Purpose: One of the biomechanical objectives of total knee arthroplasty (TKA) is to achieve a mechanical femorotibial axis of 180°. Frontal angulation greater or equal to 7° is a factor of poor implant survival. The development of computer-assisted navigation systems has led to the discovery of new concepts: dynamic goniometry, quantitative evaluation of ligament balance. The purpose of this study was to evaluate the influence of the rotational position of the femoral implant and its variation during flexion.

Material and methods: We reviewed the files of 50 patients who underwent surgery between October 2001 and December 2002 for computer-assisted implantation (Orthopilot(r)). We studied femorotibial axis at 0°, 30°, 60° and 90° before the bone cuts, after the tibial cuts and at the end of the procedure after definitive fixing of the implants.

Results: The population, mean age 70 years, was evenly distributed: 17 valgum and 32 varum. The mean femorotibial axis at the end of the operation with the definitive implants in place was 0° in extension with balanced ligaments (±2°) and more often increased varus at 30°, 60° and 90° flexion.

Discussion: External rotation of the femoral piece was not systematic. Certain normally aligned knees in extension after the tibial cut presented significant varus in flexion, probably due to external rotation of the femoral epiphysis. On the contrary, knees with internal rotation of the femoral epiphysis, irrespective of the cause, showed a trend to valgus during flexion. Using external rotation of the femoral implant systematically for both knee morphotypes cannot be done without deteriorating the ligament balance in certain patients.

Conclusion: The advent of navigation systems for TKA has led to the discovery of new concepts such as dynamic goniometry. This has enabled study of femorotibial alignment in flexion, the working position of the knee during walking. This study showed that systematic external rotation of the femoral implant for TKA is not appropriate for all patients.

Purpose: A prospective multicentric study was conducted in a concentric and consecutive series of 204 patients operated on between Mai 1999 and August 2001 for fracture of the proximal femur. The purpose of this study was to assess quality of life after surgery in patients undergoing implantation of the Intermedia® prosthesis.

Material and methods: Mean patient age was 79.6± 8.6 years), 18.8% men. Most of the fractures were Garden III and IV fractures (87.4%) and 90.9% were recent (< 21 d). The intermediary Intermedia® prosthesis was implanted via the posterolateral approach in 73.9% of the patients with acetabular preparation in 13.7%; a head with a restraining skirt was used in 20.8%. The Robinson score for motion, lifestyle, degree of osteoporosis (Singh score), history (ASA), psychomotor index (Hodkinson score) were determined preoperatively (19/26 (±6.89). The Merle d’Aubigné score was calculated at one year. Adaptation of the femoal stem (3 sizes) to the shaft was assessed on standard x-rays. The Kobayashi method was used to study stem to shaft fit; this score gives a rate of shaft filling used to determine whether the self-blocking contact was well achieved with the three stem sizes available.

Results: There were eleven (5.4%) posterior dislocations including four which were reduced orthopaedically. Among the 203 patients, 40 (19.7%) were lost to follow-up and 34 died. The Merle d’Aubigné score at one year showed 84.7% satisfactory results (excellent, very good, good). Preoperatively 59% of the patients were independent and 7% resided in nursing homes, these figures at one year were 55.5% and 5% respectively. Radiologically, the rate of migration (impaction) was 3.9% at one year. Stem-to-shaft fit was, according to Kobayashi for the proximal, middle, and distal portions 73%, 75% and 75% respectively.

Discussion: Mortality due to fracture of the proximal femur is high (16.7% at one year). Morbidity was due to infection (1%) and eleven displacements (5.4%). The difference in motion and lifestyle between the pre- and postoperative period was not significant. Simplification of the implantation procedure by using three stem sizes did not produce any radiological differences at one year.