PASHiOn: Personalised Against Standard High tibial Osteotomy, a prospective multi-centre randomised controlled trial: Trial Protocol

Knee osteoarthritis (OA) is common, painful, progressive and disabling, and has significant personal and societal burden, particularly in an ageing population. Whilst knee replacement is successful for very late stage disease, it is inappropriate for earlier stages, leaving few effective treatments available for patients in the “treatment gap” between symptom free and late-stage arthritis. High Tibial Osteotomy (HTO) is a proven surgical treatment providing good long-term outcome, reducing pain and improving function. HTO involves changing the alignment of the tibia to correct improper joint loading. Outcomes of HTO surgery are linked directly to the accuracy of the surgical re-alignment with under-correction resulting in worse outcomes. Inaccuracies occur primarily due to limitations of the current planning and surgical technique. A new method (TOKA) has been devised involving personalisation and digital planning. This method uses a custom personalised surgical guide and plate, tailored to the patient.

The aim of the PASHiOn trial is to establish whether digitally planned personalised HTO surgery (TOKA) increases the accuracy of bone correction in comparison to conventional HTO surgery. Embedded within the trial is a nonrandomised pre-RCT technology check and safety assessment of 5 patients (Phase 1), followed by a randomised controlled trial of 88 patients (Phase 2).

During Phase 1 of the clinical investigation, 5 patients fulfilling the inclusion criteria will be recruited and assessed in an identical way to the 88 patients recruited in the main trial, but without randomisation. Recruitment of the remaining patients (Phase 2) will take place after the six-week assessment on the fifth patient is complete and the oversight committee supports progression to Phase 2. Patients in Phase 1 and 2 will be followed up in the same manner for a period of up to 15 months from registration (Phase 1) and randomisation (Phase 2) (12 months from surgery).