Proximal femoral canal shape is more accurately assessed on AP hip radiographs than AP pelvis radiographs in primary hip osteoarthritis

Accuracy of digital templating in uncemented primary total hip arthroplasty: which factors are associated with accuracy of preoperative planning?

BACKGROUND

Preoperative planning is a fundamental step for successful total hip arthroplasty (THA). Studies have highlighted the accuracy of preoperative digital templating for estimating acetabular cup and stem size. Stem design such as single-wedge metadiaphyseal (Type 1 stem) versus mid-short stem (microplasty) and surgical approach (anterior, direct lateral or posterior) have not been well investigated as predictors of THA templating accuracy.

METHODS

204 patients (220 hips) who had undergone elective THA between November 2016 and December 2019 and presented a saved preoperative template were retrospectively reviewed. Templates from 5 different surgeons were involved in the analysis. 3 different approaches were used: direct lateral (DL), posterior (PA), direct anterior (DAA). 2 different stem designs were used: single-wedge metadiaphyseal and single-wedge mid-short (Biomet Taperloc Microplasty), while the acetabular component remained the same. Bivariate and multivariate regression analyses were performed to determine predictors of accuracy.

RESULTS

Femoral component size templating accuracy was significantly improved when using the single-wedge mid-short stem (Taperloc Microplasty) design when performing bivariate analysis. Although accuracy of cup sizing was not affected by approach, precision was significantly better in the PA group (p < 0.05). Accuracy of templating was found to be independent of BMI and gender but dependent on presence of calibration marker and stem design (p < 0.05).

CONCLUSIONS

When striving for improved templating accuracy, acetabular and femoral component accuracy were best achieved using a calibration marker and a metaphyseal short femoral stem design.

Preoperative imaging of spinopelvic pathologies : State of the art

The field of musculoskeletal diagnostics and personalized medicine has undergone a revolutionary transformation due to a deeper understanding of skeletal biomechanics and due to technological advancements. Analogous to this transformation, our understanding of spinopelvic conditions has experienced a paradigm shift in terms of both static and dynamic changes in spinopelvic pathologies and enabled a more accurate delineation of the drivers of disability. The purpose of this review is to describe the standard and state of the art of preoperative diagnostic and planning methods for common spinopelvic pathologies and to discuss both the added clinical value and limitations. The rationale is to accelerate the accurate and timely diagnosis and as well as the efficient and safe preoperative workflow.

Varus will have varus; a radiological study to assess and predict varus stem placement in uncemented femoral stems

BACKGROUND

Varus inclination of the uncemented stem is not necessarily a technical error. The proximal femoral anatomy of hips with a coxa vara deformity frequently predisposes varus inclination.

METHODS

We reviewed a series of 200 patients undergoing primary uncemented THA with the Corail® hip system. Preoperative data were based on patient demographics, diagnosis, and radiographic information (preoperative templating-CT measurements), and compared postoperative alignment for each stem and type of stem used. Proximal femoral traits which can alert surgeons, when templating preoperatively, to potential varus alignment were noted.

RESULTS

All stems were inserted either in neutral or varus alignments. Low neck shaft angle is strongly predictive of increased varus stem alignment (p&lt;0.001). Stems inserted with higher varus alignment were associated with the preoperative morphological traits associated with coxa vara hip deformities - increased femoral offset (p&lt;0.001), greater trochanteric overhang (p&lt;0.001), greater trochanteric height (p&lt;0.046), and a lower canal flare index (p&lt;0.046).

CONCLUSIONS

Varus stem alignment is neither unexpected nor necessarily a technical failure when using this particular uncemented stem system. Coxa vara deformities, due to a combination of morphological traits, are more likely to be inserted with higher varus alignment than hips with normal or higher neck shaft angles. Surgeons need to be aware of this when carrying out preoperative templating and intraoperative assessment, in order to prevent over-compensation for offset, length or stability.