Metal-on-metal hip resurfacing prostheses are a relatively recent intervention for relieving the symptoms of common musculoskeletal diseases such as osteoarthritis. While some short term clinical studies have offered positive results, in a minority of cases there is a recognised issue of femoral fracture, which commonly occurs in the first few months following the operation. This problem has been explained by a surgeon's learning curve and notching of the femur but, to date, studies of explanted early fracture components have been limited.

Tribological analysis was carried out on fourteen retrieved femoral components of which twelve were revised after femoral fracture and two for avascular necrosis (AVN). Eight samples were Durom (Zimmer, Indiana, USA) devices and six were Articular Surface Replacements (ASR, DePuy, Leeds, United Kingdom). One AVN retrieval was a Durom, the other an ASR. The mean time to fracture was 3.4 months. The AVNs were retrieved after 16 months (Durom) and 38 months (ASR).

Volumetric wear rates were determined using a Mitutoyo Legex 322 co-ordinate measuring machine (scanning accuracy within 1 micron) and a bespoke computer program. The method was validated against gravimetric calculations for volumetric wear using a sample femoral head that was artificially worn in vitro. At 5mm3, 10mm3, and 15mm3 of material removal, the method was accurate to within 0.5mm3. Surface roughness data was collected using a Zygo NewView500 interferometer (resolution 1nm).

Mean wear rates of 17.74mm3/year were measured from the fracture components. Wear rates for the AVN retrievals were 0.43mm3/year and 3.45mm3/year. Mean roughness values of the fracture retrievals (PV = 0.754nm, RMS = 0.027nm) were similar to the AVNs (PV = 0.621nm, RMS = 0.030nm), though the AVNs had been in vivo for significantly longer.

Theoretical lubrication calculations were carried out which found that in both AVN retrievals and in seven of the twelve cases of femoral fracture the roughening was sufficient to change the lubrication regime from fluid film to mixed. Three of these surfaces were bordering on the boundary lubrication regime. The results show that even before the femoral fracture, wear rates and roughness values were high and the implants were performing poorly.

The Nottingham Hip Fracture Score (NHFS) was developed in 2007 as a predictor of 30-day mortality after hip fracture surgery following a neck of femur fracture. The National Hip Fracture Database is the standard used which calculated their own score using national data. The NHF score for 30-day mortality was calculated for 50 patients presenting with a fractured neck femur injury between January 2020 to March 2020. A score <5 was classified as low risk and >/=5 as high risk. Aim was to assess the accuracy in calculating the Nottingham Hip Fracture Score against the National Hip Fracture Database. To explore whether it should it be routinely included during initial assessment to aid clinical management?. There was an increase in the number of mortalities observed in patients who belonged to the high-risk group (>=5) compared to the low risk group. COVID-19 positive patients had worse outcomes with average 30-day mortality of 6.78 compared to the average of 6.06. GEH NHF score per month showed significant accuracy against the NHFD scores. The identification of high-risk groups from their NHF score can allow for targeted optimisations and elucidation of risk factors easily gathered at the point of hospitalisation. The NHFS is a valuable tool and useful predictor to stratify the risk of 30-day mortality and 1-year mortality after hip fracture surgery. Inclusion of the score should be considered as mandatory Trust policy for neck of femur fracture patients to aid clinical management and improve patient safety overall

The covid-19 pandemic had a great impact in the daily clinical and surgical practice. Concerning patients with a femoral neck fracture, there is the need of a negative Sars-CoV-2 test or an established isolation period for the positive cases, pre-operatively. The goal of this study was to evaluate the impact of the pandemic in the management of patients with femoral neck fractures, who were submitted to surgical treatment with hemiarthroplasty, in our hospital. A retrospective, observational study was performed, analysing the patients with femoral neck fractures submitted to hip hemiarthroplasty, during the years 2019 (before the pandemic) and 2020 (first year of the pandemic). We analysed the first 5 patients operated in each month of the mentioned years. We analysed 56 and 60 patients submitted to surgery in the years 2019 and 2020, respectively. The inpatient days were, in average, 14.1 and 13.1. Patients were operated, in average, 3.0 and 3.8 days after admission (corrected to 2.5 and 3.6 days if the time of discontinuation of anticoagulants or antiplatelets needed before surgery is deducted). There were peri-operative complications in 53.6% and 46.7% of the patients, in 2019 and 2020 respectively. The most common complication in both groups was a low postoperative haemoglobin level needing red blood cell transfusion. One-year postoperative mortality rate was 17.9% and 13.3%, respectively. Despite the changes triggered by the new pandemic, there was an overall maintenance of the quality of the management of these patients, with only a slight increase in the interval between admission and surgery. Some of the remaining variables even showed an improvement when comparing the two groups of patients. Nevertheless, it is important to mention that there were patients infected with Covid-19 who died before being submitted to surgery, therefore not being present in these statistics

Abstract. Introduction. In general the life expectancy of population is improving. This is causing to increase case load of peri-prosthesis fractures after joint replacements. We present our results of peri-prosthesis fracture around hip managed by revision arthroplasty. Methods. A retrospective analysis of 24 consecutive patients of periprosthetic hip fracture treated with a revision arthroplasty at Major Trauma Centre between February 2021 and January 2022. Results. 12 male and 12 female patients, average age 78 years. 3 fractures around BHR prosthesis, 2 type A, 15 type B and 3 of type C (Vancouver). The surgery was done in an average 6 days after injury (range 1–14). 6 patients died in follow up, 1 patient contracted infection, 2 developed LLD and 1 patient had multiple dislocations. 6 patients had revision using endo-prosthesis. Advanced age with peri-prosthesis fracture has increased risk of mortality (average age 84.5 years). Conclusion. Endo-prosthesis replacement had higher risk of dislocation, infection and mortality. Overall patients do well after a revision arthroplasty for periprosthetic hip fracture. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction and Objective. Dislocation of a hip hemiarthroplasty is a significant complication with a high mortality rate in elderly patients. Previous studies have shown a higher risk of dislocation in patients with neuromuscular conditions. In this study, we reviewed our larger cohort of patients to identify if there is a link between neuromuscular disorders and dislocation of hip hemiarthroplasty in patients with neuromuscular conditions. Materials and Methods. We have retrospectively analysed a single-centre data that was collected over 34 years for patients with intracapsular neck of femur fracture who underwent hip hemiarthroplasty. The study population was composed of four groups: patients with no neuromuscular disorders, patients with Parkinson's disease, patients with previous stroke, and patients with mental impairment. Results. A total of 3827 patients were included in the analysis. 3371 patients had no neuromuscular condition (Group I) with a dislocation rate of 1.1%. 219 patients had Parkinsonism (Group II) with a dislocation rate of 3.2%, 104 patients had a previous stroke with weakness on the fracture side with a dislocation rate of 1.0% (Group III), and 984 patients had severe mental impairment with a dislocation rate of 1.8% (Group IV). The increased dislocation rate for those with Parkinson's disease was statistically significant (p=0.02) while none of the other neuromuscular conditions were statistically significant. Conclusions. Our study has shown an increased risk of dislocation of hemiarthroplasty in patients with Parkinson's disease in comparison to other groups. No increase was apparent for patients with mental impairment or weakness from a previous stroke

Introduction and Objective. Geriatric patients with a fragility fracture of the hip (FFH) are especially prone to sarcopenia with poor functional outcomes and quality of life. We assessed the prevalence of sarcopenia in older South African patients with FFH. Risk factors for sarcopenia were also investigated. Materials and Methods. From August 1 to November 30, 2018, all older patients with FFH were invited to participate. Sarcopenia was diagnosed based on the revised criteria of the European Working Group on Sarcopenia in Older People (EWGSOP2). Handgrip strength (HGS) and muscle strength were assessed. Muscle quantity was determined by dual-energy X-ray absorptiometry. Demographic information was collected, and 25-hydroxyvitamin D (25[OH]D) status was determined. Results. Of the 100 hip fracture cases, 65 were enrolled, and 52% (34/65) were sarcopenic (women: 62%; men: 38%). HGS accurately identified sarcopenia (sensitivity and specificity: 100%). Patients >80 years of age had a prevalence of sarcopenia twice (18/21 [83%]) that of younger patients (18/44 [36%]). Women with sarcopenia were smaller than those without (weight: p < 0.001; height: p < 0.001; body mass index: p¼0.018). Low 25(OH)D was almost universally present, with median 25(OH)D levels significantly lower in the patients with sarcopenia (27 nmol/L [interquartile range {IQR}: 20–39] vs. 40 nmol/L [IQR: 29–53]). Several risk factors, including advanced age; female sex; a smaller body size, especially among women; limited physical activity; and low 25(OH)D levels, were identified. Conclusions. The accuracy of HGS testing in this cohort underscores EWGSOP2's recommendation that muscle strength is key to sarcopenia. Further study and follow-up are required to determine the clinical relevance of sarcopenia among FFH patients. The prevalence of sarcopenia in our FFH population is high. Sarcopenia is associated with poor patient outcomes following surgical intervention. Orthopaedic surgeons should therefore be cognisant of the presentation and associated risk of sarcopenia as our patient populations age

Introduction and Objective. Individuals with type 2 diabetes (T2D) have a 3-fold increased risk of bone fracture compared to non-diabetics, with the majority of fractures occurring in the hip, vertebrae and wrists. However, unlike osteoporosis, in T2D, increased bone fragility is generally not accompanied by a reduction in bone mineral density (BMD). This implies that T2D is explained by poorer bone quality, whereby the intrinsic properties of the bone tissue itself are impaired, rather than bone mass. Yet, the mechanics remain unclear. The objective of this study is to (1) assess the fracture mechanics of bone at the structural and tissue level; and (2) investigate for changes in the composition of bone tissue along with measuring total fluorescent advanced glycation end products (fAGEs) from the skin, as T2D progresses with age in Zucker diabetic fatty (ZDF (fa/fa)) and lean Zucker (ZL (fa/+)) rats. Materials and Methods. Right ulnae and skin sections were harvested from ZDF (fa/fa) (T2D) and ZL (fa/+) (Control) rats at 12 and 46 weeks (wks) of age (n = 8, per strain and age) and frozen. Right ulnae were thawed for 12 hrs before micro-CT (μCT) scanning to assess the microstructure and measure BMD. After scanning, ulnae were loaded until failure via three-point bending. Fourier transform-infrared microspectroscopy (FTIR) was used to measure various bone mineral- and collagen-related parameters such as, mineral-to-matrix ratio and nonenzymatic cross-link ratio. Finally, fAGEs were measured from skin sections using fluorescence spectrometry and an absorbance assay, reported in units of ng quinine/ mg collagen. Results. At 12 and 46 wks bone size was significantly smaller in length (p < 0.01), cortical area (p < 0.001) and cross-sectional moment of inertia (p < 0.001) in T2D rats compared to age-matched controls. A slight reduction in BMD was observed in T2D rats compared to controls at both ages, however, this was not significant. Structural properties of T2D bone were significantly altered at 12 and 46 wks, with bending rigidity increasing approximately 2.5-fold and 1.5-fold in control and T2D rats with age, respectively (p < 0.0001). Similarly, yield and ultimate moment significantly reduced in T2D rats with age in comparison to controls (p < 0.0001). Energy absorbed to failure was significantly reduced in T2D rats at 46 weeks of age compared to controls (p < 0.01). The amount of energy absorbed to failure increased approximately 1.4-fold from 12 to 46 wks in control rats, however, in T2D rats a reduction was seen with age, although not significant. At 12 wks, there was no significant deficits in tissue material properties, whereas, at 46 wks a significant reduction in yield stress, yield strain and ultimate stress was observed for T2D rats in comparison to controls (p < 0.05). Conclusions. These findings show that longitudinal growth is impaired as early as 12 wks of age and by 46 wks bone size is significantly reduced in T2D rats compared to controls. The reduction in T2D structural properties is likely attributed to the bone geometry deficits. At 12 wks of age, the tissue material properties are not altered in T2D bone versus controls. However, at 46 wks, bone strength is reduced in T2D, leading to the conclusion that tissue properties are altered as the disease progresses

Introduction. The incidence of distal femoral fractures in the geriatric population is growing and represents the second most common insufficiency fracture of the femur following fractures around the hip joint. Fixation of fractures in patients with poor bone stock and early mobilisation in feeble and polymorbide patients is challenging. Development of a fixation approach for augmentation of conventional LISS (less invasive stabilization system) plating may result in superior long-term clinical outcomes and enhance safe weight bearing. Objectives. The aim of this study was to investigate the biomechanical competence of two different techniques of augmented LISS plating for treatment of osteoporotic fractures of the distal femur in comparison to conventional LISS plating. Materials & methods. Unstable distal femoral fracture AO/OTA 33-A3 was set in artificial femora with low density simulating osteoporotic bone. Three study groups, consisting of 10 specimens each, were created for instrumentation with a 9-hole LISS plate, a LISS plate with an additional 3D-printed polyactide cylindrical intramedullary graft, as well as a LISS plate plus a medial 3.5mm LCP (locking compression plate) - double plating. All specimens were non-destructively tested under axial (20–150N) and torsional (0–4Nm) quasi-static loading. Each construct was tested with two different working length (WL) configurations (long and short) of the LISS plate. Relative movements between the most medial superior and inferior osteotomy aspects were investigated via three-dimensional motion tracking analysis. Results. Interfragmentary displacement along the femur axis (mm) under 150N axial loading was 2.03±0.23/1.65±0.27 for LISS with long/short WL, 0.18±0.06/0.18±0.04 for double plating with long/short WL, and 0.40±0.05/0.30±0.05 for LISS plus graft with long/short WL. Shear interfragmentary displacement (mm) under 4Nm torsional loading in internal rotation was 1.16±0.17/0.92±0.11 for LISS with long/short WL, 0.40±0.10/0.43±0.07 for double plating with long/short WL, and 1.09±0.13/0.82±0.11 for LISS plus graft with long/short WL. Double plating revealed significantly smaller longitudinal and shear displacement compared to the other two techniques for long and short WL, respectively (P≤0.010). In addition, LISS plus graft fixation was with significantly less longitudinal displacement in comparison to conventional LISS plating for long and short WL, respectively (P≤0.001). Long WL resulted in significantly higher longitudinal and shear displacement compared to short WL for LISS and LISS plus graft (P≤0.032), but not for double plating (P=1.000). Conclusion. Intramedullary grafting resulted in significantly increased fracture stability under axial loading in comparison to conventional LISS plating. However, it was not efficient enough to achieve comparable stability to double plating

Reported rates of dislocation in hip hemiarthroplasty (HA) for the treatment of intra-capsular fractures of the hip, range between 1% and 10%. HA is frequently performed through a direct lateral surgical approach. The aim of this study is to determine the contribution of the anterior capsule to the stability of a cemented HA through a direct lateral approach. . A total of five whole-body cadavers were thawed at room temperature, providing ten hip joints for investigation. A Thompson HA was cemented in place via a direct lateral approach. The cadavers were then positioned supine, both knee joints were disarticulated and a digital torque wrench was attached to the femur using a circular frame with three half pins. The wrench applied an external rotation force with the hip in extension to allow the hip to dislocate anteriorly. Each hip was dislocated twice; once with a capsular repair and once without repairing the capsule. Stratified sampling ensured the order in which this was performed was alternated for the paired hips on each cadaver. . Comparing peak torque force in hips with the capsule repaired and peak torque force in hips without repair of the capsule, revealed a significant difference between the ‘capsule repaired’ (mean 22.96 Nm, standard deviation (. sd. ) 4.61) and the ‘capsule not repaired’ group (mean 5.6 Nm, . sd. 2.81) (p < 0.001). Capsular repair may help reduce the risk of hip dislocation following HA. Cite this article: Bone Joint J 2015;97-B:141–4

Displaced fractures of the neck of femur are routinely treated in the elderly by either cemented hemiarthoplasty, in the fit, or uncemented hemiarthroplasty, in the less fit. In Scotland the Scottish Intercollegiate Guidelines Network (SIGN) guidelines are followed to identify which patients should have a cemented prosthesis. This is based on cardiovascular status, and the age and fragility of the patient. An uncemented prosthesis should be a final operation. A peri-prosthetic fracture is considered a failure of treatment as the patient then has to undergo an operation with a far greater surgical insult. We looked at all neck of femur fractures over a period of Jan 2007 to June 2010. The number of the peri-prosthetic fractures for uncemented hip hemiarthroplasties was established, and a case note review was carried out. There was 1397 neck of femur fractures. 546 hemiarthroplasties were carried out, of which 183 were cemented, and 363 uncemented. 15 patients (4% of uncemented hemiarthoplasties) had peri-prosthetic fractures. There were no peri-prosthetic fractures in the cemented group, p = 0.004 using Fisher's exact test. The case notes of these patients were analysed. We found there was a common link of significant cardiovascular risk, lack of falls assessment (only 14% of the patients had a completed falls assessment and 21% sustained their fracture during an admission to hospital) and confusion (50% had a degree of dementia that caused significant confusion). Cemented implants should be considered in all patients, especially those who are cognitively impaired or have failed falls assessments; even if the cardiovascular risk is significant. This decision should be made in conjunction with a senior anaesthetist. This is being implemented in our unit and a prospective audit is being carried out over the same time period (July 2010 to Dec 2013) to assess the benefit

Displaced fractures of the neck of femur are routinely treated in the elderly by either cemented hemiarthoplasty, in the fit, or uncemented hemiarthroplasty, in the less fit. In Scotland the Scottish Intercollegiate Guidelines Network (SIGN) guidelines are followed to identify which patients should have a cemented prosthesis. This is based on cardiovascular status, and the age and fragility of the patient. An uncemeted prosthesis should be a final operation. A peri-prosthetic fracture is considered a failure of treatment as the patient then has to undergo an operation with a far greater surgical insult. We looked at all neck of femur fractures over a period of Jan 2007 to June 2010. The number of the peri-prosthetic fractures for uncemented hip hemiarthroplasties was established and a case note review carried out. There were 397 neck of femur fractures. 546 hemiarthroplasties were carried out, of which 183 were cemented, and 363 uncemented. 14 patients (4% of uncemented arthoplasties) had peri-prosthetic fractures. The case notes of these patients were analysed. There was a common link of significant cardiovascular risk, lack of falls assessment, and confusion. Cemented implants should be considered in those who have failed falls assessment, or are confused; even if the cardiovascular risk is significant. This decision should be made in conjunction with a senior anaethetist. This is being implemented in our unit and a prospective audit is being carried out over the same time period (July 2010 to Dec 2013) to assess the benefit

We compared joint proprioception in 12 hips in 12 patients with hemiarthroplasty after fracture of the hip, in 12 hips in 11 patients with total hip arthroplasty because of osteoarthritis and in a control group of 12 age-matched patients with no clinical complaints. There was no significant difference (p = 0.05) in joint proprioception in any of the groups. There was no decrease in joint proprioception in the group with total hip arthroplasty compared with the hemiarthroplasty group or with the control group. Other factors such as stretch receptors in the adjacent tendons and muscles may have a greater influence on proprioception in the hip than the intracapsular components

Introduction. Long-term use of bisphosphonates has been known to induce femoral insufficiency fracture in osteoporotic patients. We followed patients who had femoral insufficiency fractures after a long-term use of bisphosphonates. Methods. Eleven patients (14 hips) were diagnosed as having an insufficiency fracture of the femur after long-term (> 4 years) use of bisphosphonate to treat osteoporosis between January 2002 and December 2008. All patients were women who had a mean age of 68 years (range, 57 to 82 years). The fracture site was located in the subtrochanteric area in 6 hips and the femoral shaft in 8 hips. Three patients had bilateral involvement. These patients were followed-up for a mean of 27 months (range, 12 to 60 months). Results. Five hips in five patients displaced during the follow-up period. The mean period from the diagnosis of insufficiency fracture to the displacement was 10 months (range, 1 to 19 months). Five hips (five patients) underwent internal fixation due to persistent pain. Thus, during the follow-up of 27 months, operation was necessary in 71% (10 hips) of 14 insufficiency fractures. Four hips (four patients) that did not undergo any operation had persistent pain at the latest follow-up. Conclusion. The insufficiency fractures after prolonged bisphosphonate therapy seldom healed spontaneously and most of them required operation due to fracture displacement or persistent pain. We recommend preventive surgery to prevent further fracture displacement and persistent pain

Exeter Trauma Stem (ETS) is one of the most common implants used for treating displaced intracapsular hip fractures in the UK. We previously performed a radiographic audit of these implants which showed good placement was difficult. This was in particular relation to leg length discrepancy (LLD). This study reviewed the clinical outcomes of these patients, in particular looking at the relation of leg length discrepancy to outcome. We performed a clinical review of patients at 3 months and 1 year post ETS for hip fracture. Oxford hip score (OHS), Trendelenberg test, Visual Analogue Score (VAS) and walking aids required were recorded. Leg length discrepancy was determined radiographically on initial post op X-ray. This was recorded as Even (+/− 5mm), 6-10mm Long and >10mm long. Seventy-two patients were reviewed at 3 months and 21 at 1 year. Mean VAS was 1.6. At 3 months 66% were Trendelenberg positive. Of those Trendelenberg positive at 3 months only 42% remained positive at 1 year. Mean OHS at 3months and 1 year was 30.8 and 32.1 respectively. On radiographic review 38 implants were Even, 24 were 6-10mm Long and 10 implants were >10mm Long. There was no correlation between leg length discrepancy and either VAS or Trendelenberg test. 45 patients ambulated independently pre-op. Of these only 8 ambulated independently post-op, 18 used a stick and 11 a Zimmer frame. There was no correlation between post operative leg length discrepancy and either Visual Analogue Score, OHS or Trendelenberg test. Mean pain score was very low. There was however almost 10% of patients with a VAS greater than 6. 80% of patients dropped one ambulatory level post-op, this is consistent with previous studies. The ETS provides good pain relief with a low complication rate in the vast majority of patients

Introduction. Femoral neck fracture (FNF) is a common trauma in the elderly individuals. When the blood supply to the femoral head is impaired with a fracture event, the reduction or disruption of blood supply to the bone, hypoxia, leads to death of the bone marrow and trabecular bone, and eventual late segmental collapse. In the reparative process, osteoblasts and osteoclasts perform the important function of repairing the fracture site at the femoral neck. However, the reparative reaction including angiogenesis and osteogenesis remains unknown. In order to investigate the reparative reaction in patients with FNF, the distribution of tartrate resistant acid phosphatase (TRAP)-positive cells and expression of HIF-1 alpha, VEGF, and FGF-2 were observed in 36 hips in 35 patients. Methods. There were 6 men and 30 women who had a mean age of 79 years (range, 58 to 94 years). There were 10 hips with Garden stage 3, and 26 hips with Garden stage 4. The mean duration from onset to the surgery was 12 days (range: 1 to 82 days). Hematoxylin eosin staining, TRAP staining, immunohistochemistry using anti HIF-1 alpha, anti VEGF, and anti FGF-2 antibodies were performed for retrieved whole femoral heads. As a control, one femoral head in a patient who underwent wide resection for metastatic acetabular tumor was used. Results. TRAP-positive cells were detected in 9 hips (25%). They existed around the fracture site in 4 hips, while around the teres insertion and retinaculum in 7 hips. In the control, the TRAP-positive cells were detected slightly around the teres insertion and retinaculum. Around the fracture site, HIF-1 alpha expression was detected in 14 hips (39%) mainly at the vessel epithelium, VEGF was expressed at the edematous area in 28 hips (78%), while FGF-2 was detected widely in the marrow cells in 23 hips (64%). There were significant differences in TRAP staining and in HIF-1 alpha expression between Garden stage 3 and stage 4 hips, although there were no significant differences concerning the preoperative duration after fracture. Conclusion. TRAP-positive cells were recruited through the teres insertion and the retinaculum around the fracture site. HIF-1 alpha expression was detected at the restricted area around the fracture site, while VEGF and FGF-2 were detected widely regardless of Garden classification

Trauma and orthopaedics is the largest of the surgical specialties and yet attracts a disproportionately small fraction of available national and international funding for health research. With the burden of musculoskeletal disease increasing, high-quality research is required to improve the evidence base for orthopaedic practice. Using the current research landscape in the United Kingdom as an example, but also addressing the international perspective, we highlight the issues surrounding poor levels of research funding in trauma and orthopaedics and indicate avenues for improving the impact and success of surgical musculoskeletal research.

Cite this article: Bone Joint J 2014; 96-B:1578–85.

Objectives

This study aims to assess the correlation of CT-based structural rigidity analysis with mechanically determined axial rigidity in normal and metabolically diseased rat bone.

Objectives

To assess the sensitivity and specificity of self-reported osteoporosis compared with dual energy X-ray absorptiometry (DXA) defined osteoporosis, and to describe medication use among participants with the condition.

We investigated several factors which affect the stability of cortical screws in osteoporotic bone using 18 femora from cadavers of women aged between 45 and 96 years (mean 76). We performed bone densitometry to measure the bone mineral density of the cortical and cancellous bone of the shaft and head of the femur, respectively. The thickness and overall bone mass of the cortical layer of the shaft of the femur were measured using a microCT scanner. The force required to pull-out a 3.5 mm titanium cortical bone screw was determined after standardised insertion into specimens of the cortex of the femoral shaft.

A significant correlation was found between the pull-out strength and the overall bone mass of the cortical layer (r² = 0.867, p < 0.01) and also between its thickness (r² = 0.826, p < 0.01) and bone mineral density (r² = 0.861, p < 0.01). There was no statistically significant correlation between the age of the donor and the pull-out force (p = 0.246), the cortical thickness (p = 0.199), the bone mineral density (p = 0.697) or the level of osteoporosis (p = 0.378).

We conclude that the overall bone mass, the thickness and the bone mineral density of the cortical layer, are the main factors which affect the stability of a screw in human female osteoporotic cortical bone.