- Patellar instability can range from recurrent instability to chronic subluxation to dislocation of the patella.
- imbalance of extensor mechanism,
- patellofemoral joint dysplasia,
- congenital deficiency of the femoral trochlea
- excessive tibial torsion, hip anteversion or pronation of the foot
- Patients often complain of pain at the medial aspect and distal pole of the patella with a feeling of giving way or instability during walking or movement. Also, patients report of a catching or pseudo-locking sensation with snapping and popping of patella with episodes of effusion following.
- Fairbanks sign positive with pain or patient apprehension on lateral displacement of a patella.
- The important clinical finding for suspecting patellar instability is the lateral displacement of the patella by more than 50% of total patella width performed with the knee flexed to 20 – 30 degrees.
- Dynamic patellar stabilization exercises by improving extensor mechanism imbalance.
- Quadriceps and hamstring strengthening exercises within a pain-free range. Use of patellar bracing or taping the patella medially may be helpful to enhance stability during an early phase of rehabilitation and functional activities.
- VMO activation –isometric quad sets, leg press, lateral step-ups, terminal knee extension.
- Functional exercises like stair climbing, bicycling, squatting can be carefully included in during the rehabilitation.
– complete displacement of the patella out of femoral trochlea.
Acute patellar dislocation
- Due to direct trauma or pre-existing lower extremity malalignment.
- A patient comes with severe pain, swelling and loss of mobility. Generally, patient reports the feeling of patella being out of place.
- Immobilization of knee in extension with lateral doughnut pad which helps to maintain the patella medially tilted during immobilization period.
- Quads re-education with quads settings in extension. Use of electrical muscle stimulation if self-activation of quads is very low.
- Gradual progression of AROM and strengthening exercises.
Recurrent Patella dislocation
- The knee should be immobilized as for acute dislocation until pain and inflammation subside. The rehabilitation protocol can be same as for the chronic subluxation of the patella with progressive exercises to improve ROM and extensor mechanism.
Lower extremity biomechanical dysfunction
A non-traumatic patellofemoral pain is often associated with lower extremity biomechanical dysfunction. Often patients do not notice the dysfunction until they are in a significant patellofemoral pain and dysfunction. Studies have shown that a subtle alteration in normal mechanics may have a significant effect on daily activities, ambulation and sporting activities resulting in a patellofemoral disorder over a period of time. Some of the biomechanical issues are listed below:
- Excessive subtalar joint or foot pronation – caused due to intrinsic muscle imbalance of foot – results in the increased medial tibial rotation – which in turn forces the patella to displace laterally.
- The weakness of hip external rotators and tightness of calf muscles may lead to compensatory foot pronation.
- Weakness in quadriceps or medial quadriceps can affect Patellofemoral mechanism which also places increased posterior force on the knee causing increased compression between the patella and the femur.
- A tight iliotibial band can exert an increased lateral force on the patella causing the patellofemoral dysfunction.
- Forefoot varus with compensatory rear foot valgus – foot pronation.
- Lower extremity limb length discrepancy.
- Tight hamstring can cause over work for extensor mechanism to maintain balance thereby causing muscle fatigue. Also, tight hamstring may lead to toe-out and foot pronation.
In the clinic, a complete assessment of lower extremity including the spine is the vital component for accurate diagnosis of patellofemoral dysfunction and hence to formulate the most effective treatment plan. The treatment of symptoms is never a proper management of patellofemoral pain rather may have a deleterious effect in a long term. With no pain or symptoms, the patients will continue their activities with biomechanical dysfunctions or other problems which may cause further serious injuries.
Manual and exercise therapy to improve muscle strength, flexibility, and active joint range of motion is the primary aspect of a treatment plan. The treatment plan needs to address the cause of mechanical dysfunction in a kinetic chain for a long-term effective management of the patellofemoral pain. Studies have shown that even with unilateral patellofemoral disorders, proprioceptive quality of both the knee is affected and reduced. Thus, proprioceptive training for knee or lower extremity is an inevitable part of the rehabilitation program.