Dissociation of liner from cup in THA: does liner damage affect the risk of dissociation?

Archives of Orthopaedic and Trauma Surgery, 2023 · DOI: 10.1007/s00402-022-04529-8 · Published: July 5, 2022

Simple Explanation

Total Hip Arthroplasty (THA) modular components allow for surgical flexibility; however, a rare failure is dissociation between the liner and cup. This study evaluates the resistance to lever-out forces of different acetabular cup and liner designs. The Pinnacle system, with intact anti-rotation tabs, demonstrated higher stability. However, the anti-rotation tabs are a critical component of the locking mechanism.

Study Duration

Not specified

Participants

20 cup/liner samples

Evidence Level

Not specified

Key Findings

1
The Pinnacle construct with intact ARTs required the greatest force to achieve dissociation, followed by Plasmafit Plus7 and Allofit-S constructs.
2
After removal of the ARTs, the Pinnacle system required the least force to achieve dissociation.
3
The ARTs of the Pinnacle system were critical to the integrity of the locking mechanism.

Research Summary

This study evaluated the resistance of different cup/liner systems to lever-out forces, a potential cause of liner dissociation in THA. The Pinnacle system with intact ARTs showed the highest stability, but removal of ARTs significantly reduced its resistance to dissociation. The study underscores the importance of ARTs in maintaining the integrity of the Pinnacle locking mechanism and highlights potential failure mechanisms.

Practical Implications

Surgical Technique

Careful attention to liner seating and optimal cup orientation during THA is crucial to prevent impingement and dissociation.

Patient Education

Patients should be educated about avoiding extremes of ROM and seeking prompt attention for hip pain or instability.

Component Selection

Surgeons should carefully consider component selection, avoiding large femoral head/thin PE rim combinations.

Study Limitations

1
Only one type of Pinnacle liner was used.
2
Our study utilized only two types of cup/liner constructs other than Pinnacle/Marathon.
3
Our study does not evaluate the effects of head size and/or liner thickness on liner dissociation.

Your Feedback

Was this summary helpful?

Back to Orthopedics