The Knee-Fix study: study protocol for a randomised controlled trial evaluating cemented and cementless components in total knee arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is an effective procedure for patients with a variety of knee conditions. The main cause of aseptic TKA failure is implant loosening, which has been linked to poor cement mantle quality. Cementless components were introduced to offer better longer-term biological fixation through osseointegration; however, early designs led to increased rate of revision due to a lack of initial press-fit and bony ingrowth. Newer highly porous metal designs may alleviate this issue but randomised data of fully uncemented TKA (tibial, femoral, patella) is lacking. The aim of the Knee-Fix study is to investigate the long-term implant survival and patient outcomes of fully uncemented compared with cemented fixation in TKA. Our study hypothesis was that uncemented TKA would be as clinically reliable and durable as the gold-standard cemented TKA. METHODS: The Knee-Fix study is a two-arm, single-blinded, non-inferiority randomised controlled trial with 160 patients in each arm and follow-up at 6 weeks, 6 months, 12 months, 24 months, 5 years and 10 years. The primary outcome of interest is implant fixation, which will be measured by assessment of postoperative progressive radiolucencies with the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Secondary outcome measures are patient-reported outcomes, measured using Oxford Knee Score (OKS), International Knee Society System (IKSS), Forgotten Joint Score-12 (FJS-12), EuroQol (EQ-5D-5L), VAS Pain, Patient Satisfaction Score and Net Promoter Score. DISCUSSION: While cemented fixation remains the gold standard, a growing proportion of TKA are now implanted cementless. Highly porous metal cementless components for TKA can offer several benefits including potentially improved biological fixation; however, long-term outcomes need further investigation. This prospective study will help discern long-term differences between the two techniques. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12616001624471 . Registered trial name: Knee-Fix study (Cemented vs Uncemented Total Knee Replacement). Registered on 24 November 2016.

A prospective randomised controlled trial of mechanical axis with soft tissue release balancing vs functional alignment with bony resection balancing in total knee replacement-a study using Stryker Mako robotic arm-assisted technology.

BACKGROUND: Improving the functional outcome following total knee arthroplasty (TKA) by using different alignment techniques remains controversial. The surgical techniques and technologies used so far to obtain these alignments have all suffered from inaccuracies. The use of robotic technology to plan and execute the bony resection provides increased accuracy for these various alignment techniques and may determine which will deliver superior function. Functional alignment (FA) is a newer surgical technique that aims to position the prosthesis with respect to each patients' specific bony anatomy whilst minimising disruption to the soft tissue envelope. This trial aims to compare the patient and surgical outcomes of FA to the current gold standard surgical technique, mechanical alignment (MA), under randomised and blinded conditions. METHODS: Patients with symptomatic knee osteoarthritis will be prospectively recruited. Following informed consent, 240 patients will be randomised to either a MA surgical technique (the control group) or a FA surgical technique (the intervention group) at a ratio of 4:1 using a random number generator. All patients will undergo computer tomography (CT) based robotic arm-assisted surgery to execute planned implant positioning and alignment with high levels of accuracy. The primary outcome is the forgotten joint score (FJS) at 2 years post-operation. Secondary outcome measures include patient reported outcome measures of post-operative rehabilitation, pain, function and satisfaction, as well as limb alignment, implant revisions and adverse events. Intention-to-treat and per-protocol population analysis will also be conducted. Standardisation of the surgical system and care pathways will minimise variation and assist in both patient and physiotherapist blinding. Ethical approval was obtained from the Northern B Health and Disability Ethics Committee (20/NTB/10). DISCUSSION: Currently, MA remains the gold standard in knee replacement due to proven outcomes and excellent long-term survivorship. There are many alternative alignment techniques in the literature, all with the goal of improving patient outcomes. This study is unique in that it leverages an advanced analytics tool to assist the surgeon in achieving balance. Both alignment techniques will be executed with high precision using the CT-based robotic arm-assisted surgery system which will minimise surgical variation. This trial design will help determine if FA delivers superior outcomes for patients. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Registry (ANZCTR), ACTRN12620000009910 . Registered on 9 January 2020. CLINICALTRIALS: gov, NCT04600583 . Registered on 29 September 2020.

Comparable outcomes of in-cement revision and uncemented modular stem revision for Vancouver B2 periprosthetic femoral fracture at 5 years.

INTRODUCTION: Periprosthetic femoral fractures (PFF) are detrimental for patients. Vancouver B2 fractures about a cemented stem can be revised to a longer uncemented stem or using an in-cement revision, if the cement mantle is adequate. There are reports documenting the success of both techniques. The aim of this single centre study was to perform a direct comparison of these two procedures. MATERIALS AND METHODS: A retrospective study of consecutive Vancouver B2 PFFs around a cemented stem during 16 years was performed. All study cases were treated either using an in-cement revision or with an uncemented stem revision. Preoperatively, the groups were compared based upon age, gender, ASA, BMI, and Charlson comorbidity score. The outcome measures were surgical time, complications, in-hospital stay, revisions, 1-year readmission rate, and survivorship. RESULTS: After a median of 3.5 years, there were 70 patients in the uncemented and 31 in the in-cement group. There was no difference in any of the preoperative variables. Surgical time was shorter for in-cement revisions by a mean of 45 min (p < 0.001). There was no difference in in-hospital stay, surgical complications or readmissions. Implant survival at 5 years was 93.5% for the in-cement and 94.4% for the uncemented revision (p = 0.946). Patient survivorship at 5 years was 62.5% for the in-cement and 69.8% for the uncemented group (p = 0.094). CONCLUSIONS: This study demonstrates that in-cement revision is a valid treatment option for Vancouver B2 fractures, comparable to uncemented stem revision, if certain criteria are met. There was no difference in revision rate, patient survivorship, complications, readmissions or in-hospital stay.

Incidence of venous thromboembolism after total hip, total knee and hip fracture surgery at Waitemata District Health Board following a peer-reviewed audit.

AIM: The incidence of venous thromboembolism (VTE) following arthroplasty and hip fracture surgery remains an important metric for quality and financial reasons. An audit at our institution between 2006-2010 showed a higher VTE rate than international data did at the time. This study aims to determine rates of DVT and PE in patients undergoing hip and knee arthroplasty and hip fracture surgery at Waitemata District Health Board (Waitemata DHB) between 1 January 2013 and 31 December 2016. METHODS: This study is a retrospective review of all VTE within three months of elective hip or knee replacement or hip fracture surgery. Data were identified for the period between 2013 and 2016 from Waitemata DHB patient databases, including a dedicated VTE database. RESULTS: The current rates of deep vein thrombosis (DVT) and pulmonary embolism (PE) at our institution following hip or knee arthroplasty or hip fracture surgery are 1.5% and 0.6% respectively, a lower rate than 2.3% and 0.9% respectively in 2006-2010. DVTs were significantly more prevalent after hip fracture surgery than after elective hip or knee arthroplasty, and 71% of DVTs were confined to the distal veins. Of the patients undergoing surgery, 93% received post-operative chemoprophylaxis, mainly aspirin or low molecular-weight heparin (LMWH). CONCLUSION: There has been a significant reduction in VTE rates following elective hip and knee joint replacement and hip fracture surgery between the time periods. This occurred over a period when Waitemata DHB introduced a multi-modal, interdisciplinary team approach to VTE prophylaxis utilising enhanced recovery after surgery (ERAS) pathways. These measures may therefore have contributed to the reduction in VTEs.

No Difference in 5-year Clinical or Radiographic Outcomes Between Kinematic and Mechanical Alignment in TKA: A Randomized Controlled Trial.

BACKGROUND: In kinematic alignment in TKA, the aim is to match the implant's position to the pre-arthritic anatomy of an individual patient, in contrast to the traditional goal of neutral mechanical alignment. However, there are limited mid-term, comparative data for survivorship and functional outcomes for these two techniques. QUESTIONS/PURPOSES: In the setting of a randomized, controlled trial at 5 years, is there a difference between kinematic alignment and mechanical alignment in TKA in terms of (1) patient-reported outcome measures, (2) survivorship free from revision or reoperation, and (3) the incidence of radiographic aseptic loosening? METHODS: In the initial study, 99 primary TKAs for osteoarthritis were randomized to either the mechanical alignment (n = 50) or kinematic alignment (n = 49) group. Computer navigation was used in the mechanical alignment group, and patient-specific cutting blocks were used in the kinematic alignment group. At 5 years, 95% (48 of 50) of mechanical alignment and 96% (47 of 49) of kinematic alignment TKAs were available for follow-up. Knee function was assessed using the Knee Society Score (KSS), VAS, Oxford Knee Score (OKS), WOMAC, Forgotten Joint Score (FJS) and EuroQol 5D. Survivorship free from reoperation (any reason) and revision (change or addition of any component) was determined via Kaplan-Meier analysis. Radiographs were assessed for signs of aseptic loosening (as defined by the presence of progressive radiolucent lines in two or more zones) by a single blinded observer. RESULTS: At 5 years, there were no differences in any patient-reported outcome measure between the two groups. For example, the mean OKS did not differ between the two groups (kinematic alignment: 41.4 ± 7.2 versus mechanical alignment: 41.7 ± 6.3; difference -0.3 [95% confidence interval - 3.2 to 2.5]; p = 0.99). At 5 years, survivorship free from reoperation was 92.2 (95% CI 80.4 to 97.0) for mechanical alignment and 89.7 (95% CI 77.0 to 95.6) for kinematic alignment (log rank test; p = 0.674), survivorship free from revision was 94.1 (95% CI 82.9 to 98.1) for mechanical alignment and 95.9 (95% CI 84.5 to 99.0) for kinematic alignment (log rank test; p = 0.681). At 5 years, one patient demonstrated radiographic aseptic loosening for the mechanical alignment group; no cases were identified for the kinematic alignment group. CONCLUSIONS: We found no mid-term functional or radiographic differences between TKAs with mechanical alignment or kinematic alignment. The anticipated improvements in patient-reported outcomes with kinematic alignment were not realized. Because kinematic alignment results in a high proportion of patients whose tibial components are inserted in varus, loosening remains a potential long-term concern. Given the unknown impact on long-term survivorship of the substantial alignment alterations with kinematic alignment, our findings do not support the routine use of kinematic alignment outside of a research setting. LEVEL OF EVIDENCE: Level I, therapeutic study.

A Comparison of Walking Gait Following Mechanical and Kinematic Alignment in Total Knee Joint Replacement.

BACKGROUND: Although previous studies have compared radiological, pain, and function scores in kinematically aligned (KA) and mechanically aligned (MA) total knee arthroplasty (TKA), no previous studies have undertaken a three-dimensional (3D) gait analysis in these groups. This study compared kinematic and kinetic variables recorded during level walking in patients at least 2 years post-surgery who underwent an MA or KA procedure. METHODS: Utilizing a 9-camera motion analysis system, gait analysis was undertaken on 29 patients (MA = 15, KA = 14). A 9-camera motion analysis system was used to collect 3D kinematic data of the involved and uninvolved limbs during walking at a self-selected speed. Additionally, 3D ground reaction forces and moments during the stance phase were recorded, and an inverse dynamics approach was utilized to analyze these data. RESULTS: There were no significant differences in spatial-temporal variables between MA and KA groups (P > .05). Local minima and maxima for knee joint angles were not significantly different (P > .05) across involved and uninvolved legs and MA/KA groups in any of the 3 planes of motion. Principal component analysis revealed a significant difference (P < .05) in the transverse plane moment in late stance. No other significant differences were observed for knee, hip, or ankle joint moments. CONCLUSION: Differences in gait parameters across the KA and MA groups at 2 years post-surgery were insufficient to support either one of the operative procedures over the other.

The Chitranjan S. Ranawat Award : No Difference in 2-year Functional Outcomes Using Kinematic versus Mechanical Alignment in TKA: A Randomized Controlled Clinical Trial.

BACKGROUND: Neutral mechanical alignment (MA) in total knee arthroplasty (TKA) aims to position femoral and tibial components perpendicular to the mechanical axis of the limb. In contrast, kinematic alignment (KA) attempts to match implant position to the prearthritic anatomy of the individual patient with the aim of improving functional outcome. However, comparative data between the two techniques are lacking. QUESTIONS/PURPOSES: In this randomized trial, we asked: (1) Are 2-year patient-reported outcome scores enhanced in patients with KA compared with an MA technique? (2) How does postoperative component alignment differ between the techniques? (3) Is the proportion of patients undergoing reoperation at 2 years different between the techniques? METHODS: Ninety-nine primary TKAs in 95 patients were randomized to either MA (n = 50) or KA (n = 49) groups. A pilot study of 20 TKAs was performed before this trial using the same patient-specific guides positioning in kinematic alignment. In the KA group, patient-specific cutting blocks were manufactured using individual preoperative MRI data. In the MA group, computer navigation was used to ensure neutral mechanical alignment accuracy. Postoperative alignment was assessed with CT scan, and functional scores (including the Oxford Knee Score, WOMAC, and the Forgotten Joint Score) were assessed preoperatively and at 6 weeks, 6 months, and 1 and 2 years postoperatively. No patients were lost to followup. We set sample size at a minimum of 45 patients per treatment arm based on a 5-point improvement in the mean Oxford Knee Score (OKS; the previously reported minimum clinically significant difference for the OKS in TKA), a pooled SD of 8.3, 80% power, and a two-sided significance level of 5%. RESULTS: We observed no difference in 2-year change scores (postoperative minus preoperative score) in KA versus MA patients for the OKS (mean 21, SD 8 versus 20, SD 8, least square means 1.0, 95% confidence interval [CI], -1.4 to 3.4, p = 0.4), WOMAC score (mean 38, SD 18 versus 35, SD 8, least square means 3, 95% CI, -3.2 to 8.9, p = 0.3), or Forgotten Joint score (28 SD 37 versus 28, SD 28, least square means 0.8, 95% CI, -9.1-10.7, p = 0.8). Postoperative hip-knee-ankle axis was not different between groups (mean KA 0.4° varus SD 3.5 versus MA 0.7° varus SD 2.0), but in the KA group, the tibial component was a mean 1.9° more varus than the MA group (95% CI, 0.8°-3.0°, p = 0.003) and the femoral component in 1.6° more valgus (95% CI, -2.5° to -0.7°, p = 0.003). Complication rates were not different between groups. CONCLUSIONS: We found no difference in 2-year patient-reported outcome scores in TKAs implanted using the KA versus an MA technique. The theoretical advantages of improved pain and function that form the basis of the design rationale of KA were not observed in this study. Currently, it is unknown whether the alterations in component alignment seen with KA will compromise long-term survivorship of TKA. In this study, we were unable to demonstrate an advantage to KA in terms of pain or function that would justify this risk. LEVEL OF EVIDENCE: Level I, therapeutic study.