Osteoporotic hip fractures: 10-year review in a Singaporean hospital.

PURPOSE: To review records of 2702 patients with osteoporotic hip fractures in a Singaporean hospital. METHODS: Medical records of 1905 women and 797 men, aged 50 to 112 (median, 78) years, who were admitted to a Singaporean hospital with an osteoporotic hip fracture (ICD9 820) between January 2000 and December 2010 were reviewed. RESULTS: Female patients were significantly older than male patients (p<0.0005). The trend for the median patient age over the 10-year period has increased significantly in women (r=0.826, p=0.002) but not in men. Of the hip fractures, 49.4% were femoral neck fractures and 50.6% were intertrochanteric/ basicervical fractures. The rate of intertrochanteric/ basicervical fractures was higher in men than women (61.2% vs. 46.1%, p<0.0005). Increased age, ischaemic heart disease, Parkinson's disease, and being Malay or Caucasian or Sikh were more likely to have intertrochanteric/basicervical fractures than femoral neck fractures. Femoral neck fractures were usually treated with hemiarthroplasty (68.8%), cancellous screw fixation (20.6%), and conservative methods (20.5%), whereas intertrochanteric/basicervical fractures were usually treated with dynamic hip screw fixation (76.3%) and conservative methods (15.6%). 84 women and 26 men sustained a subsequent osteoporotic hip fracture on the contralateral side after a median interval of 2 (range, 0-8) years. 11 of these 110 patients were already on osteoporosis medication. CONCLUSION: The rate of osteoporotic hip fractures has increased, particularly among women, over the 10- year period. The rate of intertrochanteric/basicervical fractures was higher in men than women.

Improving stability of locking compression plates through a design modification: a computational investigation.

Femoral shaft fractures are common in both the young and elderly due to high-impact trauma and low-impact trauma, respectively. Its treatment by indirect reduction through use of locking compression plates (LCPs) has been on the rise. The LCP possess several advantages in fracture fixation, combining angular stability through use of locking screws with misalignment correction and fracture reduction onto the plate through use of conventional screws. However, there have been cases of plate breakage and fracture non-unions to warrant a study to improve its stability. A design modification is suggested for mid-diaphyseal fractures, whereby unused screw holes are removed. The structural stability of the modified and commercially available LCP is computationally analyzed using finite element modelling and a comparison made in terms of mechanical performance across different fracture lengths. A critical fracture length for which the commercially available LCP is functional as a fixator for mid-diaphyseal fractures was established. The maximum von Mises' stress attained by the commercially available LCP rose to as high as 105 MPa, whereas for the modified LCP, it did not exceed 25 MPa. As expected, these stresses were also found at screw holes, nearest to the fracture site. Critical fracture length allows clinicians to quantitatively distinguish between mid-diaphyseal fractures that can or cannot be treated by the use of LCP fixation. It is also believed that the proposed design modification will substantially increase the fatigue life of the fixator, especially at screw holes nearest to the fracture region, where most fatigue fractures are known to occur and will consequently be functional for greater fracture lengths.

Patients with knee osteoarthritis demonstrate improved gait pattern and reduced pain following a non-invasive biomechanical therapy: a prospective multi-centre study on Singaporean population.

BACKGROUND: Previous studies have shown the effect of a unique therapy with a non-invasive biomechanical foot-worn device (AposTherapy) on Caucasian western population suffering from knee osteoarthritis. The purpose of the current study was to evaluate the effect of this therapy on the level of symptoms and gait patterns in a multi-ethnic Singaporean population suffering from knee osteoarthritis. METHODS: Fifty-eight patients with bilateral medial compartment knee osteoarthritis participated in the study. All patients underwent a computerized gait test and completed two self-assessment questionnaires (WOMAC and SF-36). The biomechanical device was calibrated to each patient, and therapy commenced. Changes in gait patterns and self-assessment questionnaires were reassessed after 3 and 6 months of therapy. RESULTS: A significant improvement was seen in all of the gait parameters following 6 months of therapy. Specifically, gait velocity increased by 15.9%, step length increased by 10.3%, stance phase decreased by 5.9% and single limb support phase increased by 2.7%. In addition, pain, stiffness and functional limitation significantly decreased by 68.3%, 66.7% and 75.6%, respectively. SF-36 physical score and mental score also increased significantly following 6 months of therapy (46.1% and 22.4%, respectively) (P < 0.05 for all parameters). CONCLUSIONS: Singaporean population with medial compartment knee osteoarthritis demonstrated improved gait patterns, reported alleviation in symptoms and improved function and quality of life following 6 months of therapy with a unique biomechanical device. TRIAL REGISTRATION: Registration number NCT01562652.

The relationship between body mass index and physical activity levels in relation to bone mineral density in premenopausal and postmenopausal women.

UNLABELLED: We prospectively analyzed 283 women to evaluate the effects of body mass index (BMI) and physical activity levels on bone mineral density (BMD) progression in pre- and postmenopausal women over 2 years. In postmenopausal women, lower BMI was linked with worsening BMD, and moderate activity levels were associated with a lower likelihood of worsening BMD at 2 years. PURPOSE: The aim of our study is to evaluate the effects of BMI and physical activity levels on BMD progression in pre- and postmenopausal Asian women over 2 years. METHODS: We prospectively analyzed 283 women from 2006 to 2009. They were divided into two groups (159 pre- and 124 postmenopausal) and analyzed separately to avoid confounding by age and menopausal hormonal status. The mean follow-up period was 771 days. Demographic data was obtained, including medical history, calcium supplementation, BMI, and physical activity levels (IPAQ scale). Bilateral femoral neck BMD was determined at the time of recruitment, 1 year, and after 2 years. Generalized linear modeling was used to evaluate the effects of BMI and physical activity levels on BMD progression over a 2-year period. RESULTS: Amongst premenopausal women, lower initial femoral neck BMD scores were linked to worsening BMD (p = 0.048). In postmenopausal women, lower BMI was linked with worsening BMD (p = 0.012). Postmenopausal patients with moderate activity levels had a lower likelihood of worsening BMD at 2 years (p = 0.038). High physical activity levels were linked to a lower risk of BMD worsening (p = 0.066). CONCLUSIONS: Higher BMI scores are protective for osteoporosis in postmenopausal women. Moderate levels of physical activity are beneficial for bone health in postmenopausal women, while low physical activity levels are not helpful. We recommend that, in the secondary prevention of osteoporosis, postmenopausal women should be encouraged to participate regularly in moderate physical activities. A practical approach would be walking 30 min a day for at least 5 days per week.

A subtrochanteric femoral fracture 15 years after radiotherapy: a case report.

Pathological fracture is a rare but serious complication of radiotherapy. We report on a 44-year-old man who presented with a subtrochanteric femoral fracture 15 years after radiotherapy for a soft-tissue sarcoma in the thigh. We discuss its potential causes, a scoring system to identify high-risk patients for prophylactic intramedullary nailing of the femur, and radiographic signs to identify an impending insufficiency fracture.

Femoral canal obliteration secondary to prolonged alendronate use: a case report.

Insufficiency fractures secondary to prolonged alendronate use is due to inhibition of osteoclastic activity and suppressed bone turnover. Complications of fracture fixation include non-union, mal-union, and difficulty in intramedullary nail insertion. We report a technical challenge in intramedullary nailing of an obliterated femoral canal in a patient on long-term bisphosphonate treatment. The fracture site was explored. The medullary canal was re-created by drilling. Patience and caution during drilling and reaming are necessary to avoid iatrogenic fractures.

The susceptibility of the femoral neck to fracture: an assessment incorporating the effects of age-remodeling and stress reduction.

Age-related bone remodeling may cause fragility of the femoral neck, thereby increasing fracture risk in elderly populations. We investigated the effects of age-remodeling and stress-reduction on the femoral neck region using the Finite Strip Method (FSM). We verified the possibility that the femoral neck is likely to undergo fracture through two mechanisms: yielding and local buckling. We hypothesized that the femoral necks of young subjects are more prone to fracture by yielding, whereas those of elderly subjects are more susceptible to fracture initiated by local buckling. The slices from the CT-scans of 15 subjects corresponding to the lowest area moment of inertia were segregated into cortex and trabeculae. Geometric and material properties for each strip were obtained from the CT-scans. The FSM, proposed here as an approximation to the better-known Finite Element Method (FEM), was implemented on a model comprising both cortex and trabeculae. Finite strip (FS) analyses were performed on models that incorporated the effects of age-related bone remodeling, as well as a reduction in physiological stress on the bone (as a result of weight loss). Comparisons were made with similar FS analyses performed on only the cortical shell, in order to ascertain the contributions of the trabeculae to femoral neck strength. We observed that the femoral necks of simulated young subjects manifested a marked predisposition to undergo yielding, whereas the femoral neck models of simulated elderly subjects were more prone to buckling before yielding. The trabecular degradation and cortical thinning involved in aging render the femoral neck more susceptible to failure by buckling.

Clinical outcome following treatment of stable and unstable intertrochanteric fractures with dynamic hip screw.

INTRODUCTION: Intertrochanteric (IT) fractures are associated with significant morbidity and mortality in the elderly population. We aim to compare the clinical outcome of unstable with stable IT fractures after treatment with dynamic hip screw (DHS). MATERIALS AND METHODS: Patients with IT fractures treated with DHS at National University Hospital between 2003 and 2005 were included in the study. Patients were divided into 2 groups: stable and unstable IT fractures. Clinical outcome parameters include perioperative complications, functional outcomes, and incidence of morbidity and mortality. RESULTS: One hundred and thirty-six patients were analysed. Mean age was 77 years. There were 61 stable and 78 unstable fractures. Average length of follow-up was 30 months. The rates of local complications were not significantly different between the 2 groups. The incidence of malunion and excessive impaction were significantly higher in the unstable group. The ambulatory status at one year post-surgery was not significantly different between the 2 groups. In terms of general postoperative complications and one year mortality rate, there was no significant difference between the 2 groups. The need for blood transfusion was significantly higher in the unstable group. CONCLUSION: In summary, DHS fixation provides comparable postoperative outcomes in unstable IT fractures with relatively low rates of complications. Although it was associated with a higher incidence of malunion and excessive impaction in the unstable fracture group, there was no difference in functional status at one-year compared to the stable group.

Modified Mitchell's osteotomy for moderate to severe hallux valgus--an outcome study.

The purpose of this study was to evaluate the outcome of a modified technique of Mitchell's osteotomy for treatment of moderate to severe hallux valgus deformity with the aims of reducing first metatarsal shortening and osteonecrosis. Between February 2001 and December 2007, a total of 69 patients (90 feet) underwent Mitchell's corrective osteotomy for moderate to severe hallux valgus deformity. Mean duration of follow-up after surgery was 37 months. Clinical outcome was assessed using the AOFAS Hallux Metatarsophalangeal-Interphalangeal score preoperatively; at 6 weeks, 6 months, 12 months postoperatively; and at annual follow-ups thereafter. Standard weight-bearing radiographs were obtained at each visit. Fifty-nine patients (80/90 feet, 89%) were completely satisfied, whereas 10 patients (10/90 feet, 11%) were satisfied with minor reservations owing to minor complications. Global AOFAS score improved from 43.7 (range, 20 to 77) preoperatively to 85.4 (range, 55 to 100) at final follow-up (P < .01). Eighty-eight (98%) of 90 feet were completely pain free. There was a statistically significant improvement in mean hallux valgus angle, intermetatarsal angle, and distal metatarsal articular angle at final follow-up. There were no cases of deep infection, nonunion, or osteonecrosis of first metatarsal head. None of the patients had shortening of the first metatarsal bone by more than 3 mm. In conclusion, our modified surgical technique with a combination of bony correction and adequate capsular reefing is a simple procedure to correct moderate to severe hallux valgus deformity that results in high levels of patient satisfaction, successful deformity correction, and controlled shortening of the first metatarsal, as well as minimal recurrence of deformity.).

The ten-year pattern of hip diseases in Singapore.

PURPOSE: To review patients with hip diseases undergoing total hip arthroplasty (THA) during 2 different periods. METHODS: During the periods 1994 to 1996 and 2004 to 2006, 12 men and 28 women (mean age, 57 years) and 55 men and 78 women (mean age, 62 years) underwent THA for hip diseases, respectively. The aetiologies of the hip diseases were classified. Preand post-operative radiographs of the pelvis and hip were reviewed. The femoral head-tilt ratio (FHR) was measured. RESULTS: The number of patients undergoing THA increased 3-fold over 10 years; the proportion of different aetiologies was similar. Respectively, the most common aetiologies were acetabular dysplasia (33% vs. 40%) and avascular necrosis (33% vs. 42%). Only less than 5% of the patients had advanced osteoarthritis with no demonstrable cause, most of whom being Caucasians. The overall mean FHR was 1.07. There was no significant difference between male and female subjects. CONCLUSION: The pattern of hip diseases in Singapore remained similar over the 10-year interval, but the number of patients undergoing THA had increased 3-fold.

Medium-term outcome of total hip replacement for dysplastic hips in Singapore.

PURPOSE: To review medium-term outcomes of 46 patients who underwent total hip replacement (THR) for osteoarthritis secondary to dysplastic hips. METHODS: Records of 58 hips in 6 men and 40 women aged 32 to 76 (mean, 62) years who underwent THR for osteoarthritis secondary to dysplastic hips and had been followed up for a mean of 4 (range, 2-8) years were retrospectively reviewed. The hips were classified according to the Crowe's grading, Sharp's acetabular angle, and centre-edge angle. The radiological uncoverage of acetabular cup (RUAC) index was calculated. The outcomes of THR were evaluated in terms of cup inclination, RUAC index, cup migration, lysis or loosening (radiolucency), heterotopic ossification, component incorporation and positioning, thigh pain, and subsidence. RESULTS: 51 of the hips were Crowe's type I, 6 were type II, and one was type IV. The mean acetabular angle was 46.3 degrees and the mean centre-edge angle was 15.4 degrees. The mean cup, head, and stem sizes were 50.4 mm, 28.7 mm, and 10.9 mm, respectively. The mean RUAC index was 16.9% and the mean cup inclination was 40.7 degrees. Radiolucency of 1 mm in the acetabular zone I was observed in 16 cases, but only one failed. For cemented and uncemented stems, the most common positioning was neutral and valgus, respectively. Five patients had complications of greater trochanter fracture, aseptic loosening, split calcar, stem loosening, and/or heterotopic ossification. CONCLUSION: Conventional THR can achieve good medium-term results in low-grade dysplastic hips.

Fast tool for evaluation of iliac crest tissue elastic properties using the reduced-basis methods.

Computationally expensive finite element (FE) methods are generally used for indirect evaluation of tissue mechanical properties of trabecular specimens, which is vital for fracture risk prediction in the elderly. This work presents the application of reduced-basis (RB) methods for rapid evaluation of simulation results. Three cylindrical transiliac crest specimens (diameter: 7.5 mm, length: 10-12 mm) were obtained from healthy subjects (20 year-old, 22 year-old, and 24 year-old females) and scanned using microcomputed tomography imaging. Cubic samples of dimensions 5×5×5 mm(3) were extracted from the core of the cylindrical specimens for FE analysis. Subsequently, a FE solution library (test space) was constructed for each of the specimens by varying the material property parameters: tissue elastic modulus and Poisson's ratio, to develop RB algorithms. The computational speed gain obtained by the RB methods and their accuracy relative to the FE analysis were evaluated. Speed gains greater than 4000 times, were obtained for all three specimens for a loss in accuracy of less than 1% in the maxima of von-Mises stress with respect to the FE-based value. The computational time decreased from more than 6 h to less than 18 s. RB algorithms can be successfully utilized for real-time reliable evaluation of trabecular bone elastic properties.

Efficacy of bone marrow-derived stem cells in strengthening osteoporotic bone in a rabbit model.

Osteoporosis might be due to defects in mesenchymal stem cells (MSCs) that lead to reduced proliferation and osteoblast differentiation. We hypothesized that transplantation of MSCs into sites at risk for developing osteoporotic bone could improve bone structure and biomechanics. The aim of this study was to establish an osteoporosis rabbit model by ovariectomy (OVX), characterize the autologous MSCs from the OVX rabbits, and transplant the autologous MSCs into the OVX rabbits. MSCs harvested from bone marrow of normal and OVX rabbits were culture expanded and differentiated in osteogenic medium. Phenotypes were evaluated by collagen I immunostaining, von Kossa staining, and quantitative assays of bone-specific alkaline phosphatase (B-ALP) and osteocalcin (OCN). MSCs were transfected with green fluorescence protein (GFP) and implanted in the gluteus muscle to trace their fate in vivo. Cultured autologous MSCs from OVX rabbits were constructed in calcium alginate gels and then transplanted in the distal femurs. At 4 and 8 weeks after implantation, histomorphometrical and biomechanical analyses were performed on the samples. MSCs from OVX rabbits displayed higher B-ALP activity, but had similar OCN levels as compared to those from sham rabbits. After 8 weeks of implantation, more bone apposition was found in the MSC-alginate-treated group. Histomorphometry indicated increased trabecular thickness. Histology also illustrated improved microstructures with newly formed osteoids and enhanced trabecular thickness. In addition, biomechanical testing revealed stronger stiffness in the MSC-alginate treatment group. Therefore, this study implies that transplantation of MSCs can help to strengthen osteoporotic bone in rabbits.

Bone mineral density and hip axis length in Singapore's multiracial population.

Ethnic differences in bone density and hip geometry are known to exist, even within the same population. A recent study in Singapore showed that there were significant racial differences in hip fracture rates, with Chinese having the highest incidence of hip fractures. The aim of this study was to compare the bone mineral density (BMD) and hip axis length in Chinese, Malay, and Indian women. A total of 1575 women aged 20-59 yr were recruited, of which 77.6% (1222) were Chinese, 7.7% (122) Malays, and 14.7% (231) Indians. There was no significant difference in peak BMD of both lumbar spine and femoral neck among the three ethnic groups. However, in the older age group (50-59 yr), both Chinese and Malay women had significantly lower femoral neck BMD compared to Indian women. There was no significant loss in BMD of the lumbar spine between the second and fifth decades in all the three races. Between the second and fifth decade, Chinese and Malay women had significant bone loss in the femoral neck of 6.6% and 8.2%, respectively, whereas Indian women did not show any significant bone loss. Chinese women had significantly longer hip axis length compared to either Malay or Indian women (9.87 +/- 0.52 cm vs 9.67 +/- 0.49 cm; p < 0.005; and 9.69 +/- 0.55 cm, p < 0.05, respectively). The initial findings suggest racial differences in bone density and hip geometry exist in the local community. Future research should include prospective, longitudinal studies to determine the age-related bone loss in these three racial groups. It is also important to investigate the differences of spine and hip fracture rates and their relationship with bone density and hip axis length.

Cell-based therapy in the repair of osteochondral defects: a novel use for adipose tissue.

Mesenchymal stem cells are currently procured from periosteum and bone marrow. The procurement of stem cells from these sources is tedious and gives a low yield of cells. This study was aimed at circumventing these problems and allowing for a method that would be more acceptable in the clinical setting. Tissue for transplantation was harvested from a single New Zealand White rabbit. Cells were more readily obtained from adipose tissue than from bone marrow or periosteum. The present method also provided a better yield of cells through culture. In vitro studies were performed to assess the differentiation potential of these cells. Successful in vitro transformation into alternative mesenchymal cell lines including cardiomyocytes revealed these cells to have wide differentiation potential. Further characterization morphologically, immunohistochemically, and via gene transfection showed features consistent with mesenchymal stem cells. Cultured cells were then transplanted into defects created in the left medial femoral condyle. The femora were harvested at various intervals and the repair tissue was assessed. Gross osteochondral defect reconstitution and histological grading was superior to periosteum-derived stem cell repair and repair by native mechanisms. Biomechanically, the repair tissue approximated intact cartilage and was superior to osteochondral autografts and repair by innate mechanisms.