An in vivo model for intraoperative assessment of impingement and dislocation in total hip arthroplasty

Do 3-dimensional Spinopelvic Characteristics Normalize After THA? A Prospective, Comparative Study Using Motion Capture Analysis

BACKGROUND

Spinopelvic stiffness (primarily in the sagittal plane) has been identified as a factor associated with inferior patient-reported outcomes (PROs) and increased dislocation risk after THA. Incorporating preoperative spinopelvic characteristics into surgical planning has been suggested to determine a patient-specific cup orientation that minimizes dislocation risk. Sagittal plane radiographic analysis of static postures indicates that patients exhibit a degree of normalization in their spinopelvic characteristics after THA. It is not yet known whether normalization is also evident during dynamic movement patterns, nor whether it occurs in the coronal and axial planes as well.

QUESTIONS/PURPOSES

(1) Does motion capture analysis of sagittal spinopelvic motion provide evidence of normalization after THA? (2) Do changes in coronal and axial plane motion accompany those in the sagittal plane?

METHODS

Between April 2019 and February 2020, 25 patients agreed to undergo motion capture movement analysis before THA for the treatment of hip osteoarthritis (OA). Of those, 20 underwent the same assessment between 8 and 31 months after THA. Five patients were excluded because of revision surgery (n = 1), contralateral hip OA (n = 1), and technical issues with a force plate during post-THA assessment (n = 3), leaving a cohort total of 15 (median age [IQR] 65 years [10]; seven male and eight female patients). A convenience sample of nine asymptomatic volunteers, who were free of hip and spinal pathology, was also assessed (median age 51 years [34]; four male and five female patients). Although the patients in the control group were younger than those in the patient group, this set a high bar for our threshold of spinopelvic normalization, reducing the possibility of false positive results. Three-dimensional motion capture was performed to measure spinal, pelvic, and hip motion while participants completed three tasks: seated bend and reach, seated trunk rotation, and gait on a level surface. ROM during each task was assessed and compared between pre- and post-THA conditions and between patients and controls. Statistical parametric mapping (SPM) was used to assess the timing of differences in motion during gait, and spatiotemporal gait parameters were also measured.

RESULTS

After THA, patients demonstrated improvements in sagittal spinal (median [IQR] 32° [18°] versus 41° [14°]; difference of medians 9°; p = 0.004), pelvis (25° [21°] versus 30° [8°]; difference of medians 5°; p = 0.02), and hip ROM (21° [18°] versus 27° [10°]; difference of medians 6°; p = 0.02) during seated bend and reach as well in sagittal hip ROM during gait (30° [11°] versus 44° [7°]; difference of medians 14°; p < 0.001) compared with their pre-THA results, and they showed a high degree of normalization overall. These sagittal plane changes were accompanied by post-THA increases in coronal hip ROM (12° [9°] versus 18° [8°]; difference of medians 6°; p = 0.01) during seated trunk rotation, by both coronal (6° [4°] versus 9° [3°]; difference of medians 3°; p = 0.01) and axial (10° [8°] versus 16° [7°]; difference of medians 6°; p = 0.003) spinal ROM, as well as coronal (8° [3°] versus 13° [4°]; difference of medians 5°; p < 0.001) and axial hip ROM (21° [11°] versus 34° [24°]; difference of medians 13°; p = 0.01) during gait compared with before THA. The SPM analysis showed these improvements occurred during the late swing and early stance phases of gait.

CONCLUSION

When restricted preoperatively, spinopelvic characteristics during daily tasks show normalization after THA, concurring with previous radiographic findings in the sagittal plane. Thus, spinopelvic characteristics change dynamically, and incorporating them into surgical planning would require predictive models on post-THA improvements to be of use.

LEVEL OF EVIDENCE

Level II, prognostic study.

Sex-based differences in neck selectivity in total hip arthroplasty using a modular femoral neck system

BACKGROUND

Dislocation is a major complication of total hip arthroplasty (THA). The modular femoral neck system provides practical advantages by allowing adjustment of neck version and length in the presence of intraoperative instability. Anatomical studies have identified morphological differences in the hip joint between men and women. Despite sex-based differences in hip morphology, it remains unclear whether such differences affect neck selectivity in THA using a modular neck system and whether this approach achieves anatomical reconstruction, thereby reducing complications such as dislocation. This study aimed to investigate gender differences in neck selectivity in THA with the modular neck system and assess the clinical impact of the modular neck system.

METHODS

A total of 163 THAs using a modular neck system were included in this study. Data on the type of modular neck and intraoperative range of motion (ROM) were retrieved from patient records. Pre- and post-operative leg length differences (LLD) were examined as part of the radiographic assessment. Dislocation was investigated as a postoperative complication.

RESULTS

Neck selectivity did not significantly differ between men and women. The comparison of pre- and post-operative LLD revealed a tendency for varus necks to improve LLD more than version-controlled necks. Furthermore, no significant correlation was found between intraoperative ROM and neck selectivity, or postoperative dislocation and neck selectivity.

CONCLUSIONS

This study on THA with a modular neck system provided valuable insights into sex-based differences in neck selectivity and highlighted the potential benefits of the modular neck system in addressing LLD and preventing postoperative dislocation.

Soft-tissue tension during total hip arthroplasty measured in four patients and predicted using a musculoskeletal model

PURPOSE

Soft-tissue tension around the hip joint is related to the incidence of dislocation after total hip arthroplasty (THA), but it remains difficult to quantify the soft-tissue tension during surgery. In this study, a three-dimensional force sensor-instrumented modular femoral head was developed and used to quantify soft-tissue tension during THA. The forces at the hip joint were also calculated using a three-dimensional musculoskeletal computer model to validate the measured forces.

METHODS

Soft-tissue tension was investigated by measuring the hip joint forces and directions during intraoperative trialing in four patients through passive range of motion (ROM) from 0° extension to 90° flexion. A musculoskeletal model with THA, which was scaled to one of four patients, was developed. The hip joint forces were calculated under the same motion.

RESULTS

Through the passive ROM, the magnitude of soft-tissue tension was greatest when the hip was extended, decreased with flexion to 34°, and progressively increased to flexion at 90°. The mediolateral force component was relatively constant, but the supero-inferior and anterior-posterior force components changed significantly. Within-individual variations were small during three repeated cycles of measurement, but magnitudes varied significantly among patients. Similar force patterns and magnitudes were calculated by the musculoskeletal model.

CONCLUSIONS

This study demonstrates that it is possible to quantify soft-tissue tension and direction during THA with an instrumented head. There was general agreement between the calculated and measured forces in both pattern and magnitude. Including additional subject-specific details would further enhance agreement between the model and measured hip forces.

Elucidation of target implant orientations with the safety range of hip rotation with adduction or abduction during squatting: Simulation based on in vivo replaced hip kinematics

Objectives: The study aimed to elucidate target cup orientation and stem anteversions to avoid impingement between the liner and stem neck even at hip rotation with adduction during the deeply flexed posture.

Methods: A computer simulation analysis was performed on 32 total hip arthroplasty patients applying patient-specific orientation of the components and in vivo hip kinematics obtained from three-dimensional analysis of the squatting motion. The anterior/posterior liner-to-neck distance and impingement were evaluated based on a virtual change in internal/external rotation (0°–60°) and adduction/abduction (0°–20°) at actual maximum flexion/extension during squatting. Cutoff values of cup orientations, stem anteversion, and combined anteversion to avoid liner-to-neck impingements were determined.

Results: The anterior liner-to-neck distance decreased as internal rotation or adduction increased, and the posterior liner-to-neck distance decreased as external rotation or adduction increased. Negative correlations were found between anterior/posterior liner-to-neck distances at maximum flexion/extension and internal/external rotation. Anterior/posterior liner-to-neck impingements were observed in 6/18 hips (18/56%) at 45° internal/external rotation with 20° adduction. The range of target cup anteversion, stem anteversion, and combined anteversion to avoid both anterior and posterior liner-to-neck impingements during squatting were 15°–18°, 19°–34°, and 41°–56°, respectively.

Conclusion: Simulated hip rotations caused prosthetic impingement during squatting. Surgeons could gain valuable insights into target cup orientations and stem anteversion based on postoperative simulations during the deeply flexed posture.

Computer simulation based on in vivo kinematics of a replaced hip during chair-rising for elucidating target cup and stem positioning with a safety range of hip rotation

Background After total hip arthroplasty, dislocation can occur when a patient unexpectedly assumes internal/external limb positions, even during chair-rising, which is a frequently activity of daily life. Therefore, determining the target cup position to avoid impingement in unexpected limb positions using in vivo data of daily life activities is critical. Methods A computer simulation was performed on 21 total hip arthroplasty patients using patient-specific component placements and hip kinematics obtained during chair-rising analysis using image-matching techniques. The liner-to-neck distance and impingement were evaluated by simulating the change in internal/external rotation angle at maximum hip flexion/extension from 0 to 90°. The cutoff values of cup anteversion and combined anteversion at 60° of internal/external rotation were determined. Findings The anterior/posterior liner-to-neck distances were negatively correlated with internal/external rotation angles (r = -0.82 and -0.78, respectively) and decreased by 1.7 and 1.8 mm for every 15° increase, respectively. Three cases (14%) of anterior/posterior impingement were observed at 60° of internal/external rotation angle, respectively. The cutoff values for cup anteversion and combined anteversion to avoid impingement at 60° of internal/external rotation angle were 12°-25°/38°-62°, respectively. The stem anteversion, adjustable by cup anteversion to meet both the target cup anteversion and combined anteversion, was 13°-50°. Interpretation Simulated unintentional internal or external hip rotation, even during chair-rising, caused impingement and posed a dislocation risk. If the stem anteversion is excessively small or large in meeting the target combined anteversion, adjustments to stem anteversion could be recommended in addition to adjustments in cup anteversion.

Innovative Force-PRO device to measure force and implant position in total hip arthroplasty

Total hip arthroplasty (THA) is the appropriate treatment for hip pain, dislocation, and dysfunction. THA refers to surgery to replace a hip implant, which is an effective way to recover normal hip function. The design of an implant imitates hip functions and allows bone growth in the implant area. However, it should be noted that the implant can dislocate after surgery. The main factor that should be considered during surgery is the correct position of the implant component. The acetabular cup of the hip implant should be positioned at [Formula: see text] anteversion and [Formula: see text] inclination. The evaluation of the implant inclination and anteversion during the operation decrease the risk of the implant dislocation after surgery. Developing a new innovative Force-PRO device can aid the doctor in evaluating the force on the surface of the acetabular liner and the angle of the acetabular liner during the hip implant operation. This device consists of two main sensors-force sensors and inertial measurement unit sensors. Furthermore, the 3D printings of an implant's parts should be specifically designed to integrate with these sensors. To develop the graphical user interface application, C[Formula: see text] should be the programming language of use. The graphical user interface application communicates between the device and user via a wireless communication system. CT-based imaging and force gauge measurement are the methods to evaluate the efficiency of this device. For this purpose, the sterile method is considered.

Determining 3D Kinematics of the Hip Using Video Fluoroscopy: Guidelines for Balancing Radiation Dose and Registration Accuracy

BACKGROUND

Video fluoroscopy is a technique currently used to retrieve the in vivo three-dimensional kinematics of human joints during activities of daily living. Minimization of the radiation dose absorbed by the subject during the measurement is a priority and has not been thoroughly addressed so far. This issue is critical for the motion analysis of the hip joint, because of the proximity of the gonads. The aims of this study were to determine the x-ray voltage and the irradiation angle that minimize the effective dose and to achieve the best compromise between delivered dose and accuracy in motion retrieval.

METHODS

Effective dose for a fluoroscopic study of the hip was estimated by means of Monte Carlo simulations and dosimetry measurements. Accuracy in pose retrieval for the different viewing angles was evaluated by registration of simulated radiographs of a hip prosthesis during a prescribed virtual motion.

RESULTS

Absorbed dose can be minimized to about one-sixth of the maximum estimated values by irradiating at the optimal angle of 45° from the posterior side and by operating at 80 kV. At this angle, accuracy in retrieval of internal-external rotation is poorer compared with the other viewing angles.

CONCLUSION

The irradiation angle that minimizes the delivered dose does not necessarily correspond to the optimal angle for the accuracy in pose retrieval, for all rotations. For some applications, single-plane fluoroscopy may be a valid lower dose alternative to the dual-plane methods, despite their better accuracy.

The Outcomes of Total Hip Replacement in Patients with Parkinson's Disease: Comparison of the Elective and Hip Fracture Groups

INTRODUCTION

The aim of the study was to compare the clinical outcomes following elective and traumatic total hip arthroplasty in Parkinson's disease patients.

MATERIALS AND METHODS

Ten patients with osteoarthritis comprise the elective group (mean age at operation 74 years; mean follow-up 82 months). Thirteen patients with femoral fracture comprise the hip fracture group (mean age 76 years; mean follow-up 54 months). All patients were followed up at 6 and 36 months postoperatively and at the time of the latest follow-up.

RESULTS

Despite the significant improvement in Merle d'Aubigné-Postel and pain scores, disability related to Parkinson's disease increased during the follow-up. Whereas more than 1/3 of hip fracture patients and all elective patients walked independently at 36 months after total hip arthroplasty, 43% of living patients from both groups were able to walk independently at the time of the latest follow-up. The medical complications were seen mainly in patients with hip fracture.

CONCLUSIONS

Excellent pain relief with preserved walking ability without support of another person and acceptable complication profile was observed in Parkinson's disease patients at 36 months after elective total hip arthroplasty. This procedure may be indicated in Parkinson's disease patients after careful and individualized planning.

Dynamic hip kinematics in patients with hip osteoarthritis during weight-bearing activities

BACKGROUND

There is an interest in quantifying the hip kinematics of patients with end-stage hip disorders before total hip arthroplasty. The purpose of the present study was to obtain dynamic hip kinematics under four different conditions, including deep flexion and rotation, in patients with osteoarthritis of the hip.

METHODS

Continuous X-ray images were obtained in 14 patients during gait, chair-rising, squatting, and twisting, using a flat panel X-ray detector. These patients received computed tomography scan to generate virtual digitally reconstructed radiographs. The density-based digitally reconstructed radiographs were then compared with the serial X-ray images acquired using image correlations. These 3D-to-2D model-to-image registration techniques determined the 3D positions and orientations of the pelvis and femur during the movement cycle of each activity.

FINDINGS

For gait, chair-rising, and squatting, the maximum hip flexion angles averaged 22°, 64°, and 68°, respectively. The pelvis was tilted anteriorly by an average of around 7° during the full gait cycle. For chair-rising and squatting, the maximum absolute values of anterior/posterior pelvic tilt averaged 8°/17° and 6°/18°, respectively. Hip flexion showed maximum flexion angle on the way of movement due to further anterior pelvic tilt during both chair-rising and squatting. For twisting, the maximum absolute values of internal/external hip rotation averaged 3°/13°.

INTERPRETATION

Patients with hip osteoarthritis prior to total hip arthroplasty demonstrated the limited ranges of coordinated motion of the pelvis, femur, and hip joint during each activity, especially in deeply flexed and rotated postures.

Mobile Biplane X-Ray Imaging System for Measuring 3D Dynamic Joint Motion During Overground Gait

Most X-ray fluoroscopy systems are stationary and impose restrictions on the measurement of dynamic joint motion; for example, knee-joint kinematics during gait is usually measured with the subject ambulating on a treadmill. We developed a computer-controlled, mobile, biplane, X-ray fluoroscopy system to track human body movement for high-speed imaging of 3D joint motion during overground gait. A robotic gantry mechanism translates the two X-ray units alongside the subject, tracking and imaging the joint of interest as the subject moves. The main aim of the present study was to determine the accuracy with which the mobile imaging system measures 3D knee-joint kinematics during walking. In vitro experiments were performed to measure the relative positions of the tibia and femur in an intact human cadaver knee and of the tibial and femoral components of a total knee arthroplasty (TKA) implant during simulated overground gait. Accuracy was determined by calculating mean, standard deviation and root-mean-squared errors from differences between kinematic measurements obtained using volumetric models of the bones and TKA components and reference measurements obtained from metal beads embedded in the bones. Measurement accuracy was enhanced by the ability to track and image the joint concurrently. Maximum root-mean-squared errors were 0.33 mm and 0.65° for translations and rotations of the TKA knee and 0.78 mm and 0.77° for translations and rotations of the intact knee, which are comparable to results reported for treadmill walking using stationary biplane systems. System capability for in vivo joint motion measurement was also demonstrated for overground gait.

Impingement and stability of total hip arthroplasty versus femoral head resurfacing using a cadaveric robotics model

We identified and compared the impingent-free range of motion (ROM) and subluxation potential for native hip, femoral head resurfacing (FHR), and total hip arthroplasty (THA). These constructs were also compared both with and without soft tissue to elucidate the role of the soft tissue. Five fresh-frozen bilateral hip specimens were mounted to a six-degree of freedom robotic manipulator. Under load-control parameters, in vivo mechanics were recreated to evaluate impingement free ROM, and the subluxation potential in two "at risk" positions for native hip, FHR, and THA. Impingement-free ROM of the skeletonized THA was greater than FHR for the anterior subluxation position. For skeletonized posterior subluxations, stability for THA and FHR constructs were similar, while a different pattern was observed for specimens with soft tissues intact. FHR constructs were more stable than THA constructs for both anterior and posterior subluxations. When the femoral neck is intact the joint has an earlier impingement profile placing the hip at risk for subluxation. However, FHR design was shown to be more stable than THA only when soft tissues were intact.

Notching of the femoral stem neck in metal-on-metal total hip replacement: a case report

We report a case of impingement in a metal-on-metal total hip replacement causing both notching of the femoral stem neck and aseptic loosening of the acetabular component. The acetabular component was inserted in excessive anteversion. The femoral stem and acetabular components were retrieved. A larger femoral head was used, and an acetabular component was placed in a less anteverted position. Intra-operative testing through different ranges of movement is recommended to identify potential impingement.

A novel dual fluoroscopic imaging method for determination of THA kinematics: in-vitro and in-vivo study

Accurate measurement of six-degrees-of-freedom in-vivo kinematics of the total hip arthroplasty (THA) is essential in gaining insights into in-vivo THA performance. The objective of this study was to validate a novel dual fluoroscopy imaging system (DFIS) for determination of the THA kinematics using both in-vitro and in-vivo approaches. The in-vitro validation utilized cadaveric hip specimens to compare the THA motion using the DFIS technique with those measured by a radiostereometric analysis (RSA). The differences between the DFIS technique and the RSA were within 0.33±0.81 mm (mean±SD) in translation and 0.45±0.65° in rotation during dynamic motion of the hips. In the in-vivo validation, the THA kinematics of two patients during a treadmill gait was assessed for the feasibility/repeatability of the DFIS technique in measurement of THA kinematics. The poses of the THAs during the treadmill gait was measured using the DFIS technique with the maximum standard deviation of 0.35 mm in translation and of 0.55° in rotation. This study demonstrated that the DFIS technique has comparable accuracy of the RSA and is highly repeatable for measurement of dynamic THA motion, suggesting that the DFIS is a promising tool in evaluating the in-vivo THA biomechanics during functional activities.

Dual-mobility bearings: a review of the literature

Dislocation after total hip arthroplasty remains a major problem and hip instability is the most common reason for revision. These complications are costly to both patients and the healthcare system, and efforts to reduce them have had varied degrees of success. Although there are well documented patient and surgical risk factors for dislocation, the typical surgical solutions offered (constrained liners, large femoral heads) have the drawbacks of reduced range-of-motion and high rates of revision. Dual-mobility prostheses (unconstrained tripolar prostheses) are hip design solutions to dislocation that aim to provide a greater stability with an increased range-of-motion, along with potentially reduced wear. The mean overall dislocation rate from multiple combined studies using dual-mobility prostheses was 0.1% for primary total hip arthroplasty and 3.5% for revisions, compared with 2-7% for standard primary total hip arthroplasties and up to 16% for revisions. Dual-mobility prostheses offer a viable option for treating recurrent dislocation as well as for primary and revision arthroplasty.

In vivo kinematic analysis of squatting after total hip arthroplasty

BACKGROUND

The in vivo kinematics of squatting after total hip arthroplasty is unclear. The purpose of the present study was to determine the range of motion of the hip joint during squatting after total hip arthroplasty.

METHODS

Using fluoroscopy, we investigated 15 primary cementless total hip arthroplasties performed using a computed tomography-based navigation system. An acetabular component with concavities around the rim and a femoral component with reduced neck geometry were used. The motion of the acetabular and femoral components based on the neutral standing position was analyzed using a two-dimensional to three-dimensional registration technique.

FINDINGS

No prosthetic impingement occurred in any hips. The mean maximum hip flexion range of motion was 86.2° (range, 55.1°-117.4°) and was not always consistent with maximum squatting. The mean maximum pelvic posterior tilting angle was 25.7° (range, 5.5°-43.5°). The pelvis began to tilt posteriorly at 50°-70° of the hip flexion range of motion. At maximum squatting, the mean ratio of the pelvic posterior tilting angle to the femoral flexion angle was 23.2% (range, 3.8%-45.7%). The mean minimum angle up to the theoretical prosthetic impingement was 26.2° (range, 11.8°-39.8°).

INTERPRETATION

Although this is a preliminary study, three-dimensional assessment of dynamic squatting motion after total hip arthroplasty using the two-dimensional to three-dimensional registration technique appears to enable elucidation of the range of motion of the hip joint, the contribution of pelvic posterior tilting, and the minimum angle up to theoretical prosthetic impingement during squatting.

Kinematic assessment of hip movement when retrieving an object from the floor

Background

Activities that require extreme hip movement can dislocate hip implants in the early post operative phase. One such activity is retrieving an object from the floor. The aim of this study was to assess hip movement using four different techniques to accomplish this task. This assessment would identify the techniques least likely to cause a hip dislocation.

Methods

An electromagnetic tracker was used to measure the movement of 50 hips in 25 normal subjects. Sensors were attached over the iliac crest and the mid-shaft of the lateral thigh. Data was then collected for 3 repetitions of each of the following retrieval techniques:-

1. Flexing forward to pick up an object between the feet.

2. Flexing to pick up an object lateral to the foot.

3. Squatting to pick up an object between the feet.

4. Kneeling on one knee to pick up beside the knee.

Results

Kneeling required a mean movement of 30.4 degree(s) flexion and 7.2 degree(s) external rotation. This was significantly less than all the other techniques (paired t-test, P << 0.001). Squatting required 87.4 degree(s) flexion and 10.1 degree(s) internal rotation.

Conclusion

The study showed that squatting had the most flexion and internal rotation, whereas kneeling has the least flexion. Thus, to minimise the dislocation risk when retrieving an object from the floor, kneeling should be adopted and squatting should be avoided.