Transitioning the total hip arthroplasty technique from posterior approach in lateral position to direct anterior approach in supine position-risk factors for acetabular malpositioning and the learning curve

Direct Anterior Approach "No Trial Reduction Technique" in Bipolar Hemiarthroplasty for Treatment of Osteoporotic Femoral Neck Fracture: Surgical Techniques and Case Series

Bipolar hemiarthroplasty (BHA) for osteoporotic femoral neck fractures has a risk of proximal femoral fracture during trials, especially with larger trial bipolar shells. This study introduces a novel technique for BHA via the direct anterior approach, aiming to reduce trial use and lower the risk of iatrogenic femoral fractures. The "no trial reduction technique" involves positioning only the trial neck segment against the acetabulum's me-dial wall, without the bipolar shell and trial head. Fluoros-copy measures limb length differences to determine optimal femoral head and bipolar shell thickness, resulting in comparable limb lengths without early complications. [Orthopedics. 2025;48(2):74-78.].

Factors associated with mechanical complications following primary total hip arthroplasty through a modified direct anterior approach using custom stems

PURPOSE

To determine the rate and risk factors of mechanical complications (MCs) within two years following total hip arthroplasty (THA) through direct anterior approach (DAA) using custom stems, and to compare findings to other surgical approaches in the literature.

METHODS

The study included a consecutive series of 479 patients (529 hips) that had undergone primary THA through the DAA using uncemented custom stems between 02/2014 and 04/2017. There were 301 men and 228 women, with a mean age of 55.9 ± 11.6, and a mean body mass index (BMI) of 25.8 ± 4.3 kg/m2. All patients were contacted by phone at a minimum follow-up of two years, and those who reported complications were prescribed radiographic imaging and asked to attend clinical assessment. MCs were defined as periprosthetic fracture, aseptic loosening, dislocations, prosthesis failure, prosthesis malposition, or subsidence.

RESULTS

At two years follow-up, the rate of MCs was 3.2% (17 hips).The MCs comprised four femoral fractures, three aseptic stem loosening, three cup malpositions, three subsidences, two acetabular fractures, one stem malposition, and one dislocation. Ten hips (1.9%) required revision due to MCs. Compared to patients with no MCs, patients with MCs had significantly greater native femoral anteversion (16.7 ± 7.5º vs. 21.1 ± 9.7º, p = 0.042), more Charnley class C (13% vs. 41%, p = 0.008), fewer diameter 36 mm heads (45% vs. 18%, p = 0.044), and performed less intense physical activity (49% vs. 12%, p = 0.006) and sports (66% vs. 35%, p = 0.048). Multivariable analyses suggested that MCs were associated with greater native femoral anteversion (Odds Ratio [OR] = 1.08, p = 0.020) and Charnley class C (OR = 3.47,p = 0.027), but were inversely associated with intense physical activity (OR = 0.19, p = 0.047).

CONCLUSION

The rate of MCs within 2 years following THA through DAA using custom stems was 3.2% and the rate of revision due to MCs was 1.9%, which is within the range reported in the literature on other surgical approaches for THA. Furthermore, the presence of MCs was associated with greater native femoral anteversion and Charnley class C, but was inversely associated with intense physical activity.

Learning curve and initial outcomes of a novel percutaneously endoscopic-assisted total hip arthroplasty through mini bikini direct anterior approach: an observational cohort study

OBJECTIVE

Although the direct anterior approach can reduce muscle damage and ensure accurate prosthesis placement, the steep learning curve and increased risk of complications associated with DAA necessitate careful consideration. Therefore, we describe a technique for a novel percutaneously endoscopic-assisted total hip arthroplasty through mini bikini direct anterior approach (mDAA) and report the learning curve and initial outcomes.

METHODS

The first 125 THA performed by a single surgeon between September 2020 and February 2022 using the anterior approach were included, comprising the initial 41 cases of bikini DAA (bDAA) and the subsequent 84 cases of mDAA. Outcome measures included perioperative outcomes and postoperative complications. The cumulative sum analysis (CUSUM) was used to determine the learning curve of anterior approach THA for each patient's ORT. Multivariable analysis was performed to determine risk correlation.

RESULTS

A total of 125 anterior approach THA completed between 2020 and 2022 were identified. Among these, 41 were performed via bDAA and 84 via mDAA. No statistically significant differences were observed between the groups in terms of age, gender distribution, BMI or follow-up time. A significant reduction in ORT was noted, from 140 min for bDAA to 130 min for mDAA. Furthermore, there was a consistent decrease in LOI, LOS, and wound-healing problems. There was no statistically significant difference between groups with respect to Harris Hip Scores and other postoperative complications. The curve inflection points of the learning curve for the bDAA and mDAA group were located in the 22nd and 68th cases, respectively. The reduction of hemoglobin indicated a predicted increase in ORT.

CONCLUSIONS

In this study, ORT, LOI, LOS, and wound-healing problems decreased overall in mDAA group. After mastering the bDAA technique, approximately 27 mDAA cases are needed to acquire proficiency in this technique. Hence, mDAA is a valuable alternative for those seeking smaller incisions, resolving wound healing problems, and aiming for enhanced recovery after surgery.

Optimal hip capsular release for joint exposure in hip resurfacing via the direct anterior approach

Aims

Surgical approaches that claim to be minimally invasive, such as the direct anterior approach (DAA), are reported to have a clinical advantage, but are technically challenging and may create more injury to the soft-tissues during joint exposure. Our aim was to quantify the effect of soft-tissue releases on the joint torque and femoral mobility during joint exposure for hip resurfacing performed via the DAA.

Methods

Nine fresh-frozen hip joints from five pelvis to mid-tibia cadaveric specimens were approached using the DAA. A custom fixture consisting of a six-axis force/torque sensor and motion sensor was attached to tibial diaphysis to measure manually applied torques and joint angles by the surgeon. Following dislocation, the torques generated to visualize the acetabulum and proximal femur were assessed after sequential release of the joint capsule and short external rotators.

Results

Following initial exposure, the ischiofemoral ligament (7 to 8 o'clock) was the largest restrictor of exposure of the acetabulum, contributing to a mean 25% of overall external rotational restraint. The ischiofemoral ligament (10 to 12 o'clock) was the largest restrictor of exposure of the proximal femur, contributing to 25% of overall extension restraint. Releasing the short external rotators had minimal contribution in torque generated during joint exposure (≤ 5%).

Conclusion

Adequate exposure of both proximal femur and acetabulum may be achieved with minimal torque by performing a full proximal circumferential capsulotomy while preserving short external rotators. The joint torque generated and exposure achieved is dependent on patient factors; therefore, some cases may necessitate further releases.

Image-based robotic-assisted total hip arthroplasty through direct anterior approach allows a better orientation of the acetabular cup and a better restitution of the centre of rotation than a conventional procedure

PURPOSE

The aim was to investigate the contribution of robotics assisted total hip arthroplasty (THA) through direct anterior approach (DAA) in improving radiographic precision, functional results and complications.

METHODS

This retrospective study compared 100 primary conventional THA (cTHA) to 50 primary robotic THA (rTHA) through DAA. All cups were placed with the objective of having no anterior overhang while respecting the safe zones (SZ). Radiographic analysis included cup inclination and anteversion, vertical and horizontal changes of the rotation centre (ΔVCOR, ΔHCOR), acetabular and femoral offset. SZ were 30-50° of inclination and 10-30° of anteversion. Outliers were defined as medial displacement of the COR > 5 mm, vertical displacement of the COR > 3 mm superiorly. Harris hip score (HHS) and complications were compared at one year of follow-up.

RESULTS

The robotic cups were better oriented with 98% in the global SZ versus 68% in the cTHA group (p = 0.0002). The COR was on average better restored in the robotic group in both the horizontal and vertical planes (Δ HCOR =  - 5.0 ± 5.0 vs - 3.4 ± 4.9, p = 0.03; Δ VCOR = 1.6 ± 3.3 vs 0.2 ± 2.7, p = 0.04). There were fewer outliers in the rTHA group concerning VCOR (28% versus 10%, p = 0.03). There was no significant difference in HHS and complication rate at one year.

CONCLUSION

The use of robotics for THA by DAA provided an advantage in controlling the orientation of the cup and the restoration of its rotation centre. Thanks to the 3D planning on CT scan, it allowed to respect the thresholds while avoiding the anterior overhangs.

No dislocation and low complication rate for a modern dual mobility cup with pre-impacted femoral head in primary hip replacement: A consecutive series of 175 hips at minimum 5-year follow-up

INTRODUCTION

Despite its excellent results in preventing dislocation, the dual mobility cup (DMC) is still struggling to be adopted by some teams due to premature wear and loosening reported on first-generation implants. Therefore, this study aimed to assess the mid-term survivorship of a modern DMC with a pre-impacted head and the radio-clinical results at a minimum follow-up of 5 years.

METHODS

This was a retrospective single-centre study performed on patients who had a primary total hip replacement for osteoarthritis in 2016. The cup was a third-generation DMC with a pre-impacted femoral head. Clinical (harris hip score (HHS)) and radiological (cup abduction, anteversion, overhang, and radiolucent lines) results were recorded, as well as complications, particularly dislocations and survivorship. A minimum of five years of follow-ups was required.

RESULTS

One hundred and seventy-five hips (167 patients) met the inclusion criteria. Five hips (2.9%, 5/175) were lost to follow-up and excluded from the postoperative analysis. The mean follow-up period was 70 ± 2.9 months [63.6-76.5]. Three cups needed revision surgery (1.8%, 3/170): one for septic loosening, and two for chronic infection. At 77 months, the global survival probability was 98.2% ± 1, and the survival probability excluding septic aetiology was 100%. There was a significant improvement in the HHS from pre-operatively (48.3 ± 6.0 [14.0-70.0]) to post-operatively (96 ± 4.5 [50-100]) (p < 0.0001). There were no postoperative dislocations recorded, nor any iliopsoas-impingement or symptomatic cam-effect.

DISCUSSION

This study showed excellent survival and good radiological and clinical results of this dual mobility cup at a mid-term follow-up. None of the patients had dislocation or any specific complication feared with dual mobility cups.

Compared learning curves of the direct anterior and anterolateral approach for minimally invasive hip replacement

Minimally invasive hip arthroplasty becomes increasingly popular. It is technically challenging and the approaches used are associated with a considerable learning curve. This nurtures concerns regarding patient safety, surgical training, and cost effectiveness. Consequently, we initiated a study comparing the learning curves of a supervised trainee surgeon utilizing both the anterolateral and direct anterior approach (DAA) when introduced to minimally invasive hip replacement surgery. Outcome measurements included the Harris hip score (HHS), cup inclination and anteversion, offset and leg length, stem placement, surgical time and complications. Time from incision to suture decreased significantly over time but did not differ between both groups. The functional outcomes (HHS) after six weeks and three months were comparable (p=0.069 and 0.557) and within the expected range equalling 90.3 (anterior) and 89.2 (anterolateral) points. With both approaches safe component placement was readily achieved. Both offset and leg length, however, were reconstructed more reliably with the DAA (p=0.02 and 0.001). A higher rate of dislocations was seen with the anterior, more perioperative infections with the anterolateral approach. We suggest that supervision by an experienced surgeon favourably influences the learning curves for both the minimally invasive DAA and anterolateral approach and conclude that the greatest improvement is seen within the first 60 cases.

Learning Curve of Total Hip Arthroplasty in Direct Anterior Approach without Requiring Corrective Osteotomy for Hip Dysplasia

OBJECTIVE

To explore the learning curve of total hip arthroplasty in direct anterior approach (DA-THA) without requiring corrective osteotomy for patients with unilateral developmental dysplasia of the hip (DDH) through the evaluation of clinical and radiographic results.

METHOD

From December 2015 to January 2021, we retrospectively evaluated a surgeon's first 100 patients with unilateral hip dysplasia (Crowe I-III) who underwent DA-THA. All procedures were performed by a fellowship-trained joint surgeon. Cementless hemispheric porous-coated acetabular cups and tapered cementless stems were used in all hips. The radiographic data, including leg length, the height of the center of rotation, femoral head offset, the cup anteversion and inclination angle, were measured. The cumulative sum analysis (CUSUM) and risk-adjusted cumulative sum analysis (RA-CUSUM) were used to determine the learning curve of DA-THA for each patient's operation time. By analyzing the operation time, complication rate, postoperative length of hospitalization and creatine kinase (before surgery and the third day after surgery), estimated blood loss, Harris score, radiographic data were compared between the different stages of the learning curve.

RESULTS

The mean follow-up time was 35.45 ± 16.82 months. The CUSUM method obtained the maximum turning point of the curve at 43 cases, which divided the learning curve into Learning Period and Mastery Period. The CUSUM learning curve was best modeled as a cubic curve with the equation: CUSUM (min) = 0.001x³  - 0.495x²  + 33.60x - 10.00, which had a higher R² value of 0.967. The pre-operative data, creatine kinase, estimated blood loss and postoperative Harris scores of the two stages were not statistically significant (P > 0.05). The mean operation time was 118 min in the Learning Period and 87 min in the Mastery Period. Statistically significant differences were detected in the operation time (P < 0.001), postoperative length of hospitalization(P = 0.024), and postoperative leg length discrepancy (P = 0.012) between the two stages. The overall complication rates were 27.9% in the Learning Period and 12.3% in the Mastery Period (p = 0.049). The overall outliers of radiographic data were 34 cases in the Learning Period and 31 cases in the Mastery Period (79.07% vs 54.39%, P = 0.010).

CONCLUSIONS

The DA-THA is a valuable alternative to achieve satisfactory clinical results for mild-to-moderate DDH patients. Furthermore, accurate analysis of the learning curve of DA-THA for hip dysplasia by the CUSUM method showed that the surgeons need to finish about 43 cases to master the technique.

The learning curve for the direct anterior total hip arthroplasty: a systematic review

BACKGROUND

The direct anterior approach (DAA) for total hip arthroplasty (THA) is a muscle-sparing approach thought to have less post-operative pain and quicker recovery, with similar functional outcomes to other approaches. However, it is technically challenging and transitioning surgeons may experience increased complication rates. The purpose of this systematic review is to identify reported learning curves associated with the DAA.

METHODS

Three databases (MEDLINE, Embase, and Web of Science) were searched using terms including "total hip arthroplasty," "direct anterior approach," and "learning curve." Study characteristics, patient demographics, learning curve analyses, and complications were abstracted.

RESULTS

Twenty-one studies met inclusion criteria, with a total of 9738 patients (60% female), an average age of 63.7 years (range: 13-94), body mass index of 27.0 kg/m2 (range: 16.8-58.9), and follow-up of 19 months (range: 1.5-100). There were five retrospective cohort studies and 13 case series representing fair methodological quality. Six studies depicted a true learning curve, with mean operative time of 156.59 ± 41.71 minutes for the first case, 93.18 ± 14.68 minutes by case 30, and 80.45 ± 12.28 minutes by case 100. Mean complication rate was 20.8 ± 12.7% in early groups and decreased to 7.6 ± 7.1% in late groups.

CONCLUSION

This review demonstrated a substantial learning curve associated with the DAA to THA. Operative time plateaued after approximately 100 cases. Complication rates decreased substantially from early to late groups.

Restoring hip biomechanics during the learning curve of a novice surgeon: Direct anterior approach vs posterior approach

Introduction

It remains controversial whether the direct anterior approach (DAA) or the posterior approach (PA) allows better restoration of hip biomechanics after total hip arthroplasty (THA). Besides, it is not certain which approach is best for a novice surgeon to avoid implant malposition, neither during the learning curve nor once the curve plateau has been reached.

Methods

We performed a retrospective cohort study of THAs operated on between 2014 and 2019 by a single novice surgeon (DAA, n = 187; PA, n = 184). The surgeon used both approaches, and thus went through parallel learning curves.

Results

While the DAA presented a greater number of acetabular cup implantations within Lewinnek's "safe zone" for inclination (84.5% vs. 79.3%; p = 0.003), the PA returned superior results for anteversion (77.7% vs. 68.4%; p = 0.000). The PA showed a tendency to verticalize acetabular cups, while the DAA tended to antevert them. The DAA resulted in fewer patients with leg length discrepancy (3.2% vs. 8.2%, p = 0.041). No differences were found in stem coronal alignment or femoral offset.

Conclusion

Both approaches are safe and reliable for restoring hip biomechanics through THA surgery during the learning curve of a novice hip surgeon. Similar radiological outcomes are also seen once the surgeon has reached the learning curve plateau.

Novel Radiographic Indexes for Elbow Stability Assessment: Part A-Cadaveric Validation

INTRODUCTION

Elbow bony stability relies primarily on the high anatomic congruency between the humeral trochlea and the ulnar greater sigmoid notch. No practical tools are available to distinguish different morphotypes of the proximal ulna and herewith predict elbow stability. The aim of this study was to assess inter-observer reproducibility, evaluate diagnostic performance and determine responsiveness to change after simulated coronoid process fracture for three novel elbow radiographic indexes.

METHODS

Ten fresh-frozen cadaver specimens of upper limbs from human donors were available for this study. Three primary indexes were defined, as well as two derived angles: Trochlear Depth Index (TDI); Posterior Coverage Index (PCI); Anterior Coverage Index (ACI); radiographic coverage angle (RCA); olecranon-diaphisary angle (ODA). Each index was first measured on standardized lateral radiographs and subsequently by direct measurement after open dissection. Finally, a type II coronoid fracture (Regan and Morrey classification) was created on each specimen and both radiographic and open measurements were repeated. All measurements were conducted by two orthopaedic surgeons and two dedicated musculoskeletal radiologists.

RESULTS

All three indexes showed good or moderate inter-observer reliability and moderate accuracy and precision when compared to the gold standard (open measurement). A significant change between the radiographic TDI and ACI before and after simulated coronoid fracture was observed [TDI: decrease from 0.45 ± 0.03 to 0.39 ± 0.08 (p = 0.035); ACI: decrease from 1.90 ± 0.17 to 1.58 ± 0.21 (p = 0.001)]. As expected, no significant changes were documented for the PCI. Based on these data, a predictive model was generated, able to identify coronoid fractures with a sensitivity of 80% and a specificity of 100%.

CONCLUSION

New, simple and easily reproducible radiological indexes to describe the congruency of the greater sigmoid notch have been proposed. TDI and ACI change significantly after a simulated coronoid fracture, indicating a good responsiveness of these parameters to a pathological condition. Furthermore, combining TDI and ACI in a regression model equation allowed to identify simulated fractures with high sensitivity and specificity. The newly proposed indexes are, therefore, promising tools to improve diagnostic accuracy of coronoid fractures and show potential to enhance perioperative diagnostic also in cases of elbow instability and stiffness.

LEVEL OF EVIDENCE

Basic science study.

CLINICAL RELEVANCE

The newly proposed indexes are promising tools to improve diagnostic accuracy of coronoid fractures as well as to enhance perioperative diagnostic for elbow instability and stiffness.

Novel Radiographic Indexes for Elbow Stability Assessment: Part B-Preliminary Clinical Study

INTRODUCTION

The coronoid process plays a key-role in preserving elbow stability. Currently, there are no radiographic indexes conceived to assess the intrinsic elbow stability and the joint congruency. The aim of this study is to present new radiological parameters, which will help assess the intrinsic stability of the ulnohumeral joint and to define normal values of these indexes in a normal, healthy population.

METHODS

Four independent observers (two orthopaedic surgeons and two radiologists) selected lateral view X-rays of subjects with no history of upper limb disease or surgery. The following radiographic indexes were defined: trochlear depth index (TDI); anterior coverage index (ACI); posterior coverage index (PCI); olecranon-coronoid angle (OCA); radiographic coverage angle (RCA). Inter-observer and intra-observer reproducibility were assessed for each index.

RESULTS

126 subjects were included. Standardized lateral elbow radiographs (62 left and 64 right elbows) were obtained and analysed. The mean TDI was 0.46 ± 0.06 (0.3-1.6), the mean ACI was 2.0 ± 0.2 (1.6-3.1) and the mean PCI was 1.3 ± 0.1 (1.0-1.9). The mean RCA was 179.6 ± 8.3° (normalized RCA: 49.9 ± 2.3%) and the mean OCA was 24.6 ± 3.7°. The indexes had a high-grade of inter-observer and intra-observer reliability for each of the four observers. Significantly higher values were found for males for TDI, ACI, PCI and RCA.

CONCLUSION

The novel radiological parameters described are simple, reliable and easily reproducible. These features make them a promising tool for radiographic evaluation both for orthopaedic surgeons and for radiologists in the emergency department setting or during outpatient services.

LEVEL OF EVIDENCE

Basic Science Study (Case Series).

CLINICAL RELEVANCE

The novel radiological parameters described are reliable, easily reproducible and become handy for orthopaedic surgeons as well as radiologists in daily clinical practice.

Greater trochanter fractures in the direct anterior approach: evolution during learning curve, risk factors and consequences

INTRODUCTION

Greater trochanter (GT) fractures affect 0.6-29% of patients after direct anterior approach (DAA) total hip arthroplasty (THA). Given the growing popularity of this approach, this study aimed to assess the evolution of the GT fractures during the learning curve, their risk factors and their consequences.

MATERIALS AND METHODS

537 total hip arthroplasties were retrospectively included from May 2013 to December 2017 in a single academic centre. Patient characteristics, perioperative management, clinical consequences and postoperative radiographs were analysed.

RESULTS

GT fractures represented 2.4% (n = 13) of the THA, and there was not a decrease with experience. The GT fracture patients did not require any additional support during the surgery, and full weight bearing was always allowed without any restriction. This complication only happened in females, with the risk significantly increased in those > 70 years old (OR = 4.9). There was no specific consequence during the follow-up, mean HHS score was 98.5 and all of the patients were satisfied or very satisfied postoperatively.

CONCLUSION

Older osteoporotic women are known to be at risk for GT fracture during DAA THA. Those results reinforce the argument in favour of proper patient selection in DAA to lower the complications since it does not improve with surgeon's experience.

LEVEL OF EVIDENCE

Retrospective, consecutive case series; Level IV.

Effects of body mass index and range of motion on intraoperative change in pelvic tilt during total hip arthroplasty using the direct anterior approach

BACKGROUND

Intraoperative pelvic tilt changes that occurs during total hip arthroplasty (THA) in the supine position affects cup placement and sometimes causes malalignment. The relationship between body mass index (BMI) and pelvic movement has been reported for some procedures, but not the direct anterior approach (DAA). The purpose of this study was to investigate intraoperative pelvic tilt changes that occurs during DAA.

METHODS

In this single-center, retrospective study, we reviewed 200 hips that underwent primary THA via DAA in the supine position using an accelerometer-based navigation system. Intraoperative changes in pelvic tilt and axial rotation from the start of surgery to cup placement were assessed using the navigation system. Preoperative clinical factors that increased pelvic tilt and axial rotation toward the surgical side by > 10° were analyzed via univariate and multiple logistic regression analyses.

RESULTS

The mean pelvic tilt value increased by 7.6° ± 3.8° (95% confidence interval [CI], 7.1-8.2; range, - 5.0-19.0) intraoperatively, and the axial rotation increased by 3.2° ± 2.7° (95% CI, 2.7-3.7; range, - 13.0-12.0). Univariate analysis revealed that the group with increased pelvic tilt showed significantly greater range of abduction and internal rotation, and significantly lower BMI than the group with no increased tilt. Pre-incisional pelvic tilt was significantly greater in the group with increased axial rotation than in the group with no increased rotation. On logistic regression analysis, BMI (odds ratio [OR], 0.889; 95% CI, 0.809-0.977; p = 0.014) and the range of internal rotation (OR, 1.310; 95% CI, 1.002-1.061; p = 0.038) were predictors of large increases in pelvic tilt. No predictors of large increases in axial rotation were identified.

CONCLUSION

Significant forward pelvic tilt was observed in patients with a low BMI values and high ranges of internal rotation via THA using the DAA. Findings indicated that surgeons should pay attention to intraoperative pelvic movements, which may help identify patients with significant pelvic tilt changes.

Imaging Analysis of Prosthesis Angle after Hip Replacement with Direct Anterior Approach in Lateral Position

The use of lateral DAA-THA for the treatment of end-stage hip disorders has good recent clinical efficacy, does not require special surgical beds and traction equipment, uses traditional surgical instruments, reduces the requirements for surgical beds and surgical instruments, enters through the nerve and muscle anatomical gap without cutting any muscle or nerve tissue, is minimally invasive, and has good surgical maneuverability, low bleeding, low postoperative pain, short hospitalization time, and rapid recovery. It is a safe and effective minimally invasive procedure because of its light weight, short hospital stay, and rapid recovery. In this paper, we used imaging to observe the angle of the posterior prosthesis. And the results showed that hip arthroplasty using the direct anterior approach improved hip mobility in early stages compared with other approaches and reduced pain. The direct anterior approach and length between total hip arthroplasty using direct lateral and posterior lateral approach and partial data (surgical time, blood loss, etc.) were significantly worse than those using direct forward approach. In addition, the direct anterior approach to total hip arthroplasty is subject to a learning curve and requires at least 33 cases of experience to achieve a lower complication rate.

Robotics and Navigation as Learning Tools for Fellows Training in Hip Arthroplasty

INTRODUCTION

The association between implant malpositioning and complications has been repeatedly demonstrated. Recently, technological advancements have allowed for more consistent implant placement. Beyond this obvious application, these technologies may also serve as a learning tool. Thus, the aim of this study was to evaluate the accuracy of fellows' estimation of implant positioning using a robotic system.

METHODS

Data were prospectively collected for all patients undergoing total hip arthroplasty between September 2019 and December 2019. The fellow was blinded to the robotic system. Before reaming and broaching by the senior surgeon, the fellow was asked to place the reamer at 40° of cup inclination and 20° of version. The resulting values were recorded before the true measurements were revealed. A similar process was followed for femoral broaching.

RESULTS

The mean difference between the estimated and actual cup inclination and version was 7.24° (P = 0.060) and 4.81° (P = 0.031), respectively. The mean difference in broach version was 7.00° (P = 0.159). Without the robotic system, 43.47% and 69.57% of patients would have had the cup placed outside of the safe zones described by Lewinnek and Callanan, respectively.

CONCLUSION

The estimated anteversion of the acetabular implant was found to be markedly different from its actual anteversion. A considerable portion of the cups would have been positioned outside of the Lewinnek and Callanan "safe zones" provided that the implants would have been manually positioned. The use of robotic or navigation systems may provide useful learning tools for fellows in training to understand their own inaccuracies in estimated implant position and hence refine their abilities.

Risk factors for femoral fracture in lateral decubitus direct anterior approach total hip arthroplasty using conventional stems: a retrospective analysis

OBJECTIVE

To provide guidelines for surgery and reduce the incidence of fracture, this study analyzed the relationship between femoral fracture and related factors in direct anterior approach (DAA) total hip arthroplasty (THA) in the lateral decubitus position.

METHOD

A retrospective series of 273 consecutive patients who underwent THA with the DAA in the lateral decubitus position was analyzed. Each surgery was performed by the same surgeon with a conventional operation bed and femoral stem. The correlations between the incidence of fracture and sex, age, body mass index (BMI), height, osteoporosis, the anterior superior iliac spine-greater trochanter distance (ASIS-GTD), and hip joint disease were analyzed by univariate analysis and logistic regression analysis.

RESULTS

Among all hip arthroplasty procedures, 35 hips had femoral fractures, including 30 greater trochanter fractures, 4 proximal femoral splits, and 1 femoral perforation. The incidence of fracture was 12.82%. Univariate analysis showed no significant difference in the incidence of fracture by sex, BMI, or age. However, osteoporosis caused an increase in the incidence of fracture, while the incidence of fracture decreased as height and the ASIS-GTD increased. The incidence of femoral neck fracture was lower in cases of osteonecrosis of the femoral head than in cases of other diseases. Logistic regression showed a significant correlation between osteoporosis, the ASIS-GTD, and fractures. Patients with osteoporosis had a high possibility of fracture (OR = 2.414); the possibility of fracture decreased with increasing ASIS-GTD (OR = 0.938).

CONCLUSION

Lateral decubitus DAA THA can be successfully performed using a conventional operation bed and stem, effectively saving medical resources. Osteoporosis and a shorter ASIS-GTD were independent risk factors for femoral fracture.