Comparison of two reinforcement rings for primary total hip arthroplasty addressing displaced acetabular fractures: a biomechanical analysis.

INTRODUCTION: Aim of this study was to biomechanically compare two different acetabular cup fixation constructs in terms of fracture fixation for displaced acetabular fractures involving the anterior column with hemitransverse fracture under partial and full weight-bearing conditions. METHODS: Two different reinforcement rings designed as cages for primary THA were biomechanically tested in terms of managing a complex acetabular fracture. Single-leg stance cyclic loading was performed to assess fracture gap movement and fragment rotation. Twelve hemi pelvis Sawbones were divided into two groups: primary THA with acetabulum roof reinforcement plate (ARRP) (n = 6) and primary THA with Burch-Schneider reinforcement cage (BSRC) (n = 6). RESULTS: During loading under partial weight-bearing (250 N) fracture gap movement tended to be larger in the BSRC group as compared to the ARRP group. Under full weight-bearing conditions, the ARRP showed 60% significantly less motion (p = 0.035) of the os ilium to os ischii gap compared to BSRC. Fracture gap movements between the os ilium and spina iliaca fragments were significantly reduced by 76% (p = 0.048) for ARRP in contrast to BSRC. The ARRP group also demonstrated significantly less movement in the fracture gaps os ischii to quadrilateral plate (62% reduction, p = 0.009) and quadrilateral plate to spina iliaca (87% reduction, p < 0.001). Significantly less rotational movement of the quadrilateral plate to the os ilium was exhibited by the ARRP group (p = 0.015). CONCLUSIONS: The presented acetabulum roof-reinforcement plate (ARRP) provides stable conditions at the acetabular component with adequate stabilization of a displaced acetabular fracture.

Revision of type III and type IVB acetabular defects with Burch-Schneider anti-Protrusio cages.

Extensive bone loss in severe acetabular deficiencies can make repair with acetabular shells impossible. We retrospectively analyzed mid-term to long-term results of acetabular revision with Burch-Schneider reinforcement cages in 33 hips in patients with a mean age of 59.03years after a mean follow-up period of 6.19years. Under the American Academy of Orthopaedic Surgeons classification, 9 patients had type III acetabular bone defects and 24 had type IVB. Merle D'Aubigné scores improved by a mean of 9.3 points. The prosthesis failure rate was 15.1%, the series complication rate was 21.2%, and the mean survivorship was 11.57years. The Burch-Schneider cage is useful for reconstruction in massive acetabular deficiency, but complication rates are high and long-term mechanical failure is a concern.

Comparison of the Accuracy of 2D and 3D Templating for Revision Total Hip Replacement.

INTRODUCTION: Revision hip arthroplasty is a challenging surgical procedure, especially in cases of advanced acetabular bone loss. Accurate preoperative planning can prevent complications such as periprosthetic fractures or aseptic loosening. To date, the accuracy of three-dimensional (3D) versus two-dimensional (2D) templating has been evaluated only in primary hip and knee arthroplasty. METHODS: We retrospectively investigated the accuracy of 3D personalized planning of reinforcement cages (Burch Schneider) in 27 patients who underwent revision hip arthroplasty. Personalized 3D modeling and positioning of the reinforcement cages were performed using computed tomography (CT) of the pelvis of each patient and 3D templates of the implant. To evaluate accuracy, the sizes of the reinforcement cages planned in 2D and 3D were compared with the sizes of the finally implanted cages. Factors that may potentially influence planning accuracy such as gender and body mass index (BMI) were analyzed. RESULTS: There was a significant difference (p = 0.003) in the accuracy of correct size prediction between personalized 3D templating and 2D templating. Personalized 3D templating predicted the exact size of the reinforcement cage in 96.3% of the patients, while the exact size was predicted in only 55.6% by 2D templating. Regarding gender and BMI, no statistically significant differences in planning accuracy either for 2D or 3D templating were observed. CONCLUSION: Personalized 3D planning of revision hip arthroplasty using Burch Schneider reinforcement cages leads to greater accuracy in the prediction of the required size of implants than conventional 2D templating.