NANOS Neck Preserving Hip Stem

Inclusion Criteria: * Inclusion criteria: * Patient requires Primary total hip replacement (THR) to the affected side, unilateral or bilateral. Bilateral only if \>3 months after the first THR * Patient agreed to participate in the MCO study by signing the Informed Consent form. * Age of patient at date of surgery 18 to 65 years * Patient is likely to comply with study follow-up requirements Exclusion criteria: * Previously failed endoprosthesis and /or THR components in relevant hip * Patient has proven osteoporosis * Pronounced coxa valga with a femoral neck angle \> 145º * Pronounced coxa vara with a femoral neck angle \< 125º * History of infection in the affected joint; systemic infections * Grossly insufficient femoral or acetabular bone stock in the involved hip where a revision cup is indicated * Spinal disease with neurologic movement disorders * Alcoholism or addictive disorders * ASA score is 3 or 4 * Body mass index (BMI) \> 30 * Patient is pregnant or being pregnant during follow up intervals * Patients understanding of the language is insufficient for understanding the Patient Information and Consent