Kirner deformity is characterised by a curvature of the distal phalynx of the 5th digit in both a palmar and radial direction.
The deformity typically presents in late childhood to early adolescence, although a mild deformity may be present at birth. Both sexes are affected, although there is a predominance of cases in women reported, perhaps indicating a gender predilection 2.
Inheritance has been described as autosomal dominant with variable penetrance, however many cases appear sporadic 1-2.
Associations may include:
- Down syndrome
- pes cavus
- absence of the flexor digitorum superficialis tendon in the 5th digit
- myositis ossificans
- Turner syndrome
- Silver syndrome
- Cornelia de Lange syndrome
- congenital cardiac abnormalities 2
Although presentation is usually with deformity, in some patients swelling and erythema may be present 4.
Radiographic changes affect the terminal phalanx of the 5th digit, in most cases bilaterally, and are characterised as:
- palmar and radial deviation
- radiolucent nidus (1-2 mm) within the terminal tuft 2
- shortened diaphysis
- sclerosis of the diaphysis
- metadiaphyseal defect
Treatment and prognosis
As this is purely as cosmetic problem (unless fine motor skills are required) medical treatment is optional. It is unclear whether splints alter the degree of deformity 4. Osteotomy is an option, if treatment is deemed necessary.
History and etymology
It was first described by J Kirner in 1927 3.
- 1. Scott CE, Engber W. Kirner's deformity: a case report and review. Iowa Orthop J. 1996;16 : 167-9. - Free text at pubmed - Pubmed citation
- 2. David TJ, Burwood RL. The nature and inheritance of Kirner's deformity. J. Med. Genet. 1972;9 (4): 430-3. doi:10.1136/jmg.9.4.430 - Free text at pubmed - Pubmed citation
- 3. Kirner J "Doppelseitige Verkrummungen des Kleinfingerendgliedes als selbstandiges Krankheitsbild." Fortschritte aufdem Gehiete der Ronigenstrahien, 36, 804-806.
- 4. Dykes RG. Kirner's deformity of the little finger. J Bone Joint Surg Br. 1978;60 (1): 58-60. J Bone Joint Surg Br (pdf) - Pubmed citation
- 5. Khalid S, Khalid M, Zaheer S et-al. Kirner's Deformity Misdiagnosed as Fracture: A Case Report. Oman Med J. 2012;27 (3): 237-8. doi:10.5001/omj.2012.53 - Free text at pubmed - Pubmed citation