Univariate analysis: baseline characteristics of patient history and clinical examination findings and their associations with time to RTS
| All cases | MRI-positive cases | MRI-negative cases | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Variable | N | Baseline measures | Mean RTS | β-Coefficient (95% CI) | N | Baseline measures | Mean RTS | β-Coefficient (95% CI) | N | Baseline measures | Mean RTS | β-Coefficient (95% CI) |
| Patient history | ||||||||||||
| Age (years) | 180 | 26 (±5) | – | −0.2 (−0.5 to 0.1) | 141 | 26 (±5) | – | −0.3 (−0.7 to 0.1) | 39 | 25 (±5) | – | −0.2 (−0.8 to 0.3) |
| Height (cm) | 180 | 177 (±8) | – | −0.1 (−0.3 to 0.1) | 141 | 177 (±7) | – | 0.01 (−0.3 to 0.3) | 39 | 179 (±10) | – | −0.1 (−0.4 to 0.2) |
| Weight (kg) | 180 | 75 (±12) | – | −0.04 (−0.2 to 0.1) | 141 | 75 (±12) | – | 0.01 (−0.2 to 0.2) | 39 | 76 (±11) | – | −0.10 (−0.4 to 0.1) |
| Maximum pain score (VAS 0–10) | 179 | 6.2 (±1.9) | – | 2.6 (1.7 to 3.4) | 140 | 6.5 (±1.9) | – | 2.3 (1.4 to 3.3) | 39 | 4.9 (±1.5) | – | 0.2 (−1.5 to 1.9) |
| Sport | 180 | 3.5 (−0.6 to 7.6) | 141 | 5.3 (0.7 to 9.8) | 39 | −0.5 (−6.4 to 5.4) | ||||||
| Non-football | 41 (23) | 24 (±13) | 31 (22) | 27 (±10) | 10 (26) | 12 (±8) | ||||||
| Football* | 139 (77) | 21 (±11) | 110 (78) | 23 (±11) | 29 (74) | 13 (±8) | ||||||
| Sprinting vs non-sprinting | 180 | 3.2 (−0.3 to 6.8) | 141 | 3.5 (−0.4 to 7.4) | 39 | 1.5 (−3.7 to 6.8) | ||||||
| Sprinting | 109 (61) | 23 (±12) | 86 (61) | 25 (±12) | 23 (59) | 13 (±8) | ||||||
| Non-sprinting* | 71 (39) | 20 (±10) | 141 | 55 (39) | 22 (±10) | 16 (41) | 12 (±9) | |||||
| Injury occurred | 177 | 1.1 (−2.6 to 4.7) | 140 | 0.8 (−3.2 to 4.8) | 37 | 1.2 (−4.3 to 6.7) | ||||||
| Game | 109 (62) | 22 (±12) | 87 (62) | 24 (±12) | 22 (59.5) | 13 (±9) | ||||||
| Training* | 68 (38) | 21 (±12) | 53 (38) | 23 (±12) | 15 (40.5) | 12 (±5) | ||||||
| Forced to stop within 5 min | 178 | 7.3 (3.5 to 11.2) | 139 | 5.4 (0.8 to 10.1) | 39 | 5.4 (0.5 to 10.3) | ||||||
| Yes | 131 (74) | 23 (±12) | 109 (78) | 25 (±12) | 22 (56) | 15 (±9) | ||||||
| No* | 47 (26) | 16 (±10) | 30 (22) | 20 (±11) | 17 (44) | 10 (±5) | ||||||
| Previous hamstring injury | 178 | 0.5 (−3.0 to 4.0) | 140 | 2.4 (−1.4 to 6.4) | 38 | −4.1 (−9.2 to 1.1) | ||||||
| Yes | 82 (46) | 21 (±11) | 62 (44) | 25 (±11) | 20 (53) | 11 (±6) | ||||||
| No* | 96 (54) | 22 (±13) | 78 (56) | 23 (±11) | 18 (47) | 15 (±9) | ||||||
| Previous low back pain | 174 | 0.3 (−4.2 to 4.7) | 136 | 1.2 (−3.7 to 6.1) | 38 | −4.5 (−11.5 to 2.6) | ||||||
| Yes | 30 (17) | 21 (±12) | 24 (18) | 24 (±7) | 6 (16) | 9 (±6) | ||||||
| No* | 144 (83) | 21 (±9) | 112 (82) | 23 (±12) | 32 (84) | 14 (±8) | ||||||
| Clinical examinations | ||||||||||||
| Length of hamstring tenderness (cm) | 180 | 6.6 (±3.8) | – | 1.0 (0.5 to 1.4) | 141 | 7.0 (±3.8) | – | 0.9 (0.4 to 1.4) | 39 | 5.2 (±3.5) | – | 0.1 (−0.7 to 0.9) |
| Width of hamstring tenderness (cm) | 180 | 3.8 (±2.4) | – | 1.2 (0.5 to 1.9) | 141 | 3.9 (±2.4) | – | 1.2 (0.4 to 2.0) | 39 | 3.2 (±2.1) | – | −0.2 (−1.5 to 1.0) |
| Pain on trunk flexion | 180 | 9.1 (5.1 to 13.0) | 141 | 5.7 (0.6 to 10.9) | 39 | 8.4 (3.9 to 12.8) | ||||||
| Yes | 140 (78) | 23 (±12) | 118 (84) | 25 (±12) | 22 (56) | 16 (±8) | ||||||
| No* | 40 (22) | 14 (±8) | 23 (16) | 19 (±8) | 17 (44) | 8 (±4) | ||||||
| Pain with active knee flexion | 173 | 5.2 (1.8 to 8.7) | 134 | 4.0 (0.1 to 7.9) | 39 | 4.3 (−1.1 to 9.7) | ||||||
| Yes | 74 (43) | 24 (±13) | 62 (46) | 26 (±13) | 12 (31) | 16 (±11) | ||||||
| No* | 99 (57) | 19 (±10) | 72 (54) | 22 (±10) | 27 (69) | 11 (±6) | ||||||
| Painful passive straight leg raise | 180 | 6.1 (1.8 to 10.4) | 141 | 3.6 (1.7 to 9.0) | 39 | 3.9 (−1.4 to 9.1) | ||||||
| Yes | 145 (81) | 23 (±12) | 120 (85) | 24 (±12) | 25 (64) | 14 (±9) | ||||||
| No* | 35 (19) | 17 (±9) | 21 (15) | 21 (±9) | 14 (36) | 10 (±6) | ||||||
| Painful active knee extension | 180 | 7.2 (3.3 to 11.2) | 141 | 6.4 (1.6 to 11.3) | 39 | 2.8 (−2.5 to 8.0) | ||||||
| Yes | 139 (77) | 23 (±12) | 115 (82) | 25 (±12) | 24 (61.5) | 14 (±9) | ||||||
| No* | 41 (23) | 16 (±9) | 26 (18) | 19 (±9) | 15 (38.5) | 11 (±6) | ||||||
| Painful resisted knee flexion 90° | 180 | 8.1 (2.9 to 13.3) | 141 | 6.2 (−0.4 to 12.8) | 39 | 5.3 (−0.6 to 11.2) | ||||||
| Yes | 158 (88) | 22 (±12) | 128 (91) | 24 (±12) | 30 (77) | 14 (±8) | ||||||
| No* | 22 (12) | 14 (±9) | 13 (9) | 18 (±8) | 9 (23) | 9 (±6) | ||||||
| Painful resisted knee flexion 30° | 180 | 6.9 (2.2 to 11.7) | 141 | 6.1 (0.4 to 11.8) | 39 | 4.0 (−2 to 10.0) | ||||||
| Yes | 153 (85) | 22 (±12) | 123 (87) | 25 (±11) | 30 (77) | 14 (±8) | ||||||
| No* | 27 (15) | 16 (±9) | 18 (13) | 19 (±9) | 9 (23) | 10 (±5) | ||||||
| Active slump | 177 | 3.2 (−0.9 to 7.2) | 140 | 4.2 (−0.3 to 8.6) | 37 | −2.6 (−9.0 to 3.9) | ||||||
| Positive | 43 (24) | 24 (±11) | 35 (25) | 27 (±14) | 8 (22) | 11 (±6) | ||||||
| Negative* | 134 (76) | 21 (±13) | 105 (75) | 23 (±10) | 29 (78) | 14 (±8) | ||||||
Data are presented as the mean time to RTS within each group (±SD). For categorical data, the distribution of cases within each group is presented (valid percentage). Regression coefficients are presented as unadjusted unstandardised β-coefficients with 95% CIs, representing the increase in time to RTS per 1 unit change.
*Reference category. Statistical significant (p≤0.05) associations are presented in bold and italics.
RTS, return to sport; VAS, visual analogue scale.