PANCE Blueprint Musculoskeletal (8%)

Soft tissue injuries of the knee (ReelDx)

Case Presentation


Knee Pain

A 25-year-old patient presents to the ER with left knee pain

Patellar soft tissue injuries

Prepatellar Bursitis (Housemaid's Knee)

Patient will present as → a 40-year-old carpet installer who spends his working day on his knees, fitting carpets. In the past few months, he had been aware of a dull ache over his right knee, which had seemed to be aggravated by pressure and flexion of the knee. He had been wearing kneepads, using a soft mat, and trying to avoid kneeling on that knee. However, he was alarmed to wake one morning with a large, tender, fluctuant swelling over the kneecap.

Prepatellar bursitis is an inflammation of the bursa in the front of the kneecap (patella)

  • It occurs when the bursa becomes irritated and produces too much fluid, which causes it to swell and put pressure on the adjacent parts of the knee
  • Swelling over the patella. Pain with direct pressure on the knee (kneeling)
  • Common in wrestlers

DX: Concern for septic bursitis in wrestlers - aspiration with gram stain and culture

  • Serum - CBC, serum glucose, CRP, ESR, and uric acid

TX: compressive wrap, NSAIDs, +/- aspiration, and immobilization for 1 weekCorticosteroid use is controversial

  • For immunocompetent patients with mild to moderate infection, oral antibiotic therapy may be administered.

References: Merck Manual · UpToDate

Prepatellar bursitis

Prepatellar bursitis is an inflammation of the prepatellar bursa in front of the kneecap that can be caused by repeated trauma on the flexed knee (e.g., sports injuries, pressure from excessive kneeling). It is also known as Housemaid’s knee. Manifestations include pain and erythema. A minority of the cases can be complicated by septic bursitis from staphylococcus aureus. Aspiration can be done in patients with acute bursitis to rule out infectious causes of gout. NSAIDs are used to manage symptoms, and antibiotics should be added if an infectious etiology is suspected.

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Patellar Tendinitis

Patient will present as → a 22-year-old college basketball player with chronic anterior pain of her right knee. The patient has had over 6 months of physical therapy without improvement. It initially only bothered her during training, but she is now no longer able to compete and has pain with daily activities. Physical exam reveals swelling of the anterior knee and tenderness to palpation at the distal pole of the patella in full extension and no tenderness to palpation at distal pole of the patella in full flexion. Her MRI is shown here.
An injury to the tissue connecting the kneecap to the shin bone (patellar tendon)

  • Activity-related anterior knee pain associated with focal patellar tendon tenderness. Also known as "jumper's knee" (up to 20% of jumping athletes)
  • May present with swelling over the tendon and tenderness at the inferior border of the patella
  • Basset's sign: tenderness to palpation at the distal pole of the patella in full extension and no tenderness to palpation at the distal pole of the patella in full flexion

DX: History and physical examination are usually sufficient for diagnosis of infrapatellar tendinitis; however, MRI can show the extent of the injury.

TX: Ice, rest, activity modification, followed by physical therapy. Surgical excision and suture repair as needed

  • Cortisone injections are contraindicated due to the risk of patellar tendon rupture

References: Merck Manual · UpToDate

Patella Tendonitis

Patellofemoral Pain (PFP)

Patient will present as → a 27-year-old female presents with knee pain. Her pain worsens when she is running downhill or climbing up the stairs. She describes the pain as “achy” and being behind the knee. When sitting for long periods of time, she reports her knees feeling stiff. She denies any recent history of trauma and has never had surgery. She has tried multiple over-the-counter analgesics but were not effective. She is a registered dietician and an avid runner who is preparing for a marathon. A full knee examination is performed.
PFP can be defined as anterior knee pain involving the patella and retinaculum that excludes other intraarticular and peripatellar pathology

  • Overuse injury of the knee, commonly seen in young athletic women
  • Pain is poorly localized anterior knee pain, which worsens with squatting, running, prolonged sitting (theater sign), and climbing stairs
  • Commonly seen in runners or cyclists
"The term chondromalacia patella is used to describe pathologic changes in the articular cartilage of the patella, such as softening, erosion, and fragmentation. While frequently confused with PFP, chondromalacia patella is a pathologic diagnosis and constitutes a distinct cause of knee pain. - UpToDate"

DX: Although PFP is a clinical diagnosis, the diagnosis can be supported by the patellofemoral compression test (reproduction of the pain with compression of the patella during knee extension)

TX: Treatment is usually conservative with the use of physical therapy, weight loss, NSAIDs, and support braces

References: Merck Manual · UpToDate

Patellofemoral Pain Syndrome

Patellofemoral Pain Syndrome, or PFPS, is an overuse injury of the knee, commonly seen in young athletic women. Pain in this syndrome is primarily poorly localized anterior knee pain, that worsens with squatting, running, prolonged sitting, and climbing stairs. Although PFPS is a clinical diagnosis, the diagnosis can be supported by the patellofemoral compression test and the apprehension sign. Treatment is usually conservative with the use of physical therapy, weight loss, NSAIDs, and support braces.

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Ligament/Meniscal injuries

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Anterior Cruciate Ligament (ACL) Tear

Patient will present as → a 24-year-old male with severe pain in the right knee. He is a professional football player and a few hours prior to presentation, an opposing player hit his leg from his left side. Afterward, he felt a “popping” sound that was followed by severe knee pain and a sensation of knee instability. On physical exam, there is an anterior translation of the proximal tibia when pulled as the patient has the knee flexed at 90° and supine. Ice is applied to the knee and ibuprofen is prescribed. An MRI is ordered. Orthopedic surgery is consulted to evaluate if ligament reconstruction is needed.
  • Pop and swelling along with instability or "giving out" the knee after a quick plant and twist injuryMRI ACL TEAR
  • Quickly stopping movement and changing direction while running, landing from a jump, or turning leads to rotation or valgus stress of the knee and can result in injury to the ACL. Common in skiers, football, and basketball players
  • Contact injury that causes hyperextension or valgus deformation of the knee


  • Anterior Drawer Test: the proximal tibia is anteriorly pulled while the patient is supine and the knee is flexed at 90 degrees - if there is anterior translation then the test is positive
  • Lachman's Test (most sensitive): the proximal tibia is anteriorly pulled with one hand, while the other hand stabilizes the distal femur while the knee is flexed at 30 degrees

**Segond fracture is an avulsion fracture of the knee that involves the lateral aspect of the tibial plateau and is frequently (~75% of cases) associated with ACL tears

DX: Magnetic resonance imaging (MRI) can confirm the diagnosis

  • Physical therapy and lifestyle modifications for low-demand patients with decreased laxity.
  • Surgical reconstruction is performed in young and active patients with high-demand sports or jobs and/or significant knee instability.

(watch video of ACL exam)

References: Merck Manual · UpToDate

Question 1
A 33-year-old male presents to your office with a complaint of right knee injury associated with pain and swelling. He states he was running after his loose dog and suddenly stopped, hyperextended his knee, heard a pop and noticed immediate swelling. On physical examination, the Lachman test and anterior drawer test demonstrates joint laxity. Which of the following ligaments is most likely injured?
Medial collateral
Medial collateral ligament injuries often occur with rotational injuries or direct impact to the lateral knee. Tenderness medially with laxity with valgus (medial) stress is noted.
Lateral collateral
Lateral collateral ligament injury causes pain mostly on the lateral aspect of the knee and patients can experience knee buckling with normal gait. Tenderness laterally with laxity with varus (lateral) stress is noted.
Posterior cruciate
Posterior cruciate ligament injuries occur with an outside directed force, often a posterior directed force such as a knee striking a dashboard. The patients often do not hear a pop. A posterior drawer test or posterior sag test can be useful in the diagnosis.
Anterior cruciate
Question 1 Explanation: 
Anterior cruciate ligament injuries occur with sudden deceleration injuries. Patients often hear a pop and the diagnosis is aided by assessing the anterior drawer test and Lachman test. The immediate swelling as well as laxity with anterior drawer test and Lachman test should raise suspicion of anterior cruciate ligament injury.
There is 1 question to complete.
Shaded items are complete.
Anterior cruciate ligament (ACL) tear


The ACL stabilizes the knee by resisting hyperextension and anterior dislocation of the tibia during flexion. Injuries typically occur during non-contact sports such as basketball and soccer, but can also occur from trauma.

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Medial Collateral Ligament (MCL) Tear

Patient will present as → a 26-year-old college football player is brought to the emergency department after being hit on the lateral side of the left knee. He reports hearing a pop and then his knee buckled. He is now in severe pain and is having difficulty walking. On examination, there is swelling over the medial aspect of the left knee. There is laxity when a valgus stress test is performed on the knee. The results of the Lachman and McMurray tests are negative. You order an MRI of the knee with results seen here
Patient will present → after sustaining a valgus stress injury (from the outside) such as a hit in football

  • Results when the knee is forced into valgus and external rotation force to the lateral knee
  • A "pop" reported at the time of injury along with medial joint line pain and difficulty ambulating due to pain or instability
  • Testing: Valgus stress test - The patient will have pain with valgus stress applied to the knee
    • The examiner places one hand at the outside of the knee, acting as a pivot point, while the other hand is placed at the foot. The medial joint line is palpated while the examiner simultaneously applies an abducting force at the foot, and a valgus (medially directed) force through the knee joint.

DX: MRI definitive study

TX: Conservative treatment with bracing and physical therapy is typically effective

  • Surgery for chronic instability

(watch video of MCL exam)

References: Merck Manual · UpToDate

MCL TEARValgus producing stress
Medial collateral ligament (MCL) tear
A medial collateral ligament (MCL) tear is an injury of the ligament that connects the femur to the tibia on the medial aspect of the knee. It occurs in patients that have experienced high-energy trauma. It is typically treated conservatively and can be clinically observed with the valgus stress test. Play Video + Quiz

Lateral Collateral Ligament (LCL) Tear

Patient will present as → a 25-year-old soccer player injures his knee after colliding with an opposing player during a game. On physical exam, his Lachman is weakly positive. He has laxity to varus stress with the knee flexed to 30 degrees. Dial test of the tibia shows increased external rotation at 30 degrees, but not at 90 degrees in comparison to the contralateral leg.
  • The main cause of LCL injuries is direct-force trauma to the inside of the knee causing excessive varus stress, external tibial rotation, and/or hyperextension
  • Isolated injury is extremely rare - 7-16% of all knee ligament injuries when combined with lateral ligamentous complex injuries, particularly posterolateral corner (PLC) injury
  • Testing: Varus stress test
    • Flex the knee to 30 degrees. Grasping the medial aspect of the knee with one hand and the ankle with the other, apply a varus (laterally directed) force to the medial aspect of the knee. Abnormal If a gap is created in the lateral knee joint or if pain is produced.

DX: Radiographs - AP, lateral, and varus stress radiographs

  • MRI definitive study - provides information about severity (complete vs. partial rupture) and location (avulsion vs. midsubstance tear)

TX: Conservative treatment with bracing and therapy is typically effective

  • Surgery for grade III LCL injury

(watch video of LCL exam)

References: Merck Manual · UpToDate

LCL TearVarus Stress

Posterior Cruciate Ligament (PCL) Tear

Patient will present as → a 22-year-old recreational soccer player who sustained a right knee injury 6 months ago. He has been treated with rest and rehabilitation but is unable to play at his previous level due to his knee “giving way.” Physical exam reveals 10° varus alignment when standing and a varus thrust with walking. Strength is full compared to the other side. Ligamentous exam reveals a stable ACL and MCL but opens to a varus stress and a 3+ posterior drawer and positive dial test at both 30° and 90° degrees of flexion.
  • PCL injuries can also result from a blow to the knee while it is flexed, or bent, such as landing hard during sports or a fall, or from a car accident (also known as dashboard knee). May result from non-contact hyperflexion with a plantar-flexed foot or a hyperextension injury
  • Testing: Posterior drawer test, sag sign (tibia sagging posteriorly), active quad test
    • The posterior drawer test is used to assess the integrity of the posterior cruciate ligament. With the knee flexed to 90 degrees and the foot stabilized (often the examiner sits on the patient's foot), the proximal tibia is grasped firmly with both hands and the tibia is forcibly pushed posteriorly, noting any laxity compared with the other side

DX: MRI is the confirmatory study for the diagnosis of PCL injury

TX: Protected weight bearing and rehab indicated for isolated Grade I (partial) and II (complete isolated) injuries

  • Surgical repair for PCL + ACL or PCL injuries and PCL + Grade III MCL or LCL injuries

(watch video of PCL exam)

References: Merck Manual · UpToDate

Posterior Collateral Ligament (PCL) Tear

Meniscal Tear

Patient will present as → a 35-year-old man with complaints of swelling and pain in the left knee. The patient states that he sustained a twisting injury in a football game 3 days ago. The injury did not take him out of the game; he was able to continue participating with minimal difficulty. Over the last 2 days, the pain has progressed. He notes a catching sensation and pain that is more medially located. On physical examination, the patient is found to have tenderness over the medial joint line and limited range of motion. Forced flexion and circumduction of the joint cause a painful click.
  • After a twisting injury with locking, a feeling of the knee giving away, walking up and down stairs or squatting is difficult and painful
  • Triad of joint line pain, effusion, and locking
  • Effusion typically 6-24 hours after injury
  • Roughly 1/3 experience locking


  • McMurray test (watch video): the patient is supine, knee flexed and externally (medial meniscus) or internally (lateral meniscus) extended - pain indicates a tear
  • Apley compression test (watch video) will be positive: Pt prone, knee to 90 degrees, axial load with rotation causes pain with meniscal pathology

DX: Radiographs of the knee, possibly including sunrise, tunnel, posteroanterior, weight-bearing anteroposterior, and lateral views

  • MRI is the definitive study

TX: If the tear is not serious, physical therapy, compression, elevation, and icing of the knee can heal the meniscus

  • More serious tears may require surgical repair

References: Merck Manual · UpToDate

Meniscal Tear Posterior Horn Medial Meniscus
Meniscal Tear


The menisci are fibrocartilage semicircular bands that serve to stabilize the knee and absorb forces between the distal femoral condyles and the proximal tibial plateau of the knee. Injury can be sustained from trauma or in a degenerative manner. Symptoms include locking and clicking, as well as a positive McMurray test. Meniscus tears are typically managed conservatively, or in serious cases, surgery.

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