An 82-year-old female patient presented to our clinics following progressive right hip nontender erythema, warmth, and swelling, with no functional impotence worsening progressively during the last month. She has no fever and no general weakness or loss of weight or any sign of infection or systemic disease.
She has a past medical history significant for hypertension and well controlled diabetes with bilateral total hip arthroplasty for osteoarthritis. On the left asymptomatic side, she underwent a total hip arthroplasty at the age of 60 which was complicated, at age of 78, of periprosthetic infection and was treated with a two-stage revision of total hip arthroplasty. On the right symptomatic side, she underwent total hip arthroplasty at age of 67 which was complicated of nonunion of greater trochanter treated surgically with wiring at age of 74 and posterior dislocation at age of 77 that was treated surgically with a one-stage revision of the acetabulum due to instability. She was completely asymptomatic back then until the last month when she noted erythema, warmth, and swelling of the right hip. There was no history of rheumatoid arthritis, general systemic disease, or chronic infection conditions such as tuberculosis.
Laboratory investigations were unremarkable with a normal WBC count, except for a CRP of 10 ng/mL and an ESR of 45 mm/hr. Radiographs of the pelvis showed bilateral noncemented total hip arthroplasty (metal on polyethylene) with no significant soft tissue changes (Figure 1). No cyst or mass was visualized. A magnetic resonance imaging (MRI) of the pelvis demonstrated a large well-circumscribed hematoma collection with inflammatory changes and cystic areas facing superficially the right hip prosthetic material but not surrounding it with an intermediate signal on T1- and T2-weighted images (Figure 2). The yield of this imaging technique was extremely limited by the artifacts coming from the prosthesis. A tentative of percutaneous puncture under X-ray guidance failed to yield any liquid.
Surgical exploration was performed through an excision of the old lateral wound and by adopting the classic lateral approach of the hip. After cutting the gluteus medius, a large cystic mass formation was noted, overlying the hip joint and extending into it. This well contoured mass is opened revealing a collection of 250 mL of "rice-like" bodies measuring 1 cm each bathing in a clear fluid (Figure 3). It was completely excised and sent to culture and anatomopathological studies. Cultures were sent to look for aerobic, anaerobic, fungal, and acid fast bacilli. There was no evidence of necrotizing or infected or malignant tissue. The hip prosthesis was in place with no evidence of loosening. The wound was copiously irrigated and closed in layers using absorbable suture over drain and stapler on the skin.
All the taken cultures came back negative. The PPD was nonreactive. The RF and the anti-CCP serology were also negative. The microscopic study of the cystic collection and its content revealed a fibrotic synovial nature of cystic wall with fibrinous projections in the cystic cavity similar to the foreign objects qualified as "rice-like" bodies (Figure 4). In fact, they appeared to be fibrinous formation with a collagenous fibrosis. There was no evidence of granulomatosis formation or amyloid deposition. The patient had an uncomplicated postoperative course, the wound healed, and she was asymptomatic at two months of follow-up.