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.     

Osteonecrosis of the femoral head after osteosynthesis of a proximal femur fracture with a 95° condylar plate

Avascular necrosis of the femoral head is a frequent complication after osteosynthesis of femoral neck fractures. It is rarely seen after proximal femur fractures with intact trochanteric area. The choice of the implant varies from different blade systems (DHS, DCS and condylar plates) to intramedular nailing systems (gamma nail, classic nail). The complication of avascular necrosis of the femoral head after internal fixation of subtrochanteric and proximal femur fractures is reported following intramedullary nailing. We report a case of a femoral head necrosis after osteosynthesis of a proximal femur fracture with a 95 degree condylar plate.     

Osteonecrosis of the femoral head after osteosynthesis of a proximal femur fracture with a 95° condylar plate

Summary Avascular necrosis of the femoral head is a frequent complication after osteosynthesis of femoral neck fractures. It is rarely seen after proximal femur fractures with intact trochanteric area. The choice of the implant varies from different blade systems (DHS, DCS and condylar plates) to intramedular nailing systems (gamma nail, classic nail). The complication of avascular necrosis of the femoral head after internal fixation of subtrochanteric and proximal femur fractures is reported following intramedullary nailing. We report a case of a femoral head necrosis after osteosynthesis of a proximal femur fracture with a 95 degree condylar plate.      

Biomechanical evaluation of internal fixation for the treatment of comminuted subtrochanteric femur fractures

BackgroundSeveral biomechanical studies on subtrochanteric femur fractures have reported that use of an intramedullary nail is superior to extramedullary implant. However, the optimal choice of intramedullary nail for the treatment of comminuted subtrochanteric femur fracture remains unclear. Here, we evaluated the biomechanical properties of comminuted subtrochanteric femur fracture treated with four different internal fixations.MethodsA comminuted subtrochanteric femur fracture model was created with a 2-cm gap below the lessor trochanter in 20 synthetic femurs. The fractures were fixed with one of four implants - Antegrade Femoral Nail (AFN), Trochanteric Fixation Nail Advanced with a femoral neck blade (TFNA blade), TFNA with a femoral neck screw (TFNA screw), and the reversed distal femoral locking compression plate (DF-LCP) - all manufactured by DePuy Synthes. Axial compression tests and torsion tests were performed and the stiffness of each implant was compared.ResultsFor compression, the TFNA blade, TFNA screw, and AFN provided significantly higher stiffness than DF-LCP (p < 0.001, p < 0.001, p = 0.001, respectively), and the TFNA blade provided significantly higher stiffness than AFN (p = 0.049). For torsion, there were no significant differences among the groups in internal rotation, while the TFNA screw had significantly lower torsional stiffness than the AFN, TFNA blade and DF-LCP in external rotation (p = 0.036, p = 0.034, p = 0.037, respectively).ConclusionsThese findings could help to provide biomechanical evidence regarding choice of implant for the treatment of comminuted subtrochanteric femur fracture. The TFNA blade may be more suitable for the treatment of comminuted subtrochanteric femur fracture.     

Mechanical evaluation of a carbonated apatite cement in the fixation of unstable intertrochanteric fractures

We created three-part unstable intertrochanteric fractures in 6 pairs of aged, osteopenic, human, cadaveric femora. Fractures were reduced and fixed with a Dynamic Hip Screw (DHS) (Synthes, Paoli, PA). Two test groups were evaluated: 1. Fixation with DHS, and 2. Fixation with a DHS and calcium phosphate bone cement (Norian SRS (Skeletal Repair System)) augmentation of the fracture line and posteromedial calcar region of the proximal femur. Each femur was loaded to 1,650 N (2.5 body weight) for 10,000 cycles to simulate postoperative load transmission across the fracture construct during normal gait. The load was further increased successively by one body weight for another 10,000 cycles until failure. We evaluated fixation by measuring the amount of sliding of the lag screw of the DHS (shortening) and stiffness of the overall fracture construct (stability). SRS cement-augmented specimens had less shortening (1 mm versus 17 mm) and twice the initial construct stiffness compared to control specimens.     

Mechanical evaluation of a carbonated apatite cement in the fixation of unstable intertrochanteric fractures

We created three-part unstable intertrochanteric fractures in 6 pairs of aged, osteopenic, human, cadaveric femora. Fractures were reduced and fixed with a Dynamic Hip Screw (DHS) (Synthes, Paoli, PA). Two test groups were evaluated: 1. Fixation with a DHS, and 2. Fixation with a DHS and calcium phosphate bone cement (Norian SRS (Skeletal Repair System)) augmentation of the fracture line and posteromedial calcar region of the proximal femur. Each femur was loaded to 1,650 N (2.5 body weight) for 10,000 cycles to simulate postoperative load transmission across the fracture construct during normal gait. The load was further increased successively by one body weight for another 10,000 cycles until failure. We evaluated fixation by measuring the amount of sliding of the lag screw of the DHS (shortening) and stiffness of the overall fracture construct (stability). SRS cement-augmented specimens had less shortening (1 mm versus 17 mm) and twice the initial construct stiffness compared to control specimens.     

Locking plate constructs in subtrochanteric fixation: a biomechanical comparison of LCP screws and AO-nuts

ObjectivesVarious studies have reported the use of the 95-degree condylar blade plate in the treatment of a subtrochanteric fracture or non-union. However, the holding power of standard screws in the metaphyseal and diaphyseal area is often diminished due to osteopenia. The alternative in this area is the use of locking plates, Schühlis or AO-nuts. With the latter two, non-locking screws in the blade plate can be converted to a fixed angle fixation. The objective of this study was to compare the stiffness and strength of the AO-nut augmented 95-degree condylar blade plate construct with that of a locking plate construct. In addition, a clinical series of eight patients treated with the AO-nut augmented 95-degree condylar blade plate construct is presented.MethodsSingle screw-plate constructs of a 5.0 mm locking screw/locking compression plate (LCP) and a 4.5 mm non-locking screw/4.5 mm dynamic compression plate (DCP), converted to a fixed-angle screw construct using AO-nuts, were tested by cantilever bending. During loading, force and displacement were recorded, from which the bending stiffness (N/mm) and the yield strength (N) were determined. Secondarily, all patients that underwent surgical treatment for subtrochanteric fracture, malunion or non-union by the senior author using this technique, underwent chart review.ResultsThe stiffness of the locking screws was about four times higher compared to the AO-nut augmented construct. The yield strength was 2.3 times higher for the locking screw construct. In none of the eight patients treated with the fixed-angle blade plate, failure of the AO-nut augmented construct occurred.ConclusionsAlthough the stiffness and strength of the AO-nut augmented construct is less than of the locking screw, excellent clinical outcomes can be achieved utilizing this construct.     

Subtrochanteric fixation stability depends on discrete fracture surface points

Fixation of subtrochanteric femur fractures may present complications, including malunion, delayed union, or nonunion, and is thought to be related to early fracture stability. To examine the initial stability of subtrochanteric fracture fixation, we investigated construct stiffness, interfragmentary gaps, and overall and point-wise interfragmentary motion (ie, axial and shear displacements) in synthetic composite femurs fixed with a cephalomedullary nail or condylar blade plate. Simulated stable and unstable subtrochanteric femur fractures were created in composite femurs, anatomically reduced, fixed with either a long Gamma nail or a blade plate, and subjected to combined axial, bending, and torsional loading. The long Gamma nail group consistently showed greater displacement magnitudes than the blade plate group; these differences included axial and shear displacement magnitudes in the stable fracture group and shear displacement magnitudes in the unstable fracture group. Overall differences in fixation stability were dependent on discrete points around the periphery of the contiguous fracture surfaces, especially in the unstable fracture group. These differences in interfragmentary motion patterns between implant constructs were detected despite the lack of difference in combined axial, bending, and torsional construct stiffness or initial interfragmentary gap.     

AO动力髁螺钉在股骨粗隆下骨折中的应用

目的：研究和评估AO动力髁螺钉（dynamic condylar screw,DCS)在股骨粗隆下骨折治疗的价值和作用。方法：对36例股骨粗隆下骨折患者行切开复位、DCS内固定，结果：36例患者随访≥24个月，所有病例骨折均愈合，无一例发生钢板螺钉松动，断裂，骨不连等并发症，结论：DCS操作简单，可提供有效的固定稳定性，适用于股骨粗隆下骨折的治疗。     

Dynamic condylar screw: a new device. A preliminary report

The dynamic condylar screw (DCS) is a new implant engineered by the AO/ASIF Group for use in management of proximal and distal femoral fractures. This device has some technical advantages over the AO condylar blade plate. In a prospective study we reviewed the use of the DCS in the treatment of supracondylar fractures, intertrochanteric fractures, subtrochanteric fractures, nonunions, and malunions in 18 patients (19 femora). The results are based on an average follow-up of 9 months. Seventeen femurs went on to clinical and radiological union with good functional results. There were two failures because of delayed unions.     

Extramedullary fixation of 107 subtrochanteric fractures: a randomized multicenter trial of the Medoff sliding plate versus 3 other screw-plate systems

We compared the efficacy of a load-sharing device, the Medoff sliding plate (MSP), with that of 3 other load-bearing screw-plate devices for the fixation of subtrochanteric fractures in a randomized multicenter trial of 107 elderly patients. 55 fractures were operated on with the MSP, and 52 with the dynamic hip screw (DHS) with or without a trochanteric stabilizing plate (TSP) or with the dynamic condylar screw (DCS). The patient material in the groups was similar regarding age, domestic situation, preinjury walking ability and fracture types. We followed the patients clinically and radiographically for a minimum of 1 year. There was no significant difference in walking ability or return rate to the home at follow-up. Fixation failure occurred in 1/55 fractures operated on with the MSP, in 3/32 with the DHS, in 3/12 with the DCS and in 2/8 with the DHS/TSR The difference in the rate of fixation failure was statistically significant, when the MSP group was compared to the 3 load-bearing devices in the other group (1 vs 8). On the basis of this experience, we think that the load-sharing principle of the MSP, which seems to facilitate fracture impaction and stability, appears to be a good alternative in extramedullary fixation of subtrochanteric fractures.     

Treatment of unstable peritrochanteric femoral fractures using a 95 degrees angled blade plate

OBJECTIVE: To clarify the efficacy of a 95-degree angled blade plate fixation in the treatment of unstable peritrochanteric fractures of the femur. DESIGN: Retrospective, clinical study. SETTING: University hospital. PATIENTS: Thirty-nine consecutive patients with peritrochanteric femoral fractures were followed for a minimum of 12 months. There were 29 subtrochanteric fractures and 10 intertrochanteric fractures (reverse obliquity pattern) for which the compression hip screw could not be used because of comminution of the trochanteric area and fracture extension to the lateral cortex. The mean age of the patient population at the time of operation was 54 (range, 17-71) years. INTERVENTION: Open reduction and internal fixation of the pertrochanteric fractures using a 95 degrees angled blade plate. MAIN OUTCOME MEASUREMENTS: Time to fracture union, operation time, and complications. RESULTS: Duration of clinical follow-up averaged 26 (range, 12-36) months. The average time to osseous union for those fractures that healed primarily was 19 (range, 13-28) weeks. Two of 39 fractures united with 10 degrees varus deformity, but no corrective surgery was warranted. Limb length discrepancy more than 1.5 cm did not occur. Implant failure before solid bony union occurred in 1 case with a severely comminuted subtrochanteric fracture. Postoperative infection or osteonecrosis of the femoral head did not occur any time throughout the follow-up period. CONCLUSION: A 95 angled blade plate can be a useful alternative fixation device for the treatment of unstable peritrochanteric femoral fractures.     

Extramedullar fixation of 107 subtrochanteric fractures: A randomized multicenter trial of the Medoff sliding plate versus 3 other screw-plate systems

We compared the efficacy of a load-sharing device, the Medoff sliding plate (MSP), with that of 3 other load-bearing screw-plate devices for the fixation of subtrochanteric fractures in a randomized multicenter trial of 107 elderly patients. 55 fractures were operated on with the MSP, and 52 with the dynamic hip screw (DHS) with or without a trochanteric stabilizing plate fTSP) or with the dynamic condylar screw (DCS). The patient material in the groups was similar regarding age, domestic situation, preinjury walking ability and fracture types. We followed the patients clinically and radiographically for a minimum of 1 year.

There was no significant difference in walking ability or return rate to the home at follow-up. Fixation failure occurred in 1/55 fractures operated on with the MSP, in 3/32 with the DHS, in 3/12 with the DCS and in 2/8 with the DHS/TSP. The difference in the rate of fixation failure was statistically significant, when the MSP group was compared to the 3 load-bearing devices in the other group (1 vs 8).

On the basis of this experience, we think that the load-sharing principle of the MSP, which seems to facilitate fracture impaction and stability, appears to be a good alternative in extramedullary fixation of subtrochanteric fractures.     

Construct stiffness of different fixation methods for supracondylar femoral fractures above total knee prostheses

Supracondylar fracture of the femur after total knee arthroplasty has an estimated frequency of 0.6%-2.5% among total knee recipients and presents an extremely difficult problem when encountered. The goal of this study is to determine the most stable method of fixation of these supracondylar fractures among currently available devices. Synthetic composite femurs with properties similar to human bone were used, and identical, unstable supracondylar fractures were created in each. Osteotomized specimens were placed into four groups of five. Each group was then tested with one of four devices: the Green-Seligson-Henry (GSH) intramedullary nail, AO 95 degrees blade plate, dynamic condylar screw and sideplate, and condylar buttress plate. After stabilization with the different types of fixation, the constructs were tested individually for bending stiffness in four modes: flexion, extension, varus, and valgus bending. The stiffest fixation was determined in each of the four bending planes. Resistance to all tested directions was greatest for the condylar screw and sideplate construct. Resistance to flexion (stiffness = 30.96 N/mm), extension (stiffness = 36.36 N/mm), varus (stiffness = 35.46 N/mm), and valgus forces (stiffness = 32.26 N/mm) was highest in the group fixed with the dynamic condylar screw. This may be due to the purchase gained by the large lag screw into the distal femur, or it may be the result of the total rigidity of the implant. Although the femoral samples used in this study do not duplicate the typical osteopenic bone encountered at the site of a total knee arthroplasty, they do allow direct comparison of the fixation devices by removing the variability associated with cadaveric bone samples.     

Locking plates increase the strength of dynamic hip screws

INTRODUCTION: Failure of a dynamic hip screw (DHS) fixation leads to decreased mobility of the patient and frequently to a decrease in general health. The most common mode of failure of a DHS is cut out of the lag screw from the femoral head. The second most common mode of failure is lift-off of the plate from the femur. The aim of this laboratory-based experimental study was to determine whether a DHS secured to an osteoporotic femur with a locking screw plate would provide a stronger construct than the standard DHS plate. METHOD: The standard DHS design was compared to a DHS with fixed angle locking screws holding the DHS plate to the femur. Standard dynamic compression plates (DCP) and locking compression plates (LCP) were attached to synthetic, osteoporotic bone. A load was applied to replicate the forces occurring following the fixation of unstable, intertrochanteric hip fractures. A bracket on the proximal end of the plate replicated the lag screw in the femoral head. The constructs were cyclically loaded by a screw-driven material-testing machine and the number of cycles before failure occurred was determined. RESULTS: The mean number of cycles to failure for the locking plate construct was 2.6 times greater than for the standard screw construct (285 versus 108 cycles, respectively p=0.016). CONCLUSION: A dynamic hip screw with fixed angle locking screws would reduce the risk of DHS failure. A locking screw DHS would be particularly useful in patients with osteoporotic bone, and in patients with less stable fracture configurations.     

Split depression tibial plateau fractures: a biomechanical study

OBJECTIVE: To determine the biomechanical characteristics of four different fixation constructs for split depression fractures of the lateral tibial plateau (OTA classification 41B3.1). DESIGN: Laboratory investigation using a cadaveric simulated split depression tibial plateau fracture model. SETTING: Split depression tibial plateau fractures were created, reduced, and instrumented in a matched pair design. Specimens were tested for stiffness using a materials testing machine. INTERVENTION: Tibias were instrumented with an L-buttress plate, four 3.5-millimeter subchondral raft screws with an antiglide plate, an L-buttress plate with cancellous allograft, or four 3.5-millimeter subchondral raft screws placed through a periarticular plate. MAIN OUTCOME MEASUREMENTS: Vertical subsidence of the lateral tibial plateau was measured for the entire construct and for the local depression. The relative medial and lateral condylar tilt with central loading was also measured. RESULTS: There was no significant difference between the four fixation methods for overall longitudinal stiffness of the proximal tibial fracture fixation construct (range, 2,026 to 2,666 newtons per millimeter). The local depression stiffness for the raft-periarticular plate and raft-antiglide plate were 425 newtons per millimeter and 342 newtons per millimeter, respectively, versus 243 newtons per millimeter and 210 newtons per millimeter for the two large fragment buttress constructs. There was no significant difference between the local depression stiffness for the two raft constructs. There was no significant difference between the local depression stiffness for the two buttress plate constructs. Local depression stiffness was found to be significantly greater for the raft-periarticular plate construct when compared with the large fragment buttress plate construct without bone graft (p = 0.0314). Condylar tilt data showed a significant difference between the medial tilt observed in the prefracture specimen and the lateral tilt observed after fixation (p less-than-or-equal 0.017) for all constructs. CONCLUSIONS: There was no significant difference in the overall construct stiffness between the four fixation constructs. Fixation constructs with a raft of subchondral screws were more resistant to local depression loads. This supports the use of a raft construct when a central depression is a significant component of the overall fracture pattern. Condylar tilt data showed a persistent weakness in the postfixation lateral plateau regardless of fixation construct when compared with the intact specimen. This supports the current clinical practice of delayed weight-bearing for ten to twelve weeks.     

微创经皮钢板固定术结合动力髁螺钉治疗青壮年股骨转子下不稳定骨折

目的 评估微创经皮钢板固定术(minimally invasive percutaneous plate osteosynthesis, MIPPO)结合动力髁螺钉(dynamic condylar screw,DCS)治疗青壮年股骨转子下不稳定骨折的临床价值.方法 2001年1月至2006年1月,手术治疗25例股骨转子下不稳定骨折患者,男18例,女7例;年龄25～40岁,平均35岁;左侧12例,右侧13例;车祸伤20例,坠落伤5例.骨折按照Seinsheimer分型:ⅢA型15例,ⅢB型4例,Ⅳ型6例,均为闭合性骨折.手术均采用MIPPO结合DCS进行治疗.术后采用Harris评分对患髋关节功能进行评价.结果 所有病例均获得随访,随访时间9～24个月,平均16个月.骨折均全部骨性愈合,愈合时间3～4个月,平均3.5个月.无一例发生钢板断裂、螺钉松动退出及切割、骨折延迟愈合、再骨折、髋内翻畸形、肢体短缩等并发症.采用Harris评分法对患髋功能进行评价,优14例,良8例,可3例,优良率为92%.结论 运用MIPPO技术结合BO原理置入DCS可以有效减小手术创伤及减少手术并发症,有利于骨折愈合和髋关节功能恢复,是一种有效治疗股骨转子下不稳定骨折的方法.     

A new technique for insertion of barrel plate over dynamic hip/compression lag screw: a case report

Dynamic hip/compression screw (DHS/DCS) is one of the most commonly performed surgeries in orthopaedic practice.Sliding barrel plate over the DHS/DCS lag screw is one of the very crucial and at times u...     

Proximal femoral fractures. Is there an indication for the condylar screw (DCS)?]

Between 1983 and 1989 66 consecutive fractures of the proximal femur were treated with a condylar screw DCS. 42 patients were available for a follow-up study, 12 subtrochanteric fractures (mean age 58.5 years) and 30 intertrochanteric fractures (mean age 73 years). The primary union rate was clearly higher in the subtrochanteric group (10/12) compared to the intertrochanteric group (22/30). All the 8 implant complications (pull-out, metal fatigue) in the intertrochanteric group were associated with important posteromedial comminution in elderly patients who cannot be mobilized with only partial weight bearing postoperatively. Unstable intertrochanteric fractures in elderly patients should not be treated with the DCS. These are indications for the DHS which allows controlled telescoping. The indication for the DCS is limited to proximal shaft fractures in younger patients capable of partial weight bearing.