CRP (C Reactive Protein) level after total knee replacement in Indian population--- does it follow Anglo-Saxon trend?

BACKGROUND: This study was to determine how C-reactive protein (CRP) responds after total knee replacement (TKR), including both unilateral and simultaneous bilateral TKR in Indian population and if it follows Anglo-Saxon trend. Published literature from North America and Europe shows CRP value peaks on the 2nd post-operative day and drops to normal by 6–8 weeks. We started the study with null hypothesis. MATERIAL AND METHODS: This is a prospective study, with 50 patients (all females, 25 received unilateral operations and 25 bilateral ones) included. CRP levels were measured, on the 2nd day, 8, 12 and 16 weeks after operation. RESULTS: In both groups, CRP level rose the 2nd post-operative day. The rise in CRP level was significantly higher in the simultaneous bilateral TKR group than in the unilateral TKR group. In unilateral cases, CRP on the 2nd postoperative day ranged from 65 to 110 mg/l with average level of 80 mg/ml. In bilateral TKR cases, CRP level on the 2nd postoperative day was between 110 and 180 mg/l with a mean of 140 mg/ml. The CRP level returned to normal in about 40% of unilateral TKR patients 8 weeks after operation, while in 92% (23 out of 25) of bilateral simultaneous TKR patients it stayed at a high level 8 weeks post-op and did not come back to normal. At 12 weeks CRP decreased to normal in all 100% of unilateral TKR patients and 32% of bilateral TKR patients. At 16 weeks, CRP was normal in all bilateral TKR patients. CONCLUSION: 60% of our unilateral TKR patients and 92% of our simultaneous bilateral TKR patients did not achieve a normal CRP 8 weeks after operation. These findings are significant as CRP is commonly used as a very sensitive indicator of postoperative joint infection. Hence we conclude that in the Indian TKR patients the CRP values take longer time to return to normal than in their Anglo-Saxon counterparts. Published results regarding the normal levels of CRP in unilateral TKR should not be extrapolated to simultaneous bilateral TKR patients.