Preoperative planning for implant placement with consideration of pelvic tilt in total hip arthroplasty: postoperative efficacy evaluation

Outcomes of Hybrid Total Hip Arthroplasty for Subchondral Insufficiency Fracture of the Femoral Head

Background

The purpose of this study was to evaluate functional outcomes, radiologic results, and complications after hybrid total hip arthroplasty (THA) in patients with subchondral insufficiency fractures (SIFs) of the femoral head.

Methods

From June 2009 to December 2020, among 985 patients who underwent hybrid THA at our hospital, 19 patients diagnosed with SIF through a retrospective chart review were included. Those under 50 years of age, with radiographic findings of osteonecrosis on the contralateral side of surgery, a history of organ transplantation, and alcohol abuse, were excluded. Functional evaluation was performed using a modified Harris Hip Score (HHS). After surgery, inclination and anteversion of the acetabular cup and version of the femoral system were measured using postoperative x-ray. The outpatient follow-up was performed at 6 weeks, 3 months, 9 months, and 12 months after surgery and every year thereafter. Complications including dislocation, implant loosening, stem subsidence, and periprosthetic infection were observed on follow-up radiographs.

Results

The average follow-up time was 29.3 ± 9.1 months (range, 24-64 months) with no loss to follow-up. The mean modified HHS was 83.4 ± 9.6 (range, 65-100) at the last outpatient clinic follow-up. The average inclination of the acetabular cup was 41.9° ± 3.4° (range, 37°-48°), and the anteversion was 27.5° ± 6.7° (range, 18°-39°). The version of the femoral stem was 19° ± 5.7° (range, 12°-29°). There was no case of intraoperative fracture. There were no cases of dislocation, loosening of the cup, subsidence of the femoral stem, intraoperative or periprosthetic fracture, or periprosthetic infection on the follow-up radiographs.

Conclusions

In our study, hybrid THA showed favorable outcomes in patients diagnosed with SIF, and there were no further special considerations as for THA performed due to other diseases or fractures.

Clinical effects of combined anteversion and offset on postoperative dislocation in total hip arthroplasty

BACKGROUND

Implant impingement and soft tissue tension are factors involved in dislocation after total hip arthroplasty (THA). Combined anteversion (CA) has been used as an indicator for implant placement. However, optimal implant placement remains a challenge. Moreover, the effect of changes in offset on dislocation is still unclear. In this study, we aimed to clarify the effects of postoperative CA and pre- and postoperative changes in offset on dislocation.

METHODS

Included were patients who underwent primary cementless THA between 2013 and 2020. The mean values of CA and offset in the dislocation and non-dislocation groups were compared. The CA values within ± 10% of the recommended values were defined as good CA, and those outside the range were rated as poor CA. The dislocation rates were compared between the good and poor CA groups and between the groups with and without increased offset.

RESULTS

A total of 283 hips were included. The mean values of CA in the dislocation and non-dislocation groups were significantly different (P < 0.05). The dislocation rate was significantly lower in the good CA group (P < 0.05). The dislocation rates in the groups with and without increased total offset were 0.5% and 4.3%, respectively (P = 0.004). There were no dislocations in patients with good CA and increased offset.

CONCLUSIONS

The dislocation rate was significantly lower when implants were placed within ± 10% of the recommended CA value. Our results suggest that dislocation can be avoided by placing the implant in the good CA range and considering the increase in total offset on the operative side.

Effectiveness of Flat-Panel Fluoroscopy in Direct Anterior Total Hip Arthroplasty: A Comparison to Image Intensifier Fluoroscopy With Radiopaque Grid

Introduction

The use of traditional, image intensifier fluoroscopy with a radiopaque grid during direct anterior total hip arthroplasty (DA THA) has demonstrated reduced variability in component positioning and operative time compared to fluoroscopy without a grid. A disadvantage of image intensifier fluoroscopy is spatial distortion, particularly compared to flat-panel fluoroscopy systems. The purpose of this study is to determine whether flat-panel fluoroscopy decreases variability in component positioning during DA THA compared to the use of traditional grid fluoroscopy.

Methods

We retrospectively reviewed 70 consecutive DA THAs between February 2020 and February 2021: 36 using flat-panel fluoroscopy, and 34 using traditional fluoroscopy with a grid. Radiographs were independently reviewed by 2 authors to identify components exceeding goal parameters: cup abduction of 40 ± 10 degrees, as well as offset and limb lengths within 10 mm of the contralateral side. Binary values for goal parameter achievement were assigned for each THA.

Results

No significant difference was observed in the number of hips that met goals for cup abduction (100% vs 97%, P = 1.00), hip offset (88% vs 88%, P = 1.00), limb length (91% vs 94% [ ±10 mm], P = .669, 65% vs 72% [±5 mm], P = .498), or for the number of hips that met all 3 component goals (79% vs 80%, P = 1.00). No significant difference in operative time was noted between the 2 groups (110.2 minutes vs 100.9, P = .76).

Conclusions

We demonstrated no significant difference in component positioning in DA THAs utilizing flat-panel fluoroscopy as compared to using traditional fluoroscopy with a grid.

Prediction of Change in Pelvic Tilt After Total Hip Arthroplasty Using Machine Learning

BACKGROUND

A postoperative change in pelvic flexion following total hip arthroplasty (THA) is considered to be one of the causes of dislocation. This study aimed to predict the change of pelvic flexion after THA integrating preoperative and postoperative information with artificial intelligence.

METHODS

This study involved 415 hips which underwent primary THA. Pelvic flexion angle (PFA) is defined as the angle created by the anterior pelvic plane and the horizontal/vertical planes in the supine/standing positions, respectively. Changes in PFA from preoperative supine position to standing position at 5 years after THA were recorded and which were defined as a 5-year change in PFA. Machine learning analysis was performed to predict 5-year change in PFA less than -20° using demographic, blood biochemical, and radiographic data as explanatory variables. Decision trees were constructed based on the important predictors for 5-year change in PFA that can be handled by humans in clinical practice.

RESULTS

Among several machine learning models, random forest showed the highest accuracy (area under the curve = 0.852). Lumbo-lordotic angle, femoral anteversion angle, body mass index, pelvic tilt, and sacral slope were most important random forest predictors. By integrating these preoperative predictors with those obtained 1 year after the surgery, we developed a clinically applicable decision tree model that can predict 5-year change in PFA with area under the curve = 0.914.

CONCLUSION

A machine learning model to predict 5-year change in PFA after THA has been developed by integrating preoperative and postoperative patient information, which may have capabilities for preoperative planning of THA.

Effects of changes in whole-body alignment on ipsilateral knee pain after total hip arthroplasty

BACKGROUND

Total hip arthroplasty decreases hip pain and often reduces knee pain in patients with hip osteoarthritis. Whole-body alignment may be associated with knee pain, but to our knowledge this relationship has not been previously investigated. The purpose of this study was to investigate the effect of changes in whole-body alignment on ipsilateral knee pain in patients after total hip arthroplasty.

METHODS

In total, 94 patients with unilateral hip osteoarthritis who underwent total hip arthroplasty were enrolled in this study. A visual analog scale (VAS) was used to investigate perioperative knee pain. An EOS 2D/3D X-ray system was used to quantify the whole-body alignment of the spine, pelvis, and lower extremities in the standing position. The relationship between perioperative changes in knee pain and whole-body alignment was investigated.

RESULTS

Among 61 patients who had preoperative ipsilateral knee pain, pain resolved in 30 (50%) and persisted in 31 (50%) after surgery. In these patients, average ipsilateral knee pain decreased significantly after surgery, from 41 mm to 14 mm on the VAS (P < 0.01). Preoperative knee pain was correlated with femorotibial rotation, and postoperative knee pain was correlated with K-L grade, preoperative knee pain visualized analog scale, and preoperative sagittal vertical axis. Multiple linear regression identified preoperative sagittal vertical axis as significantly associated with residual postoperative ipsilateral knee pain.

CONCLUSIONS

Ipsilateral knee pain decreased in half of patients after total hip arthroplasty. Patients with a considerable forward-bent posture may have residual ipsilateral knee pain after total hip arthroplasty.

How does corrective fusion surgery for adult spinal deformities affect pelvic inclination in the supine position as the reference plane for THA?

PURPOSE

To determine the changes in pelvic inclination in the supine and standing positions after spinal corrective surgery, and to identify the most predictive factor for changes in pelvic inclination with the supine position as the reference plane for total hip arthroplasty.

METHODS

We retrospectively analysed the data of 124 patients who underwent spinal corrective fusion surgery for adult spinal deformity between 2012 and 2016 at our institution. Spinal parameters were assessed preoperatively and postoperatively using whole spine radiographs in the standing position. The sacral slope (SS) was measured using spine and pelvis computed tomography. Differences between the preoperative and postoperative SS values in each position were calculated as Δsupine SS_{pre post} and Δstanding SS_{pre post}, respectively. We statistically analysed the correlations between Δsupine SS _{pre post} and preoperative spinal parameters to determine the most useful predictor of Δ supine SS_{pre post}.

RESULTS

The mean Δsupine SS_{pre post} of 10.5°(-13°-50°) was significantly smaller than the mean Δstanding SS_{pre post} of 13.2° (-19°-44°) (p = 0.02). Moreover, 21 patients (17%) had Δsupine SS_{pre post} > 20°. The Δsupine SS _{pre post} was correlated with preoperative LL (r = -0.34 p < 0.01), PT (r = 0.42 p < 0.01), and SVA (r = 0.37 p < 0.01). Preoperative supine SS (r = -0.54, p < 0.01) had the highest correlation with Δsupine SS_{pre post}, whereas preoperative standing SS showed no correlation (r = -0.14 p = 0.12).

CONCLUSION

Preoperative supine SS is the most useful predictive factor for changes in supine pelvic inclination, and low preoperative values should be noted. This information should be considered for the management of patients with hip-spine syndrome.

Repeatability of Inertial Measurement Units for Measuring Pelvic Mobility in Patients Undergoing Total Hip Arthroplasty

Consideration of pelvic mobility when positioning implants for total hip arthroplasty (THA) has been shown to reduce the risk of complications such as dislocation, squeaking and excessive wear. We aim to test the repeatability of pelvic tilt measurements taken between three positions (standing, flexed-seated and step-up) by an inertial measurement unit (IMU) and hence, evaluate their reliability in screening for high pelvic mobility in patients undergoing THA. The repeated IMU measurements of pelvic tilt were analysed for consistency and compared with measures taken by x-ray analysis. Our study showed greater variation in measures taken by the IMU particularly in the flexed-seated position. The patient's pelvic tilt in this position negatively correlated with their mid-back angle, suggesting the posture of the patient is a source of variation in the flexed-seated position if not kept consistent during assessments. IMUs were overall able to produce accurate and reliable measurements of pelvic tilt; however, protocols will need to be adjusted to factor in a patient's mid-back angle when taking future readings.

USE OF COMPUTER NAVIGATION IN TOTAL HIP ARTHROPLASTY (LITERATURE REVIEW)

OBJECTIVE

The aim: Analyze the accuracy and ease of use of various computer navigations in total hip arthroplasty.

PATIENTS AND METHODS

Materials and methods: Data from about 50 literature sources for the last two decades have been analysed.

CONCLUSION

Conclusions: Analyzing the accuracy and ease of use of various computer navigations in total hip arthroplasty, we offer two the most promising for further study and improvement systems: a semi-active navigation system and augmented reality system in total hip arthroplasty.

Optimal combined anteversion range for obtaining a wider range of motion without prosthetic impingement after total hip arthroplasty: a three-dimensional analysis study

Background

Obtaining a larger theoretical range of motion (ROM) is crucial to avoid prosthetic impingement after total hip arthroplasty (THA); however, no reports have examined the permissible range values of combined anteversion (CA) satisfying targeted ROM without prosthetic impingement. This retrospective study aimed to evaluate the possible postoperative CA extent that would allow meeting target ROM criteria according to Yoshimine’s theory using computed tomography (CT)-based three-dimensional motion analysis after THA.

Methods

This study included 114 patients (133 hips) who underwent cementless primary THA using a CT-based navigation system and implants (oscillation angle ≥ 135°). Implant positions were determined using Yoshimine's CA formula. Postoperative evaluation was conducted using a three-dimensional templating software for CT data. The postoperative Yoshimine’s and Widmer’s CA was calculated, and the difference between the target and postoperative values was defined as the error of Yoshimine’s CA and Widmer’s CA. Prosthetic ROM was assessed by Yoshimine’s stringent criteria for activities of daily living. Based on fulfilling these criteria, all patients were divided into the ROM (+) and ROM (−) groups. Evaluation items were compared between the two groups.

Results

There were 111 and 22 hips in the ROM (+) and ROM (−) groups, respectively. A significant difference was noted in the absolute error of Yoshimine’s and Widmer’s CA between the two groups. Using receiver operating characteristic analysis, threshold values of 6.0 (higher values indicate greater disability; sensitivity 90.9%, specificity 72.1%) for the absolute Yoshimine’s CA difference (area under the curve [AUC] 0.87, P < 0.01) and 6.9 (higher values indicate greater disability; sensitivity 68.2%, specificity 88.3%) for the absolute Widmer’s CA difference (AUC 0.83, P < 0.01) were predictors in the ROM (−) group.

Conclusions

The target range of Yoshimine’s CA (90.8° ± 6.0°) and Widmer’s CA values (37.3° ± 6.9°) was crucial in implant orientation for obtaining theoretical ROM without prosthetic impingement after THA.

Anterior pelvic plane tilt poorly estimates the sagittal body alignment due to internal rotation of innominate bone

This study investigated the influence of the rotation of innominate bone on anterior pelvic plane (APP) tilt, the angle formed by the APP, and coronal plane of the body to determine whether the provision of proper information about the sagittal balance of the body by the value of the APP tilt (APPT). In total, 244 patients (171 females, 73 males) who were candidates for total hip or knee arthroplasty, periacetabular osteotomy, or shelf arthroplasty were included. The rotational angle of the innominate bone was quantified using computed tomography images at the level of the anterior superior, and anterior inferior iliac spine, and ischiopubic portion. Clustering analysis was performed to identify subtypes of innominate bone rotation. High, intermediate, and low internal rotational alignment groups were identified in females, characterized by rotational angles. Males were treated as one group, and no intergroup differences were observed in sacral slope (SS) and pelvic incidence. However, intergroup differences in APPT were found, indicating a variation in APPT irrespective of sagittal body balance. A negligible relationship between SS and APPT was observed in the high-internal-rotation group, intermediate-internal-rotation group, and male group, whereas a moderate correlation found in the low-internal-rotation group (r = .59). The results could suggest surgeons that the value of the APPT provides no information on the sagittal balance; therefore, it may be ignored for acetabular component positioning during preoperative planning for total hip arthroplasty.

Automatic Characterization of Pelvic and Sacral Measures from 200 Subjects

BACKGROUND

An understanding of pelvic and acetabular morphology and orientation is required for accurate surgical reconstruction of the hip and spine, as well for component placement in a total hip arthroplasty. Our objectives were to develop an automated system for measuring pelvic and sacral orientations utilizing computed tomographic (CT) scans and to characterize these measures across 200 asymptomatic subjects.

METHODS

An automated feature recognition algorithm was created to identify acetabular and pelvic orientation across 200 scans generated for non-musculoskeletal conditions. Three-dimensional models were generated from CT data to serve as inputs to the algorithm. Acetabular orientation was defined by comparing a plane fit to the acetabular rim with the anterior pelvic plane. Pelvic inclination, pelvic tilt, and sacral slope were defined as the angles between landmarks identified across the pelvis: pubic tubercles, acetabular center, left and right anterior superior iliac spines, and sacral plate.

RESULTS

The mean sacral slope was 36.49°, the mean pelvic tilt was 15.60°, and the mean pelvic incidence was 52.05°. The mean sacropubic angle was 32.48° and the mean pelvic-Lewinnek angle was 8.93°. Significant differences between male and female subjects were observed in the sacral slope (mean difference, 4.72°; p < 0.05), pelvic tilt α (mean difference, 4.17°; p < 0.05), pelvic tilt γ (mean difference, 3.06°; p < 0.05), and the pelvic-Lewinnek angle (mean difference, 1.76°; p < 0.05). The comparison of acetabular orientation measures with those in a prior study of the same cohort yielded intraclass correlation coefficients (ICCs) all above 0.97. The validation of sacral orientation via manual measurement also yielded ICC values all at or above 0.97.

CONCLUSIONS

Our algorithm showed a high degree of consistency in acetabular orientation measures with respect to a prior study of the same cohort. The measures of pelvic orientation were found to be accurate and reliable when compared with manual measurements of the same data set. All measurements of pelvic orientation were consistent with the means reported in the literature.

CLINICAL RELEVANCE

An accurate and reproducible, automated technique for determining pelvic and acetabular orientation provides a way to characterize these measures as an aid in clinical diagnosis and preoperative planning.

A Sensor-Based Screening Tool for Identifying High Pelvic Mobility in Patients Due to Undergo Total Hip Arthroplasty

There is increasing evidence that pelvic mobility is a critical factor to consider in implant alignment during total hip arthroplasty (THA). Here, we test the feasibility of using an inertial sensor fitted across the sacrum to measure change in pelvic tilt, and hence screen for patients with high pelvic mobility. Patients (n = 32, mean age: 57.4 years) due to receive THA surgery participated in the study. Measures of pelvic tilt were captured simultaneously using the device and radiograph in three functional positions: Standing, flexed-seated, and step-up. We found a strong correlation between the device and radiograph measures for the change in pelvic tilt measure from standing to flexed-seated position (R² = 0.911); 75% of absolute errors were under 5 degrees. We demonstrated that the device can be used as a screening tool to rapidly identify patients who would benefit from more detailed surgical planning of implant positioning to reduce future risks of impingement and dislocation.

Assessment of pelvic morphology using 3D imaging and analysis in unilateral Crowe-IV developmental dysplasia of the hip

AIMS

Morphological abnormalities are present in patients with developmental dysplasia of the hip (DDH). We studied and compared the pelvic anatomy and morphology between the affected hemipelvis with the unaffected side in patients with unilateral Crowe type IV DDH using 3D imaging and analysis.

METHODS

A total of 20 patients with unilateral Crowe-IV DDH were included in the study. The contralateral side was considered normal in all patients. A coordinate system based on the sacral base (SB) in a reconstructed pelvic model was established. The pelvic orientations (tilt, rotation, and obliquity) of the affected side were assessed by establishing a virtual anterior pelvic plane (APP). The bilateral coordinates of the anterior superior iliac spine (ASIS) and the centres of hip rotation were established, and parameters concerning size and volume were compared for both sides of the pelvis.

RESULTS

The ASIS on the dislocated side was located inferiorly and anteriorly compared to the healthy side (coordinates on the y-axis and z-axis; p = 0.001; p = 0.031). The centre of hip rotation on the dislocated side was located inferiorly and medially compared to the healthy side (coordinates on the x-axis and the y-axis; p < 0.001; p = 0.003). The affected hemipelvis tilted anteriorly in the sagittal plane (mean 8.05° (SD 3.57°)), anteriorly rotated in the transverse plane (mean 3.31° (SD 1.41°)), and tilted obliquely and caudally in the coronal plane (mean 2.04° (SD 0.81°)) relative to the healthy hemipelvis. The affected hemipelvis was significantly smaller in the length, width, height, and volume than the healthy counterpart. (p = 0.014; p = 0.009; p = 0.035; p = 0.002).

CONCLUSION

Asymmetric abnormalities were identified on the affected hemipelvis in patients with the unilateral Crowe-IV DDH using 3D imaging techniques. Improved understanding of the morphological changes may influence the positioning of the acetabular component at THA. Acetabular component malpositioning errors caused by anterior tilt of the affected hemi pelvis and the abnormal position of the affected side centre of rotation should be considered by orthopaedic surgeons when undertaking THA in patients with Crowe-IV DDH. Cite this article: Bone Joint J 2020;102-B(10):1311-1318.

Association of Femoral Rotation With Whole-Body Alignment in Patients Who Underwent Total Hip Arthroplasty

Background

Although rotational changes in lower limb alignment after total hip arthroplasty (THA) affect functional stem anteversion, less is known about the effects of femoral rotational alignment in the standing position. This study investigated postoperative changes in femoral rotation and evaluated the association with whole-body alignment in patients who underwent THA.

Methods

Sixty-five patients with unilateral hip osteoarthritis who underwent THA were enrolled. Preoperative and postoperative femoral rotation in the standing and supine positions were measured using EOS 2D/3D X-ray imaging system and computed tomography. Negative and positive changes in femoral rotation angle were indicative of internal and external rotation, respectively. The associations between femoral rotation and preoperative clinical and radiological factors were investigated.

Results

Femoral rotation showed significant internal changes in both the standing (-4.7° ± 11.0°) and supine (-3.5°± 10.9°) positions after THA. The preoperative femoral rotation angle, knee flexion angle, sagittal vertical axis (SVA), lumbar lordosis, body mass index, age, and internal and external rotation angles of the hip range of motion on the contralateral side were significantly correlated with femoral rotation in the standing position after THA. Multiple regression analysis showed that preoperative femoral rotation (β = 0.416, P < .001) and SVA (β = 0.216, P = .040) were significant predictors of postoperative femoral rotation in the standing position.

Conclusions

Femoral rotation had significant association with the patient-inherent posture represented by the SVA in the standing position. Because extensive external change of femoral rotation may increase the risk of hip impingement and dislocation, careful attention is required in patients with external femoral rotation and forward bent posture in the preoperative standing position.

Utility of CT-based navigation in revision total hip arthroplasty for a patient with severe posterior pelvic tilt-case report

Background

Hip dislocation after total hip arthroplasty (THA) or hemi-arthroplasty is a rare but serious complication. Dislocation may be prevented by appropriate positioning of the cup angle of inclination and anteversion.

Case presentation

This report describes a 66-year-old woman who underwent revision THA using a computer tomography (CT)-based navigation system to treat an anterior dislocation after hemi-arthroplasty due to a severe posterior pelvic tilt. At initial presentation, her sagittal pelvic tilt angle, measured as anterior pelvic plane (APP) in the supine position, was 38 degrees posterior to the coronal plane. Owing to the posterior pelvic tilt, revision THA was performed using CT-based navigation, while dual mobility was utilized to reduce the risk of re-dislocation. Postoperatively, her sagittal pelvic tilt angle showed further progression over time, with an APP of 66 degrees posterior to the coronal plane in the standing position 3 years after revision THA. Simulation with the Zed Hip system showed that the risk of implant-to-implant impingement was much higher posteriorly than anteriorly. Gait analysis demonstrated hyperextension of the hip joint while walking, although hip joint function required for daily activity was maintained.

Conclusions

Preoperative planning of implant orientation, based on posterior progression of pelvic tilt and accurate placement of components, is important to prevent dislocation in patients with severe posterior pelvic tilt. A dual mobility cup may also improve hip function in these patients.

Effect of pelvic tilt and rotation on cup orientation in standing anteroposterior radiographs

BACKGROUND

Individual pelvic tilt and rotation have wide variability that can affect the measurement of cup orientation in anteroposterior (AP) radiographs. The purpose of this study was to analyse the effect of pelvic tilt and rotation on radiographic measurements of cup orientation.

METHODS

A total of 53 patients (63 hips) were included in this study. The patients underwent a computed tomography study with standing AP pelvis radiographs taken both preoperatively and approximately 3 months postoperatively. We used 2-dimensional/3-dimensional matching to measure the pelvic tilt and rotation, and the non-standardised and standardised cup orientation.

RESULTS

There was no difference in the pelvic tilt and rotation between the preoperative and postoperative radiographs. The distribution of the differences between the non-standardised and standardised cup anteversion exhibited a change within 5° in only 34/63 (54%) hips. The pelvic tilt correlated with the difference between the non-standardised and standardised cup anteversion, but the pelvic rotation did not. When all 63 hips were separated into the right and left sides, the pelvic rotation inversely correlated with the pelvic tilt-adjusted difference between the non-standardised and standardised cup anteversion of the right side but directly correlated with that of the left side.

CONCLUSIONS

The current study demonstrated that the measurement of cup anteversion in standing AP radiographs is significantly affected by both the pelvic tilt and pelvic rotation. An improved understanding of the pelvic orientation may eventually allow for desired cup positioning on a patient-specific basis to potentially reduce complications associated with the malposition of the cup.

New combined anteversion technique in hybrid THA: cup-first procedure with CT-based navigation

PURPOSE

Combined anteversion (CA) technique (stem-first procedure) is generally accepted as the optimal technique to attain an appropriate CA value in total hip arthroplasty (THA). However, cup anteversion is strongly influenced by the native femoral anteversion. Accordingly, anterior protrusion of the cup in the acetabulum might occur. The purpose of the present study is to investigate the achievement of the optimal CA while avoiding anterior cup protrusion and examine the significance of our new CA technique with cup-first procedure in hybrid THA.

METHODS

Seventy-nine hybrid THAs with the cup-first procedure used a CT-based navigation system for cup positioning. In the preoperative planning, cup anteversion was aimed at approximately 20°. However, in actuality, sufficient cup coverage in the original acetabulum based on individual anatomy is given priority over cup placement based on CT-based planning to ensure adequate cup coverage. The target stem anteversion was determined following Widmer's mathematical formula (37.3 = femoral stem anteversion × 0.7 + cup anteversion). Cemented stem was inserted according to the target stem anteversion angle.

RESULTS

Regarding the assessment of overall alignment, the calculated Widmer's CA values during surgery and postoperative CT evaluation were 34.1° ± 6.0° (range 20.7°-51.2°) and 35.1° ± 6.7° (range 21.6°-50.7°). There were 72 hips (91.1%) within 25°-50° of CA. Cup protrusion length averaged 2.0 mm ± 2.6 mm (0-8.8 mm) in the axial view and 0.4 mm ± 1.0 mm (0-3.6 mm) in the sagittal view. Cup protrusion length of more than 5 mm was indicated in 10 hips, and no hips observed more than 10 mm.

CONCLUSION

Our new CA technique (cup-first procedure) with hybrid THA was able to achieve optimal CA value while avoiding anterior cup protrusion.

Modern cup alignment techniques in total hip arthroplasty: A systematic review

INTRODUCTION

A systematic review was conducted to assess the clinical and radiological outcomes of the alternative surgical techniques that consider the dynamic aspect of the acetabular orientation when aligning a cup (pelvic tilt-, lumbo-pelvic kinematics-, and spine-hip relationship-adjusted cup alignment techniques).

METHOD

Eight eligible articles reported the outcomes of total hip arthroplasty (THA) performed with alternative techniques. Clinical and radiological data were extracted. One study had a control group of patients who underwent conventional THAs (level III) while the seven other studies were level IV. Computer navigation system (CAS), Optimized Positioning System (OPS™), and manual instrumentation were used to align components in four, two, and two studies, respectively. A meta-analysis was not carried out because there was a lack of homogeneity between included articles regarding the method to position the cup and the nature of the reported data.

RESULTS

THA performed with alternative techniques had an early dislocation rate ranging from 0 to 1.9%, no unexpected catastrophic failure, and acceptable radiographic cup orientations. One study compared kinematically and mechanically aligned THAs and found no dislocation in either groups, similar patient reported outcome measures (43 Oxford-12 Score for both groups), and similar proportions of cup in the Lewinnek zone (respectively 65% and 70%).

DISCUSSION/CONCLUSION

Alternative methods accounting for the functional acetabular orientation seem to be clinically safe and effective in the early-term, and generate acceptable cup orientation on radiographs. Their values compare to those of more conventional techniques for cup implantation remain to be determined. We developed a classification of the multiple methods for aligning an acetabular component.

LEVEL OF EVIDENCE

IV, systematic review of level III and IV studies.

Pre-Surgery Planning of Lower Limbs Major Joints Arthroplasty

BACKGROUND:

Knee and hip joints endoprosthetics are the main surgical method of arthrosis treatment. The epidemiological incidence rate of the disease is growing steadily every year, affecting younger and younger people. Despite the proven tactics of joint endoprosthetics, an important issue is quality planning of surgery.

AIM:

The aim of this research is to develop a device and a method that would contribute to solving the existing challenges of pre-surgery planning of hip endoprosthetics in patients with related pathologies, which have caused compensatory deformation, and making long vertebrarium-pelvis-lower limbs scout images with the patient lying on his back with an axial load in a computer tomography.

METHODS:

Analog X-ray photographs of the pelvis made on film, digital DICOM images, and special planning programs are used for planning. However, according to numerous studies, the disease of the hip joint is not an independently isolated pathology. In most cases, this pathology is accompanied by changes in the lumbar spine. Often, patients prepared for endoprosthetics have a congenital deformity of tarsus or hip segment, which, during the knee, joint endoprosthetics surgery causes difficulties with the installation of an intramedullary guide.

RESULTS:

The results after total knee arthroplasty according to the method modified at the Department showed a reduction of the WOMAC index slightly more than twice down to 37.26 ± 7.92. The number of revision surgeries after endoprosthetics decreased from 5 (5.7%) to 1 (1.1%) for the hip joint, and from 7 (4.3%) to 2 (1.3%) for the knee joint, respectively.

CONCLUSION:

To form a proper guide entry point, it is necessary to assess the segment at the stage of surgery planning and examination of patients, which can be done using the proposed method. To remove the complications during the pre-surgery planning of hip joint endoprosthetics in patients with related pathologies, a device and methods have been developed for obtaining long topograms of the vertebrarium-pelvis-lower limbs complex with the patient lying on his back with the axial load in computer tomography.

The influence of patient factors on femoral rotation after total hip arthroplasty

Background

A postoperative change in femoral rotation following total hip arthroplasty (THA) might be the cause of dislocation due to the change in combined anteversion. However, very few studies have evaluated the femoral rotation angle following THA, or the factors that influence femoral rotation. We aimed to evaluate changes in femoral rotation after THA, and to investigate preoperative patient factors that influence femoral rotation after THA.

Methods

This study involved 211 hips treated with primary THA. We used computed tomography to measure the femoral rotation angle before and one week after THA. In addition, multiple regression analysis was performed to evaluate preoperative patient factors that could influence femoral rotation after THA.

Results

The femoral rotation angle was 0.2 ± 14° externally before surgery and 4.4 ± 12° internally after surgery (p < 0.001). Multiple regression analysis revealed that sex (β = 0.19; p = 0.003), age (β = 0.15; p = 0.017), preoperative anatomical femoral anteversion (β = − 0.25; p = 0.002), and preoperative femoral rotation angle (β = 0.36; p < 0.001) were significantly associated with the postoperative femoral rotation angle. The final model of the regression formula was described by the following equation: [postoperative femoral rotation angle = 5.41 × sex (female: 0, male: 1) + 0.15 × age - 0.22 × preoperative anatomical femoral anteversion + 0.33 × preoperative femoral rotation angle - 10.1].

Conclusion

The current study showed the mean internal change of 4.6° in the femoral rotation angle one week after THA. Sex, age, preoperative anatomical femoral anteversion and preoperative femoral rotation were associated with postoperative femoral rotation. The patients who were male, older, and who exhibited lesser preoperative anatomical femoral anteversion or greater preoperative femoral rotation angles, tended to demonstrate an externally rotated femur after THA. Conversely, patients who were female, younger, and who exhibited greater preoperative anatomical femoral anteversion or lesser preoperative femoral rotation angles, tended to demonstrate an internal rotation of the femur after THA.

The influence of spine-hip relations on total hip replacement: A systematic review

Sagittal pelvic kinematics along with spino-pelvic angular parameters have recently been studied by numerous investigators for their effect on total hip replacement (THR) clinical outcomes, but many issue of spine-hip relations (SHR) are currently unexplored. Therefore, our review aims at clarifying the following questions: is there any evidence of a relationship between articular impingement/dislocation risk in primary THR and (1) certain sagittal pelvic kinematics patterns, (2) pelvic incidence, and (3) types of SHRs? A systematic review of the existing literature utilising PubMed and Google search engines was performed in January 2017. Only clinical or computational studies published in peer-reviewed journals over the last five years in either English or French were reviewed. We identified 769 reports, of which 12 met our eligibility criteria. A review of literature shows that sagittal pelvic kinematics, but not the pelvic incidence, influences the risk of prosthetic impingement/dislocation. We found no study having assessed the relationship between this risk and the types of SHRs. Sagittal pelvic kinematics is highly variable among individuals and certain kinematic patterns substantially influences the risk of prosthetic impingement/dislocation. Recommendations for cup positioning are therefore switching from a systematic to a patient-specific approach, with the standing cup orientation Lewinneck safe zone progressively giving way to a new parameter of interest: the functional orientation of the cup. Based on a recently published classification for SHRs, We propose a new concept of "kinematically aligned THR" for the purposes of THR planning. Further studies are needed to investigate the relevance of such a classification towards the assumptions and hypothesis we have made. Level of evidence,- Level IV, systematic review of level III and IV studies.