Can ultrasound measures of intrinsic foot muscles and plantar soft tissues predict future diabetes-related foot disease? A systematic review

Abstract

IntroductionDiabetes mellitus (DM) is associated with hyperglycaemia and advanced glycosylation end-products. In the foot, the consequences of chronic or uncontrolled diabetes are micro and macrovascular disease, neuropathy, reduced joint mobility and structural and soft tissue changes that increase the risk of ulcer development and amputation. Diabetes foot assessment currently includes a comprehensive history, neurological and vascular assessments and examination focussed on dermatological and musculoskeletal abnormalities. Whilst these assessments are helpful for predicting ulceration risk, direct identifiers that enable early therapeutic intervention are lacking. The intention of this review was to ascertain if B-mode ultrasound could be clinically applied to identify structural change in the diabetic foot and be utilised as an early predictor of ulceration risk.MethodsPrimary databases and grey literature sources were systematically searched. Selection criteria were that the study included a diabetic sample and used B-mode ultrasound to assess soft tissue structures of the foot (plantar skin, plantar fat pad or intrinsic muscles).ResultsFifteen studies were identified for inclusion (combined diabetic sample of 773). Ultrasound demonstrated reductions in tissue thickness in diabetics compared to non-diabetics under first (p = 0.01) and second (p = 0.03) metatarsal heads, but not the third (p = 0.24). Statistical heterogeneity was high for ultrasound thickness measures under metatarsal heads four/five (I2 65%, 81%) and very high for plantar skin (I2 98%), heel pad (I2 76%) and intrinsic muscles (I2 91%, 81%). Extensor digitorum brevis (EDB) ultrasound measures were significantly thinner in diabetics for all dimension measures compared to healthy controls except one study, which reported no significant differences in EDB thickness.ConclusionsNo direct evidence was found to indicate B-mode ultrasound measures can predict soft tissue changes in the plantar foot in diabetes, although low level studies indicate ultrasound has the potential to identify structural change. Clinical, methodological and statistical heterogeneity limit result applicability. This review highlights the need for robust prospective longitudinal research to examine the predictive validity of this method.

Reliability of ultrasound in evaluating the plantar skin and fat pad of the foot in the setting of diabetes

“…Measurements of plantar soft tissue thickness and assessments of plantar tissue characteristics demonstrating intra-observer reliability and agreement in this study may be useful to the diabetic population and clinicians who treat them. A number of studies have demonstrated that ultrasound measurements of the thickness of plantar soft tissues are different between people with and without diabetes, suggesting that such measurements may have a role in identifying causal or predictive changes in the feet of diabetics [ 25 ]. The measurements may also be useful in non-diabetic populations, such as those who have undergone foot reconstruction where localised high plantar pressure is suspected.…”

“…Ultrasound demonstrates this soft-tissue detail, and studies have suggested that ultrasound measurements of soft-tissue thickness [ 12 , 23 , 24 ] may have a role in assessing the risk of plantar foot ulceration in people with DM. However, the reliability of ultrasound measurements of the plantar skin and fat pad thickness are not well documented [ 25 ]. Ultrasound can also be used to depict tissue characteristics other than thickness, but such assessments are often overlooked, including those of the plantar foot in diabetic people, due to their perceived subjectivity [ 26 – 28 ].…”

Differences in the Sub-Metatarsal Fat Pad Atrophy Symptoms between Patients with Metatarsal Head Resection and Those without Metatarsal Head Resection: A Cross-Sectional Study

“…Secondly, seven patients with a history of metatarsal head resection should be excluded from the analysis due to the conduct of metatarsal head resection. However, the first metatarsal was evaluated in the entire sample; this is the most reliable area for reference measurement of the plantar soft tissues [23]. Analysis of the second metatarsal could be deleted from the study due to the possible risk of statistical errors caused by the loss of data.…”

“…A generous amount of ultrasound gel was placed between the skin and the transducer to avoid compressing the skin surface. The first and second metatarsals were measured to determine the plantar soft tissue thickness, as they are considered to be more reliable metatarsal areas and have lower statistical heterogeneity [23]. The ultrasound transducer was placed perpendicularly to the sesamoid bones and the second metatarsal head, and a longitudinal section of both the sub-metatarsal skin and the fat pad was obtained to measure the first and second metatarsal heads, respectively.…”

Diabetes and Its Cardiovascular Complications: Comprehensive Network and Systematic Analyses

“…An emerging method that could be more predictive include ultrasound measurement methods that, for example, can be used in plantar soft tissues in order to predict diabetic related changes in the foot ( 232 ). In one study, it was found that Sub-MTH fat pads were significantly thinner and subhalangeal fat pads were significantly thicker in diabetic neuropathic feet compared to neuropathic controls ( 233 ).…”