A COMPARISON OF MECHANICAL JIG AND COMPUTER NAVIGATED TOTAL HIP RESURFACING

Abstract

With the advent of the advancement of manufacturing technologies hip resurfacing (HR) has become a serious option for a younger patient with osteoarthritis of the hip. The operation is technically demanding and correct placement of the femoral component is the critical step.

We hypothesised that with computer navigation we can improve the placement of the femoral component and restore the biomechanics of the hip joint compared to currently available mechanical jigs.

We compared the radiological results and operation time in 8 patients undergoing computer navigated hip resurfacings (cnHR) to 30 patients undergoing mechanical jig hip resurfacings (jigHR).

Our results showed the average angle of the central pin in the femoral neck in the jigHR group was 141 degrees on the AP radiographs (range 131 to 154 degrees) and 6 degrees antevertion (range 0 to 8 degrees) on the lateral radiographs compared with 135 degrees (range 134 to 138 degrees)and 5 degrees (range 3 to 8 degrees)in the cnHR group. The position of the central pin in the neck immediately below the head was off-centre in the jigHR group on average by 4mm in both AP and lateral radiographs and never more than 2mm in the cnHR group in either view. Offset was increased on average 5mm in the jigHR group and decreased on average by 3mm in the cnHR group. The average operation time was 107 minutes in the jigHR group and 110 minutes in the cnHR group.

We conclude that despite our relatively small sample group we have showed computer navigation gives consistent optimum positioning of the femoral component and improves the biomechanics of the hip. This was without increasing operating time.