What is Anterior Knee pain?

Anterior knee pain, or simply pain experienced around the front part of the knee, may arise from any of several conditions.  Acute pain in the front of the knee can be due to twisting or contact injuries that may have caused breaks in the bone or cartilage, dislocations or ligamentous injuries. Furthermore, chronic pain in the front and centre of the knee is also common among active and non-active people. Up to 30% of all visits to sports medicine practitioners are for anterior knee pain.

Pain receptors are present within several knee structures, including the patella, synovium, fat pad, tendon, subchondral bone and quadriceps muscle. Any of these structures, individually or in combination, can cause anterior knee pain.

Pre-disposing factors to anterior knee pain:

• poor patellar alignment
Maltracking, rotation or tilt of the patella
• abnormal alignment of the lower extremities
Poor foot posture (eg flat feet)
Increased rotation of lower limb bones (tibia, fenur)
• increased q angle
affected by width of pelvis, hip rotation and position of tibial tubercle
• functional imbalances
muscle weakness (quadriceps (VMO), gluteals (buttock))
muscle tightness (calf, hamstring, ITB)
• excessive training or overuse
• poor footwear
• gender
more common in females

The two most common conditions of anterior knee pain are patello-femoral syndrome and patellar tendinosis / tendonopathy.

What is Patello-femoral Pain Syndrome (PFPS)

PFPS is caused by incorrect tracking of the kneecap as the knee bends and straightens. Due to this malalignment, the patella rubs against the femur bone causing pain, instead of smoothly gliding in the groove it is intended to. PFPS is extremely common; it usually affects adolescents at the time of increased growth and affects girls more than boys, often limiting sporting activity.

How is it diagnosed?

Symptoms:

• Diffuse pain that gradually worsens with activity
• pain with prolonged sitting (moviegoer's knee)
• pain with descending or ascending stairs
• pain with squatting or kneeling
• feeling of giving way
• a crunching sensation (crepitus)
• pseudolocking
• swelling

Examination findings:

• Pain is produced on any of the above tests
• Signs of malalignment and/or muscle weakness
• Chronic conditions coexisting including i.e. ACL deficiency

What treatment is available?

A detailed physical examination, including functional testing is needed to correctly diagnose and manage PFPS. Current evidence suggests(A):

1. Reassurance and education are the most important components of multimodal therapy.
 
2 Reduce the pain and inflammation initially by resting the knee; regular applications of ice and sometimes NSAIDs (non-steroidal anti inflammatories) may be of use. Some athletes temporarily change to non-weight bearing activity such as swimming.

3. Taping techniques to correct any abnormal patella alignment minimise pain and facilitate quadriceps (thigh) muscle activation.

4. Muscle stretching and strengthening program to improve control of the patella.

5. Correct pre-disposing factors to prevent recurrence.

Conservative treatment is highly successful and is the primary method of treatment with surgery being reserved for those that don’t respond (they are often those with severe malalignment factors or joint degeneration).

Surgical procedures may include; lateral retinacular release, distal realignment, patellar shaving, and patellectomy (not routinely done). Results of these surgeries are controversial and rely on strict selection criteria from surgeons.

What is Patellar Tendinosis / Tendinopathy?

The patellar tendon is a strong tendon joining the patella to the shin bone (tibia). It assists the quadricep muscles to straighten the knee actively when jumping and stabilizes the knee in landing positions. A patellar tendinosis is described as degenerative change within the tendon and failed healing in response to load. This is usually caused by overuse of the patella tendon causing pain, from an increase in volume, intensity or frequency of loading. Interestingly there is no inflammation present and the cause of the pain is unknown.

How is it diagnosed?

Symptoms:

• localized pain over the patella tendon (raning from a dull ache to sharp)
• jumping and landing increases the pain
• tenderness around the lower part of the patella
• pain with descending stairs
• fast squats aggravate the pain

What treatment is available?

A detailed physical examination, including functional testing is needed to correctly diagnose and manage a patella tendinopathy. Current evidence suggests:

1.    Rest initially by avoiding aggravating activities
2.    Ice initially to reduce pain
3.    Unload the tendon
a.    Aim to improve the energy absorbing capacity of the whole limb
b.    Modify training
c.    Soft tissue massage to release tight structures
d.    Address biomechanical problems at the hip, knee and foot
e.    Use of tape and braces (Cho pat)
4.    Stretching program to improve flexibility of the hamstrings and quadriceps
5.    Strengthening program to increase the quadriceps strength and control over the knee.

Diagnosing these two conditions can often be difficult as they often have similar symptoms and can even present together.

How is it diagnosed?

The complex anatomy of the knee joint that allows it to bend while supporting heavy loads is extremely sensitive to small problems in alignment, training and overuse. It is therefore beneficial to prevent knee pain by:

• Maintaining good general fitness
• Stretch regularly
• Increase training gradually - avoid sudden changes
• Wear supportive running shoes with good shock absorption

What other conditions can cause anterior knee pain?

Quadriceps rupture
Patellar instability
Fractures of the patella
Sinding-Larsens-Johansson’s disease
Osgood-Schlatter’s disease