The anatomic variation of the superior peroneal retinaculum and inferior peroneal retinaculum and its association to peroneal tendon disorders

Abstract

The precise information for SPR and IPR reattachment is essential for the prevention of recurrent symptom of peroneal tendon dislocation/subluxation. Therefore, this study was conducted to investigate the characteristics, the attachments and morphometric parameters of the SPR, IPR and the prevalence, origin and insertion of the accessory peroneal muscles, peroneal tendon tear, and related structures. The association between the peroneal tendon tear and those structures were evaluated. One hundred and nine embalmed cadaveric legs were dissected in prone position. The SPR was variable in its length, width, angle, thickness, and insertion patterns. Based on the characteristics and insertion pattern, it could be divided into 3 types: type I (double band with subtype Ia and Ib), type II (single band) and type III (single band) with the prevalence of 57.80% (12.84%, 44.04%), 1.83%, and 41.28%, respectively. The average coordinate (X and Y-axis) of the midpoint origin measured from the tip of fibular in all types was 7.26±3.15 and 10.45±4.52 mm. The mean of length, width at the origin, width at the middle part, width at the insertion, and thickness of the IPR were 23.42 ± 3.54 (17.05-33.68), 13.29 ± 2.56 (5.83-20.92), 14.50 ± 2.37 (6.68-21.34), 10.10 ± 2.63 (4.59-19.17) and 0.48 ± 0.16 (0.20-0.87) mm, respectively. The angle of the IPR to the horizontal axis was 38.51 ± 7.07 (11.67-54.00) degrees. The low level-lying of peroneus brevis muscle in the superior peroneal tunnel was found in 78.89% cases. The inferior peroneal tunnel was divided into the upper and lower tunnels. The normal contents were the tendons of peroneus brevis (PB) and peroneus longus (PL) in the upper and lower tunnels, respectively. The accessory peroneal muscles were found in 48 cases with the prevalence of peroneus quatus (PQ), peroneus digiti quinti (PDQ) and unusual accessory peroneal muscles as 11.9%, 30.3%, and 1.83%, respectively. The prevalence of (PB) tendon tear was found in 12.84% (14 cases) and was associated with SPR type Ib with statistically significance. Precise information of the characteristic, morphometric data and coordinate of the attachment sites were essential for surgical procedure and reconstruction of SPR and IPR.