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Osteoarthritis N002

Last amended 
5 July 2022
Current RMA Instruments
Reasonable Hypothesis SOP
61 of 2017 as amended
Balance of Probabilities SOP
62 of 2017 as amended
Changes from previous instruments

SOP bulletin 214

SOP Bulletin 231

ICD Coding
  • ICD-9-CM: 715
  • ICD-10-AM: M15, M16, M17, M18 or M19.
Brief description

Osteoarthritis is a degenerative joint disease involving the loss of articular (joint) cartilage and associated changes to the underlying bone and joint margins.  It results from mechanical joint stress.  It results in pain, stiffness and loss of function in the affected joint.

Confirming the diagnosis (also see further comments, below)

A diagnosis of osteoarthritis requires:

  • clinical manifestations, in the form of pain, impaired function and stiffness in the affected joint/s, together with;
  • the presence of degenerative cartilage loss or osteophyte (bone spur) formation in the same joint/s.

Degenerative cartilage loss and osteophyte formation are generally demonstrated by imaging** (X-ray, CT scan, MRI), or on arthroscopy.  In certain circumstances the assessment can be made clinically.  For osteoarthritis of the hip, knee, hand, or foot, that presents with typical features (such as activity-related pain, short duration morning stiffness, bony enlargement,
symptoms affecting one or a few joints), in a person aged 45 or older, imaging or arthroscopic evidence is not essential and the diagnosis can be made on clinical grounds.

The diagnosis of osteoarthritis can be made by a general practitioner.

The relevant medical specialist is an orthopaedic surgeon or rheumatologist.

Additional diagnoses covered by these SOPs
  • degenerative joint disease (except spondylosis)
  • osteoarthrosis (except in the spine)
Additional conditions that may be covered
  • degenerative labral tear - A degenerative labral tear may be an associated feature of osteoarthritis of the hip joint or the gleno-humeral joint in the shoulder.  A degenerative labral tear of the hip may also be an associated feature of femoroacetabular impingement syndrome, or may be an incidental radiological finding.  If a degenerative labral tear is present in conjunction with osteoarthritis of the hip or shoulder, it should generally be considered to be part of the osteoarthritis.
  • degenerative meniscal tear - A degenerative meniscal tear may be an associated feature of osteoarthritis of the knee, or may be an incidental radiological finding.  If a degenerative meniscal tear is present in conjunction with osteoarthritis of the knee, it should generally be considered to be part of the osteoarthritis.
Conditions not covered by these SOPs   
  • acute articular cartilage tear*                
  • acute traumatic chondral defect* (acute articular cartilage tear SOP)
  • chondromalacia* - chondromalacia patella covered by SOP of that name, chondromalacia at other sites is non-SOP
  • osteoarthritis of the spine* (cervical spondylosis, thoracic spondylosis, or lumbar spondylosis SOPs)
  • osteochondritis dissecans#                  
  • osteoporosis*                                              
  • rheumatoid arthritis*                                                            

* another SOP applies  - the SOP has the same name unless otherwise specified

# non-SOP condition

Clinical onset

Once the diagnosis has been confirmed, it may be possible to back-date clinical onset based on the relevant associated symptoms.  The nature and pattern of the symptoms (location, temporal connection, persistence etc.) needs to be consistent with a degenerative origin.  Difficulties in assessing onset may arise where a prior acute joint injury, or surgical repair of such an injury (e.g. meniscectomy, ACL repair) has occurred and symptoms have persisted subsequently.  The time to develop clinically apparent osteoarthritis post injury is variable and dependent on factors such as the nature and extent of the injury and age.  Most commonly, osteoarthritis onset following a joint injury occurs between ages 40 and 50.  Onset may be as soon as 5 years post injury, particularly if of older age at the time of injury, but is more likely to be 10 years or more (and up to several decades later), particularly if the injury occurred at a young age (<25). 

Imaging evidence of joint degeneration does not establish a clinical onset, as clinical manifestations from the degeneration are required.  However, in the case of a prior injury or joint disorder, in the absence of a change in symptoms, and where a diagnosis of osteoarthritis has been made, date of first imaging showing degeneration may provide the only available marker for the time of clinical onset.

Clinical worsening

The natural history of osteoarthritis is to slowly progress and worsen.  Conventional medical therapy and operative treatment other than joint replacement may alleviate symptoms but will not slow or reverse the condition.

Further comments on diagnosis

** The presence of degenerative cartilage loss or osteophyte formation is not adequately demonstrated by a nuclear imaging bone scan.  Such scans are non-specific.  They do not differentiate osteoarthritis from other arthritis or other bone/joint pathology.  In some situations, particularly where a bone scan shows symmetrical activity in the hips, knees or hands, the findings can be regarded as characteristic of osteoarthritis.  But, actual degenerative cartilage loss or osteophyte formation will still not have been demonstrated, and these cases will largely be those where imaging is not required anyway (as detailed above, in persons over age 45 etc).  Bone scanning should not be relied on for an osteoarthritis diagnosis unless exceptional circumstances preclude more appropriate imaging. 

If current imaging has been performed and it is reported by a radiologist as negative for degenerative cartilage loss and osteophyte formation in the affected joint/s that will generally preclude an osteoarthritis diagnosis.  Exceptions may be possible where a specialist orthopaedic surgeon or rheumatologist, having clinically assessed the client and reviewed the imaging, supports the diagnosis. Advice from a MAC may be required in such cases.

Generally, each claimed joint that is affected by osteoarthritis will need to be individually diagnosed and determined, so that each of the causal factors can be considered in relation to that joint.

If, having examined the evidence, it is apparent that two or more joints can be accepted using the same causal factor then such joints can be collectively diagnosed (eg, both knees affected and obesity factor met - diagnose as osteoarthritis both knees).

The diagnosis for each joint or group of joints should describe the site/s involved.  The term generalised osteoarthritis should not be used.