Can Diagnostic and Therapeutic Arthrocentesis Be Successfully Performed in the Flexed Knee?

BACKGROUND/OBJECTIVE: The objective of this study was to determine whether the extended or flexed knee positioning was superior for arthrocentesis and whether the flexed knee positioning could be improved by mechanical compression. METHODS: Fifty-five clinically effusive knees underwent arthrocentesis in a quality improvement intervention: 20 consecutive knees in the extended knee position using the superolateral approach, followed by 35 consecutive knees in the flexed knee position with and without an external compression brace placed on the suprapatellar bursa. Arthrocentesis success and fluid yield in milliliters were measured. RESULTS: Fluid yield for the extended knee was greater (191% greater) than the flexed knee (extended knee, 16.9 ± 15.7 mL; flexed knee, 5.8 ± 6.3 mL; P < 0.007). Successful diagnostic arthrocentesis (≥2 mL) was 95% (19/20) in the extended knee and 77% (27/35) in the flexed knee (P = 0.08). After mechanical compression was applied to the suprapatellar bursa and patellofemoral joint of the flexed knee, fluid yields were essentially identical (extended knee, 16.9 ± 15.7 mL; flexed knee, 16.7 ± 11.3 mL; P = 0.73), as were successful diagnostic arthrocentesis (≥2 mL) (extended knee 95% vs. flexed knee 100%, P = 0.12). CONCLUSIONS: The extended knee superolateral approach is superior to the flexed knee for conventional arthrocentesis; however, the extended knee positioning and flexed knee positioning have identical arthrocentesis success when mechanical compression is applied to the superior knee. This new flexed knee technique for arthrocentesis is a useful alternative for patients who are in wheelchairs, have flexion contractures, cannot be supine, or cannot otherwise extend their knee.

Kaposi Sarcoma as a Cutaneous Vasculitis Mimic: Diagnosis and Treatment.

Painful, palpable purpura usually indicate underlying vasculitis. We report a case of systemic vasculitis treated with immunosuppression that developed painful, vasculitis-like purpuric lesions that progressed rapidly to fulminant Kaposi sarcoma (KS). These purpuric, tumorous lesions resolved completely following the suspension of immunosuppression; however, without immunosuppression, the underlying autoimmunity recurred. This case highlights the potential for early KS to present as a vasculitis mimic or pseudovasculitis that clinicians should keep in mind when purpuric, vasculitis-like lesions develop in an immunosuppressed patient with vasculitis. It is important to recognize these pseudovasculitis lesions as KS rather than recurrent vasculitis so that immunosuppression can be withdrawn.