Introduction: Rat-bite fever is an uncommon illness caused by Streptobacillus moniliformis or Spirillum minor. We present an unusual case of rat bite fever involving a left cemented total hip replacement after a rodent bite.

Case report: A 38-year-old lady, presented with poly arthralgia, who had Total Hip replacement for arthritis secondary to developmental dysplasia of Hip(one year ago), presented with signs & symptoms suggestive of infective joint pathology. Examination revealed painful restricted joint movements.

Initial blood tests revealed very high ESR, c-reactive proteins with leucocytosis. Blood cultures were negative. X-rays revealed dislocation of Total hip replacement Ultrasound scan and CT scan revealed a large collection of fluid in the Left Total Hip Replacement.

Aspirate from the affected joints revealed gram negative bacilli, Streptobacillus moniliformis. The joints were all washed out arthroscopically. She was put on intravenous antibiotics and continued for six weeks. The inflammatory markers normalised after six weeks. Follow up x-rays of the left hip prosthesis do reveal some signs of osteolysis and surveillance is ongoing.

Discussion: Prosthetic replacements are now commonplace, with large number of patients keeping pets. Septic arthritis following the rat bite has been reported. As far as we can tell from the available literature that it has not been reported in a joint prosthesis. The long- term outcome is unknown. The possibility of low grade infection involving the joint prosthesis and the association of this organism with endocarditis is a cause for concern.

Does the type of implant have any correlation with critical fusion time of hallux metatarsophalangeal joint? There are few cadaveric biomechanical studies published in the literature assessing the strength and rigidity of different fixation methods. Although it is still unclear whether the amount of metal affects the fusion rate, the aim of this study was to assess whether using a supplementary dorsal ¼ tubular plate in addition to a compression screw gives any added rigidity to the fusion area leading to an earlier fusion.

A retrospective analysis was conducted on the first metatarsophalangeal joint fusion in 26 consecutive patients (34 feet) between April 1998 to February 2002 comparing using single screw versus a screw supplemented with a dorsal ¼ tubular plate. There were 18 females and 8 males with a mean age of 51.5 years and a mean follow-up of 2.9 years. The final fusion was assessed clinically and radiologically by trans-articular trabeculation.

There was a fusion rate of 97%. All patients except one had solid fusion. One case had non-union. Four cases had superficial wound infection, which settled down with appropriate antibiotic therapy. Paraesthesia over the dorso-medial aspect of the big toe in three patients and transfer metatarsalgia in two patients were documented.

The type of implant did not show any direct correlation with the complication rate. There is no evidence to suggest in this study relating the amount of implant to final outcome. Therefore the choice of implant fixation can be at the discretion of the operating surgeon.