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Radiographic analysis of patellar tilt
R P Grelsamer1, A N Bazos, C S Proctor
1Columbia-Presbyterian Center for Sports Medicine, New York.
The Journal of Bone and Joint Surgery. British Volume
|September 1, 1993
Summary
The patellar tilt angle, a new radiographic measurement, effectively detects patellofemoral malalignment. This measurement shows high sensitivity and accuracy in identifying knee extensor mechanism issues.
Area of Science:
- Orthopedics
- Radiology
- Biomechanics
Background:
- Patellofemoral malalignment is a common cause of anterior knee pain.
- Accurate radiographic assessment is crucial for diagnosing and managing this condition.
Purpose of the Study:
- To introduce and validate the radiographic measurement of the patellar tilt angle.
- To assess its efficacy in detecting patellar malalignment compared to the congruence angle.
Main Methods:
- Radiographic measurement of the patellar tilt angle was performed using Merchant-type views with the knee in 30 degrees of flexion.
- The tilt angle was defined as the angle between the patellar edges and the horizontal.
- Measurements were compared between patients with suspected patellofemoral malalignment and healthy controls.
Main Results:
- The mean patellar tilt angle was significantly higher in patients (12° ± 6°) compared to controls (2° ± 2°, p < 0.01).
- A tilt angle of 5° was established as the upper limit of normal.
- The patellar tilt angle demonstrated high sensitivity (85%) and accuracy (89%) for detecting malalignment, surpassing the congruence angle (25% sensitivity, 62% accuracy).
Conclusions:
- The patellar tilt angle is a sensitive, specific, and accurate radiographic tool for identifying patellar malalignment.
- This measurement aids in the diagnosis of extensor mechanism dysfunction and related knee conditions.