Rare Complications of Cervical Spine Surgery: Horner's Syndrome.

STUDY DESIGN: A multicenter retrospective case series. OBJECTIVE: Horner's syndrome is a known complication of anterior cervical spinal surgery, but it is rarely encountered in clinical practice. To better understand the incidence, risks, and neurologic outcomes associated with Horner's syndrome, a multicenter study was performed to review a large collective experience with this rare complication. METHODS: We conducted a retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. Paired t test was used to analyze changes in clinical outcomes at follow-up compared to preoperative status. RESULTS: In total, 8887 patients who underwent anterior cervical spine surgery at the participating institutions were screened. Postoperative Horner's syndrome was identified in 5 (0.06%) patients. All patients experienced the complication following anterior cervical discectomy and fusion. The sympathetic trunk appeared to be more vulnerable when operating on midcervical levels (C5, C6), and most patients experienced at least a partial recovery without further treatment. CONCLUSIONS: This collective experience suggests that Horner's syndrome is an exceedingly rare complication following anterior cervical spine surgery. Injury to the sympathetic trunk may be limited by maintaining a midline surgical trajectory when possible, and performing careful dissection and retraction of the longus colli muscle when lateral exposure is necessary, especially at caudal cervical levels.

Anterior Cervical Infection: Presentation and Incidence of an Uncommon Postoperative Complication.

STUDY DESIGN: Retrospective multi-institutional case series. OBJECTIVE: The anterior cervical discectomy and fusion (ACDF) affords the surgeon the flexibility to treat a variety of cervical pathologies, with the majority being for degenerative and traumatic indications. Limited data in the literature describe the presentation and true incidence of postoperative surgical site infections. METHODS: A retrospective multicenter case series study was conducted involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network, selected for their excellence in spine care and clinical research infrastructure and experience. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, inclusive, were reviewed to identify the occurrence of 21 predefined treatment complications. Patients who underwent an ACDF were identified in the database and reviewed for the occurrence of postoperative anterior cervical infections. RESULTS: A total of 8887 patients were identified from a retrospective database analysis of 21 centers providing data for postoperative anterior cervical infections (17/21, 81% response rate). A total of 6 postoperative infections after ACDF were identified for a mean rate of 0.07% (range 0% to 0.39%). The mean age of patients identified was 57.5 (SD = 11.6, 66.7% female). The mean body mass index was 22.02. Of the total infections, half were smokers (n = 3). Two patients presented with myelopathy, and 3 patients presented with radiculopathic-type complaints. The mean length of stay was 4.7 days. All patients were treated aggressively with surgery for management of this complication, with improvement in all patients. There were no mortalities. CONCLUSION: The incidence of postoperative infection in ACDF is exceedingly low. The management has historically been urgent irrigation and debridement of the surgical site. However, due to the rarity of this occurrence, guidance for management is limited to retrospective series.

Esophageal Perforation Following Anterior Cervical Spine Surgery: Case Report and Review of the Literature.

STUDY DESIGN: Multicenter retrospective case series and review of the literature. OBJECTIVE: To determine the rate of esophageal perforations following anterior cervical spine surgery. METHODS: As part of an AOSpine series on rare complications, a retrospective cohort study was conducted among 21 high-volume surgical centers to identify esophageal perforations following anterior cervical spine surgery. Staff at each center abstracted data from patients' charts and created case report forms for each event identified. Case report forms were then sent to the AOSpine North America Clinical Research Network Methodological Core for data processing and analysis. RESULTS: The records of 9591 patients who underwent anterior cervical spine surgery were reviewed. Two (0.02%) were found to have esophageal perforations following anterior cervical spine surgery. Both cases were detected and treated in the acute postoperative period. One patient was successfully treated with primary repair and debridement. One patient underwent multiple debridement attempts and expired. CONCLUSIONS: Esophageal perforation following anterior cervical spine surgery is a relatively rare occurrence. Prompt recognition and treatment of these injuries is critical to minimizing morbidity and mortality.

Misplaced Cervical Screws Requiring Reoperation.

STUDY DESIGN: A multicenter, retrospective case series. OBJECTIVE: In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication. METHODS: A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center. RESULTS: A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%). CONCLUSIONS: This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication.

Does Planned Staging for Posterior-Only Vertebral Column Resections in Spinal Deformity Surgery Increase Perioperative Complications?

STUDY DESIGN: Propensity-matched case control. OBJECTIVES: To compare the perioperative complication rate between single- and two-stage posterior-only VCRs (2-pVCR). SUMMARY OF BACKGROUND DATA: A vertebral column resection (VCR) for severe spinal deformity is a technically challenging and lengthy procedure with a potentially high complication rate. Planned staging has an advantage of distributing operative time into 2 smaller, more manageable, intervals. METHODS: Adult and pediatric spinal deformity patients undergoing a VCR were retrospectively identified from a single institution's surgical database from 1985 to 2013. Propensity scoring was used to match 2-pVCR and single-staged patients. Each group was matched for 15 preoperative risk factors including demographic, operative, and radiographic characteristics. Perioperative complications were defined as occurring within 2 months of initial surgery. Additionally, a binary logistic regression analysis was performed with complications as the outcome. RESULTS: A total of 183 consecutive patients were identified as undergoing a VCR, with 172 meeting the inclusion criteria (posterior-only). Forty-four patients underwent planned 2-pVCR whereas 124 had a single-staged VCR. Consistent with propensity-matching, no statistically significant difference between the single- and 2-pVCR cohorts existed for all matching parameters, except pulmonary function tests. There was no significant difference (p = .290) between complication rates for single-stage (12/35; 34%) and 2-pVCR (8/35; 23%) patients. Stepwise binary logistic regression analysis showed that age (p = .014; OR = 0.94, CI = 0.89-0.99) and body mass index (p = .030; OR = 1.13 CI = 1.01-1.26) influenced the occurrence of a complication. CONCLUSION: Planned staging of posterior-only VCRs does not increase the occurrence of perioperative complications in adult and pediatric spinal deformity patients. LEVEL OF EVIDENCE: III (Propensity-matched case control).

Sagittal alignment as a predictor of clinical adjacent segment pathology requiring surgery after anterior cervical arthrodesis.

BACKGROUND CONTEXT: Postoperative malalignment of the cervical spine may alter cervical spine mechanics and put patients at risk for clinical adjacent segment pathology requiring surgery. PURPOSE: To investigate whether a relationship exists between cervical spine sagittal alignment and clinical adjacent segment pathology requiring surgery (CASP-S) following anterior cervical fusion (ACF). STUDY DESIGN: Retrospective matched study. PATIENT SAMPLE: A total of 122 patients undergoing ACF between 1996 and 2008 were identified, with a minimum of 2 years of follow-up. OUTCOME MEASURES: Radiographs were reviewed to measure the sagittal alignment using C2 and C7 sagittal plumb lines, distance from the fusion mass plumb line to the C2 and C7 plumb lines, the alignment of the fusion mass, caudally adjacent disc angle, the sagittal slope angle of the superior end plate of the vertebra caudally adjacent to the fusion mass, T1 sagittal angle, overall cervical sagittal alignment, and curve patterns by Katsuura classification. METHODS: A total of 122 patients undergoing ACF between 1996 and 2008 were identified, with a minimum of 1 year of follow-up. Patients were divided into groups according to the development of CASP (control/CASP-S) and by number/location of levels fused. Radiographs were reviewed to measure the sagittal alignment using C2 and C7 sagittal plumb lines, distance from the fusion mass plumb line to the C2 and C7 plumb lines, the alignment of the fusion mass, caudally adjacent disc angle, the sagittal slope angle of the superior end plate of the vertebra caudally adjacent to the fusion mass, T1 sagittal angle, overall cervical sagittal alignment, and curve patterns by Katsuura classification. Appropriate statistical tests were performed to calculate relationships between the variables and the development of CASP-S. No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this article. RESULTS: The groups were similar with regard to demographic and surgical variables. Lordosis was preserved in 82% (50/61) of the control group but in only 66% (40/61) of the CASP-S group (p=.033). More patients with a straight curve pattern developed CASP-S. The distance from the C2 to the C7 plumb line and T1 sagittal slope angle were lower in the CASP-S group with C5-C6 fusions compared with the control group. Also, the distance from C5-C6 fusion mass to C7 plumb line and C7 sagittal slope angle were lower in the CASP-S group with C5-C6 fusions. CONCLUSIONS: Our results suggest that malalignment of the cervical spine following an ACF at C5-C6 has an effect on the development of clinical adjacent segment pathology requiring surgery.

Surgical treatment of C3 and C4 cervical radiculopathies.

STUDY DESIGN: Case series study. OBJECTIVE: To report the results of surgical intervention in a series of patients with high cervical radiculopathy. SUMMARY OF BACKGROUND DATA: Although midcervical (C5-C7) radiculopathy is common and well recognized, high cervical (C3 and C4) radiculopathy is relatively rare and can be missed clinically. To our knowledge, there are few reports regarding the operative treatment of high cervical radiculopathy. METHODS: Two spine surgeons independently reviewed the charts and radiographs of all patients with high cervical radiculopathy or myeloradiculopathy that were surgically treated by the senior author. Dates of inclusion were from July 1997 to March 2008. All patients were observed for either a minimum of 2 years or until they achieved a fusion. Neck Disability Index scores were calculated pre- and postoperatively, when available, and Odom criteria were assessed for all patients. RESULTS: Twenty-three patients met the inclusion criteria. The mean follow-up period was 4.2 years (1-11.3 yr). The levels involved were C2-C3 (2 patients), C2-C4 (4 patients), and C3-C4 (17 patients). The most common symptom was suboccipital neck pain/headache with or without radiation to the retroauricular or retro-orbital region (21 patients). Preoperative neuroradiological findings were central stenosis with herniated nucleus pulposus, foraminal stenosis with uncinate hypertrophy or facet arthrosis, spondylolisthesis, and pseudarthrosis. Operative treatments included anterior cervical discectomy and fusion, posterior foraminotomy, posterior laminectomy-foraminotomy with fusion, posterior laminoplasty with fusion, and anterior/posterior combined decompression and fusion. By Odom criteria, 12 had excellent results, 8 had good results, 2 had satisfactory results, and 1 had a poor result. One patient underwent a reoperation for pseudarthrosis. CONCLUSION: Surgical treatment of high cervical radiculopathies resulted in acceptable outcomes. To our knowledge, this is the largest series of this relatively rare condition.

Improving bone density at the rotator cuff footprint increases supraspinatus tendon failure stress in a rat model.

The purpose of this study was to investigate whether supraspinatus tendon failure stress at the footprint can increase by improving the bone density at the rotator cuff footprint in a rat model. Bilateral ovariectomies were performed in twenty-four 4-month-old Sprague-Dawley rats. Half received bisphosphonate (zoledronic acid) and the other half received no treatment (OVX + ZOM and OVX, respectively). Twelve additional rats did not undergo ovariectomy or receive bisphosphonate treatment (CON). All rats were sacrificed at 7 months of age. Quantitative micro-computed tomography was used to assess bone density in the proximal humerus. A series of stress-relaxation tests were performed to assess stiffness and failure stress of the supraspinatus tendon. Bone density in OVX + ZOM was significantly higher at the rotator cuff footprint when compared to CON and OVX rats (p < 0.0001). The supraspinatus tendons in the OVX group were significantly stiffer when compared to the CON and OVX + ZOM groups (p < 0.05). The failure stress of the OVX + ZOM group was significantly greater than the CON and OVX groups (22.89 +/- 4.43 MPa vs. 18.36 +/- 3.16 and 17.70 +/- 4.92, respectively). In conclusion, improving the bone density at the rotator cuff footprint enhances failure stress of the suprapinatus tendon.

Reduction of particle-induced osteolysis by interleukin-6 involves anti-inflammatory effect and inhibition of early osteoclast precursor differentiation.

The goal of this study was to define the anti-osteoclastogenic and/or anti-inflammatory role of IL-6 in inflammatory bone resorption using in vivo and in vitro methods. To this end, titanium particles were placed on murine calvaria, and bone resorption and osteoclast formation quantified in wild-type and IL-6(-/-) mice. In this model, calvarial bone loss and osteoclast formation were increased in titanium-treated IL-6(-/-) mice. Although basal numbers of splenic osteoclast precursors (OCP) were similar, IL-6(-/-) mice treated with particles in vivo had increased splenic OCP suggesting an enhanced systemic inflammatory response. In vitro osteoclastogenesis was measured using splenic (OCP) at various stages of maturation, including splenocytes from WT, IL-6(-/-) and TNFalpha transgenic mice. ELISA was used to measure TNFalpha production. IL-6 inhibited osteoclastogenesis in early OCP obtained from wild-type and IL-6(-/-) spleens. Pre-treatment of OCP with M-CSF for three days increased the CD11b(high)/c-Fms+ cell population, resulting in an intermediate staged OCP. Osteoclastogenesis was unaffected by IL-6 in M-CSF pre-treated and TNFalpha transgenic derived OCP. IL-6(-/-) splenocytes secreted greater concentrations of TNFalpha in response to titanium particles than WT; addition of exogenous IL-6 to these cultures decreased TNFalpha expression while anti-IL-6 antibody increased TNFalpha. While IL-6 lacks effects on intermediate staged precursors, the dominant in vivo effects of IL-6 appear to be related to strong suppression of early OCP differentiation and an anti-inflammatory effect targeting TNFalpha. Thus, the absence of IL-6 results in increased inflammatory bone loss.

Elbow medial collateral ligament injuries.

Elbow medial collateral ligament sprain occurs when the elbow is subjected to a valgus force exceeding the tensile properties of the medial collateral ligament (MCL). This is an injury seen more often in throwing athletes. Understanding the differential diagnosis of medial elbow pain is paramount to diagnose MCL injury as well as addressing other medial elbow pathology. A natural evolution regarding MCL injury has occurred over the past 20 years, with modifications of the original surgical procedure, specificity and sensitivity analysis of imaging modalities, and physical exam maneuvers to diagnose MCL pathology. In order for the MCL literature to advance further, more biomechanical and long-term clinical outcome data for the respective surgical modifications are needed. This review describes MCL injury pathophysiology, patient evaluation, reconstruction indications/contraindications, and current and evolving surgical techniques.