Late-Stage Perthes Sequelae in Adulthood: A Case Study CaseNo: MSK.4.6.3.3.2.001

Chief Complaint: 67 -year-old male, Left hip pain persisting for 20 years, becoming progressive over the last 2 years, accompanied by a significant limp.

​History: A history of untreated/undiagnosed hip disorder during childhood (consistent with late-stage Perthes sequelae).

​Physical Examination: 2 cm shortening of the left lower extremity, positive Trendelenburg sign, and severe restriction in the range of motion (ROM) in all directions.

Radiological Findings: 

Fig 1: Coxa Plana: Marked flattening and loss of sphericity of the femoral head.

Lateral Extrusion: Lateral displacement of the femoral head beyond the acetabular

Joint Space Narrowing: Asymmetric loss of joint space and incongruity.

Subchondral Sclerosis: Increased bone density at the acetabular roof.

​Degenerative Cystic Changes: Secondary

​ osteoarthritic subchondral cysts.

Fig 2 : Coxa Magna: Shortened and widened femoral neck.

Fig 3 : Rope Sign: Pathognomonic transverse sclerotic line at the head-neck junction.

Radiological Findings of Legg-Calvé-Perthes Disease

​1. Femoral Head and Joint Space

​Femoral Head Morphology: Significant flattening of the femoral head (coxa plana), fragmentation, and lateral enlargement (extrusion/asphericity) are observed.

​Joint Space: Asymmetric narrowing of the left hip joint space is present, indicating a loss of congruity with the acetabular roof and the onset of secondary degenerative changes.

​Acetabular Changes: An increase in acetabular roof sclerosis and secondary degenerative hypertrophy (incongruity) due to the enlargement of the femoral head are noted.

​2. Femoral Neck and Metaphysis

​Femoral Neck: Shortening and widening of the femoral neck (coxa magna) are observed. The high-riding greater trochanter (proximal migration) correlates with limb length discrepancy.

​3. "Rope Sign" - Critical Detail

​This finding is pathognomonic in Perthes cases with severe deformity.

​Rope Sign: Due to the severe flattening of the femoral head and the overlapping of sclerotic epiphyseal remnants, a transverse radiopaque line in the form of a "rope" is observed at the junction of the femoral neck and head. This appearance indicates that the caput femoris has collapsed under significant mechanical load and has reached the limits of its remodeling capacity.

Teaching Point: The "Rope Sign" is a pathognomonic finding of severe Legg-Calvé-Perthes disease, representing the radiographic manifestation of a collapsed and flattened epiphysis. In adult patients, recognizing these childhood sequelae is crucial for differential diagnosis, as these structural deformities lead to early-onset secondary osteoarthritis and significant mechanical mismatch.

Multimedia Bonus: For a detailed scroll-through analysis of the CT scans (Coronal & Axial), please visit our video channel. You can observe the depth of the epiphyseal collapse and secondary degenerative changes more clearly in the cross-sectional imaging.

​[Click Here to Watch the CT Case Video]