A Deep, Throbbing Ache in the Shoulder: Don’t Mistake SLAP Lesion (Superior Labrum Tear) for Frozen Shoulder or Rotator Cuff Tendinitis — Dr. Moriwaki Reviews Intra-Articular Shoulder Pain Aggravated by Overhead Motion and the Role of Stem Cell Conditioned Media Injection into the Shoulder Joint2026.07.25

“A deep, throbbing ache in the back of the shoulder when I swing my arm up hard,” “a catching or clicking sensation when I lift my arm overhead,” “I’ve been treated for frozen shoulder for several months but it’s not getting any better” — pain hiding in the depths of the shoulder like this may in fact be caused by a superior labrum tear (SLAP lesion), an injury of the upper part of the glenoid labrum inside the shoulder joint. It is a condition in which many patients spend a long time under the wrong diagnosis of frozen shoulder or rotator cuff tendinitis, never reaching the appropriate treatment. This article organizes, from the perspective of Dr. Moriwaki of AVAN TOKYO Ginza Regenerative Medicine, what this condition is, how to differentiate it from other shoulder disorders, and the conservative option of stem cell conditioned media injection into the shoulder joint.

Key Points of This Article

・A superior labrum tear (SLAP lesion) is an injury of the upper portion of the glenoid labrum that includes the attachment of the long head of the biceps tendon; it commonly occurs with repetitive overhead motion such as throwing or bench pressing

・Typical complaints include a deep, throbbing ache inside the shoulder, a clicking sensation during motion, and a sudden “dead arm” feeling — the pattern differs from frozen shoulder or rotator cuff tendinitis

・The labrum itself has poor blood supply and does not readily heal on its own, but much of the pain comes from surrounding synovitis and intra-articular inflammation, so shoulder-joint injection with stem cell conditioned media offers an option for calming the inflammatory environment

・For type II–IV lesions in young athletes, arthroscopic repair is the first-line choice; injection is not effective in every case of superior labrum tear

・Shoulder-joint injection plays the role of “suppressing pain and inflammation”; regaining motion requires combination with exercise therapy

What Is a Superior Labrum Tear — An Injury Occurring Inside the Shoulder Joint

Anatomical relationship of the labrum and the long head of the biceps tendon

The shoulder joint is structured with the round head of the humerus sitting on the shallow socket of the scapula called the glenoid. The rim of this socket is surrounded by a ring of fibrocartilaginous tissue called the glenoid labrum, which contributes to joint stability. The upper part of the labrum (at the 12 o’clock position) is where the long head of the biceps tendon — the tendon of the muscle on the front of the upper arm — attaches. An injury of the upper labrum including this biceps anchor, extending anteriorly and posteriorly, is called a Superior Labrum Anterior-Posterior lesion in English. Using the initials, it is generally referred to as a SLAP lesion, and in Japanese as jouhou kansetsushin sonshou (superior labrum tear).

Typical mechanism of injury

The injury is caused by forces such as (1) repetitive throwing motions in baseball players, (2) overhead serves in racket sports, (3) lifting heavy objects overhead as in bench press, and (4) impact when the outstretched hand hits the ground during a fall. In younger patients it is chiefly a fatigue-type injury from repetitive force, while in patients over 40 it is not unusual for the condition to develop from minor trauma against a background of age-related degeneration.

Why It Is Difficult to Distinguish from Frozen Shoulder or Rotator Cuff Tendinitis

Telling apart how the symptoms present

Frozen shoulder (adhesive capsulitis) is characterized by inflammation and contracture of the entire joint capsule, with restriction in every direction and nighttime aching. Rotator cuff tendinitis or rotator cuff tear typically produces the “painful arc” with worsening pain during arm abduction between 60 and 120 degrees. In contrast, in a SLAP lesion, the prominent complaints are (1) a deep, throbbing pain inside the shoulder joint, (2) a catching or clicking sensation during overhead motion, and (3) a sudden loss of arm strength (dead arm sign). A characteristic pattern is that everyday movements are surprisingly manageable, yet pain appears only with forceful arm motions such as throwing or a tennis smash.

Provocative tests and imaging

Provocative tests such as O’Brien’s test (active compression test) and Speed’s test are used in the physical exam, but their sensitivity and specificity are not perfect. For a definitive diagnosis, MRI with intra-articular contrast (MR arthrography) is considered the most accurate, and direct arthroscopic visualization serves as the final confirmation. For general information on shoulder disorders and treatment, the patient-facing content of the Japanese Orthopaedic Association is also a useful reference.

The Range That Shoulder-Joint Injection Can Target in a Superior Labrum Tear

Acting on the intra-articular inflammatory cycle

The labrum itself has poor vascularity and, once injured, is a tissue that cannot easily rely on self-repair. However, much of the pain that patients actually feel arises less from the labral tear itself and more from the synovitis, inflammation at the biceps anchor, and changes in the character of the joint fluid that accompany it. A stem cell conditioned media injection into the shoulder joint aims to calm this intra-articular inflammatory environment by delivering, into the joint cavity, culture supernatant containing growth factors such as TGF-β, IGF-1 and HGF along with anti-inflammatory cytokines. It is positioned not as an injection that re-attaches a torn labrum, but as an option that quiets the inflammatory chain and supports improvement in pain and mobility.

Being honest about the boundary with surgical indication

For Snyder classification type II (complete detachment of the biceps anchor) and higher, in young athletes aiming for return to sport, or in cases with clear joint instability, arthroscopic SLAP repair or biceps tenodesis is the first-line choice. On the other hand, when (1) there is no clear surgical indication on imaging, (2) the patient is middle-aged with rotator cuff degeneration, or (3) surgery is not desired and the goal is to improve activities of daily living with conservative care, it is worth incorporating a stem cell conditioned media shoulder-joint injection. It is not effective in every case, and the indication must be judged on the basis of orthopedic examination and imaging. Please also see our detailed page on joint injections with stem cell conditioned media.

Treatment Design and Aftercare Following Injection

Shoulder-joint injection is not a one-and-done treatment: typically 2–3 sessions are performed at intervals of several weeks during the induction phase, followed by a maintenance interval of every 3–6 months depending on response. Efficacy is evaluated over 4–8 weeks on the basis of pain scores (VAS), range of motion (forward elevation, external rotation, hand-behind-back), and difficulty in activities of daily living. On the day of the injection, bathing should be limited to a short shower, and alcohol and vigorous upper-limb exercise should be avoided. From the following day, daily life can proceed as usual; once pain has settled, running exercise therapy for the inner muscles (rotator cuff) and periscapular muscles in parallel makes it easier to improve the functional decline associated with a SLAP lesion.

Frequently Asked Questions

Q. Can a superior labrum tear be seen on X-rays?

X-rays show bony changes but the labrum itself is soft tissue and is not visualized. MRI, particularly contrast MR arthrography, is the most accurate modality for diagnosis, and when definitive confirmation is required, direct visualization by arthroscopy is performed.

Q. Can a stem cell conditioned media shoulder-joint injection heal the labral tear itself?

The effect of re-attaching torn labral tissue is not to be expected. This injection acts on the intra-articular inflammatory environment to improve pain and function; it is a separate matter from structural repair of the tear. When clear repair of the tear is needed, arthroscopic surgery becomes an option.

Q. Surgery has been recommended for me, but can I try to hold out with injections?

For type II–IV lesions in young patients aiming to return to sports, surgery is often the first choice. However, when the goal is to improve daily living without clear instability, or when a middle-aged or older patient wishes to avoid surgical risk, it is worth trying conservative care that includes a stem cell conditioned media joint injection. Please discuss individually with your treating physician.

Q. Is the injection painful? Are there side effects?

Injection into the shoulder joint cavity is combined with local anesthesia and performed as accurately as possible under ultrasound guidance. For 24–72 hours after the injection, tightness or mild pain at the injection site may occur (post-injection flare). Rarely, there are risks of infection or bleeding; if intense pain accompanied by fever occurs, please contact us promptly.

Q. How many sessions should I have?

Generally, 2–3 sessions in the induction phase, followed by maintenance intervals of every 3–6 months depending on response. Response varies among individuals; if improvement remains poor after 3 months, the treatment plan should be reconsidered.

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Medical Supervisor: Dr. Shin Moriwaki

Japan Society of Aesthetic Surgery (JSAS) Member / American Academy of Aesthetic Medicine Member

US Medical License Qualification (ECFMG certificate)

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📍AVAN TOKYO Ginza Regenerative Medicine

AVAN TOKYO Ginza Regenerative Medicine

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