1. Chapter 9
Knee Injuries

2. Bones of the knee 4 bones in the tibiofemoral joint Tibia Femur Fibula
Patella
The knee joint complex consists of the distal femur, the proximal tibia, the proximal fibula, and the patella. The tibiofemoral (knee) joint, the largest synovial joint in the body, is a modified hinge joint. The distal end of the femur forms the convex lateral and medial condyles, which are designed to articulate with the tibia and patella. The articular surface of the medial condyle is longer from front to back than is the surface of the lateral condyle. Anteriorly, the two condyles for a hollowed groove to receive the patella.

3. Tibia “Shin” bone Major weight bearing bone in the body.
Named after a Greek aulos flute
Parts to know:
Medial Condyle
Medial Tibial Plateau
Lateral Condyle
Lateral Tibial Plateau
Intercondylar Eminence
Tibial Tuberosity
Gerdy’s Tubercle
Shaft of the Tibia
Anterior Crest
Medial Malleolus
Fibular Notch
The tibia is the larger and stronger of the two bones in the leg below the knee and it connects the knee with the ankle. The tibia is found next to the fibula on the medial side of the leg, closer to center line. The tibia is connected to the fibula by the interosseous membrane of leg, forming a type of joint called a syndesmosis with very little movement. The tibia is named for the Greek aulos flute, also known as a tibia. It is commonly recognized as the major weight bearing bone of the body.
Parts to know:
Medial Condyle - the medial portion of the upper extremity of tibia. It is the site of insertion for the Semimembranosus muscle
Medial Tibial Plateau – The smooth bony surface of the medial condyle of the tibia that articulates with the corresponding condylar surface of the femur. The medial meniscus sits on the medial plateau.
Lateral Condyle - one of two prominent bony masses at the superior end of the tibia that receives the corresponding condyle of the femur; the lateral condyle is longer than the medial condyle.
Lateral Tibial Plateau - The smooth bony surface of the lateral condyle of the tibia that articulates with the corresponding condylar surface of the femur. The lateral meniscus sits on the lateral plateau.
Intercondylar Eminence - Between the articular facets of the proximal tibia, but nearer the posterior than the anterior aspect of the bone, is the intercondylar eminence, or spine of tibia, surmounted on either side by a prominent tubercle, on to the sides of which the articular facets are prolonged; in front of and behind the intercondylar eminence are rough depressions for the attachment of the anterior cruciate ligament and posterior cruciate ligament and the menisci.
Tibial Tuberosity - an oval elevation on the anterior surface of the tibia about 3 cm distal to the articular surface, giving attachment at its distal part to the patellar ligament.
Gerdy’s Tubercle - is a lateral tubercle of the tibia, located where the iliotibial tract inserts. It was named after French surgeon Pierre Nicolas Gerdy (1797–1856).
Gerdy's tubercle - is a smooth facet on the lateral aspect of the upper part of the tibia, just below the knee joint and adjacent to the tibio-fibular joint, where the iliotibial tract runs down the outside part of the thigh.
Shaft of the Tibia – the triangular body of tibia between its expanded proximal and distal ends.
Anterior Crest of the Tibia – the sharp subcutaneous ridge of the tibia that extends from the tuberosity to the anterior part of the medial malleolus.
Medial Malleolus – is the prominence on the inner side of the ankle, formed by the lower end of the tibia.
Fibular Notch - a depression on the lateral surface of the lower end of the tibia, which articulates with the lower end of the fibula.
Anterior View
Posterior View

4. Femur “Thigh” bone Strongest bone in the body.
Longest bone in the body.
Parts to know:
Greater Trochanter
Head of the Femur
Neck of the Femur
Lesser Trochanter
Shaft of the Femur
Linea Aspera
Lateral Condyle of the Femur
Lateral Epicondyle of the Femur
Medial Condyle of the Femur
Medial Epicondyle of the Femur
Patellar Surface
Popliteal Surface
Intercondylar Fossa
The femur or thigh bone, The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and patella forming the knee joint. By most measures the femur is the strongest bone in the body. The femur is also the longest bone in the body.
Parts to know:
Greater Trochanter – The greater trochanter (great trochanter) of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and slightly posterior. In the adult it is about 1 cm lower than the head. Because the pelvic outlet in the female is larger than in the male, there is a greater distance between the greater trochanters in the female. It has two surfaces and four borders. The lateral surface, quadrilateral in form, is broad, rough, convex, and marked by a diagonal impression, which extends from the postero-superior to the antero-inferior angle, and serves for the insertion of the tendon of the gluteus medius. Above the impression is a triangular surface, sometimes rough for part of the tendon of the same muscle, sometimes smooth for the interposition of a bursa between the tendon and the bone. Below and behind the diagonal impression is a smooth, triangular surface, over which the tendon of the gluteus maximus plays, a bursa being interposed. The medial surface, of much less extent than the lateral, presents at its base a deep depression, the trochanteric fossa (digital fossa), for the insertion of the tendon of the obturator externus, and above and in front of this an impression for the insertion of the obturator internus and superior and inferior gemellus muscles. The superior border is free; it is thick and irregular, and marked near the center by an impression for the insertion of the piriformis. The inferior border corresponds to the line of junction of the base of the trochanter with the lateral surface of the body; it is marked by a rough, prominent, slightly curved ridge, which gives origin to the upper part of the vastus lateralis. The anterior border is prominent and somewhat irregular; it affords insertion at its lateral part to the gluteus minimus. The posterior border is very prominent and appears as a free, rounded edge, which bounds the back part of the trochanteric fossa.
Head of the Femur – rounded proximal articulating extremity of the femur; participates in the hip joint. The femur head (Latin: caput femoris) is the highest part of the thigh bone (femur). It is supported by the neck of the femur.
Neck of the Femur – The femur neck (femoral neck or neck of the femur) is a flattened pyramidal process of bone, connecting the femoral head with the femoral shaft, and forming with the latter a wide angle opening medial-ward. In the adult, the neck forms an angle of about 125° with the body and is 4–5 cm long.
Lesser Trochanter – a pyramidal process projecting from the medial and proximal part of the shaft of the femur at the line of junction of the shaft and the neck; it receives the insertion of the psoas major and iliacus muscles.
Shaft of the Femur – the cylindrical shaft of the thigh bone.
Linea Aspera – (Latin: rough line) is a ridge of roughened surface on the posterior surface of the femur, to which are attached muscles and intermuscular septum. Its margins diverge above and below.
Lateral Condyle of the Femur – is one of the two projections on the distal end of femur. It is more prominent and broader of the two femoral condyles, both in its antero-posterior and transverse diameters.
Lateral Epicondyle of the Femur – smaller and less prominent than the medial epicondyle, gives attachment to the lateral collateral ligament of the knee joint.
Medial Condyle of the Femur – The medial condyle is larger than the lateral (outer) condyle due to more weight bearing caused by the center of gravity being medial to the knee.
Medial Epicondyle of the Femur – a bony protrusion located on the medial side of the bone's distal end. Located above the medial condyle, it bears an elevation, the adductor tubercle, which serves for the attachment of the superficial part, or "tendinous insertion", of the adductor magnus. This tendinous part here forms an intermuscular septum which forms the medial separation between the thigh's flexors and extensors.
Patellar Surface - the groove formed anteriorly between the anterosuperior portions of the femoral condyles that accommodates the patella.
Popliteal Surface - the posterior surface of the lower end of the femur between the diverging lips of the linea aspera.
Intercondylar Fossa - is a deep notch between the rear surfaces of the medial and lateral condyles of the femur, two protrusions on the distal end of the femur (thigh bone) that joins the knee.
Anterior view
Posterior view

5. Patella Largest sesamoid bone in the body.
Enclosed in quadriceps femoris tendon.
Illustration is of the right patella
Parts to know:
Base
Apex
Medial Facet
Lateral Facet
The patella is a thick, circular-triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. In humans, the patella is the largest sesamoid bone in the body. Babies are born with a patella of soft cartilage which begins to ossify into bone at about three years of age.
The lateral aspect is wider than the medial aspect. The patella articulates between the concavity provided by the femoral condyles. Tracking within this groove depends on the pull of the quadriceps muscles and the patellar tendon, the depth of the femoral condyles, and the shape of the patella. Poor tracking can lead to subluxation, dislocation, or degeneration of the articular cartilage.
Parts to know:
Base - the superior border of the patella, opposite its apex, to which the tendon of the rectus femoris attaches.
Apex – the pointed inferior end of the patella from which the patellar tendon passes to insert on the tibial tuberosity.
Medial Facet – Posterior surface of the patella that articulates with the medial condyle of the femur; generally smaller than the lateral facet.
Lateral Facet - Posterior surface of the patella that articulates with the lateral condyle of the femur; generally larger than the medial facet.

6. Ligaments and Cartilage of the knee
Ligaments of the Knee
Anterior Cruciate Ligament (ACL)
Posterior Cruciate Ligament (PCL)
Medial Collateral Ligament (MCL)
Lateral Collateral Ligament (LCL)
Meniscus of the Knee
Medial Meniscus
Lateral Meniscus
Anterior Cruciate Ligament – attaches to the anterior aspect of the intercondylar eminence and inserts on the posterior/inner surface of the lateral condyle of the femur. Prevents the femur from moving posteriorly during weight bearing. The anterior and posterior cruciate ligaments, one on either side of the knee, are so called because they cross each other in front of the knee. "Cruciate" taken from the Latin "crux" for "cross" means "in the form of a cross."
Posterior Cruciate Ligament – stronger of the 2 cruciate ligaments, originates on the posterior aspect of the intercondylar eminence and inserts on the anterior/inner portion of the medial condyle. Prevents hyperextension of the knee joint.
Medial Collateral Ligament – flat, fibrous tissue that attaches on medial aspect of the medial condyle near the pes anserinus of the tibia and attaches on the medial aspect of the medial epicondyle of the femur. Resists valgus stress and external rotating forces. Pes anserinus ("goose foot") refers to the conjoined tendons of three muscles that insert onto the anteromedial (front and inside) surface of the proximal extremity of the tibia. The muscles are the sartorius, gracilis and semitendinosus. The name, "goose foot", arises from the three pronged manner in which the conjoined tendon inserts onto the tibia.
Lateral Collateral Ligament – round, fibrous cord that is shaped like a pencil. Attaches to the lateral epicondyle and the head of the fibula. Resists varus stress and internal rotating forces.
The menisci are two half-moon shaped fibrocartilages that deepen the articular facets of the tibia, cushion any stresses placed on the knee joint, and maintain spacing between the femoral condyles and the tibial plateau. Consistency of the menisci is much like intervertebral disks.
Medial meniscus is “C” shaped. Lateral meniscus is “O” shaped. Outer 1/3 of meniscus has good blood supply, middle 1/3 has minimal blood supply, and the inner 1/3 is avascular (devoid of blood circulation).

7. Flexion Extension Medial Rotation Lateral Rotation
Range of Motion
Flexion Extension Medial Rotation Lateral Rotation
Flexion/Extension – 0 – 135 degrees for full normal ROM at the knee joint.
Medial/Lateral Rotation – 0 – 30 degrees medial (internal) rotation, 0 – 40 degrees lateral (external) rotation; happens with knee flexed at 90 degrees.

8. Muscles of the knee Rectus Femoris Origin Insertion Action
Anterior Inferior Iliac Spine (AIIS)
Insertion
Tibial Tuberosity via the patellar tendon
Action
Extend the knee
Flex the hip
Two –joint muscle so will have actions at both joints.
Large muscle over the femur

9. Muscles of the Knee Vastus Lateralis Origin Insertion Action
Lateral lip of linea aspera, gluteal tuberosity, and greater trochanter.
Insertion
Tibial Tuberosity via the patellar tendon.
Action
Extend the knee.
Vastus = Large
Lateralis = Lateral side

10. Muscles of the Knee Vastus Intermedius Origin Insertion Action
Anterior and lateral shaft of the femur.
Insertion
Tibial Tuberosity via the patellar tendon.
Action
Extend the knee.
Only visible on the deep view because it lies under the Rectus Femoris muscle.
Vastus = Large muscle
Intermedius = in the middle

11. Muscles of the Knee Vastus Medialis Origin Insertion Action
Medial lip of the linea aspera.
Insertion
Tibial tuberosity via the patellar tendon.
Action
Extend the knee.
Vastus = Large muscle
Medialis = Medial side
Rectus Femoris, Vastus Lateralis, Vastus Intermedius and Vastus Medialis for the Quadriceps group. Quad = 4 ceps = heads.

12. Muscles of the knee Semimembranosus Origin Insertion Action
Ischial tuberosity.
Insertion
Posterior aspect of medial condyle of tibia.
Action
Flex the knee
Medially rotate the flexed knee
Extend the hip
Assist in medially rotating the hip
Tilt the pelvis posteriorly
Sits under the Semitendinosus muscle.

13. Muscles of the Knee Semitendinosus Origin Insertion Action
Ischial tuberosity.
Insertion
Proximal, medial shaft of the tibia at pes anserinus.
Action
Flex the knee
Medially rotate the flexed knee
Extend the hip
Assist to medially rotate the hip
Tilt the pelvis posteriorly
Sits over the Semimembranosus muscle.

14. Muscles of the Knee Biceps Femoris Origin Insertion Action
Long head: Ischial tuberosity.
Short head: Lateral lip of the linea aspera.
Insertion
Head of the fibula.
Action
Flex the knee
Laterally rotate the flexed knee
Long head: extend the hip
Long head: Assist to laterally rotate the hip
Tilt the pelvis posteriorly

15. Muscles of the Knee Sartorius Origin Insertion Action
Anterior Superior Iliac Spine (ASIS)
Insertion
Proximal, medial shaft of the tibia at the pes anserinus
Action
Flex the hip
Laterally rotate the hip
Abduct the hip
Flex the knee
Medially rotate the flexed knee
Longest muscle in the human body

16. Muscles of the Knee
Sartorius (posterior view)

17. Muscles of the Knee Gracilis Origin Insertion Action
Inferior ramus of the pubis
Insertion
Proximal, medial shaft of the tibia at pes anserinus
Action
Adduct hip
Medially rotate hip
Flex the knee
Medially rotate the flexed knee

18. Muscles of the Knee Popliteus Origin Insertion Action
Lateral condyle of the femur
Insertion
Proximal, posterior aspect of the tibia
Action
Medially rotate the flexed knee
Flex the knee

19. Muscles of the Knee Gastrocnemius Origin Insertion Action
Condyles of the femur, posterior surfaces
Insertion
Calcaneus via the Achilles tendon
Action
Flex the knee
Plantar flex the ankle

20. Muscles of the Knee Plantaris Origin Insertion Action
Lateral supracondylar line of the femur.
Insertion
Calcaneus via the Achilles tendon
Action
Plantar flexion of the ankle
Flexion of the knee

21. Muscles of the Knee Tensor Fascia Latae and the Iliotibial Band Origin
Iliac crest, posterior to the ASIS
Insertion
Iliotibial tract (which then inserts on the tibial tubercle on the lateral aspect of the proximal tibia)
Action
Flex the hip
Medially rotate the hip
Abduct the hip
Tensor = a stretcher
Fascia = connective tissue
Latae = broad

22. Assessment Tests
Valgus Test Varus Test Anterior Drawer Lachman’s Test Posterior Drawer Test Godfrey’s Test/Posterior Sag Test
McMurray’s Test Apley’s Compression Test Apley’s Distraction Test Patellar Apprehension Test Patellar Grind Test/Clarke’s Sign

23. Knee Injuries & Conditions
Ligament Sprain MCL LCL ACL PCL Jumper’s Knee Osgood-Schlatter Disorder Quadriceps Strain Hamstrings Strain Patellar Subluxation/Dislocation Chondromalacia patella Meniscal Injuries Bursitis Iliotibial Band Friction Syndrome Osteochondritis Dissecans

24. Medial Collateral Ligament Sprain
Etiology MCL Injury Pathology Treatment
Etiology – Usually results from a direct blow to the outside of the knee while the foot is planted or due to a severe outward twist. The position of the knee at the time of injury usually determines the vulnerability of the knee to traumatic sprains. Full extension tightens both the LCL and MCL, while flexion causes a loss of stability to the LCL, but maintains stability on the MCL which is a broad (wider) ligament. The force and angle of the trauma usually determine the extent of the injury. The most reliable and accurate readings for severity of the injury will be testing the ligaments immediately after the injury has occurred.
Pathology – Divided into graded injuries (1st, 2nd, or 3rd degree).
1st degree – Mild stretch of the ligament, joint is stable during valgus test, little to no joint effusion (fluid within the joint; joint swelling), some stiffness, point tenderness around medial joint line, full PROM and AROM.
2nd degree – Partial tear of the ligament and or joint capsule, no gross instability, some laxity on full extension valgus test, 5-15 degrees of laxity on 30 degree flexion valgus test, minor swelling unless another structure like the meniscus or ACL/PCL involved, moderate to severe tightness with the inability to fully extend the knee, athlete is unable to place heel flat on the ground, decreased PROM, pain over medial aspect of the knee, and general weakness and a feeling of instability present in the athlete.
3rd degree – Complete tear of MCL, loss of stability, moderate swelling, immediate sharp pain followed by dull ache, loss of ROM due to joint effusion and hamstring guarding, valgus test reveals opening in full extension and significant opening in 30 degree flexion test.
Isolated grade 3 MCL sprains most often occur when the mechanism of injury involves a direct valgus force with the foot fixed (planted) and loaded (weight-bearing). MCL tears resulting from rotation combined with a valgus force with the foot fixed almost always result in ACL and sometimes PCL tears as well.
Treatment – PRICE for up to the first 72 hours (24 for 1st degree, 48 for 2nd degree). Weight bearing should be limited if the athlete cannot walk without a limp for 1st, 2nd or 3rd degree injuries. In 2nd and 3rd degree injuries a knee immobilizer will be used from 2-5 day (2nd degree) to up to 4-6 weeks (3rd degree). Surgery is usually not required for isolated MCL tears, but will be done if other structures are involved (ACL/PCL or meniscus). Rehabilitation time will vary depending upon the degree of injury with 1st degree being around 1-2 weeks and 3rd degree being 4-6 weeks or more if surgery was required. Stationary biking and stair climbing should be started as part of a rehabilitation program as soon as possible (while being pain free). When the athlete has been cleared to do so, strength training should focus on quadriceps and hamstrings to help make the knee joint more stable. A hinged brace should be worn for 2nd and 3rd degree sprains while participating in practices, games, or just running.

25. Lateral Collateral Ligament Sprain
Etiology LCL Injury Pathology Treatment
This injury is much less prevalent than a MCL injury.
Etiology – requires a varus force to be applied to the inside of the knee. Often includes internal tibial rotation. Because the medial aspect of the knee is usually inaccessible, a direct blow is rare. LCL injuries occurring in snow skiers who allow the tips of the skis to cross while performing a “snowplow” maneuver to slow/stop. It is not uncommon to see and avulsion fracture associated with a LCL injury of either the lateral femoral epicondyle or of the fibular head.
Pathology – Pain and tenderness over the LCL. With the knee flexed and internally rotated, you may be able to palpate the tear site. Swelling and joint effusion over the LCL site. Some laxity with varus stress test at 30 degrees. If laxity still exists in full extension ACL and PCL should be examined. Pain will be the greatest with a Grade 1 or 2 sprain. Grade 3 will initially be intense then fade quickly to a dull ache. Athlete may complain of hearing/feeling a “pop, snap, crack.” May also involve the peroneal nerve causing temporary, or even permanent palsy (paralysis, especially that which is accompanied by involuntary tremors).
Treatment - PRICE for up to the first 72 hours (24 for 1st degree, 48 for 2nd degree). Weight bearing should be limited if the athlete cannot walk without a limp for 1st, 2nd or 3rd degree injuries. In 2nd and 3rd degree injuries a knee immobilizer will be used from 2-5 day (2nd degree) to up to 4-6 weeks (3rd degree). Surgery is usually not required for isolated LCL tears, but will be done if other structures are involved (ACL/PCL or meniscus). Rehabilitation time will vary depending upon the degree of injury with 1st degree being around 1-2 weeks and 3rd degree being 4-6 weeks or more if surgery was required. Stationary biking and stair climbing should be started as part of a rehabilitation program as soon as possible (while being pain free). When the athlete has been cleared to do so, strength training should focus on quadriceps and hamstrings to help make the knee joint more stable. A hinged brace should be worn for 2nd and 3rd degree sprains while participating in practices, games, or just running.

26. Anterior Cruciate Ligament Sprain
Etiology ACL Injury Pathology Treatment
This is considered to be the most serious ligament injury of the knee.
Etiology – Most vulnerable when the tibia is externally rotated and the knee is in a valgus position. Can happen with sudden deceleration and making a sharp cutting motion, direct blow to the knee just superior to the joint, or a twist of the knee medially or laterally. Hyperextension of the knee joint can also cause a tear of the ACL. Female athletes are more likely to tear their ACL than males because of the Q-angle (the angle between the quadriceps muscle (primarily the rectus femoris) and the patellar tendon) of the hip.
Pathology – Athlete may complain of hearing/feeling a “pop, snap, or crack” followed by immediate disability and may complain of the knee feeling like it is “coming apart.” ACL tears generally produce rapid swelling at the joint line. The athlete with an isolated ACL tear will exhibit positive anterior drawer test and lachman’s test. Weight bearing may be difficult to impossible so crutches should be issued.
Treatment – PRICE for the first hours. Even with constant treatment noticeable swelling is likely to occur. Typically cannot walk without a limp. Surgery will be based on the severity of the injury and the athlete’s age. Surgery is generally required to repair Grade 2 or 3 sprains. Surgery usually requires up to 6 months recovery time including healing and rehab time to be returned to activity, but most athletes do not truly reach their “normal” level of play until 1 full year after the rehabilitation has been completed. Most physicians will require the athlete to wear some sort of brace initially when returning to sports, but may allow them to gradually stop using the brace as strength to the knee returns.

27. Posterior Cruciate Ligament Sprain
Etiology PCL Injury Pathology Treatment
Etiology – PCL is at risk when the knee is flexed at 90 degrees. A fall with full weight on the anterior aspect of the bent knee with the foot in plantar flexion or receipt of a hard blow to the front of the knee can tear the PCL. It can also be injured by rotational force, which may also affect the medial and/or lateral collateral ligaments.
Pathology – Athlete may report hearing/feeling a “pop, snap, crack” in the back of the knee. Tenderness and minimal swelling in the popliteal fossa (knee pit). Laxity will be demonstrated in a posterior drawer/Godfrey’s sag test. The athlete may feel some instability and may have a limp.
Treatment – PRICE should be initiated immediately and should be continued for at least the first 72 hours. Nonoperative rehabilitation of Grade 1 and 2 sprains should focus on quadriceps strengthening. Surgery of the PCL is generally more difficult to perform and therefore the preferred method is nonoperative rehabilitation, however surgeries are occasionally recommended. Rehab after surgery generally involves 6 weeks of immobilization in extension with full weight bearing on crutches. ROM exercises are begun at six weeks, progressing to the use of PREs (Progressive Resistance Exercises) at four months.

28. Jumper’s Knee (Patellar Tendinitis)
Etiology Pathology Treatment
Etiology – Jumping, as well as kicking or running, may place extreme tension on the knee extensor complex (quads and patellar tendon). As a result of one or more commonly repetitive injuries, tendinitis occurs in the patellar or quadriceps tendon. On rare occasions the patellar tendon may completely rupture. Sudden or forceful extension of the knee may begin the inflammatory process that will eventually lead to tendon degeneration.
Pathology – The athlete will report pain and tenderness at the inferior end of the patella near the apex and posterior aspect. Patellar tendinitis has three stages:
Stage 1 – pain after sports
Stage 2 – pain during and after activity; athlete is able to perform at the appropriate level.
Stage 3 – pain during activity and prolonged after activity (athletic performance is hampered); may progress to constant pain and complete rupture.
Treatment – PRICE initially for first hours. Icing can be done effectively with ice massage for minutes at least 3 x’s a day. After 2-3 days of icing, heat, in the form of a hot pack or even ultrasound (if prescribed by a physician) can start to be used prior to activity. Stretching of the quadriceps may relieve tension on the patellar tendon. Use of a patellar strap has work well. Deep transverse friction massage has also been shown effective in treating Jumper’s knee. Ice massages should be continued after activity to prevent the return of the tendinitis.

29. Patella Tendon Rupture
Etiology Patella Tendon Rupture Injury Pathology Treatment
Etiology – A sudden powerful contraction of the quadriceps muscle with the weight of the body applied to the affected leg can cause a rupture. The rupture may occur to the quadriceps tendon (superior to the patella) or patellar tendon (inferior to the patella). Usually a rupture does not occur unless there has been an inflammatory condition over a period of time in the region of the knee extensor mechanism, causing tissue degeneration. A rupture seldom occurs in the middle of the tendon; usually it is closer to the attachment site. The quadriceps tendon usually ruptures from the superior pole (base) of the patella.
Pathology – The patella moves upward toward the thigh if the patella tendon is ruptured and the defect (rupture) can be palpated. The athlete cannot extend the knee. There is considerable swelling with significant pain initially, followed by the feeling that the injury may not be all that serious.
Treatment – A rupture will require surgical repair. Treat initially with PRICE and transport immediately to ER. Proper conservative care of jumper’s knee (tendinitis) can minimize the chances of patellar tendon rupture. Athletes who use anti-inflammatory drugs such as steroids must avoid intense exercises involving the knee. Steroids injected into these tendons weaken collagen fibers and mask pain. After surgery the athlete will be in an immobilizer for 4-6 weeks followed by rehabilitation for up to 6 months.

30. Osgood-schlatter Disease/Shinding-Larsen-Johansson Disease
Etiology Pathology Treatment
Etiology – Two conditions common to the immature adolescent’s knee are Osgood-Schlatter disease and Shinding-Larsen-Johansson disease. Osgood-Schlatter disease is an apophysistis (inflammation of the apophysis, a bony protuberance) characterized by pain at the attachment site of the patellar tendon to the tibial tuberosity. This condition most often represents an avulsion fracture of the tibial tuberosity. This fragment is cartilaginous initially, but with growth, a bony callus forms and the tuberosity enlarges. The condition usually resolves itself when the athlete reaches the age of The only remnant is a large tibial tuberosity. The most commonly accepted cause of Osgood-Schlatter disease is repetitive avulsion of the patellar tendon at the apophysis of the tibial tuberosity. Complete avulsion of the patellar tendon is a major complication of Osgood-Schlatter disease.
Shinding-Larsen-Johansson disease is similar to Osgood-Schlatter disease, but it occurs at the inferior pole (apex) of the patella. Like to cause of Osgood-Schlatter disease, the cause of Shinding-Larsen-Johansson disease is believed to be repetitive stress on the patellar tendon. Swelling, pain, and point tenderness characterize Shinding-Larsen-Johansson disease. Later, degeneration can be noted on x-rays.
Pathology – Repeated irritation causes swelling, hemorrhage, and gradual degeneration of the apophysis as a result of impaired circulation. The athlete complains of severe pain when kneeling, jumping and running. There is point tenderness over the anterior proximal tibial tuberosity. Very common in adolescent males, but can occur with adolescent females as well.
Treatment – Management is usually conservative. PRICE can be used initially, but must be seen by a physician for x-ray/MRI. Stressful activities are decreased until the epiphyseal union occurs, within six months to one year. Severe cases may required casting. Ice is applied to the knee before and after activities. Isometric exercises (are a type of strength training in which the joint angle and muscle length do not change during contraction [compared to concentric or eccentric contractions, called dynamic/isotonic movements]) for quadriceps and hamstring strengthening are performed.

31. Etiology Quad injury Pathology Treatment
Quadriceps Strain
Etiology Quad injury Pathology Treatment
Etiology – On occasion, the rectus femoris muscle will be strained by a sudden stretch, such as when an athlete falls on a bent knee, or a sudden contraction, such as when an athlete jumps in volleyball or kicks in soccer. Usually the strain is associated with a muscle that is weakened or one that is overly constricted. It will be a stretch, partial tear, or complete tear of one or more of the quadriceps muscles, but the rectus femoris is the most commonly injured quad muscle.
Pathology – Grade 1 strains cause fewer symptoms than Grade 2 or 3 strains. Point tenderness and swelling will be present, the higher the grade of strain the more tenderness and swelling present. The more centrally the tear is located the more painful it usually is. With deep tears there is a great deal of pain, point tenderness, spasm, loss of function but little discoloration from internal bleeding. A complete tear of the rectus femoris may leave the athlete with little disability and discomfort, but may leave some deformity present on the anterior thigh.
Treatment – Initially PRICE, NSAIDs, and analgesics are given as needed. The extent of the tear needs to be determined before swelling occurs if possible. Crutches may be warranted for any grade if the athlete cannot walk without a limp for 1-3 days. After pain has subsided and healing has begun, isometric exercises (within pain-free limits) can be initiated along with continued cryotherapy. Cold whirlpools, ultrasound, electric stimulation, and gentle stretching can also be used to help with symptoms that may still be present. An elastic wrap or thigh sleeve should be used for support when returning to participation, but the athlete can be weaned off it as they recover.

32. Etiology Hamstring Injury Pathology Treatment
Hamstrings Strain
Etiology Hamstring Injury Pathology Treatment
Hamstring strains are among the most common injuries to the thigh. Athletes suffer more strains to the hamstring muscles than any other muscle of the thigh.
Etiology – The exact cause is not known. One theory is that the short head of the biceps femoris muscle is subject to the highest incidence of hamstring strain because, as a result of an idiosyncracy of innervation, it contracts at the same time that the quadriceps muscle does. Another speculation is that a quick change of the hamstring muscle from a role of knee stabilization to that of extending the hip when running could be the major cause of strain. What leads to muscle failure and deficiency in the complementary action of opposing muscles is not clearly understood. Possible reasons could be muscle fatigue, faulty posture, leg-length discrepancy, tight hamstrings, improper form, adverse neural tension, or an imbalance of muscle strength between the hamstring group and quadriceps group. Hamstring muscles function as decelerators of the leg swing and commonly become injured when an athlete suddenly changes direction or starts to slow. In most athletes, the hamstring group should have a strength of 60-70% of that of the quadriceps group.
Pathology – Graded as other strains into Grade 1, Grade 2, or Grade 3. Grade 1 injury would be a stretch of one or more of the hamstrings with minor tenderness and pain especially after cool down is completed. Soreness is usually attributed to muscle spasm in a Grade 1 injury. Grade 2 injuries are partial tears of one or more of the hamstring muscles. Pain, discoloration, loss of function are common with Grade 2 injuries, although discoloration may not appear until a few days later. Athlete may complain of a sudden “snap, crack, pop” in the back of the thigh. Grade 3 injuries are usually dealing with complete tears of one or more hamstring muscles or avulsion fractures associated to the hamstring attachments on the pelvis. Severe edema, tenderness, loss of function, ecchymosis, and a palpable mass or gap in the muscle may be present.
Treatment – Initially PRICE, NSAIDs, and analgesics are given as needed. Activity should be reduced until soreness goes away. Athletes should not be allowed to return to activity until full ROM and strength are at normal levels. Grade 2 and 3 injuries need to be treated conservatively for the first 72 hours. After the inflammatory phase has been stabilized, a treatment regimen od isometric exercises, cryotherapy, ultrasound and electric stimulation can be of benefit. Gentle stretching should be done only if pain-free. When full ROM is restored a gradual return is important starting with jogging/stationary bike and isokinetic exercises (Exercise performed using a specialized apparatus that provides variable resistance to a movement, so that no matter how much effort is exerted, the movement takes place at a constant speed). After the elimination of soreness, the athlete may begin isotonic (Exercise when a contracting muscle shortens against a constant load, as when lifting a weight. Isotonic exercise is one method of muscular exercise. In contrast, isometric exercise is when muscular contractions occur without movement of the involved parts of the body. Isotonic comes from the Greek "iso-", equal + "tonos", tone = maintaining equal (muscle) tone. The muscle maintains equal tone while shortening in isotonic exercise) knee curls. Full recovery may take from one month to a full season.
Strains are always a problem to the athlete because they tend to recur as a result of inelastic, fibrous scar tissue that sometimes forms during the healing process. The higher the incidence of strains at a particular sight, the greater the amount of scar tissue and the greater likelihood of further injury will be. Muscle rehabilitation should emphasize eccentric exercises (active contraction of a muscle occurring simultaneously with lengthening of the muscle; ex. lowering weights back down after doing a hamstring curl).

33. Patellar Subluxation/Dislocation
Etiology Patellar Dislocation Pathology Treatment Patellar Reduction
Etiology – When an athlete plants his or her foot, decelerates, and simultaneously cuts in an opposite direction from the weight-bearing leg, the thigh internally rotates while the lower leg is externally rotated, causing a forced knee valgus. The quadriceps muscles attempt to pull in a straight line and as a result pulls the patella laterally – a force that may dislocate the patella. As a rule, displacement takes place outwardly, with the patella resting on the lateral condyle. With this mechanism, the patella is forced to slide laterally into a partial or full dislocation. Some athletes are more predisposed to this condition because of the following anatomical structures:
Wide pelvis with anteverted (tilted forward) hips
Genu valgum (commonly called "knock-knee", is a condition in which the knees angle in and touch one another when the legs are straightened. Individuals with severe valgus deformities are typically unable to touch their feet together while simultaneously straightening the legs), which increases the Q-angle (the angle between the quadriceps muscle (primarily the rectus femoris) and the patellar tendon).
Shallow femoral grooves
Flat lateral femoral condyles
High-riding and flat patellas
Vastus medialis and ligamentous laxity with genu recurvatum (a deformity in the knee joint, so that the knee bends backwards) and externally rotated tibias
Pronated feet (pes planus)
Externally pointing patellas
A patella that subluxes repeatedly places abnormal stress on the patellofemoral joint and the medial restraints.
Pathology – The athlete experiences pain, swelling, and a complete loss of knee function, and the patella rests in an abnormal position. The physician will reduce the patella by applying mild pressure on the patella with the knee moved into extension as much as possible. A general anesthetic may be used. Joint hematoma may be aspirated (drained), ice is applied, and the joint is splinted. X-ray may be done to rule out any kind of chondral fracture.
Treatment – PRICE should be applied and the athlete should be splinted in the position found. EMS should be activated and transport the athlete to the ER where they will then have the patella reduced by a physician. The knee is immobilized for a minimum of 4 weeks and crutches will be issued. Isometric exercises should be performed while in the splint. After immobilization, the athlete should wear a horseshoe-shaped pad to help keep the patella in place with an ace wrap or us a sleeve brace that has the pad sewn in. Muscle rehab should focus on all the musculature of the knee, thigh and hip. Knee exercises should be confined to straight leg raises. Surgery may be performed to release restrictive ligaments or to reconstruct the patellofemoral joint. Postural malalignments should be corrected as much as possible.

34. Chondromalacia Patella
Etiology Pathology Treatment
Etiology – Chondromalacia Patella is a softening and deterioration of the articular cartilage on the posterior aspect of the patella (part closest to the patellofemoral joint). Chondromalacia undergoes three stages
Stage 1 – swelling and softening of the articular cartilage
Stage 2 – fissuring of the softened articular cartilage.
Stage 3 – deformation of the surface of the articular cartilage caused by fragmentation.
The exact cause of chondromalacia is unknown. Abnormal patellar tracking could be a major etiological factor; however, individuals with normal tracking have acquired chondromalacia, and some individuals with abnormal tracking are free of it. Abnormal patellofemoral tracking can be produced by genu valgum, external tibial torsion, foot pronation, femoral anteversion, a quadriceps Q-angle greater than degrees, patella alta (high riding patella; describes a situation where the position of patella is considered high. It can be idiopathic or can result secondary to a patellar tendon rupture), a shallow femoral groove, a shallow articular angle of the patella, an abnormal contour of the patella, or laxity of the quadriceps tendon.
Pathology – The athlete may experience pain in the anterior aspect of the knee while walking, running, ascending/descending stairs, or squatting. There may be recurrent swelling around the kneecap and a grating sensation when flexing and extending the knee. The patella displays crepitation during the patellar grind test. During palpation there may be pain on the inferior border of the patella or when the patella is compressed within the femoral groove while the knee is passively flexed and extended. The athlete has one or more lower-limb alignment deviations. Degenerative arthritis (inflammation of the patellofemoral joint) occurs on the medial facet of the patella, which makes contact with the femur when the athlete performs a full squat. Degeneration first occurs in the deeper portions of the articular cartilage, followed by blistering and fissuring that stems from the subchondral bone (below the cartilage) and appears on the surface of the patella.
Treatment – Usually treated conservatively by:
Avoiding irritating activities
Doing isometric exercises if pain free to strengthen the quadriceps and hamstring muscles
Oral anti-inflammatory agents and small doses of aspirin
Neoprene sleeve
Orthotics to correct malalignments as much as possible
Moving the insertion of the vastus medialis muscle forward through realignment procedures such as lateral release of the retinaculum (surgical procedure).
Shaving and smoothing the irregular surfaces of the patella, femoral condyle, or both
In cases of degenerative arthritis, removing the blister through drilling
Elevating the tibial tuberosity
As a last resort, completely removing the patella (rarely done).

35. Etiology Pathology Treatment
Meniscal Injuries
Etiology Pathology Treatment
The medial meniscus has a much higher incidence of injury than the lateral meniscus because the coronary ligament attaches the medial meniscus peripherally to the tibia and also to the capsular ligament. The lateral ligament does not attach to the capsular ligament and is more mobile during knee movement. Because of the attachment to the medial structures, the medial meniscus is prone to disruption from valgus and torsional forces.
Etiology – The most common mechanism is weight bearing combined with a rotary force while the knee is extended or flexed. If the athlete makes a cutting motion while running, it can distort the medial meniscus. Stretching of the anterior and posterior horns of the meniscus can produce a vertical-longitudinal, or “bucket-handle” tear. Another way the longitudinal tear occurs is if the knee is forcefully extended from a flexed position while the femur is internally rotated. During extension the medial meniscus is suddenly pulled back, causing the tear. In contrast, the lateral meniscus can sustain an oblique tear by a forceful knee extension with the femur externally rotated. A large number of medial meniscus tears are the outcome of a sudden, strong internal rotation of the femur with a partially flexed knee while the foot is firmly planted. The force of this action pulls the meniscus out of its normal bed and pinches it between the femoral condyles. Meniscal tear can be oblique, transverse or longitudinal. Because of its blood supply, tears in the outer-third of a meniscus my heal over time if stress in the area is minimized. Tears that occur within the midsubstance of the meniscus often fail to heal because of the lack of adequate blood supply.
Pathology – An absolute diagnosis of meniscal injury is difficult. To determine the possibility of such an injury, the ATC should obtain a complete history which consists of information about past knee injuries and an understanding of how the present injury occurred. Diagnosis of meniscal injuries should be made immediately after the injury has occurred and before muscle spasm and swelling obscure the normal shape of the knee. A meniscal tear may or may not result in the following:
Effusion developing gradually over hours.
Joint-line pain and loss of motion.
Intermittent locking and giving way of the knee.
Pain when the athlete squats.
Once a tear occurs, the ruptured edge hardens and may eventually atrophy (waste away, typically due to the degeneration of cells, or become vestigial during evolution). On occasions, portions of the meniscus may become detached and wedge themselves between the articulating surfaces of the tibia and femur, thus imposing a locking, catching, or giving way of the joint. Chronic meniscal tears may also display recurrent swelling and obvious muscle atrophy around the knee. The athlete may complain of a sense of the knee collapsing, of a popping sensation, or of an inability to perform a full squat or to change direction quickly without pain when running. Such symptoms and signs usually warrant surgical intervention. Symptomatic meniscal tears can eventually lead to serious articular degeneration with major impairment and disability.
Treatment – PRICE and refer to physician if suspected. May need to limit weight bearing and issue crutches is unable to walk without a limp or feeling of instability present. Physician may order a MRI to try to find the meniscal tear. A diagnostic arthroscopic examination may also be performed. The knee that is locked by a displaced meniscus may require unlocking with the athlete under anesthesia so that a detailed examination can be conducted. If discomfort, disability, and locking of the knee continue, arthroscopic surgery may be required to remove portions of the meniscus. Post-surgical management for a partial menisectomy (removal of a piece of meniscus) does not usually require bracing and allows partial to full weight bearing on crutches as quickly as tolerated for about two weeks. It is not uncommon for an athlete to return to full activity in as little as 6 – 14 days. A repaired meniscus requires immobilization in a rehabilitative brace for 5-6 weeks. The athlete should use crutches, progressing from partial to full weight bearing at six weeks. During immobilization, the athlete can perform AROM exercises between 0 – 90 degrees. At six weeks, full ROM resistive exercises can begin. Rehabilitation should concentrate in endurance training.

36. Etiology Pathology Treatment
Bursitis
Etiology Pathology Treatment
Bursitis in the knee can be acute, chronic, or recurrent. Although any one of the numerous knee bursae can become inflamed, anteriorly the prepatellar, deep infrapatellar, and suprapatellar bursae have the highest incidence of irritation in sports.
Etiology – The prepatellar bursa often becomes inflamed from continual kneeling, and the deep infrapatellar bursa becomes irritated from overuse of the patellar tendon.
Pathology – Prepatellar bursitis results in localized swelling above the knee that is ballotable (A condition in which the patella has a mass which is palpable and which can be “bounced” back and forth because of an effusion of blood or fluid in the capsule of the knee joint). Swelling is not intraarticular, and there may be some redness and increased temperature to the touch. Swelling in the popliteal fossa (posterior aspect of the knee) does not necessarily indicate bursitis but could be a sign of a Baker’s cyst. A Baker’s cyst is associated with the semimembranosus bursa and occurs under the medial head of the gastrocnemius muscle. It is connected directly to the joint, and it swells because of a problem in the joint and not because of bursitis. A Baker’s cyst is commonly painless, causing no discomfort or disability. Some inflamed bursae may be painful and disabling because of the swelling and should be treated accordingly.
Treatment – Management usually follows a pattern of eliminating the cause, prescribing rest, and reducing inflammation (PRICE). Perhaps the two most important techniques for controlling bursitis are the use of elastic compression wraps and anti-inflammatory medication. When the bursitis is chronic or recurrent and the synovium has thickened, the use of aspiration and a steroid injection may be warranted.

37. Runner’s Knee – Iliotibial Band Friction Syndrome
Etiology Ober’s Test Pathology Treatment
Etiology – Runner’s knee is a general term for many repetitive and overuse conditions. Many runner’s knee problems can be attributed to malalignment and structural asymmetries of the foot and lower leg, including leg-length discrepancy. Iliotibial band friction syndrome is one of the most common runner’s knee injuries. ITB friction syndrome is an overuse condition commonly occurring in runners and cyclists who have genu varum (also called bow-leggedness, bandiness, bandy-leg, and tibia vara, is a physical deformity marked by (outward) bowing of the leg in relation to the thigh, giving the appearance of an archer's bow. Usually medial angulation of both femur and tibia is involved) and pronated feet. Irritation develops at the band’s insertion and, where friction is created, over the lateral femoral condyle. Ober’s test will cause pain at the point of irritation.
Pathology – Pain over the lateral epicondyle of the femur, feeling of tightness in the lateral thigh. Inflammation may be present over the lateral aspect of the knee. Athlete may exhibit genu varum and pronated feet.
Treatment – PRICE (ice massage is very effective) and stretching. Foam roller after heating should help loosen the IT Band to reduce the amount of friction at the knee. Correction of the foot and knee alignment should be attempted if possible. NSAIDs and analgesics are helpful as well.

38. Osteochondritis Dissecans
Etiology Pathology Treatment
Etiology – Osteochondritis dissecans is a painful condition involving partial or complete separation of a piece of articular cartilage and subchondral bone. Both teenagers and adults can have this condition. The vast majority of fragments, more than 85%, occur in the lateral portion of the femoral condyle. Clinically, osteochondral detachments are seen where ever there is osteochondritis dissecans. Typically, the lesion results in normal articular cartilage with dead subchondral bone underneath separated by a layer of fibrous tissue. The exact cause of osteochondritis dissecans is unknown. It usually has a very slow onset. Possible etiological factors include the following:
Direct or indirect trauma
Association with certain familial skeletal or endocrine abnormalities.
A prominent tibial spine impinging on the medial femoral condyle.
A facet of the patella impinging on the medial femoral condyle.
Pathology – The athlete with osteochondritis dissecans complains of a knee that aches, swells recurrently, and on occasion, may catch or lock. There may be atrophy of the quadriceps muscle and point tenderness.
Treatment – For children, rest and immobilization using a cylinder cast are usually prescribed. This management affords proper resolution of the injured cartilage and normal ossification of the underlying bone. Like many other osteochondroses, osteochondritis dissecans may take as long as a year to resolve. This condition in the teenager and adult may warrant surgery such as multiple drilling in the area to stimulate healing, pinning loose fragments, or bone grafting.

39. For your Quiz Students should be able to:
Label the parts of the bones for the knee joint including the femur, tibia, patella and fibula.
Label the muscles that are involved with the knee joint.
Label the ligament and meniscal structures of the knee.
Identify the different knee assessment tests and what they are used for.
Identify the different knee injuries and conditions and be able to define them.
Identify the different bones and their respective parts on the models of the bones.