Second-generation intramedullary supracondylar nail for distal femoral fractures

Evaluation of the mechanical behaviour of the expandable wedge locked nail fixation in retrograde use: A finite element study

INTRODUCTION

In literature, there have been many studies conducted to research the alternatives of standard interlocking intramedullary nailing. The expandable wedge locked nail fixation, which is thought as a new alternative to the standard interlocking nailing, has been presented in previous numerical studies. The antegrade usage of the wedge locked nail fixation has provided promising results. From this point, the aim of the study is to evaluate mechanical behavior of its retrograde usage on femur models. Additionally, another aim of the study is to investigate the effect of fracture level on mechanical properties of the fixation.

MATERIALS AND METHODS

The mechanical behaviors of the wedge locked nail and standard interlocking nail fixations were compared by finite element methods. Sawbones femurs having osteotomies at five different levels to simulate different fractures were fixed with wedge locked nail or interlocking nail by using retrograde approach. With respect to the fracture level, two different nail lengths were used. Axial compression load was applied to fixations. The mechanical behaviors of the fixations were evaluated with respect to stiffness of the fixations and stresses occurred on both implants and bones.

RESULTS

Any of the wedge locked nail fixation did not slip at canal. The stress and stiffness results were mostly close with each other for both nail types. The maximum stresses at locking elements or bones contacting these elements increased with decreased distance between the fracture and relevant locking elements.

DISCUSSION

The wedge locked nail fixation showed comparable results to the standard interlocking nail fixation with respect to the stiffness and stress. Under axial loading, wedge locked nail provided a secured fixation without any slippage and preserved its position inside the medullary canal. It may be thought as a safe alternative to the standard interlocking nail fixation for retrograde usage. Additionally, according to stress results, it is advised to the surgeons to avoid a close locking to the fracture line.

Numerical evaluation of the mechanical properties of a novel expandable intramedullary nailing: A new alternative to standard interlocking nailing

INTRODUCTION

There has been a great effort in preventing the disadvantages of distal locking in intramedullary nailing to date. From this scope, a novel expandable nail fixation eliminating distal locking screws has been designed. The primary aim of this numerical parametric study is to investigate mechanical behavior of expandable nail fixation on the fractured femur model under different contact parameters which are effective in maintaining the nail position and to specify the appropriate values of these contact parameters for a safe fixation. The second aim is to compare mechanical behavior of the expandable nail fixation with the standard interlocking nail fixation.

MATERIALS AND METHODS

The expandable nail has three wedges which are responsible for distal fixation by compressing the medullary canal in the radial direction. 4th generation Sawbones femur model was used as bone model. A transverse osteotomy with 20 mm gap was created to simulate a subtrochanteric fracture. The fixations have been examined under axial compression with 1200 N and torsion with 7 Nm. In the parametric study, the tightening torque and static friction coefficient in wedge-canal contact were selected as contact parameters. The outputs were stiffnesses of the fixations, equivalent von-Mises stress distribution on the models, and load sharing between the canal and distal locking elements.

RESULTS

The results of the parametric study showed that the model with the tightening torque of 3 Nm and friction coefficient of 0.7 was the safest. The load borne by wedges is generally prone to increase with increased tightening torque and friction coefficient. The both fixations showed close stiffness and stress values.

CONCLUSION

The tightening torque of the wedge locking mechanism is directly effective in maintaining the nail position constant in canal, and the safety of the fixation is better ensured with increased tightening torque but stress states on bone must be carefully evaluated. The expandable nail provided comparable results to standard interlocking nails with respect to the fixation stiffness, stress, and contact forces. The expandable nailing may be evaluated as an alternative in the fractures of long bones in the case that the numerical results are supported by future experimental studies.

Comparative analysis of the biomechanical behavior of anterograde/retrograde nailing in supracondylar femoral fractures

Supracondylar femoral fractures account for a noticeable percentage of the femoral shaft fractures, affecting two etiological groups: high energy trauma in young men, with good bone quality, and older women with osteoporotic femur. Surgical treatment of those kind of fractures remains controversial, with different surgical options such as plate and sliding barrel locking condylar plate, less invasive stabilization system (LISS) or intramedullary nailing, which has emerged as a new fixation choice in the treatment of that type of fractures. The present work performs a comparative study about the biomechanical behavior of anterograde and retrograde nailing in supracondylar femoral fractures type A, in order to determine the best choice of nailing and locking configuration. A three-dimensional finite element model of the femur was developed, modeling femoral supracondylar fracture and different nailing configurations, both for anterograde and retrograde nails. The study was focused on the immediately post-operative stage, verifying the appropriate stability of the osteosynthesis. The obtained results show a better biomechanical behavior for anterograde nails, providing a better stability from the point of view of global movements, lower stresses in screws, and less stress concentration in cortical bone. So, for the analyzed fractures and osteosyntheses types, anterograde nailing has demonstrated to be a better surgical option, being an excellent indication in supracondylar fractures of femur, with clear benefits compared to retrograde nailing, providing a better stabilization which enables for a more satisfactory fracture healing.

Locking plate fixation versus antegrade intramedullary nailing for the treatment of extra-articular distal femoral fractures

INTRODUCTION

The current study aimed to retrospectively analyze locked plating (LP) and antegrade intramedullary nailing (AIN) for the treatment of extra-articular distal femoral fractures.

PATIENTS AND METHODS

Between January 2000 and March 2015, 97 patients (49 male, 48 female) underwent surgery for extra-articular distal femoral fractures in our clinic. Patients were grouped based on their method of treatment (69 (71.1%) with locked plate (LP group) and 28 (28.9%) with antegrade intramedullary nailing (AIN group)), and the groups were analyzed with regards to fracture types, associated trauma, hospital stay, Injury Severity Score (ISS), nonunion, reoperation rate and Lysholm Functional Knee Score.

RESULTS

The LP and AIN groups had no significant differences with regards to age and gender. Sixteen patients (16.4%) experienced nonunion; all of these (5 (5.1%) in the AIN group and 11 (11.3%) in the LP group) required a secondary procedure (p = 0.773). ISS was significantly higher in the AIN group (p = 0.033). There were no significant differences between the two groups with regards to hardware failure, postoperative malreduction, reoperation rate, deep infection, and nonunion. However, the AIN group (mean 88) had a significantly higher Lysholm Functional Knee Score than the LP group (mean 75.9) (p = 0.019).

CONCLUSION

In our study we encountered less nonunion in AIN group. Both fixation methods offer good results; however, functional outcomes in the AIN group were significantly better than those in the LP group.

Single-Incision Double-Plating Approach in the Management of Isolated, Closed Osteoporotic Distal Femoral Fractures

INTRODUCTION

Distal femoral fractures in elderly population had recorded an increase in incidence in the last 2 decades. Lateral distal femoral locking plating is considered one of the best options especially when dealing with comminuted fractures but varus collapse of the medial femoral condyle occurs frequently in patients with osteoporosis. Anatomical reduction of the fracture with stable rigid fixation using double-plating approach allows early mobilization of geriatric population and prevents varus collapse minimizing the comorbidities in such fractures.

PATIENTS AND METHODS

Between September 2014 and January 2017, a prospective study on 23 patients with comminuted osteoporotic distal femoral fractures managed through the double-plating approach through a single parapatellar approach has been conducted. Only osteoporotic geriatric patients with isolated distal femoral fractures were included. Polytraumatized, open fractures, and fracture type 33-A1, 33-A2, and 33-B were excluded. The mean age was 69.6 years (61-80). All patients have been evaluated as regard duration of procedure, time to union, EQ-5D-5L score, the need of autologous bone grafts, range of knee motion, and presence of complications.

RESULTS

The average follow-up was 14.1 months. The majority of fractures were type 33-C2 (13 patients). Average procedure time was 148 minutes (117-193 minutes). Mean EQ-5D-5 L score was 83.8 (72-82). Average time to union was 9 months (3-12 months). Four (17.4%) cases needed autologous bone graft after 6 months. No loss of reduction in any of the cases was evident, although 6 (26%) cases had screw breakage or cutout in one of the plate fixation. Two (8.7%) patient developed superficial wound infection and 1 (4.3%) developed DVT.

DISCUSSION

This study aimed at evaluation of the success of double plating of distal femoral fractures in geriatric population. different fixation methods were studied for reduction and fixation of such a fracture such as external fixation, intramedullary nails and lateral plating. the quality of fracture reduction, functional and radiological outcomes, time to union, the need for bone grafting and complication are the main debatable issues.

CONCLUSION

Single-incision double-plating approach for distal femoral osteoporotic fractures is effective and provides stable construct without reduction loss allowing early rehabilitation. Delayed union and the need for bone graft are the major drawbacks for this technique.

Retrograde dynamic locked intramedullary nailing for aseptic supracondylar femoral nonunion after dynamic condylar screw treatment

OBJECTIVE

Supracondylar femoral nonunions after dynamic condylar screw (DCS) treatment are uncommon, and few studies have addressed an optimal treatment technique for this disorder. Re-insertion of a new plate may not be secure because of bony defects in the distal fragment, created by the lag screw of the DCS.

MATERIALS AND METHODS

Forty-two consecutive adult patients with 42 supracondylar femoral nonunions were treated with removal of the DCS, re-alignment of the knee axis, and insertion of a retrograde dynamic traditional femoral locked nail. When necessary, a humeral plate was augmented to reinforce rotational stability.

RESULTS

A final group of 36 patients with 36 nonunions were followed for an average of 2.8 years (range 1.1-6.2 years). All nonunions healed with a union rate of 100 %, and the average time to union was 4.2 months (range 2.5-5.5 months). Complications included two malunions. There were no instances of nonunion or deep infection. Satisfactory knee function among 36 patients improved from 8.2 % preoperatively to 86.1 % at the last follow-up (p < 0.001). All 36 patients could walk without aids.

CONCLUSION

The described technique may be an excellent alternative treatment for an aseptic supracondylar femoral nonunion after DCS treatment. The technique is not difficult, and the union rate and satisfactory rate are high.

Biomechanical performance of retrograde nail for supracondylar fractures stabilization

The study compared the biomechanical performance of retrograde nail used to stabilize supracondylar fracture (three different levels) by means of finite element analysis. Three different nail lengths (200, 260, and 300 mm) of stainless steel and titanium nails were under consideration. Intact femur model was reconstructed from Digital Imaging and Communications in Medicine images of Thai cadaveric femur scanned by computed tomography spiral scanner, whereas geometry of retrograde nail was reconstructed with the data obtained from three-dimensional laser scanner. The retrograde nail was virtually attached to the femur before nodes and elements were generated for finite element model. The finite element models were analyzed in two stages, the early stage of fracture healing and the stage after fracture healing. The finding indicated that purchasing proximal locking screw in the bowing region of the femur may be at risk due to the high stresses at the implant and bone. There were no differences in stress level, elastic strain at a fracture gap, and bone stress between stainless steel and titanium implant. Since the intramedullary canal requires reaming to accommodate the retrograde nail, the length of retrograde nail should be as long as necessary. However, in case that the retrograde nail can be accommodated into the intramedullary canal without reaming, the longer retrograde nail can be used.

Causative factors of fracture nonunion: the proportions of mechanical, biological, patient-dependent, and patient-independent factors

BACKGROUND

Understanding the causative factors of fracture nonunion leads to both prevention and improvements in treatment. The purpose of this study was to understand the clinical characteristics and causative factors of nonunion in a case series.

METHODS

One hundred two consecutive patients with fracture nonunions of the extremities who were surgically treated in our hospital over the last decade were analyzed. Data were collected by reviewing medical charts. Radiographs were reviewed to classify the nonunion by radiographic appearance. Causative factors of nonunions were identified for each patient. Factors relating to inadequate mechanical stability or reduction and those relating to a decline in biological activity were investigated. Mechanical factors included inappropriate dynamization, inappropriate reduction, inappropriate surgical management, insufficient fixation, and conservative treatment. Surgical technical errors were identified through careful review by three experienced trauma surgeons. Biological activity factors included comminution and bone loss, open fracture, excessive surgical exposure, infection, previous radiation therapy, alcohol abuse, diabetes mellitus, smoking, genetic disorders, and metabolic disease or endocrine pathology. We also classified the causative factors as patient-dependent or patient-independent factors.

RESULTS

Of the 102 nonunions, 47 were oligotrophic, 22 were hypertrophic, 17 were atrophic, 12 were defect types, and 4 were comminuted. Twenty-four cases had factors of inadequate mechanical stability or reduction, 23 cases had biological factors, and 55 cases had both types of factors. Four cases had patient-dependent factors, 40 cases had patient-independent factors, and 58 cases had both types of factors.

CONCLUSIONS

Our results demonstrated that there were a considerable number of nonunions with causative factors which can be improved, such as inadequate fracture management.

Infra-isthmal fracture is a risk factor for nonunion after femoral nailing: a case-control study

BACKGROUND

The rates of nonunion after femoral nailing are currently reported to be 4.1-12.5 %. The purpose of this study was to identify the risk factors of noninfected nonunion after femoral nailing, focusing in particular on the effects of the length of the distal main fragment.

METHODS

A case-control study was conducted with 105 patients, with a case (nonunion group)-control (control group) ratio of 1:2. The nonunion group (n = 35) comprised patients with consecutive symptomatic nonunions after femoral nailing who were treated in our institute; the control group (n = 70) were matched by age to the nonunion group. Type of fracture, soft tissue injury, length of femur and nail length, incidence of screw breakage, nail diameter, mean length of distal main fragment, and any episode of dynamization were retrospectively examined. Univariate and multivariate analyses were performed to elucidate the risk factors of nonunion after femoral nailing.

RESULTS

Increased risk of nonunion after femoral nailing was associated with (1) open fracture, (2) screw breakage, (3) shorter length of a distal fragment, and (4) any episodes of dynamization. Receiver operating characteristic analysis showed that a distal fragment length of <43 % of the total femur length was the cutoff level for nonunion after nailing. The odds ratio for nonunion was 6.40 (95 % CI 2.70-15.2) when the length of the distal main fragment was <43 % of the femur length. Multivariate logistic analysis revealed that the risk of nonunion after femoral nailing increased (1) with breakage of locking screws (p = 0.0021), (2) with dynamization (p = 0.0029), (3) with a shorter distal fragment length (p = 0.0379), and (4) with an open fracture (p = 0.0397).

CONCLUSION

The elucidated risk factors of nonunion after femoral nailing were identified as open fracture, infra-isthmal femoral fracture, breakage of locking screw, and inappropriate dynamization. We believe that the surgeon should be consciously aware of the need for additional surgical fixation for the distal fragment when performing femoral nailing of infra-isthmal femoral fractures.

Distal femoral fixation: a biomechanical comparison of retrograde nail, retrograde intramedullary nail, and prototype locking retrograde nail

BACKGROUND

Distal femur fractures continue to be a complex surgical problem for which the incidence is increasing. Presently, there is a need for different constructs to address these complex fractures. This study attempts to define the biomechanical properties of several implants.

METHODS

A novel, prototype locking retrograde intramedullary nail and the Russell-Taylor femoral retrograde nail were tested at non-destructive, physiological, axial mode load strength using a young, synthetic bone model for a medial segmental shaft defect in the supracondylar region of the distal femur (medial gap of 10mm, 65mm proximal to the distal joint and parallel to the knee axis). Each specimen was compressively loaded and unloaded to the peak load for 80,000cycles at a 0.5Hz frequency. These were compared to the results from the same lab of the retrograde Trigen intramedullary nail. Motion and peak displacement were measured across the fracture site as a reflection of construct stability.

FINDINGS

Previous testing demonstrated that Trigen intramedullary nail had significantly less motion across the gap and increased overall stiffness of the construct (P<0.05) compared to both Russell-Taylor and prototype nails.

INTERPRETATION

Locking technology used in a nail biomechanically appears to lead to more micro-motion across the fracture gap and to less stiffness in this construct. Further research needs to be invested into intramedullary, locking technology before introducing it into clinical practice.

Treatment of acute distal femur fractures

An emphasis on indirect reduction techniques to restore limb alignment has improved the rate of fracture healing and decreased infection rates, fixation failure, and the need for bone grafting.

Retrograde femoral nailing in elderly patients with supracondylar fracture femur; is it the answer for a clinical problem?

BACKGROUND

Supracondylar fractures of femur constitute 7% of all femoral fractures. In elderly patients, they are invariably low-energy fractures predisposed to by osteoporosis. Treatment of these fractures in the elderly is a challenging task for most orthopaedic surgeons. There is no consensus on what would be the ideal treatment for such cases. This study looks at the results of retrograde femoral nailing as a treatment option for this vulnerable group of patients.

PATIENTS AND METHODS

This retrospective study looks at 23 elderly patients with supracondylar fractures of the femur treated by retrograde femoral nailing. Patients had an average age of 75 years (range between 65 years and 97 years). All patients were assessed with regard to operative time, blood loss, hospital stay, and postoperative complications. All patients were assessed clinically and radiologically every 6 weeks for average period of 14 months (range 12 to 18 months).

RESULTS

two patients died a few weeks postoperatively. Average operative time 70 minutes, average blood loss 350ml. Radiologically all cases united, 39.2% had angular malalignment. There were no cases of implant or fixation failure.

CONCLUSION

Retrograde femoral nailing is a surgically limited and reliable procedure for elderly patients with supracondylar fractures of the femur without intra-articular extension. Although it has a high incidence of angular malalignment, the overall functional demands of this age group are perhaps not affected much by that particular complication.

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.

Distal femoral fractures: a review of fixation methods

The treatment of distal femoral fractures has evolved; nevertheless, these fractures remain difficult to treat and carry an unpredictable prognosis. Over the years, many different strategies have been used with varying success. This review outlines the problems presented by distal femoral fractures and the results of current surgical techniques.

The role and efficacy of retrograding nailing for the treatment of diaphyseal and distal femoral fractures: a systematic review of the literature

The aim of this analysis has been to evaluate the efficacy of retrograde nailing in the treatment of distal femur and femoral shaft fractures. Articles were extracted from the Pubmed database and the retrieved reports were included in the study only if pre-specified eligibility criteria were fulfilled. Moreover, a constructed questionnaire was administered, aimed at assessing the quality of the outcomes. Twenty-four articles were eligible for the final analysis, reviewing a total of 914 patients (mean age of 48.8 years) who sustained 963 distal and diaphyseal femoral fractures. The overall mortality rate was 5.3%. The incidence of infection was 1.1% and for septic arthritis of the knee was 0.18%. In patients with distal femoral fractures, the mean time to union and rate to union were 3.4 months and 96.9%, respectively. The mean range of knee motion was 104.6 degrees . The rates of knee pain, malunion and re-operations were 16.5, 5.2 and 17%, respectively. Patients with femoral shaft fractures had a mean time to union 3.2 months, whilst the rate of union was 94.2%. The mean range of knee motion was 127.6 degrees . The rates of knee pain, malunion and re-operations were 24.5, 7.4 and 17.7%, respectively. We concluded that retrograde intramedullary nailing appears to be a reliable treatment option, mainly for distal femoral fractures. However, in the management of diaphyseal fractures, retrograde intramedullary nailing is associated with high rates of knee pain and lower rates of fracture union.

Supracondylar femoral fractures in elderly patients treated with the dynamic condylar screw and the retrograde intramedullary nail: a comparative study of the two methods

INTRODUCTION

The objective of this study is to present the results of surgical management of supracondylar fractures of the femur (types A and C according to the AO/ASIF classification) in elderly patients with the use of two different methods of fixation: the mini open dynamic condylar screw fixation (DCS) and the closed retrograde intramedullary nailing (RIN).

MATERIALS AND METHODS

Eighty patients with supracondylar fractures of the femur were treated from January 1994 to June 2000 and 72 of them followed up completely. There were 25 (34%) men and 47 (65%) women with a median age of 73.2 years (range 60-88 years). In patients with the same type of fracture, the chosen method was random, one after the other (alternately). RIN was used in 35 patients, and DCS was used in 37. The mean operative time for the DCS fixation group was 145 min (range 115-180 min), whereas for the RIN group it was 92 min (range 76-110 min) (p<0.001) with an average estimated blood loss of 310 cc (range 120-450 cc) and 118 cc (range 90-165 cc), respectively (p<0.001). The mean follow-up was 28 months (range 18-42 months).

RESULTS

According to the criteria set by Schatzker and Lambert, excellent results were recorded in 18 (51%), good in 11 (31%), moderate in 3 (9%), poor in 3 (9%) patients with RIN and excellent in 19 (51%), good in 11 (30%), moderate in 4 (11%) and poor in 3 (8%) patients with DCS (p>0.05). The complications that occurred in the RIN group were 2 (6%) stiffness of the knee (mean flexion 80 degrees), 2 (6%) non-unions, 2 (6%) varus deformity and in the DCS group 2 (5%) haematomas, 4 (11%) stiffness of the knee (mean flexion 73 degrees) and 2 (5%) non-unions.

CONCLUSION

Although the two methods appear to have the same percentage of excellent results and same time to bony union, RIN is preferable to DCS in terms of less blood loss and shorter operating time.