RESUMO
OBJECTIVES: To evaluate radiographic and clinical patient reported clinical outcomes following dorsal hook plating of displaced patella fractures with permittance of immediate post-operative active closed chain range of motion. DESIGN: Retrospective review of prospectively collected data. SETTING: Urban Academic Level 1 Trauma Center. PATIENT SELECTION CRITERIA: Adult patients with displaced patella fractures (OTA/AO 34C1-3) who underwent dorsal plating with immediate range of motion between 2018-2023. OUTCOME MEASURES AND COMPARISONS: Numerical Rating Scale for Pain, Knee Outcome Score (KOS-ADL), Tegner-Lysholm Score, radiographic union, and wound complications were collected. RESULTS: 61 patients were included (47 female) with an average age of 63 years (SD 14.7, range 22-86 years). The mean BMI was 24.2 (SD 3.6, range 16.6-33.3). There were thirteen 34-C2 and forty-eight 34-C3 fractures. All but 2 patients (96.7%) achieved bony union after the index procedure. 89% (n=54) of patients completed outcome surveys with at least 6 months follow-up. Six patients (9.8%) underwent removal of plate implant at a mean of 15.1 months post-operatively. The mean KOS-ADL score was 91.4, the mean Tegner-Lysholm score was 78.1, and the mean NRS was 2.7. CONCLUSION: Dorsal hook plating offers secure fixation to allow early range of motion, reliable fixation with low non-union and implant failure rates, low implant removal rates, and satisfactory patient reported outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
RESUMO
Persistent infection by Staphylococcus aureus has been linked to the bacterial stringent response (SR), a conserved stress response pathway regulated by the Rel protein. Rel synthesizes (p)ppGpp "alarmones" in response to amino acid starvation, which enables adaptation to stress by modulating bacterial growth and virulence. We previously identified five novel protein-altering mutations in rel that arose in patients with persistent methicillin-resistant S. aureus bacteremia. The mutations mapped to both the enzymatic and regulatory protein domains of Rel. Here, we set out to characterize the phenotype of these mutations to understand how they may have been selected in vivo. After introducing each mutation into S. aureus strain JE2, we analyzed growth, fitness, and antibiotic profiles. Despite being located in different protein domains, we found that all of the mutations converged on the same phenotype. Each shortened the time of lag phase growth and imparted a fitness advantage in nutritionally depleted conditions. Through quantification of intracellular (p)ppGpp, we link this phenotype to increased SR activation, specifically during the stationary phase of growth. In contrast to two previously identified clinical rel mutations, we find that our rel mutations do not cause antibiotic tolerance. Instead, our findings suggest that in vivo selection was due to an augmented SR that primes cells for growth in nutrient-poor conditions, which may be a strategy for evading host-imposed nutritional immunity. Importance Host and pathogen compete for available nutrition during infection. For bacteria, the stringent response (SR) regulator Rel responds to amino acid deprivation by signaling the cell to modulate its growth rate, metabolism, and virulence. In this report, we characterize five rel mutations that arose during cases of persistent methicillin-resistant Staphylococcus aureus bacteremia. We find that all of the mutations augmented SR signaling specifically under nutrient-poor conditions, enabling the cell to more readily grow and survive. Our findings reveal a strategy used by bacterial pathogens to evade the nutritional immunity imposed by host tissues during infection.
