Treatment of femoral shaft fractures with a titanium intramedullary nail

Investigating reverse butterfly fractures: An experimental approach and application of fractography

Butterfly fractures are expected to form with the transverse portion on the tension side and the wedge portion on the compression side of a bent bone, however wedges have also been observed in the reverse orientation and are reported to be frequent in concentrated 4-point bending. To investigate how these fractures form, concentrated 4-point bending experiments were performed on nine human femora and documented using high-speed video. Videos showed the wedge portion formed as fracture initiated in tension, branched obliquely, then curved to terminate on the tension face. The transverse portion formed as a crack traveled between the curved fracture branch and the compression face. Fractography was also applied to evaluate fracture surfaces. At least one fractography feature was present in all femora and 32/35 bone fragments examined. Fracture propagation sequences interpreted using fractography matched those observed on video, demonstrating the utility of this method for evaluating complex fracture patterns.

Influence of screw combination and nail materials in the stability of anterograde reamed intramedullary nail in distal femoral fractures

Intramedullary nailing (IM) is a technique universally accepted to treat femoral diaphyseal fractures. The treatment of fractures located in the distal third remains a controversial issue though. A finite element model of the femur has been developed, analyzing distal fractures with several gap sizes combined with different interlocking combinations of distal screws with one oblique screw proximally to stabilize the intramedullary nail. The mechanical strength of the nail against bending and compression efforts was also studied. Beside the FE simulations, a clinical follow-up of 15 patients, 6 males and 9 females, with mean age of 53.2 years was carried out. Localizations of fractures were 10 in the right femur and 5 in the left femur, respectively. A fairly good correspondence agreement between clinical results and the simulated fractures in terms of gap size was found. Non-comminuted fractures had a mean consolidation time of 20.5 weeks (4.8 months), a tendency corresponding well to the mobility obtained in the FE simulations; Comminuted fractures on the other hand exhibited a higher mean consolidation period of 22.2 weeks (5.2 months) secondary to the excessive mobility at fracture site obtained by means of FE simulations. The best stability at fracture site was found for the system with three distal screws and the system with two distal screws placed medial lateral. The highest leverage of distal screws was obtained maximizing the distance between them and choosing the coronal plane for their orientation. The results obtained with both nail materials (stainless steel and titanium alloy) show a higher mobility when using titanium nails. Steel nails provide stiffer osteosyntheses than the titanium nails. In conclusion, the best screw combination in terms of stability to produce fracture healing and the least difficulties during treatment is the one which had one oblique proximal screw with two distal lateral screw implanted in the coronal plane.

[Development and clinical application of a new type of intramedullary nail tail cap]

Objective

To develop a new type of tail cap for closing the tail of the central hole of the interlocking intramedullary nail so as to reduce difficulty in implantation of the tail cap into intramedullary nail, and ensure the accuracy of implantation, as well as reduce unnecessary operation time.

Methods

In 2014, the new type of intramedullary nail tail cap ("new tail cap" for short) was successfully developed, and has been granted national utility model patent. A randomized controlled clinical trial was conducted in 34 patients with non pathological femoral shaft fractures treated between August 2014 and March 2016. The patients were randomly divided into groups A and B, 17 patients each group. There was no significant difference in gender, age, side, body mass index, cause of injury, injury to operation time, and fracture AO classification between groups ( P>0.05), with comparability. All patients underwent fixation with interlocking intramedullary nail, and the new tail cap and original tail cap were used in groups A and B respectively. The blood loss and operation time during tail cap implantation, fracture healing time, and complications were recorded and compared between 2 groups; the limb function was evaluated by Klemm function evaluation standard.

Results

The blood loss and operation time during tail cap implantation of group A [(3.5±0.8) mL and (10.57±3.15) s] were significantly less than those of group B [(5.5±1.7) mL and (21.99±6.90) s] ( t=-8.281, P=0.010; t=-10.743, P=0.009). All new tail caps were successfully implanted by one-time in group A, and the one-time success rate was 100%; the original tail cap exfoliation occurred in 3 cases of group B, and the one-time success rate was 82.4%. All the patients were followed up 6-16 months (mean, 9.7 months); there was no deep infection, loosening or breakage of internal fixation, and other serious complications. The time of fracture healing was (16.4±3.2) weeks in group A and (15.8±3.5) weeks in group B, showing no significant difference ( t=0.514, P=0.611). At last follow-up, according to the Klemm function evaluation standard, the results were excellent in 14 cases and good in 3 cases in group A, and were excellent in 11 cases and good in 6 cases in group B, showing no significant difference between 2 groups ( χ²=0.142, P=0.707).

Conclusion

The new type of femoral intramedullary nail tail cap can simplify operation, shorten operation time, and reduce blood loss, and it has satisfactory effectiveness.

Complications following implant removal in patients with proximal femur fractures - an observational study over 16 years

BACKGROUND

Fractures of the proximal femur commonly occur but the majority of orthopaedic surgeons do not consider general hardware removal as a routine necessity. Indications and time interval for hardware removal in this special selected patient group is still controversial. Therefore we performed a retrospective study to address the following questions: 1) Is there a difference between the medically- (infection, mechanical problems, implant failure) and non-medically indicated group (patients demand, meteoro-sensitivity, foreign body sensation) in relation to complications? 2) Is there a correlation regarding time interval between implantation and removal comparing these two groups? 3) Is there a context related refracture rate? 4) Should non-medically indicated implant removal (IR) be performed due to persistent pressure from the patient?

HYPOTHESIS

We hypothesized that non-medically indicated implant removals should be avoided due to a significantly higher number of associated complications.

PATIENTS AND METHODS

A total of 371 consecutive patients with 424 hardware removal procedures following a proximal femur fracture, between 08/1992 and 11/2008, have been included. Study population was divided into two groups according to their indication for implant removal: medically indicated group (MIR) consisted of 299 patients (80.59%) and 72 patients (19.41%) were assigned to the non-medically indicated (NMIR) group.

RESULTS

In the NMIR subgroup a total of (n = 21) 28% complications occurred compared to 11.46% in the MIR subgroup; (P < 0.005), 86.51% of IR in the MIR group were performed within 1.5 years, compared to 79.17% in the NMIR group after 2 to 3.5 years (NS). In the MIR group 1 refracture occurred, compared to 4 in the NMIR group (NS).

CONCLUSION

Non-medically indicated implant removal should be avoided due to the higher complication rate of 28%. Surgeons and patients should be aware of the imminent complications and therefore implant removal should only be performed for good medical reasons.

LEVEL OF EVIDENCE

Level IV. Historical case study.

Femoral neck fracture following hardware removal

It is uncommon for femoral neck fractures to occur after proximal femoral hardware removal because age, osteoporosis, and technical error are often noted as the causes for this type of fracture. However, excessive alcohol consumption and failure to comply with protected weight bearing for 6 weeks increases the risk of femoral neck fractures.This article describes a case of a 57-year-old man with a high-energy ipsilateral inter-trochanteric hip fracture, comminuted distal third femoral shaft fracture, and displaced lateral tibial plateau fracture. Cephalomedullary fixation was used to fix the ipsilateral femur fractures after medical stabilization and evaluation of the patient. The patient healed clinically and radiographically at 6 months. Despite conservative treatment for painful proximal hardware, elective hip screw removal was performed 22.5 months after injury. Seven weeks later, he sustained a nontraumatic femoral neck fracture.In this case, it is unlikely that the femoral neck fracture occurred as a result of hardware removal. We assumed that, in addition to the patient's alcohol abuse and tobacco use, stress fractures may have attributed to the femoral neck fracture. We recommend using a shorter hip screw to minimize hardware prominence or possibly off-label use of an injectable bone filler, such as calcium phosphate cement.

The effectiveness of the antegrade reamed technique: the experience and complications from 415 traumatic femoral shaft fractures

This retrospective study presents the experience gained through use of reamed femoral nails and reports results and respective complications. This study included 415 femur fractures (312 men and 101 women with a mean age of 27.8 years) that were treated from 1993 to 2004. The fractures were classified according to AO, and 74 open fractures were included and typed according to the Gustilo classification. Dynamic nailing was performed for nearly all type A fractures and static nailing for types B and C. After a mean follow-up of 1.5 years, union rate was 97.8%. The complications were: 9 non-unions, 14 delayed-unions, 4 torsional malunions, 6 limb length discrepancies (shortening) and 30 nerve pareses due to traction. Deep venous thrombosis (DVT) occurred below the knee in 4 patients, while there were recorded 3 pulmonary and 2 fat embolisms, 1 superficial and 1 deep infection. There were 28 broken screws identified postoperatively. Logistic regression analysis revealed that type B and C were associated with increased risk of complications, with respective odds ratios of 3.1 (95% CI = 1.3–7.2, P = 0.011) and 4.3 (95% CI = 1.8–10.3, P = 0.001) when compared to type A patterns. All patients returned to their activities in a mean time of 10 months. Intramedullary nailing is still the treatment of choice for femoral shaft fractures, but knowledge of potential complications and their association with certain fracture patterns is needed.

The influence of osteoporosis in femoral fracture healing time

AIM

In order to assess the effect of osteoporosis on healing time, the files of 165 patients with femoral shaft fractures that were treated in our institution with locked-reamed intramedullary nailing were retrospectively reviewed.

PATIENTS AND METHODS

Patients with open fractures, pathological fractures, revision surgery, severe brain injuries and prolonged ITU stay were excluded. In all patients the Singh-index score for osteoporosis and the canal bone ratio (CBR) were assigned. Sixty-six patients fulfilled the inclusion criteria. Patients were divided into two groups; group A (29 patients) consisted of patients over 65 years old with radiological evidence of osteoporosis and group B (37 patients) of patients between 18 and 40 years old with no signs of osteoporosis.

RESULTS

In all group A patients Singh score < or =4 and CBR>0.50 were assigned, suggesting the presence of osteoporosis, whereas all group B patients were assigned with Singh score > or =5 and CBR<0.48. Fractures of group A healed in 19.38+/-5.9 weeks (12-30) and in group B 16.19+/-5.07 weeks (10-28), P=0.02.

CONCLUSIONS

Fracture healing of nailed femoral diaphyseal fractures is significantly delayed in older osteoporotic patients. Further studies are required to clarify the exact impact of osteoporosis in the whole healing process.

An intramedullary nail with multifunctional interlocking for all types of fracture in both femurs

OBJECTIVE

A femoral compound interlocking intramedullary nail (FCIIN) was designed to treat all types of fractures between the trochanter and epicondyle of both femurs. It could substitute for femoral interlocking intramedullary nails (FIIN) at five points.

METHODS

According to the morphological characteristics of the femoral medullary canal, the nail is designed to accommodate a 1250 mm radius of radian and a 135° neck-shaft angle. Three interlocking holes of 6.5 mm diameter are located at the proximal end of the FCIIN, making crossing of the screws possible. The hole is designed to be vertical (90°) or oblique (45° upper or lower). At the tip of the proximal interlocking screws, whose root diameter gradually increases from 3.5 mm to 6.5 mm, a self-tapping cancellous screw is placed. There are two types of distal interlocking screws. One is a fine thread and the other a bolt screw. Two interlocking holes and a recess 4.5 mm in diameter are located at the distal end of the FCIIN. Under biomechanical destructive testing, the proximal interlocking screw device has satisfactory strength and reasonable structure. A total of 47 patients (31 males and 16 females, with an average age of 39.83 years) with femoral fractures were assessed in this study. Fourteen cases were diagnosed as intertrochanteric, 7 as subtrochanteric, 18 as femoral shaft, and 8 as supracondylar fractures. All 47 patients were treated with the FCIIN.

RESULTS

Of the 47 patients, anatomic reduction was achieved in 34, good reduction in 11, and forced line reduction in 2 cases. Reduction was excellent or good in 95.87% of the fractures. The removal time of the FCIIN was 12 to 21 months (average, 16.9 months). One patient with an intertrochanteric fracture who had a fixation failure combined with non-union achieved healing with an external fixator at 18 months. Failure to insert the distal interlocking screws occurred in 5 patients but did not affect bone healing.

CONCLUSION

The FCIIN is a useful device in the treatment of a variety of femoral fractures.

Segmentation of the canine population in different femoral morphological groups

OBJECTIVE

The incidence of femoral traumatology and hip dysplasia shows the need to design canine specific femoral implants in veterinary surgery. A good knowledge of femoral morphology, and particularly of intra-species variability, is required to develop a well-adapted canine femoral intramedullary implant. The aim of this study is to evaluate the morphological variability of the canine femur and to propose a segmentation of this population.

PROCEDURE

This study proposes different possibilities for the segmentation of a canine population of 103 dogs of various common breeds in relation to their femoral morphology. These segmentations were obtained with a statistical methodology, which takes into account 24 measured and calculated morphological parameters of 206 canine femurs.

RESULTS

The segmentation of this canine population into four or six homogeneous groups related to the femoral morphology were the two most relevant solutions. The total length of the femur and the femoral head diameter were the best discriminant parameters for this segmentation.

CONCLUSION

Knowledge of the variability of the femoral morphology in the canine species and the possibility of splitting the canine population into homogeneous morphological groups are useful for the design of specific canine femoral implants. The femoral morphological profiles of each group constitute an essential database for fitting the best orthopedic implant to the bone.

Intramedullary nailing of the lower extremity: biomechanics and biology

The intramedullary nail or rod is commonly used for long-bone fracture fixation and has become the standard treatment of most long-bone diaphyseal and selected metaphyseal fractures. To best understand use of the intramedullary nail, a general knowledge of nail biomechanics and biology is helpful. These implants are introduced into the bone remote to the fracture site and share compressive, bending, and torsional loads with the surrounding osseous structures. Intramedullary nails function as internal splints that allow for secondary fracture healing. Like other metallic fracture fixation implants, a nail is subject to fatigue and can eventually break if bone healing does not occur. Intrinsic characteristics that affect nail biomechanics include its material properties, cross-sectional shape, anterior bow, and diameter. Extrinsic factors, such as reaming of the medullary canal, fracture stability (comminution), and the use and location of locking bolts also affect fixation biomechanics. Although reaming and the insertion of intramedullary nails can have early deleterious effects on endosteal and cortical blood flow, canal reaming appears to have several positive effects on the fracture site, such as increasing extraosseous circulation, which is important for bone healing.

Increasing bending strength of tibial locking screws: mechanical tests and finite element analyses

BACKGROUND

Healing of tibial fractures treated by locked nailing is threatened by locking screw failure. However, the effects of the design factors of the screws on their mechanical strength have rarely been studied.

METHOD

Three-point bending tests and finite element analyses were used to investigate the bending strength of five types of commercially available tibial locking screws and two types of specially designed screws. Yielding strength and fatigue life measured in bending tests were correlated to total strain energy and maximal tensile stress computed in finite element analyses. Parametric analysis and design optimization were done according to the Taguchi method. Validation studies to assess the stress rising effect of the threads on the fatigue strength were conducted in two types of new screws made of either stainless steel or titanium alloy.

FINDINGS

The yielding strength of the screws was closely related to their total strain energy, and the logarithm of the fatigue life was closely related to the maximal tensile stress with correlation coefficients of -0.95 and -0.90, respectively. Parametric studies indicated that fatigue strength of the screws was affected mainly by inner diameter (contribution, 63.8%) and root radius (27.8%). The yielding strength was determined primarily by inner diameter (88.5%). Titanium screws had a longer fatigue life than stainless steel screws, especially in screws with larger root radii.

INTERPRETATION

A screw's strength is closely related to its design factors. Finite element models, which can reliably reflect the mechanical strength of screws can save time and effort during screw design. Larger root radius can effectively improve the fatigue strength, especially for titanium screws as compared with stainless steel screws.

Mechanical study of the safe distance between distal femoral fracture site and distal locking screws in antegrade intramedullary nailing

OBJECTIVE

To determine the safe distance for distal femoral fractures relative to the distal locking screws in antegrade intramedullary femoral nailing using a currently available titanium alloy nail design.

DESIGN

Cyclic (fatigue) mechanical testing study.

SETTING

Biomechanics laboratory.

INTERVENTION

Intramedullary nailing of left synthetic fiberglass composite femora with type 32/33-C fractures at 1, 2, 3, and 4 cm from the more proximal of the distal locking screws.

MAIN OUTCOME MEASUREMENT

The number of loading cycles to failure of the nail.

RESULTS

A load level of 700 N through the femoral mechanical axis was validated as adequate to cause fatigue failure within 200,000 cycles in slotted stainless- steel nails. In the nonslotted titanium alloy nails, this load level caused failure in only 1 of 3 nails with a fracture at 2 cm from the more proximal of the 2 distal locking screws and in 2 of 3 nails with a fracture at 1 cm from the more proximal of the 2 distal locking screws. All of the other nails did not fail >1 million cycles.

CONCLUSIONS

Under laboratory conditions, it is safe to assume that an antegrade titanium alloy nail will survive 1 million compression/bending cycles when the fracture is > or = 3 cm from the more proximal of the 2 distal locking screws.

Treatment of femoral shaft aseptic nonunion associated with broken distal locked screws and shortening

BACKGROUND

This retrospective study investigated the treatment of femoral shaft aseptic nonunions associated with broken distal locked screws and shortening.

METHODS

In this study, 11 femoral shaft aseptic nonunions associated with both broken distal locked screws and shortening in 11 consecutive adult patients were treated. All nonunions were associated with at least 1.5 cm (range, 1.5-3.5 cm) shortening. These nonunions were treated by removal of locked nails, one-stage femoral lengthening, static locked nail stabilization, and corticocancellous bone graft supplementation. Postoperatively, ambulation with protected weightbearing was encouraged as early as possible.

RESULTS

Ten nonunions were followed up for a median of 4.1 years (range, 1.8-5.5 years), and nine fractures healed at a median of 4 months (range, 3-6 months). The nonunion case had broken locked screws again at 5 months and was treated with exchange nailing. The fracture healed uneventfully at 4 months. No other complications occurred.

CONCLUSIONS

The key to removal of broken screws is withdrawal of the nail slightly to release the incarcerated broken screw end. The screw end then is pushed out with a used Knowles' pin or a smaller screwdriver under image intensifier guidance. Concomitant one-stage femoral lengthening to treat nonunion with shortening has a high success rate.