Expandable prostheses were designed to allow progressive growth after tumour resection in children. The aim of this study was to report the late results of the non-invasive growing prostheses designed by A Soubeyran (Phenix prosthesis or Wright Repiphysis). From 1994 to January 2006, 27 children aged 4 to 12 (mean 8.5), underwent a resection of the knee for a bone tumour, with reconstruction by a non invasive expandable prosthesis. There were 16 boys and 11 girls. The tumours were 25 osteosarcomas and 2 Ewing tumours. All patients received pre and post-operative chemotherapy. There were 18 distal femur, 7 proximal tibia, and 2 femur + tibia resections. There were different successive designs based on the same electro-magnetic growing mechanism using a pre bent spring, released by eating in an induction coil. After, 7.2 years mean follow-up (4 months to 15 years), 20 patients had no evidence of disease and 7 were deceased. Two with a local recurrence were amputated. Mean lengthening was 5.1 centimeters (0 to 8), after 3 to 11 lengthening procedures. Mean limb-length discrepancy was 1.8 cm. Two patients had a secondary infection. Eleven had a revision for arthrofibrosis. All surviving patients were revised to a conventional hinged prosthesis. The mean MSTS functional score of the definitive prosthesis was 82% (63 to 96%). Theses prostheses showed many mechanical complications as loosening, fracture of the growing mechanism, and arthrofibrosis. The positive outcome was the possibility to perform a progressive lengthening, without surgery limiting the risk of infection. Theses prostheses should be considered as temporary until reconstruction with a conventional hinged prosthesis. Patients with multiple revisions had a tendency to show less favourable late functional results than with primary implanted hinged prosthesis

Aims

The purpose of this retrospective study was to differentiate between the MRI features of normal post-operative change and those of residual or recurrent disease after intralesional treatment of an atypical cartilage tumour (ACT)/grade I chondrosarcoma.

We report our early experience with the use of a non-invasive distal femoral expandable endoprosthesis in seven skeletally immature patients with osteosarcoma of the distal femur. The patients had a mean age of 12.1 years (9 to 15) at the time of surgery. The prosthesis was lengthened at appropriate intervals in outpatient clinics, without anaesthesia, using the principle of electromagnetic induction. The patients were functionally evaluated using the Musculoskeletal Tumour Society scoring system. The mean follow-up was 20.2 months (14 to 30). The prostheses were lengthened by a mean of 25 mm (4.25 to 55) and maintained a mean knee flexion of 110° (100° to 120°). The mean Musculoskeletal Tumour Society score was 68% (11 to 29). Complications developed in two patients; one developed a flexion deformity of 25° at the knee joint, which was subsequently overcome and one died of disseminated disease. The early results from patients treated with this device have been encouraging. The implant avoids multiple surgical procedures, general anaesthesia and assists in maintaining leg-length equality.

We reviewed nine patients at a mean period of 11 years (6 to 16) after curettage and cementing of a giant-cell tumour around the knee to determine if there were any long-term adverse effects on the cartilage. Plain radiography, MRI, delayed gadolinium-enhanced MRI of the cartilage and measurement of the serum level of cartilage oligomeric matrix protein were carried out. The functional outcome was evaluated using the Lysholm knee score.

Each patient was physically active and had returned to their previous occupation. Most participated in recreational sports or exercise.

The mean Lysholm knee score was 92 (83 to 100). Only one patient was found to have cartilage damage adjacent to the cement. This patient had a history of intra-articular fracture and local recurrence, leading to degenerative changes.

Interpretation of the data obtained from delayed gadolinium-enhanced MRI of the cartilage was difficult, with variation in the T1 values which did not correlate with the clinical or radiological findings. We did not find it helpful in the early diagnosis of degeneration of cartilage. We also found no obvious correlation between the serum cartilage oligomeric matrix protein level and the radiological and MR findings, function, time after surgery and the age of the patient.

In summary, we found no evidence that the long-term presence of cement close to the knee joint was associated with the development of degenerative osteoarthritis.