Richard B. Souza

Differences in Hip Kinematics, Muscle Strength, and Muscle Activation Between Subjects With and Without Patellofemoral Pain

STUDY DESIGN Controlled laboratory study using a cross-sectional design. OBJECTIVES To determine whether females with patellofemoral pain (PFP) demonstrate differences in hip kinematics, hip muscle strength, and hip muscle activation patterns when compared to pain-free controls. BACKGROUND It has been proposed that abnormal hip kinematics may contribute to the development of PFP. However, research linking hip function to PFP remains limited. METHODS AND MEASURES Twenty-one females with PFP and 20 pain-free controls participated in this study. Hip kinematics and activity level of hip musculature were obtained during running, a drop jump, and a step-down maneuver. Isometric hip muscle torque production was quantified using a multimodal dynamometer. Group differences were assessed across tasks using mixed-design 2-way analyses of variance and independent t tests. RESULTS When averaged across all 3 activities, females with PFP demonstrated greater peak hip internal rotation compared to the control group (mean +/- SD, 7.6 degrees +/- 7.0 degrees versus 1.2 degrees +/- 3.8 degrees; P<.05). The individuals in the PFP group also exhibited diminished hip torque production compared to the control group (14% less hip abductor strength and 17% less hip extensor strength). Significantly greater gluteus maximus recruitment was observed for individuals in the PFP group during running and the step-down task. CONCLUSION The increased peak hip internal rotation motion observed for females in the PFP group was accompanied by decreased hip muscle strength. The increased activation of the gluteus maximus in individuals with PFP suggests that these subjects were attempting to recruit a weakened muscle, perhaps in an effort to stabilize the hip joint. Our results support the proposed link between abnormal hip function and PFP.

Predictors of Hip Internal Rotation During Running An Evaluation of Hip Strength and Femoral Structure in Women With and Without Patellofemoral Pain

Background Recent studies have suggested that excessive hip internal rotation during dynamic tasks may be associated with patellofemoral pain. Although diminished hip-muscle strength and altered femoral morphologic characteristics have been implicated in abnormal hip rotation in persons with patellofemoral pain, no study has confirmed this hypothesis. Hypothesis Women with patellofemoral pain would demonstrate increased average hip internal rotation, decreased hip-muscle performance, and abnormal femoral shape compared with controls. Furthermore, measures of hip strength and femoral shape are predictive of average hip internal rotation during running. Study Design Cross-sectional study; Level of evidence, 3. Methods Nineteen women with patellofemoral pain and 19 pain-free controls participated. Lower extremity kinematics during running, hip-muscle performance, and femoral morphologic characteristics on magnetic resonance imaging were quantified. Independent t tests were used to assess group differences. Stepwise linear regression was used to determine whether measures of strength and/or structure were predictive of average hip internal rotation during running. Results Participants with patellofemoral pain demonstrated significantly greater average hip internal rotation (8.2° ± 6.6° vs 0.3° ± 3.6°; P <. 001), reduced hip-muscle strength in 8 of 10 hip strength measurements, and greater femoral inclination (132.8° ± 5.2° vs 128.4° ± 5.0°; P =. 011) compared with controls. Stepwise regression revealed that isotonic hip extension endurance was the only predictor of average hip internal rotation (r = −.451; P =. 004). Conclusion Abnormal hip kinematics in women with patellofemoral pain appears to be the result of diminished hip-muscle performance as opposed to altered femoral structure. The results suggest that assessment of hip-muscle performance should be considered in the evaluation and treatment of patellofemoral joint dysfunction.

Femur Rotation and Patellofemoral Joint Kinematics: A Weight-Bearing Magnetic Resonance Imaging Analysis

STUDY DESIGN Controlled laboratory study using a cross-sectional design. OBJECTIVES To compare patellofemoral joint kinematics, femoral rotation, and patella rotation between females with patellofemoral pain (PFP) and pain-free controls using weight-bearing kinematic magnetic resonance imaging. BACKGROUND Recently, it has been recognized that patellofemoral malalignment may be the result of femoral motion as opposed to patella motion. METHODS Fifteen females with PFP and 15 pain-free females between the ages of 18 and 45 years participated in this study. Kinematic imaging of the patellofemoral joint was performed using a vertically open magnetic resonance imaging system. Axial-oblique images were obtained using a fast gradient-echo pulse sequence. Images were acquired at a rate of 1 image per second while subjects performed a single-limb squat. Measures of femur and patella rotation (relative to the image field of view), lateral patella tilt, and lateral patella displacement were made from images obtained at 45 degrees , 30 degrees , 15 degrees , and 0 degrees of knee flexion. Group differences were assessed using a mixed-model analysis of variance with repeated measures. RESULTS When compared to the control group, females with PFP demonstrated significantly greater lateral patella displacement at all angles evaluated and significantly greater lateral patella tilt at 30 degrees , 15 degrees , and 0 degrees of knee flexion. Similarly, greater medial femoral rotation was observed in the PFP group at 45 degrees , 15 degrees , and 0 degrees of knee flexion when compared to the control group. No group differences in patella rotation were found. CONCLUSION Altered patellofemoral joint kinematics in females with PFP appears to be related to excessive medial femoral rotation, as opposed to lateral patella rotation. Our results suggest that the control of femur rotation may be important in restoring normal patellofemoral joint kinematics. J Orthop Sports Phys Ther 2010;40(5):277-285, Epub 12 March 2010. doi:10.2519/jospt.2010.3215.

Cartilage and meniscus assessment using T1rho and T2 measurements in healthy subjects and patients with osteoarthritis.

OBJECTIVE The purpose of this study was to evaluate meniscal degeneration in healthy subjects and subjects with osteoarthritis (OA) using T(1ρ) and T(2) measurements and to examine the interrelationship between cartilage and meniscus abnormalities. METHODS Quantitative assessment of cartilage and meniscus was performed using 3T Magnetic Resonance Imaging (MRI) with a T(1ρ) and T(2) mapping technique in 19 controls and 44 OA patients. A sagittal T(2)-weighted fast spin echo (FSE) fat-saturated image was acquired for cartilage and meniscal Whole-Organ Magnetic Resonance Imaging Score (WORMS) assessment. Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores were obtained to assess clinical symptoms. RESULTS The posterior horn of the medial meniscus (PHMED) had the highest incidence of degeneration. Stratifying subjects on the basis of PHMED grade revealed that the T(1ρ) and the T(2) measurements of the PHMED and the medial tibial (MT) cartilage were higher in subjects having a meniscal tear (meniscal grade 2-4) compared to subjects with a meniscal grade of 0 or 1 (P<0.05). While not statistically significant, there was a trend for T(1ρ) and T(2) being higher in PHMED grade 1 compared to grade 0 (P=0.094, P=0.073 respectively). WOMAC scores had a stronger correlation with meniscus relaxation measures than cartilage measures. CONCLUSIONS Magnetic Resonance (MR) T(1ρ) and T(2) measurements provide a non-invasive means of detecting and quantifying the severity of meniscal degeneration. Meniscal damage has been implicated in OA progression and is correlated with cartilage degeneration. Early detection of meniscal damage represented by elevations in meniscal relaxation measures may identify subjects at increased risk for OA.

Trunk Position Influences the Kinematics, Kinetics, and Muscle Activity of the Lead Lower Extremity During the Forward Lunge Exercise

STUDY DESIGN Experimental laboratory study. OBJECTIVES To examine how a change in trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. BACKGROUND Altering the position of the trunk during the forward lunge exercise is thought to affect the muscular actions of the lead lower extremity. However, no studies have compared the biomechanical differences between the traditional forward lunge and its variations. METHODS AND MEASURES Ten healthy adults (5 males, 5 females; mean age +/- SD, 26.7 +/- 3.2 years) participated. Lower extremity kinematics, kinetics, and surface electromyographic (EMG) data were obtained while subjects performed 3 lunge exercises: normal lunge with the trunk erect (NL), lunge with the trunk forward (LTF), and lunge with trunk extension (LTE). A 1-way analysis of variance with repeated measures was used to compare lower extremity kinematics, joint impulse (area under the moment-time curve), and normalized EMG (highest 1-second window of activity for selected lower extremity muscles) among the 3 lunge conditions. RESULTS During the LTF condition, significant increases were noted in peak hip flexion angle, hip extensor and ankle plantar flexor impulse, as well as gluteus maximus and biceps femoris EMG (P<.015) when compared to the NL condition. During the LTE condition, a significant increase was noted in peak ankle dorsiflexion and a significant decrease was noted in peak hip flexion angle (P<.015) compared to the NL condition. CONCLUSIONS Performing a lunge with the trunk forward increased the hip extensor impulse and the recruitment of the hip extensors. In contrast, performing a forward lunge with the trunk extended did not alter joint impulse or activation of the lower extremity musculature. LEVEL OF EVIDENCE Therapy, level 5.

The tissue diagnostic instrument

Tissue mechanical properties reflect extracellular matrix composition and organization, and as such, their changes can be a signature of disease. Examples of such diseases include intervertebral disk degeneration, cancer, atherosclerosis, osteoarthritis, osteoporosis, and tooth decay. Here we introduce the tissue diagnostic instrument (TDI), a device designed to probe the mechanical properties of normal and diseased soft and hard tissues not only in the laboratory but also in patients. The TDI can distinguish between the nucleus and the annulus of spinal disks, between young and degenerated cartilage, and between normal and cancerous mammary glands. It can quantify the elastic modulus and hardness of the wet dentin left in a cavity after excavation. It can perform an indentation test of bone tissue, quantifying the indentation depth increase and other mechanical parameters. With local anesthesia and disposable, sterile, probe assemblies, there has been neither pain nor complications in tests on patients. We anticipate that this unique device will facilitate research on many tissue systems in living organisms, including plants, leading to new insights into disease mechanisms and methods for their early detection.

The effects of acute loading on T1rho and T2 relaxation times of tibiofemoral articular cartilage.

OBJECTIVE To evaluate the effect of acute loading on healthy and osteoarthritic knee cartilage T(1ρ) and T(2) relaxation times. DESIGN Twenty subjects with radiographic evidence of osteoarthritis (OA) and 10 age-matched controls were enrolled. Magnetic resonance imaging (MRI) acquisition, including T(1ρ) and T(2) map sequences were performed unloaded and loaded at 50% body mass. Cartilage masks were segmented semi-automatically on registered high-resolution spoiled gradient-echo (SPGR) images for each compartment (medial and lateral). Cartilage lesions were identified using a modified Whole Organ Magnetic Resonance Imaging Score (WORMS) score. Statistical differences were explored using separate two-way (group×loading condition) Analysis of Variance (ANOVA) using age as a covariate to evaluate the effects of loading on T(1ρ) and T(2) relaxation times. RESULTS A significant decrease in T(1ρ) (44.5±3.8 vs 40.2±4.8ms for unloaded and loaded, respectively; P<0.001) and T(2) (31.8±3.8 vs 30.5±4.8ms for unloaded and loaded, respectively; P<0.001) relaxation times was observed in the medial compartment with loading while no differences were observed in the lateral compartment. This behavior occurred independent of WORMS score. Cartilage compartments with small focal lesions experienced greater T(1ρ) change scores with loading when compared to cartilage without lesions or cartilage with larger defects (P=0.05). CONCLUSIONS Acute loading resulted in a significant decrease in T(1ρ) and T(2) relaxation times of the medial compartment, with greater change scores observed in cartilage regions with small focal lesions. These data suggest that changes of T(1ρ) values with loading may be related to cartilage biomechanical properties (i.e., tissue elasticity) and may be a valuable tool for the scientist and clinician at identifying early cartilage disease.

Physical activity is associated with magnetic resonance imaging-based knee cartilage T2 measurements in asymptomatic subjects with and those without osteoarthritis risk factors.

OBJECTIVE To evaluate the association of exercise and knee-bending activities with magnetic resonance imaging (MRI)-based knee cartilage T2 relaxation times and morphologic abnormalities in asymptomatic subjects from the Osteoarthritis Initiative, with or without osteoarthritis (OA) risk factors. METHODS We studied 128 subjects with knee OA risk factors and 33 normal control subjects ages 45-55 years, with a body mass index of 18-27 kg/m(2) and no knee pain. Subjects were categorized according to exercise level, using the leisure activity component of the Physical Activity Scale for the Elderly, and by self-reported frequent knee-bending activities. Two radiologists graded the cartilage of the right knee on MR images, using the Whole-Organ MRI Score (WORMS). Cartilage was segmented, and compartment-specific T2 values were calculated. Differences between the exercise groups and knee-bending groups were determined using multiple linear and logistic regression models. RESULTS Among subjects with risk factors for knee OA, light exercisers had lower T2 values compared with sedentary and moderate/strenuous exercisers. When the sexes were analyzed separately, female moderate/strenuous exercisers had higher T2 values compared with sedentary individuals and light exercisers. Subjects without risk factors displayed no significant differences in T2 values according to exercise level. However, frequent knee-bending activities were associated with higher T2 values in both subjects with OA risk factors and those without OA risk factors and with more severe cartilage lesions in the group with risk factors. CONCLUSION In subjects at risk of knee OA, light exercise was associated with low T2 values, whereas moderate/strenuous exercise in women was associated with high T2 values. Higher T2 values and WORMS grades were also observed in frequent knee-benders, suggesting greater cartilage degeneration in these individuals.

Pediatric Endurance and Limb Strengthening (PEDALS) for Children With Cerebral Palsy Using Stationary Cycling: A Randomized Controlled Trial

Background Effective interventions to improve and maintain strength (force-generating capacity) and endurance are needed for children with cerebral palsy (CP). Objective This study was performed to examine the effects of a stationary cycling intervention on muscle strength, locomotor endurance, preferred walking speed, and gross motor function in children with spastic diplegic CP. Design This was a phase I randomized controlled trial with single blinding. Setting The interventions were performed in community-based outpatient physical therapy clinics. Outcome assessments were performed in university laboratories. Participants Sixty-two ambulatory children aged 7 to 18 years with spastic diplegic CP and Gross Motor Function Classification System levels I to III participated in this study. Intervention and Measurements Participants were randomly assigned to cycling or control (no-intervention) groups. Thirty intervention sessions occurred over 12 weeks. Primary outcomes were peak knee extensor and flexor moments, the 600-Yard Walk-Run Test, the Thirty-Second Walk Test, and the Gross Motor Function Measure sections D and E (GMFM-66). Results Significant baseline-postintervention improvements were found for the 600-Yard Walk-Run Test, the GMFM-66, peak knee extensor moments at 120°/s, and peak knee flexor moments at 30°/s for the cycling group. Improved peak knee flexor moments at 120°/s were found for the control group only, although not all participants could complete this speed of testing. Significant differences between the cycling and control groups based on change scores were not found for any outcomes. Limitations Heterogeneity of the patient population and intrasubject variability were limitations of the study. Conclusions Significant improvements in locomotor endurance, gross motor function, and some measures of strength were found for the cycling group but not the control group, providing preliminary support for this intervention. As statistical differences were not found in baseline-postintervention change scores between the 2 groups; the results did not demonstrate that stationary cycling was more effective than no intervention. The results of this phase I study provide guidance for future research.

Simultaneous acquisition of T1ρ and T2 quantification in knee cartilage: repeatability and diurnal variation.

To develop a robust sequence that combines T1ρ and T2 quantifications and to examine the in vivo repeatability and diurnal variation of T1ρ and T2 quantifications in knee cartilage.