Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis

Abstract

Aim: To study a modified porous tantalum technique for the treatment of osteonecrosis of the femoral head.

Methods: The porous tantalum rod was combined with endoscopy, curettage, autologous bone grafting and use of bone marrow aspirates from iliac crest aspiration in 49 patients (58 hips) with a mean age of 38 years. The majority of the patients had idiopathic osteonecrosis, followed by corticosteroid-induced osteonecrosis. Thirty-eight hips were of Steinberg stage II disease and 20 hips were of stage III disease. Patients were followed for 5 years and were evaluated clinically with the Merle D'Aubigne and Postel score and radiologically. The primary outcome of the study was survival based on the conversion to total hip arthroplasty (THA). Secondary outcomes included deterioration of the osteonecrosis to a higher disease stage at 5 years compared to the preoperative period and identification of factors that were associated with survival. The Kaplan-Meier survival analysis was performed to evaluate the survivorship of the prosthesis, and the Fisher exact test was performed to test associations between various parameters with survival.

Results: No patient developed any serious intraoperative or postoperative complication including implant loosening or migration and donor site morbidity. During the 5-year follow up, 1 patient died, 7 patients had disease progression and 4 hips were converted to THA. The 5-year survival based on conversion to THA was 93.1% and the respective rate based on disease progression was 87.9%. Stage II disease was associated with statistically significant better survival rates compared to stage III disease (P = 0.04). The comparison between idiopathic and non-idiopathic osteonecrosis and between steroid-induced and non-steroid-induced osteonecrosis did not showed any statistically significant difference in survival rates. The clinical evaluation revealed statistically significantly improved Merle d'Aubigne scores at 12 mo postoperatively compared to the preoperative period (P < 0.001). The mean preoperative Merle d'Aubigne score was 13.0 (SD: 1.8). The respective score at 12 mo improved to 17.0 (SD: 2.0). The 12-mo mean score was retained at 5 years.

Conclusion: The modified porous tantalum rod technique presented here showed encouraging outcomes. The survival rates based on conversion to THA are the lowest reported in the published literature.

Keywords: Avascular necrosis; Bone grafting; Femoral head; Survival; Tantalum rod.

Figure 1

Endoscopic view of the osteonecrotic lesion. View obtained from the endoscopy through the canal. The posterior aspect of the osteonecrotic lesion is seen at the center of the image (arrow) as a white non-vascularized area, surrounded by normal purple-coloured bone (vascularized bone).

Figure 2

Tantalum rod. The tantalum rod used in the present series, manufactured by Zimmer (Zimmer, Inc, Warsaw, IN, United States). The rod was impregnated with bone marrow aspirates obtained from iliac crest aspiration.

Figure 3

Pre- and post-operative imaging of femoral head osteonecrosis. Imaging of a 42-year-old patient with corticosteroid-induced osteonecrosis of the femoral head treated with porous tantalum. A: Preoperative MRI of Steinberg stage II osteonecrosis of the left femoral head; B: One-year postoperative X-ray after the implantation of the tantalum rod. No pathological findings are seen; C: Five-year postoperative MRI of the left hip with absence of pathological findings. MRI: Magnetic resonance imaging.

Figure 4

Pre- and postoperative X-rays of osteonecrosis of the femoral head. X-rays of a 47-year-old patient with idiopathic osteonecrosis of the femoral head. A: Preoperative X-ray with Steinberg stage II osteonecrosis; B: Six-month postoperative X-ray showing no disease deterioration; C: Five-year postoperative X-ray of the same patient with no pathological findings.

Figure 5

Survival plots for patients with stage II and stage III disease. Within the 5-year follow up period, 4 patients with osteonecrosis treated with tantalum rod were converted to total hip arthroplasty. One patient had Steinberg stage II disease and 3 patients had Steinberg stage III disease. Patients with stage III disease had increased risk to undergo total hip arthroplasty. The difference was statistically significant (P = 0.04).

Figure 6

Conversion of tantalum rod to total hip arthroplasty. A: The osteotomised femoral head with the tantalum rod in a 55-year-old patient who underwent THA due to disease deterioration. The osteotomy of the femoral neck was performed through the tantalum rod; B: Six-week post-THA X-ray of the same patient. The X-ray shows callous formation within the trochanteric hole. THA: Total hip arthroplasty.

Figure 7

Disease progression after tantalum rod implantation. Thirty-eight-year old female patient with osteonecrosis of the left femoral head due to leukemia. A: The immediate postoperative X-ray after the implantation of tantalum rod showing Steinberg stage III osteonecrosis; B: X-ray of the same patient showing deterioration to Steinberg stage IV osteonecrosis 12 mo after the implantation of tantalum rod.