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  • Author or Editor: Merritt D. Kinon x
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Postoperative urinary retention in patients undergoing elective spinal surgery

David Altschul, Andrew Kobets, Jonathan Nakhla, Ajit Jada, Rani Nasser, Merritt D. Kinon, Reza Yassari, and John Houten

OBJECTIVE

Postoperative urinary retention (POUR) is a common problem leading to morbidity and an increased hospital stay. There are limited data regarding its baseline incidence in patients undergoing spinal surgery and the risk factors with which it may be associated. The purpose of this study was to evaluate the incidence of POUR in elective spine surgery patients and determine the factors associated with its occurrence.

METHODS

The authors retrospectively reviewed the records of patients who had undergone elective spine surgery and had been prospectively monitored for POUR during an 18-month period. Collected data included operative positioning, surgery duration, volume of intraoperative fluid, length of hospital stay, and patient characteristics such as age, sex, and medical comorbidities. Dialysis patients or those with complete urinary retention preoperatively were excluded from analysis.

RESULTS

Of the 397 patients meeting the study inclusion criteria, 35 (8.8%) developed POUR. An increased incidence of POUR was noted in those who underwent posterior lumbar surgery, those with benign prostatic hypertrophy (BPH), those with chronic constipation or prior urinary retention, and those using a patient-controlled analgesia pump postoperatively. An increased incidence of POUR was seen with a longer operative time but not with intraoperative intravenous fluid administration. A significant relationship between the female sex and POUR was noted after controlling for BPH, yet there was no association between POUR and diabetes or intraoperative instrumentation. Postoperative retention significantly prolonged the hospital stay. Three patients developed epidural hematomas necessitating operative reexploration, and while they experienced POUR, they also developed the full constellation of cauda equina syndrome.

CONCLUSIONS

Awareness of the risk factors for POUR may be useful in perioperative Foley catheter management and in identifying patients who need particular vigilance when they are due to void postprocedure. A greater understanding of POUR may also prevent longer hospital stays in select at-risk patients. Postoperative retention is rarely caused by a postoperative cauda equina syndrome due to epidural hematoma, which is also associated with saddle anesthesia, leg pain, and weakness, yet the delineation of isolated POUR from this urgent complication is necessary for optimal patient care.

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Selecting the lowest instrumented vertebra in a multilevel posterior cervical fusion across the cervicothoracic junction: a biomechanical investigation

Yaroslav Gelfand, Daniel Franco, Merritt D. Kinon, Rafael De la Garza Ramos, Reza Yassari, Jonathan A. Harris, Samantha Flamand, Joshua P. McGuckin, Jorge L. Gonzalez, Jonathan M. Mahoney, and Brandon S. Bucklen

OBJECTIVE

Posterior cervical fusion is a common surgical treatment for patients with myeloradiculopathy or regional deformity. Several studies have found increased stresses at the cervicothoracic junction (CTJ) and significantly higher revision surgery rates in multilevel cervical constructs that terminate at C7. The purpose of this study was to investigate the biomechanical effects of selecting C7 versus T1 versus T2 as the lowest instrumented vertebra (LIV) in multisegmental posterior cervicothoracic fusion procedures.

METHODS

Seven fresh-frozen cadaveric cervicothoracic spines (C2–L1) with ribs intact were tested. After analysis of the intact specimens, posterior rods and lateral mass screws were sequentially added to create the following constructs: C3–7 fixation, C3–T1 fixation, and C3–T2 fixation. In vitro flexibility tests were performed to determine the range of motion (ROM) of each group in flexion-extension (FE), lateral bending (LB), and axial rotation (AR), and to measure intradiscal pressure of the distal adjacent level (DAL).

RESULTS

In FE, selecting C7 as the LIV instead of crossing the CTJ resulted in the greatest increase in ROM (2.54°) and pressure (29.57 pound-force per square inch [psi]) at the DAL in the construct relative to the intact specimen. In LB, selecting T1 as the LIV resulted in the greatest increase in motion (0.78°) and the lowest increase in pressure (3.51 psi) at the DAL relative to intact spines. In AR, selecting T2 as the LIV resulted in the greatest increase in motion (0.20°) at the DAL, while selecting T1 as the LIV resulted in the greatest increase in pressure (8.28 psi) in constructs relative to intact specimens. Although these trends did not reach statistical significance, the observed differences were most apparent in FE, where crossing the CTJ resulted in less motion and lower intradiscal pressures at the DAL.

CONCLUSIONS

The present biomechanical cadaveric study demonstrated that a cervical posterior fixation construct with its LIV crossing the CTJ produces less stress in its distal adjacent discs compared with constructs with C7 as the LIV. Future clinical testing is necessary to determine the impact of this finding on patient outcomes.

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Superior discrimination of the Risk Analysis Index compared with the 5-item modified frailty index in 30-day outcome prediction after anterior cervical discectomy and fusion

Christian A. Bowers, Samantha Varela, Alexandria F. Naftchi, Syed Faraz Kazim, Daniel E. Hall, Christina Ng, Cameron Rawanduzy, Eris Spirollari, Sima Vazquez, Ankita Das, Gillian Graifman, Derek B. Asserson, Jose F. Dominguez, Merritt D. Kinon, and Meic H. Schmidt

OBJECTIVE

The objective of this paper was to compare the predictive ability of the recalibrated Risk Analysis Index (RAI-rev) with the 5-item modified frailty index-5 (mFI-5) for postoperative outcomes of anterior cervical discectomy and fusion (ACDF).

METHODS

This study was performed using data of adult (age > 18 years) ACDF patients obtained from the National Surgical Quality Improvement Program database during the years 2015–2019. Multivariate modeling and receiver operating characteristic (ROC) curve analysis, including area under the curve/C-statistic calculation with the DeLong test, were performed to evaluate the comparative discriminative ability of the RAI-rev and mFI-5 for 5 postoperative outcomes.

RESULTS

Both the RAI-rev and mFI-5 were independent predictors of increased postoperative mortality and morbidity in a cohort of 61,441 ACDF patients. In the ROC analysis for 30-day mortality prediction, C-statistics indicated a significantly better performance of the RAI-rev (C-statistic = 0.855, 95% CI 0.852–0.858) compared with the mFI-5 (C-statistic = 0.684, 95% CI 0.680–0.688) (p < 0.001, DeLong test). The results were similar for postoperative ACDF morbidity, Clavien-Dindo grade IV complications, nonhome discharge, and reoperation, demonstrating the superior discriminative ability of the RAI-rev compared with the mFI-5.

CONCLUSIONS

The RAI-rev demonstrates superior discrimination to the mFI-5 in predicting postoperative ACDF mortality and morbidity. To the authors’ knowledge, this is the first study to document frailty as an independent risk factor for postoperative mortality after ACDF. The RAI-rev has conceptual fidelity to the frailty phenotype and may be more useful than the mFI-5 in preoperative ACDF risk stratification. Prospective validation of these findings is necessary, but patients with high RAI-rev scores may benefit from knowing that they might have an increased surgical risk for ACDF morbidity and mortality.