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Biomedical subjects

Sohail K Mirza

Publications and source records attributed to Sohail K Mirza.

At least 19 recordsLinked to original sources
PubMed2006

Lumbar fusion outcomes in Washington State workers' compensation.

STUDY DESIGN: Retrospective population-based cohort study. OBJECTIVE: To evaluate the influence of lumbar intervertebral fusion devices on clinical and disability outcomes among Washington State compensated workers with chronic back pain. SUMMARY OF BACKGROUND DATA: The efficacy of lumbar fusion for chronic low back pain remains controversial. Recent randomized controlled trials have shown results of fusion to be equivalent to those of structured exercise and cognitive intervention. Lumbar fusion rates, however, continue to increase nationally, fueled, in part, by introduction of new fusion devices, including intervertebral cages in 1996. It is not known whether these newer devices have improved outcomes, and particularly in compensated workers. METHODS: In this population-based retrospective cohort study, we identified Washington State injured workers who underwent lumbar fusion between 1994 and 2001 from Washington State Workers' Compensation system administrative database. All the data for this study were obtained from either the claims or medical bill payment databases. Multiple logistic regression analyses were used to examine the association between the surgical technique (interbody cages and/or instrumentation) and the risk of disability, reoperation, and complications following lumbar fusion. RESULTS: Among the 1,950 eligible subjects, fusions with cages increased from 3.6% in 1996 to 58.1% in 2001. Overall disability rate at 2 years after fusion was 63.9%, reoperation rate 22.1%, and rate for other complications 11.8%. Use of cages or instrumentation was associated with increased complication risk compared with bone-only fusions without improving disability or reoperation rates. Legal, work-related, and psychologic factors predicted worse disability. Discography and multilevel fusions predicted greater reoperation risk. Degenerative disc disease and concurrent decompression procedures predicted lower reoperation risk. CONCLUSIONS: Use of intervertebral fusion devices rose rapidly after their introduction in 1996. This increased use was associated with an increased complication risk without improving disability or reoperation rates.

Cohort Studies↗
PubMed2006

Back pain prevalence and visit rates: estimates from U.S. national surveys, 2002.

STUDY DESIGN: Review and analysis of data from two U.S. national surveys in 2002. OBJECTIVES: To examine the prevalence of back pain and physician visits for back pain in the United States. SUMMARY OF BACKGROUND DATA: National data on the prevalence of back pain become available only intermittently. METHODS: We summarized published data from the 2002 National Health Interview Survey (NHIS) on the prevalence of back pain and compared it with earlier surveys. We also analyzed the 2002 National Ambulatory Medical Care Survey (NAMCS) to determine physician visit rates for back pain. RESULTS: In the 2002 NHIS, there were 31,044 adult respondents. Low back pain lasting at least a whole day in the past 3 months was reported by 26.4% of respondents, and neck pain was reported by 13.8%. Among racial groups, American Indians and Alaska Natives had the highest prevalence of low back pain, and Asian Americans had the lowest. Prevalence generally declined with greater levels of education and increasing income. Prevalence estimates were consistent with those from previous surveys, although methodologic differences limited comparisons. NAMCS data suggested that the proportion of all physician visits attributable to low back pain (2.3% in 2002) has changed little since the early 1990s. CONCLUSIONS: About one fourth of U.S. adults report low back pain in the past 3 months; the proportion of physician visits attributed to back pain has changed little in the past decade.

Adult↗
PubMed2006

Population-based trends in volumes and rates of ambulatory lumbar spine surgery.

STUDY DESIGN: Sequential cross-sectional study. OBJECTIVES: To quantify patterns of outpatient lumbar spine surgery. SUMMARY OF BACKGROUND DATA: Outpatient lumbar spine surgery patterns are undocumented. METHODS: We used CPT-4 and ICD-9-CM diagnosis/procedure codes to identify lumbar spine operations in 20+ year olds. We combined sample volume estimates from the National Hospital Discharge Survey (NHDS), the National Survey of Ambulatory Surgery (NSAS), and the Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS) with complete case counts from HCUP's State Inpatient Databases (SIDs) and State Ambulatory Surgery Databases (SASDs) for four geographically diverse states. We excluded pregnant patients and those with vertebral fractures, cancer, trauma, or infection. We calculated age- and sex-adjusted rates. RESULTS: Ambulatory cases comprised 4% to 13% of procedures performed from 1994 to 1996 (NHDS/NSAS data), versus 9% to 17% for 1997 to 2000 (SID/SASD data). Discectomies comprised 70% to 90% of outpatient cases. Conversely, proportions of discectomies performed on outpatients rose from 4% in 1994 to 26% in 2000. Outpatient fusions and laminectomies were uncommon. NIS data indicate that nationwide inpatient surgery rates were stable (159 cases/100,000 in 1994 vs. 162/100,000 in 2000). However, combined data from all sources suggest that inpatient and outpatient rates rose from 164 cases/100,000 in 1994 to 201/100,000 in 2000. CONCLUSIONS: While inpatient lumbar surgery rates remained relatively stable for 1994 to 2000, outpatient surgery increased over time.

Adult↗
PubMed2006

Towards standardized measurement of adverse events in spine surgery: conceptual model and pilot evaluation.

BACKGROUND: Independent of efficacy, information on safety of surgical procedures is essential for informed choices. We seek to develop standardized methodology for describing the safety of spinal operations and apply these methods to study lumbar surgery. We present a conceptual model for evaluating the safety of spine surgery and describe development of tools to measure principal components of this model: (1) specifying outcome by explicit criteria for adverse event definition, mode of ascertainment, cause, severity, or preventability, and (2) quantitatively measuring predictors such as patient factors, comorbidity, severity of degenerative spine disease, and invasiveness of spine surgery. METHODS: We created operational definitions for 176 adverse occurrences and established multiple mechanisms for reporting them. We developed new methods to quantify the severity of adverse occurrences, degeneration of lumbar spine, and invasiveness of spinal procedures. Using kappa statistics and intra-class correlation coefficients, we assessed agreement for the following: four reviewers independently coding etiology, preventability, and severity for 141 adverse occurrences, two observers coding lumbar spine degenerative changes in 10 selected cases, and two researchers coding invasiveness of surgery for 50 initial cases. RESULTS: During the first six months of prospective surveillance, rigorous daily medical record reviews identified 92.6% of the adverse occurrences we recorded, and voluntary reports by providers identified 38.5% (surgeons reported 18.3%, inpatient rounding team reported 23.1%, and conferences discussed 6.1%). Trained observers had fair agreement in classifying etiology of 141 adverse occurrences into 18 categories (kappa = 0.35), but agreement was substantial (kappa > or = 0.61) for 4 specific categories: technical error, failure in communication, systems failure, and no error. Preventability assessment had moderate agreement (mean weighted kappa = 0.44). Adverse occurrence severity rating had fair agreement (mean weighted kappa = 0.33) when using a scale based on the JCAHO Sentinel Event Policy, but agreement was substantial for severity ratings on a new 11-point numerical severity scale (ICC = 0.74). There was excellent inter-rater agreement for a lumbar degenerative disease severity score (ICC = 0.98) and an index of surgery invasiveness (ICC = 0.99). CONCLUSION: Composite measures of disease severity and surgery invasiveness may allow development of risk-adjusted predictive models for adverse events in spine surgery. Standard measures of adverse events and risk adjustment may also facilitate post-marketing surveillance of spinal devices, effectiveness research, and quality improvement.

Humans↗
PubMed2006

Trends and variations in the use of spine surgery.

Examining trends and geographic variations in clinical care offers insights into changes in clinical decision making. We summarized data on spine surgical rates, trends, and variations in the United States to highlight areas of professional uncertainty and questions for future research. The United States has the highest rate of spine surgery in the world, but spine surgery shows wider geographic variations than most other procedures. For example, Medicare data for 2001 showed sixfold variations in spine surgery rates among United States cities, and 10-fold variations in spine fusion rates. United States spine surgery rates rose 55% in the 1980s. In the 1990s, studies of surgical rates became more difficult because 20% of discectomies shifted to an out-patient setting. Extrapolations from states with ambulatory surgery data suggest overall lumbar surgery rates continued to rise throughout the 1990s. The most rapid increase was for spinal fusion, which tripled during the 1990s and accounted for an increasing proportion of all spine procedures. Some increases coincided with the introduction of new surgical implants. Despite new technologies, rates of repeat surgery after fusion were no lower than the rates after decompression alone. As new technology for spine surgery is introduced at an accelerating pace, we anticipate substantial changes in surgery patterns. Analysis of population-based data may be useful for surveillance of changes and their impacts.

Humans↗
PubMed2006

The safety of fluoroscopically-assisted thoracic pedicle screw instrumentation for spine trauma.

BACKGROUND: Pedicle screw fixation is considered biomechanically superior to other stabilization constructs. However, the potential for severe complications have discouraged its use in the thoracic spine. Our goal is to determine the incidence of major perioperative complications following the placement of thoracic pedicle screws using anatomic landmarks and intraoperative fluoroscopy in patients with spine fractures. METHODS: Retrospective review of 245 consecutive patients with spine fractures requiring pedicle screw fixation between T1 and T10 at a regional Level I trauma center between 1995 and 2001. Database and medical record review were used to identify the incidence of major perioperative complications. A major complication was defined as a potentially life-threatening vascular injury, neurologic deterioration, pneumothorax or hemothorax, and tracheoesophageal injury. Patients were monitored for these complications from the time of surgery until discharge. RESULTS: In all, 1,533 pedicle screws were placed between T1 and T10 in 245 patients. No patient sustained a major complication related to screw placement. Three patients (1.2%) required a secondary procedure for prophylactic revision of four (0.26%) malpositioned screws. CONCLUSIONS: This study supports the safety of pedicle screws in the thoracic spine using preoperative imaging evaluation, standard posterior element landmarks and intraoperative fluoroscopy.

Bone Screws↗
PubMed2006

Recombinant human BMP-2 and allograft compared with autogenous bone graft for reconstruction of diaphyseal tibial fractures with cortical defects. A randomized, controlled trial.

BACKGROUND: Currently, the treatment of diaphyseal tibial fractures associated with substantial bone loss often involves autogenous bone-grafting as part of a staged reconstruction. Although this technique results in high healing rates, the donor-site morbidity and potentially limited supply of suitable autogenous bone in some patients are commonly recognized drawbacks. The purpose of the present study was to investigate the benefit and safety of the osteoinductive protein recombinant human bone morphogenetic protein-2 (rhBMP-2) when implanted on an absorbable collagen sponge in combination with freeze-dried cancellous allograft. METHODS: Adult patients with a tibial diaphyseal fracture and a residual cortical defect were randomly assigned to receive either autogenous bone graft or allograft (cancellous bone chips) for staged reconstruction of the tibial defect. Patients in the allograft group also received an onlay application of rhBMP-2 on an absorbable collagen sponge. The clinical evaluation of fracture-healing included an assessment of pain with full weight-bearing and fracture-site tenderness. The Short Musculoskeletal Function Assessment (SMFA) was administered before and after treatment. Radiographs were used to document union, the presence of extracortical bridging callus, and incorporation of the bone-graft material. RESULTS: Fifteen patients were enrolled in each group. The mean length of the defect was 4 cm (range, 1 to 7 cm). Ten patients in the autograft group and thirteen patients in the rhBMP-2/allograft group had healing without further intervention. The mean estimated blood loss was significantly less in the rhBMP-2/allograft group. Improvement in the SMFA scores was comparable between the groups. No patient in the rhBMP-2/allograft group had development of antibodies to BMP-2; one patient had development of transient antibodies to bovine type-I collagen. CONCLUSIONS: The present study suggests that rhBMP-2/allograft is safe and as effective as traditional autogenous bone-grafting for the treatment of tibial fractures associated with extensive traumatic diaphyseal bone loss. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.

Adult↗
PubMed2006

Risk factors for respiratory failure following operative stabilization of thoracic and lumbar spine fractures.

BACKGROUND: Respiratory failure is a serious complication that can adversely affect the hospital course and survival of multiply injured patients. Some studies have suggested that delayed surgical stabilization of spine fractures may increase the incidence of respiratory complications. However, the authors of these studies analyzed small sets of patients and did not assess the independent effects of multiple risk factors. METHODS: A retrospective cohort study was conducted at a regional level-I trauma center to identify risk factors for respiratory failure in patients with surgically treated thoracic and lumbar spine fractures. Demographic, diagnostic, and procedural variables were identified. The incidence of respiratory failure was determined in an adult respiratory distress syndrome registry maintained concurrently at the same institution. Univariate and multivariate analyses were used to determine independent risk factors for respiratory failure. An algorithm was formulated to predict respiratory failure. RESULTS: Respiratory failure developed in 140 of the 1032 patients in the study cohort. Patients with respiratory failure were older; had a higher mean Injury Severity Score (ISS) and Charlson Comorbidity Index Score; had greater incidences of pneumothorax, pulmonary contusion, and thoracic level injury; had a lower mean Glasgow Coma Score (GCS); were more likely to have had a posterior surgical approach; and had a longer mean time from admission to surgical stabilization than the patients without respiratory failure (p < 0.05). Multivariate analysis identified five independent risk factors for respiratory failure: an age of more than thirty-five years, an ISS of > 25 points, a GCS of < or = 12 points, blunt chest injury, and surgical stabilization performed more than two days after admission. An algorithm was created to determine, on the basis of the number of preoperative predictors present, the relative risk of respiratory failure when surgery was delayed for more than two days. CONCLUSIONS: Independent risk factors for respiratory failure were identified in an analysis of a large cohort of patients who had undergone operative stabilization of thoracic and lumbar spine fractures. Early operative stabilization of these fractures, the only risk factor that can be controlled by the physician, may decrease the risk of respiratory failure in multiply injured patients.

Adult↗
PubMed2006

Diagnosis and treatment of craniocervical dislocation in a series of 17 consecutive survivors during an 8-year period.

OBJECT: Craniocervical dissociation (CCD) is a highly unstable and usually fatal injury resulting from osseoligamentous disruption between the occiput and C-2. The purpose of this study was to elucidate systematic factors associated with delays in diagnosing and treating this life-threatening condition and to introduce an injury-severity classification with therapeutic implications. METHODS: In a retrospective evaluation of institutional databases, the authors reviewed medical records and original images obtained in 17 consecutive surviving patients with CCD treated between 1994 and 2002. Images and clinical results of treatment were evaluated, emphasizing the timing of diagnosis, clinical effect of delayed diagnosis, potential clinical or imaging warning signs, and response to treatment. Craniocervical dissociation was identified or suspected on the initial lateral cervical spine radiograph acquired in two patients (12%) and was diagnosed based on screening computerized tomography findings in two additional patients (12%). A retrospective review of initial lateral x-ray films showed an abnormal dens-basion interval in 16 patients (94%). The 2-day average delay in diagnosis was associated with profound neurological deterioration in five patients (29%). Neurological status declined in one patient after a fixation procedure was performed. There were no cases of craniocervical pseudarthrosis or hardware failure during a mean 26-month follow-up period. The mean American Spinal Injury Association (ASIA) motor score of 50 improved to 79, and the number of patients with useful motor function (ASIA Grade D or E) increased from seven (41%) preoperatively to 13 (76%) postoperatively. CONCLUSIONS: The diagnosis of CCD was frequently delayed, and the delay was associated with an increased likelihood of neurological deterioration. Early diagnosis and spinal stabilization protected against worsening spinal cord injury.

Adolescent↗
PubMed2005

A prospective cohort study of surgical treatment for back pain with degenerated discs; study protocol.

BACKGROUND: The diagnosis of discogenic back pain often leads to spinal fusion surgery and may partly explain the recent rapid increase in lumbar fusion operations in the United States. Little is known about how patients undergoing lumbar fusion compare in preoperative physical and psychological function to patients who have degenerative discs, but receive only non-surgical care. METHODS: Our group is implementing a multi-center prospective cohort study to compare patients with presumed discogenic pain who undergo lumbar fusion with those who have non-surgical care. We identify patients with predominant low back pain lasting at least six months, one or two-level disc degeneration confirmed by imaging, and a normal neurological exam. Patients are classified as surgical or non-surgical based on the treatment they receive during the six months following study enrollment. RESULTS: Three hundred patients discogenic low back pain will be followed in a prospective cohort study for two years. The primary outcome measure is the Modified Roland-Morris Disability Questionnaire at 24-months. We also evaluate several other dimensions of outcome, including pain, functional status, psychological distress, general well-being, and role disability. CONCLUSION: The primary aim of this prospective cohort study is to better define the outcomes of lumbar fusion for discogenic back pain as it is practiced in the United States. We additionally aim to identify characteristics that result in better patient selection for surgery. Potential predictors include demographics, work and disability compensation status, initial symptom severity and duration, imaging results, functional status, and psychological distress.

Back Pain↗
PubMed2004

The misdiagnosis of acute cervical spine injuries and fractures in infants and children: the 12-year experience of a level I pediatric and adult trauma center.

OBJECTIVE: The objective was to determine the frequency of acute cervical spine injuries and fractures that were misdiagnosed in infants and children (< or =14 years) initially evaluated at a pediatric and adult urban level I trauma center. METHODS AND RESULTS: This was a retrospective, single-institution, case series of pediatric cervical spine injuries and fractures that were misdiagnosed during initial emergency room imaging evaluation. "Misdiagnosed" cases were those cases whose imaging studies initially obtained in the emergency room were misinterpreted based on reevaluation by a senior trauma radiologist blinded to the initial results. Nineteen percent (7 out of 37) were misdiagnosed on initial emergency room imaging evaluation. Five percent were true "missed" fractures, and 14% were "normal and/or developmental variants" read as fractures or dislocation. CONCLUSIONS: The error rate for infants and children < or =8 years was 24%, and for children > or =9 years was 15%. The occiput to C2 region was the most common site of diagnostic error. The most common factors predisposing to misdiagnosis were unfamiliarity with pediatric cervical spine anatomy, failure to recognize normal variants seen during growth and development, and suboptimal conventional film techniques.

Adolescent↗
PubMed2004

Neural space integrity of the lower cervical spine: effect of anterior lesions.

STUDY DESIGN: A repeated measures study design was used to evaluate intervertebral foramen and spinal canal neural space integrity subsequent to sequential surgical anterior lesions of the lower cervical spine in a human cadaver model. OBJECTIVE: To investigate the degree to which sequential ablation of anterior vertebral elements places the neural structures at risk of injury. SUMMARY OF BACKGROUND DATA: Classic instability management utilizing functional-structural criteria has been widely examined associating specific lesions or pathologies to a degree of mechanical instability. Unfortunately, these studies have not assessed the neuroprotective role of the vertebral column. METHODS: Eight human cadaveric lower cervical spines were instrumented with transducers to measure geometrical changes in the intervertebral foramen and spinal canal. Sequential lesions were performed anteriorly on the anterior and middle column structures (C4-C5 disc and C5 vertebra), and their effects on neural space integrity and range of motion were measured under physiologic loading. RESULTS: Range of motion significantly increased with successively more destructive lesions, whereas the spinal canal exhibited few changes. Intervertebral foramen integrity was statistically reduced for corpectomy (66% intact), hemivertebrectomy (62% intact) and full vertebrectomy (57% intact) lesions when loaded in concomitant extension and ipsilateral bending (4 Nm). CONCLUSIONS: Lesions more extensive than a surgical discectomy have significant effects on the cervical neural foramens specifically when the spine is placed in extension, ipsilateral bending, and coupled ipsilateral bending and extension. Our study establishes a quantitative relationship between the risk of neural structure compression and anterior lesions of the spinal column under physiologic loading.

Aged↗
PubMed2004

Severe posttraumatic craniocervical instability in the very young patient. Report of three cases.

Children younger than 3 years of age represent a distinct subpopulation of patients at particular risk for high cervical and craniovertebral injuries. There are few descriptions of survivors of severe craniocervical trauma among the very young, and scarce data exist regarding management after initial emergency stabilization. The authors describe three children, age 1 to 32 months, who presented with craniocervical junction injuries. Variable neurological findings were observed at presentation (cranial nerve deficits, obtundation, and moderate-to-severe quadriparesis). All three were treated with prolonged immobilization and have recovered with minimal to no neurological deficit.

Child, Preschool↗
PubMed2003

Accuracy of thoracic vertebral body screw placement using standard fluoroscopy, fluoroscopic image guidance, and computed tomographic image guidance: a cadaver study.

STUDY DESIGN: A surgical simulation study in human cadaver spine specimens was conducted to evaluate the accuracy of thoracic vertebral body screw placement using four different intraoperative imaging techniques. OBJECTIVE: To compare standard fluoroscopy, fluoroscopy-based image guidance with two different referencing methods, and computed tomography-based image guidance by the measuring the time required for screw placement, the radiation exposure to specimen and surgeon, and the accuracy of screw position in the thoracic spine. SUMMARY OF BACKGROUND DATA: Image guidance provides additional anatomic information to the surgeon and may improve safety of technically difficult surgical procedures. The placement of screws in the thoracic spine is a technically demanding procedure in which inaccurate screw positioning places the spinal cord, nerve roots, and paraspinal structures such as the aorta and pleural space at risk for injury. Image-guided surgery may improve the accuracy of thoracic screw placement. METHODS: Using four different intraoperative imaging methods, two experienced surgeons placed 337 vertebral body screws through the pedicles of thoracic vertebrae in 20 human cadaver thoracic spine specimens. The specimens then were examined with radiographs, computed tomography, and anatomic dissection to determine screw position. Measurements included procedure setup and screw insertion time, radiation exposure to the specimen, the surgeon's hand, the surgeon's body, frequency, direction, and magnitude of screw perforation through the cortical margins of thoracic vertebrae. RESULTS: As compared with surgery using standard fluoroscopy, fluoroscopy-based image guidance that uses multiple reference marks and computed tomography-based image guidance improves the accuracy of thoracic vertebral body screws, but increases the time required for screw placement and the specimen radiation exposure. Exposure to radiation is minimal at the surgeon's body level and dependent on surgical technique at the surgeon's hand level. Screw perforation occurs most frequently in the lateral direction. CONCLUSIONS: Fluoroscopy-based image guidance that uses only a single reference marker for the entire thoracic spine is highly inaccurate and unsafe. Systems with registration based on the instrumented vertebrae provide more accurate placement of thoracic vertebral body screws than standard fluoroscopy, but expose the patient to more radiation and require more time for screw insertion.

Adult↗