Shoulder pain with overhead movement is commonly labeled “shoulder impingement.” Today, many clinicians use the broader term rotator cuff–related shoulder pain or subacromial pain syndrome because pain rarely comes from one structure being mechanically pinched in one simple way. The rotator cuff tendons, subacromial bursa, shoulder capsule, labrum, ligaments, shoulder blade mechanics, muscle strength, workload, and sometimes the cervical spine can all influence symptoms.

At Caring Medical, we evaluate the whole shoulder rather than treating an MRI finding alone. In some patients, painful tendon overload occurs in a shoulder that is also not being controlled well because of ligament laxity or subtle joint instability. This is one reason a patient may improve temporarily with rest, therapy, or a corticosteroid injection yet experience recurrent pain when returning to work, weight training, throwing, swimming, or other overhead activity.

Prolotherapy is one possible nonsurgical treatment for selected patients with chronic tendon- or ligament-related shoulder pain. It is not appropriate for every painful shoulder, and the current evidence does not establish it as universally superior to exercise, corticosteroid injection, or other conservative treatments. The most accurate interpretation is that some trials report meaningful improvement, while systematic reviews reach conflicting conclusions because protocols, injection targets, comparison treatments, and patient populations differ.

 

What is shoulder impingement syndrome?

The shoulder has a remarkable range of motion, but that mobility comes with a need for precise muscular and ligamentous control. The ball of the upper arm—the humeral head—must remain centered in the shallow glenoid socket while the arm moves. The rotator cuff muscles and tendons help center the joint, while the labrum, capsule, and ligaments provide passive stability.

The term external impingement traditionally describes irritation of the rotator cuff tendons or subacromial bursa beneath the acromion, the bony roof of the shoulder. Internal impingement describes contact between the undersurface of the rotator cuff and the back of the glenoid, often in overhead athletes. In practice, pain may reflect a combination of tendon degeneration, bursitis, altered shoulder-blade motion, weakness, workload errors, and instability rather than a single “pinching” event.

Common symptoms include:

• Pain when raising the arm, especially through a painful arc
• Pain with reaching overhead or behind the back
• Night pain, particularly when lying on the affected shoulder
• Weakness or loss of endurance
• Clicking, catching, or a sense that the shoulder is slipping
• Difficulty throwing, serving, swimming, lifting, or working overhead

Why the diagnosis requires more than one impingement test

No single maneuver or MRI finding can explain every case. A careful evaluation considers the history, pain pattern, range of motion, strength, scapular mechanics, tenderness, instability signs, neck examination, and the demands placed on the shoulder.

Imaging can be useful when the diagnosis is uncertain, symptoms are severe, trauma occurred, substantial weakness suggests a tear, or treatment has failed. Musculoskeletal ultrasound can dynamically assess the rotator cuff and bursa and can help guide an injection when appropriate. MRI may identify a rotator cuff tear, labral injury, arthritis, or other structural abnormality. Imaging must still be interpreted alongside the examination because structural changes can exist without being the primary pain generator.

Important alternative diagnoses include adhesive capsulitis, full-thickness rotator cuff tear, calcific tendinopathy, glenohumeral or acromioclavicular arthritis, biceps tendon disease, labral injury, cervical radiculopathy, suprascapular neuropathy, fracture, infection, and—in uncommon cases—tumor. Sudden inability to lift the arm after trauma, visible deformity, fever, a hot or markedly swollen joint, progressive neurologic weakness, or chest pain requires prompt medical assessment.

Conservative care

Activity modification can reduce repeated aggravation without completely immobilizing the shoulder. Rehabilitation commonly addresses rotator cuff capacity, scapular control, thoracic mobility, gradual loading, and the specific movement demands of the patient’s work or sport. A systematic review of clinical practice guidelines found consistent support for patient education, activity modification, and exercise-based rehabilitation in rotator cuff disorders. (1)

Medication may help selected patients manage pain while they rehabilitate, but risks and contraindications must be considered. Corticosteroid injections can provide short-term relief for some patients; they should not be described simply as harmful or as only “masking” pain. At the same time, repeated injections require caution, particularly when tendon quality is already poor. A 2025 network meta-analysis of subacromial injection trials found that no evaluated injection maintained a pain-relieving advantage beyond three months, although some treatments improved function at later follow-up. (2)

Surgery may be appropriate for acute traumatic tears, substantial loss of function, certain unstable lesions, or persistent symptoms after well-conducted nonsurgical care. However, surgery to “create more space” is not automatically required for chronic subacromial pain. In the placebo-controlled CSAW trial, arthroscopic decompression did not provide a clinically important benefit over diagnostic arthroscopy alone. (3) This does not mean that all shoulder surgery is ineffective; it means the indication and the structural problem must be defined carefully.

Shoulder instability

At Caring Medical, we commonly evaluate whether excessive translation of the humeral head or poor joint control is repeatedly overloading the rotator cuff. Instability can be obvious after a dislocation, but it can also be subtle. Repetitive overhead activity, prior trauma, capsular stretching, labral injury, generalized joint hypermobility, and connective-tissue disorders may contribute.

This is a clinical framework, not proof that instability causes every case of impingement. When instability appears relevant, strengthening and neuromuscular retraining remain important. An injection should not replace a progressive rehabilitation program. We may consider Prolotherapy when pain is chronic, examination findings are compatible with painful ligament or tendon attachments, reasonable conservative care has not restored function, and there is no condition that requires a different treatment.

Microinstability does not require repeated dislocation

In our accompanying video, we explain that a chronically painful shoulder does not have to dislocate or feel as if it is “falling out” to have an instability component. Microinstability refers to smaller-than-normal control problems or excessive translation within the joint. A patient may experience pain, fatigue, clicking, guarding, or loss of confidence in the shoulder without having a dramatic dislocation.

The glenohumeral joint is often compared with a golf ball resting on a tee. The glenoid socket is shallow, allowing tremendous mobility but providing less bony restraint than a deep hip socket. Stability therefore depends heavily on the labrum, capsule, ligaments, rotator cuff, and coordinated movement of the shoulder blade. If these stabilizing structures are injured, stretched, or poorly controlled, the rotator cuff muscles may have to work harder to keep the humeral head centered.

From our clinical perspective, this extra workload may help explain why some patients develop recurring tendon irritation even though they have rested, completed therapy, or temporarily reduced inflammation. This remains a proposed mechanism in an individual patient; it must be supported by that patient’s history and examination rather than assumed from symptoms alone.

How instability could narrow the functional space for the rotator cuff

The supraspinatus tendon and subacromial bursa occupy the space beneath the acromion. This space normally changes as the arm moves. A thickened or painful tendon, an enlarged and irritated bursa, altered shoulder-blade mechanics, or abnormal upward translation of the humeral head may leave these tissues less room during elevation.

The video illustrates a possible sequence:

1. Subtle joint laxity or poor control allows excessive humeral-head movement.
2. The rotator cuff and surrounding muscles work harder to stabilize the joint.
3. Repeated overload may contribute to tendon pain, thickening, or degeneration.
4. The symptomatic tendon and bursa may become more sensitive during overhead motion.
5. Pain causes guarding and compensatory movement, sometimes with the patient hiking or rotating the shoulder blade to avoid the painful arc.

This sequence is not the only explanation for subacromial pain. Tendon biology, age, training load, trauma, metabolic health, occupational demands, and other factors may be equally or more important. It does, however, explain why reducing inflammation alone may not produce durable recovery when a meaningful control or stability problem remains.

The acromioclavicular joint and acromion shape

The video also discusses the acromioclavicular (AC) joint, where the collarbone meets the acromion. Injury or abnormal motion at this smaller joint may contribute to superior shoulder pain and, in selected cases, may affect the tissues below it. Tenderness directly over the AC joint, pain with cross-body motion, and targeted imaging or diagnostic injection can help distinguish an AC-joint problem from rotator cuff–related pain.

Acromion shape is sometimes classified as flat, curved, or hooked. A curved or hooked acromion may reduce the available space for the bursa and rotator cuff in some shoulders, but its presence on an image does not automatically prove that it is causing pain or that bone-removal surgery is necessary. The entire clinical picture—including tendon condition, strength, stability, scapular movement, response to rehabilitation, and functional goals—must be considered.

Why recurring bursitis may be a clue rather than the whole diagnosis

The subacromial bursa is a thin, fluid-containing sac that reduces friction between moving tissues. When irritated, it can become painful and thickened. A corticosteroid injection may reduce bursitis and provide meaningful short-term relief. If the pain repeatedly returns, however, we look for continuing contributors such as excessive workload, incomplete rehabilitation, rotator cuff tendinopathy or tearing, altered scapular mechanics, AC-joint disease, or instability.

In other words, recurrent bursitis may sometimes be the visible reaction to an unresolved mechanical or biological problem. This does not mean that every case of bursitis is caused by instability, nor does failure of one injection establish a need for Prolotherapy.

A clinical example from the video

PA Danielle Matias describes a patient with a curved type II acromion, a labral tear, and clinical shoulder instability. According to the case narrative, the patient underwent several rounds of PRP Prolotherapy directed toward the labral and stability findings, followed by rehabilitation that included carefully introduced hanging exercises. The patient reportedly returned to weight training with greater confidence in the shoulder.

This example illustrates Caring Medical’s treatment rationale, but it is an anecdotal clinical outcome—not a controlled trial and not a promise that another patient will respond similarly. Hanging exercises are not appropriate for every painful or unstable shoulder and should be introduced only when a qualified clinician believes the tissues can tolerate the load.

Related video: Chronic shoulder impingement syndrome and shoulder instability—Has Prolotherapy been tried?

What is dextrose Prolotherapy?

Dextrose Prolotherapy involves injecting a hypertonic dextrose solution at selected painful tendon, ligament, capsular, or joint targets. Dextrose is a form of glucose. The proposed effects include local cell signaling, modulation of pain-related pathways, and stimulation of a healing response. These mechanisms are biologically plausible, but it is too strong to promise that an injection will “rebuild” or permanently repair a tendon or ligament in every patient.

The injection plan matters. Studies have used intratendinous, enthesis, bursal, intra-articular, and periarticular targets with different concentrations and schedules. Therefore, “Prolotherapy” in one trial may not be identical to the comprehensive approach used in another clinic. Ultrasound guidance may improve target visualization, but accurate placement does not guarantee clinical success.

Randomized trials report variable results

A 2016 randomized trial of painful rotator cuff tendinopathy found that dextrose injections at painful tendon-bone attachments produced greater long-term pain improvement than saline injections, but functional outcomes were not clearly different between groups. (4)

In a 2018 trial comparing ultrasound-guided glucose Prolotherapy with corticosteroid injection for supraspinatus tendinopathy, both groups improved. The study did not establish broad superiority of one approach for all outcomes. (5)

A 2022 randomized, double-blind study of chronic supraspinatus tendinosis also reported improvement after hypertonic dextrose injection, while another 2022 comparison found different time-dependent clinical and ultrasound outcomes between dextrose and corticosteroid injections. (6) (7) These studies are encouraging, but they remain relatively small and do not settle the best concentration, target, number of sessions, or comparator.

Recent systematic reviews disagree

A 2024 meta-analysis concluded that hypertonic dextrose Prolotherapy improved pain and function in rotator cuff lesions, but the included studies varied substantially in technique and control treatment. (8)

Two 2025 reviews illustrate the continuing uncertainty. One review of 13 studies involving 936 patients reported statistically significant improvements in pain and function and no major adverse events in the included trials, while noting that more standardized studies and longer follow-up are needed. (9) A separate review of eight studies involving 431 participants found no significant advantage over control treatments for pain or disability, although shoulder abduction improved by about seven degrees. (10)

These conclusions are not necessarily irreconcilable. Reviews may include different studies, pool different control groups, and use different analytical decisions. Statistically significant changes may also be too small to matter to an individual patient. The evidence supports discussing Prolotherapy as an option—not presenting it as proven first-line care or a guaranteed surgery replacement.

Joint hypermobility is an emerging area

A 2024 case series described dextrose Prolotherapy for chronic shoulder pain in patients with joint hypermobility. The report is clinically relevant to the instability model, but a case series has no randomized control group and cannot establish that the injections caused the improvement. (11) Larger controlled trials are needed before applying these findings broadly.

Caring Medical’s published shoulder research

In 2009, Ross Hauser, MD, and Marion Hauser, MS, reported outcomes from 94 patients with chronic shoulder pain treated at an outpatient charity clinic. Most respondents reported improvement in pain and several functional measures. (12)

This study reflects Caring Medical’s clinical experience, but its limitations must be clear: it was retrospective, questionnaire-based, uncontrolled, and published more than 15 years ago. It cannot determine how much improvement came from the procedure rather than natural history, concurrent care, expectations, or selection factors. It is best viewed as hypothesis-generating evidence that helped motivate further study—not as definitive proof of efficacy.

Ross Hauser, MD, and colleagues later published a broader systematic review of dextrose Prolotherapy for chronic musculoskeletal pain. We found supportive evidence across several conditions but also emphasized the need for larger, methodologically rigorous trials. (13)

Prolotherapy compared with corticosteroid and PRP

These procedures should not be treated as interchangeable.

• Corticosteroid injection is anti-inflammatory and may offer relatively rapid short-term pain relief. Repeated exposure near a vulnerable tendon warrants caution.
• Dextrose Prolotherapy is intended to stimulate or modulate a local healing response, but the magnitude and durability of benefit remain uncertain.
• Platelet-rich plasma (PRP) uses concentrated platelets from the patient’s blood. Evidence varies by diagnosis and preparation method. Our discussion of PRP for shoulder impingement reviews that option separately.

The best choice depends on the actual diagnosis, chronicity, tendon integrity, presence of instability, prior care, rehabilitation plan, medical history, cost, and the patient’s goals. A patient with bursitis and an intact tendon may require a different strategy from someone with a partial tear, multidirectional instability, calcific tendinopathy, or pain referred from the neck.

Who may be a candidate for Prolotherapy?

We may consider Prolotherapy when a patient has:

• Chronic rotator cuff–related shoulder pain that has not adequately improved with an appropriate rehabilitation program
• Examination findings suggesting painful tendon attachments, capsular laxity, or ligament-related instability
• Recurrent symptoms when returning to activity despite temporary relief from prior care
• A partial-thickness tendon problem for which immediate surgery is not indicated
• Generalized hypermobility with a clinically unstable, painful shoulder
• Realistic expectations and willingness to participate in rehabilitation

Prolotherapy may be inappropriate or require postponement when there is active infection, uncontrolled bleeding risk, poorly controlled diabetes, allergy to an injectate component, or another condition requiring urgent evaluation. Complete traumatic tears with major weakness, recurrent dislocations with substantial structural damage, fracture, advanced arthritis, and progressive neurologic deficits require diagnosis-specific management and sometimes surgical consultation.

Risks and limitations

Common short-term effects include injection-site pain, soreness, stiffness, bruising, and a temporary symptom flare. Less common but potentially serious complications include infection, bleeding, allergic reaction, nerve injury, vascular injury, or inadvertent injury to nearby structures. Shoulder injections performed near the chest also carry a rare risk of pneumothorax. The clinician should discuss the planned targets, alternatives, expected recovery, and procedure-specific risks before treatment.

Published shoulder trials have generally reported few major adverse events, but small studies cannot exclude uncommon complications. “No major adverse events reported” is not the same as “risk-free.”

Our approach: treat the diagnosis, not the label

At Caring Medical, our goal is to determine why the shoulder remains painful and what is preventing durable recovery. That assessment may include the rotator cuff, bursa, labrum, capsule, ligaments, biceps tendon, acromioclavicular joint, scapular mechanics, neck, and nervous system. When instability appears to be part of the problem, we discuss whether a comprehensive stabilization strategy—including rehabilitation and, in selected cases, Prolotherapy—fits the patient’s findings.

Some patients should continue conservative rehabilitation. Some may benefit from a carefully chosen injection. Others need an orthopedic surgical opinion. Our overview of shoulder pain and discussion of alternatives considered before shoulder decompression surgery provide additional context.

The central message is not that every shoulder impingement is caused by instability or that Prolotherapy replaces established care. It is that persistent shoulder pain deserves a precise diagnosis, a progressive loading plan, and an honest discussion of the strengths and limitations of each treatment option.

Related articles

Shoulder impingement syndrome decompression surgery – What are your alternatives?

Platelet Rich Plasma Therapy and shoulder impingement

References

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Medical disclaimer: This article is for educational purposes and is not a diagnosis or individualized treatment recommendation. Shoulder pain can have many causes. A qualified clinician should evaluate persistent, severe, traumatic, or progressively worsening symptoms and discuss the potential benefits, limitations, alternatives, and risks of any procedure.