Above-Knee Amputation Following Chronically Infected Total Knee Arthroplasty: Patient-Reported Satisfaction and Functional Outcomes.

INTRODUCTION: Periprosthetic joint infection (PJI) that arises following total knee arthroplasty (TKA) can usually be resolved through surgical and antimicrobial therapy. However, in approximately 5% of cases, an infection that is chronic and persistent will require treatment by above-knee amputation (AKA). This study seeks to provide an enhanced understanding of patient functionality and satisfaction following this devastating complication of one of the most commonly performed surgeries in the world. METHODS: A retrospective chart review of all patients who underwent an AKA as a result of PJI following TKA at our center between January 2000 and November 2023 was performed. Patients completed a post-TKA AKA functionality and satisfaction questionnaire, as well as the 12-Item Short Form Survey (SF-12). Of 27 eligible patients, 14 were contacted by phone for follow-up, 6 were deceased, 6 could not be reached, and 1 declined participation. The mean age at AKA was 62 years old (range, 43 to 85). Patients had an average of 5.5 procedures (range, 3 to 8) between primary TKA and AKA. The average follow-up time post-AKA was 38.5 months (range, 12 to 102). RESULTS: Of the patients, 85.7% were satisfied with their AKA, 85.7% would choose AKA again, and 71.4% would have proceeded with AKA earlier in retrospect. Average SF-12 physical and mental component scores were 37.1 and 50.6, respectively. DISCUSSION: Despite important limitations in functional and ambulatory status, the vast majority of patients who underwent an AKA following an infected TKA are satisfied with their amputation and would choose this treatment modality again if necessary, with many indicating they would do so at an earlier time point. In light of these results, the option of amputation should, when medically indicated, be discussed in a sensitive, but timely manner with patients undergoing treatment for recalcitrant PJI.

Total Knee Arthroplasty Periprosthetic Joint Infection With Concomitant Extensor Mechanism Disruption and Soft-Tissue Defect: The Knee Arthroplasty Terrible Triad.

BACKGROUND: Periprosthetic infection (PJI) with concomitant extensor mechanism disruption (EMD) and soft-tissue defect-hereinafter termed the "Terrible Triad"-is a devastating complication following total knee arthroplasty. The purpose of this study was to define the surgical and clinical outcomes following management of a cohort of patients who have the Terrible Triad. METHODS: From 2000 to 2022, 127 patients underwent operative management for PJI alone, 25 for PJI with soft-tissue defects (defined as defects requiring flap reconstruction or being a factor contributing to the decision of performing above-knee amputation or arthrodesis), 14 for PJI with EMD, and 22 for the Terrible Triad. A composite outcome of infection status, range of motion, extensor lag, and ambulatory status at final follow-up was used to compare the proportion of patients in each group with a favorable overall knee outcome. Differences between groups were determined using one-way analyses of variance with post hoc Tukey's tests and Pearson's Chi-square tests or Fisher's exact tests with post hoc Bonferroni adjustments, where applicable. Odds ratios (OR) were calculated for comparison of the overall knee outcome between groups. A Kaplan-Meier survival analysis for patient mortality was performed. RESULTS: The mean follow-up was 8.4 years and similar between groups (P = .064). Patients who had the Terrible Triad had a 45.5% incidence of above-knee amputation, or arthrodesis, and an 86.4% incidence of an unfavorable outcome. Compared to patients in the PJI group, patients in the PJI who had a soft-tissue defect (OR = 5.8, 95% CI [confidence interval] 2.2 to 15.7), PJI with EMD (OR = 3.7, 95%CI 1.0 to 12.9), and Terrible Triad groups (OR = 11.6, 95% CI 3.3 to 41.5) showed higher odds of an unfavorable knee outcome. CONCLUSIONS: This study demonstrates that the total knee arthroplasty Terrible Triad is a dreaded diagnosis with poor outcomes. Clinicians and patients might consider early treatment with amputation or arthrodesis. LEVEL OF EVIDENCE: III.

Clinical applications of augmented reality in orthopaedic surgery: a comprehensive narrative review.

PURPOSE: The development of augmented reality (AR) technology allows orthopaedic surgeons to incorporate and visualize surgical data, assisting the execution of both routine and complex surgical operations. Uniquely, AR technology allows a surgeon to view the surgical field and superimpose peri-operative imaging, anatomical landmarks, navigation guidance, and more, all in one view without the need for conjugate gaze between multiple screens. The aim of this literature review was to introduce the fundamental requirements for an augmented reality system and to assess the current applications, outcomes, and potential limitations to this technology. METHODS: A literature search was performed using MEDLINE and Embase databases, by two independent reviewers, who then collaboratively synthesized and collated the results of the literature search into a narrative review focused on the applications of augmented reality in major orthopaedic sub-specialties. RESULTS: Current technology requires that pre-operative patient data be acquired, and AR-compatible models constructed. Intra-operatively, to produce manipulatable virtual images into the user's view in real time, four major components are required including a camera, computer image processing technology, tracking tools, and an output screen. The user is provided with a heads-up display, which is a transparent display, enabling the user to look at both their natural view and the computer-generated images. Currently, high-quality evidence for clinical implementation of AR technology in the orthopaedic surgery operating room is lacking; however, growing in vitro literature highlights a multitude of potential applications, including increasing operative accuracy, improved biomechanical angular and alignment parameters, and potentially reduced operative time. CONCLUSION: While the application of AR systems in surgery is currently in its infancy, we anticipate rapid and widespread implementation of this technology in various orthopaedic sub-specialties.

Reducing Acute Hospitalization Length of Stay After Total Knee Arthroplasty: A Quality Improvement Study.

BACKGROUND: The introduction of bundled funding for total knee arthroplasty (TKA) has motivated hospitals to improve quality of care while minimizing costs. The aim of our quality improvement project is to reduce the acute hospitalization length of stay to less than 2 days and decrease the percentage of TKA patients discharged to inpatient rehabilitation using an enhanced recovery after surgery bundle. METHODS: This study used a before-and-after design. The pre-intervention period was January to December 2017 and the post-intervention period was January 2018 to August 2019. A root cause analysis was performed by a multidisciplinary team to identify barriers for rapid recovery and discharge. Four new interventions were chosen as part of an improvement bundle based on existing local practices, literature review, and feasibility analysis: (1) perioperative peripheral nerve block; (2) prophylactic antiemetic medication; (3) avoidance of routine preoperative urinary catheterization; and (4) preoperative patient education. RESULTS: The pre-intervention and post-intervention groups included 232 and 383 patients, respectively. Mean length of stay decreased from 2.82 to 2.13 days (P < .001). The need for inpatient rehabilitation decreased from 20.2% to 10.7% (P = .002). Mean 24-hour oral morphine consumption decreased from 60 to 38 mg (P < .001). The percentage of patients experiencing moderate-to-severe pain and postoperative nausea and vomiting within the first 24 hours decreased by 25% and 15%, respectively (P < .001). Thirty-day emergency department visits following discharge decreased from 12.9% to 7.3% (P = .030). CONCLUSION: Significant improvements in the recovery of patients after TKA were achieved by performing a root cause analysis and implementing a multidisciplinary, patient-centered enhanced recovery after surgery bundle. LEVEL OF EVIDENCE: Level III.

Evaluation of the Medial Stabilized Knee Design Using Data From National Joint Registries and Current Literature.

BACKGROUND: Various designs of total knee arthroplasty (TKA) have provided satisfactory outcomes for the treatment of knee osteoarthritis for many years. The aim of the study is to evaluate the success and failure rate of the medial stabilized (MS) TKA design through national joint registries and the current literature. MATERIALS AND METHODS: A comprehensive literature review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses was carried out through PubMed and MEDLINE database. The international registries analyzed included the National Joint Registry, the Australian Orthopedic Association National Joint Replacement Registry, the Dutch Arthroplasty Register, the New Zealand Orthopedic Association Joint Registry, and the Michigan Arthroplasty Registry Collaborative Quality Initiative. We are reporting descriptive data which include means and percentages of survival rates and revision rates and number of years after the primary procedure. The revision rates and the cumulative revision rates are reported separately for each MS implant. RESULTS: Our detailed review identified 5 of 12 registries and 25 of 550 studies reporting on the survivorship of an MS TKA design. There were a total of 3684 procedures between the 25 studies, with an average survivorship free of aseptic loosening of 99% at 6.9 years. There are 26,693 (2.5%) MS TKAs in the current National Joint Registry with a mean cumulative revision rate of 2.63% at 5 years, 3.35% at 10 years, and 4.6% at 15 years. The Australian Orthopedic Association National Joint Replacement Registry provides survivorship data on 19,249 (2.9%) MS TKAs, with a mean cumulative revision rate of 3.34% at 5 years, 7.4% at 10 years, and 8.1% at 15 years. The Dutch Arthroplasty Register contains survivorship data on 1490 MS designs and a mean revision rate of these implants is 0.8% at 1 year, 5.95% at 5 years, and 9.8% at 10 years. The Evolution MP is the only implant reported in the Michigan Arthroplasty Registry Collaborative Quality Initiative and has a revision rate of 2.28% at 3 years. CONCLUSION: The MS TKA design has comparable results to traditional TKA designs across several joint registries and 25 studies in the literature.

The Effect of Polyethylene Liner Thickness on Patient Outcomes and Failure After Primary Total Knee Arthroplasty.

BACKGROUND: The effect of using thicker liners in primary total knee arthroplasty (TKA) on functional outcomes and aseptic failure rates remains largely unknown. As such, we devised a multicenter study to assess both the clinical outcomes and survivorship of thick vs thin liners after primary TKA. METHODS: A search of our institutional databases was performed for patients having undergone bilateral (simultaneous or staged) primary TKA with similar preoperative and surgical characteristics between both sides. Two cohorts were created: thick liners and thin liners. Outcomes collected were as follows: change in Knee Society Score (ΔKSS), change in range of motion, and aseptic revision. Ad hoc power analysis was performed for ΔKSS (⍺ = 0.05; power = 80%). Differences between cohorts were assessed. RESULTS: About 195 TKAs were identified for each cohort. ΔKSS and change in range of motion in the thin vs thick cohorts were similar: 51.4 vs 51.6 (P = .86) and 11.1° vs 10.0° (P = .66), respectively. No difference in aseptic revision rates were observed between thin and thick cohorts: all cause (4.1%, 3.1%; P = .59), aseptic loosening (0.5%, 0.5%; P = 1.0), instability (0.5%, 0.5%; P = 1.0), all-cause revision for stiffness (3.1%, 2.1%; P = .52), manipulation under anesthesia (2.1%, 2.1%; P = 1.0), and liner exchange (0.5%, 0%; P = .32). CONCLUSION: The results of this study suggest that both rates of revision surgery and clinical outcomes are similar for TKAs performed with thick and thin liners. Preoperative factors are likely to play an important role in liner thickness selection, and emphasis should be placed on ensuring sound surgical technique.

The Effectiveness of Repeat Two-Stage Revision for the Treatment of Recalcitrant Total Knee Arthroplasty Infection.

BACKGROUND: The gold-standard method in North America for the management of infected total knee arthroplasty is 2-stage revision arthroplasty. This has provided generally a high success rate. However, persistent infection after 2-stage revision knee arthroplasty does occur. The purpose of this study was to predict the success rate of second, 2-stage revision arthroplasty. METHODS: All infected total knee arthroplasty treated between 2000 and 2015 that were operated by a single senior surgeon were reviewed retrospectively. Patients were stratified according to general health and limb status according to the Musculoskeletal Infection Society (MSIS) scoring system. The reinfection rate at the last follow-up was identified. The chi-square test and Fisher exact test were used to compare binary variables. RESULTS: We found a statistical relationship between the higher stage of MSIS score, type of microorganism, flap surgery, and reinfection rate after reimplantation of second two-stage surgery. There is not any statistically significant correlation between age, gender, constraint pattern of prosthesis, number of spacers, and time interval between the first and second stages of second 2-stage surgery with the numbers available in this study. CONCLUSION: Another 2-stage knee revision is an effective method of treatment. However, we found a higher incidence of failure in those patients with poor general health based on the MSIS score, inadequate soft tissue envelope and resistant bacteria. The success of second, 2-stage protocol is best in patients with optimized general health, soft tissue coverage, and antibiotic-sensitive microorganism. Patients who cannot be optimized are most likely to require amputation or knee arthrodesis than another futile 2-stage surgery.

A Retrospective Comparison of a Medial Pivot and Posterior-Stabilized Total Knee Arthroplasty With Respect to Patient-Reported and Radiographic Outcomes.

BACKGROUND: Medial pivot (MP) type total knee arthroplasty (TKA) implants are designed with a highly congruent medial tibiofemoral articulation. Compared with the cam-and-post design of the posterior-stabilized (PS) TKA, the MP-TKA design has been hypothesized to better replicate the natural kinematics of the knee. We compared the MP-TKA and PS-TKA designs, with our primary outcome measures being range of motion (ROM) and patient-reported satisfaction. METHODS: This study was a retrospective comparison between the 2 groups (76 MP-TKA vs 88 PS-TKA). ROM was collected preoperatively, 6 weeks, 6 months, and 1 year postoperatively. The Forgotten Joint Score-12 (FJS-12) scores were collected at a minimum of 1 year postoperatively. RESULTS: There was no statistically significant difference in age, gender, or body mass index between the groups. We found a statistical difference in preoperative ROM (MP = 120.3°, PS = 112.8°, P = .002). There was no difference in ΔROM at 6 weeks (MP = -12.36, PS = -3.79, P = .066), 6 months (MP = -4.23, PS = 2.73, P = .182), or 1 year (MP = .17, PS = 3.31, P = .499). Patients who underwent the MP-TKA scored significantly better than the PS-TKA on the FJS-12 score (MP = 59.72, PS = 44.77, P = .007). CONCLUSION: We found that patients who underwent the MP-TKA scored better on the FJS than those who underwent the PS-TKA; particularly with regard to deep knee flexion and stability of the prosthesis. The MP-TKA design may offer improved patient outcomes because of its highly congruent medial tibiofemoral articulation.

Patient's Height and Hip Medial Offset Are the Main Determinants of the Valgus Cut Angle During Total Knee Arthroplasty.

BACKGROUND: Valgus cut angle (VCA), defined as the angle between the anatomical and the mechanical axes of femur, is an important parameter upon which a critical step of knee arthroplasty is based. Some variables have been proposed to affect the magnitude of this cut. However, little information is available regarding whether a generic value can be used, or if a patient-specific value from a long leg X-ray, or factors that can be determined preoperatively, is necessary to accurately set the VCA. METHODS: Standard standing 3-joint views were used to measure a number of anatomical measurements in 358 limbs, 202 patients (116 women, 86 men). Neck-shaft angle, medial offset, femoral length (FL), distal femoral articular angle, and VCA were measured. Demographic data including gender and height were extracted from hospital charts. The correlation of VCA with each of the other factors was evaluated using linear regression and t-test and finally multivariate analysis. RESULTS: The average VCA was 5.76° (range 4-8). Gender and distal femoral articular angle were not related to VCA (P = .343 and .995). FL was found to be a function of height with similar effects on multivariate analysis. Only the height (or FL) and femoral offset were identified as independent factors, with a negative correlation for the former (P < .001) and a positive correlation for the latter (P < .001). CONCLUSION: Femoral offset and height are the 2 independent factors determining VCA. Other parameters are indirectly related to these 2 factors. Tall patients with a small femoral offset have smaller VCA and short patients with a large offset have larger VCA. The wide variety of VCA values does not support using a generic value for all patients during knee arthroplasty.

Distal Femoral Arthroplasty for Management of Periprosthetic Supracondylar Fractures of the Femur.

BACKROUND: The incidence of periprosthetic supracondylar femoral fractures is 0.3% to 2.5% after primary total knee arthroplasty. METHODS: We performed a retrospective review 17 patients managed by distal femoral arthroplasty for periprosthetic supracondylar femoral fracture. RESULTS: Mean age was 76 years (SD, 12.58). Mean follow-up was 33.9 months (SD, 10.57). Mean final range of motion was 2° of fixed flexion (SD, 5.3) and flexion of 90.2° (SD, 20.8). Mean final follow-up Knee Society Score was 67.15 (SD, 19.7). Mean Short Form-12 physical component was 36.57 (SD, 11.2), and mean Short Form-12 mental component was 42.64 (SD, 12.09). Four complications (4 patients) were managed successfully without revision of the prosthesis. Two failures (2 patients) required prosthesis revision: patellar maltracking with knee dislocation, and periprosthetric femoral fracture. CONCLUSION: Distal femoral arthroplasty is a successful procedure. Complication rates are not insignificant, which is expected with the complexity of this clinical scenario.

The Use of a Closed-Suction Drain in Revision Knee Arthroplasty May Not Be Necessary: A Prospective Randomized Study.

BACKGROUND: The benefit of suction drains (SD) for the first 24-48 hours following joint replacement surgery is controversial. We aimed to determine if there is any difference in the early outcome of revision TKA when performed with, or without SD. METHODS: 83 cases indicated for revision knee arthroplasty were randomized to receive (42) or not receive (41) a deep intra-articlular drain. First-stage revisions for treating periprosthetic infection were excluded. Patients were statistically compared for demographic parameters, early complications and early knee functional outcome. The assessed outcomes included total blood loss, number of transfusions, fever and wound complication rate at 24 months follow-up. In addition, the change in knee society score at 12 weeks postoperatively was compared between the groups. RESULTS: There were no significant difference in demographic factors, wound complications, knee scores at 12 weeks and infection rate 24 months after surgery in either group. Average blood loss was 1856ml and 1533ml for the drain and no drain groups, respectively (P value=0.0470). The need for transfusion was significantly less in the no-drain group with an average of 0.15 unit/patient as compared to an average 0.37 unit/patient for the drain group (P value=0.0432). CONCLUSION: We were unable to find a point of superiority for using a drain for revision knee arthroplasty. Future studies with longer follow-up and larger population of patients are needed to make a valid conclusion.

Above knee amputation following total knee arthroplasty: when enough is enough.

In some cases, above knee amputation (AKA) for a chronically infected total knee arthroplasty is the only option. The purpose of this study was to assess patient satisfaction following AKA and to identify factors which may be indicative of successful outcome following AKA. A review was performed of 7 patients who underwent an AKA for a recurrent peri-prosthetic knee infection. Patient satisfaction was gauged through a modified questionnaire. All patients were satisfied with their AKA and 6 of 7 stated that they would have chosen an amputation earlier. Greater than 6 attempts at limb-salvage and failed gastrocnemius flap were identified by expert opinion as possible poor prognostic factors. Despite poor function, patients with chronically infected TKAs are satisfied following an AKA.

Effect of patellar thickness on knee flexion in total knee arthroplasty: a biomechanical and experimental study.

A biomechanical computer-based model was developed to simulate the influence of patellar thickness on passive knee flexion after arthroplasty. Using the computer model of a single-radius, PCL-sacrificing knee prosthesis, a range of patella-implant composite thicknesses was simulated. The biomechanical model was then replicated using two cadaveric knees. A patellar-thickness range of 15 mm was applied to each of the knees. Knee flexion was found to decrease exponentially with increased patellar thickness in both the biomechanical and experimental studies. Importantly, this flexion loss followed an exponential pattern with higher patellar thicknesses in both studies. In order to avoid adverse biomechanical and functional consequences, it is recommended to restore patellar thickness to that of the native knee during total knee arthroplasty.

Treatment of failed allograft prosthesis composites used for hip arthroplasty in the setting of severe proximal femoral bone defects.

This study assessed failures of allograft prosthesis composites (APC) and revisions with a new APC. Twenty-one patients with failed APC's after revision hip arthroplasty with severe proximal femoral bone loss underwent revision with a new APC. Causes of failure were aseptic loosening (18 patients), infection (3 patients). Of these 21 APC revisions, two patients failed (after 60, 156 months). The 5 and 10 year survival rates were 83.5% (95% CI, 79-100%, number at risk 12 and 6 accordingly). In addition, two patients had non-union at the host-allograft bone junction and were augmented with bone autograft and plate. These results suggest that failed APCs may be revised to a new APC with a predictable outcome.