A New Anatomical Classification for Tibialis Posterior Tendon Insertion and Its Clinical Implications: A Cadaveric Study

Abstract

The variations in the tibialis posterior tendon (TPT) could not be defined by previous classification; thus, this study used a larger-scale cadaver with the aim to classify the types of TPT insertion based on the combination of the number and location of TPT insertions. A total of 118 feet from adult formalin-fixed cadavers were dissected (68 males, 50 females). The morphological characteristics and measurements of TPT insertion were evaluated. Four types of TPT insertions were classified, wherein the most common type was type 4 (quadruple insertions, 78 feet, 66.1%), which was divided into four new subtypes that were not defined in the previous classification. The second most common type was type 3 (triple insertions, 25 feet, 21.2%) with three subtypes, including the new subtype. Type 2 was found in 13 feet (11%), and the rarest type was type 1 (2 feet, 1.7%), wherein the main tendon was only attached to the navicular bone and the medial cuneiform bone. We suggest high morphological variability of the TPT in relation to the insertion location, along with the possibility of significant differences according to race and gender. Moreover, this classification will help clinicians understand adult flatfoot deformity-related posterior tibial tendon dysfunction (PTTD).

Anatomical Study of Sites and Surface Area of the Attachment Region of Tibial Posterior Tendon Attachment

“…In addition, no significant difference by sex or laterality was seen between types. Previous studies have reported different results from this study [ 4 , 5 , 6 , 7 , 8 ]. In particular, previous studies using a similar classification method were 80 feet (European populations) [ 7 ] and 118 feet (Korean populations) [ 8 ], but the results were also different from this study.…”

“…Previous studies have reported different results from this study [ 4 , 5 , 6 , 7 , 8 ]. In particular, previous studies using a similar classification method were 80 feet (European populations) [ 7 ] and 118 feet (Korean populations) [ 8 ], but the results were also different from this study. Therefore, it was suggested that there is high morphological variability of the TPT in relation to the insertion location, along with the possibility of significant differences according to race and gender.…”

“…Branching and attachment to up to eight bones was reported among any of the MCB, ICB, LCB, CB, calcaneus, and 1st–5th metatarsal bones. In addition, Park et al [ 8 ] reported four types of TPT insertions classified using 118 feet, wherein the most common type was type 4 (quadruple insertions, 78 feet, 66.1%), which was divided into four new subtypes that were not defined in the previous classification. The second most common type was type 3 (triple insertions, 25 feet, 21.2%) with three subtypes, including the new subtype.…”

“…As these previous studies show, no consensus has been reached regarding sites of TPT attachment [ 4 , 5 , 6 , 7 , 8 ]. Possible obstacles to the development of such a consensus include ethnic differences, differences in laterality, and differences in numbers of samples [ 4 ].…”

“…Possible obstacles to the development of such a consensus include ethnic differences, differences in laterality, and differences in numbers of samples [ 4 ]. In addition, while previous studies [ 4 , 5 , 6 , 7 , 8 ] have considered that the NB, MCB, and LCB are the main sites of TPT attachment, the degree of contribution of these attachment sites has not been quantified, and whether they contribute significantly to the actions of the TPT remains unknown. Main attachment sites thus need to be clarified by calculating and comparing the surface area ratio of individual attachment sites.…”