Clinical Benefit of Robotic-Assisted Total Knee Arthroplasty over Conventional Total Knee Arthroplasty When Using Mobile-Bearing Implants.

Background and Objectives: As a treatment modality for advanced knee osteoarthritis, total knee arthroplasty is well established and has been performed on many patients over time. To improve surgical outcomes, fixed-bearing implant insertion with robotic-assisted TKA has been introduced; however, the insertion of mobile-bearing (MB) implants with the same method is challenging. The aim of this study was to compare the short-term postoperative follow-up outcomes of MB implant insertion using a robotic-assisted TKA system and conventional TKA. Materials and Methods: We investigated functional improvement in the knees of 60 patients who underwent the insertion of MB implants using either robotic-assisted TKA or conventional TKA. Isokinetic muscular function, range of motion, the Western Ontario and McMaster Universities Osteoarthritis Index score, visual analog scale (VAS) score, and Knee Society Score (KSS) were measured 6 months after surgery. The statistical analysis of outcome measurements was performed using the Mann-Whitney U test and the Wilcoxon signed-rank test. Results: Some isokinetic muscular functions, as well as Knee Society Scores (pain and function) and VAS scores, were significantly higher in patients who underwent MB insertion with robotic-assisted TKA than in those who underwent conventional TKA. Conclusions: When an MB implant is inserted using a robotic-assisted TKA system, a better surgical outcome can be expected.

Assessment of preoperative planning and intraoperative accuracy of the AIKNEE system for total knee arthroplasty.

BACKGROUND: The aim of this retrospective study was to evaluate the effectiveness and accuracy of the AIKNEE system in preoperative planning and intraoperative alignment for total knee arthroplasty (TKA). METHODS: A total of 64 patients were planned preoperatively by the AIKNEE system, including the measurement of mechanical femorotibial angle (mFTA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) using three-dimensional reconstructed images. Intraoperatively, the actual prosthesis size and alignment were compared to the planned parameters. Postoperative outcomes, including pain levels, range of motion (ROM), and Knee Scoring System (KSS) scores, were assessed after surgery. Statistical analyses were performed to evaluate the correlation between alignment deviations and postoperative function. RESULTS: The AIKNEE system accurately predicted the prosthesis size in thirty-one of femoral cases (48%) and forty-seven of tibial cases (73%). Deviations of mFTA, LDFA, and MPTA from the target value were within 3° in 88%, 92%, and 95% of cases, respectively. A significant improvement was observed in postoperative pain, ROM, and KSS scores (p < 0.001). Correlation analysis revealed that greater deviations in mFTA and LDFA were associated with increased pain (p = 0.004, 0.047) and lower KSS scores (p = 0.027). CONCLUSION: The AIKNEE system demonstrated promising results in predicting prosthesis size and achieved alignment within the desired range in a majority of cases. Postoperative outcomes, including pain levels and functional improvement, were favorable.

Cementless Total Knee Arthroplasty: A State-of-the-Art Review.

¼ The demographic profile of candidates for total knee arthroplasty (TKA) is shifting toward younger and more active individuals.¼ While cemented fixation remains the gold standard in TKA, the interest is growing in exploring cementless fixation as a potentially more durable alternative.¼ Advances in manufacturing technologies are enhancing the prospects for superior long-term biological fixation.¼ Current research indicates that intermediate to long-term outcomes of modern cementless TKA designs are comparable with traditional cemented designs.¼ The selection of appropriate patients is critical to the success of cementless fixation techniques in TKA.¼ There is a need for high-quality research to better understand the potential differences and relative benefits of cemented vs. cementless TKA systems.

Effect of body mass index on 30-day complication rate and implant survival rate after simultaneous bilateral unicompartmental knee arthroplasty: a multicentre retrospective study.

OBJECTIVE: The practice of simultaneous bilateral unicompartmental knee arthroplasty (SBUKA) remains a topic of debate, particularly in patients with obesity. Thus, the purpose of this study was to assess the impact of body mass index (BMI) on the 30-day complication rate and the survival rate of the implant following SBUKA. METHODS: We retrospectively examined the clinical records of 245 patients (490 knees) who underwent SBUKA at the Affiliated Hospital of Qingdao University and the Third Hospital of Hebei Medical University between January 2010 and December 2020. Patients were categorised based on their BMI at the time of surgery into four groups: normal weight (BMI 18.5 to 22.9 kg/m2), overweight (BMI 23.0 to 24.9 kg/m2), obese (BMI 25.0 to 29.9 kg/m2), and severely obese (BMI ≥30 kg/m2). Variables such as length of hospital stay, duration of surgery, and costs of hospitalisation were compared across all groups. Additionally, we recorded the 30-day postoperative complication rate and the time from surgery to any required revision. The Kaplan-Meier survival analysis was employed to evaluate and compare the implant survival rates. RESULTS: The follow-up period for the 245 patients ranged from 39 to 114 months, with an average of 77.05±18.71 months. The incidence of complications within 30 days post-surgery did not significantly differ across the groups (χ2 = 1.102, p = 0.777). The implant survival rates from the lowest to the highest BMI groups were 97.14%, 93.9%, 94.44%, and 96.43%, respectively. Both the rate of implant revision (χ2 =1.612, p = 0.657) and the survival curves of the implants (p = 0.639) showed no statistically significant differences among the groups. CONCLUSIONS: BMI did not influence the 30-day complication rate nor the survival rate of implants following SBUKA, suggesting that SBUKA should not be contraindicated based on BMI alone.

Commercially available activity monitors such as the fitbit charge and apple watch show poor validity in patients with gait aids after total knee arthroplasty.

PURPOSE: The aim of this study is to determine the validity of consumer grade step counter devices during the early recovery period after knee replacement surgery. METHODS: Twenty-three participants wore a Fitbit Charge or Apple Watch Series 4 smart watch and performed a walking test along a 50-metre hallway. There were 9 males and 14 females included in the study with an average age of 68.5 years and BMI of 32. Each patient wore both the Fitbit Charge and Apple Watch while completing the walking test and an observer counted the ground truth value using a thumb-push tally counter. This test was repeated pre-operatively with no gait aid, immediately post operatively with a walker, at 6 weeks follow up with a cane and at 6 months with no gait aid. Bland-Altman plots were performed for all walking tests to compare the agreement between measurement techniques. RESULTS: Mean overall agreement of step count for pre-operative and at 6 months for subjects walking without gait aids was excellent for both the Apple Watch vs. actual and Fitbit vs. actual with bias values ranging from - 0.87 to 1.36 with limits of agreement (LOA) ranging between - 10.82 and 15.91. While using a walker both devices showed extremely little agreement with the actual step count with bias values between 22.5 and 24.37 with LOA between 11.7 and 33.3. At 6 weeks post-op while using a cane, both the Apple Watch and Fitbit devices had a range of bias values between - 2.8 and 5.73 with LOA between - 13.51 and 24.97. CONCLUSIONS: These devices show poor validity in the early post operative setting, especially with the use of gait aids, and therefore results should be interpreted with caution.

Limited Revision with a Newly Designed Hinge Device for the Treatment of Mega-Prosthesis Hinge Failure: Two Case Reports.

BACKGROUND: Surgical treatment for hinge failure in mega-prosthesis continues to be a challenge. This study introduces a new method for treating hinge failure by using a unilateral prosthesis and hinge revision. CASE PRESENTATION: We here present two patients who underwent mega-prosthesis reconstruction after resection of osteosarcoma in the distal femur. To address the issue of knee hyperextension after mega-prosthesis reconstruction, one patient underwent three revision surgeries, two surgeries were performed using the original hinge, and one surgery involved a newly designed hinge. To resolve the problem of dislocation, one patient underwent three revisions, with the first two revisions not involving hinge replacement and the third revision involving a newly designed hinge. Two replacements of unilateral prosthesis and hinge renovations were successful. CONCLUSIONS: Unilateral prosthesis and newly designed hinge device revision are effective in treating the failure of old-fashioned mega-prosthesis hinges.

Evaluating the accuracy of a new robotically assisted system in cadaveric total knee arthroplasty procedures.

BACKGROUND: Robot-assisted total knee arthroplasty (TKA) has been shown to facilitate high-precision bone resection, which is an important goal in TKA. The aim of this cadaveric study was to analyze the accuracy of the target angle and bone resection thickness of a recently introduced robotic TKA system. METHODS: This study used 4 frozen cadaveric specimens (8 knees), 2 different implant designs, navigation, and a robotic system. The 4 surgeons who participated in this study were trained and familiar with the basic principles and operating procedures of this system. The angle of the bone cuts performed using the robotic system was compared with the target angles from the intraoperative plan. For each bone cut, the resection thickness was recorded and compared with the planned resection thickness. RESULTS: The mean angular difference for all specimens was less than 1°, and the standard deviation was less than 2°. The mean difference between the planned and measured angles was close to 0 and not significantly different from 0 except for the difference in the frontal tibial component angle, which was 0.88°. The mean difference in the hip-knee-ankle axis angle was - 0.21°± 1.06°. The mean bone resection difference for all specimens was less than 1 mm, and the standard deviation was less than 0.5 mm. CONCLUSIONS: The results of the cadaveric experimental study showed that the new TKA system can realize highly accurate bone cuts and achieve planned angles and resection thicknesses. Despite the limitations of small sample sizes and large differences between cadaveric and clinical patients, the accuracy of cadaveric experiments provides strong support for subsequent clinical trials.

Failure of the Yoke With a Rotating-Hinge Total Knee Arthroplasty: A Case Report.

CASE: A patient underwent revision of a total knee replacement to a cementless rotating-hinge prosthesis. The femoral component became loose, but due to the patient's frailty and cognitive decline, revision was not performed. Subsequently, the yoke failed, dissociating the femoral and tibial components, necessitating a single-stage revision. CONCLUSION: This case underlines the need for robust fixation of components of rotating-hinge knee replacements to avoid mechanical failures. It contributes valuable insights to the limited literature on yoke failure in total knee arthroplasty, emphasizing the importance of implant design, patient selection, and surgical technique to prevent such complications.

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.

The peak force to push a trial tibial insert into position cannot be used to select the correct thickness in total knee arthroplasty.

An objective of a total knee arthroplasty (TKA) is to restore native (i.e. healthy) function, and a crucial step is determining the correct insert thickness for each patient. If the insert is too thick, then stiffness results, and if too thin, then instability results. Two methods to determine the insert thickness are by manually assessing the joint laxity and by using a trial insert with goniometric markings that measures the internal-external rotation of the trial with respect to a mark on the femoral component. The former is qualitative and depends on the surgeon's experience and 'feel' and while the latter is quantitative, it can be used only with an insert with medial ball-in-socket conformity. An unexplored method is to measure the force required to push a trial insert into position. To determine whether this method has merit, the push force was measured in 30 patients undergoing unrestricted kinematically aligned TKA using an insert with ball-in-socket medial conformity, a flat lateral surface, and retention of the posterior cruciate ligament. During surgery, the surgeon determined three appropriate thicknesses to test from a selection ranging from 10 mm to 14 mm in 1 mm increments. The peak push forces going from an insert 1 mm thinner than the correct thickness as determined by an insert goniometer and from the correct thickness to 1 mm thicker were measured. Mean peak forces for the different insert thicknesses were 127 ± 104 N, 127 ± 95 N, and 144 ± 96 N for 1 mm thinner, correct, and 1 mm thicker, respectively, and did not differ (p = 0.3210). As a result, measurement of peak force during trial positioning of a tibial insert cannot be used to identify the correct thickness for all insert designs.

Long-term functional success and robust implant survival in lateral unicompartmental knee arthroplasty: A case series with a mean follow-up of twenty two and a half years.

PURPOSE: Lateral unicompartmental knee arthroplasty (UKA) is an accepted treatment option in cases of end-stage lateral osteoarthritis. While lateral UKA has many proposed advantages compared to total knee arthroplasty, its technical challenges and relatively small number of cases make this an uncommon procedure. The aim of this study was to report the survivorship and functional outcomes beyond 20 years of follow-up of isolated UKA. METHODS: Between January 1988 and October 2003, 54 lateral UKAs were performed in a single center. The fitted prosthesis was a fixed plate and cemented polyethylene (PE). All patients had isolated lateral tibiofemoral osteoarthritis, including five open meniscectomies, three arthroscopies, and three open reductions of lateral tibial plateau fractures. Patients with a minimum of 20 years of follow-up were included in the final analysis. RESULTS: Of the 54 UKA, 22 died before reaching the minimum follow-up period and four were lost to follow-up. Twenty-eight were included in the final analysis. Among them, 21 patients remained alive and an additional seven were deceased after 20 years. The mean age at the last follow-up was 84.8 ± 11.9 years with a mean follow-up duration of 22.5 ± 2.1 years. Of the 28 knees, eight underwent revision surgery (5 for the progression of osteoarthritis; 2 for aseptic loosening; 1 for PE wear). Kaplan-Meier survival analysis revealed a survival rate at 20 and 25 years of 72.3% (CI 59.1; 88.6). The average time to revision was 14.9 ± 4.9 years. At the last follow-up, the mean function Knee Society Score (KSS) was 41.5 ± 32.9 and the mean objective KSS score was 79.4 ± 9.7. In the unrevised population, 94.7% of patients (n = 18) reported being satisfied or very satisfied with the surgery. CONCLUSION: Lateral UKA remains a viable treatment option for patients with isolated lateral tibiofemoral osteoarthritis, providing satisfactory 20-year implant survivorship and high patient satisfaction.

Enhancing robotic precision in medial UKA: Image-based robot-assisted system had higher accuracy in implant positioning than imageless robot-assisted system across 292 knees.

PURPOSE: The objective of this study was to compare the degree of accuracy in implant positioning and limb alignment offered by two robot-assisted (RA) systems: an image-based robot-assisted (IBRA) versus an imageless robot-assisted (ILRA) system for the treatment of medial knee osteoarthritis with unicompartmental knee arthroplasty (UKA). METHODS: This retrospective radiographic study included medial UKAs performed between 2011 and 2023. Radiographic measurements taken preoperatively and at 1-year postoperative control visit focusing on hip-knee-ankle angle (HKA), posterior tibial slope (PTS), tibial component coronal alignment relative to Cartier's angle and restoration of proper joint line (JL) height were analyzed. Outliers for postoperative measurements were defined as follows: HKA <175° or >180°, PTS <2° or >8°, >3° or <-3° alterations in Cartier's angle and ±2 mm changes in the height of the joint line. RESULTS: The final sample consisted of 292 medial UKAs: 95 (32.5%) with an IBRA system and 197 (67.5%) with an ILRA system. Implant positioning and limb alignment were more accurate in the group of patients treated with IBRA, HKA (77.9% vs. 67.5%, p = 0.07), PTS (93.7% vs. 82.7%, p = 0.01), restoration of tibial varus relative to Cartier's angle (87.4% vs. 65%, p < 0.001) and restoration of JL height (81.1% vs. 69.5%, p = 0.04). CONCLUSION: Medial UKA surgery using an IBRA system was associated with a higher degree of accuracy in implant positioning and postoperative limb alignment as compared to an ILRA system. This is a valuable contribution to help communicate the advantages of using this surgical technique and improve its reproducibility. LEVEL OF EVIDENCE: Level III, Retrospective cohort study.

Robotic-assisted patellofemoral arthroplasty provides excellent implant survivorship and high patient satisfaction at mid-term follow-up.

PURPOSE: Robotic adoption in knee surgery has yielded several benefits, but its application in patellofemoral arthroplasty (PFA) remains barely reported. The purpose of this study was to determine implant survival, patient satisfaction, and functional outcomes after robotic-assisted PFA at an intermediate follow-up. METHODS: This prospective analysis targeted 18 knees of 16 consecutive patients who underwent robot-aided PFA with three-year minimum follow-up (range, 3 to 6 years). Each patient was evaluated collecting pre-operative and post-operative medical record data, including range of motion, radiographic images, and multiple scores, such as VAS, APKS, and OKS. RESULTS: At surgery, the mean age was 55.4 years ± 14.4 (range, 32 to 78 years), and the mean BMI was 26.8 kg/m² ±5.2 (range, 20 to 36). Etiologies of patellofemoral osteoarthritis included idiopathic degeneration (28%), post-traumatic (33%), and dysplasia (39%). Pre-implantation scores were VAS 7.9 ± 1.4, AKPS 34.6 ± 23.3, and OKS 17.3 ± 10.3. One implant was revised with primary total knee arthroplasty for osteoarthritis progression. Clinical and radiographic follow-up showed no signs of loosening or infection. The maximum flexion reached an average of 131.1°±10.5° (range, 110° to 145°), accompanied by significantly improved score results (P-value < 0.01): VAS 1.1 ± 1.4, AKPS 90.2 ± 8.6, and OKS 46.3 ± 1.8. CONCLUSIONS: At 3 years after robotic assisted patellofemoral arthroplasty, excellent implant survival and patient satisfaction rates can be expected along with significantly improved functional and pain control outcomes. Although the limitations imposed by the restricted cohort, these findings indicate that robotic assistance in PFA is both safe and effective at intermediate follow-up.

Mid-term survivorship and clinical outcomes of revision knee arthroplasty using a mobile bearing tibial tray: A single-center registry review.

BACKGROUND: Revision total knee arthroplasty can successfully restore function and relieve pain for patients with failed knee replacements. Mobile-bearing implants were designed to provide greater congruency between the implant and the polyethylene insert. The goal of this study was to review the clinical outcomes and survivorship for a revision mobile-bearing tibial design. METHODS: A retrospective outcomes review was conducted to assess survivorship and clinical outcomes for a mobile bearing tibial tray, used with metaphyseal sleeves, in revision total knee arthroplasty. RESULTS: At time of furthest follow-up, KM estimates (95% CI; n with further follow-up) for all-cause revision were 82.5% (75.8%; 87.5%; 42) at 7 years for the clinical assumption (CA), and 88.5% (84.4%,91.6%; 53) at 13 years for the registry assumption (RA). For revision of the tray as the endpoint, survivorship estimates were 93.4% (87.0%,96.7%; 42) at 7 years for CA, and 96.2% (93.2%,97.9%; 53) at 13 years for RA. CONCLUSION: In this single-center registry evaluation, we found excellent mid-term survivorship and clinical outcomes for a mobile-bearing tibial tray used with metaphyseal sleeves in revision total knee arthroplasty.

Aseptic midterm survival rates between different cemented tibial stem designs in hinged total knee arthroplasty: a 6-year evaluation from the German Arthroplasty Registry.

INTRODUCTION: The rate of revision TKA and thus the use of hinged implants (HI) steadily rises. Aseptic loosening lies on the top of the failure patterns. However, no evidence exists until now based on national scale high-caseloads that analyzes the impact of cemented HI stem-design on aseptic survival rates. METHODS: Data on aseptic HI-revisions with full-cemented tibia-stems were conducted from the German Arthroplasty Registry. Cases were divided in primary HI (PHI) and HI used in revision operations (RHI). Endpoint was a new revision following either a PHI or an RHI. The impact of stem conicity (conical vs. cylindrical), diameter (≤ 13 mm vs. > 13 mm), length (≤ 90 mm vs. > 90 mm) and offset on the 6-Year-Cumulative-Aseptic-Revision-Rate (6Y-CARR) was estimated via Kaplan-Meier curve and compared between groups via Log-Rank-Tests. RESULTS: 3953 PHI and 2032 RHI fulfilled inclusion-criteria. Stem conicity had no impact on 6Y-CARR (p = 0.08 and p = 0.8). Diameter > 13 mm hat an impact on PHI (p = 0.05) with lower 6Y-CARR but not on RHI (p = 0.2). Length > 90 mm showed significantly worst 6Y-CARR in PHI (p = 0.0001) but not in RHI (p = 0.3). Offset-stems showed significantly better 6Y-CARR in PHI (p = 0.04), but not in RHI (p = 0.7). CONCLUSION: There was no significant impact of the cemented tibia-stem conicity on 6Y-CARR, neither in PHI nor in RHI. The effect of length, diameter and offset on the 6Y-CARR observed in the PHI, was not detectable in the more complex RHI-cases reflecting its limited clinical relevance by itself in more multifactorial backgrounds. Therefore, results must be interpreted with caution due to considerable system-effects and different utilization-scenarios.

Small deviations between planned and performed bone cuts using a CT-based robotic-arm-assisted total knee arthroplasty system.

PURPOSE: Computed tomography (CT)-based robotic system for total knee arthroplasty (TKA) has shown improved accuracy compared to conventional. This study was designed to (1) confirm the accuracy of the robotic system in achieving the plan and (2) establish the alignment and positioning deviation between final components and planning, by measuring the discrepancy between final implant alignment and the corresponding planned cut. METHODS: Ninety-six cementless robotic-arm assisted (RA) TKAs were assessed. Bone resections were performed using the haptically controlled robotic arm. Alignment in the coronal and sagittal plane and resection depth of the distal femoral and proximal tibial cuts were recorded with a navigation planar probe. After final components were impacted, the probe was positioned on each implant surface to determine its alignment and positioning. RESULTS: The mean tibial resections and implanted tibial component's positioning were 0.4 mm (standard deviation, SD: 0.6) and 0.9 mm (SD: 0.8), respectively, higher than planned (p < 0.01). The tibial sagittal cut had 19/96 cases (19.8%) of ±1° outliers from plan. In 40/96 cases (41.7%), the tibial component was more prominent than planned of more than 1 mm. The mean femoral resections and impacted femoral component's positioning was 0.1 mm (SD: 0.8) and 0.2 mm (SD: 0.7), respectively, higher than planned. In 23/96 cases (24.0%), the femoral sagittal cut and femoral component coronal alignment deviated more than ±1° from plan. CONCLUSIONS: The computed tomography-based robotic-assisted TKA system showed good accuracy regarding bone preparation and component's positioning relative to the planning. Cementless tibial component impaction resulted in the most deviation from plan, with a large proportion of cases resulting in being more prominent than planned. LEVEL OF EVIDENCE: Level III.

Outcomes of rotating versus pure hinge knee arthroplasty in the setting of one-stage exchange for periprosthetic joint infection.

PURPOSE: Rotating or pure hinge knee prostheses are often used in case of periprosthetic joint infection (PJI). Five-year survival data of rotating hinge implants ranging from 52 to 90%, whereas pure hinge data are sparse. This study describes the results of both hinge knee prostheses after one-stage septic exchange. METHODS: One hundred sixty-seven one-stage septic exchanges of a primary unconstrained total knee arthroplasty (TKA) to a cemented hinge prosthesis (117 rotating and 50 pure hinge TKAs) performed between 2008 and 2017 were retrospectively reviewed. Exclusion criteria were stem extensions or augments used in primary TKA, history of extensor mechanism reconstruction, and a follow-up less than two years after surgery. Rates of reinfection, mechanical failures, and all-cause revision-free survival data were documented. RESULTS: At five years, the all-cause revision-free survival was 77% (95% CI 69 to 82). Thirty-one patients (19%) had further revision for aseptic reasons. In the rotating hinge group, the mechanical failure rate was more than twice as high as in the pure hinge group (13% vs 6%), significantly influenced by higher body weight. At a mean follow-up of 6.7 years, 21 (13%) patients had a reinfection and underwent a further surgery. Reinfection rates did not differ between the two groups. CONCLUSION: The use of hinge TKA in the revision of PJI shows favourable five year infection-free and all-cause revision-free survival rates of 91% and 77%, respectively. Our study showed poorer results of the rotating hinge design. These results may help surgeons to choose proper implants in case of septic knee revision.

Stepping Up Recovery: Integrating Patient-reported Outcome Measures and Wearable Technology for Rehabilitation Following Knee Arthroplasty.

Improvement after knee arthroplasty (KA) is often measured using patient-reported outcome measures (PROMs). However, PROMs are limited due to their subjectivity. Therefore, wearable technology is becoming commonly utilized to objectively assess physical activity and function. We assessed the correlation between PROMs and step/stair flight counts in total (TKA) and partial knee arthroplasty (PKA) patients.Analysis of a multicenter, prospective, longitudinal cohort study investigating the collection of average daily step and stair flight counts, was performed. Subjects (N = 1,844 TKA patients and N = 489 PKA patients) completed the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) and provided numerical rating scale pain scores pre- and postoperatively. Only patients who reported living in a multilevel home environment (N = 896 TKA patients and N = 258 PKA patients) were included in analysis of stair flight counts. Pearson correlation coefficients were calculated to determine correlations between variables.Among TKA patients, pain scores demonstrated a negative correlation to mean step counts at preoperative (r = -0.14, p < 0.0001) and 1-month follow-up (r = -0.14, p < 0.0001). Similar negative correlations were true for pain and stair flight counts at preoperative (r = -0.16, p < 0.0001) and 1-month follow-up (r = -0.11, p = 0.006). KOOS JR scores demonstrated weak positive correlations with mean step counts at preoperative (r = 0.19, p < 0.0001) and 1-month postoperative (r = 0.17, p < 0.0001). Similar positive correlations were true for KOOS JR scores and stair flight counts preoperatively (r = 0.13, p = 0.0002) and at 1-month postoperatively (r = 0.10, p = 0.0048). For PKA patients, correlations between pain and KOOS JR with step/stair counts demonstrated similar directionality.Given the correlation between wearable-generated data and PROMs, wearable technology may be beneficial in evaluating patient outcomes following KA. By combining subjective feedback with the objective data, health care providers can gain a holistic view of patients' progress and tailor treatment plans accordingly.

Performance of medial pivot, posterior stabilized and rotating platform total knee arthroplasty based on anteroposterior stability and patient-reported outcome measures; a multicentre double-blinded randomized controlled trial of 210 knees.

BACKGROUND: Despite advancements in total knee arthroplasty (TKA), 10-20% of patients remain dissatisfied after surgery. Improved anteroposterior (AP) stability provided by medial pivot (MP) implants may theoretically lead to higher patient satisfaction. METHODS: AP stability and patient-reported outcome measures (PROMs) at one-year postsurgery were compared between patients who underwent TKA with MP- (n = 121), posterior stabilized (PS; n = 53) and rotating platform (RP; n = 57) implants in a double-blind multicentre randomized controlled trial (Dutch Trial Register: NL6856, 21-02-2018). AP stability was assessed at 30°, 60° and 90° of knee flexion using a KT-2000 arthrometer. PROMs were measured preoperative and one-year postsurgery. RESULTS: MP-TKA provided significant better AP stability at early flexion (30°) compared to PS- and RP-TKA (median [IQR]; 1.79 [1.14-2.77] mm vs. 3.31 [2.51-4.08] mm vs. 2.82 [1.80-4.03] mm, p < 0.001). Additionally, MP-TKA provided significant better AP stability at mid-flexion (60°) compared to PS-TKA (1.75 [1.23-2.36] mm vs. 2.14 [1.49-2.83] mm, p = 0.014). PROM improvements were comparable between implant designs. AP laxity of ≥ 4 mm at early flexion was independently of implant design associated with significantly worse Kujala scores. The incidence of ≥ 4 mm AP laxity at any knee angle was however not significantly different between implant designs. CONCLUSION: MP-, PS- and RP-TKA all provide excellent and comparable results. Although MP-TKA provided better AP stability at early flexion compared to PS- and RP-TKA, this was found to be unrelated to improved PROMs in favour of MP-TKA. More studies focusing on early and mid-flexion performance based differences between MP and other TKA designs are required to confirm our findings. Other non-implant related factors may play a more important role in the performance of TKA and are potentially worthwhile examining.

Characterization of the Relative Change in Objective and Subjective Metrics by Baselining Patients Who Have Wearable Technology Before Total Knee Arthroplasty.

BACKGROUND: Wearable sensors and associated supporting technologies (ie, patient applications) can provide both objective (joint position, step counts, etc.) and subjective data (ie, pain scores and patient-reported outcome measures) to track a patient's episode of care. Establishing a subjective and objective baseline of a patient's experience may arguably be beneficial for multiple reasons, including setting recovery expectations for the patient and demonstrating the effectiveness or success of the intervention. METHODS: In this pilot study, we characterized a subset of patients (n = 82 from 7 surgeons) using a wearable sensor system at least 6 days before total knee arthroplasty and provided postsurgical data up to 50 days postintervention. The 5-day average before surgery for total step counts (activity), achieved flexion and extension on a progress test (functional limit) and visual analog scale daily pain score were calculated. The difference from baseline was then calculated for each patient for each day postsurgery and reported as averages. RESULTS: On average, a patient will experience a relative deficit of 4,000 steps immediately following surgery that will return to near-baseline levels 50 days postintervention. A 30° deficit in flexion and a 10° deficit in extension will return at a similar rate as steps. Relative pain scores will worsen with an increase of approximately 3 points immediately following surgery. However, pain will decrease by 2 points relative to baseline between 40 and 50 days. CONCLUSIONS: The results of this pilot study demonstrate a method to baseline a patient's presurgical subjective and objective data and to provide a reference for postsurgical recovery expectations. Applications for these data include benchmarking for evaluating intervention success as well as setting patient expectations.