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).

METHODS

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.

Resident Synovial Macrophages in Synovial Fluid: Implications for Immunoregulation in Infectious and Inflammatory Arthritis

Objectives

Resident synovial macrophages (RSM) provide immune sequestration of the joint space and are likely involved in initiation and perpetuation of the joint-specific immune response. We sought to identify RSM in synovial fluid (SF) and demonstrate migratory ability, in additional to functional changes that may perpetuate a chronic inflammatory response within joint spaces.

Methods

We recruited human patients presenting with undifferentiated arthritis in multiple clinical settings. We used flow cytometry to identify mononuclear cells in peripheral blood and SF. We used a novel transwell migration assay with human ex-vivo synovium obtained intra-operatively to validate flow cytometry findings. We used single cell RNA-sequencing (scRNA-seq) to further identify macrophage/monocyte subsets. ELISA was used to evaluate the bone-resorption potential of SF.

Results

We were able to identify a rare population of CD14dim, OPG+, ZO-1+ cells consistent with RSM in SF via flow cytometry. These cells were relatively enriched in the SF during infectious processes, but absolutely decreased compared to healthy controls. Similar putative RSM were identified using ex vivo migration assays when MCP-1 and LPS were used as migratory stimulus. scRNA-seq revealed a population consistent with RSM transcriptionally related to CD56+ cytotoxic dendritic cells and IDO+ M2 macrophages.

Conclusion

We identified a rare cell population consistent with RSM, indicating these cells are likely migratory and able to initiate or coordinate both acute (septic) or chronic (autoimmune or inflammatory) arthritis. RSM analysis via scRNA-seq indicated these cells are M2 skewed, capable of antigen presentation, and have consistent functions in both septic and inflammatory arthritis.

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.

METHODS

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.

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.

Do Pediatric Hospitals Improve Operative Efficiency?

BACKGROUND

In recent years there has been a push towards developing free standing pediatric facilities to provide care specifically towards pediatric patients. The purpose of this study was to determine if moving pediatric cases from a general hospital to a dedicated pediatric facility improved the quality and efficiency of surgical procedures.

METHODS

A retrospective review of pediatric patients undergoing posterior spinal fusion (PSF) was performed. All procedures were performed by one orthopaedic surgeon (SLW) from 2015 to 2019. The procedures were performed at a general hospital (GH) the first two years, and at a pediatric hospital (PH) the subsequent years. Data extracted included patient sex, age, and procedure type as well as procedure duration, operative turnover time, hospital length of stay, transfusion requirements, and operative delay. Exclusively pediatric adolescent idiopathic scoliosis (AIS) patients undergoing PSF were included due to the high volume and consistent surgical procedures therefore limiting confounding variables.

RESULTS

A total of five hundred PSF pediatric procedures were performed during the time period. After excluding non-adolescent idiopathic scoliosis cases, a total of 208 procedures were reviewed (105 at GH; 103 at PH). There was no statistical difference between the groups in regards to operative time (GH: 200 min, PH: 200 min; p=0.91), room turnover time (GH: 38 min, PH: 38 min; p=0.801), or rate of transfusion (GH: 20% PH: 30%; p=0.09). Length of stay was significantly shorter in the PH cohort compared to the GH cohort (4.35 vs. 3.84 days, p=0.0001). However, a smaller proportion of cases at the PH started on time compared to the GH (34% vs. 58%; p=0.0005).

CONCLUSION

Overall, this study demonstrated that AIS procedures at the PH did show a statistically significant reduction in hospital length of stay. However, timely start of the procedure was less likely at this particular facility. Level of Evidence: III.

Low-energy Gunshot-induced Tibia Fractures: What Proportion Develop Complications?

BACKGROUND

Gunshot injuries of the extremities are common in the United States, especially among people with nonfatal gunshot wounds. Controversy persists regarding the proper management for low-energy gunshot-induced fractures, likely stemming from varying reports on the likelihood of complications. There has yet to be published a study on a large cohort of patients with gunshot-induced tibia fractures on which to base our understanding of complications after this injury.

QUESTIONS/PURPOSES

(1) What percentage of patients with low-energy gunshot-induced tibia fractures developed complications? (2) Was there an association between deep infection and fracture location, injury characteristics, debridement practices, or antibiotic use?

METHODS

This was a multicenter retrospective study. Between January 2009 and December 2018, we saw 201 patients aged 16 years or older with a gunshot-induced fracture who underwent operative treatment; 2% (4 of 201) of those screened had inadequate clinical records, and 38% (76 of 201) of those screened had inadequate follow-up for inclusion. In all, 121 patients with more than 90 days of follow-up were included in the study. Nonunion was defined as a painful fracture with inadequate healing (fewer than three cortices of bridging bone) at 6 months after injury, resulting in revision surgery to achieve union. Deep infection was defined according to the confirmatory criteria of the Fracture-Related Infection Consensus Group. These results were assessed by a fellowship-trained orthopaedic trauma surgeon involved with the study. Complication proportions were tabulated. A Kaplan-Meier chart demonstrated presentations of deep infection by fracture location (proximal, shaft, or distal). Univariate statistics and multivariate Cox regression were used to examine the association between deep infection and fracture location, entry wound size, vascular injury, intravenous (IV) antibiotics in the emergency department (ED), deep and superficial debridement, the duration of postoperative IV antibiotics, and the use of topical antibiotics, while adjusting for age, race/ethnicity, smoking status, and BMI. A power analysis for the result of deep infection demonstrated that we would have had to observe a hazard ratio of 4.28 or greater for shaft versus proximal locations to detect statistically significant results at 80% power and alpha = 0.05.

RESULTS

The overall complication proportion was 49% (59 of 121), with proportions of 14% (17 of 121) for infection, 27% (33 of 121) for wound complications, 20% (24 of 121) for nonunion, 9% (11 of 121) for hardware breakage, and 26% (31 of 121) for revision surgery. A positive association was present between deep infection and deep debridement (HR 5.51 [95% confidence interval 1.12 to 27.9]; p = 0.04). With the numbers available, we found no association between deep infection and fracture location, entry wound size, vascular injury, IV antibiotics in the ED, superficial debridement, the duration of postoperative IV antibiotics, and the use of topical antibiotics.

CONCLUSION

In this multicenter study, we found a higher risk of complications in operative gunshot-induced tibia fractures than prior studies have reported. Infection, in particular, was much more common than expected based on prior studies. Consequently, surgeons might consider adopting the general management principles for nongunshot-induced open tibia fractures with gunshot-induced fractures, such as the use of IV antibiotics both initially and after surgery. Further research is needed to test and validate these approaches.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Preoperative Opioid Usage, Male Sex, and Preexisting Knee Osteoarthritis Impacts Opioid Refills After Isolated Arthroscopic Meniscectomy: A Population-Based Study

PURPOSE

To identify risk factors for opioid consumption after arthroscopic meniscectomy using a large national database.

METHODS

Patients undergoing primary arthroscopic meniscectomy from 2007 to 2016 were retrospectively accessed from the Humana database. Patients were categorized as those who filled opioid prescriptions within 3 months (OU), within 1 month (A-OU), between 1 and 3 months (C-OU), and never filled opioid prescriptions (N-OU) before surgery. Rates of opioid use were evaluated preoperatively and longitudinally tracked for each cohort. Prolonged opioid use was defined as continued opioid prescription filling at ≥3 months after surgery. Multiple logistic regression analysis was used to identify factors associated with opioid refills at 12 months after surgery.

RESULTS

There were 88,120 patients (53.7% female) who underwent arthroscopic meniscectomy, of whom 46.1% (n = 39,078) were N-OU. About a quarter (25.3%) of patients continued filling opioid prescriptions at 1 year postoperatively. In addition, opioid fill rate at 1 year was significantly greater in the OU group compared with the N-OU group with a relative risk of 2.89 (40.7% vs 14.1%; 95% confidence interval 2.81-2.98; P < .0001). Multiple logistic regression model identified C-OU (odds ratio 3.67; 95% confidence interval 3.53-3.82; P < .0001) as the strongest predictor of opioid use at 12 months postoperatively. Furthermore, male sex, A-OU, knee osteoarthritis, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, fibromyalgia, anxiety or depression, alcohol use disorder, and tobacco use (P < .02 for all) had significantly increased odds of opioid use at 12 months postoperatively. However, patients <40 years (P < .0001) had significantly decreased odds of opioid use 12 months postoperatively.

CONCLUSIONS

Preoperative opioid filling is a significant risk factor for opioid use at 12 months postoperatively. Male sex, preexisting knee osteoarthritis, and diagnosis of anxiety or depression were independent risk factors for opioid use 12 months following arthroscopic meniscectomy.

LEVEL OF EVIDENCE

Level-III, Retrospective Cohort Study.

The effects of season and sex on dentate gyrus size and neurogenesis in a wild rodent, Richardson's ground squirrel (Urocitellus richardsonii)

Sex and reproductive status affect hippocampal neurogenesis and dentate gyrus (DG) size in rodents. Relatively few studies, however, address these two effects simultaneously and even fewer studies address this issue in wild populations. Here, we examined seasonal and sex differences in neurogenesis and DG size in a wild, polygynous and social rodent, Richardson's ground squirrel (Uriocitellus richardsonii). Based on the behavioral ecology of this species, we predicted that both neurogenesis and DG size would be sexually dimorphic and the degree of dimorphism would be greatest in the breeding season. Using unbiased stereology and doublecortin (DCX) immunohistochemistry, we found that brain volume, DG size and number of DCX cells varied significantly between breeding and non-breeding seasons, but only brain volume and the number of DCX labeled cells differed between the sexes. Both sex and seasonal differences likely reflect circulating hormone levels, but the extent to which these differences relate to space use in this species is unclear. Based on the degree of seasonal differences in neurogenesis and the DG, we suggest that ground squirrels could be considered model species in which to examine hippocampal plasticity in an ecologically valid context.