Sprains and Strains The Biomechanics of Injury Janus D. Butcher UMD School of Medicine June 2007.
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Transcript of Sprains and Strains The Biomechanics of Injury Janus D. Butcher UMD School of Medicine June 2007.
Sprains and Strains
• Biomechanical Model
• History and Physical
• Initial Treatment
• Rehabilitative Treatment
• Illustrative Cases/Complications
Biomechanical Model of Acute Ligament/tendon Injury
• Acute injury occurs when a ligament or tendon is subjected to tensile stress (load) that exceeds it’s tensile strength.
Biomechanical Model of Overuse Injury to Ligament or Tendon
• Overuse injury occurs when ligament or tendon is subjected to repetitive tensile stress at a frequency, duration, and intensity that exceed its capacity for recovery or repair.
Biomechanical ModelFactors That Increase Risk of Injury
• Increased tensile stress
• Decreased tensile strength
• Decrease capacity for repair
Increased Tensile Stress
• Eccentric overload
• Ballistic velocity
• Weak supporting dynamic stabilizers
• Proprioceptive deficit
Decreased Tensile Strength
• Prior injury• Disuse atrophy• Degenerative disease• Aging• Connective tissue
disease• Medications
Decreased Capacity for Repair
• Recurrent injury
• Aging
• Connective tissue disease
• Vascular disease
• Diabetes
• Smoking
• Medications
• Other
Biomechanical ModelInjury Prevention
• Decrease tensile load (stress)
• Increase tensile strength
• Enhance ability for repair
Decrease Tensile LoadExtrinsic Factors
• Proper equipment• Proper technique• Bracing/taping• Orthotics
Increase Tensile StrengthIntrinsic Factors
• Resistance exercise (eccentric loading)
• Balanced strengthening of dynamic stabilizers
• General conditioning
• Proprioception training
Sprains and StrainsMechanism of Injury
• Deformation injury produced by stress
• Musculotendinous injuries usually eccentric overload
• Ligament injuries usually non-anatomic stress
Grading Severity
• Grade 1: Micro-tears (stretch)
• Grade 2: Macrotears (partial tear)
• Grade 3: Complete disruption
Joint Stability
• Musculotendinous unit and ligaments are symbiotic in joint stability
• Static stabilizer vs. dynamic stabilizers
Functional Instability
• Not the same as joint laxity
• Frequently describes “giving out”
• Unable to do certain activities• Jump
• Pivot
• Decelerate
• Cut
Functional InstabilityPossible Causes
• Ligamentous laxity
• Motion deficit
• Strength or endurance deficit
• Proprioception issues
• Internal derangement (fracture/loose body)
Sprains and StrainsPhysical Exam
• Inspection• Swelling
• Bruising
• Pain Provocation • Motion
• Palpation
Modifiers of Endpoint
• Muscle tone• Muscle guarding• Joint effusion• Soft tissue swelling• Mechanical block• Ligamentous endpoint
Physical ExamCaveats
1. The patient will tell you what’s wrong
2. The exam may or may not be confirmatory
Initial Treatment
• P Protection• R active Rest• I intermittent Ice• C Compression• E Elevation• M anti-inflammatory Medication• M anti-inflammatory Modalities
Active RestTreatment Implications
• Stimulates healing of tissue
• Allows maintenance of general conditioning
• Prevents loss of strength in supporting structures
• Maintains joint ROM
• Addresses proprioception retraining
Active Rest
• Activity is performed in a biomechanically normal position
• Protected from abnormal motion
• No pain with activity
• No pain or swelling after activity
Rehabilitative Exercise
• Goals• Control immediate inflammatory response
• Promote normal tissue healing
• Increase tensile strength
• Address collateral joint effectors
• Maximize functional stability
Return to Sport
• Absence of pain is not appropriate end-point of treatment -Webb
• Strength >80% on normal
• ROM normal
• Proprioception normal
Return to SportBracing
• Almost everyone
• Functions• Support Joint
• Enhance proprioception
• Ensure• Appropriate fit
• Use with specified activities
Case
• 24 year old student hockey athlete slid feet first into the boards.
• He saw it coming and tried to stop his crash.
• Felt a ripping sensation in his left thigh and was unable to bear weight.
Physical Exam
• Swelling
• Bruising
• Palpable defect in the vastus lateralis
• Negative extensor lag
Treatment
• P Knee immobilizer• R Knee immobilizer/flexion block
splint• I Ice• C Ace Wrap• E Elevation• M No• M NSAIDS (Indocin)
Therapy
1. Initial rest until able to weight bear
2. Gentle stretching
3. Gradual eccentric exercise (2-4 weeks)
4. Dynamic flexibility and strengthening
5. Return to sport 4 to 8 weeks
Prevention of Myositis Ossificans
• Avoid repeat injury
• Avoid aggressive activity early
• Indocin 50mg t.i.d.
Case
• 33 year old runner sprained ankle 1 year ago.
• Was very bruised and swollen but symptoms subsided without treatment
• Now has had multiple ankle sprains over the past year and ankle feels very unstable.
Physical exam
• Inspection: Normal• Tender in the anterio-
lateral corner• Weakness in peroneus
brevis• ROM: diminished
dorsiflexion
Physical exam
• Anterior drawer/talar tilt are normal
• Proprioception: Poor balance on injured side