Management of degenerative meniscal tears and the role of surgeryBMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h2212 (Published 04 June 2015) Cite this as: BMJ 2015;350:h2212
- Rachelle Buchbinder, director, professor of clinical epidemiology12,
- Ian A Harris, professor of orthopaedic surgery3,
- Andrew Sprowson, associate professor of trauma and orthopaedics4
- 1Monash Department of Clinical Epidemiology, Cabrini Institute, Malvern, VIC 3144, Australia
- 2Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, The Alfred Centre, Melbourne, Vic, Australia
- 3Whitlam Orthopaedic Research Centre, Ingham Institute for Applied Medical Research, South Western Sydney Clinical School, University of New South Wales, Liverpool, NSW, Australia
- 4Warwick Clinical Trials Unit, Warwick University, Coventry, UK
- Correspondence to: R Buchbinder
The bottom line
Degenerative meniscal tears are common and correlate poorly with symptoms; no clinical features are diagnostic
Avoid routine magnetic resonance imaging in primary care unless the patient has a locked knee (sudden inability to fully extend) or serious disease is suspected
First line treatment comprises non-operative modalities, such as education, self management, exercise, weight loss if overweight or obese, walking aids if indicated, paracetamol, non-steroidal anti-inflammatory drugs, and intra-articular glucocorticoids. Current evidence does not support a role for arthroscopic debridement, washout, or partial meniscectomy
How patients were involved in the creation of this article
Eight patients (four each from the UK and Australia) read the manuscript and provided comments. They made some suggestions for improving clarity in the advice for patients box, which we have incorporated.
The use of knee arthroscopy to treat degenerative meniscal tears is well established worldwide. However, with the advent of high quality randomised controlled trials questioning its value, observations that these lesions are usually asymptomatic, and recognition that arthroscopy is a “difficult habit to break,”1 it is timely to review the best evidence based management of these tears and reconsider the role of surgery.
Classification of meniscal tears
The menisci are two largely aneural crescent shaped discs of fibrocartilage, which sit within the lateral and medial compartments of the knee joint. They evenly transfer load across the joint, absorb shock during dynamic movement, and lubricate and help stabilise the joint. Injury, degeneration, or surgical removal of all or part of the meniscus is associated with an increased risk of developing knee osteoarthritis.2 The risk of osteoarthritis and its progression increase in line with reductions in tibial cartilage coverage.
Meniscal tears are categorised as traumatic or non-traumatic (degenerative) on the basis of their presentation. Traumatic tears tend to occur in younger active people (<40 years) and are caused by a serious traumatic injury, often while playing sport. Degenerative tears are typically seen in middle aged or older people and often accompany knee osteoarthritis; the prevalence of meniscal damage increases as joint space narrowing becomes more severe.3 4 The medial meniscus is the most commonly torn, and multiple tears are present in more than a third of patients.
Who is at risk?
Population based magnetic resonance imaging (MRI) studies report a 35% prevalence of degenerative meniscal tears in people over 50 years,3 and a 24% prevalence in those with no radiographic evidence of osteoarthritis.5 Most meniscal tears are asymptomatic and prevalence is similar in those with and without knee pain (20% v 25%).5 Although some studies have found that body mass index (BMI) does not affect prevalence,5 others have reported a significantly greater prevalence and severity of meniscal lesions in overweight and obese people compared with those with a normal BMI.6
A cohort study found that knee trauma sufficient to reduce walking ability for at least two days was associated with a fourfold increased risk of developing medial meniscal disease.7 Generalised osteoarthritis and varus alignment were also independent predictors, whereas obesity was a risk factor for meniscal extrusion but not for meniscal lesions.
A systematic review of 11 cohort and case-control studies found that age over 60 years, male sex, work related kneeling or squatting, and climbing stairs were all associated with an increased risk of developing meniscal pathology. It also found moderate evidence that BMI greater than 25 confers an increased risk.8
How does it present?
There is no consensus on what defines a symptomatic meniscal tear, underscoring the difficulty in distinguishing symptoms of knee pain caused by a degenerative meniscal tear from those of underlying osteoarthritis. Degenerative meniscal tears often arise spontaneously or from trivial trauma. New onset of knee pain, accompanied by a locking or catching sensation in the knee (acute block to knee extension), and medial or lateral joint line pain are suggestive of a symptomatic meniscal tear but are non-specific. There may also be swelling, clicking, popping, buckling, or giving way, although giving way is common in middle aged and older people without knee disease.9
Many physical tests—including the McMurray, Apley grind, bounce home, and Thessaly tests—as well as the presence of medial or lateral joint line tenderness and loss of full extension have been purported to be useful in making a diagnosis of a symptomatic meniscal tear, but they have limited diagnostic accuracy.10 Even orthopaedic surgeons can accurately predict an unstable (3 mm full or partial thickness; longitudinal and displaceable; radial, oblique, or complex) meniscal tear using clinical evaluation in only 60% of patients with established osteoarthritis aged 40-70 years.11
A recently developed meniscal symptom index, with a checklist of four symptoms (localised pain, clicking, catching, and giving way), attempts to distinguish between meniscal tears as the cause of symptoms and other sources of knee pain.12 The study looked at 300 participants, 131 of whom were thought to have symptoms relating to a meniscal tear on the basis of orthopaedic diagnostic impression and presence of a tear on MRI. It found that 76% (95% confidence interval 63% to 88%) of those with all four index symptoms had a symptomatic meniscal tear, compared with 16% (2% to 30%) of those with none of the four symptoms. These findings must be interpreted with caution owing to the potentially biased case ascertainment of a symptomatic meniscal tear.
When is imaging indicated?
In middle aged and older people with knee pain, weight bearing plain radiographs may help determine the presence and severity of osteoarthritis and exclude other causes of knee pain, such as osteonecrosis of the femoral condyle or tibial plateau. In patients with any suspected serious causes of disease (for example, history of cancer, systemic features such as fever or soft tissue masses), plain radiographs may also be warranted.
MRI has high sensitivity and specificity for detecting meniscal tears in older patients,13 and ultrasound imaging is almost as good.14 However, as with clinical evaluation, the ability of imaging to discriminate between symptomatic and incidental degenerative meniscal tears in middle aged and older people, with and without osteoarthritis, is questionable.4 5 15 MRI detects meniscal tears in more than 90% of people with moderate to severe osteoarthritis,4 15 but pain and function are similar among those with and without a tear.4
In view of the high prevalence of meniscal tears and their poor correlation with symptoms, indiscriminate use of MRI of the knee in people aged 40 years or more poses a serious risk of overtreatment and potential for harm. In primary care, indications for MRI include a locked knee (a block to extension), where meniscal entrapment is suspected, or as second line imaging when clinical suspicion of a serious cause exists and plain films fail to identify the cause.
What are the treatment options and how effective are they?
Because degenerative meniscal tears are part of the same disease process as osteoarthritis, the treatment approach is similar, although recent evidence throws some previously “standard” practices into doubt. Standard non-operative treatment options have included simple analgesia, non-steroidal anti-inflammatory drugs, glucocorticoid injections, supervised exercise and physical therapy programmes, general advice to avoid trauma and specific movements that aggravate the symptoms, and encouragement of weight loss for overweight or obese people. Previous standard operative treatment options for degenerative tears presumed to be symptomatic have included arthroscopic partial meniscectomy or debridement, with joint replacement reserved for those with severe knee osteoarthritis.
Until recently, few of these treatments had been evaluated in randomised controlled trials. No controlled trials have compared the efficacy of supervised exercise or physical therapy with placebo or watchful waiting. However, one open trial of 102 participants with medial knee pain, mechanical symptoms, and medial meniscal tear reported no differences in pain or function over two years after a strengthening exercise programme compared with partial medial meniscectomy.16 A single placebo controlled trial with 62 participants reported some benefit from low level laser therapy in people with minor (tiny or intra-substance) meniscal tears.17 In addition, a single open trial with 114 participants reported greater symptom improvement with arthroscopic debridement than with intra-articular glucocorticoid injection at one month, although this was not sustained at one year.18
Five other controlled trials have been unable to show a clear benefit of surgery over placebo surgery or non-operative treatment.19 20 21 22 23 In a placebo controlled trial of arthroscopic surgery in 180 participants with knee osteoarthritis, most of whom (172/180) had mechanical symptoms, arthroscopic debridement or lavage showed no advantage over placebo.19 A prespecified subgroup analysis of a second open randomised trial found no significant additional benefit of arthroscopic lavage and debridement over optimal physical and medical therapy for knee osteoarthritis, and no between group differences in outcome among participants with mechanical symptoms (locking or catching).22
An open trial (90 participants with knee pain, medial meniscal tear, and no or minimal osteoarthritis) reported no additional benefit for partial medial meniscectomy over supervised exercise alone.20 In a second large multicentre open trial of 351 participants with knee pain and at least one symptom suggestive of a meniscal tear, arthroscopic partial meniscectomy provided no additional benefit over a standardised physical therapy programme.21 However about a third of participants randomised to conservative treatment in both trials received partial meniscectomy during follow-up. Finally, a randomised placebo controlled trial of 146 participants with knee pain, meniscal tear, and no osteoarthritis, who were unresponsive to appropriate conservative treatment, found no additional benefit of partial medial meniscectomy over arthroscopic lavage alone up to 12 months afterwards.23
What should be first line treatment?
Clinical guidelines for management of knee osteoarthritis consistently recommend individualised treatment plans that may include education (box), self management, exercise, weight loss if overweight, walking aids as indicated, and thermal modalities, as well as paracetamol, non-steroidal anti-inflammatory drugs, and intra-articular glucocorticoids.24
What should be second line treatment?
For refractory symptoms, stronger analgesia may be needed. Because of conflicting or inconsistent evidence, guidelines vary in their support for treatments such as acupuncture, knee braces, heel wedges, intra-articular hyaluronic acid preparations, tai chi, glucosamine, chondroitin, and transcutaneous electrical nerve stimulation.24 There is currently insufficient evidence for platelet-rich plasma or stem cell injections.
The American Academy of Orthopaedic Surgeons and Osteoarthritis Research Society International strongly recommend against lavage and debridement for knee osteoarthritis because of consistent evidence of ineffectiveness.25 26 The 2014 National Institute for Health and Care Excellence guidelines also do not recommend arthroscopic lavage and debridement unless there is a clear history of mechanical locking.27 Although no guideline has explicitly considered degenerative meniscal tears, evidence from randomised controlled trials does not support a role for arthroscopic meniscectomy.
What if non-operative interventions fail?
Joint replacement surgery is recommended for patients with symptomatic osteoarthritis not controlled by non-operative means, regardless of the condition of the meniscus.24 In general it takes many years before symptoms progress to this point. A recent longitudinal study of people with knee osteoarthritis found that those who underwent total knee replacement had radiographic progression and substantial worsening pain and function in the two years before surgery, whereas pain and function remained fairly stable in the non-surgical control group with similar radiographic disease.28
Although evidence from randomised trials for non-operative treatments for degenerative meniscal tears is lacking, it is reasonable to follow clinical practice guidelines for knee osteoarthritis. High quality evidence from multiple randomised trials indicates that arthroscopic meniscectomy is no more effective than placebo or non-operative alternatives for most patients with degenerative meniscal tears. Whether it has a role in those in whom conservative treatment is unsuccessful or for selected subgroups is currently unknown.
How should we advise patients?
Tears of the menisci (often referred to as cartilages) in the knee are common and occur with normal ageing; these are called degenerative meniscal tears and more than a third of people over the age of 50 will have one
Most degenerative meniscal tears don’t cause symptoms and are just as likely to be present in people with and without knee pain
Knee pain in most people is due to osteoarthritis; the pain may fluctuate and resolve with time
Arthroscopic surgery to excise a torn piece of a degenerative meniscus or to remove damaged tissue in the knee is not more effective than placebo (pretend) surgery or exercise therapy
Encourage people with knee pain to remain active and exercise regularly, and to adjust their activities and analgesia according to their symptoms
Weight loss in people who are overweight or obese may reduce pain and slow the progress of the osteoarthritis
Unless a person is suddenly unable to extend his or her knee, a serious cause of pain is suspected, or a knee joint replacement is needed, magnetic resonance imaging is usually unhelpful in patients with knee pain and it can lead to unnecessary treatment
Assessment of the accuracy of diagnostic tools and classification systems in distinguishing symptoms caused by a degenerative meniscal tear from those due to other structures or processes (such as knee osteoarthritis)
Randomised placebo controlled trials evaluating the effectiveness of non-operative treatments (including physical therapy and exercise programmes, injection and oral drugs) for patients with knee symptoms compatible with knee osteoarthritis and potentially a degenerative meniscal tear
Randomised placebo controlled trials evaluating the effectiveness of arthroscopic partial meniscectomy for selected subgroups of people who may have been inadequately represented in previous trials. These might include people with discrete, unstable tears that result in locking of the knee or those with recurring symptoms despite a standardised physical therapy and exercise programme
Studies to identify effective techniques for more rapidly changing practice in response to important new evidence
Cite this as: BMJ 2015;350:h2212
This paper is dedicated to the memory of Andy Sprowson who died tragically on 13 March 2015. He was an academic orthopaedic surgeon who was dedicated to improving evidence based care in his field. He was an exceptionally enthusiastic, bubbly character, who loved to work hard and make new and exciting things happen. He will be sadly missed by both his academic and clinical colleagues.
Contributors: All three authors jointly wrote the article and are responsible for the overall content as guarantors.
Funding: RB is funded by an Australian National Health and Medical Research Council (NHMRC) senior principal research fellowship.
Competing interests: We have read and understood BMJ policy on declaration of interests and we have no interests to declare.
Provenance and peer review: Commissioned; externally peer reviewed.