Classification of osteoarthritis

Currently, there is no unified approach to the terminology and classification of osteoarthrosis in global clinical practice. When writing this chapter, the authors tried to unify the available information and justify the use in rheumatological practice (as well as in the practice of doctors of related specialties) of the terminology and classification of osteoarthrosis proposed by the Association of Rheumatologists of Ukraine, in the development of which the authors of the book took part.

Confusion in the terminology of osteoarthritis has existed for a long time. Clinicians who dealt with the problem of joint diseases, called this pathology differently. As an example, a far from complete list of names of osteoarthritis is given.

• Deforming arthritis (Virchow)
• Degenerative arthritis
• Hypertrophic arthritis (Goldthwaite)
• Senile hypertrophic arthritis (Hench)
• Dry arthritis (Hunter)
• Senile arthritis (Hench)
• Deforming arthropathy (Barcelo)
• Degenerative arthropathy (Abrams)
• Multiple degenerative arthropathy
• Arthrosclerosis (Lucherini)
• Deforming arthrosis
• Dry arthrosynovitis
• Dry arthrosis
• Senile arthrosis
• Degenerative hypertrophic chondroosteoarthritis (Weil MP)
• Degenerative joint disease (Lunedei; Bauer and Bennett)
• OcTeoapTpHT(A.Garrod)
• Chronic degenerative osteoarthritis (Bezancon and Weil)
• Hypertrophic degenerative osteoarthritis (Bezancon and Weil)
• Osteoarthritis
• Progressive dry polyarthritis (Weissenbach and Francon)
• Ambulatory rheumatism
• Chronic articular rheumatism (Cruveilhier)
• Incomplete chronic articular rheumatism (Charcot)
• Chronic degenerative rheumatism (Nichols and Richardson)
• Chronic hypertrophic rheumatism (Nichols and Richardson)
• Chronic ossalgic rheumatism
• Chronic osteophytic rheumatism
• Incomplete chronic rheumatism
• Simple chronic rheumatism (Besnier)
• Deforming rheumatism (Virchow)
• Degenerative rheumatism
• Heberden's Rheumatism (Charcot)
• Synovial rheumatism

Some of the above terms reflect objective clinical and pathogenetic significance, for example, “senile hypertrophic arthritis” and, most importantly, contrast osteoarthritis with other joint diseases.

Currently, the most common term in the world is "osteoarthritis", in the CIS countries, as well as in some European countries (Germany, France) we use the term "osteoarthrosis". In light of current knowledge about the pathogenesis of osteoarthrosis, the first term reflects the essence of the disease to a greater extent. At the same time, we do not see the need to change the terminology generally accepted in our country and recommend using the term "osteoarthrosis".

In medical documentation (medical history, outpatient card, referral for consultation, etc.) you can still find the diagnosis of "deforming (osteo)arthrosis" or "metabolic-dystrophic polyarthritis". Both terms are obsolete and are not included in ICD-10, they should not be used when formulating a clinical diagnosis. In the first case, it is advisable to avoid the word "deforming", and in the second - to use the term "polyosteoarthrosis".

There are many unresolved issues in the classification of osteoarthrosis. Let's consider the main ones.

On the issue of spinal osteochondrosis. In most classifications (for example, in the ACR classification below), osteochondrosis is included in the spinal osteoarthrosis group, however, by definition, pathogenesis and clinical picture, spinal osteoarthrosis and spinal osteochondrosis are completely different diseases:

• by definition, osteoarthrosis is a disease of the synovial joints (diarthroses), in relation to the spine - osteoarthrosis of the so-called apophyseal joints (joints between the upper articular processes of the underlying and lower articular processes of the overlying vertebrae), osteochondrosis is a degenerative lesion of the cartilaginous joints (amphiarthroses), i.e. intervertebral discs. Osteoarthrosis and osteochondrosis are combined into a group of degenerative joint diseases;
• Osteoarthritis of the spine is characterized by a dissociation between the radiological and clinical picture of the disease - even significant progression of morphological changes in the apophyseal joints, including the formation of large osteophytes, as a rule, does not manifest clinically; with osteochondrosis, on the contrary, there is a clear connection between the destruction of the intervertebral discs, determined radiologically, and the clinical manifestation (radicular syndrome).

Of course, osteoarthritis of the spine and osteochondrosis are diseases that often accompany each other, since changes in the synovial joints sharply increase the load on the discs, which leads to osteochondrosis, and vice versa. However, the American College of Rheumatology, the Italian Society of Rheumatology, etc. (see below) have combined these two different diseases into one group.

All of the above is reflected in ICD-10. According to this classification, osteoarthrosis belongs to the rubric ARTHROSIS M15-M 19, OA of the spine - to the rubric M47, and osteochondrosis of the spine - to the rubric M40-M43 DEFORMING DORSOPATHIES.

On the issue of the nodular form of polyosteoarthrosis A. In the classifications of the CIS countries (for example, in the classification of V.A. Nasonova and M.G. Astapenko, 1989), two clinical (italics ours) forms of polyosteoarthrosis (POA) are distinguished - nodular and nodular-free. According to the ACR classification (1986), nodular and nodular-free variants are noted in osteoarthrosis of the joints of the hands: the presence of Bouchard's and Heberden's nodes is classified as nodular osteoarthrosis of the hands, and the presence of "erosions" (these are not classic RA erosions, or rather, an intermittent cortical line on radiographs of the hands) - as nodular-free or erosive osteoarthrosis of the hands. Therefore, the question of the advisability of extending the gradation of hand osteoarthrosis to the entire POA (or generalized osteoarthrosis, according to English-speaking authors) remains debatable.

On the issue of polyosteoarthrosis (generalized osteoarthrosis). Domestic classifications and monographs do not indicate which osteoarthrosis should be considered polyosteoarthrosis. According to JH Kellegren, the author of the term "generalized osteoarthrosis", who first described this variant, generalized osteoarthrosis means "... the presence of radiographic signs of osteoarthrosis in 6 or more groups of joints, usually in the metacarpophalangeal joints of the first finger and proximal interphalangeal joints of the second-fifth fingers of the hand (Heberden's nodes), apophyseal joints of the spine, knee, hip joints, as well as in the tarsometatarsal joints of the first toe." ACR (1986) reduced the number of joint groups for establishing the diagnosis of POA to three: "Generalized osteoarthrosis is a lesion of three or more groups (not joints, as rheumatologists often believe) of joints.

On the issue of osteoarthrosis of the knee joint. At present, the domestic literature does not indicate the division of the knee joint into regions or sections (in foreign literature - compartment) - patellofemoral (patella-femoral) and lateral and medial tibiofemoral (tibiofemoral). At the same time, all foreign manuals indicate the importance of such a division. Thus, according to PA Dieppe (1995), the most common are isolated osteoarthrosis in the medial tibiofemoral section of the joint and combined lesions of the medial tibiofemoral and patellofemoral sections; osteophytosis is more often found in the lateral tibiofemoral section, and destruction of the articular cartilage is usually more pronounced in the medial, which leads to the development of varus deformity. According to T.E. McAlindon et al. (1993) found that the medial tibiofemoral joint is affected in 75% of cases, the lateral joint in 26%, and the patellofemoral joint in 48%. ACR distinguishes gonarthrosis of the medial tibiofemoral joint, lateral tibiofemoral joint, and patellofemoral joint.

Classification of osteoarthritis according to ICD-10

Arthrosis (Ml5-M 19)

Note: In this block, the term osteoarthritis is used as a synonym for arthrosis or osteoarthrosis. The term primary is used in its usual clinical meaning.

Excludes: osteoarthritis of spine (M47.-)

M15 Polyarthrosis

Includes: arthrosis of more than one joint

Excluded: bilateral involvement of the same joints (M l6-M19)

M15.0 Primary generalized (osteo)arthrosis

M15.1 Heberden's nodes (with arthropathy)

M15.2 Bouchard's nodes (with arthropathy)

M15.3 Secondary multiple arthrosis

Posttraumatic polyarthrosis

M15.4 Erosive (osteo)arthrosis

M15.8 Other polyarthrosis

M15.9 Polyarthrosis, unspecified

Generalized osteoarthritis NOS

M16 Coxarthrosis [arthrosis of the hip joint]

M16.0 Primary coxarthrosis bilateral

M16.1 Other primary coxarthrosis

Primary coxarthrosis:

• BDU
• unilateral

Ml6.2 Coxarthrosis due to dysplasia, bilateral

M16.3 Other dysplastic coxarthrosis

Dysplastic coxarthrosis:

• BDU
• unilateral

M16.4 Posttraumatic coxarthrosis bilateral

M16.5 Other posttraumatic coxarthrosis

Posttraumatic coxarthrosis:

• BDU
• unilateral

M16.6 Other secondary coxarthrosis, bilateral

M16.7 Other secondary coxarthrosis

Secondary coxarthrosis:

• BDU
• unilateral

M16.9 Coxarthrosis, unspecified

M17 Gonarthrosis [arthrosis of the knee joint]

M17.0 Primary gonarthrosis bilateral

M17.1 Other primary gonarthrosis

Primary gonarthrosis:

• BDU
• unilateral

M17.2 Posttraumatic gonarthrosis bilateral

M17.3 Other posttraumatic gonarthrosis

Posttraumatic gonarthrosis:

• BDU
• unilateral

M17.4 Other secondary gonarthrosis, bilateral

M17.5 Other secondary gonarthrosis

Secondary gonarthrosis:

• BDU
• unilateral

M17.9 Gonarthrosis, unspecified

M18 Arthrosis of the first carpometacarpal joint

M18.0 Primary arthrosis of the first carpometacarpal joint, bilateral

M18.1 Other primary arthroses of the first carpometacarpal joint

Primary arthrosis of the first carpometacarpal joint:

• BDU
• unilateral

M18.2 Posttraumatic arthrosis of the first carpometacarpal joint, bilateral

M18.3 Other posttraumatic arthroses of the first carpometacarpal joint

Posttraumatic arthrosis of the first carpometacarpal joint:

• BDU
• unilateral

M18.4 Other secondary arthroses of first carpometacarpal joint, bilateral

M18.5 Other secondary arthroses of the first carpometacarpal joint

Secondary arthrosis of the first carpometacarpal joint:

• BDU
• unilateral

M18.9 Arthrosis of first carpometacarpal joint, unspecified

M19 Other arthroses

Excluded:

• arthrosis of the spine (M 47.-)
• rigid big toe (M20.2)
• polyarthrosis (M15.-)

M19.0 Primary arthrosis of other joints

Primary arthrosis NCD

M19.1 Posttraumatic arthrosis of other joints

Posttraumatic arthrosis NCD

M 19.2 Secondary arthrosis of other joints

Secondary arthrosis NCD

M19.8 Other specified arthrosis

M19.9 Arthrosis, unspecified

M47 Arthrosis of the spine

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American College of Rheumatology (ACR) Classification of Osteoarthritis

I. Idiopathic (primary)

A. Localized

1. Brushes:

• Heberden's and Bouchard's nodes (nodular form)
• erosive osteoarthritis of the interphalangeal joints (non-nodular form)
• osteoarthritis of the scaphocarpal joint
• osteoarthritis of the scaphotrapezius joint

2. Feet:

• hallux valgus
• hallux rigidus
• flexion/extension contracture of fingers
• osteoarthritis of the calcaneonavicular joint

3. Knee joint:

• osteoarthritis of the medial tibiofemoral joint
• osteoarthritis of the lateral tibiofemoral joint
• osteoarthritis of the patellofemoral joint

4. Hip joint:

• eccentric (upper)
• concentric (axial, medial)
• diffuse (coxae senilis)

5. Spine (mainly cervical and lumbar regions):

• apophyseal joints
• intervertebral discs
• spondylosis (osteophytes)
• ligaments (hyperostosis, Forestier's disease, diffuse idiopathic hyperostosis of the skeleton)

6. Other localizations:

• shoulder joint
• acromioclavicular joint
• tibiocalcaneal joint
• sacroiliac joints
• temporomandibular joints

B. Generalized (includes three or more of the joint groups described above)

• Small joints and spinal joints
• Large joints and joints of the spine
• Small and large joints and joints of the spine

II. Secondary

A. Post-traumatic

1. Spicy
2. Chronic (associated with certain professions, sports)

B. Congenital diseases and developmental pathology

1. Localized:

A) diseases of the hip joint:

• Legg-Calve-Perthes disease
• congenital hip dysplasia
• slipped epiphysis of the femur

B) local and mechanical factors:

• shortening of the lower limb
• valgus/varus deformity
• hypermobility syndrome
• scoliosis

2. Generalized:

A) bone dysplasia

B) metabolic diseases:

• hemochromatosis
• ochronosis (alkaptonuria)
• Wilson-Konovalov disease
• Gaucher disease

B. Calcium deposition diseases

1. Calcium Pyrophosphate Crystal Deposition Disease
2. Calcium hydroxyapatite crystal deposition disease

G. Other diseases of bones and joints

1. Localized

• Fractures
• Avascular necrosis
• Infections
• Gouty arthritis

2. Diffuse

• Rheumatoid arthritis
• Paget's disease
• Osteopetrosis
• Osteochondritis

D. Others

• Acromegaly
• Hyperparathyroidism
• Diabetes mellitus
• Obesity
• Hypothyroidism
• Charcot arthropathy
• Other:
  • Frostbite
  • Caisson disease
  • Kashin-Beck disease
  • Hemoglobinopathies

Benefits of ACR classification:

• Osteoarthritis of the hands is divided into nodular and non-nodular (erosive) variants
• Osteoarthritis of the knee joints is divided into three anatomical zones - osteoarthritis of the tibiofemoral (medial and lateral) joint and osteoarthritis of the patellofemoral joint
• secondary osteoarthrosis is described in detail (however, this point can also be attributed to the shortcomings of the classification, since the expanded second part makes it too voluminous, complicating its perception and use in formulating a diagnosis).

Disadvantages of ACR classification:

• Osteoarthritis of the spine includes not only degeneration of intervertebral discs, but also calcification of ligaments
• Osteoarthritis includes damage to the sacroiliac joints, which do not belong to the synovial group and therefore cannot be affected by osteoarthritis.

[ 5 ], [ 6 ], [ 7 ], [ 8 ]

Classification of osteoarthritis of the Italian Society of Rheumatology (SIR)

I. Primary osteoarthritis

A. Diffuse

B. Local:

• Heberden's and Bouchard's nodes
• osteoarthritis of the scaphocarpal joint
• erosive osteoarthritis of the interphalangeal joints of the hands, etc.

II. Secondary osteoarthritis

1. Dysplasia and dysmorphism
2. Traumatic
3. Functional overload

A) obesity, scoliosis, shortened lower limb, etc.

B) associated with certain professions and sports

1. Arthritis
2. Congenital diseases of connective tissue
   • Marfan syndrome
   • Morquio syndrome
   • mucopolysaccharidosis

6. Simple chondropathy

• articular chondromatosis
• osteochondritis dissecans

7. Endocrine-metabolic chondropathy:

• diabetes mellitus
• chondrocalcinosis
• ochronosis, etc.

8. Osteopathy

• Paget's disease
• aseptic necrosis

III. Degeneration of intervertebral discs (dyscarthrosis)

IV. Dysmetabolic hyperostotic arthropathy

V. Acromegalic arthropathy

VI. Chondromalacia of the patella

Disadvantages of SIR classification:

• no indication of the localization of lesions
• intervertebral disc degeneration is not osteoarthritis
• points IV-VI refer to secondary osteoarthritis (point II)

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Clinical classification of osteoarthritis

I. Pathogenetic variants

1. Primary (idiopathic)
2. Secondary (caused by dysplasia, trauma, static disorders, joint hypermobility, arthritis, etc.)

II. Clinical forms

1. Polyosteoarthrosis: nodular, non-nodular
2. Oligosteoarthrosis
3. Monoarthrosis
4. In combination with osteoarthritis of the spine, spondyloarthrosis

III. Preferential localization

1. Interphalangeal joints (Heberden's nodes, Bouchard's nodes)

1. Hip joints (coxarthrosis)
2. Knee joints (gonarthrosis)
3. Other joints

IV. Radiographic stage (according to Kellgren JH and Lawrence JS): I, II, III, IV

V. Synovitis

1. Available
2. Absent

VI. Functional capacity of the patient

1. Working capacity is temporarily limited (FN*-1)
2. Working capacity lost (FN-2)
3. Requires outside care (FN-3).

* FN - functional insufficiency.

The diagnosis of osteoarthritis should include an indication of which joint is affected, the area of greatest damage (for example, the medial or lateral part of the knee joint), the presence of synovitis and the degree of dysfunction of the joint, and, in the case of damage to the knee and hip joints, the radiographic stage.

This classification is most suitable for use in formulating a diagnosis. However, in our opinion, it has some shortcomings, in particular, the division of PAO into nodular and non-nodular forms (as indicated above), there is no division of osteoarthrosis of the knee joint into sections, for osteoarthrosis of the hands only the nodular variant is given.

Taking into account the advantages and disadvantages of the above classifications, the classification of osteoarthrosis of the Association of Rheumatologists of Ukraine (ARU) was created, which we recommend as a working one. ARU (2000)

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Working classification of osteoarthritis

Pathogenetic variants

I. Idiopathic (primary)

II. Secondary

Clinical forms

1. Monoosteoarthrosis (damage to one joint)
2. Oligosteoarthrosis (damage to two or more joints, but not more than two groups of joints)
3. Polyosteoarthrosis (damage to three or more groups of joints)

Localization

1. Knee joint:

• osteoarthritis of the medial tibiofemoral region
• osteoarthritis of the lateral tibiofemoral region
• patellofemoral osteoarthritis

2. Hip joint

• eccentric (upper)
• concentric (axial, medial)
• diffuse (coxae senilis)

3. Brushes:

• Heberden's and Bouchard's nodes (nodular form)
• erosive osteoarthritis of the interphalangeal joints (non-nodular form)
• osteoarthritis of the carpometacarpal joint of the first finger of the hand
• osteoarthritis of other joints of the hands

4. Spine

• apophyseal joints

5. Feet:

• hallux valgus
• hallux rigidus
• osteoarthritis of other joints of the foot

6. Other localizations

Synovitis

1. With synovitis
2. Without synovitis

Radiographic stage (PC)* (no Kellgren JH and Lawrence JS)

0, I, II, III, IV Functional capacity of the patient

1. Working capacity is temporarily limited (FN-1)
2. Working capacity lost (FN-2)
3. Needs outside care (FN-3)

*For OA of the knee, hip and hand joints, PC must be indicated

Examples of formulation of diagnoses

1. Secondary monoosteoarthrosis of the left knee joint (medial tibiofemoral and patellofemoral sections) with synovitis. RS-P.FN-1.
2. Primary oligoosteoarthrosis with damage to the left hip joint (concentric), PC - III, both knee joints (lateral tibiofemoral sections), PC - II. Synovitis of the right knee joint. FN-1.
3. Primary polyosteoarthrosis with damage to the joints of the hands (Heberden's nodes), PC - III, left knee joint (lateral tibiofemoral section), PC - III and right hip joint (diffuse), PC - IV. Synovitis of the left knee joint and distal interphalangeal joints. FN-1.
4. Primary polyosteoarthrosis with damage to the proximal and distal interphalangeal joints of the hands (erosive form), PC - III, carpometacarpal joint of the 1st finger of the left hand with synovitis, metatarsophalangeal joint of the 1st toe of the right foot (hallux valgus) with synovitis, right hip joint (concentric), PC - IV and cervical spine. FN-2.

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Classification criteria for osteoarthritis

Classification criteria are a kind of diagnostic search algorithm. However, when diagnosing a disease, including OA, one should not rely only on classification criteria. It is important to remember that their main area of use is not routine clinical practice, but clinical research - compliance with classification criteria is one of the grounds for including a patient in the study.

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Arthrosis of the hands (according to Altaian RD et al., 1990)

1. Pain, stiffness, or rigidity in the hands, usually during the day, during the past month and
2. Dense thickening of two or more joints* and
3. Less than three swollen metacarpophalangeal joints, or
   • hard thickening of two or more distal interphalangeal joints or
   • incorrect position of one or more joints*.

* Distal interphalangeal joints of the II and III fingers; proximal interphalangeal joints of the II and III fingers; carpometacarpal joints of both hands. Sensitivity is 93%, specificity is 97%.

[ 26 ], [ 27 ]

Coxarthrosis (according to Altman RD et al., 1991)

Clinical symptoms

1. Hip pain
2. internal rotation less than 15 degrees
3. ESR less than 45 mm/h (with normal ESR - hip flexion less than 115 degrees)
4. internal rotation less than 15 degrees
5. pain with internal rotation
6. morning stiffness less than 60 min
7. age over 50 years

Sensitivity is 86%, specificity is 75%.

Clinical and radiological symptoms

Hip pain and at least 2 of the following 3 signs:

• ESR less than 20 mm/h,
• radiologically - osteophytes (head of the femur or acetabulum)
• radiologically - narrowing of the joint space (above, laterally and/or medially).

Sensitivity - 89%, specificity - 91%.

[ 28 ], [ 29 ], [ 30 ]

Gonarthrosis (according to Altman RD et al., 1986)

1. Knee joint pain
2. crepitus during most days of the previous month and
3. morning stiffness with active movement for less than 30 minutes and
4. age over 37 years or
5. crepitus and
6. morning stiffness less than 30 minutes and
7. bone deformation (swelling).
8. absence of crepitus and
9. bone deformation.

Sensitivity - 89%, specificity - 88%.

Clinical and radiological symptoms

1. Pain in the knee joint during the previous month, most often during the day, and
2. Osteophytes or
3. synovial fluid typical for arthrosis (light, viscous, cell count less than 2000/ml; if there is no information about synovial fluid, then age under 40 years is taken into account instead) and
4. morning stiffness less than 30 minutes and
5. crepitus during active movements.

Sensitivity - 94%, specificity - 88%.

[ 31 ], [ 32 ], [ 33 ], [ 34 ]

Criteria for the diagnosis of osteoarthritis (Benevolenskaya L.I. et al., 1993)

Clinical criteria:

1. Joint pain that occurs at the end of the day and/or in the first half of the night.
2. Joint pain that occurs after mechanical stress and decreases with rest.
3. Deformation of joints due to bone growths (including Heberden's and Bouchard's nodes).

Radiographic criteria:

1. Narrowing of the joint space.
2. Osteosclerosis.
3. Osteophytosis.

Note. Criteria 1-2 are the main ones, criterion 3 is additional. The first two clinical and radiological criteria are required to establish a diagnosis of osteoarthritis.

[ 35 ], [ 36 ], [ 37 ], [ 38 ]