2025 ISAKOS Biennial Congress ePoster
The Effect of Knee Rotation Angle on Patellofemoral Instability
Jeffery D St. Jeor, MD, Winston Salem UNITED STATES
Morgan E Noel, MD, Winston Salem, NC UNITED STATES
Thomas Mason, BS, Winston Salem, NC UNITED STATES
Mina Entessari, MD, Winston Salem, NC UNITED STATES
Alan W Reynolds, MD, Greensboro, NC UNITED STATES
Brian R. Waterman, MD, Winston-Salem, NC UNITED STATES
Nicholas A. Trasolini, MD, Winston Salem, NC UNITED STATES
Atrium Health Wake Forest Baptist, Winston Salem, NC, UNITED STATES
FDA Status Not Applicable
Summary
The study demonstrated that KRA is associated with PI even when controlling for TT-TG; additionally, KRA>8.07 may be an independent risk factor for the development of patellofemoral instability.
ePosters will be available shortly before Congress
Abstract
Introduction
Tibial tubercle–trochlear groove (TT-TG) distance is a risk factor for patellofemoral instability and is part of determining the management of instability. However, the role of knee rotation angle (KRA) on instability and TT-TG remains a topic of investigation.
Methods
A retrospective review was conducted of patients with patellofemoral instability who underwent medial patellofemoral ligament reconstruction (MPFLr) at a single institution between 2018 and 2023. The baseline group was patients who underwent isolated partial meniscectomy (IPM) during that same period. Parameters of interest were TT-TG and KRA measured on MRI. Data analysis was completed with SAS Viya (Cary, NC); significance was alpha <0.05.
Results
122 patients who underwent MPFLr (73 female, 49 male; mean age 21.1 [±9.8] years) and 96 patients who underwent IPM (47 female, 49 male; mean age 38 [±17.6] years) were identified. The average TT-TG for MPFLr and IPM was found to be significantly different at 15.3mm (±5.4) and 11.4mm (±3.5) respectively (p<0.001). The average KRA for MPFLr and IPM was also found to be significantly different at 5.9° (±4.1) and 4.7° (±2.8) respectively (p=0.018). Examining the relationship of TT-TG and KRA, via linear regression, revealed a positive correlation. For every 1mm increase in TT-TG, KRA increased by 0.20° (p=0.034). When examining MPFLr vs IPM via logistic regression, both KRA and TT-TG were significantly associated with MPFLr (p=0.034 and p<0.001 respectively). Further analysis, via decision tree, demonstrated that a KRA>8.07° and TT-TG>15mm had a specificity of 76% and 85% respectively. Additionally, a binary analysis at these values was significantly correlated with MPFLr (p=0.001 KRA and p<0.001 TT-TG).
Conclusion
The results of the study demonstrated that KRA is associated with PI even when controlling for TT-TG. Additionally, KRA>8.07 may be an independent risk factor for the development of patellofemoral instability.