Introduction: Nowdays most of the health services focus on the reduction of expenses and the shorter hospital stay. For the patients is also important the faster rehabilitation in work and in full self-sufficiency.

Patients and methods: Möller has published in 1997, that medial unicompartmental knee arthroplasty can be operated from a shorter mediopatellar approach. This technique is important not only for the shorter wound, but much more for the faster rehabilitation because of the preserve of the extensor mechanism of the knee.

Between April 2000 and December 2002 we performed the minimal invasive medial unicompartmental knee arthroplasty in 36 cases. Our results were evaluated by the HSS knee score. The average follow up time was 24.7 months. We have compared our results to a similar group in age, number and follow up time, who has been operated in the traditional approach.

Results: However the overall HSS results showed significant difference (95.3 & 84.8), we think that the subgroups presents the substance of it much better. There was significant difference in walking distance, stair climbing, range of movement and muscle power, and we did not find any significant difference in pain, transport, flexion contracture, instability, need for appliance and the varus-valgus deformity.

Conclusion: In those cases, where both the patients win with the shorther rehabilitation and also the health service saves money with the reduction of expenses the minimal invasive way of operation should be more often used.

In the past orthopaedic surgeons have kept their hands off from spontaneous or artificial fused hips, because those hips were painless, and the result of any further surgical procedure would be doubtful. In our days the need for conversion hip arthroplasty became a demand of patients having a better quality of life. In this paper we report on our results and the perioperative complications following conversion surgery.

Between 1993 and 2002 thirty-one hips of twentyfive patients (18 males, 7 females) were converted from totally stiff hip to total hip arthroplasty in the two most frequented orthopaedic hospitals in Budapest, Hungary (Semmelweis University, Medical School, Dept. of Orthopaedics & Hospital of Hospitaller Brothers of St.John of God, Dept. of Orthopaedics). The mean age of the patients was 47.2 years (ranging from 14 to 75 years) at the time of surgery. The average follow up was 50.7 months (2–176). At our 25 patients the hips became stiff 15.7 years ago as an average (3–61). Spontaneous fusion occured in 14 cases due to Bechterews disease (spondylitis ankylopoetica). In 4 cases fused hips were converted following arthrodesis procedures. There was no significant difference between each groups, spontaneous ankylosis and surgical fusion were similar, they were evaluated as stiff hips on the same way.

The indication for surgery was in most cases a painful lumbar spine or osteoarthritic knee joint on the ipsilateral side. The surrounding joints are obviously overloaded and overused because of the stiff hip joint, even though if the hip is painless.

27 cemented and 4 uncemented hip prostheses were implanted. The mean duration of conversion arthroplasties was 110 minutes, the perioperative blood loss was 1019 ml. Additional surgical procedures may be used, like intertrochanteric wedge resection, osteotomy of greater trochanter, muscle release from the iliac bone, tenotomy of the hip adductors or knee flexors.

The Harris Hip Score increased significantly from 34.2 to 81.3 (p< 0.01). The leg length discrepancy decreased from 4.0 cm to 1.2 cm, the difference of thigh circumference changed from 4.3 cm to 2.7 cm, all results as an average. Trendelenburgs gait was detected at 25 hips pre-op, and at 5 hips at the time of follow up. Five cases were reoperated due to haematoma formation, there was one prosthesis disclocation and one early septic complication.

Based upon the good clinical results at the follow up, we recommend to change the orthopaedic surgeons’ mind considering conversion arthroplasties. The surgical procedure can be performed securely, but it is technically challenging for each surgeon. The intraoperative use of fluoroscopy and preoperative planning are mandatory in conversion arthroplasty. Conversion arthroplasty is performed prior to severe degenerative changes in the surrounding joints.

Aims: The aim of our work was to measure, the necessary correction angle in unicompartmental knee prosthesis in order to make the patientñs functional result the best following the procedure.

Method: We included all the medial and all the lateral unicompartmental arthroplasties in our department in 1999. For the analysis of the functional results, we have reviewed the patients and recorded the clinical data with the help of the New Jersey Knee Score. We have had the postoperative weight bearing AP knee X-rays also at the same time.

Conclusion: This type of implant can be used with conþdence in medial unicompartmental knee arthroplasties up to 15 degrees of varus deformation preoperatively, according to the early postoperative results. We did not þnd any signiþcant difference in the early functional results between the 10 degrees or less and the more than 10 degrees corrected groups.