Scapholunate Ligament Injury
What is a Scapholunate Ligament Injury?
The wrist is a complex joint providing an extraordinary degree of mobility for positioning the hand for tasks. The wrist relies on ligaments to restrain the various bones in the joint from excessive movement relative to each other. If too much force is applied, ligaments can give way, leading to instability of the wrist, poor function, pain, and arthritis with time.
The wrist includes 8 carpal bones that are located distal to the radius and ulna bones of the arm. Together these bones allow complex motions of the wrist. The first row of bones beyond the radius and ulna is called the proximal carpal row and it is comprised of the scaphoid, lunate, and triquetrum bones. The scapholunate (S-L) ligament binds the scaphoid and the lunate bones and is a primary stabilizer of the wrist (Figure 1). It has been said that the S-L ligament is to the wrist, what the ACL is to the knee.
Injury to the S-L ligament is the most common wrist injury and it typically occurs through hyperextension of the wrist from a fall on an outstretched hand or an acute twisting injury. The severity of the injury to the S-L ligament can range from a partial to a complete ligament tear. The method of treatment will depend on both the degree of injury to the S-L ligament and to the timeliness of treatment for the injury, as treatment is most effective when administered early. The goal of treatment is to relieve pain with minimal functional loss.
Injuries that are left untreated can become more painful and restrictive with time. More significantly, injury to the S-L ligament may allow diastasis (widening) between the scaphoid and lunate bones, and rotatory subluxation (mal-alignment) of the scaphoid. Over time, chronic S-L ligament injuries often lead to progressive, degenerative, and arthritic conditions within the wrist.
Signs and Symptoms:
Symptoms from injury to the scapholunate joint may vary in intensity depending on the degree of injury. Upon initial injury, the patient may experience both pain and swelling in the wrist. In more serious injuries a patient may notice increased pain, swelling, a clicking or clunking sensation, weakness, and loss of wrist motion.
In cases that are left untreated, the patient may find that once the initial swelling and pain have diminished, the wrist may have minimal symptoms. However, over time patients may notice pain or discomfort following increased activity or overuse of the wrist. Often, the initial injury is diagnosed when a patient presents with a secondary problem such as carpal tunnel syndrome.
The first step in treating an acute or recent scapholunate injury is to reduce the pain and swelling. This is accomplished using RICE (rest, ice, compression, and elevation) as well as splinting. Your doctor may also prescribe pain or anti-inflammatory medications.
Minor injuries may be treated with a splint or a cast. For more severe injuries, a cast, splint, or brace may be worn until surgery is performed. A significant injury to the S-L ligament is rarely expected to heal with conservative, non-operative treatment.
If conservative options are not effective, surgery may be recommended. The goals of surgical treatment for S-L ligament tears are to restore proper alignment to the wrist bones and to restore the normal tether between the scaphoid and lunate. Many options exist for treatment of a S-L ligament tear. The timing (how recent the injury is) and severity of the injury to the S-L ligament typically determine the appropriate method. Wrist arthroscopy is a diagnostic imaging tool that is usually used in order to evaluate the severity of the ligament tear, the condition of the scapholunate joint, and the health of the surrounding cartilage. In this way, arthroscopy aids in determining the best procedure to restore optimum function to the wrist. The surgeon will take numerous factors into account to determine how to best proceed including: the extent of the injury, the health of existing cartilage and joints, individual needs, and chronicity of the dysfunction.
Acute Options: (Within 1-3 months of initial injury or a chronic partial S-L ligament tear)
1) Acute S-L Ligament Repair with temporary pins or screw:
A patient with an acute injury may undergo wrist arthroscopy to access the severity of the tear, condition of the joint, and health of surrounding cartilage. An acute partial S-L ligament injury (< 3 months old) that demonstrates mild translation of one bone on another, but shows no widening between the scaphoid and lunate, may be treated arthroscopically with debridement of the joint (removal of injured tissue). This may be accompanied by multiple temporary pins (Figure 2) or a temporary screw (Figure 3) to properly align the two bones across the S-L joint and to create an environment to encourage healing. Pins are usually removed at about 8 weeks, while a screw may be left in longer (4-8 months). Rehabilitation with range of motion and strengthening exercises will follow the removal of the hardware.
2) Acute S-L Reconstruction and Capsulodesis:
If diastasis (widening) between the S-L is also present, but a complete tear of the S-L ligament is not found, a direct take down and repair of the ligament using sutures may be required to stabilize the ligament. Tissue from the dorsal wrist, such as the transverse intercarpal ligament, may be used to reinforce the S-L ligament repair. This is referred to as a capsulodesis repair. The surgeon will make a small incision on the top of the wrist, remove the transverse intercarpal ligament from the trapezium while leaving one end anchored at the triquetrum bone, and instead will attach the ligament from the scaphoid bone to the triquetrum bone. The surgeon will reattach the S-L ligament with sutures. Temporary pins or a single screw may be used across the scaphoid and lunate bones to hold the carpal bones in alignment. With a complete S-L ligament tear, direct repair is performed with or without a capsulodesis, and pin or screw transfixation is performed (Figure 4).
Postoperative Protocol: Following surgery the patient’s wrist will be well supported in a splint. Rest, elevation, and ice or a cryo/cuff on the wrist will aid with comfort. At 7-10 days the sutures will be removed and the patient will be fitted with a removable clamshell brace or a cast. Hand and wrist exercises with a therapist will aid in restoration of normal function after surgery. The therapist will advise the patient on slow, steady movements to build both strength and flexibility. Pain medicine should be taken as needed and as prescribed.
A) If temporary pins are used, usually very little or no motion is allowed until the pins are removed to prevent pin breakage. The temporary pins are removed at 8-10 weeks and active and passive progressive motion with a therapist begins.
B) If a temporary screw is used, the patient will begin gentle therapy-assisted active motion to help prevent stiffness at 4-6 weeks. The removal of the screw is dependent upon the type of surgery and the healing. The temporary screw is often left longer than a temporary pin in the wrist to provide adequate time for healing and prevent immediate reinjury.
Chronic Options: (More than 3 months after initial injury)
Although S-L ligament injuries are quite common, the potential adverse effects of high grade partial or total S-L ligament rupture are often underestimated and the injury frequently remains untreated or poorly managed. If the S-L ligament does not heal spontaneously then the scaphoid and lunate may begin to rotate in opposite directions. When this rotation occurs in conjunction with widening of the joint space, the scaphoid and lunate progressively begin to fall out of alignment–causing the adjacent joints additional stress. With time, severe arthritis and SLAC wrist (Scaphoid Lunate Advanced Collapse) may develop triggering increased pain and decreased grip strength. Different degrees of chronic injury to the S-L ligament require varying modes of surgical repair. The overall goals of treatment are to reduce pain and restore function by regaining adequate range of motion and the ability to carry loads without the wrist yielding. This often requires a “salvage” operation.
1) Chronic S-L Reconstruction and Capsulodesis):
In a chronic injury without the presence of widening, the surgeon could align the scaphoid and lunate and use temporary pins or a screw to hold them in alignment. The surgeon may then perform a S-L ligament repair using anchors and/or small screws with attached sutures to secure the S-L ligament back to the areas where it was torn or stretched from. The surgeon may also secure the transverse intercarpal ligament from the triquetrum to the scaphoid to provide a more stable wrist repair. This procedure, known as capsulodesis repair, helps stabilize the scaphoid and lunate and prevent them from rotating back out of alignment.
Postoperative Protocol: The wrist will be immobilized in a short-arm splint for 8-12 weeks following surgery. Sutures will be removed at about 2 weeks. Pins are removed at 8 weeks and gentle active range of motion exercises will be initiated. If a screw was used, motion may begin about 4 weeks. The screw is left for a prolonged period of time, and is not always removed depending on symptoms and x-rays. Full use of wrist is allowed between 4-6 months.
2) Triligament Reconstruction:
If the S-L ligament is beyond repair, yet healthy cartilage exists and the S-L joint remains easily reducible, then ligament reconstruction may be offered. Often the FCR (flexor carpi radialis) or ECRL/B (extensor carpi radialis longis or brevis) tendon can be transferred to recreate the S-L ligament by passing the tendon through the trapezium, scaphoid, and lunate and anchoring the tendon back onto itself (Figure 6). Temporary pins are also used to secure the reconstruction while it heals. While the early results of this procedure appear promising, results can vary between patients, and there are no long-term studies published as of yet. The procedure requires multiple drill holes and tendon passing, as well as an extensive period of immobilization, which prompts many patients to develop stiffness at the wrist.
3) Reduction Association of Scapholunate (RASL):
In a chronic injury with widening between the scaphoid and lunate, translational motion, and static position of the S-L, direct repair of the ligament is no longer an option. One option available is referred to as a RASL (Reduction Association of Scapholunate Joint). In this procedure, part of the scapholunate joint is roughened up to create a bloody surface encouraging fibrous healing to occur between the S-L interval. The surgeon places a screw across the S-L joint to hold the scaphoid and lunate bones in alignment. The scapholunate joint rotates axially on the screw, thus allowing improved movement to the wrist (Figure 8). The screw may be removed somewhere between 1-3 years following surgery depending on the wear characteristics of the screw within the S-L bones. This provides adequate time for the tissue across the S-L joint to form.
Often, in late S-L ligament injury, spurring of the radial styloid can occur and impinge upon the scaphoid causing pain. A radial styloidectomy is a procedure where a small piece of the distal radial tip is removed to provide some relief from radial styloid impingement (Figure 8).
Postoperative Protocol: The wrist will be kept immobilized for 4-6 weeks in a thumb spica splint, at which point the patient will be provided with a removable splint and range of motion will be initiated. Strengthening exercises may begin about 3 months after surgery.
4) Proximal Row Carpectomy (PRC):
When significant arthritis has developed between the scaphoid and distal radius, Proximal Row Carpectomy (PRC) surgery may be an option. This procedure is used to bypass the arthritis that predictably develops between the scaphoid and radius in chronic S-L ligament tears.
PRC is the removal of the scaphoid, lunate, and triquetrum bones (Figure 9). This creates a new joint between the capitate and lunate fossae which generally have preserved/healthy cartilage. This procedure allows for maintenance of about 40 degrees wrist flexion and 40 degrees of wrist extension (although more or less may occur). A radial styloidectomy (removal of the distal radial tip) may also be necessary to reduce arthritic pain (Figure 10).
Postoperative Protocol: The wrist will be splinted for approximately 2 weeks, at which point range of motion exercises will be initiated. Splint protection is worn once motion has begun and is individualized for approximately 2- 3 months after surgery. Strengthening exercises may begin at this time.
5) Four Corner Fusion and excision of the Scaphoid
Four Corner Fusion is considered when the joint and cartilage between the scaphoid and radius have become arthritic. The procedure involves fusing four of the eight carpal bones– the Capitate, Lunate, Triquetrum, and Hamate while removing the arthritic Scaphoid. The cartilage between the bones is also removed and a bone fusion plate is fastened to the top of the four bones with screws, thus holding the bones in alignment relative to one another. Bone graft is packed between the four carpal bones to enhance the fusion. (The removed scaphoid may be used as bone graft.) A radial styloidectomy (where the radial tip is removed) is performed to ensure that the wrist can move without possible impingement (Figure 11). A four corner fusion provides increased strength, decreased pain, and preserved motion of the wrist.
Postoperative Protocol: Patients will be placed in a splint for the first 10 days following surgery. Slow progressive mobilization of the wrist is begun under supervision once x-rays show early bone healing at 4-6 weeks. Therapy is suggested to aid in the process of mobilizing and strengthening the wrist. Most patients experience about 50% of normal flexion and extension of the wrist following this procedure.
6) Full Wrist Fusion
Full Wrist Fusion is often chosen when ‘SLAC’ (Scaphoid Lunate Advance Collapse) occurs or when a chronic S-L ligament injury becomes severely arthritic. If the joint and cartilage of various carpal bones are not healthy, a fusion of the affected carpal bones may be required. It may be used instead of a PRC or 4 corner fusion if strength is more important than wrist motion in one’s occupation or vocation. It may also be used if a PRC or other S-L reconstructive procedure has failed.
A full wrist fusion procedure involves removing the proximal carpal row of bones, placing a wrist fusion plate across the wrist, and securing the plate using screws. Bone graft is packed between the remaining carpal bones of the wrist to assist with full fusion (Figure 12). The removed carpal bones may be used as bone graft, and may be augmented with allograft (cadaver tissue).
Permanent loss of flexion and extension will occur due to the plate and fusion of the bones; however, wrist fusion can be very successful for alleviating pain. In addition, it creates a strong wrist. Although flexion and extension of the wrist will be limited, the wrist will usually be able to fully rotate (palm up/down motion). The plate may require removal after one year.
Postoperative Protocol: Following surgery the patient’s wrist will be placed in a supportive splint until fusion takes place–typically 8-10 weeks after surgery. The patient should rest, elevate, and ice or use a cryo/cuff on the wrist to aid with comfort, and take pain medicine as needed and as prescribed. Gentle range of motion and finger motion exercises will begin immediately following surgery to reduce swelling and prevent stiffness while the wrist is immobilized. At 7-10 days the sutures will be removed and the patient will be fitted with a clamshell brace or cast. A therapist will advise on slow steady movements to build strength and flexibility. Full use is allowed once fusion is obtained.
Overall, the above options may reduce pain and instability of the scapholunate. However, you may expect some degree of wrist flexion or extension loss with reconstructive procedures and complete loss of motion if fusion is elected as currently there is not a perfect scapholunate repair, reconstruction, or salvage procedure. Consult your physician to see which treatment option is best for you.
Note: These instructions are to serve as guidelines and are subject to Physician discretion. Actual progress may be faster or slower depending on the individual.