THE LOCATION OF PATHOLOGY IN PATELLAR TENDINOPATHY
Authors: J D Rees, J Houghton, A Srikanthan, A West
Journal: British Journal of Sports Medicine (2013)

Introduction There is a general belief that the pathology of the patellar tendon is limited to the proximal pole, however this has not been studied in detail. This is unfortunate since the location of pathology within a tendon, or supporting structure(s), should be considered when designing a treatment programme. This lack of clarity has led to different definitions of patellar tendinopathy being used in different studies of physical rehabilitation. The Defence Medical Rehabilitation Centre at Headley Court provides diagnosis and musculoskeletal rehabilitation for the British Armed forces and patellar tendinopathy is a common presentation. The purpose of this study was to retrospectively assess the location and severity of pathology of the patellar tendon. Methods A retrospective analysis of all ultrasound scans of patellar tendons performed at Headley Court between 2008 and 2011 was performed. The scans were then graded by the lead author (JR) in conjunction with a consultant musculoskeletal radiologist (AW). For all abnormal tendons the following information was recorded; location, maximum tendon thickness, fibres involved, grey scale tendinopathy grade (0–3) after Archambault et al ,1 neovascularity grade (modified Ohberg after Hoksrud et al 2), presence of tendon calcification and bony irregularity. Results One hundred and forty-three scans were identified. Of these 72 abnormal scans were suitable for the study. The age range was between 22 and 47 years with a mean average age of 30. There were 70 scans from male patients and 2 from female patients. The results are displayed in table 1 above. Table 1 Patellar tendinopathy; distribution of site and severity of pathology Tendon area No of tendons Mean average max Fibres involved Grade grey scale Neovascularity score Tendon Bony involved Total 72 thickness (mm) Superficial Deep G1 G2 G3 NO N1 N2 N3 Calcification Irregularity prox only 40 7.8 23 39 0 2 38 4 11 13 12 8 14 distal only 12 8.0 8 12 1 2 9 0 1 2 9 1 9 prox + distal 7 7.7 6 7 0 1 6 1 0 2 4 3 4 pan tendon 6 9.2 4 6 0 2 4 0 0 2 4 4 5 prox + mid 4 10.0 4 4 0 0 4 0 2 1 1 1 2 mid +distal 2 10.0 2 2 0 0 2 0 0 0 2 1 1 mid only 1 7.0 1 1 0 1 0 1 0 0 0 0 0 Discussion This study confirms that patellar tendinopathy is not restricted to the proximal pole. Although the proximal pole was the most commonly involved location, distal pole involvement was common occurring in 38% of scans. The vast majority of previous studies have concentrated on proximal disease to the neglect of distal disease. Involvement of the mid patellar tendon was less common and when it did occur it almost always occurred in conjunction with pathology of either the proximal and/or distal poles. Isolated involvement of the middle portion of the patellar tendon was very rare (occurring in only one scan). As a result of this study the following recommendations are made: 1. When scanning the patellar tendon all the anatomical areas are scanned carefully, including the distal pole. 2. The term ‘patellar tendinopathy’ is imprecise and insufficient. Abnormalities should be referred to as occurring at the specific site (ie, proximal and/or distal and/or mid tendon). The term ‘jumper's knee’ is equally imprecise and should be abandoned. 3. Future studies should stratify for the location of pathology in the patellar tendon as different treatments may have different results depending on the location of the pathology.