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Original Article

New Simple Technique for Syndactyly Release

Grahn, Petra M. MD*; Nietosvaara, Noora N. MD*,†; Sommarhem, Antti J. MD, PhD*; Nietosvaara, Yrjana A. MD, PhD*

Author Information
Plastic and Reconstructive Surgery - Global Open: May 2020 - Volume 8 - Issue 5 - p e2842
doi: 10.1097/GOX.0000000000002842
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Syndactyly is one of the most common congenital hand anomalies with a reported incidence of 2:10,000, and it is classified as incomplete or complete, simple, complex, or complicated. In simple incomplete (SI) or simple complete (SC) syndactyly, only soft tissue connects the digits. Complex (C) syndactyly involves bony connections of adjacent phalanges. Syndactyly is complicated in cases with accessory phalanges or abnormal soft tissues. Complicated syndactyly (CC) is usually associated with other congenital anomalies or different syndromes.1–6

The main goal of treatment in syndactyly is to separate fused digits, create a normal web space, and improve both function and esthetics of the hand.7 The recommended timing of syndactyly separation is from 3 to 24 months depending on the web space(s) involved and the type of syndactyly. Children with multiple syndactylies affecting adjacent webs need at least 2 surgeries ≥3 months apart according to most authors.2 Numerous surgical options have been described with graftless techniques gaining popularity, which may lead to fewer complications than procedures using skin grafts. These techniques most commonly utilize a zigzag incision for finger separation with different types of metacarpal advancement flaps to reconstruct the web.8–16

We developed a new simple technique for web reconstruction with a hexagonal metacarpal advancement flap combined with straight midline incisions for syndactyly separation. Short-term results of the first 39 web space reconstructions are presented.


This is a prospective intervention study including all nonsyndromic and syndromic syndactyly patients referred to our institution. Since 2015, 39 web spaces (5 CC, 4 C, 12 SC, and 18 SI) in 26 consecutive patients (24 white, 1 brown, 1 black, 21 male, 10 left, and 9 bilateral) have been reconstructed using a hexagonal metacarpal advancement flap and straight midline incisions (Table 1). Our former technique used the same flap for web reconstruction, but finger separation was done with zigzag incisions.

Table 1. - Patient Demographics and Outcome
Patient Web Space Affected Type Associated Condition Follow-up (y) Web Space Separated Use of Skin Graft and Harvest Site Cosmetic VAS Functional VAS Web Grade by Withey et al18
1 2 SI PIP Poland 3.7 2 80 78 1
2 3 SI PIP 3.4 3 NA NA 0
3 3L (3R) SC (SI PIP) 1.7 3 95 94 1
4 2 SI PIP Poland 2.1 2 94 93 0
3 SI PIP 1.5 3 1
4 SI PIP 2.1 4 0
5 3 SC 1.0 3 82 100 0
4 SC 1.5 4 0
6 2 SI PIP Symbrachydactyly 1.8 2 95 96 1
7 3 SI PIP 1.5 3 100 100 0
8 3 C 2.0 3 87 100 2
9 2 SI DIP 1.2 2 96 86 0
3 SC 0.6 3 1
4 SC 1.2 4 1
10 3 SI PIP 1.5 3 100 100 0
11 3 SC VSD 0.9 3 52 85 0
12 3R C 1.8 3 R Local 63 82 2
3L C 1.8 3 L Inguinal 80 90 1
13 3 (4)* SI PIP Moebius 0.8 3 100 90 1
14 2L (3R) SC (SI PIP) Ulnar aplasia 1.1 2 Local 90 90 0
15 3 SI DIP 1.1 3 90 100 1
16 4 SI DIP 1.0 4 90 100 0
17 2 SI PIP Poland 1.1 2 89 89 1
18 3R (2,4)* CC (CC) Constriction band 1.2 3 R Local 72 63 1
3L (2,4)* SI PIP (SI PIP) 1.2 3 L 94 94 1
19† 3R SC 1.7 (0.5) 3 R –(80) –(90) 2 (0)
3L C 1.7 (0.5) 3 L Local –(80) –(90) 4 (0)
20 2 SI PIP 1.0 2 R 87 100 0
21 3R SI PIP 1.0 3 R 100 100 1
3L SI PIP 1.0 3 L 100 100 1
22 4R SC Hereditary 0.8 4 R 100 100 0
4L CC 0.8 4 L Inguinal 89 100 1
23 4 SC 0.5 4 100 100 0
24 4R SC VSD, bilateral ulnar polydactyly 0.5 4 R 100 100 0
4L SC 0.5 4 L 100 100 0
25 2R (3) CC (CC) Constriction band 0.5 2 R Local 56 64 1
4R CC 0.5 4 R 56 64 0
2L (3) SI PIP (SI PIP) 0.5 2 L 83 96 0
26 4 CC Foot anomaly 0.5 4 79 92 0
()Not separated.
()*Separated earlier using a different technique.
†Reoperation of web creep following postoperative infection. Follow-up time and Withey grade from reoperation in brackets.
L, left; NA, not answered; PIP, proximal interphalangeal joint; R, right; S, simple; VSD, ventricular septal defect.

Fig. 1.
Fig. 1.:
Grading of web creep according to Withey et al.18 Grade 0: soft web, abduction mirrors the adjacent web or equivalent web on the other hand. Grade 1: no web advancement, but thickening of the web with reduced span. Grade 2: creep of web to 1/3 of the distance between base of the web and PIPJ crease. Grade 3: creep of web to 2/3 of the distance between base of the web and PIPJ crease. Grade 4: creep of web to the PIPJ crease. PIPJ indicates proximal interphalangeal joint.

Of the 18 patients with SI syndactyly, 15 ended at the proximal interphalangeal joint and 3 at the distal interphalangeal joint (DIP). Twelve of the 26 patients had an associated condition or syndrome (Table 1). Syndactyly separation was performed at a mean age of 20 months (range, 11–43 months). The more complicated, the earlier the separation was done; CC mean: 13 months (range, 11–14), C mean: 14 months (range, 11–16), SC mean: 18 months (range, 11–43), SI DIP mean: 18 months (range, 15–22), and SI DIP: mean 25 months (range, 11–42). Patient 22 underwent Qube-fix distraction17 of the left side before web reconstruction. Five patients with syndactyly affecting adjacent webs had 2 surgeries at a mean of 7 months (range, 7–50 months) apart. Two of these 5 patients had their first web reconstructions performed with a hexagonal metacarpal advancement flap and zigzag incisions (Table 1).

The length of the operation (incision to closure) was registered in minutes. Minor and major complications were recorded. Follow-up (FU) was scheduled at 6 months and 1, 3, 5, 10, and 20 years after surgery to be performed by an occupational therapists. Photographs were taken preoperatively and during FU. Web space was calculated from photographs by an independent observer using a method created by Withey et al18 (Fig. 1). Parent’s satisfaction regarding both cosmetic and functional outcome was registered using a 0–100 Visual Analog Scale (VAS). Parents’ consent was obtained to use pre- and postoperative photographs of their children’s hands for research purposes.


Incisions are marked on the skin with metacarpophalangeal (MP) and interphalangeal (IP) joints in extension (Fig. 2). (See Video [online], which displays the surgical technique and postoperative care.) Tourniquet is inflated. The dorsal midline is incised, and the hexagonal flap is elevated (Fig. 3). Buck-Gramcko19 plasty is used if necessary. In C syndactylies, synostosis is separated with a chisel or a knife. Volar incisions are made. Meticulous defatting is performed protecting the neurovascular bundles (Fig. 3). The interdigital nerve is split if necessary. Wounds are closed at mid-lateral lines using 6-0 absorbable sutures attaching the distal edge of the dorsal hexagonal flap to the palm first (Fig. 3). Excess skin from the flap or the edges of the palmar incision can be used as a free skin graft if necessary. Tourniquet is deflated either before or after closing the wounds according to the surgeons’ preference. A silicone mesh is placed on the wounds, and a soft hand dressing is applied. Dressings are removed by the surgeon at 10–14 days after surgery. Wound therapy is started at 3 weeks from surgery by an occupational therapist and ended when there is no further activity in the scaring process.

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Fig. 2.
Fig. 2.:
Surgical incisions and site for skin graft. The specific geometric measures for the dorsal hexagonal skin flap are based on the interspace of the knuckles of the fingers to be separated: the distance measured between the midpoints of the knuckles is the same as the height of the flap as well as the distal width (BC). AD = 2 × BC. *Can be used as a skin graft.


None of the patients were lost to FU, with a mean FU of 1.3 years (range, 0.5–3.7). Surgery time per web space and level of syndactyly was as follows: in CC, mean 96 minutes (range, 72–123); in C, 129 minutes (range, 116–151); in SC, 91 minutes (range, 56–135); and in SI, 76 minutes (range, 50–95). There were no differences in the time between SI proximal interphalangeal joint and DIP level releases. Inguinal skin grafts were needed in 2 patients, and excess skin from the web reconstruction site was used to cover small distal defects in 5 patients. One bilateral postoperative infection occurred 7 days after surgery (patient 19) due to patient-related reasons (contaminated his dressings in a toilet bowl). The infection was treated with oral cephalexin for 5 days. The same patient later developed excessive scaring and web creep on the right side. Two separate patients developed scar hypertrophy and received treatment with silicone sleeves for the fingers and silicone sheets for the web spaces (patients 8 and 11). Mean web space height using the grade by Withey et al18 was 0.5 (range, 0–2). At last FU, one patient reported slight feeling of dryness in the web space area (patient 1). Twenty-five of 26 patients’ parents answered the VAS questionnaire. Mean cosmetic and functional VAS scores were 87 (52–100) and 92 (63–100), respectively, at last FU (Table 1 and Figs. 4–7).


In the early 1800s, webbed digits were separated with scissors in the nursery, which created 2 raw surfaces on the opposing fingers that healed by epithelialization and apparently lead to flexion contractures.1 In the mid 1800s, Didot popularized his technique of separating fingers with straight flaps with alternating midline incision on the dorsal and palmar side without grafting, which also lead to flexion contractures.20 In the mid 1900s, Cronin21 and Webster22 reported that flexion contractures did not develop if webbed fingers were separated with zigzag incisions and skin grafts. This principle has been adopted by most surgeons, and many modifications of the technique have been reported. Pigmentation and scarring of the grafts lead to development of defatting techniques and metacarpal advancement flaps to facilitate closing the wounds without grafts.9,22,23 The most commonly used technique with interdigitating zigzag flaps often leaves a cosmetically unpleasing prominent scar due to mismatch between palmar and dorsal skin texture and color. Fearon24 separated syndactylies in 43 Apert hands and feet by straight-line incisions without the development of flexion contractures. What role the lack of proximal interphalangeal joint plays in these results is unclear; however, Fearon24 reported no scar contractures in non-Apert syndactylies treated with the same technique. Sharma et al11 separated 14 fingers in 7 patients (2 syndromic) using longitudinal incisions and a triangular metacarpal advancement flap with functionally and esthetically pleasing results, but they failed to report the level of separated webs in nonsyndromic hands. Wang et al16 have recently reported a series of 16 web reconstructions using a hexagonal metacarpal advancement flap with zigzag incisions, yielding satisfactory results in 12- to 34-month FU. We used the same technique since 2003 but developed it further to straight incisions that leave the scars in the mid-lateral line in combination with the hexagonal metacarpal advancement flap to reconstruct the web.

The operative time of syndactyly separation depends on the extent and type of syndactyly, as well as on the surgical technique. The length of surgery using zigzag incisions and full-thickness skin grafts combined with web reconstruction with commissural dorsal flap varied from 40 to 120 minutes in a series of 39 patients, with mean operative times of 68 minutes in SI, 95 minutes in SC, and 98 minutes in C syndactyly.25 The reported length of simple syndactyly separation without skin grafts with metacarpal advancement flaps and zigzag incisions is shorter ranging between 44 and 86 minutes.8,16,26 In our series, separation of SI syndactyly lasted for just over an hour, in most SC and CC syndactylies, it lasted for <2 hours and in C syndactyly, slightly longer, which is quite close to the reported operation times with other graftless techniques.

Postoperative infections after syndactyly release with full-thickness skin grafts occurred in 3% of the 144 syndactyly webs treated by Barabás and Pickford.27 The risk of a postoperative infection was reported to be higher in 2 series using graftless techniques where 1/16 and 4/19 patients developed an infection.10,13 No reoperations were performed in patients with skin grafts, whereas all 5 patients who developed an infection after syndactyly release without skin grafts were operated on again. On the contrary from this, Ekerot26 found there to be more reoperations due to complications when comparing a procedure using full-thickness skin grafts (12/32 webs reoperated) to a graftless technique (2/28 webs reoperated). One of our 20 patients developed a bilateral self-induced infection that healed with oral antibiotics but later developed bilateral web creep that was successfully treated with a reoperation.

Web creep is the most common complication after syndactyly release usually appearing within 3 years after surgery, with a reported incidence of up to 60%.3,14,28 Postoperative infections and partial skin graft loss can lead to web creep, in which risk appears to vary also between different web reconstruction techniques.25,27,28 Age at the time of surgery does not seem to correlate with the risk of web creep,25,27 which seems to be similar in patients treated with (4%–30%) or without (3%–24%) skin grafts.7,8,25,26,28–32 Reliable comparison is, however, difficult because the number of patient types of syndactyly, FU rates and grading systems vary. Web height has been assessed by comparing it to the adjacent normal web, using the palmar crease as a reference point30,33 and with the 5-point grading system developed by Withey et al.18 The reported mean web height using the classification by Withey et al18 after syndactyly surgery has varied from 1 to 1.412,13. Our results are better than those in the earlier reports, but our FU time might still be too short.

Cronin20 reported in 1956 in 11 patients that longitudinal incisions crossing flexor creases to separate webbed fingers lead to flexion contractures in all cases. The reported risk of scar contractures is 0%–26% and of scar hypertrophy is 3.5% with techniques using zigzag incisions and skin grafts.27,28,31 It has, however, been suggested that zigzag incisions and skin grafts lead to conspicuous scars.35 The risk of scar contractures (0%–6%) or hypertrophy seem to be lower with graftless techniques,7,8,10,16 which is in accordance to our findings so far with no scar contractures and 2/30 hypertrophic scars that responded well to silicone treatment.

Subjective functional and esthetic results of syndactyly surgery are unfortunately often reported without using any specific outcome measurements.8,10,11,25 Furthermore, long-term outcome of syndactyly separation is also poorly documented usually with low FU rates (14%–32%) and small number of patients (24 webs).13,29 Hair growth from full-thickness skin grafts appears to be the most common problem, and minor cold intolerance is experienced by some patients. Mean functional VAS scores of 91–98 (range, 7–100) and mean cosmetic VAS scores of 79 (range, 38–100) have been reported. Discoloring and abnormal hair growth can be avoided with our new technique because skin grafts from the groin or forearm are rarely needed. Our subjective findings, representing parents’ opinion, are similar to the earlier findings that functional outcome is perceived better than the cosmetic.

Due to excellent short-term results, we chose to publish our technique earlier than anticipated. We will, however, continue with the study according to protocol and aim to measure the web space also using the method by Tonkin et al34 at last FU and report results of all aspects of the assessment method by Withey et al.18


Web reconstruction using a hexagonal dorsal skin flap and finger separation using straight midline incisions that close at the mid-lateral line is safe with good cosmetic and functional outcome in short-term FU.

Fig. 3.
Fig. 3.:
Defatting and skin closure. A, Hexagonal flap raised and dorsal defatting. B and C, Defatting from volar side and removal of the excess fat in one piece dorsally. D–F, Wound closure with absorbable sutures.
Fig. 4.
Fig. 4.:
Patient 1: simple incomplete syndactyly 3 years after surgery. A, View from dorsal side. B, View from palmar side.
Fig. 5.
Fig. 5.:
Patient 5: simple complete syndactyly 2 years after surgery. A, View from dorsal side. B, View from palmar side.
Fig. 6.
Fig. 6.:
Patient 22: complex (right hand) and complicated (left hand) syndactyly 6 months after surgery. A, View from dorsal side. B, View from palmar side.
Fig. 7.
Fig. 7.:
Patient 25, complicated (right hand) and SI PIP (left hand) syndactyly six months after first surgery (A and B). Same patient three weeks after second surgery (C and D). The last separation is not included in our results as the follow-up is too short.


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Copyright © 2020 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The American Society of Plastic Surgeons.