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Paper #13 Effect of femoral component offset on polyethylene wear in total hip arthroplasty
Abstracts From the AAHKS Eighth Annual Meeting 247 PAPER #10 CLINICAL AND R A D I O G R A P H I C EVALUATION OF HARRIS-GALANTE ACETABULAR CUP: F O U R TO NINE YEAR RESULTS Manuel O. Soto-Ruiz, MD, Jose A. Rodriguez, MD, New York, NY, Chitranjan S. Ranawat, M D In this study we seek to evaluate the intermediate term outcome of the Harris-Galante Porous noncemented socket and with special attention to the fLxation, wear and osteolysis. A retrospective evaluation of the clinical and radiographic results of the HGP acetabular cups was performed. 112 patients with a total of 127 hips done between 1987 to 1990 were evaluated. There were 82 patients with 93 hips available for follow up, with a mean age of 58.2 years(range 19 to 76. The mean follow up for these patients was 87 months (range 48 to 113). The average pre-operative Harris Hip score was 38 (range 10 to 63), improving to a postoperative hip score of 93 ( range 46 to 100). There were a total of 7 revisions; 2 of them for recurrent dislocations; 1 loose cup was revised; 1 loose femoral stem with associated osteolvsis and 3 hips were revised due to periprosthetic osteolysis, with change of the cup liner and bone grafting of the lesions. All four hips revised for acetabular osteolysis had visible evidence of wear of the non articulating as well as the articulating sides of the polyethylene liner. Radiographic evaluation for the non-revised sockets demonstrated that 22 (24%) hips had periacetabular osteolysis, where 16 (17%) were adjacent to the screws. Twenty-two hips (23%) demonstrated osteolytic lesions around the femoral stems. Most of the lesions were in zone I and II. There were radiolucent lines around 28 cups (30%) and only in 5 femoral stems (4%). The wear measurements were performed usin~ the modified computer vector technique, obtaining a mean wear of 1.00 mm (range from 0.40 to 4.5 mm) and a mean wear rate of 0.16 ram/year ( range from 0.05 to 0.44 mm ). The Harris-Galante socket has maintained a low fixation failure rate at intermediate term. With increasing follow up, wear of the polyethylene and periprosthetic osteolysis is a growing concern.
PAPER #I 1 A COMPARISON OF HYLAMER AND E N D U R O N POLYETHYLENE LINERS USED IN PRIMARY TOTAL HIP ARTHROPLASTY Wayne G. Paproskv, MD, FACS, Paul Nourbash, MD, Paramjeet Gill, MD, Winfield, 11We observed radiographic evidence of early wear in an uncemented, solid metal backed, acerabular component, with an ultra high molecular weight polyethylene (UHMWPE) liner, Hvlamer (Depuy). This prompted us to review the clinical performance of this liner and to compare it to another (UHMWPE) liner, Enduron (Depuy), inserted in a similar group of patients. We retrospectively reviewed 116 patients, age less than 65, who underwent primary total hip arthroplasty with an uncemented femoral and a solid backed acetabular component. The Hylamer group had 51 • W " lth 54 hips " --pauents and an average age of 55, mean foIlow-up of 4.3 years. The Enduron group had 65 patients with 71 hips and an average age of 55, mean follow-up of 6.1 years. Each patien-t was reviewed clinically for subluxation a n d for failure defined as recurrent dislocation or revision of the acerabular component or liner. Radiographically, patients were evaluated for liner wear. In the Hvtamer group, 6 of 54 (11%) patients required revision of the liner. In Z2of 6 patients, this was secondary to subluxation and in 4 of 6 patients this was due to recurrent dislocation. Three of 54 (6%),
have had recurrent subluxations with no revision at this point. In all 9 of these cases, the subluxation and dislocations have been secondary to superior liner wear of > 2 mm. An additional 6 patients have had > 2 mm. of superior liner with no symptoms. In the Enduron group, one of 71 patients had had liner wear > 2 mm. and only one of 71 (1.4%) has required revision for recurrent dislocation. This one revision was secondary to component malposition and not liner wear. Hvlamer has a failure rate of 17% and an incidence of accelerated wear'of 27% as compared to Enduron with 0 and 1.4% respectively. We conclude that the in vivo performance of Hylamer is inferior to that of Enduron in an age matched group. We are now following the remainder of our Hylamer group closely to assess the long term results and are no longer using this liner.
PAPER #12 *THE EFFECT OF CUP DESIGN ON POLYETHYLENE WEAR: AN ANALYSIS OF TEMPORAL WEAR FOR FOUR DIFFERENT ACETABULAR CUP DESIGNS IMPLANTED AT ONE INSTITUTION Christi J. Sychterz, MSE, Alexandria, VA, C. Anderson Engh, Jr., MD, Anthony M. Yang, Charles A. Engh, MD Radiographic assessment of head penetration into the polyethylene (PE) liner is a combination of both "true wear" (the actual removal of PE particles) and a "bedding-in" process (all other processes, such as creep and settling-in of the liner, that contribute to the initial movement of the headinto the cup). This study uses multiple linear regression analysis to model penetration versus time data as a line, allowing us to separate true wear" from "bedding-in." A computerized radiographic method was used to analyze 1,539 annuM radiographs from 367 hips implanted from 1 to 10,5 years, Temporal head penetration for 3 different first-generation noncemented acerabular components (110 Arthropor cups; 156 Triloc cups; and 47 HG cups) was compared to that of a second-generation component (54 Duraloc cups). O f the 3 first-generation components, the HG cups performed best, having the lowest total head penetration over time. The Arthropor group had greater head penetration than the HG group due to a statistically higher true wear rate (0. 13 vs. 0.08 mm/yr.,p<0.05). The Triloc group had greater headpenetration than that of the HG group due to statistically greater bedding-in (0.35 vs. 0.21 mm, p<0.05). Although design modifications of the second-generation Duraloc cup (thicker polyethylene, improved locking mechanism) decreased average head penetration, the Duraloc group had a higher true wear rate (0.12 mm/yr.) than two of the first--generation components studied. Surprisin ly, the decrease in head penetration for the Duraloc group resulted ~r~m decreasing the bedding-in of the liner. These findings have implications for those surgeons trying to decrease long-term wear-related complications by switching to newer acerabular component designs. Although the second-generation cup we studied had less total head penetration than two of the first-generation cups, the newer cup did not have a lower true wear rate. Thus, we cannot expect fewer wear-related complications with this newer component than we had with the first-generation cups. Temporal observations of head penetration make it possible to differentiate true wear from the bedding-in process. Monitoring head penetration over time is essential to assessing the wear performance implant systems.
PAPER #13 *EFFECT OF FEMORAL C O M P O N E N T OFFSET O N POLYETHYLENE WEAR IN TOTAL HIP ARTHROPLASTY Durgadas Sakalkale, MD, Peter F. Sharkey, MD, Philadelphia, PA, William J. Hozack, MD, Richard H. Rothman, MD, PhD. Kenneth Eng
" Denotes that something Premnters are boldface
of value was received
Introduction: Lateralization of the femoral component offset and trochanter in total hip arthroplasw theoretically leads to decrease in joint reaction forces. This may resialt in decreased polyethyiene wear.
248
The Journal of Arthroplasty Vol. 14 No. 2 February 1999
The purpose of this paper is to study the effect of femoral component offset on polyethylene wear. Methods: Seventeen bilateral total hip arthroplasties performed sequentially in 17 patients were reviewed in order to compare side to side polyethylene wear. Identical implants were used on both sides with one exception. One hip was replaced with a femoral component having a standard offset whereas the other side was replaced with a lateral offset implant. The lateralized implant pmvided a mean 7.3 mm increase in offset. The mean period of foUow-up was 5.6 yrs. (2 - 1.0.2) on the side with a standard femoral implant and 5.5 yrs. (2 - 9.7) on the side with a lateralized femoral component. The only statistically different parameter between the sides was the femoral component offset. (p=0.0001). All other parameters affecting polyethylene wear, such as period of follow up (p=0.73), head size (f9=0), head type, cup size (p=0.68), cup inclination (p= 0.71), medialization of cup (p= 0.20) and patient related factors were similar on both sides. On the side with a standard femoral component, the mean actual prosthetic offset (determined by manufacturer's specifications) was 35.2 mm and the radiologic offset was 31.5 mm. On the side with a lateralized femoral component the actual prosthetic offset was 42.3 mm and the radiologic offset was 40.1 mm. The difference in offsets between the sides was statistically significant (p=0.0001). The mean preoperative radiologic femoral offset was 38.gmm.
Results: Regression analysis revealed that only femoral component offset affected linear wear'rate significantly. (p=0.0004). Tlqe effect of other parameters such as age, sex, weight, height, cup angle, cup size, head size and period of follow-up on polyethylene wear w-as statistically insignificant (p values 0.50, 0.09, 0.48, 0.70, 0.47, 0.18, 0.86 and 0.98 respectively). On the side with a standard femoral component, the linear wear rate was 0.21 mm/yr, while on the side with a lateralized femoral component, it was 0.10 mm/yr.(p=0.002). Discussion: Lareralization of the femoral component offset may lead to a reduction in joint reaction forces. In this series, the preoperative dimensions of the hip were more closely restored by a lateral offset implant. The clinical consequence of this increase in offset is a reduction in oolvethvlene wear. Other potential advantages of an increased offset inc]ud'e improved hip stability and enhanced abductor mechanics.
Results: In among group comparisons, the only difference in the demographics was found in the age and weight being less in Group 3. When the bilateral TKRs were examined as individual procedures (Groups 1 and 3), there was no difference in OR time, crystalloid fluids, or wound drain output when compared to Group 2. The length of stay was significantly shorter in Group 1. There were however differences in intraop BP and HR, which were higher in Group 1. There was no difference in O2 saturation during surgery. There was no difference in the preop Hct or platelet, however Group 1 had lower postop Hot. This resulted in greater transfusions. The recovery__room time was also significandy longer in Group 1. There was no difference in the preop or postop knee scores, nor was there any difference in the alignment and other radiographic measurements among the 3 groups at a minimum of 1-year follow-up. In regards to financial data, Group I was significantly less than group 2 in overall costs, specifically in OR, radiotog'y, therapy, anesthesia, and labs. There was no difference between Groups 1 and 3 however. The most striking findings were: 1) 97% of Group 1 patients required rehab unit stay, while 30% of Group 2 and 3 patients required such disposition; 2) 4 major complications occurred in Group 1:2 MIs (1 fatal), 1 CVA, and 1 complicated pneumonia, while none occurred in Groups 2 and 3.
Discussion and Conclusion: Our data demonstrated financial advantage in performing 1-stage bilateral TKRs. However, we found a high rate o f medical complications. Moreover, the overall costs may have been higher in Group 1 if the costs of extended care facilities were included. Our data did not demonstrate any financial advantage of Group I over Group 3. We no longer recommend 1-stage bilateral TKRs.
PAPER #15 *PATIENT SATISFACTION AND O U T C O M E FOLLOWING SEPTIC VERSUS ASEPTIC REVISION TOTAL KNEE ARTHROPLASTY
Robert L. Barrack, MD, New Orleans, LA, Gerard Engh, MD, Cecil Rorabeck, MD, Jaswin Sawhney, MD, Michael Woolfrey, MD PAPER # 14 ONE-STAGE BILATERAL TOTAL KNEE REPLACEMENTS: SAFETY, EFFICACY AND COST-EFFECTIVENESS. A COMPARATIVE STUDY TO TWO-STAGE BILATERAL AND UNILATERAL TKRS Michael H. Huo, MD, Houston, TA; Raphael Levin, MD. James E "Wenz, MD, Susan M. McGill, RN, Dennis W. Lennox, MD Introduction: TKRs are among the most efficacious, and frequendy performed elective orthopaedic procedures. These are also among the most costly. This study was undertaken to principally evaluate the cost-effectiveness of 1-stage bilateral TKRs (Group 1). Moreover, we also evaluated the safety, and clinical and radiographic outcome at short-term follow-up. Methods: Over a 20-monthperiod, 33 patients underwent 1-stage bilateral TKRs (66 knees) under the care of 2 surgeons. These represented 24% of all the TKRs done during this interval. These patients were matched to 33 patients who underwent unilateral TKRs (Group 2) in regards to demographics, implant design, anesthesia, & rehab protocol In addition, a third group of 12 patients (Group 3) who underwent 2-stage bilateral TKRs during this-interval were also selected for this comparative study. All the surgeries were done using identical techniques with posterior-stabilized designs inserted with cement. Antibiotic and DVT prophylaxis regimens were similar. Data were obtained for intraoperative hemodynamics, perioperative complications, disposition after discharge, hospital costs, clinical and radiographic evaluation using the criteria proposed by The Knee Society. Statistical significance was set at p< 0.05.
• Denotes that ~ t h t n g of vaiue was r ~ i v e d Presenters ate boldface
Introduction: The results of 2 stage exchange for treatment of the infected total knee arthroplastv (TKA) is reported as being approximately 90% successful in eradicating infection and returning an acceptable level of function and pain relief. The results in terms of patient satisfaction and clinical outcome have rarely, if ever, been reported compared to a control group of patients undergoing revision total knee for other reasons. The purpose of this study was to report the results in terms of patient satisfaction and objective clinical outcome following septic versus aseptic revision TKA. Methods: A consecutive series of revision knees performed at the 3 university affiliated centers by 3 surgeons was prospectively studied. The same implant was utilized in all cases. The evaluation included a Knee Society Clinical Score (KSCS), SF36, Satisfaction Survey and radiographs, preoperatively, at 6 and 12 months postoperatively and annually thereafter. Follow-up averaging 36 months (range 24-60) was obtained in 118 of 130 knees (91%~. Twenty-two knees were infected and all were treated with 2 stage exchange with an interval of 4 to 6 weeks utilizing an antibiotic impregnated spacer block and intravenous antibiotics. 96 knees were revised for reasons for other than infection including aseptic component loosening, progressive osteolysis, and component instability.
Results: Preoperatively patients with infection had a significantly decreased arc of motion compared to those without infection (79 ° versus 98 °, p<.01). There was a strong trend for the infected knees to have a lower preoperative KSCS than the noninfected knees, although this did not achieve statistical significance (76 ° versus 92 ° p=.11). Postoperatively patients with infection continued to have a significantly decreased range of motion (93 ° versus 105 °, p=.01). The postoperative KSCS was markedly lower in the septic versus aseptic revisions (115 versus 135, p=.02). Patients with infection had a significantly lower function score (44 versus 57, p=.03), with a higher degree of pain and stiffness and lower degree of ambulatory ability. A significantly higher percentage of patients stated that they were unable to return to normal activities of daily living following septic versus aseptic revision TKA (21% versus 7%, p<.05). In spite of the inferior functional result, patients expressed an equal degree of satisfaction with the results of their treatment in septic versus aseptic revision cases.
PAPER #I 1 A COMPARISON OF HYLAMER AND E N D U R O N POLYETHYLENE LINERS USED IN PRIMARY TOTAL HIP ARTHROPLASTY Wayne G. Paproskv, MD, FACS, Paul Nourbash, MD, Paramjeet Gill, MD, Winfield, 11We observed radiographic evidence of early wear in an uncemented, solid metal backed, acerabular component, with an ultra high molecular weight polyethylene (UHMWPE) liner, Hvlamer (Depuy). This prompted us to review the clinical performance of this liner and to compare it to another (UHMWPE) liner, Enduron (Depuy), inserted in a similar group of patients. We retrospectively reviewed 116 patients, age less than 65, who underwent primary total hip arthroplasty with an uncemented femoral and a solid backed acetabular component. The Hylamer group had 51 • W " lth 54 hips " --pauents and an average age of 55, mean foIlow-up of 4.3 years. The Enduron group had 65 patients with 71 hips and an average age of 55, mean follow-up of 6.1 years. Each patien-t was reviewed clinically for subluxation a n d for failure defined as recurrent dislocation or revision of the acerabular component or liner. Radiographically, patients were evaluated for liner wear. In the Hvtamer group, 6 of 54 (11%) patients required revision of the liner. In Z2of 6 patients, this was secondary to subluxation and in 4 of 6 patients this was due to recurrent dislocation. Three of 54 (6%),
have had recurrent subluxations with no revision at this point. In all 9 of these cases, the subluxation and dislocations have been secondary to superior liner wear of > 2 mm. An additional 6 patients have had > 2 mm. of superior liner with no symptoms. In the Enduron group, one of 71 patients had had liner wear > 2 mm. and only one of 71 (1.4%) has required revision for recurrent dislocation. This one revision was secondary to component malposition and not liner wear. Hvlamer has a failure rate of 17% and an incidence of accelerated wear'of 27% as compared to Enduron with 0 and 1.4% respectively. We conclude that the in vivo performance of Hylamer is inferior to that of Enduron in an age matched group. We are now following the remainder of our Hylamer group closely to assess the long term results and are no longer using this liner.
PAPER #12 *THE EFFECT OF CUP DESIGN ON POLYETHYLENE WEAR: AN ANALYSIS OF TEMPORAL WEAR FOR FOUR DIFFERENT ACETABULAR CUP DESIGNS IMPLANTED AT ONE INSTITUTION Christi J. Sychterz, MSE, Alexandria, VA, C. Anderson Engh, Jr., MD, Anthony M. Yang, Charles A. Engh, MD Radiographic assessment of head penetration into the polyethylene (PE) liner is a combination of both "true wear" (the actual removal of PE particles) and a "bedding-in" process (all other processes, such as creep and settling-in of the liner, that contribute to the initial movement of the headinto the cup). This study uses multiple linear regression analysis to model penetration versus time data as a line, allowing us to separate true wear" from "bedding-in." A computerized radiographic method was used to analyze 1,539 annuM radiographs from 367 hips implanted from 1 to 10,5 years, Temporal head penetration for 3 different first-generation noncemented acerabular components (110 Arthropor cups; 156 Triloc cups; and 47 HG cups) was compared to that of a second-generation component (54 Duraloc cups). O f the 3 first-generation components, the HG cups performed best, having the lowest total head penetration over time. The Arthropor group had greater head penetration than the HG group due to a statistically higher true wear rate (0. 13 vs. 0.08 mm/yr.,p<0.05). The Triloc group had greater headpenetration than that of the HG group due to statistically greater bedding-in (0.35 vs. 0.21 mm, p<0.05). Although design modifications of the second-generation Duraloc cup (thicker polyethylene, improved locking mechanism) decreased average head penetration, the Duraloc group had a higher true wear rate (0.12 mm/yr.) than two of the first--generation components studied. Surprisin ly, the decrease in head penetration for the Duraloc group resulted ~r~m decreasing the bedding-in of the liner. These findings have implications for those surgeons trying to decrease long-term wear-related complications by switching to newer acerabular component designs. Although the second-generation cup we studied had less total head penetration than two of the first-generation cups, the newer cup did not have a lower true wear rate. Thus, we cannot expect fewer wear-related complications with this newer component than we had with the first-generation cups. Temporal observations of head penetration make it possible to differentiate true wear from the bedding-in process. Monitoring head penetration over time is essential to assessing the wear performance implant systems.
PAPER #13 *EFFECT OF FEMORAL C O M P O N E N T OFFSET O N POLYETHYLENE WEAR IN TOTAL HIP ARTHROPLASTY Durgadas Sakalkale, MD, Peter F. Sharkey, MD, Philadelphia, PA, William J. Hozack, MD, Richard H. Rothman, MD, PhD. Kenneth Eng
" Denotes that something Premnters are boldface
of value was received
Introduction: Lateralization of the femoral component offset and trochanter in total hip arthroplasw theoretically leads to decrease in joint reaction forces. This may resialt in decreased polyethyiene wear.
248
The Journal of Arthroplasty Vol. 14 No. 2 February 1999
The purpose of this paper is to study the effect of femoral component offset on polyethylene wear. Methods: Seventeen bilateral total hip arthroplasties performed sequentially in 17 patients were reviewed in order to compare side to side polyethylene wear. Identical implants were used on both sides with one exception. One hip was replaced with a femoral component having a standard offset whereas the other side was replaced with a lateral offset implant. The lateralized implant pmvided a mean 7.3 mm increase in offset. The mean period of foUow-up was 5.6 yrs. (2 - 1.0.2) on the side with a standard femoral implant and 5.5 yrs. (2 - 9.7) on the side with a lateralized femoral component. The only statistically different parameter between the sides was the femoral component offset. (p=0.0001). All other parameters affecting polyethylene wear, such as period of follow up (p=0.73), head size (f9=0), head type, cup size (p=0.68), cup inclination (p= 0.71), medialization of cup (p= 0.20) and patient related factors were similar on both sides. On the side with a standard femoral component, the mean actual prosthetic offset (determined by manufacturer's specifications) was 35.2 mm and the radiologic offset was 31.5 mm. On the side with a lateralized femoral component the actual prosthetic offset was 42.3 mm and the radiologic offset was 40.1 mm. The difference in offsets between the sides was statistically significant (p=0.0001). The mean preoperative radiologic femoral offset was 38.gmm.
Results: Regression analysis revealed that only femoral component offset affected linear wear'rate significantly. (p=0.0004). Tlqe effect of other parameters such as age, sex, weight, height, cup angle, cup size, head size and period of follow-up on polyethylene wear w-as statistically insignificant (p values 0.50, 0.09, 0.48, 0.70, 0.47, 0.18, 0.86 and 0.98 respectively). On the side with a standard femoral component, the linear wear rate was 0.21 mm/yr, while on the side with a lateralized femoral component, it was 0.10 mm/yr.(p=0.002). Discussion: Lareralization of the femoral component offset may lead to a reduction in joint reaction forces. In this series, the preoperative dimensions of the hip were more closely restored by a lateral offset implant. The clinical consequence of this increase in offset is a reduction in oolvethvlene wear. Other potential advantages of an increased offset inc]ud'e improved hip stability and enhanced abductor mechanics.
Results: In among group comparisons, the only difference in the demographics was found in the age and weight being less in Group 3. When the bilateral TKRs were examined as individual procedures (Groups 1 and 3), there was no difference in OR time, crystalloid fluids, or wound drain output when compared to Group 2. The length of stay was significantly shorter in Group 1. There were however differences in intraop BP and HR, which were higher in Group 1. There was no difference in O2 saturation during surgery. There was no difference in the preop Hct or platelet, however Group 1 had lower postop Hot. This resulted in greater transfusions. The recovery__room time was also significandy longer in Group 1. There was no difference in the preop or postop knee scores, nor was there any difference in the alignment and other radiographic measurements among the 3 groups at a minimum of 1-year follow-up. In regards to financial data, Group I was significantly less than group 2 in overall costs, specifically in OR, radiotog'y, therapy, anesthesia, and labs. There was no difference between Groups 1 and 3 however. The most striking findings were: 1) 97% of Group 1 patients required rehab unit stay, while 30% of Group 2 and 3 patients required such disposition; 2) 4 major complications occurred in Group 1:2 MIs (1 fatal), 1 CVA, and 1 complicated pneumonia, while none occurred in Groups 2 and 3.
Discussion and Conclusion: Our data demonstrated financial advantage in performing 1-stage bilateral TKRs. However, we found a high rate o f medical complications. Moreover, the overall costs may have been higher in Group 1 if the costs of extended care facilities were included. Our data did not demonstrate any financial advantage of Group I over Group 3. We no longer recommend 1-stage bilateral TKRs.
PAPER #15 *PATIENT SATISFACTION AND O U T C O M E FOLLOWING SEPTIC VERSUS ASEPTIC REVISION TOTAL KNEE ARTHROPLASTY
Robert L. Barrack, MD, New Orleans, LA, Gerard Engh, MD, Cecil Rorabeck, MD, Jaswin Sawhney, MD, Michael Woolfrey, MD PAPER # 14 ONE-STAGE BILATERAL TOTAL KNEE REPLACEMENTS: SAFETY, EFFICACY AND COST-EFFECTIVENESS. A COMPARATIVE STUDY TO TWO-STAGE BILATERAL AND UNILATERAL TKRS Michael H. Huo, MD, Houston, TA; Raphael Levin, MD. James E "Wenz, MD, Susan M. McGill, RN, Dennis W. Lennox, MD Introduction: TKRs are among the most efficacious, and frequendy performed elective orthopaedic procedures. These are also among the most costly. This study was undertaken to principally evaluate the cost-effectiveness of 1-stage bilateral TKRs (Group 1). Moreover, we also evaluated the safety, and clinical and radiographic outcome at short-term follow-up. Methods: Over a 20-monthperiod, 33 patients underwent 1-stage bilateral TKRs (66 knees) under the care of 2 surgeons. These represented 24% of all the TKRs done during this interval. These patients were matched to 33 patients who underwent unilateral TKRs (Group 2) in regards to demographics, implant design, anesthesia, & rehab protocol In addition, a third group of 12 patients (Group 3) who underwent 2-stage bilateral TKRs during this-interval were also selected for this comparative study. All the surgeries were done using identical techniques with posterior-stabilized designs inserted with cement. Antibiotic and DVT prophylaxis regimens were similar. Data were obtained for intraoperative hemodynamics, perioperative complications, disposition after discharge, hospital costs, clinical and radiographic evaluation using the criteria proposed by The Knee Society. Statistical significance was set at p< 0.05.
• Denotes that ~ t h t n g of vaiue was r ~ i v e d Presenters ate boldface
Introduction: The results of 2 stage exchange for treatment of the infected total knee arthroplastv (TKA) is reported as being approximately 90% successful in eradicating infection and returning an acceptable level of function and pain relief. The results in terms of patient satisfaction and clinical outcome have rarely, if ever, been reported compared to a control group of patients undergoing revision total knee for other reasons. The purpose of this study was to report the results in terms of patient satisfaction and objective clinical outcome following septic versus aseptic revision TKA. Methods: A consecutive series of revision knees performed at the 3 university affiliated centers by 3 surgeons was prospectively studied. The same implant was utilized in all cases. The evaluation included a Knee Society Clinical Score (KSCS), SF36, Satisfaction Survey and radiographs, preoperatively, at 6 and 12 months postoperatively and annually thereafter. Follow-up averaging 36 months (range 24-60) was obtained in 118 of 130 knees (91%~. Twenty-two knees were infected and all were treated with 2 stage exchange with an interval of 4 to 6 weeks utilizing an antibiotic impregnated spacer block and intravenous antibiotics. 96 knees were revised for reasons for other than infection including aseptic component loosening, progressive osteolysis, and component instability.
Results: Preoperatively patients with infection had a significantly decreased arc of motion compared to those without infection (79 ° versus 98 °, p<.01). There was a strong trend for the infected knees to have a lower preoperative KSCS than the noninfected knees, although this did not achieve statistical significance (76 ° versus 92 ° p=.11). Postoperatively patients with infection continued to have a significantly decreased range of motion (93 ° versus 105 °, p=.01). The postoperative KSCS was markedly lower in the septic versus aseptic revisions (115 versus 135, p=.02). Patients with infection had a significantly lower function score (44 versus 57, p=.03), with a higher degree of pain and stiffness and lower degree of ambulatory ability. A significantly higher percentage of patients stated that they were unable to return to normal activities of daily living following septic versus aseptic revision TKA (21% versus 7%, p<.05). In spite of the inferior functional result, patients expressed an equal degree of satisfaction with the results of their treatment in septic versus aseptic revision cases.