Modified Z-Plasty for Reconstruction of Webbed Scar Contractures ()
1. Introduction
Webbing is the skin and soft tissue linking the entire path up the digits. The distal end of the web space reaches the middle of the proximal phalanx, on the same plane as the volar skin, and forms an inclined plane with the dorsal skin. The normal rhombus network structure of the web between the fingers is the prerequisite for adduction, abduction, arbitrary flexion and extension [1] .
The hand is a part with various tissues, joints and functions. Without scientific and appropriate treatment, second-degree burns of the hand often leave a scar and even result in contracture, which affects hand function and dexterity. Postburn contractures can lead to deformities [2] . Due to the lack of soft tissue near the contracture area, scar revision surgery, including release and defect repair, is a challenging problem.
The webbed scar of the crotch joint was released as usual using a continuous standard Z-plasty [3] [4] . The standard 5-flap Z-plasty has some limitations, such as a limited degree of scar release and extension and prolonged operative duration. At the same time, the mobilization of organizations is limited. The modified Z-plasty is an effective technique to prevent the above problems.
2. Materials and Methods
Thirty-two patients enrolled from 2018 to 2022 with joint scar contracture deformity, with a mean age of 32.5 years, were included in the study. The same surgeon, who strictly controlled the indications, performed all operations. All patients underwent incisionor resection and modified Z-plasty of the scar under anesthesia. The patients suffered from contracture of the hand for at least one year, which was localized in web spaces, flexor surfaces of the digits, broad palm and extensor surfaces of the hand. The severity of contracture is classified as mild as the scar moderately restricts certain hand movements, and adequate soft tissue, according to the algorithm for releasing burn contractures described by Hudson and Renshaw [5] .
2.1. Surgical Approach
In terms of design, there are some anatomical landmarks to be addressed: the arch of the normal interdigital spaces, which is the line of articulatio metacarpophalangeal’s horizontal stripes, is called the basic line (BL). The highest point of the web space scar was designed as B and the lowest as C, taking BC as the middle arm, AB = BC = CD. Point A is on the dorsal side. Points C and D are on the volar side (Figure 1). When the flap (A-B-C) is turned to the dorsal palmar side, point B is fixed, and point A is switched with points C and D (Figure 2). The Angle between ABC is 30 to 45 degrees and BCD is 90 degrees. The shaded tissue needs to be excised to avoid affecting flap transposition (Figure 3).
1) Concerning scar blood vessel density, the dorsal palmar scar tissueshould be at least tendernessor pliable according to the modified VSS (Vancouver Scar Scale) [6] .
2) In some cases, the design needs to be changed slightly, which is when the metacarpophalangeal joint (MCP) is extended and flexed; it is guided by skin activity.
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Figure 1. The highest point of the web space scar was designed as B and the lowest as C, taking BC as the middle arm, AB = BC = CD. Point A is on the dorsal side; points C and D are on the volar side.
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Figure 2. Point B is fixed, and point A is switched with point C and D.
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Figure 3. The shaded tissue needs to be excised to avoid affecting flap transposition.
A tourniquet was placed on the upper arm near the axilla to prevent intraoperative bleeding from affecting the operation. The incision was made toward A-B-C-D, and the skin and subcutaneous fascia were opened. Carefully separate the fascia layer to avoid finger blood vessels and nerve damage. Cut through the scar tissue. Haemostasis is achieved using bipolar electrocautery. Moving the flap, point B was transferred to point D, and point C was transferred to point A, and fixed with 5-0 Puling suture. The shape of the flap after transposition like reverse z-shape (Figure 4).
2.2. Postoperative Treatment
The wound was covered with a light dressing for three days. Remove blood scabs and secretions carefully during dressing change. Sutures were removed 12 - 14 days after surgery. After the sutures were removed, anti-scar treatment was performed for over half a year.
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Figure 4. The shape of the flap after transposition.
3. Results
Our technique was applied to 32 patients (mostly in the upper limb) with burn contracture in the following areas: neck (5 cases), axilla (10 cases), forebreast (3 cases), thigh (2 cases), and hand (12 cases).The mean operative time for a webbed scar on the hand and other joint areas was 15 minutes and 30 minutes, respectively.
The postoperative results are shown in Figure 5. Sutures were removed 7 days after neck surgery, 10 days after thoracic surgery, and 12 - 14 days after limb surgery. All wounds healed well, no skin congestion, necrosis or other complications, and postoperative scar contracture was satisfactorily relieved. However, we failed to contact patients for long-term follow-up.
4. Discussion
The joint is an important fulcrum for the limb to maintain good function [7] . First, the most crutial function of joints is movement, and every joint of the human body is inseparable from movement. Second, joints act as a buffer against force. Third, joints are designed to withstand gravity, supporting weight and other stresses. Fourth, the joint can act as pivots and form a lever in the human body’s activities [8] .
Burns, scalds or wounds across joints may cause a hypertrophic scar or contracture scar, which may affect joint function. Webbing of scar mostly develops from the cross-joint area and requires surgery to release the tension. Webbed scar revision surgery should be performed until the scar matures and softens, which can be over half a year or longer. This can ensure the best possible surgical outcomes. Especially for the burn syndactyly, the web-space scar has little impact on the flexion and extension of the finger, making it possible to wait longer.
Examining the donor scar to understand what may be underneath it is very important. The Vancouver Scar Scale is an effective method to evaluate the condition of the scar, especially in evaluating treatment effects [9] .The more flexible the scar tissue, the greater it is potential to repair all components of the interphalangeal joints: its depth, shape, groove, and inclination to the metacarpal head.
The finger blood supply is abundant due to the modification of the Z-plasty, which has a larger Angle (the minimum angle is greater than 30 degrees), providing a reliable blood supply and avoiding necrosis of the tissue flap. If the local
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Figure 5. Comparison between preoperative and postoperative contracture deformity of the web space between the fourth and fifth fingers.
flap angle is less than 30 degrees, the probability of flap necrosis increases [10] [11] .
Most of the mature webbed scars were repaired by Z-plasty, multiple Z-plastics in series or the 5-flap technique. However, due to the limitation of the included angle and the force of tension, the length of the prolonged scar is limited, so the conventional Z-plasty is ineffective in treating a webbed scar. The greater the angle of the outer arm of the Z-plasty, the longer the extension of the middle arm. The angle between the outer arms is 30 degrees, and the middle arm is extended by 25%, 60 degrees is 75%, and 90 degrees is 120% [12] .
5. Conclusion
The modified Z-plasty has a larger angle, more surrounding scar tissue is mobilized, the postoperative scar tissue is released, and the recurrence probability is negligible. Moreover, the operative time is significantly reduced due to the single Z-plasty. With a large angle, a flap has a sufficient blood supply. The flap is oblique in design. The adjacent fingers do not interfere with each other, which is suitable for the simultaneous operations of multiple fingers.
NOTES
*Xinfeng Huang and Jiaqi Xu contributedly qually to the paper.
#Corresponding author.