Huang C1, Fu SN1, Li Z1, Yeung SS2, Chan PK3
1The Hong Kong Polytechnic University, Department of Rehabilitation Sciences, Hong Kong, Hong Kong, 2Maclehose Medical Rehabilitation Centre, Physiotherapy Department, Hong Kong, Hong Kong, 3Queen Mary Hospital, Department of Orthopaedic and Traumatology, Hong Kong, Hong Kong
Background: Knee osteoarthritis (KOA) is one of the most common diseases leading to disability in the senior population. Muscle weakness and stiffness are two major components of joint pain and dysfunction. Flexibility of the quadriceps is found lower in people with KOA than the healthy older, and is correlated with intensity of pain. How muscle stiffness and joint loading links during gait has not been explored. Such information is essential to prevention and rehabilitation of this common disease.
Purpose: This study aims to explore possible relationship between passive tension of the three superficial muscle heads of quadriceps femoris and knee joint loading estimated from gait analysis.
Methods: Symptomatic patients with medial compartment OA were recruited from a regional rehabilitation center of Hong Kong. Passive muscle stiffness of vastus lateralis (VL), rectus femoris (RF) and vastus medialis obliquus (VMO) were measured by Supersonic shear-wave elastography in Young's modulus. Knee joint was supported in 60° flexion. Joint loading was measured by an eight-camera Vicon system. Each patient had to finish at least 5 trials unshod in self-selected speed. Knee external adduction moment (KAM) 1st peak and impulse were calculated. Partial correlation between passive tension and KAMs was assessed by Spearman's rho test with all and subgroup of Kellgren-Lawrence (KL) grade, when controlling for gender, walking speed, pain level and confounding lower limb problem.
Results: Fifty-four eligible patients were included in the study (Female/male: 43/11; Age: 62.4±5.8years; BMI: 26.2±3.7kg/m2; KL1/2/3: 6/28/20; Bilateral/Unilateral: 49/5). Young's modulus was 5.8±1.8, 10.9±5.0 and 4.4±1.0 KPa for VL, RF and VMO respectively. The magnitude of KAM 1st peak was 5.1±2.0 Nm/BW*HT% and KAM impulse was 2.0±0.8 Nm.s/BW*HT%. When analysis was conducted on all patients, no significant correlation was detected between muscle Young´s modulus and KAMs. However, in patients of KL grade 2, KAM 1st peak of the more affected knee was significantly related to Young's modulus of ipsilateral RF (rho=0.41, p=0.04) and contralateral VMO (rho=0.51, p=0.01). KAM impulse was significantly associated with Young's modulus of RF in ipsilateral side (rho=0.49, p=0.02); it was also related to Young's modulus of VMO (rho=0.50, p=0.01) and VL (rho=0.45, p=0.03) in contralateral side. No such correlation could be found in patients of KL grade 3.
Conclusion(s): The findings of this study indicate that higher passive stiffness of superficial heads of quadriceps femoris is associated with larger joint loading in patients with medial KOA. Such association could only be revealed in patients with mild OA, suggesting the contribution of skeletal muscles to mechanical loading in an earlier stage of KOA. Besides, there also existed a cross-limb relationship between muscle stiffness and KAMs, indicating the specific role of different muscle heads and bilateral influence of quadriceps to control knee joint motion.
Implications: Passive stiffness of quadriceps femoris is likely involved in knee joint loading transition in patients with mild KOA. In the management of these patients, attention could be paid on the enhancement of inter-limb balance of quadriceps stiffness.
Keywords: Muscle stiffness, Joint loading, Medial knee osteoarthritis
Funding acknowledgements: Sincere thanks to Dr and Mrs Lui Che Woo for donation of Supersonic ultrasound shear-wave elastography machine.
Purpose: This study aims to explore possible relationship between passive tension of the three superficial muscle heads of quadriceps femoris and knee joint loading estimated from gait analysis.
Methods: Symptomatic patients with medial compartment OA were recruited from a regional rehabilitation center of Hong Kong. Passive muscle stiffness of vastus lateralis (VL), rectus femoris (RF) and vastus medialis obliquus (VMO) were measured by Supersonic shear-wave elastography in Young's modulus. Knee joint was supported in 60° flexion. Joint loading was measured by an eight-camera Vicon system. Each patient had to finish at least 5 trials unshod in self-selected speed. Knee external adduction moment (KAM) 1st peak and impulse were calculated. Partial correlation between passive tension and KAMs was assessed by Spearman's rho test with all and subgroup of Kellgren-Lawrence (KL) grade, when controlling for gender, walking speed, pain level and confounding lower limb problem.
Results: Fifty-four eligible patients were included in the study (Female/male: 43/11; Age: 62.4±5.8years; BMI: 26.2±3.7kg/m2; KL1/2/3: 6/28/20; Bilateral/Unilateral: 49/5). Young's modulus was 5.8±1.8, 10.9±5.0 and 4.4±1.0 KPa for VL, RF and VMO respectively. The magnitude of KAM 1st peak was 5.1±2.0 Nm/BW*HT% and KAM impulse was 2.0±0.8 Nm.s/BW*HT%. When analysis was conducted on all patients, no significant correlation was detected between muscle Young´s modulus and KAMs. However, in patients of KL grade 2, KAM 1st peak of the more affected knee was significantly related to Young's modulus of ipsilateral RF (rho=0.41, p=0.04) and contralateral VMO (rho=0.51, p=0.01). KAM impulse was significantly associated with Young's modulus of RF in ipsilateral side (rho=0.49, p=0.02); it was also related to Young's modulus of VMO (rho=0.50, p=0.01) and VL (rho=0.45, p=0.03) in contralateral side. No such correlation could be found in patients of KL grade 3.
Conclusion(s): The findings of this study indicate that higher passive stiffness of superficial heads of quadriceps femoris is associated with larger joint loading in patients with medial KOA. Such association could only be revealed in patients with mild OA, suggesting the contribution of skeletal muscles to mechanical loading in an earlier stage of KOA. Besides, there also existed a cross-limb relationship between muscle stiffness and KAMs, indicating the specific role of different muscle heads and bilateral influence of quadriceps to control knee joint motion.
Implications: Passive stiffness of quadriceps femoris is likely involved in knee joint loading transition in patients with mild KOA. In the management of these patients, attention could be paid on the enhancement of inter-limb balance of quadriceps stiffness.
Keywords: Muscle stiffness, Joint loading, Medial knee osteoarthritis
Funding acknowledgements: Sincere thanks to Dr and Mrs Lui Che Woo for donation of Supersonic ultrasound shear-wave elastography machine.
Topic: Musculoskeletal; Musculoskeletal: lower limb; Older people
Ethics approval required: Yes
Institution: The Hong Kong Polytechnic University
Ethics committee: Human Subjects Ethics Subcommittee of the Departmental Research Committee
Ethics number: HSEARS20170406003
All authors, affiliations and abstracts have been published as submitted.
