Monday, April 12, 2010

Patellofemoral joint mobilization in distraction: Review of a Maitland technique on the context patellar tendon adhesion producing anterior knee pain


(Patellar distraction technique)

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It is now universally accepted that patellofemoral malalignment is the main cause of anterior knee pain. The most difficult question to researchers is what is the mechanism whereby patellofemoral malalignment produces pain? Currently, there are two theories one is the neural theory and the other is the mechanical theory. Both theories are not exclusive, but complementary (1).

Development of Patella Baja (Infera) after knee trauma leading to altered knee mechanics & anterior knee pain:

Patella Baja (Infera): Patella Baja refers to low lying patella in frontal plane as compared to normal. This condition develops following repetitive stress or knee traumas due to patellar tendon adhesion following the said two conditions. Patellar tendon adhesion leads to a decrease in the distance between inferior patellar pole to the tibial tuberosity, effectively creating patella infera.

Effect on biomechanics:

Patellar changes:
1. medial and distal translation of the patella,
2. Increased patellar flexion (Inferior pole in-dip).
3. Patellar articular contact location shifted distally but the overall contact area did not change significantly.

Tibial changes: For the tibia, adhesion results in
1. Significant medial, proximal, and anterior translation, and internal rotation.
2. Posterior shift of the tibial contact location.

Quadriceps changes: For the extensor mechanism adhesion results in
1. Decreased the knee extension force created by the quadriceps muscle on the tibia, indicating a decrease in the effective moment arm of the extensor mechanism.
2. Furthermore, as a result of patellar tendon adhesion, the angle formed by the quadriceps and patellar tendons decreased, suggesting an increase in patellofemoral joint reaction force with adhesion.

The increased patellofemoral joint reaction force and the altered contact location may be related to anterior knee pain. Therefore patients should be observed for subtle patella infera, which may indicate patellar tendon adhesion (2).

Maitland PF distraction in treating anterior knee pain with patella baja: (See the figure above)

Not the exact applicative technique is discussed here. Those who are well versed with manual therapy can pick up beneficial tips from the following described technique.

PF distraction:
1. Distraction in PF joint indicates that the patella is lifted away from the femur so that there is no contact between them.

2. This is a very gentle procedure.

3. With PF distraction, 4 other patellar movements can be combined i.e. either longitudinally or to both sides.

A. Patient cues: Supine Ly with the knee extended.

B. Therapist cues:

Stance & position: Therapist positions at the level of the knee facing the knee.

With Both hands:
Both thumbs are placed in the space between the patella and femur medially (or laterally). Then index fingers are placed in the space on the opposite side. Gently squeeze the fingers and thumbs together to reach under the patella & at the same time extend and radially deviate both wrists so that fingers and thumbs lift against the under surface of the patella.

The mobilization act:
1. The technique is a very gentle slow oscillatory movement involving raising and lowering the patella.
2. The patella should not be lowered to the extent where it comes into full contact with the femur.
3. While performing the technique by repeated oscillations, care should be taken to avoid discomfort under the patella.

This technique can be progressed by moving patella in medial, lateral, cephalad or caudad direction. Also as a modification diagonal movements can also be produced.

References:

1. Sanchis-Alfonso V et al; Am J Knee Surg. 1999 Winter;12(1):29-40.
2. Ahmad CS et al; Am J Sports Med. 1998 Sep-Oct;26(5):715-24.

* From Satyajit Mohanty’s clinical peripheral joint manual therapy classes.



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