Prosthetics and Orthotics Lower Limb Technologies for Ambulation Hip Knee Ankle/Foot
Hip Joint - Anatomy
Hip Joint - Anatomy
Hip Joint ●
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Ball-and-socket joint located between the head of the femur and the acetabulum of the coxa, the synovial joint is inherently stable and ROM restricted. The joint capsule is reinforced by ligaments: –
Iliofemoral
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Transverse Acetabular
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Ischifemoral
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Pubofemoral
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ligamentum Teres
Motions include flexion, extension, abduction, adduction, rotation and circumduction. Common injuries include hip dislocation due to trauma, Limb Girdle Muscular Dystrophy (LGMD) and Hip Dysplasia.
Assistive Devices for Common Hip Disorders ●
HKAFO or Hip Brace maintains leg is desired position
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Hip Abduction Brace abduction with ambulation
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Pavlik Harness is the first stage in treatment of hip dysplasia, casting follows surgery
Knee Joint - Anatomy
Knee Joint ●
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Hinge joint between the femur and the tibia. The femur articulates with the proximal end of the tibia, the margins of the tibia are built up with meniscus to deepen the articular surface. The fibula does not see the femur but articulates with the lateral side of the tibia. Ligaments largely contribute to strength of the knee: –
Collateral Ligaments LCL and MCL give stability on joint sides
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Cruciate Ligaments ACL and PCL provide stability across the joint
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Popliteal ligaments, tendons also provide strength and stability to the joint
Knee capsule is enclosed in a tough connective tissue containing the synovial fluid, bursa, etc. Knee is modeled both as a Polycentric and Single Axis joint depending upon needs
Assistive Devices (Bracing) for Common Knee Disorders ●
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Overuse injuries include runner's knee, bursitis, tendonitis ACL and other ligament injuries result from traumatic force applied during a twisting motion Osteoarthritis can also benefit from bracing, or off-loading
Prophylactic ●
Rehabilitation
Osteoarthritic
Unicentric vs. Polycentric Knee Joint
“Lenox Hill”
Knee Orthoses
www.accessinc.com Accessible Environments, Inc.
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a) Otto Bock Basic Knee Support - 20 degrees of allowable flexion, neoprene material. Pull-on brace, fastened above and below knee. Used for OA, light instabilities and inflammation of the knee. b) Cho-Pat Dual Action Knee Strap - Strap applies pressure on the patellar tendon and tendon above the kneecap. Aims to stabilize kneecap movement and reduce quadricep forces. Full mobility is allowed. c) Otto Bock Light Knee Support - Two spiral stays M/L knee provide support along with two elastic straps for compression. Used for light instabilities, meniscus and LCL/MCL injuries. d) Otto Bock Stable Knee - Two aluminum and steel polycentric hinges provide support. Straps crossed behind the knee limit hyperextension. Two loop straps provide compression. Used for collateral and cruciate ligament injuries, meniscus tears, and hyperextension.
Lower Limb Orthoses ●
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Supplement function of an existing limb
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Primary Objectives –
Stability
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Prevent Deformity
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Facilitate Function
Users
Design Considerations –
Static or Dynamic Alignment
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Affect on MS system
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Concomitant segment deviations
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Amount of correction possible
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Individualize materials
Desired Characteristics
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LL weakness or deformity
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Spasticity
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Apply Device Easily?
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Uncoordinated muscle movement
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Do More With or W/O?
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Eliminate Pain or Discomfort
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User feels safe
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Perception of Appearance?
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Improved Quality of Life?
End result of clinical gait analysis is determination of the orthotic design.
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Other Lower Limb Orthoses : AFO ●
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Ankle Foot Orthoses protect, support and prevent or correct deformity of the foot, ankle and lower leg complex. Provide against footdrop or ankle instability associated with several conditions: stroke, spina bifida, cerebral palsy, ALS, MS, paraplegia or polio. In stance, the shin is tilted forward about 7 to 14 degrees off vertical. Ankle is not in the center of the foot. Shoes must be considered when designing the angles of AFO.
a) Solid
b) Hinged
c) Spiral
Other Lower Limb Orthoses : KAFO ●
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Knee-ankle-foot orthosis encompasses the foot, ankle, lower leg, knee and thigh. AFO + protection, correction and support of knee joint. More difficult to don/doff than AFO Typically plastics material with metal used for the knee hinges. –
Pro: more support, cosmetics, molded fit for shoewear
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Con: not as adjustable as metal
Knee locks keep the knee from bending when quadriceps are challenged. Unlocked knee hinge does not affect gait, provides knee support in the frontal plane
Other Lower Limb Orthoses : HKAFO ●
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“Full Control Braces" – located at waist to hold hips, knees, ankles, and feet. Most suited to transitional conditions or in cases where no functional control exists. Hips must both fully extend. Knee contractures place counterforce needs on the brace which cannot be tolerated by skin. So knees must be near or slightly past full extension.
AFO with Hip Strap
Full Control HKAFO
Lower Limb Prostheses ●
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Designed to replace function of a missing limb Leading cause is vascular disease, followed by trauma and congenital deficiencies. Age group 51-80 most common. Amputation Sites: –
Partial foot
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Ankle Disarticulation
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Transtibial (50% amputee population)
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Knee Disarticulation
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Transfemoral
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Hip Disarticulation
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Hemipelvectomy
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Level 0 (little or no potential for use) Level 1 (use for transfers, ambulate on level surface) Level 2 (traverse low level environmental barriers) Level 3 (variable cadence) Level 4 (exceeds basic ambulation)
Lower Limb Prostheses ●
The primary objective for a LL prosthetic device is to provide the ability for an individual to return to functional lifestyle. The prosthetic should be comfortable for extended periods and depending upon the level of sophistication may allow individual to walk or run.
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Considerations: –
Distribute forces in an even pattern
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Assist in more natural gait and external appearance
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Work with residual limb geometry and amputation site
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Lightweight components
Requirements: –
Sufficient Trunk Control and balance
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Good upper body strength
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Adequate posture
Lower Limb Prostheses ●
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Typical Components: –
Socket
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Suspension
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Pylon
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Knee Joint – C-Leg from Otto Bock
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Terminal Device
Common Problems: –
Weight Bearing
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Pain
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Residual Limb Fit
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Skin problems
Prosthetic Components
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a) BK endoskeletal prosthesis with patellar tendon bearing socket with liner, strap suspension, SACH foot b) Left to Right: SACH (single axis composite heel) foot, Seattle light foot (energy storing), Carbon Copy II (energy storing with carbon heel). c) Above knee prosthesis with ischial containment socket, TES (total elastic suspension) belt, single axis knee with extension assist, endoskeletal components, energy storing foot d) Endoskeletal AK example
