Purpose: Intraoperative frozen section analysis in which the number of cells per high powered field (CPHF) are used to predict the presence or absence of infection has been found to be a very useful test in the setting of revision total joint arthroplasty. The purpose of this retrospective review was to determine the usefulness of this same test at the time of implantation of a total hip arthroplasty (THA) following the failure of hip fracture fixation.

Method: A retrospective review from 1999 – 2007 of twenty-two consecutive patients who had THA performed as a result of failed hip fracture fixation. The mean age of patients was seventy-two years. The number of CPHF was correlated with the results of intraoperative cultures, and other pre-operative and post-operative parameters. The mean duration of follow-up was 14 months.

Results: Two patients had a culture-proven infection (Staphylococcus aureus in one patient, and staphylococcus epidermidis and propionibacterium acnes in the other.) Both of these patients had a positive test for infection based on the frozen section having greater than ten CPHF by the pathologist. (100% agreement) Four out of the six specimens that were graded as 10 CPHF by the pathologist had negative intra-operative cultures (33% agreement). With the CPHF limit set at 10 CPHF, the sensitivity of frozen section analysis in this clinical setting was 100%, while the specificity was 19%. The positive predictive value was calculated to be 33%, and the negative predictive value was 100%. With the cutoff of 5 CPHF or greater, the sensitivity of 100% and a specificity of 52% as well as a positive predictive value of 17% and a negative predictive value of 100%.

Conclusion: Although the results are preliminary, and further study is warranted, it seems that CPHF is a useful test to rule out the presence of infection when revising failed fracture fixation to Total Hip Replacement..

Fresh frozen allograft bone was used to fill defects during revision total knee replacements in 21 patients (21 knees) using radial impaction grafting technique. Radial Impaction grafting technique produces a very rigid bone cement construct to allow for immediate weight bearing without any reinforcements. The strength of the graft substitute with stems allowed us to avoid metal augments in both type II and type III defects in majority of cases. At a minimum of 12 months follow up (12 to 60 months follow up, average 28 months), 19 of the knees showed radiological incorporation of the graft and no evidence of lysis of bone graft. Radiological incorporation of the graft was seen as early as six months and remodelling was continuing at three years. There were no cases of non-union. There were no cases of collapse of the graft or migration of the implant. There was one cases of osteolysis due to deep infection, which needed re-operation. There was one case of traumatic peri-prosthetic fracture, which was treated conservatively.

Oxford knee scores improved from an average of 45 (35 to 53) to 17.4 (12 to 22) at an average follow up of 27.4 months. American Knee Society scores improved from an average of 39.8 (31 to 53) to 87.8 (30 to 70). Knee Society Function scores improved from an average of 45 (30 to 70) to 85 (65 to 100) at last follow-up.

We recommend use of radial impaction grafting technique to fill defects of type II and type III in Tibias during revision knee arthroplasty.

1. Articular cartilage from immature rabbits was placed in and near the rabbit knee joints for periods up to ten weeks.

2. Autografts of articular cartilage when placed free in the joint soon became adherent to its synovial lining; the cartilage with its subchondral bone remained viable.

3. Homografts remained viable in the presence of joint fluid, but when in contact with synovium antigenic cellular reaction was produced early. The presence of subchondral bone intensified this reaction and led to graft invasion and destruction.

4. Partial thickness homografts of articular cartilage were also antigenic and were absorbed. When full thickness cartilage was used, this cellular invasion was resisted by the zone of provisional calcification which appeared to function as a physical barrier against antigenic cells of the host.

5. When placed in muscle, both autogenous and homogenous grafts failed to survive through lack of nutrition, although the autogenous subchondral bone remained viable. It is inferred that subchondral circulation is not sufficient for cartilage survival and synovial fluid is essential for its proper nutrition.

6. Surviving immature articular cartilage transplants underwent "ageing" changes.