Biomechanical study on the treatment of intertrochanteric fracture of A3.3 type with medial sustainable nail and proximal femoral anti-rotation nail / 中国骨伤

OBJECTIVE@#A3 intertrochanteric fracture is an extremely unstable fracture, which is often treated with intramedullary nail, but the implant failure is common due to the posterior medial fragment cannot be reconstructed. A new medial sustainable nail (MSN-Ⅱ) which can reconstruct the femoral medial support by sustainable screw was introduced in this study. The mechanical effect was verified by biomechanical experiment.@*METHODS@#The loss medial support model of intertrochanteric fracture (A3) was made by artificial Sawbones model, fixed with MSN-Ⅱ and PFNA-Ⅱ, underwent axial loading and axial failure tests. The axial stiffness, yield load, displacement of head-neck fragment and torsional angle of fracture site of these nails were recorded and compared for biomechanical differences. The effect of early reconstruction of medial support with MSN-Ⅱ was determined.@*RESULTS@#The axial stiffness, yield load, the displacement of head and neck fragment when the axial load was 1 800 N and torsional angle of the fracture site after the axial failure test of MSN-Ⅱ were (222.76 ±62.46) N /mm, (4 241.71 ±847.42) N, (11.51 ±0.62) mm, (1.71 ±0.10)° respectively, while the PFNA -Ⅱ was (184.58±40.59) N /mm, (3 058.76±379.63) N, (16.15±1.36) mm, (2.52±0.26)°respectively. The difference between the two groups was statistically significant.@*CONCLUSION@#The axial stiffness of MSN-Ⅱ is better than that of PFNA-Ⅱ. The MSN-Ⅱ can bear more loads when fixed A3.3 intertrochanteric fracture and has greater axial and rotational stability. It is an effective means to reconstruct the medial support of A3 intertrochanteric fracture.

Medial support nail and proximal femoral nail antirotation in the treatment of reverse obliquity inter-trochanteric fractures (Arbeitsgemeinschaft fur Osteosynthesfrogen/Orthopedic Trauma Association 31-A3.1): a finite-element analysis / 中华医学杂志(英文版)

BACKGROUND@#The reverse obliquity inter-trochanteric fracture is a distinct fracture pattern that is mechanically different from most inter-trochanteric fractures and the optional treatment of it is still controversial. The purpose of this study was to compare differences in the efficacy of a novel nail (medial support nail [MSN-II]) and proximal femoral nail anti-rotation (PFNA-II) in the treatment of reverse obliquity inter-trochanteric fractures (Arbeitsgemeinschaft fur Osteosynthesfrogen/Orthopedic Trauma Association [AO/OTA] 31-A3.1) using finite-element analysis.@*METHODS@#Modeling software was used to establish a three-dimensional model of MSN-II and PFNA-II and an A3.1 inter-trochanteric fracture model. Abaqus software was used to implement different force loads to compare finite-element biomechanical parameters such as the maximum stress in implant and the displacement of fracture site.@*RESULTS@#The femoral stress, implant stress and fracture site displacement of MSN-II was less than that of PFNA-II. The results indicated that the maximal femoral stress was 581 MPa for PFNA-II and 443 MPa for the MSN-II. The maximum stress values in the PFNA-II and MSN-II models were 291 and 241 MPa, respectively. The maximal displacements of the fracture site were 1.47 and 1.16 mm in the PFNA-II and MSN-II models, respectively.@*CONCLUSION@#Compared with PFNA-II for inter-trochanteric fracture (AO/OTA 31-A3.1), MSN-II which was designed with a triangular stability structure can provide better biomechanical stability. The MSN-II may be a feasible option for the treatment of reverse obliquity inter-trochanteric fracture.

Three-dimensional mapping of intertrochanteric fracture lines / 中华医学杂志(英文版)

BACKGROUND@#Available research about the anatomic patterns of intertrochanteric fractures is lacking, and fracture mapping has not previously been performed on intertrochanteric fractures. This study aimed to determine the major trajectories of intertrochanteric fracture lines using computed tomography data from a series of surgically treated patients.@*METHODS@#In this study, 504 patients with intertrochanteric fractures were retrospectively analyzed. Fracture patterns were graded according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Fracture lines were transcribed onto proximal femoral templates and graphically superimposed to create a compilation of fracture maps that were subsequently divided into anterior, posterior, lateral, and medial fracture maps to create a three-dimensional (3D) pattern by reducing fragments in the 3D models. The fracture maps were then converted into frequency spectra. The major fracture patterns were assessed by focusing on the lateral femoral wall, lesser trochanter, intertrochanteric crest, and inner cortical buttress.@*RESULTS@#Anterior, posterior, lateral, and medial fracture maps were created. The majority of fracture lines (85.9%, 433/504) on the anterior maps were along the intertrochanteric line where the iliofemoral ligament was attached. In the medial plane, the majority of fracture lines (49.0%, 247/504) shown on the frequency spectrum included the turning point involving the third quadrant. In the posterior plane, the majority of fracture lines (52.0%, 262/504) involved the intertrochanteric crest from the greater to the lesser trochanter. In the lateral plane, the majority of fracture lines (62.7%, 316/504) involved the greater trochanter at the gluteus medius attachment.@*CONCLUSIONS@#The fracture patterns observed in the present study might be used to describe morphologic characteristics and aid with management strategies. Further classifications or modifications that incorporate the fracture patterns identified in this study may be used in future research.

Three-dimensional mapping of intertrochanteric fracture lines / 中华医学杂志(英文版)

Background@#Available research about the anatomic patterns of intertrochanteric fractures is lacking, and fracture mapping has not previously been performed on intertrochanteric fractures. This study aimed to determine the major trajectories of intertrochanteric fracture lines using computed tomography data from a series of surgically treated patients.@*Methods@#In this study, 504 patients with intertrochanteric fractures were retrospectively analyzed. Fracture patterns were graded according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification. Fracture lines were transcribed onto proximal femoral templates and graphically superimposed to create a compilation of fracture maps that were subsequently divided into anterior, posterior, lateral, and medial fracture maps to create a three-dimensional (3D) pattern by reducing fragments in the 3D models. The fracture maps were then converted into frequency spectra. The major fracture patterns were assessed by focusing on the lateral femoral wall, lesser trochanter, intertrochanteric crest, and inner cortical buttress.@*Results@#Anterior, posterior, lateral, and medial fracture maps were created. The majority of fracture lines (85.9%, 433/504) on the anterior maps were along the intertrochanteric line where the iliofemoral ligament was attached. In the medial plane, the majority of fracture lines (49.0%, 247/504) shown on the frequency spectrum included the turning point involving the third quadrant. In the posterior plane, the majority of fracture lines (52.0%, 262/504) involved the intertrochanteric crest from the greater to the lesser trochanter. In the lateral plane, the majority of fracture lines (62.7%, 316/504) involved the greater trochanter at the gluteus medius attachment.@*Conclusions@#The fracture patterns observed in the present study might be used to describe morphologic characteristics and aid with management strategies. Further classifications or modifications that incorporate the fracture patterns identified in this study may be used in future research.

Mid-term effect of unilateral pedicle screw fixation and transforaminal lumbar interbody fusion in the treatment of lumbar degenerative diseases / 中国骨伤

<p><b>OBJECTIVE</b>To investigate the feasibility and the mid-term effects of unilateral pedicle screw fixation and transforaminal lumbar interbody fusion in treating lumbar degenerative diseases.</p><p><b>METHODS</b>From August 2005 to May 2010, 56 patients with lumbar degenerative diseases underwent lumbar posterolateral fusion,their clinical data were retrospective analyzed. The patients were divided into two groups (unilateral group and bilateral group) according to fixation methods,27 patients in unilateral group who were underwent unilateral pedicle screw fixation, including 18 males and 9 females with a mean age of (57.5 ± 7.1) years old (ranged from 41 to 66 years); and 29 patients in bilateral group who were treated with bilateral pedicle screw fixation (on the basis of the above, with contralateral vertebral pedicle screw fixation), including 19 males and 10 females with a mean age of (54.6 ± 5.1) years old (ranged from 43 to 68 years). The clinical data such as operation time, blood loss volume, hospitalization time and cost were compared between two groups. JOA score system was used to evaluate the neurological function. And fusion status and cage-related complication were also analyzed.</p><p><b>RESULTS</b>All patients were followed up from 36 to 60 months with an average of 45.8 months. No iatrogenic nerve, blood vessels or organs injury were found during operation. Operation time, blood loss volume, hospitalization time and cost in unilateral group were better than that of bilateral group (P < 0.05). There was no significant difference in JOA score between two groups (P > 0.05). Two patients in unilateral group developed with cage related complications, 1 case was cage displacement and 1 case was cage subsidence, while 2 patients in bilateral group developed with complications of no-fusion, and there was no significant differences between two groups (P = 0.58).</p><p><b>CONCLUSION</b>Unilateral pedicle screw fixation is a satisfactory method and can obtain good effects in treating lumbar degenerative diseases in mid-term, however, the indications should be well considered.</p>

Three-dimensional finite element analysis on mechanical behavior of the bone remodeling and bone integration between the bone-implant interface after hip replacement / 中国骨伤

<p><b>OBJECTIVE</b>To discuss the primary stability of the fixed interface between the cementless prosthesis and femur, and its influence on bone ingrowth and secondary stability under the roughened surface and press fit of different prostheses by finite element analysis.</p><p><b>METHODS</b>:A three-dimensional finite element module of total hip arthroplasty (THA) was developed with Mimics software. There was a collection of data when simulating hip arthroplasty. The frictional coefficient between the fixed interface was 0,0.15,0.40 and 1.00 representing the roughness of prosthesis surface. The press fit was 0, 0.01,0.05 and 0.10 mm according to the operation. The Vion Mises stress distribution and the contact pressure,friction stress and relative sliding displacement between the interface were analysed and compared when simulating the maneuver of climbing stairs.</p><p><b>RESULTS</b>At a fixed press fit of 0.05 mm,the contact pressure between the interface was 230 , 231, 222 and 275 MN under four different frictional coefficient (0,0. 15,0.40 and 1.00) with little change; the relative sliding displacement was 0.529, 0.129, 0.107 and 0.087 mm with a consistent and obvious decline. As the fixed frictional coefficient was 0.40,the contact pressure between the interface were 56.0,67.7 ,60.4 and 49.6 MN under four different press fit (0, 0.01, 0.05 and 0.10 mm) with a reduction; the relative sliding displacement was 0.064,0.062,0.043 and 0.042 mm with an obvious decline, and there was a maximal friction stress when press fit of 0.01 mm.</p><p><b>CONCLUSION</b>There is a dynamic process of the bone remodeling and bone integration between the interface after hip replacement, determining the long-term outcome. The interface clearance and the frictional coefficient are the key factors of the bone integration.</p>

Effects of recombinant human osteoprotegerin and recombinant RANK protein on the differentiation of osteoclast precursors / 中国骨伤

<p><b>OBJECTIVE</b>To compare the effect of recombinant OPG-Fc and recombinant RANK protein on the differentiation of osteoclast precursors.</p><p><b>METHODS</b>Mouse osteoblasts cell lines were incubated with osteoclast precursors cell lines RAW 264.7 for 9 days with 10(-5) g/L rhRANK or rhOPG-Fc or PBS added to the coculture system. TRAP stain positive cells counting and cortical bone pit formation counting were performed in the 9th day.</p><p><b>RESULTS</b>Multinuleated TRAP stain positive cells were observed in the cocluture systems after 6 days incubation,and plenty of mature osteoclasts could be observed in the 9th day. With the addition of 10(-5) g/L rhOPG-Fc or rhRANK, multinucleated giant cells and cortical bone pit formation couting decreased significantly compared with the control group, and the rhRANK group decreased more significantly than the rhOPG-Fc group.</p><p><b>CONCLUSIONS</b>Both rhOPG-Fc and rhRANK can inhabit the differentiation of osteoclast precursors and prevent them forming mature osteoclasts,moreover,the rhRANK shows the significant inhabition effect than the rhOPG-Fc.</p>

Inhibitory effect of recombinant receptor activator of nuclear factor kappaB protein on bone loss in ovariectomized mice / 中国骨伤

<p><b>OBJECTIVE</b>To compare inhibitory effects of recombinant receptor activator of nuclear factor kappaB protein with bisphosphonate treatment (ALN) on osteoclasts activity and bone loss in ovariectomized mice.</p><p><b>METHODS</b>Twenty-four female KM mice were ovariectomized bilaterally and treated with recombinant receptor activator of nuclear factor kappaB protein, alendronate, or PBS. Twelve weeks later, body weight, biochemical markers of bone metabolism, Micro CT scan and bone morphology were examined.</p><p><b>RESULTS</b>After 12 weeks administration, the Micro CT scan and bone morphology values of each group were as follow. The control group: BMD (92.600 +/- 14.319) mg/cc, Tb.Th (0.094 +/- 0.011) mm, Tb.Sp (0.455 +/- 0.124) mm, BVF 0.192 +/- 0.023, SMI 1.388 +/- 0.328; the recombinant receptor activator of nuclear factor kappaB protein group: BMD (133.050 +/- 13.022) mg/cc, Tb.Th (0.098 +/- 0.009) mm, Tb.Sp (0.365 +/- 0.105) mm,BVF (0.291 +/- 0.025)%, SMI 0.661 +/- 0.384; the ALN group: BMD(128.013 +/- 16.040) mg/cc, Tb.Th (0.097 +/- 0.011) mm, Tb.Sp (0.376 +/- 0.104) mm, BVF 0.281 +/- 0.024, SMI 0.753 +/- 0.307. In the ovariectomized mice experiments, both recombinant receptor activator of nuclear factor kappaB protein and ALN significantly inhibited ovariectomy-induced bone loss. Compared to the control group (PBS), the recombinant receptor activator of nuclear factor kappaB protein group showed increased distal femur BMD and decreased trabecular spacing (Tb.Sp), whereas the control group had significantly decreased distal femur BMD, significantly decreased Tb.Th, and increased Tb.Sp. There was a significant difference in bone volume fraction among the groups. The TRAP-positive osteoclasts in distal femur bone slices were nearly complete inhibited for Recombinant receptor activator of nuclear factor kappaB protein group and alendronate group.</p><p><b>CONCLUSION</b>In vivo, recombinant receptor activator of nuclear factor kappaB protein effectively inhibits the activity of osteoclasts and the resulting bone loss, which has a similar effect as alendronate.</p>

Biological changes after axonal stretch and their mechanisms / 中国医学科学院学报

Research on peripheral nervous injuries, especially the stretched injuries, is important to improve the clinical effectiveness and alleviate the patients's pain. In recent years, the biological changes and mechanics of stretched axons have been hot topics. This article reviews the recent advances in the morphological changes of axons as well as changes in cellular membrane, cytoskeleton, cellular metabolism, and action potential after axonal stretch.

Finite element analysis on a modified cannulated screw for fixation of femoral neck fracture / 医用生物力学

Objective To establish the three-dimensional finite element model of the cannulated screws for fixing the femoral neck fracture, and investigate stress distributions on three cannulated screws as well as determine whether internal fixation by a modified cannulated screw can provide sufficient stiffness and strength for the fixation. Methods The 3D finite element model was internal-fixed at the angle of 127°with femoral shaft under the inverted triangle mode to simulate loading on single legged standing condition. Stresses on three screws (No 1: the underneath screw, No 2: the anterosuperior screw, No 3: the posterosuperior screw) were calculated at different Pauwels angle (50°, 60°, 70°, 80°), respectively. A bore was drilled in the screw with the largest stress to study the effect of bore size and bore direction on the femoral neck fracture model with screw fixation. Results The stresses of three screws increased with the Pauwels angle increasing and reached the maximum value at 80°. The maximum stresses on No.1, No.2 and No.3 screw were 304, 515 and 154 MPa, respectively. When the No 2 screw had an opening bore with 1 mm in diameter, and the direction of the bore was not between 150°and 195°, the stresses on three screws were all within the safe limits. Conclusions From the mechanical point of view, three screws are subject to different stresses. The cannulated screws with side bore have good biomechanical properties for fixing the femoral neck fracture with safety and reliability, which can provide advantages for accelerating fracture healing by injecting drugs through the central and side bore into the fracture side.

Surgical selection and efficacy assessment for membranous urethral trauma caused by pelvic fracture / 中国骨伤

<p><b>OBJECTIVE</b>To explore selection and efficacy assessment for membranous urethral trauma caused by pelvic fracture.</p><p><b>METHODS</b>From June 2000 to August 2010, 72 patients with membranous urethral trauma caused by pelvic fracture were selected. There were 46 males and 26 females,ranging age from 26 to 62 years (averaged 35.2 years). The time from injury to hospitalization time was 1 to 3 hours. According to Tile pelvic fracture classification, there were 8 patients with type A, 45 patients with type B, 19 patients with type C. Thirty of the 35 patients with partial rupture of posterior urethral were treated by catheterization,5 patients treated by rupture anastomosis on the stage I combined with cystostomy; 25 of the 37 patients with complete rupture of posterior urethra were treated by early realignment, and 12 patients were treated by cystostomy. Urinary incontinence, impotence and urethrostenosis were evaluated.</p><p><b>RESULTS</b>All patients were followed up for 5 to 10 years (mean 7.7 years). Incidence of urethrostenosis, impotence and urinary incontinence in patients treated by cystostomy were significantly higher than rupture anastomosis on the stage I and early realignment (P < 0.05); while incidence in patients treated by catheterization was significantly lower than other groups (P < 0.05).</p><p><b>CONCLUSION</b>For patients with partial rupture of posterior urethral, catheterization and rupture anastomosis on the stage I are preferred methods; while patients with complete rupture of posterior urethra, early realignment is a preferred method with advantages of simple operation and less complications.</p>

The cup safe-zone and optimum combination of the acetabular and femoral anteversions that fulfills the desired range of motion of the hip / 中国骨伤

<p><b>OBJECTIVE</b>To investigate safe range of acetabular prosthesis angle and the optimum combination of cup and neck in the range of activities of daily living (ADL).</p><p><b>METHODS</b>A three-dimensional generic parametric and kinematic simulation module of THA was developed. Range of motion (ROM) of flexion > or = 110 degrees, internal-rotation > or = 30 degrees at 90 degrees flexion, extension > or = 30 degrees and external rotation > or = 40 degrees were defined as the normal criteria for desired ROM for activities of daily living (ADL), and ROM of flexion > or = 120 degrees, internal-rotation > or = 45 degrees at 90 degrees flexion, extension > or = 30 degrees and external rotation > or = 40 degrees as the severe criteria. The range of the changes in the general head-neck ratios (GR), the femoral neck anteversion (FA), the operative anteversion (OA) and operative inclination (OI) of the cup component were 2-2.92, 0 degrees-30 degrees, 0 degrees-70 degrees, 10 degrees-60 degrees respectively. For the collodiaphyseal angle (CCD) of 135 degrees, the corresponding OA related to the OI which every 5 degrees was calculated, and described using dots and lines in a coordinate system in which OI of acetabular cup was the horizontal ordinate and OA of acetabular cup was the vertical ordinate. All data was analyzed by SAS 6.12 software.</p><p><b>RESULTS</b>Large GR greatly increased the size of safe range and it was recommended that GR be more than 2.37 when the CCD-angle was 135 degrees as it further increases the size of safezone. The size of cup safety range of the severe criteria was smaller than normal criteria. When the CCD-angle was 135 degrees, the optimum relationship between OA of acetabular and FA of the normal criteria and the severe criteria can be estimated by the formula: Y1=-0.816X1 + 39.76 (R2=0.993), Y2=-0.873X2 + 47.04 (R2=0.999) respectively.</p><p><b>CONCLUSION</b>Large GR greatly increases the size of safe-zone and it is recommended that GR be more than 2.37, so it extends the acceptable range of error that clinicians cannot avoid it completely. The larger range of the hip motion, the smaller size of the cup safe-zone,but can retrieve by increase the GR. The OA is negative with FA.</p>

Case-control study on the relationship between pain and knee function after the internal fixation of femoral fractures / 中国骨伤

<p><b>OBJECTIVE</b>To investigate the relationship between pain and knee function after the internal fixation of femoral fractures.</p><p><b>METHODS</b>The clinical data of 73 patients after internal fixation on femoral fractures from June 2006 to December 2009 were retrospectively analyzed. All the patients were divided into two groups according to the degree of postoperative pain: low score group and high score group. Among the 39 patients in low score group (VAS 1 to 5 point), 25 patients were male and 14 patients were female, with a mean age of (37.5 +/- 5.3) years (ranged from 27 to 63 years ). Among 34 patients in high score group (VAS 6 to 10 point), 22 patients were male and 12 patients were female, with a mean age of (36.3 +/- 9.6) years (ranged from 29 to 62 years). The intra-articular pressure of knee and hospital for special surgery knee rating scale (HSS) were recorded and analyzed.</p><p><b>RESULTS</b>All the patients were followed up for an average duration of 24.1 months. The intra-articular pressure of knee was rising for two groups, there were significant difference for the high score group compared with the low score group at 3 days after operation (t=15.67, P=0.000) and the end time of follow up (t=5.63, P=0.000). As to knee joint function, in low score group, 21 patients got an excellent result, 4 good, 7 poor and 2 bad; in high score group, 31 patients got an excellent result, 6 good, 2 poor and no bad. The knee function of low score group was better than that of high score group.</p><p><b>CONCLUSION</b>The intra-articular pressure of knee is an important factor of the knee functional recovery, and its external symptoms of pain can be seen as an important index to forecast the prognosins of knee function in early time.</p>

Effects of femoral tunnel placement on the isometry of grafts in PLC reconstruction / 医用生物力学

Objective To explore the influence of femoral tunnel placement on the isometry of grafts in the reconstruction of posterolateral corner of the knee (PLC). Method Knee specimens from 9 frozen human cadavers were used in the study. Five points of femoral attachment sites, including the central, proximal, distal, anterior and posterior points, were selected as femoral test points for both lateral collateral ligament（LCL）and popliteus tendon（PT）. The fibular/tibial attachment sites of LCL, PT and popliteofibular ligament（PFL） were connected to the corresponding 5 test points using the brass wire, respectively. Changes in distance between each pair of fibular/tibial and femoral points were measured during the passive knee flexion extension test (0°~90°). Results The maximal changes of distances between the LCL’s anterior, distal points and LCL’s fibular attachment site were not greater than 3 mm, and there was no significant difference between these two points; the maximal change of distance between the PT’s anterior point and PFL’s fibular attachment site were not greater than 3 mm. All of the maximal changes of distances between the PT’s 5 test points and tibial point of musculotendionous junction were greater than 3 mm. Conclusions Under the condition of fibular tunnels locating at center points of LCL and PFL attachment site, the femoral tunnel should be located at the anterior edge of LCL’s attachment site (anterior point) for LCL reconstruction, and at the anterior edge of PT’s attachment site (anterior point) for PFL reconstruction.

The significance of intraoperative computed tomograph scan for complex acetabular fractures / 中华骨科杂志

ObjectiveTo investigate the application of intraoperative Computed Tomograph (CT) using in surgery for complex acetabular fractures.MethodsFrom June 2008 to December 2010,14 patients (9 males,5 females; with the mean age of 45.1 years; range,28-62 years) with complex acetabular fractures were operated using intraoperative CT.Preoperative radiotherapy and CT scan were adopted to evaluate the fractures.Three dimensional reconstruction based on CT scan was used to mimic surgery.The surgery approach and the type of internal fixators were noted.Intraoperative C-arm and CT scan were used to evaluate the fractures reduction respectively.Decision of additional reduction was made by surgeons according to above mentioned methods respectively and the results were noted.Comparing to preoperative design,the change of surgery plan were noted.Overall time,frequency and radiation dose of intraoperative CT scan were also noted.ResultsAll patients in this study received average 2.7 times of intraoperative CT scan.Mean time of CT scan was 40.4 min and the overall dose of radiation was 47.2 mGy.Decision of additional reduction was made in 3 cases according to C-arm radiography and 4 cases according to CT scan (above mentioned 3 cases were included).The change of surgery plan was made in one case.In postoperative radiography evaluation according to Matta's score system,anatomical reduction were achieved in 8 cases,imperfect reduction in 3 cases and poor reduction in 3 cases.ConclusionIntraoperative CT scan increases the radiation time and dose of patients dramatically.When used to evaluate fracture reduction intraoperatively,it can't take the advantage of traditional C-arm radiography.When delicate preoperative plan is made with radiography and three dimensional reconstruction based on CT data,the efficiency of intraoperative CT scan for complex acetabular fractures are to be discussed.

Clinical application of "funnel technique" in planting thoracic pedicle screws / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the safety and accuracy of "funnel technique" in planting thoracic pedicle screws.</p><p><b>METHODS</b>From August 2005 to March 2008, a total of 39 patients with at least one thoracic pedicle screw in T1-T10 using "funnel technique" were retrospectively reviewed. Among the patients, 27 patients were male and 14 patients were female, with a mean age of 38.5 years (ranged from 17 to 56 years). One patient was lost follow-up, and other 1 patient was dead before follow-up. The accuracy of screw placement and the complications related to thoracic pedicle screws were analyzed by postoperative CT-scans.</p><p><b>RESULTS</b>All the patients were followed up ranging from 18 to 30 months, averaged 23.2 months. There were no vascular or viscera complications as well as iatrogenic neurologic injuries. The total number of screws was 208. There was no statistical difference between the percentage of fully contained screws at T1-T4 versus T5-T8 (P = 0.80),T5-T8 versus T9-T10 (P = 0.07), T1-T4 versus T9-T10 (P = 0.06). Twenty-seven screws (13.0%) were misplaced, 14 screws (6.7%) violated lateral cortex of pedicle, 7 screws (3.4%) medially, 5 screws (2.4%) superiorly, 1 screw (0.5%) violated lateral cortex of vertebral body. No violations occurred superiorly or anteriorly. Only 4 screws (1.9%) was a critical perforation.</p><p><b>CONCLUSION</b>The "funnel technique" is a simple, safe, accurate and cost-effective technique for pedicle screw placement. It provides even an entry-level surgeon with a safe way to identify and place thoracic pedicle screws.</p>

Influences of head/neck ratio and femoral antetorsion on the safe-zone of operative acetabular orientations in total hip arthroplasty / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To study the influences of head/neck ratio and femoral antetorsion on the safe-zone of operative acetabular orientations, which meets the criteria for desired range of motion (ROM) for activities of daily living in total hip arthroplasty (THA).</p><p><b>METHODS</b>A three-dimensional generic, parametric and kinematic simulation module of THA was developed to analyze the cup safe-zone and the optimum combination of cup and neck antetorsion. A ROM of flexion > or =120 degree internal rotation > or = 45 degree at 90 degree flexion, extension > or = 30 degree and external rotation > or =40 degree was defined as the criteria for desired ROM for activities of daily living. The cup safe-zone was defined as the area that fulfills all the criteria of desired ROM before the neck impinged on the liner of the cup. For a fixed stem-neck (CCD)-angle of 130 degree theoretical safe-zones fulfilling the desired ROM were investigated at different general head-neck ratios (GR=2, 2.17, 2.37, 2.61 and 2.92) and femoral anteversions (FA equal to 0 degree,10 degree,20 degree and 30 degree).</p><p><b>RESULTS</b>Large GRs greatly increased the size of safe-zones and when the CCD-angle was 130 degree, a GR larger than 2.37 could further increase the size of safe-zones. There was a complex interplay between the orientation angles of the femoral and acetabular components. When the CCD-angle was 130 degree the optimum relationship between operative acetabular anteversion (OA) and femoral antetorsion (FA) could be estimated by the formula: OA equal to -0.80 multiply FA+47.06, and the minimum allowable operative acetabular inclination (OI(min)) would be more than 210.5 multiply GR(-2.255).</p><p><b>CONCLUSIONS</b>Large GRs greatly increase the size of safe-zones and it is recommended that the GR be more than 2.37 so as to extend the acceptable range of error that surgeons cannot avoid completely during operation. As to the optimum operative acetabular inclination (OI), surgeons need to make a decision combining with other factors, including stress distribution, soft tissue and cup wear conditions, as well as patients'individual situations and demands. The data obtained from this study and the module of THA can be used to assist surgeons to choose and implant appropriate implants.</p>

Biomechanical compatibility of osteoporotic vertebral augmentation with cancellous bone granules and bone cement: a finite element evaluation / 医用生物力学

Objective The goal of this study was to investigate the biomechanical compatibility effects of cancellous bone granule(CBG) augmentation of Optimesh and polymethylmethacrylate (PMMA) augmentation of Kyphoplasty on treated andadjacent non-treated vertebral bodies. Methods Three-dimensional, anatomically detailed finite element (FE) models of the L1–L2functional spinal unit (FSU) were developed on the basis of cadaver computed tomography (CT) scans. The material properties and plug forms of the L2 centrum were adapted to simulate osteoporosis, CBG and PMMA augmentation. The models assumed a three-column loading configuration as the following types: compression, flexion and extension. Results Compared with the osteoporotic model, changes in stress and strain at adjacent levels both of CBG and PMMA augmentation models were minimal, but stresses/strains within the two reinforcement material plugs were modified distinctly and differently. In addition, osteoporosis, CBG and PMMA augmentation had little effect on either the axial compressive displacement of the three columns or the average disc internal pressure in all models. Conclusion Both morcelized cancellous bone and PMMA augmentation restore the total strength and stiffness level of treated vertebral bodies and benefit the reconstruction of vertebral function. Regarding the biomechanical compatibility and the biocompatibility of the treated vertebral body and reinforcement material, however, the morcelized cancellous bone is better than PMMA augmentation.

Influence of positioning of the femoral tunnel for MPFL reconstruction on the isometric characteristics of grafts / 医用生物力学

Objective To explore the influence of positioning of the femoral tunnel for medial patellofemoral ligamentre (MPFL)construction on the isometric characteristics of grafts.Method Knee specimens from ten fresh frozen cadavers were used. The attachment of medial patellofemoral ligament was observed. The distance between points from the adductor tubercle, the medial femoral epicondyle, and proximal, distal and central point of the MPFL’s femoral attachment site respectively to the middle point of its patellar attachment site were measured. Changes in length were recorded while the knee was measured by angles of knee flexion (0°, 30°, 60°, 90°, and 120°). Results The length changes in every point were compared. All of the maximal length changes of its adductor tubercle: proximal points were not greater than 3 mm. There was no significant difference between the length changes of adductor tubercle and proximal points（P>0.05）. Conclusions The position of the femoral turnel for MPFL reconstruction should be located as follows: MPFL should be at the middle point of upper edge of femoral attachment site (proximal point), and the point can appropriately be shifted to adductor tubercle.

Clinical apprehension on application of metal on metal total hip arthroplasty with large diameter heads / 中国骨伤

<p><b>OBJECTIVE</b>To approach the short-term result and clinical application of metal on metal total hip arthroplasty with large diameter heads and evaluate its safety and efficacy clinically.</p><p><b>METHODS</b>From January 2007 to March 2008, 39 hips in 37 patients (24 males and 13 females,ranging in age from 43 to 75 years, with an average of 58.5 years) were treated with metal on metal total hip arthroplasty with large diameter heads (ASRTM XL) included 14 cases of osteonecrosis (ON), 2 cases of osteoarthritis (OA), 18 cases of fresh femoral neck fracture, 3 cases of developmental dysplasia of the hip (DDH). All patients were evaluated by self assessment form, hip function examination, radiographs, preoperative and postoperative Harris hip score. Based on the short-term results, its design characteristic and clinical properties were analyzed.</p><p><b>RESULTS</b>All the incision healed well and there were not any complications such as femoral fracture, infection, dislocation and neurovascular injury. All patients obtained the follow-up and an average time was 16.5 months (12 to 19 months), all the joints had good or excellent clinical results. Radiographically, the positions of the prostheses were normal, the average limbs length and femoral eccentricity recovered as normal. The average range of motion of the hip improved remarkable, such as flexion improved from (20.1 +/- 8.2) degrees to (85.7 +/- 9.8) (t = 32.86, P < 0.01), abduction improved from (10.2 +/- 4.4) degrees to (41.5 +/- 9.1) degrees (t = 19.34, P < 0.01), adduction improved from (16.3 +/- 8.8) degrees to (40.3 +/- 10.4) (t = 11.00, P < 0.01),external rotation improved from (12.3 +/- 5.2)0 to (42.0 +/- 7.7) degrees (t = 19.96, P < 0.01), internal rotation improved from (3.4 +/- 1.1) degrees to (23.0 +/- 9.8) degrees (t = 12.41, P < 0.01). The Harris score rose from preoperative (39.3 +/- 5.6) to (91.4 +/- 10.3) at the latest follow up (t = 27.75, P < 0.01).</p><p><b>CONCLUSION</b>Short-term results show that metal on metal hip joint prosthesis with large diameter heads has advantages of small deformation of acetabular cup, lower wearing, large range of motion and few dislocation. It offers a newly valuable technology for treatment of osteonecrosis, osteoarthritis, femoral neck fracture and DDH with the higher requirement of movement after the operation.</p>