Bone morphogenetic protein in spine surgery: current and future uses.

The clinical use of bone morphogenetic protein (BMP) in spinal fusion surgery has recently become controversial. After its approval by the US FDA in July 2002, BMP was adopted by many spine surgeons as a replacement for the more traditional iliac crest bone graft to avoid the complications associated with bone graft harvest. However, as broad clinical use escalated, reports increased of potentially serious complications associated with BMP. Controversy continues, particularly regarding the safety of BMP and whether it should routinely replace iliac crest bone graft for spinal fusion surgery.

The Evaluation of Donor Site Pain After Harvest of Tricortical Anterior Iliac Crest Bone Graft for Spinal Surgery: A Prospective Study.

STUDY DESIGN: A prospective cohort. OBJECTIVE: The aim of this study was to prospectively observe donor site pain, health-related quality-of-life outcomes, and complications following harvest of tricortical anterior iliac crest bone graft (AICBG) for anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: Persistent donor site pain from the anterior iliac crest has been reported to range between 2% and 40%. This morbidity has led surgeons to consider interbody alternatives for ACDF, which carry additional costs. METHODS: We prospectively enrolled 50 patients from 2 tertiary care centers over the course of 1 year observing complications and patient-reported outcomes. Patients filled out SF-12 and numeric rating scale (NRS) for pain in the arm, neck, and donor site pre-operatively and at 1 week, 2 weeks, 6 weeks, 3 to 6 months, and 1 year postoperatively. Outcomes were compared with a control group undergoing ACDF with allograft or Polyether ether ketone cages at 1 year. RESULTS: The mean ±â€ŠSD donor site pain at 1 week was 5.6 ±â€Š2.8 but decreased to 2.2 ±â€Š2.4 at 6 weeks and 1.1 ±â€Š1.8 at 1 year (P < 0.001). Including the 3 patients who were lost to follow-up, 10% of patients may have experienced persistent moderate or worse pain at 1 year. Linear regression analysis demonstrated that preoperative opioid use was an independent risk factor for increased donor site pain at 1 and 2 weeks (P < 0.05). There were no differences in outcomes at 1 year compared with the nonautograft group. There were 2 (4%) minor wound complications, both treated successfully with oral antibiotics. CONCLUSION: Tricortical AICBG for ACDF is not associated with major complications and only 4% of patients (potentially, maximum of 10%) experienced moderate, persistent donor site pain at 1 year. There is no difference in health-related outcomes between patients who have autograft with those who did not at 1 year. Preoperative opioid use is associated with increased donor site pain within the first 2 weeks postoperatively but not in the long term. At 6 weeks postoperatively, patients can expect the majority of their donor site pain to be resolved. LEVEL OF EVIDENCE: 2.

Imaging characteristics of "dynamic" versus "static" spondylolisthesis: analysis using magnetic resonance imaging and flexion/extension films.

BACKGROUND CONTEXT: Traditionally, the "dynamic" and "static" types of spondylolisthesis have been lumped into a single group in the literature. The goal of this study was to define the radiographic characteristics of "dynamic" and "static" spondylolisthesis with the use of magnetic resonance imaging (MRI) and flexion/extension radiographs. PURPOSE: Describe the characteristic findings present on MRI and flexion/extension radiographs that are associated with dynamic versus static spondylolisthesis. STUDY DESIGN: Retrospective radiographic/imaging study. METHODS: From 2009 to 2011, patients who underwent elective primary posterior spinal fusion for the diagnosis of spondylolisthesis had their plain films assessed for the degree of spondylolisthesis and were designated "dynamic" or "static," as defined by historical measures. Axial and sagittal T2 MRIs were evaluated for associated facet fluid (FF), facet cysts, interspinous fluid (ISF), and facet hypertrophy. These finding were then statistically evaluated for associations between dynamic and static spondylolisthesis on flexion/extension radiographs and characteristic MRI findings. RESULTS: Ninety patients were included in the study with 114 levels examined for spondylolisthesis. Patients with greater than 3 mm of instability on flexion/extension films were more likely to have FF (p=.018) and ISF (p<.001). Of the patients who had a greater than 3 mm of instability, 39.5% did not demonstrate spondylolisthesis on the sagittal MRI reconstruction. If ISF was present on MRI, there was a positive predictive value of 69.0% that there would be greater than 3 mm instability on flexion/extension films. Absence of FF on MRI had a positive predictive value of 75.6% for instability less than 3 mm on flexion/extension films. In the presence of ISF on MRI, the likelihood ratio of finding more than 3 mm of instability on flexion/extension films was 3.68. The presence of FF on MRI had a likelihood ratio of 1.43 for instability. A total of 36.8% of all spondylolisthesis reduced when supine on MRI. CONCLUSIONS: The presence of FF and/or ISF is associated with instability greater than 3 mm in flexion/extension radiographs.

Vertebral artery injuries in cervical spine surgery.

BACKGROUND CONTEXT: Vertebral artery injuries (VAIs) are rare but serious complications of cervical spine surgery, with the potential to cause catastrophic bleeding, permanent neurologic impairment, and even death. The present literature regarding incidence of this complication largely comprises a single surgeon or small multicenter case series. PURPOSE: We sought to gather a large sample of high-volume surgeons to adequately characterize the incidence and risk factors for VAI, management strategies used, and patient outcomes after VAI. STUDY DESIGN: The study was constructed as a cross-sectional study comprising all cervical spine patients operated on by the members of the international Cervical Spine Research Society (CSRS). PATIENT SAMPLE: All patients who have undergone cervical spine surgery by a current member of CSRS as of the spring of 2012. OUTCOME MEASURES: For each surgeon surveyed, we collected self-reported measures to include the number of cervical cases performed in the surgeon's career, the number of VAIs encountered, the stage of the case during which the injury occurred, the management strategies used, and the overall patient outcome after injury. METHODS: An anonymous 10-question web-based survey was distributed to the members of the CSRS. Statistical analysis was performed using Student t tests for numerical outcomes and chi-squared analysis for categorical variables. RESULTS: One hundred forty-one CSRS members (of 195 total, 72%) responded to the survey, accounting for a total of 163,324 cervical spine surgeries performed. The overall incidence of VAI was 0.07% (111/163,324). Posterior instrumentation of the upper cervical spine (32.4%), anterior corpectomy (23.4%), and posterior exposure of the cervical spine (11.7%) were the most common stages of the case to result in an injury to the vertebral artery. Discectomy (9%) and anterior exposure of the spine (7.2%) were also common time points for an arterial injury. One-fifth (22/111) of all VAI involved an anomalous course of the vertebral artery. The most common management of VAI was by direct tamponade. The outcomes of VAIs included no permanent sequelae in 90% of patients, permanent neurologic sequelae in 5.5%, and death in 4.5%. Surgeons at academic and private centers had nearly identical rates of VAIs. However, surgeons who had performed 300 or fewer cervical spine surgeries in their career had a VAI incidence of 0.33% compared with 0.06% in those with greater than 300 lifetime cases (p=.028). CONCLUSIONS: The overall incidence of VAI during cervical spine surgery reported from this survey was 0.07%. Less experienced surgeons had a higher rate of VAI compared with their more experienced peers. The results of VAI are highly variable, resulting in no permanent harm most of the time; however, permanent neurologic injury or death occur in 10% of cases.

Effects of epidural steroid injections on blood glucose levels in patients with diabetes mellitus.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: To evaluate the effects of epidural steroid injections (ESIs) on blood glucose levels in patients with diabetes mellitus. SUMMARY OF BACKGROUND DATA: ESIs are commonly used in the treatment of multiple spinal disorders. Corticosteroid injections have been evaluated in the total joints and hand literature showing systemic effects to diabetics. METHODS: Diabetic patients who were scheduled for an ESI were given an opportunity to enroll in our IRB-approved study. We collected the patient's most recent hemoglobin A(1c) (hA(1c)) and then asked them to track their blood glucose numbers at least twice per day for 2 weeks prior to and after their ESIs. RESULTS: We noted a statistically significant increase in blood glucose levels in diabetic patients (n = 30) after ESI. The mean blood glucose level prior to ESI was 160.18 ± 47.46, and, after ESI, it was 286.13 ± 111.11. This represents an average 125.96 ± 100.97 increase in blood glucose levels after injection. Using a nonlinear mixed effect model, the estimated half-life of this increase was 1.06 days (95% CI 0.80, 1.58), meaning that the patients were back within their normal standard deviation mean glucose levels within 2 days of injection. There was no association between observed glucose level change and preinjection hA(1c) levels or age (Spearman = 0.0326 and -0.1091 separately), indicating that there is no correlation between preinjection hA(1c) levels and systemic response to ESI. CONCLUSION: ESIs were noted to cause a significant increase in the blood glucose levels in diabetics. There was no correlation between preinjection diabetic control, represented by hA(1c) levels, and postinjection response. Diabetics who are candidates for ESI should be counseled that a blood glucose increase may be apparent post intervention, but effects should not last longer than approximately 2 days.

Clinical indications for arterial imaging in cervical trauma.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To evaluate the clinical indications for acquiring arterial imaging in cervical trauma. SUMMARY OF BACKGROUND DATA: Cervical spine injuries are very common in high-energy trauma and are frequently seen at Level I trauma centers across the country. A clinical standard of care does not exist to indicate when further evaluation of the cervical vasculature is warranted after a documented cervical spine injury. METHODS: After institutional review board approval, a retrospective study combining the data from 2 Level I trauma centers was undertaken. An evaluation of every arterial imaging procedure (computed tomography and magnetic resonance angiography) of the cervical spine was collected to further delineate indications and outcomes of these imaging modalities. RESULTS: From 2005 to 2009, there were a total of 159 patients who underwent cervical arterial imaging at the 2 participating institutions for the indication of cervical trauma with concern for arterial injury. Thirty-six (22.64%) were found to have an injury after arterial imaging. There was a statistically significant correlation with displaced cervical injuries (P < 0.0153), which were defined as cervical dissociations or perched and/or jumped facets. The other statistically significant correlation was the presence of a neurological deficit (P < 0.001), defined as any presenting deficit on sensory or motor examination. Level of injury defined as axial (O-C2) versus subaxial (C3-C7), age, body mass index, and history of cigarette smoking were not statistically related to vascular injury. CONCLUSION: Our retrospective evaluation indicates that there should be a lower threshold for obtaining arterial imaging with cervical injury patterns historically known to compromise the vasculature, which also have concomitant displaced cervical spine injuries and/or a neurological deficit.

Preoperative skeletal versus cutaneous traction for femoral shaft fractures treated within 24 hours.

OBJECTIVES: To compare the advantages and disadvantages of preoperative cutaneous traction versus skeletal traction in adults with diaphyseal femur fractures amenable to fixation within 24 hours. DESIGN: Randomized prospective trial. SETTING: Level I trauma center in a major metropolitan area. PATIENTS: Sixty-five patients with 66 femur fractures were prospectively enrolled and randomized to a traction group from July 2009 to July 2010. MAIN OUTCOME MEASUREMENTS: Time of application for on call physicians/practitioners, pain relief after application of traction; time of reduction in the operating room theater, and evaluation of pain medication consumption before stabilization. RESULTS: Thirty-seven patients received cutaneous femoral traction, whereas 29 patients received skeletal traction. There was a significant reduction in time of application for the cutaneous traction (24.30 ± 24.74 minutes) compared with skeletal traction (57.10 ± 33.60 minutes) (P ≤ 0.001). There was no statistically significant difference in visual analog scale (VAS) scores when compared with pretraction application pain assessment and posttraction pain assessment between the cutaneous and skeletal traction groups with a decrease in the VAS of (0.56 ± 3.73 and 0.54 ± 2.76), respectively (P = 0.99). There was no difference in pain medication requirements between groups (0.12 ± 0.17 mg/kg for cutaneous versus 0.09 ± 0.14 mg/kg for skeletal, P = 0.39). There was no significant difference in reduction time of the fracture (skin incision or opening reamer to guide wire passage) in the operating room between cutaneous traction versus skeletal traction (P = 0.59). CONCLUSIONS: Use of cutaneous traction for diaphyseal femur fractures when compared with skeletal traction results in a statistically significant reduction in time of application to the on call practitioner with no complications or detrimental change in operative time and no difference in VAS pain scores or narcotic usage.

Diagnostic abilities of magnetic resonance imaging in traumatic injury to the posterior ligamentous complex: the effect of years in training.

BACKGROUND CONTEXT: The integrity of the posterior ligamentous complex (PLC) has been proposed to be an integral aspect in the treatment algorithm for spinal trauma. Magnetic resonance imaging (MRI) has been reported as the ideal tool to determine the integrity of the PLC. The ability to assess disruption of the PLC by reviewers of differing levels of training has not been described. In addition, the MRI sequence most suggestive of injury for each component of the PLC has not been clearly determined. PURPOSE: This study was designed to determine the ability of reviewers with differing levels of training (fellowship-trained spine surgeon, fellowship-trained musculoskeletal radiologist, senior orthopedic surgery resident, and junior orthopedic surgery resident) to accurately interpret the results of MRI. The secondary purpose was to evaluate the MRI sequence that was most indicative of injury to the components of the PLC. STUDY DESIGN: This is a prospective radiological study comparing reviewers of MRI to determine integrity of the PLC components using intraoperative notation as the gold standard for integrity. PATIENT SAMPLE: Forty-five consecutive spinal trauma patients who underwent operative fixation after obtaining MRI. OUTCOME MEASURES: No patient outcome measures were used. METHODS: The sensitivity, specificity, and accuracy for each MRI reviewer in regard to MRI integrity were compared with the gold standard of intraoperative observation. In addition, the MRI sequence most suggestive of integrity of the PLC was noted by each reviewer for each component of the PLC. RESULTS: Forty-five patients (29 men and 16 women) with traumatic spine injuries were enrolled in the study. The sensitivity and accuracy of the surgeon were 0.83 (0.66, 0.92) and 0.81 (0.70, 0.88), respectively. The sensitivity and accuracy of the attending spine surgeon were not statistically significantly different from the other reviewers (p value=.2317 and .2582). However, the specificity of the surgeon was statistically significantly higher than that of the other reviewers (p=.0043). In the cervical, thoracic, and lumbar spine, the reviewers reached a 93% agreement that the sagittal short-tau inversion recovery (STIR) sequences were most helpful in visualizing injury to the supraspinous ligament (SSL), interspinous ligament (ISL), ligamentum flavum (LF), and the cervical facet capsules. The reviewers attained a 95% agreement that visualization of injury to the lumbar facet capsules is most optimal in the T2 axial sequences. CONCLUSIONS: The interpretation of traumatic MRI is very sensitive and accurate regardless of years of training of the observer. The attending-level spine surgeon was statistically more specific in the evaluation of injury MRIs. The fluid-weighted STIR sagittal sequences are most useful in determining injury to the SSL, ISL, LF, and cervical facets capsules. Lumbar facet capsules are best evaluated with axial T2 MRI. The evaluation of the PLC on MRI can be accurately and efficiently interpreted by physicians at multiple levels of training, thus providing a key imaging modality in determining stability and need for stabilization.

Increasing duration of type 1 diabetes perturbs the strength-structure relationship and increases brittleness of bone.

Type 1 diabetes (T1DM) increases the likelihood of a fracture. Despite serious complications in the healing of fractures among those with diabetes, the underlying causes are not delineated for the effect of diabetes on the fracture resistance of bone. Therefore, in a mouse model of T1DM, we have investigated the possibility that a prolonged state of diabetes perturbs the relationship between bone strength and structure (i.e., affects tissue properties). At 10, 15, and 18 weeks following injection of streptozotocin to induce diabetes, diabetic male mice and age-matched controls were examined for measures of skeletal integrity. We assessed 1) the moment of inertia (I(MIN)) of the cortical bone within diaphysis, trabecular bone architecture of the metaphysis, and mineralization density of the tissue (TMD) for each compartment of the femur by micro-computed tomography and 2) biomechanical properties by three-point bending test (femur) and nanoindentation (tibia). In the metaphysis, a significant decrease in trabecular bone volume fraction and trabecular TMD was apparent after 10 weeks of diabetes. For cortical bone, type 1 diabetes was associated with decreased cortical TMD, I(MIN), rigidity, and peak moment as well as a lack of normal age-related increases in the biomechanical properties. However, there were only modest differences in material properties between diabetic and normal mice at both whole bone and tissue-levels. As the duration of diabetes increased, bone toughness decreased relative to control. If the sole effect of diabetes on bone strength was due to a reduction in bone size, then I(MIN) would be the only significant variable explaining the variance in the maximum moment. However, general linear modeling found that the relationship between peak moment and I(MIN) depended on whether the bone was from a diabetic mouse and the duration of diabetes. Thus, these findings suggest that the elevated fracture risk among diabetics is impacted by complex changes in tissue properties that ultimately reduce the fracture resistance of bone.

Eye protection in orthopaedic surgery. An in vitro study of various forms of eye protection and their effectiveness.

BACKGROUND: Conjunctival contamination from splashed debris during orthopaedic surgical procedures places surgeons at risk for communicable diseases such as human immunodeficiency virus (HIV) and hepatitis B and C. The purpose of this study was to compare the effectiveness of various types of protective eyewear in preventing conjunctival contamination. METHODS: A simulation model was constructed with use of a mannequin head in a typical position of a surgeon's head during an operation. The head was placed at an appropriate distance from the surgical field, and a femoral osteotomy was performed on a cadaver thigh. Six experimental groups were tested to determine the ability of various types of eye protection to prevent contamination of the conjunctiva: (1) modern prescription glasses, (2) standard surgical telescopic loupes, (3) hard plastic contoured glasses, (4) disposable plastic glasses, (5) a combination facemask and eye shield, and (6) no protection (control). Thirty femoral osteotomies were performed, and contamination of both the protective devices and the simulated conjunctival surfaces were recorded. RESULTS: None of the tested devices were completely effective. The modern prescription glasses and the controls both were associated with conjunctival contamination rates of 83%. The other eye protective devices were associated with significantly lower rates of overall contamination, with a rate of 50% for the loupes, 30% for the facemask and eye shield, 17% for the hard plastic glasses, and 3% for the disposable plastic glasses. CONCLUSIONS: Modern prescription glasses provided no benefit over the control in our experimental model; therefore, we do not recommend that they be used as the sole eye protection, especially during surgical procedures in which there is a high rate of debris expulsion from the wound. Readily available and disposable plastic glasses were associated with the lowest rate of conjunctival contamination (3%) and are an effective means with which to protect the orthopaedic surgeon from communicable diseases by conjunctival contamination.