Biomechanical and clinical assessment of dissociation in bipolar hip hemiarthroplasty.
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| Title: | Biomechanical and clinical assessment of dissociation in bipolar hip hemiarthroplasty. |
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| Authors: | Ozan, Fırat1 (AUTHOR) firat.ozan@sbu.edu.tr, Okur, Kürşat Tuğrul1 (AUTHOR), Mavi, Fırat2 (AUTHOR), Pekedis, Mahmut2 (AUTHOR) |
| Source: | Bio-Medical Materials & Engineering. May2025, Vol. 36 Issue 3, p185-199. 15p. |
| Subjects: | Hip joint dislocation, Shear strain, Reoperation, Hemiarthroplasty, Polyethylene |
| Abstract: | Background: Dissociation is a special type of dislocation that is rarely seen in bipolar hemiarthroplasty. Objectıve: To investigate the clinical and biomechanical causes of dissociative dislocation of acetabular cup components in the hips of patients after bipolar hemiarthroplasty (BHA). Methods: BHA heads were divided into three groups according to their design. Cam-out and pull-out biomechanical tests were conducted to investigate the separation strengths of the BHA heads. Results: Among the 1684 BHA surgeries performed, the revision surgery rate was 4% (68 hips) and dissociation rate was 0.8% (15 hips). According to the cam-out test result, the highest values in the parameters ultimate force (Fmax) ultimate torque (T), vertical displacement at maximum force (δm), rotation at maximum force (ϕm), maximum principal strain (Ɛmax), minimum principal strain (Ɛmin), average normal strain (Ɛav), maximum shear strain (γmax), uniaxial normal strain (Ɛun) were detected in Type 2 BHA head. The pull-out values of the implants were sufficient to prevent the distraction force that may occur on the implant due to manual traction applied to the hip dislocations. However, in closed reduction maneuvers, cam-out-shaped deformation forces may cause dissociation in Types 1 and 3, but not in Type 2 BHA heads. According to the pull-out test results, while high values were detected in the parameters Fmax and stiffness (k) in the Type 2 BHA head, δm and maximum force (E) parameters were found to be high in the Type 1 BHA head. In the cam-out test, a strong positive relationship was found between the thickness and width of the polyethylene locking ring and Fmax, T, δm, ϕm, Ɛmax, γmax, Ɛun. Conclusıon: Better BHA head designs and polyethylene designs may help resolve the rare problem of dissociation, which almost always leads to resurgical procedures. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Background: Dissociation is a special type of dislocation that is rarely seen in bipolar hemiarthroplasty. Objectıve: To investigate the clinical and biomechanical causes of dissociative dislocation of acetabular cup components in the hips of patients after bipolar hemiarthroplasty (BHA). Methods: BHA heads were divided into three groups according to their design. Cam-out and pull-out biomechanical tests were conducted to investigate the separation strengths of the BHA heads. Results: Among the 1684 BHA surgeries performed, the revision surgery rate was 4% (68 hips) and dissociation rate was 0.8% (15 hips). According to the cam-out test result, the highest values in the parameters ultimate force (Fmax) ultimate torque (T), vertical displacement at maximum force (δm), rotation at maximum force (ϕm), maximum principal strain (Ɛmax), minimum principal strain (Ɛmin), average normal strain (Ɛav), maximum shear strain (γmax), uniaxial normal strain (Ɛun) were detected in Type 2 BHA head. The pull-out values of the implants were sufficient to prevent the distraction force that may occur on the implant due to manual traction applied to the hip dislocations. However, in closed reduction maneuvers, cam-out-shaped deformation forces may cause dissociation in Types 1 and 3, but not in Type 2 BHA heads. According to the pull-out test results, while high values were detected in the parameters Fmax and stiffness (k) in the Type 2 BHA head, δm and maximum force (E) parameters were found to be high in the Type 1 BHA head. In the cam-out test, a strong positive relationship was found between the thickness and width of the polyethylene locking ring and Fmax, T, δm, ϕm, Ɛmax, γmax, Ɛun. Conclusıon: Better BHA head designs and polyethylene designs may help resolve the rare problem of dissociation, which almost always leads to resurgical procedures. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 09592989 |
| DOI: | 10.1177/09592989241306688 |
