Implants with multidirectional locked screws have theoretical advantages in the treatment of periprosthetic fractures. In osteoporotic bone those locked plate systems with multidirectional applicable screws give a high stability. With the possibility of fixing screws in various angles, a rigid fixation in the presence of a prosthetic implant can be achieved. We concluded a retrospective study of a consecutive series of the outcome of Vancouver B1 and C femoral injuries using two specific locked implants (Straight and wave plate).

From June 1996 to December 2004 we treated 58 patients with a periprosthetic fracture of the femur with a locked plate. The mean age at the index procedure was 72.4 years, 40 patients were female (69%). In 32 cases (55.2%) we saw a hip endoprosthesis, in 21 cases (36.2%) a knee endoprosthesis and in 5 cases both (8.6%). Outcome measures were intra- and postoperative complications, bony union, degree of mobility and social status, Barthel mobility index and “stand up and go” test.

Union occurred in 56 cases (96.5%) after the index procedure. Twice the implant failed, we saw 4 general complications. The mean duration until full weight bearing status in these patients was 8.6 weeks.

At follow up 46 patients (78%) had maintained the same social status as before the fracture. Regarding the mobility status 52 patients (89%) had regained their previous level, 4 patients walking without aid before now required a cane and two patients a walking frame. The mean Barthel Index was 85 points of possible 100 and improved from 35 points at point of beginning of the rehabilitation. The mean stand-up& go time was measured as 22 seconds.

Conclusion: Overall failure rates of osteosynthesis after periprosthetic fractures of up to 35% are reported (20). With 3.5% implant related failures and 7% general complications, the presented Methods: achieve bony union and mobility in a high percentage of cases.

Fully automated robots for the planning and implantation of total hip arthroplasty have completely withdrawn from the market. Reasons were technical problems during the reaming process that lead to postoperative neurological problems. This lead, especially in Germany, to numerous court cases and created a hostile environment regarding robotic orthopaedic surgery.

The first steps in the development of a robotic assisted system for total hip arthroplasty are presented. This system will be able to plan and mill both femoral and acetabular implant seat. This project aims to combine the advantages of minimally invasive techniques and navigational systems with the accuracy that robotic assisted bone milling can provide. One of the main goals is the study of the technical problems of previous systems and to develop methods to prevent those.

The project-name is RomEo (Robotic minimally invasive Endoprosthetics), the main project partners are the Helmut-Schmidt University/Hamburg and the Department of Trauma and Orthopaedics of the BG Trauma Hospital Hamburg. The paper focuses on:

The determination of forces acting on the femur during milling: The determination of the ideal minimally invasive access route in cadaver operations

The “workspace” created in minimally invasive hip surgery as determined in cadaver operations, including a 3D reconstruction

Possible solutions of the problems of non-invasive patient fixation as determined in cadaver testing with different fixation methods

Feasibility of 3D operation simulation using Voxelman data, access route data and implant CAD data