Fig. 1
Fresh cadaver, frozen wrist: lateral section showing the constraints applied on the scapholunate complex. We can notice the thickness of the palmar capsulo-ligamentous structures creating a sort of cushion positioned against the anterior translation of the carpus. C capitate, L semilunate, S scaphoid, R radius
2.1 Means to Stabilize the Distal Pole of the Scaphoid
Devices meant to stabilize the distal pole of the scaphoid play a quite important part considering the constraints transmitted by the first ray due to its anteposition. The flexor carpi radialis system (FCR) has both an active and a passive part: its osteofibrous canal is a real anterior abutment which is superimposed to the distal ligamentous complex of the scaphoid (scapho-trapezio-trapezoidal and scapho-capitate ligaments) (Fig. 2).
Fig. 2
Fresh cadaver, frozen wrist: lateral section showing the distal ligamentous complex of the scaphoid. The tendon of the flexor carpi radialis (FCR) can have accessory insertions on the scaphoid (S), on the trapezium (Tp) or on the scapho-trapezoid along its course towards the base of the 2nd metacarpal (IIM); through the trapezio-trapezoid complex, it exerts constraints in flexion on the scaphoid (red arrows). The black arrow represents the active stabilizing function of the FCR. In fact, this musculotendinous entity is opposed to an excessive volar dislocation of the tubercle of the scaphoid. The radio-scapho-capitate ligament can be clearly seen (in red, empty arrow) in its function of tense pivot between the radius and the capitate, around which the scaphoid makes movements of flexion and extension. R radius
2.2 Interosseous Scapholunate Ligament
The scaphoid is linked to the semilunate by an interosseous ligament which acts like a twisting bar as it creates a system with viscoelastic dampers. It is a nonhomogeneous system composed of three parts: the anterior part is fitted into the long and short radio-lunate ligament and the radioscapholunate ligament. The intermediate proximal part is a real avascularized fibrocartilaginous membrane that corresponds to the depressed zone during arthroscopic palpation. The posterior part is strong and securely linked to the dorsal capsule as it is adjacent to the dorsal scapho-triquetral ligament and the dorsal intracarpal ligament (Fig. 3).
Fig. 3
Fresh cadaver, anatomic preparation of the radiocarpal: the carpus has been placed in exaggerated flexion to show the volar radiocarpal ligaments and the articular section only – intermediate section – of the scapholunate interosseous ligament (black arrows). The radioscapholunate ligament (RSLL) covers the anterior part of the interosseous ligament. S scaphoid, L semilunate, TFC triangular fibrocartilage
The carpus has also a capsulo-ligamentous system (extrinsic, intracapsular and extra-synovial ligament) organized in different ways at the volar and dorsal level, which enables the adaptability to the physiological constraints of the proximal row, especially that of the scapholunate complex (Fig. 4).
Fig. 4
Fresh cadaver, frozen wrist: coronal section at the level of the midcarpal, after the removal of the proximal pole of the scaphoid (S) and the semilunate (L). (R) radius, (Tr) Trapezium. We can notice: The correct osseous covering that the styloid section of the radial socket gives the proximal pole of the scaphoid. The structural differences between the volar and dorsal capsulo-ligamentous complex. We can underline the orientation of the volar radiocarpal ligaments (RSCL radio-scapho-capitate ligament, LRLL long radio-lunate ligament, SRLL short radio-lunate ligament) which have a reversed V-shape with converging arms on the capitate and lunate, making a less elastic and more stable system with ‘a central symmetry’ and with shorter and stronger ligaments: RSLL the radio-scapholunate ligament or the ligament of Testut and Kuentz. On the contrary, the dorsal capsule, which is thinner, seems to be reinforced by the dorsal intercarpal ligament which is tensed between the pyramidal and the STT complex (scapho-trapezio-trapedoidal) and linked to the posterior and more dorsal parts of the scapholunate and luno-triquetral interosseous ligaments (tips of the red arrows), where the posterior scapho-triquetral ligament originates. The dorsal intercarpal ligament and the dorsal radio-triquetral ligament (or dorsal radiocarpal, which belongs to the carpal ulnar sling of Kuhlmann – empty white arrow) form an oblique ligamentous ‘V’ with the apex centred on the pyramidal: a ligamentous system with an ‘eccentric symmetry’, longer and thinner but much more elastic oblique ligaments. The carpal tendinous cage created by the extra-articular slings (retinaculum of the flexors and retinaculum of the extensors; the latter is made more visible once the tendons are removed), insures a dynamic control system which elements are set in rays, forms a system with ‘radial symmetry’ which allows and adjusts wrist motion in all directions: FCR flexor carpi radialis, ECRB extensor carpi radialis brevis, ECRL extensor carpi radialis longus
2.3 Assessment of the Anatomic Aspects
From a strictly anatomic point of view, the scapholunate joint is characterized by the superimposition of two smooth articular facets, creating an arthrodia in the presence of a syndesmotic element at the level of the proximal pole between two bones. The clinical experiment shows smooth joints, and especially syndesmoses show particular sensitivity to the passage of a metallic synthesis tool as it develops an important secondary fibrosis. Thus, if we want to make an ‘arthrofibrosis’ as close to the physiological condition as possible, it seems logical to treat an instability resulting from the injury of a syndesmosis by stabilization using trans-articular synthetic means.
Although we noticed an anatomic division of the interosseous scapholunate ligament into three parts, it would be an error to give a major role to particularly ligamentous parts. The mere notion of ‘interosseous ligament’ should be restricted to the intermediate section, that is to say, the sole fibrocartilaginous, avascularized and thus unrepairable section. On the contrary, the anterior and posterior parts of the scapholunate ligament are perfectly integrated into the volar and dorsal extra-synovial ligamentous system and consequently reminiscent of the system of all extra-articular ligaments with many cells and well-developed vascularization.
The proximal row is a complex system that has to present both a twisting elasticity enabling the flexion-extension of the scaphoid and stability enough to resist without bending too much the constraints of compression transmitted by the distal row and more particularly by the capitate. The far more elastic system of the volar carpal ligaments and the dorsal intercarpal ligaments enables the distal parts of the scaphoid, the semilunate and the pyramidal to execute limited movements on the sagittal plane and allows controlled twisting of the scaphoid-semilunate pyramidal chain. The correction of a rotary instability of the scaphoid at a chronicle level has to take into account the execution of a scapholunate ‘arthrofibrosis’ and the stabilization of the scaphoid distal pole. Surgical techniques aimed at reconstructing the capsulo-ligamentous system and preserving the anatomic characteristics of the physiological stabilization means must be given priority. The reconstruction of a dorsal capsulo-ligamentous system, especially that of the dorsal intercarpal complex, seems to guarantee limited stiffness and can be associated, if necessary, to scapho-trapezial stabilization at the volar level.
3 Garcia-Elias Classification
In January 2006, in an article published in the Journal of Hand Surgery, and which has become an important reference as far as injuries of the scapholunate ligament are concerned, Marc Garcia-Elias proposed a new scoring system based on answers to five questions dealing with the status of the wrist in chronic injuries [3]:
1.
Is the scapholunate ligament, and more particularly its dorsal section, intact?
2.
Is the injury of the scapholunate ligament partial or not?
3.
Is the scapholunate ligament repairable?
4.
Are osseous connections normal?
5.
Is the scaphoid reducible?
6.
Are cartilages normal?
This questionnaire results in a six-stage classification distributed as follows:
Stage 1: There is a mere partial injury which is likely to be repaired thanks to a normal line, a reducible scaphoid and healthy cartilages.
Stage 2: The injury is complete but intact repair seems possible.
Stage 3: There is an important injury of the scapholunate ligament but the osseous connections are still normal.
Stage 4: There is a complete tear of the scapholunate ligament with a dislocation of the scaphoid, but reduction appears possible.
Stage 5: Reduction is not spontaneous as the horizontalization of the scaphoid is settled.
Stage 6: Cartilages are affected (SLAC 1–4).
On this basis, Marc Garcia-Elias proposed the following therapeutic chart:
Stage 1: It should be considered scapholunate broaching under arthroscopic control for acute cases and scapholunate broaching associated with dorsal capsulodesis for chronic cases.
Stage 2: Suture of the scapholunate ligament by open surgery.
Stage 3: Reconstruction either by bone-ligament-bone fixing or reconstruction by the three-ligament technique.
Stage 4: Reconstruction by ligamentoplasty.
Stage 5: Scapho-trapezio-trapezoidal arthrodesis is the most logical indication but in some cases after cleaning periosseous fibrosis and eventual reduction, stage 5 could be turn into stage 4 with reconstruction by ligamentoplasty.Related posts:
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