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Ulnar Deficiency Classification Essay

In congenital radioulnar synostosis there is congenital fusion of the proximal ends of the radius and ulna, fixing the forearm in varying degrees of pronation. That means upper end of both the bones, radius and ulna are fused, making it impossible for radius to move for pronation and supination movement. In about 60 percent of cases, involvement is bilateral.

Synostosis stands for osseous union of two adjacent bones can involve any part of the upper extremity. Congenital radioulnar synostosis results from failure of segmentation between the radius and ulna which leads to loss of motion between two bones [pronation and supination]. The synostosis occurs at upper end of radius and ulna.

Male and female incidence is approximately equal.

Types of Congenital Radioulnar Synostosis

Wilkie originally described two types of congenital radioulnar synostosis

  • Type 1 – Complete synostosis
  • Type 2 – Partial synostosis. Often associated with radial head dislocation.

Four types of congenital radioulnar synostosis are described now [Cleary and Omer]

  • Bony synostosis
  • Fibrous synostosis
  • Synostosis associated posterior dislocation of the radius
  • Synostosis associated anterior dislocation of the radius

Bony Synostosis

It is true congenital radioulnar synostosis where ulna and the upper end of the radius are closely fused together. The radial head may be fused to the ulna, or it may be completely absent.

The radial shaft is bowed to a greater degree than normal and is longer and thicker than the ulna.

Fibrous Synostosis

It is rarest type. The ulna and radius may be attached, at a point just distal to their upper ends, by a short, thick, interosseous ligament that prevents any pronation or supination, just as if the bones were fused together. This is not a true synostosis.

Congenital Radioulnar Synostosis Associated with Dislocation of Radius

The second type is that in which the radial head is malformed and dislocated posteriorly or anteriorly.The proximal end of the radius is fused with the upper shaft of the ulna.

Congenital radioulnar synostosis is hereditary in some cases, appearing to be a dominant trait . It is caused by a developmental arrest of longitudinal segmentation.

Associated Anomalies

  • Hip dislocation
  • Knee anomalies
  • Clubfoot
  • Polydactyly
  • Syndactyly
  • Madelung deformity
  • Ligamentous laxity
  • Thumb hypoplasia
  • Carpal coalition
  • Cardiac Anomalies
  • Renal anomalies
  • Neurologic anomalies
  • Abnormalities of GI system
  • Acrocephalosyndactyly
  • Apert syndrome
  • Carpenter syndrome
  • Arthrogryposis
  • Mandibulofacial dysostosis
  • William syndrome
  • Klinefelter syndrome
  • Holt-Oram syndrome
  • Microcephaly
  • Multiple exostoses

Clinical Presentation

The average age at diagnosis is about 6 years old. It is not a painful condition in the childhood. Pain may be reported in teen years.

The main complaint is functional deficit. The functional disability depends on severity of the deformity and whether or not it is bilateral. The severity is determined by position of forearm in pronationsupination plane.

A forearm fixed in pronation is severest form of the deformity as patient is not able to compensate for the resulting loss of function by shoulder motion.

Midcarpal and radiocarpal joints can be hypermobile in an attempt to compensate or disguise  the limitation. An abnormal carrying angle of the elbow [angle between arm and forearm axis.With age, as the child approaches teenage symptomatic radial head subluxation may develop.

Inability to supinate forearm is major complaints.  The child may have difficulty with such activities as turning a doorknob, buttoning shirts, and handling eating utensils.The extension of the elbow may be limited.

Patients with unilateral problem have lesser limitations.

The involved forearm is thinner than normal and somewhat twisted in appearance.


AP and lateral radiographs are able to diagnose congenital radioulnar synostosis. Radiographic followup is required even in asymptomatic cases to note for any progressive subluxation of radial head.


Each patients should be individually evaluated to determine the treatment required. Surgical treatment may be considered on the severity of the deformity and if the condition is bilateral.

Patients with neutral rotation, mild pronation or without much functional limitations should not be subjected to surgery. Decision for surgery should base onl functional limitations than on absolute forearm position.

Subluxated radial heads are excised at skeletal maturity. For other procedures  surgery should be performed in preschool age.

Mobilization Procedures

These surgeries aim at achieving and maintaining motion at the synostosis site. These involve excision of synostosis and interposition of inert tissue to prevent reformation of synostosis,

However, synostosis typically recurs  inspite of  the interposition of silicone, fat, or muscle. Recently, results with the interposition of vascularized fat graft have been encouraging.


A swivel prosthesis that was placed in radius and aimed at motion restoration also yielded poor results and is not popular  anymore.

Tendon Transfers

Tendon transfers are also combined with mobilization procedures. For example flexor carpi ulnaris transfer dorsally around the ulna, and the extensor carpi radialis longus to the volar aspect to achive better supination.

Osteotomy and Derotation

It is most preferred and succesful procedure. It involves osteotomy through the fusion mass and  fixation with transcutaneous pins

In case of  unilateral deformity, the affected forearm is placed in neutral rotation. In bilateral deformities, one side is placed in 20-30 degrees of pronation and the other, in 20-30 degrees of supination.

Prognosis of Congenital Radioulnar Synostosis

Overall, surgical treatment has high failure rates.  The use of postoperative indomethacin or low-dose limited field irradiation within the first 5 days after surgery has been shown to be effective in limiting the recurrence.


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Filed Under: Pediatric Disorders


Ulnar hypoplasia is a rare longitudinal limb deficiency in which the ulna shows various degrees of deficiency. The condition is normally associated with radial defects, and in severe cases there is a reduction of postaxial/ulnar digits. Ulnar deficiency is an integral part of several syndromic malformations like Weyer's oligodactyly syndrome, limb/pelvis hypoplasia/aplasia syndrome, and ulnar-mammary syndrome. Here, we report an isolated unilateral ulnar deficiency in a boy who was a product of a consanguineous marriage. The subject demonstrated mesomelic shortening of the left arm with reduced zeugopod and autopod, and preaxial absence of two fingers. Additional findings in the affected limb were severe flexion contracture at the elbow joint, reduced and narrow palm, hypoplastic digits, and clinodactyly. Roentgenographic study revealed rudimentary ulna, dysplastic and posteriorly dislocated radius, crowding of carpals, and complete absence of digit rays of the thumb and index finger. Despite this anomaly, the subject could manage his daily life activities well. We present detailed clinical features and differential diagnosis of this rare limb malformation.

Keywords: Finger reduction, longitudinal defect, limb deficiency, oligodactyly, Pakistani subject, radial dysplasia, ulnar aplasia


Ulnar hypoplasia/aplasia is a longitudinal deficiency at the posterior axis of the upper limb wherein the ulna is partially or completely absent. If the deficiency is incomplete, the ulnar remnant may vary in length and contour. The elbow joint may be in extension or in acute flexion.[1,2] At the shoulder girdle, one may observe considerable muscular atrophy, ligamentous relaxation, and a deep web in the axilla.[1,2] This condition may accompany hypoplasia of the radius. O’Rahilly proposed an anatomical classification of limb anomalies and expanded the concept of intercalary deficiencies.[2] Additionally, oligodactyly is a common presentation and the number of absent digits varies greatly. Depending upon the severity of longitudinal deficiency at the ulnar or radial ray in the zeugopod, the postaxial or preaxial fingers could be omitted, respectively. However, ulnar deficiency with the absence of preaxial digits is extremely rare and has not been much appreciated.[3] In this communication, we present a male child, a product of a consanguineous marriage, with a rare association of ulnar hypoplasia and the absence of two preaxial fingers, the remaining digits depicting postaxial/posterior identities.


The subject, a 12-year-old school-going boy, originates from a rural area of Southern Punjab, Pakistan. His parents were first cousins (inbreeding coefficient, F = 0.0625), and he had four normal siblings (3 brothers, 1 sister). The maternal and paternal ages were 28 and 33 years, respectively, at the time of his birth. The pregnancy had been uneventful and the birth was at home, in the presence of a traditional birth attendant. The study was approved by the institutional review committee and all the information was obtained according to the Helsinki II declaration. The initial ascertainment and detailed clinical examinations were carried out in several visits during 2009-2010.

The subject had normal developmental landmarks, dentition, and intelligence quotient (IQ). He was observed to have an isolated limb anomaly. Upon physical examination, he had a standing height of 146 cm, sitting height 71 cm, arm span 130 cm, head circumference 53 cm, neck circumference 29 cm, and chest 68 cm. There was no family history of any limb or other anomaly.

Clinical examination showed a short left arm [Figure 1A]. The upper arm was thin and weak, and the middle and forearm were reduced in size. The elbow demonstrated limited flexion and extension [Figure ​1A,​B]. The middle arm was flat and depicted restricted supination. The palm was narrow with a few flexion creases [Figure 1C]. The ‘hand’ harbored only three functional fingers identified as third, fourth, and fifth, each comprising two flexion creases at the interphalangeal joints. The thumb and index finger were completely omitted. The posterior finger, that is, the fifth digit, was weak and showed volar inclination [Figure ​1A,​C].

Figure 1

Phenotype in subject; a-e: Photographs and radiograph of upper limbs

In the roentgenograms, the ulna was grossly degenerate and was only represented by a club-shaped decalcified bony island of ~2.5 cm at the distal zeugopod [Figure ​1D, ​E; Table 1]. The radius appeared short, hypoplastic, and dysplastic. In the absence of the ulna, the radius demonstrated a compensatory curvature and maintained a varus concavity of ~20° [Figure 1D]. Its proximal head was ill grown, misaligned, and posteriorly dislocated, and was losing its normal axis along the humeral trochanter. The distal head of the radius was broad, weak, and decalcified, depicting signs of immaturity, and was capped with dysplastic epiphysis [Figure 1D]. In the upper arm, the humerus was short, thin, and decalcified [Figure 1B; Table 1]. Its distal head was dysplastic with ill-developed epiphysis and hence, was unable to support the zeugopod.

Table 1

Anthropometric and roentgenographic measurements of the subject

In the autopod, four carpals were visible which were crowded and malformed [Figure 1E]. Three metacarpals were present which though thin, maintained normal size [Table 1]. At the anterior axis, the ‘third’ finger depicted volar inclination, whereas at the posterior axis, the ‘fifth’ digit showed clinodactyly [Figure 1E]. There was minor cutaneous syndactyly between the fourth and fifth fingers which was not witnessed at the osseous level [Figure 1C] (see Table 1 for detailed roentgenographic measurements).

In the right arm, roentgenograms were unremarkable except for crowding of the carpals. There was no involvement of any other organ system; there were no symptoms of oral, faciocranial, skeletal, or vital internal organs. His parents could not recall any drug exposure during the pregnancy. The subject has fully adapted this limb deficiency and can manage his daily life activities well.


Ulnar longitudinal deficiencies are very rare and their prevalence has been estimated to be 1-2 in 100,000 live births.[4,5] Several different classification systems have been proposed for ulnar ray deficiency (reviewed by Al-Qattan, 2010).[3] O’Rahilly suggested a classification of congenital limb anomalies that was based on anatomical differences.-[1,2] Ogden et al. provided a classification based upon the severity of the ulnar deformity.[6] Bayne considered the degree of ulnar deficiency and also the radiohumeral synostosis.[7] Ogino and Kato provided a system which also integrated into the classification the deficiency of fingers at the ulnar side.[8] Cole and Manske added thumb/first web deformity to the ulnar ray deficiency.[9] Hence, according to the O’Rahilly scheme, the present anomaly can be classified as ulnar-preaxial carpal-phalangeal meromelia.-[1,2] According to the Bayne system, the presentation in our subject is close to type II (i.e., partial aplasia of the ulna). On the other hand, our case is difficult to characterize according to the Ogino-Kato scheme because here the radial digits are omitted and the remaining fingers maintain posterior/ulnar identities. According to the Cole-Manske system, which also considers the absent thumb, the present case is closer to type D. Proximally, when the ulna is absent, the radius can be unstable in its articulation with the humerus and shows proximal dislocation. This situation was appreciated by Kummel who provided a classification of elbow deformity.[10] Accordingly, our case can be classified as type III (i.e., radial head dislocation).

The clinical presentation in our subject is best classified as ulnar aplasia, dysplastic radius, and preaxial oligodactyly. There was no evidence of radioulnar synostosis or fusion at the angle joint, that is, humeroradial juxtaposition. However, severe flexion contracture of the elbow and radial head dislocation were witnessed. The radiocarpal joint was stable. We also considered differential diagnosis and reported cases with the Schinzel syndrome, Marles-Chudley syndrome, Weyer's ulnar ray/oligodactyly syndrome [Online Mendelian Inheritance in Man (OMIM): 602418], limb/pelvis-hypoplasia/aplasia syndrome (OMIM: 276820), ulnar-mammary syndrome (OMIM:181450), Fuhrmann syndrome (OMIM: 228930), and Cornelia de Lange syndrome (OMIM: 122470).[11] However, all these syndromic anomalies can be safely excluded as they show associations of orofacial, cardiac, and/or ectodermal organs.

The studies on hereditary and congenital limb deficiencies are relatively scarce in Pakistan. Only a few reports depicting digit deficiencies have been published.[12,13,14] There is no previous study on longitudinal limb defects.

Congenital limb and/or finger loss is a potentially devastating event which imparts profound physical, psychological, and vocational consequences on the subject as well as his/her family.[15] Despite the potential adverse impact of partial loss or deficiency on daily function and the quality of life, management is not easy and no immediate help is available. Prosthetic and cosmetic measures not only require long-term follow-up and skilled surgical procedures but are also known to offer limited rescue. The etiology of such defects is not fully understood mainly due to the rarity of reported subjects and familial cases, poor understanding of inheritance patterns, and lack of molecular and genetic data. Further studies are warranted on the pathophysiology of longitudinal limb defects to propose better therapeutic and surgical options for the subjects.

Author contributions

MA ascertained the case and helped in data collection. SM analyzed the data and drafted the manuscript. Both authors read and approved the content of the manuscript.


The authors highly appreciate the participation of the subject and his family in this study and are indebted to Drs. Van Heest AE, Ferguson JH, Ogino T, Evans J, Koskimies E, and Goldfarb CA for their expert help in the diagnosis.


Source of Support: This study was supported by the Higher Education Commission, Islamabad and the Pakistan Science Foundation, Islamabad

Conflict of Interest: None declared.


1. Frantz DH, O’Rahilly R. Ulnar hemimelia. Artif Limbs. 1971;15:25–35.[PubMed]

2. O’Rahilly R. Morphological patterns in limb deficiencies and duplications. Am J Anat. 1951;89:155–87.

3. Al-Qattan MM, Al-Sahabi A, Al-Arfaj N. Ulnar ray deficiency: A review of the classification systems, the clinical features in 72 cases, and related developmental biology. J Hand Surg. 2010;35:699–707.[PubMed]

4. Birch-Jensen A. Odense, Denmark: Andelsbogtrykkeriet; 1949. Congenital deformities of the upper extremities.

5. Rogala EJ, Wynne-Davies R, Littlejohn A, Gormley J. Congenital limb anomalies: Frequency and aetiological factors. Data from the Edinburgh Register of the Newborn (1964-68) J Med Genet. 1974;11:221–33.[PMC free article][PubMed]

6. Ogden JA, Watsen HK, Bohne W. Ulnar dysmelia. J Bone Joint Surg Am. 1976;58:467–75.[PubMed]

7. Bayne LG. Ulnar club hand (ulnar deficiencies) In: Green DP, editor. Operative hand Surgery. New York: Churchill Livingstone; 1982. pp. 245–57.

8. Ogino T, Kato H. Clinical and experimental studies on ulnar ray deficiency. Handchir Mikrochir Plast Chir. 1988;20:330–7.[PubMed]

9. Cole RJ, Manske PR. Classification of ulnar deficiency according to the thumb and first web. J Hand Surg Am. 1977;22:479–88.[PubMed]

10. Kummel W. Germany: Bibliotheca Medical (Cassel); 1895. Die Missbildungen der Extremitaeten durch Defekt, Verwachsung und Ueberzahl; pp. 1–83.

11. OMIM. Online Mendelian Inheritance in Man. [Last accessed on 2012 Feb]. Available from: .

12. Ahmad M, Abbas H, Haque S, Flatz G. X-chromosomally inherited split-hand/split-foot anomaly in a Pakistani kindred. Hum Genet. 1987;75:169–73.[PubMed]

13. Malik S, Jabeen N. Zygodactyly with thumb aplasia: An unusual variant in a male subject. J Col Physicians Surg Pak. 2011;21:710–2.[PubMed]

14. Riaz HF, Malik S. Case report of a neonate with congenital transverse deficiency of hand. Pak J Med Sci. 2011;27:1177–80.

15. Dillingham TR, Pezzin LE, MacKenzie EJ. Limb amputation and limb deficiency: Epidemiology and recent trends in the United States. South Med J. 2002;95:875–83.[PubMed]