Distal Femoral Endoprosthesis Research Articles

A knee-sparing distal femoral endoprosthesis using hydroxyapatite-coated extracortical plates

We used a knee-sparing distal femoral endoprosthesis in young patients with malignant bone tumours of the distal femur in whom it was possible to resect the tumour and to preserve the distal femoral condyles. The proximal shaft of the endoprosthesis had a coated hydroxyapatite collar, while the distal end had hydroxyapatite-coated extracortical plates to secure it to the small residual femoral condylar fragment. We reviewed the preliminary results of this endoprosthesis in eight patients with primary bone tumours of the distal femur. Their mean age at surgery was 17.years (14 to 21). The mean follow-up was 24 months (20 to 31). At final follow-up the mean flexion at the knee was 102 degrees (20 degrees to 120 degrees) and the mean Musculoskeletal Tumour Society score was 80% (57% to 96.7%). There was excellent osteointegration at the prosthesis-proximal bone interface with formation of new bone around the hydroxyapatite collar. The prosthesis allowed preservation of the knee and achieved a good functional result. Formation of new bone and remodelling at the interface make the implant more secure. Further follow-up is required to determine the long-term structural integrity of the prosthesis.

Periprosthetic Bone Remodeling Around a Prosthesis for Distal Femoral Tumors: Longitudinal Follow-up

Serial measurements using dual-energy x-ray absorptiometry (DEXA) were undertaken to evaluate progressive periprosthetic bone loss in patients treated for primary bone tumors of the distal femur using an uncemented tumor prosthesis. Twelve patients underwent sequential DEXA analysis on average 26.5 and 90.9 months postsurgery. Changes in bone mineral density were measured in regions of interest (ROIs) around the prosthesis stem. The test-retest reliability coefficient ( r) ranged from 0.92 to 0.99 for all ROI. In the most distal ROI (ROI1), 10 of 11 patients with 2 measurements showed no change or a small increase in absolute bone mineral density. The results in other ROIs were similar. This longitudinal DEXA data suggest that progressive bone resorption is not problematic with an uncemented distal femur endoprosthesis at intermediate follow-up.

Osteosarcoma occurring in osteogenesis imperfecta tarda

The combination of osteogenesis imperfecta (OI) and osteosarcoma is rare, as reflected by the fact that there are only eight proven cases in the published English literature. We present here another case, one that was treated by modern oncological techniques and major limb salvage surgery in the form of distal femur endoprosthesis initially and later a total femur replacement. The patient is the only one of the series to have had major limb salvage and is the only--and longest--surviving patient (more than 6 years), thus disproving the probability that this combination of disorders is particularly lethal. We present the case history, review the literature, and look at the cases presented in the past. We contend that adequate awareness, early diagnosis, and prompt oncological management results in better prognosis for osteosarcoma occurring in OI.

Tibial turn-up for long distal femoral bone loss.

Since 1990, seven patients have been treated by the authors with the tibial turn-up procedure. They have ranged in age from 8 to 37 years; four were skeletally mature adults and three were children. All seven patients were faced with a clinical situation that required surgical removal of a long portion of their affected distal femur. Three of the adult patients initially were treated for osteosarcoma with long distal femoral resections and allograft arthrodesis of the knee. The allografts ultimately failed, two because of aseptic failure and one because of infection. One patient required distal femoral removal for chronic osteomyelitis and pathologic fracture. Of the three children who were treated, two had turn-ups after long resection of the distal femur for bone malignancy, and one had a secondary turn-up after failure of a long distal femoral endoprosthesis. The technique uses the normal ipsilateral tibia as a vascularized pedicle graft to restore femoral length. The ultimate result, even after very high above knee resection, is a long above knee amputation stump. The followup of the patients in the current study ranged from 2 to 8 years. All patients achieved healing and were able to wear above knee prostheses. The tibial turn-up is an effective procedure that results in a long functional above knee amputation stump even after very high above knee resections.

Limb salvage surgery for primary bone sarcoma of the lower extremities: long-term consequences of endoprosthetic reconstructions.

Adjuvant chemotherapy and endoprosthetic replacement for bone sarcomas of the lower extremity is well established. The specific long-term consequences of these endoprosthetic reconstructions for the patient's affected limb are unknown. The oncologic results and the survival of the endoprostheses were reviewed in 32 patients with primary bone sarcoma of the femur or proximal tibia. There were 26 high-grade sarcomas, and 6 low-grade sarcomas. A proximal femoral endoprosthesis was used for reconstruction in 4 patients, a total or push-through femoral endoprosthesis in 11 patients, a distal femoral endoprosthesis in 15 patients, and a proximal tibial endoprosthesis in two patients. Median survival was 10 years (range, 1.1 to 18.9 years) for patients with high-grade sarcoma, and 8.1 years (range, 7.1 to 10 years) for patients with low-grade sarcomas. Distant metastases developed in seven patients (22%), all with stage IIB sarcoma, with concomitant local recurrence in 3 patients (9%). Five-year overall and disease-free survival rates for high-grade sarcomas were 81% and 73%, respectively. The overall endoprosthetic survival rate was 87% at 5 years, 80% at 10 years, and 56% at 15 years. Median follow-up of the original endoprostheses was 8.3 years (range, 0.6 to 18.7 years). Endoprosthesis-related complications occurred in 13 patients (41%); most complications were mechanical failures. The highest complication rate was found in distal femoral replacements (60%); amputation was necessary in both patients treated with a proximal tibial endoprosthesis. Five endoprostheses (16%) were revised. An amputation of the involved limb was performed in four patients (13%): in two patients because of local recurrence and in the other two patients because of infection. For patients alive at follow-up, the median functional Enneking evaluation score was 22 points (range, 12 to 28 points), with the highest functional scores in patients with a distal femoral endoprosthesis, and the lowest functional scores in patients with total or push-through femoral replacements. Endoprosthetic reconstructions gave satisfying functional results in most patients after long-term survival. However, the proximal tibial and distal femoral endoprosthesis are particularly at risk for long-term endoprosthetic complications requiring additional surgical procedures.