Keywords
scapholunate lesion - dynamic stabilization - mobilization - recovery
Introduction
Scapholunate instability is the most common carpal ligament injury. However, it is
a condition with complex etiology, diagnosis, and treatment, which is becoming better
understood due to advances in biomechanical studies.[1] For this reason, the surgical treatment of this condition has grown in recent years.[2]
[3]
Following an acute injury to the scapholunate ligaments, their intrinsic stabilization
improves wrist function, reduces symptoms (pain, clicking, loss of strength, limited
mobility), and delays secondary radiocarpal arthropathy. In line with studies carried
out by Corella et al.[4] and Carratalá et al.,[5] minimally-invasive arthroscopic surgery for lesion repair has reduced the rate of
complications related to open surgery.
Advances in biomechanical studies highlighted the role of secondary stabilizers of
the scapholunate pair. The scaphoid-trapezium-trapezoid (STT) complex is one of the
fundamental elements for scaphoid stability and extension.[1] Failure of these components results in the well-known flexion and pronation movement
of the scaphoid, triggering the dorsal tilt in dorsal intercalated segment instability
(DISI) of the lunate and diastasis of the scapholunate pair.[6] Subsequently, the loss of carpal height and progressive collapse cause pain, loss
of mobility, and loss of strength. The sustained instability makes the scapholunate
dissociation irreducible, and the surgical solution is less satisfactory.[7]
Classically, after the surgical treatment of a scapholunate injury by shrinkage, reclamping,
or ligamentoplasty, immobilization is mandatory to avoid scapholunate mobilization
and protect the surgical technique employed. Even though Corrella et al.[4] have published a study describing reduced immobilization times in scapholunate ligamentoplasty,
most patients are under postoperative immobilization for no less than four or six
weeks.[3]
This immobilization period usually results in a joint stiffness that may not be correctable
despite rehabilitation, and can overshadow therapeutic outcomes. In addition, patients
often demand a faster return to work and sports practice.
For correct scapholunate stabilization and immediate mobilization, we herein describe
a surgical technique for selective dynamic immobilization of the STT joint that reduces
the flexion movement of the scaphoid, increasing the chances of proper healing of
the primary stabilizers, at the same time that the secondary stabilizers begin to
move.
Indications
The indications for this procedure include:
-
– Acute repair of a scapholunate ligament injury associated with reclamping or shrinkage
in chronic, stages I-II Geissler tear;
-
– Scapholunate ligament injury with scaphoid fractures; and
-
– Scapholunate ligament injury with a fracture of the distal end of the radius.
Contraindications
-
- Osteoporosis;
-
- Chondropathy in the STT joint;
-
- Injury with growth potential detected during childhood or adolescence; and
-
- Previous neurovascular or tendon pathology in the wrist.
Surgical anatomy
The scapholunate ligament is considered the most important intrinsic carpal ligament.
It stabilizes the articular pair of the scaphoid (proximal pole) and the lunate in
continuity, with a “C”-shaped morphology[8] ([Figure 1]).
Fig. 1 Arthroscopic anatomy of the scapholunate ligament. Radial (A) and midcarpal (B) visualization.
It consists of three segments: dorsal, proximal, and volar. The dorsal portion is
the thickest ligament bundle (with approximately 3 mm in thickness and 5 mm long),
and it accounts for most of the stability. The volar portion is thinner (1 mm) and
connected to the palmar radioscaphocapitate extrinsic ligament. Finally, the proximal
portion consists of fibrocartilage, with highly-variable thickness.
The scapholunate ligament is considered the primary stabilizer of the scapholunate
joint. However, other associated extrinsic ligaments act as secondary stabilizers.
The dorsal area contains the radiocarpal (radiotriquetral) and the intercarpal (scaphotriquetral)
ligaments, whereas the volar area contains the radioscaphocapitate, long radiolunate,
and radioscapholunate ligaments.
Moreover, the intrinsic ligaments of the scaphotrapezoid joint can significantly influence
the dorsal stabilization of the scaphoid in case of a scapholunate injury.[9] The dorsal part consists of the trapeziotrapezoid ligament, whereas the palmar part
consists of the trapeziotrapezoid, scaphotrapezoidal, capitotrapezial and scaphotrapezial
interosseous ligaments; the latter, deemed the most important, is divided into radial
and ulnar bundles. In addition, it is accompanied by two ligaments that help joint
stability: the trapeziocapitate and the palmar scaphocapitate ligaments.
Although the physical examination and magnetic resonance imaging (MRI) help to establish
the diagnosis of scapholunate instability, the definitive diagnosis relies on arthroscopic
visualization. The Geissler classification establishes the degrees of dissociation
and the surgical protocol for each case.[10]
Repair is indicated in ligaments with stage-II, -III, or -IV injuries. Regardless
of the surgical procedure performed, most authors advise fixation of the carpal bones
using Kirschner wires, either transscapholunate or transscaphocapitate. The aim is
to avoid the dreaded anatomical movement of a dissociated scaphoid, that is, flexion
and pronation, with dorsal lunate tilting (DISI) and carpal collapse.
A less aggressive immobilization method, performed after an arthroscopic scapholunate
ligamentoplasty, uses splints and orthoses; later, these devices are progressively
removed.
Surgical technique
The scaphoid-metacarpal stabilization (SMS) surgical technique is based on a high-resistance
suture wire with double cortical button anchoring (Mini TightRope, Arthrex, Naples,
FL, US, or MicroLink, Conmed, Largo, FL, US); one button is at the radiopalmar margin
of the scaphoid tubercle, and the other is at the ulnar cortex of the base of the
third metacarpal bone.
With maximum tension, this wire is placed after the repair of the scapholunate ligament.
This dynamic stabilization maintains the height and length of the scaphoid by this
vectorized distal and ulnar grip on the third metacarpal bone.
These devices are subject to extra-articular bone points, so they do not produce chondral
symptoms; in addition, mobilization is allowed one week after the intervention.
This technique requires an endobutton-type implant:
-
– Mini TightRope: device formed by a suture cable with high tensile strength. It has two metallic cortical
support elements on both sides of the cable.
-
– MicroLink: device similar to the previous one, but the cortical support elements are not metallic;
in addition, it is an all-suture system.
The steps of the surgical technique are as follows:
-
Scapholunate repair after arthroscopic assessment of the injury (thermocoagulation,
reclamping, or capsulodesis) ([Figure 2]).
-
The most distal and radial region of the scaphoid tubercle is the point of origin
of the tenodesis. Ensure needle insertion under scope control. This needle has a wire
at its base to capture the cable ([Figure 3]).
-
The needle is directed distally and ulnarly, through the ulnar cortex of the base
of the third metacarpal bone, immediately distal to its junction with the fourth metacarpal
bone.
-
The suture cable passes through the needle, and the cortical support devices are placed,
avoiding damages to the common extensor tendons, and ensuring complete cortical part
support ([Figure 4]).
-
The correct position of the implants is checked using a scope, and the effect achieved
is verified through the arthroscopic midcarpal portal.
Fig. 2 Arthroscopic image of a Geissler stage-IV scapholunate tear.
Fig. 3 Dissection of the radial edge of the scaphoid (A) and scapho-metacarpal tunneling (B) to pass the anchor. Radiological follow-up image (C).
Fig. 4 Insertion of the ortical button anchor (A). Dissection of the intermetacarpal space and compression of the metacarpal by the
button (B).
Postoperative period
The patient must wear a wrist bandage after surgery.
The patient is discharged on an outpatient basis, and the first follow-up visit occurs
during the first postoperative week. The surgical wound undergoes proper treatment.
At home, the patient must follow an active kinesiotherapy protocol for radiocarpal-midcarpal
and radioulnar mobility and use a rigid forearm orthosis for daytime and nightly protection.
Before two weeks, the patient is referred to the rehabilitation service for physical
therapy.
Hand activity is severely restricted until the third postoperative month, when the
scapholunate ligament healing is assessed through an MRI scan.
Next, high-demand activity is allowed.
At this time or later, the cable is excised with or without button removal under local
anesthesia if the patient presents limited flexion-extension or deviations due to
the high tension of the tenodesis.
Complications
-
- Irritative synovitis at the extensor digitorum communis due to friction against
the metal implant supported by the third metacarpal bone.
-
- Tension-related wrist symptoms with no observable mobility deficit in a patient
requiring implant removal.
Clinical case
A 48-year-old male patient presented a right-wrist trauma after an accidental fall
resulting in a diagnosis of scapholunate tear.
Surgical treatment was indicated and performed under axillary plexus anesthesia. The
arthroscopic repair used two anchors in a Geissler grade-IV scapholunate tear. Dynamic
tenodesis from the scaphoid to the third metacarpal bone was performed under radiological
control according to the technique described ([Figure 5]).
Fig. 5 Patient diagnosed with scapholunate tear (A). Double arthroscopic anchorage and scaphometacarpal tenodesis (B).
Subsequently, carpal stability was checked through arthroscopy.
The patient received a compression bandage and was discharged after an outpatient
procedure.
Protected mobilization with removable orthosis began at 7 days, and rehabilitation
started at 4 weeks, when the patient had no pain and presented a full range of joint
motion in flexion, extension, pronation, and supination, with 30 kg of force (10 points
lower in comparison with the contralateral side) ([Figure 6]). The score on the Disabilities of Arm, Shoulder, and Hand (DASH) questionnaire
was 10. There were no symptoms of peri-implantation, and the clinical maneuvers for
scapholunate instability yielded negative results.
Fig. 6 Mobility at the first postoperative month.
A plain radiological study showed stability with no signs of dissociation. An MRI
of the wrist three months after the injury confirmed advanced healing of the scapholunate
ligament ([Figure 7]).
Fig. 7 Control MRI scan at 3 months.
The patient requested discharge to return to work after two months, and implant removal
has not been proposed due to complete mobility and lack of associated symptoms. A
control MRI showed scapholunate healing.
