Biomechanics of Quadrilateral socket

For Transfemoral prosthesis Quadrilateral socket is a common socket design . This presentation is about the biomechanics of the Quadrilateral socket .

1. BANGLADESH HEALTH PROFESSIONS INSTITUTE BHPI-CRP School of Prosthetics and Orthotics Biomechanics of Quadrilateral Socket Shishir Chandra Bin Intern PO (01)

2. Content Objective Introduction Quadrilateral socket Quadrilateral socket shape Quadrilateral socket wall Biomechanical principles of Quadrilateral socket Summary

3. Objective To know about Quadrilateral socket To know about the socket wall To know about Quadrilateral socket biomechanics

4. Introduction Clinicians have 2 types of prosthetic sockets for patients with a transfemoral amputation : Quadrilateral socket introduced in the 1950s Ischial containment socket introduced in the 1980s For many years , the quadrilateral socket was acceptable to clinicians and patients alike . But QL socket has some disadvantage , and that’s why Nowadays IRC socket has become more popular .

5. Quadrilateral socket Quadrilateral socket refers to socket shape viewed in transverse plane . Quad = four Four walls are Medial Anterior Lateral Posterior

6. Quadrilateral socket shape

7. Quadrilateral socket wall Quadrilateral socket has four walls . Four walls are Medial wall Anterior wall Lateral wall Posterior wall

8. Quadrilateral socket biomechanics Quadrilateral socket biomechanics : Total contact Firmness and softness of tissue The effect of sloped surfaces on stump/socket pressures High anterior wall Stabilization of the femur and pelvis Initial flexion of the socket

9. Quadrilateral socket biomechanics Total contact : Good blood circulation(prevent oedema ) Increased surface area(reduced pressure) Improved proprioception(easy to control prosthesis)

10. Quadrilateral socket biomechanics Firmness and softness of tissue: Contracted large muscles are related to firm tissue (need relief ) Femoral triangle and lateral surface is soft tissue area(increase pressure over these areas)

11. Quadrilateral socket biomechanics The effect of sloped surface on stump: The best supporting surface to take weight is a horizontal surface The TF stump does not tolerate end bearing Weight is distributed proximally at the Ischial Tuberosity area

12. Quadrilateral socket biomechanics High anterior wall: Ischial tuberosity tends to slide forward ( For this posterior counter force needed ) Pelvis also rotates anteriorly That’s why anterior wall is made 5 cm higher than posterior wall

13. Quadrilateral socket biomechanics Stabilization of the femur and pelvis: Pressure applied laterally during casting and rectification( to resist abduction of femur ) This adduction of femur stabilise the pelvis to drop on the afected side This reduces lateral trunk bending

14. Quadrilateral socket biomechanics Initial flexion of the socket : Gluteus maximus and hamstrings more effect in generating hip extension forces Helps to maintain the ischial tuberosity on its seat It improves the gait of the amputee to reduce lumber lordosis at heel off.

15. Summary Quadrilateral socket has 6 biomechanical principles . Among them 1 st three are main principles to make a proper TF socket . Quadrilateral socket walls have functions to work the socket properly . If any wall does not work properly then there will be problem with the function of the prosthesis .