What is a Meniscus Injury?
The meniscus or knee cartilage lies within the knee joint surfaces. The medial & lateral meniscus are horseshoe-shaped structures composed of fibrocartilage. The meniscus on the inside of the knee is known as the medial meniscus and the lateral meniscus lies on the outer side. The meniscus acts to cushion forces by acting as a shock absorber & by spreading the weight more evenly over the articular cartilage on the surface of the bones. The amount of force transferred through the cartilage increases exponentially as the speed of movement increases. They also aid in lubrication & nutrition of the joint and act to reduce joint friction.
The medial meniscus is more prone to injury than the lateral meniscus. The inner two thirds of the meniscus has no blood supply & therefore it is particularly challenging in terms of healing capacity.
When people talk about having a cartilage injury they are generally referring to a meniscus tear within the knee.
Injury to the meniscus often alters joint kinematics, leading to increase joint stress. This can accelerate degenerative joint surface changes in the knee.
Physiotherapy Treatment for a Meniscus Injury
Physiotherapy interventions are the primary management tool for small meniscal tears and for chronic degenerative meniscus tears that do not impede greatly upon daily function. Management options include physiotherapy interventions for strength, joint control and range of motion allied with activity modification to manage symptoms & inhibit progression. In cases where the shock absorption capacity at the knee has been diminished due to meniscus injury, strength training can decrease the pressure on the joint by providing dynamic stability to the knee joint. Surgical options include a meniscal repair or meniscectomy where part of the meniscus is removed.
As mentioned, the outer third of the meniscus has a blood supply and therefore is much more open to healing than the inner two thirds which has no blood supply. An improvement in symptoms should be expected within twelve weeks or surgery may be indicated. Surgery will normally be performed arthroscopically, meaning by use of a tiny camera to either remove the torn fragment or to repair (stitch) the tear if it is near the periphery. Even in cases where surgery is necessary, a physiotherapy intervention is vital to optimise strength and accelerate recovery post-surgery. Even when a meniscal tear is diagnosed, in the absence of symptoms such as joint locking, giving way or recurring swelling the latest approach is to try to avoid surgical intervention.
The goal of physiotherapy treatment is to:
- Decrease pain & swelling
- Increase range of motion
- Strengthen the affected knee
- Improve strength & control at the hip & trunk
- Improve proprioception & balance of the lower limb
- Prevent further deterioration
Ross discussing knee pain on KFM radio:
Medial Meniscus Injury:
The menisci — the medial and lateral – are crescent-shaped bands of thick, rubbery cartilage attached to the top of the shinbone (tibia). They act as shock absorbers and stabilize the knee.
The medial meniscus is more vulnerable to injury as compared to its lateral counterpart. The lateral meniscus is mobile, whereas the medial meniscus is attached to joint capsule and medial collateral ligament making it more rigid.
A meniscus tear can occur when the knee is suddenly twisted while the foot is planted on the ground. A tear can also develop slowly as the meniscus becomes rigid with age.
A meniscus tear usually occurs in contact sports where sudden twisting action is involved. Severe pain and swelling may occur within 24 hours. Walking becomes difficult. Bending or twisting the knee is painful. There may be locking while bending or straightening the knee if a loose piece of cartilage gets stuck in the joint.
Does the Type of Meniscus Tear Impact on Healing Speed
The type of meniscus tear will impact on healing time. Vertical-longitudinal and bucket handle tears of the meniscus tend to repair more quickly. They are better suited to exercise rehabilitation as they have been shown to heal in response to weight-bearing. In contrast to this, more complex radial & diffuse tears tend to distract when performing weight-bearing exercises. This type of tear requires a slower rehabilitation progression over six months while healing is taking place.
The end phase of healing, at the point of return to sport, the injured limb should be at lease 90% of the strength of the non-injured limb. The circumference of the injured leg should be within 1.5cm of the normal leg. An absence of swelling and normal power output and hopping capacity determines readiness to return to sport.
Is Physiotherapy or Surgery better for a Meniscus Tear?
Katz et al. (2013):
In a large study following 351 people with meniscus tears published in the New England Journal of Medicine it was demonstrated that those suffering from knee arthritis or meniscal tears achieved comparable results from physiotherapy & from surgical intervention. Improvements were compared between the surgery and physiotherapy groups at six and twelve months.
After six months, both groups experienced similar & substantial improvements in pain & function. Only a small number of people chose to undergo surgery from the physiotherapy group. In those in the physiotherapy group who had shown improvement at six months there was a continued improvement in symptoms at the twelve month mark.
Kies et al. (2016):
This study included 140 adults who had knee pain due to a degenerative meniscal tear. The participants were randomly assigned to have either arthroscopic surgery followed by daily exercises at home to reduce swelling and regain motion or to work with a physiotherapist on neuromuscular and rehabilitation exercises 2-3 times a week for 12 weeks.
Periodic testing for the next two years showed improvement in both groups. Muscle strength had improved more, on average, in the physical therapy group at the three-month checkup, but at the final two-year checkup, there was essentially no difference between the surgery and therapy groups, including in pain, function, and quality of life. The authors reported that 19 percent of the physiotherapy group opted to have surgery at some point but had achieved “no additional benefit” by the end of the study.
Surgery for Meniscus Tear is Not Advised for Middle Aged & Older
Roughly 3 in every 4 patients undergoing arthroscopic knee surgery for meniscus tear, cartilage lesions or knee arthritis are 35 or older. Recent research for basic knee procedures involving a meniscal repair or “cleaning out the knee” has raised some serious questions regarding its effectiveness. The British Medical Journal cites “scandalously poor”evidence supporting the use of common orthopaedic procedures such as knee arthroscopies.
The authors discuss the randomized trials (the top ranking forms of research) investigating the effect of so called ‘clean outs’ or arthroscopic partial meniscectomy to date. They state that “all but 1 of these 9 trials of arthroscopic surgery in middle-aged or older people with persistent knee pain failed to show any added benefit of interventions arthroscopic surgery over a variety of control treatments.”
The original randomised controlled trial analysing the effect of knee arthroscopic surgery showed that a fake placebo surgery produced the same results as real knee surgery (Moseley et al. 2002)
What if My Knee is ‘Locking’ or ‘Catching’. Does this mean I need Surgery?
Despite the extremely poor evidence for surgical procedures to treat knee pain, it is widely believed amongst clinicians that a small subgroup of patients that have catching or locking of the knee are particularly strong candidates for knee surgery. The theory is that when a piece of cartilage becomes loose in the joint that this causes the catching or locking.
If this symptom is backed up by MRI findings then this is deemed to be a very strong indication for knee surgery. As a consequence, surgical removal of this loose body should improve pain or function.
A secondary analysis of the FIDELTY trial comparing knee surgery (partial meniscectomy) with a placebo surgery in the group with catching or locking showed that outcomes were identical between the surgery and placebo group.
What’s fascinating is that one study showed that knee locking is present in about half of knee pain patients who do not have a cartilage tear. It is also present in half of patients who do have a cartilage (meniscus) tear. This suggests that mechanical symptoms in the knee are not a specific symptom of knee cartilage tears.
The Latest Research Suggests the Future Direction of Knee ‘Clear Outs’
The latest paper to address the issue of knee arthroscopy in middle-aged and older patients is entitles, “Routine knee arthroscopic surgery for the painful knee in middle-aged and old patients-time to abandon ship”. The title is a give away of the current state of the research on this topic.
Some individuals are under the misconception that having surgery will decrease the risk of arthritis. The research shows that the opposite is in fact true and that your risk of needing a knee replacement increases if you have surgery to remove a torn piece of cartilage.
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Katz et al. (2013). Surgery versus Physical Therapy for a Meniscal Tear and Osteoarthritis. New England Journal of Medicine. 2013 May 2;368(18):1675-84.
Kise N. et al. (2016). Exercise therapy versus arthroscopic partial meniscectomy for degenerative meniscal tear in middle aged patients: randomised controlled trial with two year follow-up. BMJ 2016;354:i3740.
Thorlund JB, Pihl K, Nissen N, Jørgensen U, Fristed JV, Lohmander LS, Englund M. Conundrum of mechanical knee symptoms: signifying feature of a meniscal tear? Br J Sports Med. 2019 Mar;53(5):299-303. doi: 10.1136/bjsports-2018-099431. Epub 2018 Aug 31. PMID: 30170997. https://pubmed.ncbi.nlm.nih.gov/30170997/
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