Multidirectional instability refers to a condition where the shoulder joint becomes unstable and may partially slip out of place (subluxation) or completely dislocate in more than one direction. This instability typically involves the front (anterior), back (posterior), and bottom (inferior) parts of the shoulder. It can be a result of naturally loose ligaments, repetitive strain from certain sports or work activities, or, in some cases, congenital conditions like Ehlers-Danlos or Marfan syndrome.
Understanding the Treatment Path
Conservative First: Why Rehabilitation Is the Starting Point
For most patients with MDI, the first line of treatment is not surgery but a structured, personalized physical therapy program. The goal of this approach is to strengthen the muscles around the shoulder, particularly the rotator cuff and the muscles that control the shoulder blade (scapula). These muscles are vital in keeping the shoulder joint properly aligned and stable during movement.
The Watson Six-Stage Rehabilitation Program
The Watson MDI Program is a step-by-step physiotherapy plan designed to restore shoulder stability through targeted muscle activation and progressive movement control.
Stage 3: Gaining Flexion Control (0°–45° Elevation)
In this stage, the focus is on gaining control in the forward movement (flexion) of the arm up to 45 degrees. This is an important range for daily activities. Exercises often begin with just the weight of the arm and gradually include light resistance using elastic bands or light dumbbells.
This stage is split into:
- Scapula Phase: Reinforces control of the shoulder blade, especially during forward movements.
- Arc of Motion Phase: Uses resistance bands to improve shoulder movement while maintaining proper shoulder blade alignment.
Important Note: For patients with a tendency for the shoulder to slip backwards, special care is taken to avoid worsening instability during these movements.
Stage 4: Reaching Mid-Range (45°–90° Elevation)
Here, patients work to stabilize the shoulder as the arm moves higher. This includes:
- External and internal rotations at 90°: Important for sports and tasks like reaching overhead.
- Horizontal motion control: Useful for tasks like driving or reaching across the body.
Patients use resistance bands and may increase the load gradually. The focus remains on maintaining perfect control of shoulder movement and scapular stability at every step.
Stage 5: Strengthening the Deltoid Muscle
This phase strengthens the deltoid, the muscle that forms the shoulder’s contour. Each of its parts—front, middle, and back—is worked individually. Exercises are customized to avoid triggering instability.
- Posterior Deltoid: Bent-over rows.
- Anterior Deltoid: Front raises performed while seated or lying down.
- Middle Deltoid: Side raises using short lever arms (bent elbows) progressing to longer arm movements.
Exercises are gradually intensified using weights and resistance bands, depending on the patient’s capability.
Stage 6: Real-Life and Sports-Specific Movements
Once strength and control are established, therapy shifts toward replicating real-life tasks or sports activities.
This stage includes:
- Functional drills mimicking activities like swimming, throwing, or lifting.
- Part practice: Isolating parts of a complex movement (like just the catch phase of a swim stroke).
- Whole practice: Performing the full movement or task under supervision.
Patients are trained to perform high-volume, low-load or high-load, low-volume repetitions, depending on their job or sport. If instability persists, weight-bearing exercises are avoided.
How Do You Know You’re Ready to Progress?
Progression through the stages is carefully monitored:
- No pain during exercises.
- Perfect control of shoulder movement.
- Ability to resist force applied by the therapist without losing control.
Exercises from earlier stages are not discarded; they are continued at higher levels of difficulty or resistance.
When Rehabilitation Isn’t Enough: Surgical Options
If symptoms persist after several months of consistent therapy, surgery may be recommended.
Two Main Surgical Techniques
- Open Inferior Capsular Shift
- Involves cutting and tightening the shoulder capsule to reduce looseness.
- Often used in patients with very redundant (loose) shoulder capsules.
- Considered very effective with long-term results showing low rates of redislocation.
- Arthroscopic Capsular Plication
- Minimally invasive, performed through small incisions with a camera.
- Allows surgeons to address multiple issues at once (e.g., torn labrum).
- Can result in less post-operative stiffness and faster recovery.
Both procedures aim to reduce the volume of the capsule, essentially tightening the shoulder joint to prevent excess movement.
Important Considerations Before Surgery
- Patients with ligamentous laxity (naturally very flexible joints) may not respond as well to surgery.
- Voluntary dislocators (those who can move their shoulder out on purpose) often do worse with surgery.
- Surgery is not recommended if there are major underlying issues such as poor posture, weak neck muscles, or thoracic outlet syndrome until those are addressed.
Long-Term Management and Maintenance
After successfully completing the program (with or without surgery), patients should continue a maintenance program two to three times per week. This typically includes:
- One day of band exercises.
- One day of weight exercises.
Ongoing activity modifications may be necessary. For example:
- Avoiding contact sports or heavy weightlifting.
- Being mindful of how much load is placed on the shoulder during daily tasks.
Final Thoughts
MDI of the shoulder can be a challenging condition—but with the right approach, most patients can return to a functional, active life. A stepwise, personalized rehabilitation program is the foundation of care. Surgery, when needed, is tailored to each individual’s anatomy and lifestyle.
