To understand osteoarthritis of the patellofemoral joint (retropatellar osteoarthritis), you should know the anatomy of the knee joint. The knee joint is the largest joint in the human body and consists of three main bones:
- the thigh bone (femur)
- the shin bone (tibia) and
- the kneecap (patella)
It is a complex hinge joint that enables movements such as flexion and extension.
Anatomy of the knee joint @ bilderzwerg /AdobeStock
The patellofemoral joint consists of the kneecap (patella) and the gliding path of the thigh bone (trochlea). The patella serves to transmit the force of the powerful extensor apparatus and increases its lever arm. It is therefore essential for powerful extension of the knee joint (e.g. when climbing stairs).
The development of retropatellar osteoarthritis is often multifactorial and has various causes, including
- Age: Age is a major factor in the development of joint disease. With increasing age, the quality of the joint cartilage decreases, which increases the risk of osteoarthritis.
- Overuse: Repeated and prolonged strain on the knee joint during certain sports or occupational activities increases the risk of osteoarthritis.
- Anatomical factors: Individual anatomy also often plays a role. A shallow patellar joint gap (patellar dysplasia) or unfavorable alignment of the kneecap increase the risk of isolated osteoarthritis in the patellofemoral joint.
- Genetics: Genetic factors can contribute to whether someone is more susceptible to developing joint diseases such as retropatellar osteoarthritis.
- Knee pain: Pain is the leading symptom of retropatellar osteoarthritis. It often occurs at the front of the knee joint, behind or around the kneecap and can worsen with movement. Climbing stairs is particularly painful.
Retropatellar osteoarthritis manifests itself in a variety of symptoms that can vary from patient to patient.
The most common symptoms include
- Stiffness: patients may experience stiffness in the knee joint, especially after prolonged periods of rest or after waking up in the morning.
- Swelling: Swelling around the knee joint may occur, especially after intense exercise.
- Crunching or cracking: Crunching or cracking in the knee joint, known as crepitations, especially during movement, is a common symptom of retropatellar osteoarthritis.
- Restricted mobility: The mobility of the knee joint may be restricted, making walking and climbing stairs more difficult.
The diagnosis of retropatellar osteoarthritis requires a thorough examination and imaging.
Here are the common diagnostic procedures:
The doctor will first take a detailed medical history to gather information about the symptoms and medical history. A thorough physical examination of the knee, including movement tests and tenderness, is also crucial.
X-rays, MRI (magnetic resonance imaging) and CT (computed tomography) scans check the condition of cartilage, bone and other structures.
These examinations help the doctor to determine the severity of the osteoarthritis. They also allow conclusions to be drawn about the causes of the osteoarthritis.
In some cases, an arthroscopy of the knee is necessary. Arthroscopy is a minimally invasive surgical procedure in which doctors insert a tiny camera into the knee joint. This allows them to assess the condition of the cartilage directly. However, this procedure is becoming less and less important.
The aims of treatment are
- To relieve pain
- to improve the function of the knee and
- to slow down the progression of the disease
The choice of treatment depends on
- Severity of the osteoarthritis
- Reasons for the development and
- Individual needs of the patient
Conservative treatment options include:
Targeted exercises and physiotherapy measures strengthen the muscles and improve mobility.
The administration of anti-inflammatory medication or painkillers can relieve pain.
In overweight patients, weight loss can reduce the pressure on the knee joint.
Injection therapies include:
These hyaluronic acid injections can improve joint lubrication and temporarily relieve pain.
In some cases, injections containing corticosteroids can suppress inflammatory processes.
Surgical treatment options include
- Arthroscopic debridement:
Is a minimally invasive surgery in which doctors remove loose or damaged cartilage. This reduces friction in the joint and relieves symptoms.
This can improve pain and stiffness, but is more of a temporary solution and does not slow down the progression of osteoarthritis.
This surgery is suitable for correcting the alignment of the knee. Doctors reposition the bones around the knee joint. The pressure on the kneecap is reduced and the load is distributed evenly. This can be helpful for certain anatomical misalignments, especially knock-knees (valgus deformity).
In younger patients with limited cartilage damage, a cartilage transplant is useful. Here, doctors transplant healthy cartilage from another part of the knee joint or from a donor. In this way, they replace the damaged cartilage. This procedure can significantly improve knee function, but is technically demanding and not suitable for all patients.
- Partial or total endoprosthesis:
In advanced stages of retropatellar osteoarthritis, implantation of a partial or total endoprosthesis may be necessary. With a partial endoprosthesis (patellofemoral prosthesis), doctors only replace the kneecap component.
This is a particularly good procedure for young patients with isolated disease of the patellofemoral joint. Unaffected parts of the knee joint are spared, while the total endoprosthesis replaces the entire knee joint.
Partial and total knee replacements are extensive operations that require a longer recovery period. However, they offer significant pain relief and restoration of mobility.
After surgical treatment of retropatellar arthrosis, rehabilitation is crucial. Physiotherapy plays an important role in regaining mobility and strength in the knee joint.
An individualized rehabilitation program, including exercises to strengthen the muscles and mobilize the joint, is designed by the physiotherapist in charge.
It is also important to follow the doctor's instructions regarding weight-bearing and activity restrictions after the operation. In most cases, it can take several months for the patient to regain full knee function.
Retropatellar osteoarthritis is a painful joint disease in the knee joint. It significantly impairs the quality of life of those affected.
The causes are varied and the symptoms can vary from patient to patient. Diagnosis is based on a thorough examination and imaging.
Treatment options range from conservative measures and injection therapies to various surgical procedures. The choice of appropriate therapy depends on the patient's individual situation.
Timely diagnosis and appropriate treatment help to alleviate pain and improve quality of life.
It is important to seek advice from an experienced orthopaedic surgeon to determine the best treatment options for you. Only experienced arthroplasty specialists perform partial joint replacement of the patellofemoral joint (patellofemoral prosthesis).
