The patellar retinaculum (the tissue around ... the calf muscle to the bones in the arch of the foot. The reason most are describing the injury as "rare" is because the two are typically unrelated ...

The Celtics announced on Tuesday that Porzingis has been diagnosed with “a torn medial retinaculum ... up to the 7-foot-3 forward. Mazzulla on Kristaps: “It’s a serious injury.