Knee lesions

Question 1

What is the role of articulating cartilage?

Answer 1

• Covers articulating surfaces within joints
• functions include load transmission, lubrication and joint congruity

Question 2

Describe the classification of articular cartilage damage on arthroscopy?

Answer 2

• Outerbridge
• grade 0 = normal cartilage
• grade 1= softening and swelling
• grde 2= partial thickness defect, fissuring <1.5cm diam
• grade3= fissure down to subchondral bone, diam >1.5cm
• grade 4= exposed subchondral bone

Question 3

What is the presentation of articular cartilage defects of the knee?

Answer 3

• Localised pain, effusion, mechanical symptoms
• joint effusion, focal tenderness

Question 4

What is seen on imaging of carticular cartilage defects of the knee?

Answer 4

• Xray
  
  • WB at 45^o most sensitive for joint space narrowing
  • alignment
• MRI most sensitive for focal defects
• CT- evaluate bone loss

Question 5

What is the tx of articular cartilage defects of the knee?

Answer 5

Non operative

• rest, Nsaids, bracing
  
  • 1st line of tx
• Corticosteriods injections, hyaluronic acid, glucosamine
  
  • may provide symptomatic relief but healing unlikely

Operative

• Debridment/chondroplasty vs reconstruction techniques
• all individual decision made on pt age, skeletal maturity , low vs high activities, size of defect, location, contained vs uncontained or involvement of subchondral bone

Question 6

describe the technique of debridment/chondroplasty?

Answer 6

• goal is to debride loose flap of cartilage
• may relieve mechanical symptoms from loose chondral fragments
• short term benefit 50-70%
• simple arthroscopic proceedure, faster rehab

Question 7

Describe the technique for fixation of unstable fragments?

Answer 7

• need osteochondral fragment w adequate subchondral bone
• debride underlying nonviable tissue
• consider drilling subchondral bone or adding local bone graft
• fix with absorbable/ nonabsorbable screws
• best results for Osteochondritis dissecans in pts w open physis
• non absorbable screws should be removed at 3-6months

Question 8

Describe the technique for marrow stimulation?

Answer 8

• goal is to allow access of marrow elements into defect to stimulate the formation of reparative tissues
• Microfx
  
  • defect is prepared w stable vertical walls and calcified centre is removed
  • awls used to make punctate perforations thru the subchondral bone
  • protected weight bearing and continous passive motion used while mesenchymal cells mature into mainly fibrocartilage
  • cost-effectivenss,single stage, arthroscopic
  • best for acute, contained lesions 2x2cm​

Question 9

Describe the technique for osteochondral autograft/mosaicplasty?

Answer 9

• Goal is to replace cartilage defect in high wb area with normal autologous cartilage and bone plug from a lower wb area
• a recipient socket is drilled at site of defect
• Single or multiple small cylinders of normal articular cartilage with underlying bone are cored out from lesser WB area ( periphery of trochlea/notch)
• Plugs are then press-fit into defect
• limitations
  
  • size constraints and donor site morbidity limit uage of technique
  • matching size and radius if curvature of cartilage defect is difficult
  • fixation strength of graft initally decreases with inital healing response- NWB for 3/12
• Adv
  
  • single stage, cost effectivness, single stage, arthroscopically

Question 10

Dsecribe the technique of osteochondral allograft transplantation?

Answer 10

• Goal is to replace cartilage defect w live chondrocytes in mature matrix along with underlying bone
  
  • fresh, refriderated grafts are used which retain chondrocyte viability
  • may be preformed as a bulk graft ( fixed w screws) or shell ( dowels) graft
  • match the size & radius if curavture of articular cartilage with donor tissue
  • a recipient socket is drilled at site of the defect
  • an osteochondral dowel of approprate sie is cored out of donor
  • dowel is press fit into place
• adv
  
  • ability to address larger defects, can correct significant bone loss, useful in revision
• Dis
  
  • limited availiability & high cost of donor tissue
  • live allograft tissue potential infection risk

Question 11

Describe the technique of autologous chondrocyte implantation (ACI)?

Answer 11

• Cell therapy w goal of forming autologous “hyaline-like ‘ Cartilage
• arthroscopic harvest of cartilage from a lesser WB area
• in the lab chondrocytes are released from matrix and expanded in culture
• defect is prepared & chondrocytes are then injected under a periosteal patch sewn over a defect during a second surgery
• adv
  
  • ​may provide better histologic tissue than marrow stimulation
  • long term results comparable to microfx
• indications
  
  • must have full thickness cartilage at margins around defect
  • open surgery
  • 2 stage proceedure
  • prolonged protection necessary to allow maturation

Question 12

Describe the technique of matrix- associated autologous chondrocyte implantation ( MACI)?

Answer 12

• Cells are cultured and embedded in matrix or scaffold
• matrix is secured with fibrin glue or sutures
• adv
  
  • include ability to preform wihthout suturing
  • maybe preformed arthroscopically
• limited 2 stage proceedure

Question 13

What techniques are available for patella artcular defects?

Answer 13

• Maquet
  
  • tibial tubercle anteriorization
  • only for 1 distal pole lesion
  • only elevate 1cm
  • CI = superior patellar arthrosis
• Fulkerson alignment surgery
  
  • lateral and distal pole lesions
  • increased Q angle
  • CI= medial facet patellar arthrosis & medial femoral condyle, skeletal immaturuty

Question 14

Describe the epidemiology of ostonecrosis of the knee?

Answer 14

• 2 entities
• secondary osteonecrosis of the knee
• spontaneous osteonecrosis of the knee
• F>M 3:1
• Common women <55yrs
• location
  
  • typically involves > 1 compartment of knee
  • 80% bilateral
  • multifocal lesions are uncommon

Question 15

What are the risk factors for developing osteonecrosis of the knee?

Answer 15

• Etoh xs
• Dysbaric disorders- the bends
• Gaucher’s disease
• Sickle cell
• hypercoagulable states
• steriods
• SLE
• inflammatory bowel disease
• transplant pt
• virus- CMV, HIV, rubella
• protease inhibitors- HIV mediciation
• trauma

Question 16

What is the pathophysiology of ON of knee?

Answer 16

• appears to represent a subchondral insufficiency fx
• another hypothesis is assoc meniscal root tear

Question 17

what is seen on imaging of ON of knee?

Answer 17

• Xray
  
  • wedge shaped lesion
• MRI
  
  • most sensitive
  • T1: dark, T2 bright marrow oedema

Question 18

What is the usual presentation of pt wiht spontanoeous ON of knee?

Answer 18

• Pain with weightbearing especially sitting and standing

Question 19

What is the tx of ON of knee?

Answer 19

Non operative

• rest, limited wb, quads strengthening, activity modification

operative

• Diagnostic arthroscopy
  
  • remove small unstable fragments from joint
• Core decompression
  
  • extra-articular lesions
• Osteochondral allograft
  
  • large symptomatic lesions in young pts failed consx mx
• Total knee replacement
  
  • large area of involvment
  • collapse
  • Osteonecrosis in multiple compartments

Question 20

what is spontaneous ON of the knee?

Answer 20

• Osteonecrosis with no discernible aetiology
• most common middle age & elderly
• Females >55yrs
• location
  
  • 99% only 1 joint involved
  • usually epiphysis of Medial femoral condyle

Question 21

Describe the presentation of spontaneous ON of the knee?

Answer 21

• Sudden onset of knee pain
• effusion
• limited rom 2ary to pain
• tenderness over medial femoral condyle
• MRI most useful to determine extent of disease
  
  • lesion is Crescent shaped

Question 22

What is the tx of spontaneous osteonecrosis of the knee?

Answer 22

Non operative

• Nsaids, narcotics, protected WB
  
  • mainstay tx
  • physio- quds strengthening
  • inital consx shown good results

Surgery

• Arthroplasty
  
  • when symptoms fail consx tx
• High tibial osteotomy
  
  • when angular malaglinment present

Question 23

What is plicae syndrome?

Answer 23

• A painful impairment of knee function resulting from the thickened and inflamed synovial folds
• usually only medial plica
• 50% w hx of blunt trauma to anterior knee

Question 24

What are plica?

Answer 24

• Embryologic remnant synovial folds
• most common plicae =
  
  • Ligamentum mucosum
    
    • most common
    • located intercondylar notch
  • Suprapatellar plica
    
    • located in suprapatellar space, extending form medial wall of knee towards lateral wall
  • Medial Plica
    
    • extends from infrapatellar fat pad to medial wall of the knee
    • most commob irriated from abrading medial femoral condyle

Question 25

What is the presentation of plica syndrome?

Answer 25

• buckling
• snapping sensation
• pain w repetitive activity
• tenderness in medial parapatellar region
• painful, palpable medial parapatellar cord
  
  • can be rolled and popped beneath the examiners fingers

Question 26

What is the tx of plica syndrome?

Answer 26

Nonoperative

• rest, activity restriction, physio
  
  • most cases tx non operatively
  • physio
    
    • heat application
    • hamstring strengthening
    • resisted strengthening exercises are avoided in early rehab

Surgery

• Arthroscopic resection of lesion
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