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1. Introduction
The patellofemoral pain syndrome (PFPS) is a disease that is characterized by continuous pain around the anterior knee. It is caused by several factors, such as excessive use of the knee joint, cartilage injury, increased
Because women have a wider pelvis in relation to their femoral length, they are twice as likely as men to develop PFPS [6]. Consequently, knee and hip flexion causes excessive adduction and internal rotation, reducing the patellofemoral joint contact area [7]. Furthermore, women have a weaker quadriceps femoris, with a larger
Women are reported to experience more patellofemoral stress while running, jumping, landing, and climbing stairs due to the increased load during knee flexion as a result of these structural features [1, 9]. Landing, a common task performed in daily life and sports, generates shock that is 2–3 times greater than body weight [10], and the knee joints play an important role in shock absorption during landing, absorbing approximately 41% of the total shock [11]. However, small hip flexion and large internal rotation during landing direct substantial shock onto the knee joints, and the consequently greater patellofemoral stress increases the risk of an injury [12] Women with PFPS put more strain on the patellofemoral joint during single-leg squats and landing, due to excessive knee abduction, increasing their risk of anterior cruciate ligament (ACL) injury and arthritis [13–16].
As described here, the assessment of lower limb movement and balance during a dynamic task, such as a single-leg squat or landing, is a valid method for predicting the risk of potential knee injuries [17, 18]. Patients with PFPS have been reported to have unstable landing patterns during double-leg landing, compared to their healthy counterparts [19]. These patients try to reduce knee pain by increasing hip flexion. However, they have a greater tibial internal rotation moment and an anteriorly displaced center of pressure (COP) [19]. Among the various methods for assessing dynamic postural stability [20, 21], dynamic posture stability (DPS) can be used as an indicator of the ability to maintain balance during the transition from a dynamic to a static state upon landing [22].
Landing motion is a common activity in daily life, and previous research has primarily focused on the knee joint during landing. Because women with PFPS may experience changes in the movement patterns of their entire lower limbs during landing due to structural differences, not only the knee joint but also the ankle joint and hip joint must be examined [13, 23, 24]. Furthermore, studies comparing the factors of dynamic stability during landing between patients with PFPS and healthy individuals, as well as identifying the specific dynamic factors that affect the DPS, are lacking. This study is aimed at comparing the kinematic features of major lower limb joints during single-leg landing between adult women with PFPS and their healthy counterparts, as well as to identify the specific kinematic parameters that contribute to the DPS via regression analysis, to present foundational data for developing desirable landing strategies for patients with PFPS. The hypotheses of this study are as follows. First, during single-leg drop landing, the PFPS group will have a significant difference in the angles of the hip and knee joints in the frontal plane compared to the control group. Second, the kinematic parameters affecting DPS will also appear differently.
2. Materials and Methods
2.1. Study Participants
Thirty-eight women aged 20–29, with no history of lower limb joint injuries in the previous 6 months, other than PFPS, were enrolled. The participants were divided into two groups based on their orthopedic diagnosis of PFPS: the PFPS group (
Table 1
Characteristic of participants.
Variables | PFPS group ( | Normal group ( | |
Age (years) | .789 | ||
Height (cm) | .707 | ||
Weight (kg) | .139 |
Note: data are
2.2. Procedures
Drop landing is based on a study by Orishimo et al. [25], participants were instructed to perform a drop landing from a 30 cm box by slowly shifting their body weight anteriorly and landing in a free fall. Landing outside the ground force plate or stumbling on landing were considered failed attempts, and measurements were repeated in such cases. Because the left side was affected in the PFPS group, both groups were instructed to land on their left leg. To prevent injury, the participants performed 10 minutes of warm-up and practiced drop landing for 15 minutes before beginning the measurement. To ensure accurate measurements, all participants performed a single-leg drop landing and maintained balance for at least 5 seconds after landing. To improve accuracy, the analysis used the average values of three repeated measurements of successful attempts.
2.3. Data Analysis
2.3.1. Motion Analysis
During a drop landing, eight video analysis cameras (6 Eagle & 2 Raptor Camera System, Motion Analysis Corp., Santa Rosa, CA, USA) and one ground force plate (OR6-5-2000, AMTI Inc., Watertown, MA, USA) were used to collect kinematic and kinetic data from lower limb joints. The video analysis cameras were installed around the participant (anteroposterior and mediolateral), such that the entire range of motion with reference to the reference coordinates could be captured. Segment axis systems were established with the
[figure(s) omitted; refer to PDF]
Using Cortex 5 (Motion Analysis Corp., Santa Rosa, CA, USA), we processed all kinematics and kinetic data. The data was sampled at 120 frames per second. For data processing, it was smoothed using digital filtering (Butterworth Low-Pass Digital Filtering) method to remove noise errors, the point of peak vertical GRF was analyzed, and a rigid body system was used for the analysis (Figure 2). The cut-off frequency was set at 10 Hz to minimize error during data processing. We synchronized the data using an analog-digital converter (A/D convertor, NI-USB 6218, National Instruments, Hungary) for measurement and analysis to align the time points for all data.
[figure(s) omitted; refer to PDF]
2.3.2. Dynamic Postural Stability Index (DPSI)
GRF values were established with the xGRF designated as the mediolateral direction of drop landing, the yGRF as the anteroposterior direction, and the zGRF as the vertical direction off the ground. DPSI was computed based on the study by Wikstrom et al. [22]. The stability was calculated with reference to three directions (anteroposterior, mediolateral, and vertical). The stability is a mean square deviation that assesses variation around zero rather than a standard deviation that assesses variation around the mean. The medial-lateral stability index (MLSI) and anterior-posterior stability index (APSI) assess variation around zero along the mediolateral and anteroposterior axes of the force plate, and the vertical stability index (VSI) assesses the variation in vertical GRF along the vertical axis of the force plate standardized with the participant’s body weight. To ensure the accuracy of the DPSI analysis, data was collected for 3 seconds from the point of initial contact with the ground for the calculation [22, 27].
2.3.3. Statistical Analysis
All outcome variables calculated in this study were presented as mean and standard deviation using the SPSS 26.0 (IBM, Chicago, IL USA) software for Windows. Normality assumption was first checked with the Shapiro–Wilk test (
3. Results
3.1. Kinematics and Kinetics Variables
The kinematic results of lower extremity joint angles and the kinetics results were compared at the time of mGRF. Except for knee internal rotation and ankle eversion, the two groups differed significantly across all variables. When compared with the control group, the PFPS group had significantly less hip flexion, internal rotation, knee flexion, and ankle external rotation and significantly more hip abduction, knee valgus, and ankle plantarflexion. There was a significant difference in mGRF, and there was no significant difference in leg stiffness. Compared with the control group, the mGRF of the PFPS group was significantly smaller (Table 2).
Table 2
Results of kinematics and kinetics at maximum ground reaction force.
Variables | PFPS group | Control group | ||||
Kinematics (°) | Hip | Flexion | -6.539 | ≤.001 | ||
Abduction | 6.117 | ≤.001 | ||||
Internal rotation | -3.140 | .003 | ||||
Knee | Flexion | -3.523 | .001 | |||
Valgus | 2.929 | .006 | ||||
Internal rotation | .139 | .891 | ||||
Ankle | Plantarflexion | 5.602 | ≤.001 | |||
Internal rotation | -3.342 | .002 | ||||
Eversion | -.924 | .362 | ||||
Kinetics | mGRF | -7.815 | ≤.001 | |||
Leg stiffness | -1.866 | .070 |
Note: data are
3.2. DPSI Results
DPSI was compared between the groups. The PFPS group had significantly greater APSI but significantly lower MLSI compared to the control group (Table 3).
Table 3
Results of dynamic stability index.
Variables | PFPS group ( | Normal group ( | ||
APSI | 3.240 | .003 | ||
MLSI | -2.956 | .005 | ||
VSI | -.956 | .345 | ||
DPSI | -.713 | .480 |
Note: data are
3.3. Linear Regression Analysis of DPSI
Stepwise linear regression analysis was used to examine the effects of the landing motion on DPSI changes. In the control group, has been explained as having a negative effect on APSI (
[figure(s) omitted; refer to PDF]
4. Discussion
This study compared kinematics and kinetics variables and DPS during single-leg landing between the PFPS and control groups and used regression analysis to examine the effects of landing movement on DPS. We aimed to understand the kinetic features of lower limb joints and joint coordination during single-leg landing, as well as the influence of each lower limb joint on the DPS during single-leg landing in adult women with PFPS, to present foundational data for developing education about correct landing posture in patients with PFPS. As a result, the joint angle of the lower extremities and mGRF showed a significant difference between the PFPS group and the control group. In terms of DPS, the anteroposterior and mediolateral angles of the PFPS group were significantly higher than the control group, and the variables affecting the DPS were also different.
During single-leg landing, the PFPS group had less hip flexion and internal rotation and a larger abduction angle than the control group. According to studies, women with PFPS overstrain their knee joints due to valgus and hip adduction and internal rotation during knee flexion, when flexing the knee joints, and have a weaker hip abduction due to hip abductor muscle weakness [28, 29]. Pollard et al. [30] reported that people who exhibit a small hip flexion during drop landing place a greater load on the frontal plane of the knee joint, which is consistent with our findings. Participants with a small hip flexion angle use a strategy involving the knee extensor muscle, rather than the hip extensor muscle, to alleviate the shock, implying that using the hip extensor muscle is necessary to effectively use hip flexion during landing [30]. Furthermore, patients with PFPS have a weakening of the hip abduction and external rotation force [31]. Activating the hip external rotator and extensor muscles may help prevent the exacerbation of PFPS.
According to Pollard et al. [30], women with a small knee flexion angle during landing have more knee valgus than the control group. These women are thought to have compensated for the shock inflicted during single-leg drop landing through the knee valgus, similar to the PFPS group in our study who showed small knee flexion patterns during landing. Furthermore, the PFPS group’s knee valgus pattern during landing may impair the ability to maintain knee alignment due to increased internal patellofemoral pressure, which intensifies the load in a smaller contact area and potentially escalates the pressure on the patellofemoral joint [13, 32]. Additionally, individuals also have an abnormal joint position sense [33], emphasizing the importance of joint repositioning training.
To absorb the GRF produced during landing, the ankle joints must shift from plantarflexion to dorsiflexion, and such an elevation of dorsiflexion may promote the stability of landing [34, 35]. In this study, the PFPS group was found to use an unstable and limited landing strategy, with significantly greater plantarflexion and internal rotation angle during single-leg landing than the control group. This is consistent with previous findings that a small dorsiflexion angle is related to knee flexion during landing [36, 37]. Furthermore, the PFPS group in previous study appears to have had impaired shock absorption control, which is consistent with previous studies that attributed the significant reduction in sagittal plane angle during landing in women with PFPS compared to their healthy counterparts to an impairment in shock absorption control [38]. In this study, the mGRF of the PFPS group was smaller than control group, and there was no difference in leg stiffness. It is thought that the PFPS group adopted a landing strategy differently from the control group, such as knee valgus. Rather than that, shock absorption was not properly controlled.
In terms of DPSI, the PFPS group had a higher APSI than the control group. PFPS causes quadriceps femoris and hamstring weakness, which results in an anterior displacement of the COP at peak GRF during landing [19, 39]. Patients with PFPS have severe anteroposterior instability, and inducing knee extensor fatigue increases anteroposterior instability [40]. Furthermore, the PFPS group had a low MLSI, which may be related to decreased control over knee movement due to knee valgus and pain [13]. A previous study found that the PFPS group had less COP displacement during a single-leg squat, and that a 9-week physical therapy intervention reduced pain while increasing COP displacement [41]. However, because it is unclear whether DPS is associated with knee movement and the motion characteristics may differ depending on the experimental task, further research on DPS is required [42, 43].
In this study, we used stepwise multiple regression to determine which kinematic variables best predict DPS. Knee flexion predicted APSI negatively while knee internal rotation predicted MLSI positively in the control group. A small amount of maximal knee flexion during landing may increase the shock to the lower limbs, and studies have shown that this is a poor landing strategy [44, 45]. Previous studies have found that stronger knee flexor and extensor muscles, as well as better proprioception, result in a greater knee flexion angle at initial grounding [46]. In another study, four weeks of plyometric and core training resulted in increased knee flexion and decreased internal rotation, which were attributed to lower knee joint loads [47]. Our findings suggest that increasing knee flexion while decreasing internal rotation is a strategy that promotes stability.
In the PFPS group, ankle plantarflexion was a positive predictor of MLSI, with MLSI increasing as ankle plantarflexion increased. Fong et al. [48] found that a small passive ankle dorsiflexion range of motion (ROM) can lead to large plantarflexion at landing, statistically significant high GRF and knee valgus, and small knee flexion, in a study on the correlation between passive ankle dorsiflexion ROM and landing. Furthermore, single-leg landing with a fatigued leg increases ankle plantarflexion and knee flexion, which is a compensatory strategy for fatigue-induced balance impairment and muscle weakness [34]. The PFPS group had large ankle plantarflexion and small knee flexion at peak GRF in this study, which can be attributed to the use of an ankle strategy during landing due to impaired knee motor control.
5. Limitation
The limitations of this study are as follows. Practicing single-leg drop landings for 15 minutes prior to the experiment may have affected the individual’s pain level in this experiment. The control group may not have been affected, but the PFPS group may have been affected by the pain and landed with strategy to minimize the impact on the knee. In this study, the patellofemoral joint compression force was not measured directly, but was implied by the knee joint flexion angle. Further investigation in this area is needed in future studies. As a way to improve the landing strategy of the PFPS group, it may be helpful to practice the landing motion itself, which not only improves muscles strength but also improves coordination of the lower extremities.
6. Conclusions
This study observed that the PFPS group sustained more shock on their knees during landing compared to the control group. Also, while the control group used the knee and hip joint in the landing strategy, the PFPS group used the ankle strategy to compensate for the small flexion angle of the knee and hip joint. Individuals with PFPS use an unstable landing strategy, which causes an imbalance among the lower limb joints and raises knee pressure. To avoid this, the hip abductor, external rotator, and extensor muscles must be strengthened to allow for hip flexion. Furthermore, strategies for strengthening ankle dorsiflexion and activating the knee and hip flexors are required to correct the ankle-based landing strategy, and joint repositioning training should be performed to prevent pressure build-up due to abnormal joint position. In summary, it will be helpful to selectively classify the occurrence of PFPS through the analysis of the landing motion of adult women in this study and to develop rehabilitation training focusing on PFPS.
Acknowledgments
The authors would like to thank the participants for their time and commitment to this research. This work was supported by Incheon National University Research Grant (2019-0100).
[1] D. Sisk, M. Fredericson, "Update of risk factors, diagnosis, and management of patellofemoral pain," Current Reviews in Musculoskeletal Medicine, vol. 12 no. 4, pp. 534-541, DOI: 10.1007/s12178-019-09593-z, 2019.
[2] W. Al-Hakim, P. K. Jaiswal, W. Khan, D. Johnstone, "The non-operative treatment of anterior knee pain," The Open Orthopaedics Journal, vol. 6 no. 1, pp. 320-326, DOI: 10.2174/1874325001206010320, 2012.
[3] W. Petersen, A. Ellermann, A. Gösele-Koppenburg, R. Best, I. V. Rembitzki, G.-P. Brüggemann, C. Liebau, "Patellofemoral pain syndrome," Knee Surgery, Sports Traumatology, Arthroscopy, vol. 22 no. 10, pp. 2264-2274, DOI: 10.1007/s00167-013-2759-6, 2014.
[4] B. E. Smith, P. Hendrick, P. Logan, "Patellofemoral pain: challenging current practice - a case report," Manual Therapy, vol. 22, pp. 216-219, DOI: 10.1016/j.math.2015.09.002, 2016.
[5] E. Stathopulu, E. Baildam, "Anterior knee pain: a long-term follow-up," Rheumatology, vol. 42 no. 2, pp. 380-382, DOI: 10.1093/rheumatology/keg093, 2003.
[6] B. Noehren, M. B. Pohl, Z. Sanchez, T. Cunningham, C. Lattermann, "Proximal and distal kinematics in female runners with patellofemoral pain," Clinical biomechanics, vol. 27 no. 4, pp. 366-371, DOI: 10.1016/j.clinbiomech.2011.10.005, 2012.
[7] T. G. Almonroeder, L. C. Benson, "Sex differences in lower extremity kinematics and patellofemoral kinetics during running," Journal of Sports Sciences, vol. 35 no. 16, pp. 1575-1581, DOI: 10.1080/02640414.2016.1225972, 2017.
[8] J. Stephen, A. Alva, P. Lumpaopong, A. Williams, A. A. Amis, "A cadaveric model to evaluate the effect of unloading the medial quadriceps on patellar tracking and patellofemoral joint pressure and stability," Journal of Experimental Orthopaedics, vol. 5 no. 1,DOI: 10.1186/s40634-018-0150-8, 2018.
[9] L. Zavala, V. Flores, J. A. Cotter, J. Becker, "Patellofemoral joint kinetics in females when using different depths and loads during the barbell back squat," European Journal of Sport Science, vol. 21 no. 7, pp. 976-984, DOI: 10.1080/17461391.2020.1806935, 2021.
[10] K. Jeon, K. Kim, N. Kang, "Leg stiffness control during drop landing movement in individuals with mechanical and functional ankle disabilities," Sports Biomechanics,DOI: 10.1080/14763141.2020.1726997, 2020.
[11] M. J. Decker, M. R. Torry, D. J. Wyland, W. I. Sterett, J. R. Steadman, "Gender differences in lower extremity kinematics, kinetics and energy absorption during landing," Clinical biomechanics, vol. 18 no. 7, pp. 662-669, DOI: 10.1016/S0268-0033(03)00090-1, 2003.
[12] C. M. Powers, "The influence of abnormal hip mechanics on knee injury: a biomechanical perspective," Journal of Orthopaedic & Sports Physical Therapy, vol. 40 no. 2, pp. 42-51, DOI: 10.2519/jospt.2010.3337, 2010.
[13] L. Herrington, "Knee valgus angle during single leg squat and landing in patellofemoral pain patients and controls," The Knee, vol. 21 no. 2, pp. 514-517, DOI: 10.1016/j.knee.2013.11.011, 2014.
[14] E. Magalhães, T. Y. Fukuda, S. N. Sacramento, A. Forgas, M. Cohen, R. J. Abdalla, "A comparison of hip strength between sedentary females with and without patellofemoral pain syndrome," Journal of Orthopaedic & Sports Physical Therapy, vol. 40 no. 10, pp. 641-647, DOI: 10.2519/jospt.2010.3120, 2010.
[15] H. Numata, J. Nakase, K. Kitaoka, Y. Shima, T. Oshima, Y. Takata, K. Shimozaki, H. Tsuchiya, "Two-dimensional motion analysis of dynamic knee valgus identifies female high school athletes at risk of non-contact anterior cruciate ligament injury," Knee Surgery, Sports Traumatology, Arthroscopy, vol. 26 no. 2, pp. 442-447, DOI: 10.1007/s00167-017-4681-9, 2018.
[16] K. A. Russell, R. M. Palmieri, S. M. Zinder, C. D. Ingersoll, "Sex differences in valgus knee angle during a single-leg drop jump," Journal of Athletic Training, vol. 41 no. 2, pp. 166-171, 2006.
[17] M. K. Chevidikunnan, A. Al Saif, R. A. Gaowgzeh, K. A. Mamdouh, "Effectiveness of core muscle strengthening for improving pain and dynamic balance among female patients with patellofemoral pain syndrome," Journal of Physical Therapy Science, vol. 28 no. 5, pp. 1518-1523, DOI: 10.1589/jpts.28.1518, 2016.
[18] V. Ugalde, C. Brockman, Z. Bailowitz, C. D. Pollard, "Single leg squat test and its relationship to dynamic knee valgus and injury risk screening," Pm&r, vol. 7 no. 3, pp. 229-235, DOI: 10.1016/j.pmrj.2014.08.361, 2015.
[19] K. Jeon, S. Yeom, "Effects of kinematics and kinetics of the lower extremities joint during drop landing in adult women with patellofemoral pain syndrome," Korean Journal of Sport Biomechanics, vol. 31 no. 1, pp. 64-71, 2021.
[20] L. Kanko, T. Birmingham, D. Bryant, K. Gillanders, K. Lemmon, R. Chan, M. Postic, J. Giffin, "The star excursion balance test is a reliable and valid outcome measure for patients with knee osteoarthritis," Osteoarthritis and Cartilage, vol. 27 no. 4, pp. 580-585, DOI: 10.1016/j.joca.2018.11.012, 2019.
[21] E. A. Wikstrom, M. E. Powers, M. D. Tillman, "Dynamic stabilization time after isokinetic and functional fatigue," Journal of Athletic Training, vol. 39 no. 3, pp. 247-253, 2004.
[22] E. A. Wikstrom, M. D. Tillman, A. N. Smith, P. A. Borsa, "A new force-plate technology measure of dynamic postural stability: the dynamic postural stability index," Journal of Aathletic Training, vol. 40 no. 4, 2005.
[23] J. Park, W. M. Denning, J. D. Pitt, D. Francom, J. T. Hopkins, M. K. Seeley, "Effects of experimental anterior knee pain on muscle activation during landing and jumping performed at various intensities," Journal of Sport Rehabilitation, vol. 26 no. 1, pp. 78-93, DOI: 10.1123/jsr.2015-0119, 2017.
[24] L. C. Schmitt, M. V. Paterno, K. R. Ford, G. D. Myer, T. E. Hewett, "Strength asymmetry and landing mechanics at return to sport after anterior cruciate ligament reconstruction," Medicine and Science in Sports and Exercise, vol. 47 no. 7, pp. 1426-1434, DOI: 10.1249/MSS.0000000000000560, 2015.
[25] K. F. Orishimo, M. Liederbach, I. J. Kremenic, M. Hagins, E. Pappas, "Comparison of landing biomechanics between male and female dancers and athletes, part 1: influence of sex on risk of anterior cruciate ligament injury," The American Journal of Sports Medicine, vol. 42 no. 5, pp. 1082-1088, DOI: 10.1177/0363546514523928, 2014.
[26] M. Kadaba, H. Ramakrishnan, M. Wootten, J. Gainey, G. Gorton, G. Cochran, "Repeatability of kinematic, kinetic, and electromyographic data in normal adult gait," Journal of Orthopaedic Research, vol. 7 no. 6, pp. 849-860, DOI: 10.1002/jor.1100070611, 1989.
[27] E. Wikstrom, M. Tillman, T. Chmielewski, J. Cauraugh, K. Naugle, P. Borsa, "Dynamic postural control but not mechanical stability differs among those with and without chronic ankle instability," Scandinavian Journal of Medicine & Science in Sports, vol. 20 no. 1, pp. e137-e144, DOI: 10.1111/j.1600-0838.2009.00929.x, 2010.
[28] J. Van Cant, C. Pineux, L. Pitance, V. Feipel, "Hip muscle strength and endurance in females with patellofemoral pain: a systematic review with meta-analysis," International Journal of Sports Physical Therapy, vol. 9 no. 5, pp. 564-582, 2014.
[29] M. R. Prins, P. Van der Wurff, "Females with patellofemoral pain syndrome have weak hip muscles: a systematic review," The Australian Journal of Physiotherapy, vol. 55 no. 1,DOI: 10.1016/S0004-9514(09)70055-8, 2009.
[30] C. K. Pollard, S. M. Sigward, C. M. Powers, "Limited hip and knee flexion during landing is associated with increased frontal plane knee motion and moments," Clinical biomechanics, vol. 25 no. 2, pp. 142-146, DOI: 10.1016/j.clinbiomech.2009.10.005, 2010.
[31] R. J. van Arkel, L. Modenese, A. T. Phillips, J. R. Jeffers, "Hip abduction can prevent posterior edge loading of hip replacements," Journal of Orthopaedic Research, vol. 31 no. 8, pp. 1172-1179, DOI: 10.1002/jor.22364, 2013.
[32] T. Q. Lee, G. Morris, R. P. Csintalan, "The influence of tibial and femoral rotation on patellofemoral contact area and pressure," Journal of Orthopaedic & Sports Physical Therapy, vol. 33 no. 11, pp. 686-693, DOI: 10.2519/jospt.2003.33.11.686, 2003.
[33] V. Baker, K. Bennell, B. Stillman, S. Cowan, K. Crossley, "Abnormal knee joint position sense in individuals with patellofemoral pain syndrome," Journal of Orthopaedic Research, vol. 20 no. 2, pp. 208-214, DOI: 10.1016/S0736-0266(01)00106-1, 2002.
[34] D. M. Brazen, M. K. Todd, J. P. Ambegaonkar, R. Wunderlich, C. Peterson, "The effect of fatigue on landing biomechanics in single-leg drop landings," Clinical Journal of Sport Medicine, vol. 20 no. 4, pp. 286-292, DOI: 10.1097/JSM.0b013e3181e8f7dc, 2010.
[35] K. Kim, K. Jeon, "Comparisons of knee and ankle joint angles and ground reaction force according to functional differences during single-leg drop landing," Journal of Physical Therapy Science, vol. 28 no. 4, pp. 1150-1154, DOI: 10.1589/jpts.28.1150, 2016.
[36] M. C. Hoch, K. E. Farwell, S. L. Gaven, J. T. Weinhandl, "Weight-bearing dorsiflexion range of motion and landing biomechanics in individuals with chronic ankle instability," Journal of Athletic Training, vol. 50 no. 8, pp. 833-839, DOI: 10.4085/1062-6050-50.5.07, 2015.
[37] P. Malloy, A. Morgan, C. Meinerz, C. Geiser, K. Kipp, "The association of dorsiflexion flexibility on knee kinematics and kinetics during a drop vertical jump in healthy female athletes," Knee Surgery, Sports Traumatology, Arthroscopy, vol. 23 no. 12, pp. 3550-3555, DOI: 10.1007/s00167-014-3222-z, 2015.
[38] G. S. Nunes, C. J. Barton, F. V. Serrao, "Females with patellofemoral pain have impaired impact absorption during a single-legged drop vertical jump," Gait & Posture, vol. 68, pp. 346-351, DOI: 10.1016/j.gaitpost.2018.12.013, 2019.
[39] H. Guney, I. Yuksel, D. Kaya, M. N. Doral, "Correlation between quadriceps to hamstring ratio and functional outcomes in patellofemoral pain," The Knee, vol. 23 no. 4, pp. 610-615, DOI: 10.1016/j.knee.2016.04.004, 2016.
[40] H. Negahban, M. Etemadi, S. Naghibi, A. Emrani, M. J. S. Yazdi, R. Salehi, A. M. Bousari, "The effects of muscle fatigue on dynamic standing balance in people with and without patellofemoral pain syndrome," Gait & Posture, vol. 37 no. 3, pp. 336-339, DOI: 10.1016/j.gaitpost.2012.07.025, 2013.
[41] P. M. Carry, R. Gala, K. Worster, S. Kanai, N. H. Miller, D. James, A. J. Provance, J. J. Carollo, "Postural stability and kinetic change in subjects with patellofemoral pain after a nine-week hip and core strengthening intervention," International Journal of Sports Physical Therapy, vol. 12 no. 3, pp. 314-323, 2017.
[42] J. E. Willson, I. S. Davis, "Lower extremity mechanics of females with and without patellofemoral pain across activities with progressively greater task demands," Clinical biomechanics, vol. 23 no. 2, pp. 203-211, DOI: 10.1016/j.clinbiomech.2007.08.025, 2008.
[43] N. R. Heebner, D. M. Rafferty, M. F. Wohleber, A. J. Simonson, M. Lovalekar, A. Reinert, T. C. Sell, "Landing kinematics and kinetics at the knee during different landing tasks," Journal of Athletic Training, vol. 52 no. 12, pp. 1101-1108, DOI: 10.4085/1062-6050-52.11.25, 2017.
[44] J. T. Podraza, S. C. White, "Effect of knee flexion angle on ground reaction forces, knee moments and muscle co-contraction during an impact-like deceleration landing: implications for the non-contact mechanism of ACL injury," The Knee, vol. 17 no. 4, pp. 291-295, DOI: 10.1016/j.knee.2010.02.013, 2010.
[45] M. Walsh, M. C. Boling, M. McGrath, J. T. Blackburn, D. A. Padua, "Lower extremity muscle activation and knee flexion during a jump-landing task," Journal of Athletic Training, vol. 47 no. 4, pp. 406-413, DOI: 10.4085/1062-6050-47.4.17, 2012.
[46] T. Nagai, T. C. Sell, A. J. House, J. P. Abt, S. M. Lephart, "Knee proprioception and strength and landing kinematics during a single-leg stop-jump task," Journal of Athletic Training, vol. 48 no. 1, pp. 31-38, DOI: 10.4085/1062-6050-48.1.14, 2013.
[47] K. R. Pfile, J. M. Hart, D. C. Herman, J. Hertel, D. C. Kerrigan, C. D. Ingersoll, "Different exercise training interventions and drop-landing biomechanics in high school female athletes," Journal of Athletic Training, vol. 48 no. 4, pp. 450-462, DOI: 10.4085/1062-6050-48.4.06, 2013.
[48] C. -M. Fong, J. T. Blackburn, M. F. Norcross, M. McGrath, D. A. Padua, "Ankle-dorsiflexion range of motion and landing biomechanics," Journal of Athletic Training, vol. 46 no. 1,DOI: 10.4085/1062-6050-46.1.5, 2011.
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Abstract
Background. This study investigated the effects of lower limb movements on dynamic postural stability (DPS) during drop landing in adult women with patellofemoral pain syndrome (PFPS). Methods. Thirty-eight adult women were recruited and divided into two groups, the PFPS group and the control group. The study participants performed a single-leg drop landing from a 30 cm box, and their lower limb movements and DPS were measured. Differences between groups were examined using independent sample
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
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1 Department of Human Movement Science, Incheon National University, Incheon, Republic of Korea; Functional Rehabilitation Biomechanics Laboratory, Incheon National University, Incheon, Republic of Korea
2 Functional Rehabilitation Biomechanics Laboratory, Incheon National University, Incheon, Republic of Korea
3 Functional Rehabilitation Biomechanics Laboratory, Incheon National University, Incheon, Republic of Korea; Division of Sport Science, Incheon National University, Incheon, Republic of Korea; Sport Science Institute, Incheon National University, Incheon, Republic of Korea
4 Division of Sport Science, Incheon National University, Incheon, Republic of Korea; Sport Science Institute, Incheon National University, Incheon, Republic of Korea; Health Promotion Center, Incheon National University, Incheon, Republic of Korea
5 The Department of Mechatronics Engineering, Incheon National University, Incheon, Republic of Korea
6 Functional Rehabilitation Biomechanics Laboratory, Incheon National University, Incheon, Republic of Korea; Division of Sport Science, Incheon National University, Incheon, Republic of Korea; Sport Science Institute, Incheon National University, Incheon, Republic of Korea; Health Promotion Center, Incheon National University, Incheon, Republic of Korea