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

One hundred and forty eight hybrid total hip arthroplasties in patients less than seventy years old were randomised to metal on polyethylene or alumina on alumina bearing surfaces. At two to seven years of follow-up, no significant difference was found on hip scores or survivorship of the implants. No specific complication associated to alumina components like fracture or malpositionning of the acetabular insert were observed. Alumina on alumina bearing surfaces give early clinical and radiological results similar to metal on polyethylene, suggesting that they have a potential to become good bearing surfaces in hip arthroplasty for young patients.

The excellent results obtained with metal-polyethylene (M-P) bearing surfaces in total hip arthroplasty (THA) are still limited by the production of polyethylene wear debris, osteolysis and aseptic loosening. Because of it superior tribologic properties and bioinert composition, alumina-alumina (AL-AL) bearing surfaces are proposed to improve survival of THA but previously reported early complications prevented widespread use of alumina ceramic. This study compares early results and complication with Ceraver M-P and AL-AL THA.

One hundred forty-eight Ceraver hybrid THA in patients less than seventy years old were randomised to M-P or AL-AL bearing surfaces. We present the clinical and radiological results for patients two to seven years after their surgery.

No significant difference was found on W.O.M.A.C. and Merle D’Aubigné Postel scores. No specific complication associated with alumina components like fracture or malpositionning of the acetabular insert were observed in this study. Documented complications were: infection 4 AL-AL/2 M-P; dislocation 1 AL-AL/4 M-P; and heterotopic ossification 47% AL-AL/24% M-P. No aseptic loosening was observed.

Ceraver AL-AL bearing surfaces give early clinical and radiological results similar to M-P. Our results are in accordance with studies suggesting that AL-AL have a potential to become good bearing surfaces in THA in the young patients.

Funding: funding was obtained from Ceraver, Paris to perform this study.

Introduction and Aims: Vertical acetabular cup positioning is an important technical aspect in total hip arthroplasty. It has been reported that acetabular component malpositioning is associated with an increased risk of dislocation, limited range of motion and impingement. A high vertical acetabular angle is correlated positively with premature polyethylene wear, osteolysis and early aseptic loosening in metal-polyethylene and ceramic-ceramic interface.

Method: To evaluate the potential benefit of using an inclinometer in vertical acetabular cup positioning, 96 patients were randomised to have their acetabular cup insertions done with an inclinometer or by visuo-spatial perception alone. The surgeries were performed by five hip surgeons.

Results: The precision of the acetabular vertical angles averaged 43 degrees +/-6.7 by visuo-spatial perception alone and 44 degrees +/-6.8 with the inclinometer. With the inclinometer and by visuo-spatial perception respectively, 12.8% and 9.3% of the cups were outside a safe angle range of 35–54 degrees. The standard deviation was +/-4.9 degrees for the inclinometer and +/-4.7 degrees for the visuo spatial perception method.

Conclusion: The use of an inclinometer is as precise as the visuo spatial perception of a hip surgeon. Positioning the cup with the inclinometer did not reduce the variability or improve the precision of the vertical acetabular position during total hip arthroplasty, suggesting it is not an essential adjunct in the clinical practice of hip surgeons. However, the inclinometer might be a valuable tool for surgeons performing a low volume of hip surgery.

Introduction and Aims: Because of its superior tribologic properties and bioinert composition, alumina-alumina (AL-AL) bearing surfaces are proposed to improved survival of total hip arthroplasty (THA), but previously reported early complications prevented widespread use of this material. This study compares early results and complication with Ceraver Metal-Polyethylene (M-P) and AL-AL THA.

Method: One hundred forty-eight Ceraver hybrid THA in patients less than 70 years old were randomised to M-P or AL-AL bearing surfaces. We present the clinical and radiological results for patients two to seven years after their surgery.

Results: No significant difference was found on WOMAC and Merle D’Aubigné Postel scores. No specific complication associated with alumina components like fracture or malpositioning of the acetabular insert were observed in this study. Documented complications were: infection four AL-AL /two M-P; dislocation one AL-AL /four M-P; and heterotopic ossification 47% AL-AL /24% M-P. No aseptic loosening was observed.

Conclusion: Ceraver AL-AL bearing surfaces give early clinical and radiological results similar to M-P. Our results are in accordance with studies suggesting that AL-AL have a potential to become good bearing surfaces in THA in the young patients.

Aims: It was the aim of the present study to evaluate the resulting 3D kinematics following different surgical techniques of reconstruction in a combined posterior cruciate ligament (PCL)/posterolateral structures (PLS) injury model. Methods: In nine human cadaveric knees, 3D kinematics were recorded during the path of ßexion-extension using a computer based method. Additional laxity tests were conducted at 30¡ and 90¡ of ßexion. Testing was performed before and after cutting the PLS and PCL, followed by PCL reconstruction alone. Reconstructing the posterolateral corner, three surgical techniques were compared: 1) biceps tenodesis (BT), 2) posterolateral corner sling procedure (PLCS), and 3) bone patellar-tendon bone allograft reconstruction (BPTB). Results: Posterior as well as rotational laxity were closely restored to intact values by all tested procedures. Compared to the intact knee, 3D kinematics revealed signiþcant internal tibial rotation for 1) BT (mean = 3.9¡, p = 0.043) and for 3) BPTB allograft (mean = 4.3¡, p = 0.012). 2) PLCS demonstrated a tendency to internal tibial rotation between 0¡ and 60¡ of ßexion (mean = 2.2¡, p = 0.079). Varus/valgus rotation as well as anterior/posterior translation did not show signiþcant differences for any of the tested techniques. Conclusion: The present study showed that despite satisfying results in static laxity testing, pathological 3D knee kinematics were not restored to normal, demonstrated by a non-physiological internal tibial rotation during the path of ßexion-extension.