Sometimes it is a little bit of a battle to convince our clients that we don’t necessarily need an MRI to prove or find out what is going on with their injury. MRI’s can provide too little or too much information. How can an MRI provide too much information?
Based around research, we know that up to 33% of the general public have a ‘bulging disc’ in their lower back. When someone then suffers acute pain it is not always due to this. However, if an MRI is then provided, this can be an easy solution to provide an answer to the patient that may be incorrect.
Patient history and clinical examination is the most important factor to the general assessment.
MRI does not add value over and above patient history and clinical examination in predicting time to return to sport after acute hamstring injuries: a prospective cohort of 180 male athletes, by Wangensteen, Almusa, Boukarroum, Farooq, Hamilton, Whiteley, and Tol, in British Journal of Sports Medicine (2015)
Hamstring strains are a common injury in many popular team sports and they lead to the loss of many hours of training and competition, as well as a very high re-injury rate. For a detailed introduction to hamstring strains, see the previous but one study review.
OBJECTIVE: To carry out a prospective observational trial to compare the predictive values of patient history and clinical examination vs. patient history, clinical examination plus magnetic resonance imaging (MRI) scans on determining the time to return to sport (as measured by number of days).
POPULATION:180 male athletes with a clinical diagnosis of acute hamstring injury, of whom 177 were professional athletes and 3 were competitive amateur athletes.
The researchers observed that 141 (78%) of the athletes displayed a positive MRI result while 39 (22%) displayed a negative MRI result. They noted that in 112 cases (79%) the primary injury occurred to the biceps femoris (long head). They found that the time to return to sport varied very widely from 1 – 72 days but the average was 21 ± 12 days.
Return to sport: without MRI
Excluding the MRI information, the researchers built a multiple regression model including only the variables from patient history and clinical examination. They found that two patient history variables (maximum recalled pain as registered on a visual analogue scale (VAS) and whether they were forced to stop sport within 5 minutes of the injury) were independently associated with return to sport time. However, the presence of previous injury was not associated with return to sport time. They also found that two clinical variables (length of hamstring tenderness along the muscle and presence of pain during resisted knee flexion at 90 degrees of hip and knee angle) were also independently associated with return to sport time. The total variance in return to sport time explained by these patient history and clinical examination was 29% (R-squared).
Return to sport: with MRI
Including the MRI information, the researchers built a second multiple regression model that included the variables from patient history, clinical examination and MRI. The total variance in return to sport time explained by these patient history, clinical examination and MRI variables was 32% (R-squared). Therefore, adding in the MRI variables explained just 3% of the variance in return to sport time.
What did the researchers conclude?
The researchers concluded that certain variables recorded during taking patient history and performing clinical examination at baseline can explain 29% of the variance in time to return to sport following an acute hamstring strain in male athletes. However, adding MRI has limited further benefit.
The study was limited as females were not included in the analysis. Different results might be observed in female athletes.