169 C OPYRIGHT Ó 2014
BY
T HE J OURNAL
OF
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AND J OINT
S URGERY, I NCORPORATED
Specialty Update
What’s New in Adult Reconstructive Knee Surgery Carl Deirmengian, MD, and Jess H. Lonner, MD
The purpose of this update is to report on a variety of adult knee reconstruction topics published during the past year. The keywords ‘‘arthroplasty’’ and ‘‘knee’’ and ‘‘prospective’’ and ‘‘randomized’’ were utilized to query the PubMed database of the U.S. National Library of Medicine. From the resulting list, papers published from the beginning of July 2012 through the end of June 2013 in The Journal of Bone and Joint Surgery, The Bone & Joint Journal, or The Journal of Arthroplasty were reviewed to select prospective randomized studies in the field of adult knee reconstruction. Twenty-two of the resulting twenty-four studies are included in this update, and all twentyfour studies are listed in the bibliography at the end of this review1-24. Implant Choices The decision to use a certain implant during primary or revision total knee arthroplasty involves numerous considerations and preferences. While differing implant designs may possess certain theoretical benefits, only peer-reviewed outcome studies can truly reveal the benefits of a product. The following prospective randomized studies specifically compared differing implant designs with respect to the outcomes or findings after total knee arthroplasty. Three studies specifically tested the comparative outcomes of mobile-bearing technologies for total knee arthroplasty. Breeman et al.1 conducted a multicenter randomized controlled trial of mobile versus fixed-bearing total knee prostheses, including 539 patients. Multiple knee designs of both posterior cruciate-substituting and posterior cruciateSpecialty Update has been developed in collaboration with the Board of Specialty Societies (BOS) of the American Academy of Orthopaedic Surgeons.
retaining types were utilized in this study that comprised 276 mobile-bearing total knee implants and 263 fixed-bearing total knee implants. At a follow-up time of five years, the authors found no difference in the Oxford Knee Score, the Short-Form 12 (SF-12), health-related costs, or the need for reoperation between the two groups. In another randomized controlled trial, Nutton et al.2 studied seventy-seven patients who were randomly allocated to receive a standard fixed-bearing posterior cruciate-retaining design or a high-flexion, mobile-bearing posterior cruciatesubstituting design. After being followed for one year, patients were evaluated with the Knee Society rating system, the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index, and electrogoniometry to assess for knee motion during activities. This was a complex study, not only because of the many design differences between implants but also because of the numerous measurements and outcomes included. Nevertheless, at one year, the authors found that patients with a mobile-bearing posterior cruciate-substituting design had more pain than did those with a standard fixedbearing posterior cruciate-retaining design (mean pain score, 4.2 versus 2.5, respectively; p = 0.043). Furthermore, despite demonstrating a greater passive range of motion (113° versus 107°), patients with a mobile-bearing posterior cruciatesubstituting design actually exhibited a lower active range of motion during level walking and ascending a slope. Additionally, Pijls et al.3 conducted a randomized controlled trial of mobile-bearing versus fixed-bearing designs, specifically focusing on wear and fixation at ten to twelve years. Both groups included twenty-one patients, and all patients were assessed with use of radiostereometric analysis and the Knee Society rating system. Their study revealed no clinical
Disclosure: One or more of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of an aspect of this work. In addition, one or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2014;96:169-74
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What’s New in Adult Reconstructive Knee Surgery differences between groups and also showed no difference in the migration of implants between the two groups. The mean linear wear rate of the undersurface of the polyethylene insert was 0.026 mm per year for the mobile-bearing group as compared with 0.11 mm per year for the fixed-bearing group, which the authors acknowledged was not clinically significant. The lack of clinical significance was despite the fact that the fixed-bearing polyethylene was gamma sterilized in air whereas the mobile-bearing insert was gamma sterilized in inert gas. Therefore, even in a best-case scenario for mobile-bearing technologies, there is no apparent benefit to the fixation or wear of the implant at ten years after total knee arthroplasty. Although mobile-bearing knees have several potential theoretical advantages, the randomized controlled trials continue to demonstrate no significant differences with regard to outcome, function, or survivorship due to this technology. Two additional studies addressed implant-related hypotheses. In the largest randomized controlled trial to date that evaluates the possible benefits of an oxidized zirconium femoral implant, Kim et al.4 used a randomized bilateral knee model to prospectively study knees that had an oxidized zirconium femur as compared with those that had a standard cobalt-chromium implant. At a mean of 7.5 years after total knee arthroplasty, patients were assessed with use of the Knee Society rating system and the WOMAC osteoarthritis index as well as with methods of measuring active knee motion, patient satisfaction, activity, knee preference, and radiographic outcome. One-hundred and twenty patients (240 knees) underwent knee aspiration to evaluate the wear particles present. At the most recent follow-up, the authors found no difference in patient preference for either implant type, nor did they find any difference in survivorship, clinical outcome, or wear particles aspirated. The authors concluded that the oxidized zirconium femoral implant does not provide any benefit to the patient, and they questioned the additional expense of such implants. In a separate study, Jensen et al.5 conducted a randomized trial comparing ten revision total knee implants with a tibial trabecular metal cone to eleven revision total knee implants without a tibial trabecular metal cone. At twenty-four months, radiostereometric analysis was utilized to assess micromotion between the implant and host bone. In comparison with the use of revision tibial implants without a trabecular metal cone, the use of revision tibial implants with a trabecular metal cone demonstrated a trend toward earlier implant stabilization and resulted in less irregularity in the migration pattern, although significant differences could not be achieved. Further study is likely necessary however, given the relatively low number of patients and the lack of power that was demonstrated. Alignment The subject of alignment after total knee arthroplasty has been recently debated, with some doubting the long-held belief that longevity and function after knee replacement are optimal
at a neutral mechanical axis. This topic is of special importance to proponents of computer navigation, who aim to achieve a mechanical axis more consistently. Additionally, the subject of alignment is critical for those who are testing the success of total knee prostheses that were implanted to achieve anatomic alignment. Kim et al.6 reported on a prospective randomized study in which navigated total knee arthroplasty was compared with conventional total knee arthroplasty in a bilateral model including 520 patients. They followed patients having a posterior cruciate-retaining mobile-bearing total knee arthroplasty for a mean of 10.8 years, evaluating outcomes with use of the Knee Society rating system, the WOMAC osteoarthritis index, radiographs, and measures of activity level, knee motion, and survivorship. Radiographic evaluation of knees revealed no significant differences between groups with regard to the number of outliers or the average mechanical axis. Furthermore, clinical evaluations revealed no significant differences in pain, function, clinical scores, or survivorship, which was 99% in both groups. The authors concluded that navigation does not improve alignment or any clinical outcome after total knee arthroplasty. Huang et al.7 also evaluated navigation in a prospective randomized controlled trial that included ninety patients with five-year follow-up. The International Knee Society knee scoring system, the SF-12, and radiographic evaluation were completed to assess if there were any advantages in using navigated total knee arthroplasty rather than conventional total knee arthroplasty. The authors found that knees receiving navigated total knee arthroplasty had a higher rate of alignment to within 3° of the mechanical axis (91% for the navigated arthroplasty group versus 61% for the conventional arthroplasty group, p = 0.002). Patients within 3° of a neutral mechanical axis had better International Knee Society knee scores at two years (a score of 45 as compared with a score of 34, p = 0.015) and better SF-12 scores at almost every follow-up interval (p < 0.05). It was concluded that navigation reduced outliers from the mechanical axis, and also that total knee implants that were aligned within 3° of the mechanical axis had better outcomes. Nevertheless, the authors emphasized that many factors beyond alignment influence outcomes after total knee arthroplasty. In a study in which knees were randomly assigned to mechanical or anatomic alignment, Yim et al.8 used navigation to implant fifty-six total knee prostheses in mechanical alignment and sixty-one total knee prostheses in anatomic alignment, which places the tibial cut in 2° of varus and the distal femoral cut in 2° of valgus. Patients were followed for a minimum of two years and were assessed for laxity, knee motion, Hospital for Special Surgery score, and WOMAC scores. The authors were able to achieve their desired alignment goals, as both groups had a neutral mechanical axis but revealed a two-degree difference in implant alignment as intended. At the most recent follow-up, there was no difference in any clinical score or outcome, and both groups demonstrated
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What’s New in Adult Reconstructive Knee Surgery equivalent stability of the total knee implant. It was concluded that implanting a total knee prosthesis in anatomic alignment does not improve or harm clinical outcomes. In addition to navigation, the emergence of patient-specific cutting guides has also offered a method of potentially improving on the conventional accuracy in achieving limb alignment after total knee arthroplasty. Chareancholvanich et al.9 reported on a prospective randomized study in which patient-specific cutting guides were compared with conventional jig-based methods of total knee arthroplasty. The only outcomes measured were radiographic ones, including implant and limb alignment. All guides were utilized to achieve a neutral mechanical axis. The forty total knee prostheses that had been implanted with use of patient-specific cutting guides revealed no significant improvement with regard to limb or implant alignment when compared with the knees that had been implanted with use of conventional methods, except for a 0.7° improvement in coronal tibial alignment, which was considered clinically insignificant. There was also no significant difference in the number of outliers, raising considerable doubt regarding the clinical relevance of this technology. Intraoperative Products There are an abundance of products that can be administered intraoperatively to a patient in an attempt to diminish complications, improve outcomes, or facilitate surgery. Many of these products target pain, nausea, bleeding, and wound closure but contribute to the increasing cost of total knee arthroplasty. The following studies evaluated intraoperatively administered products in an attempt to improve total knee arthroplasty. Many products, some at a significant cost, are intended to reduce bleeding during and after total knee arthroplasty. Kim et al.10 conducted a prospective randomized controlled trial evaluating the efficacy of Floseal (Baxter, Deerfield, Illinois), a thrombin-based hemostatic agent. The authors applied Floseal randomly to ninety-seven of 196 patients having a total knee arthroplasty, directing the agent at exposed bone and soft tissues. Outcomes included drain output at twenty-four hours, transfusion requirements, change in hemoglobin and hematocrit, pain, knee motion, and complications. Data analysis revealed no clinically relevant differences between groups, as the drain output at twenty-four hours and transfusion rate were equivalent. Although Floseal appeared to be safe, the authors reported that there did not appear to be any clinical benefits that would merit the cost of the product. Lin et al.11 studied the efficacy of tranexamic acid in a prospective randomized controlled study. They randomly assigned 151 patients having unilateral total knee arthroplasty to one of three groups: a placebo group, a one-dose tranexamic acid (10 mg/kg intraoperatively) group, or a two-dose (10 mg/kg preoperatively and intraoperatively) tranexamic acid group. The authors recorded the volume of blood loss and the number of transfusions after total knee arthroplasty, and they also
recorded any thromboembolic events. Although there was no significant difference between tranexamic acid dosage groups, the placebo group had a significantly higher mean total blood loss (1222 mL in the placebo group versus 1035 mL in the one-dose group and 986 mL in the twodose group, p < 0.0001) and also a significantly higher transfusion rate (22% versus 3.8% and 6.1%, respectively; p = 0.041). Only one patient in the study had a deep venous thrombosis. It appears that tranexamic acid is a safe and effective drug that can be administered during total knee arthroplasty to conserve blood and reduce the transfusion rate. Products aimed at wound closure usually aim to quicken the rate of closure or improve the strength and cosmesis of the closure. Ting et al.12 evaluated the Quill (Angiotech, Vancouver, British Columbia, Canada) knotless suture for closure of total hip arthroplasty and total knee arthroplasty. Barbed, knotless sutures have the theoretical advantages of increased speed, increased strength, and reduced ‘‘spitting’’ of sutures. This prospective randomized study included seventeen patients in whom all layers were closed with Quill and eighteen patients in whom closure was performed in a traditional layered manner. The authors compared the time to closure, the length of surgery, and the complications between patient groups. They found that closure after total knee arthroplasty was a mean of 3.5 minutes faster (p = 0.0172) and that there was no difference in the rate of wound complications postoperatively. Although the use of a barbed suture in total knee arthroplasty was associated with a $43 increased cost, the authors calculated a $364 cost savings when the amount of operative time that was saved was considered. Although this study demonstrated that knotless sutures may provide significant time savings during total knee arthroplasty, especially at high-volume centers, larger studies are needed to make firm conclusions about safety. El-Gazzar et al.13 evaluated the use of Dermabond (Ethicon, Somerville, New Jersey) tissue adhesive during closure of the skin during total knee arthroplasty. In a randomized prospective manner, twenty-five patients received the Dermabond adhesive after a stapled closure, and twenty-one patients received no adhesive after a stapled closure. Low molecular-weight heparin was used for thromboprophylaxis in all patients. A standard gauze dressing was utilized and changed on postoperative days 2 and 3, and a graph-paper method was used to quantify the drainage area on five layers of the gauze dressing. The authors found that the total drainage from total knee arthroplasty wounds treated with Dermabond was significantly less than the total drainage from total knee arthroplasty wounds without Dermabond (153 versus 657 gauze area units, p < 0.001). Although the cost of Dermabond is about $33 per application, the large reduction of drainage after total knee arthroplasty may reduce the consequent complications of drainage that have been described in the literature, including infection, length of hospital stay, and, potentially, hospital readmission.
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What’s New in Adult Reconstructive Knee Surgery There are two additional, unrelated studies that evaluated intraoperative products for total knee arthroplasty. Hinarejos et al.14 conducted a prospective randomized study in Spain, comparing regular bone cement to antibiotic-loaded bone cement containing 0.5 mg of erythromycin and three million units of colistin per 40 g of cement. This large study included 2948 total knee arthroplasties, and patients were randomized intraoperatively with use of a computer-generated random number. No body exhaust suits were used, and all arthroplasties were completed in the same surgical suite. At a followup of twelve months, the overall deep infection rate after total knee arthroplasty was 1.36%, with no differences in superficial or deep infections between groups receiving regular or antibiotic-loaded bone cement. Although the results of this excellent study cannot be extended to bone cements containing different antibiotics, it is quite clear from this study that the antibiotic bone cement chosen did not have any influence on postoperative outcomes related to infection. In a different study, Jules-Elysee et al.15 studied the effect of perioperative intravenous hydrocortisone on systemic inflammation, pain, fever, and outcomes resulting from bilateral total knee arthroplasty. This prospective study included seventeen control patients and seventeen patients receiving three doses of parenteral hydrocortisone (100 mg) at eight-hour intervals starting two hours prior to surgery. The authors found that serum levels of interleukin-6 (IL-6) and urinary desmosine, both indicators of systemic inflammation, were dramatically elevated in patients in the control group, whereas patients receiving hydrocortisone had unchanged levels of urinary desmosine and slightly elevated serum levels of IL-6 at twentyfour hours postoperatively. Furthermore, pain scores were significantly lower in the study group (1.4 versus 2.4, p = 0.01) as was the rate of postoperative fever (11.8% versus 47.1%, p = 0.03). The authors also noted that postoperative glucose levels were elevated in the group receiving hydrocortisone, although no infections or problems with wound-healing were seen. This interesting study appears to have identified a method of decreasing systemic inflammation after bilateral total knee arthroplasty, which could significantly improve comfort and outcomes after this procedure. Caution should be taken until larger studies reveal that the infection rate does not rise in patients receiving perioperative hydrocortisone. Intraoperative Techniques In addition to the administration of various intraoperative products, there are also various described intraoperative techniques that attempt to improve outcomes or facilitate surgery. These include surgical approaches and specific surgical techniques. Interestingly, the literature has recently lacked the abundance of randomized prospective studies on minimally invasive approaches that was observed over the last decade, likely because the overwhelming majority of these studies had failed to demonstrate clinically significant advantages but did find elevated rates of complication. The following studies
evaluate intraoperative techniques that may improve outcomes or facilitate the surgeon during total knee arthroplasty. Stevens-Lapsley et al.16 compared a conventional medial parapatellar approach (6 cm superior to the patella) to an abbreviated medial parapatellar approach (only 1 cm superior to the patella). Their randomized study included twenty-two patients having the conventional approach and twenty-two patients having the ‘‘minimally invasive’’ approach, with several follow-up visits over the course of twelve weeks, during which the patients were assessed with regard to muscle strength, functional performance, pain, knee motion, muscle mass, and SF-36 and WOMAC scores. The only significant difference between patient groups occurred at four weeks postoperatively, with patients who had the abbreviated medial parapatellar approach demonstrating a small advantage in hamstring strength (p = 0.02); however, this did not translate into any functional outcome differences. There was no difference in blood loss or length of hospital stay. It is clear from this study, and from the abundance of other prospective randomized studies in the literature, that minimally invasive approaches to total knee arthroplasty do not result in any improved early or late outcomes that would be considered clinically relevant. The use of peripatellar electrocautery was studied by Baliga et al.17, who included 185 patients having a total knee arthroplasty without patellar resurfacing. There is a theoretical possibility that peripatellar electrocautery would denervate the patella and reduce the incidence of postoperative pain in the anterior aspect of the knee. The study group of ninety-one patients received the treatment just before wound closure in this patient-blinded and assessor-blinded study. The authors followed patients for one year, making assessments with use of the Oxford Knee Score and a pain score for pain in the anterior aspect of the knee. The results indicated no significant differences between the groups with regard to any outcome measure, which led to the conclusion that peripatellar electrocautery does not reduce pain in the anterior aspect of the knee after total knee arthroplasty. Two studies specifically focused on the efficacy and utility of tourniquet use during total knee arthroplasty. Tai et al.18 conducted a prospective randomized controlled trial comparing thirty-six knees undergoing total knee arthroplasty performed with the use of a tourniquet to thirty-six knees undergoing total knee arthroplasty performed without use of a tourniquet. Tourniquets were set to a pressure of 100 mm Hg above the systolic pressure in the study group. Outcomes included blood loss, pain scores, thigh circumference, and levels of hemoglobin, hematocrit, serum creatine phosphokinase, myoglobin, C-reactive protein, and lactate dehydrogenase. The mean tourniquet time was fifty-three minutes, and the study group receiving tourniquet use demonstrated significant smaller decreases in postoperative hemoglobin (2.6 versus 3.7 g/dL, p < 0.001) and hematocrit (7.6% versus 10.4%, p = 0.001) on postoperative day 4, although there was no difference in the transfusion rate. Both the C-reactive protein and creatine phosphokinase were higher in the
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What’s New in Adult Reconstructive Knee Surgery nontourniquet group on postoperative day 2, demonstrating greater injury and inflammation without a tourniquet. On postoperative day 4, the study group receiving tourniquets did have a statistically significant higher pain level (p < 0.05), although the difference of 0.5 on the pain scale may not be clinically significant. These authors concluded that, due to the lack of clinically relevant differences between groups, they could not recommend for or against tourniquets. Olivecrona et al.19 also studied tourniquet use, specifically questioning the efficacy and utility of using the limb-occlusion-pressure (LOP) method compared with the routine method in which the tourniquet cuff pressure is based on the systolic blood pressure of the patient. They randomized 161 patients into each group, measuring postoperative pain, motion, and wound-related complications. Patients with a tourniquet pressure calculated by the LOP method more frequently had a cuff pressure set at
BY
T HE J OURNAL
OF
B ONE
AND J OINT
S URGERY, I NCORPORATED
Specialty Update
What’s New in Adult Reconstructive Knee Surgery Carl Deirmengian, MD, and Jess H. Lonner, MD
The purpose of this update is to report on a variety of adult knee reconstruction topics published during the past year. The keywords ‘‘arthroplasty’’ and ‘‘knee’’ and ‘‘prospective’’ and ‘‘randomized’’ were utilized to query the PubMed database of the U.S. National Library of Medicine. From the resulting list, papers published from the beginning of July 2012 through the end of June 2013 in The Journal of Bone and Joint Surgery, The Bone & Joint Journal, or The Journal of Arthroplasty were reviewed to select prospective randomized studies in the field of adult knee reconstruction. Twenty-two of the resulting twenty-four studies are included in this update, and all twentyfour studies are listed in the bibliography at the end of this review1-24. Implant Choices The decision to use a certain implant during primary or revision total knee arthroplasty involves numerous considerations and preferences. While differing implant designs may possess certain theoretical benefits, only peer-reviewed outcome studies can truly reveal the benefits of a product. The following prospective randomized studies specifically compared differing implant designs with respect to the outcomes or findings after total knee arthroplasty. Three studies specifically tested the comparative outcomes of mobile-bearing technologies for total knee arthroplasty. Breeman et al.1 conducted a multicenter randomized controlled trial of mobile versus fixed-bearing total knee prostheses, including 539 patients. Multiple knee designs of both posterior cruciate-substituting and posterior cruciateSpecialty Update has been developed in collaboration with the Board of Specialty Societies (BOS) of the American Academy of Orthopaedic Surgeons.
retaining types were utilized in this study that comprised 276 mobile-bearing total knee implants and 263 fixed-bearing total knee implants. At a follow-up time of five years, the authors found no difference in the Oxford Knee Score, the Short-Form 12 (SF-12), health-related costs, or the need for reoperation between the two groups. In another randomized controlled trial, Nutton et al.2 studied seventy-seven patients who were randomly allocated to receive a standard fixed-bearing posterior cruciate-retaining design or a high-flexion, mobile-bearing posterior cruciatesubstituting design. After being followed for one year, patients were evaluated with the Knee Society rating system, the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index, and electrogoniometry to assess for knee motion during activities. This was a complex study, not only because of the many design differences between implants but also because of the numerous measurements and outcomes included. Nevertheless, at one year, the authors found that patients with a mobile-bearing posterior cruciate-substituting design had more pain than did those with a standard fixedbearing posterior cruciate-retaining design (mean pain score, 4.2 versus 2.5, respectively; p = 0.043). Furthermore, despite demonstrating a greater passive range of motion (113° versus 107°), patients with a mobile-bearing posterior cruciatesubstituting design actually exhibited a lower active range of motion during level walking and ascending a slope. Additionally, Pijls et al.3 conducted a randomized controlled trial of mobile-bearing versus fixed-bearing designs, specifically focusing on wear and fixation at ten to twelve years. Both groups included twenty-one patients, and all patients were assessed with use of radiostereometric analysis and the Knee Society rating system. Their study revealed no clinical
Disclosure: One or more of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of an aspect of this work. In addition, one or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
J Bone Joint Surg Am. 2014;96:169-74
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http://dx.doi.org/10.2106/JBJS.M.01255
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What’s New in Adult Reconstructive Knee Surgery differences between groups and also showed no difference in the migration of implants between the two groups. The mean linear wear rate of the undersurface of the polyethylene insert was 0.026 mm per year for the mobile-bearing group as compared with 0.11 mm per year for the fixed-bearing group, which the authors acknowledged was not clinically significant. The lack of clinical significance was despite the fact that the fixed-bearing polyethylene was gamma sterilized in air whereas the mobile-bearing insert was gamma sterilized in inert gas. Therefore, even in a best-case scenario for mobile-bearing technologies, there is no apparent benefit to the fixation or wear of the implant at ten years after total knee arthroplasty. Although mobile-bearing knees have several potential theoretical advantages, the randomized controlled trials continue to demonstrate no significant differences with regard to outcome, function, or survivorship due to this technology. Two additional studies addressed implant-related hypotheses. In the largest randomized controlled trial to date that evaluates the possible benefits of an oxidized zirconium femoral implant, Kim et al.4 used a randomized bilateral knee model to prospectively study knees that had an oxidized zirconium femur as compared with those that had a standard cobalt-chromium implant. At a mean of 7.5 years after total knee arthroplasty, patients were assessed with use of the Knee Society rating system and the WOMAC osteoarthritis index as well as with methods of measuring active knee motion, patient satisfaction, activity, knee preference, and radiographic outcome. One-hundred and twenty patients (240 knees) underwent knee aspiration to evaluate the wear particles present. At the most recent follow-up, the authors found no difference in patient preference for either implant type, nor did they find any difference in survivorship, clinical outcome, or wear particles aspirated. The authors concluded that the oxidized zirconium femoral implant does not provide any benefit to the patient, and they questioned the additional expense of such implants. In a separate study, Jensen et al.5 conducted a randomized trial comparing ten revision total knee implants with a tibial trabecular metal cone to eleven revision total knee implants without a tibial trabecular metal cone. At twenty-four months, radiostereometric analysis was utilized to assess micromotion between the implant and host bone. In comparison with the use of revision tibial implants without a trabecular metal cone, the use of revision tibial implants with a trabecular metal cone demonstrated a trend toward earlier implant stabilization and resulted in less irregularity in the migration pattern, although significant differences could not be achieved. Further study is likely necessary however, given the relatively low number of patients and the lack of power that was demonstrated. Alignment The subject of alignment after total knee arthroplasty has been recently debated, with some doubting the long-held belief that longevity and function after knee replacement are optimal
at a neutral mechanical axis. This topic is of special importance to proponents of computer navigation, who aim to achieve a mechanical axis more consistently. Additionally, the subject of alignment is critical for those who are testing the success of total knee prostheses that were implanted to achieve anatomic alignment. Kim et al.6 reported on a prospective randomized study in which navigated total knee arthroplasty was compared with conventional total knee arthroplasty in a bilateral model including 520 patients. They followed patients having a posterior cruciate-retaining mobile-bearing total knee arthroplasty for a mean of 10.8 years, evaluating outcomes with use of the Knee Society rating system, the WOMAC osteoarthritis index, radiographs, and measures of activity level, knee motion, and survivorship. Radiographic evaluation of knees revealed no significant differences between groups with regard to the number of outliers or the average mechanical axis. Furthermore, clinical evaluations revealed no significant differences in pain, function, clinical scores, or survivorship, which was 99% in both groups. The authors concluded that navigation does not improve alignment or any clinical outcome after total knee arthroplasty. Huang et al.7 also evaluated navigation in a prospective randomized controlled trial that included ninety patients with five-year follow-up. The International Knee Society knee scoring system, the SF-12, and radiographic evaluation were completed to assess if there were any advantages in using navigated total knee arthroplasty rather than conventional total knee arthroplasty. The authors found that knees receiving navigated total knee arthroplasty had a higher rate of alignment to within 3° of the mechanical axis (91% for the navigated arthroplasty group versus 61% for the conventional arthroplasty group, p = 0.002). Patients within 3° of a neutral mechanical axis had better International Knee Society knee scores at two years (a score of 45 as compared with a score of 34, p = 0.015) and better SF-12 scores at almost every follow-up interval (p < 0.05). It was concluded that navigation reduced outliers from the mechanical axis, and also that total knee implants that were aligned within 3° of the mechanical axis had better outcomes. Nevertheless, the authors emphasized that many factors beyond alignment influence outcomes after total knee arthroplasty. In a study in which knees were randomly assigned to mechanical or anatomic alignment, Yim et al.8 used navigation to implant fifty-six total knee prostheses in mechanical alignment and sixty-one total knee prostheses in anatomic alignment, which places the tibial cut in 2° of varus and the distal femoral cut in 2° of valgus. Patients were followed for a minimum of two years and were assessed for laxity, knee motion, Hospital for Special Surgery score, and WOMAC scores. The authors were able to achieve their desired alignment goals, as both groups had a neutral mechanical axis but revealed a two-degree difference in implant alignment as intended. At the most recent follow-up, there was no difference in any clinical score or outcome, and both groups demonstrated
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What’s New in Adult Reconstructive Knee Surgery equivalent stability of the total knee implant. It was concluded that implanting a total knee prosthesis in anatomic alignment does not improve or harm clinical outcomes. In addition to navigation, the emergence of patient-specific cutting guides has also offered a method of potentially improving on the conventional accuracy in achieving limb alignment after total knee arthroplasty. Chareancholvanich et al.9 reported on a prospective randomized study in which patient-specific cutting guides were compared with conventional jig-based methods of total knee arthroplasty. The only outcomes measured were radiographic ones, including implant and limb alignment. All guides were utilized to achieve a neutral mechanical axis. The forty total knee prostheses that had been implanted with use of patient-specific cutting guides revealed no significant improvement with regard to limb or implant alignment when compared with the knees that had been implanted with use of conventional methods, except for a 0.7° improvement in coronal tibial alignment, which was considered clinically insignificant. There was also no significant difference in the number of outliers, raising considerable doubt regarding the clinical relevance of this technology. Intraoperative Products There are an abundance of products that can be administered intraoperatively to a patient in an attempt to diminish complications, improve outcomes, or facilitate surgery. Many of these products target pain, nausea, bleeding, and wound closure but contribute to the increasing cost of total knee arthroplasty. The following studies evaluated intraoperatively administered products in an attempt to improve total knee arthroplasty. Many products, some at a significant cost, are intended to reduce bleeding during and after total knee arthroplasty. Kim et al.10 conducted a prospective randomized controlled trial evaluating the efficacy of Floseal (Baxter, Deerfield, Illinois), a thrombin-based hemostatic agent. The authors applied Floseal randomly to ninety-seven of 196 patients having a total knee arthroplasty, directing the agent at exposed bone and soft tissues. Outcomes included drain output at twenty-four hours, transfusion requirements, change in hemoglobin and hematocrit, pain, knee motion, and complications. Data analysis revealed no clinically relevant differences between groups, as the drain output at twenty-four hours and transfusion rate were equivalent. Although Floseal appeared to be safe, the authors reported that there did not appear to be any clinical benefits that would merit the cost of the product. Lin et al.11 studied the efficacy of tranexamic acid in a prospective randomized controlled study. They randomly assigned 151 patients having unilateral total knee arthroplasty to one of three groups: a placebo group, a one-dose tranexamic acid (10 mg/kg intraoperatively) group, or a two-dose (10 mg/kg preoperatively and intraoperatively) tranexamic acid group. The authors recorded the volume of blood loss and the number of transfusions after total knee arthroplasty, and they also
recorded any thromboembolic events. Although there was no significant difference between tranexamic acid dosage groups, the placebo group had a significantly higher mean total blood loss (1222 mL in the placebo group versus 1035 mL in the one-dose group and 986 mL in the twodose group, p < 0.0001) and also a significantly higher transfusion rate (22% versus 3.8% and 6.1%, respectively; p = 0.041). Only one patient in the study had a deep venous thrombosis. It appears that tranexamic acid is a safe and effective drug that can be administered during total knee arthroplasty to conserve blood and reduce the transfusion rate. Products aimed at wound closure usually aim to quicken the rate of closure or improve the strength and cosmesis of the closure. Ting et al.12 evaluated the Quill (Angiotech, Vancouver, British Columbia, Canada) knotless suture for closure of total hip arthroplasty and total knee arthroplasty. Barbed, knotless sutures have the theoretical advantages of increased speed, increased strength, and reduced ‘‘spitting’’ of sutures. This prospective randomized study included seventeen patients in whom all layers were closed with Quill and eighteen patients in whom closure was performed in a traditional layered manner. The authors compared the time to closure, the length of surgery, and the complications between patient groups. They found that closure after total knee arthroplasty was a mean of 3.5 minutes faster (p = 0.0172) and that there was no difference in the rate of wound complications postoperatively. Although the use of a barbed suture in total knee arthroplasty was associated with a $43 increased cost, the authors calculated a $364 cost savings when the amount of operative time that was saved was considered. Although this study demonstrated that knotless sutures may provide significant time savings during total knee arthroplasty, especially at high-volume centers, larger studies are needed to make firm conclusions about safety. El-Gazzar et al.13 evaluated the use of Dermabond (Ethicon, Somerville, New Jersey) tissue adhesive during closure of the skin during total knee arthroplasty. In a randomized prospective manner, twenty-five patients received the Dermabond adhesive after a stapled closure, and twenty-one patients received no adhesive after a stapled closure. Low molecular-weight heparin was used for thromboprophylaxis in all patients. A standard gauze dressing was utilized and changed on postoperative days 2 and 3, and a graph-paper method was used to quantify the drainage area on five layers of the gauze dressing. The authors found that the total drainage from total knee arthroplasty wounds treated with Dermabond was significantly less than the total drainage from total knee arthroplasty wounds without Dermabond (153 versus 657 gauze area units, p < 0.001). Although the cost of Dermabond is about $33 per application, the large reduction of drainage after total knee arthroplasty may reduce the consequent complications of drainage that have been described in the literature, including infection, length of hospital stay, and, potentially, hospital readmission.
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What’s New in Adult Reconstructive Knee Surgery There are two additional, unrelated studies that evaluated intraoperative products for total knee arthroplasty. Hinarejos et al.14 conducted a prospective randomized study in Spain, comparing regular bone cement to antibiotic-loaded bone cement containing 0.5 mg of erythromycin and three million units of colistin per 40 g of cement. This large study included 2948 total knee arthroplasties, and patients were randomized intraoperatively with use of a computer-generated random number. No body exhaust suits were used, and all arthroplasties were completed in the same surgical suite. At a followup of twelve months, the overall deep infection rate after total knee arthroplasty was 1.36%, with no differences in superficial or deep infections between groups receiving regular or antibiotic-loaded bone cement. Although the results of this excellent study cannot be extended to bone cements containing different antibiotics, it is quite clear from this study that the antibiotic bone cement chosen did not have any influence on postoperative outcomes related to infection. In a different study, Jules-Elysee et al.15 studied the effect of perioperative intravenous hydrocortisone on systemic inflammation, pain, fever, and outcomes resulting from bilateral total knee arthroplasty. This prospective study included seventeen control patients and seventeen patients receiving three doses of parenteral hydrocortisone (100 mg) at eight-hour intervals starting two hours prior to surgery. The authors found that serum levels of interleukin-6 (IL-6) and urinary desmosine, both indicators of systemic inflammation, were dramatically elevated in patients in the control group, whereas patients receiving hydrocortisone had unchanged levels of urinary desmosine and slightly elevated serum levels of IL-6 at twentyfour hours postoperatively. Furthermore, pain scores were significantly lower in the study group (1.4 versus 2.4, p = 0.01) as was the rate of postoperative fever (11.8% versus 47.1%, p = 0.03). The authors also noted that postoperative glucose levels were elevated in the group receiving hydrocortisone, although no infections or problems with wound-healing were seen. This interesting study appears to have identified a method of decreasing systemic inflammation after bilateral total knee arthroplasty, which could significantly improve comfort and outcomes after this procedure. Caution should be taken until larger studies reveal that the infection rate does not rise in patients receiving perioperative hydrocortisone. Intraoperative Techniques In addition to the administration of various intraoperative products, there are also various described intraoperative techniques that attempt to improve outcomes or facilitate surgery. These include surgical approaches and specific surgical techniques. Interestingly, the literature has recently lacked the abundance of randomized prospective studies on minimally invasive approaches that was observed over the last decade, likely because the overwhelming majority of these studies had failed to demonstrate clinically significant advantages but did find elevated rates of complication. The following studies
evaluate intraoperative techniques that may improve outcomes or facilitate the surgeon during total knee arthroplasty. Stevens-Lapsley et al.16 compared a conventional medial parapatellar approach (6 cm superior to the patella) to an abbreviated medial parapatellar approach (only 1 cm superior to the patella). Their randomized study included twenty-two patients having the conventional approach and twenty-two patients having the ‘‘minimally invasive’’ approach, with several follow-up visits over the course of twelve weeks, during which the patients were assessed with regard to muscle strength, functional performance, pain, knee motion, muscle mass, and SF-36 and WOMAC scores. The only significant difference between patient groups occurred at four weeks postoperatively, with patients who had the abbreviated medial parapatellar approach demonstrating a small advantage in hamstring strength (p = 0.02); however, this did not translate into any functional outcome differences. There was no difference in blood loss or length of hospital stay. It is clear from this study, and from the abundance of other prospective randomized studies in the literature, that minimally invasive approaches to total knee arthroplasty do not result in any improved early or late outcomes that would be considered clinically relevant. The use of peripatellar electrocautery was studied by Baliga et al.17, who included 185 patients having a total knee arthroplasty without patellar resurfacing. There is a theoretical possibility that peripatellar electrocautery would denervate the patella and reduce the incidence of postoperative pain in the anterior aspect of the knee. The study group of ninety-one patients received the treatment just before wound closure in this patient-blinded and assessor-blinded study. The authors followed patients for one year, making assessments with use of the Oxford Knee Score and a pain score for pain in the anterior aspect of the knee. The results indicated no significant differences between the groups with regard to any outcome measure, which led to the conclusion that peripatellar electrocautery does not reduce pain in the anterior aspect of the knee after total knee arthroplasty. Two studies specifically focused on the efficacy and utility of tourniquet use during total knee arthroplasty. Tai et al.18 conducted a prospective randomized controlled trial comparing thirty-six knees undergoing total knee arthroplasty performed with the use of a tourniquet to thirty-six knees undergoing total knee arthroplasty performed without use of a tourniquet. Tourniquets were set to a pressure of 100 mm Hg above the systolic pressure in the study group. Outcomes included blood loss, pain scores, thigh circumference, and levels of hemoglobin, hematocrit, serum creatine phosphokinase, myoglobin, C-reactive protein, and lactate dehydrogenase. The mean tourniquet time was fifty-three minutes, and the study group receiving tourniquet use demonstrated significant smaller decreases in postoperative hemoglobin (2.6 versus 3.7 g/dL, p < 0.001) and hematocrit (7.6% versus 10.4%, p = 0.001) on postoperative day 4, although there was no difference in the transfusion rate. Both the C-reactive protein and creatine phosphokinase were higher in the
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What’s New in Adult Reconstructive Knee Surgery nontourniquet group on postoperative day 2, demonstrating greater injury and inflammation without a tourniquet. On postoperative day 4, the study group receiving tourniquets did have a statistically significant higher pain level (p < 0.05), although the difference of 0.5 on the pain scale may not be clinically significant. These authors concluded that, due to the lack of clinically relevant differences between groups, they could not recommend for or against tourniquets. Olivecrona et al.19 also studied tourniquet use, specifically questioning the efficacy and utility of using the limb-occlusion-pressure (LOP) method compared with the routine method in which the tourniquet cuff pressure is based on the systolic blood pressure of the patient. They randomized 161 patients into each group, measuring postoperative pain, motion, and wound-related complications. Patients with a tourniquet pressure calculated by the LOP method more frequently had a cuff pressure set at
