Chronic periprosthetic hip infection: micro-organisms responsible for infection and re-infection.

PURPOSE: This study aimed to delineate the infecting micro-organisms identified at the first-time revision for infected THA, analyze pre-operative versus intra-operative findings, as well as intra-operative ones against re-infection micro-organisms. MATERIAL AND METHODS: Microbiological laboratory findings were studied in 73 patients (mean age, 51.93 ± 10.9 years) with chronic periprosthetic hip infection pre-operatively and intra-operatively. Forty-three patients had a two-stage revision THA while 30 patients were treated with a modified resection arthroplasty using the Ilizarov apparatus. Re-infection developed in 29 cases. Its microbial species were identified. RESULTS: Pre-operative findings on micro-organisms coincided 50.7 % with the intra-operative ones. Bacterial growth in the intra-operative tests was detected in 72 (98.5 %) cases. Gram-positive single genus infection was identified in 35 patients (48 %); microbe associations were present in 33 patients (45 %). Staphylococcus species prevailed. Gram-negative infection was detected in 5.5 % of cases. One case (1.5 %) did not have any microbe growth. Re-infection happened in 10 cases (23.2 %) in a two-stage revision THA. In the resection arthroplasty group, early re-infection was observed in 63.3 % of cases. Among a total of 29 re-infection cases, staphylococcus species were identified in 19 cases, present either in associations or as single germs. CONCLUSION: Intra-operative microbiological tests at the first-time revision for infected THR detect a reliable spectrum of micro-organisms to assess microbial resistance to antibiotics, develop treatment protocols, and for prognostic purposes. Preventive measures at primary THR and strategies to fight periprosthetic infection and reinfection should be targeted on staphylococci.

Modified Girdlestone arthroplasty and hip arthrodesis using the Ilizarov external fixator as a salvage method in the management of severely infected total hip replacement.

BACKGROUND: Resection arthroplasty or hip arthrodesis after total hip replacement (THR) can be used to salvage the limb in case with deep infection and severe bone loss. The Ilizarov fixator provides stability, axial correction, weight-bearing and good fusion rates. MATERIALS AND METHODS: We retrospectively assessed the outcomes of 37 patients with severe periprosthetic infection after THR treated between 1999 and 2011. The treatment included implant removal, debridement and a modified Girdestone arthroplasty (29 cases) or hip arthrodesis (seven cases) using the Ilizarov fixator. The Ilizarov fixation continued from 45 to 50 days in the modified arthroplasty group and 90 days in the arthrodesis group. One case was treated using the conventional resection arthroplasty bilaterally. RESULTS: Eighteen months after treatment, infection control was seen in 97.3% cases. Six hips were fused as one patient died in this group. Limb length discrepancy (LLD) averaged 5.5 cm. The Harris hip score ranged from 35 to 92 points. Hip joint motion ranged from 10° to 30° in the modified arthroplasty group. All subjects could walk independently or using support aids. No subluxation or LLD progression was observed. CONCLUSION: The modified Girdlestone arthroplasty and hip arthrodesis using the Ilizarov apparatus results in sufficient ability for ambulation and good infection control in cases of failed THR associated with severe infection.