The Insertion of Threaded Acetabulum Components: Indications According to Specific Acetabulum Anatomy and Methods to Avoid Pitfalls

New-generation threaded acetabulum components have been used in total hip arthroplasty (THA) with good outcomes. We have extensively used the EcoFit® SC cup (Implantcast, Buxtehude, Germany) in our practice. In this report, we present some major complications related to the use of this implant, as well as insights regarding the surgical technique to avoid such adverse effects. Furthermore, we attempt to describe certain contraindications for using threaded cups in THA, taking into account specific patient anatomy and intraoperative acetabulum preparation. We have observed acetabulum roof and posterior wall fractures, as well as incomplete placement of the component. Ensuring the meticulous preparation of the peripheral rim of the acetabulum is crucial to prevent incomplete placement since threaded components have a larger diameter than that of the reamers used to prepare the acetabulum. Additionally, when dealing with the acetabula where the posterior or anterior walls have thinned, it is advisable to refrain from using a threaded cup to avoid the risk of intraoperative fractures caused by the torque forces exerted during implant insertion.

High-resolution ultrasound in the evaluation of the adult hip

This paper reviews ultrasound of the hip, which is a commonly requested examination for symptomatic hip issues. This includes both intra-articular and extra-articular causes of hip pain. Ultrasound is easily accessible, lacks radiation exposure, and allows for evaluation of the contralateral hip as well as assessment of dynamic maneuvers. Ultrasound can be used to guide interventional procedures. Ultrasound of the hip can be challenging due to the deep location of structures and complex anatomy. Typically, high-frequency transducers are used to examine the hip, however the choice of ultrasound transducer depends on the patient's body habitus, with lower frequency transducers required to penetrate deep structures in obese patients. It is important to have an approach to ultrasound of the hip which includes assessment of the anterior, lateral, posterior, and medial aspects of the hip. The technique and relevant anatomy of each of these compartments are discussed as well as the use of Doppler examination of the hip. Several dynamic maneuvers can be performed to help determine the cause of hip pathology in various locations, and these are described and illustrated. Ultrasound is useful for guided procedures about the hip, and these indications will be reviewed.

Correlation of hip capsule morphology with patient symptoms from femoroacetabular impingement

The relationship between morphological characteristics of the hip capsule and patient symptoms in the setting of femoroacetabular impingement (FAI) is undefined. In this study, patients with symptomatic FAI prospectively underwent 3T magnetic resonance (MR) imaging of the affected hip and completed the hip disability and osteoarthritis outcome score (HOOS) to determine the correlation between hip capsule anatomy and patient symptoms. Anterior hip capsule volume, posterior capsule volume, anterior-posterior capsule volume ratio, and proximal-distal volume ratio in the anterior capsule were quantified and measured using axial-oblique intermediate-weighted 3D fast spin echo MR images. A total of 35 patients (35 hips) were included for analysis (mean age: 30.6 years; mean body mass index [BMI]: 24.9 kg/m² ; 57% male). The mean alpha angle was 62.2° ± 4.7°, the mean anterior hip capsule volume was 1705.1 ± 450.3 mm³ , the mean posterior hip capsule volume was 1284.8 ± 268.5 mm³ , the mean anterior to posterior capsule volume ratio was 1.1 ± 0.39, and the mean proximal to distal volume ratio of the anterior capsule was 0.65 ± 0.28. There was no correlation between age, gender, or BMI, and any hip capsule characteristics. Worse scores on the HOOS pain scale were correlated with increased anterior to posterior volume ratio (r = -.38; 95% confidence interval: -0.06 to -0.63). In conclusion, hip capsule morphology correlates with patient symptoms in the setting of FAI as increased anterior capsular volume, relative to posterior capsular volume, is associated with greater patient pain.

The calcar femorale: A new perspective

It is the role of the hip joint to support the superincumbent body weight while its complex range of movement, under a variety of stresses, allows the individual to undertake a wide range of physical activities. It is then perhaps not surprising that a recent anatomical study shows that the upper femur has a structure commensurate with the complexity of its movements. Mechanically, the upper femur consists of two separate bones: the combined femoral head and neck and the femoral shaft. Both bones consist of a mixture of two different types: cancellous bone and cortical bone, each with its own characteristics. Both bones are subjected to two different forces: those of weight bearing and movement and those of bone modelling. In the face of these complexities, this article tenders some theoretical considerations as to how this region functions and deals with these particular problems. From an anatomical viewpoint, the calcar femorale plays a central role in the mechanical structure of the femoral neck and is pivotal in the management of the stresses to which the region is subjected.

Calibration Marker Position in Digital Templating of Total Hip Arthroplasty

BACKGROUND

We report a mathematical method to assess the vertical and horizontal positions of spherical radiopaque objects of known size in conventional radiographs.

METHODS

The reliability and validity of the method were tested in an experimental setting and applied to 100 anteroposterior pelvic radiographs with external calibration markers and unilateral total hip arthroplasty (THA).

RESULTS

We found excellent reliabilities; intraclass correlation coefficients for interobserver and intraobserver reliabilities were 0.999-1.000 (P = .000). The mean normal height of THA was 198 mm (range: 142-243 mm, standard deviation: 18 mm) above the detector. Vertical and horizontal external marker positions differed significantly from the true hip center (THA; P < .001 and P = .017).

CONCLUSION

This method could enhance patient safety by enabling automated detection of malpositioned calibration markers by templating software.

The Influence of Hip Rotation on Femoral Offset Following Short Stem Total Hip Arthroplasty

Short stem total hip arthroplasty (THA) is thought to be an advantageous surgical option for young patients. Femoral offset has been identified as an important factor for clinical outcome of THA. However, little is known on functional implications of femoral offset after short stem THA. Importantly, hip rotation influences the projected femoral offset and may lead to significant underestimation. Therefore, a novel method to identify and account for hip rotation was applied to a prospectively enrolled series of 37 patients (48 radiographs) undergoing short stem THA. Repeated measurements were performed and intraobserver and interobserver reliability was assessed and femoral offset was corrected for rotation. Based on this study, rotation-correction of femoral offset is of highest relevance for the correct interpretation in future studies.

Femoral Offset (3D) in Patients without Osteoarthritis - Index Values from 200 Hip Joints

Introduction:

Femoral offset (FO) is a crucial parameter for hip joint biomechanics. Reference values for FO are particularly important when joint geometry has to be reconstructed during surgical interventions. Such reference values are scarce in literature and have mainly been obtained from osteoarthritis (OA) patients. The aim of this study was to conduct a patient-specific study of FO without osteoarthritis and to create a dataset of FO index values.

Materials and Methodology:

One hundred (49 female, 51 male; mean age: 59 (18 - 83) years) pelvic computed tomography (CT) scans were analyzed to determine FO in each patient. Bilateral symmetry and correlation between demographic data and FO were analyzed.

Results:

The mean FO ± SD was different for male (4.36 ± 0.56 cm) and female patients (3.95 ± 0.35 cm) (p <.0001). No Side differences of FO were observed in male and female patients. Significant correlation between height and FO was only observed in male patients.

Conclusion:

The values obtained in this study can be used as index values for the restoration and evaluation of hip geometry. For men, FO can be approximated using the correlation between FO and height.