The early results of high-flex total knee arthroplasty: a minimum of 2 years of follow-up

We retrospectively reviewed our first 25 cases of high-flex total knee arthroplasty (TKA) with an average follow-up of 28 months. The results were compared to a matched group of posterior stabilized (PS) TKA. There was no significant difference in Knee Society Scores between the 2 groups. The high-flex group had an averaged 138 degrees of knee flexion, which was significantly higher than the PS group (average, 126 degrees). Eighty percent of patients in high-flex group were able to squat, which was significantly higher than in PS group (32%). In patients with a small bone frame, occasionally, their bone stock of the posterior femoral condyle is inadequate for high-flex TKA. For the patients without special demands, the additional knee flexion from high-flex design made no significant difference on the results.     

The posterior stabilized knee prosthesis

The posterior stabilized knee prosthesis is a versatile and durable prosthesis with an excellent clinical record. It was designed to increase range of motion, improve stair climbing, and prevent posterior tibial subluxation.     

In-vivo kinematics of high-flex posterior-stabilized total knee prosthesis designed for Asian populations

Purpose

The purpose of this study was to determine in-vivo kinematics of our developed posterior-stabilized (PS) total knee prosthesis for Asian populations in comparison with a popular high-flexion PS prosthesis.

Methods

We analyzed 62 osteoarthritic knees: 31 knees with the new PS prosthesis (group A) and 31 knees with a popular high-flexion PS prosthesis (group B). Radiographic knee images were taken during standing, lunge, and kneeling activities. The three-dimensional position and orientation of the implant components were determined using model-based shape matching techniques.

Results

Group A showed slightly greater implant flexion angles compared with knees with conventional prosthesis at maximum lunge (average: 119 vs. 110°, p?=?0.001), and at maximum kneeling (121 vs. 114°, p?=?0.004), although the range of motion was not significantly different. The femoral centre positions were more posterior in group A at standing, at 90° lunge, at maximum lunge (-9 and -7 mm, p?=?0.004), at 90° kneeling, and at maximum kneeling (-9 vs. -7 mm, p?=?0.016), and posterior translations of the femoral center were greater at 90° knee flexion postures. The femoral centre positions had a strong negative correlation with implant flexion angles at maximum lunge in group B (r?=?-0.893, p?<?0.001), but not in group A (p?=?0.242).

Conclusions

The new PS prosthesis designed for Asian knee morphology achieved flexion angles and range of motion at least comparable to that of conventional high-flexion PS prosthesis. The femoral roll-back pattern, however, is different from a conventional knee, reflecting the post/cam design.

     

Midterm survivorship and clinical outcome of INDUS knee prosthesis: 5 year followup study

Background:

INDUS knee implant has been designed as per the anatomical morphology of the Indian population and has shown good clinical outcome in short term studies. The purpose of the present study was to report the midterm survivorship and clinical outcome of this implant.

Materials and Methods:

Two hundred and twenty three primary total knee arthroplasties in 209 consecutive patients using the INDUS knee prosthesis were prospectively enrolled. There were 145 females (155 knees) and 64 males (68 knees) with a mean age of 69.95 years (range 42–86 years). Annual followup with clinical and radiological examination was conducted, and a survivorship analysis was done using the Kaplan–Meier analysis.

Results:

Mean followup was 5.8 years (range 5–6.5 years). Eleven patients died while eight were lost to followup and a total of 204 knees were available for followup. The mean knee flexion improved from preoperative 110.4° ± 11.24° (range 60°–130°) to 128.17° ± 8.32° (range 100°–140°) at the final followup. The mean knee score improved from 40.1 ± 10.7 to 90.3 ± 5.34 while the function score improved from 44.35 ± 12.9 to 89.58 ± 7.43. Two patient developed infection and required revision. The Kaplan–Meier analysis reported a survivorship of 98.6% (confidence interval 95.7–99.6%) at the end for 5 years for INDUS knee prosthesis.

Conclusion:

INDUS knee prosthesis has excellent survivorship with a good clinical outcome and low failure rate.     

Posterior stabilized prosthesis. Results after follow-up of nine to twelve years.

We reviewed, nine to twelve years postoperatively, the records on an original cohort of 289 arthroplasties (218 patients) in which a posterior stabilized knee prosthesis with an all-polyethylene tibial component had been inserted at The Hospital for Special Surgery. One hundred and eighty intact prostheses in 139 patients were available for this analysis. Fourteen knees in fourteen patients had had a revision procedure. Five of these fourteen patients had had a bilateral arthroplasty, but only one knee of each of the five patients had been revised. Forty-eight of the patients (sixty-six knees) had died less than nine years after the operation. Twenty-nine other knees (twenty-two patients) had been lost to follow-up before a nine-year evaluation could be performed. Considering all 194 knees (including the fourteen that had been revised), the result with the system of The Hospital for Special Surgery was excellent for 117 knees (61 per cent), good for fifty-one (26 per cent), fair for twelve (6 per cent), and poor for the fourteen knees (7 per cent) that had been revised. The 180 knees in which the prosthesis was intact were also rated with the new scoring system of The Knee Society: the average postoperative knee score was 92 points (range, 35 to 100 points), and the average score for function was 66 points (range, 0 to 100 points). Survivorship analysis showed that the average annual rate of failure was 0.4 per cent and that the over-all rate of success at thirteen years was 94 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)     

单半径后稳定型假体全膝置换术后的中期随访报告

目的探讨单半径后稳定型假体全膝关节置换术后中期疗效。 方法回顾性研究上海市东方医院骨科自2012年6月至2015年1月,应用单半径后稳定型假体行全膝关节置换术(TKA)的20例(20膝)为观察组,纳入标准：初次单侧TKA,符合膝关节骨关节炎诊断标准;排除标准为双侧全膝关节置换术TKA或合并其他手术、药物成瘾、严重肝肾功能不全、类风湿关节炎、痛风性关节炎等其它炎症疾病、膝关节感染或可疑感染。其中女15例,男5例;平均年龄(68.3±0.5)岁。对照组20例为采用多半径后稳定型假体全膝置换。采用记录术前、末次随访美国膝关节协会评分(KSS评分)、膝关节功能评分,观察组与对照组的年龄、身体质量指数(BMI)、手术时间、KSS评分、功能评分比较采用t检验;观察组的术前与术后KSS评分、KSS功能评分及对照组的术前与术后KSS评分、KSS功能评分比较采用t检验,性别比例采用卡方检验。 结果所有病例均无感染,松动及静脉血栓症,平均随访(4.1±0. 6)年。术后随访X线片观察膝关节假体位置、力线等均显示良好。两组术后膝关节KSS评分(t＝1.428,P <0.05)、膝功能评分比较(t ＝2.75,P<0.01)差异均有统计学意义。 结论单半径后稳定型假体中期有令人满意的临床疗效。     

The total condylar knee prosthesis: the first 5 years

The total condylar knee prosthesis evolved from previous experience with other prostheses at the Hospital for Special Surgery. This evolution includes patellar resurfacing. Subsequent modifications have led to the total condylar knee prosthesis II (a cruciate substituting prosthesis), and the total condylar knee prosthesis III (a TCP II with increased constraint). The surgical technique requires ligamentous balance with correction of preoperative deformity by a soft-tissue release. Subsequently a standard operation is performed. Four hundred and sixty-one knees were reviewed with a minimum of one year follow-up and a maximum of 5 years. Seventy-five per cent were osteoarthritic knees. Using the Hospital for Special Surgery Knee Rating Scale, the results were excellent in 312 knees (68%), good in 109 knees (23.5%), fair in 18 knees (4%) and poor in 22 knees (4.5%). Osteoarthritic knees (excellent or good 93.5%) did slightly better than rheumatoid knees (excellent or good 87%). Complications include 6 infections, 6 subluxations and 10 cases of component loosening. There were 15 reoperations (3%). The results approach total hip arthroplasty in quality and so far have not deteriorated with time.     

A third-generation, posterior-stabilized knee prosthesis: early results after follow-up of 2 to 6 years

Two hundred seventy-nine primary total knee arthroplasties were performed with a modular, cemented, third-generation, posterior-stabilized prosthesis. At mean follow-up of 48 months (range, 24-72 months), the outcomes of 238 knees (85%) were evaluated with the Knee Society's Knee and Functional Scoring Systems and Roentgenographic Scoring System. The mean preoperative Knee Society Knee Score was 48 points compared with 96 points at latest follow-up. There were no cases of patellar clunk, symptomatic patellar maltracking, or posterior dislocation. There was no radiographic evidence of loosening or osteolysis, and no revisions were performed or recommended for loosening, osteolysis, instability, or polyethylene wear. Three patients developed late infections. These early results support the ongoing use of this design; however, long-term studies will be required.     

The mechanics of the knee and prosthesis design

The mechanisms controlling and limiting movement and serving to transmit load between the femur and the tibia are discussed. Having accounted for the transmission of all components of force and couple across the joint and noted the load-bearing role of the menisci, some principles which might guide the design of knee prostheses are deduced. It is shown that current designs transgress some of these principles. An experimental prosthesis is then described, which incorporates analogues of the natural menisci. The possible practical application of this novel principle has been studied in cadaveric human joints and in living patients.     

The Denham prosthesis in revision knee surgery: a 10 year follow-up

We studied the Denham knee prosthesis (Biomet, Warsaw, IN) in revision of total knee arthroplasty (TKA) in situations of extreme bone loss or ligamentous disruption including revision from previous hinged implants. We reviewed 34 patients (38 knees) at an average of 7. 5 years after surgery (range 4-12 years). No patient was lost to follow-up although 15 unrelated deaths occurred during the study. There were six failures, of which five were due to infections in patients who received a revision for infection. A further two patients experienced a poor result. The remaining 30 patients had an excellent or good result. In our setting, the Denham TKA effectively addressed problems of loss of bone stock and ligamentous disruption with simple instrumentation and a remarkably small number of implants.     

The AGC total knee prosthesis at average 11 years

A retrospective study of a series of 126 consecutive primary cemented total knee replacements using the AGC prosthesis is reported. Sixty-two knees were available for long-term review with an average clinical follow-up of 11.4 years (range, 8.4-13.6 years). The survivorship was 95%, defining the endpoint as revision of all components for any reason except sepsis. The average knee flexion was 110.9 degrees. The average Knee Society score was 91, and the average Knee Society Functional score was 67. There was no finding of tibial polyethylene failure, wear debris-generated osteolysis, or tibial or femoral loosening. Seven metal-backed patellae developed wear-through at an average of 80.4 months (7 of 126 for a 5.5% failure rate), with 3 (2.3%) resulting in complete revision. The authors continue to use the AGC prosthesis with an all-polyethylene patella. Compared with historical controls, the AGC has comparable survivorship.     

后稳定型全膝关节假体置换术后疗效分析

目的　分析后稳定型全膝关节假体置换术的处理方式、手术经验及疗效。方法　对 14例15膝行关节置换 ,使用Apollo后稳定型假体 ,单膝关节置换 13例 ,双膝同期置换 1例。原发疾病为类风湿性关节炎 3例 4膝 ,骨关节炎 11例 11膝。术后随访时间平均 11个月。结果　 15个膝关节术前伸曲活动度平均 75°,全膝关节置换术后 2个月关节活动度恢复至平均 10 0°。 14例患者均可自如行走、上下楼梯 ,膝关节稳定性好。 1膝术后脂肪液化致表层伤口裂开 ,清创后愈合 ,余膝术后伤口均愈合良好。结论　后稳定型假体植入的全膝关节置换手术方式简单、疗效肯定、术后并发症少。     

Unicompartmental knee replacements with Miller-Galante prosthesis: Two to 16-year follow-up of a single surgeon series

We report the outcome of 94 Miller-Galante unicompartmental knee replacements done by a single surgeon over 16 years in a district general hospital in the UK. Patellofemoral arthritis was considered a contraindication only if symptomatic and confirmed on radiography and surgery. Deformity when present was correctable. The mean age at surgery was 66.54 years. The mean follow-up was 10.8 years (2–16 years). The mean Bristol knee score was 43.1 (28–50); 86% of the patients had good or excellent scores. The average range of flexion was 110.6° (80–130°); 89% of the knees had an appropriate alignment. Using revision as the endpoint, outcome for every knee was established. The survival rate for medial unicompartmental knee replacements was 94% at ten years and 87% at 15 years. Although the survival rate for the lateral unicompartmental knee replacement was 97% at five years, it dropped to 41% at eight years. Lateral unicompartmental knee replacements formed only 9.6% of all the replacements in this series. The results for medial unicompartmental knee replacements are similar to reports by other authors for similar and mobile bearing designs. Unicompartmental knee replacement results in a more kinematic knee and produces good functional results.     

Conversion of a fused knee with use of a posterior stabilized total knee prosthesis

BACKGROUND: Typically a hinged or condylar constrained prosthesis is recommended for total knee arthroplasty in a fused knee, to substitute for the absent or deficient collateral ligaments. The purpose of this study was to evaluate the stability and clinical results after the use of a posterior stabilized prosthesis in the conversion of a fused knee to a total knee arthroplasty. METHODS: Thirty-six patients (thirty-six knees) with a mean age of 39.2 years underwent conversion of a fused knee to a total knee arthroplasty with a posterior stabilized prosthesis. The mean duration of ankylosis had been 24.5 years. Clinical and radiographic evaluation was carried out preoperatively; at six weeks and three, six, and twelve months postoperatively; and annually thereafter. The mean duration of follow-up was 7.7 years. RESULTS: The mean preoperative Hospital for Special Surgery knee score of 60 points improved to 83.2 points at the final follow-up examination. Twenty-two knees were pain-free, and the remaining fourteen were mildly painful after prolonged walking. The mean amount of active flexion in the entire group was 77.7 degrees. The extension lag in the entire group averaged 12.5 degrees. Complications included necrosis of the skin edges in eighteen knees (50%), a rupture of the quadriceps tendon in two patients, and a pyogenic infection in two. No prosthesis required revision because of clinical or radiographic loosening. CONCLUSIONS: We believe that when the soft-tissue sleeves in a previously fused knee are carefully preserved intraoperatively, they can provide adequate stability after total knee arthroplasty with a posterior stabilized prosthesis. Therefore, we believe that use of that type of prosthesis is a reasonable alternative to the use of a more constrained implant in the treatment of this condition.     

Total knee arthroplasty with the kinematic prosthesis. Results after five to nine years: a follow-up note

A review of the results of 192 kinematic total knee replacements five to nine years after the operation showed that the results were still satisfactory. At the time of the review, the ages of the patients ranged from twenty-two to eighty-seven years. About half of the patients had rheumatoid arthritis and the other half, osteoarthrosis. About 90 per cent of the results were rated good or excellent, and the average range of flexion was 109 degrees. Radiolucency was present around 40 per cent of the tibial components, 30 per cent of the femoral components, and 60 per cent of the patellar components, but the lines were thin and not progressive. The complications included loosening of the patellar components in five knees, one fracture of the tibial tray with loosening of the patellar component, one fracture of the patellar component, and one dislocation of the patellar component.     

The influence of tibial-patellofemoral location on function of the knee in patients with the posterior stabilized condylar knee prosthesis

Function of the knee and patellofemoral symptoms were correlated with the position of the implant in 101 consecutive patients with 116 posterior stabilized condylar knee prostheses. All of the patients were followed for a minimum of two and a half years with sequential physical examinations, radiographs, and functional evaluation of the knee. In sixteen knees (14 per cent), clicking or catching of the patella in terminal extension or painless crepitation throughout the arc of flexion developed without lowering the functional knee-evaluation score. Pain or mechanical problems, or both, that lowered the functional knee-evaluation score occurred in another fourteen knees (12 per cent), within the first postoperative year. Of these fourteen, eight required revision solely for patellofemoral complaints. Critical analysis of the tibial-patellofemoral mechanical axis identified three surgical variables that were found to markedly affect the functional result of the prosthesis: the distance from the center line of the tibial prosthesis to the center line of the tibial plateau, a change in the position of the joint line of the prosthesis relative to the hip and ankle, and the patellar height, measured as the perpendicular distance from the inferior pole of the patellar implant to the joint line of the prosthesis. Functional knee scores, range of motion, patellofemoral pain or mechanical symptoms, the need for revision, and the necessity of manipulation could all be statistically significantly correlated with the three independent variables. In addition, a range of neutral alignment was developed.(ABSTRACT TRUNCATED AT 250 WORDS)