Due to the fact that the patella acts as a “shield” for the knee joint, it can easily be fractured. For example, a direct fall on the knee is a common cause of patella fractures and fractures of this kind usually require surgical treatment.
The patella lies in front of the knee; more specifically, at the point where the tibia is joined to the femur. It protects the knee and connects the muscles of the anterior surface with the tibia. The lower femoral surface and the posterior surface of the patella are covered by articular cartilage. This helps to smooth the slide of the patella onto the femoral groove as the joint moves.
Patellar fractures account for 1% of all fractures. They are more common in people aged 20-50, while men are twice as likely to be affected as women.
TYPES OF FRACTURES
Patellar fractures vary in shape and severity. The bone can break at one level or more. The fracture line may be in the upper, middle or lower part of the patella. In some cases the fracture may be in more than one position on the patella.
STABLE FRACTURE: This fracture is not dislocated. The two segments of the broken bone are in contact with each other and are aligned. In this type of fracture the bones are healed in the correct position.
DISLOCATED FRACTURE: When a bone is fractured and dislocated, the segments of the fractured bone are separated and not aligned. This type of fracture usually requires surgery to be healed.
COMMINUTED FRACTURE: It is a very unstable fracture. The bone breaks into 3 or more pieces.
OPEN FRACTURE: In this case the skin is torn and the bone is exposed to the environment. This kind of injury causes much more damage to the surrounding tissues (muscles, ligaments). Open fractures are more likely to cause complications and require more time to heal.
They are usually caused by a direct hit, such as a fall from high altitude or a car accident. They can also occur indirectly; for example thigh muscles can contract so violently that they cause a patellar fracture.
The main symptoms of a patellar fracture include pain and swelling in the front surface of the knee. Additional symptoms are:
- Inability to extend the knee
- Inability to walk
After obtaining a medical history, the treating physician shall perform a clinical examination of the affected leg. Fractured ends can easily be located under the skin, especially if the fracture is displaced. The orthopedist will still check for the presence of hematomas within the knee joint caused by fracture bleeding.
Simple radiographs are the most common diagnostic tests. It is the most useful test for depicting dense knee structures, such as bones. Rarely can one have two bones by birth in the position of the patella and this is called bipartite patella. It is a normal anatomical variant and can be misinterpreted as a fracture. It is often observed on both knees at the same time, so the orthopedist may recommend x-rays on both knees.
If the pieces of broken bone are not dislocated by the severity of the injury, surgery may not be required. Splints can be used to keep the knee straight. They will help to properly align the fractured bones for healing purposes. The knee should not be charged with weight until the fracture heals, i.e. 6-8 weeks after injury. The use of accessories, such as crutches, is encouraged during this time.
In the case of surgical treatment of patellar fractures, the fractured bones remain at a distance from each other due to contraction of strong muscles that has a displacement effect.
PREPARATION FOR SURGERY
If there is no open wound around the fracture, the doctor may recommend waiting until the skin has “calmed down” (reduction of edema and hematoma until surgery). Open fractures expose the bone to the environment, so they require urgent treatment with surgical washout and restoration.
The type of surgery you will need depends on the type of injury. Preoperatively, the orthopedist will discuss the options for surgery with the patient, as well as the possible complications.
TRANSVERSE FRACTURE: Fractures of this kind are usually realigned with the help of screws and wires. This method is best applied to fractures located near the center of the patella. When the fracture is closer to the circumference of the bone, it may be over-compressed with this method. Another method is to repair the fracture by using small screws and wires, which need to be removed 2 years postoperatively.
COMMINUTED FRACTURE: In some cases, either the top of the patella or the bottom can break into several pieces. In the case where the very small size of the pieces does not allow for osteosynthesis, they are removed and the remaining bone is restored accordingly, placing the patellar tendon in its anatomical position.
Complete removal of the patella bone is the last resort and it is rarely used when the bones are too small and cannot be rescued.
The length of time required to recover from a patellar fracture depends on the severity of the injury and whether it was surgically treated. Depending on the case, it will be decided when it is best for the patient to charge their knees with weight and return to their daily activities.
Whether the fracture was treated surgically or not, rehabilitation plays a very important role in the outcome of the injury and the return to its former state. Immobilizing the lower limb with a splint can lead to stiffness and weakness of the femoral muscles. Specific exercises will help to strengthen and restore the range of motion of the knee. The treating physician will instruct you when it is time to start charging your leg. Initially, charging only involves contact with the ground, and this will gradually increase to the point of full charging, depending on the stage of healing.
POST-TRAUMATIC ARTHRITIS: Patellar fractures often injure the articular cartilage on the articular surface of the patella, which can lead to the development of osteoarthritis. Significant arthritis is observed in 1 in 5 patients. It is usually mild arthritis.
MUSCLE WEAKNESS: The permanent weakness of the quadriceps muscle in the anterior thigh is another long-term result. In addition, some loss of movement is expected, both in extension and in flexion. However, this loss of motion range is not significant enough to lead to a disability.
CHRONIC PAIN: Chronic pain is a common symptom of surgically treated patella fractures.
LIFE CHANGES: Your doctor may recommend some changes to your daily lifestyle to protect your knee and prevent future problems. This may include avoiding deep-seated exercises or repeated knee flexion and extension.