Differences of knee anthropometry between Chinese and white men and women

Evaluation of the relationship between non-contact anterior cruciate ligament rupture and eminential morphometry: a cross-sectional and MRI based study

BACKGROUND

The literature does not clearly convey the relationship between eminential morphometry and non-contact anterior cruciate ligament (ACL) ruptures. This study attempts to reveal whether there is a relationship between non-contact ACL ruptures and eminential morphometry.

METHODS

Knee magnetic resonance images (MRIs) taken for the various indications between January 2022 and June 2023 were retrospectively scanned. The patients were categorized into 2 groups: those with an ACL rupture and those with an intact ACL. For each patient, eminential angle 1, eminential angle 2, medial eminential height, lateral eminential height, total eminential height, eminential width, and the ratio of tibial plateau width and eminential width to the tibial plateau width were measured by 2 different orthopedists. Patients whose MRIs were used for measurement were evaluated and grouped according to their age, sex, and injury side.

RESULTS

In total, 400 MRIs of 400 patients were included in the study. While 200 patients had an ACL rupture, 200 had an intact ACL. The total eminential height in the ACL rupture group was measured at 16.1 ± 2.6 mm and 15.5 ± 2.7 mm (p = 0.035) in the ACL intact group. Eminental width in the ACL rupture group was measured at 12.1 ± 1.9 mm and 13.0 ± 2.0 mm in the ACL intact group (p = 0.0001). The tibial plateau width was 75.4 ± 15.7 mm in the ACL rupture group and 73.6 ± 5.8 mm in the ACL intact group (p = 0.002). According to the logistic regression analysis, the p-value for males was 0.0001, and for eminential width, the p-value was 0.0001.

CONCLUSIONS

A significant difference was found between the ACL rupture and the ACL intact groups regarding eminential height, eminential width, and tibial plateau width parameters. Being male and having a low eminential width were identified as independent risk factors for non-contact ACL.

TRIAL REGISTRATION

Not applicable.

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 (1).

Does the femoral component design modified in consideration of Asian anatomical characteristics fit better than the conventional design for Korean femora in reality?

INTRODUCTION

We aimed to investigate the anatomical and clinical advantages of an Asian-specific femoral component design with a high femoral aspect ratio, compared with the conventional femoral component design.

MATERIALS AND METHODS

A retrospective analysis of the operation and outpatient clinic records of 239 knees operated on using an anatomically modified femoral component design (MFCD, Group A) and 153 knees operated on using a conventional femoral component design (CFCD, Group B) in Korean patients was performed. Three subgroups were created based on the mediolateral size of the two different femoral component designs. The geometric accommodation of each femoral component was assessed using intraoperatively measured femoral posterior condylar resection and posterior condylar trimming amounts. Clinical outcomes were assessed using a range of motion (ROM) and patient-reported outcome measurements.

RESULTS

In the comparison between Groups A and B, the mean combined bilateral posterior condylar trimming (XPCT) was 2.91 [2SD: - 4.12-9.94] and 1.45 [2SD: - 5.89-8.80], and the median XPCT was 3 and 1.5. In the largest subgroup (subgroup 2), Groups A and B included 100 and 112 patients, all six posterior condylar resection and trimming parameters were significantly larger in Group A. Preoperative and postoperative ROM and Hospital for Special Surgery scores were similar between the two groups. Preoperative Western Ontario and McMaster Universities Arthritis Index (WOMAC) was higher in Group A. However, postoperative WOMAC was similar between the groups. Perioperative improvement in WOMAC index was significantly greater in Group B.

CONCLUSIONS

The Asian-specific femoral component design resulted in more resection and trimming of the femoral posterior condyle than the conventional design despite it was not associated with different clinical outcomes. Surgeons should be aware of unexpected excessive posterior condylar resection and formation of large flexion gap when using femoral component design with high femoral aspect ratio.

Anatomic Referencing of the Distal Femur in Total Knee Arthroplasty: The Impact of Orientation on Femoral Component Size

BACKGROUND

Anatomic referencing in total knee arthroplasty places the femoral component flush to the anterior cortex while maintaining posterior condylar offset (PCO). The intent of this study was to evaluate how component position influences the femoral component size.

METHODS

Digital surface models were created using 446 femora from an established computed tomography database. Virtual bone resections, component sizing, and component placement were performed assuming neutral (0°) flexion and neutral (3°) rotation relative to the posterior condyles. The appropriately sized femoral component, which had 2 mm of incremental size, was placed flush with the anterior cortex for optimal restoration of the PCO. Sizing and placement were repeated using 3 and 6° flexion and 0, 5, and 7° external rotation (ER).

RESULTS

At 0° flexion, decreasing ER from 3 to 0° resulted in an average decreased anterior-posterior height (APH) of 1.9 mm, corresponding to a component size decrease of 1 for 88% of patients. At 7° ER, component size increased by an average of 2.5 mm, corresponding to a size increase for 80% of patients. Flexing the femoral component to 3° with ER at 3° resulted in a decrease in APH of 2.2 mm (1 size decrease in 93% of patients). At 3° flexion and 3° ER, 86% had the same component size as at 0° flexion and 0° ER. Increasing ER at 3° flexion increased APH by 1.2 mm at 5° and 3.1 mm at 7° on average, relative to 3° ER. Increasing flexion from 3 to 6° extended this effect.

CONCLUSIONS

Flexion decreases the APH when the ER is held constant. The ER of the femoral component increases the APH across all tested flexion angles, causing an increase in the ideal femoral component size to maintain PCO. With anatomic referencing, alterations in femoral component positioning and subsequent changes in component size can be accounted for.

Periprosthetic tibial fracture as a complication of unicompartmental knee arthroplasty: Current insights

Periprosthetic fracture following knee arthroplasty is a rare but devastating complication associated with significant morbidity. With unicompartmental knee arthroplasty being performed far less frequently than total knee arthroplasty, periprosthetic fracture following unicompartmental knee arthroplasty presents a particular challenge to orthopaedic surgeons, due to clinical unfamiliarity and sparsity of literature. An up-to-date review of the epidemiology, risk factors, and management strategies for PPF after UKA is presented.

An Evaluation of Anatomic Referencing for Femoral Component Sizing Using Computed Tomography-Based Computer Modeling

One of the critical steps in total knee arthroplasty is femoral component positioning and sizing. Historically, there was wider variability between femoral component sizes, necessitating the concepts of anterior referencing (AR) and posterior referencing (PR). With the introduction of smaller increments between sizes, the concept of anatomic referencing has been introduced to replace AR and PR. The intent of this study was to validate the concept of anatomic referencing and show that with 2 mm increments in femoral sizes, the femoral component can be placed flush to the anterior cortex while maintaining posterior condylar offset (PCO). Digital surface models were created using 515 femurs from an established computed tomography database. Virtual bone resections, component sizing and placement were performed assuming neutral mechanical axis and a cartilage thickness of 2 mm. The appropriately sized femoral component, which had 2 mm incremental sizes, was placed flush with the anterior cortex with restoration of the PCO. The anterior-posterior distance from the posterior surface of the component to the medial and lateral surfaces of the posterior condylar cartilage were measured. The medial condyle was the limiting condyle in the majority of cases (73%). The average medial gap after appropriate femoral component matching was 0.6 mm (0.39-1.41 mm) across all sizes. The overall average condylar gap was 1.02 mm. The most common femoral component was a size 7 (57.2 mm) and the average femoral AP width was 55.9 mm. Anatomic referencing with an implant system that has 2-mm increments in femoral component sizing provides an alternative to AR and PR without compromise. Anatomic referencing allows for perfect alignment of the anterior flange of the femoral component to the anterior cortex of the femur while restoring the native PCO to within 1 mm. This avoids having to choose between AR or PR when in between femoral sizes.

Evaluating axial alignment and knee phenotypes in a young Indian population, using X-rays converted to three-dimensional bone models, and their relevance in total knee arthroplasty

PURPOSE

The standard principle of total knee arthroplasty (TKA) targeted by most orthopaedicians is the alignment of the lower limb in a neutral mechanical axis. However, for several patients the neutral mechanical alignment is not normal. Aligning these patients to a neutral mechanical axis may not result in desirable outcomes as it may feel unnatural. This study aimed to discover what percentage of the young healthy Indian population have a neutral hip-knee-ankle angle (HKA = 180°) and what percentage of this population have a deviation from the neutral HKA. We also studied the distribution of knee phenotypes in this non-arthritic population.

SUBJECTS AND METHODS

A total of 196 lower limbs were evaluated from 100 subjects, between the ages of 20 and 35 years, without any history of lower limb pathology, of which 50 were males and 50 were females. All volunteers were subjected to full-leg standing anteroposterior and lateral digital radiographs on which various alignment parameters were analysed. Three-dimensional bone models were generated using a validated software.

RESULTS

125 limbs (63.7%) from the total population lay in the range of 180 ± 3°; 7.14% (14/196) of the total limbs had an HKA angle of 180°; 29.5% (58/196) of the total population had a varus alignment, i.e., HKA angle of ≤176° and 6.6% (13/196) had knees in valgus alignment, i.e., HKA angle of ≥184°. Thirty-four percent (33/96) of limbs in men and 25% (25/100) of limbs in women had constitutional varus knees with an alignment of ≤176°; 5.2% (5) of limbs in men and 8% (8) of limbs in women had constitutional valgus knees with an alignment of ≥184°; 67/96 knees in males and 58 knees in females were in the range of 180 ± 3°.

CONCLUSIONS

A significant portion of the normal population had limbs that deviated from the neutral HKA. If these subjects were to need TKA in the future, it would not be desirable to restore their alignment to its neutral.

Are TomoFix Locking Plates Really Anatomical for Indian Population?

Purpose

The use of a TomoFix plate can be a challenge in Asian population who inherently have smaller tibial bones. This study aims to find out the normal proximal tibial morphometric measurements in Indian population and to compare the Medial Anterior Radius of Curvature (MAROC) of proximal tibia with the Proximal Part Radius of Curvature (PPROC) of the available TomoFix plates, to estimate conformity of the fit between them.

Methods

Retrospective Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) based proximal tibial measurements were performed on 824 knees, 664 females and 160 males (604 patients). The mean MAROC, mean MAROC in males and mean MAROC in females were compared to the PPROC of TomoFix plates.

Results

The radiological measurements revealed a mean AP length of 45.22 ± 3.79 mm, mean ML width of 69.04 ± 5.01 mm and mean MAROC of 21.88 ± 2.11 mm. The mean MAROC in males was 24.07 ± 2.1 mm, whereas in females it was 21.35 ± 1.75 mm. The mean MAROC, mean MAROC in males and mean MAROC in females when compared to the PPROC of Standard TomoFix plate (38 mm), Small TomoFix and Anatomical TomoFix plates (30 mm) showed a significant difference (p < 0.01), indicating that the radius of curvature of the plate does not match the radius of curvature of the anteromedial tibial plateau.

Conclusion

The TomoFix plates, including Small (Asian Version) and Anatomical plates, are relatively large for the Indian population. Our study may help the implant to designers develop a plate that will better suit the Indian population, improving results and reducing hardware-related complications of MOWHTO.

Anthropometry of Proximal Tibia in Patients Undergoing Total Knee Replacement at a Tertiary Care Hospital

Introduction Total knee arthroplasty is the standard of care treatment for advanced knee osteoarthritis. However, patients frequently continue to have pain and disability after surgery, with one of the most common reasons being a bone-implant mismatch. Notably, there is a significant difference reported in proximal tibia morphometry between Asian and Caucasian populations, and the currently available implants do not account for the anthropometric variations observed across ethnicities. We aimed to evaluate the proximal tibia anthropometry in a Pakistani population. Materials and methods A study was conducted at The Indus Hospital, Karachi Campus, from August 2019 to July 2020. All consecutive patients fulfilling the eligibility criteria and undergoing knee replacement surgery were included in the study. Baseline characteristics and anthropometry of proximal tibia were recorded on a pre-designed proforma. Statistical analysis was done using SPSS version 24. Results  A total of 30 patients were enrolled in this study, which included 17 females (56.7%) and 13 males (43.3%). The mean age was 61.6± 7.9 years and the BMI was 33±5.7 kg/m2. There was a significant difference found in the anteroposterior and mediolateral dimensions in both genders. A significant association was noted with body mass index (p-value 0.01) and occupation (p-value=0.02). Conclusion The results indicated that the anatomical profile of the proximal tibia in the Pakistani population is distinct, thus stressing the fact that it requires developing prostheses specifically tailored to this population's sizing requirements.

Arthroscopic debridement improves range of motion for heterotopic ossification after total knee replacement: a retrospective cohort study

The presence of heterotopic ossification (HO) after primary total knee replacement (TKR) is rare and associated with limited mobility and stiffness of the knee. This study aimed to identify if the arthroscopic debridement after TKR could decrease HO and improve the function and range of motion. Thirty HO patients after TKR were retrospectively separated into 2 cohorts. 15 patients of group A accepted the arthroscopic debridement, while 15 patients of group B only had non-operative treatment, mainly including oral nonsteroidal anti-inflammatory drugs (NSAIDs) and rehabilitative treatment. Visual analog scale (VAS) scores, knee society knee scores (KSS), range of motion (knee flexion and knee extension) were obtained before treatment and at 1 month, 3 months, and 6 months after treatment. Radiography of after-treatment was also evaluated to assess the changes in HO. There were 3 males and 27 females with a mean age of 67.4 ± 0.8 years in group A and 68.2 ± 1.3 in group B. The onset time of HO was 3-6 months. The maximum size of the ossification was < 2 cm in 23 knees, 2 cm < heterotopic bone < 5 cm in 6 knees and > 5 cm in 1 knee. The size of HO decreased gradually in all knees by X-ray film at the last follow-up. There were no significant differences in VAS scores after replacement between two groups (p > 0.05). The average range of motion preoperatively in group A was - 15.2-90.6°, which postoperatively increased to - 4.2-110.0°. Meanwhile, the KSS scores and average range of motion of the group A were better than those of the group B at each follow-up time after treatment. Arthroscopic debridement can decrease HO seen from postoperative X-rays, improve the function and range of motion, as well as the pain remission between two groups are comparable. Consequently, arthroscopic resection of HO after TKR is recommended as soon as there is aggravating joint stiffness.

Femoral anterior condyle height decreases as the distal anteroposterior size increases in total knee arthroplasty: A comparative study

PURPOSE

The anterior flange height of the current femoral component increases with an increasing distal femoral anteroposterior dimension. During total knee arthroplasty (TKA), we have observed that a large femur may have a thinner anterior condyle, whereas a small femur may have a thicker anterior condyle. The first purpose of this study was to examine whether the femoral anterior condyle height decreases as the distal femoral anteroposterior size increases and whether gender differences exist in anterior condyle height.

METHODS

A total of 1218 knees undergoing TKA intraoperative and computed tomography scans from 303 healthy knees were used to measure the anterior lateral condylar height (ALCH), anterior medial condylar height (AMCH), and the lateral anteroposterior (LAP) and medial anteroposterior (MAP) dimensions of distal femurs. The LAP and MAP measurements were used for adjustments to determine whether gender differences exist in anterior condyle heights. Linear regression analysis was performed to determine correlations between ALCH and LAP or between AMCH and MAP.

RESULTS

There were significant differences between males and females in ALCH in both the CT and TKA groups and AMCH in the CT group (all P<0.01). After adjusting for LAP and MAP, there were significant gender differences in the lateral and medial condylar heights in both groups (P<0.01). There were significant negative correlations between ALCH and LAP values and between AMCH and MAP values in both CT and TKA measurements, with the LAP and MAP values increasing as ALCH and AMCH decreased.

CONCLUSIONS

The results demonstrate that femoral anterior condylar height decreased with increasing anteroposterior dimension in both the medial and lateral condyle. In addition, this study also showed that anterior condylar heights are highly variable, with gender differences. The data may provide an important reference for designing femoral anterior flange thickness to precisely match the natural anterior condylar anatomy.

Patient height is a predictive factor for good postoperative knee flexion after cruciate-retaining total knee arthroplasty with GRADIUS design

BACKGROUND

A gradually reducing radius (GRADIUS) design implant can facilitate a smooth transition from stability through full range of motion in total knee arthroplasty (TKA). Nonetheless, patient-specific factors associated with good knee flexion remain unclear.

OBJECTIVE

This study aimed to determine the factors associated with good knee flexion after cruciate-retaining TKA with a GRADIUS prosthesis in an Asian population.

METHODS

This retrospective study included 135 patients that were stratified according to postoperative knee flexion angle (KFA) into Group F (⩾ 120∘; 85 patients [63.2%]) and Group NF (< 120∘; 50 patients [36.8%]).

RESULTS

Patients in Group F were taller and had a lower body mass index (BMI) smaller preoperative hipkneeankle angle and better preoperative extension and flexion angle than Group NF patients. The multivariable analysis revealed that patients' height (odds ratio [OR]: 1.07, P= 0.0150), BMI (OR: 0.85, P= 0.0049), and preoperative flexion angle (OR: 1.06, P= 0.0008) predicted good KFA. The ROC curve analysis showed that the cutoff values of a good KFA were height 155.1 cm, BMI 22.1 kg/m2, and preoperative KFA 120∘.

CONCLUSIONS

Patient height, BMI, and preoperative KFA were independent factors affecting good postoperative KFA in patients of Asian descent who underwent cruciate-retaining TKA with a GRADIUS design.

Anatomic Referencing Restores the Anatomy of the Distal Femur with Less Compromise

Historically, anterior referencing and posterior referencing are two specific techniques that surgeons can use for proper sizing of the femoral component in total knee arthroplasty (TKA). In this review, we introduce the concept of "anatomic referencing" which has become useful with more incremental sizes of the femoral component to more perfectly match the native anatomy of each patient and reduce overstuffing of the patellofemoral joint and medial-lateral (ML) overhang. Fifty consecutive TKA cases were reviewed where the novel anatomic referencing technique was used. Lateral radiographic projections were obtained preoperatively and postoperatively. The posterior condylar offset (PCO) was evaluated on the lateral radiographs by measuring the distance between the tangent line of the femoral diaphysis posterior cortex and the posterior condylar margin. PCO ratio (PCOR) was calculated by dividing the PCO by the distance between the posterior condylar border and a tangent line along the anterior cortex of the femoral diaphysis. Forty-five patients (50 TKAs) were reviewed. Average age of the patients was 70.34, range: 47-91. There were 19 males and 26 females reviewed in this series. On average, the delta PCOR was 0.022 (standard deviation = 0.032; min: -0.049, max: 0.082). When grouping our results into three main groups: < -0.03, -0.03 to 0.03, and > 0.03, we found that 62% fell within the -0.03 to 0.03 range. There was no statistically significant difference in delta PCOR between standard and narrow implants (p = 0.418). The proposed novel anatomic referencing technique has allowed for proper sizing of patients' femurs in the anteroposterior and ML direction while avoiding component overhang or the need for component downsizing to obtain a proper ML fit. This radiographic review confirmed this to be a highly accurate and reproducible technique.

Distal femur morphology and the suitability of standard guides for knee arthroplasty in the Turkish population

OBJECTIVE

The aim of this study was to evaluate the posterior condylar angle (PCA) and condylar twist angle (CTA) of the distal femur in the Turkish population and its concordance with the current standard prosthesis guides used in total knee arthroplasty (TKA).

METHODS

Two hundred and forty knees of 120 Turkish subjects (60 male and 60 female) were included in this study. PCA, CTA, femoral mediolateral lengths (fML), medial femoral anteroposterior lengths (fMAP), lateral femoral anteroposterior lengths (fLAP), distances between the trochlear groove and fMAP (DBTG-fMAP), distances between the trochlear groove and fLAP (DBTG-fLAP), medial posterior condylar cartilage thickness (MPCCT) and lateral posterior condylar cartilage thicknesses (LPCCT) were measured on magnetic resonance imaging (MRI).

RESULTS

The median CTA was 7° (range: 0°-13.0°) and the median PCA was 4° (range 0°-11.0°) (P < .0001). The median fML was 79.5 mm (range: 65.7-98.9). The median length of the fMAP was 58.2 mm (range: 46.8-69.0) and the median length of fLAP was 58.2 mm (range: 48.4-73.0). The DBTG-fMAP was 15.2 mm (range: 5.2-23.2), and DBTG-fLAP length was 21.9mm (range: 16.4-29.4). The median MPCCT and LPCCT were 2.4 mm (range: 1.6-3.6) and 2.3 mm (range: 1.2-2.8), respectively. The intraclass correlation coefficient for quantifying interobserver and intraobserver reliability showed excellent agreement regarding the PCA and CTA.

CONCLUSION

This study has shown us that PCA and CTA may be higher in the Turkish population. Although it is not known whether these results have any clinical utility, it may be useful for surgeons to keep this in mind to prevent femoral component malposition.

LEVEL OF EVIDENCE

Level IV, Diagnostic Study.

Robotic arm-assisted unicondylar knee arthroplasty resulted in superior radiological accuracy: a propensity score-matched analysis

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) is an effective surgical treatment for medial compartment arthritis of the knee, yet surgical outcomes are directly related to surgical execution. Robotic arm-assisted surgery aims to address these difficulties by allowing for detailed preoperative planning, real-time intraoperative assessment and haptic-controlled bone removal. This study aimed to compare the clinical and radiological outcomes between conventional manual mobile bearing and robot arm-assisted fixed bearing medial UKA in our local population.

MATERIALS AND METHODS

This is a retrospective case-control study of 148 UKAs performed at an academic institution with a minimum of 1-year follow-up. 74 robotic arm-assisted UKAs were matched to 74 conventional UKAs via propensity score matching. Radiological outcomes included postoperative mechanical axis and individual component alignment. Clinical parameters included a range of motion, Knee Society knee score and functional assessment taken before, 6 and 12 months after the operation.

RESULTS

Robot arm-assisted UKA produced a more neutral component coronal alignment in both femoral component (robotic -0.2 ± 2.8, manual 2.6 ± 2.3; P = 0.043) and tibial component (robotic -0.3 ± 4.0, manual 1.7 ± 5.3; P < 0.001). While the postoperative mechanical axis was comparable, robot arm-assisted UKA demonstrated a smaller posterior tibial slope (robotic 5.7 ± 2.7, manual 8.2 ± 3.3; P = 0.02). Clinical outcomes did not show any statistically significant differences.

CONCLUSION

Compared with conventional UKA, robotic arm-assisted UKA demonstrated improved component alignment and comparable clinical outcomes. Improved radiological accuracy with robotic-arm assistance demonstrated promising early results.

Reliability of the TT-TG Index Versus TT-TG Distance on MRI: Morphometric Analyses in Asian Children and Adolescents

Background

The tibial tuberosity-trochlear groove (TT-TG) distance measured on magnetic resonance imaging (MRI) is commonly used to decide the treatment for patellar instability; however, the patient's joint size is not considered in this measurement. The TT-TG index has been proposed as a knee size-adjusted measurement for tibial tuberosity location.

Purpose

To evaluate the reliability of the TT-TG index compared with the TT-TG distance by analyzing variations in measurement according to age and sex in a pediatric Asian population.

Study Design

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

Methods

A total of 698 knee MRI scans were collected in patients between 4 and 18 years of age who did not have any patellofemoral problems. Patient age, sex, height, and weight were recorded. The scans were divided into 5 groups according to patient age (4-6 years, 46 scans; 7-9 years, 56 scans; 10-12 years, 122 scans; 13-15 years, 185 scans; and 16-18 years, 289 scans); MRI scans were also divided by sex (497 male, 201 female). Three independent observers measured the TT-TG distance and TT-TG index on each scan, and age- and sex-based differences in the measurements were evaluated after adjusting for body mass index (BMI). The reliability of the measurements was calculated with the intraclass correlation coefficient (ICC).

Results

Good to excellent inter- and intraobserver agreement was found for TT-TG distance (ICC, 0.74) and TT-TG index (ICC, 0.88). The TT-TG distance was significantly different among the groups and increased with age, while variations in the TT-TG index were minimal between age groups and sexes. This finding was also consistent after compensating for the effect of BMI.

Conclusion

The TT-TG distance changed with age, while the TT-TG index was relatively constant. Therefore, the TT-TG index may be more reliable and effective for diagnosing and planning treatment, especially in children and adolescents.

Does Matching Femoral Size and Shape Improve Bone Fit and Patient-reported Outcomes in TKA? A Matched Controlled Study

BACKGROUND

Some researchers have suggested that achieving good component coverage over the host bone during TKA (while avoiding implant overhang) may help achieve durable implant fixation and may be associated with better outcomes scores. However, the evidence about this is limited and contradictory. Contemporary morphometric TKA includes a wide array of components with various shapes and sizes, based on large anatomic databases and specific software that simulates bone cuts. Morphometric tibial components have shown improved bone coverage and better clinical outcomes than standardized implants, but the role of morphometric femoral components in bone coverage has not been studied precisely.

QUESTIONS/PURPOSES

In a retrospective, controlled study that used patient matching, we asked: (1) Does the use of a contemporary morphometric component with more available sizes provide better femoral component fit and bone coverage than an earlier design with fewer sizes? (2) Are component fit and the presence of component overhang or underhang associated with different Knee Society Score (KSS) or Knee Injury and Osteoarthritis Outcome Score (KOOS) for Joint Replacement?

METHODS

From 2012 to 2013, we performed 403 TKAs according to the following criteria: TKA performed for primary tricompartmental arthritis of the knee; varus, valgus, and flexion deformity less than 15°; and age between 18 and 85 years on the day of surgery. Among these 403 TKAs, 237 were performed using a morphometric implant and 166 with the earlier nonmorphometric implant. At 2 years of follow-up, 3% of patients in the morphometric group and 5% in the nonmorphometric group were lost to follow-up. Based on age, BMI, gender, and preoperative KSS and KOOS, two groups of 30 patients were matched in a 1:1 ratio from this longitudinally maintained database. Clinical outcomes were measured preoperatively and at a minimum follow-up of 2 years in both groups, using the KSS and KOOS. We evaluated postoperative CT images for each patient to analyze femoral implant rotation, bone coverage, and overhang and underhang status.

RESULTS

The overhang status was similar between the two groups (23% had an overhang component in the morphometric knee group and 27% had an overhang component in the nonmorphometric knee group), and overhang was most frequently found in the lateral distal zone and medial anterior chamfer. Better cortical bone coverage was found in the morphometric knee group, with a thinner bone margin between the component edge and cortical border (morphometric group: 3 mm versus nonmorphometric knee group: 5 mm; p = 0.01). In general, there were few between-group differences in terms of patient-reported outcomes; of the seven metrics we analyzed, only the KSS favored the morphometric knee implant by a margin larger than the minimum clinically important difference (KSS mean difference: 21 points for the morphometric knee group; p < 0.05). Overhang of the femoral component of > 2 mm was associated with poorer KOOS, but not KSS, whereas a thinner bone margin had a beneficial impact on pain and global clinical scores (KOOS and KSS: p < 0.05).

CONCLUSION

The use of a morphometric femoral component design showed slightly improved bone fit and pain score according to the KSS at midterm follow-up compared with earlier implants with fewer sizes. Overhang > 2 mm was associated with worse KOOS. The tendency toward better outcomes in morphometric implants warrants longer-term evaluation before any definite conclusions about the association between bone fit and clinical results can be drawn.Level of Evidence Level III, therapeutic study.

Clinical significance of distal femur morphology in a healthy Mongolian youth population

Morphological parameters of knee joint are related to race and nationality. At present, knee prosthesis come from white male population. Due to the mismatch between the prosthesis and other ethnic groups, the prosthesis life span is reduced, revision surgery and the patients' economic burden are increased. There is no data of the Mongolian ethnic group. In order to treat patients more accurately, we measured the Mongolian data of the femoral condyle. A total of 122 knee joints were scanned in 61 volunteers (21 males and 40 females) with an average age of 23.259 ± 1.395 years. The Mimics software was used to reconstruct the 3D image and measure the data of each line. The data were analyzed by statistical methods such as t test, and P < 0.05 was taken as the significant. 122 normal femoral condyle data were obtained. The mean transverse diameter of femoral condyle is 76.472 ± 5.952 mm, medial condyle is 29.259 ± 11.461 mm, and the sagittal diameter of the medial condyle was 56.758 ± 4.163 mm. The transverse diameter of the lateral femoral condyle is 29.388 ± 3.157 mm, the sagittal diameter of the lateral condyle is 58.937 ± 3.527 mm and the femoral plane rate is 1.264 ± 0.072. (1) There was no statistical significance in the left and right knee joint data (P > 0.05). (2) The different genders data of femoral condyle were statistically significant (P < 0.05). (3) Compared with other nationalities and races, the data of femoral condyle are different. (4) There are differences between femoral surface ratio and mainstream prosthesis data.

Sexual dimorphism of the posterior condylar offset of the femur and the medial posterior slope of the tibia in non-arthritic knees of Egyptian adults: an MRI study

BACKGROUND

The aim of this magnetic resonance imaging (MRI) study was to investigate controversial sexual dimorphism of the posterior condylar offset of the femur (the offset) and the posterior slope of the tibia (the slope) in non-arthritic knees of Egyptian adults.

METHODS

On 100 male and 100 female MRIs of non-arthritic knees, linear measurements of the distal part of the femur (the offset) and the angular measurements of the proximal part of the tibia (the slope) were performed and compared regarding sex and ethnicity. The intraclass correlation coefficient (ICC) was used to test the interrater agreement.

RESULTS

Both offsets and the lateral offset ratio were larger in males (p < 0.001), the medial offset ratio, and the medial slope in females (p from < 0.001 to 0.007), whereas the lateral slope was sex-free (p = 0.41). Irrespective of sex, however, the medial offset with its ratio, and the medial slope were larger than their counterparts (p < 0.001). Our means of the offsets, their ratios, and the slopes mostly differed from those of other ethnicities (p from ≤ 0.001 to 0.004). ICCs > 0.8 proved MRI's precision was high.

CONCLUSION

There was a sexual dimorphism of both the offset and the medial slope in non-arthritic knees of Egyptian adults. We believe future designs of knee implants should consider these differences in order to improve postoperative range of motion and patients' satisfaction after total knee arthroplasty. Level of evidence Level III Retrospective Cohort Study. Trial registration ClinicalTrials.gov identifier: NCT03622034, registered on July 28, 2018.

Estimating aspect ratio of the distal femur and proximal tibia in the Emirati population from MRI scans of the knee: a preliminary experience

Size and shape of knee implants play an important role in the success of total knee arthroplasty. Several studies have identified anthropometric differences of the distal femur and proximal tibia between the genders and ethnicities. Ill-fitting prosthesis can cause overhang or under-fit resulting in persistence of pain, periprosthetic fracture and decreased range of motion. The purpose of this study was to estimate the aspect ratio of distal femur and proximal tibia in the Emirati population and determine whether gender differences exist within this group. Magnetic resonance imaging datasets of unilateral knees scans performed on adult Emirati patients at a tertiary care hospital were retrospectively examined. Knee parameters were obtained from 65 males and 46 females (n = 111). Females showed significantly smaller AP and ML dimensions of distal femur and lower aspect ratios compared to males (p < 0.001). Proximal tibial dimensions (AP and ML) of Emirati women are also significantly smaller compared to men. However, aspect ratio of proximal tibia did not show gender variation (p = 0.956) within the Emirati population. Emirati knees showed significant gender differences in bony dimensions and aspect ratio of the knee, and also have smaller aspect ratios when compared with most other population groups.

Correlation between tibial valgus deformity and aspect ratio of resected tibial surface in female Chinese patients undergoing total knee arthroplasty

Background

Morphology of the resected tibial surface is the reference for tibial component design, selection, and implantation in total knee arthroplasty (TKA). This comparative study sought to answer whether valgus deformity of the tibia would affect the morphology of the resected tibial surface in TKA.

Methods

Thirty-one female Chinese patients with valgus tibias were retrospectively and consecutively identified from a single-center registration database. Thirty-one patients with well-aligned tibias were matched in terms of gender, height, and weight. Weight-bearing full-length radiographs and computed tomography images of the whole lower limb were obtained for every case. Tibial resection was mimicked perpendicular to the mechanical axis of the tibia in the frontal plane with 3° of posterior slope and a cut level individualized by the actual intraoperative cut. On the resected surface, mediolateral dimension (MLD), medial anteroposterior dimensions (mAPD), and lateral anteroposterior dimensions (lAPD) were measured, and aspect ratios (AR) were calculated. We compared the AR between the two groups.

Results

The aspect ratio of resected tibial surface positively correlated with tibial valgus alignment. Patients with valgus tibias had significantly smaller AR (MLD/mAPD) for the medial plateau (1.50 ± 0.06 vs. 1.54 ± 0.07, P = 0.032). However, the AR for the lateral plateau was similar between the two groups (1.63 ± 0.08 vs. 1.65 ± 0.07, P = 0.328).

Conclusion

This difference in morphology of resected tibial surface between valgus and well-aligned tibias should be considered in tibial component design, as well as in the selection and placement of TKA implants for knees with valgus tibias.

Statistical modeling: Assessing the anatomic variability of knee joint space width

Population-based knee joint space width (JSW) assessments are promising for the prevention and early diagnosis of osteoarthritis. This study aimed to establish the statistical shape and alignment model (SSAM) of knee joints for assessing anatomic variation in knee JSW in the healthy Chinese male population. CT scans of asymptomatic knee joints of healthy male participants (n = 107) were collected for manual segmentation to create mesh samples. The as-scanned positional error was reduced by a standard processing flow of deformable mesh registration. Principal component analysis (PCA) was performed to create a tibiofemoral SSAM that was trained on all mesh samples. The anatomic variability of the JSW in the healthy Chinese male population was then assessed using the SSAM with regression analysis and 3D analysis by color-coded mapping. Almost all PCA modes had a linear influence on the anatomic variation of the medial and lateral JSW. The JSW variability within the SSAM was mainly explained by mode 1 (45.1 % of variation), demonstrating that this mode had the greatest influence on JSW variation. 3D assessment of the JSW showed that the minimum medial JSW varied from 2.76 to 3.23 mm, and its site shifted a short distance on the medial tibial plateau. The root-mean-square fitting and generalization errors of the SSAM were below 1 mm. This study will benefit the design and optimization of prosthetic devices, and may be applicable to the prevention and early diagnosis of osteoarthritis.

The 50 most cited studies on posterior tibial slope in joint preserving knee surgery

PURPOSE

To determine the 50 most cited studies on posterior tibial slope (PTS) in joint preserving knee surgery and assess their level of evidence, objective study quality scores as well as to examine whether the study quality correlated with the citation count and citation density in the top 50 list.

METHODS

A literature search on Web of Science was performed to determine the 50 most cited studies on the topic of PTS in joint preserving knee surgery between 1990 and 2022. The studies were evaluated for their bibliographic parameters, level of evidence rating (LOE), citation counts, the Modified Coleman Methodological Score (MCMS), the Methodological Index for Non-Randomized Studies (MINORS), and the Radiologic Methodology and Quality Scale (MQCSRE).

RESULTS

Of the top 50 list, 16 studies were published in the American Journal of Sports Medicine. A total of 23 studies were produced in the United States (46%). Of 10 different study types, case control studies (n = 16, 32%) and cadaveric studies (n = 10, 20%) were most common. 15 studies (30%) were purely radiological studies. 6 studies were level II (12%), 23 level III (46%), 15 level IV (30%), and 6 level V studies (12%), respectively. The number of citations ranged from 42 to 447 (mean 105.6 ± 79.2 citations) and showed a mean citation density of 10.3 ± 5.2, composed of the decades 1994 - 2000 (8.3 ± 4.1), 2001 - 2010 (11.1 ± 5.9), 2011 - 2019 (10.1 ± 5.1). Mean quality scores were 55.9 ± 13.0 for MCMS (n = 18), 14.5 ± 3.2 for MINORS (n = 18) and 18.1 ± 3.7 for MQCSRE (n = 20), respectively. High citation counts did not correlate with higher study quality scores (p > 0.05). Radiological studies were not significantly cited more often than non-radiological studies (mean 116.9 ± 88.3 vs. 100.8 ± 75.8 citations; p > 0.05).

CONCLUSION

In joint preserving knee surgery, the 50 most cited studies on PTS did not represent a ranking of the highest methodological quality scores. Citation counts and citation density over the past three decades did not significantly differ, even though the number of articles in the presented list multiplied over the same period. This list can serve as a reference tool for orthopedic surgeons aiming to review PTS literature.

Evaluation of Anthropometric Measurements of the Aspect Ratio of Knee in Indian Population and its Correlation with the Sizing of Current Knee Arthroplasty System

BACKGROUND

Most of the commercially available TKR implants are designed for western populations, which are known to have larger build and stature compared to Asian counterparts often leading to mismatch between resected bony surfaces and implant components. There is paucity of morphometric data of distal femur and proximal tibia in the Indian population. Thus, it becomes important to obtain anthropometric data to achieve the best stability and long-term success of implant.

MATERIALS AND METHODS

Intraoperative morphological measurements of 100 knees (59 female and 41 males) were done using vernier calliper during TKR. The anteroposterior (AP) and mediolateral (ML) dimensions of cross-section of the femur and tibia were noted before bony resection. The aspect ratios were calculated and compared with that of implant used (DePuy, Stryker, Maxx).

RESULTS

We have found that Indian males have larger dimensions of distal femur as well as proximal tibia than females. There exists some degree of mismatch in patients' dimensions and the sizes of all the three commercially available implant system as well their aspect ratios.

CONCLUSION

Specific designing of implants with dimensions in accordance with the morphometric measurements of Indian population should be done. Also gender specific implant designing should be done.

Does One Size Really Fit All? Morphometric Analysis of Distal Femur and Proximal Tibia in an Ethnic Indian Population and Correlation to the Sizing of Existing Total Knee Arthroplasty Implants

BACKGROUND

Total knee arthroplasty (TKA) has been proven to be a highly efficacious procedure for patients with end-stage osteoarthritis who have persistent symptoms not managed by conservative treatment. A large percentage of standard commercially available total knee arthroplasty (TKA) implants are imported and designed based on morphometric data of Western populations, which are known to have a larger build compared to their Asian counterparts. Hence, these prostheses may sometimes not be the best fit for Indian patients. We conducted this study to examine the anthropometry of osteoarthritic knees of Indian patients, analyze anatomical differences between males and females, and compare these measurements with commercially available five TKA implants.

METHODS

Morphometric data were collected from 150 Indian patients with osteoarthritis of the knee using computed tomography (CT) scans. The mediolateral (ML) and anteroposterior (AP) dimensions of the distal femur and proximal tibia were measured, and aspect ratios (ML/AP) were calculated. These measurements were correlated with current commercially available implant sizes.

RESULTS

We examined CT scans of 100 female and 50 male patients' knees with a combined average age of 58.2 ± 7.5 years. The mean mediolateral and anteroposterior dimensions of the distal femur for Indian knees were 74.5 ± 5.8 mm and 58.0 ± 4.2 mm, respectively, whereas for the proximal tibia, 69.1 ± 5.5 mm and 43.8 ± 3.6, respectively. The mean aspect ratio for the femur was 129.0 ± 6.0 and for the tibia was 158.1 ± 9.1. Male dimensions were found to be greater than female dimensions in all measured aspects of the distal femur and proximal tibia for the Indian population. However, the aspect ratio of the tibia was not found to vary with gender. When compared with the dimensions of other ethnic groups, the size of Indian knees was found to be smaller than Caucasians.

CONCLUSIONS

There is a mismatch between the anatomy of Indian knees and currently available TKA implants, and these implants may have drawbacks when implanted in Indian patients. The obtained anthropometric data may provide useful directions for designing TKA implants of more suitable sizes and aspect ratios for Indian patients.

Non-South East Asians have a better running economy and different anthropometrics and biomechanics than South East Asians

Running biomechanics and ethnicity can influence running economy (RE), which is a critical factor of running performance. Our aim was to compare RE of South East Asian (SEA) and non-South East Asian (non-SEA) runners at several endurance running speeds (10-14 km/h) matched for on-road racing performance and sex. Secondly, we explored anthropometric characteristics and relationships between RE and anthropometric and biomechanical variables. SEA were 6% less economical (p = 0.04) than non-SEA. SEA were lighter and shorter than non-SEA, and had lower body mass indexes and leg lengths (p ≤ 0.01). In terms of biomechanics, a higher prevalence of forefoot strikers in SEA than non-SEA was seen at each speed tested (p ≤ 0.04). Furthermore, SEA had a significantly higher step frequency (p = 0.02), shorter contact time (p = 0.04), smaller footstrike angle (p < 0.001), and less knee extension at toe-off (p = 0.03) than non-SEA. Amongst these variables, only mass was positively correlated to RE for both SEA (12 km/h) and non-SEA (all speeds); step frequency, negatively correlated to RE for both SEA (10 km/h) and non-SEA (12 km/h); and contact time, positively correlated to RE for SEA (12 km/h). Despite the observed anthropometric and biomechanical differences between cohorts, these data were limited in underpinning the observed RE differences at a group level. This exploratory study provides preliminary indications of potential differences between SEA and non-SEA runners warranting further consideration. Altogether, these findings suggest caution when generalizing from non-SEA running studies to SEA runners.

Anthropometric Comparison between Indian and Arabian Knees with Respect to Total Knee Replacement

Implants used for total knee replacement (TKR) in most Asian countries are not designed originally for the Asian population, and studies have shown anthropometric differences with respect to TKR among various ethnic groups. For this reason, implants designed for a specific population may not provide an anatomic fit when used in other populations. To avoid the consequences associated with such a misfit, the concept of ethnic-specific implant design is being introduced. In this study, the knee anthropometry of the Indian and Arabian patients was compared. They were operated with implants which were not ethnic-specific designs. Since the consequences associated with implant misfit apply equally to both the Indian and Arabian population, it is essential to compare the knee anthropometry of these two populations. Anthropometric measurements of the distal femur and proximal tibia of the Indian and Arabian knees were obtained intraoperatively using a Vernier caliper. Their respective aspect ratios (ARs) were calculated and statistically compared. It was found that the ARs of both tibia and femur of Indian and Arabian population did not show any statistical difference. There was no statistical difference between Indian and Arabian males (p = 0.345) and between Indian and Arabian females (p = 0.8210). However, a statistical difference in tibial AR (p-value = 0.049) and femoral AR (p-value = 0.003) was found significant when a comparison was made between the knees of Indian males and Indian females in the study. The above results suggested that TKR implants designed anatomically to suit the Indian population can also suit the Arabian population and vice versa. The obtained data can help implant designers to come up with ethnic-specific TKR implants.

Sexual dimorphism and racial diversity render bone-implant mismatch inevitable after off-the-shelf total knee arthroplasty: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to investigate the variability in femoral geometric ratios among knees of different sexes and races, and to appreciate whether the observed variability is accommodated by commonly implanted total knee arthroplasty (TKA) components. The hypothesis was that the anthropometric studies report considerable variability of femoral geometric ratios among sexes and races.

METHODS

This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) criteria. Two authors independently conducted an electronic search using MEDLINE^® and Embase^® on 6 July 2020 for clinical studies reporting on femoral geometric ratios among sexes and races. Femoral geometric ratios were graphically represented as means and 2 standard deviations, and compared to those of 13 commonly implanted femoral components.

RESULTS

A total of 15 studies were identified that reported on a combined total of 2627 knees; all reported the aspect ratio, and 2 also reported the asymmetry ratio and trapezoidicity ratio. Men had wider knees than women, and compared to Caucasian knees, Arabian and Indian knees were wider, while East Asian were narrower. There were no differences in asymmetry ratio between men and women, nor among Caucasian and East Asian knees. Men had more trapezoidal knees than women, and East Asian knees were more trapezoidal than Caucasian knees. The commonly implanted femoral components accommodated less than a quarter of the geometric variability observed among sexes and races.

CONCLUSION

Anthropometric studies reported considerable sexual dimorphism and racial diversity of femoral geometric ratios. Since a surgeon generally only uses one or a few TKA brands, bone-implant mismatch remains unavoidable in a large proportion of knees. These findings support the drive towards personalized medicine, and accurate bone-implant fit may only be achievable through customisation of implants, though the clinical benefits of custom TKA remain to be confirmed.

LEVEL OF EVIDENCE

IV.

Investigation of morphotypes of the knee using cluster analysis

BACKGROUND

Objects that manifest in several characteristic shapes, or morphotypes, are typically caused by some hidden variable. For example, the gender of a person influences the width of their pelvis. This is important when reconstructing natural shapes, e.g., in knee implant design. The aim of this study was to identify such morphotypes.

METHODS

This work investigated the shapes of roughly 1000 knee joints acquired from computed tomography, including the distal femur and proximal tibia. Two comprehensive feature sets were utilized to describe the bone shapes, one based on morphological measurements and the other on statistical shape model (SSM) weights. We normalized the data by size and performed a cluster analysis with different algorithms, namely k-means and high dimensional data clustering. The clusters were evaluated using several metrics.

RESULTS

The data showed a low tendency to form clusters. Only one of 12 experiments slightly exceeded the thresholds for actual clusters suggested by the literature. k-Means outperformed high dimensional data clustering in all cases.

CONCLUSION

After anisotropic normalization by size, which removes size and aspect ratio related differences, the data exhibited no morphotypes. This showed that there are no relevant hidden variables, e.g., gender, body type or ethnicity, which influence the shape of the knee joint. Instead, knee shape is highly individual. Investigating the three-dimensional shape, variations occur for a wide range of different shape parameters, not just for anterior-posterior and mediolateral size.

An automatic measurement system of distal femur morphological parameters using 3D slicer software

In the field of joint surgery, the computer-aided design of knee prostheses suitable for the Chinese population requires a large quantity of anatomical knee data. In this study, we propose a new method that uses 3D Slicer software to automatically measure the morphological parameters of the distal femur. First, 141 femur samples were segmented from CT data to establish the femoral shape library. Next, balanced iterative reducing and clustering using hierarchies (BIRCH) combined with iterative closest point (ICP) and generalised procrustes analysis (GPA) were used to achieve fast registration of the femur samples. The statistical model was automatically calculated from the registered femur samples, and an orthopaedic surgeon marked the points on the statistical model. Finally, we developed an automatic measurement system using 3D Slicer software, and a deformable model matching method was applied to establish the point correspondence between the statistical model and the other samples. By matching points on the statistical model to corresponding points in other samples, we measured all other samples. We marked six points and measured eight parameters. We evaluated the performance of automatic matching by comparing the points marked manually with those matched automatically and verified the accuracy of the system by comparing the manual and automatic measurement results. The results indicated that the average error of the automatic matching points was 1.03 mm, and the average length error and average angle error measured automatically by the system were 0.37 mm and 0.63°, respectively. These errors were smaller than the intra-rater and inter-rater errors measured manually by two different surgeons, which showed that the accuracy of our automatic method was high. Taken together, this study established an accurate and automatic measurement system for the distal femur based on the secondary development of 3D Slicer software to assist orthopaedic surgeons in completing the measurements of big data and further promote the improved design of Chinese-specific knee prostheses.

A novel radiological classification system of the distal femur

INTRODUCTION

In our previous studies, we were able to identify anatomical differences as a predictor for aseptic loosening following primary and revision surgery with the use of rotating hinge prosthesis. This study was performed to answer following question: can a novel radiological classification system of the distal femur be identified?

MATERIALS AND METHODS

A total of 200 patients who received standardized anteroposterior (AP) and lateral views of the knee joint were included in this study. On AP radiographs, we measured the distance between inner diameter of the femur at 20 cm proximally from the knee and at a point 2 cm proximally from the adductor tubercle. The ratio of the inner diameter of the femoral canal at 20 cm proximal of knee joint to the inner diameter of medullary canal at 2 cm proximal of adductor tubercle was used as a novel index ratio. Two observers blindly and independently reviewed the anteroposterior radiographs twice.

RESULTS

Three groups of anatomical classification can be constructed for each sex according to the 25th and 75th percentiles. A higher distribution of Type C was found in female patients. The median intra-observer reliability for rater 1 was 0.995 (IQR 0.994-0.997). We had also a high inter-observer reliability with ICC of 0.997 (95% CI 0.996-0.998).

CONCLUSIONS

The novel classification presents three different types of the knee joint for male and female patients. Type C has a wider inner diaphyseal diameter compared to Type A with a narrow inner diaphyseal diameter.

The Relationship of Transepicondylar Width with the Distal and Posterior Femoral Condyles and Its Clinical Implications: A Three-Dimensional Study

BACKGROUND

 Restoration of the anatomical joint line, while important for clinical outcomes, is difficult to achieve in revision total knee arthroplasty (rTKA) due to distal femoral bone loss. The objective of this study was to determine a reliable method of restoring the anatomical joint line and posterior condylar offset in the setting of rTKA based on three-dimensional (3D) reconstruction of computed tomography (CT) images of the distal femur.

METHODS

 CT scans of 50 lower limbs were analyzed. Key anatomical landmarks such as the medial epicondyle (ME), lateral epicondyle, and transepicondylar width (TEW) were determined on 3D models constructed from the CT images. Best-fit planes placed on the most distal and posterior loci of points on the femoral condyles were used to define the distal and posterior joint lines, respectively. Statistical analysis was performed to determine the relationships between the anatomical landmarks and the distal and posterior joint lines.

RESULTS

 There was a strong correlation between the distance from the ME to the distal joint line of the medial condyle (MEDC) and the distance from the ME to the posterior joint line of the medial condyle (MEPC) (p < 0.001; r = 0.865). The mean ratio of MEPC to MEDC was 1.06 (standard deviation [SD]: 0.07; range: 0.88-1.27) and that of MEPC to TEW was 0.33 (SD: 0.03; range: 0.25-0.38).

CONCLUSIONS

 Our findings suggest that the fixed ratios of MEPC to TEW (0.33) and that of MEPC to MEDC (1.06) provide a reliable means for the surgeon to determine the anatomical joint line when used in combination.

Anthropometry of the knee of the Turkish population and the comparison to implant sizes in total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is one of the most common orthopaedic surgical procedures in the advanced stages of knee arthritis.

OBJECTIVE

The purpose of this study was to define the sex differences in the Turkish population's morphological measurements of the distal femoral and proximal tibial surfaces that form the knee joint and to compare their compatibility with conventional prosthetic implants commonly used in TKA for advanced-stage knee arthritis.

METHODS

Anthropometric data for a total of 240 knees from 240 patients were measured using 3-dimensional computed tomography (3D CT). All morphological data were compared with the dimensions of four conventional knee prostheses commonly used in Turkey.

RESULTS

A comparison of the four tibial components revealed that the majority of female proximal tibias matched with smaller-sized tibial components, whereas those of males matched the larger sizes. Comparing the morphological data with similar values for the four femoral components currently used in Turkey, we found that all the prostheses had similar values.

CONCLUSION

The four conventional prosthetic brands included in this study matched the distal femoral dimensions of both sexes. On the other hand, we need smaller size tibial components for our female population.

Comparable incidence of periprosthetic tibial fractures in cementless and cemented unicompartmental knee arthroplasty: a systematic review and meta-analysis

PURPOSE

(I) To determine the incidence of periprosthetic tibial fractures in cemented and cementless unicompartmental knee arthroplasty (UKA) and (II) to summarize the existing evidence on characteristics and risk factors of periprosthetic fractures in UKA.

METHODS

Pubmed, Cochrane and Embase databases were comprehensively searched. Any clinical, laboratory or case report study describing information on proportion, characteristics or risk factors of periprosthetic tibial fractures in UKA was included. Proportion meta-analysis was performed to estimate the incidence of fractures only using data from clinical studies. Information on characteristics and risk factors was evaluated and summarized.

RESULTS

A total of 81 studies were considered to be eligible for inclusion. Based on 41 clinical studies, incidences of fractures were 1.24% (95%CI 0.64-2.41) for cementless and 1.58% (95%CI 1.06-2.36) for cemented UKAs (9451 UKAs). The majority of fractures in the current literature occurred during surgery or presented within 3 months postoperatively (91 of 127; 72%) and were non-traumatic (95 of 113; 84%). Six different fracture types were observed in 21 available radiographs. Laboratory studies revealed that an excessive interference fit (press fit), excessive tibial bone resection, a sagittal cut too deep posteriorly and low bone mineral density (BMD) reduce the force required for a periprosthetic tibial fracture to occur. Clinical studies showed that periprosthetic tibial fractures were associated with increased body mass index and postoperative alignment angles, advanced age, decreased BMD, female gender, and a very overhanging medial tibial condyle.

CONCLUSION

Comparable low incidences of periprosthetic tibial fractures in cementless and cemented UKA can be achieved. However, surgeons should be aware that an excessive interference fit in cementless UKAs in combination with an impaction technique may introduce an additional risk, and could therefore be less forgiving to surgical errors and patients who are at higher risk of periprosthetic tibial fractures.

LEVEL OF EVIDENCE

V.

Morphometric measurement of the proximal tibia to design the tibial component of total knee arthroplasty for the Thai population

Purpose

This study evaluates the morphology of the Thai proximal tibia based on three-dimensional (3D) models to design the tibial component.

Methods

The 3D models of 480 tibias were created using reverse engineering techniques from computed tomography imaging data obtained from 240 volunteers (120 males, 120 females; range 20–50 years). Based on 3D measurements, a digital ruler was used to measure the distance between the triangular points of the models. The morphometric parameters consisted of mediolateral length (ML), anteroposterior width (AP), medial anteroposterior width (MAP), lateral anteroposterior width (LAP), central to a medial length (CM), central to a lateral length (CL), medial anterior radius (MAR), lateral anterior radius (LAR), and tibial aspect ratio (AR). An independent t-test was performed for gender differences, and K-means clustering was used to find the optimum sizes of the tibial component with a correlation between ML length and AP width in Thai people.

Results

The average morphometric parameters of Thai proximal tibia, namely ML, AP, MAP, LAP, CM, and CL, were as follows: 72.52 ± 5.94 mm, 46.36 ± 3.84 mm, 49.22 ± 3.62 mm, 43.59 ± 4.05 mm, 14.29 ± 2.72 mm, and 15.28 ± 2.99 mm, respectively. The average of MAR, LAR, and AR was 24.43 ± 2.11 mm, 21.52 ± 2.00 mm, and 1.57 ± 0.08, respectively. All morphometric parameters in males were significantly higher than those of females. There was a difference between the Thai proximal tibia and other nationalities and a mismatch between the size of the commercial tibial component and the Thai knee. Using K-means clustering analysis, the recommended number of ML and AP is seven sizes for the practical design of tibial components to cover the Thai anatomy.

Conclusion

The design of the tibial component should be recommended to cover the anatomy of the Thai population. These data provide essential information for the specific design of Thai knee prostheses.

Three-dimensional morphometric differences of resected distal femurs and proximal tibias in osteoarthritic and normal knees

BACKGROUND

There is a paucity of data concerning the morphological differences of resected distal femurs and proximal tibias in osteoarthritic (OA) and normal knees. The objective of this study was to determine whether morphometric differences in the surfaces of resected distal femurs and proximal tibias exist between OA and normal knees in a Chinese population.

METHODS

Ninety-four OA knees and ninety-five normal knees were evaluated in Chinese individuals. Computed tomography was used to measure the femoral mediolateral (fML), medial anteroposterior (fMAP), lateral anteroposterior (fLAP), medial condylar width (fMCW), lateral condylar width (fLCW), medial posterior condylar curvature radii (fMCR), lateral posterior condyle curvature radii (fLCR), fML/fMAP aspect ratio, tibial mediolateral (tML), middle anteroposterior (tAP), medial anteroposterior (tMAP), and lateral anteroposterior (tLAP) tML/tMAP aspect ratio to determine the morphologic differences between OA and normal knees.

RESULTS

The average fMCW and tMAP dimensions of OA knees were larger than those of normal knees in both male and female (p <0.05). The fMAP/fML aspect ratio and tMAP/tML aspect ratio were also significantly different in both sexs (p <0.05). OA knees have an oval-shaped distal femur with a wider ML length and more spherical-shaped proximal tibiae with relatively narrow ML dimensions.

CONCLUSIONS

The study revealed the morphological differences in fMCW, tMAP, fMAP/fML and tMAP/tML between OA and normal knees in both males and females. These findings may provide guidelines that can be used to design better knee implants that are more size-matched for OA knees.

The influence of posterior tibial slope on the mid-term clinical effect of medial-pivot knee prosthesis

OBJECTIVE

To evaluate the effect of posterior tibial slope (PTS) on the mid-term clinical outcome following a medial-pivot (MP) prosthesis.

METHOD

Two hundred thirty-three patients from The Affiliated Hospital of Qingdao University, who had undergone a total knee arthroplasty (TKA) with MP prosthesis between January 2015 and December 2015, were retrospectively included in this study. They were divided into 3 groups according to postoperative PTS: A ≤ 5°; B 5-7°; and C ≥ 7°. Multiple assessments were made on the patient postoperatively and recorded in the three groups, the measurements of this study included: the range of motion (ROM), knee scoring system (KSS), Western Ontario and McMaster universities osteoarthritis index (WOMAC), posterior condylar offset (PCO), joint line height, and postoperative complications.

RESULTS

The average post-operative ROM for groups B and C were 108° and 110° respectively; this was significantly higher than that of group A (98°, P < 0.001). The WOMAC scores of patients in group C were significantly lower than those in groups A and B (P < 0.05). However, there were no significant differences in KSS, PCO, and joint line height among the 3 groups (P > 0.05). Only 2 cases of postoperative complications occurred in group C, these were ameliorated after operation.

CONCLUSION

With an increase to PTS, the postoperative ROM can be significantly increased for the patient. However, the knee joint function will not be significantly improved, and the stability of knee joint will not be affected when within the limits of appropriate PTS.

ANATOMICAL STUDY OF THE POSTEROLATERAL LIGAMENT COMPLEX OF THE KNEE: LCL AND POPLITEUS TENDON

Objective:

To analyse the distances between the femoral insertions of the popliteus tendon (PT) and the lateral collateral ligament (LCL) through dissections of cadaveric specimens in a mixed population.

Methods:

Fresh cadavers were dissected, and the anthropometric data of all specimens were recorded. The distances from the origin of the PT to the LCL in the femoral region and the diameter of each structure were measured using a digital calliper.

Results:

In total, 11 unpaired knees were dissected, eight men and three women, with an average age of 71.5 ± 15.2 years, weight of 57.2 ± 15.6 kg, and a mean height of 170.5 ± 8.2 cm. The distance from the center of the femoral footprint of the LCL to the PT was 10.0 ± 2.4 mm. The distances between the edges closest to each other and those more distant from each other were 3.1 ± 1.1 mm and 16.3 ± 2.4 mm, respectively.

Conclusion:

The distance between the midpoints of the PT and the LCL in our mixed population is smaller than the distances often reported in the literature. PLC reconstruction with separate tunnels for the LCL and PT may not be technically possible for individuals of any population.Level of Evidence III, Diagnostic studies.

Evaluation of anatomical axis-joint center distance and anatomical axis-joint center ratio in distal femur and proximal tibia in coronal plane of Indian population

BACKGROUND

Radiographic evaluation of the anatomical geometry of the bone is important for executing reconstructive surgeries like deformity correction, limb lengthening and joint replacements. Various studies have been done in the past to define the anatomic placement of implant inside the bone. The aim of this study is to evaluate the distance between the anatomical axis and joint center of the distal femur (aJCD-f) and proximal tibia (aJCD-t) along with the ratio of anatomical axis-joint center distance of distal femur (aJCR-f) and proximal tibia (aJCR-t) of the skeletally mature individual of Indian population along with its application in day to day practice.

METHODS

Data is procured from the standard radiographs of the knee on large films. The anatomical axis is drawn on both sides of tibia and femur in a standard fashion. These lines intersect the horizontal drawn line at the intercondylar notch of femur and joint orientation line of the tibia. The aJCD-f, aJCD-t, aJCR-f, aJCR-t are then measured. Also the center of the inter-spinous distance of the tibia is measured from the anatomical axis (aSCD-t).

RESULTS

A total of 182 x-rays of skeletally mature individual were included with mean age of 46.35 ± 13.93 years. Of them 81 were males and 101 were females. There were 89 x-ray of left side and 93 x-ray of right side. The mean width of the femur at the intercondylar notch is found to be 76.78 mm (±7.40). The mean aJCD-f is found to be 3.87 mm (±2.44), aJCR-f to be 0.50 (±0.06). The mean width of the tibia is found to be 76.80 mm (±6.48). The aJCD-t is found to be 2.20 mm (±1.41), aJCR-t to be 0.50 (±0.03). The aSCD-t at the level of tibial spine is found to be -0.23 mm (±2.84). There was significant difference in the width of the femoral condyle of males 82.13 mm (±0.65) and females 72.48 mm (±0.55). Males showed mean aJCD-f of 3.59 mm (±2.42) and females showed 4.10 mm (±2.46). The aJCR-f is found to be significantly different between males 0.49 (±0.05) and females 0.51 (±0.07). There is significant difference between the width of the proximal tibia between males 80.83 mm (±0.68) and females 73.56 mm (±0.46). The aJCD-t of males and females is found to be 2.28 mm (±1.25) and 2.16 mm (±1.54) respectively. The aJCR-t is found to be significantly different between males 0.49 (±0.03) and females 0.50 (±0.04). While the mean distance of the anatomical axis from the lateral tibial spine is 0.23 mm lateral to the center of the inter-spinous distance and is found to be same in both males and females -0.23 mm (±2.84).

CONCLUSION

The coronal plane parameter like aJCD, aJCR of femur and tibia and aSCD-t of tibia can be a useful parameter to calculate in the 'real world' settings for reconstructive surgeries like deformity correction, nailing through the knee for femur and tibia as well as replacement surgeries around knee.

The patellofemoral morphology and the normal predicted value of tibial tuberosity-trochlear groove distance in the Chinese population

Background

Our objective was to obtain normal patellofemoral measurements to analyse sex and individual differences. In addition, the absolute values and indices of tibial tuberosity-trochlear groove (TT-TG) distances are still controversial in clinical application. A better method to enable precise prediction is still needed.

Methods

Seventy-eight knees of 78 participants without knee pathologies were included in this cross-sectional study. A CT scan was conducted for all participants and three-dimensional knee models were constructed using Mimics and SolidWorks software. We measured and analysed 19 parameters including the TT-TG distance and dimensions and shapes of the patella, femur, tibia, and trochlea. LASSO regression was used to predict the normal TT-TG distances.

Results

The dimensional parameters, TT-TG distance, and femoral aspect ratio of the men were significantly larger than those of women (all p values < 0.05). However, after controlling for the bias from age, height, and weight, there were no significant differences in TT-TG distances and anterior-posterior dimensions between the sexes (all p values > 0.05). The Pearson correlation coefficients between the anterior femoral offset and other indexes were consistently below 0.3, indicating no relationship or a weak relationship. Similar results were observed for the sulcus angle and the Wiberg index. Using LASSO regression, we obtained four parameters to predict the TT-TG distance (R² = 0.5612, p < 0.01) to achieve the optimal accuracy and convenience.

Conclusions

Normative data of patellofemoral morphology were provided for the Chinese population. The anterior-posterior dimensions of the women were thicker than those of men for the same medial-lateral dimensions. More attention should be paid to not only sex differences but also individual differences, especially the anterior condyle and trochlea. In addition, this study provided a new method to predict TT-TG distances accurately.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04454-8.

Clinical and Radiological Outcomes after Knee Arthroplasty with Patient-Specific versus Off-the-Shelf Knee Implants: A Systematic Review

Customised, patient-specific implants (PSI) manufactured based on computed tomography data are intended to improve the clinical outcome by restoring more natural knee kinematics as well as providing a better fit and a more precise positioning. The aim of this systematic review is to investigate the effect of these PSI on the clinical and radiological outcome compared to standard, off-the-shelf (OTS) implants. Thirteen comparative studies including a total of 2127 knee implants were identified. No significant differences in clinical outcome assessed with the range of motion, the Knee Society Score (KSS), and the Forgotten Joint Score (FJS-12) were found between PSI and OTS implants. PSI showed fewer outliers from the neutral limb axis and a better implant fit and positioning. Whether these radiological differences lead to long-term advantages in terms of implant survival cannot be answered based on the current data. Patients receiving PSI could be discharged home earlier at the same or at an even lower total cost. The effective overall superiority of PSI has yet to be proven in long-term studies.

Posterior Tibial Slope and a New Morphometric Method With Multiplanar Reconstruction Technique in a Turkish Sample

Aim: The posterior tibial slope (PTS) is important in planning many orthopedic procedures. The aim of the study is to outline a PTS measurement method using multiplanar reconstruction (MPR) in knee computed tomography (CT) images.

Methods: MPR reconstruction was performed on pre-captured CT angio images of 124 patients. A standard tibial axis was created. Then, using reference points, the PTS was measured separately for the medial PTS (MPTS) and lateral PTS (LPTS). To identify an intra- and interobserver error, the technical error of measurement (TEM), relative TEM (rTEM), and coefficient of reliability (R) of the measurement were analyzed.

Results: The study enrolled 124 patients (88 males, 36 females) from 18 to 92 years old. The average MPTS 8.63 ± 2.7° and LPTS 7.77 ± 3.1° were significantly different (p < 0.05). However, there was no difference between the sexes (p = 0.52 for MPTS; p = 0.9 for LPTS). The R for intraobserver reliability was 0.942 for the MPTS and 0.943 for the LPTS, and that for interobserver reliability was 0.815 and 0.806, respectively.

Conclusions: PTS measurement from CT images appears advantageous as it eliminates measurement limitations due to tibial rotation and has high intra- and interobserver consistency.

Considerable inter-individual variability of tibial geometric ratios renders bone-implant mismatch unavoidable using off-the-shelf total knee arthroplasty: a systematic review and meta-analysis

PURPOSE

The purpose of this systematic review and meta-analysis was to investigate the variability in tibial geometric ratios among knees of different sexes and races to determine whether commercially-available tibial baseplates accommodate the morphologic diversity. The hypothesis was that anthropometric studies report considerable variability of tibial geometric ratios among sexes and races.

METHODS

This systematic review and meta-analysis was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) criteria. Two authors independently conducted an electronic search using MEDLINE^® and Embase^® on 28 January 2021 for clinical studies reporting on tibial geometric ratios. Tibial geometric ratios, as reported by the clinical studies, were represented by plotting their means and two standard deviations for comparison to two symmetric and two asymmetric commercially-available tibial baseplates.

RESULTS

A total of 27 articles that reported on a combined total of 20,944 knees were eligible for data extraction. Variation in tibial aspect ratios was equal among sexes. The greatest variation in aspect ratio was observed among East Asians, followed by Caucasians, African-Americans, Indian and Middle Easterns. The variation in tibial asymmetry ratio was larger among men compared to women. The greatest variation in asymmetry ratio was observed among African-Americans, followed by Caucasians, East Asians, Indian and Middle Easterns. Bone-implant mismatch of > 3 mm overhang or > 4 mm under-coverage with four commercially-available tibial baseplates occurred in large proportions of knees due to variations in aspect ratio (in 17-100% of knees) and asymmetry ratio (in 7-100% of knees).

CONCLUSION

Anthropometric studies reported considerable inter-individual variability of tibial geometric ratios, which exceeded effects of sexual dimorphism and racial diversity. Bone-implant mismatch may be unavoidable in a large proportion of knees, when considering that a surgeon generally only uses one or a few TKA brands. These findings support the drive towards patient-specific implants to potentially achieve accurate bone-implant fit by implant customisation.

LEVEL OF EVIDENCE

IV.

Age, gender, height and weight in relation to joint cartilage thickness among school-aged children from ultrasonographic measurement

BACKGROUND

Among school-age children, the decrease of cartilage thickness (Cth) with increasing age is well known. However, the influence of body mass index (BMI), height or weight on Cth has not been revealed. Here in, we aim to establish an age- and gender-specific Cth standard reference among Asians and investigate the possible prestige of BMI, height and weight.

METHODS

A cross-sectional study was performed in healthy Asian children. Bilateral knees, ankles, wrists, second metacarpophalangeals (MCPs) and proximal interphalangeals (PIPs) were measured using ultrasound. The children's height, weight and BMI were also recorded for later adjustment.

RESULTS

A total of 200 school age Asian children (including 86 girls and 114 boys, aged between 5 to 13 years-old) were investigated. Cth differences were observed in the knees, ankles, wrists, MCPs and PIPs between sexes (p < 0.05), with girls having thinner cartilage thickness. While Cth decreases with increasing age (p < 0.0001, 0.039, 0.001, 0.023, 0.091 in girls' knees, ankles, wrists, MCPs and PIPs and p = 0.002, 0.001, < 0.0001, 0.001, 0.045 in boys', respectively). Our data showed that weight, height and BMI are not the main factors contributing to Cth. A formula to calculate gender-specific cartilage thickness for Asian school age children is suggested. There was no difference in Cth after adjusting for height or weight between Asian or Caucasian group.

CONCLUSIONS

A formula to calculate gender-specific cartilage thickness for Asian school age children is suggested. Height, weight and BMI were not the major contributor for Cth among school age children.

Coronal and axial alignment relationship in Caucasian patients with osteoarthritis of the knee

Individualized pre-operative assessment of the patterns of the lower extremity anatomy and deformities in patients undergoing total knee arthroplasty seems essential for a successful surgery. In the present study, we investigated the relationship among the coronal alignment and the rotational profile of the lower extremities in the Caucasian population with end-stage knee osteoarthritis. We conducted a prospective study of 385 knees that underwent a pre-operative three-dimensional computed tomography-based model. The lower extremity alignment was determined (mechanical tibiofemoral or hip-knee-ankle angle, supplementary angle of the femoral lateral distal angle, and proximal medial tibial angle). For each case, the femoral distal rotation (condylar twist angle), the femoral proximal version, and the tibial torsion were determined. As the coronal alignment changed from varus to valgus, the femoral external rotation increased (r = 0.217; p < 0.0005). As the coronal alignment changed from varus to valgus, the external tibial torsion increased (r = 0.248; p < 0.0005). No correlation was found between the global coronal alignment and the femoral version. The present study demonstrates a linear relationship between the coronal alignment and the rotational geometry of the distal femur. This correlation also occurs with the tibial torsion. Perhaps outcomes of total knee arthroplasty surgery might be improved by addressing these deformities as well.

Lateral Unicompartmental Knee Arthroplasty

Lateral unicompartmental knee arthroplasty affords excellent functional results and implant survivorship for properly selected patients. More high-quality studies are necessary to determine whether expanded indications for medial unicompartmental knee arthroplasty also apply to lateral unicompartmental knee arthroplasty. Operative adjuncts such as robotics, custom implants, and navigation technology hold promise in minimizing the technical burden and unfamiliarity of lateral unicompartmental knee arthroplasty. Improvements in lateral-specific implants may translate to operational efficiency and improved outcomes, but few lateral-specific implants currently exist. Mobile-bearing devices have increased rates of failure due to bearing dislocation, and further studies are warranted to evaluate this complication with newer designs. Future registry and cohort studies should show medial unicompartmental knee arthroplasty and lateral unicompartmental knee arthroplasty separately to allow for better understanding of the nuances and technical differences between these uniquely different procedures.

To Predict the Length of Hospital Stay After Total Knee Arthroplasty in an Orthopedic Center in China: The Use of Machine Learning Algorithms

Background and Objectives: Total knee arthroplasty (TKA) is widely performed to improve mobility and quality of life for symptomatic knee osteoarthritis patients. The accurate prediction of patients' length of hospital stay (LOS) can help clinicians for rehabilitation decision-making and bed assignment planning, which thus makes full use of medical resources.

Methods: Clinical characteristics were retrospectively collected from 1,298 patients who received TKA. A total of 36 variables were included to develop predictive models for LOS by multiple machine learning (ML) algorithms. The models were evaluated by the receiver operating characteristic (ROC) curve for predictive performance and decision curve analysis (DCA) for clinical values. A feature selection approach was used to identify optimal predictive factors.

Results: The areas under the ROC curve (AUCs) of the nine models ranged from 0.710 to 0.766. All the ML-based models performed better than models using conventional statistical methods in both ROC curves and decision curves. The random forest classifier (RFC) model with 10 variables introduced was identified as the best predictive model. The feature selection indicated the top five predictors: tourniquet time, distal femoral osteotomy thickness, osteoporosis, tibia component size, and post-operative values of Hb within 24 h.

Conclusions: By analyzing clinical characteristics, it is feasible to develop ML-based models for the preoperative prediction of LOS for patients who received TKA, and the RFC model performed the best.

Three-Dimensionally-Printed Joint-Preserving Prosthetic Reconstruction of Massive Bone Defects After Malignant Tumor Resection of the Proximal Tibia

Joint-preserving prosthetic reconstruction for massive bone defects has the potential to be a new and revolutionary treatment option. In this paper, we discuss the case of a 30-year-old female patient who presented with pain and swelling around the knee for three months. The patient underwent this procedure. Postoperative patient satisfaction, pain scores, and range of motion results were found to be promising. We believe that this method has the potential to be the next stage in the quest for better treatment options for this condition.

Benefits of early ambulation within 24 h after total knee arthroplasty: a multicenter retrospective cohort study in China

BACKGROUND

Postoperative care has been evolving since the concept of enhanced recovery after surgery (ERAS) was introduced in China. This study aimed to evaluate the effects of early ambulation within 24 h after unilateral total knee arthroplasty (TKA) on postoperative rehabilitation and costs in a Chinese population.

METHODS

This cohort study of patients with knee osteoarthritis who had undergone TKA at 24 large teaching hospitals between January 2014 and November 2016 involved 2687 patients who began ambulating within 24 h (Group A) and 3761 who began ambulating later than 24 h (Group B). The outcome measurements, such as length of stay (LOS), total hospitalization costs, dynamic pain level, knee flexion range of motion (ROM), results of the 12-Item Short Form Survey (SF-12), incidence of thromboembolic events and other complications, were recorded and compared.

RESULTS

The early ambulation group (Group A) had a shorter LOS and lower hospitalization costs and pain levels than the late ambulation group (Group B). There was a favorable effect in enhancing ROM for patients in Group A compared with patients in Group B. In Group A, patients had significantly higher postoperative SF-12 scores than those in Group B. The incidence of deep venous thrombosis (DVT) and pulmonary infection was significantly lower in Group A than in Group B. The incidence of pulmonary embolism (PE) and other complications did not differ between the two groups.

CONCLUSION

Early ambulation within 24 h after TKA was associated with reduced LOS, improved knee function, lower hospitalization costs and lower incidence of DVT and pulmonary infection in the Chinese population.