Limb-length measurement in total hip arthroplasty using a calipers dual pin retractor

Limb-length inequality is not uncommon after total hip arthroplasty (THA) and may cause subjective problems for patients. During THA a stable reference point must be established to determine changes in leg length. Several methods have been useful in minimizing the incidence and magnitude of this problem. The equalization of leg-length discrepancy during THA can be achieved through the use of a simple measuring device, the calipers dual pin retractor (CDPR).

The CDPR was developed to establish a fixed point on the pelvis that would remain constant throughout the procedure and from which the distance to the greater trochanter could be measured prior to dislocation of the hip. Limb lengths were measured in 56 patients undergoing primary THA, between 2004 and 2006. The CDPR was used in all cases.

The preoperative diagnoses were osteoarthritis in 44 patients, osteonecrosis in five, and rheumatoid arthritis in seven. Average postoperative limb-length inequality was 4.2 mm. None of the patients had to use shoe lifts for equalization of limb lengths or complained of limb-length inequality.

This method of measurement is beneficial with most THA approaches, and the technique is helpful for minimizing limb-length inequality during THA.