Purpose of the study: Revision total knee arthroplasty (rTKA) is becoming a routine procedure. The technical problems are greater than with a first-intention implantation because of the potential malposition of the initial implants, loss of bone stock, and prior ligament injury. It could be hypothesised that as for implantation of a primary TKA, navigation might improve the quality of the implantation.

Material and methods: We used the Orthopilot™ (Aesculap, RFA) navigation system for first-intention TKA. The standard software was used for revisions. The acquisition of the anatomic and kinematic data was performed while the initial implants in situ. The implants were then removed. Any bone recuts required were done under navigation control. The size of the implants and their thickness were determined after digital simulation of residual laxity; ligament balance was adapted from this data. The system does not allow navigation for centromedullary stem extensions nor for filling potential bone defects. Sixty patients underwent the procedure. There was a comparative series of 30 patients who underwent manual conventional revision using an instrumentation guided by the centromedullary femoral and tibial stems. The quality of the implantation was determined by measuring the alignment of the limb and the orientation of the implants on the postoperative x-rays. Outcome was analysed with Student’s t test and the chi-square test with p< 0.05 taken as significant.

Results: There was a significant improvement in quality of the implantation for all radiographic criteria in the navigation group. Limb alignment was restored in 88% of the navigated cases and 73% of the conventional cases. Similar differences were observed for femoral and tibial implant position on the lateral and AP views.

Discussion: The objectives set for implant orientation and ligament balance can be met with the navigation system for the majority of knees, with a rate similar to that achieved with primary implantation. The navigation system is an appreciable aid for these often difficult procedures where visual information can be misleading.

Conclusion: The navigation system used here facilitated revision TKA.

Purpose: Use of autologous chondrocyte grafts for the treatment of knee cartilage damage appears to be a promising solution. We report preliminary retrospective results in 15 autologous chondrocyte grafts with maximum 4.1 years follow-up.

Material and methods: From September 1996 to December 2000, 15 autologous chondrocyte grafts were performed in 15 patients (13 men and two women), mean age 29.1 years (14.2–46.5) using the Carticel procedure of the Genzyme Tissue Repair laboratory. There were ten trauma-induced chondral lesions and five cases of osteochondritis dessicans. The lesions were located in the femoral condyles in 14 cases (12 medial and two lateral) and the patella in one. Mean surface defect was 6 cm2 (1–15) and all lesions were ICRS grade 3 or 4. The technique described by Brittberg et al. was used. Harvested cartilage was sent to Cam-bridge (USA) for culture. Reimplantation, performed by arthrotomy in all cases, was achieved 12 weeks on average (3.5–29) after initiating culture. Clinical and laboratory results at last follow-up were compared with preoperative data using the ICRS evaluation chart and the Tegner, IKDC, modified Cincinnati, and Lysholm scores. Patients were followed regularly with x-rays, MRI or arthroscan.

Results: Mean follow-up was 2.5 years (1.2–4.1). The subjective IKDC, modified Cincinnati, and Lysholm scores progressed respectively from 38.3 (9–46) to 71.3 (24–98), from 31.6 (18–69) to 58.4 (26–97) and from 41.9 (13–61) to 81.3 (29–100). According to this classification, outcome was excellent or good in ten knees, fair in four and poor in one. For the activity level assessed by the ICRS and Tegner classifications, scores declined respectively from 2.2 (1–3) and 7.4 (5–10) preoperatively to 2.8 (2–4) and 5.2 (2–7) at last follow-up.

Discussion: Due to the small number of patients, it is difficult to compare our results with those reported in the literature. Clinical and functional improvement appeared to be significant but in our experience, there was a decline in the mean sports level at last follow-up.

Conclusion: Autologous chondrocyte grafting appears to be a promising technique for repairing cartilage damage. Use of second-generation grafts with chondrocytes embedded in a solid matrix should facilitate their surgical implantation and improve outcome.