Patella baja after total knee arthroplasty: is it really patella baja?

In the prosthetic knee, narrowing of the space between the patella and the tibial polyethylene can be due to distal positioning of the patella or to a proximal transfer of the joint line. In the former case, one is dealing with patella baja. In the latter case, the patella is in its normal position relative to the femur, a situation we call pseudo-patella baja. The therapeutic options for patella baja and pseudo-patella baja are different because the former is due to a short patellar tendon, and the latter is due to a raised joint line. Eversion of the extensor mechanism during revision surgery may be more challenging with true patella baja compared with pseudo-patella baja. It is important not to attempt to detect true patella baja with either the Blackburne-Peel or the Caton-Deschamps ratio in the setting of a prosthetic knee because these ratios are affected adversely by the position of the joint line.     

Hemophilus parainfluenzae complicating total knee arthroplasty. A case report

Infections are an unfortunate but well-known complication of prosthetic joint replacements. Prophylactic antibiotics have been prescribed to help combat infections in total joint arthroplasties. A 78-year-old woman with a cemented total knee replacement developed a Hemophilus parainfluenzae infection following routine root canal dental surgery. The infection was successfully treated with arthroscopic irrigation and antibiotic therapy.     

Patella in total knee arthroplasty

The patella is a reliable guide to the success or failure of a total knee replacement. Patients who do not experience peripatellar symptoms or a patellar complication usually have a successful result. Conversely, peripatellar symptoms or complications usually reflect an underlying problem with surgical technique, component designs, or both. Current designs still do not replicate normal kinematics, and current instrumentation and techniques significantly alter the anatomy of the patellofemoral articulation in a substantial percentage of patients. Reproducing extensor mechanism balance and using components that provide adequate congruency and contact area through a physiologic arc of motion should lead to a successful result with minimal patellar symptoms or complications whether or not the patella is resurfaced. Attempting to achieve normal patellofemoral kinematics and minimize patellar complications has led to a better understanding of total knee arthroplasty.     

Subluxation of the posterior stabilized total knee arthroplasty. A report of two cases.

There has been only one previous report of dislocation of a posteriorly stabilized total knee arthroplasty. The authors present two further cases of subluxation of this prosthesis and report a method of accomplishing reduction that could not otherwise be achieved by conventional techniques. The current design of this prosthesis enabled revision of the polyethylene tibial component to be undertaken without removal of the cemented metal-backing tray, an advantage not previously appreciated.     

全膝关节置换术后获得性低位髌骨的系统评价

目的：评价不同机制及干预措施在全膝关节置换术后发生低位髌骨的发生率。方法电子检索英文数据库：PUBMED、Cochrane Library、OVID、Springer-link;中文数据库中国知识资源总库（ CNKI）、万方学术期刊数据库、维普中文期刊数据库（ VIP）、中国生物医学文献服务系统（CBM）等作为资料来源,检索时间均从建库至2013年10月。评价纳入研究的质量,提取数据用Revman 5.1软件进行Meta分析。结果共纳入7个对照试验,615例患膝。合并结果表明,术前胫骨高位截骨与非胫骨高位截骨患者行全膝关节置换后低位髌骨的发生率相当[ RD＝0.19,95％CI （-0.30,0.69）]。术后髌腱短缩5％或10％诊断为获得性低位髌骨,避免髌骨外翻有利于减少低位髌骨的发生[RD＝-0.23,95％CI （-0.35,-0.11）],[RD＝-0.09,95％CI （-0.17,-0.00）]。不同干预措施术后Insall-Salvati指数比较无统计学差异。结论 TKA中避免髌骨外翻及髌下脂肪垫切除可能利于减少TKA术后低位髌骨的发生。尚不足证据证明术前行胫骨高位截骨及 TKA术中髌骨置换与否对术后发生低位髌骨的优劣。     

Retrieval analysis of porous-coated components for total knee arthroplasty. A report of two cases

Retrieval analysis of two total knee replacements incorporating porous-coated components for biologic fixation was performed. The significant finding in a 63-year-old woman was fracture of the porous-coated metal backing of the tibial component, secondary to aseptic loosening. The significant findings at the time of revision surgery in an 82-year-old woman were nonuniform bone ingrowth (primarily around fixation pegs) and fracture of metal beads from the metal backing of the patellar component.     

Gout-induced arthropathy after total knee arthroplasty: a report of two cases.

Gout, although relatively rare in joint replacements, can present as an acute or chronic painful knee or hip arthroplasty. Gout and acute infection of a joint replacement can be difficult to differentiate, with the physical examination and laboratory study results frequently being similar. Both conditions can present with a rapid onset of joint pain, swelling, erythema, and constitutional symptoms, including fevers and malaise. Laboratory findings in both conditions often include an elevated leukocyte count, erythrocyte sedimentation rate, and C-reactive protein level. Negatively birefringent, needle-shaped crystals in the synovial fluid confirm the diagnosis of gout. The mistaken diagnosis of septic arthritis in a joint replacement with crystal-induced synovitis can lead to inappropriate open debridement or component removal. The current study includes a review of the literature and presents two cases of gout after total knee arthroplasty. These cases suggest that in situations of suspected sepsis without synovial fluid crystals, operative intervention is indicated with a presumed diagnosis of septic arthritis. The identification of chalky white or yellow deposits in the synovium or bone is highly suggestive of gout. The definitive diagnosis is made by polarized light histologic evaluation of these tissues. If these deposits are present in the absence of a positive preoperative culture, positive Gram stain for bacteria, or component loosening, component retention is indicated.     

Dislocation of the posterior stabilized total knee arthroplasty: A report of two cases

This brief report details the previously unreported complication of dislocation of the posterior stabilized total knee arthroplasty. Both patients had valgus deformities requiring extensive release of the contracted lateral soft tissues. The mechanism of dislocation was one of slight flexion and external rotation. The prosthetic tibial spine became locked posterior to the femoral cam. Reduction was accomplished by applying traction and anterior translation on the tibia with the knee slightly flexed. No redislocations have occurred. A literature review is presented and the authors discuss technique modifications that may prevent this complication.     

Persistent infection after successful arthrodesis for infected total knee arthroplasty. A report of two cases

Infection in total knee arthroplasty has been reported to range from 1.1% to 12.4%. The literature contains numerous articles on salvage procedures including antibiotic suppression, surgical debridement, resection arthroplasty, arthrodesis, reimplantation, and amputation. Of those knees not reimplantable, a successful arthrodesis is felt by many to give the most predictable long-term results. The majority of literature on arthrodesis for infected total knee arthroplasty concentrates on technical factors and techniques to facilitate fusion. A successful fusion is considered an end point of treatment.     

Recalcitrant infection following total knee arthroplasty: a report of two cases

Infection following total knee arthroplasty can be devastating. Even with established treatment protocols, eradication of the infection may not be feasible. We report 2 patients who required above-knee amputation to eradicate recalcitrant infection.     

Periprosthetic fractures complicating total knee arthroplasty

Periprosthetic fractures complicating total knee arthroplasty (TKA) occur in rare cases. However, the rate of TKA continues to rise. Given the increase in demand, orthopedists, more than ever, will be responsible for evaluating and treating these fractures. In order to properly treat periprosthetic fractures, a level of comfort with the basic principles on this topic is critical. This article will discuss fractures affecting the femoral, tibial and patellar components along with the respective classification systems. The potential patient risk factors and post-operative rehabilitation guidelines are also discussed.     

Brucellosis complicating bilateral total knee arthroplasty

Infection after arthroplasty is a serious complication associated with a high incidence of morbidity. A 24-year-old woman developed brucella septic arthritis in both knees following bilateral total knee arthroplasty. This complication appears not to have been previously reported in the literature.     

Tuberculosis infection complicating total knee arthroplasty: report of 3 cases and review of the literature

The incidence of osteoarticular tuberculosis in the knee and other joints is increasing. Three cases of active tuberculous infection in the presence of a total knee prosthesis are presented. The pathology was not diagnosed until the prosthesis had been removed in 2 patients. They underwent antituberculous therapy and revision arthroplasty. In the third patient, the diagnosis was made early. Antituberculous therapy was begun immediately, and the original prosthesis was retained. Good long-term results were achieved in all 3 cases.     

Dislocation following total knee arthroplasty: A report of six cases

Background:

Dislocation following total knee arthroplasty (TKA) is the worst form of instability. The incidence is from 0.15 to 0.5%. We report six cases of TKA dislocation and analyze the patterns of dislocation and the factors related to each of them.

Materials and Methods:

Six patients with dislocation of knee following TKA are reported. The causes for the dislocations were an imbalance of the flexion gap (n=4), an inadequate selection of implants (n=1), malrotation of components (n=1) leading to incompetence of the extensor mechanism, or rupture of the medial collateral ligament (MCC). The patients presented complained of pain, giving way episodes, joint effusion and difficulty in climbing stairs. Five patients suffered posterior dislocation while one anterior dislocation. An urgent closed reduction of dislocation was performed under general anaesthesia in all patients. All patients were operated for residual instability by revision arthroplasty after a period of conservative treatment.

Results:

One patient had deep infection and knee was arthrodesed. Two patients have a minimal residual lag for active extension, including a patient with a previous patellectomy. Result was considered excellent or good in four cases and fair in one, without residual instability. Five out of six patients in our series had a cruciate retaining (CR) TKA designs: four were revised to a posterior stabilized (PS) TKA and one to a rotating hinge design because of the presence of a ruptured MCL.

Conclusion:

Further episodes of dislocation or instability will be prevented by identifying and treating major causes of instability. The increase in the level of constraint and correction of previous technical mistakes is mandatory.     

Patella inversion method for exposure in revision total knee arthroplasty.

Satisfactory performance of revision total knee arthroplasty (TKA) requires adequate exposure. This article shows the patella inversion method of exposure in a large consecutive series of revision TKAs.Between 1987 and 1999, 420 revision TKAs were performed. Exposure was facilitated by the patella inversion method. No attempt was made to evert the patella. This technique of exposure was used in 95% (397 of 420) of patients. There were no episodes of patellar tendon avulsion in this series. Multiple exposure options are available in revision TKA. Extensile techniques violate the extensor mechanism. For most patients, these methods were unnecessary. The patella inversion method afforded adequate exposure in most patients without violating the extensor mechanism.     

Arthroscopic irrigation and debridement of infected total knee arthroplasty: report of two cases

Various methods have been described for the treatment of the acutely infected total knee arthroplasty. These include antibiotic suppression, open debridement and irrigation, exchange arthroplasty, resection arthroplasty, arthrodesis, and amputation. A method not frequently reported is arthroscopic irrigation and debridement. Two cases of acutely infected total knee arthroplasty treated with arthroscopic irrigation and debridement are presented. In both cases there was a benign postoperative course averaging five months. Both infections were secondary to hematogenous seeding from a distant focus of infection. The patients presented within approximately 12 h after the onset of knee symptoms and were taken for arthroscopic irrigation and debridement within 12 h after presentation. Gram-positive organisms sensitive to the antibiotics being used were cultured in both. Postoperative knee function and range of motion returned rapidly and disability was minimal. At average 30-month follow-up both patients were pain free, had full activity of daily living, and had no clinical or radiographic evidence of infection. Arthroscopic irrigation and debridement appears to be an effective method of treatment in select cases of infected total knee arthroplasty.     

Recurvatum deformity complicating performance of total knee arthroplasty. A brief note

Recurvatum may be the rarest deformity complicating the performance of total knee arthroplasty. The cases of four patients--two who had a primary total knee arthroplasty and two, a revision--are described, as well as the measures that are needed to correct the malalignment while avoiding the use of a highly constrained prosthesis. The principal measure that is necessary is the positioning of one of the attachments of one or both collateral ligaments on the femur in order to recreate the normal tightening action as full extension of the knee is achieved.     

Enterocutaneous fistula complicating total hip arthroplasty. A case report.

This is a case report of an enterocutaneous fistula complicating total hip arthroplasty, an extremely rare but potentially fatal complication. A 76-year-old woman survived but required extensive prolonged surgical treatment.     

Primary total knee arthroplasty for displaced, acute intraarticular knee fractures. A report of four cases.

Primary total knee arthroplasty was performed in four patients with acute intraarticular fractures. All four were at high risk of failure for standard operative and nonoperative treatment because of severe osteopenia, preexisting intraarticular pathology, or a limited life expectancy. All benefited by early pain relief, functional range of motion, and early ambulation, with no early perioperative morbidity.