Approach to shoulder pain: Clinical sciences

Shoulder pain is a common symptom with many underlying causes, including conditions affecting the joint, capsule, tendons, or bursa. It’s important to first identify if your patient’s shoulder pain is due to trauma or infection. Other possible types of shoulder pain include neuropathic pain from nerve damage and nociceptive pain from arthralgia, capsulitis, tendinopathy, and bursitis.

When a patient presents with shoulder pain, first obtain a focused history and physical examination. History reveals shoulder pain, while the exam might demonstrate edema, erythema, or warmth over the joints. They may also have shoulder tenderness, effusion, limited joint range of motion, crepitus, or even an obvious joint deformity.

Your next step is to assess for trauma. This includes an obvious mechanism of injury, such as a motor vehicle crash or sports injury; a joint deformity; or ligamentous laxity. If trauma is present, think fracture, dislocation or separation; or a tendon rupture or labral tear.

Now, if your patient reports an inability to lift their arm above their head, and possibly a popping sensation; and if the physical exam reveals painful, limited range of motion; and possibly decreased sensation, decreased muscle strength, or diminished pulses, consider a fracture, dislocation, or AC joint separation and order a shoulder X-ray. If the X-ray results confirm a bone fracture, joint dislocation, or AC joint separation, diagnose a shoulder fracture, dislocation, or separation.

Here’s a clinical pearl! Shoulder separation is actually not an injury to the shoulder joint itself. Instead, it occurs in the setting of trauma to the ligaments of the acromioclavicular joint, known as the AC joint, which is where the clavicle and the scapula meet. The coracoclavicular, or CC joint, also connects the scapula to the clavicle. This type of injury can occur when a patient falls directly on their shoulder. Injuries range from partial tearing of the AC ligaments with the surrounding bones in place, to complete AC and CC tears with bony displacement.

Next up is tendon rupture or labral tear. These patients will report increased pain with overhead activity. They might also note their pain is exacerbated when they’re lying on the affected side, but that it improves with rest or when pressure on the shoulder is relieved. They may even hear a clicking sound with certain movements.

Examination will reveal a painful, limited range of motion of the shoulder and possible tenderness to palpation. Other findings may include a positive drop arm test, meaning they experience pain as they lower their arm from a fully abducted position to an adducted position; a positive external rotation lag sign, where they’re unable to maintain a position of maximal lateral rotation; or a positive O’Brien test meaning they experience pain with internal rotation. The drop arm and external rotation lag sign help diagnose rotator cuff tears, and the O’Brien test will help determine if your patient has a labrum tear.

With these findings, consider tendon rupture or labral tear, and obtain an MRI of the shoulder. If imaging shows a defect of the tendon or labrum, diagnose tendon rupture or labral tear.

Now, if trauma is not present, assess for signs of infection like fever, chills, myalgias, and localized tenderness. If there are signs of infection, think septic arthritis and osteomyelitis!

First up is septic arthritis. Your patient will report a painful swollen joint, and they might have a history of immunosuppression such as diabetes or HIV. Examination will reveal joint effusion, limited range of motion, and erythema with warmth of the overlying skin.

Based on these findings consider septic arthritis and aspirate synovial fluid for analysis of cell count and differential, Gram stain, culture, and the presence of crystals. If the synovial fluid has a purulent appearance, a white blood cell count of 50,000 or more, Gram stain and culture are positive for bacteria, and negative for crystals, diagnose septic arthritis.

Next up is osteomyelitis. Patients might report recent shoulder surgery or may have a history of immunosuppression. Examination often reveals tenderness to palpation over bone, as well as erythema and edema of the overlying skin. You might even note a draining sinus tract on the skin as well.

Based on these findings, consider osteomyelitis of the shoulder and order labs, including blood cultures, CBC, and inflammatory markers like ESR and CRP. Also, order imaging, including an X-ray and an MRI of the shoulder.

If labs reveal positive blood cultures, often with leukocytosis and elevated ESR and CRP; and if the X-ray shows overlying soft tissue swelling with cortical bone destruction and an underlying lucent bony lesion; and the MRI typically reveals bone marrow edema and overlying periosteal and subcutaneous edema diagnose osteomyelitis!