ABSTRACT
Objective Aiming at solving the problems of pain on the anteromedial tibia, tibial component loosening and osteoarthritis progression after unicompartmental knee arthroplasty (UKA), the influence of different geometric shapes of tibial component pegs on stress distributions in tibia was analyzed by finite element method. Methods The finite element models with UKA were established and validated. Geometric shapes of tibial component were designed. Under the same loading condition, the tibial components with double-peg, single-keel, double-keel and cross-star were studied for finite element analysis and compared with intact model, so as to evaluate the influence of tibial component with different shapes on stresses of cortical bone in anteromedial tibia, cancellous bone under tibial component and cartilage in contralateral tibia. Results Compared with the intact model, the peak stress of cortical bone in anteromedial tibia with double-peg, single-keel, double-keel and cross-star tibial components increased by 56.1%, 55.9%, 54.5% and 68-4%, respectively. The peak stress of cancellous bone under tibial component with single-keel and double-keels decreased by 8.1% and 15.6% respectively, while the peak stress of cancellous bone under tibial component with double-peg and cross-star increased by 67-9% and 121-5%, which were higher than the fatigue yield stress of cancellous bone. The peak stress of cartilage in contralateral tibia with double-peg, single-keel, double-keel and cross-star tibial components decreased by 42.1%, 26.6%, 24.2% and 28.5%, respectively. ConclusionsThe load distribution of the medial and lateral tibia changed after UKA operation, and a greater load was observed on the replacement side. Single-keel and double-keel tibial components were more effective in reducing stresses on cortical bone in anteromedial tibia and cancellous bone, while the stress distribution in tibia with single-keel tibial component was closer to that of the intact tibia. The research findings can provide theoretical references for designing single-keel tibial component of unicompartmental knee prosthesis which conforms to better mechanical properties of the knee joint.
ABSTRACT
Resumen: Se presenta el caso de una paciente de 94 años de edad, la cual fue intervenida hace 14 años de reemplazo articular de rodilla derecha por gonartrosis; actualmente con gonalgia y datos de inestabilidad. En las radiografías se aprecian signos de desgaste del polietileno y no se observan datos de aflojamiento en los componentes metálicos. El modelo implantado de polietileno ya no se fabrica en la actualidad y los componentes metálicos de la prótesis no presentan aflojamiento, por lo que se decide el cementado de un inserto de polietileno similar a las características previas para que se adapte al componente tibial. A dos años de evolución la paciente se reporta asintomática, con buena funcionabilidad y sin signos radiológicos de desgaste. Sólo se ha encontrado un caso clínico similar en Madrid con resultados igualmente satisfactorios, por lo que creemos que ésta puede ser una solución a un problema que se presenta cada vez más con mayor frecuencia en la práctica quirúrgica y que originalmente sólo se había descrito en revisiones de prótesis de cadera.
Abstract: We present the case of a 94 years- old patient, which was operated 14 years ago of a right total knee replacement for osteoarthritis, actually she suffers of pain and instability; her X ray shown polyethylene wear without loosening of the metal components. The polyethylene insert is not manufactured anymore so we decided cement a new polyethylene insert on the native tibial baseplate. The two years follow up show us a patient asymptomatic, good function and no radiolucencies on the tibial component. We only found a similar case report in Madrid and we believed that this decision, taken from total hip revisions, will succeed.
Subject(s)
Humans , Female , Arthroplasty, Replacement, Knee , Polyethylene , Knee Prosthesis , Osteoarthritis/surgery , Prosthesis Design , Reoperation , Bone Cements , Prosthesis Failure , Treatment OutcomeABSTRACT
PURPOSE: To evaluate the minimum 5-year mid-term clinical and radiological results of minimally invasive surgery total knee arthroplasty (MIS-TKA) using a mini-keel modular tibia component. MATERIALS AND METHODS: We retrospectively evaluated 254 patients (361 cases) who underwent MIS-TKA between 2005 and 2006. The latest clinical and radiological assessments were done in 168 cases that had been followed on an outpatient basis for more than 5 postoperative years. Clinical results were assessed using the Hospital for Special Surgery (HSS) score and Knee Society score. Radiological evaluation included measurements of knee alignment. RESULTS: The average postoperative knee range of motion and HSS score were 134.3degrees+/-12.4degrees and 92.7degrees+/-7.0degrees, respectively. The average postoperative femorotibial angle and tibial component alignment angle were 5.2degrees+/-1.7degrees valgus and 90.2degrees+/-1.6degrees, respectively. The average tibial component posterior inclination was 4.8degrees+/-2.1degrees. The percentage of cases with tibial component alignment angle of 90degrees+/-3degrees was 96.1%, and that with the femorotibial angle of 6degrees+/-3degrees valgus was 94.0%. Radiolucent lines were observed in 20 cases (12.0%): around the femur, tibia, and patella in 14 cases, 10 cases, and 1 case, respectively. However, they were less than 2 mm and non-progressive in all cases. The survival rate was 99.4% and there was no implant-related revision. CONCLUSIONS: MIS-TKA using a mini-keel modular tibial plate showed satisfactory results, a high survival rate, and excellent clinical and radiological results in the mid-term follow-up.
Subject(s)
Humans , Arthroplasty , Femur , Follow-Up Studies , Knee , Outpatients , Patella , Range of Motion, Articular , Retrospective Studies , Minimally Invasive Surgical Procedures , Survival Rate , TibiaABSTRACT
Objective To compare the difference between a vertical line (AA) drawn to the line connecting the inner edge of the patellar tendon with the mid-point of the ending point in the posterior cruciate ligament, tibial posterior condylar line (PC), tibial plateau anterior line (AC), the maximal mediolateral distance (MMLD) and a vertical line (BB) drawn to aligning the mid-point of ending point in the posterior cruciate ligament with the medial 1 / 3 of the patellar tendon relative to the surigical transepicondylar axis (STEA) by MRI, and to explore a reliable reference to determine tibial component rotation in total knee arthroplasty , and whether it will change in knees with varus deformity. Methods Thirty healthy volunteers (Group1) and thirty osteoarthritis patients (Group2) were enrolled in this study. The angles were measured among the five tibial rotation axes and STEA after MRI. Results The angles were (-1.48 ± 2.38)°, (6.16 ± 4.53)°, (6.45 ± 5.24)° ,(5.08 ± 4.99)° and (3.24 ± 2.68)° respectively in group 1 and (-1.88 ± 2.21)°, (-3.13 ± 4.66)°, (11.13 ± 5.72)°, (4.11 ± 4.15)° and (5.12 ± 4.87)° respectively in group 2. The angle between AA and STEA was not affected by varus deformity (P > 0.05), but the others were (P < 0.05). Conclusion The angle between AA and STEA is the smallest which is used to determine tibial component rotation in knees with varus deformity is the most reliable one.
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To evaluate the effect of tibial cut with posterior slope in total knee arthroplasty(TKA) surgery on the flexion of the knee, 41 knees(32 patients) with varying degree of the posterior slope were retrospectively reviewed at more than 1 year after operation. Does sloping the tibial cut iurface rnore posteriorly promote increasing of maximal flexion of the knee by elimination of excessive tenaion of the posterior cruciate liga ment The degree of the posterior slope was radiographically measured, awi the change of the degree of the maximal flexion between preoperative and postoperative period was clinimlly measured with a goniometer at the latest follow up more than 1 year after operation. Comparison of the results demonstrated significantly larger degree of rqaximal flexion for the knees that had tibial cut with the degree of the posterior slope, 5 degrees or rnore (p<0.05). We concluded that 5 degrees or more posterior slope in proxirnal tibial cut is one of the important fact()r which could achieve increased flexion of the knee after TKA operation.
Subject(s)
Arthroplasty , Follow-Up Studies , Knee Joint , Knee , Postoperative Period , Retrospective StudiesABSTRACT
In shape and dimensions, the tibial plateaus are asymmetric with the larger medial tibial plateau and both have a posterior inclination with respect to the shaft of the tibia. Maximizing tibial coverage is an impotant consideration in total knee arthroplasty to provide stahility and load transfer and to improve long-term survival rate of the implants. Most tihial tray designs are symmetric, but several asymmetric designs are available. We evaluated the proximal tibial resection surface during total knee aithroplasty to delineate the tibial plateaus in korean. After tihial bone cut during 100 TKA procedures, the outline of tibial resection suiface was traced and rotational axis of true tibial component was marked intraoperatively. A line was drawn at the maximal anteroposterior (AP) diameter of lateral tibial condyle with parallel to rotational axis of component, and then a transverse axis was drawn at the midpoint of maximal AP diameter of 1ateral tibial condyle. Anteroposterior 10, 20, 30., 40% and midpoint from the media1 and lateral peripheries were calculated manually. The average AP medial 10, 20, 30 and 40% dimensions were 34.7, 43.8, 48.0 and 43.2mm, respectively. The average AP lateral 10, 20, 30 and 40% dimensions were 30.2, 38.4, 42.0 and 40.9mm, respectively. The ratio of medial/lateral AP dimensions 10, 20, 30 and 40% from periphery were 116.9, 114.7, 114.5 and 106.4%, respectively. From these data, we know the asymmetry of the proxirnal tibia1 plateaus in korean. We hope that rnore data will be ohtained in multicenter studies and it will help us to select tibia1 tray and to design the tibial component in korean. But, more accurate standard measures will he need to minimize an error of measurements.
Subject(s)
Arthroplasty , Axis, Cervical Vertebra , Hope , Knee , Survival Rate , TibiaABSTRACT
Fifty four consecutive total knee arthroplasties were reviewed to compare the accuracy of extramedullary versus intramedullary tibial resection guides. An extramedullary guide ( Group I ) was used in 25 cases and an intramedullary guide ( Group 2 ) was used in 29 cases. Group 1 system included the LCS knee system and Group 2 system included the Whiteside Ortholoc Advantim total condylar knee system. Preoperatively, the two groups were similar, with no statistical significant differences observed in diagnosis, alignment, and patient age. Postoperative tibial component alignment angles were similar in both group (Group 1, 0.8degrees varus; Group 2, 1.1degrees varus ). In group 1, 84% of tibial components were aligned within 2degrees of the 90degrees goal and in group 2, 83% of tibial components were aligned within the same range ( p > 0.05 ). In all cases, an intramedullary guide was used to prepare the distal femur. In femorotibial angles, with group 1 averaging 4.2degrees valgus versus 4.7degrees valgus in group 2 (p > 0.05). If the optimal femorotibial angle was defined by the range from 5+/-2, it was achieved in 76% in Group 1 and 72% in Group 2 ( p > 0.05 ). This study demonstrates no significant differences between the extramedullary and intramedullary group not only in optimal tibial component alignment angle but also in optimal femorotibial angle. This means that each system is satisfactory for the tibial side, but it is more important for the surgeon to appreciate that the indications, potential limitations and sources of errors are unique to each system and to decide which system to use according to the particular case in question.