Hip centre of rotation

PURPOSE: Various anatomical landmarks have become established in radiography for the assessment of cup positioning after total hip arthroplasty (THA). The most important one is Koehler's teardrop figure (KTF). However, there is a lack of data on the validity of this landmark, which is widely used clinically for assessing the centre of rotation of the hip. METHOD: A retrospective measurement of the lateral and cranial distance of the KTF to the centre of hip rotation was performed on the basis of 250 X-ray images of patients who had undergone THA...

PURPOSE: Although spinal pathology or fusion can change patients' posture and pelvic orientation, their correlation with perception of limb length discrepancy (LLD) after total hip arthroplasty (THA) is not well understood. We hypothesised that LLD perception after THA would not correlate with a history of spinal pathology, fusion or sagittal lumbar spine stiffness among patients who underwent THA. METHODS: Four hundred consecutive patients who underwent THA and had a complete set of anteroposterior and lateral EOS® imaging in standing and sitting positions were included in this retrospective case-control study...

The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients. All patients who underwent a knee arthroplasty from 2019 to 2021 were included. Exclusion criteria were genu valgus, flexion contracture (> 5°), previous femoral osteotomy or fracture, total hip arthroplasty, and femoral rotational disorder...

The assessment of three-dimensional (3D) bony defects is important to inform the surgical planning of hip reconstruction. Mirroring of the contralateral side has been previously used to measure the hip centre of rotation (CoR). However, the contralateral side may not be useful when diseased or replaced. Statistical Shape Models (SSMs) can aid reconstruction of patient anatomy. Previous studies have been limited to computational models only or small patient cohorts. We used SSM as a tool to help derive landmarks that are often absent in hip joints of patients with large acetabular defects...

Mechanical energy fluctuation of the segments of lower limbs during walking has not been fully investigated. It was hypothesized that the segments may work as a pendulum, i.e. the kinetic and potential energies exchanged out of phase. This study aimed to investigate energy changes and recovery during gait in hip replacement patients. The gait data for 12 participants with total hip replacement and 12 age-matched control was compared. The kinetic, potential and rotative energies for whole lower limb and thigh, calf and foot, were calculated...

PURPOSE: Pelvic tilt (PT) is important to consider when planning total hip arthroplasty (THA) due to its dynamic impact on acetabular orientation. The degree of sagittal pelvic rotation varies during functional activities and can be difficult to measure without proper imaging. The purpose of this study was to evaluate PT variation in the supine, standing, and seated positions. METHODS: A multi-centre cross-sectional study was performed that included 358 THA patients who had preo-perative PT measured from supine CT scan and standing and upright seated lateral radiographs...

PURPOSE: Medial acetabular bone defects are frequently encountered in revision total hip arthroplasty (THA), but few studies have focused on their reconstruction. This study aimed to report the radiographic and clinical results after medial acetabular wall reconstruction using metal disc augments in revision THA. METHODS: Forty consecutive revision THA cases using metal disc augments for medial acetabular wall reconstruction were identified. Post-operative cup orientation, the centre of rotation (COR), stability of acetabular components and peri-augments osseointegration were measured...

Standard practice for acetabular component placement in total hip arthroplasty (THA) is to medialise the acetabular component. Bone preservation techniques during primary THA are beneficial for possible future revisions. The goal of this study is to examine the effect of downsizing and minimising medialisation of the acetabular component on bone resection volume. The volume of bone resected during acetabular preparation for different sizes of components was calculated and the volume of bone preserved by downsizing the cup was determined...

INTRODUCTION: Arthroscopic labral procedures are frequently undertaken in patients with femoroacetabular impingement (FAI). The role of arthroscopic femoral neck osteoplasty is well established, but less is known about labral procedures. This study evaluates the midterm efficacy and feasibility of arthroscopic osteoplasty with concomitant labral debridement for cam impingement in active adults. METHODS: The present study was conducted according to the STROBE Statement...

INTRODUCTION: Acetabular revision surgery is a surgical challenge, especially when complex bone defects appear. This makes primary fixation and osseointegration of the implants difficult, which conditions the appearance of complications. Trabecular titanium implants attempt to solve these problems. OBJECTIVES: To evaluate our clinical-radiological results, the survival of the implants and the appearance of mid-term complications in acetabular revision surgery in a series of 37 acetabular replacements with Paprosky type IIIA and IIIB bone defects in which a trabecular titanium cup-cage revision implant was used...

BACKGROUND: Femoral neck fractures are intracapsular hip fractures. There are several surgical implants that have been used to treat femoral neck fractures. Depuy Synthes Products and the lower extremity expert group have developed an innovative femoral neck system (FNS) for fixing femoral neck fractures. With minimally invasive procedures, FNS can provide angular stability. MATERIALS AND METHODS: A non-randomized single centre prospective study was conducted in 30 patients of less than 60 years of age at Maharishi Markandeshwar Institute of Medical Sciences and Research between August 2020 to May 2022...

INTRODUCTION: Accurate implant positioning, tailored to the phenotype and unique biomechanics of each patient is the single most important objective in achieving stability in THA and maximise range of motion. The spine-pelvis-hip construct functions as a single unit adapting to postural changes. It is widely accepted in the literature that no universaltarget exists and variations in spinopelvic mobility mandate adjustments to the surgical plan; thus bringing to the fore the concept of personalised, functional component positioning...

INTRODUCTION: Tibia valga, an extra-articular valgus deformity of the tibia, is common in valgus knees and can result in component misplacement and early total knee arthroplasty (TKA) failure. However, the prevalence and importance of tibia valga in TKA have been seldom reported. This study aims to describe the prevalence and characteristics of tibia valga morphology in valgus knees and describe implications for surgical planning in primary TKA. METHODS: We prospectively examined pre-operative weightbearing whole-body EOS digital radiographs of patients with knee osteoarthritis listed for TKA between December 2018 and December 2020...

Robotic-arm-assisted total hip arthroplasty (RoTHA) offers the opportunity to improve the implant positioning and restoration of native hip mechanics. The concept of individualised, functional implant positioning and how it relates to spinopelvic imbalance is an important yet rather novel consideration in THA. There is mounting evidence that a significant percentage of dislocations occur within the perceived "safe zones"; hence, in the challenging subset of patients with a stiff spinopelvic construct, it is imperative to employ individualised component positioning based on the patients' phenotype...

PURPOSE: The aim was to investigate the contribution of robotics assisted total hip arthroplasty (THA) through direct anterior approach (DAA) in improving radiographic precision, functional results and complications. METHODS: This retrospective study compared 100 primary conventional THA (cTHA) to 50 primary robotic THA (rTHA) through DAA. All cups were placed with the objective of having no anterior overhang while respecting the safe zones (SZ). Radiographic analysis included cup inclination and anteversion, vertical and horizontal changes of the rotation centre (ΔVCOR, ΔHCOR), acetabular and femoral offset...

BACKGROUND AND PURPOSE: Inducible displacement CT compares 2 CTs acquired in series but with alternated rotation of the femur. This provides visual and quantitative clues as to the mechanical situation, i.e., loosening, of a total hip arthroplasty. We report the accuracy of this method as well as the experience of integrating it into a clinical workflow. PATIENTS AND METHODS: This was a retrospective single centre study of 72 cases of suspected aseptic loosening were the surgeon after reviewing a standard plain radiograph saw a need for more information...

The aim of this study was to determine the effect of surgical change to the acetabular offset and femoral offset on the abductor muscle and hip contact forces after primary THA using computational methods. Thirty-five patients undergoing primary THA were recruited. Patients underwent a computed tomography scan of their pelvis and hip, and underwent gait analysis pre- and 6-months post-operatively. Surgically induced changes in acetabular and femoral offset were used to inform a musculoskeletal model to estimated abductor muscle and hip joint contact forces...

AIMS: Dislocation of the hip remains a major complication after periacetabular tumour resection and endoprosthetic reconstruction. The position of the acetabular component is an important modifiable factor for surgeons in determining the risk of postoperative dislocation. We investigated the significance of horizontal, vertical, and sagittal displacement of the hip centre of rotation (COR) on postoperative dislocation using a CT-based 3D model, as well as other potential risk factors for dislocation...

AIMS: The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants. METHODS: A consecutive series of 45 (2014 to 2019) PPRs for Paprosky III defects at rTHA were analyzed comparing the preoperative planning CT scans used to manufacture the implants with postoperative CT scans and radiographs...

INTRODUCTION: Acetabular revision surgery is a surgical challenge, especially when complex bone defects appear. This makes primary fixation and osseointegration of the implants difficult, which conditions the appearance of complications. Trabecular titanium implants attempt to solve these problems. OBJECTIVES: To evaluate our clinical-radiological results, the survival of the implants and the appearance of mid-term complications in acetabular revision surgery in a series of 37 acetabular replacements with Paprosky type IIIA and IIIB bone defects in which a trabecular titanium cup-cage revision implant was used...