Knee Flashcards
Stabilisers of the knee
o Strong capsule
o Intraarticular ligaments (ACL, PCL)
o Extraarticular ligaments (MCL, LCL)
o Muscles (quadriceps)
What is the Unhappy triad
- aka
- components
O’Donoghue triad
ACL + MCL + Medial Meniscus
How to tell between partial and complete tear of ligament
Grading of sprains
Partial: no abnormal mvt permitted, pain on attempted abnormal mvt
Complete: abnormal mvt permitted, little/no pain
Grade1: sprain - joint still stable - step off (<5mm translation) Grade2: partial tear (5-10mm) Grade3: complete tear (>10mm)
Mgx of ligamentous injuries
- aspirate hemearthrosis
- icepacks
- funcitional brace/ padded bandage (if avulsion #: plaster cylinder or if displaced: ORIF)
Conservative - physio: muscle strengthening (hamstring, quads)
SX: ligamentous reconstruction
Indications for ligamentous reconstruction
ACL tear in young person/ sportsman
ACL/PCL + collateral ligament injury
ACL reconstruction procedure (3Rs) and grafts
Grafts:
- hamstrings (semitendinosus), gracilis, patella tendon bone (autograft/ allograft)
Reattachment
Reinforcement
Replacement
ACL injury
- what # to look for
- attachments
- function
- MOI
- segond fracture
Attachments
- medial aspect of lateral femoral condyle and intercondyloid eminence of tibia
Function
- prevent anterior translation and internal rotation of tibia over femur
MOI
- int rotation on hyperextended knee
- varies blow to knee
Why ACL does not heal
- synovial fluid keeps 2 ends apart
- synovial fluid produces proteolytic enzymes which worsens damage
- synovial fluid prevents formation of a fibrin clot at wound site
Attachments of PCL
- Medial condyle of femur
- Posterior intercondylar area of tibia
Role of Menisci
o Increase stability of knee o Control complex rolling and gliding actions of joint o Distribute load during movement
Difference between medial and lateral meniscus
- why medial more easily injured
Medial: larger, kidney shaped
Medial affected more because
- Attached to MCL (less mobile)
- Absence of popliteus muscle insertions which can pull meniscus into more favorable position during sudden movements (as
with lateral meniscus)
Types of menisceal tears
- bucket handle tears (present with locking)
2. horizontal tears
Mgx of meniscus tear
preservation if possiblie 1. Arthroscopic surgery outer 3rd - attempt repair mid: intermediate inner 3rd: avascular and poor healing - total/ subtotal excision 2. post op physiotherapy
Classification of tibial plateau fractures
and management
Schatzker classification
if lateral condylar # only with no displacement/ depression<3mm: conservative (aspirate, immobilise)
all else, depression>3mm: ORIF
Types of patellar fractures and their management
- undisplaced: conservative - aspirate and plaster cylinder
- comminuted: backslab and early ROM else partial/ complete patellectomy
- transverse fracture with gap: internal fixation (tension band wiring and K wire) + plaster backslab
RF for recurrent patellar dislocation
o Generalised ligamentous laxity (marfan, down)
o Underdevelopment of lateral femoral condyle
o Maldevelopment of patella (too high or small or lateral)
o Abnormalities of lateral femoral condyle (flattening of intercondylar groove)
o Genu valgus (q angle)
o Tibial tubercle malalignment
o Primary muscle defect
o More common in girls
Mgx of recurrent patellar dislocations
Conservative:
- reduction, backslab
- physio: strengthen vests medialis
Sx:
- repair medial patellofemoral ligaments
- re-align extensor mech for more mechanically favourable angle of pull
- lateral release if lateral retinaculum too tight
RF for patella maltracking
- lateral patella tilt (malalignment of extensor mech/ vastus medialis weakness)
- tightness to lateral side (attach to ITB, lat retinaculum tighter than medial)
- weakness of VMO
- large Q angle
- valgus knee
- internal femoral torsion
- abnormal patella: high/ small
Causes of mechanical overload to patellofemoral joint
- malcongruence of patellofemoral surfaces
- malalignment of extensor mechanism or relative weakness of vastus medialis causing patella to tilt, bear more heavily on one facet (maltracking)
Q angle
- how to measure
- normal values
- what increases it
Q angle is the angle formed by a line drawn from the ASIS to the central patella and a
second line drawn from the central patella to the tibial tubercle.
Q angle is <18 deg for males and <22 deg for females with knee in full
extension.
<8 deg for males and <9 deg for females w knee in 90 deg extension.
Increased by:
- genu valgum
- increased femoral anteversion
- ext tibial torsion
- laterally positioned tibial tuberosity
- tight lateral retinaculum
- large pelvis
Differentials for anterior knee pain
- patella femoral overload
- patella tendinosis (jumper knee)
- patella subluxation
- osgood schlatters
- plica syndome
- hoffa syndrome
Mgx of patellofemoral overload
Conservative
- lifestyle
- physio: VMO
- analgesia
Sx
- arthroscopy lavage and shaving of fibrillated cartilage
- lateral release and patellar realignment
- drill exposed subchondral bone: revas to help repair fibrocartilage
- patellectomy
Osgood Schlatter disease
- x ray finding
- mgx
- any effusion?
X ray: displacement/ fragmentation of tibial apophysis
Mgx: spontaneous recovery
- apply ice
- analgesia
- rest, activity modification, restrict strenuous sports
- physiotherapy (quad)
- orthotic devices (knee brace)
no effusion - extra-articular
Causes of swelling in front of knee joint
- prepatellar bursitis (housemaid knee)
- infra patellar bursitis (clergyman knee)
Differentials for swelling at back of knee
Skin/ SQ: lipoma, sebaceous cyst
Artery: popliteal artery aneurysm
Vein: saphena varix @ saphenopopliteal junction, DVT
Nerve: Neuroma
Cyst: Baker (a/w degen changes), Popliteal
Differentials for swelling at back of knee
- Skin/ SQ: lipoma, sebaceous cyst
- Artery: popliteal artery aneurysm
- Vein: saphena varix @ saphenopopliteal junction, DVT
- Nerve: Neuroma
- Enlarged bursae: semimembranosus
- Cyst: Baker, Popliteal
Baker cyst
- what
- associations
- risk
- posterior herniation of knee joint capsule, leading to escape of synovial fluid into posterior bursa
- a/w degenerative charges: OA, RA, Charcot joint
- risk: increases risk of venous stasis/ DVT (compression of popliteal vein)
Differentials of swelling at side of knee joint
- meniscal cyst
- calcification of collateral ligament
- bony swelling (rule out tumor)
loose body in joint
- suggestive history
- causes
sudden locking
swollen joint
palpable LB
causes: injury, OA, synovial chondromatosis, Charcot joint
Causes of Charcot joint
DM, peripheral neuropathy, tertiary syphilis, tabes dorsalis, syringomyelia, myelomeningocele, cauda equina
Osteochondritis dissecans
- what is it
- mgx
What: AVN of fragment of subchondral bone predisposing overlying cartilage and subchondral bone itself to fragmentation
Early: conservative (lifestyle modification)
SX:
- arthroscopic removal of loose bodies
- if large fragment, insitu fixation with pins/ Herbert screws
- cartilage transplantation
Measuring for genu varum and valgus
genu varum: distance between knees with leg straight and medial malleoli just touching <6cm
genu valgum: distance between medial malleoli when knees touching <8cm
Causes of knee malalignments
- trauma to growth plate (growth arrest)
- infection
- tumor
- bone dysplasia
- rickets (vitD deficiency)
- Blount disease (infantile)
Blount disease
- what is it
- RF
- mgx
Idiopathic arrest of growth plate on medial side of tibia > progressive genu varum due to abnormal growth of posteromedial part of proximal tibia
RF:
- overweight children
- children walking early
- female
Mgx:
<3yo: circumferential brace
>3yo: high tibial osteotomy
Etiology of intoeing
- infant
- toddler
- child
Infant: metatarsus adducts
Toddler: medial tibial torsion (look for neg thigh foot angle) - normal:15deg
Child: medial femoral torsion - femoral anteversion
> history of W sitting
> mgx: cross legged sitting
Surgery for knee deformities
Young: epiphyseodesis - stapling one side of physics to slow growth on that side
Osteotomy:
- valgus: supracondylar femoral
- varus: high ribia
Joint reconstruction
Why consider hip causes in knee pain
referred pain: obturator nerve crosses both joints
Approach to knee pain
- Referred pain
- Generalised: OA, RA
- Localised:
> patellofemoral: patellar instability, PF overload, PFOA, osteoxchondral injury
> joint: osteochondritis dissecans, loosebody, ligament tear, meniscal tear
> periarticular: patellar tendinitis, ligament strain, bursitis, OSD
Causes of knee swelling
Traumatic - effusion/ hemarthrosis (lig injury) - traumatic reactive synovitis (meniscal) Non traumatic - septic/ crystal induced arthritis - seroneg arthritis (PAIR: psoriasis, AS, IBD, Reiter) - seropos arthritis (RA, SLE) - AVN - sickle cell dz - synovitis
Causes of knees giving way (instability)
- ligament: ACL, PCL, LCL, MCL
- recurrent dislocation of patellar/ subluxation
- torn meniscus, loose body
- OSD
- RA
- muscle weakness
