Faculty Bibliography

OBJECTIVE: To compare the screw sliding characteristics and biomechanical stability of four-part intertrochanteric hip fractures stabilized with an intramedullary nail using either one large-diameter lag screw (intramedullary hip screw [IMHS]; Smith & Nephew, Memphis, TN) or two small-diameter lag screws (trochanteric antegrade nail [TAN]; Smith & Nephew, Memphis, TN). DESIGN: Laboratory investigation using eight matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric hip fractures. INTERVENTION: One femur of each matched pair was stabilized with an IMHS intramedullary nail, and the other was stabilized with a TAN intramedullary nail. Femurs were statically, then cyclically loaded on a servohydraulic materials testing machine. Finally, all specimens were loaded to failure. MAIN OUTCOME MEASURES: Screw sliding and inferior and lateral head displacements were measured for applied static loads from 500N to 1250N. The same measurements were obtained before and after cyclically loading the specimens at 1250N. Ultimate failure strength of the implant constructs also was determined. RESULTS: There was no significant difference between the TAN and IMHS in static or cyclical loading with respect to screw sliding or inferior and lateral head displacements. There was a statistically significant difference (P < 0.02) in failure strength, with the IMHS construct failing at an average of 2162N and the TAN construct failing at an average of 3238N. CONCLUSION: The two constructs showed equivalent rigidity and stability in all parameters assessed in elastic and cyclical tests. The TAN had a greater ultimate failure load

The accuracy of measuring angulation of stable proximal humerus fractures using the axillary lateral projection was investigated. A closing wedge osteotomy with apex anterior angulation was performed on two cadaveric humeri to simulate a stable surgical neck fracture. One specimen was fixed at 30 degrees angulation and the other at 55 degrees. Axillary radiographs were taken with each specimen articulating with the glenoid of a cadaveric scapula. The humerus was held in neutral rotation. Abduction was set at 30 degrees, 60 degrees, and 90 degrees. In each position of abduction, an axillary lateral radiograph was taken in 30 degrees forward flexion, neutral, and 30 degrees extension to simulate various arm positions. A total of nine radiographs were taken for each specimen. The axillary view is not accurate for measurement of proximal humerus angulation at the arm positions commonly encountered in the trauma setting

BACKGROUND:: Bicondylar tibial plateau fractures are complex injuries, historically associated with high complication rates. The purpose of this study was: 1) to evaluate the clinical use L.I.S.S plating system for stabilization of bicondylar tibial plateau fractures. 2) To compare the biomechanics of this plating system with a double plate construct. METHODS AND MATERIALS:: Thirty-eight patients who sustained a complex tibial plateau fracture (OTA type 41C) at one of three level-one trauma centers were stabilized using the Less Invasive Stabilization System (L.I.S.S.). The cohort of patients was evaluated clinically and radiographically for outcomes at a mean 15 months.In phase 2 of this study a model of a bicondylar tibial plateau fractures was made in six matched pairs of embalmed, human tibia and randomized to fixation with either a L.I.S.S plate or a standard double plate construct. The tibias were then subjected to an axial cyclic load of 500N for 10 cycles (3Hz) to approximate 2 months in vivo and displacements measured. RESULTS:: Thirty-six of /38 (95%) patients united at 4 months after surgery with no loss of fixation nor infection. Two patients underwent prophylactic autogenous bone grafting for bone loss and united by 3 months postgrafting. Significant loss of knee range of motion (<90) was seen in five patients.Biomechanically, no differences in permanent inferior displacement of the medial fragment were found in initial axial loading and after 10 cycles between the two plate constructs. However, when loaded to 500N the L.I.S.S plate construct demonstrated almost twice the displacement of the medial fragment compared with the dual plate construct. No specimen lost fixation during cycling. CONCLUSION:: The L.I.S.S plating system provides stable fixation of complex bicondylar tibial plateau fractures allowing early range of knee motion with favorable clinical results

OBJECTIVES: The anterior curvature of the femur affects intramedullary nail insertion, revision prosthesis design, and the biomechanics of the proximal femur. Two previous studies, using small numbers of femurs, determined femoral curvature and showed that it was significantly greater than that of the several intramedullary nails they evaluated. In this study, the curvature of 948 femurs (474 matched pairs) was determined and compared with current intramedullary nails. The correlation of femoral curvature to age, gender, femoral size, and race was also evaluated. SETTING: Museum skeletal collections and a hospital biomechanics laboratory. METHODS: The curvature of 892 femurs (446) from the skeletal collections of 2 museums was measured by processing the digital images of the femurs with a computer curve-fitting program. Fifty-six additional, embalmed femurs (28 pairs) from our collection were also digitally imaged and then radiographed and their medullary curvatures similarly determined for comparison. Curvatures of 8 current antegrade intramedullary nails and 3 long-stemmed femoral hip prostheses were obtained from manufacturers and confirmed by measurements from their templates after digitization. RESULTS: We found the average femoral anterior radius of curvature was 120 cm (+/- 36 cm). There was no effect of age on femoral curvature nor was there a correlation between femoral width or femoral length to curvature. Black donor femurs had less curvature than white donor femurs (P < 0.001). There was close correlation (r = 0.967) between the femoral curvatures determined from the digital images and the radiographs. Radii of curvature of the intramedullary nails ranged from 186 to 300 cm (eg, straighter than the femurs). CONCLUSIONS: There was a large mismatch between the curvature of some current antegrade intramedullary nails and the average femur. Although this is only 1 factor affecting nail insertion, the mismatch warrants a reappraisal of these intramedullary nail designs. CLINICAL RELEVANCE: Because ease of intramedullary nail insertion and possibility of cortical comminution are determined by a number of factors including insertion point and fracture location, it appears that a decrease in radii of curvature (less straight) of current nail designs is warranted, particularly for those larger diameter nails designed for hip fracture stabilization that have greater rigidity due to design or material

BACKGROUND: The lateral trochanteric support plate (LSP) was developed to prevent excessive sliding of unstable intertrochanteric femur fractures fixed with a sliding hip screw (SHS). This study compared the fracture stability and screw sliding characteristics of unstable intertrochanteric femur fractures fixed with either an SHS and LSP or an Intramedullary Hip Screw (IMHS). METHODS: Six matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric femur fractures were stabilized with either an IMHS or a 135-degree SHS with an attached LSP. Inferior and lateral head displacements and lag screw sliding distances were measured for applied static loads of 750 N, before and after cycling. RESULTS: Four-part unstable intertrochanteric femur fractures showed comparable screw sliding characteristics and stability whether instrumented with an SHS and LSP or an IMHS. CONCLUSION: A sliding hip screw with an attached lateral support plate provides stability and ability to resist medial displacement of the femoral shaft similar to that seen with the IMHS

SUMMARY: We present the previously unreported complication of symptomatic heterotopic ossification of the quadriceps following placement of a large-diameter Steinmann pin for the purpose of temporary skeletal traction. Following the development of distal quadriceps heterotopic bone formation in three patients, we conducted a comprehensive search of the literature using the Medline database from 1966 to the present. A variety of publications, including review articles, case reports, and randomized prospective studies, were used for the literature review. This potential complication should be considered when using a large-diameter Steinmann pin in the distal femur for skeletal traction

Instrument wear and tear, mishandling, and abuse can lead to instrument damage, particularly closely machined mating surfaces, which then prevents them from functioning properly. Simple refinishing of these damaged surfaces often resolves these problems. The electrocautery scratch pad can be an excellent means of rapidly refinishing damaged instruments

BACKGROUND: The purpose of this study was to assess the effectiveness of external fixation and percutaneous pinning in maintaining distal radius fracture reduction over a 6-month period and to identify factors that might predict loss of fracture reduction. METHODS: Seventy cases had complete radiographic evaluation before surgery; at surgery; and at 6-week, 3-month, and 6-month follow-up. Radiographic parameters measured included volar tilt, dorsal displacement, radial inclination, radial height, radial shift, and ulnar variance. RESULTS: Dorsal tilt averaged 17.5 degrees from neutral before surgery; this value was corrected to 0.9 degree at surgery, but then progressed to 4.2 degrees by the 6-month follow-up. At 6-month follow-up, 49% of cases had lost more than 5 degrees of initially reduced volar tilt. However, none of these patients went from an acceptable initial reduction to an unacceptable reduction at 6 months. Initial deformity, patient age, use of bone graft, and duration of external fixation were not predictors of loss of reduction. CONCLUSION: Loss of reduction of volar tilt was seen for a period of up to 6 months after fixation, despite the use of pinning to hold the reduction. No specific predictor of loss of reduction was noted, although there was a trend toward loss of reduction in younger patients

Computer assisted fluoroscopic surgery is at the forefront of the ability to continue and pursue minimally invasive surgical options in orthopaedic surgery. Many systems afford the surgeon three-dimensional views and biplanar imaging for placement of orthopaedic implants in difficult areas. The current literature regarding these techniques is limited. The indications are poorly defined. The common thread of all techniques, however, is the preservation of the soft tissue attachments and the biology of the fracture hematoma. Currently we are using first generation implants. It appears that malalignment is the biggest problem with any of these techniques and long-term prospective studies will be required to evaluate whether or not these theoretical advantages become clinically viable and functional for patient care

The purpose of this study was to determine the effect of the last hemoglobin level before patient discharge on outcome after hip fracture. We retrospectively reviewed data prospectively collected from July 1987 to December 1997 on 844 community-dwelling patients 65 or older who had sustained an operatively treated femoral neck or intertrochanteric fracture. Women with postoperative hemoglobin levels below 12.0 g/dL and men with levels below 13.0 g/dL were classified as having anemia. The main outcome measures were mortality, return to ambulatory ability, and return to activities of daily living at 3, 6, and 12 months. Hemoglobin data were available for 714 patients (85%). At time of last hemoglobin level measurement before discharge, 643 (90.1%) of the 714 patients were classified as having anemia. Patients who had sustained a femoral neck fracture that was treated with internal fixation were less likely to have anemia than were patients who had sustained a femoral neck fracture that was treated with hemiarthroplasty and patients who had sustained an intertrochanteric fracture (P < .001). Patients with anemia at the last discharge were not at increased risk for adverse outcomes at 3, 6, or 12 months compared with patients who did not have anemia