Ultrasound Characterization of Patellar Tendon in Non-Elite Sport Players with Painful Patellar Tendinopathy: Absolute Values or Relative Ratios? A Pilot Study

Abstract

Imaging findings in patellar tendinopathy are questioned. The aim of this pilot study was to characterize ultrasound measures, by calculating ultrasound ratio and neovascularization of the patellar tendon in non-elite sport players with unilateral painful patellar tendinopathy. Cross-sectional area (CSA), width, and thickness of the patellar tendon were assessed bilaterally in 20 non-elite sport-players with unilateral painful patellar tendinopathy and 20 asymptomatic controls by a blinded assessor. Ultrasound ratios were calculated to discriminate between symptomatic and asymptomatic knees. The Ohberg score was used for characterizing neovascularization. We found that non-elite sport players with patellar tendinopathy exhibited bilateral increases in CSA, width, and thickness of the patellar tendon compared to asymptomatic controls (Cohen d > 2). The ability of ultrasound ratios to discriminate between painful and non-painful patellar tendons was excellent (receiver operating characteristic, ROC > 0.9). The best diagnostic value (sensitivity: 100% and specificity: 95%) was observed when a width ratio ≥ 1.29 between the symptomatic and asymptomatic patellar tendon was used as a cut-off. Further, neovascularization was also observed in 70% of non-elite sport players with unilateral patellar tendinopathy. A greater CSA ratio was associated with more related-disability and higher tendon neovascularization. This study reported that non-elite sport players with painful unilateral patellar tendinopathy showed structural ultrasound changes in the patellar tendon when compared with asymptomatic controls. Ultrasound ratios were able to discriminate between symptomatic and asymptomatic knees. Current results suggest that ultrasound ratios could be a useful imaging outcome for identifying changes in the patellar tendon in sport players with unilateral patellar tendinopathy.

Determination of differences in ultrasound parameters for patellar tendons in males with unilateral patellar tendinopathy—An ancillary analysis of data from two randomized controlled trials

“…Since PD activity is a common feature in PT and due to our inclusion criteria, we expected to find a greater area of neovascularization in the symptomatic tendon compared to the asymptomatic tendon. We used an in‐house, custom‐made macro to objectively quantify the total area (mm 2 ) affected by neovascularization, which is in contrast to most studies that have reported neovascularization by percentage or using the ordinal Öhberg score 17,27,33,34 . One study quantified neovascularization area (mm 2 ) in a comparable fashion to our study, and found considerably less PD (mean of ~2.0 mm 2 ) compared to our median of 25.6 mm 2 35 .…”

“…PD is a common feature of PT, 17,31,32 although studies have also reported a lack of PD activity in symptomatic PT. 17,27,32 Since PD activity is a common feature in PT and due to our inclusion criteria, we expected to find a greater area of neovascularization in the symptomatic tendon compared to the asymptomatic tendon. We used an inhouse, custom-made macro to objectively quantify the total area (mm 2 ) affected by neovascularization, which is in contrast to most studies that have reported neovascularization by percentage or using the ordinal Öhberg score.…”

“…16,52 However, this limited correlation is to be expected due to the inherent variation in symptom manifestation between individuals. 53 In addition, asymptomatic tendons have been shown to demonstrate US verified structural changes, 17,27,32 and studies have demonstrated that US seem to have prognostic capabilities in asymptomatic tendons besides its overall good diagnostic capabilities in symptomatic tendons. 17,[54][55][56][57][58][59] The thickness ratios between the symptomatic and asymptomatic tendon were 1.50, 1.18, and 1.06 for the proximal, mid, and distal part, respectively.…”

“…Likewise, thickness ratio together with width ratio between symptomatic and asymptomatic tendons have been reported to demonstrate excellent discriminative validity. 17 In addition, the clinicians can use the ratios to tailor their rehabilitation program to minimize asymmetries.…”

“…10,15 These structural and physiological changes likely contribute to the increase in tendon thickness that is frequently seen with PT. 16,17 PT is characterized by localized pain during palpation of the apex patella, pain during mechanical loading of the patellar tendon and impaired physical performance. 18 The diagnosis is usually determined based on patient history and clinical examination.…”