Dance Anatomy & Kinesiology

258 Dance Anatomy and Kinesiology

is particularly important in the initial stages of knee

flexion, before the patella becomes well seated and

more stable at about 20° of flexion.

Patellofemoral Alignment and the Q Angle

The shape, height, mobility, and facing of the patella

in the femoral groove, as well as its angular relation-

ship to the tibia, are important for determining

stability and tracking of the patella. This angular

relationship is termed the Q angle. The Q angle

or quadriceps angle is a static measurement of the

angle that the patellar tendon makes relative to the

shaft of the femur as seen in figure 5.16. Since the

patella is relatively free to move upon the femur

when the knee is extended, when the quadriceps

femoris muscle contracts it will try to establish a

straight line between its proximal attachment onto

the femur and pelvis and its distal attachment onto

the tibial tuberosity. Thus, the Q angle provides an

indication of the lateral force (vector) applied to the

patella, which tends to make the patella track later-

ally in order to establish a straight-line relationship

between the proximal and distal attachments of the

quadriceps femoris muscle group. Females gener-

ally have larger Q angles than men, with a normal

range considered to be 8° to 15° for males and 10°

to 19° for females (Diduch, Scuderi, and Scott,

1997; Hamill and Knutzen, 1995; Palmer and Epler,

1990) when the knee is in extension and the quad-

riceps is relaxed. Although controversial, Q angles

greater than 15° (Insall, Bullough, and Burstein,

1979; Quirk, 1987), 17° (Hamill and Knutzen, 1995),

or 20° (Caillet, 1996; Smith, Weiss, and Lehmkuhl,

1996) are considered abnormal and a risk factor for

patellofemoral problems.

Patellofemoral Mechanics

Underlying positioning, movement, and the forces

associated with patellofemoral function are two

FIGURE 5.14 The patellofemoral joint (right knee). (A) Anterior view of the patellofemoral joint and associated key

muscles and connective tissues, (B) anterior view of location of patella relative to the femur, (C) posterior view of the

patella showing facets, (D) inferior view of the location of the patella relative to the femur.