MobileLink Acetabular Cup System with Face Changer: Dislocation-stable revision of a septically loosened acetabulum

Case Report: directLINK 2/2022
 

In February 2021, a 72-year-old female patient, who had been fitted with hip arthroplasties on both sides since 2005, presented to the Hip Department of the Waldkliniken Eisenberg, Germany. The patient‘s medical history revealed increasing pain in the right hip joint, which had been limiting mobility for about two years. X-rays showed a loosening of the in situ screw cup on the right with migration of approximately 20 mm cranially and tilting to 85 degrees inclination as well as a destruction of the acetabular bearing dorsally by the screw cup. Microbiology of a puncture specimen from the hip joint revealed Staphylococcus epidermidis and confirmed the diagnosis of periprosthetic infection and septic loosened acetabulum.

After complete removal of the right hip arthroplasty, surgical debridement and lavage in March 2021, a Girdlestone situation with spacer was created, according to
in-house regimen in a two-stage procedure. The defect of the acetabulum was classified as Paprosky IIb. 

Reimplantation of the hip arthroplasty with allogeneic spongiosaplasty to fill the defect cranially, performed in May 2021, confirmed a posterior acetabular wall destroyed dorsally by the screw cup. Because of possible impairment of the primary stability of the cup and to allow a press-fit, reimplantation was performed with 10-15 degrees of retroversion. A 20-degree Face Changer was implanted to set an anteversion to avoid an increased tendency to dislocation, resulting in an antetorsion of approximately 5-10 degrees. In addition, the revision cup was stabilized using two screws. The following components of the MobileLink Acetabular Cup System from LINK were used: 

• MobileLink TiCaP Cluster Hole Size 62 
• Face Changer 8 mm offset, 20° inclination
• Insert PE, Size E 
• Screws 6.5/20 mm und 6.5/35mm

Postoperatively, the patient was partially loaded with 20 kg and gradually fully loaded after 6 weeks. The modular MobileLink Acetabular Cup System had made it possible to position the acetabulum securely and with stable luxation. Because the posterior acetabular rim was missing, implantation of the primary cup in slight retroversion was necessary to ensure stable anchorage of the cup. Thanks to the Face Changer, it was possible to set the inclination and anteversion within the anticipated »safe zone« according to Lewinnek. The result is reflected in the pain-free and safe mobilization of the patient. A control X-ray after 12 weeks showed a secure acetabular fit without secondary dislocation and clinically stable joint conditions.