Acetabular liner with focal constraint to prevent dislocation after THA

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering

Background:

• Dislocation is a common cause of failure in total hip arthroplasty (THA).
• Fully constrained liners, while designed to prevent dislocation, have associated failure risks including redislocation and mechanical issues.
• Constrained liners with cutouts may improve range of motion and reduce dislocation risk, but their clinical impact on wear and loosening is uncertain.

Purpose of the Study:

• To determine the occurrence of dislocation with constrained liners featuring cutouts.
• To evaluate the complication rates associated with these specific constrained implants.
• To assess the incidence of early cup loosening in THA patients.

Main Methods:

• Retrospective review of 81 patients (82 THA procedures) who received constrained liners with cutouts between 2008-2010.
• Patients were at high risk for dislocation, undergoing primary or revision THA.
• Minimum follow-up of 24 months (mean 34 months) to assess outcomes.

Main Results:

• A low rate of liner failure due to dislocation was observed (3%).
• Three cases of deep infection and one instance of progressive loosening at the shell-bone interface were reported.
• No other significant mechanical failures or construct failures were noted.

Conclusions:

• Constrained liners with cutouts appear to offer a low risk of dislocation in high-risk THA patients.
• These implants may be beneficial for patients with a history of recurrent dislocation.
• Further research could explore long-term wear and loosening rates.