The objective of this study is to retrospectively evaluate the symptomatic effects of crystalline glucosamine sulfate (GS), prescribed for the actually approved indication of knee OA, in addition to conventional therapy, in comparison to the conventional therapy alone in patients with primary hand osteoarthritis (HOA).This is a 6-months retrospective comparative study including patients with concomitant knee and primary HOA, according to the ACR criteria. To be eligible the patients had to present clinical symptoms of hand OA for at least 3 months, defined as global hand pain score superior to 40 mm on a 0-100 Visual Analogue Scale (VAS) and a Functional Index for Hand Osteoarthritis (FIHOA) score of at least 6. Furthermore, the patients have had a radiographic evidence of HOA within the previous 6 months with a Kellgren-Lawrence score of II-III. The participants are stratified into two groups based on whether or not crystalline GS at the daily dose of 1500 mg was added to the conventional therapy for HOA, including exercise, acetaminophen and non steroidal anti-inflammatory drugs (NSAIDs) or cyclo-oxygenase (COX)-2 inhibitors. Primary outcome measures are the difference between the two groups in the change of VAS pain and in the FIHOA, from baseline after 6 months. Secondary outcomes were health assessment questionnaire (HAQ), medical outcomes study 36-item short form (SF-36) and symptomatic drugs consumption.

Inclusion Criteria:

• Mono or bilateral primary HOA and concomitant knee OA, according to the American College of Rheumatology (ACR) criteria
• Treatment for at least 6 consecutive months with crystalline GS at the daily dose of 1500 mg in addition to the conventional therapy or with usual care alone.
• HOA symptoms duration for at least 3 months defined as global hand pain score superior to 40 mm on a 0-100 VAS and a FIHOA score of at least 6.
• Radiographic evidence of HOA within the previous 6 months with a radiological score of II-III (using the Kellgren method).

Exclusion Criteria:

• Erosive Osteoarthritis of the hand
• Medical history of any inflammatory joint disease, septic arthritis, previous articular fracture of the concerned joints, monarticular post-traumatic OA of the finger, a history or the presence of any other rheumatic diseases that could cause secondary OA, such as hemochromatosis.
• Ongoing therapy with opioid analgesics and any kind of topical treatment
• Therapy with SYSADOAs other than GS, steroids by any route of administration and intra-articular injection of any joint with hyaluronic acid during the previous 6 months.
• Contraindications or special warnings for GS presented in the data sheet.

The participants were stratified into two groups based on whether or not (GS Group and Control Group) crystalline GS treatment, prescribed for the actually approved indication of knee OA, was added to the conventional therapy. This stratification was based on regrouping patients with similar clinical characteristics at baseline.