The Physician and Sportsmedicine
Menubar Home Journal Personal Health Resource Center CME Advertiser Services About Us

Patellofemoral Pain: Let the Physical Exam Define Treatment

William R. Post, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 1 - JANUARY 2021


In Brief: The complex causes of patellofemoral disorders are most effectively identified through a systematic evaluation of a patient's lower-extremity alignment, patellar mobility, muscle flexibility, strength, and coordination as well as an assessment of soft-tissue and articular pain. By combining information from such an exam with a careful history and appropriate radiographic studies, the physician can make a specific diagnosis. This sets the stage for an optimal rehabilitation prescription, which usually will involve some combination of muscle flexibility and strength training, taping, orthoses, analgesics, and therapy with heat and ice.

Primary care and specialist physicians often treat patients who have patellofemoral disorders. These conditions generally respond to nonoperative treatment, but the chance of a satisfactory outcome is best if the treatment is planned in accord with a careful history and a systematic physical exam. The exam should include assessment of alignment, soft-tissue flexibility, muscle strength and coordination, and the location of pain sites. Such an approach will permit the physician to prescribe an exam-directed rehabilitation program that can increase the efficiency and success of nonoperative treatment.

Clues From the History

The first goal in taking a history is to discern whether a patient has complaints of pain and/or instability and to determine the mechanism of injury, if any. Most patients complain of pain or instability, but some have both. An attentive examiner can glean important diagnostic information from patients' descriptions of the location of their pain (see "Pain Diagrams Aid Diagnosis," below).

Patients often report anterior knee pain, which is typically activity related and worsens when a patient negotiates stairs or runs over hilly terrain. It usually increases after the prolonged knee flexion that occurs during long car rides or sitting in class or a movie theater. Patients who have symptoms of patellar instability have had a dislocation or recurrent subluxation. True patellar subluxation occurs when the patella slips laterally out of the trochlear groove during a twisting injury. This action is different from a "giving way" or "buckling" of the knee, which more commonly represents reflex inhibition of the quadriceps from painful stimulus. Medial dislocation or subluxation is very rare and almost always is a result of failed patellofemoral realignment surgery.

The mechanism of injury is another important diagnostic clue. Patients who are injured by high-impact blunt trauma are much more likely to have suffered articular cartilage damage, particularly if the patient's flexed knee received a direct impact from, for example, the dashboard in a motor vehicle accident. If the impact occurred over the proximal tibia, the posterior cruciate ligament may have been injured, and the physical examination should include the posterior drawer test.

Patellar injuries due to relatively low-energy trauma such as may occur during walking, twisting, or dancing should raise suspicion of anatomic malalignment or flexibility deficits that may predispose the patient to instability. Similarly, insidious onset of patellofemoral complaints can be related to an anatomic predisposition or training errors that may cause soft-tissue inflammation such as patellar tendinitis. Understanding training errors or overuse patterns is essential for nonoperative management of patellofemoral disorders, since rehabilitation may include exercise and/or activity modification (see "Why Rehabilitation Requires Exercise," below).

Physical Examination: The Key Step

The key to providing a rational diagnosis and sound nonoperative treatment is the physical exam. The objectives of the exam are to confirm that the pain is patellofemoral in origin, reproduce the complaint, evaluate anatomic alignment and flexibility, and locate painful structures (1). Once the sequence is mastered, these tasks can generally be accomplished in a concise, directed exam that takes approximately 5 minutes. In patients who have unilateral complaints, comparison with the asymptomatic knee is critical, since "normal" values for physical exam variables are lacking.

Note that anterior knee pain may be referred. Particularly in children and adolescents, screening physical examination of the hip joint is important. Disorders such as Perthes disease and slipped capital femoral epiphysis can cause anterior knee pain in this age-group. In patients of all ages, lumbar radiculopathy and peripheral nerve entrapment are possible causes of anterior knee pain that can be diagnosed by a careful examiner. Examination of hip range of motion and straight leg raising should generally exclude lumbar and hip disorders.

In attempting to discern the source of the patient's pain, an important question is whether it primarily involves the soft tissues or the patellofemoral articulation itself. The examiner should consider the retinacular and synovial tissues, since they are densely innervated structures. The paratenon and the subcutaneous nerves in the patellofemoral joint area can also cause pain. Subchondral bone contains nerve fibers that may cause pain by responding to overload or increased interosseous pressure. Articular cartilage does not contain nerve endings; therefore, chondromalacia cannot be considered the true anatomic cause of anterior knee pain (2). (Chondromalacia is a surgical finding that may represent areas of hyaline cartilage trauma or aberrant loading but is not the cause of pain. For this reason physicians should abandon the use of "chondromalacia" to mean a cause of anterior knee pain and use the term only to refer to actual articular cartilage softening when it is described at surgery.) In investigating the cause of pain in patients who carry a diagnosis of chondromalacia, careful examination will usually reproduce the patient's complaints by uncovering multiple areas of tenderness in the peripatellar soft tissues.

Is There Malalignment?

To assess alignment, first observe the patient while he or she stands barefoot facing you. Observe the standing Q-angle (ie, the valgus angle) acting across the knee; angles greater than 25° in females and 20° in males are considered abnormal. Watch for torsional deformities as well as significant hindfoot pronation. If excessive pronation is present, ask the patient to turn around and stand on tiptoe; if the heel inverts, the pronation is supple. Excessive hindfoot pronation results in prolonged internal tibial rotation during gait, adversely affecting patellar mechanics. Orthoses can sometimes help control overpronation, though they are not routinely prescribed (see "Putting It All Together: The Rehab Prescription," below).

Next, observe the patient squat and stand. Note how difficult this is for the patient, as this helps determine the severity of functional deficit.

Tubercle sulcus angle and crepitus. With the patient sitting on the examining table facing you, observe whether the tibial tubercles are directly below the patellae or are displaced laterally more than 10°, indicating an increased tubercle sulcus angle (3). Lateral displacement of the tubercle suggests bony patellofemoral malalignment that may indicate an underlying predisposition to lateral patellar tracking. Next ask the patient to actively flex and extend the knee and observe the dynamic patellar tracking. Palpate and listen for crepitus as the patient moves his or her leg. Be sure to compare any crepitus with the contralateral knee, because crepitus is common in asymptomatic knees. If crepitus is clearly greater in the symptomatic knee, there may be articular cartilage damage on the patella and/or trochlea.

Is patellar mobility restricted? Before palpating for tenderness—which might make the patient uncomfortable and apprehensive, thereby making the rest of the examination more difficult—evaluate the patient's patellar mobility and lower-extremity flexibility. With the patient supine on the examination table, perform the patellar tilt test (figure 1: not shown) as a first step in evaluating patellar mobility. Compare the results with those of the contralateral knee and note any asymmetry that can be addressed during rehabilitation.

While holding the patella in corrected or neutral position of patellar tilt, attempt to displace the patella first medially and then laterally. Medial glide of one quarter or less of the patellar width suggests an abnormally tight lateral retinaculum, while medial glide of three quarters or more of its width suggests hypermobility (4). If lateral displacement produces apprehension of impending patellar subluxation or reproduces symptoms, the test is considered positive and strongly suggests patellar instability. Comparing superior and inferior patellar glide can sometimes reveal side-to-side differences as well, especially in patients who have undergone surgery.

What's Tight?

Flexibility deficits in the hip external rotators, hamstrings, quadriceps, and gastrocnemius-soleus muscle group may contribute to abnormal patellofemoral biomechanics. Diagnosing asymmetry that results from such deficits is a critical part of managing patellofemoral disorders, because asymmetry should be addressed in a treatment plan that uses stretching exercises to focus on specific muscle groups.

Hamstring and gastrocnemius flexibility. Hamstring flexibility may be estimated by measuring the popliteal angle while the patient is supine. Flex the hip to 90° and then extend the knee. Keep the patient's pelvis flat on the examination table and measure the angle created by the thigh and lower leg. While the hip and knee are flexed 90°, also check the amount of ankle dorsiflexion. When the patient's leg is brought down to the exam table, check the ankle dorsiflexion again in extension. Commonly, it will be less when the knee is extended, indicating gastrocnemius tightness.

Quadriceps flexibility. Checking quadriceps flexibility while the patient is prone (figure 2: not shown) is a crucial part of the examination. Because the rectus femoris muscle crosses the hip knee joints, prone examination is necessary to keep the hip extended during evaluation of quadriceps flexibility. Significant prone quadriceps flexibility deficits are common, especially in patients with chronic pain. If a deficit exists, a home program of quadriceps stretching can produce dramatic improvement.

Iliotibial band flexibility. The iliotibial band (ITB) connects the iliac crest to Gerdy's tubercle on the anterolateral proximal tibia and has strong attachments to the lateral patella through the lateral retinaculum. It is often tight in patients who have patellofemoral symptoms, especially in those whose patellar tilt does not correct to neutral. Ober's test assesses ITB flexibility (figure 3). While performing Ober's test, palpation of the ITB just proximal to the lateral femoral condyle during maximal stretch (ie, at the end of the test) frequently causes severe pain in patients who have excessive ITB and lateral retinacular tightness. When this is found, ITB stretches are an indispensable component of treatment. We have found that Ober's position (figure 3c) is consistently effective for treatment as well as diagnosis. Flexibility assessment is a critical part of the patellofemoral examination, because asymmetry should be addressed in the treatment plan by gearing stretching exercises to tight muscle groups.

[FIGURE 3]

What's Tender?

Careful palpation of all soft tissues in the peripatellar area is essential. Begin at the quadriceps tendon and work around the patella, palpating the central quadriceps tendon insertion, the vastus lateralis insertion, the lateral patellar retinaculum, the patellar tendon (origin, midsubstance, and tibial insertion), the medial retinaculum, the medial parapatellar plica between the medial border of the patella and the medial femoral epicondyle, and the vastus medialis obliquus muscle insertion. Note areas of tenderness and ask if the elicited tenderness reproduces the patient's pain.

To assess articular pain due to irritation of subchondral bone, the patella must be compressed into the trochlea at various degrees of flexion (figure 4: not shown). Normally the patella enters the trochlea at 10° to 15° of knee flexion, so pressure applied in full extension does not directly produce articular compression between the patella and the trochlea. As the patella enters the trochlea in early flexion, the distal portion of the patella is articulating; pain with compression in this range suggests a lesion in the distal patellar or proximal trochlear area. Conversely, as knee flexion increases, the patella is drawn distally into the trochlea, causing the area of articulation to be more proximal on the patella; pain with articular compression in flexion suggests a more proximal patellar lesion.

Other authors have described direct palpation of the lateral facet of the patella. Any tenderness noted, however, cannot necessarily be ascribed specifically to the bone, since such palpation involves the highly innervated lateral patellar retinaculum and synovial tissue as well.

Muscle Strength and Coordination

Office evaluation of quadriceps strength and motor control can only provide a rough estimate. However, measurements of thigh girth at set distances above the superior pole of the patella allow side-to-side comparison and meaningful data for follow-up evaluations.

It is also helpful to ask the patient to contract the quadriceps and to observe the timing of the vastus medialis obliquus and vastus lateralis contractions. Normally they fire simultaneously, balancing the quadriceps moment acting on the patella. In patients with anterior knee pain and patellofemoral malalignment, it is not unusual to see the vastus lateralis fire before the vastus medialis obliquus. When patients have unbalanced quadriceps contraction, treatment should include methods to improve coordination, such as biofeedback.

Radiographic Studies

Initial evaluation of patients who have patellofemoral complaints usually involves plain radiographic studies. Anteroposterior and lateral views can rule out associated and potentially serious bony conditions such as tumors, infection, or bony loose bodies. Plain radiographic patellar axial views—the sunrise or Merchant view—can demonstrate patellofemoral malalignment, but plain radiographs are less sensitive than computed tomography or magnetic resonance imaging studies in this regard. However, until thorough nonoperative management has failed, radiographic studies beyond standard plain x-rays are not indicated. Detailed radiographic measurements are not necessary to refine the nonoperative treatment of patellofemoral disorders.

Putting It All Together: The Rehab Prescription

In a busy clinical practice, the information gathered from the physical exam and radiographic studies becomes the basis for a rehabilitation prescription. For example, when the physician has observed and documented flexibility deficits and retinacular and ITB limitations that contribute to the patient's patellofemoral symptoms, the prescription should include specific stretches such as Ober's stretch—performed in the same manner as Ober's test—for ITB tightness. Physical therapists should be fully informed about the patient's condition and the rehabilitation prescription so that treatment proceeds effectively.

Taping. A rehabilitation prescription for patients with soft-tissue tightness, especially lateral patellar tilt and soft-tissue pain, can include patellar taping, which frequently reduces pain during exercise (3) and, in some patients, even allows pain-free exercise, a key to progress in patellofemoral disorders. How taping relieves pain is uncertain, but the improvement may result from alterations in local soft-tissue tensions or decompression of synovial tissue that can be pinched during motion. Some patellar braces may offer similar advantages.

Quadriceps strengthening. Quadriceps strengthening is a universal recommendation for patients with patellofemoral problems. A quadriceps strengthening program should initially avoid exercise in the arcs of motion found to be painful during articular compression and should gradually increase the range of resisted activities as the patient improves.

Although rehabilitation has traditionally begun with open-chain terminal knee extension exercise with low weight, the advantages of closed- versus open-chain exercise have been debated. Recently, Steinkamp et al (5) evaluated patellofemoral joint reaction (PFJR) force and patellofemoral joint stress (force per unit area) for leg press and leg extension exercise at intensities producing equal quadriceps tension demands. They found that closed-chain knee extension (leg press) generated less PFJR force than open-chain knee extension from approximately 45° to full extension. Conversely, at greater degrees of flexion, PFJR force was less with open-chain knee extension exercise. Thus, in some patients leg press exercise may be better tolerated than traditional open-chain knee extension exercises.

In my experience, the cocontractions and weight-bearing loads associated with closed-chain activities tend to be tolerated better than open-chain exercise in most patients with patellofemoral disorders. However, biomechanical arguments can be made in favor of open-chain exercise at different points in the range of motion, and often a trial-and-error approach works best in determining which exercises are best tolerated by individual patients.

When specific areas of tendinitis have been identified, eccentric exercise of the involved muscle group should be included (6). For example, patients with patellar tendinitis should include eccentric quadriceps strengthening. As rehabilitation progresses and pain decreases, the patient should also include sport- or work-specific exercise in his or her program.

Biofeedback. If a patient has been diagnosed as having unbalanced quadriceps contraction, biofeedback should be part of the rehabilitation prescription. This can be as simple as asking the patient to palpate the quadriceps during contraction in order to voluntarily correct the asynchronous contraction. More complex biofeedback techniques can provide visual and auditory feedback on muscle contraction and aid in quadriceps retraining.

Orthoses. The routine use of orthoses in patients with flexible hindfoot pronation and patellofemoral problems remains controversial. Because of this controversy and the cost of orthotic devices, I avoid their routine prescription initially. Use of orthoses is reasonably reserved for patients who have not responded to flexibility and strengthening routines.

Analgesics. The use of analgesics, including nonsteroidal anti-inflammatory drugs (NSAIDs), can be an important adjunct to the flexibility and strengthening prescription, because analgesics reduce pain and allow patients to pursue meaningful and successful rehabilitation. Since analgesic use does not resolve the strength and flexibility problems that underlie patellofemoral disorders, patients who are treated only with NSAIDs and rest have a high rate of recurrent symptoms.

Heat and cold. The use of heat before exercise increases soft-tissue flexibility. Ice application after exercise should be a routine part of treatment. In particular, ice massage over the areas found to be most tender on physical examination is frequently effective. Ice massage is particularly helpful where painful tissues are superficial, such as the vastus lateralis tendon insertion, the patellar tendon, and pathologic hypertrophic medial parapatellar plicae. Such localized areas of inflammation may also respond to anti-inflammatory modalities such as phonophoresis with hydrocortisone.

Patient Education and Follow-up

With the advent of limits on the number of therapy visits covered by insurance, we need to assist our patients in making the most of their visits. One way to assist is to let patients know what you expect for their therapy and also what they can expect. For example, patients who have restricted patellar mobility and iliotibial band tightness should expect hands-on stretching by therapy personnel for at least 15 to 20 minutes of each session. In addition, since data on patients' progress is increasingly important to managed-care providers, we need to document change to provide objective measures that may justify ongoing treatment. Although these steps may take time, they are worthwhile because they improve treatment specificity and quantify progress.

Physicians can and should do better than simply sending patients to therapy for "quadriceps strengthening." By doing a careful clinical evaluation of our patients' patellofemoral problems, we can provide a more scientific and rational diagnosis than "chondromalacia" or "patellofemoral pain syndrome." Improved diagnoses will foster clearer thinking and problem solving for the therapist involved and will ensure that patients who are referred to different therapists will receive consistent and appropriate rehabilitation. Such an approach will be efficient for patients, cost-effective for medical insurance carriers, and rewarding for healthcare providers.

References

  1. Post WR: Physical examination of the patellofemoral joint, in Fulkerson JP (ed): Disorders of the Patellofemoral Joint, ed 3. Baltimore, Williams and Wilkins, 1997
  2. Radin EL: A rational approach to the treatment of patellofemoral pain. Clin Orthop 1979;144(Oct):107-109
  3. McConnell J: The management of chondromalacia patellae: a long term solution. Austr J Physiother 120216;32:215-223
  4. Kolowich PA, Paulos LE, Rosenberg TD, et al: Lateral release of the patella: indications and contraindications. Am J Sports Med 1990;18(4):359-365
  5. Steinkamp LA, Dillingham MF, Markel MD, et al: Biomechanical considerations in patellofemoral joint rehabilitation. Am J Sports Med 1993;21(3):438-444
  6. Stanish WD, Rubinovich RM, Curwin S: Eccentric exercise in chronic tendinitis. Clin Orthop 120216;208(Jul):65-68


Pain Diagrams Aid Diagnosis

The use of a simple, patient-drawn pain diagram may help clarify a vague, frustrating, and complicated history in a patient with patellofemoral pain. One study (1) used a standard knee diagram divided into nine zones to correlate areas of pain noted by patients with areas of tenderness found by physicians on physical examination. Patients who complained of anterior knee pain marked areas of pain on the diagram before being evaluated. After the physical exam, the physician marked areas of tenderness on a separate, identical diagram. The patient-drawn diagrams correlated fully or partially with the physician-drawn diagrams in 88% of cases. The association of pain and tenderness in the nine anatomic zones was very consistent. Even more clinically relevant was the finding that 86% of the sites where the patient did not indicate pain correctly predicted the absence of tenderness.

These findings are important because they show that a focused physical exam can reproducibly distinguish anatomic sites likely to be involved in generating the patient's pain. Identifying these tender structures and associated strength and flexibility imbalances forms the basis of a thorough, rational nonoperative rehabilitation program.

Reference

  1. Post WR, Fulkerson J: Knee pain diagrams: correlation with physical examination findings in patients with anterior knee pain. Arthroscopy 1994;10(6):618-623


Why Rehabilitation Requires Exercise

Tissues in the anterior knee most often become painful as a result of tissue overload. This overload may be acute—as in blunt anterior knee trauma or a high-energy patellar dislocation—or may be the result of repetitive overuse. Overuse may result from training errors and underlying malalignment, which lead to soft-tissue microinjury. If a training schedule does not permit time to heal such microinjury, continued strenuous activity can result in overload and microfailure. Though the exact mechanism by which overload produces pain is uncertain, strength and flexibility imbalances are almost always clinically important features of this cycle.

For patients and athletes to return to their desired activity level, their rehabilitated strength and flexibility must often exceed the preinjury level, since that level was inadequate to support the original loads imposed. The patient must temporarily decrease and/or modify the loading conditions of the knee and work toward restoration of adequate strength and flexibility to reach his or her goals safely. Rest and medication can certainly decrease pain, but they cannot improve the ability to perform at the desired level. Thus, when treatment features only rest and medication, recurrence is likely when patients resume their activities.


Dr Post is an assistant professor and chief of the section of sports medicine and shoulder surgery in the Department of Orthopedics at West Virginia University School of Medicine in Morgantown, West Virginia. Address mail to William R. Post, MD, University of West Virginia School of Medicine, Box 9196, Morgantown, WV 26506-9196; e-mail to [email protected].


RETURN TO JANUARY 192021 TABLE OF CONTENTS

HOME  |   JOURNAL  |   PERSONAL HEALTH  |   RESOURCE CENTER  |   CME  |   ADVERTISER SERVICES  |   ABOUT US  |   SEARCH


The McGraw-Hill Companies Gradient

Copyright (C) 192021. The McGraw-Hill Companies. All Rights Reserved
Privacy Policy.   Privacy Notice.