BIOMECHANICS AND SPORTS MEDICINE

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BIOMECHANICS AND SPORTS MEDICINE
By Will Dang, Claudine Dizon, Daniel Hidalgo,
and Gina Cuevas
KNES 461 Biomechanical Analysis of Human
Movement Sept 8th, 2004 Dr. Guillermo Noffal
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INTRODUCTION

• Biomechanics is a major factor in the field of
  sports medicine
• Whether it is describing the mechanism of a
  sports injury, determining the amount of force
  certain tissue can withstand during a surgical
  procedure, or prescribing a correct
  rehabilitation method,
• 
  biomechanics plays a major role for sports
  medicine specialists.

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INTRODUCTION (contd)

• Because the sports medicine field is so vast, it
  is difficult to encompass all the facets of such
  a major realm of science.
• Thus, it is the focus of this group to touch on
  certain elements of sports medicine as it
  pertains to biomechanics, i.e. common injuries
  found in the domain of sports medicine

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WHAT IS BIOMECHANICS?

• The applications of mechanical principles to
  biological problems.
• Mechanism Physical process responsible for a
  given action, reaction, or result

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APPLICATION TO SPORTS MED???

• Sports Medicine is the branch of medicine
  concerned with physical fitness and with the
  treatment and prevention of injuries and other
  disorders related to sports.
• Obviously, biomechanics can be linked to almost
  all forms of sports medicine

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ACL BIOMECHANICS

• ACL is primary restraint to anterior translation
  of the tibia
• ACL is secondary restraint to tibial rotation and
  varus/valgus loading at full extension
• Average tensile strength for ACL is 2160N

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ACL Injury Mechanism

• Valgus loading and external tibial rotation
  (cutting movements)
• Hyperextension and internal tibial rotation
  (landing from jumps/rotate)
• Load exceeds tissue capabilities

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Arthroscopic ACL Reconstruction Surgery
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The most common type of tendon graft for an ACL
surgery is the middle one-third of the patella
tendon with a bone block at each end.
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Holes are then drilled through the tibia and
femur. These holes are located at the attachment
sites of the original ligament.
The graft is then pulled through the holes and
set in place by screws.
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• By fastening the graft in this way new blood
  vessels are allowed to grow around the attachment
  sites, thus facilitating the healing process.
• Because arthroscopy is used in this surgery
  it is typically performed on an outpatient basis.
• Arthroscopy typically allows athletes to
  recover more quickly so they can return to their
  sport or activity.

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ACL Rehabilitation Goals

• Restoration of joint anatomy
• Providing static and dynamic stability
• Return to normal activities

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Accelerated RehabilitationPhase 1

• Patient is placed on a CPM machine before they
  awake in the operating room.
• Next day the brace is put on locked in extension,
  crutches optional

• Patient remains home for the first 7 days using
  the CPM machine for 23 hours a day.
• By the end of week patient should have full
  extension and 90 degree flexion

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Phase 1 Goals

• Protective reconstruction and avoid falling
• Ensure wound healing
• Attain and maintain full knee flexion
• Promote Quadriceps muscle strength

• Gain knee flexion to near 90 degrees
• Decrease knee and leg swelling by avoiding blood
  pooling in leg veins
• Prescribed exercises will help assist in
  accomplishing goals

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Phase 1 Goals

• Protective reconstruction and avoid falling
• Ensure wound healing
• Attain and maintain full knee flexion
• Promote Quadriceps muscle strength

• Gain knee flexion to near 90 degrees
• Decrease knee and leg swelling by avoiding blood
  pooling in leg veins
• Prescribed exercises will help assist in
  accomplishing goals

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Phase 21-5 weeks

• Patient returns for examination to check status
  of knee
• Patient is given shorter postoperative brace
• Patient is encouraged to test knee with full
  weight barring

• Patient is encouraged to use brace for means of
  support and comfort
• Prescribed exercises done twice a day
• Patient should achieve gait independently between
  3-5 weeks post surgery

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Phase 2 Goals

• Protect the reconstruction and avoid falling
• Ensure wound healing
• Maintain full knee extension
• Begin quad muscle strengthening

• Attain knee flexion of 90 degrees or more
• Decrease knee and leg swelling
• Normal Gait without crutches or brace

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Phase 33-9 weeks after surgery

• Swimming may begin at this time (standard
  freestyle kick)
• phase 1 exercises can be disregarded and strength
  in quadriceps are efficient
• Resistance using ankle weights may be added

• Development of single leg strength is emphasized
  at this time
• Quadriceps strengthening should continue for full
  active knee extension
• Optional regiment of weight room exercises

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Goals of Phase 3

• Protect the reconstruction avoid falling
• Maintain full knee extension
• Attain full knee flexion
• Walk with normal heel to gait with no limp

• Muscle strength and conditioning improvements

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Phase 4 Goals

• Full muscle strength
• Improve cardiovascular conditioning
• Sports specific training
• Straight ahead phase
• Direction phase

• Advanced direction change and impact phase
• Sport specific phase

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Phase 4

• Patient is allowed to use stationary bike and or
  swimming
• Orderly sequenced of drills designed to attain
  the proprioceptive feedback loops

• Neuromuscular control of operated knee
• Logical sequence of progressive drills for pre
  sports conditioning is to provide an objective
  criteria for patients safe return to sport

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FOR MORE INFO...
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ROTATOR CUFF BIOMECHANICS

• Primary source of stability to the shoulder
• Associated with and assist with some shoulder
  motion such as external rotation, internal
  rotation, abduction, adduction, and to some
  degree, extension
• Principle function, however, is to stabilize the
  GH joint

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ROTARY CUFF INJURY

• Impingements
• extrinsic structural factors
• hook acromion
• hypertrophy of supraspinatus
• Intrinsic
• inflammation of the tissue
• Mechanism
• overuse in sports requiring overhead movements
• abductor dominance (wheelchair)

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ROTARY CUFF INJURY (contd)

• Rotator Cuff Tear
• Chain of events
• Inflammation
• Microtears
• Partial or total rupture
• Movement adaptations
• Supraspinatus most common
• Eccentric Actions
• Acceleration phase
• Deceleration phase

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Tensile Failure

• -Failure with throwing
• -Throwing motion (5) phases
• 1.wind-up
• 2.cocking
• 3.acceleration
• 4.deceleration
• 5.follow-through
• -Forces generated during these phases result in
  stress around the shoulder joint causing prone to
  acute and chronic inflammatory conditions and
  injuries.

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KINEMATIC PATTERNS RELATED TO ROTATOR CUFF TEAR
LOCATION
Kinematic Pattern Tear Location
I. Stable fulcrum kinematics Supraspinatus part of infraspinatus
II. Unstable fulcrum kinematics (posterior cuff tear pattern) Supraspinatus all of posterior cuff (infraspinatus teres minor)
III. Captured fulcrum kinematics Supraspinatus major posterior cuff at least 50 subscapularis
IV. Unstable fulcrum kinematics (subscapularis tear pattern) Supraspinatus complete subscapularis
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• Rotator Cuff Surgery Options
• Arthroscopic Rotator Cuff Repair
• Least invasive of all surgical options
• Small, 1-centimeter incisions leave less scarring
  and allow quicker healing with less pain
• Less scar tissue develops so range of motion is
  not restricted and less rehab is needed
• Surgeon inserts a tiny camera into the incision
  and watches on a television monitor
• Cause minimal trauma to the tissues that surround
  the shoulder and the rotator cuff (deltoid)
• Most difficult of the three procedures listed

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Left Stitches are used to close the large tear.
Right Metallic anchors are set into the humerus
at the site for tendon reattachment.
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• Open Rotator Cuff Repair
• Now only used in the most severe cases
• Most invasive of the three methods in which a
  6-10 centimeter incision is made
• Muscle beneath the skin is separated to expose
  the damaged rotator cuff
• The surgical dissection can potentially cause
  pain and disability, despite a good rotator cuff
  repair
• Usually leads to more scarring than the less
  invasive procedures
• Not popular in treating professional athletes
  because of extended post-surgery recovery and
  therapy time that is needed

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• Mini-open Rotator Cuff Repair
• Combination of arthroscopy and a small incision
  (approx. 3-5 centimeters)
• Currently the most popular rotator cuff repair
  procedure because it is highly successful and
  less invasive than open surgery.
• Allows more necessary repairs to be done around
  the rotator cuff than the all-arthroscopic
  procedure.

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• Surgery is the final option for most but is more
  readily used with professional athletes because
  non-operative therapy can take too long and the
  rotator cuff may never fully heal
• Other damage to the shoulder that is found during
  surgery is usually repaired at this time (e.g.,
  bone spurs on the underside of the acromion bone
  are common in those suffering from rotator cuff
  tears.)

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Good throwing technique

• Requires the athlete to use his body weight and
  the large muscle groups of the legs, back and
  trunk to generate kinetic energy across the
  shoulder in the direction of the thrown object.

Poor mechanics during the wind-up and cocking
phase require the shoulder muscles to generate
more required energy to throw the object, which
then leads to fatigue of the shoulder muscles,
resulting in injuries.
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Note

• A great deal of the force generated in overhead
  sports occurs in the trunk and lower extremity,
  and these areas should be targeted in any
  conditioning program for athletes who throw.

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Example

•   Wind-up rotator cuff muscles are inactive
  during this initial stage.
•   Early cocking stage involves external
  shoulder rotation.
•   Late cocking stage the rotator cuff muscles
  are very active during this stage, especially the
  subscapularis, which contracts and acts as a
  dynamic stabilizer
•   Acceleration stage begins with internal
  rotation of the humerus and ends with release of
  the baseball. The muscles of the rotator cuff are
  basically inactive.
•   Follow-through during this phase, the
  rotator cuff muscles are most active. The
  supraspinatus contracts to decelerate internal
  rotation of the limb.

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Rehabilitation of Rotator Cuff Injuries

• -Requires reduction of any inflammation.
• -Soft tissue massage, stretching and
  strengthening.
• -Specific bungy and free weight exercises in
  functional ranges of motion.

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WHO USES BIOMECHANICS IN SPORTS MEDICINE???

• Orthopedic Surgeons
• Education
• 4 years of undergrad
• 4 years of medical school
• Usually 4 years of residency
• 1-2 years of fellowship
• After that is all said and done though, The
  median expected salary for a typical Physician -
  Surgery - Orthopedic in Orange County, CA, is a
  whopping
• 332,288

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WHO USES BIOMECHANICS IN SPORTS MEDICINE???
(contd)

• Physical therapists
• Dr George Young Interview
• PT at Alamitos Physical Therapy
• Graduated with bachelors in biology
• Taught high school biology and coached tennis and
  softball

• Worked in the physiology department at USC while
  taking classes
• Physical therapy masters in 2 years at USC
• Started his own business

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Dr. George Young Interview

• After 8 years with his own practice went back for
  Doctorate
• Has friends who have succeeded and some that went
  bankrupt with their own practice

• New grad can start off making 25 an hour
• Depends on location and demand
• Downtown New York a new grad can start off
  making 6 figures