Knee lesions Flashcards
articular defects osteonecrosis of the knee spontaneous osteonecrosis of the knee Pilcae
1
Q
What is the role of articulating cartilage?
A
- Covers articulating surfaces within joints
- functions include load transmission, lubrication and joint congruity
2
Q
Describe the classification of articular cartilage damage on arthroscopy?
A
- 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
3
Q
What is the presentation of articular cartilage defects of the knee?
A
- Localised pain, effusion, mechanical symptoms
- joint effusion, focal tenderness
4
Q
What is seen on imaging of carticular cartilage defects of the knee?
A
- Xray
- WB at 45o most sensitive for joint space narrowing
- alignment
- MRI most sensitive for focal defects
- CT- evaluate bone loss
5
Q
What is the tx of articular cartilage defects of the knee?
A
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
6
Q
describe the technique of debridment/chondroplasty?
A
- 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
7
Q
Describe the technique for fixation of unstable fragments?
A
- 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
8
Q
Describe the technique for marrow stimulation?
A
- 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
9
Q
Describe the technique for osteochondral autograft/mosaicplasty?
A
- 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
10
Q
Dsecribe the technique of osteochondral allograft transplantation?
A
- 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
11
Q
Describe the technique of autologous chondrocyte implantation (ACI)?
A
- 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
12
Q
Describe the technique of matrix- associated autologous chondrocyte implantation ( MACI)?
A
- 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
13
Q
What techniques are available for patella artcular defects?
A
-
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
14
Q
Describe the epidemiology of ostonecrosis of the knee?
A
- 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
15
Q
What are the risk factors for developing osteonecrosis of the knee?
A
- 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
17
Q
what is seen on imaging of ON of knee?
A
- Xray
- wedge shaped lesion
- MRI
- most sensitive
- T1: dark, T2 bright marrow oedema
21
Q
Describe the presentation of spontaneous ON of the knee?
A
- 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
