Artificial hemipelvic displacement treatment for bone hydatid disease.

To the Editor: Hydatidosis is a parasitic tapeworm infection caused by Echinococcus, which is a rare anthropozoonosis that seldom affects bone.

A 35-year-old female patient from Qinghai province was admitted to Peking University First Hospital who complained about progressive paracoxalgia and lower limb weakness of the left leg for about 14 years after falling from a standing height. Pathologic fracture of femoral neck was diagnosed and malunion after conservative treatment was found. Four years before she was admitted to our hospital, the patient found that several masses revolving around her left hip joint grew up with the unrelieved pain after analgesic therapy. Biopsy was made 2 years ago and hydatid disease was definitely diagnosed. Plain radiograph and computed tomography (CT) revealed pelvis and femoral head of the left leg were severely collapsed by hydatid cysts. Magnetic resonance imaging (MRI) showed even muscles around the hip joint were invaded by tens of hydatid cysts [Figure 1A–C].

Figure 1

X-ray (A) and CT (B) revealed that pelvis and femoral head of the left leg were severely collapsed by hydatid cysts. MRI (C) revealed that muscles around the hip joint were invaded by tens of hydatid cysts. Hydatid cysts were explored during the surgery (D), and the left pelvis and proximal femur that were severely collapsed by hydatid cysts were incised (E). X-ray revealed the fixed prosthesis after 2 years follow-up (F). CT: Computed tomography; MRI: Magnetic resonance imaging.

Artificial hemipelvic displacement was demanded to recover the function of hip joint because of the severe collapse of the pelvis and femoral head. Two-step operation was considered as the best treatment regimen. First, hydatid cysts in the muscles around the joint were incised carefully. Three months after the debridement, collapsed pelvis and proximal femur were removed and the joint was displaced with artificial hemipelvis and hip joint [Figure 1D–F]. Oral chemotherapy (albendazole) was executed everyday as a combination strategy in the perioperative period. At 6 months follow-up after the surgery, her left leg had regained fully weight bearing. In the 2 years of follow-up, she was not complained about any discomfort.

Hydatid disease is a parasitic infestation in which liver and lung are commonly affected. Bone involvement is detected in approximately 3% of cases, and the ribs, pelvis, and skull are the most frequently involved bones.[ In our case, hydatid cysts were widely shown in left pelvis, femoral head and surrounding muscles. It is a very rare lesion location reported in this kind of disease.

Image examination is the main basis for diagnosis, including ultrasonography, plain radiographs, MRI, and CT scans. MRI is the most helpful examination, especially when soft tissue and spine are affected.[ However, it is very difficult to diagnose bone hydatid cyst disease by radiology because the test results are non-specific. Casoni test and indirect hem-agglutination test are the diagnostic options available for hydatid disease.[

The treatment regimen for this disease includes a careful complete open surgical excision of cysts and removal of the affected bones, combining with Albendazole chemotherapy for at least 2 years or lifelong treatment.[ In our patient, due to the complete loss of power for left hip flexion caused by severe collapse of the pelvis and femoral head, artificial hemipelvic displacement is needed to recover the function of hip joint. To our knowledge, this is the first reported case that suffering long duration, rare location, and severe collapse which must be treated with artificial hemipelvic displacement.

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Conflicts of interest

None.