Heel spur is an osteophytic outgrowth just anterior to the tuberosity of the calcaneus, extending along its entire width or about 2 to 2.5 cm. The apex of the spur is embedded in the plantar fascia directly anterior to its origin. The condition may exist without producing symptoms, or it may become very painful, even disabling.
Calcaneal spurs are of three types:
1. Those which are large in size but symptomless, because the angle of growth is such that the spur does not become a weight-bearing point and/or the inflammatory changes have been arrested. This type is usually found incidentally when the foot is x-rayed for some other purpose.
2. Those which are of large size and painful upon weight-bearing, because the pitch of the calcaneus has been altered by a depression of the longitudinal arch and, as a result, the spur may become a weight-bearing point, sometimes causing intractable
DuVRIES HL. Heel Spur (Calcaneal Spur). AMA Arch Surg. 1957;74(4):536-542. doi:10.1001/archsurg.1957.01280100054008