What Is Patellofemoral Osteoarthritis?
Patellofemoral osteoarthritis is essentially the degeneration of the joint between the kneecap and the femur (thigh bone).
Patients primarily complain of pain beneath the kneecap. This pain intensifies during activities such as bending the knee, squatting, and climbing stairs. Symptoms worsen as daily activities increase.
Diagnosis typically involves a physical examination and follow-up X-rays. Your doctor may request MRI imaging if necessary.
Patellofemoral osteoarthritis usually occurs in three different scenarios:
- Osteoarthritis after instability: This often occurs after dislocations of the kneecap and knee. Continuous loading on the front of the knee due to torn cruciate ligaments can lead to osteoarthritis in the kneecap.
- Osteoarthritis after trauma: This can develop from damage to the cartilage following a direct injury to the knee, which progresses over time.
- Overuse osteoarthritis: This results from excessive strain on the kneecap, leading to progressive thinning of the cartilage.
Treatment
The initial treatment for patellofemoral osteoarthritis involves rehabilitating the muscles around the knee and avoiding movements that cause pain. Patients are advised to refrain from activities like squatting and climbing stairs that exacerbate pain. Strengthening the quadriceps muscles and ensuring flexibility in the hamstrings help the knee joint move smoothly and fully. Simple analgesics can be beneficial in treatment.
In cases of moderate osteoarthritis, intra-articular steroid injections may alleviate symptoms.
For overweight patients, weight management can significantly reduce pain and slow disease progression.
Physical therapy can also be helpful for patients unable to perform necessary exercises at home.
If pain persists despite these measures, surgical options may be considered. The most significant among these is patellofemoral arthroplasty.
During patellofemoral arthroplasty, the lower joint surface of the kneecap is replaced with a polyethylene piece, and the corresponding surface is replaced with a very thin metal surface. This removes damaged tissue that causes pain and catching sensations from the joint.
If there are additional issues such as alignment problems or ligament insufficiency, these can also be corrected during the same surgery.
This surgery yields excellent results, particularly in cases of instability and trauma-related osteoarthritis, providing results comparable to total knee replacement. However, patellofemoral arthroplasty is performed through a much smaller surgical incision than total knee replacement, allowing for quicker rehabilitation. Patients often achieve very satisfactory results for many years and can easily transition to total knee replacement if necessary.
What Causes Patellar Instability?
The ability of the kneecap to move within the groove opposite it depends on various factors. Any disruption in these factors can lead to a dislocation of the kneecap.
These include:
- The groove in the femur being shallow or absent
- Loose connective tissue or hyperelastic joints
- Direct trauma to the knee joint during a fall, sports injury, or accident
- Additionally, some individuals are more prone to kneecap dislocation.
- Women, in particular, have looser connective tissue, leading to a higher incidence of kneecap dislocation. Furthermore, sudden changes in direction (pivoting) in contact sports (such as football and basketball) increase the likelihood of dislocation.
- Conditions such as cerebral palsy, Down syndrome, and Ehlers-Danlos syndrome also increase the risk of kneecap dislocation.
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