Treatment of angular limb deformities in foals

Abstract

The sooner a foal's angular conformation is evaluated, the more easily any deformities can be treated. While severely affected foals are likely to require more complex treatment, it may be possible to avoid more radical interventions by tackling problems early on. Practitioners play a vital role in the careful assessment of such deformities to ensure that appropriate management is undertaken before the window of opportunity to make simple manipulations to a foal's angular conformation is lost. The ability to correctly distinguish angular deformities from rotational and flexural deformities is vital. This article describes an approach to the investigation and management of angular limb deformities in foals, and discusses various treatment options, ranging from conservative management to aggressive surgical intervention. Lewis Smith graduated from the Royal Veterinary College in 2006, after which he completed an internship at the Equine Medical Center of Ocala in Florida, USA. He is currently in the third year of a European College of Veterinary Surgeons residency in surgery at Rossdale and Partners in Newmarket. He holds the RCVS certificate in equine surgery (orthopaedics). Aetiology and definitions Angular limb deformities (ALDs) may be placed into two broad categories of differing aetiologies (Witte and Hunt 2009): Perinatal ALDs, which are deformities that can be ■ ■ attributed to either immaturity of the bone structure at birth or some intrinsic failure of the physis to properly develop; Acquired ALDs, which result from disruptions to ■ ■ the process of bone maturation as a foal develops into an adult. Many of the more subtle cases of angular limb deviation are related to acquired rather than perinatal deformities. An ALD is commonly defined as a deviation of the limb from a straight line that bisects the long bones of the limb when viewed from the frontal plane. Deviation towards the lateral aspect is defined as valgus, while dev iat ion towa rd s t he med ia l a spec t is def i ned a s va r us. The angular deviation may either be centred over a single joint, such as the fetlock, carpus or tarsus, or a combination of these. These deviations are distinct from sagittal plane conformational abnormalities or flexural abnormalities causing 'over-at-the-knee' and 'back-atthe-knee' conformation and rotational abnormalities, such as 'toed-out' or 'toed-in' conformation, which involve the long axis of the limb. Line drawings showing (left) straight limb conformation and an approximate deviation of 15° deviation over the fetlock (middle) and carpus (right)

Surgical management of a severe congenital deformity of the hind limb in a Shetland pony foal – a case report

“…This abnormal conformation of the tarsal region led to the lateral projection of the tenaculum of the long and lateral digital extensor tendons, and their displacement to the medial aspect of the bone; the common digital extensor tendon was also displaced to the medioplantar aspect of the limb. Given the severe and complex tarsal limb deformity, surgical management by either transphyseal bridging with staples or wire placed in a figure-eight fashion around two screws, lag-screw technique for transphyseal bridging, or other surgical techniques recommended in the literature (Fretz et al 1978;Witte et al 2004;Auer and von Rechenberg 2006;Witte and Hunt 2009;Smith 2010;McCarrel 2017) were not applicable per se. Osteotomies and ostectomies have been described for the surgical management of ALDs of the MCP/MTP region (Fretz and McIlwraith 1983;Bramlage 1994;Epp 2007).…”

“…stall rest, splits and casts, hoof manipulations), whereas for severe cases a surgical approach should be considered the treatment of choice, based on the appearance and severity level (e.g. growth acceleration and/or retardation, corrective osteotomy/ostectomy) (Auer and von Rechenberg 2006;Bramlage and Auer 2006;Smith 2010;Auer 2012;McCarrel 2017). Assessment of clinical signs and radiographic evaluation are indicated for determining the location, direction, and severity of the deformity (Coleman and Whitfield-Cargile 2017;McCarrel 2017).…”