Rhizarthrosis

Rhizarthrosis: what’s that?

Rhizarthrosis (arthrosis of the saddle joint of the thumb)  is one of the very most common arthrosis diseases.

The saddle joint of the thumb is the thumb joint closest to the wrist. Thanks to its unique joint form (ball-and-socket joint principle), the saddle joint of the thumb enables extremely complex rolling-sliding movement. Occasionally, rhizarthrosis is also incurred as a component of finger polyarthrosis, which then affects several finger joints.

As for all types of arthrosis, in case of full cartilage loss, bone-to-bone contact with pain and restricted freedom of movement results.

Rhizarthrosis symptoms

The typical symptoms of arthrosis of the saddle joint of the thumb are pain in the base of the thumb, incurred when gripping and during movements involving the thumb. Initially, pain only exists during movement. Often, the pain is so pronounced that those affected – mostly women aged 50–60 – drop items when gripping them. This so-called letting go pain occurs frequently accompanied by rest pain and is an indicator of advanced arthrosis.

Cause of rhizarthrosis

Normally, the precise cause of arthrosis of the saddle joint of the thumb is not known. Disposition, accidents and mechanical overburdening are viewed as the most frequent causes.

Due to its special mobility and the “hypermobility” required for this, the saddle joint of the thumb appears to be generally prone to the emergence of an arthrosis. As women are in particular affected after the menopause, the reduced tautness of the joint (laxity) appears to be a causal factor for the emergence of rhizarthrosis.

Rhizarthrosis diagnosis

Targeted case history provides the basis for diagnosis. Often when looking at the thumb, a swelling of the base of the thumb (area of the saddle joint of the thumb) attracts attention. When examining by palpating, high tenderness is shown in the anatomical snuffbox (foveola radialis) which intensifies if the thumb is moved using external pressure (Grind and Glickel test). X-ray, computed tomography (CT) and possible magnetic resonance imaging (MRI) are used to confirm the diagnosis.

How can the progress of a rhizarthrosis be prevented?

Although arthrosis of the saddle joint of the thumb cannot be reversed, its pain symptoms can be reduced nonetheless.

During the acute inflammatory phase, it is necessary to wear special supports such as the BORT RhizoFlex® thumb ring brace, BORT Generation thumb splint or BORT SOFT long thumb splint. By wearing thumb splints or braces, both the base of the thumb and the remaining stressed thumb and hand tendon and capsule structures can be relieved.

Moreover, overstress of the thumb and hand should be avoided, e.g. via the use of an ergonomic computer keyboard or a so-called “vertical mouse”. Generally speaking, sustained rotational and pressure movements – such as excessive Smartphone use with the damaged thumb – should be avoided.

Following heavy strain, the saddle joint of the thumb can be prophylactically loosened and mobilised  with targeted finger and hand exercises. During the acute phase, cold or heat poultices can contribute to symptom relief.

What therapy options are available for rhizarthrosis?

Depending on the stage of the arthrosis, conservative treatment methods and/or an operation can be applied.

Conservative treatment

Normally, treatment begins with ointments with anti-inflammatory medication or substances to stimulate the blood flow. Combination with immobilisation of the thumb using a thumb-wrist support or a thumb splint is important.

If these measures do not suffice, both the administration of cortisone compounds directly into the joint and the injection of hyaluronic acid or autologous conditioned plasma (ACP) – extracted from own blood – can become necessary. In principal, the complete recovery of damaged or worn cartilage via conservative treatment is not possible.

Operative treatment

Depending on the extent of the damages, an operation to preserve the joint and maintain functionality can make sense. This improves the joint mobility due to removal of part of the bone. An artificial joint is also an option for older people or rheumatism patients.