Biomechanical Investigation of an Integrated 2-Screw Cephalomedullary Nail Versus a Sliding Hip Screw in Unstable Intertrochanteric Fractures

Abstract

Objective: To compare the efficacy of 2 intertrochanteric (IT) fracture fixation devices in conferring mechanical stability to unstable IT femur fractures. Methods: Nine pairs of cadaveric female femurs with a groupwise average bone quality indicative of osteopenia were used. An unstable IT fracture without calcar support (OTA/AO 31-A2) was created and stabilized with either a sliding hip screw and side plate (SHS) or a cephalomedullary nail using an integrated dual-screw fixation [InterTAN (ITN)]. Constructs were evaluated under stepwise and increasing cyclic loading up to 50,000 cycles (1500 N) or by failure in a test model that may best simulate hip joint contact forces at heel strike. Number of cycles to failure, failure load, and femoral head rotation about the screw axis were compared between groups. Results: The average number of cycles in the ITN group was greater compared with that in the SHS group (48,383 vs. 31,403 cycles, P = 0.046). Similarly, the average maximum load survived by the ITN group was greater than that of the SHS group (1456 vs. 1113 N, P = 0.046). The number of constructs that survived up to the maximum applied load of 1500 N was greater in the ITN group (8/9, 89%) when compared with that of the SHS constructs (3/9, 33%) (P = 0.049). Finally, the ITN group conferred greater rotational control of the femoral head compared with the SHS constructs (1.5 vs. 5.5 degrees, P = 0.018), and reduced the amount of varus collapse (11.1 vs. 31.1 degrees, P = 0.038). Conclusions: The integrated dual-screw construct appeared to confer significantly greater fracture stability compared with a sliding hip screw and side plate using a worst-case model that simulates heel strike during gait. Study data provide biomechanical evidence that the ITN device may provide more stability and rotational resistance than a sliding hip screw in the elderly female patient population with an unstable IT fracture and compromised bone quality.

Intramedullary nail versus sliding hip screw for stable and unstable trochanteric and subtrochanteric fractures

“…recent studies have been unable to demonstrate any significant differences in outcome, 5,6 whereas others report a beneficial effect of IMNs in the treatment of unstable trochanteric and subtrochanteric fractures. 7 Flowchart of the study population. ASA, American Society of Anesthesiologists; IMN, intramedullary nail; NHFR, Norwegian Hip Fracture Register; PROM, patient-reported outcome measure; SHS, sliding hip screw.…”

The utility of routine dual-energy x-ray absorptiometry scans in matched-pair cadaveric biomechanical trauma research

“…Ten articles spanning February 2013 to February 2019 were identified, with a summary of findings listed in Table 1. [10][11][12][13][14][15][16][17][18][19] In those 10 articles, there were 113 reported matched pairs used with DEXA scans. Seven out of the 10 studies performed DEXA scans on the proximal femur, two performed scans on the humerus, and one performed scans on the calcaneus.…”

Benefit of lag screw placement by a single- or two-screw nailing system in elderly patients with AO/OTA 31-A2 trochanteric fractures

“…25 Scientific biomechanical proof for the rotational stability of INTERTAN nails has been established. 26 This nail offers an integrated interlocking screw option to increase stability, reduce rotational movement of the femoral head, eliminate excessive sliding, and greatly reduce the possibility of the Z-effect. 27,28 The Gamma3 system features an anti-rotation screw and head-neck lag screw, which promotes fracture healing by dynamically compressing the fracture segments and thus effectively improving the rotational stability of head-neck fractures.…”