Investigating the effect of autograft diameter for quadriceps and patellar tendons use in anterior cruciate ligament reconstruction: a biomechanical analysis using a simulated Lachman test.

Introduction: Current clinical practice suggests using patellar and quadriceps tendon autografts with a 10 mm diameter for ACL reconstruction. This can be problematic for patients with smaller body frames. Our study objective was to determine the minimum diameter required for these grafts. We hypothesize that given the strength and stiffness of these respective tissues, they can withstand a significant decrease in diameter before demonstrating mechanical strength unviable for recreating the knee's stability. Methods: We created a finite element model of the human knee with boundary conditions characteristic of the Lachman test, a passive accessory movement test of the knee performed to identify the integrity of the anterior cruciate ligament (ACL). The Mechanical properties of the model's grafts were directly obtained from cadaveric testing and the literature. Our model estimated the forces required to displace the tibia from the femur with varying graft diameters. Results: The 7 mm diameter patellar and quadriceps tendon grafts could withstand 55-60 N of force before induced tibial displacement. However, grafts of 5.34- and 3.76-mm diameters could only withstand upwards of 47 N and 40 N, respectively. Additionally, at a graft diameter of 3.76 mm, the patellar tendon experienced 234% greater stiffness than the quadriceps tendon, with similar excesses of stiffness demonstrated for the 5.34- and 7-mm diameter grafts. Conclusions: The patellar tendon provided a stronger graft for knee reconstruction at all diameter sizes. Additionally, it experienced higher maximum stress, meaning it dissociates force better across the graft than the quadriceps tendon. Significantly lower amounts of force were required to displace the tibia for the patellar and quadriceps tendon grafts at 3.76- and 5.34-mm graft diameters. Based on this point, we conclude that grafts below the 7 mm diameter have a higher chance of failure regardless of graft selection.

eConsults' Impact on Care Access and Wait Times in Rheumatology.

BACKGROUND/OBJECTIVE: A growing number of health systems have implemented eConsults to improve access to specialty advice, but few studies have described their use in rheumatology or impact on visit wait times. We evaluated the uptake of an eConsult program and its impact on wait times for in-person rheumatology visits. METHODS: In this quality improvement project, we analyzed electronic health record data from 4 intervention clinics and 4 comparison clinics, 12 months before and after implementation of an eConsult program. We compared median wait time for rheumatology appointments using a pre-post difference-in-differences analysis and quantile regression, adjusting for patient age, race, sex, clinic pair, and primary insurance payer. We also interviewed 11 primary care providers from the intervention clinics and conducted a rheumatology provider focus group (n = 4) to elucidate experiences with the program. RESULTS: Rheumatologists recommended management in primary care or referral to another specialty for 41% of eConsults, reducing initial demand for in-person visits. The median wait times dropped in the intervention and the comparison clinics (42 and 25 days, respectively). Intervention clinic median wait time dropped 17 days more than comparison clinics, and this was nonstatistically significant (p = 0.089). eConsults fit provider care tasks best for triage or initial workup for diagnosis, and less well when tests required interpretation, or when back and forth communication was needed to manage the patient's condition. CONCLUSIONS: Implementation of eConsults for rheumatology was associated with reduced wait times for rheumatology appointments and supported primary care providers in the triage and workup for a substantial portion of patients.