Thrombocytosis after hip and knee surgery in the rehabilitation setting: is it an occasional phenomenon? Relationship with deep venous thrombosis and functional outcome

BACKGROUND Thrombocytosis can follow surgery and has occasionally been observed after major orthopaedic surgery. The aim of the present study was to ascertain the platelet count (PLTC) change in patients admitted to a rehabilitation unit after major joint surgery and whether deep venous thrombosis (DVT) and poor outcomes occurred in those who had thrombocytosis. METHOD PLTC, red blood cells (RBC), haemoglobin (Hb), fibrinogen, and D-dimers were assessed in patients on admission and at discharge after major joint surgery. Functional outcomes were ascertained using the Barthel Scale (BS), the Functional Independence Measure (FIM) and gait evaluation. Thrombocytosis was considered to have occurred when PLTC was greater than or equal to 500 × 100(9)/L. All subjects with thrombocytosis had ultrasonography to assess DVT occurrence. The patients were divided into "young" and "old" groups according to an age cut-off of 75 years to investigate potential age-related differences. RESULTS Two hundred and seventy-five patients were identified and 142 (36 M and 106 F, mean age 77.2 ± 10.7) were enrolled. Seventy-six (53.5%) underwent total hip arthroplasty (THA), 40 (51.1%) underwent hip internal fixation and 26 (18.3%) subjects underwent total knee arthroplasty (TKA). The young and old groups included 60 and 82 patients, respectively. Fifty-nine (42.4%) patients had PLTC above 400 × 100(9)/L. Of these, 28 (20.1%) had thrombocytosis with PLTC above 500 × 100(9)/L, and 15 of them (10.7%) had very high values above 600 × 100(9)/L. Increased levels of fibrinogen and D-dimers were also detected. No subject with thrombocytosis had DVT. Outcome was not affected by PLTC. At discharge, significant improvement in all functional assessments was observed in young compared to old people; gait: 2.9 ± 0.2 vs. 2.2 ± 0.8; BS: 97 ± 6.9 vs. 70.5 ± 25.6; and FIM: 116.4 ± 10.9 vs. 83.6 ± 31.2 (p < 0.004), respectively. BS and FIM mean scores were positively correlated with Hb level. CONCLUSION Elevated PLTC and thrombocytosis were not uncommon in patients after major joint surgery, but no subject developed DVT. Platelet count change did not affect the outcome. Higher age and lower haemoglobin level correlated with poorer functional recovery.