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5/7/2014 Disclosure Understanding and Writing the Lower Limb Orthotic Prescription • Mr. Jennings is currently employed by Hanger Clinic, a for-profit orthotic and prosthetic company. He is currently practicing as an Orthotist/Prosthetist and is the Area Clinic Manager in Houston, TX. Jason M Jennings, CPO Area Clinic Manager, Hanger Clinic, Houston, TX Carolyn P Da Silva, PT, DSc, NCS Associate Professor, Texas Woman’s University, Houston, TX Basic Biomechanics for Orthotic Intervention Learning Objectives The learner will: • • • • • • 1. Understand basic biomechanics of normal and pathological gait. 2. Understand principles of orthotic intervention to improve gait and function of patients/clients with neurological conditions. 3. Utilize gait and orthotic knowledge to formulate descriptive lower limb orthotic prescriptions. Review of Terminology Basic Biomechanical Principles Normal Gait Pathological Gait Pathological Gait Assessment Goals of Orthotic Treatment Review of Terminology • Biomechanics – The branch of science that studies the structure and function of the body • Ground Reaction Force (GRF) – A force exerted by the ground that is equal and opposite in direction to the force being exerted on it by an object • Ground Reaction Vector – The result of two or more GRFs. We need to start looking at these forces in 3 dimensions, as a combination of forces from the sagittal, coronal, and transverse planes • Sagittal plane – Anterior/posterior axis • Coronal plane – Medial/lateral axis • Transverse plane – Vertical axis REVIEW OF TERMINOLOGY 5 6 1 5/7/2014 Review of Terminology Review of Terminology: ROM • Passive ROM • Vertical Alignment Line – The angular movement applied to a joint by another person – The alignment of two random points in a plane by a vertical or plumb line • Functional ROM • Shank to Vertical Angle – The angular movement of a joint caused by the subjects’ applied muscle force – It may be limited due to weakness, spasticity, contracture or bony abnormality. – The angle of the shank as it relates to the vertical • Anterior crest of the tibia Owen • Common practice in US to use midline of the leg • What standard should we use? • Tardieu Scale • Initial end range or first catch (functional range during activity) – Patterning of the limb during weight bearing – R2 ROM • Secondary Patterning – Patterning of the limb during swing Haugh 2006 – R1 ROM • Primary Patterning • Maximum passive end range with torque applied 7 Review of Terminology: AFO Footwear Combination (AFOFC) • Heel sole differential – Difference in thickness between the heel height and sole height • Casting block height – The amount of block or wedge necessary to accommodate the heel sole differential, angle of contracture at the ankle, and/or knee to place the shank in the desired amount of inclination or reclination Basic Biomechanical Principles - Kinetics • Kinetic Chain – Combination of several joints uniting successive limb segments – Open: Distal segment of the chain moves in space (Swing Phase) – Closed: Distal segment is fixed, with proximal parts moving over it (Stance Phase) BASIC BIOMECHANICAL PRINCIPLES Importance of Kinetics in Orthotic Design • The assessment of the point in stance or swing phase that a problem occurs will influence your choice of orthotic design. • Open kinetic chain problems require much less rigid devices. • Closed kinetic chain problems must be able to resist the tri-planar forces that occur thru the subtalar joint under full weight bearing. Steindler, 1955 2 5/7/2014 Normal Gait • Each limb blends the patterns of motion, passive force, and muscle control into a sequence of activity (called a gait cycle or a stride), which is repeated until the desired destination is reached. The head, neck, trunk and pelvis are self contained passengers riding on the limb’s locomotor system. Perry J, et. al.. Gait Analysis, Slack 1992 NORMAL GAIT Normal Gait • Four Basic Functions are Necessary for Normal Gait – Weight Bearing Stability – Stance Limb Progression – Shock Absorption – Energy Conservation Perry 1992 Normal Gait • Weight Bearing Stability – Muscles around hip, knee and ankle sequentially stabilize these joints as body weight is transferred to the stance limb. – The pattern of muscle control is dictated by the changing alignment of the body weight line (vector) to the individual joint. – As the vector moves away from the joint center, a rotational force or moment develops that must be controlled by opposing muscles to preserve postural stability. Perry 1992 Normal Gait • Stance Limb Progression – To advance the weight bearing limb over the supporting foot, three rockers are used. A fourth rocker initiates swing limb advancement – This can be useful in visualizing the impact an orthosis will have on the patient during stance phase. Perry 1992 Normal Gait • Shock Absorption – The rapid transfer of body weight to the limb is dissipated by knee flexion redirecting the force to the quadriceps and is initiated at heel rocker Perry 1992 3 5/7/2014 Normal Gait • Energy Conservation – The selective relaxation of muscles when momentum and passive positioning can substitute; conserves energy – Co-contraction of antagonists is rare. PATHOLOGIC GAIT Perry 1992 Pathological Gait • Many types of disease and injury impair a patient’s ability to walk. • Patients develop compensations or substitutions. • This results in an increase in the energy cost of walking. • When physiologic effort or pain exceed tolerance, the disability becomes visible. Pathological Gait • As we look at pathological gait, we must remember that we are looking at a combination of cause and effect. Perry 1992 Pathological Gait • Pathological Patterns/Functional Categories: – Brain Injury – Central Control Dysfunction – Motor Unit Insufficiency – Peripheral Sensory and Motor Impairment – Structural Impairment Pathological Gait • Brain injury can interfere with gait in several ways causing: – Primary effects – Secondary effects – Tertiary effects Pathological gait is a mixture of primary, secondary and tertiary abnormalities. Gage JR, Schwartz M 4 5/7/2014 Pathological Gait Pathological Gait • Secondary Effect • Primary Effect – Occurs as a direct result of a brain injury – Examples in periventricular leukomalacia (PVL) might be: • Loss of selective muscle control • Balance difficulties • Abnormal muscle tone Gage JR, Schwartz M – Because the primary effects of brain injury impose abnormal forces on the skeleton, neither bone nor muscle grow normally. – These changes are not immediate. – Muscles and bones grow slowly over time, and these skeletal deformities emerge slowly and in direct proportion to the rate of skeletal growth. Gage JR, Schwartz M Pathological Gait Pathological Gait • Central Control Dysfunction • Tertiary Effects – The primary and secondary effects of the brain injury burden the patient/child with structural and dynamic abnormalities that make walking difficult. – The patient/child will develop “coping or compensatory mechanisms” to walk which increases energy consumption. – These coping mechanisms represent the tertiary effects of brain injury. – Upper motor neuron pathways control the anterior horn cells, determining which muscles are activated. • Brain lesions such as stroke, acquired brain injury or cerebral palsy are common causes. • Cervical and thoracic spinal cord injuries are others. • Spasticity is a universal characteristic. • Patients differ considerably due to variability in loss of selective control and emergence of primitive control mechanisms. Gage JR, Schwartz M Gage JR, Schwartz M Pathological Gait Pathological Gait • Motor Unit Insufficiency • Motor Unit Insufficiency – Muscle weakness is the clinical penalty of having fewer motor units available to generate the forces needed for walking. Perry 1967 – Muscle weakness • Lower Motor Neuron Disorders – Poliomyelitis, GuillainBarré Syndrome • Muscular Pathology – Muscular Dystrophy • Patients can substitute for local weakness since sensation and central control have been maintained. Perry 1967 5 5/7/2014 Pathological Gait Pathological Gait • Peripheral Sensory and Motor Impairment: – Examples: • Peripheral Sensory and Motor Impairment – The addition of a sensory loss to muscle paralysis reduces the patient’s ability to Perry substitute. Pathological Gait • Structural Impairment – Although some lesions can cause hypermobility, restricted passive motion and malalignment are more common problems – Contributing pathologies are: • Contractures • Skeletal Deformity • Cauda Equina Spinal Cord Injury • Spina Bifida • Acute Trauma – Impaired Sensation delays awareness of floor contact. – Walking ability decreases with each higher level of spinal cord impairment. Perry 1967 Pathological Gait • Structural Impairment – Contracture: Freedom to move is impaired by fibrous connective tissue stiffness • Plantarflexion • Knee Flexion • Hip Flexion – Congenital – Traumatic • Musculoskeletal Pain Perry 1967 Pathological Gait Perry 1967 Pathological Gait • Structural Impairment • Structural Impairment – Contracture: Plantarflexion • A 15° contracture can significantly impair stance limb progression. – Contracture: Knee Flexion • Threatens stance stability • A 15° knee flexion contracture requires 20% of max quad effort • At 30°, a force equal to 50% of max is required. Perry 1967 Perry 1967 6 5/7/2014 Pathological Gait Pathological Gait • Structural Impairment – Contracture: Hip Flexion • Threatens stance stability and forward progression • Structural Impairment: Skeletal Malalignment – Can lead to motion errors or abnormal movement during gait – Deformed joint surfaces or supporting shafts can be further impaired by continued weight bearing. • Wolf Law, 1882: Weight bearing pattern alters bony architecture. – Children – susceptible to developing deformed and asymmetric skeletal structures – Adults – lack growing tissue; therefore, develop degenerative changes that lead to pain and loss of function Perry 1967 Pathological Gait • Structural Impairment – Musculoskeletal Pain • Protective response leads to shortened stance limb period • Trauma or inflammation can result in swelling which reduces ROM and causes patient to assume position of least discomfort Pathologic Gait Assessment • Clinical Assessment (Clues) – ROM – MMT • Observational Gait Analysis – Primary Patterning (weight bearing) – Secondary Patterning (swing phase) – Compensatory patterning • Patient’s Profile Perry 1967 Pathological Gait Assessment • ROM: R1, R2 Values • Help to define the functional and passive profile of the patient. • Help to define a difference between a stiff or spastic muscle • Give clues as to what to look for in the observational gait analysis • Start to define the angular parameters of the initial orthotic design. Pathological Gait Assessment • MMT • Helps to define the patient’s physical profile • Gives clues as to what to look for in the observational gait analysis • Starts to help define the necessary mechanical forces that the orthotic design should re-establish 7 5/7/2014 Observational Gait Analysis • Foot and Ankle Observational Gait Analysis • Knee – Attitude of foot at end of swing – Part of foot contacting ground at initial contact – Foot progression angle in stance & swing in reference to line of progression & plane of the knee (ext rot 5o) – Is the foot plantargrade in stance? – Does foot go through normal rockers? – Attitude of the knee at terminal swing (nearly full extension) – Does knee fully extend or hyperextend at any point? – To what degree does knee flex during swing (normal swing phase knee motion – 60o)? – What is knee progression angle in swing and stance? Perry 1967 Perry 1967 Observational Gait Analysis • Trunk, Pelvis and Hip – Adduction deformity at hip in swing – Persistent flexion of the hip – Sagittal plane hip motion (normal ~ 45o) – Is pelvic motion excessive in sagittal, coronal or transverse plane? – Position of the upper trunk with reference to the base of support Pathological Gait Assessment • Patient’s Profile – Goals – Expectations – Needs • Orthotic Design – – – – Correct or Accommodate Assist/Resist Motion Stability/Balance Function Perry 1967 Overview • ~3% of US population use some type of an orthosis. • Majority are prescribed by PM&R and Orthopedics. GOALS OF ORTHOTIC TREATMENT 8 5/7/2014 Overview • A broad range of individuals with varied diagnoses, impairments, and activity limitations may benefit from the use of an orthosis – – – – – Muscle weakness Spasticity Uncoordinated muscle movement Skeletal deformity or weakness Trauma or congenital defect Overview Overview A good Orthotic Evaluation should include assessment of: • Diagnosis • Treating diagnosis • Impact of other diagnoses • • • • Strength Range of Motion Skeletal Alignment Observational Gait Analysis A good Orthotic Prescription should include: • Motor Control • Coordination • Posture • Sensation • Balance • Primary: weight bearing patterns • Secondary: swing phase patterns • Compensatory patterns Goals of Orthotic Treatment • Prevent deformity • Orthosis design must: – Control the bony segments of the lower extremity – Meet musculotendinous objectives – Meet motor control objectives – Meet functional objectives Prevention of Deformity • Provide optimal skeletal alignment – Understand normal alignment – Appreciate what is attainable for that patient – Consider its impact on orthotic design and on the patient’s function – Provide optimal skeletal alignment • Provide stability – Block aberrant motion – Assist or resist joint motion • Facilitate function – Harness GRFs to optimize movement thru swing and stance Facilitation of Function • Harness ground reaction forces – Appreciate how GRF affects the limb during stance – Understand how external moments generated affect each joint 9 5/7/2014 Design Criteria Necessary to Achieve These Goals • Accurate impression - optimizing alignment • Application of appropriate three point force systems • Application of appropriate materials and componentry • Height appropriate to control joints as indicated • Total contact fit/pressure distribution Application of Appropriate Three Point Force Systems • Perform static and dynamic analysis • Separate swing and stance phase problems • Attempt to identify segment deviations. • Organize force systems Define Trimlines • These must be appropriate to accommodate force systems defined above 10 5/7/2014 Height Appropriate to Control Joints as Indicated • Relate to Perry’s three rocker concept. • Consider orthoses’ affect on GRFs and their impact on the external moments created on the more proximal joints. • Define height. Fitting and Tuning Orthosis The shank to vertical angle (SVA) is different from the angle of the ankle (AA) • Assess the shank to vertical angle – Assess angle of ankle in the orthosis – Heel sole differential • Assess additional footwear characteristics such as stiffness and profile of heel and sole AA – Heel Rocker – Toe Rocker – Flexibility of the toe of the orthosis SVA Owen 2004 11 5/7/2014 Writing the Lower Limb Orthotic Prescription Purposes of the Prescription • Communication • Billing • Legal/regulatory issues Who Best Knows the Patient Time of Initial Orthotist’s Examination? Why Written Communication? • Constraints of therapists & orthotists – Time – Geography – Rarely have PT/CO/MD/patient in same room at same time • Clarity – Reduce risk of miscommunication – Provide contact information Who Best Knows the Patient at Time of Initial Orthotist’s Examination? • Communication critical if patient has fluctuations in: Communication with Patient • Informed consent process • Orthotic trial ideal – Impairments: • • • • Tone Edema Muscle &/or general fatigue Behavior – Level of function/activity • Assist level • Endurance – Opens door for communication • • • • • Goals/expectations What orthosis can/cannot do Cosmesis Weight Issues related to clothing, toileting, etc 12 5/7/2014 Essential Parts of Prescription • • • • Patient information Contact information of referring providers Contact information of recommended orthotist All diagnoses – Include precautions • Orthosis &/or shoe modifications – Side – Type – Components & features suggestions/requests Medical Necessity • Why is orthosis needed? • What issues are you trying to control/support or assist during: – Gait – Standing – Transfers – Bed or wheelchair positioning Case Examples Good, Bad, or Ugly? AFO? Good, Bad, or Ugly? 13 5/7/2014 Thank you! Questions? 14 ABC NEURO CLINIC 1333 SMITH ST HOUSTON, TX 77030 EQUIPMENT PRESCRIPTION LETTER OF MEDICAL NECESSITY DATE: 5/7/14 PATIENT NAME: Bubba Jones DIAGNOSIS: Paralysis ITEMS AND SPECIFICATIONS: • Orthotic MEDICAL NECESSITY: PHYSICIAN’S SIGNATURE:_____________________________ DATE:_________________ PHYSICIAN’S NAME: (unreadable signature of Dr. Knowitall) 713-797-xxxx (phone number no longer working) ALMOST GOOD NEURO CLINIC 1333 SMITH ST HOUSTON, TX 77030 EQUIPMENT PRESCRIPTION LETTER OF MEDICAL NECESSITY DATE: 5/7/14 PATIENT NAME: Donnita Brace DIAGNOSIS: Post-polio syndrome; progressive neuromuscular atrophy PHYSICAL THERAPIST: Carolyn Da Silva, PT, DSc, NCS (713-794-2087) VENDOR: LENGTH OF NEED: 99 months ITEMS AND SPECIFICATIONS: L AFO MEDICAL NECESSITY: Walking difficulty, high fall risk PHYSICIAN’S SIGNATURE:_____________________________ DATE:_________________ PHYSICIAN’S NAME: Dr. E. Strangelove 1333 Smith St Houston, TX 77030 713-797-xxxx fax 713-797-xxxx STRIVING FOR EXCELLENCE NEURO CLINIC 1333 SMITH ST HOUSTON, TX 77030 EQUIPMENT PRESCRIPTION LETTER OF MEDICAL NECESSITY DATE: 5/9/14 PATIENT NAME: Anita Brace DIAGNOSIS: Post-polio syndrome; progressive neuromuscular atrophy; leg length discrepancy; s/p partial arthrodesis L ankle; degenerative joint changes L ankle; L sacroiliac pain PHYSICAL THERAPIST: Carolyn Da Silva, PT, DSc, NCS (713-794-2087) VENDOR: Hanger Orthotics, Jason Jennings, CPO 713-747-4171 LENGTH OF NEED: 99 months ITEMS AND SPECIFICATIONS: L AFO • As lightweight as possible, evaluate for plastic design • Rear entry/ground reaction design • Articulating ankle o Dorsiflexion stop prior to onset of pain in stance o Dorsiflexion assist Shoe modifications • Heel lift on L • Rocker soles on B shoes MEDICAL NECESSITY: Mrs. Brace is a 58 year old female with history of polio and post-polio syndrome. She has B lower extremity weakness, with the L side being weaker than the R. She has been walking fulltime without assistive devices or orthosis since healing from her childhood arthrodesis (joint fusion). Currently, she has severe pain in the anterior part of her ankle during stance phase, as she progresses through midstance into terminal stance and preswing subphases. Her pain intensifies as she walks longer distances. As she becomes more painful, she compensates in ways to try to minimize the pain, causing excessive wear and tear on other joints, including her L sacroiliac joint. She requires an AFO that is lightweight to avoid over-fatiguing her already weak muscles. It needs to rigidly block her painful dorsiflexion in stance phase as described above. However, it also needs a jointed ankle to allow the plantarflexion that should occur from initial contact into loading response to allow as smooth weight acceptance into stance as possible for joint protection, pain management, and energy efficiency. Mrs. Brace also requires shoe modifications to minimize (not necessarily correct) her structural leg length discrepancy. The heel lift will also reduce the amount of dorsiflexion required during stance phase, thereby helping to reduce her pain. The rocker bottom soles are required to allow a more efficient transition from terminal stance into preswing, since the rigidity of the AFO will hinder her mechanical 3rd/toe rocker. PHYSICIAN’S SIGNATURE:_____________________________ DATE:_________________ PHYSICIAN’S NAME: Dr. Wonderful 1333 Smith St Houston, TX 77030 713-797-xxxx fax 713-797-xxxx References Adams R, Gandevia S, Skuse N. The distribution of muscle weakness in upper motorneuron lesions affecting the lower limb. 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