Is hyperextension of the knee associated with imbalance of the hamstring/quadriceps ratio? A survey of musical theatre students

Elizabeth Sharp, MSc, MCSP, University College Hospital, London, UK; Curati, Giovanna BSc, MSCP; Alan Hakim, MA, FRCP, University College Hospital, London, UK; and Grahame Rodney, MD, FRCP, University College Hospital, London, UK

Purpose
Devan et al (1) showed that a sub-normal hamstring/quadriceps ratio associated with hyperextension of the knee predisposed to overuse knee injuries. Orchard et al (2) showed that a ratio < 61% predisposes to hamstring injury. We explored imbalance of this ratio in musical theatre students and whether this was linked with knee hyperextension, as hypermobility has been associated with injury in dancers (3).

Method

16 students with hyperextension of the knee and 16 without, age-sex matched took part in the study. Knee hyperextension was defined as extension greater than 10 degrees of normal range of motion.

Full knee extension was measured with a standard goniometer (4). Each student was also tested for generalised hypermobility according to the Beighton score (5). The torque of both hamstring and quadriceps muscles was measured on a KIN-COM isokinetic dynamometer. 

Results

Six individuals in each group had hamstring/quadriceps ratio <61%. Using non-parametric ttests no significant difference in hamstring/quadriceps ratio was found between the group with knee hyperextension and normals, nor was any association with found with higher Beighton scores. 

Conclusions

Hamstring/quads ratio is similarly spread between individuals with and without knee hyperextension or generalised hypermobility. It is unlikely to be an explanation for increased risk of injury in hypermobile dancers.

References

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J Rheumatol 2004 31(1):173-8

PMR Vol 4 No 1 1994: 2-7

J Rheumatol 2000 27(7):1777-9

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