Jeffrey A. Rihn

Complications associated with single-level transforaminal lumbar interbody fusion.

BACKGROUND CONTEXT The transforaminal lumbar interbody fusion (TLIF) procedure has become an increasingly popular means of obtaining a circumferential fusion while avoiding the morbidity of the anterior approach. Concerns remain, however, regarding the clinical efficacy and safety of its use. PURPOSE The purpose of this study was to evaluate the complications of the single-level TLIF procedure. The difference in complications observed with the use of iliac crest autograft compared with rhBMP-2 will be assessed. STUDY DESIGN Retrospective cohort study; a review of complications. METHODS Patients who underwent a single-level TLIF between January 2004 to May 2007 with either autograft iliac crest or rhBMP-2 were identified. A retrospective review of these patients included operative reports, pre- and postoperative medical records, most recent postoperative dynamic and static lumbar radiographs, and computed tomography scans (when available). RESULTS A total of 130 patients met the study criteria; 119 patients were available for follow-up, with an average radiographic follow-up of 19.1 months and an average clinical follow-up of 27.6 months. Thirty-three patients received iliac crest autograft and 86 patients received rhBMP-2. Complications occurred in 40 of the 119 study patients (33.6%). The autograft group had a higher complication rate (45.5% vs. 29.1%), but the difference was not statistically significant (p=.09). Complications in the autograft group included persistent donor-site pain (30.3%), donor-site infection (3.1%), lumbar wound infection (6.1%), and postoperative radiculitis (3.0%). Complications in the rhBMP-2 group included postoperative radiculitis (14.0%), vertebral osteolysis (5.8%), ectopic bone formation (2.3%), and lumbar wound infection (3.5%). A hydrogel sealant (Duraseal; Confluent Surgical Inc., Waltham, MA, USA) was used in 37 out of 86 patients in the rhBMP-2 group. The use of this sealant decreased the rate of postoperative radiculitis in the rhBMP-2 group from 20.4% to 5.4% (p=.047). The radiographic nonunion rate at most recent follow-up was 3.0% in the autograft group and 3.5% (p=.90) in the rhBMP-2 group. CONCLUSIONS The most common complications in the autograft group were related to the donor site. The most common complication in the rhBMP-2 group was postoperative radiculitis, the incidence of which is reduced by the use of a hydrogel sealant.

The Influence of Obesity on the Outcome of Treatment of Lumbar Disc Herniation: Analysis of the Spine Patient Outcomes Research Trial (SPORT)

BACKGROUND Questions remain as to the effect that obesity has on patients managed for symptomatic lumbar disc herniation. The purpose of this study was to determine if obesity affects outcomes following the treatment of symptomatic lumbar disc herniation. METHODS An as-treated analysis was performed on patients enrolled in the Spine Patient Outcomes Research Trial for the treatment of lumbar disc herniation. A comparison was made between patients with a body mass index of <30 kg/m² (nonobese) (n = 854) and those with a body mass index of ≥30 kg/m² (obese) (n = 336). Baseline patient demographic and clinical characteristics were documented. Primary and secondary outcomes were measured at baseline and at regular follow-up time intervals up to four years. The difference in improvement from baseline between operative and nonoperative treatment was determined at each follow-up period for both groups. RESULTS At the time of the four-year follow-up evaluation, improvements over baseline in primary outcome measures were significantly less for obese patients as compared with nonobese patients in both the operative treatment group (Short Form-36 physical function, 37.3 compared with 47.7 points [p < 0.001], Short Form-36 bodily pain, 44.2 compared with 50.0 points [p = 0.005], and Oswestry Disability Index, -33.7 compared with -40.1 points [p < 0.001]) and the nonoperative treatment group (Short Form-36 physical function, 23.1 compared with 32.0 points [p < 0.001] and Oswestry Disability Index, -21.4 compared with -26.1 points [p < 0.001]). The one exception was that the change from baseline in terms of the Short Form-36 bodily pain score was statistically similar for obese and nonobese patients in the nonoperative treatment group (30.9 compared with 33.4 points [p = 0.39]). At the time of the four-year follow-up evaluation, when compared with nonobese patients who had been managed operatively, obese patients who had been managed operatively had significantly less improvement in the Sciatica Bothersomeness Index and the Low Back Pain Bothersomeness Index, but had no significant difference in patient satisfaction or self-rated improvement. In the present study, 77.5% of obese patients and 86.9% of nonobese patients who had been managed operatively were working a full or part-time job. No significant differences were observed in the secondary outcome measures between obese and nonobese patients who had been managed nonoperatively. The benefit of surgery over nonoperative treatment was not affected by body mass index. CONCLUSIONS Obese patients realized less clinical benefit from both operative and nonoperative treatment of lumbar disc herniation. Surgery provided similar benefit over nonoperative treatment in obese and nonobese patients.

Infection after the surgical treatment of adolescent idiopathic scoliosis: evaluation of the diagnosis, treatment, and impact on clinical outcomes.

Study Design. Retrospective case-control. Objective. The purpose of this study was to evaluate a single surgeons experience with infection after surgical treatment of adolescent idiopathic scoliosis, with a focus on the diagnosis, treatment, and impact on radiographic and patient-reported outcomes. Summary of Background Data. Although previous studies have evaluated this postoperative complication, no studies to date have looked at the impact of this complication on both radiographic and patient-reported outcomes. Methods. From 1986 to 2004, 236 patients were identified who underwent surgical treatment of adolescent idiopathic scoliosis and had at least 2-year follow-up. The medical records of patients who developed infection were retrospectively reviewed in detail. Preoperative and most recent postoperative radiographic parameters and Scoliosis Research Society 24 outcomes of both infected and noninfected patients were compared. Results. Of 236 patients 7 (3%) developed an infection. One was acute (17 days postoperative), and 6 were delayed (average 34.2 months postoperative). The most common presenting complaints included back pain (5 of 7) and localized swelling (4 of 7). All patients with delayed infection were treated with 1 surgery (irrigation and debridement, instrumentation removal) and 6 weeks of intravenous antibiotics. Of 6 patients 3 had pseudarthrosis. Culture results were: Staphylococcus epidermidis (n = 2), Propionibacterium acnes (n = 1), Enteroccocus faecalis (n = 1), Group A Streptococcus (n = 1), no growth (n = 1). The patient with acute infection required 6 surgical procedures and 16 weeks of antibiotics. Cultures were positive for methicillin resistant Staphylococcus aureus and Serratia marscesens. Revision fusion surgery was performed 5 months after the infection was treated. Compared with the noninfected patients, those with infection had lower percent thoracic (P = 0.01) and lumbar (P = 0.06) curve correction. There was no difference in the pain, function, self-image, satisfaction, or total Scoliosis Research Society 24 scores. Conclusion. Postoperative infection after the surgical treatment of idiopathic scoliosis can successfully be treated with irrigation and debridement, instrumentation removal, and a course of antibiotics. Although less curve correction was achieved in the infected group, there were no differences in patient-reported outcomes when compared with the noninfected group.

Graft options in posterolateral and posterior interbody lumbar fusion.

Study Design. Review article, review of literature. Objective. To review the bone graft options that exist for posterolateral and posterior interbody lumbar fusion. Summary of Background Data. As the number of lumbar fusion surgeries has increased over the last decade, alternative methods of grafting have been developed. Iliac crest autograft bone has traditionally been used for lumbar fusion. The downside to this graft option, however, is donor site morbidity. Methods. The current literature on alternatives to iliac crest autograft bone for obtaining lumbar fusion was reviewed. Results. Platelet gels, demineralized bone matrix, synthetic bone graft, and bone morphogenetic protein are potential options for bone graft supplementation or substitution. In preclinical studies, platelet gels have been beneficial to bone growth when combined with autograft, but clinical studies do not support the use of platelet gel in posterolateral lumbar fusion. Preclinical studies of demineralized bone matrix have shown significant variability in the osteoinductive properties of the available products, and clinical data showing efficacy is limited. The use of synthetic bone graft material (ceramics) in lumbar fusion surgery is increasing. Calcium phosphate compounds (i.e., &bgr;-tricalcium phosphate and hydroxyapetite) are most commonly used and are often combined with type I collagen to form a matrix. These materials provide an osteoconductive scaffold for bony ingrowth and can be combined with bone marrow aspirate or used as a carrier for osteogenic factors. Bone morphogenetic protein (rhBMP-2) has been shown to provide similar or even increased fusion rates over autograft iliac crest bone. There are, however, potential safety concerns associated with the use of bone morphogenetic protein that are not fully understood. Conclusion. Several alternatives to iliac crest autograft bone provide promising early clinical results in achieving posterolateral and posterior interbody lumbar fusion.

Cervical spine injuries in American football.

American football is a high-energy contact sport that places players at risk for cervical spine injuries with potential neurological deficits. Advances in tackling and blocking techniques, rules of the game and medical care of the athlete have been made throughout the past few decades to minimize the risk of cervical injury and improve the management of injuries that do occur. Nonetheless, cervical spine injuries remain a serious concern in the game of American football. Injuries have a wide spectrum of severity. The relatively common ‘stinger’ is a neuropraxia of a cervical nerve root(s) or brachial plexus and represents a reversible peripheral nerve injury. Less common and more serious an injury, cervical cord neuropraxia is the clinical manifestation of neuropraxia of the cervical spinal cord due to hyperextension, hyperflexion or axial loading. Recent data on American football suggest that approximately 0.2 per 100 000 participants at the high school level and 2 per 100 000 participants at the collegiate level are diagnosed with cervical cord neuropraxia. Characterized by temporary pain, paraesthesias and/or motor weakness in more than one extremity, there is a rapid and complete resolution of symptoms and a normal physical examination within 10 minutes to 48 hours after the initial injury. Stenosis of the spinal canal, whether congenital or acquired, is thought to predispose the athlete to cervical cord neuropraxia. Although quite rare, catastrophic neurological injury is a devastating entity referring to permanent neurological injury or death. The mechanism is most often a forced hyperflexion injury, as occurs when ‘spear tackling’. The mean incidence of catastrophic neurological injury over the past 30 years has been approximately 0.5 per 100 000 participants at high school level and 1.5 per 100 000 at the collegiate level. This incidence has decreased significantly when compared with the incidence in the early 1970s. This decrease in the incidence of catastrophic injury is felt to be the result of changes in the rules in the mid- 1970s that prohibited the use of the head as the initial contact point when blocking and tackling. Evaluation of patients with suspected cervical spine injury includes a complete neurological examination while on the field or the sidelines. Immobilization on a hard board may also be necessary. The decision to obtain radiographs can be made on the basis of the history and physical examination. Treatment depends on severity of diagnosed injury and can range from an individualized cervical spine rehabilitation programme for a ‘stinger’ to cervical spine decompression and fusion for more serious bony or ligamentous injury. Still under constant debate is the decision to return to play for the athlete.

Injury of the posterior ligamentous complex of the thoracolumbar spine: a prospective evaluation of the diagnostic accuracy of magnetic resonance imaging.

Study Design. Prospective diagnostic imaging study. Objective. To determine the accuracy of magnetic resonance imaging (MRI) in diagnosing injury of the posterior ligamentous complex (PLC) in patients with thoracolumbar trauma. Summary of Background Data. Treatment decisions in thoracolumbar injury patients are currently based on the status of the PLC. It is, therefore, important to understand the accuracy of MRI in diagnosing varying degrees of PLC injury. Prior studies report that MRI is up to 100% sensitive for diagnosing PCL injury. Methods. Patients with an acute injury from T1 to L3 who required posterior surgery were prospectively studied. A musculoskeletal radiologist, based on the preoperative MRI findings, characterized each of the 6 components of the PLC as intact, incompletely disrupted, or disrupted. During the surgical procedure, the surgeon identified each component of the PLC as intact, incompletely disrupted, or disrupted. The radiologists interpretation and surgical findings were compared. Results. Forty-two patients with 62 levels of injury were studied. There were 33 males (78.6%) and 9 females (21.4%), and the average age was 35.7 years. According to the kappa score, there was a moderate level of agreement between the radiologists interpretation and the intraoperative findings for all PLC components except the thoracolumbar fascia, for which there was slight agreement. The sensitivity for the various PLC components ranged from 79% (left facet capsule) to 90% (interspinous ligament). The specificity ranged from 53% (thoracolumbar fascia) to 65% (ligamentum flavum). There was less agreement between the radiologist and surgeon for the patients with less severe neurologic compromise, i.e., those patients with an AIS grade of either D or E. Conclusion. The sensitivity and specificity of MRI for diagnosing injury of the PLC are lower than previously reported in the literature. The integrity of the PLC as determined by MRI should not be used in isolation to determine treatment.

Adjacent segment disease in the lumbar spine following different treatment interventions.

BACKGROUND CONTEXT Adjacent segment disease (ASD) is symptomatic deterioration of spinal levels adjacent to the site of a previous fusion. A critical issue related to ASD is whether deterioration of spinal segments adjacent to a fusion is due to the spinal intervention or due to the natural history of spinal degenerative disease. PURPOSE The purpose of this review is to summarize the recent clinical literature on adjacent segment disease in light of the natural history, patient-modifiable risk factors, surgical risk factors, sagittal balance, and new technology. STUDY DESIGN This review will evaluate the recent literature on genetic and hereditary components of spinal degenerative disease and potential links to the development of ASD. METHODS After a meticulous search of Medline for relevant articles pertaining to our review, we summarized the recent literature on the rate of ASD and the effect of various interventions, including motion preservation, sagittal imbalance, arthroplasty, and minimally invasive surgery. RESULTS The reported rate of ASD after decompression and stabilization procedures is approximately 2% to 3% per year. The factors that are consistently associated with adjacent segment disease include laminectomy adjacent to a fusion and a sagittal imbalance. CONCLUSIONS Spinal surgical interventions have been associated with ASD. However, whether such interventions may lead to an acceleration of the natural history of the disease remains questionable.

Does incorrect level needle localization during anterior cervical discectomy and fusion lead to accelerated disc degeneration

Study Design. Retrospective radiographic analysis. Objective. To retrospectively review a group of patients undergoing anterior cervical discectomy and fusion (ACDF) to determine the relative risk of adjacent level disc degeneration after incorrect needle localization. Summary of Background Data. The needle puncture technique is a well-established method to cause disc degeneration in experimental animal studies. The risk for accelerated degeneration because of needle puncture in humans is unknown. Methods. A retrospective radiographic analysis of 87 consecutive patients after single or 2-level ACDF with anterior plate instrumentation was performed. Perioperative and follow-up radiographs were used to grade disc degeneration according to a previously described scale. Results. Eighty-seven patients were included in the study (36 underwent 1-level ACDF, and 51 underwent 2-level ACDF). Seventy-two had correct needle localization at the level of planned surgery; 15 had incorrect needle localization (1 level above the operative level). There were no differences between the 2 groups in age, sex and length of follow-up. Patients in the incorrectly marked group were statistically more likely to demonstrate progressive disc degeneration with an odds ratio of 3.2. There was no correlation between age and length of follow-up with development of disc degeneration. Conclusion. There is a 3-fold increase in risk of developing adjacent level disc degeneration in incorrectly marked discs after ACDF at short-term follow-up. This may indicate that either needle related trauma or unnecessary surgical dissection contributes to accelerated adjacent segment degeneration.

Does Lumbar Facet Fluid Detected on Magnetic Resonance Imaging Correlate With Radiographic Instability in Patients With Degenerative Lumbar Disease

Study Design. Retrospective radiographic/imaging study. Objective. The purpose of this study was to analyze the association between lumbar facet fluid on MRI and sagittal instability on flexion lumbar radiographs in patients with degenerative disease at L4–L5. We hypothesized that the amount of facet fluid on MRI correlates with instability on the flexion radiograph. Summary of Background Data. Although never formally studied, it has been suggested that lumbar facet fluid detected on MRI is indicative of spinal segment instability. Methods. Patients who underwent laminectomy or laminectomy and fusion for the treatment of degenerative lumbar disease at L4–L5 at our institution between 2002 and 2004 and who had preoperative lumbar MRI and anteroposterior and flexion-extension radiographs available for review were study eligible. Axial T2 MRI images through the L4–L5 facets were analyzed for facet fluid. The facet fluid index was calculated, i.e., the ratio of the sum of the width of fluid in each facet (bilateral) to the sum of the width of each facet (bilateral). Instability on the flexion radiograph was measured as percent anterior slip at L4–L5. Results. Fifty-one patients were included in the study, 28 (55%) of whom had facet fluid noted on MRI. Of those patients who did have facet fluid on the MRI, 23 of 28 had instability on the flexion lumbar radiograph and 5 of 28 had no instability. The mean facet fluid index and percent anterior slip for the 28 patients with MRI facet fluid was 0.12% and 11.1%, respectively. There was a positive linear association between these values (Pearson correlation coefficient of 0.90, P < 0.001). The positive predictive value of L4–L5 facet fluid on MRI as an indicator of radiographic instability was 82%. Conclusions. There is a close linear association between the facet fluid index and the amount of radiographic instability at L4–L5. Facet fluid on MRI should raise high suspicion of lumbar instability.

Using magnetic resonance imaging to accurately assess injury to the posterior ligamentous complex of the spine: a prospective comparison of the surgeon and radiologist

OBJECT Magnetic resonance imaging has been proposed as a powerful technique for assessing the integrity of the posterior ligamentous complex (PLC) in spinal trauma. Because MR imaging is often used to determine appropriate treatment, it is important to determine the accuracy and reliability of MR imaging in diagnosing PLC disruption. The purpose of this study is to compare the ability of the radiologist and surgeon to assess disruption of the PLC in the setting of acute cervical and thoracolumbar trauma using MR imaging. METHODS The components of the PLC in 89 consecutive patients with cervical or thoracolumbar fractures following acute spinal trauma were evaluated using MR imaging by both a musculoskeletal radiologist and an independent spine surgeon and assessed intraoperatively under direct visualization by the treating surgeon. The MR imaging interpretations of the musculoskeletal radiologist and surgeon were compared with the intraoperative report for accuracy, sensitivity, specificity, and positive and negative predictive values. A comparison between the radiologists and spine surgeons accuracy of MR imaging interpretation was performed. RESULTS The agreement between both the spine surgeons and radiologists MR imaging interpretation and the actual intraoperative findings was moderate for most components of the PLC. Overall, the MR imaging interpretation of the surgeon was more accurate than that of the radiologist. The interpretation of MR imaging by the surgeon had negative predictive value and sensitivity of up to 100%. However, the specificity of MR imaging for both the surgeon and radiologist was lower, ranging from 51.5 to 80.5%. CONCLUSIONS Comparison of the MR imaging interpretations between surgeon and radiologist indicates that the surgeon was more accurate for some PLC components. The relatively low positive predictive value and specificity for MR imaging in assessing PLC integrity suggests that both the surgeon and radiologist tend to overdiagnose PLC injury using MR imaging. This can lead to unnecessary surgeries if only MR imaging is used for treatment decision making.