M66.239 Spontaneous rupture of extensor tendons, unspecified forearm

Billable ICD-10-CM code, FY2026.

Applies from M66 Spontaneous rupture of synovium and tendon

Includes

• rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength

Excludes2 (not included here)

• rotator cuff syndrome (M75.1-)
• rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region

MS-DRG index

Defines the logic of DRG(s) 557-558 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 727.63 Nontraumatic rupture of extensor tendons of hand and wrist (approximate)

Code annotations containing back-references to M66.239

Back-references to M66

• Type 2 Excludes: M62.1 Other rupture of muscle (nontraumatic) ("rupture of tendon (M66.-)")

Nearby codes

• M66.222 Spontaneous rupture of extensor tendons, left upper arm
• M66.229 Spontaneous rupture of extensor tendons, unspecified upper arm
• M66.23 Spontaneous rupture of extensor tendons, forearm
• M66.231 Spontaneous rupture of extensor tendons, right forearm
• M66.232 Spontaneous rupture of extensor tendons, left forearm
• M66.239 Spontaneous rupture of extensor tendons, unspecified forearm (this code)
• M66.24 Spontaneous rupture of extensor tendons, hand
• M66.241 Spontaneous rupture of extensor tendons, right hand
• M66.242 Spontaneous rupture of extensor tendons, left hand
• M66.249 Spontaneous rupture of extensor tendons, unspecified hand
• M66.25 Spontaneous rupture of extensor tendons, thigh