Patella Instability
Patella (kneecap) dislocations are a common injury seen in sport and account for 2-3% of all knee injuries. They occur when the patella slides outside of its groove within the distal part of the femur (thigh bone) and travels laterally. Patella dislocations can affect athletes of all ages, most commonly seen in adolescent athletes. These injuries are quite painful in the acute stages especially if the joint hasn’t been reduced. Following reduction, acute injury management is vital as these injuries have a high reoccurrence rate following a first-time dislocation, with some studies showing up to 60% of patients will suffer a re-injury. This shows the importance of effective first line management for patella dislocations to ensure adequate healing of structures and preventative measures to minimise the risk of re-injury.
What Is a Patella Dislocation?
The patella is the small bone which sits at the anterior (front) aspect of the knee, it sits within a small groove of the femur allowing smooth motion and function. This joint is supported by the medial patellofemoral ligament (MPFL), along with the natural bony structure of the patellofemoral joint. Patella instability is a continuum ranging from subluxations where the patella slides laterally but still maintains contact within the groove, to a dislocation where there is complete separation of the two bony surfaces. These injuries can result in significant pain and instability of the knee.
Causes of Patella Dislocations
Acute patella dislocations typically occur as a result of trauma and can be divided into contact and non-contact mechanisms. A non-contact patella dislocation typically occurs from a twisting manoeuvrer to the knee which can occur in changes of direction.
Whereas a contact mechanism occurs from a direct blow to the medial aspect of the knee, or when a player is twisted forcing their tibia to externally rotate on a fixed foot. Patients will often describe feeling a pop, resulting in pain, deformity and associated swelling.
Patella dislocations can also occur due to generalised ligamentous laxity, however these athletes tend to have recurrent patella subluxations compared to an acute dislocation.
Other factors that increase the risk of patella dislocations are:
Anatomical variations such as patella alta, trochlea dysplasia and an increased Q angle.
Connective tissue disorders such as Marfan syndrome and Ehlers-Danlos.
Weakness of muscles such as the quadriceps, in particular the vastus medialis.
Symptoms of Patella Dislocation
Feeling of a pop following a non-contact twisting or direct blow
Intense Pain: These injuries cause sudden and severe pain in the knee area, but settle quickly following the reduction of the joint.
Visible Deformity: When dislocated, the patella will sit laterally on the knee.
Swelling: Rapid swelling occurs following this injury and is a common sign following an acute injury. However, there may be no visible swelling with recurrent dislocations.
Tenderness: Sensitivity around the kneecap and surrounding areas.
Instability: The feeling that the knee is giving way or catching, particularly worse when bending the knee or kneeling.
Immediate Treatment Steps
Acute management of a patella dislocation involves the reduction of the dislocation. This procedure will typically be performed in the emergency department or by a medical professional. You will then be placed in an extension knee range of motion brace or patella stabilising sleeve to help allow the soft tissues to heal.
It is important to undergo investigative imaging to rule out any associated fractures and to determine the extent of soft tissue damage, as this will guide us in your rehabilitation and determine if operative management is required. X-rays are useful to rule out fractures which can occur with these types of injuries, while MRIs provide a detailed view of soft tissue injuries, including the MPFL and any potential chondral damage.
Physiotherapy is recommended to be commenced in the acute stages with the goal to decrease pain, swelling and begin reactivation of the quadriceps and supporting structures.
Treatment Options
First time patella dislocations are often managed conservatively with bracing and rehabilitation. A typical return to play timeline for a non-operative managed dislocation is 4-6 months. Surgical intervention is considered for dislocations with associated osteochondral damage, MPFL disruption, recurrent dislocations and failure of conservative management. Surgically managed dislocations will require a rehab of 6-9 months depending on the associated injuries.
Recovery and Rehabilitation
Following your injury, a structured rehab plan is essential for recovery and an effective return to sport. Here at Rehab Advantage, a patella dislocation rehab will follow the following phases.
Acute Repair:
This phase will differ dependent on whether you have undergone surgery or are being managed conservatively. During this phase you will be placed in a ROM brace locked in extension with the use of crutches to aid in mobility. Due to the risk of re-injury, it is important to facilitate repair of the damaged ligaments to develop good anatomical healing and scar formation.
Our main goals for this phase are to:
Progressively increase of knee range of motion but back to greater than 90 degrees.
Reduction of pain and swelling.
Re-activation of the quadriceps muscles with the use of electrical stimulation to overcome muscle inhibition which is associated with knee injuries.
Maintenance of hamstring and calf musculature.
Lateral hip control exercises.
Energy Expenditure.
Reload Phase:
In this phase you will begin weaning from your range of motion brace and progress into more strength-based lower limb loading. Your rehab program will transition from bilateral to unilateral orientated exercises to challenge stability and capacity.
Our main goals for this phase are to:
Normalise your gait pattern.
Weaning of ROM brace.
Quadricep strength progressions.
Foot, knee, hip and core strengthening.
Introduction of plyometric loading and run drilling.
Rebuild Phase:
The main addition to this phase is the introduction of your rehab running which is done on field and supervised by one of our physiotherapists, here you will progress through the different stages of:
Linear running loads
Speed and Planned change of direction
Reactive change of direction and sports specific conditioning
Our rehab goals for this phase are to:
Gradually build running loads.
Consolidate strength and power.
Normalise your plyometric profiling.
Progression of sport specific skills in a controlled environment.
Return to Training and Sport
Our final two phases are aimed at a staged return to training building from controlled to chaos, before a return to competition and full functional participation. Our goal during these phases is to get you back performing in your sport.
Our main goals for this phase are to:
Progress team training loads from controlled to chaos.
Maintain strength, power and plyometric loading.
Educate on ongoing resilience exercises to help prevent re-injury.
Conclusion
Patella dislocations can be painful and lead to ongoing instability when not managed appropriately, but understanding the causes, symptoms, and treatment options can help you manage the injury effectively and minimise the risk of chronic instability. Here at Rehab Advantage, we will guide you through your rehabilitation to ensure you are able to return to your normal activities and sport safely.