Alex Barwick

The relationship between foot motion and lumbopelvic–hip function: A review of the literature

Excessive pronation has been implicated in the development of numerous overuse injuries of the lower limb and is suggested to cause more proximal biomechanical dysfunction. Functional foot orthoses (FFO) are frequently prescribed for lower limb injury associated with excessive foot pronation and have been demonstrated to have efficacy with specific conditions. However, the mechanism of action of FFO is largely unknown. Research investigating the kinematic and kinetic changes associated with FFO use is inconclusive. Furthermore there is a growing body of evidence suggesting that changes to muscle activity patterns in response to FFO may be responsible for their therapeutic effect. Additionally, current research suggests dysfunction of musculature of the lumbopelvic-hip complex is involved in lower extremity functional changes and is related to the development some pathologies traditionally attributed to excessive foot pronation. Evidence of temporal coupling between the hip and the foot and changes in hip muscle activity associated with FFO use further suggest a relationship between proximal and distal lower limb function. The aim of this review is to discuss the association between foot and lumbopelvic-hip complex dysfunction and injury, assess the evidence for functional changes to lower limb and lumbopelvic-hip function with FFO use and finally to discuss the potential for changes to hip musculature activation with FFO use to influence distal mechanics and produce a therapeutic benefit.

Intra-tester and inter-tester reliability of post-occlusive reactive hyperaemia measurement at the hallux

BACKGROUND Post-occlusive reactive hyperaemia (PORH) is a measurement of the vasodilatory capacity of the microvasculature that is associated with cardiovascular disease, peripheral arterial disease and foot ulceration. The reliability of its measurement in the hallux (great toe) for clinical and research purposes has not been adequately assessed. This study assesses both the intra-tester reliability and inter-tester reliability of four methods of assessing PORH in the hallux. METHODS AND RESULTS A within-subject repeated measures design was used. Forty-two participants underwent PORH testing using four methods: pressure measurement with photoplethysmography; an automated laser Doppler technique with local heating; an automated laser Doppler technique without local heating; and a manual laser Doppler technique. Participants underwent testing on two occasions with a three to 14 day interval. Laser Doppler measurement with a heating probe was found to be the most reliable method of PORH measurement. The index of the area under the curve pre- and post-occlusion and peak perfusion as a percentage of baseline were the most reliable variables. CONCLUSIONS PORH can be reliably measured using laser Doppler when combined with a heating probe. Further research is required to determine the clinical utility of photoplethysmography in the measurement of PORH.

Peripheral sensory neuropathy is associated with altered postocclusive reactive hyperemia in the diabetic foot

Objective This study examined whether the presence of peripheral sensory neuropathy or cardiac autonomic deficits is associated with postocclusive reactive hyperemia (reflective of microvascular function) in the diabetic foot. Research design and methods 99 participants with type 2 diabetes were recruited into this cross-sectional study. The presence of peripheral sensory neuropathy was determined with standard clinical tests and cardiac autonomic function was assessed with heart rate variation testing. Postocclusive reactive hyperemia was measured with laser Doppler in the hallux. Multiple hierarchical regression was performed to examine relationships between neuropathy and the peak perfusion following occlusion and the time to reach this peak. Results Peripheral sensory neuropathy predicted 22% of the variance in time to peak following occlusion (p<0.05), being associated with a slower time to peak but was not associated with the magnitude of the peak. Heart rate variation was not associated with the postocclusive reactive hyperemia response. Conclusions This study found an association between the presence of peripheral sensory neuropathy in people with diabetes and altered microvascular reactivity in the lower limb.

Computed tomography derived bone density measurement in the diabetic foot

BackgroundThe accurate and reliable measurement of foot bone density is challenging and there is currently no gold standard technique. Such measurement is particularly valuable in populations at risk of foot bone pathology such as in those with long term diabetes. With research and development, computed tomography may prove to be a useful tool for this assessment. The aim of this study was to establish the reliability of a novel method of foot bone density measurement in people with diabetes using computed tomography.MethodsTen feet in people with diabetes were scanned with computed tomography twice with repositioning. Bone density (in Hounsfield units) was assessed in the trabecular and cortical bone in all tarsals and metatarsals. Reliability was assessed with intra-class correlation coefficients (95% confidence intervals), limits of agreement and standard error of measurement.ResultsThe reliability of the trabecular density of most bones was excellent with intra-class correlation coefficients ranging from 0.68 to 0.91. Additionally, cortical bone density showed fair to good reliability at the talus (0.52), calcaneus (0.59), navicular (0.70), cuboid (0.69), intermediate cuneiform (0.46) and first metatarsal (0.61).ConclusionsThe study established the reliability of a practical method of assessing the trabecular and cortical foot bone density using computed tomography scanning. This methodology may be useful in the investigation of foot bone disease occurring in diabetes and its early diagnosis, intervention and assessment of treatment efficacy. Further development of this method is warranted.

Diagnostic accuracy of the postexercise ankle–brachial index for detecting peripheral artery disease in suspected claudicants with and without diabetes:

The postexercise ankle–brachial index (ABI) is recommended in patients with normal resting ABI when peripheral artery disease (PAD) is suspected. The aims of this study were to determine the comparative diagnostic accuracy of the resting and postexercise ABI for detecting PAD, and, the effect of the presence of diabetes on these. Three methods of interpretation currently in use were also investigated: a reduction in postexercise ABI by >20% compared to resting ABI, an ABI value of ≤0.90 postexercise, or a reduction in systolic ankle pressure of >30 mmHg postexercise. This retrospective study used colour duplex ultrasound (CDU) as the reference standard. In 278 limbs (whole group), the resting ABI had an overall area under the curve (AUC) of 0.71, with the postexercise ABI yielding a similar diagnostic accuracy of AUC 0.72. In the non-diabetes group (n=171), the resting ABI had an overall AUC of 0.74 and the postexercise ABI had a similar AUC of 0.76. In the diabetes group (n=107), overall accuracy was reduced compared to the non-diabetes group, with the resting ABI having an overall AUC of 0.65 and the postexercise ABI yielding a similar accuracy with an AUC of 0.64. The overall diagnostic accuracy of the postexercise ABI for diagnosing PAD was not greatly improved compared to resting ABI. Given the lower overall diagnostic accuracy in the diabetes group, both the resting and the postexercise ABI results in diabetes populations should be interpreted with caution. There is a risk of undiagnosed disease if relying on these results alone to determine lower limb vascular status.

How sensitive and specific is continuous-wave Doppler for detecting peripheral arterial disease in people with and without diabetes? A cross-sectional study:

Background: Continuous-wave Doppler is frequently used for detecting peripheral arterial disease in patients with diabetes; however, there is limited evidence investigating diagnostic accuracy. This study aimed to determine sensitivity and specificity of continuous-wave Doppler for detecting peripheral arterial disease in populations with, and without, diabetes and to investigate the influence of disease severity on sensitivity of continuous-wave Doppler for detecting peripheral arterial disease. Results: Data from 396 participants were included. Using colour Duplex ultrasound as reference standard (N=66), printed continuous-wave Doppler waveform analysis sensitivity was 81.75% (95% confidence interval: 76.75 to 85.88) and specificity 89.34% (95% confidence interval: 82.62 to 93.67). Printed continuous-wave Doppler waveform analysis sensitivity for peripheral arterial disease was comparable to sensitivity calculated using angiography as the reference standard (81.67%; 95% confidence interval: 69.56 to 90.48). Sensitivity and specificity were unaffected by diabetes diagnosis (n = 176), sensitivity 82.76% (95% confidence interval: 74.86 to 88.55), and specificity 88.33% (95% confidence interval: 77.82 to 94.23). Conclusion: Continuous-wave Doppler is a fair assessment tool for peripheral arterial disease in a community-based sample with suspected peripheral arterial disease. Diagnostic accuracy of continuous-wave Doppler for peripheral arterial disease is unaffected by the presence of diabetes.

Post-occlusive reactive hyperaemia of skin microvasculature and foot complications in type 2 diabetes

AIMS Diabetes-related microvascular disease has been implicated in the development of foot ulceration and amputation. Assessment of microvascular function may be effective in identifying those at risk of diabetic foot complications. We investigated the relationship between active or previous foot complication and post-occlusive reactive hyperaemia (PORH) measured by laser-Doppler fluxmetry (LDF) in people with type 2 diabetes. METHODS PORH measures were obtained from the hallux apex in 105 people with type 2 diabetes. Associations were investigated between active or previous foot complication and PORH measures: time to peak (TtPeak) and peak as a percentage of baseline (P%BL). Multinomial logistic regression was used to determine the association of PORH with the likelihood of active foot ulcer or previous foot complication. RESULTS For each second increase in TtPeak, the likelihood of a participant having a history of foot complication is increased by 2% (OR=1.019, p=0.01). This association was not reflected in people with an active foot ulcer (OR=1.003, p=0.832). P%BL was not found to be significantly different between those with a current or previous foot complication and those without (p=0.404). CONCLUSIONS This investigation in a cohort with type 2 diabetes has demonstrated that longer TtPeak is associated with history of diabetic foot complications.

Foot bone density in diabetes may be unaffected by the presence of neuropathy

AIMS Neuropathies are common complications of diabetes and are proposed to influence peripheral bone, principally via an altered vascular supply. This study aimed to determine the relationship between subtypes of neuropathy and vascular reactivity on foot bone density in people with diabetes. METHODS A case-control observational design was utilised with two groups: those with diabetic peripheral large fibre neuropathy (n=23) and a control group with diabetes but without neuropathy (n=23). Bone density in 12 foot bones was determined with computed tomography scanning. Additionally, post-occlusive reactive hyperemia, presence of small fibre neuropathy and heart rate variability were determined. T-tests and hierarchical regression were used to examine the relationships among the variables. RESULTS No difference in foot bone density was found between those with and those without large fibre neuropathy. Furthermore, no association between heart rate variability or reactive hyperemia and bone density was found. Small fibre neuropathy was associated with increased cuboid trabecular bone density (p=0.006) with its presence predictive of 14% of the variance. CONCLUSIONS This study found no clear association between presence of diabetic neuropathies and foot bone density. Furthermore, vascular reactivity appears to have no impact on bone density.

Intra- and inter-tester reliability of post-occlusive reactive hyperaemia measurement at the hallux

Background Post-occlusive reactive hyperaemia (PORH) is a measurement of the vasodilatory capacity of the microvasculature that is associated with cardiovascular disease, peripheral arterial disease and foot ulceration. Reliability of its measurement in the toe for clinical and research purposes has not been adequately assessed. This study assesses both the intra and inter-tester reliability of four methods of assessing PORH in the toe.