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Patellar Instability

Several types of operations are used for patients who experience recurrent patella dislocation or persistent patella instability symptoms despite physiotherapy.The type of operation performed depends on the individual factors affecting each patient, sometimes a combination of operations is required.The most commonly used stabilisation procedure is a medial patello-femoral ligament (MPFL) reconstruction

MPFL Reconstruction

MPFL Reconstruction surgery involves a general or spinal anaesthetic as a day case or overnight stay.

The aim of the operation is to rebuild the torn Medial patello-femoral ligament using the hamstring tendon along the same principles as an ACL reconstruction.
The procedure is usually performed using arthroscopic assistance and is aimed at replacing the deficient ACL with a graft ligament to stabilise the knee.The semitendinosus hamstring tendon is normally used as the graft to form the new ligament. This graft is taken through a small incision (4cm approximately) over the inner aspect of the shin just below the new.

The tendon is passed through drill hole in the femur and patella so that it lies in the same position as the medial patello-femoral ligament. This requires further small incisions over the femur and inner aspect of the patella. It is held in place with a screw or similar device in the femur and patella.

 

 

Success

This procedure recreates an ‘anatomic’ MPFL and is effective in preventing further dislocation in more than 90% of patients.

Risks

MPFL reconstruction is a reliable operation, however, there is a small risk of problems or complications with any surgery.
These risks include:
Infection can occur with any operation. Special precautions are taken during surgery to diminish this risk, however, the risk still exists but there is <1% chance of developing a serious infection.
Injury to blood vessels or nerves. Major injuries to these structures are extremely rare, although it is not uncommon to develop some reduced sensation around the shin wound, this rarely causes a problem
Deep vein thrombosis (blood clots) can also occur as with all operations (<0.2%).
Stiffness of the knee joint after MPFL surgery can occur. It is normal for patients to take six to twelve weeks to regain a full range of movement of the knee. Occasionally it can take longer but it is rare for patients not regain full range of movement t in the long term.
All these risks are uncommon and in total, the chance of being worse off in the long term is about or less than 1%.
Re-current dislocation can still occur but the risk of this is probably less than 10%

Rehabilitation

Surgery is followed by a prolonged course of physiotherapy. This requires a commitment to undertake this rehabilitation in order to achieve the best possible result.
Return to work

The timing of your return to work depends on the type of work and your access, however, the following is a guide:
Driving: when you can walk without crutches or a limp and be in control of your vehicle (about 4 weeks).
Desk work: as soon as pain allows and you can travel easily to and from work (2 weeks)
Light duties: if the job allows partial use of crutches or limited walking (2-5 weeks). If the job involves standing for prolonged walking, bending, lifting, stairs but no squatting (7-8 weeks)
Heavy duties: full squatting, heavy lifting, digging, in and out of heavy machinery, ladder work etc (3-4 months)

Extensor Mechanism Realignment

This type of surgery usually involves altering the position of the tibial tuberosity to which the patella tendon is attached. This alters the angle of ‘pull’ of the quadriceps muscles on the patella for patients in whom this pull is likely to cause dislocation of the patella.

The operation involves an 8cm incision in addition to the arthroscopic incisions over the lateral aspect of the upper shin just below the knee. The tibial tubersoity is cut, moved medially and held in its new position with screws.

Afterwards there are 1 or 2 nights in hospital, protection of the knee for up to six weeks and a rehabilitation programme for around 3 months.

Risks

No operation is without risk. Complications that can occur include: Infection of the bone or joint (<1%)
Blood clots which can be minor (0.25%) or serious, even fatal (1/5000)
Anaesthetic risk is extremely low.
Others: rarely nerve damage, vessel damage, poor skin healing, tethering, urinary tract infection, drug reactions and other possible unexpected outcomes can occur.
Recurrent dislocation can occur in around 10% of patients.

Post-Operative Rehabilitation following Patella Realignment Surgery

In hospital – one or two nights.
Home in a splint and on crutches. Splint off only for bath or shower. Simple quadriceps tensioning exercises. Touch weightbearing only. Keep the wound covered and clean and dry (leave the dressing alone).
2 weeks: post-op appointment and dressing removed.
2-4 weeks: Progress weightbearing on crutches and gentle range of movement exercises and quadriceps contraction exercises. Increase weightbearing as tolerated. Brace off for exercises, showering and at rest.
4-6 weeks: expect 0-50º movement, comfortable protected weightbearing. Use crutches or brace as tolerated. Progress quadriceps strength. Become independently mobile.
6 weeks: 0-90º of flexion. Comfortable with short walking. Straight leg control. To have an x-ray if had bony surgery. Attend regular physiotherapy. Begin more advanced rehabilitation including step-ups, bike, mini-trampoline, and swimming.
8 weeks: Progress strength exercises with light resistance; include step machine, single knee bends, mini-trampoline (jumps).
10 weeks: progress agility on step-ups, short runs, stop starts, increased strength.
12 weeks: progress sports specific drills and activities.