key: cord-0006657-0cb7g8ml authors: McCarthy, T. A.; Quinn, B.; Pegum, J. M. title: Inferior dislocation of the patella: an unusual cause of a locked knee date: 2001 journal: Ir J Med Sci DOI: 10.1007/bf03173896 sha: 4a3b7cf3faf95bbf07ec183250e89785a1dbbde3 doc_id: 6657 cord_uid: 0cb7g8ml nan Dear Editor, Inferior dislocation of the patella is unusual without trauma and without rupture of the quadriceps or patellar tendons. A 75-year-old female presented with an acutely locked knee, having developed sudden onset of pain in her right knee while boarding a bus. On examination, the right knee was locked in 40' flexion and attempted movement caused pain. The patella was low lying and there was no evidence of an extensor mechanism rupture. Plain radiographs (see Figure 1 ) and magnetic resonance imaging (M1RI) scan confirmed an inferior dislocation of the patella with intact quadriceps and patellar tendons. Under general anaesthetic, downward pressure was applied to the superior pole of the right patella while extending the knee. This manoeuvre reduced the patellar dislocation and resulted in full range of movement of the knee. The patient made an uneventful recovery. Patellar dislocation usually occurs due to a twisting injury or a direct blow to the knee. Lateral dislocation is the most common type, but there are reports of intra-articular, superior' and inferior' patellar dislocations. Joshi' described the rare inferior dislocation of the patella in which a patient sustained a twisting injury to the knee and the patella displaced out of the groove. The mechanism of dislocation is believed to be that of a supenor pole osteophyte engaging in the intercondylar notch. In our case, this occurred without trauma and resulted in the knee being locked in 40° flexion. Our method of reduction also differed from Joshi's in that downward pressure on the patella was needed to reduce the superior pole osteophyte. Two hours later, she developed a pyrexia of 39.5°C. Blood cultures were taken and intravenous fluids and antibiotics commenced. Despite this, three hours later her temperature increased to 41.2°C with associated tachycardia (140 bpm), hypotension (86/54mmHg) and disorientation. Her white cell count remained normal although her platelet count dropped to 84. Abdominal ultrasound showed minimal thickening of the gallbladder wall with a normal CBD. Abdominal CT confirmed pericystic fluid and focal pneumobilia with a thickened gallbladder but no stones (see Figure 1 ) . Clostridia and streptococci were isolated from peripheral blood cultures. Intraoperative laparoscopic cholangiogram showed CBD dilatation with distal bile duct obstruction. Open cholecystectomy with CBD exploration revealed a distended, oedematous gallbladder and a large CBD sludge cast. A T-tube was inserted and cholangiograrn on day 10 was normal. Postoperatively her pyrexia settled slowly and she was discharged 13 days after admission. Etanercept, a tumour necrosis factor-a (TNFa) p75 receptor analogue, is increasingly used as a second line agent in rheumatoid arthritis. TNFa is a proinflammatory pyrogenic cytokine that modulates the cellular immune response by activating Tcells and promoting endothelial cell adhesiveness. The effect of TNFa antagonism on the clinical course of sepsis is complex. Previous randomised clinical trials of TNFa p55 receptor therapy (lanercept) showed improved outcome following treatment of critically ill patients with severe sepsis. 2 Although no difference in the incidence of infection was reported in placebo-controlled etanercept trials,"' it is not recommended for use in patients with acute or chronic infections. Twenty-four serious and six fatal infections have been reported in etanercept users, although most patients had other risk factors for infection such as poorly controlled diabetes.' Immunosuppressed patients are more likely to have unusual biliary pathogens{ but shock remains a rare presentation of acute cholangitis. 5 Our patient exhibited a rapidly progressive illness with an unusual causative organism despite any other known cause of immunosuppression. Putative effects on biliary sepsis are particularly relevant to the newly established role of anti-TNFa therapy in Crohn's disease due the increased prevalence of Endotoxemia in patients with severe sepsis or septic shock Mechanism of stimulation of interleukin-1-b and tumor necrosis factor a by Mycobacterium tuberculosis components The acute respiratory distress syndrome Inferior dislocation of the patella: an unusual cause of a locked knee References 1. Murakami Y. Intra-articular dislocation of the patella. A case report Superior dislocation of the patella Inferior dislocation of the patella