Biomechanical evaluation of proximally placed femoral less-invasive stabilization system plates.

Loss of fixation of the Synthes 13-hole femoral Less-Invasive Stabilization System (LISS) plate has been noted. The biomechanical stability of this plate may be affected by improper proximal placement. We conducted a study to determine if there is any difference in fixation failure, deformation, or stiffness based on proximal placement. Using synthetic composite bones, we created a comminuted supracondylar distal femur fracture, AO/OTA (Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association) 33-A3. Three groups of 9 femurs each were created: 1 correctly positioned group and 2 incorrectly positioned groups, 1 with the proximal aspect of the plate 1 cm anterior and 1 with the proximal aspect of the plate 1 cm posterior. The constructs were tested in axial, torsional, and cyclical axial modes to assess plastic and total deformation and stiffness. Under axial loading, the posteriorly placed plate showed a 16.4% increase in stiffness. There was a significant increase of 12% in torsional stiffness in the anteriorly placed plate. Under cyclical axial loading, there was a significant increase of 14% in total deformation in the anteriorly placed plate. No fixation failure was observed. One-centimeter variation in proximal placement of a 13-hole LISS plate in a synthetic composite fracture model had little effect on the overall construct.

Economic impact of syndesmosis hardware removal.

Ankle syndesmosis injuries are commonly seen with 5-10% of sprains and 10% of ankle fractures involving injury to the ankle syndesmosis. Anatomic reduction has been shown to be the most important predictor of clinical outcomes. Optimal surgical management has been a subject of debate in the literature. The method of fixation, number of screws, screw size, and number of cortices are all controversial. Postoperative hardware removal has also been widely debated in the literature. Some surgeons advocate for elective hardware removal prior to resuming full weightbearing. Returning to the operating room for elective hardware removal results in increased cost to the patient, potential for infection or complication(s), and missed work days for the patient. Suture button devices and bioabsorbable screw fixation present other options, but cortical screw fixation remains the gold standard. This retrospective review was designed to evaluate the economic impact of a second operative procedure for elective removal of 3.5mm cortical syndesmosis screws. Two hundred and two patients with ICD-9 code for "open treatment of distal tibiofibular joint (syndesmosis) disruption" were identified. The medical records were reviewed for those who underwent elective syndesmosis hardware removal. The primary outcome measurements included total hospital billing charges and total hospital billing collection. Secondary outcome measurements included average individual patient operative costs and average operating room time. Fifty-six patients were included in the study. Our institution billed a total of $188,271 (USD) and collected $106,284 (55%). The average individual patient operating room cost was $3579. The average operating room time was 67.9 min. To the best of our knowledge, no study has previously provided cost associated with syndesmosis hardware removal. Our study shows elective syndesmosis hardware removal places substantial economic burden on both the patient and the healthcare system.

Early experience with the proximal femoral locking plate.

The purpose of this study was to evaluate the failure rate of proximal femoral locking plates after an initial 2 years of use at a Level I trauma center. This retrospective chart review included 13 patients with intertrochanteric or peritrochanteric femoral fractures who underwent open reduction and internal fixation. Average patient age was 47 years (range, 23-80 years); average follow-up was 12.7 months (range, 2 weeks to 23 months). Three (23%) patients experienced catastrophic failure of the implant. The overall revision rate was 46% (6 of 13). One patient experienced avascular necrosis and required a planned total hip arthroplasty. In the appropriate setting, the proximal femoral locking plate can offer stable fixation for fractures involving the proximal femur; however, this series highlights the difficulties associated with treating these injuries, especially in patients with multiple injuries. Care must be taken to avoid varus malalignment and to address metabolic bone dysfunction.

Additive effects of exogenous IL-12 supplementation and antibiotic treatment in infection prophylaxis.

The increasing clinical incidence and host risk of open fracture-associated infections, as well as the reduced effectiveness of conventional antibiotics to treat such infections, have driven the development of new therapies for the prophylaxis of open fracture-associated infections. We investigated percutaneous supplementation of a natural cytokine (i.e., interleukin 12p70 or IL-12) at an open fracture site to reduce open fracture-associated infections. We also determined the efficacy of the combination therapy of IL-12 and conventional antibiotic therapy in the prophylaxis of open fracture-associated infections. An open femur fracture infection model was produced by direct inoculation of a clinical isolate of Staphylococcus aureus after creating a femur fracture using rats. The animals were assigned to one of four groups: no drug administration, percutaneous supplementation of IL-12, intraperitoneal administration of the antibiotic ampicillin, or percutaneous IL-12 in combination with intraperitoneal ampicillin. Animals were euthanized at postoperative days 6, 10, 14, and 21. Percutaneous IL-12 led to a reduction in infection at postoperative days 6 and 10. For the first time, exogenous IL-12 was found to have additive effects in the prevention of infection when combined with conventional treatment (i.e., antibiotic therapy). Combination therapy of ampicillin and IL-12 substantially reduced the infection rate at postoperative day 6 and also decreased the time needed for complete inhibition of infection. Therefore, exogenous IL-12, providing a mechanism of protection independent of antibiotic resistance, complements the routine use of antibiotics.

An animal model for open femur fracture and osteomyelitis--Part II: Immunomodulation with systemic IL-12.

Infection resulting from open fracture is a common problem in orthopedics. The purpose of this project was to study the effect of Interleukin-12 (IL-12) systemic therapy on a previously established open fracture model. One hundred seven male Sprague-Dawley rats were assigned to five groups: (1) normal (baseline), (2) control (controlled for anesthesia), (3) fracture, (4) staph, and (5) staph and IL-12 (SIL). Each group was divided into four time periods: 6, 10, 14, and 21 days after injury and fixation. The operative groups had a standardized femur fracture and fixation using a Kirschner wire as an intramedullary device. The two infection groups (staph and SIL) were inoculated with Staphylococcus aureus following fracture and fixed with an identical technique. The SIL group was treated with systemic IL-12 for a total of 10 doses over 10 days. Significantly decreased serum IL-12 levels were noted at day 10 in the operative groups compared to the normal and control groups. The SIL group showed significantly higher macrophage activation levels and total platelet counts at day 21 compared to all the other groups. The overall infection rate was not changed by IL-12 supplementation; however, bacterial qualitative growth scores were significantly lower in the SIL group at day 10, which corresponded to the lowest level of systemic IL-12 in the fracture group.

An animal model for open femur fracture and osteomyelitis: Part I.

Infection is an everyday problem in orthopaedics and is quite common in open fracture management. To study this process and provide a basis to prevent infection, we developed a model that includes trauma (blunt fracture in the fashion of Bonnarens and Einhorn), surgical stabilization (standardized intramedullary K-wire fixation), and infection (Staphylococcus aureus inoculum). In this two-part study, we found that 10(2) colony-forming units of inoculum produced an optimal infection rate of 90-100%, which substantially challenged the immune system without overwhelming sepsis. We hypothesized that, in traumatic fractures, there is a specific immunological response that may lead to an increased rate of infection. In Part 2, we demonstrated immunosuppression (decreased Interleukin-12 levels) at days 6, 10, and 12 after fracture fixation versus nonfractured control groups (p < 0.05). This study describes a rat model of femur factures with osteomyelitis that allows investigation of posttraumatic immunosuppression.

Lateral tibial plateau fracture depression as a predictor of lateral meniscus pathology.

The goal of this study was to determine if the degree of lateral tibial plateau fracture depression on computed tomography (CT) images predicted the presence of lateral meniscus tears. The study group comprised 85 patients who sustained a lateral tibial plateau fracture and underwent open reduction and internal fixation by the same surgeon. Degree of plateau depression was measured in millimeters by CT. Operative reports were retrospectively reviewed to determine if the lateral meniscus tear was intact or torn at the time of surgery. Twenty-eight patients had a lateral meniscus tear noted at the time of surgery. No significant differences existed in gender, mechanism or energy level of injury, Schatzker classification, or type of fracture among patients with a lateral meniscal tear as compared to those without a tear. Patients with > or =10 mm of plateau depression had an eight-fold increase in risk of having a lateral meniscus tear compared to those with <10 mm of depression. Patients younger than 48 years had a four-fold increase in risk of having a lateral meniscus tear than older patients.This study demonstrated an association between the amount of tibial plateau depression and the likelihood of a lateral meniscus tear. These findings may be used to predict those who have sustained a tear of the lateral meniscus and to advise the surgeon to prepare for a repair. Further prospective studies using magnetic resonance imaging as a tool to evaluate the extent of soft tissue injuries in plateau fractures is needed.