Scott M. Sporer

Corrosion at the Head-Neck Taper as a Cause for Adverse Local Tissue Reactions After Total Hip Arthroplasty

BACKGROUND Corrosion at the modular head-neck junction of the femoral component in total hip arthroplasty has been identified as a potential concern, although symptomatic adverse local tissue reactions secondary to corrosion have rarely been described. METHODS We retrospectively reviewed the records of ten patients with a metal-on-polyethylene total hip prosthesis, from three different manufacturers, who underwent revision surgery for corrosion at the modular head-neck junction. RESULTS All patients presented with pain or swelling around the hip, and two patients presented with recurrent instability. Serum cobalt levels were elevated prior to the revision arthroplasty and were typically more elevated than were serum chromium levels. Surgical findings included large soft-tissue masses and surrounding tissue damage with visible corrosion at the femoral head-neck junction; the two patients who presented with instability had severe damage to the hip abductor musculature. Pathology specimens consistently demonstrated areas of tissue necrosis. The patients were treated with debridement and a femoral head and liner exchange, with use of a ceramic femoral head with a titanium sleeve in eight cases. The mean Harris hip score improved from 58.1 points preoperatively to 89.7 points at a mean of 13.0 months after the revision surgery (p=0.01). Repeat serum cobalt levels, measured in six patients at a mean of 8.0 months following revision, decreased to a mean of 1.61 ng/mL, and chromium levels were similar to prerevision levels. One patient with moderate hip abductor muscle necrosis developed recurrent instability after revision and required a second revision arthroplasty. CONCLUSIONS Adverse local tissue reactions can occur in patients with a metal-on-polyethylene bearing secondary to corrosion at the modular femoral head-neck taper, and their presentation is similar to the adverse local tissue reactions seen in patients with a metal-on-metal bearing. Elevated serum metal levels, particularly a differential elevation of serum cobalt levels with respect to chromium levels, can be helpful in establishing this diagnosis.

Perioperative Testing for Joint Infection in Patients Undergoing Revision Total Hip Arthroplasty

BACKGROUND While multiple tests are used to determine the presence of infection at the site of a total hip arthroplasty, few studies have applied a consistent algorithm to determine the utility of the various tests that are available. The purpose of the present study was to evaluate the utility of commonly available tests for determining the presence of periprosthetic infection in patients undergoing revision total hip arthroplasty. METHODS Two hundred and thirty-five consecutive total hip arthroplasties in 220 patients were evaluated by one of two surgeons using a consistent algorithm to identify infection and were treated with reoperation. Receiver-operating-characteristic curve analysis was used to determine the optimal cut-point values for the white blood-cell count and the percentage of polymorphonuclear cells of intraoperatively aspirated hip synovial fluid. Sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were determined. Patients were considered to have an infection if two of three criteria were met; the three criteria were a positive intraoperative culture, gross purulence at the time of reoperation, and positive histopathological findings. RESULTS Thirty-four arthroplasties were excluded because of the presence of a draining sinus, incomplete data, or a preoperative diagnosis of inflammatory arthritis, leaving 201 total hip arthroplasties available for evaluation. Fifty-five hips were judged to be infected. No hip in a patient with a preoperative erythrocyte sedimentation rate of <30 mm/hr and a C-reactive protein level of <10 mg/dL was determined to be infected. Receiver-operating-characteristic curve analysis of the synovial fluid illustrated optimal cut-points to be >4200 white blood cells/mL for the white blood-cell count and >80% polymorphonuclear cells for the differential count. However, when combined with an elevated erythrocyte sedimentation rate and C-reactive protein level, the optimal cut-point for the synovial fluid cell count was >3000 white blood cells/mL, which yielded the highest combined sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the tests studied. DISCUSSION A synovial fluid cell count of >3000 white blood cells/mL was the most predictive perioperative testing modality in our study for determining the presence of periprosthetic infection when combined with an elevated preoperative erythrocyte sedimentation rate and C-reactive protein level in patients undergoing revision total hip arthroplasty.

Changing demographics of patients with total joint replacement.

There has been a substantial change in the population demographics of patients who potentially will require total joint replacements. We studied data regarding temporal trends in physical condition, life expectancy, education, and other population demographics of individuals most likely to receive total joint replacements. Changes in this population during the last several decades correlate with temporal changes in the prevalence of joint disease and the incidence of total hip and knee replacements. Compared with several decades ago, patients currently receiving total joint replacements are almost 20% heavier, more physically active, three times more likely to have a high school or college education, and live more than 25% longer. Patients needing total joint replacements are more likely to be female, and twice as likely to receive a total knee replacement than a total hip replacement. Treatment choices and outcome expectations are best determined with accurate knowledge of current surgical science and current patient demographics. Therefore, it is important to realize that todays population most likely to receive total joint replacements is demographically different than in the past.

Comparison of Simultaneous Bilateral with Unilateral Total Knee Arthroplasty in Terms of Perioperative Complications

BACKGROUND Previous studies have demonstrated an increased rate of perioperative complications and morbidity following simultaneous bilateral total knee arthroplasty compared with the rate following unilateral total knee arthroplasty. The purpose of this study was to compare the rate of perioperative complications and morbidity associated with simultaneous bilateral total knee arthroplasty with that associated with unilateral total knee arthroplasty. METHODS The records on all bilateral total knee arthroplasties performed between January 1994 and June 2000 and unilateral total knee arthroplasties performed between January 1995 and June 2000 were retrospectively reviewed. The records on 514 unilateral total knee arthroplasties and 255 bilateral total knee arthroplasties were analyzed to determine demographic information, preoperative comorbidities, perioperative complications, and thirty-day and one-year mortality rates. RESULTS The rates of some perioperative complications, including myocardial infarction, postoperative confusion, and the need for intensive monitoring, were greater after the bilateral arthroplasties. However, the thirty-day and one-year mortality rates and the risks of pulmonary embolism, infection, and deep venous thrombosis were similar for the two groups. CONCLUSIONS The risk of perioperative complications associated with bilateral simultaneous total knee arthroplasty was slightly increased compared with that associated with unilateral total knee arthroplasty, but the mortality rates were similar. Ultimately, the decision to proceed with simultaneous knee replacement should depend on patient preference through informed choice.

Fracture of a Modular Femoral Neck After Total Hip Arthroplasty: A Case Report

The use of modularity in femoral stem designs for total hip arthroplasty has increased substantially over the past several years. The theoretical advantages of this design include the optimization of femoral anteversion, limb length, and offset of the femoral component. We report on a previously unreported fracture of a modular femoral neck device. The patient was informed that data concerning the case would be submitted for publication, and he consented. A forty-nine-year-old man underwent a primary total hip arthroplasty of the left hip, in June 2005, because of degenerative osteoarthritis and received a size-4 PROFEMUR Z femoral stem (Wright Medical Technology, Arlington, Tennessee) and a 64-mm CONSERVE acetabular component (Wright Medical Technology). The patient was 6 ft 6 in (198 cm) tall and weighed 340 lb (154.2 kg). An anterolateral surgical approach was utilized, and the bearing surface chosen was metal on metal. This proximal femoral cementless component is a dual-tapered rectangular stem that has a modular neck. The modular neck has an oval taper distally that is inserted into the femoral stem at a fixed angle. This allows the surgeon to independently adjust the offset and length as it is available in six different neck geometries and two lengths. Five different head options, ranging from –3.5 mm to +10.5 mm, are also available with this design. The head and neck are connected by means of a standard 12/14 Morse taper. Both the femoral stem and the modular neck are manufactured from a titanium alloy (Ti-6Al-4V). The patient had a 56-mm head with a –3.5-mm neck length. The neck geometry was a long varus anteverted neck (AR/VV2). The patient was otherwise healthy. The postoperative course was uneventful, and he was pain-free within three months after the procedure. In January 2009 (four years postoperatively), the patient slipped on ice and fell …

The Feasibility and Perioperative Complications of Outpatient Knee Arthroplasty

AbstractThe duration of hospitalization and subsequent length of recovery after elective knee arthroplasty have decreased. We hypothesized same-day discharge following either a unicompartmental (UKA) or total knee arthroplasty (TKA) in an unselected group of patients would not result in a higher perioperative complication rate than standard-length hospitalization when following a comprehensive perioperative clinical pathway, including preoperative teaching, regional anesthesia, preemptive oral analgesia, preemptive antiemetics, and a rapid rehabilitation protocol. We prospectively followed 111 of all 121 patients who had primary knee arthroplasty completed by noon and who agreed to be followed prospectively; 25 had UKA and 86 TKA. Of the 111 patients, 104 (94%, 24 with UKA and 80 with TKA) met discharge criteria and were discharged directly to home the day of surgery. Nausea requiring additional treatment before discharge was the most common reason for a delay in discharge. There were four (3.6%) readmissions (all with TKA) and one emergency room visit without readmission (in a patient with a TKA) within the first week after surgery, while there were four subsequent readmissions (3.6%) and one additional emergency room visit without readmission within three months of surgery, all among patients undergoing TKA. There were no deaths, cardiac events, or pulmonary complications during this study. Outpatient knee arthroplasty surgery is feasible in a large percentage of patients yet early readmissions may be decreased with a prolonged hospitalization. Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Newer Anesthesia and Rehabilitation Protocols Enable Outpatient Hip Replacement in Selected Patients

Advancements in the surgical approach, anesthetic technique, and the initiation of rapid rehabilitation protocols have decreased the duration of hospitalization and subsequent length of recovery following elective total hip arthroplasty. We assessed the feasibility and safety of outpatient total hip arthroplasty in 150 consectutive patients. A comprehensive perioperative anesthesia and rehabilitation protocol including preoperative teaching, regional anesthesia, and preemptive oral analgesia and antiemetic therapy was implemented around a minimally invasive surgical technique. A rapid rehabilitation pathway was started immediately after surgery and patients had the option of being discharged to home the day of surgery if standard discharge criteria were met. All 150 patients were discharged to home the day of surgery, at which time 131 patients were able to walk without assistive devices. Thirty-eight patients required some additional intervention outside the pathway to resolve nausea, hypotension, or sedation prior to discharge. There were no readmissions for pain, nausea, or hypotension yet there was one readmission for fracture and nine emergency room evaluations in the three month perioperative period. This anesthetic and rehabilitation protocol allowed outpatient total hip arthroplasty to be routinely performed in these consectutive patients undergoing primary total hip arthroplasty. With current reimbursement approaches the modest savings to the hospital in length of stay may be outweighed by the additional costs of personnel, thereby making this outpatient system more expensive to implement.Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Serum and Synovial Fluid Analysis for Diagnosing Chronic Periprosthetic Infection in Patients with Inflammatory Arthritis

BACKGROUND The serum erythrocyte sedimentation rate and C-reactive protein level, as well as the synovial fluid white blood-cell count with differential, are commonly used tests for the diagnosis of periprosthetic joint infection; however, their utility for the diagnosis of periprosthetic joint infection in patients with inflammatory arthritis is unknown. METHODS Eight hundred and three patients undergoing 871 consecutive hip and knee arthroplasties (including sixty-one in patients with inflammatory arthritis and 810 in patients with noninflammatory arthritis) were prospectively evaluated for periprosthetic joint infection. The erythrocyte sedimentation rate, C-reactive protein level, and synovial fluid white blood-cell count with differential were obtained routinely. Receiver operating characteristic curves were used to establish optimal thresholds for the diagnosis of periprosthetic joint infection, and the area under the curve was calculated to determine the overall accuracy of these tests for patients with inflammatory compared with noninflammatory arthritis. RESULTS The utility of all serum and synovial tests for predicting chronic periprosthetic joint infection was similar for patients with noninflammatory and inflammatory arthritis. The optimal cutoffs in patients with noninflammatory and inflammatory arthritis were 32 and 30 mm/hr, respectively, for the erythrocyte sedimentation rate; 15 and 17 mg/L, respectively, for the C-reactive protein level; 3450/μL and 3444/μL, respectively, for the synovial fluid white blood-cell count; and 78% and 75%, respectively, for the differential. The areas under the curves were similar for the two groups (84.9% and 85.0%, respectively, for the erythrocyte sedimentation rate; 88.5% and 85.1%, respectively, for the C-reactive protein level; 94.5% and 93.8%, respectively, for the synovial fluid white blood-cell count, and 95.0% and 93.6%, respectively, for the differential). Finally, the sensitivities, specificities, negative predictive values, and positive predictive values for all tests were also comparable in both groups. The rate of periprosthetic joint infection was significantly higher following procedures in patients with inflammatory arthritis than following procedures in patients with noninflammatory arthritis (31% compared with 18%; p = 0.013). CONCLUSIONS The erythrocyte sedimentation rate, C-reactive protein level, and synovial fluid white blood-cell count with differential are useful for diagnosing periprosthetic joint infection in patients with inflammatory as well as noninflammatory arthritis, with similar optimal cutoff values and overall testing performance. The synovial fluid white blood-cell count and differential performed the best for the diagnosis of periprosthetic joint infection. Physicians evaluating patients with a failed or painful total hip or knee arthroplasty should not assume that elevation of the erythrocyte sedimentation rate, C-reactive protein level, and synovial fluid white blood-cell count with differential is secondary to inflammatory arthropathy; rather, elevation of these markers may indicate periprosthetic joint infection, and further evaluation for infection is warranted.

Dilute Betadine Lavage Before Closure for the Prevention of Acute Postoperative Deep Periprosthetic Joint Infection

This study evaluated the efficacy of a dilute Betadine (Purdue Pharma, Stamford, Conn) lavage in preventing early deep postoperative infection after total hip (THA) and knee (TKA) arthroplasty. A protocol of dilute Betadine lavage (0.35%) for 3 minutes was introduced to the practice of the senior author in June 2008. A total of 1862 consecutive cases (630 THA and 1232 TKA) performed before this were compared with 688 consecutive cases (274 THA and 414 TKA) after for the occurrence of periprosthetic infections within the first 90 days postoperatively. Eighteen early postoperative infections were identified before the use of dilute Betadine lavage, and 1 since (0.97% and 0.15%, respectively; P = .04). There were no significant demographic differences between the 2 groups. Betadine lavage before wound closure may be an inexpensive, effective means of reducing acute postoperative infection after total joint arthroplasty.

Ankle fractures in the elderly: what you get depends on where you live and who you see.

Objectives: This study was performed to determine 1) the rate of ankle fractures in the elderly in the United States stratified by hospital referral region, and 2) whether the percentage of ankle fractures treated surgically is affected by factors, such as fracture location, hospital referral region, concentration of orthopaedists, presence of a teaching hospital in that region, patient age, race, gender, or the number and type of specific medical comorbidities. Design: A 20% sample of Medicare Part B claims from the years 1998 to 2000 was analyzed. Patients/Intervention: The CPT codes for operative and nonoperative treatment of isolated medial malleolar, isolated lateral malleolar, bimalleolar, and trimalleolar fractures were identified. These codes were used to determine the overall rate of ankle fractures and individual fracture types. Main Outcome Measurement: The rate of ankle fractures was evaluated by hospital referral region, patient age (groups of 5 years, aged 65 years or older), gender, and race. The percentage of surgical treatment was determined for each fracture type as the number of surgically treated fractures over the total number of ankle fractures within each subtype and analyzed by fracture type, hospital referral region, and concentration of orthopaedists in that region, presence of a teaching hospital within the hospital service area, patient age, gender, race, and number and type of specific medical comorbidities. Regression was performed by using the above variables. Results: We identified 33,704 ankle fractures: 7.6% were isolated medial malleolar, 50.8% were isolated lateral malleolar, 27.4% were bimalleolar, and 14.2% were trimalleolar fractures. The overall United States average was 4.2 ankle fractures per 1000 Medicare enrollees. The rate of ankle fractures varied by a factor of 8, from 1 per 1000 Medicare enrollees in San Francisco, CA, to 8.3 in Hickory, NC. The rate of ankle fractures was highest in white women at 5.8 and lowest in nonwhite men at 1.5 per 1000 Medicare enrollees. The overall rate of ankle fractures that underwent surgical stabilization was 33%, ranging from 14% in Binghampton, NY, to 72% in Napa, CA. The rate of surgical intervention was 22% for isolated medial malleolar fractures, 11% for isolated lateral malleolar fractures, 58% for bimalleolar fractures, and 74% for trimalleolar fractures. In regression analysis, the factors associated with nonoperative care after ankle fracture were: older age, female gender, increasing number of comorbidities as measured by the Charlson index, presence of diabetes or peripheral vascular disease, and living in a hospital service area that had a designated teaching hospital. Beneficiaries living in areas in which a hospital was a member of the Council of Teaching Hospitals were less likely to receive surgical treatment of their ankle fracture. Increasingly older age was strongly associated with decreased likelihood of having surgical intervention, with each 5 year age grouping progressively less likely to have surgical treatment. The concentration of orthopaedists in the region was not associated with the likelihood of having surgical treatment. Conclusions: The term ankle fracture involves a wide spectrum of injuries. We found a large variation through the United States in both the rate of ankle fractures and the percentage of those that undergo surgical intervention.