Although there is some clinical evidence of ceramic bearings being associated with a lower infection rate after total hip arthroplasty (THA), available data remains controversial since this surface is usually reserved for young, healthy patients. Therefore, we investigated the influence of five commonly-used biomaterials on the adhesion potential of four biofilm-producing bacteria usually detected in infected THAs.

In this in-vitro research, we evaluated the ability of S. aureus, S. epidermidis ATCC 35984, E. coli ATCC 25922 and P. aeruginosa to adhere to the surface of solid biomaterials, including a 28mm cobalt-chromium metal head, a 28mm fourth-generation ceramic head, a 48mm fourth-generation ceramic insert, a 48mm highly-crossed linked polyethylene insert and a 52mm titanium porous-coated acetabular component. After an initial vortex step, a bacterial separation from the surface of each specimen was done until no remaining attached bacteria were observed by digital optical microscope. The colony-forming units were counted to determine the number of viable adherent bacteria and the bacterial density.

We found no differences on global bacterial adhesion between the different surfaces. E. coli presented the least adherence potential among the analysed pathogens (p<0.001). The combination of E. coli and S. epidermidis generated an antagonist effect over the adherence potential of S. epidermidis individually (58±4% vs. 48±5%; p=0.007). The combination of P. aeruginosa and S. aureus presented a trend to an increased adherence of P. aeruginosa independently, suggesting an agonist effect (71% vs. 62%; p=0.07).

In this study, ceramic bearings appeared not to be related to a lower bacterial adhesion than other biomaterials. However, different adhesive potentials among bacteria may play a major role on infection's inception.

Introduction and purpose: Rhizarthrosis of the thumb is the most common form of osteoarthritis of the hand. In some cases it courses with intense pain and severe functional limitation of the thumb or the entire hand.

The purpose of this study is to compare the results of treating rhizarthrosis with a total ARPE trapezio-metacarpal prosthesis and trapezectomy, whether or not associated with tendon interposition and ligament repair.

Materials and methods: A retrospective comparative study in which we reviewed cases of rhizarthrosis treated surgically in our hospital between 1994 and 2004. We found 75 cases, of which 28 were treated with resection arthroplasty (group A), 32 with ARPE prosthesis (group B) and 15 with bone fusion (not included in this study). The mean age was 58.85 for group A and 63.16 for group B. Mean follow-up time was 39.5 months.

We used the DASH questionnaire for the subjective clinical examination and the Jamar dynamometer for the objective examination. For radiological assessment we used the Eaton classification and Walch radiological criteria.

Results: We analysed the results using SPSS statistical software and found no significant differences between the two groups, although the subjective assessment showed better results in terms of mobility and pain remission in group B and strength in group A.

Conclusions: The aim of surgical treatment of rhizarthrosis is to achieve a stable, pain-free thumb. Several procedures are available, the success of which depends on correct indication and meticulous surgical technique.