the initial effects of an elbow mobilization with movement technique on grip

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Original article The initial effects of an elbow mobilization with movement technique on grip strength in subjects with lateral epicondylalgia J. H. Abbott, C. E. Patla, R. H. Jensen Institute of Physical Therapy, University of St. Augustine for Health Sciences, St. Augustine, Florida, USA SUMMARY. This preliminary study indicates the proportion of patients with lateral epicondylalgia that demonstrate a favourable initial response to a manual therapy technique – the mobilization with movement (MWM) for tennis elbow. Twenty-five subjects with lateral epicondylalgia participated. In a one-group pretest – post-test design, we measured (1) pain with active motion, (2) pain-free grip strength and, (3) maximum grip strength before and after a single intervention of MWM. Results of the study indicate that MWM was effective in allowing 92% of subjects to perform previously painful movements pain-free, and improving grip strength immediately afterwards. Significant differences were found between the grip strength of the affected and unaffected limbs prior to the intervention. Both pain-free grip strength and maximum grip strength of the affected limb increased significantly following the intervention. Pain-free grip strength increased by a greater magnitude than maximum grip strength. It can be concluded that MWM is a promising intervention modality for the treatment of patients with Lateral Epicondylalgia. Pain-free grip strength is a more responsive measure of outcome than maximum grip strength for patients with Lateral Epicondylalgia. Further research is warranted to investigate the long-term effectiveness of MWM in the treatment of impairment and disability resulting from Lateral Epicondylalgia. # 2001 Harcourt Publishers Ltd. BACKGROUND AND SIGNIFICANCE Lateral epicondylalgia (LE) is a condition with complex aetiological and pathophysiological factors. LE is characterized by pain at the lateral aspect of the elbow, commonly associated with resisted wrist or finger extension and gripping activities (LaFreniere 1979; Kushner & Reid 1986; Wadsworth et al. 1989; Yaxley & Jull 1993; Noteboom et al. 1994; Stephens 1995; Vicenzino & Wright 1996). LE is also known as: lateral epicondylitis, lateral epicondylosis, tennis elbow, or tendonitis of the affected forearm extensor muscles (e.g. extensor carpi radialis brevis tendonitis) (Noteboom et al. 1994; Vicenzino & Wright 1996). The preferred nomenclature is lateral epicondylalgia, as the suffix ‘-algia’ denotes pain; the pathophysiol- ogy of the condition is less commonly inflammation (‘-itis’) or degeneration (‘-osis’) than it is predomi- nantly hyperalgesia and pain (‘-algia’) (Vicenzino & Wright 1996). Mobilization with movement (MWM) is a system of manual therapy interventions developed by Brian Mulligan which combine a sustained manual ‘gliding’ force to a joint with concurrent physiologic (osteo- kinematic) motion of the joint, either actively performed by the patient, or passively performed by the operator (Mulligan 1992; 1993; 1995). The manual force, or mobilization, is theoretically in- tended to cause repositioning of ‘bony positional faults’ (Mulligan, 1993). The intent of MWMs is to restore pain-free motion at joints which have painful limitation of range of movement (ROM) (Mulligan 1995). Therein lies one of the key aspects of the mobilizations with movement system: a trial of MWM at the time of the initial patient examination will determine whether MWM is an appropriate therapeutic intervention for that patient’s dysfunc- tion. If a trial of MWM is able to eliminate the pain Received: 10 October 2000 Revised: 25 April 2001 Accepted: 11 May 2001 J. Haxby Abbott, MScPT, DipPhty, MTC, MNZCP, Assistant Lecturer, Department of Anatomy and Structural Biology, University of Otago, PO Box 913, Dunedin, New Zealand, Catherine E. Patla, PT, DHSc, OCS, Associate Professor, University of St. Augustine for Health Sciences, Richard H. Jensen, PhD, PT, Professor, University of St. Augustine for Health Sciences. Correspondence to: JHA. Tel.: +64 3 479 5145; fax: +64 3 479 7254; E-mail: [email protected] 163 Manual Therapy (2001) 6(3), 163–169 # 2001 Harcourt Publishers Ltd doi:10.1054/math.2001.0408, available online at http://www.idealibrary.com on

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Page 1: The Initial Effects of an Elbow Mobilization With Movement Technique on Grip

Manual Therapy (2001) 6(3), 163–169# 2001 Harcourt Publishers Ltddoi:10.1054/math.2001.0408, available online at http://www.idealibrary.com on

Original article

The initial effects of an elbow mobilization with movement technique on grip

strength in subjects with lateral epicondylalgia

J. H. Abbott, C. E. Patla, R. H. Jensen

Institute of Physical Therapy, University of St. Augustine for Health Sciences, St. Augustine, Florida, USA

SUMMARY. This preliminary study indicates the proportion of patients with lateral epicondylalgia that

demonstrate a favourable initial response to a manual therapy technique – the mobilization with movement

(MWM) for tennis elbow. Twenty-five subjects with lateral epicondylalgia participated. In a one-group pretest –

post-test design, we measured (1) pain with active motion, (2) pain-free grip strength and, (3) maximum grip

strength before and after a single intervention of MWM. Results of the study indicate that MWM was effective in

allowing 92% of subjects to perform previously painful movements pain-free, and improving grip strength

immediately afterwards. Significant differences were found between the grip strength of the affected and unaffected

limbs prior to the intervention. Both pain-free grip strength and maximum grip strength of the affected limb

increased significantly following the intervention. Pain-free grip strength increased by a greater magnitude than

maximum grip strength. It can be concluded that MWM is a promising intervention modality for the treatment of

patients with Lateral Epicondylalgia. Pain-free grip strength is a more responsive measure of outcome than

maximum grip strength for patients with Lateral Epicondylalgia. Further research is warranted to investigate the

long-term effectiveness of MWM in the treatment of impairment and disability resulting from Lateral

Epicondylalgia. # 2001 Harcourt Publishers Ltd.

BACKGROUND AND SIGNIFICANCE

Lateral epicondylalgia (LE) is a condition withcomplex aetiological and pathophysiological factors.LE is characterized by pain at the lateral aspect of theelbow, commonly associated with resisted wrist orfinger extension and gripping activities (LaFreniere1979; Kushner & Reid 1986; Wadsworth et al. 1989;Yaxley & Jull 1993; Noteboom et al. 1994; Stephens1995; Vicenzino & Wright 1996). LE is also knownas: lateral epicondylitis, lateral epicondylosis, tenniselbow, or tendonitis of the affected forearm extensormuscles (e.g. extensor carpi radialis brevis tendonitis)

Received: 10 October 2000Revised: 25 April 2001Accepted: 11 May 2001J. Haxby Abbott, MScPT, DipPhty, MTC, MNZCP, AssistantLecturer, Department of Anatomy and Structural Biology,University of Otago, PO Box 913, Dunedin, New Zealand,Catherine E. Patla, PT, DHSc, OCS, Associate Professor,University of St. Augustine for Health Sciences,Richard H. Jensen, PhD, PT, Professor, University of St. Augustinefor Health Sciences.Correspondence to: JHA. Tel.: +64 3 479 5145; fax: +64 3 479

7254; E-mail: [email protected]

163

(Noteboom et al. 1994; Vicenzino & Wright 1996).The preferred nomenclature is lateral epicondylalgia,as the suffix ‘-algia’ denotes pain; the pathophysiol-ogy of the condition is less commonly inflammation(‘-itis’) or degeneration (‘-osis’) than it is predomi-nantly hyperalgesia and pain (‘-algia’) (Vicenzino &Wright 1996).

Mobilization with movement (MWM) is a systemof manual therapy interventions developed by BrianMulligan which combine a sustained manual ‘gliding’force to a joint with concurrent physiologic (osteo-kinematic) motion of the joint, either activelyperformed by the patient, or passively performed bythe operator (Mulligan 1992; 1993; 1995). Themanual force, or mobilization, is theoretically in-tended to cause repositioning of ‘bony positionalfaults’ (Mulligan, 1993). The intent of MWMs is torestore pain-free motion at joints which have painfullimitation of range of movement (ROM) (Mulligan1995). Therein lies one of the key aspects of themobilizations with movement system: a trial ofMWM at the time of the initial patient examinationwill determine whether MWM is an appropriatetherapeutic intervention for that patient’s dysfunc-tion. If a trial of MWM is able to eliminate the pain

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164 Manual Therapy

associated with an active movement, then MWM isan appropriate intervention; if not, then MWM is notan appropriate intervention. In the event that a trialof MWM is not able to eliminate the pain associatedwith an active movement, the therapist should notemploy the MWM, and other therapeutic interven-tions should, therefore, be explored (Mulligan 1992,1993, 1995; Vicenzino & Wright 1995; Exelby 1996;Hetherington 1996; O’Brien & Vicenzino 1998).

The specific MWM utilized in this study was ‘theMWM for tennis elbow’ described by Mulligan(1992). The technique involves a laterally directedgliding force to the ulna of the affected extremity,with the humerus stabilized, while the patientconcurrently performs an active, pain-free, wristmovement. The active movement utilized is deter-mined by establishing a ‘comparable sign’. A compar-able sign is a movement that reproduces the patient’slateral elbow pain. This is established at the initialexamination, prior to the application of the MWM.For LE, this is typically either making a fist, grippingan object, wrist extension with or without radialdeviation (resisted or unresisted), or extension of themiddle and/or index fingers (resisted or unresisted)(LaFreniere 1979; Kushner & Reid 1986; Wadsworthet al. 1989; Yaxley & Jull 1993; Noteboom et al.1994; Mulligan 1995; Stephens 1995; Vicenzino &Wright 1996).

Since the publication of this technique, only threepublished reports are available which document theuse of this MWM in LE patients: a single-case study(Vicenzino and Wright 1995) and two case reports(Stephens 1995; Miller 2000).

Vicenzino and Wright (1995) utilized a singlesubject ABC design to investigate the effect ofMWM on the pain and impairments of LE. In theirstudy pain and function were assessed by visualanalogue scale for pain, visual analogue scale forfunction, pressure algometry, pain-free grip strengthon a dynamometer, and a pain-free function ques-tionnaire. The authors found that four treatmentsessions of MWM, taping techniques to replicateMWM, and instructing the subject in self-MWM,improved all measures of pain and function. Pain-freegrip, in particular, improved dramatically from thepre-treatment assessment phase (A) to the end ofthe six-week post-treatment assessment phase (C)(Vicenzino and Wright 1995).

Stephens (1995) retrospectively reported a patientcase in which MWM for LE was a part of thetreatment plan. Other interventions included MWMat the wrist, taping techniques, utilization of thermalmodalities, ultrasonic therapy, transverse frictionmassage, exercise, massage, and self-stretches. Whileimprovement was reported for this complex presenta-tion, few objective measures were reported. Miller’s(2000) case report describes the use of the MWM forLE as the primary modality for the correction of

Manual Therapy (2001) 6(3), 163–169

what Miller diagnoses as a ‘positional fault of theelbow joint complex mimicking a contractile elementpathology of the common extensor bundle’ (Miller2000). Full function and absence of pain werereported at a one month follow-up, following thesuccessful two week course of therapy (Miller 2000).

Treatment interventions for LE lack scientificvalidation (Labelle 1992; Stratford et al. 1993; Wright& Vicenzino 1997). No therapy reported to date hasstrong evidential support, therefore novel therapiesare worthy of consideration. Lack of supportingevidence for existing therapies may, however, be dueto methodological deficiencies in the research re-ported to date, including insufficient subject numbersand inappropriate or invalid measures of change(Stratford et al. 1993). Grip dynamometry is anestablished outcome measure in research studies ofLE interventions (Burton 1984; Thurtle et al. 1984;Stratford et al. 1987; Wadsworth et al. 1989; Vicen-zino & Wright 1995; Pienemaki et al. 1996; Wuori1998). Stratford et al. state that maximum gripstrength and visual analogue scale pain reports arethe measures most commonly utilized in the literature(Stratford et al. 1987; Stratford et al. 1993). Stratfordet al. (1993) found that maximum grip strengthdemonstrated the greatest responsiveness to changefollowing an intervention, but that it had poorvalidity as a measurement of outcome-over-time forthe assessment of clinically important change, in aclinical trial of LE interventions. Pain-free gripstrength was stated to be the most valid physicalmeasure of clinically meaningful change over time inpatients with LE, but it was found to be lessresponsive to change than maximum grip strength(Stratford et al. 1993). Dynamometric measurementof grip strength is highly reliable (Bohannon 1999;Nitschke et al. 1999), although Stratford et al. (1993)report that the reliability coefficient for measurementof pain-free grip strength by dynamometer (0.87) wassuperior to that of maximum grip strength (0.60). Inthis study, both pain-free grip and maximum gripstrength were utilized to assess the immediate effectsof MWM in a symptomatic population, to allowcomparison of the outcome measures.

Specific aims of this study were:

1. To establish what proportion of patients with LErespond favourably to MWM, as indicated by thepatients’ ability to perform a previously painfulactive motion pain-free, during the application ofthe MWM.

2. To establish whether the pain-free grip strength ormaximum grip strength of the affected extremitychanged following the application of one sessionof MWM.

3. To compare the responsiveness of pain-free gripstrength and maximum grip strength, and report

# 2001 Harcourt Publishers Ltd

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Fig. 1—Mobilization with movement (MWM) for tennis elbow.white arrow=direction of force to medial proximal forearm,X=stabilisation of humerus, curved arrow=example of movementperformed by subject (making a fist with concurrent wristextension).

Table 1 Effective direction of MWM* (group one, n=23)

Direction of MWM Frequency

Directly lateral 9*58 posterior of lateral 10*58 anterior of lateral 3*58 caudal of lateral 1

*MWM=Mobilization with Movement for tennis elbow, asdescribed by Mulligan (1995)

Effects of elbow mobilization with movement technique on grip strength 165

the effect size of these measures, in subjects withLE.

METHODS

Subjects

A convenience sample of subjects was solicited fromlocal orthopaedic surgeons and physical therapists,and from the medical department of a major ship-building site. Inclusion criteria included any personwho, at the time of testing, experienced lateral elbowpain with gripping activities, or resisted wrist orfinger extension. Exclusion criteria included personswho had a) bilateral lateral epicondylalgia; b) surgeryfor lateral epicondylitis within the last twelve months;c) history of fracture of either radius or ulna that theyknew to limit ROM; or d) history of rheumatoiddisease, or neurologic impairment including stroke orhead injury.

Materials

A grip dynamometer (Jamar, Clifton, NJ, USA) wasused for grip strength measurements.

Procedure

The research protocol is summarized as follows:

1. Subjects signed a consent form to participate inthe study, and filled out a brief questionnaire

2. Subjects were instructed to lie supine on atreatment table. The primary investigator (PI)established with the patient what active motionreproduced the patient’s elbow pain; this wasconsidered to be the ‘comparable sign’. Thecomparable sign was one of the following:making a fist, gripping a rolled elastic bandageof 5 cm diameter, wrist extension unresisted, wristextension resisted by rubber tubing (Theratube,Theraband Corporation, USA), third fingerextension unresisted, or third finger extensionresisted. The first of the above motions to bereported as painful was designated the comparablesign, and no further motions were assessed

3. By random assignment, either the left or right armwas designated to be tested first

4. Dynamometric measurement of pain-free gripstrength, and then maximum grip strength wasperformed with the arm at approximately 308 ofabduction, with the elbow rested on the treatmenttable and the wrist rested on rolled towel 8 cm indiameter. The forearm was in neutral pronation/supination. The PI was unable to see the face ofthe dynamometer, which was read and recorded

# 2001 Harcourt Publishers Ltd

by a research assistant. Both limbs were tested inthe order dictated by random assignment;

5. The PI then performed the MWM, consistingof a laterally-directed manual pressure to theproximal medial forearm (Fig. 1) while the subjectperformed the comparable sign motion (Mulligan1995). Based on the suggestion of Mulligan (1995),up to four attempts were allowed to find thedirection of the manual pressure that eliminatedthe comparable sign on the affected side. The fourdirectional options were standardized andrecorded on the data form (see Table 1). At thistime, if pain with the comparable sign waseliminated (positive response to MWM) thesubject was allocated to group one; if pain withthe comparable sign was not eliminated (negativeresponse to MWM) the subject was allocated togroup two. Differential grouping of subjects whorespond negatively to the MWM trial is consistentwith established principles of clinical decision-making in the application of all mobilizationswith movement (Mulligan 1993, Mulligan 1995,Vicenzino & Wright 1995).

Based on the suggestion of Mulligan (1995), thepatient performed the previously painful motionup to ten times while the MWM was beingapplied. If the pain returned prior to achievingten movements, no further repetitions wereperformed. The number of repetitions was

Manual Therapy (2001) 6(3), 163–169

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Table 2 Maximum and Pain-free grip strength measurements*

Grip StrengthMeasured(n=23)

Pre-interventionmean (SD)

Post-interventionmean (SD)

Differencebetweenmeans ofpairs

Pain-free grip(unaffected limb)

90.0 (27.9) 87.3 (25.9) 72.7 (NS)

Pain-free grip(affected limb)

51.6 (27.2) 62.0 (25.0) 10.4{

. Differencebetweenmeans of pairs

38.4{ 25.3{ —

Maximum grip(unaffected limb)

95.1 (27.8) 95.8 (29.0) 0.7 (NS)

Maximum grip(affected limb)

81.8 (35.0) 85.9 (32.6) 4.1¥

. Difference be-tween means ofpairs

13.2{ 9.9} —

*Measured by a grip dynamometer in pounds of force.SD=standard deviation from the mean.NS=Not significant.{Significant difference P�0.001.{Significant difference P�0.005.} Significant difference P�0.025.¥Significant difference P�0.05.

166 Manual Therapy

recorded on the data form by the researchassistant. When the unaffected limb was tested,the procedure remained unchanged. Having nosymptoms on the unaffected side, the subject wasinstructed to perform the same motion on theunaffected side as had been established as beingthe comparable sign on the affected side;

6. The limb tested first was re-measured for pain-freegrip strength, and then maximum grip strength;

7. The limb that remained untested, according torandom assignment, then received the MWMintervention and was subsequently re-measuredfor grip strength. The total time per subject wasapproximately 15minutes.

This research study was approved by the Institu-tional Review Board of the University of St.Augustine for Health Sciences, as being in compli-ance with the Protection of Human Subjects Regula-tions, the guidelines of the 1975 Helsinki declaration,and the American Physical Therapy Association(APTA) code of ethics.

Data Analysis

The statistical package used for data analysis wasSPSS 9.0 (SPSS Inc., Chicago, Ill.). The a priori levelof significance was set at a=0.05.

The grip dynamometry data are matched samples(pre – post, or affected – unaffected). The one-tailedt-test was used to compare group means, as clinicalobservations indicated a unidirectional effect of theintervention on the dependent variables.

RESULTS

Properties of the Sample

Thirty-two subjects were referred for this study. Foursubjects were ineligible (two with bilateral epicondy-lalgia, one with medial epicondylalgia, one without acomparable sign). Two subjects declined to partici-pate in the study, and one potential subject wasunable to be contacted. Of the eligible subjects (25),seventeen (68%) were males. The average age ofsubjects was 46 years (range, 29–60). Eighteen (72%)were employed at industry or heavy industry, three(12%) performed clerical or data input work, three(12%) were involved in the teaching or delivery ofhealth-care, and one did not claim an occupation.Two subjects had LE of less than one monthduration. The remaining (23) subjects had chronicLE (average 16 months, range 2 months to 8 years).

Hand dominance was determined by which armthe subjects reported they would use to throw a ball.Eighteen subjects were right-hand dominant. Sevenwere left-hand dominant. Twelve reported LE of theright elbow, thirteen reported left-sided LE. The

Manual Therapy (2001) 6(3), 163–169

dominant arm was affected in fifteen (60%) of thesubjects.

Response to MWM

Of the 25 eligible subjects, 23 (92%) respondedpositively to MWM assessment (i.e. were able toperform a previously painful active motion pain-free,during the application of the MWM), and so wereplaced in group one. The number of times that eachpossible direction of force for MWM was used isreported in Table 1. Twenty-two of the 23 subjectswere able to perform ten repetitions of the compar-able sign movement pain-free, while the MWM wasapplied. The one remaining subject experienced areturn of pain on the eighth repetition, at which pointintervention was ceased.

Normality of distribution of data

Appropriate use of the t-test requires that the datafall within the typical normal distribution. Analysisby the w2 test confirmed that the data from groupone (n=23) were not significantly different to thedistribution defined by the normal curve. The t-testwas, therefore, used to obtain the following resultsfor group one. The data from group two (n=2) willbe addressed separately.

Grip strength dynamometry

Pre-intervention and post-intervention dynamometricgrip strength data are provided in Table 2. Data fromgroup one only were included in the analysis.

# 2001 Harcourt Publishers Ltd

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Effects of elbow mobilization with movement technique on grip strength 167

The affected limb was significantly weaker in bothpain-free grip and maximum grip strength, comparedto the unaffected limb (Table 2). This differencepersisted, to a lesser degree, post-intervention(Table 2).

Both pain-free grip strength and maximum gripstrength increased significantly from the pre-inter-vention to post-intervention on the affected side(Table 2).

No significant differences were seen between thepre-intervention and post-intervention measures foreither pain-free grip strength or maximum gripstrength on the unaffected side.

Due to the small number of subjects in group two(those who did not respond favourably to MWM),statistical analyses were not possible. In these twocases maximum grip strength of the affected limbdecreased post-intervention, by an average of 23%(15 lb.). Pain-free grip strength for the subjects ingroup two changed by 5 lb. or less (range 0–5 lb.) inall instances, and was therefore not considered to beclinically significant.

DISCUSSION

The results of this study indicate that the MulliganMWM is a useful technique for eliminating thepain of a previously painful active movement, inpatients with lateral epicondylalgia. Ninety-twopercent of subjects in this sample were able toperform a previously painful motion pain-free,during the application of the MWM. Theseresults indicate that MWM may be a usefulintervention modality in the rehabilitation of patientswith LE.

MWM resulted in a significant increase in bothpain-free grip strength and maximum grip strengthfrom pre-intervention to post-intervention for theaffected limb (Table 2). While pain-free grip increasedby almost 17%, which we consider to be clinicallysignificant, the magnitude of change for maximumgrip strength was less than five percent, which we donot consider to be clinically significant. The observa-tion that the average percent magnitude of change inpain-free grip strength was more that three times thatof maximum grip strength are in contrast to theresults of Stratford et al. (1993). In their studymaximum grip strength was found to be moreresponsive to change than pain-free grip strength,based on a greater mean magnitude of change,combined with a greater homogeneity of change(represented by a lower standard deviation from themean). In our sample, pain-free grip strengthdemonstrated the greater magnitude of change, andthe greatest homogeneity of change, on the affectedlimb (Table 2). These results suggest that pain-freegrip strength is the more responsive measure.

# 2001 Harcourt Publishers Ltd

Additionally, Stratford et al. (1993) found thatpain-free grip strength was a more valid measure ofclinically important change over time than maximumgrip strength. These facts are important in the designof further research into the efficacy of interventionsfor patients with LE.

An important issue in research design is determin-ing an adequate sample size. To do this, theresearcher performs a power analysis, which requiresan estimate of the magnitude of effect the proposedintervention may have on the measured dependentvariable (called the effect size index). To assist futureresearchers in performing a power analysis, we usedthe data from our study to calculate the effect sizeindex (d) for the dependent variables of pain-free gripstrength and maximum grip strength. The results(adjusted for paired data) show that pain-free gripstrength (d=0.861) had a greater effect size thanmaximum grip strength (d=0.585), meaning that astudy using pain-free grip strength as a dependentvariable will not need as many subjects as a study thatuses maximum grip strength in order to demonstratethat an actual change has occurred.

The one-group pretest – post-test design is anuncontrolled, quasi-experimental design, and there-fore susceptible to threats to internal validity(Portney & Watkins, 1993). Temporal effects, suchas maturation and history effect, are a particularthreat to an uncontrolled design such as this. In thiscase, however, there was minimal time betweenpretest and post-test (a few minutes), therefore wefeel it is unlikely that the changes in grip strengthfound are the result of a temporal factor. Testingeffects are also a threat to an uncontrolled experi-ment. In the case of a painful condition, however, adecrease in grip strength with repeated testing wouldseem the more likely effect, and therefore we feel thatthis effect is unlikely to explain the outcome of thisstudy. In situations where extraneous variables suchas temporal and testing effects are effectively con-trolled, the one-group pretest – post-test design isreasonable (Portney & Watkins, 1993). Externalvalidity may have been affected by inadvertent biasdue to our use of the purposive method of sampleselection. Another limitation of our study is that onlythe immediate effects of MWM were measured, withno attempt made to determine whether the absence ofpain with the comparable sign movement, or thechanges in grip strength, were maintained over time.Therefore these results are not generalizable tooutcomes of an episode of care, only to a singletreatment session. Mulligan’s clinical experience(Mulligan 1995; 1999), case reports (Stephens 1995;Miller 2000), and a single case study (Vicenzino andWright 1995) indicate the usefulness of this MWMfor the rehabilitation of patients with LE. Furtherresearch to establish the efficacy of MWM overcomplete episodes of care, and long-term follow-up,

Manual Therapy (2001) 6(3), 163–169

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168 Manual Therapy

for patients with LE should use pain-free gripstrength as an outcome measure in preference tomaximum grip strength. Our results indicate that asample size of twenty-five subjects was sufficient todemonstrate statistical significance of all measures ofgrip strength which met our criterion for clinicalsignificance, however we would expect that over alonger trial, more subjects would drop out or fail torespond to the intervention, necessitating a largersample. Other outcome measures utilized may possesssmaller effect sizes, and therefore would necessitatelarger sample sizes. Stratford et al. (1993), for ex-ample, recommend a pain-free function questionnaireas a valid measure, (i.e. a measure that correlatessignificantly with the patient’s global impression ofchange over time). Based on their calculation of effectsize, Stratford et al. (1993) conclude that a samplesize of sixty-three subjects would be necessary tostatistically demonstrate change, where changeexists and within standard probabilities of error,using their pain-free function questionnaire as anoutcome measure.

CONCLUSION

The Mulligan MWM technique for tennis elbow(Mulligan 1995; 1999) was effective in allowing apreviously painful active movement to be performedpain-free, while the mobilization was being applied,in ninety-two percent of subjects with lateral epicon-dylalgia in this study. Measures of pain-free gripstrength and maximum grip strength improvedsignificantly immediately following the MWM inter-vention. These initial results indicate that randomizedcontrolled clinical trials should be undertaken toinvestigate the long-term efficacy of a treatmentprotocol utilizing the Mulligan MWM technique fortennis elbow. We recommend that future studiesintending to differentiate patients who undergoclinically important functional changes, from patientswho do not, should utilize pain-free grip strength as adependent variable in preference to maximum gripstrength.

Acknowledgements

The authors wish to thank Drs Albert Volk, James Grimes, ArnoldGraham-Smith, and Maria Mazorra, as well as John Bendt,Matthew Jeffs, Jenna Geiger, and Leigh-Ann Tabor for theirassistance in obtaining volunteer subjects for this research. Thanksalso to Corlia van Rooyen for her valuable assistance with datacollection, and to the staff of the medical department of Bath IronWorks, particularly Darren Beilstein, Paul Hempstead, JoannaStreeter, and Wayne McFarland for their cheerful and extremelyvaluable assistance. Thanks also to Drs Susan Mercer and DarrenRivett for critical review of previous versions of this manuscript.Mr Abbott wishes to express his sincere appreciation to hisresearch advisors; thank you Drs Catherine Patla, Richard Jensenand Deborah Jackson. This paper is dedicated to the memoryof the primary advisor for this research, the late Dr. William

Manual Therapy (2001) 6(3), 163–169

A. Saville, who passed away suddenly before completion of theproject.

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