Abstract
We prospectively analyzed 83 patients who underwent ceramic-on-ceramic THA using preassembled (n = 22) or modular acetabular components (n = 61) between June 2010 and June 2012. No radiographic evidence of progressive radiolucency, osteolytic lesions, acetabular fractures, or component migration was detected in either group. Furthermore, no patient required revision surgery for instability or ceramic breakage. Table 1 shows the mean postoperative HHS, WOMAC score, and acetabular component inclination and anteversion in groups A and B. No significant differences in mean postoperative HHS (P < 0.056), WOMAC score (P < 0.258), acetabular component inclination (P < 0.827), or anteversion (P < 0.549) were observed between the two groups according to the independent sample t-test. However, the chi-square (Fisher's exact) test showed a significant difference between the two groups with respect to the gender of the patients (P < 0.001, Table 2). These findings indicate that half of the women had smaller acetabular diameters accommodating a cup size of only 48–50-mm. Thus a preassembled ceramic liner is a very good option for women with a small acetabulum, which could permit the use of a larger femoral head (36-mm) with thin-walled acetabular components. In contrast, the component-specific complications between the two groups were quite similar. One patient (group B) had transient squeaking that disappeared after a few months. One patient (group B) had a mild limp caused by abductor muscle weakness, and one patient (group B) had a superficial wound infection that was treated with local debridement and antibiotics. Early dislocation (P < 0.488) occurred in three patients (one in group A and two in group B). Two patients (one in group A and one in group B) reported postoperative falling events at their bedside. The other in group B was a female with rheumatoid arthritis, which can lead to a much higher risk of dislocation due to soft tissue laxity around the hip joint. All of these patients were treated by closed reduction without further incident. Three patients (one in group A and two in group B) had mild iliopsoas pain (P < 0.488) that was not associated with loosening; however, the pain did not limit their activities (Table 3). In conclusion, we found no significant differences in the mean postoperative radiographic or functional outcomes or complications between the two groups, showing satisfactory performance at the 2 year follow up. Only the gender of the patient was significantly different between the two goups, demonstrating that a larger number of women had smaller acetabular diameters accommodating a cup size of only 48–50-mm. Although a preassembled cup with a 36-mm ceramic liner has proven safety in the short term, future research should focus on its long-term risks.
