Achieving primary and long-term stability of femoral implant is critical for THA. This can be influenced by the shape and location of surface preparation as well as geometry. The Corail® stem has developed in 1986 in France, which is a straight quadrangular, and full HA coated standard titanium alloy stem featuring a metaphyseal tulip flare in combination with horizontal and vertical grooves. We have performed 75 THAs using it since May 2013. The purpose of this study was to evaluate radiographic changes of femur over time in Japanese patients after THA using this HA coated stem. Between May 2013 and September 2015, we implanted 75 THAs using a Corail® stem (DePuy-Synthes) in 66 patients. Their ages at operation were 47 to 93 years (avg. 66.5 years). Durations of follow up were 6 to 34 months after implantation (avg. 13.7 months). Acetabular components were standard titanium alloy, either 37 Pinnacle Porocoat®, 19 Pinnacle Gription® (DePuy-Synthes), 8 Ranawat®, 5 Regenerex®, or 6 G7® (Zimmer-Biomet) uncemented cups. Heads were either 73 BIOLOX delta® ceramic (CeramTec) or 2 CoCr. Liners were either 56 Marathon® (DePuy-Synthes) or 19 E1® HXLPE (Zimmer-Biomet). We studied 74 hips except one hip which was revised due to infection at the time of 3 weeks after surgery. Postoperative radiographic evaluations were done at the time of 2, 4, 6, 9, 12 months and then every 6 months thereafter. We examined cancellous condensation, radiolucent line, osteolysis, cortical hypertrophy and stress shielding using both of plain X-ray and Tomosynthesis (Shimadzu, Japan).Introduction
Materials and Methods
Between April 2008 and February 2012, we implanted 159 large-diameter MOM stemmed THA with head diameters of 38–50mm. There were 6–38mm, 22–40mm, 42–42mm, 42–44mm, 24–46mm, 13–48mm, 4–50mm, 5–52mm, and one-54mm heads implanted in 138 patients (21 males and 117 females). The pre-operative diagnoses included: 120 OAs, 12 IONs, 4 femoral neck fractures, one RA, and one post-traumatic OA. Their ages were 40–86 years (avg. 63.6 yrs). Follow up was 4 to 67 months post implantation (avg. 40.4 months). All implants were manufactured by one company (Wright Medical Technology, Arlington, TN, USA). The stems were of a standard titanium-aluminum alloy, either 44 ANCA-FIT or 115 PROFEMUR Z non-cemented stems. Acetabular components were all CONSERVE PLUS cobalt-chromium monoblock shells. Heads were also fabricated out of cobalt-chromium alloy, with modular junctions. Patients with complaints of groin pain and/or swelling or hip instability underwent MRI examination in order to detect the presence of fluid collections or soft tissue masses. The statistical correlation between abnormal findings on MRI and age, gender, head diameter, component position and duration post-surgery was performed. 35 hips in 31 patients (22.0%) were found to have either a fluid collection or “pseudotumor” on MRI. These were in 5 males and 26 female patients. According to Hart's MRI classification, they were classified 21 hips in Type 1, twelve hips in Type 2, and two hips in Type 3 (Fig. 1, 2 and 3). 8 hips in 8 patients who had any pseudotumors were undergone revision THA (Fig. 4, 5 and 6). All hips had corrosions at head-neck taper junctions (Fig. 7). There was no difference in age between these two groups of patients (63.7 vs. 63.6 yrs.), but a significant difference in duration from the time of implantation of two groups (23.9 vs. 44.8 months). There appeared to be no significant difference between the mean head diameter of the two groups, 43.2mm and 44.0mm respectively. There was no statistical difference between the two groups with regard to implant orientation: cup inclination 18–70 degrees (41.8 vs. 43.6 degrees); cup anteversion −13–49 degrees (15.1 vs. 14.7 degrees); stem anteversion 2–48 degrees (20.1 vs. 23.3 degrees); and stem offset 17.5–56.2mm (38.2 vs. 37.8mm). Furthermore, according to Lewinnek's safe zone, there was no difference in cup orientation between the two groups (Fig. 8). When we investigated the types of modular neck, the hips having any pesudotumors tended to have long or varus necks. In this study, it is important to emphasize that the appearance of symptoms and development of a pseudotumor occurred early after a MOM THA in some patients. Also it will be important to subject all patients to MRI examination to evaluate the possibility of “silent” fluid collections and pseudotumors. In large-diameter head metal-on-metal stemmed THAs, femoral stems having long or varus neck may contribute to head-neck junction failure.
In 1995, Muller reported on the improvement of metal-on-metal (MOM) bearing over the existing metal-on-polyethylene (MOP) articulations which demonstrated more rapid wear together with granulomatous foreign body reactions, damage of periarticular bony and soft tissues and associated expansile psoas bursal masses. He suggested that adequate lubrication together with improved material properties and manufacturing technologies would bring to the market a superior device with greater longevity. We wish to present our experience with a modern version of a MOM bearing. Between April 2008 and February 2012, we implanted 160 MOM THA with head diameters of 38–50 mm in 139 patients (21 males and 118 females). Their ages were 40–86 years (avg. 63.6 yrs). Follow up was 9 to 53 months post implantation (avg. 28 months). All implants were manufactured by one company (Wright Medical Technology, Arlington, TN, USA). The stems were of a standard titanium-aluminum alloy, either 45 ANCA-FIT or 115 PROFEMUR Z non-cemented stems. Acetabular components were all CONSERVE PLUS cobalt-chromium monoblock shells. Heads were also fabricated out of cobalt-chromium alloy, with modular junctions. Patients with complaints of groin pain and/or swelling or hip instability underwent MRI examination in order to detect the presence of fluid collections or soft tissue masses (Fig. 1 and 2). The statistical correlation between abnormal findings on MRI and age, gender, head diameter, component position and duration post-surgery was performed.[Introduction]
[Material and Methods]
Pseudotumor is a known complication of Metal-on-Metal (MOM) total hip arthroplasty (THA). MRI is usually used to visualize pseudotumor formation. However, small pseudotumors close to the THA components may not be observed using MRI due to image distortion by the interaction between the metallic objects and the magnetic fields. The CT image quality also degrades because MOM THA components can induce X-ray beam-hardening effects. Therefore, we evaluated contrast-enhanced (CE) tomosynthesis. Tomosynthesis is known as an X-ray tomography technique that provides images with fewer metal artifacts and lower X-ray doses for the patients. The aim of this report was to investigate the detectability of pseudotumors by tomosynthesis. A 71-year-old woman had undergone unilateral cementless large-diameter MOM THA using a couple of Conserve Plus acetabular cup and Profemur Z femoral component (Wright Medical, Memphis, Tennessee) for primary arthritis of the left hip at our hospital. She presented with severe hip, groin and buttock pain and swelling at fifteen months after surgery. Therefore, she was examined MRI and tomosynthesis using Sonialvision-Safire X-ray Radiography/Fluoroscopy System (Shimadzu Corporation, Japan). Plain tomosynthesis was obtained before the contrast media injection and followed by CE-tomosynthesis. Then, subtraction tomosynthesis between plain and CE-tomosynthesis were calculated in order to increase the image contrast. The subtraction tomosynthesis image enhanced the pseudotumor visibility, which was considered to be equal to that depicted using MRI (Fig. 1 and 2). However, using MRI, cystic lesions in the pseudotumor appeared as a very high signal in the T2 weighted images, whereas CE-tomosynthesis resulted in no image contrast (Fig. 3). The tomosynthesis image resulted in less image distortion and fewer metal artifacts than MRI, even in the area close to the hip implants.Introduction
Case Report
Recently, as the number of total knee arthroplasty (TKA) is increasing, the number of revision TKA due to loosening or osteolysis is rapidly increasing. Large bone defect is one of the most critical issues during revision TKA. Therefore, early detection of bone loss around the TKA prosthesis before bone loss has been enlarged is very important. However, it is difficult to detect the loosening or ostolysis at the early stage around the femoral component even using fluoroscopically guided plain radiograph. A novel technique of tomography (Tomosynthesis; Shimazu Corporation, Kyoto, Japan) was introduced to detect the small bone loss. The purpose of this study was to examine, in a pig model of radiolucent line and osteolysis around TKA, the sensitivity and specificity of detection of radiolucent line and osteolysis using fluoroscopically guided plain radiographs and a novel technique of tomography. Six cemented femoral components (PFC Sigma; DePuy, Warsaw, IN, USA) were implanted in pig knees. Two components were implanted with standard cement technique (Standard model). Two components were implanted with 2 mm-thick defect between the cement and bone (Radiolucent line model). Two components were implanted with cystic defects (mean size = 0.7 cm3) in femoral condyles (Osteolysis model). The simulated bone lesions were filled with agarose to simulate granuloma tissue and to reduce the air artifact around the bone lesions, which can interfere with imaging techniques (Figure 1). Fluoroscopically guided plain radiographs (63 kV, 360 mA, 50 msec) were taken in 4 postures (antero-posterior, lateral, and +/−45 degrees oblique views) for each specimen (Figure 2). For Tomosynthesis, 74 frames were acquired in the rate 30 frames/sec with fixed X-ray condition (65 kV 1.25 mAs) and were reconstructed (Figure 3). Seven blinded assessors experienced in clinical radiographic analysis examined. The sensitivities, specificities and accuracy of the two imaging techniques were compared.INTRODUCTION
METHODS
Frontal and lateral plain radiographs are the first choice for follow-up observations of the osteotomy boundary that faces the femoral and tibial components of a TKA. However, as plain radiographs provide no information in the image depth direction, it is difficult to determine the exact position of early-stage bone radiolucent lines. A new tomosynthesis technique, which uses both iterative reconstruction and metal extraction methods, has recently attracted attention. We report that this technique provides multi-slice images of the boundary between the metallic implant and the osteotomy surface, which is difficult to observe using conventional multi-slice imaging methods such as CT and MRI, and permits semi-three-dimensional evaluations of polyethylene wear.
We propose digital tomosynthesis with a new reconstruction method, a combination of iterative reconstruction (IR) with metal extraction, in order to reduce metal artifacts with compatibility of high spatial resolution for post-TKA follow-up examination. For comparison of metal artifact reduction efficiency, three images were respectively reconstructed by conventional filtered back projection (FBP), FBP with modified kernel and proposed method. Proposed method provides higher resolution images with remarkably less metal artifacts than others, where we can observe the structure of trabecular bone in the region very close to a metal prosthesis. We demonstrate some clinical applications.
