| Objective:To study the effect of the Jumbo acetabular cup on the rotation center,femoral offset and biomechanics in the treatment of acetabular bone defects in revision hip arthroplasty.Methods:The retrospective study included patients from August 2015 to November 2018.(1)There were 35 patients(36 hips)in which the Jumbo cup was used to treat the acetabular bone defects in revision hip arthroplasty,including 21 males and 14 females,whose average age was 60.89±10.34 years old.The primary unilateral revision was performed on 31 patients,while the other three were secondary unilateral revisions,and one patient was primary bilateral revision.For the reasons of acetabular revisions,there were 33 hip revisions caused by aseptic loosening,and 3 revisions caused by infection after primary total hip replacement.According to the Paprosky acetabular defect classification,there were 5 hips of type Ⅱ A,8 hips of type Ⅱ B,6 hips of type Ⅱ C,and 17 hips of type Ⅲ A.Among them,31 hips were treated with Jumbo cup(56mm-68mm),and 5 hips were treated with Jumbo cup and metal augments,combining with bone graft or fixed by screws when it is necessary.(2)A total of 6 cases were treated with non-Jumbo acetabular cup combined with metal augments,including 1 male case and 5 female cases,with an average age of 63.67±9.44 years old,and the acetabular bone defects were all type Ⅲ A.Postoperative follow-up includes:(1)The Harris hip score was used to evaluate the clinical efficacy after revision hip arthroplasty,the Visual Analogue Score was used to evaluate the clinical efficacy of hip revision,and the complications such as dislocation or infection were observed;(2)bilateral hip radiographs were taken to observe the cup position,bone condition around the Jumbo cup and the bone graft healing.According to the radiographs,measure the rotation center,femoral offset and abductor arm of the hip joint after revision surgery,and evaluate the effect on the clinical efficacy and biomechanics of hip revision surgery.Results:(1)All the patients were followed up for a mean period of 20.25±10.56 months(range:4-43 months).The average post-operation Harris score at the last follow-up was 86.07±6.71,significantly different from pre-operation in statistic(t=-29.78,P<0.05),and the average post-operation VAS score at the last follow-up was 0.17±0.38,significantly different from pre-operation in statistic(t=16.02,P<0.01).Only 1 postoperative dislocation occurred,the dislocation rate is 2.78%.No complications such as infection,rejection and nerve damage appeared.(2)In Paprosky IIIA type cases,the sizes of the Jumbo cup were smaller in the cases in which the metal augments were used for revision than in the cases in which the metal augments were not used,and the difference in the sizes of the Jumbo cup was statistically significant(t=6.881,P<0.05).(3)The height of hip rotation center was significantly different from the other side in statistic(t=6.881,P<0.05).The average hip rotation center elevation was 11.88±10.36mm,and the Jumbo cup position resulted in an average hip rotation center elevation of 4.49±9.35mm.the size of Jumbo cup resulted in an average hip rotation center elevation of 7.39±6.20mm.There was a significant linear regression relationship in statistic(F=360.00,P<0.01)between the hip rotation center elevation caused by Jumbo cups and the Jumbo size.By using metal augments,the degree of the hip rotation center elevation caused by acetabular cups could be reduced(t=-2.454,p<0.05).(4)After revisions,the difference of femoral offset between both sides was statistically significant(t=2.567,p<0.05).There was a positive correlation between the femoral offset and the abductor ann on the revision side(r=0.412,P<0.05)Conclusions:In revision hip arthroplasties,the clinical results of Jumbo cups for acetabular defect were excellent.There were many advantages including the short operative time and the quick postoperative recovery.But the Jumbo cups could lead to the hip rotation center elevation,and the elevation was affected by the position and the size of Jumbo cups.The application of metal augments could reduce the size of the acetabular cups and the hip rotation center elevation caused by acetabular cups.The increase of femoral offset can prolong abductor arm and improve the hip function. |
