Ryan D. Muchow

Magnetic resonance imaging (MRI) in the clearance of the cervical spine in blunt trauma: a meta-analysis

BACKGROUND There is a subset of blunt trauma patients that present with symptoms suspicious for cervical spine injury or with unreliable clinical exams whose initial plain radiographs or cervical computed tomography (CT) scan are negative. Uncertainty remains, however, because no gold standard has been established for definitively clearing the cervical spine of injury in this patient cohort. Individual studies have detailed the use of magnetic resonance imaging (MRI) in this patient population without conclusive results. METHODS Comprehensive database searches were conducted for prospective or retrospective diagnostic studies of blunt trauma patients who were entered into a cervical spine clearance protocol that included MRI. Inclusion criteria were minimum 30 patients with clinically suspicious or unevaluatable cervical spines, clinical follow-up as the gold standard, data reported to allow the collection of true positives, true negatives, false positives, and false negatives, MRI obtained within 72 hours of injury, and plain radiographs that disclosed nothing abnormal of the cervical spine with or without a CT scan that disclosed nothing abnormal. Log odds meta-analysis of the sensitivity, specificity, positive, and negative predictive value of MRI was performed. RESULTS Five Level I diagnostic protocols, enrolling 464 patients receiving MRI, were included. There were zero false negatives in the five studies resulting in a negative predictive value of 100%. Log odds meta-analysis produced a 94.2% positive predictive value (95% confidence interval [CI] 75.0, 989), 97.2% sensitivity (95% CI 89.5, 99.3), and 98.5% specificity (95% CI 91.8, 99.7). Ninety-seven (97 of 464, 20.9%) patients had abnormalities identified by MRI that were not identified by plain radiographs with or without CT. CONCLUSION A magnetic resonance image that did not disclose anything abnormal can conclusively exclude cervical spine injury and is established as a gold standard for clearing the cervical spine in a clinically suspicious or unevaluatable blunt trauma patient. An accurate number of false positive MRI scans cannot be determined.

Histopathologic inflammatory response induced by recombinant bone morphogenetic protein-2 causing radiculopathy after transforaminal lumbar interbody fusion

BACKGROUND CONTEXT A significant increase in off-label use of recombinant human bone morphogenic protein-2 (rhBMP-2) in posterior lumbar interbody fusion techniques has been seen in the spine community. Numerous reports have demonstrated complications with use of this proinflammatory agent; however, the in vivo response caused by rhBMP-2 has not been characterized on a cellular level. PURPOSE To report the case of lumbar radiculopathy and the associated histopathologic findings stemming from the inflammatory response to rhBMP-2 used in transforaminal lumbar interbody fusion (TLIF) surgery. STUDY DESIGN/SETTING Case report. PATIENT SAMPLE Single patient case report of rhBMP-2 off-label use causing an inflammatory response that resulted in radiculopathy after TLIF surgery. OUTCOMES MEASURES Clinical, radiologic, and histopathologic evidence was used to determine outcomes in this report. METHODS A 27-year-old male presented with low back pain and radiculopathy and radiographic evidence of degenerative disc disease and foraminal stenosis. Four weeks after L4-L5 TLIF surgery augmented with rhBMP-2, the patient developed right-sided lower extremity radiculopathy. Magnetic resonance imaging of the lumbar spine demonstrated bilateral fluid collections with the larger right-sided mass compressing the right L4 nerve root. RESULTS Surgical decompression of this mass resulted in resolution of his right-sided radicular symptoms. Histologic analysis of the surgical pathology demonstrated diffuse osteoid and woven bone amidst a fibrovascular stroma densely populated by lymphocytes and eosinophils. CONCLUSIONS Off-label rhBMP-2 use in posterior interbody fusion techniques can lead to complications. This case serves to identify potential hazards of this growth factor and highlight areas for further study to better understand its in vivo behavior.

Clearance of the asymptomatic cervical spine: a meta-analysis.

Objectives: To perform a comprehensive review of the literature and subsequent meta-analysis of data regarding appropriate clearance of the asymptomatic cervical spine in blunt trauma patients. The goal is to identify an asymptomatic patient group that can safely be cleared of cervical spine immobilization without radiographic evaluation. Data Sources: The National Library of Medicine was searched for English-language articles published between 1966 and December 2004. The key words spinal injury, spinal fracture, spinal injuries, cervical, clearance, diagnosis, and radiography were used to perform the search. Study Selection: Inclusion criteria were 1) a prospectively applied protocol; 2) reported outcomes to allow calculation of sensitivity, specificity, negative predictive value, and positive predictive value; and 3) follow up to determine the status of potential injuries with minimum of a 2-week telephone call or a computerized tomography scan. No exclusion criteria were applied. Data Extraction: The three senior authors independently confirmed the validity of the included papers for meeting appropriate criteria for the meta-analysis. True-positives, true-negatives, false-positives, and false-negatives were extracted from these studies. Data Synthesis: Original scale and log odds meta-analysis were performed using random effects methodology to calculate sensitivity, specificity, positive predictive value, and negative predictive value. Conclusions: An alert, asymptomatic patient without a distracting injury or neurologic deficit who is able to complete a functional range-of-motion examination may safely be cleared from cervical spine immobilization without radiographic evaluation (sensitivity = 98.1%, negative predictive value = 99.8%).

Theoretical increase of thyroid cancer induction from cervical spine multidetector computed tomography in pediatric trauma patients.

Background: The trend of increasing cervical spine multidirectional computed tomography (MDCT) imaging of pediatric trauma patients is characteristic of the overall dramatic increase in computed tomography utilization in the United States. The purpose of this study is to compare the amount of radiation a pediatric trauma patient absorbs to the thyroid from plain radiographs and MDCT of the cervical spine and to express risk by calculation of theoretical thyroid cancer induction. Methods: A retrospective evaluation of pediatric trauma patients admitted from October 1, 2004, to October 31, 2009, was performed at an academic, Level I trauma center. Inclusion criteria were Level I/II trauma patients, cervical spine imaging performed at our institution, and age <18 years. Absorbed thyroid radiation was calculated for patients receiving plain radiographs or MDCT. Thyroid cancer risk was calculated using the 2006 Biological Effects on Ionizing Radiation VII report. Results: Six hundred seventeen patients met inclusion criteria: 224 received cervical spine radiographs and 393 received cervical spine MDCT. The mean thyroid radiation absorbed from radiographs was 0.90 mGy for males and 0.96 mGy for females compared with 63.6 mGy (males) and 64.2 mGy (females) receiving MDCT (p < 0.001). The median excess relative risk of thyroid cancer induction from one cervical spine MDCT in males was 13.0% and females was 25.0%, compared with 0.24% (males) and 0.51% (females) for radiographs (p < 0.001). Conclusions: The significant difference in radiation that MDCT delivers to the pediatric trauma patient when compared with plain radiographs should temper routine use of computed tomography in pediatric cervical spine clearance algorithms.

The results of preoperative halo-gravity traction in children with severe spinal deformity.

Halo-gravity traction has been used preoperatively for patients with severe spinal deformity but there are limited data in the literature on the results and complications. We studied the outcomes of perioperative halo-gravity traction in children with severe spinal deformity. A retrospective study was carried out on patients who were treated at our center. Twenty-one patients were included in the study. Radiographic and pulmonary function parameters showed significant improvement during the course of traction and at the final follow-up. The overall complication rate was 19%, including two patients with pin loosening and two patients with superficial pin-site infections treated with oral antibiotics.

Factors predictive of second recurrence in clubfeet treated by ponseti casting.

Background: Ponseti serial casting is the most commonly used method in North America to treat children with clubfeet. Despite initial correction, recurrence is common. tibialis anterior tendon transfer (TATT) is commonly used to treat recurrent clubfeet. Recurrence can occur after TATT, and patients at risk of recurrence may benefit from closer monitoring. We studied the rate of second recurrence (recurrence after TATT) and studied the predictive factors for this recurrence. Methods: Retrospective chart review of patients who have undergone TATT for recurrent clubfeet between 2002 and 2010 at our institution was performed. Recurrence was defined as recurrence of any elements of the clubfoot deformity that requires operative or nonoperative treatment. Effect of age at the time of TATT, initial severity of the deformity, and family history of clubfoot on rate of recurrence was studied. Results: Sixty patients with 85 clubfeet were included in the study. Sixteen feet in 12 patients (20%) developed recurrence after TATT. Eight feet were treated nonoperatively and the rest (8 feet) required surgical procedure. Young age at time of TATT and brace noncompliance significantly increased the rate of second recurrence. Effect of severity of initial deformity and family history did not reach statistical significance. Conclusions: Second recurrence can happen in around one fifth of patients with clubfeet after TATT. Patients with young age at TATT and patients with brace noncompliance are at an increased risk of recurrence and should be monitored closely. Level of Evidence: Level II—prognostic.

Syringomyelia and vertebral osteochondromas in patients with multiple hereditary exostosis.

Involvement of osteochondromas in the spinal canal occurs in patients with multiple hereditary exostosis, but the exact prevalence is unknown. A recent study found an incidence of 68%, with 27% of these lesions encroaching into the spinal canal. We studied MRI findings of 27 patients with multiple hereditary exostosis and found only six (23.1%) patients with osteochondromas arising from the spinal column and three (11.5%) patients with encroachment into the spinal canal. We also found three (11.5%) patients with an incidental syringomyelia. Only five of the nine (55.6%) patients with positive findings on MRI had symptoms prompting the MRI and two patients had significant symptoms that required surgical excision. Although the incidence of spinal osteochondroma in our population is lower than that of previous studies, we found a relatively high incidence of syringomyelia in these patients, which has not been previously reported.

Initial Correction Predicts the Need for Secondary Achilles Tendon Procedures in Patients With Idiopathic Clubfoot Treated With Ponseti Casting.

Background: The Ponseti method is the most common method to treat idiopathic clubfoot in North America. Despite initial correction, recurrence is common with this method. The factors predictive of recurrence are not well defined in the literature. Methods: A retrospective chart review was done of procedures performed at our institution from 2005 to 2010 in children undergoing general anesthesia for primary percutaneous Achilles tenotomy for the treatment of idiopathic clubfoot using the Ponseti casting method (101 patients, 148 feet). All patients were followed up for at least 2 years postoperatively (2 to 7.5 y, average 3.5 y). The patients were divided into 2 groups: group N with no repeat procedures on Achilles tendon and group R with a secondary procedure to address the residual equinus deformity. We looked at postoperative equinus correction through the use of postoperative measurements on digital images using a goniometer. The amount of postoperative dorsiflexion at the initial procedure was compared between the 2 groups using the paired t test. The feet were then divided into 3 groups on the basis of the amount of initial correction, and the rates of future surgical procedures were compared among these groups. Results: A total of 101 patients (148 feet) were evaluated. Seventy-two patients (106 feet) did not have any future procedures to address equinus deformity (group N). Twenty-nine patients (42 feet) underwent future procedure (group R) to correct the residual equinus. The N and R groups differed in amount of postoperative dorsiflexion (14.0 vs. 5.1; P<0.01). Patients in whom at least 10 degrees of dorsiflexion was achieved after the initial tenotomy had only a 12% rate of future procedures. Patients with neutral or less than neutral dorsiflexion had 64% chance of future procedures to address the residual equinus. Conclusions: Residual equinus deformity after Achilles tenotomy in clubfeet treated by the Ponseti method is associated with a high rate of future surgical procedures. Correction of this deformity before bracing could potentially decrease the rate of future surgery. Level of Evidence: Level III—Retrospective.

Residual forefoot deformity predicts the need for future surgery in clubfeet treated by Ponseti casting.

Tibialis anterior tendon transfer (TATT) is performed for treatment of recurrent clubfeet. We investigated the predictability of residual adductus on the future need for TATT. A retrospective review of 143 patients with clubfoot was performed. The patients were divided into two groups: group 1 with a history of TATT and group 2 with no TATT. Heel-forefoot angle (HFA) was measured. HFA was compared between the groups. HFA was significantly different between groups 1 and 2. Residual adductus deformity in clubfeet treated by Ponseti casting is a risk factor for future need for surgical treatment.

Efficacy of 2 Regional Pain Control Techniques in Pediatric Foot Surgery.

Background: Peripheral nerve blocks (PNBs) have the potential to reduce postoperative pain. The use of ultrasound (US) to guide PNBs may be more beneficial than nerve stimulation (NS); however, very few studies have studied this technique in children. The objective of this study was to compare postoperative pain control in pediatric patients who had general anesthesia (GA) alone compared with those who had PNB performed by NS, or PNB with both NS and US guidance. Our hypothesis was that compared with NS, the US-guided PNB would result in reduced postoperative pain and opioid use, and that both PNB conditions would have improved outcomes compared with GA. Methods: A retrospective chart review of foot and ankle surgery included 103 patients who were stratified into 3 groups: GA, PNB with NS, and PNB with NS and US. Pain levels were measured with visual pain scales at 2, 4, 6, 8, 12, and 24 hours postoperatively. Days of hospitalization, morphine and oxycodone use by weight, and time to first PRN opioid use were also recorded. A repeated measure analysis of variance was used to compare the groups, and the proportion of patients who reported a visual analog scale score of 0 was calculated for each time point. Results: There were no significant differences in pain levels between groups for the first 12 hours, but the US group had higher pain levels at 24 hours. Both US and NS groups had a longer time to PRN opioid use and used significantly less morphine compared with GA. The US group had a significantly greater proportion of pain-free patients than the other 2 groups for the first 6 hours. Conclusions: The use of US guidance is beneficial in postoperative pain control. Both US-guided and NS-guided PNB are preferable to GA alone for lower extremity orthopaedic surgery in the pediatric population. Level of Evidence: III, retrospective comparative study.