Summary

The aim of the present article is to compare the maximal isometric strength of Hamstrings and Quadriceps in patients with knee osteoarthritis and healthy volunteers.

Abstract

Introduction

Knee osteoarthritis (KOA) affects the strength of both the flexion movement performed by hamstring muscles and the extension by quadriceps. Dynapenia is usually detected clinically by manual muscular testing, resulting in a subjective score such as the Lovett scale [1]. The word “dynapenia” is been used since 2008 [2] and increasingly thereafter to refer to a loss of strength (dyna=strength and penia=poverty, low content). This loss of strength is not necessarily associated to neurologic conditions [2]. In order to quantify dynapenia, clinicians can either use standard dynamometers for static measurements or new devices designed specifically for the purpose, such as DINABANG® [3][4] which includes power and torque measures.
Clinical observations of patients with knee osteoarthritis, who develop less strength [5], led us to formulate the hypothesis that the Lovett subjective scale could be further refined using a quantitative evaluation. To do so, we suggest doing a combination of dynamometer and flexo-extension angular measurements using a strength, torque and angular velocity measurement device called DINABANG [6]
The aim of the present article is to compare the maximal isometric strength of Hamstrings and Quadriceps in patients with knee osteoarthritis and healthy volunteers.

Materials And Methods

We measured the H and Q strength of 20 subjects, in both lower limbs, 12 Healthy Volunteers (HV) (age 64,9 ± 6,4 years, BMI 26,5 ± 3,5) and 8 KOA patients (KOAp) (63,4 ± 10,1 years, BMI 28,3 ± 3,7 with mild to moderate symptomatic unilateral primary knee osteoarthritis, according to Kellgren Lawrence II-III radiological classification. They all signed an informed consent as approved by the Ethics Committee (Number 2910-21 of 29 October 2021) of the “Hospital de Clínicas Dr Manuel Quintela”. To standardize all measurements, we used a specially designed chair called Chakadina [7] and DINABANG® to determine with three consecutive trials the maximum isometric strength of hamstring and quadriceps muscles, tending towards knee flexion and towards knee extension respectively at an angle of 60 degrees.

Results

Flexion strength was 190,5 ± 50,7 N for HV and 130,3 ± 37,5 N for KOAp. The loss of strength of KOAp compared to HV was 32 % in H force. Extension strength was 310 ± 120,8 N for HV and 190 ± 53,0 N for KOAp (. The loss of strength of KOAp compared to HV was 39 % in quadriceps force.

Discussion And Conclusion

KOA considerably diminishes the strength of both lower limb main movements: flexion and extension. Quadriceps loss appears somewhat more dramatic (39% loss) than Hamstring (32% lower). Generally, the rehabilitation team concentrates its efforts on recovering Q strength, neglecting the recovery of the H strength [6]. This modifies the H/Q strength ratio, which in turn alters the arthrokinematics of the knee, making it less stable during gait [5].
Several papers have described the loss of muscular strength in KOA patients due to the consequences of pain and other proprioceptive processes within the articulation and around it. Our results represent an attempt to quantify such loss, or dynapenia.

Key Words: Knee, Osteoarthritis, Strength, DINABANG®

REFERENCE
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