Poster 245: Clinical Measurement of the Standard Q-Angle Correlates Poorly with Tibial Tuberosity to Trochlear Groove Distance in Awake Patients and Anesthetized Patients with Patella Alta and Trochlear Dysplasia

Objectives: The quadriceps angle (Q-angle) measures the force vector of pull extensor mechanism knee. A larger Q-angle is thought to be a predisposing factor for patellar dislocation, but previous literature has reported poor reliability and validity clinically measured Q-Angle. In response reliability, new “Standard Q-Angle” (SQA) was developed by Merchant et al. (Merchant 2020) in an attempt create standardized repeatable method measuring SQA may practical, inexpensive, valuable part physical examinations help clinicians decide if concomitant medializing osteotomy indicated stabilization procedures. However, not yet been validated patients with anatomic risk factors recurrent instability such as patella alta trochlear dysplasia. Furthermore, while previously demonstrated have strong interrater it never shown correlate measurements lateralized tibial tuberosity, Tibial Tuberosity – Trochlear Grove (TT-TG) distance. Therefore, purpose our study determine correlation between TT-TG distance instability. We hypothesized that there would positive 1. AC, Fraiser R, Dragoo J, Fredericson M. reliable Q measurement using protocol. Knee. 2020;27(3):934-939. Methods: Patients at single institution treated surgeon who had obtained dynamic 4D CT scan were included this study. procedures excluded. Standard described 2020). patient placed supine position knee extended. long-arm goniometer centered over distal arm tuberosity proximal extended up anterior superior iliac spine (ASIS). examiner then within groove measured. second stood foot patient’s bed confirm positioning. Measurements taken office, well operating room after induction general anesthesia. All performed senior author (***). Utilizing scans, TT-TG, Caton-Deschamps index (CDI), lateral inclination (LTI) described. whose CDIs 0.8 1.2 considered normal height. LTIs >11° LTI, which sensitivity 93% specificity 87% detecting Mean standard deviation values calculated demographic information, coefficients compare both awake anesthetized patients. statistical software Stata utilized all analyses (StataCorp. 2021. Statistical Software: Release 17. College Station, TX). Results: Fifty-seven knees mean age 22 years-old (±6 years). For patients, coefficient (R 2 ) -0.006 (Figure 1), R = 0.093 2). “normal height” group, value higher group 0.334) than 0.239). also greater 0.403) =0.093). strongest CDI < LTI 0.635). Conclusions: There association height inclination. only weak TT-TG. able provide useful selected cases. remains important objective radiographic characterize when planning surgery.