Targeted exercises can improve biomechanical markers in individuals with knee osteoarthritis: A secondary analysis from a cluster randomized controlled trial.

BACKGROUND: It is not clear whether exercise therapy significantly improves knee biomechanics during gait in osteoarthritis (OA) patients. This study aimed to determine whether targeted exercises based on a knee kinesiography exam improve biomechanical markers (BMs) compared with conventional primary care (CPC) management. METHODS: This was a secondary analysis of a cluster randomized controlled trial in which patients were assigned to one of three groups: (1) Control (CPC), (2) Exercise, and (3) Exercise&Education. Fourteen known BMs in knee OA patients were assessed. The primary outcome was the global evolution ratio (GER), which was calculated as the sum of improved BMs over the sum of deteriorated BMs 6 months after baseline assessment. GER scores were categorized with three different sets of cut-off values into clinical levels: (a) Deteriorated, (b) Stabilized, and (c) Improved. Ordinal logistic regressions were performed on the per-protocol population to determine whether there was a relationship between group assignment and GER levels. RESULTS: Of the 221 eligible participants, 163 were included. Two different regression models showed that patients from Group 3 (Exercise&Education) were 2.5-times more likely to be in an upper GER level (i.e., Stabilized or Improved) than patients from the control group (both odds ratio (OR) > 2.46, Wald Χ2(1) ≥ 7.268, P ≤ 0.01). They also reported significantly more improvement in pain and function (Knee Injury and Osteoarthritis Outcome Score, both P ≤ 0.01). CONCLUSIONS: Results suggest that targeted exercises can improve biomechanical markers in knee OA patients compared with CPC treatment. Further studies are needed to confirm these findings and refine the biomechanical markers to address to maximize patients' clinical outcomes.

Biomechanical markers associations with pain, symptoms, and disability compared to radiographic severity in knee osteoarthritis patients: a secondary analysis from a cluster randomized controlled trial.

BACKGROUND: Conventional radiography is commonly used to diagnose knee osteoarthritis (OA), but also to guide clinical decision-making, despite a well-established discordance between radiographic severity and patient symptoms. The incidence and progression of OA is driven, in part, by biomechanical markers. Therefore, these dynamic markers may be a good metric of functional status and actionable targets for clinicians when developing conservative treatment plans. The aim of this study was to assess the associations between biomechanical markers and self-reported knee function compared to radiographic severity. METHODS: This was a secondary analysis of data from a randomized controlled trial (RCT) conducted in primary care clinics with knee OA participants. Correlation coefficients (canonical (ρ) and structural (Corr)) were assessed between the Knee Injury and Osteoarthritis Outcome Score (KOOS) and both, radiographic OA severity using the Kellgren-Lawrence grade, and three-dimensional biomechanical markers quantified by a knee kinesiography exam. Significant differences between coefficients were assessed using Fischer's z-transformation method to compare correlations from dependent samples. RESULTS: KOOS and biomechanical data were significantly more associated than KOOS and X-ray grading (ρ: 0.41 vs 0.20; p < 0.001). Structural correlation (Corr) between KOOS and X-ray grade was 0.202 (4% of variance explained), while individual biomechanical markers, such as the flexion during loading, explained up to 14% of KOOS variance (i.e., Corr2). Biomechanical markers showed the strongest associations with Pain and Activity of Daily Living KOOS subscales (both > 36% variance explained), while X-ray grading was most associated with Symptoms subscale (21% explained; all p ≤ 0.001). CONCLUSIONS: Knee biomechanical markers are associated with patient-reported knee function to a greater extent than X-ray grading, but both provide complementary information in the assessment of OA patients. Understanding how dynamic markers relate to function compared to radiographic severity is a valuable step towards precision medicine, allowing clinicians to refine and tailor therapeutic measures by prioritizing and targeting modifiable biomechanical markers linked to pain and function. TRIAL REGISTRATION: Original RCT was approved by the Research Ethics Boards of École de technologie supérieure (H20150505) and Centre hospitalier de l'Université de Montréal (CHUM-CE.14.339), first registered at https://www.isrctn.com/ (ID-ISRCTN16152290) on May 27, 2015.

Graphical-based multivariate analysis for knee joint clinical and kinematic data correlation assessment.

A large amount of data including joint kinematics, joint kinetics, clinical and functional measurements constitutes the clinical gait analysis basis which is a process whereby quantitative gait information are collected to aid in clinical decision-making. Therefore, better understanding the relationship between the biomechanical and clinical data for the knee osteoarthritis (OA) patient is for a relevant importance. It's the purpose of this paper, which aims to analyze and visualize the correlation structure between biomechanical characteristics and clinical symptoms, and thus to provide an additional knowledge from the coupling of these parameters that will be useful for the pathology assessment of knee-joint disease in the end-staged knee OA patients. We perform two multivariate statistical approaches, first, a Canonical Correlation Analysis (CCA) to assess the multivariate association and, second, a graphical- based representation of the multivariate correlation to better understand the association between these multivariate data. Results show the usefulness of using such multivariate approaches to highlight association and specific correlation structure between the features and to extract meaningful information.

Morphologic and radiologic parameters correlating to shoulder function at diagnosis for patients with rotator cuff tear.

BACKGROUND: The magnetic resonance imaging (MRI) parameters used to diagnose rotator cuff tears are weakly correlated to shoulder function. Our hypothesis was that adding 3-dimensional morphologic parameters resulting from biplanar radiographs (3DXR parameters) to the MRI parameters would improve this correlation. METHODS: We assessed 52 patients with rotator cuff tears with an EOS Imaging radiographic examination, MRI study, and clinical evaluation of the shoulder, as well as the Constant score. The bones of the 52 shoulders were reconstructed 3-dimensionally, and eleven 3DXR parameters were automatically extracted. First, the trueness and reliability of these parameters were evaluated. Then, bivariate correlations between each parameter and the Constant score were made. A linear regression model was subsequently built to correlate the 11 parameters and 5 MRI findings with shoulder function at diagnosis, as assessed by the Constant score. RESULTS: The parameters showed good trueness and reliability of most 3DXR parameters. Supraspinatus tear extension, muscle atrophy, and the distance between the greater and deltoid tuberosities were the only parameters with a statistically significant correlation to a lower Constant score (P < .05) in the bivariate study. These correlations were either weak or negligible. A regression model was successfully built with one MRI parameter and four 3DXR parameters. Correlation to function increased from 16.7% to 43.3% with this model. CONCLUSION: For patients with rotator cuff tears, the combination of MRI and 3DXR parameters of the shoulder in a linear regression model improves the correlation with the Constant score (shoulder function) at diagnosis.

Inertial motion capture validation of 3D knee kinematics at various gait speed on the treadmill with a double-pose calibration.

BACKGROUND: Inertial motion capture (IMC) is rapidly gaining in popularity to evaluate gait in clinical settings. Previous examinations of IMC knee kinematics were often limited to the sagittal plane and IMC calibration has not been thoroughly investigated. RESEARCH QUESTION: The objective was to validate IMC 3D knee kinematics calibrated with a double-pose during gait with reference to optical motion capture (OMC). The hypotheses are that IMC can estimate adequately knee kinematics and that both systems will detect similarly the changes with gait speed. METHODS: Twenty-four healthy participants walked on the treadmill at gait speed of 0.6, 0.8, 1.0 and 1.2 m/s. Knee kinematics were obtained simultaneously with two magnetic and inertial measurement units and passive markers fixed on the KneeKG system. OMC was calibrated with a functional anatomical approach and the IMC with a double-pose. RESULTS: Root mean square differences of the two systems yielded 3-6° for knee flexion, adduction and external rotation. Knee kinematics were more similar during the stance phase than the swing phase. Gait speed showed a significant progressive effect on the three knee angles that was similarly detected by the two systems. SIGNIFICANCE: IMC 3D knee kinematics can be obtained independently with a simple calibration and only two magnetic and inertial measurement units at an acceptable level of error especially during stance.

A multi-arm cluster randomized clinical trial of the use of knee kinesiography in the management of osteoarthritis patients in a primary care setting.

Objective: An important clinical gap reported by primary care physicians (PCPs) in managing knee osteoarthritis patients is the lack of validated tools to help them guide conservative treatment decision-making. This study aimed at evaluating the clinical utility of adding to current medical management (CMM) by PCPs, a dynamic knee kinesiography (KneeKG) exam assessing biomechanical risk factors linked to osteoarthritis progression.Design: In this 6-month cluster randomized controlled trial, primary care clinics were randomized into three groups: 1-CMM by PCPs, 2-CMM+KneeKG, and 3-CMM+KneeKG+Education (a self-management education session and two follow-up group meetings). Primary outcomes were scores on the Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales and overall score.Results: Of the 894 patients referred from 87 clinics, 515 participated, 449 (87.2%) completed the study. At 6-month follow-up, patients in both KneeKG groups reported statistically significant improvement on the KOOS overall score (Group2: +5.5; Group3: +5.0), and on the symptoms, pain, and activities of daily living subscales compared to control group (all p < 0.05). They also reported significantly higher satisfaction levels with global care (both p < 0.01). Group 3-CMM+KneeKG+Education showed statistically significant improvements in objective functional tests as well as greater global impression of change in pain, function, quality of life, and global condition (all p < 0.05).Conclusions: Results demonstrated significant improvements in terms of pain, function, and satisfaction in KneeKG groups relative to the CMM. Adding education and supervision further improves clinical outcomes. These findings may support the added value of a KneeKG exam in assisting PCPs in the management of knee osteoarthritis patients.

Hip-Knee-Ankle (HKA) angle modification during gait in healthy subjects.

BACKGROUND: Achieving a neutral static Hip-Knee-Ankle angle (sHKA) measured on radiographs has been considered a factor of success for total knee arthroplasty (TKA). However, recent studies have shown that sHKA seems to have no effect on TKA survivorship. sHKA is not representative of the dynamic loading occurring during gait, unlike the dynamic HKA (dHKA). RESEARCH QUESTION: The primary objective was to see if the sHKA is predictive of the dynamic HKA (dHKA). A secondary objective was to document to what degree the dHKA changes during gait. METHODS: We analysed 3D knee kinematics during gait of a cohort of 90 healthy individuals with the KneeKG™ system. dHKA was calculated and compared with sHKA. Knees were considered "Stable" if the dHKA remained in valgus or varus for greater than 95% of the corresponding phase, and "Changer" otherwise. Patient characteristics of the Stable and Changer knees were compared to find associated factors. RESULTS: Absolute variation of dHKA during gait was 10.9 ± 5.3° for the whole cohort. The variation was less for the varus knees (10.3 ± 4.8°), than for the valgus knees (12.8 ± 6.1°, p = 0.008). We found low to moderate correlations (r = 0.266 to 0.553, p < 0.001) between sHKA and dHKA values for varus knees and no significant correlation for valgus knees. Twenty two percent (36/165) of the knees were considered Changers. The proportion of knees that were Changers was 15% of the varus versus 39% of the valgus (p < 0.001). SIGNIFICANCE: Lower limb radiographic measures of coronal alignment have limited value for predicting dynamic measures of alignment during gait.

A multivariate relationship between the kinematic and clinical parameters of knee osteoarthritis population.

BACKGROUND: Biomechanical and clinical parameters contribute very closely to functional evaluations of the knee joint. To better understand knee osteoarthritis joint function, the association between a set of knee biomechanical data and a set of clinical parameters of an osteoarthritis population (OA) is investigated in this study. METHODS: The biomechanical data used here are a set of characteristics derived from 3D knee kinematic patterns: flexion/extension, abduction/adduction, and tibial internal/external rotation measurements, all determined during gait recording. The clinical parameters include a KOOS questionnaire and the patient's demographic characteristics. Canonical correlation analysis (CCA) is used (1) to evaluate the multivariate relationship between biomechanical data and clinical parameter sets, and (2) to cluster the most correlated parameters. Multivariate models were created within the identified clusters to determine the effect of each parameter's subset on the other. The analyses were performed on a large database containing 166 OA patients. RESULTS: The CCA results showed meaningful correlations that gave rise to three different clusters. Multivariate linear models were found explaining the subjective clinical parameters by evaluating the biomechanical data contained within each cluster. CONCLUSION: The results showed that a multivariate analysis of the clinical symptoms and the biomechanical characteristics of knee joint function allowed a better understanding of their relationships.

Can total knee arthroplasty restore the correlation between radiographic mechanical axis angle and dynamic coronal plane alignment during gait?

BACKGROUND: Total knee arthroplasty (TKA) is the treatment of choice for end-stage knee osteoarthritis. Postoperative static knee alignment has been recognized as a key component of successful surgery. A correction toward the kinematics of a native knee is expected after TKA, with an aim for neutral mechanical alignment. The evolution of frontal plane knee kinematics is not well understood. METHODS: Nineteen patients awaiting TKA were recruited. Three-dimensional knee kinematics during treadmill gait were assessed pre-operatively, 12 months after surgery, and compared to a control group of 17 asymptomatic participants. RESULTS: Mean radiographic mechanical alignment was corrected from 5.4°â€¯±â€¯5.0 (Standard Deviation) varus pre-operatively to 0.1°â€¯±â€¯2.0 (Standard Deviation) valgus postoperatively (P = 0.002). Mean stance coronal plane alignment decreased from 6.7°â€¯±â€¯4.0 (Standard Deviation) varus per-operatively to 2.1°â€¯±â€¯3.8 (Standard Deviation) postoperatively (P = 0.001). Correlation between radiographic mechanical axis angle and dynamic frontal plane alignment during gait, before and after surgery, was weak (pre-operative R = 0.41; postoperative R = 0.13) compared to control (R = 0.88). In the sagittal plane, TKA patients maintained their pre-operative stiff knee gait adaptation. Postoperative transverse plane kinematics suggested restoration of external tibial rotation during swing after TKA compared to control (Pre-operative 3.1°, postoperative 6.8°, control 7.1°, P = 0.05). CONCLUSION: The lack of correlation between static and dynamic alignment suggests that static radiographic coronal alignment of the knee does not accurately predict dynamic behavior. In the sagittal plane, pre-operative gait adaptations were still present 12 months after surgery, supporting the need for a functional assessment to guide postoperative rehabilitation following TKA.

Kinematic alignment in total knee arthroplasty better reproduces normal gait than mechanical alignment.

PURPOSE: Kinematic alignment technique for TKA aims to restore the individual knee anatomy and ligament tension, to restore native knee kinematics. The aim of this study was to compare parameters of kinematics during gait (knee flexion-extension, adduction-abduction, internal-external tibial rotation and walking speed) of TKA patients operated by either kinematic alignment or mechanical alignment technique with a group of healthy controls. The hypothesis was that the kinematic parameters of kinematically aligned TKAs would more closely resemble that of healthy controls than mechanically aligned TKAs. METHODS: This was a retrospective case-control study. Eighteen kinematically aligned TKAs were matched by gender, age, operating surgeon and prosthesis to 18 mechanically aligned TKAs. Post-operative 3D knee kinematics analysis, performed with an optoelectronic knee assessment device (KneeKG®), was compared between mechanical alignment TKA patients, kinematic alignment TKA patients and healthy controls. Radiographic measures and clinical scores were also compared between the two TKA groups. RESULTS: The kinematic alignment group showed no significant knee kinematic differences compared to healthy knees in sagittal plane range of motion, maximum flexion, abduction-adduction curves or knee external tibial rotation. Conversely, the mechanical alignment group displayed several significant knee kinematic differences to the healthy group: less sagittal plane range of motion (49.1° vs. 54.0°, p = 0.020), decreased maximum flexion (52.3° vs. 57.5°, p = 0.002), increased adduction angle (2.0-7.5° vs. - 2.8-3.0°, p < 0.05), and increased external tibial rotation (by a mean of 2.3 ± 0.7°, p < 0.001). The post-operative KOOS score was significantly higher in the kinematic alignment group compared to the mechanical alignment group (74.2 vs. 60.7, p = 0.034). CONCLUSIONS: The knee kinematics of patients with kinematically aligned TKAs more closely resembled that of normal healthy controls than that of patients with mechanically aligned TKAs. This may be the result of a better restoration of the individual's knee anatomy and ligament tension. A return to normal gait parameters post-TKA will lead to improved clinical outcomes and greater patient satisfaction. LEVEL OF EVIDENCE: III.

Quantification of joint alignment and stability during a single leg stance task in a knee osteoarthritis cohort.

BACKGROUND: Knee osteoarthritis alters joint stability but its kinematics during functional weight-bearing tasks remain unclear. We propose and validate an assessment technique for the quantification of knee alignment and stability in patients during a short single leg stance task. METHODS: Three-dimensional knee kinematics were acquired non-invasively from 31 knee osteoarthritis patients (subdivided as moderate or severe) and 15 asymptomatic individuals during six short single-leg stance tasks. Data of participants achieving ≥3 trials were retained. From flexion-extension signals, a data treatment method compared the average between-trial root-mean-square error (RMSE) across trial triplets, and the average within-trial range of movement (RoM) for two data windows. From secondary knee motions (ab/adduction and int/external rotations, anteroposterior and mediolateral translations), we extracted measures characterizing alignments (mean), largest deviations (maximum, minimum), and extent of micro-adjustments (RoM, length of knee excursion). Their sensitivity to disease and severity was determined using an ANOVA, and between-trial repeatability using ICC2,3. RESULTS: Ninety-four percent of patients achieved ≥3 trials. The retained trial triplet and window reduced the RMSE (2.15 to 1.54) and RoM (4.9° to 1.77°) for flexion-extension. Mean, minimum, and maximum measures were sensitive to disease for anteroposterior translations, and to severity for ab/adduction (P < 0.05). High repeatability was found for those measures (ICC ≥0.84). RoM and length of knee excursion, although sensitive to disease for anteroposterior translations, had lower ICC. CONCLUSION: The proposed technique is feasible and exposed measures of knee alignment sensitive to knee osteoarthritis, for instance, an anterior femoral shift and an increased adduction malalignment with greater severity.

Healthy 3D knee kinematics during gait: Differences between women and men, and correlation with x-ray alignment.

BACKGROUND: Normal 3D knee kinematics during gait is still not well understood, especially regarding differences between women and men. RESEARCH QUESTION: The objective of the present study was to characterize 3D knee kinematics during gait in healthy women and men with a validated tool. METHODS: Knee kinematics was analysed with the KneeKG™ system in 90 healthy subjects (49 females and 41 males). 3D knee rotations were compared between women and men, and between right and left knees. Each subject underwent full-length weight-bearing x-rays. Correlations between abduction-adduction angles and lower-limb alignment measures on x-rays were assessed. RESULTS: In the frontal plane, 2.0-5.0° more abduction occurred in women compared to men (0.000 ≤ p ≤ 0.015) throughout the entire gait cycle. In the transverse plane, 2.4-3.7° more external tibial rotation was seen in women than in men (0.002 ≤ p ≤ 0.041) during the initial and mid-swing phases. No difference was found between the right and left knees. Low correlations (-0.52 ≤ r≤-0.41, p < 0.001) were observed between radiographic hip-knee-ankle angle (HKA) and abduction-adduction angles throughout the stance phase. SIGNIFICANCE: Kinematic differences between women and men in the frontal plane can be partly explained by their anatomical differences: women were less in varus than men (HKA of -0.8° vs. -2.6°, p < 0.001). Our study contributes to a better understanding of healthy 3D knee kinematics during gait and highlights the need for accounting of gender differences in future investigations. Better knowledge of natural knee kinematics will be helpful in assessing pathological gait patterns or determining the efficiency of conservative and surgical treatments to restore normal kinematics.

Rotator Cuff Tear Morphologic Parameters at Magnetic Resonance Imaging: Relationship With Muscle Atrophy and Fatty Infiltration and Patient-Reported Function and Health-Related Quality of Life.

OBJECTIVE: The aim of this study was to determine the relationship between rotator cuff tear (RCT) morphologic parameters and muscle atrophy and fatty infiltration, and patient-reported outcome measures, in patients with symptomatic full-thickness RCT. METHODS: Rotator cuff tear location, length, width, thickness, and musculotendinous junction position were assessed in 57 magnetic resonance imaging scans and correlated to the outcome measures using multivariate regression analysis. RESULTS: Supraspinatus tendon tear length (odds ratio [OR], 2.218; 95% confidence interval [CI], 1.460-3.370), supraspinatus musculotendinous junction position (OR, 2.037; 95% CI, 1.322-3.137), and infraspinatus tendon tear width (OR, 2.371; 95% CI, 1.218-4.615) were identified as the strongest determinants of supraspinatus muscle atrophy, supraspinatus muscle fatty infiltration, and infraspinatus muscle fatty infiltration, respectively. CONCLUSIONS: The extent of supraspinatus tendon and musculotendinous junction retraction influences the development of supraspinatus muscle atrophy and fatty infiltration, whereas the extent of infraspinatus tendon tear width influences the development of infraspinatus muscle fatty infiltration. Morphologic parameters defining RCT at magnetic resonance imaging did not correlate with clinical shoulder function scores.

Comparison of soft tissue artifact and its effects on knee kinematics between non-obese and obese subjects performing a squatting activity recorded using an exoskeleton.

BACKGROUND: Rigid attachment systems are one of the methods used to compensate for soft tissue artifact (STA) inherent in joint motion analyses. RESEARCH QUESTION: The goal of this study was to quantify STA of an exoskeleton design to reduce STA at the knee, and to assess the accuracy of 3D knee kinematics recorded with the exoskeleton in non-obese and obese subjects during quasi-static weight-bearing squatting activity using biplane radiography. METHODS: Nine non-obese and eight obese subjects were recruited. The exoskeleton was calibrated on each subject before they performed a quasistatic squatting activity in the EOS® imaging system. 3D models of exoskeleton markers and knee bones were reconstructed from EOS® radiographs; they served to quantify STA and to evaluate differences between the markers and bones knee kinematics during the squatting activity. RESULTS: The results showed that STA observed at the femur was larger in non-obese subjects than in obese subjects in frontal rotation (p = 0.004), axial rotation (p = 0.000), medio-lateral displacement (p = 0.000) and antero-posterior displacement (p = 0.019), while STA observed at the tibia was lower in non-obese subjects than in obese subjects for the three rotations (p < 0.05) and medio-lateral displacement (p = 0.015). Differences between the markers and bones knee kinematics increased with knee flexion and were similar in both groups, except for abduction-adduction: 4.9° for non-obese subjects against 2.3° for obese subjects (p = 0.011). SIGNIFICANCE: This study demonstrated that STA at the femur and its impact on knee abduction-adduction using a specific exoskeleton were greater among non-obese subjects than obese subjects, which is encouraging for future biomechanical studies on pathologies such as osteoarthritis.

Total knee arthroplasty with unexplained pain: new insights from kinematics.

INTRODUCTION: Up to 20% of total knee arthroplasty patients remain unsatisfied post-surgery, and a large proportion of them report anterior knee pain. This study aims to verify whether patients who experience anterior knee pain after total knee arthroplasty (TKA) will exhibit kinematic characteristics similar to those associated with patellofemoral syndrome, including in the frontal and transverse planes. MATERIALS AND METHODS: Using four different assessment methods [radiological, patient-reported outcome, musculoskeletal assessment with functional performance testing, and a 3D kinematic assessment during gait], the clinical and 3D knee kinematic profiles of three groups were compared: a painful and an asymptomatic TKA group and a healthy control group. All three groups underwent a three-dimensional kinematic knee assessment while walking on a treadmill. Prosthetic component rotation was assessed through a CT scan measurement performed by one experienced radiologist. Flexion/extension, ab/adduction, and tibial internal rotation curves were compared, and significant differences were highlighted through ANCOVA analysis performed on SPSS. RESULTS: A total of 62 knees were evaluated, 24 asymptomatic, 21 painful, and 17 control. A dynamic flexion contracture during gait was observed in the painful group, which was associated with a lack of flexibility of the thigh muscles. Moreover, painful TKA cases exhibited a valgus alignment (- 1.5°) during stance, which increases the Q angle and lateralizes the patella. Finally, CT scan evaluation of painful total knee arthroplasty patients revealed that their combined components rotation was in slight internal rotation (- 1.4°, SD 7.0°). CONCLUSIONS: Painful TKA patients presented three well-known characteristics that tend to increase patellofemoral forces and that could be the cause of the unexplained pain: a stiff knee gait, a valgus alignment when walking, and combined TKA components slightly internally rotated.

Mechanical biomarkers of medial compartment knee osteoarthritis diagnosis and severity grading: Discovery phase.

OBJECTIVE: To investigate, as a discovery phase, if 3D knee kinematics assessment parameters can serve as mechanical biomarkers, more specifically as diagnostic biomarker and burden of disease biomarkers, as defined in the Burden of Disease, Investigative, Prognostic, Efficacy of Intervention and Diagnostic classification scheme for osteoarthritis (OA) (Altman et al., 1986). These biomarkers consist of a set of biomechanical parameters discerned from 3D knee kinematic patterns, namely, flexion/extension, abduction/adduction, and tibial internal/external rotation measurements, during gait recording. METHODS: 100 medial compartment knee OA patients and 40 asymptomatic control subjects participated in this study. OA patients were categorized according to disease severity, by the Kellgren and Lawrence grading system. The proposed biomarkers were identified by incremental parameter selection in a regression tree of cross-sectional data. Biomarker effectiveness was evaluated by receiver operating characteristic curve analysis, namely, the area under the curve (AUC), sensitivity and specificity. RESULTS: Diagnostic biomarkers were defined by a set of 3 abduction/adduction kinematics parameters. The performance of these biomarkers reached 85% for the AUC, 80% for sensitivity and 90% for specificity; the likelihood ratio was 8%. Burden of disease biomarkers were defined by a 3-decision tree, with sets of kinematics parameters selected from all 3 movement planes. CONCLUSION: The results demonstrate, as part of a discovery phase, that sets of 3D knee kinematic parameters have the potential to serve as diagnostic and burden of disease biomarkers of medial compartment knee OA.

Can generic knee joint models improve the measurement of osteoarthritic knee kinematics during squatting activity?

Knee joint kinematics derived from multi-body optimisation (MBO) still requires evaluation. The objective of this study was to corroborate model-derived kinematics of osteoarthritic knees obtained using four generic knee joint models used in musculoskeletal modelling - spherical, hinge, degree-of-freedom coupling curves and parallel mechanism - against reference knee kinematics measured by stereo-radiography. Root mean square errors ranged from 0.7° to 23.4° for knee rotations and from 0.6 to 9.0 mm for knee displacements. Model-derived knee kinematics computed from generic knee joint models was inaccurate. Future developments and experiments should improve the reliability of osteoarthritic knee models in MBO and musculoskeletal modelling.

Effects of Prosthetic Mismatch and Subscapularis Tear on Glenohumeral Contact Patterns in Total Shoulder Arthroplasty: A Numerical Musculoskeletal Analysis.

Prosthetic components' mismatch and subscapularis (SC) tear are determining factors for glenoid failure complication in nonconforming total shoulder arthroplasty (NC-TSA). Risk factors are linked to glenoid prosthetic loading. However, the mechanisms underlying the clinical observations remain unclear. This study assessed the combined impact of mismatch and subscapularis tear on glenoid loading. It was assumed that adequate glenoid loading was associated with minimal, but non-null, humeral head translations and contact pressure, as well as with maximal glenoid contact area, and that the center of pressure (COP) on the glenoid would have a centered displacement pattern. A numerical model was used to achieve two objectives. The first was to verify whether an optimum mismatch existed, for which failure risk would be minimal. The second was to explore the effect of subscapularis tear on the position of applied forces on the glenoid. A shoulder AnyBody musculoskeletal model was adapted to the arthroplasty context by introducing humeral head translations and contact between implants. Ten simulations were computed to compare combinations of varying mismatches (1.4 mm, 3.4 mm, 6.4 mm, 8.6 mm, and 9 mm) with two shoulder conditions (intact-muscle or subscapularis tear). Humeral head translations, center-of-pressure, contact area, contact pressure, and glenohumeral joint contact forces were numerically estimated. Mismatches between 3.4 mm and 6.4 mm were associated with the most minimal humeral translations and contact pressure, as well as with maximal contact area. Center of pressure displacement pattern differed according to shoulder condition, with an outward anterior tendency in presence of tear.

Sonographic Visualization of the Rotator Cable in Patients With Symptomatic Full-Thickness Rotator Cuff Tears: Correlation With Tear Size, Muscular Fatty Infiltration and Atrophy, and Functional Outcome.

OBJECTIVES: To assess the prevalence of sonographic visualization of the rotator cable in patients with symptomatic full-thickness rotator cuff tears and asymptomatic controls and to correlate rotator cable visualization with tear size, muscular fatty infiltration and atrophy, and the functional outcome in the patients with rotator cuff tears. METHODS: Fifty-seven patients with rotator cuff tears and 30 asymptomatic volunteers underwent shoulder sonography for prospective assessment of the rotator cable and rotator cuff tear and responded to 2 functional outcome questionnaires (shortened Disabilities of the Arm, Shoulder, and Hand [QuickDASH] and Constant). In the patients with rotator cuff tears, appropriate tests were used to correlate rotator cable visualization with the tear size, functional outcome, muscular fatty infiltration, and atrophy. RESULTS: The patients with rotator cuff tears included 25 women and 32 men (mean age,57 years; range, 39-67 years), and the volunteers included 13 women and 17 men (mean age, 56 years; range, 35-64 years). The rotator cable was identified in 77% (23 of 30) of controls and 23% (13 of 57) of patients with rotator cuff tears. In the patients, nonvisualization of the rotator cable correlated with larger tears (P < 0.001) and higher grades of supraspinatus atrophy (P = .049) and fatty infiltration (P = .022). There was no significant correlation with functional outcome scores (QuickDASH, P = .989; Constant, P = .073) or infraspinatus fatty infiltration (P = .065). CONCLUSIONS: Nonvisualization of the rotator cable was more prevalent in patients with symptomatic rotator cuff tears than asymptomatic controls and was associated with a larger tear size and greater supraspinatus fatty infiltration and atrophy. Diligent assessment of the supraspinatus muscle should be done in patients with rotator cuff tears without a visible rotator cable, as the integrity of these anatomic structures may be interdependent.

Clinical and Biomechanical Evaluations of Staged Bilateral Total Knee Arthroplasty Patients with Two Different Implant Designs.

BACKGROUND: Various implants of total knee arthroplasty (TKA) are used in clinical practice and each presents specific design characteristics. No implant managed this day to reproduce perfectly the biomechanics of the natural knee during gait. OBJECTIVES: We therefore asked whether (1) differences in tridimensional (3D) kinematic data during gait could be observed in two different designs of TKA on the same patients, (2) if those gait kinematic data are comparable with those of asymptomatic knees and (3) if difference in clinical subjective scores can be observed between the two TKA designs on the same patient. METHODS: We performed knee kinematic analysis on 15 patients (30 TKAs) with two different TKA implant designs (Nexgen, Zimmer and Triathlon, Stryker) on each knee and on 25 asymptomatic subjects (35 knees). Clinical evaluation included range of motion, weight bearing radiographs, questionnaire of joint perception, KOOS, WOMAC and SF-12. RESULTS: Comparison between TKAs and asymptomatic knees revealed that asymptomatic knees had significantly less knee flexion at initial contact (p < 0.04) and more flexion for most of the swing phase (p between 0.004 and 0.04). Asymptomatic knees also had less varus at loading response, during stance phase and during most of the swing phase (p between 0.001 - 0.05). Transverse plane analysis showed a tendency for asymptomatic knees to be more in internal rotation during stance phase (p 0.02 - 0.04). Comparing both TKA designs, Nexgen(TM) implant had significantly more flexion at the end of swing phase (p = 0.04) compared to knees with the Triathlon(TM) implant. In frontal plane, from initial contact to maximum mid stance angle and between the mean mid stance angle and initial contact Nexgen(TM) TKA had significantly more adduction (varus, p =0.02 - 0.03). Clinical scores of both TKAs did not have significant difference. CONCLUSIONS: TKA with the tested implants did not reproduce natural knee kinematics during gait. In our cohort of patients, TKA implant design translated in limited kinematics differences during gait and on clinical results.