The five most common knee problems are arthritis, tendonitis, bruises, cartilage tears, and damaged ligaments. Knee injuries can be caused by accidents, impact, sudden or awkward movements, and gradual wear and tear of the knee joint.

3. Gross Anatomy: Bones
patellar surface
intercondylar eminence

4. Gross Anatomy: Skeletal Structure
22

5. Gross Anatomy: Articular Surfaces

6. Gross Anatomy: Menisci
 Fibrocartilaginous structures
Attach to tibia in intercondylar region
Transverse ligament connects the
anterior horns of each menisci
Vascular periphery (2-3 mm)
Medial meniscus
Oval-shaped
Attached to MCL
Thinner , less mobile
Lateral meniscus
Circular
Thicker, more mobile

7. Gross Anatomy: Synovial Membrane
MM
PCL
ACL
LM
Does not invest cruciate ligaments!
Bursae:
•Suprapatellar
•Subpopliteal
•Prepatellar
•Subcutaneous
infrapatellar
•Deep infrapatellar

8. Gross Anatomy: Ligaments
 Medial Collateral (MCL)
 Lateral Collateral (LCL)
 Anterior Cruciate (ACL)
 Posterior Cruciate (PCL)
 Meniscofemoral (MFL) Meniscofemoral
ligament

9. Gross Anatomy: Muscles
 Thigh
 Quadriceps femoris – VL, VM, VI, RF
 Sartorius
 Gracilis
 Hamstrings – BF, SM, ST
 IT band – GM, TFL
 Leg
 Gastrocnemius
 Plantaris
 Popliteus
(Pes anserinus)

10. Gross Anatomy: Popliteal Fossa
1. Semitendinosus
2. Biceps femoris
3. Semimembranosus
4. Sciatic nerve
5. Popliteal vein
6. Popliteal artery
Tibial n. Common
peroneal n.

11. Gross Anatomy: Vasculature
 Patellar Plexus
 Anastomoses of descending
branch of lateral circumflex
femoral a., anterior tibial
recurrent a., and genicular
branches
 Popliteal Artery
 Med./Lat. Superior Genicular
 Middle Genicular – enters capsule post.
to supply ligaments and synovium
 Med./Lat. Inferior Genicular
 Circumflex Fibular

12. Gross Anatomy: Nerve Supply
 Sciatic nerve
 Tibial n.
 Common
peroneal n.
 Wraps around
head of fibula
 Saphenous
branches
 Run deep to pes
anserinus

13. Patellar Dislocation
 Predisposition
 Genu valgum
 Overweight
 Patellar hypermobility
 Weak quadriceps
 Mechanisms
 Direct contact to
medial side
 External tibial rotation
with forceful
quadriceps contraction

14. Patellar Dislocation
 Vastus medialis
strain
 Tearing of medial
patellar
retinaculum
 Hemarthrosis
 Reduces with
extension

15. Patellar Dislocation: Diagnosis
 Obvious if not yet
reduced
 Patellar hypermobility/
apprehension test
 X-ray/MRI only
necessary to rule out
osteochondral fractures,
other associated injuries

16. Patellar Dislocation: Treatment
 Knee extension
 Aspiration to relieve
discomfort and check for
fat in blood
 Surgery unnecessary
unless osteochondral
fracture or complete
rupture of MPFL
 Crutches, PRICES
 Rehabilitation focusing
on vastus medialis

17. Meniscal Tears
 Shear force from femur
 Acute or degenerative
 Athletes, elderly,
overweight
 Vascular zone?
 Horizontal
 Within substance
 Longitudinal
 Bucket handle – ACL risk
 Radial or vertical
 Parrots beak

18. Medial Meniscus Tear
 Tears easier than lateral
due to certain traits
 Squatting
 Internal rotation of tibia
with knee flexed
 Member of “unhappy triad”
 Medial meniscus
 MCL
 ACL

19. Medial Meniscus: Diagnosis
 MRI
 Low-signal intensity
(black triangle ) =
normal
 White interruption =
lesion
 Arthroscopy as last
resort

20. Lateral Meniscus Tear
 Lower incidence
 Often more painful
 More likely to incur
radial or parrots beak
 Not rare for anterior
horn
 Discoid meniscus
 Wrisberg variety
 Congenital (1.5-3%)
 MM only 0.1 – 0.3%
femur
Discoid
meniscus

21. MCL: Diagnosis: Examination
 Abduction stress test
 First at 30
 Again at full extension
 Rule out PCL tear
 Anterior drawer test with
external rotation of tibia
 Hip flexed 45
 Knee flexed 90
 Tibia rotated 30 ext.
 Anterior rotation of
medial tibial condyle

22. MCL: Diagnosis: Imaging
 X-ray
 Only useful for young
patients to differentiate
from epiphyseal fracture
 Taken at 20-30 flexion
 Enlarged joint space = tear
 MRI
 Coronal scan
 Normal MCL looks thin,
taut, low-signal
 Grade I: indistinct MCL
(edema)
 Grade II: thicker, looser
 Grade III: severe edema

23. MCL: Treatment
 Surgery necessary for
compound injury
 Crutches + PRICES +
rehab for Grade I, II
only if isolated
 Grade III tears may
require surgical repair,
but immobilization can
be effective if isolated
(rare)
 3-4 months recovery
 Surgery
 Open incision
 Midsubstance ruptures
sutured
 Tear from bone repaired
with suture anchors

24. Lateral Collateral Ligament
 Courses slightly posterior
 Sprained least frequently
 Adduction force rare
 BF, popliteus, IT tract
 Flexed knee = isolated tear
 Anteromedial blow 
hyperextension/ postero-lateral
corner injury
 Risk to common peroneal
nerve
 Foot drop, sensation loss

25. LCL: Diagnosis: Examination
 Adduction stress test
 At 30, then full extension
 Ext. rotation recurvatum
 Lift legs by great toes
 Recurvatum + ext rotation +
varus = PL corner injury
 Posterolateral drawer test
 Tibia externally rotated,
posterior force applied
 Reverse pivot shift test
 Knee 90, tibia ext. rotated
 With valgus, slowly extended
 Temporary posterior
subluxation of lateral tibial
condyle around 30
 Forcibly reduces with extension

26. LCL: Imaging and Treatment
 MRI
 Coronal oblique scan
 Sagittal scan to rule
out fibular fracture,
avulsion
 Tear looks less taut or
discontinuous – no
thickening
 Treatment
 Similar to MCL
 Grade III usually
requires surgery

27. Anterior Cruciate Ligament
 Most common knee injury
among athletes
 AM fibers taut in flexion
 Check anterior displacement
 PL fibers taut in extension
 Check rotation
 Hyperextension, internal
rotation – rarely isolated
injury from contact force
 “unhappy triad”
 May tear from tibia (3-10%),
from femur (7-20%), or in
midportion (70%)
 Proximal end receives branch
from middle genicular a.
Internal rotation of right knee
(LEFT KNEE)

28. ACL: Diagnosis: Examination
 History, large hemarthrosis
 Autonomic symptoms
 Anterior drawer test
 Tibia neutral, pull ant.
 NOT RELIABLE BY ITSELF
 Lachman test
 Knee only flexed 15-20
 Pivot shift/jerk test
 Start in extension, tibia
internally rotated, valgus
 Slowly flex, lateral tibial
condyle temporarily
subluxates anteriorly ~30
 Reduces with further ext.
 Jerk test opposite (90 o)

29. ACL: Diagnosis: Imaging
 X-ray
 Segond fracture of
lateral tibial condyle
 ACL tear with it 75-
100%
 Tibial spine avulsion
in young patients
 MRI – 95% accuracy
 All 3 planes in full
extension
 Edema/hemorrhage
often obscures ACL
Normal ACL Torn ACL

30. ACL: Treatment
 Extrasynovial, heals
poorly
 Partial, isolated tears
may be treated with
PRICES, rehab, bracing
of slightly flexed knee
 Most tears, athletes will
require reconstruction

31. Posterior Cruciate Ligament
 Broader, longer, stronger
 PM and AL fiber bundles
 Receives better vasc. from
MGA, synovial membrane
 Checks post. displacement
 Tears much less frequently
 Only in isolation when
“dashboard knee” injury
 Hyperextension in sports,
especially with side force
 Falling to ground with
foot plantar flexed
Posterior view
Anterior view
Medial
femoral
condyle

32. PCL: Diagnosis
 Posterior drawer test
 Neutral start vital!
 Gravity or sag test
 Hips at 45 or 90,
compare tibial
tuberosities for sag
 Abduction/adduction stress
test at full extension
 X-ray to confirm sag test
 MRI shows lower-signal
intensity for intact PCL
compared to ACL due to its
fiber organization
 Take on all 3 axes, but best
is sagittal oblique
negative positive

33. Cruciate Ligament Reconstruction
 Complete excision followed
by graft insertion
 Allograft
 Autograft
 Patellar, quadriceps,
hamstrings, calcaneus
tendons used
 Undergoes biological
modifications: inflamed,
necrotic 
revascularization 
extrinsic fibroblasts
repopulate

34. ACL Reconstruction
 Autografts
 B-PT-B
 Quadruple hamstrings
 Semitendinosus, gracilis
 Only replace AM
 Double-Bundle
 Provides rotational
stability
 BTB as AM bundle
 Fixed at 20
 ST as PL bundle
 Fixed at 90

35. PCL Reconstruction
 Usually allograft –
calcaneus tendon
 Incorporates well
with long-term
stability
 BTB and ST often too
short
 Can achieve full
function with
reconstruction of just
AL bundle
A B
A. Low-power view cross section of PCL 11 years after
calcaneus tendon graft. B. High-power

36. Future of Reconstruction
 Goals:
 Improve recovery time
 Improve remodeling of insertion sites
 Improve nervous and vascular restoration
 With biological manufacture of:
 Growth factors, cytokines
 Antibiotics
 Techniques:
 Gene therapy – viral/non-viral vector delivers specific gene
 Tissue engineering – mesenchymal stem cells