Knee extensor mechanics after subtotal excision of the patella

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Musculoskeletal Research

Background:

• The patella is crucial for efficient knee extension by improving the lever arm of the quadriceps femoris muscle.
• Understanding the impact of patellar resection on quadriceps function is vital for optimizing surgical outcomes.

Purpose of the Study:

• To determine the quadriceps force requirements for knee extension following different degrees of patellar excision.
• To compare the biomechanical effects of sequential distal-to-proximal and proximal-to-distal patellar excisions with total patellectomy.

Main Methods:

• Utilized fresh frozen autopsy specimens (n=12) for biomechanical testing.
• Measured quadriceps force during knee extension at various flexion angles after incremental patellar fragment removal.
• Compared force data against baseline and total patellectomy conditions.

Main Results:

• Excision of 50% or less of the proximal patella resulted in decreased quadriceps force demands compared to total patellectomy.
• Removal of the proximal three-fourths of the patella showed inconsistent effects, sometimes increasing force requirements.
• Distal-to-proximal excisions suggested a biomechanical benefit when retaining at least 75% of the proximal patellar length.

Conclusions:

• Retaining a significant portion of the patella, specifically at least three-fourths of its proximal length, is biomechanically advantageous.
• Partial patellar preservation can mitigate the increase in quadriceps force demand associated with patellectomy.
• Maintaining adequate patellar fragment size helps preserve the mechanical efficiency of the extensor mechanism.