Approach towards psoas syndrome risk modeling in preoperative planning for THA

Psoas syndrome after THA has received much attention in recent years. In some cases, the cause of pain cannot be found in a critical overhang of the implant cup, but is mainly unknown. We developed an approximation of modeling the medial part of the tendon of m. iliacus in 201 THA patients. We found length changes of the tendon of 7,73 mm ± 8,55 mm (range: -26,37 mm to 30,30 mm) and angular changes at the PSIS of 2,58 ° ± 1,72 ° (range: 0 to 7,91 °) and at the lesser trochanter of 10,53 ° ± 7,70 ° (range: 0,27 ° to 41,19 °). Furthermore, we identified 19 cases in whom the tendon wrapped over different bony structures than the acetabular region. Hence, we think that the m. iliacus tendon should be considered for analysis of risk factors in the preoperative planning process for THA.