Faculty Bibliography

Hip fractures have been among the most studied injury patterns in adults. The number of hip fractures is increasing exponentially, and their treatment costs place great economic strain on society. Recently developed hip fracture treatments, emphasizing cost containment, deformity prevention, and evidence-based medicine, are attempts to optimize patient outcomes. In this article, we outline some of these developments with respect to femoral neck and intertrochanteric fractures

Geriatric fracture patients deserve special considerations in the perioperative period. The goal of geriatric fracture management is restoring mobility and limiting a prolonged recumbency period. A comprehensive multidisciplinary approach involving surgical, medical, rehabilitation, and social work specialists is advocated. Indications, surgical timing, and optimization of comorbid conditions are important issues to be addressed. In addition, anesthesia and postoperative pain control require individual attention in this population. Serving as the background to all these issues are the varied social needs of the elderly who could have a limited support network. This review focuses on the current recommendations for perioperative management of the geriatric patient with a hip fracture

Hip fractures are common injuries in the elderly and are associated with considerable morbidity and mortality. Although technical advances in the treatment of the elderly have resulted in improved fracture fixation and surgical outcomes, clinical pathways have been developed to further improve patient outcome while shortening hospital length of stay after hip fracture. We describe the clinical pathway used since 1990 at the Hospital for Joint Diseases. The outcomes of 747 patients treated before 1990 were compared with outcomes of 318 patients treated at our hospital after initiation of the clinical pathway. Use of the clinical pathway was associated with significant decreases in the acute care hospital length of stay, in-hospital mortality, and 1-year mortality

OBJECTIVE: To review the biomechanical principles that guide fracture fixation with plates and screws; specifically to compare and contrast the function and roles of conventional unlocked plates to locked plates in fracture fixation. We review basic plate and screw function, discuss the design rationale for the new implants, and examine the biomechanical evidence that supports the use of such implants. DATA SOURCES: Systematic review of the per reviewed English language orthopaedic literature listed on PubMed (National Library of Medicine online service). STUDY SELECTION: Papers selected for this review were drawn from peer review orthopaedic journals. All selected papers specifically discussed plate and screw biomechanics with regard to fracture fixation. PubMed search terms were: plates and screws, biomechanics, locked plates, PC-Fix, LISS, LCP, MIPO, and fracture fixation. DATA SYNTHESIS: The following topics are discussed: plate and screw function-neutralization plates and buttress plates, bridge plates; fracture stability-specifically how this effects gap strain and fracture union, conventional plate biomechanics, and locking plate biomechanics. CONCLUSIONS: Locked plates and conventional plates rely on completely different mechanical principles to provide fracture fixation and in so doing they provide different biological environments for healing. Locked plates may increasingly be indicated for indirect fracture reduction, diaphyseal/metaphyseal fractures in osteoporotic bone, bridging severely comminuted fractures, and the plating of fractures where anatomical constraints prevent plating on the tension side of the bone. Conventional plates may continue to be the fixation method of choice for periarticular fractures which demand perfect anatomical reduction and to certain types of nonunions which require increased stability for union

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