Introduction: Two stage revision procedures is the gold standard in management of periprosthetic infections. Cement spacers impregnated with antibiotics have long been used to preserve the space created during resection procedure and to release antiobiotics within the created dead space. However, the problems related to cement as an antibiotic carrier are well recognised (random porosity, thermal necrosis, unspecified antibiotic delivery rate). The rationale of this study is that calcium hydroxyapatite antibiotic carrier (PerOssal) overlaps the known disadvantages of cement spacers, and leads to better outcome in terms of clinical parameters and re-infection rate.

Purpose: Our purpose was to identify specific clinical and laboratory differences between cases submitted to conventional two stage revision arthroplasty vs cases treated with PerOssal as an antibiotic carrier.

Material & Methods: During 2004 to 2008, 46 patients (38 females and 8 males, mean age 65.3 years, range 32 to 84) with infected TKR were revised using a two-stage revision protocol. In 31 patients (group A – 25 females and 6 males) a conventional articulating spacer impregnated with antibiotics was used, whereas in the remaining 15 patients (group B – 13 females, 2 males) a combination of an articulating spacer and PerOssal as antibiotic carrier was used. All patients were reviewed with laboratory exams (WBC, ESR, CRP) every 7 days and joint fluid aspiration prior to re-implantation, which was performed at mean 8 months post 1st stage (range, 6 to 12 months).

Results: At a mean follow-up of 36 months (range, 8 to 60 months) no patient was lost or died. WBC count and ESR showed no statistically significant differences at any time interval (p> 0.05). However, CRP values had a statistically significant difference between the two groups after the second week postoperatively (p3rd week= 0.042) and group B had significantly lower CRP values compared to group A at every check point thereafter (p4th week=0.038, p5th week=0.031, p6th week=0.034). Re-infection rate was 16.12% in group A and 6.6% in group B (p=0.192).

Conclusions: PerOssal can be used as an additional antibiotic carrier in cases of periprosthetic infections of TKR. It is associated with more rapid reduction of CRP levels, probably due to greater porosity and better antibiotic delivery comparing to impregnated cement. Larger series of patients could reveal potential differences in the re-infection rates as indicated by our study.

Between January 1998 and December 1998, 82 consecutive patients (86 hips) underwent total hip arthroplasty using a trabecular metal monoblock acetabular component. All patients had a clinical and radiological follow-up evaluation at six, 12 and 24 weeks, 12 months, and then annually thereafter. On the initial post-operative radiograph 25 hips had a gap between the outer surface of the component and the acetabular host bed which ranged from 1 to 5 mm. All patients were followed up clinically and radiologically for a mean of 7.3 years (7 to 7.5). The 25 hips with the 1 to 5 mm gaps were studied for component migration at two years using the Einzel-Bild-Roentgen-Analyse (EBRA) digital measurement method. At 24 weeks all the post-operative gaps were filled with bone and no acetabular component had migrated. The radiographic outcome of all 86 components showed no radiolucent lines and no evidence of lysis. No acetabular implant was revised. There were no dislocations or other complications. The bridging of the interface gaps (up to 5 mm) by the trabecular metal monoblock acetabular component indicates the strong osteoconductive, and possibly osteoinductive, properties of trabecular metal.