INTRODUCTION TO A BETTER UNDERSTANDING OF THE PHYSIOLOGY OF LFEXOR TENDON SLIDING in ZONES III, IV AND V
In 1979, microsurgery was used to carry out transfers of vascularized tendons in turkeys. Although the functional results were hardly
convincing due to the difficulties of post-operational management, this work did influence our concept of tendon surgery. What was impressive in the turkey
research was the importance of the mesotendons, as well as the rather close and very dense relations between this vascularization and the tendon itself. In
the field of reconstructive plastic surgery, the Chinese flap, developed at the expense of the radial artery, brought with it new possibilities. However the
residual scars observed after radial forearm flap treatment were discouraging and we began to orientate our work towards the ulnar artery, where the residual
cutaneous scar is much more lateral and more cosmetically acceptable.
During these operative dissections, a barely known artery of enormous vascular potential was encountered. The multi-tissue distribution
in the lower third of the forearm was at the origin of different types of island transfer, either bone, skin or tendon. In fact, during our research, we
noticed that the ulnar artery constantly branched off to skin, to bone and to the Common carpal sheath and the superficial flexor tendons, focussing on zones III,
IV and V.
A series of microsurgical dissections allowed the following to be noted :
- the flexor tendon does not slide in a completely unrestricted way within the sheath; its course is limited.
- it is possible to keep a flexor tendon in the sheath thanks to vascular adhesion, which itself is connected to a vascular mesotendon by a
branch of the ulnar artey.
Thus we found a perfectly vascular mesotendon structure in macroscopic histological continuity. This provided a very new anatomical vista.
Hence the idea of making vascular retrograde island transfers in the same way as the ulnar flap to solve the problem of flexor tendon
reconstruction surgery.
As these samples were taken from inferior third of the forearm and from the carpal tunnel, close study of zones III, IV and V
was possible, these being well adapted to anatomical description.
The following observation is noteworthy : when a tendon moves to make the finger bend, it also moves in the palm but without inducing the
slightest surface movement.
This phenomenon had been studied very little as it had been solved in previous decades by the concept of a theoretical entity :
THE CONCEPT OF VIRTUAL SPACE.
In this concept, the tendon slides in the carpal sheath like a bullet in a gun barrel without touching the sides, or, rather, it slides
in membranous or visceral layers like a hamburger.
This strange physical construction and odd histological layout causes utter confusion between the roles and definitions of the
paratendon, mesotendon and peritendon.