Evaluating the Reliability of Kinotek: An AI-Driven 3D Motion Capture Tool for Weight-Bearing Ankle Dorsiflexion Assessment.
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Background: The range of motion (ROM) in ankle dorsiflexion during weight-bearing activities has important functional implications, including an elevated risk of injury when ROM is restricted. The integration of advanced digital technologies, particularly those utilizing artificial intelligence (AI), is becoming increasingly prevalent across professional domains. These tools have demonstrated effectiveness in enhancing diagnostic accuracy and improving patient outcomes in physical rehabilitation. This study aimed to assess the reliability of a portable 3D motion capture platform incorporating AI (Kinotek) compared to a standard plastic goniometer in evaluating weight-bearing ankle dorsiflexion ROM.
Methods: Twenty-four healthy participants (mean age: 29 ± 12 years; height: 172.7 ± 10.2 cm; weight: 70.3 ± 15 kg) were recruited. Each participant completed two test-retest trials of weight-bearing ankle dorsiflexion during a forward lunge. Intertrial reliability was evaluated using intraclass correlation coefficients (ICC(2, k)) with 95% confidence intervals (CI), comparing measurements obtained from the Kinotek system and the goniometer.
Results: The mean ± standard deviation (standard error of the mean) ROM values were 18.8 ± 6.67 (0.99) degrees for Kinotek and 14.61 ± 5.72 (0.86) degrees for the goniometer. The ICC (95% CI) values were 0.90 (0.82–0.94) for Kinotek and 0.79 (0.65–0.89) for the goniometer. The Pearson correlation coefficient (r) was 0.55.
Conclusion: The findings indicate that the Kinotek system demonstrates good-to-excellent reliability, whereas the goniometer exhibits moderate-to-good reliability in assessing weight-bearing ankle dorsiflexion ROM. The strong association observed supports the potential utility of AI-driven motion capture systems as reliable tools in both clinical and research contexts for evaluating weight-bearing ankle dorsiflexion.
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1. Almansoof HS, Nuhmani S, Muaidi Q. Role of ankle dorsiflexion in sports performance and injury risk: A narrative review. Electron J Gen Med. 2023;20(5):em521. doi:10.29333/ejgm/13412
2. Zunko H, Vauhnik R. Reliability of the weight-bearing ankle dorsiflexion range of motion measurement using a smartphone goniometer application. PeerJ. 2021;9:e11977. doi:10.7717/peerj.11977
3. Malloy P, Morgan A, Meinerz C, Geiser C, Kipp K. The association of dorsiflexion flexibility on knee kinematics and kinetics during a drop vertical jump in healthy female athletes. Knee Surg Sports Traumatol Arthrosc. 2015;23(12):3550-3555. doi:10.1007/s00167-014-3222-z
4. Taylor JB, Wright ES, Waxman JP, Schmitz RJ, Groves JD, Shultz SJ. Ankle dorsiflexion affects hip and knee biomechanics during landing. Sports Health. 2022;14(3):328-335. doi:10.1177/19417381211019683
5. He Y, Fekete G, Sun D, et al. Lower limb biomechanics during the topspin forehand in table tennis: A systemic review. Bioengineering (Basel). 2022;9(8):336. doi:10.3390/bioengineering9080336
6. Baumbach SF, Braunstein M, Seeliger F, et al. Ankle dorsiflexion: What is normal? Development of a decision pathway for diagnosing impaired ankle dorsiflexion and gastrocnemius tightness. Arch Orthop Trauma Surg. 2016;136(9):1203-1211. doi:10.1007/s00402-016-2513-x
7. Johanson M, Baer J, Hovermale H, Phouthavong P. Subtalar joint position during gastrocnemius stretching and ankle dorsiflexion range of motion. J Athl Train. 2008;43(2):172-178. doi:10.4085/1062-6050-43.2.172
8. Mahieu NN, Witvrouw E, Stevens V, Van Tiggelen D, Roget P. Intrinsic risk factors for the development of Achilles tendon overuse injury: A prospective study. Am J Sports Med. 2006;34(2):226-235. doi:10.1177/0363546505279918
9. Backman LJ, Danielson P. Low range of ankle dorsiflexion predisposes for patellar tendinopathy in junior elite basketball players: A 1-year prospective study. Am J Sports Med. 2011;39(12):2626-2633. doi:10.1177/0363546511420552
10. Pascual Huerta J. The effect of the gastrocnemius on the plantar fascia. Foot Ankle Clin. 2014;19(4):701-718. doi:10.1016/j.fcl.2014.08.011
11. Hassan KA, Youssef RSE, Mahmoud NF, Eltagy H, El-Desouky MA. The relationship between ankle dorsiflexion range of motion, frontal plane projection angle, and patellofemoral pain syndrome. Foot Ankle Surg. 2022;28(8):1427-1432. doi:10.1016/j.fas.2022.08.003
12. Piva SR, Goodnite EA, Childs JD. Strength around the hip and flexibility of soft tissues in individuals with and without patellofemoral pain syndrome. J Orthop Sports Phys Ther. 2005;35(12):793-801. doi:10.2519/jospt.2005.35.12.793
13. de la Motte SJ, Lisman P, Gribbin TC, et al. Systematic review of the association between physical fitness and musculoskeletal injury risk: Part 3—Flexibility, power, speed, balance, and agility. J Strength Cond Res. 2019;33(6):1723-1735. doi:10.1519/JSC.0000000000002382
14. Dinh NV, Freeman H, Granger J, et al. Calf stretching in non-weight bearing versus weight bearing. Int J Sports Med. 2011;32(3):205-210. doi:10.1055/s-0030-1268505
15. Moreno-Pérez V, Soler A, Ansa A, et al. Acute and chronic effects of competition on ankle dorsiflexion ROM in professional football players. Eur J Sport Sci. 2020;20(1):51-60.
16. Mourcou Q, Fleury A, Diot B, Franco C, Vuillerme N. Mobile phone-based joint angle measurement for functional assessment and rehabilitation of proprioception. Biomed Res Int. 2015;2015:328142. doi:10.1155/2015/328142
17. Teyhen DS, Shaffer SW, Butler RJ, et al. What risk factors are associated with musculoskeletal injury in US Army Rangers? A prospective prognostic study. Clin Orthop Relat Res. 2015;473(9):2948-2958. doi:10.1007/s11999-015-4342-6
18. Medina McKeon JM, Hoch MC. The Ankle-Joint Complex: A Kinesiologic Approach to Lateral Ankle Sprains. J Athl Train. 2019;54(6):589-602. doi:10.4085/1062-6050-472-17
19. Abdulmassih S, Phisitkul P, Femino JE, Amendola A. Triceps surae contracture: Implications for foot and ankle surgery. J Am Acad Orthop Surg. 2013;21(7):398-407. doi:10.5435/JAAOS-21-07-398
20. Aquino MRC, Resende RA, Kirkwood RN, et al. Spatial-temporal parameters, pelvic, and lower limb movements during gait in individuals with reduced passive ankle dorsiflexion. Gait Posture. 2022;93:32-38. doi:10.1016/j.gaitpost.2022.01.010
21. Howe LP. The acute effects of ankle mobilizations on lower extremity joint kinematics. J Bodyw Mov Ther. 2017;21(4):775-780. doi:10.1016/j.jbmt.2016.11.007
22. Lima YL, Ferreira VMLM, de Paula Lima PO, Bezerra MA, de Oliveira RR, Almeida GPL. The association of ankle dorsiflexion and dynamic knee valgus: A systematic review and meta-analysis. Phys Ther Sport. 2018;29:61-69. doi:10.1016/j.ptsp.2017.07.003
23. Nakagawa TH, Petersen RS. Relationship of hip and ankle range of motion, trunk muscle endurance with knee valgus and dynamic balance in males. Physiother Sport. 2018;34:174-179. doi:10.1016/j.ptsp.2018.10.006
24. Rabin A, Kozol Z, Spitzer E, Finestone A. Ankle dorsiflexion among healthy men with different qualities of lower extremity movement. J Athl Train. 2014;49(5):617-623. doi:10.4085/1062-6050-49.3.14
25. Macrum E, Bell DR, Boling M, Lewek M, Padua D. Effect of limiting ankle-dorsiflexion range of motion on lower extremity kinematics and muscle-activation patterns during a squat. J Sport Rehabil. 2012;21(2):144-150. doi:10.1123/jsr.21.2.144
26. Stanley LE, Harkey M, Luc-Harkey B, et al. Ankle dorsiflexion displacement is associated with hip and knee kinematics in females following anterior cruciate ligament reconstruction. Res Sports Med. 2019;27(1):21-33. doi:10.1080/15438627.2018.1502180
27. Rabin A, Portnoy S, Kozol Z. The association of ankle dorsiflexion range of motion with hip and knee kinematics during the lateral step-down test. J Orthop Sports Phys Ther. 2016;46(11):1002-1009. doi:10.2519/jospt.2016.6621
28. Witvrouw E, Lysens R, Bellemans J, Cambier D, Vanderstraeten G. Intrinsic risk factors for the development of anterior knee pain in an athletic population: A two-year prospective study. Am J Sports Med. 2000;28(4):480-489. doi:10.1177/03635465000280040701
29. Noehren B, Hamill J, Davis I. Prospective evidence for a hip etiology in patellofemoral pain. Med Sci Sports Exerc. 2013;45(6):1120-1124. doi:10.1249/MSS.0b013e31828249d2
30. Greiwe RM, Saifi C, Ahmad CS, Gardner MJ. Anatomy and biomechanics of patellar instability. Oper Tech Sports Med. 2015;23(1):2-9. doi:10.1053/j.otsm.2014.10.001
31. Aderem J, Louw QA. Biomechanical risk factors associated with iliotibial band syndrome in runners: A systematic review. BMC Musculoskelet Disord. 2015;16:356. doi:10.1186/s12891-015-0808-7
32. D’Antoni F, Russo F, Ambrosio L, et al. Artificial intelligence and computer-aided diagnosis in chronic low back pain: A systematic review. Int J Environ Res Public Health. 2022;19(10):5971. doi:10.3390/ijerph19105971
33. Loria K. What’s the impact of AI on physical therapy? How artificial intelligence can enhance physical therapist services—and when PTs should use caution. APTA Mag. 2023;15(11):34-42.
34. Furness J, Schram B, Cox AJ, et al. Reliability and concurrent validity of the iPhone® compass application to measure thoracic rotation range of motion in healthy participants. PeerJ. 2018;6:e4431. doi:10.7717/peerj.4431
35. Kolber MJ, Hanney WJ. The reliability and concurrent validity of shoulder mobility measurements using a digital inclinometer and goniometer: A technical report. Int J Sports Phys Ther. 2012;7(3):306-313
36. Pottorf OA, Lee DJ, Czujko PN. Reliability and concurrent validity of mobile health technology for patient self-monitoring in physical rehabilitation. Shoulder Elbow Surg Int. 2022;6(3):506-511. doi:10.1016/j.jseint.2022.02.002
37. Reid S, Egen B. The validity and reliability of DrGoniometer, a smartphone application for measuring forearm supination. J Hand Ther. 2019;32:110-117. doi:10.1016/j.jht.2018.03.003
38. Salamh PA, Kolber M. The reliability, minimal detectable change, and concurrent validity of a gravity-based bubble inclinometer and iPhone application for measuring standing lumbar lordosis. Physiother Theory Pract. 2014;1:2-7. doi:10.3109/09593985.2013.800174
39. Shin SH, Ro DH, Lee OS, Oh JH, Kim SH. Within-day reliability of shoulder range of motion measurement with a smartphone. Man Ther. 2012;17:298-304. doi:10.1016/j.math.2012.02.010
40. Tayfur I, Afacan MA. Reliability of smartphone measurements of vital parameters: A prospective study using a reference method. Am J Emerg Med. 2019;37:1527-1530. doi:10.1016/j.ajem.2019.03.021
41. Koo TK, Li MY. A guideline of selecting and reporting intraclass correlation coefficients for reliability research [Published correction appears in J Chiropr Med, 2017, 16(4), 346]. J Chiropr Med. 2016;15(2):155-163. doi:10.1016/j.jcm.2016.02.012
42. Bosco FA, Aguinis H, Singh K, et al. Correlational effect size benchmarks. J Appl Psychol. 2015;100(2):431-449. doi:10.1037/a0038047
43. Chen B, Wang W, Hu G, et al. Concurrent validity of a markerless motion capture system for the assessment of shoulder functional movement. Med Novel Technol Devices. 2022;15:100131. doi:10.1016/j.medntd.2022.100131
44. Lempereur M, Brochard S, Leboeuf F, Rémy-Néris O. Validity and reliability of 3D marker-based scapular motion analysis: A systematic review. J Biomech. 2014;47(10):2219-2230. doi:10.1016/j.jbiomech.2014.04.028
45. Konor MM, Morton S, Eckerson JM, Grindstaff TL. Reliability of three measures of ankle dorsiflexion range of motion. Int J Sports Phys Ther. 2012;7(3):279-287.
46. Kim PJ, Peace R, Mieras J, Thoms T, Freeman D, Page J. Interrater and intrarater reliability in the measurement of ankle joint dorsiflexion is independent of examiner experience and technique used. J Am Podiatr Med Assoc. 2011;101(5):407-414. doi:10.7547/1010407
47. Pottorf O, Vapne D, Ghigiarelli J, Haase K. Reliability and concurrent validity of a markerless, single camera, portable 3D motion capture system for assessment of glenohumeral mobility. Int J Sports Phys Ther. 2023;18(5):1176-1185.
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