Luno-Triquetral (LT) Ligament Injuries
Now that Kobe Bryant suffered a Luno-Triquetral Ligament injury in his wrist, many people are interested in this problem. The Luno-Triquetral Ligament keeps two of the wrist’s bones, the lunate and the triquetrum, aligned and connected to each other so that they move together in a normal, synchronous fashion during wrist motion. Luno-Triquetral Ligament injuries can cause significant pain and can lead to arthritis, but are not as dangerous as the more common Scapho-Lunate Ligament injury. Luno-Triquetral Ligament injuries are also usually better tolerated than are Scapho-Lunate Ligament injuries, usually causing less pain and disability.
Similar to Scapho-Lunate Ligament injuries, Luno-Triquetral Ligament injuries can occur from either repetitive overuse or from trauma, such as a fall onto the outstretched hand or a twisting injury, often due to power tools. Luno-Triquetral Ligament injuries can lead to pain on the back of the wrist that is worse with activities, especially when putting pressure onto 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. They also can cause pain with forearm rotation, such as when using tools or turning a doorknob.
The diagnosis of Luno-Triquetral Ligament injuries is suspected based on a physical examination performed by a Hand Surgeon. Tenderness over the Luno-Triquetral Ligament and pain about the ligament when extending the wrist makes one suspicious of a Luno-Triquetral Ligament injury. A Hand Surgeon will perform various maneuvers to determine whether or not the lunate and triquetrum are moving together correctly.
MRI is not very accurate for diagnosing Luno-Triquetral Ligament injuries, even if dye is placed into the wrist (i.e. an MR Arthrogram). The best way to diagnose Luno-Triquetral Ligament injuries is by arthroscopy. However, MRIs are usually performed before arthroscopic surgery to make sure that there aren’t any other problems outside the wrist joint that the arthroscope can’t see, such as occult ganglion cysts, Kienbock’s Disease, etc.
In mild cases, when the Luno-Triquetral Ligament is ‘sprained’ and not significantly torn, immobilization using a splint or a cast, a steroid injection and avoiding loading the extended wrist for an extended period of time (often 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 bar pressing their wrist back into extension, this is poor form, and may 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 Luno-Triquetral Ligament instability. This is done arthroscopically. Wrist arthroscopy is a minimally invasive out-patient procedure that involves minimal down-time. Following wrist arthroscopy, the wound should be kept clean and dry for 24 hours. After 24 hours the dressings can be removed and the incision can get wet in the shower. Blot it dry. There are no stitches to remove (they’re buried and absorbable). There’s a piece of tape over the wound. The tape will fall off when it’s ready. The longer it stays on, the nicer the final wound may look. Please don’t submerge the incision under water (like swimming, or putting your hand under water) for 10 days after surgery.
If the Luno-Triquetral Ligament tear was recent (which is admittedly unusual), the unstable torn ends of the ligament are arthroscopically debrided (shaved down) and an absorbable screw is placed between the lunate and triquetrum. This screw often provides stability and pain relief. A cast is worn for 6 weeks after surgery. 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 lunate and triquetrum together enough that the ligament has healed, if it’s going to heal. This arthroscopic treatment has approximately an 80% success rate. As for Scapho-Lunate Ligament injuries, there is a 20% failure rate for all surgical treatments of Luno-Triquetral Ligament injuries.
More commonly, the Luno-Triquetral Ligament tear has been going on for a period of time. In these cases, the Luno-Triquetral Ligament usually won’t heal. Some people have long ulna bones (the long bone on the pinky side of the forearm) that repetitively push against the triquetrum, injuring the Luno-Triquetral Ligament through excessive wear and tear. In these cases, shortening the ulnar bone takes the stress off of the Luno-Triquetral Ligament.
However, the main reason to shorten the ulna is because shortening the ulna tightens up the ligaments that originate from the ulna and attach to both the lunate and the triquetrum. Tightening up these other ligaments provides stability to the Lunate and Triquetral bones, and usually relieves the symptoms of Luno-Triquetral instability. In order to tighten up the ligaments about the Luno-Triquetral joint, the ulnar shortening has to be performed in the middle of the ulna bone, in its shaft. This is an outpatient procedure that involves removing a few millimeters of bone from the center of the ulnar shaft. A plate is placed to protect the ulna while it heals, which takes approximately 3 months. Many hand surgeons, including myself, believe that Ulnar Shortening is the most predictable long-term operation for Luno-Triquetral Ligament. This procedure has a reported success rate of 81-84%.
Ulnar Shortening Osteotomy
Following this surgery, a cast is worn for 6 weeks, and then a removable brace is used until the bone is fully healed. The main drawback to this procedure is that it sometimes takes over 3 months for the ulna to heal. Often, a bone stimulator is used to speed up the healing process. A bone stimulator is a painless device applied 20 minutes a day the operative area. Most activities, including many sports, can be restarted without the bone fully healed on X-ray.
If the Luno-Triquetral Ligament injury is very severe because the secondary, back-up ligaments around it have also torn, or if the Luno-Triquetral Ligament injury has already led to arthritis, the wrist is treated with a Luno-Capitate Partial Wrist Fusion, the same procedure used to treat wrist arthritis (please see the ‘Wrist Arthritis’ section of this website). Luno-Capitate Fusion is an outpatient procedure that involves fusing the lunate and the capitate together. When performed to treat Luno-Triquetral Ligament injuries, both the triquetrum and the scaphoid bones are removed. A cast is worn for 3-4 weeks and then Hand Therapy is begun. This is a predictable procedure that works very well for advanced wrist problems, including arthritis.
The good news about Luno-Triquetral Ligament injuries is that they are usually not as serious as Scapho-Lunate Ligament injuries. An injection and immobilization is often all that is needed. However, if problems persist, there are a number of outpatient surgeries that can provide relief.