Anterior Knee Pain
Other popular names
- Kneecap instability
- Patella Maltracking
- Lateral Release (Arthroscopic)
- Who does it affect?
Anyone. In some patients this tendency is greater than others due to their own individual body shape and bony anatomy. In others it may be due to injury.
Why does it happen?
Anterior knee pain (pain at the front of the knee) is common and can be caused by a variety of conditions.
The patello-femoral joint refers to the part of the knee joint at the front of the knee between the patella (knee cap) and femur (thigh bone). The patella is connected to the quadriceps tendon at the top of the patella. This tendon attaches the quadriceps muscles which are attached to the femur and pelvis above. The patellar tendon goes from the bottom of the patella to the front of the tibia and attaches at a point called the ‘tibial tubercle’. When the quadriceps muscle contracts , it pulls the patella which in turns pulls on the tibial tubercle. This causes the knee to extend (straighten). As the knee moves, the patella glides across the front of the knee joint in a shallow groove (trochlear groove).
There are several types of abnormalities that may occur. The patella may:
- dislocate (slip out of place)
- sublux (partially slip out of place)
- fracture (break)
- develop degenerate arthritis (wear)
- develop a tracking problem. A tracking problem refers to when the patella stays in place in front of the knee but no longer remains centred in the front part of the femur known as the trochlear groove.
If any imbalance occurs, the patella begins to move laterally (towards the outside) within the trochlear groove. As it flexes, the tension increases on the tight lateral structures. In turn, this causes pain with bent knee activities. This results in abnormally increased contact between the femur and the patellar articular surface which eventually results in arthritis. If the imbalance is overwhelming, then the patella may actually slip out of place, referred to as dislocation.
The overall risk of having further episodes of patella instability is in the order of 50%, although the individual risk varies enormously depending on the pre-disposing factors present.
Pain and instability across the joint.
Most patello-femoral problems are diagnosed on the basis of the knowledge of symptoms and the findings on clinical examination.
X-rays and MRI scans can help to confirm the diagnosis and the severity of the condition.
Fortunately, most patients with anterior knee pain from whatever cause, benefit from physiotherapy that is tailored to their precise problem.
Surgery can be offered for patients who do not respond sufficiently to physiotherapy and they can often benefit from arthroscopic intervention.
For patients with a tight lateral retinaculum an arthroscopic lateral release, where the tight tissues are divided to reduce pressure on the patella, can be of great benefit.
Patients who develop severe arthritis affecting the patello-femoral compartment of the knee only might eventually require a patello-femoral joint replacement.
Surgery is most commonly in the form of a medial patello-femoral ligament reconstruction but can also involve realignment of the patello-femoral joint with an osteotomy of tibial tuberosity to alter the angle of pull of the quadriceps tendon and sometimes more complex operations.
This surgery will be performed under general anaesthetic and could take anything from 30 – 90 minutes.
You are likely to stay in hospital 1-3 days. All patients will need someone to take them home.
The anaesthetic will wear off after approximately 6 hours. Simple analgesia (pain killers) usually controls the pain and should be started before the anaesthetic has worn off.
Patients need to use crutches for the first 2 weeks following surgery although they can fully weight-bear - the crutches are mainly to prevent falls until good muscle control has been regained to the leg.
The large bandage around the knee is normally removed 24-48 hours after surgery and a tubigrip to supply gentle compression to reduce post-operative swelling.
The non-stick sterile dressings on the wounds are replaced with clean waterproof dressings .
Return to normal routine
Bathing and showering
The wounds should be kept clean and dry until the wound has sealed. Showering is fine and the waterproof dressings can be changed afterwards. Bathing is best avoided until the wounds are sealed, typically 10 days after surgery.
In summary, whilst the wounds are wet - keep them dry and when the wounds are dry, you can get them wet!
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 (at least half an hour per day for 6 months). It is vitally important to stay within the post-operative activity restrictions an physiotherapy guidelines to avoid damaging stretching your reconstructed ligament.
Return to work
The timing of your return to work depends on the type of work and your access, however, the following is a general guide:
- 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)
When you can walk without crutches or a limp and be in control of your vehicle (about 4-6 weeks).
This procedure is safe and effective in preventing further pain in more than 90% of patients. It 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 / pulmonary embolus (DVT / PE) (blood clots) can also occur as with all operations (<0.2%).
- Stiffness of the knee joint after 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 in the long term.
- Re-current dislocation can still occur but the risk of this is probably less than 10%
All these risks are uncommon and in total, the chance of being worse off in the long term is about or less than 1%.