Orthotics is a high-yield topic for physiotherapy entrance exams. Questions typically focus on the indications (nerve injuries) and biomechanical principles of specific orthoses. This guide covers the most frequently asked lower and upper limb orthotics.
1. Ankle Foot Orthosis (AFO)
The AFO is the most commonly prescribed orthosis in clinical practice. It encompasses the ankle joint and the foot.
[Image of AFO types posterior leaf spring and solid ankle]Common Types & Indications
| Type of AFO | Key Feature | Primary Indication |
|---|---|---|
| Posterior Leaf Spring (PLS) | Flexible posterior upright. Stores energy during stance and releases it during swing. | Foot Drop (Dorsiflexor weakness) where medial/lateral stability is normal. |
| Solid AFO | Rigid ankle. Limits all movement (PF/DF and Inversion/Eversion). | Severe spasticity, ankle instability, or Charcot foot. |
| Hinged (Articulated) AFO | Allows free Dorsiflexion but blocks Plantarflexion. | Patients who have voluntary DF capability but need medial/lateral stability. |
| GRAFO (Ground Reaction AFO) | Has an Anterior Shell (over the shin). Uses ground reaction force to extend the knee. | Crouch Gait (Weak Quadriceps). Prevents knee buckling. |
2. Knee Ankle Foot Orthosis (KAFO)
A KAFO is indicated when an AFO cannot provide sufficient stability for the knee during stance phase. Common conditions include Polio, Spinal Cord Injury, and severe Quadriceps weakness.
Knee Joint Locks (Exam Favorites)
- Drop Lock (Ring Lock): The most common lock. A metal ring slides down over the joint by gravity to lock the knee in extension. The patient must manually pull it up to sit.
- Bail Lock (Pawl Lock): A posterior semicircular lever. The patient can unlock it by pressing the lever against the edge of a chair. Advantage: Hands-free unlocking.
- Offset Joint: The mechanical joint is placed posterior to the anatomical joint to increase stability in extension without a mechanical lock.
3. Essential Upper Limb Splints
For exams, always correlate the splint with the specific Nerve Injury.
A. Cock-up Splint
- Indication: Radial Nerve Palsy (Wrist Drop).
- Function: Maintains the wrist in 20-30° of extension. This prevents overstretching of the extensors and allows the fingers to function.
- Position: Wrist Extended, Fingers free.
B. Knuckle Bender Splint
- Indication: Ulnar Nerve Palsy (Ulnar Claw Hand).
- Function: It is a Dynamic Splint. It flexes the MCP joints (Knuckles) to correct the hyperextension deformity caused by intrinsic muscle paralysis.
- Mechanism: Rubber bands or springs provide the flexion force.
C. Aeroplane Splint
- Indication:
- Erb's Palsy (Brachial Plexus Injury C5-C6).
- Axillary Nerve Injury.
- Burns of the Axilla (to prevent adduction contracture).
- After shoulder reconstruction/dislocation.
- Function: Holds the arm in 90° Abduction and external rotation.
- Why "Aeroplane"? Because the arm is held out like an airplane wing.
Frequently Asked Questions (FAQs)
Static splints (e.g., Cock-up) have no moving parts and are used for immobilization or support. Dynamic splints (e.g., Knuckle Bender) use elastic components (rubber bands, springs) to mobilize stiff joints or substitute for weak muscles.
The Floor Reaction AFO (GRAFO). It applies an extension moment to the knee during the stance phase, preventing the knee from buckling (crouching).
It is often referred to as a French or Swiss lock. Its unique feature is the posterior bar that allows the patient to unlock the knee simply by backing up against a chair.
Exam Quiz: Orthotics & Splints (10 MCQs)
Test your knowledge. Click the correct option to see the answer and reasoning.
1. Which splint is primarily indicated for Radial Nerve Palsy?
Radial Nerve Palsy causes wrist drop. A Cock-up splint supports the wrist in extension to facilitate finger function.
2. The "Knuckle Bender" splint is used to correct:
Ulnar nerve injury leads to hyperextension of MCP joints (Claw hand). The Knuckle Bender flexes the MCP joints.
3. Which AFO is specifically designed to prevent knee buckling (Crouch Gait) in Cerebral Palsy?
The GRAFO has an anterior shell that utilizes ground reaction forces to create an extension moment at the knee.
4. The Aeroplane splint maintains the shoulder in:
It keeps the arm abducted to prevent adduction contractures, commonly used in axillary burns or Erb's palsy.
5. A "Bail Lock" on a KAFO is designed to:
The Bail lock allows the patient to sit down without using their hands to unlock the knee joints; pressure from the chair seat releases the lock.
6. Which material is most commonly used for modern custom-molded AFOs?
Thermoplastics like Polypropylene are lightweight, durable, and can be molded precisely to the patient's cast.
7. A Posterior Leaf Spring (PLS) AFO is contraindicated in:
PLS is very flexible and thin. It provides excellent dorsiflexion assist but offers poor medial-lateral stability, making it unsuitable for severe spasticity.
8. The biomechanical principle used by most orthoses to correct deformity is:
The three-point pressure system involves one primary force acting at the deformity and two counter-forces acting in the opposite direction above and below it.
9. Which orthosis would you prescribe for a Median Nerve Injury (Ape Thumb)?
Median nerve injury affects the thenar muscles, preventing opposition. An Opponens splint maintains the thumb in abduction and opposition.
10. The main disadvantage of a Solid AFO is:
Because the ankle is locked, the tibia cannot advance over the foot during the stance phase (loss of ankle rocker), often resulting in an unnatural gait pattern.
References
- Lusardi, M. M., & Jorge, M. (2013). Orthotics and Prosthetics in Rehabilitation. Saunders/Elsevier.
- Nawoczenski, D. A., & Epler, M. E. (1997). Orthotics in Functional Rehabilitation of the Lower Limb. Saunders.
- McKee, P., & Morgan, L. (1998). Orthotics in Rehabilitation: Splinting the Hand and Body. F.A. Davis.
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