Posterior Shift of Contact Point between Femoral Component and Polyethylene in the LCS Rotating Platform Implant under Weight Bearing Condition

PURPOSE: To analyze the contact mechanics of the femoral component and polyethylene of the Low Contact Stress rotating platform (LCS-RP) in nonweight bearing and weight bearing conditions using full flexion lateral radiographs. MATERIALS AND METHODS: From May 2009 to December 2013, 58 knees in 41 patients diagnosed with osteoarthritis and treated with total knee arthroplasty (TKA) were included in this study. TKA was performed using an LCS-RP knee prosthesis. Full flexion lateral radiographs in both weight bearing and nonweight bearing condition were taken at least one month postoperatively (average, 28.8 months). Translation of femoral component was determined by the contact point between the femoral component and polyethylene. Maximum flexion was measured as the angle between the lines drawn at the midpoint of the femur and tibia. RESULTS: Posterior shift of the contact point in LCS-RP TKA was observed under weight bearing condition, which resulted in deeper flexion compared to LCS-RP TKA under nonweight bearing condition. CONCLUSIONS: In the LCS-RP TKA, the contact point between the femoral component and polyethylene moved posteriorly under weight bearing condition, and the joint was more congruent and maximum flexion increased with weight bearing.

CLINICAL OBSERVATION OF ROTATING-PLATFORM PROSTHESIS FOR VALGUS KNEE DEFORMITY / 中国修复重建外科杂志

OBJECTIVE: To investigate the effectiveness of rotating-platform prosthesis for valgus knee deformity in total knee arthroplasty (TKA). METHODS: A retrospective analysis was made on the clinical date of 25 cases (28 knees) of valgus deformity undergoing primary TKA by using Gemini MK II rotating-platform prosthesis. There were 6 males (7 knees) and 19 females (21 knees), aged from 47 to 82 years, with an average age of 64.8 years. The unilateral knee was involved in 22 cases and the bilateral knees in 3 cases. The causes included osteoarthritis in 20 cases (22 knees), rheumatoid arthritis in 4 cases (5 knees), and traumatic arthritis in 1 case (1 knee). The disease duration was 2-22 years (mean, 10.4 years). The main clinical symptoms were arthralgia combined with limited movement. According to the Keblish grade, there were 13 knees of mild deformity, 11 knees of moderate deformity, and 4 knees of severe deformity. RESULTS: All incisions healed by first intension. No complications of infection, cutaneous necrosis, deep venous thrombosis, and pulmonary embolism occurred. The postoperative follow-up duration was 12-60 months (mean, 25.4 months). Medial instability and palsies of nervus peroneus communis occurred in 1 and 2 cases respectively, and all were cured after symptomatic treatment. No patellar and polysthylene insert dislocation, prosthetic loosening or infection was observed. The Hospital for Special Surgery (HSS) score, femoral tibial angle, maximun flexion and extension angles, knee range of motion, and patellar score were significantly improved at last follow-up when compared with preoperative ones (P<0.01). CONCLUSIONS: The rotating-platform prosthesis for valgus deformity can obtain satisfactory effectiveness, but it requires precise soft tissue balancing technology, and the long-term effectiveness remains further observation.

Observation on early clinical efficacy of fixed platform and rotating platform in knee prosthesis arthroplasty for osteoarthritis of the knee / 中国基层医药

Objective To observe the early clinical efficacy of PFC fixed platform and RP rotating platform prosthesis two kinds of artificial knee replacement system for the treatment of knee osteoarthritis.Methods 39 cases (39 knees)with knee osteoarthritis were treated with total knee arthroplasty(TKA).According to intraoperative use of different types of prosthesis,the cases were divided into two groups:fixed platforms group 16 cases and rotating platform group 23 cases.The wound healing,patients with gait and knee activity after operation were observed.Results Three cases took place postoperative deep vein thrombosis,after conservative treatment,the symptoms improved and discharged,two cases of postoperative wound fat liquefaction,by dressing wound healing,time stitches discharged.3 to 12 months follow-up visit(average 10 months),all patients could walk uptight without noticeable limp.Last follow-up group,fixed platforms,rotating platform group Knee Score (HSS) and knee activity (ROM) were (83.17 ± 7.12),(81.32 ± 5.39) points and (109.73 ± 6.35) °,(103.12 ± 4.28) °,compared with the preoperative differencewasstatisticallysignificant (AgroupHSS:t =22.10,ROM:t =9.21 ; BgroupHSS:t =30.69,ROM:t =9.54,all P ＜ 0.01),but the difference between groups was not statistically significant(HSS:t =0.88,ROM:t =3.63,all P ＞ 0.05).Conclusion Using PFC and RP prosthesis after total knee replacement system in early has a good effect,both of which improve joint function early with no significant difference,but long-term effects need further observation.

Comparison of the Clinical Outcomes after Total Knee Arthroplasty with the LCS Rotating Platform Mobile Bearing Knee System and the PFC Sigma RP-F Mobile Bearing Knee System

BACKGROUND: We compared clinical outcomes after total knee arthroplasty with the Low Contact Stress (LCS) rotating platform mobile bearing knee system and the Press Fit Condylar Sigma rotating platform high flexion (PFC Sigma RP-F) mobile bearing knee system. METHODS: Fifty cases of total knee arthroplasty were performed with the PFC Sigma RP-F mobile bearing knee system and sixty-one cases were performed with the LCS mobile bearing total knee arthroplasty. The average duration of follow-up was 2.9 years. RESULTS: The mean Hospital for Special Surgery (HSS) knee score was 62.1 (range, 52 to 75) in the LCS group and 61.9 (range, 50 to 74) in the Sigma RP-F group preoperatively, and 90.1 (range, 84 to 100) in the LCS group and 89.8 (range, 83 to 100) in the Sigma RP-F group at the final follow-up. The mean preoperative flexion contracture was 6.7degrees (range, 0degrees to 10degrees) in the LCS group and 9.3degrees (range, 0degrees to 15degrees) in the Sigma RP-F group preoperatively. The mean range of motion was 124.6degrees (range, 105degrees to 150degrees) in the LCS group and 126.1degrees (range, 104degrees to 145degrees) in the Sigma RP-F group at the final follow-up. CONCLUSIONS: After a minimum duration of follow-up of two years, we found no significant differences between the two groups with regard to the range of knee motion or the clinical or radiographic results.

Bilateral Total Knee Arthroplasty using the Fixed Bearing Platform and the Rotating Platform in the Same Patient

PURPOSE: We wanted to evaluate the clinical and radiological results after total knee arthoplasty using the Press Fit Condylar (PFC) Sigma fixed bearing platform knee and the rotating platform knee in the same patient. MATERIALS AND METHODS: We enrolled 44 patients who had undergone bilateral total knee arthroplasties due to osteoarthritis of both knees from November 2001 to December 2004, using the fixed bearing platform and the rotating platform, respectively. The mean age of the study group was 71.5 years (range: 65~85 years). The mean follow up period was 74.3 months (range: 62~86 months). The clinical results were evaluated according to the knee score, the functional score, the presence of flexion contracture, the range of motion and the complications, and the visual analog scale system was used for the patients' satisfaction. The radiological results using the American Knee Society criteria and the tibiofemoral angle were also evaluated. RESULTS: The average knee score improved from 36.5 to 87.3 in the fixed bearing group and from 38.8 to 87.9 in the rotating platform group, respectively. The average functional score improved from 28.4 to 83.5 in the fixed bearing group and from 32.6 to 85.8 in the rotating platform group, respectively. The average range of knee motion improved from 85.5degrees to 115.5degrees in the fixed bearing group and from 86.6degrees to 116.8degrees in the rotating platform group. The average tibiofemoral angle improved from varus 8.2degrees to valgus 5.5degrees in the fixed bearing group and from varus 7.1degrees to valgus 5.3degrees in the rotating platform group. We did not observe any clinically significant osteolysis or wear. However, there were 3 cases of instability out of the 13 cases in rotating platform group, and this was accompanied by varus deformities of over 15 degree and 6 cases of friction sound during walking. CONCLUSION: We could find no clinical and radiological differences between the fixed bearing platform and the rotating platform in this study. However, we should regard the fixed bearing prosthesis as a good option for the patients with severe varus deformities, with considering performing bulky soft tissue release for obtaining a balanced gap, for preventing spin-out and to correct deformity.

Total Knee Arthroplasty with Rotating Platform Low Contact Stress(R): Minimum 3-Year Follow-up Results / 대한정형외과학회잡지

PURPOSE: To retrospectively evaluate the clinical and radiology results of total knee arthroplasty using a rotating platform Low Contact Stress (LCS(R)) Complete(TM). MATERIALS AND METHODS: Of 63 patients (82 knees) who had undergone a total knee arthroplasty with a rotating platform LCS(R) Complete(TM) between Jan. 2001 and Dec. 2002, 61 patients (79 knees) were followed up for more than three years and evaluated retrospectively. The average follow-up period was 3.5 years and the diagnosis in all cases was degenerative osteoarthritis. The average age at the time of surgery was 67.4 years, and no patient underwent patella resurfacing. RESULTS: The average active range of motion increased from 118degrees (95degrees-134degrees) preoperatively to 123degrees (100degrees-140degrees) at the last follow up. The average flexion contracture improved from 15degrees (0degrees-30degrees) preoperatively to 2degrees (0degrees-10degrees) at the last follow up. The average HSS knee score also improved from preoperative 64 points to 90 points at the last follow up. The radiology evaluation revealed a radiolucency rate of 10% in the tibia anteroposterior view and 9% in the femur. The complications encountered were two cases of a polyethylene liner dislocation; one in whom an open reduction was performed, and the other in whom the liner had been exchanged. CONCLUSION: A follow-up of the rotating platform LCS(R) Complete(TM) of more than three years yielded overall satisfactory results in the range of motion and function. However, there should be some concern regarding the development of polyethylene liner dislocation.

Comparison of Posterior Cruciate Ligament Retentionversus Substitution in PFCSigma Rotating-Platform Total Knee Arthroplasty / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to assess the results of posterior cruciate ligament-retaining and posterior cruciate ligament-sacrificing total knee arthroplasty using PFC Sigma rotating-platform (RP). MATERIALS AND METHODS: The subjects for this study were 43 patients who had undergone total knee arthroplasties by means of PFC Sigma RPs from February 2002 to July 2002 and, thereafter, had been observed for a period of at least 36 months. Twenty-two of the patients were categorized to group I, which retained the posterior cruciate ligament and 21 to group II, which substituted for the ligament. All the patients were evaluated for pre- and post-operative ranges of motion, the Hospital for Special Surgery (HSS) knee rating system, and radiographic analysis. RESULTS: The average flexion contracture was 6.5degrees (+/-1.0o) in group I and 6.7degrees (+/-0.8degrees) in group II pre-operatively, and 1.1degrees (+/-0.3degrees) in group I and 0.9degrees (+/-0.2degrees) in group II at the last follow-up. The average active range of knee motion improved from 87.6degrees (+/-6.5degrees) in group I and 86.6degrees (+/-6.1degrees) in group II pre-operatively, to 123.0degrees (+/-7.8degrees) and 125.1degrees (+/-7.3degrees), respectively, at the last follow-up. The average HSS score improved from 41.1degrees (+/-7.1degrees) in group I and 40.3degrees (+/-5.3degrees) in group II pre- operatively, to 87.3degrees (+/-6.0degrees) and 88.9degrees (+/-4.9degrees), respectively, at the last follow-up. There was also improvement in the average tibio-femoral angle from 8.0degrees in varus to 5.7degrees in valgus in group I and from 10.9 in varus to 5.4degrees in valgus in group II. Radiolucent lines were observed in 4 cases from group I and in 1 case from the group II. No significant progressive periprosthetic osteolysis was observed in the follow-up radiographs of both groups. CONCLUSION: There were no clinical and radiographic differences between the posterior cruciate ligament-retention and ligament-substitution groups, which indicates the necessity for long-term observation.

Condylar Lift Off in Fixed and Mobile Bearing Total Knee Arthroplasty

PURPOSE: To compare the performance of a total knee arthroplasty with either a PFC Sigma fixed bearing or a rotating platform in the same patient. MATERIALS AND METHODS: 48 cases (24 patients) that received a PFC Sigma fixed bearing and a rotating platform in both knees, one in each knee. The knee score, functional score, activity level, radiologic analyses through fluoroscope , varus/valgus stress, and subjective satisfaction evaluation were performed at the last follow up in the same patient. RESULTS: There were no significant differences in the knee score, functional score, activity level, radiological findings through fluoroscope, and subjective satisfaction. In the varus/valgus stress views, 3 cases of lateral femoral condylar lift-off were observed in the fixed bearing type and 6 cases of lateral femoral condylar lift-off were observed in the rotating platform type. CONCLUSION: In cases of total knee arthroplasty with PFC Sigma fixed bearing and with rotating platform performed in the same patient, there were no significant differences in the clinical, radiological and subjective satisfaction. However, it is considered that the fixed bearing is more stable in terms of medial and lateral femoral condylar lift-off with varus and valgus stress than rotating platform. Therefore long term follow-up would be necessary.

Moderate to Severe Varus Deformity in Total Knee Arthroplasty: PFC Sigma Fixed Bearing Versus Rotating Platform / 대한정형외과학회잡지

PURPOSE: To compare the performance of a fixed bearing with a PFC Sigma with that of a rotating platform in a total knee arthroplasty performed on patients with a moderate to severe varus deformity. MATERIALS AND METHODS: Among the patients who had received a total knee arthroplasty with either a PFC sigma fixed bearing or a rotating platform between October 1998 to June 2002, 77 cases (53 patients) with a > 15degrees varus deformity were examined. The surgery time and the clinical ratings and the radiographic images for each patient were investigated. RESULTS: There were no significant differences in the knee score, functional score, activity level, or radiological findings. There were seven cases where friction sounds were produced from the insertions in the rotating platform whilst walking and there were three cases of lateral instability. CONCLUSION: The PFC sigma fixed bearing was more effective for stabilizing the knees with a moderate to severe varus deformity because the rotating platform had a friction sound from the insertions while walking and lateral instability.

The Short-term Results of PFC Sigma Rotating-Platform in Total Knee Arthroplasty

PURPOSE: To evaluate the short-term results of PFC Sigma Rotating-Platform in total knee arthroplasty. MATERIALS AND METHODS: From November 2001 to April 2002, 41 knees in 25 patients who had been followed up over 2 year after TKA with PFC Sigma Rotating-Platform were evaluated retrospectively. RESULTS: The average range of motion increased from 96.9 degree preoperatively to 122.3 degree at the last follow-up. The average preoperative knee score (44.2) and functional score (51.3) improved to 90.8 and 92.1 respectively. The average score of activity level by authors 'improved from 42 preoperatively to 87 post-operatively. The radiolucent lines around prosthesis were found in 12% at femur and in 24% at tibia. But, none showed any clinical significance. Complications were superficial infections in 3 knees. CONCLUSION: The short-term results of PFC Sigma Rotating-Platform TKA were satisfactory. Therefore, long term follow-up evaluation is necessary.

Results of a Mobile Bearing Total Knee Replacement: Comparison of Retention and Sacrifice of the Posterior Cruciate Ligament

PURPOSE: The purpose of this study was to compare the results of posterior cruciate ligament retention and sacrificed total knee arthroplasties with mobile bearing design. MATERIALS AND METHODS: Between January 1992 and October 1997, the study consisted of two types of low contact stress(LCS) implants: a meniscal bearing implant(Group I) that retained the posterior crucaiate ligament(n=31), and a rotating platform implant(Group II) requiring sacrifice of this ligament(n=25). All patients were evaluated with pre-and postoperative range of motion and HSS(Hospital for Special Surgery)knee rating system and radiographic analysis at least five years following the knee replacement. RESULTS: The average active range of knee motion was 4 degrees-113 degrees (Group I), 5 degrees-109 degrees (Group II) preoperatively and 0 degrees-127 degrees (Group I), 0 degrees-118 degrees (Group II) at the final follow-up evaluation. The average HSS score was 61.7(Group I), 56.0(Group II) preoperatively and 90.1(Group I), 88.2(Group II) at the final follow-up evaluation. In group I, one patellar revision for patellar polyethylene breakage and one meniscal bearing change for medial meniscal bearing wear had been performed. In group II, one revision for infection and one rotating platform change had been performed for posterior instability during flexion. we had no dislocation of mobile bearing prosthesis, but 2 cases was required reoperation because of one traumatic periprosthetic fracture(Group 1) and one post. instability(Group 2). There was no significant progressive periprosthetic osteolysis on last follow-up radiographs in both groups. CONCLUSION: After five to ten years of follow-up, we found no signigicant difference between group I and II. However, it might be that subjective symptom is excellent in group I and surgical technique remains an important element of success with mobile bearing implants regardless of posterior cruciate ligament.

Early Failure of Mobile Meniscal in LCS Total Knee Replacement Arthroplasty: A Case Assessment / 대한정형외과학회잡지

PURPOSE: The mobile bearing, low contact stress, total knee replacement arthroplasty has proven successful with a high long-term survival rate and a low complication rate. Over 1,200 LCS knee has been successful with 97% survival. MATERIALS AND METHODS: However, we found fifteen knees showing early failure of mobile meniscal bearings with fracture, dislocation, and early wear, in some cases within three years. This caused the knee to subluxate and the bearings to dislocate. All fifteen knees had good surgical results with high HSS scores, normal valgus alignment, adequate sizing of the implants, lack of changes in the prosthese/bone interface as evidenced by the x-rays, and good ligament balancing. RESULTS: The reasons of the failure were: 1. Proportionately overweight patients. 2. Probable poor polyethylene quality due to air gamma radiation sterilization of the implant. 3. Overuse by the patients, causing undue load on the polyethylene. All patients with meniscal bearing failure had undergone revision surgery with good surgical results. CONCLUSIONS: We feel this merits further study to determine the relationship between the load and size of polyethylene mass in the rate of wear. While there are studies in the importance of thickness in relation to wear, we found no study on the effect that load has on the mass of polyethylene. We recommend a larger polyethylene tibial implant and rotating platform prostheses be used for an overweight patient and/or patient with high level of activity, both of which forecast a high load on the implant.