Gender differences in distal femoral morphology and the role of gender specific implants in total knee replacement: a prospective clinical study

Gender differences in distal femoral morphology may affect femoral component fit using a standard range of prostheses. The clinical relevance of this is controversial.Standardised measurements were taken from the distal femora of 50 males and 50 females during total knee replacement (TKR). Corresponding measurements were taken from the respective gender specific and standard femoral components. No demographic differences were noted.Significant differences in both frequency and magnitude existed in the medial-lateral femoral component overhang between the sexes. In females, standard implants overhung at the anterior flange width (AFW) by > 2 mm in 24/50 (48%) and by > 3 mm in 17/50 (34%) (p < 0.001). Also at the anterior medial-lateral width (MLA) 29/50 (58%) overhung by > 2 mm and 24/50 (48%) by > 3 mm (p < 0.001). In males, standard implants overhung by > 2 mm in 1/50 (2%). In females, gender specific implants overhung by > 2 mm in 3/50 (6%). Females had a mean aspect ratio of 1.02 (0.82 to 1.35) and men 0.98 (0.79 to 1.19).Femoral component overhang can occur in females undergoing TKR and a gender specific implant would reduce the potential for medial-lateral overhang. Long term studies are awaited to quantify the clinical implications of overhang.     

Two-year fixation and ten-year clinical outcomes of total knee arthroplasty inserted with normal-curing bone cement and slow-curing bone cement: A randomized controlled trial in 54 patients

BackgroundThe normal-curing Refobacin® Bone Cement R (RR) and slow-curing Refobacin® Plus Bone Cement (RP) were introduced after discontinuation of the historically most used bone cement, Refobacin®-Palacos® R, in 2005. The aim of this study was to compare total knee arthroplasty component fixation with the two bone cements.Methods54 patients with primary knee osteoarthritis were randomized to either RR (N = 27) or RP (N = 27) bone cement and followed for two years with radiostereometric analysis of tibial and femoral component migration and dual-energy x-ray absorptiometry measured periprosthetic bone mineral density (BMD). Further, patients were followed up at ten years with clinical outcome scores (OKS and KOOS).ResultsAt two-years follow-up, tibial total translation was 0.31 mm (95% CI: 0.19 – 0.42) for the RP group and 0.56 mm (95% CI: 0.45 – 0.67) (p < 0.01) for the RR group. There was continuous tibial component migration from one to two years follow-up (MTPM > 0.2 mm) in 13/27 patients from the RR and in 12/26 patients from the RP group. There was no difference between groups in BMD baseline values or changes during follow-up, as well as no correlation between change in BMD and tibial component migration. At ten-years follow-up, the improvement in the clinical outcome scores was similar between groups. There were no prosthesis related complications during the 10-year follow-up.ConclusionAt two years, tibial total translation was lower in the RP compared with the RR cement group, but BMD changes were similar. At ten years, no components were revised and clinical outcome scores were similar between groups.     

Mini-incision versus mini-incision and computer-assisted surgery in total knee replacement: a radiological prospective randomised study

The aim of this trial was to compare the radiological results of 74 patients undergoing a mini-invasive total knee replacement (TKR) using either a traditional alignment guide (MIS group) or a computer assisted alignment system (MICA group). All the patients were prospectively randomised to either group and the same implant was used for both groups. At 8 months post-operatively, the frontal femoral component angle (FFC), the frontal tibial component angle (FTC), the hip–knee–ankle angle (HKA) and the sagittal orientation of components (slopes) were evaluated respectively. The slopes of the femoral component and the FTC angle were statistically better aligned in the MICA group (p < 0.001). The MICA group showed both a significant fewer number of outliners and a significant higher number of implants with all five radiological parameters ideally aligned. The operative time was statistically longer in the computer assisted group.     

The effect of tourniquet use on fixation quality in cemented total knee arthroplasty a prospective randomized clinical controlled RSA trial

BackgroundA concern that arises with any change in technique is whether it affects the long-term implant stability. The objective of this study was to evaluate the early migration, measured by radiostereometric analysis (RSA), and the functional outcome of the Triathlon™ cemented knee prosthesis, operated on with or without a tourniquet. During the last decades RSA has emerged as a way to assess prosthetic fixation and long time prognosis. The method has been used extensively in both hip and knee arthroplasty.MethodThis was a single centre prospective study including 60 patients randomized into two groups operated on either with or without tourniquet. RSA investigation was done within 2–3 days postoperatively after full weight bearing, and then at 3 months, 1 year and 2 years postoperatively.ResultsThere were no differences between the groups regarding the translation along or rotation around the three coordinal axes, or in maximum total point motion (MTPM). At 2 years the mean MTPM (SD) was 0.71 mm (0.64) for the tourniquet-group and 0.53 mm (0.21) for the non-tourniquet-group.ConclusionsThe tibial tray of the Triathlon™ cemented knee prosthesis showed similar early stability whether operated on with or without tourniquet.Level of evidenceLevel I.Article summaryArticle focus: A safety study for total knee replacement operated on with or without perioperative tourniquet regarding the prosthetic fixation.Strengths and limitations: Strength of this study is that it is a randomized prospective trial using an objective measuring tool. The sample size of 25–30 patients is reportedly sufficient for the screening of implants using RSA (1–3).Trial registration: Clinical trials NCT01604382, Ethics Committee approval D-nr: 144/20085.     

Salmonella infection of a total knee replacement

Salmonella enterica serotype Choleraesuis is a rare infective pathogen in total knee arthroplasty and accounts for less than 1% of all cases. In the United Kingdom, the most prevalent organisms are Staphylococci, which account for over 50% of cases. We present an interesting case report of an infected revision total knee replacement following foreign travel to a region with an increased prevalence of Salmonella. The patient presented typically with an effused knee and raised inflammatory markers. Tissue samples demonstrated Salmonella choleraesuis as the infective organism. Though this serotype has previously been isolated from an infected total hip prosthesis, we believe this could be the first reported case involving a total knee replacement. Following involvement of our microbiology team and aggressive antibiotic therapy, the patient was successfully treated with two-stage revision surgery and at one-year post-op is making a satisfactory recovery.     

Technique and first clinical results of robot-assisted total knee replacement

Total knee replacement (TKR) is a common procedure for treatment of severe gonarthrosis, but the outcome may be unsatisfactory due to primary malalignment of the prosthetic components. In order to improve precision and accuracy of this surgical procedure, a commercial robotic surgical system (CASPAR) has been adapted to assist the surgeon in the preoperative planning and intraoperative execution of TKR. So far, 70 patients with idiopathic gonarthrosis were successfully treated with a robot-assisted technique in our institution. No major adverse events related to the use of the robotic system have been observed. The mean difference between preoperatively planned and postoperatively achieved tibiofemoral alignment was 0.8 degrees (0-4.1 degrees ) in the robotic group vs. 2.6 degrees (0-7 degrees ) in a manually operated historical control group of 50 patients. A clear advantage of robot-assisted TKR seems to be the ability to execute a highly precise preoperative plan based on computed tomography (CT) scans. Due to better alignment of the prosthetic components and improved bone-implant fit, implant loosening is anticipated to be diminished which may be most evident in non-cemented prostheses. Current disadvantages such as the need for placement of fiducial markers, increased operating times and higher overall costs have to be resolved in the future.     

The in vitro elution of gentamicin sulfate from a commercially available gentamicin-loaded acrylic bone cement, VersaBond AB

The present study was designed to yield results that would be used to contribute to the ongoing debate about the mechanism of the in vitro elution of an antibiotic from an antibiotic-loaded acrylic bone cement. To this end, the elution rates (R) of gentamicin sulfate (expressed as a weight percentage of the initial mass of the antibiotic in the specimen, normalized with respect to the duration of the test) from statically loaded (STATIC) and dynamically loaded (+/-10 MPa; 2 Hz; until fracture; DYNAMIC) specimens fabricated from a commercially available acrylic bone cement (VersaBond AB), in phosphate-buffered saline solution at 37 degrees C, were obtained with the use of a spectrophotometric method. There was evidence of microcracking in the fracture surfaces of DYNAMIC specimens, but no such evidence in the case of STATIC specimens. The surface area of the DYNAMIC specimens, during the tensile phase of the cyclical loading, was estimated to be about 3% larger than for the STATIC specimens (1742 mm(2) versus 1696 mm(2)). The bulk porosities P of the specimens in both sets were also determined and found to not be statistically different, with P for the STATIC and DYNAMIC specimens being 8.55 +/- 0.10 and 8.88 +/- 0.18%, respectively. At the end of the test period, R was found to be 0.36 +/- 0.20 and 1.28 +/- 0.14 wt %/day for the STATIC and DYNAMIC specimens, respectively. It is suggested that the present results provide support for the postulate that the elution mechanism of gentamicin in this cement is a surface phenomenon.     

Brucellar prosthetic arthritis in a total knee replacement

The infecting pathogens most commonly implicated in prosthetic joint infections are staphylococci, streptococci, and gram-negative rods. Prosthetic infections caused byBrucella spp, are rarely described in the literature. Treatment of prosthetic infections remains complex and controversial, the most accepted course being antibiotic treatment with removal or retention of prosthetic components. The case of a 60-year-old man who developedBrucella septic arthritis of the right knee in a total knee replacement is reported. Conservative treatment using a three-drug therapy was employed, with excellent results.     

Revision of failed unicompartmental knee replacement to total knee replacement

Recent reports suggest good outcome results following unicompartmental knee replacement (UKR). However, a number of authors have commented on the problem of osseous defects requiring technically difficult revision surgery. We reviewed clinical outcomes following revision total knee replacement (TKR) for failed UKR and analysed the reasons for failure and the technical aspects of the revision surgery. Between 2001 and 2010 our institute performed 132 UKR's out of which 33 required revision to TKR during a period 6 years. Demographics, details and indications for primary and revision surgery, the revised prosthesis including augments, technical difficulties and complications were noted. Patient outcome assessment was based on the Oxford knee score (OKS). Survival analysis for the UKR prosthesis was calculated using Kaplan-Meier Survival curves. Reasons for revision included aseptic loosening, persistent pain, dislocated meniscus, mal-alignment and other compartment osteoarthritis. Median time to revision was 19 months (range 2-159). Using revision as the end-point the survival proportion at 5-years was 69%. 18 revisions required additional intra-operative constructs including stemmed implants, wedge augmentation or bone graft. The mean 1 year post-operative OKS was 29 compared to 39 for primary TKR during the same period (p<0.001). Aseptic loosening was the commonest mode of failure. UKR survivorship at a non-specialist institute is considerably lower than at originating centres. Two thirds of the revisions were technically difficult and required additional constructs. The clinical outcome after revision surgery was inferior to that of primary TKR. The role of UKR needs to be more clearly defined.     

全膝关节置换术的康复治疗及护理

目的 探讨人工全膝关节置换术后的康复训练方法。方法 回顾分析2001年8月至2005年8月16例（17膝）人工全膝关节置换术后病人康复训练的过程及效果。结果 人工全膝关节置换术后经过系统康复训练，所有膝关节功能评分达到（70-86分）平均80分。结论 人工全膝关节置换手术效果与术后全面系统的康复训练密切相关。     

骨水泥与非骨水泥型全膝关节假体置换效果的系统评价

背景：国外研究调查显示,在全膝关节置换中有95.2%采用骨水泥进行假体固定,但是也有专家学者认为使用骨水泥固定假体风险高。 目的：应用Cochrane系统评价的方法评价膝关节置换中骨水泥型与非骨水泥型假体置换的效果差异。 方法：检索Medline(1996年1月至2011年8月)、Embase(1980年1月至2011年8月)、Cochranelibrary (2011年8月)、中国生物医学文献数据库(CBM, 1990年1月至2011年8月)及相关参考文献,收集骨水泥型和非骨水泥型假体全膝关节置换的随机对照试验,采用Cochrane的方法学评价文献质量,应用RevMan5.1.2 进行Meta分析。比较骨水泥型和非骨水泥型假体在术后生存率、稳定性、相关并发症、翻修率、异位骨化的差异。并使用GRADEpro version3.2.2软件对纳入研究进行证据评级。 结果与结论：纳入8个随机对照试验,共1 381例患者,实验组(骨水泥组)676例,对照组(非骨水泥组)705例。4个研究比较了骨水泥组和非骨水泥组假体置换后≤5年组的膝关节生存率,两组差异有显著性意义,说明置换后≤5年骨水泥组生存率高。4个研究比较了置换后>5年组膝关节生存率,两组差异有显著性意义,说明置换后>5年组骨水泥假体组生存率高。3个研究在不同随访时间比较了置换后假体稳定性,结果显示两组间在假体稳定性上差异无显著性。4个研究在不同随访时间比较了置换后假体相关的并发症,两组间在假体相关并发症上比较差异无显著性意义。5个研究在不同随访时间比较了置换后翻修率,两组间在假体翻修率上差异无显著性意义。3个研究在不同随访时间比较了置换后假体异位骨化,两组间在置换后假体异位骨化上差异无显著性意义。两组置换后疗效均较术前明显提高,组间比较的Meta 分析结果显示,不论是≤5年组还是>5年组,均是骨水泥型假体生存率均高于非骨水泥型假体生存率,两组在稳定性、相关并发症、翻修率、异位骨化等方面差异均无显著性意义(P > 0.05)。     

低浓度肾上腺素对减少全髋关节置换术中骨水泥植入综合征的影响

目的:探讨低浓度肾上腺素生理盐水混合液(1∶500 000)髓腔冲洗填塞法对全髋关节置换术(total hip replacement,THR)过程中生命体征及骨水泥植入综合征(bone cement implantation syndrome, BCIS)的影响.方法:将1 52名拟行THR的患者随机分为观察组(76例)和对照组(76例),其中对照组使用生理盐水冲洗及纱布填塞骨髓腔,观察组使用低浓度肾上腺素生理盐水混合液冲洗及纱布填塞骨髓腔,收集并比较两组患者在髓腔冲洗填塞后(T0)、骨水泥注入时(T1)与注入后5 min(T2)、10 min(T3)的生命体征变化情况及BCIS的发生率.结果:观察组在T1,T2的心率、收缩压、指尖血氧饱和度均明显高于对照组(P＜0.05),重复测量方差分析结果显示,两组在不同时间点的心率、收缩压、指尖血氧饱和度的组内效应、时间效应、交互效应均具有统计学意义(P＜0.05),在舒张压及中心静脉压的时间效应具有统计学意义(P＜0.001);观察组在呼吸窘迫、低氧血症和低血压性休克的发生率明显明显低于对照组(P＜0.05).结论:低浓度肾上腺素髓腔冲洗填塞法有利于维持患者在骨水泥植入过程中的生命体征稳定,减少BCIS的发生,对于确保THR患者的手术安全具有积极的促进作用.     

Wear debris-induced pseudotumour in a cemented total knee replacement

We present a case of wear debris-induced osteolysis around the tibial component of a cemented total knee replacement associated with an expansile pseudotumour in the head of the fibula.     

Accuracy of patellar resection in total knee replacement. A study using the medial pivot knee

A series of 80 patellae were randomly allocated to osteotomy by sawing or milling while implanting the medial pivot knee. Three landmarks were used to control the plane of the cut in the coronal plane. The lateral edge of the patellar tendon distally, and both medial and lateral edges of the quadriceps tendon proximally. A line drawn across the widest points if the patella (the patellar horizon) was used to analyse the slope of the cut (P angle) and the orientation of the patella relative to the trochlear groove both pre- and post-operatively (PF angle) on 45 degrees skyline views. No patellae were under resected. The mean thickness of the remnant was 16 mm (range 14-19).There was no difference between sawing and milling, but the former was technically preferable. No patellae were found to be subluxed. The mean P angle was 2 degrees (S.D. 3.2). The maximum P angle was 10 degrees , but in no cases did obliquity of cut with under resection of the medial patellar facet lead to lateral tilt of the patellar horizon. The mean post-operative PF angle was 2.3 degrees (S.D. 2.6). The majority of patellae retained a similar orientation to the patellar groove post-operatively. In three patients, the patella tilted laterally with respect to the groove. One resulted from under resection of the lateral patellar facet and two in which the slope of the cut was good, probably resulted from an error in femoral rotation. In all 80 knees, the patellar dome remained in full contact with the groove. Use of three fixed landmarks provides consistent patellar resection in terms of depth and slope. Errors in slope of up to 10 degrees do not cause patellar tilt but may lead to medial overload due to increasing thickness of the patella. Errors in femoral sizing and rotation are more potent causes of lateral tilt and overload.     

Early outcomes using a ‘kinematic retaining’ total knee replacement – A multicentre prospective study at two years follow-up

BackgroundAlthough predictable implant longevity in total knee replacement (TKR) is now established, work continues to satisfy the demands of patients who seek full restoration of the painless function of the native knee following TKR. This prospective study examines the early clinical outcomes of 156 patients implanted with a novel ‘kinematic-retaining’ (KR) implant.Methods156 Physica KR TKRs were implanted for primary osteoarthritis at three European centres. Patients were reviewed up to two years using radiographic, clinical and functional evaluations.ResultsOf the 137 patients retained at two years’ follow up, none had been revised. Within 6 post-operative months, 51.7% and 79.9% had excellent clinical and functional KSS values respectively, increasing to 81.8% and 88.3% beyond two years. Mean KSS improvement was 34.8 (from 48.6 to 83.4). All KOOS sub-scores improved significantly with total KOOS improving from a mean of 35.5 (SD ±13.0) to 86.5 (±13.7) at two years post-operatively. Pain and sports KOOS sub-scores improved rapidly during the early post-operative periods, with sustained improvements beyond this. Mean OKS improved by 44.1 (±5.1) at two years. VAS satisfaction scores improved significantly at all time points beyond six weeks. Mean FJS-12 was 75.7 at two years, with no significant effects of age or gender. No progressive adverse radiographic features were noted.ConclusionsEarly clinical and radiographic outcomes of this kinematic-retaining knee prosthesis are promising, with improvements in clinical parameters similar to, or exceeding those published in other contemporary TKR designs.Level of evidence: II, Multicentre Prospective cohort study.     

膝关节置换中应用骨水泥和止血带对凝血功能的影响

背景：有研究表明膝关节置换中骨水泥固定假体时骨水泥对患者的血液动力学及凝血功能的影响较大。 目的：观察膝关节置换中骨水泥和止血带对患者凝血功能的影响。 方法：采用随机对照研究方法,将骨性关节行单侧膝关节置换患者40例随机分成2组,置换时分别应用止血带和不用止血带。通过比较两组患者血浆凝血酶原时间、活化的部分凝血活酶时间、凝血酶时间、纤维蛋白原及血浆D-二聚体水平的变化,来观察膝关节置换中骨水泥和止血带对置换中凝血功能的影响。 结果与结论：两组患者在骨水泥置入后60,120 min,血浆凝血酶原时间值缩短(P < 0.05),纤维蛋白原和D-二聚体在注入骨水泥后增多(P < 0.05),其中止血带组的变化更为明显,两组患者在180 min时基本恢复正常,活化的部分凝血活酶时间及凝血酶时间在骨水泥注入前后均无明显变化,另外,所监测的凝血功能相关指标(血浆凝血酶原时间、活化部分凝血酶原时间、凝血酶时间、纤维蛋白原及D-二聚体的数值在注入骨水泥前后均在正常范围内。相比非止血带组,止血带组血浆凝血酶原时间缩短、纤维蛋白原及D-二聚体含量增多(P < 0.05)。说明膝关节置换中骨水泥应用后可以使单侧膝关节置换患者的凝血功能处于高凝状态,止血带可加重患者的高凝状态。     

Evaluation of wound healing after total knee arthroplasty in a randomized prospective trial comparing fondaparinux with enoxaparin

BACKGROUND: Fondaparinux, a new synthetic pentasaccharide has proven to be a more potent thromboprophylactic drug compared to enoxaparin after major orthopaedic surgery. However, the safety of fondaparinux regarding wound healing has not yet been investigated. METHODS: We performed a single-centre prospective clinical trial, in which patients undergoing total knee arthroplasty or revision of at least one of the components of a previous knee arthroplasty were randomly assigned to thromboprophylaxis with fondaparinux or enoxaparin. The trial included 109 patients and wound discharge was compared. Secondary outcome measures were the amount of blood in the suction drain, postoperative transfusion rate, change in haemoglobin levels, haematocrit, intervention rate, time to regain flexion and rate of symptomatic thromboembolic events. RESULTS: 55 patients were treated with fondaparinux and 54 with enoxaparin. Base-line characteristics were similar. In both groups wound dressings remained dry after five (5.17+/-2.5 and 5.19+/-3) days postoperatively. There were no significant differences in any of our outcome measures. CONCLUSIONS: We did not find any significant difference in wound healing with fondaparinux after major knee surgery. Post hoc analyses suggested the study should have had a sample size of 155 in each group. We believe this trial should be used as a pilot study for further investigations concerning the safety of thromboprophylaxis.     

Intra-synovial ropivacaine and morphine for pain relief after total knee arthroplasty: a prospective, randomized, double blind study

PURPOSE: Several analgesic techniques are available for pain management after a major operation. MATERIALS AND METHODS: From December 2005 to February 2006, a prospective, double-blind study was performed involving 90 patients who had undergone a total knee arthroplasty. Patients were randomly divided into three equal groups (n=30). Demographic data, including age, height, weight, knee score, visual analogue scale (VAS), and range of flexion were evaluated preoperatively. Before wound closure, patients were given intra-synovial injections of the following solutions: patients in group I received 40mL of 300mg ropivacaine with 1:200,000 epinephrine and 5mg morphine; patients in Group II received 40mL of 300mg ropivacaine with epinephrine; and patients in Group III received 50mL normal saline as a control. All patients received an epidural patient-controlled analgesia (PCA) for 24 postoperative hours. Analgesic efficacy was evaluated using the VAS at intervals of 2, 4, 6, 12, 24, 32, 40, and 48 hours postoperatively. During this period, the side effects, the dosage of rescue analgesia required, and the range of knee flexion were recorded for each group. RESULTS: There were no significant differences among the three groups with regards to the VAS and the required dose of rescue analgesia (p > 0.05). None of the groups demonstrated significant differences in the range of knee flexion and the incidence of postoperative nausea and emesis (p > 0.05). CONCLUSION: Therefore, we found that ropivacaine, alone or with morphine, injected into the synovial tissue, along with an epidural PCA has no additional benefits in pain control after a total knee arthroplasty.     

The level of the joint line after cruciate-retaining total knee replacement: a new coordinate system

This study assessed joint line changes after knee replacement surgery. Sixty consecutive cruciate-retaining total knee replacements were followed up. The height of the femorotibial joint line in extension and in 90 degrees flexion were analysed. A new coordinate system was used. It is based on two perpendicular axes applied to a lateral X-ray: one axis is drawn along the anterior cortex of the distal femur and the other axis overlies the intersection of the inter-condylar roof and the posterior femoral condyles. In patients with non-posterior stabilised implants, the landmarks chosen appear to be reliable and useful. In this study, the femorotibial joint line was displaced distally, and the surgical instrumentation was changed accordingly.