Periacetabular osteotomy is an effective way to rebuild the acetabular structure, relief the pain after movement and improve the movement function of the hip. In general, patients whose age ranges from ten years to fifty years, that showed a reduced pain and normal movement function of the hip, a healed acetabular callus line, a good relationship between the head and the acetabular and a none or mild osteoarthritis are proper indication for PAO. On the contrary, if a patient was much younger or older, or with poor movement function of hip, or poor relationship between the head and the acetabular, or serious osteoarthritis, the outcome of PAO is poor, and therefore its application is counter indicated [16]. Recently, the ilioinguinal, the Smith-Petersen, and the minimally invasive transsartorial approached were usually used to perform the periacetabular osteotomy surgery; that is a new and relatively safe approach, with minimally invasive transsartorial that can reduce surgical trauma, blood loss, and the duration of surgery. Although more orthopedists consider the minimally invasive transsartorial approach safer than other approaches, it is difficult to perform PAO surgery since the incision is relatively smaller. However, there are some studies that compare the outcome between the among ilioinguinal, the Smith-Petersen, and the minimally invasive transsartorial approaches [17-20].
In adult developmental dysplasia of the hip, the abnormal femoral head and acetabular structure, the hip range-of-motion containing flexion, extension, external rotation, internal rotation, abduction, adduction, are inconsistent in normal people. For example, the degree of extension and internal rotation is larger than the normal value, even it is hard to correct to normal degree after rotational acetabular osteotomy (RAO) or periacetabular osteotomy (PAO) surgery [21-22]. In our study, the hip range-of-motion is a huge discrepancy in healthy people, as the degree of abduction motion is smaller and the degree of adduction motion is obviously larger than in healthy people.
In patients with DDH, as the acetabular dysplasia and the total femoral coverage are lower, with the femoral head leading to shift toward and above the acetabulum leading to luxation and hip instability. It is difficult to determine the center of the hip since the abnormal structure of hip; it may cause a little deviation when we measure the angle on an image map especially with the lateral center-edge and the anterior center-edge angles [23]. Meanwhile, most patients with DDH have bilateral leg length discrepancy leading that leads to pelvic tilt, that affects the limitless of the technology of taking image maps, causes interference and influences the measuring of angles and indexes of the hip, finally leading to the deviation of results analysis by drawing inaccurate conclusions [24]. In the post-PAO surgery image map, the anatomical sign of acetabular is not obvious or difficult to determine. Radiographic data, in both group modified S-P and group I-I, may result into errors, that influence the final results of the analysis. In our study, we invited three researchers to analyze the radiographic data, and in case of inconsistent results, we discussed the results until drawing same conclusions, or if the disagreement persisted, we seeked advise from senior doctors.
Comparing to total hip arthroplasty, periacetabular osteotomy surgery has a higher incidence of complications. As in the front and rear of the acetabular are respectively found the femoral nerve and the sciatic never, PAO surgery is more inclined to injure the nerve and blood vessels that surround the acetabular causing abnormal motion and feeling. The pelvis has a rich blood supply and PAO has a large damage range that can cause interoperation blood loss in most patients, and which would require blood transfusion to restore blood volume. At the same time, acetabular coverage may be incomplete or excessive leading to unsatisfactory function recovery if no sufficient preparation during pre-operation [25-27]. In our study, as the incision was long and deep using the ilioinguinal approach, the patient easily acquires an incisional infection; while the surrounding nerve may be pulled by the modified Smith-Petersen approach due to the relatively small incision.
Although periacetabular osteotomy was used to cure adult developmental dysplasia of the hip for many years, the best approach to use among the ilioinguinal, the Smith-Petersen and the minimally invasive transsartorial approaches is unclear. In our study, we draw a conclusion that there is no significant difference in the improvement of the function of hip at post-operation, but group I-I may take more operation time and more loss of blood in intra-operation. However, there are still several limits. Firstly, this paper is a retrospective study, with many factors that may interfere with the results of the analysis; secondly, the number of patients is smaller, and therefore there is a need to increase the sample size; and finally, our study is a single center study, and we need several hospitals to join the study in order to draw a more accurate conclusion in the future.
In conclusion, the periacetabular osteotomy is an effective way to correct adult developmental dysplasia of the hip, whether using the modified Smith-Petersen (S-P) or the ilioinguinal (I-I) approaches. There is no significant difference in the improvement of the function of the hip at post-operation, but group I-I may take more operation time and loss of blood in intra-operation.