Comparison of Revision Rates Due to Aseptic Loosening between High-Flex and Conventional Knee Prostheses

PURPOSE: The purpose was to evaluate and compare the revision rate due to aseptic loosening between a high-flex prosthesis and a conventional prosthesis. MATERIALS AND METHODS: Two thousand seventy-eight knees (1,377 patients) with at least 2 years of follow-up after total knee arthroplasty were reviewed. Two types of implants were selected (LPS-Flex and LPS, Zimmer) to compare revision and survival rates and sites of loosened prosthesis component. RESULTS: The revision rate of the LPS-Flex (4.9%) was significantly higher than that of the conventional prosthesis (0.6%) (p<0.001). The 5-, 10-, and 15-year survival rates were 98.9%, 96.2% and 92.0%, respectively, for the LPS-Flex and 99.8%, 98.5% and 93.5%, respectively, for the LPS. The survival rate of the high-flex prosthesis was significantly lower than that of the conventional prosthesis, especially in the mid-term period (range, 5 to 10 years; p=0.002). The loosening rate of the femoral component was significantly higher in the LPS-Flex prosthesis (p=0.001). CONCLUSIONS: The LPS-Flex had a higher revision rate due to aseptic loosening than the LPS prosthesis in the large population series with a long follow-up. The LPS-Flex should be used carefully considering the risk of femoral component aseptic loosening in the mid-term (range, 5 to 10 years) follow-up period after initial operation.

Estudio comparativo con prótesis total de rodilla de alta flexión: resultados funcionales y de rango de movimiento / Comparative study with high-flex total knee arthroplasty. Functional and range of motion. Results

Introducción: El objetivo de este trabajo comparativo fue analizar los resultados funcionales y el rango de movimiento de rodilla entre dos grupos de pacientes con artroplastia total de rodilla: uno utilizando prótesis de alta flexión y el otro con un diseño convencional. Materiales y Métodos: Setenta y cuatro pacientes fueron operados con artroplastia total de rodilla con prótesis de Zimmer NexGen®, EE.UU. Veintidós (grupo A) fueron tratados con diseño de alta flexión. Dos con artritis reumatoide fueron excluidos. Cuarenta y dos pacientes fueron tratados con una convencional, 21 de ellos fueron excluidos, por lo que el grupo B estaba conformado por 21 pacientes. La evaluación funcional se realizó con el Knee Society Score (KSS), el Western Ontario and McMaster Universities osteoathritis index y la escala analógica visual. Resultados: El promedio de flexión máxima preoperatoria fue de 99º en el grupo A y de 106º en el grupo B. En el posoperatorio, el promedio de flexión máxima del grupo A subió a 114º, con un aumento promedio de 15º y, en el grupo B, a 118º con una ganancia promedio de 12º. No hubo diferencias estadísticamente significativas (p <0,05). El puntaje KSS preoperatorio del grupo A fue de 36/48 y mejoró a 90/92. En el grupo B, fue de 46/49 y de 94/90 en el posoperatorio. Conclusión: Las evaluaciones clínicas funcionales y radiológicas son favorables en los dos diseños de prótesis evaluados. Este estudio muestra que no hay diferencias significativas entre el rango de movimiento de una prótesis de alta flexión y una prótesis convencional luego de un año de seguimiento...

Background: The purpose of this comparative study is to analyze functional results and the range of motion of the knee between two groups of patients with total knee arthroplasty using high-flex prosthesis (in one group) and with a conventional implant (in the other). Methods: Sixty-four patients were surgically treated with total knee arthroplasty with Zimmer NexGen®, USA. From this series, 22 patients (group A) were treated with high-flex design. Two cases with rheumatoid arthritis were excluded. Forty-two patients were treated with a conventional implant, 21 of them were excluded, and group B included 21 patients. Maximum flexion and extension were evaluated before and after surgery. Functional evaluation was performed with the Knee Society Score (KSS), the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), and an analogous visual scale. Results: The mean pre-surgical maximum flexion was 99° in group A and 106º in group B. Mean post-surgical maximum flexion in group A increased to 114º with an average increase of 15º and, in group B, to 118º with an average gain of 12º. There were no significant statistical differences (p <0.05). Pre-surgical KSS in group A was 36/48 and increased to 90/92. In group B, pre-surgical KSS was 46/49 and 94/90 after surgery. Conclusion: This study suggests that there are no significant differences in the range of motion, functional results, and radiographic evaluation in a high-flex total knee arthroplasty and a conventional design after one year of follow-up...

Outcomes of the Different Types of Total Knee Arthroplasty with the Identical Femoral Geometry

PURPOSE: There are controversies around the role of the posterior cruciate ligament and the effect of design modifications for high flexion in total knee arthroplasty (TKA). So, we compared the clinical outcomes of the cruciate retaining (CR), posterior stabilized (PS), and high flexion posterior stabilized (F-PS) designs in TKA with identical femoral geometry. MATERIALS AND METHODS: One hundred seventy nine knees with 3 different types of prostheses after a minimum 5-year follow-up were enrolled in this retrospective study: 45 with CR, 40 with PS and 94 with F-PS. The mean ages of these groups were 65.7, 67.2, and 67.5, and the mean durations of follow-up were 8.1, 8.0, and 6.8 years, respectively. We compared the range of motion, functional outcomes, and radiographic measurements at the 2-year follow-up and last follow-up. RESULTS: The maximal flexion angle was significantly lower in the CR group than the F-PS group at the 2-year follow-up. However, there was no significant difference at the last follow-up. Functional outcomes and survival rate of the three groups were similar at the last follow-up. CONCLUSIONS: Three different types of TKAs (CR, PS and F-PS) with identical femoral geometry showed similar mid-term outcomes with regard to the range of motion, functional outcomes and survival rate.

The Results of the P.F.C(R) Sigma(TM) RP-F Knee System in High Flex Rotating Platform Total Knee Arthroplasty -Comparison of Preoperative Range of Motion less than 90degrees Versus more than 90degrees-

PURPOSE: The purpose of this study was to evaluate the clinical and radiological results of using the P.F.C(R) Sigma(TM) RP-F Knee System for high flex rotating platform-flexion total knee arthroplasty in 2 groups of patients with a preoperative range of motion (ROM) less than 90 degrees or more than 90 degrees, respectively. MATERIALS AND METHODS: From January 2005 to November 2006, eighty-two patients received the P.F.C(R) Sigma(TM) RP-F Knee System for high flex rotating platform total knee arthroplasty, and they were evaluated for a minimum of 3 years. We subdivided the patients into two groups: the preoperative ROM less than 90degrees group and the more than 90degrees group. The clinical results were assessed using the ROM, the Hospital for Special Surgery (HSS) score, the Knee Society Score (KSS) and the Western Ontario and MacMaster Universities Osteoarthritis (WOMAC) score. The radiological results were evaluated using the tibio-femoral angle and the presence of loosening or osteolysis of the components. RESULTS: The ROM increased in the two groups at the last follow-up. The mean ROM range at the last follow up was significantly increased more in the less than 90degrees group compared to that in the more than 90o group. The HSS score, KSS, and WOMAC score significantly increased in the two groups, but there was no statistical difference between the two groups. The tibio-femoral angle improved in the two groups. There was no aseptic loosening or osteolysis. CONCLUSION: The postoperative clinical and radiological measures were significantly improved using the P.F.C(R) Sigma(TM) RP-F Knee System on the short term follow-up, and especially for the patients whose preoperative ROM was poor.

Functional Evaluation of High-Flex Total Knee Arthroplasty

PURPOSE: This study analyzed the functional result of High-Flex (HF) total knee arthroplasty (TKA) with focusing on the activities related to the Korean life style, and we identified the suitability of the presently used tools for performing functional evaluation. MATERIALS AND METHODS: We retrospectively analyzed 266 knees that underwent HF-TKAs with using a Scorpio-flex and the follow up period for all the knees was over 1 year. Functional evaluation was performed by questionnaire on activities, including cross-leg sitting, squatting, kneeling, standing from the floor, standing from a chair and ascending and descending stairs. The clinical evaluation included the Knee Society Knee Score (KSKS) & Function Score (KSFS), the WOMAC score and the patient's satisfaction score. The identification of suitable tools for the functional evaluation of high flexion activities was performed by statistical analysis. RESULTS: Deep flexion of the knees averaged 132.6degrees. Cross-leg sitting was possible for 90.6%, squatting for 32.3%, kneeling for 28.0%, standing from the floor for 66.9%, standing from a chair for 99.6%, ascending stairs for 96.2% and descending stairs for 90.6%. The WOMAC score and KSKS well differentiated the groups for the possibility of their activities, but the KSFS and patient's satisfaction did not differentiate between the groups for some activities. CONCLUSION: The functional evaluation after total knee arthroplasty with HF-TKA revealed good results on cross-leg sitting, standing from chair, ascending & descending stairs, but still poor results on squatting and kneeling. For the functional evaluation of HF-TKA, we believe that the WOMAC and KSKS are good evaluation tools. The KSFS and the patient's satisfaction need careful interpretation when using these for high flexion-related functional evaluation due to their lack of ability to differentiate between good and poor results by some activities.

A Comparison of the Functional Results of High-Flex Total Knee Arthroplasty: LPS-Flex vs. Scorpio-Flex TKA / 대한정형외과학회잡지

PURPOSE: This study compared the clinical and functional results of LPS-Flex with those of Scorpio-Flex TKA. MATERIALS AND METHODS: Fifty cases of High-Flex TKA (24 LPS-Flex and 26 Scorpio-Flex) were analyzed retrospectively. All the procedures were performed during the same period by the senior author and the patients were followed-up for more than 5 years. A functional evaluation was performed by a questionnaire on the high flexion-related activities, including cross-leg sitting, squatting, standing from the floor, standing from a chair and ascending and descending stairs. Each function was classified by the patients into five grades. The clinical evaluation included the range of motion, the Knee Society Knee Score and Function Score (KSKS & KSFS), the WOMAC score and the patient's satisfaction score. RESULTS: The functional evaluation showed a better result in the LPS-Flex group for the cross-leg sitting function (p=0.039) but there was no difference in the other functions. The clinical evaluation showed more flexion in the LPS-Flex group than that in the Scorpio-Flex group (p=0.044) but there were no difference in the KSKS, KSFS, WOMAC score and the patient's satisfaction score. CONCLUSION: LPS-Flex TKA showed better functional results for cross-leg sitting than did Scorpio-Flex TKA. This difference was attributed to the LPS-Flex group having more flexion than that of in the Scorpio-Flex group.

Three Years Follow-up Results of High-flex Total Knee Arthroplasty

PURPOSE: To evaluate the Three years clinical results of a total knee arthroplasty using the NexGen LPS-Flex fixed bearing system. MATERIALS AND METHODS: One hundred knees(65 patients) which used the LPS-Flex system for primary TKA and were followed up for a minimum Three years were evaluated. Evaluations included preoperative and postoperative range of motion(ROM), factors affecting the postoperative ROM that included age of the patient, the body mass index, the flexion contracture, degree of varus deformity, and Hospital for Special Surgery score. RESULTS: Knee ROM increased from preoperative 122.8 degrees to postoperative 130.5 degrees. The mean HSS score improved from preoperative 58.4 to postoperative 91.3. The femoral-tibial angle was changed from preoperative 6.4 degrees varus to a pos- toperative 5.5 degrees valgus. The most important factor that influenced the range of motion after an arthroplasty was the preoperative range of motion. One deep infection developed, but was cured with synovectomy and administration of antibiotics. CONCLUSION: Primary TKR with NexGen LPS-Flex system showed satisfactory early results including excellent ROM. We found that preoperative ROM had a significant effect on postoperative ROM.

A Comparative Study between High-Flex and Non High-Flex TotalKnee Arthroplasty / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to compare the clinical results of a high-flex design (Scorpioflex(R), Stryker) in total knee arthroplasty with those of a non-high-flex design (Scorpio(R) PS type, Stryker). MATERIALS AND METHODS: Fifty-two knees with at least 120 degrees of further flexion preoperatively underwent total knee arthroplasty. Of the 52 knees, there were 35 knees in the high-flex design (HF group) and 17 knees in the non high-flex design (non-HF group). The clinical results were evaluated by postoperative further flexion at 3 months, 6 months, 1 year, 2 years and 3 years, as well as by Delta flexion, which means postoperative flexion improvement. The Knee Society Score and X-rays were evaluated preoperatively and at the 3-year follow-up. RESULTS: The HF group showed significantly greater flexion than the non-HF group at 3 months postoperatively (p=0.000). The delta flexion was also greater in the HF group at 3 months postoperatively (p=0.000). The Knee Society Score and X-rays were similar in the two groups at the final follow-up (p>0.05). CONCLUSION: High-flex total knee arthroplasty appears to facilitate greater flexion in the first 3 months postoperatively, but there is no significant difference between both groups with regard to the range of motion, clinical and radiographic variables after 3 months.

Early Results of Primary High Flex Total Knee Arthroplasty

PURPOSE: We retrospectively evaluated the early results after total knee arthroplasty(TKA) using the Nexgen LPS-Flex fixed bearing knee system. MATERIALS AND METHODS: Ninety-five knees(71 patients) which used the LPS-Flex system for primary TKA and followed-up for a minimum 2 years were evaluated. Evaluation included preoperative and postoperative range of motion(ROM), factors affecting the postoperative ROM, Knee Society Score(KSS), knee function score, tibio-femoral angle and postoperative complications. RESULTS: Knee ROM was increased from preoperative 9.7 degrees - 123.6 degrees to postoperative 1.7 degrees - 130.7 degrees. The mean KSS and function score were improved from preoperative 53, 55 to postoperative 85 and 90 respectively. The tibio-femoral angle was changed from preoperative 5.5 degrees varus to a postoperative 5.3 degrees valgus. Two cases of early loosening of the femoral components occurred. One case underwent revision surgery while the other was closely followed up. There was no deep infection. CONCLUSION: Primary total knee arthroplasty with Nexgen LPS-flex system showed satisfactory early results including excellent ROM, except 2 cases of early loosening of femoral component. The etiology of this loosening requires further evaluation and study.