Patellar bone stock after extra-articular knee resection preserving extensor mechanism: A cadaveric study

Area of Science:

• Orthopedic Surgery
• Anatomy
• Radiology

Background:

• Extra-articular knee resection (EKR) preserving the extensor mechanism is a surgical technique used in knee procedures.
• Evaluating the remaining patellar bone stock after EKR is critical for surgical planning and preventing complications.

Purpose of the Study:

• To assess the thickness of the remaining patellar bone after extra-articular knee resection (EKR) while preserving the extensor mechanism.
• To compare macroscopic measurements from cadaveric knees with magnetic resonance imaging (MRI) findings.

Main Methods:

• 14 human cadaveric knee joints were dissected to measure patellar thickness.
• Axial MRI scans of 100 adult and 25 pediatric knees were analyzed for patellar thickness.
• Statistical comparison was performed between cadaveric and adult MRI measurements.

Main Results:

• The mean residual patellar bone thickness in cadavers was 8.2 mm, with 71.4% having less than 10 mm.
• In MRI scans, average residual patellar thickness was 8.6 mm in adults and 6.9 mm in pediatric knees.
• 72% of all MRI scans showed residual patellar thickness less than 10 mm.

Conclusions:

• The remaining patellar bone stock after EKR preserving the extensor mechanism is often insufficient.
• Preoperative MRI assessment is recommended to guide surgical technique selection and avoid complications related to patellar resection.