|Year : 2013 | Volume
| Issue : 2 | Page : 294-302
Unfavourable results in thumb reconstruction
Samir M Kumta
Lilavati, Shushrusha and Jaslok Hospitals, Mumbai, Maharashtra, India
|Date of Web Publication||21-Sep-2013|
Samir M Kumta
1, Vikas, Vinaya Society, Bhagoji Keer Marg, Mahim, Mumbai - 400 016, Maharashtra
Source of Support: None, Conflict of Interest: None
The history of thumb reconstruction parallels the history of hand surgery. The attributes that make the thumb unique, and that the reconstructive surgeon must assess and try to restore when reconstructing a thumb, are: Position, stability, strength, length, motion, sensibility and appearance. Deficiency in any of these attributes can reduce the utility of the reconstructed thumb. A detailed assessment of the patient and his requirements needs to be performed before embarking on a thumb reconstruction. Most unsatisfactory results can be attributed to wrong choice of procedure. Component defects of the thumb are commonly treated by tissue from adjacent fingers, hand or forearm. With refinements in microsurgery, the foot has become a major source of tissue for component replacement in the thumb. Bone lengthening, osteoplastic reconstruction, pollicisation, and toe to hand transfers are the commonest methods of thumb reconstruction. Unfavourable results can be classified as functional and aesthetic. Some are common to all types of procedures. However each type of reconstruction has its own unique set of problems. Meticulous planning and execution is essential to give an aesthetic and functionally useful thumb. Secondary surgeries like tendon transfers, bone grafting, debulking, arthrodesis, may be required to correct deficiencies in the reconstruction. Attention needs to be paid to the donor site as well.
Keywords: Bone lengthening, great toe wrap around transfer, osteoplastic thumb reconstruction, second toe transfer, thumb reconstruction, toe to thumb transfer, trimmed toe transfer, unfavourable results
|How to cite this article:|
Kumta SM. Unfavourable results in thumb reconstruction. Indian J Plast Surg 2013;46:294-302
On the length, strength, free lateral motion and perfect mobility of the thumb depends the power of the human hand.
- -Sir Charles Bell, 1833. 
Attempts to reconstruct the thumb span the history of hand surgery. Techniques of phalangisation, osteoplastic thumb reconstruction, pollicization, and even pedicled toe transfers have been in existence for a hundred years. (Littler).  Within a few years of the introduction of microsurgical techniques in hand surgery, toe to thumb transfer became an established method of thumb reconstruction. Further refinements in microsurgery enabled the introduction of microvascular "component" transfer from the toes to replace component defects of the thumb.
Special attributes of the thumb
The attributes that make the thumb unique, and that the reconstructive surgeon must assess and try to restore when reconstructing a thumb are: Position, stability, strength, length, motion, sensibility, and appearance. 
The aim of thumb reconstruction is to provide an opposable thumb capable of key pinch and grip, which is pain free, mobile, sensate, and aesthetic in appearance.
Indications for thumb reconstruction
Defects of the thumb requiring reconstruction may be broadly classified as component defects or amputations.
Component loss may be of skin and soft tissue envelope, neurovascular, tendon or skeletal components.
Amputations of the thumb can best be grouped according to Lister into the following broad headings:
Thumbs which are of acceptable length and only lack skin cover can be resurfaced by a wide choice of flaps, depending on the extent of the skin defect, such as Moberg's advancement flap, radial innervated cross finger flap, or neurovascular island flap from the ulnar aspect of the middle or ring fingers.
- Acceptable in all respects, except for skin cover
- Sub-total amputation - length doubtful
- Total amputation - basal joint preserved
- Total amputation - basal joint destroyed.
Subtotal amputations, which pass through the proximal phalanx of the thumb, may be treated by simple or complex methods, depending on the unique requirements of the patient. Metacarpal distraction lengthening, cocked hat flap with bone graft or phalangization are relatively simple procedures that can be used.
Amputations of the thumb that require provision of greater length may be reconstructed by one of three different procedures, osteoplastic reconstruction, pollicization or toe-to hand transfer. Each of these procedures is unique, and the exact choice depends on several factors such as the level of amputation, the condition of other digits, tissue availability, patient age, sex, and occupation.
Pre-requisites for a good thumb reconstruction
A detailed assessment of the patient, his age, sex occupation, social status, motivation level, and capability to participate in prolonged post-operative rehabilitation therapy is essential, and allows the surgeon to choose the correct reconstructive procedure for that patient. Good pliable skin around the amputation stump and an adequate first web are absolutely essential at the time of reconstruction. A first web release or flap cover for the amputation stump may be performed before the thumb reconstruction if either of these is inadequate [Figure 1]. Supple joints and mobile fingers are important.
|Figure 1: A case of crush injury hand with bursting injury of thenar muscles, treated by external stabilization and skin grafting. After satisfactory healing, the contracted first web was released with a 4-flap z-plasty and an opponensplasty|
Click here to view
Every procedure described for thumb reconstruction has its own advantages and disadvantages. There are inherent deficiencies in the procedure, which if not properly understood by the patient and surgeon, may be construed as unfavourable results.
The unfavourable results may be broadly grouped as functional and aesthetic. Some are common to all procedures, while others are specific for each type of reconstruction.
The vast majority of unfavourable results can be attributed to wrong choice of procedure. When choosing the right procedure for a patient, several factors have to be taken into consideration. The level of the amputation, quality of surrounding skin, adequacy of first web, presence of injuries or deficiencies in the fingers or the hand, the patients' age, sex, occupation, hand dominance, and ethnicity are all important. Only after several consultations and a detailed assessment of the patient and his requirements, can the doctor and the patient agree upon a procedure of choice.
Since length, position, stability, mobility, sensations, and aesthetic appearance are the key factors on which success of any thumb reconstruction depends, unfavourable results in thumb reconstruction can be attributed to deficiency in one or more of these factors.
The ideal length of the reconstructed thumb should be such as to allow the opposing digits to reach it and provide a satisfactory key pinch and grasp. Comparison with the opposite thumb gives the surgeon an idea of what is missing and what the length of the reconstructed thumb should be. If the reconstructed thumb lacks mobility, the length should be shorter than the normal thumb. If the opposing digits are injured, stiff, flexed or short, the length of the reconstructed thumb should be slightly shorter. In a metacarpal hand, or a hand with thumb and multiple finger amputations, length and position of the reconstructed thumb become even more critical. When multiple toe transfers are planned to reconstruct the fingers and the thumb, the fingers should be reconstructed first. The patient is then allowed to use the hand with an artificial thumb post. The position and length of the thumb can then be more accurately judged so as to be able to oppose to the reconstructed fingers.
Adequacy of the first web space, and presence or absence of a mobile carpo-metacarpal joint is critical in deciding thumb position. If the CMC joint is functional, and first web space adequate, the thumb can be held in palmar abduction and brought into position to oppose the digits. In patients with a stiff or absent carpometacarpal joint who are to undergo osteoplastic reconstruction, the fixed thumb post needs to be in palmar abduction of around 60°. Injured thumbs with component loss often need additional secondary procedures to improve function, such as an opponensplasty. In bothpollicisation and toe to hand transfers that include the metacarpophalangeal joint of the toe, adjustment of the position of the metacarpal at that joint is very important. This is described in the relevant section of this article on toe transfers.
A mobile carpometacarpal joint greatly enhances the function of the thumb. The greatest advantage of pollicization as a method of thumb reconstruction is that it provides a mobile basal joint for the thumb. Movement of the metacarpo-phalangeal joint and the inter-phalangeal joint are desirable but not very essential for good function of the reconstructed thumb. It is here that pollicizations and toe to hand transfers score over other methods of thumb reconstruction.
Stability of the reconstructed thumb depends on the manner in which bone grafts are fixed, as well as on the balance between flexor and extensor muscles.
Accurate and rigid fixation of the bone graft, and good contact with proximal bone in osteoplastic thumb reconstruction ensures that the thumb remains stable. Poor stabilization can hinder incorporation of the bone graft, leading to resorption or instability.
While pollicized digits and toe transfers carry sensory nerves to the thumb, an additional procedure is required to restore sensations in an osteoplastic thumb. A neurovascular island flap from the middle or ring finger best achieves this. Care must be taken to ensure that the neurovascular island flap is placed in the correct position, as described later in the section on osteoplastic reconstruction.
Non-glabrous skin from adjacent fingers or the dorsum of the hand or forearm looks aesthetically unappealing. More and more, with the advent of microsurgery and super-microsurgery, surgeons are turning to the foot to replace lost components of the thumb. Vascularized nail bed transfer, toe pulp transfer, has all been designed to replace lost thumb tissue with identical tissue from the toes.
Crush injuries of the thumb are often associated with bone comminution and loss. Bone grafting at the time of revascularization can contribute greatly to restoring the stability of the thumb [Figure 2].
|Figure 2: A crush injury of the thumb with severe comminution of the proximal phalanx, treated by primary bone grafting|
Click here to view
Lengthening of the thumb by distraction of the metacarpal or proximal phalanx can considerably improve the thumb function. Osteotomy is done through the metacarpal or proximal phalanx, and distraction is performed slowly at the rate of 0.5 to 1 mm per day. Thumb lengthening is a useful procedure for patients where conditions are not suitable for microvascular reconstruction. Distraction needs to be performed very carefully. Care of the pins, prevention of pin tract infection, slow distraction, and regular monitoring of the progress of distraction are necessary to ensure that the bone alignment is maintained. Generally, the results of distraction of the distal most bone are poor, with the distal segment tapering off due to resorption of the end of the bone. A pre-requisite for distraction is the presence of good quality pliable skin over the thumb tip. If the skin is scarred or tight, it must be replaced before distraction is performed. The distracted thumb lacks joint or nail; hence its appearance and function may be less than desirable [Figure 3].
|Figure 3: (a) A case of thumb and multiple finger amputation with scarred contracted palm. (b) Scar released and replaced with parascapular free flap. (c) Thumb distraction lengthening. (d) New bone formed in gap at the end of 8 weeks. (e) Thumb lengthening complete|
Click here to view
Osteo-plastic thumb reconstruction
Ostoeplastic thumb reconstruction provides useful increase in length for a thumb amputated through the metacarpal or proximal to it. It is a staged reconstruction in which an iliac crest bone graft is attached to the remaining metacarpal, and covered with a tubed flap, either with a distally based radial artery flap or a tubed groin flap. After the tube is divided, the flap is allowed to settle over the next few months. The flap usually needs debulking, which can be performed at the same time as a neurovascular island flap from the middle or ring finger ulnar aspect to provide sensibility to the thumb.
There is no interphalangeal joint, so movements are suboptimal. The flap tends to be bulky, and sensations are referred to the donor finger. In the long term, the bone graft tends to undergo resorption and may fracture.
A little extra care in planning can give much improved results with this method of reconstruction. Osteoplastic reconstruction generally ends up with a bulky thumb. A thick bone graft gives the thumb a drumstick like appearance. To avoid this, the bone graft must be slightly thinner than the metacarpal to which it is fixed. A graft too thin however runs the risk of fracture, so the right balance needs to be achieved.
The dimensions of the pedicled flap need to be measured very carefully. Since the groin or forearm skin is thicker than that over the thumb, the flap must be marked at least 25% wider and longer than required, to accommodate the bone graft and the thickness of the flap. Loss of part of the flap after transfer can be disastrous, as it reduces the width and length of the thumb, and may lead to bone graft exposure and loss of the graft [Figure 4].
|Figure 4: Flap of inadequate dimensions leads to breakdown of the suture line, exposure and resorption of the bone graft, and a short thumb|
Click here to view
The placement of the seam of the tube pedicle is important - it should be placed on the palmar aspect of the thumb, so that the seam can be opened for the placement of the neurovascular island flap. Defatting of the flap can then be done at the same sitting, thus avoiding the need for a separate incision, such as would have been required if the seam was on the dorsum. The site for placement of the neurovascular island flap is also critical. Application of ink on the fingertips before allowing the patient to perform common tasks with the hand, todetect the area of the thumb tip where the ink stains are transferred allows the surgeon to determine the ideal site for flap placement. Two modifications of the classical neurovascular flap have been described to improve the result of the transfer. In order to avoid the problem of sensations being referred to the donor finger, the nerve can be divided and co-apted to the nerve of the thumb.  Instead of a small island, a strip of skin from the ulnar aspect of the donor finger can provide a larger area of sensibility on the reconstructed thumb [Figure 5]. 
|Figure 5: Osteoplastic reconstruction with bone graft + distally based radial artery flap. Debulking of the flap along with a neurovascular island flap from the ulnar aspect of the middle finger gave a functional and aesthetic thumb|
Click here to view
Microsurgical thumb reconstruction
Microsurgical toe-to-thumb transfer has become the mainstay of thumb reconstruction at all levels. It allows one stage total reconstruction of the thumb with mobility, sensibility and near normal appearance, with minimum donor site morbidity if performed meticulously. Toe to thumb transfers can be performed either primarily or secondarily, with similar results. After the initial description of great toe and second toe transfers in 1966, modifications described later such as the great toe wrap around and the trimmed toe transfer improved appearance and function while minimizing donor site morbidity.
Today, the whole great toe, second toe, great toe wrap around, and trimmed toe transfer are the most commonly used methods of microsurgical thumb reconstruction. The vascular basis and surgical anatomy for all these transfers is the same. The differences in functional and aesthetic results and donor site morbidity are well described by Wei.(6).
When choosing the correct toe transfer for any patient, the cosmetic and functional requirements of the patient, age, occupation, level of amputation, skin condition in the hand, and comparison between toe and thumb sizes are all taken into consideration. Ethnic preferences must also be taken into consideration. For example wearing of traditional Indian footwear such as "chappals" is not possible for patients who do not have a big toe; hence Indian patients rarely if ever agree to a great toe transfer, and prefer the wrap around transfer since part of the great toe is preserved, or the second toe transfer.
Unfavourable results of toe-to-thumb transfers
In order to reduce donor site morbidity in the foot, it is advisable not to transfer any skin proximal to the web along with the toe. Hence, it is necessary to ensure that there is adequate good quality skin around the stump. The metatarsophalangeal joint of the foot is much thicker in antero-posterior diameter than the corresponding joint of the thumb; the plantar skin and subcutaneous tissue in the area of the ball of the foot are also much thicker. Hence, adequate supple skin is necessary around the stump of the thumb to accommodate this extra thickness. Very often some skin shortage is inevitable, and small skin grafts are necessary. If the skin is scarred or tight, a pedicled flap such as the groin flap may be done to provide additional skin cover.
The metatarso-phalangeal joint of the toe is an extension joint, whereas the corresponding joint of the thumb is a flexion joint. In order to prevent hyper-extension of the reconstructed thumb at the MP joint, the osteotomy of the metatarsal head needs to be oblique, as described in the figure [Figure 6]. This cannot be done if any attempt to provide extra length to the thumb by shifting the osteotomy to a more proximal level in the metatarsal. In that case hyperextension of the toe at the MP joint is inevitable [Figure 7].
Fixation of the toe
The author prefers a combination of an oblique kirschner wire combined with an interosseous wire to fix the base of the toe to the thumb metacarpal or phalanx [Figure 8]. The kirschner wire can be removed early at 3 weeks. Should there be any rotational or angular malalignment of the toe, this can be manipulated into correct position during therapy.
|Figure 8: Mode of fixation of toe with a single k-wire + interosseous wire loop|
Click here to view
Mobility of the transferred toe is an important advantage of toe to hand transfers. For good mobility, the presence of good flexor and extensor tendons with a good excursion is necessary in the hand. The second toe has a tendency to develop a claw deformity, since its flexor is much stronger than the extensor. Suturing the extensor in full extension first, and then adjusting the tension in the flexor can avoid this. An axial kirschner wire retained for six weeks, and therapy and splintage for a prolonged period after that is necessary to avoid clawing.
Thumb avulsion amputations often involve loss of the flexor and extensor tendons, which are avulsed from their muscle belly at the time of injury. When a toe transfer is attempted in such cases, the proximal end of the flexor and extensor may not be found, and alternative motors need to be utilized. The flexor sublimis of the ring or middle finger, and the extensor indicisproprius are suitable donor tendons. A tenolysis is necessary if adhesions in the palm have reduced the excursion of the flexor tendons.
Co-aptation of sensory nerves is an important step in the transfer. Again, in avulsion injuries, the proximal nerves may not be located, or are avulsed from the median nerve, and nerve transfers and nerve grafts should be used to ensure good sensory recovery.
Aesthetic appearance of the transferred toe is an important consideration. The great toe is bigger than the thumb, the second toe smaller. The wrap around and the trimmed toe transfers have been designed to reduce the size of the big toe to match the size of the thumb [Figure 8]. The second toe however cannot be enlarged to match the thumb. When the toe transfer is transmetatarsal, the additional bulk of the toe in the MTP joint area gives it a cobra head appearance [Figure 9]. Thinning the plantar skin flap and skeletonizing the plantar nerves can help avoid this. This bulk can be entirely avoided if the transfer is performed through the proximal phalanx base, and no skin proximal to the web of the foot is used [Figure 10].
|Figure 10: Second toe transfer done for thumb reconstruction in a 4-year-old boy|
Click here to view
With the wrap around transfer, as with an osteoplastic reconstruction, the bone graft should be thin, to avoid the extra bulk [Figure 11].
|Figure 11: Great toe wrap around flap done in a 7-year-old girl. Excellent thumb function after 15 years|
Click here to view
Donor site problems
Common donor site problems that lead to unfavourable results are wound breakdown in the foot, and scarring, particularly on the dorsum of the foot. Most donor site problems are mainly caused by excess tissue harvest from the donor foot. Thin skin flaps raised to expose the dorsal venous system sometimes undergo necrosis, exposing vital structures on the dorsum.
In the author's experience, nearly 50% of patients had a plantar dominant blood supply to the toes. The 1 st dorsal metatarsal artery was either very deep, or absent. In these patients, excessive dissection from the dorsum to locate the plantar vessels is to be avoided, as it often leads to wound breakdown due to necrosis of the dorsal interosseous muscle. To avoid this, the technique of vessel dissection is described by Wei,  i.e. distal to proximal should be followed. The dorsal digital artery to the toes is located in the first web, and then traced backward. Should the plantar vessel be larger or dominant, the dissection is carried out from the plantar side, but only to the mid-metatarsal level. Any further dissection to the communication between the plantar vessel and the dorsalis pedis to extend the length of the pedicle is to be avoided, as it would result in wound healing problems [Figure 12]. A vein graft may be used instead to extend the length of the pedicle if necessary.
Removal of the great toe causes more deformity in the foot than the removal of the second toe alone. Restricting the transfer to a level distal to the metacarpophalangeal joint, and leaving at least a centimeter of the proximal phalanx base preserves the attachment of the plantar aponeurosis and maintains the stability of the transverse arch.
Use of the second toe avoids this problem. After the removal of the second toe the donor site needs to be closed carefully, and the transverse metatarsal ligaments of either side of the toe are sutured together. Skin grafting on the foot is to be avoided at all costs [Figure 13].
The remaining great toe in a wrap around transfer is closed by using a cross toe flap from the adjacent second toe dorsum to cover the plantar aspect, and a skin graft on the dorsum. This method preserves some length of the great toe, but the aesthetic appearance is less than desirable [Figure 14].
|Figure 14: Cross toe flap for cover of the remaining great toe in a wrap around transfer; Appearance after 15 years|
Click here to view
Post-operative care is just as important as the actual surgery and can make or mar a good result. Regular physiotherapy and splintage are needed to get the optimum movement from a reconstructed thumb or a transferred toe. Early protected mobilization of the toe is started from the 3 rd post-operative day upto the 3 rd week. During this period minor angular or rotational problems can be corrected by gentle manipulation. This is followed by a period of active mobilization. Training in activities of daily living and vocational training follow. Sensory retraining is begun when sensory recovery is first seen.
Care of the donor foot is also very important. The patient is allowed heel walking after the wound has healed and all sutures are removed. Full weight bearing is allowed only after 6 to 8 weeks.
Secondary surgeries to correct unfavourable results
Debulking of flaps in osteoplastic reconstruction, web space release, tenolysis or tendon transfers, and correction of bony problems or arthrodesis are required in about 20% of reconstructed thumbs. The timing of these procedures is variable. The distal inter-phalangeal joint of the second toe tends to remain floppy and an arthrodesis of this joint helps stabilize the tip of the toe and improves key pinch and grasp.
| » Conclusion|| |
A wide range of procedures are available to reconstruct the amputated thumb. Microsurgery has provided numerous options to reconstruct part or whole of the thumb. Proper assessment of the patient enables the surgeon to choose the correct procedure. If planned and executed meticulously, the results of thumb reconstruction can be excellent. Diligent post-operative care, supervised rehabilitation therapy, and early intervention for secondary procedures to treat complications or unfavourable results, can make the difference between a good and an excellent result. 
| » References|| |
|1.||Bell C. The hand, its mechanisms and vital endowments at evincing design. London, Pickering, 1833. |
|2.||Littler JW. On making a thumb: One hundred years of surgical effort. J Hand Surg 1976;1:35-51. |
|3.||Lister, Graham. The choice of procedure following thumb amputation. Clin Orthop Relat Res 1985;195:45-51. |
|4.||Adani R, Pancaldi G, Castagnetti C, et al. Neurovascular island flap by the disconnecting- reconnecting technique. J Hand Surgery (Br) 1990;15 (1):62-5. |
|5.||Hueston J. The extended neurovascular island flap. Brit J Plast Surg 1965;18:304-5. |
|6.||Wei FC. Hand Surgery 1 st ed. Chapter 95: Thumb Reconstruction. USA: Lippincott Williams and Wilkins; 2004. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]