The thumb of the human hand , much more advantageous than that of the primate, is completely opposable to the other four fingers and allows to make a precision clamp, so it can manipulate objects of different sizes.
This evolutionary advantage means that there is a daily use of the hand and, consequently, a greater predisposition to suffer a joint degeneration of the trapezium-metacarpal joint known as osteoarthritis of the base of the thumb or rizarthrosis .
The aforementioned rizarthrosis affects more prevalently the postmenopausal woman, being the relation with the male of 1/10. 30% of them are bilateral. Among the causes to produce osteoarthritis at this level, the most frequent are: joint overuse, genetic predisposition, hormonal factors and hypermobility.
Only one third of the rhizarthrosis are clinically significant and the patient requires medical assistance, medication and, occasionally, incapacity for work.. When it is advanced it can constitute an important limitation of the functional capacity of the hand , as well as producing pain , instability , deformation and loss of mobility .
The treatment is initially conservative, based on analgesics and chondroprotectors , in addition to occupational therapy for better use of the hand, hyaluronic acid infiltrations (initial stages) and the use of corrective orthoses.
When the usual treatment fails, each case must be individualized according to the age and degree of osteoarthritis. There is a wide range of possibilities, from minimally invasive surgeries such as trapezium-metacarpal arthroscopy to arthrodesis in manual strength workers, trapezius-metacarpal arthroplasty and interpositional joint replacement arthroplasty.. It should be noted that a part of the hand so specialized requires a very demanding treatment, always seeking the least invasive and aggressive surgical techniques, with which good clinical results are obtained.