Determination of sagittal alignment measurements in distal femurs

Titanium versus stainless steel alloy bridge plates for distal femur fractures: Does callus form earlier with titanium?

INTRODUCTION

Distal femur fractures account for 3-6% of all femur fractures. Internal fixation of most distal femur fractures with an anatomic lateral locking plate should permit some motion at the metaphyseal portion of the fracture when secondary bone healing is planned by the operating surgeon. While several studies have been performed evaluating union rates for distal femur fractures with stainless steel and titanium plates, the timing of callus formation between stainless steel and titanium implants used as bridge plates for distal femur fractures (AO/OTA 33-A and -C) has been investigated to a lesser extent. We hypothesize that callus will be visualized earlier with post-operative radiographs with titanium versus stainless steel bridge plates.

METHODS

We retrospectively reviewed a consecutive cohort of patients over 18 years of age with acute AO/OTA 33-A and 33-C fracture patterns treated with an isolated stainless steel or titanium lateral bridge plate within 4 weeks of injury by a single fellowship-trained orthopedic trauma surgeon from 2011 to 2020 at one academic Level 1 trauma center. An independent, fellowship-trained orthopedic trauma attending surgeon reviewed anterior-posterior (AP) and lateral radiographs from every available post-operative clinic visit and graded them using the Modified Radiographic Score for Tibia (mRUST).

RESULTS

Twenty-five subjects were included in the study with 10 with stainless steel and 15 with titanium plates. There were no significant differences in demographics between both groups, including age, sex, BMI, injury classification, open versus closed, mechanism, and laterality. Statistically significant increased mRUST scores, indicating increased callus formation, were seen on 12-week radiographs (8.4 vs. 11.9, p = 0.02) when titanium bridge plates were used. There were no statistically significant differences in mRUST scores at 6 or 24-weeks, but scores in the titanium group were higher in at every timepoint.

DISCUSSION

In conclusion, we observed greater callus formation at 12 weeks after internal fixation of 33-A and 33-C distal femur fractures treated with titanium locked lateral distal femoral bridge plates compared to stainless steel plates. Our data suggest that titanium metallurgy may have quicker callus formation compared to stainless steel if an isolated, lateral locked bridge plate is chosen for distal femur fracture fixation.

Locked Lateral Plating Versus Retrograde Nailing for Distal Femur Fractures: A Multicenter Randomized Trial

OBJECTIVES

The 2 main forms of treatment for distal femur fractures are locked lateral plating and retrograde nailing. The goal of this trial was to determine whether there are significant differences in outcomes between these forms of treatment.

DESIGN

Multicenter randomized controlled trial.

SETTING

Twenty academic trauma centers.

PATIENTS/PARTICIPANTS

One hundred sixty patients with distal femur fractures were enrolled. One hundred twenty-six patients were followed 12 months. Patients were randomized to plating in 62 cases and intramedullary nailing in 64 cases.

INTERVENTION

Lateral locked plating or retrograde intramedullary nailing.

MAIN OUTCOME MEASUREMENTS

Functional scoring including Short Musculoskeletal Functional Assessment, bother index, EQ Health, and EQ Index. Secondary measures included alignment, operative time, range of motion, union rate, walking ability, ability to manage stairs, and number and type of adverse events.

RESULTS

Functional testing showed no difference between the groups. Both groups were still significantly affected by their fracture 12 months after injury. There was more coronal plane valgus in the plating group, which approached statistical significance. Range of motion, walking ability, and ability to manage stairs were similar between the groups. Rate and type of adverse events were not statistically different between the groups.

CONCLUSIONS

Both lateral locked plating and retrograde intramedullary nailing are reasonable surgical options for these fractures. Patients continue to improve over the course of the year after injury but remain impaired 1 year postoperatively.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Sagittal mechanical ratio: A novel technique to define sagittal alignment of the femur independent of distal anatomic landmarks

BACKGROUND

Radiographic measurements to study sagittal alignment in the setting of knee are frequently difficult to evaluate due the presence of a prosthesis or implant that obscures traditional radiographic landmarks. In this paper we present a novel method of determining sagittal femoral alignment in the presence of obscuring implants.

METHODS

98 full-length femoral radiographs were reviewed and divided into two groups. In Group 1, the Distal Mechanical Point (DMP) was used to calculate the Distal Mechanical Ratio (DMR), defined as the ratio of the linear distance from the DMP to the anterior cortical axis divided by the distance from the anterior cortical axis to posterior condylar cortex. In group 2, the sagittal mechanical axis was measured using the true DMP (tDMP) and then separately measured using the DMR to find the calculated DMP (cDMP), and the angular variance between the calculated (cSMA) and true (tSMA) sagittal mechanical axis was calculated, as well as the linear distance between the tDMP and cDMP. Twenty additional patients with knee replacements were then selected and two observers used a cSMA to determine a femoral prosthesis flexion angle (FPFA), with intraobserver correlation calculated.

RESULTS

The mean DMR was found to be 0.24, with high intraobserver correlation and normal distribution. Validation of the model demonstrated angular variance between tSMA and cSMA less than 1 degree and linear distance between tDMP and cDMP less than 1 mm. Calculation of cCMA in the presence of total knee arthroplasty revealed very strong intraobserver correlation of 0.89.

CONCLUSION

The Distal Mechanical Ratio reliably predicted the true Sagittal Mechanical Axis within 1 degree and true Distal Mechanical Point within 1 mm, indicating that it may be a valuable tool for evaluating sagittal femoral alignment in cases where anatomic landmarks may be absent or obscured.

Using Blumensaat's line to determine the sagittal alignment of the distal femur

BACKGROUND

A coherent measurement approach for sagittal alignment of the distal femur after fracture reduction or distal femur osteotomies is not available. The present study aims to introduce a new method using Blumensaat's line and tangent lines to the femoral cortexes to determine the sagittal alignment of the distal femur.

METHODS

113 patients who had true lateral knee radiographs were included. All of the radiographs were evaluated by one fellowship-trained knee surgeon and one radiologist using the PACS system. The Blumensaat's line was determined on the true lateral knee radiographs. Then, three long lines were drawn on the distal third of the femoral shaft. The first line is tangent to the anterior cortex of the femur, the second line is along with the anatomical axis of the femur, and the third line is tangent to the posterior cortex of the femur. The angles between Blumensaat's line and these lines were measured. Intraclass Correlation Coefficient (ICC) was used to measure the strength of inter-and intra-rater agreement.

RESULTS

The mean angle between the Blumensaat's line and the anatomical axis of the femur was 35.4 ± 3°. The mean angle between the Blumensaat's line and the line tangent to the anterior femoral cortex and the line tangent to the posterior femoral cortex were 34.5 ± 3° and 35.2 ± 3°, respectively. Excellent inter-and intra-rater reliabilities were observed between the measurements (ICC = 0.96 and ICC = 0.98, respectively). The angle between the Blumensaat's line and the line tangent to the posterior femoral cortex was significantly higher in participants aged < 38 years (p = 0.049). No other significant association was found between the angles and demographic characteristics of the patients.

CONCLUSIONS

The expected mean angles between the Blumensaat's line and the distal femur were 34.3 to 35.4 degrees. This finding could be useful to determine the normal sagittal alignment of the distal femur.

LEVEL OF EVIDENCE

II.

Is retrograde nailing superior to lateral locked plating for complete articular distal femur fractures?

INTRODUCTION

Nonunion rates for distal femur fractures treated with lateral locked plating (LLP) remains as high as 18-22% despite significant advances with implant design and construct modulation. However, whether treatment of distal femur fractures with rIMN has improved outcomes compared to LLP has not been well characterized. The purpose of this study was to compare outcomes of complete articular distal femur fractures (AO/OTA 33-C) treated with either LLP or rIMN.

METHODS

106 distal femur fractures in 106 patients between January 2014 and January 2018 were identified. Medical records were reviewed to collect patient age, gender, body mass index, sagittal and coronal plane alignment on immediate postoperative radiographs, time to union, incidence of nonunion, and incidence of secondary operative procedures for repair of a nonunion.

RESULTS

Of 106 patients, 50 underwent rIMN and 56 underwent LLP. The mean age at the time of injury was 51 years (21 to 86 years) and there were 55 males. Average coronal alignment of 83.7° of anatomic lateral distal femoral angle (aLDFA) and sagittal alignment of <1° of apex anterior angulation in the rIMN group. In the LLP group there was an average of 87.9° of aLDFA and 1.9° of apex anterior angulation (p = .005 and p = .36). Average time to union in the rIMN group was 6 months and 6.6 months in the LLP group (p = .52). Incidence of nonunion in the rIMN group was 11.8% and 27.5% in the LLP group (p = .008). There were 8 secondary procedures for nonunion in the rIMN group and 18 in the LLP group (p = .43).

CONCLUSIONS

Our results demonstrated a higher nonunion rate and coronal plane malalignment with LLP compared to rIMN. While prospective data is required, rIMN does appear to be an appropriate treatment for complete articular distal femur fractures with a potentially decreased rate of nonunion .

External Fixator-Assisted Reduction of Distal Femur Fractures: A Technical Trick

Restoration of anatomical alignment while preserving the soft-tissue envelope around the fracture site remains a challenge during distal femur fracture fixation. Although the lateral distal femoral locking plate allows surgeons to achieve adequate bony stability, their application has been associated with malalignment leading to inferior outcomes. We propose a biologically friendly, percutaneous technique that sequentially reduces and aligns distal femur fractures with an anterior external fixator before definitive fixation with a lateral distal femoral locking plate.

Is the compressive nail method capable of accelerating bone union in patients with femoral distal diaphysis fracture?

OBJECTIVES

This study was conducted to evaluate clinically and radiologically the patients for whom compressive and non-compressive intramedullary nails were applied and to analyse the compression effectiveness in adult femur distal diaphysis fractures.

HYPOTHESIS

The compressive locked nails shortened the union period in the distal diaphysis fractures, and it was found to be an effective method, as the pseudoarthrosis rate was lower.

MATERIAL AND METHODS

A retrospective study was conducted among 59 patients for whom the compressive and non-compressive IMNs were applied to treat femur distal diaphysis fractures. Thirty-one for whom the non-compressive IMN was applied were categorised as group I, and 28 for whom the compressive nail was applied were categorised as group II. Finite element analysis was performed using 1.5mm compression, and a mean stress value of 34.67Mpa.

RESULTS

The mean values of union period were calculated as 13.6±2.4 weeks (range: 11-20 months) and functional score was 79.2, respectively in group I, and they were evaluated as a good grade. In group II, the respective mean values of union period were 11.5±2.6 weeks (range: 10-17 months) and functional score was 86, and they were evaluated as excellent.

CONCLUSION

Radiological and functional scores were determined to be better with interlocking compressive nails and shortened the fracture union period in the follow-up in adult femur distal diaphysis fractures.

LEVEL OF EVIDENCE

III; retrospective cohort study.

Measurement of three-dimensional morphological characteristics of the calcaneus using CT image post-processing

Background

Although computed tomography (CT) with three-dimensional (3D) rendering of the calcaneus is used for diagnostic evaluation of disorders, morphological measurements for the calcaneus are mostly based on a two-dimensional plane. The purposes of this study were to design a method for 3D morphological measurements of the normal calcaneus based on CT post-processing techniques, to measure morphological parameters in the male and female groups and describe gender differences of the parameters, and to investigate the reliability of such measurements.

Methods

One hundred and seventy-nine patients (83 men and 96 women) with a mean age of 40.6 (range, 21 to 59) years who underwent CT scans for their feet were reviewed retrospectively. The 3D structure of a normal calcaneus after shaded surface display reconstruction was extracted by interactive and automatic segmentation. Morphological measurements were achieved by means of a 3D measurement method based on CT image post-processing. Lengths and heights of the main parts of the calcaneus, Gissane’s angle, Böhler’s angle and the area of articular facet were worked out in 3D space. Gender-related size differences of parameters were compared using analysis of covariance (ANCOVA), adjusting for body height. Intra-observer and inter-observer reliabilities were assessed using intraclass correlation coefficients (ICCs) and the root mean square standard deviation (RMS-SD) for precision study.

Results

A large range of measurement values was found. Only the length of the anterior process was without gender difference (p > 0.05). The other parameters in the male group were greater than those in the female group (p < 0.01 for each, ANCOVA). All parameters had excellent reliability and reproducibility (ICC > 0.8). Precision was acceptable for intra-observer RMS-SD (linear, angular and areal measurements no more than 0.6 mm, 1.2° and 0.25 mm², respectively). Inter-observer RMS-SD ranged from 0.4 to 1.6 mm for linear measurements, 1.2 to 2.5° for angles and 0.24 to 0.40 mm² for areas.

Conclusions

Three-dimensional morphological measurement based on a CT post-processing technique was highly reliable and repeatable for calcaneal anatomic morphological measurement. The current data will be helpful for anatomic reduction of calcaneal fractures and calcaneal malunion.