What is SLAC Wrist?
If someone is facing continuous weakness of wrist joint which leads to advanced arthritis of midcarpal joint and radio carpal joint then is referred as SLAC wrist. SLAC wrist first shows its affect in radio scaphoid joint and then causes problems in capitolunate joint. Scapholunate advanced collapse (SLAC) of the wrist is a very common case of degenerative arthritis affecting the wrist. The most prominent signs of SLAC wrist are the injury in scapholunate ligament or scaphoid which spreads out radially in the wrist.
- Osteoarthritis of wrist is usually caused as a result of SLAC wrist.
- SLAC wrist follows a very definite pattern in terms of pathological and radiographic prints.
- The case is SLAC wrist can be easily diagnosed and monitored during the treatment with the help of imaging techniques.
The risk of Scapholunate advanced collapse (SLAC) is more in cases of men than women and especially those who are involved in lot of physical labor. It usually affects the wrist of your dominant hand. SLAC wrist is known to affect people in the age group of 19 to 82 years. Periscaphoid is associated with 95 percent of diseases related to wrist degeneration. About 57 percent of the cases of periscaphoid arthritis lead to SLAC wrist.
What are the Causes of SLAC Wrist?
The condition of SLAC wrist can be caused by many diseases. Osteoarthritis of the wrist reduces the usability of your hand and causes serious pain. Wrist osteoarthritis usually leads to scapholunate advanced collapse wrist or SLAC wrist which is caused by traumatic injury to the scapholunate ligament. It can also result from scapholunate non-union advanced collapse (SNAC), calcium pyrophosphate dehydrate (CPPD) crystal deposition disease, midcarpal instability, idiopathic avascular necrosis of scaphoid, perilunate dislocation, intra-articular fractures involving the radioscaphoid or capitolunate joint.
- Diseases of wrist like Scaphoid nonunion advanced collapse (SNAC), scapholunate dissociation with rotatory subluxation of the scaphoid can cause SLAC wrist.
- Intra-articular fractures, midcarpal instability can also cause SLAC wrist.
- Preiser disease
- Kienböck disease
- Arthritis associated with inflammation like that caused in the crystalline deposition disorders of gout and CPPD is also a reason for SLAC wrist.
- Primary degenerative arthritis
- Degeneration of the capitolunate may cause SLAC wrist.
What are the Stages in SLAC Wrist?
Specialists and surgeons use Watson staging system to analyze the condition of SLAC wrist:
Stage I SLAC wrist: Articulation osteoarthritis affecting radial styloid and the scaphoid.
Stage II SLAC wrist: Osteoarthritis involving complete radio scaphoid articulation.
Stage III SLAC wrist: Osteoarthritis involving capitolunate articulations and radio scaphoid.
Stage IV SLAC wrist: Osteoarthritis involving radio carpal and intercarpal articulations with or without distal radio ulnar joint (DRUJ).
Keep in mind that the joint of the radio lunate is mostly conserved as far as the very last stage of SLAC wrist.
What are the Signs and Symptoms of SLAC Wrist?
Below mentioned are the signs and symptoms of SLAC wrist:
- Unable to lift of move heavy objects with wrist could be a sign of SLAC wrist.
- Pain in the scapholunate interval region is a symptom of SLAC wrist.
- Continual weakening of affected hand.
- Stiffness in wrist is also seen in SLAC wrist.
What Tests are Conducted to Diagnose SLAC Wrist?
SLAC wrist can be easily diagnosed using Imaging techniques like computed tomography (CT), radiography, magnetic resonance imaging (MRI) etc… It also helps in observing the condition for the purpose of treatment.
Physical Exam for Diagnosing SLAC Wrist
The physical exam for diagnosing SLAC wrist involves:
- Scapholunate ligament tend to get tender dorsally.
- Reduced wrist Range of movement or ROM.
- Reduced gripping strength.
MRI (Magnetic Resonance Imaging), Computed Tomography (CT) Scan to Test SLAC Wrist
The MRI and CT scans for SLAC wrist will show:
- Articular surface usually becomes very thin around the proximal scaphoid.
- Scaphoid facet of capitolunate joint and distal radius along with synovitis in midcarpal and radio carpal joints.
Once the tests are conducted and the disease is confirmed then the specialist doctors will use the Watson staging system to categorize the SLAC wrist. This will help in effective treatment for SLAC wrist.
What are the Treatment Options for SLAC Wrist?
Non-Surgical Treatment for SLAC Wrist
The early non-surgical treatment procedure for SLAC wrist involves nonsurgical treatment. It involves reduced functionality of wrist along with corticosteroid injections, anti-inflammatory medication and splints. If the treatment fails to show any improvement, surgical treatment procedures are recommended.
Surgical Procedure for Treating SLAC Wrist
Limited Wrist Fusion or SLAC Reconstruction Surgery for SLAC Wrist
A SLAC reconstruction is a surgical method for SLAC wrist involving excision and fusion of the hamate, lunate, capitate and triquetrum. In this surgery two incisions are created with a lazy S, or a central longitudinal cut in the distal radio carpal joint. A cut is created through tensor retinaculum in the surgery for SLAC wrist. To get rid of the pain, the end of the posterior interosseous nerve located in the fourth extensor compartment is removed. The wrist capsule is cut to allow opening of the capitolunate joint. The scaphoid is removed surgically through piecemeal process. The surgery involves removal of articular cartilage and subchondral bone from the hamate, lunate, capitates and triquetrum. It is necessary to be very careful about ensuring intercarpal intervals and anatomic relationship. Cancellous bone is derived and developed from the proximal ulna, the distal radius or iliac crest.
The surgery involves correction of Lunate dorsal intercalated segment instability (DISI) for which 5 percutaneous Kirschner wires (K-wires) are required in the process. Out of the five wires, two are pierced through the capitate into the lunate, one into the hamate, on through triquetrum into the lunate, and last one through the triquetrum into capitate. Cancellous bone graft is perfectly placed in the space where 4 bones intersect each other.
In this process a long arm splint is inserted into the wrist which is removed after a week and is substituted by a long arm cast, which is left for a period of next 3 weeks. This is followed by placing a short arm cast for a time period of next 2 to 4 weeks. Once it is ensured that fusion of the bones has completed with radiographs, the cast and wires are taken away.
Many new methods have also developed for 4 quadrant fusion involving use of intercalary screws and a dorsal carpal plate especially designed for the purpose of fusion. The new methods are comparatively costlier and it needs to be seen how much improvement they can provide. However with better fixation it is possible to use short arm cast which can overcome the limitations of wrist ROM (Range of Movement) therapy.
Proximal Row Carpectomy or PRC Surgery For Treating SLAC Wrist
The process of proximal row carpectomy (PRC) for treating SLAC wrist involves surgical removal of the proximal row of wrist bones to facilitate articulation of the capitate placed in the lunate fossa. It is important that the surface of capitate articular and lunate fossa is kept free of pathology. This method for treating SLAC wrist works perfectly for the cases limited to the radio scaphoid joint. PRC is an excellent treatment option resulting in best motion (regular arc 71 degree) but can be associated with pain in wrist during movement. This procedure is usually applicable in the stage I and not in stage 2 SLAC wrist. If it does not work then conversion to wrist arthrodesis becomes necessary.
This method involves incision of transverse of longitudinal type for retraction of extensor tendons and extension of longitudinal capsulotomy ulnarly or radially after identification of capitates followed by inspection of articular surface. The process is not recommended if there are any capitate degenerative changes. Once it is ensured that lunate fossa and capitate articular surface does not have any pathology, once can proceed with excision of triquetrum, lunate and scaphoid. There are no changes made to radioscaphocapitate and long radiolunate ligaments. After collapsing the wrist, the capitates head is placed in the lunate fossa. In case of presence of impingement between the trapezium and radial styloid, radial styloidectomy is usually recommended. The capsulotomy cut is closed using snug.
After the surgery, one can start ROM exercises after a period of 4 weeks from surgery and further heavy exercises must be avoided for atleast three months post-surgery.
Total Wrist Arthrodesis Surgery for Treatment for SLAC Wrist
Total wrist fusion surgery for treating SLAC wrist (see the images below) is helpful in getting rid of pain but results in reduced functionality of wrist making it hard for them to carry out routine activities. Moreover complete pain removal is not guaranteed in this procedure.
The procedure starts with central making a longitudinal incision in the dorsal cavity down to the middle finger metacarpal to distal radius. Then subchondral bone and articular cartilage are surgically removed and separated from the radio lunate, radio scaphoid, scaphocapitate, lunocapitate, and carpometacarpal joints of middle finger. Additionally it may also involve opening of index finger carpometacarpal joint for fusion. Cancellous bone grafting further requires radial metaphysic.
In the method of total wrist arthrodesis for treating SLAC wrist a fusion plate is inserted along with grafting of bone in the midcarpal, radio carpal, and carpometacarpal fusion sites. Screws are used to keep the fusion plate in its place along with re-approximation of Periosteal and capsular flaps. Initially a short arm splint is used until fusion is confirmed using radiographs. It generally takes 6 to 8 weeks for the fusion to take effect.
Total Wrist Arthroplasty Surgery for Treating SLAC Wrist
Total wrist arthroplasty for treating SLAC wrist can also be used instead of diffuse arthrosis of the wrist. This is usually recommended in case of rheumatoid arthritis or presence of bilateral disease. In case of bilateral disease the treatment involves combination of contralateral total wrist fusion and wrist arthroplasty. This procedure has been used successfully in many cases but there is always a risk of implant loosening and wear of the components.
What is the Recovery Period/Healing Time for SLAC Wrist?
The recovery period/healing time for SLAC wrist depends on a lot of parameters like mode of treatment (surgical or non-surgical), severity of disease etc… Thus you must refer to your doctor to find out the recovery time in your case. Also you can seek answers for other precaution related queries.
How to Prevent the Occurrence of SLAC Wrist?
The disease is caused by the wrist injury which is an unfortunate accident and can occur to anyone without any intimation. Thus it is hard to prevent SLAC wrist but surely you can take following preventive measures:
- Make your bones strong in order to prevent SLAC wrist. You can get strong bones by taking the recommended amount of Calcium in your diet. It is 1,200 milligrams per day for women with age more than 50, or 1,000 milligrams per day for normal adult. These are minimum amounts that you need..
- Reduce the chances of falling at your home to prevent SLAC wrist. As the disease is caused as a result of injury in the wrist which usually occurs when you accidently fall forward. Thus if you take measures like wearing shoes with good grips, having grab bars in
- Wear protective gear during athletic activities for prevention of SLAC wrist. Always wear protective gears as a safety measure while you are involved in high-risk activities like snowboarding, football and other such games.
- Never ignore ergonomics. For the individuals who spend a lot of time typing on keyboard, it is necessary to help your hands stay in a relaxed position for preventing SLAC wrist. You can go for an ergonomic keyboard for more comfort.