Spastic cerebral palsy (SCP) is often associated with significant limb deformities in adolescence, including lower limb deformities such as hip adduction, knee flexion, and foot drop inversion. In infancy, these deformities are mostly dynamic and muscle contractures are rare. In adolescence, fixed muscle contractures can occur, leading to the development of corresponding deformities such as knee flexion and foot drop inversion. Most children with cerebral palsy in China fail to undergo early scientific and systematic intervention, resulting in the development of limb deformities and disabilities to a severe degree in many patients, so there are currently a large number of adolescents and adults with cerebral palsy in need of treatment in China [1].
In general, surgery is not recommended for deformities before the age of 3 years to avoid overkill. The best time for soft tissue surgery is when the child has developed to a stable gait, usually up to 5 years of age, and the surgical approach changes with the developmental status [2]. The early stage of spastic cerebral palsy is treated by selective posterior spinal nerve rhizotomy and anti-spasticity drugs, while the development of fixed deformities in adolescents often requires orthopaedic surgical intervention [3-7].
1. Pathogenesis and clinical characteristics of lower limb deformity due to spastic cerebral palsy
Spasticity is the result of injury to the upper motor neurons of the pyramidal system (cortical motor area), periventricular white matter, internal capsule, midbrain or pons, and corticospinal tract. Increased excitability of the detrusor reflex after loss of inhibition of the superior motor center in the spinal cord results in loss of voluntary control and abnormal balance. The CNS lesions in patients with cerebral palsy are resting, however secondary lesions in the skeletal-muscular system progressively worsen with growth and development until skeletal maturation [8]. It has been noted that in growing children with cerebral palsy, spastic muscle growth rate reaches only 55% of the skeletal growth rate, and lesions such as shortening of static muscle cell ganglia, muscle fibrosis, and contracture of muscle-tendon units can occur. Static muscle contractures can alter the muscle forces acting on the skeleton, resulting in restricted skeletal growth, angulation and rotational deformities. Both spastic motor imbalances and spastic lesions can lead to complications such as joint deformities, unbalanced skeletal growth with torsional force line misalignment of long bones, hip dislocation, spinal deformities, and chronic pain from intermittent or muscular spasticity [9,10]. Soft tissue surgery is often considered when persistent spasticity inevitably leads to deformity [11].
The range of spastic lower limb deformities is highly variable, from unilateral gastrocnemius contracture to multiple sites of soft tissue contracture and skeletal muscle deformities. The “progressive” progression of motor disability in cerebral palsy is often insidious, usually without significant orthopaedic difficulties in the first 10 years of life, but becoming increasingly evident thereafter. Thus, any spastic deformity of the limbs, especially the lower extremities, that has not been surgically corrected after preschool, will develop into bony deformity changes in adolescence, and will inevitably develop into severe soft tissue contractures and osteoarticular deformity changes in adulthood. For example, in patients with paraplegic and bilateral lower limb spastic cerebral palsy, if there is a lack of correct intervention and orthopedic treatment at an early age, they show a scissor gait in early childhood or childhood, and when they develop into adolescence or adulthood, a significant proportion of patients develop a squat gait with mild hip flexion, severe knee flexion, and femoral inversion, which seriously affects walking function [12].
2, Principles of orthopedic surgical treatment of lower limb deformities in spastic cerebral palsy
The choice of surgical modality follows the principle of individualization and needs to be based on the patient’s age, the degree of disease progression, and the type of deformity pathology (spastic, dynamic, or fixed). The treatment of spastic cerebral palsy is focused on spasticity (manifestation of conus systemic damage) and skeletal-muscular deformities caused by spasticity. The most prominent traditional treatments for cerebral palsy: orthopedic surgery and rehabilitation, are generally not spasticity-specific. Treatment aimed at simply correcting the limb deformity often results in a recurrence of the deformity due to the presence of spasticity. Therefore, how to relieve spasticity becomes the key to the treatment and rehabilitation of cerebral palsy. Currently, the main procedures for treatment of spasticity include selective partial spinal nerve rhizotomy (SPR) and selective partial peripheral nerve dissection. After six months of rehabilitation, orthopedic surgery is scheduled according to the remaining deformity of the limb. Orthopedic surgery is an adjunctive treatment for unsatisfactory relief of spasticity and fixation of joint deformity after neurological surgery. The principle of surgical treatment for spastic cerebral palsy is that neurological surgery such as SPR and peripheral nerve selective excision should be performed first to relieve muscle spasm, and orthopedic surgery such as tendon and soft tissue surgery and bone surgery should be performed second. Early SPR can reduce the rate of certain orthopaedic surgeries such as ankle or foot surgery, femoral osteotomy and skeletal and lumbar muscle release, and orthopaedic orthopaedic surgery is generally appropriate six months to one year after SPR [13].
3. Indications and contraindications for orthopaedic surgery
Indications for orthopaedic surgery
(1) Spasticity of the limb, marked increase in muscle tone, hyperreflexia, dyskinesia, and abnormal posture.
②The presence of dynamic, progressive or fixed joint deformity, orthopedic surgery to create conditions for the assembly of braces.
(③Severe spastic limb deformity, motor function may not improve after surgery, but it can provide convenience for life care. The main reason why some children with cerebral palsy cannot stand and walk is the existence of severe deformity of the lower limbs, which can obtain better function if given reasonable correction.
④ Age Generally, the upper limbs of patients over 7 years old and the lower limbs of patients over 3 years old, and the family or the patient has the desire and request for surgical treatment.
⑤Patients or family members can cooperate with functional training after surgery.
⑥No systemic or local diseases that affect the implementation of surgical treatment.
Contraindications to orthopaedic surgery
①Obvious surgical tachycardia.
②Severe coracoacromial deformity of the trunk.
③Limb deformity due to torsional spasm.
The above types should be treated by a neurosurgeon.
4. Common surgical methods for orthopedic treatment of lower limb deformity in spastic cerebral palsy
The ultimate goal of orthopedic surgical treatment is to improve the quality of patient survival, which mainly includes improving the motor function of patients, preventing secondary lesions, and correcting the patient’s morbid posture thus enhancing the ease of receiving health care [14-16]. Patients who are able to walk and present with progressively worsening joint contractures, deformities due to muscle imbalance, and rotational deformities of the limb generally require orthopedic surgical treatment, which commonly includes muscle lengthening and/or tendon transfers and osteotomies. The indication for tendotomy is very limited due to the risk of excessive postoperative muscle weakness. It should be avoided in children who are able to walk; instead, the technique may be considered in children who have lost the ability to walk, with the aim of improving the child’s posture and facilitating care. The goal of tendon transfer is to restore muscle balance. The indications for overall tendon transfer should be properly evaluated due to spastic muscle imbalance, and the outcome of the child after tendon transfer is difficult to predict. There is a greater likelihood of overcorrection, leading to an opposite deformity. The results of a partial tendon transfer are a little more reliable. After tendon lengthening or release surgery for cerebral palsy, good cast immobilization is an important step in obtaining a satisfactory outcome and should be done by the orthopedic surgeon who performed the surgery or assisted in finishing the tubular cast. The affected limb is more likely to be properly cast under anesthesia and muscle relaxation. Common surgical approaches include.
(1) Correction of hip adduction deformity: scissor step or scissor leg deformity is the most common deformity of spastic bilateral lower limb cerebral palsy, in which the legs are crossed in severe cases, passive hip abduction is difficult, and the patient is unable to complete the stepping action, and if it develops at least at term, it is easy to secondary hip dislocation and torsion deformity of the upper femur, which is also mostly accompanied by hip pain and difficulty in walking and sitting [17]. The direct cause of scissor step deformity is the spasm and contracture of the adductor femoris, and the surgical methods to release the spasm and contracture of the adductor femoris are generally divided into two categories, but regardless of the surgical method, the contracted adductor tendon should be moderately released at the same time. ① Weakening the muscle strength or tone of the adductor femoris: for example, selective posterior spinal nerve root dissection (SPR), superficial or full branch dissection of the closed foraminal nerve, and partial release of the beginning of the adductor femoris, especially superficial branch dissection of the closed foraminal nerve plus release of the beginning of the adductor femoris is very traumatic, simple and effective. However, the degree of release should be appropriate. Excessive release of the tone of the hip adductor muscle will reduce the stability of the hip joint and even lead to irremediable hip abduction deformity. ② Muscle displacement to increase the muscle strength or tone of hip abduction and external rotation: commonly used are semitendinosus or thin femoral muscle external to the femoral epicondyle, but the above two long muscles are mainly used to increase the role of hip external rotation after external placement. It has been reported that cutting down the beginning of the adductor and the thin femoral muscle at the pubic symphysis and transposing and fixing them to the sciatic tuberosity can release the hip internal deformity and increase the strength of the hip joint posterior extension [18-20].
(2) Orthopedic treatment of knee flexion contracture: The orthopedic treatment of spastic cerebral palsy with flexed knee gait can be summarized as follows: (1) non-knee surgery to indirectly correct the flexed knee gait: such as hip flexion correction, lever arm dysfunction correction, spastic or contracted hip flexor release and lengthening surgery. (2) Knee surgery for direct correction of flexed gait: knee muscle adjustment, posterior capsulotomy/supracondylar osteotomy or patellar ligament tightening. (iii) Remedial treatment of medically induced flexion of the knee gait: wearing three major types of orthopedic devices such as AFOs that control the ground reaction force exogenous to the knee flexion moment of the walking cycle [21-26].
(3) Correction of foot drop: spastic cerebral palsy can cause one or several of the following deformities of the foot: horseshoe foot deformity, foot valgus, supinated toe foot, [valgus, toe flexion, or claw toe. The indications for surgery for cerebral palsy foot deformities are relative. Severe horseshoe deformity or foot entropion deformity should be surgically corrected, and ectropion should also be surgically corrected if it affects function. However, in general, the patient must have the conditions to stand and walk, be basically normal in intellect and spirit, and a gait analysis should be performed before surgery. Surgical categories mainly include: ① tendon surgery: tendon lengthening or cutting, fasciotomy, tendon transposition, such as Achilles tendon, flexion [long tendon lengthening to correct bunion flexion contracture deformity. ② Bone surgery, such as tarsal osteotomy and joint fusion on the basis of soft tissue release to correct the bony deformity of inversion or valgus of the foot [27-29].
5. Surgical strategies and surgical complications of lower limb orthopaedic surgery for cerebral palsy
(1) Proper formulation of surgical plan
The basic principles of orthopedic surgery for cerebral palsy extremities are to improve pathological muscle spasm, correct limb deformities, equalize muscle strength, stabilize joints, and reconstruct the static and dynamic balance of the lower limbs [14,15]. This is the basis for the correct surgical plan. The criteria for the correct surgical plan are: the effect of improving spasticity and correcting deformity is real; there are no recent or long-term complications; as far as possible, the polyarticular deformity of the lower extremity is basically solved in one stage of surgery, which can facilitate the recovery of function and the rehabilitation of the organism; if two surgeries need to be performed, the former and later surgical effects do not affect each other.
(2) Application of combined surgery
Combination surgery was first proposed by Qin Sihe. The basic principle is that one or both lower limbs are designed as a surgical unit, and the surgical plan is formulated from the overall function of the lower limb movement, and different types of surgery and surgical methods are optimally combined together. One stage of surgery is required to correct multiple joint deformities to restore the line of gravity of the lower extremity, or one stage of surgery is required to improve spasticity, correct deformities, stabilize joints, and balance muscle strength for four purposes.
Orthopedic strategy and choice of surgical approach for combined surgery: overall consideration, individualized design, and different nature of surgery can be combined. In this way, both the deformity can be corrected and the cause of the muscle spasm causing the deformity can be removed. For example, tendon surgery, neuromuscular branch severance of spastic muscle groups and orthopedic surgery for bony deformities should be performed simultaneously. The first stage of surgery restores the gravity line of single or double lower limbs to create conditions for patients to stand. For example, the release of hip adduction deformity, flexed knee, clubfoot or horseshoe foot deformity can be solved in one surgery. Since more than 2 joint sites are to be implemented at one time on one or both legs, generally more than 4 or even 10 surgical approaches, reasonable arrangements should be made for the steps of surgery during surgery.
(3) Postoperative braking, lower limb plaster fixation technique and functional training
① Braking method should meet the following requirements: maintain the position needed for orthopedic surgery; braking material should be lightweight, reliable fixation, and will not produce damage to the skin compression; can not restrict the movement of large joints for a long time, especially the knee joint; during the braking period after lower limb surgery, it should be conducive to the patient to get out of bed early foot weight-bearing exercise walking. The economic simplicity and good shaping performance of plaster cannot be completely replaced by other materials at present. The use of various plaster fixation techniques and orthoses is one of the basic guarantees for good results in orthopedic surgery for cerebral palsy. The main applications of plaster are: at the early stage of limb deformity development, controlling the limb in functional position can avoid deformity, and applying the characteristics of plaster shaping can gradually correct some deformities of lower limbs, such as clubfoot and valgus foot, and knee flexion deformity. If there is no condition to wear a brace for knee retroflexion deformity, a tube cast can be used to fix the knee joint in mild flexion position for 3-6 months, which is beneficial to the standing and walking of the affected limb and can correct or partially correct the knee retroflexion deformity. Although internal fixation or external fixation through pins is done after osteotomy orthopaedic surgery, short-term braking with a cast in the position needed for orthopaedic treatment can reduce pain and limb swelling of the patient and help in early care. For various soft tissue release, tendon transposition, joint fusion, and osteotomy of the lower extremity, some patients may have the limb fixed in the orthopedic required position or functional position with a cast alone. In children, the spastic limb of the lower extremity is released under anesthesia and fixed in a functional position with a long-legged tubular cast, and then the cast is removed after 6 weeks for exercise and walking, which is found to relieve spasticity and correct joint deformity. In addition, it is necessary to make a model with a cast before making a brace.
② Functional training: The main goal of functional training is to enhance the strength of non-spastic muscles, improve balance function, avoid or reduce joint contracture, and improve motor function. The human neuro-skeletal muscles and the bones and joints connected to them fully follow the principle of using in and out to adapt to changes in needs, and the importance of functional training is even more emphasized in cerebral palsy patients. Correct and effective functional training in the early postoperative period can fully mobilize the patient’s subjective initiative and tap into his or her motor and life potential. Due to the change of mental state, it can act on other systems through the nervous system, so that the blood circulation of the whole body is increased, the function is active, the digestive function is increased, the metabolism is accelerated, and the tissue repair is promoted. The basic requirements of postoperative functional training: method, procedure, time and intensity depend on different types of cerebral palsy, type of surgery and fixation method. The general requirement is that for those who have braked the knee and ankle joints (long leg cast), especially for those who have done tendon transposition, the patient should be encouraged to do leg lifting exercises, isometric muscle contraction exercises inside the cast, that is, static strength (static strength) training, and joint activities at the end of the limb on the third day after surgery. Due to the muscle contraction of the affected limb, it can promote the venous and lymphatic return of the limb, reduce the adhesion between muscles and eliminate swelling; it can also slow down the muscle atrophy and give the physiological pressure to the osteotomy to facilitate its healing. With the development and application of new fixation materials and orthopedic devices, the method of limited motion has been gradually adopted after knee, ankle and foot joint surgery, i.e., the joint can intermittently do limited motion during the braking period, i.e., dynamic strength training, and the angle of braking can also be adjusted. Generally, one week after surgery, the patient can get out of bed and walk in a cast shoe with a walker. Some patients should wear an orthosis for a period of time after the cast is removed.
6.Application of orthoses in cerebral palsy rehabilitation treatment
For children with cerebral palsy, orthotics and assistive devices are mainly used to correct the deformity of the limbs or prevent the deformity from worsening through the action of force (such as the common three-point force principle). During the growth and development of children, the imbalance of body gravity caused by the imbalance of muscle strength and tone of various muscle groups or abnormal posture can easily cause secondary deformities of bones and joints.
② Orthotic treatment for children with pre-standing cerebral palsy: Children with pre-standing cerebral palsy spend a lot of time in a sitting position, which can lead to contracture of muscles and soft tissues of the hip, knee and ankle joints, causing hip flexion, knee flexion and horseshoe deformity. Since a considerable amount of muscles around the hip, knee and ankle joints span both joints, orthotic prescriptions need to consider controlling the two joints in question in order to prevent and correct lower limb deformities.
③ Orthotic treatment of children with walking cerebral palsy: Both spastic diplegia and quadriplegia present with extensive loss of neuromuscular function, the difference being that in diplegia the degree of paralysis is greater in both lower extremities than in both upper extremities, whereas in quadriplegia the degree of paralysis is similar in the upper and lower extremities. The clinical outcome of these children with cerebral palsy is not as good as that of children with hemiplegic cerebral palsy, but most of them can develop to walk independently or with the help of orthotics and walkers after the age of 4 years.
7. Summary
In conclusion, to determine whether a patient has indications for surgery is to analyze whether the conditions for improving spasticity and correcting deformity are available, and whether surgery can achieve the purpose of improving function and facilitating life. For patients with recurrence of deformity after previous orthopaedic surgery of the lower extremity, it is important to analyze the cause of the recurrence of deformity in the link, whether it is a combination of the choice of indications, surgical method, age of surgery, characteristics of the disease, postoperative rehabilitation methods, etc. In patients with both flexed knee deformity and horseshoe foot deformity, attention should be paid to analyze which group of deformity is the main one. If the patient has two opposite deformities in both lower limbs, such as clubfoot on one side and valgus on the other side, pay attention to the way of walking and the area where the foot lands, and study the causes of the foot deformity.
The complex lower limb deformities in juvenile spastic cerebral palsy require orthopedic intervention, but for severe deformities, it is difficult to obtain satisfactory results with soft tissue orthopedics alone, and osteotomy is more damaging to the body. Our recent clinical experience and treatment results confirm that the rational application of soft tissue orthopaedics combined with Ilizarov technique brings new hope for the correction and functional reconstruction of severe and complex deformities of lower limbs in cerebral palsy. After the application of this technique in patients with mild deformity, the chance of long-term recurrence is reduced because the tendons, muscles and joint capsule are ductilely orthopedic by slow pulling, and there is no skin incision scar. The indications for the Ilizarov technique, the slow and continuous tension stress, the ability to reduce neuromuscular spasm and the detailed technical details of clinical application, basic research, and long-term clinical follow-up need to be explored and summarized in depth.
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