08 8232 8899

Surgery for Patellar Instability

Patellar instability refers to the increased likelihood of the patella displacing or dislocating again and again after the first occurrence.

It is not uncommon in young people aged 16-20 who play sports – particularly if there is a sudden twisting action on the knee or an impact with the knee. It can also occur when someone slips and/or falls.

Individual physiological differences in bone shape and structure make some people more prone to patellar instability. Some of these include:

  • Patella alta: where the patella is in a higher position than usual.
  • Increased Q-angle: where there is an increased lateral pull on the patella during knee movement.
  • Trochlear dysplasia: where the groove in which the patella tracks is too shallow.

MPFL injury where the medial patello-femoral ligament that is an important restraint to patella dislocation is torn is present in most patellar instability knees.

Dislocation of the kneecap can be very painful, but milder cases of the patella displacing can be accompanied by only a small amount of pain.

A full physical examination of the affected knee will generally be required, with an x-ray generally required to confirm what type of patellar instability has occurred. In many cases physiotherapy is the only treatment required, with a series of exercises to strengthen the muscles around the knee cap. If physiotherapy does not address the issue, then surgery may be needed.

Procedure

Using arthroscopic (keyhole) techniques, a small camera is inserted into the knee to allow the surgeon to assess any internal damage.

Surgical treatment focuses on the pathology to be addressed and aims to correct one or all of the physiological issues outlined above. More often the instability is due to injury to the medial patella-femoral ligament, which would need reconstruction. This procedure is called MPFL reconstruction with gracilis tendon graft.

Depending on the pathology present, further open surgery may be required – a procedure referred to as ‘tibial tubercle osteotomy’. The tubercle is a protrusion on the tibia (shin) bone where the patellar ligament attaches. In this procedure, the tubercle is relocated on the bone to align the patella properly.

Rehabilitation guidelines for medial patello-femoral ligament reconstruction

The timelines mentioned are approximate and actual progression depends on individual recovery.

Patients can weight bear as tolerated from day one. Please use crutches until good pain control, quadriceps strength, and walking mechanics are achieved.

Apply ice packs three to five times a day for 10 minutes each time for the first two weeks.

A hinged knee brace is to be worn when weight bearing and walking for four weeks.

Range of movement allowed is 0-60 degrees for two weeks, then 0-90 degrees until four weeks after surgery.

Exercises focus on recruiting VMO (vastus medialis obliqus) muscle and strengthening quadriceps, hip abductors, and core.

First two weeks

  • Weight bear and mobilise as tolerated.
  • Start quadriceps sets and ankle pumps early on.
  • Range of movement is 0-60 degrees only.

Two to four weeks

  • Progress with walking and functional exercises.
  • Progress with single leg stance, balance, and proprioception.

Four to eight weeks

  • Start no-resistance stationary bike.
  • Functional exercises – focus on eccentric exercises.
  • Pool exercises.
  • Progress with range of movement and step-ups.
  • Remember all exercises are closed-chain and functional.

12 weeks+

  • Start resistance training.
  • Work or sport-specific training commences.