General anesthesia is not associated with dementia in older adults with osteoarthritis for hip/knee replacements, a national population-based nested case-control study

BACKGROUND

Dementia is a prevalent neurological condition, yet the relationship between dementia and general anesthesia remains uncertain. The study aimed to explore the association between general anesthesia and dementia using a nationwide population-based database.

METHODS

The study extracted data from Taiwan's national health insurance, which encompassed the records of one million insured residents. A total of 59,817 patients aged 65 years and above, diagnosed with osteoarthritis between 2002 and 2010, were included. Among these patients, 3277 individuals with an initial diagnosis of dementia between 2004 and 2013 were matched with non-dementia patients based on age, gender, and the date of osteoarthritis diagnosis. Following a 1:2 random matching, the case group included 2171 patients with dementia, while the control group consisted of 4342 patients without dementia. The data was analyzed using conditional and unconditional logistic regressions.

RESULTS

No significant differences in the odds of dementia were found between individuals exposed to general and regional anesthesia during hip/knee replacement surgeries (OR = 1.11; 95%CI: 0.73-1.70), after adjusting for age, sex, and co-morbidities. Similarly, there were no significant differences in the odds of dementia based on different durations of anesthesia exposure (General: <2 h: OR = 0.91, 95%CI = 0.43-1.92; 2-4 h: OR = 1.21, 95%CI = 0.82-1.79; >4 h: OR = 0.39, 95%CI = 0.15-1.01; compared to no exposure. Regional: <2 h: OR = 1.18, 95%CI = 0.85-1.62; 2-4 h: OR = 0.9, 95%CI = 0.64-1.27; >4 h: OR = 0.55, 95%CI = 0.15-1.96; compared to no exposure). Likewise, no significant differences were observed in the odds of dementia based on the number of replacement surgeries (twice: OR = 0.74, 95%CI = 0.44-1.23, compared to once).

CONCLUSION

Neither general anesthesia nor regional anesthesia in hip/knee surgery was associated with dementia. Different numbers and durations of anesthesia exposure showed no significant differences in the odds for dementia.

Three-dimensional texture analyses of multi-quantitative relaxation time maps for evaluating cartilage repair with the treatment of allogeneic human adipose-derived mesenchymal progenitor cells

BACKGROUND

To explore the ability of three-dimensional texture analyses based on gray-level run-length matrix (GLRLM) for examining the spatial distribution of pixel values on magnetic resonance imaging (MRI) relaxation time maps and detecting the compositional variation of cartilage repair following treatment with allogeneic human adipose-derived mesenchymal progenitor cells (haMPCs).

METHODS

Participants with knee osteoarthritis were randomly divided into three groups with intra-articular haMPCs injections: low-, medium-, and high-dose groups. We analyzed five GLRLM parameters in the T1rho, T2 and T2star maps, including run length non-uniformity (RLNonUni), gray-level non-uniformity (GLevNonU), long run emphasis (LngREmph), short run emphasis (ShrtREmp), and fraction of images in runs. We used the relative D values (the ratio of difference values to baseline) as the objective to avoid errors caused by individual differences. We calculated the two-tailed Pearson's linear correlation coefficient (r) to investigate the correlations of the texture parameters with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores.

RESULTS

Compared with the base time, significant reduction of WOMAC score was observed in both high and medium doses groups at terminal time, indicating relief of pain symptoms in high and medium groups with the treatment of allogeneic haMPCs. Significant differences were observed in the GLRLM parameters of cartilage MR relaxation time maps in different doses groups. In both T1rho and T2 relaxation time maps, the high-dose group showed significant increases in relative D values of RLNonUni, GLevNonU, LngREmph and ShrtREmp, which indicated significant changes in the uniformity of relaxation time maps. For T2star map, GLRLM parameters such as GLevNonU and ShrtREmp, especially LngREmph, showed significant increases in relative D values in high-dose group. Among all GLRLM features, LngREmph of three relaxation time maps had performed excellent linear correlations with WOMAC scores.

CONCLUSIONS

Texture analysis of the cartilage may allow the detection of compositional variation in cartilage repair with the treatment of allogeneic haMPCs. This technique displays potential applications in understanding the mechanism of stem cell repair of the cartilage and assessing the treatment response.

Impact of Hip and Knee Osteoarthritis on Full Body Sagittal Alignment and Compensation for Sagittal Spinal Deformity

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD).

BACKGROUND

Spine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD.

PATIENTS AND METHODS

In total, 527 preoperative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full-body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation.

RESULTS

The mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, and 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment ( P <0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt ( P =0.001) and sacrofemoral angle ( P <0.001), but increased knee flexion ( P =0.012). Regression analysis revealed that with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis ( r2 =0.812). Hip osteoarthritis decreased compensation through sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-coefficient=0.100).

CONCLUSIONS

For the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis.

Patient-Reported Outcomes Measurement Information System Physical Function and Global Physical Health Subscale Strongly Correlate and Perform Similarly to the Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form

BACKGROUND

Arthroplasty surgeons use a variety of patient-reported outcome measures (PROMs) to assess functional well-being, including the Knee Injury and Osteoarthritis Outcome Score (KOOS) Physical Function short form (KOOS-PS), Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Short Form 10a (PROMIS PF SF 10a), and PROMIS Global-10 Physical Health subscale. However, there is a paucity of literature assessing their concurrent validity and performance.

METHODS

Between June 2016 and December 2020, patient visits at an arthroplasty clinic for knee concerns were identified. Patients who completed KOOS-PS, PROMIS PF SF 10a, and PROMIS Global-10, including its physical and mental health subscales, at the same visit were identified. Spearman rho (ρ) correlations were calculated and ceiling and floor effects identified. Overall, 5,303 patient encounters were included.

RESULTS

Among physical function domains, strong correlation existed between the KOOS-PS and PROMIS PF SF 10a (ρ = 0.76, P < .001), KOOS-PS and PROMIS Global Physical Health (ρ = 0.71, P < .001), and PROMIS PF SF 10a and PROMIS Global Physical Health (ρ = 0.78, P < .001). No physical function-focused PROM had an appreciable floor effect (ie, at or more than 1%). The KOOS-PS had a small but measurable ceiling effect (n = 105 [2.0%]).

CONCLUSIONS

All of the examined PROMs are acceptable to measure the functional status of patients with knee pathology, with the PROMIS Global-10 also being able to capture elements of mental health too. The PROMIS Global-10 may be of most value of the PROMs assessed, as the United States Centers for Medicare and Medicaid Services already incorporate the mental health component into new alternative payment models.

Predicting the onset of end-stage knee osteoarthritis over two- and five-years using machine learning

OBJECTIVE

Identifying participants who will progress to advanced stage in knee osteoarthritis (KOA) trials remains a significant challenge. Current tools, relying on total knee replacements (TKR), fall short in reliability due to the extraneous factors influencing TKR decisions. Acknowledging these limitations, our study identifies a critical need for a more robust metric to assess severe KOA. The end-stage KOA (esKOA) measure, which combines symptomatic and radiographic criteria, serves as a solid indicator. To enhance future trials that use esKOA as an endpoint, our study focuses on developing and validating a machine-learning tool to identify individuals likely to develop esKOA within 2 to 5 years.

DESIGN

Utilizing the Osteoarthritis Initiative (OAI) data, we trained models on 3,114 participants and validated them with 606 participants for the right knee, and similarly for the left knee, with external validation from the Multicentre Osteoarthritis Study (MOST) involving 1,602 participants. We aimed to predict esKOA onset at 2-to-2.5 years and 4-to-5 years, defining esKOA by severe radiographic KOA with moderate/severe symptoms or mild/moderate radiographic KOA with persistent/intense symptoms. Our analysis considered 51 candidate predictors, including demographics, clinical history, physical examination, and X-ray evaluations. An online tool predicting esKOA progression, based on models with ten and nine predictors for the right and left knees, respectively, was developed.

RESULTS

External validation (MOST) for the right knee at 2.5 years yielded an Area Under Curve (AUC) of 0.847 (95 % CI 0.811 to 0.882), and at 5 years, 0.853 (95 % CI 0.823 to 0.881); for the left knee at 2.5 years, AUC was 0.824 (95 % CI 0.782 to 0.857), and at 5 years, 0.807 (95 % CI 0.768 to 0.843). Models with fewer predictors demonstrated comparable performance. The online tool is available at: https://eskoa.shinyapps.io/webapp/.

CONCLUSION

Our study unveils a robust, externally validated machine learning tool proficient in predicting the onset of esKOA over the next 2 to 5 years. Our tool can lead to more efficient KOA trials.

Superior Pain Reduction with Anteromedialization Tibial Tubercle Osteotomy Versus Non-Operative Management for Patellofemoral Osteoarthritis

PURPOSE

The purpose of this study was to compare the clinical outcomes of patients with patellofemoral osteoar-thritis (PFOA) treated non-operatively with those treated operatively with an unloading anteromedialization tibial tubercle osteotomy (TTO).

METHODS

A retrospective chart review was performed to identify patients with isolated PFOA who were either managed non-operatively or surgically with a TTO and who had a minimum follow-up of 2 years. Patients were surveyed with the visual analog scale (VAS) for pain, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), Anterior Knee Pain scale (Kujala), and Tegner Activity scale. Statistical analysis included two-sample t-testing, one-way ANOVA, and bivariate analysis.

RESULTS

The clinical outcomes of 49 non-operatively managed patients (mean age: 52.7 ± 11.3 years; mean follow-up: 1.7 ± 1.0 years) and 35 operatively managed patients (mean age: 31.8 ± 9.4 years; mean follow-up: 3.5 ± 1.7 years) were assessed. The mean VAS improved sig-nificantly in both groups [6.12 to 4.22 (non-operative), p < 0.0001; 6.94 to 2.45 (TTO); p < 0.0001], with operatively treated patients having significantly lower postoperative pain than non-operatively managed patients at the time of final follow-up [2.45 (TTO) vs. 4.22 (non-operative), p < 0.001]. The mean KOOS-JR score was significantly greater in the operative group at time of final follow-up [78.7 ± 11.6 (TTO) vs. 71.7 ± 17.8 (non-operative), p = 0.035]. There was no significant difference in Kujala or Tegner scores between the treatment groups. Additionally, there was no sig-nificant relationship between the number of intra-articular injections, duration of NSAID use, and number of physical therapy sessions on clinical outcomes in the non-operatively treated group (p > 0.05).

CONCLUSIONS

An unloading anteromedialization TTO provides significantly better pain relief and restoration of function compared to non-operative management in the treatment of symptomatic PFOA.

Risks Following Total Knee Arthroplasty in Patients Who Have Antiphospholipid Syndrome

BACKGROUND

Antiphospholipid syndrome (APS) is recognized as a thrombophilic autoimmune condition characterized by a tendency to develop venous thromboembolism. Total knee arthroplasty (TKA) is a prevalent procedure in patients who have advanced knee arthritis. Notably, TKA is unequivocally considered a thrombotic risk factor. However, outcomes of APS patients after TKA are still poorly documented in literature. The purpose of this study was to evaluate APS as a potential risk factor for complications after TKA.

METHODS

Using the PearlDiver Mariner database from 2010 to 2022, APS patients undergoing primary TKA were identified and compared to 10:1 matched control based on age, sex, and relevant comorbidities. A total of 7,478 patients undergoing primary TKA were analyzed, of which 683 had APS. Multivariable logistic regression analyses were done for medical complications up to 90 days and surgical complications including revision up to 2 years. Ninety-day emergency department visit and inpatient readmission were also documented.

RESULTS

Within 90 days after TKA, patients who have APS exhibited higher rates of cerebrovascular accident (adjusted odds ratio 2.04, 95% confidence interval 1.12 to 3.57; P = .014) and deep vein thrombosis (adjusted odds ratio 2.87, 95% confidence interval 1.99 to 4.06; P < .001) as compared to matched controls. No difference in surgical or nonthrombotic medical complications was observed between 2 cohorts.

CONCLUSIONS

There were significantly higher rates of stroke and deep vein thrombosis in APS patients. Our study did not find statistical differences in other surgical complications or readmissions between the 2 groups. Orthopaedic surgeons should consider appropriate prophylaxis of thrombosis in this patient population undergoing TKA perioperatively.

Comparison of Responsiveness of Patient-Reported Outcome Measures After Total Knee Arthroplasty

BACKGROUND

The aim of this study was to evaluate the responsiveness of different patient-reported outcome measures in patients with primary total knee arthroplasty (TKA).

METHODS

In this prospective observational study, we assessed patients with TKA before the surgery, after 4 months, after 1 year, and after 2 years. Measures were the objective Knee Society Score (KSS) and the following patient-reported outcome measures: Knee injury and Osteoarthritis Outcome Score (KOOS), KOOS-12, Forgotten Joint Score (FJS-12), High-Activity Arthroplasty Score, and EQ-5D-3L. Responsiveness was determined by effect size (ES), standardized response mean (SRM), area under the receiver operating characteristics curve, floor and ceiling effects, and hypothesis testing.

RESULTS

We analyzed data from 309 TKAs (272 patients, 56% female). The ES and SRM for the change in KSS, KOOS, KOOS-12, FJS-12, and EQ-5D-3L from baseline to each follow-up were large (>0.8). The largest responsiveness from baseline to follow-up was found for the KSS, KOOS/KOOS-12 quality of life, KOOS-12 summary, KOOS-12 pain, and FJS-12 (2.0 > ES <3.9, 1.4 > SRM <2.4). The area under the curve from baseline to each follow-up was ≥0.7 for KOOS, KOOS-12, and FJS-12 (range 0.71 to 0.95) and <0.7 for KSS and EQ-5D-3L (range 0.65 to 0.74). We found floor or ceiling effects in the KOOS, KOOS-12, and EQ-5D-3L, but not in the KSS, FJS-12, and High-Activity Arthroplasty Score.

CONCLUSIONS

Our study demonstrated that responsiveness differed between the various measures. The KOOS-12 and FJS-12 showed the greatest internal and external responsiveness, although ceiling effects occurred in the KOOS-12.

Predictors for the Knee Extension Strength at 2 Yrs After Total Knee Arthroplasty Using Regression Tree Analysis

OBJECTIVE

The aim of the study is to clarify the interactive combinations of clinical factors associated with knee extension strength 2 yrs after total knee arthroplasty.

DESIGN

A retrospective cohort study was conducted on 264 patients who underwent total knee arthroplasty. Knee extension strength was assessed preoperatively, 3 wks, and 2 yrs after total knee arthroplasty. Physical functions were measured with 10-m walking test, Timed Up and Go test, one-leg standing time, isometric knee flexion strength, knee joint stability, knee pain, femora-tibial angle, and passive knee extension and flexion angle before surgery as a baseline and 3 wks after total knee arthroplasty as acute phase. Regression tree analysis was conducted to clarify the interactive combinations that accurately predict the knee extension strength 2 yrs after total knee arthroplasty.

RESULTS

Operational side knee extension strength (>1.00 Nm/kg) at acute phase was the primal predictor for the highest knee extension strength at 2 yrs after total knee arthroplasty. Acute phase Timed Up and Go test (≤10.13 secs) and baseline 10-m walking test (≤11.72 secs) was the second predictor. Acute phase nonoperative side knee extension strength (>0.90 Nm/kg) was also selected as the predictor.

CONCLUSIONS

This study demonstrated that knee extension strength or Timed Up and Go test in the acute phase and 10-m walking test before total knee arthroplasty are useful for estimating the knee extension strength after total knee arthroplasty. The results will help determine specific postoperative rehabilitation goals and training options.

Kinematic Performance of Medial Pivot Total Knee Arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) implants have continued to evolve to accommodate new understandings of knee mechanics. The medial-pivot implant is a newer design, which is intended to limit anterior-posterior translation in the medial compartment while allowing lateral compartment translation. However, evidence for a generalized medial-pivot characteristic across all activities is limited. The purpose of the study was to quantify and compare in vivo knee joint kinematics using high-speed stereo radiography during activities of daily living in patients who have undergone a TKA with a cruciate sacrificing medial-pivot implant to age-matched and sex-matched native controls.

METHODS

Fifteen participants (7 patients, 4 women, mean age 70 years and 8 nonsymptomatic controls, 4 women, mean age 64 years) performed 6 functional tasks in high-speed stereo radiography: deep-knee lunge, chair rise, step down, gait, gait with 90° turn, and seated knee extension. Translational differences between groups (surgical versus control) were assessed for the medial and lateral condyle, while pivot location was normalized to subject-specific tibial plateau geometry.

RESULTS

The surgical cohort displayed a more constrained medial condyle that provided greater stability of the medial compartment and did not result in the paradoxical anterior translation at mid-flexion angles during weight-bearing activities, but was associated with less condylar translation than native knees. Additionally, the transverse tibial pivot location occurs most commonly in the middle third of the tibial plateau and secondarily on the medial third.

CONCLUSIONS

Some variability in pivot location occurs between activities and is more in nonsymptomatic, native knee controls.

Patient Acceptable Symptom State Thresholds for the Knee Society Score, Oxford Knee Score, and 36-Item Short Form Survey Ten Years Following Unicompartmental Knee Arthroplasty

BACKGROUND

The patient acceptable symptom state (PASS) refers to a cutoff value on any patient-reported outcome measures (PROMs) scale, beyond which patients consider themselves as having achieved an acceptable outcome. This study aimed to identify PASS thresholds for knee-specific and generic PROMs at 10 years post-unicompartmental knee arthroplasty (UKA).

METHODS

There were 269 patients who underwent UKA for medial osteoarthritis from 2004 to 2007 at a single institution and were surveyed preoperatively and 10 years postoperatively using the Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS), Oxford Knee Score (OKS), 36-Item Short Form Survey (SF-36) Mental Component Score (MCS), and SF-36 Physical Component Score (PCS). Treatment outcomes and expectations were assessed using an anchor question, and PASS attainment was determined using the Youden index on a receiver operating characteristic (ROC) curve. Also, a similar study that identified 2-year long-term PROM PASS thresholds for UKA was referenced and compared.

RESULTS

Overall, 91.1% reported acceptable outcomes. The area under the curve for ROCs of KSKS, OKS, and PCS were 0.80, 0.75, and 0.71, respectively. The area under the curve for ROCs of KSFS and MCS were both 0.64. The PASS thresholds were 67.5 for KSFS, 70.5 for KSKS, 39.5 for OKS, 44.6 for PCS, and 43.8 for MCS. Patients who achieved a PASS were at least 3 times more likely to have satisfactory outcomes.

CONCLUSIONS

To our knowledge, this is the first study that identified 10-year long-term PROM PASS thresholds for UKA. Accounting for our finding that a decade-long follow-up yielded lower PASS thresholds, time-specific UKA PROM PASS thresholds should be considered.

LEVEL OF EVIDENCE

III.

Lateral Subvastus Lateralis versus Medial Parapatellar Approach for Total Knee Arthroplasty: Patient Outcomes and Kinematics Analysis

The conventional approach for total knee arthroplasty (TKA) is a medial parapatellar approach (MPA). We aimed to study patient outcomes and kinematics with a quadriceps sparing lateral subvastus lateralis approach (SLA). Patients with neutral/varus alignment undergoing primary TKA were consented to undergo the SLA. At 1-year postoperative, patients underwent radiostereometric analysis. Patients were administered the Short Form 12 (SF-12), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Society Score (KSS). Kinematics and outcome data were compared to a group undergoing TKA via conventional MPA. Fourteen patients underwent TKA via SLA with a mean age 71.5 ± 8.0 and mean body mass index (BMI) 31.0 ± 4.5. The MPA group had 13 patients with mean age 63.4 ± 5.5 (p = 0.006) and mean BMI 31.2 ± 4.6 (p = 0.95). The SLA resulted in a significantly more posterior medial contact point at 0 (p = 0.011), 20 (p = 0.020), and 40 (p = 0.039) degrees of flexion. There was no significant difference in medial contact point from 60 to 120 degrees, lateral contact point at any degree of flexion, or axial rotation. There was no difference in improvement in postoperative WOMAC, SF-12, KSS function, and total KSS knee scores between groups. The MPA group had a significantly greater improvement in KSS knee scores at 3 months (p < 0.001), 1 year (p = 0.003), and 2 years (p = 0.017). The SLA resulted in increased medial femoral rollback early in flexion. Although both approaches resulted in improved postoperative outcomes, the MPA group showed significantly greater improvements in KSS knee scores at 3 months, 1 year, and 2 years. Further studies are required to identify any benefits that the SLA may offer. LEVEL OF EVIDENCE:  Therapeutic Level II.

The Utilization of Press-Fit Total Knee Arthroplasty is Not Evenly Distributed: A National Registry Review

BACKGROUND

This study evaluates trends of cemented versus press-fit total knee arthroplasty (TKA). We hypothesized that press-fit TKA is more common in younger and obese patients. There may also be racial, geographic, and institutional variation.

METHODS

The American Joint Replacement Registry was used to conduct a retrospective review of primary TKA procedures for osteoarthritis in the United States between January 2019 and March 2022. The objective was to identify differences in incidence, demographics, body mass index (BMI), Charlson Comorbidity Index (CCI), and institutional teaching status (teaching vs. non-teaching) between press-fit and cemented TKAs.

RESULTS

Two hundred ninety-seven thousand four hundred two patients (61% female, average age 68 years, 88.3% White) underwent cemented TKA versus 50,880 patients (52% female, average age 65 years, 89% White) underwent press-fit TKA. Overall, 20.8% of press-fit versus 19.9% of cemented TKA had a BMI of 35 to 39.9 and 15.2% of press-fit versus 12.5% of cemented TKA had BMI >40 ( P < 0.001). Patients undergoing press-fit TKA were less likely Black (OR = 0.727; P < 0.0001), Asian (OR = 0.651, P < 0.0001), and Native Hawaiian/other Pacific Islander (OR = 0.705, P < 0.02) with White as the reference group. Northeastern and Southern United States were more likely to use press-fit TKA than the Midwest (OR = 1.89 and OR = 1.87, P < 0.0001) and West (OR = 1.67; and OR = 1.65; P < 0.0001). Press-fit TKA incidence in 2019 was 9.9% versus 20.6% in 2022 ( P < 0.001).

CONCLUSION

Press-fit TKA is increasingly more common in Northeastern and Southern United States, and patients are older than expected. Patients with BMI >35 had a slightly higher rate of undergoing press-fit than cemented TKA. Notable racial differences also exist. Additional research addressing racial disparities and evaluating longevity of press-fit designs is needed.

Survivorship and Outcomes of Robotic Arm-Assisted Medial Unicompartmental Knee Arthroplasty at a Minimum of 5-Year Follow-Up

PURPOSE

This study aimed to evaluate implant survivor-ship, complications, and re-operation rates following robotic arm-assisted unicompartmental knee arthroplasty (UKA) at mid-term follow-up.

METHODS

Patient satisfaction, clinical outcome, and knee alignment restoration were evaluated. All patients undergo-ing robotic arm-assisted medial UKA during a 2-year period were prospectively enrolled. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, varus-valgus deformity, and knee range of motion were studied pre- and postoperatively. Revisions and surgery-related complications were recorded.

RESULTS

Eighty-five patients were included in the study (mean age: 71.2 years). The mean follow-up was 74.7 months. One conversion to total knee arthroplasty was performed due to periprosthetic fracture 4.5 years after initial surgery result-ing in a survivorship rate of 98.8%. Overall satisfaction was excellent; 97.7% of patients were satisfied or very satisfied, while none was dissatisfied or very dissatisfied. WOMAC score in total, as well as in each component, exhibited sig-nificant improvement postoperatively. Additionally, knee alignment in the coronal plane as well as flexion contracture were significantly improved following the procedure.

CONCLUSIONS

The outcomes of the present cohort revealed that precise prosthesis implantation through the robotic arm-assisted system in UKA provided excellent overall satisfac-tion rates and clinical outcomes at mid-term follow-up.

Preoperative and Postoperative Weight Change has Minimal Influence on Health Care Utilization and Patient-Reported Outcomes Following Total Knee Arthroplasty

As obesity becomes more prevalent, more patients are at risk of lower extremity osteoarthritis and subsequent total knee arthroplasty (TKA). This study aimed to test (1) the association of preoperative weight change with health care utilization and (2) the association of pre- and postoperative weight changes with failure to achieve satisfaction and minimal clinically important difference (MCID) in Knee injury and Osteoarthritis Outcome Score for pain (KOOS-Pain) and function (KOOS-PS) 1 year after TKA. Prospectively collected monocentric data on patients who underwent primary TKA were retrospectively reviewed. Multivariable logistic regression assessed the influence of BMI and weight change on outcomes while controlling for confounding variables. Outcomes included prolonged length of stay (LOS >3 days), nonhome discharge, 90-day readmission rate, satisfaction, and achievement of MCID for KOOS-Pain and KOOS-PS. Preoperative weight change had no impact on prolonged LOS (gain, p = 0.173; loss, p = 0.599). Preoperative weight loss was associated with increased risk of nonhome discharge (odds ratio [OR]: 1.47, p = 0.003). There was also increased risk of 90-day readmission with preoperative weight gain (OR: 1.27, p = 0.047) and decreased risk with weight loss (OR: 0.73, p = 0.033). There was increased risk of nonhome discharge with obesity class II (OR: 1.6, p = 0.016) and III (OR: 2.21, p < 0.001). Weight change was not associated with failure to achieve satisfaction, MCID in KOOS-Pain, or MCID in KOOS-PS. Obesity class III patients had decreased risk of failure to reach MCID in KOOS-Pain (OR: 0.43, p = 0.005) and KOOS-PS (OR: 0.7, p = 0.007). Overall, pre- and postoperative weight change has little impact on the achievement of satisfaction and clinically relevant differences in pain and function at 1 year. However, preoperative weight gain was associated with a higher risk of 90-day readmissions after TKA. Furthermore, patients categorized in Class III obesity were at increased risk of nonhome discharge but experienced a greater likelihood of achieving MCID in KOOS-Pain and KOOS-PS. Our results raise awareness of the dangers of using weight changes and BMI alone as a measure of TKA eligibility.

The impact of comorbidity status on knee function 1 year after total knee arthroplasty: a population-based cohort study

BACKGROUND AND PURPOSE

Few studies have examined the impact of comorbidity on functional and clinical knee scores after primary total knee arthroplasty (TKA). We compared the effect of having a high Charlson Comorbidity Index (CCI), relative to a low CCI, on changes in the American Knee Society Score (AKSS) functional and clinical scores from baseline to week 52 after TKA in patients with knee osteoarthritis (OA).

METHODS

This population-based cohort study included 22,533 patients identified in the Danish Knee Arthroplasty Register from 1997 to 2021. Patients were classified as having low, medium, or high comorbidity based on CCI. The outcome was defined as the mean change (from preoperative to 1-year post-TKA) in functional and clinical knee scores measured by the AKSS (0-100). The association was analyzed using multiple linear regression by calculating mean change scores adjusting for sex, age, weight, cohabiting status, and baseline AKSS.

RESULTS

The prevalence of patients with low, medium, and high comorbidity was 75%, 21%, and 4%, respectively. The mean change score in functional AKSS for patients with high comorbidity was -6 points (95% confidence interval [CI] -7 to -5) compared with low comorbidity. The mean change score in clinical AKSS for patients with high comorbidity was -1 point (CI -2 to 0) compared with low comorbidity.

CONCLUSION

Patients with knee OA and medium or high comorbidity can expect similar improvements in functional and clinical AKSS after TKA to patients with low comorbidity.

[Comparison of the effects of sciatic nerve block combined with continuted femoral nerve block or continuted adductor canal block on pain and motor function after total knee arthroplasty]

Objective

To compare the effect of sciatic nerve block (SNB) combined with continuted femoral nerve block (FNB) or continuted adductor canal block (ACB) on pain and motor function after total knee arthroplasty (TKA).

Methods

A total of 60 patients with TKA-treated osteoarthritis of the knee who met the selection criteria were enrolled between November 2020 and February 2021 and randomised allocated into the study group (SNB combined with continuted ACB) and the control group (SNB combined with continuted FNB), with 30 cases in each group. There was no significant difference in gender, age, body mass, height, body mass index, preoperative Hospital for Special Surgery (HSS) score, femoral tibial angle, and medial proximal tibial angle between the two groups ( P>0.05). The operation time, the initial time to the ground, the initial walking distance, and the postoperative hospital stay were recorded. At 2, 4, 6, 12, 24, and 48 hours after operation, the numerical rating scale (NRS) score was used to evaluate the rest pain around the knee joint, the quadriceps femoris muscle strength was evaluated by the freehand muscle strength method, and the knee flexion and extension angles were measured.

Results

There was no significant difference in the operation time and initial walking distance between the two groups ( P>0.05); the initial time to the ground and postoperative hospital stay of the study group were significantly shorter than those of the control group ( P<0.05). Except for the 48-hour postoperative NRS score of the study group, which was significantly lower than that of the control group ( P<0.05), there was no significant difference in the NRS scores between the two groups at the remaining time points ( P>0.05). The quadriceps femoris muscle strength from 4 to 24 hours postoperatively and the knee extension angle from 2 to 6 hours postoperatively of the study group were significantly better than those of the control group ( P<0.05); the differences in the quadriceps femoris muscle strength and knee extension and flexion angles between the two groups at the remaining time points were not significant ( P>0.05).

Conclusion

SNB combined with either continuted ACB or continuted FNB can effectively relieve pain in patients after TKA, and compared with combined continuted FNB, combined continuted ACB has less effect on quadriceps femoris muscle strength, and patients have better recovery of knee flexion and extension mobility.

Preoperative Hindfoot Alignment and Outcomes After High Tibial Osteotomy for Varus Knee Osteoarthritis: We Walk on Our Heel, Not Our Ankle

UPDATE

This article was updated on May 15, 2024 because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 898, in the section entitled "Materials and Methods," the sentence that had read "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the center of the calcaneus (for the GA) or talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." now reads "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the lowest point of the calcaneus (for the GA) or the center of the talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." Likewise, in the legend for Figure 3 on page 899, the sentence that had read "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the center of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." now reads "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the lowest point of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." Finally, on page 903, "HKA" was changed to "HKA angle" in Table III.

BACKGROUND

The hip-to-calcaneus axis, previously known as the ground mechanical axis (GA), ideally passes through the center of the knee joint in the native knee. The aim of this study was to elucidate, with use of hip-to-calcaneus radiographs, changes in knee and hindfoot alignment and changes in outcomes following high tibial osteotomy (HTO).

METHODS

We reviewed the records for 128 patients who underwent HTO between 2018 and 2020. Patients were stratified into 2 groups, a hindfoot valgus group (n = 94) and a hindfoot varus group (n = 34), on the basis of their preoperative hindfoot alignment. The hindfoot alignment was evaluated with use of the hindfoot alignment angle (HAA). To evaluate lower-limb alignment, full-length standing posteroanterior hip-to-calcaneus radiographs were utilized to measure 4 radiographic parameters preoperatively and 2 years postoperatively: the hip-knee-ankle (HKA) angle, hip-knee-calcaneus (HKC) angle, and the weight-bearing line (WBL) ratios of the mechanical axis (MA) and GA.

RESULTS

The mean HAA improved significantly from 5.1° valgus preoperatively to 1.9° valgus postoperatively in the hindfoot valgus group (p < 0.001). In contrast, in the hindfoot varus group, the HAA showed no meaningful improvement in the coronal alignment of the hindfoot following HTO (p = 0.236). The postoperative mean HKC angle in the hindfoot varus group was 2° more varus than that in the hindfoot valgus group (1.0° versus 3.0°; p = 0.001), and the GA in the hindfoot varus group passed across the knee 8.0% more medially than that in the hindfoot valgus group (55% versus 63% from the most medial to the most lateral part of the tibial plateau). The hindfoot varus group had worse postoperative clinical outcomes than the hindfoot valgus group in terms of the mean Knee injury and Osteoarthritis Outcome Score for pain and American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score.

CONCLUSIONS

Although our findings did not provide sufficient evidence to establish clinically relevant differences between the groups, they indicated that the group with a preoperative fixed hindfoot varus deformity had a higher rate of undercorrection and worse clinical outcomes, especially pain, following HTO. Therefore, modification of the procedure to shift the GA more laterally may be required for these patients.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

The impact of diabetes status on pain and physical function following total joint arthroplasty for hip and knee osteoarthritis: variation by sex and body mass index

Few studies have examined diabetes impact on total joint arthroplasty (TJA) outcomes, with variable findings. We investigated the association between diabetes and post-TJA physical function and pain, examining whether diabetes impact differs by sex and BMI. Patient sample completed questionnaires within 3 months prior to hip or knee TJA for osteoarthritis (OA) and 1-year post-surgery. Surgical 'non-response' was defined as < 30% improvement in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and physical function at 1-year. Two adjusted logistic regression models were estimated: (1) excluding, (2) including an interaction between diabetes, sex and BMI. The sample (626 hip, 754 knee) was 54.9% female, had mean BMI of 30.1, 13.0% reported diabetes. In adjusted models excluding an interaction, diabetes was not associated with non-response. However, a significant 3-way interaction (physical function: p = 0.003; pain: p = 0.006) between diabetes, sex, and BMI was found and was associated with non-response: non-response probability increased with increasing BMI in men with diabetes, but decreased with increasing BMI in women in diabetes. Findings suggest uncertainty in diabetes impact may be due to differential impacts by sex and BMI. A simple consideration of diabetes as present vs. absent may not be sufficient, with implications for the large TJA population.

The interval between staged bilateral total knee arthroplasties does not affect early complications of the second knee or long-term function of the first and second knees

BACKGROUND

This study explored the optimal time interval between staged bilateral total knee arthroplasty (BTKA) to minimize early complications of the second TKA and maximise the long-term function of the first and second knees.

METHODS

We retrospectively reviewed 266 patients who underwent staged BTKA between 2013 and 2018. Groups 1-4 had time intervals between BTKAs of 1-6, 6-12, 12-18, and 18-24 months, respectively. Demographics, postoperative complications within 90 days of the second TKA, Knee Society Score (KSS), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) score were compared among the groups.

RESULTS

In total, 54, 96, 75, and 41 patients were assigned to groups 1-4, respectively. Although group 1 had the highest overall complication rate (11.11%), there was no significant difference in the complication rate among the four groups. Also, no significant differences were found among the four groups in functional and patient-reported outcomes, in either the first or second knee at 5 years postoperatively, including KSS-knee, KSS-function, WOMAC-pain, WOMAC-stiffness, and WOMAC-physical function. The interval between BTKA did not influence complications or the function of the second knee. The TKA type (posterior-stabilised vs. medial-pivot) and age did not correlate significantly with any scores.

CONCLUSIONS

There was no group difference in early complications of the second TKA, and postoperative function was equivalent between the two knees and did not vary by the interval between surgeries. The results of this study give surgeons and patients more choices. If patients cannot tolerate severe symptoms in the contralateral knee after the first TKA, the second TKA should be performed as early as possible. If knee joint function is not well recovered after the first TKA, and patients are anxious to undergo the second TKA, surgeons can advise patients to postpone the operation based on these results.

Unicompartmental knee arthroplasty combined with posterior cruciate ligament reconstruction: a case report

BACKGROUND

In this study, we present the unique case of a patient with knee osteoarthritis (OA) of the medial compartment and posterior cruciate ligament (PCL) deficiency who underwent simultaneous medial unicompartmental knee arthroplasty (UKA) and PCL reconstruction.

CASE PRESENTATION

A 49-year-old male patient presented with a 1-year history of pain and instability in the left knee. The patient had previously experienced a trauma-related injury to the PCL of the left knee that was left untreated. Imaging and physical examination confirmed the presence of left medial knee OA along with PCL rupture. To address these issues, the patient underwent UKA combined with PCL reconstruction. The patient's Lysholm score was 47 before surgery and 81 three months after surgery, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was 29 before surgery and 18 three months after surgery, and the International Knee Documentation Committee (IKDC) subjective score was 56.3 before surgery and 74.7 three months after surgery. Six months after surgery, the patient's gait returned to normal, and he was able to jog.

CONCLUSION

This case report presents the first instance of UKA combined with PCL reconstruction and introduces a novel treatment approach for patients suffering from medial knee OA and ligament injury.

Analysis of cartilage loading and injury correlation in knee varus deformity

Knee varus (KV) deformity leads to abnormal forces in the different compartments of the joint cavity and abnormal mechanical loading thus leading to knee osteoarthritis (KOA). This study used computer-aided design to create 3-dimensional simulation models of KOA with varying varus angles to analyze stress distribution within the knee joint cavity using finite element analysis for different varus KOA models and to compare intra-articular loads among these models. Additionally, we developed a cartilage loading model of static KV deformity to correlate with dynamic clinical cases of cartilage injury. Different KV angle models were accurately simulated with computer-aided design, and the KV angles were divided into (0°, 3°, 6°, 9°, 12°, 15°, and 18°) 7 knee models, and then processed with finite element software, and the Von-Mises stress distribution and peak values of the cartilage of the femoral condyles, medial tibial plateau, and lateral plateau were obtained by simulating the human body weight in axial loading while performing the static extension position. Finally, intraoperative endoscopy visualization of cartilage injuries in clinical cases corresponding to KV deformity subgroups was combined to find cartilage loading and injury correlations. With increasing varus angle, there was a significant increase in lower limb mechanical axial inward excursion and peak Von-Mises stress in the medial interstitial compartment. Analysis of patients' clinical data demonstrated a significant correlation between varus deformity angle and cartilage damage in the knee, medial plateau, and patellofemoral intercompartment. Larger varus deformity angles could be associated with higher medial cartilage stress loads and increased cartilage damage in the corresponding peak stress area. When the varus angle exceeds 6°, there is an increased risk of cartilage damage, emphasizing the importance of early surgical correction to prevent further deformity and restore knee function.

What recovery domains are important following a total knee replacement? A qualitative, interview-based study

OBJECTIVES

To explore people's views of recovery from total knee replacement (TKR) and which recovery domains they felt were important.

DESIGN

Semi-structured interviews exploring the views of individuals about to undergo or who have undergone TKR. A constant-comparative approach with thematic analysis was used to identify themes. The process of sampling, collecting data and analysis were continuous and iterative throughout the study, with interviews ceasing once thematic saturation was achieved.

SETTING

Tertiary care centre.

PARTICIPANTS

A purposive sample was used to account for variables including pre, early or late postoperative status.

RESULTS

12 participants were interviewed, 4 who were preoperative, 4 early postoperative and 4 late postoperative. Themes of pain, function, fear of complications, awareness of the artificial knee joint and return to work were identified. Subthemes of balancing acute and chronic pain were identified.

CONCLUSIONS

The results of this interview-based study identify pain and function, in particular mobility, that were universally important to those undergoing TKR. Surgeons should consider exploring these domains when taking informed consent to enhance shared decision-making. Researchers should consider these recovery domains when designing interventional studies.

Total knee arthroplasty following lateral closing-wedge high tibial osteotomy versus primary total knee arthroplasty: a propensity score matching study

BACKGROUND

The disparity in patient-reported outcomes between total knee arthroplasty (TKA) following high tibial osteotomy (HTO) and primary TKA has yet to be fully comprehended. This study aims to compare the patient-reported outcomes, radiological parameters and complication rates between TKA following HTO and primary TKA.

METHODS

Sixty-five patients who underwent TKA following lateral closing-wedge HTO were compared to a matched group of primary TKA at postoperative 6-months and 1-year. Between-group confounders of age, gender, smoking status, Body Mass index, preoperative Numeric Rating Scale (NRS) pain in rest, Knee injury and Osteoarthritis Outcome Score-Physical function Shortform (KOOS-PS), EuroQol five-dimensional (EQ-5D) overall health score, and Oxford Knee Score (OKS) were balanced by propensity score matching. Patient-reported outcome measures were NRS pain in rest, KOOS-PS, EQ-5D overall health score, and OKS. Radiological parameters were femorotibial angle, medial proximal tibial angle, anatomical lateral distal femoral angle, posterior tibial slope, and patellar height assessed by Insall-Salvati ratio. The complication rates of TKA were compared between the two groups. The HTO survival time, the choice of staple removal before or during TKA in patients who underwent TKA following HTO patients, and the rate of patellar resurfacing were assessed. The p value < 0.0125 indicates statistical significance after Bonferroni correction.

RESULTS

After propensity score matching, no significant between-group differences in the patient-reported outcome measures, radiographical parameters and complication rates were found (p > 0.0125). In the TKA following HTO group, with an average HTO survival time of 8.7 years, staples were removed before TKA in 46 patients (71%) and during TKA in 19 patients, and 11 cases (17%) had patella resurfacing. In the primary TKA group, 15 cases (23%) had patella resurfacing.

CONCLUSION

The short-term assessment of TKA following HTO indicates outcomes similar to primary TKA. A previous HTO does not impact the early results of subsequent TKA, suggesting that the previous HTO has minimal influence on TKA outcomes.

LEVEL OF EVIDENCE

III, cohort study.

[Evaluation of the efficacy of medial open wedge high tibial osteotomy combined with anterior cruciate ligament reconstruction in the treatment of varus knee osteoarthritis with anterior cruciate ligament injury]

Objective: To evaluate the efficacy of medial open wedge high tibial osteotomy (MOWHTO) combined with anterior cruciate ligament (ACL) reconstruction in the treatment of varus knee osteoarthritis (OA) with ACL injury. Methods: A follow-up study. The study retrospectively analyzed the patients underwent MOWHTO combined with ACL reconstruction for treatment of varus knee OA with ACL injury in Tianjin Hospital between April 2018 and September 2022. The preoperative and postoperative posterior slope angle (PSA), hip-knee-ankle angle (HKA), visual analog scale (VAS) pain scores, Lysholm score, International Knee Documentation Committee (IKDC) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and Tegner score were compared. The follow-up indicators were recorded at 6 weeks, 3 months and 1 year after operation, and the complications were recorded. Results: The study included 32 patients (23 males, 9 females) with a mean age of (50.7±8.4) years. The mean follow-up time was (21.2±4.8) months. PSA increased from 9.2°±1.8° preoperatively to 11.1°±2.4° postoperatively, and HKA increased from 168.7°±2.2° to 181.5°±2.2° (both P<0.01). The indicators such as VAS score (6.8±1.1 vs 1.8±0.4), Lysholm score (52.6±7.1 vs 82.0±6.4), IKDC score (64.7±6.2 vs 80.3±10.0), WOMAC score (51.8±6.3 vs 81.8±6.5), and Tegner score (1.9±0.6 vs 5.0±1.0) were all improved after the operation (all P<0.01). Complications occurred in 5 patients (15.6%), including hematomas, sensory abnormalities, intermuscular vein thrombosis and correction angle loss. Conclusion: MOWHTO combined with ACL reconstruction is a safe and effective approach for the treatment of varus knee OA with ACL injury.

Metal-backed or all-poly tibial components: which are better for medial unicompartmental knee arthroplasty? A propensity-score-matching retrospective study at the 5-year follow-up

BACKGROUND

This retrospective medium-term follow-up study compares the outcomes of medial fixed-bearing unicompartmental knee arthroplasty (mUKA) using a cemented metal-backed (MB) or an all-polyethylene (AP) tibial component.

MATERIALS AND METHODS

The database of our institution was mined for primary mUKA patients implanted with an MB or an AP tibial component (the MB-UKA and AP-UKA groups, respectively) from 2015 to 2018. We compared patient demographics, patient-reported outcome measures (PROMs), and motion analysis data obtained with the Riablo™ system (CoRehab, Trento, Italy). We conducted propensity-score-matching (PSM) analysis (1:1) using multiple variables.

RESULTS

PSM analysis yielded 77 pairs of MB-UKA and AP-UKA patients. At 5 years, the physical component summary (PCS) score was 52.4 ± 8.3 in MB-UKA and 48.2 ± 8.3 in AP-UKA patients (p < 0.001). The Forgotten Joint Score (FJS-12) was 82.9 ± 18.8 in MB-UKAs and 73.4 ± 22.5 in AP-UKAs (p = 0.015). Tibial pain was reported by 7.8% of the MB-UKA and 35.1% of the AP-UKA patients (p < 0.001). Static postural sway was, respectively, 3.9 ± 2.1 cm and 5.4 ± 2.3 (p = 0.0002), and gait symmetry was, respectively, 92.7% ± 3.7 cm and 90.4% ± 5.4 cm (p = 0.006). Patient satisfaction was 9.2 ± 0.8 in the MB-UKA and 8.3 ± 2.0 in the AP-UKA group (p < 0.003).

CONCLUSIONS

MB-UKA patients experienced significantly better 5-year static sway and gait symmetry outcomes than AP-UKA patients. Although the PROMs of the two groups overlapped, MB-UKA patients had a lower incidence of tibial pain, better FJS-12 and PCS scores, and were more satisfied.

Comparison of Outcomes in Obese Patients after Total Knee Arthroplasty with Neutral or Mild Varus: A Retrospective Study with 8-Year Follow-Up

OBJECTIVES

Residual varus after total knee arthroplasty (TKA) can affect functional outcomes, which may worsen in the presence of obesity. However, no studies were found to compare the outcomes of obese patients involving postoperative residual mild varus or neutral. The aim of this study was to compare postoperative complications and prosthesis survival, and functional outcomes for knees of obese patients with neutral or mild varus after TKA.

METHODS

We retrospectively reviewed 188 consecutive obese patients (body mass index ≥30 kg/m2) at our hospital who underwent TKA due to varus knee osteoarthritis from January 2010 to December 2015. The mechanical hip-knee-ankle axis angle was measured in all patients at admission and discharge. Knee functions were retrospectively assessed based on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society Knee Score (KS-KS), Knee Society Function Score (KS-FS), Forgotten Joint Score (FJS), and range of motion (ROM). Continuous data were compared between knees with neutral or mild varus alignment using analysis of Student's t test or variance or the Kruskal-Wallis test as appropriate. For multiple comparisons of outcomes, we used Bonferroni-Dunn method to adjust p-values. Categorical data were compared using the chi-squared test.

RESULTS

Of the 156 knees in 137 obese patients who completed follow-up for a mean of 8.32 ± 1.47 years, 97 knees were corrected from varus to neutral and 54 knees were kept in mild residual varus. Patients with mild varus knees had significantly WOMAC (8.25 ± 8.637 vs. 14.97 ± 14.193, p = 0.009) and better FJS (86.03 ± 15.607 vs. 70.22 ± 30.031, p = 0.002). The two types of knees did not differ significantly in KS-KS, KS-FS, or ROM. Although one patient with a neutral knee had to undergo revision surgery, there was no significant difference between two groups.

CONCLUSIONS

For obese patients with osteoarthritis, preservation of residual varus alignment after TKA can improve functional outcomes without compromising prosthesis survival.

Editorial Commentary: Meniscal Allograft Transplantation Results in Both Pain Relief and Chondroprotection

Meniscal allograft transplantation (MAT) effectively alleviates symptoms of the meniscus deficiency. Thus, MAT is a widely accepted and recommended treatment for individuals with unicompartmental pain due to meniscus deficiency. Long-term follow-up studies have indicated that MAT yields favorable clinical outcomes, demonstrating high survivorship and low rates of serious complications. In addition, the ability of MAT to function akin to the native meniscus and shield the knee cartilage from osteoarthritis has been a subject of ongoing investigation, and recent direct magnetic resonance imaging evidence shows long-term chondroprotection following MAT. Cartilage lesions worsen during the meniscus deficiency period. Consequently, delaying MAT until patients become more symptomatic may lead to poor outcomes and low graft survivorship due to concomitant cartilage lesions. These findings prompt a reevaluation of the purpose and timing of MAT decisions for meniscectomy patients, suggesting a more proactive approach to recommending MAT, particularly for patients at high risk of postmeniscectomy syndrome and osteoarthritis progression.

Racialized Inequities in Knee Arthroplasty Receipt After Osteoarthritis Diagnosis in the US Military Health System

OBJECTIVE

The goal was to evaluate institutional inequities in the US Military Health System in knee arthroplasty receipt within three years of knee osteoarthritis diagnosis when accounting for other treatments received (eg, physical therapy, medications).

METHODS

In this retrospective observational cohort study, medical record data of patients (n = 29,734) who received a primary osteoarthritis diagnosis in the US Military Health System between January 2016 and January 2020 were analyzed. Data included receipt of physical therapy one year before diagnosis and up to three years after diagnosis, prediagnosis opioid and nonopioid prescription receipt, health-related factors associated with levels of racism, and the primary outcome, knee arthroplasty receipt within three years after diagnosis.

RESULTS

In a generalized additive model with time-varying covariates, Asian and Pacific Islander (incidence rate ratio [IRR] 0.58, 95% confidence interval [CI] 0.45-0.74), Black (IRR 0.52, 95%CI 0.46-0.59), and Latine (IRR 0.66, 95%CI 0.52-0.85) patients experienced racialized inequities in knee arthroplasty receipt, relative to white patients (all P < 0.001).

CONCLUSIONS

In the present sample, Asian and Pacific Islander, Black, and Latine patients were significantly less likely to receive a knee arthroplasty, relative to white patients. Taken together, system-level resources are needed to identify and address mechanisms underlying institutional inequities in knee arthroplasty receipt, such as factors related to systemic and structural, institutional, and personally mediated racism.

Calipered kinematic alignment restored the arithmetic hip-knee-ankle angle, achieved high satisfaction and improved clinical outcomes

PURPOSE

The purpose of this study was to determine whether unrestricted calipered kinematic alignment (KA), coupled with a medial-stabilised (MS) implant system, can reproduce the patient's constitutional alignment as per the arithmetic hip-knee-ankle (aHKA) and improve clinical outcomes.

METHODS

One-hundred and ninety-three patients received total knee arthroplasty by the senior author. To determine whether the constitutional alignment was achieved, the postoperative hip-knee-ankle (HKA) alignment was compared against the aHKA. Range of motion (ROM) was determined preoperative and postoperatively at 6 months and 2 years by measuring the active flexion and extension. Patient-Reported Outcomes Measures (PROMs) including Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score (FJS) and Visual Analogue Scale for Satisfaction were also completed. The Sports and Recreation component of KOOS was used to assess the patient's ability to return to sports and daily activities.

RESULTS

There was a strong correlation between postoperative HKA and aHKA (r = 0.7, p < 0.05). There was a significant improvement in both extension and flexion seen from as early as 6 months postoperatively, with a mean flexion of 123° ± 11° and extension of 1° ± 3° at 2 years. PROMs had significant improvements with a mean score of 42.8 ± 6.0 for the OKS and all KOOS subscales consisting of Symptoms (88.0 ± 11.7), Pain (91.4 ± 11.6), Activities of Daily Living (91.1 ± 12.4), Sports (76.8 ± 22.1) and Quality of Life (83.0 ± 19.1). The FJS had significant improvements from 6 months to 2 years of 19.9 (p < 0.05), with a mean score of 69.2 ± 26.6 at 2 years. Ninety-three percent (180 patients) were classified as 'satisfied' at the 2-year timepoint. The KOOS Sports component was completed by 64% (124 patients), whereby the mean age was younger than the noncompliant patients (67.7 ± 9.4 vs. 71.7 ± 8.2 years).

CONCLUSION

Unrestricted calipered KA can result in an alignment that closely resembles the patient's constitutional alignment, as per the aHKA. This resulted in improved knee ROM and patient satisfaction, as well as assisting younger patients to return to sports and daily activities.

LEVEL OF EVIDENCE

Level IV.

Knee kinematics are not different between asymmetrical and symmetrical tibial baseplates in total knee arthroplasty: A fluoroscopic analysis of step-up and lunge motions

PURPOSE

This clinical fluoroscopy study investigated knee kinematics of two different cemented fixed-bearing, posterior-stabilised (PS) total knee arthroplasty (TKA) designs: an asymmetric tibial component including an asymmetric insert designed to optimise personalised balance and fit and its precursor symmetrical design with symmetric insert.

METHODS

A consecutive series of patients (16 TKAs from each treatment group) participating in a randomised controlled trial comparing TKA migration was included. The exclusion criterion was the use of walking aids. Flat-panel fluoroscopic recordings of step-up and lunge motions were acquired 1-year postoperatively. Medial and lateral contact points (CPs) were determined to calculate CP displacement, femoral axial rotation and pivot position. Using linear mixed-effects modelling techniques, kinematics between TKA designs were compared.

RESULTS

During knee extension between 20° flexion and full extension, the CPs moved anteriorly combined with a small internal femoral rotation (a screw-home mechanism). Whereas CP movement was reversed: femoral rollback, external femoral rotation while flexing the knee between full extension and 20° knee flexion, At larger flexion angles, femoral axial rotation (FAR) occurred around a lateral pivot point both during step-up and lunge. The symmetric design had a 2.3° larger range of FAR compared to the asymmetric design during lunge (p = 0.02). All other kinematics were comparable.

CONCLUSION

Despite the differences in design, this study showed that the asymmetric and symmetric PS TKA designs had mostly comparable knee kinematics during step-up and lunge motions. It is therefore expected that the functionality of the successor TKA design is similar to that of its precursor design.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Changes in Patellar Height and Tibial Posterior Slope after Biplanar High Tibial Osteotomy with Computer-Designed Personalized Surgical Guides: A Retrospective Study

OBJECTIVE

Medial opening-wedge high tibial osteotomy (MOWHTO) is a surgical procedure to treat medial compartment osteoarthritis in the knee with varus deformity. However, factors such as patellar height (PH) and the sagittal plane's posterior tibial slope angle (PTSA) are potentially overlooked. This study investigated the impact of alignment correction angle guided by computer-designed personalized surgical guide plate (PSGP) in MOWHTO on PH and PTSA, offering insights for enhancing surgical techniques.

METHODS

This retrospective study included patients who underwent 3D-printed PSGP-assisted MOWHTO at our institution from March to September 2022. The paired t-tests assessed differences in all preoperative and postoperative measurement parameters. Multivariate linear regression analysis examined correlations between PTSA, CDI (Caton-Deschamps Index), and the alignment correction magnitude. Receiver operating characteristic (ROC) curve analysis determined the threshold of the correction angle, calculating sensitivity, specificity, and area under the curve.

RESULTS

A total of 107 patients were included in our study. The CDI changed from a preoperative mean of 0.97 ± 0.13 (range 0.70-1.34) to a postoperative mean of 0.82 ± 0.13 (range 0.55-1.20). PTSA changed from a preoperative mean of 8.54 ± 2.67 (range 2.19-17.55) to a postoperative mean of 10.54 ± 3.05 (range 4.48-18.05). The t-test revealed statistically significant changes in both values (p < 0.05). A significant alteration in patellar height occurred when the correction angle exceeded 9.39°. Moreover, this paper illustrates a negative correlation between CDI change and the correction angle and preoperative PTSA. Holding other factors constant, each 1-degree increase in the correction angle led to a 0.017 decrease in postoperative CDI, and each 1-degree increase in preoperative PTSA resulted in a 0.008 decrease in postoperative CDI. PTSA change was positively correlated only with the correction angle; for each 1-degree increase in the opening angle, postoperative PTS increased by 0.188, with other factors constant.

CONCLUSION

This study highlights the effectiveness and precision of PSGP-assisted MOWHTO, focusing on the impact of alignment correction on PH and PTSA. These findings support the optimization of PSGP technology, which offers simpler, faster, and safer surgeries with less radiation and bleeding than traditional methods. However, PSGP's one-time use design and the learning curve required for its application are limitations, suggesting areas for further research.

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.

Functional knee phenotypes appear to be more suitable for the Chinese OA population compared with CPAK classification: A study based on 3D CT reconstruction models

PURPOSE

The aim of this study was to investigate the distribution of coronal plane alignment of the knee (CPAK) classification and functional knee phenotypes in a Chinese osteoarthritis (OA) population and to compare different lower limb alignment targets according to the distribution characteristics to find suitable total knee arthroplasty (TKA) bone cut strategies for the Chinese OA patients.

METHODS

The computed tomography (CT) images were retrospectively collected and the three-dimensional (3D) models were reconstructed from 434 Chinese OA patients, including 93 males and 341 females, with a mean age of 66.4 ± 9.3 years. Femoral mechanical angle (FMA), tibial mechanical angle (TMA) and mechanical hip-knee-ankle angle (mHKA) were measured on the 3D models. Arithmetic hip-knee-ankle angle (aHKA) was calculated using FMA plus TMA, and joint line obliquity was calculated as 180 + TMA-FMA. The CPAK according to MacDessi and the functional knee phenotypes according to Hirschmann were performed. In addition, the suitable TKA bone cut strategies were explored according to the phenotypes and based on the characteristics of different alignment targets, such as mechanical alignment, anatomic alignment (AA), kinematic alignment, restricted KA (rKA) and adjusted MA (aMA). Statistical differences were determined using the independent-samples t-test or the two independent-samples Wilcoxon test, with p < 0.05 considered statistically significant.

RESULTS

The Chinese OA population showed a varus alignment tendency (mHKA = 172.1° ± 7.2°), to which the TMA was a major contributor (TMA = 84.7° ± 4.4° vs. FMA = 91.3° ± 3.2°). The mHKA was on average 3.9° more varus than the aHKA. A total of 140 functional knee phenotypes were found and 45.6% were concentrated in VARFMA3°-NEUFMA0° to VARTMA3°-NEUTMA0°. More than 70% of patients had different FMA and TMA phenotypes. There were 92.9% of CPAK distributed in types I to IV, with type I accounting for 53.9%. The FMA phenotypes were less changed if the aMA and rKA were chosen, and the TMA phenotypes were less changed if the AA and rKA were chosen.

CONCLUSION

Compared with the CPAK, the functional knee phenotypes were more suitable for the Chinese OA population with a wide distribution and a varus tendency, and it seemed more appropriate to choose aMA and rKA as TKA alignment targets for resection.

LEVEL OF EVIDENCE

Level Ⅲ.

Functionally aligned total knee arthroplasty: A lateral flexion laxity up to 6 mm is safe!

PURPOSE

Loose flexion gaps are associated with poor functional outcomes and instability in total knee arthroplasty (TKA). The effect of a trapezoidal flexion gap in a functionally aligned TKA remains unknown. The aim of this study was to investigate the effect of a larger lateral flexion gap in a robotic-assisted (RA), functionally aligned (FA) and cruciate-retaining (CR) TKA on clinical outcomes.

METHODS

Data from 527 TKA in 478 patients from 2018 to 2020 were collected. All patients underwent an RA (MAKO, Stryker), FA and CR TKA. Gap measurements were collected intraoperatively. Patient-reported outcome measures (PROMs), pain Visual analogue score (VAS) and range of motion were collected postoperatively. Patients were also asked about the ease of stair ascent and descent and kneeling on a 5-point scale. The minimum follow-up was 2 years. Patients were stratified into three groups based on lateral flexion laxity.

RESULTS

At 2 years postoperatively, the group with a looser gap (3-6 mm) had higher mean PROMs when compared with the group with a gap of 2-3 mm. There were no differences detected in any other outcomes at 2 years. A total of 70.9% of patients in the group with a 3-6 mm gap reported being able to walk down a flight of stairs 'easily', compared with 56.7% in the 2-3 mm group and 54% in the <2 mm group (p = 0.04).

CONCLUSION

The study shows that a loose lateral flexion gap in functionally aligned CR TKA does not adversely affect outcomes in the short term.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Tibia-first, gap-balanced patient-specific alignment restores bony phenotypes and joint line obliquity in a great majority of varus and straight knees and normalises valgus and severe varus deformities

PURPOSE

The present study focuses on testing the capability of a restricted tibia-first, gap-balanced patient-specific alignment technique (PSA) to restore bony morphology and phenotypes.

METHODS

Three-hundred and sixty-seven patients were treated with navigated total knee arthroplasty and tibia-first gap-balanced PSA technique. Boundaries for medial proximal tibial angle were 86°-92°, mechanical lateral distal femoral angle 86°-92°, and hip-knee-ankle angle 175°-183°. Knees were classified by coronal plane alignment of the knee (CPAK), with subsequent analyses comparing pre- and postoperative distributions. Phenotype classification within CPAK groups assessed pre- and postoperative distributions.

RESULTS

Preoperatively, the largest CPAK group was type II (30.8%), followed by type I (20.5%) and type V (17.8%). Postoperatively, type II remained the largest group (39%), followed by type V (30%). All groups with varus/valgus deformities (I, III, IV and VI) became smaller. While in straight legs (II, IV), the CPAK was restored in more than 70%-75%, in varus groups (I, IV) in 40%-50% and in valgus (III and VI) in 5%-18%. The joint line obliquity remained the same in the majority of knees (straight >75%; varus 63%-80%; valgus VI 95%), with the exception of CPAK III (40%). The phenotype analysis showed for straight legs a phenotype restoration of 85%, for varus 94% and for valgus 37%. Joint line convergence angle was reduced significantly in all groups from 1.8°-4.3° preoperatively to 0.6°-1.2° postoperatively.

CONCLUSION

PSA restores bony phenotypes and joint line obliquity in the majority of straight and varus knees, while most of the valgus and extreme varus knees are normalised.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Saw-box osteotomy versus reamer-box osteotomy in posterior stabilized total knee arthroplasty: a retrospective study of an average five year follow-up

PURPOSE

The purpose of this study is to compare the difference of results between two methods of femoral box osteotomy adopted by two designs of posterior stabilized total knee prostheses.

PATIENTS AND METHODS

Retrospective analysis of the results of two groups of patients operated upon using two primary PS TKA systems, PFC Sigma (DePuy Synthes, Johnson and Johnson®) and Genesis II prosthesis (Smith and Nephew®), with an average of five year follow-up was done. Group 1 included 152 knees in 121 patients and group 2 included 122 knees in 111 patients. The average follow-up period in both groups was five years. The box osteotomy method depends on bone saw in group 1, and bone reamer in group 2.

RESULTS

The KSS score of group 2 was better in the first six months postoperatively. Then, no significant differences were seen in the remaining follow-up visits. The risk of periprosthetic fractures was significantly higher in group 1 (p-value 0.040). Survival analysis showed a significantly shorter time for reoperation in group 1 than in group 2 as described by log-rank test, (p < 0.006).

CONCLUSION

The method of box cutting has an impact on the function and longevity of posterior stabilized primary knee implants. The risk of periprosthetic fractures can be reduced by proper patient selection, decreasing the box sizes, and development of more "controlled" box osteotomy instruments.

Mobile medial pivot (lateral slide)-type total knee arthroplasty exhibited different motion patterns between under anaesthesia and weight-bearing condition

PURPOSE

Total knee arthroplasty (TKA), which has medial pivot and mobile-bearing mechanisms, has been developed and clinically used. However, the in vivo dynamic kinematics of the mobile medial pivot-type TKA (MMPTKA) is unclear. This study analysed the in vivo kinematics of MMPTKA in weight-bearing and nonweight-bearing conditions.

METHODS

The study included 10 knees that underwent primary TKA using MMPTKA. After TKA, lateral view radiographs of the knee in full extension, 90° of flexion and passive full flexion were taken under general anaesthesia in the nonweight-bearing condition. At least 6 months postoperatively, knee motion during squatting from a weight-bearing standing position was observed using a flat-panel detector and analysed using the three-dimensional-to-two-dimensional image registration technique.

RESULTS

Under anaesthesia: in passive full flexion, the anteroposterior (AP) locations of the femoral component's medial and lateral distal points were 10.2 and 16.0 mm posterior, and the rotational angles of the femoral component's X-axis (FCX) and insert were 8.1° external rotation and 18.5° internal rotation to full extension, respectively. Squatting: the AP translations of the femoral component's medial and lateral most distal points were 2.2 and 6.4 mm, and the rotational angles of the FCX and insert were 5.7° and 1.6° external rotation, respectively. Significant differences were observed in the AP translation of the femoral component's medial and lateral most distal points and changes in the insert's rotational angle when comparing under anaesthesia and squatting.

CONCLUSIONS

The kinematics of the insert in MMPTKA was significantly influenced by loading and muscle contraction. The femoral component exhibited substantial external rotation and posterior translation under anaesthesia, which may contribute to achieving an optimal range of motion. The insert remained relatively stable during squatting and minimal rotation was observed, indicating good stability. MMPTKA was expected to demonstrate rational kinematics by incorporating mobile and medial pivot mechanisms.

LEVEL OF EVIDENCE

Level IV, prospective biomechanical case series study.

Small change in the arithmetic hip-knee-ankle angle during unicompartmental knee arthroplasty improves early postoperative functional outcomes

INTRODUCTION

The optimal lower-limb alignment after unicompartmental knee arthroplasty (UKA) remains controversial. This study aimed to investigate the optimal lower-limb alignment for functional improvement in the early post-UKA period. We hypothesized that a small change (Δ) in the arithmetic hip-knee-ankle (aHKA) angle during surgery would result in better postoperative knee function.

MATERIALS AND METHODS

This single-centered, retrospective study analyzed 91 patients (91 knees) who underwent UKA from April 2021 and December 2022. Preoperative and postoperative standing whole-leg radiographs were used to evaluate the mechanical HKA angle and aHKA angle. The aHKA angle was calculated from the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). We defined restored aHKA angle as a postoperative aHKA angle within ± 3° of the preoperative aHKA angle. Functional improvement was evaluated using the preoperative and one-year postoperative Knee Society Scoring 2011 (KSS 2011). A multivariate regression analysis was performed to investigate the optimal lower-limb alignment for functional improvement.

RESULT

Postoperative restored aHKA angle (p = 0.020) was the only significant factor for improved KSS 2011 scores. Postoperative restored aHKA angle was obtained in 64 patients (70%). ΔMPTA (p < 0.001) and ΔLDFA (p = 0.037) were significant factors associated with a postoperative restored aHKA angle.

CONCLUSIONS

UKA restores the native knee, including resurfacing constitutional alignment and medial collateral ligament tension. Minimal change in the aHKA angle during UKA improves the functional outcomes of the knee during the early postoperative period, consistent with the minimally invasive surgical concept of UKA.

Impacts of Knee Arthroplasty on Activity Level and Knee Function in Young Patients: A Systematic Review

The annual demand for knee arthroplasty has been steadily rising, particularly in younger patients. The primary objective of this systematic review was to determine the impact of knee arthroplasties on knee function and activity levels in young (≤55 years) patients. A PubMed search from inception (1977) to March 2022 to identify eligible studies produced 640 peer-reviewed studies for consideration. A total of 18 studies including 4,186 knee arthroplasties in 3,200 patients (mean patient age at the time of surgery: 47.4 years, range: 18-55 years) were ultimately included for analysis. Mean final follow-up (FFU) duration was 5.8 years (range: 2-25.1 years). Mean FFU improvement in Knee Society Clinical Score was 48.0 (1,625 knees, range: 20.9-69.0), Knee Society Function Score was 37.4 (1,284 knees, range: 20-65). Mean FFU for the Tegner and Lysholm activity scale was 2.8 (4 studies, 548 knees, range: 0.7-4.2); University of California Los Angeles Physical Activity Questionnaire score was 2.8 (3 studies, 387 knees, range: 1.2-5); lower extremity activity scale was 1.84 (529 knees). The available evidence suggest that young patients typically realize sustained improvements in knee function compared to preoperative levels; however, these improvements do not typically translate into a return to desired activity levels or quality of life, and this patient population should expect a higher and earlier risk for revision than their older counterparts. Further research, including robust registry data, is needed to establish evidence-based indications, expectations, and prognoses for outcomes after knee arthroplasty in young and active patients.

What's important for recovery after a total knee replacement? A systematic review of mixed methods studies

BACKGROUND

Understanding how patients perceive and prioritise various aspects of recovery following total knee replacement, including pain, function and return to activity, will help clinicians in pre-operative consultations by ensuring they effectively address patient concerns and managing their expectations.

AIMS

The aim of this study is to identify aspects of recovery that are important to people after a total knee replacement.

METHODS

Studies were identified from Medline, Embase, PsycInfo, Cochrane Library and Web of Science. This mixed methods review included all original study types (quantitative, qualitative, discrete choice experiments and mixed methods design). Reviews and non-peer-reviewed publications were excluded. Studies with participants (age ≥ 18 years) who had a primary TKR for osteoarthritis were included. Studies of people with unicompartmental knee, patella-femoral or revision knee replacement were excluded. Recovery attributes were extracted from individual papers and grouped into recovery themes.

RESULTS

A total of 23 studies with 8404 participants and 18 recovery themes were developed. The most frequently identified overarching theme was pain, followed by activities of daily living, mobility (walking), recreational activities, specific functional movements of the knee, use of walking aids, sexual activity and range of motion of the knee. Medical complications were an infrequently reported theme, however, was deemed to be high importance.

CONCLUSIONS

Reducing pain, returning of activities and daily living and mobility are the three most frequently reported recovery domains for people after TKR. Clinicians should be aware of recovery themes, to ensure they are explored sufficiently when consenting for a TKR. Future research should aim to determine the relative importance of these attributes compared to each other. Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021253699.

Severity Of Radiographic Osteoarthritis: Association with Improved Patient Reported Outcomes Following Knee Arthroplasty

INTRODUCTION

The Kellgren and Lawrence (KL) classification for knee osteoarthritis estimates disease severity. Its utility in predicting patient-reported outcomes (PROs) after primary total knee arthroplasty (pTKA) has been suggested. We hypothesized that patients who had higher preoperative KL grades would demonstrate greater improvements in PROs after pTKA.

METHODS

This was a retrospective review of patients who underwent pTKA between 2016 and 2021. Two observers graded preoperative radiographs (KL1/2, KL3, and KL4). Knee Injury and Osteoarthritis Outcome Score (KOOS) for activities of daily living (KOOS-ADL) and pain (KOOS-Pain) were collected at preoperative and 12-month postoperative visits. Changes in KOOS-ADL (ΔADL) and changes in KOOS-Pain (ΔPain) scores were compared from the preoperative to 12-month postoperative mark across different groups, with the minimal clinically important difference (MCID) for both ΔADL (MCID-ADL) and ΔPain (MCID-Pain) also being calculated. A P-value of < 0.05 was considered statistically significant.

RESULTS

A total of 1651 patients were included in the study. The KL3 and KL4 groups exhibited significantly higher ΔADL scores and ΔPain scores compared with the KL1/2 group (P < 0.01). Patients who had KL3 and KL4 were 1.42 (P = 0.03) and 1.88 (P < 0.01) times, respectively, more likely to achieve MCID-ADL compared with those who had KL1/2. Furthermore, patients who had a KL4 were 1.92 times (P < 0.01) more likely to reach MCID-Pain compared with those who had KL1/2.

CONCLUSIONS

This study determined that patients who had higher preoperative KL grades experienced markedly greater improvements in KOOS-ADL and KOOS-Pain scores than those who had lower KL grades. These findings offer surgeons an objective tool when counseling patients on expected outcomes after pTKA.

Influence of Distal Reference Point of the Tibial Mechanical Axis on the Ankle and Hindlimb Alignment Change after Total Knee Arthroplasty

The alignment philosophy in total knee arthroplasty (TKA) has tended to shift from the gold standard of mechanically aligned technique to personalized alignment, such as the kinematically aligned (KA) technique. However, the influences of different surgical techniques on lower limb alignment relative to the ground are not fully investigated. This study investigated the influence of the ankle and hindlimb alignment change after mechanically aligned TKA and KA-TKA. The varus osteoarthritic patients who underwent TKAs were divided into a mechanically aligned TKA group (group M, n = 50) and a KA-TKA group (group K, n = 50). Radiographic parameters (hip-knee-calcaneus [HKC] angle, hip-knee-ankle [HKA] angle, talar tilt angle [TTA], and tibiocalcaneal angle [TCA]) were investigated using full-length standing radiographs. The deviation angle (ΔTA; angle between the tibial mechanical axis [TMA] and the ground tibial mechanical axis [gTMA]) and the change of ΔTA (cΔTA) were also assessed. These parameters were compared between the two groups, along with the correlation between the preoperative HKA angle and other parameters. ΔTA, TTA, and TCA showed no differences between the groups pre- and postoperatively, and no significant changes were observed postoperatively. The preoperative HKA angle showed a significant negative correlation with cΔTA in both groups (group M: r = -0.33, p = 0.02; group K: r = -0.29, p = 0.04) although no correlation was observed the with preoperative TTA and TCA. Despite no change in ΔTA after surgery, the preoperative varus deformity was associated with a change in the deviation between gTMA and TMA after surgery. A severely varus knee may be inappropriate for ground KA-TKA.

What effect does preoperative flexion contracture have on the component angles in unicompartmental knee arthroplasty?

PURPOSE

The indication for unicompartmental knee arthroplasty (UKA) has been extended to cases with some degree of preoperative knee flexion contracture recently. The purpose of this study was to clarify the effect of flexion contracture on component angles.

MATERIALS AND METHODS

Thirty-five fixed-bearing UKAs using the spacer block technique with preoperative flexion contracture (Group FC) and 35 UKAs using the same technique without preoperative flexion contracture (Group NC) were included. Using radiographs, the coronal femoral component angle, coronal tibial component angle, sagittal femoral component angle, and sagittal tibial component angle were determined. Also, extension and flexion angles of the knee as well as coronal Hip-Knee-Ankle (HKA) angles in long-leg standing radiographs were measured. The data about the thickness of the selected insert were also collected. The above results were compared between the two groups.

RESULTS

The femoral component tended to be placed in a more varus and flexed position in Group FC, while no significant difference was found about the tibial component angles. While there was no significant difference in pre- and postoperative knee flexion angles between the two groups, flexion contracture remained postoperatively in Group FC. Preoperative HKA angle was greater in Group FC while the difference was no longer significant postoperatively. Regarding the thickness of the selected insert, thicker inserts tended to be used in Group FC.

CONCLUSIONS

In fixed-bearing UKA with the spacer block technique, the femoral component tended to be placed in a flexed and varus position in the knees with preoperative flexion contracture.

Superiority of kinematic alignment over mechanical alignment in total knee arthroplasty during medium- to long-term follow-up: A meta-analysis and trial sequential analysis

PURPOSE

To compare and determine the reliability and conclusiveness of the medium- and long-term efficacy in terms of patient-reported outcome measures and the risk of revisions or reoperations (RRRs) of kinematic alignment (KA) and mechanical alignment (MA) in total knee arthroplasty.

METHODS

A comprehensive search was conducted in Medline, EMBASE, Web of Science and Cochrane Database Library to identify relevant literature. Only randomised clinical trials (RCTs) published before July 2023 were included. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), Forgotten Joint Score (FJS) and RRR were compared. Additionally, OKS and RRR were subjected to a trial sequential analysis.

RESULTS

Seven RCTs involving 572 knees were identified. The pooled analysis of the included studies demonstrated that KA showed better medium-term WOMAC and OKS (mean difference [MD] = -6.3, 95% confidence interval [CI]: -9.52 to -2.99, p < 0.05 and MD = 1.1, 95% CI: 0.05-2.15, p < 0.05), respectively), but no significant differences were observed in the long-term follow-up (MD = 2.1, 95% CI: -3.21 to 7.31, not significant [n.s.] and MD = 0.01, 95% CI: -2.43 to 2.46, n.s., respectively). FJS (standardised MD = -0.03, 95% CI: -0.25 to 0.19, n.s.) and RRR (risk ratio = 1.0, 95% CI: 0.57 to 1.74, n.s.) showed no significant intergroup differences (n.s.). The evidence quality ranged from moderate to high, and the trial sequential analysis indicated the need for additional high-quality RCTs to draw more conclusive results.

CONCLUSIONS

KA showed better medium-term WOMAC and OKS, while KA and MA had similar FJS without increasing the RRR in medium- and long-term follow-up. Further research is needed for more conclusive results.

LEVEL OF EVIDENCE

Level II (meta-analyses).

Long-term results (after a mean 11.3years, and up to 22years, of follow-up) of the Legacy Constrained Condylar Knee (LCCK™) in primary total knee arthroplasty

INTRODUCTION

The use of a sliding prosthesis in total knee arthroplasty (TKA) with increased stress is an intermediate solution in primary surgery, between posteriorly stabilized prostheses and hinged prostheses, in cases of ligamentous laxity and/or loss of bone substance. Favorable results have been reported in the medium term but to our knowledge, this type of prosthesis has not been evaluated in Europe beyond 10 years of follow-up. We therefore conducted a retrospective study in order to carry out: 1) the study of the survival of the Legacy Constrained Condylar Knee (LCCK™) prosthesis in primary surgery, 2) the analysis of complications, functional scores and radiographic data, 3) the analysis of the link between the diaphyseal filling rate and prosthetic loosening.

HYPOTHESIS

The LCCK™ sliding prosthesis with increased constraint has equivalent long-term survival and clinical results to standard posteriorly stabilized TKA and superior to hinged TKA.

MATERIAL AND METHOD

A retrospective series of 141 LCCK™ implanted in 134 patients between 1997 and 2010 was analyzed. Survival was assessed with censoring through an evaluation of partial or total revision of the implants. The functional results were evaluated using the IKS and Oxford 12 scores. Data regarding the Canal Fill Ratio (CFR) and the presence of pathological periprosthetic lines were also collected.

RESULTS

The average follow-up was 11.3±5.3years with a maximum follow-up of 22.7years. Survival at 20years was 90.8% [95% CI: 83.7-95.7]. The rate of early complications was 13.5% (19/141), predominantly comprised of venous thrombosis (6/141), hematomas (3/141 including two requiring surgical drainage), stiffness (3/141) and early infections (3/141). The rate of late complications was 17% (24/141), led by stiffness (4.4%; 6/141), infections (2.9%; 4/141) and hardware failure (2. 2%; 3/141). Ten of the 141 patients (7.1%) had LCCK failure, including 3 (2.1%) for stiffness, 3 (2.1%) for hardware failure, 2 (1.4%) for infection, 1 (0.7%) for laxity and 1 (0.7%) for a periprosthetic fracture. No aseptic loosening was found. The total IKS score went from 65 [0-116] to 143 [79-200] at follow-up, the IKS knee score went from 30 [0-66] to 85 [44-100], and the IKS function score went from 35 [0-70] to 57 [0-100]. The Oxford score went from 14 [2-25] to 34 [15-48] at follow-up. Only two patients (1.4%) presented with a partial periprosthetic line. The tibial CFR was 0.81 and the femoral CFR was 0.76. The influence of the CFR could not be analyzed due to the absence of loosening.

DISCUSSION

The LCCK™ prosthesis in primary surgery has good medium-term survival, a significant improvement in functional scores and a complication rate comparable to posteriorly stabilized prostheses. The complication rate is lower than that of hinged prostheses.

LEVEL OF EVIDENCE

IV; single-center retrospective study.

International Knee Documentation Committee Radiographic Knee Joint Grading More Reliable Than Kellgren-Lawrence Grading and Other Grading Systems

Kellgren-Lawrence grading appears to have become the de facto standard for reporting radiographic degeneration of knees, yet the much later-introduced and knee-specific International Knee Documentation Committee system has repeatedly been shown to have higher reliability. Although International Knee Documentation Committee radiographic grading does have limitations-especially in cases of severe gonarthrosis-it appears to be the most reliable current system suitable for the purposes of arthroscopic knee surgeons, and it was designed to encompass all 3 knee compartments. Posterior-anterior weight-bearing radiographs taken at approximately 45° of knee flexion have repeatedly been shown to be more sensitive for revealing tibiofemoral degeneration than standard anterior-posterior weight-bearing views at or near full extension.

Circulating Copper Is Associated with Inflammatory Biomarkers in Greek Older Adults with Osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis, that causes a significant decrease in the quality of life of the afflicted and constitutes a great burden for the socioeconomic system. Trace elements and heavy metals are implicated in the pathophysiology of OA, exacerbating inflammatory and oxidative stress responses. The aim of this cross-sectional study was to quantify metals in plasma samples of Greek OA patients and explore their link with disease related parameters, health status or quality of life, as well as epigenetic OA markers. This is the first study on plasma metal levels in Greek knee OA patients. To achieve precision in plasma metal and miRNA measurements, high-quality samples were selected from a subset of 34 participants (NCT04783792). Demographic, quality of life, clinical, biochemical, inflammation, oxidative stress, and anthropometric parameters, as well as microRNA levels were assessed. Significant correlations were found between circulating metals with OA related parameters or with measured microRNAs. Also, significant positive associations between plasma copper (Cu) levels and CRP (p = 0.033) or IL-6 (p = 0.001) occurred when adjusting for age, gender, BMI, physical activity level, smoking, disease severity, total arthroplasty, and dietary intake of the respective metal. Cu's role in OA is bidirectional, and this study confirms the findings that in OA, Cu is positively associated with inflammation. Such relationships between lifestyle, environment and OA enhance our understanding and encourage further study on metals related to OA inflammation.