Unilateral cleft lip is a complex congenital anomaly that occurs when the upper lip and nasal structures fail to fuse during embryonic development. This defect affects not only the facial appearance but also the function of the lip, nose, and maxilla. Surgical correction of cleft lip is usually performed in infancy to restore the normal anatomy and functionality of the affected structures, as well as to enhance the psychological and social well-being of both the patient and their family. Surgical repair of unilateral cleft lip is typically performed within the first few months of life to improve facial appearance and function and to prevent social stigma and psychological distress. The goal of surgery is to achieve a symmetric, functional, and esthetically pleasing lip contour, vermilion border, and nasal structure. Surgical techniques for unilateral cleft lip repair have evolved significantly over the past few decades, and the current approach is based on a combination of individualized planning, careful tissue manipulation, and meticulous surgical technique. Historically, several techniques have been developed for cleft lip repair, including the Millard rotation-advancement technique, Tennison-Randall technique, and triangular flap technique [1-4]. Each technique has its advantages and disadvantages, and the choice of technique depends on the severity and complexity of the cleft, the surgeon’s experience and preference, and the patient’s individual characteristics and goals. In recent years, several advances have been made in the field of cleft lip repair, including new surgical techniques and approaches. This review provides an overview of the current concepts and surgical techniques in unilateral cleft lip repair.

In patients with cleft lip, it is crucial to restore the normal structure of the lips, necessitating a thorough understanding of their anatomical features. The upper lip consists of the vermilion and white lip, featuring keratinized epithelium in the front and non-keratinized oral mucosa in the back. The tubercle is the central part of the vermilion, while the vertical area extending to the nose is known as the philtrum. The philtrum is a structure created by the intersection of the orbicularis oris muscle and is bordered by two vertical pillars. The upper lip is divided into the vermilion and white lip by the vermilion border, and the hairless area that blends with the white color above this border is referred to as the white roll [5]. The orbicularis oris muscle serves two functions: retracting the lips using the surface layer of muscle fibers and closing the oral sphincter with the deeper layers of muscle fibers. At the marginal part of the vermilion, the orbicularis oris muscle becomes shallow and concave, helping to maintain the natural shape of the lips.

Depending on the extent of the cleft, various changes can occur in the skin, muscle layer, and internal skeleton. In a complete cleft lip, the muscle fibers of the orbicularis oris muscle in the outer lip segment run horizontally toward the midline, then rise along the edge of the cleft to attach to the nostril sill, alar base, and pyriform aperture. The orbicularis oris muscle fibers in the inner lip segment also converge toward the midline and either attach to the periosteum of the upper jawbone at the alar base or become discontinuous in the subcutaneous tissue layer at the philtrum. In an incomplete cleft lip, if there is an absence of a skin bridge that is approximately one-third the length of the upper lip, the orbicularis oris muscle fibers in the outer and inner lip segments may not be continuous. Although a microform cleft lip has skin continuity, the continuity of the muscle layer beneath the skin groove may be disrupted.

The skin of the philtrum lacks hair and sweat glands. The red lips converge in an area where the lip segments split, and the lips are generally narrow on the inside and either wider or narrower on the outside. Regarding blood supply, the superior labial artery runs parallel to the fissure’s edge in the outer lip segment and connects to either the angular artery or the lateral nasal artery. In the inner lip segment, the superior labial artery ascends through the fissure and connects to the posterior septal artery.

It is commonly believed that variations in unilateral cleft lip are present only on the affected side. However, a 2021 study by Tse et al. [6] demonstrated that variations exist on both sides. For example, in patients with unilateral cleft lip, the philtral area on the affected side is displaced to the opposite side, aligning with the position of the maxilla. Additionally, the alar base on the non-affected side is positioned more superiorly and laterally compared to the affected side. Consequently, when treating unilateral cleft lip, it is essential to consider deformities on both the affected and non-affected sides. Gaining an accurate understanding of the changes in the non-cleft side prior to surgery is crucial.

Corrective surgery prior to unilateral cleft lip repair aims to minimize skeletal and soft tissue deformities, converting the cleft lip from a complete to an incomplete type. Common preoperative correction techniques include lip taping, silicone conformers, lip-nose adhesion, the Latham device, and nasoalveolar molding.

Lip taping and silicone conformers can be applied immediately after birth. Taping is applied to both cheeks to promote the fusion of separated segments and to decrease tension between tissues during primary surgery [7]. Silicone conformers take advantage of the plasticity of newborn cartilage to lift and reshape deformed nasal cartilage, and can be used in cases of incomplete clefts with nasal floor deficiency [8]. Lip-nose adhesion is another method for correcting incomplete cleft lip, typically performed before the age of 2 to 3 months [9]. This technique involves filling the gap in the upper lip and the cleft in the alveolus, effectively converting a complete cleft lip into an incomplete one. The position of the maxillary arch and nasal cartilage can be adjusted using a rectangular skin flap originating from the edges of the cleft. While this method can help reduce tissue tension before primary surgery, it is not commonly used due to the scarring and abnormal adhesion of the nose that may result from the surgery (Fig. 1).

The Latham device is an active preoperative orthopedic device used to correct unilateral cleft lip and palate [10,11]. It comprises an adjustable screw-type framework affixed to the maxillary arch, which serves to correct the premaxilla’s displacement. This device is engineered to exert a gentle force that repositions the premaxilla to the midline and enhances the alignment of the alveolar ridges prior to primary lip surgery. The correction process entails weekly adjustments of the device by the child’s caregiver, under the supervision of a medical professional. Although the Latham device has been deemed highly effective in ameliorating the alignment of the alveolar ridges and mitigating the severity of the cleft deformity, its usage has waned in recent years due to its potential impact on facial growth, particularly on maxillary development. Moreover, the implementation of the device necessitates a minor surgical procedure to fix it in place, which may cause discomfort and inconvenience for the child and their family.

Nasoalveolar molding is a technique utilized for treating unilateral cleft lip and palate (Fig. 2). This method can lessen the severity of the cleft deformity, enhance the symmetry of the nose and lip, and reduce the necessity for extensive surgical intervention during primary repair. The technique involves the use of a custom-made oral appliance worn by the infant to preoperatively mold the nasal and alveolar structures. This appliance comprises a nasal stent and a plate that covers the cleft in the gum. Nasoalveolar molding treatment is typically initiated within the first few days following birth and continues until the primary lip repair, which is usually performed around 3 months of age. Studies have revealed that employing nasoalveolar molding can lead to improved esthetic outcomes and fewer surgical procedures for children with cleft lip and palate compared to other techniques [12,13]. However, it requires a high level of expertise from the healthcare team and commitment from the parents to follow the treatment protocol.

Surgical treatments for unilateral cleft lip and palate aim to correct lip and nose deformities, restore symmetry, and promote normal midface growth in the long term. Patients present with a variety of anatomical deformities that necessitate individualized approaches. The size of the cleft and the presence of syndromes also impact the selection of surgical techniques. Regardless of the chosen surgical technique, the primary objective is to achieve equal lip height between the cleft and non-cleft sides. Numerous cleft lip and nose repair designs have been proposed by several prominent surgeons (Fig. 3).

A previous study reported that over half of American cleft palate-craniofacial surgeons currently perform some form of primary nasal correction in patients with unilateral cleft lip [23]. However, the selection of appropriate techniques has been a topic of extensive debate, leading to significant variation in the timing, techniques, and extent of correction during cleft rhinoplasty [24-27]. Data on preferred techniques for primary cleft rhinoplasty reveal inconsistent management of the lower lateral cartilage [25]. Most surgeons reported consistently dissecting the alar cartilage, but only one-third of respondents relied on suture fixation of the alar cartilage. The challenges of manipulating infantile nasal cartilage, which is inherently thin and pliable, may deter surgeons from placing intercartilaginous sutures.

In primary cleft rhinoplasty, the alar cartilages are regarded as the crucial elements requiring correction. Berkeley was the first to suggest direct repositioning of the alar cartilages [28]. He accomplished this during primary labial repair by placing a horizontal mattress suture between the cartilages through an external skin incision [28]. McComb [29] is notable as a significant advocate for cartilage repositioning. He performed a more extensive correction of the nose by elevating the alar cartilage and shortening the cleft side hemi-nose. The scope of nasal skin dissection extended from the alar rim over the nasal tip and up to the nasion on the cleft side nose, without an intranasal incision. The alar cartilage was elevated by placing a long mattress suture between the nasal vestibule, through the intercrural angle and lateral crus, and up to the nasal skeleton at the nasion. This surgical technique for nasal dissection, alar elevation, and stabilization was embraced by proponents of primary nasal correction. Meanwhile, additional incisions, such as the reverse U, infracartilaginous, and intercartilaginous incisions, were employed to access the alar cartilages [17,30,31].

Several authors have reported new techniques for alar cartilage repositioning to facilitate procedures and enhance the accuracy of suspension. Kernahan et al. [32] performed primary rhinoplasty using modified Tajima methods and developed a Senn retractor with an open center to grasp a double-armed suture intranasally, placing it in the contralateral upper lateral cartilage [33]. This allowed the suture to be pulled out of the cleft side nostril when the retractor was withdrawn. Rottgers and Jiang [34] employed a hollow needle to place a suspension suture between the contralateral upper lateral cartilage and the cleft side lower lateral cartilage.

Cartilage correction surgery via a semi-open rhinoplasty involves the following steps: (1) employing a semi-open approach through an incision on the edge; (2) gently peeling the surface of the non-irritating cartilage; (3) suspending the dome area of the non-irritating cartilage for repositioning; and (4) threading a needle through the supralateral cartilage and then through the non-septum. At this point, the needle tip is pulled out until the marked section, allowing the suture material to be embedded. (5) After suturing the cartilage, the non-mucosal incision is stitched, and (6) quilting sutures are performed in the non-irritating and non-cartilaginous areas to ensure there is no dead space surrounding the non-irritating cartilage.

In a related context, the author introduced a novel surgical technique based on the semi-open rhinoplasty approach through a marginal incision in the cleft side nostril (Fig. 13). The author’s method employs a specially designed needle (Chang’s needle, HansBioMed Corp.) to simplify the placement of an intercartilaginous suture between the lower and upper lateral cartilages. Dissection extends across the nasal envelope overlying the dome of the alar cartilage and the nasal tip, creating space for the intercartilaginous suture. Using Chang’s needle with a 5-0 polypropylene thread, the dome of the alar cartilage is sutured, and the needle is directed medially and cranially, piercing through the septal and contralateral upper lateral cartilages. The needle is then withdrawn from the skin until the laser mark is visible and reinserted into the intranasal side. Subsequently, an intercartilaginous suture is performed along the cleft side alar cartilage, septal cartilage, and contralateral upper lateral cartilage. This technique enables stable fixation between the cartilages without extensive subcutaneous undermining, preventing scar contracture and preserving growth potential. Representative cases are illustrated in Figs. 14 and 15.

Contemporary techniques for unilateral cleft lip repair aim to achieve three-dimensional anatomic and functional restoration of the affected structures. Various cleft lip repair techniques have been proposed, with some relying on precise anatomic geometry, while others allow for greater flexibility in design. Primary cleft rhinoplasty is currently considered an optimal technique, targeting the deformed lower lateral cartilages, septum, and nostril floor. The primary cheiloplasty and rhinoplasty techniques we describe herein have evolved over time, based on our extensive experience and lessons learned from previous generations of cleft surgeons who pursued optimal results. To achieve the best outcomes, cleft surgeons must adopt a comprehensive approach, with meticulous preoperative planning to determine the most suitable surgical approach for each individual patient.