Aim

Prosthetic joint infection (PJI) is a major complication in THA. Nasal carriage with S. Aureus is a well-defined risk factor for infection in hospitalized patients. Risk for infection is reduced up to 50% by eradication therapy. Since PJI rates are very low and only 25% of the population are carriers, significant differences are hard to show and reports on PJI have been inconclusive. We analysed the effect of S. Aureus eradication therapy in THA.

Bone impaction grafting of the femur is associated with more complications when segmental defects are present. The effect of segmental defect repair on initial stem stability was studied in an in vitro study with fresh frozen goat femora. A standardized medial segmental defect was reconstructed using a cortical strut or a metal mesh. As controls we used intact femora and femora with a non-reconstructed defect. In all four groups impacted bone grafting was performed in combination with a cemented Exeter stem. Each group contained five femora. Reconstructions were dynamically loaded up to 1500N. Migration was measured with Roentgen Stereo-photogrammetric Analysis. All cases with a non-reconstructed segmental defect failed into excessive varus rotation. None of the femora with a reconstructed defect failed. Cortical struts and metal meshes were equally effective in creating a stable stem construction (varus rotation 2.89±2.27 and 2.27±0.57, respectively). Reconstructions with a metal mesh were more reproducible, although the obtained stability was significantly lower (p< 0.01) when compared to impaction grafting in an intact femur (varus rotation 0.58±0.36).

Besides, structural grafts may negatively influence the revascularization of the underlying impacted grafts in contrast to an open wire mesh. So, an in vivo study of 12 goats was done. A standardized medial wall defect was reconstructed with a strut or a mesh in six goats per group. In all femora impaction grafting was performed in combination with a cemented Exeter stem. After six weeks the femora were harvested. A high rate of peri-prosthetic fractures was found (43% and 29% for the strut and mesh groups, respectively). Histological and micro-radiological examination showed different revascularization patterns for both reconstruction techniques. In the strut group revascularized graft was found at the edges of the defect. In the mesh group fibrous tissue and blood vessels penetrated through the mesh and a superficial zone of revascularized grafts was found. Segmental defect reconstruction with a strut reduced the amount of revascularized grafts medially behind the strut (p=0.004). This may interfere with the stability of the stem in the first period after surgery and the incorporation of the impacted grafts on the long-term.

We would recommend segmental defect reconstruction with a mesh. A regime of unloading and long-stem prostheses should be used, irrespective of the reconstruction technique

Aims: To test the outcome of acetabular revisons with impacted morsellized bone grafts and a cemented cup at a minimum follow-up of 15 years. Methods: Between 1979–1986 62 acetabular revisions (58 patients) were performed with impacted bone grafts and a cemented cup. Two cases (2 hips) were lost to FU. The average age at operation was 59.1 years. The indication was aseptic in 56 and septic loosening in 4 hips. Defects were AAOS-classiþed as ñcavitaryñ in 37 and ñcombinedñ 23 cases. Femoral-head allografts were used. Acetabular re-revisions were determined, the HHS obtained and radiographs analyzed. Results: Nineteen cases (20 hips) died within þfteen years after the operation, none had a re-revision. Eleven acetabular re-revisions were performed: 2 septic loosenings (3 and 6 years p.o.), 7 aseptic loosenings (6, 9, 11, 12, 13, 14, 14 year p.o.) and two for cup wear (12 and 17 yrs p.o.). The average HHS at follow-up was 86 (50–100). There were no additional radiographic failures. Using Kaplan-Meier analysis the survival with endpoint revision for any reason was 79% at 15 years and 71% at 20 years; for aseptic loosening of the cup 84% at 15 years and 84% at 20 years. Conclusions: This technique is attractive to reconstruct acetabular bone stock loss.