Purpose: A study was undertaken to determine the current prevalence of revisions of total knee arthroplasty (TKA) following minimal incision surgery (MIS) and to compare revisions of MIS TKA procedures to revisions of TKA performed following a standard surgical approach.

Method: A consecutive series of revision TKA performed at three centers by five surgeons over a three year time period was reviewed. Revisions performed for infection and re-revisions were excluded. Review of clinical and radiographic data determined incision type, gender, age, time to revision, and primary diagnosis at time of revision.

Results: Two hundred and thirty-seven first time revision TKAs were performed of which 44 (18.6%) had been a MIS primary TKA and 193 (81.4%) had been a standard primary TKA. Patients with MIS were younger (62.1 years versus 66.2 years, p=.02). There was a trend towards a higher percentage of females in the MIS group (75% versus 63%), although this difference was not significant (p=0.12). Most striking was the difference in time to revision which was significantly shorter for the MIS group (14.8 months versus 80 months, p< .001). The MIS group was much more likely to fail at < 12 months (37% versus 5%, p< .001) and at < 24 months (81% versus 22%, p< .001).

Conclusion: MIS TKA accounted for a substantial percentage of revision TKA in recent years at these centers. The high prevalence of MIS failures occurring within 24 months is disturbing and warrants further investigation.

Purpose: Prophylactic antibiotics are frequently withheld until cultures are obtained in revision TKA. A prospective study was undertaken to determine whether prophylactic pre-operative IV antibiotics would affect the results of cultures obtained intra-operatively.

Method: A consecutive series of 25 TKA’s with a known infecting organism were enrolled over 36 months. Inclusion criteria: clinically infected TKA, a known preoperative infecting organism, and no recent antibiotic therapy. Re-aspiration of the infected TKA was performed following anesthesia and sterile prep. IV antibiotic prophylaxis was then administered and the tourniquet was then inflated. Intra-operative culture swabs and tissue were obtained at arthrotomy. The timing of events was recorded. Pre/post antibiotic culture data were analyzed to determine the effect of IV preoperative prophylactic antibiotics on cultures obtained intra-operatively.

Results: Mean time from end of antibiotic infusion to tourniquet inflation was 15 minutes; to arthrotomy culture was 25 minutes. In all 25 knees the organism(s) cultured at arthrotomy were the same as obtained at pre-operative aspiration. In 24 knees the organism cultured was sensitive to the preoperative prophylactic antibiotics given (Ancef and Vancomycin); one patient grew Candida albicans.

Conclusion: Pre-operative prophylactic antibiotics did not affect the results of intra-operative cultures, and should not be withheld prior to infected TKA surgery when an organism has been identified on aspiration. Based on these results, holding pre-operative antibiotics prior to revision TKA is rarely justified.

We present the histological findings of an extensor mechanism allograft which was used in a total knee arthroplasty two years after implantation. Analysis of the graft was undertaken at four distinct anatomical levels and it was found to be incorporated into host tissue at each level. A wedge of fibrinoid necrosis, probably related to impingement of the graft on the tibial polyethylene insert, was seen. Impingement may play a role in the injury and necrosis of an allograft and may be one mode of failure in an extensor mechanism allograft.