Dimitris Dimitriou

Early Outcomes of Revision Surgery for Taper Corrosion of Dual Taper Total Hip Arthroplasty in 187 Patients

BACKGROUND Modular dual taper femoral neck designs have been associated with taper corrosion requiring revision surgery. However, outcomes after revision dual taper total hip arthroplasty in patients with symptomatic adverse local tissue reaction due to taper corrosion remain largely unknown. METHODS A total of 198 revision surgeries in 187 patients with dual taper femoral stem total hip arthroplasty with minimum 12-month follow-up were evaluated. RESULTS At mean follow-up of 18 months, at least 1 complication had occurred in 39 patients (20%) of 198 revisions. Single episode of dislocation, treated with close reduction, occurred in 16, whereas 2 patients required rerevision due to multiple dislocations. Infection requiring rerevision occurred in 3 patients. Adverse local tissue reaction recurrence requiring reoperation occurred in 6 patients. Implant survivorship for revision for any cause was 86% at 30 months. The reoperation rate of revised dual taper was 8% (16 out of 198 hips). The median serum levels of cobalt, chromium, and cobalt/chromium ratio decreased (P < .01) from 5.3 μg/L (range: 2.3-48.5 μg/L), 2.6 μg/L (range: 0.2-64 μg/L), and 4.7 (range: 2.1-35) prerevision to 1.4 μg/L (range: 0.2-8.8 μg/L), 0.7 μg/L (range: 0.1-3.9 μg/L), and 2.2 (range: 0.4-8.8) postrevision, respectively. CONCLUSION This pilot study demonstrates that intraoperative tissue necrosis was associated with a high rate of early complications (20%) and revisions (8%), suggesting the importance of a systematic evaluation of these patients including metal ion levels and metal artifact reduction sequence magnetic resonance imaging in optimizing revision outcome, as early diagnosis will facilitate the initiation of appropriate treatment before significant adverse tissue necrosis.

A Novel Preoperative Planning Technique Using a Combination of CT Angiography and Three-Dimensional Printing for Complex Toe-to-Hand Reconstruction.

BACKGROUND Microsurgical toe-to-hand transplantation is a reasonable salvage procedure after failed replantation, though no consensus exists on proper donor toe length for restoration of hand function and optimal donor flap needed for recipient site healing. The purpose of this study was to introduce a novel technique for preoperative planning in complicated toe-to-hand reconstruction and to assess feasibility in four cases. METHODS Computed tomography (CT) angiography was used to map donor site vasculature, whereas CT data were used to create three-dimensional (3D) soft tissue and skeletal models for injured and uninjured hands. Based on the reformatted model (mirror of uninjured hand), soft tissue and finger skeleton models were generated using a 3D printer. An adhesive plaster model was placed on the donor site to determine osteotomy level and incision markings. The skeletal model was used to determine the length of the donor foot resection. Four complex amputation cases were included to illustrate clinical feasibility and early functional and cosmetic outcomes. RESULTS In all four cases, thumb and fingers were reconstructed successfully and all flaps survived. No arterial or venous thrombosis or major donor morbidity were observed. Functional and cosmetic outcomes were satisfactory with similarly satisfactory static two-point discrimination, key pinch and grip strength, and Michigan Hand Outcomes Questionnaire scores. CONCLUSION This novel microsurgical toe-to-hand reconstruction methodology, as introduced in this study, showed promising functional and cosmetic outcomes. Application of this technique in complex hand injuries has the potential to increase surgical efficiency, minimize procedural morbidity, and improve reproducibility.

Asymmetric hip kinematics during gait in patients with unilateral total hip arthroplasty: In vivo 3-dimensional motion analysis

Asymmetric limb loading has been reported in unilateral total hip arthroplasty (THA) patients during gait. However, restoration of 3D motion symmetry of the hip following unilateral THA remains unclear. The purpose of this study was to investigate the in vivo 3D kinematics of the hip in unilateral THA patients during gait. Eight unilateral THA patients were evaluated for both hips during treadmill gait using a dual fluoroscopic imaging system. Reduced hip range of motion in sagittal plane, decreased peak hip extension and asymmetric pelvic rotation of the THA were observed. Furthermore, significant pelvic anterior/posterior tilt asymmetry, higher internal rotation (increased by 8.6°±4.6°) during stance phase and higher adduction (increased by 4.5°±3.2°) during swing phase of the THA were found in this cohort of patients. The results demonstrated that there was 3D motion asymmetry of the hip and pelvis in unilateral THA patients during gait. The data could provide insights into optimizing kinematics and to restoring normal hip function after THA.

In vivo kinematic evaluation of total hip arthroplasty during stair climbing.

Stair climbing is a physically demanding task and a painful limitation for patients suffering from severe hip osteoarthritis. Although total hip arthroplasty (THA) is the definitive treatment for end‐stage osteoarthritis, it is not well understood whether THA restores hip kinematics during strenuous activities. The purpose of this study was to compare the 3D kinematics of THA and native hip during physically demanding tasks and correlate potential differences with THA components orientations/positions in patients with unilateral THA. In vivo hip kinematics were determined during step‐up and leg stance activities using a validated combination of 3D CT‐based computer modeling and dual fluoroscopic imaging system (DFIS). The THA side demonstrated an average 3.4° (±6.5°, range: −5.9° to 15.2°) greater internal rotation than the contralateral native hip, during the step‐up activity but not during leg stance. The difference in internal rotation was highly correlated to the difference in femoral anteversion and anterior translation of hip joint center between implanted and native hip (R2 = 0.71, p < 0.01). The results suggest the importance of accurate THA component placement in restoring normal hip kinematics during functional activities.

Weight-bearing condyle motion of the knee before and after cruciate-retaining TKA: In-vivo surgical transepicondylar axis and geometric center axis analyses.

An equal knee joint height during flexion and extension is of critical importance in optimizing soft-tissue balancing following total knee arthroplasty (TKA). However, there is a paucity of data regarding the in-vivo knee joint height behavior. This study evaluated in-vivo heights and anterior-posterior (AP) translations of the medial and lateral femoral condyles before and after a cruciate-retaining (CR)-TKA using two flexion axes: surgical transepicondylar axis (sTEA) and geometric center axis (GCA). Eleven osteoarthritis (OA) knee patients were studied during a weight-bearing single leg lunge, using a validated dual fluoroscopic imaging system (DFIS) based tracking technique. Eight healthy subjects were recruited as controls. The results demonstrated that following TKA, the medial and lateral femoral condyle heights were not equal at mid-flexion (15-45°, medial condyle lower then lateral by 2.4mm at least, p<0.01), although the knees were well-balanced at 0° and 90°. While the femoral condyle heights increased from the pre-operative values (>2mm increase on average, p<0.05), they were similar to the intact knees except that the medial sTEA was lower than the intact medial condyle between 0° and 90°. At deep flexion (>90°), both condyles were significantly higher (>2mm, p<0.01) than the healthy knees. Anterior femoral translation of the TKA knee was more pronounce at mid-flexion, whereas limited posterior translation was found at deep flexion. These data suggest that a well-balanced knee intra-operatively might not necessarily result in mid-flexion and deep flexion balance during functional weight-bearing motion, implying mid-flexion instability and deep flexion tightness of the knee.

Three-dimensional in vivo difference between native acetabular version and acetabular component version influences iliopsoas impingement after total hip arthroplasty

PurposeThe potential influence of acetabular component orientation on iliopsoas impingement in total hip arthroplasty (THA) has not been previously quantified. The aim of the present study was to utilize pre- and post-operative CT-based 3D models to quantify iliopsoas impingement on acetabular components, and to identify any potential factors associated with iliopsoas impingement.MethodsIliopsoas muscle was modelled from pre-operative CT scans and transferred to the post-operative 3D models in 19 THAs. The volume and the area of the overlap between iliopsoas muscle and acetabular cup (iliopsoas volume & area) was measured on axial and sagittal images. Most protruded lengths of cup uncovered by acetabular bone were measured on axial sagittal scan of CT scans. Version of acetabulum, acetabular cup, and the difference between the two (version difference) were also measured with cup inclination and size. Linear regression analysis was performed to identify any factor influencing iliopsoas impingement.ResultsIliopsoas impingement volume and area were 100.6 ± 226.1 (range, 0.0–663.9) mm³ and 52.6 ± 102.0 (0.0–342.3) mm³, respectively. The protruded lengths on axial and sagittal view were 6.9 ± 5.3 (0.0–16.0) and 2.1 ± 2.7 (0.0–8.0). Linear regression model showed that version difference was significantly related to the iliopsoas impingement volume and area (beta = −0.709, p = 0.041 for volume, and beta = −0.684, p = 0.047 for area).ConclusionsThe results of this study demonstrate that iliopsoas impingement on acetabular components was influenced by the version difference between pre-operative acetabular bone and acetabular component rather than the magnitude of post-operative cup version alone.

Does component alignment affect gait symmetry in unilateral total hip arthroplasty patients

BACKGROUND Component malposition in total hip arthroplasty patients has been associated with adverse clinical outcomes. However, whether the component alignment influences hip dynamic performance following total hip arthroplasty remains unclear. The purpose of this study was to investigate the relationship between the component alignment and in vivo hip kinematics during gait. METHODS Nineteen unilateral total hip arthroplasty patients received CT scan for creation of 3D hip models. The component alignment between the non-implanted and implanted hips were measured and compared. Three-dimensional hip kinematics for both hips of the total hip arthroplasty patients during gait was quantified using a dual fluoroscopic imaging technique. The differences between the implanted and non-implanted hip kinematics during gait were calculated. A forward stepwise multiple linear regression was performed to evaluate the relationships between the changes in implanted hip kinematics and the differences in component alignment with respect to the non-implanted hips. FINDINGS An average 5.1° (SD 6.5°; range -11.1° to 18.3°) increase in internal rotation was observed in the implanted hip than the contralateral non-implanted hip and significantly correlated with a linear combination of the increase of cup anteversion, cup medial translation and leg lengthening (R=0.81). INTERPRETATION Results suggested that the total hip arthroplasty patients compensated the changes in hip geometry by altering the dynamic movement during gait. Restoration of the native hip geometry, including acetabular cup anteversion, position and leg length could be one of the factors that influence the hip kinematics symmetry in total hip arthroplasty patients during gait.

Assessment of accuracy and precision of 3D reconstruction of unicompartmental knee arthroplasty in upright position using biplanar radiography

This study aimed to evaluate the precision and accuracy of 3D reconstruction of UKA component position, contact location and lower limb alignment in standing position using biplanar radiograph. Two human specimens with 4 medial UKAs were implanted with beads for radiostereometric analysis (RSA). The specimens were frozen in standing position and CT-scanned to obtain relative positions between the beads, bones and UKA components. The specimens were then imaged using biplanar radiograph (EOS). The positions of the femur, tibia, UKA components and UKA contact locations were obtained using RSA- and EOS-based techniques. Intraclass correlation coefficient (ICC) was calculated for inter-observer reliability of the EOS technique. The average (standard deviation) of the differences between two techniques in translations and rotations were less than 0.18 (0.29) mm and 0.39° (0.66°) for UKA components. The root-mean-square-errors (RMSE) of contact location along the anterior/posterior and medial/lateral directions were 0.84mm and 0.30mm. The RMSEs of the knee rotations were less than 1.70°. The ICCs for the EOS-based segmental orientations between two raters were larger than 0.98. The results suggest the EOS-based 3D reconstruction technique can precisely determine component position, contact location and lower limb alignment for UKA patients in weight-bearing standing position.

Does haptic robot-assisted total hip arthroplasty better restore native acetabular and femoral anatomy?

The objective was to evaluate whether total hip arthroplasty (THA) using haptic robot assistance restores hip geometry better than the free‐hand technique.

Utility of Preoperative Femoral Neck Geometry in Predicting Femoral Stem Anteversion.

This study investigated the relationships between the preoperative femoral anteversions and the femoral stem anteversion using CT scans and CT-based 3D models to determine whether any preoperative anteversion measurement correlates with the postoperative stem anteversion. Pre-operative and post-operative CT scans of 19 hips with THAs were evaluated. Five preoperative anatomical femoral anteversion measurements (CT-Head, CT-Below Head, CT-Neck, 3D-Head, and 3D-Neck) were compared with the postoperative femoral stem anteversion. The preoperative CT-Neck anteversion measurement was most correlated with the postoperative stem anteversion (r=0.761, P=0.002) with the narrowest ranges of the differences (-10.2° to 11.0°). The preoperative anteversions using the femoral neck geometry from CT scans can be used for the estimation of the postoperative femoral stem anteversion in THA.