Nitin N. Bhatia

Adjacent segment degeneration in the lumbar spine.

BACKGROUND A primary concern after posterior lumbar spine arthrodesis is the potential for adjacent segment degeneration cephalad or caudad to the fusion segment. There is controversy regarding the subsequent degeneration of adjacent segments, and we are aware of no long-term studies that have analyzed both cephalad and caudad degeneration following posterior arthrodesis. A retrospective investigation was performed to determine the rates of degeneration and survival of the motion segments adjacent to the site of a posterior lumbar fusion. METHODS Two hundred and fifteen patients who had undergone posterior lumbar arthrodesis were included in this study. The study group included 126 female patients and eighty-nine male patients. The average duration of follow-up was 6.7 years. Radiographs were analyzed with regard to arthritic degeneration at the adjacent levels both preoperatively and at the time of the last follow-up visit. Disc spaces were graded on a 4-point arthritic degeneration scale. Correlation analysis was used to determine the contribution of independent variables to the rate of degeneration. Survivorship analysis was performed to describe the degeneration of the adjacent motion segments. RESULTS Fifty-nine (27.4%) of the 215 patients had evidence of degeneration at the adjacent levels and elected to have an additional decompression (fifteen patients) or arthrodesis (forty-four patients). Kaplan-Meier analysis predicted a disease-free survival rate of 83.5% (95% confidence interval, 77.5% to 89.5%) at five years and of 63.9% (95% confidence interval, 54.0% to 73.8%) at ten years after the index operation. Although there was a trend toward progression of the arthritic grade at the adjacent disc levels, there was no significant correlation, with the numbers available, between the preoperative arthritic grade and the need for additional surgery. CONCLUSIONS The rate of symptomatic degeneration at an adjacent segment warranting either decompression or arthrodesis was predicted to be 16.5% at five years and 36.1% at ten years. There appeared to be no correlation with the length of fusion or the preoperative arthritic degeneration of the adjacent segment.

Body mass index in patients with slipped capital femoral epiphysis

Abstract: Approximately 20% of children with idiopathic slipped capital femoral epiphysis (SCFE) have bilateral disease. Predicting which patients will develop problems with both hips remains difficult. This is the first study to evaluate the relationship between body mass index (BMI) and unilateral and bilateral SCFEs. Height and weight measurements of patients presenting with SCFE to our institution were obtained and used to calculate the BMI. Of the 54 patients enrolled in the study, 16 ultimately had bilateral disease. The mean BMI of patients with bilateral disease was significantly greater than that of patients with unilateral disease. In addition, patients presenting with unilateral involvement who progressed to bilateral disease had a significantly greater average BMI than patients who did not progress. Elevated BMI is associated with SCFE, especially bilateral SCFE.

Diagnostic modalities for the evaluation of pediatric back pain: a prospective study.

The commonly taught premise that pediatric back pain frequently has an underlying diagnosis has been recently challenged. Previous studies have suggested that up to 84% of children with low back pain have associated serious diagnoses. Children with back pain, therefore, have frequently undergone exhaustive diagnostic testing. There have been few prospective studies, however, about the diagnosis rate and appropriate diagnostic methods for back pain in children. This study prospectively examines the rate of diagnosis for pediatric back pain and the value of various diagnostic studies for this problem. Methods: All patients presenting to our institution with a chief complaint of back pain were evaluated for the study. Inclusion criteria consisted of age younger than 18 years, no previous back surgery, no previous diagnosis given, and duration of pain longer than 3 months. Seventy-three patients were enrolled in the study, and an algorithm was created for diagnostic evaluation. The algorithm incorporated commonly used diagnostic techniques including radiographs, magnetic resonance imaging, computed tomography, bone scan, and laboratory studies. The end point was considered to be either (1) a definitive diagnosis or (2) no diagnosis and no symptomatic or clinical changes during a 2-year period. Results: Fifty-seven patients (78.1%) ended with no diagnosis. Of the remaining 16, 9 were diagnosed with spondylolysis with or without spondylolisthesis. Three other patients had abnormal laboratory values but no definitive diagnosis. Other diagnoses included Scheuermann disease (n = 2), osteoid osteoma (n = 1), and a herniated disk (n = 1). Conclusions: This investigation is the largest prospective study of diagnostic modalities in pediatric back pain to date. Contrary to most of the previously published data, most of our patients ended the study with no definitive diagnosis. In addition, the most of the diagnoses were made at initial physical examination or via initial plain radiographs. No diagnoses were missed using our algorithm. These results suggest that pediatric back pain frequently does not carry a definitive diagnosis and that exhaustive diagnostic protocols may not be necessary for this problem. Level of Evidence: Prospective study; Level 2 clinical evidence.

The role of the sternocleidomastoid muscle flap for esophageal fistula repair in anterior cervical spine surgery.

Study Design. A retrospective study was undertaken which evaluated the medical records and imaging studies of a subset of patients managed by the spine service at Jackson Memorial Hospital who were diagnosed with an esophageal perforation in the setting of spinal surgery. Objective. To assess the safety and efficacy of a sternocleidomastoid muscle flap in the repair of esophageal perforation in the setting of anterior cervical spine surgery. Summary of Background Data. The management of an esophageal fistula in the setting of spine surgery is challenging and starts with a prompt and accurate diagnosis. In addition to broad spectrum intravenous antibiotics, several methods have been described to repair the fistula, which range from enteral tube feeding, direct repair, and/or repair with a local or free muscle flap. Methods. The review encompassed medical records, discharge summaries, operative reports, and imaging studies. Data were gathered with specific attention to demographics, primary pathology, mechanism of esophageal injury, method of spinal stabilization, method of esophageal repair, and time to initiation of oral intake. Follow-up interviews were conducted either in-person or by telephone. Results. Six patients were treated over the study period. There were 3 men and 3 women. The mean age was 52.8 years. Primary pathologies were penetrating trauma, blunt trauma (2 cases), degenerative disease (2 cases), and tumor. Mechanisms of esophageal injury were penetrating trauma, acute iatrogenic, chronic iatrogenic (3 cases), and intubation trauma. The time to diagnosis ranged from immediate to 10 months. The method of spinal stabilization was anterior autograft followed by posterior instrumentation in 4 of 6 patients. The method of esophageal repair was an inferiorly based sternocleidomastoid (SCM) flap in 4 cases, primary repair in 1 case, and esophageal diversion alone in 1 case. The time to oral intake averaged 59.2 days (range, 23–113 days) in those with a SCM flap versus 153.5 days (range, 119–188 days) in those treated without a flap. Conclusion. The use of an SCM flap for the repair of esophageal injury, in the setting of anterior cervical spine surgery, is a safe and effective tool. An SCM flap appeared to improve the time in initiating oral intake without any significant morbidity.

Advances in the management of spinal cord injury.

Historically, clinical outcomes following spinal cord injury have been dismal. Over the past 20 years, the survival rate and long-term outcome of patients with spinal cord injury have improved with advances in both medical and surgical treatment. However, the efficacy and timing of these adjuvant treatments remain controversial. There has been a tremendous increase in the number of basic science and clinical studies on spinal cord injury. Current areas of investigation include early acute management, including early surgical intervention, as well as new pharmacotherapy and cellular transplantation strategies. It is unlikely that a single approach can uniformly address all of the issues associated with spinal cord injury. Thus, a multidisciplinary approach will be needed.

Flavokawain B, a Kava Chalcone, Induces Apoptosis in Synovial Sarcoma Cell Lines

Synovial sarcomas (SS) are soft tissue sarcomas with poor prognosis, displaying a lack of response to conventional cytotoxic chemotherapy. Although SS cell lines have moderate chemosensitivity to isofamide and doxorubicin therapy, the clinical prognosis is still poor. In this article, we showed that flavokawain B (FKB), a novel chalcone from kava extract, potently inhibits the growth of SS cell lines SYO‐I and HS‐SY‐II through induction of apoptosis. Treatment with FKB increased caspase 8, 9, and 3/7 activity compared to vehicle‐treated controls, indicating that both extrinsic and intrinsic apoptotic pathways were activated. Furthermore, FKB treatment of both cell lines resulted in increased mRNA and protein expression of death receptor‐5 and the mitochondrial pro‐apoptotic proteins Bim and Puma, while down‐regulating the expression of an inhibitor of apoptosis, survivin in a dose‐dependent manner. Our results suggest the natural compound FKB has a pro‐apoptotic effect on SS cell lines. FKB may be a new chemotherapeutic strategy for patients with SS and deserves further investigation as a potential agent in the treatment of this malignancy.

Biomechanical Evaluation of Short-Segment Posterior Instrumentation With and Without Crosslinks in a Human Cadaveric Unstable Thoracolumbar Burst Fracture Model

Study Design. This study evaluates the biomechanical characteristics of spinal instrumentation constructs in a human unstable thoracolumbar burst fracture model simulated by corpectomy. Objective. To compare the biomechanical characteristics of short-segment posterior instrumentation, with and without crosslinks, in a human unstable burst fracture model simulated by corpectomy. Summary of Background Data. Unstable thoracolumbar burst fractures are serious injuries, and their management remains controversial. Some authors advocate the use of short-segment posterior instrumentation for certain burst fractures. Whether crosslinks contribute additional stability has not been determined. Methods. Six fresh frozen human spines (T10–L2) were potted to isolate the T11–L1 segments, and biomechanically tested in axial rotation, lateral bending, flexion, and extension. A custom spine testing system was used that allows motion with 6 degrees of freedom. After testing was completed on intact specimens, a corpectomy was performed at T12 to simulate an unstable burst fracture with loss of anterior and middle column support. Short-segment transpedicular instrumentation was then performed from T11 to L1. Each specimen was retested with 1, 2, or no crosslinks. Construct stiffness and motion data were analyzed with each intact specimen serving as its own internal control. Results. Torsional stiffness in axial rotation was significantly increased (P < 0.05) in short-segment fixation constructs with 1 and 2 crosslinks, but none was restored to the preinjury baseline level. Significant reductions in standardized motion were also achieved with 1 and 2 crosslinks compared to no crosslinks (P < 0.05), but they remained greater than baseline. Crosslinks significantly increased stiffness and decreased motion in lateral bending, beyond the baseline level (P < 0.05). In flexion, all constructs had significantly decreased stiffness and increased motion compared to the intact specimen (P < 0.05), with crosslinks providing no additional benefit. Conversely, none of the constructs demonstrated a significant change in extension compared to baseline (P > 0.05). When attempting to load the constructs to failure, screw pullout was seen in all specimens. Conclusion. Crosslinks, when added to short-segment posterior fixation, improve stiffness and decrease motion in axial rotation, but do not restore baseline stability in this corpectomy model. Short-segment posterior fixation is also inadequate in restoring stability in flexion with injuries of this severity. Short-segment posterior instrumentation alone can achieve baseline stability in lateral bending, and crosslinks provide even greater stiffness.

Analysis of Prognostic Factors for Patients with Chordoma with Use of the California Cancer Registry

BACKGROUND Chordoma is the most common primary malignant tumor of the spine. It is extremely rare and has been studied primarily in single-institution case series. Using data from a large, population-based cancer registry, we designed the present study to examine the outcome for patients with chordoma and to determine relevant prognostic factors. METHODS A retrospective analysis of the California Cancer Registry database was performed to identify patients with a diagnosis of chordoma in the years 1989 to 2007. Comparisons examined differences in demographics, disease characteristics, treatment, and survival. Survival analyses were performed with use of the Kaplan-Meier method with log-rank tests and Cox proportional hazards models. RESULTS Four hundred and nine patients with chordoma were identified; 257 (62.8%) were male and 152 (37.2%) were female. With regard to racial or ethnic distribution, 266 patients (65%) were white; ninety-three (22.7%), Hispanic; forty-three (10.5%), Asian or other; and seven (1.7%), black. The site of presentation was the head in 202 patients (49.4%), spine in 106 patients (25.9%), and pelvis and/or sacrum in 101 patients (24.7%). Hispanic race (p = 0.0002), younger age (less than forty years; p < 0.0001), and female sex (p = 0.009) were associated with cranial presentation, whereas older age (forty years or older; p < 0.0001) was associated with pelvic presentation. After adjustment for clinically relevant factors, a significantly decreased risk of death for chordoma-specific survival was seen for Hispanic race (hazard ratio = 0.51, 95% confidence interval [95% CI], 0.28 to 0.93; p = 0.03), high socioeconomic status (hazard ratio = 0.8, 95% CI, 0.67 to 0.95; p = 0.01), and local excision and/or debulking (hazard ratio = 0.38, 95% CI, 0.18 to 0.81; p = 0.01). Large tumor size was independently associated with an increased risk of death (hazard ratio = 2.05, 95% CI, 1.01 to 4.20; p = 0.048). CONCLUSIONS In this study, the survival of patients with chordoma was significantly better for those who were Hispanic and had a small tumor, high socioeconomic status, and surgical intervention.

Role of Early Surgical Decompression of the Intradural Space After Cervical Spinal Cord Injury in an Animal Model

BACKGROUND The role of decompressing the intradural space through a durotomy as a treatment option for acute traumatic cervical spinal cord injury has not been explored in an animal model, to our knowledge. We sought to determine the role of durotomy and duraplasty in the treatment of acute cervical spinal cord injury and its effects on inflammation, scar formation, and functional recovery. METHODS Seventy-two adult female Sprague-Dawley rats were assigned to three groups: contusion injury alone, contusion injury with a decompressive durotomy, and contusion injury with a decompressive durotomy followed by placement of a dural allograft. A mild (200-kdyn [2-N]) contusive injury was delivered to the exposed spinal cord at C5. The injured segment was reexposed four hours after injury, and a durotomy with decompression was performed. When a dural allograft was used it was affixed to the surrounding intact dura with use of a fibrin sealant. The Grip Strength Meter was used to assess forelimb function. Animals were killed at two and four weeks, and immunohistochemical analysis was performed to assess scar formation, inflammatory cell infiltration, and lesional volume. RESULTS Immunohistochemical analysis revealed increased scar formation, cavitation, and inflammatory response in the animals treated only with a decompressive durotomy. Relative to the group with a contusion injury alone, the animals treated with a durotomy followed by a dural allograft had decreased cavitation and scar formation. Lesional volume measurements showed a significantly increased cavitation size at four weeks in both the contusion-only (mean and standard deviation, 12.6 +/- 0.5 mm(3)) and durotomy-only (15.1 +/- 1 mm(3)) groups relative to the animals that had received a dural allograft following durotomy (6.8 +/- 1.4 mm(3)). CONCLUSIONS Functional recovery after acute cervical spinal cord injury was better in animals treated with decompression of the intradural space and placement of a dural allograft than it was in animals treated with decompression alone. These functional data correlated directly with histological evidence of a decrease in spinal cord cavitation, inflammation, and scar formation.

Transplantation of preconditioned Schwann cells following hemisection spinal cord injury.

Study Design. Chronically compressed sciatic nerve segments were transplanted to hemisected spinal cord injured rats. Histologic evaluation and behavior functional outcomes were tested after 6 weeks following surgery. Objective. To evaluate the outcome of preconditioned peripheral nerves as a permissive environment in axonal regeneration of the injured spinal cord. Summary of Background Data. Schwann cells have been used to facilitate a permissive environment for the injured spinal cord to regenerate. Previous experiments have shown compressive mechanical stress to be important in stimulating the regenerative behavior of Schwann cells. Transplantation of highly permissive Schwann cell-enriched peripheral nerve grafts may enhance regeneration in spinal cord injury. Methods. Adult Sprague-Dawley rats (n = 24) were used to create a hemisection injury of the spinal cord. At 1-week postinjury creation, the spinal cords were reexposed for all animals. Peripheral nerve grafts were obtained from rat sciatic nerve, either untreated or subjected to mechanical compression for 2 weeks with nonconstrictive tubing. Transplantation of grafts was performed after a resection of the glial scar. Functional outcome was measured using the Basso, Beattie, Bresnahan Locomotor Rating Score and footprint analysis. Tract tracing of descending and ascending spinal cord tracts was performed at 6 weeks after surgery for histologic evaluation of axonal regeneration. Results. Preconditioned transplants had significantly higher Basso, Beattie, Bresnahan Scores versus hemisection alone in the late postoperative period (P < 0.05). They also had significantly less foot exorotation and base of support when compared to nonconditioned transplants. Histologic analysis showed increased regeneration at lesional sites for preconditioned transplants versus control group (P < 0.05). Conclusions. Functional recovery after hemisection injury improved significantly in the late postoperative period with transplantation of preconditioned peripheral nerve. Preconditioned grafts also exhibit sustained axonal regeneration at and past the lesional site in histologic analysis. Further investigation with later time points is warranted.