Pain is usually the first and predominant complaint in patients with symptomatic OA. Typical OA pain is exacerbated by use of the joint and relieved with rest. Some patients experience an exacerbation of their pain with changes in barometric pressure. The symptoms may be present at first just with extremes of joint use such as high joint loads or prolonged use, but then may be precipitated with minimal to moderate use, eventually occurring at rest.

As cartilage is aneural, joint pain arises from adjacent structures. Possibilities include a joint capsule stretched by bony enlargement, periosteal reaction, subchondral bone microfractures, increased intra-osseous venous pressure, and synovitis. There is often poor correlation between the amount of pain experienced and the degree of
radiographic OA present.⁸ Bone marrow edema as demonstrated by magnetic resonance imaging (MRI) correlates well with knee OA pain,⁹ and the association is stronger when large bone marrow edema lesions are seen in association with cartilage defects that penetrate to the subchondral bone.¹⁰ Low grade synovitis has been demonstrated in osteoarthritic joints¹¹ and, on occasion, a very inflammatory reaction may occur, often in the setting of a crystal-related disease such as seen in patients with calcium pyrophosphate dihydrate (CPPD) or hydroxyapatite deposition.

The Joint Commission on the Accreditation of Hospitals has mandated that pain be recorded as the fifth vital sign, with the patient asked to describe their current pain on a visual analog scale.¹² The pain scale rating reveals pain at that particular moment, but it is important to get a sense of the intensity and ranges of joint pain during the previous days, weeks, or months, what actions exacerbate the pain, and what activities have had to be modified or discontinued. OA pain can usually be relieved with resting the joint, but in end-stage OA, pain at rest can occur and is debilitating. Patients can generally describe the source of their pain but there are exceptions: cervical spondylosis symptoms may present with arm pain; some patients perceive first CMC joint pain as wrist pain; buttock pain coming from the lumbar spine is often referred to as hip pain, while the pain from hip OA usually presents in the groin.¹³ OA pain may be amplified if there is pain at other sites. In a large survey study, subjects who had knee pain and pain at two or more other sites had more severe knee pain than those who reported the knee as their sole site of pain.⁴

Many individuals feel that their OA pain is exacerbated by cold, damp weather or changes in barometric pressure. Studies of this are contradictory,^14,15 but someone with OA may function better in a warm, dry climate where heavy clothing is not required and walking surfaces are not slippery.

Morning stiffness may occur with OA. It is a sensation that the joints and periarticular musculature are tight and slow to move and usually lasts less than 30 minutes. The stiffness is localized to the region around the affected joint(s) and is not the diffuse morning stiffness characteristic of rheumatoid arthritis. When it occurs during the day following periods of immobilization, it is referred to as gelling. Some individuals perceive stiffness as a painful condition while for others it is a nonpainful resistance to motion.

Individuals with OA may experience decreased function for recreational, vocational, and even self-care activities. They may be limited by their pain; have lost range of motion in the joint because of loss of joint space; have associated muscle weakness due to atrophy of the adjacent muscles; have to work harder to move the joint as the coefficient of friction increases as the cartilage surface fissures and loses integrity; or have joint instability. Joint proprioception is decreased in knee OA, which could impact on function¹⁶ but appears to have minimal clinical impact.¹⁷

The involvement of more than one joint in a limb or region may greatly limit the individual. Instability of the first metacarpophalangeal (MCP) joint compounds the pain and weakness associated with first CMC disease. A fused osteoarthritic ankle will increase the joint load on the ipsilateral osteoarthritic knee and impair compensatory limping which serves to protect the knee joint. Malalignment and instability of osteoarthritic joints may increase pain and disability.¹⁸

In addition to the extent and severity of the OA, age, weight, general muscle strength and conditioning, mental health, and alertness may all be factors in determining who becomes disabled and who does not by their OA. As the population ages, and as pain is recognized as an unacceptable symptom and that a sedentary lifestyle is undesirable, more aggressive intervention, particularly for OA of weight-bearing joints, may be appropriate.

Tenderness or pain with pressure on the joint or along the joint margin is typical, except for the hip, which is too deep to produce tenderness to palpation. Periarticular structures may be tender secondary to muscle spasm or adjacent bursitis or tendonitis.

Joint enlargement may consist of bony enlargement and/or joint effusions. The bony enlargement is due to osteophytes. These are very characteristic in the DIPs and proximal interphalangeal (PIP) joints of the hand. Effusions are generally noninflammatory. If heat or erythema are present, consideration should be given to the possibility of a crystal arthropathy, joint trauma, or infection.

Crepitus is an audible or palpable sensation of roughness, crunching, or crackling over a joint during active or passive movement. The detection of crepitus in the patellofemoral, tibial, or femoral condyles around the knee correlates well with degenerative findings seen at arthroscopy.¹⁹ However, many people have audible sounds from their joints in the absence of any joint pain. Crepitus is presumably caused by irregularity of joint surfaces or intra-articular debris.