1. Cow-hitch fixation in fracture hemiarthroplasty
- Author
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Samy Bouaicha, Christian Gerber, Karl Wieser, Jon J.P. Warner, Lukas Ernstbrunner, Paul Borbas, Elias Bachmann, Florian Grubhofer, University of Zurich, and Grubhofer, Florian
- Subjects
Shoulder ,Shoulders ,610 Medicine & health ,Proximal humerus fracture ,Diseases of the musculoskeletal system ,2732 Orthopedics and Sports Medicine ,Greater tuberosity reattachment ,Medicine ,Cadaver study ,Orthopedics and Sports Medicine ,Displacement (orthopedic surgery) ,Lesser Tuberosity ,Cow Hitch Cerclage ,Fixation (histology) ,Orthopedic surgery ,business.industry ,Biomechanics ,Shoulder Arthroplasty ,2746 Surgery ,RC925-935 ,Fracture (geology) ,Lesser tuberosity reattachment ,Surgery ,10046 Balgrist University Hospital, Swiss Spinal Cord Injury Center ,Hemiarthroplasty ,business ,Cadaveric spasm ,Nuclear medicine ,RD701-811 ,Greater Tuberosity - Abstract
Background The treatment of complex proximal humerus fractures with hemiarthroplasty is associated with a high failure rate due to secondary displacement of the tuberosities. It was the aim of this in-vitro study to compare the mechanical stability of tuberosity reattachment obtained with the so-called “Cow-Hitch” (CH) cerclage compared with conventional tuberosity reattachment. Methods A 4-part proximal humerus fracture was created in 10 fresh-frozen, human cadaveric shoulders. The greater and lesser tuberosity were reattached to the hemiarthroplasty stem with in total 4 CH Cerclages in the Cow-Hitch group. The conventional technique—recommended for the tested implant—was used in the control group using 6 sutures. A total of 5000 loading cycles with forces of 350N were applied, while motion (in mm) of the tuberosities was recorded in 3 directions (anteroposterior = AP, mediolateral = ML, inferosuperior = IS) with a telecentric camera. Results After 5000 loading cycles, the CH group showed less fragment displacement (AP: 2.3 ± 2.3 mm, ML: 1.8 ± 0.9 mm, IS: 1.3 ± 0.5 mm) than the conventional group (AP: 9.8 ± 12.3 mm, ML: 5.5 ± 5.6 mm, IS: 4.5 ± 4.7 mm). The differences were not statistically significant (AP: P = .241; ML: P = .159; IS: P = .216). The lesser tuberosity fragment displacement in the CH group after 5000 cycles was less in the AP (2.3 ± 3.3 vs. 4.0 ± 2.8, P = .359) and IS (1.9 ± 1.2 vs. 3.1 ± 1.8; P = .189) directions but higher in the ML direction (7.2 ± 5.7 vs 6.3 ± 3.6, P = .963). Conclusions In-vitro, “Cow-Hitch” cerclage results in mean greater tuberosity displacements of 2 mm and reliably prevents displacements greater than 5 mm. In contrast, the conventional fixation technique yields unreliable, variable stability with low to complete displacement upon cyclical loading.
- Published
- 2021