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Purpose Kinematic alignment in TKA is supposed to restore function by aligning the components to the premorbid flexion–extension axis instead of altering the joint line and natural kinematic axes of the knee. The purpose of this study was to compare mechanically aligned TKA to kinematic alignment. Methods In this study, 200 patients underwent TKA and were randomly assigned to 2 groups: 100 TKAs were performed using kinematic alignment with custom-made cutting guides in order to complete cruciate-retaining TKA; the other 100 patients underwent TKA that was manually performed using mechanical alignment. The WOMAC and combined Knee Society Score (KSS), as well as radiological alignment, were determined as outcome parameters at the 12-month endpoint. Results WOMAC and KSS significantly improved in both groups. There was a significant difference in both scores between groups in favour of kinematic alignment. Although the kinematic alignment group demonstrated significantly better overall results, more outliers with poor outcomes were also seen in this group. A correlation between post-operative alignment deviation from the initial plan and poor outcomes was also noted. The most important finding of this study is that applying kinematic alignment in TKA achieves comparable results to mechanical alignment in TKA. This study also shows that restoring the premorbid flexion–extension axis of the knee joint leads to better overall functional results. Conclusion Kinematic alignment is a favourable technique for TKA. Clinical relevance The kinematic alignment idea might be a considerable alternative to mechanical alignment in the future. Level of evidence II.

Background Several studies have shown mechanical alignment influences the outcome of TKA. Robotic systems have been developed to improve the precision and accuracy of achieving component position and mechanical alignment. Questions/purposes We determined whether robotic-assisted implantation for TKA (1) improved clinical outcome; (2) improved mechanical axis alignment and implant inclination in the coronal and sagittal planes; (3) improved the balance (flexion and extension gaps); and (4) reduced complications, postoperative drainage, and operative time when compared to conventionally implanted TKA over an intermediate-term (minimum 3-year) followup period. Methods We prospectively randomized 100 patients who underwent unilateral TKA into one of two groups: 50 using a robotic-assisted procedure and 50 using conventional manual techniques. Outcome variables considered were postoperative ROM, WOMAC scores, Hospital for Special Surgery (HSS) knee scores, mechanical axis alignment, flexion/extension gap balance, complications, postoperative drainage, and operative time. Minimum followup was 41 months (mean, 65 months; range, 41–81 months). Results There were no differences in postoperative ROM, WOMAC scores, and HSS knee scores. The robotic-assisted group resulted in no mechanical axis outliers (> ± 3° from neutral) compared to 24% in the conventional group. There were fewer robotic-assisted knees where the flexion gap exceeded the extension gap by 2 mm. The robotic-assisted procedures took an average of 25 minutes longer than the conventional procedures but had less postoperative blood drainage. There were no differences in complications between groups. Conclusions Robotic-assisted TKA appears to reduce the number of mechanical axis alignment outliers and improve the ability to achieve flexion-extension gap balance, without any differences in clinical scores or complications when compared to conventional manual techniques. Level of Evidence Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Purpose Correct positioning and alignment of the prosthesis is a very important factor for durability of prosthesis and implant survival which is improved with the use of technology in total knee arthroplasty. However, the long-term functional outcomes and survivorship are unclear. For this study, it was hypothesized that mechanical axis alignment of lower limb, post-operative joint line restoration, femoral and tibial component alignment is more accurate with the new handheld semi-active robotic-assisted TKA. Method From April-2019 to March-2020, 60 patients with unilateral knee osteoarthritis who underwent total knee arthroplasties were included in this prospective randomised controlled study. Computer generated randomization was used. Study included 48 female patients and 12 male patients. Pre-operative and post-operative radiographic measurements were done and compared between the two groups. Results There was a significant difference between two groups with respect to mechanical axis deviation, joint line deviation and coronal alignment of femoral and tibial prosthesis. Mechanical axis deviation > 3° was seen in eight cases (28.5%) in C-TKA group compared to one case (3.1%) in RA-TKA ( p 0.019). Joint line deviation of 3.5 mm was noted in C-TKA group as compared to 0.9 mm in RA-TKA group ( p < 0.001) which was statistically significant. However, whether this difference of 2.6 mm of joint line elevation between C-TKA and RA-TKA leads to any difference in clinical outcome in terms of knee kinematics and knee flexion needs to be investigated with further studies. Clinically restoring normal joint line is important for improved knee function after primary TKA. No significant difference was noted in femoral component rotation on post-operative computed tomography (CT) scan. Conclusion The novel imageless, handheld semi-autonomous robotic system for TKA is highly accurate with respect to component positioning in coronal plane and mechanical alignment as compared to conventional TKA. Joint line is elevated in conventional TKA but is accurately restored using the robotic-assisted TKA which may lead to better patellofemoral kinematics. Level of evidence I.

Purpose Despite numerous well-conducted studies and meta-analyses, the management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of our study was to compare the clinical and radiological outcomes between patients with and without patellar resurfacing and to determine the influence of resurfacing on patellar tracking with a “patella-friendly” prosthesis. Methods A single-centered prospective randomized controlled study was performed between April 2017 and November 2018. Two hundred and forty-five consecutive patients (250 knees) scheduled for TKA were randomized for patellar resurfacing or patella non-resurfacing. All patients received the same total knee prosthesis and were evaluated clinically and radiologically, including the International Knee Society Score (KSS knee and function), Forgotten Joint Score (FJS), anterior knee pain (AKP), pain when climbing stairs, patellar tilt, and patellar translation. Results Two hundred and twenty-nine knees were available for clinical evaluation and 221 knees for radiographic analysis. The revision rate for patellofemoral cause was 3.1% (7 cases) with no difference between the groups ( p  = 0.217). There was no difference in survival rate between patellar resurfacing (88.3%) and non-resurfacing (85.3%) after 24 months ( p  = 0.599). There were no differences in KSS functional component ( p  = 0.599), KSS knee component ( p  = 0.396), FJS ( p  = 0.798), and AKP ( p  = 0.688) at a mean follow-up of 18 months. There was twice as much stair pain for the non-resurfacing group (17.1% versus 8.5%) ( p  = 0.043). There was patellar tilt in 43% of resurfaced knees ( n  = 50/116) versus 29% in non-resurfaced knees ( n  = 30/105) ( p  = 0.025); however, there was more patellar translation in the non-resurfaced group (21.0% versus 7.8%) ( p  < 0.001). There were no specific complications attributed to the patellar resurfacing procedure. There were four secondary patellar resurfacing procedures (3.6%) in the non-resurfaced group after a mean of 10 ± 7 months (1–17) postoperatively. Conclusion There is no superiority of patellar resurfacing or non-resurfacing in terms of clinical or radiological outcomes at mid-term. Secondary patellar resurfacing is rare. There is not enough evidence to recommend systematic patellar resurfacing with a “patella-friendly” prosthesis. Level of evidence 1.

This trial compared surgery with physical therapy (followed by surgery as needed) in patients with a meniscal tear and mild-to-moderate knee osteoarthritis. Functional outcomes and pain were similar in the two groups at 6 months; 30% of the PT group crossed over to surgery. Symptomatic, radiographically confirmed osteoarthritis of the knee affects more than 9 million people in the United States. 1 Meniscal tears are also highly prevalent, with imaging evidence of a meniscal tear observed in 35% of persons older than 50 years of age; two thirds of these tears are asymptomatic. 2 Meniscal damage is especially prevalent among persons with osteoarthritis 3 , 4 and is frequently treated surgically with arthroscopic partial meniscectomy. This procedure, in which the surgeon trims the torn meniscus back to a stable rim, is performed for a range of indications in more than 465,000 persons annually in the United States. 5 The . . .

Anterior cruciate ligament (ACL) rupture is a common debilitating injury that can cause instability of the knee. We aimed to investigate the best management strategy between reconstructive surgery and non-surgical treatment for patients with a non-acute ACL injury and persistent symptoms of instability. We did a pragmatic, multicentre, superiority, randomised controlled trial in 29 secondary care National Health Service orthopaedic units in the UK. Patients with symptomatic knee problems (instability) consistent with an ACL injury were eligible. We excluded patients with meniscal pathology with characteristics that indicate immediate surgery. Patients were randomly assigned (1:1) by computer to either surgery (reconstruction) or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment), stratified by site and baseline Knee Injury and Osteoarthritis Outcome Score—4 domain version (KOOS4). This management design represented normal practice. The primary outcome was KOOS4 at 18 months after randomisation. The principal analyses were intention-to-treat based, with KOOS4 results analysed using linear regression. This trial is registered with ISRCTN, ISRCTN10110685, and ClinicalTrials.gov, NCT02980367. Between Feb 1, 2017, and April 12, 2020, we recruited 316 patients. 156 (49%) participants were randomly assigned to the surgical reconstruction group and 160 (51%) to the rehabilitation group. Mean KOOS4 at 18 months was 73·0 (SD 18·3) in the surgical group and 64·6 (21·6) in the rehabilitation group. The adjusted mean difference was 7·9 (95% CI 2·5–13·2; p=0·0053) in favour of surgical management. 65 (41%) of 160 patients allocated to rehabilitation underwent subsequent surgery according to protocol within 18 months. 43 (28%) of 156 patients allocated to surgery did not receive their allocated treatment. We found no differences between groups in the proportion of intervention-related complications. Surgical reconstruction as a management strategy for patients with non-acute ACL injury with persistent symptoms of instability was clinically superior and more cost-effective in comparison with rehabilitation management. The UK National Institute for Health Research Health Technology Assessment Programme.

The single-joint hybrid assistive limb (HAL-SJ), an exoskeletal robotic suit, offers functional improvement. In this prospective randomized controlled trial, we investigated the therapeutic effects of knee extension exercises using the HAL-SJ after total knee arthroplasty (TKA). Seventy-six patients with knee osteoarthritis were randomly assigned to HAL-SJ or conventional physical therapy (CPT) groups. The HAL-SJ group underwent exercise using the HAL-SJ for 10 days postoperatively, in addition to CPT; the CPT group underwent only CPT. Pain intensity and active and passive knee extension angles were evaluated preoperatively and on postoperative days 1–10 and weeks 2 and 4. Performance tests and Knee Injury and Osteoarthritis Outcome Scores (KOOS) were evaluated preoperatively and at postoperative weeks 2 and 4. Statistical analysis showed that the HAL-SJ group significantly improved active and passive knee extension angles compared with the CPT group. The HAL-SJ group showed immediate improvement in active knee extension angle through day 5. There were no significant differences in results between the performance tests and KOOS. Knee extension exercises with the HAL-SJ improved knee pain and the angle of extension in the acute phase after TKA.

Objective Computer-assisted surgery (CAS) and patient-specific instrumentation (PSI) are digital techniques to improve the accuracy of implant positioning in total knee arthroplasty (TKA), but their effects on clinical outcomes are still in dispute. The objective of this trial is to evaluate the efficacy and safety of CAS and PSI compared to conventional instrumentation (CI) in TKA. Methods A prospective randomized controlled trial was conducted. A total of 135 patients undergoing TKA were randomized into CAS group, PSI group and CI group with 45 patients in each group. Primary outcome is the coronal mechanical axis of lower extremity. Secondary outcomes include Femoral Rotation Angle (FRA) of the femoral prosthesis, operation time, perioperative blood loss, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS) and complications. Results Outliers of Hip-Knee-Ankle angle (HKA) were 24.4% in CI group, 17.8% in CAS group and 31.1% in PSI group respectively, and there was no significant difference among these 3 groups ( P  > 0.05). Outliers of FRA were 13.3% in CI group, 26.7% in CAS group and 11.1% in PSI group respectively with no significant difference ( P  > 0.05). Operation time was (66.67 ± 12.85)min, (81.67 ± 12.31)min and (52.78 ± 8.62)min in CI, CAS and PSI group. Operation time in CI was longer than PSI and shorter than CAS with significant difference ( P  < 0.01). There was no significant difference in comparison of blood loss, transfusion rate, postoperative WOMAC and FJS ( P  > 0.05). Conclusion CAS and PSI, compared with CI, did not significantly improve clinical outcomes including lower limb alignment, rotation of femoral prosthesis, blood loss, transfusion rate, and function scores. However, CAS was associated with prolonged operation time, whereas PSI resulted in a reduced operation time. Level of evidence Level II. Trial registration ChiCTR-INR-17,012,881 (registration date: 03/10/2017).

Purpose The purpose of this study was to assess the midterm results of total knee arthroplasty (TKA) implanted with a specific computer navigation system in a group of patients (NAV) and to assess the same prosthesis implanted with the conventional technique in another group (CON); we hypothesized that computer navigation surgery would improve implant alignment, functional scores and survival of the implant compared to the conventional technique. Methods From 2008 to 2009, 225 patients were enrolled in the study and randomly assigned in CON and NAV groups; 240 consecutive mobile-bearing ultra-congruent score (Amplitude, Valence, France) TKAs were performed by a single surgeon, 117 using the conventional method and 123 using the computer-navigated approach. Clinical outcome assessment was based on the Knee Society Score (KSS), the Hospital for Special Surgery Knee Score and the Western Ontario Mac Master University Index score. Component survival was calculated by Kaplan–Meier analysis. Results Median follow-up was 6.4 years (range 6–7 years). Two patients were lost to follow-up. No differences were seen between the two groups in age, sex, BMI and side of implantation. Three patients of CON group referred feelings of instability during walking, but clinical tests were all negative. NAV group showed statistical significant better KSS Score and wider ROM and fewer outliers from neutral mechanical axis, lateral distal femoral angle, medial proximal tibial angle and tibial slope in post-operative radiographic assessment. There was one case of early post-operative superficial infection (caused by Staph. Aureus) successfully treated with antibiotics. No mechanical loosening, mobile-bearing dislocation or patellofemoral complication was seen. At 7 years of follow-up, component survival in relation to the risk of aseptic loosening or other complications was 100 %. There were no implant revisions. Conclusion This study demonstrates superior accuracy in implant positioning and statistical significant better functional outcomes of computer-navigated TKA. Computer navigation for TKAs should be used routinely in primary implants. Level of evidence II.

Background Patient-specific instrumentation in TKA has the proposed benefits of improving coronal and sagittal alignment and rotation of the components. In contrast, the literature is inconsistent if the use of patient-specific instrumentation improves alignment in comparison to conventional instrumentation. Depending on the manufacturer, patient-specific instrumentation is based on either MRI or CT scans. However, it is unknown whether one patient-specific instrumentation approach is more accurate than the other and if there is a potential benefit in terms of reduction of duration of surgery. Questions/purposes We compared the accuracy of MRI- and CT-based patient-specific instrumentation with conventional instrumentation and with each other in TKAs. The three approaches also were compared with respect to validated outcomes scores and duration of surgery. Methods A randomized clinical trial was conducted in which 90 patients were enrolled and divided into three groups: CT-based, MRI-based patient-specific instrumentation, and conventional instrumentation. The groups were not different regarding age, male/female sex distribution, and BMI. In all groups, coronal and sagittal alignments were measured on postoperative standing long-leg and lateral radiographs. Component rotation was measured on CT scans. Clinical outcomes (Knee Society and WOMAC scores) were evaluated preoperatively and at a mean of 3 months postoperatively and the duration of surgery was analyzed for each patient. MRI- and CT-based patient-specific instrumentation groups were first compared with conventional instrumentation, the patient-specific instrumentation groups were compared with each other, and all three approaches were compared for clinical outcome measures and duration of surgery. Results Compared with conventional instrumentation MRI- and CT-based patient-specific instrumentation showed higher accuracy regarding the coronal limb axis (MRI versus conventional, 1.0° [range, 0°–4°] versus 4.5° [range, 0°–8°], p < 0.001; CT versus conventional, 3.0° [range, 0°–5°] versus 4.5° [range, 0°–8°], p = 0.02), femoral rotation (MRI versus conventional, 1.0° [range, 0°–2°] versus 4.0° [range, 1°–7°], p < 0.001; CT versus conventional, 1.0° [range, 0°–2°] versus 4.0° [range, 1°–7°], p < 0.001), and tibial slope (MRI versus conventional, 1.0° [range, 0°–2°] versus 3.5° [range, 1°–7°], p < 0.001; CT versus conventional, 1.0° [range, 0°–2°] versus 3.5° [range, 1°–7°], p < 0.001), but the differences were small. Furthermore, MRI-based patient-specific instrumentation showed a smaller deviation in the postoperative coronal mechanical limb axis compared with CT-based patient-specific instrumentation (MRI versus CT, 1.0° [range, 0°–4°] versus 3.0° [range, 0°–5°], p = 0.03), while there was no difference in femoral rotation or tibial slope. Although there was a significant reduction of the duration of surgery in both patient-specific instrumentation groups in comparison to conventional instrumentation (MRI versus conventional, 58 minutes [range, 53–67 minutes] versus 76 minutes [range, 57–83 minutes], p < 0.001; CT versus conventional, 63 minutes [range, 59–69 minutes] versus 76 minutes [range, 57–83 minutes], p < .001), there were no differences in the postoperative Knee Society pain and function and WOMAC scores among the groups. Conclusions Although this study supports that patient-specific instrumentation increased accuracy compared with conventional instrumentation and that MRI-based patient-specific instrumentation is more accurate compared with CT-based patient-specific instrumentation regarding coronal mechanical limb axis, differences are only subtle and of questionable clinical relevance. Because there are no differences in the long-term clinical outcome or survivorship yet available, the widespread use of this technique cannot be recommended. Level of Evidence Level I, therapeutic study. See the Instructions to Authors for a complete description of levels of evidence.