Anterior cervical fusion with tantalum implant: a prospective randomized controlled study

Is anterior cervical fusion with a porous tantalum implant a cost-effective method to treat cervical disc disease with radiculopathy?

STUDY DESIGN

Retrospective cost-effectiveness analysis.

OBJECTIVE

To determine the relative cost-effectiveness of anterior cervical discectomy with fusion (ACDF) using a porous tantalum implant compared with autograft with plating, for single-level cervical disc disease with radiculopathy.

SUMMARY OF BACKGROUND DATA

ACDF with autograft as an interbody spacer is a generally accepted method to treat degenerated cervical discs with radiculopathy. Concerns about donor site morbidity and the structural characteristics of autograft stimulated investigations of alternative materials. Techniques may differ in their operative risks, complications, outcomes, and resource use.

METHODS

A retrospective review of clinical outcomes and total cost of illness for 5 years postsurgery was performed for 61 consecutive patients enrolled for this study. Twenty-eight patients were treated with single-level ACDF using either a stand-alone, porous tantalum implant, without graft inside the implant, and 33 patients received autograft and plating. A cost-effectiveness analysis comparing the 2 ACDF treatment methods was conducted. This article reports clinical assessments, quality adjusted life years gained, and an incremental cost-effectiveness ratio analysis.

RESULTS

Patients in both cohorts reported improved clinical outcomes, including neck disability index, visual analogue scale, Short-Form 36, Odom's clinical assessment, and patient satisfaction at 5 years postindex surgery. The mean cost of illness for the study period, including preoperative through 5 years postoperative assessments, was 6806 per patient treated with tantalum and 10,143 per patient receiving autograft and plate. Quality-adjusted life years (QALY) gained were 9.41 and 7.14 for the tantalum and control cohorts, respectively. The cost per QALY for the tantalum group was 723 and 1420 for the control group. The incremental cost-effectiveness ratio of ACDF with a porous tantalum implant compared with ACDF with autograft and plate was -1473 per patient per year for the duration of this study.

CONCLUSION

This cost-effectiveness analysis reports favorable results for ACDF procedures utilizing a tantalum implant. The data reported suggest that using porous tantalum as a stand-alone device is less costly and more effective than autograft and plate in ACDF procedures.

Comparison of 3 fusion techniques in the treatment of the degenerative cervical spine disease. Is stand-alone autograft really the "gold standard?": prospective study with 2-year follow-up

STUDY DESIGN

A prospective study.

OBJECTIVE

The aim of this study was to compare the 3 different methods of interbody fusion of the cervical spine-autograft in stand-alone technique, autograft with anterior plate, and polyetheretherketone cage supported by anterior plate. The clinical and radiological data obtained were analyzed and discussed.

SUMMARY OF BACKGROUND DATA

Although degenerative cervical spine disease has been treated by an anterior approach for more than 50 years, there is not one generally accepted operative approach. There is a very low-quality evidence of little or no difference in pain relief between each of the techniques. Iliac crest autograft still seems to be the "gold standard" for interbody fusion.

METHODS

Prospective study collecting clinical and radiological data of 81 patients undergoing anterior cervical interbody fusion, in which the interbody fusion of 1 or 2 motion segments from C3 to C7 was done by any of the 3 techniques--stand-alone insertion of autograft (group 1: 28 patients), autograft and anterior plate (group 2: 18 patients), and polyetheretherketone cage filled with beta-tricalcium phosphate and plate (group 3: 29 patients). Patients were followed for 2 years after surgery.

RESULTS

Significant interaction of relative height in the segment and time was found (P < 0.001). The values of the relative height of stand-alone autograft dropped below 95% of initial height and the values of the other 2 groups remained above 105%. Significant interaction of time and group was found for Cobb S angles (P < 0.001). Values of group 1 decreased substantially and remained significantly lower than values of other 2 groups. Fusion rate was 100% in all groups. Neck Disability Index group and time interaction was found (P = 0.023). During postoperative follow-up, group 1 scored in all controls higher than the other 2 groups, but differences were not significant. Visual analogue scale showed effect of time (P < 0.001). This was due to a smaller improvement of patients in group 1 during the whole follow-up in comparison with the other 2 groups. Highest proportion of unsatisfied patients was in group 1 compared with the other 2 groups after 2 years (P = 0.034).

CONCLUSION

Significantly worse radiological and clinical results after 2 years of follow-up were achieved using stand-alone autograft technique in comparison with autograft supported by anterior plating similarly as in comparison with cage implant and anterior plating. Using artificial fusion substrate together with plate and cage can offer the same clinical and radiological results such as iliac autograft and plating. Anterior plating seems to be an important factor influencing the postoperative cervical spine alignment and also the clinical outcome.

Host bone response to polyetheretherketone versus porous tantalum implants for cervical spinal fusion in a goat model

STUDY DESIGN

In vivo assessment of polyetheretherketone (PEEK) and porous tantalum (TM) cervical interbody fusion devices in a goat model.

OBJECTIVE

Directly compare host bone response to PEEK and TM devices used for cervical interbody fusion.

SUMMARY OF BACKGROUND DATA

PEEK devices are widely used for anterior cervical discectomy and fusion but are nonporous and have limited surface area for bone attachment.

METHODS

Twenty-five goats underwent single-level anterior cervical discectomy and fusion and were alternately implanted with TM (n = 13) or PEEK devices (n = 12) for 6, 12, and 26 weeks. Both devices contained a center graft hole (GH), filled with autograft bone from the animal's own iliac crest. The percentage of bone tissue around the implant, percentage of the implant surface in direct apposition with the host bone, and evidence of bone bridging through the implant GH were assessed by using backscattered electron imaging. Bone matrix mineral apposition rate was determined through fluorochrome double labeling, and sections were stained for histological analysis.

RESULTS

The TM-implanted animals had significantly greater volumes of bone tissue at the implant interface than the PEEK animals at all-time points. The TM animals also had a significantly greater average mineral apposition rate in the GH region at 6 and 12 weeks than the PEEK animals. No difference was observed at 26 weeks. A greater number of TM-implanted animals demonstrated connection between the autograft bone and both vertebrae compared with the PEEK implants. Histological staining also showed that the TM devices elicited improved host bone attachment over the PEEK implants.

CONCLUSION

The TM implants supported bone growth into and around the implant margins better than the PEEK devices. TM's open cell porous structure facilitated host bone ingrowth and bone bridging through the device, which could be beneficial for long-term mechanical attachment and support in clinical applications.

Anterior cervical interbody constructs: effect of a repetitive compressive force on the endplate

Graft subsidence following anterior cervical reconstruction can result in the loss of sagittal balance and recurring foraminal stenosis. This study examined the implant-endplate interface using a cyclic fatigue loading protocol in an attempt to model the subsidence seen in vivo. The superior endplate from 30 cervical vertebrae (C3 to T1) were harvested and biomechanically tested in axial compression with one of three implants: Fibular allograft; titanium mesh cage packed with cancellous chips; and trabecular metal. Each construct was cyclically loaded from 50 to 250 N for 10,000 cycles. Nondestructive cyclic loading of the cervical endplate-implant construct resulted in a stiffer construct independent of the type of the interbody implant tested. The trabecular metal construct demonstrated significantly more axial stability and significantly less subsidence in comparison to the titanium mesh construct. Although the allograft construct resulted in more subsidence than the trabecular metal construct, the difference was not significant and no difference was found when comparing axial stability. For all constructs, the majority of the subsidence during the cyclic testing occurred during the first 500 cycles and was followed by a more gradual settling in the remaining 9,500 cycles.

Porous tantalum as a structural graft in foot and ankle surgery

BACKGROUND

Structural bone grafts are often used in foot and ankle surgery to fill gaps, maintain height, length or correction. Bone graft, whether autograft or allograft, has limitations and disadvantages. With porosity and mechanical properties similar to native bone, porous tantalum has been used successfully in hip and knee applications. This study investigates the potential advantages of porous tantalum as a substitute for conventional bone graft in foot and ankle surgery.

METHODS

A retrospective review of 27 arthrodesis procedures was performed of foot and ankle procedures using Trabecular Metal porous tantalum over a period of 5 years. Twenty-five patients were involved. Mean age at the time of surgery was 63 (range, 41 to 80) years. All the patients had pathologies in the foot and ankle that required arthrodesis with structural graft. Average followup was 27 (range, 12 to 72) months.

RESULTS

At final followup the mean American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot/Midfoot score improved from 40.6 (range, 16 to 64) preoperatively to 86.3 (range, 57 to 100) postoperatively (p < 0.001). When the pain component of the AOFAS was examined, the score improved from a mean of 8.2 (range, 0 to 20) to 35.2 (range, 20 to 40), (p < 0.001). At the time of last followup, 56% of patients reported no pain, 40% reported mild occasional pain, and 4% reported moderate pain.

CONCLUSION

Porous tantalum therefore, was found to be a viable alternative to conventional bone graft when structural support was required.

Systematic review of anterior interbody fusion techniques for single- and double-level cervical degenerative disc disease

STUDY DESIGN

A systematic review of randomized controlled trials.

OBJECTIVE

To determine which technique of anterior cervical interbody fusion (ACIF) gives the best outcome in patients with cervical degenerative disc disease.

SUMMARY OF BACKGROUND DATA

The number of surgical techniques for decompression and ACIF as treatment for cervical degenerative disc disease has increased rapidly, but the rationale for the choice between different techniques remains unclear.

METHODS

From a comprehensive search, we selected randomized studies that compared anterior cervical decompression and ACIF techniques, in patients with chronic single- or double-level degenerative disc disease or disc herniation. Risk of bias was assessed using the criteria of the Cochrane back review group.

RESULTS

Thirty-three studies with 2267 patients were included. The major treatments were discectomy alone and addition of an ACIF procedure (graft, cement, cage, and plates). At best, there was very low-quality evidence of little or no difference in pain relief between the techniques. We found moderate quality evidence for few secondary outcomes. Odom's criteria were not different between iliac crest autograft and a metal cage (risk ratio [RR]: 1.11; 95% confidence interval [CI]: 0.99-1.24). Bone graft produced more fusion than discectomy (RR: 0.22; 95% CI: 0.17-0.48). Complication rates were not different between discectomy and iliac crest autograft (RR: 1.56; 95% CI: 0.71-3.43). Low-quality evidence was found that iliac crest autograft results in better fusion than a cage (RR: 1.87; 95% CI: 1.10-3.17); but more complications (RR: 0.33; 95% CI: 0.12-0.92).

CONCLUSION

When fusion of the motion segment is considered to be the working mechanism for pain relief and functional improvement, iliac crest autograft appears to be the golden standard. When ignoring fusion rates and looking at complication rates, a cage as a golden standard has a weak evidence base over iliac crest autograft, but not over discectomy.

Single or double-level anterior interbody fusion techniques for cervical degenerative disc disease

BACKGROUND

The number of surgical techniques for decompression and solid interbody fusion as treatment for cervical spondylosis has increased rapidly, but the rationale for the choice between different techniques remains unclear.

OBJECTIVES

To determine which technique of anterior interbody fusion gives the best clinical and radiological outcomes in patients with single- or double-level degenerative disc disease of the cervical spine.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2009, issue 1), MEDLINE (1966 to May 2009), EMBASE (1980 to May 2009), BIOSIS (2004 to May 2009), and references of selected articles.

SELECTION CRITERIA

Randomised comparative studies that compared anterior cervical decompression and interbody fusion techniques for participants with chronic degenerative disc disease.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed risk of bias using the Cochrane Back Review Group criteria. Data on demographics, intervention details and outcome measures were extracted onto a pre-tested data extraction form.

MAIN RESULTS

Thirty-three small studies ( 2267 patients) compared different fusion techniques. The major treatments were discectomy alone, addition of an interbody fusion procedure (autograft, allograft, cement, or cage), and addition of anterior plates. Eight studies had a low risk of bias. Few studies reported on pain, therefore, at best, there was very low quality evidence of little or no difference in pain relief between the different techniques. We found moderate quality evidence for these secondary outcomes: no statistically significant difference in Odom's criteria between iliac crest autograft and a metal cage (6 studies, RR 1.11 (95% CI 0.99 to1.24)); bone graft produced more effective fusion than discectomy alone (5 studies, RR 0.22 (95% CI 0.17 to 0.48)); no statistically significant difference in complication rates between discectomy alone and iliac crest autograft (7 studies, RR 1.56 (95% CI 0.71 to 3.43)); and low quality evidence that iliac crest autograft results in better fusion than a cage (5 studies, RR 1.87 (95% CI 1.10 to 3.17)); but more complications (7 studies, RR 0.33 (95% CI 0.12 to 0.92)).

AUTHORS' CONCLUSIONS

When the working mechanism for pain relief and functional improvement is fusion of the motion segment, there is low quality evidence that iliac crest autograft appears to be the better technique. When ignoring fusion rates and looking at complication rates, a cage has a weak evidence base over iliac crest autograft, but not over discectomy alone. Future research should compare additional instrumentation such as screws, plates, and cages against discectomy with or without autograft.

Tantalum is a good bone graft substitute in tibial tubercle advancement

BACKGROUND

Porous tantalum is reportedly a good substitute for structural bone graft in several applications. So far, its use has not been reported in tibial tuberosity anteriorization (TTA) for treatment of isolated degenerative chondral lesions of the patellofemoral joint.

QUESTIONS/PURPOSES

We asked whether the use of this material would produce similar standardized functional scores, pain (VAS), fusion rates, complications, and patient satisfaction to those for bone graft.

PATIENTS AND METHODS

We performed a randomized, controlled trial in 101 patients (108 knees) scheduled for TTA comparing a porous tantalum implant (57 knees) with an autologous local tibial bone graft (51 knees). The minimum followup was 5 years (mean, 6.2 years; range, 5-8 years).

RESULTS

At the last followup, clinical scores, fusion rates, and maintenance of the anteriorization either were better or similar for the TTA using the tantalum implant depending on the respective parameter. The operative technique was easier and shorter with the tantalum device. Complication and failure rates were greater using bone graft. Patient satisfaction was greater using the tantalum implant.

CONCLUSIONS

Porous tantalum provided a reasonable alternative to bone graft in TTA.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Anterior cervical discectomy with fusion in patients with cervical disc degeneration: a prospective outcome study of 258 patients (181 fused with autologous bone graft and 77 fused with a PEEK cage)

Background

Anterior cervical discectomy with fusion (ACDF) is challenging with respect to both patient selection and choice of surgical procedure. The aim of this study was to evaluate the clinical outcome of ACDF, with respect to both patient selection and choice of surgical procedure: fusion with an autologous iliac crest graft (AICG) versus fusion with an artificial cage made of polyetheretherketone (PEEK).

Methods

This was a non-randomized prospective single-center outcome study of 258 patients who underwent ACDF for cervical disc degeneration (CDD). Fusion was attained with either tricortical AICG or PEEK cages without additional anterior plating, with treatment selected at surgeon's discretion. Radicular pain, neck-pain, headache and patient satisfaction with the treatment were scored using the visual analogue scale (VAS).

Results

The median age was 47.5 (28.3-82.8) years, and 44% of patients were female. 59% had single-level ACDF, 40% had two level ACDF and 1% had three-level ACDF. Of the patients, 181 were fused with AICG and 77 with a PEEK-cage. After surgery, the patients showed a significant reduction in radicular pain (ΔVAS = 3.05), neck pain (ΔVAS = 2.30) and headache (ΔVAS = 0.55). Six months after surgery, 48% of patients had returned to work: however 24% were still receiving workers' compensation.

Using univariate and multivariate analyses we found that high preoperative pain intensity was significantly associated with a decrease in pain intensity after surgery, for all three pain categories. There were no significant correlations between pain relief and the following patient characteristics: fusion method (AICG or PEEK-cage), sex, age, number of levels fused, disc level fused, previous neck surgery (except for neck pain), previous neck trauma, or preoperative symptom duration. Two hundred out of the 256 (78%) patients evaluated the surgical result as successful. Only 27/256 (11%) classified the surgical result as a failure. Patient satisfaction was significantly associated with pain relief after surgery.

Conclusions

ACDF is an effective treatment for radicular pain in selected patients with CDD after six months follow up.

Because of similar clinical outcomes and lack of donor site morbidity when using PEEK, we now prefer fusion with PEEK cage to AICG.

Lengthy symptom duration was not a negative prognostic marker in our patient population.

The number of patients who returned to work 6 months after surgery was lower than expected.

Can porous tantalum be used to achieve ankle and subtalar arthrodesis?: a pilot study

A structural graft often is needed to fill gaps during reconstructive procedures of the ankle and hindfoot. Autograft, the current gold standard, is limited in availability and configuration and is associated with donor-site morbidity in as much as 48%, whereas the alternative allograft carries risks of disease transmission and collapse. Trabecular metal (tantalum), with a healing rate similar to that of autograft, high stability, and no donor-site morbidity, has been used in surgery of the hip, knee, and spine. However, its use has not been documented in foot and ankle surgery. We retrospectively reviewed nine patients with complex foot and ankle arthrodeses using a tantalum spacer. Minimum followup was 1.9 years (average, 2 years; range, 1.9-2.4 years). Bone ingrowth into the tantalum was analyzed with micro-CT in three of the nine patients. All arthrodeses were fused clinically and radiographically at the 1- and 2 year followups and no complications occurred. The American Orthopaedic Foot and Ankle Society score increased from 32 to 74. The micro-CT showed bony trabeculae growing onto the tantalum. Our data suggest tantalum may be used as a structural graft option for ankle and subtalar arthrodesis. All nine of our patients achieved fusion and had no complications. Using tantalum obviated the need for harvesting of the iliac spine.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Clinical and radiological evaluation of Trabecular Metal and the Smith-Robinson technique in anterior cervical fusion for degenerative disease: a prospective, randomized, controlled study with 2-year follow-up

A prospective, randomized, controlled study was carried out to compare the radiological and clinical outcomes after anterior cervical decompression and fusion (ACDF) with Trabecular Metal (TM) to the traditional Smith-Robinson (SR) procedure with autograft. The clinical results of cervical fusion with autograft from the iliac crest are typically satisfactory, but implications from the donor site are frequently reported. Alternative materials for cervical body interfusion have shown lower fusion rates. Trabecular Metal is a porous tantalum biomaterial with structure and mechanical properties similar to that of trabecular bone and with proven osteoconductivity. As much as 80 consecutive patients planned for ACDF were randomized for fusion with either TM or tricortical autograft from the iliac crest (SR) after discectomy and decompression. Digitized plain radiographic images of 78 (98%) patients were obtained preoperatively and at 2-year follow-up and were subsequently evaluated by two senior radiologists. Fusion/non-fusion was classified by visual evaluation of the A-P and lateral views in forced flexion/extension of the cervical spine and by measuring the mobility between the fused vertebrae. MRI of 20 TM cases at 2 years was successfully used to assess the decompression of the neural structures, but was not helpful in determining fusion/non-fusion. Pain intensity in the neck, arms and pelvis/hip were rated by patients on a visual analog scale (VAS) and neck function was rated using the Neck Disability Index (NDI) the day before surgery and 4, 12 and 24 months postoperatively. Follow-ups at 12 and 24 months were performed by an unbiased observer, when patients also assessed their global outcome. Fusion rate in the SR group was 92%, and in the TM group 69% (P < 0.05). The accuracy of the measurements was calculated to be 2.4 degrees . Operating time was shorter for fusion with TM compared with autograft; mean times were 100 min (SD 18) and 123 min (SD 23), respectively (P = 0.001). The patients' global assessments of their neck and arm symptoms 2 years postoperatively for the TM group were rated as 79% much better or better after fusion with TM and 75% using autograft. Pain scores and NDI scores were significantly improved in both groups when compared with baseline at all follow-ups, except for neck pain at 1 year for the TM group. There was no statistically significant difference in clinical outcomes between fusion techniques or between patients who appeared radiologically fused or non-fused. There was no difference in pelvic/hip pain between patients operated on with or without autograft. In our study, Trabecular Metal showed a lower fusion rate than the Smith-Robinson technique with autograft after single-level anterior cervical fusion without plating. There was no difference in clinical outcomes between the groups. The operative time was shorter with Trabecular Metal implants.

Anterior cervical discectomy: to graft or not to graft?

The debate regarding whether to perform an interbody fusion after anterior cervical discectomy (ACD) has been going on for the last 50 years. Several prospective randomized clinical trials have been performed to evaluate the clinical outcome following anterior cervical discectomy with and without interbody fusion. None of these studies show a significant difference between the two techniques in terms of relief of arm pain or neck pain. The operative time, in-hospital stay and time for return to work seem to be slightly longer following anterior cervical discectomy with interbody grafting (ACDF) compared to ACD alone. However a temporary increase in postoperative axial pain seems to be a common complication following ACD. There is also no difference in the clinical outcomes between ACD and ACDF with plating and ACDF with interbody spacers. However, if a fusion procedure is undertaken, the use of interbody spacers does have the advantage of avoiding donor site complications. There is also some evidence to suggest that plate fixation can lead to increased fusion rates. There is a significant risk of a degree of segmental kyphosis following ACD. These radiological features, however, do not correlate with the clinical outcome. Radiological and clinical studies fail to show a significant difference in recurrence of foraminal narrowing or the rates of reoperation following ACD or ACDF. The available body of evidence suggests that the addition of a fusion procedure following anterior cervical decompression may give improved radiological results but does not necessarily result in improved clinical outcomes.