Investigation of standing balance in patients with diabetic neuropathy at different stages of foot complications

BACKGROUND

Diabetic peripheral neuropathy is known to cause postural instability. This study investigated standing balance in patients with diabetic neuropathy with secondary foot complications: foot ulceration, partial foot amputation and trans-tibial amputation, which are expected to pose further challenge to balance control.

METHODS

In this cross-sectional study, 23 patients with diabetic neuropathy alone (controls) were compared with 23 patients with diabetic foot ulceration, 16 patients with partial foot amputation and 22 patients with trans-tibial amputation. Posturography was used to determine the centre of pressure excursion during quiet standing. Differences between the 4 groups were tested using ANOVA and post-hoc comparisons.

FINDINGS

The 4 groups varied in neuropathy score (P=0.001) and demonstrated significant decline in balance from neuropathy alone to foot ulceration, to partial foot amputation and trans-tibial amputation based on total excursion of centre of pressure (P<0.001) and centre of pressure excursion in antero-posterior direction (P<0.001). The excursion of centre of pressure in medio-lateral direction varied between 4 groups (P<0.05) however, there was no significant trend. The distance between ankles increased significantly from neuropathy to trans-tibial amputee group (P=0.001). Post-hoc comparison with controls revealed that each of three study groups demonstrated decreased balance (diabetic neuropathy vs. foot ulceration, P=0.001, diabetic neuropathy vs. partial foot amputation, P=0.002 and diabetic neuropathy vs. trans-tibial amputation, P=0.009).

INTERPRETATION

Balance deterioration among patient groups from diabetic neuropathy alone to trans-tibial amputation appears to result from bio-mechanical impairment caused by progression of foot complications in addition to postural instability caused by diabetic neuropathy.

Walking performance in people with diabetic neuropathy: benefits and threats

AIMS/HYPOTHESIS

Walking is recommended as an adjunct therapy to diet and medication in diabetic patients, with the aim of improving physical fitness, glycaemic control and body weight reduction. Therefore we evaluated walking activity on the basis of capacity, performance and potential risk of plantar injury in the diabetic population before it can be prescribed safely.

SUBJECTS, MATERIALS AND METHODS

Twenty-three subjects with diabetic neuropathy (DMPN) were compared with 23 patients with current diabetic foot ulcers, 16 patients with partial foot amputations and 22 patients with trans-tibial amputations. The capacity for walking was measured using a total heart beat index (THBI). Gait velocity and average daily strides were measured to assess the performance of walking, and its impact on weight-bearing was studied using maximum peak pressure.

RESULTS

THBI increased (p<0.01) and gait velocity and daily stride count fell (p<0.001 for both) with progression of foot complications. The maximum peak pressures over the affected foot of patients with diabetic foot ulcers (p<0.05) and partial foot amputations (p<0.01) were higher than in the group with DMPN. On the contralateral side, the diabetic foot ulcer group showed higher maximum peak pressure over the total foot (p<0.05), and patients with partial foot amputations (p<0.01) and trans-tibial amputations (p<0.05) showed higher maximum peak pressure over the heel.

CONCLUSIONS/INTERPRETATION

Walking capacity and performance decrease with progression of foot complications. Although walking is recommended to improve fitness, it cannot be prescribed in isolation, considering the increased risk of plantar injury. For essential walking we therefore recommend the use of protective footwear. Walking exercise should be supplemented by partial or non-weight-bearing exercises to improve physical fitness in diabetic populations.

Risk of plantar ulceration in diabetic patients with single-leg amputation

BACKGROUND

There is a disconcerting rate of bilateral limb loss in patients with diabetes. Therefore, this study aimed to explore plantar loading of the surviving foot following unilateral trans-tibial amputation within a wider context of daily walking activity to investigate the precise risk to the surviving limb.

METHODS

Twenty-one subjects with diabetic neuropathy and trans-tibial amputation were matched for weight; height; age and gender with 21 control subjects with diabetic neuropathy without history of plantar ulceration. Gait parameters, in-shoe plantar pressure distribution and daily walking (using the step activity monitor) were recorded. Student's t-tests were used to compare groups (alpha-level: 0.05).

FINDINGS

The trans-tibial amputations group walked almost 30% slower compared to controls (P < 0.01), with reduced cadence (P < 0.01), and shorter strides (P < 0.01). Despite walking slower, the surviving foot showed higher mean peak plantar pressures in the trans-tibial amputations group over the heel (P < 0.001) however there was no significant difference over the I-II and lateral III-IV-V metatarso-phalangeal regions. Pressure time integral was higher over the heel (P < 0.00), I-II (P < 0.01) and III-IV-V metatarso-phalangeal (P < 0.05) in the trans-tibial amputations group. The amputee group walked less steps per day (P < 0.01).

INTERPRETATION

Adaptations in gait and level of walking activity affect plantar pressure distribution and ultimately the risk of ulceration to the surviving foot. Therefore rehabilitation measures should consider implications for plantar loading and the potential risk of ulceration to the surviving foot.