Other joint disorders

Acquired lateral deviation of the great toe (hallux valgus / bunion) where the treating clinician has not documented or cannot determine which foot is affected.

M20.11 identifies an acquired lateral deviation of the great toe at the first metatarsophalangeal joint, confirmed on the right foot, resulting from structural changes rather than a congenital condition.

Acquired lateral deviation of the left great toe at the first metatarsophalangeal joint, commonly presenting as a visible medial bony prominence (bunion) of the left foot.

Hallux rigidus of an unspecified foot — stiffness and limited dorsiflexion at the first metatarsophalangeal joint due to degenerative or acquired changes, coded when chart documentation does not specify right or left.

Degenerative arthritis of the right first metatarsophalangeal (MTP) joint causing progressive loss of dorsiflexion range of motion, classified as an acquired deformity of the toe under ICD-10-CM Chapter 13.

Degenerative arthritis of the left first metatarsophalangeal (MTP) joint causing progressive stiffness and loss of dorsiflexion, classified as an acquired deformity under ICD-10-CM chapter M20.

Acquired medial deviation of the great toe at the first metatarsophalangeal joint, laterality not documented or not specified by the treating provider.

Acquired medial deviation of the right great toe, where the hallux angles toward the midline of the body — the opposite direction from hallux valgus — resulting from post-surgical, traumatic, or inflammatory causes rather than congenital malformation.

Acquired medial deviation of the left great toe at the first metatarsophalangeal joint, resulting from a non-congenital cause such as prior surgery, trauma, or inflammatory arthritis.

Acquired hammer toe deformity affecting one or more lesser toes, with laterality not documented or unspecified in the medical record.

M20.41 identifies an acquired hammertoe deformity affecting one or more lesser toes of the right foot, distinguished from congenital deformities and from deformities of the great toe.

M20.42 identifies an acquired hammer toe deformity affecting one or more toes of the left foot, distinguished from congenital deformity by its post-birth onset.

M20.60 classifies an acquired deformity of one or more toes where neither the specific deformity type nor the affected foot (right or left) is documented.

M20.61 identifies an acquired deformity affecting one or more toes of the right foot where the specific deformity type is not documented or does not fit a more precise subcategory.

M20.62 captures an acquired deformity of one or more toes of the left foot where the specific deformity type is not documented or does not map to a more precise code in the M20 series.

M21.00 identifies an acquired valgus (outward angulation) deformity of a limb when the specific anatomical site is not documented or cannot be determined from the record.

Acquired varus (inward angulation) deformity of a limb with no specific anatomical site documented in the medical record.

M21.20 identifies an acquired flexion deformity without documentation of a specific anatomical site. Use this code only when the affected joint or limb region is genuinely unspecified in the clinical record.

Acquired flat foot (pes planus) affecting an unspecified foot — meaning laterality was not documented or cannot be determined from the record.

Acquired collapse of the medial longitudinal arch of the right foot, coded specifically when pes planus developed after birth due to injury, tendon dysfunction, arthritis, or other acquired cause — not a structural anomaly present at birth.

Acquired collapse of the medial longitudinal arch of the left foot, documented as developing after birth due to an identifiable cause such as posterior tibial tendon dysfunction, trauma, or arthritis — not a congenital structural variant.

Acquired discrepancy in length between paired limbs (upper or lower) when the specific anatomical site cannot be or has not been documented.

M21.80 captures acquired deformities of a limb that are neither congenital nor classifiable to a more specific M21 subcategory, where the affected limb is not documented.

An acquired (non-congenital) deformity affecting a limb where neither the specific limb nor the type of deformity is documented or identifiable from the clinical record.

Chronic, non-traumatic condition in which the patella repeatedly displaces from the trochlear groove, coded here when the treating clinician has not specified whether the right or left knee is affected.

Recurrent dislocation of the patella at the right knee — a non-traumatic, pattern-based diagnosis indicating the kneecap has dislocated multiple times, reflecting underlying patellar instability rather than a single acute event.

M22.02 identifies recurrent dislocation of the patella in the left knee — a chronic instability pattern in which the kneecap repeatedly displaces from the trochlear groove, distinct from a single traumatic event.

Recurrent subluxation of the patella with laterality not documented or specified in the clinical record.

Chronic, repetitive incomplete dislocation of the right patella in which the kneecap repeatedly slides partially out of the trochlear groove without fully dislocating.

Recurrent subluxation of the left patella — repeated episodes of incomplete kneecap displacement from the trochlear groove, left side only, not caused by a single acute traumatic event.

Softening or breakdown of the cartilage on the underside of the kneecap, coded without specification of which knee is affected.

Softening and surface breakdown of the cartilage on the posterior face of the right patella, classified under disorders of the patella in the musculoskeletal chapter.

Degenerative softening and breakdown of the articular cartilage on the underside of the left kneecap (patella), classified under patellar disorders in ICD-10-CM Chapter 13.

M22.90 classifies a patellar disorder that cannot be assigned to a more specific subcategory and for which laterality (right vs. left) is also undocumented.

M22.91 captures an unspecified disorder of the patella localized to the right knee — used when a specific patellar condition cannot be identified or documented with greater precision.

M22.92 identifies an unspecified disorder of the patella (kneecap) localized to the left knee, used when a specific patellar condition cannot be further classified.

M23.40 identifies a loose body within the knee joint when the operative or affected side is not documented or cannot be determined.

M23.41 identifies an intra-articular loose body — a free fragment of bone, cartilage, or both — specifically within the right knee joint.

M23.42 identifies a loose body — a detached fragment of bone, cartilage, or other intra-articular material — present within the left knee joint.

Chronic instability of the knee, reported when laterality (right or left) is not documented in the medical record.

Chronic instability of the right knee due to ligamentous insufficiency, representing a persistent, non-acute condition of the right knee joint that has not resolved after the initial injury period.

Chronic instability of the left knee due to ligamentous laxity or insufficiency, representing a persistent, non-acute condition affecting joint integrity on the left side.

M23.90 classifies internal derangement of the knee when neither the specific type of derangement nor the laterality (right or left) is documented in the medical record.

M23.91 identifies an internal derangement of the right knee where the specific structure involved — meniscus, ligament, loose body, or other intra-articular component — has not been further defined in the clinical documentation.

M23.92 classifies unspecified internal derangement of the left knee — used when the clinical picture points to a structural knee joint problem on the left side but the specific pathology (meniscal tear, ligament laxity, loose body, etc.) cannot be identified from the documentation.

Loose body in an unspecified joint — fragments of bone and/or cartilage that float freely within a joint space, with the affected joint not documented or identifiable from the record.

M24.08 identifies the presence of a loose body (a detached fragment of bone, cartilage, or other tissue) within a joint at a site not captured by any other specific M24.0x code in the classification — meaning a joint other than the shoulder, elbow, wrist, hand, hip, knee, ankle, or toe joints.

M24.10 classifies articular cartilage disorders that fall outside other specifically defined cartilage conditions — such as chondrocalcinosis or internal derangement of the knee — when the affected joint site is not documented.

M24.19 captures articular cartilage disorders at joints that don't have a dedicated site-specific code within the M24.1 subcategory — a true 'other specified site' catch-all for non-standard anatomical locations.

M24.20 captures a ligament disorder — including instability from old ligament injury or ligamentous laxity NOS — when no anatomical site is documented in the record.

M24.28 classifies a non-traumatic disorder of one or more spinal ligaments that does not fall under a more specific vertebral instability or derangement code.

Chronic or non-traumatic ligamentous pathology occurring at a joint site not captured by any other specific M24.2x subcategory — a true residual bucket for documented ligament disorders that lack a dedicated laterality-specific code.

Pathological dislocation of a joint that occurs due to disease or pathological process rather than acute trauma, reported when the specific joint is not documented or does not have a more precise code available.

Pathological dislocation of a joint not covered by more specific M24.3 subcategories — used when the affected joint falls outside the spine, shoulder, elbow, wrist, finger, hip, knee, ankle, foot, or toe groupings already enumerated in M24.3.

Recurrent dislocation of a joint where the specific joint has not been documented or identified in the medical record.

Recurrent dislocation or subluxation of a joint that does not map to any of the more specifically enumerated joint sites in the M24.4x subcategory — a true catch-all for joints such as the sternoclavicular, acromioclavicular, patellofemoral (when not captured elsewhere), or small joints of the hand and foot that lack a dedicated laterality code under M24.4.

Joint contracture at an unspecified anatomical site — used when the affected joint is not documented in the medical record.

M24.59 captures joint contracture at a site that doesn't map to any of the eight named-site subcategories in the M24.5x series — use it when the affected joint is documented but falls outside shoulder, elbow, wrist, hand, hip, knee, or ankle/foot.

M24.60 identifies ankylosis — abnormal fusion or immobility of a joint — when the specific joint affected is not documented or cannot be determined from the record.

Ankylosis of a joint not captured by any other site-specific code in the M24.6x series — meaning fibrous or osseous fusion at a location outside shoulder, elbow, wrist, hand, hip, knee, ankle, or foot.