[Sonographic standard values for the patellar tendon in competitive athletes]

The sonographic validity of a thickened tendon as a morphological correlate of patellar tendinopathy is beyond dispute, regarding the proximal insertion at the very least. There is, however, a lack of mandatory standard values for competitive athletes and normal individuals. In addition, research findings concerning the clinical relevance of qualitative changes such as hypoechogenic regions are still inconclusive.

202 national squad athletes from the German track and field federation and 199 age-matched normal individuals were examined sonographically.

404 patellar tendons of athletes were compared as to tendon diameter at the (i) proximal insertion, (ii) waist, and (iii) distal insertion with 398 patellar tendons of normal individuals using the portable ultrasound scanner "Just Vision". Furthermore, qualitative pathologies and clinical symptoms were assessed.

Athletes reported more clinical symptoms and their tendons were thicker than normal tendons at all three positions (all p's < 0.01). In athletes, proximal diameters above 6.0 mm were very likely to go along with clinical symptoms. There was an association between tendon diameter and symptoms at all three positions among the athletes, whereas in controls, this was only true for the proximal insertion. Only few consistent qualitative differences were found between athletes and normal individuals.

The pattern of results confirms the clinical relevance of the proximal tendon diameter for patellar tendinopathy and provides standard values which should be evaluated in future research with regard to their prognostic utility in competitive sports. The importance of qualitative pathologies such as hypoechogenic regions could not be firmly asserted.