Subchondral insufficiency fracture of the knee: a non-traumatic injury with prolonged recovery time

Abstract

Subchondral insufficiency fractures are non-traumatic fractures that occur immediately below the cartilage of a joint. Although low bone density may be present concurrently, it is not the underlying cause of subchondral insufficiency fractures in the majority of patients. Patients with subchondral insufficiency fracture characteristically have unremarkable plain radiographs, while MRI examination may reveal extensive bone marrow oedema and subchondral bone collapse. This article presents a 51-year-old postmenopausal woman, a physician, who had subchondral insufficiency fractures of the knee associated with prolonged standing during clinical work. She was treated with partial weight bearing on crutches until 14 months after the injury, viscosupplementation at 4 months to treat osteoarthritis and teriparatide treatment to improve bone healing at 7 months. By 26 months after the injury, she tolerated independent walking with a fabric knee support but still experienced mild posterolateral knee pain and numbness on prolonged standing.

Figure 1

Coronal (A) and sagittal (B) T2-weighted, fat-suppressed MRI of the right knee 58 days after injury. There is diffuse marrow oedema throughout the lateral femoral condyle and a minimal lateral femoral condylar depression (arrow) consistent with a subchondral insufficiency fracture.

Figure 2

Anteroposterior radiograph of both knees (A) and a lateral radiograph of the right knee (B) show minimal osteophytosis, but are otherwise normal.