Evaluation of X-ray, Acetabular Guides and CT in THR
Condition: Total Hip Replacement
Study type: Interventional

Summary: 
      Total hip replacement is one of the most successful surgical procedures of modern times, with
      over 80,000 performed each year in the UK. However, up to 5% of all primary hip replacements
      need to be revised within the first 10 years, and in many cases malposition of the acetabular
      (hip socket) component is implicated in the early failure.

      The standard method of positioning the acetabular component is for the surgeon to be guided
      by a combination of the visible anatomical landmarks within the surgical field, and the wider
      environment of the operating theatre. The advent of 3D printing has led to the development of
      custom-made surgical guides which can be used during surgery, in order to assist the surgeon
      in the positioning of instruments and devices. These surgical guides are manufactured based
      on CT or MRI imaging, and are designed to clearly indicate to the surgeon the desired
      location and orientation of bony cuts and implant positions.

      This study will test the hypothesis that an acetabular alignment guide combined with
      three-dimensional CT-based planning using the Corin OPS™ (Optimised Positioning System),
      provides more accurate component alignment following primary total hip replacement compared
      with the current standard treatment, with the aim of improving patient outcomes and reducing
      the risk of complications of total hip replacement.
    

Detailed description: 
      Total hip replacement is one of the most successful surgical procedures of modern times, with
      over 80,000 performed each year in the UK. The vast majority of patients experience dramatic
      pain relief and improvement in function for many years. Despite this, however, there remains
      a significant risk of complications, including dislocation, leg length discrepancy,
      squeaking, and premature wear and failure of the implant. It is known that such complications
      are more likely to occur if the acetabular component is incorrectly positioned during the
      surgery. Up to 5% of all primary hip replacements need to be revised within the first 10
      years, and in many cases malposition of the acetabular (hip socket) component is implicated
      in the early failure.

      The Corin OPS™ offers such a custom-made acetabular alignment guide. Prior to the patient's
      surgery, a CT scan of the patient's pelvis & legs is performed, and the images are used to
      produce a 3D computer model of the patient as they stand with a "virtual" hip replacement in
      place. Four additional X-rays of the pelvis and lumbar spine are also taken, with the patient
      adopting various predetermined "functional" positions (e.g. sitting in a chair, about to
      stand up). From these X-rays, the changes in the pelvic and femoral orientations can be
      measured for these functional positions. This data is then used to drive a simulation of the
      movement of the 3D computer model. The orientation of the components of the virtual hip
      replacement are then adjusted to optimise the biomechanical function of the joint. Once the
      proposed implant positions have been reviewed and approved by the surgeon, a custom-made
      acetabular orientation guide is 3-D printed and sterilised. During the surgery, this guide is
      fitted into the patient's acetabulum prior to implanting the components. Using a simple
      system of two sterile laser pointers, the orientation indicated by the guide can then be
      reproduced when the definitive acetabular component is implanted. There is no published data,
      however, on the accuracy of acetabular component positioning using this particular method.
      The standard of care in the UK for acetabular component positioning is the "freehand
      technique", where the surgeon is to be guided by a combination of the visible anatomical
      landmarks within the surgical field, and the wider environment of the operating theatre. It
      is important that the impact of this acetabular guide on acetabular component positioning be
      assessed in order to determine whether this intervention is likely to improve patient
      outcomes and reduce the risk of complications of total hip replacement.
    

Intervention name(s): Corin OPS™; 2D X-ray templating technology
Intervention type(s): Device; Other
Intervention description(s): The OPS Dynamic Hip Analysis is a computer software package used to generate simulations of a total joint replacement from patient imaging. The dynamic simulation is used for operative planning, including implant selection, sizing and placement; and to create custom instruments or delivery specifications referencing the patient's anatomy and bio-mechanics. The simulation can also be used for the post-operative evaluation of joint performance.; Standard care where hip replacement is planned using 2D X-ray templating software
Other intervention name(s): Standard Care
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Single-centre, patient-assessor blinded, parallel-group, randomised-controlled trial
Masking: Single (Outcomes Assessor)
Primary purpose: Device Feasibility
Keywords: hip replacement; acetabulum; anteversion; position; guide