M18: ICD10 Code for Osteoarthritis of first carpometacarpal joint

M18 refers to Osteoarthritis of first carpometacarpal joint, a form of degenerative joint disease marked by cartilage breakdown, bone remodeling, and eventual joint stiffness and pain. These conditions are the leading cause of joint disability in adults and older populations.

Symptoms

• Joint pain – Especially with movement or weight-bearing (hips, knees, hands)
• Joint stiffness – Typically after periods of inactivity, improving with use
• Swelling and tenderness – Common in affected joints
• Reduced range of motion – Seen in advanced osteoarthritis (M16, M17, M18)
• Bony enlargements – Nodes at finger joints or visible deformities

Diagnosis

Diagnosis of Osteoarthritis of first carpometacarpal joint is based on clinical examination, history, and radiologic findings (joint space narrowing, osteophyte formation, subchondral sclerosis). MRI may detect early cartilage changes. Laboratory tests are mainly used to exclude inflammatory arthritis.

ICD10 Code Usage

ICD10 code M18 is used by orthopedic surgeons, rheumatologists, primary care physicians, physical therapists, and rehabilitation teams to guide management, insurance billing, and surgical planning (e.g., joint replacement).

Related Codes

• M15 – Polyosteoarthritis
• M16 – Osteoarthritis of hip
• M17 – Osteoarthritis of knee
• M19 – Other and unspecified osteoarthritis

FAQs

Q1: What is ICD10 code M18?
A: It refers to Osteoarthritis of first carpometacarpal joint, a chronic degenerative disorder causing joint pain, stiffness, and functional limitation due to cartilage loss.

Q2: How does polyosteoarthritis (M15) differ from other codes?
A: M15 involves multiple joints throughout the body, while M16–M18 refer to specific joints like hip, knee, or thumb base.

Q3: Is osteoarthritis only age-related?
A: While age is a major risk factor, injuries, obesity, genetics, and joint overuse also contribute.

Q4: How is osteoarthritis treated?
A: Treatments include weight management, physical therapy, NSAIDs, intra-articular injections, and surgical interventions like joint replacement.

Q5: Who typically manages osteoarthritis?
A: Orthopedic surgeons, rheumatologists, physiotherapists, and primary care providers collaboratively manage osteoarthritis based on severity.

Conclusion

ICD10 code M18 provides essential classification for Osteoarthritis of first carpometacarpal joint, enabling appropriate treatment planning, surgical decision-making, and disability assessment in patients with degenerative joint disease.