Scintigraphy involves the injection of a radioactive substance into the horse. This substance is attached to a calcium salt. Since calcium is preferentially absorbed by sites of active bony change, it accumulates in areas of repairing damage, such as stress fractures. These areas can then be imaged using a gamma camera. It is very useful for detecting damage in areas where nerve blocks cannot be performed, such as the pelvis and neck. Its main limitations are in chromic conditions, where the amount of calcium uptake in an injured area may not be sufficient to be detectable.
Arthroscopy is a type of keyhole surgery which allows us to look inside and treat joint injuries through small incisions, thus limiting the damage created by the surgery itself, and minimising recovery time.
It is used in four main ways:
Chip fracture removal – Small chip fractures are common in racehorses. They cause minimal lameness, but tend to hamper performance at high speeds. They are generally easily removed via arthroscopy, and the horse can be returned quickly to work.
OCD: OCD occurs in the developing weanling, and causes areas of cartilage to detach from the underlying bone. This cartilage causes inflammation and swelling of the joint, leading to lameness. They may be extensive in nature, but lend themselves well to arthroscopic removal, as the scope can be manoeuvred around the joint to seek out and remove all the problem cartilage.
Diagnostic arthroscopy: Sometimes, lameness can be localised to a joint using local anaesthesia, but no bony change can be seen. In this case, the problem is usually soft tissue in nature. This is particularly true in the stifle (the equivalent of the human knee), where sort tissue structures such as the meniscus, cruciate ligaments, and cartilage may all be damaged in areas where x-ray or ultrasound may not be able to highlight them.
Infection: Joint infection was once very difficult to control in horses. Many infections are caused by penetrating wounds. Since the advent of arthroscopy it has become clear that up to half of these joints are contaminated with dirt, hair, or bits of wood. Arthroscopy allows visualisation and removal of this debris, as well as flushing pus from all the nooks and crannies of the joint.