Although a common problem, hand osteoarthritis (HOA) is less studied than knee and hip. In the age group of 71-100 years, the prevalence of symptomatic HOA reaches 26% of women and 13% of men. These patients lose hand strength and have difficulty with day-to-day manual activities. The main joints involved are the proximal and distal interphalangeals and the carpometacarpal joint of the thumb. In the educational Project PARQVE, the prevalence of HOA was 23.7% at inclusion in the program, and 47.4% after one year, with loss of grip strength. There is controversy over the effect of viscosupplementation in the treatment of rhizarthritis when considering pain. However, strength is a very important function parameter that must be evaluated for function and quality of life maintenance. Concerned about the importance of maintaining strength and function in our program (PARQVE), we have added specific exercises tom improve hand strength and range of motion. Trying to optimize the treatment and confronting questions about the effect of the joint wash, called placebo in the comparative studies with corticosteroid and/or hyaluronic acid injection, we did a work where all the patients will be washed with physiological saline solution but a group, after emptying, will receive 1mL of hyaluronic acid with mannitol.

PURPOSE: To compare isolated lavage with lavage followed by injection of hyaluronic acid with mannitol into carpometacarpal osteoarthritis joint of the thumb.

METHODS: Forty joints of patients with multiple osteoarthritis (rhizoarthritis, including) and comorbidities (two or more of: overweight or obesity, hyperglycemia, dyslipidemia, hyperuricemia, hypertension) will be allocated into two groups: Lavage (LS) and Lavage and Injection Hilauronic acid (LO). Both groups will undergo joint lavage with saline solution. The LO group will receive the 20 mg / mL hilauronic acid injection with 5mg mannitol. Both groups will be guided in the clinical treatment of osteoarthritis and metabolic syndrome and will be given daily exercises for the hands. They will be evaluated with the quick DASH questionnaire, Sollerman Test and by measuring the palmar, lateral and pulp-pulp grip strength, in addition to measuring the ROM and VAS pain moments immediately prior to the procedure, one, three and six months after the articular procedure.

Patients with multiple osteoarthritis (including carpometacarpal joint of the thumb, stages I to III - Eaton et al.) in treatment at the Institute of Orthopedics and Traumatology fo the Clinics Hospital - University of São Paulo (IOT-HC-FMUSP) will be invited to participate in this study.

All patients are obliged to participate in a two-day education course on OA. During the program they are instructed about OA, metabolic syndrome, comorbidities and importance of diet, and daily exercise (including specific exercises for the hand).

After inclusion, 40 joints will be randomized in one of two treatment options, i.e., Lavage with saline solution and final injection of 1mL of saline solution, or lavage with saline solution followed by injection of 10mg of hyaluronic acid with mannitol (5mg).

After the procedure patients will receive naproxen 500mg twice daily for 5 days.

Patients will be instructed to exercise at least 180 minutes/week and if possible daily exercise for the hand (5 to 10 minutes daily).

Patients will be instructed to write down when and what they exercised as well as their daily medication intake (for co-morbidities and pain).

All patients will be submitted to pain (VAS), range of motion (ROM), Quick DASH, Sollermand Test and functional (palmar grip strength and lateral and pulp-pulp pinch strength) evaluations immediately prior to the procedure and after 1, 3 and 6 months of each joint.

As the assessments of pain, range of motion and strength will be compared with measurements of the same limb at inclusion, each hand involved of the patient will be considered as a case.

The "n" was calculated to obtain a statistical power of 80% and a level of significance of 5%. To do this, we considered the mean and standard deviation of the pulp-pulp pinch (our primary outcome) found in previous study of the prevalence of hand OA in individuals with knee osteoarthritis submitted to our educational program. A sample size was used to detect a variation of 1 point on the two-tailed pulp-pulp pinches. The sample size calculated by group was 16. Considering also possible faults and abandon of about 20% of the patients, the value of 20 patients per group was obtained.

Inclusion Criteria:

• Men and women diagnosed with multiple arthritis (including CMC OA of the thumb) with comorbidities (metabolic syndrome, i.e., OA and overweight / obesity, and/or hyperglycemia, and/or dyslipidemia, and/or hyperuricemia, and/or hypertension).
• CMC OA joint of the thumb stages I to III as classified by Eaton et al. (4)

Exclusion Criteria:

• Missing classes or functional evaluations
• Not performing the exercises as instructed