Lower Limb Injuries😊

Bakers cyst/Popliteal cyst

Sciatic nerve (L4–S3)

• Exits via greater sciatic foramen below piriformis

• No gluteal supply

• Bifurcates into Tibial and Common peroneal nerves in popliteal fossa

• IM injections in upper outer quadrant avoid it

Muscle innervation :

• Hamstring group
• Supplied by tibial component
• Semitendinous
• Semimembranosus
• Long head of biceps femoris
• Adductor Magnus (hamstring part)

• NOTE: Short head of biceps femoris:
• Not a hamstring, supplied by common peroneal nerve

Course :

• Sciatic Nerve → passes deep to pyriformis → Sometimes it pierces pyriform muscles and get compressed between them → resulting in pyriformis syndrome

• Sciatic nerve then divides into 2 components at popliteal fossa:
• Tibial component.
• Common peroneal component.

Tibial Nerve (TN)

• Supplies Plantar flexors (Posterior compartment)
• Also include Tibialis Posterior which is a plantar flexor as well as Invertor

• Cutaneous:
• Sural nerve → Lateral foot
• Medial calcaneal nerves → Heel
• Then ends as MPN and LPN at ankle
• Supplies the sole of the foot

Common Peroneal Nerve (CPN)

• Winds around neck of fibula (⚠️ common site of injury)

• Divides into:



• Superficial Peroneal Nerve (SPN)
• Supplies Evertors (Lateral compartment)
• Peroneus Longus
• Peroneus Brevis
• Sensory: Skin over majority of dorsum of foot.
• Deep Peroneal Nerve (DPN)
• Supplies dorsiflexors (Anterior compartment)
• Also include Tibialis Anterior which is a dorsiflexor as well as Invertor
• Sensory: Skin over 1st web space.

Nerve Injuries

Deformity Type	Description	Primary Nerve at Risk	Relative Risk during Total Knee Arthroplasty
Valgus	Knock-knee	Common Peroneal Nerve	Higher
Varus	Bow-legged	Tibial Nerve	Lower

Tibial Nerve Injury

• Plantar flexors and major invertors (T Posterior) get paralyzed.

• Leads to a condition called dorsiflexed & everted foot.

• Also known as calcaneovalgus → Calcaneal gait

• ↓ Ankle jerk

• ”Mneumonic: Door (dorsiflexion) End (Eversion) vann Tibia (Tibial N) yil idichapo Kalu Vedana (calcaneovalgal) ayi“

Common Peroneal Nerve Injury

• Innervation point: At neck of fibula.

Causes of injury:

• Neck of fibula fracture.

• Lateral condyle of tibia fracture / Bumper fracture.
• Axial loading + Valgus force

Manifestations:

• Dorsiflexors and Evertors are affected.

• Leads to:
• Foot drop:
• Foot cannot lift upward.
• Inverted foot:
• Foot turns inward
• Equinovarus position
• High Stepping gait/foot-drop gait/steppage gait
• to overcome dragging of foot due to foot drop

Treatment: 

• Foot drop/Toe-raising splint/Ankle-foot orthosis.

Foot nerves

• Medial plantar nerve (L4, L5)
• Motor: Abductor hallucis, FDB, 1st lumbrical, medial half of FHB
• Sensory: Medial 3.5 toes (plantar)
• Similar to median nerve

• Lateral plantar nerve (S1, S2)
• Motor: All other intrinsic muscles
• Includes: Adductor hallucis, 2–4 lumbricals, Interossei
• Sensory: Lateral 1.5 toes (plantar)
• Similar to ulnar nerve

• Adductors, Interossei, Bipinnate muscles → Supplied by lateral plantar nerve

SPORTS INJURIES

Anatomy Of Knee Joint

Soft tissue structures

• Extracapsular
• Collaterals:
• Medial collateral ligament (MCL)
• Lateral collateral ligament (LCL)

• Intracapsular
• Intrasynovial
• Menisci:
• Medial meniscus (mm)
• Lateral meniscus (LM)
• Extrasynovial
• Cruciate:
• Anterior cruciate ligament (ACL)
• Posterior cruciate ligament (PCL)

Key Anatomical Relations

• MCL: Adherent to medial meniscus (mm).

• LCL: Not adherent to lateral meniscus (LM).

Injury To Collateral Ligaments

Function of Collaterals

• Provide coronal plane stability to the knee.

Clinical Features

• MCL tear:
• Caused by forceful valgus stress test.
• Results in medial-sided knee pain.
• Diagnosed with an Abduction/Valgus stress test at 30° flexion.

• LCL tear:
• Caused by forceful varus stress test.
• Results in lateral-sided knee pain.
• Diagnosed with an Adduction/Varus stress test at 30° flexion.

• Incidence: 
• MCL > LCL

• MRI (Coronal view): 
• IOC
• May show edema due to MCL tear.

Management

• Conservative brace: Used in 90% of cases.

• Surgery: Required in 10% of cases.

Injury To Menisci

Functions Of Menisci

• Shock absorbers for the knee joint.

• Rotational stabilizers of the knee.

Forces & Types of Injury

• Torsion or forceful twisting of the knee
• when knee in flexed and fixed to ground

• Bucket handle tear: 



• Most common type of meniscal injury.

• MM > LM

Clinical Features

• Delayed onset of symptoms.

• Knee pain.

• Swelling: 
• Presents as mild to moderate effusion.

• Pathological locking of knee
• Incomplete extension
• Due to trapping of a fragment of meniscus
• between the tibial and femoral condyles.

Evaluation

• Thessaly

• Joint line tenderness: 
• Best test for meniscal injury.

• McMurray's test: 



• Involves
• hyperflexion of the knee,
• rotation with force, and
• extension, which provokes pain.

• Apley's grinding test: 



• Performed with the patient in a prone position,
• grinding the knee at 90° flexion.

Investigations

• MRI (Sagittal view): 
• IOC
• Heterogenous appearance
• in posterior horn meniscal tear

• Arthroscopy: 
• Gold standard for diagnosis and treatment of meniscal tears.

Treatment

• Meniscorrhaphy: 
• Surgical repair for Red zone tears,

• Meniscectomy: 
• Surgical removal for White zone tears,

NOTE

• Red Zone: 
• Good blood supply.
• from genicular vessels

• Red-White Zone: 
• Mixed blood supply.

• White Zone: 
• Poor blood supply.
• relying on synovial fluid

Injury To Cruciate Ligaments

• Posterior cord of ACL → Hyperextension unstable, Flexion stable

Function

• Provide sagittal plane stability to the knee.

Specific Ligaments and Their Role

• PCL (Posterior cruciate ligament) → Prevent Posterior displacement of tibia → Anterior displacement of femur

• ACL → Vice versa

Clinical Features

• Twisting injury to knee
• accompanied by hemarthrosis

• Instability on walking.

• Difficulty going
• downstairs → ACL tear
• Going anteriorly → munnott → downstairs
• upstairs → PCL tear
• Going posteriorly to home → upstairs

Evaluation

ACL injury tests:

1. Lachmann's test: 
• Most sensitive/best test.
• Performed at 20°-30° flexion of the knee,
• assessing anterior translation of the tibia.

2. Pivot shift test: 
1. Most specific test.

3. Anterior drawer test: 
• Painful in acute knee injuries.
• Performed with knee at 90° flexion and hip at 45° flexion,
• assessing anterior translation of the tibia.

PCL injury tests:

• Dial Test

• Posterior drawer test: 
• Performed with knee at 90° flexion,
• assessing posterior translation/sag of the tibia.

• Godfrey sag test: 
• Performed with hip and knee at 90° flexion,
• observing posterior translation due to gravity.

Mnemonic:

• Kurushinte (cruciate) frontl (ACL) Lakshmanan (Lachman) vara varachitt karangi (pivot) → posteriorly () god (godfrey) nilkkunnundarnnu watching his dial ()

Investigations

• MRI (Sagittal view): IOC

• Arthroscopy: 
• Gold standard for diagnosis and treatment.

Treatment

• Reconstruction with grafts, using
• gracilis
• semitendinosus tendons.

Summary of Structures in the Knee

O'Donoghue Triad of Knee

• Aka "unhappy" or "painful" triad, it involves:

• ACL tear

• MCL tear

• Medial meniscus (mm) injury

Segond Fracture

• Site: Avulsion fracture at lateral tibial condyle
• (near iliotibial tract / capsule).

• Associations:
• ACL injury
• MCL tear,
• medial meniscus tear,
• posterolateral corner injury

• MCL avulsion
• Pellagrini steida