Radiological Category: Musculoskeletal Principal Modality (1): Principal Modality (2): Plain Film CT Case Report # [] Submitted by: Dr. Jason E. Lally, M.D. Faculty reviewer: Dr. Naga Ramesh Chinapuvvula, M.D Date accepted: 15 March 2014
Case History 73 yo F presents to the ER with progressively worsening right hip pain for 4 months. History of right total hip arthroplasty in Mexico 6 years ago. Presented 4 months earlier to a outside hospital for hip pain, was discharged home with pain medication and orthopedic follow-up for hip revision after obtaining medical and dental clearance. Pain became too great, and patient presented to the ER prior to her appointment.
Radiological Presentations
Test Your Diagnosis Which one of the following is your choice for the appropriate diagnosis? Particle disease Infection Stress shielding Metastatic lesion or primary bone/soft tissue tumor
Findings and Differentials Findings: 1. Intact right total hip arthroplasty with massive osteolysis surrounding the femoral stem. 2. No significant amount of cortex found surrounding the stem. 3. Diffuse osteopenia. 4. No obvious acetabular component involvement 5. No obvious effusion or mass lesion. Differentials: Particle disease Infection Stress shielding Metastatic lesion or primary bone/soft tissue tumor
Discussion Mechanical loosening and osteolysis Most common indication for a THA revision, patient is usually symptomatic. Radiologic findings >2mm lucent zone surrounding the prosthesis that can involve the boundary between the bone and prosthesis, cement and bone, or cement and prosthesis. Serial radiographs or immediate postoperative radiographs are most helpful given that all cement is not radio-opaque and radiolucent cement can simulate a lucent zone. Other associated findings include cement fracture and sclerosis at the distal tip of the prosthesis. In arthroplasties that are non-cemented, bead migration may be present. Particle disease Aseptic foreign body granulomatous reaction that occurs when macrophages phagocytize particulate debris leading to cell mediated activation of osteoclasts and inhibition of osteoblasts. Ceramic, stainless steel, titanium alloy, cobalt-chromium alloy and polyethylene have all been indicated. Radiologic findings suggestive of particle disease. Thin slowly progressive line of radiolucency at the interface between bone and cement or bone and prothsethesis. Occasionally, massive destruction of bone surrounding and adjacent to the implant can be seen.
Discussion Infection Organism can take a indolent or aggressive course. Generally, the course for infection is more rapid and aggressive than for particle disease. 1-2% infection rate for primary THA s, increased with revision. Radiologic findings suggestive of infection Bone destruction can be minimal or massive, and indistinguishable from particle disease. Periosteal reaction and soft tissue collections are highly predictive when present. Stress shielding Abnormal stress upon the native bone secondary to the presence of a prosthesis. Leads to bone loss and osteoporosis in regions of decreased load. Radiologic findings suggestive of stress shielding Predominantly involves the superomedial acetabulum and proximal femur. Occurs more commonly with cementless components.
Discussion Metastatic lesions or primary soft tissue/bone tumor Older aged population is at risk for primary cancers and metastatic disease. Rare cause of total hip arthroplasty failure. Soft tissue sarcoma, metastatic lesions and other benign lesions should be considered. NEXT SLIDE: Follow-up CT examination of the right femur.
Radiological Presentations Erase this text box and enter your radiological images here with captions in a text box, as necessary. Do an Insert Duplicate Slide for additional pages of images. Text box must include only the technique factors and information necessary to understand relevance of radiological acquisition. No differentials or diagnosis should be included at this point. Insert additional slides with duplicate style as necessary for presentation. Do not add borders to images. Use animation only if germane to presentation. Erase this box when finished.
Radiological Presentations There is a large 12 x 13 x 20 cm (AP by transverse by craniocaudal) heterogeneously enhancing, hypervascular mass surrounding the right femoral prosthesis involving the quadriceps muscles and gluteus minimus muscle. Hypoattenuating regions within the mass likely represent necrosis. No matrix ossification or calcification is seen within the mass. There are numerous vessels surrounding the mass.
Diagnosis IR guided biopsy was performed. Pathology report: Follicular lesion of thyroid nature, most likely metastatic tumor arising from the thyroid gland or ectopic thyroid tissue. Follow-up thyroid US: Multiple large suspicious nodules present. NM bone scan, CT/PET and CT CAP showed widely metastatic disease involving the bones, brain, and lungs. Diagnosis: Metastatic follicular thyroid cancer 10-20% of well differentiated thyroid cancers are follicular, the other are papillary. Wide age group, with mean age between 50-55 years. Commonly metastasize to the lungs and bones, less commonly to the liver and brain. Patient elected for non-surgical palliative care approach to treatment.
Radiological Presentations Total body bone scan
Radiological Presentations- Thyroid US
Radiological Presentations - MRI
References 1. Keogh CF, Munk PL, Gee R, Lai PC, Marchinkow LO. Imaging of the painful hip arthroplasty. Am J Roentgenol 2003;180:115 20. 2. Mettler FA, Guiberteau MJ. Thyroid, parathyroid, and salivary glands. Essentials of nuclear medicine. 6 th edition. 2012. 111-112. 3. Mulcahy H, Chew FS. Current concepts of hip arthroplasty for radiologists. Part 1. Features and radiographic assessment. AJR 2012; 199:559 569. 4. Mulcahy H, Chew FS. Current concepts of hip arthroplasty for radiologists. Part 2. Revisions and complications. AJR 2012; 199:570 580.