Introduction
The patellofemoral joint (the joint between the kneecap and femur) is a complex joint where stability issues (part 1), cartilage injuries, and osteoarthritis pain problems (part 2), as well as pain issues (part 3), often arise. These issues should be properly distinguished from each other, as they each warrant a different approach. It’s important to note that the kneecap undergoes up to 8 times the body weight when climbing stairs, descending, jumping, and landing. Additionally, during deep flexion or squatting, an enormous amount of force is transmitted through this joint, hence the frequent problems.
Part 1
Patella Dislocation and Instability
Patellar dislocation and instability typically first manifest in young individuals between the ages of 14 and 24. The underlying cause is an abnormality in the shape of the femur and patella, where the trochlea (the groove in the femur into which the kneecap should slide) is flattened, a condition known as trochleodysplasia. This allows the kneecap to dislocate laterally or more easily. In certain cases, the kneecap may be positioned too high (patella alta), the attachment point of the patellar tendon on the tibia may be too lateral (increased TAGT distance), and/or the kneecap may be tilted too much (patellar tilt). The more severe these abnormalities are in the knee, the earlier the first dislocation is likely to occur. Occasionally, a dislocation can happen to someone without risk factors during sports where a direct blow is delivered to the kneecap. During a patellar dislocation, the Medial PatelloFemoral Ligament (MPFL) always tears, which naturally increases the risk of a second patellar dislocation. In recent years, the surgical approach for patellar dislocations has therefore focused on MPFL ligament reconstruction with excellent results. In some patients, a cartilage injury may occur during a dislocation. However, most of these injuries do not require treatment as the restoration of stability through MPFL reconstruction often leads to spontaneous healing of the cartilage injury.
MPFL Reconstruction
An autologous tendon (usually the gracilis or semitendinosus) is typically utilized for the reconstruction of the MPFL ligament. This tendon is anchored to both the femur and the kneecap, preventing the kneecap from dislocating outwards. Because this reconstruction is four times stronger than the original ligament, the stability of the kneecap will be adequately restored in most patients.
Concomitant Surgery
In certain instances, when the kneecap is excessively elevated (patella alta), achieving adequate results with MPFL reconstruction alone may be challenging. In such cases, it becomes necessary to lower the position of the kneecap through a tibial tuberosity transfer. Alternatively, if the attachment point of the kneecap to the tibia is too lateral, it may require medialization. In severe cases of trochleodysplasia, a trochleoplasty might be recommended. The decision for additional surgery should be made on an individual basis in consultation with your surgeon.
Part 2
Cartilage Lesions and Osteoarthritis
Cartilage injuries at the level of the kneecap and trochlea seldom result from obvious trauma (such as a fall on the knee or patellar dislocation), but rather frequently stem from microtrauma. These microtraumas often accumulate from minor but prolonged overuse, ultimately leading to cartilage injuries. This is also the reason why most cartilage injuries are observed at a somewhat older age, typically between 35 and 45 years. However, most patients seek treatment when the entire cartilage has deteriorated, resulting in knee osteoarthritis. In older age, treatment for cartilage lesions is generally conservative, involving physiotherapy, as well as injections with hyaluronic acid or cortisone. In specific cases, there may be a surgical indication for procedures like arthroscopy, cartilage treatment, or procedures to realign or alleviate pressure on the kneecap (such as the Fulkerson Procedure). In cases of osteoarthritis, prosthesis surgery may be necessary. Typically, patients requiring knee prosthesis surgery are slightly younger (between 50 and 60 years old) than the more conventional prosthesis patient (65 years and older).
Part 3
Anterior Knee Pain
Anterior knee pain, or pain in the front of the knee joint, is a common issue, particularly in young girls and ladies (aged 12-25 years). There is no history of obvious instability, nor are there any apparent abnormalities visible on imaging. These patients should be treated conservatively through education, targeted physiotherapy, and potentially with the addition of nutritional supplements. There is no surgical indication in this case. Although often persistent, most complaints tend to spontaneously resolve after the age of 25…