Proper cup positioning is a critical component in the success of total hip arthroplasty surgery. A multicenter study has been initiated to study a new type of highly cross-linked polyethylene. This study provides a unique opportunity to a review the acetabular cup placement of over 500 patients implanted in the past 2 years from 13 medical centers from the U.S., Mexico, and Europe. 482 patients have received primary total hip arthroplasty using components from a single manufacturer in 5 centers in the US and Mexico and 7 centers in Europe. The acetabular anteversion and inclination were measured in post-operative radiographs. An acceptable window of cup position is defined at 5–25° of anteversion and 30–45° of inclination.Introduction
Methods
We implemented an exhaustive operative and supervision algorithm for surgical treatment of hip fractures primarily based on own previously published literature. The purpose was to improve supervision and reduce the rate of reoperations. 2000 consecutive unselected patients above 50 years admitted with a hip fracture were included, 1000 of these prospectively after implementation of the algorithm. Demographic parameters, hospital treatment and reoperations within the first postoperative year were assessed from patient records. The algorithm dictated the surgical treatment based on three objective patient parameters: age, new mobility score and fracture classification on pre-operative anterior-posterior and axial radiographs. Intra capsular fractures were treated with two parallel implants, a sliding hip screw, an arthroplasty or resection of the femoral head. Extra capsular fractures were treated with a sliding hip screw or an intramedullary nail. Supervision of junior registrars was mandatory for the prosthesis and intramedullary nail procedures.Introduction
Materials and methods
At 70 patients the femur was augmented (mesh, cerclage(s) and/or plate). A short stem (115–135mm) was used in 48% and a long stem (165–225mm) in 52% of the cases.
Postoperative the femoral stem had a varus position (6 –10°) in 4 cases. In 6 cases the stem was in posterior and 3 cases in anterior position. Progressive subsidence was demonstrated in 1 patient increasing to 5 mm at 1 year fu. Three patients showed subsidence of 3 mm at 3 months, but were stable afterwards. Slightly increasing radiolucent lines (>
2 mm) were noticed in 2 patients in subcortical areas, but never any signs of osteolysis. Intra- and postoperative femoral fractures occurred in 12 patients (13,6%). There were 3 dislocations and 1 loosening of a trochanteric osteotomy. Despite the fractures there was no loosening of a stem during follow-up period. After bivariate multilevel analysis, conducted to determine a relationship between the fracture complication and all other variables, a multivariate model was developed of the most significant variables to determine the predictor factors for femoral fracture. Only the Endo-classification and age are predictors for a fracture following a RIG procedure (p-value 0.003). Each higher EC type increases the probability of a fracture after RIG 2.01 times and each added year of life 1.07 times. So the risk of getting a femoral fracture increases exponentially with age from 1.7% at 55 years to 15.5% at 90 years in EC type 1. The fracture risk in EC type 4 increases from 4.7% at 40 years to almost 60% at 90 years.
During the operative procedure, the lateral femoral wall was fractured in 6% (9/158) of patients, in which an IMHS was performed versus 28% (42/153) operated with a DHS (p<
0.001). Among the DHS, a fractured lateral femoral wall was confirmed to be a predictor of a reoperation (31% (13/42) of patients with a fractured lateral femoral wall versus 8% (9/111) with an intact lateral femoral wall, p<
0.001). As in other studies, the different reoperation rate would have been overseen in the main group of AO/ OTA type 31A1-2 PTF fractures (4% (6/164) IMHS versus 6% (30/471) DHS, p=0.196).
After implementing the guideline, the rate of unsupervised junior registrars performing operations declined from 20% (188/938) to 6% (21/336, p<
0.001 X2). The rate of reoperations declined from 15% (139/938) to 10% (35/336, p=0.044 X2, p=0.043 log.reg.), with a 20% (85/436) to 13% (23/174) decline for intracapsulary and an 11% (54/502) to 7% (12/162) decline for extracapsulary fractures.