This document provides an overview of common injuries around the knee joint. It describes the anatomy of the knee including bones and ligaments. Common mechanisms of injury are discussed for fractures around the knee like condylar fractures of the femur, patella fractures, and tibial plateau fractures. Injuries to the ligaments including ACL, PCL, MCL and LCL are also summarized. Treatment approaches for many of these injuries including nonsurgical and surgical options are highlighted. Other topics covered include meniscal injuries, knee dislocations, and patella dislocations. Complications of various knee injuries are also mentioned.

1. Injuries around the knee
Dr Siddhartha Sinha
Senior resident, Department of orthopaedics
Lady Hardinge Medical college

2. Anatomy
• Largest and most superficial joint
• Hinge joint
• Flexion and extension
• Tibia and femur (tibio-femoral). (weight bearing
part)
• Patella and femoral condyles (patellofemoral joint)
(directs the pull of the quadriceps anteriorly)
• Fibula NOT part of the joint
• Stability – ligaments
• Collateral ligaments- medial and lateral collateral
(Valgus and varus stablility)
• Cruciate ligaments- Anterior and posterior cruciate
ligament (AP stability)

3. • Menisci-
• Fibrocartilage
• Act as shock absorbers
• Medial meniscus- C shaped, broader
posteriorly than ant.
• Lateral meniscus- almost circular, freely
movable, smaller (less prone to injury)

4. • Movements around the knee
• Flexion-
• Primary: Hamstrings (semitendinosus,
semimembranosus, long head of biceps); short head of
biceps
• Secondary: Gracilis, sartorius, gastrocnemius, popliteus
• Extension
• Primary : Quadriceps femoris
• Secondary: TFL
• Some medial and lateral rotation
• Screw home mechanism:
• Knee passively “locks” because of medial rotation of
the femoral condyles on the tibial plateau
• Makes the lower limb a solid column and more
adapted for weight-bearing.
• When the knee is “locked,” the thigh and leg muscles
can relax briefly without making the knee joint too
unstable.
• To unlock the knee, the popliteus contracts, rotating
the femur laterally about 5° on the tibial plateau so
that flexion of the knee can occur

5. Mechanism of knee injuries
• Direct trauma
• Indirect trauma
• Valgus
• Varus
• Hyperextension
• Twisting

6. Condylar fractures of the femur
• 3 types
• Supracondylar fractures
• Unicondylar fractures – medial or
lateral. Hoffa # (frontal plane)
• Intercondylar fractures – T or Y
types
• Direct injury to distal femur
• Inter-condylar # patterns
• Indirect injury (valgus/ varus)
• Supracondylar
• Unicondylar patterns

8. • Diagnosis
• Pain
• Swelling
• Bruising around the
knee
• Difficulty walking
• Associated injuries
• Shaft of femur
• Tibia shaft
• Pelvis #
• X-ray
• Thigh with Knee –AP &
Lateral
• Thigh with hip- AP &
lateral

9. • Treatment
• Unicondylar fractures
• Undisplaced : long leg cast is given for 3-
6 weeks, followed by protected weight
bearing.
• Displaced: open reduction and internal
fixation
• cancellous screw or Herbert screws
• Buttress plate

10. • Intercondylar #
• Aim to restore articular congruity
and prevent knee stiffness
• ORIF with DCS/ Distal femoral
metaphyseal locking plate/ codylar
blade plate
• Conservative : rare using skeletal
traction

11. • Supracondylar fractures:
• Internal fixation. closed or
open techniques.
• Nail
• Antegrade or retrograde
• Plate
• Complications
• Knee stiffness- dense intra
and peri-articular adhesions
• Osteoarthritis-
malalignment of mechanical
axis or incorguent joint
surface causing change in
load bearing mechanics of
the knee
• Malunions- varus or valgus,
may require corrective
osteotomy

12. Patella #
• Largest sesamoid bone in the body.
• 7 articular facets; the lateral facet is the
largest (50% of the articular surface).
• Medial and lateral retinaculum
• Function
• Increase the mechanical advantage and
leverage of the quadriceps tendon
• Aid in nourishment of the femoral articular
surface,
• Protect the femoral condyles from direct
trauma.

13. Mechanism of injury
• Direct:
• Produce incomplete, simple, stellate, or
comminuted fracture patterns.
• Displacement minimal due to
preservation of the medial and lateral
retinacular expansions.
• Abrasions over the area or open injuries
are common.
• Active knee extension may be
preserved.

14. • Indirect (most common):
• Secondary to forcible quadriceps contraction while the
knee is in a semiflexed position (e.g., in a “stumble” or
“fall”).
• Intrinsic strength of the patella is exceeded by the pull of
the musculotendinous and ligamentous structures.
• Transverse fracture pattern is most commonly
• Degree of displacement of the fragments suggests the
degree of retinacular disruption.
• Active knee extension is usually lost.
• Combined direct/indirect mechanisms:
• Patient experiences direct and indirect trauma to the knee
(fall from a height)

15. Classification of patella #

16. Clinical features
• Pain and swelling over the knee.
• Undisplaced fracture : swelling and
tenderness may be localised over the patella.
• Crepitus (+)
• Displaced fractures : gap between the
fracture fragments.
• Extensor lag : loss of terminal 15-30 ° of
extension because of disruption of the
extensor apparatus.
• Bruises over knee

17. Radiological evaluation
• Antero-posterior view
• Lateral view
• Skyline view

18. Treatment
• Undisplaced
• Cylindrical cast (groin to just
above the malleolus) x 3 weeks
then physiotherapy
• 2 part fracture
• Tension band wiring:
• Allows early mobilization and
healing at # site
• Principle: when an eccentric load
is applied to tension band
construct the distractive forces (of
patella and quadriceps tendon)
are converted to compressive
forces leading to compression at #
site and healing

19. • Partial Patellectomy: part of
the patella is excised and
the extensor mechanism
repaired
• Total patellectomy: whole
patella is excised and
extensor mechanism
repaired
• Comminuted #
• Encirclage
• Partial patellectomy
• Total patellectomy
• Complications of patella #
• Knee stiffness
• Extensor mechanism
weakness
• Osteoartritis

20. Injuries of ligaments around the knee
• Common sporting injury, type of
injury depends upon the direction of
force and its severity.
• Mechanism of injury
• Medial collateral – Valgus
• Lateral collateral- Varus
• ACL –most commonly injured tendon,
twisting on a semi flexed knee
• O’ Donohuges triad- MCL , MM, ACL injury
• PCL –posterior force on a semi flexed
knee

21. Pathoanatomy
• Ligaments can tear on
either attachment or
through substance
(mid- substance tear)
• Avulsion #
• When a bony
fragment is avulsed
along with the
ligament

22. Diagnosis
• History
• h/o fall / sports injury leading to
pain swelling
• Sound of something tearing
• Swelling (haemarthrosis)
• Pain at site of torn ligament
(collateral injury)
• Vague pain (cruciate or meniscus
injury)
• Knee giving way, unable to run/
pivot

23. • Examination findings

24. • Valgus/Varus stress test for MCL and LCL in full extension and 30°
flexion
• Abnormal “opening up of the joint compared to normal side is positive)

25. • Cruciate ligaments
• Anterior cruciate
• Anterior drawer
• Knee at 90°, Hamstring relaxed
• Stabilize leg and foot
• Restore normal tibial step off
• Apply anterior directed force and
compare with the other side
• Can not be done in acute injury
• False negative due to doorstop effect of
meniscus
• Lachman
• Can be done in acute injury
• More sensitive than anterior drawer test
• Place knee in 30° flexion and apply
anterior force and assess end point
• Soft= injury
• Firm/ bony= no injury
• Pivot shift test

26. • Posterior cruciate
ligament
• Posterior drawer test
• Same perquisites as anterior
drawer but now direction of
force is posterior
• Posterior sag
• Dial test

27. • Radiological examination:
• Plain X-ray
• Normal usually or soft tissue swelling
• Chip of bone avulsed from the ligament attachment may be visible.
• Stress views in valgus/ varus: demonstrate an abnormal opening-up of the joint
• MRI is a non-invasive method of diagnosing ligament injuries, and may be of
use in doubtful cases.
• Segond fracture:
• Avulsion fracture of the proximal lateral tibia
• Pathognomonic for an ACL tear
• Represents bony avulsion by the anterolateral ligament (ALL)
• Associated with ACL tear 75-100% of the time
• Pellegrini-Steata lesion (calcification along the insertion of the medial
collateral ligament)
• Tibia Spine avulsion #
• ACL avulsion at tibial insertion
• Posterior cruciate ligament avulsion #
• Tibial insertion of PCL posteriorly

28. • Other tests
• MRI
• Diagnostic arthroscopy

29. • Treatment
• Immediate: RICE (REST , ICE, COMPRESSION,
ELEVATION) and analgesics
• Previously conservative management preferred due to
average results
• Operative treatment now preferred for patients with
instability and high daily demands like athletes
• Conservative Mx
• Cylindrical cast
• Appropriate for grade I or II
• Initiate physiotherapy after 2-3 weeks of immobilization in cast
• Surgical MX
• Performed 2-3 weeks after injury to allow soft tissue swelling to
subside and prevent knee stiffness
• Reconstruction of ligament using autograft or allograft (hamstring,
patella, TFL, peronei, quadriceps), synthetic materials
• Repair: not done now due to poor results

30. • Complications
• Knee instability
• Osteoarthritis

31. Tibial Plateau Fractures
• 1% of all fractures and 8% of fractures in
the elderly.
• Isolated lateral plateau account = 55% to
70%
• Isolated medial= 10% to 25% plateau
fractures
• Bicondylar lesions= 10% to 30%
• Open injuries= 1% to 3%
• Due to RTA

32. Mechanism of injury
• Varus or valgus forces
coupled with axial
loading causing a
series of disruptions as
the force keeps acting
on the knee

33. Classification
• Schatzker
• Hohl and Moore

34. • Clinical features
• Pain, swelling, deformity, inability to bear wt.
• Neurovascular examination
• Distal pulses of dorsalis pedis and posterior tibial- injury to popliteal
artery
• The peroneal nerve is tethered laterally as it courses around the
fibular neck.
• Hemarthrosis
• Compartment syndrome must be ruled out
• Assessment for ligament injury is essential. (but should be
done once pain has decreased)
• Associated injuries
• Meniscus
• Cruciate and collaterals
• Distal femur fractures

35. • Radiography
• Plain x rays
• CT scans
• MRI to evaluate soft
tissue and ligaments
• Arterial Doppler/
arteriogram for evaluation
of vascularity
• Treatment
• Non operative
• Undisplaced or minimally
displaced #
• Cast application followed
by hinge knee brace,
protected wt bearing for 8-
12 weeks and quadriceps
exercises

36. • Operative Mx
• Restore articular
congruency and
tibial alignment
• Choice of implant
related to fracture
patterns
• Plates, screws,
external fixator or
any combination
of these
• Assess for
ligamentous injury
and repair if
required

37. Complications
• Knee stiffness
• Infection
• Compartment syndrome
• Malunion or nonunion
• Posttraumatic osteoarthritis
• Peroneal nerve injury
• Popliteal artery laceration
• Avascular necrosis of small articular fragments

38. Meniscal injuries of the knee
• Mechanism
• Person standing on a semi-flexed knee, twists his body to
one side.
• During this movement the meniscus is 'sucked in' and
nipped as rotation occurs between the condyles of femur
and tibia.
• Medial meniscus gets torn more often because it is less
mobile (being fixed to the medial collateral ligament).
• Pathoanatomy
• Injured most commonly at its posterior horn.
• Subsequent injury, the tear extends anteriorly.
• Avascular structure, once torn does not heal.
• Periphery vascular- may heal, center avascular – does not
heal
• Untreated-more subtears- damages the articular
cartilage, - initiating osteoarthritis.

39. • Types of meniscal tear:
• Bucket handle most common type
• Meniscus more prone to injury in
• Discoid meniscus
• Degenerated meniscus
• Meniscal cyst

40. Clinical features
• History
• Young patient engaged in sports
• Recurrent episodes of pain and locking of the knee
• Sudden jerk while walking or clicking followed by
swelling
• h/o twisting injury followed by swelling appearing
overnight and once swelling subsides patient may not
be able to extend the knee fully d/t torn meniscus
• Ligament injury: immediate swelling, meniscus injury : late
swelling
• History of sudden locking and unlocking and click is
DIAGNOSTIC of meniscus injury

41. Examination of meniscus
• Tenderness in the region of the joint line
• Locked knee
• Attempts to force full extension produces a
sensation of elastic resistance and pain, localized
to the appropriate joint compartment
• Wasting of the quadriceps

42. • McMurray test
• Flex knee and IR to test for lateral meniscus
and extend
• Flex and ER to test for medial meniscus and
extend again
• Check for pain/ crepitus
• Apleys grinding test
• Distract knee to assess ligament injury
• Compress knee to assess meniscal injury
• Thessalays test
• Patient standing on affected limb with
support and asked to IR and ER lower limb
• Pain s/o injury

43. • Radiologial examination
• Xrays are normal
• MRI can detect tears non invasively and very sensitive
• Arthrography- injecting dye in joints – no longer used as MRI has high
sensitivity
• Diagnostic arthroscopy- invasive, direct visualization of the tear

44. Treatment
• Acute tear
• RICE + analgesics
• Locked knee: manipulation under
anaesthesia + immobilization x 2 weeks
then physiotherapy
• Chronic meniscal tear
• Partial menisectomy- remove the torn part
of the meniscus
• Repair- if tear in the vascular zone or
intermediate zone
• Total menisectomy- removal of whole
meniscus, rarely indicated, not preferred

45. Knee Dislocation
• Uncommon injury
• Significant soft tissue damage leads to loss of
all structural integrity of the knee causing
dislocation
• All ligaments around the knee injured
• Popliteal artery damage – watch patients for
upto 72 hours to check for late vascular
compromise
• Reduce and apply cylindrical slab x 2weeks
and observe for signs of vascular compromise
for upto 72 hrs

46. Extensor apparatus disruption
• Tearing of the quadriceps tendon from its attachment on the patella
• Tearing of the attachment of the patellar tendon from the tibial
tubercle.
• T/t: operative management

47. Patella dislocation
• Lateral dislocation common
• Types:
• Acute
• Recurrent
• Habitual
• Acute:
• Sudden contraction of the quadriceps while the
knee is flexed or semi-flexed.
• Patella dislocates laterally and lies on the outer
side of the knee.
• Unable to straighten knee
• Prominance of medial condyle of femur
• May reduce spontaneously
• T/t: reduction and immobilization in cylindrical
cast or knee immobilizer x 3 weeks
• If osteochondral injury or loose body- arthroscopic
debridement or removal

48. • Recurrent dislocation of the patella:
• Multiple and frequent episodes of dislocation after the first episode of
dislocation, more and more ease.
• Cause of recurrence
• Laxity of the medial capsule
• Defect in the anatomy of the knee.
• Excessive joint laxity
• Small patella
• Patella alta
• Genu valgum.
• Treatment
• Multiple procedures both bony and soft tissue
• Evaluate the cause of recurrence and treat

49. • Habitual dislocation of the patella:
• Patella dislocates laterally everytime the knee is flexed.
• Underlying defects are very similar to those in recurrent dislocation.
• Shortened quadriceps (vastus lateralis component) may result in an abnormal
lateral pull on the patella when the knee is flexed.
• Treatment :
• Release of the tight structures on the lateral side
• Repair of the lax structures on the medial side
• An additional ’checkrein’ mechanism of some sort is created to prevent re-dislocation.