Disorders of the Brain

Muscle Tone

Physical examination of a child with CP should include muscle tone in the extremities. With the patient relaxed (even sitting on the lap of a parent), the extremities are brought through a full range of motion. Spasticity feels like tightness in the muscles, which become tighter the quicker the limbs are passively moved. Greater range of motion can be gained by slowly and gently stretching the joints in question. The Tardieu test is a measure of spasticity. For example, if the examiner is assessing hamstring spasticity, the angle at which a “grab” of resistance occurs when quickly extending the knee with the hip in flexion is compared with the amount of extension possible when the knee is stretched slowly.

Fine motor activities should be assessed. Passing the child a toy or a pen often reveals spastic hemiplegia in one extremity. Having the child clap the hands or wiggle the fingers may reveal difficulties in fine motor control.

Reflexes

Deep tendon reflexes are increased in patients with CP. Repetitive tapping of the deep tendons or quick passive dorsiflexion of the ankle may produce clonus, which establishes the presence of an upper motor neuron neurologic abnormality. In hemiparesis, reflexes will be asymmetric.

Infantile reflexes disappear in normal children by 3 to 6 months of age as the motor cortex matures; however, they are retained in children with CP. Bleck’s textbook on CP outlines these reflexes in clear detail. The startle reflex, or the Moro reflex, which should disappear by 4 months of age, is elicited by letting the infant’s head drop back into extension with the infant supine but slightly elevated. This causes the legs and arms to extend abruptly. A sudden loud noise can likewise cause an older child to extend and lurch from a wheelchair. The parachute reflex is tested by holding the child in the air and then lowering him quickly headfirst toward the examining table. Children older than 5 months will reach out with both arms to protect themselves. Children with CP cannot do so, and those with hemiplegia will reach out with only one arm.

The tonic neck reflex is elicited by turning the supine infant’s head to one side. The ipsilateral arm and leg will extend while the contralateral arm and leg flex. This reflex should disappear in infancy; persistence should raise suspicion for CP.

Balance, Sitting, and Gait

Balance, sitting, and gait are assessed by noting whether the child can sit unsupported without use of hands or get into a sitting position without assistance or whether balance is easily disturbed in the sitting position or as the child walks.

Clinical assessment of gait requires that the child’s joints be readily seen, so the child should be barefoot and in shorts or a short gown. The evaluation should be conducted with the examiner seated on a stool at the level of the child. Enough room should be available for the child to walk naturally. Heel-to-toe walking, hopping on either foot, and running are observed. A patient with mild hemiplegia may walk nearly normally but exhibit abnormal movement patterns while running; the affected upper extremity will draw upward and not have a normal arm swing.

Gait should be observed from the front of the child and then from the side, and the hips, knees, and ankles should be systematically assessed from each perspective. A crouched gait consisting of increased flexion at the hip and knee, toe-walking with genu recurvatum, or a footdrop in the swing phase of gait may all be indicative of CP. Disturbance in clearance of the swing-phase limb may be caused by footdrop or an inability to flex the knee.

Histopathologic and Imaging Findings

Two findings frequently described on histopathologic examination or imaging studies of the brain in children with CP are periventricular leukomalacia and intraventricular and periventricular hemorrhage. Periventricular leukomalacia is defined as patchy areas of necrosis in the periventricular white matter adjacent to the lateral ventricles. It results from an ischemic insult to the arterial watershed area close to the ventricular walls. Pyramidal tract fibers mapping to the lower extremities pass through this area and are therefore more susceptible to injury than fibers responsible for the upper extremities and face.

The areas of the brain immediately adjacent to the ventricles are also most susceptible to hemorrhage. Hemorrhage may be seen on ultrasound, MRI, or CT. Mild hemorrhages involve the germinal matrix adjacent to the ventricles, whereas more severe hemorrhages extend into the ventricles themselves and into the parenchyma of the brain. Hypoxia is known to predispose to periventricular and intraventricular hemorrhage. Approximately one-half of preterm infants with CP are found to have abnormalities on neuroimaging, such as echolucency in the periventricular white matter or ventricular enlargement on cranial ultrasound. In children with CP born at or near term, approximately two-thirds have abnormalities on neuroimaging, including focal infarction, malformations, and periventricular leukomalacia.

Gait Analysis

Gait analysis has become popular in the assessment of movement disorders in children with CP. Accurate documentation of dynamic range of motion may help in planning surgical treatment and assessing the results of orthopaedic operations, and complements but does not replace a good clinical examination. When gait analysis graphs are scrutinized together with information from the clinical examination and slow-motion videotape, better understanding of a patient’s gait can be gained. ^, A detailed discussion of gait analysis can be found in Chapter 5 . The Functional Mobility Scale is a questionnaire that assesses the child’s ambulatory ability at 5 m (within the home), 50 m (short distances), and 500 m (community ambulation) and should be considered in conjunction with gait analysis in surgical decision making. ^,

Kinematics

Certain kinematic patterns are seen in patients with CP. ^a In the hip, scissoring, which is caused by tightness in the adductor musculature and, in part, by weakness of the hip abductors, leads to a narrow base of gait and difficulty advancing the swing-phase limb past the stance-phase limb ( Fig. 31.5 ). In the sagittal plane, increased hip flexion and anterior pelvic tilt may be part of crouch gait as a result of increased tone in the iliopsoas ( Fig. 31.6 ). Increased femoral anteversion may be documented by gait analysis as increased internal rotation of the hips. Asymmetric pelvic rotation may be present, and gait analysis is particularly helpful when the examiner is trying to ascertain whether the abnormal rotation is originating from the pelvis, hips, or tibiae ( Fig. 31.7 ).

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At the knee, sagittal-plane motion is usually abnormal. In patients with tight hamstrings, the knee remains flexed at initial contact and is unable to extend normally during stance phase. In swing phase, spasticity of the rectus femoris may inhibit the patient’s ability to flex the knee and clear the floor ( Fig. 31.8 ). Genu recurvatum during stance phase may be present in response to a tight Achilles tendon, which causes difficulty advancing the tibia forward over the foot.

Ankle kinematics often shows disturbances in plantar flexion, dorsiflexion, and push-off. Plantar flexion on weight acceptance is generally abnormal in patients with equinus contractures. Dorsiflexion during midstance is diminished in the presence of a tight Achilles tendon, and push-off is reduced if the ankle is already plantar-flexed from the equinus. Swing-phase dorsiflexion may be absent as a result of weakness or inactivity of the tibialis anterior and lead to footdrop ( Fig. 31.9 ).

Gait analysis is particularly useful in assessing the cause of toe-walking. It is tempting to attribute all toe-walking to tight Achilles tendons; however, some children walk on their toes in response to crouch above the ankle and have neutral ankle dorsiflexion but increased flexion at the knee and hip. Lengthening of the gastrocnemius or Achilles tendon in these children would result in a calcaneus gait, with persistent crouch at the hip and knee but excessive dorsiflexion at the ankle leading to inefficient push-off.

Electromyography

Spasticity leads to electrical overactivity on electromyography (EMG) during gait, and it seems that the more spastic the child, the greater the EMG signal and the less phasic the muscles in their contraction ( Fig. 31.10 ). Dynamic EMG data collected during gait analysis can be correlated with kinematic and kinetic graphs to gain a fuller understanding of the biomechanics of the child’s gait. For example, normally at initial contact, the ankle plantar-flexes while the anterior tibialis fires on the EMG. Kinetic plots show absorption of power as weight acceptance occurs. In stance phase a child with CP may exhibit early heel rise, seen as plantar flexion on kinematic plots, which correlates with gastrocsoleus overactivity on EMG. We find data from EMG most useful when evaluating a child with a stiff knee in the swing phase for rectus femoris transfer and when assessing a child with an equinovarus foot for tendon transfer (either anterior tibialis or posterior tibialis split transfer).

Kinetics

Kinetics are the forces exerted across joints during gait. Each joint has well-described kinetic patterns, and the reader is referred to work by Gage for descriptions. Two particular forces are clinically interesting: hip pull-off power and ankle push-off power. Hip pull-off power, the force exerted by the iliopsoas and other hip flexors to lift the stance-phase limb off the ground and into the swing phase, is often diminished in patients with CP and leads to decreased energy efficiency ( Fig. 31.11 ). Ankle push-off power, the force exerted by the gastrocsoleus at terminal stance to push the stance-phase limb off the ground, is diminished in patients with equinus or calcaneus gait ( Fig. 31.12 ).

Physical Therapy

Frequently, the first treatment rendered to a child with CP is physical therapy. Yet no controlled studies have confirmed that regular physical therapy improves the outcome of a child with CP. One of the first well-designed studies investigating the effect of physical therapy was performed by Wright and Nicholson in 1973. They found no difference in motor skills or reflexes after 12 months in children who had neurodevelopmental training or physical therapy and those who did not. Other studies followed and again showed no discernible improvement after different forms of therapy. ^{, , ,} In defense of physical therapy, these studies are difficult to carry out because they involve different age groups and children with varying severity of neurologic impairment and usually encompass just a brief period of therapy. However, as Bleck pointed out, “The burden of proof is on the proponents of the treatment. Critics need not prove ineffectiveness but can insist on positive data.” The efficacy of physical therapy can be proved or disproved only with a properly designed, collaborative, multicenter, randomized, controlled trial.

Physical therapy, ranging from the medical model, with the aims of attaining ambulation, range of motion, or transfers, to neurodevelopmental training, sensory integration, and even craniosacral therapy, has been proposed. Electrical stimulation of the muscles has also been used in these patients. ^, Families like physical therapy and attribute gains in their young child’s ability to interaction with the therapist. However, some of these gains are simply the result of neurologic maturation of the child.

Our approach to physical therapy is to establish therapy for monitoring the developmental milestones of very young children, around the age of 2 or 3 years. Therapy is continued if gains are being made in attaining ambulation. School-based programs are used in elementary school and often include adaptive physical education. Postoperative intensive physical therapy is essential to reestablish range of motion and strength after surgical intervention. Strength training of weak muscles has been successful in improving motor function. ^, We also draw on the expertise of physical therapists in assessing orthotic needs and wheelchair seating when appropriate. No evidence supports the continued use of physical therapy for range of motion, particularly in a nonambulatory child. Physical therapists play an important consultative role in making treatment decisions for patients whom they treat on a regular basis and whom we examine on a relatively infrequent basis.

It is common for parents of children with CP to resist discontinuing physical therapy. We believe that goals must be set for therapy and, if progress toward these goals is not being made, either the goals need to be reassessed or therapy should be stopped because it is not useful. Setting measurable functional goals has led to greater success after physical therapy.

In an older child, transitioning from physical therapy to therapeutic recreation is desirable and generally met with enthusiasm by the patient. Adaptive sports or swimming allows the child to participate with peers and affords greater enjoyment than exercises in the therapy gym do. Time in school should be spent on education at this age and not on physical therapy.

Casting

Inhibitive casting has waxed and waned in popularity as a mode of treatment of spasticity in children with CP. It is based on the presence of areas on the feet that are target centers for increased tone at the ankle and, some believe, throughout the lower extremities in certain patients. Usually, short-leg casts are applied with extended toe plates, careful molding of the heel, and metatarsal head control. This has been used by physical therapists and by some physicians. The time spent in casts varies but is generally a minimum of 6 weeks and is followed by the use of orthoses.

In our experience, casting has a limited role in patients with CP. We have used casting in rare cases of very young children (<4 years) with equinus contractures to delay surgical heel cord lengthening. Because equinus recurs after casting, permanent resolution of the equinus is not a goal. Some studies show short-lived improvements in passive and dynamic ankle range of motion following casting, whereas others have reported longer resolution of equinus contractures in children younger than 6 years.

Orthoses

Orthoses can be helpful in improving gait in ambulatory patients with CP. Bracing is best prescribed when specific treatment goals for gait improvement are identified. Ankle-foot orthoses (AFOs) are helpful in positioning the ankle and foot during gait. In young children, dynamic equinus can be improved, with a plantigrade foot position obtained and the tendency for genu recurvatum decreased.

AFOs come in various designs ( Fig. 31.13 ). Solid ankle AFOs are used when minimal dorsiflexion of the ankle is possible. Of the various types, they afford the easiest fit. Solid ankle AFOs also can be used in patients with excessive dorsiflexion and knee flexion; by stabilizing the ankle, extension of the knee is encouraged. Ground reaction AFOs have an anterior shell of plastic across the proximal end of the tibia and are rear entry. The goal of a ground reaction AFO is to provide push-back on the knee during stance phase and help the knee extend. Patients who walk in mild crouch with knee flexion contractures of less than 10 degrees may benefit from this design. Hinged AFOs permit a more natural gait by allowing some dorsiflexion during stance but blocking plantar flexion and therefore eliminating equinus and footdrop. Greater power generation in preswing is seen with hinged AFOs than with solid ankle designs ; however, hinged AFOs are bulkier and break more frequently, and they offer no benefit if the patient does not have passive dorsiflexion of the ankle. If crouch gait is present, a hinged AFO will worsen knee flexion, thereby leading to ankle calcaneus and a less efficient gait. Posterior leaf spring AFOs are fabricated from more pliable polypropylene and have more severe posterior trim lines at the ankle. They are touted as providing a little push-off at terminal stance. They tend to break and may not provide enough hindfoot control in most patients with CP. Gait analysis has shown that posterior leaf spring AFOs function similar to hinged AFOs; that is, they allow some dorsiflexion in stance phase through deformation of the brace, and they control equinus in the swing phase but do not return energy at push-off.

Tone-reducing (or dynamic) AFOs incorporate a molded footplate, termed an inhibitive footplate, and have higher trim lines that extend across the dorsum of the foot. The goal of these orthoses is to apply pressure similar to that of an inhibitive cast and therefore reduce tone throughout the lower extremities. Little scientific evidence supports this design inasmuch as no significant functional changes in gait have been noted with the use of tone-reducing as opposed to standard AFOs. Nonetheless, they remain popular with many families.

Bracing above the knee with knee-ankle-foot orthoses (KAFOs) or hip-knee-ankle-foot orthoses is not generally done in those with CP. The weight and bulk of the braces usually interfere with rather than improve the child’s ability to walk. Short-term use of KAFOs or knee immobilizers after soft tissue surgery for crouch gait can be helpful in retraining children to walk.

Our indications for bracing are

• 1.

  To obtain a plantigrade foot position and reduce genu recurvatum in patients with dynamic equinus

• 2.

  To support the foot in dorsiflexion during the swing phase when footdrop is present

• 3.

  To assist the foot postoperatively while weakness is being treated by physical therapy

• 4.

  To improve mild crouch

We do not advocate the use of AFOs in nonambulatory patients who are able to wear shoes, but we do on occasion prescribe them when footwear is difficult and is improved with orthoses. We also do not use AFOs in a preambulatory young child because they interfere with the child’s ability to crawl and move about the floor.

Some patients walk worse with AFOs than without them. In patients with significant crouch gait, flexion of the knee and hip with the foot supported in an AFO forces the child to either pull up out of the braces or toe-walk despite the orthosis ( Fig. 31.14 ). Toe-walking has not ever been found to be harmful, so it is often better to allow the child to walk on toes brace free or to proceed with surgery when appropriate. Valgus deformities of the hindfeet are often difficult to brace because braces can produce painful calluses and blisters over the prominence of the talar heads. Comfortable footwear without orthoses is preferable for these feet. Finally, as young children with CP become adolescents, they often refuse to wear orthoses for cosmetic reasons. Allowing the patient to make a personal choice in whether to wear a brace is particularly important in this age group.

Oral Medication

Oral pharmacotherapy, including diazepam and baclofen, has been used in an attempt to reduce tone in patients with CP. Side effects include somnolence. Oral tizanidine has been used to relieve spasticity with improved results. Patients with movement disorders such as dystonia or choreiform movements have been treated by various medications, with varying success.

Intrathecal Baclofen

The inability to adequately reduce tone with oral baclofen because of the side effects with large dosages led to trials of intrathecal baclofen. When baclofen is injected into the intrathecal space, small doses can effectively reach the target neural tissue of the spinal cord and produce a greater reduction in tone. Baclofen, a γ-aminobutyric acid agonist, acts at the spinal cord level to impede release of the excitatory neurotransmitters that cause spasticity. After proof of efficacy with test injections of the drug, implantable pumps filled with baclofen are surgically inserted into the anterior abdominal wall and the dose of medication is titrated. Continuous infusion of the medication is delivered by the pump, which requires refilling approximately every 3 months. Studies have shown decreased upper and lower extremity tone and improvements in range of motion with continuous intrathecal baclofen infusion.

Complications occur in approximately 20% of patients. The complications are usually related to catheter dislodgment or fracture, but serious infection occurs in 5%. ^, Overdose of intrathecal baclofen is very rare but serious and can produce somnolence and hypotonia, which leads to respiratory depression requiring mechanical ventilation.

Currently, no strict indications for the use of intrathecal baclofen have been determined, but most pumps are implanted in patients with severe spasticity that interferes with positioning and function of the upper and lower extremities. Pumps are currently being implanted in both nonambulatory and ambulatory patients. Spasticity, as graded by the Ashworth scale, has been shown to decrease 1 year following implantation of intrathecal baclofen pumps regardless of preoperative severity. Caregiver satisfaction in the nonambulatory group is high, with parents noting easier positioning, transfers, and personal care, as well as improved pain control. ^, Pain relief and improved sleep are typically seen within 6 months of pump implantation. Many of these patients still need orthopaedic surgery for hip subluxation and should be monitored for the development of such. Although progressive hip subluxation can occur, significant deterioration in migration percentage is uncommon. Close monitoring for scoliosis is also warranted because rapid progression of deformity has been described in some studies but refuted in others. ^, Several studies comparing progression of scoliosis in patients who had intrathecal baclofen pumps implanted versus a well-matched control group of children with severe CP who were not treated with baclofen found no statistical difference in progression of scoliosis in the treated group. Both groups of patients experienced curve progression, which supports the premise that it is the severity of neurologic involvement and functional disability that predisposes the patient to scoliosis and not the medical management of spasticity ( Fig. 31.15 ). ^{, ,} Additionally, the presence of an intrathecal baclofen pump has not been linked with a higher complication rate following scoliosis surgery.

General Considerations

When evaluating a child with CP for surgical intervention, a few general principles must be kept in mind. Speaking frankly with the family about the goals of surgery and the expected postoperative course is important. Frequently, the family will have unrealistic expectations and believe that surgery will “cure” the child and help him walk normally. It must be explained that CP is a brain disease and that orthopaedic surgery for CP will make the child walk differently, hopefully better, but will not make the child walk “normally.”

Timing of Surgery

Experts recommend combining multiple tendon surgeries and osteotomies into a single surgical event (SEMLS). Rang advised avoiding “birthday surgery,” or hospitalizing the child every year for yet another soft tissue surgery or osteotomy. Aside from avoiding repeated hospitalizations as one joint is released at a time, contractures present at one joint affect the position and movement of the rest of the extremity, so correcting all concomitant contractures and bony malalignment simultaneously during one surgery is important to avoid recurrence or overcorrection of deformity. Because gait changes and matures until approximately 7 years of age, when feasible it is wise to avoid surgery until this time. At this age, multiple levels can be treated simultaneously to optimize the ambulatory skills of the patient, followed by a single aggressive course of physical therapy to maximize the benefits from surgery. This surgical approach has been termed “single-event multilevel surgery.” The literature supports the fact that well-executed surgery addressing all contractures can result in stabilization of patients’ GMFCS level, thereby preserving their function or in some cases resulting in an improved GMFCS level at follow-up (i.e., improving their gait closer toward normal).

In some patients, surgery cannot be delayed until the age of 7 years. Young children with hip subluxation should undergo surgery when the problem is first recognized to improve coverage of the hip. At younger ages, hip surgery is often less extensive and may consist of only soft tissue release, whereas in older children, additional osteotomies of the femur and pelvis are required.

For other children who are nearly ambulatory but whose progress has been halted by contractures in the lower extremities, earlier surgery may allow them additional range of motion to make walking less cumbersome. Adductor release for scissoring and gastrocsoleus surgery with or without hamstring lengthening in these younger children may be indicated. Parents should be forewarned about recurrent contractures requiring additional surgery in the future.

Studies have found that the natural history of gait disturbances in patients with CP is gradual deterioration beginning at 12 years of age. Decreased ankle, knee, and hip sagittal-plane motion, decreased cadence, and slower walking speed have been documented over time in patients who did not undergo intervening surgical procedures. It is common for crouch, contractures, and out-toeing to worsen in the early teen years. Surgery may offer some benefit, but realistic goals must be discussed. Surgery to maintain ambulation can be successful in many children who are GMFCS 3; however, those patients who are GMFCS 4 (therefore nonambulatory) prior to surgery are unlikely to achieve maintenance or restoration of mobility, including even standing transfers, with extensive surgery.

A word of warning regarding tone and its effect on postoperative results is warranted. Best results following SEMLS surgery are seen in patients with pure spasticity. Those patients with dystonia, although preoperatively resembling their spastic counterparts, may experience unpredictable results such as early recurrence or worsening of gait in a subset of cases.

Anesthetic Concerns

Patients with CP experience latex allergy with increased frequency, and for those with suspected latex allergy, a latex-free surgical environment is necessary. Allergy testing is available for latex products. At-risk children are those who have undergone multiple previous operations or who have indwelling latex devices such as gastrostomy tubes or ventriculoperitoneal shunts. ^,

Antiseizure medications may produce alterations in clotting. Increases in bleeding times and decreased platelet counts are known side effects of some antiepileptic agents. Preoperative evaluation of clotting parameters is recommended for major operations such as hip reconstruction or spinal fusion. A routine clotting profile consisting of a prothrombin time and partial thromboplastin time will miss bleeding time abnormalities. Platelet function assays can help identify these bleeding disorders.

Postoperative pain control is difficult in patients undergoing hip reconstruction, spinal surgery, and multilevel tendon surgery. We use short-term inpatient continuous epidural infusions at our hospital and find that if the pain is well controlled, problems with muscle spasm are lessened. Oral medication often needs to include both pain control medications and muscle relaxants such as diazepam.

Postoperative Management

Weakness is a frequent short-term sequela of lower extremity surgery in those with CP. Persistent diminished muscle strength has been documented 1 year following surgery. Plans should be made for frequent postoperative physical therapy beginning shortly after surgery with attention given to muscle strengthening. If at all possible, the patient should be kept ambulatory or weight bearing after the operation. Prolonged time in a wheelchair adds to the overall weakness of the limbs. Patients with osteotomies are the exception to this rule. In these children, weakness may be even more of a problem once casts are discontinued. A few centers have exhibited new enthusiasm for minimally invasive surgery to correct contractures in children with CP. Percutaneous releases with safe intramedullary fixation of rotational osteotomies may result in less loss of strength in the postoperative period. However, because it is imperative that safety be ensured, percutaneous releases are not applicable in all situations.

A trend toward less immobilization after soft tissue surgery has emerged. In our practice, short-leg casts are still used after Achilles tendon lengthening, but knee immobilizers rather than casts are becoming more frequently used after hamstring lengthening, and removable abduction bars are preferable to Petrie casts after adductor release. The goal of soft tissue surgery is greater range of motion, so avoiding overimmobilization and secondary stiffness is logical.

Differential Diagnosis of Equinus

Not all children who walk on their toes have CP. Idiopathic toe-walking, frequently caused by a congenitally short Achilles tendon, is a condition in which otherwise neurologically normal children walk on their toes. Unlike children with CP, these children are not developmentally delayed and learn to walk on time, have normal knee motion during gait, have no neurologic signs of spasticity, and have normal reflexes. Gait studies looking at kinematic and EMG data have attempted to differentiate the two diagnoses on these grounds, ^, but a thorough history and physical examination by an experienced clinician are really all that is needed in most children.

Another condition that produces toe-walking is muscular dystrophy. The condition should be suspected in any young boy who walks on his toes and has a normal birth history. A delay in the age of walking is frequently seen in patients with Duchenne muscular dystrophy, so the developmental history may not differentiate it from CP. Testing for the Gower sign by having the child rise up rapidly from a sitting position on the floor will accentuate the presence of proximal muscle weakness. If the test for the Gower sign is suspicious, laboratory evaluation for serum muscle enzymes (creatine phosphokinase) is indicated.

Clinical Features

Clinical examination of a child with equinus associated with CP reveals an inability to fully dorsiflex the ankle. If the ankle can be passively dorsiflexed with the knee bent to 90 degrees but cannot be dorsiflexed with the knee extended, it is believed that the gastrocnemius is tight but the soleus is not contracted (Silfverskiöld test; Fig. 31.17 ). Many have used this test to determine which type of surgical lengthening to perform. If the ankle has sufficient dorsiflexion on passive range-of-motion examination, the equinus is termed dynamic , and surgical treatment is not usually needed.

Equinus interferes with forward progression of the tibia over the foot during stance phase and therefore shortens stride length. Because the ankle is already plantar-flexed at terminal stance, little push-off power is generated and the gait is less efficient. If the tibialis anterior is unable to lift the foot to neutral during the swing phase, footdrop results, with possible problems in clearing the foot in the swing phase and tripping. Lack of normal swing-phase ankle dorsiflexion leads to forefoot contact on foot strike at the beginning of stance phase. Knee disturbances also result from ankle equinus. Genu recurvatum is seen when the tibia is unable to move forward over the plantigrade foot because of tightness in the gastrocsoleus, so the knee thrusts backward during midstance ( Fig. 31.18 ). The body and femur continue to move forward over the stationary tibia, and an extensor moment is produced at the knee. This aligns the ground reaction force anterior to the knee, thereby reducing demands on the quadriceps and improving the stability of the knee. Likewise, compensatory knee flexion can be seen during stance phase in patients who walk on their toes.

Over time, ankle equinus leads to valgus positioning of the hindfoot and stretching of the plantar arch (midfoot break) . Although the foot may appear plantigrade, the talar head is very prominent in the longitudinal arch and the calcaneus is actually in equinus. Pain and calluses form over the head of the talus ( Fig. 31.19 ). Hallux valgus can develop in response to the valgus positioning of the foot.

Treatment

Surgical treatment of equinus is lengthening of the Achilles tendon, the gastrocnemius/soleus aponeurosis, or selective gastrocnemius fascial recession. Advocates of gastrocnemius recession and aponeurotic lengthening state that these operations preserve or even increase push-off power more than Achilles tendon lengthening does by not involving the soleus muscle or tendon. ^, Immobilization is minimized after gastrocnemius recession, whereas casting is necessary after Achilles tendon lengthening. The risk for overcorrection into a calcaneus gait is negligible. Perry and Hoffer believed that gastrocnemius recession should be performed when a Silfverskiöld test performed under anesthesia is positive and dynamic EMG shows more abnormality of the gastrocnemius than of the soleus during gait.

Those who prefer lengthening of the Achilles tendon recognize a greater rate of recurrence of equinus after gastrocnemius recession, which has been as high as 48% in some studies. They also state that Achilles tendon lengthening may be done percutaneously, unlike gastrocnemius recession. ^, In one comparative gait analysis study, no significant difference was found between patients who had undergone gastrocnemius recession and those who had undergone lengthening of the Achilles tendon. In another study, if equinus was an isolated gait abnormality (i.e., the knee did not lack extension during stance phase), isolated percutaneous Achilles tendon lengthening to a plantigrade position was very successful in improving ankle kinematics and kinetics without resulting in knee abnormalities or a calcaneus gait. A higher risk for calcaneal overcorrection has been noted after percutaneous Achilles tendon lengthening than after Baker gastrocsoleus aponeurotic lengthening. At 9 years of follow-up, a calcaneus gait had developed in only 10% of 44 spastic diplegics treated by gastrocsoleus aponeurotic recession. In contrast, Dietz and colleagues studied 79 children who had undergone Achilles tendon lengthening. At an average of 7 years’ follow-up, they found that a calcaneus gait did not develop in the hemiplegic patients whereas 41% of the diplegic and 50% of the quadriplegic patients did walk with excessive knee flexion and ankle dorsiflexion. Vuillermin and colleagues side with Dietz. They studied the prevalence of crouch in two periods, the first when Achilles tendon lengthening was commonly performed and the second when gastrocnemius recession replaced Achilles tendon lengthening. They found a marked decrease in the development of crouch gait in the second cohort of patients. Confounding factors were the use of gait analysis for preoperative planning and adoption of the SEMLS approach in the group treated with gastrocnemius recession. In longer-term follow-up, the same group has found that 12.5% of children treated with either a gastrocnemius recession or selective gastrocsoleus lengthening did require repeat surgery for equinus, but only 2.5% went on to develop an overcorrected calcaneus gait, strengthening their recommendation for gastrocnemius selective lengthening. The Melbourne group, strong advocates of selective gastrocsoleus lengthening, found that 35% of patients who had conservative surgical treatment of their equinus rather than tendon achilles lengthening (TAL) did have recurrent equinus at midterm follow-up, but that mild equinus was actually favorable in maintaining the knee in extension. Controversy on this subject continues, with surgeons split between those who believe that the adolescent crouch gait is the result of weakness from previous Achilles tendon–lengthening surgery and those who believe it to be due to growth and untreated hamstring spasticity. Increasing knee flexion (crouch gait) has been documented to develop over time in patients who have not previously undergone orthopaedic procedures. Meta-analysis of the existing literature failed to show a scientific preference for one procedure over another, although it was agreed that recurrence was most likely in younger patients and that overcorrection (or talipes calcaneus) was unlikely in hemiplegics when compared with diplegics.

Gastrocnemius Recession

Gastrocnemius recession may be done with the techniques of Strayer, Baker, or Vulpius. In a Vulpius procedure, the aponeurosis of the gastrocsoleus is divided in chevron fashion and the midline fibrous septum of the soleus is transected, but the soleus muscle fibers are not disturbed ( Fig. 31.20 ). The fascia slides on the underlying soleus. ^, The Melbourne group advocates for a transverse cut rather than a chevron cut, with emphasis on division of the midline raphe. The cut in the gastrocnemius is transverse and more proximal in the Strayer procedure, which does not lengthen the soleus whatsoever ( Fig. 31.21 ). In the Baker technique, the gastrocsoleus aponeurosis is cut in tongue-in-groove fashion and dissected free from the underlying soleus muscle. The fascia is allowed to slide on the underlying muscle, thereby increasing the overall length of the muscle, and the four corners of the aponeurosis are sutured in the lengthened position ( Fig. 31.22 ). These surgeries can be divided into groups based on the zone in which lengthening occurs. Zone 1 is from the gastrocnemius origin to the distal end of the medial gastrocnemius. Zone 2 is from the distal end of zone 1 to the end of the soleus muscle belly. Zone 3 represents the Achilles tendon. The Strayer lengthening occurs in zone 1 and the Vulpius and Baker lengthenings in zone 2. ^,

Achilles Tendon Lengthening

Achilles tendon lengthening may be performed by open or percutaneous techniques. In the open technique, a longitudinal incision is made just lateral to the Achilles tendon. The tendon is lengthened in Z-fashion and repaired with stout nonabsorbable suture ( Fig. 31.23 ). The tendon must be repaired with sufficient tension to avoid postoperative calcaneus gait. ^{, ,} The ankle is then immobilized in a short-leg cast for 6 weeks. An open sliding lengthening of the Achilles tendon also may be performed; this procedure does not require suturing of the tendon.

The percutaneous technique may require two or three cuts in the tendon. We prefer the two-cut technique described by White. Just proximal to the calcaneal insertion, a little more than half the tendon is divided medially by inserting a scalpel longitudinally into the center of the tendon, turning the blade out medially, and ballotting the tendon down onto the blade. The lateral half of the tendon is then divided by using a similar maneuver more proximally. The heel is inverted into varus, and the ankle is dorsiflexed to the neutral position (see Plate 31.1 ) . The tendon can be heard lengthening as the ankle is gently manipulated. It is not unusual to hear a pop as the tendon slides and lengthens, although we prefer more gradual and gentle lengthening to prevent overlengthening of the tendon. FLOAT NOT FOUND

It is important to check the integrity of the tendon after percutaneous lengthening. The calf is squeezed while the surgeon observes the ankle. If the ankle plantar-flexes when the calf is squeezed, the tendon can be presumed to be intact within the tendon sheath, and no sutures are needed. Steri-Strips are applied to the two stab wounds, followed by a cast. If no plantar flexion is noted, the tendon may have been completely separated by the lengthening procedure and open suture repair will be needed to reestablish continuity of the tendon. This is a very rare occurrence; usually, the percutaneous technique proceeds without complication. Again, a short-leg cast is applied and worn for 6 weeks, with weight bearing encouraged.

Hoke described a three-cut technique for percutaneous heel cord lengthening. After making one lateral and two medial cuts in the tendon, the ankle is dorsiflexed as the tendon slides on itself and lengthens. Postoperative care is identical to that after the two-cut technique.

Postoperative Care

After either heel cord lengthening or gastrocnemius recession, patients may tend to flex their knees after surgery. This is caused by muscle spasm in the hamstrings and gastrocnemius (which crosses the knee joint). We find that use of a knee immobilizer for the first few days to weeks can help reduce the amount of muscle spasm and prevent the development of a postoperative knee flexion contracture.

After the short-leg cast is removed, an AFO is prescribed postoperatively for most patients. Many children who had footdrop in the swing phase preoperatively will have improved anterior tibialis function in the swing phase postoperatively, while other continue to have footdrop after heel cord lengthening. Patients and families should be forewarned of the potential continued need for orthoses after surgery to support the foot and improve toe clearance in the swing phase. Many younger children benefit from the stability of an AFO postoperatively, whereas in most older children and teens, the goal of heel cord lengthening is to rid them of braces on their feet, so they are reluctant to use an AFO after surgery.

Complications

Complications are rare after heel cord lengthening or gastrocnemius recession. Recurrent equinus is the greatest risk; it occurs in approximately 15% to 35% and correlates strongly with the age of the patient at surgery. Children who undergo heel cord lengthening at 4 years or younger are particularly at risk for recurrence. ^{, ,} It is impossible to know whether it is the greater amount of growth left in younger children after heel cord surgery that leads to the high rate of recurrence, or whether it is preselection of young children with the greatest tone to undergo surgery at an early age after failure of nonoperative treatment that leads to recurrent contracture. In a long-term study by Rattey and colleagues, 26% of patients who had undergone Z-lengthening of the Achilles tendon required repeated lengthening for recurrent equinus at an average follow-up of 10 years. The risk for recurrent contracture was greater in patients with hemiplegia (41%) than in those with diplegia (18%), and in those with more severe preoperative equinus contractures. Grant and associates found that an inability to actively dorsiflex the foot (i.e., lack of selective motor control of the tibialis anterior muscle) preoperatively increased the risk for recurrence. Repeated surgery is possible and common. With repeated lengthening, the Achilles tendon becomes scarred and adherent, so repeated lengthening must usually be done with the open technique. Patients who have undergone gastrocnemius recession have a higher rate of recurrence than do those treated by tendon lengthening.

Calcaneus deformity, defined as excessive dorsiflexion of the ankle during stance phase, may result for two reasons. First, the tendon may simply be overlengthened or may have lost continuity. When performing lengthening, the surgeon must be careful to bring the foot just to neutral. Overstretching of the tendon can lead to excessive length and a calcaneus gait, with poor push-off and a tendency for the development of progressive crouch of the knees.

The second reason that a calcaneus gait may occur after lengthening of the gastrocnemius or Achilles tendon is an unrecognized flexion of the knee during stance phase. If the knee remains crouched and the Achilles tendon becomes longer, the ankle sags into excessive dorsiflexion during stance phase and gait loses efficiency. A meticulous physical examination before surgery in which tone and range of motion of the knee are assessed is critical. If the popliteal angle is increased and the child exhibits excessive knee flexion during stance phase or an inability to straighten the leg as the heel makes contact with the ground, postoperative calcaneus will most likely develop if the knee is not surgically treated at the same time ( Fig. 31.24 ).

The incidence of calcaneus gait as a complication of heel cord lengthening averages approximately 5%. Segal and colleagues found calcaneus on kinematic graphs in 30% of patients. Although this figure seems high in comparison to previous studies, it does highlight the need to treat all levels of deformity during surgery and avoid overlengthening at all cost.

Although most patients in whom a calcaneus gait develops have previously undergone equinus surgery, in a group of patients calcaneus will develop de novo. An adolescent diplegic patient is at greatest risk for calcaneus. Patients who gain weight (as in the adolescent growth spurt) and who have plantar flexor weakness were found on serial gait analysis to be most prone to the development of a calcaneus gait.

Preferred Procedure

In our clinical practice we prefer percutaneous Achilles tendon lengthening as the surgical treatment of fixed equinus contractures and gastrocnemius fascial lengthening when the ankle can be dorsiflexed to nearly neutral with the knee flexed. Postoperative cast immobilization is used for 6 weeks, and AFOs are prescribed on an individual basis. We agree with the philosophy that “a little equinus is better than any calcaneus” and avoid overlengthening. Most important, we thoroughly evaluate the child for other joint involvement, and we typically perform surgery on multiple levels of the lower extremity at the same time (SEMLS). We do see some recurrent contractures with growth, and we reoperate when these contractures interfere with gait. Gastrocnemius fascial lengthening is performed in our center for milder dynamic equinus.

Etiology and Clinical Features

Equinovarus deformity of the foot results from muscle imbalance in which the invertors of the foot, specifically the posterior and anterior tibialis muscles, overpower the evertors (the peroneals). The gastrocnemius contributes equinus to the deformity. Patients walk on the lateral border of the inverted foot, and painful calluses may develop laterally over the fifth metatarsal. The deformity is most prevalent in patients with spastic hemiplegia ( Fig. 31.25 ).

Gait analysis shows an internal foot progression angle as a result of inversion of the foot. Ankle equinus is present, and footdrop may be evident during the swing phase. Pedobarographic assessment demonstrates decreased hindfoot pressure (secondary to equinus) and increased pressure beneath the lateral border of the forefoot and midfoot, specifically the fifth metatarsal ( Fig. 31.26 ).

Treatment

Nonoperative treatment is usually unsuccessful. A supple deformity can be braced, but if the muscles are very spastic, the orthoses can exacerbate the blisters or calluses over the lateral border of the foot. Botulinum toxin injections have been tried, but no published studies have shown long-term efficacy for equinovarus.

Surgery is indicated to improve foot contact and to relieve pain and skin changes. If the foot can be passively corrected with manipulation in the clinic to a neutral position, tendon surgery can be performed. Lengthening procedures and split transfers have been described, and more detail will be provided about these procedures. If the deformity is stiff and the foot cannot be manipulated into a plantigrade position, bone surgery will be necessary. In patients with spastic diplegia and quadriplegia, equinovalgus tends to develop later during childhood and adolescence. Young patients, specifically those younger than 8 years, who are diplegic or quadriplegic are most likely to have unsatisfactory long-term results after surgery for equinovarus. For this reason, nonoperative treatment options should be exhausted in these patients.

Surgical decision making for the soft tissue correction of spastic equinovarus focuses on distinguishing whether it is the anterior tibialis or the posterior tibialis that is the cause of the deformity. The evaluation should start in the clinic with a careful physical examination. The confusion test is helpful in this setting. The patient is asked to flex the hip against resistance while seated, and the ankle is inspected. In most children with CP the anterior tibialis fires while the hip is flexed; this is considered a positive confusion test ( Fig. 31.27 ). However, the reflex has been seen in some children without CP. The examiner should look for the position of the foot as the anterior tibialis fires. If supination of the forefoot is seen, the anterior tibialis is most likely contributing to the equinovarus deformity. If the foot dorsiflexes without supinating, the equinovarus is less likely to improve with surgery on the anterior tibialis.

Next, the examiner feels for spasticity in the posterior tibialis muscle. Passive manipulation of the hindfoot into valgus while feeling the posterior tibialis tendon can help the physician appreciate tightness in the posterior tibialis. The examiner should look at where the varus appears to be located. Hindfoot varus is most probably caused by overpull of the posterior tibialis, whereas forefoot supination is more commonly caused by the anterior tibialis. The examiner should observe for tension in the anterior tibialis and posterior tibialis during gait; the spastic tendon may be visibly taut as the patient walks.

Gait analysis with dynamic EMG can help determine which muscle is acting inappropriately. ^{, ,} Surface electrodes suffice for measuring anterior tibialis activity, but the posterior tibialis is deep, and a fine wire–needle electrode is necessary to measure its signal. The anterior tibialis should be quiet in midstance. Signal from the anterior tibialis throughout stance phase is indicative of overactivity ( Fig. 31.28 ). The posterior tibialis serves to stabilize the foot during stance phase. Early-onset signal and prolongation of the activity during the swing phase indicate an abnormality in control of the posterior tibialis. Nearly one-third of patients with equinovarus will show inappropriate activity of both the anterior and posterior tibialis muscles during gait.

Some patients with equinovarus feet have preexisting footdrop during the swing phase. When this is seen, either in the clinic or during gait analysis, further weakening by anterior tibialis surgery may lead to significant footdrop postoperatively, and an AFO will be needed.

Posterior Tibialis Tendon Lengthening

Surgical options for equinovarus deformity start with lengthening of the posterior tibialis tendon, usually done in conjunction with an Achilles tendon–lengthening procedure in young patients with mild varus in addition to equinus. The tendon may be Z-lengthened distally, or preferably intramuscular lengthening can be performed in the distal third of the calf ( Fig. 31.29 ). The patient is placed in a short-leg cast postoperatively for approximately 6 weeks. Complications consist of recurrence of the deformity and the development of postoperative valgus. The posterior tibialis is weakened by the lengthening, but rebalancing of forces around the foot does not occur to the same extent as with a tendon transfer. Yet in many milder cases this is sufficient to obtain a plantigrade foot.

Split Posterior Tibialis Tendon Transfer

Overcorrection with complete tendon transfers led to the popularization of split tendon transfers in children with CP, one of the most common being that of Green. In this procedure the posterior half of the posterior tibialis tendon is detached from its insertion, split proximally to a level just proximal to the ankle, rerouted posterior to the tibia and fibula, and then woven into the tendon of the peroneus brevis ( Fig. 31.30 ). The remaining posterior tibialis tendon attached to the navicular is then balanced by the lateral half of the transferred tendon, which acts as an evertor. Four incisions were used in the original description of the operation. Usually, an Achilles tendon–lengthening procedure is also required to treat the equinus.

The prerequisite for a successful split posterior tibialis tendon transfer on gait analysis is swing-phase activity seen on dynamic EMG. Yet several authors have reported successful series of split posterior tibialis tendon transfers in which preoperative or postoperative EMG was not performed. ^,

Often, patients can walk without orthoses after this tendon transfer. As with any tendon transfer, the deformity must be passively correctable preoperatively for postoperative correction to be expected. Recurrent varus may be a complication after split posterior tibialis tendon transfer and generally results from inappropriate selection of patients with a deformity that is too rigid. Green stated that overcorrection into valgus has not occurred in their patients, but we have occasionally seen overcorrection in older patients in our outpatient clinics several years after tendon transfer.

Transferring the anterior half of the posterior tibialis tendon anteriorly through the interosseous membrane to the dorsum of the foot is a variation of the classic posterior tendon transfer. It is believed that this split transfer might assist dorsiflexion with less calcaneus deformity than is the case with transfer of the entire tendon because the posterior half of the tendon remains intact. Although studies have shown promising early results, this procedure has yet to be adopted universally. ^,