Presentation on theme: "Musculoskeletal Diseases and Disorders: Knee and Patella"— Presentation transcript:
1Musculoskeletal Diseases and Disorders: Knee and Patella PTP 521
2Fractures Knee Ottawa Rules A knee x-ray is only required for knee injury patients with any of these findings:age 55 or overisolated tenderness of the patella (no bone tenderness of the knee other than the patella)tenderness at the head of the fibulainability to flex to 90 degreesinability to weight bear both immediately and in the casualty department (4 steps - unable to transfer weight twice onto each lower limb regardless of limping).
3FRACTURES OF THE KNEE AND PATELLA Fractures of the Distal Femur Classified by location Supracondylar: occur superior to the femoral condyles. Common patterns are comminuted, impaction, linear, with or without displacement
4Intercondylar: Occurs between the medial and lateral femoral condyles. Fracture pattern is commonly called a "Y" fracture.Condyles split apart from each other and from the shaft of the femur.
5Condylar Usually linear and involves only one femoral condyle Sartoris, Adductors,
6Fractures of the Proximal Tibia Most frequent occurrence is at the medial and Lateral tibial plateaus with the lateral plateau most often involved. -difficult to see and treat. Mechanism of injury is a varus or valgus force combined with axial compression. Generally considered to be impaction fractures.
7Because of the difficulty in viewing the tibial plateau, conventional tomography is needed in addition to the routine x-rays.A classification system has been developed to identify the 6 most common fracture patterns.
8Tibial Plateau Fractures Two systems: book has the Hohl system highlighted very well.Second system is the scharzker method.The web site above has a great representation of the Scharzker classification with a unique way of viewing the CT scans. The cursor can move over the radiograph and the picture below shows the corresponding CT view.These two systems are not very different.Hohl and Scharzker = need to recognize that they are tibial plateau fractures, but then can go look up.Higher they go the more rehab needed, as they get worse.
9Comparison Hohl Classification Schatzker Classification Same as Hohl Type IType IIIType IISame as Hohl Type IVSame as Hohl Type VSame as Hohl Type VIType IType IIType IIIType IVType VType VIMain difference between the two classifications is the placement of Type II and TypeIII which are switched in the two classification types. Be sure you see whichclassification is being used when dealing with a tibial plateau fracture to understandthe bone dysfunction.
10Hohl SystemHohl Type I: nondisplaced vertical split fracture of the lateral tibial plateau caused by a pure valgus forceSchatzker Type I: Pure split on lateral side
11Hohl Type II: a local depression of the lateral tibial plateau caused by a combination of axial and valgus forcesSchatzker Type III: Pure central depression - Lateral condyle
12Hohl Type III: a displaced vertical split fracture with depression at the lateral plateau, caused by a combination of valgus and axial forces and often associated with a proximal fibula fracture.Schatzker Type II: Split with lateral depression
13Hohl Type IV: a displaced depressed fracture of the medial plateau, caused by varus and axial forces Schatzker Type IV:fractures of medial condyle
14Type V: a vertical split fracture of the anterior or posterior aspect of the tibial plateau, caused by axial forcesSchatzker Type V: Bicondylar fractures Continuity of metaphysis & diaphysis maintained
15Hohl Type VI: a displaced, comminuted fracture of both condyles, caused by axial forces, often associated with proximal fibula fracturesSchatzker Type VI: Dissociation of metaphysis & diaphysis in addition to plateau
16Fractures of the Patella MOI: direct trauma from falls or blows or indirect trauma from tension forces.-change in force, action of muscle.Direct trauma:Patella fractures as it compresses against the femur.Most frequent pattern is a transverse linear fracture line through the mid-region of the bone.Vertically oriented fractures and comminution are also seen.Avulsion fractures of the patella occur as a result of indirect trauma
18Patella Fractures Patella fractures Lateral view AP view Sunrise view Patella AltaAvulsion fracture of patella ligament
19AP and Lateral Views of the Displaced Transverse Fracture of the Patella
20Sunrise view: MRI On the left is a patella dislocation, high signal intensity on the lateral sideView on the right is a bipartite patella. Can be confused with a fractured patella
21Full thickness fissure of the patella articular cartilage
22Joint effusionTransverse View, fast spin echo T2-weighted fat saturated MRNormal cartilage with joint effusion surrounding it
23Joint Dysfunctions of the Knee Rheumatoid Arthritis: discussed under wrist and handRheumatoid arthritis. Anteroposterior knee radiograph shows diffuse uniform joint space narrowing.Bone on Bone, uniform narrowing.Jacobson J A et al. Radiology 2008;248:
24Osteochondritis Dessicans Definition: avascular necrosis of the condylar epiphysis of the femur Medial femoral condyle involved in 75% of the cases, lateral condyle can also be affected, results in a osteochondral fracture
25Etiology: traumaticCaused by impingement of the tibial spine on the femoral condyleOr a loss of circulation to the osseous tissue of the epiphyseal plateOr an avulsion of the proximal attachment of the PCL
26SX: Signs: aching pain in the knee at rest worse with weight bearing activitiesinsidious onsetepisodes of knee joint lockingSigns:antalgic gait patternknee joint effusionrestriction in range of motion present
27Radiographs:AP, lateral, and tunnel will show a lesion that appears like a half moon defect on the subchondral boneRX:Decrease or elimination of WB with immobilization
28Osteonecrosis: Avascular necrosis of the knee occurring in adults, Typically women age 50 years or more.Medial compartment of the knee and femoral condyle more involved than tibial condyle.
30DJD/OA of the knee Standing AP view of the knee’s Weight Bearing Important.Typical finding is sharpening of the tibial spinesNarrowing of the medial compartment
31This view shows osteophyte formation on the tibial plateau, medial side Narrowing of both the medial and lateral compartments, but more on the medial.More advanced OA
32Patello Femoral OA seen in a lateral view Patellofemoral compartment narrowingOsteophyte formation on both the superior and inferior aspect of the patellaTry bending this kneePatella will have more pain in flexion (stairs) , but relief in extension
33Surgeries: High Tibial Ostotomy Occurs in patients with unicompartmental osteoarthritis.Usually the medial compartment with a varus deformity noted.New but effective.Patients age is usually under 65 years of age, generally exclude patients with RA or other systemic diseases
34Indications for Tibial Osteotomy Best results occur in patients under 50 years of ageBody mass index greater than 25 kg per square meter?Isolated medial compartment OA,No lateral thrust at the knee,A varus deformity less than 10 dgRange of motion greater than dgSteve Iserman
35Contradictions Inflammatory arthritis: RA, Sceriatic Arthritis Significant ligamentous instabilityAge greater than 70yearsSevere patellofemoral arthritisFlexion contracture greater than 15 dgWon’t get good contact, so bone won’t heal properly.Varus deformity greater than 15 dg
36Technique: wedge resection Lateral is lower, so more weight bearing on that lateral side..
37Goal of Surgery:Realign the weight bearing axis so that the pressure on the tibial plateau is shifted laterally into the area of the intercondylar eminence and the tibial spines rather than the medial condyle
38Unicompartmental replacement Replace only one part of the knee but maintain the natural joint/bony surfaces on the other part.Used when ACL surgery failsGenerally will replace the medial compartment.To function successfully, the anterior cruciate ligament needs to remain intact
39Total Knee Replacement Indications: a. Chronically disabling degenerative knee pain b. Failed conservative measures Contradictions: a. Acute infection elsewhere in body b. Charcot arthropathy or absence of sensation in the joint c. Infection within the joint d. Severe spasticity associated with contractures.
40Relative contra indications a. Severely demented or bedridden patients (unless needed for transfers)b. Osteoporosis (depends on bone density of femur and tibia)c. Significant peripheral vascular disease (if it won’t heal)
41Prosthetic DevicesClassified as constrained, semi-constrained, or minimally constrained constrained: actually hinges, knee doesn't function as a simple hinge though and these prostheses have a high failure rate, reserved for the patients with severe instability problems or severe deformities
42Semi-constrainedPosterior cruciate ligament is absent or taken out as a result of the surgery.This is designed to prevent subluxation or dislocation of the tibiofemoral joint resulting from the absence of the ligaments.
43Advantages and Disadvantages of the Preserving the PCL restores more normal knee kinematicsmore normal stair climbing abilitiesDisadvantagesexcessive rollback of femur on tibia if PCL is too tightdifficult to reproduce the preoperative joint lineligament length more difficult to balance with the collateral ligamentsmore difficult to correct large flexion contractures
44Minimal constrained: Reproduces the anatomical contours of the knee Relies heavily on soft tissue to provide joint stabilityUsually done with younger individuals, so can freely do activities.
46TKR Rehab: “joint camp” Goal of a TKR is to provide patient with a stable, pain-free knee joint with a functional range of motion-Usually there for 4 days or less.Postoperative Problems: knee stiffness which can lead to adhesions=work on flexion.Functional considerations: need at least 90 dg of flexion to be able to do most ADL's and greater than 90 dg's is needed to go from a sitting to a standing position.
47Patellofemoral Dysfunctions: Patella InstabilitiesPatella Dislocation: associated with an excessive lateral pull of the vastus lateralis and IT bandMOI: acute trauma or twisting force with a combination of flexing femur, externally rotating femur while foot is planted
48Subluxation of the Patella: same mechanisms as a dislocation Patella should mirror the condylar divot. Shifted slightly like seen is a subluxation. Over more would be a dislocation.
49Factors which predispose a patient to subluxation or dislocation: 1) Q angle greater than 20 dg2) Excessive external rotation of tibia (in prone)3) Increased internal rotation of the femur (stand behind and look at medial hamstrings coming at you that’s IR of femur)4) Patella alta –(high patella) considered most important, tape measure=if length of patella is shorter than distance from the posterior apex to tibia tuberosity.5) Shallow trochlear groove6) Small flat patella7) Atrophy of vastus medialis (hold patella, then do a quad set, see where it is pulled, usually lateral)8) Muscle imbalance/weakness relative tothe vastus lateralis
50SX and Signs SX: Signs: onset occurs with sudden activity valgus external rotation forceSigns:Hemarthrosis -bleeding into joint.tenderness to palpateapprehension to lateral patella joint movement
51Chondromalacia Patella Patellofemoral tracking dysfunctions: new term (to make it seem less chronic)Progressive softening, fibrillation and finally degeneration of the articular cartilage on the underside of the patella-Seen with younger girls (13-15)Overuse syndrome with altered patellar biomechanics occurring.
52Chondromalacia=SX: retropatellar pain described as aching with sitting.Signs: + movie goers sign (forced into full knee flexion for a long period of time), + full knee flexion test (takes 30 to 60 seconds for achy pain to start)
53Stages: I - IV I: swelling and softening of the cartilage II: fissuring w/in the softened areasIII: fasciclations of articular cartilage almost to level of subchondral boneIV: destruction of cartilage w/ subchondral bone exposedHistologically Stage IV is virtually indistinguishable from DJD
55Larsen-Johansson's Disease Necrosis of the patella polesoccurs in children 8-13 years of ageetiology unkown, insidious onset
56SX and SignsSX:pain with resisted extension of the knee,pain with kneeling,pain with activitySigns:swelling and tenderness to palpation over the inferior pole of the patellaX-ray: may or may not show fragmentation of the bone near the affected pole
57Musculotendinous Dysfunctions of the Knee Osgood Schlatter's Disease: Tibial Apophysisitis-inflammation of the tibial tuberosity, which goes bone growth.Develops when the epiphysis undergoes the transition from cartilage to bone.Develops in the patella tendon/bone insertion-more cosmetic, then chronic pain.
58Osgood Schlatters Disease Traction on the patella ligament results in microfractures.The body tries to heal itself and an outgrowth of the tibial tuberosity occurs.Occurs in males more than females, ages 12-14During a growth periodDifferential Diagnosis: Mechanical dysfunction, mimics patellar tendonitis or patellofemoral pain syndrome
59SX and Signs Sx: Signs: pain in the region of the tibial tubercle related to activity particularly sportspain relieved by resthurts to kneelSigns:swelling over the tibial tubercletenderness to palpation over the tibial tubercle
60Radiographs: lateral view may show irregular ossification or fragmentation of the tibial tubercle RX:Rest, may try bracing to give patella tendon some assistAvoid resisted knee extension activities until the pain has gone away.Time is usually 6-8 weeks, may castSurgery – rare*Issue how to keep kid from running and jumping when pain in minimum.
61Tendonitis Patella tendonitis or jumper's knee: SX: Signs: pain during activity,pain after activity,pain with sitting for a long period of timetenderness noted at inferior pole of patellaSigns:tenderness to palpation,pain with resisted knee extensionswelling over the patella tendon regionpain with passive stretch
62Quadriceps Tendonitis Superior pole of the patella at the tendon junction. Occurs in sports that require a lot of running and jumping or acceleration - deceleration activities like soccer or basketballSX:pain during activitypain after activitySigns:tenderness to palpate over the superior pole of the patellapain with resisted knee extensionpain with passive stretch of the quadriceps
63Iliotibial Tract Tendonitis Friction between the underlying structures and the iliotibial tract, occurs in runners or patients whose occupation or hobbies lead to a tight iliotibial tract.SX:pain with activitypain over the lateral thigh closer to the kneeSigns:+ Ober's testpain with resisted abductiontenderness to palpate over the lateral epicondyle
65Inert Tissue Dysfunctions of the Knee LigamentMedial Collateral Ligamenta. MOI: valgus force applied to the lateralaspect of the knee with the foot fixed, kneein extensionb. Less common MOI: knee in slight flexion(less than 90 dg), or twisting motion occurs
66Symptoms and Signs SX: Signs: mild tenderness at medial joint line swellingSigns:Grade I, II, or III laxity with valgus stress,AROM is painful near the end of extensionedema presentpoint tender at adductor tubercle and/or medial joint lineALWAYS check it in the position that it was injured in, also before inflammation or after it goes down.
67Stress Test Analysis Mild medial laxity with valgus stress, Knee in full extension: damage to posterior oblique ligament and capsular ligamentGross instability at full extension: check ACL and PCL to make sure they are tightEmpty end feel or indistinct end feel: secondary restraints are holding the knee, ligament is grade III
68Medial Collateral Ligament Ligaments turn up as BLACKCoronal Images used to evaluate MCL tearsProton density coronal image – arrowsShow ligament as thin, well defined, low signal intensity from medial femoral condyle to the medial tibial metaphysis
69Lateral Collateral Ligament MOI: Varus force from the medial side of the knee.Isolated injuries are rare because of ligament's location posterior to the axis of the knee joint.Not as commonly injured, as very stable.Usually injured as a torsional overload that also affects the cruciate ligaments
70Sx and Signs SX: lateral knee pain Signs: varus laxity in extension and flexionnumbness or tingling if nerve root is involved: common peroneal
71Oblique orientation, low signal structure – white arrow Inserts onto fibular headAvulsion fracture of the fibular head may be seen on plain film radiographs with aLCL injury
72LCL and MCL tear LCL is outside the capsule, A tear in the LCL does notCause as much effusion asA MCL tear. You will not seeAn increased signal intensityAround the ligament as youdo in an MCL tear.See figure to the right.
73Anterior Cruciate Ligament: MOI: combination of valgus and external rotation forces applied to the knee while foot is in a closed pack positionLess common MOI: excessive internal rotation and hyperextension combinationnon contact injury in which sudden limb deceleration is accompanied by a contraction of the quads producing damaging force momentsCommonly the MOI for woman.
74ACL Tear Arrow’s point to the tear Less formation of the tendon
76Triad of images showing an ACL tear Top left: T2 Sagittal view Top right: T2 coronal viewBottom: T1 coronal view,
77Anterior Cruciate Ligament Repair: sew the tear.Replacement: take out old, but in a new.
78SX and Signs SX: Patient reports a "pop" at time of injury Knee swelling within one hour after injuryHemarthrosis within 12 hoursSigns:+ Lachman's+ pivot shift test+ anterior drawer testHamstring muscle spasm: can give a false negative as they protect any movement from anterior drawer.Inability to fully weight bear on affected sideWeakness and knee giving way are frequent occurrences
79Chronic problemFrequent episodes of knee giving out. Pain and effusion with specific activities that stress knee such as cutting and pivotingRX: depends on the degree of tear, Will generally wait 2-3 weeks until the swelling has decreased before going in and assessing the ligamentMRI is diagnostic as is arthroscopic surgerySurgery: Type of graft used will depend upon the physician. Great controversy in the literature regarding the graft type.
80Patella - Tendon Graft: Central third of the patella tendon is taken to use as a graft, so quads will be affected.Considered to be 57% as strong as original ACL at 3 months and 87% as strong at 12 months.At first will decrease in strength, but eventually will remodel and become stronger.Some take the tendon from the opposite side, as will have balance out, but now will have issues on both side.
81Two type of Patella Tendon grafts: Injured leg.Have to deal with two injuries then, a decrease in the quad mechanism and the ACL repairSecond is taken from the uninvolved leg.Gives a strong patella tendon on the ACL side but a weaker tendon on the opposite side (Shelbourne Procedure)
82Semitendinosus and Gracilis Grafts Provide weaker initial fixation and have a more prolonged and variable rate of fixation into the bone than does the central third patella grafts.Used when there is a significant incidence of patellofemoral and anterior knee pain associated with the injuryWeakening the hamstring.
83These tendons can be removed, doubled over, and then used to replace the ACL. These tendons are easier to harvest than the patellar tendon, they require smaller drill holes in the femur and the tibia for fixation, and they do not predispose patients to patellar tendinitis.
86Allografts: Cadaver grafts Indications:Failed autograft surgerySignificant patellofemoral arthrosisNarrow patella tendonPatients who don't want to use their own tissue3 areas of concern:1. Immune reaction2. Potential disease transmission3. Remodeling and effect on mechanicalproperties
87Posterior Cruciate Ligament MOI: anteromedial blow to the flexed knee or a fall onto the knee with foot and ankle plantarflexedCommon component is the posteriorly directed force on the proximal tibia which pushes the tibial plateau posterior on the femoral condyles
88PCL: All three images should be used, sagittal, coronal and axial T1 Coronal ImageDarker arrow is the PCL and is a lower intensity signal than the ACLLighter arrow is the ACL
89Sagittal View Proton dense sagittal image Insertion site (arrows) is posterior to the tibia articulating surface
90Avulsion fracture of the PCL as demonstrate on an AP radiograph
91Interstitial tear of the PCL A: proton density sagittal image B: T2-weighted sagittal image
92Mid substance tear of the PCL- large arrow Proton dense-weighted sagittal viewIntact PCL proximally, tear, edema noted mid PCLLigament of Humphrey – small arrow
93SX and Signs: Signs: Sx: ROM is usually WNL Difficulty weight bearing Painful on end range flexionExtensor lag present (tibia drops below the femur)+ posterior drawer test+ tibial sag test+ hughston testSx:Difficulty weight bearingPainfulInstability with stairs and inclinesRecurrent swelling
94SurgerySurgery is controversial if only PCL is ruptured, Grade I PCL injuries with less than 5 mm of increased posterior translation of the tibia are managed non-operatively.
95Surgical Reconstruction Surgical reconstruction is recommended for isolated PCL disruption that result in 10 mm if increased posterior tibial translation.Also used with PCL injuries combined with injury to other ligamentous structures
96Inert Structure Dysfunctions Meniscus: Medial meniscus is more frequently injured than the lateral meniscus. (similar to SLAP lesions of the GH) Location of the tear will dictate the response to injury a. periphery: good repair, vascular, get a fibrocartilage scar tissue b. central portion, avascular, poor repair
97Tears: MOI: traumatic, occurs in the 13 to 40 year olds, occurs with activity that may or may not be contact relatednon-contact: acceleration or deceleration stresses combined with a sudden change in direction, squatting or twistingproduces a longitudinal or transverse vertical tear
98Types of Tears www.health.allrefer.com Stoller, D. Pocket Radiologist Medial torn more often, then lateralStoller, D. Pocket Radiologist
100Vertical Longitudinal Tears Most frequent,Medial 2.5:1 greater incidence than lateral meniscusperipheral tearGreater than 1 cm in lengthUnstable with stressCauses symptomsTreat with surgeryshort, less than 5mm, full thickness to partial thicknessstable, rarely cause symptoms, no surgery
101Meniscal Tears: Longitudinal Tears Axial illustration of a full-thickness longitudinal tear of the posterior horn.The meniscus is viewed from above in (a), sagittal in (b), and coronal in (c).A = anterior, L = lateral, M = medial, and P = posterior.Bowtie will be black in later veiw.
102Longitudinal Tear of the Meniscus Coronal T2 image (with fat suppression) shows a displaced fragment (arrow) of medial meniscus into the intercondylar notch of the knee.Also known as a bucket handle tearshare?id= %253APhoto%253A28117
103Vertical Transverse tears Radial tears, less common, almost always the middle third of the lateral meniscusStable less than 5 mmSurgery if it causes symptoms
104Radial TearAxial illustration of a full-thickness radial tear of the posterior horn.The meniscus is viewed from above.
105Degenerative tears Horizontal cleavage or flap tear. Increase incidence in age over 40,No specific injury or minor degree of stress can cause the tear.Can occur in either meniscus, associated with degeneration of the articular cartilageAfter age 40, will often have a horizontal splitting as a result of bending, squatting, turning and twisting over the years.Horizontal lesion seen in people over age of 55, not always symptomatic.More common in the medial meniscus, usually occurs at the junction of the middle and posterior one-third
106Horizontal Tear of Posterior Horn Axial illustration of a full-thickness horizontal tear of the posterior horn. The meniscus is viewed from above.Not the same as the radial tear, goes through the substance of the meniscus in a horizontal, not vertical line
107Posterior Horn Tear: Horizontal Fat-suppressed proton density-weighted sagittal images reveal a horizontal tear of the posterior horn of the medial meniscus (arrows), extending to the tibial surface.See the Bowtie, with a white slip indicating a tear.
108Flap tearAxial illustration of an oblique (parrot beak) tear of the posterior horn.The meniscus is viewed from above.In B, image 1 is most lateral, image 2 is middle, and image 3 is most medial.In C, image 1 is most anterior, image 2 is middle, and image 3 is most posterior.
110SX and Signs Signs: Change in WB status Minimal swelling may be noted with girth measurementsMcMurray's or Apley's test are positiveSpringy end feelSX:Pain at time of injuryPersists and interferes with WB activityRecurrent episodes with minor stressBaker's cystKnee is giving way
111RX: surgery Link between an absent meniscus and OA. Indications for surgery:Vertical tearsTears near the periphery of the meniscal substanceGenerally intact meniscal bodyTotal tissue defect less than 2 cm
112Synovial PlicaRemnant of 3 embryonic pouches of synovial membrane which remain in the knee as excessive synovial material. Medial plica is the most symptomatic . Will tighten during knee flexion and cause a change in the normal mechanics of the patellofemoral joint.
113Example: like a fine lace curtain Probably causes no symptoms,Although the elastic edge may bow-string over the bone of the femur when the leg bends and straightensShould there be an injury affecting the plica, however, the edge can thicken and then cause regular symptoms of a 'catching' pain at particular joint positions.
115SX and Signs: Sx: Similar to patellofemoral pain syndromes. Pain in the medial aspect of the knee jointClickingIntermittent locking sensation on medial sideGeneralized weaknessReports of joint instabilityClassic symptom is an inability to sit for prolonged periods of timeSigns: must rule out meniscus and ligamentous injuries, bone injuries, radiographs, MRI, CT scans
116RX Conservative treatment with NSAIDS Modalities Exercise May use transverse friction massage
117BursitisPrepatellar Bursitis: injury through direct trauma or chronic irritation such as prolonged kneeling.
118SX and Signs SX: Signs: Localized pain and swelling in the bursa Tenderness to palpationSigns:Swelling of the bursaWarm to touchRednessSlight loss of knee flexionStrong but painful resisted knee extension
119RX: Pain and edema control Anti-inflammatories Modalities in treatment May inject corticosteroids or drain bursa
120Bakers Cyst:Definition: any form of synovial herniation or bursitis involving the posterior aspect of the knee. Often occurs in conjunction with an intra-articular derangement at the knee such as a meniscal tear or ACL injury a. SX: mass behind the knee that may or may not be tender b. Signs: well defined, edematous mass on the posterior aspect of the knee c. When present, must rule out an internal derangement.
121Images of Baker’s Cystwww3.americanradiology.com
122Pes Anserine BursitisDefinition: follows a traumatic injury or unaccustomed WB exerciseSX: Medial knee painAching at restSwelling may be present on medial aspect of kneeSigns:Tenderness to palpationPain with resisted flexion
123Common Imaging Anteroposterior View Lateral View Sunrise View of the PatellaTunnel View of the KneeMRIMeniscus ImagingACL ImagingPCL Imaging
124RADIOGRAPHIC EXAMINATION OF THE KNEE AND PATELLA Anteroposterior view: Important to do weight bearing if possible. Either way, you should note if the x-rays were taken in standing or while lying supine.
125Alignment: Identify the following structures distal femurmedial and lateral condylesthe proximal tibiafibulathe patella superimposed over the distal femur
126Look at joint space for the tibia and femur, well defined in both medial and lateral views
127Normal knee: slight valgus alignment Medial and lateral joint spaces should be equalFemoral condyles should be aligned with the tibial plateausIncrease in valgus or a varus mal-alignment will increase stress on medial or lateral compartment, resulting in sclerosing of the femoral condyle and tibial plateau
128Anteroposterior view: 1One of these is WB and one is N WB – how can you tell? Look at the medial joint line on right leg especially2
129AP: Bone DensityAbnormal bone density: may see Osteochondral defects (OCD) on medial or lateral condyles of the femurBlue arrow points to a radioluscent cresent area on the knee: osteochondral dissecans
130Cartilage Clear, wide joint space Abnormal for there to be diminished spaceGenerally, one condyle is involved first, then both in advanced stages of OABone on bone – absence of meniscus
131Lateral View:Views the patellofemoral joint in profile, knee is flexed anywhere's from 20 dg to 45 dg and the beam is directed from a medial to lateral direction.
132Look for the relationship of the patella to the femur, can determine patella alta or patella baja
133Insall-Salvati Index: PLR = PL/TL The length of the patella ligament is measured from its attachment at the patellar apex to the tibial tuberosity (TL) and should equal the length of the patella (PL) from the superior to the inferior poles.Variance greater than 20% indicates an abnormal patella position.
134Lateral: Bone DensityIncrease in density as the condyles are superimposed on each otherMedial condyle is larger and extends distally further than the lateral condylePatella should be consistent in density
135Sunrise View or Skyline View Patella appears to be the sun, rising over the horizon Axial view of the Patellofemoral joint: Gives the articular surfaces of the patella and femur. Medial and lateral facets of the patella are visible Alignment of the patella in relation to the femur – lateral, medial etc.
136Note the sulcus angle of the femur: normal value of 138 degrees +/- 6 degreesshallow sulcus angles (greater degree within the angle) have been associated with recurrent patellar dislocations.
137Note the congruence angle which helps to define the position of the patella within the inercondylar sulcus.Normal value is -6 degrees.Congruence value of +16 has been associated with lateral patellar subluxation
138To measure the congruence angle: Find the highest point of the medial (B)and lateral (C) condyle and the lowest point of the intercondylar sulcus (A)The angle BAC, is the sulcus angle. Bisect the sulcus angle to establish the zero reference line, AO.Find the lowest point on the articular edge of the patella (D)Project line AD.The angle DAO is the congruence angle.All values medial to the zero reference line AO are designated as minus and those lateral as plus. Mean= -6 Degrees, standard deviation = 11 degrees.
139Other Common Views:Axial or Tunnel view of Intracondylar fossa: Taken in a prone position, will view the intercondylar fossa, and the posterior aspects of the knee joint.x-ray beam is projected in a posterior to anterior direction1,2 are intercondylar eminences3,4 are tibial plateaus
140MRIKnee joint MRI is one of the most frequently requested imaging study in musculoskeletal radiologyComprehensive, non-invasive view of the meniscus, ACL, PCL, medial and lateral collateral ligamentsSensitivity and Specificity of 90-95% for the meniscus and almost 100% for the cruciate ligaments. (Helms, 2009)
141Images Sagittal Sequences give the most information on the knee Short TE will help with imaging the meniscusFast Spin Echo – proton density (FSE-PD) do not produce acceptable images of the kneeFat suppressionMakes the MRI image easier to viewAllows the Meniscal tears to stand out easier than without the suppression.
142MRI Ligaments and Meniscus: image black whether it’s a T1 or T2 image. This MRI shows the meniscus as to triangular black blocks just under the femur.The patella ligament (tendon) images black from patella to tibial tubercle.
143MeniscusA fat-suppressed proton density-weighted axial image through the kneeDemonstrates the C-shaped menisci.Note the symmetrical shape of the lateral meniscus (red outline) and the asymmetry of the medial meniscus (blue outline), where the posterior horn (asterisk) is significantly larger than the anterior horn.
144Sagittal fat-saturated proton density–weighted image: Concave superior meniscal surface (arrows), which improves contact with the femoral epicondyles, and a flat undersurface, which improves contact with the tibial plateau.The periphery (outer edges) is thicker than the central portion (arrowhead), allowing for firm attachment to the joint capsule.Normal bow-tie appearance of the meniscal body.
145Coronal fat-saturated proton density–weighted image: Posterior slice Posterior horns of the medial and lateral menisci. The posterior horn of the medial meniscus (left arrow) is thicker than the posterior horn of the lateral meniscus (right arrow).The medial portion of the posterior horn of the lateral meniscus (ie, the meniscus on top of the fibula) is directed upward obliquely, from a lateral to medial direction. This is its normal course.
146Transverse (Intermeniscal) Ligament Axial fat-saturated proton density–weighted imageTransverse (intermeniscal) ligament (arrows) connecting the anterior portions of the medial and lateral menisci
147The ligament of Wrisberg Coronal proton density–weighted imageoriginating from the posterior medial horn of the medial meniscus and passing obliquely upwards (arrow) to attach to the posterolateral aspect of the medial femoral epicondyle
148Coronal fat-saturated proton density–weighted image of the mid knee Normal appearance of the body of the medial and lateral menisci.The apices (inner portions) are the thinnest part of the meniscus and are more central in the knee joint.The periphery, meniscal bases, outer portion (arrow and arrowhead) is the thickest part and contains the blood vessels supplying the meniscus.
149ACL and PCL: Normal Again, the ligaments will Image darker on the MRI. Note the orientation of fibersWhen determining theStructureThese two images are takenAt different depths in orderTo see the ligaments thisclearly