Preoperative Measurement of Tibial Resection in Total Knee Arthroplasty Improves Accuracy of Postoperative Limb Alignment Restoration

Alignment analysis of Brainlab knee 3 navigation-guided total knee arthroplasty using the adjusted mechanical method

Purpose

With the application of navigation technology in Total Knee Arthroplasty (TKA), TKA procedures have become various. Studies have shown that navigation can improve the alignment of patients' lower limbs. To verify this conclusion, we collected the clinical data from patients who underwent Brainlab knee 3 navigation-guided TKA. Brainlab knee 3 is a completely new software that takes a different approach to address the current challenges of navigated TKA. During the procedure, we applied the Adjusted Mechanical Alignment (AMA) principle and took soft tissue balance as a priority. We aim to explore the patients’ lower limb alignment changes who underwent the Brainlab knee 3 navigation-guided TKA using the AMA method.

Methods

Fifty consecutive patients who underwent total knee arthroplasty using the Brainlab knee3 knee navigation system (Smith&Nephew) from January to August 2021 by the same doctor (Yunsu Chen) in the Department of Joint Surgery of the Shanghai Sixth People's Hospital were included. Hip-Knee-Ankle Angle (HKAA), anatomic Femur Tibia Angle (FTA), Lateral Distal Femoral Angle (LDFA), and medial proximal tibia angle (MPTA) were measured on preoperative and postoperative full-length lower-limbs x-ray films or weight-bearing anterior and lateral knee radiographs for observational and descriptive study. The preoperative and postoperative knee alignment changes were analyzed through paired t-test or nonparametric Wilcoxon test using SPSS 25.0 software

Results

Pre-operative and post-operative HKAA both obeyed normal distribution. The mean preoperative HKAA was 169.8° (154.9–178.7°) with a standard deviation of 5.41; the postoperative HKAA was 175.7° (168.4–180.0°) with a standard deviation of 2.81. Using the two-sample paired t-test to analyze, the result showed P = 0.000 < 0.05; a statistically significant difference exists. The preoperative and postoperative FTA obeyed normal distribution as well. The mean preoperative FTA was 174.7° (163.4–179.9°) with a standard deviation of 3.90; postoperative 175.6° (167.0–179.9°) with a standard deviation of 2.77. Using the two-sample paired t-test to analyze, the result showed P = 0.140 > 0.05, the difference was not statistically significant. The preoperative LDFA was normally distributed, while postoperative LDFA was not. The mean preoperative LDFA was 90.7° (83.5–99.6°) with a standard deviation of 3.83; the median of postoperative LDFA was 91.6° (86.0–103.2°) with an interquartile range of 2.93. Using the two-sample paired Wilcoxon test, the result showed P = 0.052 > 0.05; the difference was not statistically significant. Preoperative MPTA obeyed normal distribution, while postoperative MPTA did not. The mean preoperative MPTA was 83.5° (72.7–92.9°), with a standard deviation of 3.66; the median of postoperative MPTA was 89.3° (84.6–95.6°), with an interquartile range of 1.45. Using the two-sample paired Wilcoxon test, the result shows P = 0.000 < 0.05; a statistically significant difference exists.

Conclusion

In our study, AMA alignment was applied in Brainlab Knee3 computer navigation-assisted total knee arthroplasty. The femoral and tibial osteotomy angles were minimally adjusted according to soft tissue situations to reduce soft tissue release. We found AMA alignment provides good control of knee alignment in the coronal plane of the lower limbs, which is a reliable technique.

Achieving coronal plane alignment in total knee arthroplasty through modified preoperative planning based on long-leg radiographs: a prospective study

Purpose

This prospective study was undertaken to examine whether the desired coronal plane alignment of limb and prosthetic components in total knee arthroplasty (TKA) could be achieved precisely using conventional jig-based methods by modifying the preoperative planning of bone resection utilizing long-leg radiographs (LLRs).

Methods

The study included consecutive 245 TKA procedures. Pre- and postoperative radiological variables, i.e., the mechanical axis (hip-knee-ankle [HKA] axis), mechanical lateral distal femoral angle (mLDFA), and medial proximal tibial angle (MPTA), and their outliers were evaluated. Statistical analysis was performed using SPSS version 21.0.

Results

The mean postoperative HKA axis, mLDFA and MPTA was 179.80 ± 1.81° (p < 0.01; 95% CI: 8.09–9.67), 90.35 ± 1.54° (p < 0.01; 95% CI: 1.33–2.02), and 90.26 ± 1.25° (p < 0.01; 95% CI: 4.41–5.20), respectively. The postoperative HKA axis on the coronal plane was 180 ± 3° in 235 knees (95.92%, 4.08% outliers). Femoral and tibial components were implanted in an acceptable position, withing 90 ± 3° of the mechanical axis of the femur and tibia on the coronal plane in 238 (97.14%, 2.86% outliers) and 243 (99.18%, 0.8% outliers) knees, respectively.

Conclusion

Modified preoperative planning for TKA on LLRs is a reliable and consistent method to achieve the desired limb and component alignment on the coronal plane without adding financial or logistical costs.

Level of evidence

II

Comparison of Valgus Correction Angle between Patients with Developmental Dysplasia Hip and Normal Volunteers Measured by Three-Dimensional Reconstruction and X-Ray

Methods

Bilateral VCA of 50 DDH patients and 56 normal volunteers were measured by Mimics software in the 3D method and X-ray in 2D. Two VCA (the upper VCA and the lower VCA) were measured in both two methods. Every VCA was measured by observer A and observer B for twice separately. The statistical analyses of the differences were calculated among the measurements of the VCA.

Results

The mean value of the upper VCA measured in 3D was 4.95° ± 0.76° in DDH group and 5.56° ± 0.62° in the normal group with significant difference (t = -6.457, p < 0.01). The VCA of DDH group and normal group measured by 3D was larger than 2D, both the upper VCA and the lower VCA. The differences indicated statistically significant. The mean value of lower VCA was 0.60° smaller than the mean value of upper VCA in normal volunteers. The mean value of the lower VCA was 0.58° larger than the mean value of the upper VCA in DDH patients.

Conclusions

Compared to X-ray, 3D reconstruction technology is more accurate without conventional limitations. The lower VCA of DDH patients should be regarded as the femoral intramedullary guide angle in TKA, especially for patients with femoral deformities.

Improving Tibial Component Coronal Alignment During Total Knee Arthroplasty with the Use of a Double-Check Technique

Objective

To compare the efficacy of the restoration of tibial component coronal alignment with a double‐check technique and the conventional surgical technique during total knee arthroplasty (TKA) in knee osteoarthritis patients, and to investigate the distribution of the medial proximal tibial angle (MPTA) after TKA.

Methods

A retrospective review was performed of 151 patients (179 knees) with knee osteoarthritis undergoing primary TKA in Beijing Chaoyang Hospital, Capital Medical University from February 2013 to January 2015 to evaluate the differences in MPTA in patients undergoing the conventional TKA and those undergoing a modified TKA with a double‐check technique after the surgery. All patients were evaluated by MPTA, range of motion (ROM), Knee Society Clinical Rating System (KSS) clinical scores, and KSS functional scores. An MPTA deviation of 3° or greater was considered malalignment.

Results

A total of 130 TKA procedures in 119 patients were included in the study: 64 knees treated with conventional TKA and 66 knees treated with the double‐check technique TKA. The mean postoperative MPTA was 88.6° ± 2.2° in the conventional TKA group and 89.1° ± 1.5° in the double‐check TKA group. The mean postoperative MPTA between the two groups was not significantly different. In the conventional TKA group, 79.7% (51 knees) had a postoperative MPTA deviation within 3° and 20.3% (13 knees) had a MPTA deviation greater than 3°. In the double‐check TKA group, 93.9% (62 knees) had a postoperative MPTA deviation within 3°and 6.1% (4 knees) had a MPTA deviation greater than 3°. The postoperative MPTA deviation within 3° showed a statistically significant difference between the two groups. In the double‐check TKA group, a 21.2% (14 knees) tibial malalignment was detected after the first check and a 9.1% (6 knees) tibial malalignment was detected after the second check. The mean postoperative ROM was 118.1° ± 9.2° in the conventional TKA group and 115.7° ± 10.1° in the double‐check TKA group. The mean postoperative KSS clinical score was 89.3 ± 3.5 in the conventional TKA group and 89.0 ± 3.7 in the double‐check TKA group. The mean postoperative KSS functional score was 84.8 ± 10.0 in the conventional TKA group and 84.9 ± 9.0 in the double‐check TKA group. The mean postoperative ROM, KSS clinical scores, and KSS functional scores between the two groups were not statistically significantly different.

Conclusion

Malalignment of the tibial component can occur after conventional TKA, and the double‐check technique is an effective method to improve tibial component coronal alignment.

Measurement of proximal tibial morphology in northeast Chinese population based on three-dimensional reconstruction computer tomography

Tibial component of total knee arthroplasty (TKA) is designed according to morphology of proximal tibia to a large extent. Owing to racial difference, current design of tibial component based on Caucasian may not be suitable for Chinese patients. Meanwhile, data of proximal tibial morphology in Chinese population is lacking. The objective of this research was to investigate proximal tibial morphology of northeast Chinese population.Computer tomography (CT) image of 164 northeast Chinese participants was collected. After three-dimensional (3D) reconstruction, size of tibia plateau and TKA resected surface were gauged to guide the design of TKA tibia prothesis in northeast Chinese population. Measurement of tibial size mainly includes tibial mediolateral length (tML), tibial medial/lateral anteroposterior length (tMAP and tLAP). Afterwards, tML/tAP ratio of tibia plateau and TKA resected surface were calculated as feature point of tibia prothesis. tMAP/tLAP ratio of TKA resected surface was calculated to represent tibial asymmetry degree. Medial and lateral posterior tibial slope (MPTS and LPTS) were also measured to give reference to posterior angle of tibia prothesis and angle of tibia osteotomy in TKA. Independent sample t test was performed to conduct statistical analysis, P < .05 was regarded as statistically significance.Northeast Chinese male has larger knee size than female. Significant difference of tML/tAP ratio was also observed between male and female on tibia plateau (1.71 ± 0.07 vs 1.77 ± 0.09) but not on TKA resected surface (1.60 ± 0.05 versus 1.61 ± 0.06). Significant difference of tMAP/tLAP ratio between male and female was also found and they were 1.31 ± 1.03 and 1.11 ± 0.05 respectively. Northeast Chinese female has higher PTS than male (MPTS: 9.56 ± 2.96° vs 8.81 ± 2.87° and LPTS: 8.57 ± 3.19° vs 8.44 ± 2.76°).Significant gender-difference of tibial size and asymmetry degree of tibial resected surface were found between northeast Chinese male and female. Meanwhile, northeast Chinese population has smaller knee size, larger PTS and tML/tAP ratio than that of Caucasian population. Therefore, Chinese-specific and gender-specific tibial prostheses were strongly recommended to be designed.

Radiographic Measurement of Femoral Lateral Bowing and Distal Femoral Condyle Resection Thickness: Variances and Effects on Total Knee Arthroplasty Planning

Background:

Accurate evaluation of the plain radiography of lower limb is critical for preoperative planning of total knee arthroplasty (TKA). We aimed to investigate the effect of femoral lateral bowing and rotation on the radiographic measurements of distal femoral condyle resection thickness (DRT) and the distal femoral resection valgus angle (FVA).

Methods:

We analyzed 246 three-dimensional femoral models generated from computed tomography images of 123 patients, acquiring projected contours in seven positions – 20° and 10° internal rotation; 0° rotation; 10°, 20°, 30°, and 40° external rotation – for each model. Medial and lateral condyle DRTs, femoral shaft lateral bowing angle (FBA), and distal FVA were determined for each position. Linear mixed effect model was used to determine the effect of degree of femur rotation on repeated measurements of DRT or FVA.

Results:

FBA significantly affected the FVA and DRT (Pearson's R = 0.767 and −0.408, respectively; P < 0.000). Samples were divided into three groups according to the FBA measured in neutral position: FBA <0°: DRT 3.75 ± 1.30 mm, FVA 4.53° ± 1.27°; FBA >0° but <3°: DRT 3.39 ± 1.31 mm, FVA 5.92° ± 1.31°; FBA >3°: DRT 2.22 ± 1.31 mm, FVA 7.37° ± 1.31°. From simulated 20° internal rotation to 40° external rotation in each femoral model, the average variation ranges of radiographically measured DRT, FVA, and FBA were 0.50 ± 0.28 mm, 2.93° ± 0.96°, and 10.33° ± 1.90°, respectively, with no significant differences among the FBA groups. The degree of femoral rotation significantly affected the FVA (F = 62.148, P < 0.000), whereas there was no effect on condyle resection thickness (F = 0.4705, P = 0.494).

Conclusions:

Axial femoral rotation has less effect on radiographic measurements of differences in the DRT than on those of the distal FVA.