shoulder impingement

Why Shoulder Impingement Syndrome Hurts

In Upper Extremity Pains by Brad Rickert

Have you ever lifted your arm above your head and felt a sharp pain? If so, tissue in your shoulder might be getting pinched by your shoulder’s bone structure. If so, you could be suffering from shoulder impingement syndrome.

In the following article, we’ll talk about what causes shoulder impingement, who’s affected by impingement, and what therapies help ease the pain.

What is shoulder impingement?

Impingement means two objects encroach on each other or collide together.

In shoulder impingement syndrome, the two bones that collide together are the acromion (roof over the shoulder) and the head of the humerus (long bone in your upper arm).  The amount of distance between these two bones is the sub-acromial space. Therefore, the condition can be referred to as “sub-acromial impingement.”

The problem is not just that the acromion and humeral head impinge. The pinched soft tissue in between the bones manifests the syndrome. The soft tissue which gets encroached upon is defined as the supraspinatus (rotator cuff) tendon, the sub-acromial bursa and the long head of the biceps tendon. This explains why tendonitis and bursitis are considered components of impingement syndrome.

Little room exists in the sub-acromial space. When a soft tissue gets pinched, the tissue becomes swollen and inflamed. The swelling and inflammation leaves even less space between the two bones. This creates a self-perpetuating cycle of further impingement and pain.

Impingement syndrome pain feels constant and dull. Pain intensity grows if you perform a movement that makes the acromion and humeral head impinge with swollen, inflamed tendons and bursa .

The pain becomes exacerbated by raising your arm overhead. Also, you’ll feel the pain when reaching across your body or reaching behind your back.

When raising the arm straight up, you may experience a painful arc of movement between 60 and 120 degrees of elevation.

The most common symptoms in impingement syndrome are pain, weakness and loss of motion in the involved shoulder.

What causes of shoulder impingement?

Three major factors which can potentially influence the onset of shoulder impingement syndrome:

Posture and your shoulder

In today’s world, an epidemic of poor posture fills our world. Posture problems begin with students hunched over books and computers. In turn, this habit follows people into careers requiring computer work, talking on phones and being slumped toward a monitor.

With bad posture, the head out in front of the body with shoulders round forward and tilt downward. This dysfunctional scapula position (shoulder blade) allows chest muscles to become tight. Upper back muscles weaken. Since the acromion sitsshoulder impingement at the top outer edge of the scapula, the downward tilt of the scapula in poor posture encourages impingement of the humeral head on the acromion. Especially, when you raise your arm overhead.

Your Acromion Anatomy

Humans come in a variety of shapes and sizes and can differ with geography and gender.

In specific regards to the acromion, the anatomy can be classified into three different shapes:

  • Flat
  • Curved
  • Hooked

An x-ray helps identify the acromion anatomy.

A flat acromion allows the most room in the sub-acromial space. The flat acromion is the least likely to impinge, although impingement can happen.

Curved and hooked acromion remain the most likely to experience impingement. Simply, because both jut downward toward the humeral head and leave less space.

When arthritic changes happen in the shoulder, bone spurs can develop on the under surface of the acromion like stalagtites in a cave. These spurs can also lead to impingement.

Bio-mechanics and Your Shoulder

Often, when a person performs activities with their arms/arm over their head, impingement can result. As muscles around the shoulder fatigue, maintaining the proper bio-mechanics becomes a problem.

This can happen with repetitive or sustained overhead activity such as throwing, hammering, or playing certain musical instruments. Also, a single lift or “jerk” of an object overhead can create a bio-mechanical impingement.

During examination, physical therapists often discover good muscle strength in the big muscles around the shoulder, but poor strength in critical muscles such as the rotator cuff.  Muscular imbalance can lead to shoulder instability and impingement when left untreated.

Diagnosing shoulder impingement syndrome

Different diagnostics can assist in the multi-disciplinary diagnosis of impingement. Physical therapists can complete different tests to more specifically identify the cause and area of impingement. MRIs can be utilized and are helpful, but aren’t necessarily required for diagnosis by a PT. X-rays can show bony types of acromion as well as showing if there is a decrease in the sub-acromial space that could be leading to impingement.

When left untreated

If left untreated, impingement can result in nerve compression symptoms. This includes muscle wasting, weakness, nerve pain and limited range of motion. If not addressed, this lack of motion can manifest in a frozen shoulder. Also, a lack of adequate strengthening and mobility can result in a rotator cuff pathology (tendinitis, tear) if neglected.

Getting a good nights sleep

Increased pain at night can make sleeping difficult. If you attempt to sleep on the involved shoulder, pain increases due to compression of the tendonitis/bursitis in the shoulder.

The pain which accompanies impingement syndrome is primarily driven by the inflamed tissues. Inflammation tends to increase at night due to the slowing of blood circulation.

Your physical therapist can educate and give options to trial for sleeping positions. Also, you’ll learn how to support with pillows to prevent rolling into a painful position.

Use of ice and NSAID’s as recommended by your doctor can assist in providing relief at night. Often, patients report relief extending during the day of their physical therapy session which can allow for improved sleep.

shoulder impingement

Athletes and sub-acromial impingement

Common athletic patients complete repeated shoulder movements, often overhead, consistently throughout their sport.

Often throwing athletes (baseball/softball, football), swimmers, and other overhead athletes (volleyball, tennis) experience impingement.

As a result of the increased demand on the rotator cuff musculature, the muscles cannot provide adequate support and stability for the head of the humerus.

This significantly affects performance, as the injured athlete experiences lack of motion, strength, and often severe pain with overhead movement.

Impingement must be treated in the pain-free range of motion before progressing to overhead stability and higher-level rotator cuff strengthening. The treatment is followed by sport-specific demand and loading as prescribed by your therapist.

Work related shoulder pain

Similar to athletes, any profession with increased upper extremity or overhead demand can experience impingement pain. Jobs with poor ergonomics can cause problems, too. Those who work in construction, warehouses, stocking supplies, painting and any desk job are common candidates for impingement. These professions place increased stress on the shoulder with repeated lifting or extended periods of time with the arms overhead. These activities can irritate the structures in the sub-acromial space.

Other symptoms between pain in the shoulder and limited motion can also be nerve irritation which radiates into the neck or through the affected arm.

As expected with pain from movement, this can have a severe limiting effect on one’s ability to complete job tasks.

Often, this often leads to limited work capability while the patient seeks professional help. As physical therapists, we can assist our patients  in ergonomic workplace setup, and demonstrate tasks you can safely complete to improve your function and efficiency at work.

Activities of daily life and shoulder impingement

Similar to athletics, impingement can significantly limit a person’s function on a daily basis. Any activity involving reaching forward or across your body, pulling, pushing and arm movement overhead could incite pain. A common challenge is self-care, especially bathing/showering and dressing. Washing your hair, lower back, donning/doffing a bra and putting on shirts can all be restricted or painful due to impingement.

Treating shoulder impingement syndrome

Treating pain and preventing apprehension with movement improves function, quality of life, while allowing for decreased inflammation of the structures in the sub-acromial space.

  • Manual therapy assists in decreasing restrictions in movement of the humeral head on the glenoid (socket) within the shoulder capsule. Often, restrictions in the posterior capsule can create anterior and superior movement of the head of the humerus, further decreasing the amount of room in the sub-acromial space.
  • Kinesio taping for shoulder pain can be done to increase activation of rotator cuff muscles to improve stability. Also, taping helps inhibit activity of hypertonic (tight) muscles that promote poor posture/positioning.
  • Rotator cuff strengthening helps restore normal arc of motion and prevent upward translation of humeral head with overhead movements.
  • Mobilizing and stablilizing the scapula. “Proximal stability before distal mobility” is a common phrase uttered throughout physical therapy schooling. This mantra fits well with impingement. The shoulder complex relies on scapular stability as much as the ability of the head of the humerus to move appropriately.

shoulder impingement

The scapula as a floating platform

Think of your scapula as a “floating platform” in the ocean and your arm from the shoulder down as a crane. Try operating an unanchored crane on a platform not anchored to the ocean floor. There would be major problems.

A similar situation can exist in your shoulder, if the muscles that attach to the scapula do not keep it “anchored” and stable. There must be proper muscle balance and scapular stability for the shoulder to function normally.

If the scapula demonstrates excessive movement (upward rotation and “winging” or the scapula flaring out off the ribs), patients often experience pain and weakness accompanied with impingement. Scapular stability exercises focus on weight-bearing and serratus anterior muscle engagement. This allows for improved control and scapular rhythm.

If the scapula demonstrates inadequate tilting, internal/external rotation or upward rotation during lifting activities, this causes a reduction of the sub-acromial space, leading to impingement. If you lack appropriate scapular mobility, your physical therapist can utilize manual therapy techniques to decrease restrictions and restore normal movement.

Best Shoulder Exercises

  • Range of motion exercises – These are best to include early on to maintain and improve ROM. Given that active movements may be more painful, your therapist often follows a progression of movement styles, starting with passive ROM (PROM). Exercises like pulleys and wands can utilize the unaffected extremity to create movement into each plane that is  limited.
  • Active assistive ROM (AAROM) – These can include wands, dowel rods, or even physically lifting the affected arm with the other arm doing the majority of the work. This allows for activation of the appropriate muscles, while preventing excess loading which may increase pain. Next, active ROM (AROM) consists of actively moving through the entire range and in each plane.
  • Lastly, movements progress to resisted motion, which will be emphasized in the strengthening portion. Note: your therapist may combine each of these types of movements throughout your program, i.e. you will not have to achieve full PROM before any AAROM are included.
  • Strengthening exercises – Just as ROM features variations of movement, so does strengthening. Some examples are isometric and isotonic exercises.

Isotometric and Isotonic Exercises

Isometric means “same length”, and with strengthening these exercises consist of resisted muscular engagement without active movement. These exercises are utilized early in the rehab program due to decreased demand and likelihood of causing pain.

Isotonic exercises contract the muscle contracts against a constant resistance, such as lifting a dumbbell or squatting. These are a progression past isometrics, and more closely emulate activities of daily living. These likely consist of the majority of strengthening completed in an impingement plan of care.

  • Pinches/blade squeezes activate upper back muscles while not placing much strain on the shoulder. Passive stretching is often best in the initial stages, and in the straight/sagittal plane (flexion) in front of the body. As you progress, you’ll move outwards towards the side of your body, but be limited in your ROM in that plane.
  • In general, overhead weight training movements get discouraged due to increased likelihood of impingement. Sports with overhead movements (swimming, baseball, volleyball) can irritate due to the repeated overhead and external rotation movements.

Steroid injection and impingement syndrome

Since the pain associated with impingement syndrome is primarily an inflammatory mechanism, a steroid injection (cortico-steroids are known as significant mitigants for inflammation) may help you create a “window” of opportunity to be able to strengthen your shoulder with physical therapy.

Shoulder impingement doesn’t have to last a lifetime

If treated appropriately, with strength and ROM improvements in therapy, patients can correct biomechanical faults which allow for a decrease in symptoms. After being educated during therapy, portions of your Home Exercise Plan (HEP) will contain exercises you need to maintain outside of therapy. We work to improve postural awareness and positioning. Also, you’ll learn new strategies of lifting to protect your shoulder.

Advantages of using a licensed physical therapist

Licensed physical therapists, who now receive a clinical doctorate degree in physical therapy, specialize in identifying abnormal movement patterns and understanding what may be weak, inactive, overactive or limited in mobility. Therapists receive intensive schooling regarding diagnostic testing. This helps diagnose impingement on par with expensive medical imaging. In turn, this could save the patient medical costs due to not receiving an MRI initially.

Suffering from shoulder pain and think it might impingement? Schedule an appointment today with one of our licensed therapists and get some answers.