Efficacy analysis of tomosynthesis in the diagnosis of the femoral head osteochondropathy (Legg-Calvé-Perthes disease)

Background: Despite the fact that the prevalence of the femoral head osteochondropathy is 2.9% of all bone and muscle disorders and 25% of the disorders of the hip joint, this problem demands special attention, while late diagnosis could lead to disability of the patient.

Aim: To compare and clarify X-ray symptomatology of Legg-Calvé-Perthes disease found by standard digital radiography and by tomosynthesis.

Materials and methods: Eighty six patients aged from 5 to 12 years with the femoral head osteochondropathy were allocated into two groups: 43  patients from the group  1 were assessed by standard two-plane digital radiography (frontal and Lauenstein projections), whereas 43  patients from the group  2 were assessed by direct plane tomosynthesis only. The investigations were performed with the X-ray machine FDR AcSelerate  200 (Fujifilm, Japan) with the function of tomosynthesis. Radiographic symptoms of the disease were assessed in the subgroups that were identified depending on the disease stage: 24 patients had stage I, 20 – stage II, 20 – stage III, and 22 – stages IV and V.

Results: Standard radiography could not detect any bone abnormalities in any patient with stage I of Legg-Calvé-Perthes disease (n₁ = 12, 100%); however, by means of tomosynthesis, all patients from this subgroup (n₂ = 12, 100%) had minimally increased density on the affected side. In 9  (75%) patients, tomosynthesis showed cystiform remodeling of trabecular structure in subchondral parts of the femoral head of the affected hip, and in 2 (17%) patients, flattening of the inner epiphysis pole was visualized. At stage II of the disease standard radiography showed femoral head compression with widening of the joint space in 8 (80%) patients, absence of subchondral lucency in 6 (60%), and increased density of the femoral head in 4 (40%). In all these patients (n₂ = 10, 100%) tomosynthesis showed signs of intra-articular effusion, in 6 (60%) cases there were areas of osteonecrosis, and in 8 (80%) cases, non-congruent edge of the femoral head and acetabulum. At stage III of the disease, all patients in whom standard radiography was performed (n₁ = 10, 100%) had homogeneous blurring of the femoral head with loss of its bony structure, and with the femoral neck shortening in 6 (60%) of them. With the use of tomosynthesis, all these patients (n₂ = 10, 100%) displayed synovial effusion, in 9  (90%) of cases, head fragmentation, and 7  (70%) patients had shortening and thickening of the femoral neck. Patients with stages IV and V had similar number of symptoms, excluding lateral subluxation of the femoral head (in  63.6% by standard radiography and in 81.8% by tomosynthesis). Accuracy, sensitivity and specificity of standard radiography were 73.3, 70.3, and 71.2%, whereas those of tomosynthesis 91.8, 92.4, and 93.1%.

Conclusion: Tomosynthesis is more accurate, sensitive, and specific and has better positive and negative prognostic values, compared to standard digital radiography. Tomosynthesis can be recommended as a method of choice for diagnosis of the femoral head osteochondropathy.