LIVRE JDG 2012

E.A. Arendt

368

Anterior Knee Pain

As with most pain issues, anterior knee pain

often has a root cause that is unknown or

unclear, with multiple confounding variables.

An analysis of alignment, strength deficit, and

potential inciting overuse factors must be

elicited by a careful history and physical exam

by the treating clinician.

Guiding principles

1. Identify and restore muscle imbalance

esp. proximal hip and pelvic regions.

2. Maximize “modifiable” alignment issues.

Most specifically, this refers to foot position

and pelvic position. A neutral foot position is

favored over a pronated foot position; a neutral

pelvis is favored over positions of excessive

pelvic tilt or obliquity. In most patients these

are not fixed deformities, but are capable of

being repositioned with foot support and/or

dynamic muscle strengthening.

There is increasing evidence in the literature

linking weak hip musculature and poor pelvic

control with anterior knee pain. Rotational

control of the limb underneath the pelvis is

critical; this is largely achieved through the

roles of gluteus medius and maximus

musculature as closed kinetic chain (CKC)

stabilizers. Strength of these muscle groups is

of paramount importance, as a lack of rotational

control of the limb can result in a valgus

collapse pattern that places the knee at risk for

acute and overuse knee injuries (fig. 1a).

3. Examine patterns of overuse.

This can be a

repetitive exercise activity such as running,

or repetitive work activities that involve

lifting, squatting, and/or stair climbing. One

must have adequate muscular strength and

endurance to perform repetitive activities. If

one part of the kinetic chain is weak or

injured, the body often finds ways to

accomplish an activity by “working around”

the injured body part. This often initiates

faulty body mechanics that lead to a painful

state that centers on the patella and its

associated soft tissue structures. One must

reduce activities to remainwithin an envelope

of pain-free function. Once one is within an

envelope of pain free activities, the patient

can begin to expand their envelope

concomitant with improvement in strength,

coordination, balance, and overall dynamic

control of the limb.

Abnormal motion patterns when

performing a Partial Squat

Observation of a patient doing a partial squat

can uncover many movement patterns that can

relate to PF pain and dysfunction.

1. Anterior Knee Excursion

(fig. 1b): This

refers to the excessive anterior translation of

the knee with squatting, thus projecting the

torso (center of mass) forward over ones’

toes. The patella is thus placed in a position

to help keep the torso upright, increasing

joint reaction force. It is, in part, the end

result of the lack of integrating posterior

muscles in this body movement pattern.

Excessive anterior knee excursion should be

avoided for multiple reasons including

excessive PF joint loading, inadequate hip

joint utilization/muscular recruitment, and

excessive ankle dorsiflexion demands. This

is a very common “habit” seen in young

teenage girls.

With squat retraining, it is critical to employ a

balanced hip and knee strategy in the sagittal

plane. Patients often need to be instructed to

“sit back” into hip flexion, with associated

forward trunk lean, to allow a more centered

distribution of the center of mass in the anterior/

posterior direction and thus a more balanced

load distribution between the joints of the lower

extremity (fig. 2 a & b). Cueing the patient to

“sit down on a chair” or “lead with their

buttocks” can be helpful to begin proper

execution of this exercise.

2. Functional knee valgus

(fig. 1a): The need

to control the alignment of the limb in the

frontal and transverse planes is of primary

importance in the goal of optimal lower