In vivo kinematics for fixed and mobile-bearing posterior stabilized knee prostheses

This is the first in vivo kinematic study to compare mobile-bearing with fixed-bearing prostheses in patients who had total knee arthroplasties. Femorotibial contact positions for 40 patients implanted with either a fixed-bearing or mobile-bearing prosthesis were analyzed using videofluoroscopy. Femorotibial contact paths were determined using a computer automated model-fitting technique. Nineteen of 20 patients in each group experienced posterior femoral rollback of their lateral condyles, with a mean of 3.6 and 3.7 mm for fixed-bearing and mobile-bearing prostheses respectively. Eighteen patients who had mobile-bearing prostheses and 17 patients with fixed-bearing knee prostheses experienced a normal pattern of axial rotation of 7.3 degrees and 4.1 degrees respectively. Eleven of 20 (55%) patients who had mobile-bearing prostheses implanted and eight of 20 (40%) patients who had fixed-bearing prostheses implanted did not experience femoral condylar lift-off. The remaining knees had condylar lift-off less than 2.4 mm for fixed-bearing prostheses and 1.7 mm for mobile-bearing prostheses, respectively. Patients who had mobile-bearing prostheses implanted experienced greater axial rotation and less condylar lift-off than patients who had fixed-bearing prostheses implanted. Both cruciate ligaments are sacrificed for the mobile and fixed-bearing total knee replacements. The results from the current study showed that, in both groups, the majority of patients experienced kinematics similar to those of a normal knee. However, the extent of lateral femoral condyle posterior rollback and the extent of axial rotation were less.     

固定平台与旋转平台假体用于外翻膝的早期疗效观察

目的:比较外翻膝人工全膝关节置换术应用旋转平台和固定平台两型假体的早期临床疗效。方法:选取2011年1月至2013年12月吉林大学第一医院骨关节外科由同一医师进行初次人工膝关节置换的17例(23膝)进行回顾性随访研究,其中男2例,女15例;年龄48～75岁,平均61.5岁。术前诊断为骨性关节炎14例(19膝),类风湿性关节炎3例(4膝),所有膝关节有外翻畸形。其中9例(12膝)使用固定平台型假体(PFC Sigma),8例(11膝)使用旋转平台型假体(PFC Sigma RP).术前和术后随访行KSS、HSS、WOMAC评分,测量关节活动度、胫股角等指标,进行统计学分析。结果:所有患者获随访,时间6～36个月,平均25个月。两组患者膝外翻畸形均得到矫正,术后末次随访的KSS、HSS、WOMAC评分及膝关节活动度、胫股角较术前明显改善(P<0.01).其中固定平台组和旋转平台组在术后KSS、HSS、WOMAC评分以及胫骨角、膝关节活范围改善度方面比较,差异无统计学意义(P>0.05);而术后末次随访膝关活动范围固定平台组(101.8±8.8)°与旋转平台组(108.4±7.2)°差异有统计学意义(P<0.05).旋转平台组没有发现垫片脱位,两组术后均无感染、腓总神经麻痹、脱位、膝关节不稳等并发症发生,X线检查未见假体骨溶解及松动发生。结论:外翻膝人工全膝关节置换术使用旋转平台和固定平台型假体均能获得满意的早期临床效果,两者的近期临床疗效比较无明显差异。     

Range of motion of standard and high-flexion posterior stabilized total knee prostheses. A prospective, randomized study

BACKGROUND: The restoration of posterior femoral translation has been shown to be an important factor in enhancing knee flexion after total knee arthroplasty. The purpose of this study was to compare the ranges of motion associated with standard and high-flexion posterior stabilized total knee prostheses in patients managed with simultaneous bilateral total knee arthroplasty. METHODS: Fifty patients (mean age, sixty-eight years) received a standard fixed-bearing knee prosthesis in one knee and a high-flexion fixed-bearing knee prosthesis in the contralateral knee. Two patients were men, and forty-eight were women. At a mean of 2.1 years postoperatively, the patients were assessed clinically and radiographically with use of the knee-rating systems of the Knee Society and The Hospital for Special Surgery. RESULTS: The mean postoperative Hospital for Special Surgery knee score was 90 points for the knees treated with the standard fixed-bearing prosthesis and 89.4 points for those treated with the high-flexion prosthesis. At the time of the final follow-up, the knees with the standard prosthesis had a mean range of motion of 135.8 degrees (range, 105 degrees to 150 degrees ) and those with a high-flexion prosthesis had a mean range of motion of 138.6 degrees (range, 105 degrees to 150 degrees ) (p = 0.41). No knee had aseptic loosening, revision, or osteolysis. CONCLUSIONS: After a minimum duration of follow-up of two years, we found no significant differences between the groups with regard to range of motion or clinical and radiographic parameters, except for posterior femoral condylar offset.     

A comparison of fixed-bearing and mobile-bearing total knee arthroplasty at a minimum follow-up of 4.5 years

BACKGROUND: Durable long-term independent results with the Low Contact Stress rotating-platform (mobile-bearing) and the Insall Burstein-II (fixed-bearing) total knee prostheses have been reported, but no studies describing either the mid-term or long-term results and comparing the two prostheses are available, to our knowledge. METHODS: Thirty-two patients who had bilateral arthritis of the knee with similar deformity and preoperative range of motion on both sides and who agreed to have one knee replaced with a mobile-bearing total knee design and the other with a fixed-bearing design were prospectively evaluated. Comparative analysis of both designs was done at a mean follow-up period of six years, minimizing patient, surgeon, and observer-related bias. Clinical and radiographic outcome, survival, and complication rates were compared. RESULTS: Patients with osteoarthritis had better function scores and range of motion compared with patients with rheumatoid arthritis. However, with the numbers available, no benefit of mobile-bearing over fixed-bearing designs could be demonstrated with respect to Knee Society scores, range of flexion, subject preference, or patellofemoral complication rates. Radiographs showed no difference in prosthetic alignment. Two knees with a mobile-bearing prosthesis required a reoperation: one had an early revision because of bearing dislocation and another required conversion to an arthrodesis to treat a deep infection. CONCLUSIONS: We found no advantage of the mobile-bearing arthroplasty over the fixed-bearing arthroplasty with regard to the clinical results at mid-term follow-up. The risk of bearing subluxation and dislocation in knees with the mobile-bearing prosthesis is a cause for concern and may necessitate early revision. LEVEL OF EVIDENCE: Therapeutic Level II.     

Clinical assessment of tibial polyethylene thickness: comparison of radiographic measurements with as-implanted and as-retrieved thicknesses

Sixty-six posterior cruciate-retaining inserts of one fixed-bearing design were revised because of wear or osteolysis. Tibial polyethylene thickness was estimated from standard anteroposterior radiographs and compared with the original or final minimum thicknesses. The most accurate method involved measuring the shortest distance from each femoral condyle to a transverse line through the middle of the baseplate's superior surface. On radiographs acquired 6 weeks after arthroplasty, the mean error was -0.1 mm (underestimate) +/- 0.6 mm (standard deviation), with 72% of the measurements within 0.5 mm of the original minimum thickness and 87% within 1.0 mm. The method was less accurate for radiographs made before revision, for which the mean error was 0.6 mm (overestimate) +/- 1.0 mm. In this study, 41% and 70% of the prerevision measurements were accurate to within 0.5 and 1.0 mm, respectively.     

Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. A study of patients followed for a minimum of fifteen years

BACKGROUND: There have been a limited number of studies of total knee arthroplasties with durations of follow-up of fifteen years, but we are not aware of any involving modular fixed-bearing posterior cruciate-retaining prostheses. METHODS: A consecutive series of 139 total knee arthroplasties in 109 patients (average age, sixty-seven years), performed by one surgeon using a nonconforming posterior cruciate-retaining prosthesis, was followed for fifteen years or longer. Forty-five patients (fifty-nine knees) were examined at a minimum of fifteen years postoperatively, fifty-seven patients (seventy knees) had died, five patients (eight knees) were too ill to return for assessment, and two patients (two knees) were considered lost to follow-up. The patients were assessed clinically with use of the Knee Society clinical rating system, and the knees were assessed radiographically. Survivorship analysis was performed with use of worst-case-scenario analysis and with failure defined as a reoperation for any reason. RESULTS: There were five reoperations, four of which were performed because of wear of the polyethylene insert. In addition, one loose cemented femoral component was revised at fifteen years. The survival rate without revision or a need for any reoperation was 92.6% at fifteen years. The mean Knee Society score and functional score at fifteen years were 96 and 78 points, respectively. The prevalence of radiolucent lines was 13%, with 2% around the femur, 11% around the tibia, and none around the patella. None of these lines were clinically relevant. There was no evidence of progressive radiolucent lines, and there was one case of asymptomatic femoral osteolysis. CONCLUSIONS: In this single-surgeon series, modular fixed-bearing posterior cruciate-retaining total knee arthroplasties had good clinical and radiographic results with excellent survivorship for up to fifteen years. These results are comparable with those in long-term studies of posterior stabilized implants and of prostheses with mobile-bearing and nonmodular tibial inserts.     

Mobile vs Fixed-Bearing Total Knee Arthroplasty Performed by a Single Surgeon : A 4- to 6.5-Year Randomized,Prospective, Controlled,Double-Blinded Study

The superiority between posterior-stabilized mobile-bearing and fixed-bearing designs still remains controversial. Fifty-six consecutive patients undergoing primary, unilateral knee arthroplasty for osteoarthritis were randomly assigned to receive either a mobile-bearing (29 patients) or fixed-bearing (27 patients) prosthesis. We report the results at 4 to 6.5 years (mean, 5.5) follow-up. The Knee Society knee scores, pain scores, functional scores and Oxford knee scores were not statistically different (P > 0.05) between the two groups. Mean postoperative range-of-motion of mobile-bearing knees was significantly greater than that of fixed-bearing knees (127º versus 111º, P = 0.011). 72% of patients could sit cross legged, 48% could sit on the floor, and 17% could squat. Kaplan–Meier survival rate was 100%. No spin-out of mobile bearing was observed. The radiological analysis showed no osteolysis or implant loosening.     

Long-term results of low contact stress mobile-bearing total knee replacements

Five hundred ninety-eight consecutive primary low contact stress total knee replacements were done in 502 patients between 1985 and 1990. Clinical review was available for 495 knees (406 patients), 228 knees with meniscal-bearing prostheses and 267 knees with rotating-platform prostheses. The average followup was 12 years (range, 10-15 years). The average postoperative knee and functional scores were 87 points and 75 points, respectively. The average postoperative range of motion was 110 degrees. Fifty-six knees (11%) required revision for excessive wear of the tibial insert (41), dislocation (10), patellar polyethylene breakage (one), component loosening (one patellar, one tibial), and infection (two). During revision, osteolysis (20 knees), patellar polyethylene failure (33), and femoral component fracture (one) were seen. The overall survivorship was 88.1% at 15 years using Kaplan-Meier analysis. The survival rate was 83% for the meniscal-bearing prostheses and 92.1% for the rotating-platform prostheses. The Low Contact Stress mobile-bearing knee prosthesis has no superiority over that of fixed-bearing knees, especially for the meniscal-bearing design in prevention of polyethylene failure or revision. Based on the results of this study, the use of the LCS meniscal-bearing prosthesis does not appear to be justified.     

Anterior-posterior glide mobile-bearing total knee arthroplasty: complications related to prosthesis design

The aim of this study was to evaluate complications related to prosthesis design in patients managed with cemented total knee arthroplasty using anterior-posterior glide mobile-bearing prosthesis. One hundred eighty-three total knee arthroplasties were performed using this prosthesis on 146 patients, with a minimum of 7 years of follow-up. There were late dislocations of the bearing in 2 knees, anterior soft tissue impingements in 6 knees at an earlier follow-up, excessive anteroposterior translation in 5 knees, and a fracture of the femoral component induced by osteolysis in 1 knee. Design modifications in the restraint mechanisms of the anterior-posterior glide mobile-bearing prosthesis may be required to minimize the development of complications with regard to sagittal instability and to improve the prosthesis' longevity.     

Mid-term survivorship results for a rotating-platform knee prosthesis

Interest in mobile-bearing knee prostheses is increasing in the US market. We studied results at 2 to 5 years with a mobile-bearing system that includes a cobalt-chrome tibial tray and femoral component with a polyethylene cruciate-retaining tibial component insert that allows rotation around a central axis and can be used with cruciate-retaining or posterior-stabilized femoral components. The inserts used in this study were cruciate retaining and did not include the posterior-stabilized design. The goal of this study was to demonstrate the function and safety of this prosthesis along with the lack of spinout, which is a major concern in the mobile-bearing knee. Four hundred thirty-five knees constituted the study cohort and underwent survivorship analysis and complication reporting. Routine clinic evaluations included pre- and postoperative radiographs and Knee Society knee and function scores at 6 and 12 weeks and every 2 years. The most recent follow-up data within 2 to 5 years was included for the study along with survey data. Flexion at most recent follow-up averaged 125°. Knee Society score at most recent visit averaged 88 of 100. Knee Society function score averaged 83 of 100. Radiographic results were available for 226 knees, with 97.3% assessed as normal and 6 with these issues: patella stress fracture (3), aseptic tibial loosening (1), patellar osteolysis (1), and patella aseptic loosening (1). In comparison with the fixed-bearing knee equivalent, this mobile-bearing knee demonstrated at least equivalent results in terms of survivorship, function, and patient satisfaction in the short- and mid-term.     

Prevalence of osteolysis after simultaneous bilateral fixed- and mobile-bearing total knee arthroplasties in young patients

This study aimed to evaluate the clinical and radiographic results and to document the prevalence of osteolysis associated with fixed-bearing (anatomic modular knee) and mobile-bearing (low contact stress) total knee arthroplasties (TKAs) in 61 patients younger than 55 years who had bilateral simultaneous primary TKAs. Forty-five patients were female and 16 patients were male. The mean age of the patients was 48.3 years (range, 34-55 years). The mean postoperative Knee Society knee and functional score were similar in both groups (91 and 90 points and 85 and 86 points, respectively). Three knees (5%) in each group were revised for wear of the tibial bearing, and 1 knee (2%) in the mobile-bearing TKA was revised for dislocation of the meniscal bearing. Osteolysis was identified in both radiographs and computed tomography scans in 6 knees (10%) in the anatomic-modular-knee group and 4 knees (7%) in the low-contact-stress group.     

Bilateral fatigue fracture of the femoral components in a cruciate-retaining cementless total knee prosthesis

This article reports a case of bilateral fatigue fracture of the femoral components in a cruciate-retaining uncemented total knee arthroplasty (TKA). A 75-year-old woman (height, 158 cm; weight, 72 kg; body mass index, 29.2) had undergone one-stage bilateral TKA for osteoarthritis 11 years previously at the author's institution. Surgery was performed using an uncemented Flexible Nichidai Knee. Equal tension of the collateral ligaments and normal mechanical axis were achieved during the primary procedure. The patient was an ardent lover of the game of badminton and had higher activity levels with daily playing. At 8 years postoperatively, she started complaining of mild pain in both knees. The pain gradually increased, and at 11 years postoperatively, she had difficulty walking. Anteroposterior radiographs showed narrowing of the medial joint space, indicating wear of the polyethylene insert. Lateral radiographs showed signs of broken implants in both knees. There were no signs of gross implant loosening or osteolysis. One-stage revision surgery was performed, and the knees were converted to cemented posterior-stabilized TKAs. At revision, the bilateral femoral components were found to be fractured at the junction between the trochlear flange and the medial condyle, anteriorly to the medial peg. The polyethylene insert showed mild wear at the medial middle portion. In the majority of case reports, stress fractures of the femoral component have predominantly affected the medial condyle, following uncemented implantation of fixed-bearing knees. In this case, failure of bone ingrowth in uncemented components, higher body mass index, and a higher athletic activity led to fatigue fracture of the femoral components.     

活动平台与固定平台全膝关节置换的比较研究

目的评价人工全膝关节置换术中使用活动平台和固定平台假体治疗膝骨关节炎的早期疗效。方法对2009年3月至2011年3月收治的诊断为膝骨关节炎的患者,随机应用活动平台型假体和固定平台型假体行全膝关节置换（total knee arthroplasty,TKA）手术。记录术前及随访时术膝的膝关节评分、疼痛评分、功能评分、髌骨评分和膝关节活动度,以及股骨角、胫骨角、膝外翻角、胫骨平台后倾角、截骨高度。结果术前活动平台组和固定平台组的年龄、体重指数、患膝内翻畸形、最大屈曲角度及屈曲挛缩度均无统计学差异（P〉0.05）。术后平均随访26个月,活动平台组和固定平台组的术前术后膝关节评分、疼痛评分、功能评分、髌骨评分均无统计学差异（P〉0.05）,都明显地改善了患膝的症状和功能。活动平台组和固定平台组的术后最大屈曲度间存在显著性差异（P〈0.05）。两组的股骨角、胫骨角、膝外翻角、胫骨平台后倾角、截骨高度和术前术后髌骨高度无显著性差异（P〉0.05）。结论活动平台型假体和固定平台型假体TKA均明显改善了患膝的症状和功能,两组的膝关节评分、功能评分、疼痛评分、髌骨评分及X线检查评价差异均无统计学意义。固定平台组的术后最大屈曲度大于活动平台组的最大屈曲度。     

活动和固定衬垫型假体在全膝关节表面置换术中的早期临床比较研究

目的通过文献回顾以及病例观察比较活动衬垫型假体和固定衬垫型假体在人工膝关节表面置换中的早期应用情况。方法2003年2月至2004年10月共对94例骨关节炎患者行初次全膝关节表面置换术。全部病例选用不保留后交叉韧带骨水泥型假体。A组(固定衬垫型假体)29例患者,30侧关节(20侧选用DePuy假体,10侧选用Centerpulse假体)。B组(活动衬垫型假体)65例患者,68侧关节,全部选用Centerpulse假体。A,B两组术前资料进行HSS评分、年龄、性别等可比性分析。术后6周、3个月、6个月、1年分别随访,进行HSS评分、患者满意度调查等评价。所得数据采用SPSS10.0软件系统进行统计学分析。结果A、B两组术后6周、3个月、6个月、1年所得HSS评分进行阶段统计学分析,所得P值分别为0.414,0.108,0.235,0.452,两组术后HSS评分差异无统计学意义。术后1年,两组膝关节活动度比较A组,平均ROM为108°(95°~118°);B组,平均ROM为107°(90°~120°),两组关节活动度差异无统计学意义(P>0.05)。术后1年,A组患者主诉4侧关节(13.7%)仍有疼痛,B组9侧关节(13.1%)主诉患肢仍有疼痛;A组90%患者对手术效果满意,B组88%患者对手术效果满意。结论本组研究结果尚未证实活动衬垫型假体相对于固定衬垫型假体在早期人工关节表面置换术后的优越性。     

固定平台后稳定型假体全膝关节置换术后的运动学研究

 目的 探讨固定平台后稳定型假体全膝关节置换(total knee arthroplasty,TKA)术后膝关节在负重屈膝下蹲时的运动学特征。方法 选取10名健康志愿者和10例固定平台后稳定型假体TKA术后患者。制作骨骼及膝关节假体三维模型,在持续X线透视下完成负重下蹲动作,膝关节屈曲度每增加15°截取一幅图像。通过荧光透视分析技术完成三维模型与二维图像的匹配,再现股骨与胫骨在屈膝过程中的空间位置,通过连续的图像分析比较正常与固定平台后稳定型假体TKA术后膝关节在负重下蹲时股骨内、外髁前后移动及胫骨内外旋转幅度。结果 负重下蹲时,正常膝关节平均屈曲136°,股骨内、外髁分别后移(7.3±1.2) mm和(19.3±3.1) mm,胫骨平均内旋23.8°±3.4°;TKA术后膝关节平均屈曲125°,股骨内、外髁分别后移(1.4±1.6) mm和(6.4±1.7) mm,胫骨平均内旋8.5°±3.4°。结论 固定平台后稳定型假体TKA术后膝关节运动与正常膝关节相似,均表现出股骨内、外髁后移及胫骨内旋运动,但幅度小于正常膝关节,且在屈膝过程中存在股骨矛盾性前移及胫骨外旋现象。     

Comparison of anterior-posterior-glide and rotating-platform low contact stress mobile-bearing total knee arthroplasties

BACKGROUND: The anterior-posterior-glide Low Contact Stress mobile-bearing knee prosthesis was developed to approximate the natural kinematics of the knee more closely than the rotating-platform Low Contact Stress mobile-bearing knee prosthesis does. The purpose of the present study was to compare the results associated with these two prostheses in patients managed with simultaneous bilateral total knee replacement. METHODS: One hundred and ninety patients received an anterior-posterior-glide Low Contact Stress mobile-bearing prosthesis in one knee and a rotating-platform Low Contact Stress mobile-bearing prosthesis in the contralateral knee. The mean age of the patients at the time of the index procedure was sixty-four years. Eleven patients were men, and 179 patients were women. The mean duration of follow-up was 6.4 years (range, five to seven years). The patients were followed clinically and radiographically with use of the knee-rating systems of the Knee Society and the Hospital for Special Surgery. RESULTS: The mean postoperative Hospital for Special Surgery knee score was 89.4 points for the knees treated with the anterior-posterior-glide mobile-bearing prosthesis and 88.6 points for those treated with the rotating-platform mobile-bearing prosthesis. Three knees in each group had a poor result. Two knees in each group had persistent moderate pain. One knee with an anterior-posterior-glide prosthesis had permanent tibial and deep peroneal nerve palsies, and one knee with a rotating-platform prosthesis had a permanent deep peroneal nerve palsy. No knee had aseptic loosening, revision, measurable wear of the tibial or patellar polyethylene bearing, or osteolysis. CONCLUSIONS: After a minimum duration of follow-up of five years, the results associated with the anterior-posterior-glide and rotating-platform Low Contact Stress mobile-bearing total knee replacements were favorable and comparable.     

The role of registry data in the evaluation of mobile-bearing total knee arthroplasty

The conventional wisdom that a mobile-bearing design may offer a benefit compared with a fixed-bearing design in total knee arthroplasty has not been supported by evidence. We reviewed the published literature and annual registry reports of all national and regional registries to determine the differences in clinical outcomes between mobile and fixed-bearing designs. We found only single-center reports and studies with small sample sizes in the published literature. These studies did not demonstrate any advantages of mobile bearings over fixed bearings. Moreover, major national joint registries reported higher failure rates associated with mobile-bearing total knee replacement compared with fixed-bearing total knee replacement. Similar findings from a U.S. national study in a community setting suggest that mobile-bearing knees have an increased risk of revision. After harmonization of methodologies, international collaborations of registries may provide the best insight into the performance of mobile-bearing total knee arthroplasty in real-world settings.     

固定平台型与活动平台型膝关节假体人工全膝关节置换术后膝前痛的比较研究

目的比较采用固定平台型与活动平台型膝关节假体行人工全膝关节置换术(total knee arthroplasty,TKA)后发生膝前痛的差异。方法 2008年1月-10月收治72例骨性关节炎患者,其中37例采用固定平台型膝关节假体置换(固定平台组),35例采用活动平台型膝关节假体置换(活动平台组)。固定平台组:男8例,女29例;年龄57～76岁,平均69.6岁。左膝20例,右膝17例。体重55～92 kg,平均66.7 kg。体重指数(body mass index,BMI)为17.6～37.3,平均26.2。病程3～22年。根据膝关节学会评分系统(KSS)标准评定膝评分(29.4±15.3)分,功能评分(33.4±16.8)分。髌骨评分(7.2±2.5)分,疼痛评分(2.5±2.2)分。Insall-Salvat(iI-S)指数为1.6±0.3。活动平台组:男9例,女26例;年龄58～73岁,平均68.2岁。左膝30例,右膝5例。体重50～86 kg,平均67.9 kg。BMI为18.4～34.4,平均25.6。病程6～18年。KSS膝评分(30.9±14.7)分,功能评分(31.4±14.4)分。髌骨评分(6.8±3.1)分,疼痛评分(2.0±2.3)分。I-S指数为1.6±0.2。两组患者一般资料比较,差异均无统计学意义(P>0.05),具有可比性。结果两组患者术后切口均Ⅰ期愈合,无下肢深静脉血栓形成及肺栓塞发生。患者术后均获随访,随访时间为12～16个月。术后活动平台组发生膝关节感染1例,膝关节脱位1例,膝关节弹响3例;固定平台组发生膝关节弹响1例。两组末次随访时KSS膝评分及功能评分、疼痛评分及髌骨评分比较,差异均无统计学意义(P>0.05);两组以上指标分别与术前比较,差异均有统计学意义(P<0.05)。末次随访时两组适合角、外侧髌骨角、髌骨倾斜角、髌骨外移距离、髌骨移位距离及I-S指数比较,差异均无统计学意义(P>0.05)。术后1～5个月固定平台组7例(18.9%)、活动平台组5例(14.3%)出现膝前痛。两组膝前痛发生率比较,差异无统计学意义(χ2=0.227,P=0.634)。术后出现膝前痛患者KSS膝评分、功能评分、髌骨评分及I-S指数与未出现膝前痛患者比较,差异均有统计学意义(P<0.05);其余各指标差异均无统计学意义(P>0.05)。结论采用固定平台型与活动平台型膝关节假体行TKA术后膝前痛发生率及术后近期疗效无明显差异。     

The kinematics of fixed- and mobile-bearing total knee arthroplasty

The success of any total knee arthroplasty (TKA) is influenced by a complex interaction between component geometry and the surrounding soft tissues. The objective of this study was to investigate posterior femoral translation and tibial rotation in a single design posterior-stabilized TKA offering fixed- and mobile-bearing tibial components. Specifically, we examined whether mobile-bearing TKA restores normal knee translation and rotation better than fixed-bearing TKA design. Eleven human knee specimens retrieved postmortem were tested using a robotic system. The translation and rotation of the intact and reconstructed knees were compared. The data indicate that for all knees, posterior femoral translation occurs along the passive path and under muscle loading conditions. Furthermore, increasing flexion angle corresponded with increased internal tibial rotation. Femoral translation and tibial rotation for fixed- and mobile-bearing posterior-stabilized TKAs were similar despite component design variations. However, both arthroplasties only partially restored intact knee translation and rotation. The data presented here may serve as an aid in the development of a rationale for additional improvement in surgical techniques and prosthesis design, so that normal knee function may be restored.     

Long-term comparison of mobile-bearing vs fixed-bearing total knee arthroplasty

Few published reports have been published regarding a comparison of the long-term outcomes between mobile- (MB) and fixed-bearing component designs for knee arthroplasty. The minimum 10-year clinical and radiologic follow-up of an unselected consecutive series of 89 patients (107 knees) who were randomized to have one of these different designs for primary arthroplasty was done. Twenty-six patients (30 knees) who had a fixed-bearing design and 24 patients (33 knees) who had an MB prosthesis were available for follow-up. Two MB knees were revised for aseptic loosening of a tibial component in one and femoral component fracture in the other. In patients who did not have revision surgery, there were no differences between the groups with respect to mean Knee Society scores, knee flexion, or pain scores.