Posterior shoulder instability, though less common than anterior instability, presents a unique challenge in orthopedic care. It involves the backward slipping or dislocation of the shoulder joint, often causing pain, weakness, or dysfunction. Recent advances in arthroscopic techniques now allow for a minimally invasive and highly effective approach to treating this condition.
How Common It Is and Who Gets It? (Epidemiology)
Posterior shoulder instability is relatively rare and is more common in athletes involved in overhead sports or activities requiring repetitive pushing or lifting motions. However, it can affect individuals of all ages, particularly those who have experienced trauma or microtrauma to the shoulder joint.
Why It Happens – Causes (Etiology and Pathophysiology)
Posterior shoulder instability is often caused by traumatic injury or repetitive strain, leading to excessive joint looseness. It can result from an event like a fall or from gradual wear-and-tear from repeated overhead activities. In some cases, instability is present due to congenital or anatomical factors, such as excessive capsular laxity.
How the Body Part Normally Works? (Relevant Anatomy)
The shoulder is a ball-and-socket joint, where the humeral head (ball) fits into the glenoid (socket). The shoulder’s stability is provided by the rotator cuff muscles, the labrum, and the joint capsule. When the shoulder’s stabilizing structures are weakened or damaged, the humeral head can slip backward, leading to instability.
What You Might Feel – Symptoms (Clinical Presentation)
Symptoms of posterior shoulder instability include pain, weakness, and a sensation of the shoulder slipping out of place. Patients may also experience a feeling of looseness, especially during overhead activities. Episodes of instability can vary in frequency and severity, often worsening with increased activity or trauma.
How Doctors Find the Problem? (Diagnosis and Imaging)
Diagnosis involves a detailed patient history, physical examination, and imaging studies such as X-rays and MRIs. MRAs (magnetic resonance arthrograms) can help visualize labral tears or capsular laxity. In some cases, even if the MRA appears normal, the physical exam may reveal signs of instability that require surgical intervention.
Classification
Posterior shoulder instability is typically classified based on the degree of translation of the humeral head. It can be divided into acute and chronic cases, with chronic instability often being associated with repetitive microtrauma. The severity of instability determines the treatment approach, ranging from physical therapy to surgical repair.
Other Problems That Can Feel Similar (Differential Diagnosis)
Posterior shoulder instability can be confused with other shoulder conditions, including rotator cuff tears, labral tears, or general shoulder pain caused by overuse or strain. Accurate diagnosis requires distinguishing between these conditions through clinical evaluation and imaging.
Treatment Options
Non-Surgical Care
- Physical therapy focused on strengthening the shoulder muscles and stabilizing the joint
- Rest and activity modification to avoid aggravating the condition
- Anti-inflammatory medications to reduce pain and swelling
Surgical Care
- Arthroscopic stabilization: the torn labrum is repaired using suture anchors, and the capsule may be tightened through plication
- Biceps tenodesis or SLAP repair if needed in conjunction with stabilization
Recovery and What to Expect After Treatment
Recovery from surgery generally involves wearing a sling for six weeks and limiting shoulder movement. Physical therapy begins after sling removal, and most patients return to normal activities within four to six months, depending on the severity of the instability.
Possible Risks or Side Effects (Complications)
Possible complications include infection, nerve injury, stiffness, recurrence of instability, and delayed healing. However, with proper surgical technique and rehabilitation, these risks are minimal.
Long-Term Outlook (Prognosis)
Most patients who undergo arthroscopic stabilization experience significant improvement in shoulder stability, strength, and function. Full recovery typically takes four to six months, with a return to sports or other high-demand activities expected at that point. However, some patients with voluntary instability or prior surgeries may not achieve full relief.
Out-of-Pocket Costs
Medicare
CPT Code 29806 – Labral Repair / Capsular Plication (Shoulder Stabilization Surgery): $250.66
CPT Code 29828 – Biceps Tenodesis (Arthroscopic Biceps Tendon Repair): $216.87
CPT Code 29807 – SLAP Repair (Arthroscopic Repair of Superior Labrum Anterior-Posterior Tear): $244.79
Medicare Part B typically covers 80% of the approved cost for these procedures once your annual deductible has been met, leaving you responsible for the remaining 20%. Supplemental Insurance plans such as Medigap, AARP, or Blue Cross Blue Shield generally cover the remaining 20%, significantly reducing or eliminating out-of-pocket expenses for Medicare-approved surgeries. These plans work alongside Medicare to fill the coverage gap and reduce financial responsibility.
If you have Secondary Insurance, such as TRICARE, an Employer-Based Plan, or Veterans Health Administration coverage, it acts as a secondary payer. These plans usually cover any remaining balance, including coinsurance or small deductibles, which typically range from $100 to $300, depending on your plan and provider network.
Workers’ Compensation
If your shoulder surgery (Labral repair, Biceps tenodesis, or SLAP repair) is required due to a work-related injury, Workers’ Compensation will cover all associated medical expenses, including surgery, rehabilitation, and follow-up care. You will not have any out-of-pocket expenses, as the employer’s insurance carrier directly covers all approved treatments.
No-Fault Insurance
If your shoulder surgery is related to an automobile accident, No-Fault Insurance will typically cover the total cost of your treatment, including surgery and postoperative care. The only potential out-of-pocket cost may be a small deductible or co-payment depending on your policy.
Example
John Walker underwent SLAP repair surgery (CPT 29807) and required a biceps tenodesis (CPT 29828) to address his shoulder instability. His estimated Medicare out-of-pocket cost was $244.79 for the SLAP repair, $216.87 for biceps tenodesis, and $250.66 for labral repair/capsular plication (CPT 29806). Since John had supplemental insurance through AARP Medigap, his remaining balance was fully covered, leaving him with no out-of-pocket expenses for the procedures.
Frequently Asked Questions (FAQ)
Q. What is posterior shoulder instability?
A. Posterior shoulder instability occurs when the ball of the shoulder repeatedly slips out of the back of the socket.
Q. What are common causes of posterior shoulder instability?
A. It can result from repetitive overhead activities, trauma, or congenital conditions that lead to looseness in the joint.
Q. What are the symptoms of posterior shoulder instability?
A. Symptoms include pain, a feeling of looseness, and episodes where the shoulder feels like it is slipping out of place.
Q. How is posterior shoulder instability diagnosed?
A. Diagnosis involves a detailed history, physical examination, and imaging such as X-rays and MRIs.
Q. What are the non-surgical treatments for posterior shoulder instability?
A. Non-surgical options include physical therapy to strengthen shoulder muscles and activity modification.
Q. When is surgery recommended for posterior shoulder instability?
A. Surgery is recommended when non-operative treatments fail or when instability significantly affects daily life or sports performance.
Q. What does arthroscopic treatment of posterior shoulder instability involve?
A. It involves the use of a camera and small instruments inserted through tiny incisions to repair and tighten the damaged structures in the shoulder.
Q. How is the torn labrum treated during surgery?
A. The torn labrum is reattached to the bone using suture anchors during the arthroscopic procedure.
Q. How long does the arthroscopic surgery take?
A. The surgery typically takes about 1 to 2 hours.
Q. What type of anesthesia is used for the procedure?
A. General anesthesia combined with a regional nerve block is usually used.
Q. Will I need to wear a sling after surgery?
A. Yes, a sling is typically worn for 4 to 6 weeks to protect the repair.
Q. When can physical therapy start after surgery?
A. Physical therapy usually begins after the sling is removed to help restore motion and strength.
Q. How long is the recovery after arthroscopic posterior shoulder stabilization?
A. Full recovery typically takes about 4 to 6 months, depending on the individual and the extent of the injury.
Q. Can patients return to sports after surgery?
A. Most patients can return to sports after completing rehabilitation, usually around 4 to 6 months post-surgery.
Q. What are the risks of arthroscopic shoulder surgery?
A. Risks include infection, stiffness, nerve injury, recurrence of instability, and the need for further surgery.
Q. What are the benefits of arthroscopic surgery compared to open surgery?
A. Arthroscopic surgery is less invasive, results in smaller scars, and typically allows for a quicker recovery.
Summary and Takeaway
Posterior shoulder instability can cause significant pain and dysfunction, particularly in athletes or individuals who perform repetitive overhead activities. The condition is often misdiagnosed due to its similarity to other shoulder disorders, but arthroscopic surgery provides a minimally invasive and effective solution for most patients. Surgery typically involves labral repair, capsular tightening, and sometimes additional procedures such as SLAP repairs or biceps tenodesis. Post-surgery, patients generally experience significant improvement, with most returning to full activity within 4-6 months. Recovery success is higher in those with traumatic instability and first-time surgery, while patients with voluntary instability or prior surgeries may experience less favorable outcomes.
Clinical Insight & Recent Findings
A recent study evaluated the outcomes of arthroscopic treatment for posterior shoulder instability, specifically focusing on return-to-sport rates in athletes. The study found that 98% of athletes were able to return to some level of sport activity, with 51% returning to their preinjury level. Notably, athletes with a traumatic injury experienced a significantly higher rate of return to the same sport compared to those with atraumatic instability. The results also highlighted a low recurrence rate of instability (7.5%) after surgery. These findings underscore the effectiveness of arthroscopic posterior labral reconstruction in treating shoulder instability, with most athletes achieving positive functional outcomes. (“Study on posterior shoulder instability – see PubMed.“)
Who Performs This Treatment? (Specialists and Team Involved)
Shoulder specialists, including orthopedic surgeons and sports medicine physicians, are primarily involved in the treatment of posterior shoulder instability. Physical therapists are essential in helping patients regain strength and mobility following surgery.
When to See a Specialist?
Seek a specialist if you experience ongoing shoulder pain, instability, or weakness that interferes with daily activities or athletic performance, especially if non-surgical treatments have not been effective.
When to Go to the Emergency Room?
If you experience severe pain, significant loss of shoulder function, or signs of infection after surgery, such as fever or redness, seek emergency care.
What Recovery Really Looks Like?
Post-surgery recovery involves wearing a sling for 4-6 weeks, followed by physical therapy. Patients can generally return to normal activity after 4-6 months, with athletes requiring full rehabilitation for optimal performance.
What Happens If You Ignore It?
If left untreated, posterior shoulder instability can lead to recurrent dislocations, progressive joint damage, and long-term shoulder dysfunction. Early treatment, including physical therapy or surgery, is crucial to avoid these outcomes.
How to Prevent It?
Preventing posterior shoulder instability involves maintaining strong, balanced shoulder muscles and avoiding repetitive overhead motions that could strain the joint. Proper technique during athletic activities can also reduce the risk.
Nutrition and Bone or Joint Health
A diet rich in calcium, vitamin D, and omega-3 fatty acids can support joint health, reduce inflammation, and aid recovery after surgery.
Activity and Lifestyle Modifications
Avoid activities that strain the shoulder joint, particularly those involving overhead lifting or repetitive movements. Strengthening the rotator cuff and scapular stabilizers can help prevent instability.
