ISSN 0972-978X 

  About COAA








Isolated Congenıtal Aplasıa Of Patella Or Congenıtal  Patellar Syndrome: Two Cases Series

Naci Ezirmik, Kadri Yildiz.

Ataturk Unıversıty Medıcal Faculty
Orthopaedıa&Traumatology Department,

Address for Correspondence:
Ataturk Unıversıty Medıcal Faculty
Orthopaedıa&Traumatology Department,
25070, Erzurum, Turkey.

Phone : +905385450559
E-mail :


Congenital patellar syndrome defined bilateral isolated aplasia or hyoplasia of patella. This medical condition is different from Nail-Patella syndrome. This syndrome contain isolated bilateral aplasia or hyoplasia of patella without any abnormalitiy.  There are few cases about this syndrome in the medical literature .

We report two cases that have bilateral isolated aplasia of patella on this paper. And any body abnormalities were not examined in these two cases. According to databases, this is very rare medical condition.

J.Orthopaedics 2010;7(4)e6


Case Report:

We report 43 and 14 years-old two cases (both males) had isolated bilateral aplasia of patella. 43 years old case applied to our clinic when he was 17 years old and 14 years old case applied to our clinic befeore one year ago.

Case 1: 43 years-old case applied to clinic with complaints of deformity in both knees, inability to straighten the knee, little difficulty in  walking and running and rotationel instability while jogging.

The elder case gave normal birth anamnesis.

In knee measuring of 43 years-old case had 160° flexion and 0° extanation on both sides. Active and passive movements of the knees were within normal range, and the quadriceps muscle was of normal strength with gluteus maximus were good. Nails were normal. There were no abnomality on his body.

Case 2: 14 years-old case came to our clinic by pediatric consultation with hardening to walking and going upstairs.

The parents of 14 years-old case gave the history of full term born, normal delivered child, without deformed knees since birth. Also there were an anamnesis worsened from the age of 2 years, after he started walking.

In 14 years-old case  had more deformity on the right knee, which made him difficult to walk. Latter case had 35° flexion, 5° extantion loss on right knee and 40° flexion,  0° extantion loss on left knee. He had an abnormal clinical aspect on his both knees. And he had not nail-finger anomalies or another abnomality on his body. The patient’s immediate family consisting of his parents and two sisters were examined. To their knowledge no blood relative had any related knee problem or any abnormality of their nail sor fingers .The patient was the last child. The parents were found to have normal patellae and fingernails.

On physical examination, there were bilateral isolated absence of patella in both  cases. Absence of both patellae and a hollow sulcus seen in between femoral condyles were the hallmark clinical features in both cases (figure 1,2,3 and 4). Femoral condyles were prominent in both cases. 











Radiographs and magnetic resonance imaging of both knees showed absence of both patellae in both cases (figure 5,6,7,8,9,10). Also ultrasound for case 2 was undergone (figure 11). No other deformity was present in  both patients. No iliac horns were seen on pelvis x-rays. Examinations of upper limbs and other systems were clinically and radiologically normal. Blood parameters were within normal ranges. Genetic studies were normal. Ultrasounds for abdomen were normal. No renal abnormalities were noted. Computerized Axial Tomography showed no the limb length discrepancy and to any other associated disorders in both lower limbs. Limb lengths were equal on both sides. No femur or tibial anomalies were seen. Active and passive resisted physiotherapy had started for both cases. Gait training was given. The patients were on regular follow up every 3 months in each year. They can do today activities, play, squat, sit cross-legged and can lead a near normal life.


Discussion :

Congenital absence (aplasia ) of the patella  are very rare anomaly in the human body(1). Congenital patellar aplasia or hypoplasia associated with genetic disorders belongs to a clinically diverse and genetically heterogeneous group of lower limb malformations in the medical literature (2). Also congenital lower limb malformations without anomalies of the upper limb are estimated to occur in one of 10,000 live births (2). These malformations have an autosomal dominant mode of transmission with 100% penetrance and variable expressivity. And also this syndrome have been linked on the chromosome with the ABO blood group gene (2).

The patella is the biggest sesamoid bone of the human skeleton. And it is formed and located within the tendon of the quadriceps femoris muscle. Its principal role is to facilitate the extensor function of the quadriceps muscle and to protect the ventral cartilage surfaces of the knee joint from other effects (2).

The knee joint is the largest and possibly the most complex synovial joint in the human  body. The patellofemoral joint is a sellar joint between the patella and the femur. The quadriceps, anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) help to each other for normal arthokinematics of the knee through the four bar linkage system. Stability of the patellofemoral joint is proved by the passive and dynamic factors around the knee. The primary dynamic factor is the quadriceps muscles. Quadriceps is strong and the extensor mechanism is enough. This muscle glides in the patellar groove between the femoral condyles in congenital patella hypoplasia or aplasia (2).

Isolated absence of patella is extremely rare. Also It usually causes no disability to the patient. Congenital absence of patella is only one of several anomalies such as nail patella syndrome, anomalies of the femur and fibula, dislocation  of the knee, genu recurvatum, clubfoot, or dislocation of the hip, hypoplastic patella, recurrent lateral dislocation of patella, genu valgum, slip of medial tibial plateau, cubitus valgus, hypoplasia of elbow with decreased range of motion, dystrophy in thumb nails, bifid thumb nails, decrease in the length of nails,  iliac horns, flaring of iliac crests with prominence of anterior superior iliac spines, pelvic abnormalities. Congenital absence of patella without any other osseous anomaly is accompanied by agenesis of the distal third of the quadriceps muscle or severe lateral dislocation of the extensor mechanism (2); but in these cases there were no as this condition.

Carbonara ve Alpert notified that Hereditary Osteo-Onycho Dysplasia (HOOD) showed 92% knee affecting, 11% bilateral absence of patella. HOOD affects primarily  nails, elbows, knees and pelvis (3). Nail-patella syndrome is a rare genetic disorder. But it can cause significant morbidity in several organs, including the musculoskeletal system (4). The nail-patella syndrome is characterized by abnormalities of the nails, patella and radial head, iliac crest and, in some cases, nephropathy. And it showed an autosomal dominant trait. The genetic defect is localized on chromosome 9q34.1. The clinical features in affected individuals vary so much. In some cases the nephropathy may progress to end-stage renal failure, leading to decreased life expectancy (5); but in  these aplastic patellar cases, we did not find any renal changes in clinical follow up. 

Some human developmental syndromes with patellar malformations may be caused by single gene defects or result in some cases from mosaic trisomy 8(2). RAPADİLİNO syndrome, Holt-Oram syndrome, Meier-Gorlin syndrome, Genitopatellar syndrome, Fanconi anemia, Nager syndrome, Coffin Siris syndrome  are the other syndromes that exposed hypoplastic or aplastic patella.


Congenital patellar syndrome is an extremely rare anomaly. Also congenital patellar syndrome causes no major disability to the patient. The treatment is always directed towards the compliants  associated anomalies and matters about the knee (2).

We can say that the absence of patella show minor importance and requires no specific treatment. If there are problems as lateral dislocation, instability, genu recurvatum, discontinuity of the extensor mechanism, some soft tissue release (lateral retinaculum release, hamstring release, medial reefing, full posterior capsule release), proximal and distal alignment procedures, quadriceps plasty, femoral corrective osteotomy  can be applied (2).

These soft tissue operations  is indicated depending upon individual’s clinical findings. The main goal must be to release soft tissue contractures and achieve normal alignment  for knee functions (2).

In these two apylastic patellar cases we did not need any soft or bone tissue operations casuse there are no  compliants or clinical findings. And any renal or other clinical problems did not develop. Last decision was that congenital syndrome is a different syndrome from other patellar apylastic/hypoplastic syndromes.


  1. Varghese RA, Joseph B., Congenital aplasia of the patella and the distal third of the quadriceps mechanism, J Pediatr Orthop B.,  2007 Sep;16(5):323-6.

  2. J Terrence Jose Jerome, M Varghese, B Sankaran, Congenital patellar syndrome, Romanian Journal of Morphology and Embryology 2009, 50(2):291–293.

  3. Carbonara P, Hereditary Osteo-Onycho Dysplasia (HOOD), Am J Med. Sci. , 1964, 248: 139-151.

  4. Doughty KS, Richmond JC., Arthroscopic findings in the knee in nail-patella syndrome: a case report., Arthroscopy. 2005 Jan;21(1):e1-5.

  5. Wildfeuer T, Albrecht G., Nail-patella syndrome, Hautarzt. 1996 Nov;47(11):860-2.


This is a peer reviewed paper 

Please cite as: Naci EZIRMIK: Isolated Congenıtal Aplasıa Of Patella Or Congenıtal  Patellar Syndrome: Two Cases Series.

J.Orthopaedics 2010;7(4)e6





Arthrocon 2011

Refresher Course in Hip Arthroplasty

13th March,  2011

At Malabar Palace,
Calicut, Kerala, India

Download Registration Form

For Details
Dr Anwar Marthya,
Ph:+91 9961303044



Powered by



© Copyright of articles belongs to the respective authors unless otherwise specified.Verbatim copying, redistribution and storage of this article permitted provided no restrictions are imposed on the access and a hyperlink to the original article in Journal of Orthopaedics maintained. All opinion stated are exclusively that of the author(s).
Journal of Orthopaedics upholds the policy of Open Access to Scientific literature.