Takeaki Yamamoto

Prevalence of radiographic findings of femoroacetabular impingement in the Japanese population

BackgroundFemoroacetabular impingement (FAI) is one factor known to cause pain and osteoarthritis (OA) of the hips. Although secondary OA due to hip dysplasia is common among Japanese populations, primary OA is seldom observed. Concomitantly, FAI is also thought to be uncommon in Japan, but relatively few epidemiological studies have addressed this issue. This study aimed to clarify the prevalence of radiographic findings of FAI in a Japanese population and to evaluate whether FAI is a risk factor for the development of arthritic changes.MethodsWe retrospectively examined 87 patients who underwent unilateral hip osteotomy with a Charnley category A hip joint on the contralateral side. Anteroposterior-view radiographs of the non-operated hip joint were assessed for the presence of hip dysplasia, as well as pistol grip deformity and crossover sign indicative of cam-type and pincer-type impingement, respectively. The presence of arthritic changes in the non-operated hip joint was assessed in follow-up radiographs, and factors contributing to the development of arthritis were determined by survival analysis.ResultsOf the 87 hips examined, dysplasia was noted in 38 (43.6%). While no pistol grip deformity was observed, crossover sign, which is indicative of pincer-type impingement, was identified in 9 of 38 dysplastic hips (23.7%) and 15 of 49 non-dysplastic hips (30.6%). Arthritic changes were present in 13 of 38 dysplastic hips (34.2%) and 11 of 49 non-dysplastic hips (22.4%). Survival analysis revealed that the presence of the crossover sign in non-dysplastic hips was significantly associated with the development of arthritis.ConclusionsThe prevalence of the crossover sign in hips in a Japanese population is similar to that reported in Western populations, despite the fact that FAI is believed to be less prevalent in the Japanese population. Furthermore, the presence of the crossover sign in non-dysplastic hip joints is associated with the development of arthritis. Based on our results, pincer-type impingement could be commonly associated with the development of arthritis in Japanese populations.

Radiological evaluation of allograft reconstruction in acetabulum with Ganz reinforcement ring in revision total hip replacement

BackgroundIn revision total hip replacement (THR), cages and rings are commonly used for the reconstruction of bone defects that are due to mechanical loosening of the acetabular cup and migration of the femoral head prosthesis. The purpose of this study was to evaluate the radiological results of the use of Ganz reinforcement rings with bone allografts in acetabular revision THR.MethodsWe reviewed 30 hips of 28 patients who underwent allograft reconstruction of the acetabulum with a Ganz reinforcement ring in revision THR. The average postoperative follow-up period was 8 years. The position of the acetabular socket was measured on anteroposterior radiographs. Loosening of the acetabular component was defined as a change in the cranial or central direction of the cup or a change in the cup inclination angle at the time of last follow-up. In cases of segmental bone defects in weight-bearing areas, we used two or three strut screws prior to incorporation of the Ganz reinforcement ring to act as struts for the ring. Kaplan-Meier survivorship analysis was performed. The end point was revision surgery done because of defined loosening of the acetabular component at the time of the last follow-up.ResultsAll five acetabular components (16.7%) defined as showing aseptic loosening were type D defects (cranio-central defects), but no patient needed revision surgery during the follow-up period. Nine revision surgeries with strut screws for type D acetabular bone defects were performed. The calculated Kaplan-Meier survival rate at 5 years was 96.0%, and the rate at 10 years was 80.2%, using defined loosening of the acetabular component as the end point.ConclusionsAllograft reconstruction of the acetabulum with a Ganz reinforcement ring is a useful technique for revision THR. Occasionally, a special technique (the strut screw technique) was required for the reconstruction of type D bone defects.

Hammering sound frequency analysis and prevention of intraoperative periprosthetic fractures during total hip arthroplasty.

Adequate fixation at the time of cementless stem implantation depends on the operators experience. An objective evaluation method to determine whether the stem has been appropriately implanted may be helpful. We studied the relationship between the hammering sound frequency during stem implantation and internal stress in a femoral model, and evaluated the possible usefulness of hammering sound frequency analysis for preventing intraoperative fracture. Three types of cementless stem (BiCONTACT®, SL-PLUS®, and AI-Hip®) were used. Surgeons performed stem insertion using a procedure similar to that employed in a routine operation. Stress was estimated by finite element analysis, the hammering force was measured, and frequency analysis of hammering sound data obtained using a microphone. Finite element analysis showed a decrease in the hammering sound frequency with an increase in the estimated maximum stress. When a decrease in frequency was observed, adequate hammering had occurred, and the continuation of hammering risked fracture. Based on the relationship between stress and frequency, the evaluation of changes in frequency may be useful for preventing the development of intraoperative fractures. Using our method, when a decrease in frequency is observed, the hammering force should be reduced. Hammering sound frequency analysis may allow the prediction of bone fractures that can be visually confirmed, and may be a useful objective evaluation method for the prevention of intraoperative periprosthetic fractures during stem insertion.

Quality assessment for processed and sterilized bone using Raman spectroscopy

To eliminate the potential for infection, many tissue banks routinely process and terminally sterilize allografts prior to transplantation. A number of techniques, including the use of scanning electron microscopy, bone graft models, and mechanical property tests, are used to evaluate the properties of allograft bone. However, as these methods are time consuming and often destroy the bone sample, the quality assessment of allograft bones are not routinely performed after processing and sterilization procedures. Raman spectroscopy is a non-destructive, rapid analysis technique that requires only small sample volumes and has recently been used to evaluate the mineral content, mineral crystallinity, acid phosphate and carbonate contents, and collagen maturity in human and animal bones. Here, to establish a quality assessment method of allograft bones using Raman spectroscopy, the effect of several common sterilization and preservation procedures on rat femoral bones were investigated. We found that freeze–thawing had no detectable effects on the composition of bone minerals or matrix, although heat treatment and gamma irradiation resulted in altered Raman spectra. Our findings suggest Raman spectroscopy may facilitate the quality control of allograft bone after processing and sterilization procedures.

Two-Stage Revision Total Hip Arthroplasty for Periprosthetic Infections Using Antibiotic-Impregnated Cement Spacers of Various Types and Materials

Antibiotic-impregnated hip cement spacers of various types and materials have been used in the treatment of periprosthetic hip infections. We developed a handmade spacer by using polymethylmethacrylate (PMMA) and/or α-tricalcium phosphate (α-TCP). In this study, we retrospectively reviewed the surgical outcomes in 36 consecutive patients treated with 2-stage revision total hip arthroplasty by using our antibiotic-impregnated hip cement spacers. We aimed to analyze the infection control and reinfection rates after revision surgery. Moreover, we analyzed the possible predictors of postoperative reinfection. After exclusion of 1 patient who died immediately after the first-stage surgery, infection was controlled in 33 of the 36 hips (success rate, 91.7%). Two of these 33 hips underwent resection arthroplasty. Of the 36 hips that had been treated with the antibiotic-cement spacer, 31 hips (86.1%) were eligible for the second-stage prosthesis re-implantation. The 31 protocol hip joints of patients followed up for >6 months (mean, 48.6 months). Ten of these 31 hips (32.3%) became reinfected. No possible predictor examined differed significantly between the reinfection-positive and reinfection-negative groups. However, spacers consisting of PMMA cement alone were associated with the highest risk of reinfection. Therefore, α-TCP-containing antibiotic-impregnated hip cement spacers might decrease the reinfection rate in patients undergoing re-implantation.

Revision total hip replacement using a cementless interlocking distal femoral stem with allograft-cemented composite and the application of intramedullary and onlay cortical strut allografts: two case reports.

Abstract It is often difficult to perform repeated revision total hip replacement (re-THR) after prosthesis loosening stemming from infection, mechanical loosening, and osteolysis. Reasons for this include the size of the bone defect and poor quality of the remaining bone. We have previously performed revision surgery using a cementless interlocking distal femoral stem with segmental cortical allograft-cemented composite for reconstruction in the presence of circumferential bone loss of the proximal femur according to Gustilo classification type IV [1]. However, in the case where the distal femur had a stovepipe canal due to osteoporosis, osteolysis, and infection, it was difficult to achieve stable fixation to the distal femoral cortical bone using a cementless interlocking distal femoral stem. Therefore, a cortical strut allograft is inserted into the femoral bone canal on the medial side, followed by the insertion of an interlocking stem. A further cortical strut allograft is inserted on the lateral side of the distal femur. In addition, the distal onlay allograft should pass over the allograft–host bone junction. The two allografts are finally secured with interlocking screws. The bone allografting to augment femoral bone deficiency was performed using mainly cadaveric bone allografts obtained from our bone bank [2, 3]. In this report, we describe two cases of re-THR involving the use of intramedullary and onlay cortical strut allografts with a cementless interlocking distal femoral long stem to achieve favorable fixation stability. The two patients were asked if the data from the case could be submitted for publication, and both gave their consent

Comparison of Gait Motion Including Postoperative Trunk Deflection Between Direct Lateral and Anterolateral Approaches in Supine Total Hip Arthroplasty

BACKGROUND A prospective study was conducted to compare the effect of an anterolateral approach in the supine position (ALS) with that of a direct lateral (DL) approach on gait motion, including trunk deflection, in walking after total hip arthroplasty. We hypothesized that trunk deflection in walking after ALS would be significantly improved in comparison with use of the DL approach. METHODS The subjects were 15 patients, with 7 in the ALS group and 8 in the DL group. Walking before and 9 and 28 weeks after surgery was analyzed using 3-dimensional motion analysis. RESULTS Walking velocity, stride length, hip joint range of motion in the sagittal plane in walking, and locomotion range of trunk inclination were significantly improved 28 weeks after surgery in both groups. In gait analysis, there were no significant differences between the 2 groups. CONCLUSION This study was conducted to compare the effect of ALS with that of a DL approach on locomotion in walking after total hip arthroplasty. Hip pain at 9 weeks after surgery was significantly improved using ALS compared to the DL approach, but there were no significant differences in gait function at 28 weeks after surgery using ALS or DL approach. Further long-term studies are required to examine differences between these procedures.

Long-term clinical and radiographic results of the cementless Spotorno stem in Japanese patients: A more than 15-year follow-up:

Purpose: Although previous studies have reported encouraging results of cementless Spotorno (CLS) stem, studies with more than 15 years of follow-up are rare. The objective of this study is to investigate the long-term results of CLS stem and the factors potentially influencing the outcomes. Methods: The clinical and radiographic data of 79 hips (64 patients) were reviewed. Clinical outcome was determined using the Japanese Orthopedic Association’s hip scoring system (JOA hip score). Survival rate was assessed by Kaplan–Meier survival analysis. The main end point for survival analysis was revision of stem. The correlations between patient demographics, radiographic factors, and stem survival rates were analyzed. Results: At a mean follow-up period of 20.1 years, the mean JOA hip score at final follow-up was 84.7 points. Stem survival rate for all revisions was 97.5% at 20 years, and stem survival for aseptic loosening was 98.9%. Varus alignment had a significant negative influence on the survival of the femoral stem. Conclusion: This study demonstrates acceptable long-term clinical and radiographic results of the CLS stem in Japanese patients. Caution should be exercised to avoid varus stem alignment.

Early fracture of the modular neck of a MODULUS femoral stem

We present the case of a 46-year-old woman who underwent revision surgery approximately 4 years after total hip arthroplasty because of a fracture of the modular neck of a MODULUS femoral stem. The fractured surfaces of the retrieved implant were inspected using optical and scanning electron microscopy. Three-dimensional finite element analysis was also performed to identify the stresses that might have caused the failure. We concluded that active, obese patients who are implanted with a high-offset, small-sized modular component could experience stress-induced fractures of the modular neck, with proper fixation and osseointegration of the distal stem, especially if residual bone or tissue is present on the inner surface of the neck that could contribute to micromovement and decreased proximal fixation.

Early gait analysis after curved periacetabular osteotomy for acetabular dysplasia

License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Orthopedic Research and Reviews 2015:7 25–32 Orthopedic Research and Reviews Dovepress