CT analysis of femoral malrotation after intramedullary nailing of trochanteric fractures

Impact of operative position on rotational alignment after intramedullary nailing of trochanteric fractures: a comparative analysis of lateral decubitus versus supine position

BACKGROUND

Fixation of trochanteric fractures with an intramedullary nail in a non-physiological position can cause poor functional outcomes. The aim of this study is to evaluate the effect of intraoperative patient position on rotational alignment in intramedullary nail fixation of trochanteric fractures.

METHODS

The femoral rotational alignment of 84 trochanteric fracture patients who underwent intramedullary nailing was measured by computed tomography (CT) images. Patients were divided into two groups: the supine position on the fracture table (FT) (Group 1, n = 42) and the lateral decubitus (LD) position (Group 2, n = 42). Femoral malrotation angles were measured and divided into three subgroups: insignificant, significant, and excessive. The number of intraoperative fluoroscopy images, preparation time, surgery time, and anesthesia time in both groups were compared.

RESULTS

The malrotation degrees of patients in Group 1 ranged from 17° external rotation (ER) to 57° internal rotation (IR), with a mean of 10° IR. Of the patients in Group 1, 27 were insignificant, 5 were significant, and 10 were in the excessive subgroup. The malrotation degrees of patients in Group 2 ranged from 33° ER to 47° IR, with a mean of 11° IR. Of the patients in Group 2, 21 were insignificant, 12 were significant, and 9 were in the excessive subgroup. There was no statistically significant relationship between patient position and malrotation angle. The number of intraoperative fluoroscopy images, preparation time, and anesthesia time were statistically lower in Group 2. There was no statistically significant difference between Group 1 and Group 2 in terms of surgery time.

CONCLUSION

Intramedullary nailing in the LD position is a reliable and practical surgical method in the treatment of femoral trochanteric fractures since there is no need for the use of a FT, the surgeon is exposed to less radiation, there is no risk of complications related to the traction of the FT, and there is a shorter operation time.

Measurement Method of Femoral Anteversion During Surgery for Trochanteric Fractures

The acceptable range of bilateral differences in the femoral rotation is ≤15°, as a difference in femoral rotation over 15° may cause functional disturbance. However, femoral trochanteric fractures do not have clear indicators of rotation during surgery. This study aimed to verify the accuracy of this novel method for measuring femoral anteversion during trochanteric fracture surgery. From August 2022 to August 2024, this study prospectively included patients with femoral trochanteric fractures treated using a cephalo-medullary nail with a lag-screw neck-shaft angle of 125°. During surgery, direct intraoperative anteversion (DIAV) was measured using the hip post axis in the lateral hip image based on a tabletop plane parallel to the floor. DIAV was then converted to corrected intraoperative anteversion (CIAV) using a quick chart derived from a graph of the axial projection. The accuracy was analyzed by comparing CIAV with computed tomography anteversion (CTAV) measurements obtained after surgery. One hundred patients (25 male, 75 female) with a mean age of 86.7 years (range: 67-104 years) were included in this study. According to the Orthopaedic Trauma Association classification, there were 66 patients classified as A1, 23 as A2, and 11 as A3. The mean DIAV and CIAV were 8.2°±8.2° and 9.6°±9.7°, respectively, while the mean CTAV was 10.3°±10.4°. The median difference between CIAV and CTAV was 3° (range: 0°-9°), with 84 patients exhibiting differences of ≤5°. No significant differences were found between CIAV and CTAV (p = 0.054), whereas DIAV was significantly lower than CTAV (p < 0.001). CIAV and CTAV were strongly correlated (r = 0.936, p < 0.001). The Bland-Altman plot between CIAV and CTAV revealed that 98 patients were within the limits of agreement, and the plot distribution showed no trend. The measurement method for assessing femoral anteversion using the hip post axis on the lateral hip image based on a tabletop plane parallel to the floor during surgery demonstrated sufficient accuracy for indicating anteversion in femoral trochanteric fractures.

Accuracy of the Lesser Trochanter Profile as a Marker of Femoral Rotation: Computed Tomography-Based Study of 1,722 Femora

BACKGROUND

The lesser trochanter (LT) profile is an often-used marker for proximal femoral rotation, particularly during the operative fixation of femoral fractures. Previous studies have come to conflicting conclusions about its reliability for this purpose.

METHODS

The SOMA (Stryker Orthopaedic Modeling and Analytics) database (Stryker) was used to identify 1,722 computed tomographic (CT) scans of whole femora. Each femur was taken through an 80° rotational arc in 2.5° increments, and the LT profile was constructed for each position. These 56,826 LT profile measurements were then correlated with the femoral rotation.

RESULTS

Across the arc of motion studied, the LT correlated weakly with proximal femoral rotation (R 2 = 0.32). There was a 35° arc, between 10° and 45° relative external rotation of the proximal femur, within which the LT profile only changed by 1 mm. The mean overall femoral anteversion was 21.2°, and women tended to have more femoral anteversion (23.9°) than men (19.2°). On average, men had a 1.6-mm more prominent LT than women. Side-to-side differences in femoral anteversion as well as LT position and size were not significant or were clinically unimportant.

CONCLUSIONS

A large-scale, CT-based study shows that the LT profile is a less reliable marker of proximal femoral rotation than previously thought. This is true particularly if there is relative external rotation of the proximal femur, where the proximal femur can undergo up to 35° of rotation before 1 mm of change in the LT profile occurs. Care must be taken to check other markers of rotation such as by clinical examination during fixation of femoral fractures and not rely solely on the LT profile.

CLINICAL RELEVANCE

In the largest study of its kind, this CT-based study of 56,826 LT profile measurements found that when the proximal femur is externally rotated, the LT profile becomes an unreliable marker of rotation, which can lead to excessive internal rotation of the distal fracture fragment. The LT profile should be used with caution, and confirmation of rotation by other means is recommended.

Evaluation of Intraoperative Fluoroscopic Techniques to Estimate Femoral Rotation: A Cadaveric Study

OBJECTIVES

To compare three fluoroscopic methods for determining femoral rotation.

METHODS

Native femoral version was measured by computed tomography in 20 intact femurs from 10 cadaveric specimens. Two Steinmann pins were placed into each left femur above and below a planned transverse osteotomy which was completed through the diaphysis. Four surgeons utilized the true lateral (TL), neck-horizontal angle (NH), and lesser trochanter profile (LTP) techniques to correct the injured femur's rotation using the intact right femur as reference, yielding 120 measurements. Accuracy was assessed by comparing the angle subtended by the two Steinmann pins before and after manipulation and comparing against version measurements of the right femur.

RESULTS

Absolute mean rotational error in the fractured femur compared to its uninjured state was 6.0° (95% CI, 4.6-7.5), 6.6° (95% CI, 5.0-8.2), and 8.5° (95% CI, 6.5-10.6) for the TL, NH, and LTP techniques, respectively, without significant difference between techniques ( p = 0.100). Compared to the right femur, absolute mean rotational error was 6.6° (95% CI, 1.0-12.2), 6.4° (95% CI, 0.1-12.6), and 8.9° (95% CI, 0.8-17.0) for the TL, NH, and LTP techniques, respectively, without significant difference ( p = 0.180). Significantly more femurs were malrotated by >15° using the LTP method compared to the TL and NH methods (20.0% vs 2.5% and 5.0%, p = 0.030). Absolute mean error in estimating femoral rotation of the intact femur using the TL and NH methods compared to CT was 6.6° (95% confidence interval [CI], 5.1-8.2) and 4.4° (95% CI, 3.4-5.4), respectively, with significant difference between the two methods ( p = 0.020).

CONCLUSIONS

The true lateral (TL), neck-horizontal angle (NH), and the lesser trochanter profile (LTP) techniques performed similarly in correcting rotation of the fractured femur, but significantly more femurs were malrotated by >15° using the LTP technique. This supports preferential use of the TL or NH methods for determining femoral version intraoperatively.

[Methods of Measuring Limb Malrotation Following Femoral Osteosynthesis]

Significant malrotation of the femur after osteosynthesis is a serious complication of treatment and has a number of consequences for the patients and causes deterioration of their quality of life. Therefore, it is necessary to be familiar with intraoperative techniques to control the correct rotation, mostly clinical and radiological, which give us the possibility to minimize rotational errors. In the postoperative period, with even a slight suspicion of malrotation, it is necessary to proceed to its exact verification and, in indicated cases, to perform necessary correction. We recommend one of the CT techniques as a very reliable method, however in younger patients we prefer to use MRI. Early diagnosis of the rotational error and especially its size is essential from the point of view of potential reconstructive surgery, which is then chosen also with regard to the location of the original lesion. Key words: femoral osteosynthesis, limb malrotation, methods of measuring.

Measurement of Lag-Screw Anteversion With an iPhone During Trochanteric Fracture Surgery

Introduction  A useful way to easily evaluate femoral rotation during surgery for trochanteric fractures is not known. Hence, this pilot study aimed to develop an intraoperative indicator to evaluate anteversion in femoral trochanteric fractures. Material and methods Prospectively, from June 2021 to January 2022, all patients with femoral trochanteric fractures (Orthopaedic Trauma Association classification: 31A1-3) treated using a cephalo-medullary nail with a lag-screw neck-shaft angle of 125° were included in this study. During surgery, lag-screw anteversion (LS-AV) was measured using the goniometer application in an iPhone with the fractured femur table-top-plane level with the traction table floor. Accuracy was analyzed by comparing axial-projected lag-screw anteversion (AxP-LS-AV) and three-dimensional computed tomography lag-screw anteversion (3DCT-LS-AV) measurements after surgery. Results Fifty patients (14 males and 36 females) were included in the study. The mean age was 87 (range; 69-98) years; the Orthopaedic Trauma Association classifications were A1 (28 patients), A2 (18 patients), and A3 (4 patients). The mean LS-AV was 10.7° ± 6.9°, the mean AxP-LS-AV was 12.8° ± 8.3°, and the mean 3DCT-LS-AV was 13.1° ± 8.6°. The median difference between AxP-LS-AV and 3DCT-LS-AV was 3.0° (range: 0°-12°), and 40 (80%) patients had differences of ≤5° (Bland-Altman plot: inside of limit of agreement = 86%, paired t-test p = 0.7, Pearson correlation coefficient r = 0.817, p <0.001). Conclusion Femur malrotation is defined as a deformity of >15° relative to the normal contralateral limb. Intraoperative LS-AV iPhone measurement on table-top-plane standard had sufficient accuracy as an indicator of anteversion in femoral trochanteric fractures.