Direct Anterior Total Hip Arthroplasty Research Articles

The Impact of Total Hip Arthroplasty Surgical Approach on Patient-Reported Outcomes Measurement Information System Computer Adaptive Tests of Physical Function and Pain Interference

BackgroundThe present study examines Patient Reported Outcomes Measurement Information System (PROMIS) Computer Adaptive Test (CAT) scores for domains of physical function (PF) and pain interference (PI) in patients undergoing elective THA from either a direct anterior or posterior surgical approach. MethodsA total of 1358 patients who underwent THA at our institution from 1/1/2015 to 12/1/2018 were identified. Visual analog scale (VAS) pain scores, PROMIS CAT PF and PI data were collected at the last preoperative visit as well as 6 weeks, 6 months, and 1-2 years postoperatively. Literature-derived minimum clinically important difference (MCID) for PROMIS CAT PF metric with regard to THA was used for data comparison. ResultsFour hundred nine patients were included in the final analysis. Fifty-one percent underwent a posterior approach, and 49% underwent a direct anterior approach. Both approaches led to a significant improvement in PROMIS CAT PF and PI scores. Patients undergoing a direct anterior approach had significantly higher preoperative and postoperative PROMIS CAT PF scores as well as significantly lower preoperative PROMIS CAT PI scores. Each approach yielded similar interval improvements of PROMIS CAT PF and PI. One hundred three direct anterior approach THA patients (51%) and 119 posterior approach THA patients (57.5%) achieved PROMIS PF MCID at 1- to 2-year follow-up. ConclusionNeither the direct anterior nor posterior THA surgical approach conferred an advantage to postoperative improvements of PROMIS CAT PF and PI scores. Adult reconstructive surgeons should continue to execute the direct anterior or posterior THA surgical approaches based upon personal preference. Despite surgeon confidence in THA, the potential for further innovation exists given the number of THA patients who failed to achieve PROMIS PF MCID.

Intraoperative Fluoroscopy Improves Recreation of Femoral Offset but not Leg Lengths during Direct Anterior Total Hip Arthroplasty

Postoperative leg length discrepancy (LLD) and increased femoral Offset (FO) after total hip arthroplasty (THA) are frequently cited reasons for decreased patient satisfaction and litigation. Minimizing LLD and recreating FO can be challenging and different approaches exist. Some surgeons perform total hip arthroplasty from a direct anterior approach (DAA) utilizing intraoperative fluoroscopyto minimize potential for LLD and changes in FO.

Surgical automation reduces operating time while maintaining accuracy for direct anterior total hip arthroplasty

ObjectiveInvestigate the efficiency/accuracy of surgical automation versus manual component implantation in DA THA. MethodsRetrospective review of 111 hips: 51 hips via automation and 60 hips via manual technique for DA THA. ResultsOR time averaged 8 min faster in the Automated group, compared to Manual group (p = 0.0009). Average femoral size was one size larger in the Automated group compared to Manual group (p = 0.007). No clinically significant differences were found between Manual and Automated groups for cup position or limb-length discrepancy. One calcar fracture occurred in the Automated group. ConclusionSurgical automation is efficient and accurate for DA THA.

Short-Term Radiographic Evaluation of a Tri-Tapered Femoral Stem in Direct Anterior Total Hip Arthroplasty

Direct anterior approach (DAA) total hip arthroplasty (THA) has become increasingly popular, largely due to utilization of a true internervous and intermuscular plane. However, recent literature has demonstrated an increased rate of femoral implant subsidence with this approach. Hence, different femoral implants, such as the tri-tapered femoral stem, have been developed to facilitate proper component insertion and positioning to prevent this femoral subsidence. The purpose of this study was to evaluate the subsidence rate of a tri-tapered femoral stem implanted utilizing a DAA, and to determine if the proximal femoral bone quality affects the rate of subsidence. A retrospective analysis of 155 consecutive primary THAs performed by a single surgeon was conducted. Age, gender, primary diagnosis, and radiographic measurements of each subject were recorded. Radiological evaluations, such as bone quality, femoral canal fill, and implant subsidence, were measured on standardized anteroposterior (AP) and frog-leg lateral radiographs of the hip at 6-week and 6-month postoperative follow-up evaluations. The average subsidence of femoral stems was 1.18 ± 0.8 mm. There was no statistical difference in the amount of subsidence based on diagnosis or proximal femora quality. The tri-tapered stem design consistently filled the proximal canal with an average of 91.9 ± 4.9% fill. Subsidence was not significantly associated with age, canal flare index (CFI), or experience of the surgeon. THA utilizing the DAA with a tri-tapered femoral stem can achieve consistent and reliable fit regardless of proximal femoral bone quality.

Hidden blood loss in direct anterior total hip arthroplasty: a prospective, double blind, randomized controlled trial on topical versus intravenous tranexamic acid.

Despite a plethora of literature reporting on the use of tranexamic acid (TXA) in total hip arthroplasty (THA), little is available on its effect on post-operative hidden blood loss and even less on its use in the direct anterior approach (DAA), which is gaining popularity. This study was designed as a prospective, double blind, single centre, randomized controlled trial. Sixty patients were allocated to intravenous administration of 1.5g of TXA just before wound closure while 60 patients were allocated to topical application of 3.0g of TXA via a subfascial drain at the end of the procedure. Post-operative blood loss was (1) calculated via a well-established formula based on pre- and post-operative Hb levels, patients characteristics and intra-operative blood loss and (2) measured via the amount that collected in the subfascial drain over time. No statistical significant difference in post-operative blood loss was found, neither when the formula was used (0.55L [topical] vs 0.67L [IV]; p = .140) nor when looking at the drain output (0.25L [topical] vs 0.29L [IV]; p = .108). No significant difference in secondary outcome measures, such as transfusion of units of packed red blood cells, length of hospital stay or the occurrence of venous thromboembolisms, could be found either. This study provides detailed insights into the intra- and post-operative blood loss in DAA THA and shows that topical and IV TXA have similar effects on hidden blood loss. Clinical Trial Number: NCT01940692. Level I-Randomized Controlled Trial.

Safely Implementing the Direct Anterior Total Hip Arthroplasty: A Methodological Approach to Minimizing the Learning Curve

Orthopaedic surgeons often cite concern for a learning curve as a barrier to adopting the direct anterior approach (DAA) for total hip arthroplasty (THA) while transitioning from other approaches. Studies both assessing and describing a practical approach and strategy to safely accomplish this transition, as well as the effect on clinical outcomes, are not well described. This prospective study compares a single surgeon's operative results and complications for the first consecutive 100 direct anterior THA to the last 100 consecutive posterior THA after 7 years in practice. The regimented and disciplined learning strategy used to implement the DAA is detailed in this study. The data were analyzed using univariate and multivariate regression models. Univariate analyses identified significant differences in sex, age, Asian race, and diagnostic cause for THA between the two cohorts. Multivariate analyses controlled for these differences and showed that relative to posterior THA, direct anterior THA cases were associated with 7-minute longer procedures (P = 0.002) and lengths of stay that were 0.7 days fewer (P = 0.013). No significant differences were present in the estimated blood loss, and importantly, no significant differences in death or surgical complication rates between cohorts. This study suggests that the DAA for THA can be safely implemented without the increased and adverse risk to the patient when a structured learning process is maintained and meticulously performed.

Augmented Reality for Acetabular Component Placement in Direct Anterior Total Hip Arthroplasty

BackgroundMalposition of the acetabular component of a hip prosthesis can lead to poor outcomes. Traditional placement with fluoroscopic guidance results in a 35% malpositioning rate. We compared the (1) accuracy and precision of component placement, (2) procedure time, (3) radiation dose, and (4) usability of a novel 3-dimensional augmented reality (AR) guidance system vs standard fluoroscopic guidance for acetabular component placement. MethodsWe simulated component placement using a radiopaque foam pelvis. Cone-beam computed tomographic data and optical data from a red-green-blue-depth camera were coregistered to create the AR environment. Eight orthopedic surgery trainees completed component placement using both methods. We measured component position (inclination, anteversion), procedure time, radiation dose, and usability (System Usability Scale score, Surgical Task Load Index value). Alpha = .05. ResultsCompared with fluoroscopic technique, AR technique was significantly more accurate for achieving target inclination (P = .01) and anteversion (P = .02) and more precise for achieving target anteversion (P < .01). AR technique was faster (mean ± standard deviation, 1.8 ± 0.25 vs 3.9 ± 1.6 minute; P < .01), and participants rated it as significantly easier to use according to both scales (P < .05). Radiation dose was not significantly different between techniques (P = .48). ConclusionA novel 3-dimensional AR guidance system produced more accurate inclination and anteversion and more precise anteversion in the placement of the acetabular component of a hip prosthesis. AR guidance was faster and easier to use than standard fluoroscopic guidance and did not involve greater radiation dose.

Using the anterior capsule of the hip joint to protect the tensor fascia lata muscle during direct anterior total hip arthroplasty: a randomized prospective trial

BackgroundThe direct anterior approach for total hip arthroplasty (THA) has specific advantages, but injury to the tensor fasciae lata muscle (TFLM) remains a concern. This injury in part negates some of the advantages of the intermuscular approach, because injury of the muscle fibers of the TFLM can lead to less satisfactory clinical results. Thus, in this study, we propose an intraoperative method to protect the TFLM and demonstrate its feasibility.MethodsFifty-six patients undergoing THA by the direct anterior approach were divided randomly into two groups. In group A, the TFLM was protected by an autogenous tissue “pad” created from the anterior capsule of the joint which protect the TFLM from direct contact with the retractors. In group B, the operation was carried out with no protection of the TFLM except the attempt by the surgeons to consciously avoid injury of the TFLM. We evaluated magnitude of changes in the muscle cross-sectional area (MSCA) and fatty atrophy (FA) by magnetic resonance imaging. The differences in blood hemoglobin and serum levels of myoglobin, lactate dehydrogenase (LDH), and creatine phosphokinase (CPK) were compared at different time, postoperatively. The Harris hip score, postoperative drainage volume and visual analogue scores (VAS) were compared between the two groups.ResultsLDH, CPK and myoglobin in group B were significantly higher than group A at 8, 24, and 48 h after the surgery. (p < 0.05) Compared to the group A, the decrease of hemoglobin in group B displayed significantly at 24 and 48 h after surgery. (P < 0.05) The significantly increased MSCA and FA of TFLM were demonstrated in group B. The PDV and VAS in group B were significantly higher than group A. (P < 0.05) The Harris score in group A was significantly higher than group B (P < 0.05) one month after surgery, but there was no significant difference six months later.ConclusionsUsing the anterior capsule of the hip joint as an autogenous, protective capsular tissue pad to limit the trauma to the TFLM during a direct anterior approach to THA is an effective method to protect the TFLM and improve the clinical effect.Trial registrationChiCTR: ChiCTR1900025173. Retrospectively registered August 15, 2019.

Smoking Is a Risk Factor for Wound Complications after Direct Anterior Hip Arthroplasty with Mesh Tape Closure

To determine what factors increase the risk of early wound complications in patients undergoing direct anterior total hip arthroplasty whose wounds were closed with 2-octyl cyanoacrylate with mesh. This study was a retrospective review of 75 consecutive patients who underwent direct anterior total hip arthroplasty closed with 2-octyl cyanoacrylate with mesh. Of 29 patients who were smokers, five patients (17.2%) developed a wound complication, whereas out of 46 nonsmokers, only one patient (2.2%) developed a wound complication (P = .029). The authors recommend a closure technique that sufficiently protects the wound during healing, as well as preoperative patient optimization and smoking cessation.

Surgical Approach to Total Hip Arthroplasty Affects the Organism Profile of Early Periprosthetic Joint Infections.

Background:The optimal approach for total hip arthroplasty (THA) remains hotly debated. While wound complications following the direct anterior approach are higher than with other approaches, the organism profile of periprosthetic joint infections (PJIs) by approach remains unknown. Our goal was to compare the organism profiles of PJIs following direct anterior and non-anterior THA.Methods:We retrospectively reviewed 12,549 primary THAs (4,515 direct anterior and 8,034 non-anterior) that had been performed between January 2012 and September 2019 at a university-affiliated single-specialty orthopaedic hospital to identify patients with an early postoperative PJI. Criteria used for the diagnosis of a PJI were the National Healthcare Safety Network, which screens for PJI that occurs within 90 days of index arthroplasty, and the Musculoskeletal Infection Society guidelines. Patient demographic information and organism characteristics were recorded for analysis.Results:We identified 84 patients (38 who underwent the direct anterior approach and 46 who underwent the non-anterior approach) with an early postoperative PJI following primary THA (0.67% total THA PJI rate, 0.84% direct anterior THA PJI rate, and 0.57% non-anterior THA PJI rate). The direct anterior THA cohort had a significantly lower body mass index and American Society of Anesthesiologists score than the non-anterior THA cohort (29.5 versus 35.2 kg/m2, p < 0.0001; 2.29 versus 2.63, p = 0.016, respectively). Regarding organism profile, patients in the direct anterior THA cohort had significantly more monomicrobial gram-negative infections than the non-anterior THA cohort (4 versus 0, p = 0.038). We did not identify any demographic risk factors other than approach for gram-negative PJI. There were no significant differences in methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, coagulase-negative Staphylococcus, obligate anaerobes, polymicrobial, or PJIs due to other organisms by approach.Conclusions:Direct anterior THA approaches have a greater risk of monomicrobial gram-negative PJI, likely due to the unique microbiome of the inguinal region. While targeted infection prophylaxis may reduce these infections, it is not entirely effective on its own. Future studies with larger sample sizes are required to help us develop more targeted perioperative infection prophylaxis.Level of Evidence:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Direct anterior total hip arthroplasty: a retrospective study

Background:The quest for less invasive surgical approaches for total hip arthroplasty has gained much attention recently. There is very little information regarding differences about the main surgical access. The purpose of this study was to collect data regarding patients’ subjective perceptions of the direct anterior hip arthroplasty, heterotopic ossification degrees, range of movement and complication and comparing these satisfaction results with the other surgical techniques.Methods:The study involved 51 patients operated in our Orthopedic clinic with direct anterior total hip arthroplasty between 2016 and 2017. We recorded and compared clinical and radiographic data at 1 year with anterolateral hip arthroplasty.Result:Only one patient described less than an 8/10 satisfaction; 5.45% of the patients restored the physiological ROM and 21.82 % lost only 5° of range of motion. According to Brooker Classification 58.33 % did not develop any Heterotopic Ossification.Conclusion:All standard approaches to the hip have been shown to be safe and efficacious, with particular advantages and disadvantages for each approach. DAA has some short term advantages like a faster recovery, less blood loss and less heterotopic ossification. Long term studies are required to demonstrate a cost benefit or quality of care advantage to other hip approaches. (www.actabiomedica.it)

Quantitative characterisation of impaction events during femoral broaching in total hip arthroplasty

Total hip arthroplasty (THA) broaching involves impacting a broach handle with a mallet, facilitating force transmission to progress broaches into the femoral medullary canal. Limited surgical access during direct anterior THAs increases off-axis forces, potentially contributing to tissue damage. The aim was to characterise impactions during broaching.In a cadaver lab, movement of handle, femur and instrumented mallet was tracked during direct-anterior approach (DAA) and posterior approach (PA). Mallet velocity, broach displacement and input energy were calculated. Following the cadaver lab, different impaction strategies were investigated using bone simulants for a simulated DAA. The effects of reduced mallet velocity inputs and the influence of different impaction locations on the broach handle strike plate were investigated.To seat the broach in cadaveric bone, lower impaction energy (−59%) and number of strikes (−53%) were observed during PA compared to DAA. Suboptimal broach progression was reached in bone simulant at low mallet velocities (3.1 ± 0.3 m/s). Impacting the strike plate's upper part caused larger deflections (p < 0.001) of the Sawbones femur which suggested that higher off axis forces occurred.Awareness of reduced load transmission during DAA broaching using off-axis broach handles, compared to the traditional PA, could help promoting a more efficient and careful impaction strategy in surgeries.

Dissection and ligation of the lateral circumflex femoral artery is not necessary when using the direct anterior approach for total hip arthroplasty.

BACKGROUNDBranches of the lateral circumflex femoral artery (LCFA) stretch across the surgical field during a direct anterior total hip arthroplasty. It is an anatomical marker in direct anterior approach. As an important vessel around the hip joint, this vessel was ligated in most situations. Although ligation of the vascular pedicle of the LCFA is a common, traditional procedure used to decrease bleeding, the ligation of the pedicle of the vessel is tedious and time-consuming.AIMTo explore whether this ligation is truly necessary in a direct anterior approach to total hip arthroplasty.METHODSThis single-center, single-surgeon, prospective study was performed to compare patients’ bleeding undergoing ligation of the branches of the LCFA pedicle (group A) vs those treated with electrocautery from the branches of the LCFA (group B). In both groups, the pedicles were identified in the intermuscular plane between the tensor fasciae lata and the rectus femoris muscles. In group A, the pedicles were ligated with a silk ligature. In group B, the branches coming off the LCFA were controlled with electrocautery. We compared preoperative vs postoperative changes in blood hemoglobin levels, intraoperative blood loss, operative time, rates of transfusion, re-bleeding, and hematoma between the two groups.RESULTSThe reduction of hemoglobin in group A was 20.9 ± 7.0, and in group B it was 21.2 ± 4.9. There was no statistically significant difference between the two groups (P > 0.05). The actual calculated blood loss in group A was 784 ± 125 mL, and in group B it was 722 ± 153 mL. There was a trend in group A having more blood loss (P = 0.078). The estimated blood loss in group A was 344 ± 88 mL, and in group B it was 346 ± 73 mL. There was no statistically significant difference between the two groups (P = 0.883). In addition, there were no significant differences in the rates of postoperative transfusion (10% vs 6.7%, P > 0.05), postoperative hematomas (6.7% vs 13.3%, P > 0.05), or re-bleeding (13.3% vs 20%, P > 0.05) between the two groups.CONCLUSIONLigation of the pedicle of the LCFA has no advantage in preventing or decreasing bleeding during or after a total hip arthroplasty using the direct anterior approach. Ligation of the pedicle of the vessel is a cumbersome, unnecessary procedure and can be replaced by electrocautery control of the branches off this artery that course through the surgical field.

Anterior acetabular retractors and the femoral neurovascular bundle in anterior total hip arthroplasty: a cadaveric study.

The direct anterior approach for primary total hip arthroplasty (THA) has become increasingly popular in recent years. Nerve compression or traction with a retractor is a common cause of nerve injury in this approach. The purpose of this cadaveric study was to evaluate the anatomic relationship of the femoral neurovascular bundle to the anterior acetabular retractor during direct anterior approach THA. Eleven fresh-frozen cadavers underwent a standard direct anterior THA, with placement of an anterior acetabular retractor in the usual fashion between the iliopsoas and acetabulum for visualization during acetabular preparation. Careful dissection of the femoral triangle was performed, and the distances from the anterior retractor tip to the femoral nerve, artery, and vein were recorded and analyzed as mean distance ± standard deviation. In all 11 cadavers, the retractor tip was medial to the femoral nerve. The mean distance from retractor tip to femoral artery and vein was 5.9mm (SD = 5.5, range 0-20) and 12.6mm (SD 0.7, range 0-35), respectively. Surgeons should be aware of the proximity of the neurovascular structures in relation to the anterior acetabular retractor in the direct anterior approach, taking care to avoid perforating the iliopsoas muscle during retractor insertion and limit excessive traction to prevent nerve injury.

Safe Zones for Anterior Acetabular Retractor Placement in Direct Anterior Total Hip Arthroplasty: A Cadaveric Study.

There is paucity of literature evaluating anterior acetabular retractor proximity to the femoral nerve and external iliac vessels during total hip arthroplasty through the direct anterior approach. In this cadaveric study, we evaluated three retractor locations to identify optimal positioning of anterior retractors. A direct anterior approach was performed in 22 hips of 15 cadavers. Anterior acetabular retractors were placed over the anterior acetabular wall in-line with the femoral neck (12-o'clock or middle position). The anterior neurovascular structures were identified through the ilioinguinal approach. Retractors were reinserted at 10-o'clock (right hip; superior) and 2-o'clock (right hip; inferior) locations marked using K-wires. Horizontal and vertical distances from retractor tip positions to neurovascular structures were measured with a digital caliper. Retractor tips moved significantly from lateral to the femoral nerve when placed in the superior position (mean, 2.8 mm) to medial to the femoral nerve in the middle (mean, -2.3 mm) and inferior (mean, -4.8 mm) locations. Retractor tips moved significantly medial toward the external iliac artery when retractors were moved from superior (mean, 15.3 mm) to inferior (mean, 6.6 mm) positions placing the retractor tip closer to the vessels. As retractor placements moved inferior, retractor tips moved medial to neurovascular structures. Inferior retractor positioning placed the femoral nerve and external iliac artery at the risk of injury during the initial retractor placement or adjustment. Retractors should be placed in a relative safe zone superior to the 12-o'clock position to avoid damage to neurovascular structures. IV.

Radiographic factors to predict operation time of direct anterior total hip arthroplasty for dysplastic hips.

This study aimed to identify radiographic factors that could predict surgical difficulty in direct anterior total hip arthroplasty (THA) for dysplastic hips. The clinical records of 160 patients (204 hips) who underwent primary THA for the treatment of developmental dysplasia of the hip were retrospectively investigated. All THAs were performed through a direct anterior approach by a single surgeon. A multiple regression analysis was developed to identify the independent predictor of operation time, including variables such as age, sex, height, body mass index (BMI), the use of bone cement, previous hip surgery, and radiographic references, including the pelvic horizontal to vertical ratio, the extent of proximal and horizontal migration of the femoral head, flatness of the femoral head, and the vertical distance between the tips of the greater trochanter and the femoral head. A multiple regression analysis revealed that as radiographic factors, proximal migration of the femoral head, and lower position of the femoral head related to the greater trochanter were significantly associated with longer operation time. In addition, our results revealed that younger age, male sex, height, high BMI, cement use, and previous hip surgery were also significantly associated with longer operation time. Our findings indicate that proximal migration of the femoral head and high-riding greater trochanter are isolated radiographic predictors of the longer operation time of direct anterior THA for dysplastic hips.

Early Outcomes of Obese Patients Undergoing Total Hip Arthroplasty: Comparison of Anterior to Posterior Approach

BACKGROUND: There has been an increase in total hip arthroplasty in obese patients and surgical complication rates are known to be higher in this population. This retrospective study evaluated complication rates for obese patients undergoing total hip replacement compared to non-obese patients. Additionally, we compared complication rates for direct anterior approach (ATHA) versus posterior approach (PTHA). METHODS: This study was an IRB approved retrospective review of 210 patients undergoing ATHA and 201 patients undergoing PTHA during the same time period by 2 total joint surgeons. Non-obese patients were compared to obese patients using body mass index (BMI) classification. Minor and major complications were reviewed as well as length of stay, disposition, and other short-term outcome measures. RESULTS: The non-obese cohort (BMI < 30) had lower complication rates (2.8% major, 4.4% minor) compared to the obese cohort (8.7% major, 9.9% minor). Major complications by obese class were: Class I 8.6%, Class II 7.1% and Class III 11.5%. The non-obese ATHA cohort had lower complication rates (0.8% major, 5.0% minor) compared to the PTHA cohort (5.0% major, 6.7% minor). Obese patients had 6.3% major and 9.9% minor complication rates in ATHA, compared to 11.1% major and 10.0% minor complication rates in PTHA. Lastly, the evaluation of short-term outcomes showed more favorable results for ATHA for both obese and non-obese patients. CONCLUSION: Obesity was associated with an increased risk of complications and less favorable short-term outcomes following THA. Direct anterior THA was associated with lower complication rates and more favorable short-term outcomes.

Intraoperative evaluation of acetabular cup position during anterior approach total hip arthroplasty: are we accurately interpreting?

Intraoperative radiographic evaluation during total hip arthroplasty (THA) has shown to improve the accuracy of acetabular component placement, however, differences in interpretation based on radiographic technique has not been established. This study aims to determine if differences exist in the interpretation of acetabular component abduction and anteversion between different radiographic projections. 55 consecutive direct anterior THAs in 49 patients were prospectively enrolled. Target anteversion and abduction was defined by the Lewinnek zone. Fluoroscopy was used to direct acetabular component placement intraoperatively. After final cup implantation, fluoroscopic posterior-anterior hip and pelvis images were obtained for analysis. After completion of the procedure, an anterior-posterior plain pelvis radiograph was obtained in the operating room. Acetabulum component abduction and anteversion were postoperatively determined using specialised software on each of the 3 image acquisition methods. Average acetabular cup abduction for intraoperative fluoroscopic posterior-anterior hip (FH), intraoperative fluoroscopic posterior-anterior pelvis (FP), and postoperative, standard, anteroposterior pelvis radiographs (PP) was 40.95° ± 2.87°, 38.87° ± 3.82° and 41.73° ± 2.96° respectively. The fluoroscopic hip and fluoroscopic pelvis tended to underestimate acetabular cup abduction compared to the postoperative pelvis (p < 0.001). Average acetabular cup anteversion for FH, FP, and PP was 19.89° ± 4.87°, 24.38° ± 5.31° and 13.36° ± 3.52° respectively. Both the fluoroscopic hip and fluoroscopic pelvis overestimated anteversion compared to the AP pelvis, with a 6.38° greater mean value measurement for FH (p < 0.001), and an 11° greater mean value measurement for FP (p < 0.001). Fluoroscopic technique and differences between radiographic projections may result in discrepancies in component position interpretation. Our results support the use of the fluoroscopic posterior-anterior hip as the choice fluoroscopic imaging technique.

Hip external rotation and extension angles for exposure and preparation of the proximal femur in direct anterior total hip arthroplasty: A cadaveric study

IntroductionThe direct anterior approach (DAA) to total hip arthroplasty (THA) has a known learning curve, largely due to difficulty achieving exposure and visualization of the acetabulum and proximal femur for joint preparation. There is paucity of information on limb positioning and the degree of angulation at which the limb is positioned for adequate visualization. This study aimed to identify the mean angles of limb positioning necessary for adequate exposure when using two Mueller retractors for femoral preparation using traditional table. Materials & methodsA surgeon performed a DAA THA on 11 cadaveric hemipelves, exposing the femoral canal with two simple, robust Mueller retractors. The degree of external rotation and extension of the hip was measured. ResultsOf the 11, the mean age was 77.6 years and mean BMI was 27.95. The mean external rotation angle was 56.5 ± 13.5°. The mean extension angle was 19.9 ± 6.6°. Discussion & conclusionThe key technical step in this study incorporated a second robust Mueller retractor on the posterior aspect of the greater trochanter, providing maximum leverage to deliver the femur and achieve visibility while reducing angles of limb positioning thereby reducing complications, and ultimately lessening the learning curve.

Prevalence of Postoperative Periprosthetic Femur Fractures Between Two Different Femoral Component Designs Used in Direct Anterior Total Hip Arthroplasty

BackgroundPeriprosthetic femur fractures are a well-documented complication following direct anterior uncemented total hip arthroplasty. The purpose of this study is to compare the prevalence of postoperative periprosthetic femur fractures between 2 different femoral component designs used in direct anterior total hip arthroplasty. MethodsBeginning in February 2015, a single fellowship-trained adult reconstruction surgeon performed 361 consecutive direct anterior total hip replacements using a flat, single-taper, wedged femoral implant. In June 2016, that same surgeon, using the exact same surgical technique and postoperative weight-bearing protocol, began using a dual-taper, hydroxyapatite-coated implant for 789 consecutive hips. The patients were carefully monitored for 3 months after surgery to identify the frequency of periprosthetic femur fractures. A Fisher’s exact test was used to determine if the prevalence of periprosthetic femur fractures differed between the 2 implant designs. ResultsFive of 361 (1.4%) patients sustained proximal femur fractures at an average of 19.6 days postoperatively in the first group, all demonstrating a Vancouver type B2 periprosthetic fracture and requiring femoral revision. No patients (0/789, 0%) in the second cohort sustained a postoperative, periprosthetic fracture (P = .006). ConclusionIn this comparison of 2 consecutive cohorts, the dual-taper, hydroxyapatite-coated implant had a statistically significant lower postoperative periprosthetic fracture rate than a flat, single-taper, wedged design.