Location of the motor entry point and intramuscular motor point of the tibialis posterior muscle: for effective motor point block.

The aim of this study was to elucidate the anatomical location of the motor entry point (MEP) and intramuscular motor point (IMP) of the tibialis posterior muscle for effective motor point block. Thirty-six fresh specimens from 20 adult Korean cadavers (11 males and 9 females) were investigated. The reference line between the most proximal-medial articular margin of the tibia (MPM) at the level of the knee joint and the most distal point of the malleolus of the tibia (MDM) on the surface were identified. The mean length of the reference line was 326.5 ± 27.1 mm. There were 82.5% of the total number of MEPs located at 10-30% and 67.9% of the total IMPs were 10-40% from the MPM. The safety zone for botulinum toxin (BTX) injections on the medial approach was 10-40% from the MPM. In addition, insertion of the needle to a depth of 3.5 cm from the surface of the skin was effective. These results may assist in determining more accurate localization of injection sites.