The Origin Study: A Biomechanical Comparison of Functional Recovery after Custom or Conventional Total Knee Replacement.

: The Origin Study: A Biomechanical Comparison of Functional Recovery after Custom or Conventional Total Knee Replacement

Abstract

Total Knee Replacement (TKR) is one of the most common joint replacement
surgeries worldwide. While clinical outcomes are favourable patients still display
abnormal joint kinematics and kinetics postoperatively. The one-size fits most nature of conventional implant designs may help to explain the lack of functional recovery postoperatively. Custom implants, developed from 3D CT scans of a patient’s knee, have been developed with a view to enhancing functional recovery by restoring the native alignment of the knee joint. The aim of the thesis was to compare the magnitude of functional recovery following conventional and custom TKR 3-months postoperatively.
Twenty-nine patients completed a randomised controlled trial, with 14 patients
assigned to the conventional arm and 15 patients assigned to the custom arm of the trial. Additionally, 15 age matched controls formed a healthy control group.
Participants were asked to walk at a self-selected velocity while a 10-camera 3D
motion capture system recorded kinematic and kinetic data. The lower limb was
modelled using a six-degrees-of-freedom model, in line with the findings of Chapter 3 which demonstrated reduced error for this model compared to the conventional gait model. Spatiotemporal parameters were analysed (velocity, gait cycle duration, stance duration and stride length). Hip, knee and ankle joint angles and moments were combined using the gait abnormality index, a summery metric that describes deviations from the norm, and was compared pre- and 3-months postoperatively between TKR groups and healthy controls.
The study’s findings reported a significant post-operative improvement in the GAI for the custom TKR group between 42% - 75% of the stance phase. Additionally, this improvement was associated with a significant magnitude of change between 55% - 65% of the stance phase. There was no reported significant improvement or magnitude of change in the conventional TKR group. Therefore, this suggested that greater restoration of normal joint angles and moments at the hip, knee and ankle, are evident in the custom TKR group postoperatively. This significant improvement could further aid the restoration of more normal joint kinematics and kinetics throughout the rest of the postoperative recovery period. Notably, though that a number of spatiotemporal, joint angle and moment gait abnormality scores show more recovery is to be made in areas to attain truly normative values, which is unsurprising given 3-months is suggested as the end of the acute phase of recovery.

Date of Award	29 May 2025
Original language	English
Awarding Institution	Edge Hill University
Supervisor	BEN LANGLEY (Director of Studies) & MATT GREIG (Supervisor)