Q-Angle and Patellofemoral Pain Syndrome

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Watch Our Video on the Q-Angle by Tim Maggs, DC.

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This paper targets one specific knee condition (patellofemoral pain syndrome), offers a possible indicator for predicting patients at risk (Q-angle measurement) and suggests adjunctive treatment options (rehab exercises and flexible custom orthotics).

Knee pain, in its most generalized definition, is experienced by millions of people of all ages and in every walk of life. Its effect on lifestyle can range from slightly uncomfortable on a periodic basis to total debilitation. Treatment options reflect the level of severity: from a symptom-masking over-the-counter pain reliever for the mildest cases to Chiropractic treatment and rehabilitative therapy, all the way to reconstructive surgery for the most damaging situations. As in many musculoskeletal conditions, early intervention and treatment can often prevent more serious problems later on.

Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (“PFPS”) is a common problem which occurs with mild malalignment of the extensor mechanism of the knee or as a result of repetitive microtrauma from overuse.1 Malalignment often occurs when the patient has a weak vastus medialis.2 Patients most often present with retropatellar or peripatellar knee pain, which becomes especially noticeable when they climb or descend stairs.1

There are many effects for these cases. Some are an altered Q-angle, pes planus or cavus, tight hamstrings and a tight iliotibial band. Malaignment can also cause subluxation and patellar dislocation. For children, patellofemoral pain can be caused by trauma.2

The Q-Angle Connection

The angle formed by the force of the quadriceps femoris muscle on the base of the patella and the line of pull of the patellar ligament on the apex of the patella is called the quadriceps femoris angle, or “Q-angle”.3,4 An abnormally high Q-angle has been implicated as a source of several knee disorders,4,5 including PFPS.2 Additionally, this is one of several factors associated with an increased incidence of chondromalacia patellae and patellar tracking dysfunction.6,7

Q-Angle Measurement

In clinical practice, the Q-angle is measured by drawing an imaginary line from the anterosuperior iliac spine (ASIS) to the center of the patella, and from the center of the patella to the tibial tuberosity (Fig. 1). Most investigators measure the Q-angle in the supine position, but some measure it in the standing position, and others do not specify. Standing postural variations, such as increased foot pronation and genu valgum, are thought to have an influence on the Q-angle and patellofemoral function.8,9,10 Because weightbearing and locomotion are the knees’ most vital functions, the relationship of the supine and standing Q-angle measurement is an important consideration.11 Standardizing the position of the foot and procedures for measuring the Q-angle is recommended.5,10

A variety of “normal” Q-angle values, ranging from 8˚–17˚, has been offered in the literature. Generally, women have higher Q-angles than men,4,12 which most authorities attribute to their wider pelvic base, resulting in a more lateral proximal reference point. Optimum measurement for males is 8­–12˚; for females, 12–15˚.6,7 Q-angles higher than 15˚ for men and 20˚ for women are considered clinically abnormal (Fig. 2).12,13

Biomechanics

Biomechanical disturbances of the lower extremity can be the cause of many cases of chronic knee pain.14,15 Excessive rotation of the bones, both internal and external, as well as muscular imbalance can contribute to or aggravate a range of conditions, particularly those involving the patella. In discussing clinical examination techniques, it was noted that subtalar joint pronation may accompany certain disorders, such as PFPS.16 An increased Q-angle is one indication of foot pronation.

In normal gait a natural inward rotation of the foot occurs at heel strike. The tibia immediately rotates internally, with the femur moving slightly as well. This normal rotation of the foot should not exceed 8˚ while walking or 12˚ while running to maintain optimal function.17

Excessive pronation is transmitted to the tibia and femur, where inward rotation jeopardizes the patello-femoral complex. Normal interaction with the patellar tendon and quadriceps keeps the patella directly superior in the femoral groove.18 A patellar subluxation, or disturbance of its normal juxtaposition to surrounding structures, frequently results.13 Then, the apex of the patella moves medially and the whole structure moves laterally. In clinical practice observations of these knee conditions may be attributed to excessive pronation or supination of the foot.

Alterations in normal biomechanics of the lower Kinetic Chain can predispose patients to premature degenerative disease in the lower lumbar spine, hip, knee, foot or ankle. Consequently, extensive degenerative disease of the medial and retropatellar compartments of the knee may result from long-standing foot pronation and chronic dysfunction of the lower limb.19

Exercise Application

Patients presenting with PFPS can benefit from strengthening exercises. According to Kannus and Niittymaki, quadriceps rehabilitation is worth trying for every patient (70% experienced complete recovery), regardless of age, sex, body composition, athletic level, duration of symptoms, or biomechanical malalignments in the lower extremities.20 Developing knee muscles helps stabilize the joint and lower the incidence of serious knee injury.21 Exercise further protects the knee’s biomechanical integrity by aiding ligament function. The ligaments are the secondary stabilizer of the joint.22

The THERA-CISER® therapeutic exercise system enables the patient to perform a range of movements to build strength in muscle groups interacting with the knee. The system is easy to use at home, and affords pain-free movement which benefits a number of chronic knee conditions. The exercise program begins without direct involvement of the knee joint itself. Linear hip movement should be prescribed initially (Fig. 3). Those muscles which interact with knee can gain strength, which begins to build stability in the knee.

The second phase of exercise works the knee in its four basic motions: flexion, extension, and internal and external rotation (Fig. 4). Activities should be undertaken only when the patient is free of pain. Under no circumstance should use of the THERA-CISER cause pain in the knee or other involved area.

Orthotic Support

Currently, there is ongoing research to evaluate the relationship of pronation on the Q-angle and the corrective effects of medial arch support and custom-made flexible orthotics.19 Functional orthotics from Foot Levelers (Fig. 5) can correct pedal imbalances which can cause excessive pronation or supination (Figs. 6, 7), and they can play a major role in preventing many overuse injuries. A case study at a sports Chiropractic clinic of patients with an average Q-angle of 22˚ documents the value of orthotics in controlling Q-angle.13 Forty individuals were fitted with functional orthotics from Foot Levelers. The orthotics alone brought the average Q-angle below 20˚ and to the limits of normal Q-angle range.

In-shoe orthotics have been called “the only method of controlling overpronation at the subtalar joint.”23 Blake and Denton performed a retrospective study of 180 patients (primarily runners) receiving functional foot orthoses.24 The diagnoses included foot/ankle, knee, leg, and hip conditions. The success rate (a response of “definitely helped”) was 70%. D’Amico and Rubin 9 found a highly significant reduction of the Q-angle when orthotics was used. The mean Q-angle was reduced from 17.6–11.6˚.

Yochum demonstrated an example of the benefits of corrective orthotics in reducing pelvic unleveling.25 The pre-orthotics radiograph (Fig. 8, left image) shows a 15.5 mm leg length insufficiency (LLI) on the right. This deficiency was reduced to 4 mm on the follow-up radiograph (Fig. 8, right image) taken with Foot Levelers’ InMotion® orthotic. Not only has the pelvic deficiency been markedly reduced, but the right compensatory listing of the lower lumbar spine has also diminished.

Both cases of excessive pronation and supination will need an effective shock absorption material built into the orthotic to help dissipate shock forces. It has been found that MPAX™ material found in the XP3™ functional orthotic can dissipate more than 90% of the energy of deformation, yet fully return to shape on removal of the force; well within the interval between steps.

Conclusion

An abnormally high Q-angle has been implicated as a source of several knee disorders, including patellofemoral pain syndrome (“PFPS”). A Q-angle higher than the normal average is one indication that a patient may have some type of biomechanical disorder in the lower extremities, with foot pronation a likely candidate. Rehabilitative exercise with THERA-CISER helps to build strength in affected muscle groups. Functional orthotics from Foot Levelers have been shown to reduce the severity of Q-angle, restoring it to more normal levels. Foot Levelers orthotics can also play an important role in preventing many overuse injuries.

References

  1. Davidson K. Patellofemoral pain syndrome. Am Fam Physician 1993; 48(7):1254-1262.
  2. Galea AM, Albers JM. Patellofemoral pain: targeting the cause. Phys and Sportsmed 1994; 22(4).
  3. Ficat PR, Hungerford BF. Disorders of the Patellofemoral Joint. Baltimore: Williams & Wilkins, 1983.
  4. Horton MG, Hall TL. Quadriceps femoris muscle angle: normal values and relationships with gender and selected skeletal measures. Phys Ther 1989; 69(11):897-901.
  5. Guerra JP, Arnold MJ, Gajdosik RL. Q-angle: effects of isometric quadriceps contraction and body position. J Orthop Sports Phys Ther 1994; 19(4):200-204.
  6. Aglietti P, Insall JN, Cerulli G. Patellar pain and incongruence: measurements of incongruence. Clin Orthop 1983; 176:217.
  7. Brattstrom H. Shape of the intracondylar groove normally and in recurrent dislocation of patella. Acta Orthop Scand (Suppl) 1964; 68:1.
  8. Buchbinder MR, Napora NJ, Biggs EW. The relationship of abnormal pronation to chondromalacia of the patella in distance runners. J Am Pod Med Assoc 1979; 69:159.
  9. D’Amico JC, Rubin M. The influence of foot orthotics on the quadriceps angle. J Am Pod Med Assn 1986; 76:337-340.
  10. Olerud C, Berg P. The variation of the Q-angle with different positions of the foot. Clin Orthop 1984; 191:162-165.
  11. Woodland LH, Francis RS. Parameters and comparisons of the quadriceps angle of college-aged men and women in the supine and standing positions. Am J Sprts Med 1992; 20(2):208-211.
  12. Hvid I, Anderson LB, Schmidt H. Chondromalacia patellae: the relation to abnormal patellofemoral joint mechanics. Acta Orthop Scand 1981; 52:661.
  13. Christensen KD. Clinical Chiropractic Biomechanics. Dubuque, IA: Foot Levelers Educational Division, 1984
  14. Shambaugh JP, Klein A, Herbert JH. Structural measures as predictors of injury to basketball players. Med Sci Sports Exerc 1991; 23(5):522-527.
  15. Messier SP, Davis SE, Curl WW, Lowery RB, Pack RJ. Etiologic factors associated with patellofemoral pain in runners. Med Sci Sports Exerc 1991; 23(9):1008-1015.
  16. Powers CM, Maffucci R, Hampton S. Rearfoot posture in subjects with patellofemoral pain. J Orthop Sports Phys Ther 1995; 22(4):155-160.
  17. Cavanagh PR. The Shoe-Ground Interface in Running. Symposium on the Foot and Leg in Running Sports.
  18. Kulund DN. The Injured Athlete. Philadelphia: JB Lippincott, 1982.
  19. Yochum TR, Barry MS. What is the Q-angle? Success Express 1997; 17(5):15-17.
  20. Kannus P, Niittymaki S. Which factors predict outcome in the nonoperative treatment of patellofemoral pain syndrome? A prospective follow-up study. Med Sci Sports Exerc 1994; 26(3):289-296.
  21. Roy S, Irvin R. Sports Medicine Prevention, Evaluation, Management and Rehabilitation. Englewood Cliffs: Prentice-Hall, 1983.
  22. Christensen, KD. Clinical Chiropractic Orthopedics. Dubuque: Foot Levelers, Inc., 1984.
  23. Baycroft CM, Culp V. Running shoes: design facts and functional fantasies. Chiro Sports Med 1993; 7(1):6-8.
  24. Blake RL, Denton JA. Functional foot orthoses for athletic injuries. J Am Pod Med Assn 1985; 75:359.
  25. Yochum TR. The short leg (revised version). In Practical Research Studies (Vol. 4 #5). Roanoke: Foot Levelers, Inc., 1994.

 

Fig. 1. Anatomical landmarks for establishing the quadriceps femoris angle (Q-angle)

Fig. 2. Female and male Q-angles

Fig. 3. Hip abduction rehab exercise with THERA-CISER

Fig. 4. Knee exercise: internal rotation

Fig. 5. Flexible custom orthotics

Fig. 6. Pronation and orthotic correction

Fig. 7. Supination and orthotic correction

Fig. 8. Pelvic unleveling (X-rays)