THE USE OF VACUUM DRESSINGS IN INFECTED KNEE REPLACEMENTS

Abstract

Wound breakdown and implant exposure is the most serious complication of total knee arthroplasty. In some patients after removal of the implant, a soft tissue defect remains that is not amenable to closure in any conventional manner as patient co morbidity precludes further major surgery. In addition the risk factors for infection post surgery are the same as those leading to the failure of flap coverage. It is in this group of patients that we have employed the vacuum dressing.

In none of our patients so far has the prosthesis been felt to be amenable for salvage, therefore the first step was a radical debridement of the wound and removal of the prosthesis. Stability of the bone end was then obtained using a Charnley clamp or other external fixator. The vacuum dressing system was inserted and the wound left to heal by granulation. The dressing was changed every 24 to 48 hours depending on wound healing. This resulted in a large amount of healthy granulation tissue and the elimination of residual infection. The resulting wound was then closed either directly or using a split skin graft thereby negating the need for further major surgical interventions.

So far treatment of five patients has been completed. All our patients had significant co morbidity. The mean age was 74 years with a range of 68 to 86 years. These cases were all operated on within six months of their knee replacement. Limb salvage was successful in 4 out of the 5 patients who have completed treatment so far, and these patients have returned to the level of function they had prior to their total knee arthroplasty.

In conclusion, the technique of negative pressure wound dressing and subsequent wound coverage is an effective addition to management options in these difficult cases, and is certainly preferable to amputation.