Yamamoto N, et al. - From four hospitals, data of 3,585 consecutive patients undergoing primary total knee arthroplasty (TKA) between 2012 and 2017 were retrospectively reviewed in order to determine the prevalence and clinical findings of calcaneal insufficiency fracture (IF) following TKA. Following TKA, 17 (0.5%) of the 3,585 patients presented with calcaneal IF. Based on findings, researchers recommend suspecting calcaneal IF in patients presenting with ipsilateral foot pain following TKA; this should particularly be preferred for female patients with a relatively high BMI and osteoporosis. Calcaneal IF were classified into three types based on its location: type 1, fracture by traction force around the Achilles tendon insertion; type 2, compression fracture around the posterior subtalar joint; and type 3, fracture by ground reaction force at the bottom of the calcaneus. Differences in conditions and changes in mechanical loading of the lower extremity and bone quality following TKA may explain these variations in calcaneal IF.