Scapho-Lunate (SL) Ligament injuries are serious injuries to the wrist. The Scapho-Lunate Ligament connects two of the most important bones of the wrist together: the scaphoid and the lunate. The Scapho-Lunate Ligament keeps those small bones of the wrist moving together in a normal, synchronous fashion. Tears of the Scapho-Lunate Ligament can cause significant pain and usually lead to arthritis after 10-15 years, sometimes earlier.
Scapho-Lunate Ligament injuries can occur from either repetitive overuse or from trauma, such as a fall onto the outstretched hand. Scapho-Lunate Ligament injuries lead to pain on the back (dorsum) of the wrist that is worse with activities, especially when putting pressure on the extended wrist, such as when doing a push-up, getting up off of the floor, getting out of a pool, or opening a door.
The diagnosis of Scapho-Lunate Ligament injuries is suspected based on a physical examination performed by a Hand Surgeon. Tenderness over the Scapho-Lunate Ligament and pain about the ligament when extending the wrist makes one suspicious of a Scapho-Lunate Ligament injury. The hand surgeon will perform a “scaphoid shift” test, which attempts to determine whether or not the scaphoid and lunate bones are moving together correctly. A negative test does not mean that the ligament is not affected, only that other supportive ligaments may be intact enough to prevent abnormal motion under the low loads used during a physical examination. On the other hand, a positive scaphoid shift test signifies a significant Scapho-Lunate Ligament injury.
In advanced cases X-rays will reveal a gap between the scaphoid and the lunate. However, in most cases X-rays will not be helpful in diagnosing a Scapho-Lunate Ligament injury. MRI is not very accurate for diagnosing Scapho-Lunate Ligament injuries, even if dye is injected into the wrist joint (i.e. an MR Arthrogram). The best way to diagnose Scapho-Lunate Ligament injuries is by arthroscopy. However, MRIs are usually performed before wrist arthroscopy to rule out other problems outside the joint that the arthroscope can’t see, such as occult ganglion cysts, Kienbock’s Disease, etc.
In mild cases, where the Scapho-Lunate Ligament is “sprained” and not significantly torn, a splint, a steroid injection and avoiding loading the extended wrist for an extended period of time (well over a year) may be enough to quiet things down. Weight-lifting can be performed in a splint that keeps the wrist in neutral position. Knuckle push-ups can be substituted for regular push-ups, or a dumbbell or other device can be grasped that keeps the wrist in neutral position during push-ups. As an aside, although most people perform the bench press and other weight-lifting exercises with the barbell pressing their wrist back into extension, this is poor form, and can lead to wrist problems.
If non-operative management fails to provide sufficient pain relief, the next step is to confirm the diagnosis and to visualize the degree of Scapho-Lunate instability. This is done arthroscopically. The Scapho-Lunate Ligament is arthroscopically visualized, and the degree of gapping and instability between the Scaphoid and Lunate bones is seen and graded with a small probe. Wrist arthroscopy is a quick, minimally invasive out-patient procedure that involves minimal down-time.
If arthroscopy reveals that the Scapho-Lunate Ligament is intact and the scaphoid and lunate bones are stable, then the pain may be coming from “dorsal capsulitis”, an inflammatory condition of the joint lining next to the Scapho-Lunate Ligament that can mimic a Scapho-Lunate Ligament injury. Dorsal capsulitis can be addressed arthroscopically by removing some of the joint capsule (the balloon that surrounds the wrist joint). Removing this piece of joint capsule causes no harm; in fact, this is the same portion of the joint capsule usually removed during ganglion excision. Following this arthroscopic procedure, there is no splinting and activities can slowly be restarted within a week following surgery. If any other problems are found within the wrist joint, they can be addressed arthroscopically or photographed and discussed later if they are too big for arthroscopic management.
If the Scapho-Lunate Ligament injury is due to a traumatic event that occurred within the past 3 months in a young patient, Scapho-Lunate Ligament repair can be considered. Let me state now for the record that anything that is done to treat a Scapho-Lunate Ligament injury has at least a 20% failure rate. Period. Sometimes more. Scapho-Lunate Ligament injuries are still one of the big unsolved problems in Hand Surgery today.
A Scapho-Lunate Ligament repair is performed through an open incision. The Scapho-Lunate Ligament is repaired back to the bone with a small anchor, which looks a lot like the head of a harpoon. It sticks into the bone and has stitches on it that hold the ligament back down against the bone. The Scapho-Lunate Ligament repair is protected by an absorbable screw between the scaphoid and the lunate. This screw absorbs over time and eventually breaks with a disconcerting, but harmless, “pop” a few months after surgery. However, by the time it breaks it has already stabilized the scaphoid and lunate together enough that the ligament has healed, if it’s going to heal.
If there was no traumatic injury, or if it’s been over 3 months since an injury, a Scapho-Lunate Ligament repair will probably fail. As a failed Scapho-Lunate Ligament repair can lead to permanent stiffness, it’s not a surgery that I recommend if the odds of success are poor. In this situation, which is extremely common, if the symptoms are too much to live with a Scapho-Lunate Reconstruction can be performed. I also prefer a reconstruction to a Scapho-Lunate Ligament Repair in patients between the ages of 40-60 years, as stiffness following Scapho-Lunate Ligament repair becomes more common in patients over 40. Reconstruction techniques stabilize the scaphoid and lunate by methods other than a direct ligament repair. The most common reconstruction method is to use a tendon to control abnormal scaphoid motion. There are many different variations of Scapho-Lunate Ligament Reconstruction that have been described. The reason that there are so many techniques is that each of them has at least a 20% failure rate.
My own personal philosophy when all treatments have a significant failure rate is to perform techniques with higher success rates that also have low complication rates. At the current time, until better reconstructive options come along, I prefer to use the Modified Brunelli Reconstruction, which is performed on an outpatient basis. The Modified Brunelli Reconstruction uses a tendon to substitute for the loss of the Scapho-Lunate Ligament. Roughly 1/3 of the Flexor Carpi Radialis (FCR) tendon is separated from the remaining 2/3 of the FCR tendon and pulled through a hole created in the scaphoid. This is then tensioned over the scaphoid and lunate bones and tied down with an anchor to reconstruct a tether between the scaphoid and lunate and reduce abnormal scaphoid motion. After surgery, a short arm cast is worn for approximately 4-5 weeks.
If someone is 55-60 years or older, it may be better to simply remove the scaphoid and perform a Luno-Capitate Fusion, as detailed in the Wrist Arthritis section of this website. This outpatient procedure involves partially fusing the wrist, followed by a cast for 4 weeks. It provides motion similar to what someone this age could expect from a Scapho-Lunate Ligament Reconstruction and the results are more predictable.
Scapho-Lunate Ligament injuries are a complex topic that is still without a predictable solution. We have a good surgical option available, if needed, but no great treatments as of yet. However, if realistic goals are understood, most patients are quite happy with their surgical results.