Can Ultrasonography Contribute to the Diagnosis of Patellofemoral Pain Syndrome?

Patellofemoral pain syndrome (PFPS) is a common cause of knee pain in adults younger than 60 years. The prevalence of PFPS was found to be 7-28.2% and the incidence was 9.2%. In this study, we aimed to evaluate the medial and lateral cartilage thickness due to the possible relationship of PFPS with osteoarthritis, the medial and lateral retinaculum thickness as it is one of the static stabilizers of the patellofemoral joint, and the medial and lateral patellofemoral distance as it indicates patellar malposition, using ultrasonography and to compare with healthy controls. We also aimed to investigate the relationship between the measurements obtained in the PFPS group and pain intensity, functional scoring, and quality of life.This study is a non-randomized and non-blinded, cross-sectional clinical study with a control group. 54 eligible volunteers who applied to the physical medicine and rehabilitation outpatient clinic of Hitit University Faculty of Medicine.27 of the participants were patients diagnosed with unilateral PFPS, and 27 were healthy individuals without knee pain. Local ethics committee approved the study (2024/36) and informed consent was obtained from all participants.Participants were between the ages of 18-45. A positive result in at least one of the following four tests was considered diagnostic for PFPS, with pain occurring around or behind the patella and aggravated by at least one activity that placed load on the patellofemoral joint during weight bearing on the flexed knee. These tests 1) Medial or lateral patellar facet tenderness 2) Clark's test 3) Patellar apprehension test 4) Patellar tilt test. The inclusion criteria for the PFPS group were that the patients had knee pain for at least 3 month, unilateral pain, no history of knee surgery, no systemic disease, and no clinical symptoms of other knee pathologies other than PFPS. In order to exclude other pathologies that cause knee pain; patellar plica tests, Apley compression and distraction tests, McMurray tests, varus-valgus stress tests, anterior and posterior drawer tests, pivot shift and Lachman tests were performed. Those with positive results in these tests were excluded from the study.

The inclusion criteria for the control group were absence of anterior knee pain, no history of knee surgery, and no systemic disease.

Individuals with clinical symptoms related to other knee pathologies, history of trauma, history of patellar dislocation or subluxation, passive motion restriction in the knee joint, hip-spine related pain, the presence of any neurological disease affecting the extremities, inflammatory disease were excluded.

Detailed history and physical examination findings were recorded. The age, education level, marital status, height, weight, body mass index (kg/m2), duration of pain, dominant and affected extremity of all patients were recorded.

Pain levels at rest and during activity were measured using the Visual Analogue Scale (VAS).Kujala patellofemoral score was used to assess functional status of patients.Quality of life was evaluated with Short form-36 (SF-36). A B-mode ultrasound examination was performed by a radiologist with more than 5 years of experience using a Samsung RS85 Prestige (Medical Systems Corporation, Seoul, South Korea) with a high frequency (4-15 MHz) linear probe.The painful knee of the PFAS group and the non-dominant knee of the control group were evaluated by ultrasonography. The medial and lateral retinaculum thickness, medial femoro-patellar distance from the medial patellar edge to the medial femoral condyle, lateral patellofemoral distance from the lateral patellar edge to the lateral femoral condyle were measured in the axial plane with the patients in the supine position with the knee flexed 30°. The medial and lateral sides of the trochlear cartilage were measured in the axial plane with the knee in 140° flexion.