Table of ContentsView AllTable of ContentsTypesSymptomsCausesDiagnosisTreatment
Table of ContentsView All
View All
Table of Contents
Types
Symptoms
Causes
Diagnosis
Treatment
Akneecap injurycan happen from a blow to the knee or a fall. Some injuries can also occur due to overuse. When you injure your kneecap—also called your patella—there may be damage to the surrounding soft tissues, such as a patellar tendon tear, or a fracture to the bone.
Symptoms may include pain, swelling, a feeling of instability, or that the joint is locked. Some types of injuries can be treated with bracing and rehabilitation exercises, but others may need surgery.
This article discusses the different types of kneecap injuries, their symptoms, and how they may be treated.
Types of Kneecap Injuries
The patella is part of the knee joint, along with the tibia (shin bone) and femur (thigh bone). It is wrapped in the patellar tendon, which connects thequadriceps muscleof the thigh to the tibia below the knee joint.
Sitting at the front of the knee joint, the patella tracks in a groove at the end of the femur (the patellofemoral joint) and enhances the extension of the knee.
The most common types of kneecap injuries include the following.
Verywell / Kelly Miller
Signs of a Kneecap Injury
Acute injuries of the kneecap will produce symptoms common to other soft tissue and bone injuries, such as pain, swelling, and deformity. You often will have functional symptoms as well.
Common symptoms include the following.
Injuries to the patella usually result in difficulties in moving the knee, walking, or running. The patella is important functionally because it increases the leverage of the knee joint and the strength of extension of the leg.
A dislocated kneecap may spontaneously pop back into place. This can produce bruising and damage to the soft tissues. You should see your healthcare provider as soon as possible for further assessment even if there doesn’t seem to be damage.
Prepatellar bursitisor patellar bursitis (inflammation and swelling of the sac around the knee) can be a complication of traumatic injuries to the patella, either due to the injury itself or infection following an injury. In addition to swelling at the front of the kneecap, the area may be tender and warm.If bursitis is due to infection, there may be fever and chills as well.
Knee Pain: When to See a Healthcare Provider
Kneecap injuries can occur as a result of trauma, sports activities, or anatomical problems within the knee joint.
Accidents and Trauma
The location of the patella at the front of the knee makes it vulnerable to fracture, dislocation, or tendon tears during falls, blows to the knee, or sharp impacts such as with the dashboard in a car accident.
Traffic accidents are the cause of 78.3% of patella fractures. Work-related accidents and accidents in the home account for 13.7% and 11.4%, respectively.
If a person hasosteoporosis, the weakness of the bone may increase the risk of a patella fracture from a minor fall or blow to the knee.Pathologic patella fracturesmay also be seen in cases of bone infection or a bone tumor.
Sports Injuries
Kneecap injuries can also happen during sudden movements, such as those that may be made during sports activities—for example, when the foot is planted and the torso rotates swiftly during a swing of a baseball bat.
You can also tear your patellar tendon when landing from a jump with the knee bent and foot planted. You may be predisposed to a patellar tendon tear if you already have patellar tendonitis.
A sudden contraction of the quadriceps can result in a patella fracture.This can happen when you land a jump from a height, although it is uncommon.
Anatomical Differences
Variations in the anatomy of the knee can contribute to the risk of injury, especially when it comes to instability or dislocation.
Some people are born with an uneven or shallow femoral groove. This compromises the stability of the patellofemoral joint and can result in the kneecap being displaced due to seemingly normal activities—not just a blow or a fall.
Some people may be more prone to kneecap dislocations because they have looser ligaments.Kneecap dislocations are most commonly reported in adolescent females.
Anatomy of the Knee
Depending on the circumstances, you may see your primary healthcare provider or seek emergency treatment. Urgent assessment is best if the knee injury was sustained during a fall or accident, or if a kneecap dislocation has not popped back into place.
The healthcare provider will take your history and report of what led to the knee pain, symptoms at the time (such as hearing a pop), and your current symptoms.
Examination
During the physical examination, the healthcare provider will observe whether you are able to walk and bend or unbend your knee. They will palpate the knee to see if there are areas that show defects, displacement, or localized pain. A visual exam of the knee assesses whether there is swelling, deformity, or obvious displacement.
Manual tests and maneuvers are used to assess damage to the kneecap or tendons, including trying to extend your knee against gravity. Thestraight leg raise testcan reveal disruption of the extensor mechanism, which includes the quadriceps tendon, patella, and patellar tendon.
Imaging and Labs
Several different tests may be done to help diagnose your injury. These include:
Differential diagnoses may include arthritis andchondromalacia patellae(runner’s knee).These can be the source of knee pain without a traumatic incident, or they may be present in addition to other patellar injuries.
Treatment of these various acute kneecap conditions depends on the diagnosis. However, there are some general guidelines that can be followed. Your healthcare provider will advise you based on your diagnosis.
Home Remedies
Reduction
A kneecap dislocation needs to be reduced (a procedure in which the kneecap is returned to the femoral groove). If this doesn’t happen spontaneously, the healthcare provider will do the reduction as soon as possible.
A reduction might require pain medication so the provider can extend the leg and manipulate the kneecap. Often, it will snap back into place with gentle pressure when the leg is extended.
Immobilization
Any kneecap injury may need to be immobilized with a cast, splint, or brace to allow healing of the bone, tendon, or other soft tissues. Your healthcare provider will recommend which of these is appropriate, if any.
They may also recommend you not bear weight on the affected leg during the immobilization period. You might need to use crutches or other mobility aids until this period is complete.
Surgical Procedures
A fractured kneecap may require surgery if any pieces of bone are out of place.This often means installing wires, screws, plates, or pins to unite the bone pieces and keep them in place while you are healing.
Complete patellar tendon tears often require surgical repair.Sutures are placed in the tendon and anchored to holes or surgical anchors on the patella. This can be performed as an outpatient surgery.
There are several surgicalkneecap stabilizationprocedures that can be done for recurring patella dislocations or subluxations. Dislocations are often associated with damage to the medial patellofemoral ligament, which holds the kneecap in place. Surgery can be performed to repair or reconstruct the ligament.
Weight-Bearing Restrictions and Activity After Surgery
Physical Therapy
For any kneecap injury, physical therapy is likely to be recommended after the initial inflammation has subsided and immobilization is no longer needed. Immobilization itself will result in stiffness and loss of muscle strength. Your physical therapist will work to restore the knee’s range of motion and muscle strength.
If weight-bearing is not allowed, you will gradually progress to being able to support weight on the injured leg. This can start with toe-touch weight bearing for a couple of weeks, then progresses to 50% weight bearing, and finally full weight bearing after four to six weeks, depending on your type of injury.
The function of the knee joint requires balancing the strength of the muscles around the knee joint. Most importantly, the quadriceps andhamstring muscle groupsshould be flexible and balanced. Your physical therapist will recommend specific exercises depending on your condition.
Summary
Kneecap injuries can happen when you fall on your knee or receive a blow to the knee. Some injuries may occur over time due to overuse of the knee. These injuries can cause pain, swelling, and difficulty walking.
Kneecap injuries are usually diagnosed with an exam and imaging tests such as an x-ray. Minor injuries can be treated at home with rest, while more serious injuries may require a cast, brace, or surgery.
10 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Orthopaedic Surgeons.Patellar tendon tear.American Academy of Orthopaedic Surgeons.Unstable kneecap.Koh JL, Stewart C.Patellar instability.Orthop Clin North Am. 2015;46(1):147-57. doi:10.1016/j.ocl.2014.09.011American Academy of Orthopaedic Surgeons.Patellar (kneecap) fractures.Bunt CW, Jonas CE, Chang JG.Knee pain in adults and adolescents: The initial evaluation.Am Fam Physician. 2018;98(9):576-585American Academy of Orthopaedic Surgeons.Prepatellar (kneecap) bursitis.Gwinner C, Märdian S, Schwabe P, Schaser KD, Krapohl BD, Jung TM.Current concepts review: Fractures of the patella.GMS Interdiscip Plast Reconstr Surg DGPW. 2016;5:Doc01. doi:10.3205/iprs000080American Academy of Orthopaedic Surgeons.Patellar dislocation and instability in children (unstable kneecap).Jaglarz D, Mazurek T.Symptomatology and diagnosis. Patellofemoral pain.Chir Narzadow Ruchu Ortop Pol. 2017;82(4):145-9.Yeung M, Leblanc MC, Ayeni OR, Khan M, Hiemstra LA, Kerslake S, Peterson D.Indications for medial patellofemoral ligament reconstruction: A systematic review.J Knee Surg. 2016;29(7):543-554. doi:10.1055/s-0035-1564730
10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Orthopaedic Surgeons.Patellar tendon tear.American Academy of Orthopaedic Surgeons.Unstable kneecap.Koh JL, Stewart C.Patellar instability.Orthop Clin North Am. 2015;46(1):147-57. doi:10.1016/j.ocl.2014.09.011American Academy of Orthopaedic Surgeons.Patellar (kneecap) fractures.Bunt CW, Jonas CE, Chang JG.Knee pain in adults and adolescents: The initial evaluation.Am Fam Physician. 2018;98(9):576-585American Academy of Orthopaedic Surgeons.Prepatellar (kneecap) bursitis.Gwinner C, Märdian S, Schwabe P, Schaser KD, Krapohl BD, Jung TM.Current concepts review: Fractures of the patella.GMS Interdiscip Plast Reconstr Surg DGPW. 2016;5:Doc01. doi:10.3205/iprs000080American Academy of Orthopaedic Surgeons.Patellar dislocation and instability in children (unstable kneecap).Jaglarz D, Mazurek T.Symptomatology and diagnosis. Patellofemoral pain.Chir Narzadow Ruchu Ortop Pol. 2017;82(4):145-9.Yeung M, Leblanc MC, Ayeni OR, Khan M, Hiemstra LA, Kerslake S, Peterson D.Indications for medial patellofemoral ligament reconstruction: A systematic review.J Knee Surg. 2016;29(7):543-554. doi:10.1055/s-0035-1564730
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Orthopaedic Surgeons.Patellar tendon tear.American Academy of Orthopaedic Surgeons.Unstable kneecap.Koh JL, Stewart C.Patellar instability.Orthop Clin North Am. 2015;46(1):147-57. doi:10.1016/j.ocl.2014.09.011American Academy of Orthopaedic Surgeons.Patellar (kneecap) fractures.Bunt CW, Jonas CE, Chang JG.Knee pain in adults and adolescents: The initial evaluation.Am Fam Physician. 2018;98(9):576-585American Academy of Orthopaedic Surgeons.Prepatellar (kneecap) bursitis.Gwinner C, Märdian S, Schwabe P, Schaser KD, Krapohl BD, Jung TM.Current concepts review: Fractures of the patella.GMS Interdiscip Plast Reconstr Surg DGPW. 2016;5:Doc01. doi:10.3205/iprs000080American Academy of Orthopaedic Surgeons.Patellar dislocation and instability in children (unstable kneecap).Jaglarz D, Mazurek T.Symptomatology and diagnosis. Patellofemoral pain.Chir Narzadow Ruchu Ortop Pol. 2017;82(4):145-9.Yeung M, Leblanc MC, Ayeni OR, Khan M, Hiemstra LA, Kerslake S, Peterson D.Indications for medial patellofemoral ligament reconstruction: A systematic review.J Knee Surg. 2016;29(7):543-554. doi:10.1055/s-0035-1564730
American Academy of Orthopaedic Surgeons.Patellar tendon tear.
American Academy of Orthopaedic Surgeons.Unstable kneecap.
Koh JL, Stewart C.Patellar instability.Orthop Clin North Am. 2015;46(1):147-57. doi:10.1016/j.ocl.2014.09.011
American Academy of Orthopaedic Surgeons.Patellar (kneecap) fractures.
Bunt CW, Jonas CE, Chang JG.Knee pain in adults and adolescents: The initial evaluation.Am Fam Physician. 2018;98(9):576-585
American Academy of Orthopaedic Surgeons.Prepatellar (kneecap) bursitis.
Gwinner C, Märdian S, Schwabe P, Schaser KD, Krapohl BD, Jung TM.Current concepts review: Fractures of the patella.GMS Interdiscip Plast Reconstr Surg DGPW. 2016;5:Doc01. doi:10.3205/iprs000080
American Academy of Orthopaedic Surgeons.Patellar dislocation and instability in children (unstable kneecap).
Jaglarz D, Mazurek T.Symptomatology and diagnosis. Patellofemoral pain.Chir Narzadow Ruchu Ortop Pol. 2017;82(4):145-9.
Yeung M, Leblanc MC, Ayeni OR, Khan M, Hiemstra LA, Kerslake S, Peterson D.Indications for medial patellofemoral ligament reconstruction: A systematic review.J Knee Surg. 2016;29(7):543-554. doi:10.1055/s-0035-1564730
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