Ultrasonic cement removal in revision arthroplasty

Efficient and safe cement removal is critical in revision arthroplasty. Conventional manual cement removal by hand or power-driven instruments can be time-consuming, require osteotomy, and be associated with complications such as cortical perforation, fracture, or bone loss. Ultrasonic devices offer an alternative method of cement removal by converting mechanical vibrations into thermal energy, liquefying the cement. This facilitates selective cement removal, preserves bone, decreases cortical perforation risk, and eliminates the need for osteotomy. However, potential for thermal injury exists. Ultrasound basic science, mechanism of action, and clinical applications with specific emphasis on methods to limit excessive heat generation are reviewed.     

Computer-aided reconstruction of hip joint in revision arthroplasty

Geometric revision reconstruction of the hip joint of a female patient is presented. Because of extensive bone resorption and strong bone obstruction, we decided to employ a custom–made prosthesis not only in the pelvis but also in the femur. The custom prosthesis design and manufacturing processes were carried out with the aid of computed tomography (CT), a system of tomographic image processing, a computer–aided design (CAD) system and a computer–aided manufacturing (CAM) system. The process included tomographic measurements of the patient’s hip joint, conversion of the CT images, geometrical modelling of the femur and pelvis in the CAD system, prostheses design, virtual simulation of the reconstructed acetabulum, determination of prosthesis matching, and manufacturing on a CNC machine. The outcome of this engineering process was a total hip arthroplasty (THA) surgical operation.     

The role of intraoperative Gram stain in revision total joint arthroplasty.

The ability to identify intraoperatively patients with an infected prosthesis at the time of a revision procedure assists the surgeon in selecting appropriate management. The results of 413 intraoperative Gram stains were compared with the results of operative cultures, permanent histology, and the surgeon's intraoperative assessment to determine the ability of Gram stains to identify periprosthetic infection. Gram staining correctly identified the presence of infection in 10 of the 68 cases that met study criteria for infection (sensitivity of 14.7%). Four false-positive Gram stains were encountered. Intraoperative Gram stains do not have adequate sensitivity to be helpful in identifying periprosthetic infection and should not be performed on a routine basis. They may be helpful, however, in cases in which gross purulence is encountered to assist in the selection of initial antibiotic therapy. The use of intraoperative Gram staining alone is inadequate for ruling out infection at the time of revision total joint arthroplasty.     

The fate of femoral windows in revision joint arthroplasty

We retrospectively reviewed the radiographs of twenty patients in whom a window in the femoral cortex had been created to facilitate revision of a failed total hip replacement with a non-cemented prosthesis, to determine if the window had healed and, if so, how long it had taken. All but three windows showed clear evidence of healing three months postoperatively. At six months, only two windows remained radiographically visible, and at eight months, all of the windows had healed. We concluded that when the section of cortical bone that is removed to create the window is replaced with an uncemented femoral component, the window heals by bone within three to eight months.     

Intraoperative frozen section analysis in revision total joint arthroplasty

A prospective study of the sensitivity, specificity, and predictive values for frozen sections against cultures obtained at the time of revision total joint replacement was done. One hundred twenty-one revision total joint replacements were done in 92 men and 29 women. A positive frozen section with more than 10 polymorphonuclear leukocytes per high power field was compared with the intraoperative cultures. Twenty-one patients who had revision surgery had greater than 10 polymorphonuclear leukocytes per high power field. Of these, 14 patients had positive cultures. The remaining 100 patients had less than 10 polymorphonuclear leukocytes per high power field, but seven had positive cultures. Statistical analysis of frozen sections for all total joint arthroplasties revealed a 67% sensitivity, 93% specificity, 67% positive predictive value, and 93% negative predictive value. Analysis of frozen sections for total hip arthroplasties revealed a 45% sensitivity, 92% specificity, 55% positive predictive value, and 88% negative predictive value. Analysis for total knee arthroplasties revealed 100% sensitivity, 96% specificity, 82% positive predictive value, and 100% negative predictive value. Comparisons of sensitivity, positive predictive value, and negative predictive value between total knee arthroplasty and total hip arthroplasty were significant. The results indicate that the use of intraoperative frozen section analysis with greater than 10 polymorphonuclear leukocytes per high power field as an indication of infection lacks the positive predictive value and sensitivity for accurate determination of prosthetic infection at the time of revision total hip arthroplasty. Frozen sections have an acceptable sensitivity and positive predictive value in total knee arthroplasty. The results of the current study show the limitation of using frozen sections as a diagnostic test for infection in revision total hip arthroplasty.     

人工关节置换术后感染的Ⅱ期翻修术

随着材料技术和加工技术的进步 ,目前人工全髋关节置换术后感染发生率已降到 1%以下〔1〕。临床上治疗以Ⅱ期翻修术较常用 ,现就有关内容综述如下。1　人工关节置换术后感染的发生人工关节置换术后感染发生与否取决于细菌数量、毒力及机体抵抗力。细菌以凝固酶阴性表皮葡萄球菌和金黄色葡萄球菌多见 ,两者所占比例超过5 0 % 〔2〕,革兰阳性杆菌、β 溶血性链球菌、肠球菌和厌氧菌次之〔3〕,布氏杆菌、真菌等极少见〔4〕。术中细菌残留、术后细菌经血液播散是感染发生的基本途径〔5〕。据临床统计 ,手术室空气中细菌坠落污染是最主要来源 ,占…     

Cementless acetabular revision arthroplasty.

OBJECTIVE: To evaluate the effects of clinical factors on outcome after acetabular revision with a cementless beaded cup. DESIGN: Retrospective case series. SETTING: Tertiary care referral centre. PATIENTS: Forty-one patients who underwent acetabular revision with a cementless cup were followed up for a mean of 3.4 years. INTERVENTIONS: Acetabular revision with a beaded cementless cup in all patients. A morcellized allograft was used in 10 patients. OUTCOME MEASURES: A modified Harris hip score (range of motion measurement omitted), the SF-36 health survey, and the Western Ontario McMaster (WOMAC) osteoarthritis index. Multivariate analysis was used to evaluate the effects of age, gender, morcellized allografting, time to revision from the previous operation, acetabular screw fixation and concurrent femoral revision on outcome. RESULTS: Gender accounted for a significant portion of the variation seen in the SF-36 physical component scores (r = 0.36, p = 0.02), with women tending to have worse results. Increasing age was associated with lower WOMAC index function scores (r = 0.36, p = 0.03), whereas concurrent femoral revision tended to have a positive effect on WOMAC index function (r = 0.39, p = 0.01). None of the potential clinical predictors had any significant effect on the SF-36 mental component scores, or WOMAC index pain and stiffness scores. CONCLUSIONS: In cementless acetabular revision arthroplasty, physical function, as measured by generic and limb-specific scales, may be affected by gender, age and the presence of a concurrent femoral revision. Time to revision from the previous operation, morcellized allografting and screw fixation of the acetabulum did not affect outcomes. This information may provide some prognostic value for patients' expectations.     

Shear properties of bilaminar polymethylmethacrylate cement mantles in revision hip joint arthroplasty

Although cement-within-cement revision arthroplasty minimizes the complications associated with removal of secure PMMA, failure at the interfacial region between new and old cement mantles remains a theoretical concern. This article assesses the variability in shear properties of bilaminar cement mantles related to duration of postcure and the use of antibiotic cements. Bilaminar cement mantles were 15% to 20% weaker than uniform mantles (P < .001) and demonstrated variability in shear strength related to duration of postcure of the freshly applied cement (P < .001). The use of Antibiotic Simplex did not significantly influence interfacial cement adhesion (P = .52). Interfacial adhesion by mechanisms other than mechanical interlock plays a significant role in the bond formed between new and old PMMA cements, with an important contribution by diffusion-based molecular interdigitation. In the presence of a secure cement-bone interface, we recommend cement-within-cement revision techniques in suitable patients.     

Ionogran in revision arthroplasty

Glass ionomer cement (Ionocem) was developed for use in bone surgery and is reported to be notably biocompatible. Between 1991 and 1994 we performed revision operations for aseptic loosening of arthroplasties of the hip on 45 patients using this material in its granulate form (Ionogran) mixed with homologous bone as a bone substitute. Of these 45 patients, 42 were followed up for a mean of 42 months. Early reloosening of the acetabular component has occurred in ten after a mean of 30 months. Histological examination showed large deposits of aluminium in the adjacent connective tissue and bone. Osteoblastic function and bone mineralisation were clearly inhibited. The serum levels of aluminium were also increased. The toxic damage at the bone interface caused by high local levels of aluminium must be seen as an important factor in the high rate of early reloosening. Our findings cast doubt on the biocompatibility of this material and we do not recommend continuation of its further use in orthopaedic surgery.     

Results of revision metacarpophalangeal joint surgery in rheumatoid patients following previous silicone arthroplasty

PURPOSE: Primary silicone metacarpophalangeal (MCP) joint arthroplasties have good results that deteriorate with time. The purpose of this study was to assess indications, patient satisfaction, and clinical and radiographic results following revision surgery in rheumatoid patients who had previously undergone silicone MCP arthroplasty. METHODS: Twenty hands in 18 patients (62 implants) had revision silicone MCP arthroplasties between 1986 and 2005 and had a greater than 1-year follow-up period (mean 5 y). A retrospective chart review was performed to collect preoperative and intraoperative data. Patients were then re-examined and administered a questionnaire addressing subjective outcome and satisfaction. RESULTS: Intraoperatively, 76% of the implants were fractured. Thirteen of 17 synovial biopsies revealed giant cell foreign body reaction. Preoperatively, the average arc of motion was from 16 degrees to 50 degrees , and ulnar drift was 24 degrees . Postoperatively, the average arc of motion was from 20 degrees to 54 degrees , and ulnar drift was 13 degrees . X-rays of 14 hands revealed that 15 of 44 revised implants had fractured. Sixteen patients (18 hands) were available to complete questionnaires. Twelve patients (14 hands) were satisfied and 3 were dissatisfied. Five of 16 patients would not have the revision again. These patients had worse average postoperative ulnar drift (30 degrees vs 9 degrees ) than the other 11 patients. All patients except one who had preoperative pain had at least moderate pain relief, and of the 6 patients who had revision surgery because of pain, 5 were satisfied. CONCLUSIONS: Revision silicone arthroplasty provides excellent pain relief, and the majority of patients were pleased with their results. Objective results, however, were generally poor. Soft tissue reconstruction is more difficult to achieve than the primary procedure, as evidenced by minimal improvement in ulnar drift, a high rate of implant fracture, and no change in arc of motion. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.     

二期翻修术治疗关节置换术后感染中抗生素使用的策略

[目的]探讨采用二期翻修术治疗关节置换术后感染过程中抗生素使用的有效方法。[方法]采用抗生素骨水泥占位器进行二期翻修治疗了15例髋关节置换术后感染的患者和10例膝关节置换术后感染的患者。其中9例髋关节置换术后感染患者与6例膝关节置换术后感染的患者在一期清创术后及二期翻修术后常规静脉使用抗生素6周，再口服抗生素2个月；另外6例髋关节置换术后感染患者与4例膝关节置换术后感染患者一期清创置入假体后及二期翻修术后只静脉使用抗生素3周，口服抗生素6周：术后定期随访，检测血沉及CRP，应用X线片与Harris评分与HSS评分进行评价。[结果]平均随访时间20．2个月（15～24个月）。两组患者的Harris评分与HSS评分无明显差异，长期使用抗生素组的患者满意率为93．3％，短期使用抗生素组的患者满意率为90％。在最后随访两组均没有感染复发的病例。[结论]在使用抗生素骨水泥占位器的条件下，在二期翻修治疗关节置换术后感染中短期使用抗生素是安全可靠的。     

Component removal in revision total hip arthroplasty.

One of the primary steps in revision hip arthroplasty is the extraction of retained components before surgical reconstruction. In revision arthroplasty, the removal of well-fixed components and cement can be extremely demanding, time consuming, and damaging to the remaining host bone. The aims of the current study were to examine the numerous operative techniques used during extraction of acetabular and femoral components and review the results of revision hip arthroplasty after cementless component removal. A review of 157 acetabular components and 113 femoral components removed from 219 patients during hip revision arthroplasty between 1985 and 2000 was done. The average age of the patients was 64.3 years. The average followup was 5 years (range, 0.7-12.5 years). An extended proximal femoral osteotomy was done in 37 (33%) of the femoral revisions. There were 14 (5%) acetabular failures for which the patients required reoperation. There were no femoral rerevisions. Complications included dislocation (6% after acetabular revision and 9% after femoral revision), infection (6%), femoral fracture (6%), hematoma (3.5%), acetabular fixation failure (2.5%), and femoral osteolysis (1%). The removal of cemented and well-fixed porous-coated implants can be done with adequate preoperative planning and a thorough knowledge of numerous implant removal techniques.     

关节置换外科新技术:实践与评估

近年来,大量的新技术与传统技术的改良被广泛地引入关节置换外科领域,正是由于新技术的开展和对传统技术的改进,才使得关节外科在全球范围内获得了持续发展。本期“人工关节置换”专题中发表的论文从一个侧面反映了国内同道在应用新技术和改进传统技术方面的努力。