Posterior femoroacetabular impingement (PFAI) - after hip resurfacing arthroplasty.

Bulletin of the NYU hospital for joint diseases

PubMedID: 19583549

Ball ST, Schmalzried TP. Posterior femoroacetabular impingement (PFAI) - after hip resurfacing arthroplasty. Bull NYU Hosp Jt Dis. 2009;67(2):173-6.
INTRODUCTION
The recent, encouraging outcome literature on hip resurfacing arthroplasty (HRA) has not sufficiently examined the potential occurrence of postoperative femoroacetabular impingement (PFAI) and sequelae. The current study asks the questions, "Does femoroacetabular impingement occur after hip resurfacing arthroplasty (HRA) and, if so, what are the clinical outcomes?"

METHODS
Sixty-nine consecutive hips in 57 patients with a minimum of 2 years clinical and radiographic follow-up were evaluated. Both acetabular and femoral component positions and postsurgical changes in the femoral neck and acetabulum were recorded.

RESULTS
Fourteen hips in 13 patients (20%) developed a small scalloped, corticated erosion in the posterior neck, just distal to the femoral component and adjacent to the acetabular component rim. These erosions were between 5 and 10 mm in depth and became apparent at an average of 15 months (range, 6 to 24 months) following surgery. After 2 years, they showed no further progression. The location and shape of the erosions indicate PFAI as the etiology. One hip also demonstrated similar changes in the anterior neck. The Harris Hip Score and UCLA (University of California at Los Angeles) Activity Scores were higher in patients with such erosions (97.5 and 9.2, respectively), compared to those patients without (93.5 and 8.4, respectively). Additionally, patients with erosions reported slightly better pain relief on average than patients with no radiographic evidence of impingement. No significant differences in range of motion or component position were found between the two groups.

CONCLUSIONS
Small, corticated, non-progressive erosions can occur from femoroacetabular impingement following HRA. The erosions were more commonly posterior in this series, and they tended to occur in active patients. There is no adverse effect on clinical outcomes, and more specifically, there is no association of PFAI with pain.