Aims. There are concerns regarding nail/medullary canal mismatch and initial stability after cephalomedullary nailing in unstable pertrochanteric fractures. This study aimed to investigate the effect of an additional anteroposterior blocking screw on fixation stability in unstable pertrochanteric fracture models with a nail/medullary canal mismatch after short cephalomedullary nail (CMN) fixation. Methods. Eight finite element models (FEMs), comprising four different femoral diameters, with and without blocking screws, were constructed, and unstable intertrochanteric fractures fixed with short CMNs were reproduced in all FEMs. Micromotions of distal shaft fragment related to proximal fragment, and stress concentrations at the nail construct were measured. Results. Micromotions in FEMs without a blocking screw significantly increased as nail/medullary canal mismatch increased, but were similar between FEMs with a blocking screw regardless of mismatch. Stress concentration at the nail construct was observed at the junction of the nail body and lag screw in all FEMs, and increased as nail/medullary canal mismatch increased, regardless of blocking screws. Mean stresses over regions of interest in FEMs with a blocking screw were much lower than regions of interest in those without. Mean stresses in FEMs with a blocking screw were lower than the yield strength, yet mean stresses in FEMs without blocking screws having 8 mm and 10 mm mismatch exceeded the yield strength. All mean stresses at distal locking screws were less than the yield strength. Conclusion. Using an additional anteroposterior blocking screw may be a simple and effective method to enhance fixation stability in unstable pertrochanteric fractures with a large nail/medullary canal mismatch due to osteoporosis. Cite this article: Bone Joint Res 2022;11(3):152–161

Purpose. Intramedullary fixation of clavicle fractures requires an adequate medullary canal to accommodate the fixation device used. This computer tomography anatomical study of the clavicle and its medullary canal describes its general anatomy and provides the incidence of anatomical variations of the medullary canal that complicates intramedullary fixation of midshaft fractures. Methods. Four hundred and eighteen clavicles in 209 patients were examined using computer tomography imaging. The length and curvatures of the clavicles were measured as well as the height and width of the clavicle and its canal at various pre-determined points. The start and end of the medullary canal from the sternal and acromial ends of the clavicle were determined. The data was grouped according to age, gender and lateralization. Results. The average length of the clavicle was 151.15mm with the average sternal and acromial curvature being 146° and 133° respectively. The medullary canal starts on average 6.59mm from the sternal end and ends 19.56mm from the acromial end with the average height and width of the canal at the middle third being 5.61mm and 6.63mm respectively. Conclusion. The medullary canal of the clavicle is large enough to accommodate commonly used intramedullary devices in the majority of cases. The medullary canal extends far enough medially and laterally to ensure that an intramedullary device can be passed far enough medially and laterally past the fracture site to ensure stable fixation in most middle third clavicle fractures. An alternative surgical option should be available in theatre when treating females as the medullary canal is too small to pass an intramedullary device past the fracture site on rare occasions. Fractures located within 40mm of the lateral or medial ends of the clavicle should not be treated by intramedullary fixation as adequate stability is unlikely to be achieved. MULTIPLE DISCLOSURES

Intramedullary infection is a challenging problem and management usually includes removal of the infected hardware and reaming of the medullary canal. The purpose of this study is to describe a new technique for canal debridement and evaluate its efficacy in the treatment of posttraumatic osteomyelitis of the tibia and femur. This retrospective study included 11 patients (10 male and 1 female, mean age: 42 years) with posttraumatic osteomyelitis of the tibia (n=8) or femur (n=3). Surgical treatment consisted of debridement, implant removal, and reaming of the medullary canal with the RIA (Reamer Irrigator Aspirator) device. All procedures were performed by a single surgeon with a standardised technique. Reaming of the canal was performed with one pass of the RIA. Following reaming, the RIA was used for irrigation of the medullary canal with 10 liters of fluid. At a mean follow-up time of 9 months (6 to 13 months) there was no recurrence of osteomyelitis. Complications included one partial loss of a flap, one refracture of a tibia following an auto versus pedestrian accident, and external fixator pin tract infections in one patient. The RIA device allows for reaming under simultaneous irrigation and aspiration, which may minimise the residual amount of infected tissue in the medullary canal. The disposable reamer head is always sharp, in contrast to standard reamers, which may reduce the thermal effects of reaming on the adjacent bone. In addition, the RIA allows delivery of fluid throughout the length of the medullary canal, thus facilitating irrigation. The RIA device is useful alternative for debridement of intramedullary infections of the tibia and femur

Using an established canine model of fat embolization, the effect of temporary mechanical blockade of embolic load during medullary canal pressurization was studied. Haemodynamic measurements, echocardiography and postmortem histomorphometry were used as outcome measures. There was statistically significant difference between the filter and the control groups, when the pulmonary vascular resistance, the percentage area of lungs occupied by fat and the percentage of pulmonary vasculature occupied by fat were compared. We have shown that mechanical blockade by a filter does stop the adverse effect on the lungs during canal pressurization. Acute intramedullary stabilization of femoral fractures in multiply injured patients still remains controversial. Intravasation of medullary fat has been suspected to trigger ARDS. This study investigates the effect of a filter placed into the ipsilateral common iliac vein during medullary canal pressurization. Using an established canine model, twelve mongrel dogs were randomized into two groups. A special filter was inserted percutaneously into the left common iliac vein in half the dogs where as the other half served as controls. In all dogs, the left femora and tibiae were pressurized by injection of bone cement and insertion of intramedullary rods. Hemodynamic measurements and echocardiography images were recorded continuously. After sacrifice, the lungs were harvested for analysis. The mean pulmonary artery pressure at three minutes of pressurization was 12 mm of Hg in the filter group and 28mm of Hg in the control group. The pulmonary vascular resistance in the control group was increased from the 3. rd. minute of pressurization throughout the experiment. This was statistically significant when compared with the baseline. There was no such change seen in the filter group. Transesophageal echocardiography showed less embolic shower in the filter group and histomorphometry demonstrated statistically signifant difference, when the percentage area of lungs and the percentage of pulmonary vasculature occupied by fat in the filter group as compared to the control group. This canine study has demonstrated that mechanical blockade by a venous filters can significantly reduce the embolic load on the lungs during canal pressurization

Introduction and Aims: Acute intramedullary stabilisation of femoral shaft fractures in multiply injured patients remains controversial. Intravasation of medullary fat during nailing has been suspected to trigger ARDS. This study investigates the effect of a filter placed into the ipsilateral common iliac vein during medullary canal pressurisation in a canine experiment. Method: Using an established model, 12 mongrel dogs were randomised into two groups. Under general anesthesia, cannulations were performed to measure left and right-sided pressures. Transoesophageal echocardiography was performed in all dogs. A special ‘TRAP ‘filter was inserted percutaneously into the left common iliac vein in six dogs, whereas the other six served as controls. In all dogs, the left femora and tibiae were then pressurised by injection of bone cement and insertion of intramedullary rods. Hemodynamic measurements and echocardiography images were recorded continuously. After one hour, the animals were sacrificed and the lungs were harvested for histomorphommetric analysis. Results: The mean pulmonary artery pressure at three minutes of pressurisation was 12mm of Hg in the filter group and 28mm of Hg in the control group. There was increase in the peak systolic pulmonary artery pressure and the right ventricular pressure after canal pressurisation in the control group, whereas no such changes were observed in the filter groups. The pulmonary vascular resistance as denoted by the difference between the mean pulmonary artery pressure and the end diastolic left ventricular pressure increased significantly (p< 0.05) at three, five, 10,15 and 30 minutes after pressurisation in the control group when compared to the baseline value. In the filter group, the pulmonary vascular resistance increased only slightly after pressurisation. Transesophageal echocardiography images were analysed by a blinded echocardiologist. There was evidence of moderate to severe embolisation in the control group with detection of large echogenic particles. In comparison, there was mild grade of embolisation in the filter group. Histological analysis showed statistically significant difference between the two groups, when comparison of the percentage of area of lung tissue occupied by fat, the percentage of pulmonary vasculature occupied by fat and the maximum size of the embolus were made (p< 0.05). Conclusion: This study has conclusively demonstrated that mechanical blockade by venous filters prior to medullary canal pressurisation, significantly reduces the embolic load and its effect on the lungs. A retrievable filter with a system to remove the accumulated marrow content is being developed for use in high-risk patients

Introduction: Early stabilization of the skeleton in multiply injured patients has shown to reduce mortality and chest morbidity. Reamed intramedullary nailing is the current method of choice for stablizing femoral and tibial shaft fracture. However several investigators have highlighted the adverse effect of early reamed nailing in polytrauma patients. Intravasation of medullary fat during canal pressurizaton has been suspected to produce a ‘second hit’ and trigger pneumonia and ARDS. The objective of this study is to investigate the effect of a filter placed into the ipsilateral common iliac vein during medullary canal pressurization. Methods: Using an established model of fat embolization, twelve mongrel dogs were randomized into two groups. Under general anaesthesia, cannulations of carotids and jugular veins and transesophageal echo-cardiography were performed in all animals. Under fluoroscopy control, a special filter was inserted percutaneously into the left common iliac vein in half the animals, where as the other half served as controls. In all dogs, the left knee was exposed; the femor and tiiba were sequentially reamed and then pressurized by injection of bone cement and insertion of intramedullary rods. Hemodynamic measurements and trans-esophageal echocardiography images were recorded continuously during the surgical procedure. After 45 minutes from pressurization, the dogs were sacrificed and the lungs and kidneys were harvested and fixed for histological analysis. Results: There was significant difference noticed in the right-sided pressures and oxygen tension between the filter and the control groups. The mean pulmonary artery pressure at 3 minutes of pressurization was 12mm of Hg in the filter group and 28mm of Hg in the control group. Transesophageal echocardiography showed less embolic shower in the filter group and also lesser dilatation of right ventricles. Histomorphometry with special staining demonstrated much less proportion of lungs to be occupied by fat in the filter group as compared to the control group. Discussion and Conclusion: This canine study has demonstrated that mechanical blockade by a venous filter can significantly reduce the emobilic load on the lungs in an established model of fat embolization. A suitable filter with suction system is being designed for possible use in high-risk patients

It is suggested that there is a group of cases of congenital angulation of tubular bones in which the lesion is a defect of ossification of the primary cartilaginous anlage and in which neurofibromatosis is not implicated. It appears that in this group the prognosis with regard to the resolution of deformity and the prevention of pseudarthrosis with conservative treatment or relatively simple surgical procedures is better than that in the neurofibromatous type.

Purpose: The purpose of this study is to evaluate the hemodynamic and pulmonary effects of intramedullary nailing with a removable filter placed into the common iliac vein.

Methods: Under general anaesthesia, a collapsible filter was inserted into the left common iliac vein in eight dogs and compared to a control group from a previous study. The left femora and tibiae were then pressurized by injection of bone cement and the insertion of intramedullary rods. Echocardiographic images and hemodynamic measurements including arterial blood gas, cardiac output, left atrial, right atrial, pulmonary arterial, and aortic pressure were recorded as baseline measurements and at 1, 5 and 15 minutes after medullary-canal pressurization. After fifteen minutes of pressurization the filter debris was evacuated, the samples sent for analysis and the filter was collapsed and removed. The dog’s hemodynamics were then monitored for a further fifteen minutes. The animals were killed and the lungs were harvested for histomorphometric analysis.

Results: Full hemodynamic and histomorphometric results of the lung tissue and debris collected from the evacuated filters are still pending at the time of this submission however initial findings indicate that the filter prevented an immediate increase in mean pulmonary artery pressure after canal pressurization. No large embolic event was visualized in any of the filtered dogs. In contrast, all animals in the control group demonstrated moderate-to-severe echogenic response with intense showering of echogenic material, including large embolic masses. Removal of the filter was safe and repeatable.

Conclusions: This experiment has shown that proximal venous blockade by means of a removable filter was able to reduce the size and the quantity of the embolic load on the lungs and the filter could be safely collapsed and removed after suctioning of the debris. High rates of embolization causing increased morbidity and mortality after intramedullary stabilization of pathological fractures and of traumatic fractures with concomitant lung injury have been reported. Prophylactic insertion of a removable temporary filter in this high-risk group prior to reamed intramedullary nailing may be beneficial.

Funding : Other Education Grant

Funding Parties : Synthes Canada

Background. The purpose of this study was to investigate the morphology characteristic of proximal femur of Chinese people. 170 healthy Southern Chinese hips being measured using 3D computer tomographic, in order to improve prosthesis design and preoperation plan of total hip arthroplasty. Methods. This study measured proximal femoral geometry in 85 healthy Southern Chinese, included 39 women (78 hips) and 46 men (92 hips) (mean age: 33.9 y, mean height: 164.7 cm, mean weight 59.9 kg). Medullary canal morphology measurements, include: the position of isthmus, medial-lateral(ML) and anteroposterior(AP) medullary canal diameter of isthmus and 20 mm, 10 mm, 0 mm, −20 mm, −160 mm, −200 mm upon less trochanter(LT) (medullary canal height, MCH), canal flare index(CFI), aspect ratio(ML/AP), epiphysis-shaft angel (ES angel) (a posterior bow in the metapysis in lateral view). Exterior morphology measurements include: femoral head offset, ML and UD diameter, femoral head position(FHP) from LT, height of the femoral head center from the tip of the great trochanter(GT)(FHCH), femoral neck and head anteversion angle, femoral neck-shaft angle, neck length, neck width, intertrochanteric length (Fig 1, Fig 2). And then we use student's t–test to compare means, linear regression and correlation to analysis these data's relationship, p value <0.05 indicated a significant effect. Results. Males had a larger diameter of medullary canal than females (Fig3). The isthmus position is 117.69±11.95 VS 111.14±13.01 mm (male VS female) (p=0.070) below less trochanter, and it's ML diameter is 9.57±1.52 VS 8.88±1.80 mm (p=0.151), AP diameter is 11.85±2.68 VS 10.53±2.49 mm (p=0.073). The mean medullary canal aspect ratio is 1.38±0.20, 1.30±0.12, 1.15±0.13, 1.03±0.09, 0.84±0.11, 0.87±.011 and 1.04±0.17 respectively at 20 mm, 10 mm, 0 mm, −20 mm, isthmus, −160 mm, −200 mm upon less trochanter. The medullary canal diameter were positively correlated to MCH (R=0.793, p=0.000 VS R=0.790, p=0.000) (ML VS AP). The ES angle is 156.78±4.29 VS 157.90±4.90 degree (p=0.395) (male VS female). The femoral head offset is 39.14±3.87 VS 35.86±3.68 mm (p=0.003), femoral neck, head and comprehensive anteversion angle is 18.34±8.07 VS 17.9±10.64 degree (p=0.872), −2.61±6.47 VS −2.36±5.55 degree (p=0.881) and 15.73±7.26 VS 15.54±8.54 degree (p=0.934). FHP is 51.67±7.82 VS 45.37±5.59 mm (p=0.001), FHCH is −6.77±5.58 VS −6.13±4.87 mm (p=0.665), femoral head diameter is (ML: 43.94±2.62 VS 39.25±2.66 mm (p=0.000), UD: 45.16±1.96 VS 41.26±2.23 mm (p=0.000)). Femoral neck-shaft is 130.10±4.57 VS 130.83±6.40 degree (p=0.652), femoral neck length and width is 21.84±4.87 VS 20.69±3.41 mm (p=0.322) and 34.75±2.26 VS 31.80±2.63 mm (p=0.000), femoral intertrochanteric length is 68.11±4.72 VS 61.27±5.04 mm (p=0.000), most of these dimensions were positively correlated to height. Conclusion. Males had a larger medullary canal than females, the long diameter of medullary canal is transverse at proximal femoral, and it gradually become longitudinal when move to isthmus then become transverse again below isthmus, this may offer valuable revelation for our anti-rotation design and better distal fixation. The medullary canal diameter were positively correlated to MCH. 71% (121 hips) femoral heads had a retroversion angle compare to femoral neck. The femoral head rotation center is below the tip of the GT rather than on the same level that may suggested a shorter neck implants for Southern Chinese patients

Cutting rodent's bone ends and irrigation of the medullary canal is the common method used for cells collection in allogenic transplantation, however it does not yield sufficient cells for autologous transplantation. The aim of this experiment was to establish and validate a method for bone marrow collection for autologous MSCs transplantation. Two collection methods were examined: 1) Transection of the bone ends and irrigation of the medullary canal, 2) Trephining of the bone with a hypodermic needle without aspiration. Then cell harvesting was compared in the idealised laboratory situation and under simulated surgery. First, two lower limbs were harvested from the same rat cadaver for comparison, bone marrow in one limb was collected by cutting the femoral head and the distal tibia and irrigation of the canal through drilled holes at the distal end of the femur and proximal end of the tibia. Other limb, hypodermic needle was used as a trephining tool into the medullary canal multiple times without applying negative pressure and rinsed from inside and outside. Second, bone marrow was harvested from another rat's cadaver in the surgery room to simulate the conditions needed for autologous transplantation. The number of cells from irrigation method was 1.28*106 cells, whereas that from trephining method reached 17*106. The number cells from the bone marrow harvested in the surgery room was found 29.6*106. We report a novel technique for harvesting cells for autologous cell therapy from only one limb. A significantly larger number of cells from bone marrow could be collected using the needle trephining method. There is no negative effect on the viability of cells after bone marrow harvesting in the surgery room

Aims. It has been hypothesized that proximal radial neck resorption (PRNR) following press-fit radial head arthroplasty (RHA) is due to stress-shielding. We compared two different press-fit stems by means of radiographs to investigate whether the shape and size of the stems are correlated with the degree of PRNR. Methods. The radiographs of 52 RHAs were analyzed both at 14 days postoperatively and after two years. A cylindrical stem and a conical stem were implanted in 22 patients (group 1) and 30 patients (group 2), respectively. The PRNR was measured in the four quadrants of the radial neck and the degree of stem filling was calculated by analyzing the ratio between the prosthetic stem diameter (PSD) and the medullary canal diameter (MCD) at the proximal portion of the stem (level A), halfway along the stem length (level B), and distally at the stem tip (level C). Results. Overall, 50 of the 52 patients displayed PRNR. The mean PRNR observed was 3.9 mm (0 to 7.4). The degree of endomedullary stem filling at levels A, B, and C was 96%, 90%, and 68% in group 1, and 96%, 72%, and 57%, in group 2, with differences being significant at levels B (p < 0.001) and C (p < 0.001). No significant correlations emerged between the severity of PRNR and the three stem/canal ratios either within each group or between the groups. Conclusion. PRNR in press-fit RHA appears to be independent of the shape and size of the stems. Other causes besides stem design should be investigated to explain completely this phenomenon. Cite this article: Bone Joint J 2021;103-B(3):530–535

Objective. To three-dimensionally reconstruct the proximal femur of DDH (Developmental dysplasia of the hip) and measure the related anatomic parameters, so that we could have a further understanding of the morphological variation of the proximal femur of DDH, which would help in the preoperative planning and prosthesis design specific for DDH. Methods. From Jan.2012 to Dec.2014, 38 patients (47 hips) of DDH were admitted and 30 volunteers (30 hips) were selected as controls. All hips from both groups were examined by CT scan and radiographs. The Crowe classification method was applied. The CT data were imported into Mimics 17.0. The three-dimensional models of the proximal femur were then reconstructed, and the following parameters were measured: neck-shaft angle, neck length, offset, height of the centre of femoral head, height of the isthmus, height of greater trochanter, the medullary canal diameter of isthmus(Di), the medullary canal diameter 10mm above the apex of the lesser trochanter(DT+10), the medullary canal diameter 20mm below the apex of the lesser trochanter(DT-20), and then DT+10/Di, DT-20/Di and DT+10/DT-20 were calculated. Results. There is no significant difference in neck-shaft angle between Crowe I-III DDH and the control group, while the neck-shaft angle is much smaller in Crowe IV DDH. The neck length of Crowe IV DDH is much smaller than those of Crowe I-III DDH. As for Di there is neither significant difference between Crowe I DDH and the control group, nor significant difference between CroweII-III and Crowe IV, but the difference is significant between the first two groups and the latter two groups. DT+10/DT-20 and the offset have no significant difference between the control group and DDH groups. DT-20, DT+10, DT+10/Di and DT-20/Di are much smaller in Crowe IV DDH than that in Crowe I-III and the control groups. Height of greater trochanter in Crowe IV is larger than those in Crowe I-III and the control group. Height of the centre of femoral head in Crowe IV DDH is smaller than those in Crowe I-III DDH and the control group. The height of the isthmus in Crowe IV is much smaller than those in Crowe I-III DDH and the control group. Conclusion. The neck-shaft angle in DDH groups is not larger than that in the control group, while in contrast, it's much smaller in Crowe IV DDH than that in the control group. Comparing to Crowe I-III DDH and the control group, Crowe IV DDH has a dramatic change in the intramedullary and extramedullary parameters. The isthmus and the great trochanter are higher and there is apparent narrowing of the medullary canal around the level of the lesser trochanter

Revision of infected TKA is one of the most challenging operation as the surgeon should achieve two goals, ie eradication of infection and restoration of function. For the eradication of infection, a minimum of two operations are needed in most of cases. First stage of revision is meticulous debridement and insertion of antibiotic loaded cement. During arthrotomy, thick fibrous and granulation tissues which is located in the suprapatella pouch, lateral site to the patella tendon and posterior joint space should be removed so as to get better exposure, to get rid of infection source and to get better functional result. During debridement, I use highly concentrated antibiotic saline (1 gm vancomycin in 10cc saline), for irrigation of the operation field. I also pack the opening of the medullary canal so as to prevent the debris from entering into the medullary canal. I use antibiotics with the ratio of 1:3. To reduce the dead space in the medullary canal I insert a dowel shaped antibiotic loaded cement spacer made from one pack of cement and fill the medullary canal. Thereafter two packs of cement are used to make a block to fill the gap between femur and tibia. The cement block should be large enough to cover the distal femur and proximal tibia so as not to cause bone defect and knee dislocation during walking. After first stage of operation, antibiotics are administered for 4∼8 wks until the CRP levels become normalized and clinical findings show no sign of infection. The 2. nd. stage of operation is planned when clinical and laboratory signs of infection subside. The decision whether to reimplant the prosthesis or not is based on the operation findings and polymorphonuclear cell count on frozen section. However operation findings are considered more important than the frozen section results for reimplantation. If operative findings are clean, I do reimplanation even though the polymorphonuclear cell count is more than 5 on high power field(hpf) on frozen section. I have adopted numbering system to take specimen. Number 1 is specimen from suprapatella pouch, No 2 is that from gap between the femur and tibia, No 3 is that from femoral intramedullary canal, No 4 is that from tibial intramedullary canal, and No 5 is that from most unhealthy site. In a retrospective analysis of 16 cases which received reimplantation despite of the prescence of more than five polymorphonuclear cells on intra-operative frozen sections, none of the cases had recurrence of infection at a final follow up of 2 years. The femoral medullary canal was the most prevalent site for higher polymorphonuclear cell count. In conclusion, indication is the first step for successful reimplantion. Two stage revision is recommended and meticulous debridement is utmost important in first stage operation. Block type antibiotic loaded cement is sufficient for a good result. Clinical, laboratory and operative findings are more important than polymorphonuclear cell count on frozen section to decide reimplantation. I propose numbering system of the specimen site for frozen section, just as in tumor surgery

Aims. Osteopetrosis (OP) is a rare hereditary disease that causes reduced bone resorption and increased bone density as a result of osteoclastic function defect. Our aim is to review the difficulties, mid-term follow-up results, and literature encountered during the treatment of OP. Methods. This is a retrospective and observational study containing data from nine patients with a mean age of 14.1 years (9 to 25; three female, six male) with OP who were treated in our hospital between April 2008 and October 2018 with 20 surgical procedures due to 17 different fractures. Patient data included age, sex, operating time, length of stay, genetic type of the disease, previous surgery, fractures, complications, and comorbidity. Results. The mean follow-up period was 92.5 months (25 to 140). Bony union was observed in all of our patients. Osteomyelitis developed in two patients with femoral shaft fractures, and two patients had peri-implant stress fractures. Conclusion. Treatment of fractures in OP patients is difficult, healing is protracted, and the risk of postoperative infection is high. In children and young adults with OP who have open medullary canal and the epiphyses are not closed, fractures can be treated with surgical techniques such as intramedullary titanium elastic nail (TENS) technique or fixation with Kirschner (K)-wire. Cite this article: Bone Joint J 2020;102-B(8):1082–1087

In the vast majority of patients, the anatomical and mechanical axes of the tibia in the coronal plane are widely accepted to be equivalent. This philosophy guides the design and placement of orthopaedic implants within the tibia and in both the knee and ankle joints. However, the presence of coronal tibial bowing may result in a difference between these two axes and hence cause suboptimal placement of implanted prostheses. Although the prevalence of tibial bowing in adults has been reported in Asian populations, to date no exploration of this phenomenon in a Western population has been conducted. The aim of this study was to quantify the prevalence of coronal tibial bowing in a Western population. This was an observational retrospective cohort study using anteroposterior long leg radiographs collected prior to total knee arthroplasty in our high volume arthroplasty unit. Radiographs were reviewed using a Picture Archiving and Communication System. Using a technique previously described in the literature for assessment of tibial bowing, two lines were drawn, each one third of the length of the tibia. The first line was drawn between the tibial spines and the centre of the proximal third of the tibial medullary canal. The second was drawn from the midpoint of the talar dome to the centre of the distal third of the tibial medullary canal. The angle subtended by these two lines was used to determine the presence of bowing. Bowing was deemed significant if more than two degrees. The position of the apex of the bow determined whether it was medial or lateral. Measurements were conducted by a single observer and 10% of measurements were repeated by the same observer and also by two separate observers to allow calculation of intraclass correlation coefficients (ICCs). A total of 975 radiographs consecutively performed in the calendar years 2015–16 were reviewed, 485 of the left leg and 490 of the right. In total 399 (40.9%) tibiae were deemed to have bowing more than two degrees. 232 (23.8%) tibiae were bowed medially and 167 (17.1%) were bowed laterally. The mean bowing angle was 3.51° (s.d. 1.24°) medially and 3.52° (s.d. 1.33°) laterally. Twenty-three patients in each group (9.9% medial/13.7% lateral) were bowed more than five degrees. The distribution of bowing angles followed a normal distribution, with the maximal angle observed 10.45° medially and 9.74° laterally. An intraobserver ICC of 0.97 and a mean interobserver ICC of 0.77 were calculated, indicating excellent reliability. This is the first study reporting the prevalence of tibial bowing in a Western population. In a significant proportion of our sample, there was divergence between the anatomical and mechanical axes of the tibia. This finding has implications for both the design and implantation of orthopaedic prostheses, particularly in total knee arthroplasty. Further research is necessary to investigate whether prosthetic implantation based on the mechanical axis in bowed tibias results in suboptimal implant placement and adverse clinical outcomes

To quantify bone-nail fit in response to varying nail placements by entry point translation in straight antegrade humeral nailing using three-dimensional (3D) computational analysis. CT scans of ten cadaveric humeri were processed in 3D Slicer to obtain 3D models of the cortical and cancellous bone. The bone was divided into individual slices each consisting of 2% humeral length (L) with the centroid of each slice determined. To represent straight antegrade humeral nail, a rod consisting of two cylinders with diameters of 9.5mm and 8.5mm and length of 0.22L mm and 0.44L mm respectively joined at one end was modelled. The humeral head apex (surgical entry point) was translated by 1mm in both anterior-posterior and medio-lateral directions to generate eight entry points. Total nail protrusion surface area, maximum nail protrusion distance into cortical shell and top, middle, bottom deviation between nail and intramedullary cavity centre were investigated. Statistical analysis between the apex and translated entry points was conducted using paired t-test. A posterior-lateral translation was considered as the optimal entry point with minimum protrusion in comparison to the anterior-medial translation experiencing twice the level of protrusion. Statistically significant differences in cortical protrusion were found in anterior-medial and posterior-lateral directions producing increased and decreased level of protrusion respectively compared to the apex. The bottom anterior-posterior deviation distance appeared to be a key predictor of cortical breach with the distal nail being more susceptible. Furthermore, nails with anterior translation generated higher anterior-posterior deviation (>4mm) compared to posterior translation (<3mm). Aside from slight posterolateral translation of the entry point from the apex, inclusion of a distal posterior-lateral bend into current straight nail design could improve nail fitting within the curved humeral bone, potentially improving distal working length within the flat and narrow medullary canal of the distal humeral shaft

In impaction allografting, the host bone interface consists of morsellized allograft alone or as a composite with bone cement. The objective of this study was to investigate the host bone temporal changes in the interface for these two materials in a rat bone chamber model. The composite-host bone interface strength was significantly higher at three weeks and was higher than the allograft construct. Limited allograft, but extensive periosteal remodelling, was observed at three weeks. At six weeks a new medullary canal was formed and the endosteal cortex was partially absorbed. Endosteal absorption resulting in medullary canal widening may be responsible for clinically unstable stems after impaction allografting. The host bone interface after impaction allografting consists of morsellized allograft alone or as a composite with cement and it may be important for the clinical success of this procedure. The purpose of this study was to investigate the temporal changes of these interfaces in a rat bone chamber model. Bone chambers were inserted in both tibiae of thirty-three rats and tightened to the endosteal surface to create a microenvironment. One chamber was filled with allograft bone and the other with an allograft/ cement composite. After zero, three, and six weeks, the rats were euthanized, the interfaces mechanically tested and processed for histomorphometric analysis. The composite-host bone interface strength was significantly higher at three weeks and was higher than the allograft construct. Extensive periosteal remodelling was observed at three weeks. At six weeks a new medullary canal was formed and the endosteal cortex was partially absorbed. The increased interface strength of the composite-host bone interface was due to fibrous tissue attachment rather than direct bonding of the bone particles. Cortical porosity and cancellisation is known to be caused by a damaged endosteal circulation resulting in medullary canal widening and may cause clinically unstable implants. Interface strength of the composite-host bone interface was increased at three weeks through fibrous tissue attachment. A damaged endosteal circulation caused cortical porosis and cancellisation. With this rat bone chamber model a potential cause of stem subsidence after impacting allografting was identified. Funding: The George W. Bagby Research Fund. The Canadian Institutse of Health Research. The Maurice E. Müller Foundation. The Swiss Academy of Engineering Science. The Robert Mathys Foundation

Introduction. An important factor in the internal fixation of pertrochanteric fractures is the ability to maintain postoperative reduction. Excessive postoperative sliding of the lag screw or blade may result in reduction loss. We retrospectively analyzed the relationship between postoperative reduction and sliding. Methodology. From Oct. 2009 to Sept. 2011, we treated pertrochanteric fractures using J-PFNA (Synthes) and InterTAN (Smith & Nephew) in 91 cases and 82 cases, respectively. We used postoperative radiographs to classify its reduction. Fractures were classified for its interfragmentary contact using the calcar femorale as a reference on the A-P plane while using the anterior cortex as a reference on the M-L plane. Results. PFNA cases showed greater postoperative sliding than InterTAN cases. Both demonstrated greater sliding when the proximal fragment was positioned inside the medullary canal on the M-L plane than when positioned outside or anatomically. Conclusion. Although the InterTAN can maintain greater initial stability necessary for early weight-bearing, both implants demonstrate the loss of interfragmentary contact when the proximal fragment is positioned inside the medullary canal on the M-L plane resulting in greater risk of reduction loss. In order to maintain postoperative reduction, either anatomical reduction or reducing the proximal fragment outside the medullary canal is advised; no matter what type of internal fixation implants are used

Background. Cement restrictors are used for maintaining good filling and pressurization of bone cement during hip and knee arthroplasties. The limitations of certain cement restrictors include the inability to accommodate for large medullary canals particularly in revision procedures. We describe a technique using SurgicelTM (Johnson & Johnson) and SPONGOSTAN™ (Johnson & Johnson) (Fig 1) to form a cement restrictor that can accommodate for large canal diameters and provide excellent pressurisation. Technique. The technique involves the application of SPONGOSTAN™ (Johnson & Johnson) foam onto a SurgicelTM (Johnson & Johnson) mesh which is then rolled onto the SPONGOSTAN™ foam forming a uniform cylindrical structure Figs 2,3. The diameter of the restrictor can be adjusted according to the desired femoral canal diameter through increasing the thickness of the SPONGOSTAN™ (Johnson & Johnson) foam. The restrictor is then inserted into the desired position in the medullary canal where it expands uniformly creating an effective restrictor and bone plug Fig 4. Bone cement is then applied and pressurisation commenced prior to the insertion of the implant Fig5. SPONGOSTAN™ is an absorbable haemostatic sponge intended for haemostatic use by applying to a bleeding surface. It consists of a sterile, water-insoluble, malleable, porcine gelatin absorbable sponge. Surgicel ™ is an absorbable hemostatic agent composed of oxidized regenerated cellulose. It is a sterile, absorbable knitted fabric that is flexible and adheres readily to bleeding surfaces. Both products are routinely used for their haemostatic properties in various surgical disciplines. Discussion. The use of intramedullary plugs in cemented total joint arthroplasty is essential in order to achieve good filling and pressurization in hip and knee arthoplasties, traditionally, a small piece of bone or a cement restrictor may be used to plug the shaft. Distal plugs seal the femoral canal, improve fixation and prevent bone cement from leaking during delivery and pressurization. Plugging the intramedullary canal during total hip arthroplasty increases penetration of cement into cancellous bone proximal to the intramedullary plug. Numerous plug designs and materials are available ranging from non-resorbable to resorbable. Regardless of design, all restrictors should avoid intramedullary cement leakage and plug migration during cement and stem insertion to ensure adequate intramedullary pressures. In some instances the diameter of the femoral canal is too wide to accommodate a conventional cement restrictor particularly when crossing the femoral isthmus and even more so in revision procedures requiring the implantation of long stemmed cemented components. The use of the Surgicel-Spongostan haemostatic restrictor overcomes some of the limitations of a standard cement restrictors. These include the ability to bypass a narrow femoral isthmus, accommodate large femoral canals, particularly in revision procedures, and the flexibility of adjusting the restrictor to the desired diameter of the medullary canal and in effect providing a bespoke cement restrictor. This technique was used successfully in over 300 revision hip and knee procedures with no adverse effects and excellent outcomes

Introduction. We developed original KKS non-cement THA system and used clinically over 10 years. KKS means Keio Kyocera Series. This system was developed co-ordinating with Keio-University and Kyocera Company in Japan. Our concept was to make original THA system suitable for Japanese people. Osteoarthritis of the hip in Japanese people caused mainly from developmental dysplasia of the hip. So the shape of femoral medullary canal is characteristic compared with foreign patients. We analyzed the femoral medullary canal shape in typical Japanese osteoarthritis 50 cases of the hip by the use of CT scan. From the results of these analyses, we determined the optimal shape of KKS non-cement stem for Japanese patients. It has double tapered shape in distal stem shaft. Proximal taper angle of the stem is 4 degree, and distal one is 3 degree. The proximal part of stem has characteristic notch in anterior and posterior and lateral surface to tolerate rotational stability. Objectives. We evaluated long terms results (over 10 years) of KKS original stem mainly radio graphically and estimate the usefulness. Methods. We started to use porous HA coated KKS stem from 1995. From 1995 to 1998 this stem was applied for 73 cases of non-cement THA in Keio-University. Excluding 2 cases of infection and stem breakage, 55 of 71 cases could be followed over 10 years (follow-up rate: 75%). In these 55 cases, average age at THA operation was 54 (24–64) years old and mean follow-up time was 11.2 (10–13) years. Radiographic findings in 55 cases at follow-up time were evaluated, concerning about following points: stem sinking, loosening, spots-welds, calcar resorption, and osteolysis on femoral side. Results. No sinking and no loosening of the stem were seen. Calar resorption was seen in 22 cases: 40%. Spot-welds was seen in almost cases on 51/55:92%. Osteolysis was seen in 9 cases, zone1;1 case, zone 7;8 cases. Clinical results were excellent as radiographic results. Conclusions. The aim to develop this system is to make optimal shape stem suitable for Japanese patients. Optimal fitting in the femoral medullary canal by KKS stem was confirmed on X-P. High occurrence rate of spot-welds showed strong stability to bone. On X-ray evaluation, no stem sinking and no loosening were found at over 10 years after operation. It proved the enough biological fixation to bone for a long time. But osteolysis occurred in 9 cases. This may come from the use of conventional polyethylene socket. Now cross-linked polyethylene socket is used and the wear of socket is expected to reduce. Off course longer follow-up of KKS system is needed. But the evaluation of KKS stem at 10 years follow-up indicated enough usefulness