From the Guidelines
Physical examination of the right knee reveals a palpable mass in the medial region, with the knee demonstrating full range of motion and no signs of joint effusion, erythema, or increased warmth. The palpable mass is approximately 2 cm in diameter, firm, non-tender, and immobile, located along the medial joint line, adjacent to the medial collateral ligament. Ligamentous testing shows stability of the anterior and posterior cruciate ligaments with negative Lachman and drawer tests 1. The medial and lateral collateral ligaments are intact with no laxity on valgus and varus stress testing. McMurray's test is negative for meniscal pathology. Patellar tracking is normal with no apprehension. Muscle strength is 5/5 in all muscle groups around the knee joint. Neurovascular status is intact with normal sensation, 2+ popliteal and dorsalis pedis pulses, and appropriate capillary refill. The mass does not appear to affect knee function but warrants further evaluation with imaging studies such as ultrasound or MRI to determine its nature, as it could represent a meniscal cyst, ganglion, or other soft tissue mass 1. Key points to consider in the evaluation of this palpable mass include:
- Initial imaging study with radiographs or ultrasound for superficial masses 1
- Further evaluation with MRI or CT if initial imaging is nondiagnostic 1
- Consideration of the patient's medical history and physical examination findings to guide the diagnostic workup 1
From the Research
Physical Assessment of the Right Knee with a Palpable Mass in the Medial Region
The physical assessment of the right knee with a palpable mass in the medial region may involve several key components, including:
- Inspection: Visual examination of the knee to identify any swelling, redness, or deformity.
- Palpation: Gentle pressing of the skin to identify the location and size of the palpable mass, as well as any tenderness or warmth.
- Range of motion: Assessment of the knee's ability to flex and extend, including any limitations or pain.
- Special tests: Performance of specific tests, such as the McMurray test or Apley test, to evaluate meniscal function and potential tears.
Potential Causes of the Palpable Mass
The palpable mass in the medial region of the knee may be caused by a meniscal cyst, which is a fluid-filled structure that can form in association with a meniscal tear 2, 3. Meniscal cysts are more common in the medial compartment than in the lateral compartment, and are often associated with horizontal meniscal tears 4, 2.
Diagnostic Considerations
Imaging studies, such as magnetic resonance imaging (MRI) or musculoskeletal ultrasound, may be necessary to confirm the diagnosis of a meniscal cyst and to evaluate the extent of any associated meniscal tear 5, 6. MRI can be used to distinguish meniscal cysts from other fluid collections that may mimic meniscal cysts, and can provide detailed information about the location, size, and morphology of the cyst 3.
Associated Findings
The presence of a meniscal cyst may be associated with other findings, such as:
- Meniscal tears: Horizontal meniscal tears are commonly associated with meniscal cysts 4, 2.
- Joint line tenderness: The patient may experience tenderness or pain along the joint line, particularly in the medial compartment.
- Limited range of motion: The patient may have limited flexion or extension of the knee due to pain or mechanical obstruction caused by the cyst.