KNEE MENISCAL HORIZONTAL CLEAVAGE TEAR
Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies
The two menisci are crucial to the stability of the knee during movement, and to the durability of the knee over time. Tears in a meniscus will decrease the knee’s stability and increase the wear of the articular cartilage. Tears can occur because of degenerative stiffening with aging, or through abnormal isolated or repetitive movements such as due to an acute or chronic ligament tear. Meniscal tears can also occur due to an abnormally shaped or attached meniscus that doesn’t move or distribute forces effectively. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
Meniscal tears can be partially or completely through the meniscus, they can be single or in multiple locations, and they can have complex shapes.
Longitudinal or vertical tears occur in the periphery or substance of the meniscus. They can allow the medial flap of the meniscus to slide into the joint or they can extend and allow the flap to flip into the central part of the knee joint. This is known as a bucket handle tear. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
A flap or oblique tear has a loose medial flap, and can occur as an acute tear, or as a progression of a longitudinal tear. They can also flip into the knee joint.
Vertical tears can also be radial or transverse, or have loose tags.
Horizontal or cleavage tears usually occur in the degenerate stiff meniscus.
Tears may be asymptomatic, or they may cause locking, catching, giving way, pain or swelling. The outer third of the meniscus has a blood supply, so tears in this region may heal. Tears in the inner two thirds of the meniscus don’t heal, and are likely to become longer and cause worse symptoms. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
Over time, meniscal tears can lead to indentation of the articular surface, with fissures and erosions of the articular cartilage. This can lead to accelerated cartilage degeneration and osteo-arthritis, especially if there are also abnormal movements due to loose or torn ligaments. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
During movements of the knee, the menisci can be injured if they fail to follow the movements of the femoral condyles on the tibial condyles. They are 'caught unawares' in an abnormal position and are squashed. This can happen during violent extension of the knee, such as when kicking a ball. If one of the menisci fails to move forwards, it can be caught between the femoral and tibial condyles as the tibia is forcefully applied to the femur. This mechanism leads to transverse tears or detachment of the anterior horn which then becomes folded on itself. The other mechanism producing lesions of the menisci involves a twisting movement of the knee joint, which combines with lateral displacement and lateral rotation. The medial meniscus is then pulled towards the centre of the joint under the convexity of the medial femoral condyle. When the joint is extended, the meniscus can be crushed between the two condyles, leading to longitudinal splitting of the meniscus, a complete detachment of the meniscus from the capsule, or a complex tear of the meniscus. In all these longitudinal lesions, the central part of the meniscus can rear itself up into the intercondylar notch so that the meniscus assumes the shape of a bucket-handle. This type of lesion is very common among footballers (ie during falls on a flexed leg) and among miners who have to work crouched in narrow seams of coal. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
As soon as a meniscus is torn, the injured part fails to follow the normal movements and becomes wedged between the femoral and tibial condyles. The knee as a result 'locks' in a position of flexion, which is more marked the more posterior the rupture. Full extension is then impossible.
It is unusual to see a true, fresh, isolated avulsion of a meniscus caused by a single traumatic episode. Usually this type of injury is associated with acute ligamentous disruption. Moreover, these traumatic disruptions occur at the periphery, often in the deep capsular fibers rather than in the substance of the cartilage. They are highly vascular and suitable for repair. Two elements must be present in most meniscal lesion: first, attrition of the cartilage: and second, trauma to propagate the defect. Menisci become progressively more stiff as their fibro-cartilage matrix changes with the normal processes of aging. As they become stiffer and less resilient, they are more susceptible to tears, which are often referred to as horizontal cleavage tears. Nevertheless, even in the young individual twisting injuries, particularly under compression, cause mid-substance tears of a horizontal, radial (vertical), or longitudinal variety. The medial edges of these tears may dislocate into the joint. These injuries are referred to as bucket handle tears. Alternatively, small tags, from the anterior or posterior horn may ultimately become symptomatic. These injuries are called pedunculated (tag) tears or parrot beak tears. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
The larger, broader, circular lateral meniscus has a higher incidence of tears in the Eurasian population and is more subject to congenital variations, ie the broad discoid meniscus, which fills the lateral half of the joint and interferes with normal movement patterns. Lateral menisci also seem to be more prone to degenerative cysts in their peripheral margins. In some individuals with congenitally lax ligamentous structures, the posterior horns of the menisci are highly mobile. This situation may result from anterior cruciate and capsular laxity secondary to trauma. The menisci may produce a symptomatic snap during flexion of the knee. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
Without the normal meniscus, the knee joint suffers and is susceptible to degenerative changes. The normal meniscus carries 40 to 70% of the load across the knee. After partial menisectomy of bucket handle tears, contact areas decrease approximately 10%, and peak contact stresses increase about 50 to 60%. After total menisectomy, contact areas decrease approximately 75%, and the peak local contact forces increase as much as 235%. Repair of meniscal tears tends to normalize the stress, and the increase in stress with partial menisectomy is proportional to the amount of meniscus removed.
A normal meniscus is the ideal situation. Minor tears that cause few mechanical symptoms and only a small amount of pain on occasion, probably do not damage the joint. The knee is probably better off with a minor tear of a meniscus in situ than without a meniscus. A knee with partial removal of a meniscus lasts longer and does better than a knee that does not have a meniscus. Total meniscectomy is preferable to leaving a large symptomatic tear, with resultant repeated giving way, locking, and effusion. As far as menisectomy is concerned, the younger an individual when a menisectomy is performed, the worse are the eventual changes in the joint. Similarly, in the elderly, removing the torn meniscus from a joint that already has degenerative changes causes rapid advance of any existing osteo-arthritis. Women may have worse results than men, which is related to alignment of the femurs in respect to the width of the pelvis, as well as the generally slightly higher incidence of ligamentous laxity in women. Except for those with significant varus alignment, individuals do worse after a lateral menisectomy than a medial menisectomy. Total removal of the meniscus provides a more rapid onset of degenerative changes than partial removal of the meniscus. Furthermore, those who already have some instability or degenerative changes in the knee do worse after a menisectomy than those without degenerative changes or unstable ligaments. Hence a healthy, normal meniscus is obviously desirable, but in the presence of a severe symptomatic tear, menisectomy is still the treatment of choice. Wherever possible, partial rather than complete menisectomy should be carried out. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
Meniscal pathology is common, yet the clinical diagnosis is often difficult, even for the experienced surgeon. Indeed in some series, the clinical diagnosis of meniscal lesions is accurate in only 40 percent of the cases when not supported by some other investigation. Of the large variety of tests described in the literature, there are three or four well chosen and practiced tests that enhance clinical acumen. There is usually a need for supplementary tests if the knee is not frankly locked. Although there may be no single reliable test for meniscal tears, a combination of symptoms and signs indicate the correct diagnosis most of the time. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
The meniscus itself has little in the way of sensory nerve supply. In fact, it is probably almost devoid of nerves except in its periphery, where it becomes confluent with the synovial lining of the joint. Therefore the symptoms due to a torn meniscus are generally related to mechanical dysfunction causing traction on the periphery of the meniscus, which may produce synovitis, swelling of the synovial lining, or mechanical blocking, as is frequently seen with a bucket-handle or beak tear. Additionally, the symptoms of a meniscal lesion may include the following:
1. swelling proportional to activities
2. pain on rotary or flexion motion, particularly near the extremes of flexion
3. pain on the joint line
4. feeling of weakness and insecurity
5. giving way
7. generalized aching in the knee joint itself
8. popping, catching or grinding.
Repeated popping occurs in approximately 43% of patients with proven meniscal lesions, swelling in 51%, and pain localized to the joint line in 60%.
Effusions. Joint swelling indicates that there is a liklihood of intra-articular pathology, and it is a particularly reliable, if not specific, sign of internal derangement. Detecting a small amount of fluid requires considerable care, and the 'wipe' test is probably most sensitive for this purpose. Ballotment for a floating patella allows assessment of large volumes of fluid. Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies.
Tenderness. Discomfort along the joint line is present in approximately 77% and falsely present in 11% of meniscal lesions. Although not specific for meniscal pathology, it is still the most reliable sign. In the acute situation, excess pressure on the locked knee often refers pain directly to the joint line on the side of the affected meniscus.
Locking. Inability to extend the knee may be caused by a displaced meniscal flap, a loose body, articular surface damage, or a torn anterior cruciate ligament. Pseudo-locking, which may be caused by hamstring spam, is difficult to distinguish clinically. True locking, which occurs at the time of injury, frequently prevents the terminal 20 to 30 degrees of extension, and is a reasonably reliable sign. After a few hours to a few days, even if the knee remains locked, it approaches extension more closely. With the chronic bucket handle tear, 'locking' is usually a subtle sign and constitute a loss of only about 5 degrees of extension. It is best visualized by lifting both of the patient's legs, keeping the malleoli together and viewing along the length of the legs from the end of the examining table. Unlocking of the knee joint in the presence of a chronic tear frequently represents anterior extension of the tear, rather than relocation of the displaced fragment of meniscus.
Manipulative tests attempt to localize the pain to the joint line or to produce clicking secondary to the abnormal mechanics of the torn meniscus.
The McMurray test is positive in about 58% and falsely positive in 5% of normal knees. It is sometimes difficult to discern the 'clunk' of a torn meniscal flap from other 'clicks' in the joint that are secondary to patellar motion or other mechanical phenomena. The McMurray test is a forced internal external rotary motion of the tibia that accompanies flexion and varus-valgus stress. The key to the test is obtaining absolutely full flexion and thus it can not be performed in the presence of a significant effusion. The test may be recorded as negative, positive for joint line pain, or positive for both pain and a clunk. This latter situation is the classic sign. Identical clicks or clunks in both knees do not constitute a positive sign, and there should be reservation in classifying a painless 'clunk' as positive.
Steinmann Test. Starting with the knee flexed to 90 degrees, forced external rotation gives pain on the medial joint line. Conversely internal rotation gives lateral joint line (lateral meniscus) pain. The test is performed at varying positions of knee flexion. This test may be performed in sitting of lying. Furthermore when joint line tenderness moves posteriorly with increasing degrees of flexion, it tends to distinguish meniscal pathology from injury of the capsular ligaments and osteophytes.
Helfet sign. A positive test is dependent on a meniscal lesion mechanically affecting the conjoint lateral rotation of the tibia during extension.
Apley test. The Apley compression and distraction maneuvers are performed with the knee flexed to 90 degrees and the patient prone. Pain only on distraction suggests possible ligamentous involvement. Pain and possible grinding on compression with forced rotation suggests meniscal pathology or articular surface changes.
Anderson test. Another compression maneuver is the mediolateral Anderson grind test. With the knee at 45 degrees, a valgus stress is applied as the knee is simultaneously slightly flexed followed by a varus component while the knee is extended. This maneuver produces a gentle circular motion of the knee. A longitudinal or flap tear tends to give a distinct grinding sensation in the joint line. A complex tear produces more prolonged grinding. A similar sensation may also be present with osteoarthrosis, and occasionally a pivot shift is produced if there is associated anterior cruciate insufficiency. The mediolateral grind test may be positive in up to 68% of cases with meniscal pathology: however, its accuracy depends on the subjective interpretation of the examiner. If the grind test is used in conjunction with the McMurray and Apley maneuvers, a positive response may be elicited in up to 79% of meniscal lesions. The accuracy of the McMurray, Steinmann and Apley tests depends on relaxation of the patient, configuration of the tear and most importantly, the experience of the examiner. The McMurray test is impossible to perform in the presence of even a moderately tense effusion because this prevents full knee flexion.
Jump Sign. A hyper-mobile posterior horn of the meniscus, with or without a tissue bridge, may become incarcerated between the femoral and tibial condyles during the motion of flexion and extension. This situation may lead to a snapping mechanism reported by the patient or occasionally elicited by the examiner. It is usually associated with anterior cruciate insufficiency. During examination for an anterior drawer sign, the femoral condyle rides up onto the posterior horn of the meniscus and then snaps back into its normal position. This jumping of the femur may be palpable or audible and is referred to as the 'sign del salto' or the Finocchietto jump sign. With severe ligamentous instability involving primary and secondary restraints, both condyles may do it as the tibia subluxes forwards with a snap, and it has been described as the 'box' sign.
Duck Waddle. In an otherwise healthy individual presenting with vague chronic symptoms suggestive of meniscal pathology, particularly if the history include intermittent effusion, the 'duck waddle' may be helpful in provoking symptoms and localizing the site of pain. It is a non-specific test. With even a small effusion it is often impossible for the athlete to fully flex both knees, which is manifested by one buttock being higher than the other when viewed from behind. Significant retropatellar changes produce excessive patellar pain and prohibit completion of the test. Meniscal lesions are usually uncomfortable and refer pain to the particular joint line involved.
Knee Meniscal Meniscus Degenerate Horizontal Cleavage Tear litigation movies. This information is taken from I.A. Kapandji's The Physiology of the Joints Volume Two The Lower Limb, D.C. Reid's Sports Injury Assessment and Rehabilitation, and the Oxford Textbook of Sports Medicine.