Characteristics of included studies
| Authors and year | n (M:F) | Group demographics (mean (SD)) | OA severity (frequency) | Inclusion criteria | Intervention | Control condition | Methodological quality score (/27) |
| Abdallah 30 | 21 (0:21) | Age (y): 54.1 (7.4) Height (m): 1.57 (0.06) Mass (kg): 84.2 (8.8) | K/L grade (NA) | Radiographic evidence; medial pain on most days in the past month; pain of at least 30 mm on 0–100 mm VAS following physical activities during the previous 2 days and at least one of the following items: 50 years, morning stiffness >30 min or crepitus on active knee joint motion | LWAS | Neutral insole with medial arch support in flexible lab shoe | 20 |
| Butler et al 31 | 20 (9:11) | Age (y): 63 (6) BMI (kg/m2): 33.4 (7.8) | K/L grade (NA) | Knee pain during walking ≥3 on VAS; ≥K/L grade 2; medial compartment; able to walk independently for at least 20 min without an assistive device | LWI | Neutral insole in a standardised lab shoe | 21 |
| Butler et al 32 | 30 (13:17) | Age (y): 63.1 (6.8) BMI (kg/m2): 33.8 (6.9) | K/L grade 2 (9) K/L grade 3 (9) K/L/ grade 4 (11) | Average knee pain >3 on VAS during weight-bearing activities in past 2 weeks; ≥K/L grade 2; medial compartment | LWI | Neutral insole in a standardised lab shoe | 21 |
| Chapman et al 8 | 70 (43:27) | Age (y): 60.3 (9.6) Height (m): 1.69 (0.09) Mass (kg): 87.3 (18.5) BMI (kg/m2): 30.5 (4.9) | K/L grade 2 (17) K/L grade 3 (25 of those with K/L data) | Age between 40 and 80 years; medial tibiofemoral OA; K/L grade 2 or 3 on radiograph; medial greater than lateral joint space narrowing; at least mild pain when walking on a flat surface assessed by the KOOS | LWI | Flat, thin soled lab shoe | 20 |
| Duivenvoorden et al 14 | 42 (14:28) | Age (y): 54 (7) BMI (kg/m2): 30 (5) | K/L grade 1 (15) K/L grade 2 (8) K/L grade 3 (18) K/L grade 4 (1) | Pain and tenderness over the medial joint space; radiographic evidence; K/L grade one or higher; varus malalignment | LWI | Unspecified | 21 |
| Esfandiari et al 19 | 23 (NA) | Age (y): 46.7 (5.0) BMI (kg/m2): 31.6 (4.1) | K/L grade (NA) | Over 40 years of age; radiographic medial compartment knee OA (ACR); pain worse than 3/10 on a VAS; presence of osteophytes in the joint space | LWI | Gymnastic shoes | 22 |
| Hatfield et al 16 | 26 (4:22) | Age (y): 64.0 (8.0) Height (m): 1.61 (0.98) Mass (kg): 70.6 (13.8) BMI (kg/m2): 27.2 (4.2) | K/L grade 2 (16) K/L grade 3 (10) | Symptomatic unilateral or bilateral radiographically diagnosed medial tibiofemoral compartment OA; ≥K/L grade 2; flat feet (defined as foot posture index of +4 or greater in at least 4/6 measures) | LWI; LWAS | Standardised lab sandal | 21 |
| Hinman et al 33 | 13 (6:7) | Age (y): 59.7 (6.2) Height (m): 1.69 (0.14) Mass (kg): 81.0 (20.4) | K/L grade 2 (7) K/L grade 3 (6) | Aged over 50 years; reported knee pain on most days of previous month; medial tibiofemoral osteophytes on radiograph; average knee pain ≥3 on an 11-point numeric scale when walking | LWI | Participant’s usual footwear | 20 |
| Hinman et al 34 | 40 (16:24) | Age (y): 64.7 (9.4) Height (m): 1.64 (0.09) Mass (kg): 79 (12) BMI (kg/m2): 29.6 (4.2) | K/L grade 1 (3) K/L grade 2 (10) K/L grade 3 (11) K/L grade 4 (16) | Aged over 50 years with knee OA; reported knee pain on most days; medial tibiofemoral osteophytes on radiograph; average knee pain > 3 on an 11-point Likert scale when walking; knee pain when walking two blocks and/or climbing stairs | LWI | Participant’s usual footwear | 19 |
| Hinman et al 3 | 20 (8:12) | Age (y): 63.5 (9.4) Height (m): 1.69 (0.07) Mass (kg): 83.1 (14.2) | K/L grade 2 (8) K/L grade 3 (12) | Aged over 50 years; reported knee pain on most days of previous month; medial tibiofemoral osteophytes on radiograph; average knee pain ≥3 in the past month on an 11-point numeric scale when walking | LWI | Participant’s usual footwear | 19 |
| Hinman et al 7 | 73 (28:45) | Age (y): 63.3 (8.4) Height (m): 1.67 (0.09) BMI (kg/m2): 27.7 (3.6) | K/L grade 2 (41) K/L grade 3 (32) | Aged over 50 years; reported knee pain most days of previous month; demonstrated medial tibiofemoral osteophytes on radiograph; knee pain >3 on 11-point Likert scale during walking | LWI | Participant’s usual footwear | 21 |
| Hinman et al 17 | 21 (9:12) | Age (y): 68.5 (10.4) Height (m): 1.7 (0.9) Mass (kg): 79.2 (16.2) BMI (kg/m2): 28.3 (5.2) | K/L grade 2 (9) K/L grade 3 (9) K/L grade 4 (3) | Aged over 50 years; reported knee pain on most days of previous month; medial tibiofemoral osteophytes on radiograph; average knee pain ≥3 in the past month on an 11-point numeric rating scale when walking | MAS | Standardised lab shoes | 20 |
| Hsu et al 15 | 10 (0:10) | Age (y): 66 (5.3) Height (m): 1.56 (0.05) Mass (kg): 60 (5.1) | K/L grade (NA) | Bilateral medial knee OA; K/L grade 2 or 3 in both knees; ability to walk independently | LWI | Barefoot | 21 |
| Jones et al 35 | 51 (29:22) | Age (y): 59.6 (8.9) Height (m): 1.69 (0.08) Mass (kg): 90.3 (17.9) BMI (kg/m2): 31.6 (5.1) | K/L grade 2 (22) K/L grade 3 (29) | Aged 45 years or greater; K/L grade 2 or 3 on radiograph; medial greater than lateral joint space narrowing; at least mild pain when walking on flat surface during the last week assessed by the KOOS | LWI; LWAS | Standardised lab shoe | 19 |
| Jones et al 26 | 70 (43:27) | Age (y): 60.3 (9.6) BMI (kg/m2): 30.5 (4.9) | K/L grade mean 2.6 (SD: 0.5) | Aged 45 years or greater; medial tibiofemoral OA; K/L grade 2 or 3 on radiograph; medial greater than lateral joint space narrowing; at least mild pain when walking on a flat surface during the last week assessed by the KOOS | LWI; LWAS | Standardised lab shoe | 20 |
| Kakihana et al 36 | 13 (0:13) | Age (y): 63.3 (5.6) Height (m): 1.53 (0.06) Mass (kg): 57.3 (10.3) | K/L grade (NA) | Age 50 years or greater; knee pain for at least 6 months; bilateral knee OA with osteophytes indicated by radiograph; initial stiffness <30 min in the morning or crepitus on active motion of the knee | LWI | Neutral insole attached to participant’s feet | 19 |
| Kakihana et al 37 | 51 (0:51) | Age (y): 65.5 (3.8) Height (m): 1.54 (0.06) Mass (kg): 55.4 (6.8) | K/L grade 1 (22) K/L grade 2 (24) K/L grade 3 (3) K/L grade 4 (2) | Age 50 years or greater; knee pain for at least 6 months; bilateral isolated knee OA with osteophyte presence in the medial tibiofemoral compartment; initial stiffness <30 min in the morning or crepitus on active motion of the knee | LWI | Neutral insole attached to participant’s feet | 20 |
| Kerrigan et al 38 | 15 (8:7) | Age (y): 69.7 (7.6) Height (m): 1.67 (0.07) Mass (kg): 83.9 (11.9) | K/L grade 3 (10) K/L grade 4 (5) | Knee pain on most days of a recent month; radiographic OA in that knee defined as an osteophyte; K/L grade 3 or greater; definite joint space narrowing in medial compartment but not in lateral compartment | LWI | Participant’s usual footwear with neutral insole | 22 |
| Kuroyanagi et al 39 | 21 (NA) | Age (y): 72 (NA) Height (m): 1.52 (0.04) Mass (kg): 50 (5) | K/L grade 2 (20 knees) K/L grade 3 (11 knees) K/L grade 4 (6 knees) | Age >50; medial compartment knee OA according to the ACRcriteria for diagnosis of knee OA; medial knee pain; radiographic osteophyte at the medial joint space and at least one of the following: bilateral isolated knee OA with osteophytes; initial stiffness <30 min in the morning or crepitus on active motion of the knee | LWI | Barefoot | 21 |
| Leitch et al 40 | 12 (5:7) | Age (y): 48 (9) Height (m): 1.72 (0.11) Mass (kg): 90.6 (16.8) BMI (kg/m2): 30.5 (4.2) | K/L grade 1 (2) K/L grade 2 (2) K/L grade 3 (3) K/L grade 4 (5) | Clinical diagnosis of OA confined to primarily the medial compartment | LWI | Standardised lab shoe | 19 |
| Maly et al 9 | 12 (9:3) | Age (y): 60.0 (9.4) Mass (kg): 99.2 (15.9) BMI (kg/m2): 32.4 (5.0) | K/L grade (NA) | Medial compartment knee OA confirmed by radiograph | LWI | Participant’s usual footwear | 19 |
| Moyer et al 41 | 16 (8:8) | Age (y): 55 (7.0) BMI (kg/m2): 32 (6.2) | K/L grade 1 (2) K/L grade 2 (5) K/L grade 3 (6) K/L grade 4 (3) | Varus alignment; symptomatic medial compartment knee OA; provided with prescription for a valgus knee brace; clinically and radiographically confirmed knee OA according to the Altman classification system; greater severity in the medial compartment of the tibiofemoral joint; pain localised to the medial side of the tibiofemoral joint; greater joint space narrowing on the medial side compared with the lateral | LWI | Standardised lab shoe | 19 |
| Pagani et al 42 | 10 (2:8) | Age (y): 57.5 (7.1) Height (m): 1.68 (0.04) Mass (kg): 78.8 (12.2) BMI (kg/m2): 28 (4.3) | K/L grade 2 (6) K/L grade 3 (4) | Age 50 years or greaterDiagnosis of knee OA K/L grade 2 or 3 | LWI | Standardised lab shoe | 19 |
| Shimada et al 43 | 23 (6:17) | Age (y): 67.0 (8.7) Height (m): 1.50 (0.07) Mass (kg): 60.3 (7.1) | K/L grade 1 (11 knees) K/L grade 2 (11 knees) K/L grade 3 (13 knees) K/L grade 4 (11 knees) | Bilateral medial compartment knee OA | LWI | Unspecified | 20 |
| Resende et al 44 | 20 (7:13) | Age (y): 67 (8.3) Height (cm): 170.0 (8.0) Mass (kg) 87.9 (18.0) | K/L grade 3 (20) | Radiographic medial knee OA; no history of falls; no injury or surgery on either lower limb in the last 6 months; no history of stroke or other form of arthritis; neuromuscular or cardiovascular disorders; able to ambulate without a gait aid; able to walk a city block and climb stairs in a reciprocal fashion | LWI | Neutral standardised lab sandal | 20 |
| Turpin et al 18 | 16 (6:10) | Age (y): 66.9 (12.5) Height (m): NA Mass (kg): NA BMI (kg/m2): 27.7 (7.3) | K/L grade 2 (10) K/L grade 3 (2) K/L grade 4 (4) | Radiographic evidence of medial compartment knee OA with K/L grade 2 or greater; varus malalignment; knee pain during walking that was >3/10 on most days of the previous month (on an 11-point scale) | SAI | Participant’s usual footwear | 20 |
| Yeh et al 45 | 15 (0:15) | Age (y): 66.8 (5.5) Height (m): 1.53 (0.04) Mass (kg): 57.4 (6.3) BMI (kg/m2): NA | K/L grade (NA) | Bilateral medial knee OA; both knees K/L grade 2 or 3; able to walk independently | LWAS | Standardised lab shoes | 21 |
*Methodological quality score is based on the modified Downs and Black Criteria,10 with a maximum score of 27.
ACR, American College of Rheumatology; BMI, body mass index; LWI, lateral wedge insoles; LWAS, lateral wedge insoles with arch support; KOOS, Knee injury and Osteoarthritis Outcome Score; MAS, medial arch support insoles; NA, not available; SAI, shock absorbing insoles; VAS, visual analogue scale; y, years.