Julieta Gentiletti, Alberto Gentiletti 


The musculoskeletal system is made up of joints, periarticular structures such as tendons, bursae, and ligaments, and extra-articular structures such as bone, muscle, nerves, fascia, skin, and subcutaneous cellular tissue. Pathological processes of both inflammatory and non-inflammatory origin can develop in any of these structures, many of which are similar to each other. (ALVAREZ BLANCO) Most diseases of the musculoskeletal system are self-limited entities, with periods ranging from 2 to 6 weeks. When the involvement is localized in the joints (synovitis, degenerative processes, tumors) or there is inflammation in the extra-articular structures (myositis, sclerosis), the processes are not usually self-limited. (ALVAREZ BLANCO)

The most important thing for the evaluation of the musculoskeletal system is to take a good medical history, examine the joints in detail to identify which anatomical structures are involved, and thus recognize joint instability synovitis. (LIANG, M)

Clinic history

Interrogation : The most important point of history is to differentiate between the pain of inflammatory type of non - inflammatory pain. (ALVAREZ BLANCO)

Identify which joints are involved, and whether the involvement is additive, episodic, mono, oligo, polyarticular, and / or with symmetric distribution. Determine how and when it started, triggers such as new medications, recent infections, trauma, diet or increased physical activity and what are the circumstances that make it worse or better, establish temporal patterns and confirm whether or not there are accompanying symptoms such as, for example , constitutional symptoms. (LIANG M, POLLEY HF, ALVAREZ BLANCO, MEEHAN R)

There are several symptoms of musculoskeletal involvement, among the most important are:

Arthralgias : Pain that originates in the joints or around the joints but does not originate in the joint itself. (LIANG, M) Mechanism origin pain improves with rest and worsens with exercise.

The nocturnal pain that awakens the patient can be of neurological, infectious, vascular origin, crystal deposition diseases such as gout or pseudogout, or as a consequence of structural damage to the joint. Bursitis or tendinitis can also wake the patient. (LIANG M, ALVAREZ BLANCO)

Arthritis : There are two characteristic types of arthritis, inflammatory and non-inflammatory. Inflammatory arthritis is characterized by symptoms worsening with rest, while non-inflammatory arthritis worsens with movement and improves with rest. (PINALS R)

Stiffness : Sensation of numbness when mobilizing a joint, then prolonged immobility. It is indicative of joint inflammation or synovitis and probably reflects an alteration in the viscosity of the inflamed synovial fluid and pericapsular inflammation. (ALVAREZ BLANCO)

Clinically stiffness is said to be significant when it lasts more than 30 minutes. In inflammatory diseases the duration of stiffness is proportional to the severity of the inflammation and generally decreases as the disease improves. (LIANG, M)

As an isolated symptom, it is very insensitive and not very specific, since it is present in most elderly patients, hypothyroid patients, Parkinson's disease and many diseases in which there is a minimal inflammatory component. (ALVAREZ BLANCO)

Articular Blockage . It is the impossibility of carrying out the joint game in its entirety. It is produced by an internal alteration (loose bodies, meniscal or cartilage tears) or by a blockage produced by extra-articular soft tissues due to the presence of nodules in the tendon structures (LIANG M, ALVAREZ BLANCO)

Weakness : Involves loss of strength in which patients have difficulty starting and maintaining functional activity. There are four common types of weakness 1) generalized, painless accompanied by fatigue, occurs in cases of disuse atrophy or myasthenia, 2) painless weakness with loss of strength in a muscle group, ranging from complete denervation to damage in some nerve root (polio) and / or localized atrophy 3) weakness associated with paresthesia that occurs in compression neuropathies or radiculopathies such as carpal tunnel syndrome or sciatica and 4) weakness associated with pain or cramps suggesting inflammatory muscle disease or metabolic disease of the muscle. (LIANG, M)

Cramps : The most typical are night cramps with intense pain in the calves or in the intrinsic muscles of the foot that improve with massage, heat, time and stretching of the muscle. Peripheral muscle cramps are generally benign and self-limited. Cramps in various muscle groups such as the abdomen, or upper limb, which appear after strenuous aerobic exercise are generally caused by a primary muscle disease or toxic-metabolic disease. Regional cramps accompanied by muscle pain can be the cause of arterial insufficiency. (ALVAREZ BLANCO)

Myalgias : They are less intense and do not wake the patient at night. Some examples of myalgia are: bacterial or viral sepsis

Concomitant symptoms: Fatigue, rash, lymphadenopathy, alopecia, nasal or oral ulcers, pleuritic pain, Raynaud's phenomenon, dry eye, dry mouth, fever, weight loss and night sweats, etc. (PINALS R) its presence forces us to consider a systemic disease.

Table: Symptoms that help differentiate an Inflammatory Rheumatic Disease from a Mechanical Rheumatic Disease




Morning stiffness

> 1 hour

<30 minutes





May improve symptoms

May make symptoms worse


May make symptoms worse

May improve symptoms

Systemic Commitment



Response to corticosteroids



Physical Exam : Its purpose is to examine all the structures of the musculoskeletal system to identify the site of pain and determine if it is caused by an inflammatory process. Follow the classic sequence of inspection, palpation, and mobilization of the joint. (ALVAREZ BLANCO, LIANG M)

The cardinal signs of synovitis are warmth, flushing, joint pain, soft tissue edema, or joint effusion with decreased movement in all directions. (PINALS R)

It is also important to determine joint mobility (range of motion), loss or decrease of active joint mobility with decreased passive motion suggests soft tissue pathology such as bursitis, tendinitis or muscle injury, while when both passive mobility are compromised As active, we must think of soft tissue contracture, synovitis or some structural alteration of the joint. (PINALS R, MEEHAN R)

In patients with inflammatory arthritis, the most important characteristics for determining disease activity are: duration of morning stiffness, night pain, severity of constitutional symptoms such as fatigue, joint edema, or involvement of a new joint. (MEEHAN R)

Table: Causes of arthritis and monoarthritis

  1. Septic
    • Mycotic Bacteria
    • Lyme disease Mycobacteria
  2. Traumatic
    • Fracture
    • Internal tear hemarthrosis
  3. By deposit of crystals
    • Gout
    • Pseudogota
    • Hydroxyapatite deposition disease
    • Palindromic Rheumatism
  4. Other
    • Osteoarthritis
    • Juvenile Rheumatoid Arthritis
    • Coagulopathies
    • Avascular bone necrosis
    • Foreign body synovitis
    • Pigmentary villonodular synovitis
    • Synovioma

Approach to the patient with joint pain:

Some of the polyarticular diseases can manifest themselves initially as monoarticular, including: Rheumatoid Arthritis (RA), Juvenile RA, Viral Arthritis,

Reiter's syndrome, reactive arthritis, psoriasis arthritis, arthritis associated with enteropathies and Whipple's disease. (HAWKINS R)

Table: Causes of polyarthritis and oligoarthritis

  • Infectious arthritis
    • Bacterial: Lyme disease
    • Bacterial endocarditis
    • Viral: Hepatitis
    • Rubeola Parvovirus . CMV Adenovirus Varicela-zoster Coxackie virus
    • Mycotic
  • Reactive or post-infectious arthritis
    • Rheumatic Fever Reiter's Syndrome
    • Enteric infection
  • Spondyloarthropathies
    • Ankylosing spondylitis
    • Psoriasic arthritis
    • Inflammatory Bowel Disease
  • Rheumatoid arthritis
  • Inflammatory osteoarthritis
  • Crystal-induced arthritis
    • Gout Pseudogout
  • Systemic Rheumatic Diseases
    • Systemic lupus erythematosus
    • Systemic Vasculitis
    • Systemic sclerosis
    • Polyimiositis
    • Dermatomiositis
    • Still's disease
    • Behcet's syndrome
    • Recurrent Polychondritis
  • Other systemic diseases
    • Sarcoidosis
    • Palindromic rheumatism
    • Familial Mediterranean fever
    • Neoplasms
    • Hyperlipoproteinemias


Table: Clinical features of RA vs Osteoarthritis (MEEHAN R)

Rheumatoid arthritis




Occasion iona linen te







Digital infarcts



Bone hypertrophy



Joint commitment IFD IFP MCF Muneca

No Yes Yes Yes

Heberden's nodules Bouchard's nodules No No


Swan neck deformity



Angulation in IFD or IFP

Other rheumatic diseases in which subcutaneous nodules can be found are: SLE, Rheumatic fever, Tophaid gout, Juvenile chronic arthritis, Limited cutaneous scleroderma, Erythema nodosum, Multicentric reticulohistiocytosis, Sarcoidosis, Vasculitis, Panniculitis, Hyperlipoproteinemia type III, Lupus profundus type III. (MEEHAN R)

Diagnosis: Positive RF does not make a diagnosis of RA. Patients with positive RF tend to have a more aggressive form of the disease, with more severe and destructive joint inflammation. Patients with high RF titers are at greater risk of developing extra-articular complications. (HOBBS K)


Carpal Tunnel Disease:

On physical examination, there may be atrophy of the thenar eminence in chronic cases with damage to the motor portion of the nerve. Acute symptoms are sensory. (MEEHAN R)

Symptoms appear with provocation tests: Tinel test: It is done with the wrist in extension. The transverse carpal ligament is then struck using the reflex hammer or the examiner's middle finger. Phanel test: The patient is asked to flex both hands for 60 seconds. And there is numbness of the areas innervated by the median nerve. (MEEHAN R)

Quervain's tenosisnovitis :

Finkelstein test. It is done by asking the patient to make a fist, enclosing the thumb. The examiner then draws the fist toward the styloid process. The patient feels pain in the anatomic snuffbox, this implies that there is tensynovitis in the extensor pollicis brevis and longus of the thumb. Crackles can sometimes be heard with the stethoscope. (MEEHAN R)

Lateral Epicondylitis: (Tennis elbow) Direct palpation of the wrist extensor muscles at the lateral epicondyle. The patient is asked to make a fist and keep the wrist extended. The examiner flexes the wrist, while supporting the patient's arm. Pain arising from the lateral epicondyle of the patient confirms the diagnosis. (MEEHAN R)

Trochanteric Bursitis: The diagnosis is made by physical examination, by direct palpation of the soft tissues in the area of ​​the greater trochanter of the femur. Pain can be caused by hip abduction, flexion, and external rotation maneuvers. (MEEHAN R)

Complementary tests Laboratory

Complete blood count:

Chronic disease anemia

Complement : It can decrease as a result of a decrease in production, caused by a hereditary deficit or as a consequence of liver disease or by increased consumption, as a result of complement activation. The most common cause of increased consumption is elevated levels of circulating immune complexes, which activate the classic pathway. (HOBBS K)

There are a large number of diseases that present with a decrease in complement, the most common being SLE, systemic vasculitis, subacute bacterial endocarditis, sepsis, post-streptoccal glomerulonephritis and membranoproliferative glomerulonephritis. (HOBBS K)

The components of the complement that are requested generally are C3, C4 and CH50. (HOBBS K)

Acute phase reactants ; A group of plasma proteins, including fibrinogen, haptoglobin, C-reactive protein, alpha-1-antitrypsin, that are synthesized in the liver in response to inflammation or tissue necrosis and appear to correlate with corniceal inflammation. (LIANG M, HOBBS C)

The two acute phase reactants that are commonly used in the evaluation of rheumatic diseases are erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). (LIANG M)

CRP rises within 4 hours after tissue damage, peaking between 24-72 hours, therefore its response is faster than ESV, in inflammatory processes, so it is considered more sensitive than ESV to measure inflammation . (KUSHNER I, HOBBS)

By definition the VES is needed to make the diagnosis of Temporal Arteritis and Polymyalgia Rheumatica (PMR). (LIANG, M)

In pseudogout, ESV is not very helpful, and a normal ESV does not exclude the diagnosis. (LIANG, M)

The VES is useful in monitoring activity in Rheumatoid Arthritis (RA), and PMR.

Being less useful in patients with SLE and spondyloarthropathies. (LIANG, M)

Factors that affect the erythrocyte sedimentation rate:
Increase Decrease
Anemia Sick cells disease
Hypercholesterolcmia Anisocitosis
Female gender Spherocytosis
Pregnancy Microcytosis
Increase in ambient temperature Polycythemia
Connective tissue diseases Bile salts
Obesity Clotted blood samples
Chronic renal failure > two hours to do the laboratory test
Heparin Low ambient temperature
Tissue damage (Ex: myocardial infarction) Afibringenemia / Hypofibrinogenemia
Age Congestive heart failure
After trauma Caquexia
Bacterial infections Agammaglobulinemia
Neoplasms: Lymphomas, Myelomas, others Increased plasma viscosity

Autoantibodies: They are immunoglobulins directed against intracellular antigens, on the cell surface or extracellular. Intracellular antigens include nuclear components, which are called antinuclear antibodies, and cytoplasmic components, anti-cytoplasmic antibodies. Antibodies to cell surface antigens react against a wide variety of antigens including HLA molecules. Other autoantibodies can react against plasma components, such as coagulation factors, an example is the lupus anticoagulant. (LIANG, M)

Autoantibodies can be detected by a variety of techniques, including indirect immunofluorescence, passive hemagglutination, latex hemagglutination, ELISA, radioimmunoassays. They are considered positive when they reach values ​​from 1:40 to 1:80. An isolated positive ANA test does not make a diagnosis, since 5% of the normal population can be positive ANA and a negative test does not exclude the diagnosis of autoimmune disease. (LIANG M, HOBBS K)

Diseases associated with positive ANA
THE 99%
Drug-induced lupus 95-100%
Mixed connective tissue disease 9 5-100%
Systemic sclerosis 80-95%
Sjogren's syndrome 75-90%
Autoimmune hepatitis 60-100%
Primary biliary cirrhosis 60-100%
Polymosystem 30-80%
Rheumatoid arthritis 30-50%
Multiple sclerosis 25%
Patients with silicone implants 15-25%
Healthy patients, relatives of patients  15-25% with LES
Neoplasms 15-25%
Elderly> 70 years twenty%

There are drugs that can cause a positive ANA test. The most commons are:

Procainamide, Hydralazine, 'Phenothiazines, Diphenylhydantoin, Isoniazid and Quinidine. ANAs can remain positive from 6 months to a year after drug discontinuation (HOBBS K).

By indirect immunofluorescence, various ANA patterns can be detected.

Which are associated with different diseases. These patterns are 1) Homogeneous that is associated with SLE, Drug-induced Lupus, and other diseases, 2) Peripheral associated with SLE and Autoimmune Hepatitis, 3) Mottled, found in Systemic Sclerosis, Mixed connective tissue disease, 4) Nucleolar is found in Scleroderma (PSS) and hepatocellular carcinoma, 5) Centromere, in limited cutaneous scleroderma. (HOBBS K)


Other autoantibodies are anti-cytoplasmic antibodies, within which are antibodies directed against specific antigens present in the cytoplasm of neutrophils called antineutrophil antibodies or ANCA. There are two different types of ANCAs. l) Those that react against myeloperoxidase (MPO), elastase, lactoferrin and others, which give a perinuclear pattern in indirect immunofluorescence studies are called P-ANCA and 2) those that react with proteinase-3 (PR3) that give a Diffuse cytoplasmic pattern on immunofluorescence and are called cytoplasmic or C-ANCA. In patients who are ANCA positive, ask for specific antigens for MPO or PR3. (HOBBS K) The diseases associated with ANCAs are:

Wegener's granulomatosis Microscopic polyarteritis
Microscopic polyarteritis Glomerulonefrrtis pauci-immune
Churg-Strauss vasculitis Churg-Strauss vasculitis
  Drug-induced snies such as: hydralazine, PTU, penicillamine, minocycline
  Ulcerative Colitis
  Autoimmune diseases such as: SLE, AR
  HIV infection

Rheumatoid factor: It is an autoantibody directed against the antigenic determinants in the Fc fragment of immunoglobulin G. It can be of any isotype: IgM, IgG, IgA or IgE. In routine laboratories, IgM is measured by latex, agglutination or ELISA. (HOOBS K)

The diseases with positive RF are: Rheumatoid Arthritis, Chronic Hepatitis, Pulmonary Diseases, SLE, PSS, Mixed connective tissue disease, Sjogren's Syndrome, Polymyositis, Sarcoidosis, Neoplasms generally after radiation or chemotherapy, Infections such as HIV, mononucleosis, tuberculosis, bacterial endocarditis, parasitic infections, chronic viral infections, cryoglobulinemia and hepatitis C. (HOBBS K)

RF can be positive in normal patients, especially in patients older than 70 years. (HOBBS K)

Serum Uric Acid: it is generally elevated in gout, but as in the general population there is a high prevalence of asymptomatic hyperuricemia, its use is very limited. Even during acute attacks of gout its value is usually normal, especially in patients with polyarticular involvement. (HADLER NM)

Articular Puncture: It is performed in all cases of acute monoarthritis of doubtful etiology to confirm or rule out infection and initiate appropriate treatment.

Contraindications: Hemophilia, Anticoagulant therapy, Thrombocytopenia, Cellulitis in the compromised joint. (SPENCER R)

Complications of joint puncture. Infection, Hemorrhage, Vasovagal syncope, Pain and cartilage damage- (SPENCER R)

In all synovial fluid analysis, culture, Gram stain, leukocyte count and formula, glucose, total proteins, and lactate dehydrogenase should not be missing. Also in cases where the presence of crystals is suspected, polarized microscopy must be performed.

Table: Synovial fluid characteristics
  Normal Non-inflammatory Inflammatory Septico Hemorrhagic
Volume (ml) <3.5 >3.5 >3.5 >3.5 >3.5
Clarity Transparent Transparent Translucent-opaque Opaque Bloody
Colour Clear Yellow Yellow to opalescent Yellow to Red
Viscosity high high Low Variable Variable
Leukocytes <200 200-2000 2000-10000 >100000 200-2000
% PMN <25 <25 >50 >75 50-75
Culture Negative Negative Negative Positive Negative
Total protein (g / dl) 1-Feb 1-mar 3-may 3-may 4-jun
LDH Very low Very low high Variable Similar
(compared to blood levels)
Glucose mg / dl Almost equal to plasma. Almost equal to the plasmatic > 25, less than plasma <25 much lower than plasma Almost equal to the plasmatic


Types of synovial fluid pathologies   
Non-inflammatory liquid Inflammatory fluid  Hemorrhagic fluid or hemarthrosis 
  • Atrosis
  • Joint trauma
  • Mechanical alterations
  • Pigmentary villonodular synovitis
  • Necrosis avascular 
  • WITH
  • Gout
  • Pseudogota
  • Psoriasic arthritis
  • Ankylosing spondylitis
  • Reiter's syndrome
  • FR
  • THE
  • Polimialgia Rheumatica
  • Giant cell arteritis
  • Wegener's granulomatosis
  • Hypersensitivity vasculitis
  • Polyarteritis nodosa
  • Familial Mediterranean fever
  • Sarcoidosis
  • Infectious Arthritis
  • Sudacute bacterial endocarditis
  • Palindromic rheumatisms
  • Trauma
  • Hemorragicas diathesis
  • Tumors
  • Pigmentary villonodular synovitis
  • Hemangiomas
  • Iatrogénico


Comparison of microscopic findings in gout and pseudogout
  Gout Pseudogota
Crystals Urato Calcium pyrophosphate
Shape Needle Rhomboid or Rectangular
Birefringence Negative Positive
Color of the crystals Yellow blue


Plain radiographs : They are used to define the character and distribution of erosions, alterations in the joint space, alterations in joint alignment, soft tissue edema or calcifications. (RAK K)

In acute processes, generally, they do not provide an accurate diagnosis. (FINALS R)

They are helpful in osteoarthritis both for diagnosis and monitoring of the disease, in RA, chronic gout. (PINALS R)

In the interpretation of plain radiographs, the presence of alignment, bone mineralization, calcifications, distribution of the compromised joints, presence of erosions and alterations in the soft tissues must be taken into account. (RAK K)

Radiographic features of Inflammatory Arthritis VS Non-inflammatory Arthritis.
Inflammatory Arthritis Non-inflammatory arthritis

Soft tissue edema Periarticular
Loss of uniformity of cartilage (decrease in diffuse interarticular space) 
Bone erosions

  • Juvenile and adult AR
  • Connective tissue diseases
  • Espondiloartropatias seronegativas
  • Septic arthritis

Sclerosis / Osteophytes
Loss of cartilage (decreased focal joint space in the area of ​​maximum
stress ) Geodes / Cysts

  • Primary and secondary osteoarthritis
  • Metabolic or endocrine bone diseases
  • Other diseases such as hemophilia, avascular necrosis.

Ultrasound : It is very useful for the diagnosis of superficial structural alterations, tendon pathology, masses in the soft tissues, inflammation of the bursae and joints. (RAK K)

Computed Tomography : It allows taking cross-sectional images with excellent resolution. It is useful for diagnosing arthritis in complex joints such as sacroiliac, sternoclavicular joints. Also for the evaluation of bone tumors and in the diagnosis of trauma, especially of the pelvis and spine. (RAK K)

Magnetic Resonance : It has excellent resolution for internal knee changes, changes in the internal rotator cuff of the shoulder, avascular necrosis, herniated nucleus pulposus, lumbar stenosis, spinal stenosis and osteomyelitis. (RAK K)

Bone Scintigraphy : It is requested of choice for the follow-up of metastatic disease and osteomyelitis. (RAK K)

It can be ordered, although it is not very specific, for the diagnosis of bone alterations, such as tumors, trauma, infections, or any other pathology that causes an increase in uptake. (RAK K)

Other common indications are evaluation for Paget's disease or metabolic bone disease. (RAK K)

Synovial Biopsy:

Indications: Chronic arthritis (> 6-8 weeks) inflammatory, non-traumatic, limited to one or two joints in which the diagnosis has not been reached by medical history, physical examination, laboratory or analysis of the synovial fluid with negative cultures (including mycobacteria and fungi) (STERLING W)

Diagnoses that can be made with synovial biopsy

  • Chronic infections
    • Fungal arthritis
    • Mycobacterial arthritis
    • Spirochetal arthritis such as Lyme disease or Syphilis
    • Whipple's disease
    • Chlamydia
  • Sarcoidosis
  • Infiltrative or deposit diseases
    • Amyloidosis
    • Hemocromatosis
    • Crystal-induced arthritis
  • Tumors
  • Pigmentary villonodular synovitis
  • Synovial osteochondromatosis
  • Synovial cell sarcoma
  • Leukemias / Lymphomas
  • Metastatic disease in the joint
  • Others
    • Multicentric reticulohistiocytosis
    • Foreign body synovitis 

Synovial biopsy is performed by closed needle biopsy, needle arthroscopy, arthroscopy, surgical biopsy. (STERLING W)