Assessment of Implant Fixation and SF-36 for Short Hip-Stems - A Prospective Clinical Study

Assessment of Implant Fixation and SF-36 for Short Hip-Stems - A Prospective Clinical Study

The primary purpose of this study was to evaluate the implant fixation of the NANOS™ Neck Preserving Hip Stem (OHST Medizintechnik AG, distributed by Smith & Nephew GmbH, Marl, Germany) by measuring the migration of the implant using the model-based roentgen stereophotogrammetric analysis (MBRSA).

Inclusion Criteria:

• Subject required primary total hip arthroplasty unilateral or bilateral with a diagnosis of primary and secondary coxarthrosis, dysplasia coxarthrosis and post-traumatic necrosis of the femoral head confirmed by x-ray analysis. For bilateral subjects at least three months between surgical procedures were required.
• Subject was willing to consent to participate in the study and planned to be available for the follow-up examinations.
• Subject had normal motor function of the lower extremities, documented through clinical examinations and lack of signs of a neurological disease with changed motor function.
• Subject was 30 to 65 (inclusive) years of age at time of surgery.

Exclusion Criteria:

• Subject had previous bone or soft tissue surgery of the affected hip except for arthroscopic surgery.
• Subject had a local or systemic infection.
• Subject had previously diagnosed osteoporosis.
• Subject had a femoral neck angle of >145°.
• Subject had a femoral neck angle of <125°.
• Subject had a disease of the cardiovascular system involving particularly reduced load capacity in the everyday life, counting as contraindication of physical stress (American Society of Anaesthesiologists' (ASA) Score 3 or 4).
• Subject had a documented allergy against elements of the implanted device.
• Subject had a neurological disease with changed motor function.
• Subject was pregnant.
• Subject had a Body Mass Index (BMI) > 30.
• Subject suffered from alcoholism or addictive disorders.
• Subject needed a revision hip arthroplasty.
• Subject had an insufficient command of the language to understand patient information and consent.