This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy. Five subjects with valgus, 12 with neutral, and ten with varus limb alignment were assessed during multiple complete cycles of level walking, downhill walking, and stair descent using a combination of dynamic videofluoroscopy, ground reaction force plates, and optical motion capture. Following 2D/3D registration, tibiofemoral kinematics and kinetics were compared between the three limb alignment groups.Aims
Methods
Spinopelvic characteristics influence the hip’s biomechanical behaviour. However, to date there is little knowledge defining what ‘normal’ spinopelvic characteristics are. This study aims to determine how static spinopelvic characteristics change with age and ethnicity among asymptomatic, healthy individuals. This systematic review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to identify English studies, including ≥ 18-year-old participants, without evidence of hip or spine pathology or a history of previous surgery or interventional treatment, documenting lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI). From a total of 2,543 articles retrieved after the initial database search, 61 articles were eventually selected for data extraction.Aims
Methods
Orthopaedic surgeons are currently faced with an overwhelming number of choices surrounding total knee arthroplasty (TKA), not only with the latest technologies and prostheses, but also fundamental decisions on alignment philosophies. From ‘mechanical’ to ‘adjusted mechanical’ to ‘restricted kinematic’ to ‘unrestricted kinematic’ — and how constitutional alignment relates to these — there is potential for ambiguity when thinking about and discussing such concepts. This annotation summarizes the various alignment strategies currently employed in TKA. It provides a clear framework and consistent language that will assist surgeons to compare confidently and contrast the concepts, while also discussing the latest opinions about alignment in TKA. Finally, it provides suggestions for applying consistent nomenclature to future research, especially as we explore the implications of 3D alignment patterns on patient outcomes. Cite this article:
We aimed to investigate if the use of the largest possible cobalt-chromium head articulating with polyethylene acetabular inserts would increase the in vivo wear rate in total hip arthroplasty. In a single-blinded randomized controlled trial, 96 patients (43 females), at a median age of 63 years (interquartile range (IQR) 57 to 69), were allocated to receive either the largest possible modular femoral head (36 mm to 44 mm) in the thinnest possible insert or a standard 32 mm head. All patients received a vitamin E-doped cross-linked polyethylene insert and a cobalt-chromium head. The primary outcome was proximal head penetration measured with radiostereometric analysis (RSA) at two years. Secondary outcomes were volumetric wear, periacetabular radiolucencies, and patient-reported outcomes.Aims
Methods
Differences at motor control strategies to provide dynamic balance in various tasks in diabetic polyneuropatic (DPN) patients due to losing the lower extremity somatosensory information were reported in the literature. It has been stated that dynamics of
The aetiologies of common degenerative spine, hip, and knee pathologies are still not completely understood. Mechanical theories have suggested that those diseases are related to sagittal pelvic morphology and spinopelvic-femoral dynamics. The link between the most widely used parameter for sagittal pelvic morphology, pelvic incidence (PI), and the onset of degenerative lumbar, hip, and knee pathologies has not been studied in a large-scale setting. A total of 421 patients from the Cohort Hip and Cohort Knee (CHECK) database, a population-based observational cohort, with hip and knee complaints < 6 months, aged between 45 and 65 years old, and with lateral lumbar, hip, and knee radiographs available, were included. Sagittal spinopelvic parameters and pathologies (spondylolisthesis and degenerative disc disease (DDD)) were measured at eight-year follow-up and characteristics of hip and knee osteoarthritis (OA) at baseline and eight-year follow-up. Epidemiology of the degenerative disorders and clinical outcome scores (hip and knee pain and Western Ontario and McMaster Universities Osteoarthritis Index) were compared between low PI (< 50°), normal PI (50° to 60°), and high PI (> 60°) using generalized estimating equations.Aims
Methods
Dissatisfaction following total knee arthroplasty is a well-documented phenomenon. Although many factors have been implicated, including modifiable and nonmodifiable patient factors, emphasis over the past decade has been on implant alignment and stability as both a cause of, and a solution to, this problem. Several alignment targets have evolved with a proliferation of techniques following the introduction of computer and robotic-assisted surgery. Mechanical alignment targets may achieve mechanically-sound alignment while ignoring the soft tissue envelope; kinematic alignment respects the soft tissue envelope while ignoring the mechanical environment. Functional alignment is proposed as a hybrid technique to allow mechanically-sound, soft tissue-friendly alignment targets to be identified and achieved. Cite this article:
Introduction. Untreated hip osteoarthritis is a debilitating condition leading to pain, bone deformation, and limited range of motion. Unfortunately, studies have not been conducted under in vivo conditions to determine progressive kinematics variations to a hip joint from normal to pre-operative and post-operative THA conditions. Therefore, the objective was this study was to quantify normal and degenerative hip kinematics, compared to post-operative hip kinematics. Methods. Twenty unique subjects were analyzed; 10 healthy, normal subjects and 10 degenerative, subjects analyzed pre-operatively and then again post-operatively after receiving a THA. During each assessment, the subject performed a gait (stance and swing phase) activity under mobile, fluoroscopic surveillance. The normal and diseased subjects had CT scans in order to acquire bone geometry while implanted subjects had corresponding CAD models supplied. Femoral head and acetabular cup centers were approximated by spheres based on unique geometries while the component centers were pre-defined as the
Patient-specific instrumentation of total knee arthroplasty (TKA) is a technique permitting the targeting of individual kinematic alignment, but deviation from a neutral mechanical axis may have implications on implant fixation and therefore survivorship. The primary objective of this randomized controlled study was to compare the fixation of tibial components implanted with patient-specific instrumentation targeting kinematic alignment (KA+PSI) A total of 47 patients due to undergo TKA were randomized to KA+PSI (n = 24) or MA+CAS (n = 23). In the KA+PSI group, there were 16 female and eight male patients with a mean age of 64 years (Aims
Patients and Methods
Background. Balance impairment and falling are of the major health problems in elderly individuals. The ability to maintain standing balance influences the risk of falling while performing everyday activities. Postural control is the base of balance that is the result of collaboration of visual, vestibular and somatosensory systems. Single leg stance test is a simple clinical method to evaluate static balance. In this test, the
Taper junctions between modular hip arthroplasty femoral heads and stems fail by wear or corrosion which can be caused by relative motion at their interface. Increasing the assembly force can reduce relative motion and corrosion but may also damage surrounding tissues. The purpose of this study was to determine the effects of increasing the impaction energy and the stiffness of the impactor tool on the stability of the taper junction and on the forces transmitted through the patient’s surrounding tissues. A commercially available impaction tool was modified to assemble components in the laboratory using impactor tips with varying stiffness at different applied energy levels. Springs were mounted below the modular components to represent the patient. The pull-off force of the head from the stem was measured to assess stability, and the displacement of the springs was measured to assess the force transmitted to the patient’s tissues.Objectives
Methods
Introduction. Subluxation and dislocation are frequently cited reasons for THA revision. For patients who cannot accommodate a larger femoral head, an offset liner may enhance stability. However, this change in biomechanics may impact the mechanical performance of the bearing surface. To our knowledge, no studies have compared wear rates of offset and neutral liners. Herein we radiographically compare the in-vivo wear performance of 0mm and 4mm offset acetabular liners. Methods. Two cohorts of 40 individuals (0mm, 4mm offset highly crosslinked acetabular liners, respectively) were selected from a single surgeon's consecutive caseload. All patients received the same THA system via the posterior approach. AP radiographs were taken at 6-week (‘pre’) and 5-year (‘post’) postoperative appointments. Patients with poor radiograph quality were excluded (n. 0mm. =5, n. 4mm. =4). Linear and volumetric wear were quantified according to Patent US5610966A. Briefly, images were processed in computer aided design (CAD) software. Differences in vector length between the center of the femoral head and the acetabular cup (pre- and post-vector, Figure 1) allow for calculation of linear wear and wear rate. The angle (β) between the linear wear vector and the cup inclination line was quantified (Figure 1). Patients with negative β were excluded from volumetric analyses (n. 0mm. =11, n. 4mm. =7). Volumetric wear was accordingly calculated accounting for wear vector direction. The results from three randomly selected patients were compared to results achieved using the “Hip Analysis Suite” software package (UChicagoTech). Results. Linear wear rate (Figure 2A) for 0mm offsets was significantly lower than the 4mm offsets (0.011±0.091 vs. 0.080±0.122mm/yr, p=0.008). Volumetric wear rate (Figure 2B) for 0mm offsets was significantly lower than the 4mm offsets (30.37±20.45 versus 61.58±42.14mm. 3. /year, p=0.001). Demographic differences existed between the two cohorts (age, gender, femoral head size, and acetabular cup size). However, there were no significant correlations found between linear/volumetric wear rate and any demographic including age, gender, BMI, femoral head size, or acetabular cup size. Validation showed no significant differences between the CAD method used herein and the gold standard method (0.083±0.014 versus 0.093±0.041mm/year, p=0.71). Discussion. This study is the first to show that 0mm offset liners have significantly lower linear and volumetric wear rates than do 4mm offset liners. Despite this difference, no revisions have been required in either cohort. The linear wear rates computed in this study are below literature-reported clinically relevant values for wear-induced-osteolysis (∼0.10mm/year). As such, the clinical impact of this wear rate difference is unknown. The higher wear rate in the offset group may owe to the altered biomechanics of the construct. By lateralizing the femoral head through an offset liner, the femur is lateralized with respect to the patient's
The purpose of this study was to analyse the biomechanics of
walking, through the ground reaction forces (GRF) measured, after
first metatarsal osteotomy or metatarsophalangeal joint (MTP) arthrodesis. A total of 19 patients underwent a Scarf osteotomy (50.3 years,
standard deviation (Aims
Patients and Methods
For a proper rehabilitation of the knee following knee arthroplasty, a comprehensive understanding of bony and soft tissue structures and their effects on biomechanics of the individual patient is essential. Musculoskeletal models have the potential, however, to predict dynamic interactions of the knee joint and provide knowledge to the understanding of knee biomechanics. Our goal was to develop a generic musculoskeletal knee model which is adaptable to subject-specific situations and to use in-vivo kinematic measurements obtained under full-weight bearing condition in a previous Upright-MRI study of our group for a proper validation of the simulation results. The simulation model has been developed and adapted to subject-specific cases in the multi-body simulation software AnyBody. For the implementation of the knee model a reference model from the AnyBody Repository was adapted for the present issue. The standard hinge joint was replaced with a new complex knee joint with 6DoF. The 3D bone geometries were obtained from an optimized MRI scan and then post-processed in the mesh processing software MeshLab. A homogenous dilation of 3 mm was generated for each bone and used as articulating surfaces. The anatomical locations of viscoelastic ligaments and muscle attachments were determined based on literature data. Ligament parameters, such as elongation and slack length, were adjusted in a calibration study in two leg stance as reference position. For the subject-specific adaptation a general scaling law, taking segment length, mass and fat into account, was used for a global scaling. The scaling law was further modified to allow a detailed adaption of the knee region, e.g. align the subject-specific knee morphology (including ligament and muscle attachments) in the reference model. The boundary conditions were solely described by analytical methods since body motion (apart from the knee region) or force data were not recorded in the Upright-MRI study. Ground reaction forces have been predicted and a single leg deep knee bend was simulated by kinematic constraints, such as that the
Summary Statement. Simulated increases in body weight led to increased displacement, von Mises stress, and contact pressure in finite element models of the extended and flexed knee. Contact shifted to locations of typical medial osteoarthritis lesions in the extended knee models. Introduction. Obesity is commonly associated with increased risk of osteoarthritis (OA). The effects of increases in body weight and other loads on the stresses and strains within a joint can be calculated using finite element (FE) models. The specific effects for different individuals can be calculated using subject-specific FE models which take individual geometry and forces into account. Model results can then be used to propose mechanisms by which damage within the joint may initiate. Patients & Methods. Twelve subject-specific FE models (Abaqus 6.11) of three normal healthy subjects were created by combining geometry (3T T1-weighted MRI scans processed using Mimics 13.0, Geomagic Studio 11, and SolidWorks 2010) and load cases (Vicon and AMTI motion analysis data processed within AnyBody Technology Version 3.0 and Matlab R2007a). Model geometry included the femur and tibia (rigid bodies), tibial cartilage and femoral cartilage (E = 12 MPa, ν = 0.45), and menisci (E. circumferential. = 120 MPa, ν. circumferential. = 0.2; E. axial/radial. = 20 MPa, ν. axial/radial. = 0.3). The tibia was held fixed while loads were applied to the
Few studies have examined the order in which
a spinal osteotomy and total hip replacement (THR) are to be performed
for patients with ankylosing spondylitis. We have retrospectively
reviewed 28 consecutive patients with ankylosing spondylitis who
underwent both a spinal osteotomy and a THR from September 2004
to November 2012. In the cohort 22 patients had a spinal osteotomy
before a THR (group 1), and six patients had a THR before a spinal
osteotomy (group 2). The mean duration of follow-up was 3.5 years
(2 to 9). The spinal sagittal Cobb angle of the vertebral osteotomy
segment was corrected from a pre-operative kyphosis angle of 32.4
(SD 15.5°) to a post-operative lordosis 29.6 (SD 11.2°) (p <
0.001). Significant improvements in pain, function and range of
movement were observed following THR. In group 2, two of six patients
had an early anterior dislocation. The spinal osteotomy was performed
two weeks after the THR. At follow-up, no hip has required revision
in either group. Although this non-comparative study only involved
a small number of patients, given our experience, we believe a spinal osteotomy
should be performed prior to a THR, unless the deformity is so severe
that the procedure cannot be performed. Cite this article:
Down’s syndrome is associated with a number of
musculoskeletal abnormalities, some of which predispose patients
to early symptomatic arthritis of the hip. The purpose of the present
study was to review the general and hip-specific factors potentially
compromising total hip replacement (THR) in patients with Down’s
syndrome, as well as to summarise both the surgical techniques that
may anticipate the potential adverse impact of these factors and
the clinical results reported to date. A search of the literature
was performed, and the findings further informed by the authors’
clinical experience, as well as that of the hip replacement in Down
Syndrome study group. The general factors identified include a high
incidence of ligamentous laxity, as well as associated muscle hypotonia
and gait abnormalities. Hip-specific factors include: a high incidence
of hip dysplasia, as well as a number of other acetabular, femoral
and combined femoroacetabular anatomical variations. Four studies
encompassing 42 hips, which reported the clinical outcomes of THR
in patients with Down’s syndrome, were identified. All patients
were successfully treated with standard acetabular and femoral components.
The use of supplementary acetabular screw fixation to enhance component
stability was frequently reported. The use of constrained liners
to treat intra-operative instability occurred in eight hips. Survival
rates of between 81% and 100% at a mean follow-up of 105 months
(6 to 292) are encouraging. Overall, while THR in patients with
Down’s syndrome does present some unique challenges, the overall
clinical results are good, providing these patients with reliable
pain relief and good function. Cite this article:
Van Nes rotationplasty may be used for patients
with congenital proximal focal femoral deficiency (PFFD). The lower
limb is rotated to use the ankle and foot as a functional knee joint
within a prosthesis. A small series of cases was investigated to
determine the long-term outcome. At a mean of 21.5 years (11 to
45) after their rotationplasty, a total of 12 prosthetic patients
completed the Short-Form (SF)-36, Faces Pain Scale-Revised, Harris
hip score, Oswestry back pain score and Prosthetic Evaluation Questionnaires,
as did 12 age- and gender-matched normal control participants. A
physical examination and gait analysis, computerised dynamic posturography
(CDP), and timed ‘Up &
Go’ testing was also completed. Wilcoxon
Signed rank test was used to compare each PFFD patient with a matched
control participant with false discovery rate of 5%. There were no differences between the groups in overall health
and well-being on the SF-36. Significant differences were seen in
gait parameters in the PFFD group. Using CDP, the PFFD group had
reduced symmetry in stance, and reduced end point and maximum excursions. Patients who had undergone Van Nes rotationplasty had a high
level of function and quality of life at long-term follow-up, but
presented with significant differences in gait and posture compared
with the control group. Cite this article:
Introduction. Patients with knee osteoarthritis frequently complain that they develop pain in other joints due to over-loading during gait. However, there have been no previous studies examining the effect of knee arthritis on the other weight bearing joints. The aim of this study was to examine the loading of the hips and contra-lateral knee during gait in a cohort of patients pre- and post knee replacement. Methods. Twenty patients with single joint osteoarthritis awaiting knee replacement and 20 healthy volunteers were recruited. Gait analysis during level gait and at self selected speed was performed using a 12 camera Vicon motion analysis system. The ground reaction force was collected using EMG electrodes attached to the medial and lateral hamstrings and quadriceps bilaterally. Patients were invited to return 12 months post-operatively. Data was analysed using the Vicon plug-in-gait model and statistical testing was performed with SPSS v16.0 using ANCOVA to account for gait speed. Results. The mean age of the patients was 69 (range 53-82) and the controls was 70 (range 60-83). Mid-stance moments and knee adduction impulses were elevated at both hips and both knees in patients compared to normal individuals (Impulses: OA Knee=1.87Nms; opposite knee=1.46Nms; controls=0.86Nms; p<0.01) whilst peak moments were not significantly different. Muscular co-contraction was elevated in both knees compared to normal (p<0.01). Ten patients returned for follow up. Correction of varus resulted in improvements in moments at the replaced knee however recovery of moments in the other joints was variable and dependant on alignment, gait speed and their ability to mobilise their
The purpose of this study was to assess the effect of total knee arthroplasty (TKA) on the gait symmetry of patients suffering from osteoarthritis. TKA is an effective method of relieving pain and restoring function but many established outcome measures are subjective and based on patient self-report. This study used clinical gait analysis with the Walkabout Portable Gait MonitorTM (WPGM) to describe pre and post-operative function in a more objective manner. The WPGM is a tri-axial arrangement of accelerometers that a subject wears around the waist, approximating the position of the
