chapter 15 KNES 315 a
physical conditioning
*the development of a well-rounded ____________________ program is the key to injury prevention; * exercises should include flexibility and muscular strength, endurance, and power, as well as speed, agility, balance, and cardiovascular fitness; stretching exercises should focus on the quadriceps, hamstrings, gstrocnemius, IT band, and adductors; because many of these muscles contribute to knee stability, strengthening programs should also focus on knee muscle groups 269
exercises to prevent injury to the knee
A- hamstring stretch, seated position; place the leg to be stretched straight out with the opposite foot tucked toward the groin; reach toward the toes until a stretch is felt B- quadriceps stretch, prone position; push the heel toward the buttocks, and then raise the knee off the floor until tension is felt C- iliotibial band stretch, supine position; with the trunk stabilized, adduct the leg to be stretched over the other leg and allow gravity to passively stretch the iliotibial band D- Iliotibial band stretch, standing position; cross the limb to be stretched behind the other, extending and adducting the hip as far as possible E- Closed chain exercises: 1. step-ups, step-downs, and lateral step-ups 2. Squats (never below 85 to 90 degrees) 3. leg press 4. lunges F- open-chain exercises: 1. knee extension (quadriceps) 2. knee flexion (hamstrings) 270-71
possible factors influencing increased rate of anterior cruciate ligament injuries in women
INTRINSIC FACTORS ligament size and laxity intercondylar notch dimensions limb alignment (wider pelvis, femoral anteversion, genu valgum, and external tibial torsion) estrogen and estrogen receptors cruciate-dependent knee EXTRINSIC FACTORS level of skill and experience shoe-floor friction ankle prophylactic braces stylistic differences in sport palsy plant and cut straight leg landing one-step stop landing with the knee hyperextended pivoting with sudden decelration muscle strength imbalance (eccentric hamstrings strength relative to eccentric quadriceps strength), endurance, and muscle recruitment 275
bursitis
_________________ can be caused by direct trauma, overuse, infections, metabolic abnormalities, rheumatic afflictions, and neoplasms (tumors) 272
rule changes
_________________ in contact sports, particularly football, have significantly reduced injuries to the knee region; modifications in acceptable techniques that prohibit blocking at or below the knee and blocking from behind have reduced traumatic injuries; proper training methods on correct technique should continue throughout the season to ensure compliance with specific rules designed to prevent injury 269
contusions
_________________ resulting from compressive forces (i.e. a kick or falling on the knee) are common at the knee; general signs and symptoms include localized tenderness, pain, swelling, and ecchmyosis; other injuries may be obscured if swelling is extensive; for example, being kicked on the medial aspect of the tibia may appear as a ________________, when in fact the impact may have caused an avulsion fracture of the MCL or an epiphyseal injury in an adolescent; extreme point tenderness and positive findings on any of the special tests should indicate a more serious injury, and referral to a physician is indicated 271
shoe design
__________________ can also prevent injury; in field sports, shoes may have a flat-sole long-cleat, short-clear, or multicleated design; the cleats should be properly positioned under the major weight bearing joints of the foot and should not be felt through the sole of the shoe; shoes with longer irregular cleats placed at the peripheral margin of the sole with a number of smaller pointed cleats in the middle produce higher torsional resistance and are associated with a significantly higher ACL injury rate when compared with shoe models with flat cleats and screw-in cleats, or with pivot disc models; in football, a cleated shoe with a higher number of shorter, broader cleats can prevent the foot from becoming fixed to the ground, yet still allow for good traction on running and cutting maneuvers 271
straight lateral instability
__________________, or varus instability, results from medial forces that produce tension on the lateral compartment, damaging the LCL, lateral capsular ligaments, PCL, and joint structures; *this isolated injury is rare because the biceps femoris, IT band, and popliteus provide a strong stabilizing effect*; a potential mechanism for this injury can be seen in the sport of wrestling when an opponent is often between the individual's legs and is able to deliver an excessive varus force that can lead to injury sLI274
fat pad contusion signs and symptoms
____________________ include locking, catching, giving way, palpable pain on either side of the patellar tendon, and extreme pain on forced extension fpc 271
straight medial instability signs and symptoms
a grade I sprain is characterized by mild pain on the medial joint line, little to no joint effusion, and full ROM that may include some discomfort; in a grade II or III injury, the individual may be unable to fully extend the leg, and often walks on the ball of the foot, unable to keep the heel flat on the ground SMI 273
physical conditioning
because many of the muscles that move the knee also move the hip, prevention of knee injuries must focus on a _________________ program; although much debate continues as to the effectiveness of prophylactic knee braces, recent rule changes and improved shoe design have contributed significantly to a reduction of injuries at the knee 269
prepatellar bursitis
because of its position, the prepatellar bursa is the most commonly injured bursa in the knee as a result of direct blows and shearing forces pb 272
ligaments
because the shallow articular surfaces of the tibiofemoral joint contribute minimally to knee stability, the stabilizing role of the _____________________ crossing the knee is of great significance; two major ligaments of the knee are the anterior and posterior cruciate ligaments; the name cruciate is derived from the fact that the two ligaments cross each other, with anterior and posterior referring to their respective tibial attachments 265
straight lateral instability signs and symptoms
damage to the LCL follows general signs and symptoms associated with an MCL sprain (as follows); "*a grade I sprain is characterized by mild pain on the medial joint line, little to no joint effusion, and full ROM that may include some discomfort; in a grade II or III injury, the individual may be unable to fully extend the leg, and often walks on the ball of the foot, unable to keep the heel flat on the ground*" occasionally, the individual may hear or feel a pop, accompanied by sharp lateral pain; swelling is minimal because the ligament is not attached to the joint capsule; VARUS + 30 degrees instability is subtle because other structures are intact; if pain is detected on the head of the fibula, an avulsion fracture should be suspected SLI 274
patellofemoral joint motion
during knee flexion and extension movements, the patella glides in the trochlear groove, primarily in a vertical direction; tracking of the patella against the femur is dependent on the direction of the net force produced by the attached quadriceps; the vastus lateralis tends to pull the patella laterally in the direction of the muscle's action line, parallel to the femoral shaft; the IT band and lateral extensor retinaculum also exert a lateral force on the patella; although there is considerable debate as to the role of the VMO, it seems to oppose the lateral pull of the vastus lateralis, and, in doing so, keeps the patella centered in the patellofemoral groove; if the magnitude of force produced by the vastus lateralis exceeds that produced by the VMO, the patella is pulled laterally out of its groove during tracking; mistracking of the patella during knee flexion/extension can be extremely painful and lead to several chronic patellofemoral conditions 269
straight posterior instability
in __________________, the tibia is displaced posteriorly, damaging the PCL; hyperextension is the most common mechanism; however, the PCL can also be damaged during a fall on a flexed knee with the foot plantar flexed, resulting in a blow to the tibial tubercle which drives the tibia posteriorly SPI 274 DASHBOARD
straight medial instability
in ___________________, or valgus instability, lateral forces cause tension on the medial aspect of the knee, potentially damaging the MCL and posteromedial capsular ligaments, as well as the PCL SMI 273
straight anterior instability
in a __________________, the tibia is displaced anteriorly damaging the ACL; damage to the ACL commonly occurs during a cutting or turning maneuver, landing, or sudden deceleration; isolated ________________ is rare; instead, an anteromedial or anterolateral laxity usually occurs SAI 274
peroneal nerve contusion signs and symptoms
in a mild acute injury, an immediate "shocking" feeling of pain may radiate down the lateral aspect of the leg and foot; if the actual nerve is not damaged, tingling and numbness may persist for several minutes; in severe cases where the nerve is crushed, initial pain is not immediately followed by tingling or numbness; rather, as swelling increases within the nerve sheath, muscle weakness in dorsiflexion or eversion, and loss of sensation on the dorsum of the foot, particularly between the great and second toes, may progressively occur days or weeks later pnc 272
straight posterior instability signs and symptoms
in milder cases, intense pain and a sense of stretching are felt in the posterior aspect of the knee; in a total rupture, a characteristic pop or snap is felt and heard, and may be followed by autonomic symptoms of dizziness, sweating, faintness, or slight nausea; large effusion and hemarthrosis usually occur within the first 2 hours after the acute injury; knee extension is limited because of the effusion and stretching of the posterior capsule and gastrocnemius SPI 274
knee flexion and extension
in the terminal 20 degrees of knee extension, the tibia externally rotates approximately 15 degrees in what is called the screw-home mechanism; in full extension, the joint's close packed position, maximal bony contact occurs between the femur and tibia, resulting in the joint being anatomically locked; this rotation occurs because the articulating surface of the medial condyle of the femur is longer than that of the lateral condyle in this locked position, rendering motion almost completely impossible; initiation of flexion from a position of full extension requires that the knee must first be unlocked; the role of locksmit in the closed kinetic chain is provided by the popliteus, which acts to externally rotate the femur with respect to the tibia, and, in doing so, freeing the joint for motion 269
deep infrapatellar bursitis
inflammation of the deep infrapatellar bursa is usually caused by overuse and subsequent friction between the patellar tendon and structures behind it (e.g. fat pad and tibia); because this bursa lies posterior to the patellar tendon, inflammation of the bursa is often confused with Osgood-Schlatter's disease (OSD) in adolescents and patellar tendonitis in older individuals 272
pes anserine bursitis
inflammation of the pes anserine bursa typically develops from friction, but may also occur in direct trauma; it is often seen in runners, cyclists, and swimmers who are subjected to excessive valgus stress at the knee or in individuals who have tight hamstrings 273
pes anserine bursitis signs and symptoms
initial symptoms include point tenderness beneath the pes tendons (usually 2 cm below the joint line), localized swelling, and crepitation; when inflammed, contraction of the hamstring muscles, rotational movements of the tibia, and direct pressure over the bursa produce pain; inflammation of this bursa is more commonly seen in middle-aged or older overwieght women, many with osteoarthirits of the knee; in order to avoid recurrence, the individual should begin an extensive flexibility program for the hamstrings and gastrocnemius-soleus complex pab 273
femoral artery
just proximal to the knee, the main branch of the ___________ becomes the poplital artery; the popliteal artery courses through the popliteal fossa and then branches, forming the medial and lateral superior genicular, the middle genicular, and medial and lateral inferior genicular arteries that supply the knee; the superior and inferior genicular arteries intertwine with each other about the knee 268
ligamentous conditions
knee joint stability depends on a static, passive system of support from its ligaments and capsular structures; the American Academy of Orthopedic Surgeons classifies ligamentous injuries at the knee according to the functional disruption of a specific ligament, or amount of laxity and the direction of laxity 273
ligamentous conditions
ligamentous damage can result in unidirectional or multidirectional instability; a straight plane (unidirectional) instability implies instability in one of the cardinal planes; injury to the ACL or PCL results in instability in the sagittal plane, allowing for equal anterior or posterior translation (shifting) of the medial and lateral tibial plateaus on the femur; injury to the MCL and LCL leads to valgus or varus instability in the frontal plane; while unidirectional instability involves damage that results in instability to a single plane, multidirectional instability involves instability in more than one plane; while both unidirectional and multidirectional injuries can be significant injuries, the explanation that follows will focus on unidirectional instabilities 273
straight anterior instability signs and symptoms
pain can range from minimal and transient to severe and lasting; it may be described as being deep in the knee DIFFICULT TO PINPOINT, but is more often felt anterior on either side of the patellar tendon or laterally on the joint line; in about 80% of ACL injuries, individuals experience a popping, snapping, or tearing sensation, and a similar percentage note a rapid onset (i.e. usually within 3 hours) of swelling (hemarthrosis); weight bearing leads to a feeling of the knee giving way or "just not feeling right" SAI 274
rotation and passive abduction and adduction
rotational capability of the tibia with respect to the femur is maximal at approximately 90 degrees of knee flexion; a few degrees of passive abduction and adduction are permitted when the joint is positioned in the vicinity of 30 degrees of flexion 269
prepatellar bursitis signs and symptoms
swelling can occur immediately or over a 24 hour period, obscuring the visible outline of the patella; direct pressure over the bursa and passive flexion of the knee lead to considerable pain; chronic prepatellar bursitis is more common than an acute episode, and is usually the result of repeated episodes of microtrauma; the condition may remain asymptomatic, except for mild discomfort when firm pressure is applied directly over the bursa pb 272
menisci
the ______________, also known as semilunar cartilages because of their half-moon shapes, are discs of fibrocartilage firmly attached to the superior plateus of the tibia by the coronary ligaments and joint capsule; they provide several functional advantages, including absorption and dissipation of force and significantly improved congruency of the joint surfaces to even stress distribution across the joint; additionally, because 74% of the total weight of the ____________ is water, when the knee undergoes compression during weight bearing, much of the fluid is squeezed out into the joint space, providing lubrication to promote gliding of the joint structures 264
femoral nerve (L2 to L4)
the ______________- courses down the anterior aspect of the thigh adjacent to the femoral artery to supply the quadriceps group; the L2 and L3 branches of the femoral nerve also innervate the sartorius 268
Q- angle
the _______________ is defined as the angle formed between the line of resultant force produced by the quadriceps muscles and the line of the patellar tendon; one line is drawn from the middle of the patella to the anterior superior iliac spine of the ilium, and a second line is drawn from the tibial tubercule through the center of the patella; the normal _______________ ranges from approximately 13 degrees in males to 18 degrees in females, when the knee is fully extended; *a ____________ less than 13 or greater than 18 is considered abnormal, and can predispose individuals to patellar injuries or degeneration; * cadaver studies show that increasing the ______________ increases lateral patellofemoral contact pressure and could promote lateral patellar dislocation, whereas decreasing the _______________ could increase the medial tibiofemoral contact pressure; factors that contribute to an increased angle in women include a wider pelvis, increased femoral anteversion, increased knee valgus, external tibial torsion, increased ligamentous laxity, and hyperpronation of the foot 266
menisci
the ________________ also increase knee stability by serving as soft tissue restraints that resist anterior tibial displacement; in addition, the medial ______________ has an attachment to the medial collateral ligament and fibers from the semimembranous muscle; *it is injured more frequently than the lateral meniscus;* this is partly because the medial meniscus is more securely attached to the tibia, and therefore less mobile; in comparison, the lateral meniscus is a smaller and more freely movable structure 265
lateral collateral ligament (LCL)
the ________________ connects the lateral epicondyle of the femur to the head of the fibula, contributing to lateral stability of the knee; the ligament is separated from the lateral meniscus by a small fat pad; *the ______________ is the primary restraint against varus forces when the knee is between full extension and 30 degrees of flexion, and provides secondary restraint against external rotation of the tibia on the femur *265
knee
the _________________ functions primarily as a hinge joint; however, the different shapes of the femoral condyles serve to complicate joint function 268
knee
the _________________ is a complex joint that is frequently injured in participation in physical activity; during walking and running, the ____________________ moves through a considerable range of motion (ROM) while bearing loads equivalent to three or four times body weight; because the ________________ is positioned between the two longest bones in the body (i.e. femur and tibia), there is the potential for creating large, injurious torques at the joint; these factors, coupled with minimal bony stability make the knee susceptible to injury; the knee is the predominant site of injury among runners, and is one of the most frequently injured joints in sports participants 263
tibial nerve (L4, L5, and S1 to S3)
the _________________ is the largest and most medial continuation of the sciatic nerve; it innervates all of the muscles in the hamstring group except the short head of the biceps femoris, and also supplies all muscles in the calf of the leg 266
knee
the __________________ is a large synovial joint including three articulations within the joint capsule; the weight-bearing joints are the two condylar articulations of the tibiofemoral joint; the third articulation is the patellofemoral joint; the soft tissue connections of the proximal tibiofibular joint also exert a minor influence on knee motion 263
anterior cruciate ligament (ACL)
the ________________________ stretches from the anterior aspect of the intercondyloid fossa of the tibia just medial and posterior to the anterior tibial spine in a superior, posterior direction to the posterior medial surface of the lateral condyle of the femur; the _________________ is a critical stabilizer that prevents anterior translation (movement) of the tibia on a fixed femur posterior translation of the femur on a fixed tibia internal and external rotation of the tibia on the femur hyperextension of the knee 265
medial collateral ligament (MCL)
the ___________and lateral collateral ligaments are also referred to as the tibial and fibular collateral ligaments, respectively, after their distal attachments; formed by two layers, the deep fibers of the _____________ merge with the joint capsule and medial meniscus to connect the medial epicondyle of the femur to the medial tibia; the superficial layer originates from a broad band just below the adductor tubercle and is separated from the deep layer by a bursa; the two layers insert just below the pes anserinus, the common attachment of the semitendinosus, sartorius, and gracilis, thereby positioning the ligament to resist medially directed shear (i.e. valgus) and rotational forces acting on the knee 265
peroneal nerve (L4, L5, S1, S2)
the common ____________________ is the lateral branch of the sciatic nerve; it innervates the short head of the biceps femoris in the thigh; proceeding inferiorly, it passes through the popliteal fossa to wind laterally along the subcutaneosu surface to just below the proximal head of the fibula, where it can be easily damaged; as it passes between the fibula and the peroneus longus muscle, it dubdivides into the superficial and deep peronal nerves 267-8
peroneal nerve contusion
the common peroneal nerve leaves the popliteal space and winds around the fibular neck to supply motor and sensory function to the anterior and lateral compartments of the lower leg; a kick of blow to the posteriolateral aspect of the knee can contuse this nerve, leading to temporary or permanent paralysis; *the nerve may also be injured by prolonged compression from a knee brace or elastic wrap, prolonged squatting (e.g. baseball or softball catcher), or by traction because of a varus stress or hyperextension at the knee* pnc 272
tibiofemoral joint
the distal femur and proximal tibia articulate to form two side-by-site condyloid joints collectively known as the ____________________-; these joints function together primarily as a modified hinge joint; because of the restricting ligaments, some lateral and rotational motions are allowed at the knee; the medial and lateral condyles of the femur differ somewhat in size, shape, and orientation; as a result, the tibia rotates laterally on the femur during the last few degrees of extension to produce locking of the knee; this phenomenon, known as the screw-home mechanism, brings the knee into the close packed position of full extension 263
ligamentous condition management
the immediate management for a suspected ligament injury involves standard acute care with cold and compression; if the individual is unable to walk normally, crutches should be used; the individual should be referred to a qualified healthcare practitioner for a definitive diagnosis and ongoing treatment options; it is important to note that the initial symptoms associated with a ligament injury could resolve within a week, including the ability to walk with a normal gait; however, the change in symptoms is not an accurate indicator of the severity of the injury; while ligament injuries do not typically warrant a visit to the emergency room, they should be seen by an orthopedic physician as soon as possible (i.e. 1 to 2 days postinjury) 276
fat pad contusion management
the immediate management includes standard acute care with cold and compression; participation in sport and physical activity is usually not limited but the area should be protected to prevent further insult; if the signs and symptoms do not resolve within 2 to 3 days, the coach should require the individual to obtain approval for return to participation from a qualified healthcare professional fpc 272
fat pad contusion
the infrapatellar fat pad may become entraped between the femur and tibia, or inflamed during arthroscopy, leading to a tender, puffy, ________________ fpc 271
bursae
the joint capsule at the knee is large and lax, encompassing both the tibiofemoral and patellofemoral joints; anteriorly, it extends above the patella to attach to the edges of the superior patella surface; the deep _________________ formed by this capsule above the patella, the suprapatellar ________________, is the largest _____________- in the body; it lies between the femur and quadriceps femoris tendon and it reduces friction between the two structures; 265 posteriorly, the SUBPOPLITEAL BURSA lies between the lateral condyle of the femur and popliteal muscle, and the SEMIMEMBRANOUS BURSA lies between the medial head of the gastrocnemius and semimembranous tendons 265
patellofemoral joint
the patella (kneecap) is a triangular bone that rests between the femoral condyles to form the ____________________; the posterior surface of the patella is composed of three distinct facets, although the number, size, and shape of these facets vary from person to person; because of its location, the patella provides some protection for the anterior aspect of the knee; in addition, the patella serves to increase the angle of pull of the patellar tendon on the tibia and, in doing so, improves the mechanical advantage of the quadriceps muscle to produce knee extension 266
knee flexion and extension
the primary motions permitted at the tibiofemoral joint are flexion and extension; *knee flexion is performed primarily by the hamstrings and assisted by the popliteus, gastrocnemius, gracilis, and sartorius*; in addition, the flexor musculature has a secondary responsibility of rotating the tibia; the flexors attaching on the tibia's medial side (i.e. semitendinous, semimembranous, gracilis, and sartorius) internally rotate the tibia, while those attaching on the lateral side (i.e. biceps femoris) externally rotate the tibia; *knee extension is carried out by the quadriceps femoris muscle group*; although the name implies four muscles, most clinicians describe five, namely the vastus lateralis, vastus intermedius, vastus medialis (VM), vastus medialis oblique (VMO), and rectus femoris; each muscle has a common attachment on the tibial tubercle via the patella and infrapatellar ligament 269
straight anterior instability
the rate of ACL injuries is higher in women, particulalry for those in jumping and pivoting sports; several theories have been put forth to explain this phenomenon; recent research has begun to look at muscle strength imbalance between the hamstrings and quadriceps in both men and women; during a landing/decelration maneuver, flexion moments are occurring at the hip and knee; simultaneous eccentric contractions of the quadriceps to stabilize the knee and hamstrings to stabilize the hip decelerate the horizontal velocity of the body; the hamstrings also act to neutralize the tendency of the quadriceps to cause anterior tibial translation; if the muscles are unable to meet the demand of stabilization, inert internal tissues, such as ligaments, cartilage, and bone, are at risk for injury; therefore, a deficit in eccentric hamstring strength relative to eccentric quadriceps strength could predispose an individual to an ACL injury; prophylactic bracing has not been shown to prevent ACL injuries SAI 274
posterior cruciate ligament (PCL)
the shorter and stronger ______________- runs from the posterior aspect of the tibial intercondyloid fossa in a superior, anterior direction to the lateral anterior medial condyle of the femur; the ___________________ is *considered to be the primary stabilizer of the knee* and resists posterior displacement of the tibia on a fixed femur 265
deep infrapatellar bursitis signs and symptoms
this condition is associated with swelling and pain in the distal patellar tendon region; in addition, knee flexion produces pain deep to the patellar tendon dib 272
bursae
three other key ________________ associated with the knee, but *not contained in the joint capsule*, are the prepatellar, superficial infrapatellar, and deep infrapatellar bursae; the prepatellar bursa is located between the skin and anterior surface of the patella, allowing free movement of the skin over the patella during flexion and extension; the superficial infrapatellar bursa is located over the patella during flexion and extension; the superficial infrapatellar bursa is located between the skin and patellar tendon; the deep infrapatellar bursa is located between the tibial tubercle and he infrapatellar tendon and is separated from the joint cavity by the infrapatellar fat pad; this bursa reduces friction between the ligament and bony tubercle 265
bursitis management
treatment consists of application of cold, a compressive wrap, NSAIDs, avoiding activities that irritate the condition, or total rest until acute symptoms subside; a protective foam, or doughnut pad, may protect the area from further insult; there is a risk of infection if the skin is broken during the initial injury, in which case, the individual should be referred to a physician immediately; the physician may culture any aspirated fluid to detect bacteria and subsequently prescribe medication 273
peroneal nerve contusion management
treatment involves standard acute care for contusions; however, caution should be exercised in applying a compression wrap, as the position of the wrap could further compress the nerve; if the condition does not rapidly improve or the individual experiences sensory or motor deficits, immediate referral to a physician is warranted pnc 272
