A displaced patella occurs when the kneecap (patella) slips out of its groove on the thigh bone (femur). Without the kneecap in its proper position, the knee will not be able to lock into place or move across its normal range of motion.
- Injuries typically cause very severe pain and usually require medical attention to correct.
- A dislocated patella is usually the result of an activity in which the knee is forced out of its correct position during running and cutting movements.
- Often, the doctor will be able to reposition the knee cap by manipulating the joint. However, surgery may be necessary to restore the normal function of the knee.
- Some individuals experience repeated dislocations which can be popped back into place. Though these repeated dislocations may be less painful, medical attention should be sought to correct the recurring injury.
Signs and Symptoms
- Excruciating pain in the knee at the time of injury
- A feeling of unsteadiness or the tendency for the knee to “give way”
- Immediate swelling of the knee followed by bruising
- Loss of function and severe pain when attempting to move the knee
- A visible deformity in the knee if the dislocated bones have locked into place (bones may reposition themselves and leave no deformity, though damage has still occurred)
- Numbness or partial paralysis below the dislocation as a result of pressure pinching or cutting blood vessels and nerves
Contact the Doctor if …
- The patient has the signs and symptoms of Patella Malalignment/Dislocation.
- The patient has signs of infection.
Causes of Injury
- A dislocated patella is typically the result of sudden changes in direction while running or jumping.
- Any force which causes the knee joint to rotate may displace the patella from its natural position.
- Injuries may also occur from a direct blow to the knee.
- In rare cases, the patella can dislocate after a powerful muscle contraction in which the patella is dislocated by the strong pull of the quadriceps (thigh) muscles.
- Patella dislocations are common in activities like basketball, soccer and football which involve running, sudden turning and stopping.
Expectations of Recovery
- With proper care, most patients can expect a full recovery from a dislocated patella.
- After treatment to correct the dislocation, patients may expect the joint to be supported with a brace for 6 to 8 weeks.
- Depending upon the severity of the damage caused by the dislocated patella, injured ligaments and surrounding structures will likely take a minimum of 6 weeks to completely heal.
Medical Details
The knee cap (patella) acts as a fulcrum to lessen friction and provide efficient flexion and extension of the knee. A groove on the front of the thigh bone (femur) allows the kneecap to slide up and down while the joint is in motion. Some individuals have more shallow grooves in the thigh bone which may predispose them to dislocation injuries. Also, those individuals that have suffered repeated knee injuries or have abnormal anatomy of the knee may be at greater risk for dislocation.
Young adults are prone to the injury because of increased flexibility (and ligamentous laxity) which allows joints to move more easily, sometimes allowing the knee to move into untoward positions. Young females are particularly at risk because of their limberness. This risk from increased flexibility is compounded by an increased Q angle (when the hips are much wider than the knees) and a somewhat “knock kneed” gait while running or playing sports. This bent-in angle of the knee allows the kneecap to more easily move out of the femoral groove, making it more susceptible to dislocation.
Diagnosis
The initial dislocation commonly results in extreme pain. The dislocation is often visible, although the doctor will also check for additional injuries that may have occurred with the dislocation. A review of the patient’s medical history will check for similar injuries in the past.
Treatment Options
A dislocated patella will not necessarily require surgery for a full recovery. Differences in the severity and mechanism of injury will affect the treatment decision, as will the degree of athletic activity that the patient wishes to pursue after treatment. The patella itself may be manually shifted back into place by a doctor, other dislocations will demand surgery to correct.
However, patella dislocations may also cause collateral injuries. These are injuries that are caused as the patella is dislocated, such as bone fragmenting, slivers of which may become lodged in the joint. The severity of these surrounding injuries may range from minor disruptions to very damaging tears of the internal structure and surrounding ligaments.
Non-Surgical Treatment: Conservative Treatment of Patella Malalignment
- Patients will usually be required to keep the knee stabilized for up to six weeks. The doctor will prescribe either a brace or splint to prevent further damage.
- After the splint or brace is removed, physical therapy will be initiated to restore strength and correct alignment problems or muscle imbalances that may have contributed to the dislocation.
- The goal of therapy is to re-establish a full range of motion in the knee with proper alignment or tracking of the patella.
- Ongoing therapy rehabilitates the quadriceps and hamstrings, the muscles surrounding the knee which add strength and stability to the joint.
- Therapists may recommend changes in activity and specialized bracing to support the knee during movement or while it is under stress.
Non-Surgical Product Considerations
Knee: Support
A knee support is a sleeve-like support that fits firmly around the knee. The support is used to reinforce the joint during motion and provide compression to aid healing and reduce pain and swelling. Patients suffering from knee strains or inflammation will usually be directed to use a support during daily activities.
The thin and flexible construction of the support allows for normal movement of the knee and also allows the support to be worn under loose fitting clothing. To prevent harmful pressure to certain structures, the support applies differing compression around the knee. The sides of the joint receive intermittent pressure to help stimulate blood flow while the rear of the support fits relatively loose to prevent constriction of circulation. The kneecap is aided in positioning, but remains free of compression to allow its natural movement.
Knee supports can be used to treat:
- Strains
- Sprains
- Inflammation
- Chondromalacia patella
Patella Supports
Orthotics
An orthotic insert fits inside a shoe and helps position the foot in an anatomically correct position while walking, running or jumping. Frequently, abnormal foot motion and gait occurs as a result of over-pronation of the foot; most orthotics are used to treat this condition. Over-pronation is a tendency to roll the foot onto the inner edge, loading the inside of the foot and leaving the outer edge almost weightless. A professionally made orthotic insert will exactly contour to the bottom of the foot, and can compensate for over-pronation or other abnormal foot mechanics.
One of two construction methods may be used to create an orthotic; one utilizes a plaster mold of the entire foot to make a moderately rigid insert, the other utilizes a foam impression of the bottom of the foot, creating a more flexible insert. In either case, the finished product must be tilted with small wedges, while other accommodations are made to protect sensitive areas of the foot. The choice of orthotics and design will vary according to the expected use, foot type and body weight.
Orthotics can be used to treat:
- Abnormal foot mechanics
- Patella dislocation or maltracking
- Patellar tendonitis
- General knee pain
- Ankle instability
