Knee flexor and extensor strength ratios with deficiency of the lateral collateral ligament

This investigation studied the peak torque and total work hamstring/quadriceps (HQ) ratios of 24 lateral collateral ligament (LCL) insufficient knees, and clarified the possible associations between different HQ ratios and the long-term outcomes of patients. Peak torque values were recorded at low (60 degrees/sec) and high (180 degrees/sec) speed of isokinetic movement, and the maximal isometric extension and flexion outputs were measured at the knee angle of 60 degrees from straight. Three standardized knee scoring scales were used to determine the subjective, functional, clinical, and radiologic outcomes of these LCL insufficient knees. In every test a great interpersonal variation of the HQ ratios was noticed, even in the healthy knees (range 24% to 154%). On the injured side the HQ ratios were in every test higher than on the healthy side, because of the weaker quadriceps muscle of the injured leg. In most cases, followup scores did not differ significantly between the groups with low (less than 50%), optimal (50% to 80%), or high (greater than 80%) HQ ratios of the LCL insufficient knees. However, in every test the scores were significantly (p less than 0.005 to 0.0001) better in the patients who had the HQ ratio of the injured knee near the uninjured side (less than 15%) compared with those with a clear difference (greater than 15%). These findings suggest that the HQ ratio is a very individual parameter, and therefore any general recommendation about the optimal value is very difficult to give. With regard to long-term outcome, the most ideal HQ ratio of an LCL insufficient knee seems to be the HQ ratio of the opposite, healthy extremity.