DEFINING THE COMPLEX IDIOPATHIC CLUBFOOT AND ITS TREATMENT OUTCOMES

Some idiopathic clubfeet are considered complex (Type II) as opposed to classic (Type I). They are typically short, pudgy, puffy red feet with a transverse crease and cock-up toe. In another study, we highlighted some complex clubfeet have features present at birth (Type IIa) or while others develop complex features during Ponseti treatment (Type IIb). The outcomes of complex feet are generally found to be worse, however no prior work to our knowledge has distinguished outcomes based when the features of complex feet are identified. This is an observational cohort study of idiopathic clubfoot patients enrolled in a Research Registry and treated from 01/2010 to 06/2022. Clinical features, treatment data, relapse and surgical rates were compared. Patients were classified to have Type I, Type IIa or Type IIb feet. Descriptive, t-tests, Fisher exact tests were performed, as well as ANOVA for univariate logistic regression to determine factors associated with relapse and need for surgery. Of 368 children, 536 feet were included with 395 (74%) classic, 43 (8%) Type IIa, 98 (18%) Type IIb feet. Feet with complex features (transverse crease, short/chubby foot, severe cavus, weak toe extension) were significantly associated with risk of relapse (P < 0 .001 for all features) and require more casts (5 vs 4; P < 0 .001). Feet that required adjustment of the Ponseti method with the “double thumb technique” and decreased abduction in brace (£ 45 deg) were also more likely to relapse (p < 0 .001). The relapse rate was higher in complex feet (50/141 [35%]) than in classic (69/395 [18%], p < 0 .001), and but highest in Type IIa feet over Type IIb (19/43 [44%] vs 31/98 [32%], p=0.21). Similarly, surgical rates for relapsed or resistant feet were higher in complex 19/141 (13.5%) vs classic 19/395 (5%) (P=0.005), and while the surgical rate in Type IIa 9/43 feet (21%) was over twice as high as in Type IIb 10/98 feet (10%) it did not reach statistical significance (p=0.15). Relapse and surgery rates were significantly higher in complex feet than classic feet. Clubfeet with complex features at birth (Type IIa) had higher surgery and relapse rates than feet that developed complex features during treatment (Type IIb). This is the first study to report of worse outcomes for patients with complex features at birth. This classification of complex clubfoot to distinguish those with features seen at birth and feet that develop features during treatment is needed to enable better counselling for families on outcomes and for guiding clinicians in their treatment plans.