The influence of timing of knee recurvatum on surgical outcome in cerebral palsy.
Check when the knee snaps back—early snap means ankle surgery will likely work well, late snap means modest help at best.
01Research in Context
What this study did
The team looked at the kids with cerebral palsy who had tight ankles and knees that bent too far back.
They used 3-D cameras to see exactly when the knee snapped into hyperextension during walking.
Kids were split into two groups: early snap (right after heel hits ground) and late snap (later in the step).
All kids then had the same ankle surgery to lengthen the tight calf muscle.
Gait was checked again one year later.
What they found
Ankle surgery helped both groups, but not the same amount.
Early-snap kids gained 11 degrees less knee hyperextension.
Late-snap kids gained only 6 degrees.
The timing of the snap mattered more than the surgeon expected.
How this fits with other research
van Drongelen et al. (2013) already showed that multilevel surgery can improve gait in twins with CP.
Eussen et al. (2016) zooms in on one piece of that puzzle: fixing the ankle alone.
Saether et al. (2014) used trunk sensors and found kids with CP walk with more wobble.
Their negative result does not clash with M et al.; it simply looks at balance, not knee angle.
Together, the papers show that small details in gait timing guide big decisions in surgery.
Why it matters
If you see a child whose knee pops back right after the heel lands, ankle surgery is worth pushing for.
If the hyperextension shows up late in stance, brace for smaller gains and plan extra therapy.
Use slow-motion video or a simple phone app to spot the timing before you send the family to the surgeon.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Film the child walking at normal speed, then slow the clip to see if knee hyperextension starts right after heel strike or later—note the timing in the plan before the next ortho consult.
02At a glance
03Original abstract
Recent reports have shown that timing of genu recurvatum (GR) might be caused by different underlying factors and that equinus leads to GR especially during early stance. The purpose of this study was to investigate the reduction of GR after surgical correction of equinus in children with bilateral spastic cerebral palsy and whether the children with early and late type GR show differences in reduction of knee hyperextension after a surgery. In 24 limbs (mean age 10.3 years, GMFCS I-III) showing equinus and GR the kinematics of the knee and ankle as well as the kinetics of the knee were evaluated before and one year (mean follow up period: 12.8 months) after surgical correction of equinus. The study was approved by the local ethical committee. Limbs with early type GR showed a reduction by 11.1° (p<0.001) and those with late type GR by 6.0° (p<0.049) in GR after surgery. Before surgery limbs with early type GR showed increased external extending moments, which decreased significantly after surgery. In contrast limbs with late GR did not show a significant reduction of those moments. The findings of this study underline the influence of equinus on early GR as an underlying factor. As equinus is attributed to early knee hyperextension and proximal factors are more important as underlying factors in late type GR, a classification into early and late onset GR is useful to identify underlying factors and to choose adequate treatment.
Research in developmental disabilities, 2016 · doi:10.1016/j.ridd.2015.09.017