Does Gait Retraining Have the Potential to Slow Osteoarthritis Development and Prolong the Benefits of Knee Realignment Surgery?

Medial knee osteoarthritis (mKOA) and varus knee alignment is associated with altered knee loading. Patients may be offered high tibial osteotomy surgery (HTO) to reduce medial compartment knee joint loading and pain. Gait retraining to alter dynamic knee alignment is proposed as a non-invasive approach to offload the medial compartment. This approach has the potential to provide symptomatic relief prior to surgery and optimise gait along with knee loading post-HTO. This thesis explored the biomechanical gait changes pre-to-post HTO with (i) standard gait to define a baseline change in knee loading following surgery and (ii) with an altered gait style (wide stance, medial thrust, toe out) to provide recommendations that will feed into future gait retraining development.

A systematic review revealed a paucity of information on the consequences of altering gait for patients with mKOA and associated effects on adjacent joints. Gait biomechanics and knee loading features were determined using Inverse Dynamic Modelling where primary metrics of medial compartment knee loading were the two external knee adduction moment peaks (EKAM1 and EKAM2) and predictive musculoskeletal modelling via the Concurrent Optimisation of Muscle Activations and Kinematics (COMAK) to quantify the magnitude and location of internal knee joint contact forces. In addition to the above, Principal Component Analysis and the Cardiff Classifier was used to define the baseline change in gait and knee loading because of HTO surgery.

HTO surgery resulted in biomechanical changes in all three planes at the hip, knee, and ankle joints. Post-HTO, medial knee loading was reduced by ~10% and ~16% when assessed using COMAK at both peaks in stance. HTO surgery reduced the classification belief in mKOA for 20 out of 22 patients, indicating biomechanical improvement occurs due to realignment surgery. Toe out gait pre- and post-HTO reduced EKAM2 (~12% pre and -11% post) and second half of stance internal medial loading peak (~12% pre and ~7% post). Pre-HTO, adopting a toe out gait increased medial internal joint loading in early stance by ~6%. Wide stance gait also reduced medial compartment loading in late stance when adopted pre or post HTO (10-13% reduction in EKAM2 and ~7% reduction in medial internal tibiofemoral joint loading). Medial thrust gait reduced EKAM pre- and post-HTO. The reductions in EKAM were met with significant alterations at the hip and ankle joint moments and kinematics. Contrary to EKAM, medial thrust resulted in a reduced gait speed and conflicting findings with predictive internal joint loading.

This study is the first to investigate the influence of gait alteration on medial compartment loading pre-to-post HTO surgery. It reveals a set of novel clinically important findings and provides preliminary data supporting future development of patient specific gait retraining aimed at clinical translation.