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Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_6 | Pages 21 - 21
1 Apr 2018
Yamashita S Cho C Mori T Kawasaki M
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Introduction

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in knee and hip prostheses after total joint replacement is one of the major restriction factors on the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear of UHMWPE. A number of studies have investigated the factors influencing the wear of UHMWPE acetabular cup liner in hip prosthesis. Most of these studies, however, have focused on the main articulating surfaces between the femoral head and the polyethylene liner.

Materials and Methods

In a previous study (Cho et al., 2016), the generations of cold flow into the screw holes in the metal acetabular cup were observed on the backside of the retrieved UHMWPE acetabular cup liners as shown in Figure 1. We focused on the screw holes in the metal acetabular cup (Figure 2) as a factor influencing the wear behavior of polyethylene liner in hip prosthesis. In this study, computer simulations of the generation of cold flow into the screw holes were performed using the finite element method (FEM) in order to investigate the influence of the screw holes in the metal acetabular cup on the mechanical state and wear behavior of polyethylene liner in hip prosthesis.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_6 | Pages 20 - 20
1 Apr 2018
Eto T Cho C Mori T Kawasaki M
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Introduction

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE in the human body after total joint replacement causes serious clinical and biomechanical reactions. Therefore, the wear phenomenon of UHMWPE is now recognized as one of the major factors restricting the longevity of artificial joints. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE.

Materials and Methods

In a previous study (Cho et al., 2016), it was found that roundness (out-of-roundness) of the retrieved UHMWPE acetabular cup liner [Figure 1(a)] had a tendency to increase with increasing roundness of the retrieved metal femoral head [Figure 1(b)]. It appears that roundness of the femoral head contributes to increase of wear of the polyethylene liners. We focused on the roundness of femoral head as a factor influencing the wear of polyethylene liner in hip prosthesis. In this study, further roundness measurements for 5 retrieved metal femoral heads were performed by using a coordinate measuring machine. The elasto-plastic contact analyses between femoral head and polyethylene liner using the finite element method (FEM) were also performed in order to investigate the influence of femoral head roundness on the mechanical state and wear of polyethylene liner in hip prosthesis.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_6 | Pages 23 - 23
1 Apr 2018
Cho C Mori T Kawasaki M
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Introduction

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight- bearing surfaces in total joint replacement. However, the wear of UHMWPE and the polyethylene wear debris generated in the human body after total joint replacement cause serious clinical and biomechanical reactions.

Therefore, the wear phenomenon of UHMWPE in total joint replacement is now recognized as one of the major factors restricting the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE.

Materials and Methods

The wear and/or failure characteristics of 33 retrieved UHMWPE acetabular cup liners of hip prostheses were examined in this study. The retrieved liners had an average in vivo duration of 193.8 months (75 to 290 months). Several examples of the retrieved liners are shown in Figure 1. The elasto-plastic contact analyses between metal femoral neck and polyethylene liner and between metal femoral head and polyethylene liner using the finite element method (FEM) were also performed in order to investigate the factors influencing the wear and/or failure mechanism of the polyethylene liner in hip prosthesis.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_6 | Pages 22 - 22
1 Apr 2018
Baba S Cho C Mori T Kawasaki M
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Introduction

Wear phenomenon of ultra-high molecular weight polyethylene (UHMWPE) in hip and knee prostheses is one of the major restriction factors on the longevity of these implants. In retrieved hip prostheses with screw holes in the metal acetabular cup for fixation to the pelvis, the generation of cold flow into the screw holes is frequently observed on the backside of the UHMWPE acetabular cup liner. In most retrieved cases, the protruded areas of cold flow on the backside were located on the reverse side of the severely worn and deformed surface of the polyethylene liner. It would appear that the cold flow into screw holes contributes to increase of wear and damages of the polyethylene liner in hip prosthesis.

Methods

In a previous study (Cho et al., 2016), we pointed out the generation of cold flow into the screw holes on the backside of the retrieved UHMWPE acetabular cup liner as shown in Figure 1. The primary purpose of this study was to investigate the influence of the cold flow into the screw holes on the wear of the polyethylene liner in hip prosthesis. In this study, computer simulations of the generation of cold flow were performed using the finite element method (FEM) in order to propose the design criteria about the cold flow of the hip prosthesis for improving the wear resistance of the polyethylene liner. We especially focused on the influence of polyethylene thickness and contact surface conformity on the generation of cold flow into the screw hole.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 54 - 54
1 Feb 2017
Kawano T Mori T
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Purpose

Degenerative osteoarthritis of the knee usually shows arthritic change in the medial tibiofemoral joint with severe varus deformity. In TKA, the medial release technique is often used for achieving mediolateral balancing, but there is some disagreement regarding the importance of pursuing the perfect rectangular gaps. Our hypothesis is that the minimal release especially in MCL is beneficial regarding on retaining the physiological medial stability and knee kinematics, which leads to improved functional outcome. Therefore, the purpose of this study is to examine the thickness of the tibia resection if the extent of the medial release is minimized to preserve the medial soft tissue in TKA.

Patients and Methods

Thirty TKAs were performed for varus osteoarthritis by a single surgeon. In the TKA, femoral bone was prepared according to the measured resection technique, bilateral meniscus and anterior cruciate ligament were excised. After the osteophytes surrounding the femoral posterior condyle were removed, the knee with the femoral trial component was fully extended and the amount of the tibial bone cut was decided for the 10mm tibial insert by referring to the medial joint line of the femoral trial component. After the every bone preparation and placement of all the trial components, If flexion contracture due to the narrow extension gap was found, additional tibial bone cut or medial soft tissue release were performed.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 55 - 55
1 Feb 2017
Kawano T Furusho H Mori T
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Introduction

The issue regarding whether suction drainage should be used during TKA continues to be debated as both methods have disadvantages. The use of a drain may increase estimated blood loss and incidence of blood transfusion, while no drainage may be associated with ecchymosis formation surrounding the surgical site and wound problems. This prospective randomized study aimed to clarify the need for suction drainage in TKA by assessing the short-term postoperative outcome.

Patients and Methods

We randomized 39 patients undergoing TKAs either with or without an intra-articular suction drain and divided to two groups. All the TKAs were performed by a single surgeon using cemented prostheses. As the perioperative blood management, air tourniquet was used during surgery, the knee arthrotomy was closed water-tightly, and all the patients were received both intra-articular and intra-venous administrations of tranexamic acid. After the surgery, a bulky compression dressing was applied to prevent the third space leakage of the blood for four days and rivaroxaban was used for venous thromboembolism prophylaxis for one week. The two groups were compared in terms of hemoglobin decrease, recovery of knee flexion, postoperative pain, and examined both the knee circumference and knee swelling. The incidence of short-term complications also evaluated.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_10 | Pages 144 - 144
1 May 2016
Yoshioka T Okimoto N Fuse Y Kawasaki M Mori T Majima T
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The objective of this study is to compare three dimensional (3D) postoperative motion between metal and ceramic bipolar hip hemiarthroplasty for femoral neck fracture.

Materials and Methods

This study was conducted with forty cases (20 cases of metal bipolar hemiarthroplasty (4 males, 16 females), 20 cases of ceramic bipolar hemiarthroplasty (2 males, 18 females)) from November 2012 to November 2014. Average age was 80.8±7.5 years for the metal bipolar group and 79.3±10.5 years for the ceramic bipolar group. We obtained motion pictures from standing position to maximum abduction in flexion by fluoroscopy then analyzed by 2D–3D image matching method. The motion range of the “Shell angle”, “Stem neck angle” and the “Stem neck and shell angle” has been compared between the metal bipolar group and the ceramic bipolar group (Fig. 1).

Results

Metal bipolar showed greater variability of the Stem neck angle and Shell angle than ceramic bipolar. Six of the twenty cases reached unilateral oscillation angle of 37 degrees in metal bipolar. In other words, 30% of metal bipolar group revealed neck-shell impingement. No case reached oscillation angle of 58 degrees in ceramic bipolar group. There was no significant difference between the metal bipolar group and the ceramic bipolar group with respect to the difference of minimum and maximum angle of Stem neck angle (movement range of the stem neck) and Shell angle (movement range of the bipolar cup). On the other hand, difference of minimum and maximum angle of the Stem neck and shell angle (movement range of the inner head) was significantly greater in the metal bipolar group than the ceramic bipolar group. Movement, range of bipolar shell was significantly greater than that of inner head in both groups (Table 1).


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 55 - 55
1 May 2016
Mori T Kudo H Iwasawa M
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The aim of this study was to assess the long-term results of the Kudo type-5 total elbow prosthesis and compare the results of two types of cemented ulnar components.

The Kudo type-5 unlinked total elbow prosthesis (Biomet UK Ltd, Bridgend Wales) was developed in 1993. The stem of humeral component is porous-coated with a plasma spray of titanium alloy for cementless use. The ulnar component may be metal-backed with a porous-coated stem or polyethylene alone; the latter designed mainly for cement use. A metal-backed type without a porous-coated stem designed for cement use also came into being after 2003.

Between 1993 and 2010, the Kudo type-5 total elbow arthroplasty was performed on 364 elbows in 274 consecutive patients with rheumatoid arthritis. The mean age of the patients at the time of the operation was 60.7 (27–86) years. Twenty elbows had Larsen grade III, 224 had grade IV, and 120 had grade V changes pre-operatively. Before the operation, 346 elbows had severe or moderate pain, 95 had gross valgus-varus instability. Clinical symptoms and revision rates were assessed 4 to 20 years (mean, 9 years) postoperatively. The mean Mayo elbow performance scores were all poor except for three initially (mean overall score, 39.5 points). The overall score had improved substantially both at the early follow-up (1 to 3 years after the operation) and the latest follow-up (4 to 20 years after the operation), with 89.5 and 84.7 points, respectively. At the latest follow-up the overall result was excellent for 185 elbows, good for 103, fair for 11 and poor for 30, with almost complete relief from pain for 298. The arc of movement had increased from a mean of 85.7 °pre-operatively to 95.1 ° post-operatively, and to 98.1 °at the latest follow-up. Spot welds around the humeral stem suggesting solid osseous integration were often seen in the elbows with cementless fixation of the porous humeral stem. At the latest follow-up, implants were removed due to infection in 3 elbows. Twenty-five elbows required ulnar component revision due to loosening of the all-polyethylene component. Two elbows required ulnar component revision due to loosening of the metal-backed component. Seven elbows required humeral component revision due to loosening of the humeral components. One elbow required revision due to dislocation. A survival analysis with revision or removal of one or both components as the end point was performed according to the Kaplan and Meier method. The overall survival rate of the prosthesis was 75.2% at 19 years. The survival of 87.0% in the metal-backed group was higher than the 74.3% in the all-polyethylene group. Loosening of the all-polyethylene ulnar component was the main reason for deterioration in the long-term outcome.

We conclude that the long-term results of the Kudo type-5 total elbow arthroplasty is acceptable and cemented fixation of metal-backed ulnar component had better long-term survival than the all-polyethylene component.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_9 | Pages 100 - 100
1 May 2016
Onishi H Tsukamoto M Okabe S Mori T Uchida S Murata Y Moridera K Hirano F Ikei D Kamegawa S Akinori S
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Introduction

The purpose of this study was to introduce our perioperative prophylaxis method for infection and clarify surgical site infection rate in our patients performed total hip arthroplasty (THA).

Method

Two hundred and eighty four THA (including revision 18 cases) performed by single surgeon between Oct. 2007 and Jan. 2013 were evaluated. The mean age of patients was 65.7 years old. The male to female ratio was 46 to 238. BMI was 23.6. Ninety patients (32%) were compromised host suffering from diabetes mellitus, rheumatoid arthritis, autoimmune disease, history of malignant tumor, hemodialysis or skin disease at surgical site respectively. At preoperative period, we checked decayed tooth, alveolar pyorrhea, hemorrhoids, and leg skin condition. In addition, we examined culture of nasal cavity. At the day of surgery, patient took a shower just before entering surgical room. All of THA was performed in clean room NASA class 100. Surgeons and assistant nurse put on nonwoven fabric gown, space suit and double rubber gloves. We wiped surgical site leg by gauze impregnated by 0.5% chlorhexidine alchohol to eliminate skin bacteria twice just before surgeons scrubbing hands. Surgical site was covered by povidone iodine containing drape. Surgeons or nurse changed gloves when glove was broken at each time. We cleaned surgical field by pulse washer whenever necessary. We did not use drain except for 5 revision THAs. Regarding to prophylactic antibiotics usage, we administered cefcapene pivoxil orally the day before surgery. Drip infusion antibiotics (PIPC: until Oct. 2008, CEZ: after Oct. 2008) was administered at the period of 30 min. before surgery and 4 hours after surgery in case of prolonged surgical time (4 hours >). Skin closure was performed by staple and covered by gauze until May 2010. After that, we used surgical tape and transparent water proof sheet. After finishing surgery, antibiotic was administered 8 hours interval at surgery day and 12 hours interval for additional two days. In case multi-drug resistant bacteria (MRSA, MRSE) was positive in nasal culture, we applied mupirocin ointment to nasal cavity for 3 days before surgery and administered vancomycin (from Aug. 2011) or linezolid (from 2012) for prophylactic antibiotics in perioperative period.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_3 | Pages 24 - 24
1 Jan 2016
Masuda K Iwasawa M Ogihara S Takamure H Ohashi S Mori T
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Objective

The aim of this study was to investigate the clinical results of treatment for patients with periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) in our department.

Patients and Methods

Between April 2004 and March 2014, 9 patients with rheumatoid arthritis (RA) and 6 patients with osteoarthritis (OA) were identified as PJI following TKA and treated in our hospital. We investigated retrospectively the data of each patient, including the clinical background and the peri-operative data as well as the outcome at final follow-up.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 518 - 518
1 Oct 2010
Hirano F Fujii H Mori T Nakamura T Ohnishi H Okabe S Tanaka S Tsurukami H Uchida S
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Purpose: There is no report concerning about long-term comparison result of high placed cementless cup stability with or without screws for developmental dysplasia of the hip. The aim of this study was to ascertain whether or not there are any differences in high placed cementless cup stability with or without screws at the mean 10-year (6–14) follow-up period.

Method: We divided 109 hip-cases who underwent identical cementless total hip arthoplasty system (Mallory – Head : Biomet Inc.) to two groups: 57 cups with screw (screw group) and 52 cups without screw (no screw group). No case in both group underwent bulk bone graft for acetabular roof. Radiographic signs of cup instability were defined as the development of radiolucent line (> 2mm) or migration (> 4mm). Degree of subluxation by Crowe classification, cup size and cup abduction angle were also measured.

Results: In both groups, there was no significant difference in terms of degree of subluxation (each grade’s %) (screw vs no screw = I (68, 73), II (21, 25), III (11,0), IV (0, 2)), age (yrs) (58, 60), cup size (mm) (46, 47) and cup abduction angle (49, 47). In screw group, one case was revised by replacing only polyethylene insert due to excessive ware. No case in both group showed any sign of component instability.

Conclusion: High placed Mallory-Head type cementless cup without screws showed stable radiographic fixation as well as cup with screws at mean 10 years follow-up period.


The Journal of Bone & Joint Surgery British Volume
Vol. 88-B, Issue 7 | Pages 920 - 924
1 Jul 2006
Mori T Kudo H Iwano K Juji T

We studied 11 patients (14 elbows) with gross rheumatoid deformity of the elbow, treated by total arthroplasty using the Kudo type-5 unlinked prosthesis, and who were evaluated between five and 11 years after operation. Massive bone defects were augmented by autogenous bone grafts. There were no major complications such as infection, subluxation or loosening. In most elbows relief from pain and stability were achieved. The results, according to the Mayo Elbow Performance Score, were excellent in eight, good in five and fair in one. In most elbows there was minimal or no resorption of the grafted bone. There were no radiolucent lines around the stems of the cementless components. This study shows that even highly unstable rheumatoid elbows can be replaced successfully using an unlinked prosthesis, with augmentation by grafting for major defects of bone.


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_II | Pages 211 - 211
1 May 2006
Masuda K Mori T Juji T Marutani R Hirose T
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Objective: The aim of this study was to evaluate the safety and efficacy of sequential bilateral total knee arthroplasty (TKA) for patients with rheumatoid arthritis (RA), in comparison with staged bilateral and unilateral TKA.

Patients and Methods: Between July 2000 and June 2005, 340 TKA were performed in our department. We investigated retrospectively the clinical data of each patient, including the peri-operative data such as the surgical time, the amount of haemorrhage and postoperative adverse events. We also examined the clinical outcome before and after bilateral TKA by using the Japanese Orthopaedic Association (JOA) evaluation chart of knee joint function (JOA score).

Results: We have done sequential bilateral TKA for 60 knees of 30 patients (group A), staged bilateral TKA for 26 knees of 13 patients (group B) and unilateral TKA for 254 knees (group C). Before TKA, the mean JOA score were 44.9, 40.1, 46.4 points, and the mean range of motion of affected knees were 14.6–113.6°, 27.9–89.6°, 14.1–116.9° in group A, B and C, respectively, indicating that group B included more severe cases. Whereas the mean surgical time were 136.4, 158.4, 154.3 minutes, the mean amount of peri-operative haemorrhage were 414.6, 273.4, 277.7 ml in group A, B and C, respectively. Although we experienced 1 case with symptomatic pulmonary embolism in group A, which was successfully treated, there was none of cases with death within 1 month of surgery or early-phase infection. The JOA score at final follow-up (the mean follow-up period was 1 year and 8 months) were 91.1 and 86.9 points in group A and B, respectively, showing good results in both groups.

Conclusion: In short-term data, sequential bilateral TKA was successfully performed and beneficial approach to patients with RA. The intensive pre- and post-operative management could be essential for good clinical outcome. Further improvement should be needed to perform this procedure more safely and prevent complications, especially serious cardiopulmonary events.