Age, sex and BMI-matched patients who had unilateral or bilateral arthritis of the knee with similar deformity and preoperative range of motion were enrolled for this prospective randomized controlled double blinded clinical trial. The study was approved by the institutional review board, and all patients provided written informed consent to participate in it. Inclusion criteria were patient of either sex who underwent primary unilateral or bilateral surgery or the first surgery of a staged bilateral total knee replacement where the second stage was at least 6 weeks later and those who were willing and able to return for follow-up over at least a six month postoperative period. Patients with preoperative haemoglobin less than 10g/dl and with bleeding disorder were excluded from the study. Two Groups were assigned: 1) APG group and 2) Control group.

Demographic data of the patient was recorded. All routine investigations were carried out and the results were noted. Preoperative haemoglobin, range of motion, WOMAC8 scores and KSS9 scores were noted. Standard knee radiographs i.e. weight bearing anteroposterior and lateral views in 30 degree flexion were taken. Patients were randomly allocated to platelet gel group and control group using opaque envelope method which was opened on the day of surgery.

Pain was measured daily using VAS scale which consisted of markings from 1 to 10. Number of tramadol injections given was also noted. Hemoglobin was measured on the day of surgery and postop day 3 by sysmex automated analyser. Postoperative blood loss was also noted by measuring the weight of soaked dressing and converting it into blood volume. Number of blood units transfused was also recorded. Post operative wound dressing was done on day 3 except in case of soakage. Wound was assessed using wound score form. Similar physiotherapy was advised for both the groups. All the patients were advised isometric quadriceps and ankle pumping exercises on postoperative day 0 (POD0). Patients with less pain did the exercises on POD0 only. They were advocated range of motion exercises and straight leg raising on POD1. Patients with decreased pain and who were comfortable were ambulated with help of a walker on POD2. Range of motion was recorded on day 5, 6 weeks and 12 weeks and 6 months postoperatively. WOMAC scores and KSS scores were noted as shown in outcome evaluation.

Statistical analysis The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows). All quantitative variables were estimated using measures of central location (mean, median) and measures of dispersion (standard deviation and standard error). Normality of data was checked by measures of skewness and Kolmogorov Smirnov tests of normality. For normally distributed data means were compared using student's t-test for two groups. For more than two groups ANOVA was applied. For Skewed data Mann-Whitney test was applied. Qualitative or categorical variables were described as frequencies and proportions. Proportions were compared using Chi square test. Sensitivity, specificity and diagnostic accuracy of different methods was calculated. All statistical tests were two-sided and were performed at a significance level of α=.05.