[Surgical therapy of osteolysis around stable cementless hip arthroplasty].

Purpose Of The Study: The article presents results of surgical treatment of osteolysis around stable cementless THA.

Material And Methods: The authors evaluated 18 operated on cases of osteolysis around stable THA of ABG 1 type with a minimal follow-up of 4 years (49-70 months). The group included 6 men and 12 women who were at the time of revision 47 years old (36-56, SD 6.52). The average period between the primary and revision surgery was 45 months (23-66, SD 13.84), the average size of the original cup was 49.6 mm (44-54, SD 3.03), the median thickness of polyethylene was 7.5 mm (4.9-8.9). The average HHS prior to reoperation was 68.5 points (10-98, SD 18.3) and only three hips were completely asymptomatic (3/18, 17%). Polyethylene inlay was replaced twice, both acetabular components in twelve cases, the acetabular and femoral components in four cases. In 16 cases radical debridement and treatment of defects by bone grafting was an important part of surgery.

Outcomes: By the time of the latest check, in total three revision surgeries were performed (3/18, 17%). Neither of them was necessitated by loosening of the revision cup or use of bone grafts. Revised were both hips after the replacement of polyethylene cup inlay. Stable bone fixation and healing of bone defect was achieved in 15 hips in which the implant replacement was combined with bone grafting (15/16, 94%). The revision cup was on average by 3.16 mm bigger than the original cup (p = 0.001). The average HHS during the latest check was 79 points (p = 0.056).

Discussion: In osteolysis around a stable implant, many North-American authors prefer the replacement of polyethylene cup inlay in case of an undamaged well-oriented metal cup with a functional lock. By contrast, the authors of this study in such indication replace the whole acetabular component. This discrepancy may be explained by the ABG 1 THA which often triggers an extensive osteolysis and fails relatively soon.

Conclusion: Despite a small number of cases the study has proved that the bone bed damaged by osteolysis is able to accommodate a new cementless implant. A necessary part of the surgery is radical debridement and in more extensive defects also bone grafting.