Purpose:

In order to acquire good stability of an arthroplasty hip, the proper placement of the implants, which prevents impingement between the stem neck and the socket, is important. In general, the anteversion of the uncemented femoral stem depends on the relationship between the three-dimensional structure of the proximal femoral canal and the proximal stem geometry. The exact degree of the anteversion will be known just after broaching during the operation. If the stem anteversion could be forecasted, preoperative planning of the socket placement would be relatively easy. Furthermore, when a high degree of anteversion is forecasted, a special femoral stem to reduce it, such as a modular stem, could be prepared. However, we experienced that the preoperatively measured anteversion of the femoral neck using computer tomography (CT) was sometimes different from that of the stem measured during the operation. The purpose of this study was to investigate whether the preoperative measurement would be helpful to predict the stem anteversion by examining the relationship between the anteversion of the femoral neck and the stem.

Fracture during total hip arthroplasty occurs partly because the acquisition of fixation at the time of stem implantation depends on the operator's experience and sensation due to the absence of definite criteria. Therefore, an objective evaluation method to determine whether the stem has been appropriately implanted is necessary. We clarified 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 were used. Orthopedists performed stem insertion using a procedure similar to that employed in routine operation. Stress was estimated by finite element analysis using the hammering force calculated from the loading sensor as a loading condition, and frequency analysis of hammering sound data obtained using a microphone was performed (Fig. 1).

Finite element analysis showed a decrease in the hammering sound frequency with an increase in the estimated maximum stress (Fig. 2, 3). When a decrease in frequency was observed, adequate hammering had already been performed to achieve press-fit stability. Therefore, there is a possibility that the continuation of hammering induces intraoperative fractures that become a problem. Based on the relationship between stress and frequency, the evaluation of changes in frequency may be useful for preventing the development of intraoperative fractures.

When a decrease in frequency is observed, the hammering force should be reduced thereafter. 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 bone fracture.

Introduction

Curved varus intertrochanteric osteotomy of the femur is an excellent and minimally invasive method for the treatment of osteonecrosis of the femoral head or osteoarthritis of the hip for joint preservation. However, the early postoperative complications of this procedure may be due to separation at the osteotomy site and an increase in varus angle due to early partial weight bearing.

In recent years, the progressive technology of hemodialysis provides long-term survival for renal failure patients. On the other hand, avascular necrosis of the femoral head from the use of steroids or renal osteodystorophy or femoral neck fracture due to amyloid arthropathy have increased. In such cases, bipolar femoral head prosthesis (FHP) and total hip replacement (THR) are usually performed. But it is at risk of developing severe complications, such as early loosening or infection of the implant.

The aim of this study is to evaluate the stability of the cementless stems in radiograms and clinical results after FHP or THR using three types cementless prosthesis in hemodialysis patients.

The study included 14 patients (19 hips) on hemodialysis who underwent FHP or THR using three types cementless prosthesis at our institution between 1983 to 2005 and we could follow up at least two years. There were 8 women (11 hips) and 6 men (8 hips) with an average age of 43.9 years (range, 20–88). The average follow-up was 6.75 years. The average hemodialysis term was 10.5 years. Three types of hip prosthesis (7 stems were CLS, 6 stems were IMC, 6 stems were Duetto S-I) has been used for the treatment at our institution in the past. The initial diagnosis was avascular necrosis of the femoral head in 8 hips, femoral neck fracture in 5, osteoarthritis in 4 and amyloid arthropathy in two. We assessed at least 3° of varus-valgus deviation or at least 3 mm of subsidence as aseptic loosening of stems, and assessed radiolucent line and stress shielding of the stems in radiograms, also. As for clinical results, we measured postoperative infection rate and revision rate.

Aseptic loosening of stems were identified in 3 hips (15.8%). Radiolucent lines were identified in 5%–26% of hips categolised by Gruen’s classification zone I-VII, although their zones differed according to the stem model. Stress shieldings were identified in 10 hips (53%), most of which were level 1, according to the criteria described by Engh et al. Infection rate and revision rate were 5.3% (1 hip) and it was a long-term hemodialysis patient.

Several studies report, there is a high probability that early loosening of the stems is associated with amyloid deposition. We experienced early loosening of the stems in our case and considered prevention of amyloid deposition very important in improving the prognosis of the arthroplasty. We must follow carefully hemodialysis patients after an operation because their nutrition level is low and their bodies are compromised due to steroids use and their postoperative infection rate is high.

On the basis of observations made in recent years, it can be inferred that the incidence of venous thromboembolism (VTE) in Japan is as high as that in Western countries.

Since 2007, the use of fondaparinux for the prophylaxis of VTE following lower-limb orthopedic surgery has been approved for Japanese patients. This study was performed with an aim to investigate the safety and efficacy of fondaparinux for the prevention of VTE following hip surgery in Japanese patients.

From June 2007 to August 2008, we evaluated 141 consecutive patients (148 hips; average age, 65.6) undergoing total hip replacement (THR), consisted of cementless minimally invasive surgery, and hip fracture surgery (HFS), consisted of open reduction and internal fixation or bipolar hemiarthroplasty. We mainly used 2.5 mg of fondaparinux for a period extending up to 14 days. We estimated the symptomatic VTE and asymptomatic deep-vein thrombosis (DVT) rates in patients by ultrasonography performed on preoperative and postoperative day 3. In addition, we evaluated the pre-operative and postoperative plasma D-dimer levels on days 3, 7, and 14.

We determined that both the preoperative and postoperative incidence of symptomatic VTE was 0%. A D-dimer value of 20 ug/ml or higher was not observed on preoperative days 3 and 7; however, this value was observed in 2 hips on postoperative day 14. The incidence of asymptomatic DVT was observed to be 0.8% preoperatively and 4% postoperatively. In particular, the corresponding value following HFS was observed to be 7.7% preoperatively. The incidence of the hemorrhagic event was observed to be 14.9%. Bleeding was mostly observed in the surgical and drainage areas. An overall major bleeding incidence of 0.7% (1 patient) was observed. The corresponding value in patients in whom the administration of fondaparinux was discontinued by day 14 was 18.9%.

The study results indicate that fondaparinux is useful in Japanese patients for the prevention of VTE following hip surgery. However, the administration of this drug should be accompanied by additional measures to prevent the associated side effect of bleeding.

Several stems have been used for revision of total hip replacement (THR). Moreover, management of proximal femoral bone loss at the time of revision THR remains one of the challenges for hip surgeons. Recently, impaction bone grafting has been suggested to resolve this problem, but it is a demanding technique that results in frequent complications.

We have used the Wagner self-locking stem with cancellous chip allograft for reconstruction of proximal femoral bone defect during revision surgery since 1992.

This study evaluated the midterm results of using Wagner revision stem with bone allograft for femoral revision of THR. We could evaluate forty-one femoral revisions performed between 1992 and 2005 using Wagner revision stem with bone allograft.

All patients had been followed for a minimum of three years with a mean follow-up of 8.6 years. Preoperative radiological femoral bone defects were assessed and classified by Gustillo’s classification. Subsidence of the stem was measured on radiograms taken immediately after revision surgery and again at the latest follow-up. Femoral component fixation was graded as radiographic ingrowth, fibrous stable, or unstable according to the criteria described by Engh et al. The incidence of surgical complications was examined. Allografts were assessed for incorporation into host bone as evidenced by trabecular bridging of the host-graft interface. A clear reduction in density or breakdown of the allograft was defined as bone resorption. Kaplan-Meier survival analysis was performed. The end point was revision because of mechanical loosening of the stem.

Bone defects were classified as: 10 hips type I, 20 hips type II, and 7 hips type III and 4 hips were a periprosthetic fracture. Subsidence was measured at the time of last follow-up in six hips (3, 3, 12, 16, 21, 30 mm). At the latest follow-up 37 of 41 stems were stable. Allograft incorporation could clearly be observed in the proximal femoral bone defects of 31 stems. Three stems were defined as showing bone resorption. Surgical complications included 11 intraoperative fractures, two femoral shafts were perforated during reaming, one dislocation postoperatively, and 3 greater trochanter pseudoarthroses. There was one deep infection, and these cases were excluded from survivorship analysis. One unstable stem and one stem with infection had to be revised. Kaplan-Meier survival was 97.1 % at 10 years.

Wagner self-locking stem with allograft for reconstruction for proximal femoral bone defect in revision surgery is a beneficial procedure. However, because there is a high incidence of intraoperative fractures, surgery should be performed carefully.

The primary fixation of cementless hip prostheses is related to the shape of the stem. When there is a complication of loading in several directions, the mechanical fixation of a hip stem is considered to provide good primary fixation. The purpose of this study was to evaluate whether the IMC stem with its characteristic fixation method, which was developed by a group at Kitasato University, contributes to primary fixation by finite element analysis.

Analysis was performed at a friction coefficient of 0.1 with automatic contact, under the restriction of the distal femoral end. The following three loading conditions were applied:

step loading of the joint resultant force in the region around the hip stem,

Micromotion of the IMC stem along the x-, y-, and z-axes direction was calculated by simulation, and the stress distributed on the stem and femur was determined.

Micromotion along the z-axis, which is a clinical problem in hip prosthesis stems, was lower in the IMC stem than in other stems reported. Micromotion of the stem along the z-axis was low, indicating a low risk of sinking. The interlocking mechanism, which is a characteristic of the IMC stem, functioned to suppress its micromotion, indicating that the locking method of this stem contributed to the stability. Since no stress concentration was detected, it was considered that there are no risks of breakage of the IMC stem and femur.

It was suggested that effective fixation of the finite element model of the IMC stem can be achieved because the micromotion and stress level are appropriate for primary fixation.

Improper rotation of the femoral and tibial components in total knee arthroplasty may leads to various patellofemoral(PF) complications. As for the femoral component, alignment it to the epicondylar axis of the femur has been a widely used method. The tibial component traditionally has been aligned to the medial 1/3 of the tibial tuberosity. However, there is no consensus concerning how to determine the tibial component rotation. The purpose of the current study is to evaluate the influence rotational alignment of tibial component upon PF joint. We divided the cases to two groups. Group A: 41cases 50knees (OA 34cases, RA16cases). The average age was 69.5(35~84). Group B: 30cases 30knees (OA 25 cases, RA 5cases). The average age was 72.6(59~86). In group A, the anteropostrior (AP) axis was defined as the line connecting the medial 1/3 of tibial tuberosity and the center of PCL attachment. In group B, the line connecting the medial edge of patellar tendon attachment and the center of PCL attachment was defined as AP axis. We measured the PF alignment on postoperative X-rays. Tangential radiographs were used to measure the amount of patellar tilt (tilting angle: TA), subluxation and patellar lateral shift (LS).

Group A showed that tilting angle 14±4°, lateral shift 0.3±0. These values of group B were 12±5°,0.2±0.1, respectively.

In rotation of tibial component, Insall reported that the landmark in front of tibia was medial 1/3 tibial tuberosity. Akagi et,, al reported that the landmark was midial edge of patellar tendon attachment. This study indicated that the latter had better alignment in patellofemoral joint.

Management of severe acetabular bone loss at the time of revision total hip replacements (THR) remains has been one of the greater challenges for hip surgeon. Recently, many methods of acetabular reconstruction have been described and various materials are used for supplement of the bone stock deficiency in acetabular revision THR. The purpose of this study was to evaluate the midterm results of the using support ring with bone allografts in acetabular revision THR.

From 1990 to 2005, forty-six acetabular revisions using supporting ring with bone allografts were performed at our institution. All patients were followed up for a minimum of three years with a mean follow-up of 7.5 years. Pre-operative radiological acetabular bone defects were assessed and classified by author’s classification (Itoman’s classification). Radiological analysis involved a general qualitative evaluation. The position of the acetabular reinforcement ring was measured on radiograms, taken immediately after revision surgery and again at the time of last follow-up. Using a MEM template, cranio-central migration and cup inclination angle were measured. Kaplan-Meier survivorship analysis was performed. The end point was revision because of mechanical loosening of the acetabular implant.

Background: It is known that not only the size but also the shape was different between races. We previously compared the distal femur shapes between the American and the Japanese by lateral radiograph and demonstrated the morphological difference in detail. In this study we evaluated the morphologic feature of the lateral and medial condyles separately between the American and the Japanese using MRI in the sagittal plane.

Patients and methods: The subjects were 99 American and 41 Japanese adult women. MRI scan of sagittal section through the distal half of the femur was taken with the slice thickness about 4.0 mm. The envelope curve of each condyle was superimposed to be approximated to an ellipse. The length and inclination of two axes of the ellipse were estimated as the parameters of the statistical comparison.

Results: The ratio major axis/minor axis of the lateral condyles in American women was significantly larger than that in Japanese, while the ratio of the medial condyles in American was significantly smaller. The inclination of the major axis to the anatomical axis of the distal femur in the American lateral condyles were significantly more than that in Japanese lateral condyles, while both the American and Japanese medial condyles showed similar inclination.

Discussion: The morphological feature of both the lateral and medial condyles in American women was significantly different from that in Japanese. The ratio major axis/minor axis and inclination of lateral condyle in American women were different from those in Japanese, while only the ratio was different between the American and Japanese medial condyles. Understanding of these morphological differences between American and Japanese women is beneficial in elucidating discrepancies in normal knee kinematics and in tailoring the design and procedure for successful total knee arthroplasty.

We evaluated the geometry of the resected femoral surface according to the theory for total knee arthroplasty (TKA) using three-dimensional computed tomography (3D CT).

The 3D CT scans were performed in 44 knees indicated as requiring total knee arthroplasty. The 3D images of the femurs were clipped according to the following procedures. The distal femur was cut perpendicular to the mechanical axis at 10 mm proximal from the medial condyle. Rotational alignment was fixed at 3 degrees external rotation from the posterior condylar line. The anterior condyle was resected using the anterior cortex as the reference point. The posterior condyle was cut at 10 mm anterior from the medial posterior condyle.

The medial-lateral (ML) width/anterior-posterior (AP) length was 1.58 ± 0.14 (mean ± SD). AP length of the 3D images tended to be longer than the box length of the three kinds of components provided when the ML width of the images was approximately equal to that of each component. The widths of medial and lateral posterior condyles of the images were 30.1 ± 3.8 mm and 24.8 ± 3.0 mm, respectively. In all except one case, the widths of the resected medial posterior condyles were greater than those of the medial condyles of all components when those of resected lateral posterior condyles were equal to those of the lateral condyles of the components.

The shapes of the resected femoral surface did not always match those of the components. The configuration of Japanese knee joints is different from that of American knee joints. Components with appropriate geometry should be designed for Japanese patients.

Infected hip prosthesis, a devastating complication of primary total hip arthroplasty (THA) can lead to a serious condition. We report here the treatment outcome of our method of two-stage revision THA for infected hip arthroplasty using a temporary antibiotic-impregnated cement spacer for the period between resection and reimplantation.

Between 1996 and 2000, we performed two-stage revision THA using a temporary antibiotic-impregnated cement spacer on eight hips in eight patients with infected hip arthroplasty including hemiarthroplasty, with the infection presenting itself between four days and 19.4 years after last operation. There were four females and four males, with a mean age of 67 years (58 to 72). The mean period of follow-up was 2.5 years (0.3 to 4.3). Cementless THA was implanted as the second srage procedure. Bone defects were restored with frozen allografts. The clinical outcome was evaluated using the hip score of the Japanese Orthopaedic Association (JOA hip score).

The duration of follow-up was 33.9 months (range, 8 to 55 months). The mean JOA hip score at follow-up improved from 32.6 (19 to 74) to 77.1 (59 to 96). The mean interval period was 10.3 weeks (range, 6 to 19 weeks). Seven patients with infected hip arthroplasty successfully received implantation by two-stage cement-less revision THA.

One patient with MRSA infection had a recurrence after four months of revision of THA. However, the two-stage procedure using a vancomicin-impregnated bone cement spacer and beads implantation successfully treated this patient 14 months after the first revision of THA. No recurrence of infection was found at 42 months of follow-up.

These results suggest that two-stage revision THA using a temporary antibiotic-impregnated cement spacer is a useful technique for infected hip arthroplasty.

The aim of this study is to compare the clinical results of the Pin-Sleeve System (AI Wiring System; AIWS) with the Dall-Miles Cable Grip System (DMCGS) for reattachment after dissection of the greater trochanter in hip arthroplasty.

The DMCGS was used in 33 cases 35 hips from 1994 to 1998 and AIWS in 40 cases 42 hips from 1998 to 2001. The age at operation was 61.3 years (24 to 85 years) in the DMCGS group and 67 years (24 to 86 years) in the AIWS group. The postoperative follow-up period was 24 months (4 months to 54 months) in the DMCGS group and 30 months (11 months to 42 months) in the AIWS group.

Bone union failure of the great trochanter occurred in the DMCGS group eight hips (22.9%) and AIWS group five hips (11.9%). The DMCGS group four hips (11.4%) had broken cables, while not even one case of the AIWS group had them (p< 0.05). Fragments from the cable were found in the DMCGS group seven hips (20%) and AIWS group two hips (4.8%). Bone resorption around the cable, grip or sleeve occurred in the DMCGS group 19 hips (54.3%) and AIWS group five hips (11.9%) (p< 0.05). Clinically, the DMCGS group 13 hips (37.1%) and AIWS group seven hips (16.7%) had dysphoria at the greater trochanter; the DMCGS group 17 hips (48.6%) and AIWS group eight hips (19%) had pain at the greater trochanter in the recumbent position with the affected side down (p< 0.05); the DMCGS group 13 hips (37.1%) and AIWS group six hips (14.3%) had pain on exertion.

The AIWS is considered to be a useful implant for reattachment of the greater trochanter compared with the DMCGS.