Mid-term outcomes of temporary medial distal femoral hemiepiphysiodesis with and without medial patellofemoral ligament repair for recurrent patellar instability in skeletally immature patients with genu valgum.

Genu valgum contributes to patellar instability, though outcomes following temporary hemiepiphysiodesis via eight plating are less understood. The purpose of this study was to evaluate the outcomes and need for additional procedures following temporary hemiepiphysiodesis for the treatment of pediatric genu valgum and patellar instability, as well as evaluating the utility of a concurrent medial patellofemoral ligament (MPFL) repair. Patients who underwent medial distal femoral epiphysiodesis for the treatment of genu valgum and recurrent patellar instability were identified. Inclusion criteria were minimum 1-year follow-up and lack of concurrent ligamentous reconstruction. Patients were contacted to complete a questionnaire which included the International Knee Documentation Committee (IKDC) form and questions pertaining to knee function and patient satisfaction. Thirty-one patients aged 12.0 ± 1.9 years underwent 47 guided growth procedures and were included in final analysis. Seventeen knees (36%) required subsequent surgery for patellar instability. All patients requiring subsequent surgery were female, compared with 70% of patients not requiring subsequent surgery ( P  = 0.017). The MPFL repair group underwent fewer subsequent procedures to address instability, though this difference was NS (17 vs. 46%, P  = 0.318). Mean IKDC score at 5.3 years follow-up among 18 survey respondents was 78.6. Medial distal femoral hemiepiphysiodesis may partially address recurrent patellar instability in skeletally immature patients with genu valgum. Concurrent MPFL repair may minimize the need for subsequent procedures to address recurrent instability. While correcting alignment may be helpful, patients should be aware of the potential need for further patellar instability surgery. Level of evidence: IV, case series.

Analysis of acute extremity compartment syndrome using a genealogic population database.

INTRODUCTION: Acute extremity compartment syndrome ("CS") is an under-researched, highly morbid condition affecting trauma populations. The purpose of this study was to analyze incidence rates and risk factors for extremity compartment syndrome using a high-quality population database. Additionally, we evaluated heritable risk for CS using available genealogic data. We hypothesized that diagnosis of extremity compartment syndrome would demonstrate heritability. MATERIALS AND METHODS: Adult patients with fractures of the tibia, femur, and upper extremity were retrospectively identified by ICD-9, ICD-10, and CPT codes from 1996 to 2020 in a statewide hospital database. Exposed and unexposed cohorts were created based on a diagnosis of CS. Available demographic data were analyzed to determine risk factors for compartment syndrome using logistic regression. Mortality risk at the final follow-up was evaluated using Cox proportional hazard modeling. Patients with a diagnosis of CS were matched with those without a diagnosis for heritability analysis. RESULTS: Of 158,624 fractures, 931 patients were diagnosed with CS. Incidence of CS was 0.59% (tibia 0.83%, femur 0.31%, upper extremity 0.27%). Male sex (78.1% vs. 46.4%; p < 0.001; RR = 3.24), younger age at fracture (38.8 vs. 48.0 years; p < 0.001; RR = 0.74), Medicaid enrollment (13.2% vs. 9.3%; p < 0.001; RR = 1.58), and smoking (41.1% vs. 31.1%; p < 0.001; RR 1.67) were significant risk factors for CS. CS was associated with mortality (RR 1.61, p < 0.001) at mean follow-up 8.9 years in the CS cohort. No significant heritable risk was found for diagnosis of CS. CONCLUSIONS: Without isolating high-risk fractures, rates of CS are lower than previously reported in the literature. Male sex, younger age, smoking, and Medicaid enrollment were independent risk factors for CS. CS increased mortality risk at long-term follow-up. No heritable risk was found for CS. LEVEL OF EVIDENCE: III.

Return to Skiing After Tibial Plateau Fracture.

Background: Tibial plateau fractures in skiers are devastating injuries with increasing incidence. Few studies have evaluated patient-reported outcomes and return to skiing after operative fixation of a tibial plateau fracture. Purpose: To (1) identify demographic factors, fracture characteristics, and patient-reported outcome measures that are associated with return to skiing and (2) characterize changes in skiing performance after operative fixation of a tibial plateau fracture. Study Design: Case series; Level of evidence, 4. Methods: We reviewed all operative tibial plateau fractures performed between 2016 and 2021 at a single level-1 trauma center. Patients with a minimum of 10-month follow-up data were included. Patients who self-identified as skiers or were injured skiing were divided into those who returned to skiing and those who did not postoperatively. Patients were contacted to complete the Patient-Reported Outcomes Measurement Information System-Physical Function domain (PROMIS-PF), the Knee injury and Osteoarthritis Outcome Score-Activities of Living (KOOS-ADL), and a custom return-to-skiing questionnaire. Multivariate logistic regression was performed with sex, injury while skiing, PROMIS-PF, and KOOS-ADL as covariates to evaluate factors predictive of return to skiing. Results: A total of 90 skiers with a mean follow-up of 3.4 ± 1.5 years were included in the analysis. The rate of return to skiing was 45.6% (n = 41). The return cohort was significantly more likely to be men (66% vs 41%; P = .018) and injured while skiing (63% vs 39%; P = .020). In the return cohort, 51.2% returned to skiing 12 months postoperatively. The percentage of patients who self-reported skiing on expert terrain dropped by half from pre- to postinjury (61% vs 29.3%, respectively). Only 78% of return skiers had regained comfort with skiing at the final follow-up. Most patients (65%) felt the hardest aspect of returning to skiing was psychological. In the multivariate regression, the male sex and KOOS-ADL independently predicted return to skiing (P = .006 and P = .028, respectively). Conclusion: Fewer than half of skiers who underwent operative fixation of a tibial plateau fracture could return to skiing at a mean 3-year follow-up. The knee-specific KOOS-ADL outperformed the global PROMIS-PF in predicting a return to skiing.

Familial Analysis of Nonunion in a Genealogic Population Database Demonstrates No Evidence of Heritable Risk.

OBJECTIVE: To determine whether there is evidence of heritable risk for nonunion using a large, state-wide population database. DESIGN: Database. SETTING: Level 1 Trauma Center. POPULATION: All Utah residents from 1996 to 2021 who sustained a long bone fracture and their family members were included. OUTCOMES: The primary outcome was nonunion and the prevalence of nonunion among the patients' first-, second-, and third-degree relatives. The secondary objective was to identify demographic, injury, and socioeconomic risk factors associated with nonunion. RESULTS: In total, 150,263 fractures and 6577 nonunions (4.4%) were identified. This was highly refined to a 1:3 matched cohort of 4667 nonunions of 13,981 fractures for familial clustering analysis. Cox proportional hazards did not demonstrate excessive risk of nonunion among first- ( P = 0.863), second- ( P = 0.509), and third-degree relatives ( P = 0.252). Further analysis of the entire cohort demonstrated that male sex (relative risk [RR] = 1.15; P < 0.001), Medicaid enrollment (RR = 2.64; P < 0.001), open fracture (RR = 2.53; P < 0.001), age group 41-60 years (RR = 1.43; P < 0.001), and a history of obesity (RR = 1.20; P < 0.001) were independent risk factors for nonunion. CONCLUSIONS: Our results demonstrate no evidence of heritable risk for nonunion. Independent risk factors for nonunion were male sex, Medicaid enrollment, open fracture, middle age, and a history of obesity. Although it is important to identify modifiable and nonmodifiable risk factors, these results continue to support that the risk of nonunion is multifactorial, relating to injury characteristics, operative techniques, and patient-specific risk factors. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Tibial Plateau Fractures Complicated by Compartment Syndrome Are Associated With a 3 Times Higher Cost of Care.

OBJECTIVES: To determine the impact of acute compartment syndrome (ACS) and identify cost drivers of 1-year total treatment costs for operative tibial plateau fractures. DESIGN: Retrospective review. SETTING: Level 1 trauma center. PATIENTS: 337 patients with tibial plateau fractures, 24 of which were complicated by ACS. OUTCOMES: The primary outcome was total treatment cost over the first year for operatively treated tibial plateau fractures. The secondary objective was to use regression analysis to identify significant cost drivers. RESULTS: The diagnosis of ACS was associated with 2.85 times higher total treatment cost ( P < 0.001). ACS demonstrated increased total treatment cost when controlling for polytrauma ( P < 0.001) and postoperative infection ( P < 0.001). Regression analysis identified 5 variables significantly associated with total cost of care: body mass index, injury severity score, ACS, staged external fixation, and locking fixation ( P < 0.001; R 2 = 0.57). The diagnosis of ACS had the largest impact on total cost with a 3.5× greater impact on cost compared with the next highest variable, staged external fixation. CONCLUSIONS: Tibial plateau fractures complicated by ACS are associated with 2.85 times higher treatment costs over a 1-year period. There were 5 significant variables identified by regression analysis with ACS having the highest impact on total treatment. Together, these 5 factors account for 57% of treatment cost variability. LEVEL OF EVIDENCE: Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

What Happens on the Back Table? Viability and Osteogenic Potential of Reamed Autogenous Bone Graft as a Function of Time and Temperature-A Pilot Study.

OBJECTIVES: To provide guidelines for reamed autogenous bone graft (R-ABG) in nonunion surgery to best manage modifiable intraoperative factors, like storage temperature and time, for optimal graft viability. Our hypothesis was that R-ABG graft will show decreased cell viability as a function of increased time and storage temperature. METHODS: R-ABG samples were obtained using an RIA system from 10 patients undergoing harvest for the treatment of a nonunion. A 10 cm3 sample of cancellous bone graft was divided into 10 samples. A control sample was processed immediately and analyzed using fluorescence activated cell sorting to determine its cell viability. The remaining samples were stored at 0, 15, and 37°C and processed similarly after 60 and 120 minutes. A paired t test was used to compare the mean change in percent viability. RESULTS: The mean percent cell viability for the experimental conditions was not significantly different from the initial percent cell viability (P ≥ 0.08). There were no significant differences in the change in mean percentage of viable cells (P ≥ 0.07). After 60 and 120 minutes of storage, there were no significant differences in mean cell viability based on storage temperature (P ≥ 0.53 and P ≥ 0.68, respectively). A power analysis estimated that a sample size of 52 patients would be needed to detect a difference. CONCLUSIONS: The results of our pilot study indicate that storage conditions may have less effect on cell viability than previously hypothesized. Further research with more patients is needed to confirm these preliminary results. LEVEL OF EVIDENCE: Level II.

Biomechanical assessment of docking ulnar collateral ligament reconstruction after failed ulnar collateral ligament repair with suture augmentation.

BACKGROUND: Ulnar collateral ligament (UCL) repair with single-strand suture augmentation has been introduced as a viable surgical option for throwers with acute UCL tears. For the original single-strand suture augmentation construct, revision UCL reconstructions can be challenging owing to the bone loss at the site of anchor insertion in the center of the sublime tubercle. This biomechanical study assessed a small-diameter (1.5-mm) ulnar bone tunnel technique for double-strand suture-augmented UCL repair that may be more easily converted to salvage UCL reconstruction if necessary, as well as a salvage UCL reconstruction with a docking technique after a failed primary suture-augmented UCL repair. METHODS: In 7 fresh-frozen cadaveric upper extremities (mean age, 66.3 years), a custom shoulder testing system was used to simulate the late cocking phase of throwing. The elbow valgus opening angle was evaluated using a MicroScribe 3DLX device for sequentially increasing valgus torque (from 0.75 to 7.5 Nm in 0.75-Nm increments) at 90° of flexion. Valgus angular stiffness (in newton-meters per degree) was defined as the correlation of sequentially increasing valgus torque with the valgus opening angle through simple linear regression (slope of valgus torque - valgus opening angle curve). Four conditions were tested: intact elbow, distal UCL avulsion, primary UCL repair with double-strand suture augmentation using small-diameter bone tunnels, and subsequent docking UCL reconstruction in the same specimen. Load-to-failure tests were performed for primary UCL repair with double-strand suture augmentation and subsequent docking UCL reconstruction. RESULTS: With increasing elbow valgus torque, the valgus opening angle increased linearly in each condition (R2 ≥ 0.98, P < .001). Distal UCL avulsion resulted in significantly decreased angular stiffness compared with the intact UCL (P < .001). Both UCL repair with double-strand suture augmentation and subsequent UCL reconstruction showed significantly increased angular stiffness values compared with distal UCL avulsion (P < .001 and P < .001, respectively). On load-to-failure testing, there was no significant difference in stiffness, yield torque, and ultimate torque between the primary suture-augmented UCL repair and the subsequent UCL reconstruction (P = .11, P = .77, and P = .38, respectively). In all specimens undergoing the small-diameter ulnar bone tunnel technique for double-strand suture-augmented UCL repair, failure occurred by retear of the repaired ligament without causing an ulnar bone bridge fracture. CONCLUSION: Primary UCL repair with double-strand suture augmentation using small-diameter bone tunnels was able to restore valgus stability. When failure occurs, this technique retains enough cortical bone to permit subsequent docking UCL reconstruction.

Complication Rates after Lateral Plate Fixation of Periprosthetic Distal Femur Fractures: A Multicenter Study.

OBJECTIVE: Periprosthetic fractures of the distal femur can be challenging injuries to treat; nonunion rates of up to 22% have been reported. The purpose of this study was to determine the rate of complications and nonunion in a multicenter series, and to identify patient or surgical factors that were associated with nonunion. DESIGN: Retrospective comparative study SETTING: Three Level 1 trauma centers PATIENTS: Fifty-five patients with a periprosthetic distal femur fracture proximal to a total knee arthroplasty. Minimum follow up for inclusion was six months or until union or failure. INTERVENTION: Surgical fixation using a precontoured lateral locking plate MAIN OUTCOME MEASUREMENT: Fracture union was the primary outcome. Patient demographic and injury variables (age, comorbidities, fracture classification and characteristics) and surgical technique factors (mode of plate fixation, plate material, working length, screw density, and proximal screw type) were identified and compared between patients who developed a nonunion and those who did not. Regression analysis was performed to identify independent risk factors for nonunion. RESULTS: The overall rate of nonunion was 18% and the total complication rate was 24%. After additional surgery, 49 of 55 patients went on to heal (89%). There were no statistical differences in patient demographic or injury variables between the union and nonunion groups, and none of the variables studied were independent risk factors for nonunion in the regression analysis. CONCLUSIONS: In this series of 55 patients with periprosthetic distal femur fractures treated with precontoured lateral locking plates, 18% developed nonunion and the overall complication rate was 24%. No patient or surgical variables were identified as risk factors. Future research should seek to identify patients at high risk for complication and nonunion who could benefit from alternative fixation strategies or distal femoral replacement.

Aquatic microbial habitats within a neotropical rainforest: bromeliads and pH-associated trends in bacterial diversity and composition.

Tank-forming bromeliads, suspended in the rainforest canopy, possess foliage arranged in compact rosettes capable of long-term retention of rainwater. This large and unique aquatic habitat is inhabited by microorganisms involved in the important decomposition of impounded material. Moreover, these communities are likely influenced by environmental factors such as pH, oxygen, and light. Bacterial community composition and diversity was determined for the tanks of several bromeliad species (Aechmea and Werauhia) from northern Costa Rica, which span a range of parameters, including tank morphology and pH. These were compared with a nearby forest soil sample, an artificial tank (amber bottle), and a commercially available species (Aechmea). Bacterial community diversity, as measured by 16S rRNA analysis and tRFLP, showed a significant positive correlation with tank pH. A majority of 16S rRNA bacterial phylotypes found in association with acidic bromeliad tanks of pH < 5.1 were affiliated with the Alphaproteobacteria, Acidobacteria, Planctomycetes, and Bacteroidetes, and were similar to those found in acidic peat bogs, yet distinct from the underlying soil community. In contrast, bromeliads with tank pH > 5.3, including the commercial bromeliad with the highest pH (6.7), were dominated by Betaproteobacteria, Firmicutes, and Bacteroidetes. To empirically determine the effect of pH on bacterial community, the tank pH of a specimen of Aechmea was depressed, in the field, from 6.5 to 4.5, for 62 days. The resulting community changed predictably with decreased abundance of Betaproteobacteria and Firmicutes and a concomitant increase in Alphaproteobacteria and Acidobacteria. Collectively, these results suggest that bromeliad tanks provide important habitats for a diverse microbial community, distinct from the surrounding environment, which are influenced greatly by acid-base conditions. Additionally, total organic carbon (∼46%) and nitrogen (∼2%) of bromeliad-impounded sediment was elevated relative to soil and gene surveys confirmed the presence of both chitinases and nitrogenases, suggesting that bromeliad tanks may provide important habitats for microbes involved in the biological cycling of carbon and nitrogen in tropical forests.