Abstract
Dear Sir
We have two principal concerns about the article by Lofterød and Terjesen, “Local and distant effects of isolated calf muscle lengthening in children with cerebral palsy and equinus gait”. First, after 15 years of continuous work in the Hugh Williamson Gait Laboratory, in which we have assessed several thousand children with cerebral palsy, we think we have only now found our first subject with diplegic cerebral palsy who might be a good candidate for isolated calf-lengthening surgery. We suggest that the indication for isolated calf lengthening in spastic diplegia is very small indeed and if over used is liable to result in calcaneus gait. The majority of our patients who appear to have a true equinus gait pattern have occult spasticity and/or contractures proximally that need to be dealt with at the time of surgery for equinus [1].
Second, in the selection of a calf-lengthening procedure for spastic equinus, we draw a sharp distinction between children with hemiplegia and those with diplegia. Children with hemiplegia typically have a contracture affecting both gastrocnemius and soleus, and lengthening of the Achilles tendon may well be appropriate. In children with spastic diplegia, the contracture affects mainly, sometimes only, the gastrocnemius and we think that lengthening of the Achilles tendon is over treatment for the majority of these patients. This is borne out by the kinematic data published by Lofterød and Terjesen, which quotes the mean maximum ankle dorsiflexion in stance as 10.9°, but the standard deviation to be 6.8°. This means that some of these subjects are already showing a peak dorsiflexion in stance of about 27°, which is well above the accepted normal range. It is our view that this will continue to increase and result in calcaneus at the ankle and crouch gait in due course.
Although the authors were kind enough to quote our extensive study of calf-lengthening surgery published in 2001, there is a crucial difference between the study by Lofterød and Terjesen and that by us (reported by Borton et al. [2])—with respect to the length of follow-up. The minimum follow-up in the study by Borton et al. [2] was 5 years and extended up to 10 years. During that time, we found that the correction of equinus contractures seemed to be very satisfactory in the majority of patients during the first 1–3 years after surgery. However, with each succeeding year of follow-up, more and more patients developed calcaneus at the ankle and crouch as their sagittal gait pattern.
Lofterød and Terjesen are in a position to provide very important information if they can follow-up and report their surgical outcomes at 5–10 years after the index surgery.
It is of interest that Rethlefsen and Kay have expressed similar concerns regarding another study reporting the outcome of Achilles tendon lengthening in spastic diplegia [3, 4].
Yours sincerely
H. Kerr Graham
Paulo Selber