The Medacta Quadra-P Anteverted Study

Inclusion Criteria: * Subjects suffering from primary hip arthrosis, post-traumatic arthrosis, dysplasia or avascular necrosis of the femoral head, rheumatoid arthritis * Adult subjects between 18 and 75 years of age on the date of surgery * Subjects eligible for primary total hip arthroplasty surgery for whom the anterior Quadra-P femoral component will be implanted according to the indications for use of the implant * Subjects who are willing and able to provide written informed consent for participation in the study. Written informed consent must be obtained prior to surgery. For the anatomical-functional subgroup: \- Adult subjects aged between 18 and 65 years at the date of surgery who have agreed to undergo the gait analysis study. Exclusion Criteria: * Subjects with acute or chronic infection * Subjects with a femoral neck fracture * Subjects with mental conditions that impair their ability to consent to the study, to complete required questionnaires or to complete follow-up visits * Subjects with severe deformities, at the discretion of the surgeon * Subjects with metabolic disorders that may involve bone metabolism for which an uncemented implant would be contraindicated * Subjects with muscular atrophy or neuromuscular diseases * Subjects allergic to the materials used during surgery * Subjects unable or unwilling to provide consent for participation in the study * Any other condition not mentioned in the inclusion criteria