1. Lee SR, Ha YC, Kang H, Park YG, Nam KW, Kim SR. Morbidity and mortality in Jeju residents over 50-years of age with hip fracture with mean 6-year follow-up: a prospective cohort study. J Korean Med Sci 2013;28:1089–94.

2. Yoon HK, Park C, Jang S, Jang S, Lee YK, Ha YC. Incidence and mortality following hip fracture in Korea. J Korean Med Sci 2011;26:1087–92.

3. Choi HJ, Shin CS, Ha YC, Jang S, Jang S, Park C, et al. Burden of osteoporosis in adults in Korea: a national health insurance database study. J Bone Miner Metab 2012;30:54–8.

4. Ha YC, Kim TY, Lee A, Lee YK, Kim HY, Kim JH, et al. Current trends and future projections of hip fracture in South Korea using nationwide claims data. Osteoporos Int 2016;27:2603–9.

5. Muraki S, Akune T, Oka H, En-Yo Y, Yoshida M, Nakamura K, et al. Prevalence of falls and the association with knee osteoarthritis and lumbar spondylosis as well as knee and lower back pain in Japanese men and women. Arthritis Care Res (Hoboken) 2011;63:1425–31.

6. Muraki S, Akune T, Oka H, Ishimoto Y, Nagata K, Yoshida M, et al. Physical performance, bone and joint diseases, and incidence of falls in Japanese men and women: a longitudinal cohort study. Osteoporos Int 2013;24:459–66.

7. Harris I, Hatfield A, Donald G, Walton J. Outcome after intramedullary nailing of femoral shaft fractures. ANZ J Surg 2003;73:387–9.

8. Wolinsky PR, McCarty E, Shyr Y, Johnson K. Reamed intramedullary nailing of the femur: 551 cases. J Trauma 1999;46:392–9.

9. Braten M, Terjesen T, Rossvoll I. Femoral shaft fractures treated by intramedullary nailing: a follow-up study focusing on problems related to the method. Injury 1995;26:379–83.

10. Ostrum RF, Agarwal A, Lakatos R, Poka A. Prospective comparison of retrograde and antegrade femoral intramedullary nailing. J Orthop Trauma 2000;14:496–501.

11. Ricci WM, Bellabarba C, Evanoff B, Herscovici D, Di-Pasquale T, Sanders R. Retrograde versus antegrade nailing of femoral shaft fractures. J Orthop Trauma 2001;15:161–9.

12. Toms AD, Morgan-Jones RL, Spencer-Jones R. Intramedullary femoral nailing: removing the nail improves subjective outcome. Injury 2002;33:247–9.

13. Tornetta P 3rd, Tiburzi D. Antegrade or retrograde reamed femoral nailing: a prospective, randomised trial. J Bone Joint Surg Br 2000;82:652–4.

14. Christodoulou AG, Givissis P, Antonarakos PD, Petsatodis GE, Hatzokos I, Pournaras JD. Knee joint effusion following ipsilateral hip surgery. J Orthop Surg (Hong Kong) 2010;18:309–11.

15. Harato K, Yoshida H. Pseudogout at the knee joint will frequently occur after hip fracture and lead to the knee pain in the early postoperative period. J Orthop Surg Res 2015;10:4.

16. Pun WK, Chow SP, Chan KC, Ip FK, Leong JC. Effusions in the knee in elderly patients who were operated on for fracture of the hip. J Bone Joint Surg Am 1988;70:117–8.

17. Shahid MS, Murphy D, O’Donnell T, Ryan E, Kaliszer MM, Masterson E. A prospective study for evaluation of knee effusion after hip surgery. Ir Med J 2002;95:140–1.

18. Jensen JS. Classification of trochanteric fractures. Acta Orthop Scand 1980;51:803–10.

19. Andersen E, Jorgensen LG, Hededam LT. Evans’ classification of trochanteric fractures: an assessment of the interobserver and intraobserver reliability. Injury 1990;21:377–8.

20. Gehrchen PM, Nielsen JO, Olesen B. Poor reproducibility of Evans’ classification of the trochanteric fracture: assessment of 4 observers in 52 cases. Acta Orthop Scand 1993;64:71–2.

21. Ahn H, Court-Brown CM, McQueen MM, Schemitsch EH. The use of hospital registries in orthopaedic surgery. J Bone Joint Surg Am 2009;91 Suppl 3:68–72.

22. Meling T, Harboe K, Enoksen CH, Aarflot M, Arthursson AJ, Soreide K. How reliable and accurate is the AO/OTA comprehensive classification for adult long-bone fractures? J Trauma Acute Care Surg 2012;73:224–31.

23. Sonawane DV. Classifications of intertrochanteric fractures and their clinical importance. Trauma Int 2015;1:7–11. 24. Frandsen PA, Andersen E, Madsen F, Skjodt T. Garden’s classification of femoral neck fractures: an assessment of inter-observer variation. J Bone Joint Surg Br 1988;70:588–90.

25. Mears SC. Classification and surgical approaches to hip fractures for nonsurgeons. Clin Geriatr Med 2014;30:229–41.

26. Guss DA. Hip fracture presenting as isolated knee pain. Ann Emerg Med 1997;29:418–20.

27. Mitani S, Shimizu M, Abo M, Hagino H, Kurozawa Y. Risk factors for second hip fractures among elderly patients. J Orthop Sci 2010;15:192–7.

28. Omsland TK, Emaus N, Tell GS, Ahmed LA, Center JR, Nguyen ND, et al. Ten-year risk of second hip fracture: a NOREPOS study. Bone 2013;52:493–7.

29. Yamanashi A, Yamazaki K, Kanamori M, Mochizuki K, Okamoto S, Koide Y, et al. Assessment of risk factors for second hip fractures in Japanese elderly. Osteoporos Int 2005;16:1239–46.

30. Muraki S, Akune T, Ishimoto Y, Nagata K, Yoshida M, Tanaka S, et al. Risk factors for falls in a longitudinal population-based cohort study of Japanese men and women: the ROAD Study. Bone 2013;52:516–23.