Noelle C. Buell, MS, PT. John R. Fergason, CPO A prosthesis with a manual locking control is often designed soap and water and drying completely.
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4Copyright © 2008 by P rost heti cs Resear ch S tudy. All rights reserved. No part of this publication may be reproduced or transmi ed in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from Prosthetics Research Study. ISBN: 978-0-6152-6870-5 Funded through educational grants from O o Bock Healthcare LP and Prosthetics Research Study Ack nowledgments Prosthetics Research Study wishes to thank the following persons for their contributions as technical reviewers of this publica tion: Karen Sullivan-Kniestadt, PT; Bernice Kegel, RPT; Greg Schneider, CPO; Daniel Abrahamson, CPO; and Kathryn Allyn, CPO. Special acknowlegment is made to the following persons for their technical assistance in the development of this publication: Laurie B raun; John Michael, CPO; Katie Treadwell; and Ryan Blanck, CPO. Acknowlegment is made to the following persons for assistance with the la yout and design of this publication: Anna Brinkmann, Mara Herschbach, and Karen Lundquist. Conta ct Information For additional information regarding this monograph and/or to obtain additional copies of this publication, please contact Pros thetics Research Study at info@prs-research.org.
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TABLE OF CONTENTS 1. Introduction 12. Amputation Surgery 33. The Mechanics of Able-Bodied Gait 5 4. The Multidisciplinary Approach 13 5. Functional Levels 156. Overview of Prostheses 177. Skin 338. Acute Care 399. Initial Outpatient Evaluation 41 10. Preprosthetic Treatment 4511. Initial Prosthetic Gait Training 49 12. Gait Training with Di erent Knees 57 13. Advanced Gait Training 6114. Microprocessor Knees: The C-Leg ® 67 15. Gait Deviations and the Transfemoral Amputee 73 16. Amputation Related Pain 7717. Peer Visitors and Support Groups 81 References 85
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32. Amputation Surgery Amputation at the transfemoral level demonstrates the importance of muscle reconstruction and balance between residual muscle groups. A er a transfemoral amputation, very li le, if any, weight can be borne directly on the end of the residual limb. In addition, transection of the femur creates thigh muscles that are out of balance as the residual ß exor and abductor muscle groups overpower the residual extensors and adductors. The goal of surgery is to try to regain muscle balance and to properly position the femur for weight bearing and ambulation. The term for the surgical technique by which muscles are rea ached to bone following amputation is myodesis (Figure 1). There are two main methods for performing a myodesis. One is to drill holes through the bone and suture the muscle directly to the bone. In the other method, the surgeon secures the muscle over the bone and sutures to the periostium, the thick tissue covering the bone. For the transfemoral amputation, in which a more secure a achment is required, the Þ rst method is usually indicated. The primary hip abductor and ß exor muscles are a ached on the greater and lesser trochanter on the proximal femur, near the hip. Because they are above the surgical division in all transfemoral amputations, they are not a ected by the amputation. The adductor and extensor muscles are, however, a ached at the lower end of the femur and will be divided in a transfemoral amputation surgery. This results in weakness and a limited ability to adduct and extend the hip. Without the normal a achment of the adductor and extensor muscles, the leg tends to go into simultaneous ß exion and abduction. Therefore, to counterbalance ß exion and abduction forces, the surgeon must rea ach muscles to the femur or its periostium. This myodesis makes the residual limb stronger and more balanced and keeps the femur centered in the muscle mass. Unlike a knee disarticulation, a transfemoral amputation results in a residual limb that cannot bear the body™s weight directly on the transected end. Therefore, as noted earlier, one of the goals of transfemoral amputation surgery is to balance the muscles so that some weight can be borne on the sides of the thigh. The adductor muscles are secured to the residual femur to prevent the femur from dri ing outward (abducting). If the femur abducts, weight cannot be loaded as easily onto the side, and the bone end may press painfully against the socket. By surgically balancing the muscles, the leg can be positioned in slight adduction in the socket so that most of the weight-bearing force is on the sides of the leg and not on the distal end. Myodesis also may help to reduce fithe adductor roll,fl a collection of tissue that sometimes forms high on the inner thigh above the socket line (Figure 2) and which can be quite bothersome. While this roll is commonly caused by issues such as weight gain, mismatched socket geometry, or improper donning of the residual limb, some also believe that this adductor roll is caused in part by the retraction of muscles that have been transected and are no longer held in place. This tissue then spills out over the top of the socket, and before long a signi Þ cant roll of so tissue has accumulated in that area. The prosthetic socket may dig painfully into this extra tissue. Myodesis helps secure the adductor muscles and the so tissue over these muscles. This secure a achment of the adductor muscles appears to restrict the development of a large adductor roll. Myodesis does have a major drawback: Muscle tissue does not hold sutures very well. Think of the tissues of the muscles as Figure 1 Œ Myodesis Figure 2 Œ Adductor roll
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4being like a string mop that is encased in a plastic wrapper. The plastic wrapper is like the fascia, which is the tissue that covers the muscle. Suturing muscle is like sewing through the plastic bag and the strings of the mop. The fascia provides some reinforcement, but the individual strands of muscle do not hold suture well. A suture inserted at midthigh will dri downward in the muscle tissue because there is nothing to which it can be securely a ached. If the surgeon tries to suture across the strands and loop them together, blood ß ow is cut o to the end of the muscle. Tendon and skin hold sutures well; muscle does not; and the fascia at midthigh is quite thin and tears easily. So while myodesis is important, it may not always be successful at this level. Occasionally the myodesis will stretch out or even pull free in the postoperative period. Patients will usually say they fifelt something give.fl Some surgeons do not use myodesis as part of transfemoral amputation surgery, and sometimes, even with good surgical technique, the myodesis fails or the distal a achment stretches out gradually over time. In these situations, the end of the femur may be very prominent, the patient may have pain at the distal lateral aspect of the residual limb, the prosthetic socket may not Þ t well, and the patient may walk poorly. The Þ rst approach to managing these problems is to modify and realign the prosthetic socket. One modi Þ cation is to pad the inside of the socket on the lateral side at the midthigh, above the painful end of the femur. This pad helps to push the femur into adduction. By applying pressure over a broad area over the middle of the femur, it avoids increasing contact and pressure on the painful distal end of the femur. The second adjustment is to aggressively align the socket into adduction. This may even require changing the point where the socket a aches to the knee unit. This alignment change will pre-position the entire thigh, including the femur, into adduction to both improve loading on the lateral side of the femur and maximize the abductors. If the pain and femoral position cannot be managed by socket modi Þ cation or by aggressive adduction of the socket to preposition the femur in adduction, then surgical revision can be considered. Myodesis is harder to perform during a revision procedure than during the initial amputation, but it can be done. The thoughtful surgeon must understand the entire course of the amputation process, from the initial emergency department visit to the selection of the Þ nal prosthesis. Amputation is both devastating for the patient and challenging for the surgeon. The surgeon capable of achieving a successful amputation can indeed help improve healing, rehabilitation, and quality of life.
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53. The Mechanics of Able-Bodied Gait Locomotion, or gait, is the progressive motion of the human body while walking. Able-bodied, or finormal,fl gait refers to the typical motion of the healthy human body during walking. Able-bodied gait is commonly used as the reference when assessing a pathologic gait or an intervention designed to restore function. A Þ rm understanding of able-bodied gait is important before a empting to evaluate, quantify, or record pathologic gait. Several clinicians and researchers have de Þ ned locomotion in terms of basic, functional tasks. Inman and associates 3 de Þ ned the two basic requisites for bipedal walking: (1) sustained ground reaction forces (GRFs) that support the body, and (2) periodic movement of the feet to transfer support from one limb to the next in the direction of travel. Winter 4 de Þ nes the three main tasks of walking gait to be (1) support of the head, arms, and torso (HAT) against gravity; (2) maintenance of upright posture and balance; and (3) foot trajectory control to achieve adequate ground clearance and a gentle heel contact. Similarly, Perry and associates 5 at the Rancho Los Amigos Medical Center de Þ ned the three functional tasks of locomotion to be (1) rapid loading of the body™s weight onto the outstretched limb (weight acceptance), (2) progression of the body over the single support limb (single-limb support), and (3) unloading of the limb and movement of the limb through swing in preparation for the subsequent weight acceptance (swing limb advancement). All three methods of describing gait o er similar assessments of the functional tasks required for locomotion, including the need for body weight support and the transfer of support from one limb to the other. One primary objective of locomotion is the e cient movement of the body through space. The rhythmic, periodic motion of the limbs and body propels the body forward with a minimal expenditure of physiologic energy. Any change to the pa erns of able-bodied gait usually result in less optimal pa erns and a higher rate of energy consumption. Observing and documenting such changes helps the clinician assess progress, report diagnoses, or evaluate interventions. Although the functional tasks and objectives of locomotion may appear to be relatively straightforward, the analysis of gait is a complex task. To assist in this analysis, gait is commonly evaluated over a short period known as the gait cycle, which is further subdivided into functional segments known as phases. A methodical analysis of the phases of the gait cycle o en yields useful clinical information. The Gait Cycle The gait cycle is de Þ ned from the moment one extremity contacts the ground (initial contact) until the next contact by the same extremity. The gait cycle is grossly subdivided into stance and swing phases, each occupying approximately 60% and 40% of the overall cycle, respectively. Stance phase begins when an extremity touches the ground and lasts as long as that same extremity is in contact with the ground. Swing phase begins when an extremity leaves the ground and lasts until the same extremity again contacts the ground. At standard walking speeds, there is a short period of double- limb support when both limbs are in contact with the ground. This period of double-limb support occurs twice in the gait cycle, once from the perspective of the reference limb, and once from the perspective of the contralateral limb. Each period of double-limb support occupies approximately 11% of the normal gait cycle. 6 Phases of gait For more detailed analysis, the gait cycle is o en subdivided into eight phases that de Þ ne the major activities and motions that occur. Traditional evaluation of normal gait de Þ ned the eight phases to be heel strike, foot ß at, midstance, heel-o , toe-o , acceleration, midswing, and deceleration. 6 Because this terminology is insu cient to describe select pathologies such as ankle equinus, 7 an alternate nomenclature was developed by Perry 8 and is now commonly accepted. This terminology divides the gait cycle into the following phases: initial contact (Table 1), loading response (Table 2), midstance (Table 3), terminal stance (Table 4), preswing (Table 5), initial swing (Table 6), midswing (Table 7), and terminal swing (Table 8). INITIAL CONTACT Primar y Goals Knee fully extended Position limb for step Description: The moment at which the foot touches the ground. Ankle: The ankle joint is positioned at neutral (90º) at ground contact. The ground reaction force lies posterior to the ankle, creating a small plantar ß exion moment. The pretibial muscles (tibialis anterior, extensor digitorum longus, extensor hallucis longus) are contracted to support the weight of the foot and control plantar ß exion of the foot. Knee: The knee joint is positioned at neutral (0º) or slightly ß exed at ground contact. The ground reaction force lies anterior to the knee joint, creating an extension moment. The quadriceps muscles remain contracted in preparation for loading response. The hamstrings brie ß y contract to counter the knee extension moment and stabilize the knee. Hip: The femur is ß exed 25º with respect to the vertical at ground contact. The ground reaction force lies anterior to the hip joint, creating a large ß exion moment. The hip extensors contract to resist the ß exion moment. Pelvis: The pelvis is in 5º of forward rotation at ground contact. Table 1 Œ Detailed description of able-bodied initial contact
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