Stenosing Tenosynovitis - A Comparative View

Stenosing tenosynovitis occurs at sites where tendon sheaths are reinforced by fibrous bands or covered by a retinaculum producing a fibro-osseus tunnel through which the tendon passes. Stenosis is either the result of narrowing of the tendon sheath or of thickening of the tendon (Palmborg, 1952). In man, stenosing tenosynovitis is typically an idiopathic condition that is primarily a degenerative or reactive process related to abnormal mechanical stress on the tendon sheath or tendon itself (Clarke et al 1998, McAuliffe 2010). Histopathology of affected tissues typically shows accumulation of mucopolysaccharide within the tendon sheath, indicating myxoid degeneration (Meachim & Roberts 1969, Clarke et al 1998, Grundman & Montavon 2001) rather than inflammatory disease. Factors that contribute to stenosing tenosynovitis include local anatomy and mechanics, and hormonal fractures. Recognition of stenosing tenosynovitis in veterinary species is relatively limited with reports of abductor pollicis longus tenosynovitis and bicipital tenosynovitis in dogs and stenosis affecting the digital flexor tendons in horses (Wilderjans et al., 2003, Owen et al 2008, Cauvin 2011, Schramme & Smith 2011). In man, the distal extremities are most commonly involved and conditions include de Quervain’s disease, trigger digits, and stenosing tenosynovitis of the flexor hallucis longus tendon.

Ultrasound is widely used in the diagnosis and assessment of stenosing tenosynovitis in man and the presence of a thickened retinaculum that constricts the osseofibrous tunnel through which the tendon runs is a key finding (Vuillemin et al 2012). Ultrasonographic changes in stenosing tenosynovitis of the abductor pollicis longus and biceps brachii have been described in dogs and palmar annular ligament syndrome and tarsal sheath lesions in horses. MRI has been used to identify tendon and tendon sheath lesions in all three species although resolution and signal intensity of normal tendons limits the assessment of small tendon structures in companion animals. However, exploitation of the magic angle effect in MRI (whereby the structure of interest is oriented at about 55 degrees to the magnetic field) can greatly enhance the visualization of tendon and ligament structures of the hand and foot (Lambe et al. 2006, Tafur et al. 2015) and may have potential in the imaging of the extremities in dogs.  [...]