LUMBOSACRAL AGENESIS

Carlos Cuevas, M.D., Pediatric Orthopaedic Research Fellow

August 23, 1995

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

Lumbosacral agenesis is an uncommon condition characterized by absence of different segments of lumbar spine along with total or partial absence of the sacrum. The motor level can be correlated with the lowest vertebra with pedicles, but sensory level could be above or below, and sometimes asymmetric. Most the time, they have no bladder or bowel control.

ETIOLOGY:

• Unknown
• associated with maternal insulin-dependent diabetes (16% - 50%)
• failure of provocative mechanisms during early embryonic differentiation. Freedman's theory (1950)
• inductive and formative influence of the spinal cord upon the vertebral column. Detwiler's theory (1954)
• genetically determined exaggeration of the pattern of ontogenic cellular death in mesodermal and neural elements of the posterior body regions. Rosenthal (1968)
• inheritable genetic factors. Pouzet (1938)

CLINICAL FINDINGS:

Appearance:

Patient with multiple abnormalities with short trunk correlated with the degree of lumbar agenesis; marked atrophy of the buttocks showing gluteal dimples with short intergluteal fold, and horizontal anus. Characteristically severe atrophy of the lower limbs with an appearance similar to that of distal arthrogryposis; the lower extremities are in flexion, abduction, and external rotation contracture at the level of the hips, and usually there is a severe flexion contracture of the knees giving the classic Buddha-like position often described. However, the appearance of the patient is directly correlated with the degree of lumbosacral spinal involvement.

GENERAL FINDINGS:

• hydrocephalus: frequent when associated with myelomengocele
• myelomeningocele: occurs in 30 - 40%
• urinary tract: horseshoe kidney, solitary kidney, kidney malformations, reflex and no bladder control are common
• inguinal hernia, imperforate anus, rectovaginal fistula, anal malformation, Crohn's disease, no bowel control
• heart abnormalities are not common, but have been described

SPINE FINDINGS:

• cervical spine is commonly involved. Multiple vertebral fusions, C2 - C3 fusion, odontoid abnormalities, odontoid absence, and ball and socket occiput-atlanto joint with or without instability
• segmentation or formation defects are common findings in vertebrae and ribs of patients with sacral agenesis
• scoliosis is better correlated with the presence of thoracic or thoracolumbar vertebrae abnormalities (i.e. hemivertebra) than the lumbosacral defect. However, scoliosis may occur when an asymmetrical spino-pelvic "joint" is seen, or a part of the sacrum remains in the pelvis
• kyphosis is common finding, it's correlated with high level lumbosacral agenesis and spino-pelvic instability. Kyphosis is often severe, reducing the abdominal capacity and producing rib-pelvic "pseudo-joint"

LOWER EXTREMITIES:

• frequently, hips have a flexion, abduction and external rotation contracture. Sometimes, the hips are dislocated secondary to pelvic obliquity and/or the acetabula reorientation
• commonly, the knees have a flexion contracture, and sometimes this is severe
• feet: plano-valgus, calcaneo-valgus, vertical tali, and tarsal and metatarsal synostosis, are frequent findings in patients with lumbosacral agenesis.

CLASSIFICATION:

Renshaw (1978) classified sacral agenesis in four types:

• Type I: total or partial unilateral sacral agenesis
• Type II: partial sacral agenesis with a partial but bilaterally symmetrical defect and a stable articulation between the ilia and a normal or hypoplastic first sacral vertebra (most common).
• Type III: variable lumbar and total sacral agenesis with the ilia articulating with the sides of the lowest vertebra present
• Type IV: variable lumbar and a total sacral agenesis, the caudal end-plate of the lowest vertebra resting above either fused ilia or an iliac amphiarthrosis

TREATMENT:

Extensive investigation of the whole spine; the genitourinary, cardiovascular, and gastrointestinal tracts should be done in the initial approach of patients with lumbosacral agenesis.

Three major trends of management have been described:

• Ablation of the lower extremities (subtrochanteric level or knee disarticulation) plus prosthetic fitting (Russel, 1963; Aiken et al, 1967; Tachdjian, 1990)
• Spinal pelvic fusion: "increase abdominal capacity, and protect viscera from unphysiologic compression" (Winter, 1991, Renshaw, 1978)
• Correction of the inferior limb deformities and orthotic fitting; based on the fact that most patients have preserved protective sensation and proprioception of the lower extremities. "Spinal-pelvic motion is helpful to maintain the sitting position in patients with fixed flexion contracture of the hips". (Banta, 1969; Andrish, Kalamchi, and MacEwen, 1979)

HIP:

• Early open reduction may be indicated; some times secondary procedures including varus derotational osteotomy with or without pelvic osteotomy may be required
• In a fixed flexion contraction deformity of the hip, extension proximal femoral osteotomy may be indicated.

KNEE:

• Posterior release and sometimes distal femoral flexion osteotomies may be indicated to increase the extension of the knees (Recurrence of the deformity in the absence of quadriceps motion may occur).

FOOT:

• Plantigrade foot is the goal of the treatment; usually surgical releases in early age are indicated and orthotic support is needed to avoid recurrence of the deformities, and permit adequate weight-bearing in ambulatory patients.

REFERENCE:

1. Andrish J., Kalamchi A, MacEwen, G.D. Sacral Agenesis: A Clinical Evaluation of the Management, heredity and associated anomalies. Clin. Orthop. 139:52-57,1979

2. Banta J.V., Nichols O. Sacral Agenesis. J. Bone Joint Surg. 51:693-703,1969

3. Dumont C.E., Damsin J.P., Forlin E., Carlioz H. Lumbosacral Agenesis. Spine 18:1229-1235,1993

4. Renshaw T.S. Sacral Agenesis. The Pediatric Spine - Principles and Practice. 1:2214,1994,

Raven Press, New York

5. Phillips W.A. Sacral Agenesis. Spine - Principles and Practice. 1:2214,1994, Raven Press, New York

6. Jay Kumar S. Personal Communication. July 1995

7. Phillips W.A., Cooperman D.R., Linquist R.C., Sullivan R.C., Millar E.A. Orthopaedic Management of Lumbosacral Agenesis. Long Term Follow Up. J. Bone Joint Surg. 64A:1282-1294,1982