Basal Thumb Joint Arthrosis
Arthrosis at the base of the thumb (rhizarthrosis) is the most common type of arthrosis affecting the hand, and the number of new cases in the population is estimated at 10%. This can increase to 25-50% in postmenopausal women. Both hormonal and genetic factors also play a role in the development of the disease, which explains why the disease is 10 times more common in women.
The special significance of arthrosis at the base of the thumb, known as rhizarthrosis, for hand surgeons and patients in particular stems from the thumb’s special anatomical characteristics. The thumb saddle joint, located between the first metacarpal bone and the trapezium, is where the thumb opposition movement takes place. This is the ability of the thumb to rotate and touch each fingertip of the same hand which, in turn, allows us to perform various grips – pinch grip, lateral (key) pinch, and power grip – all of which are immensely important in our daily lives. However, in the long term, thumb opposition places a great deal of strain on the articular cartilage in the saddle joint at the base of the thumb (trapeziometacarpal joint).
Diagnosis and Examination
During their appointment with their hand surgeon or orthopaedic specialist, patients tend to report pain at the base of their thumb when moving or using the saddle joint, for example, opening or locking doors, opening screw-top jars or bottles. Patients usually have swelling around the saddle joint, which female patients in particular find to be unattractive. Patients also report a significant loss of strength and a reduced range of movement in the thumb. The examining specialist will carry out compression and grind tests which, if positive for painful grating (crepitation), indicate cartilage damage.
Medical imaging, such as ultrasound, can be used to display the extent of the inflammation or synovialitis in the thumb saddle joint. As a matter of routine, a 2-plane x-ray of the saddle joint is taken. This enables the extent of the saddle joint arthrosis to be accurately determined and classified using the Eaton and Littler score of between 1 and 4. Depending on the severity of the disease, the treatment concept is then coordinated with the patient.
In the 1st and 2nd stages, conservative therapy can be attempted because damage to the cartilage or arthrosis is still at an early stage. This includes the fitting of a splint by a hand therapy specialist coupled with the use of non-steroidal anti-inflammatory drugs (NSAIDs). The local injection of corticoids/mixture of local anaesthetics can help relieve symptoms. Also, a suitable course of physiotherapy or special hand therapy can be helpful and lead to improved mobility and reduced thumb pain levels. Early-stage improvement has also been reported following the injection of hyaluronic acid. However, none of these conservative treatment approaches can cure rhizarthrosis.
If the symptoms and pain persist despite conservative therapy, an operation is the next option to be discussed. The pain usually forces the patient to visit a hand surgeon to request operative therapy with the aim of a return to pain-free daily life.
In the early stages of arthrosis, when the cartilage is not yet severely damaged, a range of treatment methods are used. Saddle joint arthroscopy can be used to remove detached fragments of cartilage (synovialectomy) and capsular shrinkage. Other available procedures include ligament reconstruction, corrective osteotomy, or the deactivation of the pain-transmitting nerve of the saddle joint (denervation).
Generally, however, patients visit a hand surgeon during the later 3rd and 4th stages when the arthrosis has led to extensive destruction of the cartilage. These patients have the option of being fitted with a joint prosthesis or undergoing resection arthroplasty of the thumb saddle joint. The implantation of a prosthesis, of which there are a wide range of models, allows for anatomical reconstruction following the partial or complete removal of the trapezium. However, it is not uncommon for complications to arise following implantation such as loosening of the prosthesis, dislocation, inflammation, foreign body reaction and overall unsatisfactory results.
Therefore, the various resection arthroplasty techniques with complete trapeziectomy (removal of the trapezium) continue to be the most commonly used methods to treat rhizarthrosis worldwide.
For more than 25 years, the preferred technique of the owner of the practice has been resection arthroplasty of the thumb saddle joint with complete removal of the trapezium (trapeziectomy) coupled with tendon suspensionplasty to stabilise the thumb by taking a graft from one of the thumb tendons (Lundborg resection arthroplasty). When performed by an experienced hand surgeon, 90% of patients are free of symptoms and regain full grip function, mobility, and strength.
The intervention is usually on an inpatient basis and is carried out using local (plexus) or general anaesthesia. The duration of the inpatient stay is usually 1-3 days.
At the end of the operation, a splint for the thumb and forearm is fitted. Thumb movement exercises can begin immediately after the operation. On the day of discharge, if the swelling of the thumb has already subsided, a hand therapist will customise a thermoplastic splint to stabilise the thumb. The pain experienced before the operation will gradually disappear. The suture material is removed at 12-14 days. The splint must be worn for a total of 5 weeks. This is followed by regular physiotherapy, preferably by a hand therapist. A return to pain-free full mobility and use of the thumb is usually possible after 3-5 months.