26.1 Introduction

The scapholunate (SL) complex consists of the intrinsic and extrinsic ligaments. The intrinsic portion of the scapholunate interosseous ligament (SLIL) has three segments: dorsal, volar, and proximal. The dorsal segment is biomechanically the most important. It is made up of very thick transverse fibers that resist rotation. The volar segment of the SLIL consists of long, oblique fibers that allow sagittal rotation. The proximal segment consists of nonvascularized fibrocartilage that is often perforated secondary to degeneration in the elderly. The main extrinsic ligaments of the SL complex are the radioscaphocapitate ligament, the long and short radiolunate ligaments, and the dorsal radiocarpal and dorsal intercarpal ligaments. The impact of these ligaments also being damaged on SL instability is not fully understood.

We should remember that an isolated acute SL ligament injury without instability will heal by simple immobilization in slight extension for 6 weeks.

Not correctly treated, isolated SL ligament injuries may not lead to SL dissociation on radiographs even when instability is present. On the other hand, slight weakening of the SL ligament that is not visible on X-rays can lead to pain. Typically, both the intrinsic and extrinsic systems must be damaged for complete SL diastasis to be visible on X-rays. In most cases, radiological abnormalities are not visible immediately after SL ligament injury, but appear over time because of gradual destruction of the entire ligament system. A period of “dynamic” instability, one that is visible only under certain loading conditions (e.g., tight fist), can be differentiated from “static” instability, one in which significant bone shifts are often found too late to be repaired if they cannot be reduced. This explains why this pathology is often diagnosed too late.

The concept of the interosseous ligament itself should be limited to the proximal portion, which is the only nonvascularized fibrocartilaginous portion, and therefore not repairable. Conversely, the volar and dorsal portions of the SL ligament are completely integrated into the extrasynovial volar and dorsal extrinsic ligament systems and have well-developed vascularity.

The more elastic volar and dorsal extrinsic carpal ligaments allow the distal parts of the scaphoid, lunate, and triquetral to shift slightly in the sagittal plane and control torsion of the scaphoid–lunate–triquetral chain. Reconstruction of only the dorsal capsule ligament complex seems to be sufficient to represent a solution for SL stabilization and minimizes stiffness as long as the bones are satisfactorily reduced.

The treatment approach for SL dissociation has evolved in recent years due to the development of wrist arthroscopy, which was a significant technological revolution in the 1990s just like microsurgery was in the 1970s.

Salvà-Coll, Garcia-Elias et al in 2011 ¹ showed the importance of distal scaphoid stabilization, particularly the role of the flexor carpi radialis. Meade et al, ² Short et al, ³ and Berger et al ⁴ showed that the SLIL actually consisted of three parts, with the dorsal part being the main stabilizer of the SL joint. Mataliotakis et al ⁵ and Hagert ⁶ emphasized the importance of innervation to proprioception, which allows the entire peripheral musculotendinous system to respond and protect the SL gap. They suggested that proprioception plays an important role in protecting the SL dissociation, and that it is important to protect both the anterior and posterior interosseous nerves.

Elsaidi et al ⁷ carried out a cadaver study in which they sequentially cut the various ligament components (volar, interosseous, and dorsal) and then loaded the wrist. They found that dorsal tipping of the lunate with scaphoid horizontalization, such as in cases of severe SL instability, occurs only when the dorsal attachments of the dorsal intercarpal ligament are cut.

We have observed cases of arthroscopically obvious midcarpal SL instability where the SLIL (dorsal, proximal, and volar) was intact. It was only during the systematic exploration of the dorsal capsule that we discovered isolated tears in the dorsal capsule, which was detached from the dorsal portion of the SL ligament, with easy access to the midcarpal joint from the radiocarpal joint. ⁸

In a cadaver laboratory, we used radiographs and arthroscopy to evaluate loaded and unloaded wrists after progressively sectioning the stabilizers. This work revealed worsening of the SL dissociation in all cases in which the attachment between the dorsal capsule and SL ligament was cut. ⁹

An additional cadaver study was carried out to demonstrate the presence of this anatomical structure (DCSS, the dorsal capsuloligamentous scapholunate septum), which was found in all the specimens. It consists of two transverse arches assembled into a third arch, which is larger than the other two. This capsule–ligament structure joins the dorsal portion of the SL ligament with the dorsal capsule. ¹⁰ This forms an extremely solid dorsal complex consisting of the dorsal portion of the SL ligament—a true dorsal SL ligament—the DCSS and the dorsal intercarpal, particularly the sacrotuberous ligament, and the proximal portion of the dorsal intercarpal. These three structures are closely interlinked and appear to be the key to SL stability. Therefore, arthroscopic repair aims to reconstruct the DCSS. ^{11 , 12}

26.2 Indications

This technique is recommended in all cases of SL instabilities lower than Geissler grade 4. It is very suitable for fresh cases as for older cases because aggressive shaving recreates a fresh lesion. An acute ligament injury with no dissociation may heal by immobilization.

For more unstable cases the success rate was lower, which means that other techniques may help in the future or to be a secondary option or to be then the primary choice.

26.3 Surgical Technique

A diagnostic arthroscopy is of best value in SL lesions. The scope is inserted through the 3–4 radiocarpal portal to visualize the SLIL. However, the dorsal portion of SLIL can be best seen with the scope in the 6R portal. A probe is used to assess the nature of the SL ligament injury.

In case the ligament is ruptured in the center, with two ligament stumps remaining attached to the scaphoid and lunate, the original Mathoulin SL suture technique to suture the ligament arthroscopically is performed.

An absorbable monofilament suture (3–0 or 4–0) is passed through a needle. This needle is inserted through the 3–4 portal, and then shifted slightly distally so as to cross the joint capsule. The needle is localized inside the joint through the scope and then pushed through the SLIL stump on the scaphoid side. The needle is then oriented dorsal to volar and angled proximal to distal, allowing it to enter the midcarpal joint. A second needle and suture are then inserted parallel to the first into the SLIL stump attached to the lunate (▶Fig. 26.1). The scope is returned to the midcarpal ulnar portal. The two tips of the needles are now found inside the midcarpal joint, after they have passed between the scaphoid and lunate. The two sutures can be caught through the midcarpal radial portal (▶Fig. 26.2).

The needles are removed and both sutures are pulled outside. A knot is tied between the two sutures. Traction is applied to both sutures through portal 3–4 to pull the first distal knot into the medio-carpal joint. This knot is going to be positioned between the scaphoid and the lunate (▶Fig. 26.3) just volar to the remaining dorsal portions of the SLIL. The degree of reduction in the SL gap is determined by maintaining tension on the sutures after releasing wrist traction. If reduction is satisfactory, the ligament is sutured to the dorsal capsule by the last knot, which is tied subcutaneously (▶Fig. 26.4).

If reduction is insufficient, Kirschner wires (K-wires) will need to be added to stabilize the SL joint and potentially the scaphocapitate joint. The wrist is immobilized in extension (45–60 degrees) with an anterior splint for 6 weeks in cases of suture repair only, and for 8 weeks in cases of associated K-wire fixation.

It is true that in many cases the ligament is avulsed from the lunate or from the scaphoid. Therefore, Haerle hypothesized that the effect of Mathoulin technique lays more in a capsulodesis effect rather than in suturing the SLIL, which has low healing potential anyway. For these cases, he developed the Haerle capsulodesis technique by arthroscopy.

The stability of the SL is usually assessed from midcarpal portals, by inserting a probe into the palmar, central, and dorsal portions of the SL joint. Then, the grade of instability is assessed according to Geissler or the European Wrist Arthroscopy Society (EWAS) for every portion of the interosseous ligament. ¹³

The first most important step of the technique is to shave the radiocarpal and midcarpal dorsal capsular segments adjacent to the SL space aggressively. Hereby we recreate a fresh lesion of those ligaments and capsular segments.

The skin incision to the 3–4 portal is slightly enlarged and the extensor tendons of the third–fourth compartment are gently kept aside. Thereafter, under arthroscopic control (6R portal) the first needle is inserted into the radiocarpal compartment ulnar to the 3–4 portal. This needle is slightly retracted and then passed on the dorsal horn of the scaphoid with slight radial divergence into the midcarpal compartment, transpiercing the radial septum portion (see ▶Fig. 26.5; ▶Fig. 26.6). The second needle is now inserted into the radiocarpal compartment ulnarly to the 3–4 portal, slightly retracted and passed dorsally to the lunate with slight radial divergence into the midcarpal compartment, transpiercing the ulnar portion of the dorsal septum (see ▶Fig. 26.7).

Basically, it is a very similar technique to Mathoulin until this point. The difference lies in fact that Mathoulin tries to catch the remnants of the ligament stumps by a convergent direction of the needles, while Haerle tries to catch the most possible amount of capsule that remains inserted to the scaphoid and lunate by diverging the needles.

The first needle carries a 2–0 multistranded polyethylene suture, and the second needle a looped suture thread. The polyethylene suture is pulled out through the looped suture thread and exteriorized (see ▶Fig. 26.8). Traction is released and a knot is tied on the top of the dorsal capsule on the floor of the fourth extensor sheet (see ▶Fig. 26.9). Repositioning and stability of the suture are evaluated by arthroscopy.

Postoperatively, the wrist is immobilized in a forearm cast for 8 weeks. K-wires are needed only in singular cases. No physiotherapy is applied to improve wrist flexion for up to 3 months postoperative to give the ligaments the time to heal without being stretched out.