Orthopaedic Surgery - Subacromial Injection

Basics

Subacromial injection is a commonly used office-based procedure designed to:

Reduce pain and inflammation

within the:

Subacromial space.

By improving pain and shoulder motion, the injection may allow patients to participate more effectively in:

Physical therapy

and regain:

Strength and function.

Role of Exercise

Injection therapy is generally more effective when combined with:

Exercise-based rehabilitation.

Physical therapy helps address:

Rotator cuff weakness

Scapular dyskinesis

and limitations in:

Range of motion.

Common Uses

Subacromial injection is commonly used for:

Rotator cuff tendinopathy

Calcific tendinopathy

Subacromial bursitis

Subacromial impingement

and selected cases of:

Adhesive capsulitis.

Diagnostic and Therapeutic Uses

The injection may be used as:

A therapeutic treatment

or

A diagnostic test.

Therapeutic Injection

Therapeutic injections usually include:

Corticosteroid

with or without:

Local anesthetic.

The primary goal is reduction of:

Pain and inflammation.

Diagnostic Injection

A local anesthetic such as:

Lidocaine

may be used to determine whether the patient’s symptoms originate from the:

Subacromial space.

Marked short-term pain relief after injection supports the diagnosis of a:

Subacromial pain generator.

Emerging Injectates

Other agents such as:

Platelet-rich plasma

and

Hyaluronic acid

have been investigated for shoulder disorders.

Their role in routine subacromial treatment remains:

Less established than corticosteroid injection.

Multimodal Treatment

Subacromial injection is usually used after or together with:

Physical therapy

NSAIDs

Activity modification

and other:

Nonoperative measures.

Injection Approaches

Common approaches include:

Posterior

Lateral

and

Anterior approaches.

Posterior and lateral approaches are particularly common and generally demonstrate:

Similar clinical effectiveness.

Ultrasound Guidance

Ultrasound may be used to improve confidence that the needle enters the:

Subacromial-subdeltoid bursa.

Landmark-guided injections can also be effective when performed by an:

Experienced clinician.

Indications

Potential indications include:

Subacromial bursitis

Rotator cuff tendinopathy

Partial rotator cuff tears

Subacromial impingement

Painful os acromiale

and selected cases of:

Calcific tendinopathy.

Adhesive Capsulitis

Subacromial injection may occasionally be used in patients with:

Adhesive capsulitis.

However, because the primary pathology is within the:

Glenohumeral capsule

an:

Intra-articular glenohumeral injection

may be more directly beneficial.

Rotator Cuff Tears

Subacromial injection can reduce associated:

Bursal inflammation

and

Pain.

However, it does not repair the underlying:

Tendon tear.

Treatment

General Measures

Nonoperative treatment is usually attempted before surgery.

A typical program includes:

Activity modification

Physical therapy

NSAIDs

and, when appropriate,

Subacromial corticosteroid injection.

Physical Therapy Focus

Rehabilitation commonly emphasizes:

Periscapular stabilization

Rotator cuff strengthening

and restoration of:

Shoulder motion.

Diagnostic Value of Injection

The patient’s shoulder should ideally be examined:

Before

and

After injection.

This helps determine which symptoms improve after the anesthetic takes effect.

Persistent Weakness After Injection

If pain improves but:

Objective weakness persists

a structural lesion such as a:

Rotator cuff tear

should be considered.

Inflammation

Inflammation after tissue injury involves:

Increased blood flow

Capillary permeability

and recruitment of:

Inflammatory cells.

This contributes to:

Edema

Pain

and local tissue irritation.

Corticosteroid Mechanism

Corticosteroids suppress multiple components of the:

Inflammatory response.

They reduce:

Capillary dilation

Inflammatory-cell recruitment

and release of various:

Inflammatory mediators and enzymes.

Common Corticosteroids

Agents commonly used include:

Methylprednisolone acetate

Triamcinolone acetonide

and

Dexamethasone.

Local Anesthetics

Common local anesthetics include:

Lidocaine

and

Bupivacaine.

These provide:

Short-term analgesia

and can assist with the:

Diagnostic response.

Physical Therapy

Injection should usually serve as an adjunct to:

Rehabilitation

rather than a replacement for it.

Combining injection with therapy may improve:

Pain

Motion

and

Functional recovery.

Medication

A variety of corticosteroid and local anesthetic combinations may be used.

Choice depends on:

Clinician preference

Patient factors

and institutional:

Practice.

Procedure

Subacromial injection should be performed using:

Sterile technique.

Required Equipment

Typical equipment includes:

Sterile gloves

Skin antiseptic

Syringe

Appropriate-gauge needle

Corticosteroid

and optionally:

Local anesthetic.

Skin Preparation

The skin may be prepared with agents such as:

Chlorhexidine

Povidone-iodine

or

Alcohol.

Consent

Before the procedure, informed consent should address:

Expected benefits

Alternatives

and potential:

Risks and complications.

Local Skin Anesthesia

A cooling spray or small amount of:

Local anesthetic

may be used before the main injection.

When local anesthetic is infiltrated into the skin, a small wheal can be raised with a:

Fine needle.

Patient Position

The patient is usually:

Seated upright

with the arm relaxed and hanging at the:

Side.

This position facilitates access to the:

Subacromial space.

Landmark Identification

The border of the:

Acromion

is palpated.

For posterior or lateral injections, the needle is introduced just:

Inferior to the acromial margin.

Posterior Approach

In the posterior approach, the needle is directed into the:

Subacromial space

from the posterolateral aspect of the shoulder.

Lateral Approach

In the lateral approach, the needle is passed beneath the:

Lateral edge of the acromion

toward the:

Subacromial bursa.

Ultrasound-Guided Technique

Ultrasound can visualize:

Needle position

and

Bursal distention

during injection.

It may be particularly useful in patients with:

Altered anatomy

or after an unsuccessful landmark-guided:

Procedure.

Aspiration Before Injection

Before injecting, the clinician should:

Aspirate gently

to reduce the chance of injecting directly into a:

Blood vessel.

Injection Resistance

A correctly positioned needle should generally encounter:

Minimal resistance.

If marked resistance is felt, the needle should be:

Withdrawn slightly and repositioned.

Injection Volume

Historical techniques commonly use a combined injectate volume of approximately:

6–10 mL

including:

Local anesthetic and corticosteroid.

Actual volume varies according to the:

Medication and technique.

Completion

After injection, the needle is removed and the site is covered with a:

Small dressing.

Postinjection Examination

The shoulder may be reassessed approximately:

5–10 minutes later

once the local anesthetic has taken effect.

Interpretation of Immediate Response

Improved:

Pain

Range of motion

or

Strength limited previously by pain

supports a:

Subacromial pain source.

Persistent Weakness

Persistent true weakness despite adequate analgesia may suggest:

Rotator cuff tearing

or another:

Neuromuscular abnormality.

Follow-Up

The patient’s subsequent response should be assessed over:

Days to weeks.

Pain Journal

Patients may record:

Pain intensity

Duration of relief

and improvement in:

Activity and sleep

after the injection.

Prognosis

Outcome depends on the:

Underlying diagnosis.

Subacromial Impingement

For subacromial pain syndromes, corticosteroid injection alone or combined with:

Physical therapy

can provide substantial improvement in many patients.

Benefits are often greatest for:

Short-term pain relief

and facilitation of:

Rehabilitation.

Long-Term Effect

Long-term outcome is influenced more by:

Underlying pathology

Exercise adherence

and correction of:

Biomechanical factors

than by the injection alone.

Complications

Complications are generally:

Uncommon.

Infection

Iatrogenic infection is rare but potentially serious.

Strict:

Sterile technique

is therefore essential.

Hematoma

Patients taking:

Anticoagulants

or those with a:

Bleeding disorder

may have an increased risk of:

Bruising or hematoma.

Skin Hypopigmentation

Corticosteroid injection may cause localized:

Skin depigmentation

particularly when medication is deposited too:

Superficially.

Subcutaneous Fat Atrophy

Local corticosteroid exposure may also cause:

Subcutaneous fat atrophy

near the injection site.

Tendon Effects

Repeated corticosteroid exposure may adversely affect:

Rotator cuff tendon quality.

Experimental and clinical data suggest possible reduction in:

Tendon strength

and impaired:

Healing potential.

Surgical Considerations

Recent corticosteroid injection may also be relevant when planning:

Rotator cuff repair

or

Shoulder arthroplasty

because timing may influence:

Infection risk

and

Tendon healing.

Hyperglycemia

Corticosteroids may cause a transient rise in:

Blood glucose.

Patients with:

Diabetes mellitus

should be warned about this possibility and may require closer:

Glucose monitoring.

Contraindications and Precautions

Local Skin Infection

Injection should not be performed through an area of:

Cellulitis

Open wound

or

Skin breakdown.

Unstable Coagulopathy

Significant uncontrolled bleeding abnormalities are a:

Contraindication

until appropriately:

Corrected.

Diabetes

Injection should be used cautiously in patients with:

Diabetes

because of the risk of:

Transient hyperglycemia.

Medication adjustment may occasionally be necessary.

Immunocompromised Patients

Extra caution is appropriate in:

Immunocompromised patients

because of potentially increased:

Infection risk.

Shoulder Arthroplasty

Patients with a:

Shoulder prosthesis

should generally not undergo periarticular injection without consultation with the treating:

Orthopaedic surgeon.

Repeated Injections

Repeated corticosteroid injections are:

Controversial.

Potential concerns include:

Tendon degeneration

Reduced bone quality

and possibly increased risk of:

Infection or impaired surgical healing.

Frequency

There is no universally appropriate fixed number of:

Repeat injections.

The decision should be individualized according to:

Diagnosis

Response

Comorbidities

and future:

Surgical plans.

Patient Monitoring

Immediate monitoring should assess:

Pain relief

Strength

and

Range of motion.

Short-Term Monitoring

Patients should also watch for:

Increasing redness

Fever

Severe swelling

or escalating:

Pain

which may suggest:

Infection or another complication.

Diabetic Monitoring

Patients with diabetes should monitor:

Blood glucose

more closely for a short period after:

Corticosteroid injection.

Key Principle

Subacromial injection is a diagnostic and therapeutic procedure used primarily for painful conditions arising from the subacromial space, including:

Bursitis, rotator cuff tendinopathy, partial cuff tears, and impingement-type pain.

Local anesthetic can help determine whether symptoms originate from the:

Subacromial space, while corticosteroid may provide:

Short-term reduction in pain and inflammation.

The greatest benefit usually occurs when injection is combined with:

Physical therapy, rotator cuff and scapular strengthening, activity modification, and restoration of motion.

Important precautions include:

Diabetes, immunosuppression, bleeding risk, skin infection, prosthetic shoulder joints, and repeated corticosteroid exposure.