The perioperative utility of 3D printed models in complex surgical care: feedback from 106 cases

INTRODUCTION

3D models are an emerging tool for surgical planning, providing an augmented method for the visualisation of a patient's anatomy. As their use increases, more data about the utility of these models is critical to inform budget allocation. This study provides the most comprehensive analysis to date for the use of 3D models in perioperative management.

METHODS

3D models for complex surgical cases in NHS hospitals were delivered alongside a surgeon feedback survey. The survey on the model's utility had been designed alongside the university data analytical team and focused on five areas: surgical planning and diagnosis, economic impact, impact on intraoperative and preoperative time, effect on communication and direct impact on the patient.

RESULTS

There were 106 models used by 63 surgeons for complex surgical cases between May 2020 and March 2021, across multiple surgical specialties. The models were reported to have benefits in all perioperative areas, with 92.5% of responses agreeing that the 3D model was a better method for diagnosis and planning than traditional 2D techniques. Benefits were reported on preoperative planning (92.4%), economic savings due to equipment selection (54.4%), reduction in surgical time (41.5%) and surgeon-to-surgeon communication (92.6%).

CONCLUSION

3D models were shown to have a wide range of benefits in a surgical setting. The reduction in surgical time could have the potential to help alleviate surgical backlogs. With more widespread use and optimisation of costs the use of 3D models could become the standard for unusual and complex surgical cases.

The risks following the exposure to radiation associated with the surgical correction of limb deformities in children are minimal

Aims

The aim of this study was to quantify the risk of developing cancer from the exposure to radiation associated with surgery to correct limb deformities in children.

Patients and Methods

A total of 35 children were studied. There were 19 girls and 16 boys. Their mean age was 11.9 years (2 to 18) at the time of surgery. Details of the radiological examinations were recorded during gradual correction using a Taylor Spatial Frame. The dose area product for each radiograph was obtained from the Computerised Radiology Information System database. The effective dose in millisieverts (mSv) was calculated using conversion coefficients for the anatomical area. The lifetime risk of developing cancer was calculated using government-approved Health Protection Agency reports, accounting for the age and gender of the child.

Results

Correction was undertaken in five femurs, 18 tibiae, and 12 feet. The median duration of treatment was 45 months (11 to 118). The mean effective dose was 0.31 mSv (0.05 to 0.64) for the femur, 0.29 mSv (0.01 to 0.97) for the tibia, and 0.027 mSv (0.001 to 0.161) for the foot. The cumulative exposure gave ‘negligible’ risk in 26 children and ‘minimal’ risk in nine children, according to Public Health England categories. These results are below the mean annual background radiation in the United Kingdom.

Conclusion

The lifetime attributable risk of developing cancer from repeated exposure to radiation was negligible or minimal in all children. This is the first study to quantify the exposure to radiation from serial radiographs in children with limb deformities who are treated surgically using circular external fixation, linking this to the risk of developing cancer. Cite this article: Bone Joint J 2019;101-B:241–245.

What is the incidence of late detection of developmental dysplasia of the hip in England?: a 26-year national study of children diagnosed after the age of one

AIMS

The aim of this study was to establish the incidence of developmental dysplasia of the hip (DDH) diagnosed after one-year of age in England, stratified by age, gender, year, and region of diagnosis.

PATIENTS AND METHODS

A descriptive observational study was performed by linking primary and secondary care information from two independent national databases of routinely collected data: the United Kingdom Clinical Practice Research Datalink and Hospital Episode Statistics. The study examined all children from 1 January 1990 to 1 January 2016 who had a new first diagnostic code for DDH aged between one and eight years old.

RESULTS

The incidence of late-diagnosed DDH was 1.28 per 1000 live births. Within the study population, 754 children were identified with a diagnosis of DDH after one-year of age. Of all late diagnoses, 536 (71.1%) were detected between one to two years of age. There were 608 female patients (80.6%) and 146 male patients (19.4%), giving a female-to-male ratio of 4.2:1. Distribution was evenly spread throughout England.

CONCLUSION

The incidence of late-diagnosed DDH has not been reduced from that reported 35 years ago, prior to the introduction of the national selective screening programme for DDH. Cite this article: Bone Joint J 2019;101-B:281-287.

Osteonecrosis following treatment for childhood acute lymphoblastic leukaemia: The Southampton Children's Hospital experience

PURPOSE

To determine the prevalence of osteonecrosis (ON) in children following treatment of acute lymphoblastic leukaemia (ALL), characterise these cases and review treatment methods.

METHODS

All children diagnosed and treated for ALL between 01 January 2003 and 31 December 2013 at our centre were retrospectively reviewed. Logistic regression was used to investigate risk factors for ON occurrence.

RESULTS

Of 235 children treated for ALL, 48/235 (20.4%) children suffered musculoskeletal symptoms necessitating radiological investigation. A total of 13 (5.5%) had MRI-diagnosed ON, with a median diagnosis time of 12 months (interquartile range 10 to 14) following initiation of chemotherapy.ON affected 40 joints in 13 children. The most commonly involved joints were hips (14 joints in eight patients) and knees (12 joints in seven patients).Older age at ALL diagnosis was associated with significantly increased risk of development of ON per year (odds ratio 1.35, 95% confidence interval 1.17 to 1.57, p < 0.001).Eight children underwent at least one surgical intervention. Joint arthroplasty was undertaken in nine joints of four children at a mean age of 18.3 years. All patients who underwent hip arthroplasty had previously received core decompression, with a mean time of 27.8 months (18 to 33) between treatments.

CONCLUSIONS

ON is a significant complication of ALL treatment. Our results suggest risk stratification for development of ON by age, and targeted monitoring of high-risk joints is possible. ON treatment is varied with little evidence base.

MRI performed on dedicated knee coils is inaccurate for the measurement of tibial tubercle trochlear groove distance

OBJECTIVE

Tibial tubercle trochlear groove distance (TTD) is a significant factor in patello-femoral instability. Initially described on CT scans with the knee in full extension, the measurement has been validated on MR scans. Dedicated knee MRI coils have subsequently superseded both CT and MRI body coils for knee imaging. However, the knee rests in partial flexion within the dedicated knee coil. The objective of this study is to investigate whether images from dedicated knee MRI coils produce different TTD measurements from MR body coils.

MATERIALS AND METHODS

Thirty-two symptomatic knees (27 patients) had simultaneous knee MR scans performed in both a dedicated knee coil and a body coil. TTD measurements were independently compared to assess whether the coil type used affected TTD.

RESULTS

Patients' ages ranged from 10 to 27 years (mean 15 years). Mean TTD in the dedicated knee coil (partially flexed knee) was 11.3 mm compared with 19.9 mm in the body coil (that permits full knee extension). The mean difference was 8.6 mm, which was highly significant (p < 0.0001, unpaired t test). Inter-rater correlation co-efficient was 96 %. Of the knees that recorded a "normal" TTD on the dedicated knee coil, 60-100 % recorded a "pathological" TTD on body coil images, depending on which diagnostic value for "normal" cut-off was used.

CONCLUSION

This study has identified a highly significant difference in TTD measurement when knees are scanned in a dedicated knee coil with the knee partially flexed, compared with an MR body coil. It is critical for surgeons and radiologists managing patello-femoral instability to appreciate this profound difference. TTD measurement taken from knees scanned in dedicated knee coils may lead to patients being falsely re-assured or erroneously denied surgery.

A tissue engineering strategy for the treatment of avascular necrosis of the femoral head

BACKGROUND & PURPOSE

Skeletal stem cells (SSCs) and impaction bone grafting (IBG) can be combined to produce a mechanically stable living bone composite. This novel strategy has been translated to the treatment of avascular necrosis of the femoral head. Surgical technique, clinical follow-up and retrieval analysis data of this translational case series is presented.

METHODS

SSCs and milled allograft were impacted into necrotic bone in five femoral heads of four patients. Cell viability was confirmed by parallel in vitro culture of the cell-graft constructs. Patient follow-up was by serial clinical and radiological examination. Tissue engineered bone was retrieved from two retrieved femoral heads and was analysed by histology, microcomputed tomography (μCT) and mechanical testing.

RESULTS

Three patients remain asymptomatic at 22- to 44-month follow-up. One patient (both hips) required total hip replacement due to widespread residual necrosis. Retrieved tissue engineered bone demonstrated a mature trabecular micro-architecture histologically and on μCT. Bone density and axial compression strength were comparable to trabecular bone.

CONCLUSIONS

Clinical follow-up shows this to be an effective new treatment for focal early stage avascular necrosis of the femoral head. Unique retrieval analysis of clinically translated tissue engineered bone has demonstrated regeneration of tissue that is both structurally and functionally analogous to normal trabecular bone.

From bench to clinic and back: skeletal stem cells and impaction bone grafting for regeneration of bone defects

Tissue engineering offers enormous potential for bone regeneration. Despite extensive in vitro and in vivo work, few strategies translate into clinical practice. This paper describes the combination of skeletal stem cells (SSCs) and impaction bone grafting (IBG) for the treatment of patients with bone defects associated with avascular necrosis of the femoral head. SSCs and milled allograft were impacted into necrotic bone in the femoral heads of four patients. Three patients remained asymptomatic at 22-44 month follow-up, but one patient has required total hip replacement (both hips). This has allowed retrieval of the femoral heads, which were analysed structurally and functionally by μCT, histology and mechanical testing. A central channel of impacted bone was found in the femoral heads, which displayed a mature trabecular micro-architecture. The impacted bone was denser than the surrounding trabecular bone, as strong in compression and with histological micro-architecture comparable to that of trabecular bone. Analysis of the retrieved femoral head samples has demonstrated that this tissue-engineering strategy regenerates bone that is both structurally and functionally analogous to normal trabecular bone. SSCs, together with IBG, have proved an effective treatment for avascular necrosis of the femoral head and offer significant potential for the broader spectrum of bone defects.

Translational hurdles for tissue engineering: an in vitro analysis of commonly used local anaesthetics on skeletal stem cell survival

When transferring tissue regenerative strategies involving skeletal stem cells to human application, consideration needs to be given to factors that may affect the function of the cells that are transferred. Local anaesthetics are frequently used during surgical procedures, either administered directly into the operative site or infiltrated subcutaneously around the wound. The aim of this study was to investigate the effects of commonly used local anaesthetics on the morphology, function and survival of human adult skeletal stem cells. Cells from three patients who were undergoing elective hip replacement were harvested and incubated for two hours with 1% lidocaine, 0.5% levobupivacaine or 0.5% bupivacaine hydrochloride solutions. Viability was quantified using WST-1 and DNA assays. Viability and morphology were further characterised using CellTracker Green/Ethidium Homodimer-1 immunocytochemistry and function was assessed by an alkaline phosphatase assay. An additional group was cultured for a further seven days to allow potential recovery of the cells after removal of the local anaesthetic. A statistically significant and dose dependent reduction in cell viability and number was observed in the cell cultures exposed to all three local anaesthetics at concentrations of 25% and 50%, and this was maintained even following culture for a further seven days. This study indicates that certain local anaesthetic agents in widespread clinical use are deleterious to skeletal progenitor cells when studied in vitro; this might have relevance in clinical applications.

Tantalum trabecular metal - addition of human skeletal cells to enhance bone implant interface strength and clinical application

The osteo-regenerative properties of allograft have recently been enhanced by addition of autogenous human bone marrow stromal cells (HBMSCs). Limitations in the use of allograft have prompted the investigation of tantalum trabecular metal (TTM) as a potential alternative. TTM is already in widespread orthopaedic use, although in applications where there is poor initial stability, or when TTM is used in conjunction with bone grafting, initial implant loading may need to be limited. The aim of this study was to evaluate the osteo-regenerative potential of TTM with HBMSCs, in direct comparison to human allograft and autograft. HBMSCs were cultured on blocks of TTM, allograft or autograft in basal and osteogenic media. Molecular profiling, confocal and scanning electron microscopy (SEM) and biochemical assays were used to characterize cell adherence, proliferation and phenotype. Mechanical testing was used to define the tensile characteristics of the constructs. HBMSCs displayed adherence and proliferation throughout TTM, evidenced by immunocytochemistry and SEM, with significant cellular ingrowth and matrix production through TTM. In contrast to cells cultured with allograft, cell proliferation assays showed significantly higher activity with TTM (p < 0.001), although molecular profiling confirmed no significant difference in expression of osteogenic genes. In contrast to acellular constructs, mechanical testing of cell-TTM constructs showed enhanced tensile characteristics, which compared favourably to cell-allograft constructs. These studies demonstrated the ability of TTM to support HBMSC growth and osteogenic differentiation comparable to allograft. Thus, TTM represents an alternative to allograft for osteo-regenerative strategies, extending its clinical applications as a substitute for allograft.

Supercritical CO2 fluid-foaming of polymers to increase porosity: a method to improve the mechanical and biocompatibility characteristics for use as a potential alternative to allografts in impaction bone grafting?

Disease transmission, availability and cost of allografts have resulted in significant efforts to find an alternative for use in impaction bone grafting (IBG). Recent studies identified two polymers with both structural strength and biocompatibility characteristics as potential replacements. The aim of this study was to assess whether increasing the polymer porosity further enhanced the mechanical and cellular compatibility characteristics for use as an osteogenic biomaterial alternative to allografts in IBG. Solid and porous poly(DL-lactide) (P(DL)LA) and poly(DL-lactide-co-glycolide) (P(DL)LGA) scaffolds were produced via melt processing and supercritical CO(2) foaming, and the differences characterized using scanning electron microscopy (SEM). Mechanical testing included milling and impaction, with comparisons made using a shear testing rig as well as a novel agitation test for cohesion. Cellular compatibility tests for cell number, viability, and osteogenic differentiation using WST-1 assays, fluorostaining, and ALP assays were determined following 14 day culture with skeletal stem cells. SEM showed excellent porosity throughout both of the supercritical-foam-produced polymer scaffolds, with pores between 50 and 200 μm. Shear testing showed that the porous polymers exceeded the shear strength of allograft controls (P<0.001). Agitation testing showed greater cohesion between the particles of the porous polymers (P<0.05). Cellular studies showed increased cell number, viability, and osteogenic differentiation on the porous polymers compared to solid block polymers (P<0.05). The use of supercritical CO(2) to generate porous polymeric biodegradable scaffolds significantly improves the cellular compatibility and cohesion observed compared to non-porous counterparts, without substantial loss of mechanical shear strength. These improved characteristics are critical for clinical translation as a potential osteogenic composite for use in IBG.

Skeletal stem cells and bone regeneration: Translational strategies from bench to clinic

Clinical imperatives for new bone to replace or restore the function of traumatized or bone lost as a consequence of age or disease has led to the need for therapies or procedures to generate bone for skeletal applications. Tissue regeneration promises to deliver specifiable replacement tissues and the prospect of efficacious alternative therapies for orthopaedic applications such as non-union fractures, healing of critical sized segmental defects and regeneration of articular cartilage in degenerative joint diseases. In this paper we review the current understanding of the continuum of cell development from skeletal stem cells, osteoprogenitors through to mature osteoblasts and the role of the matrix microenvironment, vasculature and factors that control their fate and plasticity in skeletal regeneration. Critically, this review addresses in vitro and in vivo models to investigate laboratory and clinical based strategies for the development of new technologies for skeletal repair and the key translational points to clinical success. The application of developmental paradigms of musculoskeletal tissue formation specifically, understanding developmental biology of bone formation particularly in the adult context of injury and disease will, we propose, offer new insights into skeletal cell biology and tissue regeneration allowing for the critical integration of stem cell science, tissue engineering and clinical applications. Such interdisciplinary, iterative approaches will be critical in taking patient aspirations to clinical reality.

Osteosarcoma metastasising to the duodenum and pancreas

The incidence of metastatic osteosarcoma is increasing because of improved results following multi-agent chemotherapy and resection of the primary tumour. Metastases occur most commonly in the lungs, whereas bowel metastases are rare. We describe a 25-year-old female who presented with melaena six years after successful resection of an osteosarcoma of her right femur, and one year after resection of a solitary pulmonary metastasis. Imaging revealed a lesion arising within both the duodenum and the pancreas for which a Whipple's pancreatoduodenectomy was carried out, achieving complete resection. Histological examination confirmed the diagnosis of metastatic osteosarcoma. We believe this is only the second such case reported. At 11 months post-operatively she had no detectable disease. Although rare, osteosarcoma can metastasise to the intestine. The surgeon must be aware of this complication, and that bowel metastases are potentially resectable.

Missed opportunities? Management of patients with alcohol problems in a surgical ward

Patients with alcohol problems necessitate treatment with counselling, and hospital admission for alcohol related complaints presents an ideal opportunity for this. This paper aims to examine the management of patients with alcohol related complaints on a surgical ward. Patients were interviewed to analyse the extent of their alcohol problem and counselling received, and doctors completed a questionnaire about counselling they offered. Forty seven out of 435 patients (10.8%) had alcohol related complaints; 28 of these 47 were alcohol dependent; 22 out of 28 alcohol dependent patients were not spoken to about their alcohol consumption on this admission. Thirteen doctors responsible for hospital admissions completed the questionnaire: although an alcohol history was almost always taken, counselling was rarely offered. In conclusion, the management of patients with alcohol problems in the emergency admission was sub-optimal. The treatment most needed was counselling, and this ideal opportunity for intervention was almost always missed.