Meniscus Injuries Treatment & Management

Meniscal injuries may be the most common knee injury. Meniscus tears (see the image below) are sometimes related to trauma, but significant trauma is not necessary. A sudden twist or repeated squatting can tear the meniscus.

Magnetic resonance imaging scan showing a torn medial meniscus.

Signs and symptoms

Most meniscal injuries can be diagnosed by obtaining a detailed history. Important points to address include the following:

• Mechanism of injury (eg, twisting, squatting, changes in position)
• Pain (commonly intermittent and usually localized to the joint line)
• Mechanical complaints (eg, clicking, catching, locking, pinching, or a sensation of giving way)
• Swelling (usually delayed, sometimes absent; degenerative tears often manifest with recurrent effusions)

Physical findings that are significant in the examination of a patient with a possible meniscus injury include the following:

• Joint line tenderness (77-86% of patients with a meniscal tear)
• Effusion (~50% of patients presenting with a meniscal tear)
• Impaired range of motion – A mechanical block to motion or frank locking can occur with displaced tears; restricted motion commonly results from pain or swelling

Provocative maneuvers that may elicit characteristic results in the presence of a meniscal tear include the following:

• McMurray test – Pain or a reproducible click
• Steinmann test – Asymmetric pain with external (medial meniscus) or internal (lateral meniscus) rotation
• Apley test – Pain at the medial or lateral joint
• Thessaly test – Pain or a locking or catching sensation at the medial or lateral joint line
• Similar tests, including those that elicit the Bragard, Böhler, Payr, Merke, Childress, and Finochietto signs

See Presentation for more detail.

Diagnosis

Imaging studies that may be considered include the following:

• Plain radiography – Anteroposterior weight-bearing view, posteroanterior 45° flexed view, lateral view, and Merchant patellar view
• Arthrography – Once the standard imaging study for meniscal tears but now largely supplanted by magnetic resonance imaging (MRI)
• MRI – Criterion standard for imaging meniscus pathology and all intra-articular disorders

Abnormal meniscal signals on MRI are classified into the following groups:

• Grade I – Small area of increased signal within the meniscus
• Grade II – Linear area of increased signal that does not extend to an articulating surface
• Grade III – Abnormal increased signal that reaches the surface or edge of the meniscus (indicative of meniscal tearing)
• Root tears – Meniscal extrusion of at least 3 mm in the mid-coronal plane^[1]

In competent hands, arthroscopy is the best tool for meniscal tear diagnosis, with sensitivity, specificity, and accuracy approaching 100%. Being both therapeutic and diagnostic, it offers the option of immediate treatment of most disorders.

See Workup for more detail.

Management

Conservative treatment should be attempted in all but the most severe cases. In the acute phase, such treatment may include the following:

• Home physical therapy program
• Simple rest with activity modification
• Ice
• Nonsteroidal anti-inflammatory drugs (NSAIDs)

If conservative treatment does not lead to resolution, surgical treatment is considered. Surgical options (arthroscopic or open) include the following:

• Partial meniscectomy – The treatment of choice for tears in the avascular portion of the meniscus or complex tears that are not amenable to repair
• Meniscus repair – Recommended for tears that occur in the vascular region (red zone or red-white zone), are longer than 1 cm, root tears, involve greater than 50% of the meniscal thickness, and are unstable to arthroscopic probing
• In cases of previous total or subtotal meniscectomy, meniscus transplantation – A relatively new procedure for which specific indications and long-term results have not yet been clearly established

In the recovery phase, physical therapy may involve the following:

• Partial meniscectomy – Low-impact or nonimpact workouts on postoperative day 1, advancing rapidly to preoperative activities; this can usually be accomplished without formal physical therapy, but such therapy should be initiated if deficits persist
• Meniscus repair – More intensive rehabilitation; one option is avoidance of weight bearing for 4-6 weeks, with full motion encouraged; the authors prefer to allow full weight bearing with the knee braced and locked in full extension for 6 weeks, while encouraging full motion when the knee is not bearing weight

Medical therapy can be used during trials of nonoperative management with associated rest, ice, and a rehabilitation program. If surgical treatment is indicated, medical therapy is valuable in postoperative management.

Rehabilitation Program

Physical Therapy

A home physical therapy program or simple rest with activity modification, ice, and nonsteroidal anti-inflammatory drugs (NSAIDs) is the nonoperative management of possible meniscus tears. The physical therapy program goals are to minimize the effusion, normalize gait, normalize pain-free range of motion, prevent muscular atrophy, maintain proprioception, and maintain cardiovascular fitness. Choosing this course of treatment must include consideration of the patient's age, activity level, duration of symptoms, type of meniscus tear, and associated injuries such as ligamentous pathology. A trial of conservative treatment should be attempted in all but the most severe cases, such as a locked knee secondary to a displaced bucket-handle tear.

Medical Issues/Complications

The main complication at this stage of treatment is the absence of healing and failure of symptoms to resolve. The natural history of a short (< 1 cm), vascular, longitudinal tear is often one of healing or resolution of symptoms. Stable tears with minimal displacement, degenerative tears, or partial-thickness tears may become asymptomatic with nonoperative management.^[19]

Most meniscal tears do not heal without intervention. If conservative treatment does not allow the patient to resume desired activities, his or her occupation, or a sport, surgical treatment is considered. Surgical treatment of symptomatic meniscal tears is recommended because untreated tears may increase in size and may abrade articular cartilage, resulting in arthritis (see Treatment, Acute Phase, Surgical Intervention).

Surgical Intervention

If symptoms persist, if the patient cannot risk the delay of a potentially unsuccessful period of observation (eg, elite athletes), or in cases of a locked knee, surgical treatment is indicated.^[20]

The basic principle of meniscus surgery is to save the meniscus.^[21] Tears with a high probability of healing with surgical intervention are repaired. However, most tears are not repairable and resection must be restricted to only the dysfunctional portions, preserving as much normal meniscus as possible.

Surgical options include partial meniscectomy or meniscus repair (and in cases of previous total or subtotal meniscectomy, meniscus transplantation). Arthroscopy, a minimally invasive outpatient procedure with lower morbidity, improved visualization, faster rehabilitation, and better outcomes than open meniscal surgery, is now the standard of care. One study found that arthroscopic pullout repair of a medial meniscus root tear provided better results than partial meniscectomy.^[22]

Partial meniscectomy is the treatment of choice for tears in the avascular portion of the meniscus or complex tears that are not amenable to repair. Torn tissue is removed, and the remaining healthy meniscal tissue is contoured to a stable, balanced peripheral rim.

Meniscus repair is recommended for tears that occur in the vascular region (red zone or red-white zone), are longer than 1 cm, are root tears, involve greater than 50% of the meniscal thickness, and are unstable to arthroscopic probing. A stable knee is important for successful meniscus repair and healing. Thus, associated ligamentous injuries must be addressed.

The most commonly associated ligamentous disruption is complete tear of the ACL, which must be reconstructed to prevent recurrent meniscal tears. Fortunately, the increased blood and growth factors in the knee during meniscal repair combined with cruciate reconstruction significantly improves the outcome of the meniscal repair. In ACL-intact knees with isolated meniscal tears, healing rates are less than those in ACL-reconstructed knees, but they are higher than those in ACL-deficient knees.

The principles of repair include smoothing and abrading the torn edges and bordering synovium to promote bleeding and healing. Likewise, needle trephination of the meniscal body (poking holes to create vascular channels) can be performed.

Meniscus repair fixation techniques are numerous and variable. Fixation can be accomplished with outside-in, inside-out, or all-inside arthroscopic procedures.^{[6, 23, 24, 25]} The outside-in and inside-out methods are usually performed with sutures and require additional incisions. Suture repair can be accomplished with vertical or horizontal stitches. The all-inside method is very popular, and a plethora of commercially available meniscus repair devices are available (eg, biodegradable arrows or darts, sliding knot sutures with extracapsular anchor fixation).

Over the past decade, there have been multiple laboratory and clinical studies investigating the efficacy and safety of third- and fourth-generation all-inside devices. The current literature on the efficacy of the all-inside technique is best summarized by 3 independent systematic reviews.^{[26, 27, 28]}

In a 2007 systematic review of the all-inside technique, Lozano et al reported a failure rate of 0-43%.^[26] There were no significant differences in efficacy noted among the different all-inside devices included in the review.

In a 2012 systematic review that compared the all-inside and outside-in techniques in isolated meniscal tears (eg, without concomitant ACL reconstruction), Grant et al reported the failure rates of the all-inside and outside-in techniques were 19% and 17%, respectively.^[27] The final Lysholm and Tegner activity scores were similar between the techniques.

In the same year (2012), Nepple et al provided the most comprehensive systematic review of all meniscal repair techniques to date, in which they pooled outcomes data at greater than 5 years of these procedures, and observed no difference in outcome among the open, outside-in, inside-out, and all-inside techniques.^[28] The pooled clinical failure rate of open repair was 23.1%; inside-out, 22.3%; outside-in, 23.9%; and all-inside, 24%.

Prospective, randomized controlled trials are lacking; ultimately, they are necessary to determine the most effective method of surgical repair.

In recent years, meniscal root tears have been investigated as a unique type of meniscal tear that requires special attention. Multiple biochemical studies have shown that the joint contact mechanics of a posterior root tear is almost identical to that of a complete meniscectomy, and that repair restores normal mechanics.^{[29, 30]} The global loss of circumferential hoop tension caused by root tears is believed to be the source of the increased joint contact forces observed in affected patients. Therefore, there has been an increased focus to surgically repair root tears more aggressively.

Surgical repair of root tears, however, poses a unique challenge in that the meniscus must be repaired to bone. The root is fixed to bone by either arthroscopically-assisted bone suture anchors (all-inside technique) or an intraosseous suture technique ("pullout technique").^{[31, 32, 33, 34, 35]}

In a study comparing the results of the pullout technique with partial meniscectomy, investigators showed that repair improved functional outcomes and decreased progression of arthritic changes.^[36] A separate study that compared the results of the all-inside and pullout techniques showed no difference in function or repair characteristics between the 2 techniques^[37] : Complete structural healing was observed in 86% of patients who underwent the all-inside technique and 65% of those who underwent the pullout technique (P >0.05). In another study, investigators assessed the results of the all-inside repair and reported significant improvement in the amount of sagittal extrusion; however, improvement of coronal extrusion was not observed.^[38]

Future prospective, randomized controlled trials are needed to compare the effectiveness of these techniques with respect to healing rates and prevention of arthritic changes.

Human allograft meniscal transplantation is a relatively new procedure but is being performed increasingly frequently. Specific indications and long-term results have not yet been clearly established. Meniscus transplantation requires further investigation to assess its efficacy in restoring normal meniscus function and preventing arthrosis.