Factors Correlated with the Reducibility of Varus Deformity in Knee Osteoarthritis: An Analysis Using Navigation Guided TKA

Background

We hypothesized that a number of clinical and radiologic parameters could influence the reducibility of varus deformity in total knee arthroplasty. The aim of this study was to identify the factors correlated with reducibility of varus deformity and predict more accurately the amount of medial soft tissue release required in varus deformity total knee arthroplasty.

Methods

One hundred forty-three knees with preoperative varus alignment and medial osteoarthritis were included in this retrospective study. The total knee arthroplasties were performed using a navigation system (OrthoPilot) by single surgeon. To assess varus deformity, the authors measured preoperative mechanical axis angles and valgus stress angles. Mechanical tibial angles, mechanical femoral angles, femoral osteophyte sizes, and tibial osteophyte sizes were measured. The Ahlbäck grading scale was applied for radiologic parameters, and clinical parameters (age, body mass index, sex, duration of pain, and preoperative range of motion) were documented. Correlations between these factors and preoperative valgus stress angle were analyzed.

Results

A negative correlation was found between preoperative mechanical axis angle and preoperative valgus stress angle (p < 0.01, r = -0.38), and a positive correlation was found between the preoperative mechanical tibial angle and preoperative valgus stress angle (p = 0.01, r = 0.19).

Conclusions

The present study shows that preoperative varus deformity and proximal tibial vara (measured by preoperative mechanical axis angle and mechanical tibial angle, respectively) are correlated with reducibility of varus deformity (measured by preoperative valgus stress angle), and clinical parameters (age, range of motion, duration of pain and body mass index) and other radiologic parameters (osteophyte size, severity of osteoarthritis and angulation of distal femoral joint surface) were not significantly correlated with reducibility of varus deformity.     

全膝关节置换术中股骨内髁滑移截骨治疗伴有关节外畸形的膝内翻

目的：探讨股骨内髁滑移截骨术（medial condyle sliding osteotomy, MCSO）在全膝关节置换术中纠正患者内翻膝关节外畸形的临床疗效。方法通过回顾性研究2013年1月至2015年12月在第三军医大学附属西南医院关节外科中心于全膝关节置换术中采用MCSO在关节内纠正股骨侧的关节外内翻畸形的12例患者,统计该组患者手术前后的股骨远端外侧力线角（mechanical lateral distal femoral angle, mLDFA）、髋-膝-踝（hip?knee?ankle, HKA）角、疼痛视觉模拟量表（visual analogue scale, VAS）评分及美国膝关节协会（American Knee Society, AKS）综合评分系统中的膝评分和功能评分等,评价MCSO纠正关节外的内翻畸形的效果。结果本组患者随访6~40个月,无感染、骨折、假体松动、截骨不愈合等并发症发生。本组患者手术前后的mLDFA分别为117.4°±4.7°、91.6°±1.4°;手术前后的HKA角分别为167.2°±9.8°、179.6°±1.6°;手术前后的VAS评分分别为（6.4±1.1）分、（1.8±1.5）分;手术前后的AKS膝评分分别为（60.2±17.6）分、（92.6±9.4）分;手术前后的AKS功能评分分别为（69.4±21.3）分、（87.6±14.9）分。手术前后以上指标的差异均有统计学意义（均P＜0.05）。结论在合并关节外畸形的内翻膝的关节置换手术中,采用MCSO技术可以正确纠正内翻力线,更容易实现伸屈间隙平衡,达到满意的手术疗效。能有效避免对膝关节后内侧和内侧组织结构的过度松解,从而避免单纯依赖软组织松解而导致的屈曲位内侧间隙松弛及髌股关节对位不良等问题。     

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。     

Flexion Space Balancing Through Component Positioning and Its Relationship to Traditional Anatomic Rotational Landmarks in Robotic Total Knee Arthroplasty

BackgroundThe use of the femoral component position to balance the flexion space and its relationship to the transepicondylar axis (TEA) and posterior condylar angle (PCA) has not been thoroughly evaluated.MethodsA total of 233 patients undergoing robotic arm–assisted total knee arthroplasty were evaluated. Native TEA and PCA were established on preoperative computed tomography scans. Femoral component rotation was set in the axial plane to match the native trochlea and native medial femoral condyle to set the flexion gap. Knee flexion space gaps and component position were recorded. The relationship of the femoral component to the native TEA, PCA, and preoperative radiographic landmarks was evaluated.ResultsThe intraoperative measured medial flexion space gap did not significantly correlate with the relationship of the femoral component to the PCA or TEA in varus or valgus knees. In varus knees, the preoperative mechanical axis alignment had a positive relationship to femoral component position when compared to the PCA (P = .04) and TEA (P = .002). In valgus knees, there was a positive correlation between the preoperative lateral distal femoral angle and component position when compared to the PCA (P = .04) only.ConclusionIntraoperative measured flexion space balance through femoral component positioning did not correlate with its relationship to the native TEA or PCA. In varus knees, the preoperative mechanical axis alignment correlated with an increase in femoral component external rotation to the TEA and PCA. In valgus knees, the severity of preoperative lateral distal femoral angle correlated with the rotational relationship of the femoral component to the PCA only.     

Computer-assisted total knee replacement in patients with arthritis and a recurvatum deformity

We retrospectively reviewed the records of 1150 computer-assisted total knee replacements and analysed the clinical and radiological outcomes of 45 knees that had arthritis with a pre-operative recurvatum deformity. The mean pre-operative hyperextension deformity of 11° (6° to 15°), as measured by navigation at the start of the operation, improved to a mean flexion deformity of 3.1° (0° to 7°) post-operatively. A total of 41 knees (91%) were managed using inserts ≤ 12.5 mm thick, and none had mediolateral laxity > 2 mm from a mechanical axis of 0° at the end of the surgery. At a mean follow-up of 26.4 months (13 to 48) there was significant improvement in the mean Knee Society, Oxford knee and Western Ontario and McMaster Universities Osteoarthritis Index scores compared with the pre-operative values. The mean knee flexion improved from 105° (80° to 125°) pre-operatively to 131° (120° to 145°), and none of the limbs had recurrent recurvatum. These early results show that total knee replacement using computer navigation and an algorithmic approach for arthritic knees with a recurvatum deformity can give excellent radiological and functional outcomes without recurrent deformity.     

Varus Gonarthrosis Predisposes to Varus Malalignment in TKA

Postoperative alignment is a predictor for long-term survival of total knee arthroplasty (TKA). The purpose of this study was to evaluate whether or not preoperative deformities predispose to intraoperative malposition of TKA components. A retrospective radiographic analysis of 53 primary TKA cases was performed. Preoperative AP hip to ankle and lateral knee radiographs were compared with postoperative views to evaluate component positioning. The following angles were measured: the hip–knee–ankle (HKA) angle expressing the mechanical axis of the leg, the mechanical lateral distal femur angle (mLDFA), the medial proximal tibia angle (MPTA), the posterior distal femur angle (PDFA), and the posterior proximal tibia angle (PPTA). Postoperative measurement of the HKA revealed 34.0% of the cases had a deviation of >±3° from neutral alignment. Sixteen knees (30.2%) were in varus and, with one exception, all presented with severe varus gonarthrosis prior to surgery with a mean tibiofemoral angle of 12.4° compared with 1.0° of valgus in the optimally aligned group. Patients (93.3%) with preoperative valgus malalignment showed optimal postoperative HKA. Odds ratios for malalignment of TKA for varus knees in comparison with valgus knees were 7.1 for HKA, 2.4 for MPTA, 4.9 for PDFA, and 1.7 for PPTA. The overall number of outliers in the presented data corresponds well with reports from other authors using different implants and guide systems. The presented data indicate that patients with preoperative varus alignment have a higher risk of postoperative implant malposition than patients with valgus alignment. The data supports that preoperative varus deformity predisposes to varus malposition of TKA. The risk for intraoperative malposition is significantly lower in valgus knees.     

Distal femoral cut perpendicular to the mechanical axis may induce varus instability in flexion in medial osteoarthritic knees with varus deformity in total knee arthroplasty: a pitfall of the navigation system

Two factors that influence the external rotation angle of the femoral rotational axis in total knee arthroplasty (TKA) were assessed in 40 medial osteoarthritic knees with varus deformity. First, the anatomic configuration of the femur was assessed using standardized radiographs of the patients lower extremities before TKA. Second, the degree of medial soft tissue release was assessed during TKA. The radiographs showed that the characteristics of the femur were lateral bowing of the shaft and external rotation of the condyle in the coronal plane. Therefore, when the distal femur is cut perpendicular to the mechanical axis, the cut surface may be in too much of a valgus position. Furthermore, some degree of medial soft tissue release was necessary in all knees. Medial soft tissue release rotates the femur externally in extension in the coronal plane, and it rotates the femur externally around the femoral axis in flexion relative to the tibia. A distal femoral cut in too much of a valgus position and medial soft tissue release induces varus instability in flexion in knees with lateral bowing of the femoral shaft. Anatomic variation such as femoral bowing should be considered when a navigation system is used for TKA because the navigation system shows only the mechanical axis.     

高屈曲度人工全膝关节置换术的临床疗效

目的 探讨影响人工全膝关节置换术患者术后屈膝的因素,以及获得相对最大屈曲度的技术.方法 自2002年3月至2007年3月,85例患者102膝行高屈曲度人工全膝关节置换术(LPS-Flex knee arthroplasty,LF-KA),男16例17膝,女69例85膝;年龄35～79岁,平均64.9岁.膝关节骨关节炎94膝,类风湿关节炎8膝.膝内翻畸形82膝(平均12.8°±3.1°),膝外翻畸形7膝(平均5.1°±2.4°),屈曲畸形31膝(平均15.6°±4.9°).骨缺损5膝.膝关节骨关节炎患者术前活动度为61°～135°,平均110.5°;类风湿关节炎患者为41°～120.,平均85.5°.手术均采用NexGen,LPS-Flex假体.临床疗效以HSS评分为标准,根据影像学资料评估膝关节假体位置、下肢力线以及骨缺损修复情况.结果 66例81膝随访24～60个月,平均39个月.术前HSS平均(69.6±7.4)分,术后平均(90.9±4.8)分.优64膝,良11膝,中4膝,差2膝,优良率为92.6%.膝关节活动度由术前平均100.5°,改善至术中平均136.8°,终末随访时平均127.5°.结论 膝关节活动度的改善对满足患者的日常生活需要尤为重要.患者术前活动度、手术技术、特殊的假体设计以及积极的术后锻炼都是实现全膝关节置换术后最大屈曲度的重要因素.但肥胖、有膝关节手术史、强直性脊柱炎等患者,人工全膝关节置换术后的活动度都会受到一定的限制.     

The relationship between postoperative ligament balance and preoperative varus deformity in total knee arthroplasty.

We hypothesize that in knees with severe varus deformities, varus-valgus ligament imbalance tends to remain postoperatively after total knee arthroplasty. The purpose of this study was to evaluate the correlation between preoperative varus deformity and postoperative ligament balance quantitatively measured by stress radiograph using Telos SE in total knee arthroplasty. In this study, 44 knee arthroplasties in 32 patients were evaluated. We defined the angle in varus and valgus stress as "varus angle" and "valgus angle," and the sum of varus angle and valgus angle as "sum of varus-valgus angle." There was a significant correlation between preoperative lateral femoral angle and varus angle (p < 0.0001, r = 0.56), which means that postoperative ligament imbalance tends to remain in knees with preoperative varus deformities. There was a significant correlation between the postoperative period and the sum of varus-valgus angle, which suggests that knees with total knee arthroplasty have potential to increase laxity postoperatively.     

膝关节内侧固定平台单髁假体放置位置优化的有限元分析

目的探讨股骨组件及胫骨组件冠状面位置变化对股骨及胫骨生物力学的影响。方法取1名汉族男性志愿者的左侧膝关节CT及MRI图像,建立正常膝关节三维有限元模型(finite elemental model,FEM)。设计股骨组件及胫骨组件内翻6°、内翻3°、0°、外翻3°、外翻6°,组合成25个膝内侧单髁置换FEM。沿股骨机械轴加载1000 N载荷,观察von Mises云图应力分布,测量外侧间室载荷比例,测量胫骨组件下方松质骨及内侧皮质骨、聚乙烯衬垫上表面、外侧间室股骨软骨高接触应力值。将与中立位(胫骨及股骨假体内外翻0°、胫骨假体后倾5°)比较有统计学意义的指标通过散点图标识,找出点项目密集区和稀疏区,比较两区有统计学意义的项目数量,确定股骨组件、胫骨组件优化位置。结果股骨组件0°位放置时,胫骨从内翻6°至外翻6°各组合的胫骨组件下方松质骨高接触应力差异无统计学意义;胫骨组件0°位放置时,股骨组件内翻6°、外翻6°组件下方松质骨高接触应力值与中立位比较增加(9.21±3.38)MPa和(9.08±4.13)MPa(P<0.05)。股骨、胫骨组件从内翻6°至外翻6°变化时,胫骨下方内侧皮质骨高接触应力值逐渐下降(P<0.05)。股骨组件0°位放置时,胫骨组件从内翻6°至外翻6°各组合聚乙烯衬垫上表面高接触应力值的差异无统计学意义;胫骨组件0°位放置时,股骨组件内翻6°、外翻6°组与中立位组比较分别增加(2.88±2.53)MPa和(3.47±2.86)MPa(P<0.05);股骨及胫骨组件从内翻6°至外翻6°变化时,外侧间室载荷比例及外侧间室股骨软骨高应力值逐渐下降(P<0.05)。稀疏区(股骨或胫骨从内翻3°至外翻3°的所有组合的集合)有统计学意义的指标比例(2.8%,1/36)明显小于密集区(去除稀疏区以外的所有组合的集合)的比例(57.8%,37/64),差异有统计学意义(χ^2=29.61,P<0.001)。结论在下肢力线正常、关节线不变的条件下,膝关节内侧固定平台单髁假体放置位置为股骨组件、胫骨组件内翻、外翻角度不宜超过3°。     

Utility of Preoperative Distractive Stress Radiograph for Beginners to Extent of Medial Release in Total Knee Arthroplasty

Background

This study evaluated the preoperative distractive stress radiographs in order to quantify and predict the extent of medial release according to the degree of varus deformity in primary total knee arthroplasty.

Methods

We evaluated 120 varus, osteoarthritic knee joints (75 patients). The association of the angle on the distractive stress radiograph with extent of medial release was analyzed. The extent of medial release was classified into the following 4 groups according to the stage: release of the deep medial collateral ligament (group 1), release of the posterior oblique ligament and/or semimembranous tendon (group 2), release of the posterior capsule (group 3) and release of the superficial medial collateral ligament (group 4).

Results

The mean femorotibial angle on the preoperative distractive stress radiograph was valgus 2.4° (group 1), valgus 0.8° (group 2), varus 2.1° (group 3) and varus 2.7° (group 4). The extent of medial release increased with increasing degree of varus deformity seen on the preoperative distractive stress radiograph.

Conclusions

The preoperative distractive stress radiograph was useful for predicting the extent of medial release when performing primary total knee arthroplaty.     

Computer-navigated TKA for the treatment of osteoarthritis associated with extra-articular femoral deformity

The purpose of this study was to evaluate the efficacy of computed-navigated total knee arthroplasty for the treatment of osteoarthritis associated with extra-articular femoral deformity. Between January 2008 and June 2010, twelve patients (12 knees) with osteoarthritis combing extra-articular femoral deformity underwent total knee arthroplasty using the Stryker Navigation System 3.1 (Kalamazoo, Michigan), a wireless and imageless system. Average follow-up was 12.3 ± 8.2 months (range, 3-24 months). Full-length weight-bearing anteroposterior radiographs, knee range of motion, and Knee Society Score were obtained for all patients pre- and postoperatively. The data were analyzed with SPSS version 12.0 statistical software (SPSS, Inc, Chicago, Illinois). Average preoperative overall mechanical axis of the 12 knees was -10.0° ± 4.4° of varus (range, -5° to -18.5°) and average postoperative mechanical axis was -0.9° ± 0.8° (range -2° to 0°). Average Knee Society Score increased from 40.8 ± 7.7 preoperatively to 94.9 ± 2.4 postoperatively, and average function score increased from 39.6 ± 12.3 preoperatively to 95.4 ± 4.0 postoperatively. Average knee range of motion improved from 83.7° ± 18.7° preoperatively to 115.0° ± 8.2° postoperatively. The results of the study showed that computer-navigated total knee arthroplasty may be a valuable option for patients with deformed femurs in which conventional instruments are difficult to use. Follow-up observation of the long-term therapeutic effect of computer-navigated total knee arthroplasty is still needed.     

股骨近段纤维结构不良内翻畸形的手术疗效

目的 评估和分析股骨近段纤维结构不良内翻畸形手术治疗的临床疗效.方法 2000年8月至2009年5月,采用截骨矫形、病灶刮除、打压植骨、股骨重建钉内固定治疗21例(24个)股骨纤维结构不良伴重度内翻畸形患者,男12例,女9例;年龄14～39岁,平均22.7岁.其中15例为单纯髋内翻畸形,6例同时伴髋内翻及股骨内翻畸形.颈干角55°～105°,平均75°;股骨内翻角18°～45°,平均30°;患侧股骨长度较对侧短缩2.0～4.5 cm,平均3.4cm.其中13例患者因发生病理性骨折而行手术治疗.结果 21例患者均获得随访,随访时间21个月至7年,平均3年4个月.24个股骨共30处截骨面中,28处于术后3～6个月骨性愈合,2例双段远端截骨面各有1处在术后12个月时仍不愈合,经再次植骨3个月后骨性愈合.21例内翻畸形股骨力线均完全矫正,术后颈干角矫正为95°～135°,平均118°;股骨内翻角完全纠正.股骨长度较术前延长1.8～3.6 cm,平均2.8cm.术后无一例患者发生感染、畸形进展及再骨折.17例患者疼痛视觉模拟评分(visual analogue scales,VAS)由术前7～10分降至术后0分,4例VAS评分由术前8～10分降至术后3～4分.Harris髋关节功能评分优12例,良6例,可3例.结论 外翻截骨可有效矫正内翻畸形,股骨重建钉可稳定股骨,大量打压式植骨可有效恢复骨量.

Abstract：

Objective To evaluate and analyse the effectiveness of surgical treatment for fibrous dysplasia in proximal femur with severe varus deformity.Methods A retrospective study was performed in 21 patients (24 femora)of fibrous dysplasia who were treated in our hospital between August 2000 and May 2009.All patients had severe femoral varus deformity.The four-step procedures were performed orderlv as valgus osteotomy,lesion curettage,impacting of massive bone allograft,and fixation by femoral intramedullary nail.There were 6 patients with monostotic disease,15 with polyostotic diseases,including 12 males and 9 females with a mean age of 22.7 years(range,14-39 years).The average neck-shaft angle and femoral varus angle was 75°(range 55°-105°)and 30°(range,18°-45°),respectively.The average length of thigh shortened 3.4 cm(range,2.0-4.5 cm)compared with the contralateral thigh.Results All of the 21 patients were followed up from 21 months to 7 years with an average period of 3 years and 4 months.There were 30 osteotomy sites in 24 femurs,28 osteotomy sites showed bone union after 3-6 months from surgery.Two distal location of the double-level osteotomy showed nonunion,which received bone grafting again and got bone union after 3 months finally.The femoral mechanical alignments of the 21 patients had been recriticd.The average neck-shaft angle was 118°(range,95°-135°)postoperatively,the femoral varus angle disappeared.The average extremity lengthening was 2.8 cm(range,1.8-3.6 cm)postoperatively.There were no infection,recurrent fracture and progression of deformity.The visual analogue scales(VAS)score of 17 patients decreased to zero postoperatively from 7-10 preoperatively,and that of the other 4 patients decreased to 3-4 postoperatively from 8-10 preoperatively.The result of Harris hip functional score was excellent in 12 cases,good in 6,and fair in 3.Conclusion The valgus osteotomy can rectify varus deformity effectively.The reconstract nail of the fumer can support the stability of femur.Impacting of massive bone allograft can improve the capacity of the femur.     

Results of total knee arthroplasty with medial epicondylar osteotomy to correct varus deformity.

The clinical results of using medial epicondylar osteotomies to correct varus deformities in total knee arthroplasties were investigated. Unlike the traditional method of subperiosteal stripping of tibial ligaments, this alternative does not damage ligaments. Between 1991 and 1996, the senior author performed medial epicondylar osteotomies in 80 patients (93 knees) with primary total knee arthroplasty; of these, 60 patients (70 knees) were available for 2- to 4-year followup. At followup, no patients reported knee instability. Mean varus and valgus stability measured 14.2 points (Knee Society scale, 0-15 points). The Knee Society clinical score was 93 points, compared with a preoperative score of 42 points. The mean range of motion at followup was 111 degrees, compared with a preoperative mean of 101 degrees. The postoperative tibiofemoral angle on full limb radiographs taken with the patient weightbearing averaged 7 degrees valgus, compared with an average 6 degrees varus preoperative angle. Ninety-five percent of the patients were satisfied and reported less pain and improved knee function. Bone union occurred in 54% of the knees and fibrous union occurred in 46%. Focal tenderness, restricted motion, or other symptoms were not associated with fibrous union. The results show that epicondylar osteotomy for varus knee deformity provides excellent patient satisfaction, knee stability, motion, and deformity correction.     

全膝关节置换术治疗膝关节骨性关节炎的临床观察

目的观察全膝关节置换术（TKA）治疗膝关节骨性关节炎的临床疗效。方法自2012-01—2012-12对50例（59膝）膝关节骨性关节炎行TKA。采用HSS评分标准对手术前后膝关节功能进行评估,并观察有无并发症发生。术后于下肢全长正位X线片上测量机械轴内侧角和股骨假体角（FFC angle）及胫骨假体角（FTC angle）,在侧位X线片上测量股骨假体角（LFC angle）和胫骨假体角（LTC angle）。结果 50例（59膝）均得到平均9（6~12）个月随访。患膝疼痛得到明显缓解或者消失,畸形获得矫正,活动明显改善。末次随访时HSS评分平均（83.66±7.78）分,较术前明显提高。术后X线片均显示假体的位置良好。术后在站立位下肢全长正位X线片上测量机械轴内侧角176°~185°,平均（178±3）°。FFC angle 85°~94°,平均（87±3）°;FTC angle 87°~96°,平均为（90±3）°。LFC angle 78°~89°,平均（85±4）°;LTC angle 77°~95°,平均（87±2）°。结论 TKA可以有效治疗膝关节骨性关节炎,精确测量下肢的力线、恢复膝关节正常的外翻角、注意周围的韧带和软组织的松解平衡是手术的关键。     

微创膝关节单髁置换术股骨髓内定位与髓外定位假体位置的影像学比较

[目的]通过对膝关节单髁置换术股骨假体的力线测量,评价股骨髓外定位法指导假体放置的有效性.[方法]回顾性分析2007年5月～2010年5月采用微创单髁置换术治疗膝关节内侧间室骨性关节炎的患者73例(80膝),其中股骨髓内定位组(intramedullary alignment guide,IM) 54例(56膝),男23例(23膝),女31例(33膝);股骨髓外定位组(extramedullary alignment guide,EM)19例(24膝),男9例(10膝),女10例(14膝).测量术后即刻股骨假体内翻/外翻和屈/伸力线.[结果]IM组股骨假体内翻/外翻力线为0.59°内翻±3.98°,EM组股骨假体力线平均为0.81°外翻±3.30°,P=0.235 2.IM组股骨假体屈/伸力线为0.70°伸直±3.89°,EM组股骨假体力线为1.12°伸直±3.43°,P=0.564 3.[结论]微创膝关节单髁置换术股骨髓内定位可取得与髓外定位法相同优良的股骨假体力线.     

Anatomical analysis of the femoral condyle in normal and osteoarthritic knees.

It is important to understand anatomical feature of the distal femoral condyle for treatment of osteoarthritic knees. Detailed measurement of the femoral condyle geometry, however, has not been available in osteoarthritic knees including valgus deformity. This study evaluated femoral condyle geometry in 30 normal knees, 30 osteoarthritic knees with varus deformity, and 30 osteoarthritic knees with valgus deformity using radiographs and magnetic resonance imaging (MRI). In radiographic analysis in the coronal plane, the femoral joint angle (lateral angle between the femoral anatomic axis and a tangent to femoral condyles) was 83.3 degrees in the normal knees, 83.8 degrees in the varus knees, and 80.7 degrees in the valgus knees. In MRI analysis in the axial plane, the posterior condylar tangent showed 6.4 degrees of internal rotation relative to the transepicondylar axis in the normal knees, 6.1 degrees in the varus knees, and 11.5 degrees in the valgus knees. These results suggested that there was no hypoplasia of the medial condyle in the varus knees, but the lateral condyle in the valgus knees was severely distorted. Surgeons should take this deformity of the lateral femoral condyle into account when total knee arthroplasty is performed for a valgus knee.     

High tibial osteotomy with a dynamic axial fixator: precision in achieving alignment

We report the outcome of 32 patients (37 knees) who underwent hemicallostasis with a dynamic external fixator for osteoarthritis of the medial compartment of the knee. There were 16 men (19 knees) and 16 women (18 knees) with a mean age at operation of 54.6 years (27 to 72). The aim was to achieve a valgus overcorrection of 2° to 8° or mechanical axis at 62.5% (± 12.5%). At a mean follow-up of 62.8 months (51 to 81) there was no change in the mean range of movement, and no statistically significant difference in the Insall-Salvati index or tibial slope (p = 0.11 and p = 0.15, respectively). The mean hip-knee-ankle angle changed from 190.6 (183° to 197°) to 176.0° (171° to 181°), with a mean final position of the mechanical axis of 58.5% (35.1% to 71.2%). The desired alignment was attained in 31 of 37 (84%) knees. There were 21 excellent, 13 good, two fair and one poor result according to the Oxford knee score with no correlation between age and final score. This score was at its best at one year with a statistically significant deterioration at two years (p = 0.001) followed by a small but not statistically significant deterioration until the final follow-up (p = 0.17). All the knees with Ahlback grade 1 osteoarthritis had excellent or good results. Complications included pin tract infections involving 16.4% of all pins used, delayed union in two, knee stiffness in four, fracture of the lateral cortex in one and ring sequestrum in one. In conclusion, hemicallostasis provides precision in attaining the desired alignment without interfering with tibial slope or patellar height, and is relatively free of serious complications.     

The anteroposterior axis of the tibia in total knee arthroplasty for chinese knees

The goal of this study was to corroborate the use of Akagi's anteroposterior (AP) axis as a rotation reference axis for the tibial component. Transverse computed tomography (CT) scans of the knees of 20 healthy Chinese men (mean age, 34.2±7.9 years; range, 20-43 years) and 20 healthy Chinese women (mean age, 36.7±5.8 years; range, 25-48 years) were obtained. Measurements taken from CT slices at the level of the tibial plateau revealed a mean percentage of the patellar tendon intersected by the AP axis from its medial border of 8%±8.1% (range, 8.1%-23.5%). When the defined AP axis was superimposed on CT slices at the level of the patellar tendon attachment, mean percentage of the width of the patellar tendon intersected by the AP axis from its medial border was 0.2%±10%. Mean angle measurement of angle α was 0.1°±2.7° (range, -5.1° to 5.8°). Mean angle measurement of angle β, or the angle created by the AP axis and the medial third of the patellar tendon from the middle of the posterior cruciate ligament, was 10.3°±3.6° (range, 2.4°-18.8°). The study confirms that Akagi's AP line is reproducible and reliable. The AP line can be used as a rotation reference axis for the tibial component during preoperative CT scanning of the knee.     

股骨远端旋转对线参考轴线与胫骨机械轴关系的研究

目的 研究股骨远端旋转对线参考轴线与胫骨机械轴的关系,确定最为可靠参考轴线,并探讨其优越性.方法 对30例下肢尸体标本分别在膝关节伸直位、屈膝90°进行数码照相,照片经计算机处理后,分别测量股骨机械轴、临床髁上轴的垂线、外髁髁上轴的垂线、Whiteside线与胫骨机械轴的夹角,并将其相比较进行统计学分析.结果 临床髁上轴的垂线、外髁髁上轴的垂线、Whiteside线、股骨机械轴相对于胫骨机械轴分别为内翻0.6°、内翻3.9°、外翻0.2°、内翻3.0°.临床髁上轴、外髁髁上轴、Whiteside线在伸膝时与屈膝时比较分别为外翻2.3°、内翻0.9°、外翻3.1°.股骨机械轴与胫骨机械轴的夹角大于临床髁上轴垂线、Whiteside线与胫骨机械轴的夹角,其差异具有统计学意义(P0.05).结论 外髁髁上轴是较临床髁上轴、Whiteside线更为可靠的股骨假体旋转对线参考标志,术中参考外髁髁上轴行股骨后髁切骨时可获得相对良好的胫股关节、髌股关节运动轨迹.