Der modulare MRP-Titanrevisionsschaft in der Revisionsendoprothetik des H�ftgelenks

[Periprosthetic fractures of the acetabulum and femur : Causes-classification-treatment algorithms]

BACKGROUND

Both increasing implantation numbers of total hip replacements and demographic change with higher populations of older people, indicate that there will be an increase in periprosthetic fractures in the future.

CAUSES

Falls in the home environment are the most common cause. Significant co-factors include reduced patient coordination, reduced bone quality, or implant-associated factors such as local osteolysis or pre-existing implant loosening.

CLASSIFICATION

In the classification of periprosthetic fractures of the femur, the Vancouver classification has prevailed in recent years, which in addition to a description of the localization of the fracture also considers the stability of the prosthesis and bone quality. Based on this, therapeutic algorithms have been developed that can vary from the conservative approach via osteosynthetic options to a replacement of the prosthesis. In order to allow the description of periprosthetic fractures on all joints, the Vancouver classification has been extended to the UCS classification by including the AO/OTA bone and joint coding system. In the selection of the treatment method, the consideration of individual patient factors such as activity level and secondary diagnoses is essential. Based on the established classifications, the importance of the different therapeutic methods is presented.

Mid term results with the curved modular tapered, fluted titanium Revitan stem in revision hip replacement

We report our experience of revision total hip replacement (THR) using the Revitan curved modular titanium fluted revision stem in patients with a full spectrum of proximal femoral defects. A total of 112 patients (116 revisions) with a mean age of 73.4 years (39 to 90) were included in the study. The mean follow-up was 7.5 years (5.3 to 9.1). A total of 12 patients (12 hips) died but their data were included in the survival analysis, and four patients (4 hips) were lost to follow-up. The clinical outcome, proximal bone regeneration and subsidence were assessed for 101 hips. The mean Harris Hip Score was 88.2 (45.8 to 100) after five years and there was an increase of the mean Barnett and Nordin-Score, a measure of the proximal bone regeneration, of 20.8 (-3.1 to 52.7). Five stems had to be revised (4.3%), three (2.9%) showed subsidence, five (4.3%) a dislocation and two of 85 aseptic revisions (2.3%) a periprosthetic infection. At the latest follow-up, the survival with revision of the stem as the endpoint was 95.7% (95% confidence interval 91.9% to 99.4%) and with aseptic loosening as the endpoint, was 100%. Peri-prosthetic fractures were not observed. We report excellent results with respect to subsidence, the risk of fracture, and loosening after femoral revision using a modular curved revision stem with distal cone-in-cone fixation. A successful outcome depends on careful pre-operative planning and the use of a transfemoral approach when the anatomy is distorted or a fracture is imminent, or residual cement or a partially-secured existing stem cannot be removed. The shortest appropriate stem should, in our opinion, be used and secured with > 3 cm fixation at the femoral isthmus, and distal interlocking screws should be used for additional stability when this goal cannot be realised.

[Revision hip stems: an analysis of the fixation]

BACKGROUND

Revision hip replacements are complicated surgeries because the femoral quality is often reduced by large substance losses. Stem fixation in terms of sufficient primary stability is therefore a great challenge for the orthopaedic surgeon.

AIM

The aim of the present study was to examine two currently used prostheses in Germany (MHP and MRP) concerning their ability to securely bridge femoral defects.

RESULTS

Up to a segmental metaphyseal defect, both stems showed sufficient fixation in our experimental setup. However, because of its predominantly distal fixation, the MRP stem would unnecessarily bridge proximal bone areas still capable of load bearing. In the presence of a transfemoral approach, the surgeon should favour the distal fixation mode because in this situation the proximal fixation option is absent. Therefore, the isthmus takes a key role for both stem designs.

[Periprosthetic fractures after total hip arthroplasty : classification, diagnosis and therapy strategies]

The number of periprosthetic fractures following hip replacement is increasing due to longer life expectancy and the rising number of joint replacements. The main causes of periprosthetic fractures include trauma, implant specific factors or loosening of the endoprosthesis. When planning therapy, surgeons should consider specific and general implant- and patient-related risk factors to ensure the best possible treatment. Established classification systems can facilitate preoperative planning. At present, the Vancouver classification system probably comes closest to the ideal, as it considers fracture configuration, stability of the implant and quality of the bone stock. Depending on these factors, therapeutic options include conservative treatment, fracture stabilisation or replacement of the endoprosthesis. The problems associated with periprosthetic fractures of varying etiology and the available treatment options are discussed against the background of the established classification systems.

[Replacement of femoral hip prostheses]

Femoral revision of total hip arthroplasty is a technically demanding procedure. Therefore, accurate preoperative planning is essential for good clinical results. With many reconstruction methods available, the decision-making process can be complex. Well established classification systems can facilitate preoperative planning. At the time of revision surgery appropriate implants and instruments have to be available ensuring the possibility of managing operative complications. Primary goals of revision arthroplasty are restoration of the physiological joint biomechanics and primary stable fixation of the revision implant. In consideration of possible repeat revision surgery, cementless stem fixation should be preferred. Modular stems provide significant flexibility in restoring the center of rotation. Depending on the pre-existing femoral defect, osseous grafts can be necessary.The scope and classification systems of femoral osseous defects in revision arthroplasty will be discussed and different treatment options will be outlined, which guide the surgeon in selecting an appropriate method of reconstruction.

High medium-term survival of Zweymüller SLR-plus stem used in femoral revision

Revision after failed THA resulting from loosening of the femoral component can be challenging even for experienced surgeons. Aseptic loosening usually is associated with some degree of bone loss. We asked whether the Zweymüller SLR-Plus((R)), along with allograft reconstruction of the deficient femoral bone stock, would provide survivorship, osseointegration, and stability similar to or better than previously reported implants for femoral revision. We retrospectively reviewed 69 selected patients (70 hips) who underwent revision of the femoral component using the SLR-Plus((R)) stem during a 10-year period. The indications for revision included aseptic and septic failure of biologic fixation, incorrect implantation, and periprosthetic fracture. Seven patients died and four were lost to followup. Fifty-eight of the 69 patients (59 hips) were available at a mean 8.3 +/- 2.7 years (range, 4-14 years) after revision surgery. There were 14 men and 44 women (mean age, 69 years; range, 42-89 years). Four stems (7%) were rerevised. With rerevision for aseptic reasons, the survival at 10 years was 95% (95% confidence interval, 86%-98%). No femoral periprosthetic osteolysis occurred around the stem and 91% of stems appeared stable radiographically (osseointegration, fibrous). Based on the survival data, we believe the SLR-Plus((R)) stems are reliable for patients undergoing hip revision surgery with central bone loss.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.