Understanding the Transtibial and Transfemoral Limb/Socket Interfaces

Presented by John Fergason

Why is the interaction between the residual limb and the socket so critical? Many fitting problems can be solved if a full understanding of the socket biomechanics is gained. This course relates the forces that occur on the limb in each phase of gait, allowing the clinician to isolate issues that may hinder progress in therapy. It also explores why the training of the patient with a transfemoral amputation is so much more complicated. The transfemoral patient has no direct muscle control of the knee function. Knee stability and control are of paramount importance to maintain safety and stability during ambulation. This course will correlate the forces that occur both on the limb and the knee to each phase of gait. Problem solving can be augmented by noting the knee stability at each phase of gait and how the skin appears after ambulation.

Meet your instructor

A person wearing glasses and a blue shirt smiles against a wavy white backdrop.

John Fergason

John Fergason is the chief prosthetist at the Center for the Intrepid at San Antonio Military Medical Center. He was formerly an instructor and clinical manager for the Prosthetics-Orthotics Program at UT Southwestern in Dallas, Texas, and proceeded to become the director of the Division of Prosthetics-Orthotics at the…

Read full bio

Chapters & learning objectives

1. Socket Shape and Transtibial Residual Limb Weight Bearing Regions

Socket design is directly related to the regions of weight bearing ability on the residual limb. This chapter will emphasize relation between the socket and residual limb in both the static and dynamic environment.

2. Terminology and Gait Biomechanics of the Transtibial Prosthesis

Biomechanics of transtibial gait is the foundation for successful early ambulation training with a transtibial prosthesis. Emphasis will be placed on the terminology most applicable to apply a framework of understanding of the forces placed on the residual limb during ambulation.

3. How the Ground Reaction Force Affects the Transtibial Residual Limb During Gait

This chapter now builds on the previous knowledge of weight bearing regions of the limb and the biomechanical forces that act upon it during each phase of gait. Each phase of gait will be discussed in the context of the tibial position within the socket and how this affects the ability to ambulate efficiently.

4. Socket Shape and Transfemoral Residual Limb Weight Bearing Regions

Transfemoral socket design continues to evolve as various theories are introduced and incorporated into the field of study. General weight tolerant areas of the residual limb will be discussed and related to several common socket design approaches. This chapter emphasizes the dynamic nature of the femur position in both the coronal and sagittal planes during static standing and dynamic ambulation.

5. Terminology and Gait Biomechanics of the Transfemoral Prosthesis

Biomechanics of transfemoral gait provides an understanding of how to train the patient to maintain knee stability during both level ground walking and when encountering environmental barriers. A review of terminology will provide a reference for a study of the importance of knee control in the context of each phase of gait.

6. How the Ground Reaction Force Affects Knee Stability and the Transfemoral Residual Limb During Gait

Each phase of gait will be discussed in the context of the trochanter-knee-ankle (TKA) line, and the ground reaction force vector effect on the joint moments that affect knee stability.

More courses in this series

Understanding Lower Extremity Limb Loss

Alicia White

Evaluating Patients with Amputations

Alicia White

Rehabilitation after Lower Extremity Limb Loss

Alicia White

Prosthetic Training After Lower Extremity Limb Loss

Alicia White

Pre-Prosthetic Management of Lower Limb Amputation

John Fergason