The effect of the comorbidity burden on vitamin D levels in geriatric hip fracture.

BACKGROUND: Elderly patients with hip fractures often have multiple medical comorbidities, and vitamin D deficiency is common in this population. Accumulating evidence links low vitamin D levels to various comorbidities. However, very little is known about the collective impact of comorbidities on vitamin D levels. The Charlson Comorbidity Index (CCI) is a validated comorbidity burden index. We hypothesized that a high CCI score is associated with vitamin D deficiency in elderly patients with hip fracture. METHODS: A retrospective cohort study was conducted among all hospitalized elderly patients aged > 60 years admitted for low-energy hip fracture in a single tertiary hospital from 2013 to 2015. Data regarding patient demographics, fracture type, serum 25-hydroxyvitamin D3 levels and age-adjusted CCI score were collected and analysed. RESULTS: Of the 796 patients included in the study, 70.6% (n = 562) of the patients were women and the mean age was 77.7 ± 8.0 years. The mean vitamin D level was 20.4 ± 7.4 ng/mL, and 91.7% ofhospitalized elderly patients with hip fracture had inadequate vitamin D level. There was no correlation between the individual serum vitamin D level with respect to age-adjusted CCI (Pearson correlation coefficient = 0.01; p = 0.87). After stratifying the CCI scores into low and high comorbidity burden groups (i.e., with scores 1-2 and ≥ 3), there was no relationship between the 2 subgroups for age-adjusted CCI and vitamin D levels (p = 0.497). Furthermore, there was also no association among age, gender, fracture type, and smoking status with the mean 25(OH)D level (p > 0.05). CONCLUSION: Low vitamin D levels were highly prevalent in our hip fracture cohort. There was no relationship between the CCI score and vitamin D levels in the geriatric hip population. The comorbidity burden in geriatric patients with hip fractures did not seem to be a significant factor for vitamin D levels.

A Case Report of Mixed Osteomalacia and Low Bone Density from Vitamin D Deficiency as a Cause of Bilateral Tibial Stress Fractures in a Young Male Military Recruit from Singapore.

Despite being a tropical country, vitamin D deficiency is common in Singapore. All young Singaporean males between the age of 18 and 21 years have to undergo mandatory military service. Stress fractures occur in military recruits, and risk factors include a sudden increase in physical activity and vitamin D deficiency. We report the bone histomorphometry findings from a case of bilateral tibial stress fractures in an 18-year-old military recruit who had vitamin D deficiency. The histomorphometry showed a mixed osteomalacia and osteoporosis pattern. This case is unique as it shows that stress fractures from a marching exercise can occur in apparently healthy well young man with vitamin D deficiency despite living in a tropical country.

Predictors of failure following fixation of intertrochanteric fractures with proximal femoral nail antirotation.

INTRODUCTION: This retrospective matched case-control study aimed to identify predictors of cut-out following intramedullary nailing of intertrochanteric fractures with the 200-mm Synthes proximal femoral nail antirotation (PFNA). METHODS: 609 patients underwent intramedullary nailing for intertrochanteric fractures at our institution between January 2011 and December 2014. 370 patients satisfied the inclusion criteria. There were 20 cases of implant cut-out. Cases and controls were matched using a propensity score-matching method with an m:n ratio, matching the criteria of gender, age and side of operation. Radiographs were assessed to determine fracture classification, fracture reduction quality, tip-apex distance, calcar referenced tip-apex distance (CalTAD), anteroposterior (AP) Parker's ratio index, lateral Parker's ratio index and cervical angle difference. Conditional logistic regression analysis was performed to determine any association between potential predictors and cut-outs. RESULTS: The cut-out incidence was 5.4%. Of the 20 cut-outs, 16 were superior and four were cut-throughs. Univariate analysis only showed a significant association between unsatisfactory fracture reduction quality and cut-outs (odds ratio [OR] 10.1, 95% confidence interval [CI] 1.31-77.6, p = 0.027). This association remained significant with multivariate logistic regression analysis (OR 16.4, 95% CI 1.9-140.4, p = 0.011). Cut-throughs had significantly lower CalTAD (16.2 vs. 27.5, p = 0.016) and AP Parker's ratio index values (38.7 vs. 50.7, p = 0.007) than superior cut-outs. CONCLUSION: Unsatisfactory fracture reduction quality was a significant predictor of cut-out in intertrochanteric fractures treated with the 200-mm PFNA. Cut-outs had two distinct modes, with cut-throughs having a deeper and more inferior helical blade position in the femoral head compared to superior cut-outs.

Bone cross-sectional geometry is not associated with atypical femoral fractures in Asian female chronic bisphosphonate users.

INTRODUCTION: Atypical femoral fractures (AFF) tend to occur in Asian women with prolonged bisphosphonate exposure. Hip geometry is thought to contribute to the risk of AFF formation. We examined the hip structural geometry parameters in Asian female chronic bisphosphonate users who sustained an AFF and compared them to chronic bisphosphonate users who did not sustain any femoral fracture (NFF) and bisphosphonate-naïve patients who sustained an osteoporotic femoral fracture (OFF). MATERIALS & METHODS: Thirty-one patients with AFFs were gender and age-matched to 31 patients with NFFs and 49 patients with OFFs. The Hip Structural Analysis parameters analyzed were bone mineral density (BMD), cross-sectional area (CSA; a metric of resistance to axial compression), section modulus (SM; a metric of resistance to tensile loads), average cortical thickness (ACT; mean thickness of the femoral cortices), buckling ratio (BR; an index of likelihood of local buckling), and neck shaft angle (NSA; the angle between the neck and shaft axes). The regions analyzed were three cross-sections measured at the narrowest femoral neck diameter, the intertrochanteric area, and the proximal femoral shaft. One-way ANOVA with Bonferroni adjustment for multiple comparisons was used to compare parameters between the three patient groups, with statistical significance defined as p<0.05. RESULTS: There were no statistical differences in parameters between patients with AFFs and patients with NFFs at all measured regions. Patients with AFFs and NFFs had statistically higher BMD, CSA, ACT, SM values and lower BR values at the NN and IT regions than patients with OFFs. Additionally, patients with NFFs had statistically higher SM values at the IT region than patients with OFFs, while patients with AFFs had statistically higher BMD, CSA, and ACT values at the FS region. All other measured parameters were not statistically different between the groups. CONCLUSIONS: Chronic bisphosphonate users with and without AFFs had similar femoral structural geometries. Unlike in other populations, varus neck shaft angles were not found to be associated with AFFs in Asian female chronic bisphosphonate users. Thus, bone cross-sectional geometry is not likely to be associated with AFFs in Asian female chronic bisphosphonate users. Hip Structural Analysis does not show an increased predilection for tensile failure in AFFs.

Bisphosphonate-associated peri-implant fractures: a new clinical entity? A series of 10 patients with 11 fractures.

BACKGROUND AND PURPOSE: The current definition of atypical femoral fractures (AFFs) associated with bisphosphonate use includes only de novo fractures. However, in recent years reports of bisphosphonate-associated periprosthetic fractures involving stemmed arthroplasty implants have emerged. In a case series of peri-implant fractures in femurs with plate/screw constructs, we aimed to assess similarities with classical AFFs and how their location may have implications for the pathogenesis and management of AFFs. PATIENTS AND METHODS: We retrospectively identified 10 patients with 11 peri-implant fractures. RESULTS: The patients were ambulant women, mean age 80 (70-92) years. Mean duration of bisphosphonate use was 5 (1-10) years. The peri-implant fractures were sustained an average of 4 years (6 months to 9 years) from the time of index surgery. They were all associated with low-energy mechanisms. 8 fractures occurred near the tip of a plate, while 3 traversed the penultimate screwhole of a plate. The peri-implant fractures showed clinical and radiological features of atypicality such as lateral cortical thickening, simple fracture pattern, and lack of comminution. The patients underwent revision surgery, with bone grafting used in all but 1 case. Radiological union was evident after 2-4 months. INTERPRETATION: Atypical peri-implant fractures of the femur associated with bisphosphonate use may be a new entity. Stress lesions and atypical fractures may tend to develop over stress risers along the operated femur. This finding has implications for the pathogenesis and clinical management of AFFs.