Matthew S. Austin

Irrigation and debridement in the management of prosthetic joint infection: traditional indications revisited.

Irrigation and debridement (I and D) is a procedure commonly used for the treatment of acute periprosthetic infection. This study retrospectively reviewed clinical records of patients with periprosthetic infection of the hip or knee who underwent I and D with retention of their prostheses between 1997 and 2005 at a single institution. One hundred four patients (44 males and 60 females) were identified. Mean age at time of initial debridement was 65 years. Average follow-up was 5.7 years. Treatment failure was defined as the need for resection arthroplasty or recurrent microbiologically proven infection. According to these criteria, I and D was successful in 46 patients (44%). Patients with staphylococcal infection, elevated American Society of Anesthesiologists score, and purulence around the prosthesis were more likely to fail. The high failure rate of this procedure implies that it should be preferably limited to select healthy patients with low virulence organisms and equivocal intraoperative findings.

Custom-Fit Total Knee Arthroplasty (OtisKnee) Results in Malalignment

We report on 4 patients who underwent total knee arthroplasty with OtisKnee system (OtisMed, Hayward, Calif). An image-free computer navigation system was used to evaluate the deformities and the recommended cuts. The recommended custom cuts were as follows: valgus/varus cuts on the femur (5.5 degrees valgus to 0.5 degrees varus) in reference to the mechanical axis, flexion cuts on the femur (4 degrees -9 degrees of flexion); femoral rotation was within 1 degrees of the epicondylar axis; valgus/varus cut on the tibia (3 degrees of valgus to 7.5 degrees of varus); tibial slope (5.5 degrees of anterior slope to 0.5 degrees of posterior slope). The custom OtisKnee system guides recommended alignment of the components that was more than 3 degrees off of mechanical axis. The potential for malalignment with this system places implants at high risk of early failure.

Preventing Infection in Total Joint Arthroplasty

Recent projections have forecast that by the year 2030 the number of primary total knee arthroplasty procedures will increase to 3.48 million, an increase of 673% compared with 2005, and the number of primary total hip arthroplasties will increase by 174% to 572,000, with the expectant result being that over 4 million primary total joint arthroplasties will be performed in the United Stated annually1. Similarly, the number of arthroplasty revision procedures is projected to increase correspondingly. Periprosthetic joint infection is a devastating complication and is one of the leading causes of morbidity following total joint arthroplasty, with a mortality rate ranging between 2.7% and 18%2-10. The average rate of periprosthetic joint infection within two years after primary hip or knee replacement is between 0.25% and 2.0%3,7,11-15. Hence, a tremendous psychological and financial burden is placed on the patient and the health-care system, with the cost of treatment of each episode of periprosthetic joint infection estimated to be three to four times the cost of a primary total joint arthroplasty7,8,10. As the “at-risk” population pool is predicted to expand dramatically, so too will the burden of infection as recent epidemiologic studies have suggested that both the incidence and the prevalence of periprosthetic joint infection may be increasing over time in the United States1,7,16. Kurtz et al., using a Nationwide Inpatient Sample database, showed that, between 1990 and 2004, a nearly twofold increase was observed in the incidence of infection for both hip and knee arthroplasty in the United States16. The reason for this increase is multifactorial and includes both host and agent-related factors. Improvement in the medical care of patients, especially those who …

Prosthetic joint infection caused by gram-negative organisms.

Traditionally, periprosthetic joint infections (PJIs) due to gram-negative organisms are considered more difficult to manage; however, little literature exists with regard to outcome of PJI caused by gram-negative organisms. We identified 277 patients with 282 culture-positive PJI receiving surgical treatment. Thirty-one joints were treated for gram-negative PJI. The gram-negative group was then compared with the gram-positive and polymicrobial PJI. A single debridement and retention of prosthesis were successful in 70% (7/10) of isolated gram negative compared with 33.3% (13/39) of methicillin-sensitive gram positive, 48.9% (23/47) of methicillin-resistant gram positive, and 57.1% (4/7) of polymicrobial. Of those patients undergoing a planned 2-stage exchange, a successful reimplantation was performed in 52% (12/23) of gram-negative, 51% (52/103) of methicillin-resistant gram-positive, 69% (65/94) of methicillin-sensitive gram-positive, and 0% (0/8) of polymicrobial PJI cases. These results indicate that PJI due to gram-negative pathogens, although less common, is difficult to treat and is associated with limited success.

Image-guided spine surgery: a cadaver study comparing conventional open laminoforaminotomy and two image-guided techniques for pedicle screw placement in posterolateral fusion and nonfusion models.

Study Design. A randomized comparison of conventional and image-guided technology techniques for pedicle screw placement was performed. Objective. To evaluate the accuracy of thoracolumbosacral pedicle screw placement in simulated posterior fusion and nonfusion models via conventional and image-guided surgical techniques. Summary of Background Data. Computer-assisted image-guided technology has been promoted as a means for theoretically improving the accuracy of spinal instrumentation placement, especially when visual landmarks are obscured. Methods. Seven embalmed cadaveric spines were cleared of all posterior soft tissue and mounted. The posterior elements of four spines were obscured so as to simulate a fusion mass using a synthetic bone cement. Three nonobscured spines also were instrumented. Pedicle screws were placed from T6 to S1 in two obscured specimens (24 screws) using a computer-assisted image-guided system, in one obscured specimen from T6 to S1 (12 screws) using a fluoroscopically assisted system, and in one obscured specimen from T6 to S1 (14 screws) using a conventional open laminoforaminotomy technique. In addition, pedicle screws were placed from T6 to S1 using a fluoroscopically assisted technique in two unobscured specimens (36 screws), and from from T6 to S1 (14 screws) via a laminoforaminotomy technique in one unobscured specimen. Pedicle violation was assessed by computed tomography scanning and direct visual inspection. The degree of screw misplacement noted visually was quantified with an electronic caliper. Results. Pedicle screws placed via open laminoforaminotomy resulted in a pedicle cortex breach rate of 21.43% in fused specimens and 14.29% in nonfused specimens. Screws placed in the nonfused model (two cadavers) via fluoroscopically assisted methods had pedicle cortical breaches, respectively, in 6.25% and 10% of the specimens, whereas the same method was noted to have a 8.33% violation rate in the fusion model. Finally, computed tomography–based image-guided placement through a simulated fusion mass resulted in no pedicle wall violations. Conclusions. Accuracy of pedicle screw placement in the thoracolumbosacral spine is improved with the use of image-guided methods, particularly guidance by computed tomography. This is especially relevant clinically when the anatomy is obscured or altered as a result of inflammatory spondyloarthropathy (e.g., ankylosing spondylitis in which spontaneous fusions obscure surgical landmarks for pedicle access), or when used postsurgically in the setting of a posterolateral fusion.

Operating room traffic is a major concern during total joint arthroplasty.

BackgroundPeriprosthetic joint infection (PJI) is a challenging complication associated with total joint arthroplasty (TJA). Traffic in the operating room (OR) increases bacterial counts in the OR, and may lead to increased rates of infection.Question/purposesOur purposes were to (1) define the incidence of door opening during primary and revision TJA, providing a comparison between the two types of procedures, and (2) identify the causes of door opening in order to develop a strategy to reduce traffic in the operating room.MethodsAn observer collected data during 80 primary and 36 revision TJAs. Surgeries were performed under vertical, laminar flow. Operating room personnel were unaware of the observer, thus removing bias from traffic. The observer documented the number, reason, and personnel involved in the event of a door opening from time of tray opening to closure of the surgical site.ResultsThe average operating time for primary and revision procedures was 92 and 161 minutes, respectively. Average door openings were 60 in primary cases and 135 in revisions, yielding per minute rates of 0.65 and 0.84, respectively. The circulating nurse and surgical implant representatives constituted the majority of OR traffic.ConclusionsTraffic in the OR is a major concern during TJA. Revision cases demonstrated a particularly high rate of traffic. Implementation of strategies, such as storage of instruments and components in the operating room and education of OR personnel, is required to reduce door openings in the OR.

A simple, cost-effective screening protocol to rule out periprosthetic infection.

The differential diagnosis of pain after total knee arthroplasty includes infection. Effective screening tools should have high sensitivity and are cost-effective. We evaluated 296 patients who underwent total knee revision at our institution. One hundred sixteen patients (39%) were classified as infected and 180 patients (61%) were considered noninfected. The mean erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) of the infected patients were 85 mm/h and 110 mg/L, respectively. The mean ESR and CRP of the noninfected patients were 22 mm/h and 7 mg/L, respectively. Five patients (4%) in the infected group had both normal ESR and CRP. Infection was suspected in all 5 patients, and an organism was cultured in 4 of the 5 cases. Erythrocyte sedimentation rate and CRP, when used in combination, serve as a useful screening tool in patients with a painful total knee arthroplasty.

Swab cultures are not as effective as tissue cultures for diagnosis of periprosthetic joint infection.

BackgroundWhile it is accepted accurate identification of infecting organisms is crucial in guiding treatment of periprosthetic joint infection (PJI), there remains no consensus regarding the best method for obtaining cultures.Questions/purposesWe compared the yield of intraoperative tissue samples versus swab cultures in diagnosing PJI.MethodsTissue and swab cultures (three each) were collected prospectively during a consecutive series of 156 aseptic and septic revision arthroplasties from October 2011 to April 2012. The tissues and swabs were taken from standardized regions of the joint. After excluding 39 reimplantation procedures, we included 117 cases (74 hip, 43 knee; 30 septic, 87 aseptic) for analysis. We used a modified version of the Musculoskeletal Infection Society criteria for defining PJI, requiring three of five rather than four of six criteria. Tissue and swab cultures from septic and aseptic cases were used to calculate their sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for identifying PJI.ResultsTissue cultures were positive in a higher percentage of septic cases than swab cultures: 28 of 30 (93%) versus 21 of 30 (70%). Tissue cultures were positive in two of 87 aseptic cases (2%), while swab cultures were positive in 10 of 87 (12%). The sensitivity, specificity, PPV, and NPV were 93%, 98%, 93%, and 98%, respectively, for tissue cultures and 70%, 89%, 68%, and 90%, respectively, for swab cultures.ConclusionsTissue cultures demonstrated higher sensitivity, specificity, PPV, and NPV for diagnosing PJI than swab cultures. Swab cultures had more false-negative and false-positive results than tissue cultures. Because swab cultures pose a higher risk of not identifying or incorrectly identifying infecting organisms in PJI, we believe their use in obtaining intraoperative culture specimens should be discouraged.Level of EvidenceLevel II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Passing the Boards: can USMLE and Orthopaedic in-Training Examination scores predict passage of the ABOS Part-I examination?

Passing the written and oral examinations is a requirement for certification for the American Board of Orthopaedic Surgery (ABOS). Residents and residency program directors alike consider passing “The Boards” to be a priority. Part I of the ABOS examination consists of over 300 multiple-choice questions designed to test the candidates knowledge in general orthopaedics, basic science, and the application of this knowledge. Part II is an oral examination administered to evaluate the candidates competence in areas such as data gathering and interpretation, diagnosis, treatment, and technical skills. Passing the ABOS Part-I examination the first time is crucial to avoid delays in taking Part II and attaining board certification. In 2002, 553 (89%) of 623 first-time test-takers passed the ABOS Part-I examination. If one were to include repeat examinees, 637 (79%) of 805 passed1. The passing rate after one or more failures is dramatically lower than that for first-time examinees. In 2002, there were 182 repeat test-takers, of whom ninety-eight failed (a 54% failure rate), demonstrating the importance of passing the first time1. This suggests that inadequate training and preparation of an orthopaedic knowledge base for this examination during residency may be difficult to correct after an initial failure of the ABOS Part-I examination. The ABOS Part-I examination represents one standardized test in a long battery of examinations already taken by graduating residents, which include the Standardized Admission Test; Medical College Admission Test; United States Medical Licensing Examination (USMLE) Steps I, II, and III; and Orthopaedic In-Training Examination (OITE) administered during postgraduate-years (PGY)-1, 2, 3, 4, and 5. Since orthopaedic residency applications are extremely competitive (in 2000, there were 1116 candidates for 554 positions), it can be inferred that orthopaedic residents have generally performed well on these previous examinations2. Indeed, it may be the unofficial …

Total Joint Arthroplasty in Patients with Hepatitis C

BACKGROUND Hepatitis C is present worldwide. Little is known about the outcome of joint arthroplasty in asymptomatic patients with hepatitis C. We evaluated the surgical complications following hip and knee arthroplasty in patients who were seropositive for hepatitis C in a matched study. METHODS Seventy-one patients with hepatitis C underwent forty total hip arthroplasties and thirty-two total knee arthroplasties from 1995 to 2006. The patients had normal preoperative liver function tests. Patients with human immunodeficiency virus infection, hepatitis B, and hemophilia were excluded. A control group was matched in a 2:1 ratio with the hepatitis-C group for age, body-mass index, sex, year of surgery, and medical comorbidities, including diabetes, rheumatoid arthritis, and immunosuppressive conditions. RESULTS In the group of patients with hepatitis C who were managed with total hip arthroplasty, six patients (15%) had wound complications requiring oral antibiotics or wound irrigation and debridement and four hips (10%) had mechanical complications, including implant loosening or dislocation. In the control group, three patients (3.8%) had wound complications requiring oral antibiotics or irrigation and debridement and three patients (3.8%) had mechanical complications, including dislocation, periprosthetic femoral fracture, and implant failure. In the group of patients with hepatitis C who underwent total knee arthroplasty, three patients (9.4%) had mechanical complications, including loosening and periprosthetic fracture requiring revision. In the control group, three patients (4.7%) had wound complications, one (1.6%) had a deep infection requiring two-stage revision, and one (1.6%) underwent revision because of a mechanical problem. The combined hepatitis-C group had significantly longer hospital stays and higher rates of surgical and mechanical complications, reoperation, and revision. CONCLUSIONS Patients with hepatitis C undergoing joint arthroplasty had a higher rate of surgical complications and a longer hospital stay. The reason for the higher rate of complications in this group of patients is unknown, and further investigation is needed. Patients with hepatitis C should be counseled about the potential for a higher incidence of postoperative complications prior to undergoing joint arthroplasty.