[Patellar bone deficiency in revision total knee arthroplasty]

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Arthroplasty research

Background:

• Patellar bone deficiency significantly impacts surgical decisions in revision total knee arthroplasty (TKA).
• Various reconstructive and ablative techniques are available, tailored to the remaining bone stock.
• Understanding bone stock is critical for selecting the appropriate surgical approach.

Purpose of the Study:

• To outline surgical procedures for patellar bone deficiency in revision TKA.
• To emphasize the importance of patellar reconstruction for extensor mechanism function.
• To guide the selection of techniques based on bone availability and defect extent.

Main Methods:

• Classification of surgical options based on remaining patellar bone thickness (≥10 mm, 6-9 mm, <6 mm).
• Description of techniques including "onlay-type" and "inlay-type" patella implants.
• Inclusion of augmenting procedures like bone grafting, "trabecular metal" prostheses, and "gull-wing" osteotomy for severe bone loss.

Main Results:

• Patellar implants can be retained in up to 50% of revision cases.
• Specific reconstructive techniques are recommended based on bone thickness: "onlay" for ≥10 mm, "inlay" for 6-9 mm with intact rim.
• For deficient bone stock (<6 mm) or absent rim, bone grafting, "trabecular metal" prostheses, or "gull-wing" osteotomy are indicated.

Conclusions:

• Patellar reconstruction should be the primary goal in revision TKA due to its biomechanical importance.
• Restoring stable fixation and proper patellar tracking is essential for functional outcomes.
• Avoidance of patelloplasty or patellectomy is recommended whenever possible.