Unacceptable failure of the PI2® implant

Area of Science:

• Orthopedic surgery
• Biomaterials science

Background:

• Trapeziometacarpal (TM) osteoarthritis is a common condition affecting the thumb base.
• The PI2® spacer was developed as a treatment option for TM osteoarthritis.
• Concerns exist regarding the stability of the PI2® spacer due to its design.

Purpose of the Study:

• To retrospectively evaluate the clinical outcomes and revision rates of the PI2® spacer in patients with TM osteoarthritis.
• To correlate implant position and scaphometacarpal distance with clinical outcomes.

Main Methods:

• Retrospective case-series study of 45 PI2® spacers in 41 patients with TM osteoarthritis.
• Patients underwent trapeziectomy and PI2® spacer insertion between 2004 and 2009.
• Outcome parameters included revision rates, clinical outcomes, implant position, and scaphometacarpal distance assessed via radiographs.

Main Results:

• A total of 12 implants (27%) were removed, with common reasons including dislocations (5) and persistent pain (6).
• Of the 33 implants remaining, only 21 were available for clinical evaluation at a median follow-up of 29 months.
• No significant differences in clinical outcomes were found between in-place and subluxated implants.

Conclusions:

• The PI2® spacer demonstrated a high revision rate, consistent with existing literature.
• Due to high revision rates and instability concerns, the use of the PI2® spacer has been discontinued.
• A registry for evaluating future implants is recommended to improve patient outcomes.