Abstract. Introduction. There is little literature exploring clinical outcomes of secondarily displaced proximal humerus fractures. The aim of this study was to assess the rate of secondary displacement in undisplaced proximal humeral fractures (PHF) and their clinical outcomes. Methods. This was a retrospective cohort study of undisplaced PHFs at Royal Derby Hospital, UK, between January 2018-December 2019. Radiographs were reviewed for displacement and classified according to Neer's classification. Displacement was defined as translation of fracture fragments by greater than 1cm or 20° of angulation. Patients with pathological, periprosthetic, bilateral, fracture dislocations and head-split fractures were excluded along with those without adequate radiological follow-up. Results. In total, 681 patients were treated with PHFs within the study period and out of those 155 were excluded as above. There were 385 undisplaced PHFs with mean age 70 years (range, 21–97years) and female to male ratio of 3.3:1. There were 88 isolated greater tuberosity fractures, 182 comminuted PHFs and 115 surgical neck fractures. Secondary displacement occurred in 33 patients (8.6%). Mean time to displacement was 14.8 days (range, 5–45days) with surgical intervention required in only 5 patients. In those managed nonoperatively, three had malunion and one had nonunion. No significant differences were noted in ROM between undisplaced and secondarily displaced PHFs. Conclusion. Undisplaced fractures are the most common type of PHF. Rate of secondary displacement is low at 8.6% and can occur up to 7 weeks after injury. Displacement can lead to surgery, but those managed conservatively maintain their ROM at final follow up

Aims. The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures. Methods. A multicentre cross-sectional study was performed in 170 patients who were treated nonoperatively for an acetabular fracture in three level 1 trauma centres. Using the post-injury diagnostic CT scan, the maximum gap and step-off values in the weightbearing dome were digitally measured by two trauma surgeons. Native hip survival was reported using Kaplan-Meier curves. Predictors for conversion to THA were determined using Cox regression analysis. Results. Of 170 patients, 22 (13%) subsequently received a THA. Native hip survival in patients with a step-off ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 94% vs 70% vs 74%). Native hip survival in patients with a gap ≤ 2 mm, > 2 to 4 mm, or > 4 mm differed at five-year follow-up (respectively: 100% vs 84% vs 78%). Step-off displacement > 2 mm (> 2 to 4 mm hazard ratio (HR) 4.9, > 4 mm HR 5.6) and age > 60 years (HR 2.9) were independent predictors for conversion to THA at follow-up. Conclusion. Patients with minimally displaced acetabular fractures who opt for nonoperative fracture treatment may be informed that fracture displacement (e.g. gap and step-off) up to 2 mm, as measured on CT images, results in limited risk on conversion to THA. Step-off ≥ 2 mm and age > 60 years are predictors for conversion to THA and can be helpful in the shared decision-making process. Cite this article: Bone Joint J 2023;105-B(9):1020–1029

Distal radius fractures (DRFs) are common injuries that represent 17% of all adult upper extremity fractures. Some fractures deemed appropriate for nonsurgical management following closed reduction and casting exhibit delayed secondary displacement (greater than two weeks from injury) and require late surgical intervention. This can lead to delayed rehabilitation and functional outcomes. This study aimed to determine which demographic and radiographic features can be used to predict delayed fracture displacement. This is a multicentre retrospective case-control study using radiographs extracted from our Analytics Data Integration, Measurement and Reporting (DIMR) database, using diagnostic and therapeutic codes. Skeletally mature patients aged 18 years of age or older with an isolated DRF treated with surgical intervention between two and four weeks from initial injury, with two or more follow-up visits prior to surgical intervention, were included. Exclusion criteria were patients with multiple injuries, surgical treatment with fewer than two clinical assessments prior to surgical treatment, or surgical treatment within two weeks of injury. The proportion of patients with delayed fracture displacement requiring surgical treatment will be reported as a percentage of all identified DRFs within the study period. A multivariable conditional logistic regression analysis was used to assess case-control comparisons, in order to determine the parameters that are mostly likely to predict delayed fracture displacement leading to surgical management. Intra- and inter-rater reliability for each radiographic parameter will also be calculated. A total of 84 age- and sex-matched pairs were identified (n=168) over a 5-year period, with 87% being female and a mean age of 48.9 (SD=14.5) years. Variables assessed in the model included pre-reduction and post-reduction radial height, radial inclination, radial tilt, volar cortical displacement, injury classification, intra-articular step or gap, ulnar variance, radiocarpal alignment, and cast index, as well as the difference between pre- and post-reduction parameters. Decreased pre-reduction radial inclination (Odds Ratio [OR] = 0.54; Confidence Interval [CI] = 0.43 – 0.64) and increased pre-reduction volar cortical displacement (OR = 1.31; CI = 1.10 – 1.60) were significant predictors of delayed fracture displacement beyond a minimum of 2-week follow-up. Similarly, an increased difference between pre-reduction and immediate post reduction radial height (OR = 1.67; CI = 1.31 – 2.18) and ulnar variance (OR = 1.48; CI = 1.24 – 1.81) were also significant predictors of delayed fracture displacement. Cast immobilization is not without risks and delayed surgical treatment can result in a prolong recovery. Therefore, if reliable and reproducible radiographic parameters can be identified that predict delayed fracture displacement, this information will aid in earlier identification of patients with DRFs at risk of late displacement. This could lead to earlier, appropriate surgical management, rehabilitation, and return to work and function

The aim of this study was to define the long-term outcome following adolescent clavicle fracture. We retrospectively reviewed all adolescent fractures presenting to our region (13–17years) over a 10-year period. Patient reported outcomes were undertaken at a minimum of 4 years post-injury (QuickDASH and EQ-5D) in completely displaced midshaft fractures (Edinburgh 2B, >2cm displacement, n=50) and angulated midshaft fractures (Edinburgh 2A2, >30 degrees angulation, n=32). 677 clavicle fractures were analysed. The median age was 14.8 (IQR 14.0–15.7) and 89% were male. The majority were midshaft (n=606, 89.5%) with either angulation (39.8%) or simple fully displaced (39.1%). Only 3% of midshaft fractures underwent acute fixation (n=18/606), all of which were fully displaced. The incidence of refracture following non-operative management of midshaft fractures was 3.2% (n=19/588), all united with non-operative management. Fracture type, severity of angulation or displacement was not associated with risk of refracture. There was one case of non-union encountered following non-operative management of all displaced midshaft fractures (0.4%, n=1/245). At a mean of 7.6 years following injury, non-operative management of both displaced and angulated fractures had a median QuickDASH was 0.0 (IQR 0.0–2.3), EQ-5D was 1.0 (IQR 1.0–1.0). 97% of angulated fractures and 94% of displaced fractures were satisfied with their final shoulder function. We conclude that Non-operative management of adolescent midshaft clavicle fractures result in excellent functional outcomes with a low rate of complications at long-term follow up. The relative indications for surgical intervention for clavicle fractures in adults do not appear to be applicable to adolescents

INTRODUCTION. Ceramic heads are used in hip revision surgery to mitigate corrosion concerns. Manufacturers recommend using a pristine titanium sleeve in conjunction with a well-fixed metal stem to prevent early failure of the ceramic head. However, the influence of impact force, head size, and sleeve offset on pull-off strength and seating displacement of a revision head assembly is not fully understood. Therefore, the purpose of this study was to investigate the pull-off strength and displacement of commercially available revision ceramic heads and titanium taper sleeve offsets (BIOLOX OPTION, CeramTec GmbH, Plochingen, Germany) while covering a range of clinically relevant impaction forces. METHODS. Two head sizes (28 mm, n = 12 and 36 mm, n = 12) and two taper adapter sleeve offsets (small, n = 12 and extra-large, n =12) were tested in this study. A dynamic impaction rig was constructed to seat the head, sleeve, and stem assembly. Consistent impaction forces were achieved by a dropping a hammer fixed to a lever arm from a pre-determined height onto a standard impactor instrumented with a piezoelectric force sensor (PCB Piezotronics Inc.). Axially applied forces of 2 kN and 6 kN were used to cover a range of typical impaction forces. Three non-contact differential variable reluctance transducers (LORD Sensing Systems) were used to track the displacement of the head relative to the stem. Subsequently, samples were transferred a servo hydraulic testing machine, and a pull-off test was carried out per ISO 7206- 10 to measure the disassembly force. RESULTS. For all head and sleeve combinations assembled at 6 kN, pull-off forces and assembly displacements were over two times the values measured at 2 kN. As expected, an increased assembly force resulted in increased pull-offs and displacements. Head size did not play a significant role on measured outcomes. Regarding sleeve offsets, at assembly of 6 kN mean pull-off forces for extra-large sleeves were reduced by approximately 25% relative to small sleeves. However, at a 2 kN assembly, sleeve offsets did not appear to influence pull-off forces. DISCUSSION. This study assessed the effect of impact assembly force, head size, and sleeve offset on pull-off strength and seating displacement of revision ceramic heads. The data suggests assembly force and sleeve offset may influence the pull-off strength and seating displacement of modular heads used in revision hip arthroplasty. Mean pull-off forces for revision heads were comparable in magnitude and trend to previous studies assessing the linear relationship between assembly force and pull-off force in primary heads (Krull et al., 2017, Rehmer et al., 2012). Lower pull-off forces were observed for extra-large sleeves when compared to small sleeves, indicating, decreased contact at the sleeve and stem interface for extra-large offsets may play a role in reducing pull-off forces

Fractures of the clavicle are relatively common, occurring mostly in younger patients and have historically been managed non-operatively. Recent studies have shown an advantage to surgical reduction and stabilisation of clavicle fractures with significant displacement. Currently, fracture displacement is measured using simple anterior-posterior two-dimensional x-rays of the clavicle. Since displacement can occur in all three-dimensions, however, evaluation of the amount displacement can be difficult and inaccurate. The purpose of this study was to determine the view that provides the most accurate assessment. Nine CT scans of acute displaced clavicle fractures were analysed with AmiraDEV5.2.2 Imaging software. Measurements for degrees of shortening and fracture displacement of the fracture clavicle were taken. Using a segmentation and manipulation module (ITK toolkit), five digitally reconstructed radiographs (DRRs) mimicking antero-posterior x-rays were created for every CT, with each differing by projection angle (ranging from 20° upwards tilt to 20° downwards tilt). Measurements were taken on each DRR using landmarks of entire clavicle length, distance from vertebrae to fracture (medial fragment length), distance from fracture to acromium (lateral fragment length), and horizontal shortening, and then compared to the true measurement obtained from the original CT. For all 9 samples, after comparing the measurements of clavicle fracture displacement in each 2D image, we found that an AP view with a 20° downward tilt yielded displacement measurements closest to the 3D (“gold standard”) measurements. The results agree with previous data collected from cadaveric specimens using physical X-ray film images. DDRs enable creation of multiple standard AP radiographs from which accurate tilt can be measured. The large deviation in measurements on different DRR projections motivates consideration of standardising X-ray projections. A uniform procedure would allow one to correctly evaluate the displacement of clavicular fractures if fracture displacement information is to be utilized in motivating surgical decision-making

Introduction. Ceramic heads are used in hip revision surgery to mitigate corrosion concerns. Manufacturers recommend using a pristine titanium sleeve in conjunction with a well-fixed metal stem to prevent early failure of the ceramic head. However, the influence of impact force, head size, and sleeve offset on pull-off strength and seating displacement of a revision head assembly is not fully understood. Therefore, the purpose of this study was to investigate the pull-off strength and displacement of commercially available revision ceramic heads and titanium taper sleeve offsets (BIOLOX OPTION, CeramTec GmbH, Plochingen, Germany) while covering a range of clinically relevant impaction forces. Methods. Two head sizes (28 mm, n = 12 and 36 mm, n = 12) and two taper adapter sleeve offsets (small, n = 12 and extra-large, n = 12) were tested in this study. A dynamic impaction rig was constructed to seat the head, sleeve, and stem assembly (Fig. 1). Consistent impaction forces were achieved by dropping a hammer fixed to a lever arm from a pre-determined height onto a standard impactor instrumented with a piezoelectric force sensor (PCB Piezotronics Inc.). Axially applied forces of 2 kN and 6 kN were used to cover a range of typical impaction forces. Three non-contact differential variable reluctance transducers (LORD Sensing Systems) were used to track the displacement of the head relative to the stem. Subsequently, samples were transferred to a servo hydraulic testing machine, and a pull-off test was carried out per ISO 7206–10 to measure the disassembly force. Results. For all head and sleeve combinations assembled at 6 kN, pull-off forces and assembly displacements were over two times the values measured at 2 kN. As expected, an increased assembly force resulted in increased pull-offs and displacements. Head size did not play a significant role on measured outcomes. Regarding sleeve offsets, at assembly of 6 kN mean pull-off forces for extra-large sleeves were reduced by approximately 25% relative to small sleeves (Fig 2). However, at a 2 kN assembly, sleeve offsets did not appear to influence pull-off forces. Discussion. This study assessed the effect of impact assembly force, head size, and sleeve offset on pull-off strength and seating displacement of revision ceramic heads. The data suggests assembly force and sleeve offset may influence the pull-off strength and seating displacement of modular heads used in revision hip arthroplasty. Mean pull-off forces for revision heads were comparable in magnitude and trend to previous studies assessing the linear relationship between assembly force and pull-off force in primary heads (Krull et al., 2017, Rehmer et al., 2012). Lower pull-off forces were observed for extra-large sleeves when compared to small sleeves, indicating, decreased contact at the sleeve and stem interface for extra-large offsets may play a role in reducing pull-off forces. Acknowledgment:. The authors would like to thank CeramTec GmbH (Plochingen, Germany) for providing the head, sleeve, and stem implants. For any figures or tables, please contact authors directly

Introduction. Stress shielding is one of the major concerns of load bearing implants (e.g. hip prostheses). Stiff implants cause stress shielding, which is thought to contribute to bone resorption1. On the contrary, low-stiffness implants generate high interfacial stresses that have been related to pain and interfacial micro-movements². Different attempts have been made to reduce these problems by optimizing either the stem design3 or using functionally graded implants (FGI) where the stem's mechanical properties are optimized4. In this way, new additive manufacturing technologies allow fabricating porous materials with well-controlled mesostructure, which allows tailoring their mechanical properties. In this work, Finite Element (FE) simulations are used to develop an optimization methodology for the shape and material properties of a FGI hip stem. The resorbed bone mass fraction and the stem head displacement are used as objective functions. Methodology. The 2D-geometry of a femur model (Sawbones®) with an implanted Profemur-TL stem (Wright Medical Technology Inc.) was used for FE simulations. The stem geometry was parameterized using a set of 8 variables (Figure 1-a). To optimize the stem's material properties, a grid was generated with equally spaced points for a total of 96 points (Figure 1-b). Purely elastic materials were used for the stem and the bone. Two bone qualities were considered: good (Ecortical=20 GPa, Etrabecular=1.5 GPa) and medium (Ecortical=15 GPa, Etrabecular=1 GPa). Poisson ratio was fixed to v=0.3. Loading corresponded to stair climbing. Hip contact force along with abductors, vastus lateralis and vastus medialis muscles were considered5 for a bodyweight of 847 N. The resorbed bone mass fraction was evaluated from the differences in strain energy densities between the intact bone and the implanted bone2. The displacement of the load point on the femoral head was computed. The optimization problem was formulated as the minimization of the resorbed bone mass fraction and the head displacement. It was solved using a genetic algorithm. Results. For the Profemur-TL design, bone resorption was around 36% and 56% for good and medium bone qualities, respectively (Fig. 2). The corresponding head displacements were 11.75 mm and 21.19 mm. Optimized solutions showed bone resorption from 15% to 26% and from 44% to 65% for good and medium bone qualities, respectively. Corresponding head displacements ranged from 11.85 mm to 12.25 mm and from 16.9 mm to 22.6 mm. Conclusion. The obtained set of solutions constitutes an improvement of the implant performance for this functionally graded implant (FGI) compared to the original implant for both bone qualities. From these simulations, the final solution for the FGI could be chosen based on manufacturing restrictions or another performance indicator

Purpose: Treatment of femoral epiphysiolysis with major displacement remains a controversial subject. Open repositioning of the epiphysis via a lateral approach as proposed by Dunn allows nearly anatomic restitution but with a high rate of complications. We report our experience with open repositions via an anterior approach which has been more reliable in our hands. Material and methods: During the last decade, we operated nine hips for epiphysiolysis with major displacement, using the anterior approach to spare the medial circumflex artery. External reduction was not attempted. Preoperative and residual displacement were evaluated using the Southwick technique and according to the position of the femoral head in relation to the Klein line. Early after surgery, a bone scintigram was obtained for all hips. We followed these patients to bone maturity, with a mean follow-up of four years. Results: The early postoperative scintigrams did not reveal any case of insufficient uptake in the femoral head. Mean correction was 43° on the lateral view, with a mean preoperative displacement of 72°. Mean residual displacement after surgery was 23°. After repositioning, position of the epiphysis in relation to the Klein line was not significantly different from the position observed on the healthy side. Postoperatively, leg length discrepancy was 1 cm. At last follow-up, there have been no signs of osteonecrosis, chondrolysis or osteoarthritic degeneration. At mean 44 months follow-up, all of the patients have unlimited activities, including sports. Only one patient complained of mild climate-related pain. Discussion: Compared with the lateral approach with trochanterotomy as proposed by Dunn, we have found the anterior approach technically easier and more reliable in terms of protecting the epiphyseal blood supply. The correction obtained, voluntarily preserving a certain degree of under-correction, associated with resection of a portion of the neck enables repositioning without risking vessel stress. Use of a stable internal fixation which allows early mobilisation would be an explanation of the absence of postoperative chondrolysis. Conclusion: These results appear to be sufficiently encouraging to advocate this technique previously described by PH Martin in 1948

Background. The position of the hip-joint centre of rotation (HJC) within the pelvis is known to influence functional outcome of total hip replacement (THR). Superior, lateral and posterior relocations of the HJC from anatomical position have been shown to be associated with greater joint reaction forces and a higher incidence of aseptic loosening. In biomechanical models, the maximum force, moment-generating capacity and the range of motion of the major hip muscle groups have been shown to be sensitive to HJC displacement. This clinical study investigated the effect of HJC displacement and acetabular cup inclination angle on functional performance in patients undergoing primary THR. Methods. Retrospective study of primary THR patients at the RNOH. HJC displacement from anatomical position in horizontal and vertical planes was measured relative to radiological landmarks using post-operative, calibrated, anterior-posterior pelvic radiographs. Acetabular cup inclination angle was measured relative to the inter-teardrop line. Maximum range of passive hip flexion, abduction, adduction, external and internal rotation were measured in clinic. Patient reported functional outcome was assessed by Oxford Hip Score (OHS) and WOMAC questionnaires. Data analysed using a linear regression model. Results. 109 THRs were studied in 104 patients (69 Female). Mean age at THR=63 years (22-88). Mean follow-up=17 months (11-39 months). Median OHS=16, WOMAC=8. Increasing vertical HJC displacement (in either superior or inferior direction) from anatomical position was associated with worsening OHS (p<0.05) and WOMAC scores (p<0.05) and a reduced range of passive hip flexion (p<0.05). No relationship was found between either horizontal HJC displacement or acetabular cup inclination angle and patient functional outcome. Conclusion. A significant relationship was identified between increasing vertical displacement of the HJC and worsening patient functional outcome. This supports current opinion regarding the disadvantageous consequences of a superiorly displaced HJC in terms of survivorship and function. We therefore advocate an anatomical restoration of HJC position wherever possible

Purpose: The double mobility of the G. Bousquet cup—head-polyethylene,polyethylene metal cup—considerably reduces the risk of total hip arthroplasty displacement. Material and methods: We observed seven cases of “intra-prosthetic” displacement in patients with this type of cup. Progressive wear of the polyethylene retention ring allowed displacement of the femoral head. These displacements occurred in six patients (one bilateral case) aged 43–58 years, on the average ten years after the implantation (range 3.5 – 15 years). All patients underwent revision. Results: The polyethylene retention ring was worn in all cases allowing the femoral head to escape. Revision surgery was performed very early in six hips to change the modular base and the polyethylene ring and re-establish retaining capacity. A satisfactory result was achieved in all cases. One patient required revision five years later to change the prosthesis subsequent to haematogenous infection. Another patient underwent a late revision to change the modular base and the entire cup of a press fit implant. This hip was in excellent condition but revision was decided on because of four dislocations. Discussion: Intra-prosthetic displacement of the polyethylene head of a double-mobility cup is exceptional in our experience. Wear of the retention ring is favoured by different elements: 1) direct phenomena: neck and head diameter causing early contact between the neck and the cup; 2) indirect phenomena: factors limiting the mobility of the polyethylene metal cup couple (fibrosis, repeated interventions, ossification). In our experience, intra-prosthetic displacement occurs more readily in patients with favouring conditions (alcoholism, muscle deficiency, psychiatric disorder, obesity) observed in six of our seven cases. Conclusion: Intra-prosthetic displacement of a double-mobility cup is a possible but exceptional complication requiring a technically simple revision. Some teams use this type of cup systematically and for us is an essential element for preventive treatment in high-risk patients and for curative revision of recurrent dislocation

Lower back pain (LBP) is a global problem. Countless in vitro studies have attempted to understand LBP and inform treatment protocols such as disc replacement devices (DRDs). A common method of reporting results is applying a linear fit to load-displacement behaviour, reporting the gradient as the specimen stiffness in that axis. This is favoured for speed, simplicity and repeatability but neglects key aspects including stiffening and hysteresis. Other fits such as polynomials and double sigmoids better address these characteristics, but solution parameters lack physical representation. The aim of this study was to implement an automated method to fit spinal load-displacement behaviour using viscoelastic models.

Six porcine lumbar spinal motion segments were dissected to produce isolated disc specimens. These were potted in Wood's metal, ensuring the disc midplane remained horizontal, sprayed with 0.9% saline and wrapped in saline-soaked tissue and plastic wrap to prevent dehydration. Specimens were tested using the University of Bath spine simulator operating under position control with a 400N axial preload.

Specimens were approximated using representative viscoelastic elements. These models were constructed in MATLAB Simulink R2020b using the SimScape library. Solution coefficients were determined by minimizing the sum of squared errors cost function using a non-linear least squares optimization method.

The models matched experimental data well with a mean % difference in model and specimen enclosed area below 6% across all axes. This indicates the ability of the model to accurately represent energy dissipated. The final models demonstrated reduced RMSEs factors of 3.6, 1.1 and 9.5 smaller than the linear fits for anterior-posterior shear, mediolateral shear and axial rotation respectively.

These nonlinear viscoelastic models exhibit significantly increased qualities of fit to spinal load-displacement behaviour when compared to linear approximations. Furthermore, they have the advantage of solution parameters which are directly linked to physical elements: springs and dampers. The results from this study could be instrumental in improving the design of DRDs as a mechanism for treating LBP.

The most important determinant of treatment of malleolar fractures is stability. Stable fractures have an intact deep deltoid ligament and do not displace with functional treatment. If the deep deltoid/medial malleolar complex is disrupted, the talus is at risk of displacement. We developed clinical criteria for potential instability and applied them to a prospective series of patients. Criteria included: a medial clear space of < 4mm; medial tenderness, bruising or swelling; a fibular fracture above the syndesmosis; a bimalleolar or trimalleolar fracture; an open fracture; a high-energy fracture mechanism. Patients with a medial clear space of < 4mm and none of these criteria were considered to have stable fractures, while those with a medial clear space of > 4mm were considered to have a displaced fracture. We studied 152 consecutive skeletally mature patients with undisplaced, potentially unstable malleolar fractures treated by the senior author between 1st January 1998 and 31st December 2007. Patients were treated in a below-knee walking cast (136 patients) or a functional ankle brace (16 patients) for six weeks. Weight bearing was encouraged throughout. Weight bearing radiographs were obtained at one week and six weeks. Displacement was defined as talar displacement with a medial clear space > 4mm. Demographic, clinical and radiological data were collected prospectively. There were 88 male and 64 female patients, with a median age of 43 years. Criteria for possible instability were: medial tenderness, 115 patients; proximal fibular fracture, 29 patients; bimalleolar fracture, 17 patients; other criteria, 15 patients. Three fractures displaced (risk of displacement 2.0%, 95% CI 0.4–5.7%). All displaced within the first week and were treated by open reduction and internal fixation. One bimalleolar fracture developed a symptomatic medial malleolar non-union which was treated by percutaneous screw fixation (risk of non-union 5.9%, 95% CI 0.1%–28.7%). All the other fractures achieved clinical union by 8 weeks

Aim. To delineate which of four common and easily constructed Ilizarov frame configurations is best at resisting shear displacement. Methods. Four Ilizarov frames were constructed on Sawbones™ Tibiae taking into account soft tissue and neuro-vascular limitations in frame design. The designs consisted of a standard all wire frame, an opposing olive wire standard frame, a perpendicular trans-fracture opposing olive wire frame and a perpendicular half pin frame. These were tested over three cycles in compression on a load-testing machine with movement in the plane of the fracture measured using a clip gauge. Each frame was tested to the maximum displacement of the clip gauge or a total single cycle compressive load of 700N, whichever limit occurred first. Results. The perpendicular trans-fracture olive wire frame showed the least displacement in shear. The half pin frame, followed by the opposing olive standard frame and finally the all wire frame were least stable to shear displacement. Conclusion. For this fracture pattern, this study recommends the use of the perpendicular trans-fracture olive wire frame. Further investigation of immediate post-operative limb loading in patients will allow practical application of this data. Further frame motion analysis and bending analysis will allow validation of these results and allow for future frame design. The next steps in this project involve validation against FE Analysis in order to create a design software to allow mechanical templating of frame designs pre-operatively

Purpose. The purpose of this study was to assess the biomechanical stability of the a total ankle arthroplasty system using longitudinal migration (LM) and inducible displacement (ID) measures. This study is the first study of its kind to assess total ankle arthroplasty (TAA) implant micromotion using model-based radiostereometric analysis (MBRSA). Method. Twenty patients underwent TAA that implanted the Mobility(TM) (DePuy, Warsaw IN). The mean (SD) age was 60.4 (12.5) and BMI was 29.1 (2.8) kg/m. 2. One surgeon performed all surgeries. All patients included in this study had given informed consent. Capital Health Research Ethics Board had approved this study. Uniplanar medial-lateral RSA X-ray exams were taken postop (double exam), at six wk, three mth, six mth, one yr and two yr followup times using a supine, unloaded position. Standing medial-lateral exams were taken at three mth, six mth, one yr and two yr followup intervals. LM and ID micromotions were assessed using Model-based RSA 3.2 software (Medis specials, Leiden, The Netherlands). Implant micromotions (x, y, z, Rx, Ry, Rz, MTPM) were determined and assessed for each subject using model-based pose estimation, and the implant-based coordinate system. The Elementary Geometric Shapes module from the Model-based RSA 3.2 software was used to assess the micromotion of the tibial component spherical tip due to implant symmetry. Results. The median (range) maximum total point motion (MTPM) for the implants at 2 year followup were 1.23 mm (0.39–1.95 mm) for the talar implant and 0.96 mm (0.17–2.28 mm) for the spherical tip of the tibia implant. Generally for each subject and implant component, the slopes of the migration curves decreased over time. The talar and tibial implants mean LM showed initial subsidence in the y-direction (migration into the bone) followed by stabilization patterns at one year followup. The median (range) of two year MTPM ID for the talar component was 0.39 (0.27–1.06) mm. At the one year and two year followup times the ID were almost all below the detection limit of 0.85 mm. The highest measured displacement for any one talar component at either of these times was 1.06 mm. Hence, the implant was displaced at least 0.21 mm under loading. The median (range) of one year and two year MTPM ID for the tibial component spherical tip was 0.08 (0.03–0.19) mm. The tibial component spherical tip demonstrates no ID in terms of MTPM greater than the 0.22 mm detection limit. Conclusion. The implant subsides directly into the bone in the line of primary loading during standing or walking. For most of the patients the two year LM for the Mobility(TM) demonstrates a typical subsidence-stabilization behaviour seen in many RSA studies of orthopaedic implants. Based on the results of this study the Mobility(TM) components show no measurable ID. This is the first study of its kind internationally for total ankle arthroplasty and offers novel insight into the need for prosthetic design change

Introduction. The strength of the Scarf osteotomy has been compared to that of other metatarsal osteotomies, but the effect of increasing the amount of displacement is unknown. The purpose of this study was to determine whether increasing offset adversly affects the strength of the Scarf osteotomy. Methods. Seven pairs of freah frozen cadaveric feet were tested. Specimens in Group 1 underwent Scarf osteotomy with displacement of one third the mid shaft diameter. Specimens in Group 2 were offset two thirds the midshaft diameter. All osteotomies were fixed using two Barouk screws. Each specimen was tested in cantilever bending using a servohydraulic testing machine. Results. There was no statistically significant difference in strength or stiffness between the two groups. Mean strength was 75.2 N ± 16.8 for Group 1 and 64.8 N ± 28.7 for Group 2 (p> 0.05). Mean stiffness was 12.9 N/mm ± 5.1 for Group I and 10.2 N/mm ± 5.9 for Group 2 (p> 0.05). Discussion. All specimens failed at the proximal extent of the osteotomy. Failure did not occur by screw pullout in either Group. The proximal part of the cut is therefore the weakest part of the construct irrespective of the degree of osteotomy displacement

Materials and method. This study included 309 patients, over the age of 60 (44 men, 256 women, mean age 85.6 years) who underwent osteosynthesis using a short femoral nail(Gamma)for femoral intertrochanteric fractures. The new reduction classification was defined, in AP view by the degree of contact between the medial cortex of the proximal fragment and that of the medial cortex of the distal fragment. The classification in AP view is divided into three Types: Anatomical Type, Medial Type, and Lateral Type. As for the ML view was defined based on the degree of anterior cortex contact between proximal and distal fragment, was divided also into Anatomical Type, Intramedullary Type, and Extramedullary Type. We assessed lag screw sliding amount at 2 weeks period after surgery as the post-operative displacement. Results. The sliding at 2 weeks was in AP Anatomical Type 3.7mm, in Medial Type 3.2mm and in Lateral Type 9.4mm. The sliding in the Lateral Type was much greater than those of Anatomical Type and Medial Type (Significant p-value, p=0.01, 0.01). Likewise, in the ML view, Anatomical Type 3.0mm, Intramedullary Type 6.2mm and Extramedullary Type 4.7mm respectively. There was a significant difference between ML Anatomical Type and Intramedullary Type(p=0.01). Conclusion. The AP Lateral Type and the ML intramedullary Type were the most post-operative displacement. A new reduction classification could be useful to assist in the prediction of post-operation displacement

The use of percutaneous Kirschner wires [K-wires] and plaster is a popular method of treatment for displaced distal radius fracture. However, multi-database electronic literature review reveals unsurprisingly different views regarding their use. From August 2002 till June 2004, 280 distal radial fractures were admitted to our orthopaedic department. They were recorded prospectively in the departmental trauma admissions database. We studied the 87 cases treated with the K-wires and plaster technique. They were classified according to the AO classification system. The mean patient age was 53 [5-88] years. The mean delay before surgery was 7 [0-24] days. We studied the complications reported by the attending orthopaedic surgical team. 48 out of 87 patients [55.1%] were reported to have complications. We analysed the displacement and the pin tract infection, as they were the main reported complications. 28 out of 87 patients [32%] had displacement [9 had further surgery to correct the displacement, 19 did not have any further surgery as the displacement was accepted]. 11 out of 87 patients [12.6%] had pin tract infection [7 needed early removals of the K-wires and systematic treatment]. Further analysis showed no statistically significant relation between the complications rate and the age of the patients, the delay before surgery or the type of the fractures. We demonstrate a considerable high displacement and infection rate with the use of K-wires and plaster technique for fixation of distal fracture irrespective of the age of the patients, the delay before surgery or the fracture classification. There are other methods for fixation of the distal radial fracture with proven less morbidity which should be considered

Purpose: Re-establishment of correct patellofemoral kinetics is a major challenge in patients with major dislocation of the patella. Several factors affect the position of the patella, rotation of the prosthetic components, lateral section of the patella, and …perhaps…surgical access. Material and methods: Between 1994 and 1999, 26 knees with major dislocation of the patella were treated by the same operator with total knee arthroplasty (TKA) using a Cedior (Sulzer) implant. The operative technique was the same for all patients with the exception of the surgical access. For group 1 knees (n=13) a medial access was used (medial parapellar approach, 2 lateral patellar sections). For group 2 knees (n=13) a lateral access was used (lateral parapatellar approach lifting the anterior tibial tendon and refixing it after the procedure with systematic lateral fixation of the patella). Patellar tilt and lateral displacement and the patellar index (PI) (distance using head of the fibula as the fixed point) were the main judgement criteria. Student’s t test was used for statistical analysis. The two groups were comparable for: preoperative axial deviation (176.8±6.45°), lateral displacement (8.65±3.74 mm), and PI (0.789±0.166), and postoperative position of the femorotibial implants. Results: Patellar displacement persisted in one knee in group 1 requiring a new prosthesis. Anterior impaction of the tibial piece in one knee in group 2 did not require reoperation. Radiographically, lateral displacement was minimal in both groups (0.692 and 0 mm in groups 1 and 2) (p=0.17). Residual postoperative tilt was +3.8° in group 1 and −3.3° in group 2 (p=0.06). PI was 0.859 in group 1 and 0.956 in group 2 (p=0.24). In group 2, the postoperative PI (0.956±0.231) was not changed from the preoperative PI (0.831±0.152) an expression of the absence of ascension of the anterior tibial tendon (p =0.1). Dicussion: Lateral displacement of the patella was entirely corrected in both groups. Unlike the lateral access, medial access, even with lateral section of the patella, did not correct for the tilt. Raising the anterior tibial tendon did not in our experience have any iatrogenic effect in itself. Irrespective of the femorotibial axis, lateral access for degenerative knees with major dislocation of the patella appears to be the best approach for implantation of total knee arthroplasty

Knee injuries in cyclists are often thought to result from an imbalance of load during the cycling motion as a consequence of inappropriate bike set-up. Recently, it has been postulated that incorrect foot positioning may be a significant factor in lower limb injury and poor cycling performance. The purpose of this study is to assess the effect of changing the foot position at the shoe-pedal interface on Vastus Medialis (VM) and Vastus Lateralis (VL) activity (mean and mean peak), knee angle and knee displacement. Maximum power tests were completed on a first visit, with data collection on a second visit recorded at 60% of the subjects maximum. Video footage and surface electromyography (SEMG) from VM and VL muscles was obtained. Data was recorded over 10 crank cycles in 3 experimental conditions; neutral, 10 degrees inversion and 10 degrees eversion using Ethylene Vinyl Acetate (EVA) wedges fitted between the cyclists shoe and the shoe cleat. Raw data (mean SEMG, mean peak SEMG) was obtained using Noraxon and SiliconCOACH measured knee angle and knee displacement. Data was analyzed using Friedmans test with appropriate post hoc tests. 12 male subjects (range 26-45, mean 35.9 years) completed the study. Mean and mean peak SEMG data showed no significant differences between the 3 experimental conditions for VM and VL. VM:VL ratios from raw mean SEMG data demonstrated a decrease in synchronicity in inversion and eversion compared to neutral. Pronators demonstrated most synchronicity in inversion and least synchronicity in eversion. There were statistically significant differences in knee angle and knee displacement between neutral, inversion and eversion (p<0.05). Inversion promoted smaller knee valgus angles and greater knee displacement from the bike. Eversion promoted larger knee valgus angles and a smaller displacement from the bike. By altering the foot position to either 10 degrees inversion or 10 degrees eversion, knee angle and knee displacement can be significantly influenced. Clinically, subjects who foot type is classified as pronating may benefit from some degree of forefoot inversion posting. Further research on subjects with knee pain needs to be undertaken