Atypical femoral fractures in elderly women: a fracture registry-based cohort study.

An atypical femoral fracture (AFF), with a transverse fracture radiologically through the lateral cortex is a rare but serious condition. In order to improve our ability to identify patients with this condition, we retrospectively surveyed all subtrochanteric, peri-implant and diaphyseal femoral fractures in patients aged ≥ 65 years who underwent surgical treatment at our hospital between 2004 and 2011. We describe the incidence of atypical fractures and their characteristics, with observational data including a review of the hospital and general practitioner records. Clinical outcomes were evaluated using the Harris hip score (HHS) and the timed up-and-go (TUG) test. Atypical fractures only occurred in women with an incidence of 9.8 per 100,000 person-years. The incidence in those who were treated with bisphosphonates was 79.0 per 100,000 person-years; eight of 17 fractures occurred around metal implants. There was a high incidence of delayed union and revision surgery. A total of nine patients (ten AFFs) were available for review at a mean follow-up of 36.5 months (10 to 104). The clinical outcome was poor with a mean HHS of 58.9 (95% CI 47.4 to 70.4) and a mean TUG test of 25.7 s (95% CI 12.7 to 38.8). The delay in diagnosis and treatment of AFF may result from a lack of knowledge of this condition.

A cyclic testing comparison of FasT-Fix and RapidLoc devices in human cadaveric meniscus.

INTRODUCTION: Cyclic testing may provide a more valid depiction of how arthroscopic meniscal repairs will withstand the forces of activities of daily living (ADLs) and therapeutic exercises early post-surgery than single cycle load to failure testing. This study compared the meniscal fixation provided by vertically or horizontally placed FasT-Fix devices to horizontally placed RapidLoc devices under submaximal cyclic test conditions. MATERIALS AND METHODS: Eighteen human cadaveric menisci were divided into three groups of six specimens. A scalpel was used to create a 2 cm lesion at 3 mm from the outer edge of the posterior third of each specimen. Merselene tape loops were placed around each side of the lesion and the tears were repaired using two vertical FasT-Fix, two horizontal FasT-Fix, or two RapidLoc devices. Cyclic testing (5-50 N at 1 Hz for 500 cycles) was performed on a servo hydraulic device. One-way ANOVA and Scheffe post-hoc tests were used to evaluate group differences (P < 0.05). RESULTS: The vertical FasT-Fix group had less displacement over the initial ten loading cycles compared to the RapidLoc group (P = 0.004), but did not differ from the horizontal FasT-Fix group (P = 0.07). At 50, 100, 200, 300, 400, and 500 cycles, the vertical FasT-Fix group had less displacement than the horizontal FasT-Fix or RapidLoc groups (P < or = 0.004). At each interval the vertical FasT-Fix group had greater relative stiffness than the other groups (P < or = 0.009). CONCLUSIONS: The vertical FasT-Fix group had comparatively less displacement (primarily repair site gapping) and greater relative stiffness.

Biomechanical comparison between CentraLoc and Intrafix fixation of quadrupled semitendinosus-gracilis allografts in cadaveric tibiae with low bone mineral density.

Supplementary or back-up tibial tunnel fixation of a quadruple semitendinosus-gracilis (STG) graft is often performed when the knee surgeon questions the integrity of intra-tunnel fixation. Back-up fixation devices such as staples however may contribute to increased knee pain and dysfunction. Both primary extra-tunnel and intra-tunnel fixation devices may provide sufficient quadruple STG graft fixation in a tibial tunnel to preclude the need for back-up fixation. This biomechanical study compared the fixation of quadruple STG allografts in standard drilled tunnels prepared in low apparent bone mineral density (BMD) cadaveric tibiae using either an Intrafix device with primary intra-tunnel fixation in a region of predominantly cancellous trabecular bone, or a CentraLoc device with primary extra-tunnel fixation in a region of predominantly cortical bone. The study hypothesis was that the CentraLoc device would display superior fixation in these low apparent BMD cadaveric tibiae. Matched pair tibiae and quadruple STG allografts were divided into two groups of seven specimens each. Extraction drilled tunnels matched allograft diameter. Constructs were pretensioned on a servo hydraulic device between 10 and 50 N for 10 cycles and isometric pretensioned at 50 N for 1 min prior to undergoing 500 loading cycles (50-250 N) and load to failure testing (20 mm/min). The CentraLoc group displayed superior load at failure (448.4+/-171 N vs. 338.4+/-119 N, P=0.04) and survived more loading cycles (410+/-154 cycles vs. 196+/-230 cycles, P=0.04) than the Intrafix group. Most CentraLoc group specimens (6/7, 85.7%) failed by device pullout with intact quadruple STG allograft strands while all Intrafix group specimens (7/7, 100%) failed by slippage of one or more strands (P=0.005).

Mechanical properties of compacted morselized cancellous bone graft using one-dimensional consolidation testing.

Failures of orthopaedic procedures that use morselized cancellous bone (MCB) graft for load bearing are often due to gross displacement within the graft material. For this reason the mechanical behavior of MCB must be better understood. Our purpose is to present a detailed testing methodology for the mechanical characterization of MCB, and to illustrate how this methodology can be used to study the influence of water and fat content. Complete one-dimensional consolidation testing was performed on bovine cancellous bone processed to represent MCB typically used in surgery (52% water, 31% fat). The one-dimensional consolidation strain under a stress of 1.09MPa was 30.9% and the confined modulus was 8.0MPa. The coefficient of consolidation (rate of consolidation) was 2. 2x10(-5)cm(2)/s and the coefficient of secondary strain (steady-state creep rate) was 1.9%. While reducing the water content alone had some influence on properties, reducing the fat content improved both the static and dynamic behavior. A sample of MCB which had fat intentionally minimized and a lower overall moisture content (56% water, 5% fat) demonstrated 23.1% strain, a confined modulus of 9.6MPa, a coefficient of consolidation of 3.4x10(-3)cm(2)/s, and a coefficient of secondary strain of 0.9%. The test methods described in this technical note can be used to evaluate the influence of fluid content on the mechanical behavior of MCB.

Bone grafting from the proximal tibia.

OBJECTIVE: A retrospective study was undertaken to analyze the results of proximal tibial bone grafts with immediate postoperative weight bearing. METHODS: Over a 2-year period, 54 patients underwent bone grafting harvested from the proximal tibia. Postoperatively patients were allowed to bear weight as tolerated on the donor site. Mean follow-up was 26.4 weeks, with a range of 6 to 80 weeks. Indications for bone grafting were fresh fractures with primary grafting and nonunions. RESULTS: The overall complication rate was 1.9%, with one patient suffering a local hematoma. No major complications such as fracture, sensory deficit, or wound infection were observed. Immediate postoperative weight bearing did not have any deleterious effects. Higher complication rates for iliac graft sites have been reported. The amount of bone that can be harvested is usually more than adequate. CONCLUSION: Complication rates are low without significant patient morbidity. Most importantly, the patients may start weight bearing immediately after surgery.

Tremulous jaw movements in rats: a model of parkinsonian tremor.

Several pharmacological and neurochemical conditions in rats induce 'vacuous' or 'tremulous' jaw movements. Although the clinical significance of these movements has been a subject of some debate, considerable evidence indicates that the non-directed, chewing-like movements induced by cholinomimetics, dopamine antagonists and dopamine depletions have many of the characteristics of parkinsonian tremor. These movements occur within the 3-7 Hz peak frequency range that is characteristic of parkinsonian tremor. Tremulous jaw movements are induced by many of the conditions that are associated with parkinsonism, and suppressed by several different antiparkinsonian drugs, including scopolamine, benztropine, L-DOPA, apomorphine, bromocriptine, amantadine and clozapine. Striatal cholinergic and dopaminergic mechanisms are involved in the generation of tremulous jaw movements, and substantia nigra pars reticulata appears to be a major basal ganglia output region through which the jaw movements are regulated. Future research on the neurochemical and anatomical characteristics of tremulous jaw movements could yield important insights into the brain mechanisms that generate tremulous movements.

In vivo study of stainless steel and Ti-13Nb-13Zr bone plates in a sheep model.

A sheep study was performed to compare the in vivo performance of bone plates of 316L stainless steel and a new titanium alloy, titanium + 13% niobium + 13% zirconium (Ti-13Nb-13Zr), which had been subjected to a diffusion hardening treatment to produce a blue, wear resistant surface. Bone plates and screws of stainless steel and diffusion hardened Ti-13Nb-13Zr were implanted in adult sheep, in one group (with unosteotomized femurs) for 16 weeks, and in the other (with osteotomized femurs) for 8 weeks. At harvest, the diffusion hardened Ti-13Nb-13Zr devices had superior fixation strength, with greater screw torque out strength and fewer loose screws. In the osteotomized animals, the femurs with diffusion hardened Ti-13Nb-13Zr plates had higher torsional strength after removal of the implants; however, the difference was not statistically significant. In the unosteotomized animals, the torsional strength of the femurs was identical for both materials. There was a slightly reduced incidence of infection (bacterial adhesion) for the sheep with diffusion hardened Ti-13Nb-13Zr implants. In a parallel in vitro study, the magnetic resonance imaging compatibility of Ti-13Nb-13Zr was significantly superior to that of stainless steel. This indicates that diffusion hardened Ti-13Nb-13Zr may be an attractive alternative material for osteosynthesis.

Spectrophotometric determination of natural indoles by complexing with 1,3,5-trinitrobenzene.

A spectrophotometric method has been developed for the quantitative determination of some natural indoles by complexing with the electron acceptor 1,3,5-trinitrobenzene and measuring the absorbance in the region 460-529 nm. The RSD of the method is 2.5%. It is simple, rapid and convenient for the routine analysis of indole compounds.

Spectrophotometric method of determination of natural indoles by coloured complexes.

A new spectrophotometric method has been developed for quantitative determination of naturally occurring indoles via electron donor-acceptor complexes with chloranil. The method is simple, precise and convenient for routine laboratory work. The analysis of each indole can be carried out within half an hour.