Alignment Of Femoral Component Research Articles

Determination of optimal component positioning in THA using 3D preoperative planning.

Advancements in three-dimensional (3D) preoperative planning tools can offer surgeons and design engineers detailed feedback and additional opportunities for clinical advancements. The objective of this study is to use a 3D total hip arthroplasty preoperative planning tool to compare femoral component alignment for three different stem systems. The planning tool in this study used morphology data of femoral bones gathered from a CT database, seven from postoperative patients and 63 from statistical shape models (SSMs), to suggest specific implant sizes and optimal placements in 3D to match each specific bone model. Retrospective validations of predicted stem size and femoral version were first performed by comparing planner-chosen and surgeon-implanted stem sizes and version angles for the seven postoperative patients. Next, the alignment of three different stem systems was evaluated using bone models generated from SSMs, with a quantitative focus on component head positioning. In the validation study, the planner accurately selected stem size and orientation compared to the surgeon for all assessed subjects. In the stem evaluation, the three stem systems yielded different accuracies in component placement, with the newest stem system demonstrating the closest restoration of anatomical head center location. It is evident that new stem designs may have the potential for increased accuracy over their predecessors, demonstrating that new stem designs can offer improved intraoperative and postoperative alignment potential. The 3D preoperative planning tools can provide novel and reliable data to both surgeons and design engineers, which can ultimately improve clinical outcomes and future implant designs.

CT-based, robotic-arm assisted total hip arthroplasty (Mako) through anterior approach provides improved cup placement accuracy but no difference in clinical outcomes when compared to conventional technique

BACKGROUND: With the restoration of the natural hip biomechanics, a successful total hip arthroplasty (THA) and long-term survival is pursued. Although robotic THA (rTHA) has been developed to increase accuracy of implant positioning, leg lengths and offsets, discussions about its radiological and clinical advantages over conventional THA (cTHA) continues. OBJECTIVE: The aim of this study was to compare clinical and radiological outcomes of robotic and conventional THA. METHODS: This retrospective study compares functional and radiological outcomes of 82 rTHA with a matched group of 82 cTHA in terms of age, sex, body mass index and preoperative functional scores. The minimum follow up was 12 months for all patients. Functional outcomes were Harris Hip Score (HHS) and the Western Ontario and McMaster University Osteoarthritis index (WOMAC) evaluated pre- and postoperatively. Radiological evaluations included position of cup placement according to Lewinnek and Callanan safe zones, Canal Fill Ratio (CFR), Leg Length Discrepancy (LLD), Lateral offset (LO) and Femoral Component Alignment (FCA). Complications were also evaluated. RESULTS: In the rTHA group, 91.5% (75 out of 82) of the acetabular cups were positioned within the safe zone whereas it was 63.4% (52 out of 82) for the cTHA group (p< 0.001). According to Callanan, they were 84.1% and 50%, respectively (p< 0.001). Between the groups, no statistically significant difference was found in CFR, LLD, HO, FCA, AI, AA, WOMAC, HHS and major complication rates. CONCLUSION: rTHA is superior to cTHA in terms of accuracy and reproducibility of the cup placement, however no apparent clinical benefit was found in short term follow.

A New Concept of Using Femoral Condyles Surface for Femoral Component Alignment During Total Knee Arthroplasty: A Technical Note.

Orthopedic surgeons favor an intramedullary guiding system on the femoral component during total knee arthroplasty (TKA); nevertheless, improper positioning of the entry point affects the final alignment. We have designed a new femoral cutting system for TKA that uses the distal and posterior femoral condyles as reference points for the setting of the cutting system regardless of the femoral canal. This study aims to evaluate the outcomes of this new guiding system. We enrolled a series of 75 consecutive knees undergoing TKA. The alpha, gamma, and hip-knee-ankle (HKA) angles were assessed three months postoperatively. Also, surgical time and intraoperative blood loss were recorded for all patients. Fifteen patients underwent TKA using the mechanical alignment (MA) strategy, and 60 underwent kinematically aligned (KA) TKA. Both groups showed normal coronal and sagittal alignment 3 months postoperatively. The mean intraoperative blood loss was 213.11 ± 52.73ml, which was not different between the two groups (n.s.). The mean surgical time was 43.12 ± 11.62min, which was significantly shorter in the KA-TKA (41.11 ± 3.77min) than in the MA-TKA (49.34 ± 4.56min) (P < 0.001). Using the new guiding system with good femoral alignment, we introduced the easily palpable and available condylar surface as a new landmark for cutting the distal femur in TKA. IV.

Robotic-assisted total knee arthroplasty improved component alignment in the coronal plane compared with navigation-assisted total knee arthroplasty: a comparative study.

The purpose of this study was to directly compare implant placement accuracy and postoperative limb alignment between robotic-assisted total knee arthroplasty and navigation-assisted total knee arthroplasty. This retrospective case-control study included a consecutive series of 182 knees (robotic-assisted group, n = 103 knees; navigation-assisted group, n = 79). An image-free handheld robotic system (NAVIO) or an image-free navigation system (Precision N) was used. Component and limb alignment were evaluated on three-dimensional computed tomography scans and full-length standing anterior-posterior radiographs. We compared the errors between the final intraoperative plan and the postoperative coronal and sagittal alignment of the components and the hip-knee-ankle angle between the two groups. The orientation of the femoral and tibial components in the coronal plane were more accurate in the robotic-assisted group than in the navigation-assisted group (p < 0.05). There was no significant difference in the orientation of the femoral and tibial component in the sagittal plane between the two groups. There were fewer outliers in the tibial coronal plane in the robotic-assisted group (p < 0.05). There was also no significant difference in the frequency of outlying values for coronal or sagittal alignment of the femoral component or sagittal alignment of the tibial component or the hip-knee-ankle angle between the two groups. Robotic-assisted total knee arthroplasty using a handheld image-free system improved component alignment in the coronal plane compared with total knee arthroplasty using an image-free navigation system. Robotic surgery helps surgeons to achieve personalised alignment that may result in better clinical outcomes.

Association of sagittal alignment of tibial and femoral components with clinical outcome in total knee arthroplasty: A prospective cohort study

BackgroundIn total knee replacement component alignment is a very crucial parameter to achieve better clinical outcomes. Only a few studies exist in the literature on the association between sagittal alignment of components and clinical outcomes. The study aimed to measure the functional outcome and association between the sagittal alignment of total knee replacement components and their clinical outcome. Material & methodsProspectively we collected data of 81 knees (cases) following total knee replacement. The sagittal femoral angle, anterior and posterior tibial slopes were assessed on 2nd postoperative week using a lateral radiograph. Based on these measures 2 groups were made. Group A comprises of the femoral component which was further divided into A1 (41 cases) and A2 (40 cases) based on the component's sagittal femoral angle in flexion or extension.Group B comprises of Tibial component subgrouped based on the degree of Tibal angle as the posterior tibial slope or anterior tibial slopes. The B1 subgroup has posterior tibial slope of more than 5° (23 cases), B2 posterior tibial slope within 5° (53 cases), and B3 anterior tibial slope (5 cases). Preoperative and follow-ups at one month, 6 months, and 3 year; the functional assessment was performed using the American Knee Society score and Oxford knee scores. The duration to raise the leg straight (in days) was also measured. Results52 patients (81 total knee replacement cases) with a mean age of 62.88 ± 8.21 were enrolled. Results showed significant improvement in mean American Knee Society score (preoperative 32.91 ± 2.61 to 86.68 ± 2.52 postoperatively at 3 years; P < 0.001) and mean Oxford knee score (preoperative 34.69 ± 1.06 to 19.20 ± 1.91 postoperatively at 3-years; P < 0.001). The correlation of American Knee Society score between the femoral component angle and tibial component angle suggested that the maximum correlation was between Group A2 (Femoral angle = 91 to 95) and Group B2 (Tibal angle = 86 to 90), with p-value <0.0001. ConclusionsThere is a positive association between the proper sagittal alignment of femoral component and tibial component in total knee replacement with clinical outcome. The functional outcome (in terms of mean American Knee Society score) is better when the femoral component is positioned in extension and the posterior tibial slope of less than 5° is achieved.

Valgus alignment of the femoral component is associated with higher revision rates 10years after TKA.

Appropriate positioning and alignment of tibial and femoral component in primary total knee arthroplasty (TKA) are factors of major importance directly related to patient satisfaction and implant survival. Most literature works elaborate on overall post-operative alignment and its correlation to implant survival. However, less is known about the impact of individual component alignment. The purpose of this study was to investigate the effect of undercorrection of overall alignment as well as the effect of individual tibial and femoral component alignment on the post-operative failure rate after total knee arthroplasty. Clinical and radiographic data of primary TKA cases from 2002 to 2004, with a minimum of 10-year follow-up, were retrospectively reviewed. The pre- and post-operative hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured on weight-bearing, full-length antero-posterior lower limb radiographs. Statistical analysis was performed to establish the correlation between both overall and implant alignment and revision rate. In total, 379 primary TKA cases were evaluated. The mean time of follow-up was 12.9years (range 10.3-15.9years, SD = 1.8). Nine out of 379 cases were revised due to aseptic loosening; the mean time to revision was 5.5years (range 1.0-15.5years, SD = 4.6). Varus undercorrection of overall alignment was not associated with a higher rate of revision (p = 0.316). Post-operative valgus femoral alignment (mLDFA < 87°) contributed to a significant decreased prosthesis survival in contrast to neutral femoral alignment (revision rate valgus group: 10.7% and neutral group: 1.7%; p = 0.003). Post-operative tibial mechanical alignment was not identified as a significant predictor for implant survival (revision rate varus group: 2.9% and neutral group: 2.4%; p = 0.855). Primary TKA showed significantly higher revision rates when the femoral component was placed in > 3° of valgus (mLDFA < 87°). In contrast, postoperative overall residual varus alignment (HKA) and varus alignment of the tibial component were not related to higher revision rates at a minimum 10-year follow-up after TKA. These findings should be considered when choosing component position in individualised TKA. III.

Does Automated Impaction Improve Femoral Component Sizing and Alignment in Total Hip Arthroplasty?

BackgroundWhile automated impaction can provide a more standardized process for femoral canal preparation, little is known regarding its effect on femoral component sizing and position. The purpose of our study was to directly compare femoral component canal fill ratio (CFR) and coronal alignment between primary total hip arthroplasty (THA) procedures performed with automated impaction versus manual mallet impaction. MethodsA retrospective analysis was performed on 184 patients who underwent primary THA by a single arthroplasty surgeon between 2017 and 2021 with a modern cementless femoral component using either the direct anterior or posterolateral approach. The final cohort was divided into 2 groups based on impaction technique during broaching: automated (N = 122) or manual (N = 62). A propensity score match was used to match for age, body mass index, sex, high versus standard offset stem, and preoperative femoral bone quality. Radiographic review was performed to measure intramedullary prosthetic CFR and coronal alignment. ResultsThe automated cohort trended toward the use of a larger stem (5.67 versus 4.82, P = .006) and had a larger CFR at all 4 levels within the proximal femur (P = .004). The automated cohort had a more valgus and reliable coronal alignment (−0.57 (SD 1.50) versus −0.03 (SD 2.17) degrees, P = .03) and significantly shorter operative time (mean 78 versus 90 minutes, P < .001). There were no intraoperative or postoperative periprosthetic fractures in either cohort. ConclusionAutomated impaction in primary THA is a safe technique for femoral preparation, which resulted in improved stem coronal alignment, optimized canal fill within the proximal femur, and reduced operative times.

3D-printed, patient-specific cutting guides improve femoral and tibial cut alignment in canine total knee replacement.

The purpose of this cadaveric study was to determine whether patient-specific guides (PSGs) improve the accuracy of tibial and femoral cut alignment in canine total knee replacement (TKR), as compared with generic cutting guides. Original research. Sixteen pelvic limbs from skeletally mature medium- to large-breed canine cadavers. Specimens were randomly allocated to one of two groups (PSG or Generic; N = 8/group). In the Generic group, femoral and tibial ostectomies were made using the standard canine TKR femoral cutting blocks and tibial alignment guide. In the PSG group, the cuts were made using a series of custom 3D-printed cutting guides. "Planned" and "actual" tibial and femoral cut alignments were compared in the frontal and sagittal planes, and errors were calculated by subtracting actual from planned values. Use of 3D-printed PSGs improved tibial cut alignment in the frontal plane but not the sagittal plane. PSGs also improved the alignment of the cranial and distal femoral ostectomies but did not impact varus-valgus alignment. These findings support the use of PSGs for TKR in dogs. Clinical trials are now needed to determine whether the benefits of PSGs translate into measurable improvements in joint function and implant longevity. PSGs have the potential to improve femoral and tibial component alignment in canine TKR.

Concordance in Radiological Parameters of Different Knee Views After Total Knee Arthroplasty.

Background Total knee arthroplasty (TKA) is a cost-effective treatment for the end-stage of knee osteoarthritis. Despite the improvements in this surgery, a significant percentage of patients still report dissatisfaction after knee arthroplasty.Radiological results have been used to predict clinical outcomes and satisfaction after knee replacement. This study aims to evaluate the concordance of a set of radiographic views to assess alignment on total knee arthroplasty. Methods A concordance study was designed with 105 patients (130 TKA) that underwent conventional total knee arthroplasty cruciate-retaining design recruited for the study and scheduled for their annual radiograph control. Measurements were performed on the following radiograph after total knee replacement: full-length standing anteroposterior and lateral radiograph, anteroposterior standing, lateral and axial knee view, and the knee "seated view". A musculoskeletal radiologist and a knee surgeon were recruited to perform the radiological measurement and then estimate the interobserver agreement. Results There was an excellent correlation between Limb Length (LL), Hip-knee-ankle angle (HKA), Sagittal mechanical tibial component alignment (smTA), extension lateral and medial joint space (eLJS and eMJS), 90º flexion lateral and medial joint space (fLJS and fMJS) and Sagittal anatomic lateral view tibial component alignment (saLTA); the good correlation between Mechanical lateral femoral component alignment (mLFA), Sagittal anatomic tibial component alignment (saTA), Sagittal anatomic lateral view femoral component alignment 2 (saLFA2), Patella Height (PH); and moderate to poor correlation for the rest of measurements. Conclusion Excellent and good concordance can be achieved for radiographic measurements in different knee views to assess results after TKA. These findings must encourage future studies to address functional and survival outcomes using all knee views and not just one plane.

Ground kinematically aligned total knee arthroplasty: new personalized technique which enables a stable knee with deep flexion

PurposeThis study aimed to evaluate kinematically aligned total knee arthroplasty (KA-TKA) targeting the neutral ground mechanical axis (MA) (hip-to-calcaneus axis), the line from the hip centre to the bottom of the calcaneus, (ground KA-TKA) in terms of its comparison with tibia-restricted modified KA-TKA (modified KA-TKA).MethodsThis retrospective cohort study included 106 consecutive patients who underwent unilateral KA-TKA for varus osteoarthritis (OA) (60 modified KA-TKAs and 46 ground KA-TKAs). After 1:1 propensity score matching, 60 patients (30 pairs) were matched between the groups with comparable demographic data. The hip-knee-ankle (HKA) angle, coronal femoral component alignment (FCA), and coronal tibial component alignment (TCA) were compared between groups. Intraoperative soft tissue balance, including the joint component gap and varus/valgus balance, was also compared between the groups. One year postoperatively, the clinical outcomes, including the range of motion and 2011 Knee Society Score, were compared between groups.ResultsThe HKA angle and FCA/TCA were not significantly different between groups. Whereas the varus/valgus balance showed no significant differences between groups, smaller joint component gaps were found throughout the range of motion in the ground KA-TKA group than in the modified KA-TKA group. Despite no difference in clinical scores between groups, a significantly deeper postoperative flexion angle was achieved in the ground KA-TKA group than in the modified KA-TKA group (p < 0.05).ConclusionTargeting neutral ground MA in KA-TKA for patients with varus OA has the potential to provide a better flexion angle with stable intraoperative soft tissue balance.

Correcting for distal femoral asymmetry is necessary to determine postoperative alignment deviations from planned alignment of the femoral component

BackgroundOne method for assessing the accuracy of manual, patient-specific, navigational, and robotic-assisted total knee arthroplasty (TKA) instrumentation is to use a post-operative computer tomogram and determine the deviation of the femoral component alignment relative to the planned alignment in the native (i.e. healthy) contralateral distal femoral epiphysis. However, side-to-side asymmetry might introduce errors which inflate alignment deviations. This study quantified asymmetry in the distal femoral epiphysis. MethodsHigh resolution CT images (0.5 mm slice thickness) were acquired from bilateral lower limb specimens of 13 skeletally mature subjects with no skeletal abnormalities. Images were segmented to generate 3D femur models. Asymmetry was quantified by differences in positions and orientations required to shape-match the distal epiphysis of the mirror 3D femur model to the distal epiphysis of the contralateral 3D femur model. ResultsAsymmetry was due to random rather than systematic differences. Random differences (i.e. standard deviations) in proximal–distal (P-D) and anterior-posterior (A-P) positions were 1.1 mm and in varus-valgus (V-V) and internal-external (I-E) orientations were 0.9° and 1.3°, respectively. These represented substantial relative errors of up to 50 % in previously reported overall alignment deviations. ConclusionsAlthough small in an absolute sense, asymmetry of the distal femur epiphysis introduced substantial relative errors when assessing accuracy of femoral component alignment in TKA. When post-operative computer tomograms are used to assess the accuracy of manual, patient specific, navigational, and robotic-assisted TKA instrumentation, the overall deviation should be corrected for asymmetry to better indicate the accuracy of the surgical technique.

Curve-on-curve technique does not improve tibial coverage in total knee arthroplasty in comparison to tibial tuberosity technique with use of anatomical implants: randomized controlled trial

IntroductionDuring the last years, main attention while performing total knee replacement was paid to femoral component alignment; however, there is still lack of studies concerning tibial baseplate rotational alignment, especially in terms of anatomical designs of knee prosthesis. Some recent studies proved that tibial baseplate malrotation might be a cause of knee pain and patients’ dissatisfaction. The aim of this study was to compare tibial component rotation and its coverage on the tibial plateau achieved with curve-on-curve and tibial tuberosity techniques (t-t technique) with use of anatomic knee designs with asymmetric tibial baseplate.Materials and methodsA total of 88 patients were randomly assigned in a 1:1 ratio to undergo total knee arthroplasty with use of the PERSONA PS (Zimmer Biomet) knee design with an asymmetric baseplate. The rotation of the tibial component was assessed and performed with two different techniques: curve-on-curve technique and tibial tuberosity technique. Tibial component rotation was measured on computed tomography (CT) scans using the method suggested by Benazzo et al. and designed for asymmetrical implants. For the measurement of the tibial bone coverage, the component surface area was outlined and measured on a proper CT section, then the tibial cut surface area was outlined and measured on a section just below the cement level. Pre- and post-operative range of motion was measured by another independent researcher 12 months post-operatively during follow-up visit.ResultsThere was a statistically significant difference between both groups in median value of tibial rotation angle: 7° (interquartile range (IQR) = 0–12) in curve-on-curve technique group vs 2° (IQR-1–7) in tibial tuberosity technique group, probability value (p) = 0.0041, with values above 0 meaning external rotation of the component. There was no statistically significant difference between both groups in terms of range of motion (ROM) with average values of 124.3° ± 13.0° for curve-on-curve technique and 125.6° ± 12.8° for t-t technique with p = 0.45. There was a statistically insignificant difference between both groups in terms of coverage percentage in slight favor for curve-on-curve technique (85.9 ± 4.2 vs 84.5 ± 4.8, p = 0.17).ConclusionIn this study, no difference between the groups in terms of tibial bone coverage and range of motion was proved, even though both techniques differed significantly with values of tibial rotation. Future studies should be focused on influence of specific values of tibial rotation on patient-reported outcomes and survivorship of anatomic knee implants.

Effect of component rotational alignment on femorotibial rotational alignment in total knee arthroplasty: comparison between mobile and fixed bearing

Purpose“Rotational self-alignment mechanism" was designed for mobile-bearing total knee arthroplasty (MB TKA) to maintain a natural femorotibial rotational alignment independent of component rotational alignment. However, it is clinically unknown if the influence of component rotational alignment on a postoperative anatomical femorotibial rotational angle (FTRA) in MB TKA is eliminated. This study aimed to determine the effect of component rotational alignments on postoperative anatomical FTRA in MB TKA as compared to fixed-bearing TKA (FB TKA). MethodsThis research comprised a total of 161 knees: 54 ​MB TKAs and 107 FB TKAs. In computed tomography, the postoperative FTRA and rotational alignment of tibial and femoral components to anatomical axes were assessed, and the association between the postoperative FTRA and perioperative radiographic data, including component rotational alignments, was examined. ResultRotational alignments of both tibial and femoral components did not correlate postoperative FTRA in MB TKA (tibial component: r ​= ​−0.15, p ​= ​0.26, femoral component: r ​= ​0.22, p ​= ​0.10), however, in FB TKA, rotational alignment of tibial component did correlate postoperative FTRA, while that of femoral component did not (tibial component: r ​= ​−0.65, p ​< ​0.01, femoral component: r ​= ​0.17, p ​= ​0.07). In both groups, preoperative FTRA was substantially associated with postoperative FTRA (MB TKA: r ​= ​0.65, p ​< ​0.01, FB TKA: r ​= ​0.33, p ​< ​0.01). ConclusionsComponent rotational alignments did not affect postoperative anatomical rotational femorotibial alignment in MB TKA. Whereas the rotational alignment of the tibial component has a significant impact on the postoperative femorotibial rotational alignment in FB TKA.

Prosthetic orientation, limb alignment, and soft tissue balance with bi-cruciate stabilized total knee arthroplasty: a comparison between the handheld robot and conventional techniques

PurposeThis study aimed to examine the prosthetic orientations, limb alignment, intraoperative soft tissue balance, and early clinical outcomes associated with the use of the relatively new handheld robot technique compared to those associated with the use of the conventional alignment guide for bi-cruciate stabilized total knee arthroplasty (TKA).MethodsThis retrospective cohort study compared the prosthetic orientation and limb alignment of 35 patients who underwent TKA using robotic assistance (robot group) with those of patients who underwent TKA using a conventional alignment guide (control group). The coronal femoral component alignment (FCA), coronal tibial component alignment (TCA), and the hip-knee-ankle (HKA) angle were compared between groups. Intraoperative soft tissue balance, including the joint component gap and varus/valgus balance assessed by an offset-type tensor, were also compared between groups. One year postoperatively, the clinical outcomes, including the range of motion and 2011 Knee Society Score (KSS), were compared between groups.ResultsThe HKA angle and FCA were 0.1° varus and 0.1° varus, respectively, in the robot group and 1.3° varus and 1.3° varus, respectively, in the control group. The difference in the HKA angle and the FCA, but not the TCA, between groups was statistically significant (p < 0.05). The intraoperative soft tissue balance showed more stable joint component gaps and varus/valgus balances throughout the range of motion in the robot group than in the control group. Clinical outcomes of the robot group showed superior 2011 KSS subscales compared to those of the control group.ConclusionThe accuracy of the implantations and stable soft tissue balance in the robot group were superior to those of the control group. The robot group also had superior patient-reported scores for early clinical outcomes.

Comparison of intramedullary versus extramedullary alignment technique in total knee arthroplasty: A PRISMA-compliant meta-analysis.

This meta-analysis aimed to compare the efficacy of intramedullary and extramedullary femoral alignment technique in treating total knee arthroplasty (TKA) patients. PubMed, Embase, Cochrane library, Chinese National Knowledge Infrastructure, and Weipu databases were electronically searched. Potential clinical studies that investigated the effect and safety of intramedullary versus extramedullary femoral alignment technique in TKA patients were searched. The primary outcome was lower limb coronal alignment. Stata 12.0 was used for meta-analysis. This meta-analysis included 12 prospective randomized controlled studies that reported data on 935 TKA patients. No significant difference was noted in lower limb coronal alignment, coronal alignment of femoral component, sagittal alignment of femoral component and tibial slope between intramedullary and extramedullary alignment techniques ( P > .05). Further, extramedullary alignment technique significantly decrease the total blood loss than intramedullary alignment technique (weighted mean difference: -86.52; 95% confidence interval: -115.05--57.99; P = .000) and subsequently transfusion rate (risk ratio: 0.57; 95% confidence interval: 0.41-0.79; P = .000). Finally, there was no significant difference between intramedullary and extramedullary alignment techniques in terms of the total complications ( P > .05). The present meta-analysis showed that intramedullary and extramedullary femoral alignment technique had comparable precise profiles. And extramedullary femoral alignment technique could reduce blood loss and blood transfusion. Total complications were comparable between the groups. More randomized controlled trials with large samples are required to verify the comparison of intramedullary and extramedullary femoral alignment technique in TKA patients.

A retrospective study of articular surface mounting computer-assisted total knee arthroplasty in alignment, knee function, and survival

Background Hong Kong Chinese exhibits a greater varus lower limb mechanical axis and coronal bowing when compared to Caucasians. This anatomical difference may affect the accuracy of bone cuts in total knee arthroplasty (TKA) using western anatomy-based intramedullary TKA cutting jigs. Use of computer navigation may avoid suboptimal cuts due to altered anatomy. This is the first study evaluating clinical function, radiological alignment and long-term survival of computer-assisted TKA amongst Hong Kong Chinese patients. Methods Retrospective study comparing articular surface mounting computer-assisted TKA (ASM-CATKA) and conventional TKA performed in a single centre from 2008 to 2010. Patients were followed up for ​assessment of clinical parameters including range of motion, Knee Society Knee score, and radiological parameters such as limb alignment, component alignment, and survival. Results Seventy-five patients were included in this study. Baseline clinical and radiological data were similar between groups. The computer-navigated group had superior radiological mechanical alignment ( p &lt; 0.001), tibial component alignment ( p = 0.016) and femoral component alignment ( p &lt; 0.01) when compared to conventional TKA. There were no differences in knee scores ( p = 0.488), range of motion ( p = 0.432) and survival at 117 months ( p = 0.986) between the two groups. Conclusion This retrospective study showed that ASM-CATKA was more accurate in achieving neutral mechanical axis and component alignment amongst Hong Kong Chinese. Clinical outcomes and implant survival were comparable.

Robotic-assisted total knee arthroplasty improves the rotational mismatch between femoral and tibial components, but not the forgotten joint score 12: a single-center retrospective cohort study

PurposeThe primary aim of this study was to compare postoperative short-term patient reported outcome measurements (PROMs) and rotational mismatch between femoral and tibial following conventional jig-based total knee arthroplasty (Conv-TKA) versus robotic-assisted TKA (RA-TKA) using three-dimensional computed tomography (3DCT) measurements.MethodsThis retrospective, consecutive case–control trial included 83 patients with varus osteoarthritis of the knee undergoing Conv-TKA versus RA-TKA using bi-cruciate stabilized TKA. The rotational mismatch of the femoral and tibial components between the two groups were compared using 3DCT measurements. PROMs (2011 Knee Society Score (KSS), forgotten joint score-12 (FJS-12), patella score were compared in patients between 1 and 2 years postoperatively.ResultsThe two groups did not exhibit significant differences in any of the following preoperative factors: age at surgery, body mass index (BMI), preoperative range of motion (ROM), hip-knee-ankle (HKA) angle. There were no significant differences in postoperative HKA angle and tibial rotation angle, the absolute values of the femoral rotational angle and rotational mismatch were significantly smaller in the RA-TKA group than in the Conv-TKA group (both p < 0.01). Neither Postoperative PROMs (2011 KSS: pain, patient satisfaction, patient expectation, advanced activities score) nor patella score differed significantly between the groups, but FJS-12 was significantly better in the Conv-TKA group than in the RA-TKA group (p < 0.01).ConclusionsRA-TKA did not improve FJS-12 compared to Conv-TKA, but did result in more accurate rotational alignment of femoral component and rotational mismatch between the femoral and tibial components.Level of evidenceIV.

Spacer Block Technique Was Superior to Intramedullary Guide Technique in Coronal Alignment of Femoral Component after Fixed-Bearing Medial Unicompartmental Knee Arthroplasty: A Case-Control Study.

Backgrounds and Objectives: The spacer block technique in unicompartmental knee arthroplasty (UKA) has still a concern related to the precise position of the component in the coronal and sagittal planes compared to intramedullary guide technique. The purposes of this study were to explore whether the spacer block technique would improve the radiological alignment of implants and clinical outcomes compared with the outcomes of the intramedullary guide technique in fixed-bearing medial UKA. Materials and Methods: In total, 115 patients who underwent unilateral, fixed-bearing medial UKA were retrospectively reviewed and divided into group IM (intramedullary guides; n = 39) and group SB (spacer blocks; n = 76). Clinical assessment included range-of-motion and patient-reported outcomes. Radiological assessment included the mechanical femorotibial angle, coronal and sagittal alignments of the femoral and tibial components, and coronal femorotibial congruence angle. Results: All clinical outcomes showed no significant differences between groups. The coronal femoral component angle was valgus 2.4° ± 4.9° in IM group and varus 1.1° ± 3.2° (p < 0.001). In group IM, the number of outlier in coronal femoral component angle (<−10° or 10°<) was 3 cases, while in group SB, there was no outlier (p = 0.014). The coronal femorotibial congruence angle was significantly less in group SB (mean 1.9°, range, −3.2°~8.2°) than in group IM (mean 3.4°, range, −9.6°~16.5°) (p = 0.028). Conclusions: In the group SB, the coronal alignment of femoral component was closer to neutral, and outlier was less frequent than in the group IM. The spacer block technique was more beneficial in achieving proper coronal alignment of the femoral component and congruence of femorotibial components compared to the intramedullary guide technique in fixed-bearing medial UKAs.

Fixed distal femoral resection with a valgus cutting angle of 3° is more appropriate in intra-articular valgus deformity than juxta-articular valgus deformity in total knee arthroplasty: a retrospective single center study.

The traditionally recommended fixed valgus cutting angle (VCA) of 3° is used as the standard method in total knee arthroplasty (TKA) for valgus deformity. The accuracy of distal femur cutting can be affected by the type of valgus deformity because the intramedullary rod for distal femoral resection can become impinged on the femoral cortex. The purpose of this study is to analyze the accuracy and precision of a VCA of 3° in mechanical alignment in TKA for valgus deformity, based on the type of the deformity. TKAs with a fixed VCA of 3° performed in 110 intra-articular and 102 juxta-articular valgus knees were retrospectively reviewed. The age (65.8 vs. 66.1 years), sex (female: male =78/32 vs. 70/32), body mass index (26.0 vs. 26.0), and severity of deformities (valgus 12.1 vs. valgus 12.5) were not significantly different (P>0.647). The mechanical-lateral-distal-femoral angle (mLDFA) and anatomical-mechanical-axis angle (AMA-A) were evaluated. The adjusted-VCA (aVCA) was defined as the maximum angle within the range without the intramedullary rod impinging on the femoral cortex. The proportion of well-aligned femoral component (mLDFA <90°±3°) was assessed. The correlation between AMA-A-3° or aVCA-3° and postoperative mLDFA-90° was analyzed. Despite the larger AMA-A in the juxta-articular group (6.2° vs. 6.8°, P<0.001), the aVCA was lesser in the juxta-articular group (5.4° vs. 4.1°, P<0.001). The mLDFA was more varus in the intra-articular group (91.7° vs. 90.6°, P<0.001) postoperatively. The proportion of well-aligned femoral component was higher in the juxta-articular group (85.3% vs. 70%, P=0.009). Postoperative mLDFA-90° was moderately correlated with aVCA-3° (r=0.301, r=387), but weakly correlated with AMA-A-3° (r=0.274, r=294) in both groups. Although a fixed VCA of 3° is a reliable method in achieving mechanical alignment in valgus deformity, it can be more appropriate in juxta-articular deformity than in intra-articular deformity. The aVCA is a more reasonable predictor of femoral component alignment than the AMA-A, considering the femoral cortex impingement of the intramedullary rod.

A novel way of quantifying bone defect in primary total knee replacements using plain radiographs.

Bone defect assessment in primary advanced knee arthritis can present a challenge for the surgeon and lead to unfavourable outcomes if not adequately determined during preoperative planning. The aim of this study was to introduce a new, simple and quick way to assess and quantify bone defect using short film radiographs and utilising it to choose the total knee prosthesis. This is a prospective case series of patients who underwent TKA (Total Knee Arthroplasty) using various types of prostheses. Three different angles - Tibiofemoral angle, MPTA (medial proximal tibial angle), and JLCA (joint line convergence angle) - were measured preoperatively to evaluate limb alignment, placement of the tibial, and femoral components of total knee prosthesis. Postoperatively roentgenographic index introduced by Lotke et al was used to assess our preoperative methodology. The American knee society score was used pre- and postoperatively up to one year. A total of eight knees of six patients were analysed (four males, two females). The mean age of the patients was 57.75±5.701 years. All the knees were in varying degrees of varus deformity preoperatively. The accuracy of the preoperatively used radiological angles was analysed by postoperative measurement of tibiofemoral angle (d), tibial anatomical axis (b) and femoral anatomical axis (a), and Roentgenographic index as suggested by Lotke et al. Postoperatively, all the knees were in valgus with tibiofemoral angle (d) 6.50±0.926, tibial component alignment (b) mean was 89±1.195, and femoral component alignment (a) mean was 5.13±0.991 valgus. Mean roentgenographic index was 89.38±3.292. American knee society score improved at one-year follow-up postoperatively and was statistically significant with p<0.001. In this study, a new classification for bone defects in primary arthritic knees by utilising simple plain radiograph short films and as a guide for implant selection is proposed.