Treatment of recurrent luxation of the shoulder in an ...

Short Communications Treatment of recurrent luxation of the shoulder in an alpaca

D GT SS BT

J. M. Vandeweerd, P. Clegg, E. Wawra, A. Dugdale LUXATION of the shoulder is an uncommon condition in large animals (Semevolos and others 1998), and has not previously been reported in alpacas. Alpacas are raised primarily as companion animals, and have similar orthopaedic problems to cattle. The mild temperament and relatively small body size of these animals make them excellent candidates for the treatment of orthopaedic problems (Kaneps 1996). This short communication describes the clinical presentation and surgical treatment of recurrent lateral luxation of the shoulder in an alpaca by greater tubercle osteotomy and bicipital tendon transposition, using a technique previously described in dogs (Hohn and others 1971, Piermattei 1997, Engen 1998, Talcott and Vasseur 2003). A four-year-old male alpaca, bodyweight 60 kg, had a history of recurrent luxation of the shoulder. The initial luxation had occurred seven months previously, after a fight with another male alpaca. The luxated joint was easily reduced under sedation using 6 mg (0·1 mg/kg) xylazine (Rompun; Bayer), and the animal was reported be sound between each episode. On examination, the alpaca did not show any lameness at the walk, and manipulation of the shoulder was not resented in extension or flexion. There was no swelling or thickening of the soft tissues. Lateral luxation was easily induced manually, resulting in a non-weight-bearing lameness, but any luxation could be easily reduced without sedation. Craniocaudal and lateromedial radiographs of the shoulder were taken in sternal and lateral recumbency, respectively. There were no visible osteoarthritic or other changes affecting the shoulder joint with the joint reduced. The alpaca was not allowed food for 24 hours before surgery, and water was withheld for at least eight hours. After placement of a 14 G catheter into the right jugular vein (Intraflon 2; Vygon), 6 mg xylazine was administered intravenously to sedate the animal. Anaesthesia was induced with 140 mg (2·3 mg/kg) ketamine (Ketaset; Fort Dodge Animal Health) and 5 mg (0·08 mg/kg) diazepam (Diazepam; Hameln Pharmaceuticals), administered intravenously. The alpaca became recumbent, but needed additional increments of ketamine, as well as the local application of lidocaine (Xylocaine Spray; Astra) on to the larynx, to facilitate intubation of the trachea using a cuffed endotracheal tube with an internal diameter of 7·5 mm. Anaesthesia was maintained with sevoflurane (SevoFlo; Abbott) in 100 per cent oxygen, administered via a small animal circle breathing system. Flunixin (60 mg) (Meflosyl; Fort Dodge Animal Health) and 6 mg morphine (Morphine Sulfate; Celltech) were administered before surgery to provide analgesia. The animal received 10 ml/kg/hour Hartmann’s solution intravenously throughout the period of anaesthesia. The alpaca was positioned in right lateral recumbency. After the usual aseptic precautions, a craniolateral parahumeral incision was made, beginning 6 cm dorsal to the shoulder joint and extending to a point midway down the humeral shaft. The skin and subcutaneous tissues were then reflected, and the lateral border of the brachiocephalic muscle was retracted medially, exposing the cranial aspect of the proximal humerus and the insertions of the supraspinatus, deltoid and superficial and deep pectoral muscles (Fig 1).

BC

FIG 1: Craniolateral view of the shoulder of an alpaca, showing the bicipital tendon (BT), the greater tubercle (GT), the insertion of the supraspinatus muscle (SS), the brachiocephalic muscle (BC) retracted medially and the deltoid muscle (D)

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FIG 2: Bone flap (BF) from the greater tubercle (GT), created with an oscillating saw. The gliding holes (GH) are also visible

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The insertion of the superficial pectoral muscle was transected. The tissues over the bicipital groove and the intertubercular ligament were incised. The biceps tendon was freed from the surrounding fascia by blunt dissection proximally, and the muscle body was separated from surrounding tissue distally. Two holes were drilled through the greater tubercle, 1·5 cm apart, using a 2 mm drill bit perpendicular to the humerus axis, exiting on its medioproximal aspect. The gliding holes were enlarged with a 3·5 drill bit to a depth of 1·5 cm. The pilot hole was drilled with a 2·5 mm drill bit through the opposite cortex. A depth gauge was used to obtain the correct length of screw before tapping the pilot hole with a 3·5 tap. Two 3·5 mm cortical screws, 4·8 and 5·5 cm long, were driven in place to assess correct positioning and length, and they then were removed. A 7 mm thick osseous flap, 2·5 cm long and 1·5 cm wide, was made with an oscillating saw from the greater tubercle, to include the insertion of the supraspinatus muscle. The flap was retracted and separated proximally from the surrounding tissues by blunt dissection (Fig 2).The bicipital tendon was transposed laterally and the bone flap from the greater tubercle was fixed in position with the screws (Fig 3). The wound was flushed with saline. The brachiocephalic muscle was reattached and the subcutaneous tissues were closed in a simple continuous pattern with 2·0 braided lactomer (Polysorb 2.0; Syneture). The skin was closed with simple interrupted sutures of polypropylene (Prolene 0; Ethicon). A stent bandage was applied on the skin. The alpaca was placed into sternal recumbency with its head held up and blankets were used to treat the hypothermia (rectal temperature 35·7°C at the end of the procedure). The endotracheal tube was removed once the animal’s swallowing reflex returned, but the head was kept supported in an elevated position until full consciousness was achieved. A moderate bloat developed during the procedure, but it resolved once the animal was placed into sternal recumbency and no reflux was observed. A dose of 6 mg morphine intramuscularly, followed by 0·6 mg (0·01 mg/kg) buprenorThe Veterinary Record, March 3, 2007

Veterinary Record (2007) 160, 304-306 J. M. Vandeweerd, DMV, MEd, CertES(Soft Tissue), MRCVS, P. Clegg, MA, VetMB, CertEO, DipECVS, MRCVS, E. Wawra, MagMedVet, MRCVS, A. Dugdale, MA, VetMB, DVA, DipECVA, MRCVS, Department of Veterinary Clinical Science and Animal Husbandry, University of Liverpool, Leahurst, Neston, Cheshire CH64 7TE

Short Communications

BT LS

FIG 3: Greater tubercle with the insertion of the supraspinatus muscle (SS) stabilised with two lag screws (LS). The bicipital tendon (BT) is also shown

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phine (Vetergesic; Alstoe) intramuscularly and 60 mg flunixin intravenously, provided the animal with further analgesia. After recovery, the limb was placed in flexion in a sling. Postoperative care consisted of administration of 120 mg (2 mg/kg) ceftiofur (Excenel; Pharmacia) and 130 mg (2·2 mg/kg) ketoprofen (Ketofen; Merial) once daily for three days. The stent bandage was left in place for two days and the skin sutures were removed after 12 days. The alpaca was kept inside in a herd of males for three weeks and the sling was changed every four days. After three weeks, the sling was removed. Physiotherapy was undertaken, which included stretching and manipulation of the limb. The alpaca was lame (score 4 out of 10) for three weeks, but after that it improved significantly and was turned out for a period of time every day from that point. Seven months after the surgery, the alpaca was sound and no further luxation had been reported. Shoulder luxation is stated to be uncommon in the dog (Vaughan 1967, Hohn and others 1971, De Angelis 1975, Vasseur 1983); it is also rare in large animals. In a retrospective study of luxation of the shoulder in large animals over a period of 21 years, Semevolos and others (1998) identified 14 cases, including five horses, three goats, one calf, one sheep, one Himalayan tahr (Hemitragus jemlahicus), one pot-bellied pig, one reindeer (Rangifer tarandus), and one white-tailed deer (Odocoileus virginianus). The prevalence was high in young animals (over one year old) and sexually intact males, possibly because young animals tend to be very active and may have a poorly developed musculature, and males are especially active and are more likely to be involved in fighting behaviour that would result in that injury (Semevolos and others 1998). Luxation of the scapulohumeral joint has been seen in ponies more frequently than in horses (Dyson 2003). The occurrence of shoulder luxation and its treatment have not been reported in alpacas. The present case was a young adult with normal conformation and well-developed musculature; the injury had occurred during a fight with one of the group of males in which it was kept. The causes of luxation can be categorised as traumatic or congenital. Congenital dislocation has been recognised in the dog, in miniature poodles (Vaughan 1969). Dysplasia of the scapulohumeral joint has been identified in Shetland ponies (Boswell and others 1999) and miniature horses (Dyson 2003), sometimes associated with subluxation of the joint or with osteoarthritis (Clegg and others 2001). Luxation of the shoulder may be medial or lateral, cranial or caudal. The percentage of animals with cranial luxations appears to be higher in large animals (Semevolos and others 1998). The mechanism of lateral luxation is undetermined but presumably results from extreme adduction of the limb. Patients with lateral scapulohumeral luxation carry the affected limb in flexion and often with internal rotation of the foot. The greater tubercle is prominent and displaced laterally relative to the acromion (Talcott and Vasseur 2003). The Veterinary Record, March 3, 2007

In addition to complete luxation, animals may have acquired subluxation. This results from trauma that is sufficient to create joint instability but not enough to result in total luxation. Subluxation often leads to chronic instability, degenerative arthritis and progressive disuse. In recurrent medial or lateral shoulder luxation, the joint will undergo luxation and spontaneous reduction many times a day. An examiner can frequently relocate the shoulder without anaesthesia or any obvious discomfort (Newton 1985). Recurrent luxation has not been described in the alpaca. In the present case, no lameness was noticed between the episodes. However, reduction was not spontaneous and required a veterinary surgeon’s intervention. Sedation was used initially but then became unnecessary. Different surgical techniques have been described in small animals for treatment of traumatic lateral luxation of the shoulder, including distal transposition of the greater tubercle and tension of the supraspinatus muscle (Hinko 1977), intra-articular implants of nylon or steel wire (Vaughan 1975), stabilisation with prosthetics such as large sutures, polypropylene meshes or stainless steel wires (Engen 1998), and bicipital tendon transposition after greater tubercle osteotomy (Hohn and others 1971, Piermattei 1997, Engen 1998, Talcott and Vasseur 2003), which appears to be the preferred and best documented technique for lateral joint stabilisation. The transposition of the bicipital tendon technique has been attempted in shoulder luxations in large animals (Semevolos and others 1998) but has not been reported in alpacas. Even though few procedures have been described in the camelid literature, many procedures can be performed utilising techniques described in standard surgical textbooks for horses, cattle and dogs (Fowler 1998). Owing to the small number of cases, no study is available to influence the choice of technique in large animals. The prosthetic technique in small animals relies solely on sutures for support, and it is essential to use external immobilisation for two to three weeks to prevent the sutures from cutting out of the tightened tissue (Newton 1985). Stainless steel wires may often break and have to be removed if they cause pain or lameness (Engen 1998). The prosthesis might not be strong enough in heavy animals. Transposition of the bicipital tendon was therefore considered to be the most appropriate technique in this case, provided the mobility of the bicipital tendon and its possible lateral retraction could be assessed at surgery, and the ability to fix the greater tubercle strongly enough with 3·5 screws after osteotomy. At the beginning of surgery, the bicipital tendon was easily retracted laterally. A long surgical incision and extensive blunt dissection was necessary to mobilise the bicipital tendon and muscle and allow lateral transposition. Incision of the joint capsule described elsewhere (Hohn 1971, Engen 1998, Semevolos and others 1998) did not appear necessary in this case to mobilise the bicipital tendon from the intertubercular groove sufficiently. The size of the bone fragment appeared to be compatible with the use of 3·5 lag screws. The preparation of the holes and threads before the osteotomy made fixation easy. Lag screws were used instead of the Palmer-Stille nails or Kirschner wires used in small animals. The technique ensured excellent stability and strength, which is an important factor in heavy animals.

References BOSWELL, J. C., SCHRAMME, M. C., WILSON, A. M. & MAY, S. A. (1999) Radiological study to evaluate suspected scapulohumeral joint dysplasia in Shetland ponies. Equine Veterinary Journal 31, 510-514 CLEGG, P. D., DYSON, S. J., SUMMERHAYS, G. E. & SCHRAMME, M. C. (2001) Scapulohumeral osteoarthritis in 20 Shetland ponies, miniature horses and falabella ponies. Veterinary Record 148, 175-179 DE ANGELIS, M. P. (1975) Luxation of the shoulder. In Current Techniques in

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Small Animal Surgery. Ed D. Slatter. Philadelphia, Lea & Febiger. p 499 DYSON, S. J. (2003) The elbow, brachium and shoulder. In Diagnosis and Management of Lameness in the Horse. Eds M. W. Ross, S. J. Dyson. Philadelphia, Saunders. pp 410-414 ENGEN, M. H. (1998) Surgical fixation of shoulder luxations. In Current Techniques in Small Animal Surgery. 4th edn. Eds M. J. Bojrab. Baltimore, Williams & Wilkins. pp 1074-1081 FOWLER, M. E. (1998) Surgery. In Medicine and Surgery of South American Camelids. Ed M. E. Fowler. Ames, Iowa State University Press. pp 140-146 HINKO, P. J. (1977) Recurrent shoulder luxation. Canine Practice February, 46 HOHN, R. B., ROSEN, H., BOHNING, R. H., Jr & BROWN, S. G. (1971) Surgical stabilization of recurrent shoulder luxation. Veterinary Clinics of North America: Small Animal Practice 1, 537-548 KANEPS, A. J. (1996) Orthopedic conditions of small ruminants. Llama, sheep, goat, and deer. Veterinary Clinics of North America: Food Animal Practice 12, 211-231 NEWTON, C. D. (1985) Dislocation of the shoulder. In Textbook of Small Animal Orthopaedics. Eds C. D. Newton, D. M. Nunamaker. Ithaca, International Veterinary Information Service. www.ivis.org/special_books/

ortho/chapter_21/21mast.asp. Accessed June 10, 2005 PIERMATTEI, D. (1997) The shoulder joint. In Brinker, Piermattei, and Flo’s Handbook of Small Animal Orthopaedics and Fracture Repair. Ed D. Piermattei. Philadelphia, W. B. Saunders. pp 230-241 SEMEVOLOS, S. A., NIXON, A. J., GOODRICH, L. R. & DUCHARME, N. G. (1998) Shoulder joint luxation in large animals: 14 cases (1976-1997). Journal of the American Veterinary Medical Association 213, 1608-1611 TALCOTT, K. W. & VASSEUR, P. B. (2003) Luxation of the scapulohumeral joint. In Textbook of Small Animal Surgery. 3rd edn. Ed D. Slatter. Philadelphia, W. B. Saunders. pp 1897-1903 VASSEUR, P. B. (1983) Clinical results of surgical correction of shoulder luxation in dogs. Journal of the American Veterinary Medical Association 182, 503-505 VAUGHAN, L. C. (1967) Dislocation of the shoulder joint in cats and dogs. Journal of Small Animal Practice 8, 45 VAUGHAN, L. C. (1969) Congenital dislocation of the shoulder joint in the dog. Journal of Small Animal Practice 10, 1-3 VAUGHAN, L. C. (1975) Dislocation of the shoulder joint in dogs. Proceedings of the XI Congress of the European Society of Veterinary Surgery. Copenhagen, Denmark, May 7 to 11, 1975. pp 5-8

The Veterinary Record, March 3, 2007