Medium-Term Outcome of Periacetabular Osteotomy and Predictors of Conversion to Total Hip Replacement

Abstract

Periacetabular osteotomy can be performed with a good outcome at medium-term follow-up, suggesting that it may be applied by experienced surgeons with satisfactory results. To further improve the outcome, focus should be on the potential negative influence of parameters that are easily assessed, such as the preoperative grade of osteoarthritis, the presence of an os acetabuli, and severe acetabular dysplasia.

What Factors Predict Improvements in Outcomes Scores and Reoperations After the Bernese Periacetabular Osteotomy?

“…PAO can be used to perform reliable correction of deformity with predictable improvements in center-edge angle, Tönnis angle, and alpha angle. These results are consistent with the other studies in which the consensus is that PAO is a reliable technique for correction of adult hip dysplasia [16,27]. Interestingly, we found a higher alpha angle to be associated with a lower postoperative WOMAC score.…”

“…Given that 60% of patients undergoing PAO have evidence of cartilage damage on arthroscopy [22], there may be a role for perioperative hip arthroscopy to address intraarticular pathology, particularly in patients with higher preoperative alpha angles. Patients who underwent PAO for hip dysplasia in this high-volume subspecialty setting had excellent survivorship and improvements in functional scores; this is consistent with other studies that evaluated some of those same endpoints [1,15,27]. PAO can be used to perform reliable correction of deformity with predictable improvements in center-edge angle, Tönnis angle, and alpha angle.…”

“…First, all operations were performed in a single center by a single surgeon, which may affect the generalizability of our results. However, given that our surgical protocol and study population are similar to others found in the literature [15,24,27], our results may be representative, at least for highvolume subspecialty hip-preservation practices. Second, our study was a retrospective case series with no control.…”

“…These included Tönnis angle (median, 15.3°; range, 0°-55°), minimum joint space width (median, 5 mm; range, 1-45 mm), center-edge angle [30] (median, 16.5°; range, 224°to 28°), presence of crossover sign (32.4%), and alpha angle [21,25] (median, 52.8°; range, 29°-82°), with 57% of hips (41 of 72) having an alpha angle greater than 50.5°. Medial translation of the hip center was measured based on methods described previously by Clohisy et al [6] and Troelsen et al [27] as the difference between the horizontal distance from the most medial aspect of the femoral head to the ipsilateral ilioischial line measured on AP radiograph pre and post-PAO (median, 1.4 mm; range 24.5 to 8.7 mm). Presence of osteoarthritis was assessed by the Tönnis grade [26]: no osteoarthritis (Grade 0); increased sclerosis of the head and acetabulum (Grade 1); small cysts in the femoral head or acetabulum, increased narrowing of joint space, and moderate loss of femoral head sphericity (Grade 2); large cysts in the head or acetabulum, severe joint space narrowing or obliteration, severe deformity of the femoral head; and or evidence of necrosis (Grade 3).…”

“…This reorientation medializes the joint center and reduces superolateral inclination, thus improving femoral head coverage [7,14]. Although recent studies have focused on assessing the medium-and longterm outcomes of PAO [10,11,15,24,27], neither the level of patient function nor the factors that influence clinical and functional outcome are well described [10,11,15,24,27] for an invasive procedure with a risk of major complications ranging from 6% to 37% [7].…”