Cemented internal fixation for supracondylar femur fractures in osteoporotic patients

Outcome of the Masquelet Technique for Complex Bilateral Distal Femoral Bone Defects

Bone defects are severe conditions caused by various etiologies, including trauma, tumor resection, or chronic osteomyelitis. Different surgical interventions can be utilized to manage such cases, including autologous graft or allograft implantation, distraction osteogenesis, acute shortening, amputation, or the induced membrane technique. Herein, the case of a 39-year-old woman with complex bilateral distal femoral fractures with intra-articular extension is presented. The fractures were accompanied by a significant metaphyseal bone defect, which was managed successfully using the induced membrane Masquelet technique. The patient fully healed despite residual knee joint contractures that did not inhibit her mobility. In conclusion, the Masquelet technique successfully manages complex bone defects and restores functionality even in bilateral simultaneous open bone defects.

Osteoporotic Distal Fibula Fractures in the Elderly: How To Fix Them

Osteoporotic fractures of the distal fibula in elderly patients is a challenge to manage. Non-operative management has a poor outcome so operative management is preferred. There are a variety of options for operative management such as locked plate systems, anti-glide plate construct, dual plating constructs, fibula nail, plate with tibial pro-fibular screws, and injectable bone cement (polymethylmethacrylate (PMMA), calcium phosphate). However, no clear guidelines exist for the operative management of osteoporotic distal fibula fractures. The surgeon should detect osteoporotic fractures early to make the best use of resources and avoid complications such as implant failure.

Outcomes of distal femoral fractures treated with minimally invasive plate osteosynthesis versus open reduction internal fixation with combined locking plate and interfragmentary screws

PURPOSE

Fractures of the distal femur remain challenging to treat, and numerous fixation methods are designed to promote stability and fracture healing. Locking plate constructs have recently become the mainstream fixation method, but debate exists on whether to use locking plates alone or to augment them with interfragmentary screws. This article compares outcomes of distal femur fractures treated with a single locking plate alone versus those treated with a locking plate and interfragmentary screws.

METHODS

We retrospectively reviewed 57 patients treated for distal femur fractures from 2010 to 2013. Patients were divided into two groups: Those treated with a locking plate alone utilizing the minimally invasive plate osteosynthesis (MIPO) technique and those treated with combination of a locking plate and interfragmentary screws using an open technique. Postoperative outcomes were obtained via a manual chart review. Fracture healing and callus indices were evaluated from radiographs.

RESULTS

9 patients required revision surgery in the locking plate alone group (6 for persistent nonunion and 3 for varus deformity). Only two patients in the combination group required revisions (both for nonunion). Average time to full weight bearing was 19.54 weeks in the locking plate group versus 14.57 weeks in the combination group (p = 0.004). At the time of full weight bearing, frontal (1.15 versus 1.11, p = 0.004) and sagittal (1.22 versus 1.15, P = 0.008) callus indices were both significantly greater in the locking plate group.

CONCLUSIONS

In this study, the combination of a locking plate and interfragmentary screws achieved suitable stability and a faster time to full weight bearing than using a locking plate alone. Surgeons should consider combining a locking plate with interfragmentary screws as an effective method for fixation of distal femur fractures, particularly in cases when plate fixation alone fails to provide adequate fracture stability.

Primary total knee arthroplasty for complex supracondylar femoral fractures in patients with knee arthritis: A retrospective study of a patient cohort

When elder arthritis patients suffered from complex supracondylar femoral fractures, their joints condition and general health condition elevate the difficulties in operation and post-surgical recovery.Here, we aimed to simplify the operation procedure by using one-step Total Knee Arthroplasty (TKA) with a stemmed femoral implant. We also investigated if this method could improve the patients' experience after the operation. The surgery including femoral osteotomy and implantation was performed on all fourteen patients by the same orthopedic specialist. The patients' hospitalization time was recorded. The recovery of knee function and patient satisfaction was evaluated by a systematic follow-up with average time 38 months, up to 5 5 years, using Hospital for Special Surgery (HSS) knee scores, the range of motion (ROM), anteroposterior and lateral radiography, and Visual Analog Scale (VAS) scores. The average of hospitalization days was 16 days. No angular deformity, malunion, or shortening were found at radiography.The average ROM was 105.2° at the end of the follow-up period. The knees in all the patients show adequate stability. All patients had returned to their former daily activities. Seventeen out of 24 patients were satisfied with the outcome of the surgery.The usage of TKA with a stemmed femoral implant is a reasonable method for elderly patients suffering from supracondylar femoral fractures and concomitant knee arthritis.

Double plating of intra-articular multifragmentary C3-type distal femoral fractures through the anterior approach

INTRODUCTION

In this prospective case series, we report a mean of 12-month follow-up of the utilization of a dual plating of distal femoral fractures. Our technique included a lateral distal femoral locked plate with a low-contact-locked medial plate and bone graft through an extended medial parapatellar anterior approach for the fixation of C3-type distal femoral fractures.

PATIENTS AND METHODS

Sixteen patients (11 males and 5 females) presented with supracondylar femoral fracture type C3, according to Müller long-bone classification system and its revision OA/OTA classification. These were treated using dual plating through extended anterior approach and bone grafting. Our outcomes included clinical and radiological outcomes. Secondary outcomes included postoperative complications.

RESULTS

The mean time of complete radiological union in the studied population was 6.0 ± 3.5 months with a range of 3-14 months. We have not observed postoperative varus or valgus deformity in our cohort. The majority (68.75%) of the studied patients showed significant improvement in range of motion (90°-120°) during follow-up. Eleven out of sixteen patients (68.75%) had well-to-excellent functional outcome. Poor outcome was reported in only two patients (12.50%).

CONCLUSIONS

Dual plating fixation using anterior approach for type C3 distal femoral fractures is an efficient method of management. It has several advantages such as precise exposure, easy manipulation, anatomical reduction and stable fixation. However, operative indications and instructions should be strictly followed. The surgical technique must be rigorous, and the biomechanical qualities of these implants must be understood to prevent the development of major complications.

Open Reduction vs Distal Femoral Replacement Arthroplasty for Comminuted Distal Femur Fractures in the Patients 70 Years and Older

BACKGROUND

The ideal management of distal femur fractures in the elderly is unclear. Acute arthroplasty has the theoretical advantage of earlier mobilization. We examined the outcomes of patients 70 years and older who underwent open reduction internal fixation (ORIF) vs distal femoral replacement (DFR) for comminuted, intra-articular distal femur fractures.

METHODS

A retrospective review of patients with AO/OTA classification 33C distal femur fractures treated with either ORIF or DFR was performed. Outcomes including all-cause reoperation, length of stay, fracture union, postoperative complications, use of ambulatory device and living situation at 1 year, and mortality were evaluated.

RESULTS

The study cohort included 38 patients: 10 underwent DFR and 28 ORIF. Mean patient age for both cohorts was 82 years. No difference in comorbidities or mechanism of injury was found between groups. The incidence of reoperation was 11% in the ORIF group and 10% in the DFR group. In the ORIF group, the average time to fracture union was 24 weeks, with a nonunion incidence of 18%. Twenty-three percent of ORIF group were wheelchair dependent vs none in the DFR cohort, although not statistically significant. Differences between the groups with respect to all-cause reoperation, living situation or need for ambulatory device at 1 year, and 1-year mortality did not reach statistical significance.

CONCLUSION

Nearly 1 in 5 patients older than 70 years developed a nonunion after ORIF of an intra-articular distal femur fracture. At 1-year follow-up, all patients in DFR group were ambulatory while 1 in 4 in the ORIF group were wheelchair bound.

Commentary on the primary stability of three different iliosacral screw fixation techniques in osteoporotic cadaver specimens-a biomechanical investigation

Oberkircher L, Masaeli A, Bliemel C, Debus F, Ruchholtz S, Krüger A. Primary stability of three different iliosacral screw fixation techniques in osteoporotic cadaver specimens-a biomechanical investigation. Spine J 2016:16:225-31 (in this issue).

Periprosthetic fractures around total knee arthroplasty

Periprosthetic fractures around total knee replacements were first reported more than 30 years ago. They are becoming more common. Various associated risk factors have been described. Treatment options for femoral fractures around total knee replacements include non-operative management, locked plates, retrograde intramedullary nails and revision arthroplasty. Periprosthetic fractures of the tibia and patella are also described, but are less common. This review article provides an overview of the epidemiology and frequency of periprosthetic fractures around total knee replacement, their initial assessment and the current treatment options available.

Osteoporotic ankle fractures: an approach to operative management

The incidence of osteoporosis is increasing as the elderly population grows. Because these patients remain active, fragility fractures of the ankle are becoming more common. The literature indicates a relatively high complication rate for non-operative management of ankle fractures in this patient cohort, leading surgeons to face challenges unique to patients with poor bone and skin quality. This article discusses techniques to address osteoporotic ankle fractures and reviews the current literature relevant to this issue.

Osteoporotic ankle fractures

Ankle fractures are one of the most common injuries in the elderly and their incidence is anticipated to increase over the next 20 years. Appropriate management of ankle fractures in this population requires an understanding of the issues unique to the elderly. Osteoporosis must be considered when counseling patients about their ankle fracture. Good outcomes can be achieved with surgical fixation of ankle fractures in the elderly. Postoperative complications are higher in patients with diabetes and peripheral vascular disease, and in patients who smoke. This article reviews how to evaluate and treat ankle fractures in elderly patients with osteoporosis, evaluates the outcomes, and discusses surgical techniques.

A three-dimensional comparison of intramedullary nail constructs for osteopenic supracondylar femur fractures

OBJECTIVES

This study developed a new 6 degree-of-freedom, unconstrained biomechanical model that replicated the in vivo loading environment of femoral fractures. The objective of this study was to determine whether various distal fixation strategies alter failure mechanisms and/or offer mechanical advantages when performing retrograde intramedullary nail (IMN) stabilization of supracondylar femur fractures in osteoporotic bone.

METHODS

Forty fresh-frozen human femora were allocated into 2 groups of matched pairs: "locked" (fixed angle locking construct with both distal locking screws rigidly attached to the IMN) versus "unlocked" (conventional locking technique with 2 distal locking screws targeted through the distal locking screw holes of the IMN) and "locked" versus "washer" (fixed angle locking with the most distal screw exchanged for a bolt with condyle washers) distal fixation of a retrograde IM nails. A comminuted fracture (OTA 33-A3) was simulated with a wedge osteotomy. Bone density measurements were completed on all specimens before instrumentation. Instrumented femurs were loaded axially to failure, whereas 6 degree-of-freedom translations and angulations were measured using Roentgen stereophotogrammetric analysis.

RESULTS

Mean (± SD) load born by "locked" specimens (1609 ± 667 N) at clinical failure was 38.1% greater (P = 0.09) than the corresponding mean load born by "unlocked" specimens (1165 ± 772 N). Clinical failure for the "washer" group (1738 ± 772 N) was 29.9% greater (P = 0.07) than the corresponding mean of the "locked" counterparts (1338 ± 822 N). Failure load was most clearly related to bone density in the "unlocked" fixation group.

CONCLUSIONS

Predicting failure load based on bone density using a least squares estimate suggests that the washer construct provides superior fixation to other treatment techniques. The failure mechanism for a comminuted, supracondylar fracture cannot be analyzed accurately with a 1-dimensional measurement. The most common failure mechanism in this model was medial translation and varus angulation.

A New System to Improve Screw Fixation to Bones

Plates and non-locked screws used in the treatment of osteoporotic bone fractures frequently become loose due to everyday mechanical demands. Currently, locking plates and screws are the gold standard treatment for these fractures. However, their use has several limitations and complications as they are technically demanding, and their cost is very expensive. To improve the fixation strength of traditional unlocked plate and screw constructs, we have developed a new fixation system based on a very old concept. The system consists of a screw locking element (SLE) manufactured from PEEK, which is attached to the end of the screw shaft once it has traversed both bone cortices. A specially designed tool is used to facilitate its attachment to the screw. This tool makes it possible for the screw to traverse an osteosynthesis plate or lockwasher as well as both bone cortices and to easily find the SLE, fixing it against the far cortex. We tested the pull-out strength of SLEs and compared the results with previously published data for human femoral cortex pull-out strength. Our laboratory tests demonstrate that the mean SLE pull-out strength was 3864 ± 47.61 N, while that observed for a human femoral diaphysis cortex was 4071.54 ± 1461.69 N. This difference was not significant (p > 0.05). This new system can easily be used with any type of osteosynthesis in osteoporotic or osteopenic bones, with the screws being placed on weakened areas of the bone (e.g., fissure lines, previous orifices, or thinned metaphyseal bone cortex), or to replace over-torqued screws. It is particularly suitable for veterinary trauma, where immediate weight-bearing protection after fracture treatment is nearly impossible.

Primary total knee arthroplasty in the management of epiphyseal fracture around the knee

INTRODUCTION

Over the past few years the use of arthroplasty was broadened to treating complex epiphyseal fractures at the shoulder and elbow joints. Similar trends to treat this type of fractures at the knee are less documented. Based on a multicenter retrospective series study, the aims of this work is to evaluate the short term clinical results of total knee prostheses in the management of comminuted epiphyseal fractures around the knee, to identify the technical issues and fine tune the indications.

MATERIAL AND METHODS

Following the initiative of the French Hip and Knee Society (SFHG) and the Traumatology Study Group (GETRAUM), 26 charts from eight different centers in France were included in this multicenter retrospective series. Inclusion criteria were: primary total knee arthroplasty (TKA) in the management of complex articular fractures involving the proximal end of the tibia or distal end of the femur. Surgical features were identified and complications were analyzed. The assessment protocol at last follow-up was standardized and included patient demographic data, analysis of the Parker and IKS scores.

RESULTS

During the immediate postoperative period, six patients (23%) reported a general complication and four patients (15%) a local arthroplasty-related complication. At last follow-up (mean 16.2 months), the overall final Parker score was 6.3 (a mean decrease of 1.7) and the mean IKS knee score was 82 points for a mean function score of 54 points.

DISCUSSION

Primary TKA is a suitable management option for complex fractures in autonomous elderly patients suffering from knee osteoarthritis. The key technical details of this procedure should be respected and meticulously planned to achieve optimal results and limit the risk of complications. This risk in these acute complex fractures remains higher than after conventional TKA but comparable to that observed after TKA for post-traumatic arthritis.

LEVEL OF EVIDENCE

IV; retrospective cohort study.

Nailed cementoplasty: a salvage technique for rorabeck type II periprosthetic fractures in octogenarians

Periprosthetic femoral fractures around a total knee arthroplasty present a surgical challenge in octogenarians with advanced osteoporosis. We describe a salvage technique combining retrograde intramedullary nailing augmented with polymethylmethacrylate cement in 5 patients followed up for a median time of 12 months. The nail/cement construct bridges the femoral canal tightly and simulates a stemmed cemented revision component. All patients had an uncomplicated recovery and returned to their preinjury functional status within 4 months. This procedure does not disrupt the soft tissue envelope around the fracture site, is easy to perform and permits immediate full range of movement. When standard retrograde nailing or plating alone is inadequate in maintaining severely osteoporotic fracture reduction, nailed cementoplasty is proposed as a salvage procedure in octogenarians unfit for lengthy interventions.

Treatment of distal femoral fracture by minimally invasive percutaneous plate osteosynthesis: comparison between the dynamic condylar screw and the less invasive stabilization system

BACKGROUND

Treatment of distal femoral fractures by percutaneous plating without direct manipulation of the fracture fragments leads to good clinical outcome. Percutaneous plating has traditionally involved using a dynamic condylar screw (DCS) and the less invasive stabilization system (LISS) was reported. The biomechanical study showed that the LISS had the enhanced ability to withstand higher loads. However, there were no clinical comparison study of distal femoral fractures treated with DCS and LISS. The aim of this study was to outline any differences in clinical and radiological results between the DCS and the LISS for treating distal femoral fractures.

METHODS

Forty-five supracondylar or intercondylar femoral fractures were treated by minimally invasive percutaneous plating with the DCS or the LISS without bone graft. There were 26 patients with 26 fractures in the DCS group and 19 patients with 19 fractures in the LISS group. The data of the clinical and radiographic outcomes were compared between the two different fixation devices.

RESULTS

Complete union was achieved in 41 of the 45 patients (91.1%). The success rate was 96.2% in the DCS group and 94.7% in the LISS group (p = 0.672). The mean fusion time was 19.18 weeks in the DCS group and 19.38 weeks in the LISS group (p = 0.835). The average range of motion of the knee joint was 111.65 degrees in the DCS group and 116.26 degrees in the LISS group (p = 0.334). Early implant failure only occurred in the DCS group (11.5%, p = 0.252, odds ratio = 1.826 [95% CI: 1.387-2.404]). The total complication rate was 15.4% in the DCS group and 15.8% in the LISS group (p = 0.641). The mean loss of coronal fracture fragment angle was -0.77 degrees in the DCS group and -0.19 degrees in the LISS group (p = 0.125).

CONCLUSION

Minimally invasive percutaneous plating with the DCS or the LISS provides good outcome with few complications in the treatment of distal femoral fractures. Both systems minimize soft tissue trauma. LISS seems to have lower risk of early implant loosening than the DCS.

The use of calcium sulfate and calcium phosphate composite graft to augment screw purchase in osteoporotic ankles

BACKGROUND

Screws placed in the distal fibula may not have satisfactory purchase during internal fixation of an osteoporotic ankle fracture. Tibia-pro-fibula screws that extend from the fibula into the distal tibial metaphysis provide additional purchase. The purpose of this study was to investigate if purchase of these screws can be enhanced further by injecting calcium sulfate and calcium phosphate composite graft into the drill holes prior to insertion of the screws.

MATERIALS AND METHODS

Bone density was quantified using a DEXA scan in paired cadaver legs. One leg from each pair was randomly selected for injection of composite graft into the screw holes before insertion of the screws. Two screws were inserted through the fibula into the distal tibial metaphysis in each leg, at the level of the syndesmosis under fluoroscopy in a standardized fashion in an MTS machine.

RESULTS

After testing 4 pairs of cadaver legs, a statistically significant difference was noted in displacement (p = 0.018 distal, p = 0.0093 proximal), failure load, (p = 0.0185 distal, p = 0.0238 proximal), and failure energy (p = 0.0071 distal, p = 0.0115 proximal) between augmented and non-augmented screws, with the augmented screws being considerably stronger.

CONCLUSION

Screws augmented with composite graft provide significantly greater purchase in an osteoporotic fibular fracture model.

CLINICAL RELEVANCE

Composite graft augmented screws inserted into the distal tibia from the fibula may enhance the stability of internal fixation of an osteoporotic ankle fracture. This may enable earlier weightbearing and return to function which is important in elderly patients.

Biomechanical considerations in plate osteosynthesis: the effect of plate-to-bone compression with and without angular screw stability

OBJECTIVE

We compared the biomechanical stability of bone-plate constructs using a compression plate (CP), an internal fixator (IF), and a combination plate (CP/IF).

METHODS

Standardized simulated shaft fractures with a segmental defect in composite bones (n=60) and intraarticular distal femur fractures with a comminuted supracondylar zone in fresh frozen cadaveric femurs (n=36) were stabilized by CP, IF, and CP/IF. Construct stiffness, plastic deformation, and fixation strength were measured under axial compression and torsion using a biaxial testing machine.

RESULTS

The experimental results indicate for the distal femur fracture model that IF has less loss of reduction by plastic deformation under axial load compared to CP (IF 61% of CP). Under torsion, the CP showed significantly (P<0.05) decreased plastic deformation compared to the IF (CP 51% of IF). The combination (CP/IF) of the 2 fixation principles generally resulted in a higher load to failure under axial compression and torsion (145% failure load of CP and 118% of IF under axial compression, 88% of CP and 109% of IF under torsion). Results were similar between the 2 fracture models.

CONCLUSIONS

Under compression, IF provides similar fixation in comminuted fractures and was better than the CP for avoiding loss of reduction, whereas under torsional loading, CP was more important for stiffness, plastic deformation, and load to failure than IF. However, combination (CP/IF) fixation seems advisable in intraarticular and extraarticular fractures of long bones with a metaphyseal comminution. These data may be utilized by surgeons to build a more specific treatment plan in patients with these fracture types.

Mechanical evaluation of fracture fixation augmented with tricalcium phosphate bone cement in a porous osteoporotic cancellous bone model

OBJECTIVE

The purpose of this study was to examine the effects of resorbable bone cement on screw and plate-screw fracture fixation in a porous osteoporotic bone model.

METHODS

Experiment 1: Screw pullout strength was assessed for 4 sets of 4.5-mm cortical screws inserted into a synthetic osteoporotic cancellous bone model, including screws inserted without cement augmentation (control), screws augmented with tricalcium phosphate (TCP) bone cement (Norian SRS; Synthes USA, Paoli, PA), and screws augmented with polymethylmethacrylate. Experiment 2: The effects of cement augmentation on plate-screw fixation strength were examined by performing cantilever bending tests on 4 sets of 8 plate-screw constructions, including nonaugmented and TCP-augmented standard and locked screw-plate constructions in a similar bone model.

RESULTS

Experiment 1: Cement augmentation with both TCP and polymethylmethacrylate increased screw pullout strength from a porous osteoporotic cancellous bone model by about 4-fold (P < 0.05), and there was no significant difference between the 2 cements (P > 0.1). Experiment 2: Fixation strength was 1.5 times higher for locked plates compared with standard plates when neither was augmented with cement (P = 0.07). Cement augmentation with TCP improved fixation strength by 3.6 times for a standard plate-screw construction (P < 0.05) and 3.3 times for a locked plate-screw construction (P < 0.05). The most stable construction was the TCP-augmented locked plate, in which a 5-fold increase was observed compared with that of standard plates without TCP (P < 0.05).

CONCLUSIONS

This study indicates augmenting screws with TCP cement during osteosynthesis improves fixation strength in an osteoporotic cancellous bone model.

CLINICAL RELEVANCE

: In fracture situations in which osteoporotic bone makes screw and screw-plate fixation tenuous, screw augmentation with TCP cement should be considered as adjunct treatment.

Principles of fixation of osteoporotic fractures

Despite advances in the prevention and treatment of osteoporotic fractures, their prevalence continues to increase. Their operative treatment remains a challenge for the surgeon, often with unpredictable outcomes. This review highlights the current aspects of management of these fractures and focuses on advances in implant design and surgical technique.

Distal femoral fractures treated by hinged total knee replacement in elderly patients

Although the use of constrained cemented arthroplasty to treat distal femoral fractures in elderly patients has some practical advantages over the use of techniques of fixation, concerns as to a high rate of loosening after implantation of these prostheses has raised doubts about their use. We evaluated the results of hinged total knee replacement in the treatment of 54 fractures in 52 patients with a mean age of 82 years (55 to 98), who were socially dependent and poorly mobile.

Within the first year after implantation 22 of the 54 patients had died, six had undergone a further operation and two required a revision of the prosthesis. The subsequent rate of further surgery and revision was low.

A constrained knee prosthesis offers a useful alternative treatment to internal fixation in selected elderly patients with these fractures, and has a high probability of surviving as long as the patient into whom it has been implanted.

Operative treatment of acute distal femur fractures: systematic review of 2 comparative studies and 45 case series (1989 to 2005)

BACKGROUND

The incidence of distal femur fractures is approximately 37 per 100,000 person-years. Typically, distal femur fractures are caused by a high-energy injury mechanism in young men or a low-energy mechanism in elderly women. Managing these fractures can be a challenging task. Most surgeons agree that distal femur fractures need to be treated operatively to achieve optimal patient outcomes. The articular fracture component is usually treated with open reduction and internal lag screw fixation or external tension wire fixation (Illizarov). However, there is no consensus on the type of implant for the fixation of the metaphyseal-diaphyseal fracture component.

OBJECTIVE

The aim of this study is to systematically summarize and compare the results of different fixation techniques (traditional compression plating, antegrade nailing, retrograde nailing, submuscular locked internal fixation, and external fixation) in the operative management of acute nonperiprosthetic distal femur fractures (AO/OTA type 33A and C) and the characteristics of the fractures for each treatment (articular/nonarticular and open/closed). Additionally an attempt was made to evaluate the impact of surgical experience on nonunion rate, fixation failure rate, deep infection rate, and secondary surgical procedure rate. In the context of this article compression plating relates to techniques/implants that require compression of the implant to the femoral shaft-it does not relate to interfragmentary compression.

Biomechanical evaluation of the less invasive stabilization system, angled blade plate, and retrograde intramedullary nail for the internal fixation of distal femur fractures

OBJECTIVE

To evaluate the stability of the retrograde intramedullary nail (IMN), angled blade plate (ABP), and a locked internal fixator (Less Invasive Stabilization System [LISS], Synthes, Paoli, PA) for internal fixation of distal femur fractures.

DESIGN

Destructive biomechanical testing of matched pairs of fresh-frozen human cadaveric bone-implant constructs.

SETTING

Biomechanical laboratory.

METHODS

A fracture model was created to simulate an AO/OTA33-A3 fracture. Forty-eight matched pairs of specimens were used. Six groups of 8 pairs each were tested to failure: LISS versus ABP and LISS versus IMN (axial, torsional, and cyclical axial).

MAIN OUTCOME MEASUREMENT

Load to failure, mode of failure, energy to failure, displacement at the load to failure, and stiffness.

RESULTS

Fixation strength (load/moment to failure) of the LISS constructs was 34% greater in axial loading (P = 0.01) and 32% less in torsional loading (P = 0.05) compared with ABP constructs and 13% greater in axial loading (P = 0.35) and 45% less in torsional loading (P < 0.01) compared with IMN constructs. Loss of distal fixation in axial loading occurred in 1 of 16 cases with the LISS, in 3 of 8 cases with the ABP, and in 8 of 8 cases with the IMN. Cyclical axial loading demonstrated significantly less plastic deformation for the LISS construct compared with ABP constructs (P < 0.01) and similar plastic deformation compared with IMN constructs (P = 0.98).

CONCLUSIONS

All 3 fixation devices (LISS, ABP, and IMN) offer sufficient torsional stability and sufficient proximal fixation that withstands axial loading without failing. The LISS provides improved distal fixation, especially in osteoporotic bone, at the expense of more displacement at the fracture site.

Treatment of distal femur fractures using the less invasive stabilization system: surgical experience and early clinical results in 103 fractures

OBJECTIVE

To summarize the complications and early clinical results of 123 distal femur fractures treated with the Less Invasive Stabilization System (LISS; Synthes, Paoli, PA).

DESIGN

Retrospective analysis of prospectively enrolled patients.

SETTING

Two academic level I trauma centers.

SUBJECTS AND PARTICIPANTS

One hundred nineteen consecutive patients with 123 distal femur fractures (OTA type 33 and distal type 32 fractures) treated by 3 surgeons. One hundred three fractures (68 closed fractures and 35 open fractures) in 99 patients were followed up at least until union (mean follow-up = 14 months, range: 3-50 months).

INTERVENTION

Surgical reduction and fixation of distal femur fractures.

MAIN OUTCOME MEASUREMENTS

Perioperative complications, radiographic union, infection rate, loss of fixation, alignment, and range of motion.

RESULTS

Ninety-six (93%) of 103 fractures healed without bone grafting. All fractures eventually healed with secondary procedures, including bone grafting (1 of 68 closed fractures and 6 of 35 open fractures). There were 5 losses of proximal fixation, 2 nonunions, and 3 acute infections. No cases of varus collapse or screw loosening in the distal femoral fragment were observed. Malreductions of the femoral fracture were seen in 6 fractures (6%). The mean range of knee motion was 1 degrees to 109 degrees .

CONCLUSIONS

Treatment of distal femur fractures with the LISS is associated with high union rates without autogenous bone grafting (93%), a low incidence of infection (3%), and maintenance of distal femoral fixation (100%). No loss of fixation in the distal femoral condyles was observed despite the treatment of 30 patients older than 65 years. The LISS is an acceptable surgical option for treatment of distal femoral fractures.

Primary total knee arthroplasty for complex distal femur fractures in elderly patients

Fractures of the distal femur in the geriatric population are associated with a high incidence of postoperative complications and poor results. Nonunion, loss of fixation, and malunion of these fractures occur with all types of treatment. The postoperative treatment of these patients demands a lengthy period of limited weightbearing that can increase the rate of medical complications. Our experience with these challenging fractures caused us to consider the use of a primary distal femur replacement total knee arthroplasty with the goals of elimination of fracture healing issues, early mobilization, and immediate weightbearing. Twenty-four distal femoral replacement knee arthroplasties were done from July 1998 to January 1999. Reviewed with a mean followup of 11 months, 17 patients (71%) resumed their preoperative level of ambulation. Knee range of motion averaged 1 degree - 103 degrees. No major surgical or significant medical complications were experienced by these patients. Our experiences with this small number of patients have shown that an immediate arthroplasty offers many advantages over open reduction and internal fixation for geriatric patients with poor bone quality, preexisting degenerative joint disease, and medical problems.

The Effect of Divergent Screw Placement on the Initial Strength of Plate-to-Bone Fixation

BACKGROUND

Numerous implants exist that allow screws to be placed at varying angles for lag fixation or to fix additional fragments. This study determined how placing screws at different angles affects fixation strength.

METHODS

Using a bone model, we first investigated the pullout strength of screws inserted at varying angles; then, we studied the strength of plate-bone constructs with end screws placed at divergent angles.

RESULTS

Varying the screw angle from 0 to 10 to 20 degrees progressively weakened the screw pullout resistance. No additional decrease was found in varying the angle further. In contrast, the strength of fixation of plate to bone was higher for constructs with screws placed at 20 or 30 degrees off of perpendicular when tested in gap-open bending and axial compression (all p < 0.05). No such differences were found in torsion.

CONCLUSION

The pullout strength with angled screws is reduced, but this does not translate into reduced strength of the bone-to-plate interface.

Internal fracture fixation in patients with osteoporosis

Because of the decreased holding power of plate-and-screw fixation in osteoporotic bone fractures, internal fixation can have a high failure rate, ranging from 10% to 25%. Screws placed into cortical bone have better resistance to pullout than do those placed into adjacent trabecular bone. Plates should not be used to bridge unstable regions of bony comminution in osteoporotic patients. Fixation stability is optimized by securing stable bone contact across the fracture site and by placing screws both as close to and as far from the fracture as possible. Intentional shortening can improve stability and load sharing of the fracture construct. Structural bone graft or other types of fillers can be used to fill voids when comminution prevents stable contact. Load-sharing fixation devices such as the sliding hip screw, intramedullary nail, antiglide plate, and tension band constructs are better alternatives for osteoporotic metaphyseal locations. Proper planning is essential for improved fracture fixation in this high-risk patient group.

A new method of fixation in osteoporotic bone. A preliminary report

Over-tightening of cortical bone screws in osteoporotic bone results in weak fixation. Once a screw is over-tightened and the bone thread form is stripped, there are limited means at the surgeon's disposal to rescue the situation, none of them entirely satisfactory. We describe a simple device that is specifically designed to resolve this problem. It consists of a nylon cavity plug and applicator. The plug is inserted into the stripped hole and the screw re-applied and tightened in the normal manner. The plug expands and forms a load-bearing region on the inner face of the bone. Tests on osteoporotic cadavaric bone have shown that the plug effectively re-establishes screw fixation. When compared to an over-tightened screw, the plug is at least twice as resistant to loads acting to pull the screw out of the surrounding bone.

Augmentation of cancellous screw fixation with hydroxyapatite composite resin (CAP) in vivo

The fixation of fractured bone with screws is important for orthopedic surgery, however, rigid fixation often cannot be attained in elderly patients with osteoporosis. Recently, we developed a new injectable, nonresorbable bone cement (CAP) that possesses mechanical and biological properties superior to those of polymethylmethacrylate (PMMA) cement. CAP can directly bond with bone without intervening fibrous tissue, and the peak curing temperature is 46 degrees C. In this study, we assessed the effects of CAP and PMMA cement on the augmentation of screw fixation in vivo. A cancellous screw was placed in the proximal metaphysis of rabbit tibiae. One side of each tibia was randomly selected to be augmented with CAP or PMMA. The contralateral side received a screw without cement (control). Of the 36 rabbits included in this study, 9 rabbits from each group were sacrificed and the tibial constructs retrieved 1 or 3 months after the initial operation. The screws were then pulled out to failure. The values of the pullout force of the screws augmented with CAP and PMMA were higher than those of the control specimens at both 1 month (319 +/- 58 N for CAP vs. 105 +/- 41 N for control; p < 0.05, 284 +/- 100 N for PMMA vs. 132 +/- 71 N for control; p < 0.05) and 3 months (387 +/- 109 N for CAP vs. 196 +/- 107 N for control; p < 0.05, 372 +/- 145 N for PMMA vs. 242 +/- 100 N for control; p > 0.05) after the operation. However, the average increase in the pullout force between CAP and PMMA augmentation was not statistically significant at either time. The values of energy absorption augmented with CAP and PMMA were also higher than those of the control specimens at both 1 month (129 +/- 54 N*mm for CAP vs. 19 +/- 10 N*mm for control; p < 0.05, 145 +/- 95 N*mm for PMMA vs. 28 +/- 21 N*mm for control; p < 0.05) and 3 months (172 +/- 58 N*mm for CAP vs. 44 +/- 41N*mm for control; p < 0.05, 185 +/- 198 N*mm for PMMA vs. 67 +/- 49N*mm for control; p > 0.05) after the operation. However, there were also no significant differences in energy absorption between the two types of cement augmentation. On the other hand, a significant increase was not observed in stiffness among the CAP, PMMA, and respective control groups at either 1 month (626 +/- 133 N/mm for CAP vs. 441 +/- 180 N/mm for control; p < 0.05, 577 +/- 87 N/mm for PMMA vs. 450 +/- 121 N/mm for control; p > 0.05) or 3 months (622 +/- 144 N/mm for CAP vs. 600 +/- 204 N/mm for control; p > 0.05, 633 +/- 175 N/mm for PMMA vs. 630 +/- 168 N/mm for control; p > 0.05) after the operation, except in the average increase between CAP augmentation and its control 1 month after the operation. These results suggested that a cancellous screw fixation augmented with CAP, as well as PMMA, was effective compared with the unaugmented control in vivo. Because of its biocompatibility and low curing temperature, CAP can be used clinically to augment cancellous screw fixation.

Mechanical comparison of endosteal substitution and lateral plate fixation in supracondylar fractures of the femur

OBJECTIVE

To assess for improved rigidity with the addition of a medial endosteal plate to laterally plated supracondylar femoral fractures.

DESIGN

A randomized paired study in a supracondylar femoral fracture model comparing two fixation methods tested cyclically in axial and torsional loading.

METHODS

One-centimeter supracondylar gap osteotomies were created in twenty synthetic femurs approximately six centimeters proximal to the knee joint. Ten were stabilized with a lateral eight-hole buttress plate alone, and ten were secured by a similar lateral buttress plate plus a medial endosteal eight-hole dynamic compression plate. Group 1 (n = 5; lateral plate alone) and Group 2 (n = 5; lateral and endosteal plates) were axially loaded up to 700 newtons through a materials test system for three cycles. A displacement transducer detected movement at the medial fracture gap. Group 3 (n = 5; lateral plate alone) and Group 4 (n = 5; lateral and endosteal plates) were tested in torsion. A rod-and-pulley system created an external rotation torque up to twenty Newton-meters for three cycles. A rotary potentiometer measured angular displacement.

RESULTS

Lateral buttress plating with endosteal substitution showed statistically significant decreased motion at the fracture site in torsional (p < 0.004) and axial loading (p < 0.0001) versus lateral buttress plating alone using Student's t test.

CONCLUSION

The addition of a 4.5-millimeter endosteal plate to a lateral buttress plate provides significantly increased stability, as compared with lateral plating alone in a femoral supracondylar fracture model during simulated axial and torsional loading. Neither fixation construct, however, restored the torsional stability of the distal femur to its preinjury (intact) level.

New technique for treatment of unstable distal femur fractures by locked double-plating: case report and biomechanical evaluation

BACKGROUND

A comminuted, intra-articular distal femur fracture was surgically treated by the authors with a locked, double-plating technique because fixation stability could not be initially achieved by using a standard double-plating technique. The purpose of this study was to determine biomechanically whether a locked double-plate construct would enhance fixation stability compared with a nonlocked double-plate construct.

METHODS

Six matched pairs of mildly osteopenic femurs were selected and all had a reproducible intra-articular fracture pattern created. Each pair underwent fixation with either a double-plating construct or a locked, double-plating construct that was randomly assigned. The instrumented femurs were then mechanically tested in several loading modes to determine fixation stability. After initial testing, specimens were cyclically loaded and retested for stability.

RESULTS

The locked, double-plating construct provided significantly greater fixation stability than the standard double-plating construct in precycling and postcycling biomechanical testing.

CONCLUSION

The technique described is particularly applicable for severely comminuted fractures of the distal femur and fractures in osteopenic bone with poor screw purchase. It offers a simple alternative for enhancing fixation stability, which avoids the potential complications of methylmethacrylate-enhanced screw fixation.

The supracondylar intramedullary nail in elderly patients with distal femoral fractures

From February 1994 until July 1997, a prospective study of all elderly patients with a displaced distal femoral fracture, who were treated with an intramedullary supracondylar nail, was made. The outcome of 31 fractures in 30 elderly patients was studied. The average age was 82 years (55-98). Two-thirds of the patients had had previous ipsilateral femoral pathology. Average acute hospital stay was 17 days. All patients were reviewed at 6 months and all cases have been followed for over 1 year. More than 90% of surviving fractures had healed within 6 months of the operation. Outcome scores were; 22 (85%) excellent or satisfactory, 2 (7.5%) unsatisfactory and 2 (7.5%) failures. The mortality rate was 17% at 6 months and 30% at 1 year, which is similar to patients with a fractured neck of femur. This nail is recommended for its versatility and favourable outcome scores in this age group.

Angulated screw placement in the lateral condylar buttress plate for supracondylar femoral fractures

Certain supracondylar femoral fractures are not amenable to internal fixation with fixed angle devices. In these instances, the condylar buttress plate is the recommended alternative; however, this is a less rigid device. Because of the decreased rigidity and strength of this device, there is a tendency toward varus angulation and malunion. In six fresh-frozen human knee specimens, segmental osteotomies were created to mimic supracondylar femoral fractures. The medial cortex was completely removed to make the fracture unstable to varus deformity. The fracture was fixed with a lateral condylar buttress plate using 4.5 mm screws. Each specimen was tested once with all the screws installed perpendicular to the plate, and again with the middle screw, just proximal to the fracture, angled 45 degrees diagonally across the fracture into the subchondral bone of the medial femoral condyle. For the construct with all screws placed perpendicular to the buttress plate, the initial stiffness was 410 N/mm, and after 1000 cycles it was 230 N/mm. With a screw placed diagonally across the fracture site, stiffness increased to 833 N/mm on the first cycle, and 796 N/mm after 1000 cycles. In all specimens with the screws placed perpendicular to the plate, the distal fragment had a permanent varus deformity after 1000 cycles, under no load, of 0.91 mm. For the diagonal screw condition, the average magnitude for all six specimens was 0.42 mm. This simple means of screw angulation in the plate strengthened the overall construct to resist the tendency toward varus deformity. The attractive features include the ease of application, and the use of an existing construct.

Comparative biomechanical analysis of supracondylar femur fracture fixation: locked intramedullary nail versus 95-degree angled plate

OBJECTIVES

To compare the initial stability of the genucephalic (GSH) intramedullary nail and the 95-degree condylar compression screw and side plate (DCS) for distal femur fractures.

DESIGN

Human cadaveric biomechanical study.

PARTICIPANTS

Twelve matched pairs of fresh frozen human cadaveric femurs.

INTERVENTION

Genucephalic intramedullary nail device (Smith and Nephew Richards, Memphis, TN, U.S.A.) and the 95-degree DCS device (Synthes USA, Paoli, PA, U.S.A.) were compared. Grouped or dispersed screw constructs were tested for each fracture fixation system with progressively more severe simulated fracture patterns.

MAIN OUTCOME MEASUREMENT

Axial and torsional stiffness values.

RESULTS

The DCS plate with the dispersed screw configuration had the greatest torsional stiffness (p < 0.0011). The GSH nail with the grouped screw configuration absorbed more energy (work) during axial loading compared with the plate constructs (p < 0.0007). There were no significant differences in axial or torsional stiffness within treatment groups for fracture patterns of increasing severity.

CONCLUSIONS

Based on the authors' results, the selection of a GSH nail or a DCS plate should not be determined by the severity of the fracture. If a DCS plate construct is selected, the authors recommend a dispersed screw configuration, including the most proximal hole in the plate, to provide superior stiffness in torsional loading and equal stiffness in axial loading when compared with the GSH nail constructs. If a GSH nail is selected, the authors recommend a grouped screw configuration, which absorbed more energy during axial loading compared with the DCS plate constructs and the nail with the dispersed screw configuration.

The results of open reduction and Internal fixation of distal femur fractures using a biologic (indirect) reduction technique

The results of 57 A-O type A or C supracondylar femur fractures treated by open reduction and internal fixation using indirect reduction techniques are reported. No bone grafting or dual plating was used. All patients were placed in a continuous passive motion (CPM) machine postoperatively. Patients were followed at 4-week intervals until fracture healing had occurred. All patients were followed for at least 1 year after injury. All fractures were treated by a single surgeon. The average time for fracture healing was 10.7 weeks (range 8-16). Hardware failure did not occur in this series. Outcomes were assessed using a modified Schatzker scoring method. Using the scale, there were 84% good to excellent results, 11% fair results, and 5% poor outcomes. Fair and poor results tended to occur in more severe fractures and were primarily due to limited knee motion. Complications included two broken screws, one deep infection, and one malunion. No fractures failed to unite. In conclusion, holding the surgical skill factor constant, it appeared that biologic reduction techniques, although they provided excellent bone healing capability, did not guarantee universally satisfactory outcomes.

Supracondylar femoral fracture following total knee arthroplasty

Twenty-nine supracondylar femoral fractures above total knee arthroplasty were studied retrospectively. Group 1 consisted of 5 nondisplaced fractures managed with closed treatment, yielding 5 satisfactory results. Group 2 consisted of 9 displaced fractures managed with closed treatment. There were no satisfactory results in Group 2; there were 8 malunions and 2 knees requiring revision. Group 3 consisted of 15 displaced fractures managed with open reduction and internal fixation. There were 10 satisfactory results in Group 3; there were 2 malunions and 3 knees requiring revision or repeat fixation. On the basis of these results, closed treatment for nondisplaced fractures is recommended. If displacement exists, early open reduction and internal fixation yields the greatest chance for a satisfactory result, though it has a significant complication rate.

The reinforcement of cancellous bone screws with calcium phosphate cement

The ability of calcium phosphate cement (CPC) to reinforce cancellous screws placed in previously stripped holes was studied in vitro. The distal end of canine femurs were harvested. A total of 15 screws were placed in six femurs. The pullout strength (failure force), failure displacement, stiffness, and energy absorbed were determined for the screws in the intact cancellous bone. Next, these stripped screw holes were packed with CPC. The pullout test was repeated, and the results were compared using a paired, Student's t test. We found that the CPC was able to reinforce the previously stripped holes and significantly increase the pullout strength (1,159 +/- 278 N versus 678 +/- 297 N) and the stiffness (1,990 +/- 569 N/mm versus 1,519 +/- 609 N/mm) of the constructs, as well as the energy absorbed by the constructs until failure (467 +/- 180 N.mm versus 278 +/- 140 N.mm). There was no difference in the failure displacement (0.94 +/- 0.23 versus 0.85 +/- 0.51 mm). This study documents the ability of CPC to acutely reinforce cancellous bone screws in a region with no or poor-quality cancellous bone.

Retrograde intramedullary nailing of supracondylar femur fractures above total knee arthroplasty. A preliminary report of four cases

Four supracondylar fractures of the femur in three patients with total knee arthroplasties were treated by retrograde intramedullary nailing using an interlocking renamed nail (GSH Nail, Smith and Nephew Richards, Memphis, TN) specifically designed for fractures of the distal femur. Three cases were acute fractures and one was a refracture through a screw hole of a previously plated supracondylar fracture. All fractures healed and there were no complications. The procedure is performed by closed nailing using fluoroscopic guidance with the nail placed through the intercondylar notch of the femoral prosthesis and interlocking to the fracture fragments with a percutaneous targeting device. The advantages are that the procedure is performed by closed techniques that preserve the fracture hematoma and reduce operative blood loss, the fracture is stabilized by a load-sharing nail, and immediate motion with limited weight bearing is possible.