Kevin J. Deluzio

Knee and hip kinetics during normal stair climbing

Understanding joint kinetics during activities of daily living furthers our understanding of the factors involved in joint pathology and the effects of treatment. In this study, we examined hip and knee joint kinetics during stair climbing in 35 young healthy subjects using a subject-specific knee model to estimate bone-on-bone tibiofemoral and patello-femoral joint contact forces. The net knee forces were below one body weight while the peak posterior-anterior contact force was close to one body weight. The peak distal-proximal contact force was on average 3 times body weight and could be as high as 6 times body weight. These contact forces occurred at a high degree of knee flexion where there is a smaller joint contact area resulting in high contact stresses. The peak knee adduction moment was 0.42 (0.15) Nm/kg while the flexion moment was 1.16 (0.24) Nm/kg. Similar peak moment values, but different curve profiles, were found for the hip. The hip and knee posterior-anterior shear forces and the knee flexion moment were higher during stair climbing than during level walking. The most striking difference between stair ascent and level walking was that the peak patello-femoral contact force was 8 times higher during stair ascent. These data can be used as baseline measures in pathology studies, as input to theoretical joint models, and as input to mechanical joint simulators.

Neuromuscular and Lower Limb Biomechanical Differences Exist Between Male and Female Elite Adolescent Soccer Players During an Unanticipated Run and Crosscut Maneuver

Background Female athletes are 2 to 8 times more likely than male athletes to injure the anterior cruciate ligament during a noncontact athletic maneuver. Identifying anterior cruciate ligament injury risk factors in female athletes may help with the development of preventive training programs aimed at reducing injury rates. Hypothesis Differences between genders in lower limb kinematics, kinetics, and neuromuscular patterns will be identified in an adolescent soccer population during an unanticipated side-cut maneuver. Study Design Controlled laboratory study. Methods Forty-two elite adolescent soccer players (21 male and 21 female) performed an unanticipated side-cut maneuver, with the 3-dimensional kinematic, kinetic, and electromyographic lower limb data being analyzed using principal component analysis. Results The female athletes had higher gastrocnemius activity, normalized to maximal voluntary isometric contractions, and a mediolateral gastrocnemius activation imbalance that was not present in the male athletes during early stance to midstance of the side-cut. Female athletes demonstrated greater rectus femoris muscle activity throughout stance, and the only hamstring difference identified was a mediolateral activation imbalance in male athletes only. Female athletes performed the side-cut with less hip flexion and more hip external rotation and also generated a smaller hip flexion moment compared with the male athletes. Conclusion This is the first study to identify gender-related differences in gastrocnemius muscle activity during an unanticipated cutting maneuver. Clinical Relevance The increased and imbalanced gastrocnemius muscle activity, combined with increased rectus femoris muscle activity and reduced hip flexion angles and moments in female subjects, may all have important contributing roles in the higher noncontact ACL injury rates observed in female athletes.

Effect of a Home Program of Hip Abductor Exercises on Knee Joint Loading, Strength, Function, and Pain in People With Knee Osteoarthritis: A Clinical Trial

Background Hip abductor muscle weakness may result in impaired frontal-plane pelvic control during gait, leading to greater medial compartment loading in people with knee osteoarthritis (OA). Objective This study investigated the effect of an 8-week home strengthening program for the hip abductor muscles on knee joint loading (measured by the external knee adduction moment during gait), strength (force-generating capacity), and function and pain in individuals with medial knee OA. Design The study design was a nonequivalent, pretest-posttest, control group design. Setting Testing was conducted in a motor performance laboratory. Patients An a priori sample size calculation was performed. Forty participants with knee OA were matched for age and sex with a control group of participants without knee OA. Intervention Participants with knee OA completed a home hip abductor strengthening program. Measurements Three-dimensional gait analysis was performed to obtain peak knee adduction moments in the first 50% of the stance phase. Isokinetic concentric strength of the hip abductor muscles was measured using an isokinetic dynamometer. The Five-Times-Sit-to-Stand Test was used to evaluate functional performance. Knee pain was assessed with the Western Ontario and McMaster Universities Osteoarthritis Index questionnaire. Results Following the intervention, the OA group demonstrated significant improvement in hip abductor strength, but not in the knee adduction moment. Functional performance on the sit-to-stand test improved in the OA group compared with the control group. The OA group reported decreased knee pain after the intervention. Limitations Gait strategies that may have affected the knee adduction moment, including lateral trunk lean, were not evaluated in this study. Conclusions Hip abductor strengthening did not reduce knee joint loading but did improve function and reduce pain in a group with medial knee OA.

Effects of pelvic asymmetry and low back pain on trunk kinematics during sitting: a comparison with standing.

Study Design. A prospective study was conducted on a group of patients with unilateral nonspecific low back pain (LBP) and healthy controls. Objectives. To answer 3 questions: (1) Does pelvic asymmetry measured in standing affect the dynamics of motion performed in sitting? (2) Do patients with LBP perform trunk motions differently from non-LBP participants in sitting position? and (3) Do the kinematics of lateral flexion and axial rotation differ between sitting and standing positions? Summary of Background Data. The effect of pelvic asymmetry on trunk motion while sitting remains unclear. LBP has been associated with altered trunk kinematics in standing; however, there is limited information available describing trunk kinematics in sitting position in comparison to standing. Methods. Pelvic asymmetry was measured in 54 patients with unilateral nonspecific LBP and 59 control subjects. A motion-analysis system was used to test the range and symmetry of lateral flexion and axial rotation in sitting and standing positions. Bivariate correlations, regression, multivariate analysis of variance, and paired sample t tests were used to test for associations between variables and differences between groups. Results. We found significant: (1) correlations between pelvic asymmetry and asymmetric trunk motion performed in sitting, (2) differences between the LBP and control groups in patterns of trunk motion performed in a sitting posture, and (3) differences between kinematics of motions performed in sitting versus standing postures. Conclusions. This study shows a link between pelvic asymmetry and altered trunk motion in sitting position. We suggest that people with LBP may have a distinct compensatory mechanism, secondary to pelvic asymmetry, which puts the lumbar spine under higher stress. Movement asymmetry, rather than range of motion, may be a better indicator of disturbed function for people with LBP. Structural and functional asymmetries are factors that may be considered in the seating design and work environment.

Foot progression angle and the knee adduction moment: a cross-sectional investigation in knee osteoarthritis

OBJECTIVE To test the hypothesis that an association exists between the characteristics of the knee adduction moment and foot progression angle (FPA) in asymptomatic individuals and those with mild to moderate and severe knee osteoarthritis (OA). DESIGN Fifty asymptomatic individuals, 46 patients with mild to moderate and 44 patients with severe knee OA were recruited. Maximum knee adduction moment during late stance and principal component analysis (PCA) were used to describe the knee adduction moment captured during gait. Multiple regression models were used for each of the three group assignments to analyze the association between the independent variables and the knee adduction moment. RESULTS FPA explained a significant amount of the variability associated with the shape of the knee adduction moment waveform for the asymptomatic and mild to moderate groups (P<0.05), but not for the severe group (P>0.05). Walking velocity alone explained significant variance associated with the shape of the knee adduction moment in the severe OA group (P<0.05). CONCLUSION A toe out FPA was associated with altered knee adduction moment waveform characteristics, extracted using PCA, in asymptomatic individuals and those with mild to moderate knee OA only. These findings are directly implicated in medial knee compartment loading. This relationship was not evident in those with severe knee OA.

A PROCEDURE TO VALIDATE THREE-DIMENSIONAL MOTION ASSESSMENT SYSTEMS

The automation provided by computer-assisted motion-tracking systems allows for three-dimensional motion and force analysis. These systems combined with mathematical modelling are able to analyse quickly the intricate dynamics of human movement. Understanding the limitations of human motion analysis as performed by the present measurement techniques is essential for proper application of the results. It is necessary to validate the analysis system prior to subject testing. This paper provides a validation of an optoelectric motion-tracking system used in a dynamic knee assessment study. While the validation is shown with one particular system only, it is suggested that all systems used in two- or three-dimensional motion analysis should be tested similarly in the actual configuration used. Three simple mechanical representations of the human knee have been used in this validation. The first model provided an understanding of the source and behaviour of the error introduced to the accuracy of defining a vector between the recorded coordinates of two markers. The other two models investigated the effect of processing methods specific to the knee analysis project. Separating the markers by at least 180 mm is recommended to produce stable vectors. Relative joint angles could be calculated in all three planes of rotation. The error in calculating flexion and longitudinal rotation was less than 2.0 degrees, while calculating adduction introduced errors of 4.0 degrees. Force calculations were found to be within 8%. The system behaviour was found to be consistent within the calibrated volume about the force platform. Simple mechanical models combined with straightforward procedures can provide validation in terms of clinically relevant parameters.

Gait assessment in unicompartmental knee arthroplasty patients: Principal component modelling of gait waveforms and clinical status

The reduction and analysis of gait waveform data is a significant barrier to the clinical application of gait analysis. Principal component modelling of gait waveform data reduced the waveform data to measures of distance from normal and these distance measures were shown to be sensitive to changes in gait pattern associated with knee osteoarthritis and its treatment by unicompartmental arthroplasty. Principal component models were developed for eight knee kinematic and kinetic gait waveforms of a group of 30 normal elderly subjects. Each model consisted of a set of loading vectors, principal component scores and residuals. The loading vectors revealed the structure of the model and the scores and residuals were used as the distance measures about which confidence intervals were developed. Pre-operative and post-operative gait data from 13 unicompartmental arthroplasty (UCA) patients were used to demonstrate the application of the principal component models to pathological gait data. A gait score was developed to indicate the overall assessment of the kinematic and kinetic gait measures by the principal component models. This gait score was shown to agree with the clinical status as measured by the Knee Society Score (pre-op: rs=0.86; post-op: rs=0.73). Thus, the differences in gait pattern detected by the principal component models were clinical relevant.

The association between knee joint biomechanics and neuromuscular control and moderate knee osteoarthritis radiographic and pain severity

OBJECTIVE The objective of this study was to determine the association between biomechanical and neuromuscular factors of clinically diagnosed mild to moderate knee osteoarthritis (OA) with radiographic severity and pain severity separately. METHOD Three-dimensional gait analysis and electromyography were performed on a group of 40 participants with clinically diagnosed mild to moderate medial knee OA. Associations between radiographic severity, defined using a visual analog radiographic score, and pain severity, defined with the pain subscale of the WOMAC osteoarthritis index, with knee joint kinematics and kinetics, electromyography patterns of periarticular knee muscles, BMI and gait speed were determined with correlation analyses. Multiple linear regression analyses of radiographic and pain severity were also explored. RESULTS Statistically significant correlations between radiographic severity and the overall magnitude of the knee adduction moment during stance (r²=21.4%, P=0.003) and the magnitude of the knee flexion angle during the gait cycle (r²=11.4%, P=0.03) were found. Significant correlations between pain and gait speed (r²=28.2%, P<0.0001), the activation patterns of the lateral gastrocnemius (r²=16.6%, P=0.009) and the medial hamstring (r²=10.3%, P=0.04) during gait were found. The combination of the magnitude of the knee adduction moment during stance and BMI explained a significant portion of the variability in radiographic severity (R(2)=27.1%, P<0.0001). No multivariate model explained pain severity better than gait speed alone. CONCLUSIONS This study suggests that some knee joint biomechanical variables are associated with structural knee OA severity measured from radiographs in clinically diagnosed mild to moderate levels of disease, but that pain severity is only reflected in gait speed and neuromuscular activation patterns. A combination of the knee adduction moment and BMI better explained structural knee OA severity than any individual factor alone.

Comparative fixation of tibial plateau fractures using alpha-BSM, a calcium phosphate cement, versus cancellous bone graft.

Objectives: To compare the compressive strength of a bone substitute material (α-BSM™) to cancellous bone when used to fill a defect void in a cadaver model of a Schatzker II split depression fracture of the lateral tibial plateau. Design: Randomized, paired design. Setting: Biomedical engineering laboratory. Patients: Twenty-six human tibias were harvested from 13 cadavers. Three pairs of tibia fractured during preparation and were excluded. The remaining 10 matched pairs were randomized to fixation by using the bone substitute material or cancellous bone. Intervention: A split depression fracture of the lateral tibial plateau was created in each tibia by using reproducible methods. This fracture was stabilized with a stainless steel L-plate and screws and either α-BSM™ or cancellous bone to fill the defect void. Main Outcome Measurements: Stiffness of the elevated fragment in compression, total depression of the joint at 1000 N. Results: The α-BSM™ bone substitute displayed significantly greater stiffness than cancellous bone constructs in Schatzker II split depression fractures of the lateral tibial plateau (P < 0.0001). Plateau defects displaced significantly less at 1000N when using α-BSM™ in comparison to cancellous bone (P < 0.0001). Conclusions: In this cadaveric study, α-BSM™ is an effective bone substitute compared with cancellous bone graft for stabilizing split depression fractures of the lateral tibial plateau.

Gender differences exist in neuromuscular control patterns during the pre-contact and early stance phase of an unanticipated side-cut and cross-cut maneuver in 15-18 years old adolescent soccer players

Non-contact ACL injuries generally occur as the foot contacts the ground during cutting or landing maneuvers and the non-contact ACL injury rate is 2-8 times greater in females compared to males. To provide insight into the gender bias of this injury, this study set out to identify gender differences in the neuromuscular response of the quadriceps, hamstrings and gastrocnemii muscles in elite adolescent soccer players during the pre-contact and early stance phases of an unanticipated side-cut and cross-cut. For the early stance phase of the two maneuvers, females demonstrated greater rectus femoris activity compared to males. Throughout the pre-contact phase of the maneuvers, a rectus femoris activation difference was identified with females having an earlier and more rapid rise in muscle activity as initial ground contact approached. Females demonstrated greater lateral and medial gastrocnemii activity for the pre-contact and early stance phases of the side-cut and greater lateral gastrocnemii activity during early stance of the cross-cut. Timing of hamstring activity also differed between genders prior to foot contact. The differences suggest that the activation patterns observed in females might not be providing adequate joint protection and stability, thereby possibly having a contributing role towards increased non-contact ACL injuries in females.