chapter
23
Knee and Thigh
The Knee
• The knee is one of the most frequently injured
joints in athletics.
• The forces applied to it during sport activities
are complicated by the fact that there are two
long lever arms on either end of the joint,
making it a joint that is susceptible to injury.
• Stability comes from ligaments and muscles.
Knee Structure
• Two joints: tibiofemoral joint and patellofemoral (PF)
joint
• Capsule: resting = 20°-25° flexion; closed = full
extension, external rotation (ER)
• Ligaments: medial collateral (MCL), lateral collateral
(LCL), anterior cruciate (ACL), posterior cruciate (PCL)
– MCL: restricts valgus stresses, ER
– LCL: restricts varus stresses, internal rotation (IR)
– ACL, PCL: restrict AP stresses; taut during IR
(continued)
Knee Structure (continued)
• Neuroreceptors: in capsule, ligaments
• 1° stability: ligaments; 2°= capsule, muscles
• Medial/lateral meniscus: fibrocartilage screw
home mechanism: flexion  extension
WB: IR femur
NWB: ER tibia
• Muscles: quadriceps and hamstring groups,
popliteus
Patellofemoral Joint
• Resting position: full extension
• Closed position: knee flexion
• Patella must glide freely for full knee motion to
occur
• Patella excursion is 5-7 cm
• Inferior pole of patella lies at tibiofemoral joint
margin
• Contact between femur and patella changes
through range of motion (ROM)
(continued)
Patellofemoral Joint (continued)
• Joint reaction force: compressive force = PF
quadriceps muscle and tendon resultant vector
force
• Contact pressure: ratio between PF joint
reaction force and contact area
• In closed kinetic chain, as knee flexes, contact
area and compressive force increase
• Force  is greater than surface , so
compression increases in WB with ROM
increases
Figure 23.1
PF Compressive Forces
• Greatest patellofemoral compressive forces
occur in 60°-90° positions.
• Closed kinetic chain (CKC): 0° to 30°
produces minimal PF stress.
• Open kinetic chain (OKC): <20° (without
weights) produces minimal PF stress.
(continued)
PF Compressive Forces (continued)
•
Distally attached cuff weights produce
maximum patellofemoral compressive forces
at 35°-45°.
•
Greatest tibiofemoral shear force: 15°-30°.
•
Machine resistance applied at the ankle
reaches maximum patellofemoral compressive
forces at 90°.
Figure 23.4
Patellar Malalignments
• Patella alta: patella higher than its normal
position in the patellofemoral groove
• Patella baja: patella lower than its normal
position in the patellofemoral groove
Q-Angle
• = The angle that is formed by a line from the
anterior superior iliac spine (ASIS) to the
middle patella and a line from the middle
patella to the tibial tubercle
• Normal Q-angle 10°-15°
• Can change from weight bearing to non-weight
bearing
• Disputable evidence that it is larger in women
because of pelvic structure
• Pronation or a weak vastus medialis oblique
(VMO) can increase the Q-angle
Figure 23.2
Leg Alignment
• Excessive rearfoot pronation influences the
patella’s alignment.
• Since the lower extremity works as a CKC
during most functions, malalignment in one
segment affects or causes compensatory
changes in another segment.
Factors Affecting Postinjury Strength
• Edema: inhibits quadriceps function
• Pain: causes reflex withdrawal inhibition
• Antalgic gait: causes weakness throughout
lower extremity
Rehabilitation Concepts
• Extensor lag: in presence of full passive knee
extension, incomplete active knee extension is
secondary to quadriceps weakness.
• Quadriceps force required for last 15° of
extension is twice as great as for other ranges
of motion because of the muscle’s reduced
mechanical and physiological advantage.
(continued)
Rehabilitation Concepts (continued)
• ACL stress in weight bearing is at least 0°60°
0-60°
• ACL stress in non-weight bearing is greatest at
30°-60° and least at 60°-90°
60-90°
Figure 23.3
Knee Bracing
• ACL braces provide stability during low-stress
loads but not during functional loads.
• Knee braces may provide proprioceptive
feedback.
• Types: prophylactic for prevention,
rehabilitative for protection, functional for
stability
• Custom and off-the-shelf
Therex Progression
• Dictated by tissue healing and response to
exercise stress
• Range of motion via exercise, joint mobilization,
soft-tissue mobilization
• Strength exercises with low-level resistance
initially
(continued)
Therex Progression (continued)
• Balance with bilateral support, progressing to
unilateral static and then dynamic activities
• Agility activities
• Functional activities
• Sport- and activity-specific exercises
Soft-Tissue Mobilizations
• Massage for edema, spasm
• Deep-tissue releases for adhesions
• Foam roller on tensor fascia latae (TFL),
quadriceps or deep-tissue massage
• Trigger point releases:
– Quadriceps: patella from rectus femoris or vastus
medialis
– Popliteus: posterior knee pain
– TFL: lateral thigh
Figure 23.5a1
Figure 23.5a2
Figure 23.5a3
Figure 23.5a4
Figure 23.5b1
Figure 23.5b2
Figure 23.5b3
Figure 23.7a
Figure 23.7b1
Figure 23.7b2
Figure 23.7c
Figure 23.10
Figure 23.11
Figure 23.12
Figure 23.13a
Figure 23.13b
Figure 23.13c
Figure 23.13d
Figure 23.14
Figure 23.15
Figure 23.16
Figure 23.17
Figure 23.18
Flexibility
•
•
•
•
Short-term: active versus passive
Prolonged
Age of scar tissue
Continuous passive motion (CPM) machines
immediately following surgical repair
Figure 23.19
Figure 23.20
Figure 23.22
Figure 23.23
Figure 23.25
Figure 23.26
Figure 23.27
Strength
• Can begin early even if knee is immobilized and
non-weight bearing.
• Exercises for trunk, hip, and ankle should be
included.
• Pain or swelling should not occur during or after
exercise.
• Add exercises judiciously so can identify cause
of inflammatory response.
Figure 23.28
Figure 23.33
Figure 23.35
Figure 23.39
Figure 23.40
Figure 23.41
Figure 23.43
Figure 23.44
Proprioception and Functional Activities
• Program includes proprioceptive exercises
aimed at restoring balance, agility, and
coordination.
– See figure 23.46a-c.
• Functional exercises for the knee, which are
similar to those for the hip and ankle, use
hopping, running, and cutting as well as sportspecific drill and skill activities.
Figure 23.46a
Figure 23.46b
Figure 23.46c
Figure 23.47a
Figure 23.47b
Injury: Sprain
• Swelling occurs in 2-24 h
• ACL reconstruction: patellar tendon or
hamstring graft
• Delayed versus accelerated rehab
• Strong gastrocnemius contraction avoided
beyond 30° flexion in PCL sprains
• MCL injuries rarely surgically repaired
• Avoid patellofemoral pain
ACL Reconstruction
• Rehabilitation considerations
– Patient age
– Weight-bearing status
– Source of graft
• Must always keep in mind healing and maturity
of graft
Meniscal Injuries
• Isolated meniscal tears are more likely to be
degenerative.
• Lateral meniscal repairs have a better success
rate than medial repairs.
• In the long run, meniscal repair is more
beneficial than meniscectomy.
• Conservative versus accelerated rehab
Figure 23.49
Meniscal Repair
•
•
•
•
Arthroscopic procedure
Weight bearing is partial initially
Avoid stressing meniscus in area of repair.
Communication with surgeon is vital.
Patellar Injuries
•
•
•
•
Patellar dislocations and subluxation
Patella plica syndrome
Osgood-Schlatter disease
Patellar tendinitis patellofemoral stress
syndrome = PFSS (PFPS)
• Tendon rupture
Patellar Dislocation
•
•
•
•
Extreme pain, edema
Disability prolonged if swelling is excessive
Quadriceps strengthening important
Inability to walk without assistive devices until
full active knee extension is possible and
patient ambulates without limping
PFPS
•
•
•
•
Must identify and correct causative factors
Must relieve muscle imbalances
Effects of foot, hip, trunk
Evaluate patellar alignment and tracking in
weight bearing and non-weight bearing
• McConnell taping effective in relieving pain
Figure 23.50a
Figure 23.50b
Figure 23.50c
Figure 23.50d
Figure 23.50e
Figure 23.50f
Figure 23.51
Figure 23.52
Figure 23.53
Figure 23.54
Strains and Contusions
• Hamstring strains—hamstring tightness often a
predisposing factor
• Quadriceps strains—often due to jumping or
sudden changes in direction
• Quadriceps contusions—first goal is to resolve
pain and spasm and maintain flexibility
(continued)
Strains and Contusions (continued)
• Myositis ossificans: causes non-neoplastic
bone formation in the muscle
• Iliotibial band (ITB) syndrome:
– Overuse syndrome in middle- and long-distance
runners
– Pain at 30° knee flexion when ITB is pulled over
the lateral femoral epicondyle
Fractures
• Patella fracture: often result of a direct blow
• Tibial fracture: often due to torsion or
compression forces
• Epiphyseal plate injuries of the proximal tibia or
distal femur
− Occur in adolescents whose growth plates have not
yet matured
− Can alter bone growth
Osteochondritis Dissecans
• Unknown etiology
• Affects femoral epiphysis in juveniles, femoral
condyle in adults
• Bone flake in juvenile osteochondritis dissecans
(OD), bone fragment in adult OD
• Knee pain, tenderness, quadriceps atrophy;
catching, locking, or giving way
• Treatment and rehabilitation