16. Conclusions
The purpose of this study was to determine the place of segmental aponeurectomy in the treatment of Dupuytren's disease in the light of today's knowledge of the patho-physiology of the disease and through the comparison of the achieved short - and long term results with those published for other procedures. We also wanted to propose a rationale for the choice of the most adequate treatment.
At this stage, what conclusions can be drawn?
16.1 Review of the literature
16.1.1 Pathological anatomy
Dupuytren's disease follows anatomical pathways and all of the finger contractures that occur can be explained on the basis of a pathological thickening and shortening of normal fascial structures. The diseased tissue thus appears in a predictable rather than a haphazard fashion and no cord appears outside the normal pre-existing anatomical structures.
All parts of the palmar and digital aponeurosis are not affected in the same way by the disease. For example, the aponeurosis of the thenar muscles is never diseased whereas the aponeurosis of the hypothenar muscles is often involved.
All affected parts of the aponeurosis derive from the same embryological layer, the most superficial. This is the layer that has attachments in the deep dermis and the question of Dupuytren's disease origin is thus raised. Has it an embryological origin? Is it a pathology of the deep dermis or is it a response to mechanical stimuli?
The answer to all three questions could be positive. The exclusive involvement of the most superficial embryological layer of the aponeurosis points to a tissue specific disease and pleads against a response to pure mechanical stimuli that would affect other tissue layers as well. Differences in mechanical stimuli cannot, for example, explain that Grayson's ligaments are almost always involved in digital Dupuytren's disease whereas Cleland's are never. However shearing forces are certainly more intense in the layer of the aponeurosis that has attachments in the deep dermis and Dupuytren's disease is particularly frequent on the ulnar border of the little finger where forces are acting in several directions due to the intricate anatomical disposition. Mechanical stimuli seem thus to be part of the problem. On the other hand, the absence of recurrences after excision and grafting of the involved skin as achieved by dermofasciectomy clearly indicates that the disease could be related to the deep dermis or perhaps to the attachments to the most superficial fibres of the aponeurosis and that brings us back to the starting question.
16.1.2 Connective tissue biology
The study of the normal connective tissue shows an intricate relationship between cells, extracellular fibres and ground substance. Its tridimensional architecture and its biochemical composition reflect the kind of mechanical stresses it is submitted to.
Connective tissues react in predictable ways to the constraints of their environment. The study of the total quantity and the proportions of the various types of collagen and of the various proteoglycans and the tridimensional relationships of these elements in Dupuytren's disease gives some insight into the mechanisms involved in the development of the contracture.
Indeed, the examination of histological, biochemical and metabolic features of Dupuytren's disease indicate that many of these are non-specific biological responses common to a variety of mesenchymal connective tissue situations.
16.1.3 Histopathology
Dupuytren's disease evolution can be subdivided into three stages: proliferative, involutional and residual. The nodule, focus of proliferating fibroblasts, is the initial lesion in the proliferative stage. Its cellularity is indicative of the activity of the disease. In contrast to the high cellularity of the nodules, the fascial bands, made up of densely packed collagen fibres, are relatively acellular.
Myofibroblasts, cells combining characteristics of fibroblasts and of smooth muscle cells, are present in the nodules. They are most probably responsible for the retraction of the aponeurosis.
The same subset of myofibroblasts, probably derived from smooth muscle cells, is found in hypertrophic scars and in other fibromatoses but not in normal granulation tissue.
A clinically important finding is that palmar fascial tissue deliberately taken at the farthest distance from clearly involved Dupuytren's tissue, and representing specimens indistinguishable clinically from normal palmar fascial tissue, in all cases showed all the biochemical changes seen in Dupuytren's collagen even though at the ultrastructural level no pathology was apparent. Biochemical changes thus occur before the fibroblasts are morphologically modified or replaced by myofibroblasts.
These observations are clinically important and have practical consequences:
- it is unthinkable to surgically remove all the fascia involved by Dupuytren's disease;
- the treatment should be aimed at the nodules where the retraction occur;
- the fibrous chord, which is reactional, only fixes the retraction and plays no role in the evolution of the disease.
16.1.4 Dupuytren diathesis
Many studies have noted Dupuytren's disease in several members of a family, but the exact nature of the relationship remains unclear.
The idea of a Dupuytren diathesis, the term expressing a predisposition, is hard to define and has done little to clarify the situation. An index of the severity of the disease partially based on such proven unreliable factors as the existence of a positive family history or an early onset of the disease, cannot be very useful to establish the most appropriate treatment and we clearly need more objective data.
16.2 Personal data
16.2.1 Epidemiology of surgical patients
There is no significant difference between our observations and those of Mikkelsen and McFarlane who have published exhaustive studies. This observed similarity has several consequences:
- as far as our recruitment is typical for Belgium, one can say that the Belgian surgeon is faced with the same type of Dupuytren's disease as his colleagues working with patients of Northern European origin (it would be odd to have an atypical recruitment for Belgium and still observe the same population parameters as in other Northern European countries);
- being certain that the manifestation of the disease is the same as in other countries, we can safely compare our surgical results with those published by others working on the same population.
A number of conclusions can be drawn in relation to the Dupuytren diathesis theory:
- men have a greater extension deficit, more involved rays, more involvement of the radial rays and an earlier onset of the disease; even if sex is not related to other patient variables, it clearly plays a role in the aggressiveness of the disease;
- family history, an unreliable parameter, is related to no other variable except the age of onset and the presence of ectopic sites of the disease; from this data, family history cannot be used as an index of the severity of the disease;
- the presence of ectopic sites of the disease is positively related to a greater extension deficit, more involved rays, more involvement of the radial rays and of both hands; it is certainly a good index of the severity of the disease;
- the involvement of both hands, observed in three quarters of the patients, is related to a greater extension deficit and more involved rays but not to radial rays; it is probably not a good indicator of the severity of the disease as it is seen often and the observed frequency would probably even rise on later follow-up;
- patients reporting a local trauma have signs of a less aggressive disease as they have a later onset of the disease, less involvement of both hands, less extension deficit and less rays involved;
- diabetes is, in the literature, associated with a milder form of Dupuytren's disease and epilepsy with a more aggressive one; present results do not confirm this view;
- alcoholism, certainly under-estimated in this series, is associated with more involvement of both hands, more extension deficit and more involved rays; it is probably related with a more severe course of the disease;
- the involvement of the radial rays, seen more often in men and in the presence of ectopic sites, is perhaps an indicator of a more severe disease.
Two factors are thus clearly related to the severity of Dupuytren's disease, namely sex and the presence of ectopic sites. Three are possibly related, the involvement of radial rays, alcoholism and a history of local trauma. The early onset of the disease, bilaterality and a positive family history that Hueston recognises as signs of a strong diathesis do not seem to be of any use for the measure of the severity of the disease.
16.2.2 Segmental aponeurectomy: early results
Segmental aponeurectomy finds its rationale in the modification of the mechanical stresses applied on the retracted aponeurosis.
The comparison of the results achieved with segmental aponeurectomies with those published for other procedures supports our reliance on this less extensive and less aggressive surgical technique. Indeed, the correction of the contracture is equal and often better than that obtained with classical operations and the overall complication rate is much lower.
The analysis of the variables contributing to the outcome of the operation points to some important factors:
- localisation of the disease: MP joint retractions have a far better prognosis than contractures of the PIP joints, PIP joints of the index and little fingers have the worst prognosis;
- previous operation: it is a contra-indication of segmental aponeurectomy;
- ectopic sites: the correction of the contracture is less satisfactory in patients who have ectopic localisations of the disease;
- number of involved rays: it plays an adverse role in the quality of the correction.
This analysis also determines the best timing for the operation: joint contractures of less than 30° are best not operated upon.
16.2.3 Segmental aponeurectomy: late results
From the analysis of the late results after segmental aponeurectomy, several conclusions can be drawn:
- the operation brought a lasting correction of the contracture in the hands that did not develop a recurrence or an extension of the disease; the follow-up values are even slightly better than the immediate postoperative measurements except for the proximal interphalangeal joint of the little finger;
- the proportions of recurrences, extensions and hands free of the disease are similar to those published after other classical procedures;
- most studies are invalidated by the fact that the follow-up periods are unequal;
- the introduction, by life table analysis, of corrective factors allowing for the different follow-up periods gives, by projection, a proportion of 68 % of recurrences after ten years; this percentage is very close to that published by Tubiana, for classical procedures, in a very long term review;
- this very high percentage of recurrences to which a number of extensions should be added confirms that surgery is not curative in Dupuytren's disease; after ten years, almost no hand would be left clear of the disease;
- as far as comparisons are possible, the type of operative approach does not make a clear difference to the progression of Dupuytren's disease;
- patients operated before the age of 45 or having ectopic sites of the disease run a higher risk of recurrence;
- all the other factors, local or general, do not play a prognostic role.
16.2.4 Segmental aponeurectomy: summary
Segmental aponeurectomy allows an equal or even better correction of the contracture than that achieved with classical operations but with a much lower complication rate. The benefit is thus evident because complications often lead to unacceptable losses of function.
The achieved correction is lasting and the proportions of recurrences, extensions and hands free of disease are similar to those after classical fasciectomies.
Beyond the clinical advantages of a less aggressive procedure, these results imply that Dupuytren's disease does indeed respond to mechanical stimuli since the pathological tissues that remain in place disappear (at least temporarily and definitively in about one third of the cases) after the interruption of the retracted aponeurosis. This pleads in favour of a functional origin of Dupuytren's disease that would arise as the exaggerated consequence of adaptive responses to applied mechanical stimuli.
16.2.5 Dermofasciectomy
Dermofasciectomy allows a very good if not perfect control of recurrences but there is a price to pay in the form of many more complications.
16.2.6 Proposed sequence of treatment
The previous observations reinforce our opinion about the choice of the adequate procedure in the treatment of Dupuytren's disease:
- the first operation, which is for most patients the last one, must be as simple as possible to keep the complication rate very low;
- segmental aponeurectomy is thus proposed for all primary cases and for extensions of the disease where this operation is technically feasible;
- on the other hand, dermofasciectomy is indicated for all cases reoperated for a recurrence; the advantages of this compromise are:
- in the event of an aggressive recurrence that imposes a surgical treatment, the second operation is, almost certainly, the last one;
- the second operation, though more difficult, is nevertheless performed in good conditions because there is not too much scar tissue;
- a third operation in technically very difficult conditions is avoided.