Patellar resurfacing in total knee arthroplasty leads to better isokinetic performance

BackgroundFor decades there have been concerns about patellar resurfacing (PR) in total knee arthroplasty (TKA) and the individual preference of the surgeon is still the main determinant of whether or not resurfacing is applied. According to preference, surgeons can be categorized in 3 main groups of those who usually, selectively, or rarely resurface. The aim of this prospective, randomized, controlled study was to compare the isokinetic performance and clinical outcome of TKAs with PR and without PR.MethodsA total of 50 patients scheduled to undergo TKA for primary osteoarthritis of the knee were randomly assigned to either the PR or non-PR groups. There were no significant differences between the groups in respect of age, BMI, gender and preoperative Knee Society Score (KSS) and isokinetic performance. Patients were evaluated at postoperative 3, 6, and 12 months with KSS and at 6 months and 1 year with isokinetic measurements.ResultsThe PR group had a higher mean score, especially in the functional component of KSS, but the difference was not statistically significant. Knee extension peak torque was significantly higher in the PR group at 6 months (p = 0.029) and 1 year (p = 0.004) postoperatively. There were no significant differences between the groups in respect of knee flexion peak torque values following TKA.ConclusionsThe results of this study demonstrated that PR during TKA is associated with better isokinetic performance and higher knee scores. These results support routine/usually resurfacing of the patella. For surgeons who selectively resurface the patella, the advantage of better isokinetic performance may be taking into consideration in favor of resurfacing the patella where they are undecided.Level of evidenceLevel I, therapeutic study.     

Evaluation and management of infected total knee arthroplasty

Infection after total knee arthroplasty is an infrequent but devastating complication. An understanding of the cause of infection, its diagnosis, and potential treatment options is essential to achieve a satisfactory result. The most successful treatment option is reimplantation with an 89% success rate of elimination of infection. However, some individuals require alternative salvage techniques.     

应用内轴膝人工膝关节置换的进展

人工膝关节置换(TKA)是治疗膝关节骨关节炎的重要手段。然而置换后的膝关节运动学不同于自然膝关节运动学,常出现反向前移,是影响患者满意度提高的重要原因。内轴膝关节假体在设计上能更好地模拟自然膝关节的运动,为TKA假体提供了较好的选择。本文对内轴膝关节的基本特点和临床应用效果及进展作一综述。     

Total knee arthroplasty using the total condylar III knee prosthesis

Twenty-seven total knee arthroplasties (TKAs) were performed in 24 patients using the total condylar III knee prosthesis (TCP III) and were evaluated clinically and radiographically with a mean follow-up period of 4 years. Eighteen were revision TKAs, and nine were primary knee arthroplasties. Evaluations were made using the Hospital for Special Surgery (HSS) knee scale as well as the Knee Society radiographic evaluation method. Clinical results for all knees were 11% (3 of 27) excellent, 70% (19 of 27) good, 15% (4 of 27) fair, and 4% (1 of 27) poor. The one poor rating resulted from an intraoperative vascular injury. The results showed no statistical difference between revision and primary TKA. After operation, pain relief, range of motion, walking, function, and activity level improved in both the primary and revision patients. Radiolucencies 2 mm or greater in width were found in 6 of the 27 tibial components, in none of the 27 femoral components, and in 1 of the 19 patellar components. Only two tibial implants showed progressive radiolucencies. No correlation was found between the radiographic position of the implants and the clinical results. The authors conclude that the TCP III is a satisfactory choice for TKA in selected knees in which there is significant instability and in which intramedullary fixation is required.     

Revision total knee arthroplasty using the total condylar III prosthesis

Implant selection for the severely damaged knee being treated by revision is difficult. Fixed or rotating hinges have provided mixed results with a high frequency of complication. An alternative to a hinge implant is the total condylar III prosthesis, which can substitute for a deficient collateral ligament. Between August 1980 and April 1987 total condylar III prostheses were used for revision of failed total knee arthroplasties (TKA) of 21 knees in 19 patients. In the same time interval, 649 TKA revisions were performed for a frequency of 3.2% using this prosthesis. The indications for using this prosthesis were bone loss in 10 knees, instability in 9 knees, supracondylar femur fracture in 1 knee, and implant malposition in one knee. At a 4-year follow-up evaluation the knee scores were excellent in 25%, good in 25%, fair in 25%, and poor in 25%. Complications occurred in 33% of the knees. The total condylar III prosthesis provided results similar to other constrained implants used for revision in patients with severe bone loss and ligamentous instability.     

国产人工膝关节系统初步应用的经验总结

目的总结初步使用国产TC-Dynamic人工膝关节系统的临床效果和手术经验。方法本组使用国产TC—Dynamic人工膝关节行全膝关节置换术（TKA）40例60膝，术前膝关节外科学会评分（KSS）的膝评分平均为16．28分（-32～47分），功能评分平均为18．36分（-20～60分），膝关节活动度（ROM）平均为79．22°（20°～145°）。结果36例52膝术后获得平均随访时间为20．41m（1．5～40m），随访时KSS膝评分平均为84．88分（70～95分），功能评分平均为80．58分（55～90分），ROM平均为110．48°（85°～140°）。所有随访患者术后X线片均示下肢力线良好，假体位置满意，无透亮线及任何松动迹象。结论使用国产TC—Dynamic人工膝关节假体的TKA手术临床效果满意。手术操作简便，截骨量较少，如果手术配套器械的设计和制作工艺能够进一步改良和提高，则更利于临床应用。     

Total knee arthroplasty using a total condylar prosthesis

The authors studied the cases of 52 patients (56 knees) treated with a total knee prosthesis of the type "total condylar" and "total condylar with posterior stabilization" over a 3-year period. Gonarthrosis (41 cases) and rheumatoid arthritis (12 cases) were the major indications. The analysis of functional results proves the success concerning mobility, pain and ability to negotiate stairs after knee arthroplasty. The postoperative radiological results of 44 knees were reviewed and compared to the literature. Proof of the importance of the postoperative axis and the inclination of the tibial component is provided. Few complications were observed. Review of the literature confirms the good results of this type of total knee prosthesis.     

Aggressive wear testing of a cross-linked polyethylene in total knee arthroplasty

Recently, highly cross-linked polyethylenes with high wear and oxidation resistance have been developed. These materials may improve the in vivo performance of polyethylene components used in total knee arthroplasty. To date, the in vitro knee wear testing of these new polyethylenes has been done under conditions of normal gait. However, their critical assessment also must include aggressive in vitro fatigue and wear testing. In the current study, an aggressive in vitro knee wear and device fatigue model simulating a tight posterior cruciate ligament balance during stair climbing was developed and used to assess the performance of one type of highly cross-linked polyethylene tibial knee insert in comparison with conventional polyethylene. The highly cross-linked inserts and one group of conventional inserts were tested after sterilization. One additional group of conventional inserts was subjected to accelerated aging before testing. The articular surfaces of the inserts were inspected visually for surface delamination, cracking, and pitting at regular intervals during the test. The aged conventional polyethylene inserts showed extensive delamination and cracking as early as 50,000 cycles. In contrast, the unaged conventional and highly cross-linked polyethylene inserts did not show any subsurface cracking or delamination at 0.5 million cycles. The appearance and location of delamination that occurred in the aged conventional inserts tested with the current model previously have been observed in vivo with posterior cruciate-sparing design knee arthroplasties with a tight posterior cruciate ligament.     

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.     

Revision total knee arthroplasty

Revision total knee arthroplasty presents numerous technical challenges and decisions for the operating surgeon. Preoperative planning includes critically reviewing radiographs and ordering necessary equipment, including prosthetic components, extraction devices, and bone graft materials. In some cases, surgical exposure requires the use of extensile exposure techniques. Component removal is facilitated by the use of appropriate tools (eg, specialized osteotomes) as well as by the patience to ensure preservation of host bone. Bone loss is managed with bone grafts or prosthetic augmentation. Attention to balancing the flexion and extension gaps is essential to avoid problems with instability as well as excessively constrained prosthetic components. Intramedullary stem extensions improve long-term clinical results. Intraoperative extensor mechanism complications can be avoided with meticulous surgical technique; late complications may require surgical intervention.     

Revision total knee arthroplasty

Revision total knee arthroplasty can be very successful if careful preoperative planning has been carried out and the surgeon is equipped to handle potential problems encountered with restoration of static alignment, stability, and deficient bone stock. Special femoral and tibial component extractors are indispensable tools. A high-speed burr is helpful. Posterior cruciate ligament-preserving prostheses often can be used, but prostheses with extra degrees of constraint must be available. Long-stemmed components for both the femoral and tibial sides should be available. Access to a bone bank to obtain allogeneic bone for grafting is essential. The surgeon must be familiar with techniques other than bone grafting for restoration of deficient stock, such as the use of bone screws and cement, custom-augmented components, and metal wedge spacers.     

Anametric total knee arthroplasty

The early experience with the anametric knee prosthesis shows it to be effective in achieving the aims desired in total knee arthroplasty. Decreased pain and improved function have been noted in most patients, with relatively few complications. In osteoarthritics, patellar replacement increases the level of improvement. This prosthetic system has been improved by the addition of further sizes and additional tibial fixation options. Detailed long-term follow-up evaluation of these patients will be necessary to judge the effectiveness of the newly introduced design modifications.     

Unicompartmental total knee arthroplasty

This article traces the evolution of unicondylar design and examines its indications, common aspects of surgical technique independent of design, results, and complications. The dichotomy of opinion concerning unicompartmental knee arthroplasty may reflect differences in patient selection, prosthesis selection, and surgical technique.     

Hybrid total knee arthroplasty

A prospective study of a hybrid total knee arthroplasty (TKA) with an uncemented femoral component and cemented tibial and patellar components was performed to combine the advantage of a press-fit femur while avoiding the problems in uncemented tibial and patellar implants. A total of 329 posterior cruciate-preserving TKA were studied at an average of 4.7 years after surgery: 84% of the knees had at most mild or occasional pain, 68% had good or excellent knee scores, and 62% could walk more than 1000 m. The function scores were 40% good or excellent in this collective, with an average age of 69.4 years at surgery. The component position and alignment were biomechanically correct. Radiolucent lines were observed regularly at the edges of the tibial and femoral components. There were no revisions for aseptic loosening. Hybrid TKA provides good results comparable to cemented TKA.     

Noncemented total knee arthroplasty

Extensive animal experimentation has proven porous titanium fiber composite to be an effective interface for direct attachment of prosthetic devices via bone ingrowth. Titanium has demonstrated excellent biocompatibility in long-term primate experiments. Utilizing this technology, a cementless total knee system has been developed. A pilot study of 34 knees demonstrated the feasibility of anchoring the tibial component without cement. A totally cementless unconstrained total knee replacement was designed with porous titanium fiber composite interfaces. Retention of the posterior cruciate ligament was an essential part of the design. A large range of sizes was chosen to allow precise fitting of individual patients with distribution of load over the maximum surface available. Early clinical results have been very encouraging. Patients have achieved excellent pain relief, rapid return of function, and range of motion exceeding previous designs.     

Evaluation of patient concerns before total knee and hip arthroplasty

The preoperative concerns of patients undergoing total knee or hip arthroplasty were evaluated in a cross-sectional study of 370 patients. Patients completed a questionnaire on 29 concerns, each rated on a scale of 1 (not concerned) to 4 (very concerned). Short Form 12 and Oxford hip or knee scores were also calculated. The results showed that the greatest concern for patients was cancellation of the surgery. This was followed by failure of the surgery to reduce pain, loss of a limb, and joint infection. Concerns regarding scar problems, nursing care, and preoperative tests were the lowest. Women showed statistically significant greater concerns in 9 areas. Younger patients (age, <65) showed increased concerns in 8 areas. Patients who had previously undergone joint arthroplasty were less concerned than those who had not undergone previous lower limb joint arthroplasty for 6 responses. They showed increased concern in 2 areas, nursing care and hospital food. Those undergoing total hip arthroplasty were more concerned about dislocation, dressing, and returning to work (all, P<.05). This study provides useful information for the preoperative counseling of patients and the production of preoperative literature.