Ossification of the posterior longitudinal ligament (OPLL) is a rare pathologic process of lamellar bone deposition that can result in spinal cord compression. While multiple genetic and environmental factors have been related to the development of OPLL, the pathophysiology remains poorly understood. Asymptomatic patients may be managed conservatively and patients with radiculopathy or myelopathy should be considered for surgical decompression. Multiple studies have demonstrated the morphology and size of the OPLL as well as the cervical alignment have significant implications for the appropriate surgical approach and technique. In this review, we aim to address all the available literature on the etiology, history, presentation, and management of OPLL in an effort to better understand OPLL and give our recommendations for the treatment of patients presenting with OPLL.

Background: Lumbar isthmic spondylolisthesis (IS) in adults is defined as the forward slippage of a vertebra onto the top of the vertebra, resulting from a defect in the pars intraarticular, and can be low grade or high grade. Persistent back pain or neurological deficit are indications for surgical intervention. Surgery can be done from back, front, or both, with or without fusion, instrumentation, or decompression, and short or long segment. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, several databases were searched through August 2017 for any observational or experimental studies that evaluated combined anterior-posterior approach versus posterior alone in management of IS. Primary outcome was fusion rate, whereas secondary outcomes included functional outcomes (Visual Analogue Scale [VAS] and Oswestry Disability Index [ODI] score), complication rate (infection, neurological), and reoperation rate. Descriptive, quantitative, and qualitative data were extracted. Most of the cases were low-grade IS. Results: Of the 645 articles identified, 6 studies were eligible for the meta-analysis, with a total of 397 patients with IS, 198 in the combined (anterior interbody fusion [ALIF] þ postero-lateral fusion [PLF]) group and 199 in the posterior (transformational interbody fusion [TLIF]/ postero-lateral interbody fusion [PLIF] þ PLF) group, average age of 47.2 years, and 185:212 male : female ratio. Although the fusion rate reached 100% in some studies, the pooled odds ratio (OR) of fusion rate (OR ¼ 1.02, 95% confidence interval [CI]: 0.294, 3.552, P ¼ .972) did not reach statistical significance between (ALIF þ PLF) versus (TLIF/PLIF þ PLF). The estimated pooled standardized mean difference (SMD) showed less blood loss in the anterior approach compared to the posterior approach (SMD ¼À0.528, 95% CI: À0.777, À0.278, P , .001), with no difference in operative time and length of hospital stay. Despite both groups showing significant improvement in pain and functional scores at final follow up, ODI and VAS were not significantly different between groups with ODI (SMD ¼À0.644, 95% CI: À1.948, 0.621, P ¼ .311) and VAS (SMD ¼ 0.113, 95% CI: À0.173, 0.400, P ¼ .439). The complication rate for the anterior approach was higher than the posterior, whereas reoperation rate was higher in the posterior approach than the anterior. Conclusions: No significant difference between anterior and posterior approaches was found in the global assessment of fusion rate and clinical outcomes, despite a higher rate of complications using the anterior approach. Level of Evidence: 3. Clinical Relevance: Both anterior and posterior approach are a valid option for treatment of isthemic spondylolisthesis Lumbar Spine

Current data suggests that, of the two treatments, MSC provides more significant disease modifying effect; however, further research needs to be done to compare these two treatments and determine if there is a synergetic effect when combined.