Implant failure was detected in all patients who had been treated with the Duraloc Constrained Inlay because of recurrent dislocation (Table). Either revision surgery with an exchange of the cup implant had already been carried out (3 patients), or the expanding ring was dislocated (5 patients).
1 patient (case no. 2) underwent revision surgery due to failure of the antiluxation inlay 3 years after implantation. At revision surgery, the same type of inlay was used again. After 1 more year and another event of dislocation, this inlay was replaced with a Ganz cup and a Mueller antiluxation inlay. He used a brace for 6 weeks after surgery and no further dislocations had occurred a the latest follow-up 2 years after the intervention ().
Case no. 2: implant failure and dislocation of the second Duraloc Constrained Inlay.
1 patient (case no. 4), after change to the Durolac Constrained Inlay 7 years after primary hip arthroplasty, had to undergo another revision surgery after 10 months due to a periprosthetic fracture in the area of the major trochanter. Surgery revealed an intense metallosis resulting from contact of the dislocated expanding ring with the neck of the stem. Signs of rubbing and also polished spots on the titanium body of the neck were detected ( and ).
Case no. 4: intraoperatively, with defects at the neck of the stem.
1 patient (case no. 6) had revision surgery due to stem loosening. The expanding ring was dislocated. The cup was revised too, changing the system to a Mueller antiluxation inlay. Shortly after this intervention, another dislocation occurred.
In 4 patients (cases no. 1, 3, 5, and 7) the follow-up examination revealed a luxation of the expanding ring. These patients reported no further dislocations and had no pain. However, they had limited mobility, which they regarded as an acceptable restriction to their quality of life considering that they had remained free of dislocations.
1 patient did not consent to a follow-up examination. At a phone interview, he expressed his dissatisfaction with the outcome because of subluxation symptoms and restrictions to movement. He did not mention any inpatient treatment or dislocations.
Radiographs from any of the cases did not reveal any signs of loosening of the Durolac cups or migration of the inlays regarding their fixation in the cup.