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Acute Knee Injuries

Acute Knee Injuries

8/9/19

Acute Injuries

Scott D. McKay, MD Associate Professor Orthopaedic Texas Childen’s Hospital Baylor College of

Objectives

• Identify

• Recognize common mechanisms for acute knee injuries

– Mechanism can often tell you as much as the physical exam

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• 64% ACL or

• >40% had surgery for their injury

Outline

Recognize Knee Effusion Anterior Cruciate (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

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Outline

Recognize Knee Effusion Anterior Cruciate Ligament (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

Knee Effusion

• Abnormal fluid accumulation in a

• Normal outline of gone

• Most of fullness superior to patella

https://www.bjchealth.com.au/connected-care/the-most-common-cause-for-a-swollen-knee-in-a-young-woman

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Sagittal View

NOT Knee Effusion

Prepatellar bursitis

https://musculoskeletalkey.com/prepatellar-bursitis-housemaids- knee/

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Outline

Recognize Knee Effusion Anterior Cruciate Ligament (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

ACL Tears

• Most tears are “noncontact”

• More common in women

• 3 positions: – Slightly flexed (<30) – Twisting – Valgus

• Feel a POP

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Physical Exam

• Effusion +

• Lachman +

• Anterior Drawer +/-

• Pivot Shift

Lachman

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Anterior Drawer

Workup

• Exam is diagnostic • X-rays – Usually normal – Segond fractures • MRI – Look for associated injuries

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Treatment

• Recommend surgical treatment for cutting/pivoting athletes

• Return to sport 6-12 months – Criteria-driven – NOT merely time driven – Time to return is influenced by “prehab”

• High risk of re-injury: – 10-15% re-tear rate, and 10-15% contralateral tear rate

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Outline

Recognize Knee Effusion Anterior Cruciate Ligament (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

Patella Dislocation

• Underlying anatomic cause

• Often non-contact

• High rate of recurrence (70%)

https://www.orthobullets.com/knee- and-sports/3020/patellar-instability

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Mechanism

• Knee flexed

• Trunk rotation towards affected side • rotates inward • fixed

• Valgus Coviello M., Mazzola C. (2016) Management of the First • Quadriceps contraction Patellar Dislocation. In: Volpi P. (eds) Arthroscopy and Sport Injuries. Springer, Cham

S. Brent Brotzman, Chapter 56 Patellofemoral Disorders, Editor(s): Charles E. Giangarra, Robert C. Manske, Clinical Orthopaedic Rehabilitation: a Team Approach (Fourth Edition),2018, Pages 376-388.e1, ISBN 9780323393706,

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J-sign

• Video of J-sign

• https://casereports.bmj.co m/content/2018/bcr-2017- 222887

Risk Factors for Patellar Dislocation

• J-sign • Femoral anteversion • Increased Q-angle • • Lateral patellar tilt • Family history

• • Personal history on other side

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Presentation

• Usually already spontaneously reduced

• If still dislocated, straighten knee

• Large knee effusion, negative lachman

• Examine the other knee! – Valgus, j-sign

Imaging

XR: • Medial avulsion fractures common • Osteochondral loose bodies

MRI: • Typical bone bruise pattern • Find loose bodies

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Treatment (First Time)

• Supportive – RICE – Crutches as needed

• Patellar stabilizing brace

• Physical

• Return to sport 6-12 weeks

Surgical Treatment

• Recurrent dislocation interfering with desired activities

• Osteochondral loose bodies

• Surgical treatment addresses underlying anatomic abnormalities

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Outline

Recognize Knee Effusion Anterior Cruciate Ligament (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

Avulsion Fractures

• Ligamentous or tendinous avulsions

• Ligamentous avulsion mechanisms match ligament stress – Varus force = LCL tear or avulsion – Valgus force = MCL tear or avulsion

• Tendinous avulsions can happen with forceful contraction

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Tibial Tubercle Fracture (Patellar )

• Often have pre-existing pain

• Jumping mechanism most common

• Surgically treated

• Excellent result. Back to sport 3-6 months

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Fibular Avulsions • Biceps/LCL avulsion – High energy injury – Direct blow to anteromedial – Can have peroneal nerve injury

• Usually part of multiligamentous knee injury requiring complex reconstruction

ACL Avulsion

• Same ACL mechanism

• Ideally treated with early repair

• Excellent outcome

• Back to sports in 3-6 months

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PCL Avulsion

• Fall on a flexed knee

• Feel better quickly

• Not always treated surgically

• Good outcomes

• Popliteus tendon avulsions heal with supportive treatment • Return to sport in 6 weeks

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Outline

Recognize Knee Effusion Anterior Cruciate Ligament (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

Meniscus Tears

• C-shaped cartilage structures

• Distribute force throughout the knee

• Provide some rotational stability

https://www.health.harvard.edu/a_to_z/torn-meniscus-a- to-z

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Meniscus Tear Case – May 2019

• 17 yr old young woman

• Knee forcefully rotated while squatting in wrestling. Felt a pop. Swollen after the match

• Physical exam: – Effusion, medial joint line tenderness, pain with mcmurray’s.

MRI

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Management

• Chose a period of conservative treatment

• No improvement in pain, especially with hiking/running/trampolines

• Treated with arthroscopic repair 2 weeks ago

• Goal is Naval academy next summer? Wrestling this winter?

Meniscus Summary

• Generally rotation and flexion cause injury

• Effusion is present

• After acute phase, provocative tests reproduce flexion/rotation: – Mcmurray’s test – Thessaly test – Apley compression test

• Diagnosis is by MRI

• Treatment is usually surgical in children & adolescents

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Discoid Meniscus

• Instead of a “C” it’s a “Frisbee”

• Easily torn

• Can cause the entire knee to shift and clunk if unstable

• Treatment is surgical when symptoms warrant

Geffroy L., Bouguennec N. (2016) Meniscal Lesions in Children: Classification, Discoid Meniscus, Traumatic Lesions. In: Hulet C., Pereira H., Peretti G., Denti M. (eds) Surgery of the Meniscus. Springer, Berlin, Heidelberg

Outline

Recognize Knee Effusion Anterior Cruciate Ligament (ACL) Patellar Dislocation Avulsion Fractures Meniscus Tears Bone Bruising

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More Than Just Bumps & Bruises

Case • 16-yr-old young lady who got caught in a wave swimming in Mexico and somehow hit her legs on rocks & sand in May 2019 • Immediate diffuse pain & swelling • Persistent pain with weight bearing (medial proximal tibia) • Physical exam normal last week in my office • XR normal

MRI – Nondisplaced Fractures and Contusion

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Treatment – Bone Contusions

• Limited weight bearing for 4-8 weeks

• Excellent result

• Don’t need follow-up MRI...Signal takes a long time to resolve

Summary

• Identify effusion after injury – Important sign of significant injury

• Recognize common mechanisms for acute knee injuries: – ACL tears – Patellar dislocations – Avulsion fractures & – Meniscus tears – Bone bruising

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