Evaluación del director por parte del supervisor escolar

Zaria is situated in the Guinea–Savannah belt of Northern Nigeria and has a population of 408,198 according to 2006 National population commission census figures. The climate of Zaria is subtropical and consists of a dry season from November to April and a wet season from May to October. Zaria is a cosmopolitan town and its high number of tertiary institution makes it a melting pot for all tribal groups. The dominant tribe in Zaria is Hausa. The occupation of the majority is trading, transportation and civil service work. Ahmadu Bello University Teaching Hospital is the main tertiary hospital in Kaduna and serves both the urban and rural dwellers of the state and by its nature also serves as a referral centre from other states.

42 3.3 STUDY POPULATION AND SIZE

The study population consisted of adult patients of both gender attending the rheumatology clinic. Patients with knee OA were selected for the study on the basis of the fulfillment of ACR clinical / radiographic criteria for knee osteoarthritis.⁽¹⁾ That is ,the presence of knee pain in addition to any one of the following features, namely: age > 50 years, stiffness of < 30minutes, presence of joint crepitus and presence of plain radiograph OA changes.

The inclusion / exclusion criteria used in the study is as shown in the table below.

Table 1 : showing the inclusion / exclusion criteria used in this study.

Inclusion Criteria Exclusion Criteria

Patient who fulfill the ACR knee OA criteria Patient with non traumatic knee pain Adult patients (age 20 and above) Willingness to participate in the study

Past history of knee trauma

Patients with concurrent hip arthritis Patients with inflammatory arthritis Previous knee arthroplasty

Congenital deformity of the lower limbs Symptomatic cardiac or renal disease

Symptomatic respiratory disease Refusal to grant consent

Those that had exclusion criteria were excluded from the study. In all, 20 subjects were excluded from the study. Of these, 4 patients had declined consent, 2 patients had previous stroke with residual hemiparesis, 4 patients had concurrent hip arthritis, 5

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patients had lumbosacral spondylosis and 4 subjects had past history of trauma to the knee from road vehicular accident. One patient was excluded as she had undergone bilateral knee arthroplasty.

SAMPLE SIZE DETERMINATION

The minimum sample size for the size for this study was 140 subjects, determined by

using Fischer’s statistical formular calculated as follows:  

2

2 1 )

d P P

n Z 



Where n= Minimum sample size

Z= Standard deviation (constant of 1.96, corresponding to 95% confidence interval) P= Prevalence of functional disability in knee OA subjects (90.2% in Nigerian study) d= Tolerable sampling error

Therefore, n = (1.96)² x 0.902x0.098 (0.05)² n=135

Allowing for 5% attrition rate/ concession for indeterminate results:

Adjusted sample size = 135 X 100 = 142.

95

3.4 METHODOLOGY

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One hundred and forty (140) consecutive consenting adult patients aged 20 years and above who met the ACR criteria for knee OA and do not fall into the exclusion criteria were enrolled into the study over a year period. A well structured interviewer administered questionnaire (see appendix 2) was filled containing details of the subjects’ biodata, history related to knee pain, duration of knee pain, knee stiffness and the presence of functional disability and the presence of comorbidity. The subjects had blood pressure and the following anthropometric measurements done thus:

Blood pressure measurement

Measurement of blood pressure in the subjects was done by auscultatory method, using Accuson sphygmomanometer with adult size cuff. The cuff was placed around the dominant upper arm at the same vertical height as the heart before inflation. Palpation method was used to get an estimate of the systolic blood pressure before auscultation.

The pressure at which the 1^st korotkoff sound was heard was taken as the systolic blood pressure, the point of disappearance of the 5^th korotkoff sound was taken as the diastolic blood pressure. Blood pressure was measured after a 5 minutes rest period by the patient and recorded to the nearest even number.

Weight Measurement

Weight of all subjects was measured using a platform weighing scale with the patient wearing light clothes and shoes off the feet. Weight was measured to the nearest 0.1 kg.

Height Measurement.

Height of the subjects was measured using a measuring rod (standometre) attached to a measuring platform. The standing height was measured as the maximum distance from the floor of the platform to the highest point on the head, with the subjects facing directly ahead, with their shoes off, feet together and arms by the side. Height measurement was done to the nearest 0.1 cm.

Body mass index (BMI) of the subjects was calculated using the formular- weight (kg)/

height² (m²). World Health classification of BMI was used to classify patients. BMI of

<18.5kg/m² =underweight, BMI 18.5 - 24.9kg/m² = normal weight, BMI 25-29.9 kg/m² = overweight, BMI 30-34.9 kg/m² = class 1 obesity, BMI 35-39.9 kg/m² = class 2 obesity, BMI >40kg/m²= class 3 obesity.

Waist circumference measurement

Waist circumference measurement was done using a 150cm non elastic plastic tape measure. The mid-point between the lower coastal margin and the iliac crest was used as landmark with the subjects standing, feet 25 cm apart. The tape measure was applied snugly without compressing any soft tissue. The waist circumference was measured to the nearest 0.1 cm, at the end of a normal expiration.

Hip circumference measurement

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Hip circumference was measured using a 150cm non elastic plastic tape measure. The tape was placed around the point of maximal gluteal circumference, with the subjects clothes removed except for light underwear, standing with the feets 15cm apart with weight equally distributed on each legs and the patient breathing normally.

Measurement was taken at the end of quiet expiration and done to the nearest 0.1 cm.

Patients were then examined thoroughly with special emphasis on the musculoskeletal system utilizing the standardized examination of the knee consisting of 10 items as done below.

Standardized knee examination

1. Palpation for joint crepitus: was done by placing the palm over the knee to feel for a