Charles D. Ray

Threaded titanium cages for lumbar interbody fusions.

Study Design. This study evaluated safety, fusion success rate, and clinical outcome of a new lumbar interbody hollow, threaded titanium fusion cage in a multicenter, prospective 236‐case program adhering to a United States Food and Drug Administration Investigational Device Exemption‐controlled protocol. Objectives. The results were evaluated to demonstrate the safety and effectiveness of this new method to achieve solid lumbar interbody fusions. Summary of Background Data. Interbody fusions have certain distinct mechanical advantages over lateral or posterolateral ones. Autologous, cancellous bone is the preferred graft material, but is too soft to maintain the space during fusion without mechanical support. Various methods have been used in the past to maintain the graft integrity during fusion development. Methods. An initial pilot study began on 10 patients (followed for 84 months, average 80 months). Two years after that investigation started, the multicenter United States Food and Drug Administration Investigational Device Exemption study began, with cases followed for 28–46 months (average, 32). Ninety‐six percent of the Investigational Device Exemption study cases had severe, disabling back pain; in addition, 74% had major anular degeneration; 57% had herniations; 21% had osteophytes; and 43% had disc height reduced by greater than 10%. Forty‐five percent of cases had previous spinal surgeries, and none were posterior lumbar interbody fusions. Titanium fusion cage pairs were screwed into bored and threaded, parallel intradiscal holes, and 3–8 ml autologous cancellous bone was packed inside each. Fusion success was judged by absence of motion on flexion‐extension radiographs, absence of bone halo around the implants, and maintenance of visible bone inside the cages on Ferguson view radiographs. Results. Segments fused rapidly; the pilot study cases fused at 10 (91%) of 11 levels, with a reported 80% average clinical improvement. Ninety‐six percent of the 208 2‐year follow‐up Investigational Device Exemption cases had fusion, and the Prolo socioeconomic/functional improvement scale showed: 40% excellent, 25% good, 21% fair, and 14% poor results. Less than 1% of Investigational Device Exemption cases had complications that persisted beyond the average 5 days of hospitalization, and none were serious. Conclusions. The Ray titanium fusion cage (Surgical Dynamics, Norwalk, CT) implant method has been found to be an effective, rapid, safe procedure for lumbar spine fusions, demonstrating a high fusion rate and clinical success with rare, serious, or permanent complications.

Artificial nucleus replacement: clinical experience.

The prosthetic disc nucleus is designed to help treat patients suffering from degenerative disc disease. The device consists of a hydrogel core that is encased in a polyethylene jacket and is intended to restore disc height while permitting normal range of motion. Clinical trials for the prosthetic disc nucleus were first conducted in 1996, and the device was found to be effective in most of the patients that were implanted. Additional trials in 1997–1998 were less successful, with 38% of patients requiring revision surgery because of device migration. Subsequent changes were made to device shapes and to the surgical protocol to facilitate implantation, thereby eliminating the high device migration rates. Following these modifications, the success rate for the device has improved significantly. Clinical data show excellent results with marked improvements in Oswestry and Prolo scores. Overall, disc height measurements have been well maintained within normal physiologic ranges. The prosthetic disc nucleus device is currently undergoing clinical trials in Canada, and an IDE application to the Food and Drug Administration was expected in the fall, 2001.

Symposium : A Critical Discrepancy-A Criteria of Successful Arthrodesis Following Interbody Spinal Fusions

Question: What should the radiographic criteria be for a successful arthrodesis for lumbar interbody fusion cages? The definition of successful arthrodesis following anterior lumbar fusion is controversial. The comparison of different surgical arthrodesis techniques, interbody prostheses, and bone g

Threaded fusion cages for lumbar interbody fusions. An economic comparison with 360 degrees fusions.

Study Design. This study compared the surgical and hospitalization costs, operating times, and blood loss attributable to lumbar interbody fusions at one and two lumbar levels by the use of two device systems: 1) the Ray Threaded Fusion Cage, and 2) an anteroposterior interbody technique with pedicle screw and rod stabilization (360° fusion). The clinical efficacy and complication rate of each method were similar. Objectives. Data were analyzed to compare the newer threaded fusion cage method with the well established 360° technique. Summary of Background Data. Interbody bone grafts are a proven concept to obtain solid spinal fusions. A variety of mechanical means are used to stabilize the graft material during the fusion growth and have been shown to be important in facilitating both the rate and ultimate quality of the fusion. Methods. In a cohort of 50 prospectively selected patients having severe, disabling back pain with discal degeneration, 25 received Ray Threaded Fusion Cages and 25 had anteroposterior interbody fusion procedures using pedicle screws (360° technique) over the period 1991 to 1995. All implants were performed by the same surgeon in the same hospital. All fusions were judged solid by established radiologic criteria. Cost comparisons were made from pertinent medical records using inflation‐corrected 1995 U.S. dollars. Results. The average combined (surgeon, hospital, anesthesiologist) costs attributed to one‐level threaded fusion cage procedures were

Computed tomographic scanning and the lumbar spine. Part II: Clinical considerations.

25,171, and

New kneeling attachment and cushioned face rest for spinal surgery.

41,813 to equivalent 360° procedures, a difference of 40% or

Special article: Clinical Neurosurgery as It Relates to the Lumbar Spine: What It Does versus What It Says

16,642. Costs for two‐level cases were

Bone Impactors: New Instruments for Spinal Decompression

33,113 and

Disposable ventricular catheter.

47,320, respectively, differing by 30% or

Burr-hole ring-cap and electrode anchoring device Technical note

14,207. The average saving through preferential use of the threaded fusion cage was