Complications of periprosthetic fracture revision vs aseptic revision of total knee arthroplasty.

Background: Periprosthetic fractures after total knee arthroplasty (TKA) are a challenging problem due to complex fracture patterns, poor bone quality, and a high-risk patient population. Treatment of both periprosthetic fractures and aseptic complications can include revision TKA. In this study, we compared systemic and orthopaedic complications following periprosthetic fracture associated revision TKA to aseptic revision TKA. Methods: This is a retrospective cohort study using data from the years 2010-2020 from a national administrative claims database. Billing codes were used to identify revision TKAs with a diagnosis of periprosthetic fracture or aseptic complications (loosening, dislocation, arthrofibrosis, osteolysis, or prosthetic wear) within one year prior to revision. Pertinent systemic complications and rates of repeat revision TKA, periprosthetic infection, and repeat fractures were compared between the two groups. Results: We identified 9891 periprosthetic fracture associated revision TKAs and 47,071 aseptic revision TKAs. Our study found higher rate of systemic complications including AKI, DVT, wound disruption, hematoma, and surgical site infections in periprosthetic fracture associated revision TKA compared to aseptic revision TKA. Furthermore, we found higher rates of repeat revision TKA, periprosthetic infections, and repeat periprosthetic fractures in fracture associated revision TKA group compared to aseptic revision group. Conclusions: Our work highlights the significant short- and long-term complications associated with periprosthetic fracture associated revision TKA. Future working comparing functional outcomes and optimal surgical techniques are needed.

Outcomes of Surgically Treated Pilon Fractures: A Comparison of Patients with and without Diabetes.

OBJECTIVES: Compare systemic complications, fracture healing related complications, and reoperation rates for pilon fractures in patients with and without diabetes. DESIGN: Retrospective cohort study. SETTING: National administrative claims database with patient records. PATIENTS: Patients from the years 2016 to 2020 with surgically treated closed or open pilon fractures. INTERVENTION: Patients with either closed or open pilon fractures with diabetes were compared to those without diabetes. Subgroup analysis was performed on diabetic patients with and without neuropathy. OUTCOMES: Postoperative systemic complications at 90 days, fracture healing complications at 90 days and 1 year, and reoperative rates at 90 days and 1 year. RESULTS: 2,654 (31.4%) patients with closed fractures and 491 (28.7%) patients with open fractures had a diagnosis of diabetes. In both open and closed fractures, we identified significantly higher rates of acute kidney injury, cardiac arrest, and surgical site infection in diabetic patients compared to non-diabetic patients. Additionally, we found significantly higher rates of below knee amputations in diabetic patients. Diabetic patients with closed fractures had significantly higher rates of wound healing related reoperations. Patients with advanced diabetic disease, as suggested by the presence of neuropathy, had higher rates of nonunions and post-traumatic arthritis. CONCLUSIONS: The data presented here provides updated estimates on complication rates in pilon fractures using large sample size. Additionally, our work identifies differences in outcomes for patients with and without diabetes following pilon fracture surgery. Our data suggests that patients with severe diabetes are prone to higher rates of healing complications and may benefit from additional therapeutic support. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Analysis of inpatient complications in HIV/AIDS patients undergoing total hip arthroplasty - A propensity matched cohort study.

Patients with human immunodeficiency virus (HIV) are at higher risk for orthopedic related diseases due to dysregulation in bone metabolism and metabolic effects related to their medication regimen. Furthermore, the rate of hip arthroplasty in HIV patients is increasing. With the recent changes in THA methodologies and improvements in HIV treatment, there is a need for updated research analyzing hip arthroplasty outcomes in this high-risk patient population. In this study, we used a national database to evaluate postoperative outcomes in HIV patients undergoing THA compared to THA patients without HIV. We use a propensity algorithm to create a cohort of 493 HIV negative patients for matched analysis. Among the 367,894 THA patients included in this study, 367,390 patients were HIV negative and 504 were HIV positive. The HIV cohort had a lower mean age (53.34 vs 65.88, p < 0.001), lower proportion of females (44% vs 76.4%, p < 0.001), lower incidence of diabetes without complications (5% vs 11.1%, p < 0.001) and a lower incidence of obesity (0.544 vs 0.875, p = 0.002). In the unmatched analysis, the incidence of acute kidney injury (4.8% vs 2.5%, p = 0.004), pneumonia (1.2% vs 0.2%, p = 0.002), periprosthetic infection (3.6% vs 1%, p < 0.001), and wound dehiscence (0.6% vs 0.1%, p = 0.009) were higher in HIV cohort, most likely due to inherent demographic variances present in the HIV population. In the matched analysis, the rates of blood transfusion (5.0% vs 8.3%, p = 0.041) were lower in the HIV cohort. Other post-operative variables, such as rates of pneumonia, wound dehiscence, and surgical site infections were not statistically significant between the HIV positive population and HIV negative matched cohort. Our study found similar rates of postoperative complications in HIV positive and HIV negative patients. The rate of blood transfusions in HIV positive patients was also noted to be lower. Our data suggests that THA is a safe procedure in patients infected with HIV.

Postoperative complications of spinal vs general anesthesia in elderly patients undergoing hip hemiarthroplasty.

INTRODUCTION: Elderly patients with hip fractures are at high risk for mortality due to postsurgical complications. Hip hemiarthroplasty is a routine procedure done in elderly patients for surgical repair  of femoral neck fractures. Both general and spinal anesthesia can be used in elderly patients undergoing hemiarthroplasty. Rates of postoperative complications among the two anesthetic choices have not been directly compared. In this study, we compare the rates of postoperative complications in elderly patients (age greater than 70) undergoing hip hemiarthroplasty for femoral neck fractures using a national database. METHODS: Data for the years 2015-2020 from the National Surgical Quality Improvement Program (NSQIP) were used for the study. Patients greater than 70 years of age who received a hip hemiarthroplasty with general anesthesia or spinal anesthesia were identified using CPT procedure codes. Pertinent preoperative variables and rates of postoperative complications were characterized and analyzed. RESULTS: Our study found that elderly patients who received spinal anesthesia had, on average, longer length of stays but shorter operative times compared to patients who received general anesthesia. Furthermore, we found that patients who received spinal anesthesia had lower rates of systemic sepsis, cardiac arrests, and blood transfusions when compared to patients who received general anesthesia. Finally, we found that overall rates of mortality were significantly lower in the spinal anesthesia cohort compared to the general anesthesia cohort. CONCLUSION: Our work suggests that patients who underwent spinal anesthesia for hip arthroplasty may have lower rates of postoperative complications. This work further highlights the role of anesthetic choice in preventing complications following hip hemiarthroplasty procedures.

Macrophage-mediated PDGF Activation Correlates With Regenerative Outcomes Following Musculoskeletal Trauma.

OBJECTIVE: Our objective was to identify macrophage subpopulations and gene signatures associated with regenerative or fibrotic healing across different musculoskeletal injury types. BACKGROUND: Subpopulations of macrophages are hypothesized to fine tune the immune response after damage, promoting either normal regenerative, or aberrant fibrotic healing. METHODS: Mouse single-cell RNA sequencing data before and after injury were assembled from models of musculoskeletal injury, including regenerative and fibrotic mouse volumetric muscle loss (VML), regenerative digit tip amputation, and fibrotic heterotopic ossification. R packages Harmony , MacSpectrum , and Seurat were used for data integration, analysis, and visualizations. RESULTS: There was a substantial overlap between macrophages from the regenerative VML (2 mm injury) and regenerative bone models, as well as a separate overlap between the fibrotic VML (3 mm injury) and fibrotic bone (heterotopic ossification) models. We identified 2 fibrotic-like (FL 1 and FL 2) along with 3 regenerative-like (RL 1, RL 2, and RL 3) subpopulations of macrophages, each of which was transcriptionally distinct. We found that regenerative and fibrotic conditions had similar compositions of proinflammatory and anti-inflammatory macrophages, suggesting that macrophage polarization state did not correlate with healing outcomes. Receptor/ligand analysis of macrophage-to-mesenchymal progenitor cell crosstalk showed enhanced transforming growth factor ß in fibrotic conditions and enhanced platelet-derived growth factor signaling in regenerative conditions. CONCLUSION: Characterization of macrophage subtypes could be used to predict fibrotic responses following injury and provide a therapeutic target to tune the healing microenvironment towards more regenerative conditions.

Single-cell mapping of regenerative and fibrotic healing responses after musculoskeletal injury.

After injury, a cascade of events repairs the damaged tissue, including expansion and differentiation of the progenitor pool and redeposition of matrix. To guide future wound regeneration strategies, we compared single-cell sequencing of regenerative (third phalangeal element [P3]) and fibrotic (second phalangeal element [P2]) digit tip amputation (DTA) models as well as traumatic heterotopic ossification (HO; aberrant). Analyses point to a common initial response to injury, including expansion of progenitors, redeposition of matrix, and activation of transforming growth factor ß (TGF-ß) and WNT pathways. Surprisingly, fibrotic P2 DTA showed greater transcriptional similarity to HO than to regenerative P3 DTA, suggesting that gene expression more strongly correlates with healing outcome than with injury type or cell origin. Differential analysis and immunostaining revealed altered activation of inflammatory pathways, such as the complement pathway, in the progenitor cells. These data suggests that common pathways are activated in response to damage but are fine tuned within each injury. Modulating these pathways may shift the balance toward regenerative outcomes.

Contemporary perspectives on heterotopic ossification.

Heterotopic ossification (HO) is the formation of ectopic bone that is primarily genetically driven (fibrodysplasia ossificans progressiva [FOP]) or acquired in the setting of trauma (tHO). HO has undergone intense investigation, especially over the last 50 years, as awareness has increased around improving clinical technologies and incidence, such as with ongoing wartime conflicts. Current treatments for tHO and FOP remain prophylactic and include NSAIDs and glucocorticoids, respectively, whereas other proposed therapeutic modalities exhibit prohibitive risk profiles. Contemporary studies have elucidated mechanisms behind tHO and FOP and have described new distinct niches independent of inflammation that regulate ectopic bone formation. These investigations have propagated a paradigm shift in the approach to treatment and management of a historically difficult surgical problem, with ongoing clinical trials and promising new targets.