Faculty Bibliography

BACKGROUND:There are many risk factors for arthrofibrosis and manipulation under anesthesia (MUA) following total knee arthroplasty (TKA). However, no study has elucidated whether a history of MUA increases the risk of contralateral MUA in patients undergoing staged bilateral TKA. METHODS:A retrospective review of an institutional database of TKAs was performed. All patients aged ≥18 years who underwent primary staged bilateral TKAs were screened for inclusion. Staged bilateral TKAs were viewed as 2 distinct events based on the temporal order in which they occurred: TKA#1 (occurred first) and TKA#2 (occurred second). Following TKA#1, patients were split into 2 groups: those who underwent MUA (Group MANIP) and those who did not (Group NO MANIP). The subsequent risk of undergoing MUA following TKA#2 was then assessed and compared between the 2 groups. Chi-squared tests were used for comparison. RESULTS:A total of 5,330 patients who underwent primary uncomplicated staged bilateral TKAs (10,660 knees) during the study period were identified. Overall, 2.1% of patients underwent MUA following TKA#1 and 1.9% of patients underwent MUA following TKA#2. In the MANIP group, 21.4% of patients underwent MUA following TKA#2, while only 1.5% underwent MUA in the NO MANIP group. This 14.3-fold increase in the risk of MUA in the MANIP group following TKA#2 was statistically significant (21.4% vs 1.5%, absolute risk reduction = 19.9%, relative risk reduction = 93.0%, P < .0001). CONCLUSION:Patients who undergo MUA during the first TKA of a staged bilateral TKA are 14.3 times more likely to undergo a subsequent MUA than those who did not undergo MUA following their first TKA.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:To evaluate the impact of incidental durotomy during spine surgery on the development of delirium in patients aged 65 and older. SUMMARY OF BACKGROUND DATA/BACKGROUND:Delirium after spine surgery has been shown to increase the risk of adverse events, including morbidity and readmissions. Durotomy has previously been postulated to influence the risk of delirium, but this has not been explored in patients 65 and older, the demographic at greatest risk of developing delirium. METHODS:We obtained clinical data on 766 patients, including 182 with incidental durotomy, from the Partners healthcare registry (2012-2019). Patients had their medical records abstracted and age, biologic sex, body mass index, smoking status, preoperative diagnosis, use of a fusion-based procedure, and number of comorbidities were recorded. Our primary outcome was the development of delirium. Our primary predictor was incidental durotomy. We used logistic regression techniques to adjust for sociodemographic and clinical confounders. We performed propensity score matching as a sensitivity test. We hypothesized that elderly patients would be at increased risk of delirium following durotomy. RESULTS:Delirium was identified in 142 patients (19%). Among patients with an incidental durotomy, 26% were diagnosed with delirium. The incidence of delirium was 16% in the control group. Following adjusted analysis, the likelihood of delirium was significantly greater in patients with a durotomy (odds ratio [OR] 1.91; 95% confidence interval [CI] 1.27, 2.88). After propensity score matching, durotomy remained significantly associated with delirium in multivariable adjusted analyses (OR 1.90; 95% CI 1.07, 3.39). CONCLUSION/CONCLUSIONS:This investigation is among the first to specifically evaluate an association between durotomy and delirium in elderly patients undergoing spine surgery. The increased association between durotomy and delirium in this cohort should prompt increased surveillance and interventions designed to minimize the potential for cognitive deterioration or impairment during postoperative management of a durotomy. LEVEL OF EVIDENCE/METHODS:3.

BACKGROUND:Incidental durotomy is a common intraoperative complication during spine surgery with potential implications for postoperative recovery, patient-reported outcomes, length of stay, and costs. To our knowledge, there are no processes available for automated surveillance of incidental durotomy. PURPOSE:The purpose of this study was to develop natural language processing (NLP) algorithms for automated detection of incidental durotomies in free-text operative notes of patients undergoing lumbar spine surgery. PATIENT SAMPLE:Adult patients 18 years or older undergoing lumbar spine surgery between January 1, 2000 and June 31, 2018 at two academic and three community medical centers. OUTCOME MEASURES:The primary outcome was defined as intraoperative durotomy recorded in free-text operative notes. METHODS:An 80:20 stratified split was undertaken to create training and testing populations. An extreme gradient-boosting NLP algorithm was developed to detect incidental durotomy. Discrimination was assessed via area under receiver-operating curve (AUC-ROC), precision-recall curve, and Brier score. Performance of this algorithm was compared with current procedural terminology (CPT) and international classification of diseases (ICD) codes for durotomy. RESULTS:Overall, 1,000 patients were included in the study and 93 (9.3%) had a recorded incidental durotomy in the free-text operative report. In the independent testing set (n=200) not used for model development, the NLP algorithm achieved AUC-ROC of 0.99 for detection of durotomy. In comparison, the CPT/ICD codes had AUC-ROC of 0.64. In the testing set, the NLP algorithm detected 16 of 18 patients with incidental durotomy (sensitivity 0.89) whereas the CPT and ICD codes detected 5 of 18 (sensitivity 0.28). At a threshold of 0.05, the NLP algorithm had specificity of 0.99, positive predictive value of 0.89, and negative predictive value of 0.99. CONCLUSIONS:Internal validation of the NLP algorithm developed in this study indicates promising results for future NLP applications in spine surgery. Pending external validation, the NLP algorithm developed in this study may be used by entities including national spine registries or hospital quality and safety departments to automate tracking of incidental durotomies.

BACKGROUND:While there is emerging literature describing the use of narcotics for post-operative pain control following TKA, little data is available regarding narcotic use in partial knee replacements. The aim of this study is to compare the early post-operative narcotic requirements after medial compartmental arthroplasty (UKA) and patellofemoral arthroplasty (PFA) with that of TKA. METHODS:In this retrospective chart review, we identified 37 patients who underwent PFA and 71 patients who underwent UKA. We identified a cohort of TKA patients who were matched to the unicompartmental group based on sex and age (n = 108). The primary outcome measure was self-reported use of opioids for pain management at the first post-operative clinic visit. Opioid use between groups was compared using Chi-square analysis. RESULTS:The PFA group was younger (p < 0.001) and consisted of more females (p < 0.001) than the UKA group. The UKA cohort had more non-smoking patients (p = 0.044) compared to the PFA cohort. Self-reported opioid use at the first post-operative visit differed between the three groups of patients (p < 0.001). A greater proportion of both PFA (38% vs. 11%; p < 0.001) and TKA (41% vs. 11%; p = 0.01) patients reported opioid use when compared to UKA patients. No differences in opioid use existed between TKA and PFA groups (p = 0.61). CONCLUSION/CONCLUSIONS:The prevalence of PFA patients who report opioid use at the first post-operative visit is similar to that for patients following TKA, suggesting that pain management protocols for this specific subset of partial knee arthroplasty patients should be structured similar to TKA patients and separate from UKA patients.

STUDY DESIGN:Retrospective cohort study. OBJECTIVE:To assess whether administration of prophylactic vancomycin, in addition to cefazolin decreased revision surgeries for postoperative infection (SSI) as well as the need for revisions overall. SUMMARY OF BACKGROUND DATA:In 2010 our institution implemented an antibiotic prophylaxis regimen consisting of intravenous vancomycin and cefazolin that applied to all patients receiving surgical implants. The impact of this change in prophylactic antibiotic regimen on SSIs following instrumented spinal fusions remains unknown. METHODS:We conducted a prepost analysis evaluating the effect of the change in antibiotic prophylaxis on SSIs following instrumented spinal fusions. We collected data on all eligible patients over the course of 2005 to 2009 and 2011 to 2015. We used logistic regression techniques to evaluate unadjusted results for the prophylactic antibiotic protocol on all revision surgeries, as well as those for SSI, followed by sequential adjustments for sociodemographic factors and surgical characteristics. RESULTS:Revision surgeries performed for a diagnosis of infection were reduced from a rate of 4% (n = 57) in the period 2005 to 2009 to 2% (n = 44) over 2011 to 2015 (P < 0.001). At the same time, the incidence of revision surgeries for any cause was also reduced (14% in 2005-2009 vs. 9% in 2011-2015; P < 0.001). In adjusted analysis, the odds of a revision procedure for SSI were reduced by 50% following introduction of the protocol (OR 0.50; 95% CI 0.33, 0.76). No significant difference in the organisms responsible for SSI was identified between 2005 and 2009 and 2011 and 2015 (P = 0.22). CONCLUSION:This natural experiment has shown some utility for a preoperative prophylactic antibiotic regimen of vancomycin and cefazolin, including meaningful reductions in revision procedures performed for SSI. This is the first effort we are aware of to consider a uniform institutional protocol that employs the use of intravenous vancomycin and cefazolin as prophylactic agents. LEVEL OF EVIDENCE:2.

BACKGROUND:The aim of the present study was to evaluate the influence of organism type on the performance of the synovial fluid C-reactive protein (CRP) test. METHODS:We retrospectively reviewed the results of 21,422 synovial fluid samples sent to one common laboratory for the purpose of diagnostic testing for periprosthetic joint infection. Both a synovial fluid CRP result and a positive culture were present for 1789 submitted samples. The cultured organisms were grouped by species, virulence, and gram type; and the median CRP level was determined for each group. RESULTS:The median synovial fluid CRP level was significantly lower for less-virulent organisms, when compared to those organisms classified as virulent (15.10 mg/L vs 32.70 mg/L; P < .0001). Some less-virulent species such as yeast and Staphylococcus epidermidis were associated with a 4-10 times lower CRP response than those of virulent organisms such as Streptococcus agalactiae and Staphylococcus aureus (P < .0001). Bacterial gram type had no influence on the median CRP result. The rate of false-negative CRP values was 50.9% for yeast, 29.4% for S. epidermidis, 28.5% for all less-virulent organisms, and 11.6% for all virulent organisms. CONCLUSION:The CRP response appears to be highly dependent on the infecting organism and is more likely to provide false-negative results in the setting of less-virulent organisms. Although the use of a CRP level is an important part of the workup for periprosthetic joint infection, surgeons must be aware that this protein may yield a false-negative result in the setting of less-virulent organisms.

Orthopedic surgical interns must gain a broad array of clinical skills in a short time. However, recent changes in health care have limited resident-patient exposures. With the reported success of simulation training in the surgical literature, the American Board of Orthopaedic Surgery (ABOS) and Residency Review Committee for Orthopaedic Surgery have required that surgical simulation training be a component of the intern curricula in orthopedic surgical residencies. This study examined the short-term effectiveness of an orthopedic "intern boot camp" covering 7 of 17 simulation training concept modules published by the ABOS. Eight orthopedic post-graduate year 1 (PGY-1) residents (study group) completed a structured 3-month curriculum and were compared with 7 post-graduate year 2 (PGY-2) residents (comparison group) who had just completed their orthopedic surgical internship. Seven core skills were assessed using both task-specific and global rating scales. The PGY-1 residents demonstrated a statistically significant improvement in all 7 modules with respect to their task-specific pre-test scores: sterile technique (P=.001), wound closure (P<.001), knot tying (P=.017), casting and splinting (P<.001), arthrocentesis (P=.01), basics of internal fixation (P<.001), and compartment syndrome evaluation (P=.004). After the camp, PGY-1 and -2 scores in task-specific measures were not significantly different. A 3-month simulation-based boot camp instituted early in orthopedic internship elevated a variety of clinical skills to levels exhibited by PGY-2 residents.

OBJECT/OBJECTIVE:It is unclear if there is a relationship between Chiari malformation Type I (CM-I) and body mass index (BMI). The aim of this study was to identify the relationship between BMI and cerebellar tonsil position in a random sample of people. METHODS:Cerebellar tonsil position in 2400 subjects from a cohort of patients undergoing MRI was measured. Three hundred patients were randomly selected from each of 8 age groups (from 0 to 80 years). A subject was then excluded if he or she had a posterior fossa mass or previous posterior fossa decompression or if height and weight information within 1 year of MRI was not recorded in the electronic medical record. RESULTS:There were 1310 subjects (54.6%) with BMI records from within 1 year of the measured scan. Of these subjects, 534 (40.8%) were male and 776 (59.2%) were female. The average BMI of the group was 26.4 kg/m(2), and the average tonsil position was 0.87 mm above the level of the foramen magnum. There were 46 subjects (3.5%) with a tonsil position ≥ 5 mm below the level of the foramen magnum. In the group as a whole, there was no correlation (R(2) = 0.004) between BMI and cerebellar tonsil position. CONCLUSIONS:In this examination of 1310 subjects undergoing MRI for any reason, there was no relationship between BMI and the level of the cerebellar tonsils or the diagnosis of CM-I on imaging.