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EQUINE VETERINARY EDUCATION / AE / JANUARY 2017
Fig 5: Vacuum assisted closure system in place – horse able to ambulate and lay down.
repeated for the third time. At this point the joint was still visibly inflamed, the synovial membrane was oedematous and fibrin was present in the joint. The joint was lavaged, fibrin and debris debrided using a motorised synovial resector, the wound was debrided once more using ultrasound assisted wound therapy and the horse recovered in a splint bandage, since recovery with the VAC system in place would have been an increased risk for the horse and the therapy unit. Two days later the VAC therapy was reinstituted (16 days post admission). Four days after the third arthroscopic lavage (18 days post admission) the horse was fully weightbearing, and the defect had subjectively decreased in size by approximately 25% and had filled with smooth, healthy appearing granulation tissue with little exudate. Distention with sterile saline revealed a lack of communication between the wound and the antebrachiocarpal joint. Analgesic therapy was reduced by half for 2 days post surgery then stopped and the horse’s comfort level was unchanged. Systemic antimicrobial therapy following the culture and sensitivity results was performed for a total of 20 days and stopped when the fistula was confirmed to be closed. After a total of 12 days’ VAC therapy, including one
interruption for continued arthroscopic treatment, the wound was completely filled with smooth granulation tissue, surrounded by an approximately 0.5 cm circular epithelial margin, and demonstrated a small amount of serosaguinous exudation (Fig 6). At this point the VAC therapy was discontinued and replaced by a hydrocolloid (Nobacolloid)11 dressing to keep the wound moist. The limb was bandaged using a double layer full-limb bandage, which was changed every 3 days. Fourteen days later, the wound was almost completely epithelialised and the stallion was not lame at the walk (Fig 7). Radiographs taken showed an increase new bone formation on the distal radius, the proximal carpal bones, and a marked soft tissue swelling consistent with chronic inflammation and osteoarthritis secondary to joint sepsis. Based on the clinical improvement of the horse, resolution of the septic osteoarthritis, and closure of the fistula the horse was discharged from the hospital, without any medical treatment but a further 2 months of stall rest before re-evaluation by the referring veterinarian. On telephone follow-up one month after hospital discharge, the stallion was still sound at walk.
© 2015 EVJ Ltd
Fig 6: The wound after a total of 12 days vacuum assisted closure therapy, almost completely filled with smooth granulation tissue.
Fig 7: The horse at the time of discharge. Discussion
Chronic septic osteoarthritis with a synovial fistula in the presence of multiresistant microorganisms carries a poor prognosis. Infected wounds are more complicated to treat, due to the reduced wound tensile strength, an undesirable inflammatory response and impediment of the healing process by bacterial damage to the tissue (Gabriel et al. 2009). In this case, surgical wound management, including aggressive debridement of infected and necrotic tissue, arthroscopic assisted lavage, immobilisation of the wound, and systemic and local application of antimicrobials alone did not resolve the joint infection. Typically septic osteoarthritis fails to resolve if treated inadequately or if infected cartilage, subchondral bone, or fibrinous debris harbours infectious organisms, which continue to precipitate the infection (Schneider et al. 1992). On the radiographic images obtained on Day 1, there were no signs of osteomyelitis, and, during the 3 arthroscopic surgeries performed, we only found one small cartilage defect, which was debrided, but solid subchondral bone and no evidence for osteomyelitis making an intra-articular source of reinfection less likely. The subcutaneous abscess and the communicating fistula could have been contributing to the continuing septic osteoarthritis which is why aggressive wound therapy was deemed important for resolution of the joint infection. The wound was on the lateral aspect of the joint and a
standard dorsal arthroscopic approach did not give sufficient access to the fistula. Access was only possible by creating a
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