Baseline characteristics of participants by group
| Motion control shoes (n=18) | Neutral shoes (n=22) | |
| Age (years) | 64.6 (7.2) | 64.2 (7.2) |
| Gender, n (%) | ||
| Female | 11 (61) | 13 (59) |
| Male | 7 (39) | 9 (41) |
| Symptom duration (years) | 11.6 (7.8) | 11.1 (8.0) |
| Height (m) | 1.7 (0.1) | 1.7 (0.1) |
| Body mass (kg), median (IQR) | 89 (75–95) | 89 (81–106) |
| Body mass index (kg/m2), median (IQR) | 31.4 (27.6–35.4) | 31.2 (27.8–33.9) |
| Unilateral knee osteoarthritis symptoms, n (%) | 3 (17) | 7 (32) |
| Radiographic disease severity, n (%)* | ||
| Grade 2 (mild) | 2 (11) | 3 (14) |
| Grade 3 (moderate) | 8 (44) | 10 (45) |
| Grade 4 (severe) | 8 (44) | 9 (41) |
| Radiographic knee alignment (degrees)† | 188.7 (6.3) | 188.1 (5.5) |
| Foot Posture Index classification, n (%)‡ | ||
| Supinated | 0 (0) | 1 (5) |
| Neutral | 3 (17) | 8 (36) |
| Pronated | 15 (83) | 13 (59) |
| Foot mobility magnitude (mm)§ | 7.7 (3.5) | 7.7 (2.5) |
| Navicular drop (mm)§ | 6.5 (4.4) | 6.3 (3.0) |
| Currently employed, n (%) | 10 (56) | 11 (50) |
| Current drug/supplement use, n (%)¶ | 15 (83) | 18 (82) |
| Paracetamol combinations | 11 (61) | 15 (68) |
| Non-steroidal anti-inflammatories | 8 (44) | 10 (45) |
| Topical anti-inflammatories | 8 (44) | 4 (18) |
| Oral corticosteroids | 0 (0) | 0 (0) |
| Oral opioids | 0 (0) | 0 (0) |
| Arthritis Self-Efficacy Scale** | 6.4 (2.1) | 6.3 (1.5) |
| Cointerventions used in the last 6 months, n (%) | ||
| Land-based exercise | 12 (67) | 13 (59) |
| Heat/cold treatment | 11 (61) | 7 (32) |
| Massage | 8 (44) | 11 (50) |
| Knee braces | 8 (44) | 8 (36) |
| Manual therapy | 3 (17) | 8 (36) |
| Orthotics/arch supports | 2 (11) | 2 (9) |
| Hydrotherapy | 3 (17) | 4 (18) |
| Usual shoes overall motion control feature score, mean (SD)†† | 6.2 (3.2) | 6.4 (2.7) |
| Expectation of treatment, before randomisation, n (%) | ||
| No change | 0 (0) | 0 (0) |
| Mild improvement | 2 (11) | 3 (14) |
| Moderate improvement | 10 (56) | 16 (73) |
| Large improvement | 6 (33) | 3 (14) |
| Complete recovery | 0 (0) | 0 (0) |
| Expectation of treatment, after shoe allocation, n (%) | ||
| No change | 0 (0) | 0 (0) |
| Mild improvement | 1 (6) | 2 (9) |
| Moderate improvement | 12 (67) | 13 (59) |
| Large improvement | 5 (28) | 6 (27) |
| Complete recovery | 0 (0) | 1 (5) |
Data reported as mean (SD) unless otherwise stated.
IQR in 25th–75th percentile.
*Using the Kellgren and Lawrence grading system.
†Measured as anatomical axis from standing radiograph, with 180° indicating neutral alignment, <180° varus alignment and >180° valgus alignment.
‡Scored from −12 to 12; scores <0 indicate supinated foot posture, 0–5 neutral foot posture and >5 pronated foot posture.
§Higher values indicate greater mobility/drop.
¶Defined as at least once per week in the last 6 months.
**Scores range 1–10, with higher scores indicating higher self-efficacy.
††Measured using the Footwear Assessment Tool; scores range 0–11, with higher scores indicating more motion control features.