BACKGROUND: The malimplantation of the total knee arthroplasty (TKA) components is one of the main reasons for revision surgery. For determining the correct intraoperative femoral rotation several anatomic rotational axes were described in order to achieve a parallel, balanced flexion gap. In this cadaveric study prevalent used rotational femoral axes and a navigated functional rotational axis were compared to the flexion-extension axis defined as the gold standard in rotation for femoral TKA component rotation.
METHODS: Thirteen body donors with knee osteoarthritis (mean age: 78.85 ± 6.09; eight females and five males) were examined. Rotational computer tomography was performed on their lower extremities pre- and postoperatively. Knee joint arthroplasties were implanted and CT diagnostics were used to compare the preoperatively determined flexion-extension axis (FEA). The FEA is the axis determined by our surgical technique and serves as an internal reference. It was compared to other axes such as (i) the anatomical transepicondylar axis (aTEA), (ii) the surgical transepicondylar axis (sTEA), (iii) the posterior condylar axis (PCA) and (iv) the functional rotation axis (fRA).
RESULTS: Examination of 26 knee joint arthroplasties revealed a significant angular deviation (p*** < 0.0001) for all axes when the individual axes and FEA were compared. aTEA show mean angular deviation of 5.2° (± 4.5), sTEA was 2.7° (± 2.2), PCA 2.9° (± 2.3) and the deviation of fRA was 4.3° (± 2.7). A tendency towards external rotation was observed for the relative and maximum axis deviations of the aTEA to the FEA, for the sTEA and the fRA. However, the rotation of the posterior condylar axis was towards inwards.
CONCLUSIONS: All axes showed a significant angular deviation from the FEA. We conclude that the presented technique achieves comparable results in terms of FEA reconstruction when compared with the use of the known surrogate axes, with certain deviations in terms of outliers in the internal or external rotation.

OBJECTIVE:  The goal of the study is to diagnose and accurately correct malrotation of femur fractures after intramedullary (IM) nailing.
METHODS: An institutional review board (IRB) approved prospective study that was performed at a U.S. level 1 trauma center. After IM nailing of comminuted femur fractures, a computed tomography (CT) scanogram was routinely performed to detect the difference in the postoperative femoral version. Patients with malalignment greater than 15 degrees compared to the contralateral side were informed about the discrepancy and offered to have it acutely corrected. A four-pin technique was used: two Schanz pins were used for measuring angles and two different pins were used to turn and correct the malalignment. The pin in the distal fragment is placed directly under the nail to prevent shortening in comminuted fractures. The nail was unlocked either proximally for retrograde nails or distally for antegrade nails. The Bonesetter Angle application was used as a digital protractor to intraoperatively measure the two reference pins and correct the malrotation. Alternate holes were used for relocking the nail. All patients received a CT scanogram after correction.
RESULTS:  19/128 patients with comminuted femoral fractures over five years with malrotations between 18 and 47 degrees were included in the study with an average malrotation of 24.7 + 8 degrees. All patients were corrected to an average of 4.0 +/- 2.1 degrees difference, as compared to the contralateral side (range 0-8). No patients required further surgeries to correct malrotation.
CONCLUSIONS:  Comminuted fractures with malrotation >15 degrees after femoral nailing have an incidence of 15% at our institution. This technique provides an efficient and accurate correction method with the use of an intraoperative digital protractor, avoiding the need for revision IM nailing or osteotomies.

The standard treatment of femoral shaft fractures is intramedullary nailing. One of the most frequent complications is femoral malrotation. Our study sought to: 1) use EOS imaging to determine the amount of rotational malalignment after intramedullary nailing that has an impact on 6-month functional results; 2) determine the incidence of femoral malrotation based on EOS imaging; 3) determine the risk factors for postoperative femoral malrotation that impacts the 6-month functional results. The hypothesis was that EOS imaging can be used to determine the amount of femoral malrotation that has a functional impact in patients treated by percutaneous femoral intramedullary nailing.
We performed a prospective, single-center study between September 2017 and February 2020. Patients who had suffered a femoral shaft fracture treated with antegrade intramedullary nailing were included in this study. Femoral anteversion was measured at 6 months with an EOS stereoradiographic imaging system. Patients were assessed at 6 months with the WOMAC, Oxford, Harris and MDP functional scores. The SF-12 quality of life score was also determined.
Thirty patients were evaluated at 6 months postoperatively, 15 women (50%) and 15 men (50%) who were 47 years old on average [16; 94]. The average anteversion was 19.9°C [-23°; 75°]. The functional scores (Oxford and Harris) were altered when there was 14° or more difference in femoral torsion between the operated side and the healthy side with a sensitivity of 0.88 and a specificity of 0.77. The risk factors for femoral malrotation were age under 35 years (p=0.01), urgent surgical management (p=0.008), location in middle third of femoral shaft (p=0.05), and short spiral fracture (p=0.02).
The use of EOS imaging allowed us to demonstrate that functional hip outcomes are altered at 6 months postoperatively when greater than 14° femoral malrotation is present compared to the contralateral side after femoral intramedullary nailing. The risk factors that contributed to intraoperative rotational malalignment were age less than 35 years, urgent surgical management, mid-shaft femoral fracture and short spiroid fractures.
II.

Femoral shaft fractures are one of the most common injuries in trauma patients. The gold standard treatment consists of closed reduction and intramedullary nailing, providing a high fracture healing rate and allowing early mobilization. However, rotational malalignment is a well-known complication following this procedure, and excessive femoral anteversion or femoral retroversion can trigger functional complaints. In order to achieve the ideal degree of femoral rotation, a 3D planning and printing cutting guides procedure was developed to correct femoral malrotation. A patient series with malalignment after a femoral diaphyseal fracture was operated on with the customized guides and evaluated in this study. Computed tomography scans were performed to accurately determine the number of degrees of malrotation, allowing the design of specific and personalized surgical guides to correct these accurately. Once designed, they were produced by 3D printing. After surgery with the customized guides to correct femoral malrotation, all patients presented a normalized anteversion angle of the femur (average -10.3°, range from -5° to -15°), according to their contralateral limb. These data suggest that the use of customized cutting guides for femoral osteotomy is a safe and reproducible surgical technique that offers precise results when correcting femoral malrotation.

OBJECTIVE: Proper rotational alignment of the femoral component is critical for a successful total knee arthroplasty (TKA). The aim of this systematic review was to analyse the available literature to examine the effect of the TKA femoral component malrotation on clinical outcomes and assess a cut-off value for femoral rotation leading to revision surgery.
METHODS: A detailed and systematic search from 1996 to 2019 of the PUBMED, Medline, Cochrane Reviews and Google Scholar databases had been performed using the keyword terms \"total knee arthroplasty OR replacement\" AND \"femoral alignment OR malalignment OR femoral rotation OR malrotation\" AND \"clinical outcome\". We used the methodological index for non-randomized studies (MINORS) to identify scientifically sound articles in a reproducible format.
RESULTS: Eleven articles met inclusion criteria. A total of 896 arthroplasties were included in this review; 409 were unexplained painful TKA patients, while 487 were painless TKA patients. The mean age of patients was 67.5 (± 2.1) years. The mean post-operative follow-up delay was 46.8 (± 32.2) months. The mean of MINORS score was 21 points indicating good methodological quality in the included studies.
CONCLUSIONS: The present review confirms that the malrotation of the femoral component in TKA does not correlate automatically to poor clinical and functional outcome. The clinical relevance of this study was that, to improve accuracy in femoral component rotation, surgeons should consider the anatomical variability of femur in each knee and perform additional measurements pre- and intra-operatively. Taking a more accurate approach will shed light on unanswered questions in unhappy TKA.
METHODS: III.

BACKGROUND: Malrotation of the femur is a frequent complication in the management of a diaphyseal fracture. It is often responsible for pain and adverse functional results. Among these complications, contact stress effects on the patellofemoral joint are recognized as predictive factors of impaired results. The purpose of this study was to analyze the effect of malrotation on stress distribution on the patellofemoral joint, using radiological measurement and three-dimensional finite element models.
METHODS: Functional analysis of the patellofemoral joint was evaluated in eight knee pairs from patients with unilateral femoral fractures and subsequent femoral malrotation. A computed tomography-based protocol allowed patellofemoral joint analysis. A finite element model of the healthy (contralateral) knee was then created from 3D reconstruction at 30° flexion. In a finite element model, incremental rotational malalignment was simulated to observe changes in stress distribution on the patellar surface.
RESULTS: Femoral malrotation was associated with anomalies of patellofemoral joint rotational alignment. Internal rotation resulted in increased stress on the lateral side of the patella, and external rotation increased inferior medial side stress.
CONCLUSIONS: Rotational disorders of the distal femur resulted in increased stress on the patellofemoral joint and alignment changes. Malrotation in internal and external rotation might cause patellofemoral pain syndrome from rotations <10°. Care should be taken especially for internal malrotation in the management of femoral shaft fracture.

In some surgical techniques like femoral derotation osteotomy, accuracy is a key factor that often is not optimal because of the lack of appropriate technology. 3D printing is emerging in many professional areas and its use in the medical field may enhance the results of certain surgeries. This case describes a patient who underwent an intramedullary nail fixation to treat a femoral shaft fracture. After nine months, the patient presented hip pain and \"in toe\" walking caused by a malrotation produced during the surgery. To address the consequent femoral derotation osteotomy, 3D technology was used throughout the whole process. A 3D model of the patient\'s femur was created to conduct a real and accuracy assessment of femoral anteversion. Then, a customized surgical guide was designed and printed to ensure the proper alignment during surgery. Given the success of this surgery, 3D printing can be considered a quick and inexpensive tool to improve surgical results.

BACKGROUND: Rotational malalignment is an important and not always avoidable complication after surgical treatment of femoral shaft fractures. The purpose of this study was to determine the incidence of rotational malalignment in children after surgical treatment of femoral shaft fractures and to identify potential patient- and treatment-related risk factors based on data obtained from CT scans.
METHODS: We conducted a retrospective analysis of all patients aged less than 15 years with femoral shaft fractures admitted to our level 1 trauma centre between January 2004 and July 2014. Patients having obtained postoperative CT scans were included for the determination of rotational malalignment. A difference of greater than 15° in femoral torsion between both legs was considered as clinically relevant. Additionally, demographic data and clinical information such as fracture type, treatment method, fluoroscopy time and operating time were reviewed.
RESULTS: A total of 24 patients were enrolled in this study. Clinically relevant femoral malrotation was identified in 10 patients (41.6%). Surgical revision was performed in 7 patients (29.2%). There was no association between the type of surgical procedure, age and the incidence and/or amount of femoral malrotation.
CONCLUSIONS: The data suggest that relevant femoral malrotation is an evident problem after surgical treatment of femoral shaft fractures in children that requires critical postoperative assessment.
METHODS: Level III, retrospective study.