Last Updated on March 29, 2022 by Allison Price
Proximal Suspensory Desimitis:
The term proximal supensory desmitis (PSD), refers to lesions that are located in the proximal third of the metacarpus. PSD can be unilaterally or bi-directionally. It is common in all types and breeds of horses. Injuries to the proximal supensory ligament or its attachment to third metacarpal bone’s proximal palmar aspect can cause sudden onset lameness. This usually resolves in a matter of days. The severity of lameness can range from mild to moderate, and it is usually not severe unless the ligament is severely damaged or its attachment is broken (avulsion in the palmar cortex). Bilateral PSD may cause more lameness in horses with less obvious signs, but greater loss of movement. Lameness is more apparent on soft ground, with the affected leg at the outside of the circle. Variable responses to distal limb or carpal flexion tests are possible. The proximal palmar metacarpal area may feel pain when pressure is applied. However, it should be compared to the response of the other limb in order to determine its significance.
Diagnostic analgesia is usually required to diagnose PSD. This is because horses rarely have any clinical signs (eg heat, pain, swelling) which would allow lameness to be confined to this area. There are many ways to desensitize proximal palmar metacarpus. Because of the insufficient specificity of local analgesic methods, it can be confusing to interpret subcarpal analgesia results. Radiographs and ultrasonographic examinations of the area should be done after lameness is diagnosed. The proximal suspensory’s ultrasound should be compared to the other limb. Bilateral lesions can also exist. Although nuclear scintigraphy is able to detect osseous injury at proximal supensory attachments, negative scintigraphic images cannot exclude the existence of PSD. Ultrasonography may not show subtle changes, but MRI can detect them. MRI also allows for precise examination of the osseous structures surrounding the suspensory canal (metacarpal bone and distal carpal bone).
Contrary to hindlimb PSD horses with acute forelimb PSD generally respond well to rest and controlled exercise for 3-6 months (90% return of function). Premature return to work typically results in recurrence/persistence of lameness. To return to stable work, horses with chronic PSD may need a longer rehabilitation program, or adjunct therapy (NSAIDs shockwave, regenerative therapies), to get back to their normal routine.
Desmitis of The Body of the Suspensory Liment:
This is a primary injury to racehorses. Most injuries affect Thoroughbreds’ forelimbs, and Standardbreds’ forelimbs. Soreness on palpation of the forelimb suspensory ligament is quite common in horses with lameness associated with a more distal limb problem; however, structural abnormality of the ligaments is only rarely identifiable ultrasonographically. There are many clinical signs that can be seen, including swelling, pain, local heat and swelling. Diagnosis is usually based on clinical signs and can be confirmed ultrasonographically. The treatment is to reduce inflammation using systemic NSAIDs, hydrotherapy and controlled exercise. Suspensory body lesion treatment has also included shockwave therapy, stem-cell therapy, and platelet-rich plasma.
Desmitis of the Branches and the Suspensory Ligament
All types of horses can sustain this injury, forelimbs or hindlimbs. Although usually only one branch is affected in each limb, hindlimbs may have both affected branches. Affected horses often have foot imbalances, which may indicate that this is a contributing factor.
The severity and duration of the lesion(s), as well as the extent of damage, will determine the clinical signs. They may include localized heat or swelling. Local edema can cause swelling in the affected branch. Effusion may also be seen in the adjacent palmar/plantar fitlock joint or the digital flexor tendon. Effusion can be elicited by applying pressure to the injured branch, or by flexion. Lameness can be present or absent.Medial suspensory branches (left and right), ultrasound, horse
COURTESY OF DR. MATTHEW T. BROKKEN.
Ultrasonographic examination and clinical signs are used to diagnose the condition. Radiographic examination is also necessary to determine the location of the suspensory branches attached to the proximal sesamoid bone. A low 4-point diagnostic analgesia and intra-articular painkiller of the fetlock joints (varying degrees depending on the location of branch injuries) can improve lameness. Ultrasonography can detect abnormalities such as enlargement or alteration in shape and changes in echodensity.
The severity of the symptoms and the horse’s breed will determine the management. With varying results, shockwave therapy, local antiinflammatory drugs, ligament splitting, and regeneration therapy were all tried. These lesions can be managed by paying close attention to your foot balance. The improvement in clinical signs can take up to 6 months. It is possible for the condition to recur. Horses with periligamentous or markedly hyperextended fetlocks, or horses with a significant fibrosis around their branch on ultrasound may have a worse prognosis for reinjury and persistence of lameness.