Introduction. Treatment of spinal metastatic disease has evolved with the advent of advanced interventional, surgical and radiation techniques. Spinal Oligometastatic disease is a low volume disease state where en bloc resection of the tumour, based on oncological principles, can achieve maximum local control (MLC). Hybrid therapy incorporating Separation surgery (>2mm clearance of the thecal sac) and Stereotactic Ablative Radiotherapy (SABR) offer an alternative approach to achieving MLC. Hybrid therapy is also a viable option in patients eligible for SBRT who have failed conventional radiation therapy. En-bloc surgery may be a suitable option for those patients who are ineligible for or have failed SBRT. A multidisciplinary approach is particularly important in the decision-making process for these patients. Metal free instrumentation is aiding the optimization of these surgeries. The authors present a supra-regional centre's experience in managing spinal oligometastases. Methods. Retrospective review of oligometastatic spinal disease at a supra-regional centre between 2017 and 2021. Demographics, operative course, complications and Instrument type are examined. Results. Demographics: 24 patients with mean age 53.8y (range 12–77), 44% (40y–59y), 40% (60y–69y); 51% Male. Histology: Breast, Renal and Sarcoma accounted for 16.7% each; Thyroid, Prostate and Chordoma accounted for 8.3% each. Primary disease 7%, Synchronous 15%, Metachronous 78%. Instrumentation: Carbon-fibre (85%), TiAl (11%), Non-Instrumented (3%). Separation Surgery (70%), En-bloc resection/Tomita surgery (30%); SABR/Proton Beam Planned: 70%. Average length of hospital stays 19.1 days; twenty patients required intensive care admission for an average 2.7 days. 30 Day Mortality 8.3% (n=2: COVID-19 during admission and ventriculitis post discharge), 1y Mortality – 16.7%, 3y Mortality – 25%; Synchronous Mortality 75% (n=3) at 3 years. 30 Day infection rate 3%; 1y infection rate 7%. 1 Non-instrumented case developed proximal junctional failure post proton beam therapy and required a vascularised fibular strut graft. 2-year Revision for Local Recurrence 5% (Revision at 23 months). Conclusion. There are very few case series of oligometastatic spinal disease due to the relatively new concept of adjuvant SABR and its limited availability. Solid tumours pre-dominated the histology in our series with metachronous disease being the most commonly operated disease state. 92% of cases were eligible for SABR. The majority (85%) of cases were performed with Carbon-fibre instrumentation and has been shown to be safe with no mechanical failures in this series. Infection rates are in keeping with patients requiring radical radiotherapy with 3% early and 7% late. 30-day mortality was 8.3%, 1y=16.7% and 25% at last follow up. Mortality, as expected, is highest within the synchronous disease group and should be operated on sparingly. With the current management strategy, there was no local recurrence at 1 year and excellent local recurrence rate at 2 years (5%). Although radical en bloc surgery carries significant morbidity, it should be considered in selective cases to achieve MLC. All Oligometastatic cases deserve extra consideration and specialist MDT as not all are suitable for SABR. Multimodal Hybrid therapy, incorporating less invasive surgical techniques and SABR, represents a paradigm shift in achieving MLC in oligometastatic spinal disease

Introduction. Tomita En-bloc spondylectomy (TES) of L5 is one of the most challenging spinal surgical techniques. A 42-year-old female was referred with low back pain and L5 radiculopathy with background of right shoulder excision of liposarcoma. CT-PET confirmed a solitary L5 oligometastasis. MRI showed thecal sac indentation and therefore was not suitable for stereotactic ablative radiotherapy (SABR) alone. Planning Methodology. First Stage: Carbon fibre pedicle screws were planned from L2 to S2AI-Pelvis, aligned to her patient-specific rods. Custom 3D-printed navigation guides were used to overcome challenging limitations of carbon instruments. Radiofrequency ablation (RFA) of L5 pedicles prior to osteotomy was performed to prevent sarcoma cell seeding. Microscope-assisted thecal sac-tumour separation and L5 nerve root dissection was performed. Novel surgical navigation of the ultrasonic bone cutter assisted inferior L4 and superior S1 endplate osteotomies. Second stage: We performed a vascular-assisted retroperitoneal approach to L4-S1 with protection of the great vessels. Completion of osteotomies at L4 and S1 to en-bloc L5: (L4 inferior endplate, L4/5 disc, L5 body, L5/S1 disc and S1 superior endplate). Anterior reconstruction used an expandable PEEK cage obviating the need for a third posterior stage. Reinforced with a patient-specific carbon plate L4-S1 promontory. Sacrifice of left L5 nerve root undertaken. Results. Patient rehabilitated well and was discharged after 42 days. Patient underwent SABR two months post-operatively. Despite left foot drop, she was walking independently 9 months post-operatively. Conclusion. These challenging cases require a truly multi-disciplinary team approach. We share this technique for a dual stage TES and metal-free construct with post adjuvant SABR for maximum local control

Sacro-coccygeal chordomas pose a difficult diagnostic and therapeutic problem due to late presentation, large size, soft-tisue extension, difficulties in obtaining adequate resection margins, higher local recurrence rate and uncertain effectiveness of adjuvant treatment. We present a series of 21 patients of sacral chordomas obtained from Scottish Bone Tumour Registry to analyse predictors of local control and survival. The clinical and morphologic features, type of treatment and follow-up of 21 consecutive patients with sacral chordoma were retrospectively reviewed and analysed. The data were obtained from Scottish Bone Tumour Registry. The average age at time of the biopsy was 59 years (range, 12 to 82 years): twelve patients were male and nine were female. Pain was the presenting symptom in all patients. Two had intralesional (both recurred), 9 marginal (4 recurred) and 3 wide resections (1 recurred). Fifteen of the twenty-one patients were treated with adjuvant radiation therapy. In seven patients, the chordoma was inoperable and all but one were treated with adjuvant radiotherapy. Local recurrence and metastases occurred in 7 (50%) and 5 (23.8%) patients. The 5-year and 10-year survival were 38% and 14.2%, respectively. Excision of the lesion combined with adjuvant radiation therapy provided satisfactory results. Local recurrence presents a major problem in the management of sacral chordomas (50%). Intralesional resection should be avoided as it is associated with 100% local recurrence in our series

Aims. The aim of this study was to investigate the incidence and characteristics of instrumentation failure (IF) after total en bloc spondylectomy (TES), and to analyze risk factors for IF. Methods. The medical records from 136 patients (65 male, 71 female) with a mean age of 52.7 years (14 to 80) who underwent TES were retrospectively reviewed. The mean follow-up period was 101 months (36 to 232). Analyzed factors included incidence of IF, age, sex, BMI, history of chemotherapy or radiotherapy, tumour histology (primary or metastasis; benign or malignant), surgical approach (posterior or combined), tumour location (thoracic or lumbar; junctional or non-junctional), number of resected vertebrae (single or multilevel), anterior resection line (disc-to-disc or intravertebra), type of bone graft (autograft or frozen autograft), cage subsidence (CS), and local alignment (LA). A survival analysis of the instrumentation was performed, and relationships between IF and other factors were investigated using the Cox regression model. Results. A total of 44 patients (32.4%) developed IF at a median of 31 months (interquartile range 23 to 74) following TES. Most IFs were rod fractures preceded by a mean CS of 6.1 mm (2 to 18) and LA kyphotic enhancement of 10.8° (-1 to 36). IF-free survival rates were 75.8% at five years and 56.9% at ten years. The interval from TES to IF peaked at two to three years postoperatively and continued to occur over a period of time thereafter; the early IF-developing group had greater CS at one month postoperatively (CS1M) and more lumbar TES. CS1M ≥ 3 mm and sole use of frozen autografts were identified as independent risk factors for IF. Conclusion. IF is a common complication following TES. We have demonstrated that robust spinal reconstruction preventing CS, and high-quality bone grafting are necessary for successful reconstruction. Cite this article: Bone Joint J 2023;105-B(2):172–179

Aims. The aim of this study was to report the long-term prognosis of patients with multiple Langerhans cell histiocytosis (LCH) involving the spine, and to analyze the risk factors for progression-free survival (PFS). Methods. We included 28 patients with multiple LCH involving the spine treated between January 2009 and August 2021. Kaplan-Meier methods were applied to estimate overall survival (OS) and PFS. Univariate Cox regression analysis was used to identify variables associated with PFS. Results. Patients with multiple LCH involving the spine accounted for 15.4% (28/182 cases) of all cases of spinal LCH: their lesions primarily involved the thoracic and lumbar spines. The most common symptom was pain, followed by neurological dysfunction. All patients presented with osteolytic bone destruction, and 23 cases were accompanied by a paravertebral soft-tissue mass. The incidence of vertebra plana was low, whereas the oversleeve-like sign was a more common finding. The alkaline phosphatase was significantly higher in patients with single-system multifocal bone LCH than in patients with multisystem LCH. At final follow-up, one patient had been lost to follow-up, two patients had died, three patients had local recurrence, six patients had distant involvement, and 17 patients were alive with disease. The median PFS and OS were 50.5 months (interquartile range (IQR) 23.5 to 63.1) and 60.5 months (IQR 38.0 to 73.3), respectively. Stage (hazard ratio (HR) 4.324; p < 0.001) and chemotherapy (HR 0.203; p < 0.001) were prognostic factors for PFS. Conclusion. Pain is primarily due to segmental instability of the spine from its destruction by LCH. Chemotherapy can significantly improve PFS, and radiotherapy has achieved good results in local control. The LCH lesions in some patients will continue to progress. It may initially appear as an isolated or single-system LCH, but will gradually involve multiple sites or systems. Therefore, long-term follow-up and timely intervention are important for patients with spinal LCH. Cite this article: Bone Joint J 2023;105-B(6):679–687

Background

Carbon fibre (CF) instrumentation is known to be radiolucent and has a tensile strength similar to metal. A specific use could be primary or oligometastatic cancer where regular surveillance imaging and Stereotactic Radiotherapy are required.

CT images are inherently more prone to artefacts which affect Hounsfield unit (HU) measurements. Titanium (Ti) screws scatter more artefacts. Until now it has been difficult to quantify how advantageous the radiolucency of carbon fibre pedicle screws compared to titanium or metallic screws actually is.

Introduction. Patients with metastatic spinal cord compression (MSCC) or unstable spinal lesions warrant early surgical consultation. In multiple myeloma, chemotherapy and radiotherapy have the potential to decompress the spinal canal effectively in the presence of epidural lesions. Mechanical stability conferred by bracing may potentiate intraosseous and extraosseous bone formation, thus increasing spinal stability. This study aims to review the role of non-operative management in myeloma patients with a high degree of spinal instability, in a specialist tertiary centre. Methods. Retrospective analysis of a prospectively collected database of 83 patients with unstable myelomatous lesions of the spine, defined by a Spinal Instability Neoplastic Score (SINS) of 13–18. Data collected include patient demographics, systemic treatment, neurological status, radiological presence of cord compression, most unstable vertebral level and presence of intraosseous and extraosseous bone formation. Post-treatment scores were calculated based on follow-up imaging which was carried out at 2 weeks for cord compression and 12 weeks for spinal instability. A paired t-test was used to identify any significant difference between pre- and post-treatment SINS and linear regression was used to assess the association between variables and the change in SINS. Results. A significant reduction in SINS was observed from a pre-treatment average score of 14 to a score of 9, following treatment for myeloma (p<0.001). A higher initial score and a younger age were associated with a larger overall reduction in SINS (p<0.001 and p=0.02 respectively). No single variable (bisphosphates, chemotherapy, radiotherapy and steroids) had a significant association with SINS reduction. 25 (30%) patients had spinal cord compression, all of which showed radiological resolution of cord compression at 2 weeks. No patients developed neurological deterioration during treatment and all patients had an improvement in their pain scores. 64 (77%) patients had evidence of intraosseous and/or extraosseous bone formation on their follow-up scan. Conclusion. Non-operative management in the form of bracing and systemic therapy is a safe and effective treatment for spinal instability and spinal cord compression in myeloma. Treatment of unstable myelomatous lesions of the spine with or without cord compression should not follow traditional guidelines for MSCC. The decision to adopt a non-operative approach in this cohort of patients should ideally be made in a tertiary centre with expertise in multiple myeloma and in a multidisciplinary setting

Introduction. Spine is a common site for haematological malignancies. Multiple myeloma affects the spine in 70% of cases. New guidelines were published in 2015 to help manage spinal haematological malignancies. Despite neural compression or spinal instability, instrumentation of the spine should be avoided. Surgery carries significant risks of wound complications and more importantly delaying the definitive chemotherapy and radiotherapy. Cement augmentation and bracing for pain and prevention of deformity is key to the new strategies. We aimed to evaluate the different treatment modalities adopted in the spine unit at St George's hospital for spinal haematological malignancies. We compared our practice to the current guidelines published in 2015. Methods. Retrospective review of all spinal haematological malignancy patients who were discussed in the spinal MDT and managed through the spine unit at St George's hospital in the period between April 2019 and February 2021. We analysed the demographics of the patients treated in this period and compared the management modalities adopted in the unit to the current British haematological guidelines. Results. 139 patients were included in this study, 61.9% of them were male. 70 cases came through the MSCC pathway. 15 patients had their spinal involvement in the lumbar spine only below the conus. The Bilsky Grades of the other 124 cases were B0: 35.97 % 1a: 4.31%%, 1b: 7.19%, 1c: 3.59%, 2: 5.75% 3: 32.37%. 43 patients (30.9 %) had neurological deficits on presentation. 70 cases were treated conservatively (50.35%), 21 were treated with brace only (15.1%), 25 had BKP (17.98%) and 23 were treated with instrumentation (16.54%). The number of instrumented cases was small and trending down and cement augmentation and bracing were more frequently chosen for these patients. This comes in accordance to the British haematological guidelines. Conclusion. Utilising BJH 2015 guidelines we have reduced our instrumented operative case load. There is a higher percentage of BKP and Bracing in accordance to the algorithm

Aim. To assess whether oncologists are adhering to the NICE guidelines on MSCC. Methods and Results. All patients who received radiotherapy for metastatic spinal cord compression from 1. st. June 2009 – 1. st. June 2010 were identified. This information was then compared to the data collected via the MSCC Coordinator. The notes and radiological investigations were reviewed by the spinal consultant. 34 patients received radiotherapy for MSCC, 15 patients were not referred to the spinal team prior to radiotherapy. On reviewing each individual case 2 patients may have potentially benefited from surgical intervention. Conclusion. Many patients are still not referred for spinal opinion. The vast majority of these patients would not have been suitable for surgery, however, a small number may have potentially benefited

Aims

Patients with differentiated thyroid carcinomas (DTCs) have a favourable long-term survival. Spinal metastases (SMs) cause a decline in performance status (PS), directly affecting mortality and indirectly preventing the use of systemic therapies. Metastasectomy is indicated, if feasible, as it yields the best local tumour control. Our study aimed to examine the long-term clinical outcomes of metastasectomy for SMs of thyroid carcinomas.

Chordomas are slowly growing, locally aggressive primary malignant neoplasms derived from primitive notochordal cells. They tend to occur at the extreme of ages and at the two ends of the spinal column. The purpose of this study was to evaluate the presentation, morphology and behaviour of 20 non-clival, non-sacral chordoma cases. Details of 20 cases of histologically confirmed Chordomas of the mobile spine (Cervical-7, Thoracic-7, Lumbar-6) between 1967 and 2006, were extracted from the Scottish Bone Tumour Registry. The casenotes and radiographs were retrospectively reviewed. Non-sacral chordomas comprised 48.7% (20/41 cases) of total chordomas registered. There was a slight feminine predominance (11/20 cases). Mean age was 58.1 years (range, 12 to 82 years). Progressively worsening back pain was the first symptom in all the patients. Seven had intra-lesional (five recurred), six marginal (1 recurred) and 2 wide resections (none recurred). Eleven of the twenty-one patients were treated with adjuvant radiation therapy. In five patients, the chordoma was inoperable and all but one were treated with radiotherapy. There were 2 recurrences in the group of patients treated without adjuvant radiotherapy. Six patients (40%) developed local recurrences and 3 patients (15%) developed metastases. There were 4 survivors including one with local recurrence. Sixteen patients died including 3 with metastases, 7 with persistent primary disease, 1 with local recurrence and 5 with no evidence of disease or died of unrelated causes. Median survival was 19 months (mean-30.2 months), with 5- and 10-year survival rates 10% and 0.0% respectively. We found that non-sacral/non-clival chordomas had a much poorer prognosis than published in the literature. Local recurrences occurred in 40%. Intra-lesional resection should be avoided as it is associated with 71.4% local recurrence in our series

Aims

The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique.

The main form of treatment of a chordoma of the mobile spine is total en bloc spondylectomy (TES), but the clinical results are not satisfactory. Stand-alone carbon ion radiotherapy (CIRT) for bone and soft-tissue sarcomas has recently been reported to have a high rate of local control with a low rate of local recurrence. . We report two patients who underwent TES after CIRT for treating a chordoma in the lumbar spine with good medium-term outcomes. At operation, there remained histological evidence of viable tumour cells in both cases. After the combination use of TES following CIRT, neither patient showed signs of recurrence at the follow-up examination. These two cases suggest that CIRT should be combined with total spondylectomy in the treatment of chordoma of the mobile spine. Cite this article: Bone Joint J 2013;95-B:1392–5

Introduction. Aneurysmal bone cysts are uncommon benign lesions affecting the spinal column. They mostly occur in the lumbar spine and have a propensity to affect adjacent vertebrae. We describe 14 aneurysmal bone cysts affecting the spinal column from the Scottish Bone Tumour Registry with regard to assess the incidence, demography, biological behaviour and recurrence rate. Materials and Methods. We identified 14 patients with aneurysmal bone cysts affecting the spinal column. Case notes and radiographs were retrospectively reviewed from the Scottish Bone Tumour registry. Results. There were 9 female and 5 male patients. The mean age at presentation was 24.5 years (range, 6 to 62 years). The spinal location consisted of cervical (3), thoracic (4), lumbar (6) and sacral (1). The treatment included curettage without bone grafting (3), excision (7) and surgical removal with biopsy in rest. Selective angiographic embolisation was carried out in one patient with a cervical cyst and percutaneous sclerotherapy was carried out on another with a sacral cyst. There were two recurrences, of which one was treated with radiotherapy and other with repeat curettage with successful final outcome. Conclusions. The incidence of aneurysmal bone cysts was 5.5% in our registry of all the spine tumours. The recurrence occurred in 14% (2 of 14). In addition to surgery, one should be aware of the role of angiographic embolisation and radiotherapy in selected primary and recurrent ABCs

Statement of purpose. We review the current state of development of proton therapy and the implications for beam therapy in the management of primary bone tumours. Introduction. The principle of radiotherapy is to deliver a high dose, accurately, to the tumour. Conventional photon and proton therapy irradiates adjacent tissue significantly. This is reduced with intensity modulated proton therapy (IMPT). This has been demonstrably effective in treating tumours refractory to chemotherapy and conventional radiotherapy such as chrondrosarcomas and chordomas. Case Report. We present a patient with an isolated chondrosarcoma involving the anterior and posterior element of the L3 vertebral body with a significant soft tissue component displacing the IVC. The patient underwent a 2 stage en-bloc excision of the tumour: Stabilization was achieved by posterior L2-4 instrumented fusion with PEEK rods, an anterior PEEK cage and bone graft. Post-operatively the patient underwent 12 weeks of bed rest followed by rehabilitation. Due to pedicle involvement (giving a high risk of contamination) and the narrow clear margin found on histology the patient has been accepted for post-operative IMPT. Discussion. The high risk of contamination and the narrow margins presented an ideal case for post-operative IMPT. However, conventionally the stabilization would have been metallic, distorting the treatment mapping and the delivery of the IMPT, reducing any possible benefit. Thus, we used PEEK as it is proven to maintain its properties when subjected to a wide range of conditions while also being tolerant of, and not interfering with, most forms of radiation including proton therapy, maximising the chance of a positive outcome. One concern is that PEEK is less biomechanically stable then metal, hence the prolonged period of bed rest. Conclusion. This report discusses the current evidence for proton therapy while describing a successful technique for stabilization to facilitate delivery of proton treatment post-operatively

Introduction. Spinal osteosarcomas are quite rare and the optimal treatment strategy is unknown. We report a series of 9 cases of osteosarcoma of the spine treated with intralesional resection and adjuvant combination therapy in order to evaluate their clinico-pathological correlation, recurrence rate and survival. Materials and Methods. Between 1980 and 2009, nine histologically confirmed cases of primary conventional osteogenic sarcoma of the spine were identified from Scottish Bone Tumour Registry. This prospectively collected registry database was retrospectively reviewed. Results. There were 9 cases with male predominance (77.7%) at a median age of 39 years (range, 16 – 73 years) and were anatomically distributed as 2-cervical, 6-thoracic, 1-lumbar and 1-sacral. Local and distant staging and histological grading was carried out in all. Seven patients underwent intralesional (including open biopsies) and 2 marginal resections. Seven patients received adjuvant chemotherapy and 8 adjuvant radiotherapy. The overall local recurrence rate was 66.6%. All but one patient died of the disease with a median length of survival of 30 months. The 2-year and 5-year survival rates were 66.6% and 22.2% respectively. Two patients who survived more than 5 years were male patients below the age of 40 years involving thoracic spine (one had a marginal resection without receiving any adjuvant therapy subsequently had a recurrence; other one underwent intralesional resection with adjuvant chemo- and radiotherapy, died with no evidence of disease). Conclusions. Spinal osteosarcoma in Scottish patients showed a higher median age, thoracic spine and male gender predilection with overall poor prognosis. Local recurrence did not affect the survival adversely, however patients older than 40 years and metastases at presentation showed poor survival compared to age under 40 and non-metastatic presentations

Statement of purpose. We review the current state of development of proton therapy and the implications for beam therapy in the management of primary bone tumours. Introduction. The principle of radiotherapy is to deliver a high dose, accurately, to the tumour. Conventional photon and proton therapy irradiates adjacent tissue significantly. This is reduced with intensity modulation proton therapy (IMPT). This has been demonstrably effective in treating tumours refractory to chemotherapy and conventional radiotherapy such as chrondrosarcomas and chordomas. Case Report. We present a patient with an isolated chondrosarcoma involving the anterior and posterior element of the L3 vertebral body with a significant soft tissue component displacing the IVC. The patient underwent a 2 stage en-bloc excision of the tumour: Stabilisation was achieved by posterior L2-4 instrumented fusion with Peek rods and screws, an anterior Peek cage and bone graft. Post-operatively the patient underwent 12 weeks of bed rest followed by rehabilitation. Due to pedicle involvement (giving a high risk of contamination) and the narrow clear margin found on histology the patient has been accepted for post-operative IMPT. Discussion. The high risk of contamination and the narrow margins presented an ideal case for post-operative IMPT. However, conventionally the stabilisation would have been metallic, distorting the treatment mapping and the delivery of the IMPT, reducing any possible benefit. Thus, we used Peek as it is proven to maintain its properties when subjected to a wide range of conditions while also being tolerant of, and not interfering with, most forms of radiation including proton therapy, maximising the chance of a positive outcome. One concern with Peek is that it is less biomechanically stable then metal, hence the prolonged period of bed rest. Conclusion. This report discusses the current evidence for proton therapy while describing a successful technique for stabilisation to facilitate delivery of proton treatment post-operatively. Ethics approval. None Audit/service standard in trust Ethics committee COREC number:. Interest Statement. None Local grant/National grant Commercial/industry support

Aims

The aim of this study was to assess the reliability of using MRI scans to calculate the Spinal Instability Neoplastic Score (SINS) in patients with metastatic spinal cord compression (MSCC).

Aims

To evaluate the perioperative complications associated with total en bloc spondylectomy (TES) in patients with spinal tumours, based on the extent and level of tumour resection.

The revised Tokuhashi, Tomita and modified Bauer scores are commonly used to make difficult decisions in the management of patients presenting with spinal metastases. A prospective cohort study of 199 consecutive patients presenting with spinal metastases, treated with either surgery and/or radiotherapy, was used to compare the three systems. Cox regression, Nagelkerke’s R. 2. and Harrell’s concordance were used to compare the systems and find their best predictive items. The three systems were equally good in terms of overall prognostic performance. Their most predictive items were used to develop the Oswestry Spinal Risk Index (OSRI), which has a similar concordance, but a larger coefficient of determination than any of these three scores. A bootstrap procedure was used to internally validate this score and determine its prediction optimism. The OSRI is a simple summation of two elements: primary tumour pathology (PTP) and general condition (GC): OSRI = PTP + (2 – GC). This simple score can predict life expectancy accurately in patients presenting with spinal metastases. It will be helpful in making difficult clinical decisions without the delay of extensive investigations. Cite this article: Bone Joint J 2013;95-B:210–16