A case-controlled study was conducted to assess the significance of fragmentation of the distal border of the navicular bone, the shape of the palmar cortex and proximal and distal extensions of the palmar surface.
The study included 55 sound and 377 lame horses examined during prepurchase and lameness exams, respectively. Lame horses included those that blocked sound after diagnostic palmar nerve. Radiographs were evaluated retrospectively and lesions were recorded, measured, graded and compared between sound and lame horses; including, specifically, those with a diagnosis of navicular disease.
The majority of the lame horses included in the study (56%) had a foot problem other than navicular bone pathology, 24% had navicular pathology and 20% had no definitive diagnosis. Fragmentation of the distal navicular border was found in 4% of sound horses, 9% of lame horses and 24% with a diagnosis of navicular disease.
Most fragments were seen at the junction between the distal horizontal border and the sloping lateral or medial borders of the bone. The majority (71%) were noted as an irregular contour of the distal border, while 58% had a distinct radiolucent area. About half (52%) only affected one side of one limb, most often the limb showing the most lameness. The palmar cortex was thicker in lame horses compared with controls. The authors conclude fragmentation of the distal navicular border may be part of navicular disease.
— Biggi M and Dyson S. EVJ 2012;44:325-331.
Endoscopic examination the navicular bursa was…