Fig. 5. Displacement of the deep digital flexor tendon from its normal position. Note widening of the bursa space (solid arrows) and the mismatch of the deep digital flexor tendon on the sagittal ridge (open arrow).
Fig. 4. Leakage of dye from the bursa. Leak is most easily seen on the lateral projection (open arrow). PP-PD projection shows leakage from the lateral aspect of the bursa (arrow).
deep flexor to the navicular bone were seen as gaps in the dye column. A previous study proved these to be adhesions on necropsy.5 MRI has detected fibrous scar tissue between the proximal suspensory ligament of the navicular bone and the deep digital flexor tendon.3 Contrast stud- ies show this finding as a shortening of the length of the bursa. The bursa loses its apostrophe shape and is seen as a small fluid sac only as long as the navicular bone. This illustrates some of the restric- tion that is thought to occur as a result of this
common pathology seen in navicular disease.6 It follows that the flexor fibrocartilage is the most frag- ile structure in this area and therefore the most readily damaged. Although this is the most com- mon change seen, it is not more important than any other change. The third most common finding is splits or filling defects along the bursal surface of the deep digital flexor tendon. This is a common MRI finding as well.3 In these cases, these splits were invariably associated with thinning and erosions of the flexor surface of the navicular bone. Communication between the bursa and the distal interphalangeal joint is a sign of coffin joint capsule injury and is often associated with collateral liga- ment desmitis.7 The bursa and joint are in close proximity, and injury to the palmar capsule could result in this communication. Adhesions of the
200 2013 Vol. 59 AAEP PROCEEDINGS
Fig. 6. Damage to the impar ligament seen as dye within the impar ligament (arrow).
