Does Intraoperative Fluoroscopy Improve Limb-Length Discrepancy and Acetabular Component Positioning During Direct Anterior Total Hip Arthroplasty?

Does the utilization of fluoroscopy affect the accuracy of prosthesis position in patients undergoing hip replacement surgery via the direct anterior approach compared to the posterolateral approach for an experienced surgeon? A single-center retrospective study

BACKGROUND

The direct anterior approach (DAA) for total hip arthroplasty (THA) has gained popularity due to perceived advantages in achieving better early outcomes. However, the theoretical benefits such as precise implant positioning and accurate leg length restoration are still inconsistent. In this study, we compared implant position and leg length discrepancy (LLD) of the DAA and posterolateral approach (PLA) conducted by a single surgeon who had mastered both approaches.

METHODS

This study retrospectively reviewed the medical records and radiographic images of 244 patients who underwent THA between 2012 and 2021 by a single experienced surgeon using either the DAA (n = 120) or PLA (n = 124). Postoperative pelvic anteroposterior radiographs at 6 months follow-up were used to assess acetabular component inclination and anteversion, as well as LLD. Mann-Whitney U tests and Chi-squared test were performed to compare outcomes between the two approaches.

RESULTS

No significant differences were observed in patient demographics between the two groups. The DAA group demonstrated significantly lower postoperative LLD (0.00 mm) compared to the PLA group (5.00 mm, p < 0.0001). No significant difference was observed in the Lewinnek zone for cup anteversion and inclination angles between the two groups.

CONCLUSIONS

For experienced surgeons in other approaches, our findings suggest transferring to the DAA may not substantially improve cup positioning, but it might slightly enhance limb length measurement. For surgeons already proficient in other approaches and deciding to maintain those approaches, their primary concern for optimal THA outcome should be striving for leg length equivalence.

Leg Length Discrepancy in Total Hip Arthroplasty: Not All Discrepancies Are Created Equal

The original review article, published in 2006, describing leg length discrepancy after total hip arthroplasty commented that "equal leg length should not be guaranteed." There has been considerable advancement in surgical technique and technology over the past decade, allowing surgeons to "hit the target" much more consistently. In this interval paper, we review leg length discrepancy and introduce some technologies designed to mitigate this complication. In addition, we present challenging clinical scenarios in which perceived leg length may differ from true leg length and how these can be addressed with proper workup and surgical execution.

The effect of intraoperative fluoroscopy on acetabular component positioning and patient anatomy restoration during total hip arthroplasty: A systematic review and meta-analysis

BACKGROUND

In total hip arthroplasty (THA), the positioning of components holds critical importance for factors such as joint stability, polyethylene liner wear, and range of motion. This meta-analysis aimed to compare the effects of intraoperative fluoroscopy (IF) versus no use of IF on component positioning and the restoration of patient anatomy during THA.

METHODS

We conducted our systematic review following the recommendations outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. The literature search was performed from the inception of medical databases up to August 2023. PubMed, Embase, Web of Science, Cochrane Controlled Trials Register, Cochrane Library, Highwire, Wanfang, China National Knowledge Infrastructure (CNKI), China Biology Medicine Disc (CBM), and China Science and Technology Journal (CSTD) databases were systematically searched to identify relevant studies comparing IF versus no IF during primary THA.

RESULTS

Thirteen studies involving 2195 patients (2207 hips) were incorporated in the Analysis. No statistically significant differences were observed between the groups in terms of acetabular cup inclination angle (ACIA, P = .9), ACIA within the safe zone rate (P = .87), acetabular cup anteversion angle (ACAA, P = .42), ACAA within the safe zone rate (P = .35), combined safe zone rate (P = .30), limb length difference (LLD, P = .13), dislocation rate (P = .76), and infection rate (P = .97). In comparison to the no fluoroscopy group, the IF group exhibited prolonged operation time (P < .00001) and reduced femoral component offset difference (FCOD, P = .03).

CONCLUSION

IF did not demonstrate improvements in acetabular cup placement, limb length difference, or dislocation occurrence. Nonetheless, IF showed a significant enhancement in restoring femoral offset. It is noteworthy that surgeons operating in facilities with lower patient volumes may observe more pronounced benefits from IF.

Does Artificial Intelligence Outperform Humans Using Fluoroscopic-Assisted Computer Navigation for Total Hip Arthroplasty?

Background

Successful total hip arthroplasty (THA) relies on the correct implant position. THA accuracy can be improved with the use of intraoperative fluoroscopic-assisted computer navigation. Artificial intelligence (AI) software may enhance fluoroscopic navigation; however, the accuracy of the AI compared to human-controlled software in assessing acetabular component position and leg length discrepancy (LLD) has not been studied.

Methods

We analyzed 420 consecutive primary THAs performed by a single surgeon using fluoroscopic-assisted computer navigation software. The first cohort of 211 patients required inputs from a human technician (manual), while the second cohort of 209 patients used an automated version of the software controlled by AI. The intraoperative acetabular component placement (inclination and anteversion) and LLD were recorded and compared to the 2-week postoperative standing anterior-posterior pelvis radiograph.

Results

Ninety-four percent (199/211) of cups in the manual cohort and 95% (198/209) of cups in the AI cohort were within the Lewinnek "safe-zone" (P = 1.0). In the manual cohort, 69% (146/211) of THAs had a final LLD within ±2 mm of the intraoperatively navigated LLD (ie, ΔLLD ≤2 mm). In the AI cohort, 66% (137/209) of THAs had a final LLD within ±2 mm of the intraoperatively navigated LLD (P = .47). Ninety-nine percent (209/211) of hips in the manual cohort and 98% (205/209) of hips in the AI cohort had a final LLD within ±5 mm of the intraoperatively navigated LLD (P = .45).

Conclusions

Both AI and human-controlled versions of the same navigation platform were similarly accurate for navigating cup position within the Lewinnek "safe zone" and LLD accuracy.

An Intraoperative Method to Minimize Leg Length Discrepancy in Anterior Minimally Invasive Total Hip Arthroplasty-A Prospective Study

While several intraoperative devices have been described in the literature for assessing leg length discrepancy (LLD), none have been utilized during total hip arthroplasty (THA) performed via the Anterior Minimally Invasive Surgery (AMIS) approach. The aim of this prospective study was to evaluate the efficacy and accuracy of a compass device in assessing leg length during THA performed using the AMIS technique. A prospective study was conducted involving 35 patients who consecutively underwent unilateral primary THA using the AMIS technique at our department from September 2017 to December 2018. LLD was measured by comparing preoperative and postoperative anteroposterior radiographs of the pelvis, independently assessed by two observers. The mean preoperative LLD was 3.6 (SD 3.9, range, 0.2-19.3) mm. The mean postoperative LLD was 2.5 (SD 3.0, range, 0-12.2) mm. A postoperative LLD of less than 5 mm was observed in 88.2% of cases, with 94.1% having values less than 10 mm. In conclusion, the compass device emerged as a valuable tool for ensuring precise limb length control in THA with the AMIS approach, offering both efficiency and cost-effectiveness in clinical practice.

Fluoroscopy Versus Imageless Optical Navigation in Direct Anterior Approach Total Hip Arthroplasty

BACKGROUND

Utilization of the direct anterior approach (DAA) for total hip arthroplasty (THA) has risen in popularity. Accurate implant placement is a critical factor that influences patient outcomes. The goal of this study was to compare the accuracy and precision of fluoroscopy with imageless optical navigation in DAA THA.

METHODS

This was a cohort study of 640 consecutive primary DAA THAs performed with intraoperative fluoroscopy (n = 300 patients) or imageless optical navigation (n = 304 patients). Accuracy was compared by measuring acetabular cup inclination, anteversion, and leg-length discrepancy (LLD). The proportion of implants placed within the Lewinnek safe zone and those placed within a more precise target of 40 ± 5° inclination and 20 ± 5° anteversion was evaluated.

RESULTS

According to the Lewinnek criteria, there was no difference in the percentage of implants placed within both inclination and anteversion targets (fluoroscopy: 90.3%; navigation: 88.8%, P = 0.519). Using the more precise targets, navigation increased the implants positioned correctly for both inclination and anteversion (fluoroscopy: 50.3%; navigation: 65.6%, P < 0.001). Navigation increased the proportion of implants positioned within the target anteversion zone (fluoroscopy: 71.3%; navigation: 83.8%, P < 0.001) but not inclination (fluoroscopy: 71.9%; navigation: 76.9%, P = 0.147). The mean LLD was higher with the use of fluoroscopy compared with navigation (5.5 mm, standard deviation: 4.1; 4.6 mm, SD: 3.4, P < 0.005). No difference in dislocation rate was observed ( P = 0.643).

CONCLUSION

Both fluoroscopy and imageless optical navigation demonstrated accurate acetabular implant positioning during DAA THA. Navigation was more precise and associated with improved acetabular anteversion placement and restoration of LLD. Navigation is an accurate alternative to fluoroscopy with decreased radiation exposure.

Optimization of Acetabular Cup Abduction by Adjusting Pelvic Pitch

Background

The purposes of this study were to determine the accuracy of our cup positioning method and to evaluate the dislocation rate after total hip arthroplasty (THA).

Methods

After positioning the patient in the lateral decubitus position on the operation table, an anteroposterior view of the hip was taken. The pelvic pitch was measured on the X-ray. A positive pitch was defined as the caudal rotation of the upper hemipelvis. Our target abduction of the cup was 43°. We used the cup holder to guesstimate the cup abduction. In a preliminary study, we found that the weight of the cup holder increased the pelvic pitch by 5°. Thus, the target abduction of the cup holder was calculated by a formula: 43° - pelvic pitch - 5°. During the cup insertion, the cup holder was anteverted to the calculated target according to the concept of combined anteversion. We evaluated 478 THAs (429 patients), which were done with the use of the method.

Results

The mean cup abduction was 43.9° (range, 32.0°-53.0°) and the mean error of cup abduction was 2.4° (standard deviation [SD], 2.0°; range, 0.0°-11.0°). The mean cup anteversion was 28.5° (range, 10.0°-42.0°) and the mean error of cup anteversion was 6.7° (SD, 5.2°; range, 0.0°-27.6°). Of all, 82.4% of the cups (394 / 478) were within the safe zone: 30°-50° abduction and 10°-35° anteversion. During 2- to 5-year follow-up, no hip dislocated.

Conclusions

Our adjusting method according to the pelvic pitch can be a reliable option for optimizing the cup abduction in THA.

The impact of operative approach and intraoperative imaging on leg length discrepancy and acetabular component angle in total hip arthroplasty: a retrospective cohort study

PURPOSE

Operative approach in total hip arthroplasty (THA) has long been a topic of debate with each approach having unique benefits and disadvantages. One purported benefit of an anterior approach to THA is that it allows for intraoperative positioning using fluoroscopy rather than manual positioning. Proper positioning allows for improved outcomes including leg length discrepancy and acetabular component angle. This study aims to examine if operative approach and use of imaging in intraoperative positioning impact LLD and cup angle post-operatively.

METHODS

A total of 300 hips were enrolled in the study with 100 hips per approach (anterior with fluoroscopy, lateral, and posterior). Retrospective chart review was conducted to assess patient demographics and radiographic analysis used to determine LLD and acetabular cup angle.

RESULTS

Of the three groups, those receiving anterior approach THAs were on average older than those in the posterior group. Analysis comparing the LLD and acetabular angle across the three groups showed no statistically significant difference in LLD (p=0.091); this was also reflected when comparing hips that received fluoroscopy with those that did not (p=0.91). For acetabular angle, while no difference existed when comparing hips that received imaging versus those that did not, statistically significant differences were observed when comparing the three intraoperative approaches (p<0.0001).

CONCLUSIONS

Neither intraoperative approach nor the use of intraoperative imaging in THA has a statistically significant effect on LLD post-operatively. However, approach did impact the acetabular cup angle across all three distinct approaches.

Fluoroscopy-guided direct anterior approach total hip arthroplasty provides more accurate component positions in the supine position than in the lateral position

PURPOSE

The position of the acetabular and femoral components is critical for stability and wear resistance. The aim of this study is to investigate whether the fluoroscopy-guided direct anterior approach in the supine position (S-DAA) is more helpful in improving the position of acetabular and femoral components than the fluoroscopy-guided direct anterior approach in the lateral decubitus position (L-DAA).

METHODS

A retrospective analysis of 76 cases of fluoroscopy-guided direct anterior approach total hip arthroplasty (38 cases in the S-DAA and 38 cases in the L-DAA group) was performed in one hospital from 2019 to 2021. The differences in inclination, anteversion, femoral offset (FO), global offset (GO), and leg length discrepancy (LLD) measurements during and after surgery were analyzed. The postoperative femoral offset (FO), global offset (GO), leg length discrepancy (LLD), and preoperative and postoperative Harris hip score were compared between the two groups.

RESULTS

In the S-DAA group, there were no significant differences in the mean intraoperative inclination angle anteversion angle, FO, GO, and LLD compared to the postoperative values, whereas in the L-DAA group, there were significant differences between the intraoperative and postoperative measurements (P < 0.001, P = 0.009, P＜0.001, P＜0.001 and P = 0.008, respectively). Additionally, there were significant differences in the accuracy of LLD, FO, and GO between the two groups (P < 0.001). Compared with the L-DAA group, the average differences of inclination, anteversion, LLD, FO, and GO during and after operation in the S-DAA group were smaller, and the consistency was higher. There was a significant difference in Harris hip score between the two groups at 1 week after surgery (P = 0.033). There was no significant difference in Harris hip score between 1 month and 3 months after surgery (P = 0.482 and P = 0.797, respectively).

CONCLUSIONS

In the supine group, the direct anterior approach (DAA) provides more accurate positioning of the acetabular and femoral components. However, there was no significant difference in hip joint function and activity between the two groups at follow-up.

Does the use of intraoperative measurement reduce limb length discrepancies after total hip arthroplasty?

PURPOSE

Postoperative limb length discrepancy (LLD) is a common complication of total hip arthroplasty, and several methods exist to prevent LLD, but each has its benefits and drawbacks. The study investigates the application of intraoperative lower limb length measurement in preventing postoperative LLD.

METHODS

This study retrospectively analyzed 70 patients who underwent total hip arthroplasty from October 2018 to July 2022. The length of the lower limb on the operated side was measured intraoperatively using a sterilized paper ruler after the fitting of the trial mould and compared with the healthy side. Then the prosthesis size, depth and neck length were adjusted accordingly.

RESULTS

The absolute value of postoperative LLD was found to be 6.68 ± 4.48 mm, of which 53 cases (75.7%) were less than or equal to 10 mm, while 30 patients (42.9%) were less than or equal to 5 mm.

CONCLUSION

The use of intraoperative measurement is effective in reducing LLD after total hip arthroplasty.

Does intraoperative fluoroscopy improve acetabular component positioning and limb-length discrepancy during direct anterior total hip arthroplasty? A meta-analysis

BACKGROUND

The positioning of implant components for total hip arthroplasty (THA) is essential for joint stability, polyethylene liner wear, and range of motion. One potential benefit of the direct anterior approach (DAA) for THA is the ability to use intraoperative fluoroscopy for acetabular cup positioning and limb-length evaluation. Previous studies comparing intraoperative fluoroscopy with no fluoroscopy during DAA have reported conflicting results. This meta-analysis aimed to evaluate whether intraoperative fluoroscopy improves component positioning compared to no fluoroscopy during direct anterior total hip arthroplasty.

METHODS

A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted. We searched Web of Science, EMBASE, PubMed, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CBM, CNKI, VIP, and Wanfang database in May 2023 to identify studies involving intraoperative fluoroscopy versus no fluoroscopy during direct anterior total hip arthroplasty. Finally, we identified 1262 hips assessed in seven studies.

RESULTS

There were no significant differences in terms of acetabular cup inclination angle (ACIA, P = 0.21), ACIA within safe zone rate (P = 0.97), acetabular cup anteversion angle (ACAA, P = 0.26); ACAA within safe zone rate (P = 0.07), combined safe zone rate (P = 0.33), and limb-length discrepancy (LLD, P = 0.21) between two groups.

CONCLUSION

Even though intraoperative fluoroscopy was not related to an improvement in cup location or LDD. With fewer experienced surgeons, the benefit of intraoperative fluoroscopy might become more evident. More adequately powered and well-designed long-term follow-up studies were required to determine whether the application of the intraoperative fluoroscopy for direct anterior total hip arthroplasty will have clinical benefits and improve the survival of prostheses.

Accuracy of Leg Length and Hip Offset Measurements Using a Fluoroscopic Grid During Anterior Approach Total Hip Arthroplasty

Background

Minimizing leg length (LLD) and hip offset (OD) discrepancies is critical for tissue tension and implant longevity in total hip arthroplasty (THA). The direct anterior approach (DAA) helps surgeons recreate these values under fluoroscopy. Several methods to accomplish this have been described, with no consensus on which is superior. This study evaluated the ability to minimize LLD and OD using a surgeon-controlled, adjustable fluoroscopic grid. We hypothesized that this tool would recreate parameters to within 10 mm of the contralateral side.

Methods

One hundred eleven primary THAs performed with an adjustable radiopaque grid to equalize leg length and hip offset were retrospectively reviewed. These values were measured on postoperative radiographs and compared to the contralateral hip. Patients were excluded if they had inadequate imaging, revision arthroplasty, preexisting deformities, or underwent approaches other than DAA.

Results

Mean age was 59.1 ± 11.1 years, 63.1% of patients were female, and average body mass index was 27.8 ± 7.0. Mean LLD was 3.7 ± 3.0 mm, while mean OD was 4.6 ± 3.6 mm. 95.5% of hips showed LLD < 10 mm, while 93.7% of hips had OD < 10 mm. Furthermore, 76.6% of hips had LLD < 5 mm, while 62.2% of hips had OD < 5 mm.

Conclusions

The described technique restored limb length and hip offset during DAA THA. This technique yields consistent results and offers an inexpensive alternative to costly digital software and more cumbersome fixed grid systems.

Intraoperative imaging in hip arthroplasty: a meta-analysis and systematic review of randomized controlled trials and observational studies

BACKGROUND

Intraoperative fluoroscopy (IFC) is gaining popularity in total hip arthroplasty (THA), with the aim to achieve better component positioning and therefore eventually reduced revision rates. This meta-analysis investigated the benefit of IFC by comparing it to intraoperative assessment alone. The primary outcome was component positioning and the secondary outcomes included complications and revision rates.

METHODS

PubMed, Embase and Cochrane Central Register of Controlled Trials were searched for both randomized clinical trials (RCT) and observational studies. Effect estimates for radiographic cup position, offset/leg length difference and outliers from a safe zone were pooled across studies using random effects models and presented as a weighted odds ratio (OR) with a corresponding 95% confidence interval (95% CI).

RESULTS

A total of 10 observational studies involving 1,394 patients were included. No randomized trials were found. IFC showed no significant reduction in acetabular cup position (inclination and anteversion), offset, leg-length discrepancies, revision (none reported) or overall complication rates.

CONCLUSION

The current meta-analysis found no differences in cup positioning, offset, leg length discrepancy, the incidence of complications or revision surgery. It should be acknowledged that the included studies were generally performed by experienced surgeons. The benefit of intraoperative fluoroscopy might become more evident at an early phase of the learning curve for this procedure. Therefore, its role has yet to be defined.

Digital templating cementless short stem total hip arthroplasty: is there a difference in planning adherence between the direct anterior approach and minimally invasive anterolateral approach?

PURPOSE

Minimally invasive approaches (MIS) in total hip arthroplasty (THA) show inconsistent findings regarding planning adherence in digital templating. The purpose of this study is to evaluate any difference in planning adherence between the direct anterior approach (DAA) and an anterolateral MIS approach (AL MIS) in cementless short stem THA.

METHODS

A single surgeon series of 222 THAs in 208 patients with an uncemented short curved stem and a bi-hemispherical acetabular cup were screened for inclusion. A total of 118 THAs were implanted via the DAA and 72 THAs via the AL MIS were included. The planning adherence for the offset option, stem size and the acetabular cup were retrospectively evaluated.

RESULTS

Planning adherence for cup size (perfect match: p = 0.763; ± 1 size: p = 0.124), offset option (0.125) and stem size (perfect match: p = 0.275; ± 1 size: p = 0.552) did not show any statistical significance. Preoperative diagnosis of avascular necrosis of the femoral head in AL MIS approach (OR 6.045; CI 1.153-31.696) or mild hip dysplasia in the general cohort poses (OR 11.789; CI 1.386-100.293) a significant risk for inadequate prediction of the offset option.

CONCLUSION

digital templating for THA with an uncemented short curved stem and a bi-hemispherical acetabular cup show comparable results between a direct anterior approach and a minimally invasive anterolateral approach in supine position. Surgeons should be aware of a low planning adherence for this type of short stem in minimally invasive approaches.

CONCLUSION

Digital templating for THA with an uncemented short curved stem and a bi-hemispherical acetabular cup show comparable results between a direct anterior approach and a minimally invasive anterolateral approach in supine position. Surgeons should be aware of a low planning adherence for this type of short stem in minimally invasive approaches.

Does Intra-operative Fluoroscopy Significantly Improve Component Position in a Primary Total Hip Arthroplasty? Our Experience in a Tertiary Care Hospital

Background

Optimal component placement, equalization of leg lengths, and recreation of offset are important surgical objectives during total hip arthroplasty (THA). Historically, many surgeons have aimed for the Lewinnek's " safe zone," which is defined as 30°-50° of abduction and 5°-25° of anteversion. Methods for optimizing cup position include anatomic landmarks, room landmarks, acetabular cup coverage, and ischial or pubis palpation. Malposition of the acetabular component after total hip arthroplasty (THA) is related to dislocation of the prosthetic femoral head, increased polyethylene liner wear, and limited range of motion. The orientation of the acetabular component comprises inclination and anteversion. Although the inclination of the acetabular component can be easily measured on plain radiographs, the calculation of the anteversion is difficult. This study evaluates the effect of intra-operative fluoroscopy on component position, mainly anteversion and inclination of the acetabular cup, during a total hip arthroplasty.

Methods

106 hips undergoing total hip arthroplasty were assessed, and the decision to use fluoroscopy assistance was randomized based on a simple randomization technique. A total of 48 patients were operated on with fluoroscopy assistance and 58 patients without fluoroscopy assistance. All patients were evaluated postoperatively for version of component on anteroposterior radiographs of the hip using the method of Liaw et al. and for inclination of component on anteroposterior radiographs using the method of Woo and Morrey.

Results

The mean version for the non-fluoroscopy (NF) group was 15.62° and the mean inclination was 44.22°, with 15.5% (9 out of 58) of the patients who did not fit into Lewinnek's safe zone for version and 25.9% (15 out of 58) of the patients who were outliers for inclination of the acetabular cup position. The mean version for the fluoroscopy group (F) was 11.80° and the mean inclination was 47.05°, with 0% (0 out of 48) of the patients who did not fit into Lewinnek's safe zone for version and 12.5% (6 out of 48) of the patients who were outliers for inclination of the acetabular cup position.

Conclusion

While the mean version and inclination of the acetabular component were comparable for both groups, outliers for version and inclination were far more common in the group of patients who underwent surgery without intra-operative fluoroscopic assistance. Therefore, intra-operative fluoroscopy imaging confirms appropriate inclination (abduction) and version of acetabular cup position according to Lewinnek's safe zone and prevents undesirable component position during a total hip arthroplasty while adding a maximum of 5 min to the operative time.

Assessing Leg Length and Offset in Anterior Total Hip Arthroplasty: Overlay Versus AP Pelvis Intraoperative Radiographic Techniques: A Retrospective Cohort Study

INTRODUCTION

Two intraoperative radiographic techniques to determine leg length and offset during anterior total hip arthroplasty (THA) are the AP pelvis and overlay techniques. The AP pelvis method measures LLDs and offset using AP fluoroscopic images, whereas the overlay method uses printed images of the native and replaced hips. The purpose of this study was to compare these techniques regarding clinical and radiographic LLD and offset discrepancies.

METHODS

Patients of a single surgeon at two hospitals from September 2017 to January 2021 were retrospectively reviewed. Clinically detectable LLD was recorded. Radiographic measurements were obtained from preoperative and postoperative radiographs. LLD was determined based on the vertical distance between the lesser trochanters and the ischial tuberosities. Total offset was measured using a combination of femoral and medial offset. The Student t-test, Fisher exact test, and Wilcoxon rank sum tests were used for statistical analysis.

RESULTS

Seventy-one procedures were done using the overlay technique and 61 used for the AP pelvis technique. No significant differences were observed in mean postoperative LLD (2.66 versus 2.88 mm, P = 0.66) and mean postoperative offset discrepancy (5.37 versus 4.21 mm, P = 0.143) between the overlay versus AP pelvis groups. The mean preoperative to postoperative absolute difference in offset was less than 5 mm in both groups. Clinically detectable LLD was noted in six of 71 patients in the overlay group and one of 61 in the AP pelvis group (P = 0.123).

CONCLUSION

No notable differences were observed in intraoperative leg length and offset discrepancies during direct anterior THA between the AP pelvis and overlay techniques, suggesting they are equally effective in determining LLD and offset intraoperatively. The choice of technique to use anterior THA should be based primarily on the surgeon's preference, comfort, and available resources.

Intraoperative method of femoral head central measurement to prevent leg length discrepancy following hemiarthroplasty

Purpose

This study aimed to introduce and investigate the safety and efficiency of the intraoperative central measurement method of the femoral head (IM-CMFH) to prevent leg length discrepancies (LLD) after hemiarthroplasty.

Methods

Overall, 79 patients aged 75 to 85 years with femoral neck fractures who underwent hemiarthroplasty were divided into two groups: the Control group (n = 46) and the IM-CMFH group (n = 33). The two groups were compared for postoperative LLD and the proportions of patients with greater than 10 mm, 6-10 mm, and within 5 mm, postoperative femoral offset (FO) difference and the proportions of patients within 5 mm, incremental greater than 5 mm and reduction greater than 5 mm. Next, the vertical distance from the center of the femoral head to the tip of the greater trochanter on the anatomical axis of the femur (VD-CFH-TGTAAF), leg length, and FO on the operative and non-operative sides within the IM-CMFH group. Finally, operative time, hemoglobin loss, Harris scores 3 months after surgery, and postoperative complications were analyzed.

Results

Compared with the control group, the postoperative LLD and FO differences were significantly lower in the IM-CMFH group (P = 0.031; P = 0.012), and the proportion of patients with postoperative LLD greater than 10 mm decreased significantly (P = 0.041), while the proportion of patients with FO difference of within 5 mm increased (P = 0.009). In addition, there was no significant difference in the operative time, hemoglobin loss, and Harris score at 3 months postoperatively and postoperative complications between the two groups (P > 0.05). There was no significant difference in FO, leg-length, and VD-CFH-TGTAAF between the operative and non-operative sides within the IM-CMFH group (P > 0.05).

Conclusion

Satisfactory results can be achieved by using the IM-CMFH to prevent LLD following hemiarthroplasty, and there is no increase in operative time, hemoglobin loss, or postoperative complications. This technique is efficient for hemiarthroplasties and is both simple and convenient.

Impact of intraoperative fluoroscopic beam positioning relative to the hip and pelvis on perceived acetabular component position

Background

Parallax is poorly understood and can mislead surgeons using intraoperative fluoroscopy (IF) to guide cup placement during anterior approach (AA) total hip arthroplasty. The purpose of this study was to examine how changes in fluoroscopic beam positioning in relation to the hip and pelvis affects the projected acetabular image.

Methods

An acetabular component was positioned in an anatomic pelvis model in 45° and 20° of abduction and anteversion, respectively using a computer assisted cup targeting system. Fluoroscopic images were taken at various caudal and cranially directed angles with the fluoroscopic beam centered over the hip then pelvis. In each position, four independent observers measured the abduction and anteversion angles of the projected cup image using the same computer targeting system.

Results

Cup abduction and anteversion measured 43.5° and 19.5° when IF was centered over the hip and 40.5 and 27.5° when centered over the pelvis in the neutral position. Increasing the caudal direction of the beam 20° increased the projected abduction/anteversion angles by approximately 7°/12° and 9°/16° when centered over the hip and pelvis respectively. Increasing the cranial direction of the beam 20° decreased the measured abduction/anteversion angles by roughly 4°/20° and 4°/24° when centered over the hip and pelvis, respectively.

Conclusion

The projected image of the acetabular component can change dramatically depending on fluoroscopic beam position relative to the hip and pelvis. Recognizing the approximate direction and magnitude of change with differing fluoroscopy positions may help surgeons avoid cup malpositioning.

The effectiveness and influencing factors of the "Y" line technique in reducing the leg length discrepancy after total hip arthroplasty

Objective

To introduce a surgical technique (the "Y" line technique) that will control leg length discrepancy (LLD) after total hip arthroplasty and to observe its effectiveness and influencing factors.

Methods

According to the inclusion and exclusion criteria, a total of 350 patients were selected in this study; 134 patients in whom used the "Y" line technique was used to control lower limb length were included in Group A and 166 patients treated with freehand methods to control lower limb length were included in Group B. A total of 50 patients in whom the standard anteroposterior x-ray of bilateral hips was taken preoperatively and in whom the "Y" line technique was used during the operation were included in Group C.

Results

The postoperative LLD of Group A was 4.74 mm (3.93), that of Group B was 5.85 mm (4.60), and that of Group C was 2 mm (1.00)-the difference was statistically significant (p < 0.001). There were significant statistical differences when comparisons were made between any two groups (p < 0.01). The distribution of postoperative LLD in Group A was better than that in Group B, and this factor was better in Group C than in Group A-the difference was statistically significant (p < 0.001). Severe unequal length rates of the lower extremities (LLD > 10 mm) were 5.97% (8/134) in Group A, 14.3% (24/166) in Group B, and 0% (0/50) in Group C-the difference was statistically significant (p < 0.001). There were significant differences between Group A and Group B and between Group B and Group C (p < 0.05), but there was no significant difference between Group A and Group C (p = 0.078).

Conclusion

The "Y" line technique, which does not increase the operating time and patient cost, can effectively reduce postoperative LLD. Insufficient internal rotation of the healthy lower extremity and the low projection position in the preoperative anteroposterior x-ray of the bilateral hips were important factors affecting the accuracy of the "Y" line technique.

Utilizing Three-Dimensional Head-Lesser Trochanter Distance Could Further Reduce Leg Length Inequality in Primary Bipolar Hemiarthroplasty

Background: The aim of this study was to investigate whether the use of three-dimensional (3-D) computed tomography (CT)-based head-lesser trochanter distance (HLD) could reduce leg length discrepancy (LLD) more than the use of a two-dimensional (2-D) plain film method in primary bipolar hemiarthroplasty. Methods: Propensity score matching (PSM) analysis was used to adjust the confounding factors. A retrospective comparative analysis of 128 patients was performed. In the control group, the leg length was equalized using the 2-D, plain film-based HLD. In the study group, primary bipolar hemiarthroplasty was performed using the 3-D CT-based HLD method. Postoperative LLDs were compared between the two groups using the method of Ranawat. In addition, the Harris hip score (HHS) was evaluated and compared at one year after surgery. Results: A significant difference was observed in mean postoperative LLD between the 2-D HLD group and the 3-D CT HLD group: 1.6 ± 1.2 mm (range, 0.1−6.0 mm) and 1.1 ± 1.2 mm (range, 0.1−5.1 mm), respectively (p < 0.05). Additionally, a higher percentage of patients in the 3-D CT HLD group had an LLD of less than 2 mm. The mean HHS at one year after surgery showed no significant difference between the two groups. Conclusions: To minimize the occurrence of LLD, HLD measurement from a CT scanner may be more accurate than an X-ray. The 2-D and 3-D HLD differences in the 3-D CT HLD group were statistically significant. Using a 3-D, CT-based HLD method might decrease the possibility of an LLD over 2 mm.

Digital Fluoroscopic Navigation for Limb Length Restoration During Anterior Total Hip Arthroplasty

Background

Restoration of limb length is important in total hip arthroplasty. Clinical evaluation and preoperative templating establish the intended lengthening. The purpose of this study was to assess whether digital fluoroscopic navigation (DF) improved the accuracy of planned lengthening in direct anterior approach total hip arthroplasty (DAA-THA).

Methods

Planned lengthening measurements on 100 consecutive unilateral DAA-THA patients, along with patient characteristics, were prospectively collected by 2 surgeons. One surgeon utilized DF to achieve intended length (n = 50), while the other utilized unaided standard fluoroscopy (SF; n = 50). A third surgeon blinded to the procedures assessed actual limb length using an ipsilateral overlay technique on the 6-week postoperative radiograph. The difference between the mean planned and actual limb lengthening stratified by DF and SF was assessed using bivariate and multivariate statistics.

Results

The mean (standard deviation) planned lengthening in DF and SF groups was 3.96 (2.1) and 3.47 (2.2) mm, respectively. The mean (standard deviation) actual lengthening in DF and SF groups was 3.11 (4.0) and 0.68 (4.6) mm, respectively. After accounting for age, sex, body mass index, laterality, and the Bone Index, multivariate regression results showed that the average difference between planned and actual limb lengthening in the DF group was significantly lower than that in the SF group (β = -1.92; 95% confidence interval: -3.51, -0.33; P < .02). A greater percentage of patients in the DF group (66% vs 40%) were within 3 mm of the intended plan (P < .01).

Conclusions

Fluoroscopy helps achieve the intended surgical lengthening in DAA-THA. The use of DF resulted in more accurate execution of lengthening.

High varus stem alignment in short-stem total hip arthroplasty: a risk for reconstruction of femoro-acetabular offset, leg length discrepancy and stem undersizing?

PURPOSE

Short stems are increasingly used in in total hip arthroplasty (THA) because of advantages in bone and soft tissue preservation and reconstruction of hip geometry. Short stems can be inserted in a more varus position compared to conventional straight stems. This poses the risk of final varus misplacement of the femoral component, which is not intended in all femoral short stems.

METHODS

We wanted to evaluate the effect of a high varus stem positioning in MIS THA on hip offset, leg length and femoral canal fill index. A series of 1052 consecutive THAs with a singular cementless femoral short stem and press-fit cup was retrospectively screened for inclusion. One hundred six patients with unilateral THA and a contralateral healthy hip met the inclusion criteria. Measurements were carried out on preoperative and 3 months anterior-posterior postoperative radiographs. Patients were divided into Group A (varus stem alignment ≤ 3°) and Group B (varus stem alignment > 3°).

RESULTS

Hip offset (HO) increased significantly in Group B by 4 mm (p = 0.013). No influence on leg length difference was detected in both groups. Preoperative CCD angle was significantly lower in Group B (p < 0.001). Canal Fill Indices (CFI) were significantly lower in Group B (CFI I: p < 0.001; CFI II p = 0.003; CF III p = 0.002).

CONCLUSION

High varus stem alignment > 3° leads to a statistically significant but minor increase in HO and poses the risk of stem undersizing. A preoperatively low genuine CCD angle pose a risk for varus stem positioning.

Improved hip symmetry with an adjustable fluoroscopic grid during total hip arthroplasty

BACKGROUND

The use of intraoperative fluoroscopy (IF) is common with direct anterior total hip arthroplasty (THA), however image distortion in IF may limit its usefulness. The supplementation of IF with an adjustable grid (AG) may provide consistently better accuracy in component placement. Therefore, the purpose of this study was to compare the accuracy, consistency, and surgical efficiency between IF only and AG supplementation.

METHODS

2 cohorts were retrospectively evaluated, including 573 IF only patients and 211 AG patients having undergone unilateral THA between 2011 and 2018. Post-THA radiographic assessment was performed to evaluate the accuracy of component placement, with target placements for global hip offset (GHO) and leg-length differences (LLD) <10 mm and acetabular cup abduction of 45° (±10°). Accuracy and surgical efficiency were evaluated between groups and over time.

RESULTS

The AG group had a significant greater percentage of components placed within the target zone compared to IF only for GHO (99.5%, 92.7%, p < 0.001), LLD (99.1%, 96.5%, p = 0.039) and abduction (99.5%, 96.3%, p = 0.009), with no difference in fluoroscopic time (p = 0.973). Over time, accuracy was significantly different in IF group for GHO (p = 0.008) and abduction (p = 0.002) and trended toward significance for LLD (p = 0.055). There were no significant differences over time for the AG group.

CONCLUSIONS

The addition of an AG to IF significantly increased the accuracy of component placement during direct anterior THA. These results were consistent over 2 years of use and did not decrease surgical efficiency.

Intraoperative Imaging in Total Hip Arthroplasty Is Cost-Effective Regardless of Surgical Approach

BACKGROUND

Component positioning in total hip arthroplasty (THA) may be improved with utilization of intraoperative imaging. The purpose of this study is to determine if intraoperative imaging during THA is cost-effective.

METHODS

A break-even analysis was used as a model for cost-effectiveness, which incorporates cost of imaging (including direct charges and the additional time required for imaging), rate of revision surgery, and cost of revision surgery, yielding a final revision rate that needs to be achieved with use of intraoperative imaging in order for its use to be cost-effective. Absolute risk reduction (ARR) is determined by the difference between the initial revision rate and final revision rate.

RESULTS

At an anticipated institutional cost of $120 and requiring 4 additional minutes, intraoperative fluoroscopy would be cost-effective if the baseline rate of revision due to component mispositioning (0.62%) is reduced to 0.46%. Intraoperative flat plate radiographs ($127) are cost-effective at an ARR of 0.16%. Cost-effectiveness is achieved with lower ARR in the setting of lower imaging costs ($15, ARR 0.02%), and higher ARR with higher imaging costs ($225, ARR 0.29%). ARR for cost-effectiveness is independent of baseline revision rate, but varies with the cost of revision procedures.

CONCLUSION

At current revision rates for component malpositioning, only 1 revision among 400 THAs needs to be prevented for the utilization of fluoroscopy (or 1 in 385 THAs with flat plate imaging), to achieve cost-effectiveness.

Component placement accuracy of two digital intraoperative fluoroscopy supplementation systems in direct anterior total hip arthroplasty

INTRODUCTION

Intraoperative fluoroscopy (IF) may increase accuracy of component placement when performing direct anterior approach total hip arthroplasty (THA), however, unguided IF continues to produce inconsistent results. Supplementation of IF, with a digital grid (Grid) system or digital overlay (Overlay), may increase component placement accuracy. The purpose of this study was to compare component placement accuracy following THA when IF was supplemented with the Grid or Overlay technique.

MATERIALS AND METHODS

Acetabular abduction and anteversion, with leg length discrepancy (LLD) and global hip offset (GHO) were retrospectively evaluated for unilateral and bilateral THA patients from 6-week post-operative radiographs. Target component placement were GHO and LLD < 10 mm, abduction 45° ± 10° and anteversion 15° ± 10° for Overlay and 17° ± 10° for Grid. Differences between the Overlay and Grid were determined by univariate analyses.

RESULTS

The Overlay and Grid groups included 178 patients (217 hips) and 262 patients (317 hips), respectively. Target placement with the Overlay and Grid was achieved for GHO in 98.3% and 95.7% of cases (p = 0.108), LLD in 100% and 98.4% of cases (p = 0.121), cup abduction in 98.2% and 97.4% of cases (p = 0.384), and cup anteversion in 97.7% and 71.1% of cases (p < 0.001), respectively. Surgical time was significantly longer in Overlay compared to Grid (Unilateral 77.5 ± 14.1 min and 68.8 ± 12.2; p < 0.001; Bilateral 184.6 ± 27.0 min and 165.5 ± 23.1; p < 0.001, respectively).

CONCLUSION

Although no difference was found between the Grid and the Overlay cohorts for LLD, GHO or abduction angle, the Overlay resulted in greater accuracy for acetabular component anteversion angle, with only a slight decrease in surgical efficiency.

A single-surgeon experience in reconstruction of femoro-acetabular offset and implant positioning in direct anterior approach and anterolateral MIS approach with a curved short stem

PURPOSE

Minimally invasive surgery using short stems in total hip arthroplasty gained more popularity. The differences in change of hip offset and implant positioning in minimally invasive approaches are not fully known. Therefore, this study was conducted to evaluate the difference in reconstruction of hip offset and implant positioning in direct anterior approach (DAA) and minimally invasive anterolateral approach (AL MIS).

METHODS

A single surgeon series of 117 hips (117 patients; mean age 65.54 years ± 11.47; index surgery 2014-2018) were included and allocated into two groups: group A (DAA) with 70 hips and Group B (AL MIS) with 47 patients operated. In both groups the same type of cementless curved short hip stem and press fit cup was used.

RESULTS

Both groups showed an equal statistically significant increase of femoral (p < 0.001) and decrease of acetabular offset (p < 0.001). Between both groups no statistically significant difference in offset reconstruction, leg length difference or implant positioning could be found. Leg length increased in both groups significantly and leg length discrepancy showed no difference (group A: - 0.06 mm; group B: 1.11 mm; p < 0.001). A comparable number of cups were positioned outside the target zone regarding cup anteversion.

CONCLUSION

The usage of a curved short stem shows an equal reconstruction of femoro-acetabular offset, leg length and implant positioning in both MIS approaches. The results of this study show comparable results to the existing literature regarding change of offset and restoration of leg length. Malposition of the acetabular component regarding anteversion poses a risk.

THA with Use of Patient-Specific Resurfacing Jigs and a Novel Customized Implant Design

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Conventional total hip arthroplasty (THA) largely remains an unguided procedure dependent on the ability and experience of the surgeon. New technologies, such as patient-specific instrumentation and robotics, have shown promising results in improving implant positioning, which has the potential to improve patient outcomes.

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The use of off-the-shelf (OTS) implant designs, however, limits the success of the technological advances since they are unable to recreate the native anatomy of the joint. The inability to restore femoral offset and version or the presence of implant-related leg-length discrepancies often lead to suboptimal surgical results that increase the risk of dislocation, fractures, and component wear, compromising postoperative functional outcomes and implant longevity.

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A customized THA system, whereby the femoral stem is designed to restore patient anatomy, has recently been introduced. The THA system uses computed tomography (CT)-derived 3D imaging to create a custom stem, patient-specific component placement, and patient-specific instrumentation that matches the patient's native anatomy.

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The purpose of this article is to provide information on the design and manufacturing process of this new THA implant, to illustrate the associated preoperative planning, and to describe the surgical technique; 3 surgical cases are presented.

Consistency of Acetabular Height in Sequential Bilateral Total Hip Arthroplasty

Background

Achieving appropriate leg length after surgery remains a concern for surgeons performing total hip arthroplasty (THA). The focus of surgeons trying to equalize leg length has been primarily on positioning of the femoral implant. This study evaluates the impact of acetabular height on leg length and its impact on femoral component choices during THA.

Methods

We reviewed standing pelvic radiographs of 100 patients who underwent staged bilateral THA by a single surgeon from 2016 to 2019. Leg length discrepancies and acetabular heights were determined from preoperative and postoperative radiographs. The difference between the first and second operative hips was compared at each stage of the procedures. Results were analyzed using paired t-tests.

Results

There is a significant increase in mean leg length and acetabular height after both the first and second stages of the procedure. Although there was a small change in average acetabular height for each procedure, height increased or decreased by greater than 5 mm in 44 of 200 cases. Comparing left to right hips after the second surgery disclosed no statistically significant differences in acetabular height or leg length.

Conclusion

Acetabular height and leg length changes with each stage of the procedure in sequential bilateral THA. In almost 25% of cases, the acetabular height changed by more than 5 mm. This has significant implications and needs to be considered during preoperative planning as well as operative decision-making. To account for these differences, a THA may require intraoperative acetabular assessment and changes in femoral positioning and sizing to achieve the optimal leg length.

Reliability of a simple fluoroscopic image to assess leg length discrepancy during direct anterior approach total hip arthroplasty

BACKGROUND

Direct anterior approach (DAA) total hip arthroplasty (THA) in a supine position provides a unique opportunity to assess leg length discrepancy (LLD) intra-operatively with fluoroscopy. Reported fluoroscopic techniques are useful but are generally complicated or costly. Despite the use of multiple techniques for leg length assessment, LLD continues to be a major post-operative source of patient dissatisfaction further emphasizing the importance of near-anatomic restoration. The utility of an alternative direct measurement of LLD on an intra-operative fluoroscopic pelvic image during DAA THA has not been reported.

AIM

To determine the reliability of a novel simple intra-operative measurement of LLD using a parallel line technique on a single fluoroscopic digital image of the pelvis.

METHODS

One hundred and seventy-one patients who underwent DAA THA were included for analysis. Intra-operative fluoroscopic and post-operative anterior-posterior radiographs were imported to TraumaCad and calibrated for LLD measurement. LLD was measured on each image using the right-left hip differences in lesser trochanter to pelvic reference line distances. Pelvic reference points included the teardrops and ischia. Fluoroscopic LLD was compared to the gold-standard measurement of LLD measured on a post-operative radiograph.

RESULTS

Mean absolute difference in teardrop referenced LLD between fluoroscopic and post-operative radiographs was 2.17 mm and based on the ischia mean absolute difference was 2.63 mm. Linear regression of fluoroscopic and post-operative radiograph LLD based on teardrop and ischia LLD found r² values of 0.57 and 0.84, respectively. Mean absolute difference between fluoroscopic and post-operative x-ray LLD was within 5 mm in 95% of cases regardless of pelvic reference.

CONCLUSION

This study demonstrates that a single fluoroscopic view obtained during DAA THA for leg length assessment is clinically useful.

The Effect of Intraoperative Radiographs on Component Position and Leg Length during Routine Posterior Approach Total Hip Arthroplasty

Purpose

Accurate component placement and restoration of patient anatomy are critical in total hip arthroplasty (THA) surgery. Although intraoperative radiographs are sometimes utilized, it is unclear whether this practice can improve accuracy.

Materials and Methods

This study evaluated acetabular cup abduction, anteversion, leg length, and offset among 100 posterior approach THAs performed without imaging (No X-ray group) and compared them to a subsequent series of 100 THAs where an intraoperative radiograph was taken with the trial components in place (X-ray group). THAs were performed using a posterior approach by a single, experienced surgeon whose goal was to place the cup at 45° of abduction and 30° of anteversion. Supine anteroposterior pelvic digital radiographs taken at the first (nominal 4-week) postoperative visit were used for measurements.

Results

Slight differences in cup abduction (47°±6° vs 44°±6°, respectively, P=0.003) and anteversion angle (35°±6° vs 31°±6°, respectively, P<0.001) were observed between the X-ray and No X-ray groups; however, a similar proportion of cups within 10° of the target angles was observed (76% vs 83%, respectively, P=0.22). No difference in offset measurements (1.1±6.6 mm vs 0.3±6.9 mm, respectively, P=0.42) or leg lengths (0.3±3.8 mm vs 0.3±4.8 mm, respectively, P=0.94) was observed between the X-ray and No X-ray groups; however, the X-ray group showed less leg length variation (P=0.05).

Conclusion

In this study, the routine use of intraoperative radiographs was not associated with improved implant positioning for uncomplicated primary THA.

Comparing Postoperative Leg Length Discrepancy and Femoral Offset Using Two Different Surgical Approaches for Hemiarthroplasty of the Hip

INTRODUCTION

The direct anterior approach (DAA) and anterolateral approach (ALA) may be used for hip hemiarthroplasty (HHA) as a treatment for femoral neck fractures. The DAA often utilizes intraoperative fluoroscopy to determine leg length and offset, while the ALA traditionally utilizes an intraoperative clinical exam to determine offset and leg length. This study will evaluate two techniques: the "grid fluoroscopy [GF] technique" and the "intraoperative exam [IE] technique," each performed by one of two separate surgeons, and compare each technique's accuracy to restore leg length and femoral offset in a patient population that underwent HHA.

METHODS

Two investigators retrospectively reviewed charts of 208 randomly selected patients who had an HHA from either a DAA or ALA performed by two different surgeons for the treatment of femoral neck fractures. Postoperative AP pelvis radiographs were measured to determine offset and leg length compared with the non-operative extremity. Non-normal continuous variables were provided by median and interquartile range. Data were analyzed with the Mann-Whitney U test and Student's t-test.

RESULTS

After inclusion and exclusion criteria, data were reviewed on 173 hemiarthroplasties. The mean age was 80.3 years (± 11.2 years). Of the surgical patients, 65.9% were female, and 70.9% identified their ethnicity as white. The DAA was used in 93 patients and ALA in 80 patients. Analysis comparing the two techniques demonstrated no statistically significant differences in median leg length between GF technique (1.02 IQR -0.1, 2.0 mm) and IE technique (1.25 IQR -2.4, 1.3 mm,) (p=0.67). There was also no statistically significant difference in offset between GF technique (1.3 IQR 0.2, 2.1 mm) and IE technique (0.6 IQR -2.7 mm, 3.2 mm) (p=0.13). However, a difference was found in mean length of surgery that was statistically significant. We found that the mean length of surgery for the IE technique was 74.8 ± 24.7 minutes versus the GF technique, which was 95.1 ± 23.0 minutes, (p<0.0001).

DISCUSSION

There was no significant difference between leg length and offset with the use of intraoperative fluoroscopy with DAA compared to no intraoperative imaging with ALA. Our study suggests that DAA and ALA are equally effective approaches for re-establishing symmetric leg length and offset in HHA for femoral neck fractures. In this study, the ALA had a shorter surgical time compared to DAA, potentially due to the utilization of intraoperative fluoroscopy for this particular technique during the DAA.

Are We Being Fooled by Fluoroscopy? Distortion May Affect Limb-Length Measurements in Direct Anterior Total Hip Arthroplasty

BACKGROUND

Distortion is an intrinsic phenomenon associated with image-intensified fluoroscopy that is both poorly understood and infrequently appreciated by orthopedic surgeons. Little information exists regarding its potential influence on intraoperative parameters during orthopedic surgery, let alone during direct anterior (DA) total hip arthroplasty (THA). The purpose of this study was to quantify the amount of potential error caused by fluoroscopic distortion during DA THA.

METHODS

Intra-operative fluoroscopic pelvic images from 74 DA THAs were reviewed by two independent readers. All images were obtained using the same fluoroscopic C-arm unit with a radiopaque grid attached to the image intensifier. The vertical distortion from a straight central horizontal line at the peripheries of images were measured and summed to yield the combined vertical distortion similar to how a surgeon calculates a side to side comparison of limb lengths. Simple linear regression was used to evaluate associations between total distortion and patient demographics, operating theaters, and various operative parameters.

RESULTS

The average combined distortion was 10.0mm (range 2.0-20.0mm). There was a significant difference in the average distortion observed in different theaters (P < .001). There was no association between distortion and patient demographics or fluoroscopic time (all, P > .05).

CONCLUSION

Fluoroscopic distortion is unpredictable and can cause a substantial amount of error when comparing limb lengths during DA THA. This is a critical finding as this amount of inaccuracy could lead to unintended implant positioning and limb-length discrepancies if unaccounted for.

Acetabular and Femoral Component Positioning Using Direct Anterior Approach Versus Posterior Approach in Total Hip Arthroplasty

PURPOSE

Direct anterior approach (DAA) has recently become popular in total hip arthroplasty (THA). However, irrespective of the surgical approach used, component malposition is an important factor affecting function and complications after THA. This study aims to compare component positioning on the femoral and acetabular side between DAA and posterior approach (PA) to the hip joint. We hypothesized that the two approaches are similar in terms of component positioning.

METHODS

We prospectively studied 50 patients, matched according to age, sex, and body mass index, undergoing THA, divided non-randomly into 2 groups. Group 1 comprised 25 patients (35 hips) undergoing THA using DAA and group 2 comprised 25 patients (25 hips) undergoing THA using PA. Ten patients from group 1 had simultaneous bilateral THA. Radiological parameters studied were acetabular inclination (AI), coronal femoral stem alignment (CFA), leg length difference (LLD), acetabular cup version (AV), and femoral stem version (FV).

RESULTS

There was no significant difference in AI, CFA, LLD, AV, and FV between the two groups. Excellent to good inter and intra-observer reliability expressed in terms of intraclass correlation coefficient (ICC) was noted for all the radiographic measurements.

CONCLUSION

Both DAA and PA for THA achieve comparable radiological component positioning. DAA may not provide any advantage over PA in terms of positioning of the prosthesis.

LEVEL OF EVIDENCE

Level II, non-randomized comparative study.

Comparison of Component Placement Accuracy Using Two Intraoperative Fluoroscopic Grid Technologies During Direct Anterior Total Hip Arthroplasty

BACKGROUND

Intraoperative fluoroscopy is beneficial when performing total hip arthroplasty (THA) via the direct anterior approach; however, image distortion may influence component placement. A manual gridding system (MGS) and a digital gridding system (DGS) are commercially available, aimed at visually representing or correcting image distortion. Therefore, the purpose of this study is to compare component placement accuracy following direct anterior approach THA when intraoperative fluoroscopy was supplemented with MGS or DGS.

METHODS

A retrospective evaluation of acetabular cup abduction (ABD), leg length discrepancy (LLD) and global hip offset difference (GHO) was completed for consecutive patients from 6 week post-THA weight-bearing radiographs. The predefined target LLD and GHO was <10 mm and ABD target was 45° ± 10°. Differences between MGS and DGS were determined by independent t-tests.

RESULTS

The MGS (250 patients, 315 hips) and DGS (183 patients, 218 hips) achieved targeted ABD in 98.7% and 96.8% of cases, respectively, and ABD was significantly lower in the MGS group (45.14 ± 4.03° and 47.01 ± 4.39°, respectively) (P < .001). Compared to MGS, the DGS group averaged significantly higher GHO (3.64 ± 2.44 and 4.45 ± 2.73 mm, respectively, P = .002) but was not significantly different regarding LLD (2.92 ± 2.55 and 3.19 ± 2.46 mm, respectively, P = .275). No significant group difference was noted for percentage within the targeted LLD and GHO; however, 93.5% of DGS and 97.6% of MGS achieved all three (P = .031).

CONCLUSION

The use of both the MGS and DGS resulted in consistent component placement within the predefined target zone. Although the MGS appeared to be slightly more consistent, these differences are unlikely to be clinically significant.

A comparison of leg length discrepancy between direct anterior and anterolateral approaches in total hip arthroplasty

Background

Leg length discrepancy (LLD) after total hip arthroplasty (THA) is a known source of complications and a leading cause of litigation (J Bone Joint Surg Br 87:155–157, 2005). There are limited studies investigating surgical approach combined with the use of fluoroscopy intraoperatively and their potential effects on LLD after THA. The purpose of this study was to compare the direct anterior (DA) approach utilizing a fluoroscopic overlay technique and anterolateral (AL) approach and their potential effect on LLD.

Methods

We retrospectively reviewed 121 patients who had undergone primary THA from September 1, 2016 to November 1, 2018 by either DA or AL approach by two separate surgeons. Leg length discrepancies were measured on pre-operative post-anesthesia care unit (PACU) and on post-operative low anterior/posterior (AP) pelvis plain radiographs by two investigators blinded to each other’s measurements. To confirm inter-observer and intra-observer reliability between LLD measurements amongst investigators, a Pearson correlation test was performed. The primary outcome measurement was leg length discrepancy (LLD).

Results

We observed LLD > 1.0 cm and LLD > 1.5 cm in the DA and AL groups. The DA approach group showed a mean LLD of 4.5 mm against 7.76 mm in the AL group (p < 0.00001). There was a significantly higher rate of LLD in the AL group as compared to the DA group (LLD> 1 cm (28% vs. 8%, p = 0.0037) and LLD > 1.5 cm (7% vs. 0%, p = 0.0096). The LLD measurements showed strong correlation in terms of inter-observer (r = 0.95) and intra-observer reliability (r = 0.99) between the two investigators (p < 0.001).

Conclusion

In our patient cohort, the DA approach with fluoroscopic overlay technique had less LLD in comparison with the AL approach, suggesting that intraoperative fluoroscopic use does have an impact on LLD.

Total hip arthroplasty performed by direct anterior approach - Does experience influence the learning curve?

INTRODUCTION

Proficiency in the direct anterior approach (DAA) as with many surgical techniques is considered to be challenging. Added to this is the controversy of the benefits of DAA compared to other total hip arthroplasty (THA) approaches. Our study aims to assess the influence of experience on learning curve and clinical results when transitioning from THA via posterior approach in a lateral position to DAA in a supine position.

METHODS

A consecutive retrospective series of 525 total hip arthroplasty of one senior and six junior surgeons was retrospectively analysed from May 2013 to December 2017. Clinical results were analysed and compared between the two groups and represented as a learning curve. Mean follow up was 36.2 months ± 11.8.

RESULTS

This study found a significant difference in complications between the senior and junior surgeons for operating time, infection rate, and lateral femoral cutaneous nerve (LFCN) neuropraxia. A trainee's learning curve was an average of 10 DAA procedures before matching the senior surgeon. Of note, the early complications correlated with intraoperative fractures increased with experience in both groups. Operating time for the senior equalised after 70 cases. Dislocation rate and limb length discrepancy were excellent and did not show a learning curve between the two groups.

CONCLUSION

DAA is a safe approach to implant a THA. There is a learning curve and initial supervision is recommended for both seniors and trainees.

LEVEL OF EVIDENCE

Retrospective, consecutive case series; level IV.

A Comparison of Risk of Dislocation and Cause-Specific Revision Between Direct Anterior and Posterior Approach Following Elective Cementless Total Hip Arthroplasty

BACKGROUND

Use of the direct anterior approach (DAA) for total hip arthroplasty (THA) has increased over the last decade. We sought to investigate whether (1) a difference exists in dislocation risk for DAA compared with posterior THA, (2) a difference exists in risk for specific revision reasons, and (3) the likelihood of adverse 90-day postoperative events differs.

METHODS

We conducted a cohort study using data from Kaiser Permanente's Total Joint Replacement Registry. Patients aged ≥18 years who underwent primary cementless THA for osteoarthritis with a highly cross-linked polyethylene liner were included (2009-2017). Multivariable Cox proportional hazards regression was used to evaluate dislocation and cause-specific revision risks, and multivariable logistic regression was used to evaluate 90-day emergency department visits, 90-day unplanned readmissions, and 90-day complications (including deep infection, deep vein thrombosis, and pulmonary embolism).

RESULTS

Of 38,399 primary THA, 6428 (16.7%) were DAA. All-cause revision at 2-years follow-up was 1.78% (95% confidence interval [CI] = 1.46-2.17) for DAA and 2.28% (95% CI = 2.11-2.45) for posterior. After adjusting for covariates, DAA had a lower risk of dislocation (hazard ratio [HR] = 0.39, 95% CI = 0.29-0.53), revision for instability (HR = 0.33, 95% CI = 0.18-0.58), revision for periprosthetic fracture (HR = 0.57, 95% CI = 0.34-0.96), and readmission (odds ratio = 0.82, 95% CI = 0.67-0.99) compared with posterior approach but a higher risk of revision for aseptic loosening (HR = 2.26, 95% CI = 1.35-3.79).

CONCLUSION

While the DAA associated with lower risks of dislocation and revision for instability and periprosthetic fracture, it is associated with a higher revision risk for aseptic loosening. Surgeons should discuss these risks with their patients.

Does An Augmented Reality-based Portable Navigation System Improve the Accuracy of Acetabular Component Orientation During THA? A Randomized Controlled Trial

BACKGROUND

We developed an augmented reality (AR)-based portable navigation system in which the surgeon can view the pelvic plane and placement angle of an acetabular cup on the display of a smartphone during THA.

QUESTIONS/PURPOSES

(1) Is acetabular component placement more accurate using the AR-based portable navigation system compared with the conventional freehand technique? (2) Is intraoperative measurement of placement angle more accurate when using the AR-based portable navigation system compared with a goniometer?

METHODS

Forty-six patients were randomly assigned to undergo acetabular cup placement during THA using the AR-based portable navigation system (AR navigation group) or placement of a mechanical alignment guide (conventional group). All surgeries were performed with the patient in the lateral decubitus position. We compared the absolute value of the difference between the targeted placement angle and postoperative measured placement angle between the groups using two types of imaging (radiography and CT).

RESULTS

In terms of radiographic inclination, the mean differences between the targeted placement angle and postoperative measured angle were smaller in the AR navigation group than in the conventional group for both radiographs and CT images (2.3° ± 1.4° versus 3.9° ± 2.4°, respectively; p = 0.009 and 1.9° ± 1.3° versus 3.4° ± 2.6°, respectively; p = 0.02). There were no differences in radiographic anteversion between the two groups. No complications were associated with the use of the AR-based portable navigation system.

CONCLUSIONS

This system yielded no differences in acetabular anteversion accuracy, and no clinically important differences in acetabular inclination. Therefore, at this time we cannot recommend this device as its costs and risks cannot be justified based on the absence of a clinically meaningful difference in cup placement accuracy. Although we detected no complications, this was a small series, and this approach adds both surgical time and pins in the ilium.

LEVEL OF EVIDENCE

Level I, therapeutic study.

A new method for intraoperative assessment of leg length, sizing and placement of the components in total hip replacement

BACKGROUND

Intraoperative radiograph of the pelvis is a well-established way to avoid misplacement/undersizing of the components and leg length discrepancy (LLD) in total hip replacement (THR). We describe a method for the obtainment and the evaluation of intraoperative radiographs with a sophisticated wireless radiographic system and a computerized digital tool originally used for preoperative templating.

METHODS

In this retrospective case-control study, 60 patients with unilateral hip osteoarthritis who underwent THR with intraoperative radiographic check with the conventional method (n = 30, control group) or the new method (AGFA flat panel DR14eG™/Orthosize™, n = 30, case group) were evaluated and compared for operation time, intraoperative changes in size/placement of the components and final radiological outcome (LLD, acetabular inclination and femoral offset) based on postoperative radiographs of the pelvis.

RESULTS

Mean operation time was lower in case group (85.3 min vs. 103.3 min, p value < 0.005), as well as mean absolute LLD (1.93 mm vs. 2.94 mm, p value = 0.242). There was a higher percentage of intraoperative changes in the offset of the prostheses' head (70% vs. 40%, p value = 0.018) and a significantly lower percentage of patients with LLD > 5 mm in the case group (0% vs. 27%, p value = 0.002).

CONCLUSIONS

This new method for the obtainment and assessment of intraoperative radiographs proved to be fast and assuring for keeping LLD below 5 mm in all patients.

Does the use of intraoperative fluoroscopy improve postoperative radiographic component positioning and implant size in total hip arthroplasty utilizing a direct anterior approach?

Background

The direct anterior approach (DAA) for total hip arthroplasty (THA) has gained recent popularity, with 1 purported benefit being access to intraoperative fluoroscopy. However, there are limited data demonstrating improved component position with the use of intraoperative fluoroscopy. The aim of this study is to compare radiographic implant positioning on 2 consecutive cohorts of patients undergoing DAA THA performed by 1 surgeon either utilizing intraoperative fluoroscopy or not. We hypothesized that there would be no relevant radiographic differences between the cohorts.

Methods

Forty-two consecutive patients underwent DAA THA utilizing fluoroscopy (IFC), and 42 consecutive patients then underwent DAA THA without fluoroscopy (NFC). Using preoperative pelvis radiographs and 6-week postoperative pelvis radiographs, acetabular anteversion, inclination, femoral offset, and templated component sizes vs final intraoperatively selected sizes were recorded and compared between cohorts.

Results

Acetabular inclination was 45.0° for IFC and 45.6° for NFC (P = .629). Femoral offset difference preoperatively and postoperatively was 0.8 mm for IFC and 1.3 mm for NFC (P = .734). Number of hips within the so-called safe zone was 32 for IFC and 33 for NFC (P = .794). These all demonstrated no significant difference between the cohorts. However, acetabular anteversion was 13.7° for IFC and 11.2° for NFC (P = .02).

Conclusions

In this limited series, the routine use of intraoperative fluoroscopy did not improve implant positioning or sizing. This may be surgeon-specific or due to the result of the use of acetabular landmarks to guide placement of the components without fluoroscopy.

Total Hip Arthroplasty Through the Direct Anterior Approach Using a Bikini Incision Can Be Safely Performed in Obese Patients

BACKGROUND

Direct anterior approach (DAA) total hip arthroplasty can be performed through a traditional vertical incision or a horizontal (bikini) incision. The purpose of this study is to compare the 2 approaches, performed by a single surgeon past the learning curve, in terms of (1) overall wound complications and (2) patient-reported esthetics at the 6-month follow-up.

METHODS

A case-control retrospective study was conducted. Eighty-six bikini DAA patients were matched 3:1 to 230 conventional DAA patients for gender, age, body mass index (BMI), and American Society of Anesthesiologists score. Outcomes evaluated included wound complications, acute periprosthetic joint infection, transfusion, length of surgery, and dysesthesia. A subgroup analysis was also performed on obese patients, BMI greater than 30 kg/m². Furthermore, the patients rated cosmesis of the incision at 6 months using a Patient Scar Assessment Scale and the Vancouver Scar Assessment Scale.

RESULTS

Bikini patients had lower rates of delayed wound healing compared to conventional incision (2.3% vs 6.1%, P = .087). This difference was statistically significant (0% vs 16.6%, P < .05) in obese patients. There was no difference in terms of incision cosmesis between the 2 incision types.

CONCLUSION

Our study demonstrates that the DAA total hip arthroplasty can be performed safely through an alternative horizontal bikini incision with complication rates equivalent to conventional incision DAA and to those in other approaches when performed by surgeons in a high volume, efficient hip replacement institution. In patients whose BMI is >30, a potential benefit of the horizontal incision may be lower wound complications. This study design should be performed at other institutions and ideally at a multi-institution level to evaluate if results can be corroborated. Our opinion is that the horizontal bikini incision should be utilized but only after mastery of the DAA approach using the conventional vertical incision.

Comparative outcomes between collared versus collarless and short versus long stem of direct anterior approach total hip arthroplasty: a systematic review and indirect meta-analysis

INTRODUCTION

Early research shows several advantages of the direct anterior approach (DAA) in THA that claimed to be as effective but less invasive than the posterior approach. However, due to the difficult femoral exposure and possible complications related to femoral preparation, this approach may result in a higher rate of undersized stems when compared to other approaches. The present authors believe that the femoral implant design (collar or collarless stem, short or long stem) in a collared femoral stem may relate to lower rates of stem subsidence and limb length discrepancy (LLD) in mid-term to long-term follow-up when compared to collarless femoral stems. However, currently, there is no consensus as to which femoral implant design is the most suitable for DAA in THA.

METHODS

This systematic review and meta-analysis aim to assess and compare postoperative complications (neurapraxia, wound infection, LFCN, hematoma, artery injury, cup malposition, embolism, fracture and implant loosening) and revision rates due to dislocation, periprosthetic fracture and implant migration after DAA using collared compared to collarless femoral stem and short femoral stem compared to long femoral stem in THA. These clinical outcomes consist of the postoperative complications and revision femoral stem due to neurapraxia, wound, LFCN and LLD. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Relevant studies that reported postoperative complications and revision of either implant were identified from Medline and Scopus from inception to June 6, 2018. Thirty-four studies were included for the analysis of DAA in THA; 23 studies were retrospective cohorts, four studies were prospective cohorts, and seven studies were RCTs. Thirty-one studies and three studies were included for analysis of collarless and collared femoral stems. Twenty-six studies were long femoral stems and eight studies were short femoral stems. Overall, there were 6825 patients (6457 in the collarless group and 368 in the collared group, 4280 in long stem and 2545 in short stem). A total of 469 and 66 patients had complications and revisions in the collarless group, and no patient had complications and revisions in the collared stem group. The total complication and revision rate per patient were 5% (95%CI 3.3%, 7%) and 0.9% (95%CI 0.6%, 1.2%) in all patients. The complication rate and revision rate were 5.7% (95%CI 3.8%, 7.7%) and 0.9% (95%CI 0.6, 1.2) in the collarless group. There was no prevalence of complications and revisions in the collared stem group. The complication rate and revision rate were 10.2% (95%CI 9%, 11.4%), 0.7% (95%CI 0.3%, 1%) and 5.2% (95%CI 3.1, 7.2), 1.5% (95%CI 1%, 2%) in short and long femoral stems, respectively. Indirect meta-analysis shows that collared femoral stem provided a lower risk of complications of 0.02 (95%CI 0.001, 0.30) when compared to collarless femoral stem. Long femoral stems had a lower risk of having complications of 0.57 (95%CI 0.48, 0.68) when compared to short femoral stems. In terms of revision, there is no statistically significant difference in collared femoral stem compared to collarless femoral stem and long femoral stem compared to short femoral stem.

CONCLUSION

In DAA THA, collared femoral stem and long femoral stem had decreased complication rates when compared to collarless femoral stem and short femoral stem by both direct and indirect meta-analysis methods. However, in terms of revision rates, there were no differences between all femoral stems (short versus long and collared versus collarless). Prospective randomized controlled studies are needed to confirm these findings as the current literature is still insufficient.