Evaluating the effect of apex position and rocker in curved rocker shoes

Abstract

BackgroundCurved rocker shoes are designed with a contoured outsole which can be characteristics by three principle design features: rocker angle, apex angle and apex position. Although these shoes are routinely prescribed to reduce in-shoe pressure in patients with diabetes, there is only minimal scientific evidence to inform the choice of value for each of the three design features. Results from a previous study [1], suggested that a 95°apex angle may be the best compromise for offloading the different regions of the forefoot. The results of this study also suggested that higher rocker angle may lead to decrease pressure, however, this study did not quantify the precise effect of rocker angle and apex position in shoes with a 95°apex angle.

Plantar pressure thresholds as a strategy to prevent diabetic foot ulcers: A systematic review

“…Most studies were conducted from 2008 to 2022, only one study [ 30 ] is older, conducted in 1998. Twenty-two studies [ 25 , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [49] , [50] , [51] ] focus on reducing plantar pressure by applying pressure thresholds on the foot solely inside the shoe. One study [ 30 ] presents only pressure thresholds for the barefoot foot with emphasis on identifying regions of interest in the foot or classifying risk groups.…”

“… Footwear modified in the area where an average peak pressure ≥200 kPa occurs, in 12 steps/foot. Chapman , 2014 [ 38 ] Reduce plantar pressure through balance shoes and orthotics. 87 (−/−); --- – 1 session Plantar region.…”

In-shoe pressure thresholds for people with diabetes and neuropathy at risk of ulceration: A systematic review

“…The evidence of the effectiveness of these in-shoe pressure threshold is limited to just four studies [34,37,41,48], consisting of two non-RCT cohort studies [41,48] and one RCT [34] relating to the 200 kPa threshold and one RCT relating to the 35 mmHG threshold [37]. The majority of these studies are non-RCT (n=17) [22,33,35,36,[38][39][40][41][42][43][44][45][46][48][49][50][51] concerned with the feasibility of various mechanisms of pressure reduction within the threshold target or as a benchmark for evaluating multiple interventions e.g. rival insoles or footwear designs.…”

“…of steps in Table 2). This 200 kPa threshold was used primarily as a benchmark in the design and modification of footwear (n=9) [34,35,39,[40][41][42][43][44]50], insoles (n=3) [36,45,46] and orthoses (n=1) [47] but also in the analysis of equinus (n=1) [22] and real-time modification of gait to reduce pressure ("biofeedback") (n=2) [34,51]. One study was unique in using a 450 kPa barefoot pressure threshold in the initial selection of regions of interest for optimised insole designs later assessed using the 200 kPa threshold [46].…”

“…Both the 200 kPa and 35 mmHG in-shoe pressure thresholds have been applied to prevent reulceration in those with diabetes, neuropathy and a history of ulceration (n=11) [34, 36, 37, 39-44, 47, 48]. The 200 kPa threshold was originally intended to prevent re-ulceration, but has since been applied to those with diabetes, neuropathy and no history of ulceration (n=2) [35,45] or mixed groups of both (n=3) [36,44,47] , or with diabetes without neuropathy (n=2) [35,50]. Most studies aim to prevent re-ulceration in those with a "recently healed ulcer" (n=8) [34, 37, 41-44, 39-40, 48] meaning an ulcer that healed within the 18 months prior to the study (n=6) [34, 42-43, 39-40, 48] or which has been healed for more than 90 days (n=1) with a mean of 3.6 years [41] or where the length of time since the ulcer healed is unspecified (n=2) [44,37].…”