Spaceflight-induced Bone Loss: Is there an Osteoporosis Risk?

Currently, the measurement of areal bone mineral density (aBMD) is used at NASA to evaluate the effects of spaceflight on the skeletal health of astronauts. Notably, there are precipitous declines in aBMD with losses >10 % detected in the hip and spine in some astronauts following a typical 6-month mission in space. How those percentage changes in aBMD relate to fracture risk in the younger-aged astronaut is unknown. Given the unique set of risk factors that could be contributing to this bone loss (eg, adaptation to weightlessness, suboptimal diet, reduced physical activity, perturbed mineral metabolism), one might not expect skeletal changes due to spaceflight to be similar to skeletal changes due to aging. Consequently, dual-energy X-ray absorptiometry (DXA) measurement of aBMD may be too limiting to understand fracture probability in the astronaut during a long-duration mission and the risk for premature osteoporosis after return to Earth. Following a brief review of the current knowledge-base, this paper will discuss some innovative research projects being pursued at NASA to help understand skeletal health in astronauts.     

Is It Appropriate to Treat Sarcoma Metastases With Intramedullary Nailing?

Clinical Orthopaedics and Related Research® - Patients with primary bone and soft tissue sarcoma are at risk for skeletal metastases. Although uncommon, these metastases can result in...     

CORR Insights®: Is It Appropriate to Treat Sarcoma Metastases With Intramedullary Nailing?

Clinical Orthopaedics and Related Research® -     

Are Custom Triflange Acetabular Components Effective for Reconstruction of Catastrophic Bone Loss?

Background

Although the introduction of ultraporous metals in the forms of acetabular components and augments has increased the orthopaedic surgeon’s ability to reconstruct severely compromised acetabuli, there remain some that cannot be managed readily using cups, augments, or cages. In such situations, allograft-prosthetic composites or custom acetabular components may be called for. However, few studies have reported on the results of these components.

Questions/purposes

The purposes of this study were to determine the (1) frequency of repeat revision, (2) complications and radiographic findings, and (3) Harris hip scores in patients who underwent complex acetabular revision surgery with custom acetabular components.

Methods

Between August 2003 and February 2012, 26 patients (28 hips) have undergone acetabular reconstruction with custom triflange components. During this time, the general indications for using these implants included (1) failed prior salvage reconstruction with cage or porous metal construct augments, (2) large contained defects with possible discontinuity, (3) known pelvic discontinuity, and (4) complex multiply surgically treated hips with insufficient bone stock to reconstruct using other means. This approach was used in a cohort of patients with Paprosky Type 3B acetabular defects, which represented 3% (30 of 955) of the acetabular revisions we performed during the study period. Minimum followup was 2 years (mean, 57 months; range, 28–108 months). Seven patients (eight hips) died during the study period, and three (11%) of these patients (four hips; 14%) were lost to followup before 2 years, leaving 23 patients (24 hips) with minimum 2-year followup. Sixteen patients were women. The mean age of the patients was 67 years (range, 47–85 years) and mean BMI was 28 kg/m² (range, 23–39 kg/m²). Revisions and complications were identified by chart review; hip scores were registered in our institution’s longitudinal database. Pre- and postoperative radiographs were analyzed by the patient’s surgeon to determine whether migration, fracture of fixation screws, or continued bone loss had occurred.

Results

There have been four subsequent surgical interventions: two failures secondary to sepsis, and one stem revision and one open reduction internal fixation for periprosthetic femoral fracture. There were two minor complications managed nonoperatively, but all of the components were noted to be well-fixed with no obvious migration or loosening observed on the most recent radiographs. Harris hip scores improved from a mean of 42 (SD, ± 16) before surgery to 65 (SD, ± 18) at latest followup (p < 0.001).

Conclusions

Custom acetabular triflange components represent yet another tool in the reconstructive surgeon’s armamentarium. These devices can be helpful in situations of catastrophic bone loss.

Level of Evidence

Level IV, therapeutic study.     

Does a High Dietary Acid Content Cause Bone Loss,and Can Bone Loss Be Prevented With an Alkaline Diet?

A popular concept in nutrition and lay literature is that of the role of a diet high in acid or protein in the pathogenesis of osteoporosis. A diet rich in fruit and vegetable intake is thought to enhance bone health as the result of its greater potassium and lower “acidic” content than a diet rich in animal protein and sodium. Consequently, there have been a number of studies of diet manipulation to enhance potassium and “alkaline” content of the diet to improve bone density or other parameters of bone health. Although acid loading or an acidic diet featuring a high protein intake may be associated with an increase in calciuria, the evidence supporting a role of these variables in the development of osteoporosis is not consistent. Similarly, intervention studies with a more alkaline diet or use of supplements of potassium citrate or bicarbonate have not consistently shown a bone health benefit. In the elderly, inadequate protein intake is a greater problem for bone health than protein excess.     

Irrigation and Debridement for Early Periprosthetic Knee Infection: Is It Effective?

Background

Irrigation and debridement (I&D) is performed for early management of periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). Symptom reporting is a subjective measure and may miss direct management of PJI. Utilizing an objective time interval from index procedure to I&D may better inform treatment decisions.

Structured Ultrasonography Workshop for Breast Surgeons: Is It An Effective Training Tool?

Background  

Effective training is essential to ensure satisfactory performance in surgeon-performed ultrasonography (US) and guided breast needle biopsies (USGBB). This study aimed to determine the efficacy of conducting a structured workshop in the teaching of breast US application and in guided biopsy techniques.     

Endovascular Therapy: Is It Effective in the Diabetic Limb?

Reducing the risk of lower extremity amputation in diabetics is a top priority. To make progress in this area, we must bring all options to bear in the treatment of diabetic peripheral vascular disease. The "endovascular promise" of lower morbidity, while attaining the primary clinical goal (in this case, limb salvage), was late to arrive in the treatment of the ischemic diabetic lower extremity. This is due to complex and severe lesion morphologies requiring treatment, as well as the complexity of the vascular disease and the clinical scenario in diabetic critical limb ischemia. Although not without remaining challenges, significant strides have been made in the last 5 years that have increased the role of endovascular therapy in this setting.