The position and orientation of total knee replacement components: A COMPARISON OF CONVENTIONAL RADIOGRAPHS, TRANSVERSE 2D-CT SLICES AND 3D-CT RECONSTRUCTION
01 May 2011-Journal of Bone and Joint Surgery-british Volume (British Editorial Society of Bone and Joint Surgery)-Vol. 93, Iss: 5, pp 629-633
TL;DR: 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components in a poorly functioning TKR with concerns over component positioning, and are recommend 3D-CT as the investigation of choice.
Abstract: We studied the intra- and interobserver reliability of measurements of the position of the components after total knee replacement (TKR) using a combination of radiographs and axial two-dimensional (2D) and three-dimensional (3D) reconstructed CT images to identify which method is best for this purpose. A total of 30 knees after primary TKR were assessed by two independent observers (an orthopaedic surgeon and a radiologist) using radiographs and CT scans. Plain radiographs were highly reliable at measuring the tibial slope, but showed wide variability for all other measurements; 2D-CT also showed wide variability. 3D-CT was highly reliable, even when measuring rotation of the femoral components, and significantly better than 2D-CT. Interobserver variability in the measurements on radiographs were good (intraclass correlation coefficient (ICC) 0.65 to 0.82), but rotational measurements on 2D-CT were poor (ICC 0.29). On 3D-CT they were near perfect (ICC 0.89 to 0.99), and significantly more reliable than 2D-CT (p < 0.001). 3D-reconstructed images are sufficiently reliable to enable reporting of the position and orientation of the components. Rotational measurements in particular should be performed on 3D-reconstructed CT images. When faced with a poorly functioning TKR with concerns over component positioning, we recommend 3D-CT as the investigation of choice.
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TL;DR: The present study introduces functional knee phenotypes, which are a combination of all previously introduced phenotypes and enable a simple, but detailed assessment of a patient’s individual anatomy and could be a helpful tool to individualize the approach to TKA.
Abstract: The currently used system to classify the lower limb alignment (neutral, varus, valgus) does not consider the orientation of the joint line or its relationship to the overall lower limb alignment. Similarly, current total knee arthroplasty (TKA) alignment concepts do not sufficiently consider the variability of the native coronal alignment. Therefore, the purpose of this study was (1) to introduce a new classification system for the lower limb alignment, based on phenotypes, and (2) to compare the alignment targets of different TKA alignment concepts with the native alignment of non-osteoarthritic patients. Two recent articles phenotyped the lower limb, the femur and tibia of 308 non-osteoarthritic knees of 160 patients [male to female ratio = 102:58, mean age ± standard deviation 30 ± 7 years (16–44 years)]. The present study introduces functional knee phenotypes, which are a combination of all previously introduced phenotypes. The functional knee phenotypes therefore enable an evaluation of all parameters in relation to each other and thus a comprehensive analysis of the coronal alignment. The existing functional knee phenotypes in the female and male population were investigated. In addition, how many non-osteoarthritic knees had an alignment within the range of current TKA alignment targets (mechanical, anatomical and restricted kinematic alignment) was investigated. Therefore, it was defined which functional knee phenotypes represented a target of the TKA alignment concepts and which percentage of the population had such a phenotype. Out of 125 possible functional knee phenotypes, 43 were found (35 male, 26 and 18 mutual). The most common functional knee phenotype in males was NEUHKA0° + NEUFMA0° + NEUTMA0° (19%), followed by VARHKA3° + NEUFMA0° + VARTMA0° (8.2%). The most common functional knee phenotype in females was NEUHKA0° + NEUFMA0° + NEUTMA0° (17.7%), closely followed by NEUHKA0° + NEUFMA0° + VALTMA0° (16.6%). The functional knee phenotype representing a mechanical alignment target was found in 5.6% of the males and 3.6% of the females. The phenotype representing an anatomical alignment target was found in 18% of the males and 17% in females. Five of the nine phenotypes representing a restricted kinematic alignment target were found in this population (male 5, female 4, mutual 4). They represented 31.3% of all males and 45.1% of all females. A more individualized approach to TKA alignment is needed. The functional knee phenotypes enable a simple, but detailed assessment of a patient’s individual anatomy and thereby could be a helpful tool to individualize the approach to TKA. III, retrospective cohort study.
148 citations
TL;DR: Depression, anxiety, a tendency to somatize and psychological distress were identified as significant predictors for poorer clinical outcomes before and/or after TKA.
Abstract: Patient-based and psychological factors do influence outcome in patients undergoing total knee arthroplasty (TKA). The purpose was to investigate if preoperative psychological factors influence the subjective and objective outcomes 6 weeks, 4 months and 1 year after TKA. Our hypothesis was that there is a significant influence of psychological factors on clinical outcome scores before and after TKA. A prospective, longitudinal, single-cohort study investigating the correlation of depression, control beliefs, anxiety and a variety of other psychological factors with outcomes of patients undergoing TKA was performed. A total of 104 consecutive patients were investigated preoperatively using the Beck`s depression inventory, the State-Trait Anxiety Index, the questionnaire for assessment of control beliefs and the SCL-90R inventory. The Knee Society Clinical Rating System (KSS) and the WOMAC were used. Analysis of TKA position was performed on radiographs according to Ewald et al. Correlation of psychological variables with outcomes was performed (p < .05). Self-efficacy did not influence clinical scores. More depressed patients showed higher pre- and postoperative WOMAC scores, but no difference in amelioration. KSS scores were not influenced. Patients with higher State and Trait Anxiety Indexes had higher WOMAC and lower KSS scores before and after the operation, but most significant correlations were <0.3. Several SCL-90 dimensions had significant correlations with pre- and postoperative clinical scores, but not with their amelioration. The SCL-90 subscore for somatization and the overall SCL-90 significantly correlated with the WOMAC, KSS before and after TKA. Depression, anxiety, a tendency to somatize and psychological distress were identified as significant predictors for poorer clinical outcomes before and/or after TKA. Standardized preoperative screening and subsequent treatment should become part of the preoperative work-up in orthopaedic practice. Prognostic prospective, Level I.
145 citations
Cites background or methods from "The position and orientation of tot..."
...were not able to obtain 3D-CT for analysis of TKA component position, which has to be considered as the current gold standard [18]....
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...This is the current accepted method, but the method is prone to measurement errors [18]....
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TL;DR: Kinematically aligned TKAs appear to have comparable short-term results to mechanically aligned TkAs with no significant differences in function one year post-operatively, according to Bone Joint J 2016.
Abstract: Aims Our aim was to compare kinematic with mechanical alignment in
total knee arthroplasty (TKA). Patients and Methods We performed a prospective blinded randomised controlled trial
to compare the functional outcome of patients undergoing TKA in
mechanical alignment (MA) with those in kinematic alignment (KA).
A total of 71 patients undergoing TKA were randomised to either
kinematic (n = 36) or mechanical alignment (n = 35). Pre- and post-operative
hip-knee-ankle radiographs were analysed. The knee injury and osteoarthritis
outcome score (KOOS), American Knee Society Score, Short Form-36,
Euro-Qol (EQ-5D), range of movement (ROM), two minute walk, and timed
up and go tests were assessed pre-operatively and at six weeks,
three and six months and one year post-operatively. Results A total of 78% of the kinematically aligned group (28 patients)
and 77% of the mechanically aligned group (27 patients) were within
3° of their pre-operative plan. There were no statistically significant
differences in the mean KOOS (difference 1.3, 95% confidence interval
(CI) -9.4 to 12.1, p = 0.80), EQ-5D (difference 0.8, 95% CI -7.9
to 9.6, p = 0.84), ROM (difference 0.1, 95% CI -6.0 to 6.1, p =
0.99), two minute distance tolerance (difference 20.0, 95% CI -52.8 to
92.8, p = 0.58), or timed up and go (difference 0.78, 95% CI -2.3
to 3.9, p = 0.62) between the groups at one year. Conclusion Kinematically aligned TKAs appear to have comparable short-term
results to mechanically aligned TKAs with no significant differences
in function one year post-operatively. Further research is required
to see if any theoretical long-term functional benefits of kinematic
alignment are realised or if there are any potential effects on
implant survival. Cite this article: Bone Joint J 2016;98-B:1360–8.
140 citations
TL;DR: 3D-reconstructed CT scans confirmed the great variability of the joint line orientation in non-osteoarthritic knees and introduced femoral and tibial phenotypes, which clearly shows the need for a more individualized approach in TKA.
Abstract: There is a lack of knowledge about the joint line orientation of the femur and tibia in non-osteoarthritic knees. The primary purpose of the present study was to evaluate the orientation of the joint lines in native non-osteoarthritic knees using 3D-reconstructed CT scans. The secondary purpose was to identify knee phenotypes to combine the information of the femoral and tibial alignment. A total of 308 non-osteoarthritic knees of 160 patients (male to female ratio = 102:58, mean age ± standard deviation 30 ± 7 years (16–44 years) were retrospectively included from our registry. All patients received CT of the knee according to the Imperial Knee Protocol. The orientation of the femoral and tibial joint line was measured in relation to their mechanical axis (femoral mechanical angle, FMA, and tibial mechanical angle, TMA) using a commercially planning software (KneePLAN 3D, Symbios, Yverdon les Bains, Switzerland). The values of FMA and TMA were compared between males and females. Descriptive statistics, such as means, ranges, and measures of variance (e.g. standard deviations), were presented. Based on these results, phenotypes were introduced for the femur and tibia. These phenotypes, based on FMA and TMA values, consist of a mean value and cover a range of ± 1.5° from this mean (3° increments). The distribution of femoral and tibial phenotypes, and their combinations (knee phenotypes) were calculated for the total group and for both genders. The overall mean FMA ± standard deviation (SD) was 93.4° ± 2.0° and values ranged from 87.9° varus to 100° valgus. The overall mean TMA ± SD was 87.2° ± 2.4° with a range of 81.3° varus to 94.6° valgus. FMA and TMA showed significant gender differences (p < 0.01). Females showed more valgus alignment than males. The most common femoral phenotype was neutral in both genders. The most common tibial phenotype was neutral in the male knees (62.8%) and valgus (41.6%) in the female knees. In males, the most frequent combination (knee phenotype) was a neutral phenotype in the femur and a neutral phenotype in the tibia (25.6%). In females, it was a neutral femoral phenotype and a valgus tibial phenotype (28.3%). 3D-reconstructed CT scans confirmed the great variability of the joint line orientation in non-osteoarthritic knees. The introduced femoral and tibial phenotypes enable the evaluation of the femoral and tibial alignment together (knee phenotypes). The variability of knee phenotypes found in this young non-osteoarthritic population clearly shows the need for a more individualized approach in TKA. III.
106 citations
TL;DR: There might be many sources of error, but caution is recommended before using this system routinely without objective verification of alignment, as the VISIONAIRE PSCB system achieved unacceptable accuracy when assessed by computer navigation.
Abstract: This investigation evaluated the Smith and Nephew VISIONAIRE patient-specific cutting block (PSCB) system for total knee arthroplasty. A consecutive series of 60 patients was recruited. Intraoperative computer navigation was used to evaluate the accuracy of the cutting blocks in the coronal and sagittal planes for the tibia, as well as rotational plane for the femur. The PSCB would have placed 79.3% of the sample within ±3° of the preoperative plan in the coronal plane, while the rotational and sagittal alignment results within ±3° were 77.2% and 54.5% respectively. The VISIONAIRE PSCB system achieved unacceptable accuracy when assessed by computer navigation. There might be many sources of error, but caution is recommended before using this system routinely without objective verification of alignment.
100 citations
Cites methods from "The position and orientation of tot..."
...However the use of navigation as a measurement tool is well justified [24], with a reported accuracy within 1° or 1mm [25,26], superior to radiographs [27]or CT [28]....
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References
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TL;DR: A roentgenographic knee evaluation system endorsed by The Knee Society is included in this year's proceedings to encourage uniform reporting of the results of total knee arthroplasty.
Abstract: A roentgenographic knee evaluation system endorsed by The Knee Society is included in this year's proceedings to encourage uniform reporting of the results of total knee arthroplasty No rating system is ideal, but if many surgeons and centers use the same reporting system, then relative comparisons will at least become possible Agreement on a new system by many experienced surgeons and institutions with a large clinical volume represents a sacrifice because old rating system data will have to be discarded
1,838 citations
TL;DR: A functional approximation to earlier exact results is shown to have excellent agreement with the exact results and one can use it easily without intensive numerical computation.
Abstract: A method is developed to calculate the required number of subjects k in a reliability study, where reliability is measured using the intraclass correlation rho. The method is based on a functional approximation to earlier exact results. The approximation is shown to have excellent agreement with the exact results and one can use it easily without intensive numerical computation. Optimal design configurations are also discussed; for reliability values of about 40 per cent or higher, use of two or three observations per subject will minimize the total number of observations required.
1,795 citations
TL;DR: In this article, the epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and Tibial components.
Abstract: Thirty patients with isolated patellofemoral complications after total knee arthroplasty were compared with 20 patients with well functioning total knee replacements without patellofemoral complications. The epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and tibial components. The group with patellofemoral complications had excessive combined (tibial plus femoral) internal component rotation. This excessive combined internal rotation was directly proportional to the severity of the patellofemoral complication. Small amounts of combined internal rotation (1°-4°) correlated with lateral tracking and patellar tilting. Moderate combined internal rotation (3°-8°) correlated with patellar subluxation. Large amounts of combined internal rotational (7°-17°) correlated with early patellar dislocation or late patellar prosthesis failure. The control group was in combined external rotation (10°-0°). The direct correlation of combined (femoral and tibial) internal component rotation to the severity of the patellofemoral complication suggests that internal component rotation may be the predominant cause of patellofemoral complications in patients with normal axial alignment. The epicondylar axis and tibial tubercle are reproducible landmarks which are visible on computed tomography scans and can be used intraoperatively. Using this computed tomography study can determine whether rotational malalignment is present and thus, whether revision of one or both components may be indicated.
975 citations
TL;DR: The posterior condylar angle, referenced from the surgical epicondylar axis, provides a visual rotational alignment check during primary arthroplasty and may improve alignment of the femoral component at revision.
Abstract: The posterior condylar surfaces of the femur are routinely used as the reference for the rotational orientation of the femoral component during most primary total knee arthroplasties. The purpose of this investigation was to identify a clearly discernible, reproducible secondary anatomic axis useful for determining the rotational orientation of the femoral component when the posterior condylar surfaces cannot be used. Seventy-five embalmed anatomic specimen femurs were studied. A surgical epicondylar axis was defined as the line connecting the lateral epicondylar prominence and the medial sulcus of the medial epicondyle
805 citations
TL;DR: Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique, and potential benefits in the long-term outcome and functional improvement require further investigation.
Abstract: Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty (TKA). Recent developments in computer-assisted surgery have focused on systems for improving TKA. In a prospective study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films. The mechanical axis of the leg was significantly better in the computer-assisted group (96%, within ±3° varus/valgus) compared with the conventional group (78%, within ±3° varus/valgus). The coronal alignment of the femoral component was also more accurate in the computer-assisted group. Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.
695 citations