Risk Factors of Failure in 228 Periprosthetic Distal Femur Fractures: A Multicenter Study.

OBJECTIVES: To identify risk factors of reoperation to promote union or to address deep surgical-site infection (DSSI) in periprosthetic distal femur fractures treated with lateral distal femoral locking plates (LDFLPs). DESIGN: Multicenter retrospective cohort study. SETTING: Ten level-I trauma centers. PATIENT SELECTION CRITERIA: Patients with Orthopaedic Trauma Association/Association of Osteosynthesis (OTA/AO) 33A or 33C periprosthetic distal femur fractures who underwent surgical fixation between January 2012 and December 2019 exclusively using LDFLPs were eligible for inclusion. Patients with pathologic fractures or with follow-up less than 3 months without an outcome event (unplanned reoperation to promote union or for deep surgical infection) before this time point were excluded. Fracture fixation constructs used medial plates, intramedullary nails, or hybrid fixation constructs were excluded from analysis. OUTCOME MEASURES AND COMPARISONS: To examine the influence of patient demographics, injury characteristics, and features of the fracture fixation construct on the occurrence of unplanned reoperation to promote union or to address a DSSI. RESULTS: There was an 8.3% rate (19/228) of unplanned reoperation to promote union. Predictive factors for the need for reoperation to promote union included increasing body mass index (odds ratio [OR] = 1.09; 95% confidence interval [CI]: 1.02-1.16; P = 0.01), increasing number of screws in the distal fracture segment (OR = 1.73; 95% CI: 1.06-2.95; P = 0.03), and decreasing proportion of proximal segment screws that are locking (OR = 0.17; 95% CI: 0.03-0.70; P = 0.02) There was a 4.8% rate (11/228) of reoperation to address DSSI. There were no statistically significant predictive factors identified as risk factors of the need for reoperation to address DSSI ( P > 0.05). CONCLUSIONS: 8.3% of periprosthetic distal femur fractures treated at 10 centers with LDFLPs underwent unplanned reoperation to promote union. Increasing patient body mass index and increasing number of screws in the distal fracture segment were found to be predictive factors, whereas increased locking screws in the proximal segment were found to be protective. 4.8% of patients in this cohort underwent reoperation to address DSSI. LEVEL OF EVIDENCE: Level III. See Instructions for Authors for a complete description of levels of evidence.

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.

Meniscus Tear Requiring Intraoperative Repair Does Not Influence Midterm Patient-Reported Outcomes in Operatively Treated Tibial Plateau Fractures.

OBJECTIVES: Evaluate whether intraoperatively repaired lateral meniscus injuries impact midterm patient-reported outcomes in those undergoing operative fixation of tibial plateau fracture. DESIGN: Retrospective cohort study. SETTING: Level I trauma center. PATIENT SELECTION CRITERIA: All patients (n = 207) who underwent operative fixation of a tibial plateau fracture from 2016 to 2021 with a minimum of 10-month follow-up. OUTCOME MEASURES AND COMPARISONS: The Patient-Reported Outcomes Measurement Information System Physical Function, Knee Injury and Osteoarthritis Outcome Score, and the PROMIS-Preference health utility score. RESULTS: Overall, 207 patients were included with average follow-up of 2.9 years. Seventy-three patients (35%) underwent intraoperative lateral meniscus repair. Gender, age, body mass index, Charlson comorbidity index, days to surgery, ligamentous knee injury, open fracture, vascular injury, polytraumatic injuries, Schatzker classification, and Orthopaedic Trauma Association classification were not associated with meniscal repair ( P > 0.05). Rates of reoperation (42% vs. 31%, P = 0.11), infection (8% vs. 10%, P = 0.60), return to work (78% vs. 75%, P = 0.73), and subsequent total knee arthroplasty (8% vs. 5%, P = 0.39) were also similar between those who had a meniscal repair and those without a meniscal injury, respectively. There was no difference in Patient-Reported Outcomes Measurement Information System Physical Function (46.3 vs. 45.8, P = 0.707), PROMIS-Preference (0.51 vs. 0.50, P = 0.729), and all Knee Injury and Osteoarthritis Outcome Score domain scores at the final follow-up between those who had a meniscal repair and those without a meniscal injury, respectively. CONCLUSIONS: In patients with an operatively treated tibial plateau fracture, the presence of a concomitant intraoperatively identified and repaired lateral meniscal tear results in similar midterm PROMs and complication rates when compared with patients without meniscal injury. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Worse Quality of Life Associated With Hyperextension Varus Tibial Plateau Fracture Pattern.

OBJECTIVES: Compare patient-reported outcome measures between hyperextension varus tibial plateau (HEVTP) fracture patterns to non-HEVTP fracture patterns. DESIGN: Retrospective study. SETTING: Single academic Level 1 Trauma Center. PATIENT SELECTION CRITERIA: All patients who underwent fixation of a tibial plateau fracture from 2016 to 2021 were collected. Exclusion criteria included inaccurate Current Procedural Terminology code, ipsilateral compartment syndrome, bilateral fractures, incomplete medical records, or follow-up <10 months. OUTCOME MEASURES AND COMPARISONS: In patients who underwent fixation of a tibial plateau fracture, compare Patient-Reported Outcomes Measurement Information System-Physical Function, PROMIS Preference, and Knee Injury and Osteoarthritis Outcome Score (KOOS) between patients with a HEVTP pattern with those without. RESULTS: Two-hundred and seven patients were included, of which 17 (8%) had HEVTP fractures. Compared with non-HEVTP fracture patterns, patients with HEVTP injuries were younger (42.6 vs. 51.0, P = 0.025), more commonly male (71% vs. 44%, P = 0.033), and had higher body mass index (32.8 vs. 28.0, P = 0.05). HEVTP fractures had significantly more ligamentous knee (29% vs. 6%, P = 0.007) and vascular (12% vs. 1%, P = 0.035) injuries. Patient-Reported Outcomes Measurement Information System-Physical Function scores were similar between groups; however, PROMIS-Preference (0.37 vs. 0.51, P = 0.017) was significantly lower in HEVTP fractures. KOOS pain, activities of daily living, and quality-of-life scores were statistically lower in HEVTP fractures, but only KOOS quality-of-life was clinically relevant (41.7 vs. 59.3, P = 0.004). CONCLUSIONS: The HEVTP fracture pattern, whether unicondylar or bicondylar, was associated with a higher rate of ligamentous and vascular injuries compared with non-HEVTP fracture patterns. They were also associated with worse health-related quality of life at midterm follow-up. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Technical Factors Contributing to Nonunion in Supracondylar Distal Femur Fractures Treated With Lateral Locked Plating: A Risk-Stratified Analysis.

OBJECTIVE: To identify technical factors associated with nonunion after operative treatment with lateral locked plating. DESIGN: Retrospective cohort study. SETTING: Ten Level I trauma centers. PATIENT SELECTION CRITERIA: Adult patients with supracondylar distal femur fractures (OTA/AO type 33A or C) treated with lateral locked plating from 2010 through 2019. OUTCOME MEASURES AND COMPARISONS: Surgery for nonunion stratified by risk for nonunion. RESULTS: The cohort included 615 patients with supracondylar distal femur fractures. The median patient age was 61 years old (interquartile range: 46 -72years) and 375 (61%) were female. Observed were nonunion rates of 2% in a low risk of nonunion group (n = 129), 4% in a medium-risk group (n = 333), and 14% in a high-risk group (n = 153). Varus malreduction with an anatomic lateral distal femoral angle greater than 84 degrees, was associated with double the odds of nonunion compared to those without such varus [odds ratio, 2.1; 95% confidence interval (CI), 1.1-4.2; P = 0.03]. Malreduction by medial translation of the articular block increased the odds of nonunion, with 30% increased odds per 4 mm of medial translation (95% CI, 1.0-1.6; P = 0.03). Working length increased the odds of nonunion in the medium risk group, with an 18% increase in nonunion per 10-mm increase in working length (95% CI, 1.0-1.4; P = 0.01). Increased proximal screw density was protective against nonunion (odds ratio, 0.71; 95% CI, 0.53-0.92; P = 0.02) but yielded lower mRUST scores with each 0.1 increase in screw density associated with a 0.4-point lower mRUST (95% CI, -0.55 to -0.15; P < 0.001). Lateral plate length and type of plate material were not associated with nonunion. ( P > 0.05). CONCLUSIONS: Malreduction is a surgeon-controlled variable associated with nonunion after lateral locked plating of supracondylar distal femur fractures. Longer working lengths were associated with nonunion, suggesting that bridge plating may be less likely to succeed for longer fractures. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Nail Plate Combination Fixation Versus Lateral Locked Plating for Distal Femur Fractures: A Multicenter Experience.

OBJECTIVES: To (1) report on clinical, radiographic, and functional outcomes after nail-plate fixation (NPF) of distal femur fractures and (2) compare outcomes after NPF with a propensity matched cohort of fractures treated with single precontoured lateral locking plates. DESIGN: Multicenter retrospective cohort study. SETTING: Ten Level 1 trauma centers. PATIENTS/PARTICIPANTS: Patients with OTA/AO 33A or 33C fractures. INTERVENTION: Fixation with (1) retrograde intramedullary nail combined with lateral locking plate (n = 33) or (2) single precontoured lateral locking plate alone (n = 867). MAIN OUTCOME MEASUREMENTS: The main outcomes of interest were all-cause unplanned reoperation and presence of varus collapse at final follow-up. RESULTS: One nail-plate patient underwent unplanned reoperation excluding infection and 2 underwent reoperation for infection at an average of 57 weeks after surgery. No nail-plate patients required unplanned reoperation to promote union and none exhibited varus collapse. More than 90% were ambulatory with no or minimal pain at final follow-up. In comparison, 7 of the 30 matched lateral locked plating patients underwent all-cause unplanned reoperation excluding infection (23% vs. 3%, P = 0.023), and an additional 3 lateral locked plating patients were found to have varus collapse on final radiographs (10% vs. 0%, P = 0.069). CONCLUSIONS: Despite a high proportion of high-energy, open, and comminuted fractures, no NPF patients underwent unplanned reoperation to promote union or demonstrated varus collapse. Propensity score matched analysis revealed significantly lower rates of nonunion for NPF compared with lateral locked plating alone. Larger studies are needed to identify which distal femur fracture patients would most benefit from NPF. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

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.

Medial and lateral dual plating of native distal femur fractures: a systematic literature review.

Introduction: Lateral locked plating (LLP) development has improved outcomes for distal femur fractures. However, there is still a modest rate of nonunion in fractures treated with LLP alone, with higher nonunion risk in high-energy fractures, intra-articular involvement, poor bone quality, severe comminution, or bone loss. Several recent studies have demonstrated both the safety and the biomechanical advantage of dual medial and lateral plating (DP). The purpose of this study was to evaluate the clinical outcomes of DP for native distal femoral fractures by performing a systematic review of the literature. Methods: Studies reporting clinical outcomes for DP of native distal femur fractures were identified and systematically reviewed. Publications without full-text manuscripts, those solely involving periprosthetic fractures, or fractures other than distal femur fractures were excluded. Fracture type, mean follow-up, open versus closed fracture, number of bone grafting procedures, nonunion, reoperation rates, and complication data were collected. Methodologic study quality was assessed using the Coleman methodology score. Results: The initial electronic review and reverse inclusion protocol identified 1484 publications. After removal of duplicates and abstract review to exclude studies that did not discuss clinical treatment of femur fractures with dual plating, 101 potential manuscripts were identified and manually reviewed. After final review, 12 studies were included in this study. There were 199 fractures with average follow-up time of 13.72 months. Unplanned reoperations and nonunion occurred in 19 (8.5%) and 9 (4.5%) cases, respectively. The most frequently reported complications were superficial infection (n = 6, 3%) and deep infection (n = 5, 2.5%) postoperatively. Other complications included delayed union (n = 6, 3%) not requiring additional surgical treatment and knee stiffness in four patients (2%) necessitating manipulation under anesthesia or lysis of adhesions. The average Coleman score was 50.5 (range 13.5-72), suggesting that included studies were of moderate-to-poor quality. Conclusions: Clinical research interest in DP of distal femoral fractures has markedly increased in the past few decades. The current data suggest that DP of native distal femoral fractures is associated with favorable nonunion and reoperation rates compared with previously published rates associated with LLP alone. In the current review, DP of distal femoral fractures was associated with acceptable rates of complications and generally good functional outcomes. More high-quality, directly comparable research is necessary to validate the conclusions of this review.

No Increased Risk of Nonunion with Bisphosphonate Use in a Medicare Claims Cohort Following Operatively Treated Long-Bone Fractures.

BACKGROUND: The diagnosis of a fragility fracture represents an important intervention event for the initiation of medical osteoporosis treatments. However, it is unclear if osteoporosis medications increase the risk of nonunion if administered in the setting of acute fracture. The purpose of the present study was to investigate whether bisphosphonates or selective estrogen receptor modulators/hormone replacement therapy (SERM/HRT) are associated with nonunion following fracture in a Medicare population. METHODS: A retrospective analysis of Medicare claims from 2016 to 2019 was performed to identify patients ≥65 years of age who had a surgically treated long-bone fracture as identified with Current Procedural Terminology (CPT) codes and International Classification of Diseases, 10th Revision (ICD-10) codes. Successive claims were linked for each beneficiary through 1 year following the fracture to determine fracture union status. Multivariable logistic regression models were specified to identify the association between medications and fracture union status while controlling for age, sex, race, Charlson Comorbidity Index (CCI), and fracture type. RESULTS: Of the 111,343 included fractures, 10,452 (9.4%) were associated with a diagnosis of nonunion within 1 year. The nonunion group was younger (79.8 ± 8.3 versus 80.6 ± 8.4 years; p < 0.001), more likely to be White (92.4% versus 90.9%; p < 0.001), and more likely to have a CCI of ≥2 (50.9% versus 49.4%; p < 0.001). Bisphosphonate use was more common in the nonunion group (12.2% versus 11.4%; p = 0.017). When controlling for race, age, sex, and CCI, neither bisphosphonates (OR, 1.06 [95% CI, 0.99 to 1.12]; p = 0.101) nor SERM/HRT (OR, 1.13 [0.93 to 1.36]; p = 0.218) were associated with nonunion. Bisphosphonate use within 90 days post-fracture was not significantly associated with nonunion (OR, 0.94 [95% CI, 0.86 to 1.03]; p = 0.175), and the timing of medication administration did not influence fracture union status. CONCLUSIONS: The rate of nonunion after operatively treated long-bone fractures was 9.4%. In this cohort, use of a bisphosphonate or SERM/HRT was not associated with fracture union status at 1 year. Orthopaedic surgeons should not withhold or delay initiating medical therapies for osteoporosis in the setting of acute fracture out of concern for nonunion. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Induced Membrane Technique Is Effective for the Management of Acute Traumatic Bone Loss in Both Diaphyseal and Metaphyseal Lower Extremity Fractures.

OBJECTIVE: To compare outcomes of Masquelet-induced membrane technique (IMT) in metaphyseal and diaphyseal fractures with acute bone loss. DESIGN: Retrospective cohort study. SETTING: Four Level 1 Academic Trauma Centers. PATIENTS/PARTICIPANTS: Patients acutely treated with IMT for traumatic lower extremity bone loss at 4 Level 1 trauma centers between 2010 and 2020. INTERVENTION: Operative treatment with placement of cement spacer within 3 weeks of initial injury followed by staged removal and bone grafting to the defect. MAIN OUTCOME MEASUREMENTS: Fracture union, infection, revision grafting, time to union, and amputation. RESULTS: One hundred twenty fractures met inclusion criteria, including 43 diaphyseal fractures (DIM) and 77 metaphyseal fractures (MIM). Demographic characteristics were not significantly different, except for age (DIM 34 years vs. MIM 43 years, P < 0.001). Union after treatment with IMT was 89.2% overall. After controlling for age, this was not significantly different between DIM (41/43, 95.3%) and MIM (66/77, 85.7%) ( P = 0.13) nor was the rate of infection between groups. There was no difference in any secondary outcomes. CONCLUSIONS: The overall union rate in the current series of acute lower extremity fractures treated with the induced membrane technique was 89%. There was no difference in successful union between patients with diaphyseal bone loss or metaphyseal bone loss treated with IMT. Similarly, there was no difference in patients with tibial or femoral bone loss treated with induced membrane. Defect size after debridement may be more prognostic for secondary operations rather than the limb segment involved or the degree of soft-tissue injury. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Butterfly fragments in diaphyseal tibial fractures heal unpredictably: Should we be adopting other strategies for these high risk fractures?

INTRODUCTION: The natural history of diaphyseal tibial butterfly fragments is poorly documented. Numerous studies have analyzed risk factors for nonunions in the tibial shaft with known factors including Gustilo classification, ASA class, and cortical contact. However, the healing potential and ideal management of nonsegmental butterfly fragments in this setting remains unknown. The aim of this study was to determine the nonunion rate of diaphyseal tibial fractures with a butterfly fragment. METHODS: A performed a retrospective review of patients at a single academic Level 1 Trauma Center from 2000-2020 who underwent intramedullary nailing of tibial shaft fractures. Those with non-segmental butterfly fragments (OTA/AO: 42-B) and minimum 12 month follow up were included. Morphologic measurements of butterfly fragments were performed to measure location, size, and displacement, and mRust scores at final follow up were calculated. Outcome measures were surgery to promote union, and mRust scores. RESULTS: A total of 99 patients were included with 21 patients requiring revision surgery to promote union. Thirty six patients had open fractures and 77% of patients were male with a mean age of 34 (range: 12-80). Average follow up was 19 months (3 months - 12 years). The most common location of the butterfly fragment was the anterior cortex (42%), with a mean length of 7.8cm (SD: 3.3) and width of 1.8cm (SD: 0.5cm). At final follow-up 37% of fractures had persistent lucency without callus at the site of the butterfly while only 31% of fractures had remodeled cortex. Average time to complete healing was 13.3 months. Open fractures with butterfly fragments were more likely to go on to nonunion than closed (44% vs 9.2%, p=<0.001). The length of the butterfly fragment was not different between the union and nonunion groups (7.7 vs 7.5, P=0.42). CONCLUSIONS: Open tibial shaft fractures with a butterfly fragment have a high risk of nonunion. Further research may seek to determine if adjunct treatment of butterfly fragments (ie inter-fragmentary compression) in the acute setting could improve healing rates.

Predictors of Deep Infection After Distal Femur Fracture: A Multicenter Study.

OBJECTIVES: To identify potentially modifiable risk factors for deep surgical site infection after distal femur fracture. DESIGN: Multicenter retrospective cohort study. SETTING: Ten Level-I trauma centers. PATIENTS/PARTICIPANTS: Patients with OTA/AO 33A or C distal femur fractures (n = 1107). INTERVENTION: Surgical fixation of distal femur fracture. MAIN OUTCOME MEASUREMENT: The outcome of interest was deep surgical site infection. RESULTS: There was a 7% rate (79/1107) of deep surgical site infection. In the multivariate analysis, predictive factors included alcohol abuse [odds ratio (OR) = 2.36; 95% confidence interval (CI), 1.17-4.46; P = 0.01], intra-articular injury (OR = 1.73; 95% CI, 1.01-3.00; P = 0.05), vascular injury (OR = 3.90; 95% CI, 1.63-8.61; P < 0.01), the use of topical antibiotics (OR = 0.50; 95% CI, 0.25-0.92; P = 0.03), and the duration of the surgery (OR = 1.15 per hour; 95% CI, 1.01-1.30; P = 0.04). There was a nonsignificant trend toward an association between infection and type III open fracture (OR = 1.73; 95% CI, 0.94-3.13; P = 0.07) and lateral approach (OR = 1.60; 95% CI, 0.95-2.69; P = 0.07). The most frequently cultured organisms were methicillin-resistant Staphylococcus aureus (22%), methicillin-sensitive Staphylococcus aureus (20%), and Enterobacter cloacae (11%). CONCLUSIONS: Seven percent of distal femur fractures developed deep surgical site infections. Alcohol abuse, intra-articular fracture, vascular injury, and increased surgical duration were risk factors, while the use of topical antibiotics was protective. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Risk Factors for Reoperation to Promote Union in 1111 Distal Femur Fractures.

OBJECTIVES: To identify modifiable and nonmodifiable risk factors for reoperation to promote union after distal femur fracture. DESIGN: Multicenter retrospective cohort study. SETTING: Ten Level-I trauma centers. PATIENTS/PARTICIPANTS: Patients with OTA/AO 33A or C distal femur fractures (n = 1111). INTERVENTION: Surgical fixation of distal femur fracture. Fixation constructs were classified as lateral plate, dual plate, nail, or nail plate combination. MAIN OUTCOME MEASUREMENTS: The outcome of interest was unplanned reoperation to promote union. RESULTS: There was an 11% (121/1111) rate of unplanned reoperation to promote union. In the multivariate analysis, predictive factors included body mass index [odds ratio (OR) = 1.18; 95% confidence interval (CI), 1.06-1.32; P < 0.01], intra-articular fracture (OR = 1.57; 95% CI, 1.01-2.45; P = 0.04), type III open injury (OR = 2.29; 95% CI, 1.41-3.72; P < 0.01), the presence of medial comminution (OR = 1.85; 95% CI, 1.14-3.06; P = 0.01), and medial translation on postoperative radiographs (OR = 1.23 per one 10th of condylar width; 95% CI, 1.01-1.48; P = 0.03). Construct type was not significantly predictive. CONCLUSIONS: Eleven percent of distal femur fractures underwent unplanned reoperation to promote union. Body mass index, intra-articular fracture, type III open injury, medial comminution, and medial translation on postoperative radiographs were predictive factors. Construct type was not associated with unplanned reoperation; however, this conclusion was limited by small numbers in the dual plate and nail plate groups. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Reformatting of Computed Tomography Scans Parallel to the S1 End Plate Increases Visualization of Trans Sacral Pathway in the First Sacral Segment, Especially With Dysmorphism.

OBJECTIVE: To determine whether reformatted computed tomography (CT) scans would increase surgeons' confidence in placing a trans sacral (TS) screw in the first sacral segment. SETTING: Level 1 trauma center. DESIGN: A retrospective cohort study. PATIENTS/PARTICIPANTS: There were 50 patients with uninjured pelvises who were reviewed by 9 orthopaedic trauma fellowship-trained surgeons and 5 orthopaedic residents. MAIN OUTCOME MEASUREMENTS: The overall percentage of surgeons who believe it was safe to place a TS screw in the first sacral segment with standard (axial cuts perpendicular to the scanner gantry) versus reformatted (parallel to the S1 end plate) CT scans. RESULTS: Overall, 58% of patients were believed to have a safe corridor in traditional cut axial CT scans, whereas 68% were believed to have a safe corridor on reformatted CT scans ( P < 0.001). When grouped by dysplasia, those without sacral dysplasia (n = 28) had a safe corridor 93% of the time on traditional scans and 93% of the time with reformatted CT scans ( P = 0.87). However, of those who had dysplasia (n = 22), only 12% were believed to have a safe corridor on original scans compared with 35% on reformatted scans ( P < 0.001). CONCLUSIONS: CT scan reformatting parallel to the S1 superior end plate increases the likelihood of identifying a safe corridor for a TS screw, especially in patients with evidence of sacral dysplasia. The authors would recommend the routine use of reformatting CT scans in this manner to provide a better understanding of the upper sacral segment osseous fixation pathways.

Wnt/ß-catenin-signaling and the formation of Müller glia-derived progenitors in the chick retina.

Müller glia can be stimulated to de-differentiate, proliferate, and form Müller glia-derived progenitor cells (MGPCs) that are capable of producing retinal neurons. The signaling pathways that influence the de-differentiation of mature Müller glia and proliferation of MGPCs may include the Wnt-pathway. The purpose of this study was to investigate how Wnt-signaling influences the formation of MGPCs in the chick retina in vivo. In NMDA-damaged retinas where MGPCs are known to form, we find dynamic changes in retinal levels of potential readouts of Wnt-signaling, including dkk1, dkk3, axin2, c-myc, tcf-1, and cd44. We find accumulations of nuclear ß-catenin in MGPCs that peaks at 3 days and rapidly declines by 5 days after NMDA-treatment. Inhibition of Wnt-signaling with XAV939 in damaged retinas suppressed the formation of MGPCs, increased expression of ascl1a and decreased hes5, but had no effect upon the differentiation of progeny produced by MGPCs. Activation of Wnt-signaling, with GSK3ß-inhibitors, in the absence of retinal damage, failed to stimulate the formation of MGPCs, whereas activation of Wnt-signaling in damaged retinas stimulated the formation of MGPCs. In the absence of retinal damage, FGF2/MAPK-signaling stimulated the formation of MGPCs by activating a signaling network that includes Wnt/ß-catenin. In FGF2-treated retinas, inhibition of Wnt-signaling reduced numbers of proliferating MGPCs, whereas activation of Wnt-signaling failed to influence the formation of proliferating MGPCs. Our findings indicate that Wnt-signaling is part of a network initiated by FGF2/MAPK or retinal damage, and activation of canonical Wnt-signaling is required for the formation of proliferating MGPCs. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 983-1002, 2016.