June 2004

The lowdown on high 'Q' angles

by Dr. Mark Charrette

The quadriceps ('Q') angle is the angle between the quadriceps muscle (primarily the rectus femoris) and the patellar tendon.[1] When assessed correctly, it supplies useful information concerning the alignment of the pelvis, leg, and foot. It also provides useful information regarding the alignment of the knee in the frontal plane. Since large forces are transmitted through the patella during extension, misalignment will cause problems with knee function.

Measurement and ranges

To measure the Q angle, start with the patient's knee and hip in extension, and the quadriceps muscle relaxed. Place the center axis of a long‑arm goniometer over the center of the patella. Next, palpate the proximal tibia and align the lower goniometer arm along the patellar tendon to the tibial tubercle. Take the upper arm of the goniometer and point it directly at the anterior superior iliac spine (ASIS). The small angle measured by the goniometer is the Q angle.

When measured standing, the Q angle should fall between 18 degrees and 22 degrees.[2] Males are usually at the low end of this range, while females (because of their wider pelvis) tend to have higher measurements. One study considers standing Q angles greater than 25 degrees in females and 20 degrees in males to be abnormal.[3]

When measured in the supine position, the values will be lower, and the normal range ends at 15 degrees in males and 20 degrees in females.[4] When it comes to the quadriceps angle, less is generally better than more.

Associated problems

‑‑ Higher measurements. A Q angle measured at the higher end of the normal range indicates a tendency for added biomechanical stress during strenuous or repetitive activities using the knee. When the measurement is above the normal limits, the probability of developing knee joint symptoms increases rapidly. These problems are dependent on a number of factors, including habitual forces on the knee and other alignment abnormalities.

‑‑ Overpronation. Whenever a patient has excessive pronation of the foot, Q angle stresses are magnified. Prolonged time in pronation causes excessive internal rotation of the tibia, impeding its normal external rotation during gait progression in the stance phase. This excessive internal tibial rotation transmits abnormal forces upward in the kinetic chain and produces medial knee stresses, force vector changes of the quadriceps mechanism, and lateral tracking of the patella.[5] The combination of a higher Q angle with excessive pronation causes a more rapid progression from knee dysfunction to patellofemoral arthralgia to degenerative joint disease.

Lowering the angle

‑‑ Orthotic supports. The most effective way to decrease a high Q angle and to lower the biomechanical stresses on the knee joint is to prevent excessive pronation with custom‑made, flexible orthotics.[6] One study found that using soft, corrective orthotics was more effective in reducing knee pain than a traditional exercise program.[7] A more recent study shows that Q angle asymmetries, secondary to excessive pronation affecting knee alignment, can be effectively controlled or corrected utilizing custom‑made, flexible orthotics.[8]

‑‑ Adjustments and exercises. While no adjustment has been reported to reduce the Q angle, a search for pelvic and knee misalignments should be part of care. It is important that good biomechanical function be restored to all joints of both lower extremities.

Stretching of tight muscles and strengthening of weak areas should be included. Muscles commonly found to be tight include: quadriceps, hamstrings, iliotibial band, and gastrocnemius. The vastus medialis obliquus (VMO) is usually weaker than the opposing vastus lateralis muscle. Sometimes it is the coordination of these muscles that has become abnormal. Strengthening may require a special focus on the timing of muscle contractions. Closed chain exercises (such as wall squats) done only to 30 degrees of flexion are currently recommended.[9]

References

1. Magee DJ. "Orthopedic Physical Assessment." Philadelphia: WB Saunders, 1987:296.

2. Loudon JK, Jenkins W, Loudon KL. "The relationship between static posture and ACL injury in female athletes." J Ortho Sports Phys Ther 1996; 24:91‑97.

3. Post WR. "Patellofemoral pain: let the physical exam define treatment." Phys Sports Med 1998; 26.

4. Hvid I, Anderson LB, Schmidt H. "Chondromalacia patellae: the relation to abnormal patellofemoral joint mechanics." Acta Orthop Scand 1981; 52:661‑669.

5. Tiberio D. "The effect of excessive subtalar joint pronation on patellofemoral mechanics: a theoretical model." J Ortho Sports Phys Ther 1987; 9:160‑165.

6. D'Amico JC, Rubin M. "The influence of foot orthotics on the quadriceps angle." J Am Podiatr Med Assoc 1986; 76:337‑340.

7. Eng JJ, Pierrynowski MR. "Evaluation of soft foot orthotics in the treatment of patellofemoral pain syndrome." Phys Ther 1993; 73:62‑70.

8. Kuhn DR, Yochum TR, Cherry AR, Rodgers SS. "Immediate changes in the quadriceps femoris angle after insertion of an orthotic device." J Manip Physiol Ther 2002; 25(7):465‑470.

9. Johnson RM, Poppe TR. "Considering patellofemoral pain: exercise prescription." Strength Condition J 1999; 21:73‑75.

(Mark N. Charrette, DC, is a 1980 summa cum laude graduate of Palmer College of Chiropractic. Over the past 18 years he has lectured extensively on spinal and extremity adjusting throughout the U.S., Europe, the Far East, and Australia. In 1976, he received a Bachelor's degree from Illinois State University [summa cum laude] where he was an NCAA All‑American in 1974.)