PURPOSE: The treatment and outcome of tibial stress fractures concomitant with knee osteoarthritis (OA) are complicated. The aim of this study was to evaluate the functional and radiological outcome of total knee arthroplasty with long tibial stem as a treatment for patients having knee OA and tibial stress fracture. METHODS: Patients who were diagnosed to have proximal tibia stress fracture along with knee OA at our institution between June 2013 and November 2018 were included in our study. All patients underwent total knee arthroplasty with long tibial stem. Preoperative and postoperative functional assessments were done according to range of movement of the knee joint, knee society score and knee injury and OA outcome score. Descriptive analysis was carried out by mean and standard deviation for quantitative variables, frequency and proportion for categorical variables. RESULTS: Twelve patients were included in the study. All patients were found to have stress fractures in the proximal half of tibia and extra-arthrosis. Four patients had non-union/delayed union, and 8 patients had acute fractures. The average preoperative range of movement was 88.1°, which improved to 116.3° at 3 months following surgery. It was found that the fracture has healed in all cases. Mean knee society score improved from 32.9 preoperatively to 89.3 at 1 year follow-up. Knee injury and OA outcome score improved from a mean score of 28.3 preoperatively to 81.1 at 1 year follow-up. CONCLUSION Stress fractures can occur in the proximal tibia in patients with knee OA. Total knee arthroplasty with tibial stem provides a suitable solution for both conditions. Additional plating or bone graft is unlikely to be required.
Humans ; Arthroplasty, Replacement, Knee/adverse effects* ; Osteoarthritis, Knee/surgery* ; Tibia/surgery* ; Fractures, Stress/surgery* ; Tibial Fractures ; Knee Joint ; Knee Injuries/surgery* ; Treatment Outcome

Biodynamics of mandibular angle fractures has been extensively discussed in the literature in search for the best way to fixate and expedite recovery of trauma patients. Pioneers like Michelet and Champy had the greatest impact on evolving of osteosynthesis in maxillofacial traumatology; they introduced their basic principles frequently used to describe the biomechanics of mandibular fixation. Their concept states when a physiologic load is applied on mandibular teeth a negative tension will be created at superior border and a positive pressure will appear at inferior border. These simple definitions are the basis for the advent of fixation modalities in mandibular angle fracture. This article sought to reassess these principals based on load location via finite elements method.
Biomechanical Phenomena ; Dental Stress Analysis ; Finite Element Analysis ; Fracture Fixation, Internal ; methods ; Humans ; Mandible ; physiopathology ; Mandibular Fractures ; physiopathology ; surgery ; Tooth ; physiology

INTRODUCTIONAnatomical markers can help to guide lag screw placement during surgery for internal fixation of fifth metatarsal base fractures. This study aimed to identify the optimal anatomical markers and thus reduce radiation exposure.

METHODSA total of 50 patients in Huashan Hospital, Shanghai, China, who underwent oblique foot radiography in the lateral position were randomly selected. The angles between the fifth metatarsal axis and cuboid articular surface were measured to determine the optimal lag screw placement relative to anatomical markers.

RESULTSThe line connecting the styloid process of the fifth metatarsal base with the second metatarsophalangeal (MTP) joint intersected with the fifth metatarsal base fracture line at an angle of 86.85° ± 5.44°. The line connecting the fifth metatarsal base styloid with the third and fourth MTP joints intersected with the fracture line at angles of 93.28° ± 5.24° and 100.95° ± 5.00°, respectively. The proximal articular surface of the fifth metatarsal base intersected with the line connecting the styloid process of the fifth metatarsal base with the second, third and fourth MTP joints at angles of 24.02° ± 4.77°, 30.79° ± 4.53° and 38.08° ± 4.54°, respectively.

CONCLUSIONThe fifth metatarsal base styloid and third MTP joint can be used as anatomical markers for lag screw placement in fractures involving the fifth tarsometatarsal joint. The connection line, which is normally perpendicular to the fracture line, provides sufficient mechanical stability to facilitate accurate screw placement. The use of these anatomical markers could help to reduce unnecessary radiation exposure for patients and medical staff.

Bone Screws ; China ; Foot ; Fracture Fixation, Internal ; Fractures, Bone ; surgery ; Humans ; Metatarsal Bones ; radiation effects ; surgery ; Patient Positioning ; Radiation Exposure ; Radiography ; Stress, Mechanical

BACKGROUNDOpen reduction and internal fixation with plate and screws are the gold standard for the surgical treatment of humeral shaft fractures, this study was to compare the mechanical properties of anteromedial, anterolateral, and posterior plating for humeral shaft fractures.

METHODSA distal third humeral shaft fracture model was constructed using fourth-generation sawbones (#3404, composite bone). A total of 24 sawbones with a distal third humeral shaft fracture was randomly divided into three Groups: A, B, and C (n = 8 in each group) for anteromedial, anterolateral, and posterior plating, respectively. All sawbones were subjected to horizontal torsional fatigue tests, horizontal torsional and axial compressive fatigue tests, four-point bending fatigue tests in anteroposterior (AP) and mediolateral (ML) directions and horizontal torsional destructive tests.

RESULTSIn the horizontal torsional fatigue tests, the mean torsional angle amplitude in Groups A, B, and C were 6.12°, 6.53°, and 6.81°. In horizontal torsional and axial compressive fatigue tests, the mean torsional angle amplitude in Groups A, B, and C were 5.66°, 5.67°, and 6.36°. The mean plate displacement amplitude was 0.05 mm, 0.08 mm, and 0.10 mm. Group A was smaller than Group C (P < 0.05). In AP four-point bending fatigue tests, the mean plate displacement amplitude was 0.16 mm, 0.13 mm, and 0.20 mm. Group B was smaller than Group C (P < 0.05). In ML four-point bending fatigue tests, the mean plate displacement amplitude were 0.16 mm, 0.19 mm, and 0.17 mm. In horizontal torsional destructive tests, the mean torsional rigidity in Groups A, B, and C was 0.82, 0.75, and 0.76 N·m/deg. The yielding torsional angle was 24.50°, 25.70°, and 23.86°. The mean yielding torque was 18.46, 18.05, and 16.83 N·m, respectively.

CONCLUSIONSAnteromedial plating was superior to anterolateral or posterior plating in all mechanical tests except in AP four-point bending fatigue tests compared to the anterolateral plating group. We can suggest that anteromedial plating is a clinically safe and effective way for humeral shaft fractures.

Biomechanical Phenomena ; Bone Plates ; Fracture Fixation, Internal ; Humans ; Humeral Fractures ; surgery ; Humerus ; surgery ; Models, Anatomic ; Stress, Mechanical

The presence of large segmental defects of the diaphyseal bone is challenging for orthopedic surgeons. Free vascularized fibular grafting (FVFG) is considered to be a reliable reconstructive procedure. Stress fractures are a common complication following this surgery, and hypertrophy is the main physiological change of the grafted fibula. The exact mechanism of hypertrophy is not completely known. To the best of our knowledge, no studies have examined the possible relationship between stress fractures and hypertrophy. We herein report three cases of patients underwent FVFG. Two of them developed stress fractures and significant hypertrophy, while the remaining patient developed neither stress fractures nor significant hypertrophy. This phenomenon indicates that a relationship may exist between stress fractures and hypertrophy of the grafted fibula, specifically, that the presence of a stress fracture may initiate the process of hypertrophy.
Adult ; Female ; Fibula ; pathology ; transplantation ; Fractures, Stress ; pathology ; Humans ; Hypertrophy ; Male ; Middle Aged ; Tibia ; surgery ; Tibial Fractures ; surgery

Scaphoid stress fracture is rare and occurs mainly in gymnasts. The current literature has only two reported cases: unilateral scaphoid stress fracture in a platform diver and bilateral scaphoid stress fracture in a gymnast. We herein report bilateral stress fracture of the scaphoid in a platform diver who presented with only one symptomatic side. Our patient was a 16-year-old competitive platform diver with an 18-month history of pain in the right wrist. Radiography revealed fracture of the right scaphoid at the waist. As part of our preoperative plan of measuring the scaphoid length to determine the appropriate screw, radiography of the contralateral side was performed, revealing an unexpected fracture of the left scaphoid. Due to the frequency of stress fractures in competitive sports, especially gymnastics, we recommend that bilateral scaphoid radiography be performed for athletes presenting with a unilateral scaphoid fracture, to avoid missing a fracture in the contralateral side.
Adolescent ; Diving ; injuries ; Fractures, Stress ; diagnostic imaging ; surgery ; Humans ; Male ; Radiography ; Scaphoid Bone ; injuries ; surgery

BACKGROUNDPrevious studies have suggested that percutaneous vertebroplasty might alter vertebral stress transfer, leading to adjacent vertebral failure. However, no three-dimensional finite element study so far accounted for the stress distributions on different cement volumes. The purpose of this study was to evaluate the stress distributions on the endplate under different loading conditions after augmentation with various volumes of bone cement.

METHODSL2-L3 motion segment data were obtained from CT scans of the lumbar spine from a cadaver of a young man who had no abnormal findings on roentgenograms. Three-dimensional model of L2-L3 was established using Mimics software, and finite element model of L2-L3 functional spinal unit (FSU) was established using Ansys10.0 software. For simulating percutaneous vertebral augmentation, polymethylmethacrylate (PMMA) was deposited into the bipedicle of the L2 vertebra. The percentage of PMMA volume varied between 15% and 30%. The stress distributions on the endplate of the augmented vertebral body were calculated under three different loading conditions.

RESULTSIn general, the stress level monotonically increased with bone cement volume. Under each loading condition, the stress change on the L2 superior and inferior endplates in three kinds of finite element models shows monotonic increase. Compared with the stress-increasing region of the endplate, the central part of the L2 endplate was subject to the greatest stress under three kinds of loading conditions, especially on the superior endplate and under flexion.

CONCLUSIONSThe finite element models of FSU are useful to optimize the planning for vertebroplasty. The bone cement volume might have an influence on the endplate of the augmentation, especially the superior endplate. It should be noted that the optimization of bone cement volume is patient specific; the volume of the bone cement should be based on the size, body mineral density, and stiffness of the vertebrae of individual patients.

Bone Cements ; therapeutic use ; Finite Element Analysis ; Humans ; Osteoporosis ; Spinal Fractures ; surgery ; Stress, Mechanical ; Vertebroplasty ; methods

OBJECTIVETo investigate the feasibility of hip arthroplasty in the treatment of elderly patients with Evans I-III intertrochanteric fracture of femur by analyzing its biomechanics characters.

METHODSWe solved the CT digital image files with the graphics processing software Mimics at DICOM 3.0 standard, and reconstructed the three-dimensional entity of femur with CAD modeling software Unigraphics. Then the fracture line was defined in the model as the line between the tip of greater trochanter and inferior margin of small trochanter, above which the upper bone was removed. Afterwards the two prosthesises with different stem lengths (120 mm and 170 mm) were implanted into the fracture model respectively as hip arthroplasty with 3 mm bone cement layer between prosthesis and femur, and the bone defect was repatched with 5 mm bone cement layer. A three-dimensional finite element model was established with finite element analysis software ABAQUS 6.5. We formulated different material parameters under the stress condition standing with single leg to build the stress distribution map of the femur prosthesis, and took 5 loci of region of stress concentration to calculate the mean value of stress.

RESULTSThe stress distribution maps of the short and long stem length prothesises were similar. And there were two areas of stress concentration, including the upper portion and the lower portion close to the joint of the prosthesis stem, and the stress concentration in the junction part was obviously between the lower portion and the upper area of the small trachanter. The stress reached the first concentration area at the junction and then gradually reached the second concentration area at the interior terminal of the stem. While the stress gradually increased along the lateral prosthesis stem, and reached the stress concentration area at the end.

CONCLUSIONSThe stress distribution maps in the femur prosthesises are similar between hip arthroplasty in the treatment of intertrochanteric fracture of femur and the traditional hip arthroplasty surgery. The peak stress values are higher in the long stem prosthesis in the treatment of intertrochanteric fracture of femur than the short type, while they are under the rupture value of the metal.

Aged ; Arthroplasty, Replacement, Hip ; instrumentation ; methods ; Biomechanical Phenomena ; Bone Cements ; Computer Simulation ; Female ; Finite Element Analysis ; Hip Fractures ; surgery ; Hip Prosthesis ; Humans ; Image Processing, Computer-Assisted ; Software ; Stress, Mechanical

The purpose of this study was to compare monotonic biomechanical properties of gourd-shaped LCP fixation with LCP fixation of human tibial shaft in gap fracture mode. Twenty paired fresh cadaveric human tibias were randomly divided into 4 groups (5 pairs each): (1) axial loading single cycle to failure testing, (2) torsion single cycle to failure testing, (3) 4-point bending single cycle to failure testing, and (4) dynamic 4-point bending testing. A 7-hole 4.5 mm gourd-shaped LCP was secured on the anteromedial surface of 1 randomly selected bone from each pair, respectively, using 6 locking screws in the 1st, 2nd, 3rd, 5th, 6th and 7th hole with the middle hole unfilled and just located at the mid-diaphysis of the tibia. A 7-hole 4.5 mm LCP was secured on the other bone with the same method. Standard AO/ASIF techniques were used. After fixation finished, a 10 mm gap in the mid-diaphysis of tibia was created, centrally located at the unfilled hole. The axial, torsional, and bending stiffness and failure strengths were calculated from the collected data in static testings and statistically compared using paired Student's t-test. The 4-point bending fatigue lives of the two constructs were calculated from the dynamic testing data and also statistically compared using paired Student's t-test. Failure modes were recorded and visually analyzed. P<0.05 was considered significant. Results showed that the axial, torsional and bending stiffness of gourd-shaped LCP construct was greater (4%, 19%, 12%, respectively, P<0.05) than that of the LCP construct, and the axial, torsional and bending failure strengths of gourd-shaped LCP construct were stronger (10%, 46%, 29%, respectively, P<0.05) than those of the LCP construct. Both constructs failed as a result of plate plastic torsional deformation. After axial loading and 4-point bending testings, LCP failed in term of an obvious deformation of bent apex just at the unfilled plate hole, while the gourd-shaped LCP failed in term of a deformation of bent arc between the 3rd and 5th holes, which indicated a more consistent stress distribution on gourd-shaped LCP. Fatigue life of gourd-shaped LCP construct was significantly greater than LCP construct (153 836±2 228 vs. 132 471±6 460 cycles, P<0.01). All constructs failed as a result of fracture of the plate through the compression hole of the unfilled combination screw hole. The biomechanical testing showed that gourd-shaped LCP can provide greater stiffness and strength, and longer fatigue life than LCP. The gourd-shaped LCP may be more advantageous mechanically and may reduce the plate breakage rate clinically.
Bone Plates ; Compressive Strength ; Elastic Modulus ; Equipment Failure Analysis ; Fracture Fixation, Internal ; instrumentation ; Humans ; In Vitro Techniques ; Prosthesis Design ; Stress, Mechanical ; Tensile Strength ; Tibial Fractures ; physiopathology ; surgery

Femoral neck stress fractures (FNSFs) are rare, constituting only 5% of all stress fractures in young adults. These fractures are usually seen in athletes, military recruits and patients with underlying metabolic diseases. The treatment of FNSFs is still controversial because of the inherent complications associated with the treatment procedure. We came across 4 cases of bilateral FNSFs in non-athletic individuals who were manual labourers without underlying bony disorders. Two patients with FNSFs and coxa vara deformity on both sides were managed by subtrochanteric valgus osteotomy and dynamic hip screw fixation. One of the remaining two patients was treated by cannulated cancellous screw fixation on one side and subtrochanteric valgus osteotomy on the other side. The fourth patient received subtrochanteric valgus osteotomy on one side and bipolar hemiarthroplasty on the other side after failed cannulated screw fixation. All the fractures healed without any complications. No evidence of avascular necrosis or arthritis was noted in our series. Subtrochanteric valgus osteotomy restores normal neck-shaft angle in patients suffering from FNSFs combined with coxa vara deformity. Moreover, it helps to bring the forces acting around the hip to normal biomechanical levels, leading to fracture union and better results. Replacement arthroplasty is recommended to patients who fail to achieve bony union after fixation.
Adult ; Bone Screws ; Female ; Femoral Neck Fractures ; surgery ; Fracture Fixation, Internal ; methods ; Fracture Healing ; Fractures, Stress ; surgery ; Hemiarthroplasty ; Humans ; Male ; Middle Aged ; Osteotomy