BACKGROUND AND AIM: According to the World Health Organization (WHO), 4% of the world’s population suffers from osteoarthritis (OA), which means more than 300 million people. Among them, 83% suffer from knee osteoarthritis (KOA) which is the most disabling and painful form of OA. In its early stages, the management of OA consists of trying to reduce or even eliminate the pain to provide more comfort to the patient. However, since pain is a body’s protective mechanism, its suppression could be deleterious to KOA patients’ biomechanics and lead to disease progression’s causes exacerbation. However, pain suppression exact effect on knee biomechanics remains unknown. Thus, the main objective of our research study is to measure and verify whether pain suppression has an impact on the gait mechanics in people with KOA, as quantified by the margin of stability at different instants of gait cycle.
METHODS: Twelve adults with painful patellofemoral osteoarthritis were included, with or without femorotibial osteoarthritis involvement. The experiment took place before and 15 min after pain relief induced by intra-articular injection of 5 mL Xylocaine (1%) into the knee. Participants walked on an instrumented treadmill during 45 seconds at comfortable speed. We processed the ground reaction force data collected from these participants. The center of pressure (CoP), the center of mass (CoM), and the extrapolated center of mass (XCoM) were calculated to estimate the margin of stability (Hof et al., 2007) for different gait cycle instants (ToeOff, HeelStrike, minimal) in medio-lateral (ML) and antero-posterior (AP) directions.
RESULTS: 90% of participants presented 100% pain reduction. For each trial, we isolated the fifteen most reproducible gait cycles for each leg using repeatability of ground reaction forces. A paired student test was performed on each participant to compare pre- and postinjection margin of stability, as well as the absolute value of the pre-/post- evolution, for horizontal and declined walking. After injection of the anesthetic, the margin of stability has significantly changed at ToeOff, at HeelStrike, and for its minimum values, in ML and AP directions, for the global population, in both horizontal and declined walking. However, each subject responded differently following pain suppression. 19,4% (7/36) of the ML margins of stability has significantly decreased in horizontal walking post- injection, while 5,6% (2/36) has significantly increased. In AP, 33,3% (12/36) of the margins of stability has decreased and 19,4% (7/36) has increased. For declined walking, 33,3% (12/36) of the ML margin of stability has significantly decreased in post- injection, while 16,7% (6/36) has significantly increased. In AP, 25% (9/36) of the margins of stability has significantly decreased and 25% (9/36) has increased. Finally, the margin of stability was significantly different at ToeOff, at HeelStrike, and for its minimum values in ML and AP directions for the global population between horizontal and declined walking, both in pre- and post- injection.
CONCLUSION: Considering the total population, there was a significant evolution on ML and AP margin of stability once the pain had been reduced – or eliminate. However, there was no significant general behavior regarding the evolution’s sign. Indeed, when considered individually, some patients presented either increased or decreased margin of stability. This suggests that patients react in different ways when their pain is suppressed. Finally, there was a significant difference on ML and AP margins of stability between horizontal and declined walking, before and after pain suppression.
| Date | 11 Jul 2022 |
|---|
| Original language | French |
|---|
| Awarding Institution | - École de technologie supérieure
|
|---|
| Supervisor | Nicola Hagemeister (Supervisor) & Thomas Robert (Co-supervisor) |
|---|