BIOMECHANICS AND SPORTS MEDICINE

1. 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

2. 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.

3. INTRODUCTION (cont’d) • 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

4. WHAT IS BIOMECHANICS? • The applications of mechanical principles to biological problems. • Mechanism: Physical process responsible for a given action, reaction, or result

5. 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

7. 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

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

10. Arthroscopic ACL Reconstruction Surgery

11. 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.

12. 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.

13. 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.

14. ACL Rehabilitation Goals • Restoration of joint anatomy • Providing static and dynamic stability • Return to normal activities

15. 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 Accelerated RehabilitationPhase 1

16. 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 Phase 1 Goals

17. 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 Phase 1 Goals

18. 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 Phase 21-5 weeks

19. 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 Phase 2 Goals

20. 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 Phase 33-9 weeks after surgery

21. 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 Goals of Phase 3

22. Full muscle strength Improve cardiovascular conditioning Sports specific training Straight ahead phase Direction phase Advanced direction change and impact phase Sport specific phase Phase 4 Goals

23. 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 Phase 4

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25. 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

28. 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)

29. ROTARY CUFF INJURY (cont’d) • Rotator Cuff Tear • Chain of events • Inflammation • Microtears • Partial or total rupture • Movement adaptations • Supraspinatus most common • Eccentric Actions • Acceleration phase • Deceleration phase

30. 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.

31. KINEMATIC PATTERNS RELATED TO ROTATOR CUFF TEAR LOCATION

32. 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

33. Left: Stitches are used to close the large tear. Right: Metallic anchors are set into the humerus at the site for tendon reattachment.

34. 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

35. 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.

36. 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.)

37. 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.

38. 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.

39. 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.

41. 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.

42. 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

43. 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 WHO USES BIOMECHANICS IN SPORTS MEDICINE??? (cont’d)

44. 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 Dr. George Young Interview