Unexpected Repercussions of the COVID-19 Pandemic on Total Hip Arthroplasty with Cemented Hip Prosthesis versus Cementless Implants.

(1) Background: Total hip arthroplasty (THA) is one of the most common procedures used for adult hip reconstruction, employing mainly two types of prostheses: cemented (CHP) and cementless (CLHP). This study aims to analyze the impact of the COVID-19 pandemic on THA with CHP and CLHP, in terms of the benefit/cost ratio. (2) Methods: This article represents a retrospective analysis of the differences concerning the benefit/cost ratio between THA with the two types of prostheses in 2950 patients admitted for THA in the two orthopedic clinics of our hospital between 1 January 2015-1 March 2020 in comparison with 1005 THA subjects seen between 1 April 2020-31 December 2022. (3) Results: In the first period, THA with CHP was performed in 45.83% of cases, while CLHP was used in 54.16% of patients. During the COVID-19 period, CHP was inserted in 52% of THA patients, while the other 48% had CLHP inserted, with a hospitalization duration reduced by over 50% for both types of implants (p ˂ 0.001). (4) Conclusions: CHP offered good outcomes, with quicker mobilization, and shorter hospitalization duration, compared to CLHP, but optimization of the patients' management can be achieved mainly by reducing the length of hospitalization through an appropriate preoperative patient evaluation through a multidisciplinary approach, an aspect that was proven during the COVID-19 pandemic.

Standard and line-to-line cementation of a polished short hip stem: Long-term in vitro implant stability.

The current trend is toward shorter hip stems. While there is a general agreement on the need for a cement mantle thicker than 2 mm, some surgeons prefer line-to-line cementation, where the mantle has only the thickness provided by the cement-bone interdigitation. The aim of this study was to assess if a relatively short, polished hip stem designed for a standard cementation can also be cemented line-to-line without increasing the risk of long-term loosening. Composite femurs with specific open-cell foam to allow cement-bone interdigitation were used. A validated in-vitro biomechanical cyclic test replicating long-term physiological loading was applied to femurs where the same stem was implanted with the Standard-mantle (optimal stem size) and Line-to-line (same rasp, one-size larger stem). Implant-bone motions were measured during the test. Inducible micromotions never exceeded 10 µm for both implant types (differences statistically not-significant). Permanent migrations ranged 50-300 µm for both implant types (differences statistically not-significant). While in the standard-mantle specimens there was a pronounced trend toward stabilization, line-to-line had less tendency to stabilize. The cement cracks were observed after the test by means of dye penetrants: The line-to-line specimens included the same cracks of the standard-mantle (but in the line-to-line specimens they were longer), and some additional cracks. The micromotions and cement damage were consistent with those observed in-vitro and clinically for stable stems, confirming that none of the specimens became dramatically loose. However, it seems that for this relatively short polished stem, standard-mantle cementation is preferable, as it results in less micromotion and less cement cracking. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2736-2744, 2018.

Failure analysis of the cement mantle in total hip arthroplasty with an efficient probabilistic method.

Accurate prediction of long-term behaviour of cemented hip implants is very important not only for patient comfort but also for elimination of any revision operation due to failure of implants. Therefore, a more realistic computer model was generated and then used for both deterministic and probabilistic analyses of the hip implant in this study. The deterministic failure analysis was carried out for the most common failure states of the cement mantle. On the other hand, most of the design parameters of the cemented hip are inherently uncertain quantities. Therefore, the probabilistic failure analysis was also carried out considering the fatigue failure of the cement mantle since it is the most critical failure state. However, the probabilistic analysis generally requires large amount of time; thus, a response surface method proposed in this study was used to reduce the computation time for the analysis of the cemented hip implant. The results demonstrate that using an efficient probabilistic approach can significantly reduce the computation time for the failure probability of the cement from several hours to minutes. The results also show that even the deterministic failure analyses do not indicate any failure of the cement mantle with high safety factors, the probabilistic analysis predicts the failure probability of the cement mantle as 8%, which must be considered during the evaluation of the success of the cemented hip implants.