Keywords
lunotriquetral instability - wrist arthroscopy - ligamentoplasty
Introduction
Regarding dissociative carpal instabilities, those caused by rupture of the lunotriquetral ligament have been eclipsed for different reasons, including the lack of striking acute radiological signs and the low specificity of the clinical symptoms and tests for their evaluation.
There is a current interest in the arthroscopic treatment of injuries to the intrinsic and extrinsic ligaments of the wrist, as shown by the increased number of publications and the development of minimally-invasive techniques who main goal is anatomical reconstruction.[1] As in similar ligamentoplasties,[2] these techniques require training and evaluation in cadaveric specimens before any clinical application.
The first objective of the present study was to design a lunotriquetral and radiotriquetral dorsal arthroscopic ligamentoplasty in cadaveric specimens to assess the efficacy and safety of the procedure. Our second objective was to evaluate its clinical application in a representative case. The hypothesis was that ligamentoplasty can result in lunotriquetral stability while sparing neighboring tissues and structures.
Material and Methods
Indications and contraindications
Reconstruction of the lunotriquetral ligament is indicated in patients who present the symptomatology and a clinical examination indicating a chronic, grade-III or -IV lesion (per the Geissler classification[3]), with failure of the conservative treatment, and altered carpal kinematics due to claudication of the secondary stabilizers. This procedure is contraindicated in cases of injuries with degenerative arthropathy and/or non-reducible instabilities.
Surgical Anatomy
Previous anatomical studies[4] have indicated the anatomopathological properties of the lunotriquetral ligament and its mechanism of carpal biomechanical alteration by triggering a volar intercalated segment instability (VISI). In order for this to happen, there must be an alteration in the lunotriquetral ligament and its secondary stabilizers, as well as in the dorsal radiocarpal and intercarpal ligaments. A bone-tendon-bone plasty with a free flexor carpi radialis or palmaris longus hemitendon was selected, which enables the reconstruction of the volar region of the lunotriquetral ligament, its most important portion,[5] and of the dorsal radiocarpal ligament as an extrinsic stabilizer. The technique was been performed through usual wrist arthroscopic portals and high resistance fixation systems (interference screws and harpoons) for early mobilization.
Preliminary study in specimens
A total of six cadaveric specimens were used to perform the technique and evaluate its efficacy and safety. The specimens were donated for scientific purposes and handled according to the standards of the practice. The research protocol was approved by the Ethics in Research Committee of Hospital Universitario de Bellvitge, under registration number PR 384/18 (CSI 18/62).
A forearm stabilization and wrist traction system was used (Arc Wrist Tower, Acumed, Hillsboro, OR, US) ([Figure 1]). The surgical technique described in the corresponding section was followed, except for the fact that it was performed on Geissler grade-IV lunotriquetral lesions created during the same act by complete ligament section. After reconstruction, the degree of stabilization was assessed per the Geissler classification system[3] and the ballottement test.[6] Finally, the anatomical dissection of the specimen was performed to check the integrity of the structures around the ligamentoplasty site and to specifically assess the distances to the three structures most susceptible to iatrogenic injury: the dorsal branch of the ulnar nerve (distance from the dorsal exit of the pyramidal bone tunnel), the ulnar neurovascular bundle (distance from the volar pyramidal tunnel), and the posterior interosseous nerve (distance from the lunate dorsal tunnel).
Fig. 1 Preparation and placement of the cadaveric specimen in the dissection room.
Clinical case and surgical technique
A 40-year-old male patient, with a 1-year history of trauma, ulnar pain, and subjective loss of grip strength. The physical examination showed normal joint range of motion, decreased grip strength compared to the contralateral wrist (of 23 kg, 61% of the normal value), ulnar pain, and a positive Reagan test.[7] The score on the shortened version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH)[8] was of 35, and pain was rated as 6 out of 10 per the Visual Analog Scale (VAS). Since no pathological alterations were observed in the initial plain radiographs, the patient underwent conservative treatment, consisting of immobilization with orthoses followed by physical therapy. There was no improvement after two months of therapy. A magnetic resonance imaging (MRI) scan showed no pathological findings. Due to the lack of clinical improvement, a diagnostic arthroscopy was performed, and it revealed a grade-III lunotriquetral instability. In a second intervention, before the approval for inclusion in this research protocol, a lunotriquetral ligamentoplasty was performed.
After an axillary block, preparation of the sterile field, and a proximal ischemia cuff, the limb was positioned using a wrist traction system (Arthrex, Naples, FL, US). The following classic arthroscopic dorsal radiocarpal portals were performed: 3-4, 4-5, radial midcarpal, ulnar midcarpal, and central volar portals.[9] A palpation hook was used to confirm the presence of grade-III or grade-IV lunotriquetral instability and the attenuation of the dorsal extrinsic ligaments. Using a 2.9-mm synoviotome, the redundant synovial tissue from the dorsal facets of the lunate and pyramidal bones was removed for proper visualization.
We proceeded to extract the free graft using the palmaris longus or a flexor carpi radialis hemitendon with 3 mm to 4 mm in thickness and 10 cm in length. In the cases in which the palmaris longus is present, it may be harvested using the same incision performed for the central volar portal.
Under scopic control and using an external guide (SLAM guide, Arthrex) or a freehand approach, the pyramidal bone tunnel was prepared with a 3.0-mm cannulated drill bit (Bio-Tenodesis Screw Kit 3 mm x 8 mm, Arthrex), from the posterior-internal (subcutaneous) edge to the anterior-external edge ([Figure 2]). A straight suture retriever (SutureLasso, Arthrex) was introduced from the dorsal region of the tunnel up to the central volar portal. After enlarging the 4-5 portal and performing a miniarthrotomy, a lunate bone tunnel was prepared in a posteroanterior direction, perpendicular to the long axis of the wrist; a second suture retriever was passed through this tunnel in the posteroanterior direction ([Figure 2]).
Fig. 2 Pyramidal and lunate tunnel preparation.
The free graft plasty was prepared with 4-0, high-strength suture (Fiberloop, Arthrex) at the ends that were loaded into the suture retrievers to pass the plasty through the tunnels ([Figure 3]). The plasty was fixed with a 3-mm x 8-mm interferthence screw (Bio-Tenodesis Screw System) in each tunnel in the anteroposterior direction, sustaining the plasty with traction on both ends; as such, the volar portion of the lunotriquetral ligament was reconstructed with adequate tension. The suture was retrieved through the dorsal aspect of the 4-5 portal to perform a dorsal capsular reinforcement following the direction of the dorsal radiocarpal and radiolunate ligaments ([Figure 4]). Both were fixed on the dorsal edge of the radius through the 4-5 portal, widening its incision until the distal edge of the radius was visible. Fixation was made with a 1.4-mm harpoon (JuggerKnot, Zimmer Biomet, Warsaw, IN, US) or a posteroanterior tunnel with an interference screw. At the end of the procedure, the stability of the construct was evaluated with a palpation hook and the arthroscopic ballottement maneuver ([Figure 5]).
Fig. 3 Passage of the free plasty through the tunnels.
Fig. 4 Reconstruction and fixation of the secondary stabilizers in the distal radius.
Fig. 5 Intraoperative aspects of the clinical case. (A) Central volar portal, reconstruction of the volar portion of the ligament, and fixation with interference screws. (B) Intraoperative endoscopy to identify the correct direction of the tunnels. (C) Suture retriever passing through bone tunnels and plasty recovery on the dorsal side.
Postoperative period
This type of reconstructive surgery is followed by a two-week immobilization period with a dorsal antebrachiopalmar splint. Subsequently, the splint is replaced by an orthosis that enables initial passive joint mobilization exercises. After the sixth week, the orthosis is removed, and the exercise load, increased. Potentiation and proprioceptive work of the extensor carpi ulnaris is emphasized because this is the only muscle able to avoid pyramidal flexion and supination,[10] and it contributes to the dynamic stabilization of the carpus.
Results
Restoration of lunotriquetral ligamentous stability has been observed in all ligamentoplasties performed in cadaveric specimens and in the clinical case, both on the arthroscopic ballottement test and in the evaluation with a palpation hook ([Table 1]).
Table 1
|
Case
|
Ballottement, preprocedural
|
Ballottement, postprocedural
|
Geissler, preprocedural
|
Geissler, postprocedural
|
Distance from the sensory branch of the ulnar nerve (mm)
|
Distance from the posterior interosseus nerve
(mm)
|
Distance from the ulnar neurovascular bundle
(mm)
|
|
I
|
***
|
*
|
IV
|
I
|
7
|
3
|
6
|
|
II
|
***
|
*
|
IV
|
I
|
9
|
4
|
4
|
|
III
|
***
|
*
|
IV
|
0
|
5
|
5
|
5
|
|
IV
|
***
|
*
|
IV
|
I
|
3
|
4
|
3
|
|
V
|
***
|
*
|
IV
|
0
|
9
|
2
|
4
|
|
VI
|
***
|
*
|
IV
|
I
|
11
|
4
|
5
|
|
|
|
|
|
7.33
|
3.6
|
4.5
|
In the postprocedural anatomical dissection of the cadaveric specimens, no iatrogenic lesions were observed in extensor tendons, flexor tendons, or the ulnar neurovascular bundle; in addition, there were no intraoperative fractures or damages to the midcarpal and radiocarpal joint surfaces. The mean distance between significant at-risk structures was of 7.3 mm from the dorsal pyramidal tunnel to the ulnar sensory branch, 3.6 mm from the dorsal lunate tunnel to the posterior interosseous nerve, and 4.5 mm from the volar pyramidal tunnel to the ulnar nerve bundle ([Table 1]).
Our patient presented a satisfactory postoperative improvement in pain and grip strength (31 kg, 81% of the normal values). Six months after the intervention, the score on the QuickDASH was of 14, and the VAS score was 2. Regarding joint mobility of the wrist, a decrease of 10% to 15% was observed compared to the contralateral wrist in flexion-extension and radioulnar deviation.
Discussion
First, the present work proposes an alternative for the minimally-invasive reconstruction of the lunotriquetral ligament and its secondary stabilizers. Secondly, its design tries not only to reproduce the anatomy but also to counteract the pathological and mechanical aspects of the instability of the intercalated segment. Third, the process of development and evaluation of the technique in cadaveric specimens provides safety and efficacy for its clinical application.
The current standard in reconstructive surgery is minimal surgical aggression, and the techniques must meet this requirement. Chronic rupture of the lunotriquetral ligament can be solved with different techniques; however, its reconstruction with a tendon plasty should be the golden standard in selected cases. As such, a similar technique[1] with arthroscopic assistance was used in two patients with satisfactory outcomes. This technique presents three differences. The first is the use of the extensor carpi ulnaris tendon as a donor; in published studies[11] on lunotriquetral stabilization, the palmaris longus or flexor carpi radialis hemitendon is preferred. The second difference is the use of exclusive instrumentation for the technique, which prevents its reproduction. Finally, there was no anatomical study in cadaveric specimens to maximize the protection of at-risk structures.
As in other types of injuries to intrinsic ligaments, the time elapsed since the injury influences the indication of surgical treatment. In cases of acute injuries with a native ligament with healing potential, satisfactory outcomes have been observed in more than 80% of the cases with simpler techniques, including debridement and fixation with Kirschner wires, volar capsulodesis, or direct repair with harpoons.[12] The indication for a ligamentoplasty should be compared with the indication for a lunotriquetral arthrodesis due to the chronic nature of the lesion. For arthrodesis, the publications[13] report pseudoarthrosis rates higher than 50% and a decrease in joint range of motion of up to 40%, which has made it a controversial procedure. This aspect, added to the satisfactory outcomes of ligamentoplasties either with an open approach[14] or arthroscopic assistance,[1] should be considered for treatment indication.
In recent years, an exponential development of wrist arthroscopic techniques has been observed, and the repair or reconstruction of the most important players in ligament stability has been described. As noted in the preliminary study with cadaveric specimens, there are anatomical structures a few millimeters away, and their injury may compromise the outcomes; the posterior interosseous nerve would be at the highest risk of injury during the completion of the lunate tunnel, and, to avoid it, a 4-5 portal expansion and its protection are recommended. Specific external guides should also be considered to avoid iatrogenic damage during the creation of the bone tunnels; in any case, several fluoroscopic projections may prevent iatrogenic injuries. The reported rate of complications decreases after 25 arthroscopies/year and more than 5 years of experience in this type of procedure.[15] For this reason, similar training is recommended prior to the clinical application of the described technique.
In conclusion, arthroscopy-assisted lunotriquetral ligamentoplasty may be an option for the treatment of chronic instabilities with or without loss of the intercalated segment attachment. As in partial scapholunate ligament lesions, most injuries go unnoticed and cause functional limitation; and arthroscopy is an important tool for the diagnosis and treatment. At the moment, these are rare lesions, so further work is required to clarify the best treatment algorithm for them.
