Asymptomatic obese subjects with MR-based indications of knee OA have altered gait kinetics

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S97 Results: Table 1 presents the correlation coefficients between the radiographic grading sub scores and kinematic parameters. Correlations with the frontal plane kinematics showed to be the strongest, with R values going from 0.641 to 0.724. Furthermore, joint space demonstrated to be strongly correlated with frontal plane kinematics based on the high weight of this x-ray sub-score in the MLR. Results in the transverse and sagittal planes showed negative correlations ranging from -0.440 to -0.497. Results show that FO is the sub-score that is the most strongly correlated (in this case negative correlation) with kinematic parameters in the transverse plane. A residues analysis was also conducted to confirm a random distribution of the residues around zero (figure 1). The absence of error patterns means that the choice of a linear regression fits well the relationship between the kinematic parameters and radiographic sub scores. Conclusions: The frontal plane presented the strongest correlation between the x-ray grading scale and the knee kinematic parameters. This analysis showed that the higher the x-ray sub scores are, meaning a more advanced state of the disease, the higher the varus angle parameters during gait are. This strengthens the link between a dynamic varus alignment and medial TF compartment OA progression. Interestingly, joint space showed a strong influence on the correlations with kinematic parameters in frontal plane. The transverse and sagittal plane both showed a negative correlation, meaning that the higher the x-ray sub scores are, the lower the kinematic parameters will be. In the sagittal plane this translate to a more fixed flexion adaptation strategy to protect the knee and in the transverse plan to a more internally rotated tibia. An offset towards internal rotation was previously linked to faster progression of OA which could also support the link with higher FO score. Further investigations, with a larger and more homogeneous sample group should lead to stronger correlations and should better define the relationships between the knee 3D kinematic parameters and radiographic grading system. This study supports the involvement of dynamic biomechanical factors in the progression of the disease. Results give new insights to develop personalized treatment plan based on kinematic parameters and x-ray OA grading scales to potentially limit the progression of the disease. Plane Kinematic Parameter Radiographic Scorn (Estimate Coefficient) R^2 R p-value Abduction Adduction (frontal) Mean 0-10% of GC FA_TA (-0.212) JS (1.608) FO (0.971) TE (2.139) 0.383 0.619 0.005 Mean 1030% of GC FA_TA (-0.357) JS (1.663) FO (0.808) TE (1.406) 0.412 0.641 0.002 Mean 3050% of GC FA_TA (-0.268) JS (1.808) FO (1.051) TE (0.865) 0.524 0.724 <0.001 Mean 5060% of GC FA_TA (-0.488) JS (2.596) FO (1.359) 0.478 0.691 <0.001 Mean 0-60% of GC FA_TA (-0.415) JS (2.921) 0.431 0.656 <0.001 Internal/External Rotation (transverse) Initial Angle FA_TA (0.370) FO (-2.087) TE (2.386) SU (-1.301) 0.247 -0.497 0.015 Mean 0-20% of GC FA_TA (0.235) FO (-2.262) TE (1.029) 0.230 -0.479 0.009 Mean 0-60% of GC FA_TA (0.208) FO (-1.825) TE (1.004) 0.194 -0.440 0.025 Flexion Extension (sagittal) ROM loading – Initial angle FO (-0.854) TE (-1.398) SU (-2.988) 0.219 -0.468 0.013 Note: The Estimate Coefficient indicates by its sign if the correlation is positive or negative. 152 CORRELATION BETWEEN KNEE 3D KINEMATIC PARAMETERS DURING GAIT AND PATELLOFEMORAL OSTEOARTHRITIS RADIOGRAPHIC GRADING SCALE J. Blouin y, N. Mezghani z, T.D. Cooke xk, M. Brean k, A. Fuentes{. y Ecole technologie sup erieure, Montreal, QC, Canada; z TELUQ, Montreal, QC, Canada; xQueen’s Univ, Sch. of Rehabilitation Therapy, Perth, ON, Canada; kOAISYS, Perth, ON, Canada; { Emovi, Montreal, QC, Canada Purpose: Patellofemoral (PF) osteoarthritis (OA) is known to considerably limit activities of daily living. To assess the severity and progression of PF OA, skyline view radiographs are typically used. Radiographic grading scales have been developed to quantify the degenerative changes. Functional outcome measures (i.e knee kinematics) are also recognized to be good indicators of knee OA impairments. Few studies have been done in order to evaluate a link between radiographic scores and joint function. The objective of this study is to assess if PF knee OA grading scores are correlated with functional knee kinematics parameters. Methods: Twenty-three knees from 17 patients with a confirmed diagnosis of PF OA underwent a knee functional assessment (KneeKG, Laval, Canada) measuring, in clinic, 3D knee kinematic during treadmill gait. All patients had skyline view x-ray of their knees graded using OAISYS radiographic scheme. OAISYS scale is composed of 4 sub scores (JS (joint space), FO (femoral osteophytes), PE (patella erosion) and SU (subluxation)) and one total score (TS). These sub scores are applied to the most damaged knee compartment: medial or lateral. Knee kinematic parameters were evaluated in all three planes (sagittal, frontal, transverse,) going from punctual angle values at specific times of the gait cycle, ranges of motion (ROM), curve slopes and mean values for specific phases of the GC. Using SPSS Statistics software, Pearson’s Correlation Coefficient was first evaluated between TS and each kinematic parameter to find a preliminary result of the correlations. Secondly, kinematic parameters that showed correlation (p <0.05) were further investigated. A multiple linear regression (MLR) was done for each of these parameters as dependant variables and the sub scores (JS, FO, PE and SU) as independent variables. Results: Table 1 presents the correlation coefficients between the radiographic grading sub scores and kinematic parameters. Kinematic parameters in the frontal plane showed the strongest correlations; reaching for the lateral PF compartment (R 1⁄4 0.786) and for the medial PF compartment (R 1⁄4 -0.904). Transverse plane did not show any significant correlation. Interestingly, ranges of motion parameters in frontal and sagittal plane both showed strong inverse correlations with SU x-ray sub-score. A residues analysis showed a random distribution of the residues around zero (figure 1), confirming that the choice of a linear regression fits well the relationship between the kinematic parameters and radiographic sub scores. Conclusions: Radiographic grading sub scores JS and FO for the lateral PF compartment showed a correlation with frontal plane curve’s slope after the loading phase. More specifically, an increase of lateral compartment JS and FO scores (i.e. a lesser joint space and more lateral femoral osteophytes) is associated with an increase in varus knee alignment after loading. Although we were expecting an increase in dynamic valgus alignment, similar results were previously reported in the literature. Since this kinematicparameter gives a slope rather thanapunctualvalue, results cannot state if knees are in valgus or varus at the end of the loading phase. For the medial PF compartment, the higher FO and SU scores are, the lesser range of motion (ROM) is seen in the frontal plane during loading. Similar results were found when combining knees with medial or lateral PF compartment OA, a negative correlation was found between FO and SU score with ROM between the swing phase and the terminal stance phase, Both correlations characterize a stiffer knee during gait. Those results strengthen the involvement of dynamic biomechanical factors in the development of the disease. Results give insights to help