Influence of stem design on the primary stability of megaprostheses of the proximal femur

Purpose

Extended bone defects of the proximal femur can be reconstructed by megaprostheses for which aseptic loosening constitutes one of the major failure modes. The basic requirement for long-term success of endoprostheses is primary stability. We therefore assessed whether sufficient primary stability can be achieved by four different megaprostheses in a standardised bone defect of the proximal femur and whether their different design leads to different fixation patterns.

Methods

Four different designs of proximal femoral replacements were implanted into 16 Sawbones® after preparing segmental bone defects (AAOS type II). Primary rotational stability was analysed by application of a cyclic torque of ±7 Nm and measuring the relative micromotions between bone and implant at different levels. The main fixation zones and differences of fixation patterns of the stem designs were determined by an analysis of variance.

Results

All four implants exhibited micromotions below 150 μm, indicating adequate primary stability. Lowest micromotions for all designs were located near the femoral isthmus. The extent of primary stability and the global implant fixation pattern differed considerably and could be related to the different design concepts.

Conclusions

All megaprostheses studied provided sufficient primary stability if the fixation conditions of the femoral isthmus were intact. The design characteristics of the different stems largely determined the extent of primary stability and fixation pattern. Understanding these different fixation types could help the surgeon to choose the most suitable implant if the fixation conditions in the isthmus are compromised.     

Sliding bone graft at the distal femur after wide resection for malignant tumor

Objective  Wide resection of a tumor of the distal femur in healthy tissue while sparing the knee joint and preserving function of the limb. Indications  Tumors of the distal femur on the conditions that the distal epiphysis can be preserved for stable anchorage of a condylar blade plate, that limb-sparing surgery is possible and that tumor therapy is curative (expected survival time at least 5 years). Contraindications  Large defects which cannot be bridged by a sliding graft. No possibility for stable anchorage with the condylar blade plate. Generalized tumor disease. Local infections. Surgical Technique  Wide tumor resection through a posterolateral approach. Reconstruction of the defect with a proximal femoral sliding graft, free contralateral fibular transplant and autogenous iliac bone graft. Stabilization of the fragments with screws and a long condylar blade plate. Results  A 20-year-old woman with an osteoblastic osteosarcoma and a 15-year-old boy with a low-grade chondrosarcoma were treated with this technique. In none of the patients a local recurrence or metastasis was observed 9 and 7 years, respectively, after tumor resection. Full weight bearing could be resumed at 6 weeks in the first and at 12 weeks in the second patient. At the latest follow-up, both patients had good to excellent functional results.     

Evaluation of results of open distal femur fractures with primary fixation and antibiotic impregnated collagen

Purpose: Distal femoral fracture is one of the most common lower limb injuries and accounts for less than 1% of all fractures. Open fracture takes 5%e10% of the all distal femoral fractures, which is at an increased risk of complications. There were limited studies which documented the outcomes of such cases. The present study aims to evaluate the outcome and complications in these fractures using primary definitive fixation with condylar locking plate and antibiotic impregnated collagen sheet secondary to aggressive debridement. Methods: This is a prospective study conducted in a tertiary care orthopaedic hospital in northern India. Thirty patients of open distal femoral fractures were managed by primary definitive fixation with condylar locking plate and antibiotic impregnated collagen sheet secondary to aggressive debridement. They were followed for minimum of six months. Patients were followed up monthly for first four months, at six months and one year after surgery. Clinical and radiological signs of healing, any complications, time to union, and functional outcome were assessed. Results: The mean age of patients was 44.33 years (range 20-82 years) with male predominance of 66.7%. According to Gustilo-Anderson classification, there were 5, 15 and 10 patients with open grade I, II and IIIA distal femoral fractures respectively. According to orthopaedic trauma association (OTA) classification, majority of patients in our study were of C3 type. The mean time to bony union was 5.6 months (range 4e9 months). Average postoperative knee range of motion (ROM) at the latest follow-up was 98? (range 70?-120?). Lysholm knee scoring scale showed excellent score in 11 patients, good in 9 patients, fair and poor in 5 patients each; however, there was no significant correlation with fracture pattern types (p < 0.05). Knee stiffness was the major complications encountered in the study. The knee ROM was <90? in 5 patients and 90?-120? in rest of the patients, while 1 patient had extensor lag of 10?. One patient had implant failure and lost to follow-up; 3 patients had deep infection. Conclusion: An approach of primary definitive fixation with condylar locking plate and antibiotic impregnated collagen sheet secondary to early aggressive debridement in open distal femur fractures shows significant results in terms of functional and radiological outcomes with minimal complications.     

Fractures involving the distal epiphyseal plate of the femur

Summary Forty-two fractures involving the distal femoral epiphyseal plate in 41 patients were reviewed. The average age at injury was 11.2 years. The follow up period ranged from one year to 20.3 years, with an average of 6.3 years. The Salter-Harris classification of epiphyseal plate injuries proved to be a good indicator of the mechanism of injury and prognosis. Using stringent criteria to classify the end results, 2 out of 3 of the total group and 3 out of 4 of 29 Salter-Harris Type 1 and Type II injuries had good or excellent results. Type V crushing injuries of the growth plate, open injuries, fractures caused by high velocity motor vehicle accidents with severe displacement or multiple associated fractures, and incompletely reduced epiphyseal injuries gave only poor or fair results. Major problems responsible for poor or fair results were varus or valgus angulation, loss of joint motion and shortening due to premature epiphyseal closure. Orthoradiographs revealed the presence of some degree of shortening in 20 of 29 Salter-Harris Type I and Type II injuries which averaged 1.0 cm, but was of no clinical significance in most patients. These injuries must be reduced accurately. In the Type II epiphyseal separations unsatisfactory results were due to inadequate reduction or to associated injuries.

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Résumé Quarante-deux fractures, chez 41 malades, atteignant le cartilage épiphysaire de l'extrémité inférieure du fémur ont été colligées. L'âge moyen était de 11,2 ans. La période de surveillance a varié de 1 à 20,3 ans, avec une moyenne de 6,3 ans. La classification de Salter et Harris des lésions traumatiques du cartilage de conjugaison s'est avérée un bon indicateur du mécanisme et du pronostic. En utilisant, pour définir les résultats finaux, des critères rigoureux, on a trouvé que 2 patients sur 3 dans l'ensemble, et 3 sur 4 dans les 29 lésions des types I et II, avaient de bons ou d'excellents résultats. Le type V: écrasement du cartilage de conjugaison, les traumatismes ouverts, les fractures liées à des accidents de véhicules à grande vitesse, avec des déplacements importants ou chez les polytraumatisés, et les lésions épiphysaires incomplètement réduites, ont seuls donné des résultats médiocres ou mauvais. Les éléments principaux, facteurs de ces mauvais résultats, sont les désaxations en varus ou en valgus, la perte de la mobilité articulaire et le raccourcissement dû à une épiphysiodèse prématurée. Les orthoradiographies ont montré l'existence d'un certain degré de raccourcissement dans 20 des 29 types I et II, de l'ordre d'un cm, mais sans traduction clinique dans la majorité des cas. Ces lésions doivent être réduites avec précision. Dans le type II, les résultats insuffisants sont dus à une réduction incomplète ou à l'existence de traumatismes associés.

     

A double-plating approach to distal femur fracture: A clinical study

BackgroundLocked plating is one of the latest innovative options for treating supracondylar femur fractures with relatively low failure rates. Single lateral plating was often found to have a relative higher failure rate. No clinical studies of double-plating distal femur fixation have thus far been reported. The aim of this study is to present our clinical experience with this surgical approach.Patients and methodsThirty-two patients (26 females and 6 males, mean age 76 years, range 44–101) were included in the study. Eight of them patients had a periprosthetic stable implant fracture and two patients were treated for a nonunion.ResultsAll fractures, excluding one that needed bone grafting and one refracture, healed within 12 weeks. One patient needed bone grafting for delayed union and one patient needed fixation exchange due to femur re-fracture at the site of the most proximal screw. Two patients developed superficial wound infection and one patient required medial plate removal after union due to deep infection.ConclusionsBased on these promising results, we propose that the double-plating technique should be considered in the surgeon’s armamentarium for the treatment of supracondylar femur fractures, particularly in patients with poor bone quality, comminuted fractures and very low periprosthetic fractures.     

Injuries to the distal femur and patella

Injuries around the knee are often high-energy injuries. The anatomy of the distal femoral physis contributes to its stability and hence high energy is required for disruption of this physis. As the distal femur contributes to the majority of the growth of the lower limb, injury to this growth plate has a high incidence of growth disturbance. Supracondylar femoral fractures can be difficult to reduce and fix due to the short metaphyseal segment. Patellar dislocations are commonly seen in adolescents. Patellar fractures are the result of direct or indirect trauma in children. These can be associated with osteochondral fragments and sleeve fractures often seen in children. Mechanisms of injury, associated anatomy and management options for distal femoral fractures, distal femoral physeal injuries and patella injuries are discussed in this article.     

动力髁螺钉内固定并一期植骨治疗股骨远端严重粉碎骨折

目的探讨股骨远端严重粉碎骨折的治疗方法。方法应用动力髁螺钉(dynamic condylar scrow，DCS)内固定并一期植骨治疗股骨远端严重粉碎骨折21例，对术后膝关节功能进行评价。结果21例病人均获随访，膝关节功能：优7例、良9例、可4例、差1例，优良率近80％。结论动力髁螺钉内固定并一期植骨是治疗股骨远端严重粉碎骨折的一种有效方法。     

股骨下段恶性骨肿瘤保肢术后中期肿瘤学预后及假体功能评估

目的明确股骨下段恶性骨肿瘤保肢术后的中期肿瘤学预后,评估患肢功能状况及相关影响因素。方法回顾性分析2000年1月至2007年1月行股骨下段恶性骨肿瘤瘤段切除、膝关节肿瘤假体置换术的54例中获得随访的37例患者,男21例,女16例;年龄14～65岁,平均31.0岁。术后随访肿瘤学预后、患肢功能及两者的相关影响因素。功能评分采用1993年美国骨肿瘤学会评分系统（MSTS）,并对功能评分采用t检验或秩和检验进行单因素比较。结果37例获得随访,随访时间2～9年,平均49.4个月。随访中存活26例（70.3%）,其中无瘤生存24例（64.9%）,带瘤生存2例（5.4%）;局部复发4例（10.8%）,截肢3例（8.1%）。其中18例骨肉瘤患者的总生存率为66.7%（12/18）,其五年、七年生存率均为59.83%;24例ⅡB期肿瘤患者的总生存率为58.3%（14/24）,其五年、七年生存率均为50.97%;24例ⅡB期肿瘤患者的中期肿瘤学预后较非ⅡB期肿瘤患者差（P=0.0215）。24例存活且未截肢患者的MSTS得分为（26.3±3.0）分,功能优秀率为87.5%;股骨下段恶性肿瘤患者中无病理性骨折患者保肢术后功能得分为（27.1±2.4）分,优于有病理性骨折患者的（23.8±3.5）分（P=0.027）。结论股骨下段恶性骨肿瘤假体保肢术具有较好的肿瘤学预后和术后功能;影响股骨肿瘤膝关节保肢术肿瘤学预后的重要因素是肿瘤的Enneking分期及肿瘤对化疗的敏感程度;导致股骨肿瘤膝关节MSTS功能评分的危险因素是术前病理性骨折,患者年龄、股骨截骨长度和肿瘤假体类型对术后功能无影响。     

拉力螺丝钉配合动力髁螺钉系统治疗股骨远端粉碎性骨折

目的总结拉力螺丝钉配合动力髁螺钉系统(DCS)治疗股骨远端粉碎性骨折的临床效果。方法26例股骨远端粉碎性骨折采用动力髁螺钉系统及拉力螺丝钉内固定,股骨髁间用2～3枚松质骨螺丝做拉力固定,较小骨折块用拉力螺丝钉固定在较大的骨折块上。骨折按AO/ASIF分类:A3型2例,C1型6例,C2型13例,C3型5例。结果平均随访14个月,25例骨折正常愈合,1例延迟愈合,平均骨折愈合时间为5.6个月;按Kolmenrt评定标准:本组优17例,良6例,一般2例,差1例,优良率88.5%。膝关节活动度55°～120°,平均膝关节活动度98.6°。结论拉力螺丝钉配合动力髁螺钉系统可有效治疗股骨远端粉碎性骨折,具有固定牢固、骨折愈合率高、并发症少等优点。     

经关节入路微创钢板固定技术治疗股骨远端C型骨折

目的探讨经关节入路微创钢板固定(MIPPO)技术治疗股骨远端C型骨折的临床疗效。方法2002年4月～2005年2月,应用MIPPO技术治疗股骨远端C型骨折14例,按AO/ASIF分类：C1型3例,C2型6例,C3型5例。先行关节内骨折切开复位、松质骨螺钉固定,再行髁上部分骨折间接复位、经关节内切口插入髁支撑钢板或LISS钢板桥接固定骨折。结果12例患者获得10～32个月(平均18．4个月)随访,骨折均获愈合,愈合时间10周～12个月,平均4．6个月。按Kolmert和Wulff的评价标准：优4例,良5例,可2例,差1例,优良率为75%。结论应用MIPPO技术治疗股骨远端C型骨折实现了微创操作,具有创伤小、软组织干扰少、骨折愈合快等优点,疗效满意。     

Fatigue fracture of the distal femur arising in the elderly

Fatigue fractures most frequently involve the tibia and metatarsal bones in the young. We report a very unusual case of fatigue fracture in the distal femur of a 62-year-old man. The differential diagnosis was a pathological fracture due to a metastatic bone tumor. The diagnosis of fatigue fracture was based on the fact that the patient walked every day for a long time, together with the following radiological features: no definite cortical destruction, a radiolucent area surrounded by sclerosis on CT, no extraskeletal mass, and sharp linear low signal intensities in the center of the lesion on MR images. Rest and restricted walking improved his symptoms and fracture healing. Fatigue fracture should be ruled out even in the elderly, especially those who engage in sports activities for long periods.     

Treatment of open intraarticular distal femur fractures by Ilizarov fixator; an approach to improve the outcome with mid-term results

PurposeOpen comminuted intraarticular distal femur fracture represents a formidable challenge for the orthopaedic surgeon for the inherent fracture complexity, soft tissue damage, and contamination. The purpose of this study was to evaluate the mid-term outcome results and safety of using the Ilizarov fixator to treat these fractures.Patients and MethodsThe study included 22 fractures treated by debridement with reduction and stabilization by Ilizarov external fixator. The mean age was 35 years. Gustilo grade of open fracture was III-A (19 cases), III-B (2 cases), and III-C (1 case). Six fractures were AO-OTA type 33C2, and 16 cases were type 33C3. Eight patients had associated injuries. Bone and functional results were evaluated by Association for the Study and Application of the Method of Ilizarov (ASAMI) criteria, and Neer knee score. The statistical analysis was done using the IBM SPSS Statistics for Windows.ResultsSeven cases had autogenous bone grafting. The frame crossed the knee in 8 patients. The fixator was removed after a mean of 7 months with union in all cases, and without any malalignment >5°. Deep infection occurred in two cases. Quadriceps-plasty was needed for 3 cases. After a mean of 44 months, the last follow-up results showed full knee extension and a mean flexion of 107.59°. The ASAMI functional and bone results were good to excellent in all cases. Neer knee score averaged 86.59.ConclusionsIlizarov fixator was an effective treatment modality of open comminuted distal femur fractures with high union rate, adequate alignment and satisfactory functional outcomes.     

切开复位解剖钢板内固定治疗股骨远端复杂骨折

目的探讨采用切开复位解剖钢板内固定治疗股骨远端复杂骨折的临床疗效。方法2001年1月～2004年6月采用切开复位解剖钢板内固定治疗股骨远端复杂骨折患者67例，25例C3型骨折选用股骨髁上支持钢板，42例A3、c2型骨折选用股骨远端接骨板；其中35例自体髂骨植骨，23例同种异体骨植骨，9例腓骨髓内植骨＋髂骨植骨；全部患者在股四头肌与股骨之间应用生物可吸收医用膜；13例辅助髌骨牵引。术后常规中药熏洗、CPM锻炼等综合方法治疗。结果67例患者获得10．26个月（平均15个月）随访，骨折均获愈合，膝关节功能按Kolment标准评定：优36例，良23例，可5例，差3例，优良率为88．1％。结论切开复位解剖钢板内固定治疗股骨远端复杂骨折，固定可靠，可满足膝关节早期功能锻炼，有效防止股四头肌粘连和膝关节僵硬。辅助局部一期植骨、应用生物可吸收医用膜，部分髌骨牵引、术后中药熏洗、CPM锻炼等综合方法可获得满意疗效。     

Treatment of distal femur fractures in a regional Australian hospital

AIM:To review our outcomes and compare the results of the Less Invasive Stabilization System(LISS)to other implants for distal femur fracture management at a regional Australian hospital.METHODS:The LISS is a novel implant for the management of distal femur fractures.It is,however,technically demanding and treatment results have not yet been assessed outside tertiary centres.Twenty-seven patients with 28 distal femur fractures who had been managed surgically at the Mackay Base Hospital from January 2004 to December 2010 were retrospectively enrolled and assessed clinically and radiologically.Outcomes were union,pain,Lysholm score,knee range of motion,and complication rates.RESULTS:Twenty fractures were managed with the LISS and eight fractures were managed with alternative implants.Analysis of the surgical techniques re-vealed that 11 fractures managed with the LISS were performed according to the recommended principles(LISS-R)and 9 were not(LISS-N).Union occurred in67.9%of fractures overall:9/11(82%)in the LISS-R group vs 5/9(56%)in the LISS-N group and 5/8(62.5%)in the alternative implant group.There was no statistically significant difference between pain,Lysholm score,and complication rates between the groups.However,there was a trend towards the LISS-R group having superior outcomes which were clinically significant.There was a statistically significant greater range of median knee flexion in the LISS-R group with compared to the LISS-N group(P=0.0143)and compared with the alternative implant group(P=0.0454).CONCLUSION:The trends towards the benefits of the LISS procedure when correctly applied would suggest that not only should the LISS procedure be performed for distal femur fractures,but the correct principle of insertion is important in improving the patient’s outcome.     

Low-grade central osteosarcoma of distal femur,resembling fibrous dysplasia

We report a case of a 32 year-old male, admitted for a lytic lesion of the distal femur. One month after the first X-ray, clinical and imaging deterioration was evident. Open biopsy revealed fibrous dysplasia. Three months later, the lytic lesion had spread to the whole distal third of the femur reaching the articular cartilage. The malignant clinical and imaging features necessitated excision of the lesion and reconstruction with a custom-made total knee arthroplasty. Intra-operatively, no obvious soft tissue infiltration was evident. Nevertheless, an excision of the distal 15.5 cm of the femur including 3.0 cm of the surrounding muscles was finally performed. The histological examination of the excised specimen revealed central low-grade osteosarcoma. Based on the morphological features of the excised tumor, allied to the clinical findings, the diagnosis of low-grade central osteosarcoma was finally made although characters of a fibrous dysplasia were apparent. Central low-grade osteosarcoma is a rare, well-differentiated sub-type of osteosarcoma, with clinical, imaging, and histological features similar to benign tumours. Thus, initial misdiagnosis is usual with the condition commonly mistaken for fibrous dysplasia. Central low-grade osteosarcoma is usually treated with surgery alone, with rare cases of distal metastases. However, regional recurrence is quite frequent after close margin excision.     

Results in treatment of distal femur fractures using polyaxial locking plate

Indications and techniques of locked plate fixation for the treatment of challenging fractures continue to evolve. As design variant of classic locked plates, the polyaxial locked plate has the ability to alter the screw angle and thereby, enhance fracture fixation. The aim of this observational study was to evaluate clinical and radiographic results in 89 patients with 90 fractures of the distal femur treated, between June 2006 and November 2011, with such a polyaxial locked plating system (Polyax™ Locked Plating System, DePuy, Warsaw, IN, USA). Seventy-seven fractures formed the report of this study. These cases were followed up until complete fracture healing or for a mean time of 77 weeks. At the time of last follow-up, 58 of 77 fractures (75.3 %) progressed to union without complication and radiographic healing occurred at a mean time of 16.3 weeks. Complications occurred in ten fractures that did not affect the healing and in nine fractures that showed delayed or non-union. The mean American Knee Society Score at the time of final follow-up was 83 for the Knee Score and 71.1 for the Functional Score. In conclusion, there is a high union rate for complex distal femoral fractures associated with a good clinical outcome in this series.     

Working length and proximal screw constructs in plate osteosynthesis of distal femur fractures

BackgroundThe study purpose is to evaluate the working length, proximal screw density, and diaphyseal fixation mode and the correlation to fracture union after locking plate osteosynthesis of distal femoral fractures using bridge-plating technique.MethodsA four-year retrospective review was performed to identify patients undergoing operative fixation of distal femur fractures with a distal femoral locking plate using bridge-plating technique for the metadiaphyseal region. Primary variables included fracture union, secondary surgery for union, plate working length, and diaphyseal screw technique and configuration. Multiple secondary variables including plate metallurgy and coronal plane fracture alignment were also collected.ResultsNinety-six patients with distal femur fractures with a mean age 60 years met inclusion criteria. None of the clinical parameters were statistically significant indicators of union. Likewise, none of the following surgical technique parameters were associated with fracture union: plate metallurgy, the mean working length, screw density and number of proximal screws and screw cortices. However, diaphyseal screw technique did show statistical significance. Hybrid technique had a statistically significant higher chance of union when compared to locking (p = 0.02). All proximal locking screw constructs were 2.9 times more likely to lead to nonunion.ConclusionsPlating constructs with all locking screws used in the diaphysis when bridge-plating distal femur locking plates were 2.9 times more likely to incur a nonunion. However, other factors associated with more flexible fixation constructs such as increased working length, decreased proximal screw number, and decreased proximal screw density were not significantly associated with union in this study.     

解剖型钢板植骨术治疗股骨下端复杂粉碎骨折

目的总结股骨下端复杂粉碎骨折解剖型钢板植骨固定的临床特点、效果。方法20例患者按AO分类，C2型11例，C3型9例，合并髌骨骨折7例。解剖型钢板固定的同时根据骨缺损情况行髂骨、腓骨植骨，观察疗效。结果所有患者随访10～24个月，骨折全部愈合，按schatzker的疗效评定标准，优14例，良5例，可1例，优良率95％。结论解剖型钢板植骨术是治疗股骨下端C2、C3型骨折的理想方法。     

The longitudinal split technique for narrow canal tibia in a case of distal femur replacement for osteosarcoma

IntroductionThere are currently no available prostheses that can be used for extremely small femurs or tibias of adult patients in countries where allograft is unavailable.Case reportWe report the case of a 17-year-old girl requiring special limb salvage technique for distal femur reconstruction following resection of malignant tumor. This technique was needed because of a very narrow canal of the tibia. We split bilateral tibial cortices longitudinally with osteotomies to enlarge tibial canal enough to insert conventional endoprosthesis. After insertion of the implant, split tibia reduced with titanium cables and bands, and the split clefts were filled with cancellous bone. Fifteen months after the operation, proper fixation was achieved with bony fusion of bilateral split clefts and ambulation without assistance was achieved.DiscussionAny proper surgical procedure for our patient were reported previously. We developed a conventional non-expandable endoprosthesis for distal femur replacement using the double longitudinal split technique as a solution to this difficult problem.ConclusionOur longitudinal split technique should be applicable to adult patients with skeletal immaturity requiring resection of juxta-articular malignant tumors and in other situations complicated by the presence of a narrow canal.     

Treatment of fixed knee flexion deformity and crouch gait using distal femur extension osteotomy in cerebral palsy

Purpose

The purpose of this study was to evaluate the results of distal femur extension osteotomy and medial hamstring lengthening in the treatment of fixed knee flexion deformity in patients with spastic diparetic cerebral palsy.

Methods

A retrospective study was done in a group of 12 diparetic cerebral palsy patients. A distal femur extension osteotomy was performed as part of multilevel surgery on lower limbs. The fixed knee flexion deformity was measured during physical examination, whereas hip and knee flexion in the stance phase and anterior pelvic tilt were both analyzed at kinematics. The pre- and post-surgery results were compared and analyzed statistically. A medical record review was done in order to identify the complications. The mean follow-up was 28 months.

Results

A significant reduction of fixed knee flexion deformity at physical examination and knee flexion in the stance phase at kinematics was observed, but with no decrease in hip flexion. As a non-desired effect, there was an increase in anterior pelvic tilt after surgical procedures. With regard to complications, a single patient had skin breakdown at a calcaneous area on one side and the recurrence of deformity was seen in 27% of cases.

Conclusions

In this study, in which fixed knee flexion deformity did not exceed 40° before surgery, the distal femur extension osteotomy was effective in increasing knee extension in the stance phase. However, an increase in anterior pelvic tilt, deformity recurrence and necessity for walking aids are possible complications of this procedure.