The value of the peroneus brevis tendon cross-sectional area in early diagnosing of peroneus brevis tendinitis: The peroneus brevis tendon cross-sectional area

Abstract

A thickened peroneus brevis tendon has been considered to be an important morphologic parameter of peroneus brevis tendinitis (PBT). Previous researchers have found that the peroneus brevis tendon thickness (PBTT) is correlated with inflammation of the peroneus brevis tendon. However, inflammatory hypertrophic change is different from simple thickness. Thus, we devised the peroneus brevis tendon cross-sectional area (PBTCSA) as a new diagnostic parameter to analyze the hypertrophy of the whole PBT. We assumed that the PBTCSA is a major morphologic parameter useful for early PBT diagnosis. Peroneus brevis tendon images were collected from 22 patients with PBT and from 22 normal subjects who underwent ankle-magnetic resonance imaging and revealed no evidence of PBT. The T1-weighted axial ankle-magnetic resonance imaging images were evaluated at the ankle level from all participants. The PBTT was measured as the thickest point at the transverse image of the peroneus brevis tendon. The PBTCSA was measured as the cross-sectional ligament whole area of the peroneus brevis tendon that was most hypertrophied in the axial A-MR images. The average PBTT was 2.22 ± 0.29 mm in the normal group and 2.85 ± 0.36 mm in the PBT group. The average PBTCSA was 6.98 ± 1.54 mm2 in the normal group and 13.11 ± 2.45 mm2 in the PBT group. PBT patients had significantly greater PBTT (P < .001) and PBTCSA (P < .001) than the normal group did. A receiver operating characteristic curve analysis revealed that the most suitable cutoff value of the PBTT was 2.51 mm, with 81.8% sensitivity and 81.8% specificity, and an AUC for the score was 0.93. The most suitable cutoff value of the PBTCSA was 10.08 mm2, with 90.9% sensitivity and 90.9% specificity, and AUC for the score was 0.98. Even though the PBTT and PBTCSA were both significantly associated with PBT, the PBTCSA was a more sensitive diagnostic parameter.

Figure 1.

Measurement of both peroneus brevis tendon thickness (PBTT) (white arrow) (A) and peroneus brevis tendon cross-sectional area (PBTCSA) (white arrow) (B) in the peroneus brevis tendinitis carried out on A-MRI transverse T1-weighted images. A-MRI = Ankle-Magnetic resonance imaging, PBTCSA = peroneus brevis tendon cross-sectional area, PBTT = peroneus brevis tendon thickness.

Figure 2.

ROC curve of PBTT and PBTCSA for prediction of PBT. The best cutoff point of PBTT was 2.51 mm versus 10.08 mm² of PTTCSA, with sensitivity 81.8% versus 90.9%, specificity 81.8% versus 90.9% and AUC 0.93 versus 0.98, respectively. PBTT AUC (95% CI) = 0.93 (0.87–1.00). PBTCSA AUC (95% CI) = 0.98 (0.96–1.00). AUC = area under the curve, PBT = peroneus brevis tendinitis, PBTCSA = peroneus brevis tendon cross-sectional area, PBTT = peroneus brevis tendon thickness, ROC = Receiver operating characteristic.