Personalised HTO Versus Generic HTO Virtual Clinical Trial
Condition: Osteoarthritis, Knee
MeSH terms: Osteoarthritis; Osteoarthritis, Knee
Study type: Observational

Summary: 
      High Tibial Osteotomy (HTO) is an alternative to knee replacement in suitable patients with
      early knee osteoarthritis (OA), it is particularly suited to patients with single compart
      disease who otherwise would be suitable for unicompartmental knee replacement (UKR). OA of
      the knee is very common and increasing driven by the ageing of the population. The current
      limitations of HTO are related to the difficulty of achieving the desired correction due to a
      challenging surgical technique and soft tissue irritation due to the use of generic
      stabilisation plates. This study will examine the safety equivalence of a new patient
      specific HTO process which has patient specific 3D printed plates, i.e. personalised HTO
      plates, with the existing most commonly used HTO procedure using the Tomofix generic HTO
      plate. Importantly this study will be undertaken as a Virtual Trial, existing anonymised 3D
      imaging data will be used to create the virtual patient cohort. This cohort will receive both
      procedures, which for this type of procedure is only possible in a virtual scenario.

      The main question to be addressed is: "Is the personalised HTO procedure as safe as the most
      commonly used existing generic HTO procedure?". In this context safety concerns the
      mechanical loads placed upon the tibia and the support plate.

      The interventions will all be made on computer models, the 3D imaging data will be used to
      create the intact (un-operated) models of the subject tibias. Each model will then be
      virtually operated upon, with both the personalised and generic HTO procedures. The models
      will then be loaded with physiological loads experienced during function and the mechanical
      states compared.
    

Detailed description: 
      Ethical approval was obtained to use CT scans of 30 patients with moderate to severe knee
      arthritis (REC reference: 17/HRA/0033, Royal Devon & Exeter National Health Service [NHS],
      UK).

      The CT data will be used to generate the 3D geometry of each patient's proximal tibia. The
      osteotomy correction angle required for each patient such that the altered mechanical axis
      will pass through a point 62.5% of the distance from medial to lateral tibial plateau.
      Virtual HTO surgery will be performed on each patient to alter the mechanical axis of the
      knee by creating an opening wedge osteotomy.

      After the virtual surgeries are performed, each virtual patient will be duplicated. One copy
      will have the osteotomy stabilised using a Generic plate and the other using a Personalised
      plate, thus forming the two arms of the trial.

      For each participant in each arm finite element (FE) models will be created, and loads
      applied simulating walking, sit to stand and squatting. Four healings stages will be
      considered, stage 1 being immediately post-operation (this will not be modelled), stage 2
      representing 2 weeks post-operation, stage 3 representing 6 weeks and stage 4 representing 12
      weeks. The mechanical loads in the plates, and around the screw locations in the bone, will
      be established by solving these finite element models.
    

Intervention name(s): Opening wedge high tibial osteotomy; Personalised subject specific custom HTO plate; Generic HTO plate
Intervention type(s): Procedure; Device; Device
Intervention description(s): Realignment of knee by creating an opening wedge osteotomy in the upper part of the tibia. Since this is a virtual trial, the virtual patients were duplicated and enrolled into both arms; Subject specific custom plate for stabilizing an open wedge HTO; Generic plate for stabilizing an open wedge HTO
Other intervention name(s): HTO; Personalised plate; Generic plate
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Population was recruited from waiting list of patients with knee OA
      
Keywords: virtual clinical trial; high tibial osteotomy; 3D; computer simulation; finite element analysis; medial unicompartmental knee osteoarthritis