RESUMEN
PURPOSE: To compare the rate of previous knee arthroscopy in patients undergoing total knee arthroplasty (TKA) before (2005-2006) and after (2018) publication of landmark studies that examined the effectiveness of knee arthroscopy as well as the American Academy of Orthopaedic Surgeons 2013 knee arthroscopy guidelines. METHODS: We performed a retrospective chart review of 214 patients who underwent a TKA between 2005 and 2006 (Group 1) and 213 patients who underwent a TKA in 2018 (Group 2). We reviewed medical records to determine whether previous knee arthroscopy was performed. Group comparisons were made using the t test for continuous data and the χ2 test for categorical data, and means ± standard deviation are presented. RESULTS: Patients in Group 2 were older than those in Group 1 (67.0 ± 8.3 vs 64.3 ± 11.5 years, P = .01); however, there were no differences between groups with respect to sex (P = .40), body mass index (P = .36), and laterality of TKA (P = .05). There was no difference in the history of previous knee arthroscopy between Groups 1 and 2 overall (27% vs 32%, P = .27) and within 10 years of TKA (17% vs 15%, P = .44). CONCLUSIONS: We did not find a difference in the number of previous knee arthroscopies for patients undergoing TKA in 2018 versus 2005-2006. This suggests that the recommendations set forth by landmark clinical trials that examined the effectiveness of knee arthroscopy and the AAOS 2013 knee arthroscopy guidelines did not have a sudden impact within our geographic region, but there is some evidence to suggest a gradual shift in treatment, where knee arthroscopy is withheld near imminent knee arthroplasty. LEVEL OF EVIDENCE: III, retrospective comparative study.
RESUMEN
Struvite (MgNH4PO4·6H2O) forms in aqueous systems with high ammonia and phosphate concentrations. However, conditions that result into struvite formation are highly dependent on the ionic compositions, temperature, pH, and ion speciation characteristics. The primary ions involved in struvite formation have complex interactions and can form different crystals depending on the ionic levels, pH and temperature. Struvite as well as struvite analogues (with substitution of monovalent cations for NH4+ or divalent cations for Mg2+) as well as other crystals can form simultaneously and result in changes in crystal morphology during crystal growth. This review provides the results from experimental and theoretical studies on struvite formation and decomposition studies. Characteristics of NH4+ or divalent cations for Mg2+ were evaluated in comparison to monovalent and divalent ions for formation of struvite and its analogues. Struvite crystals forming in wastewater systems are likely to contain crystals other than struvite due to ionic interactions, pH changes, temperature effects and clustering of ions during nucleation and crystal growth. Decomposition of struvite occurs following a series of reactions depending on the rate of heating, temperature and availability of water during heating.