E07. HYPERTROPHIC PULMONARY OSTEOARTHROPATHY AFTER UNICOMPARTMENTAL KNEE ARTHROPLASTY

Abstract

Background: A case of hypertrophic pulmonary osteoarthropathy (HPOA) after unicompartmental knee arthroplasty (UKA) is herein reported. Methods: 61-year-old man with bilateral knee osteoarthritis underwent left UKA in another hospital. Severe pain in his left knee and mild pain in his right knee began at the age of 66-years. The operator of UKA found no remarkable change in his UKA, and non-steroidal antiinflammatory drugs (NSAIDs) were administrated. He consulted our hospital because of no-effect with conservative NSAIDs therapy. Results: Physical examinations revealed none of swelling, local heat, and instability in his left knee. The passive range of motion of his left knee was 0-140°. X-ray examination revealed no radiolucent line around femoral and tibial components, and component loosening was not observed. The laboratory investigations revealed white blood cell count of 9,700/μL, C-reactive protein of 2.00 mg/dL, matrix metalloproteinase- 3 of 60.0 ng/mL, rheumatoid factor of 57 U/mL, anticitrullinated peptide antibody of<0.6U/mL, sialylated carbohydrate antigen KL-6 of 1,520 U/mL. To rule out the infection of UKA, aspiration of his left knee was performed, however, no joint fluid was observed. Isotope bone scan suggested increased uptake along the shaft of the distal femur, the tibia, and the ankle on both sides without uptake around the components. X-ray and computed-tomography (CT) scan of the knees showed periosteal reaction along the distal femur near the femoral component. He also showed digital clubbing. These findings suggested the diagnosis of HPOA. X-ray and CT scan of chest confirmed a mass in the right lower lobe. Biopsy confirmed an adenocarcinoma with class IV. Multiple brain metastases with upper and lower limb palsy were observed 3-months later. Despite of the radiation therapy for whole brain, he was dead 4-month-later. Conclusion: HPOA is a disabling condition that may occur secondary to primary lung cancer. It is characterized by digital clubbing, arthlagia, and periostosis of the tubular bones. The pain associated with HPOA can be disabling and often refractory to conventional analgesics. The pain after arthroplasty usually associated with infection, insufficiency fracture, implant failure including aseptic loosening, arthritis, and soft tissue origin. Although orthopaedic surgeons usually check the operated site, whole body, such as the chest, examination is rare. This pain after UKA was quite rare case after arthroplasty, however, HPOA is an important differential diagnosis for the pain that is disabling and often refractory to conventional analgesics.