【双语病例】软骨下机能不全性骨折

History

A 55-year-old woman presents with medial, left knee pain that has progressed over the past few months. She has no history of trauma.

55岁女性，左膝内侧疼痛，加重数月余。无外伤史。

Findings and Diagnosis

Findings

Radiographs: Frontal radiograph demonstrates a subtle area of subarticular sclerosis with adjacent lucencies along the medial femoral condyle. There is no evidence of articular collapse. Alignment is maintained. There is no joint effusion on lateral view.膝关节正位片示股骨内侧髁软骨下可见轻微的骨质硬化，周围可见透光区。无关节塌陷，关节对位良好。侧位片示无明显关节积液。
MRI: There is a curvilinear low signal in the subchondral medullary bone of the medial femoral condyle on T1- and T2-weighted sequences, corresponding to region of abnormality seen on radiographs. There is T2-hyperintense signal in the adjacent marrow, reflecting edema. There area areas of focal irregularity and partial thickness loss of the corresponding medial femoral articular cartilage but no areas of full-thickness cartilage loss. There is no medial meniscal tear. The medial collateral ligament is intact, but there is a small amount of fluid medial to the ligament, reflecting sequelae of grade I sprain.股骨内侧髁于T1WI、T2WI可见软骨下线状低信号影，临近骨髓水肿，呈长T2信号。对应的股骨内侧关节面软骨边缘不规则，局限性变薄，但无软骨消失。内侧半月板无明显撕裂。内侧副韧带完整，但韧带内侧见少量积液，考虑为I度损伤后遗症。

Differential Diagnosis

DiagnosisSubchondral insufficiency fracture软骨下机能不全性骨折

Key Points

Pathophysiology 病理生理学

Nomenclature: Spontaneous osteonecrosis of the knee (SONK) was previously used synonymously, but term is considered misnomer given underlying etiopathogenesis corresponds to insufficiency fracture.命名：既往曾称为膝关节自发性骨坏死，但这一命名不能反映技能不全性骨折的发病机理。
Mildly impacted fracture along the subchondral medullary bone, with histology of affected regions often demonstrating hemorrhage and edema.软骨下髓质骨受到轻微的撞击伤，常表现为局部的出血和水肿。
Fracture occurs as result of repetitive stress on areas of weakened bone (i.e., in the setting of osteopenia or osteomalacia).骨质薄弱的区域（如骨质疏松、骨质软化）反复损伤最终引起骨折。
- Typically occurs in large weight-bearing joints.通常发生在负重的大关节。
- In the knees, can affect femoral or tibial weight-bearing articular surfaces.在膝关节，可累及股骨或胫骨的负重关节面。

Associated injuries include medial meniscal tears.可合并内侧半月板损伤。
Natural history: Patients with subchondral insufficiency fractures have an increased risk of developing secondary osteonecrosis, subchondral collapse, and/or secondary osteoarthritis.软骨下机能不全性骨折的患者，发生继发骨坏死、软骨下塌陷、继发性骨关节炎的几率增加。

Epidemiology 流行病学

Middle-aged to elderly patients中老年人
Female gender predilection好发于女性
Higher frequency in Asian and Caucasian patients as opposed to African-Americans亚洲和高加索人群发病率高于非洲、美洲。

Clinical Presentation 临床表现Patients present with progressive pain and/or swelling in the absence of trauma.患者通常无外伤史，表现为渐进性疼痛、伴有或不伴有关节肿胀。

Radiograph imaging

Demonstrate normal or diffuse osteopenia without acute findings in many cases.X线通常表现为正常，或弥漫性骨量减少，而没有急性改变。
Findings include the following:X线表现包括：

Subchondral lucency 软骨下透光区
Subchondral sclerosis (reflects impaction and/or healing) 软骨下骨质硬化（通常反映撞击及撞击后的恢复）

MR imaging

Fracture plane in subchondral medullary bone along the articular surface of the femoral condyles, with serpiginous low signal band on all sequences.骨质线沿股骨髁关节面走行于软骨下髓质骨内，所有序列均表现为匐行低信号。
Adjacent marrow edema in the acute/subacute phase on fluid-sensitive sequences.液体敏感序列可见急性/亚急性期骨质水肿。
Cartilage should not be damaged, but assessment can be confounded by pre-existing degenerative/post-traumatic changes.关节软骨通常无破坏，但如果之前存在退变或外伤后改变，可能会使评估产生一定的困难。
Associated findings:合并症：