Joost Peerbooms

112 Chapter 7 Figure 2. For the platelet-rich plasma group (blue) and the control group (red), change in out- come over time. Values are presented as mean ± SD. AOFAS, American Orthopaedic Foot & Society; FFI, Foot Function Index. Based on the mixed model analysis only the change in FFI Pain scores differed significantly between the treatment groups. Inspection of Figure 2 indicates that both treatment groups show decreased pain over time. In the control group the pain scores decrease quickly after the treatment and then remain stable during the follow-up. In the PRP group the pain reduction is more modest yet reaches a lower point at the 12- month follow-up than the control group. This finding is confirmed by the analysis of covariance reported in Table 3. After adjusting for baseline differences in FFI Pain scores, the patients in the PRP group showed significantly lower pain scores than patients in the control group (mean difference, 14.4; 95% CI, 3.2-25.6). Although the mixed model analysis did not indicate a significant treatment effect for the FFI disability outcome, the analysis of covariance suggests that after adjusting for baseline differences, patients