ABOUT
Patella (kneecap) dislocations are commonly seen in day to day practise. They usually occur in adolescents or young adults with contact or noncontact twisting injuries with the knee close to full extension. Almost always, the dislocation occurs with the patella dislocating to the outer side of the knee. Reducing the patella back in place usually happens with straightening the knee and gently pushing it back into place.
The patellar dislocation results in the rupture of a ligament on the inner side of the knee called the MPFL(medial patellofemoral ligament) that keeps the kneecap in center of knee.
Deficient MPFL can lead to recurrence of the dislocation even with trivial trauma. Less common factors such as altered limb alignment, flattening of the grove underlying the patella(trochlea dysplasia), Patella alta (relatively higher position of the patella) can also cause recurrence.
SYMPTOMS AND INVESTIGATIONS
- Giving way of the knee during dancing or trivial fall/direct impact are common presenting features.
- Occasionally, this injury results in fracture of a bony/cartilage fragment that causes locking sensation in the joint.
- X Rays such as Alignment view, Lateral & Skyline view at 30 flexion,
- MRI scan with or without CT are essential for assessing predisposing factors for recurrent patella dislocation.
TREATMENT
In general, the initial treatment of most patellar dislocations is nonoperative with a well-focused rehabilitation program.
In those patients who have recurrent dislocations, the recommended treatment is surgery to stabilise the knee to the center of knee.
This includes strengthening VMO(vastus medialis oblique) muscle exercise, that lies on the inner side of the knee with gradual knee bending and weight bearing
First time dislocators:
Patients who require surgery even after a single dislocation are those in whom a fragment gets separated from the patella that requires fixation/ removal using arthroscopy/mini open technique.
Recurrent dislocators:
Surgery involves a diagnostic visualisation of the knee joint using an arthroscope, assessment of the movement of the knee cap during knee bending & reconstruction of the Medial Patellofemoral ligament . This is done using a donor graft, usually a hamstring muscle graft from the back of the knee. The graft is prepared and fixed to the kneecap and the thigh bone using implants called suture anchors.
It is also necessary to address underlying pathologies like altered knee alignment, flattened grove & patella alta simultaneously during MPFL reconstruction to prevent recurrence.
