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UPMSP Artificial Limb & Organ Tech study materials
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UPMSP Artificial Limb & Organ Tech practice questions

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Question 1Anatomy and Physiology of the Musculoskeletal System

Which type of bone tissue forms the dense outer shell of a long bone such as the femur?

  1. Fibrocartilage
  2. Cortical bone Correct answer.
  3. Cancellous bone
  4. Hyaline cartilage

Explanation

Cortical (compact) bone is the dense, solid tissue that forms the outer shell of long bones and resists bending and torsion. Cancellous bone is the porous, trabecular tissue found inside the metaphyses and epiphyses.

Question 2Anatomy and Physiology of the Musculoskeletal System

A prosthetic socket transmits load through the residual limb. Which structure of a long bone is the primary load-bearing diaphyseal region that must tolerate this pressure?

  1. The cortical diaphysis Correct answer.
  2. The medullary cavity
  3. The periosteum
  4. The epiphyseal plate

Explanation

The diaphysis is the tubular shaft, and its thick cortical wall is the region that bears axial and bending loads in a residual limb. The medullary cavity inside it is hollow and does not itself carry the compressive load.

Question 3Anatomy and Physiology of the Musculoskeletal System

Which muscle group of the thigh is the principal extensor of the knee and is critical for stance-phase stability in a transfemoral prosthesis user?

  1. Quadriceps femoris Correct answer.
  2. Adductor group
  3. Hip flexors
  4. Hamstrings

Explanation

The quadriceps femoris, acting through the patellar tendon, is the main extensor of the knee and controls knee stability during stance. Loss of quadriceps control is a major reason a knee unit may buckle.

Question 4Anatomy and Physiology of the Musculoskeletal System

In a person with a transtibial amputation, which muscle action is most important for controlling the residual limb within the socket during swing?

  1. Extensor hallucis longus contraction
  2. Soleus contraction
  3. Residual tibialis anterior and dorsiflexor activity Correct answer.
  4. Gastrocnemius contraction

Explanation

The dorsiflexor muscles, chiefly tibialis anterior, help position the residual limb and resist unwanted motion in the socket during swing. The plantarflexors are largely lost or altered after transtibial amputation.

Question 5Anatomy and Physiology of the Musculoskeletal System

Which joint structure distributes load and reduces friction between the femoral condyles and tibial plateau?

  1. The patellar retinaculum
  2. The menisci Correct answer.
  3. The joint capsule
  4. The cruciate ligaments

Explanation

The menisci are fibrocartilaginous wedges that increase contact area and distribute load across the knee, lowering contact stress. Ligaments and capsule provide restraint rather than load distribution.

Question 6Anatomy and Physiology of the Musculoskeletal System

Which type of muscle contraction occurs when the quadriceps lengthens while controlling knee flexion during descent onto a prosthetic limb?

  1. Isokinetic contraction
  2. Eccentric contraction Correct answer.
  3. Isometric contraction
  4. Concentric contraction

Explanation

An eccentric contraction produces tension while the muscle lengthens, which is exactly what the quadriceps do as the knee flexes under load. Concentric work shortens the muscle and isometric work holds length constant.

Question 7Anatomy and Physiology of the Musculoskeletal System

Which structure connects muscle to bone and transmits the forces needed to move a prosthetic joint?

  1. Aponeurosis
  2. Ligament
  3. Fascia
  4. Tendon Correct answer.

Explanation

A tendon is dense regular connective tissue that attaches muscle to bone and transmits contractile force. Ligaments attach bone to bone and primarily provide stability.

Question 8Anatomy and Physiology of the Musculoskeletal System

A transfemoral prosthesis user leans the trunk forward to rise from a chair. Which hip muscle group is the primary mover for this extension?

  1. Hip flexors
  2. Hip adductors
  3. Gluteus maximus and hamstrings Correct answer.
  4. Tensor fasciae latae

Explanation

Hip extension is produced mainly by gluteus maximus and the hamstrings, which raise the trunk over the femur during sit-to-stand. Trunk lean is a compensation that shifts the center of mass when hip extensor strength is limited.

Question 9Anatomy and Physiology of the Musculoskeletal System

Which type of joint is the shoulder, allowing the wide range of motion needed to position a body-powered prosthesis?

  1. Ball-and-socket joint Correct answer.
  2. Saddle joint
  3. Hinge joint
  4. Pivot joint

Explanation

The glenohumeral joint is a ball-and-socket (spheroidal) joint with three degrees of freedom, permitting flexion, abduction and rotation. That mobility is why shoulder movement can drive a cable-operated terminal device.

Question 10Anatomy and Physiology of the Musculoskeletal System

Which bony landmark of the pelvis is used to locate the ischial tuberosity, an important weight-bearing area in a transfemoral socket?

  1. Posterior superior iliac spine
  2. Anterior superior iliac spine
  3. Ischial tuberosity itself, palpated in the gluteal fold Correct answer.
  4. Greater trochanter

Explanation

The ischial tuberosity is the bony prominence palpated deep in the gluteal fold and is a key load-bearing point in ischial-ramal containment socket designs. The iliac spines and trochanter serve other landmarking purposes.

Question 11Anatomy and Physiology of the Musculoskeletal System

Which structure is the primary weight-bearing column of the vertebral column that must be considered when fitting a spinal orthosis?

  1. The vertebral bodies Correct answer.
  2. The transverse processes
  3. The laminae
  4. The spinous processes

Explanation

The vertebral bodies are the stacked cylindrical elements that transmit axial load through the spine and bear most of the compressive force. The posterior elements serve as muscle attachments and protect the canal.

Question 12Anatomy and Physiology of the Musculoskeletal System

Which muscle is the chief dorsiflexor of the ankle and is often weakened after a transtibial amputation, affecting foot clearance in swing?

  1. Tibialis anterior Correct answer.
  2. Soleus
  3. Peroneus longus
  4. Gastrocnemius

Explanation

Tibialis anterior is the principal dorsiflexor, lifting the foot during swing so the toe clears the ground. In a transtibial amputation the distal attachment is lost, so the prosthetist must compensate through alignment and foot design.

Question 13Anatomy and Physiology of the Musculoskeletal System

Which type of cartilage covers the articular surfaces of bones in synovial joints?

  1. Elastic cartilage
  2. Hyaline cartilage Correct answer.
  3. Fibrocartilage
  4. Calcified cartilage

Explanation

Hyaline cartilage forms the smooth, low-friction articular surface of synovial joints and distributes load across the joint. Elastic cartilage is found in the ear and epiglottis, and fibrocartilage in discs and menisci.

Question 14Anatomy and Physiology of the Musculoskeletal System

A patient with a transfemoral amputation shows excessive lordosis and trunk lean while standing. Weakness of which muscle group best explains this compensation?

  1. Ankle plantarflexors
  2. Hip extensors Correct answer.
  3. Hip adductors
  4. Knee flexors

Explanation

Weak hip extensors allow the pelvis to tilt anteriorly, so the user leans the trunk to place body weight behind the hip and stabilize the prosthetic knee. Strengthening hip extensors and adjusting alignment reduce this compensation.

Question 15Anatomy and Physiology of the Musculoskeletal System

Which nerve innervates the deltoid, whose function is essential for shoulder control in an externally powered upper-limb prosthesis?

  1. Musculocutaneous nerve
  2. Axillary nerve Correct answer.
  3. Median nerve
  4. Radial nerve

Explanation

The axillary nerve (C5-C6) supplies the deltoid and teres minor, so its function determines shoulder abduction strength. Musculocutaneous, radial and median nerves supply other muscle groups of the arm and forearm.

Question 16Anatomy and Physiology of the Musculoskeletal System

Which plane of the body divides it into left and right halves and is used to describe abduction and adduction of a prosthetic limb?

  1. Coronal plane Correct answer.
  2. Transverse plane
  3. Sagittal plane
  4. Oblique plane

Explanation

The coronal (frontal) plane divides the body into anterior and posterior parts, and abduction and adduction occur within it. The sagittal plane divides the body into left and right and contains flexion and extension.

Question 17Anatomy and Physiology of the Musculoskeletal System

Which muscle of the forearm flexes the elbow and supinates the forearm, actions that position a hand prosthesis for grasping?

  1. Pronator teres
  2. Brachioradialis
  3. Triceps brachii
  4. Biceps brachii Correct answer.

Explanation

The biceps brachii flexes the elbow and is a strong supinator, allowing the hand to be turned palm up for grasp. The triceps extends the elbow, and pronator teres rotates the forearm the opposite way.

Question 18Anatomy and Physiology of the Musculoskeletal System

Which type of bone cell resorbs bone matrix and is relevant to residual limb remodeling after amputation?

  1. Osteoblast
  2. Osteoclast Correct answer.
  3. Chondrocyte
  4. Osteocyte

Explanation

Osteoclasts are multinucleated cells that resorb bone and work with osteoblasts to remodel the skeleton. After amputation, altered loading drives remodeling of the residual bone.

Question 19Anatomy and Physiology of the Musculoskeletal System

Which structure of the residual limb provides the soft tissue padding that must be protected when designing a prosthetic socket?

  1. The subcutaneous fat and muscle envelope Correct answer.
  2. The bone cortex
  3. The joint capsule
  4. The periosteum

Explanation

Subcutaneous fat and residual muscle form the soft tissue envelope that cushions pressure and shear at the socket interface. Socket fit must distribute load over this tissue while avoiding areas where bone lies just beneath the skin.

Question 20Anatomy and Physiology of the Musculoskeletal System

Which muscle group acts as the primary plantarflexors responsible for push-off, whose loss changes gait in a transtibial prosthesis user?

  1. Gastrocnemius and soleus Correct answer.
  2. Peroneus tertius and tibialis anterior
  3. Tibialis anterior and extensor digitorum longus
  4. Extensor hallucis longus and extensor digitorum longus

Explanation

The gastrocnemius and soleus form the triceps surae, the main plantarflexors that generate push-off at the end of stance. After transtibial amputation this power is lost and must be replaced by prosthetic foot design and alignment.

Question 21Anatomy and Physiology of the Musculoskeletal System

Which ligament prevents anterior translation of the tibia relative to the femur and stabilizes the prosthetic knee in stance?

  1. Posterior cruciate ligament
  2. Lateral collateral ligament
  3. Medial collateral ligament
  4. Anterior cruciate ligament Correct answer.

Explanation

The anterior cruciate ligament restrains anterior tibial translation and controls rotational stability of the knee. Collateral ligaments resist varus and valgus forces rather than anteroposterior shear.

Question 22Anatomy and Physiology of the Musculoskeletal System

In a myoelectric hand prosthesis, which remaining forearm muscle group is commonly used to provide the electromyographic control signal for grasp closure?

  1. Shoulder abductors
  2. Wrist extensors
  3. Wrist flexors Correct answer.
  4. Elbow extensors

Explanation

Wrist flexors are commonly used for grasp closure, while wrist extensors typically drive opening, giving a simple two-site control scheme. Signals are recorded from residual muscle activity at the electrode site.

Question 23Anatomy and Physiology of the Musculoskeletal System

Which feature of a synovial joint produces synovial fluid that lubricates the articulating surfaces?

  1. The synovial membrane Correct answer.
  2. The articular cartilage
  3. The subchondral bone
  4. The fibrous capsule

Explanation

The synovial membrane lines the joint cavity and secretes synovial fluid, which lubricates and nourishes the articular cartilage. The fibrous capsule provides mechanical restraint but does not produce the fluid.

Question 24Anatomy and Physiology of the Musculoskeletal System

A clinician notes that a transfemoral prosthesis user's knee buckles just after heel strike. Which biomechanical factor of the residual limb best explains this, given normal prosthetic alignment?

  1. Excessive ankle dorsiflexion strength
  2. Excessive hip flexor strength
  3. Increased knee flexor tone
  4. Insufficient hip extensor torque to keep the ground reaction line anterior to the knee Correct answer.

Explanation

At early stance the ground reaction force must pass anterior to the prosthetic knee to keep it extended. If hip extensor torque is insufficient, the trunk cannot be positioned to achieve this, and the knee buckles.

Question 25Materials Science and Biomaterials for Prosthetics

Which material property most directly governs the fatigue life of a below-knee prosthetic foot that flexes with every step?

  1. Density measured by displacement
  2. Endurance limit under cyclic loading Correct answer.
  3. Surface hardness on the Shore A scale
  4. Coefficient of thermal expansion

Explanation

Fatigue failure occurs when a component is repeatedly loaded below its ultimate strength, so the endurance limit and S-N behaviour under cyclic stress determine how many steps a flexing foot can survive. Density, hardness and thermal expansion do not describe resistance to repeated bending cycles in the way fatigue life requires.

Question 26Materials Science and Biomaterials for Prosthetics

A prosthetic socket is laminated from epoxy resin reinforced with carbon fibre. Which term best describes the resulting material?

  1. Thermoset homopolymer
  2. Single-crystal alloy
  3. Composite Correct answer.
  4. Intermetallic

Explanation

A composite combines two distinct phases, here a polymer matrix and carbon fibre reinforcement, so that the properties of the assembly exceed those of either constituent alone. The fibre carries load while the resin transfers stress and holds shape.

Question 27Materials Science and Biomaterials for Prosthetics

Which polymer is most widely used for the flexible inner liner of a transtibial socket because of its combination of compliance and durability?

  1. Silicone elastomer Correct answer.
  2. Polytetrafluoroethylene
  3. Polypropylene homopolymer
  4. Polymethyl methacrylate

Explanation

Silicone elastomers are chosen for liners because they are soft, skin-friendly, and retain elasticity over many loading cycles while distributing pressure. Their low modulus cushions the residual limb without the rigidity of socket-shell plastics.

Question 28Materials Science and Biomaterials for Prosthetics

In a titanium alloy used for a prosthetic pylon, what is the main reason aluminium is added?

  1. To raise magnetic permeability
  2. To stabilise the alpha phase and lower density Correct answer.
  3. To increase electrical conductivity
  4. To act as a solid lubricant

Explanation

Aluminium is an alpha stabiliser in titanium alloys; it strengthens the alpha phase and helps keep density low, which is valuable in a weight-bearing pylon. Vanadium, by contrast, stabilises the beta phase.

Question 29Materials Science and Biomaterials for Prosthetics

A clinician wants a socket that can be reheated and reshaped several times during fitting without chemical cure. Which class of polymer should be selected?

  1. Thermoplastic Correct answer.
  2. Thermosetting resin
  3. Vulcanised rubber
  4. Cross-linked hydrogel

Explanation

Thermoplastics soften on heating and harden on cooling reversibly, so a socket can be re-formed repeatedly during fitting. Thermosets and vulcanised rubbers cure into a permanent network and cannot be reshaped by reheating.

Question 30Materials Science and Biomaterials for Prosthetics

Why is a controlled post-cure heating step applied to a laminated prosthetic socket?

  1. To lower the glass transition temperature of the resin
  2. To complete resin cross-linking and reduce residual stress Correct answer.
  3. To introduce porosity for ventilation
  4. To melt the reinforcing fibres for better bonding

Explanation

Post-curing drives the epoxy reaction closer to completion and lets residual stresses from lamination relax, which improves dimensional stability and strength. It does not melt the reinforcement or deliberately create porosity.

Question 31Materials Science and Biomaterials for Prosthetics

A prosthetic foot design must return energy during push-off. Which material characteristic is most relevant?

  1. Low melting point for easy moulding
  2. High ductility with large plastic deformation
  3. High surface friction coefficient
  4. High elastic strain energy storage with low hysteresis Correct answer.

Explanation

Energy-returning feet store elastic strain energy as they deflect and release it at push-off, so the material needs high elastic energy storage and low hysteresis to avoid losing that energy as heat. Plastic deformation would waste the stored energy permanently.

Question 32Materials Science and Biomaterials for Prosthetics

Which material is commonly used for the rigid outer shell of a definitive transtibial socket because of its high stiffness-to-weight ratio?

  1. Silicone gel sheet
  2. Natural rubber
  3. Carbon-fibre reinforced epoxy Correct answer.
  4. Polyurethane foam

Explanation

Carbon-fibre reinforced epoxy gives a stiff, light shell that can carry body weight and bending loads with thin walls. Foams, gels and rubbers are too compliant to act as the structural shell.

Question 33Materials Science and Biomaterials for Prosthetics

A residual limb interface material is required to wick moisture and reduce skin maceration inside a liner. Which approach is most appropriate?

  1. A knitted textile with hydrophilic fibres in contact with skin Correct answer.
  2. A continuous non-porous silicone sheet
  3. A closed-cell polyethylene foam pad
  4. A solid polycarbonate plate

Explanation

Moisture management requires transport of sweat away from the skin, which a hydrophilic knitted textile achieves by capillary wicking. Non-porous sheets, closed-cell foams and rigid plates trap moisture against the skin.

Question 34Materials Science and Biomaterials for Prosthetics

Which test method is most appropriate for measuring the tensile strength of a cured silicone liner material?

  1. Charpy impact test on a notched bar
  2. Four-point flexural test on a rigid beam
  3. Rockwell hardness test on a flat disc
  4. Tensile test on a dumbbell specimen per a standard elastomer method Correct answer.

Explanation

Tensile strength of an elastomer is measured by pulling a dumbbell-shaped specimen to failure in a tensile testing machine, following an elastomer-specific standard. Impact, hardness and flexural tests measure other properties.

Question 35Materials Science and Biomaterials for Prosthetics

Why is 316L stainless steel sometimes preferred over a higher-strength alloy for temporary prosthetic components?

  1. It is fully bioresorbable
  2. It has the highest fatigue limit of all implant metals
  3. It is lighter than titanium
  4. It offers good corrosion resistance and adequate strength at low cost Correct answer.

Explanation

316L stainless steel provides reliable corrosion resistance and sufficient strength for temporary or low-load components at modest cost. It is not the highest-fatigue-strength option, is denser than titanium, and is not resorbable.

Question 36Materials Science and Biomaterials for Prosthetics

A prosthetic component will be repeatedly steam-sterilised in a clinic autoclave. Which material behaviour must be checked first?

  1. Hydrolytic and thermal stability at sterilisation temperature Correct answer.
  2. Colour fastness to sunlight
  3. Magnetic susceptibility
  4. Optical clarity

Explanation

Autoclaving exposes the material to high-temperature saturated steam, so resistance to hydrolysis and thermal degradation determines whether the component survives repeated cycles. Magnetic, optical and colour properties do not govern sterilisation durability.

Question 37Materials Science and Biomaterials for Prosthetics

Which mechanism best explains why a hydrogel liner reduces friction against the residual limb?

  1. It chemically bonds to the skin surface
  2. It melts at body temperature
  3. It generates a static electric charge
  4. A water-rich boundary layer provides fluid-film lubrication Correct answer.

Explanation

Hydrogels hold a large water fraction that forms a lubricious boundary layer, lowering the coefficient of friction against skin. They do not chemically bond to skin, rely on electrostatic effects, or melt at body temperature.

Question 38Materials Science and Biomaterials for Prosthetics

Which material pair is most suitable for a prosthetic knee joint bearing surface requiring low friction and wear resistance?

  1. Cobalt-chromium alloy against ultra-high-molecular-weight polyethylene Correct answer.
  2. Polypropylene against polyurethane foam
  3. Aluminium against magnesium
  4. Silicone against natural rubber

Explanation

The metal-on-polyethylene pairing of cobalt-chromium against UHMWPE is a well-established low-friction, wear-resistant bearing combination. Soft-on-soft or reactive metal pairs wear rapidly and generate debris.

Question 39Materials Science and Biomaterials for Prosthetics

A socket laminate delaminates after several months of use. Which factor is the most likely materials-related cause?

  1. Use of a release agent on the mould surface
  2. Incomplete resin wet-out leaving voids between fibre layers Correct answer.
  3. Excessive fibre volume fraction throughout the laminate
  4. Over-curing beyond the resin's glass transition

Explanation

Delamination usually originates at weak interlayer bonds and voids, which occur when the resin fails to wet out the fibres fully during lay-up. Good wet-out and controlled void content are essential for interlaminar strength.

Question 40Materials Science and Biomaterials for Prosthetics

Why is a thin layer of parylene sometimes applied to a metallic prosthetic implant surface?

  1. It acts as a structural load-bearing coating
  2. It increases the implant's magnetic strength
  3. It provides a conformal, pinhole-free barrier against body fluids Correct answer.
  4. It dissolves slowly to release drugs

Explanation

Parylene is deposited as a thin conformal polymer film that protects metal surfaces from corrosive body fluids while adding negligible thickness. It is not structural, magnetic, or primarily a drug-release matrix.

Question 41Materials Science and Biomaterials for Prosthetics

Which property of ultra-high-molecular-weight polyethylene makes it suitable for prosthetic socket flexible inner components?

  1. High thermal conductivity
  2. High magnetic permeability
  3. High abrasion resistance with good toughness Correct answer.
  4. High electrical conductivity

Explanation

UHMWPE combines excellent abrasion resistance with toughness, which suits flexible inner socket elements that see repeated rubbing. Its electrical, magnetic and thermal transport properties are not the reason for selection.

Question 42Materials Science and Biomaterials for Prosthetics

A prosthetic foot is being designed for a heavy user. Which combination of material properties should be prioritised?

  1. High strength and high fatigue resistance with moderate stiffness Correct answer.
  2. Low toughness and high hardness
  3. Low strength and high ductility
  4. High density and low stiffness

Explanation

Heavy users impose large cyclic loads, so the foot needs high strength, high fatigue resistance and stiffness tuned to store and return energy without excessive deflection. Low strength, low toughness or excessive density would compromise durability or weight.

Question 43Materials Science and Biomaterials for Prosthetics

What is the primary reason glass fibre rather than carbon fibre is chosen for some prosthetic laminates?

  1. Lower cost with adequate strength for lower-load components Correct answer.
  2. Higher fatigue strength than carbon at equal volume fraction
  3. Higher stiffness-to-weight ratio than carbon
  4. Better electrical conductivity

Explanation

Glass fibre costs much less than carbon while providing adequate strength and stiffness for lower-load components. Carbon offers a higher stiffness-to-weight ratio and generally better fatigue performance at equal fibre volume fraction.

Question 44Materials Science and Biomaterials for Prosthetics

Which statement about the viscoelastic behaviour of a prosthetic liner material is correct?

  1. Its stress response depends on the rate of applied strain Correct answer.
  2. Its stiffness is independent of loading rate
  3. It behaves as a perfectly elastic solid at all strain rates
  4. It shows no creep under sustained load

Explanation

Viscoelastic materials exhibit time- and rate-dependent behaviour, so the stress developed for a given strain depends on how fast that strain is applied. They also creep and relax, which contradicts rate-independent or perfectly elastic descriptions.

Question 45Prosthetic Measurement, Casting, and Fitting Techniques

During transtibial casting, which hand position best maintains the patellar tendon bar while the plaster sets?

  1. Both palms compress the tibial crest medially and laterally at mid-shaft
  2. The thumb of one hand presses posteriorly just below the patella while the fingers wrap the popliteal area Correct answer.
  3. The thenar eminence presses the distal tibia anteriorly while the fingers pull the calcaneus forward
  4. The index finger presses the fibular head anteriorly while the thumb lifts the heel

Explanation

The patellar tendon bar is formed by a localized posteriorly directed force applied just below the patella, with the opposite hand countering at the popliteal region to control the counterforce. This creates the prominent indentation that unloads the patellar tendon during weight bearing. Pressure anywhere along the tibial crest or fibular head would create painful focal loading rather than a functional relief area.

Question 46Prosthetic Measurement, Casting, and Fitting Techniques

Which measurement is taken to determine the mediolateral dimension of a transtibial socket during initial assessment?

  1. The length from the patellar tendon bar to the distal tibial end
  2. The circumference of the limb at the patellar tendon level
  3. The width across the residual limb at the level of the tibial flares Correct answer.
  4. The distance between the medial and lateral femoral condyles

Explanation

The mediolateral dimension of a transtibial socket is derived from the width of the residual limb measured across the tibial flares, since this is the widest bony region that must be accommodated. Circumferences give girth but not the flat mediolateral width needed to shape the socket. Femoral condyle width relates to knee anatomy, not the transtibial socket.

Question 47Prosthetic Measurement, Casting, and Fitting Techniques

A plaster wrap cast for a transfemoral socket is being taken. Why is the cast rectified with a posterior shelf build-up rather than left as wrapped?

  1. To reduce pressure over the femoral triangle during swing phase
  2. To increase the anteroposterior diameter so the limb sits deeper in the socket
  3. To allow the socket to be donned without a suspension liner
  4. To provide an ischial seating surface and control rotation of the residual limb Correct answer.

Explanation

Rectification of a transfemoral cast builds an ischial seat and shapes the posterior shelf so the ischium bears weight and the limb is controlled against rotation. The anteroposterior diameter is generally reduced, not increased, over the femoral triangle. Rectification is about load distribution and rotational control, not about suspension method.

Question 48Prosthetic Measurement, Casting, and Fitting Techniques

Which casting technique is most appropriate for a residual limb with a mature, well-healed, non-oedematous transtibial amputation?

  1. An elastic bandage wrap applied without plaster
  2. A rigid plaster of Paris cast taken with the patient standing
  3. A hand-cast plaster wrap taken with the limb in extension
  4. A CAD scan of the limb followed by a milled positive model Correct answer.

Explanation

A mature, stable limb is well suited to digital scanning and a milled positive model, which gives reproducible rectification and easy storage of the shape. Hand-wrapped plaster remains valid but is not the only appropriate option; the scan approach is preferred when the limb volume is stable. Elastic bandaging alone does not produce a positive model for socket fabrication.

Question 49Prosthetic Measurement, Casting, and Fitting Techniques

When measuring a residual limb for a patellar tendon bearing socket, the measurement from the patellar tendon bar to the distal end of the limb is used to determine which socket dimension?

  1. The length of the socket from the patellar tendon bar to the distal end Correct answer.
  2. The circumference at the popliteal crease
  3. The mediolateral width at the tibial flares
  4. The anterior-posterior depth of the socket

Explanation

The distance from the patellar tendon bar to the distal end of the residual limb defines the functional length of the socket and positions the distal end relative to the bar. This length controls where the distal tibial relief and the socket end sit. Circumferences and widths are separate measurements used for girth and mediolateral shaping.

Question 50Prosthetic Measurement, Casting, and Fitting Techniques

A transfemoral cast is being rectified. The prosthetist builds up the posterior ischial area and reduces the anterior femoral triangle region. What is the primary purpose of this combination?

  1. To increase socket volume for a larger residual limb
  2. To prevent pistoning by tightening the socket circumference
  3. To create an ischial seat while relieving the neurovascular structures in the femoral triangle Correct answer.
  4. To shift weight bearing onto the femoral triangle

Explanation

The ischial seat provides a bony weight-bearing surface, while relief over the femoral triangle protects the femoral vessels and nerve. Together they distribute load to tolerant areas and avoid neurovascular compression. Shifting load onto the femoral triangle or simply tightening the circumference would cause discomfort and does not reflect rectification principles.