Eur J Plast Surg (2006) 29: 1–4
J. J. van der Biezen
After thumb duplication: a proposal for evaluation of the result
The ALURRA system
Received: 11 December 2003 / Accepted: 25 October 2005 / Published online: 25 April 2006
# Springer-Verlag 2006
Abstract Thumb duplication is the second most common
congenital hand anomaly after syndactyly [Cohen MS
(1998) Hand Clin 14(1):17; Dobyns JH, Wood VE, Bayne
LG (1993) In: Green DP (ed) Operative Hand Surgery.
Churchill and Livingstone, New York, pp 251–549]. To
gain a functional and aesthetically acceptable thumb,
surgical treatment is necessary in almost all cases. Many
articles have been written on classification systems,
surgical treatment and factors influencing outcome. How-
ever, literature on evaluating the results of surgical
treatment is scarce. Using a mixture of criteria as described
by Cheng et al., Townsend et al. and Tada et al., we
developed a scoring system that enables an objective
comparison of treatment results. We performed surgical
correction of the duplicated thumb on 15 patients with
various anomalies. Eleven had good results immediately,
three had good outcomes after secondary surgery, and one
patient had a normal result. It was not possible to compare
our results with the results described in other studies due to
a lack of similar criteria.
Keywords Thumb duplication
Thumb duplication is a generally accepted term, and is the
second most common congenital hand anomaly with an
incidence of 0.08 in 1,000 live births [2, 4]. It is not,
however, a correct description of the disorder, because
there is a sharing of structures by the two thumbs rather
than duplication of a normal thumb. Hypoplasia and aberrant
tendon insertions are important features, causing impairment
of control and strength in the thumb. Because normal thumb
function is responsible for 40% of the total hand function [7,
9], this deformity can result in a serious handicap [2, 14].
Therefore, to improve on the function and aesthetics of the
thumb, surgical correction is essential in almost all cases.
The aim of surgery is to provide a thumb which has good
function and an aesthetically acceptable appearance.
Creation of a normal thumb should not be expected, but
how can the results of operative intervention be classified?
There is very little literature on the evaluation of postop-
erative results. Our objective was to develop a scoring
system for postoperative analysis that makes comparison
possible. We applied our alignment, ulnar and radial sta-
bility, range of motion and aesthetical aspects (ALURRA)
system to patients operated on in our own clinic.
Classifications of thumb duplication
There are many types of thumb duplication varying from a
bifid distal phalanx to a complete extra thumb including the
metacarpal bone. To categorise the different types, many
classification systems have been developed. The one
developed by Wassel (1969) divides all forms of thumb
duplication into seven types. It is based on the extent of
duplication of the bony structures and is the most
commonly cited study [2, 4, 5].
General surgical principles
Amputation Simple amputation of the extra digit was the
standard treatment in ancient times. However, it is now
known that this often leads to residual deformities or
instability of the joints. Therefore, this technique is no
longer used as the entire treatment, but as merely a part of
the surgical intervention [1–5, 11, 14].
J. J. van der Biezen (*)
Department of Plastic Reconstructive and Hand Surgery,
Medical Centre Leeuwarden,
Henri Dunantweg 2,
8934 AD Leeuwarden, The Netherlands