桡骨远端骨折掌侧与背侧接骨板固定的生物力学比较

目的 比较背侧移位桡骨远端骨折掌、背侧接骨板内固定后的生物力学性能,为桡骨远端骨折的治疗策略提供实验依据.方法 取6对12块人体桡骨远端标本,制作背侧移位桡骨远端骨折模型,配对标本一侧采用接骨板掌侧内固定,另一侧采用接骨板背侧内固定,固定完成后置于材料测试机上进行轴向压缩实验,实验模式为载荷破坏实验,记录载荷一位移曲线,获得标本破坏时的载荷和骨吸收的能量,实验结果进行统计学配对处理.结果 5对标本在轴向载荷下向掌侧发生成角倾斜,1对标本在轴向载荷下发生骨折端的嵌插.掌侧接骨板固定组的平均破坏载荷为[(1 520.05±579.56)N,x±s,下同],破坏时骨吸收的能量平均为(10.04 ±3.62)J;背侧接骨板固定组的平均破坏载荷为(1 326.77±384.86)N,标本破坏时骨吸收的能量平均为(8.21±3.74)J,组间对比差异无统计学意义(P>0.05).结论 掌侧接骨板固定是治疗桡骨远端骨折理想的固定方式.     

A biomechanical comparison of a dorsal 3.5-mm T-plate and a volar fixed-angle plate in a model of dorsally unstable distal radius fractures

OBJECTIVES: To compare the biomechanical stability of internal fixation of extra-articular, dorsally unstable distal radius fractures fixed by 1 of 2 methods, either a standard dorsal nonlocked T-plate or a volar locked fixed-angle plate. DESIGN: Biomechanical cadaveric study. SETTING: Biomechanical testing laboratory. INTERVENTION: In 6 matched pairs of fresh-frozen cadaveric specimens, a simulated unstable extra-articular distal radius fracture was created. The fractures were stabilized with either a dorsal 3.5-mm stainless steel T-plate or a titanium locked volar fixed-angle plate. Specimens were axially loaded at 5 points (centrally, volarly, dorsally, radially, and ulnarly) and then cyclically loaded for 5000 cycles with an 80 N central load. Postcyclical loading, specimens were once again axially loaded at the 5 points. MAIN OUTCOME MEASURES: Initial fixation stiffness and stiffness after midaxial cyclical loading was compared at the 5 points. RESULTS: With the volar locked fixed-angle plate, fixation was significantly stiffer than with the dorsal nonlocked T-plate for ulnar and volar loading in single-cycle testing. After cyclic loading, the locked volar fixed-angle plate maintained more of its initial stiffness than the dorsal nonlocked T-plate. The dorsal 3.5-mm stainless steel T-plate's stiffness when dorsally loaded significantly decreased after cyclical loading. CONCLUSIONS: The volar locked fixed-angle plate maintained a greater percentage of its initial stiffness after cyclic loading compared to the dorsal nonlocked plate. Also, the volar locked plate was stiffer than the dorsal nonlocked plate for all loading configurations tested except when subjected to a dorsally applied eccentric load.     

掌侧与背侧钢板固定关节外桡骨远端背侧粉碎性骨折的生物力学研究

目的 探讨掌侧与背侧钢板固定桡骨远端背侧粉碎性骨折时的抗压缩、抗扭转差异性.方法 将12侧新鲜成人尸体桡骨标本制成桡骨远端背侧粉碎性骨折模型,随机分为2个大组,分别进行掌侧与背侧钢板螺钉固定;再将每个大组分为2个亚组,分别进行轴向压缩试验和水平扭转试验.检测指标:轴向压缩强度、轴向压缩刚度、水平扭转强度和水平扭转刚度.结果 在轴向压缩试验中,掌、背侧两组之间轴向压缩强度差异有统计学意义(P＜0.05),背侧组大于掌侧组;在生理压缩载荷下,掌、背侧两组刚度值差异有统计学意义(P＜0.05),背侧组高于掌侧组.在水平扭转试验中,两组水平扭转强度与扭转刚度差异都没有统计学意义,但数据显示,掌侧组都略强于背侧组.结论 在抗压缩方面,两组的压缩强度以及压缩刚度差异均有统计学意义,背侧组要优于掌侧组;而在抗旋转方面,两组的扭转强度与扭转刚度差异均无统计学意义,但掌侧组在数据上均稍大于背侧组.     

Comparison of different distal radius dorsal and volar fracture fixation plates: a biomechanical study

PURPOSE: To compare the biomechanical properties of 6 dorsal and volar fracture fixation plate designs in a cadaver model. METHOD: Six different plating techniques were used on surgically simulated, unstable, extra-articular distal radius fractures in fresh-frozen cadavers. Specimens were tested to failure in axial compression with the Materials Testing System machine, and were analyzed with a motion analysis system. The 6 different fixation systems studied included an AO stainless steel Pi plate (group 1), an AO titanium Pi plate (group 2), a Forte plate (group 3), a dorsally placed Symmetry plate (group 4), a volarly placed Symmetry plate (group 5), and a volarly placed SCS/V plate (group 6). RESULTS: All dorsal plates (groups 1, 2, 3, 4) failed in apex dorsal angulation and all volar plates (groups 5, 6) failed in apex volar angulation. No group developed an average angular deformity greater than 5 degrees with a load of 100 N, which compares with the physiologic loads expected with active wrist motion. Only the volarly placed SCS/V plated specimens (group 6) resisted deformation of 5 degrees or more at loads up to 250 N, which compares with the physiologic loads expected with active finger motion, and was significantly stronger and more rigid than the other 5 plate groups. CONCLUSIONS: The SCS/V plate fixation system is the most rigid of the systems tested and may offer adequate stability for the treatment of the distal radius fracture in which the anterior and/or posterior metaphyseal cortex is comminuted severely.     

A biomechanical comparison between two volar locking plate systems for distal radius fractures

The biomechanical properties of two distal radius volar locking plate systems were investigated. A cadaveric model simulating distal radius fractures with dorsal comminution was selected. The biomechanical properties of fracture fixation using the Synthes volar locking T-plate and the Hand Innovation DVR plate were characterized. The average stiffness was 137.1 +/- 19.9 N/mm for the DVR group and 119.1 +/- 9.9 N/mm for the Synthes group (P = .49), and the average changes of the opening angle describing plastic deformation were 10.1 degrees +/- 4.0 degrees and 8.6 degrees +/- 13.2 degrees, respectively (P = .23). This study demonstrates that both the Synthes T-plate and Hand Innovations DVR plate fixation systems show comparable biomechanical characteristics.     

Surgical treatment of unstable distal radius fractures with volar locking plates

BACKGROUND: Surgical treatment of unstable distal radius fractures does not always yield a satisfactory outcome. The several surgical strategies available have problems associated with them. This study was undertaken to determine if volar locking plate fixation could be useful for treating unstable distal radius fractures. METHODS: This retrospective follow-up study assessed 24 fractures in 24 patients with unstable distal radius fractures surgically treated with one of three volar locking plate systems. According to the AO classification system, 7 patients had type A3 fractures, 5 patients had type C2 fractures, and the remaining 12 patients had type C3 fractures. Radiographic measurements included volar tilt, radial inclination, and ulnar variance. Clinical outcomes were evaluated by active range of motion of the wrist and forearm, grip strength, Saito's wrist score, and the Japanese Society for Surgery of the Hand version of the Disabilities of the Arm, Shoulder, and Hand questionnaire (JSSH version of the DASH). RESULTS: At the time of final follow-up (5 months minimum) the mean volar tilt was 8.1 degrees , radial inclination was 20 degrees, and ulnar variance was 0.4 mm. Mean wrist extension measured 61 degrees, wrist flexion 55 degrees, radial deviation 23 degrees, ulnar deviation 35 degrees, pronation 87 degrees, and supination 87 degrees. Grip strength recovered to a mean of 84% of the grip strength in the contralateral limb for patients who had injured their dominant hand and to a mean of 73% for patients who had injured their nondominant hand. Saito's wrist score calculations revealed 20 excellent and 4 good results. The mean DASH disability/symptom score was 9.9 points, and the mean DASH work module score was 8.2 points. CONCLUSIONS: The present study demonstrated that unstable distal radius fractures could be successfully treated with volar locking plate systems.     

Internal fixation of dorsally displaced fractures of the distal part of the radius. A biomechanical analysis of volar plate fracture stability

BACKGROUND: Volar plate fixation with use of either a locking plate or a neutralization plate has become increasingly popular among surgeons for the treatment of dorsally comminuted extra-articular distal radial fractures. The purpose of the present study was to compare the relative stability of five distal radial plates (four volar and one dorsal), all of which are commonly used for the treatment of dorsally comminuted extra-articular distal radial fractures, under loading conditions simulating the physiologic forces that are experienced during early active rehabilitation. METHODS: With use of a previously validated Sawbones fracture model, a dorsally comminuted extra-articular distal radial fracture was created. The fracture fixation stability of four volar plates (an AO T-plate, an AO 3.5-mm small-fragment plate, an AO 3.5-mm small-fragment locking plate, and the Hand Innovations DVR locking plate) were compared under axial compression loading and dorsal and volar bending simulating the in vivo stresses that are generated at the fracture site during early unopposed active motion of the wrist and digits. A single dorsal plate (an AO pi plate) was used for comparison, with and without simulated volar cortical comminution. The construct stiffness was measured to assess the resistance to fracture gap motion, and comparisons were made among the implants. RESULTS: The volar AO locking and DVR plates had greater resistance to fracture gap motion (greater stiffness) compared with the volar AO nonlocking and AO T-plates under axial and dorsal loading conditions (p < 0.01), with no significant difference between the AO volar locking and DVR plates. The volar AO locking plate had greater resistance to fracture gap motion than did the volar AO nonlocking plate under axial loading and dorsal bending forces (p < 0.01). The dorsal pi plate had the greatest resistance to fracture gap motion under axial loading and volar and dorsal bending forces (p < 0.01). However, the pi plate was significantly less stable to axial load and dorsal bending forces when the volar cortex was comminuted (p < 0.01). CONCLUSIONS: In this model of dorsally comminuted extra-articular distal radial fractures, dorsal pi-plate fixation demonstrated better resistance to fracture gap motion than did the four types of volar plate fixation. The AO volar locking and DVR plates conferred the greatest resistance to fracture gap motion among the four volar plates tested. Volar locking technology conferred a significant increase in resistance to fracture gap motion as compared with nonlocking plate technology.     

Outcome of dorsally comminuted versus intact distal radial fracture fixed with volar locking plates

Objective

Distal radial fractures are common. Modern trends favour operative treatment in many instances, providing stable fixation and early functional recovery. Recent biomechanical evidence suggests that volar locking plates (VLPs) enable adequate stability for dorsally displaced fractures, both in dorsally intact (DI) and in dorsally comminuted (DC) fractures. The aim of the study was to compare the clinical outcome of these two fracture groups treated with a VLP.

Methods

Retrospective case-control analysis of 91 distal radial fractures treated surgically using VLP by a single surgeon between the years 2006 and 2008 was carried out. Fractures were classified according to the Arbeitsgemeinschaft für Osteosynthes/Orthopaedic Trauma Association (AO/OTA) classification. Based on initial pre-reduction X-rays and computed tomography (CT) scans, fractures were classified into two groups of DI and DC fractures. The patients were re-evaluated at 2 and 6 weeks, 3 and 6 months and 1 year.

Results

Forty-one fractures (45%) were dorsally comminuted. Patients in the DC group were significantly older (mean 59 vs. 46 years, p < 0.01) and included more female patients, as well as significantly more C3 type fractures than the DI group (p < 0.04). The mean Disabilities of the Arm, Shoulder and Hand (DASH) score at 1 year postoperatively was 6.3 ± 2.3 for the DC group, as compared with 6.6 ± 2.02 for the DI group (p = 0.64). Average time to return to work was longer in the DC group (81.2 vs. 63.6 days, p = 0.05). Range of motion, volar tilt, and radial inclination were within clinically acceptable values and did not differ significantly among the two groups.

Conclusions

VLP fixation of DC distal radial fractures results in the maintenance of reduction and comparable functional and radiographical outcome with respect to DI fractures.     

Percutaneous pins versus volar plates for unstable distal radius fractures: a biomechanic study using a cadaver model

PURPOSE: A biomechanic study using a cadaver model of a dorsally unstable distal radius fracture was used to compare the stability of percutaneous pinning and volar fixed-angle plating. Among the many surgical options for treating distal radius fractures are percutaneous pinning and internal plate fixation. Although percutaneous pin fixation requires less soft-tissue trauma and has low complication rates, plate fixation allows for early active movement with good clinical results. The biomechanic stability of these 2 methods was studied by using a cadaver model of a dorsally unstable intra-articular distal radius fracture. METHODS: This study was performed on 7 fresh-frozen cadaver arms, in each of which an unstable intra-articular fracture with dorsal comminution was created. The fracture was first fixed with 0.062-mm K-wires inserted in standard crossed fashion and was tested in a pneumatic loading device that indirectly loaded the wrists through the 5 motor tendons 3 times at each level of force in flexion and extension. Testing was then repeated after removal of the pins and fixation with a fixed-angle DVR distal volar radius plate system (Hand Innovations, Inc., Miami, FL). Testing was performed in flexion up to 68 N and in extension up to 100 N, and the distance across the fracture site was measured. RESULTS: Volar plating was significantly more stable than pinning, with an average movement across the fracture site of 2.51 mm for pin fixation and 1.07 mm for plate fixation. The pins also showed a substantial degree of slipping after repeated stressing, but the plates remained stable. CONCLUSIONS: These results show the superior biomechanic stability of internal fixation using plates for dorsally comminuted intra-articular distal radius fractures in this cadaver model. Further clinical correlations are needed.     

Non-bridging external fixation employing multiplanar K-wires versus volar locked plating for dorsally displaced fractures of the distal radius

Background

The aim of this study was to compare non-bridging external fixation to palmar angular stable plating with respect to radiological outcome, wrist function, and quality of life.

Methods

One hundred and two consecutive patients (mean age: 63 years) were enrolled in the study. Fifty-two patients were randomized for plate osteosynthesis (2.4 mm, Synthes), 50 patients received non-bridging external fixation (AO small fixator). Objective (range of motion, grip strength), patient rated outcomes (quality of life, pain), and radiological outcome were assessed 8 weeks, 6 months, and 1 year after surgery.

Results

Loss of radial length of more than 3 mm was not detected in any group. Volar tilt was better restored by external fixation (7.2°) than by volar plating (0.1°). Wrist function was good in both groups. The external fixator was tolerated very well, and the quality of life assessment revealed comparable results in both groups. Osteoporosis was found in 54 % of patients and had no influence on radiological and functional outcome.

Conclusion

Non-bridging external fixation employing multiplanar K-wires is a suitable treatment option in intra- and extra-articular fractures of the distal radius even in osteoporotic bone.

Level of evidence

Prospective randomized trial, Level I.     

Locking versus nonlocking T-plates for dorsal and volar fixation of dorsally comminuted distal radius fractures: a biomechanical study

PURPOSE: To see if locking volar plates approach the strength of dorsal plates on a dorsally comminuted distal radius fracture model. Volar plates have been associated with fewer tendon complications than dorsal plates but are thought to have mechanical disadvantages in dorsally comminuted distal radius fractures. Locking plates may increase construct strength and stiffness. This study compares dorsal and volar locking and nonlocking plates in a dorsally comminuted distal radius fracture model. METHODS: Axial loading was used to test 14 pairs of embalmed radii after an osteotomy simulating dorsal comminution and plating in 1 of 4 configurations: a standard nonlocking 3.5-mm compression T-plate or a 3.5-mm locking compression T-plate applied either dorsally or volarly. Failure was defined as the point of initial load reduction caused by bone breakage or substantial plate bending. RESULTS: No significant differences in stiffness or failure strength were found between volar locked and nonlocked constructs. Although not significant, the stiffness of dorsal locked constructs was 51% greater than that of the nonlocked constructs. Locked or nonlocked dorsal constructs were more than 2 times stiffer than volar constructs. The failure strength of dorsal constructs was 53% higher than that of volar constructs. Failure for both volar locked and nonlocked constructs occurred by plate bending through the unfilled hole at the osteotomy site. Failure for both dorsal locked and nonlocked constructs occurred by bone breakage. CONCLUSIONS: Locking plates failed to increase the stiffness or strength of dorsally comminuted distal radius fractures compared with nonlocking plates. Failure strength and stiffness are greater for locked or nonlocked dorsal constructs than for either locked or nonlocked volar constructs. Whether the lower stiffness and failure strength are of clinical significance is unknown. The unfilled hole at the site of comminution or osteotomy is potentially a site of weakness in both volar locked and nonlocked plates.     

Functional outcome and complications after volar plating for dorsally displaced, unstable fractures of the distal radius

PURPOSE: Despite the recent popularity of volar plating for dorsally displaced distal radius fractures there is a paucity of data documenting the results of this treatment method. The purpose of this study was to determine the functional outcome of patients treated with volar fixed-angle plating for dorsally displaced, unstable distal radius fractures. METHODS: We reviewed the records of all patients treated at our institution with internal fixation using volar plates for dorsally displaced, comminuted distal radius fractures. Patients with follow-up periods shorter than 12 months were excluded from the study. Outcomes were evaluated at the latest follow-up examination with the Disabilities of the Arm, Shoulder, and Hand and the Gartland and Werley scoring systems. RESULTS: We studied 41 patients with a mean age of 53 years. The average follow-up period was 17 months. All fractures were stabilized with volar locking plates. Radiographs in the immediate postoperative period showed a mean radial height of 11 mm, mean radial inclination of 21 degrees , and mean volar tilt of 4 degrees. At fracture healing the mean radial height was 11 mm, mean radial inclination was 21 degrees, and mean volar tilt was 5 degrees. The average score on the Disabilities of the Arm, Shoulder, and Hand questionnaire was 14 and all patients achieved excellent and good results on the Gartland and Werley scoring system, indicating minimal impairment in activities of daily living. Nine patients experienced postoperative complications. There were 4 instances of loss of reduction with fracture collapse, 3 patients required hardware removal for tendon irritation, 1 patient developed a wound dehiscence, and 1 patient had metacarpophalangeal joint stiffness. CONCLUSIONS: Patients with unstable, dorsally displaced fractures of the distal radius treated with volar fixed-angle devices have good or excellent functional outcomes despite a high complication rate. When compared with previous reports on dorsal plating volar plates appear to have a higher incidence of fracture collapse but a lower rate of hardware-related complications. Complex fracture patterns thus mandate a careful and individualized approach. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level III.     

Biomechanical comparison of fixed-angle volar plate versus fixed-angle volar plate plus fragment-specific fixation in a cadaveric distal radius fracture model

PURPOSE: To test the hypothesis that combining orthogonal fragment-specific fixation with volar fixed-angle fixation provides markedly higher interfragment stability and construct strength compared with volar fixed-angle fixation alone. METHODS: Eight matched pairs of fresh cadaveric hand and forearm specimens were potted upright in cement. Flexor and extensor tendons were isolated at insertion sites and sutured into a looped bundle for loading in flexion and extension, respectively (up to 61 N). Osteotomies to simulate an AO type C2, 3-part fracture pattern were created with a saw. One randomized specimen from each pair received a locking volar plate and a radial pin plate (VP+PP), and the other received a locking volar plate only (VP). The relative angular displacements between the radial, ulnar, and proximal fragments were obtained with a motion analysis system. After stability tests, specimens were compressed to failure in a wrist-extended position on a material testing machine. Paired t tests were used to compare the interfragment displacement, construct stiffness, and strength between the 2 groups. RESULTS: Comparing fragment displacement in the VP+PP and VP groups showed that with flexion-extension and radial-ulnar deviation, distal fragment displacement was reduced to a statistically significant degree. The VP+PP group also showed higher failure strength and construct rigidity than the VP group. CONCLUSIONS: In a simulated cadaveric model of the distal radius intra-articular fracture, the combined technique of fragment-specific plating with volar fixed-angle fixation alone provides superior biomechanical strength and stability over the volar fixed-angle fixation alone.     

Dorsal screw penetration following implant removal after volar locked plating of distal radius fracture

Complications while removing implants are quite common. In rare cases screw shanks must be left in situ. We present a case of a 38-year-old patient who was treated using a palmar locking plate for a distal radius fracture. After implant removal, one of the screw shanks left in situ penetrated the dorsal cortex of the distal radius into the third extensor tendon compartment and led to irritation of the extensor pollicis longus tendon. We report the unexpected complication and analysis of possible errors of this case to avoid this kind of complication.     

Internal fixation of dorsally comminuted fractures of the distal part of the radius: a biomechanical analysis of volar plate and intramedullary nail fracture stability

Introduction  

The purpose of the present study was to carry out biomechanical testing of “new generation” volar plates and an intramedullary nail.     

固定角度掌侧接骨板结合克氏针治疗不稳定桡骨远端骨折

目的 探讨固定角度掌侧接骨板结合克氏针治疗不稳定桡骨远端骨折的临床效果.方法 2005年1月至2007年12月对19例不稳定桡骨远端骨折采用切开复位固定角度掌侧接骨板结合克氏针固定治疗,随访临床效果.结果所有患者随访5-14个月,平均11个月,所有患者均骨性愈合,愈合时间5-16周,平均愈合时间9.6周.掌倾角5°～12°,平均9.4°;尺偏角18°～24°,平均21°.6例轻度疼痛,4例活动受限,平均屈伸角度121°,平均握力为健侧的84.2%,桡骨长度得到恢复,关节面台阶＜1 mm.Cooney腕关节评分:优4例,良13例,可2例,优良率89.5%.结论 固定角度掌侧接骨板结合克氏针固定治疗不稳定桡骨远端骨折,可以获得满意的临床效果.