Fixation of intertrochanteric hip fractures with sliding devices.
Explore the source record for details and available documents.
Biomechanical Phenomena↗
Biomedical subjects
R F Kyle
Publications and source records attributed to R F Kyle.
Biomechanical analysis of the sliding characteristics of compression hip screws.
UNLABELLED: We examined the effect of screw-plate angle on the sliding characteristics and jamming potential of four popularly used stainless-steel and cobalt-chromium-molybdenum compression hip screws. The actual coefficient of sliding friction for these alloys was measured in each device. The force on the screw required to overcome the static frictional force also was determined, by varying the lengths of screw engaged in the barrel under conditions of static equilibrium representing 130-degree and 150-degree screw-plate angles. For the 130-degree loading configuration, this force was significantly (p < 0.001) higher than that required for the 150-degree loading configuration for all four screw types. The actual coefficient of friction was relatively constant for each material, although slight variations due to differences in design between screw types were found. A positive correlation (p < 0.01) was seen between the apparent coefficient of friction (the ratio of sliding force to normal force) and the length of the screw extending from the barrel. All stainless-steel screws jammed in the 130-degree tests when not completely engaged in the barrel. None of the 150-degree tests produced jamming and none of the cobalt-chromium-molybdenum screws jammed in either the 130-degree or the 150-degree test. Examination of jammed devices by scanning electron microscopy showed galling on the superior surface of both the screw and the barrel. CLINICAL RELEVANCE: Understanding the conditions that facilitate sliding of hip screws aids in ensuring their proper use. The higher the nail-plate angle, the easier it is to impact the hip-fixation device and thus allow bone impaction and stability at the fracture site. The potential for jamming a sliding hip screw is decreased by maximum engagement of the screw in the barrel. Differences in the material and design of sliding hip-fixation devices have relatively little effect on the sliding characteristics compared with the nail-plate angle and the engagement of the screw in the barrel.
Alloys↗
Analysis of six hundred and twenty-two intertrochanteric hip fractures.
Of 622 intertrochanteric fractures, 57% were stable (Types I and II). Twenty-eight per cent were Type III, and 15% were Type IV (the unstable types). The 150-degree telescoping Massie nail proved superior to the fixed 135-degree Jewett nail (particularly for unstable fractures) because it allowed a controlled impaction of the fracture fragments to a stable position. In about one-third of the fractures, some medial displacement occurred. With anatomical reduction and the use of the Massie or ASIF nails, we achieved a decrease in the morbidity and mortality and 96% satisfactory results. Our prospective study was compared with a retrospective study in which other devices were used. Early ambulation and weight-bearing also was a major contributing factor to the improved results in the prospective study. Intertrochanteric hip fractures that are unstable can be fixed with a collapsible nail, and that treatment appears to give as good or better results than the displacement method of Dimon and Hughston or Sarmiento.
Aged↗
Necrotizing fasciitis--a lethal infection.
Explore the source record for details and available documents.
Adult↗
A prospective, randomized study of intramedullary nails inserted with and without reaming for the treatment of open and closed fractures of the tibial shaft.
OBJECTIVES: To determine if there are differences in healing, complications, or number of procedures required to obtain union among open and closed tibia fractures treated with intramedullary (IM) nails inserted with and without reaming. DESIGN: Prospective, surgeon-randomized comparative study. SETTING: Level One trauma center. PATIENTS: Ninety-four consecutive patients with unstable closed and open (excluding Gustilo Grade IIIB and IIIC) fractures of the tibial shaft treated with IM nail insertion between November 1, 1994, and June 30, 1997. INTERVENTION: Interlocked IM nail insertion with and without medullary canal reaming. MAIN OUTCOME MEASURES: Time to union, type and incidence of complications, and number of secondary procedures performed to obtain union. RESULTS: For open fractures, there were no significant differences in the time to union or number of additional procedures performed to obtain union in patients with reamed nail insertion compared with those without reamed insertion. A higher percentage of closed fractures were healed at four months after reamed nail insertion compared with unreamed insertion (p = 0.040), but there was not a difference at six and twelve months. More secondary procedures were needed to obtain union after unreamed nail insertion for the treatment of closed tibia fractures, but the difference was not statistically significant given the limited power of our study (p = 0.155). Broken screws were seen only in patients treated with smaller-diameter nails inserted without reaming, and the majority occurred in patients who were noncompliant with weight-bearing restrictions. There were no differences in rates of infection or compartment syndrome. CONCLUSION: Our findings support the use of reamed insertion of IM nails for the treatment of closed tibia fractures, which led to earlier time to union without increased complications. In addition, canal reaming did not increase the risk of complications in open tibia fractures.
Adolescent↗
Screw position affects dynamic compression plate strain in an in vitro fracture model.
OBJECTIVE: This investigation considers the effect of a variety of screw positions on plate strain in three fracture models. DESIGN: Dynamic compression plate fixation of in vitro fracture models. METHODS: To model a fracture, a plastic pipe was cut transversely and a twenty-hole dynamic compression plate was attached by screws. Eighteen stacked, rectangular, rosette strain gauges were installed on the plate to evaluate strain. Three models were evaluated: two constructs in which there was no contact between the cut ends of the pipe under the fixation plate (small-and large-gap models) and a construct in which there was direct apposition of the cut ends (no-gap model). The pattern and magnitude of strains were assessed as a function of varying combinations of screw position for each model. RESULTS: Maximal plate strain in the gap models was lowest with screws placed closest to the gap, compared with screws placed away from the gap or spaced apart. The no-gap model showed significantly lower strains when screws were placed further from the osteotomy site than when screws were positioned close together or spaced apart. In all cases, maximal plate strain occurred adjacent to the most central screw holes and rapidly dissipated along the length of the plate. CONCLUSION: In a model simulating a comminuted fracture (gap), this study found that screws should be placed as close to the fracture site as possible to minimize plate strain. In an anatomically reduced two-part fracture model (no gap), widely spaced screws or those placed away from the fracture resulted in lower strains.
Bone Screws↗
The effects of freeze-drying and ethylene oxide sterilization on the mechanical properties of human patellar tendon.
Human patellar tendon allografts are used to replace injured anterior cruciate ligaments. They are often stored by freeze-drying or freezing before use and have been sterilized by gamma irradiation or ethylene oxide gas. Studies comparing the mechanical properties of tendons preserved by freeze-drying and sterilized by ethylene oxide have yielded conflicting results. This study examined the effects of freeze-drying and ethylene oxide sterilization on the mechanical properties of human patellar tendons obtained from 11 human cadavers; all were free of musculoskeletal disease. The 22 patellar tendons were halved longitudinally; 7 were frozen at -70 degrees C for 8 weeks and served as controls; 8 were freeze-dried; and 7 were freeze-dried and sterilized with ethylene oxide gas. Ultimate tensile stress and longitudinal strain were greater for frozen than for freeze-dried, but not greater than freeze-dried, ethylene oxide-sterilized tendons (P < 0.05). The modulus of elasticity was similar in all tendon groups. The study suggests that some in vitro mechanical properties of frozen tendons may be marginally superior to the properties of freeze-dried tendons, even after correction for size difference. Ethylene oxide gas sterilization had no adverse effect on tendon mechanical properties.
Aged↗