Skip to content
mskultrasound banner 2

Knee: Normal And Pathology

Table of Contents show

Authors

Victor Huang, MD, CAQ-SM
Assistant Professor
Department of Emergency Medicine
New York Presbyterian Queens
Weill Cornell Medical College

William Denq, MD, CAQ-SM
Assistant Professor
Department of Emergency Medicine
University of Arizona

Editors

William Denq, MD, CAQ-SM
Assistant Professor
Department of Emergency Medicine
University of Arizona

Summary

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

knee extensor mechanism illustration and ultrasound
Anterior knee with schematic illustration (a) and corresponding sonographic view (b). Qt (quad tendon), Pt (Patella tendon).[1]Image courtesy of nysora.com, “Normal Ultrasound Findings and Scanning Technique: Anterior Knee”

Introduction

  • Knee pain is very common and it accounts for one third of all musculoskeletal (MSK) complaints. Approximately 1 million patients are seen every year in the Emergency Department (ED) with acute knee injuries.[2]Stiell IG, Greenberg GH, Wells GA, et al.: Prospective validation of a decision rule for the use of radiography in acute knee injuries. J Am Med Assoc. 1996, 275:611–5. 10.1001/jama.275.8.611[3]Pallin DJ. Knee and Lower Leg. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed. Elsevier; 2018:614-633.[4]Calmbach WL, Hutchens M. Evaluation of patients presenting with knee pain: Part II. Differential diagnosis. Am Fam Physician. 2003;68(5):917-922.
  • In the absence of acute trauma or suspicion of a fracture or dislocation, the utility of plain radiographs are low. Fractures are only seen in 6% of acute knee trauma, but radiographs still remain a mainstay in the evaluation of knee pain [5]Beutel BG, Trehan SK, Shalvoy RM, Mello MJ. The Ottawa Knee Rule: Examining use in an academic emergency department. West J Emerg Med. 2012;13(4):366-372. doi:10.5811/westjem.2012.2.6892. Soft-tissue injuries including meniscus, ligament and tendon pathology are common, but difficult to diagnose in the ED without the use of MRI. 
  • Meanwhile, musculoskeletal ultrasound (MSK US) can play an important role in the diagnosis of both osseous and soft-tissue injuries of the knee.
  • Ultrasound is an important adjunct in the ED because it is a portable, readily-available, and inexpensive imaging modality that does not have any ionizing radiation. It can be used to perform dynamic imaging, compare the symptomatic side to the asymptomatic/normal side, as well as guide therapeutic MSK procedures including joint aspirations, injections and nerve blocks.  
  • This chapter will review the basics of MSK US of the knee and a step-by-step method to scan the knee, including all the relevant anatomy and pathology that can be found in each view.

Ultrasound Probes and Settings​

  •  A high-frequency linear transducer, 10 MHz or greater, is the optimal probe to use because the majority of the structures are superficial. The curvilinear probe may be used for evaluation of the posterior knee, or in patients with large body habitus [6]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.
  • The patient should be either supine or in the Semi-Fowler’s position, with the head of bed raised 15 to 45 degrees, when scanning the anterior, medial and lateral aspects of the knee. The prone position is optimal for scanning of the posterior aspect of the knee [7]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. However, some patients may not tolerate certain positions. Patient positioning should be adjusted based on patient comfort and their degree of injury.
  • Optimize the image by placing the structure of interest in the center of the screen. 

Anatomy

  • The knee joint is the largest and most complex joint in the body, and it supports up to five times the body’s weight [8]Kraeutler MJ, Chahla J, Malagelada F, et al. Knee Anatomy and Biomechanics of the Knee. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller’s Orthopaedic Sports Medicine: Principles and … Continue reading
  • It is composed of the distal femur, proximal tibia, proximal fibula and patella, which form the tibiofemoral and patellofemoral articulations [9]Kraeutler MJ, Chahla J, Malagelada F, et al. Knee Anatomy and Biomechanics of the Knee. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller’s Orthopaedic Sports Medicine: Principles and … Continue reading
  • It is a large weight-bearing hinge joint that primarily allows for flexion and extension, but it can also accommodate rotational and translational movements [10]Abulhasan JF, Grey MJ. Anatomy and physiology of knee stability. J Funct Morphol Kinesiol. 2017;2(4). doi:10.3390/jfmk2040034. 
  • The stability of the knee is provided by both static and dynamic contributors [11]Abulhasan JF, Grey MJ. Anatomy and physiology of knee stability. J Funct Morphol Kinesiol. 2017;2(4). doi:10.3390/jfmk2040034. 
  • Static Stabilizers: Anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL) – provide static stability to the knee. [12]Kraeutler MJ, Chahla J, Malagelada F, et al. Knee Anatomy and Biomechanics of the Knee. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller’s Orthopaedic Sports Medicine: Principles and … Continue reading[13]Abulhasan JF, Grey MJ. Anatomy and physiology of knee stability. J Funct Morphol Kinesiol. 2017;2(4). doi:10.3390/jfmk2040034. 
  • Additional Static Stabilizers: The medial and lateral menisci are fibrocartilage structures that distributes compressive forces and provides some stability to the tibiofemoral joint [14] Kraeutler MJ, Chahla J, Malagelada F, et al. Knee Anatomy and Biomechanics of the Knee. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller’s Orthopaedic Sports Medicine: Principles and … Continue reading
  • Dynamic Stabilizers: The muscles surrounding the knee include the quadriceps, hamstring, gastrocnemius, tensor fascia lata, and popliteus muscles provide functional movement and dynamic stabilization of the knee. [15]Abulhasan JF, Grey MJ. Anatomy and physiology of knee stability. J Funct Morphol Kinesiol. 2017;2(4). doi:10.3390/jfmk2040034.
  • Knee flexor apparatus: comprises the hamstrings muscle group, gracilis, sartorius, gastrocnemius, popliteus, and plantaris.
  • Knee extensor apparatus: comprises the quadriceps muscle group, quadriceps tendon, patella, patella tendon, and its insertion on the tibial tuberosity. 
Bones of the knee
Ligaments of the knee
Muscles of the knee

Normal Ultrasound Anatomy​

  • The complete sonographic evaluation of the knee will include scanning all 4 quadrants: anterior, medial, lateral and posterior. The anterior knee can be further split into suprapatellar and infrapatellar views. Special attention should be given to quadrants and structures of interest based on clinical suspicion, history and physical examination. 
  • This section will focus on the views and anatomical structures that are of particular interest for Emergency Physicians. However, “additional” views and structures will be introduced that may be beyond the scope of the Emergency Department.

Anterior - Suprapatellar Views​

  • Longitudinal view: Place the transducer just above the patella in the sagittal plane with the probe marker facing towards the patient’s head to obtain a longitudinal view of the quadriceps muscles and tendon as it inserts onto the superior aspect of the patella. Deep to the quadriceps tendon will be the suprapatellar recess, a thin anechoic stripe which communicates with the rest of the joint, the prefemoral fat pad, and the anterior cortex of the distal femur. 
  • The optimal patient position is supine with the knee flexed to 30 degrees with a towel roll in the popliteal fossa. [IMAGE NEEDED]
  • Axial view: Rotate the transducer 90 degrees into the transverse plane to obtain an axial view of the quadriceps tendon and the suprapatellar recess. [IMAGE NEEDED] 
Posterior Knee View 1
Posterior Knee View 1

Anterior -Infrapatellar Views​

  • Longitudinal view: From the initial transducer position, slide the transducer over the patella, which should appear as a smooth hyperechoic cortex. Then slide further down just below the patella in the sagittal plane to obtain a longitudinal view of the patellar tendon. Deep to the patellar tendon will be Hoffa’s (infrapatellar) fat pad. The patellar tendon should be tracked all the way to the tibial tubercle. [IMAGE NEEDED]
  • Axial view: Rotate the transducer 90 degrees to obtain an axial view of the patellar tendon and Hoffa’s fat pad. [IMAGE NEEDED]
Posterior Knee View 1
Posterior Knee View 1

Medial Views​

  • Place the transducer on the medial knee in the coronal plane across the joint line to visualize the MCL, medial meniscus, and medial joint line. [IMAGE NEEDED]
    Additionally, the transducer can be moved inferiorly and anteriorly to visualize the pes anserine tendons (sartorius, gracilis, and semitendinosus) and bursa. [IMAGE NEEDED]
Posterior Knee View 1
Posterior Knee View 1

Lateral Views

  • Place the transducer on the lateral knee in the coronal plane across the joint line to visualize the lateral meniscus, and lateral joint line. [IMAGE NEEDED]
  • Additionally, when evaluating the iliotibial band, LCL, and biceps femoris tendon, move the transducer from anterior to posterior in a “Z” configuration [5]. [IMAGE NEEDED]
Posterior Knee View 1
Posterior Knee View 1

Posterior Views

  • Place the transducer on the posterior knee over the popliteal fossa in the transverse plane to locate the neurovascular bundle, including the popliteal artery and vein and the tibial nerve. Scan cephalad to visualize the sciatic nerve before it bifurcates into the tibial nerve and common peroneal nerve, which runs laterally [16]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. [IMAGE NEEDED]
  • Additionally, the semimembranosus and the medial and lateral gastrocnemius can be visualized in this position. The transducer can be rotated to the sagittal plane to visualize the posterior joint space and the posterior horns of the menisci. [IMAGE NEEDED]
Posterior Knee View 1
Posterior Knee View 2

Pathology

Joint Effusion

Suprapatellar Recess in Short Axis: No Effusion
Suprapatellar Recess in Short Axis: Effusion Present
  • Knee joint effusions are best visualized in the suprapatellar, medial, and lateral recesses with the knee in 30 degrees of flexion [5]. The most sensitive aspect is the suprapatellar recess [8]. Effusions appear on MSKUS as anechoic or hypoechoic fluid in the joint recesses. Chronic effusions may have adhesions and echogenic debris [5]. Complex fluid appears isoechoic or hyperechoic, and can be a result of septic arthritis, crystal-induced arthropathy, and hemarthrosis [5].
  • To optimize visualization of the effusion in the suprapatellar recess, ask the patient to contract their quadriceps during the diagnostic or therapeutic procedure. Alternatively, you can have an assistant apply manual pressure to the gutters and posterior capsule [9].  

Causes of Joint Effusions​

Septic Arthritis

  • Native – Effusions may be simple or complex. It is not possible to reliably determine the difference between an infectious and non-infectious arthropathy based on ultrasound examination alone. Clinically suspected septic arthritis requires an aspiration for diagnostic evaluation. However, a normal ultrasound examination without effusion has a strong negative predictive value [10]. 
  • Arthroplasty – Ultrasound guidance may augment success of periprosthetic aspiration. 
  • See: Chapter on Knee Arthrocentesis

Crystal Induced Arthropathy 

  • An effusion is the most common ultrasound finding in crystal induced arthropathy from gout or pseudogout [17]Filippucci E, Scirè CA, Delle Sedie A, Iagnocco A, Riente L, Meenagh G, Gutierrez M, Bombardieri S, Valesini G, Montecucco C, Grassi W. Ultrasound imaging for the rheumatologist. XXV. Sonographic … Continue reading.
  • See: Chapter on Gout
Hemarthrosis
Camprison Image or Video

Hemarthrosis

  • A complex effusion is typically seen with mixed echogenicity and internal echoes that infer blood products [5]. However, depending on the age of the hemarthrosis, the blood products may have layered out, resulting in a simple effusion without internal echoes.
  • Spontaneous hemarthrosis – ultrasound has a high sensitivity for low concentrations of intra-articular blood. This can be particularly useful for conditions such as hemophilic arthropathy over advanced imaging such as MRI [12].
  • Lipohemarthrosis from intra-articular fracture – A fracture results in the release of fat and blood products from the bone marrow. The fat will layer on top of the blood if the patient is lying supine. This is visualized as an echogenic layer of fat with a relatively anechoic or hypoechoic collection of blood [8].

Rheumatoid arthritis 

  • A chronic inflammatory autoimmune disorder. MSK US findings include bone erosions, synovitis, synovial and tenosynovial effusion. Power Doppler is able to detect synovial proliferation, acute inflammation and neoangiogenesis [13]. 

Osteoarthritis (see below)

Cartilage Injuries​

  • Meniscal and articular cartilage injuries can be associated with joint effusions as described above. 
  • Meniscus tears appear as a well-defined hypoechoic cleft through the meniscus that can be horizontal, vertical, complex or even displaced. Tears can be associated with a parameniscal cyst. However, MSK US does not provide complete visualization of the menisci or meniscal tears, unlike with MRI. Meanwhile, degenerative meniscus pathology appears more heterogeneous. 
Cartilage Injuries

Osteoarthritis

  • The majority of knees with osteoarthritis will demonstrate an effusion. Ultrasound findings of osteoarthritis include decreased joint space, hyaline articular cartilage thinning, meniscus extrusion, and loose intra-articular bodies [18]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. Osteophytes at the femur and tibia, synovial thickening, and popliteal cysts [LINK TO POPLITEAL CYSTS] are additional sonographic findings [19]Tarhan S, Unlu Z. Magnetic resonance imaging and ultrasonographic evaluation of the patients with knee osteoarthritis: a comparative study. Clin Rheumatol. 2003;22(3):181-188. … Continue reading. [IMAGE NEEDED] 
Knee Osteoarthritis

Fractures

  • Fractures appear on MSK US as a focal step-off that disrupts the normal bone cortex with adjacent edema and has associated tenderness to sonopalpation [20]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. Fractures surrounding the knee include distal femur, patella, proximal tibia and fibular fractures. Meanwhile, bipartite patella is a normal variant in the superolateral aspect of the patella that can mimic the appearance of a patella fracture.
  • See: Ultrasound of Bone and Fractures
Patella Fracture in Long Axis.

Ligament Injuries​

  • The collateral ligaments of the knee are located superficially so they are well-visualized with MSK US. Primarily, the transducer will be long-axis to the ligament, but pathology should also be evaluated in short-axis. US findings include hypoechoic fluid adjacent to an intact ligament (Grade 1), hypoechoic foci within the normally fibrillar ligament (Grade 2), and complete disruption of the ligament (Grade 3). Dynamic imaging with valgus and varus stress can also further evaluate collateral ligament injuries, which is discussed below. Also, ligament avulsions can be visualized as a hyperechoic osseous fragment [21]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327..
Muscle and Tendon Injuries
  • The cruciate ligaments cannot be visualized in their entirety with US. Thus, sonographic evaluation of ACL and PCL tears is limited. Abnormal findings include focal disruption, diffuse thickening, and hyperechoic bone avulsions [22]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327..  [IMAGE NEEDED]
  • Ultrasound findings of ligament injuries are further discussed in Chapter [LINK TO LIGAMENT CHAPTER].

Muscle and Tendon Injuries

  • Tendinopathy is a common cause of knee pain that results from chronic microtrauma and overuse injuries [23]McNally EG. Knee. In: Practical Musculoskeletal Ultrasound. 2nd ed. Elsevier; 2014:229-252.. It can appear on MSK US as focal tendon thickening with hypoechoic changes and disruption of the normal fibrillar pattern [24]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. Common sites of tendon injuries include the patellar (Jumper’s knee), quadriceps, semimembranosus, and biceps femoris tendons. Preexisting tendinopathic change can predispose tendons to tears [25]McNally EG. Knee. In: Practical Musculoskeletal Ultrasound. 2nd ed. Elsevier; 2014:229-252.. 
Muscle and Tendon Injuries
  • A tear on MSK US will appear as discontinuity of one or all layers of a tendon. A full-thickness tear will have an interposed hematoma between the two retracted tendon ends [26]Nori S. Quadriceps Tendon Rupture. J Family Med Prim Care. 2018;7(1):257-260. doi: 10.4103/jfmpc.jfmpc_341_16. Dynamic assessment of the tendon can differentiate partial-thickness and full-thickness injuries, which is important for management. [IMAGE NEEDED]
    The extensor mechanism of the knee can also be injured due to a quadriceps tendon rupture, patellar fracture or patellar tendon rupture [27]Hak DJ, Sanchez A, Trobisch P. Quadriceps tendon injuries. Orthopedics. 2010;33(1):40-46. doi:10.3928/01477447-20091124-20
  • The mechanism of injury is usually due to a sudden forceful contraction of the quadriceps muscle with the knee semiflexed, like when attempting to prevent a fall [28]Hak DJ, Sanchez A, Trobisch P. Quadriceps tendon injuries. Orthopedics. 2010;33(1):40-46. doi:10.3928/01477447-20091124-20
  • Typically, quadriceps tendon ruptures occur in patients older than 40 while patellar tendon ruptures occur in patients younger than 40 years old [29]Rauh MA, Parker RD. Patellar and Quadriceps Tendinopathies and Ruptures. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller’s Orthopaedic Sports Medicine: Principles and Practice. 3rd ed. … Continue reading. MRI is the most sensitive imaging modality that can also visualize the entire extensor mechanism complex and differentiate between partial and complete tears [30]Hak DJ, Sanchez A, Trobisch P. Quadriceps tendon injuries. Orthopedics. 2010;33(1):40-46. doi:10.3928/01477447-20091124-20. MSK US is a great imaging modality that is readily available in the ED to evaluate for disruptions of the extensor mechanism.
  • See: Chapter on Tendon and Ligament Ultrasound

Bursitis

  • A bursa is a synovial-lined, fluid-filled sac that provides cushion and reduces friction around the joint. They normally have a small amount of fluid that is not seen on MSK US [31]McNally EG. Knee. In: Practical Musculoskeletal Ultrasound. 2nd ed. Elsevier; 2014:229-252.. Bursae become symptomatic bursitis with fluid distension and thickening of the bursa. Mechanical/reactive bursitis appears as anechoic fluid distension, while septic and inflammatory bursitis can range from hypo- to hyperechoic fluid with hyperemia on color Doppler [32]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327..
Bursitis
  • When treating septic bursitis, recall that the majority of the bursae do not communicate with the knee joint[33]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. Common sites of bursitis include the prepatellar (“housemaid’s knee”), infrapatellar, and pes anserine bursae [34]McNally EG. Knee. In: Practical Musculoskeletal Ultrasound. 2nd ed. Elsevier; 2014:229-252.. However, it is important to remember that the suprapatellar bursa/recess does communicate with the knee joint. [IMAGE NEEDED]

Popliteal (Baker) Cyst

  • A popliteal (Baker’s) cyst is fluid distension of the semimembranosus- gastrocnemius bursa, which communicates with the knee joint. It is commonly seen in adults over 50 years of age due to knee osteoarthritis and increased intra-articular joint fluid. It appears as a C-shaped fluid collection with anechoic fluid that tracks between the semimembranosus and the medial head of the gastrocnemius tendon [35]Jacobson JA. Knee Ultrasound. In: Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia,PA: Elsevier; 2018:284-327.. Baker’s cysts are usually asymptomatic, but can cause acute pain and swelling of the calf when they rupture, which mimics a deep venous thrombosis (DVT) [36]McNally EG. Knee. In: Practical Musculoskeletal Ultrasound. 2nd ed. Elsevier; 2014:229-252.. It is important to rule out a DVT with a venous duplex ultrasound depending on the clinical context.
Baker’s Cyst

Deep Venous Thrombosis​

Video of common femoral vein compression

Iliotibial Band (Friction) Syndrome

  • Iliotibial band (ITB) friction syndrome is a common cause of lateral knee pain, especially in runners. US findings include ITB thickening and hypoechoic edema deep to the ITB and superficial to the lateral femoral condyle [37]McNally EG. Knee. In: Practical Musculoskeletal Ultrasound. 2nd ed. Elsevier; 2014:229-252..
IT Band Syndrome

Soft Tissue Hematoma​

Thigh US Large Intramuscular Hematoma
Ultrasound of quad muscles with a large, hypoechoic hematoma and a smaller one more superficial seen in short axis. Note the leveling off of blood seen in the larger view.

Osteomyelitis

  • Osteomyelitis is an infection of the bone. Findings on US include soft tissue edema, periosteal elevation and subperiosteal collections [38]Lee YJ, Sadigh S, Mankad K, Kapse N, Rajeswaran G. The imaging of osteomyelitis. Quant Imaging Med Surg. 2016;6(2):184-198. doi:10.21037/qims.2016.04.01.
Knee Osteomyelitis

Links to Ultrasound Guided Procedures

Pearls and Pitfalls​

Anistropy
Dynamic Imaging
  • Anisotropy
    • Anisotropy is an artifact in MSK US that occurs when the ultrasound beam is at an oblique insonating angle to an anatomical structure. This artifact is most prominent in tendons and muscles, but it can also be seen with ligaments and nerves. This can result in a loss of echogenicity, which can misdiagnose soft tissue injuries (false-positive finding). To avoid anisotropy, the transducer must be held strictly perpendicular to these anatomical structures, because even a few degrees of rotation off of this plane can result in abnormal-appearing hypoechoic foci that mimics soft-tissue pathology like tendinosis.
  • Dynamic Imaging
    • Dynamic imaging is an important advantage of MSK US because it can provide real-time imaging of MSK disorders. Examples include visualization of muscles and tendons during motion and muscle contraction, impingement syndromes, subluxation, and ligament pathology. Specifically for the knee, this can diagnose causes of snapping knee syndrome and visualize snapping IT band. Stress testing of the knee under ultrasound can be used to visualize collateral ligament tears, which appear as increased joint space widening and discontinuity in the normal fibrillar ligament structure that worsens with valgus/varus stress testing.
  • Patient Positioning
    • Positioning of the patient, provider and ultrasound machine should be optimized for image quality and the comfort of the patient and provider. Generally, the knee should be positioned in between the provider and the ultrasound machine so that the provider can visualize both physical anatomy and ultrasound anatomy in their line of sight. The probe marker should be positioned so that movement of the transducer relative to the structure of interest correlates with the same direction of movement on the screen. When you encounter difficulty with diagnostic or therapeutic ultrasound, take advantage of the ability to compare the symptomatic side to the asymptomatic side and scan in different positions of the knee.

Table of Structures By Quadrant

 

Quadrants of the Knee

Structures of Interest

Pathology

Anterior – Suprapatellar

Quadriceps muscle & tendon

Suprapatellar recess

Prefemoral fat pad

Femoral trochlear articular cartilage

Joint effusion

Quadriceps tear

Anterior – Infrapatellar

Patella

Patellar tendon

Tibial tubercle

Hoffa’s fat pad

Patella fracture

Patella tendon tear

Medial

Medial collateral ligament

Medial meniscus

Medial joint space

Pes anserine tendons & bursa

MCL tear

Meniscus tear

Medial compartment DJD

Pes anserine bursitis

Lateral

Lateral collateral ligament

Lateral meniscus

Lateral joint space

Iliotibial band

Biceps femoris tendon

Popliteus

Common peroneal nerve

LCL tear

Meniscus tear

Lateral compartment DJD

Posterior

Popliteal artery & vein

Posterior horns of menisci

Posterior joint space

Sciatic & tibial nerve

Semimembranosus muscle & tendon

Gastrocnemius muscles

DVT

Baker’s cyst

Calf tear

 

References

References[+]