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Subchondral microfracture of the knee without osteonecrosis after arthroscopic medial meniscectomy

Norimasa Nakamura1, Shuji Horibe, Shigeko Nakamura

  • 1Department of Orthopaedic Sports Medicine, Osaka Rosai Hospital, Osaka, Japan. nori@orh.go.jp

Insights

A knee lesion after arthroscopic medial meniscectomy mimicked osteonecrosis but was actually a subchondral microfracture. Histologic analysis confirmed healing bone, not bone death, following the knee surgery.

Area of Science:

  • Orthopedic Surgery
  • Sports Medicine
  • Musculoskeletal Imaging

Background:

  • Arthroscopic medial meniscectomy is a common procedure for knee injuries.
  • Post-operative osteonecrosis of the knee is a rare but serious complication.
  • Clinical and imaging findings can overlap between osteonecrosis and other knee pathologies.

Observation:

  • A patient developed a knee lesion shortly after arthroscopic medial meniscectomy.
  • Clinical presentation and magnetic resonance imaging (MRI) findings were suggestive of osteonecrosis.
  • The lesion presented with pain and restricted movement, similar to reported osteonecrosis cases.

Findings:

  • Histologic examination revealed subchondral microfracture with active callus formation.
  • The lesion was definitively diagnosed as a healing bone injury, not osteonecrosis.
  • Microfracture indicates a bone stress injury rather than avascular necrosis.

Implications:

  • This case highlights the importance of histologic analysis in diagnosing post-arthroscopic knee lesions.
  • It suggests that some osteonecrosis-like presentations after meniscectomy may represent treatable bone microfractures.
  • Accurate diagnosis is crucial for appropriate management and patient outcomes in post-operative knee complications.

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