Mid-term results of cementless total hip replacement using a ceramic-on-ceramic bearing with and without computer navigation

A Novel Device for Intraoperative Measurement of Stem Anteversion Angle in Total Hip Arthroplasty

Background

Stem anteversion plays a crucial role in mitigating postoperative complications in total hip arthroplasty (THA). The application of the combined-anteversion theory in THA necessitates the intraoperative measurement of the stem anteversion angle (SAA). However, estimating SAA intraoperatively poses challenges for surgeons lacking a computer-assisted navigation system. In this study, we assessed the precision of intraoperative SAA measurements using a recently developed device, comparing them with 3-dimensional measurements obtained from postoperative computed tomography.

Methods

We examined 127 hips in 127 patients who underwent unilateral THA at our institution. Employing our newly constructed device, attachable to rasping broach handles, we measured the SAA intraoperatively. This process involved incorporating the correction angle derived from the preoperative epicondylar view. We then compared the postoperative SAA with the intraoperative measurements, both with and without the correction angle, to ascertain the device's utility.

Results

The device yielded an intraoperative SAA measurement of 17.93 ± 7.53°. In contrast, the true SAA measured on postoperative computed tomography was 26.40 ± 9.73°. The discrepancy between intraoperative and true SAA was 8.94 ± 5.44° (without the correction angle) and 4.93 ± 3.85° (with the correction angle). Accuracy within a discrepancy of <5° was achieved in 77 cases (60.6%), and <10° was achieved in 113 cases (89.0%). The accuracy remained consistent regardless of the stem-placement angle (varus/valgus, or flexion/extension) or the presence of ipsilateral knee osteoarthritis.

Conclusions

The SAA-measuring device, attachable to various rasping handles, proves useful for straightforward, cost-effective, and noninvasive intraoperative SAA measurement during THA.

Digital protractor as an intraoperative guide to cup anteversion in total hip arthroplasty

INTRODUCTION

To explore if digital protractor could guide the anteversion of acetabular cup during primary THA and make it consistent with preoperative.

METHODS

We retrospectively reviewed 172 cases of primary THA with direct anterior approach (DAA) over 2 years. The anteversion of acetabular cup were measured from computed tomography (CT) scan preoperative and de-identified plain radiographs postoperative by two blinded investigators who were not involved in the surgery. The effect of the digital protractor on the anteversion was determined using regression analysis.

RESULTS

The mean anteversion for the THAs in digital protractor group was 15.5°and 21.4°in control group (P < 0.01). The mean anteversion bias for the THAs in digital protractor group was 1.59° and 6.63° in control group (P < 0.01).Regression analysis identified a 10.7% difference in anteversion due to the use of digital protractor (P < 0.01), and THAs performed without digital protractor were six times more likely to result in anteversion of > 25°. The correlation coefficient for the interobserver reliability of the measurement of the two investigators was 0.94.

CONCLUSION

The digital protractor is a practical tool in the DAA for THA to determine the anteversion of the acetabular prosthesis.

Rigid fixation of pelvic tracker essential for accurate cup placement in CT-based navigation total hip arthroplasty

Research is lacking on the effect of intraoperative pelvic tracker displacement relative to the pelvis on cup orientation accuracy in computed tomography (CT)-based navigation (CTN) or multivariable analysis to detect factors associated with CTN accuracy. Here, we asked: (1) how pelvic tracker displacement influences the CTN accuracy of cup orientation in total hip arthroplasty (THA)? and (2) what factors are associated with CTN accuracy on multivariable analysis? Regarding cup orientation in 446 THA procedures using CTN, we evaluated clinical error defined as the difference between postoperative measurement and preoperative planning and measurement error defined as the difference between postoperative and intraoperative measurements. Multivariable regression analyses detected the associated factors. Subjects with an intraoperative tracker displacement of < 2 mm were classified in the verified group. Mean absolute clinical and measurement errors were < 1.5° in the verified group, whereas the measurement error of 2.6° for cup inclination and 1.3° for anteversion was larger in the non-verified versus verified group. Tracker displacement and screw fixation were associated with larger clinical errors, while tracker displacement and surgeon inexperience were associated with larger measurement errors. Clinical and measurement accuracies were high for CTN cup placement with rigid pelvic tracker fixation.

Effect of hip flexion contracture on the pelvic sagittal tilt in the supine position: A retrospective case-series study

OBJECTIVES

The functional pelvic plane, which adopts the natural pelvic sagittal tilt in the supine position, is a good reference for determining the cup angle in total hip arthroplasty. However, hip flexion contracture may change pelvic tilt postoperatively by the release of contracture. This study investigated the influence of hip flexion contracture on pelvic sagittal tilt in the supine position.

METHODS

This study included 300 patients who underwent primary unilateral total hip arthroplasty. We divided the participants into two groups: with a preoperative hip extension angle of <0° (hip flexion contracture group) and without (non-contracture group). The pelvic sagittal tilt and femoral flexion angle were investigated using computed tomography or pelvic radiographs performed preoperatively and postoperatively.

RESULTS

The femoral flexion angle had significantly reduced postoperatively in the hip flexion contracture group but remained unchanged in the non-contracture group. The preoperative and postoperative pelvic sagittal tilt showed no significant differences between the two groups up to 1 year postoperatively.

CONCLUSIONS

The influence of hip flexion contracture on the pelvic sagittal tilt in the supine position was minimal. The functional pelvic plane in the supine position could be a good reference to ascertain the cup orientation, even in hip flexion contracture cases.

Challenges of Integrating New Technologies for Orthopedic Doctors to Face up to Difficulties during the Pandemic Era

In the field of orthopedics, competitive progress is growing faster because new technologies used to facilitate the work of physicians are continuously developing. Based on the issues generated in the pandemic era in this field, a research study was developed to identify the intention of orthopedic doctors to integrate new medical technologies. The survey was based on a questionnaire that was used for data collection. The quantitative study registered a sample of 145 orthopedic doctors. The data analysis was performed based on the IBM SPSS program. A multiple linear regression model was applied, which analyzed how the independent variables can influence the dependent variables. After analyzing the data, it was observed that the intention of orthopedic doctors to use new medical technologies is influenced by the advantages and disadvantages perceived by them, the perceived risks, the quality of the medical technologies, the experience of physicians in their use, and their receptivity to other digital tools. The obtained results are highly important both for hospital managers and authorities, illustrating the main factors that influence doctors to use emergent technologies in their clinical work.

Anterior superior iliac spine is not always reliable as a pelvic reference axis. -3D study of pelvic axis

BACKGROUND

This study aims to evaluate the accuracy of the axis connecting both anterior superior iliac spines (ASIS axis) as the absolute pelvic axis. No study has ever verified the accuracy of ASIS axis particularly on the AP pelvic radiograph, which cannot be specified on it.

METHODS

Sixty patients who underwent total knee arthroplasty and fifty patients with femoral neck fracture were recruited as subjects without hip deformities and their CT scan data were collected. We defined the line through both center of femoral heads as absolute reference axis of pelvis three-dimensionally. On the coronal plane, the errors between the femoral head axis and the axes through six pelvic landmarks in total, including ASIS were analyzed. On the axial plane, the errors of the lines through four landmarks were analyzed in the same way. Finally, on the coronal images, the mediolateral diameter of the obturator foramen and the mediolateral distance between the midline of the sacrum and the pelvic cavity were measured to evaluate bilateral symmetry of the pelvis.

RESULTS

The errors tended to be smaller as the axes were closer to the femoral head axis (axes connecting bilateral superior aspects of the acetabulum and the teardrops) and the ASIS axis errors were moderate. The obturator foramen based on the ASIS axis was more asymmetrical than the femoral head axis.

CONCLUSION

Adjusting the pelvic tilt and rotation, surgeons should not always rely on the ASIS and refer to appropriate, close to the hip joint references in each case.

Does functional planning, 3D templating and patient-specific instrumentation improve accuracy in total hip replacement?- a randomized controlled trial

AIMS

Debate continues as to the optimal orientation of the acetabular component in total hip arthroplasty (THA) and how to reliably achieve this. The primary objective of this study was to compare functional CT-based planning and patient-specific instruments with conventional THA using 2D templating.

METHODS

A pragmatic single-center, patient-assessor blinded, randomized control trial of patients undergoing THA was performed. 54 patients (aged 18-70) were recruited to either Corin Optimized Positioning System (OPS) or conventional THA. All patients received a cementless acetabular component. All patients underwent pre- and postoperative CT scans, and four functional X-rays. Patients in the OPS group had a 3D surgical plan and bespoke guides made. Patients in the conventional group had a surgical plan based on 2D templating X-rays. The primary outcome measure was the mean error in acetabular anteversion as determined by postoperative CT scan.

RESULTS

There was no statistically significant difference in the mean error in angle of acetabular anteversion when comparing OPS and conventional THA. In the OPS group, the achieved acetabular anteversion was within 10° of the planned anteversion in 96% of cases, compared with only 76% in the conventional group. The clinical outcomes were comparable between the groups.

CONCLUSION

Large errors in acetabular orientation appear to be reduced when CT-based planning and patient-specific instruments are used compared to the standard technique but no significant differences were seen in the mean error.

Accuracy of Acetabular Cup Placement During Total Hip Arthroplasty in Supine Position Using a Pelvic Rotation Correction Device

Background

Accurate cup placement during total hip arthroplasty (THA) is difficult because the intraoperative pelvic position changes even in supine patient position. We developed a device known as HipPointer; it corrects pelvic rotation and creates a functional pelvic plane as a reference. The aim of this study was to determine the device placement accuracy and investigate causes of error.

Material and methods

HipPointer was used for cup placement in 353 hips of 308 patients who underwent direct-anterior-approach THA in supine position. The mean age at surgery and body mass index were 63.9 (17-90) years and 24.9 (16.6-42.0) kg/m², respectively. The mean observation period was 40.5 (12-73) months. To investigate the accuracy of HipPointer, preoperative planning and postoperative cup placement angles relative to the functional pelvic plane were evaluated using a three-dimensional analysis software, and absolute errors were determined.

Results

The means ± standard deviations of radiographic inclination (RI) and radiographic anteversion (RA) were 40.2 ± 3.0° and 15.8 ± 3.6°, respectively. The absolute errors of RI and RA were 2.2 ± 2.0° and 2.7 ± 2.3°, respectively. The ratio of the cup placement angle for which both RI and RA are ≤10° in the target zone was 99% (350/353 hips), and the ratio of the absolute errors for which both RI and RA are ≤5° was 80.4% (284/353 hips).

Conclusions

HipPointer is simple in structure, easy to use, and useful for direct-anterior-approach THA in supine position. It provides good cup placement accuracy.

High Risk of Neck-liner Impingement and Notching Observed with Thick Femoral Neck Implants in Ceramic-on-ceramic THA

BACKGROUND

Recently, impingement between the femoral stem and ceramic liner, which appears as a notch in the stem neck on radiographs, has emerged as a new complication. However, the proportion of impingement, potential risk factors, and related complications are poorly elucidated.

QUESTION/PURPOSES

In patients who underwent ceramic-on-ceramic (CoC) THA and had at least 10 years of follow-up, we asked: (1) What proportion had radiographic evidence of stem neck-ceramic liner impingement (notching of the stem), and what implant design, implantation factors, or complications such as ceramic fracture or metallosis are associated with impingement? (2) How common are the complications of noise and ceramic fracture? (3) What are the radiologic changes (including fixation of femoral and acetabular components, osteolysis, and heterotopic ossification) and clinical outcomes as determined by the modified Harris hip score (mHHS) for this cohort? (4) What is the survivorship with implant revision as the endpoint and with reoperation for any reason as the endpoint after CoC THA using a thick-neck stem design?

METHODS

Between May 2003 and April 2010, 643 patients underwent primary THA at a tertiary referral hospital. After excluding patients with metal-on-polyethylene and with ceramic-on-polyethylene implants, 621 patients were considered eligible for this study. All patients received the same hemispherical titanium cup, a standard-length tapered titanium stem, and a CoC bearing. Of those, 19% (115) were lost to follow-up before 10 years, and 8% (50) were excluded because they died before the minimum follow-up duration of 10 years, leaving 73% (456) for analysis. Patients had a mean age of 50 ± 14 years and were followed for a median (range) of 13 years (10 to 17). The mean cup abduction was 38° ± 5°, and the mean cup anteversion was 26° ± 7°. To determine the proportion of patients with the neck-liner impingement, we analyzed the plain radiographs of every patient during follow-up to detect notches around the stem. The detection of stem neck notches on the radiographs was reliable (intraobserver reliability: κ = 0.963; p < 0.001 and interobserver reliability: κ = 0.975; p < 0.001). To evaluate factors related to notching, we compared the possible confounding factors including gender, age, BMI, implant position, neck length, and head diameter. Complications such as ceramic fracture, noise, dislocation, and periprosthetic joint infection were recorded. Noise was evaluated via interview and with the Hip Noise Assessment Questionnaire, which assessed the noise qualitatively. For clinical outcome, we assessed the mHHS, which includes pain and function scales (0 [worst] to 100 [best]), every visit. Tilting of at least 4° or migration of at least 4 mm was the criteria for cup loosening; subsidence more than 3 mm, any change in position, or a continuous radiolucent line greater than 2 mm was the criteria for stem loosening. To evaluate osteolysis, we performed CT scans in 57% (262 of 456) of patients. Kaplan-Meier survivorship analysis was performed using the endpoints of survivorship free from implant revision and survivorship free from reoperation for any cause.

RESULTS

The proportion of stem neck notching was 11% (49 of 456). There were no differences in cup abduction and anteversion between hips with notches and those without notches. Notched hips were more likely to have 28-mm than 32-mm heads (90% [44 of 49] versus 70% [285 of 407]; odds ratio 3.77 [95% CI 1.46 to 9.73]; p = 0.004). None of the 49 notched hips had a ceramic head or liner fracture or evidence of metallosis. A ceramic head fracture was reported in 2% (9 of 456); all fractures occurred in 28-mm short neck heads. A ceramic liner fracture occurred in 0.2% (1 of 456), and noise was noted in 6% (27 of 456). Acetabular osteolysis developed in 2% (7 of 456). The mHHS was 91 ± 12 points at the final follow-up. The survivorship free from implant revision was 97% (95% CI 96% to 99%), and the survivorship free from reoperation for any cause was 96% (95% CI 95% to 98%) at 13 years.

CONCLUSION

The proportion of stems with neck-ceramic liner impingement and ceramic component fracture were unacceptably high after the use of a thick-neck stem design, especially when a 28-mm head was used. We have discontinued the use of this stem design and we recommend that such stems should not be used when CoC bearings are used. As these findings might be generalized to other bearing couples, further studies focused on polyethylene liner wear and local metallosis due to thick stem neck are warranted.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Effectiveness of a patient-specific guide for femoral stem implantation in primary total hip arthroplasty: a randomized control trial

PURPOSE

The purpose of the present study was to evaluate the efficacy and feasibility of a novel CT-based patient-specific femoral alignment guide (PSG) as compared with conventional pre-operative planning during THA.

METHODS

From March 2020 to September 2020, patients receiving unilateral primary THA were enrolled and randomly allocated to the conventional pre-operative planning group and the PSG group. Primary outcomes were radiographic measurements including lower limb length, femoral offset, femoral anteversion and stem varus/valgus angle, and post-operative perception of leg length discrepancy (LLD). Secondary outcomes were surgical time, intra-operative blood loss, total blood loss, visual analogue scale (VAS), and Harris Hip Score (HHS). The occurrence of post-operative complications was also recorded.

RESULTS

Of the 104 patients screened, 80 cases were enrolled for analysis. The demographics of the two groups were similar. The PSG group illustrated significant improvements (p < 0.001) in lower limb length, femoral offset, femoral anteversion, and stem varus/valgus angle. Patients in the PSG group showed more favourable HHS (p < 0.001) at seven day, four week, andthree month (p = 0.003) follow-up. Perception of LLD was found significantly lower in the PSG group at three tmonth (p = 0.043), six month (p = 0.025), and 12-month (p = 0.048) follow-up. Utilization of the PSG had no significant increase in operative time, intra-operative blood loss, total blood loss, or VAS. No complication was noted in either group.

CONCLUSION

Relative to conventional pre-operative planning, the application with the PSG could potentially provide a simple and reliable solution for improving femoral prosthesis orientation in THA with high accessibility and low healthcare costs. TRN: ChiCTR2000031043 Date of registration: 2020/3/21.

Effectiveness of an accelerometer-based portable navigation for intraoperative adjustment of leg length discrepancy in total hip arthroplasty in the supine position

BACKGROUND

This study aimed to examine the accuracy of the HipAlign® accelerometer-based portable navigation system by measuring the intraoperative leg length change of patients who underwent total hip arthroplasty (THA) and comparing the measured leg length discrepancy (LLD) determined by the navigation system and a freehand technique.

METHODS

A total of 61 patients who underwent THA using the anterolateral approach in the supine position were included in this study and divided into two groups: those who underwent THA with navigation (Group N; N = 31) and with the freehand technique (Group F; N = 30). Statistical analyses were performed to compare the intraoperative leg length change, pre- and post-LLD, absolute values of post-LLD, and the number of patients with the postoperative LLD within 10 mm and 5 mm between the two groups. Additionally, we examined the correlation between the leg length change obtained through intraoperative navigation and measured from the radiographs. Moreover, to evaluate the navigation accuracy, we examined the correlation between the absolute error of leg length change and cup orientation.

RESULTS

The postoperative LLD was significantly lower and the number of patients with the postoperative LLD within 5 mm was significantly higher in Group N, compared with Group F. Additionally, the amount of leg length change measured intraoperatively by the navigation system was strongly correlated with the values obtained by the postoperative radiographic measurement with a small absolute error and minimal wasted time. Moreover, a significant positive correlation was found between the absolute error of the leg length change and that of the cup inclination.

CONCLUSIONS

Our study demonstrates that the accelerometer-based portable navigation system is useful for the intraoperative adjustment of leg length discrepancy during THA for patients in the supine position, as it provides good accuracy and minimizes required time for use.

Notching of the Neck After Acetabular Constraint Necessitating Femoral Component Revision

A 75-year-old woman who had previously undergone a left revision total hip arthroplasty with the use of a constrained acetabular liner presented with recurrent dislocation of the hip. Intraoperatively, there was metallic staining of the hip capsule and significant notching of the femoral neck, consistent with impingement of the intact locking ring, necessitating stem revision. Constrained acetabular liners have high failure rates due to intraprosthetic impingement, but to our knowledge, failure due to notching of the femoral component and metallosis from repeated impingement has not been described. Surgeons should be aware of this potential mode of failure.

Can robotic technology mitigate the learning curve of total hip arthroplasty?

Aims

Traditionally, acetabular component insertion during total hip arthroplasty (THA) is visually assisted in the posterior approach and fluoroscopically assisted in the anterior approach. The present study examined the accuracy of a new surgeon during anterior (NSA) and posterior (NSP) THA using robotic arm-assisted technology compared to two experienced surgeons using traditional methods.

Methods

Prospectively collected data was reviewed for 120 patients at two institutions. Data were collected on the first 30 anterior approach and the first 30 posterior approach surgeries performed by a newly graduated arthroplasty surgeon (all using robotic arm-assisted technology) and was compared to standard THA by an experienced anterior (SSA) and posterior surgeon (SSP). Acetabular component inclination, version, and leg length were calculated postoperatively and differences calculated based on postoperative film measurement.

Results

Demographic data were similar between groups with the exception of BMI being lower in the NSA group (27.98 vs 25.2; p = 0.005). Operating time and total time in operating room (TTOR) was lower in the SSA (p < 0.001) and TTOR was higher in the NSP group (p = 0.014). Planned versus postoperative leg length discrepancy were similar among both anterior and posterior surgeries (p > 0.104). Planned versus postoperative abduction and anteversion were similar among the NSA and SSA (p > 0.425), whereas planned versus postoperative abduction and anteversion were lower in the NSP (p < 0.001). Outliers > 10 mm from planned leg length were present in one case of the SSP and NSP, with none in the anterior groups. There were no outliers > 10° in anterior or posterior for abduction in all surgeons. The SSP had six outliers > 10° in anteversion while the NSP had none (p = 0.004); the SSA had no outliers for anteversion while the NSA had one (p = 0.500).

Conclusion

Robotic arm-assisted technology allowed a newly trained surgeon to produce similarly accurate results and outcomes as experienced surgeons in anterior and posterior hip arthroplasty.

Cite this article: Bone Jt Open 2021;2(6):365–370.

Difference in tapered wedge stem alignment between supine and lateral position in cementless total hip arthroplasty via modified Watson-Jones anterolateral approach

BACKGROUND

Whether different body positions during surgery affect postoperative stem alignment in total hip arthroplasty (THA) remains unclear. The purpose of this study was to clarify differences in tapered wedge stem alignment between supine and lateral positions in THA under the modified Watson-Jones anterolateral approach.

METHODS

We reviewed 242 consecutive, primary cementless THAs performed with ceramic-on-cross-linked polyethylene via the modified Watson-Jones approach in either supine or lateral positions between 2009 and 2015 (supine group: 113 cases; lateral group: 129 cases). No specific reasons to select supine or lateral positions for the surgery were given during the study period. Computed tomography was performed pre- and postoperatively to measure preoperative femoral anteversion and postoperative stem anteversion, respectively. Stem alignment in coronal and sagittal planes was also evaluated.

RESULTS

Mean difference in stem anteversion and femoral anteversion was 8.6 ± 9.4 in the supine position and 13.0 ± 11.4 in the lateral position (p = 0.0013). Although no significant difference was seen between groups for stem alignment in the coronal plane, flexed implantation was more likely in the supine group (46/113, 40.7%) than in the lateral group (20/129, 15.5%). A significant correlation was found between femoral anteversion and stem anteversion in both the supine and lateral groups (r = 0.68, p < 0.0001 and r = 0.52, p < 0.0001, respectively).

CONCLUSION

Although stem anteversion was more strongly correlated with femoral anteversion in the supine position than in the lateral position, neutral position in the sagittal plane was more likely to be found with the lateral position than with the supine position. Surgeons can achieve ideal stem positioning by considering these results in the modified Watson-Jones approach in both the supine and lateral positions.

Anterior pelvic plane registration accuracy and cup position measurement using ultrasound- and pointer-based navigation in primary total hip arthroplasty

BACKGROUND

Incorrect cup positioning in primary total hip arthroplasty is known as a risk factor for early implant failure. The use of navigation systems leads to more accurate cup positioning.

OBJECTIVE

The aim of this study was to compare the registration accuracy of the anterior pelvic plane and the measurement accuracy of the definite cup position for a pointer computer-assisted orthopaedic navigation system (P-CAOS) and an ultrasound-based navigation tool (US-CAOS) in an intra-individual study design.

METHODS

Anterior pelvic plane registration was performed in 44 patients receiving a primary total hip arthroplasty with P-CAOS and US-CAOS. The cup implantation was performed using US-CAOS. Intraoperatively, the cup position was assessed using P-CAOS and US-CAOS. The postoperative cup position was determined via CT scan. Inclination and anteversion errors were calculated using intraoperative values and CT data. All operations were performed by a single, high-volume surgeon using a minimally invasive anterolateral approach.

RESULTS

The mean inclination error was 0.9∘ in the US-CAOS group and -1.1∘ in the P-CAOS group. This was not statistically significant. The mean anteversion error was significantly reduced (p< 0.001) in the US-CAOS group (1.4∘) compared to the P-CAOS group (-8.0∘). Significantly more cups (23 of 44; 52%) in the P-CAOS group were outliers regarding to the defined anteversion error range of 15∘± 10∘. Outliers in the US-CAOS group amounted to two (of 44; 5%) (p< 0.001). The number of outliers regarding the inclination error range of 40∘± 10∘, did not differ significantly between the P-CAOS (2; 5%) and US-CAOS (1; 2%) group.

CONCLUSION

We were able to show a systematic anterior pelvic plane registration error in this intraindividual study design. US-CAOS based APP landmark registration showed to be significantly more precise compared to P-CAOS registration. The anteversion error of the cup using US-CAOS showed to be significantly reduced compared to the P-CAOS method.

Minimum 10 years clinical results of an anatomical short stem with a proximal hydroxyapatite coating

OBJECTIVES

The CentPillar stem (Stryker Orthopaedics), an anatomical short stem, was designed to match the proximal femoral canal shape in both patients with normal hips and those with developmental dysplasia of the hip (DDH). The long-term outcomes of the CentPillar stem was examined herein.

METHODS

In total, 222 hips that underwent total hip arthroplasty using the CentPillar stem were analyzed. DDH was the main reason for surgery (79.3%). Implant survivorship was assessed using Kaplan-Meier analysis. For radiographic evaluation, stress shielding was assessed using the Engh classification. For functional evaluation, patients' ability to perform deep hip bending activities (sit on the floor, squat, and sit straight) was assessed.

RESULTS

During a median follow-up of 13.1 years, 2 stem revisions were performed (aseptic loosening and late hematogenous periprosthetic infection), and the overall cumulative implant survival rate was 99.0% at 15 years. In the radiographic evaluation, grade >3 stress shielding was found in only one hip. More than 80% of the patients were able to perform each of the three deep hip bending activities.

CONCLUSIONS

Good fixation at the proximal part of the femur was obtained, and the implant survival rate of the CentPillar stem was excellent during a long-term follow-up.

Is a portable accelerometer-based navigation system useful in total hip arthroplasty?: A systematic review and meta-analysis

BACKGROUND

Precise implant alignment is a crucial prognostic factor for successful outcomes following total hip arthroplasty (THA). A portable accelerometer-based navigation (PN) device may achieve the same accuracy as that achieved by the computer-assisted navigation surgery technique, with the convenience of a conventional technique. Although the usefulness of PN in THA (PN-THA) has been reported, whether it is more accurate than performing THA with a conventional technique (CON-THA) remains controversial. The difference in surgical time between PN-THA and CON-THA is also unclear. Therefore, we conducted a systematic review and meta-analysis of studies comparing results of PN-THA with those of CON-THA. We focused on the following question: is PN-THA superior to CON-THA in terms of radiological parameters and surgical time?

PATIENTS AND METHODS

A literature search was conducted in PubMed, Web of Science, and Cochrane Library, to identify studies that met the following inclusion criteria: randomised controlled trials (RCT) or non-RCT, studies involving patients who underwent PN-THA and patients who underwent CON-THA, studies including data on radiological parameters and surgical outcomes. Author names, publication year, country, study design, surgical approach, demographic characteristics of the participants (diagnosis, gender, age, and body mass index), and surgical outcomes (the radiological parameters and the surgical time) were extracted. We calculated the mean differences (MDs) for continuous data with 95% confidence intervals (CIs) for each outcome. p<0.05 was considered significant.

RESULTS

Three studies were included in this meta-analysis. The meta-analysis showed that absolute deviation of the postoperative measured angles from the target position for the cup anteversion was significantly smaller in PN-THA than in CON-THA (MD=-1.70, 95% CI=-2.91 to -0.50, [p=0.005]). There was no significant difference in the absolute deviation of the postoperative measured angles from the target position for cup abduction between the groups (MD=-1.82, 95% CI=-4.32-0.67, [p=0.15]). The surgical time was significantly longer in PN-THA than in CON-THA (MD=8.58, 95% CI=4.05-13.10, [p=0.0002]).

DISCUSSION

This systematic review and meta-analysis of studies comparing the results of PN-THA with those of CON-THA showed that the PN-THA is advantageous for precise cup implantation compared to CON-THA, although PN-THA has a longer surgical time compared to CON-THA.

LEVEL OF EVIDENCE

III.

Impingement Between the Metal Stem and the Ceramic Liner in Total Hip Arthroplasty: The Neck Is Not the Only Place Where Impingement Occurs

BACKGROUND

It is assumed that impingement between the ceramic liner and the stem increases the possibility of a liner fracture in total hip arthroplasty with a ceramic-on-ceramic bearing. The purpose of this study was to analyze the pattern of the impingement by evaluating the notches (U-shaped indented wear scars engraved on the stem) on radiographs to determine when and where impingement develops and to analyze the factors affecting its occurrence.

METHODS

Among the primary total hip arthroplasty cases using a ceramic-on-ceramic bearing performed from November 1997 to December 2003, 244 cases of 197 patients (123 male patients and 74 female patients) that had follow-up of ≥15 years were included. All of the radiographs were examined with special regard to the notches and the cup positions.

RESULTS

Notches were detected at 77 sites of 57 cases (23.4%) for the first time between 8 months and 14.8 years after the surgical procedure. They were located on the neck or the shoulder of the stem. Shoulder notches were detected only in the cases with a short-neck head. Shoulder notches were found in 29 cases (20.0% of short-neck cases). Cup inclination was lower (p = 0.01) and anteversion was higher (p = 0.01) in the group with notches than the group without notches. There were 5 cases of ceramic head fracture. One of them experienced another ceramic liner fracture, assumed to be caused by prosthetic shoulder impingement, after the revision surgical procedure.

CONCLUSIONS

The results of this study suggest that impingement between the stem and the ceramic liner occurs in a considerable proportion of patients who underwent total hip arthroplasty not only on the neck but also on the shoulder of the stem. Forceful and abrupt impingement on the stem shoulder can cause ceramic liner fracture. Impingement between the stem shoulder and the ceramic liner should be considered in designing a stem. It seems to be prudent to recommend that patients avoid squatting or sitting cross-legged on the floor as much as possible.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Impingement Resulting in Femoral Notching and Elevated Metal-Ion Levels After Dual-Mobility Total Hip Arthroplasty

A 60-year-old woman underwent revision total hip arthroplasty with a modular dual-mobility articulation for recurrent dislocation. At 1-year follow-up, the patient reported no dislocations but had occasional clicking and discomfort with extreme motion. A Dunn radiograph identified notching of the femoral stem, attributed to impingement. Metal ions were elevated without adverse local-tissue reaction. After 4.5 years of observation, the notch size remained stable. She denied pain. Neither stem fracture nor prosthetic dislocation occurred. Impingement against cobalt-chromium acetabular bearing surfaces can result in notching of titanium femoral components after total hip arthroplasty. Increased anteversion intended to protect against posterior dislocation may be a risk factor. Posterior notching is best visualized on Dunn views, so incidence may be underestimated. No associated femoral implant fractures were identified on literature review.

Lewinnek Safe Zone References are Frequently Misquoted

BACKGROUND

Optimal acetabular component orientation in total hip arthroplasty (THA) is a necessity in achieving a stable implant. Although there has been considerable debate in the literature concerning the safe zone, to date, there has not been any review to determine if these references are consistent with the definition applied by Lewinnek et al. in 1978. Therefore, this article aims to examine the available literature in the PubMed database to determine how often a correct reference to the safe zone as defined by Lewinnek was applied to discussions regarding THA.

METHODS

A search for literature in the PubMed database was performed for articles from 1978 to 2019. Search criteria included terms 'Lewinnek,' 'safe zone,' and 'total hip arthroplasty.' Exclusions included abstract-only articles, non-English articles, articles unrelated to THA, and those lacking full content.

RESULTS

A review of literature yielded 147 articles for inclusion. Overall, only 11% (17) cited the Lewinnek article correctly. Forty-five percent (66) of articles referenced measurements in the supine position, 18% (26) referenced other positions, and 37% (55) did not specify. Nineteen percent (28) reported measurements of the acetabular cup orthogonal to the anterior pelvic plane, while 73% (108) did not, and 7% (11) did not specify. Twenty-three percent (34) measured from computed tomography scans instead of other methods.

CONCLUSIONS

In the discussion of the safe zone regarding THA, only 11% of articles listed are consistent with the definition established by Lewinnek. This warrants further investigation into a consistent application of the term and its implications for THA implant stability and dislocation rates.

Pelvic motion the key to understanding spine-hip interaction

Pelvic motion acting as a hinge between the spine and hips is essential to maintain proper balance during bipedalism. Pelvic rotation is recruited as a compensation mechanism when spinal malalignment occurs.This pelvic rotation can affect functional acetabular orientation, and consequently functional cup positioning if a total hip arthroplasty (THA) is needed. Pelvic retroversion, frequently associated with degenerative spinal changes, implies an increase of acetabular version.Patients with flexible lumbar spines (spine users) protect the hip joint. Patients with stiff, degenerated or fused lumbar spines (hip users) demand higher hip mobility, placing the THA at risk.Pelvises in retroversion place the THA at risk for anterior dislocation when standing. In contrast, pelvises in anteversion or with low pelvic incidence (PI) can place THA at risk for posterior dislocation when sitting.Try to set the cup in an anatomic position. However, bear in mind that low PI pelvises may need more acetabular ante-inclination, and high PI pelvises more acetabular retroversion.If surgery is needed, start first by addressing the hip, except in patients with compensation (high pelvic retroversion), who may need spine surgery first to place the pelvis, and consequently the acetabulum, in a proper position. Cite this article: EFORT Open Rev 2020;5:522-533. DOI: 10.1302/2058-5241.5.200032.

A review of computer-assisted orthopaedic surgery systems

BACKGROUND

Computer-assisted orthopaedic surgery systems have great potential, but no review has focused on computer-assisted surgery systems for the spine, hip, and knee.

METHODS

A systematic search was performed in Web of Science and PubMed. We searched the literature on computer-assisted orthopaedic surgery systems from 2008 to the present and focused on three aspects of systems: training, planning, and intraoperative navigation.

RESULTS AND DISCUSSION

In this review study, we reviewed 34 surgical training systems, 31 surgical planning systems, and 41 surgical navigation systems. The functions and characteristics of the surgical systems were compared and analysed, and the current concerns about and the impact of the surgical systems on doctors and surgery were clarified.

CONCLUSION

Computer-assisted orthopaedic surgery systems are still in the development stage. Future surgical training systems should include synthetic models with patient anatomy. Surgical planning systems with automatic planning should be developed, and surgical navigation systems with multimodal fusion, robotic assistance and imaging should be developed.

Incidence of Ceramic Fracture in Contemporary Ceramic-on-Ceramic Total Hip Arthroplasty: A Meta-analysis of Proportions

BACKGROUND

We performed a proportion meta-analysis of currently available data to determine the prevalence of ceramic fracture for each generation.

METHODS

A total of 10,571 total hip arthroplasties from 45 studies were included. Proportion meta-analysis with a random-effects model was performed to estimate the prevalence of ceramic fracture. To determine whether the ceramic fractures have a fatigue nature and a risk or latent period for the development, postoperative time lapse, patient age, and body mass index were related with ceramic fracture by metaregression analysis.

RESULTS

As of postoperative 2.0 to 18.8 years, the rate of ceramic fracture was 0.5% (95% CI, 0.3%-0.8%) in the forte group and 0.2% (95% CI, 0.1%-0.4%) in the delta group (P = .059). The ceramic fracture rate for each component was 0.2% (95% CI, 0.1%-0.3%) for the forte head, 0.1% (95% CI, 0.0%-0.2%) for the delta head (P = .210), 0.2% (95% CI, 0.1%-0.3%) for the forte liner, and 0.2% (95% CI, 0.1%-0.4%) for the delta liner (P = .305). The rate of ceramic fracture per 1000 patient-years was 0.9 (95% CI, 0.5-0.13) in the forte group and 0.5 (95% CI, 0.2-0.8) in the delta group (P = .072). In metaregression analysis, no significant associations were found between prevalence of ceramic fracture and postoperative time lapse, patient age, or body mass index.

CONCLUSIONS

The rate of ceramic fracture was 0.9/1000 patient-year in the forte group and 0.5/1000 patient-year in the delta group. The results of this study provide baseline data for further studies validating ceramic bearings.

LEVEL OF EVIDENCE

Level I, meta-analysis.

Outcomes of computer-assisted peri-acetabular osteotomy compared with conventional osteotomy in hip dysplasia

Aim of the study

To compare the outcomes after computer-assisted peri-acetabular osteotomy (PAO) and conventional PAO performed for hip dysplasia (DDH).

Methods

Ninety-one patients (98 hips) were enrolled in this study. In each case, DDH was treated with either conventional PAO, in which the angle and direction of the osteotomy was determined by intra-operative X-ray examination, or with computer-assisted PAO, which used the 3D navigation system. Forty hips underwent conventional PAO and 58 hips underwent computer-assisted PAO.

Results

Japanese Orthopaedic Association hip scores improved significantly from 70.0 points pre-operatively to 90.7 points post-operatively in patients with conventional PAO, and from 74.5 points pre-operatively to 94.2 points post-operatively in patients with computer-assisted PAO. In all patients with computer-assisted PAO, the post-operative AHI and VCA angle were within the radiographic target zone. Some patients with conventional PAO had post-operative AHI and VCA angle outside of the target zone. We performed total hip arthroplasty (THA) on five of the 98 PAO hips (5.1%) after an average follow-up period of 5.4 years. None of 58 hips (0%) with computer-assisted PAO was revised.

Discussion

Computer-assisted PAO enabled intra-operative confirmation of osteotomy sites, and the position of the osteotomized bone fragment could be confirmed in real time. Adequate anterior and lateral coverage of the femoral head in patients with computer-assisted PAO resulted in no need for early conversion to THA, in contrast to conventional PAO.

Conclusion

Computer-assisted PAO not only improved accuracy and safety but also achieved sufficient anterior and lateral displacement to prevent the progression of DDH.

An accelerometer-based navigation system provides acetabular cup orientation accuracy comparable to that of computed tomography-based navigation during total hip arthroplasty in the supine position

Background

Inadequate acetabular component orientation is associated with postoperative impingement, dislocation, and accelerated polyethylene wear. Computed tomography (CT)-based navigation systems provide accuracy for total hip arthroplasty (THA) but are not available in all facilities. Accelerometer-based navigation systems are inexpensive, but their accuracy remains undetermined. This study compares the accuracy of cup orientation in THA using CT-based and accelerometer-based navigation systems.

Methods

This retrospective study included 35 consecutive patients (11 males, 24 females; mean age, 65 years) who underwent primary cementless THA via an anterolateral approach in the supine position. Both CT-based and accelerometer-based navigation systems were used simultaneously. The accuracy of cup orientation was compared between the two systems using postoperative CT.

Results

The accuracy of cup inclination was 2.7° ± 2.0° in the CT-based group and 3.3° ± 2.4° in the accelerometer-based group. The accuracy of cup anteversion was 2.8° ± 2.6° in the CT-based group and 3.4° ± 2.2° in the accelerometer-based group. No significant difference was observed in cup inclination (p = 0.29) or cup anteversion (p = 0.34) between CT-based and accelerometer-based navigation.

Conclusions

The accuracy of cup positioning did not differ significantly between CT-based and accelerometer-based navigation systems.

Accuracy of cup orientation and learning curve of the accelerometer-based portable navigation system for total hip arthroplasty in the supine position

PURPOSE

To assess the accuracy of cup orientation and learning curve of the disposable accelerometer-based portable navigation system for total hip arthroplasty (THA) in the supine position.

METHODS

A total of 75 patients who underwent THA through the anterolateral supine approach (ALS) with an accelerometer-based portable navigation system for the supine position (HipAlign^®) between July 2017 and October 2018 were analyzed in this study. We compared the intraoperative cup angles using navigation records with the postoperative angles using postoperative computed tomography (CT) data. All patients were categorized into the following groups according to the course of three discrete, sequential operative time periods: 1-25 (initial group), 26-50 (intermediate group), and 51-75 (recent group). We compared the accuracy of cup inclination and anteversion among the three groups. The time required for navigation and the operative time of all patients were measured.

RESULTS

The average absolute error in measurement (postoperative CT-navigation record) was 2.6° ± 2.7° (inclination) and 2.8° ± 2.7° (anteversion). There were no significant differences among the three groups. The average time required for navigation and the operative time were 365.1 ± 90.3 s and 76.1 ± 1.6 min, respectively. The required time for HipAlign^® navigation and operative time were constant in most patients, except for those of the initial five cases.

CONCLUSION

The accelerometer-based portable navigation system provides good accuracy of cup orientation, has a short learning curve, and requires a minimal surgical time for THA in supine position.

Applicability of augmented reality in orthopedic surgery - A systematic review

BACKGROUND

Computer-assisted solutions are changing surgical practice continuously. One of the most disruptive technologies among the computer-integrated surgical techniques is Augmented Reality (AR). While Augmented Reality is increasingly used in several medical specialties, its potential benefit in orthopedic surgery is not yet clear. The purpose of this article is to provide a systematic review of the current state of knowledge and the applicability of AR in orthopedic surgery.

METHODS

A systematic review of the current literature was performed to find the state of knowledge and applicability of AR in Orthopedic surgery. A systematic search of the following three databases was performed: "PubMed", "Cochrane Library" and "Web of Science". The systematic review followed the Preferred Reporting Items on Systematic Reviews and Meta-analysis (PRISMA) guidelines and it has been published and registered in the international prospective register of systematic reviews (PROSPERO).

RESULTS

31 studies and reports are included and classified into the following categories: Instrument / Implant Placement, Osteotomies, Tumor Surgery, Trauma, and Surgical Training and Education. Quality assessment could be performed in 18 studies. Among the clinical studies, there were six case series with an average score of 90% and one case report, which scored 81% according to the Joanna Briggs Institute Critical Appraisal Checklist (JBI CAC). The 11 cadaveric studies scored 81% according to the QUACS scale (Quality Appraisal for Cadaveric Studies).

CONCLUSION

This manuscript provides 1) a summary of the current state of knowledge and research of Augmented Reality in orthopedic surgery presented in the literature, and 2) a discussion by the authors presenting the key remarks required for seamless integration of Augmented Reality in the future surgical practice.

TRIAL REGISTRATION

PROSPERO registration number: CRD42019128569.

Portable imageless navigation system and surgeon's estimate for accurate evaluation of acetabular cup orientation during total hip arthroplasty in supine position

BACKGROUND

This prospective study aimed to clarify whether this novel device can evaluate the cup orientation during total hip arthroplasty (THA) more closely to that measured in postoperative computed tomography (CT) compared to the surgeon's estimate using a manual goniometer.

METHODS

We prospectively performed 30 cementless THAs via the anterolateral approach in supine position between October 2018 and July 2019, wherein cup orientation was evaluated by both a portable imageless navigation system (HipAlign) and a manual goniometer during surgeries. Primary outcome was the absolute estimate error [the absolute value of the difference between cup angles measured by postoperative CT and those measured by HipAlign (group H) or surgeon's estimate using the manual goniometer (group S) during surgery]. The number of outliers of the absolute estimate error (> 10°) in each group was also estimated.

RESULTS

The absolute estimate error of cup inclination in groups H and S was 3.3° ± 2.7° and 3.0° ± 2.5°, respectively (p = 0.51), whereas that of cup anteversion was 3.8° ± 3.4° and 6.0° ± 3.7°, respectively (p = 0.0008). The number of outliers of the estimate error in groups H and S was one case (3.3%) and six cases (20.0%), respectively (p = 0.04). In all six outlier cases, surgeons underestimated cup anteversion during surgeries.

CONCLUSIONS

This portable imageless navigation system was a useful method, especially for avoiding incorrect cup anteversion. Underestimation of cup anteversion during THA in the supine position with the conventional alignment assisting device should be given attention.

Portable Accelerometer-Based Navigation System for Cup Placement of Total Hip Arthroplasty: A Prospective, Randomized, Controlled Study

BACKGROUND

Malposition of the acetabular component during total hip arthroplasty (THA) is associated with increased risk of dislocation, reduced range of motion, and accelerated wear. The purpose of this study is to compare cup positioning with a portable, accelerometer-based hip navigation system and conventional surgical technique.

METHODS

In a prospective, randomized, clinical study, cups were implanted with a portable, accelerometer-based hip navigation system (navigation group; n = 55) or conventional technique (conventional group; n = 55). THA was conducted in the lateral position and through posterior approach. The cup position was determined postoperatively on pelvic radiograph and computed tomography scans.

RESULTS

An average cup abduction of 39.2° ± 4.6° (range, 27° to 50°) and an average cup anteversion of 14.6° ± 6.1° (range, 1° to 27.5°) were found in the navigation group, and an average cup abduction of 42.9° ± 8.0° (range, 23° to 73°) and an average cup anteversion of 11.6° ± 7.7° (range, -12.1° to 25°) in the conventional group. A smaller variation in the navigation group was indicated for cup abduction (P = .001). The deviations from the target cup position were significantly lower in the navigation group (P = .001, .016). While only 37 of 55 cups in the conventional group were inside the Lewinnek safe zone, 51 of 55 cups in the navigation group were placed inside this safe zone (P = .006). The navigation procedure took a mean of 10 minutes longer than the conventional technique.

CONCLUSION

Use of the portable, accelerometer-based hip navigation system can improve cup positioning in THA.

Correlation of tilt of the anterior pelvic plane angle with anatomical pelvic tilt and morphological configuration of the acetabulum in patients with developmental dysplasia of the hip: a cross-sectional study

Background

It was previously reported that pelvises with developmental dysplasia of the hip are tilted anteriorly, which increases bony coverage of the femoral head. This study aimed to investigate the correlation between anatomical parameters of the pelvis such as pelvic incidence and anatomical pelvic tilt and functional parameters of the spine and pelvis such as tilt of the anterior pelvic plane.

Methods

We examined 84 female patients with bilateral developmental dysplasia of the hip who had undergone curved periacetabular osteotomy at author’s institution. Radiographs of the thoracic to lumbar spines and the pelvis were obtained in the standing position to measure spino-pelvic parameters before surgery. Morphological parameters of the acetabulum such as the anterior center-edge (CE) angle, posterior CE angle, lateral CE angle, and acetabular anteversion were measured using a preoperative three-dimensional pelvic model reconstructed from computed tomography images. Pearson’s correlation analysis was conducted to evaluate the relationship of these parameters.

Results

With regard to correlations between pelvic incidence (PI) and other parameters, the sacral slope (SS) value (r = 0.666) was the highest among functional parameters and the anatomical-SS value (r = 0.789) was the highest among morphological parameters. There were moderate correlations of the anterior pelvic plane angle (APPA) with pelvic tilt (PT) (r = − 0.594) and anatomical-PT (r = 0.646). With regard to correlations between spino-pelvic parameters and bony morphological parameters of the acetabulum, there was a moderate correlation between anatomical-PT and acetabular anteversion (AA) (r = 0.424). There were moderate correlations of APPA with the anterior CE angle (r = − 0.478), posterior CE angle (r = 0.432), and AA (r = 0.565). APPA had a stronger correlation with anatomical-PT (r = 0.646) than with AA.

Conclusions

The tilt of the pelvis may be more dependent on anatomical-PT, a morphological parameter of the pelvis, than the lateral CE angle, anterior CE angle, posterior CE angle, and acetabular anteversion on bony coverage of the acetabulum. This study is the first to investigate the correlation between functional parameters of the pelvis and spine and morphological parameters of the pelvis and acetabulum besides PI.

Is the alignment guide technique in total hip arthroplasty sufficient for accurate cup positioning with a modified Watson Jones approach?

PURPOSE:

Cup setting with only an alignment guide has been reported to be inaccurate in the lateral decubitus position in total hip arthroplasty (THA). We assessed the accuracy of cup positioning using only the alignment guide technique via a modified Watson Jones approach in the lateral decubitus position.

METHODS:

Two hundred hips of 189 patients underwent THA from October 2014 to September 2016 via a modified Watson Jones approach. In the final sample, 181 hips of 171 patients (35 males, 136 females) were included in this investigation. The alignment of the cup was evaluated by an anteroposterior radiograph of the pelvis 1 week after surgery. Measurements were divided into safe zone determined by Callanan and Lewinnek.

RESULTS:

There were 168 (92.8%) acetabular cups that were placed within the safe zone for both inclination and anteversion based on the safe zones defined by Lewinnek, and 134 (74%) acetabular cups that were placed within the safe zone defined by Callanan. Multiple logistic analysis showed that the laterality and the addition of the confirmation method were indicators for malpositioning of combined inclination and anteversion.

CONCLUSION:

Our data suggested that even if special tools were not used in the lateral decubitus position, using only the alignment guide enabled cup positioning to be achieved with 92.8% accuracy in the Lewinnek safe zone and 74% accuracy in the Callanan safe zone. Multiple logistic analysis showed that the laterality and the addition of a confirmation alignment guide influenced the accuracy of cup positioning.

Computer Navigation vs Conventional Total Hip Arthroplasty: A Medicare Database Analysis

BACKGROUND

Computer-assisted surgery (CAS) is applied to total hip arthroplasty (THA) in an attempt to optimize implant positioning. The effect of CAS on postoperative complications after THA remains unknown. Our study aims to assess the change in complication rates when CAS is used in THA.

METHODS

The Medicare database was studied from 2005 to 2012. All THAs performed with CAS were identified. A total of 64,944 THAs were identified, including 5412 CAS-THAs and 59,532 conventional THAs. Medical and surgical adverse events were collected at various time points.

RESULTS

CAS-THA was not associated with a decreased rate of dislocation at 30 days (1.0% vs 1.2%; odds ratio [OR], 1.14; P = .310), 90 days (1.1% vs 1.4%; OR, 1.23; P = .090), or 2 years (2.3% vs 2.3%; OR, 1.01; P = .931). CAS-THA was associated with a significantly higher rate of periprosthetic fracture at 30 days (0.4% vs 0.6%; OR, 1.46; P = .040) as well as revision THA at 30 days (1.0% vs 1.4%; OR, 1.43; P = .003) and 90 days (1.2% vs 1.7%; OR, 1.42; P < .002) when compared to conventional THA. CAS-THA was associated with a significantly lower rate of deep vein thrombosis and pulmonary embolism when compared to conventional THA at all time points (P < .05).

CONCLUSION

Administrative coding data fail to demonstrate any clinically significant reduction in short-term adverse events with CAS-THA. Further study is warranted to evaluate whether the purported benefits of CAS result in a reduction of the adverse events after THA.

Supine versus lateral position for accurate positioning of acetabular cup in total hip arthroplasty using the modified Watson-Jones approach: A randomized single-blind controlled trial

BACKGROUND

The orientation of the acetabular cup is a critical factor for prevention of various postoperative complications in total hip arthroplasty (THA). Although most patients are treated in either supine or lateral position during surgery, it is still unclear which position is superior to achieve more accurate cup positioning. Our study was conducted in order to answer the following questions: (1) does the supine position provide a higher accuracy of cup positioning than the lateral position in THA using modified Watson-Jones approach? (2) is there any difference in the distribution of cup position between the two positions? Hypothesis Our hypothesis was that the supine position would provide a higher accuracy of cup positioning than the lateral position in THA using modified Watson-Jones approach.

PATIENTS AND METHODS

A single-center prospective randomized study (registration number: UMIN000021627) was conducted between May 2016 and December 2017. We recruited a total of 60 participants undergoing unilateral primary cementless THA using modified Watson-Jones anterolateral approach based on the result of the sample size calculation. They were randomly assigned to either supine position (n=29) or lateral position (n=31). The cup alignment was targeted using a goniometer during surgery. The radiographic cup inclination was targeted to 40° and the radiographic cup anteversion was targeted considering the femoral stem anteversion during surgery. Postoperative cup alignment was measured by plain radiography and computed tomography. We defined the difference between postoperative and target cup angle as target error and our primary outcome was the absolute value of the target angle. As secondary outcome, the distribution of the target error was evaluated. The target errors of each inclination and anteversion were divided into 3 groups; neutral (-3°≤the target error≤3°), positive error (3°<the target error), and negative error (the target error<-3°).

RESULTS

The assessment of primary outcome for all recruited patients showed that supine group was significantly more accurate than lateral group in terms of radiographic inclination (2.4° vs. 4.5°, respectively, mean difference 2.1°; 95% confidence interval, 0.7 to 3.5; p<0.01). There was no significant difference in terms of radiographic cup anteversion (5.6° vs. 5.2°, mean difference 0.4°; 95% confidence interval, -1.8 to 2.6; p=0.69). The rate of positive error of anteversion in supine and lateral group was larger than that of negative value of anteversion (51.7% vs. 10.3% and 48.4% vs. 12.9%, respectively). Any acute complication (dislocation, fracture, and infection) was not found in both groups during postoperative 3 months.

DISCUSSION

In this randomized-controlled trial, higher accuracy of acetabular cup inclination was provided by supine position than by lateral position in THA. On the other hand, there was no significant difference between both groups in terms of cup anteversion. In both groups, most cups were placed with larger anteversion than we targeted. Modified Watson-Jones approach in both positions should be performed considering these results.

STUDY REGISTRATION NUMBER

UMIN000021627. Level of evidence II, randomised controlled study (population-limited).

Accuracy of acetabular cup placement using CT-based navigation in total hip arthroplasty: Comparison between obese and non-obese patients

BACKGROUND

In obese patients, malpositioning of the acetabular cup increases the risk of dislocation in total hip arthroplasty (THA). The aim of this study was to determine whether obesity affects the accuracy of acetabular cup positioning using a computed tomography (CT)-based navigation system.

METHODS

We retrospectively evaluated 226 consecutive patients who underwent cementless primary THAs assisted by the CT-based hip navigation system. We divided the patients into three groups according to body mass index (BMI) and examined the difference between preoperative planning and postoperative implantation angles from CT data.

RESULTS

There was no significant correlation between BMI and both inclination and anteversion differences (R = 0.028 and R = 0.045, respectively). There were no significant differences among the BMI < 25, 25 ≦ BMI < 30, and BMI ≧ 30 groups (p value: 0.725, 0.934, respectively); between the BMI < 25 and BMI ≧ 25 groups (p value: 0.542, 0.697, respectively); and between the BMI < 30 and BMI ≧ 30 groups with regard to inclination and anteversion (p value: 0.859, 0.456, respectively). Moreover, similar findings were observed with regard to the distance between the preoperative planning and postoperative cup positioning for the transverse, anteroposterior, and craniocaudal axes of the pelvis.

CONCLUSION

We found that the accuracy of acetabular cup placement using CT based-navigation in THA was not affected in obese patients. Therefore, THAs with a CT-based navigation system are considered useful in obese patients.

Longer Operative Time Results in a Higher Rate of Subsequent Periprosthetic Joint Infection in Patients Undergoing Primary Joint Arthroplasty

BACKGROUND

Whether prolonged operative time is an independent risk factor for subsequent surgical site infection (SSI) and periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) remains a clinically significant and underexplored issue. The aim of this study is to investigate the association between operative time and the risk of subsequent SSI and PJI in patients undergoing primary TJA.

METHODS

We retrospectively reviewed 17,342 primary unilateral total knee arthroplasty and total hip arthroplasty performed at a single institution between 2005 and 2016, with a minimum follow-up of 1 year. A multivariate logistic regression model was conducted to identify the association between operative time and the development of SSI within 90 days and PJI within 1 year.

RESULTS

Overall, the incidence of 90-day SSI and 1-year PJI was 1.2% and 0.8%, respectively. Patients with an operative time of >90 minutes had a significantly higher incidence of SSI and PJI (2.1% and 1.4%, respectively) compared to cases lasting between 60 and 90 minutes (1.1% and 0.7%), and those lasting ≤60 minutes (0.9% and 0.7%, P < .01). In the multivariate model, the risk for infection increased by an odds ratio of 1.346 (95% confidential interval 1.114-1.627) for 90-day SSI and 1.253 (95% confidential interval 1.060-1.481) for 1-year PJI for each 20-minute increase in operative time.

CONCLUSION

In patients undergoing primary TJA, each 20-minute increase in operative time was associated with nearly a 25% increased risk of subsequent PJI. We advocate that surgeons pay close attention to this underappreciated risk factor while maintaining safe operative practices, which minimize unnecessary steps and wasted time in the operating room.

Variations in sagittal and coronal stem tilt and their impact on prosthetic impingement in total hip arthroplasty

Optimization of the combined anteversion of cup and stem has been emphasized to avoid prosthetic impingement in total hip arthroplasty (THA). However, no study has focused on the impact of variations in sagittal and coronal stem tilt against the whole femur on prosthetic range of motion. The purposes of the present study were a) to quantify the anatomical variation of sagittal and coronal tilt of the proximal canal axis against the femoral retrocondylar coordinate system, that is variation of sagittal and coronal stem tilt and b) to determine their impact on the zone of impingement-free cup position using computer simulation. Preoperative computed tomography images of 477 femurs from 409 consecutive patients who underwent THA using computed tomography-based computer navigation were stored. Virtual implantation of an anatomical stem was performed on the navigation workstation. The safe zone of the cup position with regard to prosthetic impingement was determined by motion simulation in the range of sagittal and coronal stem tilt of the subjects. The sagittal and coronal stem tilt varied by 10°, which was smaller than the stem anteversion variation. However, there was about 3 times the difference in the impingement-free zone of cup position in the ranges of sagittal and coronal stem tilt. The safe zone was significantly decreased by posterior tilt and valgus tilt of the stem. Range of motion simulation revealed that the variations in sagittal or coronal stem tilt significantly influenced the safe zone of the cup. In conclusion, although the variations in sagittal and coronal stem tilt against the femoral retrocondylar coordinate system were small, their impact on prosthetic impingement was significant.

Minimal Increase in Total Hip Arthroplasty Surgical Procedural Time with the Use of a Novel Surgical Navigation Tool

Background

Computer-assisted navigation has proven effective at improving the accuracy of component placement during Total Hip Arthroplasty (THA); however, the material costs, line-of-site issues and potential for significant time increases have limited their widespread use.

Objective

The purpose of this study was to investigate the impact of an imageless navigation device on surgical time, when compared with standard mechanical guides.

Methods

We retrospectively reviewed prospectively collected data from 61 consecutive primary unilateral THA cases (posterior approach) performed by a single surgeon. Procedural time (incision to closure) for THA performed with (intervention) or without (control) a computer-assisted navigation system was compared. In the intervention group, the additional time associated with the use of the device was recorded. Mean times were compared using independent samples t-tests with statistical significance set a priori at p<0.05.

Results

There was no statistically significant difference between procedural time in the intervention and control groups (102.3±28.3 mins vs. 99.1±14.7 mins, p=0.60). The installation and use of the navigation device accounted for an average of 2.9 mins (SD: 1.6) per procedure, of which device-related setup performed prior to skin incision accounted for 1.1 mins (SD: 1.1) and intra-operative tasks accounted for 1.6 mins (SD: 1.2).

Conclusion

In this series of 61 consecutive THAs performed by a single surgeon, the set-up and hands-on utilization of a novel surgical navigation tool required an additional 2.9 minutes per case. We suggest that the intraoperative benefits of this novel computer-assisted navigation platform outweigh the minimal operative time spent using this technology.

Differences in activities of daily living after hip arthroplasty among hip resurfacing, anterolateral THA, and posterolateral THA: a propensity score matched analysis

The aim was to elucidate the differences in activities of daily living (ADL) after hip arthroplasty among hip resurfacing (HRA), anterolateral total hip arthroplasty (AL-THA), and posterolateral THA (PL-THA) patients after age, sex, body mass index, bilateral/unilateral hip arthroplasty, and postoperative duration were matched using propensity scores. A total of 673 hips from 540 consecutive patients who underwent hip arthroplasty were included. A self-completed questionnaire on preoperative and postoperative ADLs was administered during postsurgical visits at least ≥ 4 years postoperatively. Between HRA and PL-THA patients, the numbers of patients who performed heels-down squatting was significantly more in HRA than in PL-THA. Between AL-THA and PL-THA patients, there were significant differences in postoperative ADLs including bathing in a bathtub, riding on a train/bus, cutting toenails, bowing while straight sitting, heels-up/down squatting, riding on a bicycle, driving a car, and domestic travel. There were no significant differences in postoperative ADLs between ≥ 36 mm head and ≤ 32 mm head PL-THA patients, and between AL-THA and HRA patients. This propensity score matched study indicated that AL-THA and HRA patients were more active postoperatively than PL-THA patients.

Imageless navigation total hip arthroplasty - an evaluation of operative time

Introduction: Imageless navigation has been successfully integrated in knee arthroplasty but its effectiveness in total hip arthroplasty (THA) has been debated. It has consistently been shown that navigation adds significant time and cost to the operation. Further, the relative success of traditional hip replacements has impeded the adoption of new techniques.

Methods: We compared the operative time between fifty total hip replacements with and without the use of imageless navigation by a single senior surgeon in a retrospective study. We employed standard statistical tools to compare the two methods. A correlation-based analysis was used to delimit the “learned” phase of imageless navigation to make comparisons meaningful.

Results: Contrary to what has previously been reported, there was no significant difference between operative time in navigated, when compared to traditional operations (p = 0.498). Only fourteen operations were required to delimit the learning phase of this operation.

Discussion: This is the first study that demonstrates no added operative time when using imageless navigation in THA, achieved with an improved workflow. The results also demonstrate a very reasonable learning curve.

Can Anatomic Measurements of Stem Anteversion Angle Be Considered as the Functional Anteversion Angle?

BACKGROUND

Stem anteversion angle is important in the combined anteversion theory to avoid implant impingement after total hip arthroplasty (THA). However, anatomic measurements of stem anteversion angle may not represent functional anteversion of the femur if the femur undergoes axial rotation. Herein, the femoral rotational angle (FRA) was measured in supine and standing positions before and after THA to evaluate the difference between anatomic and functional measurements.

METHODS

A total of 191 hips (174 patients) treated with THA for osteoarthritis were analyzed in this retrospective, case-controlled study. The FRA was measured as the angle between the posterior condylar line and the line through the bilateral anterior superior iliac spines (positive for external rotation) and was measured preoperatively and postoperatively in supine and standing positions with computed tomography segmentation and landmark localization of the pelvis and the femur followed by intensity-based 2D-3D registration. The number of cases in which the absolute FRA remained <15° in both positions was also calculated.

RESULTS

The average ± standard deviation preoperative FRA was 0.3° ± 8.3° in the supine position and -4.5° ± 8.8° during standing; the postoperative FRA was -3.8° ± 9.0° in supine and -14.3° ± 8.3° during standing. There were 134 cases (70%) in which the preoperative absolute FRA remained <15° in both positions while only 85 hips (45%) remained <15°, postoperatively.

CONCLUSION

Substantial variability was seen in the FRA, especially during the postoperative period. These results suggest that the anatomic stem anteversion angle may not represent the functional anteversion of the femur.

A new system of computer-assisted navigation leading to reduction in operating time in uncemented total hip replacement in a matched population

Computer-assisted navigation techniques are used to optimise component placement and alignment in total hip replacement. It has developed in the last 10 years but despite its advantages only 0.3% of all total hip replacements in England and Wales are done using computer navigation. One of the reasons for this is that computer-assisted technology increases operative time. A new method of pelvic registration has been developed without the need to register the anterior pelvic plane (BrainLab hip 6.0) which has shown to improve the accuracy of THR. The purpose of this study was to find out if the new method reduces the operating time. This was a retrospective analysis of comparing operating time in computer navigated primary uncemented total hip replacement using two methods of registration. Group 1 included 128 cases that were performed using BrainLab versions 2.1-5.1. This version relied on the acquisition of the anterior pelvic plane for registration. Group 2 included 128 cases that were performed using the newest navigation software, BrainLab hip 6.0 (registration possible with the patient in the lateral decubitus position). The operating time was 65.79 (40-98) minutes using the old method of registration and was 50.87 (33-74) minutes using the new method of registration. This difference was statistically significant. The body mass index (BMI) was comparable in both groups. The study supports the use of new method of registration in improving the operating time in computer navigated primary uncemented total hip replacements.

Direct Anterior Approach Using Navigation Improves Accuracy of Cup Position Compared to Conventional Posterior Approach

The accuracy of cup position in total hip arthroplasty is essential for a satisfactory result as malpositioning increases the risk of complications including dislocation, high wear rate, loosening, squeaking, edge loading, impingement and ultimately failure.

We studied 166 patients in a single-surgeon-series of matched cohorts of patients who underwent total hip arthroplasties. Four separate groups were identified comprising of the posterior approach +/- navigation and the direct anterior approach +/- navigation.

We found a significant difference between the direct anterior navigated group and the posterior non-navigated group for both anteversions (P < 0.05, confidence interval (CI) -3.86 to -1.73) and inclination (P < 0.05, CI -3.08 to -1.08). Almost, 72% of anterior navigated patients fell within 5^o of the navigation software set target cup position of 45^o inclination and 20^o anteversion and 100% were within 10^o. Only 30% of posterior non-navigated were within 5^o of both anteversion and inclination and 73% were within 10^o.

There was also a significant difference between the direct anterior navigated and non-navigated group with respect to anteversion only (p < 0.05, CI 1.50 to 1.30). There were no other significant differences between approaches +/- navigation.

The direct anterior approach allows ease of access to both anterior-superior iliac spines for navigation and a supine patient allows anteversion and inclination to be measured in the frontal plane. We conclude that the direct anterior approach with navigation improves the accuracy of cup position compared to the conventional posterior approach without navigation.

Computer navigation of the acetabular component in total hip arthroplasty: a narrative review

Total hip arthroplasty (THA) is a common procedure for primary osteoarthritis, but increasing numbers are also being performed for other pathologies such as secondary arthritis, inflammatory arthropathies and trauma. Estimates suggest that around 8.5 million people in the UK are affected by joint pain secondary to arthritis and a rising ageing population has resulted in an increase in THA operations of around 4% per year over the last six years.

Multiple studies have shown that THA provides improved quality of life scores, but there remains the burden of complications which account for 15% of £1bn NHS liability payouts. DaPalma et al analysed the financial impact of complications following THA and found the additional cost of a dislocation within six weeks of surgery is 342% of the primary cost.

Following primary THA, complications may occur as a result of incorrect component positioning of the femoral stem, the acetabular cup or both. It is known that acetabular malposition may lead to increased rates of dislocation, impingement, edge-loading, polyethylene wear, pelvic osteolysis and prosthesis failure.

Acetabular component positioning has been described as the single most important factor in dictating risk of dislocation following THA. Furthermore, instability and dislocation after primary THA is the most common single reason for revision surgery accounting for 22.5% of all revisions and 33% of acetabular revisions.

We outline the currently available methods of acetabular navigation comparing freehand techniques with computer and robotic-assisted navigation of the acetabular component.

Cite this article: Davenport D, Kavarthapu V. Computer navigation of the acetabular component in total hip arthroplasty: a narrative review. EFORT Open Rev 2016;1:279-285. DOI: 10.1302/2058-5241.1.000050.

What do we get from navigation in primary THA?

Navigation in primary total hip arthroplasty has a history of over 20 years. During this process, imageless computer navigation can be particularly helpful in optimally restoring the hip’s biomechanics. This involves the accurate placement of the acetabular component with the determination of the anteversion and abduction, whereby the navigated femur-first technique also allows for a calculation of the combined anteversion. Additional critical parameters such as the reconstruction of the rotation centre, as well as the femoral and acetabular offset, can also be optimally adjusted. Last but not least, an intra-operative evaluation and equalisation of the leg length is possible.

Nonetheless, the disadvantages of this surgical technique in terms of the high costs in the acquisition and preservation of the necessary devices, as well as the longer operation time, must be taken into account. However, economic aspects are not the only thing preventing widespread use of the navigation technique. Determining the plane of reference (APP) for the optimal orientation of the implants is based on palpation of the bony landmarks – and this is influenced by the thickness of the soft tissue layer. Furthermore, the experience of the surgeon constitutes a variable that influences the accuracy of navigation.

In summary, hip navigation certainly offers an interesting technique for the optimisation of total hip arthroplasty with reconstruction of proper biomechanics. At the same time, there is currently a lack of high-quality randomised controlled long-term trials that evaluate the clinical advantage for the patients, together with cost utility and survival rates.

Cite this article: Renner L, Janz V, Perka C, Wassilew GI. What do we get from navigation in primary THA? EFORT Open Rev 2016;1:205-210. 10.1302/2058-5241.1.000034.