Aggravation of Ankle Varus Incongruency Following Total Knee Replacement Correcting ≥10° of Genu Varum Deformity: A Radiographic Assessment

BackgroundThis study aimed to investigate the change in ankle varus incongruencies following total knee replacement (TKR) in patients with preoperative genu varum deformity of ≥10°.MethodsThe study cohort was composed of patients who underwent TKR in a single institution for knee osteoarthritis with preoperative genu varum deformity of ≥10° and concomitant varus ankle incongruencies. Eight radiographic measurements were evaluated preoperatively and postoperatively: mechanical tibiofemoral angle, mechanical lateral distal femoral angle, medial proximal tibial angle, lateral distal tibial angle, tibial plafond inclination, talar inclination, tibiotalar tilt angle (TTTA), and tibia-mechanical axis angle. Of these, TTTA represented the quantitative degree of ankle joint incongruency.ResultsA total of 110 patients (male = 2; female = 108) were included in the analysis. The mean patient age was 68.9 (standard deviation [SD] 7.2) years at the time of TKR. All radiographic measurements showed significant changes postoperatively, representing the appropriate correction of genu varum deformity and restoration of the mechanical axis. Nineteen patients (17.3%) showed postoperative decrease in TTTA, 2 (1.8%) remained the same, and 89 (80.9%) showed increase. Overall, mean preoperative and postoperative TTTA were 3.3° (SD 2.2°) and 4.7° (SD 2.9°), respectively (P < .001), representing the aggravation of varus ankle incongruencies.ConclusionVarus ankle incongruencies showed aggravation following TKR despite correction of genu varum deformity and restoration of the mechanical axis. This could be an important cause of postoperative increase or development of ankle pain following TKR. Therefore, patients with preoperative varus ankle incongruencies need to be warned of possible aggravation of ankle symptoms and be evaluated before TKR.Level of EvidencePrognostic level III.     

Lower limb alignment in healthy Japanese adults

BackgroundKnowledge regarding the normal alignment of the lower limb is important when considering alignment for total knee arthroplasty. However, few studies have explored the lower limb alignment of healthy Japanese subjects.MethodsBetween July and October 2020, we performed whole leg standing radiography of 120 legs of 60 healthy adult Japanese volunteers aged <50 years in the closed-leg stance. The measurement parameters were hip knee ankle angle (positive for varus), percentage of constitutional varus (hip knee ankle angle ≥ 3°), mechanical axis deviation ratio, mechanical lateral distal femoral angle, medial proximal tibial angle, joint line convergence angle (positive for lateral opening), and tibial joint line angle (positive for medial inclination).ResultsThe mean measured values for all volunteers, men and women, were as follows: hip knee ankle angle (°), 2.3, 2.6, and 2.0; mechanical axis deviation ratio, 35.8, 35.6, and 36.9; mechanical lateral distal femoral angle (°), 86.7, 87.0, and 86.7; medial proximal tibial angle (°), 85.6, 85.0, and 86.2; joint line convergence angle (°), 0.6, 0.3, and 0.8; and tibial joint line angle (°), ?1.0, ?0.7, ?1.4, respectively. The percentage of constitutional varus was 35.8% overall, 35.8% in men and 35.3% in women. Only the medial proximal tibial angle was smaller in men than that in women (p = 0.003).ConclusionsThe mechanical lateral distal femoral and medial proximal tibial angles were smaller, hip knee ankle angle was larger, and percentage of constitutional varus was higher in Japanese subjects than those reported for subjects in other countries. Our findings improve the understanding of Japanese-specific alignments when considering alignment for lower limb surgery, especially, total knee arthroplasty.     

Effect of Total Knee Arthroplasty on Coronal Alignment of the Ankle Joint

BackgroundThe effect of total knee arthroplasty (TKA) on the ankle joint is not entirely clear. The purpose of this study is to assess postoperative changes in the coronal alignment of the ankle joint in patients undergoing TKA for various degrees of knee deformity.MethodsThis retrospective study included 107 patients who had undergone TKA for primary osteoarthritis. In all cases, preoperative coronal alignment deformity of the knee was corrected in an attempt to restore the native mechanical axis of the knee. Patients were stratified into 3 groups according to the degree of knee coronal alignment correction achieved intraoperatively: group 1 (<10° varus/valgus correction, n = 60), group 2 (≥10° varus correction, n = 30), and group 3 (≥10° valgus correction, n = 17). Knee/ankle alignment angles were measured on full-length, standing anteroposterior imaging preoperatively and postoperatively and included the following: hip-knee-ankle angle, tibial plafond inclination (TPI), talar inclination (TI), and tibiotalar tilt angle.ResultsSignificant changes in ankle alignment, specifically with regard to TPI (9.5° ± 6.9°, P < .01) and TI (8.8° ± 8.8°, P = .03) were noted in the ≥10° valgus correction group compared to the other 2 groups. Regardless of the degree of knee deformity correction, TKA did not lead to significant changes in the tibiotalar tilt angle.ConclusionA correction of ≥10° in a genu valgum deformity can affect ankle joint alignment, leading to alterations in TPI and TI. These findings need to be taken into consideration in assessing candidates for TKA as a possible cause of postoperative ankle pain.     

Effect of total ankle replacement on the 3-dimensional subtalar joint alignment in varus ankle osteoarthritis

BackgroundVarus ankle osteoarthritis (OA) is typically associated with peritalar instability, which may result in altered subtalar joint position. This study aimed to determine the extent to which total ankle replacement (TAR) in varus ankle OA can restore the subtalar alignment.MethodsFourteen patients (15 ankles, mean age 61 ± 6 years) who underwent TAR for varus ankle OA were analyzed using semi-automated measurements based on weight-bearing computed tomography. Twenty healthy individuals served as a control group.ResultsAll angles improved between preoperative and a minimum of 1 year (mean 2.1 years) postoperative and were statistically significant in 6 out of 8 angles (P < 0.05).ConclusionsOur findings indicate that talus repositioning after TAR restores the subtalar joint alignment which may improve hindfoot biomechanics. Future studies are required to implement these findings for TAR in presence of hindfoot deformity.Level of evidenceIV.     

Morphology of the transepicondylar axis and its application in primary and revision total knee arthroplasty

A morphologic anatomic study was done of the lower extremity to investigate various relationships of the transepicondylar axis (TEA). Thirteen cadaver specimens were dissected and mounted to a metal frame with a pin passing through the TEA. The center of the knee was determined as the depth of the anterior intercondylar groove. The ratio of the upper leg to lower leg measured from femoral head center and ankle center to TEA was 1.02. The mean distance of the TEA to the joint line was 3.08 cm medial and 2.53 cm lateral. The mean femoral angle comparing the TEA to mechanical axis was 0.61° varus. The mean tibial angle comparing the TEA to the mechanical axis was 0.4° varus in extension and 0.43° in flexion, with no significant difference in the lower extremity angle with flexion (P < .01). The TEA is an important landmark that, from this study, is virtually perpendicular to the mechanical axis of the lower extremity and parallels the knee flexion axis. Femoral component rotation and joint line positioning in total knee arthroplasty can be determined using the TEA.     

The Position of the Tibial Component Affecting the Postoperative Mechanical Axis in Total Knee Arthroplasty

The purpose is to identify whether the position of the tibial component in relation to the anatomical axis affects the postoperative mechanical axis in total knee arthroplasty for Korean patients. Preoperatively, 30 patients with varus deformity lesser than 10° were classified as group A, and 30 patients greater than 10° were classified as group B. Postoperatively, the distance between the midline of the tibial stem and anatomical axis (medial offset) was measured. The medial offsets were 2.5 ± 1.9 mm in group A and 3.9 ± 2.7 mm in group B (P = .021). The postoperative mechanical axes were varus 1.3 ± 1.2° in group A and varus 2.5 ± 2.0° in group B (P = .004). We think that the medial position of tibial component in relation to the anatomical axis affects the measurement of postoperative mechanical axis in total knee arthroplasty.     

Assessment of knee alignment after bicompartmental knee arthroplasty

A key factor in successful knee arthroplasty is restoration of correct knee alignment. Although traditional total knee arthroplasty effectively restores alignment, it is unclear whether similar results can be consistently obtained with more conservative procedures. The purpose of this study was to assess alignment after implantation of the Journey Deuce Bi-Compartmental Knee System (Smith & Nephew, Inc, Memphis, Tenn). Mechanical axis was assessed in 137 cases. Preoperatively, 77 (56%) of 137 patients had a mechanical axis passing far medial to the center of the knee, consistent with varus deformity. Postoperatively, 130 (95%) of 137 patients had a mechanical axis passing through the center of the knee. These results suggest that the Journey Deuce Bi-Compartmental Knee System supports correction of varus deformity, previously thought to require total knee arthroplasty or osteotomy.     

Intraoperative Tibial Anteroposterior Axis Could Not Be Replicated After Tibial Osteotomy in Total Knee Arthroplasty

BackgroundWe evaluated the effect of the anteroposterior (AP) axis of the proximal tibia defined at the cutting surface using an image-free navigation system in total knee arthroplasty.MethodsThis prospective study included 68 patients (79 knees) who underwent total knee arthroplasty. The tibial AP axis was registered in the navigation system with reference to Akagi’s line, connecting the middle of the posterior cruciate ligament to the medial border of the patellar tendon attachment at the tibial joint surface. After proximal tibial osteotomy, the AP axis was replicated as the AP(O) axis. We measured the difference between the AP axis defined at the joint surface and the AP(O) axis defined at the osteotomy surface.ResultsThe AP(O) axis at the osteotomy surface internally rotated 2.0° to the AP axis at the joint surface, and the AP(O) axis outlier (difference to AP axis: >3°) occurred in 54% (43 knees). In the >3° malrotation group, internal malrotation occurred in 37% (30 knees) and external malrotation occurred in 17% (13 knees). In the outlier analysis, the left knees were significantly found in the internal outlier group.ConclusionThe tibial AP axis, connecting the middle of the posterior cruciate ligament to the medial border of the patellar tendon attachment defined at the tibial joint surface, could not be replicated at the tibial osteotomy surface. If the tibial components were set depending only on the AP axis defined at the osteotomy surface, the tibial components could internally rotate and have more outliers, especially in the left knees.     

Osteotomy Around the Knee: The Surgical Treatment of Osteoarthritis

Osteoarthritis causes joint pain and functional disorder, of which knee osteoarthritis is the most common. Nowadays, clinically effective treatments mainly include conservative treatment, arthroplasty, and osteotomy. However, conservative treatment only offers symptomatic relief and arthroplasty is limited to the patients with a moderate to severe degree of osteoarthritis. For relatively young patients who require greater knee preservation, a surgical treatment with low operation trauma and revision rate is needed. Osteotomy around the knee, based on the notion of “knee preservation,” has been chosen as an alternative surgical treatment. Cutting and realigning the bones corrects the mechanical line of lower limb force bearing. As such, osteotomy around the knee retains normal anatomical structure and obtains good functional recovery of the knee joint. The techniques of osteotomy around the knee includes anti‐varus deformity and anti‐valgus deformity osteotomy, aiming to reallocate the force bearing in the compartment of the knee joint. By choosing the surgical section of the lower limbs, the osteotomy around the knee can achieve the correction of mechanical axis, such as the high tibial osteotomy (HTO), proximal fibular osteotomy (PFO), and distal femur osteotomy (DFO). Numerous modified techniques have been developed to meet the demands of patients based on traditional methods. These modified osteotomy have their own advantages and indications. This paper aims to guide clinical treatment by reviewing different types of osteotomies, and their effects, that have been studied and applied widely in clinical practices.     

Radiographic effects observed in the coronal view after medial malleolar osteotomy at total ankle arthroplasty in rheumatoid arthritis cases

BackgroundWhen soft tissue balance is not acceptable at total ankle arthroplasty (TAA) for rheumatoid varus deformity, medial malleolar osteotomy has been performed. At the same time, the shape of the ankle joint changes after soft tissue balancing with such an osteotomy, however there is few information for the radiographic findings after the osteotomy. Thus, radiographic changes in the coronal view of such cases were investigated.MethodsJSSF-RA foot and ankle scale and SAFE-Q scores were determined along with pre/postoperative radiographic parameters of the ankle joint in 70 ankles (65 patients) with rheumatoid arthritis followed for a mean of 7.9 years (range, 2–16 years) after TAA. Seven ankles were excluded because those underwent lateral or lateral/medial malleolar osteotomy. Twenty-seven ankles underwent medial malleolar osteotomy, and compared with 36 ankles without osteotomy.ResultsAll ankles achieved bone union after medial malleolar osteotomy, and the tibial medial malleolus (TMM) angle was significantly decreased [30.3°–19.1°] following significant valgus correction [TC angle: −2.7° to 0.5°]. The gap due to medial soft tissue tightness was significantly improved by medial malleolar osteotomy [4.95° to 0.7°]. Lateral malleolar fractures sometimes occurred (19%: 5/27 ankles) at valgus correction, but they healed completely without any internal fixation.ConclusionMedial malleolar osteotomy was useful in rheumatoid varus ankle for not only controlling the soft tissue balance, but also providing a stabilized shape of the ankle joint. Lateral malleolar fractures were caused by valgus correction following medial malleolar osteotomy in some cases, but all fractures were completely healed without any internal fixation.     

合并膝内翻骨性关节炎全膝关节置换的处理

目的探讨膝骨性关节炎合并膝内翻畸形者行膝关节置换时膝内翻的矫正方法。方法172例（190膝）合并内翻畸形骨性关节炎患者进行全膝关节表面置换术。术前测量膝内翻角、关节面夹角、胫骨角、胫骨内翻角及胫骨平台后倾角,其内翻角为8°～21°,参考关节面夹角、胫骨角及胫骨内翻角确定膝内翻的类型,术中根据膝内翻的类型及构成因素进行相应的胫骨截骨及适度的软组织松解。结果出现切口感染2例（2膝）,1例为急性感染,1例为迟发性感染,2例均经清创、假体取出并膝关节融合术后痊愈。术后内翻矫正157膝,仍有膝内翻33膝,内翻角3°～9°（4.8°±0.9°）。165例（182膝）获得随访,时间8～90（40±3.5）个月。末次随访时除2例感染外,余膝关节活动度为：伸直0°168膝,伸直受限＆lt;10°11膝,伸直受限11°～15°3膝;屈曲90°～130°。临床及X线检查未见明显松动迹象。HSS膝关节评分由术前12～57（30±5.5）分提高到76～89（79.2±4.3）分。结论术前明确膝内翻的类型及构成因素,术中采取针对性操作进行适度的软组织松解及正确的截骨,是全膝关节置换膝内翻获得矫正的有效方法。     

Slot双下肢全长负重位X线摄影在全膝关节置换术前的应用

目的观察Slot双下肢全长负重位X线检查技术在全膝关节置换术前检查中的应用价值。方法对36例拟接受全膝关节置换术的患者术前行双下肢全长负重位X线检查。采用Slot技术,通过一次连续数秒曝光获得包含双髋关节至踝关节的双下肢全长负重位X线影像。结果 36例患者均一次性完成全膝关节置换术前双下肢全长负重位X线检查,其中膝关节内翻畸形34例,外翻畸形2例。所摄X线片中,患者双髋关节、股骨、膝关节、胫腓骨及踝关节均显示良好,可为术前计划提供可靠依据。结论采用Slot双下肢全长负重位X线检查技术对拟接受全膝关节置换术患者进行术前检查,能够清晰显示双下肢全长,对术前计划与评估具有重要临床价值。     

Normal axial alignment of the lower extremity and load-bearing distribution at the knee

Based on a series of 120 normal subjects of different gender and age, the geometry of the knee joint was analyzed using a full-length weight-bearing roentgenogram of the lower extremity. A special computer program based on the theory of a rigid body spring model was applied to calculate the important anatomic and biomechanical factors of the knee joint. The tibiofemoral mechanical angle was 1.2 degrees varus. Hence, it is difficult to rationalize the 3 degree varus placement of the tibial component in total knee arthroplasty suggested by some authors. The distal femoral anatomic valgus (measured from the lower one-half of the femur) was 4.2 degrees in reference to its mechanical axis. This angle became 4.9 degrees when the full-length femoral anatomic axis was used. When simulating a one-legged weight-bearing stance by shifting the upper-body gravity closer to the knee joint, 75% of the knee joint load passed through the medial tibial plateau. The knee joint-line obliquity was more varus in male subjects. The female subjects had a higher peak joint pressure and a greater patello-tibial Q angle. Age had little effect on the factors relating to axial alignment of the lower extremity and load transmission through the knee joint.     

胫骨高位双平面截骨术治疗膝内侧间室骨关节炎

目的探讨胫骨高位双平面截骨术治疗膝内侧间室骨关节炎的近期疗效。方法采用胫骨高位双平面截骨术治疗37例膝内侧间室骨关节炎患者。测量手术前后膝关节站立负重位X线片胫股解剖角、髋—膝—踝角,记录手术前后膝关节损伤和骨关节炎KOOS评分、KSS评分和疼痛VAS评分。结果患者均顺利完成手术。术后未出现感染、骨筋膜室综合征、腓总神经损伤、下肢深静脉血栓等并发症,截骨处愈合良好,患者膝内翻畸形情况均得到矫正。37例均获得随访,时间6~30(18.6±7.0)个月。胫股解剖角、髋—膝—踝角、KOOS评分、KSS评分、VAS评分术后3个月较术前明显改善,差异均有统计学意义(P<0.001)。结论胫骨高位双平面截骨术治疗膝内侧间室骨关节炎能够纠正下肢异常力线,缓解或者消除膝关节疼痛症状,短期疗效满意。     

Changes in the subtalar joint alignment after supramalleolar osteotomy for varus ankle arthritis

BackgroundThe subtalar joint may compensate for tibio-talar deformity, but what would happen to the joint after the deformity was corrected is not well known. Supramalleolar osteotomy (SMOT) is an effective procedure for the treatment of varus deformity of ankle arthritis. The objective of this study was to investigate the subtalar joint alignment pre and postoperatively following SMOT, and the factors which influenced the alignment of the subtalar joint.MethodsThirty-one patients with varus ankle arthritis (Takakura stage 2, 3a and 3b) who were treated using SMOT were retrospectively reviewed. The subtalar and ankle joint alignment was measured on weightbearing radiograph and weightbearing computerized tomography (WBCT).ResultsThe foot and ankle offset (FAO), tibial articular surface angle (TAS), tibio-talar surface angle (TTS), and subtalar vertical angle (SVA) were significantly corrected (P＜0.05). The subtalar inclination angle (SIA) decreased in 19 patients and increased in the other 12 cases after the SMOT (P＜0.001). The shift of subtalar joint (ΔSIA) showed an inverse correlation with the preoperative FAO (P＜0.001, r = −0.621).ConclusionsThe shift of subtalar joint after SMOT could maintain the neutral position of the hindfoot and showed a negative correlation with the preoperative FAO. The ΔSIA was greater in the severer preoperative hindfoot deformity.Level of evidenceLevel IV, case series.     

开放楔形胫骨高位截骨术不同程度矫正内翻畸形的比较

目的研究开放楔形胫骨高位截骨术(OWHTO)后过度矫正内翻畸形的并发症发生情况和临床疗效，并通过放射学指标比较髋关节、髌股关节与踝关节的代偿性变化。 方法回顾性分析2016年1月至2020年5月期间在青岛大学附属医院行OWHTO治疗的63例患者的资料，纳入标准为诊断明确、有症状的膝骨关节炎伴内翻畸形，排除双侧手术、术前有膝关节感染及既往外伤史的患者。根据术后测量承重线比率(WBLR)，将所有患者分为正常矫正组52例(50%2＝4.395，P＝0.036)。在OWHTO后，比较两组患者末次HKA和MPTA，差异有统计学意义(t＝6.586、3.709，均为P<0.001)，比较末次随访两组患者HAA，差异有统计学意义(t＝-2.309，P＝0.026)。其余影像学指标比较，差异均无统计学意义(均为P>0.05)。两组患者HSS评分、WOMAC评分末次随访比较，两组患者差异无统计学意义。 结论过度矫正内翻畸形(术后WBLR≥67%)不影响OWHTO后早期的临床效果，但增加了术后并发症的发生率，从影像学上，引起髋关节代偿性的内收加剧。     

胫骨高位嵌插截骨与传统高位截骨治疗高龄屈曲型膝内侧间隙骨关节炎的对比研究

目的:报告胫骨高位嵌插截骨治疗高龄屈曲型膝内侧间隙骨关节炎的方法疗效,并与传统高位胫骨截骨的疗效进行比较。方法:2003年7月至2007年7月对年龄60～82岁,病史3～20年,屈曲度7°～19°的膝内侧间隙骨关节炎的30例患者随机分成2组,分别进行胫骨高位嵌插截骨和传统高位截骨手术治疗。术后观察骨折愈合时间、膝关节内翻畸形和屈曲畸形恢复、膝关节功能恢复等情况。要求患者术后第4、6、8、9、10、12、14、16周及5、7、9、12个月复查,记录骨折愈合时间及内翻、屈曲角度纠正情况。术后12个月时根据Lysholm膝关节评分标准进行评分,并对2组的疗效进行比较。结果:胫骨高位嵌插截骨组平均骨折愈合时间(9.26±2.23)周,传统高位截骨组平均(11.53±3.15)周,2组相比差异有统计学意义(P0.05)。膝关节功能恢复方面,术后1年,根据Lysholm评分标准进行评分,胫骨高位嵌插截骨平均(88.5±4.4)分,优14例,良1例;传统高位截骨组平均(78.1±5.7)分,优8例,良5例,可2例。胫骨高位嵌插截骨组术后膝关节伸直位角度0°～-1.1°,术后平均矫正(13±3.3)°;传统高位截骨组术后膝关节伸直位角度与术前相同,为(14°±3.3)°。两组术后站立位X线测量,FTA平均170.2°(l69.1°～172.3°),平均矫正12.3°～12.5°。结论:胫骨高位嵌插截骨手术治疗膝关节内侧间隙骨关节炎缩短了骨折愈合时间,同时矫正了膝关节内翻畸形和屈曲畸形,更好地恢复了膝关节的功能,此手术方式明显优于传统的高位截骨术。     

胫骨高位截骨治疗膝骨性关节炎中长期疗效分析

目的 :分析胫骨高位截骨治疗膝骨性关节炎的中长期疗效。方法 :自2001年1月至2005年12月,采用胫骨高位截骨术治疗45例63膝关节内侧间室骨性关节炎患者,男10例(15膝),女35例(48膝);年龄45~64岁,平均(54.76±5.54)岁。术前常规行膝关节负重正侧位X线检查,准确测量股胫角大小,根据术前股胫角决定胫骨外侧截骨量,手术均在硬膜外麻醉下常规行胫骨高位截骨术,大部分行腓骨中段截骨,部分病例行上胫腓关节松解。术后第2天即行功能锻炼,2周开始无负重下床活动,术后8~10周开始负重。术后第2天、8~10周、半年、1年及以后每年1次拍片复查,对全部病例术前、术后3~5年、术后10~14年采用视觉模拟评分(VAS)、美国特种外科医院膝关节评分(HSS)和美国膝关节协会评分(KSS)评价膝关节疼痛、畸形、功能和运动范围。结果 :43例(61膝)进行了10年及以上的随访,全部患者手术切口Ⅰ期愈合,术后8~10周截骨处均达骨性愈合。术后10~14年HSS评分平均76.24±5.27,优27膝,良25膝,可7膝,差2膝。术前与术后3~5年、术前与术后10~14年VAS、HSS、KSS比较有差异,术后3~5年与术后10~14年各项评分无明显差异。结论:胫骨高位截骨治疗膝骨性关节炎(内侧间室关节炎)只要手术指征掌握适当,术后积极锻炼,其中长期疗效满意。     

The effect of ankle rotation on cutting of the tibia in total knee arthroplasty

BACKGROUND: Extramedullary alignment guides are commonly used to prepare the tibia during total knee arthroplasty. One disadvantage is that the guide is easily affected by the position of the ankle joint. The tibia may have a rotational mismatch between its proximal and distal ends. We hypothesized that a rotational mismatch might cause incorrect positioning of an extramedullary alignment guide and evaluated such a mismatch on the predicted postoperative coronal alignment of the tibia. METHODS: Fifty-three osteoarthritic knees with varus deformity in fifty-one patients were evaluated with use of computerized tomography scans before total knee arthroplasty. We defined one anteroposterior axis of the ankle joint and five different anteroposterior axes of the proximal aspect of the tibia using three-dimensional bone models from the computerized tomography data. We measured the rotational angle between the anteroposterior axis of the ankle joint and the proximal part of the tibia. The distal end of the extramedullary guide was placed in front of the center of the ankle joint (on the line of the extended anteroposterior axis of the ankle joint), and the proximal end was placed on the line of the extended anteroposterior axis of the proximal part of the tibia. We established spatial coordinates to evaluate the effect of the rotational angle on the predicted postoperative coronal alignment of the tibia and calculated the presumed tibial coronal alignment. RESULTS: The rotational angle was positive (3.6 degrees to 19.7 degrees) for all of the anteroposterior axes of the proximal aspect of the tibia, indicating that the ankle joint was externally rotated relative to the proximal part of the tibia. The predicted tibial coronal alignment was varus (0.5 degrees to 5.1 degrees) for all of the anteroposterior axes of the proximal part of the tibia. CONCLUSIONS: When an extramedullary alignment guide is used to prepare the tibia in total knee arthroplasty, varus alignment of the tibial component can occur because of a rotational mismatch between the proximal part of the tibia and the ankle joint.