Effects of Internal Fluid Pressure on Stresses in Subchondral Bone Cysts of the Medial Femoral Condyle

Triangular Margin: Reliable Imaging Feature of Fibrous Dysplasia in Long Bones?

OBJECTIVE

To determine the utility of a triangular margin as an imaging diagnostic feature for fibrous dysplasia.

MATERIALS AND METHODS

We retrospectively reviewed all surgically biopsied or managed benign and malignant bone tumors by a single orthopedic oncologist over 19 years (2003 to 2022). A musculoskeletal radiologist and an orthopedic oncologist, both with >10 years of experience, retrospectively evaluated all imaging in consensus. Groups were compared using the χ2 test.

RESULTS

There were a total of 152 subjects [mean age 49±21 (range 7.8 to 91) years]; 80 (53%) females and 72 (47%) males. There were 52 subjects with fibrous dysplasia, 31 subjects with other benign bone tumors, and 69 subjects with malignant bone tumors. The sensitivity and specificity of a triangular margin for distinguishing fibrous dysplasia from other benign or malignant bone tumors were 74% and 96% on radiographs, 73% and 100% on CT, and 78% and 91% on MRI, respectively. The triangular margin was more prevalent in fibrous dysplasia (85%) versus benign (16%) and malignant (1.6%) primary bone tumors in all 3 modalities (P<0.001). Multivariate analysis of the aggregated imaging data suggests that if a lesion has a triangular margin, it is 14 times more likely to be a fibrous dysplasia than another benign bone tumor (P=0.012).

CONCLUSIONS

The presence of a triangular margin could increase a radiologist's confidence that a bone tumor is fibrous dysplasia.

Equine subchondral lucencies: Knowledge from the medial femoral condyle

Equine subchondral lucencies (SCL) have been described since the first availability of suitable radiographic equipment. The initial clinical sign can be lameness, but SCLs are often first found on surveys of juvenile horses and are primarily a radiographic concern for public auctions. When lameness is present, it varies from subtle to obvious and can be intermittent. Some SCLs heal spontaneously, and some remain blemishes, but when the SCL and lameness are persistent, further damage to the joint and limitations to an athletic career are likely. SCLs were initially described in the distal limb followed by the stifle, and the medial femoral condyle (MFC) is now considered the most common location. The aim of this review is to highlight the initial pathology and discuss the clinical and experimental information available on equine SCLs. SCL treatment has evolved from rest alone and has progressed to debridement, grafting, intralesional injection, and most recently, transcondylar screw and absorbable implant placement. Comparison of success rates between techniques is difficult due to variations in follow-up and outcome measures, and no single technique is best for all SCLs. Treatment appears to increase success by 15%-20% over rest alone, but the method chosen depends on many factors. This review emphasizes the need for further work to fully understand SCL formation and all aspects of trabecular bone healing to optimize surgical therapy and improve treatment success.