Rekonstruktion der Strecksehneninsertion im Rahmen des Knieprothesenwechsels und der Tumorendoprothetik

Reconstruction of the extensor mechanism in extended revision after total knee replacement and tumor surgery remains a clinically relevant problem. Due to large tibial bone defects with resection of the extensor insertion area, the specific problem of patella ligament refixation frequently arises. Several biological approaches and augmentation techniques have been published. Most of these are associated with a high rate of revision surgery because of failed replacement of the extensor mechanism and unsatisfactory functional outcome. Surgical reconstruction of these tendon defects is complicated by the difficulty of completely neutralizing tensional force across the repair. To overcome this problem, methods have been developed to reinforce the reconstruction with overlapping flaps; in addition, artificial materials are being increasingly used for tension neutralization. These artificial strips need special fixation mechanisms on the tibial component and specific technical modifications of the prosthesis.The present study gives an overview of reconstruction modalities of the extensor mechanism and provides an improved technology for better reconstruction by using artificial strips combined with specific modifications of the tibial component.     

Problems and solutions of the extensor mechanism

Problems related to the extensor mechanism can be devastating and severely compromise the end result of revision knee replacement surgery. Many of these complications can be prevented by careful surgical technique, especially intraoperative avulsion of the patellar tendon. Fractures of the patella in the most extreme forms can lead to prosthetic loosening and disruption of the extensor mechanism. In the most severe cases, complete absence of the extensor mechanism may require allograft extensor mechanisms to restore extensor function. Alterations in rehabilitation and postoperative treatment are often necessary to ensure an excellent result. Along with restoration of bone defects, achieving excellent knee alignment and stability, a functional and aligned extensor mechanism is key to an excellent result in knee revision surgery.     

Is There a Place for Rotating-Hinge Arthroplasty in Knee Revision Surgery for Aseptic Loosening?

We reviewed the results of 78 revision total knee arthroplasties using a rotating-hinge device, performed from 1993 through 2002. The average follow-up was 7.83 years. Only patients requiring revision arthroplasty due to aseptic loosening were included. Reasons for revision were malalignment with or without polyethylene wear (47), instability (24), extensor mechanism failure (3), and periprosthetic fracture (4). The mean preoperative scores according to the American Knee Society rating scale was 37.5 points for knee score and 32.8 points for function score. Postoperatively, the knee score improved to 85.7 points and the function score improved to 61.4 points. Nineteen patients had complications related to the design prostheses (mostly minor complications). Fifty-seven patients (73%) had excellent results, with a range of motion of 104 degrees in flexion and complete extension. For extreme circumstances, such as gross instability of the medial collateral ligament, massive bone loss, comminuted fracture, and chronic dysfunction of the extensor mechanism, there is a place for hinged revision implant surgery with good clinical results and quality of life.     

Stellenwert der Revisions- und Tumorendoprothetik bei der Versorgung periprothetischer Frakturen der unteren Extremität

Periprosthetic fractures of hip and knee prostheses are gaining clinical significance due to the increasing numbers of of primary arthroplasties. Additionally, these fractures are often associated with poor bone quality or present in patients after multiple revision procedures and concomitant excessive bone defects precluding those patients to be adequately treated by conventional osteosynthesis. Revision implants provide a wide range of options for the treatment of these fractures in order to achieve good clinical results. In the acetabular region cavitary defects associated with periprosthetic fractures can be treated by the use of megacups. Extensive segmental defects and pelvic discontinuity necessitate the use of cups with additional iliac support or even customized implants. Proximal femoral fractures can usually be fixed with modular stems and diaphyseal anchorage. Periprosthetic knee joint fractures can be treated with revision implants with modular sleeves or augment-combinations allowing sufficient bridging of bony defects. Functional reconstruction or refixation of the extensor mechanism is of crucial importance.     

Rotating hinge total knee arthroplasty in severly affected knees

A consecutive series of 24 knees in 21 patients who received a Finn rotating hinge for primary (nine knees) or revision (15 knees) total knee arthroplasty between August 1993 and January 1997 was reviewed. The average followup was 33 months (range, 21-62 months) for all patients in the study. Seventeen patients (20 knees) were followed up for more than 2 years. Twenty-four knees (21 patients) were categorized according to Knee Society scoring criteria: 37.5% (nine knees) were Category A, 25% (six knees) were Category B, and 37.5% (nine knees) were Category C. Using the Knee Society knee and function scores, clinical and radiographic results were assessed and outcome analysis was determined. The average Knee Society knee score improved from 44 points (range, 5-64 points) before surgery to 83 points (range, 45-95 points) after surgery; the average functional score according to the Knee Society system improved from 10 points (range, 0-35 points) before surgery to 45 points (range, 0-100 points) after surgery. Pain and function markedly improved after surgery. For treatment of the most severely affected knees with compromised bone and ligamentous instability, the Finn total knee replacement appears to be an acceptable option. As a rotating hinge design, the prosthesis at early followup provides excellent pain relief, restoration of walking capacity, and stabilization, without evidence of early mechanical failure.     

骨肿瘤初次保肢手术后生物性重建失败的肿瘤假体翻修术

目的评估骨肿瘤初次保肢手术后生物性重建失败的肿瘤假体翻修的疗效。方法2004至2006年，13例骨肉瘤和3例骨巨细胞瘤患者在香港威尔斯亲王医院接受手术治疗。15例患者应用同种异体骨重建，另1例患者应用带血管腓骨移植重建骨缺损。应用肿瘤型假体进行翻修手术的重建。翻修术后患者膝关节活动范围良好时，订制的可延长假体接受延长手术。结果患者平均年龄23．2岁（13～43岁），平均随诊26．4个月（6～47个月）。翻修手术的原因包括：7例患者出现同种异体骨骨折或软骨下骨塌陷，5例患者骨不愈合，3例患者异体骨感染，1例患者膝关节僵硬。翻修手术的假体包括10例患者应用订制型假体，其他患者应用组合式假体。翻修手术的部位包括9例股骨远端假体，6例胫骨近端假体和1例股骨中段假体。订制假体中6例是可延长假体，假体的延长方式中5例是微创延长、1例无创延长。翻修手术后，膝关节活动改善，平均从18．1°（0°-90°）至91．9°（50°-120°）。下肢缩短不等长畸形从平均5cm（2-11．5cm）纠正至平均1．5cm（0-4cm）。翻修术后患肢功能MSTS评分从34．6％改善到89．2％。翻修术后2例患者出现部分皮肤坏死，1例患者出现腓总神经麻痹，以后部分恢复，1例患者出现胫骨裂纹骨折；没有感染和植入物失败。结论保肢手术后生物学重建失败所引起下肢缩短和僵硬，应用人工假体翻修是可行的，早期效果令人鼓舞。膝关节僵硬患者可获得良好的关节活动度。严重的下肢缩短畸形通过可伸长假体逐渐获得纠正。     

Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents

BACKGROUND: The management of anterior cruciate ligament injuries in skeletally immature patients is controversial. Conventional adult reconstruction techniques risk potential iatrogenic growth disturbance due to physeal damage. The purpose of this study was to evaluate the results of a physeal sparing, combined intra-articular and extra-articular reconstruction technique in prepubescent skeletally immature children. METHODS: Between 1980 and 2002, forty-four skeletally immature prepubescent children and adolescents who were in Tanner stage 1 or 2 (with a mean chronological age of 10.3 years) underwent physeal sparing, combined intraarticular and extra-articular reconstruction of the anterior cruciate ligament with use of an autogenous iliotibial band graft. Twenty-seven patients had additional meniscal surgery. Functional outcome, graft survival, radiographic outcome, and growth disturbance were evaluated at a mean of 5.3 years after surgery. RESULTS: Two patients underwent a revision reconstruction for graft failure at 4.7 and 8.3 years postoperatively. In the remaining forty-two patients, the mean International Knee Documentation subjective knee score (and standard deviation) was 96.7 +/- 6.0 points, and the mean Lysholm knee score was 95.7 +/- 6.7 points. The results of the Lachman examination for anterior cruciate ligament integrity was normal for twenty-three patients, nearly normal for eighteen patients, and abnormal for one patient. The results of the pivot-shift examination were normal for thirty-one patients and nearly normal for eleven patients. Four of the twenty-three patients who underwent concurrent meniscal repair had a repeat arthroscopic meniscal repair or partial meniscectomy. The mean growth in total height from the time of surgery to the final follow-up evaluation was 21.5 cm. No patient had an angular deformity measured radiographically or a discrepancy in the length of the lower extremities measured clinically. CONCLUSIONS: Physeal sparing, combined intra-articular and extra-articular reconstruction of the anterior cruciate ligament with use of an autogenous iliotibial band graft in skeletally immature prepubescent children and adolescents provides excellent functional outcome with a low revision rate and a minimal risk of growth disturbance.     

Tibial tubercle osteotomy in total knee arthroplasty surgery

Tibial tubercle osteotomy (TTO) is a recognized technique for improving exposure when performing total knee arthroplasty surgery. Forty-two patients were reviewed at a mean of 8 years after TTO. Preoperatively, mean extension was 8 degrees +/- 14 degrees , mean flexion 74 degrees +/- 30 degrees , and Knee Society score 73 +/- 37. At latest follow-up, mean extension was 4 degrees +/- 15 degrees , mean flexion 91 degrees +/- 22 degrees , and Knee Society score 124 +/- 42.6 (P < or = .0001). Seventy-three percent of patients had an excellent/good score at latest follow-up. Twenty-five percent of patients experienced no extensor lag, and 66% of extensor lags had resolved within 6 months. Mean time for osteotomy union was 14 weeks. In this series, TTO performed to enhance surgical exposure did not adversely affect the outcome after total knee arthroplasty but resulted in serious complications in 5% of patients.     

Joint line restoration after revision total knee arthroplasty.

In 99 patients, 107 knee replacements were revised in two centers by two surgeons using a single revision total knee arthroplasty system. A retrospective radiographic review of joint line position before and after revision total knee arthroplasty was made, and compared with the joint line position before primary knee arthroplasty. Prospectively collected Knee Society Clinical Rating Scores were correlated with radiographic findings. The joint line position in unreplaced knee replacements averaged 16 mm, and the joint line position in knee replacements before revision surgery averaged 17 mm. The joint line was elevated by the revision total knee arthroplasty in 85 of 107 knees (79%). After the revision total knee replacement, the joint line elevation averaged 24 mm. The Knee Society Clinical Rating Score after revision surgery averaged 131 points. If the joint line position was elevated more than 8 mm, the Knee Society Clinical Rating Score averaged 125 points, if the joint line was elevated less than 8 mm, the score averaged 141 points. Joint line elevation after revision total knee replacement is a problem. Excessive elevation may result in worse clinical outcomes. Distal femoral augments should be used more often and with greater thicknesses. Standard implants used for revision surgery should have increased distal dimensions.     

Proximaler Femurersatz mit dem MUTARS®-System

In the proximal femur a modular tumor prosthesis can be used today for reconstruction after resection of primary malignant bone tumors, metastatic lesions, and in revision surgery. The MUTARS® Münster system offers a high modularity and the possibility of combining it with the hip and knee revision system. Technical innovations, like hexagonal press fit bone anchorage, fine adjustment of rotation, silver coating of the surface of the prosthesis, and functional reconstruction with the help of a Trevira tube, guarantee a very good long-term survival of the prostheses and protection against the main complications such as aseptic loosening, deep infection, and instability.     

Management of extensor mechanism deficit as a consequence of patellar tendon loss in total knee arthroplasty: a new surgical technique

Extensor mechanism disruption is an uncommon but devastating complication of total knee arthroplasty. A new technique of extensor mechanism reconstruction for patellar tendon loss, after total knee arthroplasty, with the help of extensor mechanism composite allograft is described. Four patients with chronic extensor mechanism-deficient total knee arthroplasty were undertaken for revision surgery along with reconstruction of extensor mechanism with an innovative technique using an extensor mechanism composite allograft consisting of a patella-patellar tendon-tibial tubercle. On final follow-up, none of the patients had extensor lag but for 10 degrees of extensor lag in 1 patient only. Providing an environment for bone-to-bone healing both proximally as well as distally and supervised postoperative rehabilitation led to encouraging results in the management of a failed extensor mechanism after total knee arthroplasty.     

结构性植骨修复膝关节翻修术中严重骨缺损的临床效果及相关分析

目的探讨同种异体结构性植骨在膝关节翻修术中大块骨缺损中应用的临床效果和意义。方法1994～2001年芬兰坦佩雷大学医院应用单一翻修假体及同种异体骨结构性植骨治疗膝关节置换术大块骨缺损患者10例（膝）,男1例,女9例,平均年龄70岁（61—77岁）,平均随访5年（1～8年）,所有手术均由两名高年资专科医师执行,采取KSS评分评估术前术后膝关节功能。结果最后随访时,患者膝关节KSS评分由术前的平均39分（4～51分）提高至81分（28—102分;P〈0．05）;疼痛评分由术前的18分（0—30分）提高至42分（10—50分;P〈0．05）。2例出现假体周围透亮线（〈1mm）,但没有任何松动症状;所有结构性植骨均获得满意的愈合,最后随访时没有出现吸收征象,1例患者术后出现膝前疼痛,经髌骨表面置换后症状消失。结论同种异体骨结构性植骨应用在膝关节翻修术中大块骨缺损中可取得满意的临床效果,重建下肢力线、第三代骨水泥技术的应用及有由专科医师实施手术是获得良好临床效果的保证。     

Reconstruction of a ruptured patellar tendon with achilles tendon allograft following total knee arthroplasty

BACKGROUND: Rupture of the patellar tendon after total knee arthroplasty is a rare and debilitating complication. Proper surgical management of this condition remains controversial. The purpose of this study was to review the results of reconstruction of a ruptured patellar tendon with an Achilles tendon allograft following total knee arthroplasty. METHODS: We reviewed our experience with the use of a fresh-frozen Achilles tendon allograft with an attached calcaneal bone graft to restore extensor function in nine patients with patellar tendon rupture following total knee arthroplasty (five primary and four revision). All patients were examined clinically and radiographically at an average of twenty-eight months. RESULTS: The average knee and functional scores improved from 26 and 14 points, respectively, before the surgery to 81 and 53 points after the surgery. The average extensor lag decreased from 44 degrees preoperatively to 3 degrees postoperatively, and the average range of motion of the knee increased from 88 degrees to 107 degrees. Two grafts failed in the early postoperative period. Both were repaired successfully. Radiographs showed an average proximal patellar migration of 17.8 mm, which did not appear to affect extensor function. CONCLUSIONS: This short-term follow-up study showed that once an Achilles allograft has healed, it can serve as a reliable reconstruction of a ruptured patellar tendon following total knee arthroplasty. This technique may be particularly suited for patients in whom the extensor mechanism was compromised by multiple prior operations. Continued follow-up is necessary to determine the long-term durability of these results.     

Medial Gastrocnemius Flap for Reconstruction of the Extensor Mechanism of the Knee Following High-Energy Trauma. A minimum 5 year follow-up

IntroductionThe purpose of this study was to assess the medium-term results of reconstruction of the extensor mechanism using the medial gastrocnemius while also providing soft tissue coverage.Materials and methodsThis retrospective review consisted of a consecutive series of four patients (age 28–40 years) with complex high energy traumatic injuries to lower extremity including both soft tissue loss and disruption of the knee extensor mechanism. The medial gastrocnemius rotational flap was used to reconstruct the patellar tendon and restore soft tissue coverage simultaneously. Range of motion and extensor lag; functional recovery was judged by return to work and sports activity. Validated measures included the Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score, and the modified Cincinnati Score.ResultsAt the final follow up was 61.5 (57–66) months after reconstruction, the mean SF 12 physical component score ranged from 21.7 to 56.8 with a median of 55.3; the mental component from 42.8 to 60.7 with a median of 58.6. The KSS knee score ranged from 50 to 78 with a median of 68; the function score from 65 to 90 with a median of 85. The Oxford knee score ranged from 22 to 45 with a median of 33.5. The KOOS ranged from 28 to 82.7 with a median of 73.7 and the modified Cincinnati score from 38 to 82 with a median of 76.5. Knee range of motion ranged from 0 to 120°. Of the four patients three returned to working fulltime in their profession and returned to sports, including mountain biking and fitness training.ConclusionsFor severe traumatic knee injuries with the combination of soft tissue defects and disruption of the extensor mechanism, the medial gastrocnemius flap provides an excellent reconstructive option to address both problems simultaneously. The results of this small case series support the use of this limb salvage technique.     

Extensor mechanism allografts in total knee arthroplasty.

Forty knees in 40 patients who had a chronic extensor mechanism disruption after knee arthroplasty underwent extensor mechanism allograft placement to restore extensor function. Thirteen knees were infected previously and 11 knees did not respond to previous attempts at direct extensor repair or reconstruction. Two patients died and two patients underwent above the knee amputation because of recurrent infection. The final group of 36 patients was studied for a mean followup of 3.6 years (range, 2-10 years). Clinical evaluations were performed using a modified Knee Society scoring system. The average range of motion in the entire group of patients was 1.4 degrees extension to 98 degrees flexion. The average extensor lag was 13 degrees in 15 of 36 patients. There were eight extensor allograft ruptures, which were treated by repeat extensor allograft placement. The average knee scores for function improved from 37 points preoperatively to 68 points postoperatively. Despite these initial ruptures, 34 of 36 patients had a successful clinical result. These results support the use of this technique for complete extensor mechanism loss after knee arthroplasty when direct repair is unfavorable.     

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.     

Ten- to 14-year clinical followup of the cementless Natural Knee system.

Of 300 consecutive knees (238 patients) that had undergone arthroplasty with the cementless Natural Knee prosthesis from 1985 to 1989, 176 knees (141 patients) were available for followup at an average of 12 +/- 1 years after the operation. Knee function was improved significantly. Modified Hospital for Special Surgery knee scores improved from 59.1 +/- 13.2 points preoperatively to 97.8 +/- 4.7 points at last followup. At last followup, knee range of motion averaged 0 degrees +/- 2 degrees to 120 degrees +/- 10 degrees. Implant survival was 93.4% (including infection and simple polyethylene exchanges) and 95.1% (excluding infection and simple polyethylene exchanges) at 10 years when applying the Kaplan-Meier survival analysis, using loose components, revision, or both as failure criteria. Besides the three revisions for infection, only two femoral and one tibial component required revision. The patellar component survivorship at 10 years was 95.1%. All patellar revisions were attributed to edge wear. Subsequent operative and design changes, including patellar component medialization and countersinking, have decreased the incidence of patellar revision. The long-term results of this cementless knee system compare favorably with those of cemented systems. The Natural Knee design has provided excellent and predictable long-term clinical results in the current series of active patients.     

Quality of life after knee revision arthroplasty

BACKGROUND AND PURPOSE: Radiographic and clinical survival analyses of revision total knee replacement (TKR) are considered acceptable outcome measures. However, the full influence of revision knee replacement on the overall health status of patients remains poorly defined. METHODS: We prospectively studied the health-related quality of life outcome in 94 patients who underwent revision knee replacement surgery over a 5-year period. Comparisons were drawn between the Nottingham health profile (NHP) scores and the Knee Society score pre-revision, and those obtained at 3 months, 1 year and 5 years after revision knee arthroplasty. RESULTS: We found a significant improvement in Knee Society score and NHP pain scores 3 and 12 months after revision TKR (p < 0.05). No other modalities of the NHP showed a significant change. 5 years after surgery, pain was less than before revision (p = 0.2), but energy level was considered worse (p = 0.07). Knee Society scores were found to be higher pre- and postoperatively for patients undergoing revision for reasons other than sepsis than for patients with sepsis. Patients requiring implantation of a hinged prosthesis also had lower Knee Society scores than those patients receiving a non-hinged implant. Repeated revision was associated with a downward trend in Knee Society score with each surgical intervention.     

Revision total knee arthroplasty: fixation with modular stems

The number of revision total knee replacements continues to increase annually. To date, much of the literature has focused on the performance of titanium revision systems. The primary aim of the current study was to review the mid term results of a contemporary revision knee system, with alternative design features. Ninety-one consecutive patients having aseptic revision total knee arthroplasty with one, modular all-cobalt chrome stemmed revision knee system using hybrid stem fixation were studied prospectively. Eighty-nine revisions in 84 patients were reviewed at a mean of 5.9 years (range, 4.1-8.6 years). Significant improvements in pain scores (15 +/- 14 to 38 +/- 14), function (40 +/- 24 to 53 +/- 29), range of motion (88 degrees +/- 23 degrees to 98 degrees +/- 18 degrees ), and total Knee Society score (85 +/- 40 to 132 +/- 40) were seen at followup. Five patients had revision surgery, with a Kaplan-Meier survivorship of 93.5% at 8.6 years. Intermediate results support the use of cobalt chrome components and hybrid cement fixation; however, this fixation in combination with high articular constraint requires continued monitoring.     

Quality of life after knee revision arthroplasty

Background and purpose?Radiographic and clinical survival analyses of revision total knee replacement (TKR) are considered acceptable outcome measures. However, the full influence of revision knee replacement on the overall health status of patients remains poorly defined.

Methods?We prospectively studied the health-related quality of life outcome in 94 patients who underwent revision knee replacement surgery over a 5-year period. Comparisons were drawn between the Nottingham health profile (NHP) scores and the Knee Society score pre-revision, and those obtained at 3 months, 1 year and 5 years after revision knee arthroplasty.

Results?We found a significant improvement in Knee Society score and NHP pain scores 3 and 12 months after revision TKR (p < 0.05). No other modalities of the NHP showed a significant change. 5 years after surgery, pain was less than before revision (p = 0.2), but energy level was considered worse (p = 0.07). Knee Society scores were found to be higher pre- and postoperatively for patients undergoing revision for reasons other than sepsis than for patients with sepsis. Patients requiring implantation of a hinged prosthesis also had lower Knee Society scores than those patients receiving a non-hinged implant. Repeated revision was associated with a downward trend in Knee Society score with each surgical intervention.