SUSTAINED LIMB‐LEVEL LOADING: A GROUND REACTION FORCE PHENOTYPE COMMON TO INDIVIDUALS AT HIGH‐RISK FOR AND THOSE WITH KNEE OSTEOARTHRITIS

OBJECTIVE To compare the vertical (vGRF), anterior‐posterior (apGRF) and medial‐lateral (mlGRF) ground reaction force (GRF) profiles throughout the stance phase of gait: 1) between individuals 6‐12 months post anterior cruciate ligament reconstruction (ACLR) and uninjured matched controls; and 2) between ACLR and individuals with differing radiographic severities of knee osteoarthritis (KOA) defined as Kellgren and Lawrence (KL) grades KL2, KL3, and KL4. METHOD A total of 196 participants were included in this retrospective cross‐sectional analysis. Gait biomechanics were collected from individuals 6‐12 months post‐ACLR (n=36), uninjured controls matched to the ACLR group (n=36), and individuals with KL2 (n=31), KL3 (n=67), and KL4 OA (n=26). Between‐group differences in vGRF, apGRF, and mlGRF were assessed in reference to the ACLR group throughout each % of stance phase using a functional linear model. RESULTS The ACLR group demonstrated lesser vGRF and apGRF in early and late stance compared to the uninjured controls, with large effects ( d range: 1.35‐1.66). Conversely, the ACLR group exhibited greater vGRF (87‐90%; 4.88%BW; d =0.75) and apGRF (84‐94%; 2.41%BW; d =0.79) than the KL2 group in a small portion of late stance. No differences in mlGRF profiles were observed between the ACLR and either the uninjured controls or the KL2 group. The magnitude of difference in GRF profiles between the ACLR and OA groups increased with OA disease severity. CONCLUSION Individuals 6‐12 months post‐ACLR exhibit strikingly similar GRF profiles as individuals with KL2 KOA, suggesting both patient groups may benefit from targeted interventions to address aberrant GRF profiles.