Aspergillus I n f e c t i o n
of Total Knee Arthroplasty P r e s e n t i n g as a P o p l i t e a l C y s t
Case Report and Review of the Literature Kenneth
S. A u s t i n , N~D, * N. N o e l T e s t a , M D , * R o b e r t K. L u n t z , M D , t J e f f r e y B. G r e e n e , M D , * a n d S t e p h e n S m i l e s , M D *
Abstract: Fungal infections have only rarely been reported to occur in patients having
undergone total knee arlhroplasty. This case report documents the first known case of
Aspergillusfumigatus as the offending organism. Its initial presentation as a popliteal cyst further reinforces the known association of popliteal cysts and intra-articular knee pathology. Key words: fungal infections, popliteal cyst, total knee arthroplasty.
Infection is one of the most serious complications of total joint arthroplasty, with overall incidence quoted as being 0 . 5 - 2 %. Reports of fnngal infections complicating total knee arthroplasty (TKA) are rare, with only five d o c u m e n t e d cases of Candida reported.3-6,1 ~,la This is the first k n o w n case of Aspergillus fumigatus complicating TKA.
Twenty-five months after surgery he noticed a painless enlarging mass on the posteriolateral aspect of his right knee (Fig. 1 ). He was without pain, able to ambulate several miles without assistive devices, and able to climb and descend stairs without difficulty. His range of motion was 0 ° - 110 ° with no instability. There was a soft fluid-filled mass (4 x 6 cm) in the posteriorlateral aspect of the knee. Aspiration of the cyst showed 120 ml of cloudy, yellowish fluid. Bacterial cultures of the aspirate were negative; fungal cultures were not sent. The cyst recurred w i t h i n 24 hours. Radiographs, including dye studies of the cyst, were obtained (Fig. 2). The studies were consistent with a posteriolateral cyst but did not demonstrate intra-articular communication. Laboratory studies at this time (white blood-cell count, 5,000; hematocrit, 28; erythrocyte sedimentation rate, 100) were similar to his initial presurgical levels and consistent with his underlying medical conditions. The working diagnosis was a posteriolateral cyst of u n k n o w n etiology but believed to be due to intraarticular pathology. Infection was considered in spite of the negative cultures. Within one m o n t h of its development, the patient u n d e r w e n t removal of the cyst through a lateral incision. The operative finding was a well-encapsulated, fluid-filled lesion that was juxtaposed to the sheath of the biceps femoris tendon. It was noted to c o m m u -
Case Report An 80-year-old m a n had had a righl TKA secondary to longstanding degenerative joint disease. He had a 10-year history of megaloblastic anemia further complicated over the past 5 years by neutropenia of u n k n o w n etiology. He had been on immunosuppressive therapy for the past five years and had required chronic low-dose prednisone (5 mg Q.D.) to maintain his neutrophil count at 2,500-4,000. The patient u n d e r w e n t a right TKA 27 m o n t h s earlier. He recovered from this procedure without incident and had no complaints on his routine follow-up visits at 6 months, 1 year, and 2 years. From the *New York University School of Medicine, New York, New York, and the tCornell University School of Medicine, New York, New York. Reprint requests: N. Noel Testa, MD, 530 First Avenue, New York, NY 10016.
The Journal of Arthroplasty Vol. 7 No. 3 September 1992
Fig. 1. The right knee on initial presentation. Note the posteriorlateral cyst.
nicate with the lateral joint and extend proximally. Pathological study of the specimen revealed a 9.5 × 5 × 3 cm smooth grey-lined cyst. Five of seven intraoperative cultures were positive for Aspergillus fumigatus. The identification of the o r g a n i s m w a s confirmed by the New York State Health Department Mycology Laboratories in Albany, New York. Sensi-
tivity testing revealed high-grade resistance to ketoconazole, 5-fluorocytosine, and itraconazole, and a sensitivity to amphotericin B. Intravenous a m p h o t e r icin B was started at a dose of 30 mg daily. One w e e k after excision of the cyst, the patient u n d e r w e n t irrigation, d e b r i d e m e n t , a n d resection arthroplasty through the original midline, parapatellar arthrotomy. There was minimal joint fluid noted at this time but significant erosion of bone. Of note was an obvious greenish discoloration of the tibial plateau prior to debridement (Fig. 3). The right knee was immobilized in a cylinder cast for 6 weeks. Physical e x a m i n a t i o n at this time revealed moderate instability in all planes with good muscle control. The incision healed per p r i m u m with no signs of infection. Due to the patient's advanced age and our desire to minimize further surgical m o r bidity, he was fitted with a long-leg, c u s t o m - m o l d e d , ischial weight-bearing orthosis. A I 2 - w e e k course of intravenous amphotericin B was completed. The patient is currently full weight-bearing with his orthosis and is functioning well w i t h o u t signs of recurrent infection.
Fig. 2. Radiograph demonstrating the proximal extension of the cyst.
Aspergillus m a y be part of the n o r m a l flora of the upper respiratory tract and can be isolated f r o m numerous other sources, including grains, leaves, and grasses. There are over 300 species, with A. fumigatus being the most c o m m o n . Spores are frequently inhaled; the rarity of disease attests to the strength of
Austin et al.
Fig. 3. Intraoperative photograph of the tibial plateau after cement removal. The reflected patellar tendon is seen of the left. Note the greenish discoloration of the cancellous bone.
host defense mechanisms. 2'~5 It also explains w h y most infections occur in the immunocompromised, such as this patient. ~'~4"15 Aspergillus usually affects the lungs and is k n o w n to spread to contiguous sites, including the ribs and vertebrae. 6,14,~5 There are reports of hematogenous spread, 4,8,14 primary osteomyelitis, 2"~3'14 and seeding of prosthetic cardiac valves. Invasive disseminated Aspergillus is difficult to control and is comm o n l y fatal. 15 Popliteal cysts are k n o w n to be due to preexisting pathology within the knee joint.~ They are usually located medially in association with the semimembranosus, but frequently occur lateraEy under the biceps femoris. 7 Popliteal cysts are reported with increased frequency in patients with rheumatoid arthritis, TKA, and intra-articular infection. ~,7,l o, 12 Several aspects of this case make it unique. It is the first reported case of Aspergillus infection of a TKA. It is also the first case, that we are aware of in which infection of a joint prosthesis presented as an asymptomatic posteriolateral cyst. Once a definitive diagnosis was made, our treatment consisted of removal of the prosthesis, thoro u g h debridement, copious irrigation, and a lengthy course of intravenous antibiotics. 9 This protocol has p r o v e n successful with other fungal infections of arthroplasties. We are in agreement with other authors that a cure can be obtained only with the removal of the infected prosthesis. 3'5'6 It should be stressed that unusual cysts that present after a TKA, even long after its implantation, must
be suspected for possible fungal infection, especially in the i m m u n o c o m p r o m i s e d patient.
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11. Petty W, Bryan RS, Coventry MB, Peterson LF: Infection after total knee arthroplasty. North Am J Med 6: 1005, 1975 12. Schmidt MC, W o r k m a n JB, Barth WF: Dissection or rupture of a popliteal cyst: a syndrome mimicking thrombophlebitis in rheumatic disease. Arch Intern Med 134:694, 1974 13. Simpson MB, Merz WG, Kurlinski JP, Solomon MH:
Opportunistic mycotic osteomyelitis: bone infections due to Aspergillus and Candida species. Medicine 56: 475, 1977 14. Tack KT, Rhame FS, Brown B, Thompson RC: Aspergillus osteomyelitis. Am J Med 73:295, 1982 15. Wyngaarden JB, Smith LH: Cecil's textbook of medicine. 17th edition, p. 1770. WB Saunders, Philadelphia, 1985