Elizabeth W. Paxton

Epidemiology and Natural History of Acute Patellar Dislocation

Background The goals of this study were to (1) define the epidemiology of acute patellar dislocation, (2) determine the risk of subsequent patellar instability episodes (subluxation and/or redislocation) during the study period, and (3) identify risk factors for subsequent instability episodes. Study Design Prospective cohort study. Methods The authors prospectively followed 189 patients for a period of 2 to 5 years. Historical data, injury mechanisms, and physical and radiographic measurements were recorded to identify potential risk factors for poor outcomes. Results Risk was highest among females 10 to 17 years old. Patients presenting with a prior history of instability were more likely to be female (P < .05) and were older than first-time dislocation patients (P < .05). Fewer first-time dislocators (17%) had episodes of instability during follow-up than patients with a previous history of instability (49%) (P < .01). After adjusting for demographics, patients with a prior history had 7 times higher odds of subsequent instability episodes during follow-up than first time dislocators (adjusted odds ratio = 6.6, P < .001). Conclusions Patellar dislocators who present with a history of patellofemoral instability are more likely to be female, are older, and have greater risk of subsequent patellar instability episodes than first-time patellar dislocators. Risk of recurrent patellar instability episodes in either knee is much higher in this group than in first-time dislocators.

Prospective Trial of a Treatment Algorithm for the Management of the Anterior Cruciate Ligament–Injured Knee

Background Specific guidelines for operative versus nonoperative management of anterior cruciate ligament injuries do not yet exist. Hypothesis Surgical risk factors can be used to indicate whether reconstruction or conservative management is best for an individual patient. Study Design Prospective nonrandomized controlled clinical trial; Level of evidence, 2. Methods Patients were classified as high, moderate, or low risk using preinjury sports participation and knee laxity measurements. Early anterior cruciate ligament reconstruction (within 3 months of injury) was recommended to high-risk patients and conservative care to low-risk patients. It was recommended that moderate-risk patients have either early reconstruction or conservative care, according to the day of presentation. Assessment of subjective outcomes, activity, physical measurements, and radiographs was performed at mean follow-up of 6.6 years. Results Early phase conservative management resulted in more late phase meniscus surgery than did early phase reconstruction at all risk levels (high risk, 25% vs 6.5%; moderate risk, 37% vs 7.7%, P =. 01; low risk, 16% vs 0%). Early- and late-reconstruction patients’ Tegner scores increased from presurgery to follow-up (P <. 001) but did not return to preinjury levels. Early-reconstruction patients had higher rates of degenerative change on radiographs than did nonreconstruction patients (P <. 05). Conclusions Early phase reconstruction reduced late phase knee laxity, risk of symptomatic instability, and the risk of late meniscus tear and surgery. Moderate- and high-risk patients had similar rates of late phase injury and surgery. Reconstruction did not prevent the appearance of late degenerative changes on radiographs. Relationship between bone contusion on initial magnetic resonance images and the finding of degenerative changes on follow-up radiographs were not detected. The treatment algorithm used in this study was effective in predicting risk of late phase knee surgery.

Risk factors associated with deep surgical site infections after primary total knee arthroplasty: an analysis of 56,216 knees.

BACKGROUND Deep surgical site infection following total knee arthroplasty is a devastating complication. Patient and surgical risk factors for this complication have not been thoroughly examined. The purpose of this study was to evaluate risk factors associated with deep surgical site infection following total knee arthroplasty in a large U.S. integrated health-care system. METHODS A retrospective review of a prospectively followed cohort of primary total knee arthroplasties recorded in a total joint replacement registry from 2001 to 2009 was conducted. Records were screened for deep surgical site infection with use of a validated algorithm, and the results were adjudicated by chart review. Patient factors, surgical factors, and surgeon and hospital characteristics were identified with use of the total joint replacement registry. Cox regression models were used to assess risk factors associated with deep surgical site infection. RESULTS A total of 56,216 total knee arthroplasties were identified; 63.0% were done in women, the average age of the patients was 67.4 years (standard deviation [SD] = 9.6), and the average body mass index (BMI) was 32 kg/m2 (SD = 6). The incidence of deep surgical site infection was 0.72% (404/56,216). In a fully adjusted model, patient factors associated with deep surgical site infection included a BMI of ≥35 (hazard ratio [HR] = 1.47), diabetes mellitus (HR = 1.28), male sex (HR = 1.89), an American Society of Anesthesiologists (ASA) score of ≥3 (HR = 1.65), a diagnosis of osteonecrosis (HR = 3.65), and a diagnosis of posttraumatic arthritis (HR = 3.23). Hispanic race was protective (HR = 0.69). Protective surgical factors included use of antibiotic irrigation (HR = 0.67), a bilateral procedure (HR = 0.51), and a lower annual hospital volume (HR = 0.33). Surgical risk factors included quadriceps-release exposure (HR = 4.76) and the use of antibiotic-laden cement (HR = 1.53). In a subanalysis, operative time was a risk factor, with a 9% increased risk per fifteen-minute increment. CONCLUSIONS Use of a comprehensive infection surveillance system, combined with a total joint replacement registry, identified patient and surgical factors associated with infection following total knee arthroplasty in a large sample. High-risk patients should be counseled, and modifiable clinical conditions should be optimized. Use of antibiotic irrigation should be encouraged, but antibiotic-laden cement may not be useful. LEVEL OF EVIDENCE Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

An analysis of the risk of hip dislocation with a contemporary total joint registry.

Dislocation rates after total hip arthroplasty in a community setting have not been well documented. We used a community based joint registry to evaluate hip dislocations that occurred within 1 year after total hip arthroplasty. We evaluated patient, implant, and technical factors associated with dislocation, including primary versus revision surgery, femoral head size (28 mm versus ≥ 32 mm), operative time, surgeon volume, surgical approach, age, gender, diagnosis, American Society of Anesthesiologists (ASA) classification, and body mass index (BMI). There were 1693 primary total hip arthroplasties and 277 revision procedures performed from 2001-2003. The overall dislocation rate was 1.7% for primary total hip arthroplasties and 5.1% for revision procedures. Patients with ASA scores of 3 or 4 had a 2.3-fold dislocation increase compared with patients with scores of 1 or 2. Patients with rheumatoid arthritis had an increased risk of dislocation. The dislocation rates for primary total hip arthroplasty were 2% for 28 mm heads and 0.7% for heads ≥ 32 mm. The surgeons patient volume, surgical approach, operative time, and body mass index had no effect on dislocation.Level of Evidence: Prognostic study, level III. See Guidelines for Authors for a complete description of levels of evidence.

Risk factors associated with surgical site infection in 30 491 primary total hip replacements

We examined patient and surgical factors associated with deep surgical site infection (SSI) following total hip replacement (THR) in a large integrated healthcare system. A retrospective review of a cohort of primary THRs performed between 2001 and 2009 was conducted. Patient characteristics, surgical details, surgeon and hospital volumes, and SSIs were identified using the Kaiser Permanente Total Joint Replacement Registry (TJRR). Proportional-hazard regression models were used to assess risk factors for SSI. The study cohort consisted of 30,491 THRs, of which 17,474 (57%) were performed on women. The mean age of the patients in the whole series was 65.5 years (13 to 97; SD 11.8) and the mean body mass index was 29.3 kg/m(2) (15 to 67; SD 5.9). The incidence of SSI was 0.51% (155 of 30,491). Patient factors associated with SSI included female gender, obesity, and American Society of Anesthesiologists (ASA) score ≥ 3. Age, diagnosis, diabetes and race were not associated with SSI. The only surgical factor associated with SSI was a bilateral procedure. Surgeon and hospital volumes, use of antibiotic-laden cement, fixation method, laminar flow, body exhaust suits, surgical approach and fellowship training were not associated with risk of SSI. A comprehensive infection surveillance system, combined with a TJRR, identified patient and surgical factors associated with SSI. Obesity and chronic medical conditions should be addressed prior to THR. The finding of increased SSI risk with bilateral THR requires further investigation.

Can the Need for Future Surgery for Acute Traumatic Anterior Shoulder Dislocation Be Predicted

BACKGROUND Some surgeons believe that they can identify patients who are at high risk for shoulder redislocation and that these patients are best served by immediate surgical stabilization. This natural history study was performed to examine the validity of this concept and to determine whether it is possible to predict the need for future surgery at the time of the index injury and examination. METHODS One hundred and thirty-one patients were followed for an average of four years after their first shoulder dislocation. An extensive history was recorded and a thorough physical examination was performed on each patient. Final evaluation consisted of a physical examination, radiographic evaluation, and determination of three outcome measurements. RESULTS Twenty-nine (22%) of the 131 patients requested surgery during the follow-up period. There were twenty Bankart repairs and nine rotator cuff repairs. Forty-three patients (33%) had at least one recurrent dislocation. Thirty-nine of these patients were in the group of ninety patients under the age of forty years. Thirty-seven of these thirty-nine patients either participated in contact or collision sports or used the arm at or above chest level in their occupation. Eighteen (49%) of these thirty-seven patients had surgery. Only two of the more sedentary patients had redislocation, and none had surgery. Four (10%) of the forty-one patients over the age of forty had a redislocation, but none required a Bankart repair. However, eight (20%) of the forty-one patients required a rotator cuff repair. Eighty-eight (67%) of the 131 patients never had a redislocation. Their outcome scores were high and equivalent to those of the cohort of patients who had had a successful Bankart repair of an unstable shoulder. Patients who had redislocation but chose to cope with the instability rather than have surgery had lower outcome scores. Twenty-two (51%) of the forty-three patients who had recurrent instability had only one redislocation during the entire follow-up period, whereas some patients had as many as twelve complete redislocations. CONCLUSIONS Younger patients involved in contact or collision sports or who require overhead occupational use of the arm are more likely to have a redislocation of the shoulder than are their less active peers or older persons. However, even in the highest-risk groups, only approximately half of patients with shoulder redislocation requested surgery within the follow-up period. Early surgery based on the presumption of future dislocations, unhappiness, and disability cannot be justified.

The Reliability and Validity of Knee-Specific and General Health Instruments in Assessing Acute Patellar Dislocation Outcomes

Background The most reliable and valid instruments for assessing patient outcome after patellar dislocation have not been identified. Hypothesis Knee-specific and general health instruments will differ in validity and reliability for patients with patellar dislocation. Study Design Prospective cohort study. Methods Subjects consisted of 153 patients with acute patellar dislocation (110 with first-time dislocations and 43 with a history of patellofemoral subluxation or dislocation). We administered the modified International Knee Documentation Committee form, Kujala, Fulkerson, Lysholm, Tegner, Short Form 36, and Musculoskeletal Function Assessment instruments on two separate occasions (test-retest reliability). Validity was assessed by comparing scores of the two groups and by comparing scores of patients with and without recurrent subluxations/dislocations during follow-up. Results The knee-specific instruments yielded the highest test-retest reliability. The knee-specific and general health instruments identified higher disability levels in the patients with a history of patellofemoral problems than in those with first-time dislocations. The general health instruments identified higher disability levels in patients with patellar dislocation than published norms. The Fulkerson and Lysholm scales were the only instruments to differentiate between patients with and without recurrent subluxations/dislocations. Conclusions Knee-specific scales yielded higher reliability coefficients and stronger validity than did general health instruments. Knee-specific, general health, and activity level instruments are complementary and in combination provide a more complete assessment for patients with patellar dislocation.

The International Consortium of Orthopaedic Registries: Overview and Summary

FDA Post-Market Efforts and Interest in Orthopaedics The United States Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH) monitors both mandatory and voluntary post-market reporting to identify adverse events and problems associated with medical devices. Although the manufacturers of medical devices are required to report deaths, injuries, and malfunctions directly to the FDA, the device users are required to report these events to the manufacturer and are required to report only deaths to the FDA. Voluntary reporting systems such as the MedWatch program, the MAUDE (Manufacturer and User Facility Device Experience) database, and the MedSun (Medical Product Safety Network) enhanced surveillance network provide nationwide medical device surveillance in the U.S. However, these reporting systems have important weaknesses, such as incomplete, inaccurate, or nonvalidated data, reporting biases related to event severity, concerns that reporting may result in adverse publicity or litigation, and general underreporting of events. Most importantly, denominator data are missing, which makes evaluation of the incidence or prevalence of a safety-related event impossible. The FDA’s interest in orthopaedic device safety and in the development of infrastructure for enhanced safety monitoring is natural and timely; the lack of such safety evidence is particularly troubling for the most commonly used implants. Over 700,000 joint replacements involving implantable devices are conducted annually in the U.S. alone, and the annual volume is projected to increase twofold for hip joint replacements and sevenfold for knee joint replacements, to a total of more than 3 million annually, in just the next twenty years. Moreover, these surgical procedures are expected to become more expensive, with costs tripling in just the next five years. Despite remarkable advancements in orthopaedics, including new devices and improved surgical techniques, the value of many therapeutic devices has not been established in clinical trials or in real-world settings. Several factors contribute to this shortcoming: (1) rapidly changing device technology coupled with an enormous number of devices on the market; (2) the need for large numbers of patients and long-term follow-up to adequately evaluate the primary safety end point, which is longterm device failure or need for revision; and (3) the need for prospective data collection, planning, and substantial funding to evaluate short and long-term patient-reported outcomes, which are the primary effectiveness end points. The poor state of research and the resulting inability to learn about a device’s benefits, its potential harms, and the balance between them hinder decision-making by the FDA and other stakeholders such as the Centers for Medicare & Medicaid Services (CMS) and commercial insurers.

A Prospective Study of 80,000 Total Joint and 5000 Anterior Cruciate Ligament Reconstruction Procedures in a Community-Based Registry in the United States

Health-care costs in the United States have increased substantially over time. From 1980 to 2007, the percentage of gross national product spent on health care has increased from 8.8% to 16%1. Total joint replacement is one of the most costly diagnosis-related groups, with >600,000 procedures performed each year in the United States2,3. The demand for total joint replacement is expected to increase in the United States as a result of advances in medical technology, an increased prevalence of obesity, and an increasing aging population2,4. By 2030, annual volumes are projected to increase by 673% for primary total knee arthroplasty and by 174% for primary total hip arthroplasty4. The demand for revision total knee and total hip arthroplasty is also projected to increase by 601% and 137%, respectively. Total knee and total hip arthroplasty costs are also expected to increase dramatically, with annual hospital charges estimated to reach

Knee replacement: epidemiology, outcomes, and trends in Southern California 17,080 replacements from 1995 through 2004

40.8 billion for primary total knee arthroplasty and