McConnell Taping Shifts the Patella Inferiorly in Patients With Patellofemoral Pain: A Dynamic Magnetic Resonance Imaging Study

Introduction

Patellofemoral pain syndrome (PFPS) is one of the most commoncauses of orthopedic-related physician visits each year, especiallyamong women.^1,2 Patellofemoral pain syndrome can be caused bydirect trauma to the knee, or the cause can be insidious innature. Altered lower-extremity biomechanics, such as poor hiprotation control,³ excessive foot pronation,⁴ femoral anteversion,tibial torsion, bone configuration, or tight muscles are thoughtto contribute to PFPS by initiating alterations in patellofemoralkinematics.^5,6 Vastus medialis oblique muscle dysfunction alsohas been proposed as a contributor to altered patellofemoralkinematics.^7–10 Interventions for PFPS include patellartaping, patellar bracing, selective strengthening of the vastusmedalis muscle, iliotibial band stretching, ankle-foot orthotics,or a combination of these interventions.^11–15

Patellar taping is widely practiced among clinicians to treatpatients with PFPS. This intervention involves pushing the patellamedially and securing it in this position with tape on the skin.Originally, the McConnell taping technique was developed tocorrect altered patellofemoral kinematics and permit participationin normal daily activity.¹⁶ Today, there exist several variationsof McConnell taping techniques, where attempts are made to alterpatellar tilt, glide, or rotation.¹⁷ Clinical application ofthese techniques is based on a physical examination of patellarposition, orientation, and mobility.^18,19 The underlying conceptis that most patients with PFPS would benefit from medializationof the patella, which theoretically would off-load the compressiveforces at the lateral patellofemoral joint.^16,20

Although patellar taping has been demonstrated to reduce patellofemoralpain in patients with PFPS,^21–26 the kinematic sourceof this pain reduction has not been identified. Likely, thisfailure to identify the kinematic source of the pain reductionis due to the fact that the complete 6 degrees of freedom patellofemoralkinematics (post-taping) during active extension has not beenquantified in a group of patients with PFPS. Instead, patellofemoralaxial alignment changes (patellar translation and tilt) dueto taping in patients with PFPS have been quantified in a smallnumber of studies.^21,27–30 The majority of studies focusedon static evaluation of knee posture without muscle activity.Isometric quadriceps muscle activity has been incorporated intoa few of these studies.^21,28 In these studies, no differencesin lateral patellar translation or tilt were found with taping,with or without muscle contraction.

Thus, the purpose of this study was to quantify the changesin the 6-degrees-of-freedom patellofemoral kinematics due toMcConnell taping in people with PFPS during dynamic knee flexionand extension using fast-phase contrast (PC) magnetic resonanceimaging (MRI). In doing so, 2 null hypotheses were tested: (1)McConnell taping does not alter the patellofemoral kinematicsin all 6 degrees of freedom, and (2) no correlations exist betweenthe baseline patellofemoral kinematics (untaped condition) andthe change in kinematics due to taping.

Method

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Method

Participants

Fourteen volunteers diagnosed with PFPS gave informed consentprior to participating in this study. Participants were recruitedfrom local orthopedic clinics and ongoing National Institutesof Health studies. This recruitment was primarily Web-based(http://clinicalresearch.nih.gov), conducted through the ClinicalCenter Patient Recruitment and Public Liaison Office. Participantswere excluded if they had any contraindications to having anMRI scan. Both knees were evaluated in the initial screeningexamination. To be included in the study, each knee had to beclinically diagnosed with PFPS, with symptoms present for ayear or longer. An in-house physiatrist, using both a physicalexamination and the patient's history, excluded any knee thathad: (1) previous surgery (including arthroscopy); (2) ligament,meniscus, iliotibial band, or cartilage damage; (3) other lower-legpathology or injury; or (4) traumatic onset of PFPS.

In addition, a physical therapist (T.J.B.) examined each kneefor evidence of altered patellofemoral kinematics: (1) Q-angleof $≥$ 15 degrees,^18,31,32 (2) a positive apprehension test, (3)patellar lateral hypermobility of $≥$ 10 mm,¹⁸ or (4) a positiveJ-sign.^18,32,33 Any knee that did not exhibit 1 or more of these4 signs was excluded. These measures were used solely as inclusionand exclusion criteria and were not included in the kinematicdata analysis arm of the study. Both the Q-angle and lateralhypermobility were measured with the participants in a supineposition with the knee in full extension and muscles relaxed.In this position, patellar lateral hypermobility was definedas the ability of the examiner to move the patella laterallyby 10 mm or more. To confirm or deny the presence of a J-sign,participants were seated at the end of the table and the examinerevaluated patellar motion as the participants raised their leginto full extension. The pain in each knee was evaluated usinga visual analog scale (VAS) pain score and a Kujula score.³⁰In total, 19 knees from 14 participants were included in thisstudy (Tab. 1).

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Table 1. Demographics and Clinical Intake Parameters^{^a}

Procedure

Each knee underwent 2 testing conditions in the MRI (untapedand taped), which were randomly ordered. For each condition,participants were placed supine in a 1.5-Tesla magnetic resonanceimager (CV-9.1M4 or LX-9.1M4).^*^,³² After acquiring a set ofstatic alignment scans, the participants were allowed to practicethe extension-flexion exercise until they could repeatedly extendand flex their knee to and from maximum attainable flexion andfull extension at 35 cycles per minute to the beat of an auditorymetronome. Participants were instructed to generate knee extensionwithout hip movement, and a loose strap was placed over thethighs as a reminder, but minor femoral motion was allowed toenable a natural movement. Next, a full fast-PC MRI image set(x,y,z velocity and anatomic images over 24 time frames) wasacquired while the participants volitionally extended and flexedtheir knee to the beat of the auditory metronome, as practiced.In addition, fastcard images (anatomic only) were acquired in3 axial planes during the cyclic movement. An in-house musculoskeletalradiologist reviewed all magnetic resonance images to rule outligament, meniscus, iliotibial band, or cartilage damage.

During tape application, participants were positioned supinewith their quadriceps muscle relaxed. They were taped by a physicaltherapist (T.J.B.) with more than 15 years of experience inorthopedics and sports medicine. Initially, Hypafix was appliedto the skin covering the knee. Next, a medial glide of the patellawas obtained by manually pushing the patella medially to itsend range of motion. Rigid strapping tape then was used to maintainthe medial glide of the patella by pulling the skin and patellamedially. Participants were required to walk for 5 minutes ata self-selected, comfortable pace after taping and prior tothe MRI experiment.^27,29

Three-dimensional rigid-body rotations and displacements ofthe femur, tibia, and patella were quantified through integrationof the fast-PC velocity data. It is important to note that althoughthe fast-PC acquisition was based on a single imaging plane,the 3-dimensional velocity data allowed the orientation anddisplacement of all bones to be accurately tracked 3-dimensionallythroughout the movement.³⁴ Kinematics were defined based onan anatomical coordinate system. Unlike earlier cine MRI experiments,^35,36 this identification was completed for a single time frameonly, and the fast-PC data were used to track the bones’kinematics through all time frames. Thus, the need to visuallyidentify anatomical landmarks at multiple time points^35,36 waseliminated, which minimized errors due to inconsistency in imageplane location and orientation^37,38 and provided excellent accuracy(<0.5 mm³⁹) and precision (<1.16°⁴⁰). The kinematicsof the patella relative to the femur were defined using 6 variables:3 displacements—lateral-medial (LM), inferior-superior(IS), and posterior-anterior (PA)—and 3 rotations—lateral-medialtilt (LM tilt), extension-flexion (EF), valgus-varus rotation(VV). A significant increase in the superior position of thepatellar origin relative to the femoral origin was defined aspatella alta. From the patellar-tibial kinematic data, patellartendon length was calculated as in a previous study.⁴¹ All datawere presented for the extension portion of the movement only.Due to individual variations in range of motion within the magneticresonance scanner, not all participants were represented atthe extreme ranges of knee flexion and extension. Thus, theaverage data presented were limited to the central range ofmotion, where 3 or more participants were represented by theaverage.

The kinematic data were reduced to the magnitudes of each ofthe 6 kinematic variables when the knee was at 10 degrees ofknee extension (defined as the "value" of that variable). Theuntaped condition was considered baseline. A 10-degree kneeflexion angle was used because not all participants were ableto achieve full knee extension (0° flexion angle). In addition,patellar taping should have the greatest effect when the patellais in terminal extension and is most free from the constraintsof the femoral groove.^5,35,42

Data Analysis

Statistical differences between the taped and untaped conditionswere investigated using a paired 2-tailed Student t test. Correlationsbetween the baseline patellofemoral kinematics and the changein kinematics due to taping were quantified. Minimal correlationsbetween pain scores (VAS and Kujula) and patellofemoral kinematicshave been documented (only the slope of patellofemoral varusrelative to knee extension correlated with VAS pain score) inpatients with PFPS.⁵ Because the current population was a subsetof this earlier study, these correlations were not performedin the current study. Statistical significance was set at P $≤$ .05,(SPSS, version 14.0). An a priori sample size calculation determinedthat adequate power ( ${alpha}$ =.05, β $≥$ .80) could be achieved withthe inclusion of 15 knees, assuming that taping would resultin a 2-mm medial patellar shift³⁰ and that the standard deviationassociated with this change would be 2.5 mm.³⁴

Results

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Results

The null hypothesis that McConnell taping does not alter thepatellofemoral kinematics was rejected for a single variableonly: IS displacement (Fig. 1, –1.6 mm, P=.04). The onlysignificant effect of patellar taping was an inferior (downward)shift in the patella. This inferior shift resulted in an insignificantdecrease in the patellar tendon length at 10 degrees of kneeextension ( ${Delta}$ length =–0.46, P=.79). However, there weresignificant differences in kinematics between the participantswith PFPS included in the current study and a previous sampleof individuals who were asymptomatic.³⁴ On average, the participantswith patellofemoral pain were 2.1 mm (P=.04), 4.2 mm (P=.03),and 2.3 mm (P=.05) more laterally, superiorly, and anteriorlydisplaced than the control population. In addition, these participantswere 5.3 (P<.001) and 2.5 (P<.001) degrees more flexedand rotated into valgus than the control population (Tab. 2).

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Figure 1. Patellofemoral kinematics in the untaped and taped conditions: Each variable is plotted relative to knee extension, with full extension being equal to zero (participant movement is read from left to right). Data were interpolated to 1-degree knee angle increments, but symbols are provided at every 5 degrees for clarity. One standard deviation bars are provided. The dotted line represents a knee extension angle of 8 degrees. The top row contains displacements (medial, superior, and anterior are the positive directions, respectively), and the bottom row contains the rotations (flexion, medial tilt, and varus rotation are the positive directions, respectively). ${Delta}$ disp=changed in displacement.

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Table 2. Patellofemoral Kinematic Parameters^{^a}

The second null hypothesis that no correlations exist betweenthe baseline patellofemoral kinematics and the change in kinematicsdue to taping was rejected for 3 variables (Tab. 3 and Fig. 2). The strongest inverse correlation existed for LM displacement(r=–.67), and moderate inverse correlations existed forLM tilt and VV (r=–.52 for both). The correlations indicatethat participants with larger absolute baseline kinematic values(further from the asymptomatic average³⁴) would see the greatestabsolute change with taping. Interestingly, not all of the participantswith patellofemoral pain had baseline values of LM displacement,LM tilt, and VV that were lateral and valgus, relative to apreviously defined asymptomatic average.³⁴ Thus, participantswho began with medial displacement, medial tilt, or varus rotation,relative to the asymptomatic population, demonstrated a lateralshift in displacement, lateral tilt, or valgus rotation, respectively,after taping was applied. The participant with the largest valuesof lateral tilt and displacement proved to be an outlier inthat taping caused a much smaller change in these variablesthan the correlation would suggest. Data for this participantwere not removed from the analyses, but when these data areremoved, the correlation between baseline and change with tapingincreases (r=–.54, P=.02) for LM tilt and the correlationsfor LM displacement and VV rotation increase minimally.

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Table 3. Correlations Between the Baseline Patellofemoral Kinematics (Untaped Condition) and the Change in Kinematics Due to Taping

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Figure 2. Change in kinematics with taping (taped and untaped conditions) versus baseline. The 3 variables with significant correlations between the change with taping and the baseline value are shown (top row: lateral to medial displacement and lateral to medial tilt; bottom row: valgus to varus rotation and legend to symbols). The x-axis indicates the untaped value of each variable (positive values indicate medial displacement, medial tilt, and varus rotation). The y-axis indicates the change in each variable with taping (positive values indicate medial displacement, medial tilt, and varus rotation with taping, shown by gray shading). The regression lines are shown for each variable set using a thick black line. Based on previous work,³⁴ the average value for an asymptomatic cohort (untaped, n=34) for each of the 3 variables is shown using a vertical dashed line (medial displacement=–0.11 mm, medial tilt=14.7, varus rotation=0.52°). All graphs represent kinematics at 10 degrees of knee extension. Participants who were laterally translated, laterally tilted, and in valgus rotation (relative to the asymptomatic population) are shown in blue. This distinction is independent for each graph. Thus, a single participant who demonstrated medial displacement and lateral tilt at baseline would be designated by 2 different colors in each of the respective graphs.

Discussion

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Discussion

This study was the first to quantify changes caused by McConnelltaping in the complete 6-degrees-of-freedom patellofemoral kinematicsduring volitional knee extension in a sample of patients withPFPS. On average, the only consistent influence McConnell tapingprovided on patellar kinematics was to shift the patella inferiorly.The benefit of inferiorly shifting the patella within the femoralgroove was an increase in the patellofemoral contact area. Ina previous study, Ward and colleagues⁴³ defined a 19.3% decreasein cartilage contact area in a group of participants with a24% increase in the Insall ratio (superior displaced relativeto a control population). In the current study, the patellaein the participants with PFPS were 24% (5.2 mm) more superiorlyplaced (dynamically) compared with those of the asymptomaticpopulation.³⁴ The inferior shift in displacement with taping(1.6 mm) represents 34.8% of the difference in IS displacementbetween the participants with PFPS and the asymptomatic controls(Tab. 2, 4.6 mm). Increased contact area decreases contact stressat the patellofemoral joint by spreading out the load over awider area. Ultimately, this decrease in contact stress mayaccount for some of the previously reported decrease in patellofemoralpain after taping.^21–26

The correlation between the baseline patellofemoral kinematicsand the change in kinematics due to taping supports earlierwork that identified the existence of subgroups within the patellofemoralpain population.³³ The expected medial change in patellar displacementor tilt occurred in participants with lateral baseline valuesof these variables. Conversely, participants with medial displacementor tilt at baseline demonstrated a lateral change in displacementor tilt with taping. The same relationship held true for VVrotation. Therefore, taping shifts the patella medially in patientswith lateral baseline values of patellofemoral displacement(relative to an asymptomatic average), and it shifts the patellain the opposite direction in patients with medial baseline valuesof patellofemoral displacement. Similarly, taping is effectivein medially tilting the patella in patients with PFPS and lateralbaseline tilt, but it has the opposite effect for patients withmedial baseline tilt. However, average differences in patellarkinematics after taping across all participants produced nosignificant change due to the contrary effect of patellar tapingacross participants. Thus, considering the participants in thisstudy as a single population masked the true changes with tapingseen on a person-by-person basis. Regardless, pain relief mayhave been further enhanced by the centralization of the patellain regard to patellar LM displacement, LM tilt, and VV rotation.

One interesting exception in this study was a single participantwho had the largest lateral displacement at baseline (–14.5mm), yet demonstrated minimal medialization with taping. Thisparticipant had the highest baseline values of superior displacement(39.0 mm, asymptomatic average [±SD]=21.7±6.3mm). If the inferior shift in patellar placement is consideredthe primary effect of taping, then the lack of kinematic changefor this specific participant may have been due to patella alta.In general, for most patients with PFPS with lateral baselinevalues of patellofemoral LM displacement, the inferior shiftand taping may lead to further patellar engagement with thefemoral sulcus. Thus, both the force of the taping and the boneconstraint may have medialized the patella placement. This conceptis supported by a previous study that demonstrated a strongcorrelation between patellofemoral superior and lateral displacement.⁵ Yet, for this participant, the small inferior shift may nothave resulted in patellar engagement with the sulcus, and tapingalone was insufficient to cause a large medialization force.

It is counterintuitive that a medial taping technique couldcause lateralization of the patella in patients with PFPS. Yet,patients who begin with medial baseline values for LM displacementdo not demonstrate patella alta.³³ In the absence of patellaalta, it is likely that the patella remained partially engagedwith the femoral sulcus throughout extension, enabling the patellato remain medially placed. When the patella was inferiorly displacedwith taping, the patella was further engaged with the sulcus.The bony constraints of the sulcus, due to either the shapeof the groove or limb alignment, resulted in the patella shiftinglaterally relative to the femur, and taping could not overcomethis bone force. The fact that any patient with PFPS had medialpatellar placement relative to the femur may appear contraryto the fact that the clinical markers used as inclusion criteriashould have confirmed the presence of excessive lateral tracking.This potential incongruity is explained by a recently publishedfinding that the value of Q-angle is correlated with medialand not lateral patellofemoral displacement.³³

The current results support and expand the findings of previousstudies on the effectiveness of McConnell taping. Typically,previous taping studies focused on a static, 2-dimensional evaluationof patellar alignment with or without muscle contraction.^21,27–30 On average, taping was shown to be ineffective inshifting and tilting the patella medially. Taping has been shownto be effective if it was evaluated prior to any exercise, buta short bout of exercise eliminated this effect.^24,29 The currentstudy design included a short bout of exercise prior to evaluatingthe taping condition, but our study differed from past studiesin its 3-dimensional dynamic evaluation of a volitional task.Based on this experimental design, McConnell taping was shownto be effective in shifting the patella inferiorly after a shortbout of exercise. We also demonstrated that taping tended toshift patellar LM displacement, LM tilt, and VV rotation backtoward the asymptomatic average. Thus, it is likely that theineffectiveness of taping found in previous studies was dueto the fact that some patients were not laterally tilted ordisplaced prior to taping.

Although the current study used dynamic movement, which is representativeof how muscle action can influence patellar kinematics, therewere limitations. The movements were isolated to the knee, neglectingthe influence of proximal or distal joints on patellofemoralkinematics. The range of motion was limited, but did cover fromjust prior to and through terminal extension, where alteredpatellofemoral kinematic patterns are most evident. The experimentaldesign did not include an axial compressive load applied tothe leg; thus, it is not known how such loading could affectpatellar kinematics and taping. Another potential limitationof this study was the fact that the exact force applied withtaping was not quantified. Yet, in previous studies, participantsoften applied their own tape,^21,44 and no previous study measuredthe force applied with taping.^{17,21,24,29,30,44,45} Lastly, painwas not measured after tape application. This measure was notincluded in the study design, as previous studies^21–26have clearly shown the effectiveness of taping for pain reduction.Thus, the current study was focused specifically on accuratelyquantifying how taping alters 3-dimensional patellofemoral kinematicsby measuring them noninvasively and in vivo during volitionalactivity. The noninvasive nature of this experiment and itshigh accuracy, excellent precision, and ability to demonstrate3-dimensional kinematic differences during volitional activitiesjustify these limitations.

Conclusions and Clinical Relevance

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Conclusions and Clinical...

This is the first study to evaluate 3-dimensional changes inpatellar kinematics with McConnell taping during voluntary activemotion. For the participants in this study, patellar tapingshifted the patella inferiorly with respect to the femur, whichmay account for some of the previously reported pain reliefwith taping, due to an increase in contact area. McConnell tapingmedialized the patella in participants who demonstrated lateraldisplacement at baseline and lateralized the patella in participantswho demonstrated medial patellar displacement at baseline. Thus,medialization of the patella with taping was dependent uponthe patellofemoral kinematic alterations present in each participant.This finding reinforces the need to clinically identify thespecific alterations in patellofemoral kinematics present ineach patient so that specific interventions can be used andoptimized to correct these altered kinematics and reduce pain.All patients with PFPS and altered patellofemoral kinematicsare likely to benefit from an inferior shift of the patella,which should reduce patellofemoral contact stress.

Footnotes

Ms Derasari, Dr Alter, and Dr Sheehan provided concept/idea/projectdesign, data analysis, and project management. Dr Brindle, DrAlter, and Dr Sheehan provided writing. All authors provideddata collection. Dr Sheehan provided fund procurement. Ms Derasariprovided participants. Dr Brindle provided consultation (includingreview of manuscript before submission).

The authors thank Elizabeth K. Rasch, PT, PhD, for support onthe statistical analysis and Steven Stanhope, PhD, for guidancethroughout the project. They also thank Bonnie Damaska, JamieFraunhaffer, Jere McLucas, Dr Ken Fine, and the Diagnostic RadiologyDepartment at the National Institutes of Health for their supportand research time.

This study was approved by the National Institute of Child Healthand Development.

This research was supported, in part, by the Howard Hughes Foundationand the Intramural Research Program of the National Institutesof Health (Clinical Center and National Institute of Child Healthand Human Development). Any opinions, findings, and conclusionsor recommendations expressed in this material are those of theauthors and do not necessarily reflect the views of the NationalInstitutes of Health or the US Public Health Service.

^* GE Medical Systems, 4855 W Electric Ave, Milwaukee, WI 53219-1628.

Smith & Nephew DonJoy, 2777 Loker Ave, Carlsbad, CA 92010.

SPSS Inc, 233 S Wacker Dr, Chicago, IL 60606.

References

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