Can a simple iPad app improve C-arm based component position in anterior THA?

INTRODUCTION

Correct acetabular component positioning improves hip biomechanics, impingement free range of motion and may lead to a reduced risk of postoperative dislocation. The C-arm is a simple and cost-effective tool for THA in a supine position, however, evaluation of the images can be challenging due to parallax. The current study aimed to investigate whether a software app-based measurement technique can control acetabular component position and leg length in anterior THA.

MATERIALS AND METHODS

Ninety-three patients with end-stage osteoarthritis aged 65.2 ± 9.6 years (range 30-86 years) were included in this prospective study. All patients underwent direct anterior THA using a Hana orthopedic surgery table. C-arm imaging and an iPad software app were used to determine intraoperative acetabular anteversion, inclination and leg length discrepancy. The app provides a measuring tool that is applied to intraoperative c-arm images. The intraoperative measurements were compared to the measurements of standard postoperative AP-pelvis radiographs.

RESULTS

Intraoperative software app-based anteversion measurements averaged 20.5° (range 16.0° to 24.0°) compared to 20.9° (range 14.7° to 25.6°) postoperatively. Mean intraoperative inclination was 40.5° (range 35° to 48°) compared to postoperative 40.7° (range 35° to 49°). Mean intraoperative leg length discrepancy was 0.9 mm (range - 4-5 mm) compared to postoperative 0.6 mm (range - 5-6 mm). A strong Pearson's correlation was observed between the intraoperative and postoperative measurements for anteversion (r = .701; P < .0001), inclination (r = .816; P < .0001) and leg length discrepancy (r = .542; P < .0001).

CONCLUSIONS

The software app used in the current study allowed for a simple and accurate measurement of intraoperative cup position and leg length in direct anterior THA.

Femoral Neck Notching in Dual Mobility Implants: Is This a Reason for Concern?

BACKGROUND

Dual mobility (DM) total hip arthroplasty (THA) implants have been advocated for patients at risk for impingement due to abnormal spinopelvic mobility. Impingement against cobalt-chromium acetabular bearings, however, can result in notching of titanium femoral stems. This study investigated the incidence of femoral stem notching associated with DM implants and sought to identify risk factors.

METHODS

A multicenter retrospective study reviewed 256 modular and 32 monoblock DM components with minimum 1-year clinical and radiographic follow-up, including 112 revisions, 4 conversion THAs, and 172 primary THAs. Radiographs were inspected for evidence of femoral notching and to calculate acetabular inclination and anteversion. Revisions and dislocations were recorded.

RESULTS

Ten cases of femoral notching were discovered (3.5%), all associated with modular cylindrospheric cobalt-chromium DM implants (P = .049). Notches were first observed radiographically at mean 1.3 years after surgery (range 0.5-2.7 years). Notch location was anterior (20%), superior (60%), or posterior (20%) on the prosthetic femoral neck. Notch depth ranged from 1.7% to 20% of the prosthetic neck diameter. Eight cases with notching had lumbar pathology that can affect spinopelvic mobility. None of these notches resulted in stem fracture, at mean 2.7-year follow-up (range 1-7.6 years). There were no dislocations or revisions in patients with notching.

CONCLUSION

Femoral notching was identified in 3.5% of DM cases, slightly surpassing the dislocation rate in a cohort selected for risk of impingement and instability. Although these cases of notching have not resulted in catastrophic failures thus far, further study of clinical sequelae is warranted. Component position, spinopelvic mobility, and implant design may influence risk.

Is Combined Anteversion Equally Affected by Acetabular Cup and Femoral Stem Anteversion?

BACKGROUND

To create a safe zone, an understanding of the combined femoral and acetabular mating during hip motion is required. We investigated the position of the femoral head inside the acetabular liner during simulated hip motion. We hypothesized that cup and stem anteversions do not equally affect hip motion and combined hip anteversion.

METHODS

Hip implant motion was simulated in standing, sitting, sit-to-stand, bending forward, squatting, and pivoting positions using the MATLAB software. A line passing through the center of the stem neck and the center of the prosthetic head exits at the polar axis (PA) of the prosthetic head. When the prosthetic head and liner are parallel, the PA faces the center of the liner (PA position = 0, 0). By simulating hip motion in 1-degree increments, the maximum distance of the PA from the liner center and the direction of its movement were measured (polar coordination system).

RESULTS

The effect of modifying cup and stem anteversion on the direction and distance of the PA's change inside the acetabular liner was different. Stem anteversion influenced the PA position inside the liner more than cup anteversion during sitting, sit-to-stand, squatting, and bending forward (P = .0001). This effect was evident even when comparing stems with different neck angles (P = .0001).

CONCLUSION

Cup anteversion, stem anteversion, and stem neck-shaft angle affected the PA position inside the liner and combined anteversion in different ways. Thus, focusing on cup orientation alone when assessing hip motion during different daily activities is inadequate.

How Does Spinopelvic Mobility and Sagittal Functional Cup Orientation Affect Patient-Reported Outcome 1 Year after THA?-A Prospective Diagnostic Cohort Study

BACKGROUND

This prospective cohort study aimed to characterize how spinopelvic characteristics change post-total hip arthroplasty (THA) and determine how patient-reported outcome measures are associated with 1) individual spinopelvic mobility and 2) functional sagittal cup orientation post-THA.

METHODS

One hundred consecutive patients who received unilateral THAs for end-stage hip osteoarthritis, without spinal pathology were studied. Preoperatively and postoperatively, patients underwent clinical and radiographic evaluations. Patient-reported outcomes were collected using the hip disability and osteoarthritis outcome score - physical function shortform (HOOS-PS). Radiographic parameters measured from standing and relaxed-seated radiographs, included the lumbar lordosis angle, pelvic tilt, pelvic femoral angle and cup orientation in the coronal (inclination/anteversion) and sagittal (anteinclination) planes. Spinopelvic mobility was characterized (ΔPT: "stiff" [<10°], "normal" [10°-30°], and "hypermobile" [>30°]).

RESULTS

Preoperative spinopelvic characteristics were not associated with HOOS-PS. Post-THA, the spinopelvic characteristics changed, with less patients having spinopelvic hypermobility (7%) compared with preop (14%). Postoperatively, patients with spinopelvic hypermobility showed significantly worse HOOS-PS scores (21 ± 17 vs 21 ± 22 vs 41 ± 23; ANOVA P = .037). Sagittal but not coronal cup orientation was associated with postoperative spinopelvic characteristics. Cup anteinclination was less in the patients with postoperative spinopelvic hypermobility (27 ± 7° vs 36 ± 8° vs 36 ± 10°; ANOVA: P = .035).

CONCLUSION

We hypothesize that spinopelvic hypermobility is secondary to impingement and reduced hip flexion; to achieve a seated position, impinging hips require more posterior pelvic tilt. Patients with spinopelvic hypermobility are likely impinging secondary to the low cup anteinclination (sagittal malorientation despite optimum coronal orientation) and thus have lower HOOS-PS compared. Sagittal assessments are thus important to adequately study hip mechanics.

LEVEL OF EVIDENCE

Level II, diagnostic study.

The Effect of a Degenerative Spine and Adverse Pelvic Mobility on Prosthetic Impingement in Patients Undergoing Total Hip Arthroplasty

BACKGROUND

Despite the placement of acetabular components in the traditional "safe-zone", dislocations and all parts of the instability spectrum, including impingement, continue to be an issue. Recent research has established the importance of a degenerative spine and adverse pelvic mobility on functional acetabular orientation. The purpose of this study is to quantify the clinical consequences of a degenerative spine and adverse pelvic mobility on prosthetic impingement in patients undergoing total hip arthroplasty.

METHODS

Between January 2018 and December 2019, a series of 1592 patients undergoing total hip arthroplasty had functional lateral radiographs and a computed tomography scan taken. Two spinal parameters and 2 pelvic mobility parameters were investigated for their association with impingement. Each patient was evaluated for anterior and posterior impingement, at all orientations within a traditional supine safe zone and a patient-specific functional safe zone.

RESULTS

Patients with limited lumbar flexion (stiff spine), higher pelvic incidence-lumbar lordosis mismatch (sagittal imbalance), and more anterior pelvic mobility from stand to flexed-seated, exhibit increased anterior impingement. Patients with larger posterior pelvic mobility from supine-to-stand exhibited increased posterior impingement. Impingement was reduced 3-fold when the target cup orientation was tailored to a patient's functional safe zone rather than a generic target. Six percent of patients showed unavoidable impingement even with an optimized functional cup orientation.

CONCLUSION

Our results support growing evidence that patients with a degenerative spine and adverse pelvic mobility are likely to have unfavorable functional cup orientations, resulting in prosthetic impingement. Preoperative functional radiographic screening is recommended to assess the likelihood of a patient experiencing impingement due to their unique spinopelvic mobility.

Determinants of the primary stability of cementless acetabular cup implants: A 3D finite element study

Primary stability of cementless implants is crucial for the surgical success and long-term stability. However, primary stability is difficult to quantify in vivo and the biomechanical phenomena occurring during the press-fit insertion of an acetabular cup (AC) implant are still poorly understood. The aim of this study is to investigate the influence of the cortical and trabecular bone Young's moduli E_c and E_t, the interference fit IF and the sliding friction coefficient of the bone-implant interface μ on the primary stability of an AC implant. For each parameter combination, the insertion of the AC implant into the hip cavity and consequent pull-out are simulated with a 3D finite element model of a human hemi-pelvis. The primary stability is assessed by determining the polar gap and the maximum pull-out force. The polar gap increases along with all considered parameters. The pull-out force shows a continuous increase with E_c and E_t and a non-linear variation as a function of μ and IF is obtained. For μ > 0.6 and IF > 1.4 mm the primary stability decreases, and a combination of smaller μ and IF lead to a better fixation. Based on the patient's bone stiffness, optimal combinations of μ and IF can be identified. The results are in good qualitative agreement with previous studies and provide a better understanding of the determinants of the AC implant primary stability. They suggest a guideline for the optimal choice of implant surface roughness and IF based on the patient's bone quality.

Well-Placed Acetabular Component Oriented Outside the Safe Zone During Weight-Bearing Daily Activities

Background: A comprehensive and thorough understanding of functional acetabular component orientation is essential for optimizing the clinical outcome after total hip arthroplasty (THA). This study aimed to quantify the functional acetabular anteversion and inclination of unilateral THA patients during walking and static standing and to determine whether the functional acetabular orientation falls within the Lewinnek safe zone. Methods: Seventeen patients with unilateral THA received a CT scan and dual fluoroscopic imaging during level walking and static standing to evaluate in vivo hip kinematics. The pelvic functional coordinate system of the 3D CT-based computer model was defined by the line of gravity and anterior pelvic plane (APP) to measure functional acetabular anteversion and inclination in different postures. The Lewinnek safe zone was used to determine the acetabular malposition during functional activities. Results: The THA side demonstrated an average of 10.1° (± 9.6°, range -7.5° to 29.9°) larger functional anteversion and 16.0° (± 9.2°, range -7.2° to 29.9°) smaller inclination than native hips during level walking. Functional acetabular anteversion in the THA side during level walking and static standing was significantly larger than anatomical measurements (p < 0.05). Acetabular orientation of most well-placed THA components anatomically in the Lewinnek safe zone fell outside the safe zone during more than half of the gait cycle and static standing. Conclusion: The current study revealed that an anatomically well-placed acetabular cup does not guarantee a well-functional orientation during daily activities. The in vivo mechanical performance and loading conditions of the THA component during other weight-bearing activities should be investigated in further studies.

Validation of a Novel Software Measurement Tool for Total Hip Arthroplasty

Background

Preoperative planning and postoperative evaluation of component position in total hip arthroplasty (THA) utilize specialized software that must be able to provide measurements that are both accurate and precise. A new software program for use in THA has recently been developed. We sought to evaluate the accuracy of this new software in comparison with two current, widely used software programs.

Methodology

Postoperative anteroposterior (AP) pelvic radiographs from 135 THA patients were retrospectively reviewed. Reference values for acetabular anteversion, inclination, and leg length were established using validated software programs (TraumaCad^® as the primary reference value [PRV] and OsiriX Lite^TM as the secondary reference value [SRV]). Measurements from the new software program (Intellijoint VIEW^TM) were compared with reference values using Student’s t-test and chi-square test.

Results

For anteversion, mean values for the PRV (27.34° ± 7.27°) and the new software (27.29° ± 7.21°) were not significantly different (p = 0.49). The new software differed from the PRV by a mean of 0.05° ± 0.93°. Similar results were noted for inclination, where the new software differed from the PRV and SRV by -0.13° ± 0.65° and 0.25° ± 1.26°, respectively (mean values: PRV: 43.62° ± 6.02°; SRV: 43.99° ± 6.27°; new software: 43.74° ± 6.17°; p = 0.87), and for leg length, where the new software differed from the PRV and SRV by 0.05 mm ± 0.46 mm and 0.22 mm ± 0.52 mm, respectively (mean values: PRV: 10.61 mm ± 11.60 mm; SRV: 10.77 mm ± 11.70 mm; new software: 10.56 mm ­ ± 11.61 mm; p = 0.98). Measurements were highly correlated across multiple reviewers (intraclass correlation coefficient ≥0.987).

Conclusions

The new software measurement tool is accurate and precise for assessing the acetabular component position and leg length measurements following THA in AP pelvic radiographs compared to currently used image measurement software.

Measurement of operative femoral anteversion during cementless total hip arthroplasty and influencing factors for using neck-adjustable femoral stem

BACKGROUND

Placement of femoral stem in excessive anteversion or retroversion can cause reduced range of motion, prosthetic impingement, and dislocation. The aim of this study was to assess the operative femoral anteversion in patients treated with total hip arthroplasty (THA) and analyze the need of adjusting stem anteversion.

METHODS

We retrospectively included 101 patients (126 hips) who underwent cementless THA with a manual goniometer to determine the femoral anteversion between October 2017 and December 2018. The operative femoral anteversion we measured was recorded during THA. We further divided those hips into three subgroups based on the range of operative femoral anteversion: group 1 (<10°), group 2 (10-30°), and group 3 (>30°) and compared the differences of their demographic data. Univariate and multivariate logistic regression were used to identify the influencing factors for the need of neck-adjustable femoral stem. The clinical and radiographic outcomes were also assessed. Perioperative complications were recorded.

RESULTS

After THA, the Harris hip scores improved from 52.87 ± 15.30 preoperatively to 90.04 ± 3.31 at the last follow-up (p < 0.001). No implant loosening, stem subsidence, and radiolucent lines were observed on radiographs. No severe complications occurred and no components needed revision at the latest follow-up. The mean operative femoral anteversion was 14.21° ± 11.80° (range, -9 to 60°). Patients with femoral anteversion more than 30° were about 10 years younger than others. Femoral anteversion >30° was more common in patients with developmental dysplasia of the hip (DDH). There were totally 14 hips treated with the neck-adjustable femoral stem. From the univariate analysis, we can observe that female sex, diagnosis of DDH (compared with osteonecrosis), and higher operative femoral anteversion and its value >30° (compared with <10°) are associated with higher rates of using the neck-adjustable femoral stem. However, all these factors were no longer considered as independent influencing factors when mixed with other factors.

CONCLUSIONS

This study highlighted the significance of operative femoral anteversion. Identification of abnormal femoral anteversion could assist in adjusting stem anteversion and reduce the risk of dislocation after THA.

Constrained tripolar liner in patients with high risk of dislocation - Analysis of incidence and risk of failure

Introduction

The aim of this study was to determine number and type of failures and revisions after usage of a constrained tripolar acetabular liner in patients with high risk of dislocation. Potential correlations between these failures and the factors included were analyzed.

Materials and methods

In this retrospective study 55 participants in 68 cases were included after treatment with constrained tripolar acetabular liner. Patient specific data as well as surgery and implant specific data were collected. Radiological images were assessed. Furthermore, the gluteal function was analyzed. The parameters were statistically verified with regard to their influence on the failure of the constrained tripolar liner.

Results

This study included 16 cases (in nine participants) of postoperative failure. This results in a survival rate of 76.5% regarding the number of cases after 17 months. The statistical analysis of the different parameters considered that the number of previous surgeries has a significant (p = 0.027) influence on the failure.

Conclusions

This retrospective study shows that treatment with constrained tripolar acetabular liners is a satisfactory method of treatment in cases with a high risk of dislocation. However, in cases with an increasing number of previous surgeries, an increased risk of failure was found. Therefore, in such cases, this type of supply treatment should be treated critically.

Effect of the underlying cadaver data and patient-specific adaptation of the femur and pelvis on the prediction of the hip joint force estimated using static models

The prediction of the hip joint force (HJF) is a fundamental factor for the prevention of edge loading in total hip arthroplasty. Naturally, the loading of the liner of the acetabular component depends on the HJF acting on the artificial joint. In contrast to dynamic musculoskeletal models, static models for HJF prediction do not require motion analysis of the patient. However, patient-specific adaptability and validity of static models have to be scrutinized. In this study, a modular framework for HJF prediction using static models is introduced to compare the results of different cadaver templates that are the basis of most static and dynamic models, and different scaling laws for the patient-specific adaptation with in vivo HJF of ten patients for one-leg stance and level walking. The results revealed the significant effect of the underlying cadaver template used for the prediction of the HJF (p < 0.01). A higher degree of patient-specific scaling of the cadaver template often did not significantly reduce the prediction error. Three static models with the lowest prediction errors were compared to results of dynamic models from literature. The prediction error of the peak HJF of the static models (median absolute errors below 15% body weight in magnitude and below 5° in direction) was similar in magnitude and even smaller in direction compared to dynamic models. The necessary reduction of a load-based target zone for the prevention of edge loading due to the uncertainty of the HJF prediction has to be considered in the preoperative planning. The framework for HJF prediction is openly accessible at https://github.com/RWTHmediTEC/HipJointForceModel.

Iliopsoas Impingement After Direct Anterior Approach Total Hip Arthroplasty: Epidemiology, Risk Factors, and Treatment Options

BACKGROUND

The objective of this study is to evaluate the incidence, natural history, response to treatment, and risk factors for anterior iliopsoas impingement (AIPI) after direct anterior approach (DAA) total hip arthroplasty (THA).

METHODS

Between January 1, 2009 and January 4, 2014, 600 patients (655 hips) who underwent primary DAA THA were retrospectively reviewed. AIPI incidence was calculated. Natural history and response to a stepwise treatment approach was assessed. Radiographic anterior acetabular component overhang was measured. Asymptomatic controls were used to identify risk factors for the development of AIPI.

RESULTS

In total, 518 patients (559 hips) met the inclusion criteria. The incidence of AIPI was 32/559 (5.7%). Symptom resolution occurred in 22/32 (68.8%) patients at final follow-up. Nonoperative management was successful in 15/32 (46.9%) patients. Operative intervention resulted in symptom resolution in 5/8 (62.5%) patients. On univariate analysis, female gender (odds ratio [OR] 2.79), acetabular component to native femoral head diameter ratio above 1.1 (OR 3.85), and any measurable overhang (OR 7.07) significantly raised the risk of AIPI, while increasing native femoral head diameter was protective for AIPI (OR 0.83).

CONCLUSION

AIPI is a cause of groin pain after DAA THA, which often improves with conservative measures. Significant predisposing factors for AIPI include female gender, small native femoral head diameter, increased acetabular component to femoral head diameter ratio, and most notably, any measurable acetabular component overhang.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Evaluation of femoral anteversion, hip rotation, and lateral patellar tilt after total hip arthroplasty using a changeable neck system

In patients with secondary osteoarthritis due to acetabular dysplasia, femoral anteversion has many variations. A changeable neck system is one useful option to adjust the femoral anteversion. Retroverted necks can effectively adjust anatomical anteversion (AA), femoral rotational angle (FRA), and functional anteversion (FA); however, effectiveness of anteverted necks for these adjustments has not been investigated. Moreover, although the lateral patellar tilt after total hip arthroplasty (THA) has been reported to externally rotate, the influence on lateral patellar tilt using a changeable neck system remains unknown. To clarify the effectiveness of anteverted necks in THA, 96 consecutive patients (111 hips) who underwent THA using anatomical short stem with a changeable neck system were retrospectively investigated using pre- and post-operative computed tomography. Patients were divided into the straight (ST) group using straight and 4-mm-high-offset neck (N = 34) and the anteverted (AV) group using 15°-anteverted and 15°-anteverted/3-mm-high-offset neck (N = 34) after age, body mass index, and surgical approach were matched using propensity scores. AA did not change in the ST group, while it increased by 14.0° in the AV group. FRA decreased after surgery in both groups. FA decreased after surgery in the ST group, while it did not change in the AV group. Lateral patella tilt did not significantly change in both groups between pre- and post-operative position. In conclusion, with a changeable neck system, straight and anteverted necks can adjust AA to achieve pre-operative planning while not influencing lateral patellar tilt.

The area method for measuring acetabular cup anteversion: An accurate and autonomous solution

Several radiological methods of measuring anteversion of the acetabular component after total hip arthroplasty have been described, all time-consuming and with varying reproducibility. This study aimed to compare the recently proposed Area method to true cup anteversion as determined by an accelerometer. This study further applied this method programmatically to autonomously determine radiographic cup orientation using two computer programs, then compared these results to hand and accelerometer measurements. 160 anteroposterior pelvis radiographs were taken of a standard Sawbones® pelvis fitted with a total hip arthroplasty system. The acetabular cup was re-oriented between each radiograph, with anteversion ranging from 0° to 90°. An accelerometer was mounted to the cup to measure true cup anteversion. Radiographic anteversion was independently measured via three methods: by hand, linear image processing, and machine learning. Measurements were compared to triaxial accelerometer recordings. Coefficient of determination (R2) was found to be 0.997, 0.991, and 0.989 for hand measurements, the machine learning, and linear image processing, respectively. The machine learning program and hand measurements overestimated anteversion by 0.70° and 0.02° respectively. The program using linear techniques underestimated anteversion by 5.02°. Average runtime was 0.03 and 0.59 s for the machine learning and linear image processing program, respectively. The machine learning program averaged within 1° of cup orientation given a true cup anteversion less than 51°, and within 2° given an anteversion less than 85°. The Area method showed great accuracy and reliability with hand measurements compared to true anteversion. The results of this study support the use of machine learning for accurate, timely, autonomous assessment of cup orientation.

Midterm results of revision total hip arthroplasty for migrated bipolar hemiarthroplasty in patients with hip osteoarthritis using cementless cup with the rim-fit technique

PURPOSE

The results of reamed bipolar hemiarthroplasty (BHA) in patients with hip osteoarthritis (OA) are reported to be unfavorable. Acetabular reaming for sufficient bony coverage caused bipolar head migration into the superomedial direction, and most patients required revision surgeries. Several methods are applicable to treat decreased bone stock. This study aimed to investigate the midterm results of revision surgeries using the cementless cup with the rim-fit technique.

METHODS

Between 1996 and 2014, acetabular revision surgeries using the cementless cup with the rim-fit technique were performed in 86 hips (74 patients). We evaluated radiographic outcomes, including positional change of the rotation center of the artificial femoral head, presence of implant loosening, and filling of the initial gap. We also evaluated clinical outcomes, including the Harris hip score (HHS), and postoperative complications.

RESULTS

The average positional changes from BHA to prerevision surgeries were 8.0 mm superiorly and 4.1 mm medially. The average changes from prerevision to postrevision surgeries were 3.7 mm inferiorly and 2.4 mm laterally. No implant loosening was found in all cases; the initial gap between the acetabular host bone and the acetabular cup was filled in 53 (93%) among 57 hips. The average HHS improved from 65.9 before revision surgeries to 83.8 in the latest follow-up. Dislocation and postoperative periprosthetic fracture occurred in two and five hips, respectively; no cases required rerevision surgeries.

CONCLUSION

There were favorable midterm results of the revision total hip arthroplasty for migrated BHA in patients with hip OA using cementless cup with the rim-fit technique.

Comparison of Cup Setting Angle Accuracy between Computed Tomography-Based and Computed Tomography-Free Navigation in the Same Patients with Crowe's Classification I or II Hip Dysplasia

Backgroud

In total hip arthroplasty, the cup setting angle may affect the postoperative results. In recent years, both computed tomography-based navigation and computed tomography-free (imageless) navigation have been reported to produce high accuracy in cup installation; however, no direct comparison between these two methods has been performed. The present study aimed to directly compare the cup installation angle accuracy between computed tomography-based navigation and computed tomography-free navigation in patients with Crowe's classification stage I or II dysplastic osteoarthritis and to examine the factors affecting the cup installation accuracy.

Methods

Using both navigation systems for the same technique, primary total hip arthroplasty was performed by the same surgeon in 36 patients. A cup was installed using computed tomography-based navigation, and the installed cup was measured again using computed tomography-free navigation. We compared the error between the target angle and the intraoperative installation angle for each navigation method by performing statistical analyses.

Results

For computed tomography-based navigation, errors in the inclination and the anteversion angles compared to the target angle were 3.14° ± 1.55° and 1.47° ± 0.99°, respectively. For computed tomography-free navigation, the inclination and anteversion angle errors were significantly larger, i.e., 6.84° ± 4.78° and 5.43° ± 5.22°, respectively (p < 0.01). The inclination and anteversion angles of computed tomography-free navigation were correlated, and there were no significant factors influencing the error.

Conclusions

Computed tomography-based navigation is more accurate for cup installation than computed tomography-free navigation. When using computed tomography-free navigation, it is necessary to add technical schemes before and during surgery to improve the cup installation accuracy.

Accuracy of cup position following robot-assisted total hip arthroplasty may be associated with surgical approach and pelvic tilt

This study aimed to investigate the accuracy of cup placement and determine the predictive risk factors for inaccurate cup positioning in robot-assisted total hip arthroplasty (THA). We retrospectively analyzed 115 patients who underwent robot-assisted THA between August 2018 and November 2019. Acetabular cup alignment and three-dimensional (3D) position were measured using pre- or postoperative computed tomography (CT) data. Absolute differences in cup inclination, anteversion, and 3D position were assessed, and their relation to preoperative factors was evaluated. The average measurement of the absolute differences was 1.8° ± 2.0° (inclination) and 1.9° ± 2.3° (anteversion). The average absolute difference in the 3D cup position was 1.1 ± 1.2 mm (coronal plane) and 0.9 ± 1.0 mm (axial plane). Multivariate analysis revealed that a posterior pelvic tilt [odds ratio (OR, 1.1; 95% confidence interval (CI), 1.00–1.23] and anterior surgical approach (OR, 5.1; 95% CI, 1.69–15.38) were predictive factors for inaccurate cup positioning with robot-assisted THA. This is the first study to demonstrate the predictive risk factors (posterior pelvic tilt and anterior surgical approach) for inaccurate cup position in robot-assisted THA.

[What are the benefits of patient-specific reconstruction in total hip replacement?]

BACKGROUND

The success of primary total hip replacement (THR) is predominately determined by the primary stability of the implant and the restoration of the patient-specific joint biomechanics. The three-dimensional (patho-) anatomy, size, geometry, and shape of the acetabulum and proximal femur is highly variable in patients with advanced hip osteoarthritis. Accurate preoperative planning is an essential prerequisite for all replacement procedures.

CURRENT SITUATION

Current data demonstrates clinical advantages for patient-specific reconstruction of functional joint geometry via surrogate parameters (offset and leg length). Frequently cited "target zones" for the positioning and orientation of the cup are increasingly in the focus of scientific discussion, as individually adjusted target zones for implant positioning allow for a potential reduction of impingement risk. Patients with spinal fusions or pathologic spinopelvic alignment require that particular attention be paid to patient-specific preoperative preparation, the surgical technique, and implant selection in order to reduce the risk of postoperative instability.

No Clinically Important Differences in Thigh Pain or Bone Loss Between Short Stems and Conventional-length Stems in THA: A Randomized Clinical Trial

BACKGROUND

Short-length stems were developed to reduce bone loss of the proximal femur and potentially decrease the incidence of thigh pain after cementless THA. However, it remains unknown whether short stems indeed reduce bone loss or the frequency of thigh pain.

QUESTIONS/PURPOSES

Is there a difference between short- and standard-length stems in terms of: (1) the frequency or severity of thigh pain, (2) modified Harris hip scores, (3) implant loosening, or (4) bone mineral density as measured by dual-energy x-ray absorptiometry?

METHODS

Between March 2013 and January 2014, three surgeons performed 205 primary THAs. To be eligible, patients needed to be at least 20 years of age, have not undergone previous history of hip surgery, and have no metabolic bone disease. A total of 100 patients were randomized to receive THA either with a short stem (n = 56) or with a standard-length stem (n = 44). Both stems were proximally coated, tapered, cementless stems. Compared with standard stems, short stems typically were 30- to 35-mm shorter. A total of 73% (41 of 56) and 77% (34 of 44) of those groups, respectively, were accounted for at a minimum of 5 years and were analyzed. The presence of thigh pain during activity was evaluated using a 10-point VAS, and the modified Harris hip score was calculated by research assistants who were blinded to the treatment groups. Plain radiographs were taken at 6 weeks, 6 months, and 12 months postoperatively, and every 1 year thereafter; loosening was defined as subsidence > 3 mm or a position change > 3° on serial radiographs. Radiological assessment was performed by two researchers who did not participate in the surgery and follow-up evaluations. Bone mineral density of the proximal femur was measured using dual-energy x-ray absorptiometry at 4 days, 1 year, 2 years, and 5 years postoperatively. The primary endpoint of our study was the incidence of thigh pain during 5-year follow-up. Our study was powered at 80% to detect a 10% difference in the proportion of patients reporting thigh pain at the level of 0.05.

RESULTS

With the numbers available, we found no difference between the groups in the proportion of patients with thigh pain; 16% (9 of 56) of patients in the short-stem group and 14% (6 of 44) of patients in the standard-stem group experienced thigh pain during the follow-up period (p = 0.79). In all patients, the pain was mild or moderate (VAS score of 4 or 6 points). Among the 15 available patients who reported thigh pain, there was no difference between the implant groups in mean severity of thigh pain (4.3 ± 0.8 versus 4.2 ± 0.7; p = 0.78). There were no between-group differences in the short versus standard-length stem groups in terms of mean modified Harris hip score by 5 years after surgery (89 ± 13 versus 95 ± 7 points; p = 0.06). No implant was loose and no hip underwent revision in either group. Patients in the short-stem group showed a slightly smaller decrease in bone mineral density in Gruen Zones 2, 3, and 5 than those in the standard-stem group did; the magnitude of the difference seems unlikely to be clinically important.

CONCLUSION

We found no clinically important differences (and few differences overall) between short and standard-length THA stems 5 years after surgery in a randomized trial. Consequently, we recommend that clinicians use standard-length stems in general practice because standard-length stems have a much longer published track record in other studies, and short stems can expose patients to the uncertainty associated with novelty, without any apparent offsetting benefit.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Changes of acetabular anteversion according to pelvic tilt on sagittal plane under various acetabular inclinations

Improper functional orientation of the acetabular cup can result in improper positions when dynamic pelvic positions are not considered. The purpose of this study was to evaluate changes on acetabular anteversion according to pelvic tilt under various acetabular inclinations. Two artificial pelvic models were selected for this study. Acetabular inclinations on the coronal plane were 25°, 32°, 50°, and 60°. Acetabular anteversion of all components were 15°. Changes of anteversion according to pelvic tilt were measured at angles of 0°, 10°, 20°, 30°, and 40°. Computer Navigation, PolyWare 3D pro, CT, and plain radiography were used to measure each angle. The anatomical anteversions against pelvic tilt were calculated using the following formulae: anatomical anteversion (°) = -14.48Χ + 90.18 (inclination angle 25°); anatomical anteversion (°) = -12.26Χ + 80.10 (inclination angle 32°); anatomical anteversion (°) = -7.468Χ + 61.13 (inclination angle 50°); and anatomical anteversion (°) = -5.328Χ + 44.84 (inclination angle 60°) (Χ: pelvic tilt angle). Radiographic anteversion against pelvic tilt were calculated using the following formulae: radiographic anteversion (°) = -9.50Χ + 57.09 (inclination angle 25°); radiographic anteversion (°) = -8.577Χ + 50.89 (inclination angle 32°); radiographic anteversion (°) = -6.794Χ + 45.73 (inclination angle 50°); radiographic anteversion (°) = -5.226Χ + 33.08 (inclination angle 60°). In conclusion, changes in anteversion according to pelvic tilt were lesser at higher degrees of acetabular inclination.

Early postoperative clinical recovery of robotic arm-assisted vs. image-based navigated Total hip Arthroplasty

BACKGROUND

This study compared the early clinical recovery of total hip arthroplasty (THA) using computer navigation systems (nTHA) and robotic arm-assisted THA (rTHA).

METHODS

Thirty prospective subjects who underwent rTHA were clinically compared to 30 subjects who underwent nTHA. Clinical data (surgical time, intraoperative blood loss, pain severity, number of days to independent walking, and Harris Hip Score (HHS) at discharge), and radiographic parameters (inclination and anteversion angles) were statistically compared between the two groups.

RESULTS

Follow-up times were 24.3 ± 6.0 and 27.0 ± 7.0 days in the rTHA and nTHA groups, respectively. The surgical time (135.1 ± 13.9 min vs. 146.2 ± 12.8 min, p = 0.002), number of days to independent walking (7.2 ± 2.0 vs. 11.5 ± 3.0 days, p < 0.001), and postoperative pain using a numeric rating scale on postoperative days 7, 10,, and 14 (1.4 ± 0.9 vs. 2.2 ± 1.2, p = 0.005; 1.0 ± 0.8 vs. 1.8 ± 1.1, p = 0.002; 0.3 ± 0.5 vs. 1.1 ± 0.9, p < 0.001; respectively) were significantly reduced in the rTHA group compared to the nTHA group. The rTHA group showed a significantly higher postoperative HHS compared to the nTHA group (85.3 ± .3.2 vs. 81.0 ± 8.5, p = 0.014). No statistically significant difference was observed in radiographic parameters between the groups; however, the incidence of intraoperative target angle changes was significantly lower in the rTHA group than in the nTHA group (0/30 subjects [0%] vs. 11/30 subjects [36.7%], p < 0.001).

CONCLUSION

The surgical time, postoperative pain, and number of days to independent walking were significantly shorter, and the HHS at discharge was significantly higher in the rTHA group than in the nTHA group. Thus, compared to the nTHA group, the rTHA group showed improved early clinical recovery.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Mid-Term Outcomes of Cementless Total Hip Arthroplasty in Adult Patients with Childhood Hip Infection

BACKGROUND Patients with hip joint infections in childhood often have many aftereffects of different degrees, regardless of the kind of treatment or natural course. Total hip arthroplasty is currently the most effective treatment for sequelae of childhood hip septic or tuberculous infection. This is a mid-term follow-up study of treatment results of patients who had undergone total hip arthroplasty (THA) with cementless prostheses. MATERIAL AND METHODS We retrospectively analyzed and followed 45 patients (45 hips) who underwent THA with cementless prostheses between 2010 and 2017. There were 45 patients, including 17 men and 28 women. The average age of the patients was 46 years (range, 18-67 years). All hip infections occurred in early childhood or adolescence, and the mean interval between initial infection and THA was 38.2 years (range, 15-60 years). The mean follow-up was 6.1 years (range, 2.7-9.5 years). RESULTS Two patients underwent revision surgery because of loosening of the prosthesis, and 1 patient underwent revision surgery because of a new infection with no relationship with childhood infection during the follow-up. The average Harris hip scores significantly increased from 43.1 to 86.4 (P<0.01), and the average visual analog scale significantly increased from 4.6 to 1.7 (P<0.01). The hip dysfunction and osteoarthritis outcome scores were also significantly changed (P<0.01) at the final follow-up. There were 2 cases of transient sciatic nerve palsy and intraoperative periprosthetic fractures in 3 cases. During follow-up, single revision was performed after 6 years of primary arthroplasty because of aseptic loosening in 2 cases and prosthesis infection in 1 case, which was not related to childhood pathogens. CONCLUSIONS THA for patients with sequelae of hip joint infection has a satisfactory effect that can effectively relieve joint pain and improve hip function. The recurrence rate of infection after either pyogenic infection or tuberculous is very low. The mid-term outcomes of THA in this setting were satisfactory, with high prosthesis survivorship and hip function scores.

Arthroplasty of the Knee: Current Techniques for Implant Alignment

When a total knee arthroplasty (TKA) is implanted using the traditional mechanical alignment technique, this typically results in a straight leg, independently of pre-operative or even pre-arthrotic varus or valgus alignment. With mechanical alignment, we distinguish between 2 different alignment techniques: ligament balancing and bony referencing according to bony skeletal landmarks. In ligament balanced technique beside the straight mechanical axis, the prosthesis is implanted at 90° to the latter. The rotational alignment of the femur is set according to the ligament tension. In the skeletal referenced technique, the rotation of the femur is also set according to bony skeletal landmarks. As a variation of this technique, the prosthesis can be implanted with anatomical alignment. In this technique, the medial slope of the joint line of 3° in the frontal plane is respected during the implantation of TKA. Both techniques result in comparable long-term results with survival rates of almost 80% after 25 years. On the other hand, 15 – 20% of TKA patients report dissatisfaction with their clinical result. For more than 10 years now, the kinematic TKA alignment concept has been developed with the goal to achieve implantation that is adapted to the individual anatomy of the patient. The advocates of this technique expect better function of TKA. This strategy aims to reconstruct the pre-arthrotic anatomy of a given patient while preserving the existing joint line and the mechanical axis without performing ligamentary release. Studies have shown that the function of the prothesis is at least that good as in the conventional techniques. Long-term results are still sparse, but initial studies show that TKA implanted using the kinematic alignment technique exhibit comparable 10-year-survival rates to those implanted using the traditional mechanical alignment technique. Future studies need to show the limitations of this new technique and to identify patients who will or will not significantly benefit from this technique.

Supercapsular percutaneously-assisted total hip (SuperPath) versus mini-incision posterolateral total hip arthroplasty for hip osteoarthritis: a prospective randomized controlled trial

Background

Supercapsular percutaneously-assisted total hip (SuperPath) arthroplasty has been proposed to be minimally invasive and tissue sparing, with possible superior postoperative outcomes compared with conventional approaches for total hip arthroplasty (THA). However, previous studies have underlined the shortcomings of conventional THA approaches, including higher dislocation, more blood loss, longer incisions, more tissue damage, and delayed postoperative rehabilitation. In the present study, we compared the short-term outcomes of unilateral THA with those of SuperPath and the mini-incision posterolateral approach (PLA) for hip osteoarthritis (OA).

Methods

Patients with unilateral hip OA were prospectively recruited and underwent either SuperPath (SuperPath group) or mini-incision PLA THA (PLA group). Perioperative status [operative time, incision length, intraoperative blood loss, soft tissue damage, and length of hospital stay (LOS)], and postoperative function outcomes, including range of motion (ROM), pain visual analog scale (VAS), and Harris Hip Score (HHS), were evaluated and compared between the groups at scheduled time points within 12 months postoperatively.

Results

Compared with the PLA group, the SuperPath group yielded a significantly shorter incision length (7.83 vs. 12.45 cm, P<0.001), longer operative time (102.72 vs. 66.22 min, P<0.001), more blood loss (1,007.38 vs. 844.55 mL, P=0.005), and more soft tissue damage (creatine kinase: 1,056.05 vs. 821.50 U/L, P=0.006) on postoperative day 3. The SuperPath group also showed deficient acetabular cup positioning (abduction angle: 36.94° vs. 42.66°, P=0.004) and a greater decrease in ROM (flexion: 107.66° vs. 114.44°, P=0.004; 109.83° vs. 116.11°, P=0.002; 111.66° vs. 118.88°, P<0.001) on postoperative days 1, 3, and 14, as well as severe early-term pain symptoms (pain VAS on postoperative day 3: 7.05 vs. 6.55, P=0.041). However, the LOS, C-reactive protein levels, erythrocyte sedimentation rate (within 2 weeks postoperatively), and HHS were comparable between the groups during the 12 months postoperatively.

Conclusions

SuperPath may be a promising, minimally invasive technique for the treatment of OA in the future. Further investigation is necessary to evidence the possible superiority of SuperPath over other conventional mini-incision THA approaches.

Cementless total hip arthroplasty with delta-on-delta ceramic bearing in patients younger than 30 years

BACKGROUND

Despite improvements in the mechanical properties of alumina ceramics, the outcome of total hip arthroplasty (THA) with contemporary ceramic bearings in young patients remains a matter of concern. We evaluated the results of cementless THA with the use of the delta ceramic bearing, and determined the prevalence of osteolysis, squeaking, and ceramic fracture in patients aged < 30 years at mid-term.

METHODS

From March 2008 to January 2012, 76 consecutive patients (91 hips), younger than 30 years, underwent cementless THA with Delta ceramic bearings. In each follow-up, the clinical evaluation including noise and radiological evaluations were recorded.

RESULTS

Among them, 72 patients (86 THAs) were followed-up for a minimum of 5 years (mean 70.8; 60-95.9 months). There were 44 men (47 hips) and 28 women (39 hips). The mean age at the time of the index arthroplasty was 25.9 (16-30) years and the mean preoperative Harris Hip Score (HHS) was 59.4 (23-79) points. HHS improved to 96.3 (64-100) points at the final follow-up evaluation. 8 hips (9.3%) exhibited grinding or squeaking. No hip had aseptic loosening and no hip was revised. No osteolysis was detected around any acetabular or femoral components.

CONCLUSIONS

Our results suggest that cementless THA with the use of Delta ceramic bearing provides satisfactory results without osteolysis or ceramic fracture in patients aged <30 years at a mid-term follow-up.Clinical Trials.gov Protocol Registration System (trial no. NCT01838096).

Anterior pelvic plane tilt poorly estimates the sagittal body alignment due to internal rotation of innominate bone

This study investigated the influence of the rotation of innominate bone on anterior pelvic plane (APP) tilt, the angle formed by the APP, and coronal plane of the body to determine whether the provision of proper information about the sagittal balance of the body by the value of the APP tilt (APPT). In total, 244 patients (171 females, 73 males) who were candidates for total hip or knee arthroplasty, periacetabular osteotomy, or shelf arthroplasty were included. The rotational angle of the innominate bone was quantified using computed tomography images at the level of the anterior superior, and anterior inferior iliac spine, and ischiopubic portion. Clustering analysis was performed to identify subtypes of innominate bone rotation. High, intermediate, and low internal rotational alignment groups were identified in females, characterized by rotational angles. Males were treated as one group, and no intergroup differences were observed in sacral slope (SS) and pelvic incidence. However, intergroup differences in APPT were found, indicating a variation in APPT irrespective of sagittal body balance. A negligible relationship between SS and APPT was observed in the high-internal-rotation group, intermediate-internal-rotation group, and male group, whereas a moderate correlation found in the low-internal-rotation group (r = .59). The results could suggest surgeons that the value of the APPT provides no information on the sagittal balance; therefore, it may be ignored for acetabular component positioning during preoperative planning for total hip arthroplasty.

Targeting the safe zones for cup position without fluoroscopic guidance in total hip arthroplasty: does the surgical approach affect the outcomes?

BACKGROUND

Proper acetabular cup positioning is crucial for achieving implant longevity and stability in total hip arthroplasty (THA). One of the elements that may affect the accuracy and precision of the positioning of the cup is the type of surgical approach used. This study compares the accuracy and the precision of conventional free-hand acetabular cup positioning relative to different "safe zones" in two groups of patients operated with THA using two different surgical approach.

METHODS

Retrospective radiological comparative matched-pair controlled study of two groups of patients operated with primary THA: the first group was operated in supine decubitus with a mini-invasive direct anterior approach (DA group), the second group was operated in lateral decubitus with a conventional posterolateral approach (PL group). Cup inclination and anteversion were assessed using the digital planning software TraumaCad. Cup position in the two groups were compared in terms of accuracy and precision.

RESULTS

Forty four patients were enrolled for each group. The DA group showed a less inclined and less anteverted cup compared to the PL group (respectively 38.5 ± 5.2 vs. 49.6 ± 5.6 and 16.2 ± 3.6 vs. 22.9 ± 6.4; p < 0.01). The DA group showed a significantly higher percentage of cups within the "safe zone" in 4 out of 6 reference zones and a significantly lower variance in anteversion (12.96 vs. 40.96, p < .01). There was no difference in the variance for inclination.

CONCLUSIONS

Our study found greater accuracy and precision in the positioning of the cup when surgery was performed through a direct anterior approach compared to the posterolateral approach due to the supine position of the patient which allows greater stability of the pelvis during surgery and makes it easier to target the desired angular references for cup positioning.

Use of traction table did not increase complications in total hip arthroplasty through direct anterior approach performed by novice surgeon

PURPOSE

The purpose of this study was to investigate the surgical outcomes of total hip arthroplasty (THA) through direct anterior approach (DAA) performed by beginners by comparing the outcomes after the introduction of DAA-THA between using a normal operating table and a traction table.

METHODS

The total subjects were 200 patients, there were 120 cases from the introduction of three surgeons using a normal table and 80 cases from two surgeons using a traction table. The surgical procedure was standardized, and a surgeon skilled in DAA entered the operating room and instructed the novice surgeons of DAA in all cases.

RESULTS

The mean operative time was no significant difference between the two groups (p = 0.093). The difference in slope of the operative time was no significant difference between the two groups (p value = 0.089). The mean fluoroscopy time and the mean blood loss were significant difference between the two groups (p < 0.05). The difference in slope of the fluoroscopy time and blood loss were significant difference between the two groups (p < 0.05). There were no intraoperative complications and no reoperations for any reason.

CONCLUSIONS

At the facility with a surgeon skilled in DAA, the use of a traction table in DAA did not increase the complication rate compared with the use of a normal operating table when the exclusion criteria for DAA were set and surgery was performed using intraoperative fluoroscopy under supervision by a skilled surgeon.

3D Printed Guides and Preoperative Planning for Uncemented Stem Anteversion Reconstruction during Hip Arthroplasty: A Pilot Study

Objective

To investigate if 3D printed guides and preoperative planning can accurately control femoral stem anteversion.

Methods

A prospective comparative study was carried out from 2018 to 2020, including 53 patients who underwent hip arthroplasty for femoral neck fracture. The target rotation center of the femoral head is determined by three-dimensional planning. In group A, planning was made by 2D templates. In group B, preoperative 3D planning and 3D printed osteotomy/positioning guides were performed. After the operation, 3D model registration was performed to calculate the accuracy of anteversion restoration.

Results

We screened 60 patients and randomized a total of 53 to 2 parallel study arms: 30 patients to the group A (traditional operation) and 23 patients to the group B (3D preoperative planning and 3D printed guide). There were no significant differences in demographic or perioperative data between study groups. The restoration accuracy of group A was 5.42° ± 3.65° and of group B was 2.32° ± 1.89°. The number and rate of abnormal cases was 15 (50%) and 2 (8.7%), respectively. Significant statistical differences were found in angle change, restoration accuracy, and number of abnormal cases.

Conclusion

Three-dimensional preoperative planning and 3D printed guides can improve the accuracy of the restoration of femoral anteversion during hip arthroplasty.

Evaluation of Dislocation Risk Factors With Total Hip Arthroplasty in Developmental Hip Dysplasia Patients: A Multivariate Analysis

BACKGROUND

This study aimed to investigate the risk factors for dislocation in patients diagnosed with developmental dysplasia of the hip (DDH) who underwent total hip arthroplasty.

METHODS

We retrospectively reviewed 40 patients who developed dislocation and compared them with 400 patients in the control group without hip instability. Patients-, surgery-, and implant-related factors were investigated. Risk factors were evaluated using multivariate logistic regression.

RESULTS

The mean follow-up period was 32.3 months. The mean time to dislocation was 4.4 months. There were 7 men (17.5%) and 33 women (82.5%) in the dislocation group and 83 men (20.7%) and 317 women (79.3%) in the control group (P = .627). Diabetes mellitus (DM; P = .032) and history of previous hip surgery for DDH were associated with dislocation (P < .001). The subtrochanteric shortening osteotomy (P = .001), acetabular inclination (P = .037), acetabular anteversion (P < .001), femoral head size (P < .001), and postoperative infection (P = .003) were associated with dislocation. Major predictors of hip dislocation after total hip arthroplasty in patients with DDH were previous hip surgery (odds ratio [OR], 6.76; 95% confidence interval [CI], 1.86-24.6; P = .004), high hip center (OR, 2.90; 95% CI, 1.31-6.38; P = .008), DM (OR, 2.68; 95% CI, 1.06-6.80; P = .037), and acetabular inclination (OR, 2.62; 95% CI, 1.09-6.26; P = .03).

CONCLUSION

Patients with DM and previous hip surgery should be informed about increased dislocation rates. Using a larger head diameter and restoration of the true hip rotation center are essential to prevent hip dislocation in these patients. Furthermore, accurate positioning of the acetabular inclination and anteversion are also important.

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

BACKGROUND

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

PATIENTS AND METHODS

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

RESULTS

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

DISCUSSION

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

LEVEL OF EVIDENCE

III.

Does Structured Postgraduate Training Affect the Learning Curve in Direct Anterior Total Hip Arthroplasty? A Single Surgeon's First 200 Cases

Background

The direct anterior approach (DAA) used for primary total hip arthroplasty has been shown to improve early postoperative outcomes, but prior studies have identified a marked learning curve for surgeons transitioning to this approach. However, these studies do not capture surgeons with postgraduate fellowship training in DAA. Therefore, the purpose of this study was to evaluate the learning curve by comparing perioperative outcomes for the first 100 to latter 100 cases and first 50 to final 50 cases.

Methods

The first 200 consecutive primary total hip arthroplasties performed by a single surgeon were prospectively followed up for up to 2 years postoperatively. Data on demographic and perioperative factors, 90-day readmissions, and short- and long-term complications were collected. Radiographic outcomes included acetabular cup anteversion and abduction measurements. Logistic regressions were used to calculate odds ratios and confidence intervals for surgical time greater than 2 hours.

Results

The first 100 and second 100 cases had significant differences in operative times (118.1 vs 110.4 minutes, P = .009), acetabular abduction (38.3 vs 35.5 degrees, P = .001) and anteversion (13.5 vs 15.1 degrees, P = .009), and incidence of neuropraxia (41 vs 9%, P < .001). Estimated blood loss, transfusions, discharge disposition, length of stay, readmission, and other complications had no statistical significance between the first and second 100 cases. The first 50 cases had higher odds of surgical time greater than 2 hours (odds ratio = 5.2, 95% confidence interval = 1.84-14.75, P = .002) than the final 50 cases.

Conclusions

When compared with the existing literature, incorporation of DAA into fellowship training can lead to reduction in fractures and reoperation rates.

Impact of Acetabular Implant Design on Aseptic Failure in Total Hip Arthroplasty

Background

Failure of cementless acetabular osseointegration is rare in total hip arthroplasty. Nevertheless, new fixation surfaces continue to be introduced. Novel implants may lack large diameter, constrained bearings, or dual mobility (DM) bearings to address instability. We compared clinical and radiographic outcomes for acetabular components with differing fixation surfaces and bearing options, focusing on the relationship between fixation surface and osseointegration and the relationship between bearing options and dislocation rate.

Methods

We retrospectively reviewed 463 total hip arthroplasties implanted with 3 different acetabular components between 2012 and 2016. Records were reviewed for demographics, clinical scores, and complications. Radiographs were examined for evidence of acetabular osteointegration. Analysis of variance and chi-square tests were used to compare cohorts.

Results

All cohorts had 100% survivorship free of acetabular fixation failure with no differences in clinical scores. Dislocation occurred in 1.3% of cases (n = 6). Analysis of the “transition” sizes, for which brand determined the maximum bearing diameter, revealed a significantly higher dislocation rate (3/50, 6%) in implants with limited bearing options. All 4 revisions for recurrent dislocation involved well-positioned components that did not accept large diameter, constrained bearings, or DM bearings, resulting in 3 shell revisions to expand bearing options. Femoral revisions were associated with dislocation risk but did not vary between cohorts.

Conclusion

Dislocation was the primary mechanical cause for acetabular revision, while acetabular fixation failure was not encountered. We caution against selecting “new and improved” acetabular components without options for large diameter, constrained bearings, or DM bearings, even when enabling technology makes component positioning reliable.

Smartphone-assisted technique in total hip arthroplasty can improve the precision of acetabular cup placement: a randomised controlled trial

BACKGROUND

Malposition of the acetabular component mainly results from intraoperative pelvic motion and manual errors during cup placement. We investigated the outcomes of a device that uses a level indicator application of a smartphone to function as a pelvic tilt goniometer to assess intraoperative motion. The cup positions outside Lewinnek's safe zone were compared between the smartphone-assisted technique and the conventional method that uses a mechanical alignment guide.

METHODS

A randomised controlled trial was conducted among 64 patients receiving primary cementless total hip arthroplasties (THAs) via a posterolateral approach from June 2015 to February 2017. Acetabular components were implanted either by conventional technique (n = 32) or using smartphone technique (n = 32). Inclination and anteversion angles were measured in supine pelvic radiographs.

RESULTS

The inclination angle in the smartphone group was not significantly different from the conventional group (41.2° ± 3.9° vs. 40.3° ± 7.9°, p = 0.567). The anteversion angle was also similar (19.3 ± 3.8° vs 19.1° ± 5.9°, p = 0.856). However, the standard deviation of the angle in the smartphone group was significantly lower for inclination (p < 0.001) and anteversion (p = 0.016). There were 3 outliers (9.4%) in the smartphone group, but 13 (40.6%) in the conventional group (p = 0.008). The risk ratio was 0.23 (95% CI, 0.07-0.73). The risk difference was -0.31 (95% CI, -0.51- -0.11).

CONCLUSION

The smartphone-assisted technique in THA improves the precision of cup placement and decreases the percentage of safe zone outliers.Thai Clinical Trials Registry (ID: TCTR20151123002).

Trans-lateral decubitus radiograph of the hip: A new view to measure the anteversion of the femoral stem

BACKGROUND

Malposition of the femoral stem is a risk factor for dislocation after total hip arthroplasty (THA). Currently, two radiological methods are available for the measurement of stem anteversion. However, one method is not applicable in patients with a stiff hip, and the other one cannot differentiate the anteversion and retroversion of the stem. Therefore, we developed a method to measure the stem anteversion and assessed its reliability as well as validity.

METHODS

Trans-lateral decubitus view of the proximal femur was taken with the patient in lateral decubitus position, the hip in extension and the knee in 90° flexion. Hip anteroposterior (AP) view, trans-lateral decubitus view and CT scan of the hip were taken in 36 patients, who underwent THA. Their mean age was 59.8 (27-84) years and the mean body mass index was 25.2 (18.8-30.9) kg/m2. The stem neck-femoral shaft angle was measured on hip AP view and the trans-lateral decubitus view. Then, the stem anteversion was calculated using the Ogata-Goldsand formula. We assessed the intra- and inter-observer reliabilities and evaluated the validity by comparing with the measurements on CT scan.

RESULTS

The intra- and inter-observer reliabilities were 0.934 and 0.935, respectively. The calculated stem anteversion (23.72°±8.17°) correlated well with the stem anteversion on CT scan (23.91°±10.25°), especially when the radiological anteversion was <30° (correlation coefficient = 0.729, p = 0.001).

CONCLUSION

We developed a reliable and valid method to measure stem anteversion using hip AP view and trans-lateral decubitus view of the femur. This method can replace conventional radiological methods.

Conventional cementless total hip arthroplasty in patients with dwarfism with height less than 140 cm and minimum 10-year follow up: A clinical study

BACKGROUND

Orthopedic complications can cause issues and severe disability in patients with dwarfism. Thus, these individuals frequently undergo total hip arthroplasty to mitigate decline in daily functioning. Although studies have reported on the difficulties of orthopedic surgery in patients with dwarfism, many do not clearly define dwarfism and have a short follow-up period. We aimed to retrospectively investigate the clinical and radiographic results of total hip arthroplasty for patients with dwarfism.

METHODS

A total of 68 hips of 49 patients with height <140 cm and at least 10-year follow-up periods were enrolled. All patients had conventional cementless implants. All hips were evaluated using the Japanese Orthopaedic Association hip score.

RESULTS

The main hip disease etiologies were primary hip osteoarthritis (58%) and secondary osteoarthritis due to developmental dysplasia (31%). Rheumatoid arthritis, rapidly destructive coxarthrosis, spondyloepiphyseal dysplasia, childhood infection, and femoral head aseptic necrosis were also causative pathologies. Hip scores significantly improved from 44 to 82 out of 100. Overall implant-associated survival rate after 10 years was 94.1%. Cup loosening was observed in 2 hips, and subsidence >5 mm was observed in 9 hips. Presence of Crowe IV in hips was a significant risk factor for total hip arthroplasty in patients with dwarfism (p < 0.05); leg lengthening had a weak but significant correlation (r = 0.253, p < 0.05).

CONCLUSIONS

Total hip arthroplasty using conventional cementless implants for patients with dwarfism shows good clinical and radiological outcomes and has a relatively low perioperative risk.

Cementation of the highly cross-linked polyethylene liner into a well-fixed acetabular shell to treat patients with recurrent dislocation after total hip arthroplasty

Cementation of a highly cross-linked polyethylene liner into a well-fixed acetabular shell provided a good durability for liner wear. However, its efficacy in treating recurrent instability due to malposition cup is less reported. The aim of this study is to evaluate the outcome of this surgical technique to treat hip instability. From 2009 to 2019, we have identified 38 patients who had been surgically treated for recurrent instability, including cementation liner (N = 20) and revision cup (N = 18) procedures. Patients were followed for a mean of 45.66 months. We have recorded and analyzed all causes of implant failure including recurrent instability. Clinical outcomes were assessed including complication and Harris Hip Score (HHS) preoperatively and at the latest follow-up. Revision-free survivorship for any cause was 95.0% at 1 year, and 84.4% at 5 years in cementation liner group and 88.9% at 1 year and 5 years in revision cup group. Mean Harris hip score improved from 48.3 points preoperatively to 79.5 points at the last follow-up in cementation liner group and mean HHS improved from 43.3 points preoperatively to 77.2 points in revision cup group. There were two implant failures in each group, including one is due to persistent hip instability and the other is due to periprosthetic joint infection in the cementation liner group and two implant failure are due to persistent hip instability in the revision cup group. Functional scores and implant survival were similar in both groups. We demonstrated that orientation correction via the cementation of the polyethylene liner into well-fixed acetabular shell is a promising option to treat and prevent instability. Level of Evidence: Therapeutic Level IV.

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

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

Robotics in total hip arthroplasty: a review of the evolution, application and evidence base

Robotic systems used in orthopaedics have evolved from active systems to semi-active systems.

Early active systems were associated with significant technical and surgical complications, which limited their clinical use.

The new semi-active system Mako has demonstrated promise in overcoming these limitations, with positive early outcomes.

There remains a paucity of data regarding long-term outcomes associated with newer systems such as Mako and TSolution One, which will be important in assessing the applicability of these systems.

Given the already high satisfaction rate of manual THA, further high-quality comparative studies are required utilizing outcome scores that are not limited by high ceiling effects to assess whether robotic systems justify their additional expense.

Cite this article: EFORT Open Rev 2020;5:866-873. DOI: 10.1302/2058-5241.5.200037

Factors affecting impingement and dislocation after total hip arthroplasty - Computer simulation analysis

BACKGROUND

Studies on the causes and factors affecting dislocation after total hip arthroplasty have revealed conflicting results. The purpose of this study was to evaluate the factors affecting impingement and dislocation after total hip arthroplasty, using a 3-dimensional dynamic motion analysis.

METHODS

The CT data of 53 patients (53 hips: anterior dislocation; 11 cases, and posterior dislocation; 42 cases) who experienced hip dislocation after total hip arthroplasty with posterior approach, and 120 control patients (120 hips) without dislocation were analyzed. Parameters related to implant alignment, offset and leg length were evaluated. The impingement type was also analyzed using a software.

FINDINGS

Considering implant settings affecting dislocation, patients at risk for posterior dislocation had decreased stem anteversion, combined anteversion, femoral offset, and leg length. Nevertheless, patients at risk for anterior dislocation had only lower leg length, and these patients may also be at risk for a higher incidence of recurrent dislocation. Bony impingement occurred in almost half of the cases with posterior dislocation, while implant impingement was associated with anterior dislocation. Importantly, anterior dislocation was not as common as posterior dislocation even in cases with occurrence of posterior impingement.

INTERPRETATION

Bony impingement substantially affects dislocation even in the situation where the implant position and alignment are determined by the so-called "safe zone", especially on the anterior side, while implant impingement affects anterior dislocation. The restoration of anterior offset (i.e., prescribed by the stem anteversion and femoral offset) and combined anteversion is critical for avoidance of posterior dislocation after total hip arthroplasty.

Current concepts in robotic total hip arthroplasty

INTRODUCTION

Total hip replacement provides mostly fair functional and clinical results. Many factors play an essential role in hip stability and long-term outcomes. Surgical positioning remains fundamental for obtaining accurate implant fit and prevent hip dislocation or impingement. Different categories of robotic assistance have been established throughout the previous years and all of the technologies target accuracy and reliability to reduce complications, and enhance clinical outcomes.

MATERIALS AND METHODS

An overview is proposed over the principles of robotic assistance in hip arthroplasty surgery. Accuracy, reliability, management of the bone stock, clinical outcomes, constraints and limits of this technology are reported, based on recent literature.

RESULTS

Potential advantages regarding pre-operative planning accuracy, cup positioning, maintenance of the center of rotation, preservation of an adequate bone stock nay clinical short- and mid-term outcomes are balanced with some reported disadvantages and limits like hip anatomical specificity, cost-effectiveness, engineering dependence.

DISCUSSION

The use of robotic-assisted THA presents clear and evident benefits related to accurate implant positioning and maintenance of a minimal bone while allowing. For some authors, an early improvement in functional results and patient's recovery. This technology demonstrated a shorter surgical time and a short learning curve required to optimize its use and this technology presents promising outcomes and results and potential use in routine clinical application but its limitation of use is still present especially the cost of the robot, the need for the presence of an engineer during the surgery, its availability of use in all hospitals as well as the difficulty presented in dysplastic or dysmorphic hip joints.

Mortality as a competition risk factor in the survival analysis of the results of the type of fixation of the total hip prosthesis in octogenarian patients

INTRODUCTION

Total hip replacement (THR) is challenging in octogenarians due to associated comorbidities and controversy regarding fixation type. We ask whether cemented THR is superior to uncemented THR in patients above the age of 80 years.

MATERIAL AND METHODS

A total of 382 patients (441 hips) aged 80 years or older who underwent THR between 2004 and 2015 were analysed. A cemented THR was implanted in 196 hips (group 1), an uncemented THR with a grit-blasted stem in 121 (group 2), or with a porous-coated stem in 124 (group 3). Patients in group 1 had a higher mean age, more comorbidities and osteoporotic bone. Survival analysis was calculated using cumulative incidence function to account for the competing risk of death.

RESULTS

Medical complications rate was similar. There were 3post-operative fractures: one in group 2 and 2in group 3. Competing risk analysis showed that the cumulative incidence of revision for any cause was 2.3 in group 1, 6.0 in group 2 and 4.1 in group 3 at 10years, and the cumulative incidence of revision for aseptic loosening was 1.2 in group 1, 3.7 in group 2 and 0 in group 3 at the same period.

CONCLUSIONS

THR presents an acceptable number of adverse events for octogenarian patients. Despite uncemented fixation was satisfactory, the higher peri-prosthetic fracture rate worsens results in this group.

Outcomes of conversion THA after failed porous tantalum implant for osteonecrosis of the femoral head: a comparative matched study

BACKGROUND

As a joint-preserving surgery, porous tantalum implantation (PTI) provides an additional treatment option for osteonecrosis of the femoral head (ONFH). However, conversion to a total hip arthroplasty (THA) after failed PTI is considered a challenging procedure. The purpose of this study was to compare the clinical and radiologic outcomes and complications of THA after failed PTI with those of primary THA without any previous surgery for ONFH.

METHODS

This retrospective study included 32 patients undergoing THA after failed PTI and 25 age, sex, and body mass index matched patients who underwent primary THA without any previous surgery for ONFH between December 2009 and March 2014. All patients were followed for at least 36 months. The postoperative clinical and radiological evaluations were based on Harris Hip Score (HHS) and plain radiographs. The independent sample test and the chi-square test were used for the statistical analysis.

RESULTS

The HHS in the PTI group was similar to that in the primary group at the latest follow-up (p = 0.274), but longer operation time and greater intraoperative blood loss were observed in the PTI group (p < 0.001, respectively). No significant differences in radiological parameters and postoperative complications were found between the 2 groups (p > 0.05).

CONCLUSIONS

THA after PTI showed similar clinical and radiological outcomes to primary THA except for longer operation time and greater intraoperative blood loss.

Natural history of noise and squeaking in cementless ceramic-on-ceramic total hip arthroplasty

Introduction

Ceramic-on-ceramic (COC) total hip arthroplasty (THA) was developed to reduce wear debris, and consequently the occurrence of osteolysis and aseptic loosening. The purpose of the present study was to determine the incidence and natural history of noise including squeaking after COC THA, and to clarify whether clinical outcomes and any demographic and implant-related factors are associated with noise from these ceramic bearings.

Methods

This was a retrospective observational study of 137 primary COC THAs between 2004 and 2009 at our institute. The Mean follow-up was for 10.5 years. All patients were followed up with an office visit to obtain information regarding noise, pain, and function. The correlations between the noise, and patient demographic, radiographic, and implant-related factors were evaluated.

Results

Noise developed in 30 hips (21.9%), specifically squeaking in 2 (1.5%) of the 137 hips during the follow-up period. Noise including squeaking was not associated with pain or functional outcomes. There was significant correlation between noise and cup anteversion, in that cup anteversion of patients with noise was smaller than that in those without noise. No significant correlation was found between noise and any other patient demographic including age, sex, height, body weight, or body mass index. Kaplan-Meier survivorship analysis with revision for any reason and an aseptic loosening of either component as the end point, revealed a cumulative survival rate at 10 years of 98.4% and 99.1% respectively.

Conclusion

The long-term clinical and radiographic outcome of cementless COC THA is excellent, but we should be vigilant for noise from COC bearings.

Ellipse method for measuring Liaw's anteversion of the acetabular component after total hip arthroplasty

BACKGROUND

Several cup anteversion measurements for post-operative total hip arthroplasty (THA) surgery have been described. We developed the standardized Liaw's trigonometric method to eliminate the influence of patient position, which is the most accurate method for cup anteversion measurement. We then developed an ellipse method using the Elliversion software and reported an interobserver error reduction in 2013. In this study, we attempted to apply this ellipse method in the clinic and compared its accuracy with the standard trigonometric version.

METHODS

In the present study, we attempted to incorporate the ellipse method with Liaw's standardized anteversion in the simulated cup position. We measured standardized Liaw's anteversion for 434 radiographs in the clinic using the ellipse method. Repeated standard deviation (RSD) was calculated for accuracy evaluation. Furthermore, paired t-test was used for comparison with the interobserver and intraobserver errors.

RESULTS

We found that the standardized Liaw's anteversion measured using the ellipse method showed lower RSD than the radiographic version. RSD was 0.795 in the standardized Liaw's anteversion with ellipse method group. The p-values of the paired t-test were all higher than 0.05 when measuring the interobserver and intraobserver errors. It indicated that the ellipse method was a precise and simple tool for cup anteversion measurement.

CONCLUSION

We believe that this ellipse measurement can assist surgeons while placing the acetabulum cup into the precise position and enable early diagnosis of acetabulum loosening.

Improvement of locomotive syndrome after total hip arthroplasty: A two-year longitudinal cohort study

OBJECTIVES

Patients requiring total hip arthroplasty (THA) may possibly have locomotive syndrome (LS). Therefore, we investigated changes of LS in patients undergoing THA and clarified key factors that affected LS stage.

METHODS

A prospective cohort study was conducted with 88 patients undergoing THA (74 females, 14 males, mean age: 67.6 years). Data collected using LS stage, stand-up test, two-step test, and 25-question Geriatric Locomotive Function Scale results were evaluated before THA, and 6 months, 1 year, and 2 years after THA. Key factors were determined using multivariate analysis and receiver operating characteristic (ROC) curve analysis.

RESULTS

Before THA, all patients had fallen LS (stage1: 3.4% and stage2: 96.6%). Overall, 56.8% patients improved their LS stage, and 17.0% of patients overcame LS at 2 years after THA. The key factors that affected LS stage were preoperative two-step test and age. ROC analyses showed a preoperative two-step test score of 0.988 and an age of 67.5 years as a cut-off value for the change of LS stage.

CONCLUSIONS

Patients experiencing LS due to hip disorders have the potential to recover after THA. Additional postoperative training may be beneficial for patients with low preoperative two-step test scores to improve their LS stage.

Total Hip Arthroplasty With Trochanteric Ostectomy for Patients With Angular Deformity of the Proximal Femur

BACKGROUND

Total hip arthroplasty (THA) of patients with a proximal femoral deformity is technically demanding. This deformity poses the risk of femoral fracture or perforation; stem malposition; and failed stem fixation. To insert a femoral stem in neutral position with a good fit, we removed the greater trochanter in case of a varus deformity, and the lesser trochanter in case of valgus deformity, while performing THA. We aimed to evaluate stem position, implant stability, clinical results, and radiological changes after THAs using this technique.

METHODS

Fifteen patients (17 hips; 11 varus hips and 6 valgus hips) underwent cementless THA using the trochanteric osteotomy technique in one institution. We evaluated procedure-specific complications: intraoperative femoral fracture, stem malposition, weakness of the abductor power and limp. Modified Harris Hip Score, radiological changes, and the stability of stems were assessed at a mean of 7.1 years of follow-up (range 2.0-15.5).

RESULTS

Femoral fracture occurred during the insertion of the stem in 4 hips. All stems were aligned in neutral position. At the latest follow-up, the mean power of the abductor was 4.3 (range 3-5). Eleven patients had slight limp and 4 patients had moderate limp. All stems had bone-ingrown stability and no stem was revised. The mean modified Harris Hip Score improved from 50 points at the preoperative evaluation to 81 points at the final follow-up.

CONCLUSION

The trochanteric excision enabled neutral insertion of cementless stem in patients with varus/valgus deformity of the proximal femur, and THA using this technique rendered favorable results.