Skip to
  1. Homepage
  2. Rare diseases
  3. Search
Simple search

Simple search

(*) mandatory field


Other search option(s)

Coxopodopatellar syndrome

Synonym(s) Ischiopatellar dysplasia
Scott-Taor syndrome
Small patella syndrome
Prevalence <1 / 1 000 000
Inheritance Autosomal dominant
Age of onset Infancy
  • Q74.1
  • C1840061
  • C1868581
MeSH -
MedDRA -


Disease definition

Small patella syndrome (SPS) is a very rare benign bone dysplasia affecting skeletal structures of the lower limb and the pelvis.


Less that 50 patients have been reported worldwide.

Clinical description

The main clinical features include patellar aplasia or hypoplasia, associated with absent, delayed or irregular ossification of the ischiopubic junctions and/or the infra-acetabular axe-cut notches. Additional features found in the majority of reported patients include femur and foot anomalies (a wide gap between the first and second toes, short fourth and fifth rays of the feet, and pes planus). Craniofacial anomalies (micrognathia, cleft palate, flattened nose and prominent forehead) have been reported occasionally. Intrafamilial variability of the patellar, pelvic and foot anomalies has been described. Signs and symptoms vary from pain resulting from gonarthrosis in elderly subjects to recurrent luxations from infancy, knee pain, and inability to run and ride a bicycle. However, some cases are asymptomatic.


SPS is caused by mutations in the human TBX4 gene (chromosome 17q22). TBX4 mutations account for familial cases with a distinctive facial appearance and those without facial features. At present, there is no evidence for a genotype-phenotype correlation.

Diagnostic methods

Diagnosis is clinical and radiographical.

Differential diagnosis

SPS should be recognized and differentiated from disorders with aplastic or hypoplastic patellae, such as isolated familial patella aplasia-hypoplasia (PTLAH) syndrome and the more severe nail-patella syndrome (NPS).

Genetic counseling

SPS is inherited in an autosomal dominant manner.

Management and treatment

Early surgical treatment, pain relief therapy and supportive measures should be offered.

Expert reviewer(s)

  • Pr Didier LACOMBE

(*) Required fields.

Attention: Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Captcha image
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.