Water quality trends of streams in Puerto Rico: Evaluating 50 years of the Clean Water Act.

Water quality regulations entail a substantial commitment of resources from governments and private entities. It is important to continually evaluate the effectiveness of these regulations to ensure they are having the intended impact. In this paper, we evaluated nutrient data as indicators of primary productivity and dissolved oxygen (DO) concentrations and pH as response variables to assess historical water quality trends from 55 stations of Puerto Rico. The stations were divided into impaired versus non-impaired categories based on their historical total phosphorus (TP) mean concentration. Mean TP and total nitrogen (TN) concentrations were significantly higher in the impaired stations relative to the non-impaired stations. In contrast, DO mean concentrations and mean pH values were significantly lower in the impaired stations. A generalized additive mixed model was used to demonstrate temporal trends. A significant decrease in TP and TN concentrations was observed with time at the impaired stations. This was accompanied by significant increases in DO concentrations and pH. The non-impaired stations showed a marginal (statistically nonsignificant) decreasing trend with time. The large reductions in nutrient concentrations observed at the impaired stations seem to be related to the closure of several primary wastewater treatment plants (WWTPs) across the island. The conversion of abandoned crop agricultural lands into secondary forest in recent decades has resulted in small but significant decreases in TN (not TP) in receiving streams. We conclude that the Clean Water Act has promoted improvements in water quality in Puerto Rico by advancing upgrades in sanitary infrastructure and the regulation of point sources of pollution.

Structural Allograft Versus Mechanical Interbody Devices Augmented With Osteobiologics in Anterior Cervical Discectomy and Fusion: A Systematic Review.

STUDY DESIGN: Systematic Literature Review. OBJECTIVE: Perform a systematic review evaluating postoperative fusion rates for anterior cervical discectomy and fusion (ACDF) using structural allograft vs various interbody devices augmented with different osteobiologic materials. METHODS: Comprehensive literature search using PubMed, Embase, The Cochrane Library, and Web of Science was performed. Included studies were those that reported results of 1-4 levels ACDF using pure structural allograft compared with a mechanical interbody device augmented with an osteobiologic. Excluded studies were those that reported on ACDF with cervical corpectomy; anterior and posterior cervical fusions; circumferential (360° or 540°) fusion or revision ACDF for nonunion or other conditions. Risk of bias was determined using the Cochrane review guidelines. RESULTS: 8 articles reporting fusion rates of structural allograft and an interbody device/osteobiologic pair were included. All included studies compared fusion rates following ACDF among structural allograft vs non-allograft interbody device/osteobiologic pairs. Fusion rates were reported between 84% and 100% for structural allograft, while fusion rates for various interbody device/osteobiologic combinations ranged from 26% to 100%. Among non-allograft cage groups fusion rates varied from 73-100%. One study found PEEK cages filled with combinations of autograft, allograft, and demineralized bone matrix (DBM) to have an overall fusion rate of 26%. In one study comparing plate and zero-profile constructs, there was no difference in fusion rates for two-level fusions. CONCLUSION: There was limited data comparing fusion outcomes of patients undergoing ACDF using structural allograft vs interbody devices augmented with osteobiologic materials to support superiority of one method.

Associated factors of patients with spinal stenosis who undergo reoperation after a posterior lumbar spinal fusion in a Hispanic-American population.

PURPOSE: The aim of this study was to evaluate the associated factors of patients with LSS who undergo reoperation after a PLSF in a Hispanic-American population. METHODS: A retrospective single-center review was performed from all non-age-related Hispanic-Americans with LSS who underwent one or two-level PLSF from 2008 to 2018. Baseline characteristics were analyzed between the reoperation and no-reoperation group using a bivariate and multivariate analyses. RESULTS: Out of 425 patients who underwent PLSF, 38 patients underwent reoperation. At a two-year follow-up, the reoperation rate was 6.1% (26/425), mostly due to pseudoarthrosis (39.5%), recurrent stenosis (26.3%), new condition (15.8%), infection (10.5%), hematoma (5.3%), and dural tear (2.6%). Patients who underwent reoperation were more likely to have a preoperative history of epidural steroid injection (ESI) (OR 5.18, P = 0.009), four or more comorbidities (OR 2.69, P = 0.028), and operated only with a posterolateral fusion without intervertebral fusion (OR 2.15, P = 0.032). Finally, the multivariable analysis showed that ESI was the only independent associated factor in patients who underwent reoperation after a PLSF in our group. CONCLUSION: Among this population who underwent surgery, a reoperation rate at two years of follow-up was less than ten percent. Our study did not find any associated factor inherent to Hispanic-Americans, as ethnic group, who were reoperated after LSS.