WITHERS FRACTURE - Frattura del garrese nel cavallo: review bibliografica
In field condition only latero-lateral views can be acquired (Butler et al., 2008) as the withers is difficult to image because of different thickness: the summits of the DSPs are thinner when compared with distal portions of the DSPs and this makes xray acquisition parametres difficult to set. A radiopaque marker should have been used to identify DSPs. Withers is the most dorsal point of the back, formed by the DSPs of T4–T7 (Graham et al., 2015). In Piat et al.’s study (2012) withers fractures were usually present in three (as in this patient) or more dorsal spinous processes, with a median number of affected DSPs of 6.5 (range 2-7).
The sixth DSP is reported to be the highest (Barone, 1989 and Butler et al., 2017), sometimes the tallest one can be the seventh (Barone, 1989; Butler et al., 2017). For this anatomical reason the sixth spinous process was fractured in 85.7% of horses (Piat et al., 2012). Separate centres of ossification of the spinous processes can be fractured too. The frequency of injury decreases with the height of the spinous process and 98.7% of the fractures were complete, mostly simple (73.7%) and transverse (90% of the simple fractures) (Piat et al., 2012). The dorsal third of the dorsal spinous process is the most commonly injured (65.8%) (Piat et al., 2012), as the dorsal third of the DSPs becomes thinner and narrower and so it structurally weaker (Barone, 1989; Piat et al., 2012). Fracture of the dorsal spinous processes is usually associated to a traumatic event, that affects the horse’s ability to train and race (Fürst, 2019). There are little information about short-term treatment and long-term outcomes for elite racing horse, but the median time between injury and return to race is 6 (Graham et al., 2015) up to 9 months (Molnar et al., 2012; Piat et al., 2012). In Graham et al.’s study (2015) all horses returned to their previous or higher level of performance after injury. Conservative treatment is usually successful in most patients although surgical intervention may be necessary in case of bone sequestrum, severe withers deformity or open fractures (Gustilo and Anderson, 1979; Gustilo et al., 1984; Jeffcott and Haussler 2004; Perkins et al. 2005; Driver and Pilsworth 2009; Fürst, 2019). The prognosis for sportive return is good, although a depression or chronic thickening may persist at the level of the withers (Jeffcott 1999), with impingement of the saddle on the withers and so additional padding may be recommended (Fürst, 2019).
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· Barone, R. (1989) Anatomie comparée des Mammifères domestiques Arthrologie et Myologie, Vigot, Paris. pp 363-377.
· Butler JA., Colles, C.M., Dyson, S.J., et al. (2008) General principles. In: Clinical radiology of the horse. 3rd e. E. Blackwell Scientific Publications.: p. 8
· Butler, J.A (2017) The vertebral column. In: Butler, J.A., Colles, C.M., Dyson, S.J., Kold, S.E., Poulos, P.W. “Clinical Radiology of the Horse” Ch.12. 4rd ed. Mississauga, Ontario: Wiley: pp.531-607.
· Driver, A. and Pilsworth, R. (2009) Traumatic damage to the back and pelvis. In: Equine Back Pathology: Diagnosis and Treatment, Ed: F.M.D. Henson, Wiley-Blackwell, Chichester. pp 135-146.
· Fürst AE (2019) Vertebral Column and Spinal Cord. In: Auer JA, Stick JA, Kummerle and Prange “Equine Surgery”. 5th ed.Ch.53. St. Louis, Missouri: Saunders, pp.864-895
· Jeffcott, L.B. (1999) Diseases of the thoracolumbar region. In: Equine Medicine and Surgery, 5th edn., Eds: P.T. Colahan, I.G. Mayhew, A.M. Merritt and J.N. Moore, Saunders Elsevier, Philadelphia. Pp 1723-1730.
· Jeffcott, L.D. and Haussler, K.K. (2004) Back and Pelvis. In: Equine Sports Medicine and Surgery, 1st edn., Eds: K.W. Hinchcliff and R. Geor, Saunders Elsevier, Philadelphia. pp 433-474.
· Graham R. J. T. Y., Riggs C. M. and Rosanowski S. M. (2015) Retrospective study on the effect of wither fracture on racing performance in Thoroughbred racehorses in Hong Kong (2003 to 2013). Equine vet. Educ. 27 (5) pp. 259-263
· Gustilo, R.B. and Anderson, J.T. (1976) Prevention of infection in the treatment of one thousand and twenty-five open fractures of long bones: retrospective and prospective analyses. J. Bone Joint Surg. Am. 58, pp. 453-458.
· Gustilo, R.B., Mendoza, R. and Williams, D. (1984) Problems in the management of type III (severe) open fractures: a new classification of type III open fractures. J. Trauma 24, pp742-746.
· Molnar, R., Barber, S.M., Pharr, J.W., Panizzi, L. and Plaxton, A. (2012) Healing of multiple fractured thoracic dorsal spinous processes in a Quarter Horse. Can. Vet. J. 53, pp. 279-282.
· Perkins, J.D., Schumacher, J., Kelly, G., Pollock, P. and Harty, M. (2005) Subtotal ostectomy of dorsal spinous processes performed in nine standing horses. Vet. Surg. 34, 625-629.
· Piat P., Blond L., Spriet M., Galuppo L. and Laverty S (2012) Fractures of the withers in horses. Equine vet. Educ. 24 (11) pp. 582-588