OBJECTIVETo study the efficiency of decreasing instability of large femoral head components in revision total hip arthroplasty (THA).

METHODSFrom August 2005 to December 2010, 107 patients (112 hips) with 28 mm femoral head components (28 mm group) and 46 patients (46 hips) with 36 mm femoral head components (36 mm group) in revision THA were analyzed retrospectively in order to find if the dislocation rate and Harris hip score were different between the two groups at the time of last follow-up. All the operations were performed by the first author. There were 81 male patients (85 hips) and 26 female patients (27 hips) in 28 mm group with mean age of (62±17) years (26-79 years) and 33 male patients (33 hips) and 13 female patients (13 hips) in 36 mm group with mean age of (60±16) years (31-77 years).

RESULTSThe mean follow-up period was 43.3 months (33-71 months) for 28 mm group and 26.7 months (12-37 months) for 36 mm group. There were 7 patients dislocated after revision in 28 mm group, including 2 revised with reinforcement rings (with dislocation rate 9.5%), 3 revised with impaction bone grafting technique (with dislocation rate 8.3%) and 2 revised with cementless cups (with a dislocation rate 3.6%). The dislocation rate of this group was 6.2%. While the dislocation rate of 36 mm group was 2.2%, the only dislocated patient was because of loss of gluteus medius muscle function in the index operation. If this case was excluded, the dislocation rate of 36 mm group would be 0. There was significant difference between the two groups (χ2=103.0095, P<0.01). The Harris hip score was 88±11 for 28 mm group and 89±9 for 36 mm group, there was no significant difference between the two groups (P>0.05).

CONCLUSIONThe large femoral head components can significantly decrease the instability after revision THA, which should be used in revision THA.