Prospective, multicenter clinical trial comparing the M6-C compressible cervical disc with anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical radiculopathy: 5-year results of an FDA investigational device exemption study

BACKGROUND CONTEXT

Various total disc replacement (TDR) designs have been compared to anterior cervical discectomy and fusion (ACDF) with favorable short and long-term outcomes in FDA-approved investigational device exemption (IDE) trials. The unique design of M6-C, with a compressible viscoelastic nuclear core and an annular structure, has previously demonstrated favorable clinical outcomes through 24 months.

PURPOSE

To evaluate the long-term safety and effectiveness of the M6-C compressible artificial cervical disc and compare to ACDF at 5 years.

STUDY DESIGN

Prospective, multicenter, concurrently and historically controlled, FDA-approved IDE clinical trial.

PATIENT SAMPLE

Subjects with one-level symptomatic degenerative cervical radiculopathy were enrolled and received M6-C (n=160) or ACDF (n=189) treatment as part of the IDE study. Safety outcomes were evaluated at 5 years for all subjects. The primary effectiveness endpoint was available at 5 years for 113 M6-C subjects and 106 ACDF controls.

OUTCOME MEASURES

The primary endpoint of this analysis was composite clinical success (CCS) at 60 months. Secondary endpoints were function and pain (neck disability index, VAS), physical quality of life (SF-36, SF-12), safety, neurologic, and radiographic assessments.

METHODS

Propensity score subclassification was used to control for selection bias and match baseline covariates of the control group to the M6-C subjects. Sixty-month CCS rates were estimated for each treatment group using a generalized linear model controlling for propensity score.

RESULTS

At 5 years postoperatively, the M6-C treatment resulted in 82.3% CCS while the ACDF group showed 67.0% CCS (superiority p=.013). Secondary endpoints indicated that significantly more M6-C subjects achieved VAS neck and arm pain improvements and showed maintained or improved physical functioning on quality-of-life measures compared to baseline assessments. The M6-C group-maintained flexion-extension motion, with significantly greater increases from baseline disc height and disc angle than observed in the control group. The rates of M6-C subsequent surgical interventions (SSI; 3.1%) and definitely device- or procedure-related serious adverse events (SAE failure; 3.1%) were similar to ACDF rates (SSI=5.3%, SAE failure=4.8%; p>.05 for both).

CONCLUSIONS

Subjects treated with the M6-C artificial disc demonstrated superior 5-year achievement of clinical success when compared to ACDF controls. In addition, significantly more subjects in the M6-C group showed improved pain and physical functioning scores than observed in ACDF subjects, with no difference in reoperation rates or safety outcomes.

Prospective, multicenter clinical trial comparing M6-C compressible six degrees of freedom cervical disc with anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical radiculopathy: 2-year results of an FDA investigational device exemption study

BACKGROUND CONTEXT

Various designs of total disc replacement (TDR) devices have been compared to anterior cervical discectomy and fusion (ACDF) with favorable outcomes in FDA-approved investigational device exemption trials. The design of M6-C with a compressible viscoelastic nuclear core and an annular structure is substantially different than prior designs and has previously demonstrated favorable kinematics and clinical outcomes in small case series.

PURPOSE

To evaluate the safety and effectiveness of the novel M6-C compressible artificial cervical disc compared with ACDF for subjects with single-level degenerative cervical radiculopathy.

STUDY DESIGN/SETTING

Prospective, multicenter, concurrently and historically controlled, FDA-approved investigational device exemption clinical trial.

PATIENT SAMPLE

Subjects with one-level symptomatic degenerative cervical radiculopathy were enrolled and assigned to receive M6-C or ACDF.

OUTCOME MEASURES

Pain and function (Neck Disability Index, VAS), quality of life (SF-36), safety, neurologic, and radiographic assessments of motion (both flexion extension and lateral bending) were performed. The primary clinical endpoint was composite clinical success (CCS) at 24 months.

METHODS

Using propensity score subclassification to control for selection bias, 160 M6-C subjects were compared to a matched subset of 189 ACDF controls (46 concurrent and 143 historical controls).

RESULTS

Both ACDF and M6-C subjects reported significant improvements in patient-reported outcomes at all time points over baseline. Overall SF-36 Physical Component Score and neck and arm pain scores were significantly improved for M6-C as compared to ACDF treatment. CCS and mean Neck Disability Index improvements were similar between M6-C and ACDF. Correspondingly, there were significantly fewer subjects that utilized pain medication or opioids following M6-C treatment at 24 months relative to baseline. Range of motion was maintained in subjects treated with M6-C. Subsequent surgical interventions, dysphagia rates, and serious adverse events were comparable between groups.

CONCLUSIONS

M6-C treatment demonstrated both safety and effectiveness for the treatment of degenerative cervical radiculopathy. Treatment with M6-C demonstrated noninferiority for the primary endpoint, indicating a similar ability to achieve CCS at 24 months. However, for the secondary endpoints, M6-C subjects demonstrated significantly improved pain and function compared to ACDF subjects, while maintaining range of motion, improving quality of life, and decreasing analgesic and opioid usage at 2 years postoperatively relative to baseline.

Thrombophilic abnormalities in patients with or without pulmonary embolism following elective spinal surgery: a pilot study

BACKGROUND

Significance of the thrombophilic abnormalities in development of venous thromboembolism (VTE) has been studies with total hip arthroplasty and acute traumatic spinal cord injury. However, their role as risk factors for VTE in elective spinal surgery remains to be determined.

QUESTIONS/PURPOSES

To determine the role of thrombophilic abnormalities in the development of pulmonary embolism (PE) following elective spine surgery.

METHODS

Case and control groups were created in patients who had undergone elective spinal surgery for degenerative conditions. The PE group comprised 12 patients whose post-operative course was complicated by development of PE. The control group included 12 patients with an uneventful post-operative course. Demographic data including age, gender and surgical procedures were matched between the PE group and the control group. Both groups were evaluated for thrombophilic and hypofibrinolytic risk factors at 3 months post-operatively or later. Blood tests were performed to measure fasting serum homocysteine, antithrombin III, and protein C. Molecular genetic testing was conducted for detection of the plasminogen activator inhibitor-1 4G/4G, and prothrombin 3 UTR gene mutations.

RESULTS

Heterozygous mutation (G20201A) of prothrombin was detected in two patients (16.7%) in the PE group, whereas no such mutation was noted in the control group. Plasminogen activator inhibitor-1 4G/4G homozygous mutation was seen in three in the PE group and two in the control group. Of homocysteine, antithrombin III and protein C, only one patient in each group showed abnormal levels of homocysteine. In total, there half of the patients in the PE group had at least one thrombophilic abnormality, whereas three (25%) patients showed such abnormality in the control group.

CONCLUSION

These findings suggest the involvement of thrombophilic abnormalities, especially the heterozygous G20201A mutation, in the development of PE in patients undergoing elective spinal surgery.

Surgical versus nonsurgical therapy for lumbar spinal stenosis

BACKGROUND

Surgery for spinal stenosis is widely performed, but its effectiveness as compared with nonsurgical treatment has not been shown in controlled trials.

METHODS

Surgical candidates with a history of at least 12 weeks of symptoms and spinal stenosis without spondylolisthesis (as confirmed on imaging) were enrolled in either a randomized cohort or an observational cohort at 13 U.S. spine clinics. Treatment was decompressive surgery or usual nonsurgical care. The primary outcomes were measures of bodily pain and physical function on the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and the modified Oswestry Disability Index at 6 weeks, 3 months, 6 months, and 1 and 2 years.

RESULTS

A total of 289 patients were enrolled in the randomized cohort, and 365 patients were enrolled in the observational cohort. At 2 years, 67% of patients who were randomly assigned to surgery had undergone surgery, whereas 43% of those who were randomly assigned to receive nonsurgical care had also undergone surgery. Despite the high level of nonadherence, the intention-to-treat analysis of the randomized cohort showed a significant treatment effect favoring surgery on the SF-36 scale for bodily pain, with a mean difference in change from baseline of 7.8 (95% confidence interval, 1.5 to 14.1); however, there was no significant difference in scores on physical function or on the Oswestry Disability Index. The as-treated analysis, which combined both cohorts and was adjusted for potential confounders, showed a significant advantage for surgery by 3 months for all primary outcomes; these changes remained significant at 2 years.

CONCLUSIONS

In the combined as-treated analysis, patients who underwent surgery showed significantly more improvement in all primary outcomes than did patients who were treated nonsurgically. (ClinicalTrials.gov number, NCT00000411 [ClinicalTrials.gov].).

Screening for nuclear replacement candidates in patients with lumbar degenerative disc disease

BACKGROUND

Nuclear replacement is an emerging surgical treatment for degenerative disc disease (DDD) and low back pain (LBP). While clinical experience is most extensive with the prosthetic disc nucleus PDN (Raymedica, Minneapolis, Minnesota), strict indications apply for the implantation of this device. The purpose of this study was to ascertain what percentage of patients treated surgically for degenerative disc disease with other surgical procedures would have been candidates for nuclear replacement implantation.

METHODS

The charts and films of 85 consecutive patients with failed conservative management for LBP treated surgically with fusion, disc replacement, or annuloplasty were retrospectively reviewed. There were 53 patients with 1-level disease and 32 with 2-level disease, accounting for 117 treated levels. Patients with the following radiographic contraindications to nuclear replacement were serially eliminated: (1) Schmorl's nodes and > 50% collapse of the disc space, (2) irregular/convex endplates on the MRI, (3) complete tears and large annular defects (ie, both incomplete tears and complete tears were eliminated, but patients with local annular deficiency were deemed eligible for nuclear replacement), and (4) a BMI > 30.

RESULTS

Fifty-nine levels (50.4%) had no radiographic contraindications to treatment with a nuclear replacement device. Twelve levels in 10 patients with a BMI > 30 were excluded. Overall, 47 out of 117 levels (40.2%) had no contraindications to a prosthetic nucleus device. The L5-S1 level was the most commonly treated level (55 out of 117, 47%), but only 25.5% had no radiographic contraindications, and overall only 21.8% of the levels were suitable for a nuclear replacement device. Upper lumbar levels (L3-4 and L4-5) had no radiographic contraindications in a higher percentage of cases (68.8% and 72.7%, respectively). The inclusion of the BMI criteria reduced these percentages to 50% and 59.1%, respectively.

CONCLUSIONS

The surgeon has to assess endplate integrity, disc height, endplate shape, annular integrity, and BMI when offering nuclear replacement as treatment for patients with DDD.

Results of the 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

STUDY DESIGN

A prospective, randomized, multicenter, Food and Drug Administration-regulated Investigational Device Exemption clinical trial.

OBJECTIVE

To evaluate the safety and effectiveness of the ProDisc-L (Synthes Spine, West Chester, PA) lumbar total disc replacement compared to circumferential spinal fusion for the treatment of discogenic pain at 1 vertebral level between L3 and S1.

SUMMARY OF BACKGROUND DATA

As part of the Investigational Device Exemption clinical trial, favorable single center results of lumbar total disc replacement with the ProDisc-L have been reported previously.

METHODS

Two hundred eighty-six (286) patients were treated on protocol. Patients were evaluated before and after surgery, at 6 weeks, 3, 6, 12, 18, and 24 months. Evaluation at each visit included patient self-assessments, physical and neurologic examinations, and radiographic evaluation.

RESULTS

Safety of ProDisc-L implantation was demonstrated with 0% major complications. At 24 months, 91.8% of investigational and 84.5% of control patients reported improvement in the Oswestry Low Back Pain Disability Questionnaire (Oswestry Disability Index [ODI]) from preoperative levels, and 77.2% of investigational and 64.8% of control patients met the > or =15% Oswestry Disability Index improvement criteria. Overall neurologic success in the investigational group was superior to the control group (91.2% investigational and 81.4% control; P = 0.0341). At 6 weeks and 3 months follow-up time points, the ProDisc-L patients recorded SF-36 Health Survey scores significantly higher than the control group (P = 0.018, P = 0.0036, respectively). The visual analog scale pain assessment showed statistically significant improvement from preoperative levels regardless of treatment (P < 0.0001). Visual analog scale patient satisfaction at 24 months showed a statistically significant difference favoring investigational patients over the control group (P = 0.015). Radiographic range of motion was maintained within a normal functional range in 93.7% of investigational patients and averaged 7.7 degrees.

CONCLUSIONS

ProDisc-L has been found to be safe and efficacious. In properly chosen patients, ProDisc-L has been shown to be superior to circumferential fusion by multiple clinical criteria.

Failed degenerative lumbar spine surgery

Significant back and leg symptoms develop in approximately 10%-15% of patients who have undergone a spinal decompression procedure and approximately 15%-20% of patients who have had a spinal fusion procedure for degenerative disease of the lumbar spine during the ensuing 3-5 year so that they require revision lumbar surgery. The cause for their symptoms has to be diligently looked for, as that is a main predictor of good outcome following revision surgery. Good history taking, including a detailed old chart review, repeat physical evaluation, and input from therapists--physical and psychological, neurologist, and other caregivers--should be sought. These, together with intelligent use of investigations, go a long way in helping establish a cause for failure. Furthermore, developing a revision surgical strategy is also an intellectual exercise in which a simple algorithmic approach may not always work. The process of evaluation and surgical management for failed lumbar degeneration is a science and an art that requires a great deal of understanding and commitment on the part of the surgeon. The temporal trend of improving outcomes is aided in part by emerging technologies, however, one has to be constantly aware of simple factors that influence outcome. The use of published literature and experiences of peers helps one offer appropriate surgical intervention while improving the long-term results of revision surgery of the lumbar spine.

Transforaminal epidural steroid injections in lumbosacral radiculopathy: a prospective randomized study

STUDY DESIGN

A prospective study randomized by patient choice from the private practice of a single physician affiliated with a major teaching hospital was conducted.

OBJECTIVES

To compare transforaminal epidural steroid injections with saline trigger-point injections used in the treatment of lumbosacral radiculopathy secondary to a herniated nucleus pulposus.

SUMMARY OF BACKGROUND DATA

Epidural steroid injections have been used for more than half a century in the management of lumbosacral radicular pain. At this writing, however, there have been no controlled prospective trials of transforaminal epidural steroid injections in the treatment of lumbar radiculopathy secondary to a herniated nucleus pulposus.

METHODS

Randomized by patient choice, patients received either a transforaminal epidural steroid injection or a saline trigger-point injection. Treatment outcome was measured using a patient satisfaction scale with choice options of 0 (poor), 1 (fair), 2 (good), 3 (very good), and 4 (excellent); a Roland-Morris low back pain questionnaire that showed improvement by an increase in score; a measurement of finger-to-floor distance with the patient in fully tolerated hip flexion; and a visual numeric pain scale ranging from 0 to 10. A successful outcome required a patient satisfaction score of 2 (good) or 3 (very good), improvement on the Roland-Morris score of 5 or more, and pain reduction greater than 50% at least 1 year after treatment. The final analysis included 48 patients with an average follow-up period of 16 months (range, 12-21 months).

RESULTS

After an average follow-up period of 1.4 years, the group receiving transforaminal epidural steroid injections had a success rate of 84%, as compared with 48% for the group receiving trigger-point injections (P < 0.005).

CONCLUSION

Fluoroscopically guided transforaminal injections serve as an important tool in the nonsurgical management of lumbosacral radiculopathy secondary to a herniated nucleus pulposus.

Nonoperative treatment for lumbar spinal stenosis. Clinical and outcome results and a 3-year survivorship analysis

STUDY DESIGN

A cohort study of nonoperatively treated patients with lumbar spinal stenosis.

OBJECTIVE

To assess the effectiveness of aggressive nonsurgical treatment for lumbar spinal stenosis.

BACKGROUND DATA

While surgical treatment of lumbar spinal stenosis has been widely accepted, the natural history of this condition is poorly documented. Moreover, the effect of other available therapies is unclear.

METHODS

Forty-nine patients meeting radiographic and clinical criteria for spinal stenosis underwent nonsurgical intervention consisting of therapeutic exercises, analgesics, and epidural steroid injections. Patients were followed for an average of 33 months. Outcome was assessed using a recently developed patient questionnaire for assessment of patients with lumbar spinal stenosis. Survival analysis was used to assess the probability of surgical intervention over the follow-up period.

RESULTS

At 3 years following treatment, 9 of the 49 patients had undergone surgical intervention. Of the remaining 40 unoperated patients, it is reported that two suffered significant motor deterioration, one of whom still reported overall symptoms as mild improvement, and the other as definite worsening. Five of the 40 unoperated patients reported feeling overall symptoms as probably or definitely worse, 12 reported no change, 11 reported only mild improvement, and 12 reported sustained improvement. Twelve of the 40 unoperated patients also had none or only mild pain.

CONCLUSIONS

The authors conclude that aggressive nonoperative treatment for spinal stenosis remains a reasonable option.