How to optimize patients for geriatric fracture surgery.

Low-energy fragility fractures account for >80% of fractures in elderly patients, and with aging populations, geriatric fracture surgery makes up a substantial proportion of the orthopedic workload. Elderly patients have markedly less physiologic reserve than do younger patients, and comorbidity is common. Even with optimal care, the risk of mortality and morbidity remains high. Multidisciplinary care, including early orthogeriatric input, is recommended to anticipate and treat complications. This article explores modern treatment strategies for this challenging group of patients and provides guidance for systematically preparing and optimizing elderly patients before surgery, based on best available current evidence and recommendations by relevant health organizations.

Venous thromboembolic prophylaxis for hip fractures.

Patients with hip fractures are at very high risk for the development of venous thromboembolism (VTE). To provide an overview of cause, risk factors, current treatment strategies, and complications associated with VTE prophylaxis, we reviewed the most current, best available evidence on VTE prophylaxis for patients with hip fractures. We comprehensively reviewed the literature to assess the efficacy of VTE prophylaxis in patients with hip fractures, including the most recent published guidelines by national medical and surgical health organizations from the UK, USA, and Canada. Mechanical devices are effective in reducing the risk of VTE for hip fracture, but poor patient compliance is common and the devices are not recommended for sole VTE prophylaxis. Aspirin reduces the risk of VTE but does not provide optimal protection compared with other chemical agents; therefore, it is not recommended for sole VTE prophylaxis. Fondaparinux, warfarin, low-molecular-weight heparin, and unfractionated heparin reduce the risk of venographic deep vein thrombosis, but there is insufficient evidence that they reduce fatal pulmonary embolism or all-cause mortality. Fondaparinux is considered to be cost effective and more efficacious than low-molecular-weight heparin. At present, most major health organizations advocate at least 28 days of postoperative chemical prophylaxis. Chemical VTE prophylaxis should be administered to all patients with hip fractures unless contraindicated. Additional research is required to establish an agent that has a significant impact on fatal pulmonary embolism and all-cause mortality, without increasing bleeding complications, in this group of patients.

Subsidence of uncemented stems in osteoporotic and non-osteoporotic cadaveric femora.

The increased use of uncemented stems for hip arthroplasty and of fast-recovery protocols in elderly patients make initial stem stability and resistance to fracture critical factors in osteoporotic bone. In this paper, the subsidence and failure of two uncemented stem designs (M/L Taper and VerSys Fullcoat, Zimmer, Inc, Warsaw, Indiana, USA) in osteoporotic and non-osteoporotic cadaveric femora were compared under simulated walking conditions (axial compression and external rotation). Osteoporotic femora implanted with either stem design failed significantly more frequently than did non-osteoporotic femora. Femora implanted with the M/L stems (seven of ten by 1000 cycles) fractured earlier than did femora implanted with the Fullcoat stem (one of ten by 1000 cycles). The use of early weight-bearing protocols with uncemented stem designs in osteoporotic bone should be approached with caution.

Biomechanical analysis of sacroplasty: does volume or location of cement matter?

BACKGROUND AND PURPOSE: Currently, the effect of the volume of cement used during sacroplasty on the restoration of pelvic strength and stiffness is unknown. The purpose of this study was to measure that effect in a sacral insufficiency fracture model. MATERIALS AND METHODS: Twenty-five osteoporotic cadaveric pelves were potted, and sacral fractures were produced. Specimens were divided into 4 groups: group 0 + 0 (control), no sacroplasty; group 3 + 0, sacroplasty (posterior approach), 3 mL of a bone cement injected bilaterally into the fracture site at S1; group 3 + 3, sacroplasty (posterior approach), 3 mL of the same cement injected bilaterally into the fracture site at S1 and S2; and group 6 + 3, sacroplasty (posterior approach), 6 mL of the same cement injected bilaterally at S1 and 3 mL injected bilaterally at S2. Cement position and extravasation were documented with CT. Specimens were tested to failure to assess the strength and stiffness after sacroplasty. RESULTS: There were no significant differences in strength or stiffness restoration between control and treatment groups. CONCLUSIONS: Sacroplasty does not restore the strength or stiffness of the sacrum in a cadaveric model regardless of the volume or location of cement.

Surgical treatment options for cartilage defects within the knee.

Injury to articular cartilage is increasingly diagnosed as a cause of knee pain. New surgical treatment options are now available to treat this clinical entity. Diagnosis is made easier by improved magnetic resonance imaging protocols that better visualize articular cartilage. On physical examination, patients at any age can have joint surface damage and primarily experience joint line tenderness and pain with activity. Treatment options include debridement of nonviable cartilage with abrasion or microfracture of the subchondral bone, transplantation of autologous osteochondral plugs, autologous chondrocyte transplantation, transplantation of cadaveric allogenic osteochondral grafts, and, for irreparable damage, total knee arthroplasty. These newer treatment options show promising early and intermediate results.

Formation of specific monosynaptic connections between muscle spindle afferents and motoneurons in the mouse.

In adult vertebrates, sensory neurons innervating stretch-sensitive muscle spindles make monosynaptic excitatory connections with specific subsets of motoneurons in the spinal cord. Spindle afferents (Ia fibers) make the strongest connections with motoneurons supplying the same (homonymous) muscle but make few or no connections with motoneurons supplying antagonistic or functionally unrelated muscles. In lower vertebrates these connections are specific from the time they first are formed, but there is comparatively little information about how these reflex connections form in mammals. We therefore studied the pattern of these synaptic connections during postnatal development in mice. Intracellular recordings were made from identified hindlimb motoneurons in an isolated spinal cord preparation, and monosynaptic inputs from Ia fibers in identified hindlimb muscle nerves were measured at different times during the first postnatal week. The pattern of connections was specific throughout this period. Ia fibers made strong connections with homonymous motoneurons but only weak connections with antagonistic motoneurons at every time point examined, from P0 through P7. Even when muscle nerves were stimulated at only 0.1 Hz, the pattern of connections was still highly specific, arguing against a special subpopulation of labile inappropriate connections. The absence of appreciable rearrangements in the pattern of these connections during the first postnatal week is, therefore, analogous to the situation in lower vertebrates, suggesting that mechanisms responsible for establishing this specificity have been conserved during evolution.

A critical period for the influence of peripheral targets on the central projections of developing sensory neurons.

During development, the projections that sensory neurons make within the spinal cord are influenced by the specific targets they contact in the periphery. If sensory ganglia normally supplying principally cutaneous targets are forced to grow into limb muscles, in early stage tadpoles, many sensory neurons within these ganglia innervate limb muscles and subsequently develop spinal projections appropriate for muscle spindle afferents. If the same procedure is performed with adult frogs, however, these novel projections do not form. In this study, we have determined the developmental stages at which this sensitivity to peripheral targets exists. Axons from sensory neurons in thoracic (largely cutaneous) dorsal root ganglia were re-routed into the front leg at various stages through metamorphosis, and the central spinal projections of these re-routed fibers were assessed with HRP labeling. We found that thoracic sensory axons could be made to project to limb muscles throughout development, but that the central projections of these neurons were only appropriate for spindle afferents if the fibers were re-routed before stage XVIII, shortly before metamorphic climax. Because sensory neurons can regenerate specifically into the appropriate spinal laminae even in adult frogs, these results suggest that changes in either the DRG or the arm musculature occur by stage XVII so that DRG neurons cannot respond to novel peripheral targets.

Specific regeneration of cutaneous sensory afferent fibers in the amphibian spinal cord.

Regeneration of cutaneous sensory fibers within the spinal cord was studied in frogs after lesions of sensory axons in dorsal roots. Sensory fibers were disrupted by repeatedly freezing the exposed brachial dorsal root in postmetamorphic frogs. Previous experiments indicated that this procedure destroyed virtually all sensory axons within the dorsal root. The pattern of regrowth of these fibers within the spinal cord was then assessed at different times by labeling them with horseradish peroxidase applied to the superior cutaneous ulnar nerve in the front leg. Arborizations of cutaneous axons within the spinal gray matter were remarkably similar to those in normal frogs. The arborizations were restricted to dorsal levels of the cord, never projecting ventrally to the region where muscle spindle sensory axons terminate. These experiments complement earlier studies demonstrating that muscle spindle afferents also regenerate specifically. Together these studies indicate that sufficient cues exist in the mature amphibian spinal cord to allow different classes of sensory fibers to reinnervate their appropriate target areas.