Lumbar arthrodesis for the treatment of back pain

Course of Modic 1 six months after lumbar posterior osteosynthesis

STUDY DESIGN

A prospective study was conducted to investigate the outcome of the Modic Type 1 inflammatory signal in magnetic resonance imaging (MRI) in 17 patients with chronic low back pain 6 months after instrumented posterior lumbar arthrodesis.

OBJECTIVE

To assess the course of the inflammatory signal after stabilization of a painful intervertebral segment by posterior instrumentation alone visualized on MRI systematically performed 6 months after the operation.

SUMMARY OF BACKGROUND DATA

In 1988, Modic and colleagues described three degenerative stages of vertebral endplates and subchondral bone. The inflammatory stage, or Stage 1, is correlated with substantial functional disability. According to these authors, Stage 1 lesions naturally transform into Stage 2, the fatty stage. In the literature, patients with Modic 1 signal tend to have good results after arthrodesis, better than those with Modic 2 lesions.

METHODS

This study included 17 patients (average age, 46 years) who had experienced chronic low back pain more than 1 year and showed Modic 1 changes in MRI and disc narrowing on plain radiographs. Every patient underwent posterior screw-rod osteosynthesis and posterolateral arthrodesis. Disc disease had occurred subsequently to discectomy (n = 7), rapidly destructive disc disease (n = 5), or spondylolisthesis resulting from spondylolysis (n = 5). Clinical results were assessed according to a visual analog scale for pain, a functional disability score for the evaluation of patients with low back pain (Eiffel), and the validated French version of the self-administered Dallas quality-of-life test (DRAD).

RESULTS

Systematic MRI at 6 months showed transformation from Modic 1 to Modic 0 (normal endplate signal) in 4 patients and transformation from Modic 1 to Modic 2 in the remaining 13 patients. Clinical evaluation was performed at 6 months (at the same time as the MRI) and at 1 year. In every patient, there was improvement in the visual analog score and the functional score, which remained stable at 1 year.

CONCLUSIONS

According to the literature, most Modic 1 lesions change to become Stage 2 lesions in 18 to 24 months. In this study, 17 patients with Modic Type 1 signal had changes after 6 months. It appears that posterior osteosynthesis combined with posterolateral arthrodesis accelerates the course of Modic 1 lesions, probably by correcting mechanical instability.

Histology of tissues within retrieved human titanium mesh cages

STUDY DESIGN

Histologic documentation of contents within retrieved, failed human titanium mesh cages.

OBJECTIVES

The purpose of this study is to describe the contents of a series of retrieved, clinically failed titanium mesh cages from human patients.

SUMMARY OF BACKGROUND DATA

The use of interbody fusion cages is gaining rapid acceptance, but there is little histologic documentation of tissue within retrieved cages.

METHODS

Eleven Titanium Surgical Mesh Cages (Harms; DePuy AcroMed, Raynham, MA) retrieved from 10 patients were histologically analyzed. Indications for cage retrieval included failed fusion or failed fusion with instrumentation failure. The cages had been in situ from 2 to 47 months. Histologic sections were reviewed qualitatively, and the approximate percent of area in the cage occupied by viable bone, necrotic bone, fibrocartilage, hyaline cartilage, fibrous tissue, and bone graft substitute was visually estimated. Particles of metal debris were estimated by a semiquantitative scoring system.

RESULTS

All cages except one showed evidence of vascular ingrowth and areas of histologically viable bone, representing incorporating bone graft. At least a few particles of debris were present in 9 of 11 cages. Fibrocartilage of probable intervertebral disc origin ranged from 0% to 70% of the available area. Several cages contained small seams of fibrocartilage connecting segments of bone in a pattern that suggested a response to motion.

CONCLUSIONS

Mean viable bone area within 11 retrieved, human titanium mesh cages was approximately 31%. Seams of fibrocartilage within the cages may represent tissue differentiation in response to bending or compressive load.

Intradiscal electrothermal treatment for chronic discogenic low back pain: prospective outcome study with a minimum 2-year follow-up

STUDY DESIGN

Prospective longitudinal study with a minimum 2-year follow-up.

OBJECTIVE

To assess the long-term outcome of a group of patients with chronic discogenic low back pain who had failed to improve with comprehensive nonoperative care and who were subsequently treated with intradiscal electrothermal therapy (IDET).

SUMMARY OF BACKGROUND DATA

Previous reports of patient outcomes at 1 year after IDET have demonstrated statistically significant improvement.

METHODS

The study group comprised 58 patients with chronic symptoms of more than 6 months who failed to improve with nonoperative care and subsequently underwent IDET. VAS pain scores, SF-36 scores, and sitting tolerance times were collected pretreatment and at 6, 12, and 24 months.

RESULTS

Mean duration of pre-IDET symptoms was 60.7 months. The minimum follow-up at data collection was 24 months. The study group (n = 58) demonstrated a significant improvement in pain as demonstrated by statistically significant improvement in VAS scores and bodily pain SF-36 scores. The IDET-treated group demonstrated a significant improvement in physical function as noted by statistically significant improvement in sitting tolerance times and physical function SF-36 scores. Bodily pain and physical function scores demonstrated significant improvement between the 1- and 2-year observation points. Additionally, quality of life improvement was demonstrated by a statistically significant improvement in all the SF-36 subscales.

CONCLUSIONS

A cohort of patients with chronic discogenic low back pain who had failed to improve with comprehensive nonoperative care demonstrated a statistically significant improvement in pain, physical function, and quality of life at 2 years after IDET.

Transverse process fusion with bovine anorganic bone

A biodegradable collagen membrane and bovine anorganic bone were studied in a rabbit spine fusion model. The bovine, anorganic bone is a nonantigenic, acellular clinical product used as a bone substitute for dento-alveolar applications. We reasoned this product with a collagen membrane could be useful for spine fusions. Our hypothesis was that bovine, anorganic bone, and a collagen membrane would promote spine fusion equivalent to an autogenous bone graft. To test the hypothesis, the transverse processes of the fourth and fifth lumbar vertebrae were decorticated in 30 rabbits divided equally among five groups. In one group, following decortication, no treatment was administered, whereas in the remaining four groups, treatments consisted of either autograft, collagen membrane, anorganic bone, or anorganic bone plus collagen membrane. Rabbits were euthanized 6 weeks after surgery, and the lumbar vertebrae were removed, radiographed, and processed for histology. The radiographs and histological sections were subjected to quantitative morphometric analyses and post hoc statistical testing (p < or = 0.05). We determined anorganic bone without a collagen membrane migrated into the soft tissues contiguous to the transverse processes. However, with a collagen membrane, the anorganic bone remained at the implant site, causing an osseous fusion of the transverse processes. Although the autograft promoted the greatest amount of new bone formation, significant transverse process fusion was accomplished with the anorganic bone and collagen membrane. Additional longer term studies are contemplated to validate feasibility of this clinical option, including a biomechanical component.

Anterior BAK instrumentation and fusion: complete versus partial discectomy

Beginning in January 1994, a prospective, clinical study was done comparing the effectiveness of complete anterior (Group 1) versus partial reamed channel discectomies (Group 2) in 100 consecutive patients who had anterior BAK instrumentation and fusion using autogenous iliac crest bone graft. At 2 or more years of followup, all patients in Group 1 who had complete operative disc removal achieved solid arthrodesis. There were no revision surgeries. However, in Group 2, there were seven patients who had a pseudarthrosis and an additional patient with early postoperative cage displacement, which resulted in eight patients in Group 2 requiring revision surgery. The differences in operative preparation of the disc space for BAK instrumentation surgery resulting in complications proved to be significant. The use of interbody titanium cages dramatically increases the biomechanical efficacy of anterior fusions. Original proponents of cages advocated removing a cylindrical channel of disc material using a drill. A prospective review of 100 patients who had complete versus partial discectomy revealed 14% of patients in Group 2 eventually had a pseudarthrosis develop.

Clinical and demographic prognostic indicators for human disc cell proliferation in vitro: pilot study

STUDY DESIGN

Human anulus cells were cultured under control and experimental conditions to study associations between proliferation and clinical-demographic features of subjects from which cells were obtained. Statistical multiple regression analyses were applied to develop mathematic models relating proliferation to age, gender, Thompson score (denoting stage of disc degeneration), and status (control donor [postmortem]; surgical patient).

OBJECTIVES

To identify the effect of donor characteristics on proliferative capacities of human disc cells.

SUMMARY OF BACKGROUND DATA

As therapeutic options for disc degeneration increase, novel biologic options are important future considerations. Little is known about the influence of clinical-demographic features on cell proliferation.

METHODS

Anulus cells were studied in two designs: 1) Cells from 12 individuals were grown in monolayer with 50 ng/mL interleukin growth factor-1 (IGF-I), 100 ng/mL insulin, or control conditions. 2) Cells from nine individuals were grown in three-dimensional culture with 10 ng/mL IGF-I or control conditions. Cell proliferation data and data on age, gender, Thompson score, and status were collected. Standard statistical analyses were used to develop correlation models.

RESULTS

Data from monolayer experiments produced significant models fitting proliferation in the presence of low serum, 50 ng/mL IGF-I, or insulin, with age, gender, Thompson score, and status (respective R2: 0.827, 0.680, 0.850). Three-dimensional cultures exposed to 10 ng/mL IGF-I resulted in proliferation that correlated in a significant negative manner with Thompson score (r = -0.798).

CONCLUSIONS

Clinical-demographic prognostic indicators may help predict levels of proliferation. Greater age, greater disc degeneration, female gender, and surgical derivation had deleterious effects on proliferation potential in this model.

Failure of external spinal skeletal fixation to improve predictability of lumbar arthrodesis

BACKGROUND

Whether lumbar arthrodesis can relieve isolated low-back pain in the absence of focal neurological findings or instability is unclear. The results of published studies are also inconsistent with regard to whether temporary back-pain relief with external spinal skeletal fixation can predict lasting back-pain relief after arthrodesis. This report presents the results, with regard to clinical benefit and complications, of more than 100 external spinal skeletal fixation procedures undertaken as a prelude to lumbar arthrodesis.

METHODS

The records of all patients who underwent external spinal skeletal fixation between 1989 and 1999 were reviewed with attention to perioperative complications, pain relief from the test procedure, the clinical benefit from a subsequent arthrodesis, and the functional status after the arthrodesis. Analyzed data included the frequency of neurological complications and infections and the benefit (Prolo score) after staged spinal arthrodesis in patients who underwent arthrodesis after temporarily experiencing pain relief with the test procedure.

RESULTS

A total of 103 external spinal skeletal fixation procedures were undertaken. Neurological complications occurred in two procedures (2%); one resulted in permanent sciatica. Infections occurred in five patients (5%). Sixty patients experienced pain relief during the external fixation test, but only twenty-seven of forty-nine patients who went on to have an arthrodesis and had sufficient follow-up reported that they were doing well at a minimum of one year later. In no case did the external spinal skeletal fixation procedure cause a permanent increase in low-back pain.

CONCLUSIONS

On the basis of this analysis, external spinal skeletal fixation should not be used as a predictor of pain relief after lumbar arthrodesis.

The vascular anatomy anterior to the L5-S1 disk space

STUDY DESIGN

Dissection of 37 human cadavers was performed to assess the variability in the vascular anatomy anterior to the L5-S1 disc space.

OBJECTIVES

To determine the variability of the anterior vascular anatomy at the L5-S1 disc space, and to assess its reliability as an anatomic landmark for the placement of anterior interbody fusion devices.

SUMMARY OF BACKGROUND DATA

Although multiple studies have defined both the lumbar spinal anatomy and the anatomy of the great vessels, the relation of the great vessels to the anterior L5-S1 disc space has not been quantified directly.

METHODS

This study investigated 35 human cadavers (17 males and 18 females). The anterior L5-S1 disc space and great vessel bifurcation were exposed through a transabdominal approach. Two independent observers each obtained 10 measurements in each specimen.

RESULTS

The middle sacral artery was present in 100% of the specimens, averaging 2.5 mm in width. Its location in relation to the midline was quite variable, with a range greater than 2 cm in both the top and bottom of the disc. The distance from the bifurcation to the top of the L5-S1 disc averaged 18 mm (range, 7-36 mm). The total width between the left common iliac vein and the right common iliac artery averaged 33.5 mm (range, 12-50 mm).

CONCLUSIONS

The middle sacral artery, present in 100% of the specimens, is a poor anatomic landmark for locating the midline at L5-S1. Because the average space available between the left common iliac vein and the right common iliac artery is 33.5 mm, and because the left common iliac vein averages only 12 mm from midline, the surgeon must be prepared to mobilize the local vasculature in most cases to expose the L5-S1 disc space adequately.

Functional outcomes of instrumented posterior lumbar interbody fusion in active-duty US servicemen: a comparison with nonoperative management

BACKGROUND CONTEXT

The existing literature lacks a functional outcome study addressing instrumented posterior lumbar fusion surgery in physically active patients. Furthermore, results of operative versus nonoperative treatment in these patients are not clear.

PURPOSE

To evaluate patient-assessed function, pain, and satisfaction and military job performance between servicemen treated operatively and nonoperatively.

STUDY DESIGN/SETTING

This is a nonrandomized analysis of consecutive active-duty military servicemen treated either operatively or nonoperatively for chronic back pain and single-level lumbar disc degeneration with emphasis on functional outcomes.

PATIENT SAMPLE

Active-duty US servicemen with chronic low back pain. OUTCOME MEASURES/METHODS: Twenty-nine consecutive active-duty US servicemen were treated for chronic back pain and single-level lumbar disc degeneration by the same surgeon at a military spine facility. Fifteen were treated with instrumented posterior lumbar interbody fusion (PLIF), and 14 refused surgery and chose to be treated nonoperatively with spinal extensor muscle-strengthening exercise, medications, and restricted duty. The average follow-up time was 14 months (range, 6 to 24 months). All servicemen completed a functional outcome questionnaire American Academy of Orthopedic Surgeons/Scoliosis Research Society (AAOS/SRS) with emphasis on pre- and posttreatment function, pain, and satisfaction. The two groups were also compared using military job performance parameters.

RESULTS

Four of 14 (28%) of the servicemen treated nonoperatively ultimately received a disability discharge from the military for back pain, another 5 of 14 (36%) remained on permanent duty-restriction profiles, and only 5 of 14 (36%) returned to full, unrestricted military duty. In the PLIF group, 12 of 15 soldiers (80%) were able to return to full duty, only 3 of 15 (20%) remained on permanent restrictive duty-limitation profiles, and 0 of 15 (0%) received a disability discharge from the military for back pain. Twelve of 15 (80%) of the PLIF group and 8 of 14 (57%) of the group treated nonoperatively were physically able to complete the posttreatment physical fitness test. No difference was observed between premorbid and posttreatment physical training (PT) test scores in either group. However, scores for patient-assessed posttreatment pain, function, and satisfaction were significantly higher in the PLIF group. Soldiers who were able to return to full military duty did so at an average of 2 months for the group treated nonoperatively (n = 5) and 4 months for the PLIF group (n = 12). Complications in the PLIF group included dural tear (n = 2), unilateral transient lower extremity paresthesia (n = 1), and wound seroma requiring reoperation (n = 1).

CONCLUSIONS

In this nonrandomized study of 29 active-duty US servicemen with chronic low back pain and single-level lumbar disc degeneration, instrumented PLIF surgery was associated with a high rate of return to full military duty. Servicemen treated with this technique were less likely to receive a back pain disability discharge or a permanent physical limitation profile when compared with servicemen who chose to be treated nonoperatively. Outcomes with respect to postreatment pain, function, and satisfaction were higher in patients treated with instrumented PLIF and were excellent in servicemen who were able to return to full duty regardless of treatment.

Low Back Pain

Low back problems are extremely common. In the United States, it is estimated that 15% to 20% of the population, and approximately half of working-age adults, admit to back pain each year. Low back pain (LBP) is a symptom and not a specific disease, and there are a large number of potential causes. The vast majority of patients with LBP have a musculoskeletal cause. Ninety percent of patients with acute low back problems recover within a month with very conservative treatment. Because of the multiple possible causes in the musculoskeletal category, and because of the self-limited nature of most patients' pain, only about 15% of patients can be given a specific diagnosis to explain their LBP. Although 90% of patients with LBP have self-limited disease, recurrent attacks of pain are common, and approximately 10% of patients develop chronic LBP. In general, LBP is over-evaluated and over-treated, which results in wasted money and medical resources, and often yields inferior clinical outcomes. The physician's job, when evaluating a patient with acute LBP, is to look for "red flags"--symptoms and signs that should prompt additional evaluation and treatment. Without "red flag" conditions, LBP should be treated with "comfort control" measures only. These measures include activity modification and the use of simple analgesics. Manipulation therapy may be helpful in the short term (within the first month of onset), although other physical therapies are more helpful beyond 1 month from onset. Surgical intervention on the spine for patients without tumors, infection, and fracture should be reserved for patients with progressive or unrelenting compression of one or more lumbosacral nerve roots by a herniated intervertebral disk. Neurologists should be involved in the evaluation and treatment of patients with LBP, because many of the worrisome underlying conditions affect the nerve roots, and most of the surgical interventions are based on documentation of the presence of nerve root impingement. Neurologists can determine if these indications are present, and do not have a vested interest in recommending costly procedures.

Spine fusion for discogenic low back pain: outcomes in patients treated with or without pulsed electromagnetic field stimulation

Sixty-one randomly selected patients who underwent lumbar fusion surgeries for discogenic low back pain between 1987 and 1994 were retrospectively studied. All patients had failed to respond to preoperative conservative treatments. Forty-two patients received adjunctive therapy with pulsed electromagnetic field (PEMF) stimulation, and 19 patients received no electrical stimulation of any kind. Average follow-up time was 15.6 months postoperatively. Fusion succeeded in 97.6% of the PEMF group and in 52.6% of the unstimulated group (P < .001). The observed agreement between clinical and radiographic outcome was 75%. The use of PEMF stimulation enhances bony bridging in lumbar spinal fusions. Successful fusion underlies a good clinical outcome in patients with discogenic low back pain.

Epidemiology, etiology, diagnostic evaluation, and treatment of low back pain

Low back pain is a common medical problem but has decreased in frequency in the occupational setting over the past decade. The weather affects low back pain but to a minor degree. Physical factors, as well as job satisfaction, play a role in the development and perpetuation of low back pain. In contradistinction to previous measurements, intradiscal pressure has been determined in vivo to be greater in the standing than the sitting position. Adenovirus-mediated gene transfer to nucleus pulposus cells may be the initial stage of a new form of therapy for degenerative disc disease. Bed rest is not more helpful than activity as tolerated for the treatment of sciatica. The outcome of spinal stenosis surgery is more closely associated with the patient's perception of improvement than with the degree of canal narrowing.