Subacromial shoulder pain
Ross Hauser, MD, Caring Medical Regenerative Medicine Clinics, Fort Myers, Florida
Danielle R. Steilen-Matias, MMS, PA-C, Caring Medical Regenerative Medicine Clinics, Oak Park, Illinois
David Woznica, MD, Caring Medical Regenerative Medicine Clinics, Oak Park, Illinois
“Swimmer’s shoulder” and shoulder pain, in search of a diagnosis
If you are reading this article you are likely a parent of an adolescent age swimmer or a competitive swimmer yourself. If it is you, you have a lot of pain in the front of your shoulder towards the outside. You may also have a lot of instability or looseness in your shoulder or you may feel that your shoulder is trying to lock itself up. Many times this occurs with an “on and off” frequency of looseness and tightness. You may also feel like you are losing muscle strength even to the point of dropping things out of your hand.
The situation is getting progressively worse, not better. For one thing, you are not swimming or your training has been significantly altered in an attempt “just to keep you in the water.” For the athlete, this leads to clear frustration and returning visits to clinicians who are trying to help, but are not getting anywhere.
The difficulties in understanding subacromial shoulder pain or “swimmer’s shoulder” treatment
The difficulties in understanding subacromial shoulder pain or “swimmer’s shoulder,” is described by doctors from the Department of Orthopedics, Brigham and Women’s Hospital and Tufts University School of Medicine writing in The Journal of the American Academy of Orthopaedic Surgeons:1
Swimmer’s shoulder is a broad term often used to diagnose shoulder injury in swimmers. However, research has shed light on several specific shoulder injuries that often are incurred by the competitive swimmer.
- Hyperlaxity (Excessive movement in the shoulder causing unnatural wear and tear and friction on the soft tissue – this is creating unchecked inflammation and shoulder erosion through tissue degeneration).
- Scapular dyskinesis (Scapular dyskinesis or SICK scapula syndrome) is considered an overuse injury in which there is abnormal movement and resting location of the scapula (the shoulder blades or “wing” bones.” In other words, the scapula is not where it is supposed to be and it is causing unnatural wear and tear and friction on the soft tissue).
- Subacromial impingement syndrome – the rotator cuff tendons and shoulder bursae are trapped under the acromion process, the bone of the “high point,” of the shoulder and this is causing unnatural wear and tear and friction on the soft tissue. Doctors may also look at os acromiale, (Doctors in France describe os acromiale as a failure of fusion of the acromial process, it is in a hypermobile state. It is usually asymptomatic and discovered by chance. When it is painful a differential diagnosis must be made in relation to the subacromial impingement syndrome.2
- Shoulder labral damage,
- Suprascapular nerve entrapment. The suprascapular nerve is responsible for the innervation (the supplying energy and messages) to the supraspinatus and infraspinatus muscles that attach to the scapula.
- Glenohumeral rotational imbalances. A disruption of the natural range of motion of the shoulder.
The researchers of this study conclude: “An understanding of the mechanics of the swim stroke, in combination with the complex static and dynamic properties of the shoulder, is essential to the comprehension and identification of the painful swimmer’s shoulder. It is important for the athlete, coach, and clinician to be aware of the discerning characteristics among these different injuries to ensure a proper diagnosis and treatment plan to aid the swimmer in his or her return to competition.”
- In other words, the clinician needs to investigate deeply the problems of the swimmer’s shoulder to enact the best and quickest treatments.
If you are reading this article, it is likely that you have been on a course of conservative treatments for some time and you have reached a new degree of urgency in finding your solution.
Rest, Ice, Anti-inflammatories, and Cortisone have not helped generations of American swimmers
Swimmer’s shoulder has been a problem for a long time. In 1980 Famed orthopedic surgeon Frank Jobe, the same surgeon who invented the Tommy John Surgery, joined with Dr. Allen Richardson and Dr. H. Royer Collins from the National Athletic Health Institute, Inglewood, California to write in the American Journal of Sports Medicine (3) of the problem of swimmer’s shoulder in America’s best competitive swimmers:
- Shoulder pain is the most common orthopedic problem in competitive swimming. In a group of 137 of this country’s best swimmers, 58 had had symptoms of “swimmer’s shoulder.”
- Population characteristics of this group indicated that symptoms increased with the caliber of the athlete, were slightly more common in men, and were related to sprint rather than distance swimming. The use of hand-paddle training exacerbated symptoms, which were more common during the early and middle season.
- Treatment included stretching, rest, ice therapy, oral anti-inflammatory agents, judicious use of injectable steroids, and surgery as a last resort.
Thirty-five years later in 2015, these treatment options did not seem to have helped nearly two generations of swimmers.
Writing in the American Journal of Sports Medicine, (4)doctors from the Department of Orthopedic Surgery, Scripps Clinic, La Jolla, California wrote of applying The Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Score to define functional and performance measures of the upper extremity in overhead athletes. To date, no study has investigated the baseline functional scores for swimmers actively competing in the sport. What the doctors were doing was to use The Kerlan-Jobe Orthopedic Clinic Shoulder and Elbow Score to come up with baseline measurements. They were surprised by what they found:
- Baseline scores for swimmers, which were lower than expected, were lower than baseline scores seen in studies of other overhead sports athletes.
- The data corroborate previous studies identifying swimmers as having a high level of shoulder trouble.
- Further research is indicated for improving shoulder symptoms and performance in competitive swimmers.
In 2010 Klaus Bak of the Parken’s Private Hospital, Copenhagen, Denmark wrote in the Clinical journal of sport medicine: (5)
- Balanced strength training of the rotator cuff, improvement of core stability, and correction of scapular dysfunction is central in treatment and prevention.
- Technical and training mistakes are still a major cause of shoulder pain
- Imaging modalities (MRI) rarely help clarify the diagnosis, their main role being exclusion of other pathology.
- If nonoperative treatment fails, an arthroscopy with debridement, repair, or reduction of capsular hyperlaxity is indicated.
- The return rate and performance after surgery is low, except in cases where minor glenohumeral instability is predominant.
- Overall, the evidence for clinical presentation and management of swimmer’s shoulder pain is sparse.
When the problem is not inflammation but instability
Our clinics have published numerous studies on the problems of shoulder joint instability and inflammation. Some of this research is summarized below. The simple idea is that instability causes inflammation. If you do not correct the instability you can not correct the inflammation. Anti-inflammatory medications can only make the situation worse in the long run. To treat the problems of the swimmer’s shoulder, in our opinion, the swimmer must treat the problems of instability. This, of course, can be addressed in two ways, surgical and non-surgical treatment. Let’s start exploring.
The surgical option called into question, criticism from surgeons
When discussing surgical options for Swimmer’s shoulder, it is best to bring in surgical opinions. In our clinics, we offer non-surgical regenerative treatments. In many patients we see, surgery can be avoided. Below we will also discuss the scenario when the shoulder is “too far gone,” and surgery will be needed.
The idea that arthroscopic surgery for shoulder impingement was a valueless procedure was put worth in November 2017, when one of the leading medical journals in the world, The Lancet, (6) reported the findings of 51 surgeons operating at 32 hospitals around the United Kingdom.
In this study, 313 patients who had subacromial pain for at least 3 months with intact rotator cuff tendons, were considered eligible for arthroscopic surgery. These same patients had previously completed a non-operative management program that included exercise therapy and at least one steroid injection.
The 313 patients were then divided into three groups:
- Arthroscopic subacromial decompression surgery group (106 patients),
- investigational arthroscopy surgery only (103 patients),
- or no treatment (104 patients)
Here are the results of the researchers:
- Surgical groups had better outcomes for shoulder pain and function compared with no treatment but this difference was not clinically important. (Not enough evidence to warrant surgery).
- Additionally, surgical decompression appeared to offer no extra benefit over arthroscopy only. (The more invasive and complicated surgery offered no further benefit).
- The difference between the surgical groups and no treatment might be the result of, for instance, a placebo effect or postoperative physiotherapy. (The success of the surgery may not have been the surgery itself but rather, the placebo effect).
- The findings question the value of this operation for these indications, and this should be communicated to patients during the shared treatment decision-making process. (Doctors should tell the patient that if they get the more invasive surgery, the less invasive surgery, or no treatment, their outcomes will be about the same).
And finally, in the study recap:
“During the past three decades, clinicians and patients with subacromial shoulder pain have accepted minimally invasive arthroscopic subacromial decompression surgery in the belief that it provides reliable relief of symptoms at low risk of adverse events and complications. However, the findings from our study suggest that surgery might not provide clinically significant benefit over no treatment.”
In an accompanying article in The Lancet, Netherland University researchers Berend W Schreurs and Stephanie L. van der Pas, wrote:
“The findings send a strong message that the burden of proof now rests on those who wish to defend the standpoint that shoulder arthroscopy is more effective than non-surgical interventions. Hopefully, these findings from a well respected shoulder research group will change daily practice. The costs of surgery are high, and although the low occurrence of complications might suggest that the surgery is benign, there is no indication for surgery without possible gain.”(7)
In other words, don’t have a surgery that does not help.
This study was backup in 2018 when, in a landmark study, Finnish researchers showed that arthroscopic surgeries of the shoulder are useless for patients with “shoulder impingement.”
This is the simple conclusion of this groundbreaking study that appeared in the British Medical Journal, July 19, 2018 (8)
“The results of this randomized, placebo surgery controlled trial show that arthroscopic subacromial decompression provides no clinically relevant benefit over diagnostic arthroscopy in patients with shoulder impingement syndrome. The findings do not support the current practice of performing subacromial decompression in patients with shoulder impingement syndrome.”
There are times when tearing of the rotator cuff tendons are so catastrophic, because preventive treatment was delayed or anti-inflammatory treatments went on too long, that the swimmer must make a decision on whether to go through with more invasive surgery, to address the rotator cuff or to address the options surrounding a bursectomy, the surgical removal of the shoulder bursa (bursae).
- They are going to continue swimming
- How long can they allow themselves to recover in terms of months perhaps years?
- Is surgery likely to be of help?
- Will the surgery leave you with impaired strength and make itself useless to you for the goal of returning to swimming?
Doctors at the Department of Orthopaedic Surgery, University of Kentucky School of Medicine wrote this StatPearls,(9) part of the National Center for Biotechnology Information internet library.
- “Surgery is appropriate for structural pathologies (damage). An athlete may elect symptomatic management rather than surgery so that he or she may continue competing until the pain begins to interfere with daily life.
- For swimmers with persistent multidirectional instability, a capsular plication (this is a radiofrequency (RF) procedure that hopes to tighten soft tissue in the shoulder through contraction) or inferior capsular shift procedure (this is an open surgical procedure where the bottom part of the shoulder’s soft tissue is pulled up and the top part is pulled down and secured.)
- Athletes should be aware, however, that training volumes may need to be reduced permanently to avoid pain.
- A subacromial exploration and removal of the hypertrophied, inflamed, and scarred tissue (thereby maintaining the structural integrity of the shoulder) is an option for athletes who obtain only limited relief from physical therapy. For swimmers with a labral tear in whom nonsurgical treatment has failed, the next treatment option is labral debridement or repair.”
Non-surgical treatment addressing shoulder instability, wear and tear and inflammation in the swimmer
At our clinics, we have provided more than 25 years of service to patients seeking non-surgical options to get them back to their sport. In this section we will show our research and research of other clinicians in offering non-surgical solutions to “Swimmer’s Shoulder.”
Part of the reason for arthroscopic surgical failure is that it does not properly address that problems of hypermobility and shoulder instability. Possibly, because you are removing tissue in the shoulder during surgical procedures, the problem of instability becomes worse.
The problem of how to deal with this instability was reflected in a study from the Hospital for Special Surgery, published 2018 in the journal Current reviews in musculoskeletal medicine.(9)
“Swimmers may develop increased shoulder laxity over time due to repetitive use. Such excessive laxity can decrease passive shoulder stability and lead to rotator cuff muscle overload, fatigue, and subsequent injury in order to properly control the translation of the humeral head (the movement of the shoulder).
- Generalized laxity can be present up to 62% of swimmers, while a moderate degree of multi-directional instability can be present in the majority.
- Laxity in swimmers can be due to a combination of underlying inherent anatomical factors as well as from repetitive overhead activity.
- The role of excessive laxity and muscle imbalance are crucial in the swimmer’s shoulder and should be well understood since they are the primary target of the training and rehabilitation program.”
A look at physical therapy
Like the world of regenerative medicine, physical therapists seek to prevent further destruction of the swimmer’s shoulder with a rehabilitation plan.
A review published in the North American journal of sports physical therapy, (10) gives a good outline of the challenges facing physical therapists in helping the patient with swimmer’s shoulder.
“Physical therapists involved in the treatment of competitive swimmers should focus on prevention and early treatment, addressing the impairments associated with this condition, and analyzing training methods and stroke mechanics.”
“Swimmers shoulder is a condition that may be prevented with adequate preseason screening that can identify impairments and training errors that may lead to symptoms. If a swimmer does become symptomatic during the season, the physical therapist should identify the most likely impairments or training errors and rule out any significant tissue pathology that would warrant a referral to an orthopedic surgeon. A comprehensive rehabilitation program usually includes strengthening of the rotator cuff and scapular stabilizers, stretching anterior chest musculature that may be shortened, and implementing activity modification so the athlete can still participate in the sport.”
A look at Prolotherapy and Platelet Rich Plasma Therapy for Shoulder Instability and Pain
At our clinics we frequently work with physical therapists who are treating athletes. For physical therapy to achieve maximum benefit in the patient with Swimmer’s Shoulder, the shoulder capsule itself has to be capable of providing muscle resistance. If the tendons of the rotator cuff and the ligaments that hold the bone structure of the shoulder are compromised, as seen by excessive shoulder instability and hypermobility, including partial dislocation, the shoulder may not be able to provide the resistance needed for maximum gain.
When it comes to seeking non-surgical options in the treatment of difficult to treat or chronic shoulder pain, patients frequently find themselves researching our injection treatments of Comprehensive Prolotherapy incorporating various treatments to include Platelet Rich Plasma Therapy, and Dextrose Prolotherapy.
These injection techniques stimulate the repair of injured tissue and have been cited in the research as curative for chronic pain.
Platelet Rich Plasma Therapy, is an injection treatment that re-introduces your own concentrated blood platelets into areas of chronic joint and spine deterioration, more commonly referred to as PRP. There are many orthopedic surgeons now offering this treatment.
For the competitive swimmer, it should be noted that there are many ways to administer this treatment. At our clinics, we utilize a more aggressive approach as demonstrated in the video.
No standard way to offer PRP treatment for shoulder impingement causes controversy
The medical literature is filled with studies suggesting the PRP treatment is effective for a myriad of shoulder problems. PRP works because it addresses damaged tendons and repairs them in a non-surgical way by rebuilding tissue on a cellular level. We are going to stress throughout this segment of our article, our more than 25 years of experience in offering regenerative medicine techniques, such as PRP and will call into question doctors and clinicians who offer this treatment after attending a weekend workshop and then announce to their patients that this treatment does not seem to be effective. We will also bring attention to “failed PRP” treatments that consists of a “single injection.”
In a new study from 2018, Doctors at The Orthopedic-Traumatology Department of Prostějov Hospital in the Czech Republic published these observations.(11)
This study aimed to explore the effects of new therapeutic procedures in patients with shoulder impingement syndrome. The primary goal of the study was to confirm the hypothesis that the application of the platelet-rich plasma (PRP) in patients with shoulder impingement syndrome will have a positive effect on both the subjective and objective evaluation of their condition.
The secondary goal was to compare the effect achieved by a series of 3 PRP injections and that achieved by treating the impingement syndrome with a standard single depot corticosteroid injection.
The PRP injection was given at 6 weeks, 3 months and 6 months after the administration of the injection.
CONCLUSION of Study: “Based on the results of our study, the hypothesis can be accepted that the concentrate of platelet-rich plasma administered through a series of 3 injections applied in the subacromial space in patients with shoulder impingement syndrome has positive effects on the daily activities of patients as well as on the objective evaluation via the selected scoring systems.”
Research like that above, where more than one injection is given counters research that measures PRP’s ability to help swimmer’s shoulder with only one or two injections.
Let’s illustrate this is a recent published study. In the May 2017 issue of the Orthopaedic journal of sports medicine, doctors compare PRP Injections to exercise as non-surgical treatments of subacromial shoulder pain. Here are the learning points of this research.
- The doctors went into the study with an expectation that Platelet-rich plasma (PRP) would be an effective method in treating subacromial impingement.
- This was a single-blinded randomized clinical trial with 1-, 3-, and 6-month follow-up.
- Sixty-two patients were randomly placed into 2 groups, receiving either PRP or exercise therapy.
- The outcome parameters were pain, shoulder range of motion (ROM), muscle force, functionality, and magnetic resonance imaging findings.
- Results: Both treatment options significantly reduced pain and increased shoulder ROM compared with baseline measurements.
- Both treatments also significantly improved functionality.
- Both PRP injection and exercise therapy were effective in reducing pain and disability in patients with subacromial shoulder pain, with exercise therapy proving more effective.(12)
Two injections do not make comprehensive treatment
- The study above indicated that two treatments of PRP worked very well, but over the same course of time exercise worked a little better. What if the subjects of this study received a more aggressive PRP program, what if the more aggressive PRP was combined with physical therapy? Would not the swimmer get back to the pool that much faster? What if we now add a third component? The dextrose Prolotherapy.
PRP is best used in conjunction with Prolotherapy
In our clinics we have found that when we use PRP to strengthen tendons within the shoulder capsule, we can help those tendons heal and strengthen by using dextrose Prolotherapy to strengthen the ligaments that surround the shoulder capsule. This process is again, described in the video above.
Prolotherapy on its own has been shown to be an effective treatment for shoulder repair.
In 2013, Medical University research teams in Turkey presented their findings on “The Effects of Prolotherapy in Patients With Subacromial Impingement Syndrome.” (13) These are the learning points of their research:
- Recent treatments for subacromial impingement syndrome are palliative (in other words treating the symptom and not the cause). Dextrose injection, Prolotherapy, has emerged as a treatment option for chronic situations such as shoulder tendinitis and shoulder bursitis.
- The aim of the study is to investigate the effects of dextrose injection in patients with chronic shoulder pain caused by subacromial impingement syndrome.
In this single-center, randomized placebo controlled, single blind, prospective study, 80 patients with chronic subacromial impingement syndrome who met the study criteria received two dextrose injections in the affected shoulder at two weeks intervals.
The patients were randomly assigned into two therapy groups, either dextrose or other control (lidocaine) groups.
The injections were repeated two times with two weeks between injections.
- Clinical assessments included measurement of:
- range of motion (ROM),
- pain assessment
- shoulder functions and daily living activities
- Magnetic resonance imaging (MRI) evaluation was conducted before the first injection and compared with MRI’s taken again on the third month following the second injection.
Results: The study demonstrated significant improvements in function and pain in both injection groups. Shoulder flexion, abduction, internal and external rotations showed significant improvements in both groups in the first 3 months. While the range of shoulder flexion did not improve in the control group during the last three months, this range of motion continued to improve significantly in the Prolotherapy treatment group over the same period.
Again we want to point out here that the patients received benefit from only two injections, please watch the video for a comparison of our more aggressive treatment.
In our research, published in Clinical medicine insights. Arthritis and musculoskeletal disorders, (13) Ross Hauser, MD and Danielle R. Steilen-Matias, MMS, PA-C contributed to findings suggesting Dextrose Prolotherapy has been able to reduce pain and disability of traumatic and nontraumatic rotator cuff conditions.
- Research revealed that treatment of moderate to severe rotator cuff tendinopathy due to injury with injections of hypertonic dextrose on painful entheses (the ligament and tendon attachments to the bone) resulted in superior long-term pain improvement and patient satisfaction compared with blinded saline injection over painful entheses, with intermediate results for entheses injection with saline.
- In a retrospective case–control study, dextrose Prolotherapy improved in pain, disability, isometric strength, and shoulder active range of motion in patients with refractory chronic non-traumatic rotator cuff disease.
In our research published in The Open Rehabilitation Journal (14) our research team found that lesions of the glenoid labrum are a common cause of shoulder instability and a frequent finding in patients with shoulder pain. Management of these patients typically involves an attempt to avoid surgery through conservative treatment. However, there is currently a dearth of conservative options that promote labral healing.
- Regenerative injection therapies, including prolotherapy, have shown promise in the treatment of several musculoskeletal disorders, but have not previously been applied to glenoid labral tear.
- Here we review several important aspects of these lesions and present an initial case series of 33 patients with labral tear that were treated in our clinic with intra-articular injections of hypertonic dextrose.
- Patient-reported assessments were collected by questionnaire at a mean follow-up time of 16 months.
- Treated patients reported highly significant improvements with respect to pain, stiffness, range of motion, crunching, exercise and need for medication.
- All 31 patients who reported pain at baseline experienced pain relief, and all 31 who reported exercise impairment at baseline reported improved exercise capability. Patients reported complete relief of 69% of recorded symptoms. One patient reported worsening of some symptoms. Prolotherapy for glenoid labral tear appears to be a safe procedure that merits further investigation.
More of our research surrounding problems of the shoulder:
- Rotator Cuff Tear Alternatives To Surgery In this article we discuss the problem of initial rotator cuff tear and re-tears caused by non-healing of the rotator cuff tendons and non-surgical options.
- Rotator Cuff Tendinopathy – Tendinitis – Tendinosis In this article we discusses diagnosis and treatment of Rotator Cuff Tendinopathy. Treatments include conservative care and the emerging science of biological augmentation (Platelet Rich Plasma Therapy and Stem Cell Therapy).
- Slap Lesion Tears New research explored the many surgical options in the treatment of SLAP lesions, however, while there are many options, unfortunately the success rates of these surgeries are being called into question.
- Glenoid Labral Tears A discussion of injury to the glenoid labrum results in instability, dislocation and pain.
- Chronic Shoulder Dislocation and Instability In this article we will discuss that the main cause of chronic shoulder dislocations are chronic shoulder dislocations. This is not a play on words, treat and cure the chronic shoulder dislocation and you prevent future dislocations.
If you have questions about subacromial shoulder pain and swimmer’s shoulder treatment, Get help and information from our Caring Medical staff
1. Matzkin E, Suslavich K, Wes D. Swimmer’s shoulder: Painful shoulder in the competitive swimmer. Journal of the American Academy of Orthopaedic Surgeons. 2016 Aug 1;24(8):527-36. [Google Scholar]
2. Barbier O, Block D, Dezaly C, Sirveaux F, Mole D. Os acromiale, a cause of shoulder pain, not to be overlooked. Orthopaedics & Traumatology: Surgery & Research. 2013 Jun 30;99(4):465-72 [Google Scholar]
3. Richardson AB, Jobe FW, Collins HR. The shoulder in competitive swimming. The American Journal of Sports Medicine. 1980 Jun;8(3):159-63. [Google Scholar]
4. Wymore L, Fronek J. Shoulder functional performance status of national collegiate athletic association swimmers: baseline Kerlan-Jobe orthopedic clinic scores. The American journal of sports medicine. 2015 Jun;43(6):1513-7. [Google Scholar]
5. Bak K. The practical management of swimmer’s painful shoulder: etiology, diagnosis, and treatment. Clinical Journal of Sport Medicine. 2010 Sep 1;20(5):386-90. [Google Scholar]
6 Beard DJ, Rees JL, Cook JA, Rombach I, Cooper C, Merritt N, Shirkey BA, Donovan JL, Gwilym S, Savulescu J, Moser J. Arthroscopic subacromial decompression for subacromial shoulder pain (CSAW): a multicentre, pragmatic, parallel group, placebo-controlled, three-group, randomised surgical trial. The Lancet. 2017 Nov 20. [Google Scholar]
7 Schreurs BW, van der Pas SL. No benefit of arthroscopy in subacromial shoulder pain. The Lancet. 2017 Nov 20. [Google Scholar]
8 Paavola M, Malmivaara A, Taimela S, Kanto K, Inkinen J, Kalske J, Sinisaari I, Savolainen V, Ranstam J, Järvinen TL. Subacromial decompression versus diagnostic arthroscopy for shoulder impingement: randomised, placebo surgery controlled clinical trial. bmj. 2018 Jul 19;362:k2860. [Google Scholar]
9 Nickerson, M. and Gossman, W.G., 2017. Shoulder, Swimmer’s. updated November 2018. [Google Scholar]
10 Tovin BJ. Prevention and treatment of swimmer’s shoulder. North American journal of sports physical therapy: NAJSPT. 2006 Nov;1(4):166. [Google Scholar]
11 Šmíd P, Hart R, Komzák M, Paša L, Puskeiler M. Treatment of the Shoulder Impingement Syndrome with PRP Injection. Acta chirurgiae orthopaedicae et traumatologiae Cechoslovaca. 2018;85(4):261-5. [Google Scholar]
12 Nejati P, Ghahremaninia A, Naderi F, Gharibzadeh S, Mazaherinezhad A. Treatment of Subacromial Impingement Syndrome: Platelet-Rich Plasma or Exercise Therapy? A Randomized Controlled Trial. Orthopaedic Journal of Sports Medicine. 2017 May 19;5(5):2325967117702366. [Google Scholar]
13 Hauser RA, Lackner JB, Steilen-Matias D, Harris DK. A systematic review of dextrose prolotherapy for chronic musculoskeletal pain. Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders. 2016 Jan;9:CMAMD-S39160. [Google Scholar]
14 Hauser RA, Dolan E, Orlofsky A. Prolotherapy: A Non-Invasive Approach to Lesions of the Glenoid Labrum; A Non-Controlled Questionnaire Based Study. The Open Rehabilitation Journal. 2013 Dec 27;6(1). [Google Scholar]