Compression Hip Screw Research Articles

Oncological and functional outcomes of pathological fractures of lower extremities in patients with malignant bone tumors.

As managing pathological fractures of the extremities can be difficult, the present study aimed to present a treatment algorithm for lower extremity bone malignancies. A total of 38 patients with impending and pathological fractures were treated at the Department of Orthopedic Surgery in Kindai University Hospital. Age, sex, fracture site, type of primary malignancy, number of metastases, pre-fracture Eastern Cooperative Oncology Group performance status (ECOG-PS) score, adjuvant therapy, treatment modality, operative time, blood loss, postoperative complications, Musculoskeletal Tumor Society (MSTS) score, outcomes, follow-up period and the MSTS scores and ECOG-PS were compared in cases of primary malignant tumors and those cases of metastatic malignant tumors were retrospectively surveyed. Post-treatment MSTS scores in cases of impending and pathological fractures were compared between intramedullary nail fixation and non-intramedullary nail fixation procedures. Disease sites included the sub-trochanteric femur in 10 patients, trochanteric femur in 8, femoral diaphysis in 7, femoral neck in 5, bilateral trochanteric femur in 3, proximal tibia in 3 and distal femur in 2 patients. A total of 10 patients had metastases between 3-20 sites. The median pre-fracture ECOG-PS score was 1. Adjuvant radiotherapy was administered to 5, chemotherapy to 8 and radiotherapy with chemotherapy to 10 patients. Surgical procedures included intramedullary nails in 18 patients, tumor arthroplasty in 4, plate fixation in 3, artificial head replacement in three, compression hip screw (CHS) in 3, conservative treatment in 2, bilateral intramedullary nail fixation in 2 and artificial bone stem with combined intramedullary nail and plate fixation, right-sided artificial head replacement and left-sided CHS in 1 patient each. The MSTS score was 19.9±8.95 for intramedullary nail fixation and 24.3±7.45 for other procedures, with a negative association between the MSTS score and pre-fracture ECOG-PS. The median follow-up period was 8 months. The outcomes were as follows: Alive with disease, 23 patients; continued disease-free, 1 patient; and dead due to disease, 14 patients. The 1-year postoperative overall survival rate was 60.5%. Moreover, the group with metastatic malignant tumors, which had significantly worse ECOG-PS, had significantly lower MSTS scores than the group with primary malignant tumors. The authors' treatment algorithm for malignant bone tumors of the lower extremity was shown to be useful.

Treatment algorithm for metastatic malignancies in the lower extremities.

A high prevalence of proximal femoral metastases persists in patients with cancer, particularly regarding lower extremity fractures. This study offers a detailed analysis of clinical characteristics of patients undergoing surgical treatment for pathological or impending fractures, enhancing treatment strategies for metastatic malignancies. A total of thirty patients who underwent treatment of impending and pathological fractures at Kindai University Hospital (Osakasayama, Japan) were included. The retrospective study comprised parameters including age, sex, fracture site, type of primary malignancy, number of metastases, pre-fracture Eastern Cooperative Oncology Group performance status (ECOG-PS) score, adjuvant therapy, treatment modality, operative time, blood loss, postoperative complications, Musculoskeletal Tumor Society (MSTS) score, outcome and follow-up period. Post-treatment MSTS scores were compared in cases of impending and pathological fractures, and between intramedullary nailing and other surgical procedures. In addition, one-year postoperative survival rates were calculated. Furthermore, operative time, blood loss and survival rates were compared between impending and pathological fractures. The participants' median age was 70.5 years, with disease sites primarily in the subtrochanteric femur, trochanteric femur, femoral diaphysis, femoral neck and other locations. Pathologies included multiple myeloma and unknown primary, lung, breast, kidney, liver, gastric, esophageal and uterine cancers. The median ECOG-PS score pre-fracture was 2. Treatment approaches involved radiotherapy, chemotherapy and a combination of both. Surgical interventions included intramedullary nailing (16 cases), endoprosthesis (1 case), bipolar head replacement (3 cases) and compression hip screw (3 cases), among others. A negative correlation (R=-0.63) existed between MSTS and pre-fracture ECOG-PS scores. The operative time was significantly shorter in impending than in pathological fractures, with impending fractures showing significantly lower blood loss. The treatment algorithm for malignant bone tumors of the lower extremity provided in the present study was efficient, potentially optimizing treatment strategies for such cases, and contributing to improved patient care and outcomes in oncology and orthopedic surgery.

Early Failure of Locking Compression Plates in Pediatric Proximal Femoral Fracture

Background: Although proximal femoral locking compression plates (PF-LCP) have been used with increasing frequency in the fixation of proximal femoral fractures in the pediatric population, there is a lack of literature regarding their use. The purpose of this study was to examine the failure rates of PF-LCP fixation in comparison to other accepted fixation methods within a pediatric population.Methods: Retrospective review identified consecutive children treated for proximal femoral fractures from September 2008 to February 2019, who had a minimum follow-up of 12 weeks. Patient charts and radiographs were reviewed, and demographic information was compiled. In the case of failures, timing and method of failure were documented.Results: Sixty-four proximal femoral fractures (61 children) were studied. The average age at the time of presentation was 10.4 years. Twenty-six fractures were treated with PF-LCPs and 38 with other fixation methods (compression hip screws, rigid locked intramedullary nailing, cannulated screws, or a combination of hip screw side plate and intramedullary nailing). Failure occurred in four of the 26 fractures treated with locking compression plating (15.4%) compared to none of the 38 treated with other fixation types (p<0.05).Conclusions: This study demonstrates a higher rate of failure in proximal femoral fractures, particularly basicervical and transcervical femoral neck fractures, treated with locking compression plates (12.9%) compared to 0% other fixation methods (no failures). As a result of this study, we no longer use locked plating systems for pediatric femoral neck fractures at our institution.Level of Evidence: Level III Key Concepts•Proximal femoral fractures account for less than 1% of all fractures in children.•Locking compression plates are being more frequently used in pediatric proximal femoral fractures.•Outcome studies are limited because of the low incidence of these fractures and relative recent introduction of this fixation method.•Proximal femoral compression locking plates had a higher rate of early mechanical failure than other fixation modalities in this study.•The increased risk of failure with proximal femoral compression locking plates should be considered before opting for these implants.

Occult proximal femoral fracture with radiating leg pain masquerading as sciatica: a case report

BackgroundOccult proximal femoral fractures do not appear as fracture lines in radiographs, causing misdiagnosis and delayed diagnosis unless additional imaging studies, such as computed tomography or magnetic resonance imaging, are performed. Here, we present a 51-year-old male with an occult proximal femoral fracture who experienced radiating unilateral leg pain that took 3 months to be diagnosed because his symptoms mimicked lumbar spine disease.Case presentationA 51-year-old Japanese male experienced persistent lower back and left thigh pain after falling off a bicycle, and was referred to our hospital 3 months thereafter. Whole-spine computed tomography and magnetic resonance imaging revealed minute ossification of the ligamentum flavum at T5/6 without spinal nerve compression, but this did not explain his leg pain. Additional magnetic resonance imaging of the hip joint revealed a fresh left proximal femoral fracture without displacement. He underwent surgery for in situ fixation using a compression hip screw. Post-surgical pain relief was immediate.ConclusionsMisdiagnosis of occult femoral fractures as lumbar spinal disease may occur if distally radiating referred pain is present. Hip joint disease should be considered as a differential diagnosis in cases of sciatica-like pain with an unknown spinal origin and no specific findings on spinal computed tomography or magnetic resonance imaging accounting for the leg pain, especially following trauma.

Conversion total hip arthroplasty after previous intertrochanteric hip fractures: a review of the epidemiology, technical issues, and outcomes

Conversion total hip arthroplasty (THA) after previous intertrochanteric (IT) hip fracture is a unique operation that is different from the routine primary total hip arthroplasty (THA) done for osteoarthritis or femoral head necrosis. Conversion THAs are similar to revision THAs with regard to complexity, technical challenges, implant costs, and perioperative complications. A literature review was performed with specific focus on the surgical techniques, patient outcomes, and financial burdens of conversion THAs after IT fracture treatment with either a sliding compression hip screw with side plate (SSP), or a cephalomedullary nail (CMN). The reported data demonstrated similar technical challenges regardless of the method of the index treatment of the IT fracture. The surgeon must plan and be prepared for more difficult and extensile exposure, available instruments for the hardware removal, altered proximal femoral geometry, and available implant inventory for the reconstruction. The outcomes are consistent with higher rates of instability and infection in the conversion THAs compared with primary THAs. There is no significant difference in the clinical outcomes of conversion THAs following either SSP or CMN. Overall, conversion THAs pose greater technical challenges. The clinical outcomes of conversion THAs remain inferior to the primary THAs. The complications and patient functional outcomes are similar to those following revision THAs.

Treatment of Basicervical Femoral Fracture With Retractable Talon Hip Compression Screw.

BackgroundBasicervical femoral fractures (BFFs) are rare and biomechanically unstable. The goal of this study was to evaluate the effectiveness of the Talon™ DistalFix™ (Orthopedic Designs North America, Inc., Tampa, FL, USA) nail for the treatment of BFFs with a novel design.MethodologyIn this retrospective study, 25 patients with BFFs were analyzed between January 2016 and March 2020 at our institute. All patients were treated with the Talon™ DistalFix™ nail. Patients over the age of 60 years with basicervical fractures caused by low-energy trauma were included in this study. For inclusion into the study, the minimum follow-up time had to be longer than six months. The postoperative radiographic bone union, operative time, tip-apex distance (TAD), sliding distance of the lag screw, quality of fracture reduction, and major complications such as cut-out, non-union of the fracture, femoral head collapse, and cut-through were recorded. The Harris Hip Score was used to evaluate hip function at the end of the follow-up period.ResultsThe mean follow-up period was 22 months (range, 16-28 months), and the mean age was 77.8 years (range, 61-91 years). The average sliding distance of the lag screw was 5.7 mm (range, 0.2-13.1 mm). The mean TAD of immediate postoperative view was 20.8 mm (range, 18.7-23.7 mm), and the TAD was <25 mm in all cases. Radiographic union was confirmed in most cases, and the average time for radiographic union was 18.8 weeks (range, 12-25 weeks). Most fractures (90.5%) had healed with no postoperative mechanical complications (cut-out, cut-thorough, or lateral wall fracture) at the final follow-up, except for two patients. One of the two patients had no evidence of union at six months, and mild varus reduction was observed in the other patient who had shortening of >10 mm.ConclusionsAccording to the clinical and radiological findings of this study, treatment with the Talon™ DistalFix™ nail showed satisfactory results. Hence, it can be a suitable option in the treatment of BFFs.

Examination of Treatment Results of Compression Hip Screw (CHS) and Twin Hook (TH) for Trochanteric and Basicervical Fractures of the Femur

Examination of Treatment Results of Compression Hip Screw (CHS) and Twin Hook (TH) for Trochanteric and Basicervical Fractures of the Femur

A Finite Element Analysis of Transtrochanteric Curved Varus Osteotomy Combined with Compression Hip Screw System

Background: Complications such as Nonunion, Metal failure and Periprosthetic fracture were found after the TCVO surgery accounting for the mechanical reasons mainly, moreover. There was no any research for simulating TCVO model by using the finite element analysis from the literature. Methods: A TCVO model with 25° fixed with compression hip screw system, which assigned an isotropic heterogeneous material property for the femur was estimated and simulated initial post-operative stage and bone-healing stage, in which the mechanical parameters were compared. Results: (1) The Max displacement in non-friction condition was 9.695 mm. And a strong decrease with the Max displacement of 3.456 mm in condition of bonding for the interfaces. (2) The concentration of von Mises stress on the interfaces were present at the area of lag tunnel with the Max values: 122.0MPa in shaft and 84.20MPa in head, comparing the bone-healing stage, the concentration of von Mises stress in the infero-medial area of contact of the shaft with the Max values: 80.95MPa. (3) The concentration of von Mises stress was both displaced in the junction of osteotomy for the CHS system with the Max von Mises stress values: 1765MPa and 334MPa in two conditions. Conclusions: It was conformed that there was higher instability and fracture risk in the initial post-operative period with more displacement and higher stress in the concentrated point, it was indicated that the load-constrained activities and strong fixation were benefit to decrease the complication and improve the success rate for clinical practice.

Salvage of cephalomedullary nail cutout with the variable angle proximal femoral plate

IntroductionExcellent results have been published in the treatment of the trochanteric fractures in the elderly with cephalomedullary nails or compression hip screws but not free of complications. The perforation of the lag screw through the superior cortex of femoral neck or head followed by rotation and varus collapse of the head-neck fragment, also known as cut-out, is one of them. Probably total hip arthroplasty is the most common solution, but there is no systematic technique for treatment. The objective of this study is to evaluate the results obtained in the treatment of this complication using a variable angle femoral plate. Material and methodsThis retrospective study concerns patients over 65 years with peritrochanteric fractures treated with cephalomedullary nail with cut-out failure solved by re-osteosyntesis with variable angle femoral plate between 1st January 2000 and 31 st December 2017. The series includes 29 patients, 26 women and 3 men with average age 87,3. Patients were followed up clinically and radiologically at regular intervals until fracture consolidation at least 9 months. ResultsNo patients died at the first 9 months after surgery. Fracture mean consolidation has occurred in all patients in 14th weeks (6-20). Operative time was 93,2 minutes (62-129) including removal of nail. No intraoperative complications were observed. Five patients experienced medical complications and two had a superficial wound infection. The mean tip-apex distance (TAD) was 5mm (2-7mm). The neck-shaft angle was 127 degrees. The mean valgization achieved was 32 degrees (15-40). Only one patient needed a second revision surgery due to aseptic hip joint subluxation after 8 weeks of the surgery solved with total hip arthroplasty. ConclusionsThe use of variable angle femoral plate in the cut-out treatment is an attractive option which allows the valgization of the fracture to virtually physiological limits and the placement of the cephalic screw in the most sutiable position with good outcomes and few complications.

Clinical Results of Dual SC Screw: A Mini-Sliding Hip Screw with an Anti-rotating Screw for Femoral Neck Fractures.

BackgroudDual SC screw (DSCS) is a unique concept internal fixation device consisting of a sliding screw and barrel assembly that enables compression force to be applied to the femoral neck fracture side. There are two types of barrels: a thread barrel and a plate barrel that has a one-holed side plate to prevent varus deformity. We report clinical results of the application of a DSCS with combined use of a thread barrel screw as an anti-rotational screw and a plate barrel screw as a compression hip screw.MethodsWe used DSCS for femoral neck fractures in 196 hip joints of 190 patients between November 2005 and June 2017. Among them, 70 hips in 66 patients (13 men and 53 women; mean age, 73.2 years) were followed up for at least 24 months. There were 53 nondisplaced fractures (Garden's classification stage 1 or 2) and 17 displaced fractures (stage 3 or 4). We evaluated the postoperative walking ability of the patients who were followed up for at least 24 months and examined details of all complications.ResultsThe mean follow-up period was 37.4 months (range, 24–144 months). Forty-two (64%) out of the 66 patients who were followed up for at least 2 years were able to walk independently with or without a cane. The incidence of complications was 11.5% in nondisplaced fractures and 17.5% in displaced fractures, and arthroplasty was required in 5.8% and 5.0%, respectively. The most frequent complication was secondary displacement including cutout and shortening of the femoral neck, but no implants showed varus displacement.ConclusionsThe application of DSCS for the treatment of femoral neck fractures had satisfactory results. The complication rate was low, and there was no postoperative varus displacement of DSCS in either displaced or nondisplaced fractures. We suggest DSCS is a reliable option for both displaced and nondisplaced femoral neck fractures.

Preoperative Mild Pericardial Effusion Is Associated With Perioperative Complications In Elderly Patients Following Hip Fracture Surgery

Background: The prevalence and prognostic value of mild pericardial effusion (MPE) has not been examined in patients undergoing non-cardiac surgery. Our study aimed to assess the frequency and prognostic value of MPE in elderly patients undergoing surgery for hip fracture. Methods: This is a single center, and retrospective study including elderly patients who underwent hip fracture surgery. The medical records of all patients, aged ≥65 years with femoral neck, intertrochanteric or subtrochanteric hip fracture undergoing surgery (intramedullary hip screw, sliding compression hip screw, hemiarthroplasty, or total hip arthroplasty) from June 2014 to June 2019 were analyzed. Patients with of multiple trauma and accidents were excluded. The MPE was defined as the presence of <10 mm pericardial effusion. The primary outcomes of the study were perioperative adverse medical events and length of stay in hospital. Results: A total of 462 patients (mean age 75.2 ± 11.7 years, and 53.5% female) were enrolled. MPE was detected in 72 patients (15.6%), and 62 patients (13.4%) experienced perioperative adverse medical events. Patients with MPE were older, had higher prevalence of diabetes, coronary artery disease, and heart failure, and had longer length of stay compared to patients without MPE. Univariate analysis showed a significant association between age, diabetes, coronary artery disease, American Society of Anesthesiologists status, MPE, and perioperative adverse events. After adjustment for age, demographics, and medical history, the presence of MPE remained as significant variable associated with perioperative complications (OR: 2.543, 95% CI: 1.173–3.469, p = 0.003). Conclusion: Our study is the first to demonstrate that the presence of MPE is associated with perioperative adverse events in elderly patients undergoing hip fracture surgery.

Strength⁻Durability Correlation of Osteosynthesis Devices Made by 3D Layer Manufacturing.

To develop orthopedic implants that are optimized for each patient’s needs or skeletal structure (custom-made implants), evaluations of the bending strength, bending stiffness, and durability of various types of conventional osteosynthesis devices have become important. Four-point bending tests and compression bending tests of osteosynthesis devices (bone plates, intramedullary nail rods, spinal rods, compression hip screws (CHSs), short femoral nails, and metaphyseal plates) were carried out to measure their bending stiffness, bending strength, and durability. The bending stiffness of bone plates, intramedullary nails, spinal rods, CHSs, short femoral nails, and metaphyseal plates increased with increasing bending strength. The durability limit of various types of osteosynthesis devices linearly increased with increasing bending strength. The relationship (durability limit at 106 cycles) = 0.67 × (bending strength) (N·m) (R2 = 0.85) was obtained by regression. The relationship for the highly biocompatible Ti-15Zr-4Nb-4Ta alloy was also linear. The mechanical strength and ductility of specimens that were cut from various osteosynthesis devices were excellent and their microstructures consisted of fine structures, which were considered to be related to the excellent durability. These results are expected to be useful for the development of implants suitable for the skeletal structure of patients using three-dimensional (3D) layer manufacturing technologies.

Biomechanical Analysis of Fixation Devices for Basicervical Femoral Neck Fractures.

Basicervical femoral neck fractures are challenging fractures in geriatric populations. The goal of this study was to determine whether compression hip screw (CHS) constructs are superior to cephalomedullary constructs for the treatment of basicervical femoral neck fractures. Thirty cadaver femurs were osteotomized and received a CHS with derotation screw, a long cephalomedullary nail (long Gamma nail), or a short cephalomedullary nail (short Gamma nail). All constructs were loaded dynamically in compression until dynamic failure. All failed CHS constructs demonstrated superior femoral head cutout. In the long Gamma nail and short Gamma nail groups, constructs failed by nail cutout through the medial wall of the trochanter or rotationally. Normalized fluoroscopic distance was found to increase markedly with an increasing cycle count when considering all treatment groups. Given our results and those of previous studies, we could not determine superiority of one implant and recommend that surgeons select fixation constructs based on the individual patient's anatomy and the surgeon's comfort with the implant.

Outcomes of Internal Fixation with Compression Hip Screws in Lateral Decubitus Position for Treatment of Femoral Intertrochanteric Fractures.

PurposeInternal fixation using compression hip screws (CHS) and traction tables placing patients in the supine position is a gold standard option for treating intertrochanteric fractures; however, at our institution, we approach this treatment with patients in a lateral decubitus position. Here, the results of 100 consecutive elderly (i.e., ≥45 years of age) patients who underwent internal fixation with CHS in lateral decubitus position are analyzed.Materials and MethodsBetween March 2009 and May 2011, 100 consecutive elderly patients who underwent internal fixation with CHS for femoral intertrochanteric fracture were retrospectively reviewed. Clinical outcomes (i.e., Koval score, Harris hip score [HHS]) and radiographic outcomes (i.e., bone union time, amount of sliding of lag screw, tip-apex distance [TAD]) were evaluated.ResultsClinical assessments revealed that the average postoperative Koval score decreased from 1.4 to 2.6 (range, 0–5; P<0.05); HHS was 85 (range, 72–90); and mean bone union time was 5.0 (range, 2.0–8.2) months. Radiographic assessments revealed that anteroposterior average TAD was 6.95 (range, 1.27–14.63) mm; lateral average TAD was 7.26 (range, 1.20–18.43) mm; total average TAD was 14.21 (range, 2.47–28.66) mm; average lag screw sliding was 4.63 (range, 0–44.81) mm; and average angulation was varus 0.72°(range, −7.6°−12.7°). There were no cases of screw tip migration or nonunion, however, there were four cases of excessive screw sliding and six cases of varus angulation at more than 5°ConclusionCHS fixation in lateral decubitus position provides favorable clinical and radiological outcomes. This technique is advisable for regular CHS fixation of intertrochanteric fractures.

Minimal Invasive Dynamic Hip Screw Fixation for Intertrochanteric Fractures of Femur

INTRODUCTION: Good results have been achieved consistently with compression hip screw fixation for stable intertrochanteric femur fractures by conventional method. Thus, this present study was conducted to find out the outcomes for such hip fracture fixation with minimal invasive technique. MATERIALS AND METHOD: This retrospective study was carried out by collecting the records of 66 adult patients with stable intertrochanteric femur fracture managed by Dynamic Hip Screw (DHS) fixation with minimal invasive technique under Spinal Anaesthesia and Epidural Analgesia in Universal College of Medical Sciences and Teaching Hospital (UCMSTH) over a period of 3 years. The patients were in follow up visits for 1 year postoperatively. Operating time, blood loss, decrease in haemoglobin level, analgesic demand, length of hospital stay, fracture union time, early and delayed complications and functional outcome were recorded. RESULTS: This study showed less operative time, less blood loss and less reduction in mean haemoglobin value postoperatively by only 1.53 gm/dl when compared with baseline values. Though complications like pain, stitch infection at surgical site and UTI was seen in few patients, all patients were mobilized within 2nd postoperative day with less rescue analgesic demand and shorter duration of hospital stay of only 8.23 days. However, plate breakage, nonunion, implant cut out, joint infection, delayed union and varus deformity was not observed in any of these patients. Moreover, Harris Hip Score showed good functional outcome. CONCLUSION: Fixation of DHS with minimal invasive technique for stable hip fracture has good functional outcome in cost effective way with fewer incidences of complications resulting in great advantage over the conventional method of fixation.

Minimal Invasive Dynamic Hip Screw Fixation for Intertrochanteric Fractures of Femur

INTRODUCTION: Good results have been achieved consistently with compression hip screw fixation for stable intertrochanteric femur fractures by conventional method. Thus, this present study was conducted to find out the outcomes for such hip fracture fixation with minimal invasive technique. MATERIALS AND METHOD: This retrospective study was carried out by collecting the records of 66 adult patients with stable intertrochanteric femur fracture managed by Dynamic Hip Screw (DHS) fixation with minimal invasive technique under Spinal Anaesthesia and Epidural Analgesia in Universal College of Medical Sciences and Teaching Hospital (UCMSTH) over a period of 3 years. The patients were in follow up visits for 1 year postoperatively. Operating time, blood loss, decrease in haemoglobin level, analgesic demand, length of hospital stay, fracture union time, early and delayed complications and functional outcome were recorded. RESULTS: This study showed less operative time, less blood loss and less reduction in mean haemoglobin value postoperatively when compared with baseline values. Though complications like pain, stitch infection at surgical site and UTI was seen in few patients, all patients were mobilized within 2nd postoperative day with less rescue analgesic demand and shorter duration of hospital stay of only 8.23 days. However, plate breakage, nonunion, implant cut out, joint infection, delayed union and varus deformity was not observed in any of these patients. Moreover, Harris Hip Score showed good functional outcome.CONCLUSION: Fixation of DHS with minimal invasive technique for stable hip fracture has good functional outcome in cost effective way with fewer incidences of complications.Journal of Universal College of Medical Sciences (2016) Vol.04 No.01 Issue 13, Page: 26-31

Reply re: Vertically Oriented Femoral Neck Fractures: A Biomechanical Comparison of 3 Fixation Constructs.

OBJECTIVES To compare the static and dynamic mechanical properties of a modified crossed cannulated screw (CS) configuration, the inverted triangle (IT) cannulated screw configuration, and a compression hip screw (CHS) with derotation screw in Pauwels type III femoral neck fractures. METHODS Thirty synthetic femora were divided into 3 groups, and vertical femoral neck osteotomies were made. Ten osteotomized femora were fixed with a CS configuration, 10 were fixed with 3 parallel screws in an IT configuration, and the remaining 10 osteotomized femora were fixed with a CHS construct. All groups were tested using a cyclic (up to 15,000 load cycles) axial loading protocol, and survivors were statically loaded to failure. Cycles to failure, load to failure, and stiffness were calculated. The Kaplan-Meier method was used to estimate survival functions and were compared among fixation methods. The relationship between construct structural properties (maximum load and stiffness) and treatment were assessed using general linear modeling. RESULTS All CHS fixation constructs survived the 15,000 cycle loading protocol. They endured longer (P = 0.034) than the CS fixation constructs (mean failure 13,332 cycles), but were not different from IT fixation constructs (mean failure 13,592 cycles). Maximum loads to failure for CS (3870 N) and IT (3756 N) fixation constructs were not different, but were less (P < 0.0001) than the maximum loads to failure for the CHS fixation constructs (5654 N). These findings parallel the results of the axial stiffness measurements: CS fixation constructs (663.01 N/mm) were not stiffer than IT fixation constructs (620.0 N/mm), but were less (P = 0.0005) than the axial stiffness of the CHS fixation constructs (1241.86 N/mm). CONCLUSIONS The biomechanical performance of the CHS fixation method was superior to both the CS fixation method and the IT fixation method using a synthetic femoral model and this test protocol. Biomechanical performance of the latter 2 groups was indistinguishable. We recommend the use of CHS with the derotational screw construct for Pauwels III femoral neck fractures whenever possible.

Bones, blood and steel: How bioelectrical impedance analysis is affected by hip fracture and surgical implants

Abstract Introduction Bioelectrical impedance analysis (BIA) is in widespread use, but there is uncertainty about its validity in patients with metal implants or after acute hip fracture and surgery. We aimed to investigate the use of single frequency tetrapolar BIA in patients with hip fracture by answering the following questions: 1) Are BIA measurements affected by recent hip fracture and surgical repair? 2) Are BIA measurements affected by the presence of metal implants used in hip fracture surgery? Setting Two hospitals in Bergen, Norway. Participants A convenience sample of 203 acute hip fracture patients. Methods Participants had their body composition measured by single frequency, tetrapolar BIA on the fractured and unfractured side of the body in the immediate postoperative period and at follow-up three months after hip fracture. Measurements from fractured and unfractured side and measurements in hospital and at follow-up were compared. BIA readings for hips treated with cannulated screws, compression hip screw and hip arthroplasty were compared. Results Resistance was lower on the side of the fractured hip compared to the unfractured side postoperatively, but not at follow-up. BIA readings did not differ by type of surgical implant. Conclusion Recent fracture and surgery influences single frequency tetrapolar BIA resistance. The presence of surgical implants in the hip do not affect BIA measurements. If BIA is used in acute hip fracture patients, the contralateral side to the fracture should be measured.

Vertically Oriented Femoral Neck Fractures: A Biomechanical Comparison of 3 Fixation Constructs.

To compare the static and dynamic mechanical properties of a modified crossed cannulated screw (CS) configuration, the inverted triangle (IT) cannulated screw configuration, and a compression hip screw (CHS) with derotation screw in Pauwels type III femoral neck fractures. Thirty synthetic femora were divided into 3 groups, and vertical femoral neck osteotomies were made. Ten osteotomized femora were fixed with a CS configuration, 10 were fixed with 3 parallel screws in an IT configuration, and the remaining 10 osteotomized femora were fixed with a CHS construct. All groups were tested using a cyclic (up to 15,000 load cycles) axial loading protocol, and survivors were statically loaded to failure. Cycles to failure, load to failure, and stiffness were calculated. The Kaplan-Meier method was used to estimate survival functions and were compared among fixation methods. The relationship between construct structural properties (maximum load and stiffness) and treatment were assessed using general linear modeling. All CHS fixation constructs survived the 15,000 cycle loading protocol. They endured longer (P = 0.034) than the CS fixation constructs (mean failure 13,332 cycles), but were not different from IT fixation constructs (mean failure 13,592 cycles). Maximum loads to failure for CS (3870 N) and IT (3756 N) fixation constructs were not different, but were less (P < 0.0001) than the maximum loads to failure for the CHS fixation constructs (5654 N). These findings parallel the results of the axial stiffness measurements: CS fixation constructs (663.01 N/mm) were not stiffer than IT fixation constructs (620.0 N/mm), but were less (P = 0.0005) than the axial stiffness of the CHS fixation constructs (1241.86 N/mm). The biomechanical performance of the CHS fixation method was superior to both the CS fixation method and the IT fixation method using a synthetic femoral model and this test protocol. Biomechanical performance of the latter 2 groups was indistinguishable. We recommend the use of CHS with the derotational screw construct for Pauwels III femoral neck fractures whenever possible.

Spatial stress distribution analysis by thermoelastic stress measurement and evaluation of effect of stress concentration on durability of various orthopedic implant devices

Toward the development of highly durable devices, we investigated the effect of the thermoelastic constants of implantable raw metals and the surface stress distribution on the durability of various types of implant device by thermoelastic stress measurement and by evaluating the effect of the stress concentration. Surface stress was dynamically calculated from the bending moment, and the modulus of a section of a device was found to be consistent with the surface stress obtained by thermoelastic stress measurement. The durability limits of various types of bone plate and compression hip screw (CHS) calculated from maximum load vs number of cycles data (L–N data) were close to the notch fatigue strength of the raw material. The concentration factor of an artificial hip stem surface was estimated by comparing the L–N data of the stem and the S–N curve of the raw material. The dynamic analysis of durability by thermoelastic stress measurement is useful for selecting the worst case (a product deteriorating to the most severe state) in medical device design.