Reliability and Validity of Acetabular and Femoral Bone Loss Classification Systems in Total Hip Arthroplasty: A Systematic Review.

backgroundA variety of classification systems have been developed to help surgeons treat patients with acetabular or femoral bone loss in total hip arthroplasty, yet no "gold standard" for classification has been agreed upon. Furthermore, the reliability and validity of the available classification systems remain unknown. QUESTIONS/PURPOSE: The aims of our study were to determine the reliability and validity of the three most common acetabular and femoral bone loss classification systems (Paprosky, American Academy of Orthopaedic Surgeons [AAOS], and Saleh and Gross).

methodsA systematic review of the literature was performed to identify studies that reported on the reliability or validity (or both) of the acetabular and femoral components of the three bone loss classification systems.

resultsIn all, seven articles met our inclusion criteria. Six studies reported on the reliability (all six studies) or validity (three studies) of acetabular bone loss rating systems (286 acetabula), and five analyzed reliability (all five studies) or validity (three studies) of femoral bone loss classification systems (364 femurs). In studies in which either the Paprosky or AAOS acetabular bone loss classifications were used, the classification systems were considered unreliable in 75% and 100% of them, respectively. On the femoral side, the Paprosky classification demonstrated moderate interobserver and good intraobserver reliability. The AAOS femoral bone classification was found to have good intraobserver reliability but poor interobserver reliability. The Saleh and Gross acetabular and femoral bone loss classification systems yielded mixed results, but each was considered reliable in one of the studies looking at these aspects of the systems.

conclusionAlthough surgical techniques, treatment options, and advanced imaging available to the surgeon have evolved over the past few decades, the acetabular and femoral bone loss classification systems, first developed in the 1990s, have remained largely unchanged. Our results indicate that improvements to these systems are necessary in order for them to be as useful as possible in planning the surgical course.