How to Perform Diagnostic Stifle Arthroscopy With the Use of a Needle Arthroscope in Standing Horses

It has been suggested that athletic injuries to the stifle may account for 40% of injuries in certain disciplines. In the authors’ experience, the prevalence of stifle injuries in most disciplines is not accurately known. Furthermore, until the past 10 to 15 years, very little attention has been given to athletic injuries in the stifle, in part because of diagnostic limitations and lack of successful treatment options. Limiting definitive diagnosis is the inability to accurately image the soft tissue and bone with high sensitivity and specificity. Although routine radiography can be helpful in certain cases, many lesions, particularly those of soft tissues, go undetected. Ultrasonographic examination of the equine stifle joint has helped broaden diagnosis of stifle lesions. This is especially true of soft-tissue structures, namely the collateral ligaments, patellar ligaments, and menisci. Ultrasound examination of the cruciate ligaments still poses a problem because of the orientation and deep anatomic location of these structures. Moderate to severe pathology appears to be readily detected with the use of ultrasonography, but detection of slight to moderate lesions is difficult. In a recent study, Cohen et al nicely defined the sensitivity (79%) and specificity (56%) of ultrasonography in the equine stifle joint, with surgery used as the gold standard. A positive predictive value (73%) and negative predictive value (62%) were also determined for equine ultrasonography on the basis of this study. These results point out the current limitation of ultrasonography of the equine stifle. Other current methods for diagnostics in the stifle currently require general anesthesia, specifically computed tomography, magnetic resonance imaging, and routine arthroscopy, which remain the gold standards. It is also worth noting that these later diagnostics are typically only available at large referral centers, limiting their availability in a more routine practice setting. Additional methods to safely and quickly assess the stifle in a typical practice setting would be advantageous to aid a more accurate diagnosis of stifle