The lower limbs of vehicle occupants are vulnerable to severe injuries during under vehicle explosions. Understanding the injury mechanism and causality of injury severity could aid in developing better protection. Therefore, we tested three different knee positions in standing occupants (standing, knee in hyper-extension, knee flexed at 20˚) of a simulated under‐vehicle explosion using cadaveric limbs in a traumatic blast injury simulator; the hypothesis was that occupant posture would affect injury severity. Skeletal injuries were minimal in the cadaveric limbs with the knees flexed at 20˚. Severe, impairing injuries were observed in the foot of standing and hyper‐extended specimens. Strain gauge measurements taken from the lateral calcaneus in the standing and hyper-extended positions were more than double the strain found in specimens with the knee flexed position. The results in this study demonstrate that a vehicle occupant whose posture incorporates knee flexion at the time of an under‐vehicle explosion is likely to reduce the severity of lower limb injuries, when compared to a knee extended position.
Improper soft-tissue balancing can result in postoperative complications after total knee arthroplasty (TKA) and may lead to early revision. A single-use tibial insert trial with embedded sensor technology (VERASENSE from OrthoSensor Inc., Dania Beach, FL) was designed to provide feedback to the surgeon intraoperatively, with the goal to achieve a “well-balanced” knee throughout the range of motion (Roche et al. 2014). The purpose of this study was to quantify the effects of common soft-tissue releases as they related to sensor measured joint reactions and kinematics. Robotic testing was performed using four fresh-frozen cadaveric knee specimens implanted with appropriately sized instrumented trial implants (geometry based on a currently available TKA system). Sensor outputs included the locations and magnitudes of medial and lateral reaction forces. As a measure of tibiofemoral joint kinematics, medial and lateral reaction locations were resolved to femoral anterior-posterior displacement and internal-external tibial rotation (Fig 1.). Laxity style joint loading included discrete applications of ± 100 N A-P, ± 3 N/m I-E and ± 5 N/m varus-valgus (V-V) loads, each applied at 10, 45, and 90° of flexion. All tests included 20 N of compressive force. Laxity tests were performed before and after a specified series of soft-tissue releases, which included complete transection of the posterior cruciate ligament (PCL), superficial medial collateral ligament (sMCL), and the popliteus ligament (Table 1). Sensor outputs were recorded for each quasi-static test. Statistical results were quantified using regression formulas that related sensor outputs (reaction loads and kinematics) as a function of tissue release across all loading conditions. Significance was set for p-values ≤ 0.05.Introduction
Methods
Recurrent patellar instability is common in young and active patients. Medial patellofemoral ligament (MPFL) reconstruction with a single bundle hamstring graft is one method of surgical treatment for this problem. This is a retrospective case series of patients who underwent MPFL reconstruction by a single specialist knee surgeon between January 2009 and July 2014. Data was collected prospectively for the purpose of service evaluation. Recorded data included gender, age, length of rehabilitation, complications, Knee Injury and Outcome Score (KOOS) and International Knee Documentation Score (IKDC). Data is expressed as mean (range). 108 knees (103 patients) were identified (56 female, 52 male) with a mean age of 24.5 years (12–58). Mean length of rehabilitation was 3.2 months (0–11 months). Three patients required further revision surgery for recurrent instability. KOOS and IKDC scores improved from 44 (4–86) and 38 (2–81), respectively before surgery, to 77 (49–100) and 69 (37–95) after rehabilitation. MPFL reconstruction with a single bundle hamstring graft produces a marked improvement in knee function with a low recurrence of instability.
Experimental testing reproducing activity specific joint-level loading has the potential to quantify structure-function relationships, evaluate intervention possibilities, perform device analysis, and quantify joint kinematics. Many recent technological advancements have been made in this field and inspire this study's aim to present a framework for the application of activity dependent tibiofemoral loading in a specific custom developed 6 degree of freedom (DOF) robotic test frame. This study demonstrates a pipeline wherein kinetic and kinematic data from subjects were collected in a gait lab, analyzed through musculoskeletal modeling techniques, and applied to cadaveric specimens in the robotic testing system in a real-time manner. This pipeline (Figure 1 blue dotted region) fits into a framework for synergistic development and refinement of arthroplasty techniques and devices. Gait lab kinetic and kinematic data for walking was collected from 5 subjects. Subject-specific musculoskeletal modeling was performed to determine 6 DOF active component joint loading (OpenSim version 2.4, Introduction
Methods
Characterising material properties of ligaments is essential in the analysis of human morbidity and mortality of low-speed sporting accidents, high-speed road traffic accidents, and very high-speed battlefield injuries. At lower strain rates the elastic modulus and ultimate stress increase relative to strain rate, although very high strain rate testing has not been performed to date. A porcine stifle joint lateral collateral ligament experiment was conducted that simulated the strain rates that occur during across a full range of different human knee ligament injuries. Tensile testing was performed at five strain rates, each an order of magnitude apart, in the range 100–104%/s. Seven specimens were tested at each rate. Three loading techniques were used: 1) screw-driven, 2) servo-hydraulic, 3) drop weight rig with tensile impact adaptor. Cross sectional area was measured by counting pixels on a standardized digital photograph of an alginate-paste cast of the mid-substance of each sample. Strain was measured directly from the mid-substance of each ligament by high-speed video extensometry. Stress-strain curves were produced and used to quantify the elastic modulus, failure strain and ultimate stress at each strain rate. Across the range of strain rates, elastic modulus increased from 288 to 905 MPa (p< 0.05), and ultimate stress increased from 39.9 to 77.3 MPa (p< 0.05). A relationship between strain rate and both, elastic modulus and ultimate stress was identified. Strain rate sensitivity was not observed at very fast strain rates. Ligament strength increases when strain rates are high. These data provide an explanation for very high strain rate failure of ligaments under extreme loading conditions, that can be considered protective of bone fracture, such as can be seen in traumatic through knee amputations in blast injuries.
Current military conflicts are characterised by the use of the Improvised Explosive Device (IED). Improvements in personal protection, medical care and evacuation logistics have resulted in increasing numbers of casualties surviving with complex musculoskeletal injuries, often leading to life-long disability. Thus, there exists an urgent requirement to investigate the mechanism of extremity injury caused by these devices in order to develop mitigation strategies. In addition, the wounds of war are no longer restricted to the battlefield; similar injuries can be witnessed in civilian centres following a terrorist attack. Key to mitigating such injuries is the ability to deconstruct the complexities of an explosive event into a controlled, laboratory-based environment. In this study, an anti-vehicle underbelly injury simulator, capable of recreating in the laboratory the impulse from an anti-vehicle (AV) explosion, is presented and characterised. Tests were then conducted to assess the simulator's ability to interact with human cadaveric legs. Two mounting conditions were assessed, simulating a typical seated and standing vehicle passenger using instrumented cadaveric lower limbs. This experimental device, will now allow us (a) to gain comprehensive understanding of the load-transfer mechanisms through the lower limb, (b) to characterise the dissipating capacity of mitigation technologies, and (c) to assess the biofidelity of surrogates.
In a recent publication, 4.6% of 6450 Coalition deaths over ten years were reported to be due to junctional bleeding. The authors suggested that some of these deaths could have been avoided with a junctional hemorrhage control device. Prospectively collected data on all injuries sustained in Afghanistan by UK military personnel over a 2 year period were reviewed. All fatalities with significant pelvic injuries were identified and analysed, and the cause of death established. Significant upper thigh, groin or pelvic injuries were recorded in 124 casualties, of which 92 died. Pelvic injury was the cause of death in 42; only 1 casualty was identified where death was at least in part due to a vascular injury below the inguinal ligament, not controlled by a tourniquet, representing <1% of all deaths. Twenty one deaths were due to vascular injury between the aortic bifurcation and the inguinal ligament, of which 4 survived to a medical facility. Some potentially survivable deaths due to exsanguination may be amenable to more proximal vascular control. We cannot substantiate previous conclusions that this can be achieved through use of a groin junctional tourniquet. There may be a role for more proximal vascular control of pelvic bleeding.
Counter-insurgency warfare in recent military operations has been epitomised by the use of Improvised Explosive Devices (IED) against coalition troops. Emerging patterns of skeletal fractures, limb amputations and organ injuries, which are caused by these weapons have been described over recent years. This paper describes a retrospective case series of knee dislocations caused by IEDs in recent conflict. Data was obtained about military personnel from 2006 to 2011, who had sustained a knee dislocation while serving in Afghanistan from a prospectively gathered database, the Joint Theatre Trauma Registry (JTTR), maintained by the Academic Department of Military Emergency Medicine, Royal Centre for Defence Medicine. The diagnosis of knee dislocation and its associated skeletal injuries was assessed by review of all relevant plain radiographs, computed tomography scans and magnetic resonance images. The mechanism of injury, incidence of vascular injuries and other skeletal injuries was recorded. During the study period, 23 casualties sustained a knee dislocation caused by an IED. Four casualties had an associated popliteal vascular injury. Eleven injuries were caused in enclosed spaces, and 10 injuries caused by IEDs out in the open. Anterior dislocations were common in the group caused in enclosed spaces. 19/20 patients had at least one other skeletal fracture. Knee dislocations represent an uncommon but important diagnosis in modern warfare. Urgent and careful assessment for any associated vascular injuries or other skeletal injuries may help ensure timely treatment and promote future recovery. Mitigation against knee dislocation may be possible in the enclosed environment because of the predictable pattern of injury.
Circumferential pelvic binders have been developed to allow rapid closure of the pelvic ring in unstable fracture patterns. Despite evidence to support the use of pelvic binders, there is a paucity of clinical data regarding the effect of binder position on symphyseal diastasis reduction. All patients presenting to the UK's military hospital in Afghanistan who survived and underwent pelvic radiography were reviewed. Cases were identified by retrospective assessment of all digital plain pelvic radiographs performed between January 2008 and July 2010. All radiographs and CT images were assessed to identify the presence of any pelvic fracture. Patients were grouped into three categories according to the vertical level of the buckle: superior to the trochanters (high), inferior to the trochanters (low) and at the level of the trochanters (troch). Diastasis reduction was measured in patients with Anterior-Posterior Compression (APC) grades II and III, or Combined Mechanical Injuries(CMI). Comparison of diastasis reduction between the high and troch groups was assessed by an independent samples Student's t-test. We identified 172 radiographs where the metallic springs in the buckle of a SAM Pelvic Sling™ were clearly visible. The binders were positioned at the trochanteric level in 50% of radiographs. A high position was the commonest site of inaccurate placement (37%). In the patients with fractures and an open diastasis, the mean pelvic diastasis gap was 2.75 times greater in the high group compared to the trochanteric level (mean difference 22 mm) (p < 0.01). Application of pelvic binders superior to the greater trochanters is commonplace and associated with inadequate fracture reduction, which is likely to delay cardiovascular recovery in these significantly injured casualties.
Introduction. This is the first study to illustrate spinal fracture distribution and the impact of different injury mechanisms on the spinal column during contemporary warfare. Methods Retrospective analysis of Computed Tomography (CT) spinal images entered onto the Centre for Defence Imaging (CDI) database, 2005-2009. Isolated spinous and transverse process fractures were excluded to allow focus on cases with implications for immediate management and prospective disability burden. Fractures were classified by anatomical level and stability with validated systems. Clinical data regarding mechanism of injury and associated non-spinal injuries for each patient was recorded. Statistical analysis was performed by Fisher's Exact test. Results 57 cases (128 fractures) were analysed. Ballistic (79%) and non-ballistic (21%) mechanisms contribute to vertebral fracture and spinal instability at all regions of the spinal column. There is a low incidence of cervical spine fracture, with these injuries predominantly occurring due to gunshot wounding. There is a high incidence of lumbar spine fractures which are significantly more likely to be caused by explosive devices than gunshot wounds (p<0.05). 66% of thoracolumbar spine fractures caused by explosive devices were unstable, the majority being of a burst configuration. Associated non-spinal injuries occurred in 60% of patients. There is a strong relationship between spinal injuries caused by explosive devices and lower limb fractures Conclusion Explosive devices account for significant injury to both combatants and civilians in current conflict. Injuries to the spine by explosions account for greater numbers, associated morbidity and increasing complexity than other means of injury.
Locking internal fixation through a relatively small surgical dissection presents an innovative technique for managing distal tibial extra-articular fractures. The aim of this study is to evaluate the biomechanical properties of one locking internal fixation plate used to treat these injuries. An AO/OTA43-A3 fracture was created in synthetic composite tibiae. Locking internal fixation was achieved with an anatomically pre-contoured medial distal tibial locking plate. Comparisons were made between different screw configurations in holes proximal to the fracture and monocortical versus bicortical fixation. Axial stiffness was measured using a universal materials testing machine. Finite element analysis (FEA) was used to model the elastic deformation of the constructs. Outcome measures were axial stiffness under physiological loading conditions and compression load to failure.Background
Method
This study evaluates the effect of lower limb post-operative mechanical axis on the long term risk of revision surgery following primary total knee arthroplasty (TKA). The study is relevant because many recent clinical trials have evaluated the optimal surgical technique for accurately aligning components in TKA, despite little evidence that alignment may effect the long-term clinical outcome. The data used in this study was collected prospectively as part of a randomized control trial comparing the long term survival of cemented versus uncemented TKA. The trial included 501 press-fit condylar posterior cruciate ligament-retaining prostheses performed by the senior author (PJG) or under his direct supervision. The post-operative mechanical axis alignment of the lower limb was measured following TKA using standard AP weight-bearing long leg alignment radiographs. A comparison was made between a well-aligned group with a mechanical axis alignment within 3° of neutral; and a poorly-aligned group whose mechanical axis alignment deviated greater than 3° from neutral. Survival analysis used revision surgery, with exchange of any of the three originally inserted components (femoral, tibial, polyethylene insert), as the endpoint. There was no loss to follow-up in this study. The minimum follow-up of TKAs in this study was 5.8 years. In the population of TKAs that were followed up at 10 years, 6% (17/270) required revision surgery. There was a significant difference in the rate of revision surgery between the well-aligned group 5% (11/227) and the poorly-aligned group 14% (6/43 p<
0.05) This study shows that post-operative lower limb mechanical axis alignment is an important determinant of the need for revision surgery at 10 years. Surgeons performing TKA should pay particular attention to the placement of the tibial and femoral components, so that a mechanical axis within 3° of neutral is achieved.
The role of Evidence Based Medicine in modern surgical practice is to provide a framework for the integration of expertise, evidence and the biology of the individual patient. The research presented at the Combined Services Orthopaedic Society (CSOS) annual meeting is an important source of evidence which is used to support clinical decisions made about patients on military operations and in the NHS. The purpose of this study is to review the levels of evidence presented at this meeting since 2001. We reviewed all of the abstracts presented at the annual meetings of the CSOS between 2001 and 2008, and a single meeting of both the Society of Military Orthopaedic Surgeons (SOMOS) and the British Trauma Society (BTS). Basic science studies, animal studies, cadaveric studies, surveys and guest lectures were excluded. The research abstracts were coded by the lead author (TJB), according to the Oxford Centre for Evidence-based Medicine Levels of Evidence. A second author (AM) reviewed the coding of all abstracts to provide inter-observer reliability. Statistical analysis included a chi-squared test to compare the percentages of each level of evidence between the meetings and between each year of the CSOS meeting. We identified 140, 51 and 96 abstracts in the CSOS, SOMOS and BTS group respectively, which met the inclusion criteria. Level 1 evidence accounted for 73.8%, 64.7% and 68.8% in the CSOS, SOMOS and BTS groups respectively. Level 1 evidence was uncommon at all three meetings representing 4.1%, 5.9% and 8.3% in the CSOS, SOMOS and BTS groups respectively. The chi-squared test did not demonstrate any statistical difference in the evidence levels between the three groups (X2=11.63 (8df), p=0.17). There was no significant difference in the levels of evidence between years during the study period at the CSOS meeting. The average level of evidence presented at the CSOS annual meeting compares favourably with other trauma meetings. The high proportion of level 4 evidence presented at these meetings reflects the challenging task of performing research in trauma surgery. This challenge is further exacerbated in the military environment where operational commitments must be the priority. However, simple methods to strengthen research may involve the inclusion of control groups, prospective patient enrolment, standard treatment protocols, well-defined outcome measures, logistical support for good follow-up and use of patient-focused assessment tools. Co-ordination and focus of military orthopaedic research effort may advance the quality of research produced.
We present a retrospective comparative review of the radiological outcomes of Chevron and Scarf with Akin osteotomy in the treatment of hallux valgus.
The mean post-operative intermetatarsal angles (IMA) were: Chevron mean 8.050, standard deviation 2.560, standard error 0.57. Scarf with Akin mean 7.220, standard deviation 2.56, standard error 0.57. The difference in postoperative IMA between the two groups did not achieve statistical significance. The mean change in IMA for each was: Chevron mean increment 4.90 Standard deviation 2.290, standard error 0.51. Scarf with Akin mean increment 6.680, standard deviation 4.130, and standard error 0.88. The difference in alteration of IMA between the two groups did not achieve statistical significance.
These radiological outcomes were compared with alignment outcomes for ‘Star’ total ankle replacement, as published by PLR Wood. (Total Ankle Replacement JBJS April 2003 85B, pg 334)
32/35 Angle A were within the published accepted range (850–950). 23/35 Angle B were within the published accepted range (800–900). 35/35 Angle C were within the published accepted range (200–400) No statistical difference between the distribution of angle A, B and C and the means for A, B and C for the published results.
A lower angle B positions the implant on metaphyseal bone with a risk of subsidence. Comparing Angle B with a modified acceptable range (850–950) 31/35 fell in the new range.
