Failure after osteosynthesis of trochanteric fractures. Where is the limit of osteoporosis?

Finite element analysis of proximal femur bionic nail for treating intertrochanteric fractures in osteoporotic bone

This study compared the biomechanical characteristics of proximal femur bionic nail (PFBN) and proximal femoral nail antirotation (PFNA) in treating osteoporotic femoral intertrochanteric fractures using finite element analysis. Under similar bone density, the PFBN outperforms the PFNA in maximum femoral displacement, internal fixation displacement, stress distribution in the femoral head and internal fixation components, and femoral neck varus angle. As the bone density decreases, the PFBN's biomechanical advantages over PFNA become more pronounced. This finding suggests that the PFBN is superior for treating osteoporotic intertrochanteric femoral fractures.

Short versus long intramedullary nails for intertrochanteric hip fracture: Meta-analysis

OBJECTIVE

To compare short versus long intramedullary nails for intertrochanteric hip fractures in terms of efficacy and safety.

METHODS

We included cohort studies and randomized clinical trials. The methodological quality of the studies was assessed by the Newcastle-Ottawa Scale. The meta-analysis was performed using the Review Manager 5.4. Heterogeneity was checked with the I2 test. A fixed effects model was adopted if there was no heterogeneity.

RESULTS

Twelve studies were included. The reoperations rate was lower in the short nail group (OR: 0.58, 95%CI: 0.38-0.88) and there were no differences regarding the peri-implant fracture rate (OR: 1.77, 95%CI: 0.68-4.60). Surgery time and blood loss was significantly higher in the long nail group (MD: -12.44, 95%CI: -14.60 -10.28) (MD: -19.36, 95%CI: -27.24 -11.48). There were no differences in functional outcomes.

CONCLUSIONS

The long nail showed a higher reoperation rate, blood loss and surgery time compared to the short nail.

LEVEL OF EVIDENCE

III.

Peri-implant distal radius fracture due to car collision

Peri-implant fractures have gained increasing importance in orthopedics as the number of surgical procedures involving orthopedic implants rises globally. These fractures pose a significant challenge in terms of diagnosis, treatment, and postoperative management. They manifest as stress fractures distal to the implant site. Developing an effective treatment strategy involves evaluating multiple influencing factors. This article presents a rare case of a peri-implant distal radius fracture in a 63-year-old man, with no comorbidities, resulting from a car accident, classified as C1U in the Michele D'Arienzo system. The surgical intervention included plate fixation for the radius and wire fixation for the ulna. The wire was used for ulna instead of a plate, due to skin injuries, with good results. As life expectancy rises and individuals remain active in their elder years, the incidence of peri-implant fractures is expected to increase. Factors such as the implant type, surgeon's approach, and patient-specific elements may influence peri-implant fracture occurrence. The widespread use of plate fixation for distal radius fractures may also contribute to a parallel increase in such fractures. Providing detailed context and specific case presentation allows better understanding and implications for clinical practice.

Short versus long intramedullary nails for intertrochanteric hip fracture: Meta-analysis

OBJECTIVE

To compare short versus long intramedullary nails for intertrochanteric hip fractures in terms of efficacy and safety.

METHODS

We included cohort studies and randomized clinical trials. The methodological quality of the studies was assessed by the Newcastle-Ottawa Scale. The meta-analysis was performed using the Review Manager 5.4. Heterogeneity was checked with the I2 test. A fixed effects model was adopted if there was no heterogeneity.

RESULTS

Twelve studies were included. The reoperations rate was lower in the short nail group (OR 0.58, 95% CI 0.38-0.88) and there were no differences regarding the peri-implant fracture rate (OR 1.77, 95% CI 0.68-4.60). Surgery time and blood loss was significantly higher in the long nail group (MD -12.44, 95% CI -14.60 to (-10.28)) (MD -19.36, 95% CI -27.24 to (-11.48)). There were no differences in functional outcomes.

CONCLUSIONS

The long nail showed a higher reoperation rate, blood loss and surgery time compared to the short nail.

Outcomes After Revision Fixation With Cement Augmentation for Failed Intertrochanteric Fracture Fixation in Older Adult Patients

Introduction

Intertrochanteric (IT) fractures that fail fixation are traditionally treated with arthroplasty, introducing significant risk of morbidity and mortality in frail older adult patients. Revision fixation with cement augmentation is a relatively novel technique that has been reported in several small scale international studies. Here we report a clinical series of 22 patients that underwent revision fixation with cement augmentation for IT fracture fixation failure.

Methods

This retrospective case series identified all patients that underwent revision intramedullary nailing from 2018 to 2021 at two institutions within a large metropolitan healthcare system. Demographics, injury characteristics, Charlson Comorbidity Index score, and surgical characteristics were extracted from the electronic medical record. Outcomes were extracted from the electronic medical record and included radiographic findings, pain, functional outcomes, complications, and mortality.

Results

Average follow-up after revision surgery was 15.2 ± 10.6 months. Twenty patients (90.9%) reported improved pain and achieved union or progressive healing after surgery. Most of these patients regained some degree of independent ambulation (19 patients, 86.4%), with only 5 patients (22.7%) requiring increased assistance for their activities of daily living (ADLs). One-year mortality was 13.6% (3 patients). Of the 5 patients (22.7%) that experienced complications, 2 patients (9.1%) required revision hemiarthroplasty for subsequent fixation failure. The other 3 patients did well when complications resolved.

Conclusions

Revision fixation with cement augmentation can be an effective, safe, cost-effective alternative to arthroplasty for the management of cases involving non-infected failed IT fracture fixation with implant cut-out or cut-through limited to the femoral head in older adult patients that have appropriate acetabular bone stock.

Indications for cement augmentation in fixation of geriatric intertrochanteric femur fractures: a systematic review of evidence

INTRODUCTION

Achieving durable mechanical stability in geriatric intertrochanteric proximal femur fractures remains a challenge. Concomitant poor bone quality, unstable fracture patterns, and suboptimal reduction are additional risk factors for early mechanical failure. Cement augmentation of the proximal locking screw or blade is one proposed method to augment implant anchorage. The purpose of this review is to describe the biomechanical and clinical evidence for cement augmentation of geriatric intertrochanteric fractures, and to elaborate indications for cement augmentation.

METHODS

The PubMed database was searched for English language studies up to January 2021. Studies that assessed effect of calcium phosphate or methylmethacrylate cement augmentation during open reduction and internal fixation of intertrochanteric fractures were included. Studies with sample size < 5, nontraumatic or periprosthetic fractures, and nonunion or revision surgery were excluded. Study selection adhered to PRISMA criteria.

RESULTS

801 studies were identified, of which 40 met study criteria. 9 studies assessed effect of cement augmentation on fracture displacement. All but one found that cement decreased fracture displacement. 10 studies assessed effect of cement augmentation on total load or cycles to failure. All but one demonstrated that augmented implants increased this variable. Complication rates of cement augmentation during ORIF of intertrochanteric fractures ranged from 0 to 47%, while non-augmented implants ranged from 0 to 51%. Reoperation rates ranged from 0 to 11% in the cement-augmented group and 0 to 11% in the non-augmented group. Fixation failure ranged from 0 to 11% in the cement-augmented group and 0 to 20% in the non-augmented group. Nonunion ranged from 0 to 3.6% in the cement-augmented group and 0 to 34% in the non-augmented group.

CONCLUSIONS

Calcium phosphate or PMMA-augmented CMN fixation of IT fractures increased construct stability and improved outcomes in biomechanical and early clinical studies. The findings of these studies suggest an important role for cement augmentation in patient populations at high risk of mechanical failure.

Comparison Between Femoral Neck Systems and Cannulated Cancellous Screws in Treating Femoral Neck Fractures: A Meta-Analysis

Background

We performed a meta-analysis to compare the efficacy and safety of the femoral neck system (FNS) with cannulated cancellous screws (CCSs) in treating femoral neck fractures (FNFs) in controlled clinical trials.

Methods

Eligible scientific articles published prior to September 2021 were retrieved from the PubMed, Web of Science, Springer, ScienceDirect and Cochrane Library databases. The statistical analysis was performed with RevMan 5.1.

Results

Seven retrospective studies met the inclusion criteria. Meta-analysis showed that there were significant differences in perioperative blood loss, the postoperative Harris score, healing time, fluoroscopy frequency, total complications, femoral head necrosis, femoral neck shortening and screw cutout. No significant differences were found regarding operation time, length of hospital stay or nonunion between the two groups.

Conclusion

Compared with CCSs, the FNS showed better clinical efficacy and fewer complications in treating FNFs. Due to the limited quality and data of the currently available evidence, more high-quality randomized controlled trials are needed.

Cement augmentation of the proximal femoral nail antirotation for the treatment of two intertrochanteric fractures - a comparative finite element study

BACKGROUND

There are concerns regarding initial stability and cutout effect in proximal femoral nail antirotation (PFNA) treating intertrochanteric fractures. No study have used finite element analysis (FEA) to investigate the biomechanics. This study aimed to compare the cutout effect, stress and displacement between stable (AO31-A1.3) and unstable (AO31-A2.2) intertrochanteric fractures treated by cement augmented PFNA.

METHODS

Four femoral finite element models (FEMs) were constructed and tested under the maximum loading during walking. Non-augmented and augmented PFNA in two different intertrochanteric fractures were respectively simulated, assuming Tip Apex Distance (TAD) < 25 mm within each FEM. The cutout effect, stress and displacement between femur and PFNA were compared in each condition.

RESULTS

Cutout effect was observed in both non-augmented femoral head and was more apparently in unstable intertrochanteric fracture model. After reinforced by bone cement, no cutout effect occurred in two models. Stress concentration were observed on medial part of intertrochanteric region and the proximal part of helical blade before augmented while were observed on femoral shaft and the conjunction between blade and nail after augmented in both FEMs. Displacement mainly appeared on femoral head and the helical blade tip before augmented while distributed moderately on intertrochanteric region and the upper part of nail after augmented in both FEMs. The maximum stress and displacement value of femur decreased both in stable and unstable model after augmented but was more significantly in the unstable one. The maximum stress and displacement value of PFNA increased both in stable and unstable model after augmented but was more significantly in the unstable one.

CONCLUSION

Our FEA study indicated that the cement augmentation of the PFNA biomechanically enhances the cutout resistance in intertrochanteric fracture, this procedure is especially efficient for the unstable intertrochanteric fracture.

Biodegradable cement augmentation of gamma nail osteosynthesis reduces migration in pertrochanteric fractures, a biomechanical in vitro study

BACKGROUND

Cut-out of gamma nail often results from poor primary bone stability, suboptimal reduction (varus) and excentric placement of the head element which may lead to "instability" and frequently requires revision. Various studies have shown that augmentation with polymethylmethacrylate cement increases the primary stability of osteosynthesis. However, it has not yet been widely used in fracture treatment due to certain disadvantages, e.g., the lack of osteointegration, the formation of an interface membrane or the presence of toxic monomers. Few studies show that biodegradable bone cements increase the stability of osteosynthesis in different anatomical regions and therefore could be an alternative to polymethylmethacrylate cement in the treatment of pertrochanteric fractures.

METHODS

Two biomechanical situations were simulated using 24 Sawbones (simple and multifragmentary pertrochanteric fractures; AO-classification 31-A1 and 31-A2. Both groups were stabilized using the Gamma3® nailing system with and without biodegradable bone cement. Sawbones underwent the same cyclic loading test, simulating 10.000 gait cycles loading the bones with three times body weight. Migration was determined by comparing computed tomography scans recorded before and after the mechanical testing. The three-dimensional migration of the lag screw was calculated, and the rotation of the head around the longitudinal axis was determined.

FINDINGS

Biodegradable cement reduced migration by approximately 35% in 31-A1 fractures (25.4% in 31-A2 fractures) and the rotation of the head around the lag screw by approximately 37% in 31-A1 fractures (17.8%, 31-A2).

INTERPRETATION

Use of biodegradable bone cement improved the primary stability of gamma nail osteosynthesis in the biomechanical model.

Positive or negative anteromedial cortical support of unstable pertrochanteric femoral fractures: A finite element analysis study

OBJECTIVE

To explore the mechanical stability of unstable pertrochanteric fractures with proximal femoral nail anti-rotation (PFNA-Ⅱ) fixation under different anteromedial cortical support reduction patterns.

METHODS

A 65-year-old healthy male volunteer with no history of hip or systemic disease was recruited. High-resolution computed tomography images with a slice thickness of 0.67 mm of his right femur were obtained. These images were used to establish three-dimensional (3D) models. The lesser trochanter and lateral femoral wall were cut off to create an AO Foundation/Orthopaedic Trauma Association type 31-A2 unstable pertrochanteric fracture model. PFNA-Ⅱ was used to simulate fixation. Nine different fracture reduction patterns, which included positive-positive, positive-neutral, positive-negative, neutral-positive, neutral-neutral, neutral-negative, negative-positive, negative-neutral, and negative-negative cortical support reductions, were simulated. A load of 700 N was applied to simulate a 70 kg elderly patient standing on one leg. The models were subjected to finite element analysis. The displacement and von Mises stress distributions were analyzed.

RESULTS

The positive-positive cortical support reduction pattern showed minimal stress and the negative-negative reduction pattern showed maximal stress on the intramedullary nail. The stress was mainly concentrated at the junction of the helical blade and the main nail and at the site of the lateral aspect of the insertion point of the nail in the great trochanter. The positive cortical support reduction patterns seemed to have smaller maximum displacements of the entire fragment-implant assembly and relative displacements between the head-neck and shaft fragments. Meanwhile, the negative reduction patterns seemed to have larger displacements.

CONCLUSION

The positive-positive support reduction pattern showed better mechanical stability for unstable pertrochanteric fractures. The negative-negative support reduction pattern was prone to fixation failure and should be avoided during an operation.

Trochanteric fixation nail advanced with helical blade and cement augmentation: early experience with a retrospective cohort

Intra-articular screw cut-out is a potential complication of intertrochanteric femur fracture fixation with a cephalomedullary nail. Cement augmentation of fixation in the proximal segment offers the prospect of increased stability and fewer complications, but clinical experience with non-resorbable cement is limited. To determine the handling properties and efficacy of this new technique, we performed a retrospective propensity-matched cohort of forty-four geriatric intertrochanteric femur fractures treated with a cephalomedullary nail with (n = 11) or without (n = 33) augmentation with non-resorbable cement injected into the proximal segment. In the patients treated with cement augmentation, at minimum 3-month follow-up, there were no instances of intra-articular cut-out, and no increase in re-operation compared to conventional fixation. Cement augmentation appears to be safe and effective in geriatric intertrochanteric femur fractures to mitigate risk of cut-out.

Cross-elements to enhance fixation in osteoporotic bone with application to proximal humeral locking plates: a biomechanical study

BACKGROUND

Proximal humeral fractures occur predominantly in elderly, osteoporotic individuals, especially women, with surgery performed in one-fifth. Proximal humeral locking plates are the gold standard operative treatment; however, complications are frequent, partially because of poor screw purchase in osteoporotic bone. A new method uses threaded posts through which threaded cross-elements orthogonally pass to create a 3-dimensional scaffold for bone engagement. We examined the pullout characteristics of the posts with (1 or 2) or without the cross-elements and tested 2 types of 3.5-mm cortical locking screws for comparison.

METHODS

Low-density closed-cell polyurethane foam served as a model osteoporotic bone substrate. Following implantation in the substrate, the devices were axially loaded by a mechanical test system. Quantities of interest included failure mode, peak load, displacement to peak load, initial stiffness, and work expended.

RESULTS

The post groups outperformed the 3.5-mm screw groups, as expected. Relative to posts with no cross-elements, 1 and 2 cross-elements increased the peak load by 29% and 87% and increased the work to peak load by 126% and 343%, respectively. After reaching peak load, 1 and 2 cross-elements increased the work-resistance to further displacement by 158% and 330%, respectively.

CONCLUSION

Cross-elements significantly increased the ability of the threaded posts to resist axial displacement from a model osteoporotic bone substrate. This suggests that posts, used in conjunction with cross-elements, have the potential to enhance the stability of proximal humeral locking plates in osteoporotic bone.

Enhancement of local bone formation on titanium implants in osteoporotic rats by biomimetic multilayered structures containing parathyroid hormone (PTH)-related protein

Osteoporosis is a severe health problem causing bone fragility and consequent fracture. Titanium (Ti) implants, used in patients with osteoporotic fractures, are prone to failure because of the decreased bone mass and strength. Therefore, it is of utmost importance to fabricate implants possessing osteogenic properties to improve implant osseointegration. To improve the long-term survival rate of Ti implants in osteoporotic patients, hyaluronic acid/ϵ-polylysine multilayers containing the parathyroid hormone (PTH)-related protein (PTHrP) were deposited on Ti implants by a layer-by-layer (LBL) electro assembly technique. The murine pre-osteoblast cell line MC3T3-E1, possessing a high potential of osteoblast differentiation, was used to evaluate the osteo-inductive effects of Ti-LBL-PTHrP in vitro. In addition, the performance of the Ti (Ti-LBL-PTHrP) implant was evaluated in vivo in a femoral intramedullary implantation in Sprague Dawley rats. The Ti-LBL-PTHrP implant regulated the release of the loaded PTHrP to increase bone formation in the early stage of implantation. The in vitro results revealed that cells on Ti-LBL-PTHrP did not show any evident proliferation, but a high level of alkaline phosphatase activity and osteoblast-related protein expression was found, compared to the uncoated Ti group (p < 0.05). In addition, in vivo micro-CT and histological analysis demonstrated that the Ti-LBL-PTHrP implants could significantly promote the formation and remodeling of new bone in osteoporotic rats at 14 d after implantation. Overall, this study established a profound and straightforward methodology for the manufacture of biofunctional Ti implants for the treatment of osteoporosis.

Proximal femur lag screw placement based on bone mineral density determined by quantitative computed tomography

Following internal fixations for intertrochanteric fractures in elderly patients, lag screws or screw blades frequently cut the femoral head, leading to surgical failure. The bone mineral density (BMD) at various parts of the proximal femur is significantly correlated with the holding force of the lag screw, which in turn is closely associated with the stability of the fixation. However, the appropriate placement of the lag screw has been controversial. As a novel detection method for BMD, quantitative computed tomography (QCT) may provide relatively accurate measurements of three-dimensional structures and may provide an easy way to determine the appropriate lag screw placement. A total of 50 elderly patients with intertrochanteric fractures were selected for the present study. The BMD of the proximal femur on the healthy side, including the femoral intertrochanter, neck and head, was measured using QCT. For testing, the femoral head was divided into medial, central and lateral sections. The BMD of the femoral head was determined to be the highest, while the BMD of the femoral neck was the lowest. In the femoral head, the central section had the highest BMD, while the lateral section had the lowest BMD. The present study used QCT to detect differences in the BMD at various regions of the proximal femur and provided a novel theoretical reference for the placement of lag screws. To obtain maximum holding power, the lag screw must be placed in the central section of the femoral head.

Hip Replacement as Alternative to Intramedullary Nail in Elderly Patients with Unstable Intertrochanteric Fracture: A Systematic Review and Meta-Analysis

Objective

To evaluate the efficacy and safety of hip replacement and intramedullary nails for treating unstable intertrochanteric fractures in elderly patients.

Methods

Randomized clinical trials (RCTs) to compare hip replacement with intramedullary nail in the management of elderly patients with unstable intertrochanteric femur fracture were retrieved from Cochrane Library (up to January 2018), CNKI (China National Knowledge Infrastructure), Wanfang Data, PubMed, and Embase. The methodological quality of the included trials was assessed using the Cochrane risk of bias assessment tool, and relevant data was extracted. Statistical analysis was performed by Revman 5.3. Where possible, we performed the limited pooling of data.

Results

Fourteen trials including a total of 1067 participants aged 65 and above were included for qualitative synthesis and meta‐analysis. The methodological quality of the included study was poor. The meta‐analysis indicated that the hip replacement group benefited more than the intramedullary nail group in terms of the bearing load time (WMD ‐14.61, 95% CI −21.51 to −7.7, P < 0.0001), mechanical complications (OR 0.34, 95% CI 0.21 to 0.57, P < 0.0001), and post‐operative complications (OR 0.46, 95% CI 0.22 to 0.93, P = 0.03). While the intramedullary nail was superior to arthroplasty regarding the intraoperative blood loss (WMD 58.36, 95% CI 30.77 to 85.94, P < 0.0001). However, there were no statistical significances in the length of surgery (WMD 5.27, 95% CI 4.23 to 14.77, P = 0.28), units of blood transfusion (WMD 0.34, 95% CI ‐0.16 to 0.85, P = 0.18), length of hospital stay (WMD ‐1.00, 95% CI ‐2.93 to 0.93, P = 0.31), Harris hip score (WMD 0.31, 95% CI ‐0.39 to 1.01, P = 0.38), and mortality (OR 1.24, 95% CI 0.12 to 13.10, P = 0.86).

Conclusions

This systematic review and meta‐analysis provided evidence for the efficacy and safety of hip replacement and intramedullary nail in treating unstable intertrochanteric fractures. However, the results should be interpreted cautiously because of methodological limitations and publication bias.

Factors that influence the complications and outcomes of femoral neck fractures treated by cannulated screw fixation

To investigate the influence of various factors on the two outcome parameters "procedure - specific complication" (femoral head necrosis, infection, nonunion, femoral neck shortening, screw loosening, implant penetration) and "functional outcome" in patients with displaced and undisplaced femoral neck fracture treated by cannulated screw fixation. All cases of a femoral neck fracture, operated by cannulated screw fixation, in the period from December 2014 to December 2017 were included. The observation period of the included patients was 12 months. Information on their outcome was collected after evaluation of current x-ray images and on request from the responsible further treatment physician. Continuous data were presented as mean value ± standard deviation, categorical data as absolute and relative frequency. The effect of potential factors on endpoints was estimated with a multivariable logistic regression analysis and 95% confidence intervals calculated. The null hypothesis Odds Ratio = 1 was checked by the Wald test. The likelihood ratio test was used to test for deviation from linearity. The mean age of the 56 included patients was 72 years (36 min, 96 max), 44.5% (n = 25) were male and 55.5% (n = 25) female. The femoral neck fractures were classified as follows: Garden I: 73%, Garden II: 16%, Garden III: 11%, Pauwels I: 73%, Pauwels II: 21%, Pauwels III: 5%, 31-B1: 73%, 31-B2: 27%, 31-B3: 0%. The factor patient age showed a statistically significant influence on the outcome parameter procedure-specific complication. None of the remaining factors examined showed a statistically significant influence on both outcome parameters procedure-specific complication and functional outcome. 69% of the patients from age 80 onwards suffered a procedure-specific complication. A rate of 41% procedure-specific complications as an outcome parameter in trauma surgery shows a necessity for improvement. The increasing risk of procedure-specific complications for patients with a femoral neck fracture treated by cannulated screw fixation is associated with rising patient age. A more stable head-perserving operative method or an endoprosthetic procedure should be considered in high-risk patients (≥80 y.o.).

Analysis of risk factors for loss of reduction after acromioclavicular joint dislocation treated with the suture-button

BACKGROUND

The most commonly reported complication after acromioclavicular (AC) joint dislocation treated with the Suture-button is loss of reduction. Loss of reduction is a major factor influencing the patient's joint function and subjective satisfaction. The objective of this study is to analyze the risk factors causing loss of reduction after AC joint dislocation treated with the Suture-button.

METHODS

One hundred and thirty patients with AC joint dislocation who were surgically treated the Suture-button in our hospital from February 2009 to February 2015, were recorded their age, sex, BMI, time from injury to surgery, Rockwood's classification, with or without osteoporosis, double or triple button technique, position of the clavicle tunnel, tunnel diameter, coracoid button position, alignment of the button, acromioclavicular ligament repair or not, different methods of postoperative limb immobilization, and so on. Mean comparisons or chi-square test was used for univariate analysis of the above factors, and then multivariate logistic regression analysis was performed to predict risk factors.

RESULTS

Reduction was lost in 23.1% of the patients. Univariate analysis showed that button alignment, double or triple button technique, coracoid button position, position of the clavicle tunnel, acromioclavicular ligament repair or not and osteoporosis had statistically significant association with loss of reduction for AC joint (P = 0.031, 0.034, 0.000, 0.042, 0.047 and 0.000 respectively). Multivariate logistic regression analysis demonstrated that osteoporosis (P = 0.003), position of the clavicle tunnel (P = 0.032) and coracoid button position (P < 0.001) were the risk factors that significantly associated with the loss of reduction after AC joint dislocation treated with the Suture-button.

CONCLUSIONS

Clavicle tunnel location using relative ratio method, accurate placement of button plate under coracoid process (inside or outside deviation <20°), various reinforcement operations for patients with osteoporosis are important factors in preventing loss of reduction.

Achievable accuracy of hip screw holding power estimation by insertion torque measurement

BACKGROUND

To ensure stability of proximal femoral fractures, the hip screw must firmly engage into the femoral head. Some studies suggested that screw holding power into trabecular bone could be evaluated, intraoperatively, through measurement of screw insertion torque. However, those studies used synthetic bone, instead of trabecular bone, as host material or they did not evaluate accuracy of predictions. We determined prediction accuracy, also assessing the impact of screw design and host material.

METHODS

We measured, under highly-repeatable experimental conditions, disregarding clinical procedure complexities, insertion torque and pullout strength of four screw designs, both in 120 synthetic and 80 trabecular bone specimens of variable density. For both host materials, we calculated the root-mean-square error and the mean-absolute-percentage error of predictions based on the best fitting model of torque-pullout data, in both single-screw and merged dataset.

FINDINGS

Predictions based on screw-specific regression models were the most accurate. Host material impacts on prediction accuracy: the replacement of synthetic with trabecular bone decreased both root-mean-square errors, from 0.54 ÷ 0.76 kN to 0.21 ÷ 0.40 kN, and mean-absolute-percentage errors, from 14 ÷ 21% to 10 ÷ 12%. However, holding power predicted on low insertion torque remained inaccurate, with errors up to 40% for torques below 1 Nm.

INTERPRETATION

In poor-quality trabecular bone, tissue inhomogeneities likely affect pullout strength and insertion torque to different extents, limiting the predictive power of the latter. This bias decreases when the screw engages good-quality bone. Under this condition, predictions become more accurate although this result must be confirmed by close in-vitro simulation of the clinical procedure.

Rewriting the tip apex distance for the proximal femoral nail anti-rotation

INTRODUCTION

The proximal femur nail anti-rotation (PFNA-II) (Synthes GmbH, Oberdorf, Switzerland) is the most commonly used implant for intramedullary nailing of unstable intertrochanteric fractures in our centre. However, mechanical failure of the bone with respect to the implant is a cause of concern due to its significant morbidity especially in the elderly. To date, factors for fixation failures are not well defined in the literature. This study aims to evaluate the factors that predispose to cut out of the PFNA implant and to provide a guide for surgical fixation.

PATIENTS AND METHODS

This study was a retrospective analysis of 340 patients who underwent PFNA-II insertion from 2011 to 2013 in our centre. Intraoperative image intensifier images were used for calculation of tip apex distance, neck shaft angles, determination of Cleveland zones. Demographic data was collected on patients age and gender. The fractures were classified based on AO-OTA classification (Marsh et al., 2007) [1]. Patients were followed up for a minimum of 4 months and union of the fracture or until a complication occurred. Risk ratio for cut out was also compared with each statistically significant variable to determine the cut-off point.

RESULTS

The incidence of cut out was 6.7% Tip apex distance, neck shaft angles and female gender were statistically significant for cut out. The study found that tip apex distance beyond 27mm increased the risk of cut out. Neck shaft angles less than 128° also increased the risk of cut out. Posterior and superior blade position in the femoral head and AO 31A3 fractures trended towards significance for cut out but were not statistically significant.

CONCLUSION

To avoid cut out, one should aim for a tip apex distance of not more than 27mm and preserve a neck shaft angle of more than 128°. Risk stratification of the patient allows the surgeon to take greater caution in the post-operative period to detect early cut out.

The treatment strategies of intertrochanteric fractures nonunion: An experience of 23 nonunion patients

BACKGROUND

Intertrochanteric femoral fractures are common, but the nonunion of intertrochanteric fractures is not. The purpose of this study was to divide intertrochanteric fracture nonunion into different types and give corresponding treatment strategies.

METHODS

We retrospectively evaluated 23 patients with intertrochanteric fracture nonunion. The patients were divided into five groups and each group was treated with a different strategy. All patients had staged clinical and radiographic follow-ups and the mean follow-up was 16.0±4.6months.

RESULTS

Except for the patients treated with total hip arthroplasty, all patients achieved fracture union. The mean union time was 4.7±1.2months. The Harris hip function score differed significantly from preoperative (28.9±6.8) to postoperative (83.8±6.3; p<0.05). For the three patients who were classified as type III, the femoral neck shaft angle was corrected to a significant degree, from 97.3±6.4 to 127.3±2.5 (p<0.05). For the four patients who were classified as type V, the mean time from debridement to re-internal fixation was 3.7±1.5months.

CONCLUSIONS

There are several factors associated with the failure of intertrochanteric fracture treatments. We need to analyze the causes of fracture treatment failure carefully. Based on our five classifications and corresponding treatment strategies, the radiographic and functional treatment outcomes were satisfactory. Future larger comparative studies are needed to confirm our results.

Plate fixation of periprosthetic femur fractures: What happens to the cement mantle?

Osteosynthesis of periprosthetic femur fractures by screw fixation around the implanted prosthetic stem is currently regarded as the biomechanically superior option compared with cerclage. The aim of this biomechanical study was damage analysis of the cement mantle after revision screw insertion. A prosthetic stem (Bicontact) was implanted in 20 cadaveric femora in cemented technique. A locking compression plate (Synthes) was then applied to the lateral femur at the level of the prosthetic stem. The method of plate fixation to the femur was assigned randomly to three groups: bicortical non-locking screws, monocortical locking screws, and bicortical locking screws. This was followed by applying a fluctuating axial load (2100 N, 0.5 Hz) for 20,000 cycles. After testing, macroscopic and microscopic evaluations of the cement mantle were conducted. Cracks formed in the cement mantle in 14% of the 80 screw holes. The type of screw (bicortical or monocortical; locking or non-locking) had no significant effect on the number of cracks (p = 0.52). The relationship between manifestation of crack damage and cement mantle thickness was not significant (p = 0.36), whereas the relationship between crack formation and screw position was significant (p = 0.019). Those screws whose circumference was only partially within the cement mantle yielded a significantly lower number of cracks compared with screws positioned completely within the cement mantle or even touching the prosthetic stem. In order to reduce the incidence of crack formation in the cement mantle during plate osteosynthesis of periprosthetic femur fractures, the screws should not be either placed within the cement mantle or make direct contact with the stem.

Failure of fracture fixation in osteoporotic bone

This manuscript will provide an overview of how the age and osteoporosis related changes in mechanical properties of bone affect the stability of osteosynthesis constructs, both from a mechanical as well as from a clinical perspective. The manuscript will also address some of the principles of fracture fixation for osteoporotic fractures and discuss applications of osteoporotic fracture fixation at sites typically affected by fragility fractures, namely the distal radius, the proximal humerus, the femur and the spine. The primary aim of operative treatment in elderly individuals is the avoidance of immobilization of the patient. In selected cases conservative treatment might be required. Generally, choice of treatment should be individualized and based on the evaluation of patient-specific, fracture-specific and surgeon-specific aspects. The orthopaedic surgeon plays an essential role in enabling functional recovery by providing good surgery but a multidisciplinary approach is essential in order to support the patient to regain his/her quality of life after fragility fracture. Overall, the therapy of fractures in osteoporotic bone in the elderly requires a multidisciplinary therapeutic acute care concept including treatment of co-morbidities and correct choice of timing, and technique of the operative intervention.

When is the stability of a fracture fixation limited by osteoporotic bone?

This article is concerned with the search for threshold values for bone quality beyond which the risk of fixation failure increased. For trochanteric fractures we recognized a BMD lower than 250mg/cm(3) as an additional risk for cut out. For medial femoral neck fractures since joint replacement surgery is available and produces excellent functional results, we see no indication for further differentiation or analysis of bone quality in relation to fracture fixation. In the area of osteoporotic vertebral body fractures, there are many experimental studies that try to identify BMD limits of screw fixation in the cancellous bone on the basis of QCT analysis. However, these values have not yet been introduced for application in clinical practice. In case of indication for surgical fixation, we favor minimally invasive, bisegmental, fourfold dorsal instrumentation with screw-augmentation for a T-value less than -2.0 SD (DXA analysis, total hip or total lumbar spine). For proximal humerus fractures, BMD value of 95mg/cm(3) could be seen as a threshold value below which the risk of failure rises markedly. In relation to osteoporotic distal radius fractures, based on our clinical experience and scientific analyses there are virtually no restrictions as far as bone quality is concerned on the application of palmar locking implants in the surgical management of distal radius fractures. Optimization of preoperative diagnostics might help to revise the treatment algorithm to take bone density into account, thus reducing the risk of failure and, at the same time, acquiring additional data for future reference.

The long and short of cephalomedullary nails in the treatment of osteoporotic pertrochanteric fracture

INTRODUCTION

Pertrochanteric fractures after low-energy trauma are common among osteoporotic patients. Although the use of intramedullary devices to treat such fractures is becoming increasingly popular, there is a paucity of data comparing the outcomes of the use of short cephalomedullary nails (SCN) with the use of long cephalomedullary nails (LCN). This study aimed to compare the outcomes of treatment using LCN with treatment using SCN for patients with osteoporotic pertrochanteric fractures.

METHODS

A retrospective review of 64 patients with osteoporotic pertrochanteric fractures who were treated with either LCN or SCN and had a minimum follow-up of one year was performed. Primary outcome measures include complications, revision surgeries and union rates. Secondary outcome measures include duration of surgery, estimated blood loss, length of hospital stay, and ambulatory and mortality status at one year.

RESULTS

There was no significant difference in the clinical and functional outcomes of the patients who were treated with LCN and those who were treated with SCN. However, there was a higher incidence of heterotopic ossification in the latter group, and a slightly greater average estimated blood loss and duration of surgery in the former group. Patients treated with LCN tended to be more osteoporotic.

CONCLUSION

Our study found no significant difference in terms of complications, revision surgeries, union rates and ambulatory status between the patients who were treated with LCN and those who were treated with SCN. Both LCN and SCN provided safe and reliable outcomes in the treatment of osteoporotic pertrochanteric fractures.

The effect of local bone density on mechanical failure after internal fixation of pertrochanteric fractures

INTRODUCTION

The aim of this prospective study was to investigate the effect of local hip bone density on mechanical failure after fixation of pertrochanteric fractures and to establish possible risk factors for the failures.

MATERIALS AND METHODS

A total of 136 consecutive patients presenting a closed unilateral pertrochanteric fracture were enrolled. The patients were treated with a sliding hip screw or an intramedullary nail. Dual energy X-ray absorptiometry measurements for bone density of the contralateral hip were made within 4 weeks postoperatively. Follow-up evaluations on the standard radiographs were documented for any mechanical failure including loss of reduction, screw or blade cut-out, lateral migration of the screw or blade, and implant breakage. Secondary outcomes were also recorded including patient characteristics and fixation construct variables as possible predictors for mechanical failure.

RESULTS

At a minimum of 2 years of follow-up, 38 patients were reported with mechanical failure at an estimated risk of 27.9 %. The local bone density measurements for the study population showed no difference between patients with (0.710 g/cm(2)) and without (0.726 g/cm(2)) mechanical failure (P = 0.180). We also observed no significant correlation between local bone density and failure in patients with good fracture reduction (P = 0.862). The multivariate regression analysis identified fracture type (P < 0.001) and quality of fracture reduction (P < 0.001) as being independent predictors for mechanical failure, whereas local bone density was not (P = 0.658).

CONCLUSIONS

Local hip bone density does not appear to have a significant influence on mechanical failure after internal fixation of pertrochanteric fractures. Stable fractures and fractures with good reduction are expected to obtain satisfactory outcomes.

[Biaxial reconstruction nail for pertrochanteric femoral fractures. Osteosynthesis]

BACKGROUND

The steady rise in life expectancy of our population leads to an exponential increase in proximal femoral fractures. The growing increase of comorbidities in these patients requires continuous development of modern implant systems for internal fixation of proximal femoral fractures.

MATERIALS AND METHODS

In this study we enrolled 116 patients with pertrochanteric femoral fractures who were treated with a proximal femoral nail (Targon PF, Aesculap) over a period of 1 year. The indications for this implant system were set at unstable fracture types. Data of the operative and postoperative course were collected prospectively.

RESULTS

The average age of the 116 predominantly female subjects was 77±14 years and the most commonly observed fracture subtype was 31-A1.2. The follow-up rate was 55 %. We observed a decrease in the postoperative modified Harris hip score of 22.7 %. The 1-year mortality was 21.6 %.

CONCLUSIONS

The results of this study showed a low rate of perioperative complications and implant loss anda decline in patient mobility was typically observed within 1 year.

Biomechanical evaluation of two innovative locking implants for comminuted olecranon fractures under high-cycle loading conditions

INTRODUCTION

The relatively high complication rate after fixation of olecranon fractures has led to an increasing application of anatomically pre-contoured locking plate systems. The purpose of the present study was to conduct a biomechanical comparison of olecranon osteosyntheses by applying the Olecranon VA-LCP and the 3.5mm LCP Hook Plate (LCP, locking compression plate) to an unstable fracture model under high-cycle loading conditions.

METHODS

After creating an unstable fracture (Schatzker type B), osteosynthesis was performed on eight pairs of fresh-frozen cadaveric ulnae by application of either the Olecranon VA-LCP (Synthes, Solothurn, Switzerland) or the 3.5mm LCP Hook Plate (Synthes, Solothurn, Switzerland). Loading (50,000 alternating loads, cyclic and sinusoidal 10-300 N) was conducted by application of tensile load with the elbow in 90° flexion to simulate the tensile strength of the triceps brachii. For statistical analysis, angular displacement in the region of the humeral trochlea was taken as a measure of olecranon dislocation.

RESULTS

In Group 1 (Olecranon VA-LCP), a median angular displacement of 0.36° (minimum 0.10°; maximum 0.80°) was observed after 500 alternating loads. In Group 2 (3.5-mm LCP Hook Plate), the medial displacement was 0.80° (minimum 0.13°; maximum 2.72°). The difference was nonsignificant (p = 0.128). The mean value for angular displacement in Group 1 after 50,000 cycles was 0.80° (minimum 0.31°; maximum 1.99°), whereas in Group 2 a mean angular displacement of 2.02° (minimum 0.71°; maximum 6.40°) was recorded. The difference was statistically significant (p = 0.017). In Group 2, implant failure in the form of proximal plate pullout occurred in one construct after 756 cycles.

CONCLUSION

A significantly higher biomechanical stability can be achieved in the fixation of unstable olecranon fractures by application of the Olecranon VA-LCP rather than the 3.5mm LCP Hook Plate.

Sliding of the load carrier in third-generation intramedullary nails for proximal femur fractures: an in vitro mechanical comparison study

Dynamic osteosynthesis of proximal femur fractures facilitates compression at the fracture site through distal glide of the femoral head load carrier in the intramedullary nail. Modern implants are currently designed according to diverse gliding principles. The aim of this study was to compare the sliding mechanisms of different types of nails. As in other similar mechanical studies the load patterns occurring around the femoral head load carrier and the intramedullary nail under full load were simulated for three different types of intramedullary nail - PFNA, Targon PFT and Trigen Intertan. The load necessary to trigger distal displacement of the femoral head implant in the nail was determined. The lengths of the load carriers were varied. For the three lengths of load carrier, mechanical testing showed that the Targon PFT started to slide at a significantly lower load compared to the other two implants. Comparison of the PFNA and Trigen Intertan in terms of load to dynamization for 77 mm carriers revealed a significantly lower load for the PFNA. Slide efficacy for the PFNA and the Trigen Intertan was found to improve as the length of the blade/screw was shortened. The dynamization properties of the Targon PFT with its cylindrical sliding mechanism, similar to the DHS, were far better compared to the PFNA and the Trigen Intertan that have more complex sliding actions. Since theoretical considerations indicate that a less efficient gliding action leads to a higher complication rate, implants of the next generation should be optimized in this regard.