The sustentaculum tali (ST) is located at the medial aspect of the tarsus and is considered a rare anatomic location for diseases. This retrospective case series describes the management of five horses with septic and non-septic ST injuries. All horses were treated surgically with tenovaginoscopy, ST fragment and exostosis removal. In two cases, lameness was caused by an exostosis involving the ST and the plantar aspect of the medial trochlear ridge (MTR). There are no reports of exostosis involving ST and MTR causing lameness. In four horses, the long-termoutcome was considered good and the horses were able to return to the previous level; one horse developed a recurrence of ST and MTR exostosis leading to recurrence of lameness. Curettage of the ST and MTR exostosis, removal of fragments and tarsal sheath adhesions play a pivotal role in increasing prognosis and long-termoutcome. Poor prognosis is correlated with exostosis recurrence.