The value of computed tomography based navigation in revision total hip arthroplasty

Purpose

This study investigates the accuracy of a computed tomography (CT)-based navigation system for accurate acetabular component placement during revision total hip arthroplasty (THA).

Methods

We performed a retrospective review of 30 hips in 26 patients who underwent cementless revision THA using a CT-based navigation system; the control group consisted of 25 hips in 25 patients who underwent cementless primary THA using the same system. We analysed the deviation of anteversion and inclination angles among the pre-operative plan, intra-operative records from the navigation system and data from postoperative CT scans.

Results

There were no significant differences between groups (P < 0.05) in terms of mean deviation between pre-operative planning and postoperative measurements or between intraoperative records and postoperative measurements.

Conclusion

CT-based navigation in revision THA is a useful tool that enables the surgeon to implant the acetabular component at the precise angle determined in pre-operative planning.     

Infection after total knee arthroplasty

The aim of our study was to determine the current incidence and outcome of infected total knee arthroplasty (TKA) in our unit comparing them with our earlier audit in 1986, which had revealed infection rates of 4.4% after 471 primary TKAs and 15% after 23 revision TKAs at a mean follow-up of 2.8 years. In the interim we introduced stringent antibiotic prophylaxis, and the routine use of occlusive clothing within vertical laminar flow theatres and 0.05% chlorhexidine lavage during arthroplasty surgery. We followed up 931 primary TKAs and 69 revision TKAs for a mean of 6.5 years (5 to 8). Patients were traced by postal questionnaire, telephone interview or examination of case notes of the deceased. Nine (1%) of the patients who underwent primary TKA, and four (5.8%) of those who underwent revision TKA developed deep infection. Two of nine patients (22.2%) who developed infection after primary TKA were successfully treated without further surgery. All four of the patients who had infection after revision TKA had a poor outcome with one amputation, one chronic discharging sinus and two arthrodeses. Patients who underwent an arthrodesis had comparable Oxford knee scores to those who underwent a two-stage revision. Although infection rates have declined with the introduction of prophylactic measures, and more patients are undergoing TKA, the outcome of infected TKA has improved very little.     

Intraoperative Medial Pivot Affects Deep Knee Flexion Angle and Patient-Reported Outcomes After Total Knee Arthroplasty

The aim of this study was to evaluate the relationship between clinical results including patient-reported outcomes and intraoperative knee kinematic patterns after total knee arthroplasty (TKA). A cross-sectional survey of forty consecutive medial osteoarthritis patients who had a primary TKA using a CT-based navigation system was conducted. Subjects were divided into two groups based on intraoperative kinematic patterns: a medial pivot group (n = 20) and a non-medial pivot group (n = 20). Subjective outcomes with the new Knee Society Score and clinical outcomes were evaluated. The functional activities, patient satisfaction and the knee flexion angle of the medial pivot group were significantly better than those of the non-medial pivot group. An intraoperative medial pivot pattern positively influences deep knee flexion and patient-reported outcomes.     

一期翻修治疗全膝关节置换术后假体周围慢性感染的实验研究

 目的 通过动物实验探讨一期翻修治疗耐甲氧西林金黄色葡萄球菌所致假体周围慢性感染的疗效。方法 48只新西兰兔行右膝关节置换,术后 4周接种耐甲氧西林金黄色葡萄球菌建立假体周围感染模型。接种 4周后,随机分为两组院实验组一期翻修,对照组行二期翻修第一步抗生素骨水泥填充术。监测置换前,翻修前,翻修后 1、3、5、7天和 2、4、6、12周的 C反应蛋白和红细胞沉降率。翻修后 12周处死,膝关节取样进行细菌培养。培养结果阳性为再感染,阴性为治愈。结果 5只实验动物出组。实验组再感染率为 22.7%(5/22),对照组再感染率为 14.3%(3/21), 两组差异无统计学意义(χ²= 0.102,P=0.750)。翻修后两组 C反应蛋白均升高,第 3天达峰值,第 4周恢复至初次置换前水平,两组差异无统计学意义(F=0.157,P=0.694)。翻修后两组红细胞沉降率均升高,第 5天达峰值,第 12周恢复至初次置换前水平,两组差异无统计学意义(F=0.936,P=0.339)。结论 在明确菌种及其抗菌谱的前提下,治疗由高毒力细菌引起的膝关节假体周围慢性感染,一期翻修的近期疗效与二期翻修无差异。     

Osteotomy and Unicompartmental Knee Arthroplasty Converted to Total Knee Arthroplasty : Data From the New Zealand Joint Registry

We reviewed the revision rate and functional outcome of all patients who had a total knee arthroplasty (TKA) after an osteotomy or unicompartmental knee arthroplasty (UKA) on the New Zealand Joint Registry. We used these data to compare the results with primary TKA scores, including comparison of age-matched subgroups. There were 711 patients who had undergone TKA as salvage for a failed osteotomy with a revision rate of 1.33 per 100 component years and a mean 6-month Oxford Knee Score (OKS) of 36.9. There were 205 patients who had a failed UKA converted to TKA with a revision rate of 1.97 per 100 component years and a mean OKS of 29.1. The revision rates of TKA for both failed osteotomy and failed UKA were significantly poorer than after primary TKA (0.48 per 100 component years). The mean OKS after revision of a UKA was significantly poorer than both primary TKA and TKA for a failed osteotomy. There was no significant difference in mean OKS between primary TKA and TKA for a failed osteotomy, even among patients younger than 65 years. Revision of a failed osteotomy to a TKA has improved functional results compared with revision of a failed UKA. However, both yield poorer survivorship rates compared with primary TKA.     

A large metallic cyst caused by wear particles after total knee arthroplasty

Introduction A symptomatic cyst is an uncommon complication after total knee arthroplasty (TKA). We present a case of a 77-year-old woman with a large cyst in the right knee caused by metal wear debris from the failure of a Miller-Galante I TKA performed 13 years earlier. Case presentation The patient was treated with a two-stage operation including revision of the TKA followed by excision of the cyst, because there was a direct communication between the joint cavity and the cyst, and because the patient reported pain corresponding to the cystic area after revision. The patient was pain-free and had a satisfactory result 17 months after the second operation, without recurrence of cyst formation. Conclusion We recommend two-stage surgery in which the first-stage is correction of the intra-articular pathology with revision TKA and the second-stage is excision of the cyst.     

Navigation in total-knee arthroplasty: CT-based implantation compared with the conventional technique

Background Exact axial limb alignment in total-knee arthroplasty (TKA) is important for a successful outcome. We evaluated the efficiency of computer-assisted implantation in TKA and compared it with the classical surgeon-controlled technique. Patients and methods We implanted 100 TKA using either the computer-assisted technique (50) or the conventional approach (50). There were no significant differences between the groups regarding the preoperative leg deformity. Accuracy of implantation was determined in postoperative long-leg coronal and lateral radiographs. Results A postoperative leg axis between 3 degrees varus and 3 degrees valgus was achieved in 46 patients in the group with computer-assisted implantation and 36 patients in the control group (p=0.01). A significant difference was also seen for the femoral component alignment in frontal plane. No complications influencing the clinical outcome were observed. Interpretation A CT-based navigation system improves the accuracy of TKA, but higher costs and time-consuming planning will mean that its usage is limited to special cases. Additional tools such as ligament balancing, which are presently only available with the CT-free software module, require to be added to the CT-based system.     

Weight Gain After Primary Total Knee Arthroplasty Is Associated With Accelerated Time to Revision for Aseptic Loosening

BackgroundObesity is a major health problem worldwide and is associated with complications after total knee arthroplasty (TKA). It remains unknown whether a change in body mass index (BMI) after primary TKA affects the reasons for revision TKA or the time to revision TKA.MethodsA total of 160 primary TKAs referred to an academic tertiary center for revision TKA were retrospectively stratified according to change in BMI from the time of their primary TKA to revision TKA. The association between change in BMI and time to revision was also analyzed according to indication for revision of TKA using Pearson's chi-square test.ResultsThe mean change in BMI from primary to revision TKA was 0.82 ± 3.5 kg/m². Maintaining a stable weight after primary TKA was protective against late revision TKA for any reason (P = .004). Patients who failed to reduce their BMI were revised for aseptic loosening earlier, at less than 5 years (P = .020), whereas those who reduced their BMI were revised later, at over 10 years (P = .004).ConclusionMaintaining weight after primary TKA is protective against later revision TKA for any reason but failure to reduce weight after primary TKA is a risk factor for early revision TKA for aseptic loosening and osteolysis. Orthopedic surgeons should recommend against weight gain after primary TKA to reduce the risk of an earlier revision TKA in the event that a revision TKA is indicated.     

Navigation in total-knee arthroplastyCT-based implantation compared with the conventional technique

Background?Exact axial limb alignment in total-knee arthroplasty (TKA) is important for a successful outcome. We evaluated the efficiency of computer-assisted implantation in TKA and compared it with the classical surgeon-controlled technique. Patients and methods?We implanted 100 TKA using either the computer-assisted technique (50) or the conventional approach (50). There were no significant differences between the groups regarding the preoperative leg deformity. Accuracy of implantation was determined in postoperative long-leg coronal and lateral radiographs. Results?A postoperative leg axis between 3° varus and 3° valgus was achieved in 46 patients in the group with computer-assisted implantation and 36 patients in the control group (p=0.01). A significant difference was also seen for the femoral component alignment in frontal plane. No complications influencing the clinical outcome were observed. Interpretation?A CT-based navigation system improves the accuracy of TKA, but higher costs and time-consuming planning will mean that its usage is limited to special cases. Additional tools such as ligament balancing, which are presently only available with the CT-free software module, require to be added to the CT-based system.     

Novel computer-assisted method for revision arthroplasty of the knee

AIM: To introduce the navigation system of software and instruments designed specifically for revision total knee arthroplasty (TKA).METHODS: We present an imageless navigation system for revision TKA, with optical point and tracker identification to assess kinematic and anatomical landmarks. The system automatically positions the cutting guides with a motorized cutting unit. The cutting unit is placed on the distal femur with a femoral clamp and acts as a rigid body and the base for all femoral cuts. The surgical technique for using the navigation system for revision TKA is based on the technique used in primary TKA. However, there are some important differences. The most notable are: (1) differences in estimation of the position of the primary implant relative to the bone and the mechanical axes; (2) the specific possibilities the revision navigation software offers in terms of optimal joint level positioning; and (3) the suggested “best fit” position, in which the clock position, stem position and offset, femoral component size, and mediolateral position of the femoral component are taken into account to find the optimal femoral component position. We assessed the surgical technique, and accompanying software procedural steps, of the system, identifying any advantages or disadvantages that they present.RESULTS: The system aims to visualize critical steps of the procedure and is intended as a tool to support the surgeon in surgical decision-making. Combining a computer-assisted cutting device with navigation makes it possible to carry out precise cuts without pinning. Furthermore, the femoral clamp provides a stable fixation mechanism for the motorized cutting unit. A stable clamp is paramount in the presence of periarticular bony defects. The system allows the position of the primary implant relative to the bone and mechanical axes to be estimated, at which point any malalignments can be corrected. It also offers an optimal joint level position for implantation, and suggests a “best fit” position, in which the clock position, stem position and offset, femoral component size, and mediolateral position of the femoral component are considered. The surgeon can therefore make decisions intraoperatively to maximise alignment and, hence, outcomes. Based on the intraoperative findings of joint stability, the surgeon can modify the preoperative plan and switch from a constrained condylar system to a hinged version, or vice versa.CONCLUSION: The system is flexible and easy to learn and allows improvements in workflow during TKA.     

应用抗生素骨水泥间隔体二期翻修治疗人工全膝关节置换术后迟发感染

目的探讨应用抗生素骨水泥间隔体二期翻修治疗人工全膝关节置换术后迟发感染的临床疗效。方法 2007年1月-2009年12月,收治23例(23膝)人工全膝关节置换术后迟发感染患者。男15例,女8例;年龄43～75岁,平均65.2岁。置换术后至出现感染时间为13～52个月,平均17.3个月;发生感染至入院翻修时间为15 d～7个月,平均2.1个月。一期清创、取出假体,植入含庆大霉素抗生素骨水泥间隔体;8～10周感染控制后二期植入假体。分别采用美国特种外科医院(HSS)评分及膝关节学会评分系统(KSS)评价翻修前后患膝功能,并统计总体感染控制率。结果术后患者切口均Ⅰ期愈合。2例二期翻修术后发生再感染,余21例感染控制,总体感染控制率91.3%。患者均获随访,随访时间2～5年,平均3.6年。HSS评分由术前(60.6±9.8)分提高至末次随访时(82.3±7.4)分,KSS评分由术前(110.7±9.6)分提高至末次随访时(134.0±10.5)分,手术前后比较差异均有统计学意义(P<0.01)。X线片复查示假体位置良好,无松动、断裂、假体周围透亮影等异常表现。结论应用抗生素骨水泥间隔体二期翻修能有效控制人工全膝关节置换术后迟发感染,并能较好恢复患膝功能。     

Bone Loss During Revision of Unicompartmental to Total Knee Arthroplasty : An Analysis of Implanted Polyethylene Thickness From the National Joint Registry Data

Using the National Joint Registry (UK) database, we compared the thickness of polyethylene (PE) and the level of constraint used during primary total knee arthroplasty (TKA) versus the revision of unicondylar knee arthroplasty (UKA) to TKA. A total of 251,803 TKA procedures and 374 revision UKA–TKA procedures between 2003 and 2009 were reviewed. The commonest PE size used in TKA was 10 mm, compared to 12.79 mm in the revision group. The use of constrained knee implant was required in 2.15% of primary TKA and 4.19% of UKA to TKA revisions. The revision of UKA to TKA is a more complex procedure compared to primary TKA, with a higher incidence of using constrained implants and thicker PE inserts. These findings may be useful for surgeons in their decision making.     

Early patient outcomes after primary and revision total knee arthroplasty. A prospective study

There has been speculation as to how the outcome of revision total knee arthroplasty (TKA) compares with that of primary TKA. We have collected data prospectively from patients operated on by one surgeon using one prosthesis in each group. One hundred patients underwent primary TKA and 60 revision TKA. They completed SF-12 and WOMAC questionnaires before and at six and 12 months after operation. The improvements in the SF-12 physical scores and WOMAC pain, stiffness and function scores in both primary and revision TKA patients were highly statistically significant at six months. There was no statistically significant difference in the size of the improvement in the SF-12 physical and WOMAC pain, stiffness and function scores between the primary and revision patients at six months after surgery. The SF-12 mental scores of patients in both groups showed no statistically significant difference after surgery at the six- and 12-month assessments. Our findings show that primary and revision TKA lead to a comparable improvement in patient-perceived outcomes of physical variables in both generic and disease-specific health measures at follow-up at one year.     

CT-based and CT-free navigation in total knee arthroplasty--a prospective comparative study with respects to clinical and radiological results

AIM: Optimal component position in all planes and well-balanced soft tissues are factors for clinical outcome and survival time after total knee arthroplasty (TKA). With regard to clinical and radiological parameters, a comparative study between CT-based and CT-free navigation techniques was performed. METHOD: In this prospective study 44 patients (44 surgeries) were enrolled. One half of the surgeries were performed using a CT-based navigation system (group A), the other half using a CT-free system (group B). Pre-operatively and three months post-operatively the patients were physically examined (Insall score, step test, anterior knee pain, subjective feeling of instability and patient satisfaction) and limb alignment was measured by radiographs (mechanical axis, tibial slope, lateral distal femur angle [LDFA], medial proximal tibia angle [MPTA]). The tolerable inaccuracy range for all radiological measurements was +/- 3 degrees. RESULTS: The radiological measurements showed a high accuracy but no significant differences (patients within tolerable range group A/B: mechanical axis 85.7/81.0 %, tibial slope 95.2/90.5 %, LDFA 100/95.2 %, MPTA 90.5/95.2 %). For physical parameters we found a better ligament balancing in group B. CONCLUSION: The CT-based module has an optimal planning procedure but costs more. The CT-free system provides equal radiological results and the availability of a useful ligament balancing module.     

Primary Versus Secondary Distal Femoral Arthroplasty for Treatment of Total Knee Arthroplasty Periprosthetic Femur Fractures

Current methods of fixing periprosthetic fractures after total knee arthroplasty (TKA) are variable, and include open reduction and internal fixation (ORIF) via plating, retrograde nailing, or revision using standard revision TKA components or a distal femoral arthroplasty (DFA). The purpose of this study is to compare patients who failed plating techniques requiring subsequent revision to DFA to patients who underwent primary DFA. Of the 13 patients (9.2%) who failed primary ORIF, causes included nonunion (53.8%), infection (30.8%), loosening (7.7%), and refracture (7.7%). There were significantly more surgical procedures for ORIF revision to DFA compared to primary DFA. Complications for patients who underwent primary reconstruction with DFAs included extensor mechanism disruption (8.3%), infection (5.6%), and dislocation (2.8%). Primary reconstruction via ORIF is beneficial for preserving bone stock, but primary DFA may be preferred in osteopenic patients, or those at high risk for nonunion.     

Outcomes of Primary Total Joint Arthroplasty After Lung Transplantation

Lung transplantation is increasingly common with improving survival rates. Post-transplant patients can be expected to seek total hip (THA) and knee arthroplasty (TKA) to improve their quality of life. Outcomes of 20 primary total joint arthroplasties (15 THA, 5 TKA) in 14 patients with lung transplantation were reviewed. Clinical follow-up time averaged 27.5 and 42.8 months for THA and TKA respectively. Arthroplasty indications included osteonecrosis, osteoarthritis, and fracture. All patients subjectively reported good or excellent outcomes with a final average Harris Hip Score of 88.7, Knee Society objective and functional score of 92.0. There were 4 minor and 1 major acute perioperative complications. 1 late TKA infection was successfully treated with two-stage revision. The mortality rate was 28.5% (4/14 patients) at an average 20.6 months following but unrelated to arthroplasty. Overall, total joint arthroplasty can be safely performed and provide good functional outcomes in lung transplant recipients.     

Comparison of the hospital cost of primary and revision total knee arthroplasty after cost containment

Revision total knee arthroplasty (TKA) consumes more time, more work, and more supplies than primary TKA. This study compared the hospital cost of primary and revision TKA after the introduction of cost-containment programs (implant standardization, clinical pathway, and competitive bid implant purchasing) at our hospital. Hospital financial records of 207 primary unilateral TKA operations and 32 revision TKA operations performed from October 1993 through September 1995 were analyzed. A cost-accounting system provided actual hospital cost data for each procedure. Accurate calculation of hospital income or loss was determined for all 239 procedures. The average hospital length of stay was 4.7 days for primary unilateral TKA and 5.1 days for revision TKA. There were 26 three-component revision operations and 6 one- or two-component revision operations. The average hospital cost was $10,421 for primary TKA and $11,906 for revision TKA. The average net hospital income (hospital revenue - hospital expense) was $3211 for primary TKA and $1853 for revision TKA. The payer mix included indemnity insurance, Medicare, Medicaid, managed care, and workmen's compensation. All payers were profitable except for Medicaid and selected managed care contracts for both primary and revision TKA. As a result of cost-containment programs, revision TKA can be profitable at our institution.     

Soft tissue balance measurement in posterior-stabilized total knee arthroplasty with a navigation system

Using a tensor for total knee arthroplasty (TKA) that is designed to facilitate soft tissue balance measurements with a reduced patello-femoral joint, we intraoperatively measured the joint gap and ligament balance of 30 osteoarthritic knees at extension and 90 degrees flexion, with the patella both everted and reduced, while performing primary posterior-stabilized TKA. At the same time, we performed the same measurements with a navigation system and identified correlations between this system and the tensor. Specifically, the R(2) values obtained with the knee in extension and 90 degrees flexion were higher with the patella reduced than with the patella everted. We thereby suggest that the navigation system we describe is reliable for obtaining accurate measurements of soft tissue balancing with the patella reduced.     

Arthrodesis Should Be Strongly Considered After Failed Two-stage Reimplantation TKA

Background

A two-stage reimplantation procedure is a well-accepted procedure for management of first-time infected total knee arthroplasty (TKA). However, there is a lack of consensus on the treatment of subsequent reinfections.

Questions/purposes

The purpose of this study was to perform a decision analysis to determine the treatment method likely to yield the highest quality of life for a patient after a failed two-stage reimplantation.

Methods

We performed a systematic review to estimate the expected success rates of a two-stage reimplantation procedure, chronic suppression, arthrodesis, and amputation for treatment of infected TKA. To determine utility values of the various possible health states that could arise after two-stage revision, we used previously published values and methods to determine the utility and disutility tolls for each treatment option and performed a decision tree analysis using the TreeAgePro 2012 software suite (Williamstown, MA, USA). These values were subsequently varied to perform sensitivity analyses, determining thresholds at which different treatment options prevailed.

Results

Overall, the composite success rate for two-stage reimplantation was 79.1% (range, 33.3%–100%). The utility (successful outcome) and disutility toll (cost for treatment) for two-stage reimplantation were determined to be 0.473 and 0.20, respectively; the toll for undergoing chronic suppression was set at 0.05; the utility for arthrodesis was 0.740 and for amputation 0.423. We set the utilities for subsequent two-stage revision and other surgical procedures by subtracting the disutility toll from the utility each time another procedure was performed. The two-way sensitivity analysis varied the utility status after an additional two-stage reimplantation (0.47–0.99) and chance of a successful two-stage reimplantation (45%–95%). The model was then extended to a three-way sensitivity analysis twice: once by setting the variable arthrodesis utility at a value of 0.47 and once more by setting utility of two-stage reimplantation at 0.05 over the same range of values on both axes. Knee arthrodesis emerged as the treatment most likely to yield the highest expected utility (quality of life) after initially failing a two-stage revision. For a repeat two-stage revision to be favored, the utility of that second two-stage revision had to substantially exceed the published utility of primary TKA of 0.84 and the probability of achieving infection control had to exceed 90%.

Conclusions

Based on best available evidence, knee arthrodesis should be strongly considered as the treatment of choice for patients who have persistent infected TKA after a failed two-stage reimplantation procedure. We recognize that particular circumstances such as severe bone loss can preclude or limit the applicability of fusion as an option and that individual clinical circumstances must always dictate the best treatment, but where arthrodesis is practical, our model supports it as the best approach.     

人工全膝关节置换术后深部感染的治疗

目的探讨人工全膝关节置换(total knee arthroplasty,TKA)术后深部感染的处理方法及疗效。方法2004年1月-2010年1月,收治TKA术后深部感染患者32例(32膝)。男13例,女19例;年龄52～79岁,平均64.6岁。TKA手术距发生感染时间为3周～10年。膝关节功能采用膝关节学会评分系统(KSS)为(104.6±9.1)分,疼痛视觉模拟评分(VAS)为(7.8±1.4)分。急性感染3例行关节切开清创后持续冲洗;急性血源性播散感染3例于关节镜下清创;慢性感染26例,其中行关节切开清创后持续冲洗9例,抗生素骨水泥隔体植入4例,二期翻修12例,抗生素保守治疗1例。结果急性感染者治疗均失败,急性血源性播散感染者1例治疗失败,慢性感染者7例清创及1例保守治疗失败;均经对症治疗后治愈。32例患者均获随访,随访时间2～8年,平均4.6年。末次随访时KSS评分为(158.4±8.3)分,VAS评分为(4.1±0.8)分,与术前比较差异有统计学意义(P<0.05)。随访期间再感染3例,均为二期翻修患者。结论TKA术后耐甲氧西林金黄色葡萄球菌急性感染切开清创成功率低;急性血源性播散感染可试行关节镜下清创;慢性感染二期翻修膝关节功能恢复良好,但远期存在再感染风险。