Evaluate precisely and reproducibly tridimensional positioning of bone tunnels in anterior cruciate ligament reconstructions (ACL). To propose biplanar stereoradiographic imaging as a new reference in tridimensional evaluation of ACL reconstruction (ACLR). Comparing knee 3D models issued from EOStm low-irradiation biplanar X-Ray with those issued from computed tomography (CT-Scan) high definition images will allow a bone morphological description of a previously unseen precision.

We carried out the transfer of 3D models from EOStm X-Ray images obtained from 10 patients in the same reference frame with models issued from CT-Scan. Two evaluators reconstructed both pre-operative and post-operative knees, using two different stereoradiographic projections, for a total of 144 knee 3D models from EOStm. A surface analysis by distance mapping allowed us to know the differences or errors between the homologous points of the EOStm and CT reconstructions, the latter being our “bronze-standard”.

At the femur, we obtained a mean (95% confidence level) error of 1.5 mm (1.3–1.6) between the EOStm models compared to the Arthro-CT segmentations when using AP-LAT incidences, compared to 1 mm (1.0 – 1.1) with oblique projections. For the tunnels placement analysis, the total radius difference between EOStm and Arthro-CT's femoral tunnel apertures was 0.8 mm (0.4–1.2) in AP-LAT and 0.6 mm (0.0–1.2) in oblique views. These femoral apertures positioning on EOStm models were within 4.3 mm (3.0–5.7) of their homologues on CT-Scan models, 4.6 mm (3.5–5.6) with the oblique views. Furthermore, 9.3o (7.2–11.4) of difference in direction between femoral tunnels from EOStm models and CT reconstructions is obtained with AP-LAT projections, 8.3o (6.6–10) with obliques views. Measures of these parameters were also performed at the tibia.

According to the intra and inter-reproducibility analysis of our knee 3D models, EOStm biplanar X-Ray images prove to be fast, efficient and precise in the design of ACLR 3D models with respect to CT-Scan. Our results also propose the recourse of oblique stereoradiographic projections for the realization of knee 3D models. These models will be subjects of further analysis and will allow us eventually to propose a new frame of reference guiding the positioning of the tunnels in the ACLR.

Purpose: To determine if some subsets of healthy subjects displayed other than a typical gait pattern and to identify which subsets have similar kinematic pattern to patients with knee osteoarthritis.

Methods: The healthy subject dataset consisted of 106 asymptomatic volunteers. These subjects were over 17 years of age, pain-free, had no record of surgery to the lower limb and no evidence or history of arthritic disease at the time of testing. The patient population consisted of 12 patients diagnosed with knee OA, evaluated within 6 months prior to the tests. The 3D movements of right knee joint were recorded using a functional knee analyzer with magnetic sensors while subjects walked on a treadmill at their own preferred speed. The magnetic sensors are non-invasive electromagnetic devices, which track the 3D positions and orientations of sensors relative to a source. The system has been shown to be accurate, especially in the frontal and transversal planes. K-means clustering analysis was chosen to identify the gait patterns among healthy subjects based on three components of the knee joint angles, and analyses of variance were performed to determine which parameters were different between subsets.

Results: Three gait groups or patterns were identified in the healthy subjects. The first group (G1) was characterized by a kinematic profile similar to the OA group. The second group (G2) had the highest external rotation angle, which was significantly different from OA group. The abduction angles were always greater in the G2 and G3 than in the OA group. This might be attributed to a valgus static alignment in G2 and G3 comparing to a varus alignment in the patient with OA.

Conclusions: The newly developed functional knee analyzer provided a non-invasive way to accurately measure 3D kinematic data which enabled cluster analysis to distinguish three gait patterns from 106 healthy subjects. The results suggested a strong correlation between static alignment and dynamic ad-abduction angles during the gait, which need to be investigated. Funding: Other Education Grant Funding Parties: NSERC, CIHR and FCAR

This study evaluated the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis. The pelvic configuration influenced the lumbar lordosis but was not associated with the thoracic kyphosis or with the curve type. The pelvic incidence in adolescent idiopathic scoliosis was higher than that reported in the literature for normal adolescents and was closer to the values of pelvic incidence found in adults. The role of the PI in the pathogenesis of AIS needs to be explored in a comparative study involving AIS patients and normal adolescents.

The purpose of this study was to evaluate the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis (AIS) based on the curve type.

Five sagittal parameters were retrospectively evaluated on lateral radiographs for one hundred and sixty AIS patients: thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT) and pelvic incidence (PI). The patients were classified according to their coronal curve type. ANOVA was used to compare the parameters between the curve types and Pearson’s coefficients were used to investigate the relationship between all parameters.

The TK was significantly lower for King I, II and III curves as compared to lumbar curves. The LL was higher for lumbar curves, although not significantly. No significant change between the groups was observed for SS, PT and PI. The PI was significantly correlated to LL, SS and PT for all groups. The LL was strongly related to the SS in all cases but not with the TK, except for thoracolumbar curves.

The TK mostly depended on the spinal deformity while the LL was mainly influenced by the pelvic configuration. The scoliotic curve type was not associated with a specific pattern of sagittal pelvic configuration. The PI was significantly higher than that reported in the literature for normal adolescents.

The role of the PI in the pathogenesis of AIS needs to be explored in a comparative study involving AIS patients and normal adolescents.

Further study is needed to evaluate the prognostic value of the PI in AIS.

Funding: This research was funded by the Canadian Institute of Health Research.

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