Clinical experience with porous tantalum cervical interbody implants in a prospective randomized controlled trial

Abstract

A prospective randomized study was undertaken to evaluate the radiological appearance and clinical effectiveness of two porous tantalum (Hedrocel) implants in achieving a stable cervical interbody fusion. A prerandomization protocol was used to allocate patients to the three arms of the study: a ring implant containing autologous cancellous bone graft, a solid block implant or autologous tricortical iliac crest bone graft. Patients were followed for 2 years with plain radiological studies, SF-36, and Neck Disability Index questionnaires and neurological assessment. Early in the study the postoperative radiographs of four patients receiving Hedrocel implants showed inferior end-plate lucency raising concerns about delayed or non-fusion. Recruitment to the study was halted by the investigators to allow longer-term follow-up of the implanted patients when only 24 patients had been recruited to the study. Although fusion was subsequently noted in all patients at 12 months there was no further enrolment to the study. At 2 years the radiological and clinical outcomes of the three groups appeared comparable, but the study numbers were too small for any statistical analysis. This study highlights the difficulties that can arise when clinical caution takes precedence over objective measures of clinical progress during a study. In the absence of an independent safety monitoring committee, the investigators were under an ethical obligation to suspend recruitment to this study, until it was clear that the radiological features were not associated with poor clinical outcomes. The use of safety monitoring committees and the clarification of stopping criteria in relation to outcome measures should be considered in open randomized trials of spinal surgical techniques and implants.

Can Porous Tantalum Be Used to Achieve Ankle and Subtalar Arthrodesis?: A Pilot Study

“…trial period before exposing more patients, despite the fact that porous tantalum already was used in spinal surgery. A similar situation was reported by Wigfield et al when starting to use tantalum in spine surgery [54]. Second, the imaging of tantalum by CT or micro-CT is associated with artifacts in the tantalum and in the direction of the xray beam [28,51].…”

“…Tantalum has been used successfully in cervical interbody fusions and primary and revision total hip and knee replacements [19,20,30,36,37,40,46,47,54]. Its use in foot and ankle surgery has not been documented.…”

“…First, the number of patients was small and conclusions comparing tantalum with autograft or allograft are not possible. A randomized controlled prospective trial would be needed [19,54]. A larger series of 50 to 100 patients originally was planned with approval from the authors' local institution, but our plans subsequently were modified by the Provincial Health Technology Assessment Committee to include a limited number of patients who would be reviewed after a short Fig.…”

“…Harvesting autograft at the iliac crest has a reported donorsite morbidity rate of 15% to 48% (postoperative hematoma, infection, hypesthesia, increased postoperative pain, wound dehiscence, cosmetic defect, prolonged pain in the long term, and impairment in ambulation, work, and activities of daily living [17,21,24,38,42]). The cost of tantalum (approximately $1000 per block in the US) is comparable to allograft ($850, plus approximately [3,4,56] Similar to gold standard [19,54] Difficult radiographic assessment of fusion [28,51,54] No donor-site morbidity, no reported complications [19,20,36,37,54] Unlimited Approximately $1000 per piece 5 minutes of preparation time in the operating theater) or harvesting iliac crest autograft (estimated at $600 to $700, as it involves approximately 20 minutes of operating time, suture material, sponges, and dressing) ( Table 1). The treatment of a failed total ankle replacement is challenging with only a few reports of outcomes (Table 2).…”

“…In two randomized controlled trials comparing tricortical autologous iliac crest graft and porous tantalum, similar clinical (SF-36, neck disability index, visual analog scale) and radiographic outcomes were found at 2 years. However, tantalum was associated with a lower complication rate than autograft as it avoided any donor-site morbidity [19,54]. Tantalum also has been used successfully in primary and revision THAs and TKAs for reconstruction of large bony defects [20,30,36,37,40,46,47] and as a possible intervention for osteonecrosis of the femoral head [15].…”