Apibantaweesakul S1,2,3, Limpisiri N2, Ditthapinan A2, Chernchujit B4, Kawakami Y5
1Waseda University, Graduate School of Sport Sciences, Saitama, Japan, 2Thammasat University, Faculty of Allied Health Sciences, Physical Therapy, Pathumthani, Thailand, 3Thammasat University, Faculty of Allied Health Sciences, Sports Science and Sports Development, Pathumthani, Thailand, 4Thammasat University, Faculty of Medicine, Orthopaedics, Pathumthani, Thailand, 5Waseda University, Faculty of Sport Sciences, Saitama, Japan
Background: Anterior cruciate ligament (ACL) injury is one of the most common knee injuries in sports. Consequences of the injury lead to deterioration of knee joint stability and motor performance, as well as changes of the knee muscle strength that could result in the loss of functional knee stability. Hamstrings and quadriceps strength ratio (H:Q ratio) is a clinical muscle balance assessment that is commonly used for identifying and monitoring rehabilitation in several injury conditions. However, the traditional H:Q ratio using the peak toques of hamstrings and quadriceps attained at different knee joint angles may limit its usefulness with respect to athletic performance. There is a need for assessing H:Q ratio at specific knee angles in evaluating ACL malfunction.
Purpose: To compare H:Q ratios at different angles of knee flexion (identical angles for the ratio determination) between healthy individuals and those with the ACL injury.
Methods: Fifteen male participants (5 complete ACL tear and 10 healthy participants) aged between 18-25 years participated in this study. Muscle strength was measured by using isokinetic dynamometer in conventional concentric strength-open kinetic chain contraction, at an angular velocity of 60°/s. Then H:Q ratios were computed at 15°, 30°, 45°, 60°, 75° and peak torque angles. The Mann-Whitney U test was used to compare the muscle strength and H:Q ratio at each knee flexion angle (plus the peak torque) between two groups.
Results: H:Q ratios at 15° and 30° of knee flexion in the ACL injury group was lower than the healthy group (Mean+SD: at 15°; 0.51+0.45 vs. 0.81+0.26, at 30°; 0.71+0.28 vs. 0.79+0.20, in ACL and healthy groups, respectively). H:Q ratios at other angles were similar between groups. In the ACL injury group, hamstrings muscle strength was lower than the healthy group at 15° and 30°, while quadriceps muscle strength was comparable to that of the healthy group. However, there were no significant difference in muscle strength or H:Q ratios at any angles or peak torques of knee flexion angle between ACL injury and healthy groups. In addition, the angle of peak torque in the ACL group tended to be more into knee flexion compared with the healthy group (Mean+SD = 51.80+15.74 and 39.00+5.93 degrees, in ACL and healthy groups, respectively, p=0.086).
Conclusion(s): The trend of H:Q ratios with the knee close to extension (15° and 30°) being lower in the ACL injury group, may represent the risk of re-injury or knee joint instability during exercises including walking, running, jumping and landing. It should be noted that the difference was not seen at more flexed knee joint angles, nor for the peak torque which has conventionally been adopted. The specific angle of muscle imbalance around the knee in ACL injury patients' points to the need for angle-specific strengthening of hamstrings muscles.
Implications: Specific isokinetic H:Q ratios should be included as a routine assessment of muscle strength balance around the knee in patients with ACL injury. Such an approach will contribute to further development of effective rehabilitation programs for the patients with ACL injury, and may lead to injury prevention.
Keywords: H:Q ratio, ACL injury, Isokinetic assessment
Funding acknowledgements: This study was supported by Department of Physical Therapy, Faculty of Allied Health Sciences, Thammasat University.
Purpose: To compare H:Q ratios at different angles of knee flexion (identical angles for the ratio determination) between healthy individuals and those with the ACL injury.
Methods: Fifteen male participants (5 complete ACL tear and 10 healthy participants) aged between 18-25 years participated in this study. Muscle strength was measured by using isokinetic dynamometer in conventional concentric strength-open kinetic chain contraction, at an angular velocity of 60°/s. Then H:Q ratios were computed at 15°, 30°, 45°, 60°, 75° and peak torque angles. The Mann-Whitney U test was used to compare the muscle strength and H:Q ratio at each knee flexion angle (plus the peak torque) between two groups.
Results: H:Q ratios at 15° and 30° of knee flexion in the ACL injury group was lower than the healthy group (Mean+SD: at 15°; 0.51+0.45 vs. 0.81+0.26, at 30°; 0.71+0.28 vs. 0.79+0.20, in ACL and healthy groups, respectively). H:Q ratios at other angles were similar between groups. In the ACL injury group, hamstrings muscle strength was lower than the healthy group at 15° and 30°, while quadriceps muscle strength was comparable to that of the healthy group. However, there were no significant difference in muscle strength or H:Q ratios at any angles or peak torques of knee flexion angle between ACL injury and healthy groups. In addition, the angle of peak torque in the ACL group tended to be more into knee flexion compared with the healthy group (Mean+SD = 51.80+15.74 and 39.00+5.93 degrees, in ACL and healthy groups, respectively, p=0.086).
Conclusion(s): The trend of H:Q ratios with the knee close to extension (15° and 30°) being lower in the ACL injury group, may represent the risk of re-injury or knee joint instability during exercises including walking, running, jumping and landing. It should be noted that the difference was not seen at more flexed knee joint angles, nor for the peak torque which has conventionally been adopted. The specific angle of muscle imbalance around the knee in ACL injury patients' points to the need for angle-specific strengthening of hamstrings muscles.
Implications: Specific isokinetic H:Q ratios should be included as a routine assessment of muscle strength balance around the knee in patients with ACL injury. Such an approach will contribute to further development of effective rehabilitation programs for the patients with ACL injury, and may lead to injury prevention.
Keywords: H:Q ratio, ACL injury, Isokinetic assessment
Funding acknowledgements: This study was supported by Department of Physical Therapy, Faculty of Allied Health Sciences, Thammasat University.
Topic: Musculoskeletal: lower limb; Sport & sports injuries; Disability & rehabilitation
Ethics approval required: Yes
Institution: Thammasat University
Ethics committee: Ethical Committee on Research Involving Human Subject
Ethics number: 083/2555
All authors, affiliations and abstracts have been published as submitted.
