Rhizarthrosis: definition, causes, symptoms, diagnosis and treatment

By Cristiano Antonino Last updated Jun 14, 2023

Also called trapeziometacarpal osteoarthritis, rhizarthrosis is a particular form of osteoarthritis that affects the carpometacarpal joint of the hand

And, therefore, the joint at the base of the thumb.

It is a degenerative disease of the cartilage of the hand, characterized by moderate pain in the thumb which is prevalent mainly in patients over 50 (especially females).

Diagnosable by means of a simple X-ray, it can be treated both with conservative therapies and with surgery.

Rhizarthrosis, what is it?

Rizoarthrosis, commonly known as “thumb osteoarthritis”, is the most common form of hand osteoarthritis.

Described for the first time in 1937 by Forestier, it concerns 10% of arthritic locations.

It is mainly women who are affected: the incidence is 30% after the age of 50, 90-92% after the age of 80.

Mobile joints, while putting two or more bones in contact with each other like other joints, are characterized by the presence of a particular type of cartilage (called “articular cartilage”) which prevents the bones from “rubbing”, and therefore from being damaged causing pain and strain.

Osteoarthritis occurs when the articular cartilage, due to a series of causes, thins causing the exposure of the underlying subchondral bone, which becomes more susceptible to friction and, therefore, to inflammation.

In the specific case of rizoarthrosis, the trapeziometacarpal joint is affected.

Located at the base of the thumb, between the first metacarpal and the trapezius bone of the carpus, this allows the thumb to flex, extend it and oppose it to the other fingers.

Rhizarthrosis, the causes

There is no single cause behind osteoarthritis.

The pain is caused by inflammation of the bones, which in turn is caused by joint degeneration.

This, thinning, causes the surfaces of the first metacarpal and the trapezius to rub together: the thumb moves and they rub against each other, giving rise to an inflammatory process that can tend to become chronic and be decidedly painful.

There are several causes behind cartilage degeneration

gender: predominantly the female population is affected by rhizarthrosis, especially menopausal women over 55 years of age;
age: with advancing age the risk of suffering from arthrosis of the thumb increases, although it is not impossible to develop it when young;
the genetic and familial predisposition to osteoarthritis: there are numerous genetic diseases linked to cartilaginous degeneration, but the possibility of incurring rhizarthrosis is increased even if there are other members of the family who suffer from it;
history of trauma to the thumb: there are several cases of patients who have suffered trauma to the first toe and then developed rizoarthrosis after even a long time (it often happens among volleyball players, rugby players, basketball players and among who does manual work);
obesity, due to the ability that fat cells have to produce adipokines, hormones that also cause inflammation in the joints.

Rhizarthrosis, symptoms

Rizoarthrosis is often visible to the naked eye: the thumb is swollen, almost deformed.

Although the first symptom, the typical one, is pain (not necessarily intense).

The typical symptoms of rhizarthrosis include:

pain and swelling at the base of the thumb
feeling of soreness, especially to the touch, at the base of the thumb
unusual sounds when moving the finger
difficulty in dexterity, for example when trying to open a jar
stiffness of the affected joint

Pain is a fairly typical pain: initially it is felt only when performing specific movements, then it transforms into a painful form that comes and goes (generally not intense).

Finally it evolves into a fixed pain which, depending on the moment, can be more or less strong.

When the inflammation reaches its peak, however, the pain becomes so intense as to even compromise the nocturnal disorder.

Normally only one thumb is affected (generally that of the dominant limb), but rhizarthrosis can become bilateral over time.

The patient suffering from rhizarthrosis feels pain especially at night.

In many cases, a swelling appears at the base of the thumb caused by the progressive and lateral sliding of the base of the first metacarpal which – gradually losing its relationship with the trapezius – leads to a dislocation.

Rhizarthrosis, the diagnosis

The patient who experiences constant pain at the base of the thumb, especially if associated with joint stiffness, should consult his doctor for further investigations.

The doctor will make a diagnosis by listening to the person’s symptoms, carrying out an objective examination and then a medical history: through specific questions, he will analyze the patient’s family history and lifestyle habits, and will carefully study the reported symptoms.

To confirm your diagnosis, he will then prescribe a radiological examination, which allows you to see any degeneration and thinning of the cartilage.

Rhizarthrosis, the therapy

There is no real cure for rhizarthrosis: the therapies are used to keep the symptoms under control, but there is no remedy against the degeneration of the articular cartilage.

Depending on the severity of the symptoms, a conservative or surgical approach can be adopted.

In both cases, the goal is multiple: reduction of the inflammatory state and swelling, decrease in pain, improvement of joint capacity.

In this way, the patient will be able to regain possession of normal daily gestures.

Normally a non-surgical approach is opted for, reserving the intervention only for those cases in which conservative therapy has not led to any results.

Among the indications that the patient will have to follow, the most effective are:

rest your thumb to reduce inflammation;
apply ice to the base of the thumb 4-5 times a day, keeping it on for 15-20 minutes at a time;
take NSAIDs (non-steroidal anti-inflammatory drugs) as needed;
apply capsaicin-based creams to the skin of the thumb, with anti-inflammatory and analgesic properties;
use special splints at night which, according to studies, reduce pain during the day;
be administered corticosteroids in painful joints by means of direct injections, with a high inflammatory power and recommended when NSAIDs are not effective;
have physiotherapy sessions to stretch and strengthen the muscles and ligaments of the hand and thumb.

If conservative interventions for rhizarthrosis do not give results, surgery becomes the best option.

It will be performed by an orthopedic specialist in hand pathologies, who will be able to choose the best type of intervention.

The possibilities are in fact mainly five:

arthroplasty, which consists in the insertion of prostheses for the reconstruction of damaged joints;
arthrodesis, i.e. the fusion of the articular bone portions affected by the inflammation;
osteotomy, and therefore the realignment of the trapezius and first metacarpal;
arthroscopic trapeziectomy, which consists in the removal of a part of the trapezius carpal bone;
trapeziectomy with ligamentoplasty, which involves the removal of the trapezius carpal bone and reconstruction of the ligaments.

However, there is no cure for rhizarthrosis. It is a chronic disease that gets worse over time and has no cure.

Each therapy is aimed at resolving the painful symptoms and improving the mobility of the thumb.

Rhizarthrosis, how to prevent it

To say it is the Arthritis Foundation of Atlanta: preventing rhizarthrosis is possible.

This can be done by adopting a correct lifestyle, aimed at containing weight: losing weight, if you are overweight, not only reduces the pressure on the joints, but also inhibits the production of adipokines (hormones with an inflammatory action which, from adipose tissue, spread throughout the body).

A diet rich in omega-3 fatty acids decreases the inflammatory state: for this reason, oily fish such as salmon, mackerel, tuna, herring, trout and sardines, chia seeds, flax and hemp, green leafy vegetables and nuts.

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