Synovial fluid microanalysis allows early diagnosis of ceramic hip prosthesis damage

The first clinical sign of ceramic hip prosthesis failure is hip noise. We therefore investigated whether isolation, observation at scanning electron microscopy, and chemical identification with microanalysis of particles from synovial fluid of "noisy hip" could be predictive of ceramic damage. Firstly, the level of "physiological wear" of well functioning ceramic-on-ceramic hip prostheses was assessed with this method, then the test was validated as diagnostic method for liner fracture. Twelve asymptomatic patients were enrolled to demonstrate the first aim; 39 cases of noisy hip (GROUP 1), and 7 cases of pending failure not related to ceramic (GROUP 2) were enrolled for the second aim. The analysis of the synovial fluid of the 12 asymptomatic patients allowed to set the "physiological wear" threshold. The analysis of GROUP 1 hips demonstrated the presence of ceramic particles (2 physiological, 12 mild, and 25 strong). The analysis of GROUP 2 showed a physiological presence of ceramic particles in all cases. Revision surgery in GROUP 1 was performed in 16 hips out 25 with strong ceramic particle presence and 2 out of 12 with mild ceramic particle presence. Failure of the ceramic component was evident in all but one of these cases, while the integrity of components was demonstrated in all seven hips of GROUP 2. Synovial fluid microanalysis can be a useful surrogate in predicting ceramic failure particularly when a strong presence of ceramic particles is observed. On the contrary there is not enough evidence to predict ceramic failure in presence of mild positivity.