**10. Arthroscopic treatment of the scapholunate ligament tears**

Scapholunate interosseus ligament (SLIL) should be considered as a key stone of the intercarpal stability. It is U shaped in the sagittal plane and has three components – dorsal, volar and proximal [48]. The dorsal segment is the strongest portion with a tensile strength of 260 - 300 N and approximate thickness of 3 mm [32]. The proximal component is the weakest and avascular, The volar part has a tensile strength of 120- 150 N and approximate thickness of 1 mm. The palmar and dorsal segments work collectively to prevent rotational translation between scaphoid and lunate, whereas the intermediate segment has little role in stability [49–51].

Scapholunate stability is effectively ensured by a complex associating the dorsal and volar portions of the SLIL, the dorsal intercarpal (DIC) ligament, the dorsal radiocarpal (DRC) ligament, the radioscaphocapitate (RSC) ligament, the scaphotrapezial (ST) ligament, and the dorsal capsulo-scapholunate septum (DCSS). The integrity of these various stabilizers is taken into account while determining the arthroscopic classification of "predynamic" scapholunate instability [52].

When the SLIL is injured, the scaphoid tends to move into volarflexion, while the lunate, which is still fixed to the triquetrum, is forced, due to carpal kinematics, to follow the triquetrum into dorsal extension. The opposite happens with time when the LT interosseous ligament (LTIL) is injured. This static instability is often referred to radiologically as dorsal intercalated segment instability (DISI), following an SLIL injury and volar intercalated segment instability (VISI) following a LTIL injury [53].

The first arthroscopic classification of SLIL tears was presented in 1996 by Geissler et al. [54] using a 4-stage grading system (**Table 4**) (**Figures 23** and **24**).

In 2013 Messina et al. published the European Wrist Arthroscopy Society (EWAS) Classification of Scapholunate tears which was based on anatomical arthroscopic study and is an evolution of Geissler's classification (**Table 5**) [55].


#### **Table 4.**

*Geissler's arthroscopic classification of SLIL tears.*

**Figure 23.** *Geissler grade II tear – attenuation an hemorrhage (\*) of SLIL.*

The existing classifications, however, describe the dynamic instability of the scapholunate joint but do not distinguish the site of ligament attenuation or tear, particularly in its volar portion.

The choice of the procedure for SLIL injuries in the absence of arthritis depends on the extent of the lesion, quality of the ligament remnants and reducibility of the joint [53].

#### **Figure 24.**

*Geissler grade IV tear – arrow shows gap between scaphoid and lunate. Scope easily passes between bones and slides into midcarpal joint.*


*SLIL: scapholunate interosseous ligament. MC: midcarpal. RC: radiocarpal. RSC: radio-scapho-capitate. LRL: long radiolunate. DIC: dorsal intercarpal ligament. SL: scapholunate. TH: triquetro-hamate. ST: scaphotrapezial. DRC: dorso radiocarpal. DISI: dorsal intercalated segmental instability.*

#### **Table 5.**

*Arthroscopic EWAS (European Wrist Arthroscopy Society) Classification and corresponding anatomopathological (AP) findings in cadaver specimens.*


#### **Table 6.**

*Six questions by Marc Garsia-Elias.*

Garcia-Elias et al. [56] developed a set of 6 questions that provide a useful framework for developing stage-based treatment algorithms. By answering these questions in terms of yes or no, each case can be placed into one of seven categories (**Table 6**). As expected, the increasing number of negative answers indicates a progression of the dysfunction from minimal (Stage 1) to maximal (Stage 7). In general, all instabilities from the same stage will be treated similarly.

Detailed description of indications and treatment methods depending on the time after injury, the stage of SLIL disruption and stability or instability of the carpus is presented in the report of the IFSSH Committee On Carpal Instability in 2016 (part 2: Management of scapho-lunate dissociation [57].

Since this book is oriented to the arthroscopic methods of treatment further discussion on open surgical procedures will not be proceeded.

In acute injuries, arthroscopy can be used to determine the extent of scapholunate interosseous ligament injury. Partial tears may be treated by percutaneous pinning of the scaphoid and lunate, thus allowing for the possibility of primary healing or fibrosis.

Predynamic or occult SL injury results from an incomplete tear of the SL ligament. In selected cases with reducible scapholunate instability (Garcia-Elias stages 2, 3 and 4) where the ligament is partially (**Figure 25**) or completely ruptured, and where the scaphoid is well aligned or can be reduced, Mathoulin et al. proposed the arthroscopic dorsal capsuloplasty, which may be combined with K-wire fixation of the scapholunate and the scaphocapitate joints [58, 59].

This technique can be performed only in cases when ligament stumps remain attached to the scaphoid and lunate. This technique includes synovectomy of midcarpal and radiocarpal joints. Then the scope is introduced into the 6R portal to inspect the gap between the lunate and the dorsal capsule (**Figure 26**).

An absorbable monofilament suture is passed through a needle. This needle is inserted through the skin via the 3–4 portal, then shifted slightly distally so as to cross the joint capsule (**Figure 27**).

The needle is located inside the joint through the scope and then pushed through the SLIL stump on the scaphoid side. The needle is oriented dorsal to volar and angled proximal to distal, allowing it to enter the midcarpal joint (**Figure 28**). A second needle and suture are then inserted parallel to the first into the SLIL stump attached to the lunate. The scope is returned to the MCU portal. The two needles are located inside the midcarpal joint, after they have passed between the scaphoid and lunate. Both sutures are externalized via MCR portal with hemostat and the knot is tied outside the joint. Then the knot is pulled back into the midcarpal joint (**Figure 29**).

*Partial, reparable rupture of SLIL, a- view from MCU portal, yellow arrow shows the step off between articular surfaces od scaphoid and lunate, red arrow points detachment of SLIL from lunate, b- The same patient – normal SLIL in RC joint, view from 3 to 4 portal.*

**Figure 26.** *View from 6R portal with detached dorsal capsule and injured dorsal capsuloligamentous scapholunate septum (DCSS).*

At this point the traction of the wrist is released to reduce the gap between scaphoid and lunate. Transfixation of the scapholunate and scaphocapitate joints with K-wires can be performed if reduction is insufficient. The final knot is tied after the wrist is released from traction and positioned in slight extension [52].

**Figure 27.** *Needle inserted via 3-4 portal and shifted distally to enter the midcarpal joint.*

**Figure 29.** *The inner knot of both sutures at the level of SL joint.*

After treatment includes 8 weeks of immobilization and an adequate rehabilitation.

There are several other, more complicated arthroscopic SLIL repair procedures described, but the indications of these techniques are limited to predynamic and dynamic SL instability.

P.C.Ho et al. in 2002 designed an arthroscopic assisted box reconstruction of scapholunate ligament with palmaris longus (PL) tendon graft [60]. It enables simultaneous reconstruction of the dorsal and palmar SL ligaments anatomically with the use tendon graft in a boxlike structure. With the assistance of arthroscopy and intraoperative imaging as a guide, a combined limited dorsal and volar incision exposed the dorsal and palmar SL interval without violating the wrist joint capsule. Bone tunnels of 2.4 mm are made on the proximal scaphoid and lunate. A palmaris longus tendon graft is delivered through the wrist capsule and the bone tunnels (**Figure 30**) to reduce and connect the two bones in a boxlike fashion.

Once the joint diastasis is reduced and any DISI malrotation corrected, the tendon graft is knotted and sutured on the dorsal surface of the SL joint extracapsularly in a shoe-lacing manner (**Figure 31a,** and **b**). Additional suture anchors can be placed at the dorsal bone tunnels for the scaphoid and lunate for additional graft fixation. The RL pin is removed at the beginning of the third week. The cast is then changed to a thumb spica splint for an additional 2 weeks, at which time gentle wrist mobilization is allowed out of the splint. The SC pins are removed after 8 weeks. The potential risk of ischemic necrosis of the carpal bone is minimized by preservation of the scaphoid blood supply [52, 60].

**Figure 30.** *A palmaris longus tendon graft deliverd through the lunate and both capsules.*

Corella et al. in 2011 published a novel all arthroscopic technique for scapholunate instability [61]. They developed the BTT ligamentoplasty - Bone (base of second metacarpal bone), Tendon (flexor carpi radialis graft), Tenodesis (in the scaphoid and lunate). This technique aims to reproduce the tripple tenodesis technique proposed by Garcia-Elias et al. in 2006 [56], but with an arthroscopic approach reducing soft tissue trauma. It reconstructs both the dorsal and volar portion of the SL ligament with a 3-mm graft of the FCR tendon, which is fixed to the scaphoid and lunate tunnels with interference screws. Graft resistance and strength can be increased with the use of a 1.3 mm SutureTape. The SutureTape is passed and fixed with the screws along with the tendon graft. After the graft is fixed to the scaphoid bone with the anchor, the volar portion of the SutureTape that exits from the lunate tunnel is sutured to the portion that exits from the scaphoid tunnel. It's recommended to start early postoperative wrist mobilization with this technique – dart-throwing motion from the 3rd week and flexion/extension movements from the 5th week after surgery [62].

**Figure 31.** *Tightened tendon graft, view from volar (a) and dorsla (b) side.*
