Ultrasound and Power Doppler findings in jumper's knee — preliminary observations

Abstract

Objective: to examine a group of high risk athletes, for signs of inflammation in jumper's knee (JK) by gray-scale ultrasonography (US) and color/Power Doppler findings in JK. Subjects and methods: eighteen high-elite basketball players participated in the investigation after a match. Seven players were examined by ultrasound before the match as well. The players were clinically examined for signs of JK and filled in a questionnaire concerning previous and present knee symptoms. Results: clinical signs of JK were found in 13 knees. Of these knees, ten had hypoechoic areas and six had Power Doppler flow. Four players reported symptoms of JK and clinical examination suspected the same. Three of them had both hypoechoic areas and Power Doppler flow. Fourteen players were asymptomatic at the time of examination but both hypoechoic areas and Power Doppler flow was found in the patellar tendons of four players. No correlation was found between clinical findings, symptoms of JK and US findings — including Power Doppler. The risk of type II error in this material is considerable. Conclusion: an association between gray-scale US and color/Power Doppler was found in JK which may suggest an inflammatory component to be a part of the pathogenesis of JK.

Introduction

A disagreement in the literature exists on whether or not jumper's knee (JK) is an inflammatory rather than a degenerative condition and most authors believe in the degenerative theory due to the lack of histological evidence of inflammation (Almekinders and Temple, 1998, Davies et al., 1991, Cook et al., 1997, Kälebo et al., 1991, Kahn et al., 1996, Nichols, 1992). However, in treatment of JK, NSAID's and steroid injections are often used with marked clinical effect pointing towards an inflammatory component in this condition (Almekinders and Temple, 1998, Nichols, 1992). Ultrasonography is a valuable tool in the diagnosis of JK (Davies et al., 1991, Nichols, 1992, Laine et al., 1987, Weinberg et al., 1998). JK is a painful condition in the patellar tendon and is seen among athletes who submit their knee extensor mechanism to intense and repeated stress and especially basketball players are at high risk (Cook et al., 1997).

The gray-scale ultrasonographic changes consisting of hypoechoic areas in the patellar tendon in both longitudinal and transverse scans (Fig. 1, Fig. 2) are a constant observation at all the stages of the disease (Davies et al., 1991, Nichols, 1992, Laine et al., 1987, Weinberg et al., 1998, Cook et al., 1997). In some selected materials of late stage disease a very close relationship has been described between clinical symptoms and signs and ultrasonographic changes (Davies et al., 1991, Cook et al., 1997, Kälebo et al., 1991). These findings have been in accordance with subsequent histological examination after operation. In contrast, in earlier stages of the disease, the results may be more dissociated (Lian et al., 1996), and no histological evidence has so far been obtained from these cases as they are not operated and no biopsies are taken from these tendons.

Recently, it has been possible to apply Power Doppler in the examination of musculoskeletal tissues and by this method depict hyperaemia in musculoskeletal inflammatory disease (Newman et al., 1996, Breidahl et al., 1996).

We had the opportunity to test top-players from the Danish basketball elite before and after a match. The aim of the present study was to examine, by ultrasonography, a group of high risk athletes, high-elite basketball players, for signs of inflammation in JK using Power Doppler. We examined the athletes before and after a clinical situation characterized by high intensity stress to evaluate a possible effect on tendon changes. We also compared gray-scale US and color/Power Doppler findings in JK.

The examination was carried out by both gray scale sonography and by Power Doppler.

The correlations between symptoms, clinical findings and ultrasonographic findings were also investigated in this non-selected, prospective material.