<>The results from the present study suggest that glucosamine-containing supplements may increase the walking speed through increased stride length and angle of kicking from the ground during steps, which is likely to be associated with alleviated knee pain.

Osteoarthritis (OA) is the most common joint disease, which is one of the causes of Locomotive Syndrome (LS) and causes pain in elderly patients. According to the Research on Osteoarthritis Against Disability, more than 25 million Japanese people aged 40 years and older are estimated to have radiographic knee OA. It has been suggested that knee OA impairs locomotor functions because of the pain, and the biomechanical mechanism of impaired locomotor functions such as walking speed and stride length in patients with knee OA has been investigated. Glucosamine-containing supplements have been used widely for improving knee pain in OA. In previous studies, it has been found that glucosamine-containing supplements “GCQ” or “GCQID” (glucosamine hydrochloride, chondroitin sulfate, type II collagen peptides, quercetin glycosides, imidazole peptides, proteoglycan and vitamin D) were effective for relieving knee pain and/or locomotor functions in randomized, placebo-controlled trials. The effects of thermal and exercise therapies on locomotor functions and their mechanism in patients with knee OA have been elucidated with biomechanical methods, but the biomechanical mechanism of the effects of supplements such as GCQID on locomotor functions has not been reported.

Rationale behind research:

Previous studies have demonstrated that glucosamine-containing supplementation was effective for improving locomotor functions, especially walking speed. However, the biomechanical mechanism of efficacy has not been elucidated. The present study aimed to address this challenge in subjects with knee pain, using a motion capture system.

Objective:

To investigate the biomechanical mechanism for the improving effects of GCQID on locomotor functions in subjects with knee pain.

Study outcomes

• JKOM category I score (VAS score for JKOM knee pain): JKOM is a self-administered, disease-specific measure for knee OA and has demonstrated adequate validity and reliability in people with knee OA in terms of outcomes correlated with health-related quality of life (QOL). The VAS score for JKOM knee pain was measured on a scale from 0 to 100, where 0 indicated no pain and 100 as worst pain ever experienced.
• Total score for JKOM categories II–V (JKOM total score): JKOM total score comprised 25 items that cover four different categories: II: pain and stiffness in knees; III: conditions in daily life; IV: general activities; and V: health conditions. Scores from 25 items were summed, with results ranging from 0 points (no complaint) to 100 points (most severe condition possible).
• GLFS-5 score: GLFS-5 is also a self-administered measure, consisting of five items located in the key domain of construct structure of the GLFS-25, which covers a wide range of issues, from pain to QOL. Three items are graded with 5-point scales from 0 to 4 points, and 5 item scores were summed to produce an overall score with a range of 0 (no impairment) to 20 points (severe impairment).
• VAS score for knee pain in various daily situations: VAS score for knee pain in various daily situations included the pain in each knee on rest, walking or ascending/descending stairs, with scales from 0 to 100, where 0 indicated no pain and 100 indicated the worst pain ever experienced. Questionnaires addressed frequency of trips that involved walking or ascending/ descending stairs, with 5-point scales from 0 (no occurrence) to 4 (frequent occurrence).
• Motor Capture Analysis: For biomechanical mechanism of efficacy for locomotor functions, motion capture analysis in a normal walking state was conducted to obtain data on gait parameters. Subjects took off their shoes and changed into dedicated full-body suits for motion capture. Markers were attached to 30 locations on the body suits. Thereafter, subjects were instructed to walk 10 m two times at their usual speed. The time it took to walk the middle 6 m was measured and normal walking speed was calculated as the primary outcome. The position trajectories of markers attached on the suits of subjects during walking were recorded by a motion capture system at the same time. The values of step length, stride length, cadence, time in the stance phase and the swing phase, and angle of soles and toes for both feet were calculated by analyzing the data of position trajectories, and the average value of the data on both feet was evaluated.

Time Points: Baseline and every 4 weeks to 16 weeks

Motion Capture Analysis: Baseline and at 8 and 16 weeks.

Outcomes

• VAS score for JKOM knee pain, JKOM total score, GLFS-5 score, and all VAS scores for knee pain in various daily situations significantly decreased at week 4 and, thereafter (P<0.05 or P<0.01) compared with baseline. The questionnaire scores reflecting frequency of tripping while walking or ascending/descending stairs significantly decreased at week 8 and thereafter (P<0.05 or P<0.01) compared with baseline.
• Normal walking speed significantly increased at week 16 compared with the baseline (P<0.01). Step length and stride length significantly increased at week 8 and at week 16 compared with the baseline (P<0.05, P<0.01), but cadence was not significantly changed by the intervention. Time in the stance phase significantly decreased at week 8 and at week 16 compared with the baseline (P<0.01), but time in the swing phase was not significantly changed by intervention. Angle of soles at the end of the stance phase significantly increased at week 8 and at week 16 compared with the baseline (P<0.05, P<0.01) and angle of toe at the beginning of the stance phase significantly increased at week 16 compared with the baseline (P<0.01).
• Normal walking speed significantly correlated with stride length, cadence, and angle of sole (P<0.01, r=0.87; P,0.05, r=0.44; and P<0.01, r=0.66, respectively). Stride length correlated with angle of sole at the end of the stance phase and with angle of toe at the beginning of the stance phase (P<0.01, r=0.66; P<0.05, r=0.42, respectively). The VAS score for JKOM knee pain, JKOM total score, and GLFS-5 significantly correlated with each other. JKOM total score and GLFS-5 significantly correlated with stride length (P<0.05, ρ=0.42; P<0.05, ρ=-0.42, respectively).
  

This study showed that GCQID improved functions of locomotion that involve the knee joint, as evidenced by JKOM and GLFS-5 scores, suggesting that GCQID supplementation exerted effects on knee pain in daily life and on QOL. The motion capture analysis revealed that GCQID simultaneously increased normal walking speed and stride (and step) length, but that cadence was not changed. As it has been reported that walking speed is mainly controlled by stride length and cadence, GCQID’s effect of increasing normal walking speed was likely attributable to increased stride length. In addition, GCQID increased the angle of soles at the end of the stance phase, which could indicate increased kicking force of the ground and enhanced driving power. As the change in stride length at 16 weeks was correlated with the change in the angle of soles at the end of the stance phase (r=0.66), it was considered that GCQID might increase stride length through enhanced driving power.

OA patients with knee pain had shorter stride lengths compared with healthy subjects, and the driving power subjects needed to make longer strides could have been restricted because of knee pain. Because the change in stride length at 16 weeks was correlated with changes in JKOM total score and GLFS-5 score, GCQID might increase stride length through alleviated knee pain and improved functions of locomotor system in daily life. In addition, GCQID increased angle of toe at the beginning of the stance phase, which could indicate that the manner of gait control of subjects was changed to one in which toes were raised higher. The change in angle of toe at the beginning of the stance phase at 16 weeks was correlated with the change in stride length (r=0.42), suggesting the possibility of a contribution of increased stride length to higher toe angle by GCQID. As GCQID decreased frequency of tripping while walking, according to the questionnaires, GCQID might actually change the gait in a way that makes subjects less likely to be tripped.