Treatment of an intraoperative patellar fracture during revision total knee arthroplasty

An intraoperative vertical patellar fracture occurred through a central osteolytic defect during removal of a metal-backed patellar component. The fracture was treated successfully with cerclage wire fixation and implantation of a cemented patellar component.     

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.     

Modular porous metal augments for treatment of severe acetabular bone loss during revision hip arthroplasty

Modular acetabular augments were implanted in 16 patients (16 hips) for support of an uncemented hemispheric acetabular component during revision acetabular reconstruction. Based on the classification of Paprosky, acetabular bone defects were classified as 2A in one hip, 2B in three hips, 2C in one hip, 3A in five hips, and 3B in six hips. Preoperatively, the prosthetic femoral head centers were located at a mean horizontal distance of 18.6 mm (range, -3-46 mm), and a mean vertical distance of 27.6 mm (range, -16-52 mm) from the approximate femoral head center. Postoperatively, the prosthetic femoral head centers were located at a mean horizontal distance of 10.4 mm (range, 1-25 mm), and a mean vertical distance of 7.4 mm (range, -15-25 mm). At final followup, no implant had evidence of migration or loosening. At early clinical followup, this modular acetabular augment system seems helpful in acetabular reconstructions that cannot be treated with an uncemented hemispheric cup that would have required other forms of treatment such as structural allografts, acetabular cages, bilobed acetabular components, or custom acetabular components. Longer term followup is required to determine whether there are untoward effects of using a modular acetabular reconstructive system.     

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.     

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)     

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.     

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。     

Joint line and patellar height restoration after revision total knee arthroplasty

Background:

Restoration of proper joint line (JL) position and patellar height in revision total knee arthroplasty (TKA) is essential in the recovery of knee function and kinematics. We determined whether the JL position and patellar height could be restored in patients undergoing septic and aseptic revision TKA.

Materials and Methods:

We retrospectively reviewed 70 patients (74 knees) who had revision TKA between September 2004 and December 2010. Forty seven knees had a two stage revision for infected TKA and 27 knees for aseptic failure. The JL position, patellar height and patellar tendon (PT) length were measured and compared between primary TKA and post revision. The clinical scores including a hospital for special surgery (HSS), Knee Society Score (KSS), Western Ontario and McMaster Universities (WOMAC) and range of motion (ROM) were compared.

Results:

The overall JL increased from 17.51 mm to 18.37 mm post revision, the Insall-Salvati (IS) ratio declined from 0.98 to 0.92, and the PT length declined from 42.92 mm to 39.45 mm. 9 of the 21 patellar baja knees improved to normal patellar height. After revision, the JL in the septic group (17.02 mm) was significantly lower than the aseptic group (20.74 mm). The changes of the JL position and IS ratio in the septic group were significantly larger than the aseptic groups (P < 0.05). JL position had a positive correlation to the IS ratio and PT length post revision. The knee function scores including HSS, KSS, WOMAC scores, and ROM all improved post revision compared to pre revision (P < 0.05), and the septic group had a lower knee function compared to the aseptic group. JL position and IS ratio post revision had no correlation to the HSS, KSS, WOMAC scores, and ROM.

Conclusions:

JL position can be sufficiently restored with appropriate distal femoral augment reconstruction after revision TKA, but the patellar height cannot be well improved, especially in the septic revision with obvious PT contracture. No correlation was found between the JL position and patellar height to the knee function post revision TKA.     

可活动关节间隔垫技术治疗严重全膝关节置换术后感染

目的 探讨运用可活动关节间隔垫技术治疗有内科基础病及局部窦道形成的严重全膝关节置换术后感染的疗效和安全性.方法 2002年1月至2008年3月,10例全膝关节置换术后延迟感染患者,男3例,女7例;年龄23～73岁,中位年龄67岁.患者均采用二期再置换手术治疗:第一期手术,取出假体、彻底清创,并植入含抗生素的可活动间隔垫,切除窦道,封闭原窦道口.术后予以积极抗感染和功能康复治疗.待感染控制后行第二期手术,取出可活动间隔垫,植入新的关节假体.采用美国特种外科医院(the hospital for special surgery,HSS)膝关节评分以及膝关节活动度评价治疗效果.结果 1例患者治疗期间血糖控制不佳,一期手术后感染未得到控制而行关节融合术,另外9例患者感染均获治愈.随访时间24～90个月,平均50个月.随访期内无一例发生感染复发及并发症,患者无膝周肿痛等不适主诉.术前患膝HSS评分32～63分,平均48分;二期手术前HSS评分62～91分,平均79分;末次随访时HSS评分74～95分,平均89分.术前、二期术前以及二期术后患膝关节功能的优良率分别为0、80%和100%.术前膝关节活动度为13°～70°,一期术后膝关节活动度为8°～93°,末次随访时膝关节活动度为3°～110°.结论 可活动关节间隔垫技术是治疗全膝关节置换术后严重感染的一种安全、有效的方法,可在控制感染的基础上尽可能保留关节功能.

Abstract：

Objective To investigate the efficiency and safety of articulating spacer for severe infected knee arthroplasty in patients with medical comorbidities and local sinus tracts. Methods Ten consecutive patients with medical comorbidities (rheumatoid arthritis, diabetes mellitus, etc) or local sinus tracts,who were complicated with late infected TKA, were included in the study. All the patients underwent twostage revision using articulating spacers. All of the patients were debridement thoroughly and followed by implantation of an antibiotic-loaded cement articulated spacer. Two-stage revisions were not followed untill the infection were controlled. The hospital for special surgery (HSS) knee scoring system and range of motion were used to evaluate the outcomes. Results One patient underwent knee fusion because the infection was not controlled after first-stage surgery. The other 9 patients had no evidence of infection. The mean follow-up was 50 months (range, 24-90 months), no recurrent infection developed for these 9 patients. The mean modified HSS score had improved from 48 points (range, 32-63) before the resection surgery to 79 points (range,62-91) at the end of the spacer period. At the latest follow-up, the modified HSS score averaged 89 points (range, 74-95). The good and excellent rate was 0, 80% and 100%, respectively. The average range of motion had increased from 13°-70° preoperatively to 8°-93° prior to the revision. And at the latest follow-up, the range of motion averaged 3° to 110°. Conclusion The delayed two-stage revision using an articulating spacer is effective in the treatment of chronically infected TKA characterized by simple, good reproducible, high rate of infection control, better joint function after surgeries     

Management of severe periacetabular bone loss combined with pelvic discontinuity in revision hip arthroplasty

Purpose

Revision of failed total hip arthroplasty with massive acetabular bone loss resulting in pelvic discontinuity represents a rare but challenging problem. The objective of this study was to present short to mid-term results of revision total hip arthroplasty with a custom-made acetabular implant in a consecutive series of patients with pelvic discontinuity.

Methods

We retrospectively reviewed 18 consecutive patients with massive acetabular bone loss (Paprosky Type 3B) resulting in pelvic discontinuity reconstructed with revision total hip arthroplasty using a custom-made acetabular component. The prosthesis was created on the basis of a thin-cut 1-mm computed tomography (CT) scan of the pelvis. Initial stability of the implant was obtained by screw fixation. Harris hip score and sequential radiographs were used to evaluate the clinical and radiographic results.

Results

At an average follow up of 30 months (range 17–62 months) 16 of 18 (88.9 %) custom-made implants were considered radiographically stable without signs of acetabular migration of more than 2 mm in the horizontal or vertical direction, implant rotation or screw breakage. Complications included two periprosthetic joint infections treated with explantation of the implant. Three patients had recurrent dislocations postoperatively. The mean Harris hip score improved from 28?±?12 points preoperatively to 69?±?13 points at the time of last follow up.

Conclusion

Treatment of acetabular bone loss and pelvic discontinuity with a custom-made acetabular component can provide a durable solution with good clinical and radiographic results.     

Extensively porous-coated femoral revision for severe femoral bone loss

Of 275 femoral revisions done at our institution from 1982 to 1986, we identified 34 patients (35 hips) who represented the senior author's (C.A.E., Sr.) most difficult revision cases as a result of extensive femoral bone loss at least 10 cm below the lesser trochanter. The patients were revised with fully porous-coated femoral components ≥190 mm. We evaluated 25 of the patients (26 hips) who had a minimum 10-year follow-up (mean, 13.3 years). Survivorship was 89% at 10 years with femoral revision as the endpoint (Kaplan-Meier). The femoral aseptic loosening rate was 15% (4 of 26). Three stems were loose but did not warrant reoperation. One stem was revised for aseptic loosening, 1 was revised for septic loosening, and 1 was revised for a fractured femoral component. Bypassing weak or absent femoral bone with an extensively porous-coated stem is an effective reconstructive technique for patients with extensive femoral bone loss.     

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。