We developed a three-dimensional finite element model of development dysplasia of hip (DDH) of a patient. And then we performed virtual Bernese periacetabular osteotomy (PAO) by rotating the acetabular bone with different angle so as to increase femoral head coverage and distribute the contact pressure over the cartilage surface. Using finite element analysis method, we analyzed contact area, contact pressure, and von Mises stress in the acetabular cartilage to determine the effect of various rotation angle. We also built a normal hip joint model. Compared to the normal hip joint model, the DDH models showed stress concentration in the acetabular edge, and higher stress values. Compared to the DDH models, the post-PAO models showed decreases in the maximum values of von Mises stress and contact pressure while we increased the contact area. An optimal position could be achieved for the acetabulum that maximizes the contact area while minimizing the contact pressure and von Mises stress in the acetabular cartilage. These would provide theoretical bases to pre-operative planning.
ObjectiveTo investigate the mid-term effectiveness of periacetabular osteotomy (PAO) through modified ilioinguinal approach for acetabular dysplasia in adults. MethodsBetween January 2016 and December 2018, 39 patients (43 hips) with acetabular dysplasia who met the selection criteria were enrolled in the study and their clinical data were retrospectively analyzed. All patients were treated with PAO via modified ilioinguinal approach (firstly, the skin and superficial facia were cut via the traditional ilioinguinal approach, and the deep tissues were cut via the modified iliac-femoral approach). There were 3 males (3 hips) and 36 females (40 hips) with an average age of 36 years (range, 18-51 years). Among them, 35 cases of lesions involved single hip and 4 cases of lesions involved bilateral hips. The disease duration ranged from 4 to 96 months, with a median of 18 months. According to the modified Tönnis grading for osteoarthritis, 35 hips were classified as grade 0, 6 hips as grade Ⅰ, and 2 hips as grade Ⅱ. All patients had different degrees of hip pain. The preoperative visual analogue scale (VAS) score of pain was 4.7±0.8, and the modified Harris hip score was 78.5±8.6. The lateral centre-edge angle (LCEA) was (10.52±10.83)°, and the acetabular index (AI) was (26.89±9.07) °. The operation time, intraoperative blood loss, and the incidence of complications were recorded. LCEA, AI, and the progression of osteoarthritis were reviewed by X-ray films. The function and pain of hip joint were evaluated by modified Harris hip score and VAS score. ResultsAll operations were successfully completed. The operation time was 90-150 minutes, with an average of 130 minutes. The volume of intraoperative blood loss was 350-600 mL, with an average of 500.6 mL. All patients were followed up 17-52 months, with an average of 32.7 months. Postoperative numbness of the lateral femoral cutaneous nerve occurred in 3 cases, and no other complications occurred. At last follow-up, the modified Harris hip score was 97.7±3.7 and VAS score was 0.9±1.1, both of which were better than those before operation (P<0.05). At 1 year after operation, X-ray films showed that the all osteotomies healed. In term of the modified Tönnis grading for osteoarthritis, 1 hip downgraded from grade 1 to grade 0, while the remaining hips stayed unchanged. At last follow-up, LCEA and AI were (27.54±8.49) ° and (11.30±5.53) °, respectively, which were significantly different from those before operation (P<0.05). ConclusionPAO through modified ilioinguinal approach is effective in relieving pain and restoring hip function in adults with acetabular dysplasia, which can overcome the disadvantages of the traditional ilioinguinal approach, and may delay the development of osteoarthritis.
Objective To investigate the effects of femoral offset and mechanical axis of the lower extremity on hip after osteotomy for adult developmental dysplasia of the hip (DDH). Methods A clinical data of 62 adult patients with DDH (62 hips), who underwent periacetabular osteotomy combined with femoral osteotomy between January 2016 and May 2019 and met selective criteria, was retrospectively analyzed. There were 6 males and 56 females. The age ranged from 18 to 38 years, with an average of 24.4 years. Body mass index ranged from 15.8 to 31.8 kg/m2, with an average of 21.8 kg/m2. There were 44 cases of Hartofilakidis typeⅠ and 18 cases of typeⅡ. According to the modified Tönnis osteoarthritis staging, 46 cases were stage 0 and 16 cases were stageⅠ. There were 13 cases with pelvic anteversion, 40 cases with normal pelvis, and 9 cases with pelvic retroversion. Intraoperative blood loss, length of hospital stay, and complications were recorded. Postoperative hip function was evaluated by Harris score and International Hip Outcome Tool (iHOT) score. The femoral offset, collo-diaphyseal angle, hip-knee-ankle angle (HKA), knee valus angle, CE (Wiberg central-edge angle), anterior CE angle, and acetabular index angle were measured and the osteotomy healing was observed on X-ray films. Patients were grouped according to postoperative femoral offset (≥48 mm or <48 mm) and HKA [varus group (HKA<177°), normal group (HKA 177°-183°), and valgus group (HKA>183°)]. Harris score and iHOT score were compared between groups. Results Intraoperative blood loss ranged from 200 to 1 550 mL, with an average of 476 mL. The length of hospital stay ranged from 8 to 21 days, with an average of 13.3 days. All incisions healed by first intention. All patients were followed up 2.0-4.5 years, with an average of 2.8 years. At 1 year after operation, the Harris score and iHOT score of the hip joint significantly increased when compared with those before operation (P<0.05); there were significant differences in the femoral offset, collo-diaphyseal angle, HKA, knee valus angle, CE angle, anterior CE angle, and acetabular index angle between pre- and post-operation (P>0.05). According to the modified Tönnis osteoarthritis staging, 38 cases were stage 0 and 24 cases were stageⅠ; and there was no significant difference between pre- and post-operation (χ2=2.362, P=0.124). There were 11 cases with pelvic anteversion, 38 cases with normal pelvis, and 13 cases with pelvic retroversion, showing no significant difference when compared with that before operation (χ2=0.954, P=0.623). The pubic branch osteotomy did not heal in 9 cases, proximal femur osteotomy did not heal in 2 cases, and inferior pubic ramus stress fracture occurred in 5 cases. There were significant differences (P<0.05) in the Harris score and iHOT score between femoral offset≥48 mm group (n=10) and femoral offset<48 mm group (n=52). There was no significant difference (P>0.05) in Harris score and iHOT score between varus group (n=13), normal group (n=40), and valgus group (n=9). Conclusion Periacetabular osteotomy combined with femoral osteotomy can improve the femoral offset and mechanical axis of the lower extremity of patients with DDH, and improve the functional score of the hip. However, excessive increase of femoral offset during femoral osteotomy is not desirable, resulting in low postoperative functional score.