Effect of distance between the feet on knee joint line orientation after total knee arthroplasty in standing full-limb radiographs

Fully automated assessment of the knee alignment on long leg radiographs following corrective knee osteotomies in patients with valgus or varus deformities

INTRODUCTION

The assessment of the knee alignment on long leg radiographs (LLR) postoperative to corrective knee osteotomies (CKOs) is highly dependent on the reader's expertise. Artificial Intelligence (AI) algorithms may help automate and standardise this process. The study aimed to analyse the reliability of an AI-algorithm for the evaluation of LLRs following CKOs.

MATERIALS AND METHODS

In this study, we analysed a validation cohort of 110 postoperative LLRs from 102 patients. All patients underwent CKO, including distal femoral (DFO), high tibial (HTO) and bilevel osteotomies. The agreement between manual measurements and the AI-algorithm was assessed for the mechanical axis deviation (MAD), hip knee ankle angle (HKA), anatomical-mechanical-axis-angle (AMA), joint line convergence angle (JLCA), mechanical lateral proximal femur angle (mLPFA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibia angle (mMPTA) and mechanical lateral distal tibia angle (mLDTA), using the intra-class-correlation (ICC) coefficient between the readers, each reader and the AI and the mean of the manual reads and the AI-algorithm and Bland-Altman Plots between the manual reads and the AI software for the MAD, HKA, mLDFA and mMPTA.

RESULTS

In the validation cohort, the AI software showed excellent agreement with the manual reads (ICC: 0.81-0.99). The agreement between the readers (Inter-rater) showed excellent correlations (ICC: 0.95-0. The mean difference in the DFO group for the MAD, HKA, mLDFA and mMPTA were 0.50 mm, - 0.12°, 0.55° and 0.15°. In the HTO group the mean difference for the MAD, HKA, mLDFA and mMPTA were 0.36 mm, - 0.17°, 0.57° and 0.08°, respectively. Reliable outputs were generated in 95.4% of the validation cohort.

CONCLUSION

 he application of AI-algorithms for the assessment of lower limb alignment on LLRs following CKOs shows reliable and accurate results.

LEVEL OF EVIDENCE

Diagnostic Level III.

Age and sex differences in coronal lower extremity alignment in a healthy Asian population

BACKGROUND

The purpose of this study was to analyze the coronal alignment of lower extremities according to age and sex in a healthy population and demonstrate the differences.

METHODS

Standing full-lower limb anteroposterior (AP) radiographs of healthy volunteers (670 males and 782 females) aged 18-69 years were retrospectively analyzed. The hip-knee-ankle angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), joint line convergence angle and femoral bowing angle (FBA) were measured. The radiographic parameters were compared according to groups of age and sex. The proportion of volunteers with varus or valgus alignment more than 3° were also analyzed.

RESULTS

With increasing age, HKA and LDFA varus increased. With increasing age, femoral medial bowing decreased. In addition, the HKA showed more varus alignment in males than in females (178.01° vs. 178.82°, P < 0.001). The MPTA was about 1° smaller in males than in females (P < 0.001). The proportion of patients with varus alignment of more than 3° increased with increasing age, with 16.9% in the 10-19 years old and 38.0% in the 60-69 years old groups.

CONCLUSION

This study demonstrated that males showed more varus tibial alignments than females. Varus limb alignment, LDFA, and FBA also increases with age. In contrast, tibial alignment was constant across all age groups. Therefore, differences in lower extremity alignment according to age and sex should be considered in estimating individual prearthritic alignments.

Clinical relevance of joint line obliquity after high tibial osteotomy for medial knee osteoarthritis remains controversial: a systematic review

PURPOSE

To systematically review the literature on the association between knee joint line obliquity (KJLO) and clinical outcome after high tibial osteotomy (HTO) for medial knee osteoarthritis and summarize the KJLO cut-off value used when studying this association.

METHODS

A systematic search was conducted in three databases (PubMed, Embase, and Web of Science) on September 2022, updated on February 2023. Eligible studies describing postoperative KJLO in relation to clinical outcome after HTO for medial knee osteoarthritis were included. Nonpatient studies and conference abstracts without full-text were excluded. Two independent reviewers assessed title, abstract and full-text based on the inclusion and exclusion criteria. The modified Downs and Black checklist was used to assess the methodological quality of each included study.

RESULTS

Of the seventeen studies included, three had good methodological quality, thirteen fair quality, and one had poor quality. Conflicting findings were shown on the associations between postoperative KJLO and patient-reported outcome, medial knee cartilage regeneration, and 10-year surgical survival in sixteen studies. Three good-quality studies found no significant differences in lateral knee cartilage degeneration between postoperative medial proximal tibial angle > 95° and < 95°. Joint line orientation angles by the tibial plateau of 4° and 6°, joint line orientation angle by the middle knee joint space of 5°, medial proximal tibial angles of 95° and 98°, and Mikulicz joint line angle of 94° were KJLO cut-off values used in the included studies.

CONCLUSION

Based on current evidence, the actual association between postoperative KJLO and clinical consequences after HTO for medial knee osteoarthritis cannot be ascertained. The clinical relevance of KJLO after HTO remains controversial.

LEVEL OF EVIDENCE

IV.

Assessment of joint line obliquity and its related frontal deformity using long-standing radiographs

Purpose

To investigate how radiographic techniques and osteoarthritis grade influence measurements of knee joint line obliquity (KJLO) and KJLO-related frontal deformity, and to propose preferable KJLO measurement methods.

Methods

Forty patients with symptomatic medial knee osteoarthritis indicated for high tibial osteotomy were assessed. Measurements were compared between single-leg and double-leg standing radiographs for KJLO measurement methods including joint line orientation angle by femoral condyles (JLOAF), joint line orientation angle by middle knee joint space (JLOAM), joint line orientation angle by tibial plateau (JLOAT), Mikulicz joint line angle (MJLA) and medial proximal tibial angle (MPTA), as well as KJLO-related frontal deformity parameters including joint line convergence angle (JLCA), knee ankle joint angle (KAJA) and hip-knee-ankle angle (HKA). Influences of bipedal distance in double-leg standing and osteoarthritis grade on the above measurements were analysed. Measurement reliability was evaluated by intraclass correlation coefficient.

Results

From single-leg to double-leg standing radiographs MPTA and KAJA did not change significantly, whereas the other measurements showed significant changes: JLOAF, JLOAM and JLOAT decreased 0.88°, 1.24° and 1.77°, MJLA and JLCA decreased 0.63° and 0.85°, and HKA increased 1.11° (p < 0.05). Bipedal distance in double-leg standing radiographs moderately correlated with JLOAF, JLOAM and JLOAT (rp = -0.555, -0.574 and -0.549). Osteoarthritis grade moderately correlated with JLCA in single-leg and double-leg standing radiographs (rs = 0.518 and 0.471). All measurements had at least good reliability.

Conclusion

In long-standing radiographs, measurements of JLOAF, JLOAM, JLOAT, MJLA, JLCA and HKA are all influenced by single-leg/double-leg standing; JLOAF, JLOAM and JLOAT are also affected by bipedal distance in double-leg standing; and JLCA is affected by osteoarthritis grade. Knee joint obliquity as assessed by MPTA measurement is independent of single-leg/double-leg standing, bipedal distance or osteoarthritis grade, and has excellent measurement reliability. We therefore propose MPTA as the preferable KJLO measurement method for clinical practice and future research.

Level of evidence

III, cross-sectional study.

Latarjet procedure without capsular repair produces favorable clinical results and avoids limitation in external rotation

PURPOSE

This study aimed at analyzing the range of motion (ROM) and other clinical outcomes in patients with > 20% glenoid bone loss who underwent the Latarjet procedure with or without anterior capsule repair.

METHODS

This retrospective study included 47 patients with > 20% glenoid bone loss who underwent the classic Latarjet procedure from 2016 to 2021. Of these, 25 did not undergo capsular repair (no-capsular-repair group; group I) whereas 22 patients did (capsular-repair group; group II). The Rowe score, American Shoulder and Elbow Surgeons score, Visual Analogue Scale, ROM, recurrence, and complications were evaluated before and 3, 6, and 12 months after the surgery. A goniometer was used to measure the forward flexion and external rotation (arm adducted, 90° abducted) of both shoulders. The ROM deficit was measured as the difference from the contralateral healthy shoulder.

RESULTS

The external rotation in arm adduction at 3 and 6 months after surgery showed significantly better results in group I than group II(p = 0.002 at 3 months; p = 0.005 at 6 months). The deficit in external rotation with arm adduction was also significantly lower in group I at 3 months (p = 0.001) and 6 months (p = 0.001) after surgery. However, external rotation with arm adduction at 12 months after surgery did not significantly differ between the groups. Moreover, the ROM in external rotation with 90° arm abduction was significantly better in group I than that in group II at 3, 6, and 12 months postoperatively (p = 0.002, p = 0.001, and p = 0.005, respectively). The deficit in external rotation with 90° arm abduction gradually decreased with time after surgery and differed significantly between the groups. However, the difference in deficit between the two groups at 12 months after surgery did not exceed the measurement error. All clinical scores significantly improved after surgery compared to before surgery; however, the improvement did not significantly differ between the two groups.

CONCLUSION

The Latarjet procedure without capsular repair showed good laxity restoration and clinical results with less early postoperative external rotation limitation than that achieved by the same procedure with capsular repair. However, external rotation deficit at 1 year after surgery did not show a clinically relevant difference difference between the two groups.

LEVEL OF EVIDENCE

Level III.

Implication of Changes in the Imaging Measurements after Mechanically Aligned Total Knee Arthroplasty

OBJECTIVE

Imaging measurements allow assessment of the mechanical alignment before and after total knee arthroplasty (TKA). The changes in radiographic parameters in each period of time within 1 year after TKA has been poorly understood. The purpose of this study was to examine the timing and causes of imaging changes in lower extremity force lines after total knee arthroplasty with mechanical alignment.

METHODS

A total of 93 mechanically-aligned TKA were radiographically examined before, 3 days, 3 months, and 1 year after surgery. Radiographic parameters included hip-knee angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), knee joint line orientation (KJLO), ankle joint line orientation (AJLO), the knee joint line relative to ankle joint line angle (KJLTA) and midpoints of the ankle distance (MAD). Paired t-test were used to analyze the changes of these imaging parameters, By establishing a simple tibial model, the time points of changes in the imaging parameters after TKA was determined, with an attempt to understand the post-TKA changes in these imaging parameters.

RESULTS

Statistically significant differences were found between the preoperative data and the data measured 3 days after surgery in HKA, LDFA, MPTA, MAD, KJLTA, AJLO (P < 0.05) while KJLO exhibited no significant difference (P = 0.089). There existed significant differences between the data measured 3 days and the measurements taken 3 months after operation in HKA, MPTA, KJLTA, KJLO, AJLO (P < 0.05), whereas LDFA and MAD showed no significant difference (P > 0.05). Significant differences were revealed between the data measured 3 months and those collected 1 year after surgery in LDFA, MPTA, AJLO, KJLTA (P < 0.05) but HKA, KJLO, AJLO showed no significant differences (P > 0.05). The tibial model was made to look into the changes in postoperative imaging parameters. ΔMAD and postoperative AJLO were calculated to verify the model and hypothesis.

CONCLUSIONS

Postoperative changes in radiographic parameters and tibial models showed that the lower extremities were in an unnatural state within 1 year after TKA. The changes in the lower extremities force line were the results of the gradual adaptation of the lower extremities to TKA and the lateral swing of the extremities (3°) after surgery. Imaging data 1 year after surgery should be taken into account in the explanation of post-TKA changes in lower limb force lines.