Intracapsular pressure in children with septic arthritis of the hip.

Elevated intracapsular pressure in the hip causes occlusion of the retinacular vessels and may result in avascular necrosis of the proximal femoral epiphysis (ANPFE) and growth disturbances. Our goal is to study intraarticular pressure in children with septic arthritis of the hip and its potential correlation with body weight, systemic blood pressure and the volume of synovial fluid aspirated from the joint. Thirteen septic arthritis of the hip were studied. Inclusion criteria: pain, limping, fever, leukocytosis, elevated C-reactive protein and ultrasonographic effusion >5 mm. Traumatic, inflammatory, rheumatic or tumoral origin were excluded. Mean age was 3.7 years. Girls were 58%. Mean time to articular drainage was 15 h. Arthrocentesis was performed. An STIC self-calibrating monitoring system with an error of ±1 mmHg was used. Measurements were taken: intracapsular pressure, volume of fluid aspirated, systolic and diastolic pressures and weight. Follow-up was 6.3 years. Descriptive and nonparametric tests were performed: U Mann-Whitney and Kruskal-Wallis. Statistical significance was P <0.05. Mean intracapsular pressure was 50.5 mmHg; fluid aspirated was 2.9 ml; systolic and diastolic pressures were 107.5 and 44.3 mmHg, respectively; weight was 16.2 kg. Intracapsular pressure exceeded 30 mmHg in eight children (61.5%) and was lower than 50 mmHg in 73%. Variables studied had no significance on intracapsular pressure. Complications: coxa magna in three patients (23%) and Harris lines in three (23%). Surgical drainage of septic arthritis of hip must be performed urgently, within the first 24 hours, to reduce the time with high intracapsular pressure and to avoid risk of ANPFE.