Genetically transmitted skeletal malformation
characterized by hypoplasia or aplasia of the patella, epiphyseal, and
hip/pelvic girdle anomalies.
Coxopodo Patellar Syndrome; Small Patella Syndrome; SPS;
Autosomal dominant with variable penetrance
(majority of patients); sporadic dominant mutation (rare).
Small patella syndrome (SPS) is a bone dysplasia
affecting predominantly the pelvis, knees, and feet. The patellae are either
small or absent; when present they may be laterally placed, resulting in
recurrent dislocation of the patella.
Based on morphologic and radiologic
appearances: increased space between the first and second toes, shortening
and clinodactyly of the fourth and fifth toes, and flat feet are the
findings in some patients. Absent or hypoplastic patellae (laterally placed
or dislocated) are typical. Most patients have pelvic abnormalities: absent
ischial ossification at the ischiopubic synchondrosis, infra-acetabular
axe-cut notch, high iliac angles, large femoral heads with narrowed femoral
necks, coxa valga or vara, and hypoplastic lesser trochanters. Patients may
complain of femoropatellar pain syndrome, but symptoms referable to the
pelvic girdle are very rare. Two sporadic cases of SPS associated with
facial dysmorphic features have been reported: one patient had a flattened
nose with prominent forehead, and the other had micrognathia, high-arched
palate, and subglottic stenosis with generalized tracheomalacia; she also
had bilateral talipes equinovarus (clubfeet). These facial and airway
abnormalities likely are not part of the SPS itself. The differential
diagnosis of SPS is either an isolated finding of displaced patellae or the
“nail-patella syndrome” (iliac horns, elbow abnormalities, nail
No specific precautions with this
Obtain a “skeletal survey”: SPS
affects mainly pelvis, knees, and feet, but other parts of the skeleton may
be abnormal. One case of minor spine involvement (mild thoracic scoliosis
with normal pulmonary function, and lumbar hyperlordosis) reported. These
findings should not affect anesthetic management unless scoliosis becomes
significant enough to compromise breathing (pulmonary function tests are
required). No anesthetic considerations specific to SPS.
No specific pharmacological
Familial Recurrent Dislocation of the Patella (Congenital Dislocation of the
Patella): Lateral displacement of the patella as a result of pull of the
quadriceps muscle while the tibial tubercle abnormally lies lateral to the long
axis of the femur. When the knee is flexed, the patella slides distally and is
engaged by the trochlear groove in the femur.
Nail-Patella Syndrome: Autosomal dominant polymalformative
syndrome characterized by nail dysplasia, patellar aplasia-hypoplasia,
multiple joint dysplasias (elbows, iliac horns), and nephropathy.
Bongers Ernie MHF, Van Bokhoven H, Van Thienen MN, et al: The small
patella syndrome: Description of five cases from three families and
examination of possible allelism with familial patella aplasia-hypoplasia
and nail-patella syndrome. J Med Genet
Kozlowski K, Nelson J: Small patella syndrome. Am J Med Genet