Capitellum fractures: a biomechanical evaluation of three fixation methods

OBJECTIVE: To determine the relative stability of three fixation methods for displaced capitellum fractures. DESIGN: Twelve matched pairs of embalmed humeri were divided into two equal groups and simulated capitellum fractures created. The first group compared cancellous lag screws placed in an anteroposterior direction to screws placed in the posteroanterior direction. The second group compared the Acutrac compression screw, inserted anteroposteriorly, to the more stable construct from the first test group. METHODS: All specimens were cyclically tested with simulated physiologic loading. Both displacement of the capitellum over a range of cycles and the number of cycles to failure were recorded. RESULTS: Fixation with posteroanteriorly directed cancellous lag screws was significantly more stable than anteroposteriorly directed screws at 2000 cycles (p = 0.007); loads to failure were not statistically different. Fixation by the Acutrac screws was significantly more stable than posteroanterior cancellous screws at 2000 cycles (p = 0.03). The Acutrac fixation had a higher failure load; however, this was not statistically significant. CONCLUSION: The headless screws tested in this biomechanical study provided more stable fixation of capitellum fractures in the cadaveric specimens than four-millimeter partially threaded cancellous lag screws and may do so in the clinical setting. When the cancellous lag screws were tested, insertion in the posteroanterior direction provided more stable fixation than the anteroposterior direction and has clinical benefit of not violating the articular surface. Ultimately, the decision of which method to use lies with the attending surgeon and the technique with which he or she feels most comfortable.     

Internal fixation of femoral neck fractures with posterior comminution: a biomechanical study

OBJECTIVES: This study was performed to determine whether four cancellous lag screws provide significantly improved rigidity and fixation strength compared with three screws for fixation of displaced femoral neck fractures with posterior comminution. DESIGN: Biomechanical cadaver study. INTERVENTION: Eight pairs of mildly osteopenic femurs were selected, and each pair was fixed with three or four cancellous lag screws (randomly assigned) after the creation of a simulated femoral neck fracture with posterior comminution. A separate comparison with an unmatched group of six similar femurs with a simulated femoral neck fracture without posterior comminution and instrumented with three screws was performed to investigate the effect of posterior comminution. MAIN OUTCOME MEASUREMENT: The specimens were non-destructively tested to determine fixation rigidity in axial and anterior loading. Cyclic axial loading was then performed for 10,000 cycles; the femurs were retested for rigidity and finally were axially loaded until failure. RESULTS: The femurs with a posterior defect stabilized with three screws had significantly less resistance to axial and anterior displacement and sustained significantly lower axial loads to failure than those stabilized with four screws. The specimens instrumented with three screws without a posterior defect exhibited greater resistance to displacement in anterior loading and sustained greater axial loads to failure than those with a posterior defect stabilized with three screws. CONCLUSION: This study suggests that there are benefits to using four screws for fixation of femoral neck fractures with posterior comminution.     

Surgical treatment of lateral Hoffa fracture with a locking plate through the lateral approach

Objectives

The goal of this study is to determine the efficacy of the surgical treatment of lateral Hoffa fracture with a locking plate and cannulated or lag screws through the lateral approach.

Materials and methods

A total of 12 isolated lateral Hoffa fractures were identified during the study period (February 2005 to February 2010). All fractures were treated by open reduction through the lateral approach. Internal fixation was performed with a contoured locking plate and cannulated or lag screws introduced from the non-weight-bearing area of the cartilage surface of the lateral femoral condyle. Radiological and functional outcome analysis was performed using Knee Society scores.

Results

Bony union of Hoffa fracture was achieved in all patients. The articular surface of lateral femoral condyle was anatomically reduced. There was no loss of reduction and fixation. Functional outcome of knee measurements showed a continuous significant improvement over the follow-up period.

Conclusion

Fixation with a locking plate and cannulated or lag screws for lateral Hoffa fracture seemed to be effective and reliable. The lateral approach had advantages for reduction and fixation of lateral Hoffa fracture during operation.     

Plate fixation for Letenneur type I Hoffa fracture: a biomechanical study

BackgroundA coronal fracture of the posterior femoral condyle, also known as a Hoffa fracture, is an unusual injury, and there are only a handful of case reports or series exploring it. The optimal fixation method of these intraarticular fractures remains controversial; improper or unstable fixation usually lead to an unsatisfactory prognosis. The use of posterior–anterior or reversed lag screw fixation is still a popular method. Additional buttress plating is also recommended for fixation of these difficult fractures. The purpose of this study was to compare the mechanical strength of four different fixation patterns for this uncommon fracture.Material and methodsSixteen sawbone simulated models of Letenneur type I Hoffa fractures were created with one of four fixation patterns: two screws implanted in the anterior–posterior (AP) direction or posterior–anterior (PA) direction; one screw in the PA direction with a plate implanted in the posterior position of the distal femoral condyle or with a plate in the lateral position. Biomechanical testing was performed to determine the post-fixation axial stiffness, the maximum load to failure and the fragment vertical displacement for each of the four constructs.ResultsThe plate fixation patterns whether implanted in the posterior or lateral position were shown to provide higher overall axial stiffness and load to failure, and less vertical displacement than the other two patterns of pure screw fixation. Among these constructs, the lateral plate fixation was found to provide the highest stiffness and load to failure and the least displacement for the posterior condylar fragments, followed by the posterior plate fixation. The lowest overall stiffness and load to failure and the largest vertical displacement were found in the construct with the AP direction placed screws.ConclusionIt was concluded that the lateral position implanted plate is biomechanically the strongest fixation method for Letenneur type I Hoffa fractures. However, this plate fixation is not recommended for all cases. The choice of internal fixation pattern depends on the surgeons.     

Lateral Buttress Plate Along with Cancellous Screw Fixation for Hoffa Fracture Using Swashbuckler Approach

Coronal plane fracture of the posterior femoral condyle, Hoffa fracture is a rare injury pattern. We report a case of a 32-year-old male with closed Lateral Hoffa fracture along with patella and medial condyle of tibia fracture. Patient was treated using 02 cannulated cancellous screws and a lateral recon plate for Hoffa fracture, tension band wiring for patella fracture and 02 cannulated cancellous screws for tibia fracture through modified swashbuckler approach. Twenty-four months postoperatively, the range of movement in the knee was 0°–130°. In this complex case, our technique provided stable fixation of the fragments and a satisfactory final functional outcome.     

Two or three screws for fixation of femoral neck fractures?

This study compares the stability of 3 cannulated cancellous lag screws with that of 2 cannulated cancellous lag screws for fixation of subcapital femoral neck fractures. Using 10 matched pairs of human cadaveric femurs, subcapital femoral neck osteotomies were created, reduced, and then randomized to 1 of the 2 fixation methods. The constructs were tested with anterior loading to 500 N, incremental axial loading from 100 N to 1000 N, and cyclic loading at 1000 N. The specimens stabilized using 3 screws showed greater resistance to anterior loading, less inferior femoral head displacement, and less superior gapping at the osteotomy site. Although 2 screws may be an acceptable fixation method for this fracture type, the addition of a third screw provides supplemental stability and appears justified.     

Hoffa骨折的治疗

目的 总结Hoffa骨折的临床特点,探讨其治疗方法及临床疗效.方法对2002年1月至2009年4月收治的20例24髁Hoffa骨折患者资料进行回顾性分析,男14例18髁,女6例6髁;年龄20～70岁,平均43.3岁.股骨内髁骨折15髁,外髁骨折9髁;其中单侧双髁骨折2例,单侧双髁并对侧单髁骨折1例;新鲜骨折20髁,陈旧性骨折内固定失效4髁.骨折按Letenneur分型:Ⅰ型6髁,Ⅱ型4髁,Ⅲ型14髁.15髁使用从前向后方向2～4枚直径3.5或6.5 mm松质骨螺钉或空心螺钉固定,8髁使用从后向前方向螺钉固定,1髁开放性骨折采用2枚3.0 mm克氏针固定.5髁联合使用侧方支持钢板结合螺钉固定,3髁联合使用后方抗滑移钢板结合螺钉固定.结果 20例患者术后获平均14.4个月(6～84个月)随访.所有患者骨折均获骨性愈介,愈合时间为12～44 周,平均18.6周,无骨折不愈合、感染、内固定松动及股骨髁缺血性坏死等并发症发生.参照Letenneur等的Hoffa骨折术后功能评估标准评定疗效:优16髁,良6髁,差2髁,优良率为91.7%.结论 Hoffa骨折临床少见,螺钉固定是Hoffa骨折于术固定方法的金标准,螺钉固定方向、直径及手术切口的选择应视骨折类型和骨折块大小而定.对于不稳定Hoffa骨折,在螺钉固定的基础上应考虑联合应用侧方支持钢板或后方抗滑移钢板固定.

Abstract：

Objective To investigate clinical characteristics and treatment of Hoffa fractures.Methods Twenty patients with Hoffa fracture (24 condyles) were treated from January 2002 to April 2009.They were 14 men (18 condyles) and 6 women (6 condyles), aged from 20 to 70 years (average, 43. 3 years).There were 15 fractures of medial femoral condyle and 9 ones of lateral femoral condyle. Two rare cases were fractures of unilateral bi-condyles and one rare case fractures of unilateral bi-condyles plus contralateral single condyle. Four fractured condyles were old due to implant failure and 20 were fresh. According to the modified Letenneur's classification, there were 6 condyles of type Ⅰ, 4 condyles of type Ⅱ and 14 condyles of type Ⅲ.Fifteen condyles were fixed anteroposteriorly with 2 to 4 cancellous or canulated screws, 8 condyles were fixed posteroanteriorly with 2 to 4 screws, and one condyle was fixed with K wires. Five condyles were fixed with screws plus lateral supporting plates, and 3 condyles with screws plus posterior anti-sliding plates. Results All the patients were followed up for an average of 14. 4 months (6 to 84 months) . All the 24 condyles obtained bony union after an average of 18. 6 weeks (from 12 to 44 weeks). There was no infection, implant failure, nonunion or bone necrosis. According to Letenneur's functional assessment system, 16 condyles were excellent, 6 good and 2 poor, with a good-to-excellent rate of 91. 7%. Conclusions All Hoffa fractures should be treated with screws. Screw diameter, fixation direction and surgical incision should depend on facture type and size of fracture block. Unstable Hoffa fractures should be treated with screws combined with lateral supporting plates or posterior anti-sliding plates.     

Vertical shear fractures of the femoral neck. A biomechanical study.

A biomechanical cadaver study was performed to compare the strength and stability of three cannulated cancellous lag screws with a sliding hip screw for fixation of a vertically oriented fracture of the femoral neck (Pauwels Type III). Using eight matched pairs of human cadaveric femurs, vertically oriented femoral neck osteotomies were created, reduced, and randomized to one of the two fixation methods. The constructs were tested with incremental axial loading from 100 N to 1200 N and cyclical loading at 1000 N for 10,000 cycles; fracture displacements and ultimate load to failure were determined. The specimens stabilized using a sliding hip screw showed less inferior femoral head displacement, less shearing displacement at the osteotomy site, and a much greater load to failure than did those stabilized with multiple cancellous lag screws. These results support the use of a sliding hip screw for treatment of vertically oriented fractures of the femoral neck.     

Comparison of two headless screw designs for fixation of capitellum fractures

In order to determine the effects of two different headless screw designs on fixation of simulated capitellum fractures six matched pairs of embalmed humeri had simulated capitellum fractures created. Fixation with Acutrac compression screws was compared to Herbert screws in a matched pair experimental design. All specimens were cyclically tested with simulated physiologic loading. Both displacement of the capitellum as a function of the number of cycles and failure loads were determined. Fixation by the Acutrac screws was significantly more stable than Herbert screws at 2000 cycles, 0.17 mm wersus 1.57 mm (p < 0.02) The Acutrac fixation also had a higher failure load, 154 N versus 118 N (p < 0.05). The Acutrac screws tested in this biomechanical study provided more stable fixation of simulated capitellum fractures than Herbert screws. This appears to be related to the design of these screws.     

Undiagnosed Hoffa fracture of medial femoral condyle presenting as chronic pain in a post-polio limb

Isolated coronal fracture of medial femoral condyle with intact lateral femoral condyle is extremely rare. A high index of suspicion is necessary for early diagnosis especially in cases of undisplaced fractures. Here we report a case of medial Hoffa fracture in a post-polio limb presenting as chronic pain. Management of such fractures in limbs affected by late sequelae of poliomyelitis is particularly problematic in view of osteoporosis and osseous hypoplasia. The fracture was approached through medial parapatellar arthrotomy and fixation was done with cannulated cancellous screws in anteroposterior direction. Union was achieved at 16 weeks.     

Coronal fractures of the distal femoral condyle: a biomechanical evaluation of four internal fixation constructs

This study evaluated different fixation methods in posterior femoral condyle coronal fractures. A standardised osteotomy was created in synthetic composite femurs and fixed with one of four methods (one 3.5 mm diameter screw, two 3.5 mm screws, one 6.5 mm screw, two 6.5 mm screws). The stiffness and mean loads to specified displacements were measured. The stiffness of two 6.5 mm screws was significantly greater than both single 3.5 mm screw (3567 versus 2584N/mm; p=0.0075) and double 3.5 mm screws (3567 versus 2080N/mm; p=0.003). There was no statistical difference in the stiffness of one 6.5 mm screw compared to either the single or double 3.5mm screws. Increasing the screw diameter and using two screws increased the load at 1, 2 and 3 mm of displacement. In the fixation of posterior femoral condyle fractures, two 6.5 mm screws are more rigid than either single or double 3.5 mm screws. The use of a second screw marginally increases the rigidity of fixation. If 3.5 mm screws are used in the fixation of posterior femoral condyle fractures, at least two screws should be used to approximate the biomechanical stability of a single 6.5 mm screw.     

The missing piece of the trauma armoury-medial femoral condyle plate

Fixation of distal femoral fractures is often challenging due to the fracture configuration and associated poor bone quality. Dual plating (lateral and medial) has become an acceptable option to provide improved stability versus a single plate fixation.Though there are several commercially available anatomically designed plates for the lateral femoral condyle, there is no anatomic plate available in UK specifically for medial fixation of distal femur fractures.Our aim is to determine the best suited pre-contoured plate for stabilising the medial femoral condyle (MFC).Right sided femur sawbones were used to determine how well 18 different pre-contoured anatomical plates (Depuy Synthes, Leeds, UK) fit the medial femoral condyle. Some of these had variable angle (VA) option. Lift off, fit and notch penetration were assessed and recorded independently by 4 orthopaedic trauma surgeons. The number and distribution of screws in the MFC that each plate allowed was also determined. To do this the MFC was divided into quadrants: Proximal anterior (PA), distal anterior (DA), proximal posterior (PP) and distal posterior (DP).The ipsilateral anterolateral proximal tibial (VA and 4.5 mm non-VA), PHILOS, posteromedial proximal tibial and ipsilateral lateral extra-articular distal humeral plate offered good sagittal fit, less than 2 mm lift off at the condyles and no diaphyseal lift off. Plate positioning in the PA quadrant offered the best fit.The ipsilateral anterolateral proximal tibial plates (VA) and PHILOS allowed at least 4 screws to be placed in the PA and 2 in the PP quadrant with no notch penetration. The Tomofix provided good fit, but all 4 screws were in PA quadrant, with distal screws causing notch penetration. The non-VA and PHILOS plates did not offer the VA advantage.The ipsilateral anterolateral proximal tibial VA plates provided the best anatomical fit for the MFC with the greatest number of screws in the condylar quadrants with the option of variable angle screw placement.     

空心拉力螺钉治疗Hoffa骨折

目的:探讨空心拉力螺钉治疗Hoffa骨折的手术方法及临床疗效。方法:2001年2月至2009年5月采用空心拉力螺钉治疗Hoffa骨折13例,男8例,女5例;年龄23～45岁,平均34.2岁;左侧6例,右侧7例。按Letenneur分型:股骨外髁,Ⅰ型3例,Ⅲ型2例;股骨内髁,Ⅰ型3例,Ⅱ型2例,Ⅲ型3例。根据骨折类型,按不同入路应用松质骨空心拉力螺钉内固定治疗。结果:13例均获随访,时间12～23个月,平均16.5个月。所有患者未发现腘窝动脉、胫神经或腓总神经等并发症。术后半年根据Letenneur膝关节功能评分,优10例,可3例。术后半年X线片示骨折骨性愈合,未发现空心螺纹钉松动、断裂及骨折不愈合等。结论:空心拉力螺钉治疗Hoffa骨折临床疗效满意,手术入路及内固定方式应根据骨折类型、骨折线的位置及骨折块的大小等因素综合判断。     

Isolated Hoffa fracture of the medial femoral condyle in a skeletally immature patient

Intraarticular coronal fracture of the femoral condyle is rare, and an isolated medial Hoffa fracture in a child is extremely rare. To our knowledge, such a case has not yet been reported in the literature. Early diagnosis and prompt treatment are essential for a good long-term outcome. We report a case of 12-year-old male who suffered a traffic accident and sustained an isolated medial Hoffa fracture. Open reduction was performed using a subvastus approach and the joint surface congruity restored and secured by two large fragment partially threaded screws placed from anterior to posterior in the epiphysis. At the 36-month follow-up, the fracture was united, and the patient had full extension and approximately 130° flexion of knee. There was no varus or valgus instability or limb length discrepancy. This case highlights the importance of early diagnosis and prompt treatment in the form of epiphyseal fixation for the management of these fractures in skeletally immature individuals.     

Coronal fractures of the medial femoral condyle: a series of 6 cases and review of literature

Isolated coronal fracture of medial femoral condyle with intact lateral femoral condyle is extremely rare. We present our experience with such 6 cases of coronal fractures of medial femoral condyle. We reviewed all case records of cases of coronal fractures of femoral condyle which presented to our centre from Jan 2000 to Jun 2009. Of 72 such cases, 56 were of lateral condyle, 9 were bicondylar, and 7 were only medial femoral condyle fractures. However, one of the 7 cases was a skeletally immature child with a physeal injury and hence excluded. All the 6 patients with medial femoral condyle fractures were retrospectively evaluated both clinically and radiologically. Of the 6 patients with medial condyle fractures, three patients had an isolated medial femoral condyle fracture, while three of them had associated fractures. Four of these patients were identified at the initial presentation. However, the fracture was missed during initial evaluation in one of the patients, while another patient presented with neglected medial Hoffa fracture after 6 months of injury. Mechanism of injury was direct impact to the medial side of knee in flexion in 4 out of 6 cases. All cases were operated through medial or antero-medial approach, and fixation was achieved in all with antero-posterior screws. All cases united at a mean period of 4.6 months. Coronal fractures of the medial femoral condyle are very rare, and there is a highly likelihood of these fractures being missed by an average orthopaedic surgeon. A high index of suspicion is necessary for early diagnosis especially in cases of undisplaced fractures. Being intra-articular, the ideal management includes open reduction and internal fixation. Medial or antero-medial approach with antero-posterior screws is the preferred method for fixation.     

抗滑动钢板治疗Letenneur Ⅰ型Hoffa骨折的生物力学研究

目的 通过对Letenneur Ⅰ型Hoffa骨折使用抗滑动钢板(使用锁定螺钉和松质骨螺钉两组)与松质骨螺钉(由前向后和由后向前固定两组)四种固定方式固定Letenneur Ⅰ型Hoffa骨折的力学进行比较,探讨抗滑动钢板在Hoffa骨折中的应用.方法 20个模型股骨造成相同的Letenneur Ⅰ型Hoffa骨折,随机分为四组,每组5个.A组使用由前向后两枚松质骨螺钉固定,B组使用由后向前两枚松质骨螺钉固定,C组使用抗滑动钢板加锁定螺钉固定,D组使用抗滑动钢板加松质骨螺钉固定.所有标本通过循环负荷试验和最大失效负荷试验,对最大位移平均值和最大失效负荷平均值进行比较.结果 在循环负荷试验中,第10、100、1000、10 000周期下,四组骨折块最大位移平均值间差异均无统计学意义(P>0.05).而在最大失效负荷试验中,A组[(1224±72)N]和C[(2183±227)N]、D组[(2124±235)N]差异有统计学意义(P<0.05),B组[(1405±235)N]和C、D组差异有统计学意义(P<0.05),A组和B组、c组和D组差异均无统计学意义(P>0.05). 结论对于简单的Hoffa骨折,固定后初期给予适当保护条件,四种固定方式都能取得满意的力学稳定性和强度.但对于预计骨折愈合时间长、体质量指数大、患者依从性差的患者,建议使用抗滑动钢板.     

Coronal fractures of the femoral condyle: a brief report of five cases

Coronal fractures of the femoral condyle (Hoffa fractures) are uncommon injuries that have a better outcome when treated surgically. We report a series of five Hoffa fractures (including one nonunion) treated at a Level 1 trauma center by one surgeon employing a protocol of open reduction and internal fixation with lag screws through a formal parapatellar approach. Postoperatively, all patients began immediate unrestricted range of motion. Initial weight bearing was limited, but all patients were permitted full weight bearing by 10 weeks. All fractures healed within 12 weeks without complications. The final range of motion for the patients with acute fractures was at least 0 degrees to 115 degrees. The patient with a nonunion had a preoperative flexion contracture of 20 degrees and a final range of motion of 20 degrees to 125 degrees. Long-term follow-up (average 37 months, range 18-57 months) was available for 3 of the 5 patients, and Knee Society scores were calculated for these patients (average 173 of 200 points, range 160-180 points). The literature regarding the management of Hoffa fractures is reviewed.     

Open bicondylar Hoffa fracture associated with extensor mechanism injury

Two cases of open bicondylar Hoffa fracture of the knee associated with extensor mechanism injury are described in two active young patients with multiple fractures. The level of the fracture was determined by the proximal insertion of the posterior cruciate ligament and anterior cruciate ligament in the medial and lateral condyle. The level of the extensor mechanism injury was determined by the degree of flexion of the knee at the moment of impact. No ligament or meniscal tears were found. Open reduction and internal fixation with four lag screws and bone-to-tendon repair of the patellar and quadriceps tendon gave excellent results after more than 2 years of follow-up. The mechanism of injury and the therapeutic implications are discussed, and the literature is reviewed.     

股骨髁冠状面骨折的诊断与治疗

目的：探讨股骨髁冠状面骨折的诊断与治疗方法。方法：自2000年3月至2007年10月，对6例股骨髁冠状面骨折采用切开复位空心拉力螺钉固定，术后辅助石膏托外固定，1周后CPM功能锻炼。另1例无移位的股骨外侧髁骨折采用伸膝位石膏固定6周，定期复查x线片。结果：随访6个月～2年，所有患者骨折愈合良好，无骨不愈合及骨坏死发生。膝关节功能按Kumar等拟定的膝关节功能评分系统进行综合评分，优5例，良1例，可1例。结论：空心拉力螺钉加压内固定及伸直位石膏外固定治疗股骨髁冠状面骨折效果良好，值得临床借鉴。     

Delayed posterior internal fixation of unstable pelvic fractures

Fifteen patients with unstable pelvic fractures were treated with immediate anterior external fixation followed by delayed posterior fixation, including five sacroiliac lag screws, six transiliac rods, and four iliac plates. Initial anterior external fixation aided in resuscitation of hemodynamically unstable patients and allowed early mobilization. Delayed posterior internal fixation avoided infection and hemorrhage but failed to achieve anatomic reduction of disrupted sacroiliac joints and sacral fractures. Followup examination confirmed maintenance of fixation and fracture healing but pain and persistent neurologic deficits were common findings. Lumbosacral nerve plexus injuries occurred in patients with fractures through the sacral foramina. Fixation of these fractures with sacroiliac screws and transiliac rods caused overcompression and the resulting foraminal encroachment may be a factor in the lack of neurologic recovery. In this study, delayed posterior internal fixation was not associated with perioperative morbidity and achieved better reductions than those obtained with external fixation alone. Delaying the fixation, however, increased the difficulty of obtaining anatomic reduction of certain posterior arch disruptions.