Does the posterior surface of the femoral head maintain its sphericity in patients with end-stage osteoarthritis?

Purpose The aim of this study was to assess whether the posterior surface of the femoral head (FH) has relatively less cartilage wear compared to other surfaces. Methods 75 FHs were studied from patients undergoing total hip arthroplasty (THA). Articular cartilage was stained using Indian ink. Firstly, FHs were assessed to identify the main area of full-thickness cartilage loss. Secondly, the relative proportion of full-thickness cartilage loss on each FH surface was quantitively assessed using a custom MATLAB program. Results Only 7% of FHs had predominantly either posterior or posterosuperior wear. The posterior surface of the FH had 56% less cartilage loss than the superior surface and 49% less cartilage loss than the anterior surface (P < 0.01). Conclusion The posterior surface of the FH is well-preserved in osteoarthritis and may be exploited using intra-operative navigation techniques to aid accurate location of FH centre when performing THA via the posterior approach.