Prevalence and predictors of post-operative coronal alignment outliers and their association with the functional outcomes in navigated total knee arthroplasty

No consistent association between patient-reported outcome measures and coronal alignment following total knee arthroplasty: a narrative review

BACKGROUND

Total knee arthroplasty is a common procedure for treating knee conditions; however, significant proportions of patients report dissatisfaction post-operatively. Recent data suggests accurate coronal alignment may not be essential for optimizing prosthesis functionality and survivorship. This narrative review utilized a systematic approach to analyse the literature comparing post-operative coronal alignment and PROMs following knee replacement.

METHODS

A systematic search of MEDLINE was utilized to identify publications that directly compare the relationship between coronal alignment and PROMs.

RESULTS

Thirty-one eligible publications were identified. Variability in both study design and findings were observed, with no studies being without risk of bias.

CONCLUSION

Given this variability and lack of consensus among the reported publications, current literature is ill-equipped to describe the exact nature of the relationship between coronal alignment and PROMs following TKA. Further research would ideally utilize both validated generic, and knee-specific PROMs, make use of pre-operative outcome data, and standardized follow-up to develop reliable assessments of coronal alignment and its impact upon both functionality and quality of life.

Extramedullary Guide Alignment Is not Affected by Obesity in Primary Total Knee Arthroplasty

Coronal alignment of the tibial implant correlates with survivorship of total knee arthroplasty (TKA), especially in obese patients. The purpose of this study was to determine if obesity affects coronal plane alignment of the tibial component when utilizing standard extramedullary tibial guide instrumentation during primary TKA. A retrospective review from June 2017 to February 2018 identified 142 patients (162 primary TKAs). There were 88 patients (100 knees) with body mass index (BMI) < 35 kg/m² and 54 patients (62 knees) with BMI ≥ 35.0 kg/m². The cohorts did not differ in age (p = 0.37), gender (p = 0.61), or Charlson's comorbidity index (p = 0.54). Four independent reviewers measured the angle between the base of the tibial component and the mechanical axis of the tibia on the anteroposterior view of long-leg film at first postoperative clinic visit. Outliers were defined as patients with greater than 5 degrees of varus or valgus alignment (n = 0). Reoperations and complications were recorded to 90 days postoperatively. There was no significant difference in mean tibial coronal alignment between the two groups (control alignment 90.8 ± 1.2 degree versus obese alignment 90.8 ± 1.2 degree, p = 0.91). There was no difference in varus versus valgus alignment (p = 0.19). There was no difference in the number of outliers (two in each group, p = 0.73). There was no difference in rate of reoperation (p = 1.0) or complication (p = 0.51). Obesity did not affect coronal plane alignment of the tibial component when using an extramedullary guide during primary TKA in our population.

False malalignment after computer-navigated total knee arthroplasty

BACKGROUND

Although computer navigation has improved component alignment in total knee arthroplasty (TKA), radiographic outliers are reported with a wide range in literature even using this technique. We hypothesized that the postoperative malalignment after computer-navigated TKA was partially derived from the inherent problems with two-dimensional (2D) measurement such as inaccuracies in measurement due to the knee position during the radiographic examination and the direction of the X-ray beam. We therefore conducted this study to determine how often knees with malalignment on 2D imaging were truly mal-aligned on three-dimensional (3D) reconstructed imaging.

METHODS

Sixty-two computer-navigated primary TKAs performed in 47 patients were included in this study. In all cases, a weight-bearing long-leg radiograph was obtained after TKA. 3D measurements were performed for outliers 2° or more in coronal alignment of the femoral or tibial component.

RESULTS

For the 18 femoral mal-aligned components on 2D imaging, eight (44.4%) were not truly mal-aligned on 3D imaging (P = 0.0014). For the eight tibial mal-aligned components on 2D imaging, all knees (100%) were not truly mal-aligned on 3D imaging (P < 0.0001).

CONCLUSIONS

A considerable number of the false malalignments were included on 2D measurement. Postoperative component alignment in the computer-navigated TKA might be much better than previously reported.

Tibial component coverage affects tibial bone resorption and patient-reported outcome measures for patients following total knee arthroplasty

Purpose

The aim of this study is to investigate the prognostic value of tibial component coverage (over-hang and under-hang) and the alignment of total knee arthroplasty (TKA) components 1 week after surgery. We select patient-reported outcome measures (PROMS) (the Knee Society score (KSS score) and the Western Ontario and McMaster Universities Osteoarthritis Index-pain score (WOMAC pain score)) and tibial bone resorption (TBR) 2 years after surgery as the end points.

Methods

The study retrospectively analyzed 109 patients undergoing TKA (fixed-bearing prosthesis with asymmetrical tibial tray) from January 2014 to December 2017 in Huashan Hospital. By using standard long-leg X-rays, anteroposterior (AP) and lateral X-rays of the knee, tibial component coverage (under-hang or over-hang), AP tibial-femoral anatomical angle (AP-TFA), AP femoral angle (AP-FA), AP tibial angle (AP-TA), and lateral tibial angle (L-TA) were measured at 1 week after surgery, while TBR was measured through postoperative 1-week and 2-year AP and lateral radiographs of the knee on three sides (medial side, lateral side on AP radiograph, and anterior side on lateral radiograph). The Pearson correlation analysis, simple linear regression, multiple linear regression, the Student’s t test, and one-way ANOVA together with Tukey’s post hoc test (or Games-Howell post hoc test) were used in the analyses.

Results

Tibial under-hang was more likely to appear in our patients following TKA (42%, medially, 39%, laterally, and 25%, anteriorly). In multivariate linear regression analysis of TBR, tibial under-hang (negative value) 1 week after surgery was positively correlated with TBR 2 years later on the medial (p = 0.003) and lateral (p = 0.026) side. Tibial over-hang (positive value) 1 week after surgery on the medial side was found negatively related with KSS score (p = 0.004) and positively related with WOMAC pain score (p = 0.036) 2 years later in multivariate linear regression analysis of PROMS. Both scores were better in the anatomically sized group than in the mild over-hang group (or severe over-hang) (p < 0.001). However, no significant relationship was found between the alignment of TKA components at 1 week after surgery and the end points (TBR and PROMS) 2 years later.

Conclusion

Under-hang of the tibial component on both the medial and lateral sides can increase the risk of TBR 2 years later. Over-hang of tibial component on the medial side decreases the PROMS (KSS score and WOMAC pain score) 2 years later. An appropriate size of tibial component during TKA is extremely important for patient’s prognosis, while the alignment of components might not be as important.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02250-7.

How to predict early clinical outcomes and evaluate the quality of primary total knee arthroplasty: a new scoring system based on lower-extremity angles of alignment

Background

A method that can accurately predict the outcome of surgery can give patients timely feedback. In addition, to some extent, an objective evaluation method can help the surgeon quickly summarize the patient’s surgical experience and lessen dependence on the long wait for follow-up results. However, there was still no precise tool to predict clinical outcomes of total knee arthroplasty (TKA). This study aimed to develop a scoring system to predict clinical results of TKA and then grade the quality of TKA.

Methods

We retrospectively reviewed 98 primary TKAs performed between April 2013 and March 2017 to determine predictors of clinical outcomes among lower-extremity angles of alignment. Applying multivariable linear-regression analysis, we built Models (i) and (ii) to predict detailed clinical outcomes which were evaluated using the Knee Society Score (KSS). Multivariable logistic-regression analysis was used to establish Model (iii) to predict probability of getting a good clinical outcome (PGGCO) which was evaluated by Knee Injury and Osteoarthritis Outcome Score (KOOS) score. Finally, we designed a new scoring system consisting of 3 prediction models and presented a method of grading TKA quality. Thirty primary TKAs between April and December 2017 were enrolled for external validation.

Results

We set up a scoring system consisting of 3 models. The interpretations of Model (i) and (ii) were good (R² = 0.756 and 0.764, respectively). Model (iii) displayed good discrimination, with an area under the curve (AUC) of 0.936, and good calibration according to the calibration curve. Quality of surgery was stratified as follows: “A” = PGGCO ≥0.8, “B” = PGGCO ≤0.6 but < 0.8, and “C” = PGGCO < 0.6. The scoring system performed well in external validation.

Conclusions

This study first developed a validated, evidence-based scoring system based on lower-extremity angles of alignment to predict early clinical outcomes and to objectively evaluate the quality of TKA.

Revisiting the tibial crest as reference for the mechanical alignment of the tibial component in total knee arthroplasty: a cadaveric study on Caucasian tibiae

PURPOSE

The accuracy of the tibial crest (TC) in guiding the mechanical alignment of the tibial component in total knee arthroplasty (TKA) has been investigated in a few studies on Asian patients. No study analyzed the anatomical variants of the TC. We analyzed the morphological types of the TC in cadaveric tibiae of Caucasian subjects and assessed whether the TC may be considered an accurate guide for the mechanical alignment of the tibial component in TKA.

METHODS

The TC and mechanical axis (MA) were identified in 86 dried cadaveric tibiae by placing metal landmarks along the TC course and a guidewire overlapping the MA. Coronal view radiographs were taken in different positions of tibial axial rotation, and the relationships between the TC and MA were analyzed.

RESULTS

The TC showed three different patterns, comprising a curved, mixed and straight course in 47 (54.6%), 21 (24.4%) and 18 (20.9%) tibiae, respectively. When a curved course was found, the TC intersected the MA at proximal and distal points located, on average 22.4% and 63.3% along the tibial length, respectively. When a straight course was found, the mean angle between the TC and MA was 2.9°. In 35% of the cases, the two axes differed by more than 3°.

CONCLUSION

The TC of Caucasian subjects exhibits a marked variability in its course and relationship with the MA. Unlike the TC in Asian subjects, the TC of Caucasians cannot be considered an accurate anatomical reference to guide the coronal alignment of the tibial component in TKA.

Technical and surgical causes of outliers after computer navigated total knee arthroplasty

Background

Navigated total knee arthroplasty (TKA) improves implant and limb alignment but outliers continue to exist. This study aimed to determine the technical and surgical causes of outliers.

Methods

This retrospective cohort study included 208 patients who had undergone navigated TKA. Limb and implant alignment indices were measured on post-operative CT scans: mechanical femoro-tibial angle (MFTA); coronal femoral angle (CFA); coronal tibial angle (CTA); sagittal femoral angle (SFA); and sagittal tibial angle (STA). Values outside 0°±3° for MFTA and SFA, 90°±3° for CFA, CTA and STA were considered outliers. Intra-operative navigation data and CT scans were evaluated to categorize the causes of sagittal and coronal plane outliers into hip centre error; ankle centre error; heterogeneous tibial cement mantle; malalignment accepted by surgeon; suboptimal knee balance; and no obvious explanation.

Results

Of the 1040 measurements (five per TKA), the overall incidence of outliers was 10.4% (n = 108). Femoral component outliers (CFA + SFA, n = 51) were all attributable to hip centre error. Tibial component outliers (CTA + STA, n = 43) were attributable to ankle centre error (n = 6), heterogeneous cement mantle (n = 20), malalignment accepted by the surgeon (n = 6) and no obvious cause (n = 11). MFTA outliers were attributable to hip centre error (n = 4) or suboptimal knee balance (n = 10).

Conclusions

Surgeon related errors can be minimized by a meticulous operative technique. These results indicate scope for additional technical improvement, especially in hip centre acquisition, which may further reduce the incidence of outliers.

Component Alignment in Simultaneous Bilateral versus Unilateral Total Knee Arthroplasty

Purpose

The purpose of this study was to investigate differences in component alignment between first and second knees in simultaneous bilateral total knee arthroplasty (SBTKA) and unilateral TKA (UTKA).

Materials and Methods

274 SBTKAs and 198 UTKAs were included in study. Patients were divided into three groups as SBTKA on the right knee (group A), SBTKA on the left knee (group B) and UTKA (group C). Femoral and tibial component alignment was checked in both coronal plane (alpha [α] and beta [β] angles) and sagittal plane (gamma [γ] and delta [δ] angles) radiographs.

Results

There were no statistically significant differences among groups in the preoperative anatomical varus angle and Kellgren–Lawrence gonarthrosis classification grade (p=0.139 and p=0.329, respectively). In the coronal plane, the alignment of femoral component (α angle) and tibial component (β angle) was similar in all three groups (α angle, 95.01 vs. 95.14 vs. 94.9, p=0.945; β angle, 90.03 vs. 89.67 vs. 89.98, p=0.483). The sagittal plane alignment of femoral component (γ angle) and tibial component (δ angle) did not show significant differences (γ angle, 7.04 vs. 6.98 vs. 7.00, p=0.132; δ angle, 86.56 vs. 87.41 vs. 86.73, p=0.610).

Conclusions

The angular alignment of components was similar between SBTKA and UTKA.

Extra-articular deformities in arthritic knees-a grueling challenge for arthroplasty surgeons: An evidence-based update

Critical to the success of a total knee arthroplasty (TKA) is the anatomical alignment. This may appear as a challenge in an extra-articular deformity (EAD) that may be inherent in certain people or result from fracture malunion, congenital disorders, nutritional, metabolic and infective causes. This appraisal aimed at providing the reader with an up-todate overview of the research carried out on, and existent evidence of EAD correction while planning a TKA. We reviewed the current English literature on TKA in extra-articular knee deformities. Among the published data, a common initial approach of mandatory clinical and radiological assessment emerges as an obligatory step while handling cases with EAD. While several methods of managing the deformity and arthritis have been described, a broad division into intra-articular and extra-articular means can be deciphered. The relatively old-school, yet reliable thought process of extra-articular correction allows an all-inclusive restoration of alignment with the inherent complications related to the necessary osteotomy. A cohort of younger and more venturesome surgeons seem inclined towards performing navigated, intra-articular correction for mild to moderate and sometimes, severe deformities. The crux of the matter lies is obtaining a well-balanced knee without violating the all-important cruciates. Restoring the patient’s ambulatory status seems sooner with the intra-articular methods which are also more precise in determining the axes and while removing minimum bone. Greatest satisfaction is accomplished in those with less grotesque, rotationallyaligned knees while meticulously balancing soft-tissues and encouraging earlier weightbearing.

Does post-operative knee awareness differ between knees in bilateral simultaneous total knee arthroplasty? Predictors of high or low knee awareness

PURPOSE

To evaluate the difference in post-operative knee awareness between knees in patients undergoing bilateral simultaneous total knee arthroplasty (TKA) and to assess factors predicting high or low knee awareness.

METHODS

This study was conducted on 99 bilateral simultaneous TKAs performed at our institution from 2008 to 2012. All patients received one set of questionnaires [Forgotten Joint Score (FJS) and Oxford Knee Score (OKS)] for each knee. Based on the FJS, the patients' knees were divided into two groups: "best" and "worst" knees. The median of the absolute difference in FJS and OKS within each patient was calculated. Multivariate linear regression was performed to identify factors affecting FJS.

RESULTS

The difference between knees was 1 point (CI 0-5) for the FJS and 1 point (CI 0-2) for the OKS. The FJS for females increased (decreasing awareness) with increasing age. Males had the highest FJS (lowest awareness) at the age of 67. An increase in the FJS (lower knee awareness) of 12.0 points was found for Kellgren-Lawrence (K-L) grades 3 + 4 compared with K-L grades 1 + 2. A preoperative anatomical alignment of 3° valgus resulted in the lowest FJS (highest knee awareness) with decreasing knee awareness for decreasing tibio-femoral angles. Post-operative alignment did not significantly affect FJS.

CONCLUSION

Knee awareness did not differ significantly between the "best" and the "worst" knee. Bilateral simultaneous TKA can be performed without compromising the result in one of the knees. Knee awareness after primary TKA was influenced by age, gender, preoperative knee alignment, and severity of OA.

LEVEL OF EVIDENCE

III.

Clinical outcome is not affected by total knee arthroplasty alignment

PURPOSE

This study aims to analyse the influence on total knee arthroplasty (TKA) clinical outcomes of biomechanical intra-operative computer-assisted surgery-measured parameters, together with radiographic and demographical data.

METHODS

Between 2007 and 2009, 227 computer-assisted surgery (CAS) primary TKAs were performed in 219 consecutive patients. Information about gender, age and body mass index (BMI) was collected for each patient. Before knee replacement, all patients underwent a complete radiographic examination and passive flexion-extension range of motion was recorded. All TKAs were implanted using an image-free knee navigation system. Patients included in the study were evaluated at 3, 6 and 12 months of follow-up and then yearly. At each follow-up, subjects were asked to answer the validated Italian version of the Knee Injury and Osteoarthritis Outcome Score.

RESULTS

One hundred and eighty patients (187 knees) had data available for analysis. Complications were reported in 13 patients (7.0 %). Intra-operative CAS-measured parameters, together with age, BMI, gender, pre- and post-operative radiographic alignment, did not influence TKA clinical results at a mean 2 years of follow-up. On the other hand, higher post-operative flexion arc of movement was suggestive of better clinical outcomes.

CONCLUSION

TKA clinical outcome is influenced by post-operative knee flexion, other than neutral mechanical limb alignment. Therefore, it is recommended to prefer TKA designs that allow high flexion and to encourage early physical rehabilitation.

LEVEL OF EVIDENCE

IV.