Patella resurfacing in total knee replacement: functional evaluation and complications.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering

Background:

• Patellar complications and function are critical in total knee arthroplasty (TKA).
• Trochlear design variations can influence patellofemoral mechanics and outcomes.

Purpose of the Study:

• To prospectively evaluate three different knee replacement trochlear designs for clinical and radiographic patellar function.
• To assess the incidence of patellar complications associated with each design.

Main Methods:

• Clinical and radiographic evaluation of three knee replacement designs: Insall-Burstein I (IB-I), Insall-Burstein II (IB-II), and Meniscal Bearing Knee (MBK).
• All patients received an all-polyethylene dome patellar prosthesis.
• Exclusion of knees with pre-existing tibiofemoral issues.

Main Results:

• Early IB-I design had high impingement rates ('clunks'), reduced to 5% after smoothing the anterior edge.
• IB-II design showed improved degree of clunks (4.5%) due to deeper trochlea for soft tissue clearance.
• MBK design demonstrated very rare clunks and improved patellar function.
• Patellar stress fractures and instability were infrequent across all designs; loosening or wear was not evident.
• Over 80% of patients achieved normal function (including stairs).
• Patella baja was the only radiological parameter correlated with symptoms in IB prostheses.

Conclusions:

• Trochlear design significantly impacts patellofemoral mechanics and patient outcomes in knee arthroplasty.
• The Meniscal Bearing Knee (MBK) design offers superior patellar function and reduced impingement.
• Dome patellar prostheses are preferred for their tolerance and potential for conforming to the trochlear groove.