Comparison of heterotopic bone after anterolateral, transtrochanteric, and posterior approaches for total hip arthroplasty.

The effects of anterolateral, transtrochanteric, and posterior surgical approaches for total hip arthroplasty on heterotopic bone formation were studied in 507 consecutive patients with osteoarthritis or avascular necrosis who had not had previous hip surgery. Range of motion, degree of pain, and satisfaction were compared. Although the lowest incidence of ectopic ossification occurred after the posterior approach, there were no statistically significant differences among the three approaches. Extensive ectopic bone, involving more than half the distance between the trochanter and acetabulum, occurred in 29% after anterolateral, 28% after lateral transtrochanteric, and 22% after posterior approaches. Motion was most affected by the lateral approach, whereas relief of pain and general satisfaction were slightly better with the posterior approach. Multivariate statistical analysis suggests that the difference in results (p less than 0.05) with the posterior approach is primarily due to a relatively lower incidence of severe grades of heterotopic bone.