AC joint ligament overload

Anatomy: What stabilizes the acromioclavicular joint?

The AC joint connects the outer end of the collarbone (clavicle) with the shoulder roof (acromion). It enables small compensatory movements and transfers forces between the arm, shoulder blade and torso.

• AC ligaments (acromioclavicular ligaments): directly stabilize the joint.
• Coracoclavicular ligaments (conoid and trapezoid ligaments): secure the clavicle against the coracoid process - central stabilizers.
• Joint capsule and disc: provide additional stability and cushioning.
• Muscular guidance: rotator cuff and scapula leader (e.g. trapezius, serratus anterior).

When overloaded, the AC and coracoclavicular ligament structures in particular become irritated. This can also affect the interior of the joint (synovitis).

What does AC joint ligament overload mean?

By overload we mean repeated, cumulative microtraumas to the ligament fibers without acute tearing. The tissue reacts with inflammation, swelling and pain. If incorrect or overloading continues, there is a risk of a chronic course - including instability or a so-called "weightlifter's shoulder" (irritation/osteolysis near the bone at the end of the collarbone).

• No acute trauma such as a fall, but repeated peak loads
• Pain provocation during horizontal adduction (arm across the body)
• Pressure pain exactly over the shoulder joint

Causes and risk factors

• Strength training with high loads: bench presses, dips, close shoulder presses
• Overhead or lateral loads at work (painter, assembly, crafts)
• Contact sports (e.g. rugby, handball) – repeated blows to the shoulder
• Technical errors: grip width too wide, lack of scapular stability, lack of warm-up phase
• Existing AC joint osteoarthritis or previous sprains
• Unfavorable regeneration times, lack of sleep, nicotine

Several factors often come into play: increasing the load too quickly, a lack of shoulder blade control and high repetition numbers without sufficient recovery.

Typical symptoms

• Locally tender point on the upper acromion (shoulder corner)
• Pain during cross-body adduction (arm across the body) and when lifting overhead
• Pain when pushing/straining, hanging, carrying in front of the body
• Post-exercise pain after training, start-up pain in the morning
• Sometimes swelling or a feeling of tenderness over the joint
• Lying on your side on the affected shoulder is painful

When should you see a doctor quickly?

• Sudden deformity, fall trauma, visible step at the corner of the shoulder
• Radiating pain with sensory disturbances or loss of strength in the arm
• Pain at rest, fever, redness and significant overheating
• Pain-related restriction of movement that does not improve within a few days

Diagnostics in our practice in Hamburg

The diagnosis is based on anamnesis, clinical tests and imaging procedures - with the aim of reliably identifying the structures that cause pain and ruling out other causes.

• Clinical examination: palpation of the AC joint; cross-body adduction (Scarf test); Paxinos sign; O’Brien test for differentiating AC and labral causes.
• Functional analysis: scapula movement, rotator cuff strength, posture and thoracic mobility.
• Ultrasound: Depiction of joint effusion, inflammatory changes, dynamic pain provocation.
• X-ray (Zanca image): assessment of the AC joint gap, bony changes; if necessary, two-sided comparison.
• MRI: Evidence of ligament irritation, synovitis, bone marrow edema or distal clavicle osteolysis; Exclusion of tendon/labral lesions.

Stress recordings are rarely necessary. What is crucial is the correlation between the findings and your symptoms.

Differential diagnoses: What else is possible?

• AC joint arthrosis with synovitis
• Distal clavicle osteolysis (“Weightlifter’s Shoulder”)
• Rotator cuff tendinopathies (e.g., supraspinatus, infraspinatus, subscapularis, teres minor)
• Subacromial impingement, calcifications
• Biceps tendonitis (long biceps tendon, LBS)
• Labrum/SLAP lesion
• Cervical nerve root irritation (cervical spine) or myofascial pain

Treatment goals and conservative approach

The aim is to reduce pain, calm inflammation, restore scapula control and gradually increase stress. Conservative therapy is usually successful.

• Medication: Short-term anti-inflammatory painkillers (e.g. NSAIDs) can be useful - only after individual consideration and tolerability.
• Taping/bandages: Kinesiological tape or stabilization tape to relieve the AC joint during periods of stress.
• Manual therapy: gentle mobilizations, soft tissue techniques, posture training.

Physiotherapy: proven content

• Scapula setting: Activation of the serratus anterior and lower trapezius (e.g. wall sliding, Y and W positions without pain provocation).
• Isometric Rotators: Internal/external rotation against Theraband with elbows at body; initially painless, short holding times.
• Closed chain: quadruped position with slight weight shifts; later modified push-ups on the wall.
• Stretching: Gentle posterior capsule stretches; Cross-body stretch only if not painful.
• Postural and breathing work: thoracic extension, thoracic spine mobilization using a roller or chair back.
• Technique coaching: Reduce grip width when pressing, set shoulder blades, control speed.

A pain-adapted dosage is important: slight pulling is tolerable, stabbing AC pain is a stop signal.

Injections and regenerative procedures: when does it make sense?

If inflammation persists despite consistent therapy, an ultrasound-targeted injection into the AC joint can be considered.

• Local cortisone therapy: can reduce inflammation in the short to medium term. The number and spacing of injections are chosen individually and cautiously.
• Local anesthetic diagnostics: Pain reduction after trial injection suggests the AC joint as the source.
• Hyaluronic acid/PRP: Evidence for AC joint ligament overload is limited. Can be discussed in individual cases - after weighing up the benefits and risks and without any promise of cure.

Regenerative options do not replace active rehabilitation, but can complement it – if indicated.

Everyday life, work and sport: practical recommendations

• Reduce short-term cross-stressing movements (arm in front of the body, heavy carrying).
• When training: choose a narrower grip, elbows closer to the body; Reduce load by 30-50%, pace calmly, no “bounce” on the chest.
• Temporarily avoid dips, heavy bench presses, and close overhead presses; Alternatives like neutral grip dumbbell press.
• Warmth before, cold after exercise - depending on individual feelings.
• Sleep: lying on your side on the pain-free side, pillow for arm support.

Return-to-Sport: gradual increase when everyday stress is possible with little pain, strength is symmetrical and specific tests (e.g. cross-body adduction) no longer cause significant pain.

Course and prognosis

Most patients benefit from consistent conservative therapy within 6-12 weeks. The course depends on training discipline, technique and accompanying factors (e.g. osteoarthritis).

• Good prognosis with early load adaptation and targeted physiotherapy
• Increased risk of relapse if load increases too quickly
• Chronic courses are rare, but are promoted by persistent incorrect loading

When should surgery be considered?

Surgery is rarely necessary for pure ligament overload. It only comes into consideration if conservative measures do not achieve the desired result despite sufficient duration and quality or if there are additional structural problems.

• Persistent AC joint synovitis with significant impairment despite therapy
• Severe AC osteoarthritis/bony conflicts that cannot be controlled conservatively
• Instability after repeated strains (to be distinguished from acute AC joint rupture)

Possible procedures (e.g. arthroscopic partial resection of the lateral clavicle) are discussed individually and only after conservative options have been exhausted.

Prevention: this is how you prevent it

• Progressively increase the load in training, plan deload phases
• Clean technique: shoulder blade tension, neutral grip position, not an extremely wide grip width
• Compensatory training: Strengthen back and scapular stabilizers
• Warm-up: 10-15 minutes with light sets and mobilization
• Regeneration: pay attention to sleep, nutrition, breaks and stress management

This is how we support you in Hamburg

In our practice at Dorotheenstrasse 48, 22301 Hamburg, you will receive a structured assessment of your shoulder pain including targeted therapy planning. We rely on evidence-based, conservative concepts, closely coordinated physiotherapy and – if necessary – gentle, image-guided injections.

• Individual load analysis and technical advice
• Coordination with experienced shoulder physiotherapists
• Transparent information about the benefits and limitations of possible measures