Diagnosing joint pain

The main complaints of patients with joint syndrome may also include complaints of limited movement in the affected joint or joints, morning stiffness, swelling and change in the configuration of the joint, crunching, clicking in it during movement (crepitus), and changes in gait. The duration of morning stiffness is understood as the time it takes for the patient to "work out" the joint. In case of inflammatory joint damage, the duration of morning stiffness exceeds 1 hour, while non-inflammatory conditions (arthrosis) may be accompanied by short-term, transient morning stiffness that lasts several dozen minutes or less. Much less common are complaints of a sensation of a foreign body in the joint (joint mouse) in avascular necrosis syndrome (osteochondritis dissecans), which is characterized by local necrosis of the articular cartilage and underlying bone tissue. A fragment of necrotic bone is separated and moved into the joint cavity. In these cases, joint pain is accompanied by periodic blockades of the joint. In addition, complaints of muscle pain (myalgia), pain in the ligaments and tendons are important. Redness of the affected joints makes one suspect septic arthritis, acute rheumatic fever (rheumatism), but is sometimes a sign of a malignant tumor.

General complaints may include an increase in body temperature, as well as other complaints that reflect the presence and severity of the intoxication syndrome, such as weakness, lethargy, unmotivated capriciousness, malaise, and changes in the patient's behavior.

After the survey and general examination, the doctor moves on to a more detailed examination of individual parts of the body.

The following characteristics of the joints are visually determined: volume, symmetry, configuration. Joint asymmetry often occurs when one of the limbs is shortened (hemiatrophy - underdevelopment of the limb, hemihypertrophy - unilateral enlargement of the limb). The presence of swelling, i.e. an increase in the volume of the joint with some smoothing of its contours (more often this occurs due to edema of the periarticular tissues or effusion into the joint cavity), its deformation - a persistent and rough change in the shape of the joint (in the presence of bone growths), joint defiguration - an uneven change in configuration (due to proliferative or exudative processes) is excluded. The absence/presence of changes in the soft tissues above the affected joint is stated - pallor or hyperemia of the skin, pigmentation, fistulas. Muscle atrophy, limited joint mobility, forced position of the limb, flat feet are revealed.

The presence of flat feet (absence of visible longitudinal and transverse arches of the foot), clubfoot, high arch of the foot ("hollow" foot), varus or valgus deformity becomes the cause of persistent arthralgia not only in the feet, but also in the knee and hip joints.

Palpation can detect a local increase in temperature over the affected joint (for example, in rheumatoid arthritis) or a decrease in temperature in the presence of trophic disorder syndrome, vascular thrombosis. Normally, the temperature of the skin over the knee joint is lower than that of the tibia. In addition, palpation can detect the presence of pain. Pain during palpation in the joint area is the best indicator of synovitis. Two types of palpation are used during the examination:

• superficial palpation - applying the back of the hand or lightly stroking the affected area with the fingertips; this method determines temperature, pain, the presence or absence of joint swelling, bone changes (for example, exostosis);
• deep palpation - allows to detect effusion in the joint cavity, local pain, not detected by superficial palpation.

The palpatory method helps in detecting "rachitic beads" ("rachitic rosary"), "bracelets", "strings of pearls", rachitic deformations of the cranial vault, etc. In deep palpation, it is advisable to use the "rule of thumb". In this case, palpation is performed so that the palpatory force causes the pallor of the nail bed of the doctor's thumb. Deep palpation is carried out carefully in case of pronounced pain in the affected joint or bone.

It is very important to study the function of joints during all their passive and active movements (flexion and extension, abduction, adduction, rotation). Passive movements are those performed by the doctor without the help of the patient, and active movements are those performed by the patient himself. An obvious discrepancy between the volume of active and passive movements allows us to think about the localization of the pathological process in the periarticular tissues, while the same limitation of the volume of active and passive movements is characteristic of the actual joint pathological process.

During examination, it is possible to determine increased joint mobility (hypermobility) - in Ehlers-Danlos syndrome, Marfan syndrome, Down syndrome, familial joint hypermobility, as well as limited mobility - in contractures, ankylosis, spastic paresis and paralysis, congenital hip dislocation, juvenile slipped capital femoral epiphysiolysis.

In practice, several simple tests are used to diagnose joint laxity - hyperextension of the elbow and knee joints (more than 10°), extension of the thumb until it touches the anterior surface of the forearm, flexion of the torso with the palms freely touching the floor, extension of the fingers when the axis of the fingers becomes parallel to the axis of the forearm, dorsal flexion of the foot by more than 20° from the right angle between the dorsal surface of the foot and the anterior surface of the shin. To diagnose joint hypermobility syndrome, at least 3 criteria must be present. In addition, in pathological conditions accompanied by weakness of connective tissue, a positive Gorlin symptom is observed. It is considered positive if the subject can touch the tip of the nose with his tongue.

Sometimes, other special tests help diagnose damage to various joints.

The rotation test - the patient's passive performance of full external rotation of the shoulder - allows the doctor to doubt the presence of pathology of the scapulohumeral joint.

If hip joint damage is suspected, the "log rolling" test and Trendelenburg test are performed. The "log rolling" test is performed in the leg extension position. The doctor, having grasped the patient's thigh and shin, rotates them outward. The hip joint is the point of rotation. If there is a limitation in the amplitude of internal and external rotation of the leg due to pain in the groin area, this confirms pathology of the hip joint itself. Normally, in a patient standing on one leg, contraction of the gluteus medius on the side of the load-bearing leg leads to the rise of the opposite half of the pelvis. Hip joint pathology, in which weakness of the gluteus medius develops, can be suspected if this rise does not occur (positive Trendelenburg test).

Syndromes of multiple malformations accompanied by joint hypermobility and arthralgia, arthritis

Nosological form, McKusick catalog number	Joint hypermobility and other major diagnostic criteria
Familial joint hypermobility syndrome (MIM: 147900)	A familial form of varying degrees of joint hypermobility. Sometimes combined with hyperextensibility of the skin
Marfanoid joint hypermobility syndrome (MIM: 154750)	Marfanoid phenotype, increased elasticity and fragility of the skin, mitral valve prolapse, aortic aneurysm, etc.
Larsen syndrome (MIM-150250, 245600)	Congenital dislocations of large joints, unusual face, saddle nose, cylindrical fingers
Nail-patella syndrome (M1M:161200)	Patellar dislocation and hypoplasia, onychodystrophy (gene localized on 9q34)
Familial recurrent patellar dislocation syndrome (MIM:169000)	Joint hypermobility, recurrent patellar dislocation
Hydrocephalus, tall stature, joint hypermobility and kyphoscoliosis syndrome (MIM: 236660)	Hydrocephalus, tall stature, thoracolumbar kyphosis, signs of prolapsed heart valves without pronounced regurgitation
Progeroid form of Ehlers-Danlos syndrome (MIM: 130070)	Premature aging, hyperextensibility and fragility of the skin. Defect in the biosynthesis of proteudermatan sulfate. Decreased intelligence, development

The presence of effusion in the knee joint cavity is confirmed by a positive ballottement symptom. When checking the ballottement symptom of the patella, the area located above the patella is compressed by the doctor from the front, which causes the effusion to move into the space below it and creates the impression of a "floating" patella. Tapping the patella with the fingertips leads to its "hitting" the condyles of the femur, which is regarded as a positive ballottement symptom. Damage to the lower surface of the patella (for example, in osteoarthrosis) can be determined by performing a femoropatellar compression test. The patient is asked to straighten the knee joint, which is in a state of flexion. In this case, the doctor presses on the patella in the direction of the condyles of the femur. If pain occurs when the patella moves proximally along the surface of the bone, the test is considered positive.

Differential diagnosis of some arthralgias

Disease	Anamnesis	Physical examination data	Laboratory and instrumental research
Diffuse connective tissue diseases
Rheumatoid arthritis	Morning stiffness, pain in peripheral joints. Fatigue	Synovitis. Joint deformity. Rheumatoid nodules.	Rheumatoid factor. Indicators of inflammation. X-ray.
Systemic lupus erythematosus	Fatigue. Pain in peripheral joints, edema. Raynaud's phenomenon. Headache. Skin changes, serositis, etc.	Skin changes. Synovitis. Neuropathy.	AHA, OsDNA, Sm Ro-antibodies C3, C4 General urine analysis. Indicators of inflammation
Systemic scleroderma	Raynaud's phenomenon. Fatigue. Peripheral joint pain, edema. Esophageal and pulmonary symptoms.	Scleroderma. Swelling of the hands. Pathology of the periungual fold under microscopy	AHA, anticentromere, Scl-70 antibodies. Esophageal motility study. Pulmonary function tests.
Sjogren's syndrome	Pain in peripheral joints, swelling. Fatigue. Dryness of the oral mucosa and conjunctiva.	Enlargement of the salivary glands. Dry keratoconjunctivitis. Synovitis	AHA, RO-, La-antibodies. Shermer and Rose test. Indicators of inflammation
Polymyositis	Muscle weakness. Muscle pain. Fatigue.	Muscle weakness	CPK, aldolase, AHA EMG/SPNI. Muscle biopsy. Inflammatory indicators
Rheumatic polymyalgia	Morning stiffness. Pain in the shoulder, hip, limbs and neck. Headache	Pain along the temporal artery with GCA	Elevated ESR. Indicators of inflammation. Temporal artery biopsy for suspected GCA.
Seronvagative spondyloarthropathy
Ankylosing spondylitis	Morning stiffness. Pain in peripheral joints, swelling. Pain in the lower back. Pain in the cervical spine.	Limitation of movement in the cervical and lumbar spine Synovitis of peripheral joints Iritis	X-ray of the lumbosacral joint. X-ray of the spine, peripheral joints. Indicators of inflammation
Colitis arthritis	Abdominal pain, diarrhea Axial musculoskeletal pain Pain in peripheral joints, swelling	Synovitis of peripheral joints, limitation of movement in the cervical and lumbar spine. Melena (hidden ovary in feces)	Colonoscopy (X-ray contrast studies). X-rays of the spine, peripheral joints. Indicators of inflammation
Other diseases
Sleep apnea syndrome	Fatigue. Unproductive sleep (no rest)	No pathology	Research into sleep structure
Hypothyroidism	Fatigue. Pain in peripheral joints, swelling	Enlarged thyroid gland	Thyroid function assessment

Non-articular pain in the elbow joint is manifested by medial epicondylitis of the elbow. It often occurs as a result of overstraining the flexor-pronator when serving the ball, playing rugby, golf ("golfer's elbow"). This creates an increased load on the medial ligament of the elbow joint, which can be accompanied by a tear of the apophysis. Lateral epicondylitis of the elbow is called "tennis elbow" and is manifested by the occurrence of pain in the area of the lateral epicondyle during a provocative test - the patient clenches his hand into a fist and holds it in an extension position, while the doctor tries to bend his hand, holding the forearm.

All of the above means that in differential diagnostics it is necessary not so much to concentrate on the joint syndrome, but to conduct differential diagnostics between a fairly large list of nosological forms in order to determine what is the basis of the disease, whether the syndrome is a primary or secondary process accompanying a whole list of diseases in various fields of medicine.

When conducting differential diagnostics, sometimes certain laboratory tests help to establish the cause of arthralgia.

Some laboratory tests useful in the differential diagnosis of arthralgias

Study	Detectable diseases
Complete blood count including platelet count	Leukemia Infectious diseases of bones, joints, muscles Systemic connective tissue diseases
Erythrocyte sedimentation rate	Infections Inflammation of the gallbladder Systemic connective tissue diseases Tumors
X-ray	Various benign and malignant bone tumors Osteomyelitis (chronic) Discosis (late stages) Fractures Scoliosis Rickets Displacement of the epiphysis of the tibial head Legg-Calve-Perthes disease Leukemia
Radioisotope bone scan	Osteomyelitis (acute and chronic) Discosis Osteoid osteoma Malignant bone tumors and metastases Bone necrosis due to insufficient blood supply
Serum muscle enzyme activity	Reflex sympathetic dystrophy Inflammatory muscle diseases (idiopathic or viral) Muscular dystrophies Rhabdomyolysis

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