Knee flexor/extensor strength ratio in follow-up of acute knee distortion injuries.

This study evaluated the peak torque and total work hamstring/quadriceps (HQ) ratios of 77 knees with a previous grade I distortion injury to find the possible relationship between different HQ ratios and long-term outcome. For measurement of quadriceps and hamstrings strengths, the CYBEX II isokinetic dynamometer was used. Peak torque values were recorded at low (60 degrees/sec) and high (180 degrees/sec) speeds of isokinetic movement, and the maximal isometric extension and flexion outputs were measured with the knee at a 60 degree angle. Three standardized knee scoring scales were used to determine the subjective, functional, clinical, and radiologic outcome of the injured knees. In every test, great intersubject variation of the HQ ratio was observed, even in healthy knees (range 19% to 148%). Follow-up scores of the groups with low (less than 50%), optimal (50% to 80%), or high (greater than 80%) HQ ratios of the injured knees did not differ significantly from each other. However, in every test the scores were significantly (p less than 0.001 to less than 0.0001) better in patients whose injured knee HQ ratio was nearly identical (less than or equal to 15%) rather than clearly different from (greater than 15%) the uninjured knee. These findings confirm our previous observation that the HQ ratio is an idiosyncratic parameter. Any general recommendation about optimal value is difficult to give. In evaluating long-term outcome, the most ideal HQ ratio of an injured knee seems to be the HQ ratio of the opposite, healthy extremity.