{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,27]],"date-time":"2026-10-27T10:09:24Z","timestamp":1793095764302,"version":"4.5.0"},"reference-count":43,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2025,9,15]],"date-time":"2025-09-15T00:00:00Z","timestamp":1757894400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"Korean government (Ministry of Science and ICT, MSIT)","doi-asserted-by":"publisher","award":["2018R1C1B5084552"],"award-info":[{"award-number":["2018R1C1B5084552"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background\/Objectives: The combined effect of femoral neck\u2013shaft angle and lag screw position on unstable intertrochanteric fracture fixation has not been well established. This biomechanical study evaluated the effects of two caput\u2013collum\u2013diaphyseal (CCD) angles and two lag screw positions on construct stability. Methods: Twenty-four synthetic femurs with identical AO\/OTA 31-A2.2 fracture gaps (2 mm) were fixed using cephalomedullary nails with CCD angles of either 125\u00b0 or 130\u00b0, each with a central or inferior (calcar) lag screw (n = 6\/group). Constructs were tested in a single-leg stance under preloading, cyclic loading (75\u2013750 N, 10,000 cycles, and 2 Hz), and axial loading to failure. Lag screw migration was measured radiographically, and femoral head rotation was recorded using a three-dimensional coordinate-measuring device. Stiffness, failure load, and rotations were compared using the Kruskal\u2013Wallis and Bonferroni post hoc tests. Results: The 125\u00b0 inferior configuration showed the highest stiffness (188 \u00b1 15 N\/mm, p = 0.038) and failure load (1350 \u00b1 97 N, p = 0.047), with the least screw migration (0.54 \u00b1 0.11 mm, p = 0.003), significantly outperforming the 125\u00b0 central and 130\u00b0 central constructs. However, it exhibited greater varus collapse (2.25 \u00b1 0.27\u00b0, p = 0.013) and axial rotation (~20\u201330% higher than others, p = 0.025). Screw position had a stronger effect on stability than the CCD angle, although the 130\u00b0 inferior construct showed slightly less varus deformation. Conclusions: An inferior calcar-guided lag screw improves fixation strength and stiffness in unstable intertrochanteric fractures, particularly in those with a 125\u00b0 nail. However, this configuration increases varus and rotational displacement, warranting adjunct measures to enhance rotational control in clinical applications.<\/jats:p>","DOI":"10.3390\/jcm14186495","type":"journal-article","created":{"date-parts":[[2025,9,16]],"date-time":"2025-09-16T07:33:02Z","timestamp":1758007982000},"page":"6495","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Biomechanical Analysis of Fixation Strength in Unstable Intertrochanteric Femoral Fracture Models Based on the Caput\u2013Collum\u2013Diaphyseal Angle of Cephalomedullary Nails and Position of Lag Screws"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4137-0764","authenticated-orcid":false,"given":"Yong-Cheol","family":"Yoon","sequence":"first","affiliation":[{"name":"Orthopedic Trauma Division, Trauma Center, Gachon University College of Medicine, Namdong-gu, Incheon 21565, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sung-Jae","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, Inje University, Gimhae 50834, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5486-2560","authenticated-orcid":false,"given":"Hyung Keun","family":"Song","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Ajou University School of Medicine, Yeongtong-gu, Suwon 16499, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1007\/BF01623184","article-title":"Hip fractures in the elderly: A world-wide projection","volume":"2","author":"Cooper","year":"1992","journal-title":"Osteoporos. 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