Effects of modified drainage on total knee arthroplasty

INTERVENTION: Participants are randomly allocated to one of three groups. Three groups all underwent general anaesthesia. The same surgeon performed the procedure. Mean arterial pressure of 60 to 70 mmHg and femoral nerve block with a catheter was maintained for postoperative pain management. The tourniquet was inflated to 100 to 120 mmHg. All drainage bottles were Drainobag® 600 (B. Braun Medical Inc., Melsungen, Germany). Group A: traditional drainage, negative pressure drainage 4 hours after the operation of total knee replacement. Group B: modified drainage, normal (atmospheric) pressure drainage for 12 hours, negative pressure drainage achieved by by pumping 500 ml air out of the drainage bottle for 12 hours. Group C: No drainage. Knee range of movement (ROM), including isometric quadriceps and straight leg raise exercises, were encouraged if the pain was tolerable. Passive movement with a continuous passive motion machine was encouraged on the second postoperative day.The follow up was 90 days post‐operation. CONDITION: Total knee replacement for osteoarthritis ; Musculoskeletal Diseases PRIMARY OUTCOME: Blood loss determined using haemoglobin levels before surgery and 1, 2 and 3 days after surgery.; Blood volume (BV) was estimated according to the method of Nadler et al. taking sex, body mass index, and height into account. For males BV = (0.3669 x height3 ) + (0.03219 x weight) + 0.6041 and for females BV = (0.3561 x height3 )+ (0.03308 x weight) + 0.1833.; Total blood loss is calculated from total hemoglobin loss (Hbloss), which in turn is calculated from the difference between preoperative Hb and the minimum Hb during the hospital stay (postoperative day 2 in our case): Blood loss (in mL) = 100 mL/dL x Hbloss/Hbi; Hbloss = BV x (Hbi – Hbe) x 10 dL/L + Hbt; Hbi = Hb concentration before surgery (g/dL); Hbe = Hb concentration during hospital stay (g/dL); Hbt = Total amount of allogeneic Hb transfused (g).; Because there were no transfusions, this variable was dropped from the equation in our study.; SECONDARY OUTCOME: 1. Pain at rest measured on a visual analogue scale (VAS) on the day after surgery and documented by the nurse on duty; 2. Complications. Wound status was documented daily. Oozing from the wound persisting beyond 2 days after surgery, bullae formation, subcutaneous hematoma that needed aspiration or surgical drainage, and wound infections that required additional treatmentssuch as antibiotic coverage or surgical debridement were recorded.; ; INCLUSION CRITERIA: Adults who have OA and need a total knee replacement.