progressive paralytic equinovarus is an important reason for gait deterioration in pts w/ DMD;
equinus contracture compensates for incr quadriceps weakness & allows knees to lock by enabling wt line to pass in front of knee joint;
feet become progressively fixed in equinus & then equinovarus position;
posterior tibial muscle retains good f(x) despite progression of muscle weakness in other areas;
Indications for Surgery
progressive, rigid equinovarus contractures prevent pt from attaining comfortable position of feet in wheelchair or from wearing shoes;
surgical correction of equinovarus is indicated in pts who retain ability to ambulate;
if there are equinus contractures of the ankle but the function of quadriceps is still good, isolated Vulpius heel-cord lengthening is often valuable;
some authors have performed Z-lengthening but have cautioned about possibility of overcorrection;
procedure can add an average of 3 yrs of f(x) ambulation;
Operative Treatment
multiple tenotomies of Achilles, posterior tibial, FDL & FHL tendons, followed by use of AFO, has led to improvement in circulation & in position and comfort of the feet of these patients;
posterior tibial muscle retains good f(x) despite progression of muscle weakness in other areas;
its transfer thru interosseous membrane to dorsum of foot (lateral cuneiform) prevents recurrence of equinovarus & actively contributes to dorsiflexion of the foot;
