Man Soo Kim

Accurate measurement of tibial rotation in anterior cruciate ligament (ACL) injury remains challenging because most devices rely on skin-referenced measure

Background and Objectives: Effective early postoperative pain control is essential for optimal recovery following total knee arthroplasty (TKA). In addition to pharmacological pain management, the choice of anesthetic agents and surgical technique can significantly impact postoperative outcomes. Remimazolam and robotic-assisted TKA (RA-TKA) have recently gained attention due to their potential advantages. This study aims to evaluate the effects of remimazolam and RA-TKA on acute postoperative pain compared with conventional TKA (C-TKA) and standard anesthetic protocols. Materials and Methods: In this retrospective observational study, 460 patients undergoing elective unilateral TKA were divided in to four groups based on surgical technique and anesthetic agents; RA-TKA with remimazolam (Group RR, n = 115), C-TKA with remimazolam (Group CR, n = 134), RA-TKA with conventional anesthesia (Group RC, n = 79), and C-TKA with conventional anesthesia (Group CC, n = 152). Remimazolam was administered at 6 mg/kg/h for induction and 1 mg/kg/h for maintenance, whereas conventional anesthesia was induced with propofol (1.5 mg/kg) and maintained with sevoflurane (1.5~2.0 vol%). The primary endpoint was acute postoperative pain, assessed via patient-controlled analgesia (PCA) consumption and supplemental analgesic use on the day of surgery. Secondary endpoints included total PCA consumption and additional analgesic use during the first 72 h, recovery room stay, discharge scores, and the incidence of postoperative nausea and vomiting (PONV). Results: Group RR required significantly fewer additional analgesics on the day of surgery than the other groups. Although group RR and group CR exhibited prolonged recovery room stay and lower discharge scores, these outcomes were not correlated with PCA consumption or supplementary analgesic use. RA-TKA was associated with approximately a 31% reduction in additional analgesic use compared with C-TKA, indicating a major contribution of the surgical technique to early postoperative pain control. Remimazolam alone did not demonstrate an independent effect on acute pain management. Conclusions: RA-TKA combined with remimazolam significantly reduced the need for additional analgesics on the day of surgery, highlighting a synergistic effect of the anesthetic and surgical approach. These findings support RA-TKA with remimazolam as an effective strategy for managing early postoperative pain following TKA.

Background and Objectives: Performance of robot-assisted total knee arthroplasty (TKA) procedures has continued to increase in popularity. However, tourniquet use is necessary for longer periods of time in robot-assisted TKA than conventional manual TKA because the robot-assisted procedure requires an additional registration process. The use of tourniquets for long periods increases the risk of hidden blood loss and ischemic soft tissue injury in the lower extremity. The purpose of this study was to compare the value of performing robot-assisted TKA without the use of a tourniquet to that of performing this surgery with the use of a tourniquet. Parameters we assessed were blood loss, degree of postoperative thigh and knee pain, and occurrence of early post-operative complications. Materials and Methods: Data from 100 consecutive patients who underwent primary unilateral robot-assisted TKA between July 2024 and July 2025 were included in this study’s analyses. Patients were divided into three groups chronologically. The first 29 patients comprised group 1, the early tourniquet group; the next 30 patients were assigned to group 2, the no tourniquet group; and group 3 was the late tourniquet group and comprised the remaining 41 subjects. However, because allocation was chronological rather than randomized, the outcomes of later groups may partly reflect the surgeon’s accumulated experience (learning curve), which should be considered when interpreting the results. The primary outcome measure was estimated blood loss (EBL). The secondary outcome measures included transfusion rate, visual analog scale (VAS) pain scores for the knee and thigh on the third postoperative day, readmission rate due to surgical complications, superficial and deep infection rate, length of operation, and length of tourniquet use. Results: Group 2 participants, the no tourniquet participants, experienced significantly greater EBL on postoperative days (PODs) 1, 2, and 3 compared to the subjects assigned to groups 1 and 3 (p = 0.003, p < 0.001, and p = 0.005, respectively). However, there were no significant differences in transfusion rates (p = 0.290) among the 3 groups. VAS scores for knee and thigh pain were also not significantly different among the three groups (all p-values > 0.05). Three patients in group 1 (10.3%), one patient in group 2 (3.3%), and one patient in group 3 (2.4%) were readmitted for complications related to wound healing (p = 0.289). Additionally, two patients in group 1 developed superficial wound infections from which the causative bacteria were cultured. No infections were observed in the other groups (p = 0.082), however. Two patients in group 1 and two patients in group 2 experienced symptomatic deep vein thrombosis (DVT) (p = 0.235). No group 3 patients experienced DVT, and only one patient in group 2 was confirmed with DVT using an enhanced CT scan (p = 0.308). Group 3 patients had shorter lengths of surgery (p < 0.001) than group 1 and 2 patients and had shorter periods of tourniquet use (p = 0.034) than group 1 patients. Conclusions: Tourniquet non-use in robot-assisted TKA surgeries was associated with greater EBL in acute postoperative periods, but this finding was not accompanied by any change in transfusion rate. Tourniquet non-use was not clinically beneficial for reducing immediate postoperative thigh and knee pain or reducing the prevalence of early post-operative complications. Tourniquet use in robot-assisted TKA may be beneficial because of the advantages its use provides in maintaining a clear surgical field and in facilitating the cementing process.

Background Performance of robot-assisted total knee arthroplasty (TKA) procedures has continued to increase in popularity. However, tourniquet use is necessary for longer periods of time in robot-assisted TKA than conventional manual TKA because the robot-assisted procedure requires an additional registration process. The use of tourniquets for long periods increases the risk of hidden blood loss and ischemic soft tissue injury in the lower extremity. The purpose of this study was to compare the value of performing robot-assisted TKA without the use of a tourniquet to that of performing this surgery with the use of a tourniquet. Parameters we assessed were blood loss, degree of postoperative thigh and knee pain, and occurrence of early post-operative complications. Methods Data from 100 consecutive patients who underwent primary unilateral robot-assisted TKA between July 2024 and July 2025 were included in this study’s analyses. Patients were divided into three groups chronologically. The first 29 patients comprised group 1, the early tourniquet group; the next 30 patients were assigned to group 2, the no tourniquet group; and group 3 was the late tourniquet group and was comprised of the remaining 41 subjects. The primary outcome measure was estimated blood loss (EBL). The secondary outcome measures included transfusion rate, visual analog scale (VAS) pain scores for the knee and thigh on the third postoperative day, readmission rate due to surgical complications, superficial and deep infection rate, length of operation, and length of tourniquet use. Results Group 2 participants, the no tourniquet participants, experienced significantly greater EBL on postoperative days (PODs) 1, 2, and 3 compared to the subjects assigned to groups 1 and 3 (p = 0.003, p < 0.001, and p = 0.005, respectively). However, there were no significant differences in transfusion rates (p = 0.290) among the 3 groups. VAS scores for knee and thigh pain were also not significantly different among the three groups (all p-values > 0.05). Three patients in group 1 (10.3%), one patient in group 2 (3.3%), and one patient in group 3 (2.4%) were readmitted for complications related to wound healing (p = 0.289). Additionally, two patients in group 1 developed superficial wound infections from which the causative bacteria were cultured. No infections were observed in the other groups (p = 0.082), however. Two patients in group 1 and two patients in group 2 experienced symptomatic deep vein thrombosis (DVT) (p = 0.235). No group 3 patients experienced DVT, and only one patient in group 2 was confirmed with DVT using an enhanced CT scan (p = 0.308). Group 3 patients had shorter lengths of surgery (p < 0.001) than group 1 and 2 patients and had shorter periods of tourniquet use (p = 0.034) than group 1 patients. Conclusion Tourniquet non-use in robot-assisted TKA surgeries was associated with greater EBL in acute postoperative periods, but this finding was not accompanied by any change in transfusion rate. Tourniquet non-use was not clinically beneficial for reducing immediate postoperative thigh and knee pain or reducing the prevalence of early post-operative complications. Tourniquet use in robot-assisted TKA is warranted because of the advantages this use provides in maintaining a clear surgical field and in facilitating of the cementing process.

(1) Background: Knee osteoarthritis (KOA) induces pain, stiffness, and impaired mobility, particularly in aging populations. Despite providing symptom relief, the long-term efficacy of intra-articular hyaluronic acid (HA) injections remains unclear. With its longer intra-articular residence time and potential chondroprotective effects, porcine-derived atelocollagen is an alternative to HA. We aimed to compare the safety and efficacy of collagen versus HA injections in symptomatic KOA. (2) Methods: This retrospective observational study included 40 patients with KOA who received either two cycles of collagen or HA injections at 6-month intervals. Clinical outcomes were assessed using the visual analog scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and 6 months after the first and second injections (Cycle 1 and Cycle 2, respectively). Patient satisfaction and adverse events were recorded. Non-inferiority analysis was conducted for VAS and WOMAC score changes. (3) Results: Significant intragroup improvements in VAS and WOMAC scores were noted after each injection cycle (p < 0.05), albeit without significant between-group differences, non-inferiority of collagen to HA based on predefined margins, and comparable patient-reported satisfaction (>85% reported improvement after each cycle), with similar incidence of mild adverse events (collagen: 20%, HA: 25%, p = 0.705). (4) Conclusions: Intra-articular collagen injections were clinically non-inferior to HA in reducing pain and improving function in patients with KOA across two treatment cycles. Given its favorable safety profile and potential structural benefits, collagen may serve as a viable alternative injectable therapy for the non-surgical management of KOA.

This narrative review aims to provide an in-depth understanding of the biomechanical consequences of medial meniscus posterior root tears (MMPRTs), with a particular focus on the role of hoop tension in meniscal function. By revisiting fundamental principles such as load transmission, contact mechanics, and structural stabilization, this review elucidates how MMPRTs compromise both the integrity and function of the knee joint. The disruption of hoop tension is analyzed across various tear patterns, and through a synthesis of biomechanical experiments, the superiority and necessity of anatomical structural restoration over conservative management or meniscectomy are emphasized. A comprehensive grasp of these biomechanical foundations offers a critical perspective on the pathomechanics of MMPRTs and serves as a basis for more rational, evidence-based surgical decision-making in clinical practice.

(1) Background: Knee osteoarthritis (KOA) induces pain, stiffness, and impaired mobility, particularly in aging populations. Despite providing symptom relief, the long-term efficacy of intra-articular hyaluronic acid (HA) injections remains unclear. With its longer intra-articular residence time and potential chondroprotective effects, porcine-derived atelocollagen is an alternative to HA. We aimed to compare the safety and efficacy of collagen versus HA injections in symptomatic KOA. (2) Methods: This retrospective observational study included 40 patients with KOA who received either two cycles of collagen or HA injections at 6-month intervals. Clinical outcomes were assessed, using the Visual Analog Scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), at baseline and at 6 months after the first and second injections (Cycle 1 and Cycle 2, respectively). Patient satisfaction and adverse events were recorded. Non-inferiority analysis was conducted for VAS and WOMAC score changes. (3) Results: Significant intragroup improvements in VAS and WOMAC scores were noted after each injection cycle (p85% reported improvement after each cycle), with similar incidence of mild adverse events (collagen: 20%, HA: 25%, p=0.705). (4) Conclusion: Intra-articular collagen injections were clinically non-inferior to HA in reducing pain and improving function in patients with KOA across two treatment cycles. Given its favorable safety profile and potential structural benefits, collagen may serve as a viable alternative injectable therapy for the non-surgical management of KOA.

Background and Objectives: Central sensitization (CS) has been identified as a significant factor influencing persistent pain and dissatisfaction following total knee arthroplasty (TKA). However, its effect on unicompartmental knee arthroplasty (UKA) remains largely unexplored. Unlike TKA, UKA preserves most native knee structures, with less bone cut, leading to different postoperative pain mechanisms. Nevertheless, the revision rate for unexplained pain following UKA is higher than after TKA. This study investigates the influence of preoperative CS on pain and dissatisfaction after UKA. Materials and Methods: This retrospective cohort study included 121 patients who underwent primary UKA for medial compartment osteoarthritis of the knee. Patients were screened for CS preoperatively using the Central Sensitization Inventory (CSI) and categorized into a CS group (CSI ≥ 40; n = 26) and a non-CS group (CSI < 40; n = 95). Clinical outcomes, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS), and patient satisfaction, were assessed at the 2-year postoperative follow-up visit. A multivariate regression analysis was used to determine the risk factors for postoperative dissatisfaction. Results: The CS group reported significantly worse postoperative WOMAC pain, function, and total scores than the non-CS group (all p < 0.05). FJS was also significantly worse in the CS group than in the non-CS group (64.4 vs. 72.7, respectively, p = 0.005). Patient satisfaction was significantly lower in the CS group than in the non-CS group (65.4% vs. 95.8%, respectively, p < 0.001). The multivariate logistic regression analysis demonstrated that patients with a CSI score ≥ 40 had an 11.349-fold increased likelihood of dissatisfaction after UKA (95% CI: 2.315–55.626, p = 0.003). Conclusions: This study underscores the importance of recognizing CS as a critical determinant of postoperative pain and functional recovery following UKA. Patients with high CSI scores experience greater pain, increased joint awareness, and overall poorer satisfaction despite technically successful surgeries.