The effect of a tourniquet on intraoperative patellofemoral tracking during total knee arthroplasty

A prospective investigation was performed on the effect of the tourniquet on intraoperative patellofemoral tracking during primary total knee arthroplasty (TKA). A total of 75 TKAs in 67 patients were performed by 1 surgeon in a consecutive series using the same technique. Using strict criteria, patellar tracking was assessed both before and after tourniquet release. Patients were placed into 1 of 3 groups: Group I were knees that tracked properly both before and after tourniquet release. Group II were knees that maltracked with the tourniquet inflated and subsequently corrected with the tourniquet released. Group III were knees that maltracked both before and after tourniquet release, therefore requiring a lateral release. Knees were categorized as group I, 34 of 75 (45.3%); group II, 36 of 75 (48.0%); and group III, 5 of 75 (6.7%). Using this criterion, lateral release was avoided in all group II knees. Tourniquet application alters intraoperative patellofemoral tracking during TKA. When contemplating lateral release, tourniquet deflation and reevaluation of patellofemoral tracking should be considered.     

全膝关节置换术中髌股轨迹的研究现状

髌股关节并发症是全膝关节置换术后翻修最常见的原因[1],多数表现为髌前痛及髌骨外侧半脱位[2-3],少数表现为髌骨骨折[4]、髌骨撞击综合征[5]、髌骨假体松动等。笔者就全膝关节置换术中髌股轨迹的研究现状综述如下。1解剖与生物力学髌股关节由髌骨关节面与股骨滑车沟及内外侧髁     

The patellofemoral component of total knee arthroplasty

Patellofemoral complications continue to form a large proportion (up to 50%) of total knee arthroplasty (TKA) complications. If adequate attention is paid intraoperatively to patellar tracking and component position, the incidence of subluxation, component loosening, and fracture should decrease. When treating patellar subluxation and dislocation, tibial tubercle transfer should be avoided because there is an unacceptably high incidence of complications. Care should be taken to treat the underlying cause of dislocation with either a soft tissue procedure or component revision. Fracture of the patella may be treated nonoperatively in 50% and 80% of patients. Cysts, if large, may be bone-grafted to avoid the potential complications of stress fracture and component loosening. Loosening of the patellar component is likely to be symptomatic and to require surgery in up to 75% of cases. A displaced patellar component may cause attritional wear of the quadriceps tendon or patellar ligament. All rheumatoid patellae should be resurfaced. The present trend in the osteoarthritic patella is toward resurfacing more often. With improved implant design and a predicted decrease in complications, resurfacing in the osteoarthritic patella may become routine. Osteoarthritic patellae that maintain good cartilage, normal anatomic shape, and congruent tracking need not be resurfaced.     

Early patellofemoral revision following total knee arthroplasty

A consecutive series of 289 Miller-Galante (Zimmer, Warsaw, IN) total knee arthroplasties were studied, with particular reference to the patellofemoral joint. Sixteen knees were initially excluded; the remaining 273 arthroplasties were followed for 14 to 44 months. Thirty patients (11%) had patellofemoral pain. Twenty patients (7.3%) had revision patellofemoral surgery. Fourteen patients had revision surgery for patellar maltracking, of which 10 had resolution of their symptoms, 2 were improved, 1 had no change, and 1 developed a prosthetic infection. Six patients who had no evidence of patellar maltracking had revision surgery with a cemented metal-backed patellar component. Only two of these patients had symptom improvement from their revision surgery. A higher than usual incidence of patellar maltracking (5%) is reported. The first-generation Miller-Galante femoral component may contribute to the relative instability of patellofemoral tracking. Those patients with patellar maltracking were greatly improved by revision surgery; the results of revision surgery for anterior knee pain without associated patellar maltracking were disappointing.     

髌股关节置换术与全膝关节置换术治疗单纯髌股关节骨关节炎的Meta分析

目的目的比较髌股关节置换术（PFA）与全膝关节置换术（TKA）治疗单纯髌股关节骨关节炎（PFOA）的失败率,评价两种不同治疗选择的疗效差异。方法检索Medline、Embase、CBM数据库,收集单纯髌股关节骨关节炎（PFOA）行PFA或TKA的临床试验,提取数据,采用Meta—Analyst3．13进行Meta分析。结果纳入39个回顾性临床试验,髌股关节置换1599膝,全膝关节置换患267膝。总的PFA组（包括第一代、第二代PFA）失败率13．6％[95％CI（0．103,0．176）];TKA组失败率1．8％[95％CI（0．007,0．044）];第一代PFA假体失败率19％[95％CI（0．143,0．247）];第二代PFA假体失败率8．3％[95％CI（0．053,0．128）]。结论PFOA患者行PFA的失败率比TKA高,需要再手术或翻修,这与假体设计和适应证的选择有关。第二代PFA假体翻修率与第一代相比明显降低。     

The effect of surgical approaches and tourniquet application on patellofemoral tracking in total knee arthroplasty

The purpose of this study was to assess the influences of surgical approaches and tourniquet application on the lateral retinacular tension (LRT). Single-setting bilateral total knee arthroplasty was performed in 10 patients, and the medial parapatellar and midvastus approaches were randomly performed on each knee using tourniquet application. The LRT was measured using the buckle transducer before and after each approach. Next, the tourniquet was deflated and the measurement was repeated. After the parapatellar approach, LRT was significantly decreased. Conversely, no significant change was seen after the midvastus approach with the tourniquet inflated. However, in the midvastus approach, LRT was significantly decreased after tourniquet deflation. We concluded that both the parapatellar and midvastus approaches influence patellar tracking and LRT.     

Revision of a failed patellofemoral arthroplasty to a total knee arthroplasty

BACKGROUND: Patellofemoral arthroplasty is an effective treatment for isolated arthritis of the anterior compartment of the knee, but it is unclear whether it compromises the results of total knee arthroplasty if revision is necessary. The purpose of this study was to review the results of total knee arthroplasty after a prior patellofemoral arthroplasty. METHODS: Twelve failed patellofemoral replacements in ten patients were revised to total knee arthroplasties for isolated progressive tibiofemoral arthritis (six knees), isolated patellofemoral catching and maltracking (three), or a combination of both (three). Revisions were performed at a mean of four years after the patellofemoral arthroplasty. A posterior stabilized implant was used in each knee, without a need for stems, augments, or structural bone graft. Patients were assessed by clinical and radiographic follow-up, including Knee Society clinical and functional scores. Baseline preoperative Knee Society scores were obtained at the time of evaluation of the failed patellofemoral arthroplasty. RESULTS: At a mean follow-up of 3.1 years, the mean Knee Society clinical and functional scores had increased from 57 points preoperatively to 96 points and from 51 points preoperatively to 91 points, respectively. At the most recent follow-up, there was no clinical or radiographic evidence of patellofemoral maltracking, loosening, or wear. CONCLUSIONS: On the basis of our experience in this relatively small series with short-term follow-up, the results of total knee arthroplasty do not seem to be compromised after revision of the failed patellofemoral replacement.     

Kinematics of the patellofemoral joint in total knee arthroplasty

Sagittal plane patellofemoral kinematics was determined for 81 subjects while performing a weight-bearing deep knee bend under fluoroscopic surveillance. Fourteen normal knees, 12 anterior cruciate ligament (ACL)-deficient knees, and 55 total knee arthroplasties (TKAs) were assessed. Of TKAs, 39 had resurfacing with a dome-shaped patella, 8 had resurfacing with an anatomic mobile-bearing patella, and 8 were unresurfaced. TKA patellae experienced more superior patellofemoral contact and higher patellar tilt angles compared with the normal knees and ACL-deficient knees (P <.05). Patellofemoral separation at 5 degrees (+/-3 degrees ) extension was seen in 86% cruciate-retaining and 44% cruciate-stabilized TKAs and 8% ACL-deficient knees but not in the normal knees or mobile-bearing TKAs (P <.05). The patellar kinematic patterns for subjects having a TKA were more variable than subjects having either a normal knee or an ACL-deficient knee. Kinematic abnormalities of the prosthetic patellofemoral joint may reduce the effective extensor moment after TKA.     

Patellofemoral arthroplasty versus total knee arthroplasty in patients with isolated patellofemoral osteoarthritis

We identified all patients at our institution who underwent patellofemoral arthroplasty (PFA) or total knee arthroplasty (TKA) as treatment for isolated patellofemoral arthritis (PA) between January 2003 and December 2005. Twenty-three PFA and 22 TKA patients met inclusion criteria. Mean age was 60 years and 69 years, respectively (P = .01). Mean follow-up was 29 months (range, 24 to 49 months) in the PFA group and 27 months (range, 24 to 33 months) in the TKA group. Mean postoperative Knee Society Clinical Rating System scores were 89 and 90 in the PFA and TKA cohorts, respectively. Mean UCLA scores were 6.6 and 4.2, respectively (P<.0001). Mean blood loss (P = .03) and hospital stay (P = .001) were significantly lower among PFA patients. Linear regression analysis showed that blood loss, hospital stay, and functional outcomes were not affected by age as an independent variable. No significant complications occurred in the PFA group. There was one deep vein thrombosis in the TKA group. We conclude that PFA yields clinical outcomes comparable to that of TKA as treatment for isolated PA and may be a less invasive option for this select subgroup of patients.     

全膝关节置换术中放开止血带并缝合内上缘支持带对髌骨轨迹的影响

目的 探讨在初次全膝关节置换术(TKA)中放开止血带且缝合内上缘支持带对髌骨轨迹的影响.方法 选择2006年3月至2008年2月初次行TKA的83例患者136侧膝关节.使用前内侧髌旁人路,检测髌骨轨迹.对于不良的髌骨轨迹,术中松开止血带且仅用一针缝合髌骨内上缘支持带.再次检查髌骨轨迹.最后,对残留不良髌骨轨迹的患者行外侧支持带松解术,以求获得满意的髌骨轨迹.采用no-thumb试验作为检测髌骨轨迹的标准.结果 在初次行TKA的83例患者136侧膝关节中,在未松开止血带前,髌骨轨迹不良率为64.7%(88/136).放开止血带且缝合髌骨内上缘支持带后,髌骨外侧支持带松解率为26.5%(36/136),差异有统计学意义(X2=38.55,P＜0.01).其中,膝外翻畸形患者的松解率为58.6%(17/29),膝内翻和无明显畸形患者的松解率为17.8%(19/107).结论 高压止血带对行前内侧髌旁人路TKA的患者髌骨轨迹的干扰作用非常明显.术中松开止血带且缝合髌骨内上缘支持带明显降低了外侧支持带的松解率,从而降低了其可能带来的并发症.     

The patellofemoral joint after total knee arthroplasty without patellar resurfacing

One hundred total knee replacements with a total condylar prosthesis and without patellar resurfacing were followed for a minimum of two years. Eighty-four per cent of the knees were affected by osteoarthrosis. Graded according to the knee-rating system of the Hospital for Special Surgery, there were eighteen excellent, fifty-three good, eighteen fair, and eleven poor results. At the most recent follow-up, twenty-nine knees (29 per cent), nine of which were affected by rheumatoid arthritis, were still painful in the patellofemoral area. The height and weight of the patient definitely influenced the amount of patellofemoral pain postoperatively. Small patients who had osteoarthrosis were exceptionally free of pain, regardless of sex, age, or level of activity. It seems that the best approach to patellofemoral replacement includes resurfacing of the patella in all patients who have rheumatoid arthritis and in patients who have osteoarthrosis if they have preoperative patellofemoral pain, are more than 160 centimeters tall, weigh more than sixty kilograms, and have advanced changes in the patella at the time of the operation.     

The effect of built-in external femoral rotation on patellofemoral tracking in the genesis II total knee arthroplasty

External rotation of the femoral component during total knee arthroplasty (TKA) has been suggested to improve flexion space balancing and patellofemoral tracking. Incorporation of external rotation into the design of the femoral component offers an alternative method to achieve this goal. This study compared 150 TKAs performed with traditional external rotation of the femoral component on the distal femur with a similar group of 150 TKAs performed with an implant that incorporates 3 degrees of external rotation into the femoral component. Statistical improvements were noted in the latter group, with respect to the need for intraoperative lateral retinacular release and in postoperative patellar tracking. Incorporation of 3 degrees of external rotation into the design of the femoral component seems to improve the overall result of TKA, especially with respect to patellofemoral resurfacing.     

Factors affecting patellar tracking after total knee arthroplasty

This study examined factors that influence patellar tracking after total knee arthroplasty. A total of 62 knees were evaluated radiographically for postoperative patellar tracking. Six factors were examined regarding their influence on postoperative patellar tracking. This study showed the effects of patellar component position, patellar resection angle, and lateral retinacular release on postoperative patellar tracking. There was no significant effect of the remaining 3 factors: the thickness of the patellar resection, preoperative patellar tilt, and rotational alignment of the femoral component. A medialized patellar component and obliquity of resection of the patella are effective for obtaining proper patellar tracking, whereas the evaluation of the influence of the external rotation of the femoral component requires more clinical studies.     

Optimizing femoral component rotation in total knee arthroplasty.

Femoral component rotation is important in total knee arthroplasty to optimize patellofemoral and tibiofemoral kinematics. More recently, the epicondylar axis has been cited as the definitive landmark for femoral component rotation. However, there are few studies to support the validity of this rotational landmark and its effect on the patellofemoral and tibiofemoral articulations. In the current study, a total knee arthroplasty was done in 11 knees from cadavers. The knees were tested with various femoral component rotations from 5 degrees internal rotation to 5 degrees external rotation referenced to the epicondylar axis and to the posterior femoral condyles. Each knee acted as its own internal control. The knees were actively ranged from 0 degrees to 100 degrees by a force on the quadriceps tendon in an Oxford knee simulator. Three-dimensional kinematics of all three components were measured whereas a multiaxial transducer imbedded in the patella measured patellofemoral forces. Femoral component rotation parallel to the epicondylar axis resulted in the most normal patellar tracking and minimized patellofemoral shear forces early in flexion. This optimal rotation also minimized tibiofemoral wear motions. These beneficial effects of femoral rotation were less reproducibly related to the posterior condyles. Rotating the femoral component either internal or external to the epicondylar axis worsened knee function by increasing tibiofemoral wear motion and significantly worsening patellar tracking with increased shear forces early in flexion. Based on the current study, the femoral component should be rotationally aligned parallel to the epicondylar axis to avoid patellofemoral and tibiofemoral complications.     

Radiographic evaluation of patellofemoral alignment in kinematically aligned total knee arthroplasty: A comparative study with mechanically aligned total knee arthroplasty

BackgroundKinematically aligned total knee arthroplasty (KA-TKA), in which femoral component is placed 3–5° of internal rotation relative to mechanically aligned (MA)-TKA, may have a potential risk of patellofemoral malalignment. This study aimed to assess patellofemoral alignment and compare the data between KA-TKA and MA-TKA, and the relationship with patellofemoral radiographic parameters and patient reported outcomes.MethodsAmong patients who underwent TKA in 2015 and 2016 in our institute, 28 KA-TKAs with a metal-backed patellar component were retrospectively assessed for patellofemoral alignment, and 28 MA-TKAs with a metal-backed patellar component served as controls. A year postoperatively, patellar tilt and shift at 30°, 60°, and 90° knee flexion were measured on Merchant views and compared between the two TKAs. Implant positioning in each patient was assessed based on preoperative CT images and correlations of femoral component positioning with patellar tilt/shift were assessed.ResultsPatellar shift at 30° flexion was significantly greater in KA-TKA than in MA-TKA (p = 0.04), whereas patellar tilt angle was comparable between the two TKAs. No statistical correlation was evident between femoral component positioning and patellar shift/tilt, regardless of knee flexion angle in the two TKAs. Knee Society Score 2011 at 1 year follow-up was comparable in all subcategories between the two TKAs.ConclusionRadiographic analysis of KA-TKA revealed lateral shift of the patella at 30° knee flexion at 1 year postoperatively, however patients with patellar shift were asymptomatic. Further long-term observation is required to examine the impact of KA-TKA on the patellofemoral complication.     

全膝关节置换术术中注射类固醇激素的系统评价（英文）

[目的]对TKA术中类固醇激素注射的有效性及安全性进行评价。[方法]计算机检索Pubmed(1966~2014.5),EMBASE(1984~2014)及Cochrane Library等数据库,搜集有关TKA术中是否增加类固醇激素注射的RCTs,比较TKA术后的疗效及安全性。2名研究者独立筛选文献并提取数据,使用Cochrane Handbook 5.1对文献质量进行严格评估。[结果]8篇RCT共纳入503例患者。研究结果显示:TKA术中注射类固醇激素能够降低VAS评分、CRP水平、PONV发生率及吗啡消耗量,缩短住院时间并提高早期ROM(P0.05),而在术后并发症方面两者未表现出显著性差异(P0.05)。[结论]目前的证据表明,TKA术中类固醇激素注射可以控制炎症、减少术后疼痛及恶心呕吐的发生,增加患者早期关节活动度并缩短住院时间,且不会增加术后并发症的风险。此外,类固醇激素注射的最佳剂量和长期效果仍需更多的研究去验证。     

Effect of patellar meniscus on patellofemoral contact stress in total knee arthroplasty

The effect of a meniscus of fibrous tissue (patellar meniscus), on patellofemoral contact area and stresses was evaluated. Two knees with total knee arthroplasty and dome-shaped patellar components were retrieved at autopsy. Both had substantial fibrous menisci surrounding the dome of the patellar component. Contact area and contact stresses were measured with a digital electronic sensor, first with the patellar meniscus intact, then again after the patellar meniscus was removed. No dramatic difference was detected in patellofemoral contact area and contact stresses between the patellas with an intact or removed patellar meniscus, and there was no detectable load under the patellar meniscus. The results of this case study suggest that fibrous tissue surrounding the dome-shaped patellar component does not share compressive loads with the patellar component.