Stability and anchorage considerations for cementless tibial components

The purpose of this study was to investigate if the type of approach [medial parapatellar approach (MPA) versus lateral parapatellar approach with tibial tubercle osteotomy (LPA)] influences rotation of femoral and/or tibial component and leg axis in total knee arthroplasty (TKA). It was the hypothesis that MPA leads to an internally rotated tibial TKA component. This study included 200 consecutive patients in whom TKA was performed using either a parapatellar medial (n=162, MPA) or parapatellar lateral approach with tibial tubercle osteotomy (n=38, LPA). All patients underwent clinical follow-up, standardized radiographs and computed radiography (CT). TKA components' position and the whole leg axis were assessed on 3D reconstructed CT scans (sagittal, coronal and rotational). Mean values of TKA component position and the whole leg alignment of both groups were compared using a t test. The tibial component was graded as internally rotated (<3° of external rotation (ER)), neutral rotation (equal or between 3° and 6° of ER) and externally rotated (>6° ER). The femoral component was graded as internally rotated [>3° of internal rotation (IR)], neutral rotation (equal or between -3° IR and 3° of ER) and externally rotated (>3° ER). There was no significant difference in terms of whole leg axis after TKA between both groups (MPA: 0.2° valgus±3.4; LPA: 0.0° valgus±3.5). Means of tibial component rotation were 2.7° ER±6.1 (MPA) and 7.6° ER±5.4 (LPA). Patients of group LPA presented a significantly less internally rotated (LPA: 18.4%; MPA: 48.8%) and more externally rotated (LPA: 52.6%; MPA: 22.8%) tibial component (p<0.001). No significant differences were seen for the femoral component position, tibial valgus/varus and tibial slope. The type of approach (medial versus lateral) significantly influenced tibial TKA component rotation. It appears that a MPA tends to internally rotate the tibial TKA component and a LPA tends to externally rotate the tibial TKA. The anterior cortex should not be used as landmark for tibial TKA component placement when using the lateral approach with tibial tubercle osteotomy. Retrospective comparative study, Level III.

To Editor: A number of recent articles, including In Vivo Deterioration of Tibial Baseplate Locking Mechanisms in Contemporary Modular Total Knee Components (2001;83-A:1660-5), by Engh et al., and The Effectiveness of Isolated Tibial Insert Exchange in Revision Total Knee Arthroplasty (2002;84-A:64-8), by Babis et al., have discussed modularity of tibial components in total knee arthroplasty. Both of these studies mentioned the potential advantage of a reduction of implant inventory with use of modular components. We have not experienced these perceived benefits of modular tibial components in total knee arthroplasty. We currently have an inventory of both modular and nonmodular total knee arthroplasty systems. nonmodular system that we use is the AGC (Anatomic Graduated Components) Total Knee System (Biomet, Warsaw, Indiana). To have an adequate inventory for use in primary total knee arthroplasty, we maintain three patellar sizes; five tibial component sizes, each with seven corresponding polyethylene thicknesses; and five universal femoral components, which …

Analysis of the shape of the tibial tray in total knee arthroplasty using a three dimension finite element model

ObjectivesThe design of tibial trays for total knee arthroplasty (TKA) has been a topic of research for several decades. Although all-polyethylene trays were developed to address issues such as osteolysis and to enhance the longevity of the prosthesis, as well as knee range of motion, metal-backed designs have remained the most commonly used type of prosthesis. This meta-analysis aimed to compare the clinical, radiological, and survival outcomes of both designs.MethodsFive databases were searched from inception until October 1, 2020, for randomized controlled trials (RCTs) that compared the outcomes of all-polyethylene and metal-backed tibial components in TKA. The outcomes of interest included range of motion, knee society score, stairs climbing scores, radiostereographic analysis, survivorship and complication. This review was conducted in line with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Risk of bias was assessed using the Newcastle–Ottawa tool.ResultsA total of 14 RCTs with 1367 TKA were included with a mean age of – years and – years for all-polyethylene and metal-backed tibial components groups, respectively. All-polyethylene group demonstrated statistically significant differences in five-year survivorship (OR 0.27; 95% CI 0.10–0.75; p value 0.01) and stairs climbing score (OR − 2.07; 95% CI − 3.27–0.87; p value 0.0007) when compared to the metal-backed group. The metal-backed design was significantly more radiographically stable in anterior–posterior, varus–valgus, and internal–external rotations at the 2-year follow-up compared to all-polyethylene tibias (OR − 0.09; 95% CI − 0.16 to − 0.02; p value 0.02) as per the pooled radiostereographic analysis. However, ten-year survivorship (OR 0.92; 95% CI 0.53–1.60; p value 0.78), range of motion (OR − 0.57; 95% CI − 2.00–0.85, p value 0.43), knee society scores (OR 1.38; 95% CI − 0.47–3.23, p value 0.14), and complications (OR 0.83; 95% CI 0.5–1.39, p value 0.48) were comparable between both groups.ConclusionsWhile this meta-analysis suggests that all-polyethylene tibial components in total knee arthroplasty may offer advantages over metal-backed components in terms of five-year survivorship, and stairs climbing score, this finding should be considered in the context of potential confounding factors. Nonetheless, based on the results, the all-polyethylene implant should be considered a viable choice for primary knee replacement.Level of evidenceI.

The accuracy of computed tomography for determining femoral and tibial total knee arthroplasty component rotation

Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA. Radiostereometric analysis (RSA) data over a two-year period were available for 419 successful primary TKAs (267 cemented and 152 uncemented in 257 female and 162 male patients). Longitudinal analysis of data using marginal models was performed to examine the associations of patient factors (age, sex, BMI, smoking status) and implant factors (cemented or uncemented, the size of the implant) with maximum total point motion (MTPM) migration. Analyses were also performed on subgroups based on sex and fixation. In the overall group, only fixation was significantly associated with migration (p < 0.001). For uncemented tibial components in males, smoking was significantly associated with lower migration (p = 0.030) and BMI approached significance (p = 0.061). For females with uncemented components, smoking (p = 0.081) and age (p = 0.063) approached significance and were both associated with increased migration. The small number of self-reported smokers in this study warrants cautious interpretation and further investigation. For cemented components in females, larger sizes of tibial component were significantly associated with increased migration (p = 0.004). No factors were significant for cemented components in males. The migration of uncemented tibial components was more sensitive to patient factors than cemented implants. These differences were not consistent by sex, suggesting that it may be of value to evaluate female and male patients separately following TKA. Cite this article: Bone Joint J2022;104-B(4):444-451.

PurposeAnatomical rotational mismatch (ARM) refers to postoperative malrotation between the femur and tibia, and component rotational mismatch (CRM) refers to malrotation between the femoral and tibial components in total knee arthroplasty (TKA). This study aimed to quantify ARM and CRM and assess their individual and combined effects on postoperative outcomes.MethodsThis retrospective study analysed 224 knees that underwent primary TKA. Postoperative axial rotational angles between the femoral and tibial components (component rotational angle [CRA]) and between the femur and tibia (anatomical rotational angle [ARA]) were measured using computed tomography. Internal tibial or tibial component rotation relative to the femur or femoral component was assigned a positive value. Rotational mismatch was defined as CRA and ARA over ±10°. Clinical outcomes were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) 1 year postoperatively. Hierarchical cluster analysis categorised knees into two groups based on CRA and ARA (Groups 1 and 2).ResultsThe mean ± standard deviation (SD) postoperative ARA was 5.2° ± 5.3°, with ARM present in 16.1% of cases (36 knees). Knees with ARM showed significantly worse improvement in the KOOS pain subscale than those without ARM (p = 0.02). Postoperative CRA was 1.5° ± 4.5°, with CRM observed in 2.7% of cases (6 knees), but CRM alone did not significantly affect postoperative outcomes. Cluster analysis identified two groups (Group 1: 185 knees; Group 2: 39 knees), with Group 2 exhibiting greater CRAs and ARAs compared to Group 1 (both p < 0.01). Group 2 also had significantly worse KOOS pain and activities of daily living improvement relative to Group 1 (p < 0.01, 0.04).ConclusionsBoth CRM and ARM were observed following TKA. ARM negatively impacted postoperative outcomes, and the combined presence of CRM and ARM further worsened clinical results.Level of EvidenceLevel IV.

Based primarily on in vitro biomechanical studies, most total knee arthroplasty (TKA) manufacturers have abandoned the all-polyethylene tibial component (APT) in favor of the metal-backed tibial component (MBT). There is little clinical evidence to support this decision. A retrospective review of cemented TKA using the total condylar prosthesis was performed. One hundred eighteen patients with 131 TKAs were evaluated. Sixty-two of these knee prostheses had tibial components made entirely of polyethylene while 69 had the MBT. There were 13 cases of bilateral TKA in which the APT was used for one knee and the MBT for the other. All patients were examined by the authors for an average follow-up period of six years. Hospital for Special Surgery knee scores and a comprehensive roentgenographic evaluation were obtained. No significant difference was noted between the patients with APT and those with MBT, raising serious doubt on the need for the MBT in patients being treated with primary, cemented TKA.

Determining the rotation of thefemoral and tibial components in total knee arthroplasty: A computer tomography technique

Cementing the Tibial Component in Total Knee Arthroplasty: Which Technique is the Best?

Techniques and Technologies in Revision Knee Arthroplasty

Background: The aim of the study was to determine whether the incidence of radiolucent lines can be reduced and cement penetration enhanced by using jet lavage before cementing the tibial component in total knee arthroplasty (TKA). Methods: We prospectively studied a consecutive series of 86 cemented TKAs. In group A (n=44) jet lavage and in group B (n=42) conventional syringe lavage were used to clean the cancellous bone. A standardized cementing technique was applied in all patients. At a minimum follow-up of 1 yr, patients were evaluated clinically and radiographically. The cement bone interface under the tibial component baseplate was divided into four zones according to the Knee Society radiographic evaluation system and evaluated for the presence of radiolucent lines. Results: At latest follow up, all radiographs were evaluated (n=86), and radiolucent lines in different zones were recorded in 7.2 % in group A and in 26% in group B (P&lt;0.05). Cement penetration showed a mean of 2.5±0.9 mm in group A and 1.7±0.8 mm in group B (P&lt;0.001). Conclusions: Routine use of jet lavage in cemented TKA is recommended to reduce the incidence of radiolucent lines, enhance cement penetration, and improve the long-term durability of fixation.

This study aimed to research whether anterior tibial crest is a reliable anatomical reference for rotational alignment of tibial component in TKA. The study included 122 patients who underwent computed tomography angiography (CTA) examination for unilateral lower extremity trauma with normal contralateral lower extremities, including 89 males and 33 females, with an average age of(51.4±16.4) years old(ranged 18 to 81 years old). Picture archiving and communication system (PACS) was used to mark 11 lines including the surgical epicondylar axis (SEA) connecting the most prominent points of the lateral epicondyle and the deepest point of the sulcus on the medial epicondyle of the femur, axis of medial border of patellar tendon (MEPT)connecting the middle of the posterior cruciate ligament (PCL) and medial border of the patellar tendon at the level of a standard tibial cut from 8 mm distal of the lateral tibial joint surface, transverse axis of tibia (TAT) at the level of a standard tibial cut from 8 mm distal of the lateral tibial joint surface, Akagi line connecting the projected middle of the PCL and medial border of the patellar tendon at the tibial attachment, the axis of the medial 1/3 of patellar tendon(M1/3) connecting the projected middle of PCL and the medial 1/3 of the patellar tendon at the patellar tendon attachment level, Insall line connecting the projected middle of the PCL and the medial 1/3 of tibial tubercle, the axis of medial border of tibial tubercle (MBTT) connecting the projected middle of the PCL and medial border of tibial tubercle, as well as the axis of the proximal anterior tibial crest (PATC), axis 1 of the middle anterior tibial crest (MATC1), axis 2 of the middle anterior tibial crest (MATC2) and the axis of the distal anterior tibial crest (DATC) which were marked by connecting the 4 equidistant points on the sharp anterior tibial crest and the projected middle of the PCL. The angles between TAT and SEA as well as the angles between other axes and the perpendicular to SEA were measured. Pairwise differences among the 10 tibial axes were examined using One-Way ANOVA and paired t-test. The angles between the axes of MEPT, Akagi line, M1/3, Insall line, MBTT, PATC, MATC1, MATC2, DATC and the perpendicular to SEA were (-1.6 ±4.5)° , (1.4 ±5.0)° , (10.2±5.1)°, (11.9±5.4)°, (3.6±4.8)°, (12.0±6.9)°, (7.2±8.6)°, (7.1±10.4)°, (6.6±13.5)°, respectively. The angle between TAT and SEA was (4.1±5.3)°. MEPT was external rotation compared to SEA. M1/3, Insall line and PATC were significantly greater than Akagi line, MBTT, TAT (P<0.001). MATC1, MATC2 and DATC were also significantly greater than Akagi line, MBTT axis and TAT (P<0.001). However, MATC1, MATC2 and DATC were also significantly less than M1/3 axis, Insall line and PATC(P<0.01). There were no significant statistical differences between MATC1, MATC2 and DATC(P>0.05). The middle tibial anterior crest can be used as a reference for rotational alignment of tibial component in TKA, and its reliability is better than Insall line, but worse than Akagi line, TAT and MBTT.

Undersizing the Tibial Baseplate in Cementless Total Knee Arthroplasty has Only a Small Impact on Bone-Implant Interaction: A Finite Element Biomechanical Study

Rotational alignment of prosthetic components after total knee arthroplasty (TKA) is predominantly monitored with computer tomography (CT), for example by relating the anatomical transepicondylar axis (a-TEA) of the native femur to the posterior bicondylar axis of the prosthetic component (PBCA). The purpose of the present study was to portray a reliable, novel plain radiographic method that likewise enables the evaluation of rotational positioning of prosthetic components in TKA. Furthermore, it was intended to evaluate the prosthetic femoro-tibial functional behavior under loaded conditions. Modified plain axial radiographs under partial weight bearing (20kg) were performed in 63 patients (63 knees) after TKA. On the obtained radiographs, all established, relevant anatomic, and prosthetic axis and angles reflecting the rotational position of the femoral (i.e., a-TEA/PBCA angle) and tibial component were detected twice by two independent examiners with an interval of one month. Additionally, in 14 cases with anterior knee pain after surgery, radiographic results were compared to obtained computer tomography images; intraclass coefficients (ICC's) for intra- and inter-rater reliability were calculated. All pre-assigned axis and angles could be identified doubtlessly by both examiners in all investigated knees. For all measurements, ICC's for intra-rater and inter-rater reliability ranged from 0.75 to 0.96. The comparison of the radiographic measurements with corresponding CT results (n = 14) revealed no significant differences (p > 0.05). Rotational alignment of the tibial tray in relation to the native tibial bone was not measurable due to display overlaying. Femoro-tibial behaviour of the prosthetic components under partial loading showed a high variability. We were able to establish a new reliable radiographic technique that is able to show the most established and relevant anatomic landmarks and prosthetic axis after TKA to assess the rotational alignment of the prosthetic components in TKA in relation to the distal femur. The evaluation of the femoro-tibal behaviour instead shows a high variability and so far does not allow valid explanatory conclusions.