Effect of individualized distal femoral valgus resection angle in primary total knee arthroplasty: A systematic review and meta-analysis involving 1300 subjects

Alignment in Total Knee Arthroplasty: Avoid Crossing Over From Varus to Valgus

BACKGROUND

Ideal target limb alignment remains a debated topic in total knee arthroplasty (TKA). We aimed to determine the effect of limb alignment correction on patient-reported outcomes and knee range of motion (ROM) following TKA.

METHODS

In this retrospective analysis, patients (N = 409) undergoing primary TKA at a single institution were studied. Using full leg-length radiographs, limb alignment was measured preoperatively and postoperatively. Patients were categorized by preoperative (Preop) alignment (varus > 0°; valgus < 0°). Preop varus patients were then divided as follows based on postoperative alignment: neutral (VAR-NEUT, 0°± 2), remaining in varus (VAR-rVAR, ≥3°), and cross-over to valgus (VAR-CO, ≤-3°). Similarly, Preop valgus patients were divided as follows for postoperative alignment: neutral (VAL-NEUT, 0°± 2), remaining in valgus (VAL-rVAL, ≤-3°), and cross-over to varus (VAL-CO, ≥3°). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement survey scores were collected at preoperatively as well as at 6 weeks, 3, 6, and 12 months postoperatively. Knee ROM was collected at 2 weeks, 6 to 12 weeks, and >6 months postoperatively. An analysis of variance repeated on time followed by a Bonferroni post hoc test was used to compare outcomes for the postoperative alignment subgroups.

RESULTS

Preop Varus patients: Those in the VAR-CO group (overcorrected to -4.03° ± 1.95valgus) were observed to have lower Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores at 3, 6, and 12 months postoperatively compared to those in the NEUT group (P < .05). This finding was paired with reduced ROM at 6 to 12 weeks postoperatively in the VAR-CO group compared to VAR-NEUT and VAR-rVAR (P < .05). Preop Valgus patients: Those in the VAL-rVal group (left in -4.39° ± 1.39valgus) were observed to have reduced knee flexion at 6 to 12 weeks postoperatively compared to VAL-NEUT and VAL-CO.

CONCLUSIONS

These findings indicate that postoperative valgus alignment via either crossing over to valgus (VAR-CO) or remaining in valgus (VAL-rVAL) alignment may result in less preferable outcomes than correction to neutral or slightly varus alignment.

Superiority of kinematic alignment over mechanical alignment in total knee arthroplasty during medium- to long-term follow-up: A meta-analysis and trial sequential analysis

PURPOSE

To compare and determine the reliability and conclusiveness of the medium- and long-term efficacy in terms of patient-reported outcome measures and the risk of revisions or reoperations (RRRs) of kinematic alignment (KA) and mechanical alignment (MA) in total knee arthroplasty.

METHODS

A comprehensive search was conducted in Medline, EMBASE, Web of Science and Cochrane Database Library to identify relevant literature. Only randomised clinical trials (RCTs) published before July 2023 were included. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), Forgotten Joint Score (FJS) and RRR were compared. Additionally, OKS and RRR were subjected to a trial sequential analysis.

RESULTS

Seven RCTs involving 572 knees were identified. The pooled analysis of the included studies demonstrated that KA showed better medium-term WOMAC and OKS (mean difference [MD] = -6.3, 95% confidence interval [CI]: -9.52 to -2.99, p < 0.05 and MD = 1.1, 95% CI: 0.05-2.15, p < 0.05), respectively), but no significant differences were observed in the long-term follow-up (MD = 2.1, 95% CI: -3.21 to 7.31, not significant [n.s.] and MD = 0.01, 95% CI: -2.43 to 2.46, n.s., respectively). FJS (standardised MD = -0.03, 95% CI: -0.25 to 0.19, n.s.) and RRR (risk ratio = 1.0, 95% CI: 0.57 to 1.74, n.s.) showed no significant intergroup differences (n.s.). The evidence quality ranged from moderate to high, and the trial sequential analysis indicated the need for additional high-quality RCTs to draw more conclusive results.

CONCLUSIONS

KA showed better medium-term WOMAC and OKS, while KA and MA had similar FJS without increasing the RRR in medium- and long-term follow-up. Further research is needed for more conclusive results.

LEVEL OF EVIDENCE

Level II (meta-analyses).

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

PURPOSE

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.

METHODS

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.

RESULTS

In total, 379 primary TKA cases were evaluated. The mean time of follow-up was 12.9 years (range 10.3-15.9 years, SD = 1.8). Nine out of 379 cases were revised due to aseptic loosening; the mean time to revision was 5.5 years (range 1.0-15.5 years, 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).

CONCLUSIONS

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.

LEVEL OF EVIDENCE

III.

Femoral Valgus Correction Angle for the Intramedullary Alignment Rod Is Strongly Associated with Femoral Lateral Bowing in Japanese Patients with Varus Knee Osteoarthritis Undergoing Total Knee Arthroplasty

Background. This study aimed to investigate factors, such as differences in femoral shape, that could affect the femoral valgus correction angle (VCA) for the intramedullary alignment rod (IM rod) by using a three-dimensional (3D) measurement system in patients with varus knee osteoarthritis undergoing total knee arthroplasty (TKA). Methods. A total of 305 knees in 233 Japanese patients with varus knee osteoarthritis who underwent primary TKA by using Jig Engaged 3D Pre-Operative Planning Software for the TKA operation support system was examined. We retrospectively analysed factors, such as the shape of the proximal, middle, and distal femur in the coronal plane, all of which could affect the VCA for the IM rod, by multiple linear regression analyses. Results. The VCA for the IM rod was 5.9° ± 1.6° (range: 1.7° to 10.7°), and the femoral lateral bowing angle (FBA) was 3.5° ± 3.2°. Major factors independently associated with the VCA for the IM rod were the FBA (β: 0.75), femoral offset (β: 0.38), and the medial angle between the mechanical femoral axis and the line that connects the distal margins of the medial and lateral femoral condyles (β: −0.16). The model was created by stepwise multiple linear regression (F = 266.6, $p<0.001$ , and estimated effect size = 4.4) explained 85% of the variance in the VCA for the IM rod (R2 = 0.85). Conclusions. The VCA for the IM rod was most strongly associated with femoral lateral bowing in patients with varus knee osteoarthritis undergoing TKA. Our findings suggest that preoperatively measuring the VCA for the IM rod in patients with femoral lateral bowing by using a 3D measurement system could be useful for accurate coronal alignment of the femoral component in TKA.

Angular accuracy of plain radiographic measurements in leg alignment: Teleoroentgenogram versus orthoroentgenogram

BACKGROUND

The purpose of the present study was to evaluate the accuracy of the measurements associated with leg alignment on a teleoroentgenogram and an orthoroentgenogram.

METHODS

The models being irradiated were manufactured and represented 10° varus and 15° varus leg alignment, in which the true values of hip-knee-ankle angle (HKAA), mechanical axis (MA) length, and percentage of MA (%MA) were already known. HKAA, MA length, and %MA were measured in various radiographic conditions of the teleoroentgenogram and orthoroentgenogram. Then, the differences between the radiographic measurement values and the corresponding true values were analyzed.

RESULTS

Regarding HKAA, the teleoroentgenogram provided accurate angular measurements with minimal differences between the measurement and true value in both the 10° and 15° varus models, irrespective of the radiographic condition. In the orthoroentgenogram, the modified method measured accurate HKAA; however, the standard method showed significant angular measurement errors with a 0.6° and 1.0° difference from the true value in the 10° and 15° varus models, respectively. This angular measurement error of HKAA in the standard orthoroentgenogram became significantly larger with object-to-image distance. Regarding MA length, the orthoroentgenogram exhibited accurate length measurements. In contrast, the teleoroentgenogram showed a significant length measurement error for the MA length. Regarding %MA, significant differences from the true values of 2.0% and 2.4% were observed in the modified orthoroentgenograms of the 10° and 15° varus models, respectively. The teleoroentgenogram and standard orthoroentgenogram reproduced the accurate measurement value of %MA in the 10° and 15° varus models.

CONCLUSION

A teleoroentgenogram is a reliable modality for accurate angular measurements such as HKAA and %MA. An orthoroentgenogram has the potential to measure both HKAA and length accurately if the radiographic condition was modified; however, measurement error in %MA may occur.

Distal femoral phenotypes in Asian varus osteoarthritic knees

PURPOSE

There has been a general consensus regarding the varus phenotype of the proximal tibia in osteoarthritic patients with varus knee alignment of the whole limb. However, a valgus phenotype of the distal femur may occur in osteoarthritic patients with varus knee alignment. This study evaluated the distal femur phenotype in varus osteoarthritic knees.

METHODS

This study included 128 patients who underwent primary total knee arthroplasty (TKA) by computer-assisted navigation for primary medial osteoarthrosis with varus knee alignment. The hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and joint line convergence angle (JLCA) were measured on which radiographs preoperatively. The radiographic parameters were compared between groups with HKA angle varus ≥ 10° and < 10°.

RESULTS

The MPTA was significantly lower (4°) in the HKA angle varus ≥ 10° group than in the < 10° group (82.13° vs. 86.13° P = 0.001), but the LDFA did not differ significantly between the groups (89.81° vs. 89.19° P = 0.181). Regarding the JLCA, the varus ≥ 10° group showed a 1.3° greater lateral widening than the varus < 10° group (4.87 vs. 3.56, P = 0.002). The MPTA was the only independent predictor of the MA of the lower limb (β =  -  0.353, P < 0.001).

CONCLUSION

One-third of varus osteoarthritic knees had a distal femur valgus phenotype. Varus knee alignment was mainly affected by proximal tibia varus rather than by distal femur varus.

LEVEL OF EVIDENCE

Level III, consecutive case series.

Factors Influencing the Valgus Cut Angle-during Total Knee Arthroplasty-in Indian Population

The number of total knee arthroplasties performed in India and the world is increasing exponentially. The valgus cut angle (VCA) of the distal femur decides the final alignment achieved in the coronal plane. Little data are available regarding the ideal value for an Indian population and there is little consensus whether to use a single value for all knees or to individualize the angle for each patient. The parameters that can influence the value of this angle have not been evaluated thoroughly.Standard long leg X-ray (orthoscanogram) was used to calculate the VCA in 302 lower limbs (160 patients). Only Indian patients were included in the study; knees with bowed femurs were excluded. VCA, femoral length, medial hip offset, neck shaft angle, and hip knee ankle angle were measured manually. Demographic data such as gender, height, and weight were extracted from hospital charts. The correlation of VCA with the various parameters was evaluated using Pearson's correlation and its significance assessed using the independent Student's 't' test.The average VCA was 7.4 degrees (range: 4-11 degrees). Age, gender, height, hip knee ankle angle (alignment) and body mass index (BMI) had no influence on the VCA. The neck shaft angle (r = -0.520, p = < 0.0001) and hip medial offset (r = 0.223, p = < 0.0001) were the only two parameters significantly and independently influencing the value of VCA. There is a wide variation in the value of VCA in the Indian population. Choosing a fixed VCA will lead to significant number of knees aligned outside the ideal 0- to 3-degree hip knee ankle angle. The neck shaft angle and the medial hip offset are the only two factors that influence the VCA. The patients' height, preoperative deformity, gender, and BMI had no influence on the VCA.

Incidence of Soft-Tissue Releases, Clinical and Radiological Outcomes of Lateral Parapatellar Approach for Valgus Arthritic Knees: A 4-year Follow-up Study with A Review of Literature

PURPOSE

To analyse the incidence of additional soft tissue releases with the lateral parapatellar approach, and the clinical and radiological outcomes of total knee arthroplasties performed using the lateral parapatellar approach for valgus arthritic knees. A review of the existing literature on valgus arthritic knees undergoing knee replacement was performed and our results compared.

MATERIALS AND METHODS

This is a prospective cohort study of 50 patients operated by this approach. Operation and clinical records were assessed to determine the number and sequence of soft tissue releases. Functional outcome was measured using the Oxford Knee Score. Radiological assessment included measurement of alignment and implant positioning.

RESULTS

46 patients included. Mean follow-up of 4 years. Additional lateral releases were performed in 11 (24%) cases. Mean valgus alignment corrected from 13.1 degrees pre-operatively to 5.7 degrees post-operatively. Oxford Knee Score improved from a mean pre-operative score of 11.9 to a mean post-operative score of 38.3 at final follow-up. Radiographs revealed lateralisation of the tibial component in 4 patients. No immediate or late post-operative wound complications, late instabilities or revisions were observed.

CONCLUSION

Lateral parapatellar approach is highly effective in correcting the valgus deformity with a low incidence of additional soft tissue releases. Medium-term results indicate an excellent functional outcome with no complications.

The application of 3D printing patient specific instrumentation model in total knee arthroplasty

The application of 3D printing patient specific instrumentation model in total knee arthroplasty was explored to improve the operative accuracy and safety of artificial total knee arthroplasty. In this study, a total of 52 patients who need knee replacement were selected as the study objects, and 52 patients were divided into experimental group and control group. First, the femoral mechanical-anatomical angle (FMAA), lateral femoral angle (LFA), hip-knee-ankle angle (HKA), femorotibial angle (FTA) of research objects in both groups were measured. Then, the blood loss during the operations, drainage volume after operations, total blood loss, hidden blood loss, and hemoglobin decrease of the experiment group and the control group were measured and calculated. Finally, the postoperative outcomes of patients who underwent total knee arthroplasty were evaluated. The results showed that before the operations, in the PSI group, the femoral mechanical-anatomical angle (FMAA) was (6.9 ± 2.4)°, the lateral femoral angle (LFA) was (82.4 ± 1.6)°, the hip-knee-ankle angle (HKA) was (166.4 ± 1.4)°, and the femorotibial angle (FTA) was (179.5 ± 7.3)°. In the CON group, the FMAA was (5.8 ± 2.4)°, the LFA was (81.3 ± 2.1)°, the HKA was (169.5 ± 1.9)°, and the FTA was (185.4 ± 5.4)°. The differences in these data between the two groups were not statistically significant (P > 0.05). After the operations, in the PSI group, the total blood loss, the hidden blood loss, and the hemoglobin (Hb) decrease were respectively (420.2 ± 210.5), (240.5 ± 234.5), and (1.7 ± 0.9); in the CON group, the total blood loss, the hidden blood loss, and the Hb decrease were respectively (782.1 ± 340.4), (450.9 ± 352.6), and (2.9 ± 1.0). These data of both groups were statistically significant (P < 0.05). Therefore, it can be seen that the 3D printing patient specific instrumentation model can effectively simulate the lower limb coronal force line and was highly consistent of the preoperative software simulation plan. In addition, the random interviews of patients who underwent total knee arthroplasty showed that the knees of patients had recovered well. The application of 3D printing patient specific instrumentation model in artificial total knee arthroplasty can effectively improve the operative accuracy and safety, and the clinical therapeutic effects were significant.