Major Head and Neck Regions Using the Keystone Technique

Abstract

The Keystone flap allows one to close large soft tissue defects, even under an element of tension. The vascular supply comes from random perforators within the various dermatomal mark outs in the head and neck and this vascular source supports the subdermal plexus. Individual perforators are not itemised nor skeletonised and this surgical outline of the dermatome has been likened to a sympathectomy effect which produces a hypervascularity in the flap, again this supports reconstructive healing. Utilising these principles really is focusing back on the embryological mark outs of the dermatomes and this embryological basis is the basis for the vascular reliability on fascial island flaps.

Facial and smile lines are all respected which goes and contributes to the achievement of normal facial grimace and smile lines from the scalp, the forehead, nose and cheek and periorbital regions. These anatomical units are really dermatomal anatomical units in the Keystone application.

Plastic surgical textbooks have umpteen varieties of loco-regional flaps but that principle of islanding within the dermatomal precincts – which is sometimes only a dermal incision which is surgically closed in the reparative technique. Sometimes MAYO scissors allow the tissues to be stretched before the definitive closure and the subfascial units are thus stretched to facilitate dermal apposition while not disturbing the integrity of the contained vasculature. If there are elements of tensional lines in these closures, sometimes the realignment of the suture points will help to overcome this mild or temporary vascular impedance.

The single layer suture technique is the basis of its success when locking mattress sutures at the points of maximum tension are accompanied by remaining sutures to approximate the layers and the continuous nylon epidermal seal creates perfection in the healing wound  margin. The wound dressing technique needs supervision where the continuous nylon is cut at 7 days and the tension sutures remain in up to 3 weeks to avoid rupture.

The Keystone allows one to bypass standard loco-regional flaps including the Limberg which when looked at schematically is not dissimilar to the Keystone design but amplified by the use of a total island and supported by the subdermal plexus.

The Keystone bypasses the need for nasal/ethmoidal reconstruction without layered grafting over a bony defect as the mucosal lining of the remnant becomes the alternative mucosal replacement (that is why we do not graft tonsillectomy as mucosa regenerates).

Case 5 is a modification of the Bezier unit and jointing the diagonals of any Keystone creates a V-Y island flap.

Closure of parotid defects uses the cervico submental C2, C3 dermatomes and blunt dissected up to the base of the sternomastoid which becomes the focus of the rotation of the Keystone with cervical fascia to close the parotid defect. The apical sutures near the apex of the parotid defect are the tension sutures to maintain the reconstruction which warrant a long-term insertion should premature removal allow the wound to breakdown.

Residual swelling reduces in time with the recovery of cutaneous nerve supply but the reliability of the technique to be used in irradiated tissue is one of the lifelines for the Keystone reconstruction.

The timeframes for operating are shorter and elderly patients are off the table within an expeditious timeframe, eliminating another co-factor of anaesthetic morbidity in a 90 year old.

The advantage of the Keystone in the lower lip reconstruction, a mucosal bridge transfer where the direct apposition may cause a disturbance in clinical outcome when hair bearing tissue at the mouth follows a vermilionectomy.

Thus, the Keystone has universal applications in most areas of the head and neck whatever the age group, even with the restrictions of irradiated tissue.