[Promoting Young Talents in Trauma Surgery through Students-On-Call]

BACKGROUND

Due to restrictions on admission to medical school, changing claims to an optimized work-life balance and occupational perspectives, surgical professions in particular are struggling with strategies to motivate young academics. Surgical disziplines aim towards a profound transfer of knowledge and pique student's interest by ensuring a sustainable education at university.

OBJECTIVES

The goal of this study was to evaluate a Students-On-Call System (SOCS) and to identify a financial benefit.

MATERIALS AND METHODS

In this study the SOCS was compared pre-/postevaluation using questionnaires and the supporting X‑rays within a curricular teaching module of orthopedic trauma surgery, with students in the fourth semester of specialism and those in the practical semester at medical school.

RESULTS

The students of SOCS showed significantly better results prior to the course and afterwards than the two other groups. By establishing SOCS medical students get involved into the treatment of emergency patients in the trauma resuscitation unit (TRU) and operating room (OR). Students get the chance to enhance their comprehension of diagnostics, therapy and decision making in surgical context. This highly valuable traineeship combines a minimized teaching effort with an effective motivation of young academcis for the surgical profession. A SOCS has reduced the workload of medical colleagues. Establishing SOCS spare the residents being on call and results in reduced costs of 23,659.86 Euro per year.

CONCLUSION

The results presented show that the SOCS leads to an excellent cost-benefit balance, which has been established in multiple surgical departments at the medical school of the University of Göttingen. Apart from practice-oriented surgical teaching, the SOCS is a way of promoting successful young talent saving resources in the medical on-call services.

Direct comparison of F-l 8-FDG PET and ultrasound in the follow-up of patients with squamous cell cancer of the head and neck

Aim: The objective of this study was to compare screening ultrasound (US) obtained in patients with squamous cell carcinoma of the head and neck with F-l 8-FDG PET and to evaluate if US obtained before F-l 8-FDG PFT has the potential to enhance patient management by the detection of additional lesions. Method: 28 patients were prospectively included in the study (7 females and 21 males; range: 28-82 years). All had one follow-up examination after surgical treatment and/or radiotherapy using a combination of US and F-l 8-FDG PET on the same day (6-35 months after the end of treatment). Outcome was determined by either biopsyproven cancer recurrence or negative clinical follow-up for additional 6 months after this examination. Results: Regarding only the regions of the neck evaluated with both methods, US detected 25 suspect lesions vs. 9 lesions detected by F-l 8-FDG PET. Descriptive statistical analysis showed better sensitivity, specificity and accuracy of F-l 8-FDG PET. Only in 3 patients a lesion was detected in the same anatomical region using both methods. One patient was false positive with both methods. In another patient US detected a calcified right carotid artery plaque that lead to surgical therapy. Conclusion: F-l 8-FDG PET is better for the detection of clinically relevant lesions in the follow-up of patients with squamous cell carcinoma of the head and neck. In this study, the additional value of morphological information obtained by screening US performed before the PET scan is limited. US may not be a suitable test to improve interpretation of PET examinations.

Bone bruise als Sonderfall des Knochenmarködems

Der traumatische bone bruise ist eine Sonderform des Knochenmarködems. Als Ursache werden trabekuläre Mikrofrakturen, Einblutungen, eine reaktive Hyperämie und Nekrosen bei intakter Kortikalis beschrieben. Der bone bruise wird auch als “footprint” des Verletzungs- bzw. Unfallmechanismus angesehen. Die Diagnostik erfolgt in der Regel durch MRT-Bildgebung. Bone bruise kann isoliert oder als Begleitverletzung auftreten und zeigt sich dann in verletzungstypischen Knochenarealen. Bone bruise ist häufig mit belastungsabhängigen Schmerzen assoziiert, jedoch sind auch asymptomatische Verläufe, besonders bei Sportlern, zu beobachten. Im Vordergrund der Therapie steht die Begleitverletzung. Bei isoliertem bone bruise erfolgt eine symptomatische Therapie mit Analgesie und Entlastung. Die Rückkehr zum vorherigen Aktivitätslevel beträgt durchschnittlich drei Monate. Veränderungen im MRT können auch über zwölf Monate hinaus anhalten. Eine Schädigung des über dem bone bruise befindlichen Gelenkknorpels gilt als sehr wahrscheinlich.

Cement augmentation versus extended dorsal instrumentation in the treatment of osteoporotic vertebral fractures: a biomechanical comparison

AIMS

Loosening of pedicle screws is a major complication of posterior spinal stabilisation, especially in the osteoporotic spine. Our aim was to evaluate the effect of cement augmentation compared with extended dorsal instrumentation on the stability of posterior spinal fixation.

MATERIALS AND METHODS

A total of 12 osteoporotic human cadaveric spines (T11-L3) were randomised by bone mineral density into two groups and instrumented with pedicle screws: group I (SHORT) separated T12 or L2 and group II (EXTENDED) specimen consisting of T11/12 to L2/3. Screws were augmented with cement unilaterally in each vertebra. Fatigue testing was performed using a cranial-caudal sinusoidal, cyclic (1.0 Hz) load with stepwise increasing peak force.

RESULTS

Augmentation showed no significant increase in the mean cycles to failure and fatigue force (SHORT p = 0.067; EXTENDED p = 0.239). Extending the instrumentation resulted in a significantly increased number of cycles to failure and a significantly higher fatigue force compared with the SHORT instrumentation (EXTENDED non-augmented + 76%, p < 0.001; EXTENDED augmented + 87%, p < 0.001).

CONCLUSION

The stabilising effect of cement augmentation of pedicle screws might not be as beneficial as expected from biomechanical pull-out tests. Lengthening the dorsal instrumentation results in a much higher increase of stability during fatigue testing in the osteoporotic spine compared with cement augmentation. Cite this article: Bone Joint J 2016;98-B:1099-1105.

A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis

Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome that involves an osteopetrosis-like sclerosis of the long bones and fibrous dysplasia-like cemento-osseous lesions of the jawbone. Although the genetic analysis of the respective patients has revealed mutations in the ANO5 gene as an underlying cause, there is still no established consensus regarding the bone status of GDD patients. We report a new case of GDD in a 13-year-old boy with recurrent diaphyseal fractures of the femur, in whom we identified a novel de novo missense mutation in the ANO5 gene, causing a p.Ser500Phe substitution at the protein level. After confirming the presence of GDD-characteristic abnormalities within the jaw bones, we focused on a full osteologic assessment using dual-energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and serum analyses. We thereby identified increased trabecular bone mass accompanied by elevated serum markers of bone formation and bone resorption. The high turnover bone pathology was further confirmed through the analysis of an iliac crest biopsy, where osteoblast and osteoclast indices were remarkably increased. Taken together, our findings provide evidence for a critical and generalized role of anoctamin-5 (the protein encoded by the ANO5 gene) in skeletal biology. As it is reasonable to speculate that modifying the function of anoctamin-5 might be useful for therapeutically activating bone remodeling, it is now required to analyze its function at a molecular level, for instance in mouse models. © 2016 American Society for Bone and Mineral Research.

Methodological Investigation of Perceived Structure of College Teaching across Two Cultures

4 multidimensional scaling analyses based on similarity ratings among 30 operational statements of college-level psychology teaching activities (stimuli) using samples of psychology students and teachers from the USA and Germany as raters resulted in 7 teaching factors common in varying degrees to both cultures and one in each culture with no counterpart in the other. The paired German-American factors ordered from most to least agreement in accordance with the proportion of their highly loaded stimuli held in common by corresponding factors across cultures were: Teacher (Lecturing) Dynamism, Dynamik des Vortragens; Classroom Administration, Durchsetzung der Ordnung; Information Dissemination, Ausgabe von Informationen; Knowledge Dissemination, Verarbeitung von Wissen; Advisory Guidance, Studentische Beratung; Environmental Regulation, Regulierung von Randbedingungen; Teacher-Student Feedback, Lehrer-Student Rueckmeldung; Control of Student Behavior, Verwendung von audiovisuellen Hilfsmitteln. Analyses of the degree of student-teacher agreement of factors within cultures resulted in a greater degree of within culture agreement than the degree of cross-cultural agreement shown among the 8 teaching factors. The clarity of the current results may be interpreted as indicating that the method employed possesses potential for establishing the degree of perceptual generality and meaningfulness of teaching performance criteria.

On-table decision-making in intracapsular hip fracture surgery: mid-term results of a pilot study

INTRODUCTION

At the present time, it is generally recommended to use hip replacement in dislocated fractures to avoid failure after internal fixation. A problem is that previous research has demonstrated that observers have problems in discriminating between dislocated and undislocated fractures. A possible solution to this problem would be to use arthroplasty in the majority of the cases. However, this also means that many fractures with the potential for uneventful healing would be replaced.

MATERIALS AND METHODS

In the current investigation, the mid-term outcome was recorded for patients with intracapsular hip fractures who were treated with either internal fixation or arthroplasty. A novel treatment algorithm was employed. After careful exclusion of cases with known risk factors for failure after internal fixation, a technique called on-table decision was used to identify suitable patients for internal fixation.

RESULTS

A total of 72 patients with intracapsular hip fractures were studied with a median follow-up time of 12 months (IQR 8-15.25 months). Nineteen (19) patients (26 %) were excluded in the selection process, leaving 53 (74 %) for on-table decision-making. Thirty patients (42 %) were identified as suitable for internal fixation and gave anatomically stable closed reductions. Two of these patients (7 %) exhibited non-unions and one (3 %) avascular necrosis.

CONCLUSIONS

The mid-term outcome after internal fixation is promising. The careful selection process may be helpful in identifying fracture patterns for which internal fixation may be considered as a safe and less invasive alternative to hip arthroplasty.

Histopathology of Submandibular Glands Removed for Sialolithiasis

We reviewed the clinical history of 48 consecutive patients who underwent submandibular gland removal for radiologically proven sialolithiasis. The specimens were examined by a pathologist blinded to the clinical data. A histopathologic classification into 1 of 3 grades was established by evaluating the degrees of atrophy, fibrosis, and inflammation. A correlation between the clinical and pathological variables was sought in order to define clinical variables that would predict abnormal submandibular glands that required extirpation. A significant percentage of the submandibular glands exhibited normal histologic findings. The patients with normal submandibular glands had a clinical evolution similar to that of other patients with severely damaged glands. The only clinical variable that correlated with increased histopathologic alteration was the patient's age. In view of the newly available diagnostic and therapeutic techniques for sialolithiasis, a conservative attitude to submandibular gland resection appears justified.

Periprosthetic fracture fixation in osteoporotic bone

Fixation techniques of periprosthetic fractures are far from ideal although the number of this entity is rising. The presence of an intramedullary implant generates its own fracture characteristics since stiffness is altered along the bone shaft and certain implant combinations affect load resistance of the bone. Influencing factors are cement fixation of the implant, intramedullary locking and extramedullary or intramedullary localization of the implant and the cortical thickness of the surrounding bone. Cerclage wires are ideally suited to fix radially displaced fragments around an intramedullary implant but they are susceptible to axial and torsional load. Screws should be added if these forces have to be neutralized. Stability of the screw fixation itself can be enhanced by embracement configuration around the intramedullary implant. Poor bone stock quality, often being present in metaphyseal areas limits screw fixation. Cement augmentation is an attractive option in this field to enhance screw purchase.

Intramedullary Mg2Ag nails augment callus formation during fracture healing in mice

Intramedullary stabilization is frequently used to treat long bone fractures. Implants usually remain unless complications arise. Since implant removal can become technically very challenging with the potential to cause further tissue damage, biodegradable materials are emerging as alternative options. Magnesium (Mg)-based biodegradable implants have a controllable degradation rate and good tissue compatibility, which makes them attractive for musculoskeletal research. Here we report for the first time the implantation of intramedullary nails made of an Mg alloy containing 2% silver (Mg2Ag) into intact and fractured femora of mice. Prior in vitro analyses revealed an inhibitory effect of Mg2Ag degradation products on osteoclast differentiation and function with no impair of osteoblast function. In vivo, Mg2Ag implants degraded under non-fracture and fracture conditions within 210days and 133days, respectively. During fracture repair, osteoblast function and subsequent bone formation were enhanced, while osteoclast activity and bone resorption were decreased, leading to an augmented callus formation. We observed a widening of the femoral shaft under steady state and regenerating conditions, which was at least in part due to an uncoupled bone remodeling. However, Mg2Ag implants did not cause any systemic adverse effects. These data suggest that Mg2Ag implants might be promising for intramedullary fixation of long bone fractures, a novel concept that has to be further investigated in future studies.

STATEMENT OF SIGNIFICANCE

Biodegradable implants are promising alternatives to standard steel or titanium implants to avoid implant removal after fracture healing. We therefore developed an intramedullary nail using a novel biodegradable magnesium-silver-alloy (Mg2Ag) and investigated the in vitro and in vivo effects of the implants on bone remodeling under steady state and fracture healing conditions in mice. Our results demonstrate that intramedullary Mg2Ag nails degrade in vivo over time without causing adverse effects. Importantly, radiographs, μCT and bone histomorphometry revealed a significant increase in callus size due to an augmented bone formation rate and a reduced bone resorption in fractures supported by Mg2Ag nails, thereby improving bone healing. Thus, intramedullary Mg2Ag nails are promising biomaterials for fracture healing to circumvent implant removal.

Isolated syndesmotic injuries in acute ankle sprains: diagnostic significance of clinical examination and MRI

PURPOSE

Acute ankle sprains are frequently accompanied by syndesmotic injuries. These injuries are often overlooked in clinical examinations. The aim of this study was (1) to evaluate the incidence of syndesmotic injuries in acute ankle sprains using MRI, (2) to determine the accuracy of common clinical diagnostic tests, (3) to analyse their inter-rater reliability, and (4) to evaluate the role of clinical symptoms in the diagnosis of syndesmotic injuries.

METHODS

A total of 100 patients with acute ankle sprain injury without associated fractures in plane radiographs were enrolled. The clinical assessment was performed by two independent examiners. Local findings, ankle ligament palpation, squeeze test, external rotation test, Drawer test, Cotton test, and the crossed-leg test (two examiners) were compared with MRI results (read by two blinded radiologists) as a reference standard.

RESULTS

Ninety-six participants (57% male) met the inclusion criteria. MRI detected a ruptured anterior inferior tibiofibular ligament (AITFL) in 14 patients (15%); 9 partial tears and 5 complete tears were evident. Evidence of pain at rest was found to predict syndesmotic injuries most accurately (p = 0.039). The palpation test over the proximal fibula produced the highest inter-rater correlation (κ = 0.65), but the lowest sensitivity for syndesmotic injuries of 8%. All other clinical tests demonstrated moderate to fair inter-rater reliabilities (κ = 0.37-0.52). Low sensitivity values were found with all clinical tests (13.9-55.6%).

CONCLUSION

In this study, clinical examination was insufficient to detect syndesmotic injuries in acute ankle sprains. MRI scanning revealed a syndesmotic lesion in 15% of patients. MRI scanning should be recommended in patients with ongoing pain at rest following ankle sprains.

LEVEL OF EVIDENCE

I.

Determination of Femoral Neck Angle and Torsion Angle Utilizing a Novel Three-Dimensional Modeling and Analytical Technology Based on CT Datasets

INTRODUCTION

Exact knowledge of femoral neck inclination and torsion angles is important in recognizing, understanding and treating pathologic conditions in the hip joint. However, published results vary widely between different studies, which indicates that there are persistent difficulties in carrying out exact measurements.

METHODS

A three dimensional modeling and analytical technology was used for the analysis of 1070 CT datasets of skeletally mature femurs. Individual femoral neck angles and torsion angles were precisely computed, in order to establish whether gender, age, body mass index and ethnicity influence femoral neck angles and torsion angles.

RESULTS

The median femoral neck angle was 122.2° (range 100.1-146.2°, IQR 117.9-125.6°). There are significant gender (female 123.0° vs. male 121.5°; p = 0.007) and ethnic (Asian 123.2° vs. Caucasian 121.9°; p = 0.0009) differences. The median femoral torsion angle was 14.2° (-23.6-48.7°, IQR 7.4-20.4°). There are significant gender differences (female 16.4° vs. male 12.1°; p = 0.0001). Femoral retroversion was found in 7.8% of the subjects.

CONCLUSION

Precise femoral neck and torsion angles were obtained in over one thousand cases. Systematic deviations in measurement due to human error were eliminated by using automated high accuracy morphometric analysis. Small but significant gender and ethnic differences were found in femoral neck and torsion angles.

A novel electromagnetic navigation tool for acetabular surgery

BACKGROUND

Acetabular fracture surgery is demanding and screw placement along narrow bony corridors remains challenging. It necessitates x-ray radiation for fluoroscopically assisted screw insertion. The purpose of this cadaver study was to evaluate the feasibility, accuracy and operation time of a novel electromagnetic navigation system for screw insertion along predefined acetabular corridors.

METHODS

A controlled laboratory study with a total of 24 electromagnetically navigated screw insertions was performed on 8 cadaveric acetabula. 3 peri-acetabular bony corridors (QSS, Quadrilateral Surface Screw; IAS, Infra-Acetabular Screw; PCS, Posterior Column Screw) were defined and screws were placed in a defined order without fluoroscopy. Operation time was documented. Postoperative CT scans were performed to analyse accuracy of screw placement.

RESULTS

Mean cadaver age was 70.4 ± 11.7. Successful screw placement was accomplished in 22 out of 24 (91.7%) cases. The overall mean time for all 3 acetabular screws was 576.6 ± 75.9s. All 3 complications occurred during the placement of the IAS due to an impassable narrow bony corridor. QSS mean length was 50 ± 5mm, IAS mean length was 85 ± 10mm and PCS mean length was 120 ± 5mm.

CONCLUSION

In this cadaver study the novel electromagnetic navigation system was feasible to allow accurate screw placement without fluoroscopy in defined narrow peri-acetabular bony corridors.

Extra- vs. intramedullary treatment of pertrochanteric fractures: a biomechanical in vitro study comparing dynamic hip screw and intramedullary nail

INTRODUCTION

Due to the demographic trend, pertrochanteric fractures of the femur will gain increasing importance in the future. Both extra- and intramedullary implants are used with good results in the treatment of these fractures. New, angular stable extramedullary implants promise increased postoperative stability even with unstable fractures. Additional trochanteric plates are intended to prevent secondary impaction, varisation and shortening of the fracture, as well as medialisation of the femoral shaft. The aim of this study was to perform a biomechanical comparison of both procedures regarding their postoperative stability and failure mechanisms.

MATERIALS AND METHODS

Twelve fresh-frozen human femurs were randomized into two groups based on the volumetric bone mineral density (vBMD). Standardized pertrochanteric fractures (AO31-A2.3) were generated and treated either with an angular stable dynamic hip screw (DHS) or an intramedullary nail (nail). Correct implant position and the tip-apex distance (TAD) were controlled postoperatively using X-ray. Specimens were mounted in a servohydraulic testing machine and an axial loading was applied according to a single-leg stance model. Both groups were biomechanically compared with regard to native and postoperative stiffness, survival during cyclic testing, load to failure, and failure mechanisms.

RESULTS

TAD, vBMD, and native stiffness were similar for both groups. The stiffness decreased significantly from native to postoperative state in all specimens (p < 0.001). The postoperative stiffness of both groups varied non-significantly (p = 0.275). The failure loads for specimens treated with the nail were significantly higher than for those treated with the DHS (8480.8 ± 1238.9 N vs. 2778.2 ± 196.8 N; p = 0.008).

CONCLUSIONS

Extra- and intramedullary osteosynthesis showed comparable results as regards postoperative stiffness and survival during cyclic testing. Since the failure load of the nail was significantly higher in the tested AO31-A2.3 fracture model, we conclude that intramedullary implants should be preferred in these, unstable, fractures.

Bone augmentation using a new injectable bone graft substitute by combining calcium phosphate and bisphosphonate as composite--an animal model

Objective

The aim of this study was to create a new injectable bone graft substitute by combining the features of calcium phosphate and bisphosphonate as a composite bone graft to support bone healing and to evaluate the effect of alendronate to the bone healing process in an animal model.

Material and method

In this study, 24 New Zealand white rabbits were randomly divided into two groups: a calcium phosphate alendronate group and a calcium phosphate control group. A defect was created at the proximal medial tibia and filled with the new created injectable bone graft substitute calcium phosphate alendronate or with calcium phosphate. Healing process was documented by fluoroscopy. To evaluate the potential of the bone graft substitute, the proximal tibia was harvested 2, 4, and 12 weeks after operation. Histomorphological analysis was focused on the evaluation of the dynamic bone parameters using the Osteomeasure system.

Results

Radiologically, the bone graft materials were equally absorbed. No fracture was documented. The bones healed normally. After 2 weeks, the histological analysis showed an increased new bone formation for both materials. The osteoid volume per bone volume (OV/BV) was significantly higher for the calcium phosphate group. After 4 weeks, the results were almost equal. The trabecular thickness (Tb.Th) increased in comparison to week 2 in both groups with a slight advantage for the calcium phosphate group. The total mass of the bone graft (KEM.Ar) and the bone graft substitute surface density (KEM.Pm) were consistently decreasing. After 12 weeks, the new bone volume per tissue volume (BV/TV) was still constantly growing. Both bone grafts show a good integration. New bone was formed on the surface of both bone grafts. The calcium phosphate as well as the calcium phosphate alendronate paste had been enclosed by the bone. The trabecular thickness was higher in both groups compared to the first time point.

Conclusion

Calcium phosphate proved its good potential as a bone graft substitute. Initially, the diagrams seem to show a tendency that alendronate improves the known properties of calcium phosphate as a bone graft substitute. The composite graft induced a good and constant new bone formation. Not only the graft was incorporated into the bone but also a new bone was formed on its surface. But we could not prove a significant difference between the grafts. Both implants proved their function as a bone graft substitute, but the bisphosphonate alendronate does not support the bone healing process sufficiently that the known properties of calcium phosphate as a bone graft substitute were improved in the sense of a composite graft. In this study, alendronate used as a bone graft in a healthy bony environment did not influence the bone healing process in a positive or negative way.

[Primary meningococcal infection of the knee. A rare cause of septic arthritis]

This article presents a case of primary septic arthritis of the knee due to serogroup C Neisseria meningitidis. A 19-year-old female presented to the emergency department with a painless but swollen knee joint which had started 2 days previously and fever (38 °C). The patient reported that she suddenly felt unwell 3 days ago and developed a rush at the same time which had almost disappeared when arrived at the emergency department. The patient was admitted to hospital and an antibiotic therapy was started with sulbactam and ampicillin. Initially, incubation of synovial fluid over the next 3 days did not result in detection of any pathogens; therefore, a reactive arthritis was assumed until Neisseria meningitidis was detected in cultures of the synovial fluid. Therapy was then switched to antibiotic therapy with ceftriaxon and arthroscopic irrigation was performed. The patient quickly recovered and was discharged from hospital after 14 days. This case example shows the difficulties of the clinical and microbiological diagnostics of a primary septic meningococcal arthritis; however, the treatment is relatively easy and mostly successful compared to other forms of bacterial joint infection.

Significance of clinical examination, CT and MRI scan in the diagnosis of posterior pelvic ring fractures

INTRODUCTION

Patients with a fracture in the anterior pelvic ring often simultaneously demonstrate pain in the posterior pelvic ring. The aim of the present prospective study was to assess the sensitivity of CT, MRI and clinical examination in the detection of fractures in the posterior pelvic ring in patients with fractures of the anterior pelvic ring diagnosed in conventional radiographs.

METHODS

Sixty patients with radiographic signs of an anterior pelvic ring injury were included in this prospective analysis. Following a focused clinical examination of the posterior pelvis, all patients underwent both a CT and then a MRI scan of their pelvis. Two board certified radiologists evaluated the CT and MRI scans independently. To estimate the presence of osteoporosis the Hounsfield units of the vertebral body of L5 were measured in each case.

RESULTS

Fifty-three women and seven men, with a mean age of 74.7+/-15.6 years were included into the study. A fracture of the posterior pelvic ring was found in fourty-eight patients (80%) patients using MRI. Fractures of the posterior pelvic ring would have been missed in eight cases (17%), if only CT had been used. Eighty-five percent of the patients with a posterior fracture had an osteoporosis. The majority of the cases suffered from a low energy trauma. Thirty-eight patients (83%) with positive clinical signs at the posterior pelvic ring actually had a fracture of the posterior pelvic ring in the MRI. The clinical examination proved to be equally effective to CT in detecting posterior pelvic ring fractures.

CONCLUSION

The significance of both, clinical examination and CT was confirmed in the detection of fractures in the posterior pelvic ring. MRI examination of the pelvis however, was found to be superior in detecting undislocated fractures in a cohort of patients with a high incidence of osteoporosis. Using MRI may be beneficial in select cases, especially when reduced bone density is suspected.

Comparison of conventional radiography and MDCT in suspected scaphoid fractures

AIM: To determine the diagnostic accuracy and radiation dose of conventional radiography and multidetector computed tomography (MDCT) in suspected scaphoid fractures.

METHODS: One hundred twenty-four consecutive patients were enrolled in our study who had suffered from a wrist trauma and showed typical clinical symptoms suspicious of an acute scaphoid fracture. All patients had initially undergone conventional radiography. Subsequent MDCT was performed within 10 d because of persisting clinical symptoms. Using the MDCT data as the reference standard, a fourfold table was used to classify the test results. The effective dose and impaired energy were assessed in order to compare the radiation burden of the two techniques. The Wilcoxon test was performed to compare the two diagnostic modalities.

RESULTS: Conventional radiography showed 34 acute fractures of the scaphoid in 124 patients (42.2%). Subsequent MDCT revealed a total of 42 scaphoid fractures. The sensitivity of conventional radiography for scaphoid fracture detection was 42.8% and its specificity was 80% resulting in an overall accuracy of 59.6%. Conventional radiography was significantly inferior to MDCT (P < 0.01) concerning scaphoid fracture detection. The mean effective dose of MDCT was 0.1 mSv compared to 0.002 mSv of conventional radiography.

CONCLUSION: Conventional radiography is insufficient for accurate scaphoid fracture detection. Regarding the almost negligible effective dose, MDCT should serve as the first imaging modality in wrist trauma.

What is the frequency of nerve injuries associated with acetabular fractures?

BACKGROUND

Acetabular fractures and surgical interventions used to treat them can result in nerve injuries. To date, only small case studies have tried to explore the frequency of nerve injuries and their association with patient and treatment characteristics. High-quality data on the risk of traumatic and iatrogenic nerve lesions and their epidemiology in relation to different fracture types and surgical approaches are lacking.

QUESTIONS/PURPOSES

The purpose of this study was to determine (1) the proportion of patients who develop nerve injuries after acetabular fracture; (2) which fracture type(s) are associated with increased nerve injury risk; and (3) which surgical approach was associated with the highest proportion of patients developing nerve injuries using data from the German Pelvic Trauma Registry. Two secondary aims were (4) to assess hospital volume-nerve-injury relationship; and (5) internal data validity.

METHODS

Between March 2001 and June 2012, 2236 patients with acetabular fractures were entered into a prospectively maintained registry from 29 hospitals; of those, 2073 (92.7%) had complete records on the endpoints of interest in this retrospective study and were analyzed. The neurological status in these patients was captured at their admission and at the discharge. A total of 1395 of 2073 (67%) patients underwent surgery, and the proportions of intervention-related and other hospital-acquired nerve injuries were obtained. Overall proportions of patients developing nerve injuries, risk based on fracture type, and risk of surgical approach type were analyzed.

RESULTS

The proportion of patients being diagnosed with nerve injuries at hospital admission was 4% (76 of 2073) and at discharge 7% (134 or 2073). Patients with fractures of the "posterior wall" (relative risk [RR], 2.0; 95% confidence interval [CI], 1.4-2.8; p=0.001), "posterior column and posterior wall" (RR, 2.9; CI, 1.6-5.0; p=0.002), and "transverse+posterior wall" fracture (RR, 2.1; CI, 1.3-3.5; p=0.010) were more likely to have nerve injuries at hospital discharge. The proportion of patients with intervention-related nerve injuries and that of patients with other hospital-acquired nerve injuries was 2% (24 of 1395 and 46 of 2073, respectively). They both were associated with the Kocher-Langenbeck approach (RR, 3.0; CI, 1.4-6.2; p=0.006; and RR, 2.4; CI, 1.4-4.3; p=0.004, respectively).

CONCLUSIONS

Acetabular fractures with the involvement of posterior wall were most commonly accompanied with nerve injuries. The data suggest also that Kocher-Langenbeck approach to the pelvic ring is associated with a higher risk of perioperative nerve injuries. Trauma surgeons should be aware of common nerve injuries, particularly in posterior wall fractures. The results of the study should help provide patients with more exact information on the risk of perioperative nerve injuries in acetabular fractures.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The role of inter-prosthetic distance, cortical thickness and bone mineral density in the development of inter-prosthetic fractures of the femur

It is becoming increasingly common for a patient to have ipsilateral hip and knee replacements. The inter-prosthetic (IP) distance, the distance between the tips of hip and knee prostheses, has been thought to be associated with an increased risk of IP fracture. Small gap distances are generally assumed to act as stress risers, although there is no real biomechanical evidence to support this.

The purpose of this study was to evaluate the influence of IP distance, cortical thickness and bone mineral density on the likelihood of an IP femoral fracture.

A total of 18 human femur specimens were randomised into three groups by bone density and cortical thickness. For each group, a defined IP distance of 35 mm, 80 mm or 160 mm was created by choosing the appropriate lengths of component. The maximum fracture strength was determined using a four-point bending test.

The fracture force of all three groups was similar (p = 0.498). There was a highly significant correlation between the cortical area and the fracture strength (r = 0.804, p <  0.001), whereas bone density showed no influence.

This study suggests that the IP distance has little influence on fracture strength in IP femoral fractures: the thickness of the cortex seems to be the decisive factor.

Cite this article: Bone Joint J 2014;96-B:1378–84.