Rod fracture in adult spinal deformity surgery fused to the sacrum: prevalence, risk factors, and impact on health-related quality of life in 526 patients.

BACKGROUND CONTEXT: Risk factors associated with rod fracture (RF) following adult spinal deformity (ASD) surgery fused to the sacrum remain debatable, and the impact of RF on patient-reported outcomes (PROs) after ASD surgery has not been investigated. PURPOSE: We aimed to evaluate the prevalence of and risk factors for RF and determine PROs changes associated with RF after ASD surgery fused to the sacrum. STUDY DESIGN/SETTING: A retrospective single-center cohort study was performed. PATIENT SAMPLE: Patients undergoing long-construct posterior spinal fusions to the sacrum performed at a single institution by two senior spine surgeons from 2004 to 2014 were included. OUTCOME MEASURES: Patient demographics, radiographic parameters, and surgical factors were assessed for risk factors associated with RF. Oswestry Disability Index (ODI) and Scoliosis Research Society-30 (SRS-30) scores were assessed at baseline, 1 year postoperatively, and latest follow-up. METHODS: Inclusion criteria were ASD patients age >18 who had ≥5 vertebrae instrumented and fused posteriorly to the sacrum and either development of RF or no development of RF with minimum 2-year follow-up. Patient characteristics, operative data, radiographic parameters, and PROs were analyzed at baseline and follow-up. Separate Cox proportional hazard models based on rod material and diameter were used to determine factors associated with RF. RESULTS: Five hundred twenty-six patients (80%) were available for analysis. RF occurred in 97 (18.4%) patients (unilateral RF n=61 [63%]; bilateral RF n=36 [37%]). Risk factors for fracture of 5.5 mm cobalt chromium (CC) instrumentation (CC 5.5 model) included preoperative sagittal vertical axis (hazard ratio [HR] 1.07, 95% confidence interval [95% CI] 1.02-1.14 per 1-cm increase), preoperative thoracolumbar kyphosis (HR 1.02, 95% CI 1.01-1.04 per 1-degree increase), and number of levels fused for patients who received rhBMP-2 <12 mg per level fused (HR 1.48, 95% CI 1.20-1.82 per 1-level increase). Implants that were 5.5-mm CC constructs were at a higher risk for fracture than 6.35-mm stainless steel (SS) constructs (HR 8.49, 95% CI 4.26-16.89). The RF group had less overall improvement in SRS Satisfaction (0.93 vs. 1.32; p=.007) and SRS Self-image domain scores (0.72 vs. 1.02; p=.01). The bilateral RF group had less overall improvement in ODI (8.1 vs. 15.8; p=.02), SRS Subscore (0.51 vs. 0.85; p=.03), and SRS Pain domain scores (0.48 vs. 0.95; p=.02) compared with the non-RF group at final follow-up. CONCLUSIONS: The prevalence of all RF after index procedures was 18.4%, 37% for bilateral RF. Greater preoperative sagittal vertical axis, greater preoperative thoracolumbar kyphosis, increased number of vertebrae fused for patients who received rhBMP-2 <12 mg per level fused, and CC 5.5-mm rod were associated with RF. Less improvement in patient satisfaction and self-image was noted in the RF group. Furthermore, bilateral RF significantly affected PROs as measured by ODI and SRS Subscore at final follow-up.

Development of the philometrids Philometra overstreeti and philometroides paralichthydis in the experimentally infected copepod Oithona colcarva.

Philometra overstreeti Moravec et de Buron, 2006 and Philomnetroides paralichthydis Moravec et de Buron, 2006 are common parasites of the southern flounder, Paralichthys lethostigma Jordan et Gilbert. Because the life cycles of these parasites are unknown, our goal was to assess whether species of copepod commonly found in our estuaries could serve as intermediate hosts for these philometrids. Individuals of five species of copepods were collected and exposed to L1 larvae of each philometrid species. The cyclopoid Oithlona colcarva Bowman was the only species to become successfully infected. Successive moulting of philometrid larvae in the haemocoel of the copepods was studied using transmission electron microscopy. At 23 degrees C the moult from L1 to L2 was observed for both species as early as 24 h post exposure to L1 larvae. The moult from L2 to L3 was initiated within 2 days post exposure and completed by 6-7 days post exposure. Some parasite-induced tissue damage occurred in the copepod but no cellular response against larval philometrids was observed.