Carpet-layer's knee. An ultrasonographic study.

In order to reveal abnormalities in the soft tissue of the anterior part of the knee, caused by protracted mechanical stress, we performed ultrasound studies of both knees of 95 male workers in the carpet-laying and parquet floor trade (group 1). Seventy-three painters (group 2) served as controls. In group 1, an anechoic fluid collection was detected in 10 knees, localized in the superficial infrapatellar bursa and in one patient in the prepatellar bursa, whereas there were no cases of fluid accumulation in the controls. A hypoechoic, oval subcutaneous thickening in the anterior wall of the superficial infrapatellar bursa was detected in 35 (18.4%) and 4 (2.7%) knees, respectively. Prepatellar subcutaneous thickening was detected in 45 knees (23.7%) in group 1, but in only 2 knees (1.4%) in group 2. Two knees in group 1 had thickened and inhomogeneous patellar tendons, while one in group 2 had a thickened and 2 both thickened and hypoechoic patellar tendons. We conclude that ultrasonography is a useful method for the detection of bursitis and soft tissue changes in carpet-layers. Detection of a fluid collection in a bursa does not necessarily denote bursitis of clinical importance, but does signify irritation due to work stress. Patellar tendon pathology is rare among carpet-layers and is probably unrelated to the occupation.