INTRODUCTION. Bone tumour resection and subsequent reconstruction remains challenging for the surgeon. Obtaining adequate margins is mandatory to decrease the risk of local recurrence. Improving surgical margins quality without excessive resection, reducing surgical time and increasing the quality of the reconstruction are the main goals of today's research in bone tumour surgical management. With the outstanding improvements in imaging and computerised planning, it is now a standard. However, surgical accuracy is essential in orthopaedic oncologic surgery (Grimmer 2005). Patient specific instruments (PSI) may greatly improve the surgeon's ability to achieve the targeted resection. Thanks to its physical support, PSI can physically guide the blade yielding to a better control over the cutting process (Wong, 2014). Surgical time might significantly be reduced as well when compared to conventional method or navigated procedure. Finally, reconstruction may gain in rapidity and quality especially when allograft is the preferred solution as PSI can be designed as well for allograft cutting (Bellanova, 2013). Since 2011, PSI have systematically been used in our institution for bone tumour resection and when applicable allograft reconstruction. This paper reports the mid- to long-term medical outcomes on a large series. MATERIALS AND METHODS. Between 2011 and 2016, we systematically used PSI to remove bone tumours in 30 patients. The pre-operative planning involved the tumour delineation drawn on MRI by the surgeon. The MRI and obtained tumour volume were transferred to the CT-scan by image fusion (co- registration). Cutting planes were positioned around the tumour including a safe margin. The PSI were designed to ensure a sufficient stability but kept thin enough to limit the bone exposure. The PSI was manufactured by 3D-printing in a biocompatible and sterilisable material. PSI has been intraoperatively to cut the bone with predetermined margins. Medical files were reviewed for large data collection: type, size and site of the tumour, pre-and post-operative metastatic status, bone and soft tissues resection margins, local recurrence, use of an allograft and a PSI for graft adjustment or not for the reconstruction, the fusion of the allograft when applicable, the follow-up time and early/late complications. RESULTS. Over a period of 5 years, 30 patients were operated on with PSI (10 osteosarcomas, 4 chondrosarcomas, 10 Ewing sarcomas and 6 other types of bone tumours). Mean follow-up was 27±20 months. 18 cases out of 30 have more than 2 years follow-up and 13 out of 30 have more than 3 years of follow-up. Mean operating time was 6h02±3h44. Mean size of the tumours was 8,4±4,7cm and location was the upper limb in 5 cases, inferior limb in 15 cases and the pelvis in 10 occurrences. Metastatic disease developed postoperatively in 5 patients. Surgical margins in the bone were R0 in all cases but one case where a R1 surgery was planned to preserve a nerve root. We did not observe any local recurrence in the bone. Within soft tissues, margins were classified as R0 in 28 patients and R1 in 2 patients. In 26 cases, an allograft was used to reconstruct the bone defect. In 23 of those patients, the allograft was selected by CT scan and cut using a PSI. In the 3 allografts cut free-handily, only one demonstrated a fusion. Of the 23 cut with a guide, 12 fused completely, 2 demonstrated a partial fusion and 9 were not fused at the last follow-up. At the last follow-up, 2 patients were dead of disease, 5 were alive with metastatic disease and 23 were alive without disease. DISCUSSION. Oncology is probably the field where PSI can bring the largest advantage when compared to the conventional procedure. Several papers have reported the use of PSI for bone tumour resection. All of them have shown very promising results on in-vitro experiments (Cartiaux 2014), cadaver experiment (Wong 2012) or small clinical series (Bellanova 2013, Gouin, 2014). None of these papers report a large patient series associated with a clinically relevant follow-up. This series is the first mid- to long-term follow-up series involving PSI tumour surgery. These results are showing strong evidences of clinical improvements. It comes into contradiction with PSI for total knee arthroplasty where controversial results on the patient's outcome has been reported (Thienpont 2014). R0 margin has been systematically obtained for all bone cuttings, and local recurrence has been strongly decreased (3%) when compared to the usual recurrence rates published in the literature (from 15% to 35% according to the location). Allograft fusion seems improved as well thanks to the shape-matching of the selected allograft and a close contact between host and allograft at bony junctions. With a longer follow-up, these evidences should be stronger to definitely make PSI the best option for bone tumour resection

Recently, several preliminary reports have been issued on the application of computer assistance to bone tumour surgery. Surgical navigation systems can apply three-dimensional images such as CT and MR images to intraoperative visualization. Although CT is better at describing cortical bone status, MRI is considered the best method for defining the extent of marrow involvement for bone tumours and for planning surgical resection in bone tumour surgery. There have been a few reports on the application of MR imaging to navigation-assisted bone tumour surgery through CT–MR image fusion. However, the CT–MRI fusion technique requires additional costs and exposure of the patient to radiation from the preoperative CT, as well as additional time for image fusion. Above all, the image fusion process is a kind of registration (image to image registration) that inevitably leads to registration error. Herein we describe a new method for the direct application of MR images to navigation-assisted bone tumour surgery as an alternative to CT–MRI fusion. Six patients with an orthopaedic malignancy were employed for this method during navigation-assisted tumour resection. Resorbable pin placement and rapid 3-dimensional spoiled gradient echo sequences made the direct application of MR images to computer-assisted bone tumour surgery without CT–MR image fusion possible. A paired-point registration technique was employed for patient-image registration in all patients. It took 20 min on average to set up the navigation (range 15 to 25 minutes). The mean registration error was 0.98 mm (range 0.4 to 1.7 mm). On histologic examination, distances from tumours to resection margins were in accord with preoperative plans. Mean duration of follow-up was 25.8 months (range 18 to 32 months). No patient had a local recurrence or distant metastasis at the last follow-up. Direct patient-to-MRI registration is a very useful method for bone tumour surgery, permitting the application of MR images to intraoperative visualization without any additional costs or exposure of the patient to radiation from the preoperative CT scan

The surgical treatment of bone tumours can result in large perioperative blood loss due to their large sizes and hypervascularity. Preoperative embolisation has been successfully used to downgrade vascularity, thus reducing perioperative blood loss and its associated complications. Prior to embolization era, blood loss as high as 18,500mL have been reported peri-opratively. Twenty-six patients with a variety of bone tumours (average size 10.5×7.5×5.5cm), who underwent pre-operative embolisation between 2005 and 2009, were retrospectively studied. The group comprised of 17 females and 9 males. Their mean age was 38 years old. All patients underwent surgical resection within 48 hours of embolization. Mean blood loss was 796mL and required on average 1.1units of blood. We experienced no complications. Pre-operative arterial embolisation of large, richly vascular bone tumours in anatomically difficult positions, is a safe and effective method of downstaging vascularity and reducing blood loss

Resecting bone tumours within the pelvis is highly challenging and requires good cutting accuracy to achieve sufficient margins. Computer-assisted technologies such as intraoperative navigation have been developed for pelvic bone tumour resection. Patient-specific instruments have been transposed to tumour surgery. The present study reports a series of 11 clinical cases of PSI-assisted bone tumour surgery within the pelvis, and assesses how accurately a preoperative resection strategy can be replicated intraoperatively with the PSI. The patient series consisted in 11 patients eligible for curative surgical resection of primary bone tumor of the pelvis. Eight patients had a bone sarcoma of iliac bone involving the acetabulum, two patients had a sacral tumor, and one patient had a chondrosarcoma of proximal femur with intra-articular hip extension. Resection planning was preoperatively defined including a safe margin defined by the surgeon from 3 up to 15 mm. PSI were designed using a computer-aided design software according to the desired resection strategy and produced by additive manufacturing technology. Intraoperatively, PSI were positioned freehand by the surgeon and fixed on the bone surface using K-wires. The standard surgical approach has been used for each patient. Dissection was in accordance with the routine technique. There was no additional bone exposure to position the PSI. Histopathological analysis of the resected tumor specimens was performed to evaluate the achieved resection margins. Postoperative CT were acquired and matched to the preoperative CT to assess the local control of the tumor. Two parameters were measured: achieved resection margin (minimum distance to the tumor) and location accuracy (maximum distance between achieved and planned cuttings; ISO1101 standard). PSI were quick and easy to use with a positioning onto the bone surface in less than 5 minutes for all cases. The positioning of the PSI was considered unambiguous for all patients. Histopathological analysis classified all achieved resection margins as R0 (tumor-free), except for two patients : R2 because of a morcelised tumour and R1 in soft tissues. The errors in safe margin averaged −0.8 mm (95% CI: −1.8 mm to 0.1 mm). The location accuracy of the achieved cut planes with respect to the desired cut planes averaged 2.5 mm (95% CI: 1.8 to 3.2 mm). Results in terms of safe margin or the location accuracy demonstrated how PSI enabled the surgeon to intraoperatively replicate the resection strategies with a very good cutting accuracy. These findings are consistent with the levels of bone-cutting accuracy published in the literature. PSI technology described in this study achieved clear bone margins for all patients. Longer follow-up period is required but it appears that PSI has the potential to provide clinically acceptable margins

Aims. Present the outcomes of those patients diagnosed with Ewing's Sarcoma of the foot within the past 10 years and treated at the Royal National Orthopaedic Hospital's Bone Tumour Unit, Stanmore. Methods. Retrospective study of the cases identified from the pathology database. Notes reviewed for presentation, treatment and follow up. TESS (Toronto Extremity Salvage Score) and MSTS (Musculoskeletal tumour score) were calculated. Results. 6 patients identified with positive diagnosis of Ewing's Sarcoma of the Foot. Male:Female ratio of 5:1. Age range 15–31 (Mode 25). 4 cases skeletal, 2 extra skeletal. All cases reviewed by supra-regional MDT and received adjuvant and neo-adjuvant chemotherapy. All except one patient underwent limb-salvage surgery. The MDT decision for the remaining patient was that amputation was the only viable surgical option but the patient and his parents requested radiotherapy without surgical treatment. Mean survival 40 months (15–107 months). All patients survive at time of submission. Mean MSTS/TESS scores 93% (80–100%) and 94.6% (85–100) respectively. Discussion. All patients reported a delay between first presentation and referral to the sarcoma unit. This experience is common across the literature for this rare pathology. Lowest scores were submitted by the two patients who had amputation of their great toe. All patients are happy with their outcome and decision to salvage their limb. All patients scored themselves as “not at all disabled” and two stated this would not have been their response if they had lost their foot. Conclusion. Amputation is psychologically difficult to accept and patients are more receptive to limb salvage surgery. Our patients demonstrate good functional outcome. Our experience at Stanmore suggests that limb salvage surgery with adequate MDT surveillance for Ewing's Sarcoma of the Foot can be a viable alternative to amputation

Skeletal Cryptococcosis although rare has been reported in immunodeficient individuals and in particular those with HIV. We present a case in a HIV- negative patient who presented to the London Sarcoma service masquerading as a primary bone tumour and review the relevant literature. A 71 year old lady presented with a three month history of right submammary pain associated with a new lump. Chest radiographs showed an osteolytic lesion in the right 6. th. rib. CT scans demonstrated mediastinal lymphadenopathy and numerous lung nodules. Differential diagnosis of the lesion included TB abscess, myeloma, lymphoma or as a primary lung tumour presenting with hilar lymphadenopathy and necrotic skeletal metastasis. CT guided biopsy was performed with histology showing necrotising granulomatous inflammation with numerous yeast like organisms in keeping with Cryptococcus fungal infection. She was treated successfully with a six week course of voriconazole. Cryptococcal skeletal infections can cause significant morbidity and mortality and should be considered as a rare cause of lytic osseous lesions

Introduction. Bony tumours of the foot account for approximately 3% of all osseous tumours. However, literature regarding os calcis and talar tumours comprises individual case reports, short case series or literature reviews with no recent large series. Methods. We retrospectively reviewed the medical notes and imaging for all patients with calcaneal or talar tumours recorded in the Scottish Bone Tumour Registry since the 1940's. Demographics, presentation, investigation, histology, management and outcome were reviewed. Results. 34 calcaneal tumours and 23 talar tumours were identified. Calcaneal tumours. 2:1 male prevalence, mean age at presentation 30, average length of symptoms 9 months. 4 cases presented with pathological fracture. 21 benign tumours including 6 unicameral bone cysts, 3 chondroblastoma, and a wide variety of individual lesions. 13 malignant tumours comprising 6 osteosarcoma, 5 chondrosarcoma and 2 Ewings sarcoma. Talar Tumours. male to female ratio 3:1, mean age at presentation 28, average length of symptoms 5 months. 20 benign cases including 7 osteoid osteoma, 4 chondroblastoma, and several individual lesions. 3 malignant lesions comprising 2 chondrosarcoma, 1 osteosarcoma. Discussion. Tumours of the hindfoot frequently are delayed in diagnosis due to their rarity and lack of clinician familiarity. They are more common in men, especially talar tumours, which are most commonly benign osteoid osteoma or chondroblastoma. Calcaneal tumours have 1 in 3 risk of malignancy and cover a wider variety of lesions. Osteosarcoma of the foot tends to present later than other anatomical regions. Outcome is dependant on early diagnosis, timely surgery and most importantly neo-adjuvant chemotherapy. Diagnosis is often made on plain radiograph but MRI is the gold standard. Despite their rarity clinicians should maintain a high index of suspicion as accurate and timely diagnosis is important to management and outcome

Objective

of this study was to analyse results of two stage revisions in infected megaprostheses in lower limb.

Primary malignant bone tumours are a scarce entity with limited population-based data from developing countries. The aim of the study is to investigate the frequency and anatomical distribution of primary malignant bone tumours in a local South African population. This will be an epidemiological retrospective study. Data will be used of patients that were diagnosed with primary malignant bone tumours over a period of nine years spanning from 1 January 2014 to 31 December 2022. This data will be received from private and government laboratories. Data to be considered are type of primary malignant bone tumours diagnosed, incidence of primary malignant bone tumours over a period of nine years and the most common anatomical sites of primary malignant bone tumours. The rationale behind our study is to assess the frequency of different primary malignant bone tumours in another geographic area of South Africa and to compare these findings to local and international literature. With a projected increase in diagnosis of primary malignant bone tumours in developing countries it is important to have more available data about primary malignant bone tumours from these areas to have a better understanding of these conditions and to understand the impact of the burden they impose on healthcare systems so that management of these conditions can also be improved. Preliminary results show that 23.83% of primary malignant bone tumours occurred in the age group 0–24 years of age, 49.22% in the 25–59 age group and 26.95% in the 60+ age group. The most common tumour that occurred was chondrosarcoma (49.21%) followed by osteosarcoma (41.80%) then Ewing's sarcoma (4,69%) and lastly chordoma (4.30%). From the 256 samples that met the inclusion criteria the five most common anatomical sites were distal femur (63), proximal tibia (41), proximal humerus (38), pelvis (34) and proximal femur (20)

En bloc resection for primary bone tumours and isolated metastasis are complex surgeries associated with a high rate of adverse events (AEs). The primary objective of this study was to explore the relationship between frailty/sarcopenia and major perioperative AEs following en bloc resection for primary bone tumours or isolated metastases of the spine. Secondary objectives were to report the prevalence and distribution of frailty and sarcopenia, and determine the relationship between these factors and length of stay (LOS), unplanned reoperation, and 1-year postoperative mortality in this population. This is a retrospective study of prospectively collected data from a single quaternary care referral center consisting of patients undergoing an elective en bloc resection for a primary bone tumour or an isolated spinal metastasis between January 1st, 2009 and February 28th, 2020. Frailty was calculated with the modified frailty index (mFI) and spine tumour frailty index (STFI). Sarcopenia, determined by the total psoas area (TPA) vertebral body (VB) ratio (TPA/VB), was measured at L3 and L4. Regression analysis produced ORs, IRRs, and HRs that quantified the association between frailty/sarcopenia and major perioperative AEs, LOS, unplanned reoperation and 1-year postoperative mortality. One hundred twelve patients met the inclusion criteria. Using the mFI, five patients (5%) were frail (mFI ³ 0.21), while the STFI identified 21 patients (19%) as frail (STFI ³ 2). The mean CT ratios were 1.45 (SD 0.05) and 1.81 (SD 0.06) at L3 and L4 respectively. Unadjusted analysis demonstrated that sarcopenia and frailty were not significant predictors of major perioperative AEs, LOS or unplanned reoperation. Sarcopenia defined by the CT L3 TPA/VB and CT L4 TPA/VB ratios significantly predicted 1-year mortality (HR of 0.32 per one unit increase, 95% CI 0.11-0.93, p=0.04 vs. HR of 0.28 per one unit increase, 95% CI 0.11-0.69, p=0.01) following unadjusted analysis. Frailty defined by an STFI score ≥ 2 predicted 1-year postoperative mortality (OR of 2.10, 95% CI 1.02-4.30, p=0.04). The mFI was not predictive of any clinical outcome in patients undergoing en bloc resection for primary bone tumours or isolated metastases of the spine. Sarcopenia defined by the CT L3 TPA/VB and L4 TPA/VB and frailty assessed with the STFI predicted 1-year postoperative mortality on univariate analysis but not major perioperative AEs, LOS or reoperation. Further investigation with a larger cohort is needed to identify the optimal measure for assessing frailty and sarcopenia in this spine population

Introduction. Patient-reported outcome measures (PROMs) has gained momentum in the orthopaedic literature. The GOAL-LD (Gait Outcomes Assessment List for Limb Deformity) incorporates the framework of The WHO International Classification of Functioning, Disability and Health and correlates highly with the Paediatric Outcomes Data Collection Instrument (PODCI) when applied in a limb reconstruction setting. The Royal Children's Hospital Melbourne, Australia, supported by The University of Melbourne is designing and implementing a Limb Reconstruction Registry, prospectively enrolling patients with a number of key conditions and provide a mechanism for capturing surgical data and PROMs at regular follow-up intervals. LimbDREAM (The Limb Reconstruction Registry of Experience, Aspiration and Measures) has begun recruiting participants, and this paper serves as a narrative review of our design and implementation process. Materials & Methods. After provision of a research grant, audit was conducted to examine local case mix and estimate recruitment based on conditions selected. Literature review was focussed on (i) registries in the paediatric limb reconstruction domain and (ii) use of PROMs across conditions selected. A high-level process-flow chart was constructed in order to inform governance and staffing requirements in addition to REDCap Database structure. Local as well as scalable deployment was considered. Alpha and beta testing was performed by principal and associate investigators prior to participant recruitment. Results. Audit identified 6 condition streams for inclusion: Congenital limb deficiencies, congenital pseudarthrosis of the tibia, bone dysplasias, bone tumours, amputation, and complex deformity of other etiology. Literature review identified 20 PROMs used across these conditions, with limited validation studies and significant implementation heterogeneity. REDCap database design took longer than anticipated (planned 10 months, actual 18 months) before being recruitment ready, due to the complexity of ensuring data collection logic would work across highly diverse patient journeys. Initial recruitment across all streams has been promising. Email and text message reminders have proved helpful in increasing survey return rates. Conclusions. Prospective collection of PROMs as well as surgical data via a standardized dataset will provide the basis for future condition-specific research, with the ability to support nested trials. Implementation requires forethought with regard to time frames and staffing for non-automated steps as well as data integrity review. The next phase of the LimbDREAM project will be to integrate use of the Registry into our weekly Limb Reconstruction Meeting to ensure that operative plans and data are captured close to the point of care

Aims. The aticularis genu (AG) is the least substantial and deepest muscle of the anterior compartment of the thigh and of uncertain significance. The aim of the study was to describe the anatomy of AG in cadaveric specimens, to characterize the relevance of AG in pathological distal femur specimens, and to correlate the anatomy and pathology with preoperative magnetic resonance imaging (MRI) of AG. Methods. In 24 cadaveric specimens, AG was identified, photographed, measured, and dissected including neurovascular supply. In all, 35 resected distal femur specimens were examined. AG was photographed and measured and its utility as a surgical margin examined. Preoperative MRIs of these cases were retrospectively analyzed and assessed and its utility assessed as an anterior soft tissue margin in surgery. In all cadaveric specimens, AG was identified as a substantial structure, deep and separate to vastus itermedius (VI) and separated by a clear fascial plane with a discrete neurovascular supply. Mean length of AG was 16.1 cm ( ± 1.6 cm) origin anterior aspect distal third femur and insertion into suprapatellar bursa. In 32 of 35 pathological specimens, AG was identified (mean length 12.8 cm ( ± 0.6 cm)). Where AG was used as anterior cover in pathological specimens all surgical margins were clear of disease. Of these cases, preoperative MRI identified AG in 34 of 35 cases (mean length 8.8 cm ( ± 0.4 cm)). Results. AG was best visualized with T1-weighted axial images providing sufficient cover in 25 cases confirmed by pathological findings.These results demonstrate AG as a discrete and substantial muscle of the anterior compartment of the thigh, deep to VI and useful in providing anterior soft tissue margin in distal femoral resection in bone tumours. Conclusion. Preoperative assessment of cover by AG may be useful in predicting cases where AG can be dissected, sparing the remaining quadriceps muscle, and therefore function. Cite this article: Bone Joint Open 2020;1-9:585–593

Osteosarcoma is the most common primary bone tumour worldwide. This disease presents a formidable challenge to the orthopaedic surgeon, with a mortality rate of 30 per cent, even after surgical clearance. Aberrant Wnt signalling has been implicated in the pathogenesis osteoblastic tumours. The objective of this study is 2 fold- to investigate if osteosarcoma does indeed demonstrate aberrant Wnt signaling, and if so, does osteosarcoma respond to a novel Wnt inhibitor(ETC159). This can potentially lead to the development of a new adjuvant treatment modality for osteosarcoma. A novel Wnt signaling pathway protein antibody (YJ5) was used in immunihistochemistry staining of clinical osteosarcoma samples. A Wnt high osteosarcoma cell line(SJSA-1) was then implanted subcutaneously in a mouse model. These mice were treated with a novel PORCN inhibitor, ETC 159 for a period of 4 weeks in a two-arm randomised control study. The results of treatment were evaulated by clinical outcome parameters as well as immunohstochemistry. 100 per cent of clinical osteosarcoma samples demonstrated increased WLS expression and Wnt protein expression. SJSA-1 showed no significant decrease in tumour volume after 30 days of drug treatment (3070 SD 625 mm3 vs 3480 SD 433 mm3 p= 0.605 and 2060 SD 209 vs 1677 SD 213 mm3 p=0.219 respectively). Significantly, SJSA-1 demonstrated increased tumour necrosis in the treatment arm(30–60 percent increase across all samples p < 0 .005) Treated tumours also demonstrated markedly less angiogenesis compared to the non treatment arm. Osteosarcoma demonstrates aberrant Wnt signaling in a large percentage of cases. The use of a novel PORCN inhibitor ETC 159 for the treatment of Osteosarcoma has a marked effect on tumour necrosis. Our results suggest that ETC159 may cause tumour necrosis by inhibiting angiogenesis within the tumour. Further evaluation and understanding of the mechanism of Wnt singaling in regulating tumour pathogenesis may hold the potential for developing a curative therapeutic drug for this deadly disease

Purpose of the study. To review the primary bone tumours of the spine treated at our unit. Description of methods. Retrospective review of folders and x-rays of all the patients with primary bone tumours of the spine treated at our unit between 2005 and 2012. All haematological tumours were excluded. Summary of results. We treated 15 cases during this period. The median age at presentation was 36 years (8–65). There was a significant delay from onset of symptoms to diagnosis in most cases (median 7 months). Histological diagnoses included:. -Benign tumours.  Active. Hemangioma. 3. Osteoid osteoma. 1. Eosinophilic granuloma. 1.  Aggressive. Osteoblastoma. 1. Giant cell tumours. 2. Aneurysmal bone cysts. 4. -Malignant tumours.  Osteosarcomas. 2.  Leiomyosarcoma of bone. 1. A variety of definitive surgical methods were utilised. Seven patients had a debulking or intralesional resection of the tumour. Eight patients had an attempted marginal excision. This was achieved through anterior surgery only in 1 case, posterior only surgery in 6 cases and combination anterior and posterior surgery in 8 cases. The anterior and posterior surgery was performed in a single sitting in 5 cases and in a staged fashion in 3 cases. Adjuvant radiotherapy and chemotherapy were used where indicated. Three cases presented with significant neurological impairment. Of these 2 made a significant recovery. There were no cases of neurological deterioration following surgery. All 3 patients with malignant tumours died in the follow up period. We had 1 case of hardware failure due to chronic sepsis. Conclusion. Primary bone tumours of the spine are associated with a significant delay in diagnosis. Surgical treatment options and adjuvant therapy should be tailor made for each case depending on the diagnosis. Acceptable results with minimal complications can be achieved with this approach

Introduction. Clear operative oncological margins are the main target in malignant bone tumour resections. Novel techniques like patient specific instruments (PSIs) are becoming more popular in orthopaedic oncology surgeries and arthroplasty in general with studies suggesting improved accuracy and reduced operating time using PSIs compared to conventional techniques and computer assisted surgery. Improved accuracy would allow preservation of more natural bone of patients with smaller tumour margin. Novel low-cost technology improving accuracy of surgical cuts, would facilitate highly delicate surgeries such as Joint Preserving Surgery (JPS) that improves quality of life for patients by preserving the tibial plateau and muscle attachments around the knee whilst removing bone tumours with adequate tumour margins. There are no universal guidelines on PSI designs and there are no studies showing how specific design of PSIs would affect accuracy of the surgical cuts. We hypothesised if an increased depth of the cutting slot guide for sawblades on the PSI would improve accuracy of cuts. Methods. A pilot drybone experiment was set up, testing 3 different designs of a PSI with changing cutting slot depth, simulating removal of a tumour on the proximal tibia (figure 1). A handheld 3D scanner (Artec Spider, Luxembourg) was used to scan tibia drybones and Computer Aided Design (CAD) software was used to simulate osteosarcoma position and plan intentioned cuts (figure 1). PSI were designed accordingly to allow sufficient tumour. The only change for the 3 designs is the cutting slot depth (10mm, 15mm & 20mm). 7 orthopaedic surgeons were recruited to participate and perform JPS on the drybones using each design 2 times. Each fragment was then scanned with the 3D scanner and were then matched onto the reference tibia with customized software to calculate how each cut (inferior-superior-vertical) deviated from plan in millimetres and degrees (figure 3). In order to tackle PSI placement error, a dedicated 3D-printed mould was used. Results. Comparing actual cuts to planned cuts, changing the height of the cutting slot guide on the designed PSI did not deviate accuracy enough to interfere with a tumour resection margin set to maximum 10mm. We have obtained very accurate cuts with the mean deviations(error) for the 3 different designs were: [10mm slot: 0.76±0.52mm, 2.37±1.26°], [15mm slot: 0.43±0.40mm, 1.89±1.04°] and [20mm: 0.74±0.65mm, 2.40±1.78°] respectively, with no significant difference between mean error for each design overall, but the inferior cuts deviation in mm did show to be more precise with 15mm cutting slot (p<0.05) (figure 2). Discussion. Simulating a cut to resect an osteosarcoma, none of the proposed designs introduced error that would interfere with the tumour margin set. Though 15mm showed increased precision on only one parameter, we concluded that 10mm cutting slot would be sufficient for the accuracy needed for this specific surgical intervention. Future work would include comparing PSI slot depth with position of knee implants after arthroplasty, and how optimisation of other design parameters of PSIs can continue to improve accuracy of orthopaedic surgery and allow increase of bone and joint preservation. For figures/tables, please contact authors directly.

Reconstruction of pelvic bone defect after resection for bone tumours is a challenging procedure especially when the hip joint is involved due to the anatomy and the complex biomechanical and structural function of the pelvic ring. This surgery is associated to high complication rate. The additive 3D printing technology allows us to produce trabecular titanium custom based implants with an accurate planning of resection using bone cutting jigs. From August 2013 to January 2017, we treated 8 patients for bone pelvic sarcoma with custom-made osteotomy jigs (Nylon) and custom-made trabecular titanium prosthesis produced through rapid prototyping technology based on mirroring of the contralateral hemipelvis. Mean follow up time was 18 months (range 2–30) Wide margins were obtained in all cases, in one a local recurrence developed. Surgical time was 4 hours average (from 180 to 250 mins). No postoperative complications were reported. Rapid prototyping is a promising technique in order to achieve wide surgical margins and restore the anatomy in pelvic bone tumour resection as well as reducing complications

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. Aseptic loosening is the most common mode of failure of massive endoprostheses. Introduction of Hydroxyapatite coated collars have reduced the incidence of aseptic loosening. However bone growth is not always seen on these collars. Objectives. The aims of our study were to determine the extent of osseous integration of Hydroxyapatite coated collars, attempt a grading system for bone growth and to determine the effect of diagnosis, surgical technique and adjuvant therapy on bone growth. Methods. We reviewed the records and radiographs of 58 patients who had a massive endoprosthesis implanted by two surgeons in our unit over the last five years. Revision surgeries were recorded separately. Bone growth was graded 1–4 based on appearance in antero-posterior and lateral radiographs. Results. Three groups were identified. Group 1-Resections for primary bone tumours (33 patients), Group 2-resections for metastatic bone disease (22 patients) and Group 3- Resections for non tumour indications (3 patients). Overall, 60% of patients had grade 1, 12% had grade 2, 19% had grade 3 and 9% had grade 4 osteointegration. Grade 3 or 4 Collar osteointegration was found in 37% of patients in Group 1, 9% in group 2 and 67% in group 3. 5% of patients with grade 1 integration, 100% patients with grade 2 integration and none of the patients with grade 3 or 4 integration underwent revision for aseptic loosening. Appearance or widening of a gap between the resected bone end and the collar indicated loosening and impending revision. Proximal humeral replacements had the lowest rate of osteointegration (12%). Adjuvant therapy did not affect osteointegration. Conclusion. Osteointegration of collars is seen more often after resection of primary bone tumours. The role of collars in metastatic tumour surgery is questionable. Our radiographic grading system of bone growth predicted aseptic loosening

Background. Endoprosthetic reconstruction is an established method of treatment for primary bone tumours in children. Traditionally these were implanted with cemented intramedullary fixation. Hydroxyapatite collars at the shoulder of the implant are now standard on all extremity endoprostheses, but older cases were implanted without collars. Uncemented intramedullary fixation with hydroxyapatite collars has also been used in an attempt to reduce the incidence of problems such as aseptic loosening. Currently there are various indications that dictate which method is used. Aims. To establish long term survivorship of cemented versus uncemented endoprosthesis in paediatric patients with primary bone tumours. Methods. This was a retrospective study of 441 endoprostheses implanted in 367 consecutive patients aged 18 years or less, between 1973 and 2005. This included the use of case notes, hospital databases and a radiological review. Information obtained included patient demographics, indications for surgery, anatomical distribution and type of implants, complications and survivorship. Results. Mean age was 13.9 (range 3 - 38). 210 patients were male, 157 were female. There were 364 primaries and 77 revision implants. 161 extendable and 280 definitive prostheses. 282 patients had osteosarcoma, 54 had Ewing's sarcoma and 28 had other diagnoses. Commonest sites included 197 distal femoral replacements, 85 proximal tibial implants and 57 were in the upper limb. Kaplan-Meier survival analysis was used to compare anatomical sites and method of fixation. Upper limb implants had the best long term survival. Failure rates for distal femoral replacements were compared for cemented fixation (21.7% due to aseptic loosening) with cement plus hydroxyapatite collars (3.1%) and uncemented implants with hydroxyapatite collars (6.2%). Conclusions. In the distal femur cemented fixation with hydroxyapatite collars gave the best survivorship in definitive primary prostheses. Uncemented fixation with hydroxyapatite collars gave the best survivorship in extendable prostheses. Cemented fixation without hydroxyapatite gave the worst survivorship

Introduction. Despite the advances in adjuvant chemotherapy and surgical techniques, the diagnosis of a bone tumour still carries with it a significant risk of mortality. This study investigates factors affecting survival, in patients treated for malignant tumours of bone using Endoprosthetic replacement (EPR). Methods. Our tertiary referral musculoskeletal tumour unit has taken referrals over 40 years. Electronic patient records have been prospectively kept on all patients seen since 1986 and data has been entered retrospectively for patients seen between 1966 and 1986. A consecutive series of 1264 patients underwent endoprosthetic reconstruction; after 158 patients were excluded, 1106 patients were left in the study group. Factors including diagnosis, size of tumour, surgical margins, percentage tumour necrosis following chemotherapy, tumour site, local recurrence, decade of reconstruction, fracture and post-operative deep infection were analysed. Results. Overall population survival was 58.4% at 5 years, 50.5% at 10 years and 44.6% at 20 years. Significant prognostic factors on cox-regression analysis included locally recurrent disease (p<0.001), metastatic disease (p<0.001), chemotherapy (p<0.001), percentage tumour necrosis after chemotherapy (p=0.001), tumour size (p<0.001), post-operative surgical margin (p<0.001), fracture (p<0.001) and post-operative deep infection (p=0.05). Univariate analysis showed proximal femoral site (p=0.01) and EPRs after 1991 (p=0.05) were significant factors. Patients diagnosed with a deep infection within 2.5 years from implantation had 63.2% 10 year survival, compared to 49.4% in the non infected group. When stratified by diagnosis this was significant in patients with myeloma (p=0.01) and a showed strong trend in those with osteosarcoma (p=0.1). Trends towards better survival with Staphylococcal infections (p=0.2) were not demonstrated with other organisms. Discussion and conclusion. Several known prognostic factors were demonstrated for malignant bone tumours but there was evidence for increased survival after deep post-operative infection. The authors feel the results of this study and other recent evidence warrant further investigation