Tomofumi Nishino

Midterm results of the Synergy cementless tapered stem : stress shielding and bone quality

BackgroundTapered femoral stems have been shown to produce less thigh pain and stress shielding than other cement-less stem designs. The purpose of this study was to examine the performance of this type of femoral stem in Japanese patients.MethodsA series of 40 total hip arthroplasties with a Synergy tapered femoral component were performed in 33 patients between March 1999 and February 2001 at our institution. Three hips (in three patients) were lost to follow-up, so 37 hips in 30 patients were followed for an average of 70 months. The patients’ average age at the time of surgery was 59 years (range 43–80 years). Clinical evaluation included the Japanese Orthopaedic Association (JOA) Hip Score and the incidence of thigh pain. Preoperative radiographic examination included the cortical index and Dorr’s bone type. Postoperative radiographic examination included evaluation of biological fixation, spot welds, cortical hypertrophy, and stress shielding.ResultsThe average JOA Hip Score improved significantly from 35 preoperatively to 91 postoperatively. No patient suffered thigh pain. All femoral components were classified as bony stable. Spot welds and cortical hypertrophy were commonly found in the middle to the distal portion of the component. Severe (third and fourth degree) stress shielding was observed in 24.3% of the cases. A low cortical index, a Dorr type C femur, and a large stem size were associated with severe stress shielding.ConclusionsThe midterm clinical results with the Synergy femoral component were satisfactory for Japanese patients. Although severe stress shielding was frequently observed in patients with poor bone quality, stem stability was not affected. Extent of grit blasting and stem length may be factors causing severe stress shielding in Japanese patients with poor bone quality. In conclusion, poor bone quality is a less favorable indication for the cementless tapered stem.

Follow-Up Results of 10–12 Years After Total Hip Arthroplasty Using Cementless Tapered Stem — Frequency of Severe Stress Shielding With Synergy Stem in Japanese Patients

Synergy stems are tapered stems featuring a proximal porous coating, grid blasting below the proximal third to the distal end. This study included 41 patients (50 hips) who underwent total hip arthroplasty with follow-ups for 10 years or more. No stem reimplantations were performed. Spot welds were observed in the distal stem in Gruen zones 3 and 5 in 35 and 32 hips, respectively. First-degree stress shielding occurred in 8 hips; 2nd-degree, 20 hips; 3rd-degree, 13 hips; and 4th-degree, 9 hips. Because of bone fixation to the distal grit-blasted section of the stem, severe stress shielding was observed in nearly half of the cases. Multiple regression analysis of stress shielding determinants revealed a correlation between stem size and short patient height, showing the cause of stress shielding to be a mismatch in size between the stem and the femoral bone.

Osseointegration of porous titanium implants with and without electrochemically deposited DCPD coating in an ovine model

BackgroundUncemented fixation of components in joint arthroplasty is achieved primarily through de novo bone formation at the bone-implant interface and establishment of a biological and mechanical interlock. In order to enhance bone-implant integration osteoconductive coatings and the methods of application thereof are continuously being developed and applied to highly porous and roughened implant substrates. In this study the effects of an electrochemically-deposited dicalcium phosphate dihydrate (DCPD) coating of a porous substrate on implant osseointegration was assessed using a standard uncemented implant fixation model in sheep.MethodsPlasma sprayed titanium implants with and without a DCPD coating were inserted into defects drilled into the cancellous and cortical sites of the femur and tibia. Cancellous implants were inserted in a press-fit scenario whilst cortical implants were inserted in a line-to-line fit. Specimens were retrieved at 1, 2, 4, 8 and 12 weeks postoperatively. Interfacial shear-strength of the cortical sites was assessed using a push-out test, whilst bone ingrowth, ongrowth and remodelling were investigated using histologic and histomorphometric endpoints.ResultsDCPD coating significantly improved cancellous bone ingrowth at 4 weeks but had no significant effect on mechanical stability in cortical bone up to 12 weeks postoperatively. Whilst a significant reduction in cancellous bone ongrowth was observed from 4 to 12 weeks for the DCPD coating, no other statistically significant differences in ongrowth or ingrowth in either the cancellous or cortical sites were observed between TiPS and DCPD groups.ConclusionThe application of a DCPD coating to porous titanium substrates may improve the extent of cancellous bone ingrowth in the early postoperative phase following uncemented arthroplasty.

Joint distraction and movement for repair of articular cartilage in a rabbit model with subsequent weight-bearing

We have previously shown that joint distraction and movement with a hinged external fixation device for 12 weeks was useful for repairing a large articular cartilage defect in a rabbit model. We have now investigated the results after six months and one year. The device was applied to 16 rabbits who underwent resection of the articular cartilage and subchondral bone from the entire tibial plateau. In group A (nine rabbits) the device was applied for six months. In group B (seven rabbits) it was in place for six months, after which it was removed and the animals were allowed to move freely for an additional six months. The cartilage remained sound in all rabbits. The areas of type II collagen-positive staining and repaired soft tissue were larger in group B than in group A. These findings provide evidence of long-term persistence of repaired cartilage with this technique and that weight-bearing has a positive effect on the quality of the cartilage.

Effect of gradual weight-bearing on regenerated articular cartilage after joint distraction and motion in a rabbit model.

The purpose of this study was to clarify the effect of gradual weight bearing (GWB) on regenerating cartilage. We developed a novel external fixation device (EFD) with a controllable weight‐bearing system and continuous passive motion (CPM). A full‐thickness defect was created by resection of the entire articular surface of the tibial plateau after the EFD was fixed in the rabbits left knee. In the GWB group (n = 6), GWB was started 6 weeks after surgery. In the CPM group (n = 6), CPM with EFD was applied in the same manner without GWB. The control group (n = 5) received only joint distraction. All rabbits were sacrificed 9 weeks after surgery. The central one‐third of the regenerated tissue was assessed and scored blindly using a grading scale modified from the International Cartilage Repair Society visual histological assessment scale. The areas stained by Safranin‐O and type II collagen antibody were measured, and the percentage of each area was calculated. There was no significant difference in the histological assessment scale among the groups. The percentage of the type II collagen‐positive area was significantly larger in the GWB group than in the CPM group. The present study suggests that optimal mechanical stress, such as GWB, may affect regeneration of cartilage, in vivo.

Location of fractures and the characteristics of patients with atypical femoral fractures: analyses of 38 Japanese cases

The purpose of this study was to determine fracture location and the characteristics of patients with atypical femoral fractures (AFFs). We studied 38 AFFs in 34 patients admitted to our institution between November 2007 and July 2013. The diagnostic criteria for the AFFs were based on 2014 American Society of Bone and Mineral Research guidelines. We classified the fracture location as proximal, middle, or distal to trisect the femoral diaphysis from just distal to the lesser trochanter to just proximal to the supracondylar flare. Bowing was defined as a line through the inside of the tip of the great trochanter and a condylar center that was outside the medullary cavity. We investigated the fracture’s location, existence of coronal bowing, and bisphosphonates (BPs), glucocorticoids (GCs), and proton pump inhibitors therapy. We analyzed associations between fracture location and demographic and clinical factors. Twelve fractures were proximal, 25 were middle, and one was distal. Nineteen limbs showed femoral bowing. Thirty-one patients received BP treatment—20 patients received alendronic acid, eight risedronic acid, and three minodronic acid. Fourteen patients received a GC, and 16 received a proton pump inhibitor. There was a significant association between coronal bowing and middle fracture locations, GC therapy and proximal fracture locations, and older age and middle fracture locations. Tall height and heavy weight had an association with proximal fracture location, and short height and light weight had an association with middle fracture location. In conclusion, we provide evidence supporting a causal relationship between BP-related severely suppressed bone turnover and AFFs. We also provide evidence supporting additional influences from altered distribution of mechanical stress with femoral bowing and various factors, such as GC therapy, age, body weight, and height, which might negatively affect bone intensity and quality and result in fracture.

Effectiveness of bone marrow transplantation for revitalizing a severely necrotic small bone: experimental rabbit model

BackgroundAlthough treating Kienböck disease is controversial, we previously applied a new method that was less invasive and comprised drilling, bone marrow (BM) transplantation, external fixation, and radiating low-intensity pulsed ultrasound. We reported good clinical results obtained by this new method, which were comparable to those obtained using other, rather invasive methods. Here, we investigated the effect of drilling holes and transplanting BM into necrotic bone in an animal model to further understand the effect of these methods on the revitalization of necrotic bone.MethodsWe used rabbit fourth tarsal bones, whose surfaces consist of cartilage and cortical bone, mimicking human lunate bone. We soaked the retrieved bones in liquid nitrogen to induce necrosis. After thawing, we inserted them separately into bilateral subcutaneous pouches in the backs of rabbits. A total of 60 rabbits were divided into four groups of 15 rabbits each: BM transplantation (BM group); peripheral blood transplantation (PB group); drilling (D group); control (C group). We sacrificed three rabbits to obtain six specimens in each group at 2, 4, 8, 12, and 20 weeks after operation and evaluated the specimens histomorphologically.ResultsIn the BM group, significantly larger mineralizing surfaces, osteoblast surfaces, and osteoclast numbers were observed at 4, 8, and 12 weeks compared with those in the other groups. No significant differences were observed at 2 and 20 weeks in the groups except the mineralizing surface of the 20-week-BM group, which was significantly greater.ConclusionsWe examined the efficacy of drilling and of BM transplantation for regenerating necrotic bone in a rabbit model. Our experiments suggest that drilling with BM transplantation to the necrotic bone accelerates bone formation and remodeling.

The use of a novel in-bed active Leg Exercise Apparatus (LEX) for increasing venous blood flow.

Objective: The incidence of pulmonary embolism (PE) and leg deep vein thrombosis (DVT) has increased in recent years in association with aging and an increase in the number of bedridden individuals. We developed an active in-bed leg exercise apparatus labeled the Leg Exercise Apparatus (LEX) for DVT prevention. We compared the effect of leg exercises performed using the LEX to conventional active ankle exercises on increased blood flow. Materials & Methods: The subjects were eight healthy adult volunteers [five men and three women, aged 20–34 (mean 27.0) years]. Subjects performed two types of exercise; exercise 1 consisted of leg exercises using the LEX, while exercise 2 consisted of in-bed active plantar flexion/dorsiflexion exercises without the device. Measurements were taken 1, 5, 10, 20, and 30 minutes after exercise including common femoral vein blood flow, mean blood flow velocity, maximum blood flow velocity, and vessel diameter using Doppler ultrasound. Statistical procedures included timed measurement data analysis using a linear mixed model. A Bonferroni correction was used for multiple comparisons. Results: Compared to resting levels, blood flow reached a maximum value 1 minute after exercise for both exercise types, with a significantly greater increase after exercise 1 (1.76-fold increase) compared to exercise 2 (1.44-fold increase) (p = 0.005). There was a significant difference (p = 0.03) between the two exercises for all values from 1 minute to 30 minutes following exercise. There was no significant difference between exercises for peak or mean blood flow velocity. Compared to resting levels, blood vessel diameter reached a maximum value of 1.47-fold greater at 5 minutes post-exercise for exercise 1 and a maximum value of 1.21-fold greater at 1 minute post-exercise for exercise 2. Conclusions: Exercise using the LEX increased lower leg venous blood flow and vessel diameter. We propose that the LEX may serve as a new DVT prevention tool.

The 21- to 27-year results of the Harris-Galante cementless total hip arthroplasty

BACKGROUND The Harris-Galante total hip arthroplasty (THA) is a first-generation cementless THA with a porous coating for biological fixation of the implant. Many studies report excellent long-term results for the acetabular cup, but few long-term studies exist for the femoral stem because of relatively poor short-term and midterm results. Here we present the 21- to 27-year results of the cup and the stem of the Harris-Galante THA. METHODS From 1985 to 1991, 102 Harris-Galante THAs were inserted in 82 patients. At the time of the THA, the mean patient age was 54 years (range, 20-78 years). The primary diagnosis was secondary osteoarthritis due to developmental hip dysplasia (69 [68%] hips). The Japanese Orthopaedic Association (JOA) hip score and thigh pain were measures of clinical outcome. Radiographic review was performed retrospectively. Implant survival was evaluated by Kaplan-Meier analysis. RESULTS Of 102 hips, 35 hips were from 31 deceased patients, 5 patients (6 hips) were lost to follow-up, 12 hips were revised, and 49 hips were from patients living at the latest follow-up. Among the living patients, 36 hips had a clinical evaluation and 42 hips had a radiograph obtained more than 21 years. The JOA hip score improved from 42 points preoperatively to 83.5 points at the latest follow-up. Thigh pain was reported in 13 hips. One cup and four stems were loose at the latest radiographic review. Most cup revisions were related to acetabular osteolysis. Fifteen hips showed severe stress shielding. Kaplan-Meier analysis of survivorship with any revision, acetabular reoperation, stem revision, and stem loosening as the end point was 87.0%, 90.3%, 95.7% and 86.4%, respectively, at 24.6 years. CONCLUSIONS Long-term implant survival and clinical results of the Harris-Galante THA were good. Acetabular osteolysis-related cup loosening was a problem of the cup. Loosening, thigh pain, and stress shielding were problems of the stem.

Initial Results of an Acetabular Center Axis Registration Technique in Navigated Hip Arthroplasty with Deformed Acetabular Rims

Background In cementless total hip arthroplasty, imageless computer-assisted navigation is usually used to register the anterior pelvic plane (APP). The accuracy of this method is influenced by the subcutaneous tissues overlying the registration landmarks. On the other hand, the acetabular center axis (ACA) is determined from the acetabular rim. Precise registration of the ACA is possible because of direct palpation using a pointer. Imageless navigation using the ACA usually targets patients with normal acetabular morphology. The aim of this study was to investigate the accuracy of imageless navigation using the ACA instead of the APP in patients with normal or deformed acetabular rims. Methods The intraoperative cup position was compared with that obtained from the postoperative computed tomography (CT) images in 18 cases. Results The inclination angle derived from the navigation system was 3.4 ± 5.3 degrees smaller and the anteversion angle was 1.4 ± 3.1 degrees larger than those derived from the CT images. Conclusion The inclination cup angle of the navigation system was significantly inferior to the true value, particularly in cases with large anterior osteophytes.