Effect of Stem Positioning on Biomechanical Performance of a Novel Cementless Short-Stem Canine Total Hip Implant

2021 ◽  
Author(s):  
Natalie Jean Worden ◽  
Kristian J. Ash ◽  
Nathaniel R. Ordway ◽  
Mark Miller ◽  
Kenneth A. Mann ◽  
...  
Keyword(s):  
Femoral Neck ◽  
Ex Vivo ◽  
Peak Load ◽  
Relative Size ◽  
Peak Torque ◽  
Torsional Stiffness ◽  
Short Stem ◽  
Hip Implant ◽  
Total Hip ◽  
Implant Size

Abstract Objective The aim of this study was to evaluate the effect of stem positioning on the biomechanical performance of a novel, collared, short-stem total hip implant under compression and torsion ex vivo. Study Design Six canine cadaveric femurs were implanted with a collared short-stem femoral implant. Canal flare index (CFI), stem angle, absolute and relative cut heights and relative size were measured radiographically and used as independent variables. Biomechanical performance of the construct was evaluated using physiologic loading (loading) and supraphysiologic loading (failure) protocols. Results During loading protocols, compressive stiffness was influenced by absolute cut height (p = 0.018). During failure protocols, peak torque was influenced by CFI (p = 0.004) and craniocaudal relative size (p = 0.005). Peak load and torsional stiffness were not impacted by any of the radiographic variables (p > 0.05). Three of six femurs developed longitudinal fractures originating at the medial calcar at the time of failure. Conclusion The biomechanical performance of the collared short-stem implant was positively impacted by preserving more of the femoral neck, having a higher CFI and using a smaller implant size relative to the femoral neck isthmus.

Radiographic and Biomechanical Assessment of Three Implant Designs for Canine Cementless Total Hip Replacement

2020 ◽  
Vol 33 (06) ◽  
pp. 417-427
Author(s):  
Natalie J. Worden ◽  
Kristian J. Ash ◽  
Nathaniel R. Ordway ◽  
Mark A. Miller ◽  
Kenneth A. Mann ◽  
...  
Keyword(s):  
Peak Load ◽  
Biomechanical Testing ◽  
Peak Torque ◽  
Torsional Stiffness ◽  
Destructive Testing ◽  
Hip Implant ◽  
Total Hip ◽  
Biomechanical Assessment ◽  
Non Destructive

Abstract Objective The aim of this study was to evaluate the relationship between radiographic fit/fill measurements and biomechanical performance of three canine cementless total hip implant designs using an in vitro biomechanical testing protocol that replicates compression and torsion. Study Design Eighteen (six/group) canine cadaveric femurs were implanted with one of three cementless total hip implant designs: (1) collarless, (2) collared or (3) lateral bolt stems. Femoral length, canal flare index (CFI), canal fill, stem fit, stem level and stem angle were measured as independent variables. Biomechanical performance was tested using physiological, non-destructive gait loading (loading protocols) and destructive testing (failure protocols). Results During loading protocols, compressive stiffness was influenced by stem level (p < 0.05) and torsional stiffness was influenced by stem level and CFI for collarless stems (p < 0.05). During failure protocols, peak load was influenced by mediolateral (ML) stem angle (p < 0.05) and CFI (p < 0.01) for collarless stems and CFI for lateral bolt stems (p < 0.05). Peak torque was influenced by ML stem angle, craniocaudal stem angle and CFI for collarless stems (p < 0.05) and average ML fill for collared stems (p < 0.05). Conclusion Biomechanical performance of collarless stems in cementless hip arthroplasty is more impacted by radiographic fit/fill than lateral bolt and collared stems. As a result, collarless stems may be more dependent on preoperative fit and intraoperative precision.

scholarly journals Uncemented versus cemented arthroplasty after metal-on-metal total hip replacement in patients with femoral neck fractures: a retrospective study

2021 ◽  
Vol 49 (5) ◽  
pp. 030006052110122
Author(s):  
Wenlu Liu ◽  
Huanyi Lin ◽  
Xianshang Zeng ◽  
Meiji Chen ◽  
Weiwei Tang ◽  
...  
Keyword(s):  
Femoral Neck ◽  
Clinical Outcomes ◽  
Total Hip Replacement ◽  
Hip Replacement ◽  
Femoral Neck Fractures ◽  
Harris Hip Score ◽  
Complication Rates ◽  
Total Hip ◽  
Metal On Metal

Objective To compare the clinical outcomes of primary metal-on-metal total hip replacement (MoM-TR) converted to uncemented total hip replacement (UTR) or cemented total hip replacement (CTR) in patients with femoral neck fractures (AO/OTA: 31B/C). Methods Patient data of 234 UTR or CTR revisions after primary MoM-TR failure from March 2007 to January 2018 were retrospectively identified. Clinical outcomes, including the Harris hip score (HHS) and key orthopaedic complications, were collected at 3, 6, and 12 months following conversion and every 12 months thereafter. Results The mean follow-up was 84.12 (67–100) months for UTR and 84.23 (66–101) months for CTR. At the last follow-up, the HHS was better in the CTR- than UTR-treated patients. Noteworthy dissimilarities were correspondingly detected in the key orthopaedic complication rates (16.1% for CTR vs. 47.4% for UTR). Statistically significant differences in specific orthopaedic complications were also detected in the re-revision rate (10.3% for UTR vs. 2.5% for CTR), prosthesis loosening rate (16.3% for UTR vs. 5.9% for CTR), and periprosthetic fracture rate (12.0% for UTR vs. 4.2% for CTR). Conclusion In the setting of revision of failed primary MoM-TR, CTR may demonstrate advantages over UTR in improving functional outcomes and reducing key orthopaedic complications.

Effect of Induced Incomplete Ossification of the Humeral Condyle on Ex Vivo Humeral Condylar Biomechanics

2020 ◽  
Author(s):  
Logan M. Scheuermann ◽  
Michael G. Conzemius
Keyword(s):  
Mechanical Testing ◽  
Study Design ◽  
Ex Vivo ◽  
Peak Load ◽  
Testing System ◽  
Condylar Fracture ◽  
Naturally Occurring ◽  
Left And Right ◽  
Condylar Fractures ◽  
Humeral Condyle

Abstract Objective The aim of this study was to investigate the effects of an induced incomplete ossification of the humeral condyle (IOHC) lesion on ex vivo canine humeral condylar biomechanics. Study Design Nine paired cadaveric elbows were collected from mature dogs weighing between 20 and 25 kg. Left and right limbs were randomized to IOHC or normal groups. Limbs were prepared for mechanical testing; ligaments were preserved and an IOHC lesion was created. Elbows were potted, positioned into a biomaterials testing system at an angle of 135 degrees and axially loaded to failure at a rate of 30 mm/minute. Results Induced IOHC lesions reduced peak load (p = 0.02) when compared with an intact humerus. There was no difference between stiffness (p = 0.36) of intact humeri or humeri with an induced IOHC lesion. An induced IOHC lesion increased (p = 0.012) the probability of intracondylar fracture under load. Conclusion Cadaveric humeri are weakened by the creation of an intracondylar osteotomy and fractures secondary to induced IOHC are similar to spontaneous humeral condylar fractures. These findings support the hypothesis that naturally occurring IOHC weakens the humeral condyle and may predispose to humeral condylar fracture.

scholarly journals Implications of component size and calibration error on digital templating for total hip arthroplasty. A visual matrix from a simple mathematical model

2021 ◽  
Author(s):  
Christoph Kolja Boese ◽  
Tim Rolvien ◽  
Matthias Trost ◽  
Michael Frink ◽  
Jan Hubert ◽  
...  
Keyword(s):  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Standard Procedure ◽  
Calibration Error ◽  
Optimal Size ◽  
Linear Calibration ◽  
Component Size ◽  
Digital Templating ◽  
Total Hip ◽  
Implant Size

Abstract Objective Preoperative digital templating is a standard procedure in total hip arthroplasty. Deviations between template size and final implant size may result from inaccurate calibration, templating as well as intraoperative decisions. So far, the explicit effect of calibration errors on templating has not been addressed adequately. Materials and Methods A mathematical simulation of calibration errors up to ± 24% was applied to the templating of acetabular cups (38 to 72 mm diameter). The effect of calibration errors on template component size as deviation from optimal size was calculated. Results The relationship between calibration error and component size deviation is inverse and linear. Calibration errors have a more pronounced effect on larger component sizes. Calibration errors of 2–6% result in templating errors of up to two component sizes. Common errors of up to 12% may result in templating errors of 3–4 sizes for common implant sizes. A tabular matrix visualizes the effect. Conclusion Calibration errors play a significant role in component size selection during digital templating. Orthopedic surgeons should be aware of this effect and try to identify and address this source of error.

scholarly journals Abductor Muscle Force after Straight-Stem Compared to Short-Stem Total Hip Arthroplasty through a Modified Direct Lateral Approach: Functional Assessment of 70 Consecutive Patients of a Randomized Controlled Clinical Trial

2021 ◽  
Vol 10 (6) ◽  
pp. 1235
Author(s):  
Michael Fuchs ◽  
Marie-Anne Hein ◽  
Martin Faschingbauer ◽  
Mirco Sgroi ◽  
Ralf Bieger ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Muscle Strength ◽  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Lateral Approach ◽  
Short Stem ◽  
Abductor Muscle ◽  
Total Hip ◽  
Straight Stem ◽  
Direct Lateral Approach

Because of preservation of proximal femoral bone stock and minimized soft tissue trauma, short-stem implants are becoming increasingly important in total hip arthroplasty (THA). The postulated advantage regarding the functional outcome has not been verified. We hypothesized an increased abductor muscle strength by the use of a short-stem design. Seventy consecutive patients of a randomized clinical trial were included. Of these, 67 patients met the inclusion criteria after 12 months. Thirty-five patients received a standard straight stem and 32 patients a short-stem femoral component. All surgeries were performed by a modified direct lateral approach. Isometric muscle strength of the hip abductors was evaluated preoperatively 3 and 12 months after surgery. Harris hip score (HHS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were evaluated. After three months, there were no differences between the two groups; the abductor force was comparable to the preoperative initial values. After 12 months, a significant increase in muscle strength for the short stem patient group compared to preoperative baseline values was measured (straight-stem THA, 0.09 Nm/kg ± 0.4, p = 0.32; short-stem THA, 0.2 Nm/kg ± 0.3, p = 0.004). Comparison of the 12-month postoperative total HHS and WOMAC revealed no significant differences between both groups. A significant increase in hip abductor muscle strength 12 months after short-stem THA compared to conventional-stem THA was observed.

scholarly journals Short-stem total hip arthroplasty is not associated with an earlier return to work compared to a straight-stem design

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Georg Hauer ◽  
Maria Smolle ◽  
Sabrina Zaussinger ◽  
Joerg Friesenbichler ◽  
Andreas Leithner ◽  
...  
Keyword(s):  
Total Hip Arthroplasty ◽  
Sick Leave ◽  
Return To Work ◽  
Hip Arthroplasty ◽  
Short Stem ◽  
Multivariate Linear Regression Analysis ◽  
Stem Design ◽  
Total Hip ◽  
Straight Stem ◽  
Significant Difference

AbstractReturn to work (RTW) has been specifically identified as a high priority in patients undergoing total hip arthroplasty (THA). This investigation sought to assess the effect of the stem design on patients’ RTW. Secondly, the study aimed to identify risk factors that lead to a delayed RTW. Questionnaires inquiring about RTW, employment history, educational level, type of work, physical demands and joint awareness were administered by post. Further data were collected from patients’ hospital records. 176 patients who underwent THA using a short-stem and 97 patients using a straight-stem design were compared. The median return to work time was 10 weeks [IQR 7–14 weeks], with no significant difference between the two groups (short stems vs. straight stems; 10 [IQR 7–14] vs. 11 [7.5–13.5] weeks; p = 0.693). In the multivariate linear regression analysis, self-employment vs. employee (p = 0.001), dimension of preoperative workload (p = 0.001), preoperative sick leave (p < 0.001), and hospital length of stay (LOS) (p < 0.001) independently affected the period until work was resumed. The Forgotten-Joint-Score-12 showed no significant difference between the two groups. The data show that the majority of THA patients can expect to resume work and stem design has no impact on RTW. Employees with preoperative sick leave, prolonged hospital LOS and low workload are at higher risk for a delayed RTW.

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