Bengt Lind

Intermediate follow-up after treatment of degenerative disc disease with the Bryan Cervical Disc Prosthesis: Single-level and bi-level

Study Design. Prospective, concurrently enrolled, multicenter trials of the Bryan Cervical Disc Prosthesis (Medtronic Sofamor Danek, Memphis, TN) were conducted for the treatment of patients with single-level and two-level (bi-level) degenerative disc disease of the cervical spine. Objectives. The studies were designed to determine whether new functional intervertebral cervical disc prosthesis can provide relief from objective neurologic symptoms and signs, improve the patient’s ability to perform activities of daily living, decrease pain, and maintain stability and segmental motion. Summary of Background Data. The concept of accelerated degeneration of adjacent disc levels as a consequence of increased stress caused by interbody fusion of the cervical spine has been widely postulated. Therefore, reconstruction of a failed intervertebral disc with functional disc prosthesis should offer the same benefits as fusion while simultaneously providing motion and thereby protecting the adjacent level discs from the abnormal stresses associated with fusion. Methods. Patients with symptomatic cervical radiculopathy and/or myelopathy underwent implantation with the Bryan prosthesis after a standard anterior cervical discectomy. At scheduled follow-up periods, the effectiveness of the device was characterized by evaluating each patient’s pain, neurologic function, and radiographically measured range of motion at the implanted level. Results. Clinical success for both studies exceeded the study acceptance criteria of 85%. At 1-year follow-up, the flexion-extension range of motion per level averaged 7.9 ± 5.3 degrees in the single-level study and 7.4 ± 5.1 degrees in the bilevel study. No devices have been explanted. Conclusions. Discectomy and implantation of the device alleviates neurologic symptoms and signs similar to anterior cervical discectomy and fusion. Radiographic evidence supports maintenance of motion. The procedure is safe and the patients recover quickly. At least 5 years of follow-up will be needed to assess the long-term functionality of the prosthesis and protective influence on adjacent levels.

Preliminary clinical experience with the Bryan Cervical Disc Prosthesis.

OBJECTIVE The concept of accelerated degeneration of adjacent disc levels as a consequence of increased stress caused by interbody fusion of the cervical spine has been widely postulated. Therefore, reconstruction of a failed intervertebral disc with a functional disc prosthesis should offer the same benefits as fusion while simultaneously providing motion and thereby protecting the adjacent level discs from the abnormal stresses associated with fusion. This study was designed to determine whether a new, functional intervertebral cervical disc prosthesis can provide relief from objective neurological symptoms and signs, improve the patient’s ability to perform activities of daily living, decrease pain, and provide stability and normal range of motion. METHODS We conducted a prospective, concurrently enrolled, multicenter trial of the Bryan Cervical Disc Prosthesis (Spinal Dynamics Corp., Mercer Island, WA) for the treatment of patients with single-level degenerative disc disease of the cervical spine. Patients with symptomatic cervical radiculopathy and/or myelopathy underwent implantation with the Bryan prosthesis after a standard anterior cervical discectomy. At scheduled follow-up periods, the effectiveness of the device was characterized by evaluating each patient’s pain, neurological function, and range of motion at the implanted level. RESULTS Analysis included data regarding 60 patients at 6 months with 30 of those patients at 1 year. Clinical success at 6 months and 1 year after implantation was 86 and 90%, respectively, exceeding the study’s acceptance criteria of 85%. These results compare favorably with the short-term clinical outcomes associated with anterior cervical discectomy and fusion reported in the literature. At 1 year, there was no measurable subsidence of the devices (based on a measurement detection threshold of 2 mm). Evidence of anterior and/or posterior device migration was detected in one patient and suspected in a second patient. There was no evidence of spondylotic bridging at the implanted disc space. The measured range of motion in flexion-extension, as determined by an independent radiologist, ranged from 1 to 21 degrees (mean range of motion, 9 ± 5 degrees). No devices have been explanted or surgically revised. CONCLUSION Discectomy and implantation of the device alleviates neurological symptoms and signs similar to anterior cervical discectomy and fusion. Radiographic evidence supports normal range of motion. The procedure is safe and the patients recover quickly. Restrictive postoperative management is not necessary. However, only after long-term follow-up of at least 5 years will it become clear whether the device remains functional, thus confirming these early favorable results. In addition, the influence on adjacent motion segments can be assessed after at least 5 years of follow-up.

Clinical Significance of Heterotopic Ossification in Cervical Disc Replacement: A Prospective Multicenter Clinical Trial

OBJECTIVE:Heterotopic ossification (HO) is a well-known complication in joint replacements, but its occurrence and clinical effect on cervical artificial discs has not yet been studied. The purpose of this study was to investigate the incidence of HO in cervical disc replacement, to identify any associated risk factors for HO, and to examine the relationship of HO with clinical outcomes. METHODS:The patient data for this observational study were obtained from the original Bryan Disc Study by the European Consortium. Occurrence of HO was defined by the McAfee classification on the cervical lateral x-rays at 12 months after surgery. Secondary outcome measurements included Odoms criteria and the Medical Outcomes Study Short-Form 36-Item Health Survey. RESULTS:Sixteen (17.8%) of the 90 studied patients experienced HO, and 6 (6.7%) of these patients experienced Grade 3 and 4 HO. Ten patients’ (11%) artificial discs were shown to have movement of less than 2 degrees on flexion and extension cervical x-ray at 12 months, with 4 of these patients having HO of Grade 3 or 4. Male sex (&khgr;2 = 4.1; P = 0.0407) and older patients (P = 0.023; odds ratio = 1.10; 95% confidence interval = 1.01–1.19) were associated with development of HO. CONCLUSION:There is a strong association of the occurrence of HO with subsequent loss of movement of the implanted cervical artificial disc. We have found that sex and age are two possible risk factors in the development of HO after cervical disc replacement.

Spinal nerve root compression.

The pathophysiology of sciatica is not completely understood, although our understanding of its causes is increasing. Mechanical alterations combined with inflammatory changes lead to pain. Compression alters nerve root conduction and compromises the nutritional support of spinal nerve roots (through intrinsic and extrinsic vascularity and cerebral spinal fluid percolation). Mechanical forces can lead to intraneural damage and functional changes in nerve roots. Chemical and metabolic effects can create an inflammatory response. Varying causes of inflammation coupled with varying degrees of compression can occur anywhere along the cauda equina or spinal nerve root, including the dorsal root ganglia, and contribute to the pain response and neurologic deficits associated with sciatica.

Halo-vest treatment of unstable traumatic cervical spine injuries.

Eighty-three patients with unstable cervical spine injuries were treated with halo-vest stabilization in a prospective consecutive series during a 10 year period. At the follow-up 2-7 years after the trauma, six patients had died and eight patients had been surgically stabilized. Sixty-seven of the remaining 69 patients (97%) were subjected to the follow-up performed with validated protocols. All patients but three were reexamined clinically and radiographically. Flexion-extension motion and sidebending of the neck was measured radiographically. Rotation was measured with the aid of a compass placed on top of the head of the patient. Fortyfour patients (53%) had initial neurological deficit, 26 with tetraparesls. The age range was 13-89 years and the male/female ratio was 2/1. The halo-vest treatment period was 10-12 weeks. The 1 year healing rate was 90%. Seven nonunions occurred, all in fracture types known to be prone to nonunion. Complications during the treatment were usually minor, with pin problems being the most frequent (pin loosening 60%). At the follow-up, approximately 80% of all patients had complaints of local neck symptoms. Pain at the extremes of neck motion and stiffness was the most frequent. The symptoms were mild and did not not usually have any major impact on return to work or leisure activities. Seventy-five percent of patients with incomplete cord lesions and useless muscle function improved to useful function. The patients had a statistically significant decrease of rotation (18%) and sidebending (18%) of the neck but normal flexion-extension motion when compared to the normal.

Plate fixation adds stability to two-level anterior fusion in the cervical spine: a randomized study using radiostereometry

Abstract This study evaluated whether addition of a cervical spine locking plate (CSLP) in two-level disc fusions improved the postoperative stability and reduced the time to healing. Radiostereometric analysis was used to obtain precise recordings of the three-dimensional motion between the fused vertebrae. Eighteen consecutive patients were operated on with excision of two adjacent cervical discs and anterior horseshoe grafting with autologous bone (Smith Robinson technique). Nine patients were randomized to stabilization with autologous bone grafting and CSLP plate fixation and nine patients to grafting without fixation. Clinical symptoms in terms of pain in the neck and the arm were analysed preoperatively and after 1 year using a visual analogue scale (VAS). The patients operated without a plate displayed increased rotations around the transverse axis, corresponding to the development of a kyphosis [mean value no plate/plate 14.4°/0.8° (repeated measure ANOVA: P < 0.01)]. The mean compression was 3.2 mm larger in patients operated without a plate (repeated measure ANOVA: P < 0.01). Patients operated without a plate had more arm pain at the 1-year follow up (P < 0.05, Mann-Whitney U test). The VAS score for neck pain did not differ significantly between the two groups. Plate fixation could not be demonstrated to increase the healing rate, promote more rapid fusion or influence the frequency of graft complications.

Outcome scores in degenerative cervical disc surgery

Abstract Forty-six consecutive patients with neck pain and arm radiculopathy were treated with anterior cervical discectomy and fusion. All patients had neurological symptoms corresponding to a herniated disc and/or spondylosis at one or two cervical levels, verified by magnetic resonance imaging. The patients were stabilized with an anterior graft and randomized to either fixation with a CSLP plate or no internal fixation. Preoperatively and 2 years postoperatively the patients filled in a questionnaire that included a modified Million Index, a modified Oswestry Index and the Zung Depression Scale. They were also asked to register their pain in the arm and in the neck on a vertical visual analogue scale (VAS). At the 2-year follow-up, an unbiased observer graded the patients’ clinical outcome using Odom’s criteria. A test-retest procedure was carried out to examine the questionnaire reproducibility. In the group that was operated at one level, there was no significant improvement in any of the scores. Nevertheless, 81% of the patients were satisfied with the outcome of the surgery. All scores improved in the group operated at two levels. The pain in the neck and arm, as measured on a VAS, decreased in both groups. The improvement in arm pain was significantly more pronounced in patients operated with a plate at two levels compared to those who were operated without a plate. At the 2-year follow-up, patients with an excellent or good result according to Odom’s criteria had a lower Million Index ¶(P < 0.0005), Oswestry Index (P < 0.0005), and Zung (P = 0.024) score, than the group classified as fair or poor. There was a significant correlation (P < 0.0001 for all scores) between the test and retest results. We conclude that the modified Million Index and Oswestry Index are clinically useful tools in the evaluation of outcome after degenerative cervical disc surgery. The clinical benefits of plate fixation were minimal. The outcome after surgery, measured with the Oswestry Index, Million Index and VAS for arm and neck pain, seems to correlate well with the classification of outcome by Odom.

One-level cervical spine fusion: A randomized study, with or without plate fixation, using radiostereometry in 27 patients

We randomized 27 consecutive patients undergoing 1-level cervical disc surgery to surgery with or without anterior plate fixation. The patients were studied with radiostereometry and clinically with visual analogue scores (VAS) for arm and neck pain. After 2 years, 1 patient had developed pseudoarthrosis, all other fusions were healed, but 1 patient showed substantial motions in the fusion area between the 1- and 2-year follow-ups. The 12 patients operated on without a plate had increased rotations around the transverse axis, corresponding to deformation towards kyphosis. Clinically, there was no difference in outcome between the two groups, as assessed by VAS. The use of an anterior plate in 1-level degenerative disc surgery in the cervical spine seems to prevent rotational deformation, without affecting the clinical outcome or fusion healing.

Forces and motions across the neck in patients treated with halo-vest.

A prospective study of the sagittal plane motion of the cervical spine, stabilized with a halo-vest was performed in 31 consecutive patients with unstable cervical spine injuries. Motion was measured in lateral radiograms taken with the patient in different positions and while performing various exercises. The extreme angle in extension and flexion in each motion segment, in any of the exercises, was measured and the sum of this maximal motion in each segment, between occiput and C6, was noted (maximal cervical motion). Distraction-compression forces across the neck were studied simultaneously with the motion study in the last 20 patients of the series. Strain gauges were mounted on the two vertical rods of the halo-vest and the forces were correlated to the motion of the spine. We found a mean maximal cervical motion of 51 degrees (about 70% of the normal motion). The halo-vest restricted the motion the most below C2 and the least above C2. In the supine position, all patients had a distraction force across the neck (mean: 51 N) that decreased in some exercises (eg, sitting, standing) and increased in others (eg, arm lifting, shoulder shrugging). Both the motion and the force varied widely between different types of exercises. There was a maximal variation of 175 N between the exercises. A positive correlation was found (r = 0.8) between the distraction force in the supine position and the maximal cervical motion. No significant differences of motion in the cervical spine were found between the rehabilitation exercises and common activities of daily living.

Surgery versus nonsurgical treatment of cervical radiculopathy : A prospective, randomized study comparing surgery plus physiotherapy with physiotherapy alone with a 2-year follow-up

Study Design. Prospective randomized controlled trial. Objective. To study the outcome of anterior cervical decompression and fusion combined with a structured physiotherapy program compared with the same physiotherapy program alone for patients with cervical radiculopathy. Summary of Background Data. Knowledge concerning the effects of interventions for patients with cervical radiculopathy is scarce due to a lack of randomized studies. Methods. Sixty-three patients were randomized to surgery with postoperative physiotherapy (n = 31) or physiotherapy alone (n = 32). The surgical group was treated with anterior cervical decompression and fusion. The physiotherapy program included general/specific exercises and pain-coping strategies. The outcome measures were disability (Neck Disability Index), neck and arm pain intensity (visual analogue scale), and the patients global assessment. Patients were followed for 24 months. Results. The result from the repeated-measures analysis of variance showed no significant between-group difference for Neck Disability Index (P = 0.23). For neck pain intensity, the repeated-measures analysis of variance showed a significant between-group difference during the study period in favor of the surgical group (P = 0.039). For arm pain intensity, no significant between-group differences were found according to the repeated-measures analysis of variance (P = 0.580). Eighty-seven percent of the patients in the surgical group rated their symptoms as “better/much better” at the 12-month follow-up compared with 62% in the nonsurgical group (P < 0.05). At 24 months, the corresponding figures were 81% and 69% (P = 0.28). The difference was significant only at the 12-month follow-up in favor of the surgical group. Significant reduction in Neck Disability Index, neck pain, and arm pain compared with baseline was seen in both groups (P < 0.001). Conclusion. In this prospective, randomized study of patients with cervical radiculopathy, it was shown that surgery with physiotherapy resulted in a more rapid improvement during the first postoperative year, with significantly greater improvement in neck pain and the patients global assessment than physiotherapy alone, but the differences between the groups decreased after 2 years. Structured physiotherapy should be tried before surgery is chosen. Level of Evidence: 2