The treatment goal is to rapidly make a diagnosis and establish an effective arthroscopic therapy in order to allow the hip joint to develop normally throughout childhood with respect to anatomical and functional development. Coxarthritis suspected of being septic arthritis No experience with arthroscopy, osteomyelitis of the dorsal femoral neck requiring an intervention. Relative contraindication: absence of cannulated systems. Arthroscopic lavage of the hip joint, including revision of the femoral neck and debridement of osteomyelitis of the femoral neck with placement of an antibiotic carrier if necessary. The arthroscopy is performed using the two portal technique, placing the patient supine on a normal operation table (traction table not required). Drain for 2-3 days with mobilization after removal of the drainage. A second look arthroscopy is not normally planned but may become necessary in cases without improvement of the clinical or laboratory test parameters and after follow-up magnetic resonance imaging (MRI). The two portal hip joint arthroscopy using an irrigation volume of 6-9 l is an efficient minimally invasive method to safely treat septic arthritis of the hip joint with or without concomitant femoral neck osteomyelitis. It is associated with low morbidity and offers all advantages of an arthroscopic procedure. Out of 23 children 19 could be sufficiently treated by a single arthroscopic lavage of the hip joint. In three patients an additional osseous component required a second intervention. Out of 23 children 22 achieved an excellent Harris hip score, with one girl only achieving a moderate outcome. The 22 children had an unrestricted hip function at follow-up and could return fully to previous activity levels.