What causes rotator cuff tears?

Rotator cuff tears have two main causes. Acute tears result from a sudden injury — such as a fall onto an outstretched arm, a heavy lift, or a direct blow to the shoulder — and are often eligible for ACC cover in New Zealand. Degenerative tears develop gradually over time as the tendon weakens with age and repeated use, and are more common in patients over 50. Risk factors include heavy manual work, overhead sport, smoking, and previous shoulder injuries. Both types can cause significant pain and weakness and may require surgical repair.

Is shoulder dislocation covered by ACC in New Zealand?

Yes. Shoulder dislocations sustained through an accident — including sporting injuries — are eligible for ACC cover in New Zealand. ACC can fund the cost of specialist assessment, MRI, surgery, and physiotherapy rehabilitation. Your GP or physiotherapist can lodge an ACC claim and refer you to a specialist at the same time. If you have dislocated your shoulder during sport or through a fall, ask your GP about ACC eligibility at your next appointment.

When does shoulder pain need surgery?

Most shoulder problems are managed initially with physiotherapy and do not require surgery. Surgery is typically considered when: symptoms have not improved after a structured course of physiotherapy (usually 8–12 weeks); there is a significant structural injury such as a full-thickness rotator cuff tear, shoulder dislocation with labral damage, or a SLAP tear; the shoulder is repeatedly dislocating; or pain and weakness are significantly affecting quality of life and function. A specialist assessment with appropriate imaging — usually an MRI — is needed to determine whether surgery is the right option for your specific condition.

Shoulder Conditions

Dr. Boyle treats the following shoulder conditions:

Rotator cuff tears

The rotator cuff is a group of four muscles and tendons that stabilise the shoulder joint and allow you to lift and rotate your arm. Tears range from small partial tears to complete full-thickness ruptures and can result from an acute injury — such as a fall or lifting accident (often ACC-eligible) — or from gradual degeneration over time.

Symptoms include shoulder pain (often worse at night or when reaching overhead), weakness, and difficulty with everyday tasks such as dressing or lifting. Treatment depends on the size of the tear and your activity level — many small tears respond well to physiotherapy, while larger or acute tears benefit from arthroscopic surgical repair.

For more information, read Dr Boyle's article on rotator cuff surgery.

Shoulder impingement

Shoulder impingement occurs when the tendons of the rotator cuff become pinched as the arm is raised, causing pain at the front or side of the shoulder. It is one of the most common causes of shoulder pain in adults and is often related to rotator cuff pathology, including partial tears or tendinopathy.

Many cases respond well to a structured physiotherapy programme and, if needed, a corticosteroid injection. For persistent cases that do not improve with non-operative treatment, arthroscopic subacromial decompression can relieve the pressure on the tendons and restore comfortable shoulder function.

Calcific Tendonitis

Calcific tendonitis occurs when calcium deposits form within the rotator cuff tendons — most commonly the supraspinatus. The condition can cause severe, acute shoulder pain (during the resorptive phase) or more chronic aching discomfort. It is more common in patients aged 30–60. Many cases resolve spontaneously over months to years. Treatment options include physiotherapy, non-steroidal anti-inflammatory medication, ultrasound-guided needling and lavage (barbotage), and — in refractory cases — arthroscopic removal of the calcium deposit.

Shoulder dislocation and Instability

Shoulder dislocation occurs when the ball of the shoulder joint (the humeral head) slips out of the socket (the glenoid). It is the most commonly dislocated major joint and is a frequent injury in contact sports including rugby, netball, and martial arts. Most acute dislocations are ACC-eligible.

Following a first dislocation, the risk of the shoulder dislocating again is high — particularly in younger, active patients. Repeated dislocations cause progressive damage to the labrum and capsule, and increase the risk of arthritis over time. Arthroscopic stabilisation surgery (Bankart repair) is highly effective in reducing recurrence and is recommended for active patients who wish to return to sport.

Bankart Lesion

A Bankart lesion is a tear of the anterior (front) labrum — the cartilage rim of the shoulder socket — that occurs as a result of shoulder dislocation. It is the most common structural injury following a first-time dislocation and is present in the majority of patients with recurrent shoulder instability.

When the shoulder dislocates, the humeral head (ball) tears away from the front of the labrum as it exits the joint. If this tear does not heal adequately, the shoulder socket loses its natural depth and the labrum can no longer function as a restraint against further dislocation. This is why the risk of re-dislocation is high following a first dislocation — particularly in younger, active patients.

A Bankart lesion is typically diagnosed on MRI arthrogram. Arthroscopic Bankart repair — reattaching the torn labrum to the rim of the socket using small anchors — restores stability effectively and is the standard surgical treatment for active patients with instability caused by a Bankart lesion. ACC cover applies when the lesion resulted from an acute injury.

Posterior Labral Tears

The posterior labrum is the back portion of the cartilage ring surrounding the shoulder socket. Posterior labral tears are less common than anterior (Bankart) tears and are typically seen in overhead athletes, weightlifters, and those who have sustained a posterior shoulder dislocation. Symptoms include deep posterior shoulder pain, pain with pushing or bench press movements, and a feeling of instability at the back of the shoulder. Arthroscopic posterior labral repair restores stability and allows return to sport.

Slap Tears

A SLAP tear (superior labrum anterior to posterior) is a tear of the top portion of the labral ring that surrounds the shoulder socket. It is commonly seen in throwing athletes, overhead workers, and those who have sustained a fall onto an outstretched arm. ACC cover applies to acute labral injuries caused by injury.

Symptoms include a deep aching pain in the shoulder, a clicking or catching sensation, reduced throwing speed or accuracy, and pain with overhead activities. Depending on the tear type and patient factors, treatment options include arthroscopic labral repair or biceps tenodesis (reattaching the biceps tendon at a lower point on the arm bone).

Frozen Shoulder (Adhesive Capsulitis)

Frozen shoulder is a condition in which the capsule surrounding the shoulder joint becomes inflamed and thickened, causing progressive stiffness and pain. It typically develops in three stages — a painful "freezing" phase, a stiff "frozen" phase, and a gradual "thawing" phase — and can last 12–24 months.

It is more common in people aged 40–60, in those with diabetes, and following periods of shoulder immobilisation. Most cases improve over time with physiotherapy and corticosteroid injections. In cases where stiffness fails to resolve, arthroscopic capsular release is an effective surgical option that accelerates recovery of movement.

Long head of biceps tendonitis

The long head of the biceps tendon attaches to the top of the shoulder socket (labrum) and runs through the front of the shoulder joint. It is a common source of anterior shoulder pain and is frequently involved alongside rotator cuff pathology or SLAP tears. Symptoms include a deep aching pain at the front of the shoulder and upper arm, aggravated by lifting and carrying. Treatment ranges from physiotherapy and corticosteroid injection to biceps tenodesis — surgically relocating the tendon anchor — in persistent or high-demand cases.

Acromioclavicular (AC) joint dislocation

The acromioclavicular joint connects the collarbone (clavicle) to the tip of the shoulder blade (acromion). AC joint dislocations — commonly called a "separated shoulder" — typically result from a direct fall onto the shoulder and are frequently seen in rugby and cycling. Most ACC-eligible. Mild to moderate separations (grades I–III) are managed non-operatively with a sling and physiotherapy. Significant dislocations (grades IV–VI) with persistent pain or cosmetic deformity may benefit from surgical stabilisation.

Acromioclavicular (AC) joint arthritis

Arthritis of the AC joint causes pain and tenderness directly at the top of the shoulder, often worsened by reaching across the body and overhead lifting. It is a common finding in older active patients and those with a history of AC joint injury. AC joint arthritis frequently coexists with rotator cuff pathology. When non-operative measures — including physiotherapy and corticosteroid injection — fail to provide lasting relief, arthroscopic excision of the end of the clavicle (Mumford procedure) is an effective surgical option.

Suprascapular nerve decompression

The suprascapular nerve supplies the infraspinatus and supraspinatus muscles of the rotator cuff. Compression of this nerve — typically at the suprascapular or spinoglenoid notch — causes deep, poorly localised shoulder aching, weakness of external rotation, and in some cases visible wasting of the muscles at the back of the shoulder blade. It is seen in overhead athletes and can occur alongside a paralabral (ganglion) cyst. Treatment depends on the cause: cyst decompression for ganglion-related compression, or arthroscopic nerve decompression in other cases.

To arrange a specialist assessment for any of the above conditions, ask your GP or physiotherapist to refer you to Dr. Matthew Boyle at Auckland Bone and Joint Surgery. Referrals can be sent via HealthLink EDI: drmboyle, or by calling 09 281 6733. Dr. Boyle consults at AUT Millennium, 17 Antares Place, Rosedale, North Shore Auckland.