Mini-subvastus approach for total knee arthroplasty

The mini-subvastus surgical technique avoids both quadriceps arthrotomy and patella eversion. Since March 2003, this quad-sparing minimally invasive surgical (MIS) technique has been applied to more than 98% of our primary total knee arthroplasty (TKA) patients. This study compares our first 150 MIS TKA patients to our previous 150 traditional TKA patients. Quadriceps recovery was rapid in the MIS group with 83% able to do a straight leg raise the day after surgery. Hospital length of stay was decreased in the MIS group, 3.4 days, vs the traditional group, 4.1 days (P = .00013). Fewer MIS patients required skilled nursing or rehabilitation center admission. Increased knee flexion was seen for the MIS patients throughout the first 2 years of follow-up. Mean knee flexion at 1 year was 127 degrees for the MIS patients vs 114 degrees in the traditional TKA patients (P < .0001). Comparison between the MIS and traditional techniques demonstrated no increase in the number or severity of complications and no difference in operating room time.     

重度膝关节外翻畸形的全膝关节置换术

 目的 探讨重度膝关节外翻畸形全膝关节置换术的手术方法及临床效果。方法 对2007年1月至2012年12月采用全膝关节置换治疗的重度膝关节外翻畸形患者22例（23膝）进行回顾性分析。男7例,女15例;年龄41~78岁,平均65岁。股胫角（股骨和胫骨解剖轴线的夹角）22°~50°,平均为34.6°。骨关节炎17例,类风湿关节炎5例。髌骨完全脱位3例3膝,内侧不稳定1例1膝,屈曲挛缩畸形3例4膝。21例22膝采用后稳定型假体,1例1膝采用限制型假体。髌旁内侧入路、常规截骨及单纯外侧软组织松解,术中行髌骨置换5例。以膝关节活动度、X线股胫角及美国特种外科医院（Hospital for Special Surgery,HSS）膝关节评分评价术后疗效。结果 全部病例随访时间1~5年,平均2.5年。膝关节活动度由术前平均43.7°±5.8°（0°~80°）提高至末次随访时110.6°±7.5°（80°~130°）,HSS膝关节评分由术前平均（19.6±4.7）分（6~34分）提高至末次随访时（89.7±3.6）分（84~96分）,手术前后的差异有统计学意义。外翻畸形基本得到矫正,末次随访时股胫角平均为8.6°±0.8°（0°~12°）,较术前34.6°±2.4°（22°~50°）明显改善,手术前后的差异有统计学意义。术后2例2膝有膝关节内侧不稳症状,给予膝关节支具保护;1例1膝术前严重髌骨脱位患者术后存在半脱位,未予特殊处理;2例2膝术后出现腓总神经麻痹,未予特殊处理。随访期间未发生感染、松动及深静脉血栓形成等并发症。结论 对重度膝关节外翻畸形患者可采用常规截骨、单纯外侧软组织松解及后稳定型假体植入,能较好地矫正外翻畸形,近期疗效满意。     

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。     

Navigation-assisted less invasive total knee arthroplasty compared with conventional total knee arthroplasty: a randomized prospective trial

The purpose of this study was to evaluate the hypothesis that a less invasive (LIS) surgical technique using a navigation system would promote rapid recovery and improve alignment compared with conventional technique in total knee arthroplasty (TKA). This study compared 49 navigation-assisted LIS TKAs with 53 conventionally performed TKAs using a medial parapatellar arthrotomy with patellar eversion. Navigation-assisted LIS TKA used a shorter skin incision, a midvastus approach without patella eversion, and a navigation system. Navigation-assisted LIS TKA had better pain scores, shorter times to achieve 90 degrees flexion and straight leg raise, and a smaller extension lag during the very early postoperative period. However, there were no differences between the groups 2 weeks postoperatively. There were no differences in mean prosthetic alignment between the 2 groups, but the navigation-assisted LIS group had fewer "outliers" than the conventionally performed TKA group.     

Subvastus approach for total knee arthroplasty: a prospective, randomized, and observer-blinded trial

A prospective, randomized, and blinded trial was conducted with 89 consecutive primary knee arthroplasties comparing standard medial parapatellar arthrotomy with the subvastus approach. All patients received the same prosthesis (Insall-Burstein II) inserted by one surgeon using an identical technique with the only difference being the approach. The parapatellar approach (group I) was used in 43 knees, and in the remaining 46 knees the subvastus approach (group II) was used. Assessment revealed significantly earlier return of straight-leg raise (3.2 days vs 5.8 days, P <.001), lower consumption of opiates in the first week (78 mg vs 102 mg, P <.001), less blood loss (527 mL vs 748 mL, P <.001), and greater knee flexion at 1 week (78 degrees vs 55 degrees, P <.001) in group II (subvastus approach). The subvastus approach offers early advantages over the standard parapatellar arthrotomy. It preserves the integrity of the vastus medialis and peripatellar plexus of vessels. We advise its wider use in primary total knee arthroplasty.     

Surgical accuracy with the mini-subvastus total knee arthroplasty a computer tomography scan analysis of postoperative implant alignment

A total of 50 total knee arthroplasty (TKA) patients, 25 traditional and 25 minimally invasive surgical (MIS), underwent computed tomography scans to determine if a loss of accuracy in implant alignment occurred when a surgeon switched from a traditional medial parapatellar arthrotomy to a mini-subvastus surgical technique. Surgical accuracy was determined by comparing the computed tomography measured implant alignment with the surgical alignment goals. There was no loss in accuracy in the implantation of the tibial component with the mini-subvastus technique. The mean variance for the tibial coronal alignment was 1.03 degrees for the traditional TKA and 1.00 degrees for the MIS TKA (P = .183). Similarly, there was no difference in the mean variance for the posterior tibial slope (P = .054). Femoral coronal alignment was less accurate with the MIS procedure, mean variance of 1.04 degrees and 1.71 degrees for the traditional and MIS TKA, respectively (P = .045). Instrumentation and surgical technique concerns that led to this loss in accuracy were determined.     

膝关节外翻畸形的人工全膝关节置换术

目的探讨膝关节外翻畸形患者行人工全膝关节置换术(TKA)的手术方法和临床效果。方法对1996年1月至2004年8月74例87个膝关节外翻畸形TKA手术进行回顾分析。患者男11例,女63例,平均年龄63岁(26~80岁);股胫角(股骨和胫骨解剖轴线的夹角)平均为21·59°(12°~40°);应用后稳定型假体,采用髌旁内侧入路、常规截骨加单纯外侧软组织松解方法。随访检查膝关节活动度、X线外翻角度及KSS评分以评价手术效果。结果术后评价随访时间33·8个月(5个月~9年),根据膝关节活动度数及KSS评分评估关节功能情况。膝关节平均活动度为112·4°(80°~130°),KSS评分平均为81·7分(71~93分),比术前提高了59分;功能评分平均为86·3分,比术前提高了59·8分。所有膝关节在行TKA后外翻畸形基本得到矫正,随访时外翻度数(股胫角)平均为8·7°(0°~11°),较术前有明显改善。随访时1例患者有膝关节轻度不稳症状,1例术前严重髌脱位患者术后髌骨存在半脱位,其余正常。结论对于膝关节外翻畸形患者,采用髌旁内侧入路、常规截骨加单纯外侧软组织松解以及安装后稳定型假体的方法,可取得比较满意的临床效果。     

Arthroscopic treatment of patellar clunk.

Excellent results have been reported with posterior stabilized total knee arthroplasty. A common complication relating to patellofemoral articulation is patellar clunk syndrome. Patellar clunk syndrome occurs when a fibrous nodule develops just proximal to the patellar button. At approximately 30 degrees to 45 degrees from full extension, the nodule catches the anterior flange of the femoral prosthesis, resulting in the clunk and a painful range of motion. The present study examines the use of arthroscopic debridement for this disorder. Thirty consecutive patients (32 knees) with the diagnosis of patellar clunk syndrome were evaluated at 1 year after arthroscopic debridement. All patients were evaluated clinically and radiographically according to the Knee Society score. In addition, patients were questioned specifically regarding anterior knee pain and patellofemoral symptoms. Radiographs were evaluated further regarding patella and component position. Patients were diagnosed with patellar clunk at an average of 12 months after their latest knee arthroplasty, with a range of 3 to 47 months. All patients complained of anterior knee pain and the clunk. All patients had a hypertrophic nodule at the junction of the proximal pole of the patella and quadriceps tendon and underwent arthroscopic debridement through a superolateral portal. All patients were free of patellar clunk postoperatively; one patient reported persistent anterior knee pain. Knee Society scores increased from an average of 64 points preoperative to 93 points postoperative. Radiographs showed patella alta in eight knees, patella baja in two. Four femoral components were in 5 degrees flexion. The present study represents the largest collection of data regarding patellar clunk syndrome. The data appear to support arthroscopic debridement as a successful treatment of patellar clunk syndrome.     

Patellar clunk syndrome after posterior stabilized total knee arthroplasty

Two hundred thirty-six posterior stabilized total knee arthroplasties (TKAs) were performed consecutively. Twenty-seven patellar clunk syndromes were identified in 25 patients. Insall-Salvati ratio, position of joint line, postoperative patellar height, and anterior-posterior position of tibial tray were measured. It was found that postoperative low-lying patella (P<.001) and anterior placement of tibial tray (P=.011) was associated with patellar clunk syndrome. Thirteen patients had bilateral TKAs of the same prosthesis (5 bilateral AMK knees and 8 bilateral Insall Burstein knees) but unilateral patellar clunk syndrome. The nonclunk sides were used as control for comparison with the clunk sides. The congruency and tilting of the patellar button in the skyline view were documented. It was observed that the congruency of the patellar button was less satisfactory in the clunk side (P=.019).     

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。     

固定平台后稳定型假体全膝关节置换术后的运动学研究

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

The impact of minimally invasive surgical techniques on early range of motion after primary total knee arthroplasty

A single surgeon performed 200 consecutive primary total knee arthroplasties using identical implants. One hundred of these were done using a traditional medial parapatellar arthrotomy. The other knees were done using a medial parapatellar approach combined with minimally invasive surgical techniques. Patients in the minimal incision group had shorter incision length, shorter length of stay, and less pain (P < .01). Moreover, those patients in the minimal incision group had less flexion contracture (P < .05) and better flexion (P < .05) in the first 12 weeks. Manipulation was necessary in 14% of the traditional group compared with 2% in the minimal incision group (P < .001). There was no significant difference in range of motion or functional outcome at 1 year after surgery. There was no significant difference in component position or complication rates.     

人工全膝关节置换术在外翻膝的临床应用

[目的]探讨人工全膝关节置换术在外翻膝中的手术技术和临床疗效.[方法]2004年3月～2008年9月,对14例16个外翻膝行膝前正中、髌旁内侧入路,常规截骨、外侧软组织松解,后方稳定型假体或后交叉韧带保留型假体的人工全膝关节置换术进行回顾性研究.患者男3例,女11例,平均年龄60.5岁(45～77岁).经过随访比较手术前后膝关节屈伸活动度、KSS评分、膝关节X线情况来评估手术临床效果.[结果]术后平均随访42个月(24～54个月),膝关节屈伸活动度由术前平均82°(伸直0°～屈曲120°)提高到术后120°(伸直0°～屈曲150°);KSS评分:临床评分由术前平均43分(10～65分)提高到术后平均83.9分(70～100分),功能评分由术前平均52.9分(30～70分)提高到术后平均89.3分(75～100分);胫股角由术前平均16.5°(8°～30°)改善纠术后平均7°(5°～10°),膝外翻畸形得到良好的矫正.随访中无深静脉血栓、膝关节感染、髌骨半脱位或脱位并发症发生.[结论]膝前正中、髌旁内侧入路,常规截骨、外侧软组织松解,后方稳定型假体或后交叉韧带保留型假体的TKA治疗外翻膝临床疗效满意.     

全膝关节置换术治疗膝骨关节炎合并固定性髌骨脱位

目的评估全膝关节置换术治疗膝骨关节炎合并固定性髌骨脱位患者的临床疗效。方法对6例膝骨关节炎合并固定性髌骨脱位的患者(8膝)行全膝关节置换术。采用标准内侧髌旁入路,并行“+”形松解外侧支持带,常规髌骨置换,使用非限制性后稳定假体。比较手术前后的HSS评分和疼痛VAS评分,测量股骨胫骨角(FTA)和伸膝迟滞。结果患者均获得随访,时间1~8年。HSS评分从术前25~63分提高到术后1年75~94分。VAS评分从术前5~8分下降至术后1年0~3分。FTA从术前161°~173°改善至术后1年173°~175°。术前有10°~25°的伸膝迟滞,术后基本消失。结论采用标准内侧髌旁入路结合外侧结构的松解作全膝关节置换术治疗膝骨关节炎合并固定性髌骨脱位可获得良好的临床疗效。     

止血带对全膝关节置换术中股骨远端旋转定位时髌骨轨迹的影响

目的 探讨止血带对全膝关节置换术中以外科髁上轴线为股骨远端旋转定位线的髌骨轨迹的影响.方法 2002年12月至2008年8月,首选以外科髁上轴线为股骨远端旋转定位标志的初次全膝关节置换349例(526膝),男124例(155膝),女225例(371膝);年龄33～84岁,平均68岁.膝内翻387膝,膝外翻94膝.均使用同一种保留后十字韧带的活动平台假体,由同一位手术医生操作.采用前内侧髌旁入路,以外科髁上轴线为股骨远端旋转定位线,以no thumb test检测髌骨轨迹.对髌骨轨迹不良者,缝合髌骨内上缘支持带并松开止血带.对再次检查髌骨轨迹不良者行外侧支持带松解术.术后3个月患者能够极度屈曲膝关节时摄X线片检查髌骨轨迹.结果 术中no thumb test阳性138膝,其中半脱位12膝(膝外翻),髌骨倾斜126膝(膝外翻74膝).缝合髌骨内上缘支持带并松开止血带后,no thumb test阳性40膝,其中半脱位8膝(膝外翻),髌骨倾斜32膝(膝外翻29膝).髌骨外侧支持带松解率7.6%(40/526),膝外翻松解率39.4%(37/94).结论 在全膝关节置换术中,高压止血带对髌骨轨迹有干扰作用.术中缝合髌骨内上缘支持带并松开止血带,可降低外侧支持带松解率.     

Evaluation of patellar retinacular tension during total knee arthroplasty: Special emphasis on lateral retinacular release

Tension of a suture placed to the patella to close the medial capsule during 35 primary total knee arthroplasties was measured. The increase in tension with flexion after arthrotomy was significantly smaller in 10 knees with a subvastus incision (subvastus group) than in 25 knees with a standard medial parapatellar incision (standard group). With the prosthesis in place, the patella showed maltracking with the no-thumb technique in 1 knee (10%) of the subvastus group and in 9 knees (36%) of the standard group. A lateral retinacular release was performed in 5 of these 10 knees but not in the remaining 5 knees because the increase in tension was a minimum. There was no case of patellar maltracking at an average follow-up period of 2.1 years after surgery, suggesting that a lateral release is not always needed if retinacular tension shows no significant increase, even cases where the patella dislocates with the no-thumb technique.     

Synovial entrapment: a complication of posterior stabilized total knee arthroplasty

BACKGROUND: We observed a complication of posterior stabilized total knee arthroplasty involving hypertrophy of tissue proximal to the patella associated with pain during active knee extension from 90 degrees of flexion. The purpose of this paper was to describe synovial entrapment and to determine if design features of the prosthesis predispose patients to the complication. METHODS: Between April 1990 and June 1999, we performed 459 consecutive posterior stabilized primary total knee arthroplasties using three prosthetic designs with different femoral intercondylar geometries. We identified twenty-six patients (twenty-seven knees) in whom arthroscopic débridement of the knee or open arthrotomy with débridement of the knee had been subsequently performed because of a diagnosis of synovial entrapment. We reviewed the records of these patients to identify the knee components that had been used and the symptoms and conditions that necessitated additional treatment. RESULTS: Symptoms (grating, crepitation, and pain with active knee extension from 90 degrees) necessitating subsequent débridement occurred in 13.5% (nineteen) of 141 knees treated with the Anatomic Modular Knee-Congruency implant, 3.8% (eight) of 212 treated with the Anatomic Modular Knee-Posterior Stabilized implant, and none of the 106 treated with the Press Fit Condylar Sigma-Posterior Stabilized implant. All patients had difficulty rising from a chair and climbing stairs; however, none had symptoms when standing or walking. No patient had a patellar clunk. The symptoms occurred at a mean of seven months after the arthroplasty in the patients with an Anatomic Modular Knee-Congruency implant and at a mean of twenty months after the arthroplasty in those with an Anatomic Modular Knee-Posterior Stabilized implant. Débridement of the frond-like hypertrophic synovial tissue at the distal aspect of the quadriceps tendon alleviated symptoms in all patients. No nodules were identified during the arthroscopy. CONCLUSIONS: Synovial entrapment is characterized by hypertrophic synovial tissue at the superior pole of the patella. Use of a posterior stabilized femoral component with a proximally positioned or wide femoral box is more likely to result in this complication.     

改良髌旁外侧入路用于外翻膝人工全膝关节置换术

目的探索外翻膝人工全膝关节置换入路与软组织平衡的新技术。方法设计并应用于临床兼有松解髌外侧支持带功能的改良髌旁外侧入路,通过平行分离髌骨外侧支持带深浅两层,并向外翻转脂肪垫暴露膝关节,术中松解髌骨外侧支持带、髂胫束或膝关节后外侧关节囊、膝外侧副韧带等紧张结构,假体安装后错位缝合外侧支持带深层与浅层,既维持了松解的外侧支持带的适当张力和髌股关节正常活动轨迹,又确保了术后深筋膜的闭合。术后2周内行CPM锻炼,2周后扶拐行走。结果11例患者下肢力线从术前平均外翻10.2°矫正至平均内翻1.5°,膝关节冠状面畸形矫正率达85.3%。术后伤口愈合良好,术后2个月伸屈活动度平均达105°,11例患者均可自如地平地行走,其中9例可上下楼梯。膝关节稳定性好。结论改良髌旁外侧入路能较方便地显露膝关节外侧稳定结构,有利于对外侧挛缩结构的精确松解,并保持良好的髌股关节活动轨迹,是严重外翻膝行全膝关节置换的良好入路。     

Applicability of the mini-subvastus total knee arthroplasty technique: an analysis of 725 cases with mean 2-year follow-up

Recent total knee arthroplasty (TKA) studies suggest a more rapid functional recovery with minimally invasive surgical (MIS) techniques. These studies often fail to disclose the percentage of primary TKA that underwent the MIS technique, raising the concern that positive clinical outcomes are a result of patient selection. This study evaluates the applicability of the mini-subvastus technique in one surgeon's consecutive primary TKA patients. The applicability was determined utilizing a computer record review to determine the percentage of primary TKA patients in which the surgeon utilized a MIS surgical technique. The mini-subvastus approach was applied to 99% of 732 consecutive primary TKA. There was no patient selection based on age or weight. Traditional TKA, utilizing a medial parapatellar arthrotomy, was more likely to be performed on patients with a diagnosis of traumatic arthritis and in knees that required stems or augments. Preoperative tibiofemoral angle and mean knee deformity were not predictors of which procedure would be utilized. Despite employing this new surgical approach in nearly all primary TKAs, there was no increase in the complication rate. This high applicability rate with the mini-subvastus technique obviates concerns that the positive clinical outcomes in these patients are a result of patient selection.     

Kinematics of medial osteoarthritic knees before and after posterior cruciate ligament retaining total knee arthroplasty

Total knee arthroplasty (TKA) is a widely accepted surgical procedure for the treatment of patients with end‐stage osteoarthritis (OA). However, the function of the knee is not always fully recovered after TKA. We used a dual fluoroscopic imaging system to evaluate the in vivo kinematics of the knee with medial compartment OA before and after a posterior cruciate ligament‐retaining TKA (PCR‐TKA) during weight‐bearing knee flexion, and compared the results to those of normal knees. The OA knees displayed similar internal/external tibial rotation to normal knees. However, the OA knees had less overall posterior femoral translation relative to the tibia between 0° and 105° flexion and more varus knee rotation between 0° and 45° flexion, than in the normal knees. Additionally, in the OA knees the femur was located more medially than in the normal knees, particularly between 30° and 60° flexion. After PCR‐TKA, the knee kinematics were not restored to normal. The overall internal tibial rotation and posterior femoral translation between 0° and 105° knee flexion were dramatically reduced. Additionally, PCR‐TKA introduced an abnormal anterior femoral translation during early knee flexion, and the femur was located lateral to the tibia throughout weight‐bearing flexion. The data help understand the biomechanical functions of the knee with medial compartment OA before and after contemporary PCR‐TKA. They may also be useful for improvement of future prostheses designs and surgical techniques in treatment of knees with end‐stage OA. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:40–46, 2011