Variations in medial and lateral slope and medial proximal tibial angle

High variability exists in 3D leg alignment analysis, but underlying principles that might lead to agreement on a universal framework could be identified: A systematic review

PURPOSE

To (1) investigate the hypothesis that there is high variability in the reported methods to derive axes and joint orientations from three-dimensional (3D) bone models to (a) perform 3D knee-related leg alignment analysis and (b) define coordinate systems for the femur, tibia and leg and (2) identify underlying principles that might lead to agreement on a universal 3D leg alignment analysis framework.

METHODS

A systematic review of the literature between January 2006 and June 2024 was performed. Articles explicitly reporting methods to derive axes and joint orientations from CT-based 3D bone models for alignment parameters and/or coordinate systems of the femur, tibia and leg were included. Study characteristics and reported methods were extracted and presented as a qualitative synthesis.

RESULTS

A total of 93 studies were included. There was high variability in the reported methods to derive axes and joint orientations from 3D bone models. Nevertheless, the reported methods could be categorized into four groups, and several underlying principles of the four groups could be identified. Furthermore, the definitions of femoral and tibial coordinate systems were most frequently based on the mechanical axis (femoral, 13/19 [68%]; tibial, 13/26 [50%]) and a central medial-lateral axis (femoral, 16/19 [84%]; tibial, 12/26 [46%]); no leg coordinate system was reported. Interestingly, of the included studies that reported on leg alignment parameters (76/93, 82%), only a minority reported expressing these in a complete coordinate system (25/76, 33%).

CONCLUSION

There is high variability in 3D knee-related leg alignment analysis. Therefore, universal 3D reference values for alignment parameters cannot yet be defined, and comparison of alignment parameter values between different studies is impossible. However, several underlying principles to the reported methods were identified, which could serve to reach more agreement on a future universal 3D framework for leg alignment analysis.

LEVEL OF EVIDENCE

Level I.

Measuring Posterior Tibial Slope: A Comparison Using a 10-cm Anatomic Axis Versus 15-cm Anatomic Axis

Background

Accurate measurement of posterior tibial slope (PTS) is for understanding knee biomechanics and stability, as well as in planning surgical procedures. The validated methodology for measuring PTS requires outline visualization of 15 cm distal to the proximal tibia, a cutoff that is not always met on standard lateral knee radiographs.

Purpose/Hypothesis

The goal of this study was to critically evaluate whether using a 10-cm anatomic axis on conventional lateral knee radiographs is comparable with the established 15-cm standard. The authors hypothesized that a shortened 10-cm anatomic axis would yield comparable results to the conventional 15-cm method.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

Lateral knee radiographs were reviewed until a cohort of 100 patients was identified where ≥15 cm of the tibial shaft distal to the joint line could be measured. PTS was calculated using both the conventional 15-cm proximal anatomic axis (15-PTS) and the proposed modified 10-cm axis (10-mPTS). Measurement reliability and agreement were quantitatively assessed via intraclass correlation coefficients (ICCs) and Bland-Altman analysis, respectively. Paired t tests and linear regression were performed to evaluate the equivalence of methods. Additionally, a second set of 100 lateral knee radiographs was randomly selected to determine a percentage of radiographs that could be measured ≥15 cm below the joint line.

Results

There was a statistically significant congruence between the 10-mPTS and 15-PTS techniques (ICC, 0.92; P < .001). The mean PTS discrepancy was statistically significant at 0.94°, with a 95% CI ranging from 0.78° to 1.0°. Both methods demonstrated high inter- and intrarater reliability (ICCs > 0.90). On 61% of standard lateral knee radiographs queried, we were unable to visualize 15 cm of the proximal tibia.

Conclusion

The 10-mPTS method exhibits <1° of deviation compared with the conventional 15-PTS approach, establishing it as a practical and reliable alternative for assessing PTS on lateral knee radiographs, particularly when visualization of 15 cm distally is not possible.

Does the posterior tibial slope in caliper-verified unrestricted kinematically aligned TKA using manual instruments match the slope in the contralateral healthy knee and improve function?

PURPOSE

Unrestricted kinematically aligned total knee arthroplasty (unKA TKA) strives to restore the pre-arthritic posterior tibial slope (PTS), however consistency of achieving this alignment target is unknown. The present study determined the proportion of subjects with differences in PTS less than 2° from the target and the improvement in patient-reported function after unKA TKA.

METHODS

A review of 562 postoperative scanograms identified 99 patients (51 female) with a unKA TKA in one limb, a contralateral healthy limb, and a postoperative axial CT scan. All patients were treated with a primary unKA TKA performed with mechanical instruments where the alignment target was setting the PTS to match that of the medial compartment of the contralateral healthy knee. The PTS of the TKA and the healthy medial tibial plateau were measured and the difference determined. The patient-reported Oxford Knee Score (OKS) measured pre- and post-operative function.

RESULTS

The proportion of subjects within a tolerance interval of ±2° of the contralateral healthy knee at 95% confidence was 85%. The median OKS improved from 20 points preoperatively to 47 points (range 18-48) at 15 months postoperatively. Greater differences of the PTS from healthy were unrelated to poorer Oxford Knee Scores.

CONCLUSION

Unrestricted KA TKA using manual instruments with caliper verification of resection thickness restored a high percentage of patients within a clinically acceptable tolerance of the posterior tibial slope of the contralateral healthy knee. The median postoperative OKS indicated clinically important improvement in patient-reported function.

Bone cysts at the meniscal attachment are associated with a longer symptom duration among patients with arthroscopically treated medial meniscus posterior root tear

PURPOSE

To elucidate the features of bone cysts at attachment sites of medial meniscus posterior root tears (MMPRTs).

METHODS

Knees treated using arthroscopic surgery for MMPRT between 2015 and 2022 were retrospectively reviewed. Patients without a memory of onset (painful popping), prior knee surgeries, concomitant ligament or meniscus injuries or fractures were excluded. Duration from onset to magnetic resonance imaging (MRI) and type of tear were evaluated during arthroscopy. On radiography, meniscus signs (cleft/ghost/giraffe neck), bone cysts at the attachment site of the MMPRT and posterior shiny-corner lesions (PSCLs; bone marrow lesions on the meniscal-covered portion of the posterior tibial plateau) were evaluated. The sensitivity and specificity of the bone cysts were assessed by comparison with matched patients who underwent arthroscopic surgery for medial meniscus posterior horn tear. In addition, subgroups (cyst-positive/cyst-negative) among patients with MMPRT were created to assess the features of bone cysts.

RESULTS

A total of 275 patients with MMPRT and 275 matched patients with posterior horn tears were evaluated. The sensitivity and specificity of bone cysts for MMPRT in this study were 22.2% and 98.6%, respectively. Among the 275 knees with MMPRT, compared with the cyst-negative group, the cyst-positive group had a longer duration from onset to MRI (12.9 ± 13.1 vs. 8.3 ± 10.9 weeks, respectively, p = 0.025) and reduced occurrence of PSCLs (18.0% vs. 42.0%, respectively, p = 0.031).

CONCLUSION

The occurrence of bone cysts at the attachment site was helpful for the accurate diagnosis of MMPRT and related to longer duration from onset to MRI and reduced PSCLs.

LEVEL OF EVIDENCE

Level III, cross-sectional study.

Artificial intelligence-based assessment of leg axis parameters shows excellent agreement with human raters: A systematic review and meta-analysis

PURPOSE

The aim of this study was to conduct a systematic review and meta-analysis on the reliability and applicability of artificial intelligence (AI)-based analysis of leg axis parameters. We hypothesized that AI-based leg axis measurements would be less time-consuming and as accurate as those performed by human raters.

METHODS

The study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO). PubMed, Epistemonikos, and Web of Science were searched up to 24 February 2024, using a BOOLEAN search strategy. Titles and abstracts of identified records were screened through a stepwise process. Data extraction and quality assessment of the included papers were followed by a frequentist meta-analysis employing a common effect/random effects model with inverse variance and the Sidik-Jonkman heterogeneity estimator.

RESULTS

A total of 13 studies encompassing 3192 patients were included in this meta-analysis. All studies compared AI-based leg axis measurements on long-leg radiographs (LLR) with those performed by human raters. The parameters hip knee ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), and joint-line convergence angle (JLCA) showed excellent agreement between AI and human raters. The AI system was approximately 3 min faster in reading standing long-leg anteroposterior radiographs (LLRs) compared with human raters.

CONCLUSION

AI-based assessment of leg axis parameters is an efficient, accurate, and time-saving procedure. The quality of AI-based assessment of the investigated parameters does not appear to be affected by the presence of implants or pathological conditions.

LEVEL OF EVIDENCE

Level I.

Comparison of coronal and sagittal alignment in patients without osteoarthritis but with knee complaints

Purpose

This study aimed to clarify lower limb alignment characteristics and the relationship between coronal and sagittal lower limb alignment in Japanese patients with knee complaints but without knee osteoarthritis (KOA).

Methods

This retrospective study included 200 knees from Japanese patients with knee complaints but without KOA aged 60 years and under presenting with knee complaints between May 2020 and May 2023. We assessed coronal parameters, including mechanical hip knee angle (mHKA), arithmetic HKA (aHKA) mechanical lateral distal femoral angle and medial proximal tibial angle (MPTA), and sagittal parameters, such as medial posterior tibial slope (MPTS) and lateral posterior tibial slope (LPTS). In addition, we compared differences between CPAK types.

Results

A weak positive correlation was found between mHKA and MPTS, but not with aHKA. Moderate negative and moderate positive correlations were found between mHKA and MPTA and between medial and LPTS, respectively.

Conclusions

Little correlation was found between the coronal and sagittal parameters in patients with knee complaints but without KOA.

Level of Evidence

Level Ⅲ.

Variability of three-dimensional knee morphology cannot be effectively assessed using a coronal plane knee alignment classification in total knee arthroplasty patients

Purpose

Optimal reproduction of the native three-dimensional (3D) alignment in total knee arthroplasty (TKA) influences outcomes; however, much of the modern TKA alignment research, such as the coronal plane alignment of the knee (CPAK), focuses only on coronal alignment. Tibial, femoral and tibiofemoral measurements on the axial and sagittal planes were evaluated for their relationship to the arithmetic hip-knee-ankle angle (aHKA) and joint-line obliquity (JLO). These 3D anatomical measurements are also evaluated across CPAK groups.

Methods

A retrospective analysis of the 360 Med Care computed tomography (CT) database was performed. Patient CT scans were segmented and landmarked. Linear regression analysis compared 12 axial and sagittal plane measurements (representing tibial, femoral and tibiofemoral rotation, tibial slope and femoral flexion) with both aHKA and JLO. Nonparametric tests assessed these anatomical measurements across the different CPAK groups, while Cohen's delta (d) determined the effect size.

Results

With a sample size of 7450 osteoarthritic knees, significant but weak relationships (r < 0.30) were observed between all 12 anatomical measurements and both aHKA and JLO. Tibiofemoral rotations between Insall's axis and both the posterior condylar and the surgical transepicondylar axes demonstrated large effect sizes (d > 0.80). However, trivial to small effect sizes (d < 0.50) were broadly observed across the 12 axial and sagittal measurements, underscoring their limited clinical significance.

Conclusions

While useful for describing coronal knee anatomy, CPAK phenotypes fail to differentiate tibial, femoral and tibiofemoral rotation, tibial slope or femoral flexion-crucial aspects of 3D surgical planning. Therefore, more comprehensive knee phenotyping solutions are required to guide individualised TKA alignment strategies.

Level of Evidence

Level II.

Assessment of preoperative planning and intraoperative accuracy of the AIKNEE system for total knee arthroplasty

BACKGROUND

The aim of this retrospective study was to evaluate the effectiveness and accuracy of the AIKNEE system in preoperative planning and intraoperative alignment for total knee arthroplasty (TKA).

METHODS

A total of 64 patients were planned preoperatively by the AIKNEE system, including the measurement of mechanical femorotibial angle (mFTA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) using three-dimensional reconstructed images. Intraoperatively, the actual prosthesis size and alignment were compared to the planned parameters. Postoperative outcomes, including pain levels, range of motion (ROM), and Knee Scoring System (KSS) scores, were assessed after surgery. Statistical analyses were performed to evaluate the correlation between alignment deviations and postoperative function.

RESULTS

The AIKNEE system accurately predicted the prosthesis size in thirty-one of femoral cases (48%) and forty-seven of tibial cases (73%). Deviations of mFTA, LDFA, and MPTA from the target value were within 3° in 88%, 92%, and 95% of cases, respectively. A significant improvement was observed in postoperative pain, ROM, and KSS scores (p < 0.001). Correlation analysis revealed that greater deviations in mFTA and LDFA were associated with increased pain (p = 0.004, 0.047) and lower KSS scores (p = 0.027).

CONCLUSION

The AIKNEE system demonstrated promising results in predicting prosthesis size and achieved alignment within the desired range in a majority of cases. Postoperative outcomes, including pain levels and functional improvement, were favorable.

Smith machine squats pose high risk to ACL graft integrity after the ACL reconstruction and conventional squats are a safer alternative

PURPOSE

The purpose of this study was to evaluate the impact of squats after the anterior cruciate ligament (ACL) reconstruction on the ACL graft, considering new data on biomechanics, posterior tibial slope (PTS) and anterolateral ligament (ALL).

METHODS

Utilising finite element analysis on the new 14-component knee joint model, we have evaluated stresses on the knee elements separately for the knee with a native double-bundle ACL and with a single-bundle ACL graft for the 5° and 14° PTS variants during both conventional and Smith machine horizontal squats.

RESULTS

Replacing a native ACL with a single-bundle graft causes an overstrain on the graft compared to the intact ACL under all conditions. Stresses on the ACL, ACL graft and ALL are much higher during the Smith machine squats compared to the conventional ones. The stress on the menisci is 3.6-4.9 times higher with conventional squats. PTS at the squats' lowest point minimally affects ACL stress but impacts menisci.

CONCLUSIONS

The single-bundle ACL reconstruction (ACLR) does not reproduce the biomechanics of the native ACL and increases stresses in most knee joint elements, according to the current study. Conventional squats are relatively safe for the ACL graft at their lowest point. Passing the half-squat position is the most dangerous point. Smith machine horizontal squats produce stress on the ACL graft several times higher than its estimated breaking load and dangerous stress levels on the ALL. During the rehabilitation following ACLR, it is advisable to prioritise the conventional squats over Smith machine squats until ligamentisation is complete.

LEVEL OF EVIDENCE

Level III.

Bicondylar tibial plateau fracture osteosynthesis with double-plate fixation: Similar complication rates and clinical results but improved radiographic outcomes with dual compared to single approach

INTRODUCTION

Associating posteromedial and anterolateral approaches should improve fracture line visualization and optimize bicondylar tibial plateau fracture reduction compared to a single midline approach. The present study aimed to compare postoperative complications rates and functional and radiographic results after double-plate fixation via either a single or a dual approach. The study hypothesis was that double-plate fixation using a dual approach provides equivalent complications rates with improved radiographic results compared to a single approach.

MATERIAL AND METHODS

A retrospective 2-center study compared bicondylar tibial plateau fractures treated by double-plate fixation on a single versus a dual approach between January 2016 and December 2020. Comparison focused on major complications requiring surgical revision, radiographic measurements of medial proximal tibial angle (MPTA) and posterior proximal tibial angle (PPTA); change from their respective baseline values of 87° and 83° (deltaMPTA and deltaPPTA), and functional results on KOOS, SF12 and EQ5D-3L self-reported questionnaires.

RESULTS

Major complications occurred in 2 of the 20 single approach group patients (10%) [1 surgical site infection (SSI) (5%), and 1 skin complication (5%)], and in 3 of the 39 dual approach group patients (7.69%) (p=0.763), at an average 29 months' follow-up. In the sagittal plane, deltaPPTA was significantly lower with dual than single approach (respectively, 4.67° versus 7.43°; p=0.0104). There were no significant intergroup differences in deltaMPTA or functional results at last follow-up.

CONCLUSION

The present study suggests an absence of significant difference in major complications, between single and dual approach for double-plate osteosynthesis of bicondylar tibial plateau fractures. Using a dual approach enabled improved anatomic restoration in the sagittal plane, without significant differences observed in the frontal plane or functional scores at an average 29months' follow-up.

LEVEL OF EVIDENCE

III; case-control study.

The posterior tibial slope affects the measurement reliability regarding the radiographic parameter of the knee

BACKGROUND

Posterior tibial slope (PTS) exhibits considerable variability among individuals and is anticipated to influence the accuracy of radiographic measurements related to the knee. Despite this potential impact, there is a lack of prior research investigating how PTS affects the accuracy of these measurements. Therefore, this study aimed to investigate the effect of PTS on the measurement reliability regarding the radiographic parameter of the knee.

METHODS

The medical records of patients who took full-length anteroposterior radiographs of the lower limb between January 2020 and June 2022 were evaluated retrospectively. Radiographic parameters related to the knee joint characteristics such as osteoarthritis grade, hip-knee-ankle angle, weight-bearing line ratio, medial proximal tibial angle (MPTA), lateral distal femoral angle, joint-line convergence angle (JLCA), and PTS were measured. Subjects were classified into 3 groups according to PTS (group A, PTS < 4°; group B, PTS ≥ 4° and < 8°; group C, PTS ≥ 8°), and the measurement reliability for the radiographic variables was compared between groups. The intra- and inter-observer agreements were assessed using the kappa coefficients, intra-class correlation coefficients (ICC), and Bland-Altman plots.

RESULTS

A total of 175 limbs (86 patients) were included in this study. As the intra- and inter-observer reliability for PTS ranged over 0.9, grouping was performed based on the average of the measured PTSs. The inter-observer reliability of the MPTA and JLCA decreased as the PTS increased (ICCs for MPTA in Groups A, B, and C: 0.889, 0.796, and 0.790, respectively; ICCs for JLCA in Groups A, B and C: 0.916, 0.859, and 0.843, respectively), whereas there were no remarkable differences in other variables. Similar trends were observed in the comparisons of intra-observer reliability and Bland-Altman plots also showed consistent results.

CONCLUSION

The larger the PTS, the lower the measurement reliability regarding the radiographic parameters of the knee that includes the joint line, such as MPTA and JLCA. Given the occasional challenge in accurately identifying the knee joint line in patients with a relatively large PTS, careful measurement of radiographic parameters is crucial and utilizing repetitive measurements for verification may contribute to minimizing measurement errors.

Large multiplanar changes to native alignment have no apparent impact on clinical outcomes following total knee arthroplasty

PURPOSE

This study sought to examine if achieved postoperative alignment when compared to the native anatomy would lead to a difference in Patient Reported Outcome Measures (PROMs), and whether the achieved alignment could be broadly categorised by an accepted alignment strategy.

METHODS

A retrospective cohort study of prospectively collected data on patients undergoing single primary or bilateral simultaneous total knee arthroplasty (TKA) was carried out. CT scans were used to determine the mean change ("delta values") between the pre and postoperative; hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle and femoral implant rotation. Femoral implant flexion and tibial implant slope were measured postoperatively. The primary outcome was the relationship of the variables to the change in KOOS pain subscale after one year. The secondary outcome was the number of knees which could be categorised postoperatively to an alignment strategy, and the mean PROMs in each cohort.

RESULTS

A total of 296 knees in 261 patients were available for analysis. With regards to the primary outcome, the delta values for each variable did not demonstrate any association with the change in knee injury and osteoarthritis outcome score (KOOS) pain score. Approximately 46% of knees could not be categorised to an alignment strategy based on postoperatively measured alignment, with no significant difference between each cohort with regards to the change in KOOS Pain score.

CONCLUSION

Achieved alignment does not consistently match accepted alignment strategies, and appears to confer no benefit to clinical outcomes when the native anatomy is most closely approximated, nor results in poorer outcomes in outliers. This study highlights the importance of routine three dimensional pre and postoperative imaging in clinical practice and for the valid analysis of outcomes in studies on alignment.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Anterior metaphyseal angle; much less individual variation in determining the posterior slope of the tibia

BACKGROUND

The question of how to specify the posterior tilt of the tibia during arthroplasty operations remains unclear. The most current opinion is that a design whereby incisions are made in parallel with the individual pre-arthritic posterior tilt will yield better post-operational results. However, the wide range of inter-individual variations of posterior tilt of the tibia and the difficult task of identifying the shaft axis of the tibia through standard lateral radiographs are the main obstacles to this particular method. Therefore, there is a need for another reference line that can be measured with plain radiography and yields less inter-individual variation. The hypothesis of this study was that the angle formed between the anterior metaphyseal line of the proximal tibia and the tibial plateau would prove to be less variable across individuals.

METHODS

Long-shot radiographs of non-rotating lateral tibias of 85 patients aged between 18 and 38 years were analysed. The angle forming between the anterior metaphyseal line of the proximal tibia and the slope of the tibial plateau, and the posterior slope angle was measured by 2 separate observers using the classical method.

RESULTS

From the measurements of the posterior slope angle taken with the classical method, 38% (33/85) of the patients were within the ±2-degree range of the mean, and the anterior metaphyseal angle was within ±2 degrees of the mean in 75% (64/85) of the total patients. 44.23% variation (CoV) in posterior slop degrees, 2.73% (CoV) variation in the anterior metaphyseal angle measured by the same researchers. The difference between the percentages of variation was also found to be statistically significant. (z = 15.36, p = 0.000).

CONCLUSION

The anterior metaphyseal angle can be utilized to predict the individual posterior slope. Nevertheless, further large-scale, multicentre studies are needed to establish a mean value for the population.

No significant post-operative limb length difference following medial opening wedge high tibial osteotomy in a multi-ethnic Southeast Asian population

PURPOSE

This study aims to assess the significance of post-operative change in limb length in medial opening wedge high tibial osteotomy (MOWHTO), and evaluate the correlation between correction angles and changes in limb length. We hypothesize that opening wedge height and correction angles directly correlate to changes in limb length.

METHODS

The medical records and radiographs of 91 MOWHTO patients were retrospectively evaluated for relevant radiographical parameters both pre- and post-operatively. The exclusion criteria are: (i) concurrent distal femur osteotomy in the same setting, (ii) other previous unilateral lower limb surgeries prior to MOWHTO and (iii) failure to follow-up with post-operative radiographs. A linear regression model was performed and a line of best fit, Pearson's correlation coefficient (r) and coefficient of determination (R2) were computed. Chi-squared test was also performed, and results with P < 0.05 were considered statistically significant.

RESULTS

There is a statistically significant increase in post-MOWHTO limb length (Absolute Δ = 4.3 ± 2.86 mm, % Δ = 0.652% ± 0.434%, p < 0.001). There was no significant difference in the limb length change between patients with larger (> 8 mm) and smaller (< 8 mm) opening widths. There was a weakly positive correlation between limb length change versus actual (R2 = 0.140, 95%CI [-0.068, 0.336]) and planned correction angles (R2 = 0.196, 95%CI [-0.012, 0.387]).

CONCLUSION

In conclusion, post-MOWHTO change in limb length is statistically significant, but the clinical significance is minimal. Further studies are required to assess other factors. Development of a reliable mathematical model that predicts post-MOWHTO limb length change would be useful in predicting the anatomical outcomes.

LEVEL OF EVIDENCE

Level III. Retrospective Cohort Study.

CT-based analysis of posterior tibial slope in a Turkish population sample: A retrospective observational study

Posterior tibial slope (PTS) is important for the success of high tibial osteotomy and unicondylar knee arthroplasty applications, as it provides anterior cruciate ligament function. In the literature, different studies have been carried out with various imaging methods to measure PTS in populations of different ethnic origins. In this study, it was aimed to detect PTS in the medial (MPTS) and lateral (LPTS) tibial condyles with computed tomography in a Turkish population sample and to compare the results between age groups (<65, ≥ 65), genders, sides, and literature data. In our sample, 39 left and 33 right knee images of 37 men and 35 women with a mean age of 52.01 ± 21.27 were evaluated. The tibial proximal anatomical axis was determined by the midpoint method. The MPTS and LPTS was evaluated by two different observers according to this axis. Thereby the global PTS (GPTS) was calculated as an arithmetic mean of MPTS and LPTS values. Measurements were repeated 2 weeks after the first measurement and values were analyzed. A significant difference was found between the mean of MPTS, LPTS, and GPTS in the whole population (P = .002), in men (P = .02) and in women (P = .02). On the other hand, there was no significant difference compared according to age, gender, and side by mean of same parameters. In comparison of the results of our Turkish population sample with other studies in the literature, MPTS and LPTS were similar to Chinese (P = .22, P = .07) and Japanese (P = .96, P = .67) populations, while different to White Asian (P < .001, P < .001) and Korean (P < .001, P < .001) populations. The midpoint method is a safe measurement method in computed tomography-based studies for the evaluation of PTS. Implant designs produces for different populations may not be suitable for the Turkish population. More comprehensive and detailed studies are needed to represent the Turkish population.

Steep posterior slope of the medial tibial plateau and anterior cruciate ligament degeneration contribute to medial meniscus posterior root tears in young patients

PURPOSE

Medial meniscus posterior root tears (MMPRTs) occur most frequently in middle-aged and older adults. However, this serious condition can also occur in younger patients. The purpose of this study was to compare anterior cruciate ligament (ACL) degeneration and sagittal medial tibial slope in young adults with and without MMPRT.

METHODS

Eighteen healthy volunteers, 18 young patients (20-49 years of age), and 30 middle-aged and older patients (50-70 years of age) with MMPRT repair were included in the study. Sex, body mass index (BMI), femorotibial angle, ACL degeneration, and medial tibial slope angle were compared among the groups. ACL degeneration and medial tibial slope angle were assessed using magnetic resonance imaging.

RESULTS

In the healthy volunteer group, the young patient group, and the older patient group, the medial tibial slopes were 3.5° ± 1.4°, 6.1° ± 2.7°, and 7.2° ± 1.9°, respectively, and the ACL degeneration rates were 5.6%, 38.9%, and 43.3%, respectively. Young patients with MMPRT had significantly steeper medial tibial slopes and ACL degeneration compared to those of the healthy volunteers (P < 0.05). The parameters of young patients were similar to those of older patients with MMPRT. In the multivariate logistic regression analysis, BMI, medial tibial slope, and ACL degeneration were significantly associated with MMPRT in young patients.

CONCLUSION

BMI, steep medial tibial slope, and ACL degeneration contribute to MMPRT development in younger patients.

LEVEL OF EVIDENCE

Level III.

Relative Sagittal Alignment of the Medial and Lateral Articular Surfaces of the Tibial Plateau Using Radiographic Parameters: A Radiographic Cadaveric Study

OBJECTIVES

To characterize anatomic slope (sagittal alignment) of medial and lateral articular surfaces of the tibial plateau using x-ray and computed tomography (CT).

METHODS

Fluoroscopy was used to acquire "perfect" anteroposterior (AP) images of 8 cadaveric knees by tilting a C-arm through a 30-degree cranial/caudal arc in 0.5-degree increments. Five surgeons independently selected perfect AP images that most accurately profiled medial and lateral articular surfaces. Corresponding angles were used to define tangent subchondral structures on sagittal CT that were considered as dominant bony landmarks in a protocol to determine tibial slope on sagittal CT in 46 additional cadaveric knees.

RESULTS

Mean perfect C-arm AP angles were 4.2 degrees ± 2.6 degrees posterior for the medial plateau and 5.0 degrees ± 3.8 degrees posterior for the lateral plateau. It was noted that images acquired within a range of angles (medial range, 1.8 degrees ± 0.7 degrees; lateral range, 3.9 degrees ± 3.8 degrees) rather than a single angle adequately profiled each compartment. Using the CT protocol, mean medial slope (5.2 degrees ± 2.3 degrees posterior; range, 0.9-11.5 degrees) was less than lateral slope (7.5 degrees ± 3.0 degrees posterior; range 0.6-12.5 degrees; P < 0.001) in 54 knees. The difference between medial and lateral slopes in any individual specimen ranged from 3.1 degree more medially to 6.8 degrees more laterally. No differences were noted between right and left knees in paired specimens.

CONCLUSIONS

On average, tibial slope in the lateral plateau is slightly greater than that in the medial plateau, and variation exists between compartments across patients. Because tibial slope is similar between contralateral limbs, evaluating slope on the uninjured side can provide a template for sagittal plane reduction of tibial plateau fractures.

Cutting-Edge Approaches in Arthroplasty: Before, during and after Surgery

Personalised medicine was introduced in arthroplasty a long time ago with the aim of respecting each individual person for their unique personal characteristics in order to further improve outcomes [...].

Comparison of the Tibial Posterior Slope Angle Between the Tibial Mechanical Axis and Various Diaphyseal Tibial Axes After Total Knee Arthroplasty

Background

The posterior tibial slope angle (PTS) is crucial for sagittal alignment after total knee arthroplasty (TKA). This study aimed to determine which PTS based on the lateral view of standard knee radiographs (LSKRs; 36 × 43 cm) reflects the PTS based on a full-length lateral tibial radiograph (FLTR).

Methods

A total of 290 patients (355 knees) who underwent primary TKA were retrospectively recruited. Cross-sectional views from the 3-dimensional digital model of the tibial prosthesis and bone complex in the sagittal plane were used as FLTRs and LSKRs. Considering the region 21.5 cm proximal to the site of FLTR as the spot for LSKR to determine the 5 tibial diaphyseal axes, the axis that simulates the PTS as determined by the tibial mechanical axis between the center of the tibial component and the ankle plafond in LSKR was determined and compared.

Results

PTS (α₅) defined by the line connecting the midpoints of tibial width between the region 10-cm distal to the knee joint and the distal end of the tibia based on LSKR revealed the least mean difference (0.13° ± 1.00°) and the strongest correlation (P < .001, r = 0.948) with PTS based on FLTR (α₀). The number of knees in α₅, indicating a difference of <2° from α₀, was 333 of 355 (93.8%). The equivalence test results indicated that α₀ and α₅ were statistically equivalent within a difference of 2° (P < .001).

Conclusions

PTS (α₅) can be used as a clinically reliable substitution of the true PTS on an FLTR for evaluating sagittal alignment after TKA.

Medial proximal tibial angle at the posterior tibial plateau represents the pre-arthritic constitutional medial proximal tibial angle in anterior cruciate ligament-intact, advanced osteoarthritis of the knee

PURPOSE

In kinematically aligned total knee arthroplasty (TKA), it is necessary to infer the pre-arthritic constitutional medial proximal tibial angle (MPTA) in advanced osteoarthritis (OA) of the knee with bone loss. The aim of this study was to investigate whether MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA in anterior cruciate ligament (ACL)-intact, advanced OA knees. It was hypothesized that MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA of ACL-intact, advanced knee OA.

METHODS

One hundred varus, anterior cruciate ligament (ACL)-intact, advanced OA knees were analysed. The hip-knee-ankle (HKA) angle and MPTA were assessed on computed radiography (CR) and MPTAs at the anterior, middle, and posterior part of the tibial plateau were assessed on computed tomography (CT) images. The association between these parameters was also analysed.

RESULTS

CR images showed an HKA angle of 172.4 ± 4.1° and MPTA of 84.3 ± 2.5°. CT images showed different MPTAs in the three regions, ranging from 83.9 ± 2.4° to 85.9 ± 2.8°. The middle MPTA was the lowest at 83.9 ± 2.4°. HKA angle correlated with the middle MPTA (r = 0.3355, 95% confidence interval [CI] 0.1489-0.4991, p = 0.0006) and ΔMPTA (Middle-Posterior) (r = 0.5128, 95% CI 0.3518-0.6443, p < 0.0001).

CONCLUSION

The MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA in ACL-intact, advanced OA knees.

LEVEL OF EVIDENCE

III, retrospective cohort study.

The risk of tibial eminence avulsion fracture with bi-unicondylar knee arthroplasty : a finite element analysis

AIMS

The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

METHODS

Two experimentally validated finite element models of tibia were implanted with UKA-M, Bi-UKA, and BCR-TKA. Intraoperative loads were applied through the condyles, anterior cruciate ligament (ACL), medial collateral ligament (MCL), and lateral collateral ligament (LCL), and the risk of fracture (ROF) was evaluated in the spine as the ratio of the 95^th percentile maximum principal elastic strains over the tensile yield strain of proximal tibial bone.

RESULTS

Peak tensile strains occurred on the anterior portion of the medial sagittal cut in all simulations. Lateral translation of the medial implant in Bi-UKA had the largest increase in ROF of any of the implant positions (43%). Overstuffing the joint by 2 mm had a much larger effect, resulting in a six-fold increase in ROF. Bi-UKA had ~10% increased ROF compared to UKA-M for both the male and female models, although the smaller, less dense female model had a 1.4 times greater ROF compared to the male model. Removal of anterior bone akin to BCR-TKA doubled ROF compared to Bi-UKA.

CONCLUSION

Tibial eminence avulsion fracture has a similar risk associated with Bi-UKA to UKA-M. The risk is higher for smaller and less dense tibiae. To minimize risk, it is most important to avoid overstuffing the joint, followed by correctly positioning the medial implant, taking care not to narrow the bone island anteriorly.Cite this article: Bone Joint Res 2022;11(8):575-584.

Osseous Morphological Differences in Knee Osteoarthritis

BACKGROUND

Improved understanding of the morphological characteristics of knees with osteoarthritis (OA) and various deformities can enable personalized implant positioning and balancing in total knee arthroplasty in an effort to continue improving clinical outcomes and optimizing procedural value. Therefore, the purpose of this study was to outline morphological differences in the medial and lateral distal femur and proximal tibia associated with varus and valgus deformities in knee OA.

METHODS

A large computed tomography (CT) database was used to identify 1,158 knees, which were divided into normal and osteoarthritic groups; the latter was further divided on the basis of deformity into neutral, varus, and valgus subgroups. Morphological measurements included the non-weight-bearing hip-knee-ankle angle (nwHKA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), rotation of the posterior condylar axis (PCA) relative to the surgical transepicondylar axis (sTEA), ratio of medial to lateral posterior condylar offset, ratio of medial to lateral condylar radius, medial posterior slope (MPS), lateral posterior slope (LPS), medial coronal slope (MCS), and lateral coronal slope (LCS).

RESULTS

Compared with the normal group, the OA group was in overall varus (nwHKA, -2.2° ± 5.0° compared with -0.2° ± 2.4°) and had a significantly smaller MPS (8.4° ± 4.0° compared with 9.2° ± 4.0°), larger LPS (9.2° ± 3.6° compared with 7.2° ± 3.3°), and smaller MCS (82.1° ± 4.3° compared with 83.9° ± 3.3°). Differences among the OA subgroups were also observed for the MCS and LCS. Compared with the normal group, the sTEA of the OA group was less externally rotated relative to the PCA (0.3° ± 1.5° compared with 1.2° ± 1.9°), and both the condylar offset ratio (1.01 ± 0.06 compared with 1.04 ± 0.07) and the condylar radius ratio (0.98 ± 0.07 compared with 1.03 ± 0.07) were smaller. Only the condylar radius ratio showed differences among the OA subgroups, with valgus deformity associated with a larger ratio.

CONCLUSIONS

An analysis of CT scans of 965 healthy and 193 osteoarthritic knees revealed significant differences in PCA, condylar offset, and condylar radius as well as tibial slope in both the sagittal and coronal planes.

CLINICAL RELEVANCE

There is a strong need to evolve toward a more personalized treatment for osteoarthritic knees that utilizes implants and technology to help tailor total knee arthroplasty on the basis of the patient's morphologic characteristics.

Dynamic Mediolateral Patellar Translation Is a Sex- and Size-Independent Parameter of Adult Proximal Patellar Tracking Using Dynamic 3 Tesla Magnetic Resonance Imaging

PURPOSE

To provide normal values for physiological patellofemoral tracking in a representative group of healthy individuals, as well as sex differences, using real-time 3T-magnetic resonance imaging (MRI) and to test for the reliability of the presented technique.

METHODS

One hundred knees of healthy individuals with no history of patellofemoral symptoms were scanned with dynamic MRI sequences, during repetitive cycles of flexion (40°) and full extension. Within a 30-seconds time-frame, three simultaneous, transverse slices were acquired. Dynamic mediolateral patellar translation (dMPT) and dynamic patellar tilt (dPT) were measured on two occasions by two independent examiners. Common radiological parameters were measured using static MRI, and correlations were calculated.

RESULTS

100 knees (53 right, 47 left; age: 26.7 ± 4.4 years; BMI: 22.5 ± 3.1) of 57 individuals (27 females, 30 males) were included. Mean height was 170.1 ± 7.7 cm in women and 181.8 ± 6.4 cm in men. Average patella diameter was 37.9 ± 2.7 (95% CI 37.1-38.7) mm in women and 42.4 ± 3.2 (95% CI 41.5-43.3) mm in men. In females, the patellar diameters and intercondylar distances were significantly smaller than in males (P < .001). Radiological parameters for patellar maltracking were within the normal range. During the range of motion, mean dMPT was 1.7 ± 2.4 (95% CI .9-2.5) mm in females and 1.8 ± 2.7 (95% CI 1.1-2.6) mm in males (P = .766). Mean dPT was 1.3 ± 2.9° (95% CI .4-2.1°) in females and -0.2 ± 3.8° (95% CI -1.2-.9°) in males (P = .036). Neither dMPT nor dPT was correlated with height, BMI, or patellar diameter. Intercondylar distance correlated weakly with dPT (r = -.241; P = .041). Intra- and interrater reliability were excellent for dMPT and dPT.

CONCLUSION

Dynamic mediolateral patellar translation is a size- and sex-independent parameter for proximal patellar tracking. In healthy individuals without patellofemoral abnormalities normal dMPT proximal to the trochlea groove was 1.7 ± 2.5 (1.2-2.2) mm, independent of size or sex. Normal dPT showed a dependency on sex and was 1.3 ± 2.9 (.4-2.1)° in women and -0.2 ± 3.8 (-1.2-0.9)° in men.

LEVEL OF EVIDENCE

Level II, diagnostic study.

The Role of Stability and Alignment in Improving Patient Outcomes After Total Knee Arthroplasty

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Total knee arthroplasty (TKA) is an effective treatment option for many patients, but a small group of patients are dissatisfied following TKA.

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Alignment, in combination with balance, stability, and knee kinematics, is an important modifiable surgical factor that can affect patient outcomes.

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Driven by the subset of dissatisfied patients after TKA, new techniques have evolved in the search for a more anatomic reconstruction of individual knee morphology and a more accurate approximation of the individual lower-extremity alignment.

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There is a need to optimize 3 aspects of TKA to improve patient outcomes-mechanical tooling processes, implants that resurface the epiphysis, and techniques that respect the variable anatomy of patients.

High inter- and intraindividual differences in medial and lateral posterior tibial slope are not reproduced accurately by conventional TKA alignment techniques

PURPOSE

The purpose of this study was to describe the medial and lateral posterior tibial slope (MPTS and LPTS) on 3D-CT in a Caucasian population without osteoarthritis. It was hypothesised that standard TKA alignment techniques would not reproduce the anatomy in a high percentage of native knees.

METHODS

CT scans of 301 knees [male:female = 192:109; mean age 30.1 ([Formula: see text] 6.1)] were analysed retrospectively. Tibial slope was measured medially and laterally in relation to the mechanical axis of the tibia. The proportion of MPTS and LPTS was calculated, corresponding to the "standard PTS" of 3°-7°. The proportion of knees accurately reproduced with the recommended PTS of 0°-3° for PS and 5°-7° for CR TKA were evaluated.

RESULTS

Interindividual mean values of MPTS and LPTS did not differ significantly (mean (range); MPTS: 7.2° ( - 1.0°-19.0°) vs. LPTS: 7.2° ( - 2.4°-17.8°), n.s.). The mean absolute intraindividual difference was 2.9° (0.0°-10.8°). In 40.5% the intraindividual difference between MPTS and LPTS was > 3°. When the standard slope of 3°-7° medial and lateral was considered, only 15% of the knees were covered. The tibial cut for a PS TKA or a CR TKA changes the combined PTS (MPTS + LPTS) in 99.3% and 95.3% of cases, respectively.

CONCLUSION

A high interindividual range of MPTS and LPTS as well as considerable intraindividual differences were shown. When implementing the recommended slope values for PS and CR prostheses, changes in native slope must be accepted. Further research is needed to evaluate the impact of altering a patient's native slope on the clinical outcome.

LEVEL OF EVIDENCE

IV.

No difference in patient-reported satisfaction after 12 months between customised individually made and off-the-shelf total knee arthroplasty

PURPOSE

A subset of patients is usually not satisfied after a total knee arthroplasty (TKA). Customised individually made (CIM) TKA are deemed to overcome drawbacks of classical off-the-shelf (OTS) TKA, but evidence is still sparse. The aim of this study was to compare satisfaction of patients with CIM and OTS TKA.

METHODS

This prospective cohort study compared clinical and patient-reported outcome measures (PROM) between patients with CIM and OTS TKA. The primary outcome was patient satisfaction after 12 months. Secondary outcomes were the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), the Forgotten Joint Score (FJS-12) and the EQ-5D-3L after 4 and 12 months.

RESULTS

Data were analysed from 74 CIM TKA and 169 OTS TKA between January 2017 and September 2020. Patients with CIM TKA were slightly younger, more often male, had a lower body mass index, a lower KSS and partially higher preoperative PROMs. Patient satisfaction after 12 months was high and comparable (CIM 87%, OTS 89%). All PROMs improved for both groups (p < 0.001) and did not differ after 12 months (p > 0.063). The majority of patients improved above the minimal important difference (range 65 to 89%) and reported a clear overall improvement (CIM 86%, OTS 87%). The postoperative KSS, notably regarding knee stability, was higher for CIM TKA (p < 0.001).

CONCLUSION

No difference was found in patient satisfaction between CIM and OTS TKA after 12 months. In both groups, patient satisfaction was high and PROMs improved considerably.

LEVEL OF EVIDENCE

II, prospective cohort study.

Joint line is restored in robotic-arm-assisted total knee arthroplasty performed with a tibia-based functional alignment

INTRODUCTION

Functional alignment (FA) in total knee arthroplasty (TKA) has been introduced to restore the native joint line obliquity, respect the joint line height and minimize the need of soft tissue releases. The purpose of this study was to assess the intraoperative joint line alignment and compare it with the preoperative epiphyseal orientation of the femur and tibia in patients undergoing robotic-arm-assisted (RA)-TKA using FA.

MATERIALS AND METHODS

This retrospective study included a consecutive series of patients undergoing RA-TKA between February 2019 and February 2021. The joint line orientation of the femur and tibia in the three-dimensions was calculated and classified on preoperative CT-scans and compared with the intraoperative implant alignment. The tibial cut was performed according to the tibial preoperative anatomy. The femoral cuts were fine-tuned based on tensioned soft tissues, aiming for balanced medial and lateral gaps in flexion and extension.

RESULTS

A total of 115 RA-TKAs were assessed. On average, the tibial component was placed at 1.8° varus (SD 1.3), while the femur was placed at 0.8° valgus (SD 2.2) and 0.6° external rotation (SD 2.6) relative to the surgical transepicondylar axis. Moderate to strong, statistically significant relationships were described between preoperative tibial coronal alignment and tibial cut orientation (r = 0.7, p < 0.0001), preoperative femoral orientation in the coronal and axial planes and intraoperative femoral cuts alignment (r = 0.7, p < 0.0001 and r = 0.5, p < 0.0001, respectively). One case (0.9%) of slight tibial component varus subsidence was reported 45-days post-operatively, but implant revision was not necessary.

CONCLUSIONS

The proposed robotic-assisted functional technique for TKA alignment, with a restricted tibial component coronal alignment, based on the preoperative phenotype and femoral component positioning as dictated by the soft tissues, provided joint line respecting resections. Further studies are needed to assess long-term implant survivorship, patient satisfaction and alignment-related failures.

Specific case consideration for implanting TKA with the Kinematic Alignment technique

The Kinematic Alignment (KA) technique for total knee arthroplasty (TKA) is an alternative surgical technique aiming to resurface knee articular surfaces.The restricted KA (rKA) technique for TKA applies boundaries to the KA technique in order to avoid reproducing extreme constitutional limb/knee anatomies.The vast majority of TKA cases are straightforward and can be performed with KA in a standard (unrestricted) fashion.There are some specific situations where performing KA TKA may be more challenging (complex KA TKA cases) and surgical technique adaptations should be included.To secure good clinical outcomes, complex KA TKA cases must be preoperatively recognized, and planned accordingly.The proposed classification system describes six specific issues that must be considered when aiming for a KA TKA implantation.Specific recommendations for each situation type should improve the reliability of the prosthetic implantation to the benefit of the patient.The proposed classification system could contribute to the adoption of a common language within our orthopaedic community that would ease inter-surgeon communication and could benefit the teaching of the KA technique. This proposed classification system is not exhaustive and will certainly be improved over time. Cite this article: EFORT Open Rev 2021;6:881-891. DOI: 10.1302/2058-5241.6.210042.

Tibial Sagittal Slope in Anterior Cruciate Ligament Injury and Treatment

Although anterior cruciate ligament reconstruction (ACLR) is a generally successful procedure, failure is still relatively common. An increased posterior tibial slope (PTS) has been shown to increase the anterior position of the tibia relative to the femur at rest and under load in biomechanical studies. Increased PTS has also been shown to increase forces on the native and reconstructed ACL. Clinical studies have demonstrated elevated PTS in patients with failed ACLR and multiple failed ACLR, compared with control subjects. Anterior closing-wedge osteotomies have been shown to decrease PTS and may be indicated in patients who have failed ACLR with a PTS of ≥12°. Available clinical data suggest that the procedure is safe and effective, although evidence is limited to case series. This article presents the relevant biomechanics, clinical observational data on the effects of increased PTS, and an algorithm for evaluating and treating patients with a steep PTS.

Restoring the Patient's Pre-Arthritic Posterior Slope Is the Correct Target for Maximizing Internal Tibial Rotation When Implanting a PCL Retaining TKA with Calipered Kinematic Alignment

INTRODUCTION

The calipered kinematically-aligned (KA) total knee arthroplasty (TKA) strives to restore the patient's individual pre-arthritic (i.e., native) posterior tibial slope when retaining the posterior cruciate ligament (PCL). Deviations from the patient's individual pre-arthritic posterior slope tighten and slacken the PCL in flexion that drives tibial rotation, and such a change might compromise passive internal tibial rotation and coupled patellofemoral kinematics.

METHODS

Twenty-one patients were treated with a calipered KA TKA and a PCL retaining implant with a medial ball-in-socket and a lateral flat articular insert conformity that mimics the native (i.e., healthy) knee. The slope of the tibial resection was set parallel to the medial joint line by adjusting the plane of an angel wing inserted in the tibial guide. Three trial inserts that matched and deviated 2°> and 2°< from the patient's pre-arthritic slope were 3D printed with goniometric markings. The goniometer measured the orientation of the tibia (i.e., trial insert) relative to the femoral component.

RESULTS

There was no difference between the radiographic preoperative and postoperative tibial slope (0.7 ± 3.2°, NS). From extension to 90° flexion, the mean passive internal tibial rotation with the pre-arthritic slope insert of 19° was greater than the 15° for the 2°> slope (p < 0.000), and 15° for the 2°< slope (p < 0.000).

DISCUSSION

When performing a calipered KA TKA with PCL retention, the correct target for setting the tibial component is the patient's individual pre-arthritic slope within a tolerance of ±2°, as this target resulted in a 15-19° range of internal tibial rotation that is comparable to the 15-18° range reported for the native knee from extension to 90° flexion.

Contemporary knee arthroplasty: one fits all or time for diversity?

INTRODUCTION

Total knee arthroplasty (TKA) has historically been the preferred solution for any type of knee osteoarthritis, independently of the number of compartments involved. In these days of patient-specific medicine, mono-compartmental disease could also be approached with a more individualized treatment, such as partial knee arthroplasty (PKA). Off-the-shelf (OTS) implants are often the compromise of averages and means of a limited series of anatomical parameters retrieved from patients and the pressure of cost control by limited inventory. Personalized medicine requires respect and interest for the individual shape and alignment of each patient.

MATERIALS AND METHODS

A Pubmed and Google Scholar search were performed with the following terms: "patient-specific knee" and "arthroplasty" and "custom implant" and "total knee replacement" and "partial knee replacement" and "patellofemoral knee replacement" and "bicompartmental knee replacement". The full text of 90 articles was used to write this narrative review.

RESULTS

Unicondylar, patellofemoral and bicompartmental knee arthroplasty are successful treatment options, which can be considered over TKA for their bone and ligament sparing character and the superior functional outcome that can be obtained with resurfacing procedures. For TKA, where compromises dominate our choices, especially in patients with individual variations of their personal anatomy outside of the standard, a customized implant could be a preferable solution.

CONCLUSION

TKA might not be the only solution for every patient with knee osteoarthritis, if personalized medicine wants to be offered. Patient-specific mono-compartmental resurfacing solutions, such as partial knee arthroplasty, can be part of the treatment options proposed by the expert surgeon. Customized implants and personalized alignment options have the potential to further improve clinical outcome by identifying the individual morphotype and respecting the diversity of the surgical population.