Lower Extremity Surgery in Children With Cerebral Palsy

Nirav K. Pandya, MD

Henry G. Chambers, MD

Dr. Pandya or an immediate family member serves as a board member, owner, officer, or committee member of the Pediatric Orthopaedic Society of North America. Dr. Chambers or an immediate family member serves as a paid consultant to or is an employee of Allergan and Orthopediatrics and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons, the American Academy for Cerebral Palsy and Developmental Medicine, and the Pediatric Orthopaedic Society of North America.

INTRODUCTION

Cerebral palsy (CP) is an abnormality of motor function that results from an insult to the brain during early development. The musculoskeletal manifestations of this disorder are progressive. Surgical management of the lower extremity in these patients requires a thorough understanding of the indications for these procedures and how the procedures will affect the functional status of these patients. Surgery should be delayed as long as possible (until the patient is older than 6 years), and spasticity management should be used as an adjunct to surgery. When multiple deformities exist, single-stage surgery is recommended to prevent decompensation from unbalanced correction.

Traditionally, the patient with CP is classified based on the Gross Motor Function Classification System (GMFCS),¹ which assigns patients with CP to one of five functional groups based on self-initiated ambulatory function and postural control (Figure 1). The Functional Mobility Scale (FMS)² also rates ambulatory ability at 5, 50, and 500 m, giving a more dynamic assessment of a patient’s mobility (Figure 2).

The combination of these two scales can help to define quickly and reproducibly the ambulatory status of patients with CP. This is important because the type of surgery recommended for the patient with CP depends largely on whether the patient is ambulatory (GMFCS levels I through III) or nonambulatory (levels IV and V). Whereas the goals of surgery in the ambulatory patient are to improve or maintain the patient’s ability to walk, nonambulatory surgery is performed to increase comfort, positioning, sitting balance, and posture. Using ambulatory procedures in a nonambulatory child (and vice versa) may lead to significant loss of function.

Ambulatory Patients

The clinician must have a thorough understanding of gait analysis when evaluating the ambulatory patient with CP. This can be performed via observational (in the clinic) or instrumented (in the laboratory) gait analysis. The utilization of either of these techniques allows the clinician to understand how the patient’s disease process affects their dynamic function rather than their static examination on the table. It can be used to not only identify gait abnormality but also set treatment goals and measure treatment effect. Whereas observational analysis can be used to assess alignment, coordination, and proprioception, instrumented analysis (particularly 3D) can quantify joint kinematic and kinetics.

Once the appropriate gait abnormality is identified, the correct surgical procedure can be chosen. Common gait abnormalities seen in the ambulatory patient with CP include scissoring gait (excessive hip adduction), crouched gait (excessive hip flexion, knee flexion, and ankle dorsiflexion), jump gait (excessive hip flexion, knee flexion, and ankle plantar flexion), stiff-knee gait (swing-phase knee stiffness due to an overactive rectus femoris muscle), and recurvatum gait (knee hyperextension due to equinus contracture).

At the level of the foot, ambulatory patients also may have a pure ankle equinus deformity (excessive ankle plantar flexion), equinovarus deformity (excessive ankle plantar flexion with an overactive tibialis posterior or tibialis anterior), or pes planovalgus deformity (overactive peroneals and/or bony deformity). The surgical options for the components of the gait abnormalities mentioned above are shown in Table 1.

The ambulatory patient with CP also may have rotational abnormalities (lever-arm disease) at the level of the hip and knee (eg, increased femoral anteversion, internal/external tibial torsion) that may require corrective surgery. Unlike the typically developing patient, who may be able to compensate for these rotational abnormalities, the patient with CP requires correction via proximal or distal femoral osteotomies and/or tibial derotational osteotomies to preserve ambulatory function.

Therefore, before determining the appropriate surgical procedure in an ambulatory patient with CP, the clinician must consider the following: (1) the gait abnormality present, (2) the soft-tissue and bone components that may
be causing the ambulatory dysfunction, (3) the appropriate procedures to correct the gait abnormalities based on the anatomic contractures/imbalances leading to them, and (4) that rotational abnormalities need to be corrected more aggressively in the patient with CP than in the nonneuromuscularly impaired patient.

FIGURE 1 Illustration of the Gross Motor Function Classification System (GMFCS) for cerebral palsy. A, Levels I through III (ambulatory). B, Levels IV and V (nonambulatory). E & R = expanded and revised. (© Kerr Graham, Bill Reid and Adrienne Harvey, The Royal Children’s Hospital, Melbourne, Australia. Data from Palisano R, Rosenbaum P, Walter S, Russell D, Wood E, Galuppi B: Development and reliability of a system to classify gross motor function in children with cerebral palsy. Dev Med Child Neurol 1997 39[4]:214-223 and data from CanChild Centre for Childhood Disability Research Institute for Applied Health Sciences, Ontario, Canada.)

Nonambulatory Patients

Nonambulatory patients with CP also can undergo procedures around the hip, knee, and ankle; however, the options are not as extensive as those for the ambulatory patient. In the hip, spastic subluxation or dislocation with severe acetabular dysplasia can be present. This can lead to difficulty in sitting and transfers and can exacerbate scoliosis. A combined adductor, psoas, and proximal hamstring lengthening, open reduction and capsulorrhaphy of the hip, pericapsular pelvic osteotomy, and femoral shortening varus derotation osteotomy (particularly in patients with increased valgus and femoral anteversion) can manage this problem. In the knee, severe flexion contractures that interfere with sitting and hygiene can be corrected with distal hamstring lengthening. Finally, deformities of the foot in nonambulatory patients can be corrected as in ambulatory patients (Table 1), resulting in a foot that can rest plantigrade on a wheelchair platform.

FIGURE 2 Illustration of the Functional Mobility Scale for cerebral palsy. (© Kerr Graham, Bill Reid and Adrienne Harvey, The Royal Children’s Hospital, Melbourne, Australia.)

SOFT-TISSUE LENGTHENING PROCEDURES

Adductor Lengthening

Preoperative Imaging

No preoperative imaging is required unless the adductor tenotomy is part of a larger procedure for spastic hip subluxation/dislocation. In that case, imaging includes AP and frog-leg lateral views of the pelvis and bilateral hips and possibly CT with three-dimensional reconstructions.

Surgical Technique

For this procedure, the patient is positioned supine. The perineum is draped free. A transverse incision is made over the palpably tight adductor longus tendon, one fingerbreadth distal to the groin crease. The fascia overlying the adductor longus tendon should be opened (Figure 3, A), and a right-angle clamp should be used to isolate the adductor longus tendon, passing the clamp from medial to lateral. The tendon should be cut as proximal to its attachment to the pelvis as possible with an electrocautery. After the adductor longus tendon has been transected, the surgeon should encounter the anterior branch of the obturator nerve overlying the adductor brevis tendon inferiorly, the pectineus muscle superiorly, and the gracilis muscle medially (Figure 3, B). If an intraoperative test confirms that abduction of the leg is hindered more with the leg in extension than in flexion, the gracilis muscle also can be isolated with a right-angle clamp and transected (Figure 3, C). If further abduction is desired, the adductor brevis can be isolated with a right-angle clamp and transected as well. The goal should be to obtain 45° of abduction. Lying below
the adductor brevis, the large adductor magnus and its overlying posterior branch of the obturator nerve must be preserved to maintain the ability to adduct. After all tenotomies are performed, hemostasis should be obtained to prevent hematoma formation. The wound should be closed in layers.

TABLE 1 Typical Abnormalities and Potential Surgical Options in Ambulatory Patients With Cerebral Palsy

Abnormality	Potential Surgical Treatments
Hip adduction contracture	Adductor tenotomy
Hip flexion contracture	Psoas release at pelvic brim
Knee flexion contracture	Distal hamstring lengthening
Knee flexion contracture	Distal femoral extension osteotomy with patellar tendon advancement
Knee recurvatum	Ankle plantar flexor lengthening
Stiff-knee gait	Rectus femoris transfer
Equinus contracture	Ankle plantar flexor lengthening
Equinovarus deformity of the foot	Posterior tibialis lengthening, split posterior tibial tendon transfer, split anterior tibialis transfer, ankle plantar flexor lengthening
Pes planovalgus deformity	Peroneus brevis lengthening, calcaneal lengthening osteotomy (± cuneiform osteotomy), calcaneal sliding osteotomy (± cuboid and cuneiform osteotomy), subtalar arthrodesis, triple arthrodesis

FIGURE 3 Intraoperative photographs demonstrate the surgical technique for adductor lengthening. A, The adductor longus tendon is shown with its overlying fascia identified before tenotomy. B, The anterior branch of the obturator nerve is identified with a hemostat. C, The gracilis tendon is identified before tenotomy. (Reproduced with permission from Sawyer JR: Cerebral palsy, in Canale ST, Beaty JH, eds: Campbell’s Operative Orthopaedics, ed 11. Philadelphia, PA, Mosby/Elsevier, 2007, pp 1333-1399.)

Postoperative Care and Rehabilitation

Postoperatively, the patient is placed in Petrie casts with a bar between the legs or into an abduction brace, which is worn full time for 4 weeks and then worn at night for 6 months.

Pearl

The initial incision should not extend too far laterally beyond the lateral border of the adductor longus tendon to avoid encountering the femoral neurovascular bundle.

Distal Hamstring Lengthening

Surgical Technique

The patient is positioned supine if this procedure is performed with other surgeries or prone if performed as an isolated procedure. If the patient is supine, medial and lateral incisions can be made; if the patient is prone, a single midline incision is used. The incision(s) should begin 1 to 2 cm proximal to the knee joint and extend proximally for 5 to 7 cm (Figure 4, A). For the two-incision technique, the incisions should be placed slightly anterior to the hamstring tendons, which should be palpably tight
with the leg extended. Dissection on the medial side of the leg should be taken posterior to the sartorius muscle (the most superficial muscle) to open the fascia overlying the gracilis muscle. The tendon overlying the gracilis muscle belly should be cut with a knife or electrocautery. Deep to the gracilis, the semitendinosus tendon should be encountered and the fascia over the muscle opened, followed by cutting of the tendon overlying the muscle belly or a Z-lengthening if additional length is required. The deepest, broadest muscle that will be encountered is the semimembranosus muscle; its fascia should be opened as well, followed by transection of the tendon overlying the muscle belly. Two cuts can be made in the tendon if necessary (Figure 4, B). After all tendons have been cut, straight-leg raising can be performed to provide an additional amount of lengthening. Forceful extension should not be performed, to avoid sciatic nerve damage.

FIGURE 4 Illustrations demonstrate surgical technique for distal hamstring lengthening using a single midline incision. A, The approach. B, Transection of the tendon overlying the semimembranosus muscle belly (in forceps). Two cuts have been made in the muscle belly to gain additional length.

Lengthening of the lateral hamstrings is rarely indicated; however, if necessary, attention is turned to the lateral incision, if a two-incision technique is used, or to the lateral aspect of the incision, if a single midline incision is used. For the two-incision approach, the incision is made anterior to the biceps tendon to avoid the peroneal nerve. Dissection is carried down to the level of the fascia overlying the biceps tendon that is opened, and the tendon overlying the muscle belly is transected. Both wounds can now be closed in a layered fashion.

Postoperative Care and Rehabilitation

A knee immobilizer or knee range of motion brace should be placed in the amount of flexion that can be achieved comfortably without stretching the sciatic nerve. The patient is allowed to bear weight as tolerated with the cast. The immobilizer is kept in place for 4 weeks, and then the patient is allowed to return to a stretching program.

Pearl

The sciatic nerve should be monitored carefully postoperatively.

Lengthening of the Gastrocnemius-Soleus

Surgical Technique

The patient is positioned supine. A posteromedial incision is made over the middle third of the leg, posterior to the calf muscles. Blunt dissection should be used to develop the plane above the gastrocnemius and soleus muscles. The fascia overlying the gastrocnemius and soleus muscles is opened, and the tendons overlying these muscles are released from medial to lateral under direct visualization, with the foot held in maximal dorsiflexion (Figure 5). Care should be taken to preserve the muscle underlying the tendons. The sural nerve should be identified. Further dorsiflexion can be performed after the release, and spreading of the underlying muscle should be visualized. The wound is closed in a layered fashion.

Postoperative Care and Rehabilitation

Patients are placed in a short leg weight-bearing cast with the foot in a neutral position for 4 to 6 weeks. The patients then may be transitioned to an ankle-foot orthosis for maintenance of correction, based on disease severity.

Pearls

Overaggressive dorsiflexion of the foot after release should be avoided to prevent a complete tear of the Achilles tendon.
If an associated peroneus brevis lengthening is being performed, the incision also can be made laterally.
Posterior tibialis lengthening also can be performed through the medial incision.

Peroneus Brevis Lengthening

Surgical Technique

The patient is positioned supine. A posterolateral incision is made over the distal one-third of the leg. Care is taken to identify and protect the superficial peroneal nerve. The peroneus longus tendon is identified, and the fascia overlying the tendon is opened. The peroneus longus tendon is retracted inferiorly, and the fascia overlying the peroneus brevis tendon is opened. The tendon overlying the muscle belly is transected, and foot is placed in inversion to provide further lengthening. The wound is closed in a layered fashion.

Postoperative Care and Rehabilitation

Because this procedure rarely is performed in isolation, postoperative care should be dictated by the larger procedure that is performed.

Pearl

If gastrocnemius-soleus lengthening is performed concomitantly, it can be performed within the same incision before the peroneus brevis lengthening.

Posterior Tibial Tendon Lengthening

Surgical Technique

The patient is positioned supine, with a bump under the hip. An approximately 3-cm incision over the medial border of the tibia at the junction of the middle and distal one-third of the leg is made (Figure 6, A). The posterior border of the tibia is palpated, and dissection is carried down to the deep posterior compartment of the leg, the fascia of which is opened. The flexor digitorum longus muscle, which lies medial to the posterior tibialis tendon at this level, is encountered. The flexor digitorum longus tendon is retracted posteriorly, and the fascia overlying the posterior tibial tendon is encountered and opened. The tendon overlying the posterior tibial muscle belly should then be transected with a knife (Figure 6, B). The wound is closed in a layered fashion.

Postoperative Care and Rehabilitation

Because this procedure rarely is performed in isolation, postoperative care should be dictated by the larger procedure that is performed.

FIGURE 6 Illustrations demonstrate the surgical technique for posterior tibial tendon lengthening. A, The incision (dashed line). B, Transection of the tendon overlying the muscle belly.

Pearl

When opening the deep posterior compartment, the flexor digitorum longus muscle is first encountered. An error can be made if this muscle is assumed to be the posterior tibial tendon.

Psoas Release at the Pelvic Brim