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Normative data of frontal plane patellar alignment in athletes

Luciana De Michelis Mendonça, PT, MSc Juliana Melo Ocarino, PT, ScD NatáliaFranco Netto Bittencourt, PT, MSc Thiago Ribeiro Teles Santos, PT, MSc RafaelAlmeida Barreto, PT, BPT Sérgio Teixeira Fonseca, PT, ScD

PII: S1466-853X(14)00076-5

DOI: 10.1016/j.ptsp.2014.09.003

Reference: YPTSP 630

To appear in: Physical Therapy in Sport

Received Date: 11 December 2013

Revised Date: 15 April 2014

Accepted Date: 12 September 2014

Please cite this article as: De Michelis Mendonça, L., Ocarino, J.M., Netto Bittencourt, N.F., TelesSantos, T.R., Barreto, R.A., Fonseca, S.T., Normative data of frontal plane patellar alignment in athletes,Physical Therapy in Sport (2014), doi: 10.1016/j.ptsp.2014.09.003.

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http://dx.doi.org/10.1016/j.ptsp.2014.09.003

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NORMATIVE DATA OF FRONTAL PLANE PATELLAR ALIGNMENT 1

IN ATHLETES 2

Luciana De Michelis Mendonça, PT, MSca,b, Juliana Melo Ocarino, PT, 3

ScDa,c, Natália Franco Netto Bittencourt, PT, MSca,d, Thiago Ribeiro Teles 4

Santos, PT, MSca, Rafael Almeida Barreto, PT, BPTa, Sérgio Teixeira 5

Fonseca, PT, ScDa,c. 6

a Laboratory of Sports Injuries and Prevention (LAPREV) – Universidade 7

Federal de Minas Gerais, Belo Horizonte, Minas Gerais (MG), Brazil – CEP 8

31270-901 9

b Instituto Superior de Ciências da Saúde – Belo Horizonte, MG – Brazil – 10

CEP 30494-270 11

c Departamento de Fisioterapia – Escola de Educação Física, Fisioterapia e 12

Terapia Ocupacional – Universidade Federal de Minas Gerais – Belo 13

Horizonte, MG – Brazil – CEP 31270-901 14

d Minas Tenis Clube – Belo Horizonte, MG – Brazil – CEP 30112-011 15

Corresponding author (and requests for reprints): Sérgio Teixeira Fonseca – 16

Escola de Educação Física, Fisioterapia e Terapia Ocupacional - Av. Pres. 17

Antônio Carlos, 6627 Campus - Pampulha - Belo Horizonte - MG - CEP 18

31270-901 - Universidade Federal de Minas Gerais – Brazil 19

[email protected] 20

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NORMATIVE DATA OF FRONTAL PLANE PATELLAR ALIGNMENT 1

IN ATHLETES 2

ABSTRACT 3

Objective: the objective of this study was to provide normative data of frontal 4

plane patellar alignment according to McConnell and Arno angles, verify the 5

association between theses angles and identify the presence of patellar rotation 6

in different sports modalities. Design: cross-sectional. Participants: Nine 7

participants (18 knees) were assessed in a preliminary study to verify the intra 8

and inter-examiner reliabilities of the patellar alignment measures. In the main 9

study, 230 volleyball, basketball, gymnastics and soccer athletes (460 knees) 10

were evaluated in order to obtain normative data of patellar alignment. Main 11

outcome measures: frontal plane patellar alignment (McConnell and Arno 12

angles) measured in standing position by means of photogrammetry. Results: 13

The standardized method demonstrated intra e inter-examiner reliability 14

coefficients varying from (.85 to .98). The mean McConnell and Arno angles 15

were 2.05o (±5.9) and 2.89o (±7.57), respectively. It was observed a low 16

association (r=.189, p<.000) between these angles. There was difference in 17

distribution of medial and lateral rotations, according to McConnell angle, 18

between sports modalities (p<.014). Conclusions: The proposed procedure for 19

measuring patellar alignment according to McConnell and Arno angles proved 20

to be highly reliable. This made possible the establishment of normative data 21

in a large sample of healthy athletes. 22

Keywords: patella; alignment; reliability; assessment. 23

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INTRODUCTION 25

Alterations of frontal plane patellar alignment (i.e. patellar rotation) 26

may contribute to development of clinical conditions, such as patellofemoral 27

pain syndrome and patellar tendinopathy (Powers, 2003; Mendonça, Macedo, 28

Silva & Fonseca, 2005; Wilson, 2009; Barton, Bonanno, Levinger & Menz, 29

2010; Draper et al., 2010; Lin et al., 2010; Powers, 2010; Souza et al., 2010). 30

The proposed contribution of patellar rotation to development of these 31

conditions is associated to changes in dynamic patellar alignment on the 32

femoral trochlear groove during knee flexion and extension (Draper et al., 33

2010; Lin et al., 2010; Souza et al., 2010; Wilson, Mazahery, Koh & Zhang, 34

2010), and to asymmetrical force distribution on the medial and lateral 35

retinaculum and on the medial and lateral portions of patellar tendon (Elvin et 36

al., 2009; Lin et al., 2010; Wen, 2007; Zachazewski, Magee & Quillen, 1996). 37

These asymmetries may result in overload to specific regions of the patella 38

and its tendon. Therefore, the presence of patella rotation may be considered a 39

factor that may contribute to the development or worsening of musculoskeletal 40

dysfunctions (Barton et al., 2010; Diederichs et al., 2013; Draper et al., 2010; 41

Powers, 2010; Reiman, Bolgla & Lorenz, 2009). 42

The classification of biomechanical factors as relevant or not depends 43

on the comparison with normative data. Although the literature describes 44

frontal plane changes in patellar alignment (Arno, 1990; Mendonça et al., 45

2005; Wilson et al., 2009; Zachazewski et al., 1996), there is no reported 46

normative data of this alignment to identify which values could be expected as 47

normal and those that could characterize the presence of excessive patellar 48

rotation. The existence of normative values for patellar rotation would allow 49

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clinicians to characterize the patellar alignment in a specific population to help 50

determining what could be considered clinically relevant. 51

Some measurements have been proposed to evaluate the frontal plane 52

patellar alignment (Diederichs et al., 2013; Draper et al., 2010; MacIntyre et 53

al., 2008). Magnetic resonance imaging and computed tomography, for 54

example, are exams that could be used as measurements of patellar rotation 55

(Diederichs et al., 2013; Draper et al., 2010; MacIntyre et al., 2008). If on one 56

hand, these exams allow a tridimensional analysis of patellar alignment, on the 57

other hand, they have low applicability in clinical context due to high costs 58

(Draper et al., 2010; Wilson, 2007) and to the non-functional information they 59

provide as a result of the patient positioning during examination (Diederichs et 60

al., 2013). Thus, in clinical settings, some methods involving visual estimation 61

and palpation have been proposed to evaluate the patellar alignment (Diveta & 62

Volgelbach, 1992; Zachazewski et al., 1996; Ehrat, 1994). However, these 63

methods have low reliability (Diveta & Volgelbach, 1992; Tomsich, Nitz, 64

Threlkeld & Shapiro, 1996; Wilson, 2007), preventing the establishment of 65

normative values. 66

In order to allow the quantification of frontal plane patellar alignment, 67

two clinically feasible methods have been proposed: McConnell and Arno 68

angles (Arno, 1990; Diveta & Volgelbach, 1992; Ehrat, 1994; Mendonça et 69

al., 2005; Watson et al., 1999). The former considers the patellar alignment 70

relative to the femur and the latter relative to the tibia. The first point to be 71

raised is that, since each angle considers the patellar alignment relative to 72

different references (segments), do they measure exactly the same aspect of 73

patellar alignment? The second point is relative to the patient positioning 74

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during the test. Traditionally, the patient position during the evaluation of both 75

angles is in relaxed supine lying. However, as distal (e.g. shank and foot) and 76

proximal body segments (e.g. hip and thigh) may influence patellar alignment 77

through retinaculum tensioning (Barton et al., 2010; Mendonça et al., 2005; 78

Reiman et al., 2009), the angles of patellar rotation obtained with traditional 79

positioning (supine with knee extension) may not represent the real patellar 80

position in functional situations. Therefore, the measurement of patellar 81

alignment has to consider a more functional position in order to take into 82

account these biomechanical influences. A position that considers the 83

influence of the tensioning of the patellar retinaculum is standing with semi 84

flexed knees (in a position around 30°) (Wilson et al., 2009; Draper et al., 85

2010; Souza et al., 2010). 86

The use of normative data in clinical practice, especially in sports, is 87

facilitated when the method chosen is fast and easily applied, in order to allow 88

the evaluation of a large number of individuals in a short period (e.g. athletes 89

preseason screening). In addition, standardization and adequate reliability of 90

the method is a precondition to the test to be used. Thus, the main purposes of 91

this study were (1) to generate normative data to characterize frontal plane 92

patellar alignment in athletes (2) verify the association between McConnell 93

and Arno angles, and (3) verify the distribution of the types of frontal plane 94

patellar alignments in different sports modalities. To achieve this aim, a 95

preliminary methodological study was carried out to evaluate the reliability of 96

the proposed standardized method to measure the McConnell and Arno angles. 97

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METHODS 100

Two studies were carried out in order to attain the objectives. First, a 101

methodological study was performed to develop a method to measure the 102

McConnell and Arno angles in standing position and to determine the inter 103

and intra examiners reliability. Second, the main study was carried out with a 104

larger number of athletes, in order to obtain normative data on frontal plane 105

patellar alignment. In both studies, the procedures to measure the patellar 106

alignment were the same. Participants with history of injuries or surgery in the 107

lower limbs extremity in the previous six months were not included in any of 108

the studies. Informed consent was obtained for all participants and the rights 109

of subjects were protected in both studies. 110

Reliability Study 111

Nine volunteers (18 knees) who practiced sports activities five times a 112

week took part in this study. The sample was comprised of 3 men and 6 113

women (mean age of 22.66 ± 2.54 years; mean height of 1.68 ± 0.79 m; and 114

mean body mass of 64.88 ± 8.32 kg). Two examiners assessed the 115

participants. In order to allow the intra-examiner reliability assessment, each 116

examiner measured the same participant twice with an interval of three days. 117

In the same evaluation session, the measures were done with 15-minute 118

intervals between examiners in order to avoid fatigue of the lower limb 119

muscles. The examiners could not access the results obtained by each other. A 120

third examiner removed all marks on the athlete’s skin (more details in 121

patellar alignment measurement description) during the interval between the 122

evaluations of each examiner to make sure that they could not see the marks 123

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made by each other. The second measurement of each examiner was used for 124

inter-examiner reliability analysis. 125

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Normative Data Study 127

After the reliability investigation, the two examiners evaluated two 128

hundred and thirty athletes (460 knees) of different sports: volleyball (n= 68), 129

basketball (n= 50), gymnastics (n= 59) and soccer (n = 53). Demographic data 130

of each modality are presented in TABLE 1. 131

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Insert TABLE 1 about here 133

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Patellar alignment measurement 135

To evaluate the frontal plane patellar alignment, reflective markers 136

were attached bilaterally to the anterior superior iliac spine (ASIS), femoral 137

epicondyles, midpoint of the patellar base (determined with a measuring tape), 138

inferior pole (apex) of the patella and tibial tuberosity. The markers’ 139

placements and photographic records were determined with the subject in 140

bipedal standing with the knees flexed at 30o degrees (measured with universal 141

goniometer) (FIGURE 1). The knee was positioned in flexion to allow the 142

assessment of patellar alignment under the influence of patellar retinaculum 143

tensioning (Mendonça et al., 2005; Wilson et al., 2009; Draper et al., 2010; 144

Souza et al., 2010) and to avoid overestimation of Arno angle due to external 145

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rotation of the tibia due to knee extension. While maintaining this position, the 146

individual was asked to keep a wooden stick, placed over the shoulders, 147

aligned parallel to the wall and floor. This procedure was used to ensure 148

proper subject positioning without trunk rotation. Photographic records of the 149

subjects were performed with a digital camera (SC-D385, Samsung®) 150

positioned parallel to the ground and placed perpendicular to the frontal plane 151

of the athlete. The subjects were evaluated barefoot. 152

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Insert FIGURE 1 about here 154

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The McConnell and Arno angles were used to quantify frontal plane 156

patellar alignment. Initially, the midpoint between the femoral epicondyles, 157

the femoral bisection (line between the ASIS marker and midpoint between 158

femoral epicondyles), the patellar bisection (line between midpoint of the base 159

and inferior pole of the patella) and patellar tendon bisection (line between the 160

inferior pole of the patella and tibial tuberosity) were determined (FIGURES 2 161

and 3). The McConnell angle was defined as the angle between the femoral 162

bisection and patellar bisection (FIGURE 2). The Arno angle was defined as 163

the angle between the patellar bisection and patellar tendon bisection 164

(FIGURE 3) (Mendonça et al., 2005). The bisections and the calculation of the 165

angles (in degrees) were performed by an examiner who was not involved in 166

data collection using the software Simi Motion Twinner®. 167

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Insert FIGURES 2 and 3 about here 169

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In addition to the mean angle calculated for both McConnell and Arno 171

measures, the patellar alignment was characterized relative the direction of 172

rotation. The anatomic reference used to this classification was the inferior 173

pole of the patella. Medial rotation of the patella was defined as present when 174

the inferior pole of the patella was pointed medially to the femoral bisection 175

(McConnell angle) or to the patellar tendon bisection (Arno angle) and 176

received negative values. When the inferior pole of the patella was pointed 177

laterally to the femoral or patellar tendon bisections, it was defined as lateral 178

rotation according to McConnell and Arno respectively. Lateral rotation 179

received positive values (Arno, 1990; Watson et al., 1999). Values between 180

+1o and -1o were classified as neutral patellar alignment in the frontal plane. 181

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Statistical Analysis 183

In the reliability study, Intraclass correlation coefficients (ICC3,1) were 184

used to determine intra- and inter-examiners reliability. In addition, the 185

Standard Error of Measurement (SEM) of each measure was calculated. In the 186

Normative Data study, descriptive statistics were used to characterize the 187

patellar alignment in the frontal plane, considering both lower limbs (460 188

lower limbs). Pearson’s correlation was carried out to investigate the 189

association between McConnell and Arno angles. Chi-square tests (X2) were 190

used to verify the distribution of patellar rotation type, according each angle 191

measured, between the sports modality assessed in this study. The alpha level 192

for the analyses was set at 0.05. 193

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RESULTS 195

Reliability Study 196

The proposed method to measure the McConnell and Arno angles had 197

excellent intra and inter examiners reliabilities (ICC3,1 varied from 0.85 to 198

0.98). The SEM values varied from 0.08 to 0.33 degrees. The means, standard 199

deviations of the patellar alignment angles, reliability coefficients and SEM 200

are presented in TABLE 2. 201

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Normative Study 205

Descriptive data was obtained considering the magnitude of patellar 206

alignment and the classification of patellar alignment, with their respective 207

magnitude, according to McConnell and Arno angles measures. These values 208

are presented in TABLE 3. 209

Pearson’s correlation coefficient demonstrated low association 210

between McConnell and Arno angles (r = 0.189, p <0.0001), confirming that 211

they measure different dimensions of patellar alignment. However, differences 212

were found in type distribution between sports modalities for McConnell 213

angle (X2=15.99; p= .014). Post-hoc analysis showed that volleyball athletes 214

presented greater proportion of patellar medial rotation compared to gymnastic 215

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athletes (details on TABLE 3). Arno angle showed no difference in the type 216

distribution between sports modalities (X2=4.47; p= .613). 217

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DISCUSSION 235

The present study introduced the standardization of a method to 236

measure the McConnell and Arno angles in standing position with semi flexed 237

knee, using photogrammetry. The results demonstrated that this method had 238

excellent intra and inter reliability and low standard error of measurement. In 239

addition, this study allowed the characterization of the frontal plane patellar 240

alignment in 230 subjects (460 lower limbs) from different sports modalities. 241

The high reliability and practical applicability of this method indicates that the 242

clinical evaluation of McConnell and Arno angles can be inserted in 243

preseasons assessments involving a large number of athletes. In addition, the 244

obtained values in these evaluations can be compared with the normative data 245

provided by the presented study. This will make it possible to evaluate the 246

contribution of the frontal plane patellar alignment to the occurrence of 247

patellofemoral joint disorders. 248

The two-dimensional measurement method of patellar alignment had 249

excellent intra and inter-rater reliability (ICC ranging from 0.85 to 0.98), 250

despite of small sample size assessed in the methodological study. Studies that 251

investigate psychometric properties of patellar alignment measurements did 252

not show adequate reliability, especially inter-examiner (Diveta & Vogelbach, 253

1992; Tomsich et al., 1996). Diveta & Vogelbach (1992) reported inter-rater 254

reliability coefficients of ICC= -0.01 for Arno angle, measured with a 255

goniometer with the subject in supine position (Diveta & Vogelbach, 1992). 256

Tomsich et al (1996) measured patellar rotation with goniometer and also 257

showed low intra and inter-examiner coefficients for McConnell (ICC 258

intra=0.52 and ICC inter=0.003) and Arno angles (ICC intra=0.61 and ICC 259

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inter=0.49) (Tomsich et al., 1996). As the authors argued, factors such as lack 260

of examiners experience, little time devoted to training the measures and 261

restricted time for the examiner to define the patellar alignment may explain 262

the low reliability observed in these studies (Diveta & Vogelbach, 1992; 263

Tomsich et al., 1996). On the other hand, the standardized method and the 264

image analysis proposed in the present study achieved high reliability. In 265

addition to the high reliability, the method used in the present study had low 266

measurement error. The SEM values varied from 0.06o to 0.33o and from 0.08o 267

to 0.29o, respectively for Arno and McConnell angles. The SEM values 268

obtained in the present study indicate an expected spread around a given result 269

of less than one degree, which reinforces the appropriateness of this 270

standardized measure. 271

The measurements used in the present study involved palpation of 272

anatomic landmarks for reflective markers placement as others methods 273

reported in literature (Diveta & Vogelbach, 1992; Tomsich et al., 1996; 274

Mendonça et al., 2005). Therefore, the high reliability depends on palpation 275

training of these landmarks in order to the evaluator to become more accurate 276

and reliable. Palpation performed with the individual in standing seems to 277

have the potential to reduce errors of placing anatomical marks by the 278

examiner. In this position, the patella is more stable by muscular action and 279

patellar retinaculum tensioning, due to the knee flexion, which also highlights 280

the patella contours. In addition, some procedures were established in the 281

present study to prevent anatomical variations to hamper patellar palpation 282

and the correct identification of markers’ location. For example, to identify the 283

inferior pole of the patella, it was defined that, for those individuals with 284

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enlarged fat pads, the examiner should produce a slight superior tilt of the 285

patella, aiming to define the inferior pole contours to facilitate the 286

identification of its location for marker placement. Similarly, for the anterior 287

tibial tuberosity, it was established that the highest tuberosity’s prominence 288

should be used as reference. However, for those individuals with a flat 289

superior tibial portion, the tuberosity midpoint was defined as reference for the 290

marker placement. This standardization for location of anatomic references, 291

certainly, contributed to the excellent reliability and low measurement error 292

observed in the present study and it could be used in future studies 293

implemented to assess patellar alignment. 294

The study performed in 230 healthy athletes allowed the 295

characterization of the frontal plane patellar alignment. This large number of 296

lower limb assessed (n = 460 knees) allows the obtained values of patellar 297

alignment to be used as normative data. The mean values of patellar alignment 298

for the total sample of the study were 2.05o for McConnell and 2.98o for Arno 299

angle. Although there are no reports of normative values for these angles, it is 300

possible to compare our results with mean values reported by some reliability 301

studies. Diveta & Vogelbach (1992) found 12.3o (± 3.4o) for Arno angle in 15 302

healthy subjects. Mendonça et al. (2005) reported a mean of 7.06o (± 6.4o) for 303

McConnell and 9.1o (± 7.1o) for Arno angle in 14 healthy individuals. The 304

discrepancy of the values obtained in the present study and the values obtained 305

by Diveta & Vogelbach (1992) and Mendonça et al. (2005) can be due to 306

differences in the participant’s positioning during the test. This test positioning 307

applies more specifically to the Arno angle. Since the Arno angle considers 308

the patellar alignment relative to the tibial tuberosity, the tibial position can 309

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influence the magnitude of this angle. In supine position with knee extension, 310

the tibia is externally rotated relative the femur (knee locking mechanism), 311

which could cause an increase of the Arno angle (Zachazewski et al., 1996). In 312

the present study, as the participant was standing with the knee semi flexed 313

(30o), the tibia was not externally rotated, which could explain the smaller 314

values of the patellar alignment according to Arno angle. Another important 315

point to be stressed is that the values obtained in the studies of Diveta & 316

Vogelbach (1992) and Mendonça et al. (2005) were obtained in a small 317

sample. In addition, it should be taken into account the low reliability 318

observed by the former (ICC= -0.01) and high standard error of measurement 319

observed by the latter (SEM = 6,4º and 7,0º). 320

The present study showed significant but low association (r = 0.189) 321

between McConnell and Arno angles obtained from the 460 lower limbs 322

assessed. This result indicates that although both angles have been proposed to 323

measure patellar alignment in the frontal plane, they are, probably, measuring 324

different aspects of this alignment. In one hand, the McConnell angle may 325

inform about the influence of the patellar retinaculum on the patellar 326

positioning in relation to the femur. In this case, the patella alignment reflects 327

the stiffness distribution between medial and lateral portions of retinaculum 328

and the distribution of the resultant forces on the trochlea and patellar facets. 329

On the other hand, the Arno angle may inform about the distribution of forces 330

acting on the medial and lateral tissues related to the patellar tendon 331

(Diederichs et al., 2013). In this case, it may also inform about the overload on 332

the patellar tendon. Since each angle informs about different dimensions of the 333

patellar alignment, which might lead to different consequences of possible 334

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misalignments, both angles should be incorporated in the investigation of the 335

frontal plane patellar alignment. 336

The data showed that lateral patellar rotation was more frequent than 337

medial rotation in both angles measured. However, there was a difference in 338

the distribution of patellar rotation type across sports modalities only for the 339

McConnell angle (p= .014). Post-hoc analysis identified that volleyball players 340

had proportionally more patellar medial rotation than gymnasts (51 and 23, 341

respectively). These results suggest that the pattern of motion adopted by 342

volleyball athletes may contribute to the medially rotated patellar posture. 343

Probably, landings in volleyball involve more latero-medial forces and the 344

iliotibial band in these athletes could be more tensioned compared to 345

gymnastics athletes. Medial rotation of the patella is associated to tension on 346

iliotibial band (Merican & Amis, 2009). Therefore, retinacular tension 347

distribution may differ between these sports modalities, producing distinct 348

distribution of patellar medial rotation. 349

A limitation of the proposed method in clinical settings is the necessity 350

of data processing after athlete’s assessment to quantify the angles. 351

Specifically, it is necessary to construct a midpoint between the reflective 352

markers placed in femoral condyles in order to define femur bisection needed 353

to determine McConnell angle. Possibly, commercial photographic analysis 354

software could be not financially and logistically accessible to all examiners. 355

Future studies could investigate the correlation of the procedure used to define 356

femur bisection and those with free software or manual identification of 357

condyles midpoint by metric tape. 358

The present study established unprecedented normative values relative 359

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to fontal plane patellar alignment and the presence of patellar rotation in 360

young asymptomatic athletes. The next step would be the assessment of the 361

patellar alignment in individuals with clinical conditions as patelofemoral pain 362

and patellar tendinopathy using the same method proposed in this study. This 363

investigation would allow verifying whether patellar misalignment is present 364

or associated to these clinical conditions and, more specifically, what 365

magnitude of patellar rotation can be considered clinically relevant to 366

development of these conditions. 367

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CONCLUSION 385

The present study proposed a standardized method for measuring the 386

patellar alignment in the frontal plane using photogrammetry. This method 387

that allow the quantification of the McConnell and Arno angles had excellent 388

reliability and low standard error of measurement. This study provided 389

reference data of patellar alignment and identified presence of patellar rotation 390

in healthy athletes of different sports modalities. In addition, it was observed a 391

weak association between the McConnell and Arno angles, which suggest that 392

these angles capture different aspects of frontal plane patellar alignment. 393

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Ethical Approval: The protocol for this study was approved by The Ethics in 410

Research Committee of the Universidade Federal de Minas Gerais (Approval 411

Report number 0493.0.203.000-09). 412

Funding: This study was partially funded by the Brazilian agencies Conselho 413

Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação 414

de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG). 415

Conflict of Interest: All authors have no conflict of interest to declare. 416

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TABLES 506

507

TABLE 1: Demographic data for volleyball, basketball, gymnastics and soccer 508

athletes 509

Female/Male* Age (years) † Body mass (kg) † Height (cm) †

Volleyball 27/41 18.27 (6.73) 71.13 (17.04) 179.15 (14.35)

Basketball 0/50 14.46 (2.38) 66.94 (18.68) 176.85 (16.91)

Gymnastics 17/42 13.91 (3.53) 55.67 (18.34) 165.94 (23.03)

Soccer 24/29 17.09 (3.36) 59.94 (10.23) 168.59 (7.46)

kg = kilograms, cm = centimeters. 510

*. values indicate the frequency of each patellar alignment classification 511

†. values indicate mean (standard deviation) 512

513

514

515

516

517

518

519

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TABLE 2: Means (standard deviations – SD) of the patellar alignment 520

magnitude (in degrees), according to McConnell and Arno, reliability 521

coefficients (Intraclass Correlation Coefficient – ICC) and standard error of 522

measurement in degrees (SEM) from both measures of patellar alignment 523

obtained by the Examiners E1 ad E2 in the moments of measures 1 and 2. 524

Examiners: E1 and

E2; moment of

measure (1) and (2)

McConnell Angle Arno Angle

Mean (SD)

Intra

E1 (1)

E1(2)

E2 (1)

E2 (2)

1.53 (5.37)

1.27 (4.93)

1.15 (3.75)

.01 (3.64)

2.96 (9.76)

5.90 (8.52)

6.25 (7.39)

7.10 (3.45)

Inter

E1 (2)

E2 (2)

3.33 (2.60)

.50 (4.09)

12.94 (7.19)

10.09 (4.25)

ICC (SEM)

Intra

E1(1) x E1(2)

E2(1) x E2(2)

Inter

.97 (.08)

.92 (.17)

.95 (.26)

.98 (.06)

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E1 x E2 .85 (0,29) .90 (0,33)

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

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TABLE 3: Normative data for McConnell and Arno angles obtained from 460 542

lower limbs. The magnitude (in means and standard deviation) and the type of 543

patellar rotation are presented for each sports modality and for the total 544

sample. 545

Total Sample Volleyball Basketball Gymnastics Soccer

McConnell Angle

Mean (SD) 2.05 (5.09) 1.55 (5.68) 2.00 (4.90) 3.19 (5.06) 1.46 (4.32)

Minimum -13.80 -10.38 -10.90 -13.80 -12.28

Maximum 19.68 19.68 16.98 13.38 15.11

Medial Rotation*

125

-4.05(2.66)

51a

-4.10(2.43)

26a,b

-3.73(2.41)

23b

-4.14(3.49)

25a,b

-4.21(2.62)

Lateral Rotation*

273

5.34 (3.38)

73a

5.83 (3.82)

56a

5.42(3.35)

81a

5.85(3.07)

63a

4.04(2.95)

Neutral Rotation*

62

-.13 (.63)

12a

-.40 (.50)

18a

-.36(.59)

14a

-.18(.52)

18a

.30(.62)

Arno Angle

Mean (SD) 2.89 (7.57) 2.90 (8.86) 1.94 (6.68) 4.25 (7.61) 2.24 (6.32)

Minimum -19.94 -19.94 -14.34 -12.16 -13.13

Maximum 24.34 24.34 17.68 22.17 17.43

Medial Rotation*

121

-6.47 (4.09)

38

-8.47(4.73)

27

-5.73(4.15)

27

-5.37(2.79)

29

-5.57(3.20)

Lateral Rotation*

284

7.40 (5.19)

87

8.17(5.26)

57

6.09(4.89)

76

8.53(5.63)

64

6.14(4.23)

Neutral Rotation*

55

.28 (.43)

11

.49(.34)

16

.09(.45)

14

.11(.42)

13

.52(.29)

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* The values indicate the frequency of individuals in each category of patellar 546

alignment followed by the mean (standard deviation), in degrees. 547

Each subscript letter denotes a subset of modalities categories whose column 548

proportions do not differ significantly from each other at the .05 level for the 549

post-hoc of X2 test. 550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

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FIGURES 565

566

FIGURE 1: Subject’s position for photographic record 567

568

FIGURE 2: Building of femur (solid line) and patella (dotted line) bisections 569

to determine McConnell angle. 570

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571

FIGURE 3: Building of patellar tendon (solid line) and patella (dotted line) 572

bisections to determine Arno angle. 573

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Acknowledgements

We thank the physiotherapist of SADA-Cruzeiro volleyball team (Betim -

Brazil), Alysson Zuin, for the partnership with our research group and to help in this

study. We appreciate Minas Tênis Clube’s Health Manager, Deborah Rocha da Costa

Reis, support for this study and the Núcleo de Integração de Ciências do Esporte

(Minas Tênis Clube, Brazil) for help with logistics during data collection.

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Highlights:

• We develop a clinical method of assessing frontal plane patellar alignment.

• This method presented an excellent intra and inter-examiner reliability

• Normative data are presented and could guide assessment and rehabilitation.

• This method and can be incorporated to athletes' pre-season assessment.