10. Segmental aponeurectomy: surgical technique

10.1 Introduction

The basic postulate of segmental aponeurectomy is that, if we can create a permanent discontinuity in the retracted aponeurotic band without wide dissection of the fascia itself, then the retracted band from which tension has been eliminated will disappear or at least cease to act as a contracture (Moermans et al., 1984; Moermans, 1990, 1991). It has been amply demonstrated that this can happen in scar contracture (McGregor 1967, Flint 1990) and the idea has been extended to Dupuytren's disease (Watson, 1984; Gonzales, 1971, 1985; McGregor, 1985; Thurston, 1987). It is thus much more than a simple fasciotomy, since we create a gap in the retracted aponeurosis.

10.2 Surgical technique

10.2.1 Anaesthesia and haemostasis

The operation is carried out as an outpatient procedure. It is performed under pneumatic tourniquet and usually under regional intra-venous anaesthesia. Occasionally, in more severe cases, a block of the brachial plexus is required.

10.2.2 Incisions

Small curved skin incisions about 1.5 cm. long are made directly over the contracted band in the palm and, if necessary, in the fingers in such a way that if they were joined they would form a lazy S (fig. 1).

Figure 10-1: Planning of the small curved incisions

They should be planned to allow the excision of the nodules since, as we have seen, they certainly play a most significant role in the pathogenesis of the contracture. The placing of the incisions directly over the cords minimises the lateral undermining and therefore the size of skin flaps.

10.2.3 Dissection

As there is often no dissection plane between the fascia and the deep dermis (over the nodules, in the distal palm, this dissection plane never exists), the dissection between the skin and the contracted aponeurosis beneath must be carefully done, close to the dermis, to avoid, as much as possible, any bridge of pathological tissue. This also allows re-expansion of the skin even if it is severely pitted. While an assistant pulls on the finger to keep the contracted band under tension, small pieces of fascia about one centimetre long are excised, beginning proximally, without further skin undermining or wide dissection of the surrounding tissues. The fibro-fatty tissues are preserved especially in the distal palm. The segment of cord that will be excised should be fully dissected before division as earlier release of tension makes dissection more difficult.

At the base of the proximal phalanx, this excision is usually difficult because of the neurovascular bundles. To diminish the risk of damage of the digital nerves, it is always performed under maximum tension of the cord, never using scissors but only a scalpel blade to separate the tissues. Actually, this is not a cutting procedure because the cord is only gently scratched with the point of a N^o 15 blade kept at an angle. The grinding that can be heard and felt is a good guide to locate the digital nerve: when it stops, the nerve is just under the blade. This works because, in primary cases at least, the nerve is never involved in the disease process and there is always a free space between it and the cord. The nerve may be moved out of its normal anatomical position by a contracting band or it may appear to penetrate a Dupuytren's nodule but, if the matter is investigated closely, it will be found that by the careful approach just described it is almost always possible to preserve the neurovascular bundle. A good working knowledge of the three-dimensional anatomy of the fascia and of the contracture patterns is nevertheless essential and the operation should not be performed by a novice hand surgeon except for the less severe cases.

In the most difficult situations, if one feels that the risk of damaging the nerves is too high, it is always possible to join the small curved incisions to allow a better view of the palmar surface of the digit as in classical operations.

Certain anatomical relationships have been found to be useful during the operation:

in the mid-palm the neurovascular bundle will always lie deep to the transverse fibres of the palmar aponeurosis and these therefore act as a safe landmark; as these fibres extend as far distally as the distal palmar crease, it is possible to perform the dissection proximal to this skin crease without uncovering the neurovascular bundle; distally from the distal free edge of the transverse fibres, it is valuable to try to appreciate whether the cord is superficial to or in the same plane as the nerves
the system of natatory fibres is another safe surgical landmark as the nerve will lie deep to these; this is not always of value however as these fibres can be involved in the contracture with resulting distortion;
at the base of the middle phalanx, the transverse Grayson's ligaments provide a system of anchorage for the neurovascular bundle which is therefore likely to be held laterally in an undisplaced position.

The tense band is scratched through until a gratifying snapping sensation is not only felt but also heard. At this point, complete extension of the fingers is usually achieved. In some cases, a shortened volar joint capsule may restrict full extension of the P.I.P. joint but it is best mobilised post-operatively by splinting and not by capsulotomy or check-rein ligament release (Watson, 1979; Bowers, 1986) as the results with these procedures have always been disappointing. Prior to operation, the patient is always warned about the possibility of incomplete proximal interphalangeal joint release.

This operative approach fits in well with the three essential principles stated by Skoog (1967) and recently emphasised by McGrouther (1990d, 1990e):

preservation of the transverse fibres of the palmar aponeurosis that are kept intact to act as a safeguard in protecting the delicate anatomy of the deep palmar space; Skoog recognised that these transverse fibres were not involved in the disease although they were intimately attached to the contracture; their retinacular role has been discussed earlier
limited exposure of the neurovascular bundles restricted to the basis of the digits, leaving the delicate system of connective tissues as far as possible in place; the preservation of the fat and areolar tissue around the neurovascular bundles minimises the disturbance to the anatomical and physiological mechanisms of the hand and makes it less likely that they will be intimately bound down by scar tissue in any recurrence
maximum conservation of the adjacent bordering longitudinal fibres as the healing process in severed longitudinal fibres may cause reappearance of the disease at that site.

10.2.4 Skin closure

Since there is no wide dissection, the likelihood of an haematoma forming in a dead space is minimised and the skin can be sutured without drainage. In fact, up to now, a drain has never been used in a segmental aponeurectomy. Should skin lengthening be necessary, this can be achieved by a V-Y advancement using the pronounced curvature of the incision. A light pressure dressing is applied to the entire hand before the release of the tourniquet.

10.2.5 After-care

Next day, active mobilisation is started and a custom made dynamic extension splint is applied which should be worn continuously between re-education sessions for the first two or three weeks. This is very important, since in my experience the few patients who failed to wear the splint had bad results.