Bone-grafting for severe patellar bone loss during revision knee arthroplasty

BACKGROUND: Severe patellar bone loss may preclude adequate fixation of another patellar prosthesis as a part of revision knee replacement. The purpose of this study was to describe the surgical technique and early clinical results of an alternative to the conventional treatment options of either patellectomy or retention of the remaining patellar osseous shell. The goals of this procedure are to restore patellar bone stock and potentially to improve the functional outcome. METHODS: Severe patellar bone loss had left a "patellar shell" that precluded insertion of another patellar implant in nine of 100 consecutive knees undergoing revision total knee arthroplasty. Rather than performing a patellectomy or simply retaining the patellar osseous shell in these nine knees (eight patients), I performed a surgical procedure in which a tissue flap was secured to the patellar rim to contain cancellous bone graft inserted into the patellar bone defect. Final follow-up was at a mean of 36.7 months (range, twenty-four to fifty-five months) after the patellar bone-grafting procedure. RESULTS: The mean preoperative Knee Society scores for function and pain were 39 points (range, 18 to 82 points) and 40 points (range, 20 to 80 points), respectively. At the time of final follow-up, the Knee Society function and pain scores had improved significantly, to a mean function score of 91 points (range, 80 to 98 points) and a mean pain score of 84 points (range, 65 to 100 points) (p<0.05). The point of greatest patellar thickness measured intraoperatively ranged from 7 to 9 mm. Patellar thickness on immediate postoperative Merchant radiographs averaged 22 mm (range, 20 to 25 mm) whereas, at the time of final follow-up, patellar thickness averaged 19.7 mm (range, 17 to 22.5 mm). CONCLUSIONS: In contrast with other treatment alternatives, this surgical procedure imparts the potential for restoring patellar bone stock and may improve functional outcome by facilitating patellar tracking and improving quadriceps leverage. On the basis of satisfactory short-term to mid-term clinical results, this technique of patellar bone-grafting appears to be an important addition to the armamentarium of surgeons performing revision knee arthroplasties.     

Management of large bone defects around the knee using porous tantalum trabecular metal cones during complex primary and revision total knee arthroplasty

With the rising numbers and indications of primary as well as revision total knee arthroplasty (TKA), managing bone defects around the knee is an emerging challenge. This retrospective study evaluates the outcomes of Trabecular Metal (TM) cones used to address bone defects in 79 (20 primary and 59 revision) TKA cases. Range of motion and Knee Society Score improved significantly postoperatively, with better outcomes in the primary TKA group. Complete osteointegration was observed in all the cases. At an average follow-up of 6.6 years, major complications requiring re-operation were seen in 4 (5%) knees. TM cones are an effective option for treating severe bone defects during TKA with predictable osteointegration and good long-term clinical outcomes.     

Management of the patella in revision total knee arthroplasty

Problems with the patellofemoral joint comprise the most common complication in primary and revision total knee arthroplasty (TKA). The difficulties can range from instability and anterior knee pain at one end of spectrum of severity, to fracture and extensor mechanism disruption at the other end. These complications are generally higher in revision TKA due to compromised bone stock and blood supply. Despite the particular challenges posed by the bone-deficient patella, reasonable results can be achieved.     

Review article: Treatments for bone loss in revision total knee arthroplasty

Bone deficiency hinders implant alignment and stabilisation of the bone-implant interface in revision total knee arthroplasty (TKA). Treatments for bone defects include bone cement, bone cement with screw reinforcement, metal augments, impaction bone grafts, structural allografts, and tantalum, depending on the location and size of the defects. Small defects are usually treated with cement, cement plus screws, or impaction allograft bone. Large defects are repaired with structural allografts or metal augments. Recent developments involve the use of highly porous osteoconductive tantalum. We reviewed the pros and cons of each method for bone defect management in revision TKA.     

Results of revision total knee arthroplasty associated with significant bone loss

The results of 40 revision total knee arthroplasties (TKAs) in 38 patients performed for aseptic failure with significant bone loss were reviewed. All knees were evaluated for at least two years, with an average of 41 months (range, two to nine years.) Seventy-five percent of the knees were considered excellent or good. Ten percent were considered failures. There were no infections. Overall complication rate was 30%, of which wound complications were the most common. Revision TKA remains demanding, but results can be improved by (1) restoring the mechanical alignment of the knee with accurate component positioning; (2) filling all bone defects with bone, cement, or modular spacers; (3) using stems to assist in component support; and (4) adherence to soft-tissue balancing and care.     

Cementless reconstruction of massive tibial bone loss in revision total knee arthroplasty

Reconstruction of massive proximal tibial defects caused by failed cemented total knee arthroplasty (TKA) was evaluated using cancellous allograft and a rigidly fixed tibial component. Twenty patients with massive tibial defects requiring revision TKA were operated on using this technique from December 1984 to December 1986. All these had tight mediolateral capsular structures so that satisfactory varus-valgus stability was achieved. Only three had competent posterior cruciate ligaments. The tibial component had a cobalt chromium tray with a six-inch-long smooth stem, porous undersurface, and peripheral smooth pegs. Fixation was augmented with four cancellous screws that passed through the periphery of the tray and penetrated the cortical surface of the tibia. Good fixation of the tibial component was achieved in all cases at the time of surgery. All patients achieved full weight bearing within six months, and all but two were free of walking aids at one year postoperation. None of the patients developed apparent loosening of the femoral or tibial components. Two patients complained of mild pain and one who had revision of a painful but nonloosened cemented TKA complained of severe pain. Range of motion was 93 degrees +/- 7.6 degrees. Roentgenographic evaluation showed progressive increase in radiodensity in the grafted areas one year after surgery in all knees. One knee was revised for recurrent dislocation one year postoperation and had a biopsy of the allografted area. This biopsy showed trabeculae with empty lacunae surrounded by viable new bone. Allograft reconstruction of the proximal tibia for failed cemented TKA was highly successful using morselized allograft and rigid fixation of the tibial component.(ABSTRACT TRUNCATED AT 250 WORDS)     

全膝关节翻修术中应用金属垫片修复非包容性骨缺损的中期随访

目的探讨在全膝关节翻修术中采用金属垫片修复股骨及胫骨侧非包容性骨缺损的临床效果。方法对1992~2001年间227例全膝关节翻修术中使用金属垫片修复AORI-Ⅱ型非包容性骨缺损而获得随访的62例患者进行回顾性分析,男28例,女34例;年龄42~87岁,平均67.8岁;假体松动翻修30例,感染后假体二期植入19例,假体周围骨溶解3例,假体位置、下肢力线不佳或关节不稳定10例。采用金属垫片来修复骨缺损及恢复关节线水平,并使用髓内假体柄来增加翻修假体的稳定性。结果术后随访13~132个月,平均60.8个月。根据膝关节协会评分,膝评分从术前平均25分(15~60分)增加到随访时的平均76分(30~95分);功能评分从术前的40分(15~65分)增加到随访时的62分(25~90分);膝关节活动度从术前的78°(30°~100°)增加到随访时的87°(40°~130°)。2例感染后二期假体植入的病例由于感染复发而失败。11例股骨后侧、4例胫骨内侧可见金属垫片下骨水泥与骨界面有透亮带,但均未呈进行性发展。结论采用金属垫片修复全膝关节翻修术中非包容性骨缺损,尤其适用于老年患者,既可以方便手术操作,获得即刻稳定性,又可以提高翻修成功率。     

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.     

Distal femoral allograft reconstruction for massive osteolytic bone loss in revision total knee arthroplasty

Massive osteolytic bone loss in revision total knee arthroplasty has been an uncommon challenge. From 2001 to 2002, 11 knees in 10 patients underwent revision of failed modular PFC (Johnson and Johnson Orthopaedics, Raynham, Mass) total knee arthroplasties with distal femoral allografts and long-stemmed revision implants for massive osteolytic induced femoral bone loss. The mean follow-up was 42 months (range, 36-48 months). Radiographic graft incorporation was demonstrated in all 11 knees with no cases of loosening. The Knee Society Pain Scores improved by an average of 25.4 points, and the function scores improved by an average of 23.3 points. The outcomes of distal femoral allografts in the reconstruction of massive osteolytic bone loss associated with failed modular PFC (Johnson and Johnson Orthopaedics) total knee arthroplasties are favorable.     

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.     

Accurate preparation of the patella during total knee arthroplasty

The development of a resection guide that facilitates accurate preparation of the patella during total knee arthroplasty is reported. Use of the guide prevents tilting of the prosthesis, as well as over or underresection of the patella.     

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。     

人工全膝关节置换术后单纯金属底座髌骨假体的翻修

目的分析带金属底座髌骨假体失败的原因,并观察单纯髌骨假体翻修的临床疗效。方法对 22例 (30膝 )人工全膝关节置换术后因金属底座髌骨假体失败而行单纯髌骨假体翻修者进行回顾性分析。假体均为同一类型的后十字韧带保留型假体,以金属底座髌骨假体置换髌骨。应用膝关节 KSS评分标准评价翻修术后的临床转归。结果髌骨假体失败时间在人工全膝关节置换术后的 26～ 96个月,平均 62.3个月,主要症状有金属摩擦感 (80％ )和膝关节疼痛 (70％ )。术中发现 23膝 (76.7％ )聚乙烯完全磨损、金属底座外露; 9膝髌骨倾斜或半脱位; 2膝完全脱位。 30膝均成功施行骨水泥全聚乙烯髌骨翻修术,随访时间 24～ 81个月,平均 42.5个月。所有患者主诉症状消失,可独立行走活动,膝关节评分从术前的平均 73分（ 27～ 88分）增加至 87分（ 60～ 100分）;膝关节屈曲度由术前的平均 91°增加至 99.5°。结论 (1)金属底座髌骨假体早期失败率较高; (2)髌骨位线不良和异常滑动轨迹是导致带金属底座髌骨假体失败的诱发因素; (3)单纯髌骨假体翻修可获满意的临床结果,其发生并发症的潜在危险和人工全膝关节翻修术相似,应予以重视。     

Anatomic dimensions of the patella measured during total knee arthroplasty

The anatomic measurements of 92 patellae with normal underlying bony structure were studied during total knee arthroplasty before and after resection of the articular surface. The articular surface of the patella was found to have an oval shape with a width-to-height ratio (46 x 36 mm) of 1.30. The dome was 4.8 mm high and displaced medially 3.6 mm. The medial facet was slightly thicker than the lateral facet (18 vs 17 mm). The lateral facet is 25% wider than the medial facet. Coverage provided by oval patellar prostheses was significantly better than with round prostheses. The patellae in women were significantly smaller than in men. Size differences and deformity need to be taken into account when the patella is prepared for resurfacing. It is recommended that the bony resection should be no greater than one third of the maximum patellar thickness to avoid alteration of normal bony structure. Key words: patella, total knee arthroplasty, anatomy.     

Management of severe bone loss in acetabular revision using a trabecular metal shell

We investigated the early results of trabecular metal components in 23 acetabular revisions associated with major bone loss. The mean age was 58.2 years. According to Paprosky's classification, there were 17 type IIIA and 6 type IIIB acetabular defects. Eight chronic pelvic discontinuities were intraoperatively assessed. No additional plating or bone grafting was necessary. The mean postoperative modified Postel-Merle d'Aubigne score was 10.6 points (8-12 points). The mean postoperative position of the center of rotation was 26.3 mm vertically (15-47 mm). The mean inclination was 45.1 degrees (20 degrees-63 degrees). No mechanical failure occurred at a mean follow-up of 35 months (24-50 months). Trabecular metal components appear suitable to achieve primary stability in type III acetabular defect as an alternative to bone graft and cages.