Retrograde intramedullary nailing of supracondylar femoral fractures: design and development of a new implant

Distal femur fractures management and evolution in the last century

PURPOSE

The purpose of this historical review is to illustrate the progression and evolution of treatment for distal femur fractures.

METHODS

Scientific literature was searched for descriptions of treatment for distal femur fractures to provide an in-depth overview of the topic, with emphasis on the evolution of surgical constructs used to treat these fractures.

RESULTS

Prior to the 1950s, distal femur fractures were treated nonoperatively, resulting in considerable morbidity, limb deformity, and limited function. As principles of surgical intervention for fractures emerged in the 1950s, surgeons developed conventional straight plates to better stabilize distal femur fractures. Angle blade plates and dynamic condylar screws emerged out of this scaffolding to prevent post-treatment varus collapse. Meanwhile, intramedullary nails, and later, in the 1990s, locking screws, were introduced to minimize soft tissue disruption. Treatment failure led to the development of locking compression plates with the advantage of accommodating either locking or nonlocking screws. Despite this advancement, the rare but significant incidence of nonunion has not been eliminated, leading to the recognition of the biomechanical environment as important for prevention and the development of active plating techniques.

CONCLUSION

Emphasis for the surgical treatment of distal femur fractures has incrementally progressed over time, with initial focus on complete stabilization of the fracture while the biological environment surrounding the fracture was ignored. Techniques slowly evolved to minimize soft tissue disruption, allow more ease of implant placement at the fracture site, and attend to the systemic health of the patient, while simultaneously ensuring appropriate fracture fixation. Through this dynamic process, the desired results of complete fracture healing and maximization of functional outcomes have emerged.

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.

Radiographic predictors of symptomatic screw removal after retrograde femoral nail insertion

INTRODUCTION

Removal of symptomatic implants is a common procedure performed by orthopaedic trauma surgeons. No guidance is available regarding which factors contribute to the likelihood of an implant becoming symptomatic. Our objective was to determine whether radiographic parameters associated with distal interlocks in retrograde femoral nails are associated with the rate of symptomatic screw removal.

PATIENTS AND METHODS

We conducted a retrospective review at a Level I trauma center. Study patients (n=442) had femoral fractures treated with retrograde intramedullary nails from 2007 to 2014 and at least 1year of follow-up. The main outcome measurement was symptomatic distal screw removal as predicted by radiographic parameters.

RESULTS

Symptomatic screw removal occurred in 12% of the patients. Increased distance between the most distal screw and the articular surface of the femur significantly reduced likelihood of symptomatic screw removal. A cutoff of 40mm from the articular block was predictive of removal (≥40mm, 0% removal; <40mm, 18% removal, p<0.0001). In patients with distal screws placed within 40mm of the articular surface of the femur, a ratio of screw length to distance between medial and lateral femoral cortices that was ≥1 was a strong predictor of symptomatic screw removal (area under Receiver Operating Characteristic curve, 0.75; p<0.0001).

CONCLUSIONS

More distal screws and screws that radiographically extend to or beyond the medial cortex are more likely to cause pain and require removal in femoral fractures treated with retrograde intramedullary nails. We identified a specific distance from the joint (<40mm) and a ratio of screw length to bone width (≥1) that significantly increased the likelihood of symptomatic screw removal. Clinicians can use these data to inform patients of the likely risk of implant removal and perhaps to better guide placement and length of screws when the clinical scenario allows some flexibility in location and length of screws.

Femoral Condyles Tangential Views: An Effective Method to Detect the Screw Penetration of Femoral Condyles After Retrograde Nailing

Background:

Postoperative knee soft tissue irritation is a common complication after retrograde nail fixation of femoral fractures. Distal locking screw prominence is one of the causes for soft tissue irritation. This study aimed to determine whether the use of the femoral condyles tangential views improve the diagnostic accuracy compared with anteroposterior (A-P) view in detecting distal locking screw penetrations during retrograde femoral nailing.

Methods:

The angle between the sagittal plane and lateral aspect of the condyle and the angle between the sagittal plane and medial aspect of condyle were measured on computed tomography (CT) images. After the angles were measured and recorded, cadaveric femurs were used in a simulated surgical procedure. The retrograde femoral nail was inserted into the femur and placed distal locking screws, which were left 2, 4, and 6 mm proud of the medial and lateral condyles for each femur. A-P view, lateral condyle tangential view and medial condyle tangential view were obtained. All fluoroscopic images were recorded and sent to three observers blinded to the experimental procedure to determine whether screws penetrated the condyle cortex or not.

Results:

According to the results of CT scan, the lateral condyle view was 20.88 ± 0.98° and the medial condyle view was 40.46 ± 3.14°. In the A-P view, we detected 0% at 2 mm penetration, 16.7% (lateral condyle screw) and 25.0% (medial condyle screw) at 4 mm, and 41.7% (lateral condyle screw) and 58.3% (medial condyle screw) at 6 mm. In the lateral tangential view, we detected 91.7% at 2 mm penetration of the lateral condyle and 100% at 4 mm and 6 mm. In the medial tangential view, we detected 66.7% at 2 mm penetration of the medial condyle and 100% at 4 mm and 6 mm. The femoral condyle tangential views provided significant improvement in detecting screw penetrations at all lengths (2, 4, and 6 mm) compared with the A-P view (P < 0.05).

Conclusions:

The femoral condyles tangential views increased the accuracy of detecting screw penetrations on the medial and lateral condyles. Routine clinical use of the femoral condyles tangential views has the potential to increase accuracy in detecting distal locking screw penetration during retrograde femoral nailing.

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.

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.

Biomechanical Characterization of an Osteoporotic Artificial Bone Model for the Distal Femur

The treatment of osteoporotic distal femur fractures is still an unsolved problem of trauma surgery. The poor bone stock often leads to secondary loss of reduction and implant failure. Therefore, the development of new implants and their biomechanical testing is essential. In a previous study, we developed and initially characterized an artificial osteoporotic bone model of the distal femur. This follow-up study was performed to characterize this model in a biomechanical comparison. We investigated two different artificial bones: five foam cortical shell (Sawbones) and 10 custom-made artificial femoral condyles. Additionally, eight human femora were used for comparison. For biomechanical testing, two intramedullary nails (distal femur nail (DFN) and supracondylar nail (SCN)) were cyclically axial loaded in an AO 33 C2 unstable distal femoral fracture model. In our testing, the artificial bone showed a decrease in the axial stiffness of 27% for the SCN and 28% for the DFN compared to the human results. Also the number of cycles for a deformation of 2.5 mm was reduced by 55% (SCN) and 62% (DFN). This decrease was homogenous and caused by the relative high bone mineral density of the human specimen used. The modes of failure showed no difference between the artificial and human bones. Our customized artificial bone provides suitable results. In relation to the human bones classified as mildly osteoporotic, we assume that the biomechanical properties match to serve as an osteoporotic bone. Yet, we suggest to check transferability of the results with human material.

Internal fixation of type-C distal femoral fractures in osteoporotic bone

BACKGROUND

Fixation of distal femoral fractures remains a challenge, especially in osteoporotic bone. This study was performed to investigate the biomechanical stability of four different fixation devices for the treatment of comminuted distal femoral fractures in osteoporotic bone.

METHODS

Four fixation devices were investigated biomechanically under torsional and axial loading. Three intramedullary nails, differing in the mechanism of distal locking (with two lateral-to-medial screws in one construct, one screw and one spiral blade in another construct, and four screws [two oblique and two lateral-to-medial with medial nuts] in the third), and one angular stable plate were used. All constructs were tested in an osteoporotic synthetic bone model of an AO/ASIF type 33-C2 fracture. Two nail constructs (the one-screw and spiral blade construct and the four-screw construct) were also compared under axial loading in eight pairs of fresh-frozen human cadaveric femora.

RESULTS

The angular stable plate constructs had significantly higher torsional stiffness than the other constructs; the intramedullary nail with four-screw distal locking achieved nearly comparable results. Furthermore, the four-screw distal locking construct had the greatest torsional strength. Axial stiffness was also the highest for the four-screw distal locking device; the lowest values were achieved with the angular stable plate. The ranking of the constructs for axial cycles to failure was the four-screw locking construct, with the highest number of cycles, followed by the angular stable plate, the spiral blade construct, and two-screw fixation. The findings in the human cadaveric bone were comparable with those in the synthetic bone model. Failure modes under cyclic axial load were comparable for the synthetic and human bone models.

CONCLUSIONS

The findings of this study support the concept that, for intramedullary nails, the kind of distal interlocking pattern affects the stabilization of distal femoral fractures. Four-screw distal locking provides the highest axial stability and nearly comparable torsional stability to that of the angular stable plate; the four-screw distal interlocking construct was found to have the best combined (torsional and axial) biomechanical stability.

Anatomical study of the placement of proximal oblique locking screws in intramedullary tibial nailing

Intramedullary tibial nailing was performed in ten paired cadavers and the insertion of a medial-to-lateral proximal oblique locking screw was simulated in each specimen. Anatomical dissection was undertaken to determine the relationship of the common peroneal nerve to the cross-screw. The common peroneal nerve was contacted directly in four tibiae and the cross-screw was a mean of 2.6 mm (1.0 to 10.7) away from the nerve in the remaining 16. Iatrogenic injury to the common peroneal nerve by medial-to-lateral proximal oblique locking screws is therefore a significant risk during tibial nailing.

Comparative endurance testing of the Biomet Matthews Nail and the dynamic compression screw, in simulated condylar and supracondylar femoral fractures

Background

The dynamic compression screw is a plate and screws implant used to treat fractures of the distal femur. The Biomet Matthews Nail is a new retrograde intramedullary nail designed as an alternative surgical option to treat these fractures. The objective of this study was to assess the comparative endurance of both devices.

Method

The dynamic compression screw (DCS) and Biomet Matthews Nail (BMN) were implanted into composite femurs, which were subsequently cyclically loaded using a materials testing machine. Simulated fractures were applied to each femur prior to the application of load. Either a Y type fracture or a transverse osteotomy was prepared on each composite femur using a jig to enable consistent positioning of cuts.

Results

The Biomet Matthews Nail demonstrated a greater endurance limit load over the dynamic compression screw in both fracture configurations.

Conclusion

The distal locking screws pass through the Biomet Matthews Nail in a unique "cruciate" orientation. This allows for greater purchase in the bone of the femoral condyle and potentially improves the stability of the fracture fixation. As these fractures are usually in weak osteoporotic bone, the Biomet Matthews Nail represents a favourable surgical option in these patients.

Arthroscopically-assisted removal of retrograde intramedullary femoral nails

Retrograde nailing of femoral shaft fractures has become more prevalent as a result of its growing acceptance and familiarity to orthopaedic surgeons. Nail removal is occasionally indicated, which may require a formal arthrotomy. We describe an arthroscopic removal technique that has several advantages. The percutaneous technique imparts less morbidity than a more extensive arthrotomy. More importantly, additional intra-articular pathology can be thoroughly assessed and treated, such as meniscal tears and chondral injury, which may have occurred at the time of injury. These are potential causes of knee pain, which usually cannot be properly diagnosed without arthroscopy. Our findings also support the existence of a stable fibrous cap, which forms over the entry portal of a well-seated retrograde femoral nail as well as no evidence of intra-articular metallosis.

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.

The effect of locked distal screws in retrograde nailing of osteoporotic distal femur fractures: a laboratory study using cadaver femurs

OBJECTIVES

To examine the effects of locked distal screws in retrograde nails used in unstable osteopenic distal femur fractures.

DESIGN

Biomechanical testing of paired human cadaveric femurs.

INTERVENTION

Seven matched pairs of embalmed, moderately osteopenic cadaver femurs were instrumented with 12-mm intramedullary nails in a statically locked, retrograde fashion. One femur of each pair had locked distal screws and the other femur had unlocked distal screws. A 2.5-cm gap of bone was cut nine centimeters from the distal condyles to simulate an unstable fracture. The locked distal screw nails were compared to unlocked distal screw nails for collapse of the fracture gap, medial-lateral and anterior-posterior translation of the nail within the fracture site, and fracture angulation. The femurs were axially loaded, cycled, and then loaded to failure.

MAIN OUTCOME MEASURES

Motion at the fracture site with axial cyclic loading and site of failure when loaded to failure.

RESULTS

After cycling, both locked distal screw and unlocked distal screw nails demonstrated several millimeters medial and anterior translation within the fracture site and approximately 1 mm collapse of the fracture gap. Although no statistically significant differences were found, the locked distal screw nails had less anterior and medial translation, angulation, and collapse of the fracture gap after cycling. Loads to failure were similar for both locked distal screw and unlocked distal screw nails. It was noted that proximal femur failure occurred at the level of the proximal screw hole in the nail at the subtrochanteric level in 7 (4 locked distal screws and 3 unlocked distal screw groups) of the 14 samples. Four other samples failed through the intertrochanteric region (2 locked distal screw and 2 unlocked distal screw groups) and the remainder within the distal fragment by fracture of the femur along the medial cortex.

CONCLUSIONS

Although most differences in fixation stability were not significant, the locked distal screw nails exhibited less fracture collapse and anterior and medial translation of the nail at the fracture site than the unlocked distal screw nails. The degree of varus angulation after cyclic loading was also less for the locked distal screw nails. The length of the nail chosen should avoid having proximal locking screws distal to the lesser trochanter, thus averting proximal femur stress risers and fractures.

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.