Re-understanding the value of the tip-apex distance theory in guiding treatment of intertrochanteric femoral fracture / 中华创伤杂志

Intertrochanteric femoral fracture occurs frequently in elderly osteoporotic patients, with high disability and mortality, for which surgical treatment is necessary. Common surgical modalities for intertrochanteric femoral fracture include intramedullary and extramedullary internal fixation systems, but neither can avoid the complications like internal fixation cut-out or internal fixation cut-through of the femoral head after surgery. The tip-apex distance theory was once considered to be of great significance in avoiding internal fixation cut-out, with the mainstream view was that screw cut-out could be avoided to the maximum extent when the tip-apex distance was ≤25 mm. However, internal fixation that meets the criteria of the tip-apex distance theory may also show cut-out and "Z-effect" in clinical practice, which lacks a reasonable explanation. Based on the lever balance reconstruction theory and the buttress-stretch effect, the author re-understands the value of the tip-apex distance theory in guiding treatment of intertrochanteric femoral fracture, hoping to propose an enlightenment for the treatment of intertrochanteric femoral fracture.

Chinese expert consensus on the diagnosis and treatment of osteoporotic periarticular fracture of the shoulder in the elderly (version 2023) / 中华创伤杂志

Periarticular fracture of the shoulder is a common type of fractures in the elderly. Postoperative adverse events such as internal fixation failure, humeral head ischemic necrosis and upper limb dysfunction occur frequently, which seriously endangers the exercise and health of the elderly. Compared with the fracture with normal bone mass, the osteoporotic periarticular fracture of the shoulder is complicated with slow healing and poor rehabilitation, so the clinical management becomes more difficult. At present, there is no targeted guideline or consensus for this type of fracture in China. In such context, experts from Youth Osteoporosis Group of Chinese Orthopedic Association, Orthopedic Expert Committee of Geriatrics Branch of Chinese Association of Gerontology and Geriatrics, Osteoporosis Group of Youth Committee of Chinese Association of Orthopedic Surgeons and Osteoporosis Committee of Shanghai Association of Chinese Integrative Medicine developed the Chinese expert consensus on the diagnosis and treatment of osteoporotic periarticular fracture of the shoulder in the elderly ( version 2023). Nine recommendations were put forward from the aspects of diagnosis, treatment strategies and rehabilitation of osteoporotic periarticular fracture of the shoulder, hoping to promote the standardized, systematic and personalized diagnosis and treatment concept and improve functional outcomes and quality of life in elderly patients with osteoporotic periarticular fracture of the shoulder.

Guideline for clinical perioperative care of orthopedic trauma patients in the new stage of novel corona virus infection (version 2023) / 中华创伤杂志

As the National Health Commission changes the management of novel corona virus infection, the situation and preventive policies for controlling the epidemic have also entered a new stage in China. Perioperative care strategies for orthopedic trauma such as designated isolation and nucleic acid test screening have also been adjusted in the new stage. Based on the perioperative work experiences in the new stage of epidemic from the frontline anti-epidemic staff of orthopedics in domestic hospitals and combined with the literature and relevant evidence-based medical data in perioperative care of orthopedic trauma patients under the current anti-epidemic policies at home and abroad, Chinese Orthopedic Association and Chinese Society of Traumatology organized relevant experts to formulate the Guideline for clinical perioperative care of orthopedic trauma patients in the new stage of novel corona virus infection ( version 2023). The guideline summarized 16 recommendations from the aspects of preoperative diagnosis and treatment, infection prevention, emergency operation and postoperative management to systematically standardize the perioperative clinical pathways, diagnosis and treatment processes of orthopedic trauma in the new stage of novel corona virus infection, so as to provide a guidance and reference for hospitals at all levels to carry out relevant work in current epidemic control policies.

Guideline for the diagnosis and treatment of chronic refractory wounds in orthopedic trauma patients (version 2023) / 中华创伤杂志

Chronic refractory wound (CRW) is one of the most challengeable issues in clinic due to complex pathogenesis, long course of disease and poor prognosis. Experts need to conduct systematic summary for the diagnosis and treatment of CRW due to complex pathogenesis and poor prognosis, and standard guidelines for the diagnosis and treatment of CRW should be created. The Guideline forthe diagnosis and treatment of chronic refractory wounds in orthopedic trauma patients ( version 2023) was created by the expert group organized by the Chinese Association of Orthopedic Surgeons, Chinese Orthopedic Association, Chinese Society of Traumatology, and Trauma Orthopedics and Multiple Traumatology Group of Emergency Resuscitation Committee of Chinese Medical Doctor Association after the clinical problems were chosen based on demand-driven principles and principles of evidence-based medicine. The guideline systematically elaborated CRW from aspects of the epidemiology, diagnosis, treatment, postoperative management, complication prevention and comorbidity management, and rehabilitation and health education, and 9 recommendations were finally proposed to provide a reliable clinical reference for the diagnosis and treatment of CRW.

Expert consensus on diagnosis, prevention and treatment of perioperative lower extremity vein thrombosis in orthopedic trauma patients (2022 edition) / 中华创伤杂志

Lower extremity deep vein thrombosis (DVT) is one of the main complications in patients with traumatic fractures, and for severe patients, the DVT can even affect arterial blood supply, resulting in insufficient limb blood supply. If the thrombus breaks off, pulmonary embolism may occur, with a high mortality. The treatment and rehabilitation strategies of thrombosis in patients with lower extremity fractures have its particularity. DVT in traumatic fractures patients has attracted extensive attention and been largely studied, and the measures for prevention and treatment of DVT are constantly developing. In recent years, a series of thrombosis prevention and treatment guidelines have been updated at home and abroad, but there are still many doubts about the prevention and treatment of DVT in patients with different traumatic fractures. Accordingly, on the basis of summarizing the latest evidence-based medical evidence at home and abroad and the clinical experience of the majority of experts, the authors summarize the clinical treatment and prevention protocols for DVT in patients with traumatic fractures, and make this consensus on the examination and assessment, treatment, prevention and preventive measures for DVT in patients with different fractures so as to provide a practicable approach suitable for China ′s national conditions and improve the prognosis and the life quality of patients.

Curative effects of Nice knot fixation on tuberosity healing in hemiarthroplasty for complex proximal humeral fractures / 中华创伤骨科杂志

Objective:To explore the curative effects of Nice knot fixation on tuberosity healing in hemiarthroplasty for complex proximal humeral fractures.Methods:A retrospective analysis was conducted of the eligible 32 complex proximal humeral fractures which had been treated at Department of Trauma and Orthopedics, Peking University People's Hospital between May 1, 2016 and May 1, 2019. Nice knot fixation was used to repair greater and lesser tuberosities in hemiarthroplasty for all the patients. There were 6 males and 26 females, aged from 60 to 90 years (mean, 74.9 years). By the Neer classification, there were 4 three-part fractures combined with dislocation, 20 four-part fractures, and 8 four-part fractures combined with dislocation. Shoulder joint X-rays were taken at postoperative 1, 2, 3, 6, and 12 months at the outpatient clinic to evaluate the patients' shoulder joint mobility, visual analog scale (VAS) pain score and Constant-Murley shoulder score. Tuberosity healing was assessed based on the X-rays and related complications were recorded.Results:The 32 patients received complete follow-up for 12 to 25 months (average, 17.82 months). At the 12-month follow-up, their shoulder flexion averaged 131.3° (from 80° to 155°), abduction 126.9° (from 80° to 155°), external rotation 48.4° (from 30° to 60°), internal rotation the L2 level, VAS pain score 0.9 (from 0 to 5), and Constant-Murley score 83.4 (from 58 to 96). The rate of patient satisfaction was 87.5%(28/32). Tuberosity-related complications were observed in 6 cases with an incidence of 18.8%. Complications like infection and prosthetic loosening were found in none of the patients.Conclusion:In hemiarthroplasty for complex proximal humeral fractures, application of Nice knot to fixate greater and lesser tuberosities can lead to rigid fixation, definite curative effects and a low incidence of tuberosity-related complications.

Buttress and stretch effect of internal fixation for femoral intertrochanteric fractures / 中华骨科杂志

Intertrochanteric fractures of femur are common osteoporotic fractures in the elderly, and internal fixation is the preferred treatment method. The purpose is to use internal fixators to share the load conducted by the hip joint. Most of the current researches focus on theories of the lateral wall, medial wall, apex distance, and ratchet mechanism etc of the proximal femur. However, neither the extramedullary nor the intramedullary designs of single head-neck screws or double head-neck screws based on these theories can completely avoid the occurrence of femoral head penetration. According to the distribution of trabecular bone in proximal femur and the biomechanical change characteristics before and after fracture, the lever-balance reconstruction theory was proposed, and the therapy clarified the dynamic changes of stress on head-neck screws after internal fixation. On the basis of this theory, the author further proposed the buttress and stretch effect that affected the stability of internal fixation of femoral intertrochanteric fractures, and clarified the causes and mechanisms of internal fixation screw penetration of femoral head after fracture operation. In view of this effect, it is recommended to use proximal femoral bionic nail (PFBN) for the treatment of femoral intertrochanteric fractures to prevent the screw from penetrating the femoral head, providing a new idea for the internal fixation of intertrochanteric fractures in the future.

A new understanding of internal fixation for long shaft fractures -- lever reconstruction theory / 中华骨科杂志

Through the study of the anatomy and biomechanical characteristics of the long bone after internal fixation of fracture, researches showed that a new level system is formed. The intersection of fracture line and internal fixation serves as the fulcrum. The distance from external force point to fulcrum is power arm, and the distance from the fulcrum to the tail of internal fixation contacting bone is the resistance arm, and the power arm and resistance arm should be as equal as possible. This is the lever reconstruction theory. Plate and intramedullary nail fixation are commonly used in the treatment of long shaft fractures. The intramedullary nail mainly depends on the contact between the main nail and the inner wall of the medullary cavity, and the firmness of distal locking nail and the bone. According to the lever reconstruction theory, after intramedullary nail fixation, the power arm is the distance from the point of external force to the fulcrum, and the resistance arm is the distance from the fulcrum to the contact point of nail tail and bone. The intramedullary nail should be fully reamed before inserting and the main nail with larger diameter should be used to make it closely fit with the inner wall, and contact should be increased through distal locking to prolong the effective working distance. Plate fixation depends on the holding force between the distal screw and bone, which can increase the reliability of fixation. The power arm is the distance from the point of external force to the fulcrum, and the resistance arm is the distance from the fulcrum to the end of the opposite side. The type of lever formed varies with the location of the fracture. For example, if the power arm is shorter than or equal to the resistance arm, it can form a laborious lever or balance lever with stable structure. When the power arm is longer than the resistance arm, absolute stability cannot be achieved and it is prone to complications such as nonunion and fixation failure. At this time, effective working distance of the resistance arm should be extended and scientific and effective rehabilitation guidance should be given according to different fracture types. This theory can well explain the causes of complications related to internal fixation after long shaft fractures and point out a new direction for future treatment.

Re-recognition of the role of lateral wall of proximal femur based on the theory of lever-pivot balance / 中华创伤杂志

Early internal fixation for intertrochanteric fracture of the femur can improve the quality of patients′ life and reduce disability and mortality. In the past, treatment of intertrochanteric fracture of the femur had some problems, such as head and neck screw cut-out, hip varus deformity, nail withdrawal, femoral neck shortening, and internal fixator fracture, etc., for which no reasonable explanation could be provided. The "lateral wall" theory has been recognized by most scholars and used to guide the development and clinical application of internal fixation, which has not entirely avoided the occurrence of the complications mentioned above. A correct understanding of the mechanics of the lateral wall of the proximal femur helps choose a reasonable internal fixation method for the treatment of intertrochanteric fracture of the femur to reduce the incidence of complications. The author firstly discusses the lateral wall measuring and fixation strengthening methods, reasonably explore the reasons for postoperative complications according to the theory of lever-pivot balance, and proposes that the proximal femoral bionic nail (PFBN) is an ideal choice for the treatment of intertrochanteric fracture of the femur.

Reason for failed fixation with dynamic hip screws for intertrochanteric fracture: analysis based on the lever-balance-reconstruction theory / 中华创伤骨科杂志

Objective:To study the reason for failed fixation with dynamic hip screws (DHS) and the indications for DHS fixation in the treatment of intertrochanteric fracture based on the lever-balance-reconstruction theory.Methods:A retrospective analysis was performed of the data of 32 patients with intertrochanteric fracture who had been treated by DHS fixation at Department of Orthopaedic Trauma, Peking University People's Hospital from January 1999 to December 2019. There were 22 males and 10 females, aged from 34 to 91 years (average, 67.7 years). By the AO classification, 15 fractures were type 31-A1, 13 ones type 31-A2, and 4 ones type 31-A3. According to the lever-balance-reconstruction theory, after the position of postoperative fulcrum was determined depending on the relationship between fracture line and internal fixation, the medial and lateral force arms were measured after internal fixation. The 32 patients were divided into 2 groups according to the position of fulcrum after internal fixation. In group A of 13 patients, the fulcrum was located in or within the center of the medullary cavity; in group B of 19 patients, the fulcrum was located outside the center of the medullary cavity. The incidence of internal fixation failure was compared between the 2 groups.Results:Internal fixation failure occurred in 15 of the 32 patients: cutting out of the head and neck screws without penetration in 2 cases, screw withdrawal in 8 cases, hip varus deformity in 10 cases, and femoral neck shortening in 15 cases. The 2 groups were comparable because there were no statistically significant differences in their preoperative general data or types of internal fixation between them except AO classification ( P>0.05). The length of medial force arm (power arm) averaged 51.12 mm (from 39.4 to 57.9 mm) and the length of lateral force arm (resistance arm) 23.37 mm (from 15.1 to 31.0 mm) in group A where 3 patients experienced internal fixation failure after operation; the length of medial force arm (power arm) averaged 63.71 mm (from 52.3 to 74.5 mm) and the length of lateral force arm (resistance arm) 9.94 mm (from 3.1 to 18.3 mm) in group B where 12 patients experienced internal fixation failure after operation. There was a significant difference between the 2 groups in internal fixation failure ( P=0.036). Conclusions:In the DHS fixation of intertrochanteric fracture, the postoperative fixation failure is associated with the fulcrum position after reconstruction. DHS is only indicated for intertrochanteric fractures whose fracture line (post-reconstruction fulcrum) is near and inside the center of the medullary cavity, but not for those whose fracture line (post-reconstruction fulcrum) is outside the medullary cavity.

Review and prospect of total hip arthroplasty with collum femoris preserving prosthesis based on lever reconstruction balance theory / 中华骨科杂志

Collum femoris preserving (CFP) is a surgical approach that emphasizes bone preservation, which can improve the stress distribution of the proximal femur, especially for young and active patients. Although the conventional CFP prosthesis has excellent short-term and medium-term clinical outcomes, and bone stock preservation is better than traditional total hip arthroplasty, it has not shown a higher prosthetic survival rate, which limits the broad application of CFP prosthesis. Compared with the conventional total hip prosthesis stem, the conventional CFP prosthesis improved the compressive stress transfer mechanism by retaining the femoral neck and moving the reconstruction fulcrum inward, neglecting the mechanical reconstruction of tensile stress transfer. Based on the theory of lever reconstruction balance, the bionic collum femoris preserving (BCFP) stem achieves the medial migration of the fulcrum based on preserving the femoral neck and proximal femoral bone and reconstructs the tension stress transmission mechanism through tension screws to reduce the stress shielding effect and improve the stress distribution. In addition to enhancing the initial stability of the prosthesis, the bionic fixation of the prosthesis is realized. Traditional total hip prosthesis and CFP prosthesis are plagued by long-term complications such as aseptic loosening and periprosthetic fractures. The innovative design of the BCFP prosthesis is expected to break new ground in addressing the longevity of the hip prosthesis.

Characteristics and causes of complications after internal fixation of femoral neck fractures based on OTA/AO classification / 中华创伤杂志

Objective:To investigate the characteristics of complications after internal fixation with hallo nails for femoral neck fractures according to OTA/AO classification and analyze the reasons for differences in complications of different classifications based on the current theories and lever-fulcrum balance theory.Methods:A retrospective case series analysis was made on clinical data of 113 patients with femoral neck fractures treated in Peking University People's Hospital from January 2014 to June 2020. There were 49 males and 64 females, with the age of 21-89 years [61(52, 72)years]. According to OTA/AO classification, there were 5 patients with type B1.1 fractures, 18 with type B1.2, 16 with type B1.3, 44 with type B2.1, 5 with type B2.2, 12 with type B2.3 and 13 with type B3. All patients were treated by percutaneous internal fixation with hallo nails. Complications were recorded during follow-up including femoral head necrosis, nonunion, screw back-sliding and screw cut-out. Causes of internal fixation complications were analyzed based on the lever-fulcrum balance theory, taking the location of fulcrum, screw stress (F1), force arm of pressure (L1), resistance of screw (F2) and resistance side (L2) into consideration.Results:All patients were followed up for 1.1-77.5 months [8.2(3.6, 16.6)months]. In all, 24 patients had complications, including femoral head necrosis in 7 patients, nonunion in 3, screw back-sliding in 12 and screw cut-out in 2. The rate of femoral head necrosis of type B1, B2 and B3 was 15%(6/39), 2% (1/61) and 0%, respectively. The rate of femoral head necrosis of type B1 was higher than type B2 ( P<0.05). The nonunion rate was 3%(1/39) in type B1, 3%(2/61) in type B2, and 0% in type B3 ( P>0.05). The rate of screw back-sliding of type B1, B2 and B3 was 3%(1/39), 2%(1/61) and 0%, respectively. The rate of screw back-sliding of type B2.3 and B3 were higher than that of type B1 ( P<0.05). A trend toward a higher rate of screw back-sliding of type B2.3 and B3 was found when compared to type B2.1/2.2, but there was no significant difference ( P>0.05). Moreover, the rate of screw back-sliding showed no significant difference between type B2.3 and B3 ( P>0.05). The rate of screw cut-out was 3%(1/39) in type B1, 2%(1/61) in type B2, and 0% in type B3, which showed no significant difference between type B1 and B2 ( P>0.05). According to the lever-fulcrum balance theory, the extent of pathologic fulcrum of type B1, B2 and B3 gradually increased, resulting in increased L1 and decreased L2. The L1 of type B1, B2 and B3 was (2.2±0.5)cm, (2.8±0.4)cm and (4.7±0.5)cm, respectively ( P<0.01). The L2 of type B1, B2 and B3 was (5.1±0.5)cm, (4.7±0.5)cm, and (3.6±0.4)cm, respectively ( P<0.01). Therefore, the F1 of type B1, B2 and B3 increased progressively. Conclusions:After internal fixation, the rate of femoral head necrosis of type B1 is significantly higher than that of type B2, and the rate of screw back-sliding of type B1 is significantly lower than that of type B3. The lever-fulcrum balance theory can deepen our knowledge of reasons for complications after operation for femoral neck fractures.

Analysis of characteristics and causes of postoperative invalid fixation failures of femoral intertrochanteric fractures / 中华创伤杂志

Objective:To investigate the characteristics of postoperative internal fixation failures of femoral intertrochanteric fractures and analyze the related reasons using the leverage-balance-reconstruction theory.Methods:A retrospective case series study was performed for 40 patients suffering from implant failure after internal fixation of femoral intertrochanteric fractures admitted to Peking University People's Hospital from January 1999 to December 2019. There were 20 males and 20 females, aged from 43 to 92 years [(74.1±11.5)years]. The patients were assigned to extramedullary fixation (extramedullary fixation group, 17 patients) and intramedullary fixation (intramedullary fixation group, 23 patients). Complications associated with internal fixation were recorded, including internal fixation cutout, coxa vara deformity of hip joint, internal fixation withdrawal, femoral heck shortening and internal fixation breakage. Based on the lever-balance-reconstruction theory, the failure reasons of internal fixation were analyzed in combination with the change of arm length and outward shift of fulcrum measured before operation, after internal fixation and after fixation failure.Results:Among 40 patients, internal fixation cutout occurred in 18 patients, coxa vara deformity of hip joint in 37, internal fixation withdrawal in 29, femoral neck shortening in 37 and internal fixation breakage in 3. In extramedullary fixation group, the lengths of primary power arm and resistance arm were (8.0±1.0)mm and (59.4±10.9)mm, the lengths of power arm and resistance arm after fixation were (72.7±21.7)mm and (8.9±7.4)mm, the lengths of power arm and resistance arm after fixation failure were (50.3±14.9)mm and (33.6±17.6)mm. In intramedullary fixation group, the lengths of primary power arm and resistance arm were (6.7±0.6)mm and (49.8±9.9)mm, the lengths of power arm and resistance arm after fixation were (51.5±7.0)mm and (19.8±5.9)mm, the lengths of power arm and resistance arm after fixation failure were (41.6±9.6)mm and (32.4±7.7)mm. In each group, the lengths of power arm and resistance arm after internal fixation showed significant differences from that of normal ones and from that after fixation failure ( P<0.05). The length of power arm in extramedullary fixation group was larger than that in intramedullary fixation group ( P<0.05). The shortening of power arm in extramedullary fixation group was larger than that in intramedullary fixation group after fixation failure ( P<0.05). Conclusions:The extramedullary and intramedullary fixation of femoral intertrochanteric fractures result in the displacement of reconstruction fulcrum. The shortening of power arm is observed after fixation failure. The leverage-balance-reconstruction theory is helpful to analyze the cause of complications. The power arm after extramedullary fixation is longer than that after intramedullary fixation and is therefore more prone to fixation failure. The primary cause of postoperative internal fixation complications is to achieve a new balance of leverage.

Failure analysis in proximal femoral nail antirotation fixation for intertrochanteric fractures / 中华创伤骨科杂志

Objective:To analyze the causes and risk factors for failure of internal fixation with proximal femoral nail antirotation (PFNA) in the treatment of femoral intertrochanteric fractures.Methods:A retrospective analysis was conducted of the 568 patients with femoral intertrochanteric fracture who had been treated with PFNA fixation at Department of Orthopaedic Surgery, The Fifth Central Hospital of Tianjin from March 2013 to March 2018. They were 348 males and 220 females, aged from 44 to 93 years (average, 74.6 years). According to the fracture stability classification, the patients were divided into a stable group of 424 cases and an unstable group of 144 cases. According to the AO classification, the stable group had type 31-A1 and type 31-A2.1 while the unstable group type 31-A2.2, type 31-A2.3 and type 31-A3. The 2 groups were compared in terms of reduction quality, rate of internal fixation failure, and function of the affected hip. Single factor and multi-factor binary logistic regression analyses were conducted to determine the risk factors responsible for failure of PFNA fixation of femoral intertrochanteric fracture.Results:There were no significant differences in the preoperative general data between the 2 groups, showing comparability between groups ( P> 0.05). Internal fixation failure occurred in 19 cases, which was caused by spiral blade withdrawal in 13 cases, femoral neck shortening in 17 cases, hip varus in 14 cases, and spiral blade cut-out in 14 cases. The failure rate for the stable group was 1.2% (5/424), significantly lower than that for the unstable group [9.7%,(14/144)] ( P<0.05). The Harris hip score at the last follow-up for the stable group [98(95,100)] was significantly higher than that for the unstable group [84 (82, 87)] ( P<0.05). There was no significant difference in reduction quality between the 2 groups ( P>0.05). The multivariate analysis showed that osteoporosis ( OR=7.283, 95% CI: 1.626 to 32.623, P=0.009) and unstable fracture ( OR=11.607, 95% CI: 4.039 to 33.355, P<0.001) were risk factors responsible for the failure of PFNA fixation of femoral intertrochanteric fracture. Conclusions:PFNA fixation for unstable intertrochanteric fracture can lead to a high failure rate. It forms a lever like structure so that the main stress is shifted to the internal fixation. Its lever fulcrum is located at the angle of intramedullary fixation so that a long arm forms at the load-bearing side, leading to a high failure rate. The weight-free time should be longer for patients with osteoporosis and unstable fracture after operation.

Therapeutic strategies for internal fixation of femoral neck fractures based on leverage fulcrum reconstruction theory / 中华骨科杂志

The objective of internal fixation is to preserve the hip and to reduce and fix the fracture. By reviewing the classifications of femoral neck fracture and the current status of internal fixation, we found that the existing internal fixation technology development cannot effectively avoid the occurrence of its related complications such as femoral neck shortening, nail withdrawal, screw removal, internal fixation fracture and so on. Multiple clinical classification methods are insufficient in guiding the selection of internal fixators. Meanwhile, the curative effects of sliding hip screw and cannulated compression screw in different fracture classifications are still controversial. Currently, there is a lack of appropriate theory to explain the occurrence of these complications and to prevent them. In this article, Based on the perspective of lever fulcrum reconstruction theory, Combined with the anatomical structure and biomechanical characteristics of proximal femur, the causes of complications related to internal fixation were revealed, and some suggestions were provided for the treatment of femoral neck fracture. The theory of lever fulcrum reconstruction explains the causes of internal fixation complications after previous treatment, and the treatment scheme recommended based on this theory has potential clinical significance, which provides a new concept for the treatment of femoral neck fracture.

Finite element analysis of biomechanical properties of bionic surface hip prosthesis / 中华骨科杂志

Objective:To compare the biomechanical properties of traditional surface hip prosthesis and bionic surface hip prosthesis.Methods:The Sawbone digital model (#3908, Left, Medium) was selected as the research object. Mimics 21.0 software was used to reconstruct the physical model of femur. Solidworks 16.0 software was used to build the model of prostheses, including the traditional and bionic (type 1-4) protheses and their assembly. The distances from the screw cross position to the top of pressure screw of type 1 to type 4 protheses were 20.22 mm, 30.12 mm, 32.17 mm and 37.76 mm, respectively. The mechanical distribution characteristics of the whole model were measured and the stress distribution cloud map was obtained.Results:The peak stresses at bone-stem junction of traditional prosthesis and type 1-4 hip prostheses were 32.18 MPa, 13.80 MPa, 15.01 MPa, 23.46 MPa and 34.51 MPa, respectively. With the fulcrums away from the top of the femur, the peak stresses at the fulcrums of type 1-4 hip protheses were 37.98 MPa, 48.60 MPa, 54.80 MPa, and 53.87 MPa, respectively. The maximum stress above femoral neck of traditional prosthesis and type 1-4 hip prostheses were 8.00 MPa, 7.80 MPa, 7.04 MPa, 7.03 MPa and 7.51 MPa, respectively. The maximum stresses under femoral neck was 15.38 MPa, 14.20 MPa, 11.11 MPa, 13.10 MPa and 12.18 MPa, respectively. The maximum stresses in the greater trochanter region of femur were 13.08 MPa, 11.61 MPa, 13.09 MPa, 11.02 MPa and 39.51 MPa, respectively.Conclusion:Compared with the traditional surface hip prosthesis, the type I bionic surface hip prosthesis is designed based on the lever balance reconstruction theory. With the bionic reconstruction of the tension trabeculae and compression trabeculae through reasonable screw placement angles and the inward movement of the fulcrum closer to the center of the femoral head, the new type prothesis make up for the design defects of the traditional surface hip prosthesis, optimize the stress distribution in the proximal femur, and improve the stability of the prosthesis after replacement, which help reduce the risk of femoral neck fracture and prosthesis loosening, and extend the service life of the prosthesis.

Expert consensus on elderly patients with hip fracture under epidemic of novel coronavirus pneumonia / 中华创伤杂志

With the spread of novel coronavirus pneumonia (NCP) in December 2019, the management and rehabilitation of elderly patients with hip fractures and protection of medical staff face new challenges, and need to be adjusted appropriately under this very circumstances. Hip fractures in the elderly account for more than half of osteoporotic fractures. Expert group formulate this consensus so as to make better decision against this epidemic and protect patients' families and medical staff. This consensus elaborates not only epidemic condition of NCP, but also general principles of medical admission, treatment and protection for both medical staff and patients, in order to provide some reference and promote the standardization of clinical diagnosis and treatment of elderly patients with hip fractures under the condition of NCP.

Advances in cell and molecular mechanisms of traumatic heterotopic ossification / 中华创伤杂志

Objective:Traumatic heterotopic ossification is the formation of extra-skeletal bone within soft tissues or joints after trauma. Injury factors induce many types of precursor cells to participate in this process. Many cytokines such as bone morphogenetic proteins, hypoxia inducible factor 1-α, inflammation factors and fibrin, can influence this process. Formation of heterotopic ossification often leads to the limitation of limb function and pain. However, prevention and treatment of heterotopic ossification often lead to bone nonunion and high recurrence rate. To find a treatment that can inhibit the formation of heterotopic ossification without affecting fracture healing has become a concern of clinicians. It is necessary to explore the formation mechanism of heterotopic ossification and find effective and safe methods. The authors document the cellular and molecular mechanisms involved in formation of traumatic heterotopic ossification for better understanding the factors affecting the formation of heterotopic ossification so as to provide references for new treatment methods.

Expert consensus on rehabilitation strategies for traumatic spinal cord injury / 中华创伤杂志

TSCI have dyskinesia and sensory disturbance that can cause various life-threaten complications. The patients with traumatic spinal cord injury (TSCI), seriously affecting the quality of life of patients. Based on the epidemiology of TSCI and domestic and foreign literatures as well as expert investigations, this expert consensus reviews the definition, injury classification, rehabilitation assessment, rehabilitation strategies and rehabilitation measures of TSCI so as to provide early standardized rehabilitation treatment methods for TSCI.

Lever-pivot balance: a neodoxy on treatment for intertrochanteric femoral fractures / 中华创伤杂志

Intertrochanteric femoral fractures are common in clinical practice and the key to treatment is timely stable fixation and early rehabilitation to prevent bedridden complications. At present, the failure of common internal fixation system in the treatment of unstable intertrochanteric femoral fractures is not rare. The authors think that for the normal anatomical type of leverage structure of human proximal femur, pivot can bear weight and complete multidirectional activities because its pivot is close to the center of the body. The intertrochanteric femoral fractures destroyed the trabecular structure on the tension side and pressure side. At the same time, the physiological lever of the proximal femur was destroyed. The cause for the failure of the existing internal fixation is the inability to reconstruct the physiological pivot. Based on the anatomical and biomechanical characteristics of the proximal femur, the author reviewed the previous literatures and analyzed the problems in the treatment of intertrochanteric femoral fractures, and for the first time raised the " lever-pivot balance" theory for the treatment of intertrochanteric femoral fractures. This theory opens a new way for solving the problems in treatment of intertrochanteric femoral fractures.