Morphometry of extensors of the thumb with comprehensive review

Abstract

This study was aimed to evaluate the anatomical variations and morphometry of long extrinsic tendons of the thumb namely, extensor pollicis longus and extensor pollicis brevis. Fiftyfive upper limbs of formalin embalmed adult cadavers were dissected. The variation in muscle belly, tendon, its course within dorsal wrist compartment and mode of insertion were noted. The extensor pollicis longus was duplicated in 5.5%. Around 25% tendons were fused with extensor pollicis brevis and through the extensor hood insert into the base of the distal phalanx. The extensor pollicis brevis was absent in 2% and tendon was also duplicated in 2%. In case of absent extensor pollicis brevis tendon, one of the slips from the abductor pollicis longus insert into base of the proximal phalanx instead of the extensor pollicis brevis. The extensor pollicis brevis tendon showed various modes of insertion. The overall length of the extensor pollicis longus and extensor pollicis brevis were 121 mm and 90 mm respectively. The thickness of the extensor pollicis longus at the proximal, middle and distal level of insertion were 1.25 mm, 0.76 mm and 0.55 mm respectively, whereas for the extensor pollicis brevis it was 1mm, 0.75 mm and 0.53 mm. The results obtained from this study may be helpful for the hand surgeons in the management of extensor tendon injuries of the thumb, its reconstructive procedures and in differential diagnosis of dorsal wrist pain.

The Anatomy of the Tendon of Abductor Pollicis Longus and its Morphological Variations: An Anatomical Approach Emphasizing the Clinical Relevance

“…There can be supernumerary tendons or tendons with different points of insertion, contrary to descriptions in the classical literature (Testut et al, 1979;Bergman et al, 1984;O'Rahilly, 1986;Orts, 1987;Williams, 1995;Rouviere et al, 2005). These observations are supported by current evidence, which implies that the percentage of APL muscle variants can range from 33 % to 100 % (Lacey et al, 1951;Coleman et al, 1953;Baba, 1954;Jackson et al, 1986;Brunelli et al, 1991;Khoury et al, 1991;van Oudenaarde, 1991;Yuksel et al, 1992;Zancolli and Cozzi, 1992;Fabrizio et al, 1996;Dos Remédios et al, 2005;Shiraishi et al, 2005;Kulthanan et al, 2007;Paul et al, 2007;Mehta et al, 2009;Bravo et al, 2010;Roy et al, 2012;El-Beshbishy et al, 2013;Thwin et al, 2014;Tewari et al, 2015;Lee et al, 2017;Palatty et al, 2018;Xu et al, 2018;Karauda et al, 2020;Deivasigamani et al, 2021;Gnanasekaran et al, 2021). These data show that the presence of accessory or supernumerary APL tendons in human anatomy is not unusual and is rather common.…”

“…Only Brunelli et al (1991) and van Oudenaarde (1991) reported their use, the latter in only 22 of their 84 samples. These two factors hinder proper comparison since intratendinous dissection could account for the supernumerary tendons recognised in the studies reviewed (Lacey et al, 1951;Coleman et al, 1953;Baba, 1954;Jackson et al, 1986;Brunelli et al, 1991;Khoury et al, 1991;van Oudenaarde, 1991;Yuksel et al, 1992;Fabrizio et al, 1996;Dos Remédios et al, 2005;Shiraishi et al, 2005;Kulthanan et al, 2007;Paul et al, 2007;Mehta et al, 2009;Bravo et al, 2010;Roy et al, 2012;El-Beshbishy et al, 2013;Thwin et al, 2014;Tewari et al, 2015;Lee et al, 2017;Palatty et al, 2018;Xu et al, 2018;Karauda et al, 2020;Deivasigamani et al, 2021;Gnanasekaran et al, 2021). Nonetheless, if the data were to be compared with the present study, the ranges observed would be similar with a mean maximum of five tendons and a two tendon APL being the most frequent pattern.…”

“…The APL tendons have been measured in six other previous studies (Coleman et al, 1953;Palatty et al, 2018;Bravo et al, 2010;El-Beshbishy et al, 2013;Karauda et al, 2020;Gnanasekaran et al, 2021), but to the best of our knowledge, there have been no previous references to inter-and/or intra-observer tests in similar descriptive analysis of APL variability, so this is the first of its kind, guaranteeing the accuracy of the current data and the reliability of the study. Also, these six studies all took the measurements mainly from the point of insertion and not on the spot used in the present study.…”

“…An extensive bibliographical review revealed that accessory APL tendons insert on the trapezium, first metacarpal, APB muscle, OP muscle, flexor pollicis brevis muscle, thenar fascia, volar carpal ligament and TMC joint. However, many of these articles failed to note the presence of double or triple insertions of single tendons, possibly because there was no clear differentiation between tendinous slips and tendons (Lacey et al, 1951;Baba, 1954;Brunelli et al, 1991;Khoury et al, 1991;van Oudenaarde, 1991;Yuksel et al, 1992;Fabrizio et al, 1996;Dos Remédios et al, 2005;Shiraishi et al, 2005;Kulthanan et al, 2007;Paul et al, 2007;Mehta et al, 2009;Bravo et al, 2010;El-Beshbishy et al, 2013;Thwin et al, 2014;Tewari et al, 2015;Lee et al, 2017;Palatty et al, 2018;Xu et al, 2018;Karauda et al, 2020;Gnanasekaran et al, 2021). When the difference was reported, the sites of insertion were identical to those described in the Results section (Coleman et al, 1953;Jackson et al, 1986;Roy et al, 2012;Deivasigamani et al, 2021).…”

“…However, during the last seventy years, several studies (Lacey et al, 1951;Coleman et al, 1953;Baba, 1954;Jackson et al, 1986;Brunelli et al, 1991;Khoury et al, 1991;van Oudenaarde, 1991;Yuksel et al, 1992;Fabrizio et al, 1996;Dos Remédios et al, 2005;Shiraishi et al, 2005;Kulthanan et al, 2007;Paul et al, 2007;Mehta et al, 2009;Bravo et al, 2010;Roy et al, 2012;El-Beshbishy et al, 2013;Thwin et al, 2014;Tewari et al, 2015;Lee et al, 2017;Palatty et al, 2018;Xu et al, 2018;Karauda et al, 2020;Deivasigamani et al, 2021;Gnanasekaran et al, 2021) have shown that the APL tendon is much more variable than reports from the classical literature suggests, reaching proportions of 74.41 % and 85 % according to Roy et al (2012) and Bravo et al (2010) respectively. The anatomical diversity ranges from supernumerary tendons to variations of the point of insertion or tendons that divide themselves into various tendinous slips.…”