Joost Peerbooms

44 Chapter 3 Reported pain was reduced from (moderately) painful to mild pain 6 weeks postoperatively. There was a trend to greater pain reduction (both at rest and while walking) at 6 weeks postoperative for the C group. The median frequency of medication use was “sometimes”, and this remained the median answer though out the study period. There was no difference in reduction of pain medication use between the PG group and C group neither at 6 weeks post-surgery ( P = 0.9) or at 3 months ( P = 0.1). As expected, during hospitalization the range of motion of the operated knee increased from50 degrees 2 days post-surgery to 75 degrees at discharge fromhospital. During these days no benefit was seen for the PG group (2-way ANOVA, P = 0.7). From2 weeks, 6 weeks up to 3 months follow-up, no differences were seen between the two groups (p = 0.9). At 6 weeks post-operative the self-rated knee function (WOMAC score) had increased by 20 points, but the recovery rate between the two groups was similar (Mann-Whitney U test, P = 0.7; 95% CI: -8 to 8 difference); similarly, there were no differences between groups at 3-months follow-up (95% CI: -6 to 1 difference). Complications After discharge from hospital, superficial wound infections occurred in 2 patients (1 in each group; both coagulase-negative Staphylococcus); these infections were successfully treated with antibiotics. No deep infections were seen. DISCUSSION In this randomized studywe found no effect of wound healing of platelet gel used after TKA. PG is promoted as an ideal autologous biological blood-derived product, which can be exogenously applied to various tissues where it releases high concentrations of platelet growth factors that enhance wound healing. In addition, PG possesses antimicrobial properties that may contribute to the prevention of infections. 9 When platelets become activated, growth factors are released and initiate the body’s natural healing response. The actual quantity of platelets needed to achieve an improved outcome when PG is used is still questionable. Marx et al. 18 found in their study that a 3-4 times higher platelet count improved the mandibular continuity defects. The GPS system that we used produces a 6-8 times higher platelet count. Much higher concentrations might have an inhibitory effect. 25 The activator for the platelets we used was a mixture of thrombin and calcium chloride. After combining these substances, platelet-rich gel is formed, and numerous regulatory molecules and antimicrobial proteins are released to the injury site. 26 Thrombin derived from bovine plasma is used in the USA, despite