Tang Ho, MD
The reconstruction of a subtotal to total lower lip defect, whether it be due to trauma or cancer resection, presents a significant challenge for the plastic and reconstructive surgeon. In addition to the clear immediate need for soft tissue coverage, there is also the challenge of re-establishing oral competence and function. The lower lip serves an important function not only in deglutination, speech production, but also allows the expression of emotion.
When the lower lip defect size is less than one-third of the lip, primary closure is possible and usually provides the best cosmetic and functional outcome. Larger medium-sized defects can usually be reconstructed with some type of cross-lip flap such as Abbe and Estlander, depending on whether the oral commissure is involved. Larger defects but less than a subtotal or total lip defect can often be reconstructed with variations of the classic Karapandzic, Gillies fan, or Bernard-Burow flaps. These local flap reconstructive options utilize a combination of advancement, rotation, and cross-lip flaps. Common to all these local flap procedures is the issue of post-operative microstomia, which can create significant functional morbidity and aesthetic deformity.
In reconstructing subtotal or total lower lip defect, some type of distant tissue transfer often needs to be considered. The use of distal pedicled flaps — including deltopectoral, sternocleidomastoid, and pectoralis myocutaneous flaps — have all been described. However, with the improvement in microvascular free tissue transfer techniques, free flaps have become an important available option to consider.
Sakai et al introduced the concept of total lower lip and chin reconstruction with a composite radial forearm–palmaris longus tendon free flap two decades ago.1 The radial forearm free flap is ideal for lower lip reconstruction because of its contour pliability and also its long pedicle length.2 The lateral antebrachial cutaneous nerve can be incorporated to provide neurotization of the flap and create a sensate neolip/chin.3 The incorporation of the palmaris longus tendon allows suspension and contouring of the flap to re-create the oral sphincter.4 Palmaris longus tendon is one of three wrist flexors, and its sacrifice creates minimal functional morbidity. However, palmaris longus tendon has been reported to be absent in up to 15% of the Caucasian population. In the case where palmaris longus tendon is absent, the flexor carpi radialis tendon can be incorporated into the flap instead.5
Perhaps the most challenging aspect of total lower lip reconstruction with the composite radial forearm flap is where and how much tension to inset the palmaris longus tendon sling. Suspending the flap with too much tension on the palmaris longus tendon creates lip entropion, while insufficient tension results in lip ectropion and oral competency issues. Although it is not a dynamic reconstruction, the suspension of the palmaris longus sling onto the modiolus with adequate tension does allow transmission of extrinsic facial muscle action to the neolip.6 Since its introduction there have been refinements to the reconstruction technique with the composite radial forearm flap. There have been reports of suspending the palmaris longus tendon to the malar prominence or the upper lip.7
For optimal aesthetic outcome, secondary commissuroplasty may be required at a later date. The lip vermillion can be reconstructed at the time of the primary procedure either with a tongue or buccal mucosal flap. However, this does create some risk to the viability of the free flap. Alternatively this can be done as a staged procedure or instead with medical tattooing. Post-operative flap edema is not unusual and can take up to 3–4 months to resolve.