Knee stability before and after total and unicondylar knee replacement: in vivo kinematic evaluation utilizing navigation

Surgical navigation systems are currently used to guide the surgeon in the correct alignment of the implant. The aim of this study was to expand the use of navigation systems by proposing a surgical protocol for intraoperative kinematics evaluations during knee arthroplasty. The protocol was evaluated on 20 patients, half undergoing unicondylar knee arthroplasty (UKA) and half undergoing posterior-substituting, rotating-platform total knee arthroplasty (TKA). The protocol includes a simple acquisition procedure and an original elaboration methodology. Kinematic tests were performed before and after surgery and included varus/valgus stress at 0 and 30 degrees and passive range of motion. Both UKA and TKA improved varus/valgus stability in extension and preserved the total magnitude of screw-home motion during flexion. Moreover, compared to preoperative conditions, values assumed by tibial axial rotation during flexion in TKA knees were more similar to the rotating patterns of UKA knees. The analysis of the anteroposterior displacement of the knee compartments confirmed that the two prostheses did not produce medial pivoting, but achieved a postoperative normal behavior. These results demonstrated that proposed intraoperative kinematics evaluations by a navigation system provided new information on the functional outcome of the reconstruction useful to restore knee kinematics during surgery.     

术前活动度对人工全膝关节置换术后功能影响的观察

目的回顾性分析患者手术前的活动度对人工全膝关节置换(TKA)术后功能的影响。方法随访2000年1月—2003年12月在我科行TKA的患者65例(97膝),年龄64．8±9．9岁(35～85岁)。其中骨性关节炎55例(81膝),类风湿关节炎10例(16膝)。单膝置换33例,双膝同时置换32例。所有患者按术前膝关节活动度数(ROM)分成两组,≤90°(5°～90°)49膝,>90°(95°～140°)48膝。对两组患者进行疗效(最大屈膝度、活动度、KSS评分及功能评分)对比。所有患者均采用Scorpio后稳定型骨水泥固定的假体,均为初期置换,全部手术由同一组医师完成。术后3 d在同一康复师指导下行患肢CPM及主动功能锻炼至出院。结果平均随访时间29个月(10～44个月)。所有膝关节的活动度从术前的平均84．2°(5°～140°)提高到术后的平均101．6°(40°～140°) (P=0．000);而最大屈膝度数术前的平均103．5°(25°～140°)与术后的平均101．6°(40°～140°)无显著差异(P=0．439);KSS膝关节评分从术前平均19．5分(-24～62分)提高到术后平均78．8分(50～95分)(P=0．000)。所有患者的总满意度为93．8％(61／65)。两个分组比较,ROM≤90°的膝关节ROM及最大屈膝度术后均较术前有提高,而ROM>90°的膝关节平均最大屈膝度术后反而下降。没有翻修及深部感染。结论(1)在影响TKA术后膝关节功能的多种因素中,手术技术是关键因素。(2)在其他因素相同的情况下,术前膝关节的活动度对TKA术后的功能也有很大的影响,术前活动度大的膝关节比那些术前活动度小的膝关节术后能获得更好的功能。     

Effect of total knee arthroplasty on maximal flexion

The advantage of potential flexion offered by total knee arthroplasty (TKA) is limited. In this review of 724 replaced knees, only one-third flexed to 105 degrees, while nearly one-half did not flex beyond 90 degrees. Postoperative flexion depended partly on preoperative flexion and partly on the prosthesis used, but these factors could not be the only determinants of results, for flexion in individual knees could increase, decrease, or remain unchanged whatever the preoperative measurement and whatever the design of prosthesis. Little difference in flexion before or after TKA was found between rheumatoid and osteoarthritic knees. Success or failure of the implant, according to the crude definition used, was not associated with degree of flexion. Patients with the lowest levels of function tended to have TKA with the least flexion and vice versa. Nevertheless, the degree of flexion is only one of the factors influencing mobility.     

Influence of intra-operative parameters on postoperative early recovery of active knee flexion in posterior-stabilized total knee arthroplasty

Purpose

Active knee flexion is more important for daily activities than passive knee flexion. The hypothesis is that the intra-operative parameters such as osteotomized bone thickness and soft tissue balance affect the postoperative active flexion angle in total knee arthroplasty (TKA). Therefore, we evaluate the influence of intra-operative parameters on postoperative early recovery of active flexion after posterior-stabilized (PS) TKA.

Methods

The subjects were 45 osteoarthritic knees undergoing primary PS TKA with anterior-reference technique. Intra-operative soft tissue balance was measured using an offset type tensor, and each osteotomized bone thickness was also measured. Pre- and postoperative active knee flexion angles were measured using lateral radiographs. Liner regression analysis was used to determine the influence of these intra-operative parameters on postoperative active flexion angles or recovery of active flexion angles.

Results

Pre-operative flexion angle was positively correlated with postoperative flexion angle (R?=?0.52, P?=?0.0002). Postoperative flexion angle was negatively correlated with the osteotomized bone thickness of femoral medial posterior condyle (R?=??0.37, P?=?0.012), and femoral lateral posterior condyle (R?=??0.36, P?=?0.015). Recovery of flexion angle was slightly negatively correlated with gap difference calculated by subtracting joint gap at extension from that at flexion between osteotomized surfaces (R?=??0.30, P?=?0.046).

Conclusions

The osteotomized bone thickness of the femoral posterior condyle is a significant independent factor of postoperative flexion angles. This indicates that the restoration of the posterior condyle offset may lead to larger postoperative active flexion angles in PS TKA.     

Knee Flexion Angle Following Total Knee Arthroplasty Relates to a Preoperative Range of Motion of the Hip

BackgroundMany factors have been reported to affect postoperative range of knee flexion after total knee arthroplasty (TKA); however, no study has reported the impact of preoperative range of motion of the hip to the postoperative flexion angle of the knee thus far.MethodsOf 38 consecutive patients who underwent posterior-stabilized TKA, we assessed 21 patients after excluding 17 patients who met exclusion criteria. The range of motion of the knee and the hip, age, body-mass index, serum albumin level, HbA1c, Kellgren–Lawrence grade, knee extension strength and radiological femorotibial angle as well as postoperative knee flexion angle at three months were evaluated. The preoperative data and the knee flexion angle at three months after TKA were compared using Spearman''s rank correlation coefficient.ResultsKnee flexion angle at three months after TKA was positively correlated with preoperative flexion (ρ = 0.616, p = 0.007) and external rotation angle (ρ = 0.576, p = 0.012) of the hip as well as preoperative knee flexion angle (ρ = 0.797, p = 0.001). There were no correlations between postoperative knee flexion angle and other preoperative data.ConclusionsPatients with restricted flexion and/or external rotation of the hip may have contractures of Gluteus maximus, Gluteus medius and Tensor fasciae latae, which can cause hypertension of iliotibial tract. It may cause decreased internal rotation of the tibia when the knee is flexed, which affects postoperative knee flexion angle, thus limited flexion and/or external rotation of the hip might restrict knee flexion angle following TKA.     

Factors affecting range of flexion after total knee arthroplasty

Many factors affect postoperative range of flexion after total knee arthroplasty (TKA). The purpose of this study was to identify the most important factors that affect range of knee flexion after TKA. Sixty-five patients (73 knees) were treated with Genesis II knee replacements. Minimum follow-up was 2 years. Patient demographics (sex, age, body mass index, previous surgery, component type, patella resurfacing, preoperative Knee Society score preoperative range of motion) and radiographic measurements (preoperative tibiofemoral varus/valgus angle, height of the joint line, length of the patellar tendon, shift and tilt angle of the patella) were analyzed statistically. Among these factors, preoperative range of flexion, positively, and preoperative varus/valgus tibiofemoral angle, negatively, affected postoperative range of flexion. The tilt angle of the patella and the tilt angle of the patellar button approached statistical significance in revealing a negative relation with postoperative range of flexion. TKAs in which the patella was not resurfaced tended to lose range of flexion, whereas TKAs in which the patella was resurfaced tended to have no loss of flexion, although the number of TKAs in which the patella was not resurfaced was small. In conclusion, preoperative range of flexion and preoperative varus/valgus tibiofemoral angle affected postoperative range of flexion. The tilt angle of the patella and tilt angle of the patellar button may be factors that affect postoperative range of flexion. Received: September 28, 2000 / Accepted: January 9, 2001     

旋转平台与固定平台全膝关节置换术的对比研究及髌骨置换与否对疗效的影响

目的评估旋转平台和固定平台假体全膝关节置换(TKA)两型假体间的疗效有无差异及髌骨置换与否对疗效的影响。方法选取同一医师施行的78侧初次TKA进行回顾。术前诊断包括骨关节炎、类风湿性关节炎等。施行固定平台TKA手术的患者共30侧,14侧置换髌骨;施行旋转平台TKA手术的共48侧,36侧置换髌骨。术前和术后随访行膝HSS评分、测量关节伸直角度和屈曲角度,以比较两型假体TKA疗效;比较髌骨置换组与未置换组TKA疗效;在髌骨置换组与未置换组中,分别比较固定平台TKA和旋转平台TKA的疗效。结果成功随访76侧,平均25.2个月。旋转平台组术后HSS评分、伸直角度与固定平台组间的差异无统计学意义,前者术后的屈曲角度(112.0±11.5)°优于固定平台组间的差异有统计学意义(t=3.270,P0.01)。髌骨未置换组术后HSS评分、伸直角度与髌骨置换组(102.5±15.1)°组间差异有统计学意义(t=2.469,P0.05;t=3.747,P0.01),术后屈曲角度与后者间的差别无统计学意义。髌骨未置换组中,旋转平台TKA与固定平台TKA的术后HSS评分、屈曲角度无差异,伸直角度差别无临床意义。髌骨置换组中,旋转平台TKA术后HSS评分、伸直角度与固定平台TKA间的差异无统计学意义,前者术后的屈曲角度(112.9±13.0)°与后者术后的屈曲角度(96.7±18.4)°比较差异有统计学意义(t=2.838,P0.05)。结论旋转平台假体与固定平台假体TKA术后总体疗效相似,旋转平台假体能够更好地改善关节屈曲角度;置换髌骨并不能更好地改善膝关节功能。     

Intraoperative loose flexion gap may restrict postoperative knee flexion after J-curve design posterior-stabilized total knee arthroplasty

Introduction

Although soft tissue tension during total knee arthroplasty (TKA) has been targeted to achieve equal flexion and extension gaps, such a perfect gap is not always obtained. This study was performed to investigate the impact of difference between flexion and extension gaps on postoperative knee flexion angle.

Materials and methods

We reviewed 107 consecutive TKAs using a J-curve design posterior-stabilized prosthesis. Soft tissue tension was measured intraoperatively using an offset-type tensor under 30 lb force of joint distraction with the patella reduced. All TKAs were performed in a uniform manner including the subvastus approach and without use of a pneumatic tourniquet. We assessed the association between knee flexion angle 1 year after TKA and the difference between flexion and extension gaps using Pearson’s product-moment correlation and multiple regression analysis with age, sex, body mass index, diagnosis, history of diabetes mellitus, preoperative flexion angle, and gap difference as explanatory variables.

Results

The difference between flexion and extension gaps showed a slight negative correlation with postoperative knee flexion angle in univariate analysis (r = − 0.20, 95% CI, − 0.38 to − 0.01, p = 0.04). Multiple regression analysis showed that the gap difference was an independent factor associated with postoperative knee flexion angle (β = − 0.89, 95% CI, − 1.60 to − 0.18, p = 0.01).

Conclusions

The difference between flexion and extension gaps was negatively correlated with postoperative knee flexion angle. Looser flexion gap compared with extension gap should be avoided in J-curve design posterior-stabilized TKA.

     

人工全膝关节置换术治疗膝关节伸直位强直畸形

目的探讨膝关节伸直位强直畸形患者行人工全膝关节置换术的手术要点和术后效果。方法1996年1月至2006年6月,对8例（9膝）膝关节伸直位强直畸形患者行人工全膝关节置换术。术前膝关节活动度均为0°,KSS膝关节评分平均为44分（10～68分）,功能评分平均为17分（-10～55分）。结果8例患者（9膝）围手术期出现的并发症包括髌腱止点撕脱1膝,髌骨下极部分撕脱骨折1膝,术后早期关节血肿1膝,皮肤浅表性感染1膝,经对症治疗后所有患者均治愈出院。术后平均随访40．4个月（7．0～120．0个月）,术后膝关节平均活动度89°（50°～120°）,术后KSS膝关节评分平均为81分（55～93分）,功能评分平均为79分（50～90分）。2例2膝分别存在5°和25°的伸展滞缺。1例1膝因为关节不稳于术后1年行翻修术,更换加厚的胫骨平台垫片。结论膝关节伸直位强直畸形患者行人工全膝关节置换术难度大,并发症发生率较高,但如能恰当处理,仍可以取得较满意的临床效果。术中膝关节的充分暴露,保留足够的髌骨床厚度,保护髌腱和膝关节的血液供应以及正确的软组织平衡技术是手术的关键。     

Preoperative physical therapy in primary total knee arthroplasty

In order to evaluate the efficacy of preoperative physical therapy for patients undergoing elective primary total knee arthroplasty, 10 patients completed 6 weeks of physical therapy before surgery (PT group). Ten patients served as controls (C group). Subjects were tested at baseline (PT only), before surgery, 6 weeks after surgery, and 3 months after surgery using the Hospital for Special Surgery knee rating scale, range of motion, thigh circumference, walking speed, Cybex II isokinetic knee flexion, and extension testing, and computed tomography scanning for cross-sectional muscle area. Hospital stay and need for physical therapy after inpatient rehabilitation were also compared. Physical therapy produced modest gains in isokinetic flexion strength in these severely arthritic knees but no difference in extension strength. The decrease in isokinetic strength after surgery was not affected by preoperative physical therapy. Muscle area did not decrease significantly for the PT group, but it did decrease for the C group after surgery. While postoperative strength differences could not be demonstrated, preoperative physical therapy preserved thigh muscle area after surgery. The clinical significance of this finding is uncertain. Consequently, this study failed to support the routine use of preoperative physical therapy in knee replacement surgery.     

全膝关节置换术后患肢不同体位对术后出血的影响研究

目的探讨减少全膝关节置换（TKA）术后出血的相对更有效的患肢体位。方法按随机数字表法将2010/9/5至2012/7/15入住本组并符合试验要求的患者分三组。A组（68例）：患肢髋关节及膝关节伸直位;B组（65例）：患肢髋关节屈曲抬高45°,膝关节屈曲70°;C组（73例）：患肢髋关节屈曲抬高45°,膝关节伸直位。试验干预于术后12h终止,术后3组均放置负压引流袋24h,比较各组24h引流量及手术前后的血红蛋白（Hb）差值,并对比术后5天膝关节活动度。结果术后24h引流量：A组为（424.76±59.11）ml,B组为（403.71±56.26）ml,C组为（404.15±51.89）ml,三组间差异有统计学意义（P〈0.05）;A组分别与B、C组比较,差异均有统计学意义（P〈0.05）;B、C两组间差异无统计学意义（P〉0.05）。手术前后Hb差值：A组为（33.09±7.03）g/L,B组为（29.92±5.33）g/L,C组为（30.68±6.28）g/L,三组间差异有统计学意义（P〈0.05）;A组分别与B、C组比较,差异均有统计学意义（P〈0.05）;B、C两组间差异无统计学意义（P〉0.05）。三组术后5d膝关节活动度差异比较无统计学意义（P〉0.05）。B组术后4d发生深静脉血栓1例。结论屈髋位与髋关节伸直位相比可减少TKA术后出血量;相同屈髋角度时,屈膝70°位和直腿抬高位对减少TKA术后出血的作用相同。同时鉴于大角度屈膝时对切口的不良影响,作者推荐术后将患肢直腿抬高以减少TKA术后出血。     

Heterotopic ossification following primary total knee arthroplasty

Ninety-eight consecutive primary total knee arthroplasties (TKAs) in 70 patients were retrospectively evaluated for heterotopic ossification (HO). A radiographic classification was devised based on the extent and location of the ectopic bone. Twenty-five knees (26%) in 19 patients developed HO. Eight of 11 patients (73%) with preexisting heterotopic bone at other sites developed HO in the index knee. Multivariate analysis demonstrated that advanced HO was associated with restricted knee motion. Eight knees with advanced HO had a mean 14° decrease in postoperative, as compared with preoperative, knee flexion (P < .05). For all patients with HO, mean lumbar spine bone mineral density (BMD) was significantly elevated compared with a matched control group not developing HO (P < .05). Heterotopic ossification following primary TKA correlates with a limitation of postoperative knee flexion and is predicted by increased lumbar BMD. Preoperative measurement of spinal BMD may identify those patients at risk for HO and allow for the institution of preoperative prophylaxis and modification of postoperative rehabilitation to optimize functional outcome following TKA.     

增加胫骨平台后倾角度、后交叉韧带部分松解对全膝关节置换术后膝关节运动影响的实验研究

目的通过增加胫骨平台后倾角度或后交叉韧带（PCL）部分松解对全膝关节置换术（TKA）中屈曲间隙过紧进行处理,分析这两种方法对TKA术后膝关节运动学的影响。方法测量6例新鲜尸体膝关节标本在完整状态下、正常TKA、屈曲间隙过紧、增加胫骨平台后倾角以及PCL部分松解TKA术后膝关节屈曲0°、30°、60°、90°、120°时的前后松弛度、内外翻松弛度、旋转松弛度及最大屈曲度。结果屈曲过紧TKA与正常TKA相比,在屈曲30°、60°、90°和120°时前后松弛度、内外翻松弛度及旋转松弛度均显著较小（P〈0．05）。与屈曲过紧TKA相比,增加胫骨后倾角后,在屈曲30°、60°、90°和120°时前后松弛度、内外翻松弛度和旋转松弛度均明显增大（P〈0．05）。PCL部分松解与屈曲过紧TKA相比,在屈曲30°、60°、90°和120°时前后松弛度明显增加（P〈0．05）;旋转松弛度在屈曲30°、60°、90°时明显增加（P〈0．05）。与PCL部分松解相比,增加胫骨后倾角的内外翻松弛度在屈曲30°、60°、90°时明显较大（P〈0．05）;旋转松弛度在屈曲0°、30°、60°和90°时明显较大（P〈0．05）。屈曲过紧TKA的最大屈曲度（120．4°）与正常TKA（130．3°）及增加胫骨后倾角（131．1°）相比明显较小（P〈0．05）。增加后倾角与PCL部分松解（124．0°）相比,最大屈曲度较大,但差异无统计学意义（P=0．0816）。结论屈曲间隙过紧TKA术后膝关节的前后松弛度、内外翻松弛度、旋转松弛度和最大屈曲度均减小;增加胫骨平台后倾角后,前后松弛度、内外翻松弛度、旋转松弛度和最大屈曲度均明显增大;PCL部分松解仅能明显增大前后松弛度。因此对于TKA术中屈曲紧张的膝关节,增加胫骨平台后倾角比PCL部分松解能更好地改善膝关节的运动学。     

The role of flexion contracture on outcomes in primary total knee arthroplasty

This study examined the role that flexion contracture plays in postoperative outcomes after total knee arthroplasty using a retrospective database review. The relationships between preoperative and postoperative knee extension, walking ability, stair climbing ability, Knee Society scores, pain scores, and knee function scores were studied in 5,622 knees. A preoperative flexion contracture was associated with an increased incidence of a persistent postoperative flexion deformity. A postoperative flexion contracture was associated with poorer postoperative results. Furthermore, a postoperative hyperextension deformity of greater than 10 degrees was associated with an increased risk of suboptimal pain and Knee Society scores. Knee extension deformities play a substantial detrimental role in the functional outcome of primary total knee arthroplasty.     

Innex膝关节假体置换术后活动度与假体设计及手术技术的关系

目的 探讨Innex膝关节假体置换术后膝关节活动度与假体设计及手术技术的关系.方法 2003年9月至2005年12月使用CS型Innex假体行全膝关节置换88例(98膝),均患膝关节骨关节炎,体重指数20～30 kg/m2,内外翻畸形、屈曲畸形＜15°,为初次全膝关节置换并使用相同的手术技术.随访63例(70膝),随访时间4～6年,平均5.3年.分析活动度与股骨后髁偏心距和胫骨平台后倾角的相关性.根据术后、术前股骨后髁偏心距的差值大小将患者分为:1组,＜-2 mm;2组,-2～0 mm;3组,0～2 mm,4组,＞2 mm.分析各组术前体重指数、屈曲畸形、活动度、特种外科医院膝关节评分及术后活动度的差异.结果 随访患者术前膝关节活动度平均96.2°±11.9°,末次随访时平均109.8°±13.0°;术前股骨后髁偏心距平均(24.0±3.5)mm,术后平均(24.5±3.3)mm;术后胫骨平台后倾角平均5.5°±1.8°.膝关节活动度的差值与股骨后髁偏心距的差值相关,术后膝关节活动度与术后胫骨平台后倾角不相关.四组患者术前体重指数、屈曲畸形、活动度、特种外科医院膝关节评分差异无统计学意义,而术后活动度的差异有统计学意义.结论 Innex膝关节假体置换术后膝关节活动度良好.术中行股骨后方截骨时需注意恢复股骨后髁偏心距,以增加术后活动度.术后膝关节活动度与胫骨平台后倾角无关.

Abstract：

Objective To analysis the influence of component design and related surgical technique on knee range of motion (ROM) after total knee replacement using Innex knee system. Methods Between September 2003 and December 2005, 88 patients with 98 knees had consecutively undergone posterior cruciate-sacrificing TKA with Innex systems. The posterior condylar offset, post-operative tibial slope and knee ROM were measured in 63 patients (70 knees). The relationship of the change in posterior condylar offset and postoperative tibial slope with knee ROM was assessed using a scatterplot graph and Pearson's regression analysis. According to change of posterior condylar offset, which was measured by postoperative minus preoperative posterior condylar offset, patients were divided into 4 groups. The preoperative body mass index,flexion contracture, knee ROM, HSS score and the postoperative knee ROM of four groups were evaluated.Results The mean knee ROM had improved from 96.2°±11.9° preoperative to 109.8°±13.0° at final followup. The mean pre- and post-operative posterior condylar offset was (24.0±3.5) mm and (24.5±3.3) mm, respectively. The mean postoperative tibial slope was 5.5°±1.8°. There was statistical correlation between the difference in the posterior condylar offset and the change in knee ROM after TKA and no correlation between the postoperative tibial slope and knee ROM postoperatively. The preoperative body mass index, flexion contracture, knee ROM, HSS score did not show difference among four groups. There was a statistically difference in postoperative knee ROM among groups. Conclusion Restoration of posterior condylar offset is important to the maximum range of postoperative knee ROM when Orthopedic surgeons perform TKA with Innex systems.There was no correlation between the postoperative tibial slope and postoperative ROM.     

Association of increased knee flexion and patella clunk syndrome after mini-subvastus total knee arthroplasty

This study reviewed 747 consecutive posterior stabilized total knee arthroplasty (TKA) to explain the increased incidence of patella clunk syndrome that occurred when the surgeon switched from a medial parapatellar arthrotomy to a mini-subvastus (MIS) TKA technique. The incidence of patella clunk syndrome increased with increased postoperative knee flexion. Six weeks after surgery, knees that developed patella clunk had a mean flexion of 124 degrees vs 117 degrees for knees that did not develop this syndrome (P = .016). As the MIS approach resulted in increased knee flexion, this approach was indirectly associated with the increased incidence of patella clunk. Knee flexion at 6 weeks postoperatively was 117 degrees for the MIS knees vs 108 degrees for traditional medial parapatellar arthrotomy knees (P < .001). The effect of increased knee flexion achieved with the MIS approach, which resulted in an increase in patella clunk, was mitigated by using a new posterior stabilized femoral component designed to minimize soft tissue entrapment.     

Posterior condylar offset and flexion in posterior cruciate-retaining and posterior stabilized TKA

Background Anterior tibial translation associated with posterior impingement has been reported to be one of the factors limiting flexion after posterior cruciate-retaining (CR) total knee arthroplasty (TKA), especially when posterior condylar offset is decreased postoperatively. On the other hand, its effect on postoperative motion in posterior-stabilized (PS) TKA remains unknown. It has been demonstrated that PS TKA exhibits a consistent posterior femoral rollback during flexion. Thus, we hypothesized that the problem of posterior impingement can be avoided by use of PS TKA. In this study, we examined the relationship between postoperative posterior condylar offset and knee flexion in CR and PS TKAs. Methods In this study, analysis was performed for 20 subjects who underwent bilateral TKAs (one CR and one PS TKA) as well as another group of 50 PS TKAs. All patients could be tracked for a minimum of 2 years. The range of flexion was measured before operation and at follow-up. Preoperative and postoperative posterior condylar offset was evaluated on true lateral radiographs. Results At the follow-up examination, the mean flexion angle was 123° in the CR knees and 131° in the PS knees with a significantly greater improvement observed for the latter group. In the roentgenographic measurement of the posterior condylar offset, no significant difference was observed between the preoperative and postoperative values both in the CR and PS knees. We divided the patients into two groups according to the change of posterior condylar offset. The first group (Group I) showed a decrease in the posterior condylar offset after surgery and the second group (Group II) showed no change or an increase. Subsequently, postoperative change in flexion was compared between Groups I and II for the CR and PS knees. A significant difference between Groups I and II was observed in the CR knees, while no difference was observed in the PS knees. The magnitude of postoperative posterior condylar offset did not correlate with an improvement in maximum flexion angle in the 50 PS knees. Conclusions It was shown that the magnitude of posterior condylar offset correlated with a postoperative change in flexion angle in CR knees, while no such correlation was observed in PS knees.     

Total knee arthroplasty in bony ankylosis in gross flexion

Between June 1993 and December 1994, we performed total knee arthroplasty (TKA) on 27 knees in 24 patients with spontaneous bony ankylosis in severe flexion. The mean age at operation was 43.5 years (30 to 60). No patient had preoperative pain. Three were unable to walk and 21 could manage less than five blocks. The mean duration of the ankylosis was 18.7 years (13 to 25) and its mean position was 105 degree flexion (75 to 135). The preoperative Hospital for Special Surgery Knee Score of 60 points was improved to 87 at the final follow-up three to five years later. All knees were free from pain. The mean range of active flexion in 24 knees was 97 degrees (78 to 115) and the mean arc of movement 91 degrees (78 to 98). The mean fixed flexion deformity was 6 degrees (0 to 25) and the extension lag 8 degrees (0 to 25). Angular deformity was corrected to between 0 degrees and 10 degrees of valgus. Four patients were able to walk one block and 20 five to seven blocks. Thirteen knees (48%) showed some necrosis at the skin edge; one knee required arthrodesis and another resection arthroplasty. One had a recurrence of tuberculous infection requiring arthrodesis. One patient had a rupture of the quadriceps tendon. To date no prosthesis has required revision for loosening. Radiolucency of 1 mm or less about the tibial prosthesis was observed at follow-up in four of the 24 knees. Our results have shown that one-stage TKA and skeletal traction after operation can achieve correction of severe flexion deformity of the knee with marked improvement in the function and quality of life.     

人工全膝关节置换术治疗终末期膝关节病变合并膝外翻畸形的手术技巧及临床疗效评价

目的探讨对终末期膝关节病变合并膝外翻畸形患者行经髌旁内侧入路人工全膝关节置换(total kneearthroplasty,TKA)时膝外翻畸形矫正方法及临床疗效。方法 1998年11月-2010年10月,收治64例72膝合并膝外翻畸形的终末期膝关节病变患者。男18例,女46例;年龄23～82岁,平均62.5岁。骨关节炎44例49膝,类风湿性关节炎17例20膝,血友病性关节炎2例2膝,创伤性关节炎1例1膝。双膝8例,单膝56例。膝关节屈伸活动度为(82.2±28.7)°,X线片测量股胫角为(18.0±5.8)°。膝关节学会评分系统(KSS)临床评分为(31.2±10.1)分,功能评分(37.3±9.0)分。根据Krackow膝外翻分型标准:Ⅰ型65膝,Ⅱ型7膝。手术经髌旁内侧入路,采用常规方法行股骨及胫骨截骨,Ranawat技术进行软组织松解。6例7膝采用保留后交叉韧带型假体,54例60膝采用后稳定型假体,4例5膝采用髁限制型假体。结果术后患者切口均Ⅰ期愈合。1例血友病性关节炎合并严重膝外翻畸形(股胫角41°)、屈曲挛缩20°的患者术后出现腓总神经麻痹,经保守治疗1年后神经功能恢复。1例术后2年发生深部感染,行二期翻修术后治愈。患者术后均获随访,随访时间1～13年,平均4.9年。末次随访时X线片示股胫角为(7.0±2.5)°,与术前比较差异有统计学意义(t=15.502,P=0.000)。KSS临床评分为(83.0±6.6)分,功能评分(85.1±10.5)分,膝关节屈伸活动度为(106.1±17.0)°,与术前比较差异均有统计学意义(P0.05)。5例遗留12～15°膝外翻畸形,但患膝关节功能良好。结论通过恰当的术中截骨和软组织平衡,采用经髌旁内侧入路TKA治疗合并膝外翻畸形的终末期膝关节病变可有效改善膝外翻畸形和恢复关节功能,临床疗效满意。     

胫骨后倾截骨对后十字韧带保留型全膝关节置换术疗效的影响

目的 探讨胫骨后倾截骨对后十字韧带保留型全膝关节置换术后临床疗效的影响.方法 2008年1月至2009年3月应用胫骨后倾5°截骨(后倾组)进行后十字韧带保留型全膝关节置换治疗骨关节炎患者27例(27膝),男7例7膝,女20例20膝;平均年龄69.5岁.同期应用胫骨后倾0°截骨(非后倾组)57例57膝,男15例15膝,女42例42膝;平均年龄67.4岁.两组患者术前一般资料、膝关节最大伸直角度、最大屈曲角度和美国膝关节协会评分(knee society score,KSS评分)差异均无统计学意义.比较术后两组胫骨后倾角、关节最大伸直角度、最大屈曲角度和KSS评分的差异.结果 所有患者均获随访12～24个月,平均(15.7±4.3)个月.未发生腓总神经损伤、伤口感染、假体脱位、假体松动等并发症.后倾组术后胫骨后倾角5.7°±2.1°,非后倾组0.9°±0.6°.后倾组术后关节最大伸直角度0.8°±0.3°,非后倾组1.2°±0.4°,差异无统计学意义.后倾组术后关节最大屈曲角度115.7°±4.8°,非后倾组101.1°±5.6°,差异有统计学意义.后倾组术后KSS评分(87.6±5.9)分,非后倾组(83.3±7.2)分,差异无统计学意义.结论 在后十字韧带保留型全膝关节置换术中胫骨后倾截骨可以增加术后关节最大屈曲角度,但对最大伸直角度和KSS评分无明显影响.