Diseases Affecting Bone Quality: Beyond Osteoporosis

Background  

Bone quantity, quality, and turnover contribute to whole bone strength. Although bone mineral density, or bone quantity, is associated with increased fracture risk, less is known about bone quality. Various conditions, including disorders of mineral homeostasis, disorders in bone remodeling, collagen disorders, and drugs, affect bone quality.     

Evaluation of proximal femoral geometry using digital photographs

The morphologic features of the proximal femur are used in preoperative planning prior to total hip arthroplasty. Recent literature evaluating the anatomy of the proximal femur, as it relates to total hip arthroplasty, has relied heavily on radiographs or computed tomography. We used digital photographs to compare 200 cadaveric femora in individuals who died prior to 40 years of age: 25 African‐American males, 25 African‐American females, 25 Caucasian males, 25 Caucasian females. With our technique and definition, the actual angles and dimensions of the proximal femur that we normally rely on during total hip arthroplasty were measured. There were small, but statistically significant differences, between males and females in neck‐shaft angle, neck inclination, and absolute horizontal and vertical offset. Females tended to have a lower neck‐shaft angle and more neck inclination. When standardizing the offset distances with femoral head diameter, the horizontal offset ratio was higher in female specimens. There was no correlation between horizontal and vertical offset. Improved knowledge of the morphology of the proximal femora will assist the surgeon in restoring the geometry of the proximal femur during total hip arthroplasty. This information also supports the concept of modularity of the femoral neck in order to independently adjust neck‐shaft angle, neck inclination, and horizontal offset. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1399–1404, 2010     

The Effect of Long-term Alendronate Treatment on Cortical Thickness of the Proximal Femur

Background  

One of the radiographic hallmarks in patients with atypical femoral insufficiency fractures after prolonged bisphosphonate treatment is generalized cortical hypertrophy. Whether cortical thickening in the proximal femur is caused by long-term alendronate therapy, however, remains unknown.     

Low Vitamin D Status Does Not Adversely Affect Short-Term Functional Outcome After Total Hip Arthroplasty

We prospectively measured functional performances (Western Ontario and McMaster Universities Osteoarthritis Index, Short Form-36, 2-minute walk test, and timed get-up-and-go test) of patients who underwent total hip arthroplasty (THA) and had serum vitamin D levels tested during the preoperative evaluation. Of 219 patients, 102 (46.6%) had low vitamin D levels (25-hydroxyvitamin D < 30 ng/mL). Low vitamin D status did not adversely affect short-term function at 6 weeks after THA. In addition, there was no association between serum vitamin D levels and the within-patient changes of scores of each outcome measurement. Because this 6-week period is generally adequate to correct vitamin D deficiency, orthopedic surgeons can safely perform THA without delay. Nevertheless, because vitamin D deficiency impairs bone quality, patients with low vitamin D levels should be treated once identified.     

Trunnion Fracture of the Anatomic Medullary Locking A Plus Femoral Component

Fracture of the neck of the femoral component after total hip arthroplasty is an infrequent complication. We present a report of 2 cases of trunnion fractures of fully porous-coated femoral stems (AML A Plus, DePuy International, Leeds, England), which had been implanted for 6 and 7 years after the index procedures. In both cases, failure emanated from a region where the trunnion had been intentionally grooved; and in both cases, the diameter of the trunnion was small, and evidence of corrosion contributing to the initiation of the failure was noted. Although this is the first report of trunnion fractures in this particular implant design, a close monitoring of prostheses with this specific trunnion should be considered. In addition, further analysis of clinical results and complications with this implant is warranted.     

A comprehensive approach to fragility fractures

To address the cause of fragility fractures, an understanding of the determinants of bone strength is needed. Identifying patients at increased fracture risk should take into account bone quantity, quality, and turnover. Postmenopausal osteoporosis remains the most common derangement of bone strength; however, decreased bone strength can also result from secondary causes of osteoporosis. In order to properly manage patients with fragility fractures, assessment should include a focused medical history and physical examination, proper laboratory investigation, dual-energy x-ray absorptiometry screening, and, if necessary, use of the fracture risk assessment tool (FRAX). Treatment options will include nonpharmacologic treatment such as calcium and vitamin D and pharmacologic treatment with antiresorptive or anabolic agents to prevent future fractures. Bisphosphonates remain the standard treatment for osteoporosis. Concerns of oversuppression of bone turnover on long-term bisphosphonate treatment can be addressed with a drug holiday depending on the patient's fracture risk. An anabolic agent such as teriparatide is a powerful tool for the prevention of fragility fractures and should be reserved for patients at high risk for fracture, such as those with declining bone mineral density despite bisphosphonate treatment. Careful evaluation of all patients with a fragility fracture will enable the orthopaedic surgeon to identify the cause of fracture and implement a treatment plan that can prevent subsequent fractures in this vulnerable population.     

Does Vitamin D Status Affect the Attainment of In-Hospital Functional Milestones After Total Hip Arthroplasty?

Our study aims to identify the prevalence of low vitamin D status in patients undergoing total hip arthroplasty (THA) and to evaluate the association between serum vitamin D level and the attainment of in-hospital functional milestones. We collected data from patients who underwent THA and had preoperative serum vitamin D (serum 25-hydroxy vitamin D) levels measured. From 200 patients, 79 (39.5%) had low serum vitamin D (serum 25-hydroxy vitamin D <32 ng/mL). There were no associations between serum vitamin D level and the attainment of in-hospital functional milestones as well as length of hospital stay or perioperative complications after THA. Because low vitamin D status did not compromise the short-term functional outcomes after THA, surgery need not be delayed, but low vitamin D levels should be corrected once identified.     

The accuracy of preoperative templating in cementless total hip arthroplasty

We evaluated the accuracy and clinical usefulness of preoperative templating in 109 cementless total hip arthroplasties. The size of the prosthesis was exactly predicted in 46 (42.2%) acetabular and 75 (68.8%) femoral components. The accuracy increased to greater than 90% if the prosthesis size was within 1 or 2 sizes (above or below) for femoral component and acetabular components, respectively. Having a contralateral total hip arthroplasty as a guide for preoperative templating was associated with greater accuracy in predicting the femoral component size only. Eighty-eight percent of the acetabular components were oriented inside the presumed safe range for inclination; 42% of the acetabular components were in the presumed safe range of anteversion. The mean postoperative leg length discrepancy was 0.9 +/- 6.8 mm; 93.5% had a discrepancy within 10 mm.     

Validity and Responsiveness of the Two-Minute Walk Test for Measuring Functional Recovery After Total Knee Arthroplasty

Background

The 2-minute walk test (2mwt) is a performance-based test that evaluates functional recovery after total knee arthroplasty (TKA). This study evaluated its validity compared with the modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), modified Knee Score, Numerical Pain Rating Scale, and Timed Up and Go test, and its responsiveness in assessing functional recovery in TKA patients.