Spine surgery has seen parallel interest and development in the areas of motion preservation and minimally invasive surgery. Posterior microendoscopic laminoforaminotomy (MELF) allows for neural decompression while maintaining motion via a minimally invasive approach. This technique shares the advantage of maintenance of motion with arthroplasty, but without the need for instrumentation. Therefore, the procedure is motion preserving, minimally invasive and cost-effective. The ideal indications for posterior MELF include unilateral radiculopathy secondary to “hard disc” or spondylosis, as well as soft disc herniations. The authors present a modified surgical technique for posterior MELF as well as a case study illustrating its synergy with anterior arthroplasty.
Domagoj Coric and Tim Adamson
Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2007
Domagoj Coric and Praveen V. Mummaneni
✓ Nucleus replacement offers a less invasive alternative to traditional fusion or total disc replacement techniques in the treatment of symptomatic lumbar degenerative disc disease (DDD). The authors discuss the classification of nucleus replacement devices as well as their potential indications. The authors review the history and evolution of nucleus replacement devices emphasizing several that are actively in US Investigational Device Exemption pilot feasibility trials. Nucleus replacement devices can be functionally categorized as elastomeric and mechanical. A classification scheme is discussed. Nucleus replacement remains investigational, but early clinical results have been encouraging. Further clinical investigation with well-designed prospective, randomized pivotal trials is needed to determine the efficacy of nucleus replacement in the treatment of lumbar DDD, as well as its ideal indications.
Kris Radcliff, Domagoj Coric and Todd Albert
The purpose of this study was to report the outcome of a study of 2-level cervical total disc replacement (Mobi-C) versus anterior cervical discectomy and fusion (ACDF). Although the long-term outcome of single-level disc replacement has been extensively described, there have not been previous reports of the 5-year outcome of 2-level cervical disc replacement.
This study reports the 5-year results of a prospective, randomized US FDA investigational device exemption (IDE) study conducted at 24 centers in patients with 2-level, contiguous, cervical spondylosis. Clinical outcomes at up to 60 months were evaluated, including validated outcome measures, incidence of reoperation, and adverse events. The complete study data and methodology were critically reviewed by 3 independent surgeon authors without affiliation with the IDE study or financial or institutional bias toward the study sponsor.
A total of 225 patients received the Mobi-C cervical total disc replacement device and 105 patients received ACDF. The Mobi-C and ACDF follow-up rates were 90.7% and 86.7%, respectively (p = 0.39), at 60 months. There was significant improvement in all outcome scores relative to baseline at all time points. The Mobi-C patients had significantly more improvement than ACDF patients in terms of Neck Disability Index score, SF-12 Physical Component Summary, and overall satisfaction with treatment at 60 months. The reoperation rate was significantly lower with Mobi-C (4%) versus ACDF (16%). There were no significant differences in the adverse event rate between groups.
Both cervical total disc replacement and ACDF significantly improved general and disease-specific measures compared with baseline. However, there was significantly greater improvement in general and disease-specific outcome measures and a lower rate of reoperation in the 2-level disc replacement patients versus ACDF control patients.
Clinical trial registration no. NCT00389597 (clinicaltrials.gov)
Prospective randomized controlled study of the Bryan Cervical Disc: early clinical results from a single investigational site
Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2005
Domagoj Coric, Frederick Finger and Peggy Boltes
The authors report on a prospective randomized controlled multicenter trial in which they compared the clinical outcomes obtained in patients who underwent the placement of a Bryan Cervical Disc System with those obtained in patients who underwent anterior cervical discectomy and fusion (ACDF). In the present study, they evaluated the safety and effectiveness of the artificial disc based on data obtained at a single investigational site.
Patients with primary, single-level cervical disc disease producing radiculopathy and/or myelopathy were randomized prospectively to undergo anterior cervical discectomy with either fusion or artificial disc placement. The patients were evaluated with pre- and postoperative serial radiographic studies; the authors also evaluated neck disability indices, visual analog scale scores for pain, 36-Item Short Form Health Survey scores, and neurological status at 1.5, 3, 6, 12, and 24 months.
Analysis of the early results obtained in the 33 patients indicated an absence of device-related complications. Preliminary analysis revealed that improvement in all clinical outcome measures was excellent for both treatment groups; however, in patients treated with the artificial cervical disc, motion at the treated level was maintained.
The preliminary results documented at this investigational site are encouraging. Evaluation of data acquired in the Bryan disc treatment group showed that improvements in the clinical parameters were similar to those in the fusion group. Additionally in the artificial disc–treated group, there was radiographic evidence that motion was maintained.
It is theorized that motion preservation may potentially reduce the rate of adjacent-level cervical disc disease that has been documented in patients who undergo ACDF.
Domagoj Coric and Charles L. Branch Jr.
Lumbar spinal stenosis is often the result of advanced degeneration of motion segments of the lumbar spine. Loss of disc height, facet displacement and hypertrophy, spondylosis, and spondylolisthesis, as well as buckling of the ligamentum flavum and annulus fibrosus, all contribute to impingement on the spinal canal and intervertebral foramen in lumbar stenosis. There is a subgroup of patients with spinal stenosis in whom the spine is unstable preoperatively or becomes destabilized following decompression who would benefit from an initial fusion procedure. Posterior lumbar interbody fusion (PLIF) addresses several aspects of the multifactorial pathophysiology responsible for spinal stenosis and may arrest the degenerative changes at the fused level. Fusion, in particular PLIF, should be considered in complex cases of lumbar spinal stenosis, most notably in patients with postlaminectomy stenosis or stenosis associated with spondylolisthesis.
Domagoj Coric, John Parish and Margaret O. Boltes
There has been a steady evolution of cervical total disc replacement (TDR) devices over the last decade resulting in surgical technique that closely mimics anterior cervical discectomy and fusion as well as disc design that emphasizes quality of motion. The M6-C TDR device is a modern-generation artificial disc composed of titanium endplates with tri-keel fixation as well as a polyethylene weave with a polyurethane core. Although not yet approved by the FDA, M6-C has finished a pilot and pivotal US Investigational Device Exemption (IDE) study. The authors present the surgical technique for implantation of a 2-level M6-C cervical TDR device.
The video can be found here: https://youtu.be/rFEAqINLRCo.
Domagoj Coric, Joseph Cassis, John D. Carew and Margaret O. Boltes
Cervical total disc replacement (TDR) was developed to address some of the shortcomings associated with anterior cervical discectomy and fusion (ACDF) by preserving motion at the treated level. To establish an evidence-based rationale for cervical TDR to serve as a viable alternative to ACDF, cervical arthroplasty must establish equivalent or superior clinical outcomes while maintaining motion. The authors report on 98 patients from a single investigational site involved in 3 separate prospective, randomized, controlled investigational device exemption multicenter trials comparing cervical arthroplasty to ACDF with a 2–6-year follow-up.
Patients with 1- and 2-level cervical disc disease producing radiculopathy and/or myelopathy were randomized prospectively under 3 separate investigational device exemption pivotal trials to undergo ACDF with plate or artificial disc placement. The 3 arthroplasty systems evaluated were the Bryan cervical disc, Kineflex/C disc, and Discover cervical disc. The patients were evaluated with pre- and postoperative serial neurological examinations, radiographs, and clinical outcome indices at 1, 3, 6, 12, 24, 36, 48, and 60 months.
Ninety-eight patients were treated at the authors' single investigational site. Fifty-seven of these patients underwent cervical arthroplasty and 41 underwent ACDF. A minimum 24-month follow-up was available for 90 patients (92%; 53 in the combined arthroplasty group and 37 in the combined ACDF group) with a follow-up duration ranging from 24 to 67 months (mean 38 months). Clinical success, defined as a composite measure consisting of 5 separate components, was significantly higher in the combined arthroplasty group (85%) compared with the combined ACDF group (70%; p = 0.035). The Neck Disability Index and visual analog scale patient self-report measures were evaluated at 3–24-months follow-up, and all groups showed excellent clinical outcomes. All groups (Bryan, Kineflex/C, Discover, and ACDF) showed statistically significant improvement from the preoperative period to a minimum 2-year follow-up (p < 0.0001). Overall, angular motion was improved by 0.91° in the combined arthroplasty group and reduced by 7.8° in the combined ACDF group (p < 0.0001). In the ACDF group there was a fusion rate of 97% (36 of 37 cases). In the arthroplasty group there was a 5.6% incidence of bridging heterotopic ossification (3 cases). There were a total of 4 reoperations (7.5%) in the combined arthroplasty group with 1 (1.9%) at the adjacent level. There were 3 reoperations (8.1%) in the ACDF group, all at the adjacent level.
The prospective, intermediate-term (average follow-up > 3 years) results of cervical TDR at the authors' site are encouraging. Patients treated with the artificial discs showed significantly better clinical results, maintained motion at the treated level, and trended toward less adjacent-level disease.
Domagoj Coric, Praveen V. Mummaneni, Vincent Traynelis and Jeffrey Wang
Domagoj Coric, John A. Wilson and David L. Kelly Jr
✓ Current treatment regimens for hangman's fracture, or traumatic spondylolisthesis of the axis, emphasize rigid immobilization using a halo orthosis. A retrospective study was undertaken to assess the safety and efficacy of nonrigid immobilization in the treatment of these fractures.
Records of 64 patients with hangman's fracture treated over a 19-year period (1975–1994) at one institution were reviewed. Thirty-nine of these patients presented with a displacement of C-2 onto C-3 measuring less than 6 mm and no contiguous cervical fractures. All these patients were treated with nonrigid immobilization, consisting primarily of a Philadelphia hard collar worn for 10 to 14 weeks; all showed stable fracture healing on follow-up flexion—extension radiographs. None of the patients experienced neurological sequelae or significant disability at follow-up review.
The results of this series indicate that the majority of patients with hangman's fractures, including all patients with displacement measuring less than 6 mm and no contiguous fractures, may be treated successfully with nonrigid immobilization. This management regimen avoids the increased morbidity and cost associated with rigid immobilization using a halo orthosis.
Jeffrey D. Jenkins, Domagoj Coric and Charles L. Branch Jr.
Object. The optimal treatment of Type II odontoid fractures is controversial. Various therapies have been used, including nonrigid immobilization, halo orthosis, posterior atlantoaxial arthrodesis, and odontoid screw fixation. Of these, odontoid screw fixation is the only treatment modality that provides immediate stabilization and preserves normal motion at C1–2. It has been suggested in cadaveric biomechanical studies that there is no advantage to using more than one screw for anterior odontoid fixation. The authors compared the clinical safety and efficacy of one- and two-screw anterior odontoid fixation.
Methods. The authors retrospectively reviewed the medical records and radiographs of 42 consecutive patients who had undergone fixation for treatment of odontoid fractures at a single institution between 1989 and 1995.
The group treated with a single screw consisted of 20 patients (11 males and nine females) with an average age of 54 years. The union rate in this group, as determined by postoperative dynamic radiographs, was 81%. The group treated with two screws consisted of 22 patients (13 men and nine women) with an average age of 64 years, whose union rate was 85%.
Conclusions. Anterior odontoid screw fixation is a safe and efficacious treatment for odontoid fractures. In the authors' experience there was no significant difference in the successful union rates achieved with either the one- or two-screw fixation techniques (81% and 85%, respectively; χ2 = 0.09, p = 0.76).