Lumbar Fusion versus Total Disc Arthroplasty for Mechanical Low Back Pain

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Chapter 234 Lumbar Fusion versus Total Disc Arthroplasty for Mechanical Low Back Pain

Fusion

Low back pain is so common a condition that most adults are familiar with its symptoms. The majority of patients suffer from the acute or subacute varieties of low back pain and require only minimal intervention. However, about 5% to 10% of patients develop chronic low back pain.1 A substantial body of literature suggests that the outer layers of the lumbar intervertebral disc are the primary tissue involved in mechanical low back pain.24 It has been suggested that either abnormal motion or an excessive biomechanical load in the degenerative disc segment results in pain symptoms. Hence, the elimination of these factors by fusion of the affected spinal segment might eliminate pain when nonsurgical treatment has failed to provide sufficient relief.

Although lumbar fusion remains the standard of care for the management of chronic low back pain, the clinical results are quite variable. Most recently, several artificial disc prostheses have become available. These new implants are intuitively attractive alternatives to fusion, as they theoretically (1) provide more consistent or greater improvement of symptoms and function and allow for faster recovery and return to work and daily activities, (2) maintain or restore motion at affected lumbar segment, and (3) decrease the incidence of adjacent-level disease.

A critical appraisal of currently available data is performed here. Although several theoretical advantages of total disc replacement (TDR) over fusion have been proposed, a significant question remains whether these advantages are clinically relevant and applicable.

Fusion Is a Simpler and More Predictable Operation than Total Disc Replacement

If a patient has failed nonsurgical treatment and a diagnostic workup warrants surgery, lumbar fusion has a single goal: to eliminate motion at the affected segment. If the fusion is solid and the patient continues to have pain, the pain is obviously not originating from the fused motion segment. In other words, the surgeon’s rationale for performing the operation was not correct. Recent evidence suggests that motion-sparing procedures are more challenging than fusion.510 Implant design, size, precise positioning, status of facet joints, and other variables play significant roles in the outcome of the procedure. In fact, the current literature suggests that the majority of implant-related complications are due to a poor choice of size or position of the implant.11,12 Although current implants are better than their predecessors, they are far from optimal. Mikeal et al. showed that current implants do not fit 98% of the patients. Huang et al. studied the prevalence of contraindications to TDR in a cohort of lumbar surgical patients.13 The authors reviewed 100 consecutive patients who had lumbar surgery carried out by one surgeon in 2002. Contraindications to TDR included central or lateral recess stenosis, facet joint arthrosis, spondylolysis or spondylolisthesis, herniated nucleus pulposus with radiculopathy, scoliosis, osteoporosis, postsurgical pseudarthrosis, or deficiency of the dorsal elements. Patients were divided into fusion or nonfusion groups, and the percentage of patients without contraindications to TDR was calculated. Out of 100 patients, 56 underwent spine fusion and 44 underwent nonfusion surgery. In the fusion group, 56 of 56 (100%) patients had contraindications to TDR. In the nonfusion group, 11% (5 of 44) were considered candidates for TDR. Overall, 5% of patients were considered candidates for TDR. The average number of contraindications to TDR was 2.48 (range, 0–5).

Total Disc Replacement Does Not Provide Greater Improvement of Symptoms and Function

Blumenthal et al. reported the outcomes of the first randomized control trial comparing Charité TDR and ALIF with the BAK cage filled with autograft from iliac crest.14 The study consisted of 304 patients with single-level L4-5 or L5-S1 degenerative disc disease and chronic low back pain. Clinical success was defined as at least 15 points (25%) improvement in Oswestry Disability Index (ODI) scores versus baseline data, no evidence of implant failure, absence of major complications, and maintenance or improvement of neurologic status. There were no differences in operative time, blood loss, or level of surgery between the two treatment groups. Length of hospitalization was significantly shorter in patients with TDR (3.7 vs. 4.2 days, P = .0039). TDR patients also enjoyed statistically greater improvement in visual analogue scale (VAS) and ODI scores at 12 months. However, this difference disappeared at 24 months. The VAS score was 40.6 in the TDR group and 34.1 in the fusion group. The ODI score change at 24 months was 48.5% for the TDR group and 42.4% for the fusion group. Zigler et al. reported the results of a similarly designed randomized clinical trial evaluating Prodisc-L TDR versus ALIF combined with dorsolateral fusion and instrumentation.15 The TDR group experienced statistically significant less intraoperative blood loss, operative time, and length of stay. These results are not surprising, considering that the control group underwent additional dorsal surgery. In contrast to Blumenthal et al.’s study,14 clinical success in Zigler et al.’s study was defined as at least 15% improvement in ODI score. At 24 months, ODI scores were similar in the two treatment groups. The VAS improvements for TDR patients and fusion patients were 39 and 32, respectively. Guyer et al reported on 5-year outcomes of Charité TDR RCT.16 The results showed a 57.8% success rate in the TDR group versus 51.2% in the fusion patients (P = .0359). No statistically significant differences were detected in ODI, VAS pain scores, or 36-Item Short Form Health Survey functional outcomes. However, 65.6% of TDR patients were employed at 5 years after surgery compared to 46.5% of fusion patients (P = .0403). Zindrick et al. performed an extensive review of the TDR literature from 1990 to 2007.17 The majority of studies were excluded, owing to lack of relevant data. The remaining clinical reports (level 3 or 4 evidence) often lacked consistency in outcomes or did not use a control group, precluding any meaningful conclusion. On the basis of available level I and II evidence, TDR does not result in better improvement of symptoms and function even against suboptimal controls.

Total Disc Replacement Maintains or Restores Motion at Affected Segments

McAfee et al. analyzed flexion-extension and translation angles in patients from the Charité IDE study.10 At 24 months, the TDR group demonstrated a 13.6% increase in range of motion compared to baseline. Interestingly, 40% of Charité TDR patients showed 5 degrees of motion less than baseline. These patients were potentially fused at 2 years using Food and Drug Administration criteria (adequate motion = 5 degrees or more; fusion = 5 degrees or less). Zigler et al. reported flexion-extension range of motion of 7.7 ± 4.67 degrees in a Prodisc-L IDE trial.15 Guyer el al. reported no change in range of motion at 5-year follow up.16 Despite these limitations, these results suggest early maintenance of range of motion with TDR.

Total Disc Replacement Maintains or Restores Motion to the Adjacent Segment—Does This Translate to a Decreased Incidence of Adjacent-Level Disease?

Adjacent-level disease is a well-recognized potential consequence of lumbar fusion. Harrop et al. performed a meta-analysis of available literature focusing on adjacent-level disease after fusion and TDR.18 The authors concluded that adjacent-level disease developed in 34% of patients after lumbar fusion and 9% after TDR. Fourteen percent of fusion patients developed clinically significant symptoms related to adjacent-level disease compared to 1% of TDR patients. Using odds ratio analysis, the authors concluded that fusion patients are 4.67 times more likely to develop adjacent-segment disease than TDR patients are. Huang et al. evaluated the relationship between range of motion and adjacent-level disease in patients with TDR. Lateral lumbar radiographs of 42 patients were analyzed.19 The authors defined adjacent-level disease as a loss of motion, disc height narrowing, and osteophyte formation. Ten patients (24%) developed radiographic evidence of adjacent-level disease. These findings correlated with loss of motion at the index TDR level. Putzier et al. reported similar findings in their series.20 These data suggest that the development of adjacent-level disease is greater in patients with lumbar fusion. No level 1 or 2 data are available to address the issue of adjacent-level disease.

References

1. Thalgott J.S., Albert T.J., Vacaro A.R., et al. A new classification system for degenerative disc disease of the lumbar spine based on MRI, provocative discography, plain radiographs, and anatomic considerations. Spine J. 2004;4(Suppl 6):S167-S172.

2. Aprill C., Bogduk N. High intensity zone: a diagnostic sign of painful lumbar disc on MRI. Br J Radiol. 1992;65(773):361-369.

3. Kuslich S.D., Ulstrom C.L. The tissue origin of low back pain and sciatic: a report of pain response to tissue stimulation during operation on lumbar spine using local anesthesia. Orthop Clin North Am. 1991;22(2):181-187.

4. Weinstein J.W., Claverie W., Gibson S. The pain of discography. Spine (Phila Pa 1976). 1988;13:1344-1348.

5. Buttner-Janz K., Hahn S., Schikora K., et al. Principles for successful application of the Link SB Charité artificial disc. Orthopade. 2002;31:441-453.

6. German J.W., Foley K.T. Disc arthroplasty in the management of the painful lumbar motion segment. Spine (Phila Pa 1976). 2005;30:S60-S67.

7. Huang R.C., Girardi F.P., Cammisa F.P., et al. Correlation between range of motion and outcome after lumbar total disc replacement: 8.6-year follow-up. Spine (Phila Pa 1976). 2005;30:1407-1411.

8. Kurtz S.M., Peloza J., Sisky R., et al. Analysis of a retrieved polyethylene total disc replacement component. Spine (Phila Pa 1976) J. 2005;5:344-350.

9. Lui J., Ebraheim N.A., Haman S.P., et al. Effect of the increase in the height of lumbar disc space on facet joint articulation area in sagittal plane. Spine (Phila Pa 1976). 2006;31:E198-E202.

10. McAfee P.C., Cunningham B., Holsapple G., et al. A prospective, randomized, multi-center food and drug administration investigational device exemption study of total lumbar disc replacement with the Charité artificial disc versus lumbar fusion. Part II: evaluation of radiographic outcomes and correlation of surgical technique accuracy with clinical outcomes. Spine (Phila Pa 1976). 2005;30:1576-1583.

11. Steiber J.R., Donald G.D. Early failure of lumbar disc replacement: case report and review of the literature. J Spinal Disord Tech. 2006;19(1):55-60.

12. Van Ooij A., Oner F.C., Verbout A.J. Complications of artificial disc replacement; a report of 27 patients with the SB Charité disc. J Spinal Disord Tech. 2003;16:369-383.

13. Huang R.C., Lim M.R., Girardi F.P., et al. The prevalence of contraindications to total disc replacement in a cohort of lumbar surgical patients. Spine (Phila Pa 1976). 2004;29:2538-2541.

14. Blumenthal S., McAfee P.C., Guyer R.D., et al. A prospective, randomised multi-centre Food & Drug Administration investigational device exemption study of lumbar total disc replacement with the Charité artificial disc versus lumbar fusion. Part I: evaluation of clinical outcomes. Spine (Phila Pa 1976). 2005;30:1565-1575.

15. Zigler J., Delamarter R., Spivak J.M., et al. Results of prospective randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential fusion for the treatment of 1-level degenerative disc disease. Spine (Phila Pa 1976). 2007;32:1155-1163.

16. Guyer R.D., McAfee P.C., Banco R.J., et al. Prospective, randomized multicenter Food and Drug Administration investigational device exemption study of lumbar total disc replacement with the CHARITE artificial disc versus lumbar fusion: five-year follow up. Spine (Phila Pa 1976). 2009;9:374-386.

17. Zindrick M.R., Tzermiadianos M.N., Voronov L.I., et al. An evidence-based medicine approach in determining factors that may affect outcome in lumbar total disc replacement. Spine (Phila Pa 1976). 2008;33:1262-1269.

18. Harrop J.S., Youseff J.A., Maltenfort M., et al. Lumbar adjacent segmental degeneration and disease after arthrodesis and total disc arthroplasty. Spine (Phila Pa 1976). 2008;33:1701-1707.

19. Huang R.C., Tropiano P., Marnay T., et al. Range of motion and adjacent level degeneration after lumbar total disc replacement. Spine J. 2006;6:242-247.

20. Putzier M., Funk J.F., Schneider S.V., et al. Charité total disc replacement—clinical and radiographic results after an average follow up of 17 years. Eur Spine J. 2006;15:183-195.

Total Disc Arthroplasty

Lumbar Artificial Disc

Mechanical low back pain continues to be a major cause of morbidity. The diagnosis and management of mechanical low back pain are responsible for a significant portion of annual health-care costs. The etiology of mechanical low back pain (LBP) is multifactorial but may, in part, be related to segmental degenerative changes. Mechanical LBP may be difficult to accurately diagnose and effectively treat. Patients with mechanical LBP are first managed conservatively with therapies that include epidural steroid injections, nonsteroidal anti-inflammatory agents, oral narcotic medications, and physical therapy to strengthen core muscles. If conservative measures are exhausted without relief, surgical intervention may be considered. The surgical management of mechanical LBP has historically centered on fusion of the abnormal or dysfunctional motion segment, with subsequent loss of motion.

It has been opined that the fusion of a spine motion segment leads to increased adjacent-segment degenerative changes. The incidence of such changes has been reported to range from 10% to 30%,110 which has led to the development and evolution of other treatment modalities for mechanical LBP, including artificial disc replacement. Lumbar artificial disc replacement facilitates the relief of pain by eliminating presumed pain generators (including the annulus fibrosus and nucleus pulposus) while preserving motion, thereby allegedly minimizing the development of adjacent-segment disease.

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