Myelomeningocele and spinal dysfunctions in pediatric age: surgical treatment of the deformities of the lower limbs

Myelomeningocele and spinal dysfunctions in pediatric age: surgical treatment of the deformities of the lower limbs



Spinal dysoxysms (from the Greek dys = bad, raphe = closure, suture) include a large group of pathologies with variable severity (spina bifida occulta, diastematomelia, lipomeningocele, meningocele, myelomeningocele, caudal regression syndrome) in which there is an anomaly of development involving the spine and the spinal cord (for an alteration of the closure of the "neural tube").

This results in very different pathological patterns, from milder forms of occult spina bifida (lack of fusion of one or more vertebral arcs, which can be an occasional finding without pathological significance) to forms of caudal regression syndrome (sacral and lumbosacral agenesis) characterized absence of variable portions of the lumbar and sacral (and of the corresponding nerve structures), up to serious forms of myelomeningocele (MMC) in which a serious involvement of the nervous structures is already associated with the birth (motor paralysis, sensitivity disorders, sphincter disorders , hydrocephalus, etc.).

A common feature of these conditions is the close connection between orthopedic problems and neurological problems: the latter must therefore be carefully considered in the treatment (physiotherapeutic, orthesis, surgical) of these patients.
Medullary anchorage ("tethered cord")

If in the most severe forms (MMC, caudal regression) the picture is already established at birth and requires the early activation of a multidisciplinary team, in other forms (lipomeningocele, diastematomelia, etc.) the patient can be completely asymptomatic at birth and in the first years of life, and can present itself to the observation of the orthopedist during the growth, for the manifestation of progressive musculoskeletal changes.

Fig. 1 - MRI of an 8-year-old girl with diastematomelia at the L1Fig level. 1 - MRI of an 8-year-old girl with diastematomelia at the L1 level

In these conditions, in fact, the basic malformation causes with growth a progressive disorder on the nervous structures (spinal cord, nerve roots) that causes peripheral neurological deficits and progressive deformations of the lower limbs.
The mechanism by which this occurs is generally an anchoring of the cord ("tethered cord") to the surrounding structures at the level of the malformation, which leads with the patient's growth, to a progressive stretching of the marrow itself.

The most common orthopedic manifestation of these conditions is the equine-hollow-varus foot, but other manifestations are possible, such as equine foot or lower back pain with possible irradiation to the lower limbs.

Fig. 2 - Progressive equino-varus-supinate foot, secondary to medullary lipomaFig. 2 - Progressive equino-varus-supinate foot, secondary to medullary lipoma

The task of orthopedics is to suspect that these deformities are secondary to spinal dysraphism and initiate investigations (neuroelectric examination, MRI, etc.) towards these pathologies.

Sometimes the presence of skin changes (angiomas, skin dimples, tufts of hairs, lipomatous masses, etc.) at the level of the midline of the lumbar or lumbosacral region can help in suspecting these diseases. But it is especially important to perform a careful clinical evaluation with a thorough neurological examination, which should highlight the neurological deficits present (muscle weakness, sensitivity changes, sphincter disorders).

The patient will then be directed towards a neurosurgical evaluation, for an eventual release of nerve structures.
This process is fundamental: if the orthopedic is limited to correcting the present deformity, without first having entrusted the patient to a neurosurgical evaluation (and without having removed the causes that determine the deformity), he exposes himself and the patient to a high risk of rapid recurrence of the deformity.
myelomeningocele

The treatment of patients with MMC is very complex and involves, as already mentioned, a multidisciplinary work (neurosurgeon, urologist, general surgeon, physiatrist, physiotherapist, orthopedist, orthopedic technician, psychologist, occupational therapist, etc.).

The physiatric and orthotic evaluation of these children is carried out in collaboration with the Physical and Rehabilitative Medicine Unit of the Rizzoli Orthopedic Institute.


A detailed examination of the pathogenic, clinical and therapeutic aspects of this condition is beyond the pretension of this card.

Given the wide variability of neurological involvement of these patients (thoracic levels, upper lumbar levels, lower lumbar levels, sacral levels, associated Arnold-Chiari type malformations, associated hydrocephalus, medullary anchorage during growth, etc.), as well as deformities of lower limbs already present at birth, there is a wide spectrum of musculoskeletal problems that can be found in the individual patient affected by MMC.

We limit ourselves here to summarize the main problems of lower limbs that may require surgical treatment and to list the surgical procedures that are most frequently performed in the Division of Pediatric Orthopedics for these issues.
Deformities of the feet and ankles
Talism (such feet)

This deformity, which is quite common in MMC patients, may be present at birth, but generally occurs later, due to muscular imbalance (active anterior tibialis, defective plantar flexors). Anterior release surgery may be necessary, associated with anterior tibial transfer (and possibly also other tendons) on the calcaneus, or in patients with an increase in growth, an arthrodesis of the ankle joint.
Equine-varus-supine feet (or congenital clubfoot, PTC)

Feet that have such congenital deformity are generally more rigid, more resistant to treatment, and at greater risk of recurrence than idiopathic PTC (see card on clubfoot). It is possible to make an initial treatment attempt with gypsum according to the Ponseti method, while taking into account the increased risk of plaster decubitus (related to impaired sensitivity).
Alternatively, a posterior and medial release intervention of the soft parts is necessary (Codivilla's intervention).
Equine feet

In case of deformity in pure equinism, which do not respond to conservative treatment (guardians, physiotherapy), corrective interventions are indicated (Achilles tendon lengthening, posterior release).
Feet reflexes.

It is a complex deformity of the foot already present at birth that in most cases requires corrective intervention on the soft parts (posterior, medial, plantar and lateral release).
Valgism of the foot and ankle

These are quite common problems in patients with MMC, which can cause problems with the use of orthotics and braces. The orthopedic is called to distinguish the seat of the deformity (valgus of ankle or valgism at the level of the foot or both).
In the case of ankle deformity, surgical options include: distal tibia corrective osteotomy and asymmetric epifisiodesis of the distal tibia (ie progressive deformity correction, in growth patients).
In case of localized deformity in the foot (subtalar joint), the orthopedic will have to evaluate the most suitable surgical procedure among the various options (arthrodesis, arthritis, osteotomies, etc.) taking into account the specific characteristics of the patients with MMC.
Deformity of the knees
Contracts in flexion

Flexural (ischiocrural) flexural muscles may be required if progressive deformities of the flexion knees occur that interfere with walking.
Contracts in extension

Such deformities rarely require surgical treatment (elongation of the quadriceps).
Deformity of the hips
Hap contracting

Interventions of release of the soft parts are indicated in case of contractures of the hips in abduction-external rotation or in flexion, which interfere with the function (static, walking, use of guardians), only after adequate clinical evaluation.
Subluxation and dislocation


This is a very common problem in children with MMC: it is generally the imbalance between functioning flexor / adductor muscles and hypovalic extensors / abductors that causes the progressive alteration of the relationships between the femur and the acetabulum up to complete dislocation.

Fig. 3 - Dislocation of the left hip in a patient with myelomeningoceleFig. 3 - Left hip dislocation in a patient with myelomeningoceleThis treatment requires an accurate functional evaluation (evaluation of muscular function, neurological level, pelvic obliquity, spine alignment, walking ability, etc.) and not a simple evaluation radiographic.

The fundamental question concerns the opportunity or not to proceed with complex interventions for the reduction of dislocations and joint reconstruction.
In fact we must consider on one hand the possible advantages of a reduction (in particular, stabilize the joint, avoid differences in length between the two limbs, prevent the obliquity of the pelvis and scoliosis) but on the other the high rate of complications which may be associated with treatment (risk of rigidity, fractures, ossifications at the time of surgery, high risk of relapse of dislocation after treatment). However, the main objective remains the maintenance of the flexibility of the joint and the resolution of contractures that can cause obliquity of the pelvis itself.

In the event that, as a result of functional assessment, the goal is to reduce dislocation, the patient undergoes a surgical program that provides (in a single surgical time or in several surgical times):

    bloody reduction of the hip;
    femoral osteotomy;
    acetabular osteotomy;
    muscle-tendon release interventions (iliopsoas, adductors) and tendon transfer to balance the muscular imbalance (transfer of iliopsoas according to Sharrard or according to Mustard, transfer of the external oblique muscle from the musculature of the abdominal wall on the great trocantere).

These are complex interventions, which should only be carried out in centers of reference with documented experience (and the Rizzoli Orthopedic Institute is one of these).
Torsional deformities of the lower limbs

Torsional (rotatory) deformities of the lower limbs (especially the external tibial torsion) are quite common in walking patients with MMC and may cause disturbances in the use of guardians and walking.

After accurate clinical evaluation and possible CT reconstruction of the torsion axes, a derotative osteotomy intervention can be indicated.