Radiographic changes in the patella following quadriceps turndown for revision total knee arthroplasty

Quadriceps turndown is a technique that may be used to enhance exposure of the tight total knee arthroplasty (TKA), particularly in the revision scenario. This technique does, however, compromise the vascularity of the patella, with avascular necrosis (AVN) being a possible sequela. A modified Coonse-Adams quadriceps turndown was performed in 29 revision TKAs in 27 patients. Immediate preoperative and sequential postoperative radiographs were analyzed for changes in the patella, including sclerosis, flattening, fracture, and fragmentation, as evidence of possible AVN, and clinical scores were collected prospectively. Eight patellae had such radiographic changes. Despite a lack of corresponding worsening in clinical outcome in these patients, quadriceps turndown is shown to have a high risk of subsequent changes consistent with patellar AVN, and should be avoided when other available techniques can achieve satisfactory exposure.     

全膝关节置换翻修术中骨缺损的处理

全膝关节翻修术中导致骨缺损的因素很多,包括松动假体的沉降、应力遮挡效应、假体周围骨溶解、坏死及感染等。对于骨缺损处理方法的选择,应综合考虑缺损区的大小及位置,患者的年龄、健康状况以及参与术后康复训练的能力等多方面因素。1骨缺损的分型骨缺损可分为包容性和非包容性骨缺损。包容性骨缺损周围仍有完整的骨皮质进行包绕,翻修时可通过颗粒骨植骨或骨水泥螺钉技术进行处理;而非包容性骨缺损周围的骨皮质部分会全部丧失,通常需要通过组培式垫块、结构性植骨、干骺端金属袖套或锥形套进行重建。     

Use of a trabecular metal patella for marked patella bone loss during revision total knee arthroplasty

This study evaluates the short-term results following patellar resurfacing with a trabecular metal patella shell in the setting of marked patellar bone loss at the time of revision total knee arthroplasty (TKA). Twenty consecutive patients undergoing revision TKA with the use of a trabecular metal patella were evaluated at a mean 23-month follow-up. All patients had marked patellar bone loss at surgery precluding resurfacing with a standard cemented patellar button. Results were good or excellent in 17 of 20 patients. There were no displacements of any trabecular metal patella shells, and the fixation appeared excellent despite the poor quality of bone remaining. Complications included 3 patients with polar patella fractures postoperatively. Qualitatively, these results compare favorably with patellar resection arthroplasty in this setting.     

Medialization of the patella in total knee arthroplasty

Patellar complications of total knee arthroplasty remain the most common cause of pain and reoperation. Laboratory studies have suggested that medialization of the patella will improve tracking of the patella on the trochlea of the femoral component. The purpose of this study was to determine if clinical medialization of the patellar component on the patellar bone would improve tracking of the patella as demonstrated radiographically. Sixty-two knees were randomized so that 31 knees had a centrally placed patellar component and 31 had the patellar component placed on the medial two thirds of the patellar bone. There was no difference between the two groups with respect to either clinical or radiographic results in the first year after surgery. There was no improvement compared with previous reports in the incidence of tilt and displacement. The one improvement was a reduction in the incidence of lateral release. Thus, consequences of lateral release such as postoperative morbidity, avascular necrosis of the patella, and stress fracture of the patella can be avoided. It is recommended that the patellar component be placed on the medial two thirds of the patella to reduce the occurrence of lateral release. Tracking of the patella during surgery can be assessed using a single suture placed at the superior pole of the patella, and this technique in combination with the no-thumbs test provides an additional means of evaluation for patellar tracking.     

全膝关节置换术中髌骨处理

全膝关节置换术中是否进行髌骨置换仍有争论,术后膝前疼痛及髌股关节并发症是争论的焦点.膝前疼痛是多种因素共同作用的结果,不能简单地归咎为髌骨置换与否.全膝关节置换时是否置换髌骨应考虑原发病、病变程度、假体类型及患者活动量和体重等诸多因素.如果行髌骨置换,精湛的外科技术、合适的假体是全膝关节置换术后髌股关节并发症减少的关键;如果不行髌骨置换,患者的筛选标准是保证手术疗效的关键.     

Rotating-hinge total knee for revision total knee arthroplasty

Rotating-hinge knee implants are used for revision total knee arthroplasty in patients with severe ligament instability and bone loss. This study evaluated the outcomes of a series of rotating-hinge knees. Thirty-one NexGen Rotating Hinge Knees (Zimmer, Warsaw, Indiana) were implanted in 29 patients (2 bilateral), with an average age of 72.8 years. Indications for surgery were aseptic loosening (n=23), septic loosenings (n=4), tibiofemoral instability (n=3), and wear (n=1). The Hospital for Special Surgery Knee Score and the Knee Society Roentgenographic Evaluation System were used. Statistical and cumulative survival rate analyses were performed. Average follow-up was 60.3 months (range, 32-100 months). The Hospital for Special Surgery Knee Score results indicated statistically significant improvement; the total score increased from 65.5 preoperatively to 88.4 postoperatively. Average range of motion increased from 90.9° preoperatively to 114.4° postoperatively. Radiographs showed no periprosthetic bone fractures or implant ruptures. Radiolucent lines were found in 20 of 26 patients and were progressive in 2 (both revised). Complications occurred in 10 patients. The rigidity of the hinge may be associated with a risk of aseptic loosening due to the increased stress transfer to the bone from the prosthesis through the locked hinge. Rotating-hinge knee implants provided acceptable mid-term outcomes for revision knee surgery with ligamentous instability. They are not at higher risk for early loosening unless short tibial stems are used. The high percentage of failures is more related to the complex surgery and to the status of the patients than to the hinged mechanism.     

全膝关节置换翻修术中保留与非保留髌骨假体的Meta分析

目的通过Meta分析,比较全膝关节置换翻修术（RTKA）中髌骨假体保留与否的疗效差异。方法全面检索国内外关于RTKA中与是否保留髌骨假体疗效相关的文献,经特定的纳入、排除标准筛选文献,提取临床评分、功能评分、SF躯体及心理评分、患者满意度等相关数据后,采用Review Manager（Rev Man）4.2.10软件进行Meta分析。结果纳入随机对照研究3篇,共计231例RTKA患者,其中保留髌骨假体组共154例,非保留髌骨假体组共77例。Meta分析结果显示,保留髌骨假体组的临床评分（P=0.91）、功能评分（P=0.35）、SF躯体（P=0.39）及心理评分（P=0.13）与非保留组差异均无统计学意义。结论 RTKA术中髌骨假体的保留与否对术后症状改善、功能恢复等无明显的影响。     

Asymmetric patella resurfacing in total knee arthroplasty

Three hundred consecutive primary, cemented, condylar total knee arthroplasties (TKAs) were reviewed for the presence of asymmetric patella resurfacing using a postoperative Merchant or sunrise patellar radiograph. Twenty-one knees in 14 patients were found to have the patella asymmetrically resurfaced. Asymmetric resurfacing typically involved the inadvertent preferential resurfacing of the lateral facet with underresection of bone from the medial patellar facet. All patients underwent follow-up for a minimum of 5 years, with a mean follow-up of 7.5 years. Of the 21 knees, 3 revisions were required for patellar complications. One patellar component was loose on radiographs and there was marked patellofemoral pain in 6 knees. Overall, 11 of 21 knees (52%) underwent revision or were recommended for revision for patellar complications or had anterior knee pain that limited activities. Inadvertent asymmetric patella resurfacing using the kinematic condylar implant adversely affects the outcome after TKA.     

The patella in total knee arthroplasty.

Controversy persists as to whether the patella should be resurfaced in total knee arthroplasty. Can the good results of patellar cartilage against the metal femoral component be expected to endure? Attention to technique can be expected to reduce some of the complications of resurfacing, notably fracture, rupture, and instability. Component breakage results from metal-backed designs, and the causes of patellar clunks have not been fully understood.     

Fracture of the patella following total knee arthroplasty

The charts of 21 patients (22 knees) with significant radiographic changes of the patella after total knee arthroplasty were reviewed. The average patient age was 73 years, and average follow-up after arthroplasty was 7.3 years. Lateral release, fat pad excision, quadriceps tendon release, and previous surgery were implicated in the etiology of fracture of the patella. Five cases had type 1 pattern (sclerosis, fragmentation, and no fracture), 5 cases had type 2 pattern (undisplaced fracture and fragmentation), and 12 cases had type 3 pattern (displaced fracture and fragmentation). Type 1 and 2 patterns required no surgical treatment and were rated good to excellent according to the Hospital for Special Surgery Disability Score Sheet. Patients with a type 3 pattern who did not undergo surgery were rated poor to fair, while patients with a type 3 pattern who underwent surgical treatment (patellectomy, removal of the patellar component, or excision arthroplasty for infection) were rated good. Patellectomy is the treatment of choice for patients with displaced fractures of the patella. A classification system for the pattern of patellar changes is proposed.     

Management of recurrent dislocation of the patella following total knee arthroplasty.

Fifteen knees with patellar dislocation after total knee arthroplasty had realignment of the extensor mechanism using a modification of the Trillat procedure. The onset of dislocation occurred on average 4.7 months from the time of surgery. After total knee arthroplasty the patients had an average range of motion of 109 degrees. All patients had medialization of the tibial tubercle and lateral release. No patient had a recurrent dislocation after a minimum 2-year follow-up period. The average knee score was 82 and the average flexion arc was 112 degrees. All but one of the osteotomies healed uneventfully.     

Fracture of the patella after total knee arthroplasty

Patellar fracture after knee arthroplasty was found in 11 patients (12 knees) during a 15-year period. Causes of this fracture include trauma, technical factors, and biophysical factors. The incidence of this infrequent complication was significantly increased after patella resurfacing and revision arthroplasty. Minimally displaced, non-comminuted fractures were immobilized, whereas displaced, comminuted fractures with loose patellar prostheses were treated operatively. At a mean follow-up period of 28 months, the average knee score was 75 points. The average arc of motion was 87 degrees, and six of the 11 patients have returned to their prefracture functional level. Treatment should be individualized on the basis of fracture displacement, comminution, and button fixation.     

人工全膝关节感染翻修医疗费用相关性调查

目的探讨人工全膝关节感染翻修医疗费用中的各项组成与手术方式的相关性，为人工全膝关节感染翻修方式的选择提供参考。方法统计2000年到2010年于本组因感染行人工全膝关节翻修术的患者，并按纳入标准选取符合要求的患者23例，男5例，女18例；年龄50～85岁，平均66．6岁。分析并比较其围手术期发生相关费用组成，同时选取同期年龄、性别、基础疾病匹配的初次人工关节置换患者，并对一期、二期翻修及初次人工关节置换进行费用对比，应用SPSS16．0统计软件对数据进行处理。结果23例患者翻修手术的平均费用为（98736．94±44330．23）元，一期翻修住院时问及治疗费用明显较二期翻修者少，差异具有统计学意义（t=2．84，P〈0．05；t=2．94，P〈0．05）；与初次膝关节置换相比，翻修手术住院13及翻修费均明显增加，差异具有统计学意义（t=7．165，P〈0．05；t=5．678，P〈0．05）。翻修手术中更换部分关节假体组件的翻修方式较全部更换更为经济，但风险更大。翻修假体及围手术期抗生素的应用仍然是整个医疗费用中最大的部分，占整个治疗疗费用77．42％。结论膝关节感染是膝关节置换术后翻修的重要原因，选择合适的治疗方式和手术方案可以极大的减少医疗费用的消耗。     

Pseudoaneurysm after revision total knee arthroplasty

Arterial vascular complications following knee replacement are uncommon with reported incidence ranging from 0.03 to 0.12%. The complication rate is rising with increased number of primary and revision total knee replacements. Vascular complications following TKR can result in arterial thrombosis, AV fistula, haemorrhage, pseudoaneurysm and arterial transection. They are associated with significant morbidity and can be limb-threatening. Early recognition and management of vascular injury is essential although some times its presentation may be delayed. We report a case of pseudoaneurysm arising from inferior lateral genicular branch of the anterior tibial artery after revision right total knee replacement.     

Cemented long-stem revision total knee arthroplasty

From 1981 to 1989, 38 cemented, posterior, stabilized, revision, total knee arthroplasties (TKAs) were performed at the authors' institution using the stemmed kinematic stabilizer prosthesis of a single design. The mean clinical follow-up after the index procedure was 10.1 years. The Knee Society pain score averaged 17 points before revision and improved to 51 points at last follow-up, and the function score averaged 48 points before revision and improved to 57 at last follow-up. Ten-year component survival free of revision or removal for any reason was 96.7%; 11-year component survival free of revision for aseptic loosening was 95.7%. Cemented stem fixation in revision TKA provides good clinical results with durable fixation at an average of 10 years' follow-up.     

Rotating platform revision total knee arthroplasty

Although revision total knee arthroplasty (TKA) procedures are successful in relieving pain and restoring function in failed knees, long-term results are inferior to primary procedures. Mobile bearing (MB) revision knees can potentially improve functional performance. Clinical results of 44 MB rotating platform (RP) revision TKAs demonstrated mean knee injury and osteoarthritis outcome score (KOOS) activity of daily living score of 77 2 years postoperatively. Clinical results were put into context through wear testing which demonstrated improved wear performance compared with fixed bearing (FB) revision knees. The RP construct is a good choice for revision TKA because it permits the surgeon to align the tray for fixation, not compromise rotation of the tibial insert, and reduce transmission of shear stresses to the bone, cement and implant interface, which is a known cause of failure.     

Endosteal referencing in revision total knee arthroplasty

A method of orienting the femoral and tibial bone cuts relative to the endosteal cortex of the femur and tibia was used in 32 patients who underwent revision total knee arthroplasty. The mean orientation of the femoral component was 96.74° ± 1.03°, mean orientation of the tibial baseplate was 90.71° ± 1.10°, mean anatomic tibiofemoral alignment was 7.42° ± 1.69° of valgus, and mean mechanical tibiofemoral alignment was 1.09° ± 1.83° of valgus. Mean tibial bowing was 1.63° ± 1.57° of valgus, and mean femoral bowing was 0.58° ± 1.53° of varus. Valgus tibial bowing was correlated with valgus orientation of the tibial component (r = .86, P < .000001), and varus femoral bowing was correlated with orientation of the femoral component (r = .54, P = .0054). Referencing the implant position from the endosteal cortex of the intramedullary canals provides a reliable method of achieving satisfactory alignment in most revision total knee arthroplasties; however, bowing of the femur or tibia can affect alignment.