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.

Introduction: The long-term results of HTO depends on exact reconstruction of the weight bearing line. The lack of exact intraoperative real time control of the mechanical axis often results in postoperative malalignments. After preopertive planing and intraoperative measurement of the deformities, HTO is performed under navigation. The system shows the weight bearing line, the size of the osteotomy wedge and the tibial slope. Aim of the current study is to evaluate accuracy of intraoperative datas using the OrthoPilot in comparison to long standing radiographs including the center of the hip, knee and ankle joint.

Material and method: 54 patients with a mean age 49.7 years underwent HTO with navigation using the Ortho-Pilot. According to Ahlback’s staging 1 patient had I, 4 II, 21 III, 19 IV and 9 V osteoarthritis of the knee.

Results: The mean preoperative deviation of the mechanical axis was 6.0 varus (3 to 14) on the x-ray and was confirmed by the OrthoPilot. The mean postoperative mechanical axis was 1.7 valgus (2 varus to 5 valgus) on the x-ray and was confirmed by the OrthoPilot with 1.4 valgus (0 to 3 valgus). The mean postoperative femorotibial angle was 7.1 (2–11). Complications related to the navigation procedure was one hematoma of the distal pin track.

Conclusion: By using an intraoperative navigation system, the outcome of the preoperative planned procedure becomes more predictable and more precision of the alignment can be achieved in HTO. Long-term studies will have to be carried out to verify whether this will lead to a lasting benefit for the patient.

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.