Diagnostic Ultrasound Of The Musculoskeletal System
Diagnostic ultrasound of the musculoskeletal system has been a significant component of sports medicine and orthopedics in both human and equine medicine for decades. With the advent of higher resolution probes, diagnostic musculoskeletal ultrasound in small animals is becoming more common and a welcomed tool in the world of sports medicine, soft tissue injury and rehabilitation.
Advantages of using ultrasound in the diagnosis and monitoring of treatment of small animal soft tissue injuries include that most exams do not require anesthesia and it is offered at a lower cost than MRI, which allows for easy and more frequent and more affordable rechecks. Ultrasound also allows certain structures to be visualized in dynamic form during movement, which may aid the practitioner in their complete evaluation. In general diagnostic ultrasound can offer a quick, non-invasive way to diagnose soft tissue injuries.
Some disadvantages are that there are few practioners/radiologists that practice enough volume to excel in the area of musculoskeletal ultrasound and the limited availability of practioners in general. This also reveals a drawback of all ultrasound which is most ultrasound imaging is operator dependent in addition to acquiring and analyzing the images correctly.
Common orthopedic applications of musculoskeletal ultrasound include scanning for tendon, ligament and muscle injuries, aid in analyzing joints and uses as guide in joint injections, identifying miscellaneous soft tissue problems, often sports related injuries (see above: left supraspinatus tendon with core lesion in green), and ultrasound guided injections, often regenerative medicine.
In many of the older initial ultrasound studies lower powered probes provided unclear hard to read images. Many of these used were 7.5 MHz linear transducer probes because of its flat application surface and its resolving power. Currently, higher resolution transducers between 10-20 Mhz linear probes are the most popular used.
Simple scanning principles include familiarity with the local anatomy, using the contra-lateral limb as comparison for any questionable tissue changes or peculiarities and whenever possible obtaining radiographs to use in addition to ultrasound to aid in a final diagnosis. In addition when scanning tendons and ligaments, they should always be viewed in the extended positioned and the probe should always be perpendicular to the tendon fibers to avoid off angle artifacts.
Ultrasound is valuable for assessing joint disease. Joint effusion, thickening of the joint capsule and cartilage defects can be identified sonographically. It is also possible in certain instances to detect bone destruction, inflammation, and periosteal inflammation. Instabilities of tendons and ligaments are, too, often recognized with the aid of a dynamic sonographic analysis. Partial or complete muscle or tendon tears can be identified and differentiated. The healing process can be monitored and rehabilitation exercises and activity can be adjusted accordingly. Instead of guessing and estimating tissue integrity, ultrasound gives a noninvasive look at the healing process and allows the therapist to adjust the patient’s rehab program more appropriately for the individual’s stage of healing.
Most of the injuries that are in the area of the shoulder, flexor carpi ulnaris, iliopsoas, stifle or the achilles tendon, such as disruption of the tendons, core lesions, older injuries with scar tissue or calcification, or tenosynovitis can often be differentiated by ultrasound.
Regenerative medicine can be introduced via ultrasound guided injection into the precise areas of need (see above images) and be followed for the appropriate healing indications such as reduction in peri-tendon edema, reduction in cross sectional area of tendons and ligaments, increased collagen deposition, injured section becomes more echogenic and fiber pattern becomes more continuous with residing tendon/ligament. In addition, prognosis and healing advancement can be reported and followed by subsequent ultrasound scans. This data can ultimately help determined what percentage the patient has of successfully returning to function and sport.
All in all, the advent of accurate, high quality, diagnostic musculoskeletal ultrasound in small animal medicine is a state of the art diagnostic advancement essential for a holistic, top notch approach to providing our animal companions the best health care available.