Knee Arthroplasty Research Articles

No Difference in Postoperative Complications Between Simultaneous and Staged, Bilateral Unicompartmental Knee Arthroplasty.

Background The optimal timing of contralateral surgery following unicompartmental knee arthroplasty (UKA) remains unknown. Therefore, the objective of this study was to examine the differences in postoperative complications in patients undergoing unilateral, simultaneous and staged bilateral UKA. Methods The PearlDiver administrative claims database was queried for patients undergoing UKA between 2015-2020. Patients undergoing unilateral UKA were matched in a 1:1 fashion based on age, gender, Elixhauser Comorbidity Index (ECI), obesity, diabetes and smoking status to patients undergoing simultaneous bilateral UKA, bilateral UKA staged 1-90 days and bilateral UKA staged 91-365 days. Univariate and multivariate analyses were performed to examine the impact of timing of bilateral procedures on 90-day postoperative complications relative to patients who underwent unilateral UKA. Outcomes were considered significant at p<0.05. Results A total of 9,638 patients undergoing UKA were included in the final analysis, of which 5,672 (58.9%) were unilateral, 396 (4.1%) were simultaneous bilateral, 1,496 (15.5%) were bilateral staged between 1-90 days and 2,074 (21.5%) were bilateral staged between 91-365 days. Univariate analysis identified no significant differences in complications between matched groups except for an increased incidence of wound dehiscence amongst patients who underwent simultaneous bilateral UKA (2.1% vs. 0.0%, p=0.040) compared to unilateral UKA. However, multivariate analysis demonstrated that simultaneous or staged bilateral UKA at either time point did not increase the risk of any postoperative complication relative to unilateral surgery. Conclusion Bilateral UKA can be performed simultaneously or in a staged fashion without increasing the risk of 90-day complications relative to unilateral UKA.

Study of neuromuscular activity in preparation for revision knee arthroplasty

The results of an electromyographic study of 13 patients, aged 50–87 years, with aseptic instability of the components of a knee joint endoprosthesis at the stage of preparation for revision arthroplasty, who were treated at the Republican Scientific and Practical Center of Trauma tology and Orthopedics in the period from 2013 to 2020, were analyzed. To assess the orthopedic status, we used: clinical examination, radiography of the knee joint in 2 standard and axial projections, topogram and CT scan. lectrophysiological studies provide important information for elucidating the etiopathogenesis of knee joint endoprosthesis instability. One of the causes of instability may be an imbalance in the activity of the flexor and extensor muscles that develops during walking, subsequently leading to periprosthetic osteolysis, which occurs as a response to the formation of wear and tear products of the components of the endoprosthesis.

Using at least 20% medial unicompartmental knee arthroplasty is associated with improved patient-reported outcome measures across all knee arthroplasty patients.

To investigate the impact of orthopaedic surgeons' arthroplasty distributions on patient-reported outcome measures (PROMs) following knee arthroplasty, thus addressing the gap in knowledge regarding the optimal distribution of arthroplasties. 2256 knee arthroplasties were included (total knee arthroplasty [TKA] or unicompartmental knee arthroplasty [UKA]). All were conducted at a single centre between August 2016 and August 2022 with a minimum of 1-year follow-up. The Oxford Knee Score (OKS), the Forgotten Joint Score (FJS) and the Activity and Participation Questionnaire (APQ) were assessed preoperatively, and at 3 and 12 months postoperatively. Patients were categorized based on the surgeons' yearly surgeries: (1) TKA only, (2) TKA+ <20% medial UKA, (3) TKA+ ≥20% medial UKA and (4) TKA+ ≥20% medial UKA + lateral UKA + patellofemoral UKA. Linear regression models adjusted for demographic variables and preoperative PROM scores were used to estimate changes in mean PROM scores. Group 4 showed significantly higher improvements in PROM scores at 3 and 12 months compared to Group 1. In the 12-month adjusted analysis, Group 4 had 1.9 points (95% confidence interval [CI]: 1.0-2.8) higher OKS-, 7.0 points (95% CI: 3.9-10.2) higher FJS- and 8.3 points (95% CI: 4.8-11.8) higher APQ-change than Group 1. There were no significant differences between Groups 1 and 2, nor any clinically relevant differences between Groups 3 and 4. Additionally, the percentage of patients who achieved excellent OKS (>41) was significantly higher in Groups 3 + 4 compared to Groups 1 + 2 (p < 0.001). Despite limitations, the findings of this study suggest that utilizing ≥20% medial UKA leads to greater postoperative improvements in PROM across all treated knee arthroplasty patients. Level III.

A Restriction Boundary-Based Coronal Plane Alignment of the Knee (CPAK) Classification for Restricted Kinematic Alignment Total Knee Arthroplasty

A Restriction Boundary-Based Coronal Plane Alignment of the Knee (CPAK) Classification for Restricted Kinematic Alignment Total Knee Arthroplasty

Perioperative and frailty outcomes after total knee arthroplasty: a retrospective cohort study.

Total knee arthroplasty (TKA) is a common procedure with an increasing demand, especially among the elderly. Frailty is known to be associated with adverse perioperative outcomes in the older population. In this article, we aimed to understand the associations of preoperative frailty status and comorbid conditions in relation to their clinical and healthcare outcomes after TKA, and to describe the perioperative factors leading to improvement in a patient's frailty status after TKA. This is a retrospective cohort study, and the outcomes were assessed over 2 years. Frailty is defined by the Clinical Frailty Score. A total of 96 patient records were assessed, of which 13 (13.5%) patients were robust and 83 (86.5%) patients were prefrail or frail. Two years after TKA, the number of robust patients increased to 58 (61.7%) patients, showing a reversal of frailty in 48.2% of patients. Total knee arthroplasty in prefrail and frail patients is a safe procedure that leads to improvement of frailty status, with an increase in the proportion of patients becoming robust within 2 years after the operation.

Utilization of Rehabilitation Services and Rehabilitation-Related Patient Satisfaction Following Total Knee Arthroplasty—Results of the Prospective FInGK Study

(1) Background: This study aims to examine rehabilitation service utilization among total knee arthroplasty (TKA) subjects and the influencing factors associated with rehabilitation-related satisfaction. (2) Methods: The FInGK study was a single-center prospective cohort study. Patients (≥18 years) undergoing primary or revision TKA in a German university hospital were consecutively recruited between December 2019–May 2021. The subjects filled in a questionnaire one day before surgery (t0) and at two (t1) and 12 (t2) months postoperatively. Multivariable logistic regression was conducted to determine the variables associated with the subjects’ rehabilitation-related satisfaction. (3) Results: A total of 236 out of 241 (97.9%) subjects participated in t1 (59.3% female; mean age: 68.2 years). Overall, 94.7% underwent post-TKA rehabilitation measures, with inpatient rehabilitation being the predominant choice (85.4%). In total, 77.6% of those with rehabilitation were satisfied or very satisfied with their rehabilitation in general. Multivariable logistic regression showed that female sex (OR 3.42; CI 1.73–6.75) and satisfaction with the surgery in general after two months (OR 4.50; CI 1.96–10.33) were associated with the subjects’ rehabilitation-related satisfaction. (4) Conclusions: We found a high utilization of rehabilitation services following TKA and a high rehabilitation-related satisfaction. In international comparison, the utilization of inpatient rehabilitation services was very high. Future research should investigate the effective components for rehabilitation-related satisfaction in both in- and outpatient TKA rehabilitation.

Successful 24-hour discharge for total knee arthroplasty: importance of timing of surgery and physiotherapy in enhanced recovery after surgery protocol.

The current literature is mixed on which patient factors, if any, predict the rate of successful discharge within 24 h of enhanced recovery after surgery (ERAS) total knee arthroplasty (TKA). This study aimed to investigate the influence of timing of surgery and physiotherapy on the rate of successful 24-h discharge. All 342 patients who underwent ERAS day surgery TKA from August 2020 to July 2021 were followed up prospectively. Patient characteristics and postoperative outcomes, such as number of physiotherapy sessions required before clearance for home, time taken after surgery to ambulate >10 m and length of stay (LOS), were recorded. Patients were grouped based on surgical end time (morning/afternoon/ evening) and time of physiotherapy review (morning/afternoon/evening/morning after). Patients successfully passed ERAS day surgery protocol if they were discharged within 24 h. With regard to the timing of operation, the morning group had the shortest LOS (P = 0.001) and a higher ERAS day surgery pass rate than the afternoon group (P = 0.016). With regard to the timing of physiotherapy, the afternoon group took the shortest time to ambulate >10 m (P < 0.001), had the shortest LOS (P < 0.001) and had a higher ERAS day surgery pass rate as compared to the morning after the operation group (P = 0.005). Patients who ended their operations in the morning and received physiotherapy review in the same afternoon were the most likely to be discharged within 24 h due to early ambulation and adequate time for spinal anaesthesia to wear off.

Elevated Netrin-4 Expression and Its Action in Infrapatellar Fat Pad

Knee osteoarthritis (KOA) is a degenerative joint disease characterized by inflammation and cartilage degradation. The infrapatellar fat pad (IFP), located beneath the patella within the knee joint, serves as a key anatomical structure involved in cushioning and supporting the knee. It is also an active endocrine organ that secretes various bioactive substances, potentially influencing the local inflammatory environment and contributing to KOA pathogenesis. Netrin-4 (NTN4), a protein primarily known for its role in neuronal guidance, has been implicated in various non-neuronal functions, including inflammatory processes and tissue remodeling. This study aims to explore the involvement of NTN4 in KOA, focusing on its expression in the IFP and its potential impact on disease progression. This study involved 82 patients with radiographically confirmed KOA undergoing total knee arthroplasty (TKA). The correlation between NTN4 expression and OA pathology, including Kellgren–Lawrence (K/L) grades, was investigated. NTN4-expressing cells were identified in the stromal vascular fraction, including fibroblastic, hematopoietic, and endothelial cells of the IFP. To elucidate the molecular effects of NTN4, RNA sequencing (RNA-seq) was performed on fibroblastic cells treated with recombinant NTN4. Subsequent quantitative PCR (qPCR) was used to validate the RNA-seq findings. NTN4 expression was significantly elevated in the IFP of patients with advanced KOA (K/L grades 3 and 4) compared to those with early-stage disease (K/L grade 2). Higher NTN4 expression was found in fibroblastic cells, and RNA-seq analysis revealed upregulation of genes associated with pro-inflammatory pathways, including IL-17 and TNF-α signaling, and matrix degradation. Notably, genes including IL6, MMP1, CXCL1, and CXCL8 were significantly elevated, as confirmed by qPCR, indicating NTN4’s role in promoting an inflammatory and catabolic environment. Our findings suggest that NTN4 plays a significant role in the pathogenesis of KOA by promoting inflammation and matrix degradation within the IFP. Although NTN4 expression was not directly correlated with clinical symptoms, its elevated expression in fibroblastic cells and influence on inflammatory and degradative pathways suggest a potential mechanism for exacerbating joint damage. Targeting NTN4 could offer a novel therapeutic approach to mitigating inflammation and slowing disease progression in KOA, ultimately improving patient outcomes. Further research is needed to clarify NTN4’s specific roles and therapeutic potential in OA management.

The Histopathological Examination of the Degeneration of Menisci in Osteoarthritic Knees Using an Adapted Bonar Score: Does Osteoarthritis Equally Influence the Lateral and Medial Menisci?

This study aimed to investigate the degeneration of the meniscal tissue in osteoarthritic knees and to adapt the Bonar score and its modifications to develop a microscopic examination. This study included consecutive patients who underwent total knee arthroplasty for symptomatic end-stage gonarthrosis. During the surgery, the menisci were completely dissected to preserve their original shapes. The samples were prepared using the hematoxylin and eosin (H&amp;E) staining method and the Alcian blue protocol and were examined under light microscopy. The extent of histopathological changes was assessed based on the classical Bonar score assumptions. Additionally, in the second step of the examination, menisci remnants were evaluated using the modified Bonar score developed by Zabrzyński et al. The study involved 44 patients, from whom 83 samples of knee menisci were obtained. Histological examination of the meniscal specimens under a light microscope revealed tissue degeneration in all cases, in both the medial and lateral menisci. The mean classical Bonar score was 8.3571 and the mean modified Bonar score was 6.9398. There were no statistically significant differences in classical Bonar score assessment between medial and lateral menisci (p = 0.3014). There were no statistically significant differences in the modified-Bonar score assessment between medial and lateral menisci (p = 0.3620). We show that both menisci are implicated in the degenerative process, with high scores in the Bonar system, regardless of knee axial deformity. The Bonar score, along with its modifications, can be readily employed in the microscopic assessment of meniscus pathology.

Combined saphenous (adductor canal) nerve block and sacral erector spinae plane block for total knee arthroplasty pain.

Combined saphenous (adductor canal) nerve block and sacral erector spinae plane block for total knee arthroplasty pain.

Five- and ten-year follow-up of medial unicompartmental knee arthroplasties in obese and non-obese patients.

The aim of this study was to determine whether obesity had a detrimental effect on the long-term performance and survival of medial unicompartmental knee arthroplasties (UKAs). This study reviewed prospectively collected functional outcome scores and revision rates of all medial UKA patients with recorded BMI performed in Christchurch, New Zealand, from January 2011 to September 2021. Patient-reported outcome measures (PROMs) were the primary outcome of this study, with all-cause revision rate analyzed as a secondary outcome. PROMs were taken preoperatively, at six months, one year, five years, and ten years postoperatively. There were 873 patients who had functional scores recorded at five years and 164 patients had scores recorded at ten years. Further sub-group analysis was performed based on the patient's BMI. Revision data were available through the New Zealand Joint Registry for 2,323 UKAs performed during this time period. Obese patients (BMI > 30 kg/m2) were 3.1 years younger than non-obese patients (BMI < 30 kg/m2) at the time of surgery (mean age of obese patients 65.5 years (SD 9.7) and mean age of non-obese patients 68.6 years (SD 10.1)). Preoperatively, obese patients tended to have significantly lower functional scores than non-obese patients, which continued at five and ten years postoperatively. At these timepoints, obese patients had significantly lower scores for most PROMs measured compared to non-obese patients. However, there was no significant difference in the improvement of any of these scores after surgery between obese and non-obese patients. There was no significant difference in revision rates between obese and non-obese patients at any time. All-cause revision rate for obese patients was 0.73 per 100 observed component years compared to 0.67 in non-obese patients at ten years. There was also no significant difference in the aseptic loosening rate between groups. Our study supports the use of UKAs in obese patients, with similar benefit and survival compared to non-obese patients at ten years.

Economic burden of knee joint replacement in Iran

BackgroundThe knee is the most commonly afflicted weight-bearing joint. Osteoarthritis of the knee is regarded as one of the most commonly diagnosed causes of disability in the elderly. Knee joint replacement can be regarded as a final solution for Osteoarthritis of the knee in which the joint is worn out, accompanied by clinical symptoms such as pain, deformity, and limited movement.Aimthis study sought to estimate the economic burden of knee joint replacement procedures carried out in Iran.MethodThis cross-sectional descriptive study utilized the Incidence-based approach to assess the economic burden of knee joint replacement surgeries conducted in Iran during 2022, estimating the costs of the disease from a societal perspective. The sampling method employed was random sampling, and the sample size consisted of 300 patients. Direct costs were calculated employing the top-down approach, while indirect costs were estimated using the human capital approach. Microsoft Excel was employed for data analysis.ResultThe average direct medical costs of the knee replacement procedure per patient were $10,076.87 and $13,099.93 in the public and private sectors, respectively. The average direct non-medical costs of knee joint replacement surgery are $1123.64, with companion costs constituting most of the direct non-medical costs. Finally, the economic burden of the knee joint replacement surgery was estimated at $67340417.28.ConclusionDespite insurance coverage, knee joint replacement surgery in Iran incurs substantial costs. With the anticipated rise in the elderly population, the frequency of these procedures is expected to increase, amplifying the economic burden on the Iranian public.

Effect of lower-limb isokinetic muscle strengthening on knee function and joint contact force in knee osteoarthritis patients awaiting total knee arthroplasty: study protocol for a randomized controlled trial.

Knee osteoarthritis (OA) is a common and serious joint disease and patients mainly suffer from knee pain and dysfunction, significantly impacting their quality of life and daily activities. Non-pharmacological treatments and total knee arthroplasty (TKA) are the two major treatments for knee OA. TKA is the primary treatment for severe knee OA patients, however, the postoperative rehabilitation results are not entirely satisfactory. To enhance postoperative rehabilitation outcomes, preoperative lower-limb muscle strengthening has aroused attention and demonstrated significant results on functional recovery after TKA. Specifically, isokinetic muscle strengthening (IMS) has been highly anticipated as an efficient training method. Nevertheless, its effects in perioperative and long-term periods of TKA require further investigation. This study aims to evaluate the impact of preoperative lower-limb IMS during the 4weeks before TKA on the perioperative and postoperative outcomes, with particular attention on knee function, pain, and inflammatory response. In this study, 104 patients awaiting TKA will be randomized to 2 groups: the IMS and health education groups. All patients will be evaluated at baseline, post-intervention, discharge day, and postoperative day 14, with follow-up assessments at 6weeks, 3, 6, and 12months after discharge. The primary outcome will be the Knee Injury and Osteoarthritis Outcome Score 3months after TKA and the medial-to-lateral knee contact force ratio. The secondary outcomes will be changes in lower-limb muscle strength, knee pain, inflammation response, active range of motion, performance-based function (5-times Sit-to-Stand Test, Time Up-and-Go Test, 3m walking speed), Berg Balance Scale, and surgical need. Lower-limb IMS can improve muscle strength, pain, and function for early knee OA patients. However, the effects of different doses of IMS on perioperative and postoperative knee pain, inflammation response, and function after TKA are inconclusive. This study will provide high-quality evidence to assess the efficacy of IMS in end-stage patients who will undergo TKA. Understanding IMS in end-stage knee OA patients will help guide future surgical management for this population. Trial Registration Chinese Clinical Trial Registry ChiCTR2400088136.

Implant design influences the joint-specific outcome after total knee arthroplasty.

The aims were to assess whether joint-specific outcome after total knee arthroplasty (TKA) was influenced by implant design over a 12-year follow-up period, and whether patient-related factors were associated with loss to follow-up and mortality risk. Long-term follow-up of a randomized controlled trial was undertaken. A total of 212 patients were allocated a Triathlon or a Kinemax TKA. Patients were assessed preoperatively, and one, three, eight, and 12 years postoperatively using the Oxford Knee Score (OKS). Reasons for patient lost to follow-up, mortality, and revision were recorded. A total of 94 patients completed 12-year functional follow-up (62 females, mean age 66 years (43 to 82) at index surgery). There was a clinically significantly greater improvement in the OKS at one year (mean difference (MD) 3.0 (95% CI 0.4 to 5.7); p = 0.027) and three years (MD 4.7 (95% CI 1.9 to 7.5); p = 0.001) for the Triathlon group, but no differences were observed at eight (p = 0.331) or 12 years' (p = 0.181) follow-up. When assessing the OKS in the patients surviving to 12 years, the Triathlon group had a clinically significantly greater improvement in the OKS (marginal mean 3.8 (95% CI 0.2 to 7.4); p = 0.040). Loss to functional follow-up (53%, n = 109/204) was independently associated with older age (p = 0.001). Patient mortality was the major reason (56.4%, n = 62/110) for loss to follow-up. Older age (p < 0.001) and worse preoperative OKS (p = 0.043) were independently associated with increased mortality risk. An age at time of surgery of ≥ 72 years was 75% sensitive and 74% specific for predicting mortality with an area under the curve of 78.1% (95% CI 70.9 to 85.3; p < 0.001). The Triathlon TKA was associated with clinically meaningful greater improvement in knee-specific outcome when compared to the Kinemax TKA. Loss to follow-up at 12 years was a limitation, and studies planning longer-term functional assessment could limit their cohort to patients aged under 72 years.

Will Mobile-Bearing Total Knee Arthroplasty Be Lost to History? A Comparative Study of Long-Term Follow-Up.

Mobile-bearing (MB) total knee arthroplasty (TKA) implants were introduced as an alternative to fixed-bearing (FB) implants because of their theoretical advantages related to femorotibial rotational mismatch. The purpose of this study is to compare the clinical and radiologic outcomes of MB and FB TKA after approximately 13 years of follow-up. We compared the results of 88 patients with a mean age of 66 years who had received a rotating platform MB implant or a FB implant. The mean follow-up was 13.6 years. The patients were assessed clinically (VAS, ROM, KSS, WOMAC scores) and radiographically before and 13 years after operation. There were no statistically significant differences between the FB and MB groups in terms of clinical outcomes and radiological outcomes (p > 0.05 for all). Although the incidence of complications was higher in the MB group, the findings were not statistically significant compared to the FB group (p > 0.05 for all). Although there were no significant differences in the clinical and radiologic outcomes between the FB and MB groups, the possible higher risk of osteolysis or aseptic loosening in the MB group could be an important clinical implication when selecting the TKA implant.

THE RELATIONSHIP OF COVID-19 FEAR WITH PREOPERATIVE ANXIETY AND POSTOPERATIVE ANALGESIC REQUIREMENT IN TOTAL HIP AND KNEE ARTHROPLASTY PATIENTS

It was conducted to determine the relationship between fear of Covid-19 and preoperative anxiety and postoperative analgesic requirement in total hip and knee arthroplasty patients. This descriptive study was conducted with 331 patients scheduled for arthroplasty who were hospitalized in the orthopedic clinic of a hospital in eastern Turkey between March 2022-2023. Fear of covid-19, state anxiety inventory, and visual analogue pain scale were used. The mean age of the patients was 61.9±14.4 years, 52.0% had undergone total knee arthroplasty, and there was no relationship between Covid-19 fear score and state anxiety score. A positive significant correlation was found between opioid requirement and Covid-19 fear score on the first and second days after surgery. A weak positive correlation was found between non-steroidal anti-inflammatory drug (NSAID) requirement and Covid-19 fear score on the zero, first and second days after surgery. A weak negative correlation was found between paracetamol use and Covid-19 fear score on the first and second days. It was determined that the Covid-19 fear experienced by the patients before surgery was not associated with preoperative anxiety and increased the use of analgesics such as NSAIDs and opioids after surgery.

The Outcomes at 3 Years in 82 Knees with Kellgren and Lawrence 2–3 Osteoarthritis Treated with an Autologous Protein Fluid Concentrate Produced with a Fluid Volume Reducer

Introduction: Knee osteoarthritis (OA) is a highly prevalent and debilitating condition with significant emotional and economic impacts. Current treatment options may only provide temporary pain relief and are not regenerative, thus the progression of knee OA is not deterred and total knee arthroplasty is inevitable. Injection therapies with orthobiologics possess regenerative potential and are an emerging treatment option. We present a prospective study aimed at examining patients with knee OA who had received an autologous platelet concentrate fluid (APCF) injection produced through a fluid volume reducer. Methods: This was an observational review of the results following an APCF injection in a cohort of patients at a single site. Patients were included in the study if they were diagnosed with K/L grade 2–3 knee OA and treated with an APCF knee injection. Patients were excluded if they had obtained an orthobiologic injection in the three months prior to study enrollment or if baseline data were unavailable. Knee score and function score were used to assess patients at the baseline and post-injection follow-ups. Results: Improvements for knee score were statistically significant for the follow-ups at three months, six months, one year, and three years. Function score improved, with statistically significant changes for the three month and three year follow-ups. Conclusions: Our study demonstrates that there is some utility in using APCF injection for knee OA, with improvements that may be sustained up to three years in some patients.

Bizarre Parosteal Osteochondromatous Proliferation With Malignant Transformation and Metastases.

A patient with a benign bizarre parosteal osteochondromatous proliferation (BPOP) located in the anterior knee was treated with resection in preparation for total knee arthroplasty (TKA). The BPOP reoccurred and was treated with re-resection at the time of TKA. The BPOP reoccurred a second time and underwent malignant transformation to a fungating high-grade pleomorphic sarcoma with metastatic lesions. This case highlights the rare potential of a previously benign BPOP to undergo malignant transformation after recurrence. A wide margin resection may be considered primarily when surgery is indicated to prevent recurrence and its potential sequelae. [Orthopedics. 202x;4x(x):xx-xx.].

Comparison of Clinical and Patient Reported Outcomes in One-Sided Cruciate-Retaining Versus Other-Sided Posterior Stabilizing Protheses in Bilateral Simultaneous Total Knee Arthroplasty

Comparison of Clinical and Patient Reported Outcomes in One-Sided Cruciate-Retaining Versus Other-Sided Posterior Stabilizing Protheses in Bilateral Simultaneous Total Knee Arthroplasty

Fixed-bearing medial unicompartmental knee arthroplasty restores pre-arthritic coronal alignment and achieves satisfactory functional outcomes: a retrospective study

PurposeThis study aimed to (1) analyze the Coronal Plane Alignment of the Knee (CPAK) classification in patients undergoing unicompartmental knee arthroplasty (UKA), (2) assess whether UKA can restore pre-arthritic coronal alignment by utilizing the arithmetic hip-knee-ankle angle (aHKA), and (3) evaluate the relationship between patient-reported outcome measures (PROMs) and postoperative alignment following UKA.MethodsWe retrospectively analyzed 152 consecutive patients who underwent fixed-bearing medial UKA. A radiological analysis was conducted using an EOS imaging system. Postoperative alignment was classified as neutral (varus ≤ 3°), mild varus (3° < varus ≤ 7°), or marked varus (varus > 7°) based on the mechanical hip-knee-ankle angle (mHKA). The aHKA was calculated and the CPAK classification was used to categorize knee phenotypes. The PROMs were obtained both before and after the surgery.ResultsA total of 152 knees from 113 patients were included with a mean two-year follow-up. The mean difference between the postoperative mHKA and the estimated aHKA was 0.80° (90% CI 0.35 to 1.24; P = 0.003). Postoperatively, 63 (41.45%) of the 152 knees were in neutral group, 54 (35.53%) mild varus, and 35 (23.03%) marked varus. The neutrally aligned cohort did not exhibit significantly higher scores in range of motion, VAS, HSS, WOMAC, or FJS-12 scores compared to the mild or marked varus cohort (P = 0.205, 0.118, 0.076, 0.140, and 0.788, respectively) during the short-term follow-up.ConclusionNon-robotically assisted, fixed-bearing medial UKA can restore pre-arthritic coronal alignment and achieve satisfactory PROMs. Fixed-bearing medial UKA aims to restore the pre-arthritic alignment rather than achieving neutral mechanical alignment.