Ten-Year Trends and Independent Risk Factors for Unplanned Readmission Following Elective Total Joint Arthroplasty at a Large Urban Academic Hospital.

BACKGROUND: Total joint arthroplasty procedures continue to provide consistent, long-term success and high patient satisfaction scores. However, early unplanned readmission to the hospital imparts significant financial risks to individual institutions as we shift away from the traditional fee-for-service payment model. METHODS: Using a combination of our hospital's administrative database and retrospective chart reviews, we report the 30-day and 90-day readmission rates and all causes of readmission following all unilateral, primary elective total hip and knee arthroplasty procedures at a large, urban, academic hospital from 2004 to 2013. RESULTS: In total, 1165 primary total hip (511) and knee (654) arthroplasty procedures were identified, and the 30-day and 90-day unplanned readmission rates were 4.6% and 7.3%, respectively. A multivariate regression model controlled for a variety of potential clinical and surgical confounders. Increasing body mass index levels, an American Society of Anesthesiologists score of ≥3, and discharge to an inpatient rehab facility each independently correlated with risk of both 30-day and 90-day unplanned readmission to our institution. Additionally, use of general anesthesia during the procedure independently correlated with risk of readmission at 30 days only, while congestive heart failure independently correlated with risk of 90-day unplanned readmission. Readmissions related directly to the surgical site accounted for 47% of the cases, and collectively totaled more than any single medical or clinical complication leading to unplanned readmission within the 90-day period. CONCLUSION: Increasing body mass index values, general anesthesia, an American Society of Anesthesiologists score of ≥3, and discharge to an inpatient rehab facility each were independent risk factors for early unplanned readmission.

Risk and Cost of 90-Day Complications in Morbidly and Superobese Patients After Total Knee Arthroplasty.

BACKGROUND: This study investigated the risk and cost of postoperative complications associated with morbid and super obesity after total knee arthroplasty (TKA). METHODS: A retrospective cohort study was conducted of patients who underwent TKA using Medicare hospital claims data. The International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code V85.4x was used to identify morbidly obese patients (body mass index [BMI] ≥40 kg/m(2)) and superobese patients (BMI ≥50 kg/m(2)) in 2011-2013. Patients without any BMI-related diagnosis codes were used as controls. Twelve complications occurred in the 90-day period after TKA were analyzed using multivariate Cox models, adjusting for patient demographic, morbidity, and institutional factors. In addition, hospital charges and payments were compared from primary surgery through subsequent 90 days. RESULTS: Morbidly obese patients showed a significantly elevated risk in most complications examined, with a 2-fold or higher risk in dislocation and wound dehiscence. In addition, death, periprosthetic joint infection, acute renal failure, and knee revision had significant hazard ratios between 1.5 and 2.0. However, risk of deep vein thrombosis and acute myocardial infarction did not increase for the morbidly obese patients. Superobese patients had significant increase in risk of infection, wound dehiscence, acute renal failures, revisions, death, and readmission compared with patients with BMI 40-49 kg/m(2). Significant dose-response trend was found between the level of BMI and risk for death, dislocation, implant failure, infection, readmission, revision, wound dehiscence, and acute renal failure. Controlling for patient and institutional factors, each TKA had an average total hospital charges of $75,884 among superobese patients, compared to $65,118 for the control group, a difference of $10,767. Medicare payment for the superobese patients was also higher, but only by $2703. CONCLUSION: Morbidly obese patients pose a significantly higher risk profile than normal-weight patients in a broad range of complications after TKA. Superobese patients add another layer of risk compared with less obese patients and are considerably more expensive to treat by health care systems. Technical difficulties and the high demand on resources present a severe challenge for providing treatment for such patients.

The Validity of Administrative BMI Data in Total Joint Arthroplasty.

Identifying BMI via administrative data is a useful way to evaluate outcomes in total joint arthroplasty (TJA) for varying degrees of obesity. The purpose of this study was to evaluate the concordance between BMI coding in administrative claims data and actual clinical BMI measurements in the medical record for patients undergoing TJA. Clinical BMI value was shown to be a significant determinant of whether ICD-9 codes were used to report the patient's obesity status (P<0.01). Although a higher clinical BMI strongly increased the likelihood of having either of the ICD-9 diagnosis codes used to identify obesity status, only the accuracy of the V85 code increased with increasing levels of BMI.

Prophylaxis for thromboembolic disease and evaluation for thrombophilia.

Patients treated with total hip or knee arthroplasty are at risk for venous thromboembolic disease. Laboratory evaluation of thrombophilia can help to better identify patients at higher risk for venous thromboembolic disease, and newer methods that test for genetic factors continue to evolve; however, more research is needed to justify routine testing for thrombophilia. Research studies have yielded differing results in determining the most appropriate prophylactic regimen. Both pharmaceutical and mechanical treatments are commonly used for prophylaxis. New pharmacologic prophylaxes include the Xa inhibitor rivaroxaban and the thrombin inhibitor dabigatran etexilate. The newest mechanical device used to prevent venous thromboembolism is a miniature, mobile, battery-operated pneumatic system called Continuous Enhanced Circulation Therapy. The American College of Chest Physicians guidelines and the American Academy of Orthopaedic Surgeons clinical guideline were reviewed to directly compare specific agents and balance the risks of venous thromboembolism. Future studies for venous thromboembolic prophylaxis will continue to evaluate new oral agents, improved pneumatic compression devices, and improved methods to decrease bleeding in the immediate postoperative period.

The relationship between knee arthroscopy and arthroplasty in patients under 65 years of age.

A private payer database was used to examine the incidence and rates of knee arthroscopy in patients less than 65 years of age and the subsequent risk of knee arthroplasty. Time to event analysis was performed using the Kaplan-Meier method; also, Cox regression analysis was used to evaluate the relative risk of subsequent knee arthroplasty for arthroscopic patients. Overall, 247,034 knee arthroscopies, done for injury or arthropathy, were identified between 2004 and 2009. Within 1-year of arthroscopy, 2.2% of arthropathy patients and 0.9% of injury patients underwent a knee arthroplasty. These increased to 5.2% and 2.4% at 5-years, respectively. The risk of arthroplasty following arthroscopy increased significantly with age. Further study is warranted to examine the benefit of arthroscopy in younger patients with OA.

Percutaneous column fixation and total hip arthroplasty for the treatment of acute acetabular fracture in the elderly.

We used our database of primary total hip arthroplasties to identify those patients who had acetabular fractures fixed with percutaneous screws under the same anesthesia as for the arthroplasty procedure. There were 19 patients with the average follow-up of 22 months. Fourteen patients sustained the fracture secondary to a low-energy trauma, while the remaining patients were involved in a high-energy trauma accident. The mean survival time was calculated to be 2.5 ± 0.6 years for the low-energy group and 4 ± 1.4 years for the high-energy group. We believe that this unique treatment of acetabular fractures has a role in carefully selected patients and provides the necessary reduction and immediate stability of the fracture needed to ensure adequate fit for the acetabular cup in the subsequent THA.

Decreased ratios of lateral to medial patellofemoral forces and pressures after lateral retinacular release and gender knees in total knee arthroplasty.

PURPOSE: To demonstrate that lateral to medial patellofemoral force and pressure ratios could be a surrogate marker of retinacular tension and patellar tracking. METHODS: The patellofemoral forces of six knees from three fresh-frozen half-body female cadavers were evaluated with a capacitive sensor under simulated operative conditions in six staged clinical scenarios: native knees, knee arthroplasty without patellar resurfacing, resurfaced knee and patella, resurfaced knee and patella with lateral release, gender-specific knee arthroplasty with patella resurfacing, and gender-specific knee arthroplasty with lateral release. Maximum force and peak pressure were simultaneously recorded during three to four ranges of motion. Average values were compared between lateral and medial patellofemoral compartments as an objective measure of patellar tracking for the different settings. RESULTS: Significant differences in lateral and medial force and pressure differentials were seen in most scenarios despite clinically normal patellar tracking. Lateral to medial ratios of maximum force and peak pressure significantly increased after TKA (2.9, 2.1) and after patella resurfacing (2.8, 2.6) compared to the native knee (1.6, 1.8). Addition of a lateral release in resurfaced knees decreased the ratio of lateral to medial patellofemoral forces and pressures as did gender knee arthroplasty (1.5 and 1.1, 2 and 1.3, respectively). Pressure and force values most closely resembled the native knee in the resurfaced knee/resurfaced patella with lateral release and in the gender knee arthroplasty scenarios. CONCLUSIONS: Use of lateral to medial patellofemoral force ratios as a surrogate objective marker for patellar tracking was validated in this study by decreasing ratios observed after lateral release in TKA and with gender-specific implants.

Does lateral release change patellofemoral forces and pressures?: a pilot study.

BACKGROUND: One complication of TKA is postoperative anterior knee pain. Balancing retinacular tissue tension to improve patellar tracking is essential in preventing pain. Lateral release might help balance tension although the quantitative changes in patellofemoral force and pressure differentials after lateral release are unknown. QUESTIONS/PURPOSES: We asked if there are differences in patellofemoral forces and pressures for knees resurfaced with standard and gender-specific components and whether lateral release changes these differentials. METHODS: We studied six fresh-frozen cadaver knees with native knees and knees that had TKAs with patellofemoral resurfacing using traditional and gender-specific components. The knees were taken through passive ROM, and the means for medial and lateral peak pressure and maximum force were calculated before and after a lateral release was performed. RESULTS: In traditional resurfaced knees, lateral peak pressure was greater than medial peak pressure by 727.6 ± 550.0 kPa and lateral maximum force was greater than medial maximum force by 29.6 ± 15.9 N. Lateral release decreased the pressure (71.4 ± 826.0 kPa) and force (10.0 ± 32.1 N) differentials in the traditional but not in the gender-specific design. In gender-specific resurfaced knees, lateral peak pressure was greater than medial peak pressure by 158.7 ± 360.0 kPa and lateral maximum force was greater than medial maximum force by 15.5 ± 10.4 N. Lateral release increased the pressure (285.7 ± 565.0 kPa) and force (16.8 ± 10.8 N) differentials. CONCLUSIONS: Our preliminary data suggest lateral release is more effective in reducing peak pressure and maximum force differentials in knees resurfaced with traditional standard components than with gender-specific components. CLINICAL RELEVANCE: The lateral release technique might help with tissue balancing when using standard components in TKA.

Revision total hip arthroplasty without bone graft of high-grade acetabular defects.

Mixed results have been reported with bulk and cancellous bone graft to fill defects during acetabular revision arthroplasty. Jumbo cups have been used to maximize host bone contact, and if adequate initial stability can be achieved, this approach may provide a superior long-term outcome. We retrospectively reviewed a consecutive series of 107 acetabular revisions performed using jumbo cups without bone graft. Bone defects were assessed using a validated radiographic classification system that yielded 64 hips with significant bone defects for inclusion. Mean change in American Academy of Orthopaedic Surgeons lower extremity core and pain scores and in Short Form-12 scores showed increases of 22.01, 37.52, and 17.08 points, respectively. Postoperative radiographs consistently demonstrated host bone ingrowth into the jumbo acetabular shells, except for 3 failures. Careful incremental reaming up to a size that optimizes host bone support and contact may eliminate the need for bone graft in most acetabular revision arthroplasties.

Surgical treatment options in patients with impaired bone quality.

BACKGROUND: Bone quality should play an important role in decision-making for orthopaedic treatment options, implant selection, and affect ultimate surgical outcomes. The development of decision-making tools, currently typified by clinical guidelines, is highly dependent on the precise definition of the term(s) and the appropriate design of basic and clinical studies. This review was performed to determine the extent to which the issue of bone quality has been subjected to this type of process. QUESTIONS/PURPOSES: We address the following issues: (1) current methods of clinically assessing bone quality; (2) emerging technologies; (3) how bone quality connects with surgical decision-making and the ultimate surgical outcome; and (4) gaps in knowledge that need to be closed to better characterize bone quality for more relevance to clinical decision-making. METHODS: PubMed was used to identify selected papers relevant to our discussion. Additional sources were found using the references cited by identified papers. RESULTS: Bone mineral density remains the most commonly validated clinical reference; however, it has had limited specificity for surgical decision-making. Other structural and geometric measures have not yet received enough study to provide definitive clinical applicability. A major gap remains between the basic research agenda for understanding bone quality and the transfer of these concepts to evidence-based practice. CONCLUSIONS: Basic bone quality needs better definition through the systematic study of emerging technologies that offer a more precise clinical characterization of bone. Collaboration between basic scientists and clinicians needs to improve to facilitate the development of key questions for sound clinical studies.

Measuring patellofemoral forces and pressures in a simulated operating room environment.

The purpose of this study was to use a validated capacitive pressure (Novel Electronics, Inc, St Paul, Minn) in the measurement and distribution of patellofemoral forces and pressures during simulated operative procedures. Six fresh frozen cadaver knees were evaluated through a range of motion and observations recorded in native knees (NKNP) with sequential resurfacing of tibiofemoral (RKNP) and patellofemoral (RKRP) articulations with standard and gender (GKRP) components. Significant lateral-medial maximum force differentials were observed for all conditions. Significant lateral-medial peak pressure differentials were observed in RKNP and RKRP. A significant decrease in lateral maximum force from RKRP to GKRP (P = .01) was observed. Significant increases in lateral peak were seen from NKNP to RKNP (P = .04) and RKNP to RKRP (P = .047), whereas a significant decrease was seen from RKRP to GKRP (P < .01). Achieving a quantitative intraoperative assessment of patellar tracking and soft tissue balancing may offer benefits in terms of intraoperative decision making. This is the first reported study to simulate quantitative, intraoperative assessments of patellofemoral pressure and force.

Temporal relationship between knee arthroscopy and arthroplasty: a quality measure for joint care?

This study examined the incidence and rates of knee arthroscopy in patients older than 65 years and the risk of subsequent knee arthroplasty. Medicare claims data (1997-2006, 5% sample) were used to identify 78,137 knee arthroscopy patients. Performance of arthroscopy increased 56.1%. Prevalence increased 44.6% from 362.2 to 523.7 per 100,000 Medicare patients. The prevalence was greater for women and white patients. Prevalence of knee arthroscopy was greater in the South. Within 1 year after arthroscopy, 10.2% of arthropathy patients and 8.5% of injury patients underwent knee arthroplasty. A progressive increase was seen in the rates of use of knee arthroscopy in elderly Medicare patients for a 10-year period. A 10.2% failure rate 1 year after knee arthroscopy may be a reasonable benchmark against which performance of knee arthroscopy in patients older than 65 years can be measured.

Challenges with health-related quality of life assessment in arthroplasty patients: problems and solutions.

Assessment of health-related quality of life (HRQOL) using patient-reported outcomes in arthroplasty has become popular because it provides a unique perspective on successful elective procedures. However, challenges exist in the assessment of HRQOL in clinical practice and in clinical research. Patient compliance with multiple and sometimes lengthy HRQOL assessments administered at multiple follow-up visits is problematic. Many well-validated HRQOL instruments are available, and progress has been made in defining the minimal clinically important difference in hip and knee arthroplasty that denotes the minimal change perceived to be important by patients. Challenges in understanding the literature are attributable to the use of various HRQOL scales, with different scoring ranges and scoring algorithms, different interpretations of highest score, and differences in the presentation of raw versus transformed scores.

Grading acetabular defects: the need for a universal and valid system.

Preoperative classification of acetabular bone loss in revision total hip arthroplasty has been problematic. An evidence-based approach involves having a validated and widely accepted system of classification. A prerequisite would be a system that describes each defect in terms that are mutually exclusive, hierarchical, surgically relevant, and corresponding to experienced clinicians' preoperative estimates of surgical complexity. Of the 6 systems reviewed, only 1 demonstrated the reliability and validity required for a standardized grading system. Although high-grade defects were seen in only 17% of the 1094 hips, the failure rate associated with them was 30%. A larger population of high grade defects is necessary to determine which treatment alternatives are successful.

Prevention of symptomatic pulmonary embolism in patients undergoing total hip or knee arthroplasty.

This clinical practice guideline is based on a systematic review of published studies on the management of adult patients undergoing total hip replacement (THR) or total knee replacement (TKR) aimed specifically at preventing symptomatic pulmonary embolism (PE). The guideline emphasizes the need to assess the patient's risk for both PE and postoperative bleeding. Mechanical prophylaxis and early mobilization are recommended for all patients. Chemoprophylactic agents were evaluated using a systematic literature review. Forty-two studies met eligibility criteria, of which 23 included patients who had TKR and 25 included patients who had THR. The following statements summarize the recommendations for chemoprophylaxis: Patients at standard risk of both PE and major bleeding should be considered for aspirin, low-molecular-weight heparin (LMWH), synthetic pentasaccharides, or warfarin with an international normalized ratio (INR) goal of < or =2.0. Patients at elevated (above standard) risk of PE and at standard risk of major bleeding should be considered for LMWH, synthetic pentasaccharides, or warfarin with an INR goal of < or =2.0. Patients at standard risk of PE and at elevated (above standard) risk of major bleeding should be considered for aspirin, warfarin with an INR goal of < or =2.0, or none. Patients at elevated (above standard) risk of both PE and major bleeding should be considered for aspirin, warfarin with an INR goal of < or =2.0, or none.

Clinical anatomy of the quadriceps femoris and extensor apparatus of the knee.

Most descriptions of the extensor mechanism of the knee do not take into account its complexity and variability. The quadriceps femoris insertion into the patella is said to be through a common tendon with a three-layered arrangement: rectus femoris (RF) most superficially, vastus medialis (VM) and lateralis (VL) in the intermediate layer, and vastus intermedius (VI) most deeply. We dissected 20 limbs from 17 cadavers to provide a more detailed description of the anterior components of the knee: the tendon, the patellar retinacula, and the patellofemoral ligaments. Only three of the 20 specimens exhibited the typically described quadriceps pattern. The remainder had bilaminar and even more complex trilaminar and tetralaminar fiber arrangements. We found an oblique head of the vastus lateralis (VLO), separated from the longitudinal head by a layer of fat or fascia, in 60% of the specimens. However, we found no distinct oblique head of the vastus medialis (VMO) in any specimen. The medial patellofemoral ligament (MPFL) was more common than the lateral (LPFL), supporting its suggested role as the principal passive medial stabilizer of the patella. Because the quadriceps muscle group plays a direct role in patellofemoral joint function, investigation into the clinical applications of its highly variable anatomy may be worthwhile with respect to joint dysfunction and failures of TKAs.

Treatment of symptomatic greater trochanteric fracture after total hip arthroplasty.

Isolated greater trochanter fractures after total hip arthroplasty are associated with major comorbidities such as debilitating weakness, pain, and dislocation. No definitive standard of care has been established for these fracture. However, it is well known that reestablishing osseous union in these patients is strongly associated with return of functional status. We report a case of an elderly patient with multiple hip revision surgeries now presenting with unilateral greater trochanter fracture. Treatment incorporated the use of a trochanteric claw plate, cerclage wiring, and adjuvant demineralized bone matrix allograft to achieve successful osseous union. This is the first reported use of adjuvant demineralized bone matrix for fixing these fractures.

Knee arthrodesis.

Arthrodesis is one of the last options available to obtain a stable, painless knee in a patient with a damaged knee joint that is not amenable to reconstructive measures. Common indications for knee arthrodesis include failed total knee arthroplasty, periarticular tumor, posttraumatic arthritis, and chronic sepsis. The primary contraindications to knee fusion are bilateral involvement or an ipsilateral hip arthrodesis. A variety of techniques has been described, including external fixation, internal fixation by compression plates, intramedullary fixation through the knee with a modular nail, and antegrade nailing through the piriformis fossa. Allograft or autograft may be necessary to restore lost bone stock or to augment fusion. For the carefully selected patient with realistic expectations, knee arthrodesis may relieve pain and obviate the need for additional surgery or extensive postoperative rehabilitation.

American Academy of Orthopaedic Surgeons lower limb outcomes assessment instruments. Reliability, validity, and sensitivity to change.

BACKGROUND: The American Academy of Orthopaedic Surgeons (AAOS) has developed an array of outcomes assessment instruments designed for the efficient collection of outcomes data from patients of all ages with musculoskeletal conditions in all body regions. The Lower Limb Instruments were developed through a process of literature review, consensus-building, and field-testing. METHODS: The instruments were distributed to a total of 290 subjects in twenty orthopaedic practices throughout the United States and Canada. Of the 290 patients, seventy each had a diagnosis in the categories of foot and ankle, sports/knee, and hip and knee and forty each had a diagnosis in the categories of trauma and rehabilitation. Retests to be taken twenty-four hours after the first test were distributed to subsamples of patients for each instrument. Seventy-one one-year follow-up questionnaires (twenty-five Sports/Knee, twenty-five Foot and Ankle, sixteen Hip and Knee, and five Lower Limb Core instruments) were returned. RESULTS: The Lower Limb Core Scale and the Hip and Knee Core Scale, each consisting of seven items addressing pain, stiffness and swelling, and function, performed at an acceptable level. Additional Sports/Knee and Foot and Ankle Modules proved to have internal and retest reliability of 0.80 or better, comparable with the values for well-established measures such as the Short Form-36 (SF-36). All of the new scales were moderately to strongly correlated with other measures of pain and function, such as physician ratings, the SF-36, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Seventy-one patients provided follow-up information for the analysis of sensitivity to change. The Lower Limb Core was found to contribute independently to the prediction of the transition score based on the patient and physician assessments of change. CONCLUSIONS: The AAOS Lower Limb Instruments for outcomes assessment are highly reliable and are correlated with other measures for similar constructs. They are also sensitive to change in patient status. The Lower Limb Core Scale may be used with attribution of pain either to the lower limb or to a specific joint or side without sacrificing reliability. Combined with the SF-36, the AAOS outcomes assessment instruments comprehensively and efficiently measure outcomes in orthopaedic patients with lower-limb conditions.