Original Data

The Impact of Peripheral Artery Disease (PAD) on Lower Limb Kinematics in Type 2 Diabetes Mellitus

Claire Saliba Thorne, Erica Bartolo, Alfred Gatt, Cynthia Formosa

Manuscript submitted November 18, 2020; resubmitted January 4, 2021; accepted January 5, 2021.

Keywords: kinematics, lower limbs, biomechanics, diabetic foot, ankle joint, knee joint, peripheral artery disease

Abstract

BACKGROUND: Peripheral artery disease (PAD) and diabetes mellitus are factors known to influence gait characteristics. However, there is a lack of knowledge on the extent to which type 2 diabetes mellitus (T2D) and PAD as comorbidities cause limb and gait complications. AIM: The purpose of this study was to investigate the impact of PAD as a complication of T2D on ankle joint dorsiflexion and knee joint flexion angles using an optoelectronic motion analysis system and to find out whether these alterations are complications secondary to neuropathy or reduced blood perfusion. METHODS: Ninety participants were recruited in this quantitative study which applied a prospective, comparative, non-experimental approach. Participants with T2D and PAD (n = 60), categorized according to the severity of PAD (mild and severe group), were compared with a control group consisting of patients with T2D alone. An optoelectronic motion capture system was used to record mean maximum flexion angles of the knee joint and maximum mean dorsiflexion angles of the ankle joint during gait. RESULTS: 180 limbs were analyzed. Both mild and severe PAD participants exhibited a significant increase in mean maximum ankle joint dorsiflexion angles (p = 0.001) and a significant decrease in mean maximum flexion of the knee joint compared with the control subjects (p = 0.001). CONCLUSIONS: This study shows that T2D and PAD alter ankle joint and knee joint kinematics. This research provides biomechanical understanding of limb and gait alterations in this specific patient population which may contribute to an improved understanding of gait alterations and clinical management. The findings suggest that the reduction in ankle joint dorsiflexion commonly attributed to glycosylation in diabetes may be secondary to neuropathy and not to reduced blood perfusion.

Abbreviations: ABPI - ankle brachial pressure index; ANOVA - analysis of variance; EMG - electromyograph; HSD - honest significant difference; OA - osteoarthritis; RA - rheumatoid arthritis; PAD - peripheral artery disease; T2D - type 2 diabetes mellitus; TBPI - toe brachial pressure index; SPSS - Statistical Package of the Social Services

1. Introduction

Peripheral artery disease (PAD) is characterized by occlusion of the arteries of the lower extremities [1, 2]. Femoral, popliteal, tibial, and peroneal arteries are most commonly affected, leading to a higher risk of lower-extremity amputation [3, 4].

The risk of developing PAD is four times higher in the presence of diabetes mellitus than in its absence. Diabetes is rated as the strongest risk factor for the development of PAD [7-11], with a one percentage rise in HbA1c increasing the risk of developing PAD by 26% [5, 6]. Studies investigating the kinematics of people with PAD and type 2 diabetes mellitus (T2D) as separate morbidities report distinct gait variability, particularly in the ankle joint and knee joint [12]. Patients living with T2D alone tend to exhibit reduced ankle joint dorsiflexion and knee flexion during gait [13-16], particularly in the presence of peripheral neuropathy [17-18]. Apart from T2D, peripheral arterial disease alone was found to affect the ankle joint by increasing dorsiflexion during gait and to reduce knee joint flexion [19-22]. To date, there have been no studies investigating the effect of both PAD and T2D as co-morbidities on ankle joint dorsiflexion and knee flexion.

Altered biomechanical conditions brought about by both PAD and T2D may put this patient population at higher risk of developing deformities of the foot structure and muscle weakness, which in turn may result in higher predisposition to tissue stress [23], ulceration [24-26], falls, and even amputations [27]. Studies by Formosa et al. highlight the importance of meticulous and in-depth biomechanical examination with particular focus on joint movement and foot deformities [28, 29].

Many studies concentrated on the effect of diabetes on lower limb kinematics, but the impact of PAD is frequently disregarded [13-18]. It is plausible that the previously mentioned alteration in lower limb kinematics is secondary to nerve damage and muscle weakness resulting from long-standing ischemia. Muscle function is greatly dependent on vascular supply and the lack of it may alter the gait.

3D gait analysis may provide new insight into the mechanisms underlying altered biomechanics that may cause an increased risk of foot ulceration in patients with T2D and PAD. Thus, the purpose of this study was to investigate the impact of PAD as a complication of T2D on ankle joint dorsiflexion and knee joint flexion angles utilizing an optoelectronic motion analysis system.

References