Acute Hematogenous Infection of Revision Total Hip Arthroplasty by Oral\nBacteria in a Patient without a History of Dental Procedures: Case Report
A 53-year old female underwent cup and ball revision of a right THA due to loosening and osteolysis 17 years after primary surgery using a cementless THA (Fig. ). She did not take any corticosteroids and had no history of disease associated with a possibility of infection, such as diabetic mellitus, rheumatoid arthritis, liver cirrhosis, etc.\nNo clinical signs of infection were observed prior to the revision surgery.\nThe laboratory findings included a C-reactive protein (CRP) level of 0.06 mg/dl and a white blood cell (WBC) count of 6,600 cells/μl. The normal value for CRP in the hospital laboratory is a CRP level below 0.3 mg/dl. During the revision surgery, after removing the ball, liner and shell, a cementless porous HA-coated acetabular component and polyethylene liner (AMS-HA acetabular shell and AMS liner; Kyocera, Kyoto, Japan) were implanted. In addition, a new metal ball (C-taper; Stryker, Mahwah, New Jersey, USA) was implanted (Fig. ).\nWith respect to the intraoperative findings, no signs of infection were observed and no specimens obtained intraoperatively for culture at the time of the revision surgery.\nFollowing the revision surgery, the patient was given intravenous cefazolin at the time of induction of anesthesia and for 24 hours postoperatively. She exhibited a routine recovery and showed no symptoms of infection until 18 months after the revision surgery.\nHowever, the patient reported gradually worsening right hip pain. Two weeks later, she visited our institution using a wheelchair. She was febrile (38.7 °C) and had a swollen right thigh with severe pain on motion of the hip joint; however, no fistulas were evidenced. The laboratory findings included a CRP level of 22.3 mg/dl and a WBC count of 5,500 cells/μl. The patient underwent aspiration of the right hip joint for culture; however, no aspirate was obtained.\nTwo-stage revision surgery was planned to treat the infected THA.\nThe patient underwent removal of the entire THA implant. There was pus in the capsule, and cup loosening was found. The patient underwent debridement of the area around the abscess in an effort to prevent progression of the infection. The area was thoroughly irrigated using pulsed lavage with 30 liters of saline. Finally, a cement mold was inserted into the femur (Fig. ). The cement mold consisted of 120 g bone cement and 6 g of vancomycin. The patient was administered 1,200 mg of linezolid for 14 days. Streptococcus mutans, a Gram-positive coccus was identified in all four of the intraoperative specimens (Table ). The antibiotics were subsequently changed to a combination of 900 mg of clindamycin and 1000 mg of ampicillin.\nThe patient was referred to the department of dental surgery at our institution for an assessment of her dental problems. The dentist diagnosed her with caries.\nHowever, Streptococcus parasanguinis, a resident of the flora of the oral cavity was identified only in specimens obtained from the patient’s mouth. The laboratory findings related to infection were all within the normal ranges, and the patient underwent revision total hip arthroplasty eight weeks after the implant removal.\nThe operation was performed using an HA-coated cementless femoral component, an HA-coated cementless acetabular shell, a polyethylene liner and a zirconia ball (Kyocera, Kyoto, Japan).\nA morselized allogenic bone graft was packed on the floor of the acetabulum (Fig. ).\nFollowing completion of the total revision surgery, the patient continuously received oral antibiotics consisting of 900 mg of clindamycin and 1000 mg of ampicillin for six months.\nThe last follow-up occurred approximately 23 months after the total revision surgery, at which time, all laboratory findings indicative of infection remained well within the normal limits, no clinical signs of infection were noted and the prosthesis appeared to be well fixed radiographically. The patient is currently able to walk without a cane.