Soft tissue and non-inflammatory conditions

Musculoskeletal pain of non-inflammatory origin is common in childhood and is a frequent cause of referral to paediatric rheumatologists, orthopaedic surgeons, sports medicine specialists, and primary care physicians. Children and adolescents may develop mechanical pain secondary to muscle tendon imbalances exaggerated by abnormal anatomical alignment, neuromuscular or proprioceptive disorders, rapid growth, or change in activity level. 

Common Sports and Overuse injuries

• Upper limb Overuse injuries usually affect the shoulder, the elbow and the wrist. 
• Shoulder: 'Little League Shoulder' is common in young athletes involved in throwing sports, as well as tennis and swimming. 
• Elbow: Overuse of the arm related to excessive wrist extension can cause lateral elbow pain, which is commonly called tennis elbow or lateral epicondylitis. Overuse of the arm may also result in medial elbow pain or “golfer elbow.” This condition is much less common than tennis elbow but affects a similar age group.
• Wrist: Overuse tendon injury such as de Quervain tenosynovitis, extensor carpi ulnaris tendonitis, and intersection syndrome may occur in children participating in sports requiring repetitive wrist motion such as throwing, rowing, and racquet sports. It can also be seen with excessive use of electronic games consoles. 

Traction apophysitis Fractures

• Apophyseal avulsion fracture and apophysitis result from forceful or repetitive traction of the attached muscle. Apophysitis presents with dull, activity-related pain, and avulsion fractures present with localized pain, swelling, and decreased active range of motion.
• Common sites of injury are the iliac crest (abdominal muscles), anterior superior iliac spine (sartorius), anterior inferior iliac spine (rectus femoris), ischial tuberosity (hamstrings), and lesser trochanter (iliopsoas).
• Radiographs may show widening of the apophyses in apophysitis and displacement of the apophyseal centre and bony reaction in apophyseal avulsion fracture. MRI is useful if radiographs are normal.

Stress fracture 

• Stress fractures occur after increased repetitive loading over a relatively short period of time and are more common in children who report a recent increase in activity.
• Several site-specific stress fractures are high risk for non-union and complete fracture, or avascular necrosis, including the proximal fifth metatarsal, tarsal navicular, scaphoid, anterior tibial diaphysis and femoral neck.
• Children with stress fractures usually present with progressively worsening pain, aggravated by weight-bearing activity and relieved with rest. Pain may be present at rest or even at night. On examination, the fracture site is tender to palpation, and there may be swelling.
• Early radiographs may be normal, and late radiographs detect callus formation, physeal widening, or apophyseal fragmentation. Early lesions are best detected by MRI.

Back and chest pain 

• Nontraumatic back pain is common in the paediatric population. Nevertheless, spondyloarthritis, and lymphoma may present similarly and should be excluded.
• The most common mechanical back pain causes are: Spondylolysis and Spondylolisthesis, Lumbar Disk Herniation, Discitis, Lordotic Low Back Pain/Posterior Element Overuse Syndrome and Scheuermann Disease, 
• Chest pain is a relatively common benign and self-limited condition that typically affects 6- to 12-year-olds with no sex predominance. Affected children have a history of recurrent, well-localised, sharp chest wall pain of sudden onset lasting a few seconds to minutes, with negative findings on examination or laboratory testing. 
• Costochondritis also known as chondrodynia, costosternal syndrome, or anterior chest wall syndrome presenting with a brief, acute, and stabbing pain affecting one side of the anterior chest that is worse with deep breathing. 

Soft tissue spectrum

• Tendonitis usually affects children between the ages of 10 and 13. It is caused by injuries due to physical activities that require jumping and repetitive movements such as basketball volleyball or figure skating. Overuse causes very small tears and inflammation of the tendon. Nevertheless, tendonitis is rare in children and apophysitis occurs voluntarily in case of overuse.
• Bursitis is swelling and irritation of a bursa which is a cushioning structure around the joint. Bursitis usually affects the shoulder, elbow, hip or knee and is caused by overuse, injury, arthritis or infection
• Ganglion cysts are mucinous tumours that usually arise from the underlying joint capsules or tendon sheaths, and usually occurs in the hand and knee. Their frequency seems underestimated because their presence is usually painless and does not interfere with function. Ultrasound confirms the diagnosis in the majority of cases and can guide its puncture.

Brachial plexus injury

• Athletes participating in contact sports may experience brachial plexus or cervical nerve root injuries with transient burning pain or parenthesis in a unilateral shoulder and arm after injury often associated with weakness of the proximal arm muscles. These symptoms typically resolve in a few minutes or up to 24 hours and can be diagnosed clinically.
• Symptoms beyond 24 hours, individuals with persistent neurological deficits, recurrent episodes and those with bilateral upper extremity involvement require further investigation.