Perioperative Care of a Patient with Refractory Idiopathic Thrombocytopenic Purpura Undergoing Total Knee Arthroplasty
A 61-year-old man with a history of ITP presented with chronic severe right knee pain. He had been suffering from ITP for eleven years and despite corticosteroids, dapsone and azathioprine treatment as well as previous splenectomy his platelet count remained in the range 20-30×109/L with occasional dips to <10×109.\nClinical examination of the knee revealed a correctable varus deformity of five degrees with no fixed flexion deformity and knee flexion of ninety degrees. The skin quality around the knee was satisfactory with no distal neuro-vascular deficit. Radiographs of the knee (, ) confirmed severe osteoarthritis with absent joint space in the medial compartment of the right knee. Considering the severe changes on the X-rays and effect on his quality of life a decision to undertake a right sided cemented knee replacement was made. The possible risks involved were discussed at length with the patient by both the orthopaedic and haematology teams. After careful consideration he consented to proceed with the operation.\nThe patient received 28 g of intravenous immunoglobulin (IV Ig) per day (equivalent to 400 mg/kg for a 70 kg person) for five days prior to the knee replacement. A platelet count of 280×109/L was achieved and it was deemed safe to carry out the procedure. As the patient had been receiving prednisolone at a dose of 10 mg daily for some months prior to the operation, hydrocortisone 150 mg was administered on the day of operation, according to the advice by the anaesthetic team. The operation was conducted under general anaesthesia with sciatic and femoral nerve blocks. Cemented total knee replacement was performed using midline skin incision with medial parapatellar approach. Cruciate retaining PFC sigma (DePuy Orthopaedics Inc, Warsaw, IN, USA) implant was used with Palacos cement (Heraeus, Wehrheim, Germany). Meticulous tissue handling was observed throughout the whole procedure. No alterations were made to the routinely used surgical technique and no drains were used at the end of the procedure. No additional blood conservation measures such as haemovac or cell saver were used. No particular difficulties were faced during the operation. A total tourniquet time of 75 minutes was noted.\nPostoperatively, the patient was particularly observed for excessive bleeding from the operative wound and his platelet count was monitored daily. Low molecular weight heparin which is routinely recommended for prevention of venous thromboemobolism in patients undergoing major joint replacement surgery, was not prescribed due to high likelihood of postoperative bleeding in this case. Also, non steroidal anti-inflammatory drugs which are known to cause platelet dysfunction were avoided. Instead, mechanical thromboprophylaxis was used with anti-embolism stocking sand intermittent calf compression pumps.\nOn postoperative day one platelet count was 140×109, on the second day platelet count dropped down to 137×109 and on the third postoperative day it was 73×109. In view of this, 28 g (400 mg/kg) of IV Ig per day was commenced on the third postoperative day for another three days after discussion with the haematology team. At this stage, low molecular weight heparin was commenced to counter the hypercoagulability state known to be caused by intravenous immunoglobulins. His platelet count dropped down to 37×109 on postoperative day four. On day seven the platelet count improved to 190×109.\nRoutine postoperative ambulation was carried out. The patient was mobilised with the aid of crutches initially. He was discharged from the hospital on the eighth postoperative day after achieving independent walking with stair climbing and knee flexion of 80 degrees.\nThe patient was reviewed in the haematology clinic three days following discharge from the hospital. The platelet count measured then was 327×109. His platelet count trend is shown in . He was reviewed in the orthopaedic clinic after one week, three week and six weeks. The postoperative radiographs of his knee were satisfactory (, ). No complications were observed. At three months follow-up 130° of knee flexion was achieved. His postoperative Oxford Knee score was calculated to be 40. The patient was able to carry out all the activities of daily living including driving and he was very satisfied with the outcome.