One in five patients remain unsatisfied due to ongoing pain and impaired mobility following total knee arthroplasty (TKA). It is important if surgeons can pre-operatively identify which patients may be at risk for poor outcomes after TKA. The purpose of this study was to determine if there is an association between pre-operative measures and post-operative outcomes in patients who underwent TKA.

This study included 28 patients (female = 12 / male = 16, age = 63.6 ± 6.9, BMI = 29.9 ± 7.4 kg/m2) with knee osteoarthritis who were scheduled to undergo TKA. All surgeries were performed by the same surgeon (GD), and a subvastus approach was performed for all patients. Patients visited the gait lab within one-month of surgery and 12 months following surgery. At the gait lab, patients completed the knee injury and osteoarthritis outcome score (KOOS), a timed up and go (TUG), and walking task. Variables of interest included the five KOOS sub-scores (symptoms, pain, activities of daily living, sport & recreation, and quality of life), completion time for the TUG, walking speed, and peak knee biomechanics variables (flexion angle, abduction moment, power absorption). A Pearson's product-moment correlation was run to assess the relationship between pre-operative measures and post-operative outcomes in the TKA patients.

Preliminary analyses showed the relationship to be linear with all variables normally distributed, as assessed by Shapiro-Wilk's test (p > .05), and there were no outliers. There were no statistically significant correlations between any of the pre-operative KOOS sub-scores and any of the post-operative biomechanical outcomes. Pre-operative TUG time had a statistically significant, moderate positive correlation with post-operative peak knee abduction moments [r(14) = .597, p < .001] and peak knee power absorption [r(14) = .498, p = .007], with pre-operative TUG time explaining 36% of the variability in peak knee abduction moment and 25% of the variability in peak knee power absorption. Pre-operative walking speed had a statistically significant, moderate negative correlation with post-operative peak knee abduction moments [r(14) = -.558, p = .002] and peak knee power absorption [r(14) = -.548, p = .003], with pre-operative walking speed explaining 31% of the variability in peak knee abduction moment and 30% of the variability in peak knee power absorption.

Patient reported outcome measures (PROMs), such as the KOOS, do indicate the TKA is generally successful at relieving pain and show an overall improvement. However, their pre-operative values do not correlate with any biomechanical indicators of post-operative success, such as peak knee abduction moment and knee power. Shorter pre-operative TUG times and faster pre-operative walking speeds were correlated with improved post-operative biomechanical outcomes. These are simple tasks surgeons can implement into their clinics to evaluate their patients. Future research should expand these findings to a larger sample size and to determine if other factors, such as surgical approach or implant design, improves patient outcomes.

The Oxford mobile bearing knee prosthesis (Zimmer Biomet Inc, Warsaw, Ind) is considered a good treatment option for isolated medial compartment knee arthrosis. From February 2001 until August 2016, 1719 primary Oxford medial unicompartmental knee replacement procedures were completed at our center by a group of seven surgeons. We undertook this study to examine the long-term survivorship of the Oxford unicompartmental knee replacement looking at survivorship and reasons for failure.

A retrospective consecutive case series review was completed, and all revisions and re-operations were identified. Conversion to total knee replacement (TKA) was considered a failure. Kaplan-Meier survival analysis was used to calculate the 15-year survivorship of the group overall. We specifically looked at age, gender, BMI and surgeon caseload in addition to the reasons for failure. A statistical analysis was performed and differences in survivorship were compared for the variables listed. A logistic cox regression was performed to explore predictors of revision.

Overall 15-year survivorship was 89.9%. Female survivorship of 88.1% was statistically worse than the male group at 91.8% (p=0.018). Younger patients (75yrs of age (p= 0.036). There was a large range in surgical case load by individual surgeons (range 17–570 knees). There were no statistically significant differences in age, BMI, or gender when comparing the individual surgeon groups. There was a large range in 15-year survivorship between individual surgeons (range 78.3% – 95%). Overall the most common reason for revision was due to wear of the unreplaced portion of the knee (lateral and/or patella-femoral joint) followed by aseptic loosening, polyethylene dislocation, infection or persistent pain.

The 15-year survivorship results of the Oxford medial unicompartmental knee replacement at our center compares favourably to other published series and large registry data series. We found a reduction in survivorship in female patients and younger patients (< 5 5yrs). There were also significant differences in survivorship based on the individual surgeon. A more selective patient approach yielded the best long-term survivorship and equivalent to that of total knee replacement. We therefore suggest using a more selective approach when choosing patients for a medial unicompartmental knee replacement with the Oxford mobile bearing prosthesis in order to enhance long-term survivorship.

Integrated Regional Orthopaedic (MSK) Assessment clinics (ROAC) are now mandated in many provinces for the assessment and triage of patients referred for total joint arthroplasty (TJA). Their introduction underscores the lack of means for Primary Care Physicians (PCP) to appropriately refer patients for surgical consideration. Thus, problems arise when patients who are clear candidates for surgery are subject to a significant extra step in the care pathway by attending a ROAC while those who have insufficient problems are also seen, contributing to costs and crowding the access portal. We postulated that a patient reported outcome measure, decision aid combined with a validated grading of a weight bearing knee X-ray would provide an inexpensive yet effective tool to significantly improve the referral process for Knee OA (compared with the current mechanism).

To date we have enrolled two hundred and forty-five consenting patients to the study, all referred by their PCP to the ROAC with a diagnosis of symptomatic Knee Osteoarthritis. All patients were evaluated as per the current ROAC protocol which included a medical history, physical examination and an X-ray (standing AP, lateral and patella-femoral skyline). Prior to the visit, subjects were sent a copy of a patient decision aid, Oxford Knee Score (OKS) and requested to answer whether their current clinical status described as Patient Acceptable Symptom State (PASS2) was acceptable. All radiographs were analyzed and scored for OA severity using the validated grading from 0 – 13.

Of the 245 cases, 200 completed OKS and PASS2 uestionnaires and had standing X-rays for evaluation (only 120 completed the decision aid and these were left out of this report). Of the 200 included cases, 104 were referred from the ROAC to see a surgeon. In analysis, we found that a self-reported PASS 2 answer NO and an AP X-ray graded at 6 or above predicted over 75% of those patients that were referred. This represents a 3.4 greater likelihood of referral using this simple analysis. The OKS did not modify this prediction.

Thus, use of a validated grading of a standing AP X-ray along with a response, ‘readiness for surgery’ indicated 75% of patients appropriate for surgical consideration. Patients with less severe gradings are likely being unnecessarily referred to ROAC leading to overuse of scarce resources, crowding the access and adding to costs, others, who score higher, are being needlessly delayed. The ability to discreetly screen for the best possible candidates should be a continued focus of ROAC and will lead to improved use of expensive resources, overall patient care and satisfaction and the provision of tools to the PCP for appropriate referral.

Young, active patients with end-stage medial osteoarthritis (OA) secondary to anterior cruciate ligament (ACL) deficiency present a treatment challenge for surgeons. Current surgical treatment options include high tibial osteotomy (HTO) with or without ACL reconstruction, unicompartmental knee arthroplasty (UKA) with ACL reconstruction, and total knee arthroplasty (TKA). A recent systematic review reported a much higher rate of complications in HTO combined with ACL reconstruction than with UKA-ACL (21.1% vs 2.8%), while survivorship between the two procedures was similar. UKA offers several advantages over TKA, namely faster recovery, lower blood loss, lower rate of postoperative complications, better range of motion, and better knee kinematics. However, UKA has classically been contraindicated in the presence of ACL deficiency due to reported concerns over increased incidence aseptic loosening tibia. However, as a majority of patients presenting with this pathology are young and active, concerns about implant longevity with TKRA and loss of bone stock have arisen.

As a result, several authors have described combining ACL reconstruction with medial UKA to decrease the tibiofemoral translation-related stress on the tibial component, thereby decreasing aseptic loosening-related failures. The purpose of this study was to compare the functional outcomes and survivorship of combined medial UKA and ACL reconstruction (UKA-ACL) with those of a matched TKA cohort. We hypothesized that UKA-ACL patients would have better functional outcomes than TKA patients while maintaining similar survivorship.

Many patients who undergo a total knee arthroplasty (TKA) wish to return to a more active lifestyle. The implant must be able to restore adequate muscle strength and function. However, this may not be a reality for some patients as quadriceps and hamstrings muscle activity may remain impaired following surgery.

The purpose of this study was to compare muscle activity between patients implanted with a medial pivot (MP) or posterior stabilized (PS) implant and controls (CTRL) during ramp walking tasks.

Fifteen patients were assigned to either a MP (n=9) or PS (n=6) TKA operated by the same surgeon. Nine months following surgery, the 15 patients along with nine CTRL patients completed motion and EMG analysis during level, ramp ascent & descent walking tasks.

Wireless EMG electrodes were placed on six muscles: vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), semimembranosus (SM) muscles, gastrocnemius medial head (GM), and gastrocnemius lateral head (GL). Participants completed three trials of each condition.

EMG data were processed for an entire gait cycle of the operated limb in the TKA groups, and for the dominant limb in the CTRL group. The maximum muscle activity achieved with each muscle during the level trial was used to normalize the ramp trials. The onset and offset of each muscle was determined using the approximated generalized likelihood ratio.

Peak muscle activity (PeakLE), total muscle activity (iEMG), and muscle onsets/offsets were determined for each muscle for the ramp ascent and descent trials. Non-parametric Kruskal Wallace tests were used to test for statistical significance between groups with α=0.05.

During the ramp up task, both MP and PS groups had significantly greater PeakLE and iEMG for the hamstring muscles compared to the CTRL, whereas the PS group had significantly greater PeakLE compared with the MP group for the SM muscle.

During the ramp down task, both MP and PS groups had significantly greater PeakLE and iEMG for the SM and GL muscles compared to the CTRL. The PS group also had significantly greater iEMG for the BF and VM muscles compared to the CTRL. The MP group had a significantly earlier offset for the SM muscle compared to the CTRL.

Stability in a cruciate removing TKA is partially controlled by the prosthetic design. During the ramp up task, the TKA groups compensated the tibial anterior translation by activating their hamstrings more and for a longer duration. The MP group required less hamstrings activation than the PS group.

During the ramp down task, TKA patients stiffened their knee in order to stabilize the joint. The quadriceps, hamstrings and GL muscle were activated more and for a longer duration than the CTRL group to protect the tibial posterior translation. The PS group required greater BF and VM iEMG than the MP group.

Even if surgery reduced pain, differences in muscle activity exist between TKA patients and healthy controls. The prosthetic design provides some stability to the knee, and the MP implant required less muscle activation than the PS implant to stabilize the knee joint.

Introduction

Patients undergoing a total knee arthroplasty (TKA) are now living longer and partaking in more active lifestyles. They expect a high level of post-operative function and long term durability of their implant.

Using electromyography (EMG) analysis helps further explain biomechanical findings by giving insight as to what is occurring at the level of the muscles. Normal biomechanics are not restored post-TKA as patients have reduced knee flexion and weakened quadriceps muscles compared to their healthy peers.

An outpatient TKA program was developed by integrating advances in analgesia, rehabilitation, and minimally invasive surgical techniques with the objective of improving value in elective total knee arthroplasty (TKA) while maintaining quality standards. Previous studies have established the safety of outpatient TKA in selected populations, but the literature is devoid of outcome measures in these patients. Our goal was to investigate the quality of recovery, patient satisfaction, and safety profile in the first 90 days undergoing outpatient TKA.

One hundred TKAs in 93 consecutive patients with end-stage arthritis of the knee candidate for primary TKA were enrolled in this prospective matched cohort study. Patients that underwent inpatient TKA (47 TKAs) were compared with patients that underwent planned outpatient TKA (53 TKAs). The following 28 day post-operative scores were recorded: quality of recovery (QoR-18) and pain scores by Numerical Rating Scale (NRS-11). Satisfaction with pain control (0 to 10) and quantity of opioid use was collected. Secondary outcome measures of 90-day complications, readmissions, and emergency department (ED) visits were recorded.

Ninety-six percent of patients planned for outpatient TKA met our defined multidisciplinary criteria for same-day discharge. QoR-18 at post-operative day one was statistically higher in the outpatient TKA group. Otherwise, outcome measures were not statistically different between the 2 groups. Two patients required overnight admission: 1 for extended motor-block and 1 for vasovagal syncope. There were 7 ED visits in the in the outpatient group and 4 in the inpatient group. One outpatient was admitted for irrigation and debridement with liner exchange for an acute infection 2 weeks post-operatively. One inpatient required manipulation under anesthesia at six weeks post-operatively.

Outpatient TKA in selected patients produced a post-operative quality of recovery and patient satisfaction similar to that of inpatient TKA. Our results support that outpatient TKA is a safe alternative that should be considered due to its potential cost-savings and comparable recovery.

The purpose of this study was to compare lower limb joint mechanics in patients who underwent a total knee arthroplasty (TKA) with either a posterior stabilised (PS) or with a medial pivot (MP) implant to healthy controls (CTRL) during stair ascent and descent tasks.

Six PS (age: 67.2±1.5 years, BMI: 31.0±3.2 kg/m2) and 11 MP (age: 62.3±6.0 years, BMI: 29.7±3.9 kg/m2) TKA patients matched to 10 healthy CTRL participants (age: 65.6±5.5 years, BMI: 27.2±5.0 kg/m2) were included in the study. TKA patients went through 3D motion analysis after unilateral TKA with either a MP (11.7±3.4 months post-surgery) or PS (10.1±3.4 months post-surgery) implant performed using either a subvastus or medial parapatellar approach. Kinematic and kinetic data was collected using a 10-camera Vicon and two portable Kistler force plates placed on the first and second stair of a three-step staircase. Nonparametric Kruskal Wallace ANOVA tests were used and Wilcoxon rank sum tests were used to identify where significant (p < 0.05) differences occurred.

When comparing both stair tasks, stair ascent showed a larger number of significant differences in kinematic and kinetic variables than stair descent. Peak knee extension was significantly (p < 0.05) greater in both TKA groups compared to the CTRL during stair descent, whereas only the PS group had significantly (p = 0.02) greater knee extension angle than the CTRL during stair ascent. The PS group had a significantly (p = 0.01) lower peak knee extension moment than the CTRL group during both tasks and compared to the MP group during stairs ascent. During stair ascent, the MP group had significantly (p = 0.02) larger peak hip extension moments than both PS and CTRL group.

Greater knee extension angles in TKA groups at foot strike during stair tasks support the notion that TKA groups exhibit stiff knee during stance to reduce or avoid shear displacement on the operated knee. This could also result from many years of muscle adaptation waiting to receive a knee replacement. Reduced peak knee extension moment in the PS group during stairs tasks showed a quadriceps deficiency that could increase the risk of revision or of other joint replacement on the contralateral side or ipsilateral hip. MP group reproduced similar joint loading patterns as the CTRLs which may reduce their risk of revision. In conclusion, TKA patients continue to exhibit discrepancies from healthy knee mechanics during stair ascent and descent. Further research examining muscle function especially during stair ascent is warranted.

The Spine Adverse Events Severity System (SAVES) and Orthopaedic Surgical Adverse Events Severity System (OrthoSAVES) are standardised assessment tools designed to record adverse events (AEs) in orthopaedic patients. The primary objective was to compare AEs recorded prospectively by orthopaedic surgeons compared to trained independent clinical reviewers. The secondary objective was to compare AEs following spine, hip, knee, and shoulder orthopaedic procedures.

Over a 10-week period, three orthopaedic spine surgeons recorded AEs following all elective procedures to the point of patient discharge. Three orthopaedic surgeons (hip, knee, and shoulder) also recorded AEs for their elective procedures. Two independent reviewers used SAVES and OrthoSAVES to record AEs after reviewing clinical notes by surgeons and other healthcare professionals (e.g. nurses, physiotherapists). At discharge, AEs recorded by the surgeons and independent reviewers were recorded in a database.

AE data for 164 patients were collected (48 spine, 52 hip, 33 knee, and 31 shoulder). Overall, 98 AEs were captured by the independent reviewers, compared to 14 captured by the surgeons. Independent reviewers recorded significantly more AEs than surgeons overall, as well as for each individual group (i.e. spine, hip, knee, shoulder) (p2), but surgeons failed to record minor events that were captured by the independent reviewers (e.g. urinary retention and cutaneous injuries; AEs Grade 0.05). AEs were reported in 21 (43.8%), 19 (36.5%), 12 (36.4%), and five (16.1%) spine, hip, knee, and shoulder patients, respectively. Nearly all reported AEs required only simple or minor treatment (e.g. antibiotic, foley catheter) and had no effect on outcome. Two patients experienced AEs that required invasive or complex treatment (e.g. surgery, monitored bed) that had a temporary effect on outcome.

Similar complication rates were reported in spine, hip, knee, and shoulder patients. Independent reviewers reported more AEs compared to surgeons. These findings suggest that independent reviewers are more effective at capturing AEs following orthopaedic surgery, and thus, could be recruited in order to capture more AEs, enhance patient safety and care, and maximise different complication diagnoses in alignment with proposed diagnosis-based funding models.

The purpose of this study was to compare lower limb muscle activity in patients who underwent a total knee arthroplasty (TKA) with a medial pivot (MP) implant to healthy controls (CTRL) during a stair ascent task.

Seven MP (age: 61.4±6.5 years, BMI: 30.0±4.7 kg/m2, 12.4±3.8 months post-surgery) patients who underwent a TKA performed using either a subvastus or medial parapatellar approach were age- and BMI-matched to seven healthy CTRL participants (age: 62.4±4.2 years, BMI: 26.3±2.7 kg/m2) for comparison in this study. Participants underwent electromyography (EMG) analysis while completing a three-step stairs ascent task. Portable wireless surface EMG probes were placed on the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), biceps femoris (BF) and semimembranous (SM) muscles of both lower limbs. Peak linear envelope (peakLE) and total muscle activity (iEMG) were extrapolated and normalised to a maximal voluntary contraction. Nonparametric Kruskal Wallace ANOVA tests were used and Wilcoxon rank sum tests were used to identify where significant (p < 0.05) differences occurred.

The operated limb had significantly lower iEMG in the VAL, RF and BF muscles, and significantly lower peakLE in the SM muscle compared to the non-operated limb. The operated-limb of the MP group had significantly lower iEMG in the VAL and BF muscles, and significantly lower peakLE in the VAL, RF and SM muscles compared to the CTRL group. The non-operated limb in the MP group had significantly larger peakLE and iEMG in the RF muscle compared to the CTRL group.

Differences in muscle activity between the operated and non-operated limbs in TKA patients with a MP implant demonstrates a compensatory strategy to reduce loading on the operated limb by relying on the non-operated limb. This same strategy has been reported in other studies investigating other functional tasks. This reliance on the non-operated limb resulted by having greater peakLE and iEMG in the RF muscle compared to the healthy CTRLs. These differences between limbs could also result from many years of muscle adaptation waiting to receive a knee replacement. In conclusion, TKA patients exhibit discrepancies in muscle activity compared to healthy knees and differences between operated and non-operated limbs. Post-surgery rehabilitation should rely on unilateral strength exercises of the quadriceps and hamstrings muscles to reduce discrepancies to allow for a more balanced muscle activity between limbs.

Purpose

Patients with anterior cruciate ligament (ACL) deficiency and symptomatic medial compartment osteoarthritis (OA) present a challenge in management. These are often younger than typical primary OA patients and aspire to remain athletically active beyond simple ADLs. Combined ACL reconstruction and valgus tibial osteotomy (ACLHTO) is a well documented surgical option for patients deemed wither too young or too active for total knee arthroplasty. Unicompartmental knee arthroplasty (UKA) is an established surgical treatment for symptomatic medial osteoarthritis of the knee refractory to conservative management. A commonly cited contraindications is symptomatic ACL deficiency because of previous reports detailing premature failure through loosening of the tibial component. Improved results and endoscopic ACL reconstructive procedures have led to an enticing concept of combining ACL reconstruction with medial unicompartmental knee arthroplasty (ACLUKR) for those ACL-deficient medial osteoarthritic (OA) knees. We sought to compare the outcomes in 2 cohorts of patients who underwent either ACLHTO or ACLUKR for this clinical problem.

Purpose

Unicompartmental knee replacement (UKR) is an established, bone preserving surgical treatment option for medial compartment osteoarthritis (OA). Early revision rates appear consistently higher than those of total knee replacement (TKR) in many case series and consistently in national registry data. Failure with progression of OA in the lateral compartment has been attributed, in part, to surgical technical errors. In this study we used navigation assisted surgery to investigate the effects of improper sizing of the mobile bearing and malrotation of the tibial component on alignment and lateral compartment loading.