Nontraumatic knee pain: A diagnostic & treatment guide

CASE › Jane T, age 42, comes to see you because of right knee pain that she’s had for about 6 months. She denies any trauma. Ms. T describes the pain as vague and poorly localized, but worse with activity. She says she started a walking/running program 9 months ago, when she was told she was overweight (body mass index, 29). She has lost 10 pounds since then, Ms. T says, and hopes to lose more by continuing to exercise. upon further review, you find that Ms. T has had increasing pain while ascending and descending stairs and that the pain is also exacerbated when she stands after prolonged sitting.

If Ms. T were your patient, what would you include in a physical examination and how would you diagnose and treat her?

Knee pain is a common presentation in primary care. While traumatic knee pain is frequently addressed in the medical literature, little has been written about chronic nontraumatic nonarthritic knee pain like that of Ms. T. Thus, while physical exam tests often lead to the correct diagnosis for traumatic knee pain, there is limited information on the use of such tests to determine the etiology of chronic knee pain.

This review was developed to fill that gap. In the pages that follow, we provide general guidance on the diagnosis and treatment of chronic nontraumatic knee pain. The conditions are presented anatomically—anterior, lateral, medial, or posterior—with common etiologies, history and physical exam findings, and diagnosis and treatment options for each (TABLE).^1-31

Anterior knee pain

Patellofemoral pain syndrome

Patellofemoral pain syndrome is the most common cause of anterior knee pain. Taping or bracing—along with physical therapy—may help reduce the pain.
Patellofemoral pain syndrome (PFPS), the most common cause of anterior knee pain, is a complex entity with an etiology that has not been well described.² The quadriceps tendon, medial and lateral retinacula, iliotibial band (ITB), vastus medialis and lateralis, and the insertion of the patellar tendon on the anterior tibial tubercle all play a role in proper tracking of the patellofemoral joint; an imbalance in any of these forces leads to abnormal patellar tracking over the femoral condyles, and pain ensues. PFPS can also be secondary to joint overload, in which excessive physical activity (eg, running, lunges, or squats) overloads the patellofemoral joint and causes pain.

Risk factors for PFPS include strength imbalances in the quadriceps, hamstring, and hip muscle groups, and increased training, such as running longer distances.^4,32 A recent review showed no relationship between an increased quadriceps (Q)-angle and PFPS, so that is no longer considered a major risk factor.⁵

Diagnosis. PFPS is a diagnosis of exclusion, and is primarily based on history and physical exam. Anterior knee pain that is exacerbated when seated for long periods of time (the “theater sign”) or by descending stairs is a classic indication of PFPS.¹ Patients may complain of knee stiffness or “giving out” secondary to sharp knee pain and a sensation of popping or crepitus in the joint. Swelling is not a common finding.²

A recent meta-analysis revealed limited evidence for the use of any specific physical exam tests to diagnose PFPS. But pain during squatting and pain with a patellar tilt test were most consistent with a diagnosis of PFPS. (The patellar tilt test involves lifting the lateral edge of the patella superiorly while the patient lies supine with knee extended; pain with <20° of lift suggests a tight lateral retinaculum). Conversely, the absence of pain during squatting or the absence of lateral retinacular pain helps rule it out.² A physical exam of the cruciate and collateral ligaments should be performed in a patient with a history of instability. Radiography is not needed for a diagnosis, but may be considered if examination reveals an effusion, the patient is age 50 years or older, or no improvement occurs after 8 to 12 weeks of treatment.³³