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Gait cycle.A gait cycle was from paw tou ch of one forepawto paw touch ofthe ipsilateral forepaw.

Function during gait.The functions during gait were peakextension during gait, time to peak extension, peak flexionduring gait, and time to peak flexion.

Peak extension during gait.During th e stance phase of gait,the dog's forepaw m oves dorsally in relation to the antebrac h-ium. The greatest angle observed between the antebrachiumand the forepaw was recorded as peak extension during gait.

Time to peak extension.The time from paw touch to peakextension of the carpal joint was considered the amount oftime required to reach peak extension.

Peak flexion during gait.During w alking, the carpal jointof the dog moves from the zero position in late stance towardflexion during swing. The greatest amount of flexion wasconsidered peak flexion during gait.

Time to peak flexion.The time from paw touch to peakflexion of the carpal joint w as considered the am ount of timerequired to reach peak flexion.

Traction.Traction w as administered manually by fixatingone joint surface while the othe r joi nt surfacewas pulled alongits longitudinal axis, moving it perpe ndicularto the fixed ointsurface.13

Gliding.Glidingwas administered manually by fixating on ejoint surface and moving the other joint surface parallel tothe fixed oint surface in either a ventral or dorsal direction.

M E T H O D

Because no metho d of evaluating join t mo bilization therapyappears to be rep orted in th e literature, I devised the followingmethod using dog carpal joints. Twelve mongrel dogs wereobtained from the Animal Care Unit of the University ofIowa. After the dogs were dipped in a chlorinated solution tocontrol parasites, I selected the dogs based on specific criteria.

Each dog selected was male, at least1 year of age (determinedby the presence of plaque and tartar on the teeth), 15 to 18kg in weight, docile enough to lie on the floor during PROMmeasurement and mobilization treatment of the right carpaljoint, and willing to walk beside me with choke collar andleash. Each dog was immu nized for hep atitis and distemper,assigned a num ber, and quarantined for one week. The dogswere housed in cages 84 cm wide, 72 cm deep, and 34 cmhigh and were fed a com mon diet with water ad libitum.

Measurements

After selection of the dogs, PROM was measured using a

goniom eter. Each dog was laid on its left side and th e PR OMwas measured to the ne arest degree for the right and left carpaljoints. Three m easurements were obtained for each joint, a ndthe mean was recorded as the initial PROM for each dog. Iobtained all measurements throughou t the study.

In the laboratory, each dog was placed on its left side. Astrap with three holes was placed on the medial aspect of theanimal's left forelimb with the center hole over the carpaljoint line, depicting the joint axis for flexion and extension.Animal-marking chalk was used to make three dots on thedog's limbone dot on the carpal joint line and the others10 cm proximal to and 4 cm distal from the dot overthe jointline. The same process was completed for the right forelimb,

except that the dots were placed on the lateral aspect of thelimb.

The dogs were walked six to eight lengths ofthe walkwaywith their walking velocity controlled by an overhead m otorized track set at 4 km/hr. On the 9th and 10th lengths, avariable-speed, 16-mm camera* recordedthe dog's gait at 160frames/sec. A one-second clock (360/sec) and a 10-cm gridwere positioned perpendicular to the camera (Figs. 1, 2).

The processed film of one gait cycle for each dog wasanalyzed using a Vanguard motion analyzer. The motionanalyzerwas used to record the X and Y coordinates ofeachof the three dots in every frame of one gait cycle for the rightand left forelimbs. Using the X,Y coordinates for each dot,the line connecting the dot on the joint line to the proximaldot (vector A), and the line connecting the dot on the jointline to the distal dot (vector ), I used the equation for thedot product of two vectors

. = AB cos (, )

to determine the carpal joint angle for every .00625 second(1/160 second) of the dog's gait cycle. In addition to the peakjoint angles of extension and flexion, the amount of timerequired to reach these angles was determined by the cinematographic analysis.

Immobilization

After the initial evaluation, the right carpal joint of eachdog was immobilized for six weeks. The dog's forelimb waswrapped with cotton cast padding, and a thermoplastic splintwas molded around the limb. For added security, the splintwas wrapped w ith adhesive tape. The carpal joints of 10 dogswere immobilized in 25 degrees of flexion, and the joints of2 dogs were immobilized in 45 degrees of flexion. The shorterlimb lengths required a greater degree of flexion to preventthe splint from sliding off the dog's limb. The splints werechecked daily to ensure that they were secure and that theywere causing no adverse effects to the dogs' limbs. The dogs

were taken from their cages only when an adjustment of thesplint was necessary. During th is phase of the study, th e dogswere assigned randomly to either Treatment or ControlGroups.

Remobilization

After the six-week immobilization period, the splints wereremoved and all 12 dogs were reevaluated as described previously. The dogs in the Co ntrol Gro up (n = 6) were removedfrom theircages only for a goniome tric and a cinema tographicevaluation o nce weekly for four weeks. Each dogwas checkeddaily, as during the immobilization period. The dogs in theTreatment G roup (n = 6) were removed from their cages atthe same time each day for 28 consecutive days. The dogswere placed in a reclining or sitting position on th e floor neartheir cages, and mobilization treatment was administered tothe right carpaljoint. They also were evaluated by the goniometric and cinematographic methods once weekly for fourweeks. A ll of thedogs were carried when theywere transportedfrom their cages to the laboratory and when they were returned, thus, the only walking they performed during thefour-week remobilization period was in the laboratory and intheir cages.

* LoCam, Red Lake Corp, 2991 Corrin Dr, Santa Clara, CA 95051. Vanguard Instrument Corp, Walt Whitman Rd, Melv ille, N Y 11746.

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The mobilization treatment I administered to the dogs inthe Treatment Group consisted of traction and dorsal andventral gliding of the right carpal joint. The oscillatory technique described by Maitland 11 was used. I grasped and stabilized the radius and ulna just proximal to the carpal boneswith my left hand, and with my right hand, I grasped the pawjust distal to the carpal bones. The carpal joint was flexed tothe limit of PROM without any forced motion. A smooth,regular oscillatory motion was applied at the end of the

available PROM for traction, followed by dorsal and ventralgliding. The treatment sequence I used consisted of three setsof 20 oscillations of traction and dorsal and ventral glidinga total of 60 oscillations of each movement. The oscillationswere administered at the rate of one to two a second andtimed with a stopwatch, requiring 12 to 13 seconds to complete the 20 oscillations of each set. The total time requiredto complete each mobilization treatment session, therefore,was 1.8 to 2 minutes. The total time required to remove thedog from its cage, apply the mobilization treatment, andreturn the dog to its cage was 5 to 10 minutes each treatmentsession.

Re l i ab i l i ty

The reliability of recording the cinematographic data wasaccomplished by filming all 12 dogs on two separate occasions, with a minimum of eight hours between recordings,and analyzing the separate gait cycles for each dog. The test-retest reliability coefficients of .91 or higher for the functionduring gait measures suggest a highly reproducible laboratoryprocedure.

To determine my reliability of recording the X,Y coordinates using the Vanguard m otion analyzer, the same gait cyclefrom each of the 12 dogs was analyzed on two different days.The test-retest data reliability coefficients of .95 or higher for

the functions during gait suggest highly reproducible datausing the motion analyzer.The PROM of all 12 dogs' right and left carpal joints was

measured on two different days. The test-retest data variabilitywas low with a standard deviation of 1.4 degrees. Low variability also was noted with a range of 149 to 154 degrees offlexion. The reliability coefficients were .76 and .68 for theright and left carpal joints, respectively.

All test-retest data were obtained before the immobilizationperiod. To avoid influencing restoration of joint motion, noduplicate measurements or cinematographic analyses wereconducted during the remobilization period.

Valida t ion o f L im b Segm en t Leng th M easurem entBecause the determination of the carpal joint angle was

based on a vector analysis of a sagittal view of the dog'sforelimb, the effect of the limb's movement in and out of thefilm plane on measurement accuracy was a point of concern.The determination of the limb segment length variability andstatistical comparison of limb segment length measurementsat specific points during the gait cycle appeared to be anappropriate method to validate the sagittal plane measurement technique. The proximal and distal limb segment lengthmeasurements were obtained from the preimmobilization,postimmobilization, and two-week remobilization gait filmsfor the right and left forelimbs of 10 dogs. Four positionsduring the gait cycle were used: paw touch, peak extension,peak flexion, and paw touch, which include the positions

Fig. 1. Schematic of physical therapy laboratory.

Fig. 2. Dog on walkway.

from which carpal joint angle determinations were calculated.The right limb segment length data were analyzed using ananalysis of variance to determine whether any differencesexisted at the 05 level of significance. AnF ratio of .60 forthe right proximal limb segment data and .50 for the distallimb segment data (F - 5.14; df= 2,6, p = NS) indicated nosignificant differences. Because the left limb segment datawere comparable to the right imb segment data, no statisticalanalysis was performed. On the basis of these data, I concluded that the minimal movement of the dog's limb in orout of the film plane did not affect appreciably the limbsegment length measurements from which the carpal jointangle calculations were made.

Joint Sim ula t ionBecause several authors 11,13,16,22have stated that application

of joint m obilization treatment is an acquired skill and thatit should be applied in a consistent manner, a method ofpracticing traction and gliding movements was devised. Aproving ring with four strain gauges was placed between twodoor hinges. One hinge was fixed to a tabletop, and the otherwas equipped with a sponge pad about the same diameter asa dog's forepaw. The signal from the proving ring was recordedon a strip chart recorder (Fig. 3).

Because gentle mobilization treatment is advocated, 11

movements with 1-, 2-, 3-, and 4-kg forces were practicedbefore the remobilization of the dogs' right carpal joints andonce a week during the remobilization period to monitorretention of the skill. In addition to practicing to gain skill in

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TABLEPassiv e Ra nge of M otion a nd Function During Gait Before and After Im m obil izat ion of Do gs' Right Carpal Join ts

Function

Passive range of motion ()Peak extension during gait ()Time to peak extension (sec)Peak flexion during gait ()Time t o peak flexion (sec)

Preim m obilization

Treatment Group(n = 6)

152.028.2

0.1798.2

0.43

s

1.47.40.07

10.00.07

Control Group(n = 6)

153.021.3

0.1191.3

0.34

s

0.813.50.03

15.20.09

Postimm obilization

Treatment Group(n = 6)

99.2- 5 . 2a

0.1461.8

0.38

s

7.48.40.04

18.30.1

Control Group(n = 6)

s

113.0 6.54.5 5.30.13 0.05

85.0 4.20.32 0.06

aIndicates unable to extend.

Fig. 3. Joint simulator.

applying a constant force, oscillatory motions were practiced

at a rate of one to two per second. One sequence of movements consisted of three sets of 20 oscillations of traction,followed by dorsal and ventral gliding.

I practiced this technique while observing the paper chartrecord. After I became familiar with the amount of effortneeded to produce each of the motions at the desired forceand rate, I practiced the mobilization treatment while notobserving the record. Means and standard deviations calculated for several practice sessions before remobilization andthe weekly sessions during the remobilization period indicatedthat the mobilization treatment could be applied with 10%accuracy.

Data A na lys isDuring the remobilization period, one dog died of unknown

causes and a second dog became ill. Both dogs were from theControl Group. The analysis, therefore, was based on the dataof four Control Group dogs and six Treatment Group dogs.

The data obtained immediately after the six weeks of immobilization suggested that the Treatment and ControlGroups were not affected equally by the immobilization eventhough they were statistically equivalent initially (Table). Thisresult was unexpected and to verify my observation, I performed a t test at the .05 level of significance to compare thepreimmobilization and postimmobilization data of the Treatment and Control Groups. The preimmobilization and post-immobilization data were statistically different. To remove,by regression, the recognized differences between the Treat

ment and Control Groups, an analysis of covariance (AN-COVA) at the .05 level of significance was applied to theremobilization data w ith the postimmobilization data as thecovariate.

An ANCOVA provided three comparisons. The treatmentcomparison was between the Treatment and Control Groupsacross all four weekly evaluations. The time comparison wasamong the four time intervals. If this comparison was signif-icant, I used the Tukey's w multiple comparison procedureto determine where the differences existed among the fourweekly evaluations. The third comparison was the time-treatment interaction and is referred to as the simple effects.

RESULTS

The measurements of the left carpal joint were not statistically significant. Passive range of motion, peak extension, andpeak flexion during gait were found to be statistically significant for the right carpal joint.

Pass ive Range o f M otion

The treatment and the time comparisons were significantat the .05 level for the PROM of the right carpal joint. Thetreatment comparison made was between the Treatment andControl Groups across all four postimmobilization evaluations; that is, the means of all four evaluations for the Treatment and Control Groups were statistically different. Themean across all four evaluations for the Treatment Groupwas 140 degrees and for the Control Group 138 degrees. Thetime comparison was made among the four weekly timeintervals (eg, comparing Week 1 with Week 2) using theTukey's w multiple-comparison procedure. This comparisoncombined the Treatment Group and Control Group data andrevealed that the mean of the Week 1 postimmobilizationevaluation (124.2) was less than that of the Week 2 evaluation(137.1) that was less than that of the Week 4 evaluation(149.8); the mean of the Week 1 poststimulation evaluationwas less than that of the Week 3 evaluation (145.3).

I found no time-treatment interaction and, therefore, theseresults do not provide a clear statistical inference regardingthe difference between the Treatment and Control Groups. Iencourage the reader to interpret cautiously the trend of theTreatment Group to gain PROM more quickly over timethan the Control Group (Fig. 4).

Peak Extension During Gait

The time comparison was significant at the .05 level for thepeak extension during gait of the right carpal joint. A Tukey's

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Fig. 4. M ean passive ran ge of m otion of t reated and control do gs'right carpal joints.

w procedure was used to determine whether differences existed among the four weekly evaluations. This test revealedthat the mean of the Week 1 postimmobilization evaluation(9.9) was less than that of the Week 3 evaluation (18.9).Because this statistically significant time comparison does notshed much light on the comparison between the Treatmentand Control Groups, I encourage the reader to interpretcautiously the trend of the Treatment Group to increase peakextension at a faster rate than the Control Group (Fig. 5).

Pe a k F l e x i o n Du r i n g Ga i t

The time comparison was significant at the .05 level for thepeak flexion during gait of the right carpal joint. A Tukey's wprocedure, however, indicated that no differences existedamong the means of the four weekly eva luations. Nevertheless, it is possible mathematically that a significant F ratiomay result in an insignificant finding with a Tukey's w procedure, particularly with a small sample size.

The graphical description (Fig. 6) o f peak flexion shows asteady rate of improvement for the Treatment Group. TheControl Group shows a further loss of motion during the firstweek after immobilization before an increase in motion isobserved.

DISCUSSION

Developing a new method usually involves some pitfallsand needed changes even though the basic methodology appears to be satisfactory. This study proved to be no exception.

The immobilization procedure did render the dog carpaljoints hypomobile, which is in agreement with many authorsusing various animal m odels. 23-29 The reason that the Controland Treatment Groups did not have equivalent stiffness afterthe six weeks of immobilization is unclear. I speculate, however, that using dogs with unknown pedigrees provided greatvariability. This speculation is supported by the death of one

dog and illness of a second. Another factor that must beconsidered is the dog's limb length. Two dogs required greaterflexion of the carpal joint to allow the splint to be secure.

Fig. 5. M ean peak extensionduring gait oftreated and control do gs'right carpal join ts.

Fig. 6. M ean peak flexion during gait of treated an d control do gs'right carpal joints.

Even though the variability among the dogs apparently was acritical factor, it is a component of the method that can becorrected in future investigations. The availability of a sampleof common-pedigree dogs is primarily a factor of cost.

The method I used was adequate to produce a hypomobile

joint from an otherwise normal joint, to record measurementsof PROM and function during gait, and to establish a procedure for practicing mobilization treatment. The results that Iobtained should be interpreted with caution, however, because a rigorous statistical procedure was applied to a variableand small sample. The study, nevertheless, appeared to produce evidence that the treated dogs did demonstrate a fasterrate o f change as a result of the mobilization treatment (Figs.4-6). This finding may be explained by my hypothesis thatthe handling and subsequent movement of the periarticulartissues during mobilization treatment influences joint mobility. This speculation appears to be plausible because 2 to 12weeks of immobilization has been shown to decrease thewater content, in addition to the concentration of the glyco-saminoglycans, of these tissues by4% to 6% of normal.27 Thedecrease in the synthesis and, therefore, concentration of these

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