# Alternative alignment clinical study: study protocol for a prospective, randomised, controlled study of the outcomes and cost effectiveness of triathlon CR knee replacement system: traditional philosophy versus alternative alignment philosophy

## TL;DR

This study compares two knee replacement techniques to see if one leads to better patient outcomes and satisfaction.

## Contribution

The study introduces a prospective, randomized trial to evaluate the effectiveness of alternative alignment in knee replacement surgery.

## Key findings

- The study aims to determine if alternative alignment improves functional outcomes at 1 year.
- It will assess multiple short-, medium-, and long-term outcomes to evaluate patient satisfaction.
- The trial is powered to recruit 126 patients, with 63 in each group.

## Abstract

Despite being one of the most successful orthopaedic operation, a number of patients remain dissatisfied after TKR surgery. There has been a recent move by some to change surgical philosophy to aim to replicate the alignment of the patient’s own original knee—known as kinematic or alternative alignment. The purpose of this study is identify if using the alternative alignment technique can lead to significantly improved outcomes when comparted to the traditional alignment technique.

A single centre, randomised control trial, powered to recruit 126 patients (63 in each arm). The primary aim is to identify if the group undergoing TKR using the alternative alignment technique have a significantly improved functional outcome at 1 year when assessed by the minimal clinically important difference of at least 5 points in the Oxford knee score by comparison to the group using traditional alignment technique. Various other secondary outcomes are set out in the main text.

A study examining short-, medium- and longer-term outcomes of alternative alignment is needed to see if outcomes for patients can be improved. This study has the potential to be of great importance in contributing to this question. Limb alignment has focussed on the need to achieve the zero-degree goal of hip, knee and ankle alignment. To achieve real 3D more natural alignment, surgeons have to accept this goal may not be correct. There is a need to achieve pre-arthritic/pre-morbid alignment and to evaluate if this can unlock the potential for improved patient outcomes. A prospective, randomised study with multiple outcome measures can deliver a major contribution to the knowledge base of this subject and influence surgical practice with the aim of improving patient outcomes and satisfaction.

The study was approved by the Wales Research Ethics Committee (IRAS project ID: 225871), and was registered with clinicaltrials.gov (Identifier NCT03196011).

The online version contains supplementary material available at 10.1186/s13018-025-06551-z.