关节置换前后髌骨高度对膝关节功能的影响

目的:研究全膝关节置换术前、术后Insall-Salvati指数和改良Insall-Salvati指数与术后膝关节活动度的关系。方法:采用HSS评分系统对患者全膝关节置换术后半年至一年的关节功能、活动度、肌力、屈曲畸形、稳定性等进行评价。测量81例(106膝)患者术前、术后X线片Insall-salvati指数及改良Insall-salvati指数。结果:术后HSS评分为(89±10)分,术前Insall-salvati指数及改良Insall-salvati指数分别为(1.00±0.13)、(1.61±0.21),术后Insall-salvati指数及改良Insall-salvati指数分别为(0.94±0.19)、(1.67±0.34)。关节置换术后Insall-salvati指数较置换前显著降低(P0.05),改良Insall-salvati指数显著提高(P0.05)。术后低位髌骨组(Insall-salvati指数0.8)HSS评分、活动度和屈曲畸形分值均较正常髌骨组(0.8Insall-salvati指数1.5)显著降低(P0.05)(P0.05)。高位髌骨组(Insall-salvati指数1.5)和正常髌骨组各项评分均无显著差异(P0.05)。术前改良Insall-salvati指数小于1.8的患者术后膝关节HSS评分、功能、活动度、肌力、屈曲畸形、稳定性显著高于大于1.8的患者(P0.05)。结论:术前改良Insall-salvati指数和术后Insall-salvati指数可作为评价术后膝关节功能的参考指标。术前、术后的膝关节高度均会影响术后关节功能,全膝关节置换术中精确截骨对术后关节功能十分重要。     

腓骨近端截骨术与胫骨高位截骨术治疗内侧间室性膝关节骨关节炎的比较研究

目的:对比内侧间室性膝关节骨关节炎(KOA)患者应用腓骨近端截骨术与胫骨高位截骨术治疗的疗效。方法:选取2016年11月到2017年12月在我院接受治疗的内侧间室性KOA患者32例,采用随机数字表法将所有患者分为腓骨近端截骨组与胫骨高位截骨组各16例,比较两组患者的手术时间、住院时间、术中出血量和住院费用,比较两组患者术前、术后3个月、术后6个月的美国特种外科医院膝关节评分(HSS)、美国膝关节协会评分(KSS)、视觉模拟疼痛评分(VAS)和股胫角(FTA),比较两组患者术后出现的并发症的发生率。结果:腓骨近端截骨组患者的手术时间、住院时间短于胫骨高位截骨组,术中出血量和住院费用均显著少于胫骨高位截骨组(P0.05);术后3个月、术后6个月两组患者的HSS评分、KSS评分均明显高于术前,VAS评分、FTA均明显低于术前(P0.05);术前、术后3个月、术后6个月两组患者的HSS评分、KSS评分、VAS评分、FTA比较均无统计学差异(P0.05);两组患者的并发症发生率比较无统计学差异(P0.05)。结论:腓骨近端截骨术和胫骨高位截骨术均可有效治疗内侧间室性KOA,改善患者的膝关节功能和疼痛感,纠正内翻畸形,但腓骨近端截骨术手术时间和住院时间更短,术中出血量和住院费用更少。     

旋转平台与后稳定固定平台假体在人工膝关节置换术后的临床疗效

目的:探讨旋转平台与后稳定固定平台假体在人工膝关节置换术(TKA)后的临床治疗效果。方法:选择2008年8月到2014年8月在我院接收人工膝关节置换术的218例患者,随机分为对照组和实验组,分别采用后稳定固定平台假体和旋转平台假体行TKA。观察并记录两组患者治疗前和治疗后6个月世界膝关节学会(KSS)评分、美国膝关节学会(HSS)评分和膝关节的屈曲度(ROM),以及治疗后6个月并发症的发生情况。结果:治疗后,两组患者KSS评分、HSS评分及ROM评分均明显高于治疗前,差异有统计学意义(P0.05);两组患者KSS评分、HSS评分及ROM评分相比,差异无统计学意义(P0.05)。实验组患者并发症发生率(9.17%)和对照组患者并发症发生率(10.09%)相比,无统计学意义(P0.05)。结论:旋转平台与后稳定固定平台假体在TKA中均能有效改善膝关节的功能,两者疗效相近,均值得在临床推广应用。     

全膝关节置换术与单髁置换术治疗老年膝关节骨关节炎的疗效比较

目的:探讨全膝关节置换术与单髁置换术对老年膝骨关节炎患者的临床疗效及术后恢复情况。方法:收集我院就诊的94例膝骨关节炎患者,随机分为UKA组和TKA组,每组各47例。UKA组采用单髁置换术治疗,TKA组采用全膝关节置换术治疗。观察并比较两组患者治疗前后膝关节功能评分(KSS)、疼痛视觉模拟评分(VAS)以及手术时间、术中出血量及术后并发症的发生情况等。结果:与治疗前相比,治疗后两组患者KSS评分均升高,VAS评分均下降,差异具有统计学意义(P0.05);与TKA组相比,UKA组VAS评分水平较低,KSS评分水平较高,差异具有统计学意义(P0.05);与TKA组相比,UKA组手术时间短,术中出血量少,差异具有统计学意义(P0.05);两组患者治疗后的并发症发生率差异无统计学意义(P0.05)。结论:在掌握适应证的前提下,与全膝关节置换术相比,单髁置换术创伤小、出血量少,关节功能恢复较好。     

经股内侧肌入路降低全膝关节置换术术后不良反应及促进膝关节功能康复

为评估髌骨旁内侧入路和经股内侧肌入路两种手术技术在全膝关节置换术(total knee arthroplasty,TKA)中的早期功能结果,本研究选取50例2013年3月至2017年3月期间在我院行全膝关节置换数的患者作为研究对象,随机分为两组。一组患者通过髌骨旁内侧入路进行TKA手术,另外一组患者通过经股内侧肌入路方法进行TKA手术。所有患者均只进行一次手术,两组均使用相同类型的植入物。使用视觉模拟评分法(visual analogue scale, VAS)记录疼痛评分,并在术后3周和6周时获得随访数据,包括股四头肌强度和本体感受。结果表明,TKA术后,经股内侧肌入路组患者在休息和运动时表现出明显较低的疼痛(VAS:平均2.13±1.87与2.84±1.76)和(VAS:平均3.11±2.16与3.21±2.02)。此外,经股内侧肌入路组患者在3周((41.2±17.8) Nm vs (27.3±14.1) Nm)和6周((47.4±19.5) Nm vs (35.6±16.2) Nm)显示出优异的等长股四头肌强度。另外,经股内侧肌入路组患者术后本体感觉良好,而两组患者的运动范围相似。研究初步表明,在早期康复期间,经股内侧肌入路方法比髌骨旁内侧入路更有优势。没有观察到与此方法相关的不良影响。因此,经股内侧肌入路应被认为是TKA中有价值的替代方法。     

全膝关节置换术治疗晚期类风湿性关节炎的早期临床随访研究

目的:探讨全膝关节置换术(TKA)治疗晚期类风湿性膝关节炎(RA)的早期临床疗效和安全性。方法:回顾性分析2006年~2011年接受TKA治疗的69例(102膝)晚期膝关节RA患者的临床资料,术后及随访时分析患者的影像学资料,末次随访时进行膝关节HSS评分,采用英国矫形外科协会标准评定患者满意度,SF-36健康量表评定患者的生活质量。结果:54例(81膝)患者术后获得2~7年(平均4.3年)随访;6例(7膝)死亡,6例(10膝)失访,3例(4膝)翻修,获得随访患者中1例(1膝)发生下肢深静脉血栓,经介入放置滤网治疗康复后出院,1例(1膝)感染。末次随访时,膝关节活动度(ROM)从术前平均(71.03°±29.51°)提高至(92.26°±10.29°),膝关节HSS评分从术前平均(47.30±10.06)分提高至(75.93±9.17)分;疼痛发生率和疼痛评分均较术前显著降低;冠状面和矢状面畸形率均较术前显著降低;身体健康(PCS)平均(47.98±6.96)分,心理健康(MCS)平均(41.45±5.67)分,均较术前显著增加,差异均有统计学意义(P0.05)。患者的治疗满意率为96.30%,膝关节假体X线片采用膝关节学会的X线评价与计分系统评价未见假体松动。结论:TKA治疗晚期膝关节RA患者2~7年的临床及影像学效果良好,未发现骨溶解、假体松动及严重衬垫磨损等并发症。     

全膝关节置换术对膝关节骨关节炎患者关节功能的影响

目的:探讨全膝关节置换术(TKA)对膝关节骨关节炎患者术后关节功能的影响。方法:回顾性分析2013年8月-2015年8月我院收治的76例膝关节骨关节炎患者的临床资料,所有患者均采用全膝关节置换术治疗。观察并比较患者手术前后膝关节HSS评分、膝关节疼痛目测类比评分(VAS)、膝关节屈曲活动度(ROM)的变化情况。结果:患者术后膝关节HSS评分、膝关节疼痛评分VAS及ROM均明显高于术前,差异具有统计学意义(P0.05);术前HSS评分、膝关节疼痛VAS评分、膝关节ROM、胫骨平台后倾角(PSA)以及股骨前髁偏距(ACO)与术后膝关节HSS评分呈正相关关系,而内翻畸形角度与术后膝关节HSS评分呈负相关关系,差异具有统计学意义(P0.05)。结论:全髋关节置换术能够改善骨关节炎患者的膝关节功能,并且术前膝关节HSS评分、膝关节疼痛VAS评分及PSA与术后患者髋关节功能恢复程度有关。     

内侧开放楔形胫骨高位截骨术治疗膝关节内翻畸形的疗效及对术后下肢力线和创伤应激的影响

摘要 目的：对比内侧开放楔形胫骨高位截骨术（OWHTO）、人工全膝关节置换术（TKA）治疗膝关节内翻畸形的疗效及对术后下肢力线和创伤应激的影响。方法：回顾性分析贵州医科大学附属医院2020年3月~2022年1月期间接收的膝关节内翻畸形患者临床资料,共计75例。根据手术方案的不同分为OWHTO组（n=40）和TKA组（n=35）。对比两组围术期指标、视觉疼痛模拟评分（VAS）评分、美国特种外科医院（HSS）膝关节评分、膝关节活动度（ROM）、应激指标和术后下肢力线改变情况。结果：OWHTO组手术时间、切口长度短于TKA组,术中出血量、住院费用少于TKA组（P<0.05）。OWHTO组术后1个月VAS评分低于TKA组,ROM、HSS膝关节评分高于对照组（P<0.05）。OWHTO组术后3 d、术后7 d血清皮质醇（COR）、促肾上腺皮质激素（ACTH）水平低于TKA组（P<0.05）。两组术后6个月股胫角（FTA）下降,髋-膝-踝角（HKA）升高（P<0.05）。两组术后6个月FTA、HKA组间对比差异不显著（P>0.05）。两组并发症发生率组间对比未见差异（P>0.05）。结论：OWHTO、TKA这两种治疗方案治疗膝关节内翻畸形,具有相当的疗效,均可有效改善下肢力线,但OWHTO的创伤小、应激程度轻。     

前交叉韧带不同断裂程度对髌骨内外侧关节面的生物力学影响

目的:探讨前交叉韧带(ACL)完全断裂和部分断裂对髌骨内外侧关节面生物力学的影响.方法:10例新鲜正常成人膝关节标本作为ACL完整组,在200N轴向载荷下,测试膝关节0°、30°、60°、90°髌骨内外侧关节面应变,测试完毕后随机将标本造模成前内侧束(AMB)切断组和后外侧束(PLB)切断组,各5例,在上述条件下测试,再将ACL中下1/3全切作为全切组进行测试.结果:膝伸直0°位各组应变无显著性差异(P＞0.05),膝屈曲30°、60°、90°各组间均有显著性差异(P＜0.05),其应变变化趋势为ACL完整组＞PLB切断组＞AMB切断组＞全切组.且髌骨内侧面应变小于髌骨外侧面应变(P＜0.05).结论:ACL完全断裂,在不同栽荷和角度下,对髌骨内外侧关节面的应变均有影响.ACL部分断裂在膝关节屈曲30°、60°、90°位可引起髌骨内外侧生物力学改变.ACL完全断裂,髌骨外侧应变高于髌骨内侧应变,其意义尚需进一步探讨.     

关节镜下清理术联合腓骨截骨术治疗膝关节骨性关节炎的疗效及对炎性因子的影响

目的:探讨采用关节镜下清理术联合腓骨截骨术治疗膝关节骨性关节炎(KOA)的疗效及对炎性因子的影响。方法:选取2015年3月～2017年12月期间右江民族医学院附属河池医院收治的KOA患者99例,根据手术方式的不同将患者分为A组(n=46,关节镜下清理术治疗)和B组(n=53,关节镜下清理术联合腓骨截骨术治疗),比较两组患者手术时间、术中出血量、住院时间,比较两组术前、术后6个月、术后1年疼痛情况、膝关节功能恢复情况、膝关节相关角,比较两组术前、术后1个月炎性因子变化,记录两组术后并发症发生情况。结果:B组手术时间长于A组(P0.05),两组术中出血量、住院时间比较无差异(P0.05)。B组术后6个月、术后1年视觉疼痛模拟(VAS)评分低于A组,美国特种外科医院(HSS)、膝关节评分及美国膝关节协会(KSS)评分则高于A组(P0.05)。两组患者术后1个月白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)均较术前降低,且B组低于A组(P0.05)。B组术后6个月、术后1年膝关节相关角[股骨干与股骨双髁连线夹角(F角)、股骨胫骨角(FT角)、胫股关节间隙角(JS角)]均低于术前以及A组同时间点(P0.05)。两组术后并发症发生率比较差异无统计学意义(P0.05)。结论:KOA患者经关节镜下清理术、腓骨截骨术联合治疗后,疗效显著,可有效改善患者疼痛及膝关节功能,降低炎性因子水平,手术方案安全且可改善患者下肢力线。     

Accuracy of mobile biplane X-ray imaging in measuring 6-degree-of-freedom patellofemoral kinematics during overground gait

The aim of this study was to evaluate the accuracy with which mobile biplane X-ray imaging can be used to measure patellofemoral kinematics of the intact knee during overground gait. A unique mobile X-ray imaging system tracked and recorded biplane fluoroscopic images of two human cadaver knees during simulated overground walking at a speed of 0.7 m/s. Six-degree-of-freedom patellofemoral kinematics were calculated using a bone volumetric model-based method and the results then compared against those derived from a gold-standard bead-based method. RMS errors for patellar anterior translation, superior translation and lateral shift were 0.19 mm, 0.34 mm and 0.37 mm, respectively. RMS errors for patellar flexion, lateral tilt and lateral rotation were 1.08°, 1.15° and 1.46°, respectively. The maximum RMS error for patellofemoral translations was approximately one-half that reported previously for tibiofemoral translations using the same mobile X-ray imaging system while the maximum RMS error for patellofemoral rotations was nearly two times larger than corresponding errors reported for tibiofemoral rotations. The lower accuracy in measuring patellofemoral rotational motion is likely explained by the symmetric nature of the patellar geometry and the smaller size of the patella compared to the tibia.     

三种不同内固定法治疗髌骨骨折82 例临床疗效的分析

目的:观察三种不同内固定法治疗髌骨骨折82例临床疗效及安全性。方法:将82例髌骨骨折患者随机分成三组,其中30人接受双克氏针钢丝环绕法治疗,髌骨周缘环形缝扎处理21例,31人应用镍钛聚髌器治疗。从手术时间、优良率、愈合时间、手术费用及并发症等指标进行评价。结果:三种内固定方法治疗髌骨骨折组的手术时间差异无统计学意义(P>0.05),镍钛聚髌器组的愈合时间、手术费用及术后并发症与双克氏针钢丝环绕法组及髌骨周缘环形缝扎处理组相比,差异具有统计学意义(P<0.05);镍钛聚髌器治疗髌骨粉碎性骨折的优良率与其它两组相比,差异具有统计学意义(P<0.05);三种方法治疗髌骨横断性骨折的优良率相互比较差异无统计学意义。结论:双克氏针钢丝环绕法、髌骨周缘环形缝扎法及镍钛聚髌器法都可以被采纳治疗髌骨横断性骨折;在治疗髌骨粉碎性骨折优先采用镍钛聚髌器法。     

Variations in the anterior patellar groove of the human femur

An analysis of the anterior patellar groove of the human femur shows considerable variation in its medial and lateral spects. The groove itself, measured by the angle it encloses, shows considerably less variation than its individual components. The suggested functional relationship between bicondylar angle and lateral elevation of the patellar groove does not obtain for this sample.     

两种内固定方法治疗髌骨骨折术后关节面对合情况的比较

目的：比较改良张力带钢丝内固定和传统张力带钢丝内固定治疗髌骨横行骨折术后关节面对合的效果。方法：2007年3月至2011年9月,分别采用胥氏张力带钢丝内固定和改良张力带钢丝内固定且随访超过1年的髌骨横行骨折的患者64例,术中分别采用胥氏张力带钢丝内固定和改良张力带钢丝内固定治疗,随访时行膝关节X线摄片检查,观察关节面对合情况,比较两种治疗方法所致关节面台阶样错位是否大于2mm的差异。结果：64例患者均获得随访,随访时间8~18个月,平均13.2个月,骨折端均愈合,两组Lysholm评分比较无统计学意义（P=0.665）;胥氏张力带钢丝内固定组和改良张力带钢丝内固定组分贝出现1例（3.1%）和7例（21.9%）关节面台阶征,两组关节面台阶征的发生率比较差异有统计学意义（P=0.036）。结论：胥氏张力带钢丝固定法使髌骨骨折术后固定作用加强,关节面对合更好,能有效预防因台阶征引起的创伤性关节炎的发生。     

镍钛聚髌器治疗髌骨骨折的电测分析

应用电阻测度应变技术,得到镍钛聚髌器这一记忆合金内固定器的应力－应变关系曲线,较为精确地测定了镍钛聚髌器动态聚合加压髌骨于解剖位的生物力学力值,结果表明：镍钛聚髌器可从9个方向产生向心聚合力,纵向为主,记忆加压力值为13．67Kg,侧向为辅,永加压力值为5．19Kg,并具有一定的耐疲劳性。本实验为临床使用及指导病人术后功能锻炼提供了科学的依据,并为研究动态记忆力学下的骨愈合机理提供了实验基础。     

张力带钢丝法治疗髌韧带断裂

目的:探讨张力带钢丝法治疗髌韧带断裂的疗效。方法:回顾分析13例髌韧带断裂的手术治疗情况。结果:1例于术后2月出现钢丝断裂,但韧带连续性和强度恢复良好。其它所有病例功能恢复均达伤前水平,无韧带再断裂。结论:采用张力带钢丝法,以及对合并髌韧带挛缩或者缺损病例,结合半腱肌肌腱重建修复髌韧带断裂效果良好。     

Murine patellar tendon biomechanical properties and regional strain patterns during natural tendon-to-bone healing after acute injury

Tendon-to-bone healing following acute injury is generally poor and often fails to restore normal tendon biomechanical properties. In recent years, the murine patellar tendon (PT) has become an important model system for studying tendon healing and repair due to its genetic tractability and accessible location within the knee. However, the mechanical properties of native murine PT, specifically the regional differences in tissue strains during loading, and the biomechanical outcomes of natural PT-to-bone healing have not been well characterized. Thus, in this study, we analyzed the global biomechanical properties and regional strain patterns of both normal and naturally healing murine PT at three time points (2, 5, and 8 weeks) following acute surgical rupture of the tibial enthesis. Normal murine PT exhibited distinct regional variations in tissue strain, with the insertion region experiencing approximately 2.5 times greater strain than the midsubstance at failure (10.80±2.52% vs. 4.11±1.40%; mean±SEM). Injured tendons showed reduced structural (ultimate load and linear stiffness) and material (ultimate stress and linear modulus) properties compared to both normal and contralateral sham-operated tendons at all healing time points. Injured tendons also displayed increased local strain in the insertion region compared to contralateral shams at both physiologic and failure load levels. 93.3% of injured tendons failed at the tibial insertion, compared to only 60% and 66.7% of normal and sham tendons, respectively. These results indicate that 8 weeks of natural tendon-to-bone healing does not restore normal biomechanical function to the murine PT following injury.     

Comparison of elastic,viscoelastic and failure tensile material properties of knee ligaments and patellar tendon

The knee ligaments and patellar tendon function in concert with each other and other joint tissues, and are adapted to their specific physiological function via geometry and material properties. However, it is not well known how the viscoelastic and quasi-static material properties compare between the ligaments. The purpose of this study was to characterize and compare these material properties between the knee ligaments and patellar tendon.Dumbbell-shaped tensile test samples were cut from bovine knee ligaments (ACL, LCL, MCL, PCL) and patellar tendon (PT) and subjected to tensile testing (n = 10 per ligament type). A sinusoidal loading test was performed at 8% strain with 0.5% strain amplitude using 0.1, 0.5 and 1 Hz frequencies. Subsequently, an ultimate tensile test was performed to investigate the stress-strain characteristics.At 0.1 Hz, the phase difference between stress and strain was higher in LCL compared with ACL, PCL and PT (p < 0.05), and at 0.5 Hz that was higher in LCL compared with all other ligaments and PT (p < 0.05). PT had the longest toe-region strain (p < 0.05 compared with PCL and MCL) and MCL had the highest linear and strain-dependent modulus, and toughness (p < 0.05 compared with ACL, LCL and PT).The results indicate that LCL is more viscous than other ligaments at low-frequency loads. MCL was the stiffest and toughest, and its modulus increased most steeply at the toe-region, possibly implying a greater amount of collagen. This study improves the knowledge about elastic, viscoelastic and failure properties of the knee ligaments and PT.     

活血化瘀汤对髌骨骨折患者膝关节功能及炎症因子的影响

目的:探讨髌骨骨折患者应用活血化瘀汤对患者膝关节功能、炎症因子的影响。方法:选择2015年3月到2017年3月西南医科大学附属中医医院接诊的髌骨骨折患者100例作为研究对象,以随机数表法分为观察组(n=53)和对照组(n=47),两组患者均采用切开复位克氏针张力带内固定,观察组加用活血化瘀汤。比较两组治疗后膝关节优良率、肿瘤坏死因子(TNF-α)、白细胞介素6(IL-6)、白细胞介素10(IL-10)、膝关节功能Lysholm评分、视觉模拟评分法(VAS)评分及不良反应发生情况。结果:治疗后,观察组患者优良率为92.45%,显著高于对照组的72.34%(P0.05);治疗前,两组患者TNF-α、IL-6及IL-10水平无显著差异(P0.05);治疗后,两组TNF-α、IL-6及IL-10水平较治疗前均显著改善(P0.05),且观察组TNF-α、IL-6均明显低于对照组,IL-10水平显著高于对照组(P0.05);治疗前,两组患者Lysholm评分、VAS评分无显著差异(P0.05);治疗后,两组Lysholm评分、VAS评分较治疗前均显著改善(P0.05),且观察组Lysholm评分均明显高于对照组,VAS评分显著低于对照组(P0.05);观察组患者不良反应总发生率为1.89%,显著低于对照组的14.89%,差异具有统计学意义(P0.05)。结论:在髌骨骨折患者中使用活血化瘀汤效果显著,可有效改善患者膝关节功能、炎症因子水平,值得推广与运用。     

Finding and defining the ideal patellar resection plane in total knee arthroplasty

Asymmetric resection of the patella during total knee arthroplasty (TKA) correlates with anterior knee pain, bony impingement and patellar maltracking. Despite this, there is no consensus regarding the desired landmarks; the cut is often done freehand; and there has been no quantitative comparison of proposed resection planes. The objectives of this study were to: determine the intra- and inter-surgeon repeatability of two radiographic resection definitions (medial–divot, MD, and medial–lateral extents, MLE); calculate two additional definitions from the radiographic patellar circumferences (parallel to the anterior surface, ANT, and perpendicular to the anteroposterior tangent points, PERP); compare the clinical resection line to the previous four definitions before and after introducing the MD method clinically; and identify distinguishing features of patellae with better vs. worse resection angles. We hypothesized that the MD method would improve repeatability both radiographically and clinically, that the different radiographic definitions would produce comparable angles, and that we could identify distinguishing features. For the radiographic study, three surgeons drew lines on 40 preoperative X-rays plus 9 interspersed repetitions of 3 of these X-rays. For the clinical study, we compared the patellar resection angle for 20 patients immediately before and after implementing the new method. Given that the clinical goal is to have equal distances from the resection surface to the anterior surface, we compared all results to the ANT definition as the theoretically ideal definition. Confirming the first hypothesis, intra-surgeon repeatability (10 repetitions of 3 X-rays) and inter-surgeon repeatability (3 surgeons×40 X-rays) were both significantly better using the new MD method compared to the MLE method (p<0.001). Contrary to the second hypothesis, clinical use of the MD method did not improve resection symmetry. Contrary to the third hypothesis, the PERP definition was significantly different from the other three definitions. In agreement with the fourth hypothesis, female patellae and more deformed patella had significantly greater asymmetry (p<0.001). Given the inherent variability shown in drawing the ‘patellar horizon’, we encourage researchers to draw the line several times and average the results when comparing tilt or the resection angle to this horizon. Based on the distinguishing characteristics of asymmetrically resurfaced patellae in our series, we recommend that clinicians be particularly careful when resecting laterally deformed patellae and the patellae of female patients.