Total Joint Arthroplasty

Title XVIII of the Social Security Act, §1862 (a)(1)(A) allows coverage and payment for only those services that are considered to be reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of a malformed body member.

Title XVIII of the Social Security Act, §1862 (a)(1)(D) Items and services related to research and experimentation.

Title XVIII of the Social Security Act, §1862 (a)(7) states Medicare will not cover any services or procedures associated with routine physical checkups.

Title XVIII of the Social Security Act, §1833 (e) prohibits Medicare payment for any claim which lacks the necessary information to process the claim.

42 CFR §410.32 indicates that diagnostic tests may only be ordered by the treating physician (or other treating practitioners acting within the scope of his or her license and Medicare requirements).

CMS Internet-Only Manual, Pub 100-03, Medicare National Coverage Determinations Manual, Chapter 1, Part 4, Section 220.

The Protecting Access to Medicare Act (PAMA) of 2014, Section 218(b), established a new program to increase the rate of appropriate advanced diagnostic imaging services provided to Medicare beneficiaries.

42 CFR §414.92 codifies the Appropriate use Criteria Program policies.

CMS Clinical Endpoints Guidance: Knee Osteoarthritis

Total Knee Arthroplasty

Primary total knee arthroplasty is considered reasonable and medically necessary if all of the following criteria have been met (1,2,3,4 and 5):

1. Advanced joint disease;^1-4

1. 1. Osteoarthritis with joint destruction^1-4 OR
   2. Avascular necrosis (osteonecrosis)⁵ OR
   3. Inflammatory arthritis when intractable to medical management² OR
   4. Traumatic with joint destruction (distal femur fracture, proximal tibia fracture)⁶ OR
   5. Tumor (malignant and non-malignant) with joint destruction affecting the femur, proximal tibia, knee joint of adjacent soft tissues^2,7 OR
   6. Failed osteotomy or unicompartmental knee arthoplasty⁸

2. Moderate to severe pain and loss of function using standardized pain and function scales* for assessment;⁹

3. Radiographic findings demonstrating advanced arthritic changes;¹

1. 1. X-ray assessments consistent with advanced arthritic changes i.e. a score of ≥2 on the Kellgren–Lawrence scale, with scores ranging from 0 to 4 and a score of ≥2 indicating definite osteoarthritis^3,9 OR
   2. Alternative radiographic measures (such as MRI or CT) when conventional radiographs are not adequate.

4. A trial of at least 1 or more conservative therapy without improvement in pain and function typically for a duration of a minimum of 3 months. In exceptional circumstances when conservative therapy is determined to not be appropriate, rationale must be documented in the medical record; ^10-12

5. Optimization of co-morbidities if applicable

1. Documentation of smoking history, and counselling on the effect of smoking on healing. Treatment for smoking cessation and outcome of counselling, if applicable.
2. For patients with diabetes documentation of counseling of risk and efforts to optimize medical management and reduce blood sugars if applicable
3. For obesity, risk counseling and efforts for weight reduction to optimize outcomes documented.

Revision or replacement

Revision or replacement TKA will be considered medically necessary if:

1. Documentation as to the cause of the failure of the primary procedure (such as infection, aseptic loosening , periprosthetic fracture, instability, moderate to severe pain and loss of function using standardized pain and function scales for assessment, polyethylene wear, restriction of motion/arthrofibrosis, extensor mechanism insufficiency, implant failure, and allergy).¹³

AND

2. Modifiable factors are addressed prior to surgical intervention.

Total Hip Arthroplasty

Primary total hip arthroplasty is considered reasonable and medically necessary if all of the following criteria have been met (1,2,3,4&5):

1. Advanced joint disease;

1. 1. Osteoarthritis with joint destruction^1-4 OR
   2. Avascular necrosis of the hip (osteonecrosis of femoral head)^14,15 OR
   3. Femoroacetabular impingement syndrome¹⁶ OR
   4. Developmental hip dysplasia or childhood hip disorders¹⁴ OR
   5. Fracture of the femoral neck¹⁵ OR
   6. Non-union or failure of previous hip fracture or malunion of acetabular or proximal femur fracture¹⁴ OR
   7. Malignancy of the joint involving the bones or soft tissue of the pelvis or proximal femur¹⁴
   8. Acetabular fracture¹⁴

2. Moderate to severe pain and loss of function using standardized pain and function scales* for assessment;⁹

3. Radiographic findings demonstrating advanced arthritic changes;¹

1. 1. X-ray assessments consistent with advanced arthritic changes e., a score of ≥2 on the Kellgren–Lawrence scale, with scores ranging from 0 to 4 and a score of ≥2 indicating definite osteoarthritis;^3,9 OR
   2. Alternative radiographic measures (such as MRI) when conventional radiographs are not adequate

4. A trial of at least 1 or more conservative therapy without improvement in pain and function typically for a duration of a minimum of 3 months. In exceptional circumstances when conservative therapy is determined to not be appropriate, rationale must be documented in the medical record.^11,12

5. Optimization of co-morbidities if applicable

1. 1. Documentation of smoking history, and counselling on the effect of smoking on healing. Treatment for smoking cessation and outcome of counselling, if applicable.
   2. For patients with diabetes documentation of counseling of risk and efforts to optimize medical management and reduce blood sugars if applicable
   3. For obesity, risk counseling and efforts for weight reduction to optimize outcomes documented.

Revision or replacement

Revision or replacement THA will be considered medically necessary if:

1. Documentation as to the cause of the failure of the primary procedure (such as instability, aseptic loosening, osteolysis and/or wear, infection, periprosthetic fracture, implant fracture, failed bipolar, periprosthetic bone loss, fracture, mechanic failure, and dislocation)¹⁷ AND

2. Modifiable factors are addressed prior to surgical intervention.

Limitations

TJA should not be performed in presence of:

1. Local or systemic active infection
2. Neuropathic arthritis
3. Rapidly progressive neurological disease
4. Skeletal immaturity
5. Quadriplegia
6. Permanent or irreversible muscle weakness in the absence of pain

Bilateral Surgery

When bilateral TKA or bilateral THA is performed, the criteria listed above and documentation requirements below apply to each joint upon which surgery is performed.

This local coverage determination (LCD) is only addressing medical necessity criteria for performing total knee and hip replacement surgery. The indications in this LCD are not to be applied for unicompartmental knee replacement surgery which is only contained to one compartment of the knee. However, failed previous unicompartmental joint replacement is an indication for performing TKA.

The devices/implants for total knee and total hip replacement surgeries are regulated by the FDA as medical devices. The devices used should be class II or class III devices that meet the requirements as outlined in the CFR, Title 21, Volume 8, Chapter I, Subchapter H, Part 888 Orthopedic Devices.

Definitions

Total Joint Arthroplasty (TJA) replacement of the joint with an endoprosthesis or implant.

Total Knee Arthroplasty (TKA) also referred to as total knee replacement is a surgical procedure in which the diseased articular surface of the knee is resected followed by resurfacing with prosthetic components.²

Total hip Arthroplasty (THA) also referred to as hip replacement is a surgical procedure in which the diseased portion of the hip is resected followed by artificial components.

Conservative therapy- nonsurgical management which includes may physical therapy, non-steroidal anti-inflammatory drugs (NASIDS), braces, intraarticular injections, weight reduction, and smoking cessation.⁹

Grading of Recommendations Assessment, Development and Evaluation (GRADE)- widely recognized system for assessing the quality of evidence and the strength of recommendations in healthcare.¹⁸

*Scales¹⁹

Standardized pain scales should be used for the evaluation. The specific scales are at the discretion of the provider but examples of standardized scales include but are not limited to:

• EuroQol-5 Dimension (EQ-5D)
• Hanover Functionality Status Questionnaire (FFbH)
• Harris Hip Score (HHS)
• Hip Disability and Osteoarthritis Outcome Score (HOOS)
• Hospital for Special Surgery Knee Score
• Insall Knee Score
• Knee Injury and Osteoarthritis Outcome Score (KOOS)
• Knee Society Score
• Numerical Rating Score (NRS)
• Oxford Knee questionnaires/ Oxford Hip Score
• Timed up-and-go test to assess
• Western Ontario and McMaster Universities (WOMAC) questionnaire
• Visual Analog Scale (VAS)
• 40-meter walk test, 30-second chair test, stair-climb test and six-minute walk test

Literature Search

A literature search was conducted using the following key words: total knee arthroplasty; total hip arthroplasty, total joint arthroplasty, unicompartmental knee arthroplasty, robotic-assisted, computer aided navigation, revision. The literature search was filtered to identify articles within 5-10 years, English language, full-text articles, clinical trials, and systematic reviews/meta-analyses (SR/MA). In general, improved health outcomes of interest include patient quality of life and function.

Evidence was analyzed to address the certainty of evidence that the change in outcome is due to the product being investigated and improves patients’ outcomes. Case reports, case series and retrospective reports were not reviewed for product coverage due to low certainty evidence but used as an adjunctive measure for other aspects pertinent to this subject. Review papers, editorials, cost analysis and unpublished reports were not included in the analysis.

Background

Total knee arthroplasty is one of the most performed orthopedic procedures with an exponential increase in volume in the Medicare population. Joint OA (of any joint) is estimated to affect 32.5 million adults in the US. The incidence of knee OA in the United States is estimated at 240 persons per 100,000 per year.²⁰ The most common cause for total joint replacement is osteoarthritis followed by avascular necrosis, inflammatory disease and trauma.¹⁵

Conservative management

Studies demonstrate conservative measures may improve pain and function for OA. A Cochrane review identified 54 studies evaluating land based therapeutic exercise with a non-exercise control for knee OA. Pooled results of 44 trials indicated a significant reduction in pain with exercise (12 points/100; 95% CI: 10-15) and physical function (10 points/100; 95% CI: 8-13). The authors conclude that land based therapeutic exercise provides short term benefits sustained for at least 2 to 6 months after cessation of formal treatment.²¹ Strengthening exercises have been recommended by the American College of Rheumatology as a treatment for knee osteoarthritis.^10,11 The duration of time for conservative therapy has been subject to debate, but 3 months is typically tried before intervention in most reports.

An observational cohort study evaluated 183 patients with knee and/or hip OA. Numerical rating scale was utilized to assess pain with a goal of NRS ≤4. Patients were managed with a combination of analgesia and evidence-based multimodal conservative treatment. The authors reported success in 47% of the conservatively managed patients and could not discern factors to predict those which would be successful. They recommended a trial of conservative treatment prior to referral for surgery.¹²

Osteoarthritis

Osteoarthritis (OA) can cause significant pain and morbidity and is the leading cause of total joint arthroplasty of the knee and hip accounting for 90-97% of TKAs.²² Conservative measures including physical therapy, non-steroidal anti-inflammatory drugs, braces, interarticular injections and weight reduction are first line management. When these treatments have failed defined as progressive pain and loss of function surgical management may be considered.⁹ There has been a steady increase in TJA in the United States.

A systematic review evaluated indications for criteria in TKA and THA in osteoarthritis.¹ The review of 6 guidelines and 18 papers conclude that indications for surgical management are based on limited evidence with large heterogeneity and call for further research to develop optimal patient selection and timing for positive patient outcomes. Studies on appropriateness of criteria for THA/TKA showed 20-45% of cases were considered uncertain and are associated with lower satisfaction rates.

A randomized controlled trial (RCT) of 100 patients with moderate to severe knee OA eligible for TKA were randomized to surgical treatment followed by 12 weeks of non-surgical treatment or 12 weeks of non-surgical treatment alone and followed for 1 year.³ The primary outcome was the change from baseline to 12 months in the mean score on 4 using KOOS subscales covering pain, symptoms, activities of daily living, and quality of life at 3, 6 and 12 months. At 12 months, 95 subjects completed the study and 13 in the non-surgical arm underwent TKA prior to the 12-month follow-up. In the intention to treat analysis the TKA group had greater improvements in KOOS score than the non-surgical treatment group (32.5 vs. 16.0; adjusted mean difference, 15.8 [95% confidence interval, 10.0 to 21.5]), while the surgical group had a higher number of serious adverse events (24 vs. 6, P = 0.005). The authors conclude TKA followed by non-surgical treatment is superior to non-surgical treatment alone in providing pain relief and improved function at 12 months in patients with moderate to severe osteoarthritis. Limitations of the study include potential risk of bias due to lack of description of randomization method, lack of generalizability, and mean age below the Medicare population.

The Ulm Osteoarthritis Study was a prospective cohort study of 706 patients undergoing total joint replacement for osteoarthritis of the knee or hip. Patients were followed for 12 months post-surgery and evaluated for risk of long-term mortality. The authors reported that the arthroplasty was accompanied by a clear reduction in pain and improvement in function throughout all assessments (WOMAC, FFbH and VAS). An independent increase in the risk of mortality was found with generic function assessment with hazard ratio of 1.79 (95% CI 1.24-2.60). The authors conclude that patients with poor baseline function, assessed with FFbH assessment, have an increased risk of long-term survival as compared to those without impairment prior to surgery.⁴

Avascular Necrosis

Avascular necrosis or osteonecrosis is degenerative disease is death of the cellular components of sub chondral bone due to ischemia which can lead to joint destruction. This most commonly affects the hip, and less commonly the knee, shoulder, and ankle. Primary (spontaneous and idiopathic) occurs without associated risk factors while secondary is associated with risk factors such as steroid and alcohol use, obesity and other comorbidities and chondral damage from knee arthroscopy. Conservative management is the recommended first line therapy with joint preservation, in severe cases that are refractory to conservative measures may be considered TKA.⁵

Inflammatory arthritis with joint destruction

Inflammatory arthritis such as rheumatoid, gout, psoriatic, spondylarthritis and other inflammatory arthritides can result in knee joint destruction with pain and disability.² Improvement management of the underlying conditions with disease-modifying antirheumatic drugs have reduced the need for surgical intervention in this population.²³ However, RA patients may develop osteoporosis and ligament relaxation with joint deformity and TKA offers an effective treatment option in these cases.²³

A systematic review and meta-analysis compared the outcomes for TKA in patients with OA compared to RA. Twenty-four articles met inclusion criteria with 8,033,554 patients included and followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Newcastle-Ottawa scale (NOS) for methodology assessment.²³ The results conclude strong evidence for increased risk of overall infection (OR = 1.61, 95% CI, 1.24–2.07; P = 0.0003), deep infection (OR = 2.06, 95% CI, 1.37–3.09; P = 0.0005), VTE (OR = 0.76, 95% CI, 0.61–0.93; P = 0.008), pulmonary embolism (PE) (OR = 0.84, 95% CI, 0.78–0.90; P<0.00001), periprosthetic fractures (OR = 1.87, 95% CI, 1.60–2.17; P<0.00001); and reasonable evidence for increased risk of deep venous thrombosis (DVT) (OR = 0.74, 95% CI, 0.54–0.99; P = 0.05), and length of stay (OR = 0.07, 95% CI, 0.01–0.14; P = 0.03) after TKA in patients with RA versus OA. There were no significant differences in superficial site infection, revision, prosthetic loosening, or mortality. The authors conclude that despite the increased risk TKA is an effective surgical procedure for patients whose conditions are refractory to conservative and medical management of RA. The meta-analysis is challenged by lack of randomized controlled trials, risk of confounding, small sample size and variables in included studies, moderate to high heterogeneity of included studies (I²⁼ 49-96%), and some studies were older and do not represent modern surgical techniques. Due to most included studies being retrospective this report represents low-quality literature.

The National Inpatient Sample (NIS) database was used to compare the demographic characteristics, and morbidity and mortality for TKA in patients with RA to those with OA with 1:1 propensity match. The analysis found that 4.3 % (6363/132,405) of those undergoing TKA had RA and they reported they did not have increased odds of complications or in hospital mortality as compared to those with OA.²⁴

Inflammatory arthritis is an uncommon indication for THA in absence of joint destruction from other causes.¹⁵ A population based comparative study of 68,348 patients who underwent THA within a national private insurance database were evaluated.²⁵ Patients with inflammatory arthritis represented 2.12% (n=3254) of those undergoing THA in this population and were found to have significantly higher risk of transfusion, mechanical complications, infection and readmission following THA.

Others

Post-traumatic degenerative joint disease (accidents/sports-injuries), sequalae of infection, congenital joint abnormalities, malignancies, and direct joint damage from radiation may be causes for joint destruction.²

A systematic review included 16 studies, 4 prospective and 10 retrospectives, in patients who underwent TKA for post-traumatic arthritis (PTA) after fractures of the proximal tibia, patella and or distal femur. All studies reported improved functional outcomes. The Knee Society Scale was reported for 11/16 with improvements. Complications included in infection, stiffness, wound complications, interoperative rupture of tendons and osteolysis polyethylene wear within the first two years of surgery. Compared to OA revision was more common for PTA with majority due to polyethylene wear.⁶

Congenital dislocation of the patella is a rare condition usually in children and affected knees may develop valgus deformity and osteoarthritis. There is a paucity of literature exploring this condition; however, case series and case reports have demonstrated the effectiveness of TKA in extreme cases to improve the patient's ability to walk and pain. In most cases other repairs are done rather than TKA. Congenital hip dysplasia and childhood hip disorders (e.g., Legg-Calvé-Perthes disease, slipped capital femoral epiphysis) have shown improvement after THA in cases of joint destruction.¹⁴

Tumors of the knee can require resection of the portions of the knee for management. Total knee arthroscopy may be utilized for reconstruction in these cases. Malignancy is the most common indication for TKA patients <21 years old.⁷

A systematic review and meta-analysis compared conservative management to THA for femoroacetabular impingement syndrome (FAIS).¹⁶ This condition is caused by impingement between the femur and acetabulum during movement of the hip and usually occurs in young adults. Fifty-two articles, including 3 RCTs, were included. The authors concluded that THA resulted in improvements in quality of life (3 trials, 575 participants, ES = 2.109, 95% CI: 1.373 to 2.845, I² = 42.8%, P = 0.000) and activity of daily living (2 trials, 262 participants, ES = 9.220, 95% CI: 5.931 to 12.508, I² = 16.5%, P = 0.000), but not sports function (2 trials, ES = 7.562, 95% CI: -2.957 to 18.082, I² = 60.1%, P = 0.159) as compared to conservative treatment.

Modifiable risk factors (obesity/smoking/diabetes)

A systematic review and meta-analysis evaluated the impact of smoking on TKA outcomes. Thirteen papers were included in the review. The authors conclude that smoking increases the risk of complications from TKA. Smoking increased risk of post-operative pneumonia (summary RR = 1.31, 95% CI [1.06, 1.63], p = 0.01, deep wound infection (summary RR = 2.05, 95% CI [1.43, 2.94], p < 0.01), superficial wound infection (summary RR = 2.39, 95% CI [1.26, 4.56], p < 0.01), and increased risk of revision/removal of components ((summary RR = 1.31, 95% CI [1.06, 1.63], p = 0.01) due to infection.²⁶ The data is limited by high heterogeneity that precluded meta-analysis, use of cohort studies and overall small sample sizes limiting data quality.

A systematic review and meta-analysis explored the impact of diabetes on THA and included 39 studies. The investigators reported higher rates of periprosthetic joint infection (OR: 1.71, 95% confidence interval [CI]: 1.46–2.00, p < 0.01), prosthesis revision (OR: 1.37, 95% CI: 1.23–1.52, p < 0.01), pneumonia (OR: 1.54, 95% CI: 1.15–2.07, p < 0.01), urinary tract infection (OR: 1.86, 95% CI: 1.07–3.26, p = 0.02), sepsis (OR: 1.61, 95% CI: 1.46–1.78, p < 0.01), and post-operative cardiovascular (OR: 2.49, 95% CI: 1.50–4.17, p < 0.01) and cerebrovascular (OR: 2.38, 95% CI: 1.48–3.81, p < 0.01) events.²⁷ While they found the risk of deep vein thrombosis (OR: 1.58, 95% CI: 1.22–2.04, p < 0.01) increased they did not find increase risk of pulmonary embolism. Significantly, diabetics had a higher mortality rate within 30 days after TKA (OR: 1.27, 95% CI: 1.02–1.60, p = 0.03).

The American Academy of Orthopedic Surgeons (AAOS) Diagnosis and Prevention of Periprosthetic Joint Infections Clinical Practice Guideline report moderate strength evidence supports that obesity is associated with increased risk of periprosthetic joint infection (PJI).²⁸ Limited strength evidence suggest diabetes and uncontrolled diabetes is a risk factor for PJI after THA or TKA.

Revisions

There is little evidence on revision or replacement procedures for TKA or THA. Retrospective data reports the most common reasons for revision or replacement include instability (16%), aseptic loosening (45%), osteolysis and/or wear (16%), infection (11%), periprosthetic fracture (6%) and other rare causes (7%).¹⁷ Further research is needed to determine how indications for surgery, patient factors, surgical approach and implant types impact the need for future revision.

Most hip replacements require no further surgery, but in a retrospective review of 1100 revisions of THAs a rate of 13% underwent a second revision. Of these 70% were for a diagnosis different than the original indication for surgery and 30% for the same diagnosis as index revision.¹⁷ Reasons for failure include: instability (35%), aseptic loosening (30%), osteolysis and/or wear (12%), infection (12%), periprosthetic fracture (2%) implant fracture (1.5%), others (0.04%), failed bipolar (.01%).

A prospective report of 312 patients who underwent 402 revision TKA reported that infection (36.1%), aseptic loosening (21.9%) and periprosthetic fracture (13.7%) were the leading causes for revision.¹³ Additional causes for revision included instability (6.7%), pain (6%), polyethylene wear (5.2%), restriction of motion/arthrofibrosis (4.5%), extensor mechanism insufficiency (3.7%), implant failure (2%), and allergy (0,2%). Overall revision rates were low with about 5% of cases undergoing revision and more than 1 revision being uncommon.

Using multi-institutional database revision TKAs over 8 years (n= 1054) were evaluated. Body mass index was divided into nonobese (BMI 18.5 to 29.9), obese (BMI 30 to 39.9), and morbidly obese (BMI >/= 40) and found obese and morbidly obese patients had a significantly higher risk for repeat revision surgery compared to normal weight individuals. The most common reason for revision was dislocation which was 4 times more likely in the morbidly obese population and obesity was found to be an independent risk factor for implant loosening in the primary TKA setting.²⁹

Another retrospective report stated BMI did not impact revision rate in 1059 patients who underwent primary TKA. There were 41 revisions (3.9%) and BMI did not affect the risk of revision when adjusted for relevant covariates in a multivariate logistic regression analysis (odds ratio 0.99, 95% confidence interval 0.93-1.05, P = 0.6). Limitations include retrospective design, variable duration of follow-up and missing data.³⁰

Computer-assisted navigation

Computer-assisted navigation (CAN) in musculoskeletal procedures describes the use of computer-enabled tracking systems to facilitate alignment in a variety of surgical procedures. There is image based and non-image-based devices. This technology has been used in many different types of procedures, but most commonly in orthopedic total knee arthroplasty (TKA) and hip arthroplasty (THA). Potential benefits of navigation include possible improvement in accuracy of the implant position and disadvantages include increased operative time, need for image acquisition preoperatively or intraoperatively and increase cost.¹⁴

The Nationwide Inpatient Sample database was used to identify 6,060,901 patients who underwent TKA, of which 273,922 (4.5%) used computer navigation and 24,084 (0.4%) robotic assistance. The technology increased from 1.2% in 2005 to 7% in 2014 in the United States accompanied by an increase in hospital charges associated with the use of the technology assistance.³¹

A report using a Medicare database to compare CAN to conventional approach for THA between 2005 to 2012 reported on 64,944 THA of which 5412 used CAN. CAN did not lower rate of dislocation at 30 days (1.0% vs 1.2%; odds ratio [OR], 1.14; P = .310), 90 days (1.1% vs 1.4%; OR, 1.23; P = .090), or 2 years (2.3% vs 2.3%; OR, 1.01; P = .931). CAN was associated with a significantly higher rate of periprostetic fracture at 30 days (0.4% vs 0.6%; OR, 1.46; P = .040) as well as revision THA at 30 days (1.0% vs 1.4%; OR, 1.43; P = .003) and 90 days (1.2% vs 1.7%; OR, 1.42; P < .002) when compared to conventional THA. The risk of deep vein thrombosis and pulmonary embolism was lower in the CAN group (p<0.05). This is a real world data report benefiting from a large database but limited by retrospective design and the authors call for additional research.³²

A 2014 meta-analysis of level 1 randomized controlled trials (RCTs) comparing TKA using CAN to conventional showed a mild improvement in alignment within 3 degrees of ideal mechanical alignment with CAN and modest functional improvement in short-term functional outcomes.³³

Another 2014 systematic review and meta-analysis evaluated 15 RCTs (n=2089) in which 1111 had CAN and 978 conventional methods. A mechanical axis of more than 30° was considered to be malalignment and an outlier in limb alignment. The evaluation reported a significant increase of 16.9 minutes in the mean operative time for CAN during TKA (p=0.46). Patients undergoing CAN had fewer outliers in mechanical axis (13.4%) compared with conventional TKA (27.4%), however the result did not achieve statistical significance (I²=0.0%; P=1.000). Slightly fewer complications were observed in patients undergoing CAN (4%) compared with conventional (6.5%). The authors recommend additional research with longer term follow up.³⁴

A systematic review and meta-analysis reported on CAN with iASSIST and conventional therapy for TKA and found no statistically significant difference. This study included 5 RCT and 3 retrospective reports (n=588) of which 275 patients were in the CAN group and 283 conventional. Five studies were rated high and 3 moderate quality evidence although this would represent an upgrading of the retrospective reports. The occurrence of malalignment of >3 degrees in the iASSIST group was 13.3%, compared with 29.04% in the conventional group. Operative time was longer in the CAN group and there was no advantage in short-term functional scores. Limitations include the inclusion of retrospective studies and therefore low-quality evidence, high heterogeneity, insufficient data in some studies and wide variables. A RCT of this same device enrolled 60 patients (30 CAN and 30 conventional) who underwent TKA. Surgical alignments measured by CT scan 6 weeks postoperatively reported statistically a significant difference in the femoral sagittal angle (89.4±2.2 in the iAssist versus 87.2±2.1 in the conventional group; p=0.003). Functional outcomes and quality of life were measured at 6 months, 1 year and 2 years postoperatively and were comparable between groups.³⁵ There were too few data on patient-oriented outcomes to draw conclusions on this device.³⁶

A prospective randomized trial compared 100 subjects undergoing conventional TKA’s to 100 undergoing CAN with a mean follow-up of 12 years using Insall Knee Score, WOMAC, Hospital for Special Surgery Knee Score, and VAS. A follow-up rate of at least 75% was achieved and they did not find a difference in TKA survival at 12 years postoperatively between the groups or revisions at 5 years. The conventional group showed a nonsignificant higher inaccuracy of neutral lower limb axis (1.8 ± 1.4 degrees) compared to CAN (1.6± 1.7 degrees , P=0.700). X-ray assessments (P=0.068), clinical examination showed no differences in evaluations (P=0.204) and all collected outcome score results were similar (P =0222). In conclusion there were no significant differences found at 12 years postoperatively between conventional and CAN groups.³⁷

A National Joint registry in New Zealand analyzed 9054 primary TKA with outcomes measured by the Oxford Knee questionnaires at 6 months and 5 years. Using multivariant analysis the authors did not find a significant difference in mean Oxford knee scores between the CAN and conventional groups at 6 months (39.0 vs 38.1, P = 0.54) or 5 years (42.2 vs 42.0, P = 0.76). There was no difference in revision rates between the groups (p=0.8).³⁸

The American College of Surgeons National Surgical Quality Improvement Program database was used to identify 103,855 patients that had TKA or THA. Analysis of this data comparing conventional vs. CAN procedures showed the CAN group experienced a minor reduction in adverse events in the first 30 days post-operatively, but also a higher number of re-operations for TKA and superficial infections for THA in the CAN group.³⁹

A retrospective cohort study included 803,732 patients undergoing THA of which 1.81% (n=14,540) had CAN utilized. The authors report CAN was associated with a lower rate of dislocation (1.00% CAN versus 1.70% conventional) and reduce rates of aseptic revision (1.91% versus 2.31%; p = 0.077). This report is limited by the retrospective design, confounding, and causality cannot be inferred necessitating further trials to validate this technology.⁴⁰

A study of 6,912 CAN THA procedures from the Australian Orthopaedic Association National Joint Replacement Registry was conducted to assess the revision rate for dislocation in THA with the use of CAN. Although there was no difference in the rate of all-cause revision between CAN and non-navigated THA, there was a lower rate of revision for dislocation in the navigation THA cohort. Authors concluded CAN was associated with a reduced rate of revision for dislocation following THA. A reduction in the rate of all-cause revision in commonly used component combinations was also reported. (Level of evidence: Therapeutic Level III).⁴¹

A retrospective report using a manufacture database to assess the risk of revision when CAN (n=871) was used compared to conventional (n=41,683) THA for osteoarthritis reported no significant difference in the 6-month Oxford Hip Score, EQ-5D, VAS scores, and patient-reported success rates. There were 943 revisions in the non-computer-guided group and 7 in the computer-guided group. The cumulative revision rate at 10 years was 3.88% (95% confidence interval [CI]: 3.59% to 4.18%) for the conventional group and 1.06% (95% CI: 0.45% to 2.76%) for the CAN group. In the analysis of the cementless-only group, the cumulative revision rate at 10 years was 3.99% (95% CI: 3.62% to 4.38%) and 1.20% (95% CI: 0.52% to 3.12%) for the 2 groups, respectively. The authors concluded that the use of CAN was associated with a lower rate of revision at mean follow-up of 5.6 years. However, this conclusion is limited due to retrospective design and causality cannot be inferred and needs to be validated in future studies. The study was funded by a device manufacturer.⁴²

A retrospective, single-center case series with 62 patients explored Intellijoint Hip (Intellijoint Surgical, Inc.) reported similar results for THA performed with CAN with Intillijoint (n= compared to conventional up to 90 days post-operatively.⁴³ Another retrospective report with 69 patients at a single-center reported excellent agreement between the CAN and conventional THA procedures.⁴⁴ An ECRI evidence analysis reports inconclusive evidence for Intellijoint Hip.⁴⁵

A systematic review compared CAN with Hip Align (OrthoAlign) to conventional techniques. The literature included was 1 RCT and 2 retrospective reports. The report concluded there was no significant difference in the target position for cup abduction between the groups (MD = −1.82, 95% CI = −4.32–0.67, [p = 0.15]). The concluded that the CAN could be slightly more precise but increased surgical time.⁴⁶ Three retrospective reports with 61-104 subjects and 1 small prospective study with 30 patients were included in an evidence analysis by ECRI which concluded very low quality evidence to support Hip Align.⁴⁷

A retrospective review of 420 patients who had primary THA with a single surgeon using fluoroscopic-assisted CAN software (n=209) were compared to those with traditional approach (n=211). The authors reported correct placement of the cup in 94% of the manual cohort and 95% of the CAN cohort. Additionally, 69% and 66 % respectively were within the acceptable range for final leg length discrepancy. This study is limited by retrospective design, single surgeon, lack of randomization or controls and use of postoperative standing radiographs for evaluating accuracy as compared to CT scan.⁴⁸ Another retrospective report found similar outcomes for acetabular cup adduction and leg length discrepancy between manual and digital systems in 433 patients.⁴⁹ These studies utilized OthoGrid Hip AI and ECRI reported on OrthoGrid Hip AI (Zimmer Biomet) image-based navigation software for THA reported too few data points with very low confidence in evidence for OthoGrid Hip AI.⁵⁰

A retrospective, multi-center, single surgeon, non-randomized study of 235 patients who underwent THA with Velys Hip Navigation technology (n=100) were compared to direct visualization (n=135). The mean difference in global offset was not statistically significant between the conventional (mean: 2.15 mm) and CAN (mean: 1.85 mm) groups (P =.898), while leg length discrepancy favored Velys (mean 1.52 mm vs. mean 2.26 mm).⁵¹ Another retrospective, single centered, single surgeon, non-randomized comparative study (n=109) compared THA with Velys Hip Navigation system to conventional THA and found no statistical difference in leg length discrepancy. The CAN group had less radiation exposure and shorter operative times in this cohort.⁵² A retrospective, single center, non-randomized study of 100 cases of THA with Velys Hip Navigation compared one surgeon using CAN with Velys to another surgeon performing conventional THA and found less difference between planned and actual limb lengthening in the CAN compared to conventional groups. These reports are limited by their retrospective design with lack of randomization or control groups, lack of generalizability due to single surgeon experience, variations in the operative technique and measurement of post operative acetabular cup placement. An ECRI evidence analysis reported very low-quality literature with too few data outcomes to draw conclusions to support Velys Hip Navigation.

The American Academy of Orthopedic Surgeons Guidelines for Management of Osteoarthritis of the Knee states the evidence does not supports using intraoperative navigation or patient-specific instrumentation in TKA because no differences in outcomes or complications have been shown compared with conventional instrumentation (Moderate recommendation based on high quality evidence). ^53,54 They add that there does not appear to be any benefit of the associated extra cost and operative time.

Robotics

Robotic assistance is intended to assist with bone resection, soft-tissue assessment and implant positioning using software defined spatial boundaries for orientation and reference information to identifiable anatomical structures for the accurate placement of knee implant components. This is supported by very low-quality evidence.⁵⁵ A systematic review of 17 studies consisting of cadaveric studies, retrospective cohorts and 2 small prospective cohorts with no RCTs reported a cutting error of less than 0.6 degrees using the ROSA platform. Four studies reported an improvement in functional scores with the ROSA assisted TKA and there was no difference in complications. The study is limited by inclusion of low-quality evidence, incomplete data, variations in validation methods, lack of external validation, and lack of assessment of rotation of the implants. The authors call for further studies to demonstrate if these findings have clinical benefit long term.⁵⁶ Additional retrospective reports have been published since the systematic review was complete, but no prospective comparative or RCTs. These retrospective reports were considered in an ECRI report on ROSA Knee System for TKA which concludes very-low quality data to compare ROSA to other surgical approaches including conventional TKA. ⁵⁵

A nationwide database study was conducted to evaluate the difference between robotic and non-robotic TKA on peri and postoperative complications and opioid consumption.⁵⁷ The authors reported lower revision rates, manipulation under anesthesia, systemic complications and opioid consumption for postoperative pain management in the robotic arm. This study is limited by retrospective design, data limited to a single robotic platform, high risk of confounding and risk of selection bias specifically in regard to opioid data, short term follow up which limits the understanding of complications beyond 90 days to 1 year, variations in patient selection with potentially higher risk patients in the non-robotic group resulting in low-quality evidence.

The US Food and Drug Administration Manufacturer and User Facility Device experience database was utilized to report adverse events related to robotic assistance in TKA and THA. There were 263 adverse events reported with the most commonly being unexpected robotic arm movement and retained registration checkpoint. There were 99 reports of surgical delay (average delay of 20 minutes), 31 cases were converted to manual surgery, 68 injuries of which six required surgical reinterventions. The authors conclude that overall robotic assisted arthroplasty is generally safe, however may result in surgical delays, there is some risk of serious complications and practices to improve safety should be considered.⁵⁸

A systematic review using PRISMA guidelines was conducted and included 10 studies which consisted of case reports, case series and 1 retrospective case-controlled study. The overall trend of the reports is the potential advantages of robotics over conventional techniques in minimizing bone loss and reducing augment utilization. The authors acknowledge technical issues that need to be optimized before robotic assistance would be considered a standard procedure and further research to determine if it improves functional outcomes and implant survivorship. The overall quality of literature available was very low quality.⁵⁹

A systematic review included 18 studies (n=2,811) and reported no significant difference between the robotic device and manual cohorts. There was no significant difference between Mako THA and manual THA patients by random-effect model (MD: 8.73, 95% CI - 4.79 to 22.25; p = 0.21).⁶⁰ The authors called for further research with higher quality and larger sample sizes to further strengthen findings.

A systematic review compared radiological outcomes for robotic assisted THA compared to manual and included 7 RCTs, 2 prospective nonrandomized and 11 retrospective studies reporting on 4,140 patients. There was no difference demonstrated for acetabular inclination or anteversion but there was a higher rate of cup orientation within the Lewinnek and Callanan safe zones, improved femoral stem alignment, and lower [GOD] and limb length discrepancy (all p-values <0.05). Most of the studies had a low risk of bias however the majority had a small sample size, wide variation in surgical approach and lack of generalizability due to variations in surgeon experience.⁶¹

A meta-analysis with 4,242 patients and 17 studies reported more acetabular components placement in safe zones in the manual group and better Harris Hip Score in the robotic group. There was no difference in [leg length discrepancy (difference -0.50, 95% CI -2.02 to 1.02; p = 0.520)] infection rates [OR 1.10, 95% CI 0.18 to 6.83; p = 0.44], dislocation rates [OR 0.66, 95% CI 0.15 to 3.02; p = 0.38], overall complication rates [OR 0.61, 95% CI 0.30 to 1.24], and survival rates [OR 0.60, 95% CI 0.21 to 1.71; p = 0.34] at short-term follow-up.⁶² The authors states that there is a lack of high quality evidence and cost analysis comparing robotic versus manual THA. A 2023 ECRI report on Mako robotic arm for THA reports very low-quality data from 6 nonrandomized comparative studies and a cost-effectiveness study in the assessment.⁶³

A systematic review of 16 studies and meta-analysis of 2,429 patients compared robotic assisted with Mako robotic arm to conventional TKA. Studies analyzed included small prospective cohorts and retrospective cohorts. Meta analysis is limited because of high variability between the studies in terms of outcome measurements used, follow up, and cohorts evaluated. Most studies had short term follow up. The author’s report improved accuracy of component positioning and early reported outcomes they acknowledge might not be clinically significant. ⁶⁴

Another systematic review compared robotic assisted with MAKO CT-based robotic-assisted system to manual TKA and found with 26 studies and follow-up ranging from 30 days to 17 months. The author’s report reduced postoperative pain and time to discharge with the robotic arm and comparable functional outcomes at 1 year. Three comparative studies reported better implant position in the robotic group. The study is limited by low quality literature.⁶⁵ An ECRI report also evaluated Mako robotic arm for knee arthroplasty and reported very low quality evidence.⁶⁶

An evidence analysis by ECRI on robotic assisted surgical platforms for THA compares safety and effectiveness of robotic assisted versus manual THA. They report based on 1 systematic review that robotic assistance improves limb alignment and implant placement over conventional THA, but another systematic review does not demonstrate robotic assistance provides a benefit over conventional for improving hip function or revision rates. The evidence is very low quality and therefore inconclusive. The report calls for large, high quality, long term randomized controlled trials or comparative studies to further delineate whether improvements in limb alignment with robotic assistance is confirmed.⁶⁷

Literature submitted during the open comment period

A systematic review/ meta-analysis of 20 studies compared the MAKO-assisted THAs to conventional THA.(Loke 2025) The review included 13 retrospective and 7 prospective studies which included 1 RCT. Primary outcomes included Harris Hip Scores (HHS), Oxford Hip Scores (OHS) and Forgotten Joint Scores (FJS) and implant position accuracy (Proportion of implants positioned within the Lewinnek and Callanan Safe Zones). Given the challenges of high heterogeneity between studies, lack of high-quality studies and exclusion of a negative RCT⁶⁸ that explores the MAKO-assisted technology this report must be interpreted with caution.

A RCT that was included in the several of the systematic reviews (cite) consisted of a RCT comparing surgical alignment in patients undergoing unicompartmental knee arthroplasty (UKA) with robotic arm-assisted surgery to conventional manual instrumentation.⁶⁸ The authors reported procedural success with both modalities and no statistical difference between the groups in any of the patient reported clinical outcomes at 5 years. They report a lower reintervention rate in the robotic arm-assisted group with 0/130 requiring further surgery compared to 6/130 (9%) in the manual group (p<0.001), however there were no alignment or component position errors in any of these six patients. The higher reintervention cannot be attributed to manual vs robotic approach as causation is not established. This paper supports there is not a difference in outcomes from robotic arm-assist surgery to conventional manual instrumentation at 5 years. A secondary analysis exploring the early clinical outcomes (up to 8 weeks) reported lower pain scores and better early function scores for the robotic arm compared to manual, but no difference was observed at one year.⁶⁹ The authors acknowledge the sample size was too small and lack long term outcomes.

Multiple retrospective reports were submitted for review. A retrospective review paper reported on 13,802 primary, unilateral, elective posterior approach THAs performed at a single institution over 4 years (1770 robotic assisted-THAs, 3155 CAN-THAs, and 8877 Manual-THAs).⁷⁰ The cohorts were balanced based on age, gender, body mass index, femoral cementation, history of spine fusion, and Charlson Comorbidity Index. The authors reported that the robotic-assisted group had OR of 0.27 [0.08,0.97], P= 0.046 compared to manual-THA of 0.84 [0.46,1.53], p=0.571 for reoperation due to dislocation, however the confidence intervals widely overlapped and the OR of 0.27 was not statistically significant. There were many variables that were not controlled that could have impacted the outcomes and causation cannot be established. This paper supports there is not a difference in short term outcomes from robotic assisted THA and manual THA.

A retrospective reported on 140 patients who underwent robotic assisted TKA and 127 with conventional TKA with a minimum of 6 weeks follow-up were evaluated for visual analogue scores (VAS), post-operative opiate usage and length of stay.⁷¹ The authors report significant difference in length of stay (1.9 vs 2.3 days), lower VAS score and less opiate use in the robotic arm. The enrollment was not truly consecutive as the allocation was impacted by the availability of robotic instrumentation introducing potential bias. A retrospective report on 492 consecutive cases with 202 undergoing robotic TKA and 290 conventional reported similar findings of shorter length of stay (2.3 vs. 2.6 days) and lower opiate use.⁷² Operative time was increased by 9.3 minutes, however given the population of a busy single surgeon this may not be generalizable. Both studies are limited by retrospective design and short-term follow-up. A retrospective report of 210 patients with CT-based TKA compared to manual TKA also reported lower mean post-operative pain scores, however, it was not designed to determine long term comparative long term outcomes.⁷³ Another retrospective report included 2247 consecutive patients from 3 surgeons who underwent robotic assisted THA compared to manual THA and reported lower dislocation rate 0.6% vs 2.5%, respectively.⁷⁴ Causation for this difference cannot be attributed to surgical approach given a multitude of uncontrolled variables which may have impacted this result.

A prospective cohort study (n=100) demonstrates a learning curve of 12 cases for operative time and surgical team confidence for robotic THA, but no learning curve for accuracy.⁷⁵

Guidelines and Consensus statements

• 2023 American College of Rheumatology and American Association of Hip and Knee Surgeons Clinical Practice Guidelines for the Optimal Timing of Elective Hip or Knee Arthroplasty for Patients With Symptomatic Moderate-to-Severe Osteoarthritis or Advanced Symptomatic Osteonecrosis With Secondary Arthritis for Whom Nonoperative Therapy Is Ineffective⁹

Recommendations based on GRADE:

1. The panel opposes a 3 month wait prior to performing TJA in patients who have failed conservative measures. Do not recommend a mandatory trial of physical therapy, NSAIDs, braces or ambulatory aids, (conditional recommendations/certainty of evidence: low-quality evidence) or intra-articular injection of glucocorticoids or viscosupplementation (conditional recommendations/certainty of evidence: very low-quality evidence).
2. The panel opposes a delay in surgical intervention in obese patients to achieve a specified BMI (conditional recommendations/certainty of evidence: very low-quality evidence).
3. The panel recommends a delay in surgical intervention in poorly controlled diabetic patients to improve glycemic control (conditional recommendations/ certainty of evidence: very low-quality evidence) and in those with nicotine dependence for nicotine reduction/cessation (conditional recommendations/ certainty of evidence: low-quality evidence).
4. The panel recommends proceeding with surgical management without delay over delaying for optimization of non-life-threatening conditions in cases of bone loss with deformity severe ligamentous instability, and neuropathic joint (conditional recommendations/ certainty of evidence: very low-quality evidence).

• Consensus statement for perioperative care in total hip replacement and total knee replacement surgery: Enhanced Recovery After Surgery (ERAS®) Society recommendations⁶⁸

Recommendations based on GRADE:

1. The following recommendations were graded as strong with high-quality supporting evidence:
   1. 4+ weeks of smoking cessation is recommended before TKA or THA
   2. Anemia should be corrected before TKA or THA
   3. Local infiltrating anesthesia is recommended for TKA but not THA
   4. Per-operative tranexamic acid to prevent post-operative bleeding
   5. Use of NSAIDs for post-operative pain if not contra-indicated
   6. opioids may be used when required for pain control
   7. early mobilization

3. The following recommendations were graded as moderate with high-quality supporting evidence:
   1. General versus central neuroaxial techniques may both be used
   2. Spinal opioids are not recommended
   3. Gabapentinoids are not recommended for post-operative pain
   4. Pre-operative antibiotic and antithrombotic prophylaxis
   5. Surgical drains, tourniquet use and urinary catheters are not recommended
4. The following recommendations were graded as strong with low quality supporting evidence:
   1. preoperative patient education is recommended
   2. alcohol cessation is recommended before TKA or THA.

• Surgical Management of Osteoarthritis of the Knee Evidence-Based Clinical Practice Guidelines from the American Association of Orthopedic Surgeons (AAOS) ^53,54

Guidelines were developed by the AAOS with a systematic review and guideline development using Evidence to Decision framework for grading of evidence. Recommendations were rated limited, moderate, or strong based on limited, moderate, strong evidence or consensus.

The following recommendations received a strong recommendation based on high quality evidence:

1. Pre-operative peripheral nerve blocks and periarticular injections reduce post-op pain
2. Tranexamic acid reduces post-op bleeding
3. There was no difference in post-op functional status based on BMI but >BMI is associated with increase infections
4. Optimization of perioperative glucose control should be attempted in diabetic and non-diabetic patients
5. Patient specific technologies (e.g., guides, cutting blocks) are not recommended
6. There is no difference in functional outcomes or complications between kinematic or mechanical alignment

The following recommendations received a moderate recommendation:

1. Drains and tourniquets should not be used (Quality of Evidence (QoE)) =high)
2. Surgical navigation does not improve outcomes or pain over conventional techniques (QoE=high)
3. Cessation of pre-operative opioids should be attempted prior to TKA (QoE= low)

The following recommendations received a limited or consensus recommendation:

1. Smoking cessation should be attempted (QoE=low)

• American Academy of Orthopedic Surgery (AAOS) Clinical Practice Guideline Summary²⁰

The following recommendations received a strong recommendation and strength of evidence rated as strong:

1. Topical NSAIDS and oral NSAIDs and acetaminophen can improve function and quality of life when not contraindicated
2. Supervised exercise or aquatic exercise
3. Patient education programs

The following are not recommended with strong recommendations and strength of evidence rated as strong:

1. Narcotics
2. Hyaluronic acid intra-articular injections
3. Lateral wedge insoles

The following recommendations received a moderate recommendation and strength of evidence rated as strong or moderate:

1. Canes and braces can be used to improve pain and function
2. Manual therapy
3. Neuromuscular training
4. Massage
5. Weight loss
6. Intra-articular corticosteroids
7. Lavage/debridement
8. Partial meniscectomy

The following recommendations received a limited recommendation and strength of evidence rated as strong, moderate, or limited:

1. Oral or dietary supplements
2. Laser
3. Acupuncture
4. Transcutaneous electrical Nerve Stimulation (TENS)
5. Percutaneous Electrical Nerve Stimulation/Pulsed Electromagnetic Field Therapy
6. Platelet-rich plasma
7. Tibial osteotomy
8. Denervation

The following recommendations received a consensus with no reliable evidence:

1. Utility of dry needling is unclear and needs additional evidence
2. Free-floating interposition devices are not recommended

Total joint arthroplasty is established surgical intervention for joint destruction with moderate to severe pain resulting and functional disability when refractory to conservative measures. Clinical evidence supports the effectiveness of both TKA and THA in appropriately selected patients. Data suggests that 20-45% of patients do not have clear indications for surgery and may be responsible for some of the failures in this population emphasizing the importance of appropriate patient selection. Additionally, outcomes are improved when modifiable risk factors are optimized prior to surgical intervention including smoking cessation, obesity, and diabetes management. Patients are best served in a multidisciplinary approach that includes postoperative rehabilitation to restore activity and function effectively post-surgery. Joint replacement surgery is typically not indicated for inflammatory arthritis which is best managed by optimizing systemic control of the inflammatory disorder, however when there is substantial joint destruction surgical intervention may be necessary.

There has been a growing trend to utilize computer aided navigation and robotics in effort to improve alignment and reduce bone loss associated with joint replacement surgery. Some literature suggests a positive trend towards improvement based on very low- and low-quality evidence. However, most of the studies, including the systematic reviews, do not demonstrate a difference between conventional and aided outcomes with long term follow-up. There are concerns about increased operative time and cost, especially when evidence to support long term outcome improvement is lacking. While societies largely do not oppose use of these devices there is no direct societal support. In the AAOS evidence based practice guidelines state surgical navigation does not improve outcomes, function or pain over conventional techniques with moderate strength of recommendation based on high quality evidence.⁵⁴ Future investigations using high quality methodology are needed to address long-term safety, patient-oriented outcomes (e.g., functional outcomes, implant longevity, revision rates, quality of life), implant longevity, and comparison of the different devices to each other. While this does not prohibit utilizing these modalities intraoperatively, they are not considered medically necessary and therefore not eligible for separate payment.

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