Sagittal Spinopelvic Translation Is Combined With Pelvic Tilt During the Standing to Sitting Position: Pelvic Incidence Is a Key Factor in Patients Who Underwent THA.

BACKGROUND: Sagittal spinopelvic translation (SSPT) is the horizontal distance from the hip center to the C7 plumb line (C7PL). SSPT is an important variable showing the overall patient balance in different functional positions which could affect the rate of hip instability. This study investigates the SSPT modification in patients who underwent total hip arthroplasty (THA). METHODS: A total of 120 patients were assessed preoperatively and postoperatively on standing and sitting acquisitions (primary unilateral THA without complication). SSPT is zero when the C7PL goes through the center of the femoral heads and positive when the C7PL is posterior to the hips' center (negative if anterior). Three subgroups were defined based on the pelvic incidence (PI): low PI <45°, 45°< normal PI <65°, or high PI >65°. RESULTS: The overall mean preoperative SSPT change from standing to sitting was 2.2 cm ([-7.2 to 17.4]) (P < .05). The overall mean postoperative SSPT change from standing to sitting was 1.2 cm ([-14.2 to 22.4]) (P < .05). In low- and normal-PI groups, standing to sitting SSPT and preoperative to postoperative changes in standing SSPT were increased significantly after surgery with the C7PL behind the hips' center (P < .05). In the high-PI group, standing to sitting SSPT was increased postoperatively (P = .034) (no significant changes from preoperative to postoperative status in standing and sitting). CONCLUSIONS: Adaptation from standing to sitting positions combines pelvic tilt and anteroposterior pelvic translation. THA implantation induces significant changes in SSPT mainly for low- and standard-PI patients. This is an important variable to consider when investigating the causes of THA subluxation or dislocation.

Ultrasound-detected connective tissue involvement in acute muscle injuries in elite athletes and return to play: The French National Institute of Sports (INSEP) study.

OBJECTIVES: Previous MRI studies showed that involvement of connective tissue in muscle injuries may prolong recovery times. The relevance of ultrasound assessment of connective tissue involvement as a prognostic factor is unknown. The aim was to test the hypothesis that ultrasound-detected connective tissue involvement in acute muscle injuries are related to longer recovery times. DESIGN: Cohort study. METHODS: Seventy consecutive elite athletes from the French National Institute of Sports (INSEP) sustaining an acute muscle injury showing positive findings on ultrasound at baseline were included. Ultrasound was systematically performed within 7days after the injury for the assessment of severity (grades 1-4) and type of injury in regard to the absence (M injuries) or presence (C injuries) of connective tissue involvement. The differences in the mean time needed to return to play (RTP) between the different grades and types of injury were assessed using multiple non-parametric tests. RESULTS: When considering the overall grades independently of the type of injury (M or C), an increase in the mean time needed to RTP was observed with the increase of grades (p<0.0001). The same relationship was found when considering grades from M and C injuries separately, with higher grades of injuries exhibiting longer times needed to RTP (p<0.0001). Longer times needed to RTP were observed in athletes demonstrating C injuries in comparison to the ones exhibiting M injuries overall (p=0.002). CONCLUSIONS: Ultrasound-detected connective tissue involvement in acute muscle injuries are related to longer times needed to RTP, especially when disruption is detected.

Does Patients' Perception of Leg Length After Total Hip Arthroplasty Correlate With Anatomical Leg Length?

BACKGROUND: This study assessed the correlation among the patients' perception of the leg length discrepancy (LLD) after total hip arthroplasty (THA) and the anatomical and functional leg length, pelvic and knee alignments, and foot height. METHODS: Patients without significant spinal pathology or previous spine or lower extremity surgery who underwent primary THA (101 patients) were evaluated using EOS images obtained in standing position. All 3-dimensional measures were evaluated and compared for the repeatability and reproducibility and correlation with patients' perception of leg length. RESULTS: In our study, the anatomical femoral length (odds ratio [OR] 0.9, P = .732) did not correlate with patients' perception of the LLD, but other variables like the distance from the middle of the tibial plafond to ground (OR 14.3, P = .003), sagittal knee alignment (OR 1.07, P = .021), and pelvic obliquity (OR 1.05, P = .021) were correlated with the patients' perception of LLD. CONCLUSION: The LLD is a multifactorial complication. We found that the anatomical femoral length as the factor that can be modified with THA technique or choice of prosthesis is not the only important factor. We recommend comprehensive physical examination to investigate spinal deformities, pelvic obliquity, abductor muscle weakness, sagittal and coronal knee alignment, and foot deformity in patients who complain of LLD after THA.

What is the Impact of a Spinal Fusion on Acetabular Implant Orientation in Functional Standing and Sitting Positions?

BACKGROUND: This study used EOS imaging of primary total hip arthroplasty (THA) patients, with and without predating spinal fusion, to investigate (1) the impact of spinal fusion on acetabular implant anteversion and inclination, and (2) whether more extensive spinal fusion (fusion starting above the thoracolumbar junction or extension of fusion to the sacrum) affects acetabular implant orientation differently than lumbar only spinal fusion. METHODS: Ninety-three patients had spinal fusion (case group), and 150 patients were without spinal fusion (controls). None of the patients experienced dislocation. The change in sacral slope (SS) and cup orientation from standing to sitting was measured. RESULTS: Mean SS change from the standing to sitting positions was -7.9°in the fusion group vs -18.4°in controls (P = .0001). Mean change in cup inclination from the standing to sitting positions was 4.9°in the fusion group vs 10.2°in controls (P = .0001). Mean change in cup anteversion from standing to sitting positions was 7.1°in the fusion group vs 12.1°in controls (P = .0001). For each additional level of spinal fusion, the change in SS from standing to sitting positions decreased by 1.6(95% confidence interval [CI], 2.2073-1.0741), the change in cup inclination decreased by 0.8(95% CI, 0.380-1.203), and the change in cup anteversion decreased by 0.9(95% CI, 0.518-1.352; P < .001 in all cases). CONCLUSION: Patients with spinal fusion demonstrated less adaptability of the lumbosacral junction. Longer spinal fusion or inclusion of the pelvis in the fusion critically impacts hip-spine biomechanics and significantly affects the ability to compensate in the standing-to-sitting transition.

Are advanced three-dimensional imaging studies always needed to measure the coronal knee alignment of the lower extremity?

BACKGROUND: Coronal malalignment of the lower extremity is closely related to the onset and progression of osteoarthritis. Restoring satisfactory alignment after tibial osteotomy improves the long-term success of this conservative surgery. The purpose of our study was to determine (1) if there is a difference between two-dimensional (2D) and 3D measurements of the hip-knee-ankle (HKA) angle between the mechanical axes of the femur and the tibia, (2) which parameter most affects 2D-3D HKA measurement, and (3) the percentage of patients who are at risk of error in HKA measurement. METHODS: We reviewed imaging studies of the consecutive patients referred to us for hip or knee pain between June and October 2013. Patients with previous pelvis or lower extremity surgery were excluded. RESULTS: In 51 % (95/186) of lower extremities examined, the 3D method showed more valgus than the 2D method, and in 49 % (91/186), the 3D method showed more varus. In 12 % of extremities (23/186), the knee varus or valgus alignment was completely opposite in 3D images compared to 2D images. Having more than 7° of flexum/recurvatum alignment increased error in 2D HKA measurement by 5.7°. This was calculated to be 0.15° per 1° increase in femoral torsion and 0.05° per 1° increase in tibial torsion. Approximately 20 % of patients might be at risk of error in HKA angle measurement in 2D imaging studies. CONCLUSIONS: Orthopaedic surgeons should assess lower extremity alignment in standing position, with enough exposure of the extremity to find severe alignment or rotational deformities, and consider advanced 3D images of those patients who have them. Otherwise, HKA angle can be measured with good accuracy with 2D techniques. LEVEL OF EVIDENCE: Level-III diagnostic.

The global alignment in patients with lumbar spinal stenosis: our experience using the EOS full-body images.

Lumbar stenosis is frequently observed and treated by spine surgeons. The extent of neurological decompression and the potential spinal fixation are the basic concerns when surgery is planned. But this segmented approach to the problem is sometimes insufficient due to the complex functional situations induced by a sagittal imbalance of the patient and the combination of pathologies known as hip-spine or knee-spine syndromes. A total of 373 consecutive patients included from our EOS and clinical data base. Patients were divided in two groups. Group A included patients presenting exclusive spinal issues (172 cases) out of whom 117 (68 %) had sagittal imbalance. Among 201 patients with associated lower limbs issues (group B), 122 (61 %) had sagittal imbalance. The perception of imbalance was noticed in 54 % (93 cases) in group A and 57 % (115 cases) in group B. In the global series of 239 imbalanced cases, the key point was a spine issue for 165 patients (the 117 patients with only spine problems and 48/122 cases with combined spine and lower limbs problems). But in the patients with combined spine and lower limbs problems, we individualized hip-spine syndromes (24/122 patients) and knee-spine syndromes (13/122 patients). In some cases, (37/122 patients) the anatomical and functional situations were more complex to characterize a spine-hip or a hip-spine problem. The EOS full-body images provide new information regarding the global spinal and lower limbs alignment to improve the understanding of the patient functional posture. This study highlights the importance of the lower limb evaluation not only as compensatory mechanism of the spinal problems but also as an individualized parameter with its own influence on the global balance analysis. Level of evidence IV diagnostic case series.

Total Hip Prostheses in Standing, Sitting and Squatting Positions: An Overview of Our 8 Years Practice Using the EOS Imaging Technology.

More total hip arthroplasty (THA) is performed worldwide and especially in younger and more active patients compared to earlier decades. One of the focuses of THA research in the future will be on optimizing the radiological follow-up of these patients using 2D and 3D measurements of implants position while reducing the radiation dose delivered. Low-dose EOS(®) imaging is an innovative slot-scanning radiograph system providing valuable information in patient functional positions (standing, sitting and even squatting positions). EOS has been proven accurate and reliable without significant inconvenience caused by the metallic artifacts of implants. The ability to obtain precise data on implant orientation according to the patient posture opens new perspectives for a comprehensive analysis of the pelvic frontal and sagittal balance and its potential impact on implants function and failures. We report our 8 years experience on our first 300 THA patients using this technology routinely for pre and post op evaluation. Our results will be compared and confronted with the actual literature about this innovative technology. We shall especially emphasize our experience about patients with abnormal posture and the evolution of the subject over time, because the phenomenon of an aging spine is frequently associated with the process of aging hips.

Ionizing radiation doses during lower limb torsion and anteversion measurements by EOS stereoradiography and computed tomography.

OBJECTIVES: To calculate and compare the doses of ionizing radiation delivered to the organs by computed tomography (CT) and stereoradiography (SR) during measurements of lower limb torsion and anteversion. MATERIALS AND METHODS: A Rando anthropomorphic phantom (Alderson RANDO phantom, Alderson Research Laboratories Inc., Stanford, Conn) was used for the dose measurements. The doses were delivered by a Somatom 16-slice CT-scanner (Siemens, Erlangen) and an EOS stereoradiography unit (EOS-Imaging, Paris) according to the manufacturers' acquisition protocols. Doses to the surface and deeper layers were calculated with thermoluminiscent GR207P dosimeters. Dose uncertainties were evaluated and assessed at 6% at k=2 (that is, two standard deviations). RESULTS: The absorbed doses for the principal organs assessed were as follows: for the ovaries, 0.1 mGy to the right ovary and 0.5 mGy to the left ovary with SR versus 1.3 mGy and 1.1 mGy with CT, respectively; testes, 0.3 mGy on the right and 0.4 mGy on the left with SR versus 8.5 mGy and 8.4 mGy with CT; knees, 0.4 mGy to the right knee and 0.8 mGy to the left knee with SR versus 11 mGy and 10.4 mGy with CT; ankles, 0.5 mGy to the right ankle and 0.8 mGy to the left with SR versus 15 mGy with CT. CONCLUSION: The SR system delivered substantially lower doses of ionizing radiation doses than CT to all the organs studied: CT doses were 4.1 times higher to the ovaries, 24 times higher for the testicles, and 13-30 times higher for the knees and ankles. The use of the SR system to study the torsion of lower limbs makes it possible to reduce the amount of medical irradiation that patients accumulate.

Evaluation of a new low-dose biplanar system to assess lower-limb alignment in 3D: a phantom study.

OBJECTIVE: Knee coronal alignment is routinely assessed on a full-length radiograph of the lower limbs. However, poor positioning of the knee during the procedure affects the accuracy of this kind of measurement, particularly in cases combining knee rotation and flexion. The purpose of this study was to assess the value of a three-dimensional assessment of the hip-knee-ankle (HKA) angle based on a biplanar radiographic system. MATERIALS AND METHODS: A biplanar slot scanning system was used to take radiographs of three lower-limb synthetic models with similar frontal deviation (5° valgus) but different flexion angulations (0°, 9°, and 18°). Biplane acquisitions were done with lower-limb axial rotations ranging from 20° of internal rotation to 20° of external rotation on each of the lower limb models. Three independent observers performed standard 2D measurements of the HKA angle from each anteroposterior (AP) image and also modeled the lower limb in 3D for each biplane acquisition with dedicated software. The HKA angle was automatically calculated from the 3D models. The results of the 2D and 3D techniques were compared. RESULTS: Axial rotation provoked 2D HKA measurement errors up to, respectively, 1.4°, 4.7°, and 6.8° for the lower extremities with 0°, 9°, and 18° flexion, while it never affected the 3D HKA measurement for more than 1.5°. Interobserver errors were 0.7° (SD = 0.5°) for the 2D measurements and 0.6° (SD = 0.4°) for the 3D measurements. CONCLUSIONS: The 3D modeling allows for a more accurate evaluation of coronal alignment compared to 2D, eliminating bias due to wrong knee positioning.