Painful knee prosthesis: surgical approach.

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Diagnostic Imaging

Background:

• Painful knee prostheses present a diagnostic challenge, with common causes including infection, aseptic loosening, instability, and arthropathy.
• Prosthetic infection requires prompt diagnosis and often a two-step revision, while aseptic loosening necessitates implant revision for stability.
• Instability and patellofemoral issues can stem from technical errors or component malalignment, requiring specialized implants or revision procedures.

Purpose of the Study:

• To review the diverse etiologies of painful knee prostheses.
• To outline diagnostic approaches for common and less common causes of prosthetic failure.
• To discuss treatment strategies, including revision surgery and management of metal sensitivity.

Main Methods:

• Review of literature on painful knee prosthesis diagnosis and management.
• Analysis of common failure modes: infection, aseptic loosening, instability, patellofemoral issues.
• Consideration of less common causes like referred pain, neuromas, and metal sensitization.

Main Results:

• Prosthetic infection is a primary consideration, managed with two-step revision.
• Aseptic loosening and instability often require implant revision, with implant choice depending on the type of instability.
• Patellofemoral pain may necessitate component evaluation, resurfacing, or revision due to tracking issues or malalignment.
• Unexplained pain may involve referred pain, ligament/tendon issues, neuromas, or metal sensitization, particularly to nickel.

Conclusions:

• Effective management of painful knee prostheses relies on accurate diagnosis of diverse causes, ranging from mechanical failures to biological responses.
• Prompt identification and treatment of prosthetic infection are critical.
• Metal sensitization, especially to nickel, is an underappreciated cause requiring minimal nickel content in revision implants.