Introduction. Understanding the implications of decreased femoral torsion on gait and running in children and adolescents might help orthopaedic surgeons to optimize treatment decisions. To date, there is limited evidence regarding the kinematic gait deviations between children with decreased femoral torsion and typically developing children as well as regarding the implications of the same on the adaptation of walking to running. Method. A three dimensional gait analysis study was undertaken to compare gait deviations during running and walking among patients with decreased femoral torsion (n=15) and typically developing children (n=11). Linear mixed models were utilized to establish comparisons within and between the two groups and investigate the relation between clinical examination, spatial parameters and the difference in hip rotation between running and walking. Result. Patients exhibited increased external hip rotation during walking in comparison to controls accompanied by higher peaks for the same as well as for, knee valgus and external foot progression angle. A similar kinematic gait pattern was observed during running with significant differences noted in peak knee valgus. In terms of variations from running to walking, patients internally rotated their initially external rotated hip by 4°, whereas controls maintained the same internal hip rotation. Patients and controls displayed comparable kinematic gait deviations during running compared to walking. The passive hip range of motion, torsions and velocity did not notably influence the variation between mean hip rotation from running to walking. Conclusion. This study underlines the potential of 3D gait kinematics to elucidate the functional implications of decreased FT and hence may contribute to clinical decision making

Introduction. Torsional deformities are increasingly recognized as an additional factor in young patients with hip pain resulting from pincer- and cam-deformities. For example decreased femoral torsion can worsen an anterior Femoroacetabular impingement (FAI) conflict while an increased torsion can be beneficial with the same configuration. It is unknown how often torsional deformities are present in young patients presenting with hip pain that are eligible for joint preserving surgery. We questioned (1) what is the prevalence of a pathological femoral torsion in hips with FAI or hip dysplasia? (2) which hip disorders are associated with an abnormal torsion?. Methods. An IRB-approved retrospective study of 463 consecutive symptomatic FAI patients (538 hips) and a MRI or CT scan on which femoral torsion could be measured was performed (‘study group'). Out of 915 MRI we excluded 377 hips. The study group was divided into 11 groups: Dysplasia (< 22° LCE), retroversion, anteverted hips, overcoverage (LCE angle 36–39°), severe overcoverage (LCE>39°), cam (>50° alpha angle), mixed FAI, varus- (<125° CCD angle), valgus- (>139° CCD), Perthes-hips and hips with no obvious pathology. The ‘control group' of normal hips consisted of 35 patients (35 hips) without radiographic signs of osteoarthritis or hip pain wich was used for a previous study. Femoral antetorsion was measured according to Tönnis et al. as the angle between the axis of the femoral neck and the posterior axis of the femoral condyles. Normal femoral torsion was defined by Tönnis et al. as angles 10–25° while decreased resp. increased torsion was defined as <5° and >25°. Statistical analysis was performed using analysis of variances (ANOVA). Results. (1) Fifty-one percent of the patients of the study group presented with abnormal values for femoral torsion. Torsional deformities (<10° or >25°) were measured in 52% of all 538 hips eligible for joint preserving surgery. (2) Torsional deformities were present in 86% of Perthes hips, in 61 % of dysplastic hips, 52.3 % of hips with overcoverage, in 51% of mixed FAI, in 50% of varus hips, in 45% of valgus hips, in 45% of retroverted hips, in 47% of anteverted hips, in 43% of cam FAI, 35% of hips with severe overcoverage. No torsional deformity was present in the control group. Analysis of Variances (ANOVA) revealed significant differences (p<0.001) of torsion between normal hips (mean 17°) and hips with dysplasia (26°), valgus hips (27°), hips with no obvious pathology (30°) and Perthes hips (32°). Mean femoral torsion was in the normal range in the other groups. Conclusion. More than half of the patients wich are eligible for joint preserving surgery of the hip present with abnormal femoral torsion. In particular dysplastic-, valgus-, Perthes hips and hips with no obvious pathology had a significantly altered femoral torsion compared to normal hips. Femoral antetorsion should be measured in every patient eligible for hip-preserving surgery

Background: Blount’s original paper in 1937 described a case series of 28 patients with “Tibia Vara”. Since then various authors have attempted to describe in more detail the tibial and femoral deformities seen in this disease. It is still a poorly understood condition. This study describes the femoral rotational deformity that can occur in Blount’s disease.

Methods: Over a 2 year period, all patients with Blount’s disease seen in the Orthopaedic department of a regional hospital in South Africa were entered into a database. They underwent a review of their notes, a clinical rotational profile of their lower limbs and a CT scan of the femoral head/neck and distal femur. From this database we performed a cross sectional study. We then compared our results both to previously published controls for hip rotation and anteversion angles and with respect to the rotational profile, to a small cohort of 32 “normal” local children.

Results: A statistically significant increase in femoral anteversion in the affected legs was noted, with on average the femurs in Blount’s disease being 26 degrees more anteverted than previously published controls. A significant decrease in external rotation were also noted.

Conclusions: Our results suggest that the marked intoeing seen in many cases of Blount’s disease may be caused by internal femoral version, in addition to the well recognized internal tibial version. This study highlights the following issues:

A rotational profile should be part of the routine clinical assessment of all Blount’s cases.

Introduction. The current methods for measuring femoral torsion have limitations, including variability and inaccuracies. Existing 3D methods are not reliable for abnormal femoral anteversion measurement. A new 3D method is needed for accurate measurement and planning of proximal femoral osteotomies. Currently available software for viewing and modelling CT data lacks measurement capabilities. The MSK Hip planner aims to address these limitations by combining measurement, planning, and analysis functionalities into one tool. We aim to answer 5 key questions: Is there a difference between 2D measurement methods? Is there a difference between 3D measurement methods? Is there a difference between 2D and 3D measurement methods? Are any of the measurement methods affected by the presence of osteoarthritis or a CAM deformity?. Method. After segmentation was carried out on 42 femoral CT scans using Osirix, 3D bone models were landmarked in the MSK lab hip planning software. Murphy's, Reikeras’, McBryde, and the novel MSK lab method were used to measure femoral anteversion. Result. Murphy's method had the lowest mean femoral neck anteversion (FNA) at 24.98°, while the MSK method had the highest at 28.55°. Bland-Altman plots showed systematic errors between 2D (1.201°) and 3D (1.074°) methods. All methods demonstrated good intra- and inter-user reliability. Significant differences were found between measurement methods and between patient groups. Conclusion. The MSK Hip Planner software proved useful and convenient to measure FNA. Statistically significant differences in FNA were observed between the measurement methods, as well as between patient groups when split by presence of osteoarthritis and cam deformity. Complex joint pathology and altered femoral morphology should be considered by clinicians when deciding which method to use when measuring FNA

With the growing number of individuals with asymptomatic cam-type deformities, elevated alpha angles alone do not always explain clinical signs of femoroacetabular impingement (FAI). Differences in additional anatomical parameters may affect hip joint mechanics, altering the pathomechanical process resulting in symptomatic FAI. The purpose was to examine the association between anatomical hip joint parameters and kinematics and kinetics variables, during level walking. Fifty participants (m = 46, f = 4; age = 34 ± 7 years; BMI = 26 ± 4 kg/m²) underwent CT imaging and were diagnosed as either: symptomatic (15), if they showed a cam deformity and clinical signs; asymptomatic (19), if they showed a cam deformity, but no clinical signs; or control (16), if they showed no cam deformity and no clinical signs. Each participant's CT data was measured for: axial and radial alpha angles, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version, and centre-edge angle. Participants performed level walking trials, which were recorded using a ten-camera motion capture system (Vicon MX-13, Oxford, UK) and two force plates (Bertec FP4060–08, Columbus, OH, USA). Peak sagittal and frontal hip joint angles, range of motion, and moments were calculated using a custom programming script (MATLAB R2015b, Natick, MA, USA). A one-way, between groups ANOVA examined differences among kinematics and kinetics variables (α = 0.05), using statistics software (IBM SPSS v.23, Armonk, NY, USA); while a stepwise multiple regression analysis examined associations between anatomical parameters and kinematics and kinetics variables. No significant differences in kinematics were observed between groups. The symptomatic group demonstrated lower peak hip abduction moments (0.12 ± 0.08 Nm/kg) than the control group (0.22 ± 0.10 Nm/kg, p = 0.01). Sagittal hip range of motion showed a moderate, negative correlation with radial alpha angle (r = −0.33, p = 0.02), while peak hip abduction moment correlated with femoral neck-shaft angle (r = 0.36, p = 0.009) and negatively with femoral torsion (r = −0.36, p = 0.009). With peak hip abduction moment in the stepwise regression analysis, femoral torsion accounted for a variance of 13.3% (F(1, 48) = 7.38; p = 0.009), while together with femoral neck-shaft angle accounted for a total variance of 20.4% (R² change = 0.07, F(2, 47) = 6.01; p = 0.047). Although elevated radial alpha angles may have limited sagittal range of motion, the cam deformity parameters did not affect joint moments. Femoral neck-shaft angle and femoral torsion were significantly associated with peak hip abduction moment, suggesting that the insertion location of the abductor affects muscle's length and its resultant force vector. A varus neck angle, combined with severe femoral torsion, may ultimately influence muscle moment arms and hip mechanics in individuals with cam FAI

Posterior extraarticular ischiofemoral hip impingement can be caused by high femoral torsion and is typically located between the ischium and the lesser trochanter. We asked if patients undergoing derotational femoral osteotomies for posterior FAI have (1) decreased hip pain and improved function and evaluated (2) subsequent surgeries and complications?. Thirty-three hips undergoing derotational femoral osteotomies between 2005 and 2016 were evaluated retrospectively. Of them 15 hips underwent derotational femoral osteotomies and 18 hips underwent derotational femoral osteotomies combined with varisation (neck-shaft angle >139°). Indication for derotational osteotomies was a positive posterior impingement test in extension and external rotation, high femoral torsion (48° ± 9) on CT scans and limited external rotation. Offset improvement was performed to avoid intraarticular impingement in hips with a cam-type FAI. All patients were female and mean followup was 3 ± 2 (1 – 11) years. At latest followup the positive posterior and anterior impingement test decreased from preoperatively 100% to 5% (p< 0.001) and from preoperatively 85% to 30% (p< 0.001). The mean Merle d'Aubigné Postel score increased from 14 ± 1 (11 – 16) to 16 ± 1 (13 – 17) at latest followup (p< 0.001). At followup 32/33 hips had been preserved and one hip had been converted to a total hip arthroplasty (THA). In two hips (6%) revision osteosynthesis was performed for delayed healing of the femoral osteotomy. Derotational femoral osteotomies for the treatment of posterior extraarticular ischiofemoral impingement caused by high femoral torsion result in decreased hip pain and improved function at midterm followup but had 6% delayed healing rate requiring revision surgery

Arthroscopic hip procedures have increased dramatically over the last decade as equipment and techniques have improved. Patients who require hip arthroscopy for femoroacetabular impingement on occasion require surgery on the contralateral hip. Previous studies have found that younger age of presentation and lower Charlson comorbidity index have higher risk for requiring surgery on the contralateral hip but have not found correlation to anatomic variables. The purpose of this study is to evaluate the factors that predispose a patient to requiring subsequent hip arthroscopy on the contralateral hip. This is an IRB-approved, single surgeon retrospective cohort study from an academic, tertiary referral centre. A chart review was conducted on 310 primary hip arthroscopy procedures from 2009-2020. We identified 62 cases that went on to have a hip arthroscopy on the contralateral side. The bilateral hip arthroscopy cohort was compared to unilateral cohort for sex, age, BMI, pre-op alpha angle and centre edge angle measured on AP pelvis XRay, femoral torsion, traction time, skin to skin time, Tonnis grade, intra-op labral or chondral defect. A p-value <0.05 was deemed significant. Of the 62 patients that required contralateral hip arthroscopy, the average age was 32.7 compared with 37.8 in the unilateral cohort (p = 0.01) and BMI was lower in the bilateral cohort (26.2) compared to the unilateral cohort (27.6) (p=0.04). The average alpha angle was 76.3. 0. in the bilateral compared to 66. 0. in the unilateral cohort (p = 0.01). Skin to skin time was longer in cases in which a contralateral surgery was performed (106.3 mins vs 86.4 mins) (p=0.01). Interestingly, 50 male patients required contralateral hip arthroscopy compared to 12 female patients (p=0.01). No other variables were statistically significant. In conclusion, this study does re-enforce existing literature by stating that younger patients are more likely to require contralateral hip arthroscopy. This may be due to the fact that these patients require increased range of motion from the hip joint to perform activities such as sports where as older patients may not need the same amount of range of motion to perform their activities. Significantly higher alpha angles were noted in patients requiring contralateral hip arthroscopy, which has not been shown in previous literature. This helps to explain that larger CAM deformities will likely require contralateral hip arthroscopy because these patients likely impinge more during simple activities of daily living. Contralateral hip arthroscopy is also more common in male patients who typically have a larger CAM deformity. In summary, this study will help to risk stratify patients who will likely require contralateral hip arthroscopy and should be a discussion point during pre-operative counseling. That offering early subsequent or simultaneous hip arthroscopy in young male patients with large CAMs should be offered when symptoms are mild

The coronal plane lower limb alignment plays an important role in the occurrence and progression in knee osteoarthritis. There have been reports of the valgus knee in patients with unilateral developmental hip dislocation (UDHD) with the relatively small sample size. Besides, few studies have analyzed the lower limb alignment of the contralateral side. The purpose of our study was to identify the coronal plane alignment of both the ipsilateral and the contralateral lower limb in patients with UDHD and find out the difference between patients with Hartofilakidis type II and III. The radiographic data of all UDHD patients who met the inclusion criteria from March 2011 to February 2017 were retrospectively reviewed, including the hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), anatomical lateral distal femoral angle (aLDFA), mechanical proximal tibial angle (MPTA) and the lateral distal tibial angle (LDTA). Besides, the femoral torsion angle was measured on the images of CT scan. The average HKA was 3.42°(range: −4.3–12.8°) on the affected side, and −2.11°(range: −11.4–5.4°) on the contralateral side (P?0.0001). The valgus lower limb alignment on ipsilateral side was most frequently seen in both Hartofilakidis type II (20cases, 51.3%) and type III groups (25cases, 67.6%), whereas for the contralateral side, the neutral alignment in type II group (27 cases, 69.2%) and varus alignment in type III group (19 cases, 51.4%) were most commonly observed. Both the mLDFA (P?0.001) and aLDFA (P?0.001) of ipsilateral side were significantly smaller than those of contralateral side. The average femoral torsion angle was 37.9°(range: 10.4–64.4°) on the affected side, and 27.1°(range: 9.7–45.5°) on the contralateral side (P?0.001). In conclusion, UDHD patients may present with lower limb malalignment on both sides. The valgus lower limb alignment is the most common deformity on ipsilateral side, which is caused by increased femoral torsion angle as well as the decreased aLDFA. The patients with Hartofilakidis type III UDHD may be more prone to present varus alignment deformity than those with Hartofilakidis type II on the contralateral side. The lower limb malalignment and deformity of ipsilateral distal femur should be considered during any surgery involving hip, knee or femur

Purpose of the study: The purpose of this study was to confirm long-term changes in frontal alignment after wedge osteotomy(even for with an «ideal» postoperative wedge angle of 3–6°), that the frontal alignment is correlated with functional degradation and also with femorotibial skeletal torsion. Material and methods: A non-consecutive retrospective series of 70 patients aged 57.5 on average at surgery for medial open-wedge tibial osteotomy were reviewed at 10–25 years. Goniometry measurements were obtained in the upright position after healing. Tibial and femoral torsion values were measured on the CT scan. Functional outcome at last follow-up was noted good, fair or poor. Results: Postoperatively 80% percent of the knees presented frontal realignment within the 3–6° range. At last follow-up frontal alignment had changed on average 10° for 40% of knees. The change in frontal alignment resulted from a deterioration of the medial or lateral joint space and in 80% was associated with poor functional outcome. Knees which preserved valgus of 3–6° at last follow-up had statistically better results than the rest of the series. There was a correlation between valgus frontal misalignment and femoral torsion greater than 14° (anteversion) and between varus frontal misalignment and femoral torsion less than 14°. There thus appeared to be a linear correlation between postoperative changes in the correction and femoral torsion. Conclusion: Good functional outcome of open wedge tibial osteotomy is correlated with stability of the axial correlation over time. Achieving postoperative valgus of 3–6° does not appear to be sufficient for stable axial correction. To achieve long-term preservation of the axial correction, it would be preferable to modulate the postoperative correction according to the degree of femoral torsion

Introduction and Objective. The geometry of the proximal tibia and distal femur is intimately linked with the biomechanics of the knee and it is to be considered in total knee arthroplasty (TKA) component positioning. The aim of the present study was to evaluate the proximal tibial torsion in relation to the flexion-extension axis of the knee in healthy and pathological cohort affected by knee osteoarthritis (OA). Materials and Methods. We retrospectively analyzed computed tomography scans of OA knee of 59 patients prior to TKA and non-arthritic knee of 39 patients as control. Posterior condylar angle (PCA), femoral tibial torsion (TEAs-PTC and TEAs-PTT), proximal tibial torsion (PTC-PTT and PCAx-PTC) and distance between tibial tuberosity and the trochlear groove (TT-TG) were measured. Results. No differences were found for gender, age, TG-TT and PCAn angles. Statistically significant differences were found for all the other angles considered. Significant relation was found between Tibial Torsion and TEA-PTT angles, between PCAx-PTC and TEA-PTC, between TEA-PTT and TEA-PTC and between PCAx-PTC and TEA-PTT. All measures, except TG-TT and PCAn angles, showed high validity (AUC > 75%) in detecting OA, with TEA-PTT displaying the highest validity with an AUC of 94.38%. Conclusions. This is the first study to find significant differences in terms of proximal tibia geometry and anatomy between non arthritic and OA knees. It is conceivable that such anatomy could be implicated in the development of OA. Based on our data, the TEAs is a valid reference for correct positioning of tibial component in TKA. Indeed, setting the tibial component parallel to TEAs makes the prosthetic knee more similar to the native non-arthritic knee

In THA navigation systems mostly the anterior pelvic plane (APP) is used as reference for cup orientation. For the femoral torsion the sagittal plane of the leg in 90° knee flexion is used as reference. The common procedure is associated with a pointer based palpation of anatomical landmarks. But sometimes it shows difficulties especially in obese patients. The purpose of the current prospective study was to evaluate the THA navigation based on palpation of the APP and the femoral sagittal plane using a novel intra-operative ultrasound device in comparison to standard palpation technique. Methods: In 2006 the data of 50 patients with navigated THA were analyzed. An image free computer-assisted navigation system (OrthoPilot, B. Braun Aesculap, Germany) was used together with an integrated ultrasound device (probe: 80mm, 5–8 MHz, Telemed, Latvia). First, the registration of bony landmarks, i.e. anterior iliac spines and symphysis for APP as well as patella and tibial pylon for the femoral sagittal axis was performed using the conventional pointer method (PO). Then registration was repeated using the ultrasound device (US). The landmarks of the APP and the dorsal condylar line to define the femoral torsion alignment were recorded. The intra-operative cup orientation and the resulting range of motion was monitored. After cup placement in the “safe zone” described by Lewinnek the femoral stem was rasped monitoring the predicted final ROM, leg length and offset. The navigation software provides simultaneously data for for both, pointer and ultrasound palpation. Cup anteversion, inclination, the antetorsion angle of the rasp as well as the predicted amount of impingement free internal (IR) and external rotation (ER) of the leg are shown. At the end of operation ROM was checked clinically. Plain standardized post-operative X-rays were evaluated for inclination and anteversion angles according to Pradhan. Results: The calculated mean difference between US registration and PO palpation was 2,2° (range -1,7 – 5.9°) for the cup inclination and 8,7° (range 1,5° – 16°) for anteversion. The impingement free total ROM of the femur as predicted by the Orthopilot, i.e. 109° for PO and 103° for US registration matched well with the clinical data. The clinical findings confirmed the US registration based ratio of mean external (ER 62°) to internal rotation (IR 41°). However, the predicted mean IR as calculated for PO palpation, i.e. 31°, was reduced by a mean of 9° in favor of 13° of more ER (76°). Conclusion: The results show a higher coincidence of US based registration with the clinical findings. The difference is due to a registration at the bone surface with the US method, while PO palpation cannot overcome a undefined thickness of soft tissue layer, especially in front of the symphysis in obese patients

Aims

The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors?

Introduction. The aim of the present study was to evaluate the discrepancies of rotational profiles of whole limb between operated and non-operated limb following unilateral total knee arthroplasty. Materials and Methods. We conducted an analysis the CT data from 32 patients undergoing primary unilateral total knee arthroplasty using measured resection technique, which femoral component was always implanted with external rotation to posterocondylar axis from July 2009 to April 2013. Using these CT scan, rotational profiles of total limb such as femoral torsion angle (femoral neck anteversion angle; FTA), tibial torsion angle (TTA), knee joint rotation angle (KJRA) and total limb rotation (TLR) were measured. Results. There were significant discrepancies of FTA and KJRA between operated and non-operated limb following unilateral total knee arthroplasty. The mean difference of operated and non-operated side for FTA and KJRA were −6.51 ± 11.88º (p=0.0041) and −6.83 ± 5.04º (p < 0.001) respectively. However, there were no significant discrepancies of TLR, TTA. TTA and TLR showed strong correlation (r= 0.7309). Conclusion. FTA showed significant side to side discrepancy, TTA and TLR showed no significant discrepancy between operated- and non-operated limbs in patients undergone unilateral TKA. These results are due to the compensation effect of KJRA. However, excessive external rotation of femoral component beyond the compensation effect of prosthetic knee joint can lead to total limb rotational discrepancy in patient undergoing unilateral total knee arthroplasty

Background. A careful consideration of change of the rotational profiles of total limb after unilateral total knee arthroplasty is necessary. The aim of the present study was to evaluate the discrepancies of rotational profiles of total limb between operated and non-operated limb following unilateral total knee arthroplasty. Methods. We conducted a retrospective analysis the CT data from 32 patients undergoing primary unilateral total knee arthroplasty using measured resection technique, which femur implant was applied at an external rotation of 3° relative to the posterior condylar axis from July 2009 to April 2013 in our hospital. Using these CT studies, rotational profiles of total limb such as femoral torsion angle (femoral neck anteversion angle; FTA), tibial torsion angle (TTA), neck-malleolar angle (NMA), knee joint rotation angle (rotational mismatch; KJRA) and total limb rotation (TLR) were measured. Results. There were significant discrepancies of FTA and KJRA between operated and non-operated limb following unilateral total knee arthroplasty. The mean difference of operated and non-operated side for FTA and KJRA were −6.5 ± 11.9° (p=0.004) and −6.8 ± 5.0° (p < 0.001) respectively. However, there were no significant discrepancies of TLR, TTA and NMA. Conclusion. With comparison with non-operated side, although FTA is significantly decreased in operated limb than non-operated limb following total knee arthroplasty, there were no significant discrepancies of NMA and TLR, because of the compensatory effect of KJRA. However, excessive external rotation of femur implant can affect adversely on rotational profiles of total limb. Further long term studies will be required to evaluate the change of the rotational profiles following unilateral total knee arthroplasty

Introduction. Radiographs and computed tomography (CT) images are used for the preoperative planning in total knee arthroplasty (TKA), however, these two-dimensional (2D) measurements are affected easily by limb position and scanning direction relative to three-dimensional (3D) bone model analyses. The purpose of our study was to compare these measurements to evaluate the factors affecting the difference. Patients and Methods. A total of 75 osteoarthritis knees before primary TKA were assessed. The full-length weight-bearing anteroposterior radiograph and CT slices were used for the 2D measurement. Three-dimensional measurement used 3D bone model reconstructed from the CT data and the coordinate system as the previous reports (Figure 1). We measured FVA (femoral valgus angle), CRA (the angle between the posterior condylar line <PC-L> and the clinical epicondylar axis <CEA>), and SRA (the angle between the PC-L and the surgical epicondylar axis <SEA>). Intra- and inter-observer reliabilities were assessed by intraclass correlation coefficients (ICC), and the differences between the 2D and the 3D measurements (Differences) were evaluated. In addition, we evaluated whether preoperative factors (preoperative extension angle, HKA, BMI and CT scanning direction) affected the differences between the 3D and the 2D measurements. Computer simulation was used to examine the influences of CT scanning direction. Results. The ICC and the mean values with 2D and 3D measurements were shown in Table 1. The mean Differences were 0.2 ± 1.2° in FVA, 0.7 ± 2.1° in CRA and 0.7 ± 1.8° in SRA. Nine percentage in CRA and 13% in SRA had over 3 degrees of the Differences. There were no significant correlations between these factors and the Difference, however, the 3D simulation showed a significant difference of CRA between the scanning direction in varus/valgus and the neutral condition (varus: p<0.001, valgus: p<0.001) (Figure 2). Discussion. From our study, the 3D measurements were highly reliable. In the 2D measurements, the rotational measurements showed less interobserver reliability because of the difficulty of picking the same CT plane and the same position of femoral bony landmarks between observers. The mean Differences were small, however, the range was large and almost10% of our cases were over 3 degrees which can induce the malalignment of the component in spite of the precise bone cutting. Particularly, smaller values of the CRA and SRA with the 2D measurement have a risk of internal-rotated position of the femoral component. Preoperative osteoarthritis knees have flexion contractures, valgus, and femoral torsion. The 3D measurements are useful to avoid the different evaluation from the CT scanning situation

Aims

Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data.

We report a case of a 20-year-old microcephalic patient who suffered from symptomatic patellar dislocation since his early days. His patella was laterally dislocated from full extension to 40° of flexion and would remain subluxated thereafter. His CT-scan revealed excessive ipsilateral femoral neck anteversion (45°) that resulted in substantial internal femoral torsion and subsequently led to patella dislocation. He was treated in one stage with a stepwise procedure, that involved arthroscopic assessment of patellar tracking followed by derotational femoral shaft osteotomy. Tracking was reassessed arthroscopically and although improved was still suboptimal. Therefore an arthroscopic lateral release and an Elmslie-Trillat tibial tubercle transfer were undertaken. This led to very satisfactory patellar tracking. One year postoperatively he had significant functional improvement, no further episodes of patellar dislocation and a ROM of 0–110°. His Lysholm score improved from 45 to 88, his Tegner activity scale from 2 to 4 and his Knee Outcome Score from 38/80 to 70/80. This complex case highlights excessive femoral neck anteversion as a causative factor for patella dislocation. A combination of proximal and distal bony realignment procedures is proposed and the role of arthroscopy is emphasised

Purpose: Femoral torsion is traditionally treated by a proximal osteotomy. At this level, a significant exposure is required. Furthermore, internal fixation is typically removed by additional surgery at twelve months. We propose to demonstrate the efficacy of the AO external fixator to maintain osteotomies in the distal femur for torsional correction. Method: Between September 1994 and April 2001, supracondylar osteotomies were performed on 38 femora in 21 children with torsional and angular deformities. The average age at presentation was 10 years. Twenty-three femora had excessive anteversion and 15, retroversion. The technique required the lateral placement of three 4.0 mm end-threaded Schanz pins parallel to the distal growth plate. Three similar pins were inserted more proximally in line with the femoral shaft. A transverse osteotomy was performed through a limited lateral approach. After correction of the deformities, each pin was linked to all others by clamps and carbon fiber rods. Results: Lower extremity alignment was restored in all patients. Genu valgum was addressed in eighteen osteotomies. Five extension osteotomies were performed for fixed knee flexion deformities. The external fixators were removed at an average of ten weeks. One child had a superficial pin tract infection requiring intravenous antibiotics. All osteotomies united without complications. No postoperative femur fractures occurred. Conclusion: Osteotomy at the distal femur has the advantage of correcting both torsional and angular deformities. The exposure required is limited. The AO external fixator provides precise control of the osteotomy and allows for subsequent adjustability. This method effectively controls supracondylar osteotomies and avoids a second procedure for hardware removal

Purpose of the study: Recent studies have demonstrated that navigation systems provide highly accurate cuts for orthogonal alignment of the lower limb. The accuracy has not to our knowledge been assessed for rotation. Rotation of the femoral piece, which results from a strategy independent of the bone cut, is designed to «correct» for epiphyseal torsion of the distal femur and thus obtain a biepicondylar axis parallel to the «surgical» posterior bicondylar line described by Berger (line drawn between the medial sulcus and the lateral epicondyle), i.e. forming un angle of 2° with the anatomic biepicondylar line described by Yoshioka (line from the medial to lateral condyles). The purpose of this study was to access the precision of navigation rotation. Material and methods: This prospective consecutive study included 40 osteoarthritic knees undergoing total knee arthroplasty (TKA). The anatomic angle of distal femoral torsion (Yoshioka angle: angle formed by the posterior bicondylar line and the biepicondylar line) was measured on the pre- and post(3 months)-operative scans. Navigation (Navitrack, Zimmer) used the rotation given by the preoperative scan to guide the femoral cut with the objective of achieving a residual Yoshioka angle of 2°, i.e. parallel to Berger’s surgical biepicondylar line. The postoperative HKA measured on the pangonogram in the standing position was 179.6±2° with 85% of patients between −2° and +2°, confirming the reliability of the navigation system. Results: The mean preoperative epiphyseal rotation of the distal femur was 6.4±1.8°. The mean postoperative measurement was 1.1±2.4°. Eighty percent of patients were within ±2° of the objective. Discussion: We demonstrated in previous work that navigation-based rotation using intraoperative data is satisfactory as long as the degree of rotation is based on the preoperative scan (and thus takes into account the wide rang of distal femur torsion). Navigation-based rotation is a progress compared with standardized rotation. The few errors observed were related to insufficient identification of the posterior bicondylar line during navigation or to difficulties in interpreting the postoperative scan

Purpose: The position of the femoral implant in external rotation remains a controversial issue. It can be determined using bone landmarks (Whiteside line, parallel to the biepicondylar axis, 3° external rotation from the posterior condylar plane). For the last seven years, we have related femoral rotation to the orientation of the tibial cut in order to ensure good femorotibial stability in flexion using specific instruments (Cores®). This prospective study was conducted to examine the position of the femoral implant determined with this method and to measure the position from bone landmarks. Material and methods: Twenty consecutive patients were included in this study. Bilateral computed tomographic measurements were made before and after surgery. Joining 8mm/8 slices were obtained for the femoral necks and 5mm/3 slices for the knees. The angle of femoral torsion was defined in two ways: the first by the angle formed between the axis of the femoral neck (on two superimposed slices) and the tangent to the most posterior part of the femoral condyles; the second by the angle formed between the epidondylar line and the posterior condylar line. Results: The preoperative scans demonstrated that the angle between the biepicondylar line and the posterior condylar line was 5.8±1.5°. Using Cores®, led to an external rotation of the femoral implant to 2.7±0.6°. The postoperative scans demonstrated that the angle between the biepicondylar line and the posterior condylar prosthetic play was a mean 3.3°. The measurements using the femoral neck were less precise, with, in one case, an external rotation of 5°. The patella was well balanced postoperatively (irrespective of the external rotation position of the femoral implant). Discussion: The angle of about 6° between the biepicondylar line and the posterior plane of the condyles has also been reported by others (Beaufils, Matsuda). To obtain a rectangular space in flexion, the posterior condyle cuts are more important medially than laterally. We found a correlation between the correction provided by the specific instrument set and the difference in the posterior condyle cuts, demonstrating the intraoperative precision of Cores®. It is difficult to orient the femoral piece parallel to the biepicondylar axis. This study demonstrates that there always remains 2 to 3° of inclination of the biepi-condylar axis from the posterior condylar plane. Conclusion: The positioning the femoral implant parallel to the biepicondylar line leads to inducing an important external rotation. While using 3° rotation systematically would reduce the risk of internal malrotation, we feel it better to adapt the rotation to each individual knee depending on the anatomic presentation. Cores® enables positioning the femoral implant in external rotation as a function of the ligament balance obtained in flexion after peripheral tension is applied. This enables avoiding medial femorotibial laxity in flexion