Author's response to reviews Title:Correlates of functional ankle instability in children and adolescents with Charcot-Marie-Tooth disease Authors:

results – “female gender (r = -.469, P < .001) and impaired balance (r = .495, P < .001).” Foot and ankle variables – “No significant gender differences (P <.05) were observed for age,” Variables associated with ankle instability – “Factors significantly associated with right FAI included female gender (r = -.469, P < .001),” “Factors associated with left FAI included female gender (r = .396, P < .05),” Table 2. Col 3 These should be corrected throughout. Authors’ reply: We have now used point biserial correlation to correlate with FAI with male/female gender. As the procedure for point biserial correlation in SPSS is the same as that for Pearson’s correlation these results remain unchanged. Minor essential revisions Reviewers’ comment: BACKGROUND – 2nd para. The assertion that the cavus foot is cardinal manifestation and may be another cause of FAI is overstated unless referenced to a definitive study. It may be associated but causality is being assumed here, rather than having been established. Authors’ reply: The second paragraph has now been amended so as not to overstate pes cavus as a potential cause of FAI in CMT. A reference has been included which is supportive of foot deformities such as pes cavus, predisposing an individual to FAI. Para 1, Pg 6: “High rates of cavovarus deformity have been reported in individuals undergoing surgery for chronic FAI (8). Pes cavus is a frequently reported manifestation of CMT..The excessively supinated foot structure associated with the cavus foot type might predispose the ankle to recurrent episodes of plantarflexion and inversion injury, particularly when it is coupled with foot and ankle strength imbalance” Reference (8): Larsen E, Angermann P. Association of ankle instability and foot deformity. Acta Orthop Scand. 1990;61(2):136-139.