Contact Cast Versus Posterior Slab as Offloading Modality for Charcot Neuroarthropathy of Foot in Diabetes (OFFLOAD Study): A Multicentric, Non-inferiority Study

Background:

The etiopathogenesis of Charcot neuroarthropathy (CN) is intriguing since its early description in 1868. Early elucidation for the causation of CN with the neurotraumatic and neurovascular theories were accurate in their times. Of late, the conceptual understanding of CN has evolved after description of the role of osteoclastic resorption of foot bones by activation of receptor activator of nuclear factor kappa-B (RANK). The activation of RANK by RANK ligand (RANKL) occurs as a result of recurrent trauma to an insensate foot inciting a pro-inflammatory cascade of multiple inflammatory cytokines locally, the most common being tumour necrosis factor-α (TNF-α), interleukin-1ß (IL-1β) and interleukin-6 resulting in a local 'cytokine storm'. In addition, non-inflammatory factors including hyperglycemic milieu by increasing advanced glycosylation end products (AGEs), and autonomic neuropathy by causing a decrease in calcitonin gene-related peptide (CGRP) and endothelial nitric oxide synthase, can upregulate the RANKL/ NF-кB pathway.

Active CN of foot is defined clinically as a localised swelling, erythema and temperature difference exceeding 2˚C compared to a similar site on the opposite foot. The knee high non-removable total contact cast (TCC) is preferred as the treatment for the management of active CN.

Problem Statement: TCC has inherent limitations including worsening of bone mineral density (BMD), cast-related tissue injury, shin ulcers and prolonged immobilization usually for 6 to 12 months) and adversely impact the quality of life of individuals with CNO. Moreover, TCC is associated with sweating, maceration, in-TCC skin ulceration and intolerance in hot weather of tropical countries.

A knee-high walker rendered non-removable is suggested as a second choice in order to immobilise and offload the foot as a conditional recommendation with low quality of evidence. Presently there are no randomized controlled head-to head comparison of these non-removable knee high devices for active CNO.