Meniscal Tears Case File

Meniscal Tears Case File

Eugene C. Toy, MD, Andrew J. Rosenbaum, MD, Timothy T. Roberts, MD, Joshua S. Dines, MD

CASE 23

A 28-year-old otherwise healthy man presents to the office complaining of pain and swelling in his right knee. He reports that he first noticed pain when he pivoted off of the right leg during a pickup football game 2 days earlier. He was able to finish playing the game. He did not recall an audible “pop” or immediate swelling. The effusion developed later that evening. He denies any sense of instability. The patient denies any other medical or surgical history. On physical exam of the right knee, there are no abrasions or ecchymosis. There is a mild to moderate effusion and tenderness to palpation along the medial joint line. There is no pes anserine, lateral joint line, or other bony tenderness. He has complete, but painful, range of motion. He is stable to varus and valgus stress at 0 and 30 degrees. He has negative Lachman, anterior, and posterior drawer tests. McMurray and Apley tests are positive. He is neurovascularly intact distally.

► What is your most likely diagnosis?

► What should be included in the differential diagnosis?

► What is your next diagnostic step?

► What is the next step in therapy?

ANSWER TO CASE 23:

Meniscal Tears                              

Summary: A 28-year-old healthy man who sustained a right knee twisting injury during a pickup football game presents with right knee pain. His exam is significant for a moderate effusion, medial joint line tenderness, positive McMurray and Apley tests, and a stable ligamentous exam.

• Most likely diagnosis: Tear of the medial meniscus.
• Differential diagnosis: Osteoarthritis, loose body, patellar subluxation or dislocation, osteochondritis dissecans, articular cartilage lesions, tibial plateau fractures, ligamentous injury, pes anserine bursitis, and fat pad impingement syndrome.
• Next diagnostic step: Plain radiographs of the knee, followed by magnetic resonance imaging (MRI).
• Next step in therapy: Arthroscopic partial meniscectomy, with resection to a stable, smooth rim of meniscus. Meniscal repair is also a possibility, depending on the location of the tear.

ANALYSIS

Objectives

1. Understand the typical patient demographics and mechanism of injury associated with meniscal tears.
2. Be familiar with the treatment options for meniscal pathology.

Considerations

This is a 28-year-old man who presents after an injury to his right knee sustained during a pickup football game. The history and physical exam are very typical for meniscal pathology. This includes his twisting mechanism of injury, pain, lateonset joint effusion (versus a sudden-onset effusion, which may indicate isolated or concomitant anterior cruciate ligament tear), and medial joint line tenderness. Additionally, 2 meniscus-specific tests, the McMurray and Apley tests, are positive ( Figure 23–1 ). Although the patient’s history and examination are consistent with an acute meniscal injury, the orthopaedist must also be familiar with patients presenting with symptoms indicative of the more chronic “degenerative” and “complex” meniscal tears. In the setting of a meniscal tear, radiographs and potentially MRI should be obtained. Treatment, which consists of either operative or more conservative measures, is patient specific, with multiple factors determining the ideal approach.

Figure 23–1. Tests for tear of the medial meniscus. (A) McMurray test. (B) Apley test. (C) Childress

test. (Reproduced, with permission, from LeBlond RF, DeGowin RL, Brown DD. DeGowin’s Diagnostic Examination. 9th ed. New York, NY: McGraw-Hill; 2009:Fig. 13-24.)

APPROACH TO:

Meniscal Tears                                 

DEFINITIONS

MENISCI (MEDIAL AND LATERAL): Fibrocartilaginous (predominantly type I collagen) structures within the knee joint that increase contact area, distribute load (50%-70% in extension and 85%-90% in flexion), absorb shock, and play a role in joint stability and proprioception. Removing the entire meniscus decreases the overall knee contact area and subsequently results in increased stress throughout the knee, pain, and degenerative joint disease. The medial meniscus is larger and more oblong than the lateral meniscus. It is also an important secondary stabilizer to anterior tibial translation and is thus essential for stability in an anterior cruciate ligament (ACL)-deficient knee.

VASCULAR ZONES: The meniscus is divided into thirds based on vascularity. The peripheral third is the most vascularized and deemed the “red-red” zone. The middle third, referred to as the “red-white” zone, has an intermediate vascularity. The inner third, or the “white-white” zone, is avascular.

MCMURRAY TEST: Flexion and rotation of the knee. To test the medial meniscus, the examiner flexes the knee, places a hand on the medial or posteromedial joint line of the knee, and then brings the knee from flexion to extension while externally rotating the leg. To test the lateral meniscus, the examiner places a hand on the lateral joint line and applies an internal rotation force to the leg. A positive test is found with a palpable “clunk” at the joint line and occurs as the torn meniscus displaces. It is the most specific test (98%) for a meniscal tear but is only 15% sensitive.

APLEY TEST: The patient is prone with the knee flexed to 90 degrees. A downward compressive force is applied by the examiner through the lower leg while laterally rotating the lower leg. Pain during this maneuver is indicative of a meniscal injury.

CLINICAL APPROACH

Etiology

Meniscal tears have an incidence of 60 to 70 cases per 100,000 people per year and occur with a male predominance of approximately 3:1. Tears can be divided into 2 etiologies: those occurring in younger patients and caused by an acute, twisting, or rotational force and those seen in older patients with menisci vulnerable to injury secondary to underlying degenerative changes of the knee.

Diagnosis

A thorough history and physical exam is the first step in diagnosis, and patients with meniscal pathology may describe an acute injury or a more indolent onset of symptoms. Patients may have recurring knee effusions, medial or lateral joint line tenderness, posterior knee pain, and/or mechanical symptoms, such as locking and clicking.

    The physical exam includes observing the patient’s gait, knee alignment, symmetry, and use of assistive devices. Palpation and evaluation of the patella for tenderness and laxity, palpation of the medial and lateral joint lines, the pes anserinus, medial and lateral collateral ligaments, tibial tubercle, and Gerdy tubercle should also be done. Range of motion (both hip and knee) must be assessed and compared with the contralateral side, as should a ligamentous (ACL, posterior cruciate ligament, medial collateral ligament, lateral collateral ligament) exam. Of note, a torn lateral meniscus is the most commonly associated meniscal injury in the setting of an acute ACL tear, whereas the medial meniscus is most commonly torn in the setting of a knee with a chronic ACL deficiency. Crepitus or locking should also be noted.

    Two tests commonly used for the evaluation of meniscus-specific pathology are the McMurray and Apley tests ( Figure 23–1 ). Both have a high specificity but poor sensitivity. Joint line tenderness remains the most sensitive test (74%) for a meniscal injury. Childress sign (Squat test) can also be used and is positive when the patient, who attempts to squat and walk like a duck, feels pain, is unable to squat all the way down, and feels a snap or click from the knee (Figure 23–1).

    Plain radiographs should be the first imaging obtained. This includes bilateral weightbearing posteroanterior (PA) views, 45-degree flexion PA views, 20 degrees of flexion in patellofemoral view, and a lateral radiograph. MRI is used to confirm the physical exam findings concerning for a meniscal tear and will identify the tear pattern and displacement (Figure 23–2). It has an accuracy of approximately 95% in diagnosing tears.

TREATMENT

Treatment of meniscal tears is patient- and tear-specific and varies from nonsurgical, conservative measures to resection, repair, or transplant. Nonsurgical treatment includes ice, nonsteroidal anti-inflammatory drugs (NSAIDs), intraarticular corticosteroid injections, and physical therapy. Indications include asymptomatic, partial-thickness tears less than 5 to 10 mm in length.

Figure 23–2. Medial meniscal tear on the MRI frontal view, seen as a small white line through the

black meniscus. (Courtesy of Heidi Chumley, MD)

    Surgical options include meniscal repair, open and arthroscopic partial meniscectomy, and meniscal transplant. Meniscal repair is reserved for acute tears in the “red-red” zone of a nondegenerative meniscus. Arthroscopic partial meniscectomy is the current standard of care for most tears and can relieve pain and eliminate mechanical blocks to motion while preserving as much healthy tissue as possible. Indications include symptomatic radial or longitudinal tears, patients who have failed nonoperative management, displaced bucket-handle tears, tears creating a mechanical block, and symptomatic discoid lateral meniscus. Patients with severe degenerative joint disease may be candidates for knee replacement. Meniscal allograft transplant is indicated in a select group of young patients who have failed prior partial or total meniscectomy with minimal degenerative changes.

Complications

Because the meniscus is responsible for the distribution of load and shear forces across the knee, the initial meniscal injury as well as its management (ie, partial or total meniscectomy) can increase the contact pressures between the femur and tibia, accelerating the progression of degenerative joint disease. Additionally, repairs can fail and infections can occur, either postoperatively or after an intraarticular injection.

COMPREHENSION QUESTIONS

23.1 A college football player reports pain along the medial joint line with intermittent locking and an inability to fully extend the knee after a twisting injury to his right knee. He has a negative Lachman exam and a positive McMurray test. What is the most likely diagnosis?

A. Longitudinal vertical lateral meniscus tear

B. ACL injury

C. PCL injury

D. Bucket-handle medial meniscus tear

E. None of the above

23.2 Which of the following physical examination maneuvers is the most sensitive in the diagnosis of a medial meniscus tear?

A. Apley test

B. McMurray test

C. Medial joint line tenderness

D. Lachman test

E. Pain with valgus stress

23.3 A 20-year-old soccer player sustained a twisting injury to his knee approximately 1 month ago. He complains of continued medial-sided knee pain with occasional locking and catching. MRI findings are consistent with a tear of the medial meniscus. What physical exam finding is classically seen with this injury?

A. Positive anterior drawer test

B. No end point with varus stressing of the knee

C. Palpable pop when bringing the flexed knee to extension while internally rotating the leg

D. Palpable pop when bringing the flexed knee to extension while externally rotating the leg

ANSWERS

23.1 D. The patient has a bucket-handle medial meniscus tear after an acute injury. Such tears are associated with knee locking and a block to full extension. These tears are more common in young patients, often associated with ACL tears, and are the most commonly missed meniscal tear on MRI.

23.2 C. Although the McMurray and Apley grind tests are commonly used to aid in diagnosis, joint line tenderness to palpation has been shown to be the most sensitive physical exam finding for meniscal injury.

23.3 D. A positive McMurray test in the setting of a medial meniscus tear is the presence of a palpable pop as the knee is brought from a flexed to extended position while externally rotating the leg. C describes a positive McMurray test for a lateral meniscus tear. A and B do not describe tests for meniscal pathology, but instead the anterior cruciate ligament and the lateral collateral ligament, respectively.

    CLINICAL PEARLS    

► Meniscal tears are most accurately diagnosed by history and physical exam, with joint line tenderness being the most sensitive indicator of a meniscal tear. ► Two tests commonly used for the evaluation of meniscus-specific pathology are the McMurray and Apley tests, both of which have a high specificity and low sensitivity. ► MRI has an accuracy of approximately 95% in diagnosing tears. Asymptomatic, partial-thickness tears less than 5 to 10 mm in length are typically treated nonoperatively. ► Indications for arthroscopic partial meniscectomy include symptomatic radial or longitudinal tears, patients who have failed nonoperative management, displaced bucket-handle tears, tears creating a mechanical block, and symptomatic discoid lateral meniscus.

REFERENCES

Douglas JA, Sgaglione NA. Meniscal injuries. In: Schepsis AA, Busconi BD, eds. Orthopaedic Surgery Essentials: Sports Medicine. Philadelphia, PA: Lippincott Williams & Wilkins; 2006. 

Greis PE, Bardana DD, Holmstrom MC, Bruks RT. Meniscal injury: I. Basic science and evaluation. J Am Acad Orthop Surg. 2002;10:168-176. 

Ryzewicz M, Peterson B, Siparsky PN, Bartz RL. The diagnosis of meniscus tears: the role of MRI and clinical examination. Clin Orthop Relat Res. 2007;455:124-133.

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