Leah Y. Carreon

Minimum clinically important difference in lumbar spine surgery patients: a choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form 36, and Pain Scales

BACKGROUND CONTEXT The impact of lumbar spinal surgery is commonly evaluated with three patient-reported outcome measures: Oswestry Disability Index (ODI), the physical component summary (PCS) of the Short Form of the Medical Outcomes Study (SF-36), and pain scales. A minimum clinically important difference (MCID) is a threshold used to measure the effect of clinical treatments. Variable threshold values have been proposed as MCID for those instruments despite a lack of agreement on the optimal MCID calculation method. PURPOSE This study has three purposes. First, to illustrate the range of values obtained by common anchor-based and distribution-based methods to calculate MCID. Second, to determine a statistically sound and clinically meaningful MCID for ODI, PCS, back pain scale, and leg pain scale in lumbar spine surgery patients. Third, to compare the discriminative ability of two anchors: a global health assessment and a rating of satisfaction with the results of the surgery. STUDY DESIGN This study is a review of prospectively collected patient-reported outcomes data. PATIENT SAMPLE A total of 454 patients from a large database of surgeries performed by the Lumbar Spine Study Group with a 1-year follow-up on either ODI or PCS were included in the study. OUTCOME MEASURES Preoperative and 1-year postoperative scores for ODI, PCS, back pain scale, leg pain scale, health transition item (HTI) of the SF-36, and Satisfaction with Results scales. METHODS ODI, SF-36, and pain scales were administered before and 1 year after spinal surgery. Several candidate MCID calculation methods were applied to the data and the resulting values were compared. The HTI of the SF-36 was used as the anchor and compared with a second anchor (Satisfaction with Results scale). RESULTS Potential MCID calculations yielded a range of values: fivefold for ODI, PCS, and leg pain, 10-fold for back pain. Threshold values obtained with the two anchors were very similar. CONCLUSIONS The minimum detectable change (MDC) appears as a statistically and clinically appropriate MCID value. MCID values in this sample were 12.8 points for ODI, 4.9 points for PCS, 1.2 points for back pain, and 1.6 points for leg pain.

Perioperative Complications of Posterior Lumbar Decompression and Arthrodesis in Older Adults

BACKGROUND Lumbar arthrodesis is commonly done in elderly patients to treat degenerative spine problems. These patients may be at increased risk for complications because of their age and associated medical conditions. In this study, we examined the rates of perioperative complications associated with posterior lumbar decompression and arthrodesis in patients sixty-five years of age or older. METHODS We reviewed the hospital records of ninety-eight patients who were sixty-five years of age or older when they had a posterior decompression and lumbar arthrodesis with instrumentation, between 1993 and 1995, to treat degenerative disease of the spine. The average age was seventy-two years (range, sixty-five to eighty-four years). RESULTS Perioperative complications occurred in seventy-eight patients. Twenty-one patients had at least one major complication, and sixty-nine had at least one minor complication. Forty-nine patients had more than one complication. The most common major complication was wound infection (prevalence, 10%), and the most common minor complication was urinary tract infection (prevalence, 34%). The complication rate increased with older age, increased blood loss, longer operative time, and the number of levels of the arthrodesis. CONCLUSIONS Surgeons should be vigilant about perioperative complications in elderly patients treated with multi-level lumbar decompression and arthrodesis with instrumentation. Elderly patients should be made aware that they are at increased risk for surgical complications because of their age. Attention should be paid to controlling blood loss and limiting operative time.

Clinical Outcomes and Fusion Success at 2 Years of Single-level Instrumented Posterolateral Fusions With Recombinant Human Bone Morphogenetic Protein-2/compression Resistant Matrix versus Iliac Crest Bone Graft

Study Design. This is a prospective, randomized study comparing iliac crest bone graft to bone morphogenetic protein (BMP)/compression resistant matrix in instrumented posterolateral fusions for single-level lumbar degenerative disease. A higher recombinant human bone morphogenetic protein (rhBMP)-2 dose and a carrier specific for posterior spine applications were used. Objectives. As part of a Food and Drug Administration IDE study, clinical outcomes and fusion rates of single-level instrumented posterolateral fusions using iliac crest bone graft or BMP/compression resistant matrix were evaluated. Summary of Background Data. Although iliac crest graft is the gold standard for lumbar fusion, alternatives to obviate the morbidity of graft harvest have become available. Randomized clinical trials have demonstrated equivalent fusion rates and clinical outcomes with rhBMP-2 and a collagen sponge versus autograft in anterior lumbar fusions. A human pilot study using rhBMP-2 with biphasic calcium phosphate demonstrated similar results for posterolateral fusions. Methods. Demographic and perioperative data, Short Form 36, Oswestry Low Back Pain Disability Index, and leg and back pain scores were determined before surgery, and 1.5, 3, 6, 12, and 24 months after surgery. Independent neuroradiologists’ evaluation of fine-cut computerized tomography scans with reconstructions were obtained at 6, 12, and 24 months. Results. There were 98 subjects, 45 in the iliac crest bone graft group and 53 in the BMP/compression resistant matrix group. There were no significant differences for age, weight, sex, smoking, or previous surgery between the groups. The average operative time (2.9 hours) and blood loss (465 cc) in the iliac crest bone graft group was greater than in the BMP/compression resistant matrix group (2.4 hours and 273 cc). There were no significant differences in any outcome measure at all time intervals. The fusion rate was lower in the iliac crest bone graft group (73%) than in the BMP/compression resistant matrix group (88%) at P = 0.051. Conclusion. There was significant improvement of Short Form 36 (physical component score and pain), Oswestry Low Back Pain Disability Index, and leg and back pain scores in both groups over all time intervals. Surgical time and blood loss were significantly less in the BMP/compression resistant matrix group. The fusion rate in the BMP/compression resistant matrix group was significantly higher than the iliac crest bone graft group.

Off-Label Use of Bone Morphogenetic Proteins in the United States Using Administrative Data

Study Design. Epidemiological study using national administrative data. Objective. To evaluate the temporal trends in on-label and off-label bone morphogenetic protein (BMP) usage in primary and revision spine fusion by spine region and surgical approach, and nonspine applications in the United States from 2002 to 2007. Summary of Background Data. The prevalence of BMP usage for spine fusion has been on the rise, but its use has not been stratified by surgical approach, particularly for lumbar fusion where it has only been Food And Drug Administration-approved for anterior lumbar interbody fusion (ALIF). Methods. The prevalence of BMP usage in the United States was evaluated using the Nationwide Inpatient Sample between October 1, 2002 and December 31, 2007. The Nationwide Inpatient Sample is the single largest all-payer inpatient care database in the United States. The principal procedure associated with BMP use was determined, and the prevalence of BMP use was calculated for various population subgroups. Results. A total of 340,251 inpatient procedures with BMP usage were identified. Between 2003 and 2007, the annual number of procedures involving BMP increased by 4.3-fold from 23,900 to 103,194. Spine fusion accounted for the vast majority (92.8%) of principal procedures with BMP. The predominant use of BMP was in primary posterior lumbar interbody fusion or transforaminal lumbar interbody fusion (PLIF/TLIF) (30.0%), followed by primary posterolateral spine fusion (20.4%), primary ALIF (16.6%), primary cervical fusions (13.6%), and primary thoracolumbar fusions (3.9%). Of primary ALIF with BMP, 19.3% did not involve the implantation of an interbody device. Conclusion. At least 85% of principal procedures using BMP were for off-label applications. With uncertainty regarding the risks of using BMP in certain off-labelapplications, further research will be needed to better define the appropriate indications. Our study also demonstrates that disparities in the differential rates of BMP use exist in the spine fusion population.

Clinical and Radiographic Analysis of an Optimized rhBMP-2 Formulation as an Autograft Replacement in Posterolateral Lumbar Spine Arthrodesis

BACKGROUND Previous studies have demonstrated the ability of recombinant human bone morphogenetic protein to achieve a solid fusion in anterior lumbar interbody arthrodesis. The purpose of this study was to compare iliac crest bone graft and recombinant human bone morphogenetic protein-2, combined with a carrier consisting of bovine collagen and beta-tricalcium phosphate-hydroxyapatite to create a compression-resistant matrix, for instrumented single-level posterolateral arthrodesis. METHODS Four hundred and sixty-three patients with symptomatic single-level lumbosacral degenerative disease with no greater than grade-1 spondylolisthesis were treated with single-level instrumented posterolateral arthrodesis through an open midline approach. Patients were randomly assigned to either the recombinant human bone morphogenetic protein-2 matrix group (239 patients) or the autogenous iliac crest bone-graft group (224 patients). The Oswestry Disability Index, Short Form-36, and back and leg pain scores were determined preoperatively and at 1.5, three, six, twelve, and twenty-four months postoperatively. Radiographs and computed tomography scans were made at six, twelve, and twenty-four months postoperatively to evaluate for fusion. RESULTS The mean operative time and mean blood loss in the recombinant human bone morphogenetic protein-2 matrix group (2.5 hours and 343.1 mL, respectively) were significantly less than those in the iliac crest bone-graft group (2.9 hours and 448.6 mL). Both groups showed similar improvements in clinical outcomes and reduced pain. At twenty-four months, 60% of the iliac crest bone-graft group reported donor-site pain. At twenty-four months, fusion was evident in 96% of the patients in the recombinant human bone morphogenetic protein-2 matrix group compared with 89% in the iliac crest bone-graft group (p = 0.014). There was a significant difference (p = 0.011) in the rate of failures because of nonunion (eighteen patients with an iliac crest bone graft compared with six patients with the recombinant human bone morphogenetic protein-2 matrix). Also, the number of patients requiring second surgeries was significantly higher in the iliac crest bone-graft group (thirty-six patients) compared with the recombinant human bone morphogenetic protein-2 matrix group (twenty patients) (p = 0.015). CONCLUSIONS The use of recombinant human bone morphogenetic protein-2 in instrumented posterolateral lumbar arthrodesis decreases operative time and blood loss and produces earlier and higher fusion rates than does iliac crest bone graft. Clinical outcomes are similar to those with iliac crest bone graft. Thus, the need for harvesting iliac crest bone is eliminated along with the morbidities associated with the harvest procedure.

Treatment of Pyogenic Vertebral Osteomyelitis With Anterior Debridement and Fusion Followed by Delayed Posterior Spinal Fusion

Study Design. Case series. Objectives. The results of surgical treatment of osteomyelitis with anterior debridement and fusion followed by delayed posterior stabilization and fusion are presented. Methods. Forty-two patients with vertebral osteomyelitis are presented. There were 5 cervical, 12 thoracic, 1 thoracolumbar, 19 lumbar, and 5 lumbosacral lesions. The most frequently identified organism was Staphylococcus aureus. Most patients had significant comorbidities, including diabetes, or were immunocompromised. Ninety percent had elevated erythrocyte sedimentation rates and C-reactive proteins, while white blood cell counts were less reliably elevated. Imaging studies included radiographs, CT scans, and MRIs. All patients were treated with anterior debridement and strut grafting followed by 14.4 days of intravenous antibiotics and delayed instrumented posterior fusions and received 6 weeks of intravenous antibiotics after surgery. Results. All patients had resolution of their infections with no recurrence. There were two deaths. Neurologic deficits resolved in all patients. The diagnosis of pyogenic vertebral osteomyelitis is frequently delayed and presents a significant surgical challenge. The indications for surgical debridement were neurologic compromise, failed medical treatment, soft tissue extension, extensive vertebral body and disc space destruction, and progressive deformity. Many of these patients were severely ill at presentation and required urgent treatment. Anterior debridement and fusion followed by intravenous antibiotics allows for restoration of anterior column support and control of the infection before posterior instrumentation and fusion. Conclusion. This study demonstrates that anterior surgical debridement with fusion, followed by a period of intravenous antibiotics and delayed instrumented posterior fusion, is highly effective in the treatment of pyogenic osteomyelitis that has failed medical management.

Platelet Gel (agf) Fails to Increase Fusion Rates in Instrumented Posterolateral Fusions

Study Design. Retrospective cohort study. Objective. To determine the effect on fusion of adding platelet gel to autologous iliac crest graft. Summary of Background Data. Platelet gel is an osteoinductive material prepared by ultra-concentration of platelets and contains multiple growth factors. Proprietary commercial methods are available for harvesting autologous platelet gel concentrates for use as graft supplement in spine fusions. Methods. We reviewed 76 consecutive patients who underwent instrumented posterolateral lumbar fusion with autologous iliac crest bone graft mixed with autologous growth factor (AGF). A control group was randomly selected from patients who underwent instrumented posterolateral lumbar fusion with autologous bone graft alone. The groups were matched for age, sex, smoking history, and number of levels fused. Demographic, surgical, and clinical data were collected from medical records. Diagnosis of nonunion was based on exploration during revision surgery or evidence of nonunion on computerized tomography. The Fisher exact test was used to compare fusion rates. Results. In both groups, mean age was 50 years, and 24% were smokers. The nonunion rate was 25% in the AGF group and 17% in the control group. This difference was not statistically significant (P = 0.18). Conclusions. Platelet gel preparation requires blood draws from the patient. This procedure adds to the risk and cost of surgery. The technique for AGF harvest evaluated in this study provides the highest concentration of platelets among the commercially available methods. Despite this, we showed that platelet gel failed to enhance fusion rate when added to autograft in patients undergoing instrumented posterolateral spinal fusion. The authors do not recommend the use of platelet gel to supplement autologous bone graft during instrumented posterolateral spinal fusion.

Pediatric Spine Fractures: A Review of 137 Hospital Admissions

Objective: The anatomy and biomechanics of the growing spine produce failure patterns different from those in adults. Spinal injury in the pediatric patient is a concern as prevention of further neurologic damage and deformity and the good potential for recovery make timely identification and appropriate treatment of such injury critical. A retrospective clinical case series was conducted to present data from a large series of pediatric patients with spine injuries from a single regional trauma center. Methods: One hundred thirty-seven children with spine injuries were seen over 10 years and were divided into three age groups: 0-9, 10-14, and 15-17 years. Analysis of variance and χ2 were used to analyze differences between groups. Results: There were 36 patients aged 0-9, 49 aged 10-14, and 52 aged 15-17. Spine injury incidence increased with age. Motor vehicular accidents were the most common cause in this series. There were 36% cervical, 34% thoracic, 29% lumbar, 34% multilevel contiguous, and 7% multilevel noncontiguous involvement. Nineteen percent had spinal cord injury. Thirteen of 21 complete neurologic injuries and all 3 incomplete injuries improved. Cord injury was more common in the 0-9 age group. Four of five patients with spinal cord injury without radiographic abnormality (SCIWORA) were in the 0-9 age group and had complete neurologic injuries. Young children with cervical injuries were more likely to die than older children. Fifty-three percent had associated injuries. Eighteen percent underwent decompression, fusion, and instrumentation. Two patients developed scoliosis. The complication rate in surgical patients was higher than in patients treated nonsurgically and in polytrauma patients. This may be related to the severity of the initial injury. Our results suggest age-related patterns of injury that differ from previous work. The incidence of cord injury is 20% with higher frequencies in the young child. Potential for neurologic recovery is good. Young children have a higher risk for death than older children. There was no predominance of cervical injuries in the young child. The incidence of SCIWORA was low. Higher complication rates were seen in polytrauma and surgical patients.

Initial Fusion Rates With Recombinant Human Bone Morphogenetic Protein-2/compression Resistant Matrix and a Hydroxyapatite and Tricalcium Phosphate/collagen Carrier in Posterolateral Spinal Fusion

Study Design. Prospective, randomized, unblinded study of iliac crest bone graft (ICBG) versus recombinant human bone morphogenetic protein-2/compression resistant matrix (rhBMP-2/CRM)in a posterolateral instrumented fusion procedure. Objectives. Document initial radiographic characteristics, based on computed tomography, with rhBMP-2/CRM for posterolateral fusion at 6 and 12-month intervals. Summary of Background Data. As the acceptance of INFUSE bone graft as an ICBG replacement becomes more widespread, surgeons have begun to study applications for rhBMP-2 in posterior spinal fusion. Preclinical studies have examined variables including carrier composition, rhBMP-2 concentration, and rhBMP-2 dose. Pilot studies have been performed with encouraging initial results. Methods. Patients with single level lumbar degenerative disease were enrolled in a randomized study of ICBG versus rhBMP-2/CRM in a posterolateral instrumented fusion procedure. Computed tomography scans at 6 and 12 months were graded as demonstrating no fusion (grade 1), partial or limited unilateral fusion (grade 2), partial or limited bilateral fusion (grade 3), solid unilateral fusion (grade 4), or solid bilateral fusion (grade 5). Results. At our institution, 74 patients (38 rhBMP-2/CRM, 36 ICBG) reached minimum 1-year follow-up and were included in this analysis. Mean fusion grade (scale1–5) at 6 months after surgery was 4.35 in the rhBMP-2/CRM group versus 3.09 in the ICBG group (P < 0.0001). At 1 year after surgery mean fusion grade was 4.62 in the rhBMP-2/CRM group versus 3.77 in the ICBG group (P < 0.0023). Conclusions. These early results are encouraging and suggest a more rapid incorporation and development of the fusion mass with rhBMP-2/CRM than iliac crest autograft in a single level posterior instrumented fusion.

The Effect of Obesity on Clinical Outcomes After Lumbar Fusion

Study Design. Retrospective cohort analysis. Objective. To investigate and compare back and leg pain, and health-related quality of life measures in obese patients undergoing lumbar spine fusion, and to compare the results to nonobese patients. Summary of Background Data. Obesity is a growing healthcare crisis in the United States and an increasing number of patients undergoing spinal surgery are obese. Obesity is also associated with low back pain. Some obese patients with significant structural spine problems may be dismissed as having their pain only coming from their weight. We compared patient outcomes in obese and nonobese patients undergoing lumbar fusion surgery. Methods. We retrospectively reviewed a single-center patient database of patients undergoing lumbar fusion and identified 270 patients with greater than 2-year outcome data. Body mass index (BMI) was calculated and patients were classified as obese (BMI ≥ 30) or nonobese (BMI < 30). All patients completed Oswestry Disability Index (ODI), Short Form (SF)-36 questionnaires, and back and leg pain numerical rating scores before surgery and at 2 years. We compared clinical outcomes and complication rates in the 2 groups. Results. The overall study group consisted of 109 obese patients and 161 nonobese patients. Both the obese and nonobese patients demonstrated significant improvements in back pain, leg pain, SF-36 physical composite summary (PCS), and ODI scores (P < 0.001) at 2-year follow-up compared with baseline. There was no significant difference in the mean improvements seen in obese patients compared with nonobese patients with respect to back pain, leg pain, or SF-36 PCS or ODI scores. Both SF-36 PCS (P = 0.037) and ODI score (P = 0.028) at 2-year follow-up were better in the nonobese patients compared with the obese patients. Overall complication rates were slightly higher in the obese group (P = 0.045), predominantly because of wound-related complications. Conclusion. Obese patients undergoing lumbar fusion achieve similar benefits to nonobese patients. Wound-related complications are more common in obese patients. Obese patients with otherwise good indications for lumbar fusion should not be denied this procedure because of their weight.