全膝关节置换术中髌骨置换与髌骨成形对膝关节功能的影响

 目的 探讨髌骨置换与髌骨成形对全膝关节置换术后膝关节功能的影响。方法 对2010年8月至11月拟行全膝关节置换术的48例(69膝)膝关节骨关节炎患者进行随机分组,髌骨置换组24例(35膝)、髌骨成形组24例(34膝)。两组患者年龄、体重、身高、体重指数、美国膝关节协会(Knee Society Score,KSS)膝评分及功能评分、髌骨评分的差异均无统计学意义。比较两组术后6周、3个月、6个月、12个月、24个月的KSS膝评分及功能评分、髌骨评分、术后膝前痛发生率及影像学表现。结果 髌骨置换组20例(30膝)与髌骨成形组20例(29膝)获得随访。术后各时点两组KSS膝评分的差异无统计学意义;6个月以后髌骨置换组KSS功能评分高于髌骨成形组,12个月以后髌骨置换组髌骨评分高于髌骨成形组,差异有统计学意义。术后各时点髌骨置换组膝前痛发生率与髌骨成形组的差异有统计学意义。术后24个月髌骨置换组与髌骨成形组术后胫股角(174.25°±0.97°与173.63°±0.48°)、髌韧带比值(1.01±0.09与1.09±0.07)、髌骨倾斜角(4.58°±0.18°与4.41°±0.19°)、髌骨适合角(2.69°±4.15°与2.56°±3.72°)、髌骨移位距离[(1.53±1.34) mm与(1.68±1.23) mm]的差异均无统计学意义。结论 全膝关节置换术中行髌骨置换可以改善膝关节和髌骨功能,降低术后膝前痛的发生率。     

髌骨软骨退变分级对保留髌骨型全膝关节置换术疗效的影响

 目的 探讨髌骨软骨退变Outerbridge分级对保留髌骨型全膝关节置换术疗效的影响。方法 对2007年2月至2010年1月因膝关节退变性骨关节炎行保留髌骨型全膝关节置换术的151例进行回顾性分析。男65例,女86例;年龄56～82岁,平均(65±5.0)岁。随访时间2～5年,平均3.5年。术中对髌骨软骨退变分级的评定采用Outerbridge标准,统计末次随访时不同髌骨软骨退变分级患者的满意度及膝前痛发生情况,视觉模拟评分(visual analogue scale,VAS)>3分判定为有膝前痛;比较不同髌骨软骨退变分级患者的美国膝关节学会评分(Knee Society Scale,KSS)及髌骨评分。结果 OuterbridgeⅠ级18例、Ⅱ级36例、Ⅲ级62例、Ⅳ级35例。膝前痛发生率4.0%(6/151),其中轻度疼痛4例、中度2例。无翻修病例,总体满意率96.7%(146/151)。不同髌骨软骨退变分级患者的满意度(H=5.54,P=0.14)、膝前痛发生率(H=0.56, P=0.91)、KSS膝评分(F=1.95, P=0.12)、功能评分(F=2.11,P=0.10)及髌骨评分(F=1.35, P=0.26)的差异均无统计学意义。结论 不同髌骨软骨退变分级患者行保留髌骨型全膝关节置换术后疗效无差异,对退变性骨关节炎患者行全膝关节置换术时无须置换髌骨。     

髌骨钻孔减压改善全膝关节置换术后膝前疼痛

目的探讨通过髌骨钻孔减压术改善全膝关节置换术(TKA)后膝前痛的临床疗效。方法将符合标准的113例行TKA的骨关节炎患者按数字法随机分为两组:54例为减压组,TKA术中联合髌骨钻孔减压术;59例为非减压组,仅施行TKA不联合髌骨钻孔减压术。术后观察两组患者切口愈合情况、相关并发症、KSS评分及膝前痛发生率。结果两组患者切口均一期愈合,无严重并发症发生,113例均获满12个月的完整随访。KSS评分:减压组术后明显高于非减压组;术后膝前痛的发生率明显低于非减压组,差异均有统计学意义(P0.05)。结论 TKA术中联合髌骨减压术可以在一定程度上改善膝关节KSS评分及降低术后膝前疼痛的发生率。     

人工全膝关节置换术中髌骨置换的临床研究

目的通过与非髌骨置换比较,探讨髌骨置换对人工全膝关节置换术疗效的影响。方法将2010年9月-11月符合选择标准的63例(63膝)拟行人工全膝关节置换术的骨关节炎患者随机分为两组,其中32例关节置换术中行髌骨置换(置换组),31例不作置换(非置换组)。两组患者性别、年龄、病程、骨关节炎分级、美国膝关节协会评分系统(KSS)标准临床评分及关节功能评分、髌骨评分、髌骨倾斜角、胫股角及髌韧带比值等一般资料比较,差异均无统计学意义(P>0.05),具有可比性。术后6周及3、6、12个月对疗效进行临床及影像学评定。结果两组患者术后切口均Ⅰ期愈合,置换组6例、非置换组8例出现下肢深静脉血栓形成。患者均获12个月随访。置换组术后3、6、12个月时膝前疼痛发生率均低于非置换组(P<0.05)。两组术后各时间点KSS临床评分比较,差异无统计学意义(P>0.05);除术后6周及3个月,其余各时间点置换组关节功能评分明显高于非置换组(P<0.05)。两组髌骨评分除术后12个月外,其余各时间点组间比较差异均无统计学意义(P>0.05)。X线片复查示,两组均无髌骨骨折、髌骨脱位、髌骨不稳、假体松动及断裂发生;术后12个月两组股胫角、髌韧带比值、髌骨倾斜角比较,差异均无统计学意义(P>0.05)。结论人工全膝关节置换术中行髌骨置换可以一定程度改善膝关节功能评分、髌骨评分及降低术后膝前疼痛的发生率。     

单半径与多半径假体全膝关节置换术治疗重度膝关节骨性关节炎的疗效比较

目的比较单半径假体与多半径假体全膝关节置换术治疗重度膝关节骨性关节炎的临床疗效。方法回顾性分析自2012-08—2016-05诊治的60例严重膝关节骨关节炎,30例采用单半径假体行全膝关节置换术治疗(单半径组),30例采用多半径假体行全膝关节置换术治疗(多半径组)。比较2组术后1、3、6个月膝关节屈曲90°时膝前痛VAS评分,以及术后2年KSS膝评分、KSS功能评分、膝关节活动度。结果 60例均获得随访,随访时间3~5(4.2±1.4)年,单半径组术后1、3、6个月膝关节屈曲90°时膝前痛VAS评分,术后2年的KSS膝评分、KSS功能评分、膝关节活动度优于多半径组,差异有统计学意义(P <0.05)。结论相比于多半径假体,单半径假体全膝关节置换术治疗重度膝关节骨性关节炎具有术后疼痛更轻、膝关节活动度更大、功能恢复更好等优势。     

保留髌骨型全膝关节置换术的中期疗效

目的评价膝关节退变性骨关节炎行保留髌骨型全膝关节置换术(total knee arthroplasty,TKA)后膝前痛发生率、临床功能及髌骨软骨退变等级对临床疗效的影响。方法回顾分析2006年2月至2009年2月采用保留髌骨型TKA治疗151例(151膝)膝关节退变性骨关节炎患者的临床资料。其中男59例,女92例;平均年龄72.3岁(56~82岁)。髌骨软骨退变等级采用Outerbridge分级标准、术后膝前痛采用VAS评分、临床功能采用美国膝关节学会评分(the knee society scale,KSS)和髌骨评分(Patellar scores,PS)。结果平均随访时间(6.4±1.8)年。所有患者切口达Ⅰ期愈合。髌骨软骨退变等级:Ⅰ级18例,Ⅱ级36例,Ⅲ级62例,Ⅳ级35例。末次随访时,6例(4.0%)患者有膝前疼痛,其中轻度疼痛4例,中度2例,无重度疼痛。患者平均KSS评分由术前(82.6±9.3)分提高到术后(169.8±13.2)分;患者平均PS由术前(10.5±3.3)分提高到术后(27.8±4.5)分。不同髌骨软骨退变不影响术后膝前痛发生率(χ2=0.42,P=0.94)、KSS评分(膝评分:F=1.83,P=20.14;功能评分:F=0.56,P=20.64)和PS评分(F=0.78,P=20.51)。结论膝关节退变性骨关节炎行保留髌骨型TKA术可取得满意的临床疗效,髌骨软骨退变等级不影响临床疗效。     

全膝关节置换术中髌骨面修整与髌骨置换的比较研究

目的比较全膝关节置换术髌骨面修整和髌骨置换的临床结果。方法2002年1月至12月对60例（60膝）行初次全膝关节置换术的骨性关节炎患者进行前瞻性、随机化研究。所有患者接受相同的后交叉韧带替代型全膝关节假体（PFC）,患者随机行髌骨面修整（髌骨面修整组）或髌骨置换（髌骨置换组）。58例患者平均随访54个月（40～60个月）,对其进行临床评价,包括膝关节协会评分（KSS）、膝关节活动度（ROM）、患者满意度和X线检查。结果两组患者KSS总评分（P=0．12）、KSS疼痛评分（P=0．90）、患者满意度（P=0．22）无明显差异;两组术后膝前痛的发生率均为10％亦无明显差异。两组ROM（P=0．028）和KSS功能评分（P=0．0098）差异有统计学意义。结论全膝关节置换术不论是髌骨面修整还是髌骨置换均能明显减轻疼痛和改善功能。术后膝前痛可能与假体设计和手术技术有关,并非与是否置换髌骨有关。     

髌骨置换与否对全膝关节置换术后疗效的影响

目的 探讨膝骨关节炎患者行全膝关节表面置换时髌骨置换与否对术后疗效及并发症发生的影响.方法 对2007年1月至2011年12月之间行人工全膝关节置换术的170例(237膝)骨关节炎患者,按髌骨置换(126膝)和未置换(111膝)分为2组.对术前和末次随访时两组的HSS评分、膝前痛评分、膝关节活动度、最大屈曲度数、屈曲畸形及手术时情况和患者满意度等进行对比分析.结果使用SPSS 17.0统计软件包进行统计学分析.结果 在170例(237膝)OA患者中161例(21 3膝)获得随访,平均随访时间(40.94±8.02)个月,置换组HSS评分由术前的(40.19±8.14)分增加到末次随访时的(87.45±6.00)分(P＜0.05),膝前痛评分由(4.13±1.08)分升高到(19.47±4.04)分(P＜0.05);未置换组HSS评分由(40.00±6.74)分上升到(88.93±4.92)分(P＜0.05),膝前痛评分由(3.58±2.26)分变化到(13.61±3.89)分(P＜0.05);患者满意度置换组为80.91％,未置换组为61.17％(P＜0.05).在HSS评分、膝关节活动度、最大屈曲度数、屈曲畸形等方面两组差异无统计学意义.而在膝前痛评分、患者满意度、手术时间、术中失血量等方面差异有统计学意义.结论 当膝关节骨关节炎患者进行全膝关节置换术时,若术前存在膝关节疼痛严重、患者期望较高、不适合长时间手术,应行髌骨置换.     

固定平台型与活动平台型膝关节假体人工全膝关节置换术后膝前痛的比较研究

目的比较采用固定平台型与活动平台型膝关节假体行人工全膝关节置换术(total knee arthroplasty,TKA)后发生膝前痛的差异。方法 2008年1月-10月收治72例骨性关节炎患者,其中37例采用固定平台型膝关节假体置换(固定平台组),35例采用活动平台型膝关节假体置换(活动平台组)。固定平台组:男8例,女29例;年龄57～76岁,平均69.6岁。左膝20例,右膝17例。体重55～92 kg,平均66.7 kg。体重指数(body mass index,BMI)为17.6～37.3,平均26.2。病程3～22年。根据膝关节学会评分系统(KSS)标准评定膝评分(29.4±15.3)分,功能评分(33.4±16.8)分。髌骨评分(7.2±2.5)分,疼痛评分(2.5±2.2)分。Insall-Salvat(iI-S)指数为1.6±0.3。活动平台组:男9例,女26例;年龄58～73岁,平均68.2岁。左膝30例,右膝5例。体重50～86 kg,平均67.9 kg。BMI为18.4～34.4,平均25.6。病程6～18年。KSS膝评分(30.9±14.7)分,功能评分(31.4±14.4)分。髌骨评分(6.8±3.1)分,疼痛评分(2.0±2.3)分。I-S指数为1.6±0.2。两组患者一般资料比较,差异均无统计学意义(P>0.05),具有可比性。结果两组患者术后切口均Ⅰ期愈合,无下肢深静脉血栓形成及肺栓塞发生。患者术后均获随访,随访时间为12～16个月。术后活动平台组发生膝关节感染1例,膝关节脱位1例,膝关节弹响3例;固定平台组发生膝关节弹响1例。两组末次随访时KSS膝评分及功能评分、疼痛评分及髌骨评分比较,差异均无统计学意义(P>0.05);两组以上指标分别与术前比较,差异均有统计学意义(P<0.05)。末次随访时两组适合角、外侧髌骨角、髌骨倾斜角、髌骨外移距离、髌骨移位距离及I-S指数比较,差异均无统计学意义(P>0.05)。术后1～5个月固定平台组7例(18.9%)、活动平台组5例(14.3%)出现膝前痛。两组膝前痛发生率比较,差异无统计学意义(χ2=0.227,P=0.634)。术后出现膝前痛患者KSS膝评分、功能评分、髌骨评分及I-S指数与未出现膝前痛患者比较,差异均有统计学意义(P<0.05);其余各指标差异均无统计学意义(P>0.05)。结论采用固定平台型与活动平台型膝关节假体行TKA术后膝前痛发生率及术后近期疗效无明显差异。     

Genesis Ⅱ与PFC两种假体全膝关节置换术后膝前痛的比较研究

目的 探讨全膝关节置换术后膝前痛与髌骨置换及假体设计的关系,GenesisⅡ与PFC两种股骨假体与髌骨之间的友好性.方法 回顾性分析由同一组高年资医生施行初次全膝关节置换术的145例(145膝)骨关节炎患者的临床资料.均采用后十字韧带替代型全膝关节假体,髌骨置换74例,其中32例使用GenesisⅡ假体、42例使用PFC假体;髌骨未置换71例,其中38例使用GenesisⅡ假体、33例使用PFC假体.术后评估美国特种外科医院(Hospital for Special Surgery,HSS)膝关节评分、髌骨评分、髌骨功能评分、膝关节活动度、膝前痛评分、满意度和X线片上髌骨倾斜和半脱位情况.结果 随访144例,随访时间21～43个月,平均33个月.术后膝前痛发生率:髌骨置换组与未置换组的差异无统计学意义,组内使用GenesisⅡ假体与PFC假体的差异有统计学意义.使用PFC假体者4例再次手术.功能评分:髌骨置换组及髌骨未置换组中使用GenesisⅡ假体与PFC假体术后HSS评分、活动度、满意度的差异均无统计学意义,而术后髌骨评分及髌骨功能评分的差异有统计学意义.结论 术后膝前痛的发生率与是否置换髌骨无关,而与假体设计有关;GenesisⅡ假体与髌骨的关系更加友好.     

Patellar resurfacing in total knee arthroplasty. A prospective,randomized study

BACKGROUND: Anterior knee pain following total knee arthroplasty is a common complaint and typically is attributed to the patellofemoral joint. The purpose of the present study was to compare the outcome of resurfacing and nonresurfacing of the patella, particularly with regard to anterior knee pain, and to clarify the indications for patellar resurfacing at the time of total knee arthroplasty. METHODS: We performed a prospective, randomized study of 514 consecutive primary press-fit condylar total knee replacements. The patients were randomized to either resurfacing or retention of the patella. They were also randomized to either a cruciate-substituting or a cruciate-retaining prosthesis as part of a separate trial. The mean duration of follow-up was 5.3 years (range, two to 8.5 years), and the patients were assessed with use of the Knee Society rating, a clinical anterior knee pain score, and the British Orthopaedic Association patient-satisfaction score. The assessment was performed without the examiner knowing whether the patella had been resurfaced. At the time of follow-up, there were 474 knees. Thirty-five patients who had a bilateral knee replacement underwent resurfacing on one side only. RESULTS: The overall prevalence of anterior knee pain was 25.1% (fifty-eight of 231 knees) in the nonresurfacing group, compared with 5.3% (thirteen of 243 knees) in the resurfacing group (p < 0.0001). There was one case of component loosening. Ten of eleven patients who underwent secondary resurfacing had complete relief of anterior knee pain. The overall postoperative knee scores were lower in the nonresurfacing group, and the difference was significant among patients with osteoarthritis (p < 0.01). There was no significant difference between the resurfacing and nonresurfacing groups with regard to the postoperative function score. Patients who had a bilateral knee replacement were more likely to prefer the resurfaced side. CONCLUSIONS: As the present study showed a significantly higher rate of anterior knee pain following arthroplasty without patellar resurfacing, we recommend patellar resurfacing at the time of total knee replacement when technically possible.     

髌骨软骨破坏程度对保留髌骨的全膝关节置换术疗效的影响

目的 探讨髌骨软骨破坏程度对保留髌骨的全膝关节置换术疗效的影响.方法 2002年1月至2006年5月行全膝关节置换术163例244膝,根据术中观察到的髌骨软骨破坏程度将患者分为轻度、中度、重度软骨破坏三组.所有手术均不置换髌骨.术后随访88例133膝,轻度组42膝,中度组43膝,重度组48膝.采用美国膝关节学会评分(Knee Society Score,KSS)系统(包括膝评分和膝功能评分)和膝前痛评分系统对三组疗效进行评估.结果 随访48～102个月,平均72个月.KSS膝评分和膝功能评分从术前(35.1±5.4)分和(19.2±9.8)分分别提高到(91.7±5.6)分和(83.7±17.5)分.三组KSS膝评分从术前(34.7±6.2)分、(36.5±5.2)分、(35.3±6.2)分分别提高至(92.6±4.5)分、(90.5±6.7)分、(91.9±5.9)分;膝功能评分从术前(14.2±8.6)分、(16.5±7.4)分、(17.0±7.5)分分别提高至(86.6±12.6)分、(82.0±17.2)分、(82.8±21.1)分.三组术后膝评分和膝功能评分的差异均无统计学意义.术后膝前痛的发生率为11.3%(15/133),轻度、中度、重度软骨破坏组分别为11.9%(5/42)、11.6%(5/43)、10.4%(5/48),差异无统计学意义.结论 全膝关节置换术后疗效及膝前痛的发生率与术前髌骨软骨破坏程度无关,髌骨软骨破坏程度不是全膝关节置换术中置换髌骨的可靠依据.

Abstract：

Objective To determine whether there was any correlation between the degree of degenerative changes in the patellar cartilage and the clinical outcome after TKA without patellar resurfacing.Methods A clinical study was performed on 133 knees of 88 patients that underwent TKA without patellar resurfacing from January 2002 to May 2006. According to the degenerative condition of the patellar cartilage,patients was classified as mild group, moderate group, and severe group. Pre- and post-operative evaluations were performed using the knee and function scores of the Knee Society Clinical Rating System (KSS) and Anterior Knee Pain Rating. Results The duration of follow-up was 72 months (range 48-102). The overall knee score of KSS in all patients were improved from 35.1±5.4 preoperatively to 91.7±5.6 postoperatively,and function score of KSS from 19.2±9.8 preoperatively to 83.7±17.5 postoperatively. The mean knee scores of KSS were improved from 34.7±6.2, 36.5±5.2 and 35.3±6.2 preoperatively to 92.6±4.5, 90.5±6.7 and 91.9±5.9 in mild, moderate, and severe group postoperatively, respectively. The mean function scores of KSS were improved from 14.2±8.6, 16.5±7.4 and 17.0±7.5 postoperatively to 86.6±12.6, 82.0±17.2 and 82.8±21.1 in mild, moderate, and severe group postoperatively, respectively. There was no difference among all groups with regard to the postoperative knee scores and function scores of KSS. The prevalence of anterior knee pain was 11.3% in all, and 11.9% in mild group, 11.6% in moderate group and 10.4% in severe group. There was no difference among all groups with regard to the anterior knee pain. Conclusion The clinical outcome and anterior knee pain after TKA without patellar resurfacing was not correlated with the severity of degenerative changes in the patellar cartilage. The degree of degenerative condition of the patellar cartilage is not indication for patellar resurfacing.     

Patelloplasty versus traditional total knee arthroplasty for osteoarthritis

The purpose of this study was to compare the clinical effects of patelloplasty and traditional patellar management in total knee arthroplasty (TKA) for osteoarthritis. A total of 152 patients with osteoarthritis treated with TKA between January 2004 and December 2005 were retrospectively studied. The patients were randomly divided into 2 groups: the patelloplasty group (group A; n=76) and the traditional treatment group (group B; n=76). Knee Society Score (KSS), Feller patellar score, Lonner patellar score, patient satisfaction, joint range of motion (ROM), and incidence of postoperative anterior knee pain were compared between the groups. Mean follow-up was 55 months (range, 48-71 months) for 132 patients, including 68 patients in group A and 64 in group B. Significant differences were found in KSS functional score, Feller patellar score, Lonner patellar score, and patient satisfaction, but no significant differences were found in ROM and total KSS score between the groups postoperatively. Group A obtained higher KSS scores and patient satisfaction than group B, with no significant difference in postoperative anterior knee pain. Postoperative radiographs revealed a significant difference in patellofemoral congruence between the groups. Patelloplasty relieves pain, enhances patient satisfaction, and improves function better than traditional patellar management in TKA with patellar nonresurfacing.     

Patella resurfacing in posterior stabilised total knee arthroplasty: a follow-up study in 56 patients

Patellar resurfacing in total knee arthroplasty (TKA) remains controversial. This study evaluates the results of resurfacing and non-resurfacing of the patella. Fifty-six patients with osteoarthritis (OA) of the knee were enrolled in a prospective randomised clinical trial using a posterior-stabilised TKA. Evaluations were done preoperatively and after 1, 3, 6, 12 and 24 months. Disease specific (Knee Society Score or KSS) and functional (patella-related activities) outcomes were measured. Patient satisfaction and anterior knee pain questionnaires were completed. No patients were lost to follow-up. No significant differences were found between groups with regard to the clinical part of the Knee Society score (KSS) not even in obese patients, the ability of performing daily activities involving the patellofemoral joint, and patient satisfaction. Significant differences were found regarding the functional section of the KSS, passive flexion, anterior knee pain and patellar tilt and subluxation. In conclusion, the authors believe that, for the implant studied, patellar resurfacing can be indicated.     

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BackgroundThe management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of this study is to evaluate the evidence regarding the use of patellar resurfacing in TKA.MethodsA meta-analysis of randomized controlled trials (RCTs) was performed to compare outcomes between knees receiving patellar resurfacing vs those not receiving resurfacing during primary TKA. Outcomes of interest were the Knee Society Scores, reoperation rates, anterior knee pain, patient satisfaction, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score subscores, and range of motion.ResultsTwenty RCTs met all eligibility criteria and were included in the analysis. There were statistically significant differences favoring the resurfaced group in the knee component and functional component of Knee Society Scores that were not clinically significant. There was an increased risk of reoperation among knees that did not receive resurfacing with number needed to treat to prevent one case of reoperation of 25 knees (for reoperation for any reason) and 33 knees (for reoperation for anterior knee pain). There were no statistically significant differences in any other outcomes.ConclusionThe only clear relationship is that knees that do not receive patellar resurfacing are more likely to receive reoperation, most often for secondary resurfacing. However, the disease burden of differing complication profiles associated with resurfacing and nonresurfacing groups remains unclear. Continuing to collect data from large, well-designed RCTs would be beneficial in guiding management of the patella during TKA.     

A meta-analysis of patellar replacement in total knee arthroplasty

From individual randomized studies it is unclear whether the patella should be replaced during total knee replacement. We did a meta-analysis to provide quantitative data to compare patellar resurfacing with nonresurfacing during total knee arthroplasty. Only randomized, controlled trials reported between January 1966 and August 2003 comparing patellar replacement with patella retention were included for a total of 12 studies. Two reviewers assessed trial quality and extracted data from papers. The outcomes identified were reoperations for patellar problems, anterior knee pain, knee scores, stair climbing, and patient satisfaction. The resurfaced patella performed better, and we found an increased relative risk (defined by the ratio of the risk of the event in the resurfaced group on the risk of the event in the nonresurfaced group) for reoperation, for significant anterior knee pain, and for significant pain during stair climbing when the patella was left unresurfaced. No differences were observed between the two groups for International Knee Society function score, Hospital for Special Surgery score, and for patient satisfaction. Despite these general findings, forming a definitive conclusion is difficult because many confounding factors, such as component design, surgeon experience, and technical aspects of the surgery, might influence the result in a patient.