pathologies

Knee

Patellar instability

treatment

The first dislocation is treated in the emergency department with a reduction followed by immobilization with a splint. This may be a plaster cast or even a removable splint.

Puncture of the knee is not the rule; early placement of an ice bladder reduces existing hemarthrosis (presence of blood in the knee). If the knee remains gonflé, we can achieve pain relief with evacuation puncture, with faster recovery of joint mobility.

Rehabilitation begins after about ten days.

A knee brace is prescribed.

Surgical techniques

Sectioning the external patellar fin

The patella is held in the middle of the trochlea by two ligaments. Sometimes, the lateral ligament is much stronger, causing the patella to move outwards. Sectioning this ligament (patellar aileron) can improve the centring of the patella.

I'm a fan of mini-arthroscopic surgery, which is easy to perform afterwards, with the patient leaving hospital the same day.

Internal myoplasty

It consists in strengthening the opposite ligament (medial patellar fin) with the help of the vastus medialis muscle, whose insertion is lowered to the level of the patella.

Medio patello-femoral ligament (MPFL) replacement

When this ligament, which opposes the external patellar fin, is completely torn, its replacement can be envisaged, often using a tendon graft. This procedure is often accompanied by sectioning of the external patellar fin.

Transposition of the anterior tibial tuberosity

If the patella is misaligned, we move its tibial attachment (the patellar tendon) with a bone fragment afin to allow re-axation of the patella. The detached tibial rod is fixed with screws that can be removed later.

Trochleoplasty

The trochlea of the femur is not deep enough, leading to instability of the patella. A new trochlea (the "rail" on which the patella slides) is created by removing the bone underneath.

Conclusion

This is a complex pathology with multiple causes: the choice of treatment and the indication for surgery are decided after further assessment, and must be carefully considered.

diagnosis

It's easy because you can see that the patella is out of place and deforming the knee. However, it is important to distinguish between a complete dislocation of the knee (between the tibia and the femur). Certain associated fractures must be ruled out.

An MRI scan is required to look for cartilage lesions and to confirm injury to the medio-patellofemoral ligament.

symptoms

The patella may dislocate, i.e. leave its usual place in relation to the rest of the joint; it always luxates outwards. When the patella is dislocated, the knee is completely locked in flexion, and the patient presents significant pain.

This is an orthopedic emergency, and the patella must be put back in place. The reduction procedure is always performed with the knee in extension. Sometimes, reduction occurs spontaneously, with the knee in extension. Ligament damage secondary to dislocation can lead to residual patellar instability.

Definition

The patella is a bone located on the anterior surface of the knee at the end of the tendon of the thigh muscle (quadriceps). The patella attaches to the tibia via the patellar tendon.

During flexion/extension, the patella slides up and down in a notch called the femoral trochlea.... The patella is above the trochlea when the knee is in extension. Knee flexion causes the patella to engage the trochlea.

The patella is held in place in the middle of the trochlea by several ligamentous attachments (patellar fins).

When the patella becomes overstretched, some of its attachments break and the kneecap becomes unstable.