What's New in Adult Reconstructive Knee Surgery

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1 This is an enhance PDF from The Journal of Bone an Joint Surgery The PDF of the article you requeste follows this cover page. What's ew in Ault Reconstructive Knee Surgery Carl A. Deirmengian an Jess H. Lonner J Bone Joint Surg Am. 2008;90: oi: /jbjs.h This information is current as of December 1, 2008 Reprints an Permissions Publisher Information Click here to orer reprints or request permission to use material from this article, or locate the article citation on jbjs.org an click on the [Reprints an Permissions] link. The Journal of Bone an Joint Surgery 20 Pickering Street, eeham, MA

2 2556 COPYRIGHT Ó 2008 BY THE JOURAL OF BOE AD JOIT SURGERY, ICORPORATED Specialty Upate What s ew in Ault Reconstructive Knee Surgery By Carl A. Deirmengian, MD, an Jess H. Lonner, MD The purpose of this review is to iscuss the research presente on selecte topics in ault knee reconstruction uring the year The articles reference in this upate were selecte from both The Journal of Bone an Joint Surgery (American an British Volumes) an The Journal of Arthroplasty. Specialty Upate has been evelope in collaboration with the Council of Musculoskeletal Specialty Societies (COMSS) of the American Acaemy of Orthopaeic Surgeons. Epiemiology The total number of primary an revision total knee arthroplasties performe in the Unite States is projecte to increase ramatically uring the next several ecaes. Population growth, the increasing use of arthroplasty, an changing emographic patterns interact synergistically towar these projections. In aition to an overall increase in the total number of surgical proceures, it is expecte that the proportion of infections an revisions will increase. Publications focusing on future epiemiologic trens in knee arthroplasty are critical for riving future economic an public health policies. Kurtz et al. 1 projecte the expecte number of primary an revision hip an knee arthroplasty proceures in the Unite States from 2005 to They utilize ationwie Inpatient Sample ata for the years 1990 to 2003 as well as Unite States Census Bureau ata to formulate a moel for projecting the number of cases per year. The projection moel, taking both surgical prevalence an population ata into consieration, preicte a 673% increase in primary total knee arthroplasty to a total of 3.48 million proceures in Also projecte was a 601% increase in revision total knee arthroplasty to a total of 268,000 proceures in The authors suggeste that this massive increase in projecte knee arthroplasty proceures will require aitional surgeons, improve surgical efficiency, an increase economic resources. Kurtz et al. 2, in a separate stuy, quantifie the expecte future clinical an economic burens impose by infections an revisions in patients manage with arthroplasty. Again, the ationwie Inpatient Sample ata along with Unite States Census Bureau ata were use. The authors projecte that, from 2005 to 2030, the number of infections after revision total knee arthroplasty will increase from 6400 to 175,500. In comparison, the number of infections after revision total hip arthroplasty will increase from 3400 to 46,000. Aitionally, the authors projecte that the proportion of revision total knee arthroplasty performe specifically for the treatment of a eep infection will increase from 16.8% in 2005 to 65.5% in The economic buren resulting from these projections is a 450% increase in hospital charges an a 160% increase in surgical charges from 2005 to 2015 for revision total knee arthroplasty. Petterson et al. 3 stuie the impact of osteoarthritis on male an female caniates for knee arthroplasty. A variety of strength an function scores, incluing the Short Form-36 an Knee Outcome Survey scores, were use to compare healthy patients of both sexes as well as arthroplasty caniates of both sexes. The authors foun that, in aition to the expecte baseline ifferences between healthy patients of both sexes, there was an even larger ifference between arthroplasty caniates of both sexes. They conclue that women either are more aversely affecte by arthritis or are further along in the isease process before consiering arthroplasty. Consiering that the outcomes of total knee arthroplasty are relate to preoperative strength an function, the authors also suggeste that earlier surgical consieration may result in improve total knee arthroplasty outcomes for women. Disclosure: The authors i not receive any outsie funing or grants in support of their research for or preparation of this work. One or more of the authors or a member of his or her immeiate family receive, in any one year, payments or other benefits or a commitment or agreement to provie such benefits in excess of $10,000 (Zimmer) an of less than $10,000 (MAKO Surgical) from a commercial entity. Also, a commercial entity (Zimmer) pai or irecte in any one year, or agree to pay or irect, benefits in excess of $10,000 to a research fun, founation, ivision, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immeiate family, is affiliate or associate. J Bone Joint Surg Am. 2008;90: oi: /jbjs.h.01106

3 2557 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery Fehring et al. 4 stuie the epiemiology of obesity an its relationship to total knee arthroplasty. The authors retrospectively reviewe the boy mass inex for patients manage with total knee arthroplasty at their institution in 1990, 1995, 2000, an 2005 an compare these ata with general population ata from the Centers for Disease Control an Prevention. From 1990 to 2005, the proportion of obese patients unergoing total joint arthroplasty at their institution increase from 30% to 52%. In contrast, regional obesity rates uring the same time only increase from about 12% to about 22%. The authors also foun that, from 1990 to 2005, physician reimbursement for total knee arthroplasty ecrease 59% in inflation-ajuste ollars. Ientifying the relationship between obesity an the nee for total knee arthroplasty is an important factor when consiering public health policy an also may prove to be important in the evaluation of physician reimbursement. Unicompartmental Arthritis While unicompartmental knee arthroplasty offers both the possibility of a more rapi recovery than total knee arthroplasty oes as well as a conservative approach to the treatment of knee arthritis by virtue of the preservation of the cruciate ligaments an the maintenance of the non-arthritic compartments, universal enorsement of unicompartmental knee arthroplasty has been tempere by concerns about inferior long-term outcomes an the inherent ifficulties of performing the surgery accurately. Mullaji et al. 5 assesse functional recovery after 100 consecutive quariceps-sparing meial unicompartmental knee arthroplasty proceures. Inclusion criteria inclue isolate meial joint line tenerness, isolate meial compartment raiographic changes, an intact anterior cruciate ligament, a flexion eformity of <10, a correctable varus eformity of <15, an a boy mass inex of <30. The mean patient age was fifty-nine years, 31% of the patients were male, an the mean boy mass inex was 27. Patients younger than seventy years of age receive the Oxfor mobile-bearing unicompartmental knee arthroplasty (Biomet, Warsaw, Iniana), whereas oler patients receive the Preservation fixe-bearing unicompartmental knee arthroplasty (DePuy, Warsaw, Iniana). The average hospital stay was 2.1 ays, the average time to unassiste walking was 4.3 ays, an 95% of the patients coul ascen an escen stairs by the secon postoperative ay. At three months, the mean knee flexion was 139, with no flexion contractures of >5. The raiographic results were satisfactory, an there were no reporte woun-healing complications, thromboembolic events, or infections. Sah an Scott 6 reporte on the five-year results of fortyeight lateral unicompartmental knee arthroplasty proceures that ha been performe through a meial parapatellar approach by a single surgeon. Inclusion criteria inclue clinical an raiographic changes isolate to the lateral compartment, a flexion contracture of <10, an a valgus eformity of <10. Intraoperatively, the states of the patella an anterior cruciate ligament were evaluate for inclusion as well. A variety of lateral unicompartmental knee arthroplasty implants were use. The mean age was sixty-one years, an 80% of patients were female. At a mean of five years, there ha been no revisions or soft-tissue complications. All patients with osteoarthritis ha an excellent result. Knee an function scores were inferior when the preoperative etiology was posttraumatic arthritis as oppose to osteoarthritis. The authors emphasize the avantages of a meial parapatellar approach, incluing the ability to inspect the other joint compartments carefully. Although several stuies have emonstrate ten-year survival rates of >90% after meial unicompartmental knee arthroplasty, there remains a concern that certain esigns or populations may experience unacceptably high early failure rates. Mariani et al. 7 escribe their early results after thirtynine meial unicompartmental knee arthroplasties that ha been performe with use of a single esign (Preservation) from 2002 to At nine to twelve months, 38% of the arthroplasties ha faile as a result of femoral loosening. Failure i not correlate with any patient or surgery-relate factors. The authors hypothesize that, in flexion, ege loaing of the tibial component on the posterior conyle of the femoral component exerte an anterior force pushing the femoral component off of the femur as evience raiographically. Surgical Approaches Currently, there is mixe enthusiasm for minimally-invasive approaches an techniques, an there is general agreement that the size of the skin incision has little physiologic benefit on early or long-term outcomes after knee replacement. Kolisek et al. 8 conucte a prospective, ranomize, multicenter stuy of eighty total knee arthroplasties in which they compare the early results of stanar an mini-incision approaches. Patients were ivie into groups on the basis of the length of the skin incision, with patients with an incision of <13 cm being place in the minimal-incision group. The mivastus arthrotomy was use for the minimal-incision group, whereas a combination of approaches was use in the stanar-incision (control) group. There were no significant ifferences between groups in terms of early postoperative scores or bloo loss. However, there were four woun complications in the mini-incision group, compare with one in the stanar-incision group. It is clear from that stuy that the length of the skin incision has very little effect on postoperative recovery or bloo loss after total knee arthroplasty. The use of smaller incisions may actually compromise woun-healing. If there is a true benefit from minimally-invasive surgery, it likely lies more specifically in the eep issection of the knee. King et al. 9 conucte a retrospective review comparing stanar an quariceps-sparing total knee arthroplasty, with an emphasis on early outcomes an the surgical learning curve. The first 100 quariceps-sparing total knee arthroplasties were compare with forty-five stanar total knee arthroplasties

4 2558 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery that were performe by one high-volume surgeon. The surgeon i not evert the patella or islocate the tibia in the quariceps-sparing group. There were no ifferences between the groups in terms of the physical therapy protocol. The quariceps-sparing group ha a shortene mean hospital stay (2.8 compare with 3.7 ays), a higher proportion of ischarges to home (95% compare with 33%), less narcotic use, an a higher rate of walking without assistive evices at two an six weeks after surgery. The authors specifically state that no special efforts were mae for the postoperative care of the patients in the quariceps-sparing group. However, a learning curve was note with respect to tourniquet times an the accuracy of patellar resection, both of which improve through the course of the stuy. o complications or raiographic outliers were observe in the quariceps-sparing group. o ata were provie regaring intermeiate-term outcomes. Huang et al. 10 retrospectively stuie their early results after quariceps-sparing total knee arthroplasty an compare the results with those for a matche group of thirty-five patients who ha been manage with a stanar approach with a meial parapatellar arthrotomy. The greatest benefit was realize within the first two postoperative weeks, with the quariceps-sparing group having significantly improve quariceps strength an range of motion as well as less pain in comparison with the stanar total knee arthroplasty group. However, the quariceps-sparing group ha increase tourniquet times (mean, 122 compare with fifty-five minutes) an a higher number of raiographic outliers of implant alignment. The authors recommene the use of minimally invasive techniques to ecrease the morbiity after total knee arthroplasty but warne the surgeon of potential ifficulties associate with the learning curve. Tanavalee et al. 11 reporte on a prospective series of total knee arthroplasties in which the patients were ivie into three groups on the basis of the length of the meial arthrotomy proximal to the patella (1, 2, an 3 cm). All other patient care-relate factors, incluing anesthesia, physical therapy, an pain management protocols, were ientical among the groups. The authors foun that although range of motion an Knee Society scores were similar between the groups, patients who ha the longer arthrotomy (3 cm proximal to the patella) exhibite a significant early elay in time to walking an straight-leg raising. Walter et al. 12 performe a ranomize prospective stuy of 122 consecutive total knee arthroplasties to stuy the effect of patellar eversion on early function an ischarge. One surgeon use a mivastus arthrotomy, with or without patellar eversion, whereas another surgeon use either a mivastus or a parapatellar approach without patellar eversion. The only significant ifference between the groups was an earlier time to straight-leg raising for the patients manage with a mivastus approach without patellar eversion. The authors recommene avoiance of patellar eversion uring total knee arthroplasty. Flören et al. 13 also stuie the impact of patellar eversion in a retrospective review comparing minimally-invasive an stanar total knee arthroplasty. Seventy-four total knee arthroplasties that ha been performe through a mini-mivastus approach without patellar eversion were compare with fiftyseven total knee arthroplasties that ha been performe through a meial parapatellar approach with patellar eversion. The authors foun a lower rate of patellar tenon shortening an patella baja in the group that ha not unergone patellar eversion uring surgery. The increase rate of patella baja in the stanar-approach group (37% compare with 12%) was correlate with increase pain an ecrease flexion at one year after surgery. The ongoing ebate about the ifferences between the mivastus an subvastus surgical approaches has also le to a number of important stuies. Berth et al. 14 performe a ranomize prospective stuy of twenty patients unergoing bilateral simultaneous total knee arthroplasty, with the proceure on one sie being performe through a subvastus approach an the proceure on the contralateral sie being performe through a mivastus approach. At three an six months, there was no ifference in the maximal voluntary activation of the quariceps muscles between extremities. However, limbs in the subvastus group exhibite a higher level of pain until six months after surgery. Kelly et al. 15, in a prospective ranomize stuy of forty-two total knee arthroplasties, compare a stanar meial parapatellar approach with a vastus-splitting approach. At six months an five years, there were no functional ifferences between the groups, although there was a significant increase in the frequency of lateral releases in the stanar-approach group. Although electromyographic changes were foun in 43% of the knees in the vastus-splitting group, there were no functional consequences of these finings. Furthermore, these electromyographic changes were completely reverse in patients who ha ha a blunt vastus issection when stuie at five years. These stuies inicate that a mivastus or vastus-splitting approach oes not lea to a functionally important injury to the vastus meialis muscle. avigation an Robotics in Total Knee Arthroplasty The use of computer-assiste surgery in an effort to improve component an limb alignment continues to be of interest. Bauwens et al. 16 an Mason et al. 17 performe meta-analyses of navigate total knee arthroplasty an foun that the risk of limb malalignment was slightly higher in the conventional total knee arthroplasty group. However, the functional outcomes an complication rates were not clearly ifferent. Matziolis et al. 18 an Mullaji et al. 19 use prospectively ranomize methos to stuy the ifferences in limb an implant alignment between conventional an computer-assiste total knee arthroplasty; both groups of authors foun a higher rate of raiographic outliers in association with conventional total knee arthroplasty. The clinical consequences of these small

5 2559 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery ifferences are not clear. ovak et al. 20 stuie the costeffectiveness of computer-assiste surgery. On the basis of a review of the literature, they estimate that coronal malalignment of >3 results in an elevenfol increase in revision total knee arthroplasty at fifteen years. Assuming a 14% improvement in coronal alignment in association with computerassiste total knee arthroplasty, the authors conclue that it is possible that computer-assiste total knee arthroplasty is costeffective, epening on the exact variability in costs of the computer-assiste system an the variability in revision rates. Haier et al. 21 an Park an Lee 22 reporte on the concepts an techniques of robotic-assiste surgery. However, the fiel is in its infancy an, while the early reports are encouraging, aitional stuy is necessary to more clearly efine the clinical avantages an utility of robotic surgery. Perioperative Management The evolution of perioperative pain management an physical therapy protocols has ha a profoun impact on patient care after total knee arthroplasty. In a prospective ranomize stuy, Parvataneni et al. 23 stuie 131 patients unergoing total knee arthroplasty or total hip arthroplasty who were ranomize to receive either a multimoal pain protocol or a stanar protocol that involve patient-controlle analgesia. The multimoal pain protocol inclue preemptive analgesia; avoiance of high-ose, short-acting intravenous narcotics; an a periarticular injection of a combination of bupivacaine, morphine, epinephrine, methylprenisolone, an cefuroxime. The percentage of patients who were able to perform a straightleg raise on the first postoperative ay was significantly higher in the multimoal pain protocol group than in the stanar protocol group (63% compare with 21%). While the stuy group emonstrate less narcotic consumption an fewer sie effects as well as improve early functional recovery compare with the control group, the pain scores in the two groups were not significantly ifferent. Rama et al. 24 conucte a meta-analysis of eleven stuies in which the use of the tourniquet until woun closure was compare with tourniquet release before closure uring total knee arthroplasty. The authors foun that early tourniquet release increase the bloo loss by a mean of 229 ml an was associate with a greater ecrease in hemoglobin concentration after surgery. However, early tourniquet release also resulte in a significant ecrease in reoperations for the treatment of hematoma after total knee arthroplasty. Keating et al. 25 reporte the results of a prospective ranomize trial comparing postoperative vigor an hangrip strength in patients receiving epoetin alfa (PROCRIT; Ortho Biotech Proucts, Brigewater, ew Jersey) an those onating autologous bloo preoperatively. Multivariate analyses reveale an inepenent treatment effect in favor of epoetin alfa treatment for the overall change in vigor but not for hangrip strength. The patients who were manage with epoetin alfa also ha higher postoperative hemoglobin levels an a ecrease in the transfusion rate in comparison with those who preonate autologous bloo. Venous Thromboembolism Prophylaxis Prophylaxis against venous thromboembolism after total joint arthroplasty continues to be a source of contention, particularly as hospital an nationwie initiatives an protocols are being implemente. The most reference recommenation, by the American College of Chest Physicians, is thought by many joint arthroplasty surgeons to be base on oler ata that o not give ue emphasis to the complications that may result from anticoagulation. Given the recent avances in rapi recovery protocols, early ambulation, minimally-invasive techniques, an risk-ientification protocols, the selection of chemoprophylaxis after total knee arthroplasty is being reexamine. In May 2007, the Boar of Directors of the American Acaemy of Orthopaeic Surgeons approve a clinical guieline on the prevention of symptomatic pulmonary embolism in patients after joint arthroplasty. This guieline provies evience-base statements that hinge on the stratification of patients accoring to the risk of pulmonary embolism an the risk of major bleeing. A summary of the statements can be foun at Burnett et al. 26 prospectively evaluate the American College of Chest Physicians 1A protocol for Lovenox (enoxaparin) in a stuy of 290 consecutive patients manage with total hip arthroplasty or total knee arthroplasty. They foun that a ten-ay course of Lovenox resulte in major complications in 9% of the patients, incluing a 5.1% rate of prolonge hospitalization for woun rainage, a 4.7% rate of reamission, a 3.8% rate of symptomatic eep-vein thrombosis, an a 3.4% rate of reoperation for the treatment of woun complications. These values were highly unfavorable compare with the authors own historical controls who ha been manage with warfarin for anticoagulation. The authors iscontinue recruitment of aitional patients, terminate the stuy because of concerns regaring the complications, an consiere their outcomes to be a failure of the 1A protocol for Lovenox recommene by the American College of Chest Physicians. Dorr et al. 27 reporte the results of a retrospective stuy evaluating a multimoal approach to prophylaxis against thromboembolism in patients manage with hip an knee arthroplasty. Patient risk factors were use to stratify patients into treatment groups. Factors that esignate a patient as being at high risk inclue a history of a venous thromboembolic event that ha occurre within the previous five years, congestive heart failure that was classifie as Class II or III accoring to the system of the ew York Heart Association, atrial fibrillation with cariac isease an the use of Coumain (warfarin) preoperatively, recent surgery for the treatment of malignant isease or current ajuvant rug treatment, an thrombophilia (incluing factor-v Leien, prothrombin

6 2560 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery isorers, protein-c an S eficiency, antithrombin isorers, or hypercoagulability states). Of 970 consecutive patients, 856 were consiere low-risk an were manage with aspirin, ipyriamole, or clopiogrel bisulfate an limb-compression evices. One hunre an fourteen patients were classifie as high-risk an were manage with warfarin or low-molecularweight heparin an intermittent calf compression. All patients ha an ultrasoun Doppler stuy performe before ischarge an were mobilize within twenty-four hours after surgery. There were no significant ifferences between the high an low-risk groups with regar to pulmonary embolism or symptomatic eep-vein thrombosis. However, woun hematomas were only foun in patients receiving warfarin or lowmolecular-weight heparin. The authors recommene this multimoal approach as a metho for protecting patients from venous thromboembolism while minimizing the risks of anticoagulation. In the stuy by Brooks et al. 28, 224 patients who unerwent total knee arthroplasty with use of spinal anesthesia, intermittent compression stockings, an postoperative treatment with low-molecular-weight heparin were compare with 157 patients who unerwent a total knee arthroplasty with an inwelling epiural catheter for pain control, intermittent compression stockings, an no postoperative chemoprophylaxis. Monitoring at three ays with venous ultrasoun reveale no significant ifferences between the groups with regar to the prevalence of eep-vein thrombosis, with about 3% of the patients in both groups having a positive stuy emonstrating either proximal or istal thrombi. Pearse et al. 29 conucte a retrospective stuy to compare the rates of eepvein thrombosis in patients with an without early mobilization after total knee arthroplasty. All patients were manage with low-molecular-weight heparin an compression stockings. The prevalence of eep-vein thrombosis in patients manage with early mobilization (within twenty-four hours) was 1%, compare with 28% in patients who were mobilize on the secon postoperative ay. There was a thirtyfol ecrease in the risk of eep-vein thrombosis when patients were mobilize within the first twenty-four hours. This raises a question about whether early mobilization has a greater prophylactic effect against thromboembolism than chemoprophylaxis oes after total knee arthroplasty. Outcomes After Total Knee Arthroplasty Collier et al. 30 stuie polyethylene tibial bearings that ha been retrieve from 170 patients after uniconylar or total knee arthroplasty, with a focus on ientifying the main factors that contribute to wear after implantation. All tibial bearings ha been retrieve from patients who ha ha a preoperative varus eformity, an a large variety of implant polyethylene types were inclue. The authors foun that wear of the meial tibial bearing of both uniconylar an total knee replacements epene on the same three factors: patient age, the postoperative hip-knee-ankle angle, an the shelf age of the polyethylene utilize. That stuy emphasizes the importance of limb alignment an polyethylene shelf age to the rate of polyethylene wear after total knee arthroplasty. A number of stuies have compare the effect of ifferent implants on the outcome after total knee arthroplasty. Bertin 31 compare the clinical an raiographic outcomes of 225 cruciate-retaining total knee arthroplasties that ha been performe with use of either a stemme or pegge cemente tibial component. After as many as seven years, both implants exhibite excellent clinical an raiographic results, with 98% survival at seven years for both implants. Beaupré et al. 32,ina ranomize prospective stuy of eighty-one patients, compare cementless hyroxyapatite-coate tibial implants with cemente tibial implants. The only significant ifference foun in that stuy was slightly more pain in the cementless fixation group at six months that resolve at one year. o revisions were performe in either group. Duffy et al. 33 retrospectively evaluate the fifteen-year results of sixty-five hybri total knee arthroplasties that ha been performe with a cementless femoral component an a cemente tibial component. The authors foun a low femoral component survival rate of only 72% at fifteen years an reporte that they have abanone this technique in favor of other implantation methos. Mabry et al. 34, in a retrospective stuy of seventy knees that ha ha aseptic failure of a primary total knee arthroplasty, evaluate the ten-year results of revision total knee arthroplasty performe with use of moular fully cemente tibial an femoral stemme components. The five an ten-year survival rates, with further revision for aseptic failure as the en point, were 98% an 92%, respectively. Outcome stuies have also focuse on survivorship an results in various age groups. Duffy et al. 35 retrospectively reviewe fifty-two consecutive total knee arthroplasties that ha been performe with a cemente press-fit conylar esign in patients who were fifty-five years of age or younger. After an average uration of follow-up of twelve years, there ha been a total of eight revisions, yieling a preicte survival rate of 96% at ten years an 85% at fifteen years. Morgan et al. 36 stuie a consecutive cohort of eighty total knee arthroplasties that ha been performe with use of a cemente highlycongruent fully mobile prosthesis in patients with a mean age of 50.7 years. After a mean uration of follow-up of 7.3 years, there ha been no revisions for aseptic loosening an only one revision for polyethylene islocation. Alfonso et al. 37 retrospectively reviewe twenty-five patients with a minimum age of ninety years who ha unergone hip or knee replacement. Although there was an 8% rate of surgical complications an a 56% rate of meical complications, the patients experience pain relief an ha a slightly higher functional capacity an survival rate than i age-matche controls. The risks an benefits of components esigne with the intention of promoting or accommoating high flexion after total knee arthroplasty have been aresse. In the ranomize prospective stuy by Weeen an Schmit 38, a stanar

7 2561 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery posterior stabilize total knee arthroplasty was compare with a high-flexion posterior stabilize total knee arthroplasty. After an average uration of follow-up of one year, patients who ha receive the high-flexion esign achieve 13 more flexion in comparison with those who ha receive the stanar esign. Also, significantly more patients who ha receive the highflexion esign ha >135 of flexion. The authors conclue that these early results favor the use of femoral components with a high-flexion esign, although long-term follow-up is necessary to report on implant survival. Meneghini et al. 39 stuie the relationship between the egree of flexion an overall pain an function after total knee arthroplasty. In their retrospective review, they ivie 511 total knee arthroplasties into categories of flexion an mae correlations with function an pain scores. Patients with >125 of flexion ha no benefit in terms of overall knee function, but they i have a higher likelihoo of achieving optimal climbing function. The early benefits of high-flexion knee esigns may be more apparent as improve outcome tools are generate. Outcome stuies also have focuse on isease-specific patient groups in an effort to unerstan potential outcome effects of iffering emographic characteristics or isease states. Krushell an Fingeroth 40 conucte a retrospective stuy evaluating the five to fourteen-year results of thirty-nine total knee arthroplasties in morbily obese patients. Although the authors foun suboptimal alignment, an increase in the rate of minor woun complications, an a slightly higher rate of late revision, the overall complication rate was low in this morbily obese group. Aitionally, 85% of the patients were satisfie with the outcome. Joran et al. 41 retrospectively reviewe the results of seventeen total knee arthroplasties that ha been performe in limbs affecte by poliomyelitis, incluing eight arthroplasties that ha been performe with a posterior-stabilize esign, eight that ha been performe with a constraine conylar esign, an one that ha been performe with a hinge esign. Despite severe quariceps weakness, all patients exhibite a stable knee at an average of forty-two months of follow-up, with no signs of loosening. The authors conclue that espite softtissue an osseous abnormalities, improvements in terms of pain an function can be reliably achieve after total knee arthroplasty in patients with poliomyelitis, given that an implant of appropriate constraint is utilize. Pierson et al. 42, in an interesting retrospective stuy, evaluate the effect of overstuffing the patellofemoral compartment on outcomes after total knee arthroplasty. Preoperative an postoperative anterior patellar isplacement, anteroposterior femoral sizing, an combine anteroposterior patellofemoral sizing were measure in 830 knees that ha been followe for a minimum of two years after total knee arthroplasty. The authors foun that these parameters ha very little effect on the nee for lateral release uring total knee arthroplasty or on postoperative functional results an pain scores. The authors conclue that in their population of patients, patellofemoral overstuffing was not a cause of complications an shoul not be regare as a reason for revision in the absence of other ientifiable causes of failure. Woolson an Kang 43 compare the outcomes of total knee arthroplasties that ha been performe by a single attening surgeon in private practice with those that ha been performe by the same surgeon with the participation of a resient or a fellow on a teaching service. A retrospective review of 171 total knee arthroplasties reveale no ifference in the complication rates or outcomes between the two groups; however, total knee arthroplasties performe at the teaching service ha, on the average, a seven-minute longer tourniquet time. The authors conclue that well-supervise resients or fellows can participate in total knee arthroplasty without an increase risk of complications. Complications Just as surgical techniques an implants continue to be refine for improve function an survival after total knee arthroplasty, so have the unerstaning an treatment of complications avance. The iagnosis an treatment of infection continues to ominate the literature on complications after total knee arthroplasty. However, there have also been substantial refinements of our unerstaning of patellofemoral complications an stiffness after total knee arthroplasty. Parvizi et al. 44 retrospectively reviewe the local an systemic complications in 1636 patients within six weeks after primary unilateral hip or knee replacement. Among the 104 major, life-threatening complications, there were twenty-five pulmonary emboli, fourteen cases of acute renal failure, thirtythree cases of tachyarrhythmia, an ten cases of pulmonary eema or heart failure. inety percent of the complications occurre within four ays after surgery. Although age, obesity, an comorbiities were preictors of these complications, 58% of the patients who ha a major complication ha no preisposing factors. The authors cautione against early hospital ischarge after joint arthroplasty. Restrepo et al. 45 performe a meta-analysis of eighteen selecte publications involving 27,807 patients to analyze the relative risks of simultaneous bilateral total knee arthroplasty. The authors foun a higher prevalence of pulmonary embolism (os ratio, 1.8), cariac complications (os ratio, 2.5), an mortality (os ratio, 2.2) in association with simultaneous bilateral total knee arthroplasty. Stage bilateral total knee arthroplasty ha similar rates of complications when compare with unilateral total knee arthroplasty. It is not clear how the time between stage proceures relates to risk, nor is it clear which intraoperative factors contribute to the increase risk associate with simultaneous bilateral total knee arthroplasty. Fisher et al. 46 ientifie seventy-one knees (from a group of 1024 primary total knee arthroplasties) that were stiff or painful at one year after the inex proceure. This group was compare with a matche control group of 148 nonpainful knees with a well-functioning total knee replacement that ha

8 2562 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery ha a similar preoperative range of motion to ientify patientrelate factors that contribute to poor results after total knee arthroplasty. The authors ientifie female sex, a higher boy mass inex, previous knee surgery, isability status, iabetes mellitus, pulmonary isease, an epression as being significantly associate with the risk of having stiffness or pain at one year after surgery espite the presence of well-aligne, wellfixe components. The importance of patient-relate factors to the eventual outcome of total knee arthroplasty is clear, an these factors shoul influence preoperative counseling of patients awaiting total knee arthroplasty. Patel et al. 47 conucte a retrospective observational stuy of 1226 primary total knee arthroplasties to ientify the risk factors for prolonge woun rainage after surgery. After consiering pharmacological, surgical, an patient-relate risk factors, the authors reporte that increase rain output was the only ientifie risk factor for prolonge rainage an that obesity was the only ientifie risk factor for infection after total knee arthroplasty. Although infection continues to be one of the more serious complications after total knee arthroplasty, avances in the iagnosis an treatment of infection have le to improve care. Binelglass an Pellegrino 48 stuie the contribution of bloo cultures to the management of a patient who has a fever after primary joint arthroplasty. Of 240 patients who ha ha a total knee arthroplasty, forty ha a fever of >101 F (38.3 C) an were evaluate with bloo cultures. Only one patient ha a positive bloo culture, an this was eeme to be a falsepositive result without any resulting complication. The authors conclue that bloo cultures have limite value in the evaluation of postoperative fevers after total knee arthroplasty. Barrack et al. 49 retrospectively reviewe their experience with unexpecte positive intraoperative cultures after revision total knee arthroplasty. In a group of 692 consecutive revision total knee arthroplasties, forty-one patients ha unexpecte positive cultures. Twenty-nine of these patients ha only one positive culture in the absence of any other suspicion for infection, an twenty-four patients from that group were ischarge without any aitional treatment. At an average of four years, none of these twenty-four patients were foun to have an infection. The authors conclue that, in the absence of any suspicion for infection, a single positive intraoperative culture oes not manate aitional treatment after revision total knee arthroplasty. Della Valle et al. 50, in a stuy of ninety-four painful knees unergoing revision total knee arthroplasty, reporte on the use of a uniform protocol for the evaluation of infection. The protocol involve etermination of the erythrocyte seimentation rate (>30 mm/hr), etermination of the C-reactive protein level (>10 mg/l), perioperative synovial flui aspiration, intraoperative frozen-section analysis (>10 cells per fiel), an culture. Only one of the forty-one patients who were iagnose with infection ha a negative erythrocyte seimentation rate an a normal C-reactive protein level before revision. A synovial flui white bloo-cell count of >3000 ha an accuracy of 99% for the etection of infection. The authors recommene screening patients for infection on the basis of the preoperative erythrocyte seimentation rate an C-reactive protein level, followe by aspiration of the joint or intraoperative frozen-section analysis when the results of those two laboratory tests are elevate. Greianus et al. 51 prospectively evaluate the iagnostic utility of the erythrocyte seimentation rate an C-reactive protein level tests in the assessment of infection before revision total knee arthroplasty. Of 151 knees unergoing revision total knee arthroplasty, forty-five were iagnose with infection. Statistical analysis ientifie an erythrocyte seimentation rate of 22.5 mm/hr an a C-reactive protein level of 13.5 mg/l as the optimal positivity criterion. This provies a cutoff at which sensitivity an specificity are optimize, proucing the most accurate test results. The authors conclue that both the erythrocyte seimentation rate (sensitivity, 0.93; specificity, 0.83) an the C-reactive protein level (sensitivity, 0.91; specificity, 0.86) are excellent tests for the etection of infection in patients with pain at the site of a total knee arthroplasty. The authors provie a complete escription of test performance, incluing when the erythrocyte seimentation rate an C-reactive protein level are consiere in isolation or together. Mittal et al. 52 stuie the outcomes after two-stage reimplantation total knee arthroplasty when the original infecting organism was ientifie as methicillin-resistant staphylococcus. Thirty-seven patients were ientifie, each of whom ha ha a two-stage reimplantation with negative cultures at the time of reimplantation. ine patients ha a repeat infection, four with the same organism an five with a ifferent organism. The uration of intravenous antibiotics, a history of previous surgery, an comorbiities were not foun to be associate with reinfection. The authors recommene two-stage reimplantation even in the setting of antibioticresistant organisms. Freeman et al. 53 retrospectively ientifie seventy-six patients who ha unergone a two-stage reimplantation, with use of either static or articulating spacers, for the treatment of infection. The overall infection-eraication rate was 95% in the articulating spacer group an 92% in the static spacer group. There were no eventual ifferences in terms of pain scores after revision; however, patients manage with an articulating spacer ha a 58% rate of goo to excellent functional results, compare with a 36% rate in the static spacer group. The authors state that the use of articulating spacers may lea to improve functional results after two-stage reimplantation for the treatment of infection. A large number of stuies have focuse on the etiology an treatment of stiffness after total knee arthroplasty. The impact of flexion contractures was highlighte by Ritter et al. 54, who evaluate the relationship between loss of extension an outcome in a stuy of 5622 total knee arthroplasties. As expecte, preoperative flexion contracture an greater preoperative pain were risk factors for postoperative flexion contractures. Both hyperextension of >10 an flexion contractures were

9 2563 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery associate with the risk of a poor outcome. Keating et al. 55 retrospectively evaluate 113 knees with an average flexion of 70 that ha unergone manipulation with the patient uner anesthesia at an average of ten weeks after total knee arthroplasty. At five years after manipulation, the average improvement in flexion was 35, with no ifference between patients who ha unergone manipulation before an after twelve weeks. The authors recommene manipulation for the achievement of improvement in terms of pain an function in knees with 90 of flexion following total knee replacement. amba an Inacio 56 stuie 102 patients who ha unergone manipulation uner anesthesia within ninety ays after total knee arthroplasty an ninety-three patients who ha unergone manipulation more than ninety ays after total knee arthroplasty. Manipulation was foun to improve the range of motion an function in both groups, although greater gains were observe in the early-manipulation group. The authors recommene manipulation for the treatment of stiffness after total knee arthroplasty, even if it was elaye beyon ninety ays, although that may increase the risk of periprosthetic fracture or extensor mechanism rupture. Fehring et al. 57 retrospectively evaluate the outcomes after revision total knee arthroplasty for the treatment of painful flexion contractures of >15. Ten of the fourteen patients who were ientifie ha complete resolution of the flexion contracture after revision, with improvement in range of motion an pain scores. Evience-Base Orthopaeics The eitorial staff of The Journal reviewe a large number of recently publishe research stuies relate to the musculoskeletal system that receive a Level of Evience grae of I. Over 100 meical journals were reviewe to ientify these articles, all of which have high-quality stuy esign. In aition to articles alreay cite in this upate, seven aitional level-i articles were ientifie that were relevant to reconstructive knee surgery. A list of those articles is appene to this review following the stanar bibliography. We have provie a brief commentary about each of the articles to help to guie your further reaing, in an evience-base fashion, in this subspecialty area. Carl A. Deirmengian, MD Jess H. Lonner, MD Booth, Bartolozzi, Balerston Orthopaeics, Pennsylvania Hospital, 800 Spruce Street, Philaelphia, PA aress for J.H. Lonner: LonnerJ@pahosp.com References 1. Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary an revision hip an knee arthroplasty in the Unite States from 2005 to J Bone Joint Surg Am. 2007;89: Kurtz SM, Ong KL, Schmier J, Mowat F, Saleh K, Dybvik E, Kärrholm J, Garellick G, Havelin LI, Furnes O, Malchau H, Lau E. Future clinical an economic impact of revision total hip an knee arthroplasty. J Bone Joint Surg Am. 2007;89 Suppl 3: Petterson SC, Raisis L, Boenstab A, Snyer-Mackler L. Disease-specific gener ifferences among total knee arthroplasty caniates. J Bone Joint Surg Am. 2007;89: Fehring TK, Oum SM, Griffin WL, Mason JB, McCoy TH. The obesity epiemic: its effect on total joint arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2): Mullaji AB, Sharma A, Marawar S. Unicompartmental knee arthroplasty: functional recovery an raiographic results with a minimally invasive technique. J Arthroplasty. 2007;22(4 Suppl 1): Sah AP, Scott RD. Lateral unicompartmental knee arthroplasty through a meial approach. Stuy with an average five-year follow-up. J Bone Joint Surg Am. 2007;89: Mariani EM, Bourne MH, Jackson RT, Jackson ST, Jones P. Early failure of unicompartmental knee arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2): Kolisek FR, Bonutti PM, Hozack WJ, Purtill J, Sharkey PF, Zelicof SB, Raglan PS, Kester M, Mont MA, Rothman RH. Clinical experience using a minimally invasive surgical approach for total knee arthroplasty: early results of a prospective ranomize stuy compare to a stanar approach. J Arthroplasty. 2007;22: King J, Stamper DL, Schaa DC, Leopol SS. Minimally invasive total knee arthroplasty compare with traitional total knee arthroplasty. Assessment of the learning curve an the postoperative recuperative perio. J Bone Joint Surg Am. 2007;89: Huang HT, Su JY, Chang JK, Chen CH, Wang GJ. The early clinical outcome of minimally invasive quariceps-sparing total knee arthroplasty: report of a 2-year follow-up. J Arthroplasty. 2007;22: Tanavalee A, Thiengwittayaporn S, Itiravivong P. Progressive quariceps incision uring minimally invasive surgery for total knee arthroplasty: the effect on early postoperative ambulation. J Arthroplasty. 2007;22: Walter F, Haynes MB, Markel DC. A ranomize prospective stuy evaluating the effect of patellar eversion on the early functional outcomes in primary total knee arthroplasty. J Arthroplasty. 2007;22: Flören M, Davis J, Peterson MG, Laskin RS. A mini-mivastus capsular approach with patellar isplacement ecreases the prevalence of patella baja. J Arthroplasty. 2007;22(6 Suppl 2): Berth A, Urbach D, eumann W, Awiszus F. Strength an voluntary activation of quariceps femoris muscle in total knee arthroplasty with mivastus an subvastus approaches. J Arthroplasty. 2007;22: Kelly MJ, Rumi M, Kothari M, Parentis MA, Bailey KJ, Parrish WM, Pellegrini VD Jr. Comparison of the vastus-splitting an meian parapatellar approaches for primary total knee arthroplasty: a prospective, ranomize stuy. Surgical technique. J Bone Joint Surg Am. 2007;89 Suppl 2 Pt.1: Bauwens K, Matthes G, Wich M, Gebhar F, Hanson B, Ekkernkamp A, Stengel D. avigate total knee replacement. A meta-analysis. J Bone Joint Surg Am. 2007;89: Mason JB, Fehring TK, Estok R, Banel D, Fahrbach K. Meta-analysis of alignment outcomes in computer-assiste total knee arthroplasty surgery. J Arthroplasty. 2007;22: Matziolis G, Krocker D, Weiss U, Tohtz S, Perka C. A prospective, ranomize stuy of computer-assiste an conventional total knee arthroplasty. Threeimensional evaluation of implant alignment an rotation. J Bone Joint Surg Am. 2007;89: Mullaji A, Kanna R, Marawar S, Kohli A, Sharma A. Comparison of limb an component alignment using computer-assiste navigation versus image intensifierguie conventional total knee arthroplasty: a prospective, ranomize, singlesurgeon stuy of 467 knees. J Arthroplasty. 2007;22: ovak EJ, Silverstein MD, Bozic KJ. The cost-effectiveness of computer-assiste navigation in total knee arthroplasty. J Bone Joint Surg Am. 2007;89:

10 2564 W HAT S EW I A DULT R ECOSTRUCTIVE K EE S URGERY What s ew in Ault Reconstructive Knee Surgery 21. Haier H, Barrera OA, Garvin KL. Minimally invasive total knee arthroplasty surgery through navigate freehan bone cutting. J Arthroplasty. 2007;22: Park SE, Lee CT. Comparison of robotic-assiste an conventional manual implantation of a primary total knee arthroplasty. J Arthroplasty. 2007;22: Parvataneni HK, Shah VP, Howar H, Cole, Ranawat AS, Ranawat CS. Controlling pain after total hip an knee arthroplasty using a multimoal protocol with local periarticular injections: a prospective ranomize stuy. J Arthroplasty. 2007;22(6 Suppl 2): Rama KR, Apsingi S, Poovali S, Jetti A. Timing of tourniquet release in knee arthroplasty. Meta-analysis of ranomize, controlle trials. J Bone Joint Surg Am. 2007;89: Keating EM, Callaghan JJ, Ranawat AS, Bhirangi K, Ranawat CS. A ranomize, parallel-group, open-label trial of recombinant human erythropoietin vs preoperative autologous onation in primary total joint arthroplasty: effect on postoperative vigor an hangrip strength. J Arthroplasty. 2007;22: Burnett RS, Clohisy JC, Wright RW, McDonal DJ, Shively RA, Givens SA, Barrack RL. Failure of the American College of Chest Physicians-1A protocol for Lovenox in clinical outcomes for thromboembolic prophylaxis. J Arthroplasty. 2007;22: Dorr LD, Genelman V, Maheshwari AV, Boutary M, Wan Z, Long WT. Multimoal thromboprophylaxis for total hip an knee arthroplasty base on risk assessment. J Bone Joint Surg Am. 2007;89: Brooks PJ, Keramati M, Wickline A. Thromboembolism in patients unergoing total knee arthroplasty with epiural analgesia. J Arthroplasty. 2007;22: Pearse EO, Calwell BF, Lockwoo RJ, Hollar J. Early mobilisation after conventional knee replacement may reuce the risk of postoperative venous thromboembolism. J Bone Joint Surg Br. 2007;89: Collier MB, Engh CA Jr, McAuley JP, Engh GA. Factors associate with the loss of thickness of polyethylene tibial bearings after knee arthroplasty. J Bone Joint Surg Am. 2007;89: Bertin KC. Tibial component fixation in total knee arthroplasty: a comparison of pegge an stemme esigns. J Arthroplasty. 2007;22: Beaupré LA, al-yamani M, Huckell JR, Johnston DW. Hyroxyapatite-coate tibial implants compare with cemente tibial fixation in primary total knee arthroplasty. A ranomize trial of outcomes at five years. J Bone Joint Surg Am. 2007;89: Duffy GP, Murray BE, Trousale RR. Hybri total knee arthroplasty analysis of component failures at an average of 15 years. J Arthroplasty. 2007;22: Mabry TM, Vessely MB, Schleck CD, Harmsen WS, Berry DJ. Revision total knee arthroplasty with moular cemente stems: long-term follow-up. J Arthroplasty. 2007;22(6 Suppl 2): Duffy GP, Crower AR, Trousale RR, Berry DJ. Cemente total knee arthroplasty using a moern prosthesis in young patients with osteoarthritis. J Arthroplasty. 2007;22(6 Suppl 2): Morgan M, Brooks S, elson RA. Total knee arthroplasty in young active patients using a highly congruent fully mobile prosthesis. J Arthroplasty. 2007;22: Alfonso DT, Howell RD, Strauss EJ, Di Cesare PE. Total hip an knee arthroplasty in nonagenarians. J Arthroplasty. 2007;22: Weeen SH, Schmit R. A ranomize, prospective stuy of primary total knee components esigne for increase flexion. J Arthroplasty. 2007;22: Meneghini RM, Pierson JL, Bagsby D, Ziemba-Davis M, Beren ME, Ritter MA. Is there a functional benefit to obtaining high flexion after total knee arthroplasty? J Arthroplasty. 2007;22(6 Suppl 2): Krushell RJ, Fingeroth RJ. Primary total knee arthroplasty in morbily obese patients: a 5- to 14-year follow-up stuy. J Arthroplasty. 2007;22(6 Suppl 2): Joran L, Kligman M, Sculco TP. Total knee arthroplasty in patients with poliomyelitis. J Arthroplasty. 2007;22: Pierson JL, Ritter MA, Keating EM, Faris PM, Meing JB, Beren ME, Davis KE. The effect of stuffing the patellofemoral compartment on the outcome of total knee arthroplasty. J Bone Joint Surg Am. 2007;89: Woolson ST, Kang M. A comparison of the results of total hip an knee arthroplasty performe on a teaching service or a private practice service. J Bone Joint Surg Am. 2007;89: Parvizi J, Mui A, Purtill JJ, Sharkey PF, Hozack WJ, Rothman RH. Total joint arthroplasty: when o fatal or near-fatal complications occur? J Bone Joint Surg Am. 2007;89: Restrepo C, Parvizi J, Dietrich T, Einhorn TA. Safety of simultaneous bilateral total knee arthroplasty. A meta-analysis. J Bone Joint Surg Am. 2007;89: Fisher DA, Dierckman B, Watts MR, Davis K. Looks goo but feels ba: factors that contribute to poor results after total knee arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2): Patel VP, Walsh M, Sehgal B, Preston C, DeWal H, Di Cesare PE. Factors associate with prolonge woun rainage after primary total hip an knee arthroplasty. J Bone Joint Surg Am. 2007;89: Binelglass DF, Pellegrino J. The role of bloo cultures in the acute evaluation of postoperative fever in arthroplasty patients. J Arthroplasty. 2007;22: Barrack RL, Aggarwal A, Burnett RS, Clohisy JC, Ghanem E, Sharkey P, Parvizi J. The fate of the unexpecte positive intraoperative cultures after revision total knee arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2): Della Valle CJ, Sporer SM, Jacobs JJ, Berger RA, Rosenberg AG, Paprosky WG. Preoperative testing for sepsis before revision total knee arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2): Greianus V, Masri BA, Garbuz DS, Wilson SD, McAlinen MG, Xu M, Duncan CP. Use of erythrocyte seimentation rate an C-reactive protein level to iagnose infection before revision total knee arthroplasty. A prospective evaluation. J Bone Joint Surg Am. 2007;89: Mittal Y, Fehring TK, Hanssen A, Marculescu C, Oum SM, Osmon D. Twostage reimplantation for periprosthetic knee infection involving resistant organisms. J Bone Joint Surg Am. 2007;89: Freeman MG, Fehring TK, Oum SM, Fehring K, Griffin WL, Mason JB. Functional avantage of articulating versus static spacers in 2-stage revision for total knee arthroplasty infection. J Arthroplasty. 2007;22: Ritter MA, Lutgring JD, Davis KE, Beren ME, Pierson JL, Meneghini RM. The role of flexion contracture on outcomes in primary total knee arthroplasty. J Arthroplasty. 2007;22: Keating EM, Ritter MA, Harty LD, Haas G, Meing JB, Faris PM, Beren ME. Manipulation after total knee arthroplasty. J Bone Joint Surg Am. 2007;89: amba RS, Inacio M. Early an late manipulation improve flexion after total knee arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2): Fehring TK, Oum SM, Griffin WL, McCoy TH, Masonis JL. Surgical treatment of flexion contractures after total knee arthroplasty. J Arthroplasty. 2007;22(6 Suppl 2):62-6. Evience-Base Articles Relate to Reconstructive Knee Surgery Ensini A, Catani F, Learini A, Romagnoli M, Giannini S. Alignments an clinical results in conventional an navigate total knee arthroplasty. Clin Orthop Relat Res. 2007;457: This ranomize, prospective stuy evaluate the clinical an raiographic results of conventional an navigate total knee arthroplasty in 120 patients. Long-limb raiographs were use preoperatively to etermine the istal femoral resection angle in patients having conventional surgery. Postoperatively, long-limb raiographs an questionnaires were use to assess the results in both groups. The authors foun that navigate total knee arthroplasty resulte in more accurate resection planes, with most improvements amounting to a few egrees. Aitionally, navigate total knee arthroplasty reuce the number of cases of limb alignment of >3 from neutral (prevalence, 20% among patients manage with conventional total knee arthroplasty, as compare with 1.7% among patients manage with navigate total knee arthroplasty). At twenty-eight months of follow-up, there were no ifferences in clinical scores between patients manage with navigate an conventional total knee arthroplasty. However, given recent ata as reporte by Collier et al. 30, it is theoretically possible that improvements in limb alignment will result in long-term improvement in polyethylene wear an possibly loosening.