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Atraumatic osteonecrosis of the patella
K M Baumgarten1, M A Mont, A Rifai
1Johns Hopkins University School of Medicine, Department of Orthopaedic Surgery, The Good Samaritan Hospital, Baltimore, MD, USA.
Clinical Orthopaedics and Related Research
|February 24, 2001
Summary
Atraumatic secondary osteonecrosis of the patella, a rare condition, typically affects patients with high corticosteroid exposure or systemic lupus erythematosus. This nonprogressive disease, often localized to the superior patella, rarely requires surgical intervention.
Area of Science:
- Orthopedics
- Radiology
- Rheumatology
Background:
- Atraumatic secondary osteonecrosis of the patella is an uncommon condition.
- Previous reports are limited to a few case studies.
Purpose of the Study:
- To characterize the clinical and radiographic features of patellar osteonecrosis.
- To determine the outcome of this rare condition.
Main Methods:
- Retrospective review of 25 knees in 19 patients diagnosed with patellar osteonecrosis.
- Analysis of patient demographics, medical history, imaging findings (MRI, plain radiographs), and clinical outcomes.
- Mean follow-up of 4 years.
Main Results:
- The mean patient age was 42 years.
- Common risk factors included high lifetime corticosteroid exposure (95%) and systemic lupus erythematosus (32%).
- Osteonecrosis was consistently found in the superior patella on MRI (100%). Plain radiographs detected lesions in 20% of knees, with only one case showing posterior surface collapse.
- No surgical intervention was required for the patellar lesions during follow-up.
Conclusions:
- Patellar osteonecrosis is associated with concurrent distal femur and proximal tibia lesions.
- The disease typically presents with osteonecrosis localized to the superior pole of the patella.
- It is a nonprogressive condition that generally does not necessitate surgical treatment.