Jennifer L. Haupt DVM, John P. Caron DVM, MVSc, Diplomate ACVS Veterinary Surgery August 2010 39 6 742-47 Objectives: To compare the proportion of the proximal recess of the navicular bursa that could be examined through a single endoscopic portal and the severity of iatrogenic lesions between conventional and modified approaches. Design: Descriptive study. Sample Population: Equine cadaver forelimbs (n=16). Methods: Arthroscopic access to the navicular bursa in 1 limb of each pair was by a conventional approach and in the other limb, by a modified approach using sharp dissection through the distal digital flexor sheath, immediately palmar to the T ligament. The time required to access the bursa and the estimated proportion of the navicular bone that could be seen with each approach were recorded. Iatrogenic damage to the navicular bone and the deep digital flexor tendon (DDFT) were quantified. Results: The mean access time to the navicular bursa using the conventional approach was 1.21±0.41 minutes compared with 2.09±0.86 minutes using the modified technique. The estimated proportions of the bursa visible through a single endoscopic portal using the conventional and modified approaches were 60% and 80%, respectively. Scores for navicular bone (P=.003) and DDFT (P=.012) damage using the conventional approach were significantly higher than those using the modified approach. Conclusions: A modified, transthecal approach to the navicular bursa under direct observation resulted in significantly less iatrogenic damage than the conventional approach. Clinical Relevance: With experience, the modified approach is straightforward, reasonably rapid, and allows near-complete examination of the navicular bursa through a single portal, with minimal iatrogenic damage to the intrabursal structures.