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Chapter 20: The Knee and Related Structures

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1 Chapter 20: The Knee and Related Structures

2 Complex joint that endures great amounts of trauma due to extreme amounts of stress that are regularly applied Hinge joint w/ a rotational component Stability is due primarily to ligaments, joint capsule and muscles surrounding the joint Designed for stability w/ weight bearing and mobility in locomotion

3 Knee and Related Structures
Anatomy of the Knee A. Bones i. Femur Medial Condyle Lateral Condyle Medial Epicondyle Lateral Epicondyle ii. Tibia Tibial Plateau Tibial Tuberosity Gerdy’s Tubercle Intercondylar Eminence iii. Fibula Head iv. Patella Largest seasmoid bone Located within the tendon of the quadriceps femoris

4 Knee and Related Structures
Articulations Femur and tibia Femur and patella Femur and fibula Tibia and fibula Menisci Two oval fibrocartilages that deepen the articular facets of the tibia Cushion Maintain spacing between femur and tibia

5 Knee and Related Structures
Maintain stability Medial Meniscus “C” shaped Lateral Meniscus “O” shaped Blood supply Red-red zone = peripheral 1/3 edge = good blood supply Red-white zone = middle 1/3 edge = minimal blood supply White-white zone = inner 1/3 edge = avascular = no blood

6 Knee and Related Structures
Ligaments Anterior Cruciate Ligament (ACL) Anterior medial tibia to Posterior lateral femur Prevents femur from moving posterior during wt bearing Stabilizes tibial internal rotation Main knee ligament stabilizer Posterior Cruciate Ligament (PCL) Posterior lateral tibia to Anterior medial femur Prevents hyperextension Prevents femur from moving anterior during wt bering

7 Knee and Related Structures
Medial Collateral Ligament (MCL) Medial femoral epicondyle to Medial tibial epicondyle Prevent valgus and external rotation forces Has attachment to the medial meniscus Lateral Collateral Ligament (LCL) 1. Lateral epicondyle of femur to Head of fibula

8 Knee and Related Structures
Joint Capsule Components Bursa – Synovial fluid filled pouches Reduce friction Two dozen in and around the knee Suprapatellar Prepatellar Infrapatellar Deep infrapatellar Fat pad Cushions front of the knee Separtates patellar tendon from joint capsule

9 Knee and Related Structures
Musculature Knee flexion – hamstring group Biceps femoris Semitendinosus Semimembranosus Gracilis Sartorius Gastrocnemius Popliteus plantaris

10 Knee and Related Structures
Knee Extension – Quadriceps Group Vastus Medialis Vastus Lateralis Vastus Intermedius Rectus Femoris

11 Knee and Related Structures
Nerve Supply Tibial nerve = hamstring and gastrocnemius Common peroneal nerve = proximal fibula head = contusion causes sensory and motor deficits distally Femoral nerve Blood Supply i. Popliteal artery = stem of femoral artery

12 Knee and Related Structures
Leg Alignment Deviations Predispose to injury Patellar malalignment Genu valgum Genu varum Genu recurvatum Leg-Length and Patella Discrepancies Anatomical leg length (true leg length) ASIS to Lateral Malleolus Anatomical leg length (functional leg length) Umbilicus to Medial Malleolus Girth Measurement Q-Angle Measurement 1. ASIS to Mid-patella to Tibial Tuberosity

13 Knee and Related Structures
Special Tests for Knee Joint Stability Valgus Stress Test Varus Stress Test Anterior Drawer Lachman Drawer Test Pivot Shift Test Posterior Drawer Test Posterior Sag Test McMurray’s Test Apley Compression Test Apley Distraction Test Patellar Compression, Grinding, Apprehension, Chandelier Tests










23 Functional Anatomy Movement of the knee requires flexion, extension, rotation and the arthrokinematic motions of rolling and gliding Rotational component involves the “screw home mechanism” As the knee extends it externally rotates because the medial femoral condyle is larger than the lateral Provides increased stability to the knee Popliteus “unlocks” knee allowing knee to flex

24 Capsular ligaments are taut during full extension and relaxed w/ flexion
Allows rotation to occur Deeper capsular ligaments remain taut to keep rotation in check PCL prevents excessive internal rotation, guides the knee in flexion, and acts as drag during initial glide phase of flexion ACL stops excessive internal rotation, stabilizes the knee in full extension and prevents hyperextension

25 Range of motion includes 140 degrees of motion
Limited by shortened position of hamstrings, bulk of hamstrings and extensibility of quads Patella aids knee during extension, providing a mechanical advantage Distributes compressive stress on the femur by increasing contact between patellar tendon and femur Protects patellar tendon against friction When moving from extension to flexion the patella glides laterally and further into trochlear groove

26 Kinetic Chain Directly affected by motions and forces occurring at the foot, ankle, lower leg, thigh, hip, pelvis, and spine With the kinetic chain forces must be absorbed and distributed If body is unable to manage forces, breakdown to the system occurs Knee is very susceptible to injury resulting from absorption of forces

27 Assessing the Knee Joint
Determining the mechanism of injury is critical History- Current Injury Past history Mechanism- what position was your body in? Did the knee collapse? Did you hear or feel anything? Could you move your knee immediately after injury or was it locked? Did swelling occur? Where was the pain

28 History - Recurrent or Chronic Injury
What is your major complaint? When did you first notice the condition? Is there recurrent swelling? Does the knee lock or catch? Is there severe pain? Grinding or grating? Does it ever feel like giving way? What does it feel like when ascending and descending stairs? What past treatment have you undergone?

29 Observation Walking, half squatting, going up and down stairs
Swelling, ecchymosis, Leg alignment Genu valgum and genu varum Hyperextension and hyperflexion Patella alta and baja Patella rotated inward or outward May cause a combination of problems Tibial torsion, femoral anteversion and retroversion

30 Femoral Anteversion and Retroversion
Tibial torsion An angle that measures less than 15 degrees is an indication of tibial torsion Femoral Anteversion and Retroversion Total rotation of the hip equals ~100 degrees If the hip rotates >70 degrees internally, anteversion of the hip may exist INSERT 20-9


32 Knee Symmetry or Asymmetry
Do the knees look symmetrical? Is there obvious swelling? Atrophy? Leg Length Discrepancy Anatomical or functional Anatomical differences can potentially cause problems in all weight bearing joints Functional differences can be caused by pelvic rotations or mal-alignment of the spine

33 Palpation - Bony Medial tibial plateau Medial femoral condyle
Adductor tubercle Gerdy’s tubercle Lateral tibial plateau Lateral femoral condyle Lateral epicondyle Head of fibula Tibial tuberosity Superior and inferior patella borders (base and apex) Around the periphery of the knee relaxed, in full flexion and extension

34 Palpation - Soft Tissue
Medial and lateral collateral ligaments Pes anserine Medial/lateral joint capsule Semitendinosus Semimembranosus Gastrocnemius Popliteus Biceps Femoris Vastus medialis Vastus lateralis Vastus intermedius Rectus femoris Quadriceps and patellar tendon Sartorius Medial patellar plica Anterior joint capsule Iliotibial Band Arcuate complex

35 Palpation of Swelling Intra vs. extracapsular swelling
Intracapsular may be referred to as joint effusion Swelling w/in the joint that is caused by synovial fluid and blood is a hemarthrosis Sweep maneuver Ballotable patella - sign of joint effusion Extracapsular swelling tends to localize over the injured structure May ultimately migrate down to foot and ankle

36 Special Tests for Knee Instability
Use endpoint feel to determine stability MRI may also be necessary for assessment Classification of Joint Instability Knee laxity includes both straight and rotary instability Translation (tibial translation) refers to the glide of tibial plateau relative to the femoral condyles As the damage to stabilization structures increases, laxity and translation also increase Valgus and Varus Stress Tests Used to assess the integrity of the MCL and LCL respectively Testing at 0 degrees incorporates capsular testing while testing at 30 degrees of flexion isolates the ligaments


38 Anterior Cruciate Ligament Tests
Drawer test at 90 degrees of flexion Tibia sliding forward from under the femur is considered a positive sign (ACL) Should be performed w/ knee internally and externally to test integrity of joint capsule

39 Lachman Drawer Test Will not force knee into painful flexion immediately after injury Reduces hamstring involvement At 30 degrees of flexion an attempt is made to translate the tibia anteriorly on the femur A positive test indicates damage to the ACL

40 Pivot Shift Test Used to determine anterolateral rotary instability
Position starts w/ knee extended and leg internally rotated The thigh and knee are then flexed w/ a valgus stress applied to the knee Reduction of the tibial plateau (producing a clunk) is a positive sign

41 Posterior Cruciate Ligament Tests
Posterior Drawer Test Knee is flexed at 90 degrees and a posterior force is applied to determine translation posteriorly Positive sign indicates a PCL deficient knee

42 Posterior Sag Test (Godfrey’s test)
Athlete is supine w/ both knees flexed to 90 degrees Lateral observation is required to determine extent of posterior sag while comparing bilaterally

43 Instrument Assessment of the Cruciate Ligaments
A number of devices are available to quantify AP displacement of the knee KT-2000 arthrometer, Stryker knee laxity tester and Genucom can be used to assess the knee Test can be taken pre & post-operatively and through rehab

44 Meniscal Tests McMurray’s Meniscal Test
Used to determine displaceable meniscal tear Leg is moved into flexion and extension while knee is internally and externally rotated in conjunction w/ valgus and varus stressing A positive test is found w/ clicking and popping response


46 Apley’s Compression Test
Hard downward pressure is applied w/ rotation Pain indicates a meniscal injury Apley’s Distraction Test Traction is applied w/ rotation Pain will occur if there is damage to the capsule or ligaments No pain will occur if it is meniscal

47 Girth Measurements Subjective Rating
Changes in girth can occur due to atrophy, swelling and conditioning Must use circumferential measures to determine deficits and gains during the rehabilitation process Measurements should be taken at the joint line, the level of the tibial tubercle, belly of the gastrocnemius, 2 cm above the superior border of the patella, and 8-10 cm above the joint line Subjective Rating Used to determine patient’s perception of pain, stability and functional performance

48 Functional Examination
Must assess walking, running, turning and cutting Co-contraction test, vertical jump, single leg hop tests and the duck walk Resistive strength testing Q-Angle Lines which bisects the patella relative to the ASIS and the tibial tubercle Normal angle is 10 degrees for males and 15 degrees for females Elevated angles often lead to pathological conditions associated w/ improper patella tracking

49 Palpation of the Patella
Must palpate around and under patella to determine points of pain Patella Grinding, Compression and Apprehension Tests A series of glides and compressions are performed w/ the patella to determine integrity of patellar cartilage

50 Prevention of Knee Injuries
Physical Conditioning and Rehabilitation Total body conditioning is required Strength, flexibility, cardiovascular and muscular endurance, agility, speed and balance Muscles around joint must be conditioned (flexibility and strength) to maximize stability Must avoid abnormal muscle action through flexibility In an effort to prevent injury, extensibility of hamstrings, erector spinae, groin, quadriceps and gastrocnemius is important

51 ACL Prevention Programs
Focus on strength, neuromuscular control, balance Series of different programs which address balance board training, landing strategies, plyometric training, and single leg performance Can be implemented in rehabilitation and preventative training programs Shoe Type Change in football footwear has drastically reduced the incidence of knee injuries Shoes w/ more shorter cleats does not allow foot to become fixed while still allowing for control w/ running and cutting

52 Functional and Prophylactic Knee Braces
Used to prevent and reduce severity of knee injuries Used to protect MCL, or prevent further damage to grade 1 & 2 sprains of the ACL or to protect the ACL following surgery Can be custom molded and designed to control rotational forces

53 Recognition and Management of Specific Injuries
Medial Collateral Ligament Sprain Etiology Result of severe blow or outward twist Signs and Symptoms - Grade I Little fiber tearing or stretching Stable valgus test Little or no joint effusion Some joint stiffness and point tenderness on lateral aspect Relatively normal ROM

54 Management RICE for at least 24 hours Crutches if necessary
Follow-up care will include cryokinetics w/ exercise Move from isometrics and STLR exercises to bicycle riding and isokinetics Return to play when all areas have returned to normal May require 3 weeks to recover

55 Signs and Symptoms (Grade II)
Complete tear of deep capsular ligament and partial tear of superficial layer of MCL No gross instability; laxity at 5-15 degrees of flexion Slight swelling Moderate to severe joint tightness w/ decreased ROM Pain along medial aspect of knee Management RICE for hours; crutch use until acute phase has resolved Possibly a brace or casting prior to the initiation of ROM activities Modalities 2-3 times daily for pain Gradual progression from isometrics (quad exercises) to CKC exercises; functional progression activities

56 Signs and Symptoms (Grade III)
Complete tear of supporting ligaments Complete loss of medial stability Minimum to moderate swelling Immediate pain followed by ache Loss of motion due to effusion and hamstring guarding Positive valgus stress test Management RICE Conservative non-operative versus surgical approach Limited immobilization (w/ a brace); progressive weight bearing for Rehab would be similar to Grade I & II injuries

57 Lateral Collateral Ligament Sprain
Etiology Result of a varus force, generally w/ the tibia internally rotated Direct blow is rare If severe enough damage can also occur to the cruciate ligaments, ITB, and meniscus, producing bony fragments as well Signs and Symptoms Pain and tenderness over LCL Swelling and effusion around the LCL Joint laxity w/ varus testing May cause irritation of the peroneal nerve Management Following management of MCL injuries depending on severity

58 Anterior Cruciate Ligament Sprain
Etiology MOI - tibia externally rotated and valgus force at the knee (occasionally the result of hyperextension from direct blow) May be linked to inability to decelerate valgus and rotational stresses - landing strategies Male versus female Research is quite extensive in regards to impact of femoral notch, ACL size and laxity, malalignments (Q-angle) faulty biomechanics Extrinsic factors may include, conditioning, skill acquisition, playing style, equipment, preparation time Also involves damage to other structures including meniscus, capsule, MCL

59 Signs and Symptoms Management
Experience pop w/ severe pain and disability Rapid swelling at the joint line Positive anterior drawer and Lachman’s Other ACL tests may also be positive Management RICE; use of crutches Arthroscopy may be necessary to determine extent of injury Could lead to major instability in incidence of high performance W/out surgery joint degeneration may result Age and activity may factor into surgical option Surgery may involve joint reconstruction w/ grafts (tendon), transplantation of external structures Will require brief hospital stay and 3-5 weeks of a brace Also requires 4-6 months of rehab

60 Posterior Cruciate Ligament Sprain
Etiology Most at risk during 90 degrees of flexion Fall on bent knee is most common mechanism Can also be damaged as a result of a rotational force Signs and Symptoms Feel a pop in the back of the knee Tenderness and relatively little swelling in the popliteal fossa Laxity w/ posterior sag test Management RICE Non-operative rehab of grade I and II injuries should focus on quad strength Surgical versus non-operative Surgery will require 6 weeks of immobilization in extension w/ full weight bearing on crutches ROM after 6 weeks and PRE at 4 months

61 Meniscal Lesions Etiology Signs and Symptoms
Medial meniscus is more commonly injured due to ligamentous attachments and decreased mobility Also more prone to disruption through torsional and valgus forces Most common MOI is rotary force w/ knee flexed or extended Can be longitudinal, oblique or transverse tears Signs and Symptoms Effusion developing over hour period Joint line pain and loss of motion Intermittent locking and giving way Pain w/ squatting Portions may become detached causing locking, giving way or catching w/in the joint If chronic, recurrent swelling or muscle atrophy may occur


63 Management If the knee is not locked, but indications of a tear are present further diagnostic testing may be required If locking occurs, anesthesia may be necessary to unlock the joint w/ possible arthroscopic surgery follow-up W/ surgery all efforts are made to preserve the meniscus -- will full healing being dependent on location Menisectomy rehab allows partial weight bearing and quick return to activity Repaired meniscus will require immobilization and a gradual return to activity over the course of 12 weeks

64 Osteochondral Knee Fractures
Etiology Same MOI as collateral/cruciate ligaments or meniscal injuries Twisting, sudden cutting or direct blow Signs and Symptoms Hear a snap and feeling of giving way Immediate swelling and considerable pain Management Diagnosis confirmed through arthroscopic exam, w/ surgery to replace fragment to avoid joint degeneration and arthritis

65 Osteochondritis Dissecans
Etiology Partial or complete separation of articular cartilage and subchondral bone Cause is unknown but may include blunt trauma, possible skeletal or endocrine abnormalities, prominent tibial spine impinging on medial femoral condyle, or impingement due to patellar facet Signs and Symptoms Aching pain with recurrent swelling and possible locking Possible quadriceps atrophy and point tenderness Management Rest and immobilization for children Surgery may be necessary in teenagers and adults (drilling to stimulate healing, pinning or bone grafts

66 Loose Bodies w/in the Knee
Etiology Result of repeated trauma Possibly stem from osteochondritis dissecans, meniscal fragments, synovial tissue or cruciate ligaments Signs and Symptoms May become lodged, causing locking or popping Pain and sensation of instability Management If not surgically removed it can lead to conditions causing joint degeneration

67 Joint Contusions Etiology Signs and Symptoms Management
Blow to the muscles crossing the joint (vastus medialis) Signs and Symptoms Present as knee sprain, severe pain, loss of movement and signs of acute inflammation Swelling, discoloration Possible capsular damage Management RICE initially and continue if swelling persists Gradual progression to normal activity following return of ROM and padding for protection If swelling does not resolve w/in a week a chronic condition (synovitis or bursitis) may exist requiring more rest

68 Peroneal Nerve Contusion
Etiology Compression of peroneal nerve due to a direct blow Signs and Symptoms Local pain and possible shooting nerve pain Numbness and paresthesia in cutaneous distribution of the nerve Added pressure may exacerbate condition Generally resolves quickly -- in the event it does not resolve, it could result in drop foot Management RICE and return to play once symptoms resolve and no weakness is present Padding for fibular head is necessary for a few weeks

69 Bursitis Etiology Signs and Symptoms Management
Acute, chronic or recurrent swelling Prepatellar = continued kneeling Infrapatellar = overuse of patellar tendon Signs and Symptoms Prepatellar bursitis may be localized swelling above knee that is ballotable Swelling in popliteal fossa may indicate a Baker’s cyst Associated w/ semimembranosus bursa or medial head of gastrocnemius Commonly painless and causing little disability May progress and should be treated accordingly Management Eliminate cause, RICE and NSAID’s Aspiration and steroid injection if chronic

70 Patellar Fracture Etiology Signs and Symptoms Management
Direct or indirect trauma (severe pull of tendon) Forcible contraction, falling, jumping or running Signs and Symptoms Hemorrhaging and joint effusion w/ generalized swelling Indirect fractures may cause capsular tearing, separation of bone fragments and possible quadriceps tendon tearing Little bone separation w/ direct injury Management X-ray necessary for confirmation of findings RICE and splinting if fracture suspected Refer and immobilize for 2-3 months

71 Acute Patella Subluxation or Dislocation
Etiology Deceleration w/ simultaneous cutting in opposite direction (valgus force at knee) Quad pulls the patella out of alignment Some athletes may be predisposed to injury Repetitive subluxation will impose stress to medial restraints Signs and Symptoms W/ subluxation, pain and swelling, restricted ROM, palpable tenderness over adductor tubercle Dislocations result in total loss of function

72 Management Reduction is performed by flexing hip, moving patella medially and slowly extending the knee Following reduction, immobilization for at least 4 weeks w/ use of crutches and isometric exercises during this period After immobilization period, horseshoe pad w/ elastic wrap should be used to support patella Muscle rehab focusing on muscle around the knee, thigh and hip are key (STLR’s are optimal for the knee) Possible surgery to release tight structures Improve postural and biomechanical factors

73 Chondromalacia patella
Etiology Softening and deterioration of the articular cartilage Possible abnormal patellar tracking due to genu valgum, external tibial torsion, foot pronation, femoral anteversion, patella alta, shallow femoral groove, increased Q angle, laxity of quad tendon Signs and Symptoms Pain w/ walking, running, stairs and squatting Possible recurrent swelling, grating sensation w/ flexion and extension Pain at inferior border during palpation Management Conservative measures RICE, NSAID’s, isometrics, orthotics to correct dysfunction Surgical possibilities

74 Patellofemoral Stress Syndrome
Etiology Result of lateral deviation of patella while tracking in femoral groove Tight structures, pronation, increased Q angle, insufficient medial musculature Signs and Symptoms Tenderness of lateral facet of patella and swelling associated w/ irritation of synovium Dull ache in center of knee Patellar compression will elicit pain and crepitus Apprehension when patella is forced laterally Management Correct imbalances (strength and flexibility) McConnell taping Lateral retinacular release if conservative measures fail

75 Osgood-Schlatter Disease and Larsen-Johansson Disease
Etiology Osgood Schlatter’s is an apophysitis occurring at the tibial tubercle Begins cartilagenous and develops a bony callus, enlarging the tubercle Resolves w/ aging Common cause = repeated avulsion of patellar tendon Larsen Johansson is the result of excessive pulling on the inferior pole of the patella Signs and Symptoms Both elicit swelling, hemorrhaging and gradual degeneration of the apophysis due to impaired circulation


77 Signs and Symptoms (continued)
Pain w/ kneeling, jumping and running Point tenderness Management Conservative Reduce stressful activity until union occurs (6-12 months) Possible casting, ice before and after activity Isometerics

78 Patellar Tendinitis (Jumper’s or Kicker’s Knee)
Etiology Jumping or kicking - placing tremendous stress and strain on patellar or quadriceps tendon Sudden or repetitive extension Signs and Symptoms Pain and tenderness at inferior pole of patella 3 phases - 1)pain after activity, 2)pain during and after, 3)pain during and after (possibly prolonged) and may become constant Management Ice, phonophoresis, iontophoresis, ultrasound, heat Exercise Patellar tendon bracing Transverse friction massage


80 Patellar Tendon Rupture
Etiology Sudden, powerful quad contraction Generally does not occur unless a chronic inflammatory condition persist resulting in tissue degeneration Occur primarily at point of attachment Signs and Symptoms Palpable defect, lack of knee extension Considerable swelling and pain (initially) Management Surgical repair is needed Proper conservative care of jumper’s knee can minimize chances of occurring If steroids are being used, intense knee exercise should be avoided due to weakening of collagen

81 Runner’s Knee (Cyclist’s Knee)
Etiology General expression for repetitive/overuse conditions attributed to mal-alignment and structural asymmetries Signs and Symptoms IT Band Friction Syndrome Irritation at band’s insertion - commonly seen in individual that have genu varum or pronated feet Pes Anserine Tendinitis or Bursitis Result of excessive genu valgum and weak vastus medialis Due to running w/ one leg higher than the other Management Correction of mal-alignments Ice before and after activity, proper warm-up and stretching Avoidance of aggravating activities NSAID’s and orthotics

82 Knee Joint Rehabilitation
General Body Conditioning Must be maintained with non-weight bearing activities Weight Bearing Initial crutch use, non-weight bearing Gradual progression to weight bearing while wearing rehabilitative brace Knee Joint Mobilization Used to reduce arthrofibrosis Patellar mobilization is key following surgery CPM units

83 Neuromuscular Control
Flexibility Must be regained, maintained and improved Muscular Strength Progression of isometrics, isotonic training, isokinetics and plyometrics Incorporate eccentric muscle action Open versus closed kinetic chain exercises Neuromuscular Control Loss of control is generally the result of pain and swelling Through exercise and balance equipment proprioception can be enhanced

84 Functional Progression
Bracing Variety of braces for a variety of injuries and conditions Typically worn for 3-6 weeks after surgery --used to limit ranges for a period of time Some are used to control for specific injuries while others are designed for specific forces and stability Functional Progression Gradual return to sports specific skills Progress w/ weight bearing, move into walking and running, and then onto sprinting and change of direction

85 Return to Activity Based on healing process - sufficient time for healing must be allowed Objective criteria include strength and ROM measures as well as functional performance tests

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