Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Methods. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation. Results. Overall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement. Conclusion. This study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation. Cite this article: Bone Joint Res 2022;11(3):180–188

Aims. Plating displaced proximal humeral fractures is associated with a high rate of screw perforation. Dynamization of the proximal screws might prevent these complications. The aim of this study was to develop and evaluate a new gliding screw concept for plating proximal humeral fractures biomechanically. Methods. Eight pairs of three-part humeral fractures were randomly assigned for pairwise instrumentation using either a prototype gliding plate or a standard PHILOS plate, and four pairs were fixed using the gliding plate with bone cement augmentation of its proximal screws. The specimens were cyclically tested under progressively increasing loading until perforation of a screw. Telescoping of a screw, varus tilting and screw migration were recorded using optical motion tracking. Results. Mean initial stiffness (N/mm) was 581.3 (. sd. 239.7) for the gliding plate, 631.5 (. sd. 160.0) for the PHILOS and 440.2 (. sd. 97.6) for the gliding augmented plate without significant differences between the groups (p = 0.11). Mean varus tilting (°) after 7500 cycles was comparable between the gliding plate (2.6; . sd. 1.9), PHILOS (1.2; . sd. 0.6) and gliding augmented plate (1.7; . sd. 0.9) (p = 0.10). Similarly, mean screw migration(mm) after 7500 cycles was similar between the gliding plate (3.02; . sd. 2.85), PHILOS (1.30; . sd. 0.44) and gliding augmented plate (2.83; . sd. 1.18) (p = 0.13). Mean number of cycles until failure with 5° varus tilting were 12702 (. sd. 3687) for the gliding plate, 13948 (. sd. 1295) for PHILOS and 13189 (. sd. 2647) for the gliding augmented plate without significant differences between the groups (p = 0.66). Conclusion. Biomechanically, plate fixation using a new gliding screw technology did not show considerable advantages in comparison with fixation using a standard PHILOS plate. Based on the finding of telescoping of screws, however, it may represent a valid approach for further investigations into how to avoid the cut-out of screws. Cite this article: Y. P. Acklin, I. Zderic, J. A. Inzana, S. Grechenig, R. Schwyn, R. G. Richards, B. Gueorguiev. Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures. Bone Joint Res 2018;7:422–429. DOI: 10.1302/2046-3758.76.BJR-2017-0356.R1

Aims. Appropriate acetabular component placement has been proposed for prevention of postoperative dislocation in total hip arthroplasty (THA). Manual placements often cause outliers in spite of attempts to insert the component within the intended safe zone; therefore, some surgeons routinely evaluate intraoperative pelvic radiographs to exclude excessive acetabular component malposition. However, their evaluation is often ambiguous in case of the tilted or rotated pelvic position. The purpose of this study was to develop the computational analysis to digitalize the acetabular component orientation regardless of the pelvic tilt or rotation. Methods. Intraoperative pelvic radiographs of 50 patients who underwent THA were collected retrospectively. The 3D pelvic bone model and the acetabular component were image-matched to the intraoperative pelvic radiograph. The radiological anteversion (RA) and radiological inclination (RI) of the acetabular component were calculated and those measurement errors from the postoperative CT data were compared relative to those of the 2D measurements. In addition, the intra- and interobserver differences of the image-matching analysis were evaluated. Results. Mean measurement errors of the image-matching analyses were significantly small (2.5° (SD 1.4°) and 0.1° (SD 0.9°) in the RA and RI, respectively) relative to those of the 2D measurements. Intra- and interobserver differences were similarly small from the clinical perspective. Conclusion. We have developed a computational analysis of acetabular component orientation using an image-matching technique with small measurement errors compared to visual evaluations regardless of the pelvic tilt or rotation. Cite this article: Bone Joint Res 2020;9(7):360–367

Objectives. There are various pin-in-plaster methods for treating fractures of the distal radius. The purpose of this study is to introduce a modified technique of ‘pin in plaster’. Methods. Fifty-four patients with fractures of the distal radius were followed for one year post-operatively. Patients were excluded if they had type B fractures according to AO classification, multiple injuries or pathological fractures, and were treated more than seven days after injury. Range of movement and functional results were evaluated at three and six months and one and two years post-operatively. Radiographic parameters including radial inclination, tilt, and height, were measured pre- and post-operatively. Results. The average radial tilt was 10.6° of volar flexion and radial height was 10.2 mm at the sixth month post-operatively. Three cases of pin tract infection were recorded, all of which were treated successfully with oral antibiotics. There were no cases of pin loosening. A total of 73 patients underwent surgery, and three cases of radial nerve irritation were recorded at the time of cast removal. All radial nerve palsies resolved at the six-month follow-up. There were no cases of median nerve compression or carpal tunnel syndrome, and no cases of tendon injury. Conclusion. Our modified technique is effective to restore anatomic congruity and maintain reduction in fractures of the distal radius. Cite this article: Bone Joint Res 2015;4:176–180

Objectives. Our primary aim was to describe migration of the Exeter stem with a 32 mm head on highly crosslinked polyethylene and whether this is influenced by age. Our secondary aims were to assess functional outcome, satisfaction, activity, and bone mineral density (BMD) according to age. Patients and Methods. A prospective cohort study was conducted. Patients were recruited into three age groups: less than 65 years (n = 65), 65 to 74 years (n = 68), and 75 years and older (n = 67). There were 200 patients enrolled in the study, of whom 115 were female and 85 were male, with a mean age of 69.9 years (sd 9.5, 42 to 92). They were assessed preoperatively, and at three, 12 and, 24 months postoperatively. Stem migration was assessed using Einzel-Bild-Röntgen-Analyse (EBRA). Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), EuroQol-5 domains questionnaire (EQ-5D), short form-36 questionnaire (SF-36,) and patient satisfaction were used to assess outcome. The Lower Extremity Activity Scale (LEAS), Timed Up and Go (TUG) test, and activPAL monitor (energy expelled, time lying/standing/walking and step count) were used to assess activity. The BMD was assessed in Gruen and Charnley zones. Results. Mean varus/valgus tilt was -0.77⁰ and axial subsidence was -1.20 mm. No significant difference was observed between age groups (p ⩾ 0.07). There was no difference according to age group for postoperative WOMAC (p ⩾ 0.11), HHS (p ⩾ 0.06), HOOS (p ⩾ 0.46), EQ-5D (p ⩾ 0.38), patient satisfaction (p ⩾ 0.05), or activPAL (p ⩾ 0.06). Patients 75 years and older had a worse SF-36 physical function (p = 0.01) and physical role (p = 0.03), LEAS score (p < 0.001), a shorter TUG (p = 0.01), and a lower BMD in Charnley zone 1 (p = 0.02). Conclusion. Exeter stem migration is within normal limits and is not influenced by age group. Functional outcome, patient satisfaction, activity level, and periprosthetic BMD are similar across all age groups. Cite this article: N. D. Clement, M. Bardgett, K. Merrie, S. Furtado, R. Bowman, D. J. Langton, D. J. Deehan, J. Holland. Cemented Exeter total hip arthroplasty with a 32 mm head on highly crosslinked polyethylene: Does age influence functional outcome, satisfaction, activity, stem migration, and periprosthetic bone mineral density? Bone Joint Res 2019;8:275–287. DOI: 10.1302/2046-3758.86.BJR-2018-0300.R1

Aims

Mechanical stimulation is a key factor in the development and healing of tendon-bone insertion. Treadmill training is an important rehabilitation treatment. This study aims to investigate the benefits of treadmill training initiated on postoperative day 7 for tendon-bone insertion healing.

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To fully quantify the effect of posterior tibial slope (PTS) angles on joint kinematics and contact mechanics of intact and anterior cruciate ligament-deficient (ACLD) knees during the gait cycle.

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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.

Objectives. To evaluate the applicability of MRI for the quantitative assessment of anterior talofibular ligaments (ATFLs) in symptomatic chronic ankle instability (CAI). Methods. Between 1997 and 2010, 39 patients with symptomatic CAI underwent surgical treatment (22 male, 17 female, mean age 25.4 years (15 to 40)). In all patients, the maximum diameters of the ATFLs were measured on pre-operative T2-weighted MR images in planes parallel to the path of the ATFL. They were classified into three groups based on a previously published method with modifications: ‘normal’, diameter = 1.0 - 3.2 mm; ‘thickened’, diameter > 3.2 mm; ‘thin or absent’, diameter < 1.0 mm. Stress radiography was performed with the maximum manual force in inversion under general anaesthesia immediately prior to surgery. In surgery, ATFLs were macroscopically divided into two categories: ‘thickened’, an obvious thickened ligament and ‘thin or absent’. The imaging results were compared with the macroscopic results that are considered to be of a gold standard. Results. Agreement was reached when comparison was made between groups, based on MRI and macroscopic findings. ATFLs were abnormal in all 39 cases and classified as ten ‘thickened’ and 29 ‘thin or absent’. As to talar tilt stress radiography, a clear cut-off angle, which would allow discrimination between ‘thickened’ and ‘thin or absent’ patients, was not identified. Conclusion. MRI is valuable as a pre-operative assessment tool that can provide the quantitative information of ATFLs in patients with CAI. Cite this article Bone Joint Res 2014;3:241–5

Aims

In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement.

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This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH).

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To evaluate if union of clavicle fractures can be predicted at six weeks post-injury by the presence of bridging callus on ultrasound.

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Restoration of proximal medial femoral support is the keystone in the treatment of intertrochanteric fractures. None of the available implants are effective in constructing the medial femoral support. Medial sustainable nail (MSN-II) is a novel cephalomedullary nail designed for this. In this study, biomechanical difference between MSN-II and proximal femoral nail anti-rotation (PFNA-II) was compared to determine whether or not MSN-II can effectively reconstruct the medial femoral support.

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Second-generation metal-on-metal (MoM) articulations in total hip arthroplasty (THA) were introduced in order to reduce wear-related complications. The current study reports on the serum cobalt levels and the clinical outcome at a minimum of 20 years following THA with a MoM (Metasul) or a ceramic-on-polyethylene (CoP) bearing.

Aims

The diversity of femoral morphology renders femoral component sizing in total hip arthroplasty (THA) challenging. We aimed to determine whether femoral morphology and femoral component filling influence early clinical and radiological outcomes following THA using fully hydroxyapatite (HA)-coated femoral components.

Objectives

Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty for patients who require treatment of single-compartment osteoarthritis, especially for young patients. To satisfy this requirement, new patient-specific prosthetic designs have been introduced. The patient-specific UKA is designed on the basis of data from preoperative medical images. In general, knee implant design with increased conformity has been developed to provide lower contact stress and reduced wear on the tibial insert compared with flat knee designs. The different tibiofemoral conformity may provide designers the opportunity to address both wear and kinematic design goals simultaneously. The aim of this study was to evaluate wear prediction with respect to tibiofemoral conformity design in patient-specific UKA under gait loading conditions by using a previously validated computational wear method.

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To validate the precision of digitally reconstructed radiograph (DRR) radiostereometric analysis (RSA) and the model-based method (MBM) RSA with respect to benchmark marker-based (MM) RSA for evaluation of kinematics in the native hip joint.

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The determination of the volumetric polyethylene wear on explanted material requires complicated equipment, which is not available in many research institutions. Our aim in this study was to present and validate a method that only requires a set of polyetheretherketone balls and a laboratory balance to determine wear.

Objectives

The ability to determine human bone stiffness is of clinical relevance in many fields, including bone quality assessment and orthopaedic prosthesis design. Stiffness can be measured using compression testing, an experimental technique commonly used to test bone specimens in vitro. This systematic review aims to determine how best to perform compression testing of human bone.

Objectives

Normal sagittal spine-pelvis-lower extremity alignment is crucial in humans for maintaining an ergonomic upright standing posture, and pathogenesis in any segment leads to poor balance. The present study aimed to investigate how this sagittal alignment can be affected by severe knee osteoarthritis (KOA), and whether associated changes corresponded with symptoms of lower back pain (LBP) in this patient population.