The physical therapist's approach to patellofemoral disorders

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Anatomy

The patellofemoral joint is largely a soft-tissue joint. In the first 20°, the patella is under the influence of the surrounding soft-tissue structures so that it is particularly vulnerable and susceptible to problems. After 20° of knee flexion, the bony architecture is increasingly responsible for controlling the position of the patella. The soft tissues on the lateral side, forming the lateral retinaculum, are thick and well organized. Most of the lateral retinaculum, particularly the deep

Functions of the patella

The major functions of the patella are to increase the extensor moment of the quadriceps muscle and to minimize the concentration of stress by transmitting forces evenly to the underlying bone [2], [3], [10], [11]. The patella is like a balance beam that adjusts the length, direction, and force of each of its arms—the quadriceps tendon and the patella tendon—at different degrees of flexion. When the knee is extending, the patellofemoral contact area moves from proximal to distal on the patella

Biomechanical considerations

The patellofemoral joint reaction force (PFJRF) is equal and opposite to the resultant of the quadriceps tendon tension and the patellar tendon tension. This force is a compressive force increasing with flexion as the angle between the patellar tendon and the quadriceps becomes more acute. It changes from 0.5 × body weight, during level walking, to 3 to 4 × body weight, during stair ascent and descent, 7 to 8 × body weight when squatting, and 20 × body weight when jumping [2], [3]. The increase

Factors predisposing to patellofemoral pain

It also is suggested that individuals with patellofemoral pain are outside their envelope of function and no longer in homeostasis [12]. They demonstrate a failure of the intricate balance of the soft-tissue structures around the joint, such that there may be an alteration of the pressure distribution from the patella to the femur. Many causes of patellofemoral pain are cited in the literature, but the mechanism of pain production is not understood fully.

Patellofemoral pain is most likely

Examination

The clinician needs to obtain a detailed history from the patient to establish a diagnosis. This is later confirmed or modified by the physical findings. The clinician must elicit from the history the area, behavior, and onset of the pain; the symptom-provoking activities; and the presence of other symptoms, such as clicking, giving way, or swelling. This information provides an indication of the structures involved and the likely diagnosis.

Treatment

Most patellofemoral conditions may be successfully managed with physical therapy. The aims of the treatment are twofold: first, to unload abnormally stressed soft tissue around the patellofemoral joint by optimizing the patellar position and second, to improve the lower limb mechanics, which, if executed well, significantly decreases the patient's symptoms. A summary of the treatment approach is outlined in Table 2.

Stretching the tight lateral structures and changing the activation pattern of

Patellar taping

Patellar taping is unique to each patient, as the components corrected, the order of correction, and the tension of the tape are tailored for each individual based on the assessment of the patellar position. The worst component is always corrected first, and the effect of each piece of tape on the patient's symptoms should be evaluated by reassessing the painful activity. It may be necessary to correct more than one component. After each piece of tape is applied, the symptom-producing activity

Unloading

The principle of unloading is based on the premise that inflamed soft tissue does not respond well to stretch. For example, if a patient presents with a sprained medial collateral ligament, applying a valgus stress to the knee aggravates the condition, whereas a varus stress decreases the symptoms. The same principle applies for patients with an inflamed fat pad, an irritated iliotibial band, or a pes anserinus bursitis. The inflamed tissue needs to be shortened or unloaded. To unload an

Muscle training

It could be argued that individuals with poor mechanics need the VMO to fire earlier than the VL to overcome the abnormal tracking forces. Thus, the ability to selectively fire the VMO probably is a learned skill rather than an innate ability, much like training the abductor hallucis or individually isolating one frontalis to elevate one eyebrow and not the other. Training should, therefore, enhance this ability.

The current debate regarding rehabilitating the patellofemoral joint is about the

Pelvic stability

A stable pelvis minimizes unnecessary stress on the knee. Training of the gluteus medius (posterior fibers) to decrease hip internal rotation and the consequent valgus vector force that occurs at the knee is necessary to improve pelvic stability. The posterior gluteus medius may be trained in weight-bearing, with the patient standing side-on to a wall. The leg closest to the wall is flexed at the knee so the foot is off the ground. The hips are in line with each other. The patient should have

Evidence for nonoperative management

A recent randomized, double-blind, placebo-controlled trial of the program described in this article, consisting of six treatment sessions, once weekly in 71 PFPS patients, shows that the physical therapy group demonstrates significantly better response to treatment and greater improvements in pain and functional activities than the placebo group [59]. Thus, physical therapy not only significantly improves pain and function [59], [60] but also alters EMG onset of VMO relative to VL compared

Summary

Management of patellofemoral pain is no longer a conundrum if the therapist can determine the underlying causative factors and address those factors in treatment. It is imperative that the patient's symptoms are significantly reduced. This often is achieved by taping the patella, which not only decreases the pain but also promotes an earlier activation of the VMO and increases quadriceps torque. Management needs to include specific VMO training, gluteal-control work, stretching tight lateral

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