Outcome of Correction of Spastic Equinus Deformity in Cerebral Palsy

Numerous procedures have been used in the treatment of equinus contracture with variable success rates. The surgical management of the ankle equinus is a widely debated topic and procedure selection is often based on surgeon preference because there is no consensus regarding the superiority of a single procedure.

The recurrence rates in the literature ranges from 0% to 50 %, depending on the type of the patient and length of the follow up. Over lengthening of the gastrosoleus should be avoided because it can cause weakness in push off and crouch gait. Because over lengthening is much less common with a gastrocnemius recession , surgeons prefer this procedure and reserve TA lengthening for patients with severe equinus deformities that cannot be corrected by recession.

The current study demonstrates improvements in both static and dynamic measures following surgical lengthening of the triceps surae in children with spastic equinus deformity. The improvements are significant. The decision-making between TAL and gastrocnemius recession was generally based on the results of static examination (including the Silfverskiold test) which was performed under anaesthesia. A positive Silfverskiold test was indication for gastrocnemius recession procedure and a negative test for TAL. The procedure selected using these criteria produced good results overall.

In our study, it was seen that the mean age of TAL patients was 8.87 yr. It may be due to the time period needed for contracture to develop in triceps surae is longer than gastrocnemius. It seems that gastrocnemius is involved earlier than soleus in pathological process of contracture formation due to spasticity. This difference may be due to the length of the musculotendinous unit, activity level of muscle and role in gait and balance.

It was seen that M: F ratio was almost 1:2. This led to inference that females which are affected with this deformity were brought for treatment at a later age than boys. This may be due to poorer health care concern for female child in a male dominant society as seen in this part of country.

It was seen that illiteracy was profound in study population. Other important reasons for delay in seeking medical advice are financial constraints and lack of awareness. Although financial constraints cannot be resolved to a major extent in a short time, negative impacts of financial constraints and lack of awareness can be addressed by setting up specialised cerebral palsy clinics at district and tehsil levels and launching awareness programs to be conducted in these distant rural settings as well as improved mother and child care services to decrease the etiological factors. Awareness should be created not only for disease aspects, but also about facilities offered by the government and help them avail them to the fullest.

In this study the etiological basis of majority of the subjects was found to be delayed cry or hypoxic ischaemic encephalopathy followed by preterm. We found that most common type of CP was diplegic type (54%), quadriplegic (30%), followed by hemiplegic (16%) . No patient was found to have monoplegia. Vlachou et al (2009) reported distribution in 135 consecutive patients as spastic diplegia 66.66%, hemiplegia 20%, quadriplegia 10.37% and monoplegia 0.74%.

The study showed that the mean popliteal angle increase significantly after the treatment and at final evaluation was 1.7%. The study showed that the mean Passive ankle DF in Knee extension angle increase significantly after the treatment and at final evaluation was 22.25° (20.9%).

The comparison of mean Active Ankle DF in Knee extension angle showed insignificant (F=2.67, p=0.08) effect of treatment, that is, not change significantly. This indicates minimal effect of surgical procedure on muscle power.

Although spasticity is difficult to be defined clinically, attempts have been made to define it, as the difference between initial grab with fast stretch, and end of range (EOR) with slow stretch (Tardieu G et al 1987)12. According to this, the reduction of quick stretch value seems to be a better indicator of the functional improvement than end of range, as spasticity is velocity dependent. We observed insignificant decrease in spasticity in terms of change in ankle grab angle as measure of fast stretch, change in ankle DF angle (EOR) and the difference (∆ml). Difference in initial grab and end of range (∆ml) was found insignificant at 8.07° in our study. Vlachou et al (2009)9 reported 14° improvement in the Ankle DF angle (EOR) and 18° improvement in ankle grab angle and difference in ∆ml being significant. The difference in result of our study from above mentioned study may be due to difference in sample size, low inter and intra-rater reliability of Modified Ashworth Score, and clinical grade at start of treatment.

Evaluation of spasticity according to Modified Ashworth Score showed insignificant effect on grading. Reduction of at least one grade was seen in 12.5% in study group. Spasticity did not changed significantly with surgical procedures. Similar results were reported by Kay et al (2004). Vlachou et al (2009) reported that Ashworth scale was reduced by at least one grade in 78% of subjects in the triceps surae group of the children with preoperative Ashworth 3 and above. Such difference in results may be due to differences in initial status of patient, age at which surgery performed, amount of contracture present in treated muscle groups, stretch ability of muscle / soft tissues in that region. Further, Kay et al (2004)11, (n=55) found mean postop change in spasticity to be similar to our study result (Kay- 0.1, ours- 0.13). Thus, it can be concluded that although surgical procedure have a decremental effect on spasticity, further evidence is required with increased sample size and longer follow up.

Comparing the mean GMFCS grading of the subjects of our study, we found insignificant change (p>0.05). It is rather clear that the reduction of spasticity, as well as, the responsiveness of the patients to the surgical intervention are strongly related to the preoperative passive and active range of motion of the joints, the structure of the muscle (length of muscle fibre, length of tendon, pennation angle), the preoperative level of spasticity, the baseline of GMFCS (Gross Motor Function Classification System) level and the age of the patient. Abel et al13 (1999) reported improvements in walking ability and stride length at 6 months after surgery and were maintained at two years after surgery, but the overall score of the GMFM (Gross Motor Function Measurement) level showed minimal change. Similar trend in GMFCS was seen in our study too with change in GMFCS level being insignificant at p>0.05.

The results were satisfactory in our study with good healing in all surgically treated patients. No infection occurred in any of the subjects.

Qualitative parent satisfaction and compliance of caregivers and patient were assessed at each visit in follow up. We found good parent satisfaction and compliance to treatment (drop-outs in study being 1). PJ Flett et al16 (1999) stated that there is increasing evidence that patient satisfaction has a significant influence on the effectiveness of services: greater satisfaction with health services is associated with better treatment compliance, less premature 'drop-out' from treatment, and less delay in seeking further treatment.

In our study, recurrence rates were found to be nil within the follow up period. This may be due to limitation of our study with very short follow up period of two year. No case of calcaneus deformity was seen. Rattey et al (1993)14 reviewed 57 patients with 77 TAL surgeries and after follow up of 10 yrs reported half of children 3 years old or younger at the time of surgery had a recurrence of deformity compared with no recurrence in children who were at least 6 years old at the time of initial procedure. Olney et al (1988)15 reported 48% recurrence after gastrocnemius recession if surgery was performed before five years of age. Craig et al (1976)11 reported 9 percent recurrence in 100 limbs operated by gastrocnemius recession in spastic equinus cerebral palsy children. Recurrence was 11 percent in 0-5 yr, 4.3 % in 6-10 yr and no recurrence found in 11-15 yr age groups. These reports are in compliance with our study results. Assumptions can be made that the rate of recurrence in surgical correction of equinus deformity decreases as the age of child increases and can be used in planning of timing of surgery and procedure. Early surgery may have an unpredictable outcome and recurrent equinus is related to the age of surgery7,8,14 . JC Borton et al (2001)8 reported sharp rise in good results and a dramatic fall in poor calcaneus results in those over eight years at surgery. In patients undergoing surgery at over eight years there was a good outcome in 70% and a calcaneus outcome in 17% compared with 37% and 46%, respectively, in those under eight years (p = 0.046). Further, they recommended preoperative gait analysis, postponing surgery until after the age of eight years, carrying out simultaneous proximal lengthening of the hamstrings and psoas when appropriate, and using a selective gastrocnemius lengthening procedure in spastic diplegic patients.

Conclusion

We conclude that surgical method used by us in our study is a useful method to treat spastic equinus deformity. Conservative methods are rapid, cheap and dependable method for correcting dynamic or mildly fixed equinus in young children. Intensive physiotherapy is indispensable after all the procedures to maintain correction and can be a useful adjunct to neurodevelopmental therapy programme to facilitate motor skills in children with cerebral palsy. For the spastic patient, particularly in dealing with lower extremity deformities, it is felt that a trial of conservative management may be given before any surgical procedure to assess compliance with post-operative program by the patient and to get an idea as to whether cooperation can be expected for proper post operative care. The current study reports good results following TAL in appropriately selected children with spastic equinus deformity. We suggest that the physician decide between conservative or surgical based on CLINICAL evaluation.