| Objective: Bernese periacetabular osteotomy(PAO)has a good clinical effect on early developmental dysplasia of the hip(DDH).If the indications are not chosen properly,it will not only lead to early failure of PAO,also a great deal of uncertaintiesy about the clinical outcome of subsequent THA procedures.Research purposes: 1.Retrospective analyze the clinical effect and imaging features regarding the patients received THA after acetabular osteotomy,and to summarize the causes of poor postoperative function and prosthesis placement;2.To summarize the characteristics of bone nonunion after PAO,which may affect the postoperative function and pose potential risks to THA subsequently;3.To establish a three-dimensional model of pelvis after periacetabular osteotomy and to investigate the optimal position and angle of acetabular prosthesis in THA after PAO;4.To investigate the influence of acetabular anatomic changes on the stress distribution around the acetabular component after PAO,and to further instruct the placement of the acetabular component in clinical operations to enhance the survivoship of the prostheses.Methods: This study was carried out from four aspects: clinical case analysis,imaging measurement,three-dimensional modeling and finite element analysis.Retrospectively analyze the clinical data of 10 DDH patients,admitted for THA due to hip osteoarthritis or femoral head necrosis following PAO,patients were matched according to age,sex,preoperative Crowe classification and T(?)nnis grade before THA as a control group.Hip function and complications of the two groups were analyzed,the influence of PAO on subsequent THA and the risk factors of postoperative complications were analyzed.2.84patients(84 hips)with PAO were analyzed retrospectively.The incidence of delayed union,nonunion and stress fracture at different follow-up points were analyzed.Risk factors of nonunion and stress fracture around acetabulum were also analyzed.3.28 patients with high risk of postoperative failure were selected to establish three-dimensional pelvic models before and after PAO,and the models were imported into AI-HIP intelligent preoperative planning software to simulate the optimal position of the acetabular cup,we compared the image parameters of acetabular cup position before and after PAO,to study the influence of acetabular prostheses angle change and bone defect introperation.4.Regarding the types of peri-acetabular nonunion determined from the Part 2 study among the above 28 pelvic models,the stress distribution around the acetabular component was analyzed by finite element method before and after PAO.The influence of PAO on the stress distribution around the acetabulum following THA was compared to assess the potential risk of postoperative outcomes and acetabular component failure due to different bone nonunion types.Results: 1.THA after PAO will be with longer operative time,more bleeding.Same survival rate at intermediate follow-up,but Harris score was lower than THA patients who had not received PAO.After PAO,the acetabular rotation center raised,the cup anteversion decreased,the acetabular coverage improved significantly,and the diameter of the acetabular cup implanted was larger than that of the non-PAO patients,residual bone nonunion after PAO was the main reason that affects the curative effect of subsequent THA.2.At least one site nonunion was found in 29.7% PAO patients followed up more than 1year,and 2 cases received THA.Most of the nonunion sites occurred at the superior pubic and without clinical symptoms.Symptomatic stress fractures of the inferior pubic and ischium are often associated with nonunion of the superior pubic ramus,of which the posterior acetabular column nonunion(2%)requires surgical intervention.The correction of LCEA were independent risk factors for nonunion.3.The anterior and medial inferior bone coverage were lower than those of pro-PAO,the lateral coverage of post-PAO were significantly higher than that of pro-PAO,The height of the rotational center raised post PAO,the average diameter of acetabular prostheses after PAO was larger than that of pro-PAO.4.When the simulated acetabular prosthesis was implanted into the acetabulum with 40 ° inclination and 15 ° anteversion,the stress in the pubic ramus increased and the stress in the internal wall was unevenly distributed.PAO had little effect on the stress distribution in the bone tissue above the acetabular cup,but the PAO could increase the stress in the posterior wall of the posterior column caused by the nonunion of the pubis ramus or/and the fracture posterior column of the acetabular,will induce clinical symptoms and affect prosthesis survival rate.Conclusion: 1.Nonunion was the most common complication after PAO.Most of cases don’t need surgical intervention,but ischium and posterior column nonunion often need surgical treatment.2.Patients after PAO need to be fully evaluated for bone defect and acetabular deformity before THA.Previous PAO nonunions may affect follow-up clinical outcomes.THA after PAO should be operated by an experienced surgeon,to reduce operation time and amount of intraoperative bleeding,to avoid raising the hip rotation center,and properly increase the cup anteversion for more bone coverage.3.The stress distribution around the acetabular component obviously changed in the pelvic model after PAO,but the stress shielding around the component was not obvious,bone graft and internal fixation should be considered to apply to,if necessary. |
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