Internal fixator vs external fixator in the management of unstable pelvic ring injuries:A prospective comparative cohort study

BACKGROUND Reconstruction of the pelvic ring anatomy in unstable anterior pelvic ring injuries is a significant step to reduce the mortality rate associated with these injuries efficiently.There is a debate on using either an anterior subcutaneous pelvis internal fixator(INFIX)or an anterior supra-acetabular external fixator(EXFIX)to manage an unstable anterior pelvic ring fracture.AIM To compare the functional and radiological outcomes and complications of INFIX vs EXFIX in managing unstable pelvic ring injuries.METHODS A prospective cohort study included 54 patients with unstable pelvic ring fractures.The patients were divided into two groups;the INFIX group,in which 30 cases were fixed by INFIX,and the EXFIX group,in which 24 patients were treated by EXFIX.The average age in the EXFIX group was 31.17 years(16-57 years),while in the INFIX group,it was 34.5 years(17-53 years).The study included 20(66.7%)males and 10(33.3%)females in the INFIX group and 10(41.7%)males and 14(58.3%)females in the EXFIX group.The radiological outcomes were evaluated using Matta and Tornetta's score,and the functional outcomes using the Majeed score.RESULTS The results revealed a statistically significant difference between both groups(P=0.013)regarding radiological outcomes,according to Matta and Tornetta's score in favor of the INFIX group.Sitting,standing,and walking abilities were measured at a 3-mo follow-up visit using Majeed score modules.It was significantly better among the INFIX group than the EXFIX group in all three modules.At the final follow-up,both groups had no statistically significant difference according to the Majeed score;92.35 in the INFIX group and 90.99 in the EXFIX group(P=0.513).A lower surgical site infection rate was noticed in the INFIX group(P=0.007).CONCLUSION Anterior subcutaneous pelvis INFIX is associated with better radiological outcomes and a lower infection rate than anterior supra-acetabular EXFIX in managing patients with unstable anterior pelvic ring fractures.

Dynamic External Fixator Combined with Volar Locking Plate Fixation for the Treatment of AO Type C3 Distal Radius Fractures

Background: AO type C3 distal radius fracture (DRF) is the most difficult-to-treat fracture type because of a tendency to shorten and collapse. The purpose of this study is to investigate the clinical and radiographic outcomes of comminuted intra-articular DRFs treated with a dynamic external fixator combined with a volar locking plate (VLP). Methods: Eleven patients (mean age, 61 years) with comminuted intra-articular DRFs were treated with a dynamic type of external fixator combined with a VLP. Following reduction and fixation with a VLP, the dynamic external fixator was applied and the distal ball joint of the fixator was aligned with the lunate-capitate line. The ball joint was unlocked approximately 2 weeks after surgery to allow wrist mobilization. The fixator was removed 3 - 6 weeks (mean, 5 weeks) after surgery. Consequently, clinical and radiographic assessments were carried out at the final follow-up. Results: At the final follow-up, the mean range values of wrist extension and flexion were 76°and 64°, respectively. Compared with the contralateral side, the mean grip strength was 84%. The mean Modified Mayo Wrist Score and the Disabilities of the Arm, Shoulder and Hand score were 88 and 9, respectively. No significant differences in the radiographic parameters exist between after surgery and final follow-up. Conclusions: This study indicated that the dynamic wrist fixator combined with a VLP is effective for the treatment of AO type C3 DRFs.

Proximal tibial osteotomy for genu varum:Radiological evaluation of deformity correction with a plate vs external fixator

BACKGROUND High tibial osteotomy(HTO)is a well-known procedure for the correction of knee varus.The purpose of this study was to compare the radiological results and accuracy of deformity correction performed using two different techniques:acute opening wedge correction using a plate and gradual correction with a monolateral external fixator.AIM To compare of the radiological results of two different techniques:acute opening wedge correction(a plate and screw)and gradual correction(external fixator).METHODS A total of 43 patients with plates and 36 patients with external fixators were included.All patients had moderate uniplanar varus deformities.We measured radiographic parameters,including the mechanical axis deviation(MAD),medial proximal tibial angle(MPTA),Caton-Deschamps Index(CDI),posterior proximal tibial angle,and joint line obliquity angle(JLOA).The accuracy of MAD correction was calculated based on a correction goal of neutral or overcorrection for medial compartment arthritis.RESULTS Demographics including age,body mass index,sex,and preoperative deformities were similar between the groups.The MAD significantly improved from 23.6 mm medial to the midline(SD=8.2 mm)to 6.9 mm lateral to the midline(SD=5.4 mm)(P<0.001).The accuracy of MAD correction did not differ between the groups and was 96.1%(SD=8.1%)in the plate group and 98.2%(SD=5.2%)in the external fixator group(P=0.18).The MPTA significantly improved from 83.9°(SD=2.9°)to 90.9°(SD=3.3°)(P<0.001),and the change was similar between the groups.Differences were noted in patella height,with a CDI change of-19.2%(SD=13.7%)and 3.1%(SD=8.0%)for the plate and external fixator groups,respectively(P<0.001).The change in JLOA was 1.6 degrees(SD=1.1 degrees)and 0.9 degrees(SD=0.9 degrees)for the plate and external fixator groups,respectively(P=0.04).CONCLUSION Reliable correction of moderate varus alignment was achieved with both the acute opening wedge technique with a plate and the gradual monolateral external fixator technique.The patellar height decreased with the open wedge plate technique.Joint line obliquity decreased to a greater degree with the open wedge plate technique,perhaps as a result of medial collateral ligament release.The appropriate technique should be selected based on surgeon and patient preferences;however,external fixation may be a better choice when the preservation of patellar height is deemed important.

HYBRID EXTERNAL FIXATOR FOR THE TREATMENT OF UNICAMERAL BONE CYSTS WITH PATHOLOGICAL FRACTURE IN THE PROXIMAL HUMERUS

Objective: Unicameral bone cyst is a nonneoplasticbone lesion characterized by its tenacity and risk ofrecurrence. Pathological fracture is common and is often the presenting symptom. The objective of the present study was to evaluate the results of hybrid external fixator for thetreatment of a unicameral bone cyst with a pathologicalfracture. Methods: Hybrid external fixator for thetreatment of a unicameral bone cyst was performed intwelve patients. These patients presented with a pathological fracture and were managed immediately with hybridexternal fixator, of whom four had been managedconservatively at other clinics before they were referred toour department. The cyst was located in the proximalhumerus in all patients. The mean age of the patients at the time of surgery was 8.7 years, and the mean duration offollow-up was 32.6 months. Radiographic evaluation wasperformed according to the criteria of Capanna et al., andthe cyst was classified as completely healed, healed withresidual radiolucency (osteolysis), recurred, or having noresponse. Results: The healing period ranged from three to eight months. Eight cysts healed completely, and threehealed with residual radiolucent areas visible onradiographs. There was recurrence of one cyst that hadhealed with residual radiolucency. All of the cysts in thepresent study responded to treatment. A modulation ofhybrid external fixator was necessary in three patients, asthe bars had become too short after bone growth or the pins had been loose. No major complications were observed.Conclusion: Hybrid external fixator provides earlystability, which allows early mobilization and thus obviates the need for a plaster cast. This method of treatment alsoallows for an early return to normal activity.

A BIOMECHANICAL ANALYSIS OF UNILATERAL HOOKED-SULCATED EXTERNAL FIXATOR ON OSTEOMINED TIBIA

Four tibiae removed from 30-40 years males, who died of accidents in less than 12 hours, were os- teomized at medium part. Then these tibiae were fixed by an unilateral hooked-sulcated external fixator (UHSEF), and the bone-fixator system was used as a model of external fixation of tibial fracture. The axial compression, distraction, torsion, antero-posterior and lateral bending rigidly and the strain of the pins were determined in this system. Based on the results, we found that compared with the configuration of four paralled pins, the rigidity of the fan-like configuraton didn’t decrease significantly if the angle between lateral and medium pins was less than 45’. But the reverse was true when the frame separation increased from 5 to 8 cm. What’ more, the pin strain decreased if the rigidity of the system was improved. These data provided a theoretical basis of biomechanics for the improvement of UHSEF.

Stress Analysis of the Sarafix External Fixator Design

A stress analysis of the Sarafix external fixator design was performed using finite element analysis （FEA） and experimental tensometric measurements. The study was conducted at one of the Sarafix fixator configurations that have a clinical application in the treatment of tibia fractures. The intensity of principal and yon Mises stresses generated at two measuring points （MP） on the fixator connecting rod were monitored and analyzed during the testing on axial compression on the fixator design and its finite element model （FEM）. The 3D geometrical and FEM model of the fixator was formed using the computer aided design/computer aided engineering （CAD/CAE） software system CATIA. Verification of the results for the dominant principal stresses obtained from FEA was carried out through tensometric measurements. The measuring chain consisted of strain gauges connected into two Wheatstone half-bridges, digital measuring amplifier system and a computer with software for acquisition and monitoring of measurement results. A quite good agreement was observed between the results obtained on the basis of FEA and results of experimental tensometric analysis,

External fixator with lumbopelvic distraction spondylodesis for vertically unstable pelvic fracture

Objective To evaluate the clinical outcomes of external fixator with lumbopelvic distraction spondylodesis in treatment of vertically unstable pelvic fractures.Methods From January 2008 to March 2009,9 patients(4 males and 5 females)

Dynamic external fixator combined with limited internal fixation for Pilon reactures

Objective To evaluate effects of manipulative reduction,dynamic external fixator combined with limited internal fixation for the treatment of Pilon fractures.Methods From January 2007 to June 2009,manipulative reduction,dynamic external

Ilizarov external fixators for maluninon of obsolete calcaneal fracture of Stephen Type Ⅲ

Objective To evaluate the clinical effects of Ilizarov external fixator for maluninon of obsolete calcaneal fracture of Stephen Type Ⅲ.Methods From July 2006 to February 2009,25 patients suffering from maluninon of obsolete calcaneal

An experimental study of a novel external fixator based on universal joints for the rapid initial stabilization of mandibular comminuted fractures

Purpose:Shaping and assembling contemporary external fixators rapidly for the severe mandibular fractures remains a challenge,especially in emergency circumstance.We designed a novel external fixator that incorporates universal joints to provide the stabilization for mandibular comminuted fractures.This study aims to confirm the efficacy of this novel external fixator through biomechanical tests in vitro and animal experiments.Methods:In vitro biomechanical tests were conducted using 6 fresh canine with mandibular defect to simulate critical comminuted fractures.Three mandibles were stabilized by the novel external fixator and other mandibles were fixed by 2.5 mm reconstruction plates.All fixed mandibles were subjected to loads of 350 N on the anterior regions of teeth and 550 N on the first molar of the unaffected side.The stability was evaluated based on the maximum displacement and the slope of the load-displacement curve.In animal experiments,9 beagles with comminuted mandibular fractures were divided into 3 groups,which were treated with the novel external fixation,reconstruction plate,and dental arch bar,respectively.The general observation,the changes in animals’weight,and the surgical duration were recorded and compared among 3 groups.The CT scans were performed at various intervals of 0 day(immediately after the surgery),3 days,7 days,14 days,21 days,and 28 days to analyze the displacement of feature points on the canine mandible and situation of fracture healing at 28 days.The statistical significance was assessed by the two-way analysis of variance test followed by the Bonferroni test,enabling multiple comparisons for all tests using GraphPad Prism10.1.0(GraphPad Inc,USA).Results:The outcomes of the biomechanical tests indicated that no statistically significant differences were found in terms of the maximum displacement(p=0.496,0.079)and the slope of load displacement curves(p=0.374,0.349)under 2 load modes between the external and internal fixation groups.The animal experiment data showed that there were minor displacements of feature points between the external and internal fixation groups without statistic difference,while the arch bar group demonstrated inferior stability.The CT analysis revealed that the best fracture healing happened in the internal fixation group,followed by the external fixation and arch baring at 28 days after fixation.The external fixation group had the shortest fixation duration(25.67±3.79)min compared to internal fixation((70.67±4.51)min,p<0.001)and arch baring((42.00±3.00)min,p=0.046).Conclusion:The conclusion of this study highlighted the efficacy and reliability of this novel external fixator in managing mandibular fractures rapidly,offering a viable option for the initial stabilization of comminuted mandibular fractures in the setting of emergency rescue.

Treatment of type C3 distal radius fracture resulted from high-energy injuries by volar plate in combination with external fixator

Background With a type C3 distal radius fracture it is extremely difficult to maintain the reduction and to restore congruity of the articular surface because the support for the volar and dorsal bone cortex has been lost. An external fixator crossing wrist in combination with Kirschner wire （K-wire） fixation was popularly used by most studies in recent years. But loss of reduction often occurred especially in the volar sides. Methods A total of 30 cases of type C3 distal radius fracture were treated by a volar buttress plate combined with a transarticular external fixator and other techniques such as K-wire fixation and bone grafting if necessary. The postoperative volar tilt angles, ulnar inclinations, radial heights, range of motion, grip strength and complications were recorded to assess the therapeutic effects. Results Of the 30 patients, 27 patients were followed up for 12-29 （mean 18） months and all fractures healed in 8-13 weeks after surgery （mean 10 weeks）. The wrist function was excellent in 8 cases, good in 16 cases and fair in 3 cases according to the Sarmiento scoring system （modified by Stewart）. Conclusions For type C3 comminuted fracture with severe volar and dorsal instability, fixation by volar buttress plate combined with transarticular external fixator should be adopted. Dorsal instability could be further stabilized by other techniques such as Kirschner wire fixation, and bone grafting.

Management of intra-articular fracture of the fingers via mini external fixator combined with limited internal fixation

Background Intra-articular fractures of the fingers are common problems to emergency physicians and hand surgeons Inappropriate management of these injuries may result in chronic pain, stiffness, deformity, or post traumatic arthritis. Ideal treatment necessitates the restoration of a stable and congruent joint that will allow early mobilization. The purpose of this study was to investigate the results of intra-articular fracture of the fingers by mini external fixator combined with limited internal fixation. Methods From May 2005 to May 2007, a total of 26 patients with intra-articular fracture of the fingers were treated by mini external fixator combined with limited internal fixation. Of the 26 cases, 11 involved in metacarpophalangeal joint, and 15 interphalangeal joint in proximal interphalangeal. Kirschner wire, mini wire and absorbable suture were used for limited internal fixation. All patients were followed up and patients were accomplished with total active motion （TAM） of fingers. Results All patients were reviewed by an independent observer. The mean follow up was 13 months （range 9 to 24 months）. Subjective, objective and radiographic results were evaluated. X-ray films revealed fracture union and the average radiographic union time was 7 weeks with a range of 5-12 weeks and the phalange shortening or rotation in 2 cases, joint incongruity （less than 1 mm） and joint space narrowing in 3 cases respectively. Phalangeal shortening or rotation was observed in 2 cases and joint incongruity or joint space narrowing was observed in 3 cases. An artificial implant was performed on one case for traumatic arthritis 1.5 years after surgery. Based on TAM the overall good-excellent rate of joint motion function was 80.8%. Conclusion Mini external fixator combined with limited internal fixation is a reliable and effective method for treatment of intra-articular fracture of the fingers.

Unilateral external fixator in the treatment of lower third humeral shaft fractures

Objective: To retrospectively analyze the effect of unilateral external fixators in the treatment of lower third humeral shaft fractures.Methods: From October 1997 to October 2003, 33 patients aged 15 -70 years (average 31 years) with lower third humeral shaft fractures were treated with unilateral external fixators. There were 9 spiral fractures (type A1), 1 oblique fracture (type A2), 3 transverses fractures (type A3) and 20 comminuted fractures (11 type B1, 9 type B2) according to AO classification. Fifteen cases were treated with open reduction and limited internal fixation and fixation with external fixators, 10 cases treated with open reduction and fixation with external fixators, and 8 cases treated with closed reduction and fixation with external fixators. Nerve exploration was undertaken in 9 cases with preoperative radial nerve injury. External fixators were removed after bone healing. The average follow-up was 18 months with a range from 8 to 24 months. Results: The time of bone healing ranged 11-22 weeks (average 14 weeks). The latest follow-up showed the functions of 9 cases of preoperative radial nerve injury and of 2 cases postoperative radial nerve injury and the function of elbow were recovered to normal. There were only 7 cases of superficial infection at pin hole, which was subsided by using oral antibiotics and pin-hole care with mild disinfectants.Conclusions: Fixation with unilateral external fixators combined with open reduction and limited internal fixation has a good effect in the treatment of lower third humeral shaft fractures.

Closed reduction external fixator fixation versus open reduction internal fixation in the patients with Bennett fracture dislocation

Background The Bennett fracture is either a common or a challenging problem to hand surgeons.It is still debated whether closed or open reduction gives optimal results.This study aimed to describe and assess a closed reduction and mini-external fixator fixation technique for the treatment of Bennett＇s fracture dislocation and to compare this technique versus open reduction and internal fixation.Methods From October 2002 to December 2012,56 patients with Bennett＇s fracture dislocation were treated by closed reduction and mini-external fixator fixation and 32 patients were treated by open reduction and internal fixation in Jishuitan Hospital.Patients with an articular step-off of more than 1 mm were excluded.All patients were assessed at a mean followup of 7 years （range 2-10 years） and the two groups were compared with pain levels,active range of trapeziometacarpal motion,grip strength and pinch strength,arthritic changes,and adduction deformity.Results Based on primary closed reduction maintained,the rate of anatomic reduction is 63.6％.Radiographic fracture union was achieved in all patients at a mean time of 5 weeks.At the final follow-up,there was no difference between the two groups in mean union time and pain levels （P=-0.2）.There was also no difference between the two groups regarding the active range of trapeziometacarpal motion （P=0.3）,grip stength （P=0.6）,pinch strength （P=0.2）,arthritic change and loss of reduction （P=0.2）.There was a significant correlation between adduction deformity and the development of arthritis （P=0.02）.Conclusion Closed reduction mini-external fixator fixation should be first tried to apply in the treatment of Bennett＇s fracture dislocation,and open reduction internal fixation should only be performed for irreducible fractures.

Dynamic condylar screw or hip joint （spanning） external fixator for treatment of pathological fractures of femoral neck and trochanter secondary to benign lesions

The treatment of pathological fractures of the femoral neck and trochanteric region secondary to benignlesions can be a challenge for orthopaedic surgeons because of the size and nature of the lesions, the resulting bony defect, the risk of recurrence, the possible associated deformities, and the risk of osteonecrosis. Numerous treatment modalities have been reported for the management of pathological fractures of the proximal femur secondary to benign lesions. An unsatisfactory outcome in 25% of patients and a complication rate of 45% have been observed.

A comparative study of variable angle volar plate and bridging external fixator with K-wire augmentation in comminuted distal radius fractures

Purpose:Comminuted intraarticular distal radial fractures are difficult to treat conservatively and require operative treatment.This study compared the functional outcomes between variable angle volar plating and external fixator with K-wire augmentation in open reduction and internal fixation.Methods:A total of 62 adult patients with comminuted intraarticular distal radius fracture were randomized into 2 groups:volar plate group and external fixator group.These patients aged between 18 and 60 years had unilateral fractures,and agreed to be included in the study.Patients with a history of fracture,bilateral fracture,associated other injuries,delayed injury for more than 2 weeks,open fracture,pre-existing arthrosis or disability,psychiatric illness and pathological fracture were excluded.Patients were followed up at 6 weeks,3 months,6 months and 1 year.The assessment of pain,functional activity,range of motion and grip strength was done at each stage of follow-up.The pain and functional activities were assessed by patient rated wrist evaluation(PRWE)score and disabilities of the arm,shoulder and hand(DASH)score.Results:Patients in volar plate group had superior PRWE score and DASH score at each stage of followup.At 1 year follow-up,the mean PRWE score were 7.48 for volar plate group and 7.35 for external fixator group;while the mean DASH score was 4.65 for volar plate group and 5.61 for external fixator group.They had better flexion and extension range of movement.They also had better pronation and supination range of motion at initial follow-up,however the difference get attenuated by 1 year.Volar plate group had significantly better grip strength than external fixator group.Complication rates were higher in external fixation group.Conclusion:Fixation with variable angle volar plate results in early wrist mobilization,better range of movement,less pain and disability and early return of function.

Treatment of tibial defect and bone nonunion with limb shortening with external fixator and reconstituted bone xenograft

Objective: To explore the effect of external fixator and reconstituted bone xenograft (RBX) in the treatment of tibial bone defect, tibial bone nonunion and congenital pseudarthrosis of the tibia with limb shortening. Methods: Twenty patients ( 13 males and 7 females) with tibial bone defect, tibial bone nonunion or congenital pseudarthrosis of the tibia with limb shortening were treated with external fixation. Two kinds of external fixators were used: a half ring sulcated external fixator used in 13 patients and a combined external fixator in 7 patients. Foot-drop was corrected at the same time with external fixation in 4 patients. The shortened length of the tibia was in the range of 2-9 cm, with an average of 4.8 cm. For bone grafting, RBX was used in 12 patients, autogenous ilium was used in 3 patients and autogenous fibula was implanted as a bone plug into the medullary canal in 1 case, and no bone graft was used in 4 patients. Results: All the 20 patients were followed-up for 8 months to 7 years, averaging 51 months. Satisfactory function of the affected extremities was obtained. All the shortened extremities were lengthened to the expected length. For all the lengthening area and the fracture sites, bone union was obtained at the last. The average healing time of 12 patients treated with RBX was 4.8 months. Conclusions: Both the half ring sulcated external fixator and the combined external fixator have the advantages of small trauma, simple operation, elastic fixation without stress shielding and non-limitation from local soft tissue conditions, and there is satisfactory functional recovery of affected extremities in the treatment of tibial bone defects, tibial bone nonunion and congenital pseudarthrosis of the tibia combined with limb shortening. RBX has good biocompatibility and does not cause immunological rejections. It can also be safely used in treatment of bone nonunion and has reliable effect to promote bone healing.

Coupled external fixator and skin flap transposition for treatment of exposed and nonunion bone

Objective： To discuss the effect of coupled external fixator and skin flap transposition on exposed and nonunion bones.Methods： The data of 12 cases of infected nonunion and exposed bone following open fracture treated in our hospital during the period of March 1998 to June 2008 were analysed. There were 10 male patients, 2 female patients,whose age were between 19-52 years and averaged 28 years.There were 10 tibial fractures and 2 femoral fractures. The course of diseases lasted for 12-39 months with the mean period of 19 months. All the cases were treated by the coupled external fixator and skin flap transposition.Results： Primary healing were achieved in 10 cases and delayed healing in 2 cases in whom the tibia was exposed due to soft tissue defect and hence local flap transposition was performed. All the 12 cases had bony union within 6-12 months afer operation with the average time of 8 months. They were followed up for 1-3 years and all fractures healed up with good function and no infection recurrence.Conclusion： The coupled external fixator and skin flap transposition therapy have shown optimal effects on treating infected, exposed and nonunion bones.

Biomechanical analysis of fracture fixation with external fixator in vivo

Objective ：To investigate the different ways of measuring the main axial strain during treatment with an external fixator and to find the suitable compression loaded by the external fixator at an early stage. Methods. Eighteen healthy big-ear rabbits were randomly divided into two groups according to different measuring methods： Group A and Group B. In Group A, a strain gauge was affixed to the external tibiai cortex with 502 glue, and in Group B, a bone cement-coated strain gauge was installed on the internal tibial cortex. Groups A and B were divided into two subgroups A1, A2 and B1, B2, respectively, according to the pressure of haft of and the same as the body weight. A Z-shaped left mid-shaft tibiai osteotomy was performed and fixed by an external fixator. Results： The scaler curves of Group A changed dramatically during the early stage. The trendlines of the internal and external cortex went consistently after reaching the stable stage while the latter strain value was higher than the former. The time for Group B reaching the stable stage was short, but its absolute strain value was less than that of Group A. Before they were pressed to the stable stage, the declined speed of Subgroup A1 was more slowly than that of Subgroup A2 while the results of Subgroups B1 and B2 were same. Group A had an ascending trend after it declined while Group B didn＇t have. After they reached the stable stage, both Subgroups A1 and A2 had a declining trend while Subgroup A2 was more quickly than Subgroup A1, Subgroup B1 was kept at a definite level while Subgroup B2 fluctuated. Conclusions： The axial strain under external fixator can be measured by bone cement coated-strain gauge in vivo. The data may suggest that half of the body weight load was suitable for external fixator.

Biomechanical Study on Osteotomized Tibias Fixed with Unilateral Adjustable External Fixator

Five fresh tibias removed from 30-40 years old dead males were osteotomized at one-third supra-medium segment and then fixed by an unilateral adjustable external fixator (UAEF) to be used as a model of external fixation of tibial fracture. For each loading test under different configurations of UAEF, the ratio of the force-displacement was used to determine its stiffness value. The weakest mode of the UAEF device is in AP bending. Under each mode of compression,distraction , anteroposterial and lateral bending and torsion loading , increasing the pin number or pin diameter or pin separation, and/or reduction of pin group separation can significantly increase the stiffness values of UAEF (P<0.01). These data revealed that UAEF is suitable for the external fixation of tibial fracture.