Solis cage (PEEK) for anterior cervical fusion: preliminary radiological results with emphasis on fusion and subsidence.

BACKGROUND CONTEXT: Recent literature has raised some apprehensions with regard to the usage of cervical cages. PURPOSE: Radiological review of cases performed at our institution with a novel cage made of polyetheretherketone (PEEK). STUDY DESIGN: Retrospective study. METHODS: A retrospective review of the first 15 consecutive cases of single-level anterior cervical interbody fusion using the Solis cage (PEEK material) for cervical spondylotic radiculopathy or myelopathy was performed. The follow-up ranged from 12 to 35 months (average 18 months). Anteroposterior and lateral radiographs were taken immediately after the surgery and at intervals of 3, 6, 12, and 24 months after surgery. Anterior disc height (ADH), posterior disc height (PDH), interbody height ratio (IBHR), distance between the posterior margin of the cage and the posterior wall of the vertebral body (D-CPW), and interbody angle (IBA) were measured on the lateral radiographs and compared. Fusion was assessed by examining for trabecular continuity, bridging of bone across the disc space, and sclerosis at the vertebral end plates on both sides. The parameters assessed were time for fusion, subsidence, segmental sagittal alignment of the operated segment, and presence/absence of migration of the cage. Data were analyzed using the Mann-Whitney nonparametric test. RESULTS: Fusion was evident at 3-6 months postsurgery in all cases except one (93.33% fusion rate at 6 months). At the last follow-up, fusion was maintained in all cases. The immediate postoperative ADH and PDH was significantly greater than the respective preoperative values and was maintained at the last follow-up though there was a significant amount of subsidence when the follow-up radiographs were compared with the immediate postoperative X-rays. The immediate postoperative IBHR was significantly greater than the preoperative IBHR, and was maintained at the last follow-up, but not statistically significant. The immediate postoperative IBA (lordotic angle) was greater than the preoperative IBA but was not statistically significant. The IBA at the last follow-up was lesser than the preoperative value but with no statistical significance. The IBA measured at the last follow-up was less than the value at the immediate postoperative period, but not statistically significant. There was no migration or extrusion of the cage at latest follow-up. CONCLUSIONS: The high fusion rate, low subsidence, stability provided by the cage, and facilitation of radiological assessment are the result of the physical properties of the PEEK material as well as the design of the cage.

Insertion torque profile during pedicle screw insertion of the thoracic spine with and without violation of the pedicle wall: comparison between cylindrical and conical designs.

STUDY DESIGN: Biomechanical study in human cadaveric thoracic spines. OBJECTIVE: To compare the insertion torque profile of cylindrical and conical screws with normal insertion tract, and with violation of the pedicle. SUMMARY OF BACKGROUND DATA: Previous studies revealed higher insertion torque for conical screws. No study has investigated the torque profile of both screws when there is violation of the pedicle. METHODS: The pedicle screws were inserted intrapedicularly (Type 1), violating the lateral cortex of the pedicle (Type 2), and violating the medial cortex of the pedicle (Type 3). Type 2 screws were further subdivided into those having contact with the lateral vertebral body (2a) and those without (2b). Type 3 screws were subdivided into those having contact with the medial pedicle wall (3a) and without (3b). RESULTS.: During initial insertion, the torque increased as they penetrated into the pedicles. With violation of the lateral cortex of the pedicle, insertion torque for the cylindrical screw decreased as the screw advanced anteriorly out of the pedicle. The insertion torque for the conical screw continued to increase at a constant rate after violation of the lateral cortex. With medial breach of the pedicle wall, torque profile of the conical screws remained the same as those inserted in the normal trajectory. There was a decline in the insertion torque for the cylindrical screws when medial violation of the pedicle wall occurred, the decrease being greater for Type 3b as compared with Type 3a screws. CONCLUSIONS: Surgeons may be unable to perceive the occurrence of medial or lateral breach of the cortex when inserting a conical screw. Surgeons inserting cylindrical screws with Type 3a violation may not be able to perceive a significant decrease in torque.

The effect of previous low back surgery on general health status: results from the National Spine Network initial visit survey of patients with low back pain.

STUDY DESIGN: A cross-sectional study on 18,325 patients with back pain enrolled at first visit in the National Spine Network (NSN) database from January 1998 to April 2000. OBJECTIVES: To examine whether patients who had previous low back surgeries had poorer general health status than patients with no surgery. SUMMARY OF BACKGROUND DATA: Several studies have described the role of psychological abnormalities in patients with chronic low back pain. Some of these patients have had previous spinal surgeries performed. No study has examined the effects of previous low back surgery on the general health status. METHODS: The Short Form Health Survey 36 was administered to the initial visit NSN patients. Of the 18,325 patients enrolled, 3,632 had previous low back surgeries. RESULTS: Patients who had previous lumbar surgeries fared significantly poorly in all 10 scores of the SF-36 health survey, even after adjustment for confounding factors. Among these patients, decompression achieved significantly higher scores for General Health, Role-Physical, and Mental Component Summary scales. Patients who had decompression as their most recent surgery had higher scores for General Health, Role-Physical, Role-Emotional, and Mental Component Summary scales, when compared to those who had other surgeries. Patients who had instrumentation as their most recent surgery had higher scores for Bodily Pain and Physical Component Summary scores. There is a positive correlation between time since last surgery and the SF-36 outcomes. CONCLUSIONS: Previous back surgery is associated with significantly worse general health status than those without surgery. Among patients who had previous surgeries, decompression seems to exert better effects on SF-36 health status. There is a positive correlation between time since last surgery and the SF-36 outcomes, although the SF-36 scores are significantly lower than those without previous surgery.

Do autologous growth factors enhance transforaminal lumbar interbody fusion?

Pseudarthrosis remains a significant problem in spinal fusion. The objective of our study was to investigate the effects of autologous growth factors (AGF) in instrumented transforaminal lumbar interbody spinal fusion (TLIF). A prospective review was carried out of 23 patients who underwent TLIF with application of AGF, with a minimum 2-year follow-up. Comparison with our historical cohort (without AGF application) was performed. Mean age at surgery was 44.3 years in the AGF treatment group. Twelve had a positive smoking history. Fourteen had undergone previous spinal surgeries. Thirteen received one-level fusions and ten received two-level fusions. The radiographic results showed a fusion rate of 100% in one-level fusions and 90% in two-level fusions. There was no significant difference in pseudarthrosis rates between the AGF treatment group and historical cohort. Excluding the cases with pseudarthrosis, there was faster bony healing in patients who had been treated with AGF application. This study indicates that although AGF may demonstrate faster fusions, it does not result in an overall increase in spinal fusion rates. Further studies are needed before AGF can routinely be used as an adjunct in spinal fusion.

Complications of multilevel cervical corpectomies and reconstruction with titanium cages and anterior plating.

The ideal surgical treatment of multilevel cervical spondylosis remains unclear. This study analyzed the complications in using titanium cages and plating to reconstruct multilevel cervical corpectomies. This was a retrospective analysis of 21 consecutive patients who had multilevel cervical corpectomies and reconstruction with titanium cages and anterior plating. Sixteen had 2-level, one had 2.5-level, three had 3-level, and one had 3.5-level corpectomies. All had reconstruction with titanium cages and anterior plating. Thirty-three percent of the patients developed complications. Radiographs revealed bony consolidation in 95% of patients. Reconstructing multilevel cervical corpectomies with titanium cages and plating is associated with complications. Advantages include rigid immobilization and the avoidance of iliac crest bone graft harvesting. Major complications are largely the result of failures of the cage and plate construct, especially in patients with osteopenic bone. Supplemental posterior stabilization may be considered for cases with spasticity or greater than 2-level corpectomies with profound osteoporosis.

Do worker's compensation patients with neck pain have lower SF-36 scores?

Poorer outcomes of treatment are reported in patients with spinal disorders who receive worker's compensation. The reason for their suboptimal outcomes is unclear. No study has examined the relationship between worker's compensation and SF-36 health status of patients with neck pain. The aim of our study was to compare the self-perceived health status of patients with neck pain receiving worker's compensation, with that of patients not receiving worker's compensation. A cross-sectional study was conducted on 2356 patients with neck pain who were evaluated at the 27 centers comprising the National Spine Network, between January 1998 and April 2000. The outcome measures used were the eight individual and two component scores of the SF-36 health survey. Of the 2356 patients, 171 (7%) were receiving worker's compensation. Bivariate analyses revealed seven individual scores (except General Health) and two summary scores of the SF-36 were significantly lower in patients receiving worker's compensation. After controlling for confounding covariates, worker's compensation status was a significant predictor of lower SF-36 scores for Physical Functioning ( P<0.05). The results of this study indicate that worker's compensation status is associated with poorer Physical Functioning in patients presenting with neck pain. Another significant finding of the study is that confounding factors can exert major effects on the SF-36 scores obtained on normal validated instruments.

Better treatment of vertebral osteomyelitis using posterior stabilization and titanium mesh cages.

There is no scientific consensus on the role of posterior instrumentation in vertebral osteomyelitis. No study has examined the use of titanium cages to reconstruct the anterior column of the spine with vertebral osteomyelitis. Here the authors evaluated the efficacy of using titanium mesh cages anteriorly and posterior instrumentation after anterior debridement in the surgical treatment of vertebral osteomyelitis. In one center, 21 consecutive patients had surgery for vertebral osteomyelitis. The mean follow-up time was 67 months (range, 24 to 120 months). Ten patients received supplemental posterior instrumentation. Five patients had reconstruction of the anterior column with titanium cages. Greater improvement in sagittal alignment was noted for patients with cages implanted (p = 0.0009) and for those with posterior instrumentation (p = 0.005). Patients who received cages had greater (p = 0.0006) correction of their coronal alignment than did those patients without cages. A trend toward fewer postoperative complications emerged for patients who had posterior stabilization or titanium cages. These results support the use of posterior stabilization and titanium cages in the surgical treatment of vertebral osteomyelitis.