Introduction:

Classification

![Explosion views of various types of hip arthroplasty. Upper left: The native hip joint possesses an articular surface on both the acetabulum and femoral head. Upper middle and right: Hemiarthroplasty entails the replacement of the original femoral head and neck with an artificial implant while leaving the native acetabular cartilage untouched. The distinction between unipolar and bipolar hemiarthroplasty comes down to the presence of an additional articulation inside the spherical component. Lower right: Conversely, THA involves the substitution of both the femoral and acetabular surfaces with artificial prostheses. Note that the acetabular cartilage remains intact in hemiarthroplasty but is removed to induce cup fixation in THA. Lower right: In THA, a constrained liner features a locking ring that secures the artificial femoral head in place while still permitting rotation. Lower left: In hip resurfacing, only the articular surface on both the acetabulum and femoral head is replaced.

Park S, Yun JS, Bang D-H, Jung Y, Kwack K-S, Kim J-T. Deviation of Latitude Cut: A Simple Sign to Differentiate Total Hip Arthroplasty from Hemiarthroplasty in Radiography. Journal of Clinical Medicine. 2023; 12(19):6218. https://doi.org/10.3390/jcm12196218](attachment:958dd8cf-5dc0-4904-be2a-b4ed5356a8a5:jcm-12-06218-g001.png)

Explosion views of various types of hip arthroplasty. Upper left: The native hip joint possesses an articular surface on both the acetabulum and femoral head. Upper middle and right: Hemiarthroplasty entails the replacement of the original femoral head and neck with an artificial implant while leaving the native acetabular cartilage untouched. The distinction between unipolar and bipolar hemiarthroplasty comes down to the presence of an additional articulation inside the spherical component. Lower right: Conversely, THA involves the substitution of both the femoral and acetabular surfaces with artificial prostheses. Note that the acetabular cartilage remains intact in hemiarthroplasty but is removed to induce cup fixation in THA. Lower right: In THA, a constrained liner features a locking ring that secures the artificial femoral head in place while still permitting rotation. Lower left: In hip resurfacing, only the articular surface on both the acetabulum and femoral head is replaced.

![Cross-sections illustrating the relationship between components in various types of hip arthroplasty. The outline color represents the boundaries of components mechanically constrained within the construct. Green indicates a mechanically linked construct to the pelvis, whereas orange indicates a mechanically linked construct to the femur. Upper left: The concave acetabulum articulates with the spherical femoral head to form the native hip joint. Upper middle: The constrained liner comprehensively encases the artificial femoral head, allowing only rotation and preventing displacement, resulting in an axially linked state. Upper right, lower left and middle: In contrast, both THA and hemiarthroplasty leave one articulation unconstrained, allowing for displacement. Lower right: If the cup of the hemiarthroplasty does not adequately encompass the artificial femoral head, resulting in two unconstrained articulating interfaces, the cup–liner construct remains an unstable segment without constraint to either the pelvis or femur.

Park S, Yun JS, Bang D-H, Jung Y, Kwack K-S, Kim J-T. Deviation of Latitude Cut: A Simple Sign to Differentiate Total Hip Arthroplasty from Hemiarthroplasty in Radiography. Journal of Clinical Medicine. 2023; 12(19):6218. https://doi.org/10.3390/jcm12196218](attachment:83648033-3311-4a22-b742-e4712510c80d:jcm-12-06218-g005.png)

Cross-sections illustrating the relationship between components in various types of hip arthroplasty. The outline color represents the boundaries of components mechanically constrained within the construct. Green indicates a mechanically linked construct to the pelvis, whereas orange indicates a mechanically linked construct to the femur. Upper left: The concave acetabulum articulates with the spherical femoral head to form the native hip joint. Upper middle: The constrained liner comprehensively encases the artificial femoral head, allowing only rotation and preventing displacement, resulting in an axially linked state. Upper right, lower left and middle: In contrast, both THA and hemiarthroplasty leave one articulation unconstrained, allowing for displacement. Lower right: If the cup of the hemiarthroplasty does not adequately encompass the artificial femoral head, resulting in two unconstrained articulating interfaces, the cup–liner construct remains an unstable segment without constraint to either the pelvis or femur.

Radiology

https://radiologyassistant.nl/musculoskeletal/hip/arthroplasty

https://doi.org/10.2214/AJR.12.8843

https://doi.org/10.2214/AJR.12.8844

https://doi.org/10.1016/j.ejrad.2011.03.103

MR imaging:

https://doi.org/10.1148/rg.344140010

Pre-operative imaging

https://doi.org/10.3390/jcm11185465