What is the diagnosis?

The patient is diagnosed with a radial tear of the medial meniscus.

Image 1. Coronal view MRI of right knee. There is a vertical cleft of increased signal intensity (green label) contacting the meniscal surface, creating a 6mm gap between the torn edges of the meniscus, consistent with a radial tear.  

• Pearl: Radial tears occur from shear forces on the knee. They disrupt the longitudinal collagen fibers of the meniscus [1]. They arise from the free edge of the meniscus, and when reaching the peripheral margins, they can result in a gap between the torn edges of the meniscus, as seen in the imaging above. 

What is the mechanism of injury?

Meniscus tears are often due to rotational or shearing forces across the tibiofemoral joint, especially when there is an increased axial load through the menisci [2]. This often includes activities that involve rapid acceleration/deceleration or change of direction, as in the case of this patient who was twisting to put her grandchildren to bed. 

• Pearl: Although meniscus tears are often associated with high impact activities involving rapid changes in direction, such as soccer, football, basketball, or military-related physical activity, they can often occur in non-active adults, especially those over age 40 and with pre-existing osteoarthritis of the knee [2].

What physical exam findings are expected?

History: There should be high suspicion for a meniscus (and/or ACL) tear when the patient describes a sensation of a “pop” at the time of injury, followed by immediate swelling of the knee. Patients may also describe the sensation of locking, clicking, catching, or feeling the knee “give way.” 

Physical Exam Findings:

• Inspection: of the knee for edema

• Palpation: for tenderness along the joint line

• Special tests for detection of meniscus tears include: positive Thessaly test, McMurray’s test, and Apley’s compression test. 

• Pearl: Patients can develop mechanical symptoms with a bucket handle meniscus tear in which the meniscus is flipped on itself and limits the patient from fully straightening the knee.

Which imaging modalities can be used?

Although an X-ray is initially obtained to evaluate for degenerative changes or other bony pathologies, MRI is the gold standard to diagnose and characterize meniscus tears [2]. 

What is the management in the ED?

In the ED, the primary treatment is symptom management if x-ray is negative for acute concomitant pathology. These patients do not require emergent orthopedic consultation and can be instructed to follow up in the outpatient setting with a primary care sports medicine physician or orthopedics. 

What is the management in the Family Medicine Clinic? When do you consult Orthopedics? What do you do to follow up?

In the Family Medicine Clinic, the primary care physician should first prioritize a thorough history and physical examination as well as imaging to both diagnose and characterize the meniscus tear.

Meniscus tears in the “red” zone, or the outer one-third of the meniscus that has a rich blood supply, can often heal on their own. Tears in the inner two-thirds of the meniscus, or the “white” zone without significant blood supply, may require surgical management if they do not respond to conservative treatment [2].

The primary care physician should play an involved role in nonsurgical, conservative treatment of meniscal tears. This involves RICE (rest, ice, compression, elevation), oral analgesics and NSAIDs, short term bracing or knee sleeves for protection and compression, and a referral to at least 6 weeks of physical therapy [3]. Corticosteroid injections are also an option in the outpatient setting. 

For patients with persistent pain and mechanical symptoms resistant to conservative treatment, Orthopedics should be consulted. If a patient is a surgical candidate, knee arthroscopy is performed where meniscal repair vs meniscectomy is considered. 

For some patients, a perioperative risk optimization visit may be required from the patient’s PCP before the patient is optimized for surgery. The PCP may use any of the three surgical calculators (RCRI, MICA, or ACS-NSQIP) as part of the perioperative medicine evaluation [4]. The PCP should continue to follow up with the patient’s rehabilitation process after surgical intervention.