Spontaneous Decrease of Gastrocnemius Spasticity after Correction of Knee Flexion Gait in Cerebral Palsy Children

Review Article

Phys Med Rehabil Int. 2018; 5(5): 1159.

Spontaneous Decrease of Gastrocnemius Spasticity after Correction of Knee Flexion Gait in Cerebral Palsy Children

Low WMT1¹, Wang SM², Yeh KK³ and Chang CH¹*

¹Department of Pediatric Orthopedics, Chang Gung Memorial Hospital, Taoyuan, Taiwan

²Graduate Institute of Early Intervention, Chang Gung University, Taoyuan, Taiwan

³Department of Physical Therapy and Graduation Institute of Rehabilitation Science, Chang Gung University and Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital , Taoyuan, Taiwan

*Corresponding author: Chia-Hsieh Chang, Department of Pediatric Orthopedics, Chang Gung Memorial Hospital. 5 Fu-Hsin Street, Kueishan Area, Taoyuan City 333, Taiwan

Received: November 04, 2018; Accepted: October 10, 2018; Published: December 17, 2018


Purpose: Synergistic neuro-excitability in the lower extremities may be related to gait disorders. This study reported spontaneous changes after correcting knee flexion gait and discussed the underlying mechanisms.

Methods: A prospective study of 23 children with cerebral palsy was conducted to assess postoperative changes in gross motor function, joint range of motion (ROM), and spasticity. Characteristics of children/limbs with spontaneous decrease in gastrocnemius spasticity were assessed.

Results: In 10 patients (19 limbs) without gastrocnemius release, Modified Ashworth scores in the gastrocnemius decreased in 6 limbs after 3 months and in 10 limbs after 6 months. Those limbs had worse preoperative knee flexion contracture than limbs without spasticity changes (knee ROM limitation score 5.4 vs. 3.7, p=0.026).

Conclusions: Patients with knee flexion contracture recruited greater plantar flexion-knee extension couple and enhanced synergistic neuroexcitability. Careful surgical decision-making by neuro-excitability, which is susceptible to other co-existing disorders, is important.

Keywords: Spasticity; Gastrocnemius; Hamstrings; Cerebral palsy


CP: Cerebral Palsy; ROM: Range of Motion; ICC: Intra-Class Correlation Coefficients; MAS: Modified Ashworth Scale; GMFM: Gross Motor Function Measure; GMFCS: Gross Motor Function Classification System

Level of Evidence

Case-control study, Therapeutic; Level III.

What this Adds to the Evidence

Synergy between different muscles affects motor control and gait function in patients with cerebral palsy. We found enhanced synergy between the hamstrings and gastrocnemius in children with more severe knee flexion contracture. When the hamstrings were released surgically, spasticity in the gastrocnemius was reduced spontaneously.


Cerebral palsy (CP) is a disease caused by non-progressive injury to the immature brain. Spasticity, muscle contracture, and subsequent limited range of motion (ROM) are common disorders that cause dysfunctions in gait and posture [1,2]. A common pathologic gait pattern in children with CP is knee flexion gait, which is characterized by increased knee flexion throughout the stance phase of the gait cycle. Knee flexion gait incurs more energy for walking and can be classified as jump knee gait, apparent equinus gait, and crouch gait by different biomechanics in the ankle [3]. Multilevel surgical correction is recommended for treating knee flexion gait to prevent decline in ambulatory ability [4].

Synergistic movement is a common neuropathological sign in patients with stroke and encephalopathy [5]. The primitive movement pattern interferes with coordinated voluntary movements. For example, patients with flexion synergy in the upper limbs show scapular retraction, shoulder adduction, elbow flexion, and wrist and finger flexion at the same time. Patients lose independent control of selected muscle groups, resulting in coupled joint movements known as abnormal synergy that is often inappropriate for the desired task [5]. Synergistic movement also occurs in the lower extremities as shown in hip flexion-adduction, knee flexion, and ankle plantar flexion.

When the hamstrings and gastrocnemius are regarded as one synergistic muscle group, the two muscles relate to each other. When one muscle is changed, the other muscles in one synergistic group may also be affected. Since surgical release is a strong perturbation for a muscle, we speculate that releasing the hamstrings may affect the gastrocnemius, and vice versa. In a clinical scenario where hamstrings are released for knee flexion gait, the gastrocnemius may be inoperable to preserve the plantarflexion power. It offers a chance to investigate how the non-operated gastrocnemius responds to surgical interventions if the hamstrings and gastrocnemius belong to one synergistic group. In this study, we aimed to show spontaneous changes in the length and spasticity of the gastrocnemius when surgery is performed in the hamstrings and to investigate the characteristics of the patients or the limbs with spontaneous change.

Materials and Methods

After approval from the Institutional Review Board of our institution, a prospective study of surgical outcomes after myofascial release was conducted in 25 children with CP between 2010 and 2013. The children participated in the study, with a mean age of 8.5 years (3.5 to 12.8) before multilevel surgery for spastic knee flexion gait. Signed consent forms were obtained from all the participants’ parents. There were 17 boys and 8 girls. Their gross motor function was level II in 9 patients, level III in 11 patients, and level IV in 5 patients by the Gross Motor Function Classification System (GMFCS) [6].

Single-event multilevel myofascial releases of both lower extremities were performed in all patients. The surgery involved the muscles at the knees, hips, and ankles based on clinical judgment by gait characteristics and physical examination [7]. Surgical procedures performed around the hips were release of the adductor longus and gracilis for scissoring and/or the psoas for hip flexion contracture greater than 20° by the Thomas test. Surgical procedures around the knees were performed for the myofascial release of the semimembranosus and semitendinosus muscles for patients with knee flexion gait and the popliteal angle greater than 70°. Knee flexion gait was defined by knee flexion angle greater than 30° throughout the entire stance phase. Surgical procedures performed around the ankles included release of the gastrocnemius for static equinus at knee extension with positive Silfverskiold test. Patients who underwent osteotomies were not included in this study. After surgery, long-leg splints were applied for 2 weeks to facilitate training of standing with full extension of the knees. Non-articulated or ground reaction anklefoot orthoses were applied for gait training. Postoperative physical therapy was conducted by two certified pediatric physical therapists.

Muscle length was assessed by joint motion using a goniometer. The Spinal Alignment and Range of Motion Measure was an ordinal score to measure limitations of ROM [8]. The hip was assessed according to 6 items including extension, flexion, abduction, adduction, external rotation, and internal rotation. ROM limitation of the knee was assessed by 2 items, namely, the knee extension and the hamstrings. Knee extension was assessed by the maximal angle of passive knee extension at hip extension and was classified as follows: 10° or greater; 20° to -10°; 3, -10 to -20°; and 4, more than -20°. The hamstrings were assessed by maximal angle of passive knee extension at hip flexion 90°. They were classified as follows: 1, less than 20°; 2, 20 to 45°; 3, 45 to 60°; and 4, more than 60°. ROM limitation of the ankle was assessed by 2 items, namely, dorsiflexion and plantarflexion, that were assessed at knee extension. ROM limitation of ankle dorsiflexion was a measure of gastrocnemius length and classified as follows: 1, more than 15°; 2, 5 to 15°; 3, -10 to 5°; and 4, more than -10°. The Spinal Alignment and Range of Motion Measure that was performed at 2-week interval had good test–retest reliability (intraclass correlation coefficients (ICC) 0.95-0.97) and good interrater reliability between the two physical therapists (ICC 0.89).

Muscle spasticity was measured using the Modified Ashworth Scale (MAS) [9]. This 5-point scale was scored as follows: 1, normal tone; 2, mild spasticity with catching in limb movement or minimal resistance throughout the remainder (<50%) of the ROM; 3, moderate spasticity with increased tone throughout most of the ROM; 4, severe spasticity with difficulty in passive motion; and 5, extreme spasticity with rigidity in flexion and extension. Spasticity was assessed at the hamstrings and gastrocnemius. The MAS scores were regarded as an ordinal variable. The MAS that was validated before the study showed good test–retest reliability (ICC 0.76–0.79) and interrater reliability (ICC, 0.86).

Gross motor function was evaluated using the Gross Motor Function Measure (GMFM), which is a standard measure to quantify gross motor ability in children with CP [10,11]. In this study, the GMFM-66, which was a modified scale to improve the interpretability of changes following the interventions, was used [12]. Higher scores indicated better gross motor function. The GMFM scores were regarded as continuous variables in this study. The test– retest reliability and interrater reliability were excellent (ICC, 0.997 and 0.998, respectively).

Each patient underwent assessments at the week prior to surgery and post-operative 3 months and 6 months. Outcome measures included the MAS, ROM, and GMFM. All these measures were performed by two pediatric physical therapists. The surgical effects for all three outcome measures were compared before and after the surgery using a paired t-test. The characteristics of patients with spontaneous change at the gastrocnemius were compared with those of patients without change using t-tests for continuous variables (age, body mass index, ROM scores, GMFM-66 scores), Mann- Whitney test for ordinal variables (MAS scales), or chi-square test for categorical variables (GMFCS, surgery). The possibility of a positive significant factor to be associated with spontaneous change was further analyzed using an odds ratio and 95% confidence interval. A threshold for significance was set a priori at p<0.05. All analyses were conducted using SPSS version 21.0.


Twenty-five children with spastic diplegic or quadriplegic CP received bilateral multilevel myofascial release. Two of these children (2 girls, one GMFCS level III and one level IV) did not complete the post-operative assessments, and the other 23 children with 46 limbs were the study participants. All the limbs had myofascial release in two or more muscle groups (Table 1).