Reliability testing of sonographic techniques in detecting lateral displacement of patellar tendon

Objectives

Patellofemoral pain syndrome (PFPS), a common knee condition, is characterized as presence of peripatellar pain during activities especially during loading of the lower extremity. Gonzalez-Suarez et al. (2021) developed a sonographic technique that assessed patellar tendon displacement within the trochlear groove. This study aims to determine the reliability of this sonographic technique.

Methods

Intra-rater and inter-rater reliability study of three sonologist on the lateral displacement of the patellar tendon using ultrasound. Patellar tendon displacement was assessed using the three novel sonographic measurement techniques: 1) region of trochlear groove where the patellar tendon midpoint is located, 2) distance between deepest portion of the trochlear groove and patellar tendon midpoint and 3) percentage of lateral displacement of the patellar tendon. The measurements were done with the patients in supine and standing.

Results

Ten participants with a mean age of 27.6 ± 1.56 years were included in the study. Pilot studies were done to improve the sonographic technique. Intraclass correlation coefficients yielded good to excellent inter-rater and excellent intra-rater reliability (>0.75) in the supine and standing positions except the inter-rater reliability of the region of the trochlear groove where patellar tendon midpoint is in supine position.

Conclusion

The sonographic techniques for measurement of lateral patellar tendon displacement showed good to excellent intra-rater and inter-rater reliability between sonologists of different levels of expertise using a well-defined scanning protocol.