Magnetic Resonance Imaging of Patellar Tendonitis

Abstract

The radiological and MRI appearances of 24 knees with patellar tendonitis resistant to conservative therapy were analysed to identify the characteristic MRI appearance and to determine if the patellar morphology was abnormal. A significant thickening of the tendon was found in all cases; this was a more reliable diagnostic feature than a high signal within the superior posterior and central aspect of the tendon at its proximal attachment The site of the lesion shown by MRI is more compatible with impingement of the inferior pole of the patella against the patellar tendon than a stress overload of the tendon. There were no significant differences in the length of the patella, inferior pole or length of the articular surface when the patellar morphology was compared with that of a matched control group.

Patellar Tendon Strain is Increased at the Site of the Jumper's Knee Lesion during Knee Flexion and Tendon Loading

“…17 Likewise, both maximum point strain and mean localized strain significantly increased with increasing applied patellar tendon strain.…”

“…17 While the excessive tensile loading is thought to induce microscopic tears within the tendon, ultimately leading to degeneration, 19,34,38,39 the suggested pathogenesis of stress overload and tensile failure has, to date, not been able to explain why the lesion of patellar tendinopathy is localized to the proximal portion of the patellar tendon at its insertion to the inferior pole of the patella. 17 Cadaveric studies examining the surface strains of the patellar tendon through the range of motion have produced conflicting results. 1,5 One group found that on flexion, the tensile strain on the patellar tendon increased on the anterior aspect of the tendon and decreased on the posterior aspect.…”

“…12,17 In this theoretical scenario, the inferior pole of the patella is thought to impinge against the proximal portion of the patellar tendon during knee flexion. 12,17 It is theorized that an alteration in the type of load (compression vs tension) experienced by the tendon will result in an adaptational change in the extracellular matrix of the tendon, making it more susceptible to injury. 12 However, this theory has never been rigorously examined.…”

Tendinopatia patelar

“…A hipótese de que o pólo inferior da patela pode influenciar o aparecimento da tendinopatia patelar foi reforçada com a existência de um pólo inferior longo da patela em pacientes com tendinopatia patelar (18)(19)(20) . Porém, o pólo inferior da patela longo pode, em verdade, representar um osteófito de tração, causado por determinada força de alta tensão repetitiva e pode não ser uma anormalidade preexistente que contribuiu para a tendinopatia patelar (19) .…”

Etiology of Patellar Tendinopathy in Athletes

“…Laduron et al 33 suggested that there might be an impingement between the deep fi bers of the proximal patellar tendon and the lateral part of the femoral trochlea during full extension. Johnson et al, 34 however, found confl icting results in a magnetic-resonance-imaging study. They found suggestion of this impingement during knee extension in only 2 of the 24 knees they studied and therefore discounted Laduron's theory.…”