Fibrillar collagen-biphasic calcium phosphate composite as a bone graft substitute for spinal fusion.

The osteoconductive capacity of fibrillar collagen-biphasic calcium phosphate composition was compared to autogenous bone in a canine spinal fusion model. All animals underwent a standard intervertebral body fusion (L2-L4) with rigid internal fixation and received either autogenous bone alone or a mixture of the ceramic and autogenous bone (3:1) as the graft material. Animals were followed for 12 months and the quality of fusion in each animal assessed by biomechanical testing and histological analysis. The fused L2-L4 segment of each dog was embedded in bone cement and mounted in a specially designed mechanical tester for testing in flexion, extension, and side bending. Overall, the mean rigidity of the fusion mass was not significantly different between the two groups [10.5 +/- 4.1 (SD) for autogenous bone vs. 11.3 +/- 1.7 for the ceramic plus autogenous bone, p greater than 0.05]. Similar findings were obtained for mean bending moment, compressive load, angular deformation, and energy absorbed for the two groups. Histological analysis was performed on transverse nondecalcified specimens. Quantitation of bone ingrowth using back-scattered electron imaging disclosed no significant differences in the amount of new bone formed at the graft site between autogenous bone and the ceramic plus autogenous bone recipients (23.4 +/- 10% vs. 25.8 +/- 8.8%) when correction for the autogenous bone volumes was performed. Light microscopic analysis of toluidine blue-stained transverse sections demonstrated new bone growth around and through the ceramic bone graft material. These results suggest that use of a collagen-biphasic calcium phosphate ceramic and autogenous bone mixture (3:1) provides a suitable osteoconductive alternative to the use of autogenous bone and results in the formation of a mechanically competent fusion mass not significantly different from that obtained with autogenous bone alone.

The role of anterior lumbar fusion for internal disc disruption.

Internal disc disruption is a syndrome of traumatically induced low-back pain arising from the intervertebral disc. The diagnosis is confirmed by abnormal discography with concordant pain reproduction at the affected level or levels. Thirty-four patients with internal disc disruption at one level were followed for an average of 29 months. Eighteen (53%) underwent anterior lumbar fusion at the L4-5 disc, 11 (32%) at the L5-S1 disc and the remainder at the L3-4 or L2-3 disc. Bank bone was used in all but seven patients for interbody fusion. Treatment was judged a success by the patient returning to work or normal activities and requiring either no medications or an antiinflammatory drug only. By the above criteria 25 patients (74%) had successful outcome of treatment. The average time to return to work or normal activities was 6.1 months. The overall union rate was 73% with an average time to union of approximately 12 months. Complications consisted of graft extrusion requiring revision and retrograde ejaculation. These occurred in one patient and were the only complications in the series. We concluded that disc excision and anterior interbody fusion is an effective treatment for internal disc disruption.

Segmental instability. Rationale for treatment.

Segmental instability, secondary to spinal degeneration, is a controversial topic. Based on current clinical, radiographic, and biomechanical considerations, this condition is classified as axial rotational, translational, retrolisthetic, and postsurgical instability syndromes. Each of these conditions would be expected, if untreated, to progress to a fixed deformity in which the clinical symptoms of spinal stenosis would predominate. The classification of these four types of instability suggests a need for specifically tailored fusion techniques in those patients who fail to respond to conservative treatment. Antitorsion facet fusion is suggested for axial rotatory instabilities; anterior (or posterior) interbody fusion for translational instabilities; and fusion in flexion (Knodt rods or facet fusion) for retrolisthetic instabilities. Post-surgical instability syndromes require carefully selected approaches based on the overall pathology. Application of specific fusion techniques, in carefully selected patients, may improve the currently unacceptable low rate of success from such operations.

Magnetic resonance imaging of the lumbar spine with CT correlation.

The results of magnetic resonance (MR) imaging and computed tomography (CT) in 18 patients with known degenerative disk disease of the lumbar spine were compared. In 60 intervertebral disk levels studied, there were 17 disks with degeneration and disk bulge, and 15 herniated disks. Final diagnoses were based on several factors, with surgical confirmation in five patients. There was good correlation between the two methods at 51 of the 60 levels studied. However, there were major discrepancies in interpretation at nine intervertebral disk levels. These included three false-positive MR imaging interpretations of a herniated disk and one false-negative herniated disk on MR imaging. MR imaging detected one case of disk herniation that was missed prospectively on CT. There were also four presumed degenerated disks seen on MR scans that appeared normal on CT. The conus medullaris was imaged in 16 of 18 patients. The sagittal view proved best for demonstrating both disk abnormality and the conus medullaris. The transaxial view was sometimes helpful in localizing a disk herniation, but partial-volume averaging in the 7-mm slice thickness limited its usefulness. There were five disk herniations that could not be accurately localized on the MR scan. MR imaging proved more sensitive than CT in detecting early disk disease, which appeared as decreased signal intensity within the disk. In three postoperative cases, MR imaging was better able to distinguish between recurrent disk herniation and postoperative scar formation. CT, on the other hand, was more specific in distinguishing herniated disk from disk bulge and proved far superior to MR imaging in localizing disk herniation.(ABSTRACT TRUNCATED AT 250 WORDS)

Conservative care of the lumbar spine in the elderly.

This diagnostic and treatment guide outlines a practical, clinical approach to the geriatric patient with lumbar spine pain. There is considerable academic debate on much of this, and it is omitted here to avoid confusion. However, I emphasize that this conceptualization is only one approach to what can frequently be a vexing problem, and does not imply that differences are incorrect.

When to operate and what to operate upon.

It is apparent that the results of spinal surgery are less than optimal. The three major causes appear to be as follows: Patient selection. There are some patients who, owing to psychological change or secondary gain, are unable to respond to correction of a spinal problem. This is probably a very small percentage of the 25 to 35 per cent failure rate listed in the literature. Many of these patients have had the wrong operation for an unknown structural diagnosis. It is too tempting and easy for the spinal surgeon to blame poor results on the psyche. Structural diagnosis. It has been 40 years since Dandy published a report on "the hidden disc," but the world of spinal surgery still has not recovered from it. Poor Dandy is also credited with introduction of the method of shaking the spinous process as a test for instability and hence fusion. It would seem obvious that any disc surgery based on a premise of exploration for a hidden problem is antiquated in the day of the CT scan. One should be further chagrined by decision making for fusion based on shaking the spine with a towel clip. It would defy any spinal surgeon to define in rational terms how much observed motion is "abnormal." Until a structural diagnosis is made on the basis of clinical and laboratory testing, there is no indication for surgery. This is the single most important factor in spinal surgery. The success rate will not change until this function is universally recognized. Proper operation. There is little room, in modern spinal surgery, for the surgeon who is a "one trick pony." Uniform application of an operative technique to a variety of deforming forces will result in a high failure rate. It is the duty of the spinal surgeon to have all the techniques available and be able to apply them with precision and skill. Specific surgical response must be made to a specific structural diagnosis. The foregoing three principles should greatly enhance surgical results.

A motivational scoring system for outcome prediction with spinal pain rehabilitation patients.

The aim of this study is to demonstrate an effective method of testing using the Sixteen Personality Factor Questionnaire (16 PF) along with the Minnesota Multiphasic Personality Inventory (MMPI) to predict outcome criteria in a spinal pain clinic. Using an objective system of criteria for patient achievement, including goals attained, pain estimates, psychological adjustment, medication reduction, and physical function, a quantitative method of scoring was employed to find success and failure. Using appropriately constructed testing methods, a very high level of predictability of outcome is now available. The combined use of the 16 PF and the MMPI can be relied upon to predict effective results in a spinal pain program with considerable confidence.

Water soluble myelography.

Our experience with 451 water soluble myelograms has been presented. We feel that the advantages exceed the disadvantages and that a water soluble medium is essential for a truly diagnostic myelographic study.