Nail Patella Syndrome
What is nail patella syndrome?
Nail patella syndrome, also referred to as NPS, Turner-Kieser syndrome, or hereditary onychoosteodysplasia (HOOD) is a rare genetic disorder affecting the proper development of the fingernails/toenails, kneecap (patella), elbow and/or hip bone.
The most common symptoms of nail patella syndrome include underdeveloped nailbeds of the fingers and toes (98%), small or absent kneecaps, inability to fully extend elbows due to growth issues of bones, and extra bone growths on the hip bones. In addition, patients are at increased risk for kidney issues and increased pressure in the eye.
What causes nail patella syndrome?
The most common cause of nail patella syndrome is a mutation of the LMX1B (LIM homeobox transcription factor 1 beta) gene that controls the development of our skeletal system, particularly the parts of the body mentioned above. This mutation is passed down from parents to children in an autosomal dominant inheritance, meaning there is a 50% chance an affected parent will pass nail patella syndrome onto their offspring.
How common is nail patella syndrome?
Nail patella syndrome is rare; 1 in 50,000 individuals are thought to be affected with the disease. It affects men and women equally.
How is nail patella syndrome diagnosed?
Most cases of nail patella syndrome are diagnosed at birth or early childhood through careful clinical evaluation and X-ray examinations. Generally, nail patella syndrome is diagnosed clinically based on the symptoms. However, in cases where diagnosis is unclear, genetic testing can be done for the LMX1B gene, which is the most commonly mutated gene in nail patella syndrome.
What are the treatment options for nail patella syndrome?
Unfortunately, there is no cure for nail patella syndrome, but medical and surgical treatments do exist depending on symptoms. Due to increased risk of kidney and eye problems, annual monitoring of blood pressure, urine tests and eye examinations should be done. If screening is abnormal, your doctor may put you on blood pressure and/or eye drop medications. Management of orthopedic symptoms of the knee and/or elbow consists of physical therapy, braces/splints and surgery. Surgical options include an osteotomy (bone cut) to straighten the bones, realignment of the joints and sometimes, joint replacement. Complications of nail patella syndrome include recurrent kneecap dislocations, glaucoma, and kidney problems. Left untreated, patients can develop arthritis, possible blindness and end stage kidney disease needing a transplant.
At the International Center for Limb Lengthening, our treatment of the disease mainly addresses the small or missing patella and issues with any other joints. This is primarily done through a modification of the SUPERknee procedure designed for congenital instability of the patella. Deformity correction of any other joints primarily consists of making an osteotomy and applying an external fixator to very gradually pull apart the affected joint, while the pins hold the bones in place. Contractures (shortening of the joint and muscle) are then addressed through soft tissue releases. Any resulting limb length discrepancies are corrected with internal or external limb lengthening treatment.
Why choose the International Center for Limb Lengthening for treatment of nail patella syndrome?
Deformity correction and limb lengthening are complex processes. Your doctor at the International Center for Limb Lengthening will take the time to make sure you understand all your options and then will customize your treatment to meet your specific needs. Our patients benefit from our team-centered approach with world-renowned surgeons and specialized physician assistants, nurses and physical therapists. We help patients with nail patella syndrome achieve their best possible result.