Are Korean Patients Different from Other Ethnic Groups in Total Knee Arthroplasty?

The Influence of Knee Phenotypes Based on Coronal Plane Alignment of the Knee on Intraoperative Soft Tissue Balance and Clinical Outcomes: Comparison between Kinematically and Mechanically Aligned Total Knee Arthroplasty

This study examined the impact of preoperative coronal plane alignment of the knee (CPAK) classification on intraoperative soft tissue balance and postoperative clinical outcomes in patients undergoing modified kinematically aligned (mKA) and mechanically aligned (MA) total knee arthroplasty (TKA). A total of 90 knees treated with mKA-TKA and 63 knees treated with MA-TKA were classified based on CPAK. After adjusting for confounding factors, intraoperative soft tissue balance, including varus/valgus balance and joint component gap, range of motion (ROM), and the 2011 Knee Society score (KSS), were compared 1 year postoperatively using one-way ANOVA. The analysis included 69 knees classified as type I and 18 type II in the mKA group, and 52 type I and 11 type II in the MA group. Varus balance at 30 and 60 degrees flexion was significantly larger in mKA type I and MA type I compared to mKA type II (p < 0.001, 0.005, <0.001, 0.008). At 90 degrees, mKA type I showed a larger varus balance than both MA type I and mKA type II (p = 0.008, 0.002), while at 120 degrees, mKA type I demonstrated a larger varus balance than MA type I (p < 0.001). The improved ROM in mKA type I was greater than in MA type I (p = 0.04). Improvement in the objective indicator of the 2011 KSS was better in mKA type I than in mKA type II, and patient satisfaction was significantly better in mKA type I compared to both mKA type II and MA type I (p = 0.01, <0.001, 0.03). mKA type I preserved lateral laxity in mid- and deep flexion compared to both mKA type II and MA type I, potentially contributing to improved ROM and clinical outcomes.

Do knee alignment patterns differ between Middle Eastern and East Asian populations? A propensity-matched analysis using artificial intelligence

INTRODUCTION

Population-based differences in knee alignment patterns may impact osteoarthritis (OA) progression. This study compares lower extremity alignment in knee OA between Middle Eastern (UAE) and East Asian (South Korean) populations using artificial intelligence (AI)-assisted analysis.

METHODS

A retrospective review included patients with knee symptoms from South Korea (2009-2019) and the United Arab Emirates (UAE) (2015-2024). Exclusion criteria comprised prior knee surgeries, significant bony attrition, and low-quality radiographs. Propensity score matching controlled for age and sex differences between populations. Alignment parameters (hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and joint line convergence angle (JLCA)) and OA severity (Kellgren-Lawrence (KL) grade) were measured using artificial intelligence (AI) software, along with the analysis of coronal plane alignment of the knee (CPAK) classification. Subanalyses by sex and age group (under 40, 40-60, and over 60 years) were also conducted.

RESULTS

A total of 1098 UAE and 7138 South Korean patients (2196 and 14,276 knees, respectively) were evaluated in this study. Post-matching (1:2), body mass index was significantly higher in UAE patients (p < 0.001). CPAK type 1 was predominant in UAE male patients (42.4%), whereas type 2 was more common in South Korean male patients (30.6%). Female patients in both populations predominantly exhibited CPAK type 2 (UAE 30.6%; South Korea 35.3%). UAE patients showed a lower MPTA with increasing age, indicating a trend toward more varus alignment in older individuals.

CONCLUSIONS

A propensity score-matched analysis revealed significant alignment differences between Middle Eastern and East Asian populations, underscoring the importance of population-specific considerations in OA management.

Effect of joint-line obliquity on long-term survivorship of total knee arthroplasty: A postoperative phenotype analysis

PURPOSE

Whether the longevity of total knee arthroplasty (TKA) differs between postoperative phenotypes has not been investigated. This study aims to examine which phenotype has a worse long-term survival rate than the reference phenotype (neutral alignment-parallel joint line), and whether joint-line obliquity (JLO) affects the survivorship of TKA.

METHODS

A total of 945 knees that underwent primary TKAs for primary osteoarthritis from January 2000 to January 2009 were included. These were classified into nine postoperative phenotypes based on the combined assessment of the hip-knee-ankle (HKA) angle and JLO, measured on standing radiographs. The 5-, 10- and 15-year survival rates were analysed using Kaplan-Meier methods and log-rank tests. The long-term survival rates of each phenotype were compared with the reference phenotype.

RESULTS

There were 55 aseptic mechanical failures within a period of 10.4 ± 5.0 years. The most frequently observed phenotypes were the reference phenotype (n = 527), neutral alignment-lateral joint-line inclination (n = 162), varus alignment-lateral joint-line inclination (n = 104) and varus alignment-parallel joint line (n = 101). The overall failure rate for each phenotype was 3.6%, 3.7%, 18.3% and 7.9%, respectively. Only the 10- and 15-year survival rates of the varus alignment-lateral joint-line inclination phenotype were significantly different from those of the reference phenotype (97%-93% vs. 90%-69%; p = 0.017, <0.001).

CONCLUSION

The lateral joint-line inclination phenotype had an inferior long-term survival rate after varus-aligned TKA. This suggested that alignment and JLO affected the long-term survival rate of patients who underwent TKA.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Predictors of health-related quality of life after total knee arthroplasty: a case-control study

Total knee arthroplasty (TKA) improves patients' Health-related quality of life (HRQoL) compared to before surgery. However, based on our knowledge, the improvement in HRQoL after TKA, which depends on various factors, has yet to be investigated compared to healthy people. This study aimed to evaluate the HRQoL of patients compared to healthy people and the factors affecting the HRQoL after TKA. In this matched case-control study (1002 participants), HRQoL in 501 patients who underwent TKA between 2015 and 2022 at Shafa Yahyainan Hospital affiliated with Iran University of Medical Sciences were compared with 501 healthy controls. HRQoL was evaluated in two parts (before compared to 12 months after TKA and 12 months after TKA compared to the healthy population). The 36-item short-form health survey (SF-36) was used to evaluate HRQoL 12 months after surgery. The influencing factors on HRQoL were evaluated by multivariate logistic regression analysis. No significant difference was observed in the demographic characteristics of the participants in the two groups. The mean overall SF-36 score, 12 months after surgery, significantly improved compared to before surgery (64.21 ± 22.2 vs. 37.55 ± 15.13, p:0.001). The mean total score of SF-36 was statistically similar between the case and control groups (64.21 ± 22.2 VS 72.53 ± 25.3). The multivariate analysis showed that sex, BMI, number of comorbidities, postoperative compliance, and complications were significantly related to the decrease in patients' HRQoL (P < 0.001).TKA can improve the HRQoL except for two subscales of happiness/vitality and physical performance, similar to the healthy population. Female gender, obesity and overweight, comorbidity, bilateral TKA, non-adherence to postoperative physiotherapy, and complications were associated with decreased HRQoL.

Preoperative phenotype has no significant impact on the clinical outcomes and long-term survival of mechanically aligned total knee arthroplasty in Asian patients with osteoarthritis

Aims

The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral.

Methods

The study involved 945 TKAs, which were performed in 641 patients with primary OA, between January 2000 and January 2009. These were classified into 12 phenotypes based on the combined assessment of four categories of the arithmetic hip-knee-ankle angle and three categories of actual joint line obliquity. The rates of survival were analyzed using Kaplan-Meier methods and the log-rank test. The Hospital for Special Surgery score and survival of each phenotype were compared with those of the reference phenotype with neutral alignment and a parallel joint line. We also compared long-term survival between the unchanged phenotype group and the corrected to neutral alignment-parallel joint line group in patients with Type IV-b (mild to moderate varus alignment-parallel joint line) phenotype.

Results

The most common phenotype was Type I-b (mild to moderate varus alignment-medial joint line; 27.1% (n = 256)), followed by Type IV-b (23.2%; n = 219). There was no significant difference in the clinical outcomes and long-term survival between the groups. In Type IV-b phenotypes, the neutrally corrected group showed higher 15-year survival compared with the unchanged-phenotype group (94.9% (95% confidence interval (CI) 92.0 to 97.8) vs 74.2% (95% CI 98.0 to 100); p = 0.020).

Conclusion

Constitutional varus was confirmed in more than half of these patients. Mechanically aligned TKA can achieve consistent clinical outcomes and long-term survival, regardless of the patient's phenotype. The neutrally corrected group had better long-term survival compared with the unchanged phenotype group.

When to Do Selective Patellar Resurfacing in Total Knee Arthroplasty: A Decision-Making Algorithm Based on Pre-operative and Intra-operative Findings

Background

Persistent anterior knee pain post total knee arthroplasty (TKA) is a significant cause of patient dissatisfaction. Selective patellar resurfacing is commonly practiced for primary total knee replacement (TKR) but there is a paucity in literature regarding its decision making.

Study Objective

This study aims to develop a decision-making algorithm for selective patellar resurfacing using Hospital for Special Surgery Patello-femoral Assessment score (HSS PFA score), weight-bearing patellofemoral X-ray, and intraoperative cartilage wear assessment based on the Outerbridge classification.

Materials and Methods

This prospective study enrolled 65 patients, assessing preoperative factors including HSS PFA score and Baldini view radiography. Intraoperative cartilage wear was categorized using the Outerbridge classification. Preoperative findings were correlated with intraoperative outcomes through statistical analysis, leading to the development of a predictive algorithm. The efficiency of algorithm was assessed at 3-year follow-up using HSS PFA score.

Results

A significant negative correlation (r = - 0.272, p = 0.029) was observed between HSS PFA score and cartilage wear. However, no significant relationships were established between HSS PFA score and Baldini view observations, including radiological tilt (p = 0.517) and displacement (p = 0.277). Intraoperative cartilage wear versus patellar tilt (p = 0.65) and displacement (p = 0.837) also yielded non-significant results. Three-year follow-up examinations revealed no complications and significant HSS PFA score improvements in all patients.

Conclusion

The requirement for patellar resurfacing can be predicted using a combination of preoperative parameter such as HSS PFA score and the intra-operative cartilage wear. We put forward an algorithm based on above findings to aid in the decision making.

Early- to Mid-Term Review of a Prospective, Multi-Center, International, Outcomes Study of an Anatomically Designed Implant with Posterior-Stabilized Bearing in Total Knee Arthroplasty

Background and Objectives: National joint registries report higher total knee arthroplasty (TKA) revision rates in posterior-stabilized (PS) systems compared to non-posterior-stabilized designs. The purpose of this study was to investigate the implant survivorship and clinical outcomes of an anatomic implant with a PS bearing. Materials and Methods: An early- to mid-term follow-up of a prospective, multi-center, non-controlled outcomes study of patients who received primary TKA between November 2014 and June 2017 was performed. A total of 800 cases using PS bearings that were implanted in 664 patients were monitored post-operatively for their implant survivorship and adverse events for up to five years. The Knee Society Knee and Function scores, patient satisfaction, the five-dimensional European Quality of Life questionnaire, and range of motion (ROM) were evaluated pre-operatively and post-operatively at six weeks, six months, one year, two years, three years, and five years. Results: The mean follow-up period was 3.7 ± 1.3 years, and the three-year implant survival rate was 99.3% (95% CI: 98.4%, 99.7%) with five revisions during the five-year follow-up. Patient satisfaction was 96.1% at six weeks and increased to 99.3% at one year. All patient-reported outcome measures significantly (p < 0.0001) increased up to the one-year follow-up and then remained stable up to the five-year follow-up. Conclusions: This study supports the excellent survivorship and patient-reported outcomes of the Persona® Knee system using cemented, fixed bearing, posterior-stabilized components with minimal complications at early- to mid-term follow-up in an international Asian population. Ongoing observations are being performed to investigate the mid- to long-term survivorship and clinical outcomes associated with this knee system.

Comparable outcomes of reverse shoulder arthroplasty for proximal humerus fractures and for rotator cuff arthropathy in a predominantly asian population

Background

Reverse shoulder arthroplasty (RSA) was initially developed for rotator cuff arthropathy but has been expanded to treat comminuted proximal humerus fractures. Few studies have compared RSA for traumatic and degenerative indications. We present the first report of mid-term outcomes of RSA comparing both indications in an Asian population.

Methods

113 degenerative and 20 fracture patients underwent RSA from 2010 to 2019. Patients with degenerative indications were 4:1 propensity-score matched to fractures and adjusted for age and sex. Patients were assessed for range of motion (ROM), strength, pain, Constant-Murley score (CMS), University of California Los Angeles Shoulder Score (UCLA) and Oxford shoulder score (OSS) preoperatively, at 6-months and 1-year. Patients' satisfaction, expectation fulfilment and minimal clinically important difference (MCID) were analysed.

Results

Degenerative patients had better ROM, isometric strength and CMS at 6-months, although at 1-year only abduction was superior (104.8  ±  17.3° vs 86.7  ±  19.8°). No significant differences in pain, UCLA and OSS were observed. Most improvements occurred within 6 months. Similar proportions of patients were satisfied (83.3% vs 73.3%, p = 0.460) and attained MCID (85.0% vs 86.7%, p = 1.000) at 1-year.

Discussion

Although initially exhibiting slower recovery, patients with proximal humerus fractures can expect similar functional recovery and satisfaction at 1-year compared to those who received RSA for degenerative indications.

Geographic Variation in Knee Phenotypes Based on the Coronal Plane Alignment of the Knee Classification: A Systematic Review

BACKGROUND

The extent of geographic variation in knee phenotypes remains unclear. The Coronal Plane Alignment of the Knee (CPAK) Classification proposes 9 coronal plane phenotypes based on constitutional limb alignment and joint line obliquity. This systematic review aims to examine differences in the distributions of CPAK types across geographic regions.

METHODS

A systematic review of the literature was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies reporting distributions of knee phenotypes according to the CPAK classification for healthy and/or arthritic knees were included.

RESULTS

There were 7 studies included, accounting for 5,964 knees in 3,917 subjects. Among healthy knees (n = 1,214), CPAK type II was the most common type in Belgium (39.2%), Taiwan (39.3%), and India (25.6%). Among arthritic knees (n = 2,804), CPAK type I was the most common in France (33.4%), India (58.8%), and Japan (53.8%), whereas CPAK type II was the most common in Australia (32.8%). The proportion of CPAK type I and II knees varied significantly across geographic regions among healthy (P < .01) and arthritic knees (P < .01).

CONCLUSION

Significant variation in CPAK distributions exists between countries. Further work is needed to delineate racial and sexual differences in CPAK types, which were not explored in this article. A better understanding of population-level variability in knee phenotypes may enable orthopaedic surgeons to offer a more personalized approach to knee arthroplasty.

Neutral Mechanical Alignment and Prevalence of Constitutional Varus Knees Among the Saudi Population at King Saud University Medical City

Background Various studies have described the restoration of the neutral mechanical alignment of the lower limb in total knee replacement (TKR) as a key factor of knee implant durability. Mechanical alignment of the knee requires that the tibial and femoral cuts are perpendicular to the mechanical axis of each bone in the coronal plane. Objectives The aim of this study is to investigate mechanical knee alignment and the prevalence of constitutional varus knee among the Saudi population at a single tertiary center with no history of musculoskeletal abnormalities. Methodology This is a retrospective cross-sectional study involving patients with no musculoskeletal abnormality who had their lower limb X-ray Centigram using the universal viewer zero footprint system made between 2015 and 2021. The study took place at King Saud University Medical City. The X-rays were obtained from patients' electronic medical records retrospectively. A total of 728 knees of 370 males and 358 females were included in this study. Results The results showed that 165 male knees (44.4%) and 218 female knees (60%) had constitutional varus alignment with the hip-knee-ankle (HKA) angle of ≤3° or less. The average HKA angle was smaller in males than in females: -3.69° versus -1.98°, respectively. Conclusion We have identified variables and factors that can help surgeons detect the constitutional varus on a full leg radiograph preoperatively at the time of TKA, regardless of the osteoarthritic changes of the knee. We encourage the scientific community to look for causes and risk factors for developing constitutional varus.

Fixed 6° distal femoral cut consistently achieves neutral alignment for Asians, Caucasians, and Native Hawaiian/Pacific Islanders

BACKGROUND

Restoration of a neutral mechanical axis (MA) is important to the success of total knee arthroplasty (TKA). While known differences are present between Asians and Caucasians regarding native knee alignment, it is unknown whether such differences exist amongst Native Hawaiian/Other Pacific Islanders (NHPI) or if utilizing a fixed distal femoral cut of 6° can consistently achieve a neutral MA in these minority racial groups. This study examines the preoperative deformities presented by Asians, Caucasians, and NHPI, and the resulting knee alignment achieved following TKA when a fixed 6° distal femoral cut is targeted for all patients.

METHODS

Preoperative and postoperative MA was measured from 835 Asian, 447 Caucasian, and 163 NHPI hip-to-ankle radiographs. All patients underwent TKA in which a standard distal femoral cut of 6° valgus was targeted for all patients. Data were evaluated as continuous variables and by groupings of varus (MA < - 3°), valgus (MA > 3°), and neutral (- 3° ≤ MA ≤ 3°) alignment.

RESULTS

Preoperative deformity ranged from 38° varus to 29° valgus. The proportion of Asian and NHPI presenting with varus alignment prior to surgery was significantly greater than Caucasian patients in both males (Asians: 80.6%; Caucasians: 67.0%; NHPI: 79.0%, p = 0.001) and females (Asians: 66.1%; Caucasians: 45.7%; NHPI: 63.2%, p < 0.001). There was no difference in the proportion of patients (72-79%) achieving a neutral MA amongst all three racial groups.

CONCLUSION

NHPI appear to have similar preoperative deformities to Asians with both groups having significantly more varus alignment than Caucasians. Despite a wide range of preoperative deformity, application of a fixed distal femoral cut of 6° valgus successfully established a neutral MA equally in the majority of patients across all three racial groups.

Anatomical bone structure differences in patients with hemophilic arthropathy of the knee

Objectives:

The anatomical differences of the bony structure of the knee joint in patients with hemophilia were evaluated, and the results were compared with the knees of patients with primary gonarthrosis and no arthrosis.

Material and Methods:

This study reviewed 41 knees in 21 patients (with an Arnold-Hilgartner classification of Stages 4 and 5 hemophilic arthropathy) who underwent total knee arthroplasty in single center. Two control groups including 21 asymptomatic patients (42 knees) and 21 primary knee osteoarthritis patients (42 knees) were formed to compare the measurements with hemophiliacs. Femoral mediolateral width, femoral anteroposterior width, femur and tibia diaphysis width, adductor tubercle-joint line distance, tibial plateau width, and medial and lateral tibia plateau width were measured separately.

Results:

Femoral mediolateral width was significantly narrow comparing with healthy individuals and primary knee osteoarthritis group. Tibial plateau was similar to asymptomatic group but significantly narrow compared with primary knee osteoarthritis group. With the correlation, the tibial plateau measurements and medial and lateral plateau were significantly narrow at hemophilic arthropathy group (P < 0.05). The slope was less in hemophilic patients as compared with asymptomatic individuals (P: 0.001). Hemophilic patients had larger femoral aspect ratios than asymptomatic group but there were no observable differences with the primary osteoarthritis group. For the tibial aspect ratios, hemophilic had a smaller ratio than the primary osteoarthritis group but there were no significant differences with the asymptomatic group.

Conclusion:

Hemophilic knee has a mismatch between femoral and tibial side while comparing with the other groups.

Level of Evidence:

Level IV, cross-sectional study.

Effect of joint immobilization using extension splint immediately after total knee arthroplasty on post-operative knee function and pain: a randomized clinical trial

PURPOSE

Investigate the effect of semirigid extension bracing after total knee arthroplasty (TKA) on articular pain and function.

METHODS

The present randomized clinical trial included 72 patients undergoing unilateral primary TKA. Patients in the case group received eight days of post-operative semirigid extension-locked knee bracing, whereas controls did not. The outcomes assessed preoperatively and on the first, ninth, 30th day, and one year post-operatively included the knee society score (KSS), functional KSS (FKSS), VAS pain score, amount of postoperative opiate painkiller usage (tablet oxycodone 5mg), and knee ROM.

RESULTS

The case group had a significantly lower flexion ROM on postoperative day nine compared to the control group (95.3° vs. 100.8°, p=0.03), while it became significantly higher 1 month (114.1° vs. 104.7°, p=0.03) and one year post-operative (128.0° vs. 120.5°, p=0.002). Also, FKSS was significantly higher in the case group than in the controls in the one month post-operative assessment (37.0 vs. 32.6, p=0.009) but not in the one year post-operative assessment. The case group patients had a significantly lower pain than the controls on days one (5.8 vs. 7.2, p=0.02) and nine post-operative (4.1 vs. 5.2, p=0.048), but not at later assessments. The amount of one month post-operative opium (oxycodone) consumption was significantly lower in the brace group (12.4 vs. 14.1 tablets, p=0.03). The KSS were not significantly different between the groups after the surgery.

CONCLUSION

Extension-locked splinting immediately after TKA is a noninvasive, non-pharmacological, and inexpensive intervention with possible promising effects on knee ROM, short-term functional improvement, and acute post-operative pain management.

Kinematic alignment versus mechanical alignment in primary total knee arthroplasty: an updated meta-analysis of randomized controlled trials

Background

The purpose of this study was to perform an updated meta-analysis to compare the outcomes of kinematic alignment (KA) and mechanical alignment (MA) in patients undergoing total knee arthroplasty.

Methods

PubMed, EMBASE, Web of Science, Google Scholar, and the Cochrane Library were systematically searched. Eligible randomized controlled trials regarding the clinical outcomes of patients undergoing total knee arthroplasty with KA and MA were included for the analysis.

Results

A total of 1112 participants were included in this study, including 559 participants with KA and 553 patients with MA. This study revealed that the Western Ontario and McMaster Universities Osteoarthritis Index, Knee Society Score (knee and combined), and knee flexion range were better in the patients with kinematic alignment than in the mechanical alignment. In terms of radiological results, the femoral knee angle, mechanical medial proximal tibial angle, and joint line orientation angle were significantly different between the two techniques. Perioperatively, the walk distance before discharge was longer in the KA group than in the MA group. In contrast, other functional outcomes, radiological results, perioperative outcomes, and postoperative complication rates were similar in both the kinematic and mechanical alignment groups.

Conclusions

The KA technique achieved better functional outcomes than the mechanical technique in terms of KSS (knee and combined), WOMAC scores, and knee flexion range.

PROSPERO trial registration number CRD42021264519. Date registration: July 28, 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03097-2.

Various Types of Medial Tibial Bone Resorption after Total Knee Arthroplasty Using a Thick Cobalt Chromium Tibial Baseplate

Recent literature has implicated a thick cobalt chromium baseplate as a potential source of stress shielding and medial tibial bone resorption after total knee arthroplasty (TKA) in a Western population. The purpose was to calculate the incidence of various types and severity of medial tibial bone resorption utilizing a novel classification system after TKA with a thick cobalt chromium baseplate in Asian patients. Five hundred TKAs using Attune prostheses with mean follow-up of 3.4 years were evaluated, using the prospective radiographic data. The mean age was 71.3 years. The preoperative mechanical axis was varus, 11.2 degrees. The type and severity of medial tibial bone resorption were categorized as type U (resorption under the tibial baseplate up to 50% [U1] or beyond 50% [U2] of medial tibial tray width), C (resorption around the penetrated cement under the baseplate), and M (resorption on the medial tibial cortex without extension to the baseplate). Bone resorption of medial proximal tibia was observed in 96 knees (19.2%). Types U1 and U2 were seen in 46 and 28 knees, respectively. Type C was observed in 12 knees and type M in 10 knees. The type U resorption group had significantly more preoperative varus deformity (varus 12.9 vs. 10.9 degrees, p = 0.017). Medial tibial bone resorption after TKAs using a thick cobalt chromium baseplate is not uncommon and has various locations, types, and severities. The medial tibial bone resorption might be related to various causes, including stress shielding, thermal necrosis from cement in the bony hole, and bony devascularization. The type-U resorption has to be closely observed in patients with preoperative severe varus deformity. This is a Level IV study.

Influence of increased pain sensitivity on patient-reported outcomes following total knee arthroplasty

PURPOSE

The purpose of this study was to discover whether increased pain sensitivity was associated with postoperative pain and patient-reported outcome measures (PROMs) after total knee arthroplasty (TKA).

METHODS

Pain sensitivity was evaluated preoperatively using a pain sensitivity questionnaire (PSQ). Resting, walking, nighttime, and average pain visual analog scale (VAS) were measured before surgery and 6 weeks, 3 months, 6 months, and 1 year after surgery. PROMs were also evaluated based on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and patient satisfaction. The association between pain VAS average score, WOMAC total score, and PSQ score (minor, moderate, and total score) was assessed at each stage.

RESULTS

There were 59 patients with a high PSQ score (≥ 5.2) and 53 with a low PSQ score (< 5.2). Up to 1 year postoperatively, the group with high PSQ scores had higher resting, walking, nighttime, and average pain VAS scores than the group with low scores (all p < 0.05). Worse preoperative WOMAC pain, function, and total scores continued until 1 year after surgery in the high-scoring PSQ group (all p < 0.05). The group with low PSQ scores was more satisfied with surgery than the group with high scores (p = 0.027). There was a positive correlation between preoperative PSQ score and pain VAS average score at all time points (all p < 0.05). A relationship between PSQ score and WOMAC total score was also observed (all p < 0.05).

CONCLUSION

Increased pain sensitivity is a factor related to higher postoperative pain levels and inferior PROMs in patients undergoing primary TKA.

LEVEL OF EVIDENCE

Case-controlled study, III.

Distribution of Coronal Plane Alignment of the Knee Classification in Patients with Knee Osteoarthritis in Japan

Coronal plane alignment of the knee (CPAK) has recently been proposed as a simple and universal classification system to determine the suitability of a particular phenotype of the knee to a specific alignment strategy for knee replacement surgery. Although racial differences may affect knee alignment, there are no reports on the racial distribution of this classification system. We aimed to clarify the distribution of CPAK classification in patients with osteoarthritis who underwent total knee arthroplasty (TKA) in Japan. Consecutive patients who underwent primary TKA were analyzed retrospectively. The knees were categorized according to the CPAK classification system which comprised of two independent variables (arithmetic hip-knee-ankle [aHKA] angle and joint-line obliquity [JLO]) with three respective subgroups to create the following nine phenotypes of the knee: type I (varus aHKA and apex distal JLO), type II (neutral aHKA and apex distal JLO), type III (valgus aHKA and apex distal JLO), type IV (varus aHKA and neutral JLO), type V (neutral aHKA and neutral JLO), and type VI (valgus aHKA and neutral JLO), type VII (varus aHKA and apex proximal), type VIII (neutral aHKA and apex proximal), and type IX (valgus aHKA and apex proximal). The distribution of the phenotypes in the Japanese population was investigated as a primary outcome. To accurately compare the results with previous studies conducted on non-Japanese patients, a sex-matched distribution was investigated as a secondary outcome. A total of 570 knees were investigated of which 500 knees were examined after exclusions. The most common distribution was type I (53.8%), followed by type II (25.4%), type III (8.2%), type IV (7.2%), type V (4.4%), and type VI (1.0%). Types VII, VIII, and IX were not distributed. The sex-matched distribution was nearly identical to the overall distribution in Japan. The majority of patients with knee osteoarthritis in Japan had medially tilted joints with constitutional varus alignment.

Efficacy of duloxetine compared with opioid for postoperative pain control following total knee arthroplasty

Background

The purpose of this study was to assess the efficacy of duloxetine as an alternative to opioid treatment for postoperative pain management following total knee arthroplasty (TKA).

Methods

Among 944 patients, 290 (30.7%) of patients received opioid or duloxetine for pain control for 6 weeks when the pain Visual Analogue Scale (VAS) score was greater than 4 out of 10 at the time of discharge. 121 patients in the Opioid group and 118 in the Duloxetine group were followed up for more than one year. Preoperative and postoperative patient reported outcome measures (pain VAS score, Western Ontario and McMaster Universities OA Index (WOMAC) score were compared. The rate of further drug prescription (opioid or duloxetine) after 6 weeks of first prescription, 30-day readmission rate, and side effects were also investigated.

Results

There was no significant difference in pain VAS score, WOMAC Pain and Function score, at each time point between before and after surgery (all p>0.05). Fifteen (9.8%) patients in the opioid group and six (4.4%) patients in the duloxetine group were prescribed additional medication after first 6 weeks, showing no significant (p>0.05) difference in proportion. The 30-day readmission rate and the incidence of side effects were also similar (all p>0.05). There was no difference in the incidence of side effects between the two groups (p>0.05).

Conclusion

Duloxetine and opioid did not show any difference in pain control, function, and side effects for up to one year after TKA. Although large-scale randomized controlled trials are still required to further confirm the side effects of duloxetine, it can be considered as an alternative to opioid for postoperative pain control following TKA.

Anatomical tibial component is related to more medial tibial stress shielding after total knee arthroplasty in Korean patients

PURPOSE

This study aimed to investigate stress shielding of anatomical tibial components (ATCs) in comparison to conventional symmetric tibial components (STCs) in Korean patients which may be related to medial tibial bone loss.

METHOD

78 knees in 59 patients with ATCs (Persona™) and 74 knees in 58 patients with STCs (NexGen LPS-Flex™) were retrospectively reviewed. Radiographic parameters and clinical outcomes in both groups were compared. Logistic regression analysis was performed to identify risk factors for medial tibial bone loss.

RESULTS

Medial tibial bone loss was significantly greater in the ATC group (1.6 ± 1.3 mm) than in the STC group (0.4 ± 0.8 mm) (p < 0.001). The ATC group showed a shorter distance between the distal metal tip and anteromedial cortex and higher invading into the sclerotic bone lesion (ISBL) than the STC group (p = 0.034 and p = 0.044, respectively). Multiple logistic regression analysis suggested ATC, a shorter distance to the anteromedial cortex, and the presence of ISBL as risk factors for medial tibial bone loss. The odds ratios of medial tibial bone loss according to type of prosthesis, distance to anteromedial cortex, and presence of ISBL were 6.25 (range 2.86-13.63, p < 0.001), 0.69 (range 0.51-0.93, p = 0.015), and 3.79 (range 1.56-9.21, p = 0.003), respectively. Notwithstanding, there was no difference in clinical outcomes between the two groups.

CONCLUSION

In Korean patients, ATCs potentially causes greater medial tibial bone loss due to stress shielding than STCs. The design, however, does not yet appear to affect clinical outcomes at mid-term follow-up.

LEVEL OF EVIDENCE

Retrospective cohort study, level III.

Why do knees after total knee arthroplasty fail in different parts of the world?

OBJECTIVE

The aim of this narrative review was to provide an overview of failure modes after total knee arthroplasty in different parts of the world based on data from worldwide representative studies and National Joint Registries.

METHODS

A review of the available literature was performed using the keyword terms "total knee arthroplasty", "revision", "failure", "reasons", "causes", "complications", "epidemiology", "etiology"; "assessment", "painful knee", "registry" and "national" in several combinations. The following databases were assessed: Pubmed (https://pubmed.ncbi.nlm.nih.gov), Cochrane Reviews (https://www.cochrane.org), Google Scholar (https://scholar.google.com). In addition, registry data were obtained directly from national registry archives. Due to the heterogeneity of available data it was decided to present the review in a narrative manner.

RESULTS

Current literature report that infection has become the primary acute cause of TKA failure, while aseptic loosening and instability remain the overall most frequent reasons for revisions. Based on national registries certain tendencies can be deducted. The predominant overall failure mode of aseptic loosening is particularly found in Japan, United Kingdom, New Zealand and Switzerland. Leading early TKA failure mode represents infection with percentages of 20-30% in Sweden, Australia, New Zealand, Japan and the United States. Higher numbers could only be found in clinical studies on the Asian continent such as Korea (38%), China (53%), Iran (44%) and India (87%).

CONCLUSION

Although there are regional differences in TKA failure modes, TKA fails worldwide especially due to infections and aseptic loosening. It is important to diagnose these in good time and reliably using appropriate, standardized diagnostics in order to recommend the best possible therapy to the patient.

Cross-cultural adaptation and validation of the Korean version of the Central Sensitization Inventory in patients undergoing total knee arthroplasty for knee osteoarthritis

The purpose of this study was to establish a Korean version of the Central Sensitization Inventory (CSI-K) for Korean-speaking patients facing total knee arthroplasty (TKA) for knee osteoarthritis (OA) and to investigate the psychometric characteristics of the CSI-K. We recruited a total of 269 patients with knee OA who were scheduled to undergo TKA for the study. CSI-K and pain-related outcomes, including the pain visual analog scale (VAS) and the Western Ontario and McMaster Universities OA Index (WOMAC) pain sub-scores, were measured. Since central sensitization (CS) is closely related to the quality of life (QOL) and limited functionality as well as pain, the patient's function was measured using the WOMAC function sub-scores, and QOL was measured using the EuroQol five-dimension test (EQ-5D). Reliability and validity were evaluated. Exploratory factor analysis (EFA) was conducted to begin the data reduction to validate the existing questionnaire translation. The internal consistency was excellent, with a Cronbach's alpha of 0.941. The test-retest reliability was acceptable-to-excellent with an ICC of 0.888. As expected, the CSI scores correlated strongly with the WOMAC pain scores (r = 0.524, p < 0.001) and moderately with the pain VAS (r = 0.496, p < 0.001), the WOMAC function (r = 0.408, p < 0.001), and the EQ-5D scores (r = 0.437, p < 0.001). EFA resulted in a six-factor model. The findings demonstrate that the CSI was successfully trans-culturally adapted into a simplified Korean version (CSI-K) that was reliable and valid for Korean-speaking patients who awaiting TKA for knee OA.

Western-designed total knee implants mismatch Saudi patient knees. Anatomical bony measurements documented by computed tomography

Objectives:

To determine the anthropometric features of Saudi knees compared with knees of other ethnicities and reveal mismatches among different knee implant systems.

Methods:

All knee computed tomography images obtained between January 2016 and September 2016 for varying medical reasons in a tertiary care hospital in Southwestern Saudi Arabia were retrospectively evaluated. Patients aged <18 years, with trauma or soft tissue or bone tumors were excluded. Eleven parameters were measured for each knee joint.

Results:

We evaluated 100 knees of 50 Saudi patients (25 men, 25 women) aged 28-85 (mean, 57.3) years. No statistically significant differences were found in age and Sasaki angle measurements between male and female patients. All other parameters were significantly larger in male than female knees. Our measurements were close to those published for Chinese, Thai, and Korean patients; however, published measurements were larger for Caucasian and Indian knees than our measurements.

Conclusion:

The Saudi population has morphological features of knee bone anatomy that do not match with the widely available prostheses designed for Caucasian knees. As several studies of different ethnicities have documented considerable prosthesis mismatch; our study further indicates the need for new implant designs that take these variations into account.

Current state of total knee arthroplasty

Total knee arthroplasty (TKA) is a successful and cost-effective treatment for end-stage degenerative arthritis. The aging of society and an increase in the prevalence of obesity has led to increases in the prevalence of arthritis and the incidence of TKA. Currently, the total number of procedures in Korea per year has reached 90,000. With the rapid growth, we need to know about the current state of TKA. The purpose of this review is to summarize the recent literature regarding TKA. The main indication for TKA is end-stage arthritis with severe pain, reduced function, and no response to conservative management. Metal on the polyethylene-bearing surface and cobalt alloy are used in most TKAs. Despite good clinical outcomes and long-term survival rates after TKA in many papers, 20% of patients are dissatisfied with the outcome of surgery. To improve the patient’s satisfaction, surgeons should understand factors affecting patient’s satisfaction, including patient’s expectations, age, and preoperative mental state. Navigation-assisted surgery and robotic surgery have been introduced in knee arthroplasty to achieve more precise and accurate alignment. There is some evidence to suggest that computer-assisted surgery reduces revision rates. However, clinical efficacy is also controversial, and a long-term follow-up study is required. The common complications of TKA include infection, polyethylene wear, loosening, stiffness, periprosthetic fracture, and thromboembolism. An understanding of the potential complications and pitfalls of TKA is essential for prevention.

Underestimation and undertreatment of osteoporosis in patients awaiting primary total knee arthroplasty

INTRODUCTION

Osteoporosis is generally regarded as a risk factor for periprosthetic fracture during or after primary total knee arthroplasty (TKA). Despite this, little is known about osteoporosis in patients undergoing elective primary TKA Therefore, we sought to investigate the prevalence of osteoporosis and rates of pharmacologic osteoporosis treatment prior to primary TKA. We hypothesized that preoperative osteoporosis is underestimated and undertreated in the primary TKA population.

MATERIALS AND METHODS

This retrospective study included consecutive 1972 patients scheduled for elective primary TKA at a single tertiary hospital (age, 50-89 years). Charts were reviewed for patient demographics, prior pharmacologic osteoporosis treatment and Knee Society (KS) scoring system and WOMAC score. Dual energy X-ray absorptiometry (DEXA) measurement of the lumbar vertebrae and proximal femur was performed in all patients on the day before surgery. The associations of BMD with age, sex, body mass index (BMI), and clinical outcome were analyzed.

RESULTS

The prevalence of osteoporosis was 50.0% (53.4% in women and 7.0% in men). Among patients with osteoporosis, only 15.1% (149/986) of patients (15.0% in women and 30.0% in men) had pharmacological osteoporosis treatment prior to primary TKA. Age, sex and WOMAC stiffness showed association with osteoporosis. Sex (odds ratio (OR): 20.83, p < 0.001) was the most significant factor associated with osteoporosis.

CONCLUSION

Osteoporosis was highly prevalent in patients awaiting TKA, but the rates of diagnosis and pharmacologic osteoporosis treatment were low. Therefore, more attention needs to estimate and treat osteoporosis in patients awaiting primary TKA, especially in female patients.

Intraoperative Patella Dimension Measurement in Asian Female Patients and Its Relevance in Patellar Resurfacing in TKA

BACKGROUND

Implants used for total knee arthroplasty (TKA) in Asian patients are mostly produced based on anthropometry of the Western population, thus causing problem with patella sizing, especially in Asian females where the patellae are regarded to be smaller. This study is to define intraoperative patella dimensions in our female populations and compare them with current prosthetic systems available at our institution.

METHODS

This is a cross-sectional study involving 156 TKA female patients with normal patellae. The patella height, width, thickness, medial and lateral articular facets' width and thickness, and the dome position were measured. The smallest implant size from 3 manufacturers was compared to the data obtained. Analysis using descriptive statistics was used to get the mean and median of anatomical patella dimensions, whereas the independent T test and one-way ANOVA test were used to compare the Malaysian female's patella dimensions with various implant sizes.

RESULTS

The articular surface of the patella was found to have an oval shape with a width-height ratio of 1.31. The mean (SD) patella thickness, width, and height were 20.7 (1.85) mm, 40.7 (3.79) mm, and 31.3 (2.81) mm, respectively. Only 17.9% fit for smallest implant size from all 3 manufacturers. The oval-shape implant was suitable in 53.8% patients based on their width-height ratio. The dome position is 2.2 mm medial to centre.

CONCLUSION

These female patients have thinner and smaller patella, which are generally unable to accommodate patellar components based on the Caucasian database. Therefore, orthopaedic implant manufacturers should consider optimizing the thicknesses as well as widths of their patellar prostheses.

Short knee radiographs can be inadequate for estimating TKA alignment in knees with bowing

Purpose

The aim of this study was to compare the discrepancy of alignment categorization in total knee arthroplasty (TKA) between the anatomical femorotibial angle (aFTA) measured on short knee radiographs and the mechanical hip–knee–ankle axis angle (mHKA) measured on full-length radiographs in knees with and without bowing.

Methods

From January 2014 to June 2017, 107 of 526 osteoarthritic knees at our hospital were found to have femoral or tibial bowing. Bowing was defined as a femoral bowing angle (FBA) > 3° or < − 3° or a tibial bowing angle (TBA) > 2° or < − 2° in full-length preoperative radiographs. Among 419 knees without bowing, we selected 107 knees as a control group using propensity-score matching. Postoperative alignments were categorized by aFTA in short knee radiographs and mHKA in full-length radiographs into neutral (2° ≤ aFTA≤7°, − 3° ≤ mHKA≤3°), varus (aFTA< 2°, mHKA<− 3°), and valgus (aFTA> 7°, mHKA> 3°) alignments. We compared the categorization of alignments between knees with and without bowing using the McNemar test and used logistic regression to find factors for the alignment discordance.

Results

Coronal alignment was discordant in 26.2% of the knees with bowing and 13.1% of the knees without bowing (p < 0.001). FBAs were a significant factor affecting the discordance of alignment categorization (OR = 1.152, 95%CI 1.038–1.279, p = 0.008).

Conclusion

Short knee radiographs are insufficient for estimating coronal alignment after TKA, particularly in knees with femoral bowing.

Level of evidence: III

Retrospective comparative study.

Central Sensitization Is a Risk Factor for Persistent Postoperative Pain and Dissatisfaction in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

The objective of this study is to investigate whether central sensitization (CS) was associated with patient dissatisfaction after revision total knee arthroplasty (TKA).

METHODS

Between 2012 and 2016, 68 cases (68 patients) of revision TKA performed by a single surgeon were included in this study with a minimum follow-up of 2 years. Patients were categorized into 2 groups by 40-point preoperative Central Sensitization Inventory (CSI) scores. The control group consisted of 48 patients (48 knees) with CSI scores of less than 40 points, while the CS group consisted of 20 patients (20 knees) with CSI scores of 40 points or more. Clinical outcomes were evaluated using an 11-point visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index scores. Patient satisfaction was evaluated using the satisfaction items of the new Knee Society Scores, where scores ≥20 indicated satisfaction.

RESULTS

Higher preoperative pain VAS scores in the CS group were maintained 3, 6, 12, and 24 months postoperatively (all P < .05). The CS group showed significantly worse pain, function subscores, and total scores of the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and at 2 years postoperatively. Forty-four (91.7%) patients in the control group and 3 (15.0%) patients in the CS group were satisfied with their revision TKAs (P < .001). Multivariate logistic regression analysis demonstrated that the odds of dissatisfaction after revision TKAs were increased 39.081 times (95% confidence interval 6.926-220.504, P < .001) in patients with CSI scores ≥40. Higher VAS intensity 2 years postoperatively also predicted dissatisfaction following revision TKA (odds ratio 1.864, 95% confidence interval 1.086-3.199, P = .024).

CONCLUSION

CS is a risk factor for persistent postoperative pain and dissatisfaction in patients undergoing revision TKAs.

LEVEL OF EVIDENCE

III.

Factors Affecting Tibial Tuberosity-Trochlear Groove Distance in Recurrent Patellar Dislocation

Background

The tibial tuberosity-trochlear groove (TT-TG) distance is used to determine the necessity of tibial tubercle osteotomy. We conducted this study to determine the extent to which each of the tibial tuberosity lateralization, trochlear groove medialization, and knee rotation angle affects the TT-TG distance in both normal and patella dislocated patients and thereby scrutinize the rationale for tuberosity transfer based on the TT-TG distance.

Methods

Retrospective analysis of rotational profile computed tomography was done for patella dislocated and control group patients. Femoral anteversion, tibial torsion, knee rotation angle, tuberosity lateralization, and trochlear groove medialization were assessed in all patients. Relationship of these parameters with the TT-TG distance was investigated to evaluate their effects on the TT-TG distance.

Results

We observed that the patellar dislocation group, compared to the control group, had increased TT-TG distance (mean, 19.05 mm vs. 9.02 mm) and greater tuberosity lateralization (mean, 64.1% vs. 60.7%) and tibial external rotation in relation to the femur (mean, 7.9° vs. -0.81°).

Conclusions

Tuberosity lateralization and knee rotation were factors affecting patellar dislocation. These factors should be considered in addition to the TT-TG distance to determine the need for tibial tubercle osteotomy in patients with patellar dislocation.

Does the Preoperative Varus Deformity Influence the Survival of Postoperative Neutral-Aligned TKAs? An Analysis With a Minimum 5-Year Follow-Up

BACKGROUND

Postoperative neutral alignment may be an important factor for longevity of total knee arthroplasty (TKA). In knees with severe varus deformity, greater soft tissue release and bone resection were required to achieve neutral alignment. We investigated the relationship between the severity of preoperative varus deformity and longevity of neutral-aligned TKAs.

METHODS

Of the 723 knees in patients who underwent primary TKA for varus-type osteoarthritis between November 1998 and June 2009, 496 knees aligned neutrally (the postoperative mechanical hip-knee-ankle [HKA] axis angle ranged between -3° and 3°) and followed up for at least 5 years were included in the study. The mean follow-up period was 9.28 years. Patients were divided into 4 groups based on their preoperative HKAs: mild (0° < HKA ≤ 5°, n = 79), moderate (5° < HKA ≤ 10°, n = 204), severe (10° < HKA ≤ 15°, n = 149), and very severe (HKA > 15°, n = 64) groups. Failure was defined as need for revisional TKA for mechanical reason. Survival was analyzed by Kaplan-Meier method and log-rank test.

RESULTS

The overall failure rate was 2.02% (10 of 496 prostheses). The cumulative survival rates of neutral-aligned TKAs at 10 years were 97.4% (95% confidence interval [CI], 93.9%-100%), 99.0% (95% CI, 97.6%-100%), 97.8% (95% CI, 95.4%-100%), and 96.9% (95% CI, 92.6%-100%) in mild, moderate, severe, and very severe varus groups, respectively. There were no significant differences between group survival rates (P = .395).

CONCLUSION

The severity of preoperative varus deformity did not affect survival rates of neutral-aligned TKAs over 10 years.

Anthropometric Measurements of Knee Joints in the Hispanic Population

BACKGROUND

Total knee arthroplasty (TKA) systems provide a set of incrementally sized tibial and femoral components intended to accommodate most knee parameters. However, the most commonly used systems in the United States were developed using data from Caucasian patients which might not lead to the best fit in non-Caucasians. Therefore, we wanted to evaluate whether these TKA systems proportionally match femoral and tibial measurements in Hispanics.

METHODS

All lower extremity magnetic resonance imaging performed at our institution between January 2007 and October 2015 were screened. A total of 500 nonarthritic knees from the same number of Hispanic patients were included in this retrospective descriptive radiographic study. Intraoperative osseous TKA resections were simulated on magnetic resonance imaging. Linear regression analyses were used to contrast the mediolateral (ML) width/anteroposterior (AP) length of simulated resected femoral condyle and tibia with the ML/AP dimensions of components offered by 4 current TKA systems.

RESULTS

Simulated resected male femurs tended to be wider than most TKA system components for a given AP size, probably leading to component ML underhang. Altogether, systems studied accommodated most AP and ML measurements of female condyles. However, we identified subsets of Hispanic female patients with certain AP lengths and/or ML widths that particular knee systems could not accommodate. Resected male and female tibias tended to be slightly narrower than all TKA systems for a given AP size.

CONCLUSION

The results of our study provide valuable data concerning the unique morphology of the Hispanic knee. These data can assist surgeons in the selection of the most suitable TKA systems for these patients.

Safety and Efficacy of 6.2 mm Patellar Button in Resurfacing Less than 20 mm Thin Patella: A Matched Pair Analysis

Purpose

Restoring the native patellar thickness after patellar resurfacing provides optimal function of the knee after arthroplasty and minimises complications related to the patellofemoral articulation. The aim of this study was to assess the usefulness of a thin patellar button (6.2 mm) in patients with a patella thickness of less than 20 mm during total knee arthroplasty.

Materials and Methods

This is a retrospective case control study. A total of 54 female patients with an intraoperative patellar thickness of <20 mm, resurfaced with a patellar button of 6.2 mm in thickness were identified (group 1). They were matched with 54 patients with a patellar thickness of 20–23 mm, resurfaced with a patellar button of 8 mm (group 2), based on age, sex, body mass index, and deformity. A clinical and radiological evaluation was done at a minimum 2-year follow-up.

Results

The preoperative mean patellar thickness was 18.94±1.07 mm and was restored to 19.06±0.79 mm in group 1, as compared to 21.63±0.99 mm and 21.72±0.99 mm in group 2. The mean postoperative range of motion was 122.22°±9.25° in group 1 and 123.52°±8.72° in group 2 (p=0.13). No patellar bone or button related complications were observed in any patient in either group.

Conclusions

The 6.2 mm thin patella is useful to restore the native thickness in patients with a patellar thickness of less than 20 mm without risk of button fracture, loosening or overstuffing.

Effect of shape on bone cement polymerization time in knee joint replacement surgery

BACKGROUND

Although many factors are known to influence the polymerization time of bone cement, it remains unclear which bone cement shape predicts the precise polymerization time. The purpose of this study was to investigate whether different cement shapes influenced polymerization time and to identify the relationship between cement shape and ambient operating theater temperature, relative humidity, and equilibration time.

METHODS

Samples were gathered prospectively from 237 patients undergoing primary total knee arthroplasty. The cement components were made into 2 different shapes: lump and pan. The time at which no macroscopic indentation of both cement models was possible was recorded as the polymerization time.

RESULTS

There was no significant difference between hand mixing (lump shape: 789.3 ± 128.4 seconds, P = .591; pan shape: 899.3 ± 152.2 seconds, P = .584) and vacuum mixing (lump shape: 780.2 ± 131.1 seconds, P = .591; pan shape: 909.9 ± 143.3 seconds, P = .584) in terms of polymerization time. Conversely, the polymerization time was significantly shorter for Antibiotic Simplex (lump shape: 757.4 ± 114.9 seconds, P = .001; pan shape: 879.5 ± 125.0 seconds, P < .001) when compared with Palacos R+G (lump shape: 829.0 ± 139.3 seconds, P = .001; pan shape: 942.9 ± 172.0 seconds, P < .001). Polymerization time was also significantly longer (P < .001) for the pan shape model (904 ± 148.0 seconds) when compared with the lump shape model (785.2 ± 129.4 seconds). In addition, the polymerization time decreased with increasing temperature (lump shape: R = 0.334, P < .001; pan shape: R = 0.375, P < .001), humidity (lump shape: R = 0.091, P < .001; pan shape: R = 0.106, P < .001), and equilibration time (lump shape: R = 0.073, P < .001; pan shape: R = 0.044, P < .001).

CONCLUSIONS

The polymerization time was equally affected by temperature, relative humidity, and equilibration time regardless of bone cement shape. Furthermore, the pan shape model better reflected the cement polymerization time between implant and bone compared with the lump shape model. The current findings suggest that, clinically, constant pressure with the knee in <45° of flexion needs to be applied until remaining pan shaped cement is completely polymerized.

Quality of life after total knee arthroplasty

Total knee arthroplasty (TKA) results in a high degree of patient satisfaction, as it provides patients with considerable medium- and long-term benefits in terms of quality of life, pain relief and function. Nevertheless, the literature reports that up to 30% of patients are dissatisfied. This dissatisfaction is directly related to the patients' quality of life, which they deem insufficient. Their quality of life depends on many physical, behavioural, social and psychological factors that are not taken into account by functional outcome scores. After describing the principles of quality of life evaluation after TKA, we will assess the effects of patient-related factors, the surgical technique and postoperative program through an exhaustive review of the literature. Patient expectations after TKA will then be outlined, particularly return to work and return to sports.

Annual trends in knee arthroplasty and tibial osteotomy: Analysis of a national database in Japan

BACKGROUND

Various nationwide studies have reported differing annual trends in utilization of knee arthroplasty and tibial osteotomy. Using the Diagnosis Procedure Combination database in Japan, the present series examined annual trends and demographics in total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA) and tibial osteotomy.

METHODS

All patients were identified who underwent TKA, UKA or tibial osteotomy for osteoarthritis, osteonecrosis or rheumatoid arthritis of the knee between July 2007 and March 2015.

RESULTS

A total of 170,433 cases of TKA, 13,209 cases of UKA and 8760 cases of tibial osteotomy were identified. The proportion of patients undergoing UKA rose from 4.0% in 2007 to 8.1% in 2014 (P<0.001), and that of tibial osteotomy from 2.6% in 2007 to 5.5% in 2014 (P<0.001); the proportion undergoing TKA fell from 93.4% in 2007 to 86.3% in 2014 (P<0.001). Between 2007 and 2014 the proportions of patients with osteonecrosis who underwent UKA and tibial osteotomy increased from 34.7% and 11.6% to 38.6% and 16.2%, respectively (P=0.001 for UKA and P=0.004 for tibial osteotomy). The proportions of patients with osteonecrosis undergoing UKA or tibial osteotomy were significantly greater than those with other diagnoses (P<0.001 for both).

CONCLUSIONS

The popularity of UKA and tibial osteotomy in Japan increased during the period 2007-2014 at the expense of TKA. The proportions of UKA and tibial osteotomy in patients with osteonecrosis also increased, and were larger than those in patients with other causative diseases.

Comparison of kinematic and mechanical alignment techniques in primary total knee arthroplasty: A meta-analysis

BACKGROUND

This meta-analysis compared clinical and radiographic outcomes and complications of kinematic alignment (KA) and mechanical alignment (MA) techniques in primary total knee arthroplasty (TKA).

METHODS

All studies comparing the operation time, change in hemoglobin, length of hospital stay, postoperative complications, and clinical and radiographic outcomes as assessed with various measurement tools, from direct interview to imaging methods, in patients who underwent primary TKA through the KA or MA technique were included.

RESULTS

Six studies were included in the meta-analysis. The proportion of patients who developed postoperative complications (OR: 1.10, 95% CI: 0.49-2.46; P = .69) did not differ significantly between the KA and MA techniques. The 2 groups were also similar in terms of change in hemoglobin (95% CI: -0.38 to 0.34; P = .91), length of hospital stay (95% CI: -0.04 to 0.55; P = .10), hip-knee-ankle angle (95% CI: -1.76 to 0.75; P = .43), joint line orientation angle (95% CI: -4.27 to 4.23; P = .99), tibial component slope (95% CI: -0.53 to 3.56; P = .15), and femoral component flexion (95% CI: -2.61 to 7.57; P = .34). In contrast, operation time (95% CI: -27.16 to -3.71; P = .01), overall functional outcome (95% CI: 6.59-11.51; P < .0001), knee anatomical axis (95% CI: -1.38 to -0.01; P = .05), femoral component relative to the mechanical axis (95% CI: -2.47 to -1.40; P < .0001), and tibial component relative to the mechanical axis (95% CI: 1.56-2.95; P < .0001) were significantly different between the 2 groups.

CONCLUSIONS

There were no significant differences in postoperative complications, change in hemoglobin, length of hospital stay, hip-knee-ankle angle, joint line orientation angle, tibial component slope, or femoral component flexion between the KA and MA techniques for primary TKA. However, the KA technique resulted in a significantly shorter operation time and better overall functional outcome than the MA technique, even though the femoral component was placed in a slightly more valgus position relative to the mechanical axis and the tibial component in a slightly more varus position with the KA technique.

Area of Skin Numbness After Total Knee Arthroplasty: Does Minimally Invasive Approach Make Any Difference From Standard Approach?

BACKGROUND

Skin numbness after total knee arthroplasty (TKA) was reported in relation to injury of the infrapatellar branch of saphenous nerve (IPBSN).

METHODS

Phase I study: A nonrandomized and nonconsecutive selection of 30 patients undergoing unilateral TKA, using minimally invasive surgery approach, and 30 patients having standard approach were included. Area of skin numbness was periodically evaluated and compared until 1-year follow-up (FU). Phase II study: we dissected 15 normal cadaveric knees and followed the course and distribution of IPBSN.

RESULTS

Twenty-nine predominantly female patients in each group completed 1-year FU with no differences in demographic data. Both the groups had significantly improved Knee Society Score clinical and function scores with no statistical differences. The numb areas in both the groups similarly decreased from 2 weeks (51.7 cm² vs 51.1 cm²) to 1 year (2.1 cm² vs 2.4 cm²) with similar percentages of no skin numbness at 1 year (69% vs 65%). The IPBSN branched from saphenous nerve before exiting the adductor canal and ran longitudinally and obliquely. It was found as a single nerve in 20%, a 2-branch nerve in 67% and a 3-branch nerve in 13%. All branches crossed the knee midline between superior patellar pole and tibial tubercle.

CONCLUSION

Clinical study showed that TKA using minimally invasive surgery approach provided similar area of skin numbness to standard approach. Numbness area gradually decreased at serial FUs in both the groups. The cadaveric study demonstrated that the IPBSN consistently gave no branch passing the knee midline above superior patellar pole.