Table 3

Univariate results of the association between the clinical findings just after RTP and event of re-injuries

VariablenHR (95% CI)p Value
Patient characteristics
Categorical variables
 Previous hamstring injury2.9 (0.8 to 10.1)0.094
  No (reference)23
  Yes41
 Previous ipsilateral hamstring injury1.8 (0.7 to 5.0)0.233
  No (reference)30
  Yes34
 Previous hamstring injury within 12 months1.6 (0.6 to 4.3)0.309
  No (reference)45
  Yes19
 Previous ipsilateral hamstring injury within 12 months1.6 (0.6 to 4.2)0.388
  No (reference)47
  Yes17
 Level of sport2.5 (0.6 to 11)0.218
  Recreational (reference)15
  Competitive49
 Continuous variables
  Age1.00 (0.94 to 1.07)0.952
  Number of previous hamstring injuries1.26 (1.07 to 1.48)0.006
Injury characteristics
Categorical variables
 Sprinting injury type1.9 (0.5 to 6.5)0.321
  No (reference)17
  Yes47
 Injured muscle0.5 (0.1 to 3.4)0.440
  Biceps femoris (reference)56
  Semitendinosus/semimembranosus8
 MRI grade1.3 (0.4 to 4.1)0.624
  Grade I (reference)18
  Grade II46
 Continuous variables
  Time to RTP0.98 (0.94 to 1.01)0.126
  MRI hyperintensity volume1.00 (1.00 to 1.00)0.112
  MRI cross-sectional area (% of total muscle)0.95 (0.18 to 5.11)0.947
  MRI craniocaudal length1.00 (0.99 to 1.01)0.525
  MRI distance to tuber1.00 (0.98 to 1.00)0.978
Characteristics just after RTP
Categorical variables
 Subjective complete recovery0.5 (0.2 to 1.3)0.136
  Yes (reference)22
  No42
 Localised discomfort on palpation3.7 (1.4 to 9.6)0.008
  No (reference)48
  Yes16
 Active knee extension discomfort0.1 (0 to 303265.6)0.704
  No (reference)63
  Yes1
 Passive straight leg raise discomfort2.2 (0.3 to 16.7)0.445
  No (reference)62
  Yes2
 Discomfort on isometric knee flexion resistance in 15°3.7 (1.4 to 9.6)0.008
  No (reference)56
  Yes8
Continuous variables
 HaOS0.98 (0.95 to 1.01)0.198
 Active knee extension deficit1.10 (1.00 to 1.24)0.059
 Passive straight leg raise deficit0.95 (0.85 to 1.07)0.376
 Isometric knee flexion force deficit in 15°1.03 (1.00 to 1.06)0.074
  • HaOS, Hamstring Outcome Score; RTP, return to play.