TRAUMATIC MENISCAL TEARS
FOOTBALLER'S CARTILAGE
Anatomy
There are two menisci in each knee. The medial (inner) and lateral (outer) meniscus are located between the thigh (femur) and shin bones (tibia), are ‘C’ shaped when viewed from above but wedge shaped in cross section. In the first decade of life, the whole meniscus has a blood supply but as the menisci mature the blood supply recedes and is limited to the outer third. The nerve supply to the meniscus follows the blood supply and may provide information to the nervous system regarding knee joint position (proprioception).
50-70% of load placed on the knee is transmitted away from the joint cartilage by the menisci. This protects the cartilage from excessive pressures but is dependent on the menisci, and their attachments to the bones, being intact. The menisci also nourish the joint cartilage, lubricate the joint and provide stability to the knee. The medial meniscus is particularly important for knee joint stability in anterior cruciate ligament injured knees.
Causes
Meniscal tears can be categorised as traumatic or degenerative. It is important to differentiate these two separate presentations to ensure appropriate treatment is provided. Recent evidence suggests that traumatic meniscal tears may already have a degree of meniscal degeneration, implying a potential overlap between the two categories.
Traumatic meniscus tears are caused by a significant, memorable injury to the knee; this typically occurs whilst twisting on one leg with the knee slightly bent. The force exerted on the knee causes a tear in the meniscus, either in isolation or in combination with injury to other knee structures (e.g. anterior cruciate ligament).
Sports such as football and rugby are a risk factor for developing a traumatic meniscus tear, most likely due to the increased frequency of pivoting and twisting movements that are involved with these activities.
Presentation
Traumatic meniscal tears occur most often in younger individuals, especially those aged 20-29. An individual may report some or all of the following history elements; however, patients that have injured their knee without tearing their meniscus may also report a similar history.
- knee pain
- feeling/hearing a sensation/noise (e.g., pop, crack, snap)
- knee giving way/moving out and back in at the time of injury
- inability to continue the activity
- difficulty weight bearing
- rapid onset of knee joint swelling
- difficulty fully straightening the knee
- lack of trust in the knee and/or knee instability.
Diagnosis
Various tests are used clinically in an attempt to diagnose meniscal tears, including joint line tenderness, McMurray’s test and the Thessaly test. However, the diagnostic accuracy of these individual tests for meniscus tears is poor. It is generally recommended that several different positive tests, in combination with the clinical history and exclusion of other diagnoses, are needed to diagnose a traumatic meniscal tear.
Imaging
Magnetic resonance imaging (MRI) has high diagnostic accuracy for identifying traumatic meniscal tears, but the presence of a tear does not confirm that the tear is the source of an individual’s symptoms. Vertical tears that occur in a longitudinal direction (longitudinal tears) typically occur in the periphery of the meniscus and therefore have potential to cause pain, but also to heal. Vertical tears that start from the inner edge of the meniscus and extend across the radius (radial tears) or in an oblique direction (oblique or parrot beak tears) are less likely to cause pain, but may not heal.
Large meniscal tears can cause a physical block to movement, which may require urgent treatment. If the central portion of a longitudinal tear becomes displaced, the tear is called a bucket handle tear, while a displaced oblique tear is described as a flap tear. MRI diagnosis of a meniscal tear is therefore not required unless the knee is locked, as the results of the scan do not influence treatment.
Treatment
Patients presenting with a locked knee (physical block to extension) caused by displaced meniscal tissue are considered appropriate for surgical intervention, and this is often performed on an emergency basis. The physical block is usually a bucket handle tear of the meniscus, but may be caused by other injuries including a rupture of the anterior cruciate ligament or tibial eminence fracture; it is therefore important to differentiate these different injuries.
During surgery, the torn meniscus is either repaired or removed (arthroscopic partial meniscectomy), depending on the location of the tear, direction of the tear (e.g. longitudinal or radial) and whether the tear can be securely repositioned. Meniscus repair provides better long-term results for knee function and X-ray evidence of knee osteoarthritis when compared with partial meniscectomy, but the decision to attempt repair can only be made during surgery. Meniscal repair is performed in approximately one quarter of young patients and has a failure rate of 22-24% within 5 years of surgery. Re-operation rates are lower in lateral meniscal repairs, or if a torn anterior cruciate ligament is reconstructed at the same time as meniscal repair, but are still substantially higher than partial meniscectomy.
The optimal management of traumatic meniscal tears (in patients without a locked knee) is not clear. Earlier studies show that meniscal tears can heal without surgery but those that have not healed may not cause symptoms. In active adults (aged 18-40) with meniscal tears, early meniscal surgery has not been shown to be superior to exercise and education at 12 months. In this study, approximately 75% of patients did not require surgical intervention.
Post-operative rehabilitation
Restricted weight bearing or range of motion (ROM) does not improve outcomes following isolated meniscus surgery (repair or partial meniscectomy). However, any restrictions associated with other procedures performed at the time of meniscus surgery should be considered during post-operative rehabilitation.
Rehabilitation should be progressed based on the impairments present, the individual’s specific requirements (e.g. running, jumping) and their response to treatment. The Knee Resource post-operative protocols are based on published literature for vertical meniscal tears.
Signposting
Individuals with a physical block to knee extension (locked knee) should be referred to an orthopaedic department as soon as possible. Individuals with a suspected traumatic meniscal tear without a locked knee should be assessed and managed by a physiotherapist. If symptoms do not improve, onward referral to orthopaedics is recommended for further assessment.
Written by: Richard Norris
Peer reviewed by:
Prof. Jonas Bloch Thorlund, PhD | @jbthorlund
References
Décary S, Fallaha M, Frémont P, Martel-Pelletier J, Pelletier JP, Feldman D, et al. Diagnostic validity of combining history elements and physical examination tests for traumatic and degenerative symptomatic meniscal tears. PM R. 2017.
Décary S, Ouellet P, Vendittoli PA, Roy JS, Desmeules F. Diagnostic validity of physical examination tests for common knee disorders: An overview of systematic reviews and meta-analysis. Phys Ther Sport. 2017;23:143-55.
O’Donnell K, Freedman KB, Tjoumakaris FP. Rehabilitation Protocols After Isolated Meniscal Repair: A Systematic Review. Am J Sports Med. 2017;45(7):1687-97.
Olsson O, Isacsson A, Englund M, Frobell RB. Epidemiology of intra- and peri-articular structural injuries in traumatic knee joint hemarthrosis – data from 1145 consecutive knees with subacute MRI. Osteoarthritis Cartilage. 2016;24(11):1890-7.
Paxton ES, Stock MV, Brophy RH. Meniscal repair versus partial meniscectomy: a systematic review comparing reoperation rates and clinical outcomes. Arthroscopy. 2011;27(9):1275-88.
Sarimo J, Rantanen J, Heikkilä J, Helttula I, Hiltunen A, Orava S. Acute traumatic hemarthrosis of the knee. Is routine arthroscopic examination necessary? A study of 320 consecutive patients. Scand J Surg. 2002;91(4):361-4.
Skou ST, Lind M, Hölmich P, Jensen HP, Jensen C, Afzal M, et al. Study protocol for a randomised controlled trial of meniscal surgery compared with exercise and patient education for treatment of meniscal tears in young adults. BMJ Open. 2017;7(8):e017436.
Skou ST, Thorlund JB. A 12-week supervised exercise therapy program for young adults with a meniscal tear: Program development and feasibility study. Journal of Bodywork and Movement Therapies. 2017 Jul 27.
Stein T, Mehling AP, Welsch F, von Eisenhart-Rothe R, Jäger A. Long-term outcome after arthroscopic meniscal repair versus arthroscopic partial meniscectomy for traumatic meniscal tears. Am J Sports Med. 2010;38(8):1542-8.
Thorlund JB, Englund M, Christensen R, Nissen N, Pihl K, Jørgensen U, et al. Patient reported outcomes in patients undergoing arthroscopic partial meniscectomy for traumatic or degenerative meniscal tears: comparative prospective cohort study. BMJ. 2017;356:j356.
Weiss CB, Lundberg M, Hamberg P, DeHaven KE, Gillquist J. Non-operative treatment of meniscal tears. J Bone Joint Surg Am. 1989;71(6):811-22.
Wesdorp MA, Eijgenraam SM, Meuffels DE, Bierma-Zeinstra SMA, Kleinrensink GJ, Bastiaansen-Jenniskens YM, et al. Traumatic Meniscal Tears Are Associated With Meniscal Degeneration. Am J Sports Med. 2020;48(10):2345-52.