Faculty Bibliography

OBJECTIVE: Evidence-based decision-making tools are widely used to guide cervical spine assessment in adult trauma patients. Similar tools validated for use in injured children are lacking. A paediatric-specific approach is appropriate given important differences in cervical spine anatomy, mechanism of spinal injury and concerns over ionising radiation in children. The present study aims to survey physicians' knowledge and application of cervical spine assessment in injured children. METHODS: A cross-sectional survey of physicians actively engaged in trauma care within a paediatric trauma centre was undertaken. Participation was voluntary and responses de-idenitified. The survey comprised 20 questions regarding initial assessment, imaging, immobilisation and perioperative management. Physicians' responses were compared with available current evidence. RESULTS: Sixty-seven physicians (28% registrars, 17% fellows and 55.2% consultants) participated. Physicians rated altered mental state, intoxication and distracting injury as the most important contraindications to cervical spine clearance in children. Fifty-four per cent considered adequate plain imaging to be 3-view cervical spine radiographs (anterior-posterior, lateral and odontoid), whereas 30% considered CT the most sensitive modality for detecting unstable cervical spine injuries. Physicians' responses reflected marked heterogeneity regarding semi-rigid cervical collars and what constitutes cervical spine 'clearance'. Greater consensus existed for perioperative precautions in this setting. CONCLUSIONS: Physicians actively engaged in paediatric trauma care demonstrate marked heterogeneity in their knowledge and application of cervical spine assessment. This is compounded by a lack of paediatric-specific evidence and definitions, involvement of multiple specialties and staff turnover within busy departments. A validated decision-making tool for cervical spine assessment will represent an important advance in paediatric trauma.

Introduction/objectives: Spinal deformity has a known deleterious effect upon the outcomes of THA and acetabular component positioning. This study sought to evaluate the relationship between severity of spinal deformity parameters and acetabular cup position, rate of dislocation, and rate of revision among patients with THAs and concomitant spinal deformity. Methods: A prospectively database of patients with spinal deformity was reviewed and patients with THA were identified. The full standing stereoradiographic images (EOS) were reviewed. Spinal deformity parameters and acetabular cup anteversion and inclination were measured. A chart review was performed to determine dislocation and revision arthroplasty events. Statistical analysis was performed to determine correlation of deformity with acetabular cup position. Subgroup analysis was performed for spinal fusion, dislocation events, and revision THA. Results: 142 patients were identified with THA and spinal deformity, with 152 hips. The rate of dislocation was 5.7%, with a revision rate of 3.6% for instability. Only 42.1% met the radiographic "safe zone" criteria. 7 (77.8%) of the 9 dislocations occurred in patients with acetabular cups outside the safe zone (p = 0.304). Patients with dislocations had significantly higher inclination than those patients who did not dislocate (p = 0.016), but had no difference in anteversion (p = 0.646). Conclusions: In this cohort, patients with THA and concomitant spinal deformity have a high dislocation rate and a high percentage of acetabular cups which lie outside the safe zone in the standing position. Known spinal deformity parameters and the presence of spinal fusion do not correlate strongly with cup position or dislocation rates

Introduction/objectives: Adult spinal deformity correction results in changes in acetabular anteversion. Spinopelvic fusion reduces the protective motion of the pelvis between sitting and standing to prevent THA dislocation. Our hypothesis is that spinal deformity correction may result in dislocation of previously stable THA due to changes in acetabular orientation and fixation to the pelvis. Methods: Patients with previously implanted THA were identified from a prospective database of spinal realignment patients if they had a THA in situ prior to spinal surgery. Only patients with at least 6 months postoperative follow-up and visible THA prostheses were included. All postoperative imaging was reviewed. A chart review was performed to determine the indication for revision THA. Acetabular orientation and global/regional spinopelvic parameter were measured pre-and post-SSD correction. Results: 42 patients met criteria. 27 of these patients underwent a 3-column osteotomy. Four patients (7.2% of patients-5.7% hips) required revision THA after spinal realignment procedure: all revisions were for recurrent dislocations. All had stable THAs prior to spinal realignment. All acetabular components were within Lewinnek's 'safe zone' after ASD correction. There was no difference between the revised and non-revised group in mean anteversion or inclination. All hips requiring revision were fused to the pelvis as part of their SSD correction. Conclusions: Dislocation of a previously stable THA is a potential complication after ASD correction. Instability may be a result of a combination of change in alignment of the acetabular prosthesis, as well as reduced spinopelvic motion from spinopelvic fusion

Introduction/objectives: Lumbar fusion is known to reduce the variation in pelvic tilt between standing and sitting by reducing flexibility of the lumbar spine. Flexibility of the lumbo-pelvic segment theoretically improves stability of a hip replacement during sitting by increasing anterior clearance and acetabular anteversion, thus preventing prosthetic impingement. The effect of lumbar fusion on stability of THA has not been previously investigated. Methods: Medicare database was searched from 2005 to 2012 for patients who underwent THA and spinal fusion. PearlDiver software was used to query the database by ICD-9 procedural code for primary THA and lumbar spinal fusion. The lumbar fusion and THA patients were then divided into three groups-1-2 levels fused, 3-7 levels, and 8 + levels. THA dislocation rates were searched within each group. Patients undergoing THA but no spinal fusion were used as the control group. Statistical significant difference between groups was tested with chi-squared test, and significance at p<0.05. Results: 2912 patients were identified to have THA after lumbar spinal fusion (2420 1-2 level, 476 3-7 level) and 2-year follow-up. The control group of THA patients with no history of spinal fusion consisted of 839,004 patients. The dislocation rate in the control group was 1.55%. Higher dislocation rates were found in patients with spinal fusion of 1-2 levels (2.73%, p<0.0001), 3-7 levels (4.62%, p<0.0001). Patients with 3-7 levels fused had higher dislocation rates than patients with 1-2 levels fused (p<0.0001). Conclusions: Patients with a previous history of lumbar spinal fusion have significantly higher rates of dislocation of their THA than patients without lumbar spinal fusions, and longer fusion segments also had higher dislocation rates

BACKGROUND CONTEXT: Degenerative lumbar stenosis (DLS) patients have been reported to lean forward in an attempt to provide neural decompression. Spinal alignment in patients with DLS may resemble that of adult spinal deformity (ASD). No previous studies have compared and contrasted the compensatory mechanisms of DLS and ASD patients. PURPOSE: To determine the differences in compensatory mechanisms between DLS and ASD patients with increasing severity of sagittal spino-pelvic malalignment. Contrasting these compensatory mechanisms may help determine at what severity sagittal malalignment represents a clinical sagittal deformity rather than a compensation for neural compression. STUDY DESIGN/SETTING: Retrospective clinical and radiological review PATIENT SAMPLE:: Baseline x-rays in patients without spinal instrumentation, with the clinical radiological and diagnoses of DLS or ASD were assessed for patterns of spino-pelvic compensatory mechanisms. Patients were stratified by sagittal vertical axis (SVA) by the Schwab-SRS classification. OUTCOME MEASURES: Radiographic spino-pelvic parameters were measured in the DLS and ASD groups, including SVA, PI-LL, T1SPi, TPA and PT METHODS: The two diagnosis cohorts were propensity matched for pelvic incidence and age. Each group contained 125 patients. Each group was stratified according to the SRS-Schwab classification. Regional spino-pelvic, lower limb and global alignment parameters were assessed in each group to identify differences in compensatory mechanisms between the two groups with differing degrees of deformity. No funding was provided by any third party in relation to carrying out this study or preparation of the manuscript. RESULTS: With mild to moderate malalignment (SRS-Schwab groups '0', or '+' for pelvic tilt, pelvic incidence-lumbar lordosis mismatch or sagittal vertical axis), DLS patients permit anterior truncal inclination and recruit posterior pelvic shift instead of pelvic tilt to maintain balance, while providing relief of neurological symptoms. ASD patients with mild- moderate deformity recruit pelvic tilt earlier than DLS patients. With moderate- severe malalignment, no significant difference was found in compensatory mechanisms between DLS and ASD patients. CONCLUSIONS: Patients with degenerative lumbar stenosis permit mild-moderate deformity without recruiting compensatory mechanisms of pelvic tilt, reducing truncal inclination and thoracic hypokyphosis in order to achieve neural decompression. However with moderate to severe deformity, their desire for upright posture overrides the desire for neural decompression, evident by the adaptation of compensatory mechanisms similar to that of the adult spinal deformity patients.

PURPOSE: Cervical disc replacement has become an acceptable alternative to anterior cervical fusion for the surgical treatment of cervical spine spondylosis resulting in radiculopathy or myelopathy following anterior discectomy and decompression. This concise overview considers the current state of knowledge regarding the continued debate of the role of cervical disc replacement with an update in light of the latest clinical trial results. METHODS: A literature review was performed identifying clinical trials pertaining to the use of cervical disc replacement compared to cervical discectomy and fusion. Single level disease and two level disease were considered. Outcome data from the major clinical trials was reviewed and salient points identified. RESULTS: With lengthier follow-up data becoming available, the equivalence of CDR in appropriately selected cases is becoming clear. This is chiefly manifested by reduced re-operation rates and reduced incidence of adjacent level disease in those treated with arthroplasty. CONCLUSION: Cervical disc replacement shows emerging equivalence in outcomes compared to the gold standard anterior cervical discectomy and fusion. Further longer term results are anticipated to confirm this trend.

BACKGROUND: Hip osteoarthritis often coexists with adult spinal deformity, an abnormality in which sagittal spinopelvic malalignment is present. Debate exists whether to perform spinal realignment correction or total hip arthroplasty first. Hip extension and pelvic tilt are important compensatory mechanisms in the setting of sagittal spinopelvic malalignment and change after spinal realignment. We performed this study to evaluate the effect that the spinal realignment surgical procedure has on acetabular anteversion. METHODS: This study is a retrospective review of a multicenter, prospective, consecutive database of patients with adult spinal deformity who underwent surgical spinal realignment. Only patients who already had undergone a total hip arthroplasty prior to the spinal realignment procedure were retained for analysis. Patients were excluded if they had insufficient imaging or large-head, metal-on-metal bearings or they had undergone revision total hip arthroplasty in the study period. Acetabular anteversion was calculated via the ellipse method on a standing, posterior-anterior, 90-cm radiograph with a well-centered pelvis. Anteversion was measured preoperatively and at six weeks or three months after the spinal realignment procedure. Spinopelvic parameters measured included pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, T1 pelvic angle, sagittal vertical axis, T1-spinopelvic inclination, and thoracic kyphosis. RESULTS: Forty-one hips (thirty-three patients) were identified. Acetabular anteversion significantly reduced (p < 0.001) after spinal correction by mean change of -4.96 degrees (range, -22.32 degrees to +2.36 degrees ). The change in anteversion correlated with the changes in sagittal pelvic orientation (0.828 for the pelvic tilt, -0.757 for the sacral slope, and -0.691 for the lumbar lordosis) and global spinopelvic alignment (0.579 for the sagittal vertical axis and 0.585 for the T1 pelvic angle). Regression analysis revealed that anteversion decreased by 1 degrees for each of the following spinopelvic parameter changes (p < 0.001): 1.105 degrees for spinopelvic tilt, 1.032 degrees for sacral slope, and 3.163 degrees for lumbar lordosis. CONCLUSIONS: Patients with spinopelvic malalignment had a high prevalence of excessively anteverted acetabular components. Sagittal spinal correction following total hip arthroplasty resulted in reduced acetabular anteversion, which may have implications for stability. Changes in anteversion are most closely related to changes in pelvic tilt in an almost one-to-one ratio. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.