Background: The aim of this prospective multi-center study was to evaluate the clinical and radiological results of a total of 314 uncemented femoral stem revisions using the modular MRP-titanium system.

Methods: 305 patients (111 males, 194 females, mean age 67.7) with 314 MRP-titanium systems were followed-up for a meantime of 3.2 years (1 to 9 years). Pre- and post-operatively all patients were clinically documented using the Harris hip score. Radiologically, the preoperative bony defects were assessed by the Paprosky classification. Post-operatively, periprosthetic bone remodeling was evaluated on the basis of radiographic evidence of bone apposition or resorption.

The modular MRP-titanium system has proven to be valuable in quite problematic cases of hip revision arthroplasty with extensive femoral defects. The system allows intraoperative adaptation of implant length and antetorsion angle to the actual situation, a feature not provided by non-modular femoral revision implants.

Aims: Prospective multi-center study to evaluate the mid-term results of 280 uncemented femoral stem revisions using the modular MRP-Titan system. Methods: 273 patients with 280 MRP-Titan systems, follow-up for a mean time of 3 years (1 to 8 years). Harris hip score for clinical evaluation, bony defect classification according to Paprosky [163 cases (58%) with type 2B, 2C and 3]. Results: Three aseptic loosenings (1%), three septic loosenings (1%), one additional re-revision because of periprosthetic fracture. Postoperative dislocations occurred in 23 cases (8%), 17 of these (6%) were managed by closed or open reposition without changing the implant. In 6 cases (2%) the antetorsion angle of the modular prosthesis neck was altered. Harris hip score: 38 points preoperatively, 85 points at the last follow-up postoperatively. In 18 cases (6.4%) radiolucient lines were seen, but with no progression and no migration of the stems. The overall survival-rate after 8 years of follow-up was 92%. Conclusions: The modular MRP-Titan system has proven to be valuable in quite problematic cases of hip revision arthroplasty with extensive femoral defects. The system allows intraoperative adaptation of implant length and antetorsion angle to the actual situation, a feature not provided by non-modular femoral revision implants.

Introduction.

In rheumatoid arthritis, the forefoot is frequently affected. A variety of surgical procedures have been established in the treatment of rheumatic forefoot disorders. Postoperatively, patients are mobilized in specially designed footwear to reduce forefoot stress. Our study was conducted to investigate peak and mean plantar pressure occurring in two differently designed forefoot relief shoes by using the novel pedar ® system.

Materials and Methods.

Ten symptom-free volunteers were asked to walk on a treatmill, performing two trials at self-selected speed. The ”Barouk” (sole and heel supporting proximal fifty percent of the foot) and “Hannover” (Sole under whole foot, heel supporting proximal fifty percent of the foot) forefoot relief shoe (fior and gentz, Lueneburg, Germany) were compared. In a first trial, the shoe had to be used adequately, while in a second trial, the volunteers tried to put pressure on the forefoot, mimicking non-compliance. Peak and mean plantar pressure were obtained using the pedar® cable system (novel, Munich) and compared to the contralateral foot. Statistical t-test analysis was performed using SPSS 10. 0 for windows™.

Results.

When wearing the “Barouk” shoe with short sole, the forefoot was completely relieved in all trials. Non-compliant use of the shoe did not result in any forefoot stress. At the edge of the sole, peak pressure values were not higher than in conventional footwear. The shoework with complete sole reduced forefoot peak and mean pressure in contrast to normal gait by a mean of 34 percent. However, all volunteers were able to put stress on the forefoot when mimicking non-compliance, reaching peak values similar to normal gait.

Conclusion.

With regard to reconstructive forefoot surgery, the design of forefoot relief shoework affects the safety to non-compliance.