, and risk of injuries during pitching in adolescent athletes, particularly during actual game play. [ABSTRACT FROM AUTHOR]

Alterations in joint mechanics have been associated with common overuse injuries. An increase in running cadence in healthy runners has been shown to improve several parameters that have been tied to injury, but the reorganisation of motion that produces these changes has not been examined. The purpose of this study was to determine if runners change their segment coordination and coordination variability with an acute increase in cadence. Data were collected as ten uninjured runners ran overground at their preferred cadence as well as a cadence 10% higher than preferred. Segment coordination and coordination variability were calculated for select thigh-shank and shank-foot couples and selected knee mechanics were also calculated. Paired t-tests were used to examine differences between the preferred and increased cadence conditions. With increased cadence, there was a decrease in peak knee flexion and a later occurrence of peak knee flexion and internal rotation and shank internal rotation. Segment coordination was altered with most changes occurring in mid-late stance. Coordination variability decreased with an increase in cadence across all couples and phases of gait. These results suggest examination of coordination and its variability could give insight into the risk of intervention-induced injury. [ABSTRACT FROM AUTHOR]

Many studies have documented the association between mechanical deviations from normal and the presence or risk of injury. Some runners attempt to change mechanics by increasing running cadence. Previous work documented that increasing running cadence reduces deviations in mechanics tied to injury. The long-term effect of a cadence retraining intervention on running mechanics and energy expenditure is unknown. This study aimed to determine if increasing running cadence by 10% decreases running efficiency and changes kinematics and kinetics to make them less similar to those associated with injury. Additionally, this study aimed to determine if, after 6 weeks of cadence retraining, there would be carryover in kinematic and kinetic changes from an increased cadence state to a runner’s preferred running cadence without decreased running efficiency. We measured oxygen uptake, kinematic and kinetic data on six uninjured participants before and after a 6-week intervention. Increasing cadence did not result in decreased running efficiency but did result in decreases in stride length, hip adduction angle and hip abductor moment. Carryover was observed in runners’ post-intervention preferred running form as decreased hip adduction angle and vertical loading rate. [ABSTRACT FROM AUTHOR]

BACKGROUND: Patellofemoral osteoarthritis (PFOA) is associated with pain and decreased self-reported function. The impact of PFOA on actual physical performance is currently unknown. OBJECTIVE: To investigate the impact of PFOA on physical performance and pain. METHODS: Eight participants aged 40-65 years with bilateral, symptomatic, radiographic PFOA and 7 age- and gender-matched pain-free control participants without radiographic PFOA were studied. Physical performance was measured with the Timed-Up-and-Go (TUG) and 50-foot Fast-Paced-Walk (FPW) tests. Dependent variables included time to complete the TUG and FPW; pretest-posttest change in pain intensity (TUG and FPW); and self-reports of perceived knee pain, stiffness, and physical function. Data were analyzed with nonparametric statistics. RESULTS: The PFOA group TUG time was longer than the control group (p=0.01). No difference between groups was found for FPW time. Pretest-posttest pain increased for the TUG and FPW in PFOA participants (p< 0.05). The PFOA group reported greater knee pain, stiffness, and less physical function than controls (previous 48 hours) (p < 0.01). CONCLUSIONS: Symptomatic, radiographic PFOA is associated with increased pain during the TUG and FPW tests and longer time required to complete the TUG. The TUG may be a more sensitive test of physical performance in PFOA. [ABSTRACT FROM AUTHOR]

Objective. Abnormal foot posture and function have been proposed as possible risk factors for low back pain, but this has not been examined in detail. The objective of this study was to explore the associations of foot posture and foot function with low back pain in 1930 members of the Framingham Study (2002–05).Methods. Low back pain, aching or stiffness on most days was documented on a body chart. Foot posture was categorized as normal, planus or cavus using static weight-bearing measurements of the arch index. Foot function was categorized as normal, pronated or supinated using the centre of pressure excursion index derived from dynamic foot pressure measurements. Sex-specific multivariate logistic regression models were used to examine the associations of foot posture, foot function and asymmetry with low back pain, adjusting for confounding variables.Results. Foot posture showed no association with low back pain. However, pronated foot function was associated with low back pain in women [odds ratio (OR) = 1.51, 95% CI 1.1, 2.07, P = 0.011] and this remained significant after adjusting for age, weight, smoking and depressive symptoms (OR = 1.48, 95% CI 1.07, 2.05, P = 0.018).Conclusion. These findings suggest that pronated foot function may contribute to low back symptoms in women. Interventions that modify foot function, such as orthoses, may therefore have a role in the prevention and treatment of low back pain. [ABSTRACT FROM PUBLISHER]

The article presents a study which aims to determine whether there are changes in foot structure that persist after pregnancy. The authors mention that the result showed a significant decrease in arch height and arch rigidity index with concomitant increases in foot length and arch drop. They conclude that the changes in the feet could potentially contribute to the increased risk for subsequent musculoskeletal disorders in women.