For the past decade, Matija has advised in medico-legal and medical negligence cases as an expert witness. The majority of his medico-legal work has been on behalf of claimants, whereas the majority of medical negligence cases have been on behalf of the defendant (i.e. the NHS).

Areas of expertise within Orthopaedics include:

• Complex Lower and upper limb trauma
• Limb reconstruction including limb lengthening
  
• Non-union surgery lower limb
• Infections of bone and related soft tissue infection
• Osseointegration for amputees
• Total knee replacement including revisions and infections
• Knee arthroscopy and Meniscal repair