The use of porous metal cones in revision total knee arthroplasty

Massive bone defects represent a major problem in revision total knee arthroplasty. Traditionally, structural allograft has been used for this purpose; however, this is technically demanding and is associated with a failure rate. Metaphyseal tantalum cones have been a major advancement. They have made surgery easier and have yielded better results when compared to reconstruction with allograft. Adding the ability to comfortably use these implants to one’s armamentarium should be a priority for surgeons who regularly revise total knee replacements. These implants have completely replaced the use of structural allografts in the authors’ practice.     

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。     

Porous tantalum cones for large metaphyseal tibial defects in revision total knee arthroplasty: a minimum 2-year follow-up

Sixteen cases of revision total knee arthroplasty requiring the use of porous tantalum tibial cones for 2 T2A, 3 T2B, 4 T3A, and 7 T3B tibial bone defects (Anderson Orthopaedic Research Institute classification) after 13 cases of aseptic loosening and 3 cases of staged reimplantation for infection were reviewed. At an average 31 months (24-38), no patients were lost to follow-up. There were 2 cases of recurrent sepsis requiring removal of a well-fixed cone. In the remaining 14 cases, the reconstructions were functioning well with no reoperations. Radiographs demonstrated reestablishment of the joint line, neutral mechanical axis (average, 5.4° of valgus), and signs of stable osteointegration into the cones. Good short-term results were achieved in complex revisions, with these new reconstructive tools.     

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.     

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。     

全膝关节置换术中胫骨近端骨缺损的处理

目的探讨初次人工全膝关节置换术中胫骨近端骨缺损的植骨方法和疗效。方法2001年10月至2006年3月，在23例（42膝）初次人工全膝关节置换术中采用自体或异体骨移植修复胫骨近端骨缺损，男5例（9膝），女18例（33膝）。骨关节炎19例（35膝），类风湿性关节炎2例（4膝），大骨节病1例（2膝），关节结核1例（1膝）。非包容型骨缺损22例40膝，包容型骨缺损1例2膝。参照Engh ＆ Parks分类法，T1级5膝，T2级33膝，B级4膝。自体髂骨2例3膝，1例2膝为类风湿性关节炎，包容型，为T2级，骨移植起填充作用；另1例1膝为左膝骨关节炎，非包容型，为T3级。异体冷冻骨1例1膝为膝关节结核，同时股骨外髁和胫骨内侧平台骨缺损，为T3级，行大块骨移植，螺钉固定。自体股骨内髁加异体冻于骨移植修复胫骨内侧平台骨缺损1例1膝，为T3级。其余19例37膝均为自体股骨内髁或胫骨外侧平台修整后移植，修复胫骨内侧平台骨缺损，其中螺钉固定14膝。结果术后随访38．2（3-56）个月。所有患者术前均有内或外翻畸形和屈曲挛缩畸形，术后畸形得到矫正，疼痛消失；3个月后均可弃拐行走，生活可以自理。膝关节HSS评分由术前15.3（10-26）分提高到术后86（79-95）分。膝关节活动范围由术前74．4°（0°--90°）提高到术后109．4°80°-135°）。1例于术后3年死于心肺功能衰竭。术后X线复查1年以上者20例（39膝），胫股角为5°-7°，平均6．4°。结论骨移植尤其是自体骨移植在初次人工全膝关节置换术中可以恢复胫骨近端的完整性，为胫骨假体提供初始稳定性，具有简便、实用、经济实惠等优点；可以保留足够的骨量，为以后的翻修提供良好的基础。     

嵌压植骨技术在人工全髋关节翻修术中的应用

目的 探讨使用嵌压植骨技术进行全髋关节翻修术的临床效果。方法1998年12月至2003年9月,采用嵌压植骨技术对48例患者72侧髋关节进行了翻修,平均随访时间25个月,采用Harris评分及X线片观察进行临床疗效评定,并统计并发症的发生率。结果Harris评分从术前平均44．6分提高到术后87．4分,术后优良率为达90．3％;无假体松动及下沉;股骨骨折发生率为4．2％;关节脱位率为1．4％,感染率为1．4％。结论嵌压植骨技术是一种有效重建髋关节置换术后松动所致严重骨缺损的方法。采用冻干异体骨植骨及解剖柄股骨假体同样可以获得满意的临床效果。     

Revision total knee arthroplasty: experience with tantalum cones in severe bone loss

Background

Tantalum-made cones have been developed to compensate for large bone defect involving metaphyseal segment or major portion of the condyle or plateau during knee revision prosthetic surgery.

Materials and methods

We present our experience with femoral and tibial tantalum cones in 11 knees (12 cones overall were used, 6 on femur and 6 on tibia) with 2B or 3 Engh defect type during knee revision arthroplasty. Both cemented and cementless cones were used. Patients were submitted to a specific study protocol in order to exclude a new or persistent infection. Only one intra-operative complication not related to the implantation of the trabecular metal cone was observed.

Results

Neither early nor late post-operative re-infection was reported in our series at a mean follow-up of 39.8 months. Radiological analysis showed no cases of aseptic loosening or migration of the components. The only post-operative complication was delayed union of the tibial tuberosity in a patient who required osteotomy for surgical exposure. All patients improved both clinically and functionally.

Conclusions

The results of this study support the use of femoral and tibial porous tantalum metaphyseal cones as a viable option for revision knee arthroplasty with large amount of bone defects in both tibia and femur. We think that the main advantages of tantalum cones compared to structural bone graft lie in faster full weight-bearing recovery and in the cones' potential long-term maintenance of mechanical support. By our results, we can eventually exclude any concern regarding a possible direct correlation of the trabecular metal cones with re-infection.     

Histologic retrieval analysis of a porous tantalum metal implant in an infected primary total knee arthroplasty

Porous tantalum (Zimmer, Inc, Warsaw, Ind) has the theoretical advantage of improved biologic fixation because of its high porosity, interconnected pore space, and modulus of elasticity. We present a case report documenting the retrieval and bone ingrowth analysis of a porous tantalum tibial component in an infected total knee arthroplasty. Results demonstrated a significantly larger amount of bone ingrowth present in the tibial posts (36.7%) when compared with the bone ingrowth into the tibial baseplate (4.9%) (P < .001). The data suggest that bone ingrowth seen in the plugs as well as baseplate was suggestive of viable bone tissue with healthy bone marrow, osteocytes, and lamella, resulting in a well-fixed tibial implant even at revision surgery for an infected total knee arthroplasty.     

Morselized bone grafting of defects in revision total knee arthroplasty.

In a prospective, multicenter study evaluating one revision knee system, 33 of 409 patients underwent morselized bone grafting for tibial and femoral defects. Fifty-four percent of defects were bicondylar and the defect volumes averaged 36 cc3. There was no difference in preoperative or postoperative knee scores between patients undergoing morselized grafting and the entire group. Radiographic evaluation showed remodeling of the grafted areas consistent with viable incorporation of the graft. The incidence of radiolucent lines, at 2 years followup, was not different between the patients who received grafting and the patients who did not receive grafting. There have been no clinical failures or reoperations in the patients who received morselized bone grafting. Morselized bone grafting seems to offer a viable alternative in the reconstruction of osseous defects in patients undergoing revision total knee arthroplasty.     

Cancellous impaction bone grafting of acetabular defects in complex primary and revision total hip arthroplasty

The reconstruction of major acetabular bone defects during revision, conversion, and primary total hip arthroplasties (THAs) is challenging. We reviewed a consecutive series of 168 THAs (108 revisions, 8 conversions, and 52 primary THAs) performed by 1 surgeon (S.B.G.) between 1997 and 2008 using impaction bone grafting for acetabular reconstruction. Autograft, cancellous allograft croutons, and demineralized bone matrix were used to fill bone defects as needed. The acetabular bone deficiency was classified according to the American Academy of Orthopaedic Surgeons: type I, segmental deficiency with significant rim defect; type II, cavitary defects medially or posteriorly; type III, combined cavitary and segmental deficiency; type IV, pelvic discontinuity; and type V, arthrodesis. According to this method, 56 hips had type I, 31 hips had type II, 48 hips had type III, and 27 hips had type IV deficiencies. Of the 168 patients, 19 subsequently died of causes unrelated to the THA, and 11 were lost to follow-up. All patients had at least 2 years of follow-up. Average Harris Hip Score improved from 45.5±17.9 preoperatively to 81.1±16.5 postoperatively (P<.05) for revision THAs, from 40.0±11.3 preoperatively to 85.0±12.8 postoperatively (P<.05) for conversion THAs, and from 42.3±14.9 preoperatively to 85.0±12.0 postoperatively (P<.05) for primary THAs. All impaction grafted bone (allograft, autograft, or a combination) incorporated radiographically, thus restoring bone stock. Complications included 1 early infection, which was managed successfully with debridement and liner exchange, and 2 late infections that were managed successfully with staged revision. Two revisions required subsequent re-revision for late loosening. Two hip dislocations occurred, 1 of which required surgical treatment to place a constrained liner.     

Bone grafting of tibial defects in primary and revision total knee arthroplasty

Bone grafting of tibial defects in primary and revision total knee arthroplasty is performed by at least two different methods, preferably with local autogeneic bone. Incorporation of the graft occurs between four and eight months. No restriction in weight-bearing is recommended, except with repair of large defects. Bone grafting is a viable alternative to using custom tibial prostheses or excess cement, even for very large defects.     

Femoral bone grafting in primary and revision total knee arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results of TKA's with morsellized and solid femoral bone grafting. From April 1989 to February 1996, 6 primary and 18 revision TKA's with femoral bone grafting were performed in 22 patients with an average age of 62 years. Eleven knees were affected by rheumatoid arthritis, 10 by osteoarthritis, 2 by osteonecrosis and one by hemophiliac arthropathy. The femoral bone defects were large in 12, medium in 9, small in 3, contained in 10 and uncontained in 14 cases. Reconstruction was done with impacted morsellized fresh frozen trabecular bone grafts in 13 knees, with solid bone grafts in 7 knees and with combined grafts in 4 knees. Twenty-one cases were clinically evaluated at an average of 38 months (range: 9-89 months). The average Knee Society knee score increased by 39 points to 85 points at follow-up. The average functional score increased by 22 points to 48 points. Two cases with solid femoral bone grafts failed due to aseptic loosening. There were no infections. Radiographic follow-up revealed osteopenia around the femoral component in 10 knees. Two knees showed circumferential radiolucency around the femoral stem, and 5 knees had minor radiolucency at the anterior part of the femoral component. Radiographic incorporation was present in 5 of the 6 cases that could be evaluated. Histologic analysis of two biopsies revealed incorporation of the morsellized bone graft. The authors advocate impacted morsellized bone grafting for contained and small-to-medium uncontained femoral bone defects in combination with cemented TKA.     

Simultaneous revision and contralateral primary total knee arthroplasty

BACKGROUND: There is controversy regarding whether simultaneous or staged bilateral total knee arthroplasty should be performed in patients with bilateral gonarthrosis. In addition, revision total knee arthroplasties have been less successful than primary arthroplasties. The purpose of this study was to evaluate the results of simultaneous revision and contralateral primary total knee arthroplasties performed during the same setting. METHODS: The study cohort included 150 knees in seventy-five patients who had undergone revision arthroplasty because of aseptic failure of a total knee arthroplasty and a contralateral primary arthroplasty for severe gonarthrosis under the same anesthetic. The study group was compared with a control group of sixty patients who had severe arthritis in one knee and had undergone unilateral revision total knee arthroplasty on the contralateral side. The duration of follow-up averaged five years in the group treated with the simultaneous arthroplasties and eight years in the control group. Clinical and radiographic results were evaluated with the Knee Society rating system. RESULTS: In the study group, the average knee score improved by 48 points on the side of the primary arthroplasty and by 37 points on the side of the revision. At the last follow-up visit, most (sixty-five) of the seventy-five patients stated that the knee with the revision felt better than the knee with the simultaneously performed primary arthroplasty. In the control group, the average knee score improved by 30 points on the side of the revision arthroplasty. However, forty-five of the sixty patients had a primary total knee arthroplasty on the contralateral side within two years after the index revision arthroplasty; by four years, all sixty patients had undergone a contralateral primary arthroplasty. CONCLUSIONS: We found a favorable outcome in patients who had undergone simultaneous revision and contralateral primary total knee arthroplasties. Despite a lower mean knee score and less motion, most patients seemed to prefer the knee with the revision arthroplasty to the knee with the primary procedure. These results suggest that this combined procedure is a safe and favorable alternative to a staged procedure consisting of revision and subsequent contralateral primary total knee arthroplasty.     

Bone mineral density changes of the proximal tibia after revision total knee arthroplasty. A randomised study with the use of porous tantalum metaphyseal cones

Purpose

Forty patients were enrolled in a prospective randomised study using conventional method or “Trabecular Metal Cone” (TM Cone) (Zimmer inc., Warsaw, USA) for reconstruction of bone loss of the proximal tibia during revision total knee arthroplasty (rTKA). The aim was to evaluate changes in bone mineral density (BMD) at the proximal tibia.

Material and methods

Thirty-six patients [median 67 years (range: 40–85 years)] received rTKA with NexGen® (Zimmer Warsaw, USA) revision system. Knee Society´s Knee Scoring System and the Anderson Orthopaedic Research Institute (AORI) bone classification was used. Changes in BMD were measured by dual energy X-ray absorptiometry (DEXA).

Results

Knee and function score improved in both groups. No significant changes between the groups were found. Changes in BMD within the two groups were quite similar. Overall decreases in BMD of 0.1 - 5.4 % were found in both groups (ROI 1–6) postoperative to 12 months of follow-up, except that ROI 7 showed an increase in BMD (0.8 - 1.3 %). After 24 months of follow-up, an increase in BMD was found along the stem (ROI 2–5) of 1.9 - 6.3 % , with significant changes in the TM Cone Group (ROI 3, 4, 5) . No significant changes in BMD between the groups were found.

Conclusions

The bone remodelling pattern was almost the same in the two groups after two years.