Imaging in Hip Arthroplasty Management-Part 1: Templating: Past, Present and Future

Optimizing Acetabular Positioning: A Comprehensive Review of Contemporary Strategies in Total Hip Arthroplasty

Total hip arthroplasty (THA) is a widely practiced surgical intervention to alleviate pain and reinstate functionality in individuals afflicted with hip joint pathology. The positioning of the acetabulum assumes paramount significance in determining the efficacy of THA, exerting profound influences on biomechanical dynamics, stability, and the durability of outcomes over time. This comprehensive review meticulously evaluates contemporary methodologies for optimizing acetabular positioning in THA, encompassing advanced technologies such as computer-assisted navigation systems, patient-specific instrumentation, robotic-assisted surgical approaches, image-based planning techniques, and intraoperative fluoroscopy. Crucially, key discoveries underscore the pivotal role of precise acetabular alignment in mitigating complications such as dislocation, component wear, and impingement. Moreover, the implications for clinical practice accentuate the imperative of continuous education and training to ensure effective deployment of sophisticated methodologies. Recommendations for furthering research and enhancing practice development underscore the necessity of scrutinizing long-term prognoses, assessing cost-effectiveness, and embracing technological innovations perpetually refining THA outcomes. Collaborative endeavors among researchers, practitioners, and industry stakeholders emerge as indispensable drivers of advancement in this domain, fostering an environment conducive to elevating the standard of care for individuals undergoing THA.

Medullary-Sparing Antibiotic Cement Articulating Spacer Reduces the Rate of Mechanical Complications in Advanced Septic Hip Arthritis: A Retrospective Cohort Study

Antibiotic cement articulating spacers eradicate infection during a two-stage revision for advanced septic hip arthritis (ASHA); however, mechanical complications have been reported. We hypothesized that the rate of mechanical complications would be lower in medullary-sparing (MS) than in non-medullary-sparing (n-MS) articulating spacers. A retrospective study of ASHA using n-MS or MS spacers was conducted between 1999 and 2019. The rate of mechanical complications and reoperation and risk factors for mechanical complications were analyzed. The cohort included 71 n-MS and 36 MS spacers. All patients were followed up for 2 years. The rate of spacer dislocation was lower in MS (0%) than in n-MS spacers (14.1%; p = 0.014). The reoperation rate for mechanical complications was lower in MS (0%) than in n-MS spacers (12.7%; p = 0.019). The rate of a diaphyseal stem during reimplantation was lower in MS (0%) than in n-MS spacers (19.4%; p = 0.002). The identified risk factors for n-MS spacer dislocation were postoperative under-restored femoral head diameter ≥3 mm, femoral offset ≥3 mm, and surgical volume (≤6 resection arthroplasties per year). Both spacers controlled infection. However, MS spacers had a lower spacer dislocation and reoperation rate and avoided the diaphyseal stem during reimplantation. We recommend using MS spacers to restore native femoral head diameter and femoral offset when ASHA is treated by surgeons with lower surgical volumes.

A Standardised Protocol for Pre-operative Pelvic Radiographs for Templating in Total Hip Arthroplasty

PURPOSE

Digital templating using pre-operative radiographs enables pre-operative planning for total hip arthroplasty (THA). This allows surgeons to reproduce hip biomechanics effectively, reducing the risk of post-operative complications. Pelvic radiographs demonstrating the head, neck, trochanters, and proximal one-third of the femoral shaft allow calculation of key measurements including femoral offset and limb length discrepancy (LLD). Currently, no standardised guideline exists for obtaining pre-operative radiographs for templating in THA.  Materials and methods: A single-blinded retrospective cohort study assessing the quality of pre- and post-operative radiographs of 195 patients who underwent elective THA for osteoarthritis over a two-year period was performed. Quality was rated as good, fair or poor, respectively, depending upon whether ≥2, 1 or none of the following were met: Pubic symphysis (PS) and coccyx in a straight line with 1-3 cm between the superior edge of the PS and tip of coccyx, trochanters distinguishable, obturator rings symmetric. Post-operative images were assessed to determine whether the distal end of the implanted prosthesis was visible.  Results: The sample consisted of 195 patients. Pre-operatively 115 (59%) radiographs were classified as good, 71 (36.4%) fair and 9 (4.6%) poor. Post-operatively 46 (23.6%) were classified as good, 114 (58.4%) as fair and 30 (15.4%) as poor. In the post-operative radiographs, 25.6% did not include the distal tip of the prosthesis.  Conclusion: This study highlights significant scope to improve the quality of pre-operative radiographs, allowing accurate templating to optimise outcomes for THA. A protocol is recommended whereby the pelvic radiograph is centred on the PS at the lesser trochanter level, ensuring adequate exposure of the proximal femur, acetabulum and iliac crests.

Effects of Puerarin-Loaded Tetrahedral Framework Nucleic Acids on Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is recognized as a common refractory orthopedic disease that causes severe pain and poor quality of life in patients. Puerarin (Pue), a natural isoflavone glycoside, can promote osteogenesis and inhibit apoptosis of bone mesenchymal stem cells (BMSCs), demonstrating its great potential in the treatment of osteonecrosis. However, its low aqueous solubility, fast degradation in vivo, and inadequate bioavailability, limit its clinical application and therapeutic efficacy. Tetrahedral framework nucleic acids (tFNAs) are promising novel DNA nanomaterials in drug delivery. In this study, tFNAs as Pue carriers is used and synthesized a tFNA/Pue complex (TPC) that exhibited better stability, biocompatibility, and tissue utilization than free Pue. A dexamethasone (DEX)-treated BMSC model in vitro and a methylprednisolone (MPS)-induced ONFH model in vivo is also established, to explore the regulatory effects of TPC on osteogenesis and apoptosis of BMSCs. This findings showed that TPC can restore osteogenesis dysfunction and attenuated BMSC apoptosis induced by high-dose glucocorticoids (GCs) through the hedgehog and Akt/Bcl-2 pathways, contributing to the prevention of GC-induced ONFH in rats. Thus, TPC is a promising drug for the treatment of ONFH and other osteogenesis-related diseases.

A Comparison of Radiographic Outcomes after Total Hip Arthroplasty between the Direct Lateral Approach and Posterior Lateral Approach with EOS 2D/3D X-Ray Imaging System

OBJECTIVE

The classical approaches for total hip arthroplasty (THA) are the direct lateral approach (DLA) and posterior lateral approach (PLA). There are few studies comparing implant orientation with these two approaches, and the impact of surgical approaches on implant orientation remains controversial. With the rise of the EOS imaging system, we aimed to use it to identify the differences between and factors associated with implant orientation after THA using DLA and PLA.

METHODS

In our department from January 2019 to December 2021, 321 primary unilateral THAs that used PLA and DLA were enrolled. A total of 201 patients who received PLA and 120 patients who received DLA were included in this study. Two blinded observers measured each case using EOS imaging data. Postoperative imaging metrics and other relevant influencing factors of the two surgical approaches were compared. Postoperative imaging metrics, including the anteversion and inclination of the cup, anteversion of the stem, and combined anteversion were measured based on EOS. Other relevant influencing factors included age, approach, gender, laterality, BMI, anterior pelvic plane inclination, femoral head diameter, femoral offset, lateral pelvic tilt, pelvic incidence, pelvis axial rotation, sacral slope, sagittal pelvic tilt, and surgery time. Multiple linear regression analyses were performed to identify the predictors of acceptability for each imaging data point.

RESULTS

No dislocation was found in the 321 patients who underwent primary THA during this period. The mean anteversion and combined anteversion of the cups using the DLA were 21.33° ± 17.31° (-51.7°-60.8°) and 33.71° ± 20.85° (-38.8°-77.6°) and PLA were 25.34° ± 12.76° (-5.5°-57.0°) and 42.37° ± 18.85° (-8.7°-84.7°), respectively. The DLA group had smaller anteversion (p = 0.038) and combined anteversion (p < 0.001). We found that surgical approach (p < 0.05), anterior pelvic plane inclination (p < 0.001), gender (p < 0.001), and femoral head diameter (p < 0.001) were important factors affecting acetabular cup anteversion (R2  = 0.375) and combined anteversion (R2  = 0.525).

CONCLUSIONS

In total hip arthroplasty, different prosthesis installation directions should be made according to different surgical approaches. Compared with the direct lateral approach, the acetabular anteversion can be intentionally enlarged when using the posterolateral approach. Surgical approach, anterior pelvic plane inclination (APPI), gender, and femoral head diameter were significant predictors of prosthesis orientation. The anterior pelvic plane inclination may be a useful standard for assessing the position of the prosthesis using EOS.

Bi-planar calibration method for templating of hip joint arthroplasty: phantom study and proof of concept

PURPOSE

Calibration of radiographs is a critical step in digital templating for hip arthroplasty. Calibration errors of > 1.5% lead to over- or undersizing of the templated implants and may affect logistics and patient safety. Contemporary calibration methods are known to be imprecise with average errors of 6.5% and wide variance. A novel bi-planar radiograph-based calibration method is proposed, and a phantom study was conducted as proof of concept.

METHODS

A spherical external calibration marker (ECM) is placed in front of the pubic symphysis of a pelvic bone model at twelve different positions. For each marker position, standard anteroposterior radiographs and four corresponding lateral radiographs with different degrees of rotation (0°-30°) are taken (overall, 60 radiographs). Calibration factors are calculated for an internal calibration marker (ICM) at the centre of the right hip (reference) and the ECM using a novel algorithm. Rotation and marker positions simulate foreseeable use errors and misplacements and aim to test robustness of the method against these errors.

RESULTS

ECM calibration factor was 125.9% (range 124.7-127.2), and the mean ICM calibration factor was 126.6% (range 126.2-127.1) ([Formula: see text]). Four images (8.3%) were beyond the 1% error threshold (all with 30° rotation). The mean difference was 0.79% (SD 0.49).

CONCLUSION

The bi-planar method precisely predicts the true calibration factor of the hip joint plane under various conditions. In lateral radiographs, rotation of up to 20° did not adversely affect the precision and all images had calibration errors below the threshold for clinical significance.