Department of Veterans Affairs

Journal of Rehabilitation Research and Development Vol. 35 No. 1, January 1998 Pages 6-13

Videofluoroscopic evaluation of prosthetic fit and residual limbs following transtibial amputation

Christian R. Bocobo, MD; Juan M. Castellote, MD, PhD; Dougal MacKinnon, MD, PhD; Ann Gabrielle-Bergman, MI) Division of Physical Medicine and Rehabilitation, Department of Functional Restoration, Staizford University Medical Center, Staizfi)rd, CA 94305; Rehabilitation Department, Facultad de Medicina, Universidad Complutense, Madrid, Spain: Department of Radiology, Stanford University Medical Center, Staizford, CA 94305

Abstract-The clinical examination of residual limb compli- cations is usually subjective and may lead to inappropriate, expensive adjustments or replacement of the prosthesis. Plain films and xeroradiography only provide static images of the residual limb and socket. The purpose of this pilot study was to develop a videofluoroscopic technique to evaluate dynamic residual limb-socket relationships during gait. Sixteen videofluoroscopic studies were performed in subjects with transtibial amputation. Anteroposterior (A-P) and lateral views were obtained. The wide view field was better than the coned view. The optimal settings were found to be in the 80 to 110 kV range during manual setting (mean values: 86.3 kV in A-P view, and 88.9 kV in lateral view). The following information was obtained: A-P residual limb motion, piston action, rolling of soft tissues, and dynamic relationships of various pressure-sensitive and pressure-tolerant parts of the residual limb with the inner socket. We consider videofluoro- scopy to be a potentially valuable diagnostic procedure for evaluating difficult prosthetic fitting problems and residual limb complications, and providing a better understanding of the residual limb-socket interface during different phases of the gait cycle.

Key words: prosthetics, residual limb, transtibial nmputa- tion, videoj~~oroscopy.

This material i$ based upon work st~pported b) the Department of Veterans Affairs Rehabilitation Research and Development Service, Washington, DC 20420.

Addre\\ a11 ~orre\pondence dnd reque\t\ ioi reprint\ to C h r ~ \ t ~ a n R R o ~ o b o MD LOI S San M'iteo D r ~ v e Tte 302 Sdn M,~teo CA 94301

INTRODUCTION

Amputation of a limb is a significant problem despite advances in the medical and surgical manage- ment of some of the underlying etiologies, such as atherosclerotic disease of the lower limbs. The preva- lence of amputation in the United States is approxi- mately 1 million (I) , and another 43,000 new major amputations are performed yearly (2).

Most amputations are performed on the lower limb and occur as a result of complications of diseases; primarily peripheral vascular occlusive disease and diabetes. The person is not only challenged by having to learn to use the artificial limb, but also by the attendant complications that may arise from poor prosthetic fit, including recurrent residual limb breakdown predispos- ing the subject to pain, osteomyelitis, and sepsis. Moreover, abnormal gait with the use of a prosthesis can be unsafe, cosmetically unacceptable, and increase the energy cost of ambulation. Gait deviation with a prosthesis can increase the energy cost of ambulation, risk for falls, and may predispose to the development of osteoarthritis.

Currently, the evaluation of prosthetic fitting and residual limb complications is largely based on the complaints of the subject, and limited objective criteria provided by the examination of the residual limb, prosthesis, and gait pattern. Numerous clinical methods have been used to evaluate socket fit. These include the use of skin pencils, lipstick, chalk, gum, detection of

7

BOCOBO et al . Videofluoroscopy of TTA

redness of the skin, gaps between residual limb andsocket, pressure in the residual limb, and instability (3).Simple observation of gait characteristics by a trainedobserver is clinically useful ; however, there are newprocedures for gait analysis including kinetic andkinematic analysis, electromyographic activity, andenergy consumption (4-8) . Observational gait analysisasks the clinican to concentrate first on one leg in oneprojection and then the other projection . An obviouslimitation is the difficulty in observing multiple eventsconcurrently (9) . Although kinetic information may notbe easily translated into effective rehabilitation practice,kinematic analysis may be used to compare existing gaitpatterns (10) . Current radiographic procedures (plainX-ray and xeroradiography) have only been able toprovide static analysis of the residual limb-socketrelationships . This is inadequate in light of the impor-tance of understanding the inherent dynamic interactionbetween the residual limb and socket (11-13) . Numer-ous procedures have been used for gait analysis asreviewed by Harris, but no radiographic procedure todate has been utilized to evaluate dynamic residuallimb-socket relationships during the different phases ofthe gait cycle (14) . Dynamic studies have the potentialto generate critical data on bone or soft tissue move-ment and different prosthetic components . Fluoroscopyis a dynamic study that has been used to functionallyevaluate swallowing and musculoskeletal disorders (15-17) .

VIDEOFLUOROSCOPYIMAGING SET-UP

Figure 1.Equipment setup for videofluoroscopic imaging of residual limbs.This consists of a treadmill mounted on a platform . The subject ispositioned between the X-ray source and image intensifier . A TVmonitor is used to view residual limb movement while fluoroscopicimages are stored by a video recorder .

The purpose of this pilot study was to develop anew videofluoroscopic techinique to evaluate dynamicresidual limb and socket relationships . Specifically, wesought:

1. to determine the optimum kilovoltage and mil-liamperage settings providing the best resolutionof prosthetic components and amputation residuallimbs;

2. to determine whether manual exposure controlsetting provides better images compared to auto-matic exposure;

3. to identify components of the residual limb orsocket requiring radiographic markers ; and

4. to describe residual limb-socket relationships dur-ing the gait cycle under fluoroscopy.

METHODS

SubjectsIndividuals included in this study were subjects

with transtibial amputation who were seen in ourprosthetic clinic; all were independent communityambulators, and none used assistive devices . To beincluded, subjects had to wear a patellar tendon bearing(PTB) socket, be able to ambulate with use of theprosthesis on a treadmill, and be physically able tocomplete the examination. All subjects had a socketinsert : the Pelite liner was the most frequently used, butthree subjects wore Kemblo inserts . Seven used cuffsuspension, three used rubber sleeve, one usedsuprapatellar/supracondylar suspension, and one used athigh corset/fork strap. Socks worn were of wool . Thosesubjects who developed symptoms, such as severeresidual limb pain, chest pain, dyspnea, or lightheaded-ness, were excluded. Twelve males, aged 39 to 81,fulfilled the criteria to complete our study ; 11 wereunilateral and 1 was bilateral . Most of their amputationswere due to vascular disease, the main diagnoses beingarteriosclerosis sometimes associated to diabetes mel-litus; three were amputated because of trauma . A totalof 16 studies each for anteroposterior (A-P) and lateralviews were performed. A written informed consent wasobtained, and the study was carried out with theapproval of the Human Subjects Committee at StanfordUniversity Medical Center.

Videofluoroscopy EquipmentFigure 1 illustrates the videofluoroscopic imaging

setup. A Siemens Siregraph fluoroscopy machine

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Journal of Rehabilitation Research and Development Vol . 35 No. 1 1998

(Siemens Medical Systems, Inc ., Burlingame, CA) wasutilized . It had an exposure rate of 3 .5 rads/min withoutthe use of a grid in automatic exposure control and 1 .6rads/min at 70 kV manual control . Guidelines forminimizing exposure were followed (18) . Manual andautomatic exposure control modes were used in order tocompare their resolution . Under manual control, threedifferent settings were used : 50, 80, and 110 kV. In 12residual limbs, the optimum kilovoltage and the associ-ated milliamperage settings were recorded and com-pared. A Sony Model V05800 videorecorder (also fromSiemens Medical Systems) was connected to a TVmonitor with a VG-R2 connector. Results were recordedusing a 3/4-in Ampex 187 KCA-60 VHS professionalvideocassette.

ProceduresThree residual limbs were studied statically in A-P

and lateral views in order to identify anatomical andprosthetic components . Coned and wide view fieldswere compared . The same residual limbs were evaluateddynamically by asking the subject to simulate ambula-tion by walking in place on a platform. These prelimi-nary studies were performed initially to identify residuallimb and prosthetic components that were analyzed inthe dynamic study. Leaded rubber markers were utilizedto tag some prosthetic components that could not bereadily identified.

ANTERO-POSTER]OR VIEW

SHANK OF PROSTHESIS

Figure 2.Diagram of the A-P view . Residual limb-socket components anddynamic movements that were analyzed are labeled .

Twelve residual limbs with transtibial amputationwere dynamically studied while subjects ambulated on a9880 Vitamaster Motorized Treadmill (RoadmasterCorporation, Tyler, TX) . This treadmill was mounted ona wooden platform with steps and lockable casters toraise it to a height that allowed the observation of theknee and the distal residual limb in all subjects . Thehandrails of the treadmill were modified to allowadequate viewing of the residual limb and prosthesis.Subjects were asked to come with comfortable clothingand given a trial run without fluoroscopy to getacquainted with the use of the treadmill . They were thenasked to walk at their usual and most comfortablewalking speed with the control set at that level . In somesubjects, leaded rubber markers were placed overdiscrete prosthetic areas within the socket for identifica-tion. Subjects were positioned on the treadmill withinthe view field in such a way that the amputated leg wasclosest to the fluoroscopy table (X-ray source) . A-P andlateral views were obtained under fluoroscopy . Thesewere accomplished by positioning the treadmill relativeto the fluoroscopy unit.

Videotape AnalysisAt completion of the study, the videotapes were

reviewed independently by two investigators (C .B .,LC.) . Since the videorecorder had the capacity forframe-by-frame and slow-motion analysis, we wereeasily able to locate a particular frame for review andreturn to the same point at any time as desired . Anattempt was made to identify relevant parts of theresidual limb, including the patellar tendon, tibialplateau, hamstring tendons, fibular head, and tibialcrest . Similarly, the following prosthetic parts andassociated components were studied: patellar tendonbar, popliteal bulge, hamstring channels, fibular headrelief, tibial shelves, residual limb socks, insert, shank,and socket (see Figures 2 and 3) . Data gathered fromreview of 16 videoflouroscopic studies in A-P andlateral views by both investigators were tabulated . Thepercentage agreement of visualizing a particular residuallimb or prosthetic component out of a total of 16residual limbs was then determined.

Statistical MethodsA chi-square test was used to determine the

concordance in the visualization of components betweenobservers . A continuity correction was applied, and anexact test when considered appropriate (19,20) . Testresults are presented in Table 1.

4

SOCKETINSERT

STUMPFIBULATIBIADISTANCE BETWEENTIBIA & FIBULA (B)

PISTON ACTION (A)

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BOCOBO et al . Videofluoroscopy of TTA

Table 1.Videotape analysis of residual limb and prosthetic components.

Anteroposterior view Lateral view+ — +1— X2 -test + +1— X2-test

RESIDUAL LIMBPatellar tendon 0 16 0 NS 9 7 0 NSHamstring tendons 0 16 0 NS 0 15 1 NSFibular head 14 2 0 NS 2 14 0 NSSoft tissue edge 13 2 1 NS 13 2 1 NSTibial crest 1 15 0 NS 13 2 1 NSTibial flares 15 1 0 NS 0 16 0 NS

PROSTHESISResidual limb socks 4 10 2 NS 0 16 0 NSInsert 12 2 2 NS 8 7 1 NSPatellar tendon bar 5 11 0 NS 14 2 0 NSPopliteal bulge 0 16 0 NS 13 2 1 NSHamstring channels 0 16 0 NS 0 16 0 NSFibular head relief 8 7 1 NS 0 15 1 NSTibial shelves 12 4 0 NS 0 16 0 NSShank 6 10 0 NS 2 14 0 NSSocket 13 3 0 NS 10 6 0 NS

+ = agreement by both researchers in visualization of residual limb and prosthetic components ; — = agreement by both researchers in nonvisualization ofresidual limb and prosthetic components ; +/— = disagreement ; NS = no significant difference between both researchers in visualization (p=0 .05) Numbersindicate number of cases studied . An X2-test with continuity correction was used when considered appropriate.

RESULTS

OverviewThe initial three subjects studied under static

conditions without the treadmill showed that, comparedto the coned projection, the wide projection provided a

KNEE FLEXION EXTENSION (B)better view field for visualizing the amputation residuallimb and prosthesis . Percentage of agreement between

1'~t

)

.– SOCKETobservers for the residual limb parts visualized in the

/

INSERTA-P and lateral views was 98 percent with a range of 94 STUMPto 100 percent . For the prosthetic components, average TIBIA FIBULAagreement was 97 percent with a range of 87 to 100percent. Interater ability in components visualization isreported in Table 1 . The visualization was performedseparately by each researcher. There were no statisti-

ANTERO-POSTERIORcally significant differences . One subject had a short

STUMP MOTION (A)

residual limb with adequate visualization of the distallimb segment and socket with insert at 80 kV (manualcontrol) . Generally, fewer than 50 gait cycles wererequired to complete each study . The average recording

Figure 3.time was 40 s . It took an average of 20 min for each

Diagram of lateral view . Residual limb-socket components andobserver to review a study in A-P and lateral views .

dynamic movements that were analyzed are labeled.

LATERAL VIEW

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Journal of Rehabilitation Research and Development Vol . 35 No. 1 1998

50

60

70

80

90

100

110KILOVOLTAGE

2-

1 .8 •

1 .6

1 .4 -

1 .2 •

1-

.8-

.6-

.4-

.2-0 -

50

60

70

80

90

100

110KILOVOLTAGE

Figure 4.Graph of kilovoltage settings providing the best visualization plottedagainst milliamperage settings . Top: Best visualization was achievedin the 80-110 kV range during manual setting (A-P view) . Bottom:Best visualization was achieved in the 80-100 kV range duringmanual setting (lateral view) . °=manual setting ; '*=automaticsetting.

Videofluoroscopy SettingsThe manual exposure control provided better

resolution than automatic exposure control in the vastmajority of our subjects. These were found to begenerally in the 80 to 110 kV range (mean values : 86.3kV in A-P view, 88.9 kV in lateral view) . The 50 kVsetting offered good resolution in only one subject . Theresults of kilovoltage settings plotted against mil-liamperage settings are presented in Figure 4.

Components in Anteroposterior ViewTable 1 indicates the percentage breakdown of

residual limb and prosthetic components identified by

videofuoroscopy . In the A-P view, the fibular head andtibial flares were identified . Only the residual limb edgewas appreciated when studying the soft tissue elements.The insert and tibial shelves were demonstrated in mostsubjects . Socks were occasionally seen . Folding of thesocks was noted with piston action . The patellar tendonbar and fibular head relief of the socket were visualizedin fewer than 50 percent of the studies . These parts willrequire leaded rubber markers.

Components in Lateral ViewIn the lateral view, the tibial crest and patellar

tendon were appreciated in most subjects . In addition,the popliteal bulge and patellar tendon bar were seen . Itwas not possible to appreciate the hamstring channels orthe socks . In this projection, leaded rubber markers maybe needed to identify the hamstring tendon channel,residual limb socks, and insert.

Additional FindingsImpacting of the tibia against the anterior wall

during stance phase was seen in three subjects whoclinically expressed moderate complaints when walking.Lateral thrust was appreciated in three . One of themcomplained of distal residual limb pain; redness wasnoted in the lateral aspect of the residual limb . Otherfindings included: soft tissue rolling, loss of congruencybetween the fibular head and socket relief, and rollingof socks and/or soft tissues . The shank could be viewedeasily in A-P and lateral projections when it came intothe visual field. Additional prosthetic components visu-alized included the distal end pad, prosthetic hardware,popliteal bulge, tibial shelves, strap buckles, and elasticsleeve (Figures 5 and 6).

Case ReportsTwo dynamic studies are described to illustrate the

use of this radiographic procedure:

Case 1RS, a 67-year-old male with left transtibial amputa-

tion came to our clinic with complaints of pain in theresidual limb during ambulation. He had used a PTBsocket with cuff suspension, Kemblo insert (with foamrubber and leather) for the past 3 years . He was aprevious user of the Kemblo liner due to its excellentdurability . Examination of the residual limb revealedredness in the lateral aspect extending from 3 cm belowthe fibular head to the distal end . The insert had wornout near the patellar tendon bar and corresponding tibial

.8-

.6-

.4-

.2-

0

0

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BOCOBO et al . Videofluoroscopy of TTA

crest area . Videofluoroscopy revealed lateral motion ofthe residual limb during stance phase . Recordings alsoindicated significant piston action after review of bothswing and stance phase . Leaded rubber markers indi-cated loss of congruency between the fibular shelf andits relief (Figure 5a) . Significant air gaps were notedduring the gait cycle at the distal end of the socket.Manual exposure provided better images.

Case 2JH, a 66-year-old male with left transtibial amputa-

tion came to our clinic with complaints of persistentdistal pain in the residual limb. No bony or soft tissuepathology was noted on static plain films . He had someredness noted in the distal residual limb . Prostheticcheckout was essentially normal including gait pattern.Videofluoroscopy revealed adequate residual limb-socket relationships between pressure-sensitive areas ofthe residual limb and the socket. However, the subjecthad rolling of soft tissues during stance phase (Figure6d).

DISCUSSION

Methodological ConsiderationsVideofluoroscopy is used for evaluating other

conditions like swallowing and musculoskeletal disor-ders (15-17) . Although it gives a slightly reducedresolution compared to cinefluorography, most clini-cians and researchers choose to use videofluoroscopydue to significantly reduced radiation exposure . Ingeneral, at 25 rads or less, ordinary laboratory andclinical methods will show no indications of injury . Asingle test for our study delivers a radiation dose of onlyabout 1 .9 rads, which is of no clinical significance (18).This is a minimal amount of radiation exposure in lightof the potential benefits from the study as previouslydiscussed. Other advantages of videofluoroscopy in-clude immediate playback after recording, a techniqueless expensive than motion picture film recording . Anelectric treadmill, videorecording system, and TV moni-tor are not expensive, and they can be easily connectedto a hospital fluoroscopy unit . This system also allowsreal-voice recording of both subject and examiner.

Technical DifficultiesOne limitation of this technique was the overlap of

the residual limb with the full limb in the lateral view.This made it difficult to view the residual limb-socket

Figure 5.

Videoframes of residual limbs (A-P view), a : Loss of congruencybetween fibular head and fibular head relief due to pistoning . Theproximal leaded rubber marker in the lateral wall is the fibular headrelief of the socket, indicating that the residual limb has sunk downinto the socket . b and c: Piston action also indicated by difference inlocation of patellar tendon bar marker relative to the knee jointduring swing phase and stance phase, respectively . d: Abnormalseparation between tibia and fibula indicates interruption ofinterosseous membrane following surgery.

Figure 6.

Videoframes of residual limbs (lateral view) . a : ilyperextension ofthe knee joint was demonstrated in this study . b: Patellar tendon bar(indicated by the leaded rubber marker) . The ideal location ismidpoint between inferior pole of patella and tibial tubercle . c : Tibiais superficial with minimal soft tissue protection (arrow) making itprone to residual limb breakdown . Radioluscent outline indicatesinsert. d : Arrow indicating rolling of soft tissues .

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Journal of Rehabilitation Research and Development Vol . 35 No . 1 1998

interface for a brief period during mid-swing, althoughthis is not likely a time of distress . It was also necessaryto reposition the subject and imaging unit due to thelimited view field in the lateral view . This allowed us toview and record the entire gait cycle . It is alsoconceivable to connect the platform supporting thetreadmill to the videofluoroscopic unit and remotelycontrol subject position during the test.

Other soft tissue structures (i .e ., hamstring tendonsand patellar tendon) were sometimes difficult to visual-ize. This may be due to a poor signal-to-noise ratio andan increased level of scattered radiation resulting in alow quality of the image . We feel that the use of leadedmarkers would enhance the accuracy of identifyingcertain anatomic and prosthetic components.

Clinical RelevanceA goal of rehabilitation for the person with a

transtibial amputation is to provide a safe, pain-free,energy efficient, and cosmetically acceptable use of theprosthesis . Achieving this goal is largely dependent onproper prosthetic fit, accomodating anatomical charac-teristics of the residual limb, and achieving satisfactorydynamic residual limb-socket relationships during thegait cycle.

Kinematic analysis comparing nonimpaired indi-viduals with subjects with transtibial amputation canhelp the clinician to modify the movement pattern of theprosthetic limb to one closer to normal gait (21).However, as the displacements described are minimaland studied parts are hidden from the usual view, thereare limitations attached to attempts at clinical measure-ment. Nevertheless, such measurement is necessary ifcomprehensive investigation of the mechanics associ-ated with the correct fitting of the prosthesis is to beundertaken . X-rays and xerograms can provide impor-tant information about bony elements, blood vesselcalcification, and soft tissues as well as prosthetic fit(6) . However, they do not provide information about thedynamic relationships between the residual limb andsocket . The study of residual limb-socket interfacerequires an imaging technique that allows the identifica-tion of functional landmarks in three dimensions thatcan be followed by measurements of residual limbmotion. Videofluoroscopy may overcome these difficul-ties by making it possible for the observer to visualizethe A-P, lateral, and axial movements of the residuallimb relative to the socket . This preliminary studysuggests that videofluoroscopy has the potential for

offering information of clinical value that is notcurrently available.

There have not been, to our knowledge, previousvideofluoroscopic investigations of residual limb-socketrelationships in subjects with transtibial amputation.Therefore, there are no standards with which thefindings in our subjects can be compared.

Future StudiesAt this time, this procedure is still a research tool

and possibilities of clinical application are not yetevident . Data from videofluoroscopy can be incorpo-rated in the basic science field of amputationbiomechanics . Research along these lines may alsogenerate new radiographic criteria for diagnosing vari-ous causes of residual limb pathology, poor prostheticfit, and gait deviations in persons with amputation.Normative data derived from future studies can providea basis for improving the design of new sockets as wellas the evaluation of newer prosthetic devices in terms offitting and subject comfort. Videofluoroscopy also hasthe potential to be a diagnostic procedure for assessingthe effectiveness of prosthetic readjustment or modifica-tion in the management of fitting problems . Long-termfollow-up of subjects fitted with their prostheses withthe assistance of videofluoroscopy can also be investi-gated in future studies . It could be a useful toolsupplementing other methods utilized for gait analysis(22).

ACKNOWLEDGMENTS

We gratefully acknowledge support for this re-search from B . Iwai, RT, who provided advice for theradiologic technique, and to K . Lee for his advice in thedesign of this project.

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