Reliability of measurements obtained with four tests for patellofemoral alignment
- 1. Research Report Reliability of Measurements Obtained With Four Tests for Patellofemoral Alignment Background a d Purpose. A series of patellofemoral (PF) alignment tests G Kelley Fitzgemld have been described that are used to determine when and how P taping tech- F Philip W McClure niques should be applied. The reliability of measurements obtained with these tests has not been reported. 7beputpose of this study was to determine the in- tertester reliability of measurements obtained with four P alignment tests: F medial/luteral displacement, mediaUatera1 tilt, medial4ateral rotation, and anterior tilt. Subjects. Twelvephysical therapistsfrom four clinics served as testers. A total of 66patients w e evaluated.Metbods. Paired testersper- formed all four P alignment tests on the same patient. The intertester reliabil- F ity of judgments for each of the P alignment tests was determined by a kappa F correlation coe$icient. Results. Kappa correlation coeficients ranged from .10 to .36for thefour P alignment tests. Conclusion and Discussion These F Jndings suggest that the reliability of measurements obtained with the PF alignment tests described in this report ranged from poor to fair. Potential fac- tors a$ecting the reliability of these measurements are discussed. Alternative method for deciding when and how to apply P taping techniques are also F discussed. [Fitzgerald GK, McClure PW. Reliability of measurements obtained with four testsforpatellofemoral alignment. Phys Ther. 1995;75:84-92.1 Key Words: Patellofemoral joint, Patellofemoral makalignment, Reliability. The tern1 "patellofemoral (PF) mala- interventions have been described for ment, mediaMatera1 tilt, medial/lated lignment" implies that there is a dis- PF rnalalignment, all of which empha- rotation, and anterior tilting of the ruption in the normal tracking of the size reducing factors that may contrib- patella with respect to the femur. The patella in the femoral groove during ute to the malalignment.1-7 results of the tests are used to assist knee moti0n.l This condition may the therapist in m a h g treatment result in abnormal stresses being ap- McConnef14 has described a series of decisions regarding PF taping tech- plied to structures associated with the tests for determining PF alignment. niques and therapeutic exercise proce- PF joint, producing pain and d a m - These tests examine the presence or dures, which are also described by mation. A number of physical therapy absence of mediaylateral displace- McConnell.* The reliabihty of measurements ob- tained with the PF alignment tests GK Fitzgerald, PT, OCS, is Assistant Professor, Department of Phys~calTherapy, Hahnemann Uni- has described by McCo~ell* not been versity, Mailstop 502, Broad and Vine Sts, Philadelphia, PA 19102 (USA). Address all correspon- reported. A preliminary investigation dence t M Fitzgerald. o r performed by the first author (GKF) PW McClure, PT, OCS, is Assistant Professor, Department of Physical Therapy, Hahnemann on 30 subjects, with and without PF University. pain, suggested that intratester reliabil- This study was approved by the Committee for Human Studies, Hahnernann University. ity of these measurements was poor. If the reliability of measurements o b This article is adapted from a platform presentation at the American Physical Therapy Association Combined Sections Meeting; February 5, 1334; New Orleans, LA. tained with this evaluation procedure are poor, clinical decisions that are 7bis article was submitted March 9, 1994, and was accepted ~eptember 1994 8, Physical Therapy /Volume 75, Number 2 / February 1995
- 2. - Table 1. Characterrstics of Testers Clinic Knee Disorders. Case Load (%) Patients Examinedb Therapist No. (Years of Experience)' noses directly related to PF dysfunc- tion (ie, PF pain syndrome, anterior knee pain, chondrornalacia patellae, subluxating patella, patellar tendinitis, patellar fracture). The remaining sub- jects had diagnoses consisting of me- niscal pathology, ligamentous pathol- ogy, and fractures of the femur or tibia. Subjects were excluded from the study if they had received a surgical procedure specifically to realign the patella (eg, lateral retinacular release). All subjects signed an informed con- sent form prior to participation in the study. Testers Testers in this study were 12 physical therapists employed at one of four physical therapy clinics in the PMadel- phia, Pa, area. All testers frequently "Percentage of the therapists' case loads that comprised patients with knee disorders treated patients with knee disorders or ? h e number of patients examined for this study from each clinic. PF joint dysfunction in their practice. The experience (in years) of each therapist treating patients with knee disorders. AU testers used PF taping techniques for treating these patients and were familiar with the PF alignment tests made based on this procedure may Based on the results of the preliminary prior to participation in the study. not be valid. investigation, a broader study includ- Only 1 tester learned the alignment ing more subjects and testers at sev- tests from attending a continuing edu- A number of consequences may result eral clinical facdities was deemed cation course given by McConnell. Al l from selecting treatment for PF dys- necessary to examine reliabhty. The other testers learned the alignment hnction from unreliable measure- purpose of this study was to deter- tests by reading published descriptions ments of PF alignment. For example, if mine the intertester reliability of mea- of the tests4 or from colleagues who PF taping techniques are selected surements taken with four tests for PF learned the tests in other continuing based on unreliable measurements, alignment, as described by McCon- education courses. Table 1 provides the treatment may not be effective. nell.4 We chose to design the study in demographic information of therapists Taping may then be incorrectly dis- a similar fashion to other investigators at each clinic site. missed a an ineffective treatment for a s assessing reliability of clinical patient who may be helped by a dif- assessments.8 Patellofemoral Alignment Tests ferent taping techmque. Unreliable - - measurements of alignment may also Method Because the testers participating in the lead to a false impression about the study learned the PF alignment tests mechanism involved if taping is suc- Subjects from varying sources, we decided to cessful in relieving symptoms. For provide standardized instructions of example, suppose we have concluded Sixty-six subjects 0 male, 35 female) 1 these tests. All testers received a writ- that our patient has an excessive lat- participated in the study. Subject ages ten description and a photograph of eral displacement of the patella based ranged from 14 to 74 years each specilic test of alignment. We on our examination of alignment. I f (R?SDl=29.7+13.1). Mean height chose this method of standardizing the the measurement is unreliable, there is and weight were 171.2210.2 cm instructions because it would allow a chance that perhaps the patella is (67.424.0 in) and 73.4219.6 kg our results to be generalized to thera- not displaced or displaced medially. (161.9?43.1 lb), respectively. AU sub- pists who followed our written instruc- Nevertheless, we would select a taping jects were referred for physical therapy tions and photographs of the tests. We technique for a lateral displacement. If by their physicians. Subjects were elected not to perform personal in- our patient's condition improves, we included in the study if the examining struction or demonstrations of the may assume it was because we re- therapist believed that assessment of tests, because then the results would stored normal PF joint alignment PF alignment would be part of the only be generalizable to therapists when in fact the improvement had typical physical therapy evaluation for who received our personal instruction. nothing to do with joint alignment. that patient. Forty subjects had diag- The following instructions for the 10 / 85 Physical Therapy / Volume 75, Number 2 / February 1995
- 3. Anterior tilt. Anterior tilt is deter- mined by palpating the Inferior pole of the patella (Fig. 3). If no significant anterior tilt exists, the inferior pole should be easily palpated.4 An anterior tilt is present if the examiner must place a downward pressure on the superior pole of the patella so that the inferior pole becomes superficial enough to ~ a l p a t e . ~ Patellar rotation. Patellar rotation is determined by examining the relation- ship between the longitudinal axis of the patella and the longitudinal axis of the femur (Fig. 4). The longitudinal axis of the patella should normally be in line with the anterior superior iliac spine (ASIS). If the distal end of the longitudinal axis of the patella is an- gled lateral to the ASIS, then the pa- tella i considered to be rotated lateral- s l ~ If . ~ distal end of the longitudinal the axis of the patella is angled medial to the ASIS, then the patella is considered to be rotated mediall~.~ All therapists serving as testers re- ceived the written instructions and photographs of the PF alignment tests approximately 2 weeks prior to data Figure 1. Patellofemoral alignment test for medial/lateral displacement. Markings collection. This procedure allowed on the patient's skin in the photograph were for illustrative purposes and were not used testers the opportunity to practice the by testers during the study. evaluation procedures prior to partici- pation in the study. We provided alignment tests are based on descrip- medial epicondyle to the thumbs will testers with the opportunity to ask tions from M c C o ~ e l lThe wording .~ be less than the distance from the questions regarding interpretations of in following descriptions is exactly as lateral epicondyle to the the written instructions on the day that they were presented to the testers. testing was initiated at each clinic. Mediallateral tiff. The degree of MediallIatemI displacement. Lateral medial or lateral patellar tilting is de- Initially, an attempt was made to select displacement is determined by palpat- termined by comparing the height of a random pair of therapists to test ing the medial and lateral femoral the medial patellar border with that of each patient. Random pairing was not epicondyles with the index fingers and the lateral patellar border. The exam- maintained, however, due to schedul- simultaneously palpating the rnidpa- iner places his or her thumb and in- ing conflicts for both testers and pa- tefla with the thumbs (Fig. 1). Nor- dex finger on the medial and lateral tients. One facility had only two thera- mally, the distance between the index borders of the patella (Fig. 2). Both pists participating in the study, so fingers and the thumbs should be digits should be of equal height. If the random pairing was not possible. approximately the same.4If a lateral digit palpating the medial border is displacement is present, then the dis- more anterior than the lateral border, Paired testers performed the PF align- tance from the index finger palpating then the patella is tdted laterally.4 If ment tests independently. The thera- the lateral epicondyle to the thumbs the digit palpating the lateral border is pist assigned to treat the subject at the will be less than the distance from the more anterior than the medial border, time of referral to physical therapy finger palpating the medial epicondyle then the patella is tilted medially.4 was identified as examiner 1. The to the thumbs.4If a medial displace- paired thempist was identified as ex- ment is present, the distance from the aminer 2. Examiner 1 performed the tests of PF alignment first, and then Physical Therapy / Volume 75, Number 2 / February 1995
- 4. to prevent a tester from obtaining test results o r information about the exam- ination process from the other testers. One individual from each participating facility was designated as the data- collection coordinator. This person collected examination result forms from the examiners, placed the f o m in an envelope, and returned these forms to us. This procedure was done in an attempt to maintain confidential- ity of the examination results. Data Analysis Intertester reliability was determined by calculating kappa coeficients, which are appropriate for norninal- level data.9 The kappa coefficient is based on the percentage of agreement between repeated assessments that has been corrected for chance Figure 2. Patellofmoral alignment test for mediaVlatera1 tilt. Markings on the agreement. patient's skin in the photograph were for illustrativepurposes and were not used by testers during the study. examiner 2 performed the tests within The testers were instructed not to There were a total of 66 paired assess- one treatment session of examiner 1. discuss the evaluation findings on any ments for each test of PF alignment. Most often, testing was performed by subjects until the entire study was The percentages of agreement and both testers during the same session. completed. This instruction was given kappa coefficients are reported in Table 2. The percentages of agree- ment ranged from 44% to 71%. The kappa coeficients ranged from .10 to .36. The low kappa coefficients suggest the reliability of measurements of PF alignment ranged from poor (.00-. 10) to fair (.20-.40), according to criteria proposed by Landis and Koch.10 The kappa coeficients were consistently lower than the percentage-of- agreement values because kappa coefficients represent the proportion of agreement after chance agreement is removed. The kappa coefficient may be artili- cially lowered or elevated if there is insufficient variability in the phenom- ena being assessed." This artficially lowered or elevated value may result in either an underestimation or overes- Figure 3. Patellofmoral alignment test for anterior tilt. Markings on the patient's timation of reliabilty.For in skin in the photograph were for illustrativepurposes and were not used by testers dur- the evaluation of medial/lateral dis- ing the study. placement, there are three possible 12/ 87 Physical Therapy / Volume 75, Number 2 / February 1995
- 5. - Table 3. Distn'bution of Paired Judg- ments for MediaULateral Displacement Disdacement Medial None Lateral Total Medial 5 3 3 11 None 4 10 10 24 Lateral 3 9 19 31 Total 12 22 32 tal totals increase from left to right) for each table"; thus, our kappa values may be artificially lowered. We d o not, however, consider the percentage of agreement to be high for any of the tests, and therefore kappa would probably not be seriously affected. Hence, we believe our kappa values - Figure 4. Patellofernoral alignment test for medial4ateral rotation. Markings on reflect the degree of reliability o the f the patient's skin in the photograph were for illustrative purposes and were not used by PF alignment measurements, and they testers during the study. are poor to fair at best. choices: medal displacement, lateral ability. A lack of variability would displacement, or no displacement. If tesult in a high degree of agreement the sarn~Ae consisted o subjects who f being attributed to chance and, there- were equally distributed among each fore, a low kappa coefficient. of the three possible test results, then the sample would demonstmte reason- According to Feinstein and Ciccherti,ll Table 4. Di~tributionof Paired Judg- able variability in the phenomena there is no "gold standard" by which ments for Media~katemlTilting being studed and the kappa coeffi- adequate variability of scores is deter- cient would be appropriate. However, mined when using kappa. They sug- Tiltina if almost all subjects in the sample gest that analysis of the marginal totals Medial None Lateral Total of scores can indicate whether kappa - exhibited a lateral displacement, then the sample would lack adequate vari- will be arhficially elevated or lowered. If the marginal totals are imbalanced Medial 0 0 1 1 in their distribution, then kappa will -- None 3 11 11 25 be altered. If marginal totals are sym- Lateral 3 9 28 40 metrically imbalanced, then kappa will Total 6 20 40 Table 2. Kappa statatic (Percentage be lowered and will tend to underesti- of ~greement Parentheses) for Patel- in mate reliability. If marginal totals are lofemoral Alignment Evaluation asymmetrically imbalanced, kappa will Procedi~res be elevated and will tend to overesti- mate reliability. The effect of marginal Table 5. Distribution of Paired Judg- Kappa total imbalances on the kappa statistic ments for MediaULateral Rotation (Percentage Of is probably most serious in cases in Procedure Ag-ment) which a high percentage o agreement f Rotation exists. Medial None Lateral Total Medial/lateral displacement .10 (44%) The distributions o judgments for f MediaVlateraltilt .21 (59%) each test of PF alignment are shown Medial 2 1 6 9 Anterior/posterior tilt .24 (71%) in Tables 3 through 6. The marginal None 3 17 5 25 MediaVlateral totals (in italics) indicate that there is a Lateral 4 7 21 32 rotat~on .36 (61%) symmetrical imbalance (vertical totals Total 9 25 32 increase from top to bottom, horizon- Physical Therapy /Volume 75, Number 2 / February 1995
- 6. - Table 6. Distribution o Paired Judg- ments for Anterior Tilting Anterior f None Total interpretation of the instructions by providing a question-and-answer pe- riod on the day that testing was initi- ated at each clinic. This precaution would not, however, completely elimi- nate the potential for valying interpre- tations of the instructions. The written Because we have been unable to find a reliable clinical method o assessing f PF alignment, we recommend select- ing taping techniques based on the immediate response of the patient's symptom to a specific taping tech- nique. This method is not dependent on any judgment of PF alignment. The instructions given to the examiners were based on the descriptions of the critical first step in this method is to Anterior 7 8 15 identify a painful activity, such as stair procedures provided by McComeU.* None 11 40 51 Modifications to these instructions may climbing, squatting, or manually re- Total 18 48 improve the reliability of the evalua- sisted knee extension. This activity tion procedure. We believe, however, serves as the basis for judging the that an evaluation that is based on effectof the tape on the patient's Several factors may have contributed palpation of nondiscrete bony land- symptoms. We then systematically to the poor reliability of the PF align- marks and visual inspection o rela- f apply specific taping techniques until ment measurements in t i study. hs tively small bony segments is inher- the patient's symptoms are signifi- Perhaps the most influential factor is ently unreliable. cantly reduced or completely that testers were required to palpate alleviated. bony landmarks that may be d&cult Another potential source o error was f to palpate accurately. The examination that examiner 1 always had knowl- Conclusions procedure for mediavlateral displace- edge of the physician's diagnosis for ment serves as an example. This pro- the patient because examiner 1 was Four clinical tests of PF alignment cedure involves palpation of the me- the treating therapist. Unfortunately, were found to lack reliability in t i hi dial and lateral femoral epicondyles we are not certain whether examiner 2 study. Without reliability, these tests and the center of the patella. The always had this information. There- would not be useful in guiding treat- medial and lateral femoral epicondyles fore, examiner 1 may have been bi- ment decisions for PF taping-orthera- are not discrete prominences, and they ased by knowing the physician's diag- peutic exercise. Therapists are encour- vary in size and shape across indvidu- nosis prior to performing the PF aged to seek other methods to guide als. It is possible that two exarniners alignment tests. clinical decision malung for these could correctly palpate one of these treatments. structures but their finger placements Clinical lmplications may be several millimeters apart. Like- Acknowledgments wise, the shape, size, and orientation The PF alignment tests in this study o the patella varies across individuals, f were initially developed, in pafl, to We thank the physical therapy staffs at rnakmg it ditticult to accurately palpate guide clinical decisions regarding PF the following clinics in the Philadel- the center of the patella. taping procedures. Because these PF phia metropolitan area: Temple Uni- alignment tests do not exhibit a high versity Spoltsmedicine Chic, South Errors in visual inspection of the patel- degree of reliability, they may not Jersey Physical Therapy Associates, lar position with respect to the femur provide valid information that would Pennsylvania Rehab Inc, and Atlantic may have contributed to the poor guide clinical decisions for PF taping Rehabilitation Services. We extend reliability o the measurements. Be- f or therapeutic exercise. This concern special thanks to Jeff Ryan, PT, ATC, cause the bony segments of the PF does not, however, discount the use- Ned Lenny, PT, Scott Voshell, PT, and joint are relatively small, errors due to fulness of PF taping techniques. In our Deborah Tullrnan, PT, their efforts for visual estimation may have been chical experience, the PF taping in coordinating data collection at the rnagnhed. procedures described by McConnel14 participating facilities. can be effective in reducing symptoms. A l examiners were given the same l written instructions and photographs References Physical therapists may choose to use of the evaluation procedures. We other methods o determining when f 1 Kramer PG. Patella malalignment syndrome: believed that this was an acceptable and how to apply PF taping tech- a rationale to reduce excessive lateral Dres- way of standardzing the testing proce- niques. Some clinicians in our area sure. Orthop Sports Pbys Ther. 1986;a:301- dures, because many therapists learn 309. use the patellar tilt test and patellar 2 Fisher RL. Conservative treatment of patel- evaluation and treatment techniques glide test described by Kolowich et lofe~noralpain. Orrhop Clin North Am. 1986; through descriptions o the techniques f allz to guide clinical decisions regard- 17:269-272. in the literature. It may be possible ing taping. The reliability of measure- 3 Henry JH. Conservative treatment of patel- that these instructions were interpreted lofemoral subluxation. Clin Spolfs Med. 1989; ments obtained with these tests, how- R:261-278. differently across therapists. We at- ever, is also unknown. tempted to minimize problems with Physical Therapy /Volume 75, Number 2 / February 1995
- 7. 4 McConnell J. The management of chondro- 7 Woodall W, Welsh J. A biomechanical basis 10 Landis RJ, Koch GG. The measurement of malacia patellae: a long-term solution. Austra- for rehabilitation programs involving the observer agreement for categorical data. Bio- lian Journal of Physiotherapy. 1986;32:215 patellofemoral joint. J Orthop Sports Phys metrics. 1977;33:159-174. 223. 7ber. 1990;11:53%541. 11 Feinstein AR, Cicchetti DV. High agree- 5 Paulos L, Rusche K, Johnson C, Noyes FR. 8 Riddle DL, Rothstein JM. Intertester reliabil- ment but low kappa, I: the problems of two Patellar malalignment: a treatment rationale. ity of McKenzie's classfications of the syn- paradoxes. J Clin Epidemiol. 1990;43:543549. Phys 7ber. 1980;60:1624-1632. drome types present in patients with low back 12 Kolowich PA, Paulos LE, Rosenberg TD, 6 Shelton GL, Thigpen LK. Rehabilitation of pain. Spine. 1993;18:13331344. Farnsworth S. Lateral release of the patella: patellofemoral dysfunction: a review of litera- 9 Cohen J. A coefficient of agreement for indications and contraindications.Am J Sports ture. J W h o p Sports Phys 7ber. 1991;14:243 nominal scales. Educational and Psychologi- Med. 1990;18:359-365. 249. cal Measurement. 1960;20:37-46. Invited Commentary Fitzgerald and McClure are to be com- The study by Artemieff et all was skilled practitioner, manual examina- mended for their study on "the reli- modified by Norman et a1,2 who ex- tion has been found to reliably detect ability of four tests for patellofemoral amined the reliability of measurements the pathognomic segment in patients alignment." With the push to demon- obtained by five therapists assessing with spinal paha-" These articles:-" strate the r:fficacy of physical therapy, the patellar position in 20 symptomatic however, emphasize the importance there is a need to critically analyze the individuals. In this unpublished study, of the skill level of the individual ther- reliability of measurements obtained each subject was assessed by all five apist in the particular manual tech- with the assessment procedures we therapists at the beginning of the treat- nique. To improve the skill level, it use. This study should teach us to be ment session, so any tissue change may be necessary for us to examine cautious about making dogmatic state- during treatment could not influence the way manual techniques are ments on the basis of one assessment the assessment. The written instruc- learned. Feedback needs to be pre- procedure, particularly when it can be tions for palpation were more specdic cise. Lee et all2 demonstrated that shown that different therapists can in an attempt to minimize the problem immediate quantitative feedback, us- produce different results using the of bony landmark identification. The ing an oscilloscope during spinal mo- "same" procedure. We should realize results of Norman and colleagues' bilization, increased the accuracy and that in many instances these tests study demonstrated a high percentage consistency in producing a given should guide, not dictate, our treat- of agreement among the therapists, force. It is diliicult to imagine how ment and that it is the patient's re- but, because there was little variability most children could learn to play a sponse to the treatment that will direct in the data, the expected agreement musical instrument or a particular and fine-tune our treatment further. was also high. Therefore, the Kappa sport with only written instruction, no values were lower and in fact worse guidance from an instructor, and no The study by Fitzgerald and McClure than the Kappa values reported by time allocated for practice. confirms the findings of Artemieff et a1 Fitzgerald and McClure ( K = .lo-.36). on asymptomatic individuals' and of Norman et al hypothesized that the There appear to be two inherent as- N o m n et a1 on symptomatic individ- lack of reported variability of patellar sumptions in the studies examining uals.* The unpublished study by Arte- position may have occurred because the reliability of measurements o b mieff et all revealed that the reliability the examiners were expecting alter- tained by palpation: (1) The palpatory of assessing patellar position was poor ations in patellar position as all s u b skill level of all physical therapists is on all four components. Their study, jects were symptomatic. It seems that the same, and (2) all therapists will however, was performed only on whenever the reliability of measure- immediately acquire, from the written asymptomatic individuals, so it was ments involves manual exarnina tion, instructions, the same level of exper- thought that the therapists were ex- the outcome is always poor. tise. Perhaps, when learning tech- pecting abnormalities, when such niques dependent upon palpatory abnormalities perhaps did not exist. Potter and Rothsteins found poor skill, therapists need to feel, as well as Artemieff et a1 also concluded that the reliability in 11 sacroiliac joint tests be shown, examples of the extremes greatest source of error was the identi- that required accurate palpation of in the assessment so that they can fication of the bony landmarks, as no bony landmarks. It has been found on begin to develop an appreciation of single reference point was easily dis- numerous o c ~ a s i o n s that measure- ~-~ the range of possibilities. The feed- tinguishable. ments based on palpations are unreli- back given needs to be precise, and able for determining stiffness in the time must be allocated for practice to spine. However, in the hands of a improve the skill level. In doing so, Physical Therapy / Volume 75, Number 2 / February 1995