Abstract
Objective
The different cutting mode of robot‐assisted TKAs may influence the accuracy of alignment. The purpose of this study was to compare alignment accuracy and early clinical outcomes between a CT‐based, saw cutting robotic system (MAKO) and a CT‐free, jig‐guided robotic system (ROSA) for total knee arthroplasty (TKA).
Methods
A total of 20 MAKO TKAs and 20 ROSA TKAs from June 2021 to June 2022 were retrospectively analyzed. Differences in the postoperative hip‐knee‐ankle (HKA) angle, lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), posterior tibial slope (PTS) and 3° outlier frequency of the HKA, LDFA, MPTA and PTS were studied at 3 months and 1 year of follow‐up. The operative time and total blood loss (TBL) were compared between these two groups. Clinical outcomes at 1 year after surgery, including range of motion (ROM), Western Ontario McMaster University Osteoarthritis Index (WOMAC) score, and Knee Society Score‐2011 (KSS‐2011), were also compared between these two groups.
Results
The baseline characteristics of the two groups were comparable. There were no significant differences in the mean deviations of postoperative HKA, LDFA, MPTA or PTS between the two groups at 3 months or 1 year (all ps > 0.05). Moreover, there was no significant difference in the percentage of 3° outliers for HKA, LDFA, MPTA, or PTS between the two groups at 3‐month or 1‐year follow‐up (all ps > 0.05). The mean operation time of MAKO was longer than that of ROSA (112.7 ± 12.8 min vs 94.8 ± 23.0 min, p = 0.001), but the mean TBL (1356.7 ± 648.5 mL vs 1384.5 ± 676.3 mL) and transfusion rate (15.0% vs 5.0%) were not significantly different between the two groups (all ps > 0.05). No significant differences were found in postoperative ROM, WOMAC score or KSS score at 1 year (all ps > 0.05).
Conclusion
The MAKO and ROSA had similar accuracy and precision in TKA alignment. The clinical outcomes at 1 year after surgery were also comparable.
Keywords: Alignment, Clinical outcomes, Robotic surgery, Total knee arthroplasty
The MAKO and the ROSA had similar accuracy and precision in coronal alignment in total knee arthroplasty (TKA). The clinical outcomes at 1 year after surgery were also comparable.
Introduction
Total knee arthroplasty (TKA) is the best treatment for late‐stage knee osteoarthritis (KOA).The number of TKAs performed globally is substantial, and the occurrence of TKAs has grown rapidly. 1 The alignment and component position are crucial to successful TKA. 2 Good alignment leads to faster rehabilitation and better function. 3 Component malalignment may cause early failure of a knee prosthesis and is strongly correlated with limited ROM and reduced patient satisfaction. 4 Studies have reported that only 82%–89% of patients are satisfied with the outcomes of their primary TKA. 5
In recent years, robot‐assisted TKA(RATKA) has been developed to improve alignment and prosthesis implantation 6 and may be related to better patient‐reported outcomes. 7 MAKO (Stryker, Kalamazoo, MI, USA) and ROSA (Zimmer Biomet, Omaha, ME, USA) are the two most representative semi active robotic systems. There are two main differences between these two systems. First, the MAKO allows preoperative planning based on CT images of the lower limb. ROSA systems are suitable for either image‐based or imageless procedures. Image‐based procedures require patient‐specific 3D models derived from 2D full‐length plain radiographs using a dedicated algorithm, while imageless procedures are based only on intraoperative landmark acquisition. 8 Second, the MAKO robotic arm, with haptic feedback, holds a saw blade for bone cutting. The system stops sawing when bone resection begins to exceed the predetermined parameters set in the preoperative plan. 9 In contrast, the robotic arm of the ROSA is fitted with a cutting jig. The surgeon makes the incision while the cutting jig is positioned based on the preoperative plan. To date, no study has compared the postoperative radiological and clinical outcomes of TKA with these two robotic systems. 8
The purpose of this study was to compare the outcomes between MAKO‐assisted TKAs and ROSA‐assisted TKAs as follows: (i) postoperative alignment accuracy and implant position; (ii) operative time and blood loss; and (iii) clinical outcomes at the 1‐year follow‐up.
Materials and Methods
Patient Selection
Data were retrospectively collected from 16 patients (20 knees) who underwent TKA with MAKO and 20 patients (20 knees) who underwent TKA with ROSA at Peking University Third Hospital from June 2021 to June 2022. All procedures were performed by a single surgeon who had experience with MAKO or ROSA. The inclusion criteria for patients were as follows: (i) had KOA and underwent primary TKA; (ii) were aged between 55 and 80 years; and (iii) could accept the follow‐up at 3 months and 1 year. The exclusion criteria for patients were as follows: (i) underwent revision knee replacement; (ii) had rheumatoid arthritis or secondary osteoarthritis; and (iii) had severe systemic disease. The baseline data included the following: age, sex, body mass index (BMI), side of intervention, Kellgren–Lawrence grade, hemoglobin concentration, hematocrit, HKA angle, range of motion (ROM), Western Ontario McMaster University Osteoarthritis Index (WOMAC) score and Knee Society Score‐2011 (KSS‐2011). All patients provided written informed consent.
Surgical Procedures
Preoperative planning was performed by surgeons assisted by the MAKO and ROSA based on hip‐knee‐ankle CT and 2D full‐length plain radiographs, respectively. A tourniquet and a medial Para patellar approach were used in every procedure. Following the principle of mechanical alignment, the target HKA angle for all the patients was 180°. A measured resection approach was used for every RATKA.
After the femoral and tibial tracker arrays were secured, bone registration was performed. For the MAKO group, femoral and tibial bone cuts were made using a saw blade attached to the MAKO robotic arm, which is a semiautonomous cutting tool programmed to stop cutting if the blade deviates more than 1 mm from the surgical plan. The amount of bone to be removed is shown in green in the CT‐reconstructed model. In the ROSA group, the robotic arm positioned and held the cutting jig in the desired location according to the surgical plan. Once the cutting jig was set in the correct position, it was pinned to the bone, and the surgeon cut the femur and tibia with a conventional saw blade. After the bone cuts were finished and the trial components were inserted, the appropriate soft tissue was released to balance the flexion and extension gaps in both groups. The goal in the sagittal plane was to achieve full extension under gravity. Triathlon (Stryker, Kalamazoo, MI, USA) was used for the MAKO group, while Persona (Zimmer Biomet, Omaha, ME, USA) was used for the ROSA group; both of these are posterior‐stabilized implants. The operation time ranged from the skin incision to the completion of the wound suture. The total blood loss of the patients was calculated using the Gross equation. 10
All patients received post‐operative patient‐controlled analgesia (PCA) and 50 mg of intravenous Flurbiprofen axetil twice a day. Rivaroxaban 10 mg was taken orally to prevent thrombosis. Patients underwent a standardized post‐operative rehabilitation program with full weight‐bearing and active range of movement exercises commenced from day of surgery. Patients were discharged home at the 4th day postoperatively, knee flexion to a minimum of 90°, independent mobilization with the help of walking aids.
Radiological Outcome Evaluation
Anteroposterior and lateral radiographs of the entire lower extremity were obtained 3 months and 1 year after surgery. The HKA was measured as the lateral angle from the center of the femoral head to the center of the distal femur and the center of the tibia plateau to the center of the ankle joint in the frontal plane. HKA > 180° was defined as varus and HKA > 180° was defined as valgus. The LDFA was measured as the angle between the mechanical axis of the femur and the knee joint line of the femur in the frontal plane. The MPTA was measured as the angle between the tibial knee joint line and the mechanical axis of the tibia in the frontal plane. The PTS was measured as the angle between the anatomical axis of the tibia shaft and the tibial baseplate on the lateral radiograph. Deviations in the HKA, LDFA, and MPTA of more than 3° from 180°, 90°, and 90°, respectively, were defined as outliers. For the PTS, deviations of more than 3° from the robotic plan were defined as outliers. The average deviation was used to compare the accuracy, the standard deviation (SD) was used to compare the precision, and the percentage of outliers relative to the total number of patients was calculated. All the parameters were measured independently and averaged by two professional physicians who were blinded to the groups of patients. The percentage of HKA outliers was defined as the primary outcome.
Clinical Outcome Evaluation
The ROM of the knee joints, WOMAC score, and KSS‐2011 score were collected 1 year after surgery.
Statistical Analysis
The SPSS 26.0 (SPSS, Chicago, IL, USA) was used for statistical analysis. Continuous measurements were expressed as the mean ± standard deviation (SD). According to the normality test, two independent sample t‐tests or Mann–Whitney U‐tests were used for continuous variables. The χ 2‐test was used for categorical variables. A p‐value < 0.05 was considered to indicate statistical significance.
Results
Baseline Characteristics
There were no significant differences in age; sex; BMI; surgical side; Kellgren–Lawrence grade; preoperative HKA angle; HKA angle deviation; Hct; Hb; ROM; WOMAC score; or KSS between the MAKO group and the ROSA group (Table 1).
TABLE 1.
Comparison of baseline patient data.
| Characteristics | MAKO (n = 20) | ROSA (n = 20) | Statistic value | p‐value |
|---|---|---|---|---|
| Age (years) | 66.1 ± 4.9 | 66.1 ± 6.3 | t = −0.056 | 0.956 |
| Sex (male: female) | 11:9 | 7:13 | χ 2 = 1.616 | 0.204 |
| BMI (kg/m2) | 26.6 ± 2.5 | 27.1 ± 3.0 | t = −0.598 | 0.553 |
| Side, (left: right) | 10:10 | 6:14 | χ 2 = 1.667 | 0.197 |
| K/L grade (3:4) | 3:17 | 5:15 | χ 2 = 0.156 | 0.693 |
| Preoperative HKA (°) | 187.7 ± 8.0 | 187.9 ± 7.7 | t = −0.076 | 0.940 |
| Preoperative HKA deviation (°) | 10.3 ± 4.1 | 10.3 ± 3.6 | t = −0.074 | 0.941 |
| Preoperative Hct | 0.40 ± 0.06 | 0.42 ± 0.03 | t = −1.457 | 0.155 |
| Preoperative Hb (g/L) | 130.2 ± 19.5 | 138.3 ± 10.5 | t = −1.644 | 0.111 |
| Preoperative ROM (°) | 102.0 ± 17.8 | 93.5 ± 13.8 | t = 1.643 | 0.109 |
| Preoperative WOMAC | 49.6 ± 13.6 | 43.5 ± 16.0 | t = 1.311 | 0.201 |
| Preoperative KSS | 116.3 ± 15.9 | 118.1 ± 27.7 | t = −0.252 | 0.802 |
| Objective score | 29.7 ± 11.3 | 31.4 ± 16.5 | t = −0.368 | 0.715 |
| Symptom score | 15.0 ± 2.6 | 15.6 ± 3.7 | t = −0.539 | 0.593 |
| Satisfactory value | 17.8 ± 4.3 | 15.5 ± 4.7 | t = 1.620 | 0.114 |
| Surgical expectations | 14.9 ± 0.3 | 14.8 ± 0.5 | t = 0.737 | 0.466 |
| Functional score | 38.9 ± 14.5 | 40.9 ± 18.1 | t = −0.386 | 0.702 |
Abbreviations: BMI, body mass index; Hb, hemoglobin; Hct, hematocrit; HKA, hip–knee–ankle; K/L, Kellgren–Lawrence; KSS, Knee society score; ROM, range of motion; WOMAC, Western Ontario McMaster University Osteoarthritis Index.
Radiological Outcomes
At the 3‐month follow‐up, there was no significant difference in the mean deviation of the postoperative HKA (2.0° ± 1.8° vs 2.9° ± 1.7°), LDFA (2.5° ± 1.3° vs 1.8° ± 1.7°), or MPTA (1.7° ± 1.3° vs 1.3° ± 1.1°) or PTS (1.2° ± 0.7° vs 1.4° ± 0.9°) between the two groups (all ps > 0.05). There was also no significant difference in the percentage of 3° outliers for HKA (15.0% vs 35.0%), LDFA (30.0% vs 25.0%), MPTA (10.0% vs 5.0%) or PTS (5.0% vs 10.0%) between the two groups (all ps > 0.05).
Similar results were found at the 1‐year follow‐up. There was no significant difference in the mean deviation of the postoperative HKA (1.7° ± 1.0° vs 2.1° ± 0.9°), LDFA (2.3° ± 1.1° vs 1.7° ± 1.5°), MPTA (1.6° ± 1.2°vs 1.3° ± 1.0°) or PTS (1.2° ± 0.7° vs 1.3° ± 0.9°) between the two groups (all ps > 0.05). There was also no significant difference in the percentage of 3° outliers for HKA (5.0% vs 15.0%), LDFA (20.0% vs 15.0%), MPTA (10.0% vs 5.0%) or PTS (5.0% vs 10.0%) between the two groups (all ps > 0.05) (Table 2, Figures 1 and 2).
TABLE 2.
Comparison of postoperative alignment and prosthesis position between the MAKO group and the ROSA group.
| Indexes | 3 months after surgery | 1 year after surgery | ||||
|---|---|---|---|---|---|---|
| MAKO (n = 20) | ROSA (n = 20) | p‐value | MAKO (n = 20) | ROSA (n = 20) | p‐value | |
| HKA (°) | 181.0 ± 2.5 | 182.0 ± 2.7 | 0.251 | 180.7 ± 1.9 | 181.3 ± 2.0 | 0.350 |
| HKA deviation (°) | 2.0 ± 1.8 | 2.9 ± 1.7 | 0.134 | 1.7 ± 1.0 | 2.1 ± 0.9 | 0.131 |
| Outliers of HKA (°) | 15.0% (3/20) | 35.0% (7/20) | 0.144 | 10.0% (2/20) | 20.0% (4/20) | 0.661 |
| LDFA (°) | 92.2 ± 1.9 | 91.5 ± 2.0 | 0.273 | 91.9 ± 1.7 | 91.3 ± 1.8 | 0.272 |
| LDFA deviation (°) | 2.5 ± 1.3 | 1.8 ± 1.7 | 0.157 | 2.3 ± 1.1 | 1.7 ± 1.5 | 0.142 |
| Outliers of LDFA (°) | 30.0% (6/20) | 25.0% (5/20) | 0.723 | 20.0% (4/20) | 15.0% (3/20) | 1.000 |
| MPTA (°) | 91.6 ± 1.3 | 89.5 ± 1.7 | <0.001 | 91.2 ± 1.2 | 89.4 ± 1.6 | <0.001 |
| MPTA deviation (°) | 1.7 ± 1.3 | 1.3 ± 1.1 | 0.360 | 1.6 ± 1.2 | 1.3 ± 1.0 | 0.372 |
| Outliers of MPTA (°) | 10.0% (2/20) | 5.0% (1/20) | 1.000 | 10.0% (2/20) | 5.0% (1/20) | 1.000 |
| PTS deviation (°) | 1.2 ± 0.7 | 1.4 ± 0.9 | 0.619 | 1.2 ± 0.7 | 1.3 ± 0.9 | 0.625 |
| Outliers of PTS (°) | 5.0% (1/20) | 10.0% (2/20) | 1.000 | 5.0% (1/20) | 10.0% (2/20) | 1.000 |
Abbreviations: HKA, hip‐knee‐ankle; LDFA, lateral distal femoral angle; MPTA, medial proximal tibial angle; PTS, posterior tibial slope.
FIGURE 1.
Radiological outcomes of saw cutting robotic system (MAKO) and jig‐guided robotic system (ROSA) patients at the 1‐year follow‐up.
FIGURE 2.
(A–C) Pre‐operative and post‐operative (at the follow‐up of 3 months and 1 year) total lower extremity weight‐bearing of patient in saw cutting robotic system (MAKO) group. (D–F) Pre‐operative and post‐operative (at the follow‐up of 3 months and 1 year) total lower extremity weight‐bearing of patient in jig‐guided robotic system (ROSA) group.
Operative Time and Blood Loss
The mean operative time in the MAKO group was longer than that in the ROSA group (112.7 ± 12.8 min vs 94.8 ± 23.0 min, p = 0.004). There was no significant difference in TBL between the MAKO group and the ROSA group (1356.7 ± 648.5 mL vs 1384.5 ± 676.3 mL, p = 0.895). Moreover, there was no significant difference in the transfusion rate between these two groups (15.0% vs 5.0%, p = 0.605) (Table 3).
TABLE 3.
Comparison of operation time, total blood loss and clinical outcomes (1 year after surgery) between the MAKO group and the ROSA group.
| Indexes | MAKO (n = 20) | ROSA (n = 20) | Statistic value | p‐value |
|---|---|---|---|---|
| Operative time (min) | 112.7 ± 12.8 | 94.8 ± 23.0 | t = 3.045 | 0.004 |
| Total blood loss (mL) | 1356.7 ± 648.5 | 1384.5 ± 676.3 | t = −0.133 | 0.895 |
| Transfusion rate (%) | 15.0% (3/20) | 5.0% (1/20) | NA | 0.605 |
| Postoperative ROM(°) | 111.3 ± 9.2 | 110.8 ± 9.6 | t = 0.168 | 0.867 |
| Postoperative WOMAC score | 6.1 ± 8.2 | 4.7 ± 5.1 | t = 0.644 | 0.524 |
| WOMAC score change from baseline | 43.5 ± 16.4 | 38.8 ± 16.1 | t = 0.917 | 0.365 |
| Postoperative KSS | 175.8 ± 21.2 | 168.8 ± 23.0 | t = 1.000 | 0.324 |
| Objective score | 66.7 ± 12.2 | 63.3 ± 15.3 | t = 0.777 | 0.442 |
| Symptom score | 7.2 ± 1.9 | 8.3 ± 2.7 | t = −1.423 | 0.163 |
| Satisfaction score | 28.8 ± 6.0 | 24.0 ± 6.9 | t = 1.972 | 0.056 |
| Surgical expectation score | 10.8 ± 2.3 | 10.9 ± 2.3 | t = −0.136 | 0.892 |
| Functional score | 62.4 ± 11.0 | 61.6 ± 13.8 | t = 0.215 | 0.831 |
| KSS change from baseline | 59.6 ± 23.4 | 50.8 ± 24.5 | t = 1.162 | 0.253 |
| Objective score | 37.0 ± 15.0 | 31.9 ± 18.1 | t = 0.961 | 0.343 |
| Symptom score | 7.8 ± 3.5 | 7.3 ± 3.7 | t = 0.436 | 0.665 |
| Satisfaction score | 11.0 ± 6.2 | 9.4 ± 8.1 | t = 0.699 | 0.489 |
| Surgical expectation score | 4.2 ± 2.3 | 4.0 ± 2.5 | t = 0.261 | 0.796 |
| Functional score | 23.6 ± 16.9 | 20.7 ± 10.7 | t = 0.637 | 0.528 |
Abbreviations: KSS, Knee Society Score; ROM, range of motion; WOMAC, Western Ontario McMaster University Osteoarthritis Index.
Clinical Outcomes
There was no significant difference in ROM between the MAKO group and the ROSA group (111.3 ± 9.2 vs 110.8 ± 9.6, p = 0.867) at 1 year after the operation. Moreover, there was no significant difference in the WOMAC score between the two groups at 1 year after the operation (6.1 ± 8.2 vs 4.7 ± 5.1, p = 0.524).Compared with the baseline data, the postoperative WOMAC score was significantly lower (43.5 ± 16.4 for the MAKO group and 38.8 ± 16.1 for the ROSA group). The improvement in the WOMAC score was not significantly different (p = 0.365). There was no significant difference in the objective score (66.7 ± 12.2 vs 63.3 ± 15.3, p = 0.442), symptom score (7.2 ± 1.9 vs 8.3 ± 2.7, p = 0.163), satisfaction score (28.8 ± 6.0 vs 24.0 ± 6.9, p = 0.056), surgical expectation score (10.8 ± 2.3 vs 10.9 ± 2.3, p = 0.892), functional score (62.4 ± 11.0 vs 61.6 ± 13.8, p = 0.831) or total KSS (175.8 ± 21.2 vs 168.8 ± 23.0, p = 0.324) at 1 year after the operation. There were no significant differences in objective score improvement (37.0 ± 15.0 vs 31.9 ± 18.1, p = 0.343), symptom score improvement (7.8 ± 3.5 vs 7.3 ± 3.7, p = 0.665), satisfaction score improvement (11.0 ± 6.2 vs 9.4 ± 8.1, p = 0.489), surgical expectation score improvement (4.2 ± 2.3 vs 4.0 ± 2.5, p = 0.796), functional score improvement (23.6 ± 16.9 vs 20.7 ± 10.7, p = 0.528) or total KSS improvement (59.6 ± 23.4 vs 50.8 ± 24.5, p = 0.253) compared with the baseline data. (Table 3).
Discussion
Lower limb alignment and component position are key factors for favorable outcomes in TKA. Controlling the HKA angle deviation after TKA within ±3° is generally considered the relative “safe area.” 11 In recent years, different robotic systems have been developed to ameliorate accuracy in bone resection and component positioning, as well as to improve postoperative functional outcomes. This is the first study to compare the radiological outcomes and clinical outcomes between a CT‐based, saw cutting robotic system and a CT‐free, jig‐guided robotic system. No significant differences were found in postoperative alignment, component position, total blood loss or clinical outcomes at 1 year after the operation between the two systems. The average operative time of MAKO‐assisted TKAs was longer than that of ROSA‐assisted TKAs.
Accuracy and Alignment in the Coronal Plane
The MAKO system for TKA has been available for more than a decade. Based on the patient's CT scan, the MAKO can be used for 3D preoperative planning, including component size and bone resection. The robotic arm alerts surgeons when they deviate from the surgical plan through tactile feedback or movement restrictions. Several studies 12 , 13 , 14 have demonstrated the high accuracy and precision of MAKO‐assisted TKA. The newly developed ROSA system is regarded as a collaborative robotic system: the robotic arm places and holds the guide in the right place, while the surgeon handles the saw and performs the cuts, which is more in line with the doctor's operating habits. This system does not require preoperative CT imaging, thus reducing patients' radiation exposure. Two cadaveric studies 15 , 16 reported a high accuracy of the ROSA system. An in vivo study 17 demonstrated that using the ROSA system in TKA is reliable for performing accurate bone cuts and achieving planned angles and resections.
It has been reported that 93% of postoperative CT measurements are ≤ 3 degrees of the intraoperative measurements in CT‐based robotic‐assisted TKA. 18 Compared with the results of previous studies, the percentages of HKA outliers in the MAKO and ROSA groups at the 3‐month follow‐up were relatively greater (15% and 35%, respectively). However, this percentage decreased to 10% and 20% at the 1‐year follow‐up. One possible explanation is that patients' lower limbs cannot be fully straightened during the early follow‐up period, resulting in nonstandard anteroposterior radiographs of the entire lower extremity.
Accuracy and Alignment in the Sagittal Plane
Radiological evaluation in the sagittal plane is also highly important. The posterior tibial slope in TKA impacts knee flexion, balance, and ligament strain. A study indicated unsatisfactory accuracy of the ROSA in sagittal plane osteotomy, with 26% outliers of 3° for PTS. 19 Our results showed that the proportion of outliers for PTS in the ROSA group was only 10%, which was not significantly different from that in the MAKO group and did not show any lower accuracy than coronal alignment.
Clinical Outcomes
Regarding clinical outcomes, a systematic review 20 showed that, compared with conventional TKA, MAKO‐assisted TKA improved alignment and implant positioning, but the early functional outcomes were comparable or slightly superior. A retrospective matched‐pair comparative study 21 reported that the complications and functional outcomes were comparable between ROSA‐assisted TKA and conventional TKA. A prospective matched cohort study 22 demonstrated that patients in the ROSA group had better satisfaction and patient‐reported outcome measures (PROMs) at 6 months after the operation than patients in the conventional group did. In this study, there were no significant differences in clinical outcomes at the follow‐up of 1 year between the MAKO group and the ROSA group.
Operation Time and Blood Loss
In our study, the average operation time of MAKO was longer than that of ROSA, which may be partly attributed to the differences in the methods used for bone cutting. A learning curve for the operation time was reported for seven patients in MAKO‐assisted TKA, but there was no learning curve for the accuracy of implant positioning. 23 The learning curve for the ROSA system was approximately 6–11 cases, as previously reported. 24 Despite the differences in operation time, the total blood loss and blood transfusion rate were similar between the two groups.
Limitations and Strengths
This study has limitations. It was a retrospective study, and the sample size was relatively small, which may affect the results. More cases are needed to compare these two robotic‐assisted TKA systems. Also, postoperative imaging evaluation was based on X‐rays rather than three‐dimensional CT measurements. Although our technicians were skillfully trained, the X‐ray technician taking each radiograph was not controlled, leaving room for variability in the results.
The study also has strengths. This is the first study to compare the outcomes between saw cutting robots and jig‐guided robots. We comprehensively compared the postoperative alignments both in the coronal and sagittal planes. Preoperative differences in age, gender, BMI, surgical side, preoperative HKA, HKA deviation and KSS score between the two groups were not statistically significant, suggesting that the two groups had strong comparability. In addition, the group of patients was kept confidential from the measuring physician, which also reduced research bias.
Conclusions
This is the first study to compare a CT‐based, saw cutting robotic system (MAKO) and a CT‐free, jig‐guided robotic system (ROSA). Based on differences in preoperative images and bone cutting procedures, no differences were found in alignment accuracy or early clinical outcomes.
Conflict of Interest Statement
All authors declared that there are no competing interests.
Ethics Statement
This study was approved by the Ethics Committee of Peking University Third Hospital, Beijing, China (Approval No. D2021079).
Author Contributions
GZ and XW are joint first authors. HT obtained funding and designed the study. GZ, XW, and XG were involved in the data collection and analysis. GZ drafted the manuscript. ZL and HT contributed to critical revision of the manuscript for important intellectual content and approved the final version of the manuscript. HT is the study guarantor. All the authors read and approved the final manuscript.
Funding Information
This work was supported by Natural Science Foundation of Beijing Municipality (No. 23G12187) and the Clinical Cohort Construction Program of Peking University Third Hospital, (No. BYSYDL2023007).
Acknowledgments
Not applicable.
Ge Zhou and Xinguang Wang are co‐first authors.
All authors listed meet the authorship criteria according to the latest guidelines of the International Committee of Medical Journal Editors, and all authors are in agreement with the manuscript.
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