Definition of rhizarthrosis – arthritis of the base of the thumb
Arthritis of the base of the thumb, also called rhizarthrosis, is wear of the cartilage at the joint between the trapezium bone and the base of the first metacarpal bone. Rhizarthrosis is the most common form of hand osteoarthritis. The presentation of rhizarthrosis is pain in the thumb.
Video of treatment of rhizarthrosis – osteoarthritis of the base of the thumb:
Diagnosis of arthritis of the base of the thumb – rhizarthrosis:
Rhizarthrosis manifests itself by pain, usually gradual, in the base of the thumb, which occurs spontaneously. The pain of thumb osteoarthritis is particularly incapacitating as it makes it difficult to seize and hold objects with the thumb. To determine which rhizarthrosis surgery is the best suited, a thorough clinical and X-ray examination will make it possible to qualify exactly the type of thumb arthritis encountered. There are indeed different types of rhizarthrosis that vary in the intensity of thumb osteoarthritis as well as its extent.
The preoperative clinical examination of the rhizarthrosis should aim at:
- looking for pathologies associated with rhizarthrosis: carpal tunnel, trigger finger;
- assessing pre-operative mobility of the thumb's articular chain as a whole, as thumb osteoarthritis may affect the various joints: trapeziometacarpal joint, metacarpophalangeal joint, interphalangeal joint
- assessing the thumb’s pinching strength with the Key-pinch test; this rhizarthrosis examination also makes it possible to look for instability in the metacarpophalangeal joint frequently associated with advanced forms of rhizarthrosis.
The examination of the rhizarthrosis is then completed by the analysis of the thumb’s x-rays that gives an appreciation of the degree of wear in the trapezium bone, the extent of subluxation of the first metacarpal bone’s base, and possible damage to the scaphotrapezotrapezoidal (STT) space. STT damage associated with rhizarthrosis is called peritrapezial osteoarthritis.
After a clinical and radiographic examination of the thumb allowing the type of rhizarthrosis to be specified, the most suitable hand surgery for your condition can be determined.
Treatment of rhizarthrosis - thumb arthritis:
The primary objective of this treatment, whether it be medical initially or surgical, is to end the pain in the thumb.
For early forms of rhizarthrosis, the first line medical treatment is a combination of slow-release corticoid injections and night rest orthosis. This medical treatment can be efficient to some extent, temporarily, in early forms of rhizarthrosis. Unfortunately the result of medical treatment is often disappointing in advanced forms of osteoarthritis, which is when thumb surgery is justified.
There are different types of rhizarthrosis surgery: thumb prosthetics, open trapeziectomy-ligamentoplasty-interposition-suspension surgery and partial trapeziectomy using thumb arthroscopy.
In early forms of osteoarthritis of the thumb that resist medical treatment, arthroscopic trapeziectomy is an appropriate procedure whose comparative advantage over other surgical techniques is to greatly shorten recovery whilst preserving thumb length and mobility.
More severe forms of rhizarthrosis with advanced marginal osteophytosis (bone spur) and bone wear associated with a subluxation will be beyond arthroscopy and the treatment of rhizarthrosis will sort to two alternatives:
- Hand arthroplasty surgery with a trapezio-metacarpal prosthesis; the thumb prosthesis implies delicate surgery whose benefit is a short recovery that takes approximately 2 months and involves 3-week removable immobilization. The downside of this thumb prosthesis-based rhizarthrosis treatment is unfortunately that in time the prosthesis wears out, all the more rapidly if used intensively.
- The second possible surgical procedure for advanced rhizarthrosis is trapeziectomy-ligamentoplasty-interposition-suspension surgery. The disadvantage of this hand surgery, which is common for rhizarthrosis, is longer recovery, spread over 4 to 6 months involving a 6-week long immobilization by removable orthesis. The advantage of this rhizarthrosis surgery is that it is durable and its effects are permanent.
Arthroscopic surgery of rhizarthrosis
The surgical treatment of rhizarthrosis by arthroscopic trapeziectomy is thus particulary advisable in early rhizarthrosis with a slight trapezio-metacarpial subluxation. This is demanding hand surgery that should be performed by specialized surgeons only.
This arthroscopic thumb surgery is performed on an outpatient basis, under regional anaesthesia, with the thumb comfortably numbed.
First the arthritic thumb joint space is located at fluoroscopy and saline solution is injected into the trapezio-metacarpal joint with a needle.
Only two 2-mm incisions are required, one postero-external, the other postero-internal. The optical portal is postero-external; it is used to visualize the osteoarthritis, the osteophytes (bone spurs) and the inflammatory synovial membrane.
The first stage for this thumb surgery consists in performing gradual articular synovectomy to fully expose the osteoarthritic surfaces and marginal osteophytes. The initial instrumental and optical portals can be swapped to complete synovectomy.
The second stage of the surgical procedure consists in resecting the bone surfaces next to the metacarpal and trapezoid.
The arthroscopic portals are swapped so as to verify the main osteophytes have been completely resected and removed.
The arthroscopic incisions in the thumb are closed with Steri-strip; this hand surgery does not require any stitches.
Recovery after arthroscopic surgery for rhizarthrosis:
A removable thumb splint is necessary for 3 weeks, non-resistive movements with the thumb can resume after 3 weeks, complete recovery may take 2 to 3 months before forceful movements can resume without pain in the thumb.