Minor complications were seen in association with 14 hips (15%), including lateral femoral cutaneous nerve dysesthesia (n = 6), delayed union of the pubis (n = 6), and inferior pubic ramus fracture (n = 2). Regarding reoperation, 3 patients underwent arthroscopy for labral treatment. Two patients who had untreated femoral head asphericity experienced groin pain postoperatively during internal rotation in flexion and underwent femoral neck osteochondroplasty at 3.7 and 5.3 years after periacetabular osteotomy. No patient underwent conversion to total hip arthroplasty during follow-up.
Periacetabular osteotomy is commonly used for the treatment of symptomatic acetabular dysplasia, and clinical outcome studies have indicated that this procedure results in marked pain reduction and functional improvement14 , 24 - 29. However, various factors reportedly have been associated with the outcomes of periacetabular osteotomy9 , 30 - 33. To our knowledge, no previous study has evaluated the effect of femoral and acetabular version on clinical outcomes following periacetabular osteotomy. In the present study, we found that combined femoral and acetabular version after periacetabular osteotomy was significantly correlated with the postoperative ranges of flexion and internal rotation in flexion. However, the degree of femoral version was not independently associated with the clinical outcomes of periacetabular osteotomy when accounting for potential covariates in a general linear model.
Recognition of the interaction between femoral and acetabular morphology is important in clinical practice1 - 3. The concept of combined femoral and acetabular version has been previously reported in studies of pediatric patients with developmental hip dysplasia1, patients who have undergone total hip arthroplasty11, and, recently, patients who have undergone surgery for the treatment of femoroacetabular impingement13. In the present study, we noted significant associations between combined version and flexion as well as internal rotation in flexion in patients who had undergone periacetabular osteotomy. These findings indicate that it may be better to avoid postoperative acetabular retroversion, especially in patients with decreased femoral version. However, acetabular version should not be considered a preferential parameter in acetabular correction. Acetabular dysplasia presents with varying degrees of acetabular version associated with malalignment of the acetabulum. When performing periacetabular osteotomy for reorientation of the acetabulum, surgeons should pay attention to the interaction between femoral and acetabular version as well as the coverage of the acetabulum. For patients with acetabular dysplasia, it is most important that periacetabular osteotomy result in sufficient coverage of the acetabulum rather than increased acetabular version. Taken together, our results further emphasize the importance of recognizing this combined version, even in patients who undergo periacetabular osteotomy for the treatment of acetabular dysplasia.
Decreased femoral version is a distinct dynamic factor that should be considered in the evaluation of mechanical causes of hip pain34. A previous study demonstrated that the range of internal rotation in patients with decreased femoral version was significantly less than that in patients with normal version or increased femoral version both before and after arthroscopic femoral cam decompression (p < 0.05)12. In the present study, we also found a smaller range of internal rotation in hip flexion in the mild femoral version group after periacetabular osteotomy; however, this difference was lost after adjusting for potential covariates. Our results might be because the mild femoral version group had less acetabular version postoperatively than the severe femoral version group. Fabricant et al.13 noted that patients with decreased femoral version had smaller improvements in patient-reported outcomes after arthroscopic surgery for the treatment of femoroacetabular impingement. With the numbers available in the present study, we could not find any significant association between femoral version and clinical outcomes after periacetabular osteotomy. Conversely, excessive femoral anteversion generally can lead to painful restricted external rotation as a result of posterior impingement2 , 34. However, there were no differences in postoperative range of external rotation among the femoral version groups in the present study. Our results indicated that postoperative posterior impingement was less likely to occur in patients undergoing periacetabular osteotomy because the acetabulum was rotated anteriorly through periacetabular osteotomy. Future research is needed to determine the long-term effect of femoral version on several patient-reported outcomes after periacetabular osteotomy.
One advantage of the present study was the large cohort of patients who were evaluated with CT scans after periacetabular osteotomy. Using these postoperative CT scans, we measured postoperative femoral and acetabular version and alpha angle according to previously published methods2 , 19 - 22. In addition, because of the rigorous exclusion criteria in the present study, we could minimize the effect of degenerative change of the hip joint on the CT measurements. To our knowledge, this is the first study to investigate the associations of femoral and acetabular version with clinical outcomes following periacetabular osteotomy. However, the clinical outcomes of periacetabular osteotomy might be affected by further abnormal morphology. Future research is needed to identify such abnormal morphology.
The present study had several limitations. First, few patient-reported outcomes were evaluated. Although patient-reported outcomes are considered the gold standard when evaluating outcomes in a surgical population35, our study included only the modified Harris hip score for clinical scoring. Future research should investigate the effect of femoral and acetabular version on various patient-reported outcomes. Second, the present study lacked evaluation of preoperative acetabular version on CT scans and preoperative range of motion, both of which can affect clinical outcomes. Third, although labral tears are common in patients with acetabular dysplasia, we did not investigate labral pathology in the present study. Because labral pathology also affects clinical outcomes after periacetabular osteotomy36, there might be differences in clinical outcomes depending on the presence of labral tears. Last, there were no patients with femoral retroversion in the present study. A further large cohort study is warranted to investigate the effect of femoral retroversion on outcomes after periacetabular osteotomy.
In conclusion, we believe that ours is the first study to investigate the associations of femoral and acetabular version with clinical outcomes following periacetabular osteotomy. We found significant associations between combined femoral and acetabular version and hip range of motion in patients who underwent periacetabular osteotomy. Our results indicate that patients with decreased combined femoral and acetabular version after periacetabular osteotomy may experience restriction of range of motion. Surgeons performing periacetabular osteotomy should pay attention to postoperative acetabular retroversion as it may result in restriction of range of motion, especially for patients with decreased femoral version. Furthermore, we found that femoral version alone may not affect clinical outcomes after periacetabular osteotomy when adjusting for potential covariates such as the severity of acetabular dysplasia, alpha angle, and acetabular version. It may not be necessary to perform femoral derotational osteotomy routinely at the same time as periacetabular osteotomy unless major femoral retroversion is present. Further research regarding the impact of preoperative acetabular version and preoperative range of motion on the outcomes of periacetabular osteotomy needs to be conducted.
A table showing general linear models for postoperative hip range of motion is available with the online version of this article as a data supplement at jbjs.org (http://links.lww.com/JBJSOA/A45).
Investigation performed at the Department of Orthopaedic Surgery, Fukuoka University, Fukuoka, Japan
Disclosure: There was no external funding for this study. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSOA/A44).
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