Добавил:
kiopkiopkiop18@yandex.ru t.me/Prokururor I Вовсе не секретарь, но почту проверяю Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:

Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_777_Библиотеки_им_академика_М_И_Перельмана

.pdf
Скачиваний:
0
Добавлен:
30.08.2026
Размер:
45 Мб
Скачать
96
https://t.me/medicina_free
A. Jester et al.
c
d
Fig. 8.5 (continued)
8 Central Synpolydactyly
https://t.me/medicina_free
a
b
97
Fig. 8.6 Case 4: female, CSPD, Wall and Goldberg Type 2A.Initial radiographies (a). Actual radiographies left side (b) and clinical presentation (c)
98
https://t.me/medicina_free
A. Jester et al.
c
Fig. 8.6 (continued)
References
1. Jordan D, Hindocha S, Dhital M, Saleh M, Khan W. The epidemiology, genetics and future manage­ment of syndactyly. Open Orthop J. 2012;6:14–27.
2. Zhao X, Sun M, Zhao J, Leyva JA, Zhu H, Yang W, etal. Mutations in HOXD13 underlie syndactyly type V and a novel brachydactyly-syndactyly syndrome. Am J Hum Genet. 2007;80:361–71.
3. Ghoumid J, Andrieux J, Sablonniere B, Odent S, Philippe N, Zanlonghi X, etal. Duplication of chromo­some 2q31.1-q31.2in a family presenting syndactyly and nystagmus. Eur J Hum Genet. 2011;19:1198–201.
4. Zguricas J, Bakker WF, Heus H, Lindhout D, Heutink P, Hovius SE. Genetics of limb development and congenital hand malformations. Plast Reconstr Surg. 1998;101:1126–35.
5. Mali KS.Syndactyly: phenotypes, genetics and cur­rent classication. Eur J Hum Genet. 2012;20:817–24.
6. Quinonez SC, Innis JW. Human HOX genes disor­ders. Mol Genet Metab. 2014;111:4–15.
7. Sayli BS, Akarsu AN, Sayli U, Akhan O, Ceylaner S, Sarfarazi M.A large Turkish kindred with syndactyly type II (synpolydactyly). 1. Field investigation, clini­cal and pedigree data. J Med Genet. 1995;32:421–34.
8. Merlob P, Grunebaum M.Type II syndactyly or poly­syndactyly. J Med Genet. 1986;23:237–41.
8 Central Synpolydactyly
https://t.me/medicina_free
99
9. Yucel A, Kuru I, Bozan ME, Acar M, Solak M.Radiographic evaluation and unusual bone forma­tions in different genetic patterns in synpolydactyly. Skelet Radiol. 2005;34:468–76.
10. Dai L, Heng ZC, Zhu J, Cai R, Mao M, Wang H, etal. Mutation analysis of HOXD13 gene in a Chinese pedigree with synpolydactyly. Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2005;22:277–80.
11. Mundlos S, Horn D. Synpolydactyly. In: Mundlos S, Horn D, editors. Limb malformations. An atlas of genetic disorders of limb development. Berlin: Springer; 2014. p.38–40.
12. Barham G, Clarke NM.Genetic regulation of embry­ological limb development with relation to con­genital limb deformity in humans. J Child Orthop. 2008;2:1–9.
13. Zhou J, Chen Y, Cao K, Zou Y, Zhou H, Hu F, et al. Functional classication and mutation analy­sis of a synpolydactyly kindred. Exp Ther Med. 2014;8:1569–74.
14. Sarfarazi M, Akarsu AN, Sayli BS. Localization of the syndactyly type II [synpolydactyly] locus to 2q31 region and identication of tight linkage to HOXD8 intragenic marker. Hum Mol Genet. 1995;4:1453–8.
15. Amiel J, Trochet D, Clement-Ziz M, Munnich A, Lyonnet S.Polyalanine expansions in human. Hum Mol Genet. 2004;13(Suppl 2):235–43.
16. Wajid M, Ishi Y, Kurban M, Dua-Awereh MB, Shimomura Y, Christiano AM. Polyalanine repeat expansion mutations in the HOXD13 gene in Pakistani families with synpolydactyly. Clin Genet. 2009;76:300–2.
17. Akarsu AN, Stoilov I, Yilmaz E, Sayli BS, Sarfarazi M.Genomic structure of HOXD13 gene: a nine poly­alanine duplication causes synpolydactyly in two unrelated families. Hum Mol Genet. 1996;5:945–52.
18. Goodman FR, Mundlos S, Muragaki Y, Donnai D, Giovannucci-Uzielli ML, Lapi E, et al. Synpolydactyly phenotypes correlate with size of expansions in HOXD13 polyalanine tract. Proc Natl Acad Sci. 1997;94:7458–63.
19. Goodman F, Giovannucci-Uzielli ML, Hall C, Reardon W, Winter R, Scambler P. Deletions in HOXD13 segregate with an identical, novel foot malformation in two unrelated families. Am J Hum Genet. 1998;63:992–1000.
20. Debeer P, Bachelli C, Scambler PJ, De Smet L, Fryns JP, Goodman FR. Severe digital abnormalities in a patient heterozygous for both a novel missense muta­tion in HOXD13 and a polyalanine tract expansion in HOXA13. J Med Genet. 2002;39:852–6.
21. Hall JG, Pallister PD, Clarren SK, Beckwith JB, Wiglesworth FW, Fraser FC, et al. Congenital hypothalamic hamartoblastoma, hypopituitarism, imperforate anus and postaxial polydactyly—a new syndrome? Part I: clinical, causal and pathogenetic considerations. Am J Med Genet. 1980;7:47–74.
22. Chandra SR, Daryappa MM, Mukheem Mudabbir MA, Pooja M, Arivazhagan A. Pallister-Hall syn­drome. J Paediatr Neurosci. 2017;12:276–9.
23. Kang S, Graham JM Jr, Olney AH, Biesecker LG. GLI3 frameshift mutations cause autoso­mal dominant Pallister-Hall syndrome. Nat Genet. 1997;15:266–8.
24. Hall JG.Pallister-Hall syndrome has gone the way of modern medical genetics. Am J Genet C Semin Med Genet. 2014;166:414–8.
25. Wall LB, Bae DS, Oishi SN, Calfee RP, Goldfarb CA.Synpolydactyly of the hand: a radiographic clas­sication. J Hand Surg Eur. 2016;41:301–7.
26. Stelling F.The upper extremity. In: Furgusion A, edi­tor. Orthopedic surgery in infancy and childhood. Baltimore: Williams & Wilkins; 1963. p.304–8.
27. Turek S.Orthopedic principles and their application. Philadelphia: Lippincott; 1967.
28. Buck-Gramcko D, Behrens P. Classication of poly­dactyly of the hand and foot. Handchir Mikrochir Plast Chir. 1989;21:195–204.
29. Jose RM, Timoney N, Vidyadharan R, Lester R.Syndactyly correction: an aesthetic reconstruction. J Hand Surg Eur. 2010;35:446–50.
30. Lundkvist L, Barfred T.A double pulp ap technique for creating nail-folds in syndactyly release. J Hand Surg Br. 1991;16:32–4.
31. Buck-Gramcko D. Pollicization of the index nger. Method and results in aplasia and hypoplasia of the thumb. J Bone Joint Surg Am. 1971;53:1605–17.
32. Flatt A.Practical factors in the treatment of syndac­tyly. In: Symposium on reconstructive hand surgery, vol. 9. St Louis: Mosby; 1974. p.144–56.
Thumb Polydactyly
https://t.me/medicina_free
Christiannevan Nieuwenhoven andStevenHovius
9
Abstract
Thumb polydactyly or radial polydactyly is a congenital hand difference in which the patient presents with an extra digit at one or two thumbs. Together with syndactyly, clinod­actyly and camptodactyly, thumb polydactyly is one of the most common congenital upper extremity differences.
To structure the variable phenotypic pre­sentations of thumb polydactyly, several clas­sication systems can be used. The most widely used is the Wassel classication, fol­lowed by the Rotterdam classication includ­ing different triphalangeal thumb phenotypes as well. Later evaluation of postoperative results of the different types of thumb poly­dactyly will be inuenced by the choice in classication made.
In this chapter, the examination at rst con­sultation is described since it is important to perform this systematically, not missing out on less conspicuous differences or even differ­ences on the contralateral hand.
However seen as a relatively simple differ­ence, its treatment can be very complex. The goal is to obtain a functional thumb, without instability and deviation, and is aesthetically close to normal. Except for the abnormal osse-
C. van Nieuwenhoven (*) · S. Hovius Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands e-mail: c.vannieuwenhoven@erasmusmc.nl
ous structures, exor and extensor tendons can have aberrant insertions and connections. The primary operation is the major one, addressing to all differences and avoiding corrective oper­ations later in life.
Keywords
Radial polydactyly · Thumb · Congenital Surgical treatment
9.1 Introduction
Thumb polydactyly, also radial polydactyly, refers to the disorder in which patients have an extra digit at the thumb aspect of the hand on at least one extremity. Polydactylous hands and footprints have been found when studying rock art and petroglyphs, some dated 1000. The rst time that polydactyly was referred to in lit­erature was in the Old Testament, where in a battle in Gath, a giant had six ngers on each hand, and six toes on each foot. A Dutch anato­mist and alchemist, Theodor Kerckring, rst described the difference in the seventeenth cen­tury. Since then, many reports have been made on polydactyly. The preaxial polydactyly can be separated into ve types according genetic litera­ture: thumb polydactyly; polydactyly of a tripha­langeal thumb; polydactyly of an index nger; polysyndactyly and hallux polydactyly [1]. For this chapter, the focus will be directed toward the
© Springer Nature Switzerland AG 2023 G. Pajardi (ed.), Pediatric Hand Surgery, https://doi.org/10.1007/978-3-031-30984-7_9
101
102
https://t.me/medicina_free
C. van Nieuwenhoven and S. Hovius
thumb polydactyly. Polydactyly with a triphalan­geal thumb will be described in the chapter on the triphalangeal thumb.
According to the OMT classication, poly-
dactyly of the hand is a Malformation with an Abnormal axis formation/difference of the Handplate, Radioulnar axis (2iii) [2]. Previously, polydactyly was categorized as radial, central and ulnar polydactyly in the modied Swanson classication in group III, Duplications as Radial polydactyly including triphalangeal thumb [2]. In the OMT classication, ulnar polydactyly has been categorized in the same group as the radial polydactyly, whereas the central polydactyly was proposed to be part of the unspecied axis iii. complex recently by Baas etal. [3].
Together with syndactyly, clinodactyly and
camptodactyly, thumb polydactyly is one of the most common congenital upper extremity differ­ences seen by dedicated congenital hand specialists.
The incidence of polydactyly depends on the
population studied and the denition used. Region, ethnicity and combined numbers of all polydactylies, or only radial or ulnar-sided poly­dactyly, provide very different incidences in pub­lished series. The incidence is estimated to be
0.3–3.6 per 1000 live births and 1.6–10.7 per 1000in the general population [4, 5], with males twice as often affected as females. Variability in incidence is based on the population studied and the denition used for thumb polydactyly. It is believed that the incidence of thumb polydactyly with or without a triphalangeal component is highest in people of Asian descent. Thumb poly­dactyly represents up to 90% of all polydactyly cases in the Chinese population [6].
In a recent Swedish population study, the
thumb polydactyly is mentioned to have a rela­tive incidence of 2.3 per 10,000 live births. The thumb polydactyly without a triphalangeal com­ponent was predominantly present in the male population (58%) with 56% on the left side and 15% bilaterally in this study [4]. In approxi­mately 24% of cases, thumb polydactyly has an inherited pattern. Associated anomalies were seen in 22% of cases [4]. In our patient popula-
tion, preaxial polydactyly characterized accord­ing to the OMT classication [2] was seen in 124 out of the 954 diagnoses with 29% bilaterally affected patients and 39% only right side affected and 32% only left side affected hands.
Thumb polydactyly mostly occurs as an iso­lated and sporadic anomaly, however, in the Online Mendelian Inheritance in Man (‘OMIM’) database, it is mentioned as part of over 125 dis­tinct syndromes and phenotypical associations, including Holt–Oram syndrome, Townes–Brocks syndrome and Fanconi’s anaemia. In our popula­tion, cases were additionally associated with cra­niofacial syndromes, Greig cephalosynpolydacyly, Nager, Klippel–Feil and VACTERL. In the Human Phenotype Ontology (HPO) database, preaxial hand polydactyly as a patient’s feature is related to 59 different diagnoses. Therefore, mul­tidisciplinary knowledge on the phenotypes and syndromes is in our opinion mandatory to treat these patients with a high quality of care.
9.2 Embryology andGenetics
CULAs arise during upper limb development, which takes place between the fourth and eighth weeks of gestation. During these 4weeks, a fully functional hand is formed along three axes of development: The proximal–distal axis, the dor­sal–ventral axis and the anterior–posterior (or ‘radial–ulnar’) axis. Growth and differentiation of tissue along the axes are orchestrated through genetic and molecular signalling pathways, which arise from areas of specialized cells in the limb bud called ‘signalling centres’ [79].
In the development of polydactyly, the radial– ulnar axis is the most important. This axis is formed along the Zone of Polarizing Activity (‘ZPA’), where Sonic Hedgehog (‘SHH’) pro­teins regulate ulnarization and widening of the limb (Fig.9.1) [10]. Disruption of SSH signalling pathways may result in radial polydactyly. Moreover, mutations of SHH and GLI3 are asso­ciated with various phenotypes of radial polydac­tyly [1113] and triphalangeal thumb [1418]. The complex genetic and molecular interactions
9 Thumb Polydactyly
https://t.me/medicina_free
103
Fig. 9.1 Rotterdam classication for polydactyly
result in a highly variable clinical presentation of radial polydactyly, ranging from a rudimental skin tag to very complex triplications of the thumb.
9.3 Patient Presentation
The disorder is easily detected after birth leading to a cosmetic and functional concern with the parents and if not treated, to cosmetic concern of the affected child. Additionally, depending on the level of the duplication, it can cause functional impairment. Most parents or patients will pursue surgery for restoring functional anatomy, however, affected by abnormal embryological development of osseous structures and soft tis­sues, normal aesthetic and functional results are not to be expected. Results on functionality and
aesthetics with regard to manual ability, partici­pation and quality of life in patients with thumb polydactyly are scarce.
Nowadays, a growing number of polydacty­lies are seen with increasing ultrasound tech­niques and experience of examiners. Therefore, more parents might be referred to a congenital hand team to have more information on the dif­ference and possible associated syndromes.
9.4 Classication
As mentioned before, polydactyly can be arranged according to a genetic classication into ve types or classied as a part of the congenital hand differences in the OMT. These classica­tions might give information on the genetic and/ or embryologic nature of the difference, but it
104
https://t.me/medicina_free
C. van Nieuwenhoven and S. Hovius
doesn’t give information on the phenotype and possible related surgical treatment options.
In order to structure the variable phenotypic presentation, thumb polydactyly cases can be cat­egorized using different types of phenotypic­based classication systems. In choosing such a classication system, later evaluation of the results of the different types of thumb polydac­tyly is inuenced by this choice.
Since soft tissue anomalies are harder to visu­alize, most classication systems are based on osseous conguration, which can be shown using X-rays. These classication systems play an important role in communication between spe­cialists, in the evaluation of treatment outcomes, and in supporting clinical decision-making. However, in using the osseous-based classica­tion systems, one should not overlook the addi­tional soft tissue differences.
The most widely used system for thumb poly­dactyly is the Wassel classication [19]. Seven types of osseous congurations are described: types I–VI represent distal-to-proximal levels of thumb polydactyly, while type VII represents thumb polydactyly with a triphalangeal compo­nent. The three most common types of radial polydactyly are type IV (30–46%), type II (9–25%) and type VII (7–32%), with varying occurrence across different case series, e.g. areas in the world.
This classication is easy to apply, but the clinical relevance is limited by the inability to classify surgically important features of radial polydactyly (e.g. diverging components or hypo­plasia), features that inuence outcome. This has led to the introduction of many alternative clas­sication systems [20, 21], such as the Rotterdam classication for radial polydactyly [20], inte­grating elements of the Wassel [19], Buck­Gramcko [22], and Upton [23] classication, into an all-embracing classication system for thumb polydactyly including triphalangeal components and triplications (Fig.9.1) [24].
In a study, incorporating patients from two large European congenital hand units (Hamburg and Rotterdam), the occurrence of the different
types of thumb polydactyly was investigated, evaluating a total of 520 available X-rays from both units from the period 1980 to 2012. Both the Wassel and Rotterdam classications were applied. A comparative historical cohort was extracted from the literature, pooling 1723 eligi­ble cases of thumb polydactyly to describe the frequency of the different types reported in the literature. A large part (40%) of the studied popu­lation could not be classied using the Wassel classication, compared to 6% studied in the lit­erature. However, all study cases could be classi­ed using the Rotterdam classication. All the unclassiable cases had aberrant components: triphalangeal, deviating and hypoplastic. This implies that the Rotterdam classication is more suited for describing the entire spectrum of thumb polydactyly and guidance in surgical treat­ment. Both classications show a good overall intra-observer and fair inter-observer reliability regardless of the experience of the person using the classication system.
According to these results, the Rotterdam classication is best suited for research purposes, even if an inexperienced observer performs anal­ysis. However, for daily practice in non-research environment, the use might be too time-consuming.
9.5 Physical Examination
At rst consultation, following medical history and general physical examination, both upper limbs are examined, and if indicated or a syn­drome is expected, the lower limbs as well. If the ngers are normal, with normal hand and nger creases, and a normal hypothenar region, the examination can focus on the radial side of the hand. In our experience, it is worthwhile to per­form this systematically, as quite often more anomalies are present. Don’t be distracted by the major difference, overlooking the less major differences.
The examination is performed systematically. The thenar musculature varies widely from nor-
9 Thumb Polydactyly
https://t.me/medicina_free
105
mal to severely hypoplastic. In Wassel I and II, the thenar musculature is mostly normal, in con­trast to Wassel V, VI and VII.
Hypermobile joints should always be related to the other joints in the hands. It is important to look for creases on both the dorsal and palmar sides. If creases are present, then an active move­ment in that particular joint can be expected.
The CMCJ in polydactyly can be normal, stiff or hypermobile. If abnormalities in the CMCJ are present, they are mostly encountered in the more proximal polydactylies. If polydactyly is situated at the CMCJ, the MCPJ in the best thumb can be near normal. In these cases, the movement is dependent on the presence of a syndactyly between the duplication.
Depending on the location of the polydactyly, the MCPJ can be stiff, normal moving or hyper­mobile and hypoplastic. For instance, in a poly­dactyly involving the MCPJ, both thumbs move as a block. In most of these cases, the radial-sided thumb is hypoplastic and stiff, and the ulnar thumb is the better one.
Finally, the IPJ can present with normal move­ment, stiffness or hypermobility. If the duplica­tion is at the IPJ, both parts can move as a block. The range of motion in those cases is typically less than in a normal IPJ.In an asymmetric dupli­cation at the IPJ, the best-developed part usually moves better.
Normal examination includes extrinsic and intrinsic movement, but difcult to perform in a newborn. However, exion and extension can be evaluated, as well as the presence of palmar abduction. In radial polydactyly, the exor polli­cis longus is Y-shaped in the majority of cases, with a less developed tendon to the most hypo­plastic thumb. Therefore, exion can be seen simultaneously in both thumbs. Moreover, the exor tendon can have its insertion on the radial side for the ulnar thumb, and ulnar side of the radial extra thumb, causing a more deviating ex­ion in the IPJ.This is especially true for the type 4 and more proximal polydactylies.
The extensor apparatus is usually less devel­oped or absent in the more hypoplastic thumb. It can be Y-shaped as in the exor and asymmetri-
cally attached, therefore, deviating the distal part. The ngertips can be either normal or asymmet­ric. The asymmetric side is typically found on the opposing sides of the two thumbs. The nails are smaller and asymmetrical in most cases. The rst web is nearly always normal in the distal duplica­tions. In more proximal polydactylies, the rst web can be narrower than the normal contralat­eral side.
9.5.1 Patient Selection
Polydactylies are usually treated surgically. Functional impairment can vary from slight to severe, depending on the extent of the deformity. Polydactylies can be a nuisance in, for example, shaking hands, putting hands in pockets or nar­row spaces and in wearing gloves. However, most parents visit the outpatient clinic with their child for aesthetic and social reasons. In patients with a syndrome with serious concomitant disease, sur­gery can be delayed or even be avoided.
9.5.2 Treatment/Surgical Technique
Thumb polydactyly is seen as a relatively simple difference; however, its treatment can be very complex. The aim of surgical intervention in thumb polydactyly is to obtain a functional thumb, without instability and deviation, and is aesthetically pleasing or acceptable. Except for the abnormal osseous structure with joint incon­gruence, the exor and extensor tendons can have aberrant insertions, inuencing the line of pull with regard to future deviations. In addition, aberrant and intricate connections may exist between exors and extensors, affecting thumb movement. In the more proximal polydactyly types, intrinsic muscles might be hypoplastic or absent. In most cases, the thumb is inadequate in size, width and nail development compared to the non-involved opposite side in unilateral cases. However, it is difcult to address these latter hypoplastic features when reconstructing a thumb polydactyly.
106
https://t.me/medicina_free
C. van Nieuwenhoven and S. Hovius
Taking into account all the features of recon­struction in thumb polydactyly surgical approaches have been rened over the years. Different techniques to treat thumb polydactyly can be identied.
The timing of surgery is not xed at a certain age. Surgery is recommended at the end of the rst year of life by many authors, as it is impor­tant to be able to identify the structures properly and to minimize the anaesthetic risks. In a recent study, patients operated at an age older than 2years had signicantly better results than chil­dren before the age of 1year regarding patient­reported scores. No such difference was found for patients operated between ages 1 and 2years [25]. This suggests that timing might be best after the age of 1 year only taking the results into account, and even later if anesthesiologic and psychological risks are taken into account.
In the end, most essential for good long-term good results is the knowledge of patho­embryology and patho-anatomy [26, 27]. Try to visualize aberrant anatomy without too much dis­section! In general, in evaluating results, experi­enced surgeons are reported to have better results in outcomes [25].
9.6 Operative Treatment
A number of principles in the treatment of thumb polydactyly can be listed in Table9.1. The most versatile and widely applied surgical treatment for thumb polydactyly is the resection and recon­struction technique. The majority of cases can be treated using this technique, indicated whenever one of the extra thumbs is better developed than the other (oating-type thumb polydactyly excepted). In most cases, the ulnar thumb is bet­ter developed and the radial thumb is resected. Resection of the radial thumb has the added ben­et of preserving the ulnar collateral ligament, playing a key role in stabilizing the MCPJ during pinch grip and prehension. Furthermore, the scar will be situated dorsally or on the radial side of the remaining thumb, not impeding with sensa­tion of the ulnar-sided pulp of the thumb. Several techniques have been described to improve
Table 9.1 Principles in treating thumb polydactyly
• “Make one thumb out of two. It is not a simple excision of one”
• Decide which thumb to be kept
• Preserve tendons, ligaments and skin of the discarded thumb to align, balance and augment the residual thumb
• Perform as much correction as possible and necessary during the rst operation on both soft tissues and bones
• Be aware of and search for less obvious anatomical anomalies
• Align articular surfaces as axial and as congruent as possible by transverse and longitudinal osteotomies
• Perform ligament reconstructions or releases
• Balance tendon insertions
• Adjust skin cover as accurately as possible. Excess of skin will not disappear in time
• Postoperative dressings should be meticulously applied, protect the reconstruction and resistant to removal by the child
appearance and function, as well as attention to pulp size and girth [28], separate techniques for type III reconstruction [29], support of collateral ligaments in type IV [30] and rebalancing of ten­dons [31].
When analyzing literature on the long-term outcome of thumb polydactyly treatment, only few reports are found with overall outcome [32
34] and one only on thumb size and appearance
[35]. In a recently published thesis, an extensive analysis was performed on the outcome of surgi­cally treated thumb polydactyly [36]. Most important lessons were: reporting outcome starts with the implementation of a reliable and all comprising classication for thumb polydactyly regarding the pre-operative situation; and the use of a reliable and clinically weighted outcome assessment system [3739]. If analyzed accord­ing to these conditions, type IV had worse func­tional outcomes than type II and IV-Tph if the thumb was operated only once. However, if mul­tiple surgeries were needed, an overall worse out­come is to be expected. Furthermore, overall outcome signicantly improves when the rst operation is performed by an experienced sur­geon, specialized in congenital upper limb anom­alies [25]. Regarding the Bilhaut–Cloquet procedure, this technique is not worthwhile in