PAPER #5

INHOSPITAL COMPLICATIONS AND MORTALITY OF PATIENTS UNDERGOINGPRIMARY UNILATERAL, BILATERAL, AND REVISION TOTAL KNEEARTHROPLASTY: A STUDY OF 4169489 HOSPITAL DISCHARGES IN THEUNITED STATES BETWEEN 1990 AND 2004Stavros Memtsoudis, MD, Alejandro Gonzalez Della Valle, MD, Melanie C. Besculides, MD,Licia Gaber, Thomas P. Sculco, MD

It has been suggested that patients undergoing bilateral total knee arthroplasty (BTKA) have a highercomplication rate and mortality than those undergoing a unilateral procedure (UTKA). We analyzednationally representative data to elucidate the demographics, comorbidities, hospital stay, inhospitalcomplications, and mortality of patients undergoing BTKA and compared them with those of patientsundergoing UTKA and revision TKA (RTKA).

Data in the National Hospital Discharge Survey on hospital discharges with procedure codes for BTKA,UTKA, and RTKA between 1990 and 2004 were analyzed. The demographics, comorbidities, inhospitalstay, complications, and mortality were studied.

We identified 4169489 discharges (153259 BTKAs, 3677161 UTKAs, and 339069 RTKAs). Patientsundergoing BTKAwere younger (1.5 years) and had a lower prevalence of comorbidities for hypertension(vs UTKA), diabetes, lung disease, and coronary artery disease (vs UTKA and RTKA). The length ofhospitalization was 5.8 days for BTKA, 5.28 for UTKA, and 5.41 for RTKA. Despite similar length ofhospitalization, the prevalence of procedure-related complications was higher for BTKA (14.17% ± 0.76[SE]) than for UTKA (9.01% ± 0.17) and RTKA (9.84% ± 0.57). Inhospital mortality was highest forBTKA patients (BTKA: 0.47% ± 0.15%; UTKA: 0.30% ± 0.03; RTKA: 0.27% ± 0.09).

Despite younger age and lower comorbidity burden, patients undergoing BTKA had an approximately1.6 times higher rate of procedure related complications and mortality compared with those undergoingUTKA. Outcomes for RTKA patients for most variables were similar to those for UTKA. In amultivariate regression analysis, BTKA, advanced age, and male sex were independent risk factors forcomplications and mortality after total knee arthroplasty.

doi:10.1016/j.arth.2008.01.221

PAPER #6

INHOSPITAL COMPLICATIONS AFTER TOTAL JOINT ARTHROPLASTYLuis Pulido, MD, Javad Parvizi, MD*, James J. Purtill, MD, Peter F. Sharkey, MD*,William J. Hozack, MD*, Richard H. Rothman, MD*

Total joint arthroplasty (TJA) is a safe and successful procedure. However, the medical communityneeds to be aware of the various types of complications in the early hospital setting associated withelective TJA. This study prospectively collected data on systemic and local in hospital complicationsafter 15383 TJA, which included 8230 total hip arthroplasties (6795 primary, 224 conversions and 1211revisions) and 7153 total knee arthroplasties (6500 primary and 653 revisions). The hospital course ofevery patient was followed up closely.

The circumstances leading to the complications and the details of the therapeutic intervention for eachcomplication were recorded. In general, the incidence of complications was higher after kneearthroplasty and revision surgery. Bilateral arthroplasties also presented with higher rate ofcomplications. There were 22 (0.16%) deaths, most of which occurred within 6 days after surgery.Four hundred eighty-six systemic major complications occurred in the cohort that included pulmonaryembolus (152), tachyarrhythmia (92), myocardial infarction (36), stroke (19), asystole (2), respiratoryfailure (14), aspiration pneumonitis (8), pneumothorax (2), systemic sepsis (7), gastrointestinal bleeding(3), small bowel obstruction (3), toxic megacolon (3), and acute renal failure (48). There were 109 majorlocal complications, including 16 vascular injuries, 29 peripheral nerve injuries, 25 periprostheticfractures, and 18 dislocations. Most of the local complications occurred within 4 days of index surgery.

Total joint arthroplasty despite its success can be associated with serious and life-threateningcomplications. This prospective study provides the baseline complications that can occur after electivejoint arthroplasty.

doi:10.1016/j.arth.2008.01.222

PAPER #7

MINIMAL INCISION SURGERY AS A RISK FACTOR FOR EARLY FAILURE OFTOTAL KNEE ARTHROPLASTYRobert Barrack, MD, C. Lowry Barnes, MD*, Derek Miller, DO, Stephen Burnett, MD,John Clohisy, MD*, William Maloney, MD*

Introduction: A study was undertaken to determine the current prevalence of revisions of total kneearthroplasty (TKA) after minimal incision surgery (MIS) and to compare revisions of MIS TKAprocedures to revisions of TKA performed after a standard surgical approach.

Materials and Methods: A consecutive series of revision TKA performed at 3 centers by 5 surgeonsover a 3-year period was reviewed. Revisions performed for infection, and re-revisions were excluded.Review of clinical and radiographic data determined incision type, sex, age, time to revision, andprimary diagnosis at time of revision.

Results: Two hundred thirty-six first-time revisions were performed, of which 43 (18.2%) had been MISTKA, and 193 (81.8%) had been standard TKA. Patients with MIS were younger (61.7 vs 66.2 years,P = .02). There was a higher percentage of women in the MIS group (73% vs 63%), although thisdifference was not significant (P N .2). Most striking was the difference in time to revision, which wassignificantly shorter for the MIS group (14.8 vs 80 months, P b .001). The MIS group was much morelikely to fail at less than 12 months (37% vs 5%, P b .001) and at less than 24 months (81% vs 22%,

P b .001). The MIS group showed a trend to having a higher incidence of loosening as the primarycause for failure (58% vs 44%, P b .1).

Conclusion: Minimal incision surgery TKA accounted for a substantial percentage of revision TKA inrecent years at these centers. The high prevalence of MIS failures occurring within 24 months isdisturbing and warrants further investigation.

doi:10.1016/j.arth.2008.01.223

PAPER #8

THE EFFECT OF HIGH-IMPACT SPORTS ON TOTAL KNEE ARTHROPLASTIESMichael A. Mont, MD*, David Marker, Slif Ulrich, MD, Thorsten Seyler, MD

Introduction: Orthopedic surgeons continue to discourage high-impact sports after total kneearthroplasty because of the theoretical risk of polyethylene wear. However, increasing numbers ofpatients are seeking an active lifestyle after surgery, and many are choosing to participate in high-impactsports. Although simulated laboratory conditions have shown high-impact loading can have adverseeffects on the durability of total knee arthroplasties, there are no known in vivo studies whichspecifically analyze conditions in patients participating in high-impact sports activity. The purpose of thepresent study was to analyze whether the clinical and radiographic results of total knee arthroplasties inpatients returning to demanding, high-impact sports activity after surgery differed from those of patientswho did not participate in these activities.

Methods: After using an objective activity questionnaire to collect information regarding sportsactivity and overall satisfaction, 21 patients (23 knees) were identified who participated in high-impactsports after total knee arthroplasty. There were 13 men and 8 women, with a mean age of 61 years andmean body mass index of 27.4. Each patient participated in 1 or more high-impact sports including:singles tennis (13), jogging (7), downhill skiing (2), racketball (2), squash (1), and basketball (1). Allpatients were evaluated clinically and radiographically at a mean 88-month follow-up, and resultswere compared with the overall cohort of 191 total knee arthroplasty patients who responded to theactivity questionnaire.

Results: The patients participating in high-impact sports demonstrated excellent clinical andradiographic outcomes. At the time of final follow-up, overall satisfaction was a mean of 9.3 points,and there were no complications requiring revision. The mean Knee Society objective and functionscores were 91.8 points and 95.6 points, respectively. These scores were similar to the overall group ofpatients who had mean scores of 95.5 points and 95.5 points. Radiolucencies were found in both cohortsof patients, but none were progressive.

Conclusion: High-impact activities are not appropriate for most patients after total knee arthroplasty.However, the results of the present study indicates that some patients participating in high-impact sports,such as jogging, downhill skiing, and singles tennis, can enjoy excellent clinical outcomes during thefirst 7 years after surgery. As increasing number of patients seek to return to sports after surgery, it isimportant that surgeons work closely with patients to provide individualized recommendations regardingsports activity.

doi:10.1016/j.arth.2008.01.224

PAPER #9

REPRODUCING THE MECHANICAL AXIS DID NOT IMPROVE THE 15-YEARSURVIVAL OF 398 MODERN TOTAL KNEE ARTHROPLASTYSebastien Parratte,MD, Robert T. Trousdale,MD, Daniel J. Berry,MD*,MarkW. Pagnano,MD*

Introduction: A fundamental premise of computer-assisted total knee arthroplasty (TKA) is thatcorrecting the mechanical axis will promote implant durability. Only 1 publication has correlatedpostoperative limb alignment assessed on full-length x-rays with survivorship, and those authors used aknee implant substantially different from modern designs. With substantial resources being devoted tocomputer-assisted TKA, we decided to review, in a large group with full-length radiographs, thefundamental premise that correction of the mechanical axis predicts long-term durability of modern TKA.

Materials and Methods: Between 1984 and 1989, 1 surgeon performed 398 primary cemented TKAswhere standardized pre- and postoperative full-length radiographs were done. Age was 76 ±10 years,and body mass index 30 ± 4 was kg/m

2. Failure was defined as aseptic loosening, implant revision,

or substantial wear. A multivariate model evaluated survivorship, mechanical alignment, and asso-ciated factors.

Result: Postoperative alignment in these 398 patients was 180.3 ± 3. In 105 knees, postoperativealignment deviated more than 3° from the mechanical axis (outliers). At 15 ± 4.7 years, survival torevision, aseptic loosening, or substantial wear was 94% for the group within 180 ± 3°. At the sameinterval, the survival for the 58 outliers was 96%.

Discussion: We were surprised by the finding that outliers had better 15-year survival. Althoughcomputer navigation improves the precision of TKA, this study suggests that the accuracy of TKA maynot be improved. To maximize both patient function and implant durability, more work must be done toclearly define the appropriate target for limb alignment in various patient groups after TKA.

doi:10.1016/j.arth.2008.01.225

PAPER #10

IMPLANT MIGRATION IN TOTAL KNEE ARTHROPLASTY IS RELATED TOBODY MASS INDEX AND TIBIAL COMPONENT SIZEMichael E. Berend, MD*, Merrill A. Ritter, MD*, Ken Davis, Hans Hyldahl, MD

316 The Journal of Arthroplasty Vol. 23 No. 2 February 2008