Two-stage revision arthroplasty for PJI may make use of an antibiotic-loaded cement spacer (ACS), as successful long- term prevention of reinfection have been reported using this technique.[i] However, there is little data on systemic complications of high-dose antibiotic spacers. Acute kidney injury (AKI) is of clinical significance, as the drugs most commonly utilized, vancomycin and aminoglycosides, can be nephrotoxic. We intended to determine the incidence of AKI in patients that underwent staged revision arthroplasty with an ACS, as well as to identify potential predisposing risk factors for the disease. Local databases of six different orthopaedic surgeons were retrospectively reviewed for insertion of either a static or articulating antibiotic cement spacer by from 2007–2017. Dose of antibiotic powder implanted, as well as IV antibiotic used, was collected from operative records. Demographics, comorbidities, and preoperative and postoperative creatinine and hemoglobin values were recorded from the EHR. AKI was defined by a more than 50% rise in serum creatinine from preoperative baseline to at least 1.4 mg/dL, as described by Menge et al.[ii] Variables were analyzed for the primary outcome of AKI within the same hospital stay as insertion of the ACS. Categorical variables were analyzed with Chi-Square test, and continuous variables with univariate logistic regression.INTRO
METHODS
This study aims to identify recent trends in discharge disposition following bilateral total knee arthroplasty (TKA) as well as factors that predispose patients to enter inpatient rehabilitation facilities (IRF) or skilled nursing facilities (SNF) versus home-rehabilitation (HR). The goal was to identify risk factors that predispose prolonged hospital stays and identify changes in management over time that may be responsible for decreased length of stay (LOS) and a HR program. A retrospective cohort study design was used to collect and analyze clinical and demographic data for 404 consecutive bilateral primary total knee arthroplasty (TKA) procedures. Patients who underwent elective primary bilateral total knee arthroplasty from 2011 to 2016 were identified from hospital records at a single institution. Clinical and demographic data including sex, age, and disposition were analyzedBACKGROUND
METHODS
High-dose antibiotic cement spacers are commonly used to treat prosthetic joint infections following knee arthroplasties. Several clinical studies have shown a high success rate with antibiotic cement spacers, however there is little data on the systemic complications of high-dose antibiotic spacers, particularly acute kidney injury (AKI). This study aims to determine the incidence of AKI and identify risk factors predisposing patients undergoing staged revision arthroplasty with antibiotic cement spacers. A single-institution, retrospective review was used to collect and analyze clinical and demographic data for patients who underwent staged revision total knee arthroplasty with placement of an antibiotic-impregnated cement spacer from 2006 to 2016. A search was made through specific procedure (DRG) and diagnostic (CD) codes. Baseline descriptive data were collected for all patients including age, sex, medical comorbidities, type and quantity of antibiotics used in the cement spacer, pre- and postoperative hemoglobin (Hg), BMI, smoking status, peak creatinine levels, and random vancomycin levels. Acute kidney injury was defined as a more than 50% rise in serum creatinine from a preoperative baseline within 90 days postoperatively.BACKGROUND
METHODS
The aim of this study was to produce estimates of specificity and predictive value of presenting symptoms and signs of paediatric bone cancer, a rare and frequently misdiagnosed condition, to aid clinical decision-making in primary care. A systematic literature review plus questionnaire to primary care physicians were carried out to determine frequency of bone cancer symptoms in both cancer and the benign conditions as which cancer is misdiagnosed. Literature sources – Ovid MEDLINE (1950-May 2008), EMBASE (1980-May 2008) and AMED (Allied and Alternative Medicine) (1985-May 2008). Literature review methods – We included systematic reviews, cohort studies or case series (where n ≥ 10), reporting frequency of symptoms and signs at initial presentation, as originally recorded in case notes or observed by the authors, in subjects aged 0–18 years. Disease incidence data was taken from retrospective and prospective studies from 1980 onwards which recorded incidence over a defined time period, in a large pre-defined population within Europe, North America or Australia. Questionnaire respondents – 32 general practitioners and paediatric Accident & Emergency physicians throughout Scotland and England. Positive predictive values (PPVs) for bone cancer symptoms range from 0.003 to 0.034% (percentage of children presenting with symptom who have cancer). Specificity (percentage of children without cancer who do not have the symptom) varies considerably between symptoms and ranges from 24% (tenderness) to 95% (weight loss). Specificity can be improved by looking for combinations of symptoms. Weight loss and fever are the features with both highest specificity and highest PPV. Bone cancer symptoms, even those with high specificity for cancer, have low positive predictive value. We suggest that diagnosis based on initial presentation to primary care is intrinsically difficult and that delay in diagnosis is not unreasonable if it is to make use of time as a diagnostic aid.
There is renewed concern surrounding the potential for corrosion at the modular head-neck junction to cause early failure in modern hip implants. Although taper corrosion involves a complex interplay of many factors, previous studies have correlated decreasing flexural rigidity of the femoral trunnion with an increased likelihood of corrosion at retrieval. A multicenter retrieval analysis of 85 modular femoral stems was performed to calculate the flexural rigidity of various femoral trunnions. Stems were implanted between 1991–2012 and retrieved between 2004–2012. There were 10 different taper designs from 16 manufacturers. Digital calipers were used to measure taper geometries by two independent observers. Mean flexural rigidity was 262 Nm2, however there was a wide range of values among the various stems spanning nearly an order of magnitude between the most flexible (80 Nm2) and most rigid (623 Nm2) trunnions, which was due in part to the taper geometry and in part to the material properties of the base alloy. There was a modest but significant negative correlation between flexural rigidity of the trunnion and release date of the stem. This wide variability in flexural rigidity may predispose particular stem designs to an increased risk of corrosion at the modular head-neck taper, and may in part explain why taper corrosion is being seen with increasing frequency in modern hip arthroplasty.
Advances in the performance and longevity of total joint arthroplasty (TJA) have been enabled by related progress in implant materials, device designs, and surgical techniques. Successful TJA also depends upon adequate bone quality to provide an enduring mechanical foundation. Bone quality can be defined as the ability to repetitively withstand physiologically-relevant loads without excess deformation or fracture. It is now recognized that bone quality encompasses more than just material quantity, i.e. densitometrically-measured bone mass. Bone quality is also determined by: material composition and arrangement, cortical and cancellous structure, and extent of microdamage. These properties, together with the appropriate mass, confer bone with the biomechanical competence needed to meet the repetitive load-bearing demands imposed by total joint implants. The need for TJA continues to increase in the aging global baby-boomer population. Unfortunately, this group is also experiencing increases in related comorbidities including: osteoporosis, kidney dysfunction, and diabetes, among others. Collectively these three comorbidities afflict more than 74 million Americans, and each is increasing at 2–8% annually. More importantly, each of these comorbidities negatively affects bone quality through alterations in bone turnover independent of bone mass changes commonly associated with these diseases. Specifically, alterations in bone turnover result in abnormal mineral-to-matrix ratios as measured by Fourier transform infra-red (FTIR) spectroscopy (Fig. 1) and altered Young's moduli (shape-independent resistance to deformation) as measured by nanoindentation (Fig. 2). These parameters are related to bones' fracture toughness and load-bearing capabilities, respectively. Also, low bone turnover is associated with mechanically important structural changes, i.e., decreased trabecular thickness (Fig. 3), cortical thickness and cancellous volume. Furthermore, low bone turnover may result in reducing the repair rate of physiologically – induced bone microdamage. This may lead to increases in the number or length of bone cracks, crack coalescence, and ultimately reduced energy needed for fracture. Therefore, patients needing TJA who also have comorbidities associated with abnormal bone quality are at risk for inferior arthroplasty results. Recognition and treatment of the TJA-relevant biomechanical implications of these comorbidities may help improve outcomes.
There is a high rate of forearm deformity in patients with hereditary multiple exostoses (HME), and a quarter of patients acquire a dislocated radial head due to disproportionate ulnar shortening. One-hundred and six patients with HME aged 15 years or older were identified from a prospective database. Flexion and extension of the elbow and wrist, and supination and pronation of the forearm was measured. The number of exostoses affecting the proximal and distal radius and ulna were recorded. Proportional ulna length was calculated as a percentage of the patients measured height ([ulna length/height] × 100). More than 70% of patients were affected by exostoses of the forearm, of which the distal radius was the commonest site to be affected (73%). One in seven patients had a dislocated radial head, which was associated with proportional ulna shortening (p<0.001). Both radial head dislocation (p<0.001) and proportional ulna shortening (p<0.001) were confirmed to be independent predictors of forearm motion on multivariable regression analysis. In conjunction with other predictors these could be used to calculate ROM of the forearm. In addition proportional ulna length was also an independent predictor of radial head dislocation (p<0.001). Proportional ulna length could be used as a tool to identify patients at risk of diminished forearm motion and radial head dislocation during childhood, who could be monitored clinically and radiographically, and surgical intervention could be offered before deterioration in function and dislocation of the radial head occurs.
In previous small series, some authors have suggested a difference between re-fractures through immature callus and remodelled bone. We aimed to determine whether different fracture patterns occur in early and late re-fractures of paediatric forearm bones. Notes and radiographs of 77 forearm re-fractures from children aged 2–14 years were retrieved from our institution's radiographic database. Children treated surgically at initial presentation and re-fractures beyond one year were excluded. A control group of 100 forearm fractures without complication was used for comparison. Statistical analysis used chi-square and unpaired t-tests and statistically significant results were based on a two-tailed p-value <0.05Aim
Methods
Fractures of the scaphoid are uncommon in the paediatric population. Despite their rarity a significant number of children are referred to the fracture clinic for a suspected scaphoid fracture. The aim of this study is to report on the incidence and pattern of injury of the paediatric scaphoid fracture and present a new classification. An analysis of all paediatric scaphoid fractures treated in the Royal Hospital for Sick Children, Edinburgh (age up to 14 years old) over a five year period. The case notes, radiographs and were applicable MRI scan for these patients were reviewed. The clinical information recorded included the dominant hand, mechanism of injury, clinical features on examination, type of cast and length of period, stiffness following cast removal and evidence of delayed or non union. Each radiograph was analysed independently and fracture classified according to a new classification system.Background
Methods
The pathophysiology of high failure rates following rotator cuff tendon repairs, particularly massive tears, is not fully understood. Collagen structural changes have been shown to alter tendon thermal and mechanical properties. Thermal changes in small biopsies, detected by differential scanning calorimetry (DSC) can help to quantify collagen structural differences in torn rotator cuff tendons. This study aimed to form a quantitative rather than qualitative assessment, of whether differences in collagen structure and integrity existed between small biopsies of normal, small and massive rotator cuff tears using DSC. Thermal properties were measured for 27 human biopsies taken intra-operatively from normal, small, and massive rotator cuff tendon tears. 3 samples were taken from each patient and subjected to a modulated temperature ramp between 20–80°C at a rate of 2°C per minute with 0.318°C amplitude. The melting temperature (TM) is proposed to represent amide-amide hydrogen bond breakage and resulting protein backbone mobility. Denaturing temperature (TD) reportedly corresponds to the temperature at which the proteins fall out of solution. Denaturation enthalpy (H) should correlate with the amount of triple helical structure. Based upon a pre-study power calculation, this study had 90% power to detect a 10% difference in melting and denaturation temperature between groups with alpha=0.05. 1 specimen per patients was also frozen and cryosectioned and polarised light microscopy was used for quantitative validation. The effect of tear size on heat related parameters were performed using a one-way ANOVA test. A student's unpaired t-test was used to search for differences between individual groups (small tears, massive tears and normal tendons).Introduction
Methods
Metastatic osteosarcoma is seen in 10-20% of patients at initial presentation with the lung the most common site of metastasis. Historically, prognosis has been poor. We studied trends in survival in our small developed nation and aimed to identify correlations between the survival rate and three factors: newer chemotherapy, advances in radiological imaging and a more aggressive approach adopted by cardiothoracic surgeons for lung metastases. Our national bone tumour registry was used to identify patients at the age of 18 or under, who presented with metastatic disease at initial diagnosis between 1933 and 2006. There were 30 patients identified. Kaplan-Meier analysis was used to determine survival rates and univariate analysis was performed using the Cox regression proportional hazards model. Median survival has improved over the last 50 years; highlighted by the ‘Kotz’ eras demonstrating incremental improvement with more effective chemotherapy agents (p=0.004), and a current 5-year survival of 16%. Aggressive primary and metastatic surgery also show improving trends in survival. Three patients have survived beyond five years. The introduction of computerised tomography scanning has led to an increase in the prevalence of metastases at initial diagnosis. Metastatic osteosarcoma remains with a very poor prognostic factor, however, aggressive management has been shown to prolong survival.
Metastatic osteosarcoma is seen in 10-20% of patients at initial presentation with the lung the most common site of metastasis. Historically, prognosis has been poor. We studied trends in survival in our small developed nation and aimed to identify correlations between the survival rate and three factors: newer chemotherapy, advances in radiological imaging and a more aggressive approach adopted by cardiothoracic surgeons for lung metastases. Our national bone tumour registry was used to identify patients at the age of 18 or under, who presented with metastatic disease at initial diagnosis between 1933 and 2006. There were 30 patients identified. Kaplan-Meier analysis was used to determine survival rates and univariate analysis was performed using the Cox regression proportional hazards model. Median survival has improved over the last 50 years; highlighted by the ‘Kotz’ eras demonstrating incremental improvement with more effective chemotherapy agents (p=0.004), and a current 5-year survival of 16%. Aggressive primary and metastatic surgery also show improving trends in survival. Three patients have survived beyond 5 years. The introduction of computerised tomography scanning has led to an increase in the prevalence of metastases at initial diagnosis. Metastatic osteosarcoma remains with a very poor prognostic factor, however, aggressive management has been shown to prolong survival.
High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA). The shear properties of four RCT repair grafts were measured (Restore, GraftJacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G') as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations. A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn's multiple comparison test.Background
Methods
Improved understanding of the biomechanics and biology of rotator cuff tendons (RCT) may help reduce high re-rupture rates following repairs, particularly amongst larger tears. This study aims to use novel methods for quantitatively determining differences in the mechanical and thermal properties of intact healthy RCTs compared to torn ‘diseased’ tendons. A common problem in the mechanical testing of small tendon samples is that stress risers at the clamp-tendon interface can obscure measurements. As the shoulder is subject to shear, tension and compression, we developed a novel solution using Dynamic Shear Analysis (DSA), a form of rheology which studies material deformation. As collagen is the main component of RCT, the structure and mechanical properties may be affected by collagen conformational changes. Both dermis and rat tail tendon with increased collagen cross-linking exhibit stronger mechanical properties. Thermal changes detected by differential scanning calorimetry (DSC) can help to quantify collagen structural differences in torn RCT, and has been previously used to study muscle, cartilage and vertebral discs. There were 79 tears (mean age 65.2 years), which were classified according to the size of the tear as small, medium, large and massive. Two separate 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression. The storage modulus (G') was calculated and used as an indicator of mechanical integrity. 18 control tendon specimens were obtained from patients aged between 22-89 years (mean age 58.8 years) during shoulder hemiarthroplasties and stabilisations. Additionally 7 normal, 7 small and 7 massive frozen specimens were thermally characterized. 3 samples per patient were heated between 20-80oC in hermetically sealed vessels. Useful thermal parameters were measured such as the melting temperature (TM) which apparently represents breaking of the amide-amide bonds and protein chains mobility, the denaturation temperature (TD) which supposedly corresponds to proteins falling out of solution and the denaturation enthalpy (ΔH) which reflects the relative amount of triple helical structure. Healthy tendons had a significantly higher modulus than torn tendons, indicating that torn tendons are mechanically weaker than normal tendons (p = 0.032). Normal tendons had significantly higher mean shear modulus than tendons with small and massive tears (p<0.01). Overall there was a negative correlation between moduli and severity of tendon tear (r = −0.698, p=0.189). The moduli did not significantly correlate with age, sex, hand dominance, or length of preservation in formalin. Massive RCT tears had significantly higher TM and TD when compared to normal RCT (p < 0.05), unlike small RCT tears. No significant difference was detected between the denaturation enthalpy of the different RCT groups. This case control study has demonstrated that normal RCTs have a significantly higher modulus than torn tendons, indicating that torn tendons have less mechanical integrity. Our study further demonstrated a trend between increasing tear size and decreasing mechanical integrity. This study has also demonstrated differences in some of the thermal properties of normal and torn RCTs. These are likely due to collagen structural changes. A decrease in the denaturation temperature of torn tendons, suggests that the material is intrinsically less stable. Torn tendons with reduced storage modulus and collagen integrity may be less able to withstand mechanical loads following repair. This pilot study provides some preliminary insight into the mechanisms that may contribute to, or represent adaptations to high rates of failure of RCT repairs.
Supracondylar fractures of the humerus have historically been treated as an emergency case and operated on at the earliest opportunity. We undertook a study to examine whether surgical timing affects the need for open reduction or peri-operative complications in the type III injuries. Between August 1995 and August 2004, 534 patients presented and were referred to our unit with these fractures. Those with closed, type III injuries without vascular compromise were selected (171 patients). These were divided into 2 groups: those undergoing surgery less than 8 hours from presentation (126 patients) and those undergoing surgery more than 8 hours from presentation (45 patients). The two major differences between the two groups were: the delayed group were more likely to undergo open reduction (33.3% v 11.2%, p<0.05) and the mean length of the surgical procedure was increased (105.1 minutes v 69.2 minutes, p<0.05). Delay in treatment of the type III supracondylar fractures is associated with an increased need for open reduction and a longer procedure. We would recommend treating these injuries at the earliest opportunity.
This study investigates the experience of one treatment centre with routine surveillance MRI following excision of sarcoma. Casenotes, MRI and histology reports for fifty-nine patients were reviewed. The primary outcome was the presence of local tumour recurrence and whether this was identified on surveillance or interval scanning. Forty-eight patients had a diagnosis of soft tissue sarcoma, the remaining 11 a primary bone tumour. Fifteen patients had local recurrence (25%). Eight were identified on surveillance scan, and the remaining 7 required interval scans. Surveillance scanning has a role in the early detection of local recurrence of bone and soft tissue sarcoma.
Endoprosthetic replacement of the pelvis is one of the most challenging types of limb-salvage surgery, with a high rate of complications. In an attempt to reduce this and build greater versatility into the reconstruction process, a new type of pelvic endoprosthesis was developed in 2003, based on the old McKee-Farrar prosthesis. This study reviews the outcomes in 27 patients who had an ice-cream cone pelvic prosthesis inserted at two different specialist bone tumour centres in the United Kingdom over the past six years. The indications for treatment included primary bone tumours in 19 patients and metastatic disease in two, and six implants were inserted following failure of a previous pelvic reconstruction. Most of the patients had a P2+P3 resection as classified by Enneking, and most had resection of the ilium above the sciatic notch. The mean age of the patients at operation was 49 years (13 to 81). Complications occurred in ten patients (37.0%), of which dislocation was the most common, affecting four patients (14.8%). A total of three patients (11.1%) developed a deep infection around the prosthesis but all were successfully controlled by early intervention and two patients (7.4%) developed a local recurrence, at the same time as widespread metastases appeared. In one patient the prosthesis was removed for severe pain. This method of treatment is still associated with high morbidity, but early results are promising. Complications are diminishing with increasing experience.
in the immature group, 6 patients (ex 35; 17%) developed a further manifestation of the condition (2 had recurrences at same site; 2 developed a distinct focus in bone; 1 developed a distinct soft tissue lesion causing spinal cord compression; 1 developed diabetes insipidus), in the mature group, 3 patients (ex 26; 12%) developed a distinct focus in bone but there was no other recurrence/progression.
