ACUTE KNEE INJURIES: MAKING THE DIAGNOSIS

Richard A. Lemon, M.D.
Orthopaedic Surgeon

Common Site of Injury in Many Recreational Sports

•	Skiing - 1/3 of all injuries
•	Basketball - 7:1; female:male
•	Soccer, Softball, Volleyball, Wrestling, Football

HISTORY

•	Mechanism of Injury
•	Valgus stress; Hyperextension; Direct blow; Twisting

•	Swelling
•	Acute: 
–	4-6 hours = hemarthrosis
•	>24 hours = effusion

PHYSICAL EXAMINATION 

•	Anatomy
•	Ligaments - ACL, PCL, MCL, LCL
•	Meniscus - medial, lateral
•	Tendon - quadriceps, patellar, medial retinaculum
•	Bone - femur, tibia, patella

•	Ligaments
•	ACL - Lachman, Anterior Drawer, Pivot Shift
•	PCL - Reverse Lachman, Posterior Drawer, Reverse Pivot
•	MCL - 0 and 30° (30° isolates MCL)
•	LCL -  0 and 30° (30° isolates MCL)

•	Meniscus
•	Joint line tenderness - 95%
•	Pain at limits of flexion - 65%
•	Pain at limits of extension - 40%
•	McMurray test - 33%

•	Tendons
•	Quadriceps - defect above patella
•	Patellar - high riding patella

DIAGNOSTIC STUDIES

•	X-rays - Four Views Always
•	AP
•	Lateral
•	Tunnel or notch
•	Patella - Sunrise, Merchant, Laurin, Hughston

•	MRI
•	Menisci, articular cartilage, effusion
•	ACL, PCL, MCL, LCL
•	Bony abnormalities - fractures, O.D.

•	SUMMARY

•	History
•	The patient will tell you what they injured.

•	Physical Exam
•	Hemarthrosis = ACL tear, unless proven otherwise
•	Relaxed patient = good exam
•	Examine all structures

•	Avoid
•	Aspiration
•	Prolonged use of knee immobilizer
•	Prolonged use of crutches

•	Encourage
•	Early motion
•	Referral to orthopaedics