Non-locking Group Research Articles

Locked plate constructs are not necessarily stiffer than nonlocked constructs: A biomechanical investigation of locked versus nonlocked diaphyseal fixation in a human cadaveric model of nonosteoporotic and osteoporotic distal femoral fractures.

The objective of this study was to compare the biomechanical properties of locked and nonlocked diaphyseal fixation in a model of distal femur fractures using osteoporotic and nonosteoporotic human cadaveric bone. A supracondylar osteotomy was created to mimic a fracture (OTA/AO 33A3) in osteoporotic (n = 4) and nonosteoporotic (n = 5) cadaveric distal femurs. The left and right femurs of each pair were instrumented with a distal femoral locking plate and randomly assigned to have diaphyseal fixation with either locked or nonlocked screws. The construct was cyclically axially loaded, and construct stiffness and load to failure were evaluated. In osteoporotic bone, locked constructs were more stiff than nonlocked constructs (mean 143 vs. 98 N/mm when all time points combined, P < 0.001). However, in nonosteoporotic bone, locked constructs were less stiff than nonlocked constructs (mean 155 N/mm vs. 185 N/mm when all time points combined, P < 0.001). In osteoporotic bone, the average load to failure was greater in the locked group than in the nonlocked group (mean 1159 vs. 991 N, P = 0.01). In nonosteoporotic bone, the average load to failure was greater for the nonlocked group (mean 1348 N vs. 1214 N, P = 0.02). Bone mineral density was highly correlated with maximal load to failure (R2 = 0.92, P = 0.001) and stiffness (R2 = 0.78, P = 0.002) in nonlocked constructs but not in locked constructs. Contrary to popular belief, locked plating constructs are not necessarily stiffer than nonlocked constructs. In healthy nonosteoporotic bone, locked diaphyseal fixation does not provide a stiffer construct than nonlocked fixation. Bone quality has a profound influence on the stiffness of nonlocked (but not locked) constructs in distal femur fractures.

Continuous non-locking vs. interrupted suturing techniques for the repair of episiotomy or second-degree perineal tears: A single-blind randomized controlled trial.

Perineal trauma is a serious and frequent problem after childbirth which is experienced by millions of women worldwide. The technique used for perineal repair may have an impact on pain and wound healing. The aim of the present study was to compare the continuous non-locking technique with interrupted suturing for the repair of episiotomy or second-degree perineal tears. A single-blind randomized-controlled trial was conducted from October 2021 to August 2022 in Sina Hospital, Ahvaz, Iran. Three hundred women were selected and randomly assigned into control and intervention groups using block randomization technique. The main outcomes included pain and wound healing that were assessed using visual analog scale (VAS), as well as redness, edema, ecchymosis/bruising, discharge, and approximation scale (REEDA). The secondary outcomes were the use of analgesics, duration of perineal repair, material used for suturing, pain during urination and defecation, and resumption of sexual intercourse. The participants were followed up on the first and seventh days and in the 6th week postpartum. Mann-Whitney, Chi-square, and Generalized Estimating Equations (GEE) model were used for data analysis. Wound healing was significantly better in the continuous non-locking suture technique compared to the interrupted technique (β = -1.98; P > 0.0001). Women also experienced less pain in the continuous non-locking suture technique (β = -2.46; P > 0.0001). There was a reduction in the use of analgesics, the duration of perineal repair, and the material used for suturing in the continuous non-locking suturing technique as opposed to the interrupted method (P < 0.0001).The odds of pain during urination and defecation significantly reduced in women who underwent the continuous non-locking method (P < 0.001). Also, women in the continuous non-locking group resumed their sexual intercourse earlier (P < 0.0001). The findings of this study revealed that use of continuous non-locking technique for suturing was associated with reduced perineal pain and improved wound healing. Furthermore, it was associated with a shorter duration of perineal repair, less suture material used, and less need for analgesics compared with the interrupted method. There is, however, need for more studies to confirm the results of the present study.Iranian registry for randomized controlled trials (Ref. ID: IRCT20190415043283N1).

Locking versus non-locking plating system in the treatment of mandibular fractures: A randomized comparative study

To evaluate fracture stability and complications such as infections, need for hardware removal, malunion, and nonunion when using 2.0-mm locking plating system in fixation of mandible fractures and to compare these to those associated with the 2.0-mm non-locking plating system.A prospective clinical study was conducted in a cohort of mandible fracture patients who were randomly assigned to two groups. Patients in the non-locking group were treated with 2.0-mm non-locking plating system, and those in locking group were treated with 2.0-mm locking plating system. Fracture stability, need for maxillomandibular fixation (MMF) and postoperative complications were assessed and compared.A total of 60 patients (30 in each group) were recruited. Significant differences were found between the two groups with respect to postoperative fracture stability (P = 0.001) and need for MMF (P = 0.005). Multivariate analysis revealed that type of fixation was not the only dependent variable which affected fracture stability. There were no significant differences in postoperative complications between the two groups.The 2.0-mm locking plating system provides greater stability and early functional restoration than the 2.0-mm non-locking plating system, with similar rates of postoperative complications. Thus, it can be used as a reliable and effective treatment modality for treating mandibular fractures.

Locking versus Non-locking Neutralization Plates with Limited Excision and Internal Fixation for Treatment of Extra-articular Type a Distal Tibial Fractures.

Purpose:This study aimed to compare the clinical, radiologic, and cost-effectiveness results between locking and non-locking plates for the treatment of extra-articular type A distal tibial fractures.Methods:We performed a retrospective review of AO/OTA 42-A1, A2 distal tibial fractures treated by plates from January 2011 to June 2013. Patients were divided to the locking plate group or the non-locking plate group. Clinical outcomes, radiographic outcomes, and hospitalization fee were compared between the two plates groups.Results:28 patients were treated with a locking plate and 23 patients were treated with a non-locking plate. The mean follow-up was 18.8 months (12-23 months). There were no significant differences between the groups in surgical time, bleeding, bone union time, or AOFAS scores. The cost of the locking plate was ¥24,648.41 ± 6,812.95 and the cost of the non-locking plate was ¥11,642 ± 3,162.57, p < 0.001. Each group had one patient that experienced superficial infection these wounds were readily healed by oral antibiotics and dressing changes. To date, five patients in the locking group and ten patients in the non-locking group had sensations of metal stimulation or other discomfort (X2 = 3.99, p < 0.05) Until the last follow-up, 14 patients in the locking plate group and 18 patients in the non-locking plate group had their plates removed or wanted to remove their plates (X2 = 4.31, p < 0.05).Conclusion:The use of locking or non-locking plates provides a similar outcome in the treatment of distal fractures. However the locking plate is much more expensive than the non-locking plate.

La plaque verrouillée à vis poly-axiale apporte-t-elle un bénéfice dans l’ostéosynthèse distale de la fibula : étude cadavérique

BackgroundIn plate osteosynthesis involving the distal fibula, antiglide plating is superior to lateral plating in terms of the biomechanical properties. The goal of this study was to examine whether polyaxial-locking implants confer additional benefits in terms of biomechanical stability. MethodsSeven pairs of human cadaveric fibulae were subjected to osteotomy in a standardized manner to simulate an uncomplicated Weber B fracture. The generated fractures were managed with a dorsolateral antiglide plate. To this end, one fibula of the pair was subjected to non-locking plating and the other to polyaxial-locking plating. Biomechanical tests included quantification of the primary bending and torsional stiffness. In addition, the number of cycles to failure in cyclic bending loading was determined and compared. Bone mineral density was measured in all specimens. ResultsBone mineral density was comparable in both groups. Primary stability was higher in the polyaxial-locking group under torsional loading, and higher in the non-locking group under bending loading. The differences, however, were not statistically significant. All specimens except for one fixed-angle construct failed the cyclic loading test. The number of cycles to failure did not differ significantly between polyaxial-locking and non-locking fixation. ConclusionIn a cadaveric Weber B fracture model, we observed no differences in biomechanical properties between polyaxial-locking and non-locking fixation using an antiglide plate. Based on the biomechanical considerations, no recommendation can be made regarding the choice of the implant. Further biomechanical and clinical studies are required. Clinical relevanceInformation on the behavior of polyaxial-locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.

Does a polyaxial-locking system confer benefits for osteosynthesis of the distal fibula: A cadaver study

BackgroundIn plate osteosynthesis involving the distal fibula, antiglide plating is superior to lateral plating in terms of the biomechanical properties. The goal of this study was to examine whether polyaxial-locking implants confer additional benefits in terms of biomechanical stability. MethodsSeven pairs of human cadaveric fibulae were subjected to osteotomy in a standardized manner to simulate an uncomplicated Weber B fracture. The generated fractures were managed with a dorsolateral antiglide plate. To this end, one fibula of the pair was subjected to non-locking plating and the other to polyaxial-locking plating. Biomechanical tests included quantification of the primary bending and torsional stiffness. In addition, the number of cycles to failure in cyclic bending loading were determined and compared. Bone mineral density was measured in all specimens. ResultsBone mineral density was comparable in both groups. Primary stability was higher in the polyaxial-locking group under torsional loading, and higher in the non-locking group under bending loading. The differences, however, were not statistically significant. All specimens except for one fixed-angle construct failed the cyclic loading test. The number of cycles to failure did not differ significantly between polyaxial-locking and non-locking fixation. ConclusionIn a cadaveric Weber B fracture model, we observed no differences in biomechanical properties between polyaxial-locking and non-locking fixation using an antiglide plate. Based on the biomechanical considerations, no recommendation can be made regarding the choice of the implant. Further biomechanical and clinical studies are required. Clinical relevanceInformation on the behavior of polyaxial-locking plates is relevant to surgeons performing internal fixation of distal fibula fractures.

Investigation of Kryptonite™ bone cement in hybrid screw configurations of locking plate humeral midshaft fixation: A study of surrogate bone model

PurposeLocking compression plates (LCP) allow trauma and orthopedic surgeons to have a variety of options for utilizing locking and non-locking screw features. In this study, the hybrid constructs of mixed unicortical and bicortical screws were investigated for humerus midshaft fractures. The locking and non-locking features were also incorporated into the hybrid LCP constructs. Kryptonite™ bone cement is biocompatible with low exothermic properties and strong metal adhesion. This novel bone cement was incorporated into the non-locking screw feature to compare its mechanical effect with that of a traditional locking screw feature. MethodsA total of 24 synthetic bones (Sawbones® Inc., USA) were equally divided into three groups (n=8). The control group obtained traditional LCP fixation (JSM Medimax Inc., India) with bicortical screws, while the hybrid locking constructs employed a mix of bicortical and unicortical screws. The two bicortical screws in hybrid constructs were placed at the end holes of the LCP constructs and the unicortical screws were placed into the remaining holes. The hybrid locking (HL) group contained locking unicortical screws, whereas the hybrid non-locking group (HNK) utilized non-locking screw features incorporating the Kryptonite™ bone cement in the plate/screw bone construct. Specimens were tested by dynamic and static analysis. The eight total constructs were equally divided into two subgroups (n=4) to conduct axial compression and torsion test individually. The low cyclic test was conducted for dynamic analysis, which included 10,000 cycles at 1Hz frequency with a cyclic loading of 0–500N of axial force for the axial compression test and 0–20° of angular displacement for the torsion test. The static analysis was run by a failure test with a nondestructive strain rate of 0.1mm/s for the axial compression test and 0.5°s−1 for the torsional test. The construct stiffness of axial compression and torsion were derived from the linear portion of the load-displacement curves. The yield strength of axial compression and torsion was determined by using offset methods. The results of stiffness and yield strength were compared by using both one-way ANOVA and Scheffe and Games-Howell post hoc tests to analyze statically significant differences among the three groups. ResultsSpecimens completed 10,000 cycles in the dynamic analysis of axial and torsional cyclic tests without major deformation. To compare with the control group in static analysis, the HL and HNK groups achieved positive effect in axial stiffness, 12.3% and 10.5% greater than the control group respectively. HL obtained axial yield strength about 12% less than the control group. The HNK group was equivalent with the control group in axial yield strength. The torsional stiffness and yield strength were found similar in three groups, which indicated torsional equivalence among them. The stiffness and yield strength from axial compression and torsion were found statically non-significant among three groups. ConclusionsHybrid LCP constructs were initially showed to maintain equivalent axial and torsional stability with the traditional method. Kryptonite™ hosted mechanical and biological advantages for internal plate/screws (PLT) fixation.

Comparative study of fixation of proximal tibial fractures by nonlocking buttress versus locking compression plate

Background: Management of tibial plate fracture represents a challenging problem in developing countries. Aims: To compare the results of treatment of tibial plateau fractures with conventional nonlocking buttress plates (BP group) and locking compression plates (LCPs). Materials and Methods: The study was conducted on 30 patients with intra-articular closed fractures of the proximal tibia who were alternately assigned to two different treatment protocol, conventional nonlocking BP group or locking plates (LP group). Results : Schatzker Type II fracture was found to be the commonest fracture type with 13 patients. Only lateral plating was done in 24 patients, and dual plating was done in 6 patients. In 8 patients, corticocancellous bone graft were used. On follow-up complications like superficial skin necrosis (two cases), infection (two cases), varus collapse (three cases) developed. Sixty percent in LCP group, 66.6% in buttress group fractures clinically united in the time period of 7-9 weeks and 73.3% in LCP group and 80% in buttress group radiological union occurred in a period of 12-15 weeks. The results were graded in accordance with Poul S. Rasmussen's grading system. During the follow-up, 73.3% in LCP group and 66.6% in buttress group had no pain after clinical union. 66.6% patients in LCP group and 73.3% in buttress group could perform normal walking. About 86.6%in each group had no lack of extension. Nine patients (60%) in LCP group and 10 patients (66.6%) had flexion of up to at least 140°. About 86.6% in LCP group and 80% in buttress group had a stable joint in extension. Conclusion: Considering its high cost, LP group should only be used, where it is more advantageous than conventional plate.

A Comparison of Locking Versus Non-Locking Plates in Distal Femur Fractures

Background: Comminuted distal femur fractures are associated with a high complication rate and their treatment is difficult. This type of fracture is more common in young people with major trauma and following motor vehicle accidents. In old patients with osteoporosis the fractures are often closed and occur following a minor trauma. The aim of our study was to compare the outcomes and complications of treatment of intra-articular distal femur fractures using locking and nonlocking condylar buttress plates. Methods: In this retrospective study, 79 patients undergoing surgery due to type C distal femur fractures (T or Y condylar fracture) from 2008-2010 were included. Patients with comorbidities such as diabetes or end stage diseases and patients with other lower extremity fractures on the same side were excluded. For each patient demographic data including age, sex, mechanism of injury, and type of injury was collected. All patients were followed for at least one year postoperatively for complications such as infection, non-union, and malunion. Results: In this study 58 patients (73%) were male and 21 (23%) female. The mean age of the locking group was 37.4 ± 17.3 years and the nonlocking group 40.6 ± 17.3 years. There were no significant differences between the two groups in age and sex. In the locking group 36 patients (80%) had closed fractures and 9 (20%) open fractures and in the nonlocking group 25 patients (73.4%) had closed fractures and 9 (26.6%) open fractures. In both groups 5 patients had infections (11.1% in the locking group and 14.7% in the nonlocking group) and two patients each had nonunion (4.4% and 5.9% respectively). In the locking group 4 patients (8.9%) and in the nonlocking group 6 patients (17.6%) had plate failure. Conclusions: In our study the effects of treatment with both locking and nonlocking condylar buttress plates regarding infection and nonunion were similar but malunion and plate failure were higher in the nonlocking group. Nonetheless, this difference was not statistically significant.

Stability of unicortical locked fixation versus bicortical non-locked fixation for forearm fractures.

Locking plate fixation is being widely applied for fixation of forearm fractures and has many potential advantages, such as fixed angle fixation and improved construct stability, especially in osteoporotic bone. Biomechanical data comparing locking devices to commonly used Low Contact Dynamic Compression (LCDCP) plates for the fixation of forearm fractures has been lacking. The purpose of this study was to compare the fixation stability of a 3.5-mm unicortical locked plate with bicortical non-locked LCDCP plates. Six matched pairs of fresh frozen cadaveric forearms were randomly assigned to unicortical locked and bicortical unlocked groups. Non-destructive four-point bending and torsional test was performed on the ulna and radius separately, using a servohydraulic testing system to obtain construct stiffness of the intact specimens and specimens after osteotomy and plating. The specimens were then loaded to failure to test the fixation strength. The locked unicortical fixation showed significantly higher bending stiffness than the unlocked bicortical fixation, but with significantly lower stiffness and strength in torsion. Fixation strength was comparable between the two groups under bending, but significantly greater in the bicortical non-locked group under torsion. Findings from this study suggest that postoperative rehabilitation protocols may need modification to limit torsional loading in the early stage when using locked unicortical fixation. The study also points out the potential advantage of a hybrid fixation that combines locked unicortical and unlocked bicortical screws.

Comparative evaluation of 2.0-mm locking plate system vs. 2.0-mm nonlocking plate system for mandibular fractures — a retrospective study

The purpose of this retrospective study is to evaluate the efficacy of the 2.0-mm locking miniplate/screw system in comparison to the 2.0-mm nonlocking miniplate/screw system in mirror image mandibular fractures. A retrospective clinical trial was reviewed in the Department of Oral and Maxillofacial Surgery, Government Dental College, Pt. B.D. Sharma University of Health Sciences Rohtak for a period of 30 months (June 2007 to December 2009). A total of 30 patient pairs with isolated identical mandibular fracture (single or multiple) having 88 fractures were analyzed. A total of 11 complications that occurred represented 12.5% of the total. Six complications occurred at angle, three in the body and two at parasymphysis. Four complications occurred in the locking group and seven in the nonlocking group, with complication rates accounting for 9% and 16%, respectively. When comparing the overall complication rates according to plates used, the chi-square test showed no statistically significant difference between the locking and nonlocking plates (p > 0.05). Mandible fractures treated with the 2.0-mm locking plates and the 2.0-mm nonlocking plates present similar short-term complication rates.

Locking Versus Nonlocking Palmar Plate Fixation of Distal Radius Fractures

This study compared functional and radiological outcomes after treatment of extension-type distal radius fractures with conventional titanium nonlocking T-plates or titanium 1.5-mm locking plates. A total of 60 patients were included and followed for 4 to 7 years after receiving nonlocking T-plates (group A; n=30) or locking plates (group B; n=30) with and without dorsal bone grafting. Bone grafting was significantly more often performed in the nonlocking group to increase dorsal fracture fixation and stability (P<.003). Pre- and postoperative and follow-up values for palmar tilt, radial inclination, radial shortening, and ulnar variance were recorded. Age, sex, and fracture type were similarly distributed between the 2 groups. Postoperative and follow-up evaluation revealed equal allocation of intra-articular step formation and osteoarthritic changes to both groups. The overall complication rate was 25%. Compared with the nonlocking system, patients undergoing locking plate fixation presented with statistically significantly better values for postoperative palmar tilt (5.53° vs 8.15°; P<.02) and radial inclination (22.13° vs 25.03°; P<.02). However, forearm pronation was significantly better in group A (P<.005). At follow-up, radial inclination tended to approach a statistically significant difference in favor of group B. All clinical assessment, including Mayo wrist score, Disabilities of the Arm, Shoulder, and Hand score, Green and O'Brien score, Gartland and Werley score, visual analog scale score, and grip strength, yielded no statistically significant difference between the 2 groups. Locking plates seem to provide benefits regarding surgical technique and comfort, improvement in implant anchorage (especially in osteoporotic bone), and reduce the necessity of additional bone grafting.

Locking v/s non-locking reconstruction plates in mandibular reconstruction

Purpose:To compare the efficacy of locking plates to non-locking plates in the osteosynthesis of mandibular fractures on the basis of clinical parameters.Materials and Methods:A prospective randomized clinical trial was conducted at the Faculty of Dental Science, CSMMU (formerly King Georges Medical College), Lucknow, to treat consecutive mandible fractures. The patients were randomly divided into two groups. The patients underwent osteosynthesis—group 1 with 2.4-mm locking titanium plates and group 2 with 2.7 mm non-locking titanium plates. The cause of trauma, the number of days from injury to surgery, average age, gender, and site distribution were all reviewed. The assessment of the patients was done at 1, 3, and 6 weeks and 3 months using the clinical parameters.Results:A total of 12 patients with mandibular fractures met the inclusion criteria. In our study, a statistically significant difference was not found in the clinical parameters such as infection, paraesthesia, hardware failure, and mobility between the fracture segments. A statistically significant difference was found between pain and swelling from the previous follow-up visit in groups 1 and 2. In locking group, pain decreases significantly at 3rd week, 6th week, 12th week from 1st week and pain was absent after 3 week. In non-locking group, pain decreases significantly at 3rd week, 6th week and 12th week from 1st week but pain was present till 12th week. Pre-operative swelling was present only in case of non-locking group. Swelling was present in 66.7% of non-locking group and 0% in locking group. After one week swelling was absent in 100% patients at 3rd, 6th and 12th week. Swelling was considerably decreased in locking group as compared to the non-locking group.Conclusion:These findings show that the use of locking plates in mandibular fracture was efficacious enough to bear the masticatory loads during osteosynthesis of the fracture. The locking plates provide the advantage of a greater stability, with clinical results almost similar to those seen with non-locking plate osteosynthesis.

A Comparison of Locked Versus Nonlocked Enders Rods for Length Unstable Pediatric Femoral Shaft Fractures

Stainless steel flexible Enders rods have been used for intramedullary fixation of pediatric femur fractures with good success. Despite intraoperative anatomic alignment, length unstable femur fractures can present postoperatively with fracture shortening. The purpose of this study was to review all length unstable pediatric femoral shaft fractures in which Enders rods were used and compare those that were locked to those that were not locked. A retrospective clinical and radiographic review of all patients at a single institution undergoing flexible intramedullary fixation for length unstable femoral shaft fractures from 2001 to 2008. A length unstable fracture was defined as either a comminuted fracture or a spiral fracture longer than twice the diameter of the femoral shaft. A total of 107 length unstable femoral shaft fractures fixed with Enders rods were identified, of which 37 cases (35%) had both Enders rods "locked" through the eyelet in the distal femur with a 2.7 mm fully threaded cortical screw. Patient demographics, clinical course, complications, fracture characteristics, and radiographic outcomes were compared for the locked and nonlocked groups. There were no statistical differences between the groups in demographic data, operative variables, fracture pattern, fracture location, time to union, femoral alignment, or major complications. Shortening of the femur and nail migration measured at 1 to 6 weeks postoperatively was significantly greater for the nonlocked cases. The medial and lateral locked Enders rods moved 1.3 and 1.9 mm, respectively, and the unlocked Enders each moved 12.1 mm (P < 0.05). At final follow-up there were significantly more (P < 0.05) clinical complaints in nonlocked group, including limp, clinical shortening, and painful palpable rods. Locking Enders rods for length unstable pediatric fractures is an excellent option to prevent shortening and resulted in no additional complications, added surgical time, or increased blood loss. Level III.

Comparative evaluation of 2.0-mm locking plate system vs 2.0-mm nonlocking plate system for mandibular fracture: a prospective randomized study

This study evaluated the efficacy of a 2.0-mm locking plate/screw system compared with a 2.0-mm non-locking plate/screw system in mandibular fractures. A prospective randomized clinical trial was conducted. Patients were randomly assigned to receive 2.0-mm locking plates (group A) or 2.0-mm nonlocking plates (group B). All patients were followed up for 12 weeks postoperatively. Complications were analysed according to the type of plate used and the site of fracture. Fifty patients with 76 fractures met the inclusion criteria. Thirty-six fracture sites were treated with 2.0-mm locking plates and 40 with 2.0-mm nonlocking plates. The number of patients requiring postoperative maxillomandibular fixation was significantly higher in group B (p < 0.01); seven complications occurred representing 9% of the total. Two complications occurred in the locking group and five in the nonlocking group with complication rates equalling 6% and 13%, respectively. When comparing the overall complication rates according to plates used, the χ(2) test showed no statistically significant difference between the locking and nonlocking plates (p > 0.05). In conclusion, mandible fractures treated with 2.0-mm locking plates and 2.0-mm nonlocking plates present similar short-term complication rates.

Treatment of displaced clavicular shaft fracture: a comparison between locking and nonlocking reconstruction plating

Objective To retrospectively compare the therapeutic effects of straight locking and nonlocking reconstruction plating for displaced clavicular shaft fractures. Methods Between March 2006 and January 2010, 97 patients with single-sided, isolated, displaced clavicular shaft fractures (Edinburgh 2B)were treated with open reduction and plate fixation. Thirty-seven cases (22 males and 15 females with a mean age of 41.2 years) received straight locking reconstruction plating and 60 cases (37 males and 23 females with a mean age of 38.5 years) had nonlocking reconstruction plating. We compared the hardware failure rates and the Constant-Murley scores for the suffered shoulders between the 2 groups. Results The mean follow-up period was 10. 7 months (range, 6 to 12 months) in the locking group, and 9. 8 months (range, 6 to 12 months) in the nonlocking group. In the locking plate group, 33 fractures healed uneventfully with an average healing time of 4. 6 months (range, 3 to 6 months). In the nonlocking plate group, 58 fractures healed with an average healing time of 4. 1 months (range, 3 to 6 months) . A significantly higher plate breakage rate (10. 8% ) was observed in the locking plate group than in the nonlocking group (1.7%) (x2 = 3. 914, P =0. 048). The Constant-Murley score was 87.3 ±6. 5 (range, 82 to 95) in the locking plate group and 90.4 ±3.0 (range, 83 to 97) in the nonlocking plate group, without any significant difference between the 2 groups ( t = - 0. 730, P = 0. 467 ). Conclusion It may not be appropriate to treat a displaced clavicular shaft fracture, particularly a simple one, with a straight locking reconstruction plate. Key words: Clavicle; Fractures; Internal fixators; Case-control studies

The effect of the combination of locking screws and non-locking screws on the torsional properties of a locking-plate construct

Little is known about the torsional properties of bone-plate constructs when a combination of locking and non-locking screws have been used. Sixty cadaveric canine femurs were divided into three groups. In the first group, the plate was affixed using three non-locking screws. In the second group, only locking screws were used while a combination of one locking and two non-locking screws were used in the third group. All constructs were subjected to torsion until failure. Torque, angle of torsion, and work were all calculated at the maximum failure point, as well as at five degrees of plastic deformation, which was thought to be more representative of clinical failure. At the maximum failure point, the locking group had significantly higher torque, angle, and work values than the non-locking group. The combination group was intermediate to the two other groups, and significantly differed from the non-locking group in torque, and from the locking group in work. At five degrees of plastic deformation, the locking group required significantly higher torque and work than the non-locking group. The combination group required a significantly higher torque than the non-locking group. This study suggests that a construct composed of all locking screws will fail at a greater torque value, and sustain greater work to failure in torsion compared to a construct composed of all non-locking screws. The addition of a single locking screw to an otherwise non-locking construct will increase the torque at the offset failure point and may be of clinical value in constructs subjected to high torsional loads.

Comparative study of distal radial fractures in the elderly treated with locking and non-locking plates

To evaluate the clinical difference of locking and non-locking plates in the treatment of distal radial fractures in the elderly. Forty-nine patients with an average age of 68 years were included. The mean follow-up was 30 months. Five cases were traffic related injury, and others were simple falls. Fractures were classified according to AO classification system: 9 cases of A3, 4 cases of B, 11 cases of C1, 18 cases of C2, 7 cases of C3. Patients were grouped as locking group (29 cases) and non-locking group (20 cases). Significant difference was not found between the two groups in active range of motion, Gartland and Werley score, radiological measurements and score. Locking and non-locking plates have the same clinical outcome in the treatment of distal radial fractures in the elderly.

Locked vs. unlocked plate osteosynthesis of the proximal humerus – A biomechanical study

Locked plates (internal fixators) have been found to be an optimal method for the fixation in proximal humeral fractures. In a biomechanical cadaver study the difference between locked and non-locked osteosyntheses was investigated. Paired humeri were harvested, bone density measured. Locked internal fixators were mounted on one specimen; identical plate-screw-systems without locking mechanism applied to the contralateral specimen for comparison. After that, a transverse subcapital osteotomy was performed. With 7 pairs of humeri static tests with increasing axial loads and with 5 pairs dynamic tests with 10 N preload and 80 N maximal axial load for up to 1 million cycles were performed. In the static experiments the elastic stiffness of the construct was 74% higher in the locked group (median 80 N/mm, quartile range 77-86 N/mm) compared with the non-locked group (46 N/mm, 35.5-56.5 N/mm). The difference was statistically significant (Wilcoxon test for paired samples, P<0.05). Similarly, the linear range until failure was definitely extended in the locked group by 64% (92 N, 89-98 N vs. 56 N, 36.5-73.5 N, P<0.05). Under dynamic loading the non-locked group showed fixation failures between 97,000 and 500,000 cycles. In the locked group no failure was observed until the end of the experiment at 1 million cycles (P<0.0.5). The final deformation was found to be 1 mm (median, quartil range 1.0-1.2 mm) in the non-locked group and 0.3 mm (0.2-0.3 mm) in the locked group (P<0.05). The differences were found equally in lower as well as in higher bone density specimen. Because of the optimal load transfer between implant and cancellous bone, a locked screw plate interface will reduce fixation failure in proximal humeral fractures.