Incidence and Profile of Severe Cycling Injuries After Bikeway Infrastructure Changes.

The objective of this study was to evaluate whether bicycling infrastructure changes in the city of Minneapolis effectively reduced the incidence or severity of traumatic bicycling related injuries sustained by patients admitted to our Level 1 Trauma Center. Data for this retrospective cohort study was obtained from the trauma database at our institution and retrospective chart review. The total number of miles of bikeway in the city on a yearly basis was used to demonstrate the change in cycling infrastructure. Adjusted regression analysis demonstrated a significant reduction in ISS when total bike lane miles increased (Coef. - 0.04, P < 0.001). Increasing bike lane miles was also associated with a significant reduction in severe head injury (OR 0.99, P < 0.001) and ICU LOS (Coef. - 0.17, P = 0.013). The miles of bike lanes were not associated with any significant changes in mortality or mechanical ventilation days when adjusted for other factors. We were able to demonstrate a reduction in the severity of injuries incurred by cyclists in the setting of a significant increase in the total number of bicycle lane miles. Our data lends credence to the existing evidence that the addition of bicycle lane miles increases cyclist safety.

Rib reconstruction of the absent mandibular condyle in children.

OBJECTIVES: To describe pediatric costochondral graft reconstruction of the absent mandibular condyle and to report the short-term and long-term outcomes and complications associated with performing this procedure in young children. STUDY DESIGN: Case series with a retrospective chart review. SETTING: Pediatric otolaryngology clinic and tertiary children's hospital in a metropolitan area. SUBJECTS AND METHODS: All children treated for an absent mandibular condyle with a costochondral graft at Children's Hospitals and Clinics of Minnesota were identified from 2002 through 2011, and a retrospective chart review was performed. RESULTS: Ten patients aged 3 to 11 years were identified. The most common diagnosis, in 8 of 10 patients, was oculo-auriculo-vertebral syndrome. Three of the patients had a tracheostomy, of which 1 was decannulated following condylar reconstruction. Functional improvement, defined as improved symmetry, chewing, or better oral opening, was observed in 8 of 10 patients. Five patients have required no further surgeries to date, with a mean follow-up time of 3.9 years. Severe overgrowth of the graft was noted in 1 case, and partial or complete resorption of the graft was also noted in 3 cases. Overgrowth occurred after 5.7 years, whereas resorption occurred after an average of 2.5 years. CONCLUSIONS: Costochondral grafts are an excellent surgical treatment option for children with severe mandibular malformations. Short-term results show particular improvement in function and mandibular alignment. The mean follow-up time with no revision surgery was substantial and indicates that rib grafting is a good addition to the armamentarium of treatment for this patient population.

Quantification of intradiscal pressures below thoracolumbar spinal fusion constructs: is there evidence to support "saving a level"?

STUDY DESIGN: In vitro cadaveric study. OBJECTIVE: The purpose of this study was to quantify the relative biomechanical protection resulting from "saving a level" in long spinal fusions. SUMMARY OF BACKGROUND DATA: "Saving levels" in spinal deformity surgery is desirable. Constructs with lowest instrumented vertebra (LIV) in the lumbar spine may increase loads on unfused lumbar intervertebral discs, leading to accelerated disc degeneration. No study to date has quantified the relative pressure changes that occur in the unfused caudal discs with progressively longer fusions. METHODS: We used a validated in vitro cadaveric long fusion model to assess intradiscal pressures (IDPs) below simulated fusions. Eight fresh frozen T8-S1 specimens were instrumented from T8 to L5. A follower-type loading system and 7.5-N·m moments were applied in flexion and extension. IDP profiles were assessed with a pressure transducer. After acquiring IDP measurements at a given construct length, the rod was cut 1 level higher until LIV = T12. IDP data from each unfused disc were averaged and normalized to the mean value of the disc when immediately subjacent to the LIV. RESULTS: In both flexion and extension, the mean normalized IDP of the unfused discs below the LIV increased with increasing fusion length. For each 1-level increase in construct length, pressure increased by 3.2% ± 4.8% in flexion and 4.3% ± 4.5% in extension for each unfused disc. Although the differences in pressure for a given unfused disc with differing LIV were not significant, there were significant differences between unfused discs at a given LIV. With shorter fusion lengths, pressure in the disc immediately subjacent to the fusion was consistently greater than for the caudal-most discs. CONCLUSION: Unfused caudal lumbar discs experienced increased IDPs with increasing length of instrumentation, most notably at the subjacent discs closest to the LIV.

Mechanical testing of orthopedic suture material used for extra-articular stabilization of canine cruciate ligament-deficient stifles.

OBJECTIVE: To determine (1) if braided, polyblend orthopedic suture materials are mechanically superior to monofilament nylon leader and (2) have mechanical properties similar to biomechanical properties of the canine cruciate ligament. SAMPLE POPULATION: Different suture material types. METHODS: Mechanical testing was performed on 5 different orthopedic suture materials: 80# test Mason monofilament nylon leader (MNL), FiberTape (FT), FiberWire (FW), Xgen OrthoFiber (XOF), and LigaFiba (LF) using a servohydraulic materials-testing machine. Materials were loaded to failure while collecting data for tensile strength, load at 3 mm and 5 mm of elongation and stiffness. Cyclic elongation of each suture material was tested under physiologic loading between 70 and 150 N for 1000 cycles using 3 mm of elongation to describe excessive elongation. Load at 3 mm of elongation and performance during cyclic testing were compared to previously published physiologic loads in the dog stifle. RESULTS: Ultimate tensile strength was greatest with LF, followed by XOF that was stronger than FT and FW, and the weakest was MNL. LF was the stiffest of all tested materials at 3 mm of elongation. Cyclic elongation was greatest for the MNL elongating 3.75 mm after 1000 cycles. All polyblend braided materials continued to elongate throughout the 1000 cycles under physiologic loads. CONCLUSIONS: Polyblend suture materials are stronger and elongate less than MNL in pure tension. The mechanical performance of all sutures tested is questionable when compared with the mechanical demands of the normal stifle in a mid-sized dog.

Improving vastus medialis obliquus function reduces pressure applied to lateral patellofemoral cartilage.

The current study was performed to characterize how improving vastus medialis obliquus (VMO) function influences the pressure applied to patellofemoral cartilage. An additional focus was characterizing how lateral and medial cartilage lesions influence cartilage pressures. Ten knees were flexed to 40 degrees, 60 degrees, and 80 degrees in vitro, and forces were applied to represent the VMO and other muscles of the quadriceps group while a thin film sensor measured joint pressures. The knees were loaded with a normal VMO force, with the VMO force decreased by approximately 50%, and with the VMO unloaded. After tests were performed with the cartilage intact, all tests were repeated with a 12-mm-diameter lesion created within the lateral cartilage, with the lateral lesion repaired with silicone, and with a medial lesion created. Based on a two-way repeated measures ANOVA and post-hoc tests, increasing the force applied by the VMO significantly (p < 0.05) decreased the maximum lateral pressure and significantly increased the maximum medial pressure at each flexion angle. A lateral cartilage lesion significantly increased the maximum lateral pressure, while a medial lesion did not significantly influence the maximum medial pressure. Improving VMO function can reduce the pressure applied to lateral cartilage when lateral lesions are present.