This is one of my favourite subject due to the shear complexity and variability in causation and management of this problem.

Many a times the problem is complex and multifactorial requiring detailed and thorough clinical and radiological assessment. Dr Sabnis has a special interest in managing this problem and has done multiple surgeries for unstable patella, including publishing articles on this.

Complex surgeries such as trochleoplasty, derogation osteotomy, tibial tubercle transfer, MPFL reconstruction can be required in isolation or in combination.

Causes

The kneecap connects the muscles in the front of the thigh to the shinbone (tibia). As you bend or straighten your leg, the kneecap is pulled up or down. The thighbone (femur) has a V-shaped notch (femoral groove) on front to accommodate the moving kneecap. In a normal knee, the kneecap fits and moves smoothly in the groove.

But if the groove is uneven or too shallow, the kneecap could slide off, resulting in a partial or complete dislocation. A sharp blow to the kneecap, as in a fall, could also pop the kneecap out of place.

Symptoms

• Knee buckles and can no longer support your weight.
• Kneecap slips off to the side
• Knee catches during movement
• Pain in the front of the knee that increases with activity
• Pain when sitting
• Stiffness
• Creaking or cracking sounds during movement
• Swelling

Treatment

If the kneecap has been completely dislocated out of its groove, the first step is to return the kneecap to its proper place. This process is called reduction. Sometimes, reduction happens spontaneously. Other times, your doctor will have to apply gentle force to push the kneecap back in place.

A dislocation often damages the underside of the kneecap and the end of the thighbone, which can lead to additional pain and arthritis. Arthroscopic surgery can correct this condition.

If the kneecap is only partially dislocated, I may recommend nonsurgical treatments, such as exercises and braces. Exercises will help strengthen the muscles in your thigh so that the kneecap stays aligned.

Cycling is often recommended as part of the physical therapy. A stabilizing brace may also be prescribed. The goal is for you to return to your normal activities within 1 to 3 months.

SURGICAL TREATMENT

Surgical planning is very important, since many a times, multiple factors contribute to recurrent patellar instability.

MPFL reconstruction: The ligament that holds the kneecap in position is called as Medial Patellofemoral ligament (MPFL). Using one of the extra tendons from your inner thigh, I will reconstruct this ligament using an arthroscopy assisted minimally invasive procedure.

Trochleoplasty: The groove deepening procedure is a complex surgery and one of my favourites. I will take out some bone fron the central part of the femoral groove and deepen the native grove without damaging the cartilage so tat the knee cap tracks normally.

Derotation DFO: If there is a rotational malalignment, this complex osteotomy will change the anatomy for the better to improve patellar stability

Tibial tubercle transfer: The attachment of the patellar tendonon to the shin bone may be causing a outward pull on the patella and this can be corrected by shifting tibial tubercle medially (inwards).

These surgeries may be required in isolation of combination depending upon the nature and severity of the problem.

I have published my series of patellar stabilization and MPFL reconstructions that shows no failure at short to midterm follow up. (Details in publications)