Baseline assessment and their association with time to return to play in univariate analysis
| Baseline measure* | β-coefficient (95% CI) | p Value | Trend of prognosis of TTRTP | |
|---|---|---|---|---|
| Questionnaire | ||||
| Age, years | 29 (±7) | 0.14 (−0.44 to 0.73) | 0.622 | X |
| Intensity of sport | ||||
| <3 times per week (reference) | 15 (20%) | −7 (−18 to 3) | 0.177 | ↓ |
| ≥3 times per week | 59 (80%) | |||
| Level of sports | ||||
| Recreational (reference) | 19 (26%) | −8 (−17 to 2) | 0.099 | ↓ |
| Competitive | 55 (74%) | |||
| Mechanism of injury | ||||
| Stretching (reference) | 6 (8%) | −5 (−21 to 10) | 0.520 | X |
| No stretching | 68 (92%) | |||
| Mechanism of injury | ||||
| Sprinting (reference) | 54 (73%) | 4 (−5 to 14) | 0.379 | X |
| No sprinting | 20 (27%) | |||
| Previous hamstring injury | ||||
| No (reference) | 29 (39%) | −3 (−12 to 6) | 0.473 | X |
| Yes | 45 (61%) | |||
| Previous ipsilateral hamstring injury | ||||
| No (reference) | 36 (49%) | −1 (−9 to 8) | 0.901 | X |
| Yes | 38 (51%) | |||
| Hamstring injury within previous year | ||||
| No (reference) | 51 (69%) | 3 (−6 to 12) | 0.533 | X |
| Yes | 23 (31%) | |||
| Ipsilateral hamstring injury within previous year | ||||
| No (reference) | 54 (73%) | 2 (−7 to 12) | 0.632 | X |
| Yes | 20 (27%) | |||
| Previous ipsilateral hamstring ACL-graft harvesting | ||||
| No (reference) | 60 (81%) | −3 (−14 to 7) | 0.487 | X |
| Yes | 14 (19%) | |||
| Time to walk pain-free | ||||
| ≤1 day (reference) | 8 (11%) | 3 (−11 to 16) | 0.713 | X |
| >1 day | 66 (89%) | |||
| Self-predicted time to RTP indicated by the patient | 32 (±12) | 0.51 (0.16 to 0.86) | 0.005 | ↑ |
| Clinical examination | ||||
| Length of discomfort on palpation, cm | 11.9 (±6.8) | 0.60 (−0.01 to 1.21) | 0.053 | ↑ |
| Distance proximal border of discomfort area to ischial tuberosity, cm | 15.5 (±7.2) | −0.53 (−1.11 to 0.05) | 0.072 | ↓ |
| Distance maximal discomfort palpation to ischial tuberosity, cm | 19.8 (±6.8) | −0.36 (−1.01 to 0.28) | 0.265 | X |
| Pain on active knee extension test | ||||
| Negative (reference) | 14 (19%) | 0 (−10 to 11) | 0.934 | X |
| Positive | 60 (81%) | |||
| Active knee extension deficit, degrees | 11 (±13) | −0.02 (−0.30 to 0.34) | 0.914 | X |
| Pain on passive straight leg raise | ||||
| Negative (reference) | 37 (50%) | −2 (−11 to 6) | 0.574 | X |
| Positive | 37 (50%) | |||
| Passive straight leg raise deficit, degrees | 4 (±7) | 0.86 (0.29 to 1.42) | 0.003 | ↑ |
| Isometric knee flexion strength testing: pain score | 4.4 (±2.5) | 1.63 (−0.04 to 3.29) | 0.055 | ↑ |
| Isometric knee flexion strength testing: force deficit | 28 (±25) | 0.19 (0.03 to 0.36) | 0.025 | ↑ |
| MRI characteristics | ||||
| Grading | ||||
| Grade I (reference) | 19 (26%) | 3 (−7 to 13) | 0.544 | X |
| Grade II | 55 (74%) | |||
| Injured muscle | ||||
| Lateral/BF (reference) | 65 (88%) | −1 (−14 to 12) | 0.827 | X |
| Medial/ST or SM | 9 (12%) | |||
| Cross sectional area, % of total muscle | 37 (±28) | 0.05 (−0.11 to 0.20) | 0.545 | X |
| Longitudinal length, cm | 11.6 (±5.9) | −0.14 (−0.86 to 0.59) | 0.704 | X |
| Distance from tuber, cm | 15.2 (±7.8) | −0.58 (−1.2 to 0.06) | 0.075 | ↓ |
| Volume | 317 (±409) | 0.00 (−0.01 to 0.01) | 0.666 | X |
| Extramuscular fluid | ||||
| No (reference) | 14 (19%) | −1 (−12 to 10) | 0.899 | X |
| Yes | 60 (81%) | |||
Bold typeface: included for multivariate analysis (0.2).
*For continuous variables data is presented in mean (±SD) and for categorical variables the number (%) of athletes within each category.
ACL, anterior cruciate ligament; BF, biceps femoris; RTP, return to play; SM, semimembranosus; ST, semitendinosus; TTRTP, time to return to play; ↑, trending towards a longer time to RTP; ↓, trending towards a shorter time to RRP; X, not associated with a trend in time to RTP (p>0.2).