Objectives. Distal humerus fractures in elderly population are often comminuted and presents multiple challenges. When managed with fixation the results are often complicated with stiffness, pain, and reduced function while total elbow replacement is fraught with lifelong restrictions on load bearing which can significantly affect elderly patients who rely assistive devices for ambulation. Elbow hemiarthroplasty however, presents a viable alternative in these cases. This series evaluates the results of the distal humerus hemiarthroplasty in a single centre. Designs and methods. Data was collected retrospectively. Comprehensive case reviews were done to collect demographic, intra-operative and post-operative data. Fractures were classified as per AO classification. The primary outcome was functional outcome and range of motion (ROM). The secondary outcomes were complications and patient satisfaction. Results. 22 cases were included in this study from 2016 – 2023 majority being females (n=18). Mean age was 74years (SD −11.2). Majority fractures were AO type C3 (n=15) with two A2 type fractures managed for non-union. Pre-existing bone on bone arthritis was present in 3 cases and CT scan was done for 12 patients to assess fracture configuration. Excluding those treated for non- union the median time between fracture and surgery was 8.5 days. Follow-up of more than 6 months was available for 16 patients with median follow-up of 18 months. ROM was available for 17 patients with 13 (50%) patients having functional ROM. No patients had full extension and there was a mean lag of 20. 0. Mean flexion was 118.2. 0. Nearly 2/3. rd. patients (73%- n=16) were satisfied with the surgery with no problems in activity of daily living. Complications seen were ulnar neuropathy (n=3), heterotopic ossification(n=2) and periprosthetic fracture (n=1). Conclusion. This single centre study suggests good outcomes following distal humerus hemiarthroplasty. It is a reasonable alternative to fixation and total elbow arthroplasty in complex fractures

The distal humerus represents 1% of all primary bone tumours. Endoprosthetic replacement can potentially improve function and provide good pain relief. We present out experience with the custom made Stanmore elbow endoprosthesis used after resection of malignant tumours of the distal humerus. Between 1970–2009 we carried out 19 endoprosthetic replacments for malignant tumours of the distal humerus. 10 were a result of metastasis and 9 were primary bone tumours. 7 patients had a pathological fracture as their first presentation and 3 had pathological fractures after the diagnosis was made. 11 patients died between 3 months to 16 year following surgery. The mean survival of the patient group was 7.1 years (range 3 months to 37 years). 4 patients underwent a revision EPR and one patient underwent two revision EPR's due to loosening. Two patients underwent maintenance procedures (rebushing) due to wear of the poly bushing. We have had no revisions since the design of hte implant was changed to a floppy hinge design. One patient underwent an above elbow amputation four years after surgery due to local recurrence. There were no early post operative infections. One patient developed a sinus requiring multiple wound explorations, one year after insertion of the endoprosthesis for a sarcoma. This patient was infection free till the time of death 3 years later. There were no nerve palsies, periprosthetic fractures or wound problems. The mean TES score was 72% (59–78%) in the surviving patients at review. As the majority of the patients were implanted for metastatic disease the initial reliablity and low complication rate of the procedure, in our series, confirms that this is a suitable reconstruction for patients in significant metastatic pain from a destructive lesion of the distal humerus, rapidly restoring function and relieving pain in a predictable manner

Introduction:. Distal humerus fractures as well as elbow fracture dislocation are often accompanied by soft tissue damage that warrants early fixation with an external fixator. The distal humerus is a hazardous area for placement of an external fixator due to the close proximity of the radial nerve to the humerus in this area. No known safe zone has been identified on the lateral border of the humerus to avoid radial nerve damage. The aim of this study was to record the incidence of radial nerve damage by placing two 4 mm pins into the humerus and to note the relation of the nerve to the pins. Methods:. Two 4 mm pins used to fix an external fixator were drilled into the lateral border of the humerus at points 100 mm and 70 mm proximal to the lateral epicondyle of both arms of 39 cadavers. The 30 mm interval between the pins is the interval between the pins in a pinblock of a commonly-used external fixator. The arms were dissected by medical students and the incidence of radial nerve damage was recorded. Statistical analysis was done using a Fischer's exact test to identify the incidence of nerve damage relative to pin insertion. The number of damaged nerves was compared to the number of non-damaged nerves. A design based Chi Square test was carried out to test left and right arms. The proportions of interest were estimated along a 95% confidence interval. Results:. The radial nerve was hit (damaged) by 56.4% of the proximal and 20.5% of the distal pins. The radial nerve ran posterior to the proximal pin in 2.57% of arms and 0% to the distal pin. Conclusion:. Although no clear safe zone could be established, pins should be placed closer than 100 mm from the lateral epicondyle and as posterior on the humerus as possible to minimize the risk for radial nerve damage. Keywords: Radial nerve, external fixation, humerus fractures

Trans-articular coronal shear fractures of the distal humerus pose a significant challenge to the surgeon in obtaining an anatomical reduction and rigid fixation and thereby return of good function. A variety of approaches have been described which include the extended lateral and anterolateral approaches and arthroscopically-assisted fixation for non-comminuted fractures. Fixation methods include open or percutaneous cannulated screws and headless compression screws directed either anterior to posterior or posterior to anterior. We describe an illustrated, novel approach to this fracture which is minimally invasive but enables an anatomical reduction to be achieved. A 15 year old male presented with a Bryan and Morrey type 4 fracture as described by McKee involving the left distal humerus. He was placed in a lateral position with the elbow over a support. A posterior longitudinal incision and a 6cm triceps split from the tip of the olecranon was made. The olecranon fossa was exposed and a fenestration made with a 2.5mm drill and nibblers as in the OK (Outerbridge-Kashiwagi) procedure. A bone lever was then passed though the fenestration and used to reduce the capitellar and trochlear fracture fragments into an anatomical position with use of an image intensifier to confirm reduction. The fracture was then fixed with two headless compression screws from posterior to anterior into the capitellar and trochlear fragments (see images). Early mobilisation and rehabilitation were commenced. Follow-up clinical examination and radiographs at six weeks revealed excellent range-of-motion and function with anatomical bony union. We believe that this novel approach to this fracture reduces the amount of soft tissue dissection associated with conventional approaches and their associated risks and also enables earlier return to function with restoration of anatomy

Adequate exposure is a prerequisite for treatment of distal humeral fractures. In this study, we compared the clinico-radiological and functional outcome of TRAP approach with that of olecranon osteotomy for distal humerus fractures. 27 patients with distal humerus fractures were randomized into 2 groups: Group 1 (n=14, TRAP approach), Group 2 (n=13, Olecranon osteotomy). All patients were operated with bi-columnar fixation. All patients were mobilized from day 2. Follow-up evaluation was done at 1, 3, 6 and 12 months. All patients achieved union. The mean surgical time was higher in group 1 (120 min) as compared to group 2 (100 min). The final ROM was higher in group 1 (1160) as compared to group 2 (850). Two patients in group 2 needed posterior release. 5 patients in group 2 had hardware complications related to olecranon osteotomy and needed removal. Two patients in Group 1 had transient ulnar nerve paraesthesias. There was no difference in triceps power in both groups. Our results demonstrate that TRAP approach is extensile and safe enough in treating these complex fractures with better final ROM and fewer complications

Background. Level 1 studies for fracture management of upper extremity fractures remains rare. The influence of these studies on management trends has yet to be evaluated. The purpose of this study was to examine alterations in national trends managing mid-shaft clavicle and intra-articular distal humerus fractures (DHF) surrounding recent Level 1 publications. Methods. We retrospectively reviewed a comprehensive Medicare (2005–2012) and Humana (2007–2014) patient population database within the PearlDiver supercomputer (Warsaw, IN, USA) for DHF and mid-shaft clavicle fractures, respectively. Non-operative management and open reduction internal fixation (ORIF) were reviewed for mid-shaft clavicle fractures. ORIF and total elbow arthroplasty (TEA) were reviewed for DHF. Total use and annual utilization rates were investigated using age limits defined in the original Level 1 studies. Results. A total of 4,929 clavicle patients between 15 and 59 years, and 106,535 DHF patients greater than 65 years of age were coded. There was no significant change in annual volume of mid-shaft clavicle fractures and DHF coded (p=0.078 and p=0.614, respectively). Among clavicle patients there was a significant increase in ORIF utilization following the publication of the Level 1 study (p=0.002), and a strong, positive correlation was evident (p=0.007). No significant change in annual TEA (p=0.515) utilization for DHF was seen. Conclusion. A significant increase in the utilization of ORIF for clavicular fractures was observed following the publication of supporting Level 1 evidence. This was not observed following similar evidence in managing DHF, as no increase in utilization of TEA was observed

The aim of this abstract is to show that acute osteomyelitis is one of the most feared complication of orthopedic surgery. A rapid and aggressive treatment is mandatory in order to avoid significant bone loss, joint destruction and, in most cases, salvage of the limb. After apparent cure of the infection, sequelae must be addressed. In this case, the joint destruction was important, so reconstruction procedures where impossible. In a superficial and relatively small joint such as the elbow, it is preferred to do an arthrodesis than an arthroplasty because the risk of reactivation of the infection with implant involvement is very important.

We present a case report of a 69 years old woman, who had a supra-intra-condylar fracture (AO 13-C1) of the right humerus. She was treated with open reduction and internal fixation with 2 internal lag screws and 2 external lag screws. After 6 weeks, she was admitted with a dislocated elbow associated with pain, loss of limb function, cubita nerve palsy and a purulent discharge from the surgical wound. She started vancomycin and was submitted to surgery with debriment, hardware removal and fixation with an external fixator was used. The local signs of infection disappeared progressively. After normalization of the laboratory parameters of infection, the patient was submitted to an elbow arthrodesis using a posterior contour plate.

The elbow achieved solid fixation and infection was eradicated, at least for the time being, allowing the patient to use the upper limb in her daily live activities.

The treatment of post operative acute osteomyilits is challenging, In this case, after apparent solution of the infection, a solid fixation of the elbow was achieved, allowing the use of the upper limb in the patient daily activities.

Total elbow arthroplasty (TEA) has been shown to be a treatment option for elderly patients with complex distal humeral fractures and osteoporotic bone. The published results have often included rheumatoid patients who traditionally would be expected to do well from elbow arthroplasty. Only short-term results have been published using this technique in non-rheumatoid patients.

The current study contains the largest number and longest follow-up of non-rheumatoid patients whose fractures have been treated with a non-custom TEA. In total there were 26 patients, mean age 72 years, 22 female and 4 male, 25% dominant arm. The mean follow-up was of 5 years. There was 1 case of loosening, 1 radial nerve palsy and 2 cases of heterotrophic ossification. At final review the mean range of flexion/extension was 97.5 degrees and the mean range of pronation/supination was 151.75 degrees. The mean Mayo Elbow Performance score was 92.

We would suggest that TEA provides a very satisfactory outcome in elderly patients with complex distal humeral fractures, the benefit of which can be observed at a mean of 5 years.

Introduction

Treatment for distal third shaft fractures of humerus is very challenging. They are commonly treated with plating. Plating has complications of iatrogenic radial nerve palsy. We report our case series of distal third fractures of humerus treated with retrograde Halder Humeral Nail.

We report the case of a 12-year-old boy with flexion loss in the left elbow caused by deficient of the concavity corresponding to the coronoid fossa in the distal humerus. The range of motion (ROM) was 15°/100°, and pain was induced by passive terminal flexion. Plain radiographs revealed complete epiphyseal closure, and computed tomography (CT) revealed a flat anterior surface of the distal humerus; the coronoid fossa was absent. Then, the bony morphometric contour was surgically recreated using a navigation system and a three-dimensional elbow joint model. A three-dimensional model of the elbow joint was made preoperatively and the model comprising the distal humerus was milled so that elbow flexion flexion of more than 140° could be achieved against the proximal ulna and radius. Navigation-assisted surgery (contouring arthroplasty) was performed using CT data from this milled three-dimensional model. Subsequently, an intraoperative passive elbow flexion of 135° was obtained. However, active elbow flexion was still inadequate one year after operation, and a triceps lengthening procedure was performed. At the final follow-up one year after triceps lengthening, a considerable improvement in flexion was observed with a ROM of −12°/125°. Plain radiographs revealed no signs of degenerative change, and CT revealed the formation of the radial and coronoid fossae on the anterior surface of the distal humerus. Navigation-assisted surgery for deformity of the distal humerus based on a contoured three-dimensional model is extremely effective as it facilitates evaluation of the bony morphometry of the distal humerus. It is particularly useful as an indicator for milling the actual bone when a model of the mirror image of the unaffected side cannot be applied to the affected side as observed in our case

Olecranon Osteotomy is a common approach used in the management of intraarticular distal humerus fractures. Significant complication rates have been associated with this procedure, including non-union rates of 0–13% and implant removal rates between 12–86%. This study is a multicentre retrospective study involving the largest cohort of olecranon osteotomies in the literature, examining implant fixation types, removal rates and associated complications. Patients were identified between 2007 and 2017 (minimum one year follow-up) via Canadian Classification of Health Interventions (CCI) coding and ICD9/10 codes by our health region's data information service. CCI intervention codes were used to identify patients who underwent surgery for their fracture with an olecranon osteotomy. Reasons for implant removal were identified from a chart review. Our primary outcome was implant removal rates. Categorical data was assessed using Chi square test and Fischer's Exact test. Ninety-nine patients were identified to have undergone an olecranon osteotomy for treatment of a distal humerus fracture. Twenty patients had their osteotomy fixed with a plate and screws and 67 patients were fixed with a tension band wire. Eleven patients underwent “screw fixation”, consisting of a single screw with or without the addition of a wire. One patient had placement of a cable-pin system. Of patients who underwent olecranon osteotomy fixation, 34.3% required implant removal. Removal rates were: 28/67 for TBW (41.8%), 6/20 plates (30%), 0/1 cable-pin and 0/11 for osteotomies fixed with screw fixation. Screw fixation was removed less frequently than TBW p<.006. TBW were more commonly removed than all other fixation types p<.043. Screws were less commonly removed than all other fixation types p<.015. TBW were more likely to be removed for implant irritation than plates, p<.007, and all other implants p<.007. The average time to removal was 361 days (80–1503 days). A second surgeon was the surgeon responsible for the removal in 10/34 cases (29%). TBWs requiring removal were further off the olecranon tip than those not removed p=.006. TBWs were associated with an OR of 3.29 (CI 1.10–9.84) for implant removal if implanted further than 1mm off bone. Nonunion of the osteotomy occurred in three out of 99 patients (3%). K-wires through the anterior ulnar cortex did not result in decreased need for TBW removal. There was no relation between plate prominence and the need for implant removal. There was no association between age and implant removal. The implant removal rate was 34% overall. Single screw fixation was the best option for osteotomy fixation, as 0/11 required hardware removal, which was statistically less frequent than TBW at 28/67. Screw fixation was removed less frequently than TBW and screw fixation was less commonly removed than all other fixation types. Only 6/20 (30%) plates required removal, which is lower than previously published rates. Overall, TBW were more commonly removed than all other fixation types and this was also the case if hardware irritation was used as the indication for removal. Nonunion rates of olecranon osteotomy were 3%

We aimed to assess the functional outcomes of elderly patients with isolated comminuted distal humerus fractures that were managed non-operatively. Retrospective analysis of patients over 65 years presenting to our unit between 2005–2015 was undertaken. 67 patients were identified, 7 had immediate TEA, 41 died and 5 were lost to follow-up leaving 14 available for review. Mean Follow-up was 55 months(range 17–131) Patient functional outcomes were measured using VAS scores for pain at rest and during activity, and the Oxford Elbow Score (OES). Need for conversion to TEA and complications were recorded. The mean age at injury was 76 years(range 65–90) of which 79%(11/14) were females. The mean score on the OES was 46(range 29 – 48). The mean VAS score at rest was 0.4(range 0–6) and the mean VAS score during activity was 1.3(range 0–9). 93%(13/14) of patients reported no pain (0 out of 10 on the numeric scale for pain) in their injured elbow at rest and 79%(11/14) reported no pain during activity. No patients converted to TEA and there were no complications. Non-operative management of comminuted distal humerus fractures should be considered for elderly patients, avoiding surgical risks whilst giving satisfactory functional outcomes in this low demand group

Introduction. Hemiarthroplasty is a treatment option for comminuted fractures and non-unions of the distal humerus. Unfortunately, the poor anatomical fit of off-the-shelf distal humeral hemiarthroplasty (DHH) implants can cause altered cartilage contact mechanics. The result is reduced contact area and higher cartilage stresses, thus subsequent cartilage erosion a concern. Previous studies have investigated reverse-engineered DHH implants which reproduce the shape of the distal humerus bone or cartilage at the articulation, but still failed to match native contact mechanics. In this study, design optimization was used to determine the optimal DHH implant shape. We hypothesized that patient-specific optimal implants will outperform population-optimized designs, and both will optimize simple reverse-engineered designs. Methods. The boney geometries of six elbow joints were created based on cadaver arm CT data using a semi-automatic threshold technique in 3D Slicer. CT scans were also obtained with the elbows denuded and disarticulated, such that the high contrast between hydrated cartilage and air could be exploited in order to reconstruct cartilage geometry. Using this 3D model data, finite element contact models were created for each elbow, where bones (distal humerus, proximal ulna and radius) were modelled as rigid surfaces covered by non-uniform thickness layers of cartilage. Cartilage was modelled as a Neo-Hookean hyperelastic material (K = 0.31 MPa, G = 0.37 MPa), and frictionless contact was assumed. In order to simulate hemiarthroplasty, the distal humerus cartilage surface was replaced by either a rigid surface in the shape of the subchondral bone (bone reverse engineered or BRE design), or a surface offset from the bone by some distance, which was defined parametrically and modified by an optimization algorithm. Simple flexion-extension with constant balanced muscle loads was simulated in ABAQUS (Fig 1), and resulting contact areas and contact stresses were calculated. For each specimen, the contact mechanics of the intact and DHH reconstructed joints were calculated. A design optimization algorithm in Matlab was used to determine the optimal offset distance which resulted in contact stress distributions on the ulna and radius which most closely resembled their intact conditions. This procedure was repeated in order to generate specimen-optimal offsets, as well as population-optimal offsets. Results. The population-optimal offset distance was 0.72 mm; whereas the specimen-optimal offsets ranged from 0.52 to 1.04 mm. Compared to the BRE design, which is effectively an offset distance of 0 mm, contact area generally increased at both the ulna (Fig 2) and radius (Fig 3) when either optimized design was used. On average, the specimen-optimal implant designs yielded only slightly larger contact areas than the population-optimal offsets, and only at mid-flexion (40–60 deg). Neither optimization strategy increased contact areas to those of the intact joint. Conclusions. Design optimization is a promising technique for improving patient-specific implants by offering customization in terms of contact mechanics, instead of simply reproducing osseous geometry. In this study, our models predict a large increase in contact area if optimal offsets are used when designing subject-specific DHH, and a population-optimal offset distance seems to be just as good as a subject-optimal offset. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Purpose of the study. To evaluate the outcome of the Modified French osteotomy for the correction of cubitus varus resulting from a supracondylar distal humerus fracture in children. Description of methods. A retrospective review of 90 children, aged 3 to 14, who underwent a modified French osteotomy between 1986 and 2012 for the correction of cubitus varus as a result of a supracondylar distal humerus fracture. Case notes and radiographs were reviewed. The carrying angle was measured clinically and radiologically pre-operatively, post-operatively and at latest follow up. Comparison was made with the unaffected side. The outcome was graded as good if the correction of the carrying angle was within 5 degrees of the unaffected side, satisfactory if the correction was more than 5 degrees of the unaffected side but cubitus valgus was restored and poor if there was persistence of cubitus varus post correction. Any intra-operative and post-operative complications were documented. Summary of results. The average age at the time of osteotomy was 8 years. Sixty-two percent of the patients were male. The left elbow was affected 61% of the time. The average delay from time of fracture to osteotomy was 24 months. The average post-operative follow up was 3.5 months. With regard to the correction of the cubitus varus, 83% of patients had a good outcome, 17% had a satisfactory outcome, with no poor outcomes. Post-operative complications were documented in 6 patients, 3 of which required re-operation. Conclusion. The modified French osteotomy has been shown to be a safe and effective treatment for cubitus varus following supracondylar distal humerus fractures in children. NO DISCLOSURES

The problem of retained drain fragments is a well known but under reported complication in the literature. The authors present the case of a 66 years old male, who suffered a right distal humerus fracture luxation six years ago that was treated conservatively. He went to the emergency service with fever and right elbow purulent drainage. Physical examination showed deformity, swelling and fluctuation of the right elbow with purulent drainage through cutaneous fistula. The x-ray showed instable inveterate pseudarthrosis of the distal humerus. Leucocytosis and neutrophylia with increased CRP were presente in the blood tests and the patient started empiric treatment with Ceftiaxone IV. A MRSA was isolated in cultural exam of the exsudate, and a six weeks treatment with Vancomycin IV was iniciated. Exhaustive surgical cleaning was performed and two plastic foreing bodies (fragmented drains) were removed. At the time of discharge the patient was afebrile, with normal analytical parameters and negative culture tests. The orthopaedic surgeon should considerate the presence of a foreign body in patients with infected abcess and traumatic or surgery previous history

Intraarticular fractures of the distal humerus comprise 1% of all fractures in adults. Triceps reflecting and olecranon osteotomy approach provide adequate exposure in intraarticular fracture with its own advantage and disadvantages. Forty consecutive patients with fractures of the distal humerus were treated over a 36-month period. The patients were randomly allotted into two groups; group A consists of twenty patients with olecranon osteotomy and group B consists of twenty patients with triceps reflecting approach. In both the groups fracture was fixed using orthogonal or parallel plating techniques. Clinical outcome was assessed using the DASH SCORE, radiological union and complications was noted in both the group and compared. In group A the mean DASH score was 15.9 points. Three patients underwent a second procedure for hardware removal, 2 patients had non-union at osteotomy site, one patient had transient ulna nerve neuropraxia and one patient had superficial infection. In group B the mean DASH score was 14 points. There was no statistical significance between both groups regarding final outcome except complications were more in osteotomy approach. We conclude both approach is an effective procedure with an excellent or good functional outcome but osteotomy approach has more complications

Introduction. Recently, computer-aided orthopaedic surgery has enabled three dimensional (3D) preoperative planning, navigation systems and patient matched instrument, and they provide good clinical results in total knee arthroplasty. However, the preoperative planning methods and the criteria in total elbow arthroplasty (TEA) still have not sufficiently established due to the uncertainty of 3D anatomical geometry of the elbow joints. In order to clarify the 3D anatomical geometry, this study measured 3D bone models of the normal elbow joints. Additionally this study attempted to apply the 3D preoperative planning to ordinary surgery. Then the postoperative position of implant has evaluated as compared with the position in 3D preoperative planning. Methods. Three dimensional bone measurements on 4 normal cases were performed. Three dimensional bone models were constructed with CT image using Bone Viewer®(ORTHREE Co., Ltd.). TEA was performed with FINE® Total Elbow System (Nakashima Medical Co., Ltd.) for 3 rheumatoid arthritis (RA) cases (Fig. 1). Three dimensional preoperative planning was based on this bone measurement, and postoperative position of implant were evaluated. The postoperative assessments were evaluated by superimposing preoperative planning image on postoperative CT image using Bone Simulator® (ORTHREE Co., Ltd.). This study only covers humeral part. Results. The results of 3D bone measurements on 4 normal cases shows the average internal rotation angle between the flexion-extension axis and the epicondyles axis in the distal humerus was 2.2 degrees. The average valgus tilt of the distal humerus was 3.7 degrees. Postoperative position of humeral component for 3 RA cases was installed at proximal and valgus position compared to the preoperative planning. Discussion. This study indicates that ordinary two dimensional criteria and 3D anatomical one in the elbow joint may be different in several bony landmarks such as rotation, varus and valgus. Additionally these results show the differences between postoperative position of implant and preoperative position in 3D planning. More studies need to be conducted to validate postoperative evaluation and preoperative planning

Introduction. Stress shielding of bone around the stem components of total shoulder replacement (TSR) implants can result in bone resorption, leading to loosening and failure. Titanium is an ideal biomaterial for implant stems; however, it is much stiffer than bone. Recent advances in additive manufacturing (AM) have enabled the production of parts with complex geometries from titanium alloys, such as hollow or porous stems. The objective of this computational study is to determine if hollow titanium stems can reduce stress shielding at the proximal humerus. We hypothesize that hollow TSR implant stems will reduce stress shielding in comparison with solid stems and the inner wall thickness of the hollow stem will be a design parameter with a direct effect on bone stresses. Methods. Using a previously developed statistical shape and density model (SSDM) of the humerus based on 75 cadaveric shoulders, a simulated average CT image was created. Using MITK-GEM, the cortical and trabecular bones were segmented from this CT image and meshed with quadratic tetrahedral elements. Trabecular bone was modeled as an isotropic and inhomogeneous material, with the Young's modulus defined element-by-element based on the corresponding CT densities. Cortical bone was assumed isotropic with a uniform Young's modulus of 20 GPa. The Poisson's ratio for all bone was 0.3. The distal humerus was fully constrained. Bone stresses were calculated by performing finite element analyses in ABAQUS with a 320 N force and 2 Nm frictional moment applied to the articular surface of the humeral head, based on an in vivo study during 45 degrees of shoulder abduction. Subsequently, the humeral head was resected and reamed to receive solid- and hollow-stemmed implants with identical external geometries but three different inner wall thicknesses (Figure 1). The identical surrounding bone meshes for the intact and reconstructed bones allowed element-by-element stress comparisons. The volume-weighted average changes in cortical and trabecular bone von Mises stresses were calculated, (wrt the intact humerus), as well as the percentage of bone volume experiencing a relative increase or decrease in stress greater than 10%. Results. Results for all four implant designs are summarized (Figure 2). The solid stem resulted in the biggest average change in von Mises stresses (4% decrease in cortical and 6% increase in cancellous bone stress). The solid stem also resulted in the largest volume of bone experiencing a decrease in stress. Comparing the hollow stems, the thinnest shell wall resulted in the smallest changes in cortical bone stress, and the lowest volumes of bone experiencing a decrease in stress. Interestingly, this design caused the most cancellous bone to experience an increase in stress. Discussion. These results suggest a marginal improvement in the bone-implant mechanics of hollow versus solid stems, and that thinner shell walls perform better. That said, the improvements over the solid stem design are minimal. Further increasing the compliance of these stems, e.g. by adding pores, may improve their performance. Future work will focus on optimizing hollow and porous stem designs, and the possibility of leveraging their hollow design for drug delivery. For any figures or tables, please contact the authors directly

Background. The procedures of total elbow and shoulder replacements increased 6% to 13% annually from 1993 to 2007 with revision-related burden increasing from 4.5% to 7%. The revisions of the shoulder and elbow prostheses due to aseptic loosening, periprosthetic fractures, infections have led to the use of standard or custom-made implants due to significant bone loss. This study reports our experience in the management of complicated primary and revisions of total shoulder and elbow replacements with significant humeral bone loss and in metabolic diseases of the elbow and shoulder treated with bone resection using The Mosaic Humeral Replacement System. Patients and Materials. A total of 20 patients underwent total elbow or shoulder arthroplasty using the Mosaic Humeral Replacement System (Biomet, UK). The Mosaic system was used in 8 shoulder arthroplasties (Group A) and in 12 elbow arthroplasties (Group B). The underlying pathologis in Group A included 2 malunited proximal humerus fracture, 1 humeral osteomyelitis, 1 shoulder chondrosarcoma, 1 aggressive Gigantic Cell Tumor with prosthetic fracture, 2 metastatic lytic lesion, and 1 failed fixation of non-union proximal humerus. Figure 1 shows Mosaic implant after complex fracture of proximal humerus. Reasons for Mosaic arthroplasty in Group B included 3 humeral component revisions due to periprosthetic fracture, 1 prosthesis breaking-up with fractures, 1 revision of loose Souter Strathclyde prosthesis, 1 loose prosthesis due to infection, 1 highly comminuted elbow fracture, 1 aseptic loosening of humeral component of total elbow replacement, 3 revision of total elbow replacement due loosening and 1 pathological distal humerus fracture due to metastasis. Figure 2&3 shows pre- and post-operative Mosaic implant following complex periprosthetic fracture of distal humerus. Clinical Observation/Discussion. The Mosaic Humeral Replacement System is a complete system for complex revision, salvage/oncology, and complex humeral fractures. It is a completely modular system which can be adapted to different patient anatomies and indications. It has been designed to face several surgical challenges, including reattaching soft tissues, properly tensioning the glenohumeral joint and restoring joint function. It is a cost-effective procedure with the benefits of a custom made humeral component in a standard tray. Our study shows that good results can be achieved with this form of treatment. Radiological assessment of all patients showed a satisfactory position of the implant with appropriate margin of bony resection. One patient with proximal and another one with distal humeral Mosaic replacement had late infection. One patient had aseptic loosening 3 years after distal humeral replacement. Most of the patients had satisfactory improvement in range of movement and chronic pain. While primary clinical observations and imaging results indicate acceptable results with Mosaic arthroplasty; a realistic assessment can only be achieved in long-term using the appropriate outcome measures. At the present we continue to regularly assess the patients clinically and radiologically and by means of Liverpool elbow score for distal and Quick- DASH for proximal Mosaic Humeral Replacement System and plan to report the long-term results in due time

Background. Humeral version is the twist angle of the humeral head relative to the distal humerus. Pre-operatively, it is most commonly measured referencing the transepicondylar axis, although various techniques are described in literature (Matsumura et al. 2014, Edelson 1999, Boileau et al., 2008). Accurate estimation of the version angle is important for humeral head osteotomy in preparation for shoulder arthroplasty, as deviations from native version can result in prosthesis malalignment. Most humeral head osteotomy guides instruct the surgeon to reference the ulnar axis with the elbow flexed at 90°. Average version values have been reported at 17.6° relative to the transepicondylar axis and 28.8° relative to the ulnar axis (Hernigou, Duparc, and Hernigou 2014), although it is highly variable and has been reported to range from 10° to 55° (Pearl and Volk 1999). These studies used 2D CT images; however, 2D has been shown to be unreliable for many glenohumeral measurements (Terrier 2015, Jacxsens 2015, Budge 2011). Three-dimensional (3D) modeling is now widely available and may improve the accuracy of version measurements. This study evaluated the effects of sex and measurement system on 3D version measurements made using the transepicondylar and ulnar axis methods, and additionally a flexion-extension axis commonly used in biomechanics. Methods. Computed tomography (CT) scans of 51 cadaveric shoulders (26 male, 25 female; 32 left) were converted to 3D models using medical imaging software. The ulna was reduced to 90° flexion to replicate the arm position during intra-operative version measurement. Geometry was extracted to determine landmarks and co-ordinate systems for the humeral long axis, epicondylar axis, flexion-extension axis (centered through the capitellum and trochlear groove), and ulnar long axis. An anatomic humeral head cut plane was placed at the head-neck junction of all shoulders by a fellowship trained shoulder surgeon. Retroversion was measured with custom Matlab code that analysed the humeral head cut plane relative to a reference system based on the long axis of the humerus and each elbow axis. Effects of measurement systems were analyzed using separate 1-way RM ANOVAs for males and females. Sex differences were analyzed using unpaired t-tests for each measurement system. Results. Changing the measurement reference significantly affected version (p<0.001). The ulnar axis method consistently resulted in higher measured version than either flexion-extension axis (males 9±1°, females 14±1°, p<0.001) or epicondylar axis (males 8±1°, females 12±1°, p<0.001). See Figure 1. Version in males (38±11°) was 7° greater than females (31±12°) when referencing the flexion-extension axis (p=0.048). Conclusion. Different measurement systems produce different values of version. This is important for humeral osteotomies; if version is assessed using the epicondyles pre-operatively and subsequently by the ulna intra-operatively, then the osteotomy will be approximately 10° over-retroverted. For any figures or tables, please contact authors directly (see Info & Metrics tab above).