A new approach for the Martell 3‐D method of measuring polyethylene wear without requiring the cross‐table lateral films

Due to the uneven and often inadequate quality of cross‐table lateral hip radiographs, many radiographic studies of femoral head penetration into polyethylene in total hip arthroplasty are limited to the two‐dimensional measurement of femoral head penetration using the A/P film only. We postulated that the use of two oblique frontal projections at 90° to each other would improve the three‐dimensional evaluation. Using an established hip phantom, the idealized accuracy and precision of the three‐dimensional Martell method was evaluated, contrasting the standard A/P and cross‐table lateral projections versus a pair of oblique projections by four independent readers.

Accuracy and precision resulting from the use of two oblique projections (average accuracy ±63 μm, precision ±26 μm) were similar to that obtained using the conventional A/P and cross‐table lateral views (accuracy ±54 μm, precision ±22 μm), though the results of the two oblique views were slightly more variable. These observations suggest that by using two oblique A/P projections, the major disadvantage of using the cross‐table lateral films, namely the variable quality of the images, is avoided. Perhaps, therefore, the utility and availability of three‐dimensional data in comparable clinical studies may be improved.