Bilateral medial patellar desmotomy in a colt.
Upward fixation of patella (UFP) occurs when the medial patellar ligament becomes caught over the medial trochlear ridge (Stashak, 1987). It is one of the routinely encountered surgical affection in bovines but it is considered to be an infrequent condition in equine patients (Tyagi and Singh, 1996). The condition has been reported to occur more commonly in young horses and ponies and is economically important as it reduces market value of affected animals by 25 to 50%. UFP occurs when the medial patellar ligament (MPL), with its parapatellar fibrocartilage, fails to disengage the notch of medial ridge of femoral trochlea at the commencement of limb flexion. The affected limb cannot be flexed and the horse assumes a posture in which the affected limb is extended in a caudally abducted position (Stashak, 1987). Impaired patellar function is characterized by jerky movements to complete immobilization of joint during flexion (Tyagi and Singh, 1996). It is generally considered that there may be a hereditary predisposition to upward fixation of patella (Adams, 1976).
A Non-descript colt aged 14 months was referred with history of bilateral locking of hind limbs in extension (Fig. 1). Clinical examination of animal during walking revealed locking of both the hind limbs during movement, dragging of toe along the ground and subsequent hyperflexion of stifle. Hence, the case was diagnosed as intermittent bilateral upward displacement of patella and medial patellar desmotomy was planned accordingly.
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The animal was kept off fed for 24 hours and water was withheld for 12 hours. The animal was sedated with Xylazine @ 1.1mg/kg IV (Xylaxin (a)). The animal was restrained in right lateral recumbency and the area over the middle and medial patellar ligaments was clipped and prepared aseptically for surgery. Lignocaine 2% solution (Xylocaine (b)) was injected subcutaneously over the middle and medial patellar ligaments using a 22 gauge needle. After careful palpation of the ligament to be resected, a stab incision was made 1.5 inch above the insertion of the medial patellar ligament on the tibial tuberosity and 1.5 inch medial to medial patellar ligament (Fig. 2). Desmotomy was performed using B.P. blade No. 12 with the cutting edge of the blade against the ligament (Fig. 3). A definite cavity was felt with the fore finger after the surgical procedure was completed. The skin was opposed with two simple interrupted sutures using nylon. A similar surgical procedure was carried out on the contralateral limb (Fig.4 and 5). A prophylactic dose of tetanus toxoid was administered after completion of the surgical procedure.
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Post-operatively, the animal was administered with broad spectrum antibiotics Ceftriaxone @ 10 mg/ kg IV (Intacef (c)) for 5 days and analgesic Meloxicam @ 0.5mg/kg IM (Melonex (c)) for 3 days. The wound was dressed daily with 5% povidone iodine solution (Betadine (d)) and a fly repellent spray (D'Mag (c)) was also applied twice daily.
The animal showed immediate signs of recovery soon after the surgery and the locking of limbs disappeared in the post-operative period (Fig. 6). Recurrence was not reported for a follow up period of 6 months.
Horses with straight limb conformation were more susceptible to upward fixation of patella than horses with normal conformation (Tribar, 2002). The femoro tibial angle in most horses in approximately 135[degrees] and the problem occurs when the angle reaches 145[degrees] (Rooney, 1973). The hyperextension of limb is exacerbated by walking a horse downhill.
The condition also appears when the medial patellar ligament has a reason to become long enough to reach over the medial trochlear ridge despite normal hind limb conformation. The lengthening of medial patellar ligament has been reported to occur in clinical conditions of loss of quadriceps muscle tone and traumatic hyperextension of the hind limb (Noorie, 1982). The condition needs to be differentiated from string halt in horses as in upward fixation of patella, the limb is locked in extension and extended caudally and bit laterally while in string halt the horse hyperflexes the limb with exaggerated upward motion of affected hind limb but the downward motion of limb is normal (Stashak, 1987).
Various physiotherapeutic modalities have also been employed for the treatment of this condition. However in animals not responding to these physical therapies, a medial patellar desmotomy is required (Stashak, 1987).
Medial patellar desmotomy is a common treatment for intermittent upward fixation of patella in cattle and horses in cases unresponsive to conservative management and in severe cases (Stashak, 1987; Greenough et al., 1972). Following medial patellar desmotomy, healing of the medial patellar ligament occurs and the ligament becomes thickened throughout its entire length. The thickened medial patellar ligament is therefore allowed to disengage easily the notch of the medial ridge of the femoral trochlea at the commencement of limb flexion and upward fixation of patella is prevented. Splitting of the proximal third of the medial patellar ligament had also been described as an effective treatment of upward fixation of patella (Tribar, 2002).
Surgery is essential for the treatment of this condition which does not respond to other therapeutic modalities as secondary complications may occur if delay in performing surgery is done (Clegg and Butson, 1996). The surgical procedure is easy to perform and in most cases, the results are visible immediately post-operatively. However, failure of medial patellar desmotomy to correct the problem has also been reported when the persisting medial patellar ligament tissue still displaces over the medial trochlear ridge. An alternative procedure has been suggested in which the accessory cartilage of patella is transacted close to the ligamentous tissue but the outcome of this technique has not been evaluated (Hickman, 1964).
Adams, O. R. (1976). Upward fixation of the patella. In: Lameness in Horses. 3rd Edn., Lea & Febiger, Philadelphia. pp 304-308.
Clegg, P. D. and Butson, R. J. (1996). Treatment of a coxofemoral luxation secondary to upward fixation of the patella in a Shetland pony. Vet Rec. 138: 134-37.
Greenough, P. R., MacCallum, F. J and Weaver, A. D. (1972). Patellar luxation. In: Lameness in Cattle. J. B. Lippincot Company, Philadelphia. pp 260-63.
Hickman, J. (1964). Upward retention of the patella in the horse. Vet. Rec. 76: 1198-99.
Norrie, R.D. (1982). Diseases of rear leg. In: Equine Medicine and Surgery, Mansmann, R.A. and McAllister, E. S. (Eds). American Veterianry Publications, Santa Barbara. p. 1137.
Rooney, J.R. (1973). The abnormal rear leg. In: The Lame Horse, South Brunswick, Bew Jersey. p. 175.
Stashak, T.S. (1987). Upward patellar fixation. In: Adam's Lameness in Horses, 4th edn.Lea & Febiger, Philadelphia. pp 737-741.
Tribar, M.A. (2002). Medial patellar ligament splitting for the treatment of upward fixation of the patella in 7 equids. Vet Surg. 31: 462-67.
Tyagi, R.P.S. and Singh, J. (1996). Ruminant Surgery. 2nd edn. CBS Publishers and Distributors, New Delhi.
D.N. Madhu (1), S.W. Monsang (2), Jasmeet Singh (3), A.M. Pawde (4)
Division of Surgery Indian Veterinary Research Institute Izatnagar Bareilly--243122 (Uttar Pradesh)
(1) Ph.D. Scholar and Corresponding Author
(2) Ph.D. Scholar
(3) Assistant Professor, Dept. of Veterinary Surgery and Radiology, CVSc. & A.H., OUAT, Bhubaneswar
(4) Principal Scientist
(a)--Brand of Indian Immunologicals Ltd., Hyderabad
(b)--Brand of Astra Zeneca Pharma Ltd., Bengaluru
(c)--Brand of Intas Animal Health, Ahmedabad
(d)--Brand of Win Medicare Ltd., New Delhi
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|Title Annotation:||Short Communication|
|Author:||Madhu, D.N.; Monsang, S.W.; Singh, Jasmeet; Pawde, A.M.|
|Date:||Jul 1, 2012|
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