The Tibial Tuberosity-Rotational Angle as a Novel Predisposing Parameter for Patellar Dislocation.

Area of Science:

• Orthopedic surgery
• Radiology
• Biomechanics

Background:

• The tibial tuberosity's (TT) curved anterior tibial cortex complicates accurate linear malposition measurements.
• Traditional linear measurements may not fully capture tibial tuberosity malposition.

Purpose of the Study:

• Introduce the tibial tuberosity-rotational angle (TT-RA) as a novel anatomical parameter.
• Validate TT-RA's predictive capability for patellar dislocation.

Main Methods:

• Compared seven radiological parameters in 46 patellar dislocation patients and 46 controls using MRI.
• Key parameters included TT-rotational angle (TT-RA) and TT-trochlear groove (TT-TG) distance.
• Assessed predictive values using multivariable logistic regression analysis.

Main Results:

• TT-RA, TT-TG distance, and knee rotation were significantly different between groups.
• TT-RA (OR, 1.57), TT-TG distance (OR, 1.52), and knee rotation (OR, 0.75) were significantly associated with patellar dislocation.
• High intra- and interobserver reliability was observed for parameter measurements.

Conclusions:

• The TT-RA is a reliable indicator of patellar instability.
• TT-RA provides a valuable alternative measurement when TT-TG distance is indeterminate.