Treatment of Meniscal Tears
Treatment of Meniscal Tears
Meniscal Surgery

Knee Arthroscopy
  • Knee arthroscopy is key hole surgery to the knee
  • A torn meniscus that causes locking and inability to get knee fully straight requires an urgent MRI scan, followed by an urgent knee arthroscopy
  • The longer this is left untreated the less likely the torn meniscal tissue will be reducible and in a state that would be amenable for repair, thus increasing the risk of needing a large section of the meniscus to be removed
  • Knee arthroscopy can be considered for non-urgent meniscal tears that symptoms persist despite a course of conservative management
  • It involves two small cuts on either side of the patella tendon, putting a camera in and looking all around the knee joint
  • With the aid of a probe the menisci, articular cartilage and cruciate ligaments are assessed.
  • Meniscal tears are either:
    • trimmed to a stable base (called partial meniscectomy) so as to prevent propagation of the tear whilst trying to preserve as much meniscus as possible or
    • repaired
What does an arthroscopic partial meniscectomy involve?
  • Arthroscopic partial meniscectomy involves the arthroscopic removal of the torn section of the meniscus (not the whole meniscus) and smoothening of the remaining meniscal surface so as to prevent further tearing of the meniscus
  • Arthroscopic partial meniscectomy is the most common orthopaedic procedure performed as a day case:
    • In other words the patient is able to go home the same day that they have the operation

How is an arthroscopic partial meniscectomy carried out?
  • The camera is inserted into the knee through one of the portals on the side of the patella
  • Arthroscopic instruments are then inserted through the portal on the other side of the patella
  • Under direct vision the torn section of the meniscus is trimmed using arthroscopic long slender instruments that cut and bite off the torn meniscus
  • An arthroscopic shaver is then commonly inserted which has a reciprocating blade and with the aid of suction is able to pull and trim soft tissue and the remaining meniscal surface is smoothened out

Why carry out an arthroscopic partial meniscectomy?
  • The torn piece of meniscus is caught and pulled during knee movement between the femur and tibia causing a sharp pain
  • Therefore removing the torn part of the meniscus alleviates the pain 
  • This can be likened to a torn finger nail which keeps getting caught in surfaces such as clothes:
    • It is this catching of the fingernail which is painful and by trimming it back and filing down the finger nail to a smooth surface that it's no longer painful when the fingernails are rubbed on a surface
  • Arthroscopic partial meniscectomy is suitable when suturing of the torn meniscus is not feasible or will not yield good results
  • The torn part of the meniscus is no longer functional and so does not offer any protection to the articular cartilage
  • However, removal of the torn section of the meniscus prevents further propagation of the tear which then defunctions a greater section of the meniscus:
    • This can be likened to trimming a tear in a fabric so as to prevent the tear from elongating and spreading
  • Essentially, partial meniscectomy limits the enlargement of the meniscal tear so that a larger part of the meniscus is not injured and subsequently removed

When is an arthroscopic partial meniscectomy indicated?
  • Arthroscopic partial meniscectomy is suitable for:
    • Meniscal tears that are not repairable such as in degenerate tears
    • Meniscal tears that are located centrally in the white zone where there is no blood supply 
    • Meniscal tears in the elderly due to further reduced blood supply
    • Meniscal tears that cause locking to knee motion
    • Meniscal tears that block the ability to get the knee fully straight
    • Meniscal tears that continue to be symptomatic after a trial of conservative treatment (typically three months)
    • Meniscal tears that cause symptoms which make activities of daily living difficult

What are the consequences of a partial meniscectomy?
  • Meniscal injury and subsequent partial meniscectomy leads to 7 times greater risk of developing subsequent osteoarthritis:
    • This risk is dependent on the location and extent of the meniscal tear, how much meniscus is removed and the state of the remaining meniscus
    • The reason for the increased risk of osteoarthritis following removal of some of the meniscus is due to the loss of shock absorption and protection the meniscus offers to the articular cartilage
  • Clinical long term outcomes of partial lateral (outer) meniscectomy are worse than those following partial medial (inner) meniscectomy
  • About 95% of patients following a partial medial meniscectomy have good to excellent results
  • This drops to 77% for partial lateral meniscectomies
  • Loss of the medial meniscus leads to reduction of contact area by 75% and increase in peak contact pressures by around 235%
  • This leads to more rapid damage of the articular cartilage and earlier onset of osteoarthritis
  • Forces in the knee increase by 98% and 177% following partial and total medial meniscectomy, respectively
  • Forces in the knee increase by 288% and 323% following partial and total lateral meniscectomy, respectively
  • Partial meniscectomy increases the risk of arthritis 4 times at 16 years after surgery
  • Total meniscectomy increases the risk of arthritis 14 times at 21 years after surgery
  • Hence the need to see a knee specialist who will be able to repair a meniscal tear wherever possible especially on the lateral side


What is an arthroscopic meniscal repair?
  • Arthroscopic meniscal repair involves suturing together the torn meniscus in order for the torn ends to heal back together and therefore restore its structure and function
  • There are different suturing techniques as discussed below but they all involve placing sutures across the tear in order for the tear to heal
  • This is different to arthroscopic partial meniscectomy whereby the torn section of the meniscus is removed
  • It is always preferential to save the meniscus in order to preserve its protective properties to the articular cartilage and the stability it provides to the knee

How soon should an arthroscopic meniscal repair be carried out?
  • Generally speaking arthroscopic meniscal repair does not need to be carried out urgently
  • However it should be carried out as soon as possible and within two months by an orthopaedic surgeon specialising in knee sports injuries 
  • Leaving it longer reduces the chances of a successful repair because the torn sections can be further damaged making repair more difficult and perhaps not possible
  • The blood supply to the torn sections is also affected which reduces the healing potential
  • The only meniscal tears that need to be treated urgently are those that cause locking of the knee whereby knee motion is blocked and cannot flex (bend) or extend (straighten)

Why should an arthroscopic meniscal repair be carried out?
  • The purpose of an arthroscopic meniscal repair is to  save the meniscus
  • The meniscus is a key structure within the knee and provides numerous important functions without which the longevity and function of the knee are compromised
  • The principal functions of a meniscus are:
    • Shock absorber:
      • The meniscus acts to absorb shocks within the knee and therefore protect the articular cartilage from damage
    • Distribute load:
      • The menisci occupy around 60% of the contact area between the tibia and the femur
      • When standing the menisci transmit over 50% of the load
      • When the knees are flexed (bent) to 90 degreed this increases to ~90% all of which goes through the posterior (rear) part of the meniscus 
      • This is why the posterior (rear) part of the meniscus is more likely to be injured
    • Increase stability between femur and tibia:
      • The menisci are wedge shaped and go around the femoral condyles 
      • Menisci provide stability to the knee joint by reducing the front to back as well as rotational forces of the femur in relation to the tibia
      • The stability the menisci provide on the femur can be likened to triangle wedges (in this case the menisci) being placed around a wheel (in this case the femoral condyle) of a car or an airplane to stabilise it when parking
    • Aid lubrication of the knee joint:
      • In all normal knee there is a natural lubricant (synovial fluid) which reduces friction during knee motion
      • The meniscus acts like a windshield wiper spreading the lubricant fluid over the articular cartilage
    • Aid nutrition of the knee joint:
      • Articular cartilage obtains nutrients and gets rid of waste via diffusion and not by direct blood supply
      • As a result movement of fluid on its surface is key to ensuring healthy function of the cartilage
      • The meniscus with its windshield wiper effect aids in the movement of fluid on the surface of articular cartilage
  • It is therefore clearly evident that saving the meniscus by repairing it is preferable to removing it 

What are the indications for arthroscopic meniscal repair?
  • The indications for repairing a meniscal tear are:
    • Young patients <40 years:
      • The blood supply and healing potential of a meniscal tear reduce with age
      • The younger the patient the greater the need to repair the meniscal tear due to the consequences of losing part of the meniscus
    • The presence of an ACL tear:
      • It has been shown that repairing a meniscal tear in the presence of an ACL reconstruction improves the healing potential of the meniscal repair 
      • This is due to the ACL reconstruction providing a more stable knee which is required for the meniscus to heal as well as an increase in various substances such as growth factors which are released whilst drilling the bones during the ACL reconstruction
      • If a meniscal repair is carried out in the presence of an ACL tear which is not reconstructed at the same time there is a high chance of the repair failing due to the ongoing instability of the knee 
    • Simple meniscal tear pattern:
      • Suturing together two pieces of torn meniscus can be achieved 
      • When the torn meniscus has disintegrated into numerous planes and pieces then there is little to no hope of achieving a successful repair
    • Location of tears that are more important to try and repair:
      • Meniscal root tears:
        • Meniscal root tears are the most serious type of meniscal tear
        • Each meniscus is anchored on the tibia by two roots located centrally in the knee very close to the cruciate ligaments
        • Losing a root defunctions the whole meniscus completely and essentially renders it useless as if the whole meniscus has been removed
      • Meniscal radial tears:
        • A meniscal radial tear is one that extends from the central portion of the meniscus (white zone) all the way to the periphery (red zone)
        • The radial tear essentially disrupts the circumferential collagen (protein) fibres which manage to hold the meniscus together when they are compressed and so it loses its shock absorbing capability
      • Meniscal bucket handle tears:
        • Meniscal bucket handle tears are longitudinal tears (i.e. run the length of the meniscus) and when they displace they can cause locking and block the ability to straighten the knee
        • They need to be surgically reduced and repaired whenever possible so as to regain knee motion whilst also saving the meniscus
  • Unfortunately not all meniscal tears can be repaired
  • The blood supply to the meniscus comes from the periphery (red zone):
    • Meniscal tears in the periphery have good healing potential and so are repairable
  • The central part of the meniscus (white zone) does not have its own blood supply:
    • Central meniscal tears do not have good healing potential and so are not repairable and are trimmed to a stable base (meniscectomy)
  • Unfortunately due to the meniscus's poor blood supply, it has low healing potential and this means that even with a fresh tear, meniscal repair in the elderly does not have great healing potential 
  • However, there is increasing evidence that under ideal conditions meniscal repair in 60+ year olds have good results

What are the different techniques used to repair meniscal tears?
  • The purpose of a meniscal repair is to suture together the torn sections and then to provide an environment to give time for the sections to heal together
  • The different techniques used to repair meniscal tears:
    • All inside: 
      • A hand-held device is inserted into the knee through one of the portals and the sutures and knots are made inside the knee
    • Inside-out: 
      • The sutures pass from inside the knee and come out through the skin
      • This is commonly used by specialist knee surgeons to repair more complex meniscal tears
    • Outside-in: 
      • This involves passing sutures from outside the skin into the meniscus
      • Commonly done for anterior meniscal tears (tears located towards the front of the knee)
    • Open: 
      • This is when an incision is made on the knee to approach the meniscus, visualise it directly, and repair it
  • Root repair:
    • This is a technically challenging procedure and should be done by a knee specialist
    • The aim is to anchor the meniscus back down to where it should be
    • Each meniscus is anchored on the tibia via two anchors (a front and a back one) located towards the centre of the knee very close to the cruciate ligaments
    • The detached root of the meniscus is sutured
    • A drill hole is made at the front of the tibia going upwards and backwards inside the knee joint at the location of where the meniscal root normally anchors into the tibia
    • The sutures are then brought down the drill hole and secured at the front of the tibia

What is recovery like following meniscal surgery?
  • It is important in the first two weeks following meniscal surgery to reduce knee swelling which will in turn reduce pain, stiffness and expedite recovery
  • Rest:
    • This helps to reduce strain on the knee and subsequent swelling
  • Ice:
    • Frequent icing of the knee helps to reduce inflammation and swelling inside the knee
  • Compression with an elastic bandage:
    • Wrapping the knee up with an elastic bandage will help reduce knee swelling
  • Elevation:
    • Elevating the leg will help reduce knee swelling with the help of gravity

What is recovery like following arthroscopic partial meniscectomy?
  • Following arthroscopic partial meniscectomy the patient can walk fully weight bearing on the operated leg from the first day with the aid of crutches for balance purposes but without a knee brace
  • Full recovery is made typically within 3-4 weeks

What is recovery like following arthroscopic meniscal repair?
  • Recovery following arthroscopic meniscal repair is slower than following meniscectomy because the repair needs to be protected for a period of time whilst it heals
  • Following arthroscopic meniscal repair the patient can walk fully weight bearing on the operated leg from the first day with the aid of crutches for balance purposes but with a knee brace worn continuously for 6 weeks
  • Knee flexion (bend) is limited to 90 degreed for the first 6 weeks and after that full range of motion is regained
  • Squatting beyond 90 degrees of knee flexion (bend) is allowed after 3 months
  • Walking without a knee brace commences at 6 weeks
  • Full recovery is made typically within 3-6 months

How to prevent a meniscal tear?
  • Most meniscal tears in the young are due to trauma and so are hard to prevent
  • Most meniscal tears in the elderly are due to degeneration from wear and tear and are also hard to prevent
  • However, there are things that can be done to reduce the risk of a meniscal tear
  • Keeping a healthy diet as well as regular exercise will help avoid being overweight which in turn increases the forces and wear and tear on the knees
  • Avoiding deep squats and kneeling helps reduce the stresses on the knees and in particular the posterior (back) portion of the meniscus which is the most commonly torn site:
    • When the knee flexes (bends) the posterior (back) portion of the meniscus takes most (90%) of the load on the knee between the femur and the tibia
  • Not all exercises carry the same risks to injury
  • Exercises that are gentle on the knees and menisci are straight line and low impact activities:
    • Exercise bike
    • Elliptical trainer
    • Rowing machine
    • Pilates
    • Floor exercises
    • Strength training
  • Exercises that are high impact activities can produce loads which are multiple times the body weight and these increase the risk of injuries to the knee including to the meniscus
  • Low impact activities have resistance throughout the cycle of motion whereas high impact occurs when the foot comes off the ground and then comes back down
  • Walking is the gentlest of high impact activities since it produces forces to the knees which are 1.5 to 3 times the body weight 
  • Jogging, running and sprinting increase the impact to the knee the faster you run which can reach 5, 10 and in elite athletes 20 times the body weight
  • High impact activities are therefore all sports that include running
  • When high impact activities are then combined with rapid change of direction and physical contact then the risk of injury increases further such as in:
    • Basketball
    • Football
    • Volleyball
    • Handball
  • To carry out sports and activities that carry a higher risk of injury then it is advised to be in better physical conditioning before carrying out these sports as well as being assess by an orthopaedic specialist in sports injuries to see what deficits exist and how to improve them
  • The key points to improve are:
    • Strength:
      • This should be whole body strength
      • Symmetrical for both agonist and antagonist muscles
      • Focusing on compound movements and less on isolated movements
      • Core strength
      • Lower limb strength
    • Endurance:
      • Research has shown that most injuries tend to occur towards then end of a game or of an exercise session when muscles fatigue and they are less able to provide stability around a joint
    • Balance:
      • Having good balance whilst changing direction and whilst landing is key to avoiding lower limb injuries
    • Flexibility:
      • Efficient performance requires joints having a full range of motion
      • This becomes even more important as we get older and the joints become stiffer
      • It is important to warm up gradually and stretch before carrying out intense activity as well as stretch at the end of the exercise session
  • Incorporating an injury prevention programme regularly three times a week for at least three months has been shown to drastically reduce the risk of lower limb injuries
  • Increase the intensity of exercise workouts gradually and never abruptly in order to avoid injury
  • When training a particular section of the body allow 2-3 days of rest to avoid fatigue injuries
  • Ensure appropriate shoe wear are worn for the activity carried out

Meniscal Transplantation Surgery
  • This procedure is indicated when the patient has had a complete or near complete removal of their meniscus (meniscectomy) and they have pain on that side of the knee
  • The procedure involves taking a meniscus allograft from a donor
  • Has best results when there is no arthritis and no other ligament injury
  • Has good results in the presence of some arthritis 
  • The aim of the meniscus transplant is to buy time 
  • Suitable for when there is little to no functioning meniscus remaining following previous complete or subtotal meniscectomy
  • If the leg is not neutrally aligned then an additional realignment operation (osteotomy) is performed so as to better balance the forces going through the knee joint and so protecting long term both the joint surface and the meniscus
  • Without the realignment operation there is a high risk of failure
  • If one side of the joint surface has severe arthritis with exposed bone, additional procedures such as a microfracture or osteochondral allograft can be performed (replacing the damaged area with a donor’s bone and cartilage)
  • If there is a ligament injury such as an ACL tear then this will need to be addressed as well
  • When there is bare bone on both sides of the knee joint surfaces, then the arthritis has progressed too far for a meniscus transplant to be beneficial
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