Learning curve for active robotic total knee arthroplasty.

PURPOSE: Total Knee Arthroplasty (TKA) procedures incorporate technology in an attempt to improve outcomes. The Active Robot (ARo) performs a TKA with automated resections of the tibia and femur in efforts to optimize bone cuts. Evaluating the Learning Curve (LC) is essential with a novel tool. The purpose of this study was to assess the associated LC of ARo for TKA. METHODS: A multi-center prospective FDA cohort study was conducted from 2017 to 2018 including 115 patients that underwent ARo. Surgical time of the ARo was defined as Operative time (OT), segmented as surgeon-dependent time (patient preparation and registration) and surgeon-independent time (autonomous bone resection by the ARo). An average LC for all surgeons was computed. Complication rates and patient-reported outcome (PRO) scores were recorded and examined to evaluate for any LC trends in these patient related factors. RESULTS: The OT for the cases 10-12 were significantly quicker than the OT time of cases 1-3 (p < 0.028), at 36.5 ± 7.4 down from 49.1 ± 17 min. CUSUM and confidence interval analysis of the surgeon-dependent time showed different LCs for each surgeon, ranging from 12 to 19 cases. There was no difference in device related complications or PRO scores over the study timeframe. CONCLUSION: Active Robotic total knee arthroplasty is associated with a short learning curve of 10-20 cases. The learning curve was associated with the surgical time dedicated to the robotic specific portion of the case. There was no learning curve-associated device-related complications, three-dimensional component position, or patient-reported outcome scores. LEVEL OF EVIDENCE: Level II.

Active robotic technologies for total knee arthroplasty.

INTRODUCTION: When active robotic technologies for Total Knee Arthroplasty (TKA) were introduced over 20 years ago, broad usage of robotic technology was not felt to be needed as early data suggested no clear improvement in clinical outcomes compared to conventional techniques of implantation. Only recently has there been renewed enthusiasm for use of robotic technologies for implantation. MATERIALS AND METHODS: Active robotic technology specifically refers to the use of a robot for planning and executing the surgical procedure-with surgeon guidance and control. The physical work of bone preparation is performed by a milling tool, following a cut path defined by a CT-based preoperative plan. This manuscript describes the IDE experience of the only active robotic system (ARoS) available in the US, which took place from February 2017 through December 2018. RESULTS: 115 patients were enrolled in an IDE study to evaluate the safety and efficacy of an ARoS for TKA. No previously described safety issues for TKA occurred. Three-dimensional accuracy of component placement used the preoperative CT plan compared to the 3-months postoperative CT scan to demonstrate accuracy of all autonomous resections to within 1.5 mm and/or 1.5 degrees. Surgical planning and execution to restore alignment along kinematic principles were used in 40 procedures and to achieve mechanical alignment in 75 procedures. CONCLUSIONS: This FDA study of an active robotic approach for TKA represented the first multicenter trial and first US experience with this technology. Results demonstrated an excellent safety profile and high degree of accuracy. Advantages of this approach relate to standardization of the technique, multiple device options in the implant library, an excellent safety and accuracy profile, and consistency of results. Active robotics for TKA represents a viable and safe technique for primary TKA.

Techniques for periarticular infiltration with liposomal bupivacaine for the management of pain after hip and knee arthroplasty: a consensus recommendation.

Periarticular infiltration analgesia when used as a component of multimodal analgesia regimen has been shown to provide excellent pain relief after major joint replacement surgery. Recently, a liposomal formulation of bupivacaine (Exparel) has been approved for administration into the surgical site to produce postsurgical analgesia. It is a sustained release preparation of bupivacaine that has been shown to provide pain relief for up to 72 hours with a single local administration. Because the success of infiltration technique depends on systematic, extensive, meticulous tissue injection before surgical wound closure, a group convened to address the best practice for periarticular injection techniques for hip and knee replacement surgery. This article provides recommendations for optimal solution for injection (i.e., drug combinations or ``cocktail'' and total volume) as well as detailed description (including illustrations) of the infiltration technique for primary, revision, and unicompartmental knee arthroplasty and primary and revision hip arthroplasty using various surgical approaches.

Bilateral patellar component shear failure of highly cross-linked polyethylene components: report of a case and laboratory analysis of failure mechanisms.

A case of bilateral patellar component failure due to fatigue fracture of the all-polyethylene fixation pegs in a highly cross-linked ultra-high-molecular-weight polyethylene design is presented. To recreate this failure mode, a novel test method was developed to investigate the effects of peg orientation and cement technique on patella fatigue strength under cyclic compression and shear loading. Patellar peg orientation had a minor effect on shear strength, whereas lack of cement in the backside patellar groove had a substantial effect. The shear fatigue strength exceeded in vivo force estimates when the patellar groove was fully cemented. The test results and retrieval analysis suggest that high activity level and inadequate cement fixation of the patellar component may contribute to all-polyethylene patellar component peg fractures.

Safe and effective use of active robotics for TKA: Early results of a multicenter study.

BACKGROUND: A novel active robotic system for total knee arthroplasty (TKA) performs automated milling of bone surfaces. Study objectives were to assess system safety and effectiveness in a US population. METHODS: A multicenter clinical trial was conducted, following 115 patients for at least 6-months. A pre-defined list of robot-related adverse events was used to evaluate safety. Efficacy was assessed radiographically comparing planned versus achieved coronal limb alignment. RESULTS: No pre-defined adverse events occurred and postoperative limb alignment more than ±3° from plan occurred in 11.2 % of cases. CONCLUSION: Active robotics for TKA is safe and effective as demonstrated in this trial.

Early return to function after hip resurfacing: is it better than contemporary total hip arthroplasty?

Our hypothesis was that return of function for young patients undergoing resurfacing total hip arthroplasty (THA) with metal-on-metal bearings or contemporary THA with ceramic bearings would be comparable. Results from 337 unilateral hip resurfacing patients were compared with results from 266 unilateral ceramic-on-ceramic THA patients. Early differences in Harris Hip Scores were observed, but all differences faded by 24 months. Hip resurfacing seems to be a viable alternative to THA for well-selected patients. However, the public perception of improved functional capabilities was not demonstrated in this patient population. Resurfacing patients may be more impaired (slightly higher pain scores/lower function scores) than their THA counterparts in the early postoperative period, but these differences disappear by 24 months when both groups report Harris Hip Scores in the excellent range.

Accuracy and precision in resection alignment: Insights from 10,144 clinical cases using a contemporary computer-assisted total knee arthroplasty system.

BACKGROUND: Studies on total knee arthroplasty (TKA) with computer-assisted orthopedic surgery (CAOS) are limited by sample size or overlooked longitudinal performance of the system. This study aimed to assess resection accuracy across the entire TKA application history of a modern CAOS system considering multiple factors. METHODS: A retrospective analysis was performed based on a database that archives technical logs of all TKAs performed using a CAOS system. Coronal resection errors and percentage of outliers (<2° alignment error) in the proximal tibia and distal femur were assessed. Multilevel modeling was used to understand whether and where the resection error variability was located in the grouping categories, which included geographic region, individual established surgeon, preoperative alignment, adoption phase (learning/proficient), and version of the CAOS software application. RESULTS: A total of 10,144 cases were reviewed. The accuracy (mean) and precision (standard deviation) of the coronal alignment for both the tibia and femur were at the sub-degree level. High percentages of acceptable resections were observed across the pooled and each grouping category. The accountability for the amounts of total variability in tibial and femoral resection errors was negligible for all grouping categories, demonstrated by ICC values less than the common variations in observational studies. CONCLUSIONS: The study applied advanced analyses to assess alignment outcome in TKA bony resection alignment across the history of a specific CAOS system. The results demonstrated high resection alignment accuracy insensitive to geographic region, CAOS software application, adoption phase, preoperative alignment, and inter-surgeon differences.

Use of distraction loading to estimate subject-specific knee ligament slack lengths.

Knee ligaments guide and restrain joint motion, and their properties influence joint mechanics. Inverse modeling schemes have been used to estimate specimen-specific ligament properties, where external joint forces are assumed to balance with internal ligament and contact forces. This study simplifies this assumption by adjusting experimental loads to remove internal contact forces. The purpose of this study was to use novel experimental loading in an inverse modeling scheme to estimate ligament slack lengths, perform validation using additional loading scenarios, and evaluate sensitivity to the applied loading. Joint kinematics and kinetics were experimentally measured for a set of load cases. An optimization scheme used a specimen-specific forward kinematics model to estimate ligament slack lengths by minimizing the residual between model and experimentally measured kinetics. The calibrated model was used for a form of validation by evaluating non-optimized load cases. Additionally, uncertainty analysis related kinetic errors to previously reported kinematic errors. The six DOF tibial reactions realized RMS errors less than 23 N and 0.75 Nm for optimized load cases, and 33 N and 2.25 Nm for the non-optimized load cases. The uncertainty analysis, which was performed using the optimized load cases, showed average kinetic RMS errors less than 26 N and 0.45 Nm. The model's recruitment patterns were similar to those found in clinical and cadaveric studies. This study demonstrated that experimental distraction loading can be used in an inverse modeling scheme to estimate ligament slack lengths with a forward kinematics model.

What are the guidelines for the surgical and nonsurgical treatment of periprosthetic osteolysis?

Periprosthetic osteolysis is most often diagnosed by plain radiographs. Because these radiographs routinely underestimate the extent of the lesion, three-dimensional imaging should be used early in the evaluation process to confirm the presenting extent of disease. If the osteolytic process is asymptomatic, scheduled regular follow-up should be instituted until the lesion can be confirmed to be stable or until the decision is made to proceed with surgery. Nonsurgical management with pharmacologic agents has not proved to be effective. If surgery is contemplated, a three-dimensional evaluation with magnetic resonance imaging or helical computed tomography can assist in preoperative planning. Surgical intervention requires complete débridement of the lesional membrane and removal of the wear-generator--with or without component removal and with or without bone grafting, depending on the individual circumstances. A standardized follow-up evaluation mechanism for all patients should be a part of total joint arthroplasty management.

Physical therapy alone compared with core decompression and physical therapy for femoral head osteonecrosis in sickle cell disease. Results of a multicenter study at a mean of three years after treatment.

BACKGROUND: Osteonecrosis of the femoral head is a common complication in patients with sickle cell disease, and collapse of the femoral head occurs in 90% of patients within five years after the diagnosis of the osteonecrosis. However, the efficacy of hip core decompression to prevent the progression of osteonecrosis in these patients is still controversial. METHODS: In a prospective multicenter study, we evaluated the safety of hip core decompression and compared the results of decompression and physical therapy with those of physical therapy alone for the treatment of osteonecrosis of the femoral head in patients with sickle cell disease. Forty-six patients (forty-six hips) with sickle cell disease and Steinberg Stage-I, II, or III osteonecrosis of the femoral head were randomized to one of two treatment arms: (1) hip core decompression followed by a physical therapy program or (2) a physical therapy program alone. Eight patients withdrew from the study, leaving thirty-eight who participated. RESULTS: Seventeen patients (seventeen hips) underwent decompression combined with physical therapy, and no intraoperative or immediate postoperative complications occurred. Twenty-one patients (twenty-one hips) were treated with physical therapy alone. After a mean of three years, the hip survival rate was 82% in the group treated with decompression and physical therapy and 86% in the group treated with physical therapy alone. According to a modification of the Harris hip score, the mean clinical improvement was 18.1 points for the patients treated with hip core decompression and physical therapy compared with 15.7 points for those treated with physical therapy alone. With the numbers studied, the differences were not significant. CONCLUSIONS: In this randomized prospective study, physical therapy alone appeared to be as effective as hip core decompression followed by physical therapy in improving hip function and postponing the need for additional surgical intervention at a mean of three years after treatment.

Improving patient outcomes through advanced pain management techniques in total hip and knee arthroplasty.

Pain following orthopedic surgery is common and often suboptimally managed, with many patients reporting acute moderate to severe pain following surgery. Opioids are often used to manage this pain, yet this can result in significant side effects and complications, including constipation, nausea, vomiting, respiratory distress, and other central nervous system issues. Multimodal therapy that includes surgical site infiltration with extended release local anesthetic has been seen as a new way to minimize this pain for patients, which can result in improved quality of life and shorter length of hospital stay. This article examines the use of bupivacaine liposome injectable suspension (EXPAREL®; Pacira Pharmaceuticals, Inc., San Diego, California), a non-opioid product for pain management. Liposomal bupivacaine uses DepoFoam® technology that allows for the extended release of injected drugs. When used as the foundation of a multimodal regimen, it is effective in reducing postsurgical pain for up to 72 hours while reducing the need for opioids for pain relief.

Resurfacing arthroplasty for patients with osteonecrosis.

The suitability of third-generation metal-on-metal hip resurfacing products for patients with a primary diagnosis of osteonecrosis has been debated. The preservation of femoral head bone stock for femoral prosthetic support is essential for the long-term stability of implants. A modern hip resurfacing system was implanted in 1148 hips as part of a United States multicenter investigational device exemption study. Of these, 116 hips had a preoperative diagnosis of osteonecrosis and were compared to 1023 hips with osteoarthritis. Survival rates were not significantly different (95.9% and 95.8% at 24 months for osteoarthritis and osteonecrosis respectively, p = 0.46). Resurfacing arthroplasty for patients with osteonecrosis appears to be a reasonable alternative, taking into consideration implant size, patient gender, and size of femoral deficiency. Further characterization is needed to identify those specific patients with osteonecrosis for whom resurfacing arthroplasty would be appropriate.

Results and lessons learned from a United States hip resurfacing investigational device exemption trial.

BACKGROUND: Improvements in metal-on-metal bearings have made hybrid hip surface replacement a potential alternative for the young active patient with end-stage hip disease. Possible advantages include greater hip joint stability, bone preservation, and decreased osteolysis. In this study, we compared the clinical and radiographic results of a new resurfacing device with those in a historical group of standard total hip arthroplasties. METHODS: In 2001, the Cormet 2000 Hip Resurfacing Investigational Device Exemption study was initiated at twelve centers. A total of 337 patients treated with unilateral hip surface replacement with the Cormet device were enrolled in that study. These patients were compared with 266 patients in a previous study who had undergone unilateral total hip arthroplasty with ceramic bearing surfaces. Clinical and radiographic results were compared at similar time intervals. A newly recommended performance standard, the composite clinical success score, was used to assess non-inferiority of the hip resurfacing compared with the total hip arthroplasty used in the historical comparison population. RESULTS: At the time of follow-up, at a minimum of two years, the Harris hip scores were comparable between the resurfacing and total hip arthroplasty groups. Statistical evaluation of the composite clinical success scores confirmed the non-inferiority hypothesis. Revision was required in twenty-four patients in the resurfacing group and five patients in the total hip arthroplasty group. The most common cause of revision following resurfacing was failure of the femoral component (fracture of the femoral neck or loosening of the femoral component). CONCLUSIONS: Careful review of this study population revealed several important criteria for successful introduction of this resurfacing device into the United States. These include careful patient selection based on clinical and radiographic parameters and attention to various surgical details of implantation. These findings can be used to focus the training process for surgeons who wish to add implantation of this device to their surgical armamentarium. Such efforts should help to ensure safe and effective introduction of this new technology.

Blood management issues using blood management strategies.

Blood management strategies is a term used to address a coordinated approach to the management of blood loss in the perioperative period for total joint arthroplasty. The premise of any blood management strategy is that each patient, surgeon, and operative intervention experiences different risks of requiring transfusion, that those risks can be identified, and that a plan can be implemented to address them. A surgeon's decision to transfuse should be based on physiologic assessment of the patient's response to anemia and not on an arbitrary number ("transfusion trigger"). Intervention strategies can be applied preoperatively, intraoperatively, and postoperatively. Patient-specific planning allows for the appropriate use of patient, hospital, and system resources, ensuring that the consequences of anemia are minimized and that the patient's recovery process is optimized.

Computer-assisted surgery: a wine before its time: in opposition.

Total knee arthroplasty (TKA) surgery has achieved a high degree of success since the introduction of concepts of alignment and ligament balance in the early 1970s. Continuing pressure to improve function and longevity from the operative intervention has led to the design of increasingly sophisticated devices placed with the use of mechanical jigs. Although significant improvement has been made, errors of alignment and stability remain. Methods to diminish the margin of error have not been substantially improved with mechanical jigs, suggesting that intraoperative feedback is difficult to teach and learn, and resulting decision making is not as predictable as one would hope. This discussion will suggest why computer-assisted TKA may be the right answer to improving the predictability of TKA.

What would you do? Challenges in hip surgery.

The panel reviewed cases involving both revision and primary total hip arthroplasties. The panelists are Hugh Cameron and Allan Gross from Toronto, Charles Engh from Arlington, Aaron Rosenberg from Chicago, and Bernard Stulberg from Cleveland. The cases discussed brought up some controversial issues.

Clinical evaluation of avascular necrosis in patients with sickle cell disease: Children's Hospital Oakland Hip Evaluation Scale--a modification of the Harris Hip Score.

OBJECTIVE: To establish the validity and reliability of the Children's Hospital Oakland Hip Evaluation Scale (CHOHES), a modification of the Harris Hip Score, for the evaluation of avascular necrosis (AVN) in sickle cell disease (SCD). DESIGN: Nonrandomized test-retest. SETTING: Outpatient clinic. PARTICIPANTS: Forty patients with SCD and 3 healthy controls participated. Twenty-six SCD patients (15 males, 11 females; mean age, 25 y) had been diagnosed with AVN. This group was compared with 14 SCD patients without AVN and 3 healthy controls (8 males, 9 females; mean age, 16 y). INTERVENTION: On average, subjects were assessed by 2 physical therapists by using the CHOHES on 3 separate outpatient visits within a 2-week period. MAIN OUTCOME MEASURES: A mixed model with random effects was constructed to compare patient scores on the CHOHES with disease severity as estimated by Ficat staging on plain radiographs. Correlations between and within physical therapists using the CHOHES were calculated to assess intra- and interrater reliability. RESULTS: From the random effects model, the CHOHES mean score was 88 for Ficat stage 0, 75 for Ficat stage I or II, and 61 for Ficat stages III or IV (P < .05). Intrarater reliability estimates for the total CHOHES score were very good (r > or = .87) as were interrater reliability estimates (r > or = .90) between therapists who measured hips with a wide range of CHOHES scores. CONCLUSIONS: The CHOHES appears to be an easy-to-use, valid, and reliable assessment tool and should be considered for use in the routine clinical evaluation of SCD patients with AVN.

Osteonecrosis: what to do, what to do!

Despite extensive literature on the subject, the treatment approaches for osteonecrosis of the femoral head (ONFH) remain controversial. The literature presently available to the orthopaedist suggests that i) ONFH can be identified early; ii) there are reasonable treatments for early stages of ONFH; iii) no single treatment is sufficient for all hips; and iv) there is as yet no predictable permanent treatment for early ONFH. The author's recommended approach for the practicing orthopaedist includes the following: i) develop a high degree of clinical suspicion that the disease is present and understand the role of magnetic resonance imaging in making an accurate diagnosis; ii) understand and use an appropriate staging system for each hip diagnosed; iii) be comfortable with several treatment options for early ONFH or choose to refer to appropriate centers; and iv) become comfortable with the use of uncemented THA for end-stage ONFH. The field continues to need and should support better treatment studies, including randomized clinical trials.