Prediction of 30-Day Mortality Following Revision Total Hip and Knee Arthroplasty: Machine Learning Algorithms Outperform CARDE-B, 5-Item, and 6-Item Modified Frailty Index Risk Scores.

BACKGROUND: Although risk calculators are used to prognosticate postoperative outcomes following revision total hip and knee arthroplasty (total joint arthroplasty [TJA]), machine learning (ML) based predictive tools have emerged as a promising alternative for improved risk stratification. This study aimed to compare the predictive ability of ML models for 30-day mortality following revision TJA to that of traditional risk-assessment indices such as the CARDE-B score (congestive heart failure, albumin (< 3.5 mg/dL), renal failure on dialysis, dependence for daily living, elderly (> 65 years of age), and body mass index (BMI) of < 25 kg/m2), 5-item modified frailty index (5MFI), and 6MFI. METHODS: Adult patients undergoing revision TJA between 2013 and 2020 were selected from the American College of Surgeons National Surgical Quality Improvement Program database and randomly split 80:20 to compose the training and validation cohorts. There were 3 ML models - extreme gradient boosting, random forest, and elastic-net penalized logistic regression (NEPLR) - that were developed and evaluated using discrimination, calibration metrics, and accuracy. The discrimination of CARDE-B, 5MFI, and 6MFI scores was assessed individually and compared to that of ML models. RESULTS: All models were equally accurate (Brier score = 0.005) and demonstrated outstanding discrimination with similar areas under the receiver operating characteristic curve (AUCs, extreme gradient boosting = 0.94, random forest = NEPLR = 0.93). The NEPLR was the best-calibrated model overall (slope = 0.54, intercept = -0.004). The CARDE-B had the highest discrimination among the scores (AUC = 0.89), followed by 6MFI (AUC = 0.80), and 5MFI (AUC = 0.68). Albumin < 3.5 mg/dL and BMI (< 30.15) were the most important predictors of 30-day mortality following revision TJA. CONCLUSIONS: The ML models outperform traditional risk-assessment indices in predicting postoperative 30-day mortality after revision TJA. Our findings highlight the utility of ML for risk stratification in a clinical setting. The identification of hypoalbuminemia and BMI as prognostic markers may allow patient-specific perioperative optimization strategies to improve outcomes following revision TJA.

Do preoperative PROMIS scores independently predict 90-day readmission following primary total knee arthroplasty?

INTRODUCTION: The rising demand for total knee arthroplasty (TKA) is expected to increase the total number of TKA-related readmissions, presenting significant public health and economic burden. With the increasing use of Patient-Reported Outcomes Measurement Information System (PROMIS) scores to inform clinical decision-making, this study aimed to investigate whether preoperative PROMIS scores are predictive of 90-day readmissions following primary TKA. MATERIALS AND METHODS: We retrospectively reviewed a consecutive series of 10,196 patients with preoperative PROMIS scores who underwent primary TKA. Two comparison groups, readmissions (n = 79; 3.6%) and non-readmissions (n = 2091; 96.4%) were established. Univariate and multivariate logistic regression analyses were then performed with readmission as the outcome variable to determine whether preoperative PROMIS scores could predict 90-day readmission. RESULTS: The study cohort consisted of 2170 patients overall. Non-white patients (OR = 3.53, 95% CI [1.16, 10.71], p = 0.026) and patients with cardiovascular or cerebrovascular disease (CVD) (OR = 1.66, 95% CI [1.01, 2.71], p = 0.042) were found to have significantly higher odds of 90-day readmission after TKA. Preoperative PROMIS-PF10a (p = 0.25), PROMIS-GPH (p = 0.38), and PROMIS-GMH (p = 0.07) scores were not significantly associated with 90-day readmission. CONCLUSION: This study demonstrates that preoperative PROMIS scores may not be used to predict 90-day readmission following primary TKA. Non-white patients and patients with CVD are 3.53 and 1.66 times more likely to be readmitted, highlighting existing racial disparities and medical comorbidities contributing to readmission in patients undergoing TKA.

Patient-Reported Outcomes Measurement Information System Physical Function and Global Physical Health Subscale Strongly Correlate and Perform Similarly to the Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form.

BACKGROUND: Arthroplasty surgeons use a variety of patient-reported outcome measures (PROMs) to assess functional well-being, including the Knee Injury and Osteoarthritis Outcome Score (KOOS) Physical Function short form (KOOS-PS), Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Short Form 10a (PROMIS PF SF 10a), and PROMIS Global-10 Physical Health subscale. However, there is a paucity of literature assessing their concurrent validity and performance. METHODS: Between June 2016 and December 2020, patient visits at an arthroplasty clinic for knee concerns were identified. Patients who completed KOOS-PS, PROMIS PF SF 10a, and PROMIS Global-10, including its physical and mental health subscales, at the same visit were identified. Spearman rho (ρ) correlations were calculated and ceiling and floor effects identified. Overall, 5,303 patient encounters were included. RESULTS: Among physical function domains, strong correlation existed between the KOOS-PS and PROMIS PF SF 10a (ρ = 0.76, P < .001), KOOS-PS and PROMIS Global Physical Health (ρ = 0.71, P < .001), and PROMIS PF SF 10a and PROMIS Global Physical Health (ρ = 0.78, P < .001). No physical function-focused PROM had an appreciable floor effect (ie, at or more than 1%). The KOOS-PS had a small but measurable ceiling effect (n = 105 [2.0%]). CONCLUSIONS: All of the examined PROMs are acceptable to measure the functional status of patients with knee pathology, with the PROMIS Global-10 also being able to capture elements of mental health too. The PROMIS Global-10 may be of most value of the PROMs assessed, as the United States Centers for Medicare and Medicaid Services already incorporate the mental health component into new alternative payment models.

Validation and Generalizability of Machine Learning Models for the Prediction of Discharge Disposition Following Revision Total Knee Arthroplasty.

BACKGROUND: Postoperative discharge to facilities account for over 33% of the $ 2.7 billion revision total knee arthroplasty (TKA)-associated annual expenditures and are associated with increased complications when compared to home discharges. Prior studies predicting discharge disposition using advanced machine learning (ML) have been limited due to a lack of generalizability and validation. This study aimed to establish ML model generalizability by externally validating its prediction for nonhome discharge following revision TKA using national and institutional databases. METHODS: The national and institutional cohorts comprised 52,533 and 1,628 patients, respectively, with 20.6 and 19.4% nonhome discharge rates. Five ML models were trained and internally validated (five-fold cross-validation) on a large national dataset. Subsequently, external validation was performed on our institutional dataset. Model performance was assessed using discrimination, calibration, and clinical utility. Global predictor importance plots and local surrogate models were used for interpretation. RESULTS: The strongest predictors of nonhome discharge were patient age, body mass index, and surgical indication. The area under the receiver operating characteristic curve increased from internal to external validation and ranged between 0.77 and 0.79. Artificial neural network was the best predictive model for identifying patients at risk for nonhome discharge (area under the receiver operating characteristic curve = 0.78), and also the most accurate (calibration slope = 0.93, intercept = 0.02, and Brier score = 0.12). CONCLUSION: All five ML models demonstrated good-to-excellent discrimination, calibration, and clinical utility on external validation, with artificial neural network being the best model for predicting discharge disposition following revision TKA. Our findings establish the generalizability of ML models developed using data from a national database. The integration of these predictive models into clinical workflow may assist in optimizing discharge planning, bed management, and cost containment associated with revision TKA.

The utility of machine learning algorithms for the prediction of patient-reported outcome measures following primary hip and knee total joint arthroplasty.

BACKGROUND: Patient-reported outcome measures (PROMs) are increasingly used as quality benchmark in total hip and knee arthroplasty (THA; TKA) due to bundled payment systems that aim to provide a patient-centered, value-based treatment approach. However, there is a paucity of predictive tools for postoperative PROMs. Therefore, this study aimed to develop and validate machine learning models for the prediction of numerous patient-reported outcome measures following primary hip and knee total joint arthroplasty. METHODS: A total of 4526 consecutive patients (2137 THA; 2389 TKA) who underwent primary hip and knee total joint arthroplasty and completed both pre- and postoperative PROM scores was evaluated in this study. The following PROM scores were included for analysis: HOOS-PS, KOOS-PS, Physical Function SF10A, PROMIS SF Physical and PROMIS SF Mental. Patient charts were manually reviewed to identify patient demographics and surgical variables associated with postoperative PROM scores. Four machine learning algorithms were developed to predict postoperative PROMs following hip and knee total joint arthroplasty. Model assessment was performed through discrimination, calibration and decision curve analysis. RESULTS: The factors most significantly associated with the prediction of postoperative PROMs include preoperative PROM scores, Charlson Comorbidity Index, American Society of Anaesthesiology score, insurance status, age, length of hospital stay, body mass index and ethnicity. The four machine learning models all achieved excellent performance across discrimination (AUC > 0.83), calibration and decision curve analysis. CONCLUSION: This study developed machine learning models for the prediction of patient-reported outcome measures at 1-year following primary hip and knee total joint arthroplasty. The study findings show excellent performance on discrimination, calibration and decision curve analysis for all four machine learning models, highlighting the potential of these models in clinical practice to inform patients prior to surgery regarding their expectations of postoperative functional outcomes following primary hip and knee total joint arthroplasty. LEVEL OF EVIDENCE: Level III, case control retrospective analysis.

Machine learning algorithms predict extended postoperative opioid use in primary total knee arthroplasty.

PURPOSE: Adequate postoperative pain control following total knee arthroplasty (TKA) is required to achieve optimal patient recovery. However, the postoperative recovery may lead to an unnaturally extended opioid use, which has been associated with adverse outcomes. This study hypothesizes that machine learning models can accurately predict extended opioid use following primary TKA. METHODS: A total of 8873 consecutive patients that underwent primary TKA were evaluated, including 643 patients (7.2%) with extended postoperative opioid use (> 90 days). Electronic patient records were manually reviewed to identify patient demographics and surgical variables associated with prolonged postoperative opioid use. Five machine learning algorithms were developed, encompassing the breadth of state-of-the-art machine learning algorithms available in the literature, to predict extended opioid use following primary TKA, and these models were assessed by discrimination, calibration, and decision curve analysis. RESULTS: The strongest predictors for prolonged opioid prescription following primary TKA were preoperative opioid duration (100% importance; p < 0.01), drug abuse (54% importance; p < 0.01), and depression (47% importance; p < 0.01). The five machine learning models all achieved excellent performance across discrimination (AUC > 0.83), calibration, and decision curve analysis. Higher net benefits for all machine learning models were demonstrated, when compared to the default strategies of changing management for all patients or no patients. CONCLUSION: The study findings show excellent model performance for the prediction of extended postoperative opioid use following primary total knee arthroplasty, highlighting the potential of these models to assist in preoperatively identifying at risk patients, and allowing the implementation of individualized peri-operative counselling and pain management strategies to mitigate complications associated with prolonged opioid use. LEVEL OF EVIDENCE: IV.

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: The management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of this study is to evaluate the evidence regarding the use of patellar resurfacing in TKA. METHODS: A meta-analysis of randomized controlled trials (RCTs) was performed to compare outcomes between knees receiving patellar resurfacing vs those not receiving resurfacing during primary TKA. Outcomes of interest were the Knee Society Scores, reoperation rates, anterior knee pain, patient satisfaction, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score subscores, and range of motion. RESULTS: Twenty RCTs met all eligibility criteria and were included in the analysis. There were statistically significant differences favoring the resurfaced group in the knee component and functional component of Knee Society Scores that were not clinically significant. There was an increased risk of reoperation among knees that did not receive resurfacing with number needed to treat to prevent one case of reoperation of 25 knees (for reoperation for any reason) and 33 knees (for reoperation for anterior knee pain). There were no statistically significant differences in any other outcomes. CONCLUSION: The only clear relationship is that knees that do not receive patellar resurfacing are more likely to receive reoperation, most often for secondary resurfacing. However, the disease burden of differing complication profiles associated with resurfacing and nonresurfacing groups remains unclear. Continuing to collect data from large, well-designed RCTs would be beneficial in guiding management of the patella during TKA.

A systematic review of peroneal nerve palsy and recovery following traumatic knee dislocation.

PURPOSE: A common peroneal nerve (CPN) palsy has been reported to complicate knee dislocations in 5-40 % of patients. Patients who suffer from a persistent foot drop have significantly worse functional outcomes. Reports on prognostic factors for nerve recovery or treatment-specific functional outcomes remain sparse in the literature. METHODS: Two independent reviewers completed a search of Medline, Embase, PubMed and the Cochrane Library from 1946 to present. Motor strength was determined using the Medical Research Council (MRC) grading system or an equivalent description. A functional recovery was defined as an MRC ≥3/5. RESULTS: The combined search of Medline, Embase, PubMed and the Cochrane Library identified 1528 abstracts. Thirteen articles met our inclusion/exclusion criteria. This included 214 CPN palsies. Functional recovery (MRC ≥3/5) following complete CPN palsy was 38.4 %. Full recovery (MRC = 5/5) following partial CPN palsy was 87.3 %. Younger age was predictive of neurologic recovery. Recovery following isolated neurologic interventions ranged from 0 to 30 %. CONCLUSIONS: A vastly different prognosis can be expected for patients who suffer an incomplete versus a complete CPN palsy. The majority of patients with an incomplete palsy will achieve a full motor recovery while <40 % of patients with a complete motor palsy will regain the ability to dorsiflex at the ankle. While neurologic interventions show promise for the future, the outcomes in knee dislocation patients remain poor. The most predictable means of reestablishing antigravity dorsiflexion in a persistent CPN palsy is a posterior tibial tendon transfer.

The Use of Artificial Neural Networks for the Prediction of Surgical Site Infection Following TKA.

This is a retrospective study. Surgical site infection (SSI) is associated with adverse postoperative outcomes following total knee arthroplasty (TKA). However, accurately predicting SSI remains a clinical challenge due to the multitude of patient and surgical factors associated with SSI. This study aimed to develop and validate machine learning models for the prediction of SSI following primary TKA. This is a retrospective study for patients who underwent primary TKA. Chart review was performed to identify patients with superficial or deep SSIs, defined in concordance with the criteria of the Musculoskeletal Infection Society. All patients had a minimum follow-up of 2 years (range: 2.1-4.7 years). Five machine learning algorithms were developed to predict this outcome, and model assessment was performed by discrimination, calibration, and decision curve analysis. A total of 10,021 consecutive primary TKA patients was included in this study. At an average follow-up of 2.8 ± 1.1 years, SSIs were reported in 404 (4.0%) TKA patients, including 223 superficial SSIs and 181 deep SSIs. The neural network model achieved the best performance across discrimination (area under the receiver operating characteristic curve = 0.84), calibration, and decision curve analysis. The strongest predictors of the occurrence of SSI following primary TKA, in order, were Charlson comorbidity index, obesity (BMI >30 kg/m2), and smoking. The neural network model presented in this study represents an accurate method to predict patient-specific superficial and deep SSIs following primary TKA, which may be employed to assist in clinical decision-making to optimize outcomes in at-risk patients.

Elevated ESR and CRP Prior to Second-Stage Reimplantation Knee Revision Surgery for Periprosthetic Joint Infection Are Associated with Increased Reinfection Rates.

Although two-stage revision surgery is considered as the most effective treatment for managing chronic periprosthetic joint infection (PJI), there is no current consensus on the predictors of optimal timing to second-stage reimplantation. This study aimed to compare clinical outcomes between patients with elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) prior to second-stage reimplantation and those with normalized ESR and CRP prior to second-stage reimplantation. We retrospectively reviewed 198 patients treated with two-stage revision total knee arthroplasty for chronic PJI. Cohorts included patients with: (1) normal level of serum ESR and CRP (n = 96) and (2) elevated level of serum ESR and CRP prior to second-stage reimplantation (n = 102). Outcomes including reinfection rates and readmission rates were compared between both cohorts. At a mean follow-up of 4.4 years (2.8-6.5 years), the elevated ESR and CRP cohort demonstrated significantly higher reinfection rates compared with patients with normalized ESR and CRP prior to second-stage reimplantation (33.3% vs. 14.5%, p < 0.01). Patients with both elevated ESR and CRP demonstrated significantly higher reinfection rates, when compared with patients with elevated ESR and normalized CRP (33.3% vs. 27.6%, p = 0.02) as well as normalized ESR and elevated CRP (33.3% vs. 26.3%, p < 0.01). This study demonstrates that elevated serum ESR and/or CRP levels prior to reimplantation in two-stage knee revision surgery for chronic PJI are associated with increased reinfection rate after surgery. Elevation of both ESR and CRP were associated with a higher risk of reinfection compared with elevation of either ESR or CRP, suggesting the potential benefits of normalizing ESR and CRP prior to reimplantation in treatment of chronic PJI.

Degree of articular injury as measured by CT cross sectional area is associated with physical function following the treatment of bicondylar tibial plateau fractures.

BACKGROUND: Bicondylar tibial plateau fractures are complex injuries that commonly require surgical repair. Long-term clinical outcome has been associated with discrepancies in leg alignment, instability and condylar width abnormalities. While intuitive, the degree of articular damage at time of injury has not been linked to outcomes in patients with bicondylar tibial plateau fractures. The aim of this study was to quantify percentage of articular surface cross sectional area disruption and assess for correlation between the degree of articular injury and patient reported physical function. METHODS: Retrospective cohort study at two level 1 trauma centers. 57 consecutive patients undergoing surgical repair for bicondylar tibial plateau fractures between 2013 and 2016. MAIN OUTCOME MEASURE: Preoperative CT scans were reviewed, and the percentage of articular surface disruption cross sectional area was calculated. PROMIS® scores were collected from patients at a minimum of 2 years. RESULTS: 57 patients with an average age of 58 ± 14.3 years were included. The average PROMIS® score was 45.5. There was a correlation between percentage of articular surface disruption and total PROMIS® scores (0.4, CI: 0.2-0.5, p = .007) and the physical function of the PROMIS® score (0.4, CI: 0.2-0.6, p < .001). CONCLUSION: Our method for calculating articular surface disruption on CT is a simple, reproducible and accurate method for assessing the degree of articular damage in patients with bicondylar tibial plateau fractures. We found that the percentage of cross-sectional articular surface disruption correlates with patient reported outcomes and physical function.

Insurance Payer Type Affects Outcomes after Revision Total Joint Arthroplasty: A Matched Cohort Analysis.

Background: The aim of this study is to evaluate the potential effects of insurance payer type on the postoperative outcomes following revision TJA. Methods: A single-institution database was utilized to identify 4,302 consecutive revision THA and TKA. Patient demographics and indications for revision were collected and compared based on patient insurance payer type: (1) Medicaid, (2) Medicare, and (3) private. Propensity score matching and, subsequent, multivariate regression analyses were applied to control for baseline differences between payer groups. Outcomes of interest were rates of complications occurring perioperatively and 90 days post-discharge. Results: After propensity-score-based matching, a total of 2,328 patients remained for further multivariate regression analyses (300 [12.9%] Medicaid, 1022 [43.9%] Medicare, 1006 [43.2%] private). Compared to privately insured patients, Medicaid and Medicare patients had 71% (P<0.01) and 53% (P=0.03) increased odds, respectively, for developing an in-hospital complication. At 90 days post-discharge, compared to privately insured patients, Medicaid and Medicare patients had 88% and 43% odds, respectively, for developing overall major complications. Conclusion: Our propensity-score-matched cohort study found that, compared to privately insured patients, patients with government-sponsored insurance were at an increased risk for developing both major or minor complications perioperatively and at 90-days post-discharge for revision TJA. This suggests that insurance payer type is an independent risk factor for poor outcomes following revision TJA.

Complications and Soft-Tissue Coverage After Complete Articular, Open Tibial Plafond Fractures.

OBJECTIVES: To evaluate the incidence of nonunion and wound complications after open, complete articular pilon fractures. Second, to study the effect that both timing of fixation and timing of flap coverage have on deep infection rates. DESIGN: Retrospective case series. SETTING: Three Academic Level 1 Trauma Centers. PATIENTS: One hundred sixty-one patients with open OTA/AO type 43C distal tibia fractures treated with open reduction internal fixation (ORIF) between 2002 and 2018. The mean (SD) age was 46 (14) years, 70% male, with median (interquartile range) follow-up of 2.1 (1.3-5.0) years (minimum 1 year). There were 133 (83%) type 3A and 28 (17%) type 3B open fractures. INTERVENTION: Fracture fixation: acute, primary (<24 hours) versus delayed, staged ORIF (>24 hours). Soft-tissue coverage: rotational or free flap. MAIN OUTCOME MEASUREMENT: Primary outcomes included deep infection and nonunion. Secondary outcomes included rates of soft-tissue coverage and reoperation. RESULTS: Acute fixation (<24 hours) was performed in 36 (22%) patients; 125 (78%) underwent delayed, staged fixation. Deep infection occurred in 27% patients and was associated with men (33% vs. 16%, P = 0.029), smoking (38% vs. 23%, P = 0.047), and type 3B fractures (39% vs. 25%, P = 0.046). Acute fixation of type 3A fractures demonstrated a higher rate of infection (38% vs. 20% P = 0.036) than delayed, staged fixation. In type 3B fractures, early flap coverage (<1 week) demonstrated a lower rate of infection (18% vs. 53%, P = 0.066) and 20% (vs. 43%) with a single-staged "fix and flap" procedure (P = 0.408). Nonunion occurred in 36 (22%) and was associated with deep infection (43% vs. 15%, P < 0.001). Fifteen (42%) were septic nonunions. Twenty-nine of the 36 (81%) nonunions achieved radiographic union after median (interquartile range) 27 (20-41) weeks and median (range) 1 (1-3) revision ORIF procedures. There was no difference in the rate of secondary union between septic and aseptic nonunions (85% vs. 86%, P = 1.00). There was a high rate of secondary procedures (47%): revision ORIF (17%), irrigation and debridement (15%), and removal of implants (11%). CONCLUSIONS: Complete articular, open pilon fractures are associated with a high rate of complications after ORIF. Early fixation carries a high risk of deep infection; however, early flap coverage for 3B fractures seems to play a protective role. We advocate for aggressive management including urgent surgical debridement and very early soft-tissue cover combined with definitive fixation during single procedure if possible. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Judicious Use of Early Fixation of Closed, Complete Articular Pilon Fractures Is Not Associated With an Increased Risk of Deep Infection or Wound Complications.

OBJECTIVES: To compare the deep infection rates after immediate versus staged open reduction internal fixation (ORIF) for pilon fractures. DESIGN: Retrospective cohort study. SETTING: Three academic Level I trauma centers. PATIENTS: Four hundred one patients with closed OTA/AO type 43C distal tibia fractures treated with ORIF. Sixty-six percent were men, and the mean age was 45.6 years. The median (interquartile range) follow-up was 1.7 (1.0-3.7) years. INTERVENTION: Acute, primary (<24 hours) versus delayed, staged ORIF (>24 hours). MAIN OUTCOME MEASUREMENT: Deep infection or wound complication as defined by return to operating room for surgical irrigation and debridement. RESULTS: Patients were grouped by time from presentation to surgery: acute ORIF (n = 99) and delayed ORIF (n = 302). Acute ORIF was more frequent in patients with OTA/AO type 43C1 fractures, low-energy mechanisms (ie, fall from standing), younger and female patients. Patients who demonstrated severe swelling (242, 80%), swelling and fracture blisters (26, 9%), swelling and ecchymosis precluding planned surgical approach (4, 1%), polytrauma requiring resuscitation (20, 6%), who were transferred from an outside facility with external fixator in place (6, 2%), who had evolving compartment syndrome (2, 1%), and who required medical clearance (2, 1%) underwent staged, delayed fixation. There were significantly more 43C1 fractures in the acute fixation group (31% vs. 7%, P < 0.001) and significantly more 43C3 fractures in the delayed group (63% vs. 37%, P < 0.001). The overall deep infection rate was 17%. Early surgery was not associated with an increased risk of postoperative wound complication (early 12% vs. delayed 18%, P = 0.235). Multivariate analysis adjusted for timing of surgery found high-energy trauma [odds ratio (OR) 4.0, 95% confidence interval (CI) 1.1-13.8], smoking (OR 2.4, CI 1.3-4.6), male sex (OR 2.1, CI 1.0-4.1), and increasing age (OR 1.02, CI 1.00-1.04, P = 0.040) to be independent predictors of deep infection. Diabetes demonstrated a nonstatistically significant increased risk (OR 2.6, 95% CI 0.9-7.3, P = 0.063). CONCLUSIONS: This study confirms the high risk of infection after the fixation of tibial plafond fractures. If early definitive fixation is considered, extreme care should be taken to carefully evaluate the soft tissue envelope and assess for other risk factors (such as age, male sex, smokers, diabetics, and those with higher-energy fracture patterns) that may predispose the patient to a postoperative soft tissue infection. Our study has shown that the judicious use of early definitive fixation in closed pilon fractures, in the appropriate patient, and with careful evaluation of the soft tissue envelope, is likely safe and does not seem to increase the risk of wound complications and deep infection in the hands of experienced fracture surgeons. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Does Surgical Approach Influence the Risk of Postoperative Infection After Surgical Treatment of Tibial Pilon Fractures?

OBJECTIVES: To determine whether a particular surgical approach or combination of approaches is a risk factor for infection. DESIGN: Retrospective review. SETTING: Two Level-1 trauma centers. PATIENTS/PARTICIPANTS: Five hundred ninety pilon fractures in 581 patients (66% male) with a median age of 45 years were identified. INTERVENTION: Open reduction internal fixation of pilon fractures. MAIN OUTCOME MEASURES: Postoperative deep surgical site infection and risk factors for postoperative deep infection. RESULTS: The most common primary surgical approach was medial (54%), followed by anterolateral (25%), anteromedial (11%), posterolateral (8%), and posteromedial (2%). A dual approach to the distal tibia was used in 18% of the cases. The overall deep infection rate was 19%. There was no association between primary surgical approach and development of infection (P = 0.19-0.78). Independent risk factors for infection were smoking (hazard ratio, 2.1; P < 0.001) and need for soft tissue coverage (hazard ratio, 6.9; P < 0.001). CONCLUSIONS: Surgical approach does not appear to be a significant risk factor for postoperative infection after open reduction internal fixation of distal tibial pilon fractures. When treating tibial plafond fractures, surgeons should select the approach they feel best addresses the specific fracture pattern. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Is the proximity of external fixator pins to eventual definitive fixation implants related to the risk of deep infection in the staged management of tibial pilon fractures?

INTRODUCTION: In the staged management of tibial pilon fractures, overlap between definitive internal fixation and external fixation pin sites has been investigated as a risk factor for infection with equivocal conclusions. Our aim was to determine if overlap or proximity of definitive internal fixation to external fixation pin sites influences the risk of deep infection. PATIENTS AND METHODS: We reviewed 280 AO/OTA 43B or 43C type distal tibia fractures in 277 patients at two level-one trauma centers. Patients underwent staged management using early temporizing external fixation followed by definitive open reduction and plate fixation. Primary outcome was the association between pin site overlap and the development of deep infection. Secondary outcome was the relationship between development of deep infection and the distance from pin site to definitive fixation. RESULTS: The average duration between external fixation and definitive internal fixation was 14 days. 24% of fractures developed deep infection requiring surgical intervention. There was no association between pin site overlap and the development of deep infection (p = 0.18). There was no relationship between infection and the distance between proximal plate extent and pin site (p = 0.13). DISCUSSION: We identified no association between pin site overlap and the development of deep infection. We suggest that temporizing external fixation pins should be placed so as to obtain optimal stability of the construct with lesser emphasis on aiming to be absolutely outside the zone of future fixation. LEVEL OF EVIDENCE: Level III Therapeutic Retrospective Comparative study.

Phasic electrodermal responses associated with whole-body instability: presence and influence of expectation.

While much is understood about somatic contributions to postural control, there is less consideration for the potential involvement of the autonomic nervous system (ANS) as integral for maintenance of stability. The purpose of this study was to examine autonomic responses, as measured through electrodermal recordings, evoked in response to whole-body perturbations to standing balance. We hypothesized that phasic electrodermal responses (EDRs) would be consistently observed in response to evoked perturbations and that response amplitude would depend on the capacity to predict perturbation timing. Temporally unpredictable and self-initiated (predictable) backward perturbations evoked in healthy participants (n=15) elicited compensatory feet-in-place reactions with tibialis anterior activation 125.1+/-60.2 ms following perturbation onset. EDRs were consistently observed starting 1883.6+/-329.1 ms after perturbation and reaching their peak at 4016.6+/-896.9 ms. Amplitude was significantly larger in the unpredictable task (1.1+/-0.84 micromho) compared to the predictable task (0.45+/-0.55 micromho, P<0.001). Amplitude was largest in the first block of five trials (P<0.0001), then remained constant for subsequent trials in each condition. Post-hoc analysis indicated that trials with an unplanned compensatory step (3.5%) were 137.0+/-176.6% larger than feet-in-place reactions (P=0.02). Elevated EDRs during initial trials and unanticipated reactions suggest that these measures could be used to assess the perceived 'novelty' of applied perturbations, having implications for interpreting characteristics of the evoked somatic reactions. The persistence of perturbation-evoked EDRs even after thirty trials may also highlight an important role for phasic ANS responses in compensatory postural control.

Comparison of body composition assessment methods in patients with human immunodeficiency virus-associated wasting receiving growth hormone.

CONTEXT: Bioelectrical impedance spectroscopy (BIS) and skinfold anthropometry (SKF) have been used to monitor body composition among patients with HIV wasting; however, validation of these techniques during recombinant human GH (rhGH) treatment has not been performed. OBJECTIVE: Our objective was to evaluate the degree of agreement between criterion measurements of dual-energy x-ray absorptiometry (DXA) and those of BIS and SKF in patients with HIV wasting treated with rhGH. DESIGN AND SETTING: We conducted a randomized, double-blinded, placebo-controlled, two-period crossover trial at the University of Toronto and Mount Sinai Hospital (Toronto, Canada). PATIENTS: A referred sample of 27 community-dwelling men with HIV-associated weight loss (> or =10% over preceding 12 months) despite optimal antiretroviral therapy participated in the study. INTERVENTION: Intervention was one daily injection of rhGH (6 mg) or placebo self-administered for 3 months in a crossover fashion with a 3-month washout. MAIN OUTCOME MEASURES: Fat-free mass (FFM) and fat mass (FM) were measured by BIS, SKF, and DXA before and after rhGH and placebo treatment. RESULTS: FFM(BIS) was not significantly different from FFM(DXA) after rhGH treatment (P = 0.10). Mean differences (bias +/- sd) according to Bland-Altman analysis were smaller for SKF than for BIS (P < 0.05) at all time points, yet treatment-induced change in FM was better detected with BIS than with SKF. BIS estimates of FFM and FM showed better agreement with those of DXA after rhGH treatment (1.6 +/- 4.6 kg and -2.1 +/- 3.9 kg) compared with baseline (3.8 +/- 3.5 kg and -4.1 +/- 3.6 kg) and placebo (2.7 +/- 4.4 kg and -3.1 +/- 4.6) (P < 0.05). BIS overestimated and SKF underestimated the treatment-induced changes in FFM and FM. CONCLUSIONS: SKF was more accurate than BIS when measuring body composition in patients with HIV wasting before and after rhGH treatment; nonetheless, the accuracy of BIS increased after treatment. Change in FM because of treatment was not accurately assessed with SKF.

Complications following arthroscopic fixation of acromioclavicular separations: a systematic review of the literature.

PURPOSE: Over the past decade, a number of arthroscopic or arthroscopically assisted reconstruction techniques have emerged for the management of acromioclavicular (AC) separations. These techniques provide the advantage of superior visualization of the base of the coracoid, less soft tissue dissection, and smaller incisions. While these techniques have been reported to provide excellent functional results with minimal complications, discrepancies exist within the literature. This systematic review aims to assess the rate of complications following these procedures. METHODS: Two independent reviewers completed a search of Medline, Embase, PubMed, and the Cochrane Library entries up to December 2013. The terms "Acromioclavicular Joint (MeSH)" OR "acromioclavicular* (text)" OR "coracoclavicular* (text)" AND "Arthroscopy (MeSH)" OR "Arthroscop* (text)" were used. Pooled estimates and 95% confidence intervals were calculated assuming a random-effects model. Statistical heterogeneity was quantified using the I(2) statistic. LEVEL OF EVIDENCE: IV. RESULTS: A total of 972 abstracts met the search criteria. After removal of duplicates and assessment of inclusion/exclusion criteria, 12 articles were selected for data extraction. The rate of superficial infection was 3.8% and residual shoulder/AC pain or hardware irritation occurred at a rate of 26.7%. The rate of coracoid/clavicle fracture was 5.3% and occurred most commonly with techniques utilizing bony tunnels. Loss of AC joint reduction occurred in 26.8% of patients. CONCLUSION: Arthroscopic AC reconstruction techniques carry a distinct complication profile. The TightRope/Endobutton techniques, when performed acutely, provide good radiographic outcomes at the expense of hardware irritation. In contrast, graft reconstructions in patients with chronic AC separations demonstrated a high risk for loss of reduction. Fractures of the coracoid/clavicle remain a significant complication occurring predominately with techniques utilizing bony tunnels.

Exercise training benefits growth hormone (GH)-deficient adults in the absence or presence of GH treatment.

Reduced aerobic capacity is a prominent manifestation among patients with GH deficiency (GHD). Exercise training may improve the physiological capacity to undertake aerobic activity. The ability of patients with GHD to participate in and benefit from a structured program of aerobic exercise with or without replacement recombinant human GH (rhGH) was investigated. We examined the effect of aerobic training on cycle ergometers in a double-blind crossover trial. Ten patients with GHD trained for 3 months with rhGH (6 microg/kg.d) or placebo, stopped both exercise and drug for 2 months, and resumed training for another 3 months with the other agent. Peak oxygen uptake (VO(2)peak) and ventilation threshold (VeT) were measured during a progressive cycle ergometer test to fatigue or symptom-limited maximum. Serum IGF-I levels were monitored to assess compliance with GH treatment. VO(2)peak was low at the two baseline measures (B1, 19.3 +/- 5.5; B2, 19.9 +/- 6.9 ml/kg.min; normal, approximately 30 ml/kg.min) as was VeT (B1, 11.6 +/- 2.2 ml/kg.min; B2, 11.7 +/- 2.6 ml/kg.min; normal, approximately 16 ml/kg.min). Exercise training increased VeT with (8.6%) or without (9.4%) rhGH treatment. Similarly, exercise training resulted in significant reduction in submaximal heart rate in the presence (-5 +/- 4 beats per minute; P < 0.05) or absence of rhGH treatment (-4 +/- 4 beats per minute; P < 0.05). Peak oxygen uptake was not significantly affected by training with or without rhGH treatment. Our findings suggest that exercise training is a feasible intervention in GH-deficient adults that can measurably improve their submaximal responses to exercise. The beneficial effects of exercise can mimic and are not additive to the effects of GH treatment alone.