Study Design
This was a cross-sectional descriptive study which was carried out at the Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile Ife, Osun state, Southwest Nigeria. The duration of the study was between February 2015 and January 2016.
Subject selection
The study was carried out on adult subjects with type II diabetes mellitus who are between the ages of 40 and 80years. They were recruited from the diabetes clinic of the Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile Ife, Osun state.
The diabetic subjects included newly diagnosed diabetics, those who were still being worked up to achieve glycaemic control and diabetics who had been attending the clinic for a while and were stable. The control subjects were healthy volunteers from the general outpatient department, members of staff and patient relations who had no known history of diabetes mellitus and with fasting blood glucose less than 6.1mmol/l. A written informed consent was obtained from all the subjects in both groups.
Sampling Technique
Consecutive sampling method was used in the recruitment of the study participants. The study participants were consecutively included in the study until the desired number of study participants was obtained.
Sample size
The sample size for the study was determined using the Fisher formula90
31 z2pq
n = --- d2 Where:
n = sample size
z = standard normal deviation = 1.96 corresponding to 95% confidence interval p = prevalence = 4.7% = 0.04751
q = 1-p = 1-0.047 = 0.953
d = degree of accuracy desired = 0.05
Substituting these values into the formula yielded n = (1.96)2 x 0.047 x 0.953/ (0.05)2
n = 68.8
To allow for attrition of 10%, approximately 80 subjects with Type 2 DM were recruited for the study.
80 apparently healthy non diabetic subjects matched for age and sex were recruited as controls.
INCLUSION CRITERIA
This included all individuals that were 40 – 80 years old diagnosed with type 2 diabetes mellitus by the Endocrinologist. The healthy controls were age- and sex- matched apparently healthy adults between 40 and 80 years of age who had come fasting for at least 8 hours for other routine ultrasound scans and had Fasting blood glucose < 6.1mmol/l and with no known history of diabetes mellitus.
32 EXCLUSION CRITERIA
History of smoking
Age less than 40years and above 80years.
History of peripheral vascular, neurological (other than those of diabetic etiology), musculoskeletal or rheumatoid disease.
Any minor or major amputation involving the lower limbs
Charcot neuroarthropathy and hallux rigidus as a result of previous trauma.
Chronic use of steroids
Congenital ankle deformities.
Renal failure
Athletes and body builders.
EQUIPMENT AND MATERIALS These included:
- MINDRAY® Real time ultrasound machine: model DC-7 equipped with a 7.5-12.0 MHz high frequency linear array transducer.
- Ultrasound acoustic gel - Disposable gloves and wipes - Examination couch
- Stadiometer
- Weighing scale, model ZT-160, China.
-
10g Semmes Weinstein monofilament33 TECHNIQUE
The study group consisted of 80 diabetic patients and 80 age- and sex-matched controls.
A written informed consent was obtained from all participants.
The following general information were recorded: age and gender. Clinical history was obtained from subjects to know the duration of diagnosis of diabetes and history of any ulcers on the feet.
In the erect position, subjects had their weight (kg) and height (m) measured without shoes.
Their body weight was measured to the nearest 0.1 unit using a weighing scale while their height was measured to the nearest 0.1unit using a stadiometer (mechanical physician weighing scale attached with a height gauge, model ZT-160, China). Their BMI (kg/m2) was calculated by dividing their weight in kilograms by the square of their height in meters.
Physical examination was done for diabetic subjects and the presence or absence of PN was assessed using 10g Semmes Weinstein monofilament.
Venous blood was subsequently obtained in the morning following an overnight fast of at least 8 hours.
Fasting plasma glucose concentration was measured using spectrophotometer (a chemistry analyzer) and glycated haemoglobin was obtained by chromatography (using Siemens glycosylated haemoglobin machine) to assess for their level of glycemic control. Fasting blood glucose (FBG) was done for the control subjects while those with FBG of 6.1mmol/l or more or a known history of diabetes among the controls were excluded from the study.
Ultrasound evaluation of the AT and PF was subsequently done.
All ultrasonographic evaluation was performed in real time using the MINDRAY® Real time ultrasound machine: model DC-7equipped with a 7.5- 12.0 MHz high frequency linear array transducer.
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To examine the AT, the subjects were requested to lie down in a prone position on an examination couch with their feet extending beyond the edge of the couch.
Adequate exposure was ensured by rolling up the clothing to the knee level.
With the feet in neutral position, a layer of acoustic gel was applied over the area of the AT.
The 7.5–12 MHz linear array ultrasound transducer was placed on the coupling gel. The ultrasound probe was applied as perpendicular to the tendon as possible so as to prevent anisotropy. Depth and gain settings were adjusted to achieve acceptable images (Figs. 6&7).
Scanning of the tendon was done in longitudinal and transverse planes from the myotendinous junction of the AT to its insertion on the calcaneus. The thickness was measured on transverse plane at the level of the inferior portion of the medial malleolus (|Fig. 6). Both the right and left AT were evaluated and their thicknesses were measured at three consecutive times and the mean value for each side was obtained. Presence or absence of disorganization of the tendon fibers, hypoechoic foci and calcifications were also documented (Figs. 7-9).
Wipes were used to clean the gel off the examined area on completion of the examination.
To examine the PF, participants were positioned prone on the examination table with feet overhanging the edge and toes pointing away from the body. A layer of gel was applied over the region of the PF. A linear array high-resolution transducer (7.5- 12MHz) was placed over it and the PF was examined from its calcaneal insertion to the region of the forefoot under the metatarsophalangeal joints. The thickness of the fascia was measured on transverse plane over the centre of the arch at 2-3 cm from its calcaneal insertion (Fig. 10). This particular site was chosen as readings taken at this location are highly reproducible.
For each subject, three measurements each of the left and right plantar fascia were taken, and the mean plantar fascia thickness was calculated for each foot. Wipes were used to clean off the gel from the examined areas upon completion of the examination.
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Fig. 6: B-mode ultrasound image of the Achilles tendon (arrow), transverse view showing the measurement of a thickened Achilles tendon (between cursors).
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Fig. 7: B-mode ultrasound image of the Achilles tendon, longitudinal view showing disorganization of the Achilles tendon fibres (arrows).
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Fig. 8: B-mode ultrasound image of the Achilles tendon, longitudinal view showing the presence of hypoechoic foci (arrows) within the Achilles tendon fibres (arrows).
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Fig. 9: B-mode ultrasound image of the Achilles tendon, transverse view showing the presence of calcific focus (arrow) within the Achilles tendon fibres.
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Fig. 10: B-mode sonographic image of the plantar fascia, transverse view showing the measurement of a thickened plantar fascia (between cursors).
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