Background:

Nowadays, many different techniques have been used to treat cranial cruciate ligament rupture (CrCL) in dogs, being the most common ones the tibial tuberosity advancement (TTA) and the tibial plateau leveling osteotomy (TPLO). These procedures promote dynamic stabilization. In other words, they try to stabilize the knee while supporting the limb, decreasing the cranial tibial impulse, which anticipates the function's return. Among the complications observed in these kind of osteotomy, stand out the osteomyelitis, with 7,3% requency in TPLO and 6,6% in TTA. In these cases, it is necessary to remove all the implants. Most bone infections are from bacterial source, mostly caused by Staphylococcus genus. The aim of this study was to describe 14 cases of osteomyelitis in dogs after CrCL rupture corrective osteotomy. Materials, Methods &

Results:

This retrospective study evaluated 89 dogs (104 knees) that had undergone any of the CCLR corrective osteotomy during the period of January 2006 to November 2012. These patients were divided in TTA (n = 56), TPLO (n = 36) or CWO (closing wedge osteotomy) (n = 12). Among the 104 knees, 14 developed osteomyelitis as postoperative complication, requiring the removal of the implants. The clinical signs observed in these patients were claudication (different degrees), pain in the area of the implants, swelling and local temperature increase. When the osteotomy line was consolidated and the radiological signs of osteomyelitis were identifi ed, the implants were removed and sent to bacterial culture and antimicrobial sensibility test before an antimicrobial therapy was instituted. However, if bone consolidation was not complete, an empirical therapy based on amoxicillin associated with clavulanic acid was performed, with treatment length according to the case. Fourteen animals where evaluated (6 males and 8 females). The average age and weight where 3,7yr and 46,59 kg. The technique chosen was TTA in 7 patients, TPLO in 6 dogs and CWO in just one animal. The mean period for implants removal was 240,5 days. The osteomyelitis rate was 13,46% against all the osteotomies (12,5% of the TTA, 16,6% of TPLO and 8,3% of CWO). Nineteen bacterial cultures were performed (3 bones biopsy and 16 implants - 14 plates and 2 cages), isolating coagulase-positive Staphylococci (n = 8), coagulase-negative Staphylococci (n = 4), Staphylococcus intermedius (n = 2 ), Streptococcus sp. (n = 1), Pseudomonas spp. (n = 2), Hafnia alvei (n = 1) and 3 samples with no bacterial growth.

Discussion:

There were performed 19 bacterial cultures; among these, the most frequent microorganisms isolated were the Staphylococcus genus. These bacteria occur as commensals in dogs' skin and mucosa, but sometimes can act as opportunist pathogens, causing pyogenic infection, once small traumas and immunodepression can predispose to infection development. The coagulase enzyme production is an important indicator of pathogenicity. The coagulase-positive Staphylococcus, resistant to innumerous antimicrobials drugs, are responsible for most infections. The high rates of osteomyelitis found in CrCL rupture osteotomies emphasize the importance of rational use of antimicrobials drugs, as well as the importance of performing bacterial culture and antimicrobial sensitivity from implants or bone fragments, in order to guarantee appropriate antimicrobial therapy in case of bone infections.