Biomechanical evaluation of a transcondylar screw from the dorsolateral plate support on the stabilization of orthogonal plate configuration in distal humeral fracture

Introduction

Intra-articular distal humeral fractures involving both columns require double-plate fixation. In orthogonal plate fixation, screws from the medial plate reach the radial column, while screws from the dorsolateral plate run posterior–anterior, not creating interdigitation. The Synthes LCP-DHP system has an orthogonal plate configuration that enables dorsolateral plating with support, as the radial and ulnar columns are linked via interdigitation of the distal screws. We hypothesized that the transcondylar screw from the posterolateral plate, which interdigitates with screws from the medial plate, enables more rigid stabilization of orthogonal plating in distal humeral AO type C fractures.

Supracondylar femur fracture fixation: mechanical comparison of the 95 degrees condylar side plate and screw versus 95 degrees angled blade plate

The best way to stabilize supracondylar femur fractures remains debatable. Previous studies have compared internal fixation to intramedullary fixation, but none have compared the stiffness characteristics and strength of the 95 degrees angled blade plate (ABP) with the 95 degrees condylar side plate and screw (DCS). 14 synthetic femora were cut in half and the proximal pole of the distal fragment was made secure. A 1 cm gap was made parallel to the femoral condylar weight-bearing surface to create an extraarticular supracondylar femur fracture (OTA 33-A3). 7 femora were stabilized with an ABP and 7 with a DCS. Using an MTS compression/torsion servohydraulic testing machine, each femur was tested in 7 modes of loading: (1) axial compression; (2) anterior compression; (3) posterior compression; (4) medial compression; (5) lateral compression; (6) torsion in external rotation; and (7) torsion in internal rotation. The stiffness of the construct in each mode, the "maximum load in axial compression", and the fatigue characteristics in axial compression were measured. The DCS showed a statistically significant greater stiffness in axial compression and average maximal load than the ABP. The fatigue tests revealed no evidence of permanent deformation or loosening of either construct.     

Supracondylar femur fracture fixation: Mechanical comparison of the 95° condylar side plate and screw versus 95° angled blade plate

The best way to stabilize supracondylar femur fractures remains debatable. Previous studies have compared internal fixation to intramedullary fixation, but none have compared the stiffness characteristics and strength of the 95° angled blade plate (ABP) with the 95° condylar side plate and screw (DCS). 14 synthetic femora were cut in half and the proximal pole of the distal fragment was made secure. A 1 cm gap was made parallel to the femoral condylar weightbearing surface to create an extraarticular supracondylar femur fracture (OTA 33-A3). 7 femora were stabilized with an ABP and 7 with a DCS. Using an MTS compression/torsion servohydraulic testing machine, each femur was tested in 7 modes of loading: (1) axial compression; (2) anterior compression; (3) posterior compression; (4) medial compression; (5) lateral compression; (6) torsion in external rotation; and (7) torsion in internal rotation. The stiffness of the construct in each mode, the "maximum load in axial compression", and the fatigue characteristics in axial compression were measured. The DCS showed a statistically significant greater stiffness in axial compression and average maximal load than the ABP. The fatigue tests revealed no evidence of permanent deformation or loosening of either construct.     

A biomechanical comparison of plate configuration in distal humerus fractures

OBJECTIVES: Our aim was to test the hypothesis that two plates placed parallel to each other are stronger and stiffer than plates placed perpendicular to each other for fixation of a distal humerus fracture model. METHODS: We created an artificial distal humeral fracture model by osteotomizing two groups of identical epoxy resin humera. Screw and plate constructs were built to mimic osteosynthesis. In the first group, 3.5-mm reconstruction plates were placed parallel to each other along each of the medial and lateral supracondylar ridges. In the second group, 3.5-mm reconstruction plates were placed perpendicular to each other with a medial supracondylar ridge plate and a posterolateral plate. Stiffness and strength data of the two constructs were obtained by testing to failure with sagittal plane bending forces. RESULTS: The parallel plate group (n = 7) had a mean stiffness of 214.9 +/- 43.3 N/mm and a mean strength of 304.4 +/- 63.5 N. The perpendicular plate group (n = 8) had a mean stiffness of 138.3 +/- 44.6 N/mm and a mean strength of 214.9 +/- 43.3 N. These differences were significant (Student's t test, P < 0.05). CONCLUSIONS: As theoretically expected, a parallel plate configuration is significantly stronger and stiffer than a perpendicular plate configuration when subjected to sagittal bending forces in a distal humerus fracture model.     

Bone resorption triggered by high radial stress: The mechanism of screw loosening in plate fixation of long bone fractures

Screw loosening is a common complication in plate fixation. However, the underlying mechanism is unclear. This study investigated screw loosening mechanisms by finite element analysis (FEA) simulation and clinical X‐ray feature analysis. Two FEA models incorporated bone heterogeneity and orthotropy, representing fracture fixation using dynamic compression plate (DCP) and locking compression plate (LCP), were developed. These models were used to examine the volume of bone exceeding a certain stress value around each screw under physiologically‐relevant loading conditions. These damaged bone was then separated and compared by the axial stress and radial stress of each screw. In addition, features of patients’ X‐ray images showing screw loosening were analyzed to validate the loosening features simulated by the models. The FEA study showed that more damaged bone was found at the central two screws which gradually decreased toward the two end screws in all groups. More bone was damaged by the radial stress of each screw than by the axial stress. The radiological analysis of screw loosening showed that bone loss occurred at the screw closest to the fracture line first then subsequent bone loss at the screws further away from the fracture line occurred. This study found that the two screws nearest to the fracture line are more vulnerable to loosening. The radial stress of the screw plays a larger role in screw loosening than the axial stress. Bone resorption triggered by the high radial stress of screws is indicated as the mechanism of screw loosening in the diaphyseal plate fixation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1498–1507, 2019.     

Hypoplasia of the humeral trochlea

Radiographic studies of three cases of hypoplasia of the humeral trochlea were done. Several other anomalies were also detected, including a hypoplastic capitellum in case 2, a hyperplastic radial head in cases 2 and 3, and bulging of the loose joint capsule in case 3. Operations in cases 1 and 3, disclosed that ganglions and fibrous septa compressed the ulnar nerve. The cause of ulnar nerve palsy in patients with hypoplasia of the humeral trochlea is thought to be associated with the high incidence of ganglions in hypoplastic elbow joints. The ganglion may play a role.     

Posterolateral rotatory instability of the elbow

Posterolateral rotatory instability of the elbow is a three-dimensional displacement pattern of abnormal external rotatory subluxation of the ulna coupled with valgus displacement on the humeral trochlea. This pattern causes the forearm bones to displace into external rotation and valgus during flexion of the elbow. Injury to the lateral ulnar collateral ligament allows abnormal supination of the ulna on the humerus. The radial head, being locked in the sigmoid (radial) notch of the proximal ulna by the annular ligament, subluxates posterior to the capitellum. The abnormality is usually posttraumatic and presents with locking, snapping, clicking, catching, and recurrent dislocation of the elbow. The clinical diagnosis is suspected from history and confirmed by the physical examination, which includes the posterolateral rotatory instability test. This test often is best performed under fluoroscopy or general anesthesia. Usually the instability is managed with either a repair of the ligament or an isometric reconstruction using a tendon graft.     

儿童肱骨髁上骨折移位程度与Baumann角关系的分析研究

目的:应用Excel软件对小儿肱骨髁上骨折的桡尺侧移位值和Baumann角进行数值拟合分析,得出相关数据曲线,以期用于指导临床小儿肱骨髁上骨折治疗。方法:收集2010年7月至2011年7月间就诊的小儿肱骨髁上骨折病例56例(年龄3～14岁;男34例,女22例;桡偏型15例,尺偏型41例)。采用数据测量工具MB-Ruler,测量各病例X线片骨折的移位值及Baumann角,将数值录入于Excel,分别对56组骨折的移位值和Baumann角,以及15组桡偏型、41组尺偏型数值行拟合分析,并对所得数据曲线进行分析。结果:用2种方式进行拟合所得出结果相近,即尺偏切线斜率>桡偏切线斜率;当桡偏系数<-0.18,尺偏系数>0.50时,Baumann角有反向改变的趋势,即Baumann角变化范围在65.70°～96.77°;当尺偏系数≥0.15时,Baumann角≥82°。结论:小儿肱骨髁上骨折尺偏移位对Baumann角的影响大于桡偏移位,当尺偏系数≥0.15时应注重纠正,预防肘内翻发生。     

Danger zone for locking screw placement in minimally invasive plate osteosynthesis (MIPO) of humeral shaft fractures: A cadaveric study

Several recent reports have described the minimally invasive plate osteosynthesis (MIPO) technique in the treatment of humeral shaft fractures by the anterior approach. The purpose of this study is to identify the danger zone for locking screw placement to avoid musculocutaneous nerve injury in the anterior compartment and radial nerve injury in the posterior compartment of the humerus relative to the humeral length. Eighteen arms of fresh cadavers were fixed with 10-hole locking compression plate (LCP) by anterior approach using the MIPO technique. Two locking screws on each end were fixed by the open technique; the rest of the screws were inserted percutaneously. The arms were dissected both anterior and posterior to identify musculocutaneous and radial nerve injuries. Humeral length with a simple palpable bony landmark was measured from the posterior tip of the acromion process to the lateral epicondyle. Damage or direct contact of the locking screws to the musculocutaneous or radial nerve was recorded, and the distance between the screws and the radial nerve was measured.The average humeral length was 29.71 cm (99% confidence interval (CI): 28.54-30.86 cm). The danger zone for the musculocutaneous nerve averaged 18.37% (99% CI: 17.06-19.60) to 42.67% (99% CI: 42.33-43.03) of the humeral length from the lateral epicondyle. The danger zone for the radial nerve averaged 36.35% (99% CI: 35.81-37.07) to 59.20% (99% CI: 59.00-59.46) of the humeral length, and the most dangerous screws that penetrated or touched the radial nerve lay 47.22% (99% CI: 45.27-49.17) to 53.21% (99% CI: 51.16-55.33) of the humeral length from the lateral epicondyle. An anteroposterior locking screw placed percutaneously endangered the musculocutaneous and radial nerves.From this cadaveric study, the danger zone for the musculocutaneous and radial nerves could be determined as a percentage of the humeral length. Since the zone with radial nerve injuries shows a large variation, this procedure should only be done by experienced surgeons.     

Minimally invasive plate osteosynthesis for metastatic pathologic humeral fractures

Because patients with metastatic bone disease may survive only 3 to 12 months, the goal of surgery for pathologic fractures is to attain rigid and durable internal fixation and immediate postoperative use of the upper extremity. Surgical options such as intramedullary nailing, plating, and insertion of prosthesis usually reinforced with bone cement have been proposed for pathological humeral fractures. We describe a 42-year-old man with a pathologic distal humeral fracture. The fracture location and lack of distal bone stock precluded the use of intramedullary nails. We performed minimally invasive plating by using a locking plate for bridging and stabilization of fracture. Minimally invasive plate osteosynthesis of the humeral shaft was developed to allow anterior plate and screw stabilization involving less soft tissue disruption and to theoretically improve healing rates and reduce complications, such as infection and iatrogenic radial nerve palsy. Plain radiographs showed stable consolidation of the fracture without screw loosening at the 7-month follow-up. Elbow range of motion was 120°, and the arm was stable without pain. Minimally invasive plate using a locking plate can provide stable fixation and allow early arm mobilization without protection and decrease the risk of operation-related complications, making it a useful surgical alternative in the treatment of pathologic humeral fractures.     

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis

BackgroundLocking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included “locking and dynamic holes separated” and “locking hole only” configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate.MethodsFinite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A “virtual” subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison.ResultsThe mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6 N/mm) compared with the combi design (115.0 N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5 N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design.ConclusionsThe computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture.     

Anteromedial minimally invasive plate osteosynthesis (MIPO) for distal third humeral shaft fractures – Is it possible?: A cadaveric study

IntroductionThe purpose of this study was to evaluate the feasibility of the anteromedial minimally invasive plate osteosynthesis (MIPO) approach for distal third humeral shaft fractures and identify neurovascular structures at risk with this approach.MethodsTwenty cadaveric arms were fixed with 12-hole precontoured narrow locking compression plates (LCP) with the anteromedial approach using MIPO technique. The proximal approach was done between the biceps and deltoid muscle directly to the bone. The distal approach involved elevating the brachialis from medial intermuscular septum. The plate was inserted beneath the brachialis tunnel from distal to proximal. Three locking screws were fixed at each end through incisions and the rest of screws were inserted percutaneously. The arms were then dissected to identify damage to or direct contact between the screws and brachial artery (BA), median nerve (MN), musculocutaneous nerve (MCN), and radial nerve (RN). The distances from the screws to structures at risk, humeral length, and length of three distal screws in mediolateral (ML) direction were measured.ResultsThe average humeral length was 28.97 cm. The average danger zone for the BA and MN were 20.47%–62.66% of the humeral length from the lateral epicondyle, and 20.47%-75.02% for the MCN. The ulnar nerve was not endangered by this approach as it lies posteromedially to the humerus. The danger zone for the RN averaged 27.07%–43.74%, and the most dangerous screw that either penetrated or touched the nerve was at the fifth hole, which lay at 33.14% of the humeral length. The average length of three distal screws in ML direction were 41.4, 25.0 and 22.5 mm.ConclusionsThe anteromedial MIPO approach can be performed through the internervous plane beneath the brachialis muscle without exposing any nerves or causing any muscle splitting with a 12-hole plate. Both proximal and distal screw insertion must be done with direct exposure. Insertion of percutaneous screws in the middle part of the plate between the two incisions is not possible. This approach could be an alternative for extra-articular distal third humeral shaft fractures which provides less invasive surgical dissection, allows the use of longer distal screws, and achieves better cosmesis.     

Functional outcome of supracondylar humerus fracture in children with the use of pin configuration as per Bahk classification

IntroductionA variety of fracture patterns are seen in supracondylar humerus fractures in children and these are well described by Bahk et al. Currently followed treatment protocol doesn’t recognize these common fracture patterns and pin placement is done at the discretion of the treating surgeon. The aim of the study is to evaluate the usefulness of Bahk classification system in deciding the pin configuration for the specific fracture patterns and thereby assess the functional outcome in the management of supracondylar fractures in children.MethodThe study was done on 100 children of 2–12 years of age from February 2019 to January 2020. After closed reduction under general anesthesia, fractures were classified and pin configuration was decided according to Bahk classification. In the follow-up, patients were assessed for clinicoradiological outcomes based on Modified Flynn’s criteria, Baumann angle, and anterior humeral line.ResultsIn our study Typical transverse and low sagittal fracture were the most common fracture patterns. In the final follow up as per Flynn’s criteria, 93% of the patients showed excellent results. Mean Baumann’s angle was not significantly different from the uninjured side and anterior humeral line passed through anterior or middle third of the capitulum in 95% patients.ConclusionUsing pin configuration suitable to fracture pattern as per Bahk classification improves functional outcome in supracondylar humerus fractures in children and minimizes complications.     

Biomechanical comparison of three internal fixation configurations for low transcondylar fractures of the distal humerus

BackgroundWe aimed to evaluate the biomechanical stiffness and strength of different internal fixation configurations and find suitable treatment strategies for low transcondylar fractures of the distal humerus.Methods and materialsThirty 4^th generation composite humeri were used to create low transcondylar fracture models that were fixed by orthogonal and parallel double plates as well as posterolateral plate and medial screw (PPMS) configurations (n=10 in each group) using an anatomical locking compression plate-screw system and fully threaded medial cortical screws. Posterior bending (maximum 50 N), axial loading (maximum 200 N) and internal rotation (maximum 10 N·m) were tested, in that order, for each specimen. Stiffness under different biomechanical settings among different configurations were compared. Another 18 sets of fracture models were created using these three configurations (n=6 in each group) and the load to failure under axial loading among different configurations was compared.ResultsUnder posterior bending, the stiffness of parallel group was higher than orthogonal group (P<0.001), and orthogonal group was higher than PPMS group (P<0.001). Under axial loading, the stiffness of parallel group was higher than orthogonal group (P=0.001) and PPMS group (P<0.001); however, the difference between orthogonal and PPMS group was not statistically significant (P>0.05). Under internal rotation, the stiffness of parallel group was higher than orthogonal group (P=0.044), and orthogonal group was higher than PPMS group (P=0.029). In failure test under axial loading, the load to failure in the orthogonal group was lower than parallel group (P=0.009) and PPMS group (P=0.021), but the difference between parallel group and PPMS group was not statistically significant (P>0.05). All specimens in orthogonal group demonstrated “distal medial failure”; most specimens had “distal medial and trochlear failure” in the parallel group; most specimens exhibited “contact failure” in the PPMS group.ConclusionFor treating low transcondylar fractures, the overall stiffness and strength of the parallel configuration were superior to those of the orthogonal and PPMS configurations. Nevertheless, the PPMS configuration can provide adequate stability and stiffness comparable to double-plate configurations under axial loading. Therefore, the PPMS construct may have certain clinical value.     

儿童肱骨髁上骨折伴神经血管损伤的治疗

目的：探讨针对伴有神经、血管损伤的儿童肱骨髁上骨折的治疗方法。方法：自2002年2月至2007年11月手术治疗闭合复位不满意的Ⅱ型和Ⅲ型肱骨髁上骨折儿童96例,男59例,女37例;年龄4～16岁,平均6.4岁。16例手术患儿出现17个神经损伤症状,桡神经损伤5例,正中神经损伤7例,其中1例伴有尺神经损伤,尺神经损伤4例;13例出现肢体远端桡动脉搏动减弱、手凉血管损伤症状。比较患肢术前、术后神经、血管恢复情况,必要时应用肌电图、多普勒超声明确诊断和指导进一步治疗。结果：96例患儿85例术后随访6～18个月,平均11个月,73例患儿切口Ⅰ愈合,12例切口Ⅱ期愈合,无感染及肘关节功能障碍。5例桡神经损伤病例中3例桡神经损伤患儿术后3个月桡神经损伤症状完全消失;1例术后3个月行桡神经探查松解术,术后5个月症状消失;1例医源性桡神经损伤解除石膏压迫3个月后神经功能完全恢复。正中神经损伤7例,其中1例伴发尺神经损伤,6例正中神经损伤患儿术后6个月神经功能完全恢复;伴有尺神经损伤的病例Ⅱ期行神经探查,术后9个月神经损伤症状消失。尺神经损伤5例,其中伴发正中神经损伤1例,尺神经损伤病例术后6个月神经症状完全消失。术前出现桡动脉搏动弱、手凉症状13例,术中未行血管探查,骨折固定后桡动脉损伤症状消失。结论：肱骨髁上骨折Ⅰ期手术过程中常规探查尺神经、正中神经和桡神经,及血管是否探查根据术前查体决定,肌电图及多普勒超声不作为术前常规检查项目。     

锁定加压钢板与解剖型钢板内固定治疗肱骨近端骨折疗效比较研究

目的：对比分析锁定加压钢板与解剖型钢板内固定治疗肱骨近端骨折的临床效果,探讨合适的肱骨近端骨折内固定方法。方法对2007年1月至2013年1月苏州市第七人民医院收治的63例肱骨近端骨折患者的临床资料进行回顾性分析,其中31例采用锁定加压钢板固定,32例行解剖型钢板固定。观察术后并发症发生情况,根据Neer评分标准对疗效进行评定。结果锁定加压钢板组25例患者获得有效随访,随访时间6～36个月,平均随访时间16个月;解剖型钢板组29例患者获得有效随访,随访时间7～48个月,平均随访时间26个月。锁定加压钢板组术后肩关节功能Neer评分优良率优于解剖型钢板组,但两组比较,差异无统计学意义（96% vs 90%,P＞0.05）。解剖型钢板组1例患者发生肱骨头坏死、吸收,2例出现螺钉松动、部分拔出。两组均未出现断钉、再骨折移位、骨折不愈合、桡神经损伤、腋神经损伤等术后并发症。结论锁定加压钢板和解剖型钢板内固定均能有效治疗肱骨近端骨折,但锁定加压钢板内固定并发症少,更加安全可靠。     

髋臼前柱钢板内固定的解剖学研究

目的研究髋臼前柱钢板内固定技术中螺钉的最佳进钉点、方向和长度,预防发生螺钉穿入关节内的严重并发症。方法取成年男性半骨盆标本20个,分别测量髋臼前、后缘到髂前下棘、髂耻隆起和耻骨结节的距离,确定和制作髋臼前柱系列断面,分别测量各断面上各进钉点的安全进钉角度,将测量数据输入到SPSS10.0软件进行统计学分析。结果髋臼前缘到髂前下棘、髂耻隆起和耻骨结节的距离分别为(25.4±1.4)mm,(11.8±0.7)mm和(37.4±1.5)mm,后缘到髂前下棘和髂耻隆起的距离分别为(15.5±0.9)mm和(29.1±1.6)mm。在各断面距离骨盆界线0.5cm点、1.0cm点和1.5cm点上螺钉的安全进钉角度的最大值分别为(8.2±2.2)°、(14.9±3.4)°和(26.1±4.5)°。结论在前柱髋臼区使用钢板内固定时,可以采用3种方法避免螺钉穿入关节内。第一种方法是使用短螺钉,螺钉方向随意;第二种方法是使用长螺钉紧贴骨盆界线进钉,方向平行于四方区;第三种方法为根据不同的进钉点选择不同的进钉角度和长度。     

Clinical significance of anterior humeral line in supracondylar humeral fractures in children

IntroductionAnterior humeral line (AHL) location is commonly used to evaluate sagittal alignment after fracture reduction in children with supracondylar humeral fractures. However, the position of the AHL for acceptable fracture reduction has not been validated by clinical outcome. The purpose of this study was to investigate the relationship between the location of AHL and range of elbow motion.Patients and methodsWe retrospectively reviewed 101 children who underwent closed reduction and percutaneous pinning for Gartland type III supracondylar humeral fractures between January 2009 and June 2014. There were 67 boys and 34 girls, with a mean age of 7 years. The children were classified according to the location of the AHL three months postoperatively into five groups: anteriorly loss (n = 6), anterior third (n = 25), middle third (n = 47), posterior third (n = 21), and posteriorly loss (n = 2). Range of elbow motion was measured by attending paediatric orthopaedic surgeons with a goniometer. Clinical and radiographic outcomes were compared among the five groups.ResultsThe mean elbow extension angle was not significantly different among the groups (p = 0.21). However, children with AHL anterior to the capitellum had less elbow flexion angle (125.8° vs. 131.2°, p = 0.046) and less total range of elbow motion (128.3° vs. 135.7°, p = 0.048) than children with AHL crossing the capitellum. When the AHL crossed the capitellum, the elbow flexion angle and total range of elbow motion were significantly decreased in children with AHL crossing the anterior third of the capitellum. The Flynn criteria were not significantly different among the central three groups (p = 0.131). However, the Flynn criteria were significantly worse in children whose AHL missed the capitellum (p < 0.001). The mean Baumann angle measured 3 months postoperatively was not significantly different among the groups (p = 0.12).ConclusionsThese findings demonstrate that children with AHL crossing the middle and posterior thirds of the capitellum appear to have slightly better early elbow flexion and total range of elbow motion. AHL crossing the anterior third of the capitellum can be an underreduction that has similar elbow motion as AHL anterior to the capitellum. AHL posterior to the capitellum is a warning sign of overreduction and should be avoided.     

Lateral versus crossed wire fixation for displaced extension supracondylar humeral fractures in children

Reduction and percutaneous pin fixation is widely accepted treatment for displaced humeral supracondylar fractures in children, but the best pin configuration is still debatable. This study examined the outcome for crossed and lateral pins placement in type IIB and III supracondylar humeral fractures. Clinical notes and radiographs of 131 children with an average age of 6 years were retrospectively reviewed. Lateral pins fixation was used in 66 children and crossed wires in 65. The groups were similar with regard to gender, age, follow-up, severity of displacement and number of closed/open reductions. There was no statistical difference between the two groups either clinically or radiologically in the quality of outcome. However, postoperative ulnar nerve injuries occurred in 6% of patients treated with crossed wire fixation, whilst none of the group with pins inserted laterally suffered this complication. We recommend fixation of displaced humeral supracondylar fractures with two or three lateral pins inserted parallel or in a divergent fashion. This method of fixation gives similar results to crossed wires but prevents iatrogenic ulnar nerve injuries.     

Ultrasound imaging of the humeral capitellum: a cadaveric study

Background Ultrasound is suitable for routine examinations of capitellar osteochondritis dissecans because it can visualize both the subchondral bone and the overlying articular cartilage non-invasively. The radial head interferes with the sonographically visible area of the articular surface of the humeral capitellum, although the precise extent of this is currently unknown. This study aimed to investigate the visible area of the humeral capitellum using both anterior and posterior ultrasonographic scans.Methods Twelve elbows were used from cadavers with a mean age of 85.6 years. After marking a 45° angle in the anterior capitellum in a caudal direction using a drill, anterior and posterior, long-axis ultrasonographic scans were performed with the cadaveric elbows bent. The elbow-flexion angle at which the 45° point was obscured by the radial head was measured and these ultrasonic measurements were then verified by macroscopic observation.Results The elbow-flexion angle at which the 45° point was obscured by the radial head was 24° in anterior scans and 102° in posterior scans. These ultrasonic measurements corresponded to the macroscopic measurements. The results showed that anterior, long-axis ultrasound scans could visualize the capitellum from 45° through the rest of the anterior area at 24° flexion of the elbow: the radial head obscured the area of the capitellum that is 21° anterior to the elbow flexion angle. Similarly, posterior long-axis scans could visualize the capitellum from 45° through the rest of the posterior area at 102° flexion of the elbow: the radial head obscured the area of the capitellum that is 57° posterior to the elbow flexion angle. The radial head obscured a 78° (21° + 57°) arc of the capitellum in ultrasonography.Conclusions This study thus clarified the area of the humeral capitellum visible in both anterior and posterior ultrasound scans in the sagittal plane.