User:Maartenv/sandbox

Carpometacarpal Osteoarthritis
Carpometacarpal (CMC) osteoarthritis (OA), also known as trapeziometacarpal osteoarthritis or osteoarthritis at the base of the thumb, is a degenerative joint disease affecting the first carpometacarpal joint (CMC1). This joint is formed by the trapezium bone of the wrist and the first metacarpal bone of the thumb. Because of its relative instability, this joint is a frequent site for osteoarthritis. Carpometacarpal osteoarthritis (CMC OA) of the thumb occurs when the cushioning cartilage of the joint surfaces wears away, resulting in damage of the joint.The main complaint of patients is pain. Pain at the base of the thumb occurs when moving the thumb and might eventually persist at rest. Other symptoms include stiffness, swelling and loss of strength of the thumb. Treatment options include conservative and surgical therapies.

Anatomy
The CMC1 joint is a bi-concave convex, synovial joint between the trapezium bone of the wrist and the metacarpal bone at the base of the thumb. This joint is a so called saddle joint (articulatio sellaris) unlike the CMC joints of the other four fingers which are ellipsoid joints. Because of its specific shape, the CMC1 joint allows a wide range of movement of the thumb. Movements possible in this first carpometacarpal joint are: Because of this high mobility, the CMC1 joint is also more unstable compared to the other CMC joints. Because of this instability the joint is more susceptible to be damaged. To remain stable the CMC1 joint has to rely on the surrounding ligaments for support. These ligaments provide the ability to subject high pressure loads, particularly during pinch and grasp manoeuvres. 16 ligaments surrounding the CMC1 joint are identified, which give strength and stability to the joint. Of these ligaments, the deep anterior oblique ligament, also known as the palmar beak ligament, is considered to be the most important stabilizing ligament.
 * flexion
 * extension
 * abduction
 * adduction
 * opposition
 * reposition

Signs and symptoms
The primary and most common symptom in patients with CMC OA of the thumb is pain. Pain at the base of the thumb is mainly experienced when moving the thumb or when applying pressure with the thumb. However in advanced stages of CMC OA, pain might persist at rest. Another prominent symptom is loss of strength of the thumb. Patients struggle to grab or hold an object due to weakening of the thumb. For example tying a knot or holding a saucepan becomes increasingly difficult. If patients present themselves with these kind of symptoms, physicians should also consider De Quervain syndrome, rheumatoid arthritis, or flexor carpi radialis and flexor pollicis longus tendinopathy as a possible cause.

Typical signs of CMC OA can be observed from the outside of the hand. For example, the area near the base of the thumb can be swollen and could appear inflamed. Advanced stages of CMC OA can eventually lead to deformity of the thumb. This deformity, also called a ‘zigzag’ deformity, is characterized by a deviation of the thenar eminence towards the middle of the hand, whilst the thumb phalanges overextend. Also a grinding sound, known as crepitus, can be heard when the CMC1 joint is moved.

Causes
Although the exact cause remains unclear, there is a general consensus among researchers about some of the mechanisms leading to CMC OA of the thumb.

The CMC joint of the thumb is sensitive to wear and tear, making it vulnerable for OA. It is believed that laxity of the ligaments surrounding the CMC1 joint is the main cause of CMC OA. Especially laxity of the most significant ligament, the palmar beak ligament, will lead to joint instability. This instability causes misalignment of the joint bones, causing the bones to rub against each other. The large forces the CMC1 joint has to withstand, are considered to be another cause of CMC OA.

Risk factors
Several risk factors of CMC OA of the thumb are known. Each of these risk factors does not cause CMC OA by itself, but acts as a predisposing factor influencing the process of OA. Risk factors include: female gender, suffering from obesity, repetitive heavy manual labor, familial predisposition and hormonal changes, such as the menopause.

Pathofysiology
CMC OA of the thumb is a degenerative joint disease. Like OA elsewhere in the body, CMC OA of the thumb occurs when the cushioning articular cartilage of the first CMC joint wears away. As a consequence the bare surfaces of the trapezium bone and the first metacarpal bone rub against each other during movement. In reaction of this process the joint bones thicken at the surface, resulting in subchondral sclerosis. Also bony outgrowths, called osteophytes, are formed at the joint margins. Moreover, the gap between the joint bones decreases. In advanced stages of CMC OA, misalignment of the joint bones causes the tendons attached to thumb to force the base of the thumb into radial deviation and extension and the thumb phalanges in hyperextension. As a consequence a ‘zigzag’ deformity becomes visible.

Epidemiology
CMC OA is the most common form of OA affecting the hand. Dahaghin et al. showed that about 15% of women and 7% of men between 50 and 60 years of age suffer from CMC OA of the thumb. However in about 65% of people older than 55 years, radiographic evidence of OA was present without any symptoms. Armstrong et al. reported a prevalence of 33% in postmenopausal women, of which one third symptomatic, compared to 11% in men older than 55 years. This shows CMC OA of the thumb is significantly more prevalent in women, especially postmenopausal women, compared to men.

Classification according to Eaton and Littler
CMC OA can be divided into different stages which show the progression of the disease. A commonly used staging protocol is the radiological staging according to Eaton and Littler. This protocol is an entirely radiological staging system which was introduced in 1973. Four different stages are distinguished on i.a. radiological evidence of synovitis, joint space and capsular laxity.

Stage 1:
 * ‘synovitis phase’


 * slight widening of the joint space


 * articular contours are normal


 * <1/3 subluxation of the joint (in any projection)

Stage 2:
 * There is a significant capsular laxity


 * 1/3 subluxation of the joint


 * Osteophytes, < 2 mm in diameter, are present. (usually adjacent to the volar or dorsal facets of the trapezium)

Stage 3:
 * > 1/3 subluxation of the joint
 * Osteophytes, >2mm in diameter, are present (usually adjacent to the volar and dorsal facets of the trapezium)

Stage 4:
 * Slight joint space narrowing
 * Major subluxation of the joint.
 * Very narrow joint space
 * Cystic and sclerotic subchondral bone changes are present


 * Significant erosion of the scaphotrapezial joint.

Conservative treatment
Patients with CMC OA of the thumb should initially be treated conservatively. Conservative treatment is equal to any non-surgical treatment and includes splinting, activity modification, NSAID medication and injections with corticosteroids.

Surgical treatment
If conservative treatment does not reduce the complaints of patients, surgical treatment is indicated. This might be the case when pain persists or when functional disability remains present after conservative treatment.There are several surgical options to treat CMC OA of the thumb. The aim of the treatment is not to cure the disease but to minimize the complaints and symptoms of patients. Because many different expert opinions about the surgical treatment exist, there are many varieties of surgery, even within one type of surgery. However, there are four types of surgical techniques that are most commonly used. These techniques can be categorized as follows: Throughout the years many clinical trials have been carried out, investigating which technique is superior. The levels of evidence of these studies vary from case reports up to randomized controlled trials and systematic reviews. Most studies focused on pain scores, strength of the thumb, mobility, satisfaction and complications.Until today no significant evidence has been found to claim one treatment is superior to another in short and long term effects. Further investigation is needed but until new evidence is found investigators advice to carry out the most simple treatment with the least complications in the treatment of CMC OA. This means that the trapeziectomy is the surgical procedure of choice for now.
 * trapeziectomy
 * arthrodesis
 * joint replacement
 * osteotomy

Trapeziectomy
The principle of this procedure is the removal of the trapezium. It is one of the oldest surgical procedures and was originally described by Gervis in 1949. Because half of the carpometacarpal joint is removed, the complaints of the patient caused by the OA are gone. Today, four main varieties within this procedure are performed: Claims have been made that one procedure is superior to the other but even until today scientific evidence is missing to support these kind of statements. When pain, grip strength and key and tip pinch strength were examined, investigators could not find a significant difference between the procedures. Investigators say that the trapeziectomy alone is preferred. It is a more simple procedure then the trapeziectomy with TI or LR and tend to have less complications than the trapeziectomy with LRTI. The trapeziectomy is considered a good (and for now considered the best surgical) option to treat stage II to IV CMC-1 OA.
 * trapeziectomy
 * trapeziectomy with tendon interposition (TI)
 * trapeziectomy with ligament reconstruction (LR)
 * trapeziectomy with a combination of ligament reconstruction and tendon interposition (LRTI)

Trapeziectomy
The most simple form of the four variations is the trapeziectomy alone meaning just the trapezium bone is removed without any surgical adjustments. During this procedure the trapezium bone will be removed through an approximately three cm incision along the lateral side of the thumb. To preserve surrounding structures the trapezium will be removed through fragmentation of the bone (the bone will therefore be broken into pieces). A gap is left by the trapeziectomy and the wound is closed with sutures. After the operation the thumb will be immobilized with a cast.

Trapeziectomy with TI
To fill the gap left after the trapeziectomy, a tendon interposition can be performed. The thought is that this technique would have a better outcome in stability and function of the thumb. During this procedure two or three slips of the abductor pollicis longus (APL) are separated of which one is divided at the musculotendinous junction prior to the trapeziectomy. For the TI the tendon of the palmaris longus is used. If absent (in 13% of the population), half of the flexor carpi radialis (FCR) can be used. The tendon is then formed into a circular shape and is attached to the earlier harvested and divided APL slip. The tendon circle is placed in the gap and will be left free stabilized by sutures.

Trapeziectomy with LR
Another technique used to assumable restore stability of the thumb, is a ligament reconstruction after a trapeziectomy is performed. During this procedure the anterior oblique ligament is reconstructed using the FCR tendon. There is a wide variety in techniques to perform this LR, but they all have the similar goal.

Trapeziectomy with LRTI
Like the name already suggests this technique includes a combination of a trapeziectomy with a LR as well as a TI

Arthrodesis
Arthrodesis of the CMC1 joint is a surgical procedure in which the trapezium and the metacarpal bone of the thumb are secured together. Because the joint is fixed, and therefore can not be moved, the complaints of the patient are gone. During the surgery the two bones will be fixated using three K-wires. The use of plates and screws has also been described. The thumb will be positioned in a way it can still perform a pinch grip. Because of the fixation the two bones will fuse together. This will occur usually within four to six weeks.

However, this technique has some disadvantages. The palm of the hand is unable to be flattened, making it difficult to wear gloves or put your hand in a pocket. Because the stress on the CMC1 joint now is divided over the other joints, those joints are more likely to be damaged. Nevertheless this procedure can be used in patients with stage II and III CMC OA.

Joint Replacement
There are several prostheses available for use although they have not been widely successful. The goal is to create a stable artificial joint. Newer prostheses tend to have better results than older ones.

The total trapeziometacarpal joint replacement is a newer arthroplasty which has developed into a cemented and a non-cemented design. The cement acts as a binding factor for fixation of the prosthesis to the host bone.The non-cemented procedure is a good option to treat stage II and III OA and could be better on short-term than the trapeziectomy with ligament reconstruction and tendon interposition (LRTI). But there´s also literature indicating the contrary. The ‘de la Caffiniere’ prosthesis is a cemented total joint prosthesis. De la Caffiniere is one of the most widely used and studied prostheses that can be used in CMC OA. But research shows no improvement of joint stability, thumb strength and range of motion. And high complication rates of loosening, failure and dislocation are seen due to the technical surgery and difficult revisions.

An Artelon CMC spacer is a T-shaped spacer that is used in surgery where he CMC joint is partially removed. Literature notes that this spacer results in less satisfaction compared with trapeziectomy + APL.

Overall, joint replacements are related to long term complications such as subluxation, fractures, synovitis (due to the material used) and nerve damaging. In many cases a second operation is needed to either resect or repair the prosthesis. Also note that usage of a joint replacement is heavy in costs.

The quality of the prostheses is improving and there is reason to believe this will have a positive effect on outcome in the years to follow.

Metacarpal osteotomy
An osteotomy is a surgical procedure wherein bone fragments are modified into a new shape by cutting the bone. During this procedure an abduction osteotomy of the proximal end of the first metacarpal bone is performed. An incision is made over the radial border of the metacarpal bone. A wedged shape bone fragment is removed, causing the distal part of the metacarpal bone to tilt towards its desired position. Postoperative the thumb of the patient is immobilized using a thumb-cast for 6 weeks.

The aim of this procedure is to change the pressure on the joint, so it can function without further damaging the joint. That is why a successful osteotomy requires a CMC1 joint of reasonable condition. Therefore the metacarpal osteotomy should be limited to patients with a stage I-II CMC OA.

Possible complications are non-union of the bone, persistent pain related to unrecognized CMC or pantrapezial disease, radial sensory nerve injury.

Complications
The most common complication after surgery is pain persisting in the thumb. On long term there is a positive pain relief but on short term patients experience pain from the surgery itself. The main complaint is a burning sensation or hypersensitivity over the incision. Some patients develop a complex regional pain syndrome. This is a syndrome of chronic pain with changes of temperature and color of the skin. Non-union after arthrodesis in which fusion of the trapezium and MC1 bone fails, occurs in 8% to 21% of the cases. Pin loosening, infections and nerve damage are known complications after arthrodesis. Subluxation of a prosthesis is a complication where the prosthesis is mobile and is partially dislocated. When the prosthesis is fully dislocated it is called a luxation. Both are painful and need revision surgery so the prosthesis can be repaired or excised. When using a prosthesis over a longer period of time, there is a chance of breaking the prosthesis itself. This is due to mechanical wear. Prostheses might also cause a reaction of the body against the artificial material used in these prostheses, resulting in local inflammation.