Mr Dalvi Humzah and Anna Baker detail the anatomy of the hand and how to successfully augment the area
The appearance of the hands, in conjunction with the face and neck, are the most conspicuous parts of the body. In our opinion, the anatomy of the ageing hand has, historically, been poorly conveyed, as more emphasis seems to have been placed on describing the palmar aspect. In our research, there are only a few reports within the literature that describe the dorsal region in relation to technical considerations when rejuvenating.
The practitioner is able to employ a number of rejuvenation strategies to improve the ageing changes of the dorsum of the hand; the safety and effectiveness of these techniques is determined by: an accurate clinical assessment, use of the most suitable treatment, and a sound technique to perform the chosen modality. In order to augment this area safely and to minimise risk of complication(s), a thorough understanding of the anatomy of this complex region is imperative. Practitioners must also ensure that they have a detailed understanding of the characteristics of available products when considering non-surgical rejuvenation of the dorsum of the hand.
Clinical studies continue to emerge, analysing the effectiveness of different modalities, including combination treatments. In this article, we shall address some of the studies’ findings and discuss the anatomy of the dorsal hand in conjunction with a preferred method of non-surgical augmentation.
Ageing of the dorsum of the hand may be characterised by large intermetacarpal spaces, skin atrophy, dryness, uneven skin tone and solar lentigines, purpura as well as actinic keratosis
A youthful hand comprises smooth, hydrated and firm skin without the presence of visible veins, tendons, or textural changes.1 Hand ageing is a three-dimensional process that involves the bones, soft tissues and skin.2 Ageing of the dorsum of the hand may be characterised by large intermetacarpal spaces, skin atrophy, dryness, uneven skin tone and solar lentigines, purpura as well as actinic keratosis.3 Many of these develop owing to extrinsic factors; yet, some are intrinsically induced through disease processes (arthritic symptoms) as well as bone and soft tissue remodelling. As a consequence, the demand for correcting these changes has been steadily increasing within the last 10 years.4
Options to improve texture and pigment changes can include chemical peels, photodynamic therapy, intense pulsed light as well as lasers.2,3,5 Volume loss may be counteracted through a variety of injectable agents including hyaluronic acid, calcium hydroxylapatite, poly-l-lactic acid and autologous fat.1,3,4,6,7 An ideal injectable substance to contour the dorsum of the hand should be durable to withstand dynamic demand, as well as mouldable with good longevity.8
There are key anatomical concepts regarding the anatomy of the dorsum of the hand, which includes the skin, soft tissue, areolar tissue/dorsal laminae as well as intrinsic muscle activity and wasting.9 Bidec et al performed detailed histological and ultrasound analysis of cadaveric hands, in which the authors identified three layers of fat, separated by three facial layers.10 The superficial layer is the first and is located between the dermis and the dorsal superficial fascia which does not contain structures and, in an aged hand, may be adherent to the deep dermis.
The intermediate fat layer resides between the dorsal superficial fascia and the dorsal intermediate fascia, which is also an extension of the antebrachial fascia of the forearm. The intermediate layer contains the dorsal veins and sensory nerves. The deepest and final fat plane is located between the dorsal intermediate fascia and the dorsal deep fascia, which covers the interosseous muscles and the metacarpal bones. The extensor tendons are located between the dorsal intermediate fascia and the dorsal deep fascia. There is potential communication between the palmar and dorsal vessels through perforators, which pass through the interosseous spaces,11 which lead to the end arteries in the digits. Therefore there is potential for material injected in the dorsum to pass by a retrograde mechanism into the palmar circulation and enter the end artery of the digits.12 In addition, Bidec et al report findings of vertically arranged fibres which transition between the layers from the deep compartments to the dermis, which house the perforating vessels that supply the subdermal plexus from the deep dorsal vessels. Injury to these vessels during cosmetic injection may be the cause of bleeding and bruising.12
To treat the dorsal aspect of the hand safely, it is crucial to identify the presence of any veins and tendons and to mark these, if necessary
To minimise the risk of potentially serious complications, the practitioner must understand the complexity and variability of the dorsal arterial system.13 The dorsal carpal arch is formed by the carpal branches of ulnar and radial arteries, from which dorsal metacarpal arteries arise distally in the intermetacarpal spaces.13
The dermis and epidermis of the dorsal hand are exceptionally thin with a reduced number of pilosebaceous units in comparison to facial skin.3 Lefebvre et al describe ultrasonographic findings to indicate that the thickness of the dermis has been shown to be between 0.2 to 0.9mm, the fascial plane from 0.3 to 2.2mm and tendon layer from 0.7 to 1.7mm; an approximate total thickness of all layers equals between 2.2 and 4.6mm, which are key measurements in the context of selecting an appropriate plane for injection.4 Aesthetic assessment scales may be a useful tool during the consultation to establish the extent of correction and to manage realistic expectations from treatment.14 To treat the dorsal aspect of the hand safely, it is crucial to identify the presence of any veins and tendons and to mark these, if necessary. An assessment of the motor and sensory activity of the palmar region of the median, radial and ulnar nerves, should be performed. In addition, the arterial supply should also be assessed by utilising the Allen test.15 To assess, the patient is asked to make a fist for approximately five to eight seconds, with pressure applied over the radial and ulnar arteries to occlude them. The hand is then relaxed and opened, which should be pale, as the pressure over the ulnar artery is released and the colour should return within seconds to verify that the ulnar artery is patent. Equally this test can be repeated with pressure over the radial artery.15
In line with all dermal filler treatments, a strict aseptic technique when augmenting the dorsum of the hand is imperative in light of the close communication of the compartmental spaces of the hand.16 While it is accepted that product may be placed safely within the dorsal superficial layer lamina; in an aged hand, it can be too close to the dermis to separate and would be unsuitable for the placement of calcium hydroxylapatite and hyaluronic acid as these would be visible through the skin. Lefebvre et al (2015) consider that raising the skin between two fingers (tenting), prior to injecting a bolus of dermal filler results in the product being placed in the intermediate plane. This may be due to the tight dermofascial adhesions, whereby the skin and fascia lift together. ‘Tenting’ may not create sufficient space for the product to reside and a needle approach may easily perforate fascia and veins.4
Our preferred product choice for dorsal hand volumisation is calcium hydroxylapatite owing to its viscoelastic properties, Food and Drug Administration approval and longevity
Vessels enlarge from a distal to proximal direction and are more visible proximally; as such may be avoided through proximal injection points.5 Insertion of a cannula and product proximally (at the level of the wrist) is unlikely to damage the dorsal arteries; yet, distal injections to the extensor digitorum communis could damage the perforator vessels, and it is possible for a product to be injected into these vessels, as they have a communication with the palmar and end artery digital vessels. The findings of Lefebvre et al in cadaveric studies suggested that a safe plane for product placement is between the dermis and fascial layer, using either a 22G or 25G, 38mm or 50mm cannula approach, creating a subdermal space for injection.4 Used appropriately, a cannula is less likely to perforate vessels or fascia to ensure that product remains within the desired plane.17
Our preferred product choice for dorsal hand volumisation is calcium hydroxylapatite owing to its viscoelastic properties, Food and Drug Administration approval and longevity.18 The patient’s hands are initially washed to get the area socially clean and then the dorsal surface cleaned with an approved skin antiseptic agent, such as chlorhexidine. Retrograde threads (through a proximal insertion point) may be placed to achieve the desired level of correction. To locate the subdermal plane, the undersurface of the dermis is scraped with the cannula, which appears as ‘tethering’ on the surface of the skin as the cannula is passed through this plane. After correction, the product is massaged gently to ensure even distribution and the patient is advised to keep their hands clean and dry following treatment, to avoid wearing any creams and abstaining from vigorous activity for 48 hours.
It is imperative for practitioners to have a sound knowledge of the ageing changes of the dermis, deeper tissues, muscles and bony structures of the hand. Knowing the position of the perforating vessels and how the dermis is vascularised will reduce the possibility of retrograde injection into the palmer circulation and minimise the risk of bruising. Anatomical literature continues to advance in relation to non-surgical rejuvenation strategies and practitioners are advised to be aware of published studies. The use of aesthetic scales is a valuable tool to assess the pre-treatment condition and the predicted degree of correction. This will enable patients and practitioners to discuss the realistic expectations regarding the possible outcomes of treatment.
Mr Dalvi Humzah will discuss periobital, perioral, mid-face and lower face anatomy and enhancing the eye at the Aesthetics Conference and Exhibition 2016. Anna Baker will also discuss the forehead, temple and brow. Visit www.aestheticsconference.com/programme to find out more.