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Nonproductive cross metathesis is described in order to involve a chain-carrying ruthenium methylidene. Dimethyl allylmethylallylmalonate substrate, which has formed a trisubstituted olefin product, is used for delineating the effect of catalyst structure on the relative efficiencies of the processes.

A series of ruthenium olefin metathesis catalysts bearing N-heterocyclic carbene (NHC) ligands with varying degrees of backbone and N-aryl substitution are prepared. Robotic technology is used for examining the activity and stability of each catalyst in metathesis, which has provided insights into the relationship between ligand architecture and enhanced efficiency.

Background: Pilon fractures are high-energy fractures about the ankle observed commonly in both civilian and military trauma populations. Despite surgical management, outcomes are predictably poorly characterized by functional deficits secondary to pain and stiffness. The Intrepid Dynamic Exoskeletal Orthosis (IDEO) and Return-to-Run clinical pathway were initially designed to treat military service members after complex battlefield lower extremity injuries. The IDEO has been used to treat nonbattlefield injuries, but, to our knowledge, it has not been studied specifically among patients with pilon fractures. By studying the use of the IDEO in this patient population, we hope to learn how it might improve ambulation in the community, relieve pain, and return patients to work to better identify patients who might benefit from its use.Questions/purposes: The purpose of this study was to determine whether the IDEO would improve gait parameters including velocity, cadence, stride length, and single-leg stance duration in patients with pilon fractures. Our secondary endpoints of interest were reductions in pain and return to duty.Methods: A prospectively collected database of all active-duty IDEO users at a single institution was queried for all patients using the IDEO after a pilon fracture. Patients were included if they were using the IDEO after sustaining a surgically treated pilon fracture and had exhausted all nonoperative therapies. Exclusions were patients with an incomplete gait analysis at the two study time points. Seven patients meeting these criteria were identified. Three-dimensional gait analysis was performed two times: first wearing shoes at a self-selected speed and second after a custom-made IDEO was fabricated for the patient and completion of the Return-to-Run pathway. Patients reported their average pain while ambulating using a numeric rating scale. Gait variables of interest were velocity, cadence, stride length, and single stance time. Return to military service was assessed through the military medical record. To return to duty, a service-specific physical readiness test must be completed.Results: Median gait velocity improved from 1.1 (interquartile range [IQR], 0.9-1.2) to 1.3 m/s (IQR, 1.2-1.5; p = 0.01). All other variables did not change: cadence 98.4 (IQR, 93.0-107.2) to 104.5 steps/min (IQR, 103.0-109.0; p = 0.13), affected stride length 1.3 (IQR, 1.0-1.4 m) to 1.4 m (IQR, 1.3-1.6 m; p = 0.07), and affected single stance 0.42 (IQR, 0.41-0.47) to 0.43 (IQR, 0.42-0.44; p = 0.80). Pain did not change between time points: 3 (IQR, 2-3) to 2.5 (IQR, 1-3.5; p = 0.90). Three of seven patients returned to duty.Conclusions: At self-selected walking speeds, we observed no improvements in gait parameters or pain after application of the IDEO that would likely be considered clinically important, and so the device is unlikely to be worth the cost in this setting. It is possible that for higher demand users such as elite athletes, the IDEO could have a role after severe lower extremity trauma; however, this must be considered speculative until or unless proven in future studies.Level Of Evidence: Level III, therapeutic study. [ABSTRACT FROM AUTHOR]

Background: Surgical attempts at lower limb preservation after trauma may be complicated by pain and gait disturbances, which can impact the activity level of a military service member. It is unclear how later transtibial amputation (TTA) might affect patients who elect this option after attempts at limb preservation.Questions/purposes: The purposes of the study were to compare preamputation and postamputation (1) the numeric rating scale for pain and pain medication use; (2) self-reported activity level, Four Square Step Test (FSST) results, and assistive device use; and (3) spatiotemporal variables measured with instrumented gait analysis in individuals who elected TTA after multiple attempts at limb preservation.Methods: Retrospective review revealed 10 patients with unilateral lower extremity injuries who underwent late TTA between 2008 and 2016. All patients had undergone multiple limb preservation attempts and had completed instrumented gait evaluations as part of their routine care before and after TTA. One patient was excluded as a result of short followup. The remaining nine patients (eight men, 29 ± 6 years) averaged five surgeries before amputation. Injuries were from improvised explosive devices (six), motorcycle accidents (two), and one training accident. Strict indications for amputation were pain, difficulties performing activities of daily living, limited physical function, and medication dependence. Data for the aforementioned purposes were collected by gait laboratory staff before and 8 to 17 months after amputation. Time to TTA after initial injury was 5 ± 3 years. At the start of the gait analysis study, pain was assessed at rest, activity level was recorded by patient report, and the FSST was administered.Results: After TTA, there was a decrease in pain scores from 4 ± 2 to 1 ± 1 and patients using narcotics decreased from four to only one patient. Self-reported walking endurance increased from 1 ± 1 mile to 7 ± 8 miles and patients able to run increased from one patient to eight with the ninth having no desire to run but bicycled. Patient FSST times improved from 12 ± 10 seconds to 5 ± 1 seconds. No patients required assistive devices after TTA. There were improvements in velocity (108 ± 16 cm/s to 142 ± 7 cm/s), stride length (129 ± 14 cm to 154 ± 8 cm), cadence (101 ± 9 steps/min to 111 ± 7 steps/min), and step width (16 ± 3 cm to 12 ± 2 cm) between pre- and postassessments. Asymmetric single-limb stance time was measured both pre- and postamputation; this did not worsen with the increase in walking velocity.Conclusions: The findings of this study show that TTA after attempted limb preservation in a young, motivated group of service members after traumatic injuries can be successful in decreasing pain and narcotic use and can allow for high-level functional activities. Future studies will be needed to compare this cohort with patients who underwent early TTA after traumatic injury. However, we acknowledge that the resources and support structure available for this population are unique and may not be readily available to the general population.Level Of Evidence: Level IV, therapeutic study. [ABSTRACT FROM AUTHOR]

Background: Through-knee amputation is a common amputation level after battlefield injuries during the medical evacuation process. However, there are limited data comparing through-knee amputation with transfemoral amputation as a definitive amputation level in terms of gait parameters.Questions/purposes: (1) Does through-knee amputation result in improved gait velocity when compared with matched transfemoral amputees? (2) Do through-knee amputees have a faster gait cadence than matched transfemoral amputees? (3) Do through-knee amputees have a different stride length or stride width than matched transfemoral amputees? (4) Does through-knee amputation result in decreased work of ambulation when compared with matched transfemoral amputees?Methods: Between January 2008 and December 2012, six male active-duty military patients who had undergone unilateral through-knee amputations as a result of trauma underwent gait studies at our institution. Of those, four of six underwent gait analysis after being able to walk for at least 3 months without assistive devices, and this group was studied here. Most through-knee amputees who were not included had elective revisions of their amputations from through-knee to a transfemoral amputation before completing 3-month gait data. Each of the amputees studied was matched to a transfemoral amputee based on height, body mass index, and contralateral amputation level resulting in a case-control study of active-duty military male amputee patients. Inclusion required complete gait data collected while walking at a self-selected pace wearing custom prosthetic devices. The through-knee amputees had a median (range) age of 32 years (23-41 years) and the transfemoral amputees had a median age of 24 years (22-27 years). Three-dimensional gait data were collected and analyzed. A power analysis found that to detect a clinically important difference (set at a change in work of ambulation of 1 J/kgm) with a p value of 0.05 and a β set to 0.2, a study population of 56 patients per group would be required; that being said, our results on a much smaller population must be considered exploratory.Results: With the numbers available, we found no differences in gait velocity when comparing through-knee (1.18 m/sec) and matched transfemoral amputees (1.20 m/sec, difference of medians = 0.02 m/sec; p = 0.964). Likewise, we found no differences in gait cadence when comparing through-knee with transfemoral amputees (104 versus 106 steps/min, respectively, difference of means 2 steps/min, p = 0.971). There was no difference in stride length or stride width when comparing through-knee (70 cm and 18 cm, respectively) with transfemoral amputees (70 cm and 19 cm, respectively; p = 0.948 and p = 0.440). With the numbers available, we did not identify a difference in the work of ambulation for through-knee amputees when compared with matched transfemoral amputees (8.3 versus 7.5 J/kg, respectively; p = 0.396).Conclusions: Based on our findings, we are unable to demonstrate any functional advantages of knee disarticulation over transfemoral amputation. Although there are theoretical advantages for maintaining an intact femur during the medical evacuation and serial débridement process, we question the utility of knee disarticulation as a definitive amputation level; however, larger numbers of patients are needed to confirm these results.Level Of Evidence: Level III, therapeutic study. [ABSTRACT FROM AUTHOR]

Retrospectively compare outcomes of prophylactic fixation to nonoperative treatment of incomplete or non-displaced femoral neck stress fractures (FNSF) in young adults. Outcomes of 82 patients (mean age 21.7 years) who were diagnosed with incomplete or non-displaced FNSFs from 2002 to 2015 were compared. Forty-one underwent prophylactic fixation; the remaining were treated without surgery. Fracture characteristics and complications were recorded. Pain scores, modified Harris Hip Scores (mHHS), and Hip Outcome Scores (HOS) were obtained and compared. The average fracture line in the operative group was 67% of the femoral neck width versus 18% in the nonoperative group (p < 0.001). There was no difference in outcome scores between the two groups. Prophylactic fixation of high-risk non-displaced FNSFs resulted in similar outcome scores to non-operative management of lower-risk variants at an average of 7.3 years follow up. No patient in either group progressed to a displaced femoral neck stress fracture. (Journal of Surgical Orthopaedic Advances 29(3):173-176, 2020).

The purpose of this study was to determine whether active duty military members treated surgically for incomplete femoral neck stress fractures (FNSFs) return to duty. A retrospective review of 53 patients was evaluated to determine the rate of return to duty (RTD) related to sex, branch of service, side of fracture, and signs of femoroacetabular impingement (FAI). Signs of FAI were measured and compared to RTD. Sixty-seven percent of the sample population did not return to duty. Eighty-three percent of Marine Corps members did not return to duty and 18% of Navy active duty members did not return to duty. This finding was statistically significant ( p < .001). Average follow-up was 25 months. Surgical fixation of FNSFs does not seem to affect the ability to return to active duty; however, it did prevent progression to complete or displaced fracture in all of the study patients. (Journal of Surgical Orthopaedic Advances 27(4):312-316, 2018).

The purpose of this study was to compare the accuracy of pin placement in patients with unstable pelvic fractures undergoing either iliac crest or supra-acetabular external fixation. A retrospective review was performed of computed tomography (CT) scans and injury characteristics for all patients presenting to a North Atlantic Treaty Organization Medical Treatment Facility with data entered into the Department of Defense Trauma Registry from January 2008 to October 2013 who underwent pelvic external fixation for unstable pelvic ring injuries. Thirty-two patients were analyzed. Sixteen patients underwent damage control iliac crest-based and 16 patients underwent supra-acetabular-based external fixation. There was no significant difference in patient characteristics at presentation between the two groups. Pin malposition rate on CT scan was 50/64 (78.1%) for the iliac crest group and 3/32 (9.4%) for the supra-acetabular group. Pin malposition was correlated with increasing Injury Severity Score, Abbreviated Injury Scale (AIS) head score, and AIS face score. The review concluded that iliac crest-based external fixation has a significantly higher rate of pin malposition than supra-acetabular-based external fixation.

There are no data-supported recommendations on how proximal is too proximal for retrograde nailing (RGN). At six level 1 trauma centers, patients with femur fractures within the proximal one-third of the femur treated with RGN were included. This article describes a proximal segment capture ratio (PSCR) and nail segment capture ratio to evaluate RGN of proximal fractures. The study included 107 patients. The average follow-up was 44 weeks. There were two nonunions and three malunions. There was no significant difference between PSCR of 0.3 or less and need for secondary procedures or time to full weight bearing (p>.05). In this study, a smaller (< 0.3) PSCR was not associated with an increased number of complications. A higher Orthopaedic Trauma Association classification was predictive of malunion and increased time to union. These data demonstrate that retrograde nailing is safe and effective for the treatment of supraisthmal femur fractures.

The purpose of this study is to retrospectively review the results of proximal third femur fractures treated with retrograde nailing (RGN) and compare those results to a cohort from the same period treated with antegrade nailing (AGN). Adult patients with femur fractures within 10 cm of the lesser trochanter who were treated with intramedullary nails were reviewed. Two groups, patients treated with AGN (n = 35) and RGN (n = 34), were compiled. Demographic information, comorbidities, associated injuries, radiographic outcomes, complications, and secondary procedures were compared. There were two malunions in the AGN group and three in the RGN group. The AGN group had two nonunions while the RGN group had one. Subgroup analysis demonstrated that a higher body mass index (BMI) (p = .011) and a higher AO/OTA fracture classification (p = .019) were the only factors predictive of malunion. Regardless of starting point, there were no differences between groups in the number of secondary procedures, nonunions, malunions, or time until union.

Acetabular fracture-dislocations are severe injuries that require urgent closed reduction of the hip and often require surgery to restore hip stability. Other authors have described acetabular fracture-dislocations associated with femoral neck fractures, but to our knowledge, this case report is the first to describe an acetabular fracture-dislocation in association with an ipsilateral pertrochanteric fracture and subtrochanteric extension. The polytraumatized patient initially was not stable enough for prolonged surgery. Through a 3-cm anterolateral hip incision, a 5-mm Schanz screw was introduced percutaneously into the femoral head through the primary fracture site under fluoroscopic guidance. With inline traction on the leg, the Schanz screw was used to manipulate the femoral head back into the acetabular fossa. The Schanz screw was removed, the head remained reduced, and a skeletal traction pin was placed to maintain length and alignment of the pertrochanteric fracture until definitive stabilization was possible. We propose a staged treatment strategy consisting of early closed reduction of the hip, and after the patient has been stabilized, reduction and fixation of the fractures. This strategy may be useful in managing an unstable polytraumatized patient or a patient who requires prolonged transfer to receive definitive care.