Importance of Restoring Biomechanical Correct Hip Anatomy During Total Hip Arthroplasty
Condition: Osteoarthritis
MeSH terms: Osteoarthritis
Study type: Interventional

Summary: 
      The purpose of this prospective, randomized study is to evaluate the importance of restoring
      the exact individual hip biomechanics during total hip arthroplasty.
    

Detailed description: 
      This prospective, controlled and randomized study aims at evaluating the correlation between
      postoperative hip prosthesis migration and the achieved exactness of biomechanical
      restoration of hip mechanics during total hip arthroplasty (THA). The main objective is to
      find out how close the result from the surgery can come to a preferred prosthesis position
      and whether this makes any difference in terms of loosening, functionality and quality of
      life for the patient. The prosthesis positioning is performed with either (1) computer
      assisted navigation, (2) instrumented hip guide measuring devise alignment technique or (3)
      conventional non-instrumented measuring technique. The ABG II stem system (Stryker) will be
      used in the modular version for group 1 and 2 and the non-modular version in group 3. Before
      each operation the investigators will perform exact measurements of anatomical variables
      using preoperative radiographs (maximum 8 weeks old) and computed tomography images
      (CT)(taken 3-4 weeks preoperatively). While applying these measurements the investigators
      will try to preserve the patient´s individual biomechanical situation, most often as compared
      to the healthy contralateral hip. The variables to be analysed are anteversion of the femoral
      neck, offset and leg length. This preoperative hip analysis combined with the use of a
      templating system will give the data needed for component choice and exact positioning of the
      ABG II hip prosthesis. 75 patients will be randomized into the three groups (25+25+25). The
      patients will be followed with RadioStereometric Analysis (RSA) for two years (directly
      postoperatively, 14 days, 3 months, 1 year and 2 years). There will be a second CT scan 1
      year postoperatively to measure the actual achieved position. In completion hip specific and
      general health questionnaires will be used to evaluate patient satisfaction and outcome. All
      patients will be subject to 3-Dimensional (3-D) gait analysis 3-4 weeks prior to surgery and
      after one year. The results of the gait analysis will be correlated to the achieved
      restoration of the hip anatomy and biomechanics. The investigators aim is to improve the
      fundamental understanding of the hip biomechanics in patients undergoing THA. Will physical
      performance improve when the individual hip biomechanics is better restored, and in which way
      and to what extent?
    

Intervention name(s): GF hip guide; Stryker Navigation System; ABG II modular femoral component
Intervention type(s): Procedure; Procedure; Device
Intervention description(s): Using GF hip guide to measure and control the peroperative positioning of the hip stem; Using Orthomap Modular Hip Software to navigate the operation; A hip prosthesis made by Stryker. It has the same basic shape as the ABG II femoral component but has a modular neck system allowing it to better follow the patient specific hip anatomy regarding offset, varus-valgus angle and rotation in the anteroposterior plane.
Other intervention name(s): Instrument designed by the investigators; Stryker Orthomap Hip Navigation System; ABG™II modular Cementless Hip System
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Radiostereometric Analysis (RSA); Total hip arthroplasty (THA); Hip anatomy; Hip biomechanics