Internal derangements of the knee (IDK)<br />It is a term used to cover a group of disorders involving disruption of the normal functioning of the ligaments or cartilages (menisci) of the knee joint.<br />
ANATOMY OF KNEE JOINT<br /> Bones & Articulations Largest joint in the body Synovial hinge type of a joint <br /> Mainly articulation of four bones ;femur, tibia, patella, <br /> fibula<br /> Each articulation covered with hyaline cartilage; <br /> The primary articulation between Condyles of femur & tibia <br />
LIGAMENTS <br /> Dense structures of connective tissue that fasten bone to bone & stabilise the knee. <br /> Inside the knee are two major ligaments-anterior & posterior cruciate ligaments <br />
<ul><li>Two other ligaments are located outside the knee –Medial & Lateral collateral ligaments. They act to stabilise knee sideways motion.
The patellar tendon connects lower part of patella with upper part of tibia. Part of this tendon is used in Reconstructing a torn ACL </li></li></ul><li>MENISCI Two menisci are in each knee. <br />Act as shock absorbers & also help in spreading weight .<br />A meniscus is frequently torn at the same time as ACL tears during injury. <br />
Classification<br /><ul><li>The following disorders may be met with:-
Sprain or tear of the medial collateral ligament.
Sprain or tear of the lateral collateral ligament.
Partial or complete rupture of the anterior cruciate ligament.
Cyst of a semilunar cartilage, usually the lateral.
THE COMMONEST DERANGEMENT IS MEDIAL COLLATERAL LIGAMENT INJURY FOLLOWED BY MEDIAL MENISCUS INJURY AND ACL</li></li></ul><li>Aeitology<br />Physical trauma is the cause of the vast majority of IDKs. <br />The majority of acute knee injuries result from a valgus and/or twisting strain. Most commonly, they involve the medial joint structures and the anterior cruciate ligament.<br />The type of physical trauma causing IDK may be a sports injury, a road traffic accident or an occupational stress; by far the most common at the present time is a sports injury.<br />
The most frequent cause of damage to the medial collateral ligament is forced valgus injury to the knee<br />Lateral collateral ligament injuries are much less common, as varus stress to the knee occurs much less frequently than valgus stress.<br />Anterior cruciate ligament injury occurs from forced valgus stress to the fully extended knee. <br />Posterior cruciate ligament injury is liable to occur in motor car accidents caused by high velocity trauma, with posterior dislocation of the tibia on a flexed knee, as in a dashboard impact<br />
Meniscus tears occur when substantial rotational stresses are applied to the flexed knee. They are particularly common in footballers, when the player is tackled from the side; they are also liable to occur in other sports such as hockey, tennis, badminton, squash and skiing.<br />
MEDIAL COLLATERAL LIGAMENT<br /> Anatomy:<br /> MCL is composed of superficial & deep portions<br /> superficial MCL<br /> anatomically this is the middle layer of the Medial compartment<br /> proximal attachment: posterior aspect of medial femoral condyle. distal attachment: metaphyseal region of the tibia, upto 4-5 cm distal to the joint, lying beneath the pesanserinus<br /> <br />
function:<br /> provides primary restraint to valgus stress at the knee providing from > 60-70% of restraining force depending on knee flexion angle: <br /> at 25° of flexion, the MCL provides 78% of the support to valgus stress; <br /> at 5° of flexion, it contributes 57% of the support against valgus stress;<br />
superficial ligament can be divided into<br /> anterior & posterior portions;<br />anterior fibers of superficial portion of<br />ligament appear to tighten with knee flexion<br />of 70 to 105 deg;<br />posterior fibers form the posterior oblique<br />ligament <br />
Deep MCL <br /> anatomically this is the third (deep) layer of the medial compartment which in many cases will be separated from the superficial MCL (layer II) by a bursa (which allows sliding of the tissues during flexion) <br /> divided into meniscofemoral and meniscotibial ligaments <br /> inserts directly into edge of tibial plateau & meniscus <br /> firmly attaches to the meniscus but does not provide significant resistance to valgus force<br />
Examination Findings:<br />valgus stress test<br /> clinical findings may be subtle even with complete injury; <br /> it is helpful to anchor the thigh on the table with the knee and leg off the edge of the table; <br /> opening of 5-8 mm compared to opposite knee may indicate complete tear; <br /> determine the point of maximal tenderness to determine whether the tear has occurred proximally, mid-substance, or distally; <br />
instability in slight flexion:<br /> anterior portion of the medial capsule is primary stabilizer at 30 deg of flexion;<br /> hence at 30 flexion, testing is specific for just MCL; <br />instability in extension:<br /> posterior portion of the MCL, posterior oblique ligament, ACL, medial portion<br /> of posterior capsule & possibly PCL; <br />
optimum healing of the medial collateral ligament occurs when the torn ends are in contacthealing potential is directly related to size of the gap between the torn endshealing of extra-articular ligaments is analogous to healing of other soft tissue structures, through production and remodeling of scar tissue </li></ul> maturation of scar occurs from 6 weeks to upto one year<br /><ul><li>although the maturing scar tissue has only about 60% of the strengh of the normal MCL, ultimate load to failure is unchanged (since the amount of scar tissue is larger than original ligamentous tissue) </li></li></ul><li> combined ACL/ MCL injuries<br />with concomitant MCL and ACL tears, most surgeons now recommend ACL reconstruction after the valgus stability has returned<br />the one exception might be the MCL tear arising from the tibial insertion<br />
Operative Treatment:<br />surgical plan depends on whether injury is proximal, mid substance or distal<br /> femoral avulsion:<br />with femoral avulsion, it is important to remember that reattachment anterior to its orgin may limit knee flexion where as posterior placement may cause ligament laxity the knee should be held flexed at 30 deg and held in varus when the ligament is reattached<br />
Lateral collateral ligament<br />Discussion<br />lateral collateral ligament is primary restraint to varus<br />angulation<br />LCL also acts to resist internal rotation forces <br />cutting of LCL in combination with either anterior or<br />PCL results in large increase in varus opening<br />
varus stress test<br />testing with extension:<br />LCL resists approximately 55 % of applied load at full extension<br />cruciate ligaments (primarily ACL) resist approx 25% of moment at<br />full extension<br />significant instability in full extension indicates complete LCL tear as<br />well as a tear of either the ACL or PCL ligament<br />note that LCL instability in extension which occurs with peroneal<br />palsy is a knee dislocation until proven otherwise<br />
testing with 30 deg flexion:<br />role of LCL increases with joint flexion, as posterolateral structures<br />become lax<br />with joint flexion,resistance by ACL decreases, but large forces are<br />found in PCL at 90 degrees of flexion<br />LCL is primary restraint to varus stress at 5* & 25*Flexion<br />lateral capsular structure provide secondary support<br />iliotibial band & popliteus muscles have dynamic stabilizing role<br />
Surgical Reconstruction:<br />allograft reconstruction:<br /><ul><li>With chronic posterolateral injury, Achilles tendon allograft may be indicated
Main goal is to create a checkrein to external rotation
At the level of Gerdy's tubercle, a bone tunnel is created in the posterolateral tibia, just medial to the fibular head
Attachment of the IT band to the intermuscular septum may have to be freed for optimal exposure</li></li></ul><li><ul><li>Allograft bone plug (9 mm graft and tendon) is contoured to fit the tunnel, and is secured with an interference screw
Tendinous portion of the graft is then secured in the region of the popliteus insertion with a bone anchor
Anchor site should not allow more than 3 mm of motion with knee flexion and extension
With this technique, the strong stability provided by the allograft may help compensate for disruption of the arcuate complex</li></li></ul><li>FUNCTIONAL ANATOMY OF ACL<br />The ACL is a broad ligament joining the anterior tibial plateau to the posterior intercondylor notch.<br />The tibial attachment is to a facet, in front of & lateral to anterior tibial spine.<br />Femoral attachment is high on the posterior aspect of the lateral wall of the intercondylar notch.<br />It is composed of multiple non-parellelfibres which though not anatomically separate, act as three distinct bundles i.e. anteromedial, posterolateral & intermediate. <br />
FUNCTIONS <br /> The biomechanical function of the ACL is complex for it provides both mechanical stability & proprioceptive feedback to the knee.<br /> In its stabilising role it has four main functions; 1.Restrains anterior translation of tibia. 2.Prevents hyperextention of knee. 3.Acts as a secondary stabiliser to valgus stress,<br /> reinforcing medial collateral ligament. <br />
contd…. <br />4.Controls rotation of tibia on the femur in femoral extention of 0-30 degrees. <br /> The final role is the main clinical function of ACL. <br />
ACL deficiency causes failure of this screw-home<br />mechanism,resulting in subluxation of tibia on the femur.<br />This critical function in the range of 0-30* is important for<br />movements such as side-stepping & pivotting.<br />
<ul><li>T he ligament is surrounded by synovium,thus making it extra synovial.
primarily from the middle genicular Artery which pierces the posterior capsule & enters the intercondylar notch near femoral attachment.
Additional supply comes from retropatellar pad of fat via the inferior medial & lateral geniculate arteries.
NERVE SUPPLY: Posterior articular nerve </li></li></ul><li>Rupture of ACL causes significant short term & long term disability.<br />With each episode of instability there is subluxation of tibia on the femur, causing stretching of the enveloping ligaments & abnormal shear stress on the menisci & on the articular cartilage.<br />Delay in the diagnosis & treatment gives rise to increased intrarticular damage as well as the stretching of secondary capsular ligaments. <br />
The long term outlook for an ACL deficient knee is for the development of significant osteoarthrosis. <br /> CAUSES OF ACL RUPTURE <br />1.Most common cause of ACL rupture is traumatic force applied to the knee in a twisting moment. This can occur with direct or indirect force. 2.Patients with narrow intercondylar notch are more prone to rupture their ACL. <br />
3.Patients with genurecurvatum tend to be more likely to rupture their ACL & are more difficult to treat.<br />4.Patients with generalisedligamentous disorder. <br /> 5.Familial predisposition has been found to play a role in some patients especially those who sustain bilateral ACL tears. <br />
Classical history<br />Begins with a non contact deceleration, jumping or cutting action. <br />Other mechanisms of injury include external forces applied to the knee. <br />The patient often describes the knee as having been hyperextended or popping out of the joint & then reducing. A pop is being frequently heard or felt. The patient usually has fallen to the ground & is not immediately able to get up. Resumption of activity is not possible & walking is often difficult. Within a few hours knee swells & aspiration of joint reveals haemarthosis. In this scenario ,the likelihood of ACL injury is greater than 70%. <br />
<ul><li>Examination ANTERIOR DRAWER TEST With the knee flexed to 90*, verification of relaxation of hamstrings is confirmed. With foot stabilised & in neutral rotation, a firm but gentle grip on the proximal tibia is achieved. </li></li></ul><li>An anterior force is applied to the proximal tibia with a gentle to & fro motion to assess for increased translation compared to contralateral knee. 5mm is the upper limit of anterior tibial displacement normally. <br />
Drawer sign is minimal in isolated ACL rupture. Abnormal displacement >5mm is permitted by loss of restraint by ACL & more so when associated with insufficiency of medial CL or capsular ligament.<br />When an intact PCL is rendered very taut by forcible internal rotation of tibia, it stabilises the knee to the extent that the anterior drawer sign is negated.<br />If internal rotation of tibia does not lessen the anterior drawer sign, the PCL is also insufficient. <br />
FALSE NEGATIVE ANTERIOR DRAWER SIGN<br />Especially when the ligamentous Insufficiency is confined to the ACL,the anterior drawer sign is unreliable. <br />With knee flexed to 90 degrees for classical anterior sign, medial meniscus being attached to tibia, abuts against acutely convexed surface of medial femoral condyle & has “door stopper” effect preventing or hindering anterior translation of tibia.<br />With knee extended, relationship is changed.<br />Comparatively flat weight bearing surface of femur does not obstruct forward motion of tibia when anterior stress is applied. <br />
LACHMANS TEST<br />One hand secures and stabilises the distal femur while the other hand grasps the proximal tibia.<br />A gentle anterior translation force is applied to the proximal tibia.<br />
LACHMANS TEST CONTD…<br />Examiner assesses for a firm/solid or soft endpoint.<br />Stabilisation of right knee during an examination under anaesthesia.<br />
Application of anterior tibial translation force with significant ant. translation of the tibia on the femur in an ACL deficient knee.<br />When veiwed from side,<br /> a silhoutte of the inferior<br /> pole of patella,<br /> patellar tendon & <br /> proximal tibia shows slight<br /> concavity.<br />Disruption of ACL & <br /> anterior translation of tibia <br /> obliterates the patellar<br /> tendon slope. <br />
PIVOT SHIFT TEST<br />Patient rotated 20* from supine towards the unaffected side. With slight distal traction on the leg,avalgus & internal rotation force is applied to the extended knee.<br />
With maintainance of force noted above,the knee is flexed past 30*<br />
Pivot shift in an ACL deficient knee,in the initial stages of knee flexion,the tibia will be anterolaterallysubluxed on the distal femur with application of valgus & internal rotation at the knee.<br />
With further flexion of knee(past 30*) the illiotibial band goes from an extendor to flexor of knee & tibialanterolateralsubluxation reduces back in place.<br />
Isolated tear produces only small subluxation, greater subluxation occurs when lateral capsular complex or semimembranosus corner also is deficient.<br />DISADVANTAGES:<br />Severe valgus instability may make this test difficult to do because of lack of medial support. <br /> FLEXION ROTATION DRAWER TEST<br /> Combines anterior drawer & pivot shift test.<br /> Mild degree of valgus stress & anterior pressure on upper calf are applied to elicit the positive test. <br />
ARTHOSCOPY:Acute complete tear most often found through the midportion & may appear ragged.Less often it is torn at its either end.<br />
Roentgenographic studies:<br />Plain roen.often are normal, however,a tibial eminence fracture indicates an avulsion of the tibial attachment of ACL.MRI is the most helpful.<br />
MRI FINDINGS:<br />1.PRIMARY SIGNS: Nonvisualisation<br /> Disruption of the substance of ACL by increased abnormal signal intensity<br /> Abrupt angulation<br /> Wavy appearance <br /> Abnormal ACL axis.<br />2.SECONDARY SIGNS:<br />Segonds fracture<br />osteochondral fracture <br /> Anterior translation of tibia<br /> Pivot shift<br /> Bone bruises.<br />
LEFT-Normal ACL in axial plane; <br /> RIGHT: Non-visualisation as primary sign of ACL tear with ill-defined edema & haemorhage in the usual location of the ACL in the I/C NOTCH. <br />
ACL tear with non-linearity of ligament; mild angulated ACL<br /> segonds fracture in a patient with ACL tear.<br />
Anterior translation of tibia as a secondary sign of ACL tear. <br />Tangential line to the posterior margin of tibia passes through the posterior horn of lateral Meniscus (uncovered meniscal sign).<br />In normal knee, this line passes posterior to the meniscus.<br />
TREATMENT OF RUPTURED ACL:<br />Conservative or non-operative Rx<br />Surgical Rx<br />Indications of non-operative Rx<br /><ul><li>isolated ACL tears ; likely to be succesfull in patients with partial tears & no instability symptoms.
complete tears & no symptoms of knee instability during low demand sports who are willing to give up high demand sports
Who do light manual work or live sedentary habits
Whose growth plates are still open(children) </li></li></ul><li>NON-OPERATIVE RX:- consists of<br /><ul><li>Progressive physical therapy & rehabilitation can restore the knee to a condition close to its preinjury state.
Educate the patient how to prevent knee instability.
This may be supplemented with the use of hinged knee brace.</li></li></ul><li> OPERATIVE RX<br /> INDICATIONS<br />Patients with knee instability, pain, swelling or giving way should consider surgical reconstruction of the knee.<br />In some cases reconstruction is necessary because of damage to menisci or articular cartilage of the knee.<br />Progressive premature degenerative changes in patients with unstable knee may also be an indication. <br />
CHOICE of RX mainly depends on assesment of three patient factors:<br />AGE: The child ,the adolescent, the young adult, the middle aged & the elderly represent different surgical problems.<br />FUNCTIONAL DISABILITY:<br />It may vary from undiagnosed asymptomatic rupture to a patient whose knee gives way on daily basis.<br />
FUNCTIONAL REQUIREMENTS:<br /><ul><li>Vary from sedentary patients with low activity requirements, through those patients with an active social sporting life or physically demanding work, to the elite athelete whose fame & fortune depends upon a highly functional knee.
Rupture of ACL in the child or elderly is very rare & are usually Rx conservatively.
Rupture in the adolescent is not uncommon & presents its own problems because of skeletal immaturity. Most isometric reconstructions place the growth plate at risk.</li></li></ul><li><ul><li>Reconstruction may be delayed up to skeletal maturity. However, in elite adolescent athelete with an acute rupture it is possible to repair the ligament early & to supplement this with semitendinosus & gracilis reconstruction. This is possible by performing surgery within the epiphysis.
Vast majority of patients fall in to young adult & middle aged persons. Males are more frequently seen than females though this pattern is reversed in skiers where a disproportionate no. of female skiers are injured.</li></li></ul><li>Before any surgical Rx, patient is sent to physical therapy.<br />Resolution of inflammation & return of full motion reduce the incidence of postoperative stiffness<br />It usually takes 2 to 3 weeks from the time of injury to achieve full range of motion.<br />It is also recommended that some ligament injuries be braced & allowed to heal prior to ACL surgery. <br />
Surgical options<br />Repair of ACL either isolated or with augmentation. <br />Reconstruction with either autograft, allograft or syntheticsp<br />Primary repair of the ACL is no longer recommended because repaired ACL have generally been shown to fall overtime.<br />The torn ACL is generally replaced by a substitute graft made of tendon.The grafts commonly used:<br /> PATELLAR TENDON AUTOGRAFT;HAMSTRING TENDON;QUADRICEPS TENDON<br />
POSTERIOR CRUCIATE LIGAMENT:ANATOMY <br />Intra-articular but extrasynovial, static stabiliser of knee:<br />composed of two major parts:Large anterior part that forms the bulk of the ligament & a smaller portion that runs obliquely to the back of tibia.<br />PCL is attached proximally to the posterior part of the latral surface of the medial condyle.Thetibial attachment is to a depression behind & below the intra-articular portion of tibia with a slip usually blending with the posterior horn of the latral meniscus.<br />
Origin & insertion sites of posterior cruciate ligament:<br />
Biomechanics: <br />Progressive tightening of the PCL occurs during internal rotation of tibia with the knee in either flexion or full extension.<br />Also in full extension the PCL allows only minimal abduction or adduction widening of the knee despite complete removal of accessory supports;the extensor retinaculum, capsular ligaments, collateral ligaments & posterior capsule.<br />This fact emphasis the importance of the PCL as the basic stabiliser of the knee, while the ACL & collateral ligaments augment its stabilising effect.<br />
Functions<br /><ul><li>provides restraint against hyperextension,
against posterior displacement of tibia in flexed knee,
valgus/varusangulation-particularly in extended knee.</li></li></ul><li> ACUTE TEAR: Requires much more force than to tear ACL.<br />Following ways:<br />1.Severe rotational injury; an external rotation-valgus injury or an internal rotation-varus injury produces tear of PCL assoc. with disruption of MCL or LCL.The PCL is interupted at its midportion or at its femoral attachment.<br />2.Hyperextension injury: Tibial attachment is avulsed usually<br />3.Direct trauma to upper tibia while the knee is flexed-Dashboard injury.<br />4.Complete dislocation of knee. <br />
CLINICAL PICTURE:<br /><ul><li>History of severe trauma is elicited.
Degree of both immediate pain & inability to bear weight on the injured knee is highly variable.
These are more pronounced when capsule is intact & haemarthrosis is confined within the joint.
They may be minimal when the posterior capsule is disrupted & blood escapes from the joint.</li></li></ul><li><ul><li>Objective findings are:
Posterior drawer sign in allmost 60% of cases. </li></li></ul><li>POSTERIOR DRAWER TEST<br />With knee flexed to approx. 90*, verification of complete relaxation of hamstrings is confirmed by palpation .<br />
With foot in neutral rotation & stabilised, a firm but gentle posterior translation force is applied to proximal tibia.<br />Initial starting point for a posterior drawer test(foot in NR, knee flexed to 90*)<br />
Application of posterior translation force results in posterior subluxation of tibia on the femur in a patient with PCL deficient knee.<br />
TIBIAL BACK DROP TESTIn this test, the examiner compares the prominence of the proximal tibiato the femoral condyles with the knee flexed to 80*.In a PCL deficient knee, the knee will be posteriorlysubluxed due to gravity.<br />
In a normal knee at 80* the tibial plateau is located approximately 1cm anterior to the femoral condyles<br />
TIBIAL BACK DROP TEST IN A PCL DEFICIENT LEFT KNEE<br />NORMAL CONTRALATERAL RIGHT KNEE.<br />
QUADRICEPS ACTIVE TEST:<br />It is performed with the knee flexed to 80deg & in neutral rotation.Its starting point is in effect the tibial drop back test.<br />
<ul><li>From its initial relaxed position, the patient is asked, to contract Quadriceps muscle (straighten out his leg without extending his knee) while examiner applies counter pressure against the ankle.</li></li></ul><li>Quadriceps pulls anteriorly through the tibial tubercle to reduce any posterior translation in the knee.<br />Reduction of a posteriorlysubluxed tibia with Quadriceps contration in a PCL deficient knee.<br />
Contraction of the quadriceps muscle in a knee with a PCL deficiency results in an anterior shift of >2mm.<br />
ROENGENOGRAPHIC FINDINGS:<br /><ul><li>Plain radiographs usually normal.
Stress radiography assists in the diagnosis of PCL injuries.
Increased posterior translation of 8mm or more in stress roeng.is indication of complete rupture.
A contrast arthogram may reveal evidence of ligament disruption.
Arthroscopic evaluation should be done to assess the damage to both the cruciates & to define additional lesions.</li></li></ul><li>MRI studies are more reliable for diagnosis of PCL tears than ACL tears.<br />
TREATMENT OF PCL INJURIES:<br />NON-OPERATIVE TREATMENT: <br /> The quoted criteria for non-operative RX include:<br />(1).A posterior drawer test of < 10mm with the tibia in neutral rotation(posterior drawer excursion decreases with internal rotation of tibia on femur).<br />(2). < 5* of abnormal rotatory laxity(specifically, abnormal external rotation of the tibia with the knee flexed 30*,indicating posterolateral instability).<br />(3).No significant valgus-varus abnormal laxity. <br />
OPERATIVE TREATMENT<br />Reconstruction is usually delayed for 1 to 2 weeks after injury to allow painful intra-articular reaction to subside & to allow the patient to regain full motion and some strength.<br />Clinically, isolated acute PCL disruptions are repaired if the ligament is avulsed with a fragment of bone.<br />Knee is examined arthroscopically before any open surgical procedure.<br />
RX alogrithm for PCL avulsion fracture:<br />
Screw reattachment of bone fragment avulsed with PCL from posterior tibia. <br />
RECONSTRUCTION OF PCL:Can be done by open or Arthroscopic technique;arthroscopic technique is prefered.<br />Various grafts used are : <br /> (1).Patellar tendon graft. (2).Bone-patellar tendon-bone graft. (3).Tendo-achillis bone graft. (4).Illiotibial band. (5).Medial head of gastrocnemius tendon. (6).Hamstring tendon. (7).Lateral meniscus.<br />
COMPLICATIONS OF PCL RECONSTRUCTION<br />Loss of motion is the most common complication aside from from usual postoperative complication.<br />Flexion loss is more common than extension loss.<br />Failure to obtain objective stability is another common complication.<br />Failure of reconstruction may be the result of untreated associated ligamentous injuries such as the posterolateral corner, which allow excessive forces to be applied to the graft. <br />
<ul><li>Neurological complications(injuries) can result from excessive tourniquet time & manifest as neuropraxia.
Vascular complicatons include laceration, thrombosis,& intimal injury to the poplitealartery.Viewing the tip of reamer & guide pin at all times can prevent this injury.
Osteonecrosis of medial femoral condyle has been reported-cause thought to be local trauma to the subchondral bone from both soft tissue dissection & drilling. </li></li></ul><li>MENISCUS INJURY<br />
Anatomy<br /><ul><li>The menisci are C-shaped or semicircular fibrocartilaginous structures with bony attachment at anterior and posterior tibial plateau. The medial meniscus is C-shaped, with a posterior horn larger than the anterior horn in the anteroposterior dimension.
The capsular attachment of medial meniscus on the tibial side is referred to as the coronary ligament. A thickening of the capsular attachment in the midportion spans from the tibia to femur and is referred to as the deep medial collateral ligament. </li></li></ul><li>The lateral meniscus is also anchored anteriorly and posteriorly through bony attachments and has an almost semicircular configuration. It covers a larger portion of the tibialarticular surface than does medial meniscus<br />
<ul><li>The fibrocartilaginous structure of the meniscus has a varied architecture of coarse collagen bundles.
By age 9 months, the inner one-third has become avascular. This decrease in vascularity continues by age 10 years, when the meniscus closely resembles the adult meniscus. </li></li></ul><li><ul><li>In adults, only 10 to 25% of the lateral meniscus and 10 to 30% of the medial meniscus is vascular. This vascularity arises from superior and inferior branches of the medial and lateral genicular arteries, which form a perimeniscal capillary plexus.
Because of the avascular nature of the inner two-thirds of the meniscus, cell nutrition is believed to occur mainly through diffusion or mechanical pumping.</li></li></ul><li>The classification of meniscal tears provides a description of pathoanatomy. The types of meniscus tears are:<br />Longitudinal tears that may take the shape of a bucket handle if displaced <br />Radial tears<br />Parrot-beak or oblique flap tears <br />Horizontal tears and <br />Complex tears that combine variants of the above.<br />
History<br />Most meniscal injuries can be diagnosed by obtaining a detailed history.<br />
Mechanism of injury <br />Meniscus tears are sometimes related to trauma;but significant trauma is not necessary. <br />A sudden twist or repeated squatting can tear the meniscus.<br />Meniscus tears typically occur as a result of twisting or change of position of the weight-bearing knee in varying degrees of flexion or extension.<br />
<ul><li>Pain from meniscus injuries is commonly intermittent; usually the result of synovitis or abnormal motion of the unstable meniscus fragment & is localized to the joint line.
Mechanical complaints: Descriptions by patients are often nonspecific but include reports of clicking, catching, locking, pinching or a sensation of giving way.
Swelling usually occurs as a delayed symptom or may not occur at all. Immediate swelling indicates a tear in the peripheral vascular aspect.
Degenerative tears often manifest with recurrent effusions due to synovitis.</li></li></ul><li> Physical findings<br /> Joint line tenderness <br /><ul><li>Joint line tenderness is an accurate clinical sign.This finding indicates injury in 77-86% of patients with meniscus tears. Despite the high predictive value, operative findings occasionally differ from the preoperative assessment.
The examiner must differentiate collateral ligament tenderness that may extend further toward the ligament attachment sites above and below the joint line.</li></li></ul><li><ul><li>Effusion
Effusion occurs in approximately 50% of the patients presenting with a meniscus tear.
The presence of an effusion is suggestive of a peripheral tear in the vascular or red zone (especially when acute),an associated intra-articular injury, or synovitis.
A mechanical block to motion or frank locking can occur with displaced tears.
Restricted motion caused by pain or swelling is also common.</li></li></ul><li>Provocative maneuvers<br /><ul><li>These techniques cause impingement by creating compression or shearing forces on the torn meniscus between the femoral and tibial surfaces.</li></li></ul><li> The McMurray test:<br /><ul><li>This maneuver usually elicits pain or a reproducible click in the presence of a meniscal tear.
The medial meniscus is evaluated by extending the fully flexed knee with the foot/tibia internally rotated while a varus stress is applied.
The lateral meniscus is evaluated by extending the knee from the fully flexed position, with the foot/tibia externally rotated while a valgus stress is applied to the knee.
One of the examiner's hands should be palpating the joint line during the maneuver.</li></li></ul><li>The Steinmann test:<br />Tibial rotation is performed with the patient seated and the knee flexed 90*.Asymmetric pain is created with external (medial meniscus) or internal (lateral meniscus) rotation.<br />The Apley test:<br /> This maneuver is performed with the patient prone and the knee flexed 90*. An axial load is applied through the heel as the lower leg is internally and externally rotated. This grinding maneuver is suggestive of meniscal pathology if pain is elicited at the medial or lateral joint.<br />
Articular cartilage pathology including arthritis
Crystalline deposition diseases including gout and pseudogout (chondrocalcinosis)
Ipsilateral hip disease:Osteonecrosis of the femur or tibia</li></li></ul><li>Imaging Studies<br /><ul><li>Plain radiography: An AP weight-bearing view, PA 45* flexed view, lateral view and Merchant patellar view should be obtained to rule out degenerative joint changes (arthritis) or fractures
Arthrography: Historically, arthrography was the standard imaging study for meniscal tears but it has been replaced now by MRI.
MRI: This is the standard imaging study for imaging meniscus pathology and all intra-articular disorders. </li></li></ul><li>Treatment<br />
<ul><li>A home physical therapy program or simple rest with activity modification, Ice and NSAIDs is the nonoperative management of possible meniscus tears.
The physical therapy program goals are to minimize the effusion, normalize gait, normalize pain-free range of motion, prevent muscular atrophy, maintain proprioception and maintain cardiovascular fitness. Choosing this course of treatment must include consideration of the patient's age, activity level, duration of symptoms, type of meniscus tear, and associated injuries such as ligamentous pathology
A trial of conservative treatment should be attempted in all but the most severe cases, such as a locked knee secondary to a displaced bucket-handle tear</li></li></ul><li> Medical Issues/Complications<br /><ul><li>The main complication at this stage of treatment is the absence of healing and failure of symptoms to resolve.
The natural history of a short (<1 cm), vascular, longitudinal tear is often one of healing or resolution of symptoms.
Stable tears with minimal displacement, degenerative tears, or partial-thickness tears may become asymptomatic with nonoperative management.</li></li></ul><li>Most meniscal tears do not heal without intervention.<br /><ul><li>If conservative treatment does not allow the patient to resume desired activities, his or her occupation, or a sport, surgical treatment is considered.
Surgical treatment of symptomatic meniscal tears is recommended because untreated tears may increase in size and may abrade articular cartilage, resulting in arthritis </li></li></ul><li>Surgical Intervention<br /> Indications:- <br /><ul><li>Symptoms persist.
If the patient cannot risk the delay of a potentially unsuccessful period of observation.
Principle of meniscus surgery is to save the meniscus.
Tears with a high probability of healing with surgical intervention are repaired.
Most tears are not repairable and resection must be restricted to only the dysfunctional portions, preserving as much normal meniscus as possible.</li></li></ul><li>Surgical options include partial meniscectomy or meniscus repair (and in cases of previous total or subtotal meniscectomy, meniscus transplantation). <br /><ul><li>Arthroscopy, a minimally invasive outpatient procedure with lower morbidity, improved visualization, faster rehabilitation, and better outcomes than open meniscal surgery, is now the standard of care.</li></li></ul><li><ul><li>Partial meniscectomy is the treatment of choice for tears in the avascular portion of the meniscus or complex tears that are not amenable to repair.
Meniscus repair is recommended for tears that occur in the vascular region (red zone or red-white zone), are longer than 1 cm, involve greater than 50% of the meniscal thickness, and are unstable to arthroscopic probing. </li></li></ul><li><ul><li>Human allograft meniscal transplantation is a relatively new procedure but is being performed increasingly frequently.
Specific indications and long-term results have not yet been clearly established.
Meniscus transplantation requires further investigation to assess its efficacy in restoring normal meniscus function and preventing arthrosis.</li></li></ul><li><ul><li>Recovery Phase
Physical Therapy</li></ul>Physical therapy during recovery is directed toward the same goals as those in the acute phase.<br />For partial meniscectomy, patients may return to low-impact or nonimpact workouts such as stationary cycling or straight-leg raising on the first postoperative day and may advance rapidly to preoperative activities<br />
<ul><li>When a meniscus repair is performed, the rehabilitation is typically more intensive.
Three main issues are considered in the rehabilitation of meniscus repairs: knee motion, weight bearing, and return to sports.
A common protocol is avoidance of weight bearing for 4-6 weeks, with full motion encouraged.</li></li></ul><li>Complications<br /><ul><li>Reported complication rates for arthroscopic meniscectomy range from 0.5-1.7% and these can occur intraoperatively or postoperatively.
Intraoperative complications include anesthetic problems, articular cartilage damage, vessel or nerve injury or instrument failure.</li></li></ul><li><ul><li>Postoperative complications include anesthetic concerns, thrombophlebitis, hemarthrosis, infection, stiffness, persistent pain, effusion or synovitis.
Reported complication rates for meniscus repairs range from 1-30%.
The list of complications is the same as that for meniscectomies, with a greater concern for neurovascular injury. Additionally, failure to heal or meniscalreinjury can occur.</li>