Dissociation of Acetabular Polyethylene Liners With a Morse Taper Design.

Background: Polyethylene liner dissociation is an uncommon complication of hip replacement. Dissociation has been associated with particular acetabular component designs. This study reviewed acetabular liner dissociations in a specific modular cup with a Morse taper locking mechanism that has not been previously reported.

Methods: The senior author performed 655 primary total hip arthroplasties with one particular design of acetabular component using Class A polyethylene liners and metal head articulation. Cases with revision surgery performed for acetabular liner dissociation were reviewed.

Results: Seven of 655 patients with this cup underwent revision surgery for a dissociated liner. Liner dissociation occurred at a mean of 73 months postoperatively. Patients presented with new-onset hip pain or squeaking, 4 of which developed symptoms acutely. Two patients treated with polyethylene liner exchange into the same cup required a second revision surgery for recurrent dissociation.

Conclusion: Polyethylene liner dissociation is an infrequent but possible complication associated with modular acetabular components using a Morse taper locking. Providers should be vigilant with long-term follow-up of patients with this acetabular system for patient complaints of catching or squeaking. Patients treated for liner dissociation should not have a new liner placed into the same acetabular shell given the risk for further dissociation.