The study design was approved by the Institutional Review Board of our institute. All methods were carried out in accordance with relevant guidelines and regulations.
Study protocol
A fall to an outstretched hand is a common cause of wrist injury. With radial wrist pain, initial standard radiographs of the wrist and hand are taken to rule out possible bony or ligamentous injuries. If the patient presents with tenderness around the scaphoid, a scaphoid fracture is initially suspected. If plain radiographs do not reveal a significant fracture of the scaphoid or around the radial wrist, a detailed imaging examination is warranted.
A stability test would not be accurate enough to reveal the instability of the wrist in an acute state after injury due to wrist pain and swelling. In addition to the routine radiographs of the wrist, we prefer to perform a computed tomography (CT) scan of the wrist if any carpal occult fracture or any undetected fracture is still suspected (Fig. 1). If no definite fracture can be identified on CT, physical examination strongly indicates a significant injury, repeated physical examinations and radiographs during the period of conservative treatment are important [9, 10]. Attention should be paid to the possibility of undetectable scaphoid occult fracture in the initial CT images or the possible transformation of scaphoid bone bruising to occult fracture. The immobilisation of the wrist would be a helpful treatment in the conservative treatment period to help control swelling and reduce pain.
During follow-ups, physical examinations play an important role in the diagnosis of instability. Tenderness around the scaphoid, especially at the volar aspect, would be a hint of dynamic instability.
Patients with dynamic radiocarpal instability may complain about pain and weakness during activity, and sometimes even at rest. Clicking during wrist motion may possibly be observed. During the scaphoid shift test by applying pressure on the patient’s scaphoid tubercle and moving the patient’s wrist from ulnar to radial deviation, subluxation of the scaphoid and elicitation of pain may be noted [11]. In addition, a carpal stability test is performed by holding the scaphoid between the examiner’s thumb and index fingers and moving in the dorsal and volar directions relative to the radius. Pain and increased laxity compared to the healthy contralateral side would be noted in patients with dynamic radiocarpal instability.
Indications
-
1.
Patients with dynamic radiocarpal instability, presenting with radial wrist pain and a positive carpal stability test showing apparent laxity compared to the other side.
-
2.
Patients with RSC and LRL ligamentous laxity without apparent tears or avulsions.
Contraindications
-
1.
Patients with immunologic diseases, such as rheumatoid arthritis, should be excluded because the ligamentous pathogen is generally around the wrist and not in the specific RSC and LRL ligaments.
-
2.
Patients with apparent carpal ulnar translation as they should be suitable for undergoing ligament reconstruction or a focal arthrodesis procedure.
-
3.
Patients with wrist degeneration as they should be suitable for undergoing wrist total/focal arthrodesis or other salvage procedures.
-
4.
Patients with radial-sided pain from other causes, such as scaphoid or other wrist fractures, tenosynovitis, or an acute stage of soft tissue swelling.
Surgical techniques
We prefer that patients undergo under general anaesthesia while performing arthroscopy on the patient’s wrist in a relaxed state and use an arm pneumatic tourniquet.
Patients with dynamic carpal instability would have a lax wrist so that the scaphoid may be displaced over the scaphoid fossa if the wrist is held in a semi-flexed position in the traction tower. A displaced scaphoid would make it difficult to insert the arthroscope into the 3–4 viewing portal. Manually pushing the carpal bones backwards could normalise the radiocarpal alignment in the anteroposterior direction to facilitate the arthroscope entering the radiocarpal space.
During arthroscopy, the intraarticular structures of the proximal and mid-carpal joints should be checked with a setup of standard 3–4, 6R, and midcarpal (radial and ulnar) portals. The concept of the Mayfield injury mechanism indicates the force of injury from the radial to the ulnar side of the wrist. Therefore, the RSC/LRL and scapholunate (SL) joints should be carefully checked to identify any tear injuries of the RSC/LRL or SL interosseous ligaments. The use of a probe to hook the SL interval to check its tightness and evaluate the laxity of the RSC/LRL ligaments is helpful. If there is any significant SL dissociation, it can be identified during previous image studies and physical evaluations.
In case of findings of lax RSC and LRL ligaments, thermal shrinkage should be performed. It is appropriate to set the 4–5 portal as the viewing portal and the thermal probe in the 3–4 (or 1–2) portal. A thermal tensioning of the RSC and LRL ligaments in the radiocarpal joint is then performed. In the midcarpal joints, the thermal tensioning of the RSC midcarpal portion, as well as the volar wrist capsule, is also performed. An Oratec Micro-TAC-S probe (Oratec Interventions, Menlo Park, CA) for thermal management, with the energy set at 67 °C and 40 W is used. The probe is gently swept over the ligaments. After thermal shrinkage, a switch stick into the interval between the RSC and LRL ligaments is inserted. The switch stick bluntly protrudes toward the skin. After ensuing that the switch stick is directly against the skin without any interposed soft tissue structures, an incision is made in the skin at a position tented by the stick to allow the stick to come out of the skin.
The arthroscope sheath is set onto the switch stick from the volar side, and directed into the radiocarpal joint along the switch stick. It is then forwarded dorsally until the sheath comes out of the dorsal wrist skin. Subsequently, the switch stick is removed, and a string of vessel loops from the arthroscope sheath opening on the dorsal wrist id insert. The vessel loop is passed through the sheath canal to exit the sheath opening on the volar wrist. The sheath is removed, and the vessel loop is retained with its two sides protruding from both the volar and dorsal wrist skin. The route of the vessel loop indicates the interval between the RSC and LRL ligaments (Figs. 2 and 3).
The traction force is then released, and carpal stability is tested. If stability is improved to a level similar to that of the contralateral healthy side, the vessel loop is removed and the tensioning procedures are completed.
If the test still shows radiocarpal instability or the patients perform high-demand hand labour, an open tensioning surgery could be performed. To perform open tensioning, we prefer using a zigzag incision over the flexor carpi radialis (FCR), centred on the volar vessel loop tail (Fig. 4). The dissection would be very straightforward, where a deeper incision along the vessel loop is made as the FCR is retracted ulnarly, ensuring not to injure the radial artery. Opening the FCR tendon sheath would be helpful in providing a good and wide operative field. The vessel loop should penetrate deep into the periarticular fat tissue, and pushing away these fat tissues around the vessel loop with a Freer elevator would be of help to reveal the ligamento-capsule structure. The RSC ligament is on the radial-distal side of the vessel loop, and the LRL ligament is on the ulnar-proximal side. The use of the probe or a Freer elevator for palpation can help in detecting the outer margin of the RSC and LRL ligaments and the space of Poirier, which is toward the distal part of the RSC/LRL interval.
We use 2–0 non-absorbable (Ethibond 2–0; Ethicon USA) sutures, with one suturing both the RSC and LRL ligaments together proximal to the vessel loop and another suturing the two ligaments distal to the vessel loop. The two sutures are tied separately to tighten and close the interval of the RSC and LRL ligaments and the space of Poirier. Thereafter, the suture strings of the two ties are tied together to tighten and tension the RSC and LRL ligaments (Fig. 5). After the suture tensioning procedure, the stability is checked, and the radiocarpal instability can be improved. When closing the wound, if the FCR sheath is open, it is repaired with absorbable sutures. The skin is then closed using 4–0 nylon sutures.
Below are some guidelines for the surgical techniques used in this study.
-
1.
In the open approach for suture tensioning, the vessel loop is set between the RSC and LRL ligaments. However, the outlying margin is difficult to identify. The use of the probe helps to identify the direction of the ligament fibres and the general margin. There is also a risk of injury to the RSC and LRL ligaments if the surgeon tries to remove the fascia tissue after the periarticular fat tissues have been removed.
-
2.
The direction of the RSC and LRL ligaments should be more parallel to the wrist crease direction than to the forearm axis from the perspective of the open wound field. Therefore, the RSC ligament should be on the radio-distal side of the vessel loop and the LRL ligament on the ulnar-proximal side of the vessel loop.
-
3.
There is a mid-carpal portion of the RSC ligament, and the space of Poirier is also located close to it. As the proximal suture is just proximal to the vessel loop, which comes out from the radiocarpal joint, the distal suture should be further away from the vessel loop to grasp the mid-carpal portion of the RSC ligament entity.
Postoperative management
After surgery, a short-arm splint with the wrist at 0o of flexion was used for 6 weeks. Subsequently, gentle wrist range of motion (ROM) exercises were initiated. Strengthening and gradual return to normal activities were allowed 3 months after surgery.
Postoperative assessment
Follow-ups were arranged once every 2 weeks for the first month after surgery, and once every month thereafter for at least 4 months. Additional follow-ups were performed, if indicated. A follow-up 6 months later and yearly thereafter was then conducted.
Functional outcomes were evaluated during follow-ups beginning at 3 months postoperatively. During that time, the scaphoid shift test was performed, and the radiocarpal joint stability was checked. Pain level was evaluated using the visual analogue scale (VAS) for pain (0, no pain; 10, worst pain) at rest, during activity, and active ROM. The Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH) score [12] and the returned level of activity were recorded based on a self-reported questionnaire.
Statistical evaluations
The pre- and postoperative functional results were compared and analysed using the Wilcoxon signed-rank test. The significance level was set at p < 0.05. All statistical analyses were performed using SPSS software (IBM SPSS Statistics for Windows. Version 24.0. Armonk, NY: IBM Corp, 2016).