[Experimental study on improving stability of anchor by adding anchor].

OBJECTIVE: To explore whether anchor placement could improve holding force of anchors under the condition of osteoporosis, in order to solve the problem of clinical treatment for rotator cuff injury associated with osteoporosis. METHODS: Twenty one bone modules, which included 13 males and 8 females aged from 60 to 95 years old with an average of (77.6±10.3) years old, and were divided into three experimental groups named as group A, B and C, and 7 in each group. A single anchor was inserted in group A, two parallel anchors were screwed in group B, and a single anchor was screwed in group C, then after the anchor was pulled out, anchor was screwed back and another anchor was screwed in close to the anchor. X-ray examination was performed in all three groups to observe situation of anchor in osteoporosis module; the maximum axial pull-out force (Fmax) of the three groups was measured. RESULTS: Fmax of group A, B and C was (170.35±31.21) N, (314.47±23.47) N, and(292.74±25.36) N, respectively. Compared with group A, there were statistical difference of Fmax in group B and C(P<0.05), while no difference of Fmax between group B and C(P>0.05). CONCLUSION: In the case of loose anchors in the osteoporosis module, holding force of anchors could be improved by adding anchor, which provide a remedy for single anchor failure in clinical operation.

[Anatomical study on reconstruction of calcaneus fibula ligament].

OBJECTIVE: To measure anatomical data of calcaneofibular ligament (CFL), relevant data of CFL attachment to provide an anatomical basis for CFL reconstruction. METHODS: Twenty-seven adult ankle specimens were selected, including 11 males and 16 females, aged from 22 to 71 years old with an average of (41.6±17.2) years old;9 cases on the left side and 18 cases on the right side. The specimens reserved at least 20 cm above ankle joint and a complete foot, and exclude deformities, fractures, incomplete development and degenerative lesions. CFL was performed detailed anatomical observation, morphological parameters of CFL was measured, and coordinates of fibula side and calcaneal side of CFL in the coordinate axis were measured. The distance between fibula insertion of CFL and fibula tip, distance between calcaneal insertion of CFL and lateral calcaneal nodule, and Angle between CFL and long axis of fibula were also measured. RESULTS: In these 27 specimens, CFL cases were all single bundles and the length of CFL was (32.83 ± 8.19) mm. The center point of fibula attachment in CFL was(2.87± 1.21) mm proximal with a coefficient of variation of 42.16% and (2.08±1.34) mm anteriorly with a coefficient of variation of 64.42%. The center point of calcaneal attachment region of CFL was located on coordinate axis on the distal end (15.32±5.33) mm, with a coefficient of variation of 34.79%, and the posterior part (6.38±2.15) mm, with a coefficient of variation of 33.86%. The distance between center point of fibula attachment and fibula tip was (4.81±0.82) mm. The distance between center point of calcaneal attachment area of CFL and lateral calcaneal nodules was(17.25±3.12) mm. Angle between CFL and fibula axis is (43 ±18)° . CONCLUSION: According to anatomical studies, we could locate the fibula and calcaneal attachment of CFL by anatomical markers around ankle joint. However, the location of CFL attachment has a large variation, and the anatomical characteristics need to be considered in anatomical reconstruction.

[Anatomical measurement of root attachments of the menisci].

OBJECTIVE: To measure anatomical data of anterior and posterior root attachments of the medial and lateral menisci for reconstruction of root tears. METHODS: Thirty cadaveric knee joints of human were chosen, including 16 males and 14 females, death age ranged from 35 to 68 years old with an average age of (55.6±7.8) years old. Structure of root attachments of the menisci was dissected and observed, then areas of the attachments and the distances from the centers of the attachments of each structure to specific landmarks were measured. These landmarks were medial tibial eminence apex, lateral tibial eminence apex, the anterior edge of posterior cruciate ligament (PCL), lateral margin of cartilage of medial tibial plateau, medial margin of cartilage of lateral tibial plateau. RESULTS: The attachment of posterior root of medial meniscus: the central point was located on posterior about (11.73±3.10) mm and lateral about (2.77±0.86) mm to the medial tibial eminence apex; anterior about (2.76±0.76) mm to the anterior edge of PCL; lateral about (3.92±0.22) mm to lateral margin of cartilage of medial tibial plateau; the area of the attachment was (31.29±5.18) mm2 . The central point of attachment of anterior root of medial meniscus was located on anterior about (25.40±5.27) mm and lateral about (3.01±0.86) mm to the medial tibial eminence apex, and the attachment area was (46.18±11.60) mm2. The attachment of posterior root of lateral meniscus: the central point was located on posterior about (4.51 ±1.35) mm and medial about (1.85±0.34) mm to lateral tibial eminence apex; anterior about (6.91± 1.11) mm to the anterior edge of PCL; medial about (3.16±0.96) mm to medial margin of cartilage of lateral tibial plateau; and the area of attachment was (44.10±6.23) mm2. The central point of attachment of anterior root of lateral meniscus was located on anterior about (12.97±2.92) mm and lateral about (1.31 ±0.22) mm to the lateral tibial eminence apex, and the attachment area was (60.84±14.98) mm2. CONCLUSION: The study quantitatively describes the area of the attachments of the anterior and posterior roots of the medial and lateral menisci as well as the relationship between central points and corresponding landmarks, which could provide some anatomical reference for clinical repair of roots injury of menisci.

[A comparative study of the curative effect of proximal fibular osteotomy and single condylar replacement for the treatment of knee osteoarthritis of different severity].

OBJECTIVE: To compare the clinical effect of proximal fibular osteotomy (PFO) and single condyle replacement (UKA) in the treatment of knee osteoarthritis of different severity. METHODS: From June 2015 to September 2017, 53 patients with knee osteoarthritis were analyzed retrospectively. According to the operation mode, they were divided into PFO group (26 cases) and UKA group (27 cases) . According to Kellygren-Lawrence imaging classification standard：PFO group, 5 cases of gradeⅡ, 11 cases of grade Ⅲ, 10 cases of grade Ⅳ; UKA group, 7 cases of gradeⅡ, 9 cases of grade Ⅲ, 11 cases of grade Ⅳ. The amount of intraoperative bleeding, operation time and postoperative hospital stay were compared between the two groups. The patients were followed up regularly in the outpatient clinic before operation, 3 months after operation and 1 year after operation. The WOMAC score and the angle of tibiofemoral angle at each time point in the same group were compared, and the OMAC score and the angle of tibiofemoral angle at each time between the two groups were compared. RESULTS: Fifty-three patients were followed up for 12 to 24 (16.6±4.8) months. Compared with UKA group, PFO group had less intraoperative bleeding, shorter operative time and shorter postoperative hospital stay (P<0.05) . The scores of pain, stiffness and body function in UKA group were better than those in PFO group (P<0.05) . After 3 months and 1 year, the WOMAC index in PFO group was significantly improved (P<0.05) ; after 3 months and 1 year, the WOMAC index in UKA group was significantly better than that in PFO group (P<0.05) ; after 3 months, the WOMAC index in PFO group was significantly better than that in UKA group (P<0.05) . The tibiofemoral angle of gradeⅡand Ⅲ patients in both groups decreased gradually (P<0.05) ; the tibiofemoral angle of grade Ⅳ patients in UKA group was smaller than that of grade Ⅳ patients in PFO group (P<0.05) . CONCLUSION: Compared with UKA, PFO has the advantages of small trauma, fast recovery and low cost. The curative effect of PFO is equal to or more than UKA in the patients with gradeⅡand Ⅲ knee osteoarthritis. It is an alternative surgical method for the treatment of knee osteoarthritis.

[Effect of perioperative dexamethasone on nausea, vomiting and pain after total knee arthroplasty].

OBJECTIVE: To investigate the effect of perioperative dexamethasone on nausea, vomiting and pain after unilateral total knee arthroplasty and to evaluate its safety. METHODS: From February 2014 to June 2016, 100 patients with unilateral advanced osteoarthritis treated by total knee arthroplasty were divided into two groups: 50 patients in dexamethasone group including 27 males and 23 females, aged (72.30±7.02) years, were given intravenous drip of dexamethasone 10 mg before operation; 50 patients in saline group, including 26 males and 24 females, aged (71.30±6.08) years, were given the same amount of saline at the corresponding time. The VAS scores of pain at rest and at 45 degrees of knee flexion were recorded at 2, 4, 6, 8, 12, 24, 36 and 48 h after operation. Vomiting, antiemetic drugs and opioids were recorded at 0 to 24 h and 24 to 48 h after operation. The side effects and complications were recorded. RESULTS: All the 100 patients were followed up for an average of 14.5 months. VAS score of pain at rest in dexamethasone group was lower than that in saline group at 8, 24 and 48 h after operation (P<0.05); VAS score of dexamethasone group at 45 degrees after knee flexion was lower than that of saline group at 8 and 48 h after operation(P<0.05); VAS score of dexamethasone group at rest and 45 degrees after knee flexion was lower than that of saline group(P<0.05). The dosage of opioids and total opioids in dexamethasone group was lower than that in saline group at 0 to 24 h, 24 to 48 h after operation (P<0.05). The proportion of nausea and vomiting occurred at 0 to 24 h and 24 to 48 h after operation, and the proportion of antiemetic required at 0 to 24 h after operation had statistical significance between two groups(P<0.05). The total antiemetic dosage of dexamethasone group was less than that of saline group(P<0.05). As of the last follow-up, no complications such as infection, gastrointestinal ulcer and bleeding occurred in the two groups. CONCLUSIONS: Preoperative systemic application of dexamethasone can effectively reduce pain and nausea and vomiting after TKA without increasing postoperative complications.

[Finite element analysis of anterior ring injuries in unstable pelvic fractures treated by different methods].

OBJECTIVE: To compare the biomechanical stability of different fixation methods for anterior ring injury of unstable pelvic fractures, and to provide reference for clinical treatment. METHODS: An unstable pelvic fracture model (Tile C) with one side of the sacroiliac joint dislocation and the pubic rami fracture was constructed via three-dimensional finite element analysis. Five different fixation methods were used in the front, and the rear was fixed with sacroiliac screws. The von Mises stress and strain distributions of different combinations of fixation methods were analyzed under mimicking standing conditions. RESULTS: After being loaded with 500 N vertically, the maximum stress in the anterior fracture was 3.56 MPa in anterior pelvic external fixation (AEF) group, the total displacement and the vertical displacement of the Y axis at the sacroiliac joint and the fracture were not more than 1.5 mm. The maximum stress at fixation, the front of the fracture and sacroiliac joints in the anterior pelvic subcutaneous approach(APA) group and AEF, was significantly higher than anterior modified Stoppa approach(ASA) group, anterior pelvic Ilioinguinal approach (AIA) group, and canulated screw fixation(CSF) group. The total displacement and the vertical displacement of the Y axis at the sacroiliac joint and the fracture in APA group and AEF group were also greater than the other three groups. CONCLUSIONS: Anterior ring injury of unstable pelvic fractures can be significantly improved after the fixation of the implants in the five combined methods. However, overall biomechanical properties of ASA, AIA and CSF group are superior to APA and AEF group.

[Treatment for posterior root tear of lateral meniscus through bone tunnel suture under arthroscopy].

OBJECTIVE: To evaluate clinical effects of posterior root tear of lateral meniscus through bone tunnel suture under arthroscopy. METHODS: From January 2012 to December 2014, 23 patients with posterior root tear of lateral meniscus repaired through bone tunnel suture under arthroscopy, including 15 males and 8 females, aged from 19 to 48 years old with an average age of (25.0±4.7) years old; 10 knees on the left side and 13 knees on the right side. Complications were observed, Lysholm score before and after operation at 12 months were used to evaluate clinical results, and VAS score was applied to assess pain relief. MRI was used to check recovery outcomes of lateral meniscus injury. RESULTS: All patients were followed up from 13 to 24 months with an average of (17.0±4.3) months. No injury of vessels, nerve and incision infection occurred. Motion of knee joint of 19 patients reached normal, 4 patients manifested limited activity of knee joint at12 months after operation. Postoperative Lysholm score 88.52±6.48 at 12 months was higher than that of before operation 46.12±7.35; Postoperative VAS score 0.8±0.7 at 12 months was lower than that of before operation 4.3±1.6. CONCLUSIONS: Bone tunnel suture under arthroscopy for the treatment of posterior root tear of lateral meniscus could relieve pain, decrease postoperative complications and obtain good clinical efficacy.

[Treating intractable lateral epicondylitis by extracurricular arthroscopic operation based on pressure point].

OBJECTIVE: To evaluate clinical efficaly of intractable lateral epicondylitis by extracurricular arthroscopic operation based on pressure point. METHODS: From October 2015 to September 2017, 19 patients with intractable lateral epicondylitis were treated with extraarticylar arthroscopic operation based in pressure point. Among patients, including 7 males and 12 females, aged from 33 to 62 years old with an average of(43.16±8.12) years old, The courses of conservative treatment ranged from 7 to 41 months, with an average of(15.47±7.08) months. Postoperative complications were observed, VAS score and Mayo score before and after operation at 3 months were observed and compared. RESULTS: All patients were followed up from 6 to 26 months, with an average (17.16±5.25) months. No infection, skin necrosis and nerve injury occurred. No group weakness occurred within six months after operation. VAS score decreased from 4.42±1.17 before operation to 0.53±0.61 after operation at 3 months. Mago was improved from 62.63±7.88 before operation to 93.42±5.28 after operation at 3 months. According to Mayo score, 17 cases got excellent results, and 2 cases were good. CONCLUSIONS: Intractable lateral epicondylitis by arthroscopic extracurricular operation based on pressure point, which deal with main extracurricular root cause, could anatomical level is understand easily, field of vision is good and diseased tissue is cleaned up thoroughly, and has obvious curative effect.

[Treatment of obstinate tennis elbow by debridement and repair under elbow arthroscopy combined with small incision].

OBJECTIVE: To evaluate the effectivity and the improvement of elbow arthroscopic techniques of treating obstinate tennis elbow using debridement and repair under elbow arthroscopy combined with small incision. METHODS: From March 2014 to February 2017, 36 patients(total 36 elbows) with obstinate tennis elbow were treated consecutively using debridement and repair under elbow arthroscopy combined with small incision open, the two methods alternate. In key process, the first 18 cases [group A including 8 males and 12 females with an average age of (43.89±9.71) years old, the treatment time was(17.39±10.53) months] used direct-looking operation and arthroscopic verification, the latter 18 cases[group B including 7 males and 11 females with an averave age of (44.28±8.04) years old, the treatment time was(15.50±9.18) months] used arthroscopic operation and direct-looking verification. The arthroscopic and gross pathological findings were observed during the operation. After operation serious neurovascular complications were observed. The operation time was compared between two groups. MEPS (Mayo Elbow Performance Score) and VAS scores were recorded preoperatively and postoperatively. RESULTS: All patients were followed up for an average of (17.22±8.47) months in group A and (17.83±8.83) months in group B. There was 1 case of nerve injury without infection. VAS score was improved from preoperative 4.33±1.24 to postoperative 0.61±0.70 in group A, and from 4.50±1.47 to postoperative 0.67±0.69 in group B. MEPS of group A was improved from preoperative 62.22±7.90 to postoperative 93.06±5.18 in group A, and from preoperative 61.94±8.93 to postoperative 92.22±5.21 in group B. There were no statistical differences between two groups in MEPS and VAS score. The operation time in group B(54.06±8.43) min was less than that in group A(73.39±12.78) min. Thirty-two cases were satisfied greatly with treatment results, 3 cases satisfied, 1 case unsatisfied. The main reasons that results in dissatisfaction were nerve injury. CONCLUSIONS: Treating obstinate tennis elbow using debridement and repair under elbow arthroscopy combined with small incision have open and arthroscopic surgery advantages, with thorough therapeutic effect. The procedure is suitable to try to explore and improve the elbow arthroscopic technique.

[Biomechanical stability study on different internal fixation for acetabular fracture].

OBJECTIVE: To investigate the biomechanical stability of the acetabular fracture with three different internal fixation methods. METHODS: Sixteen both-column acetabular fracture models were randomly divided into three groups:The specimens of 16 hip joints were randomly divided into 4 groups. Among them, 1 group of complete acetabulum were used as normal control group, and the other 3 groups simulated two column fracture models and were fixed in the following methods, respectively: anterior wall with screw and posterior with plate(SP), anterior wall with plate and posterior wall with screw(PS) and both wall with plate (PP). The degree of fracture displacement and the contact characteristics of the acetabulum were recorded by continuous vertical loading. RESULTS: The mean longitudinal displacement under the load 800 N of SP, PS and PP three groups were (1.92±0.81), (2.09±1.13) and (3.44±0.75) mm, there was significant difference between SP and PP group (P=0.033). And the mean horizontal displacement of SP, PS and PP three groups were(0.63±0.33), (0.77±0.45) and (1.44±0.56) mm, there was significant difference between SP and PP group(P=0.047).Compared with normal control group in the acetabular area under the loading 800 N, the contact area of SP, PS and PP groups were increased by 6%, 9% and 27%, there was significant difference between PP and normal control group (P=0.027). Meanwhile, the mean stress of SP, PS and PP groups were increased by 4%, 29% and 39%, there was significant difference between PP and intact acetabulum group (P=0.003). CONCLUSIONS: Anterior column screw combined with posterior column plate has better biomechanical stability and contact characteristics than other two methods.

[Diagnostic value of MRI for posterior root tear of medial and lateral meniscus].

OBJECTIVE: To explore diagnostic value of MRI on posterior root tear of medial and lateral meniscus. METHODS: From January 2012 to January 2016, clinical data of 43 patients with meniscal posterior root tear confirmed by arthroscopy were retrospective analyzed, including 25 males and 18 females, aged from 27 to 69 years old with an average age of(42.5±8.3)years old;27 cases on the right side and 16 cases on the left side. MRI examinations of 43 patients with tear of posterior meniscus root confirmed by knee arthroscopies were retrospectively reviewed. MRI images were double-blinded, independently, retrospectively scored by two imaging physicians. Sensitivity, specificity and accuracy of MRI diagnosis of lateral and medial meniscus posterior root tear were calculated, and knee ligament injury and meniscal dislocation were calculated. RESULTS: Forty-three of 143 patients were diagnosed with meniscus posterior root tears by arthroscopy, including 19 patients with lateral tears and 24 patients with medial tears. The sensitivity, specificity and accuracy in diagnosis of posterior medial meniscus root tears for doctor A were 91.67%, 86.6% and 83.9% respectively, and for doctor B were 87.5%, 87.4% and 87.4%, 19 patients with medial meniscal protrusion and 2 patients with anterior cruciate ligament tear. The sensitivity, specificity and accuracy in diagnosis of posterior lateral meniscus root tears for doctor A were 73.7%, 79.9% and 79% respectively, and for doctor B were 78.9%, 82.3% and 82.5%, 4 patients with lateral meniscus herniation and 16 patients with cruciate ligament tear. Kappa statistics for posterior medial meniscus root tears and posterior lateral meniscus root tears were 0.84 and 0.72. CONCLUSIONS: MRI could effectively demonstrate imaging features of medial and lateral meniscal root tear and its accompanying signs. It could provide the basis for preoperative diagnosis of clinicians, and be worthy to be popularized.

Femoral tunnel positioning using an anteromedial technique for ACL reconstruction: A radiographic study with a cadaveric model.

BACKGROUND: We studied the anatomic positioning of the femoral tunnel during simulated anterior cruciate ligament reconstruction using an anteromedial portal approach in cadaveric models. METHODS: In thirty cadaveric human knee specimens, simulation of an arthroscopic anterior cruciate ligament reconstruction was performed and the femoral tunnel was drilled using an anteromedial portal. A Kirschner wire was passed into the tunnel and radiographs were obtained. These radiographs were then evaluated in the coronal and sagittal planes. Angles between the axis of the femoral tunnel and the joint line in the coronal plane (alpha, α) or the femoral long axis in the sagittal plane (beta, ß) were calculated for each specimen. The external aperture of the femoral tunnel was defined as the point of exit of the Kirschner wire from the lateral femoral cortex. This was evaluated relative to a prescribed rectangle and coordinate axis, with the radiographic quadrant method of Bernard, to assess the accuracy of femoral tunnel placement. RESULTS: The mean α in the coronal plane was 48.53∘, the mean ß in the sagittal plane was 32.23∘. All of the femoral tunnel external apertures were located outside of the rectangleCONCLUSION: We evaluated the positioning of the femoral tunnel and the external aperture of the femoral tunnel with the anteromedial portal technique. This study provides a reference standard to assess accurately femoral tunnel positioning on postoperative radiographs.

[Effects of tranexamic acid combined with temporary drain clamping on postoperative blood loss in total knee arthroplasty].

OBJECTIVE: To evaluate the efficacy and safety of one dose tranexamic acid combined with temporary drain lamping in primary unilateral total knee arthroplasty. METHODS: Total 160 patients undergoing unilateral primary total knee arthroplasty between January 2012 and December 2013 were randomly divided into four groups(40 cases in each group):group A (the drain was clamped for 2 hours after the operation and the patients received 20 ml physiological saline), group B(the drain was clamped for 2 hours after the operation and the patients received 10 ml tranexamic acid and 10 ml physiological saline), group C (the drain was clamped for 4 hours after the operation and the patients received 20 ml physiological saline) and group D(the drain was clamped for 4 hours after the operation and the patients received 10 ml tranexamic acid and 10 ml physiological saline). The postoperative hemoglobin level, maximum hemoglobin loss, wound drainage, blood loss, the volume of blood transfusion, the number of patients inquiring blood transfusion, venous thrombo embolism rate, and ecchymosis rate were recorded and compared among the four groups. RESULTS: There was no incision infection, severe hypoxia, and symptomatic pulmonary embolism in these groups. There were significant differences in hemoglobin content one day after operation in each group(F=12.26, P=0.000), in the hemoglobin content 7 days after operation in each group(F=20.74, P=0.000), in postoperative drainage in each group(F=38.71, P=0.000);in the amount of invisible red blood cell loss in each group(F=83.41, P=0.000), and in total red blood cell loss in each group(F=102.68, P=0.000). Color Doppler ultrasound examination found that the total incidence of VTE was 3%(5/160) and there were no significant differences in each group(P=0.892). There were no significant differences in postoperative subcutaneous ecchymosis area>1% incidence(P=0.143). CONCLUSIONS: Topical tranexami acid treatment combined with temporary clamping of drain for 4 hours could reduce postoperative blood loss, blood transfusion, and ecchymosis rate without increasing the risk of thromboembolic event after total knee arthroplasty.

[Femoral tunnel positioning in posterior cruciate ligament double-bundle reconstruction by computer aided design].

OBJECTIVE: To study mechanical affect of knee joint of reasonable positioning of femoral tunnel during knee posterior cruciate ligament (PCL) double-bundle reconstruction and graft fixation after reconstruction by virtual reality interactive technology and evaluate the biomechanical response of knee after reconstruction by finite element analysis. METHODS: Knee specimens from five fresh frozen cadavers were used. Computer simulations and biomechanical experiments were used in this study. Experiments on flexion and extension movements of the knee joint were performed on specimens of fresh human knee joint. Laser three dimensional scanning was used to record and calculate the indexes of movements. Three-dimensional models of knee joint bone structure were then reconstructed on computer with the experimental data. Simulations of flexion and extension movements were carried out on the models to show the spatial positions of femur and tibia and label the attachment sites of PCL. Ten test points in the anterior,posterior, proximal, distal at the femoral attachment area of anterior and lateral bundle (ALB) and postoperior medial bundle (PMB) were selected and the central points of tibial en attachment areat anchored. The distance btween each two points of two article surface was calculated and contacted by software of Geomagic. Model was import software Ansys, adopting the tetrahedron unit a finite element model of complex tibial and femoral was set up to simulat human walking in one leg,on this condition the the joint surface force of model under weight impact load were analyzed. RESULTS: The three-dimensional models could demonstrate the spatial positions of the bone structure of the knee in different flexions and extensions. The models could be used to measure the spatial distance between 2 points on the femoral and tibial planes by software Geomagic. There was significantly difference among the length changes of anterolateral bundle and posteromedial bundle at every fixed point with different flexion angles (P<0.05), so the fixed angle with different points. The length changes of anterior lateral bundle's A2, A1 and posterior medial bundle's B3, B1 points were (1.35±0.19) mm, (5.41±1.22) mm, (1.95±0.04) mm and (5.23±2.21) mm, respectively. The A2 and B3 points' length changes were the less, and that of the Al and B1 points were the more. It had no significant difference between the length changes of anterior lanteral bundle's A2 and A3 point (P=0.913>0.05). All of the maximal length changes of anterior lateral bundle's A2, A3 and postterior medial bundle's B3 points were less than 2 mm. CONCLUSION: The models of knee joint were builded through computer technology and it can be measure the lenth of cruciate ligament with software Geomagic exactly. The femoral tunnel for the PCL double-bundle reconstruction should be located as follows: ALB at the middle point of upper edge of femoral attachment site (proximal point),while PMB at the middle point of femoral attachment site (proximal point). This model provides a satisfactory method for the evaluation of the biomechanical response of knee after cruciate ligament reconstruction.

[Three-dimensional finite element analysis on mechanical behavior of the bone remodeling and bone integration between the bone-implant interface after hip replacement].

OBJECTIVE: 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. METHODS: :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. RESULTS: 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. CONCLUSION: 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.

[Suture anchor for acute injuries of medial collateral ligament of knee at degree III].

OBJECTIVE: To evaluate clinical efficacy of suture anchors in treating acute injuries of medial collateral ligament (MCL) of knee at degree III. METHODS: Twenty-seven patients with degree III acute MCL injuries of knee were treated with suture anchors from January 2007 to June 2011. There were 15 males and 12 females, aged from 19 to 56 (averaged 32.6) years old. The time from injury to operation was 3 to 10 days, averaged 6 days. Symptoms and physical signs before and after treatment were observed, Lysholm scoring were used to evluated clinical efficacy. RESULTS: All patients were followed up from 16 to 30 months with an average of 21.6 months. The stability of knee joints was good in all patients. Abduction stress test was negative when the knee joint was straightened at 0 degrees and flexed at 30 degrees. The average degree of flexed knee (67.00 +/- 5.80) degrees preoperatively was lower than that of postoperatively (136.50 +/- 6.30) degrees at 1 year. According to Lysholm scoring, preoperative scores ranged from 30 to 43 points, averaged 36.46 +/- 1.48; 1 year after operation ranged from 87 to 100 with an average of 91.50 +/- 3.80 and higher than postoperative. Twenty patients got an excellent results, 5 good and 2 fair. CONCLUSION: Suture anchors in treating acute injuries of medial collateral ligament of knee at degree III has following advantages: small range of tissue dissection, easy to operate, reliable fixation and less complications.

[Clinical apprehension on application of Tri-lock BPS total hip arthroplasty].

OBJECTIVE: To study short-term results and clinical application of Tri-lock BPS in total hip arthoplasty. METHODS: From May 2010 to July 2011, 32 hips in 31 patients (18 males and 13 females, ranging in age from 50 to 77 years old, with an average of 60.5 years old) were treated by total hip arthroplasty with Tri-lock BPS, including 8 patients with osteonecrosis (ON), 13 patients with fresh femoral neck fracture, 10 patients with developmental dysplasia of the hip (DDH). The therapeutic effects were evaluated by self assessment form, preoperative and postoperative Harris hip score, radiographs, Engh score and bone in growth of femoral side described by Gruen. Based on the short-term results,its design characteristic and clinical properties were analyzed. RESULTS: All the incisions healed well and there were no complications such as femoral fracture, infection, dislocation and neurovascular injuries. All the patients were followed up with an average time of 12.2 months (ranged, 10 to 14 months). All the joints had good or excellent clinical results. The Harris score increased from preoperative 38.3 +/- 4.9 to 92.5 +/- 11.2 at the latest follow-up (t = 27.53, P < 0.01). Radiographically, the positions of the prostheses were normal,the average limbs length and femoral eccentricity recovered to normal. X-ray of the hips showed that the femoral stem prosthesis was in line with good initial fixed standard. At 3 months after surgery, X-ray of the hips showed that bone in growth in Gruen II and VI of femoral side. CONCLUSION: Short-term results show that the design of Tri-lock BPS is more in line with human anatomy, and has the advantages in rapid recovery of hip function and retains more bone mass. It offers a newly valuable technology for the treatment of osteonecrosis, femoral neck fracture and DDH and so on.

[Arthroscopic single bundle anterior cruciate ligament anatomical reconstruction with remnant preservation].

OBJECTIVE: To investigate the feasibility and clinical effects of single bundle anterior cruciate ligament anatomical reconstruction with remnant preservation. METHODS: From October 2007 to November 2009, 17 patients (10 male and 7 female, ranging in age from 28 to 62 years, with an average of 39.3 years) with posterior cruciate ligament injuries were treated with single bundle anatomical reconstruction with remnant preservation. Nine patients had the injuries caused by traffic accident; 6 patients caused by falling down; and 2 patients caused by sports injuries. The average time from injury to surgery was 8.5 days (ranging from 2 to 14 days). The international knee documentation committee knee evaluation form (IKDC) and Lysholm were used to analysis the effect of surgery. RESULTS: All the patients obtained the follow-up and the average time was 29.5 months (ranging from 24 to 39 months). There were no complications such as injuries of popliteal fossa artery, tibial nerves or peroneal nerve. Twelve patients had knee joint recovering to normal; 1 patient had stiff joints and was treated with arthroscopic surgery to release after 6 months,who had postoperative flexion lack of 20 degree and straight to normal. Three patients had flexion loss of 5 to 10 degree, and 1 patient had hyperextension limitation of 5 degree. Posterior drawer test in 17 patients and the Lachman test were negative. IKDC scores of the 17 patients achieved normal(16 patients) or near normal(1 patient). IKDC overall score normal in 16 patients (94.1%), close to normal in 1 case (5.9%). The IKDC subjective score was 94.3+/-5.1 and Lysholm score was 94.7+/-3.1 at the latest follow-up. CONCLUSION: The single bundle anterior cruciate ligament with remnant preservation anatomical reconstruction can provide good clinical results.

[Anatomical study on the femoral tunnel anatomy reconstruction of anterior cruciate ligament].

OBJECTIVE: To measure anatomical data of the femoral tunnel anatomy reconstruction of anterior cruciate ligament (ACL), so provide anatomical basis for clinical anatomy reconstruction of ACL. METHODS: There were 30 adults' cadaveric knee specimens. The ACL femoral tunnel was reconstructed through anterior medial approach (AMP) in genuflex position of 120 degree, and was marked by Kirschner. The soft tissue of the specimen was removed and the femoral condyle was split at the middle side. The index including length of the femoral tunnel, the distance from internal opening of tunnel to cortical edge of femoral condyle and vertical distance to the top of femoral intercondylar notch were measured. Then the time position of internal opening of tunnel in the intercondylar notch was recorded, and the location of outside opening of tunnel to the femoral condyle was detected. RESULTS: The mean length of the femoral tunnel was (36.35 +/- 3.14) mm (ranged, 30.65 to 42.35 mm). The distance from internal opening of tunnel to cortical edge of femoral condyle was (17.84 +/- 3.35) mm (ranged, 14.02 to 23.49 mm), vertical distance to the top of femoral intercondylar notch was (14.05 +/- 2.32) mm (ranged, 9.17 to 20.08 mm). According to the way of circular dial,internal opening of tunnel located at 02:30 +/- 00:10 (ranged, 01:50 to 02:50) in the left knee,and 09:30 +/- 0:15 (ranged, 08:30 to 10:40) in the right knee. The outside opening of femoral tunnel located at (3.16 +/- 2.51) mm (ranged, 1.61 to 6.30 mm) to the proximal end of external epicondyle of femur, and (4.25 +/- 2.16) mm (ranged, 1.73 to 8.52 mm) to the posterior of external epicondyle of femur. CONCLUSION: The anatomical features of femoral tunnel for reconstruction of ACL is revealed,which will provide anatomical basis for clinical practice.