Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Published in
Clinical Orthopaedics and Related Research®
Volume 467 | Issue 7 | Jul, 2009

Diabetes Associated with Increased Surgical Site Infections in Spinal Arthrodesis

Sam Chen MD, Matt V. Anderson BS, Wayne K. Cheng MD, Montri D. Wongworawat MD Diabetes mellitus (DM) is a major risk factor for surgical site infection (SSI). Spinal surgeries are also associated with an increased risk of SSI. To confirm previous reports we evaluated the association of DM with spine infection in 195 patients who underwent elective posterior instrumented lumbar arthrodesis over a 5-year period: 30 with DM and 165 without. Other known risk factors for SSI in spinal surgery were examined: age, gender, tobacco use, body mass index, American Society of Anesthesiologists (ASA) class, intraoperative antibiotic redosing, surgical time, bone allograft use, estimated blood loss (EBL), and drain use. The adjusted relative risk of having DM for developing SSI was 4.10 (95% C.I. = 1.37–12.32). Other factors did not appear as risk factors for SSI. The data confirm DM is a risk factor for surgical site infections in spinal arthrodesis surgery.,[object Object]

Effectiveness of Antimicrobial Incise Drapes versus Cyanoacrylate Barrier Preparations for Surgical Sites

Sepehr Bady MD, Montri D. Wongworawat MD Surgical wound infections are one of the leading causes of morbidity and mortality in surgical patients. We compared the effectiveness of antimicrobial incise drapes versus cyanoacrylate microbial sealant adhesive barrier in preventing skin flora contamination of surgical wounds in an animal model. Staphylococcus aureus in suspension was placed on fresh ovine skin across 60 circular marks of defined area: 20 circles were designated as controls, 20 were covered with antimicrobial incise drapes, and 20 were covered with cyanoacrylate. Incisions were made through the circles; swab cultures were taken, serially diluted after agitation, and cultured on blood agar plates. The number of colony forming units (CFUs) was then counted and compared between the samples from the two drapes. While there were no differences between antimicrobial incise-draped areas (108.3 ± 90 CFUs) and undraped controls (82.7 ± 93.3 CFUs), the cyanoacrylate-treated group demonstrated lower wound bed contamination (0.3 ± 0.6 CFUs) when compared to controls.

Topographic Features Retained after Antibiotic Modification of Ti Alloy Surfaces: Retention of Topography with Attachment of Antibiotics

Constantinos Ketonis BS, Javad Parvizi MD, Christopher S. Adams PhD, Irving M. Shapiro DDS, PhD, Noreen J. Hickok PhD [object Object]

Magnetic Resonance Imaging Findings in Hematogenous Osteomyelitis of the Hip in Adults

Charalampos G. Zalavras MD, Nick Rigopoulos MD, John Lee MD, Thomas Learch MD, Michael J. Patzakis MD Hematogenous hip infections are rare in adults and the extent of infection into the bone or adjacent soft tissues may be underestimated, leading to inadequate surgical débridement. Using MRI, we sought to determine the extent of bone involvement and the presence of adjacent soft tissue abscesses in adults with hip osteomyelitis. We reviewed the records and MRIs in 11 adult patients (12 hips) with hematogenous osteomyelitis of the femoral head in 12 hips. Ten of 11 patients had one or more comorbidities. All patients underwent surgical débridement and received antibiotic therapy for 6 weeks. MRI revealed osteomyelitis distal to the femoral head in seven of 12 hips with extension into the medullary canal in three of these seven. Femoral head erosions were present in 10 hips, acetabulum osteomyelitis in 11, and acetabular erosions in six hips. Infection extended into adjacent soft tissues in eight of 12 hips. MRI demonstrated that the infection may extend distal to the femoral head or into the adjacent soft tissues. MRI may be useful for preoperative planning so that all regions affected by the infection can be treated.,[object Object]

Hand-mixed and Premixed Antibiotic-loaded Bone Cement Have Similar Homogeneity

Alex C. McLaren MD, Matt Nugent MD, Kostas Economopoulos MD, Himanshu Kaul BSE, Brent L. Vernon PhD, Ryan McLemore PhD Since low-dose antibiotic-loaded bone cement (ALBC) was approved by the FDA for second-stage reimplantation after infected arthroplasties in 2003, commercially premixed low-dose ALBC has become available in the United States. However, surgeons continue to mix ALBC by hand. We presumed hand-mixed ALBC was not as homogeneous as commercially premixed ALBC. We assessed homogeneity by determining the variation in antibiotic elution by location in a batch, from premixed and hand-mixed formulations of low-dose ALBC. Four hand-mixed methodologies were used: (1) suspension—antibiotic powder in the liquid monomer; (2) no-mix—antibiotic powder added but not mixed with the polymer powder before adding monomer; (3) hand-stirred—antibiotic powder stirred into the polymer powder before the monomer was added; and (4) bowl-mix—antibiotic powder mixed into polymer powder using a commercial mixing bowl before the monomer was added. Antibiotic elution was measured using the Kirby-Bauer bioassay. None of the mixing methods had consistently dissimilar homogeneity of antibiotic distribution from the others. Based upon our data we conclude hand-mixed low-dose ALBC is not less homogeneous than commercially premixed formulations.

Staged Revision for Knee Arthroplasty Infection: What Is the Role of Serologic Tests Before Reimplantation?

Elie Ghanem MD, Khalid Azzam MD, Mark Seeley MD, Ashish Joshi MD, MPH, Javad Parvizi MD, FRCS Erythrocyte sedimentation rate and C-reactive protein are common preoperative diagnostic markers for prosthetic joint infection but their prognostic role before reimplantation has yet to be defined. We therefore determined the prognostic value of erythrocyte sedimentation rate and C-reactive protein performed before second-stage reimplantation for the treatment of infected total knee arthroplasty (TKA). We studied 109 patients who had undergone two-stage revision TKA for sepsis from 1999 to 2006. Receiver operating characteristic curves were constructed to determine the discriminatory value of erythrocyte sedimentation rate and C-reactive protein before reimplantation in predicting persistent infection. Twenty-three of the 109 patients (21%) required revision surgery for recurrence of prosthetic joint infection. The receiver operating characteristic areas under the curve suggested erythrocyte sedimentation rate and C-reactive protein poorly predicted persistent infection after TKA reimplantation. Cutoff values could not be obtained because of the high variance. We reached similar conclusions regarding the change in erythrocyte sedimentation rate and C-reactive protein levels from time of resection. More accurate diagnostic tools are needed to support clinical judgment in monitoring infection progress and thus deciding whether to proceed with TKA reimplantation.,[object Object]

Outcome of a Second Two-stage Reimplantation for Periprosthetic Knee Infection

Khalid Azzam MD, Kevin McHale BA, Matthew Austin MD, James J. Purtill MD, Javad Parvizi MD Recurrent or persistent infection after two-stage exchange arthroplasty for previously infected total knee replacement is a challenging clinical situation. We asked whether a second two-stage procedure could eradicate the infection and preserve knee function. We evaluated 18 selected patients with failed two-stage total knee arthroplasty implantation treated with a second two-stage reimplantation between 1999 and 2005. Failure of treatment was defined as recurrence or persistence of infection. The minimum followup was 24 months (mean, 40 months; range, 24–83 months). Recurrent or persistent infection was diagnosed in four of 18 patients, two of whom were successfully treated with a third two-stage exchange arthroplasty. Knee Society score questionnaires administered at the last followup showed an average Knee Society knee score of 73 points (range, 24–100 points) and an average functional score of 49 points (range, 20–90 points). The data suggest repeat two-stage exchange arthroplasty is a reasonable option for eradicating periprosthetic infection, relieving pain, and achieving a satisfactory level of function for some patients.,[object Object]

Infection Following Operative Treatment of Ankle Fractures

Charalampos G. Zalavras MD, Thomas Christensen MD, Nikolaos Rigopoulos MD, Paul Holtom MD, Michael J. Patzakis MD

Information on the microbiology of infections after operative ankle fractures, on the details of a treatment protocol used when the ankle joint is preserved, and on the outcome of this protocol will be helpful for the physicians managing patients with this complex problem. We therefore determined the most common pathogen of these infections, the infection recurrence rate, and the amputation rate. We retrospectively reviewed 26 patients of a mean age of 43 years with infections following operative treatment of ankle fractures. Twenty-one of 26 patients (81%) were compromised hosts according to the Cierny-Mader classification. Patients presenting up to 10 weeks postoperatively were treated by débridement and either hardware retention (if implants were judged stable) or hardware removal (if implants were loose). All patients presenting more than 10 weeks postoperatively underwent débridement and hardware removal, with the exception of one patient who underwent below knee amputation. Staphylococcus aureus was identified in 17 patients (65%) and was oxacillin-resistant in six (23%). The infection recurred in five of 18 patients who were followed up for 8 months on average. Three recurrent infections were controlled with repeat débridement. The remaining two patients underwent below-knee amputation, resulting in amputations in 3 of 18 patients. Infection after operative treatment of ankle fractures is a limb-threatening complication, especially in patients with comorbidities, such as diabetes mellitus. Treatment is challenging with high infection recurrence and amputation rates.,[object Object]

Hip Disarticulation for Severe Lower Extremity Infections

Charalampos G. Zalavras MD, Nick Rigopoulos MD, Elke Ahlmann MD, Michael J. Patzakis MD Hip disarticulation is rarely performed for infections and variable mortality rates have been reported. We determined the number of deaths following hip disarticulation for severe lower extremity infections in 15 patients. Indications for hip disarticulation were necrotizing soft tissue infections in seven patients and persistent infections of the proximal thigh in eight patients. The most common microorganism was Staphylococcus aureus, present in eight patients. Hip disarticulation was performed emergently in seven patients and electively in eight patients. All patients survived the operation and at 1 month postoperatively 14 of 15 patients were alive. Hip disarticulation for these severe infections had high survival, even when performed emergently for life-threatening infections. We believe hip disarticulation is a reasonable option treating severe infections of the lower extremity and should be part of the armamentarium of the orthopaedic surgeon.,[object Object]

Patients with Prosthetic Joint Infection on IV Antibiotics are at High Risk for Readmission

Anurag Duggal MD, Wael Barsoum MD, Steven K. Schmitt MD Due to the rise in prosthetic joint implantations, prosthetic joint infections (PJI) are increasing. Most PJI are treated outside the hospital setting via community-based parenteral antiinfective therapy (CoPAT) after initial surgical management, although little is reported about the short-term complications of CoPAT. We therefore ascertained the numbers of unanticipated readmissions, unplanned surgeries, and CoPAT complications within 12 weeks of hospital discharge in patients with PJI on CoPAT. We retrospectively reviewed the charts of 74 patients with PJI. Twenty-seven (73% of readmitted patients) were for unanticipated reasons within 12 weeks of hospital discharge; 16 (43% of readmitted) underwent an unplanned surgery. Nine patients (12% of total cohort) had CoPAT-related adverse events. Our data suggest patients with PJI on CoPAT represent a complex cohort that needs to be monitored closely for complications early after hospital discharge.,[object Object]

Periprosthetic Infection Due to Resistant Staphylococci: Serious Problems on the Horizon

Javad Parvizi MD, FRCS, Khalid Azzam MD, Elie Ghanem MD, Matthew S. Austin MD, Richard H. Rothman MD, PhD Prosthetic joint infections (PJI) caused by methicillin-resistant staphylococci represent a major therapeutic challenge. We examined the effectiveness of surgical treatment in treating infection of total hip or knee arthroplasty caused by methicillin-resistant staphylococcal strains and the variables influencing treatment success. One hundred and twenty-seven patients were treated at our institution between 1999 and 2006. There were 58 men and 69 women, with an average age of 66 years. Patients were followed for a minimum of 2 years or until recurrence of infection. Débridement and retention of the prosthesis was performed in 35 patients and resection arthroplasty in 92. Débridement controlled the infection in only 37% of cases whereas two-stage exchange arthroplasty controlled the infection in 75% of hips and 60% of knees. Preexisting cardiac disease was associated with a higher likelihood of failure to control infection in all treatment groups. Antibiotic-resistant Staphylococci continue to compromise treatment outcome of prosthetic joint infections, especially in patients with medical comorbidities. New preventive and therapeutic strategies are needed.,[object Object]

Adjacent Segment Instability after Treatment with a Graf Ligament at Minimum 8 Years’ Followup

Yongsoo Choi MD, Kisoo Kim MD, Kwangyoung So MD Although there has been some enthusiasm over the early clinical results obtained using the Graf ligament, associated mid- to long-term results are controversial. We retrospectively reviewed 43 patients (67 segments) treated with the Graf ligament for degenerative lumbar stenosis. The minimum followup was 8 years (mean, 10 years; range, 8–14 years). At last followup, we observed angular instability in 19 of the 67 segments (28%) and translational instability in five (7%). The disc height decreased from postoperatively (mean 93% of the preoperative disc) to the final followup (mean 82%). Of the 43 patients, 18 (42%) had adjacent segmental instability at the upper segment, including angular instability in 11 patients, translational instability in four patients, and both in three patients. The adjacent segment instability at the lower segment revealed 13 patients (30%) with angular instability. The data suggest the anticipated mechanical effects of the Graf ligament can be altered by degeneration of the disc and facet joints at instrumented segments and the adjacent segment can be affected, perhaps as a result of abnormal load transmission.,[object Object]

The Relationship Between Skeletal Muscle Serum Markers and Primary THA: A Pilot Study

Russell G. Cohen MD, Jay A. Katz MD, Nebojsa V. Skrepnik MD, PhD Various reports confirm elevations in serum markers associated with skeletal muscle injury after orthopaedic surgery in the absence of overt clinical manifestations of myocardial injury. We therefore measured the influence surgical approach has on these serum markers after primary THA. We nonrandomly enrolled 30 nonconsecutive patients undergoing THA in three groups of 10 based on current surgical approaches used at our facility: (1) minimally invasive (MIS) modified Watson Jones approach; (2) miniposterior transmuscular approach (MIS-I); and (3) MIS-II incision. Blood samples for hemoglobin, hematocrit, cardiac troponin I, total creatine kinase, creatine phosphokinase, and serum myoglobin were obtained the morning before surgery as a baseline, immediately postoperatively, and 72 hours thereafter. We found reproducible trends in serum enzyme levels consistent with skeletal muscle damage resulting from primary THA. Troponin I remained normal in all but one patient indicating no myocardial contribution to measured serum enzyme levels. All three procedures resulted in similar trends in serum enzyme markers relevant to primary THA. Our preliminary data suggest no surgical approach appears to affect the degree of muscle trauma more or less than another.

Cemented Polyethylene Cups in Patients Younger Than 40 Years

Daniël C. J. Kam MD, Jean W. M. Gardeniers MD, PhD, Jan C. M. Hendriks PhD, René P. H. Veth MD, PhD, B. Willem Schreurs MD, PhD Although uncemented cup implants frequently are used in young patients, we believe long-term survival rates of cups in these patients are somewhat disappointing, and therefore we have continued to use cemented cups in primary THA, even in young patients. However, in cases of acetabular bone stock defects, we also use bone impaction grafting. We prospectively followed 130 patients with 175 cemented cups; no patients were lost to followup. The mean age of the patients at surgery was 31 years (range, 16–39 years). An acetabular reconstruction with bone impaction grafting was performed in 84 hips (48%). The minimum followup was 2 years (average, 8.1 years; range, 2.0–18.5 years). Twenty-one of the 175 cups (12%) were revised at an average of 8.1 years (range, 2.0–18.5 years). Reasons for revision were infection (one early, seven late), recurrent dislocations (two), traumatic loosening (one), and aseptic loosening (10). The 10-year survival rate of all cemented cups with end point of revision for any cause was 85%. Survival with end point of aseptic loosening of all cups was 92%. Survival with end point of revision for aseptic loosening was 90% for the cups without impaction grafting and 95% for the cups with impaction grafting. We believe cemented acetabular cups in young patients have acceptable midterm survival; however, in the case of acetabular bone defects, we recommend reconstruction with impaction grafting.,[object Object]

Wear is Reduced in THA Performed with Highly Cross-linked Polyethylene

Burak Beksaç MD, Antonio Salas MD, Alejandro González Della Valle MD, Eduardo A. Salvati MD Highly cross-linked polyethylene (HCLPE) has been used extensively to decrease osteolysis and related implant failure in THA. We compared the wear rate of HCLPE and noncross-linked conventional PE (CPE) liners and the rate of radiographic calcar resorption and osteolysis in young patients (35–60 years of age) who underwent THA by one surgeon. Thirty-four patients (41 THAs) who received a hybrid THA using a HCLPE liner were match-paired for age, gender, body mass index, and diagnosis with a group of patients who underwent THA with identical implants but with a CPE liner. The minimum followup was 4 years (average, 5.3; range, 4–8 years). Using the Livermore measurement technique, the averages of total wear of the HCLPE and CPE liners were 0.01 mm (range, −0.23–0.4) and 0.64 mm (range, 0–1.7), respectively. The average annual wear was less for the HCLPE than the noncross-linked PE (0.002 mm, range, −0.05–0.1 versus 0.12 mm, range, 0–0.29, respectively). Four hips in the HCLPE group and 23 in the CPE group had calcar resorption measuring averages of 2.5 mm (range, 2–3) and 7.5 mm (range, 1.8–23.8), respectively. Periprosthetic osteolysis occurred in two and eight hips in the HCLPE and CPE groups, respectively. Longer followup is needed to determine if these findings will result in improved implant survivorship.,[object Object]

VKORC1 Variant Genotypes Influence Warfarin Response in Patients Undergoing Total Joint Arthroplasty: A Pilot Study

Alejandro González Della Valle MD, Saurabh Khakharia MD, Charles J. Glueck MD, Nicole Taveras BS, MS, Ping Wang PhD, Robert N. Fontaine PhD, Eduardo A. Salvati MD Warfarin dosing algorithms do not account for genetic mutations that can affect anticoagulation response. We retrospectively assessed to what extent the VKORC1 variant genotype would alter the likelihood of being a hyperresponder or hyporesponder to warfarin in patients undergoing total joint arthroplasty. We used the international normalized ratio (INR) on the third postoperative day of 3.0 or greater to define warfarin hyperresponders and 1.07 or less to define hyporesponders. A control group of normal responders was identified. From a cohort of 1125 patients receiving warfarin thromboprophylaxis, we identified 30 free of predisposing factors that could affect warfarin response: 10 hyperresponders, eight hyporesponders, and 12 normal responders. Homozygous carriers of the VKORC1 mutant AA genotype were more likely (compared with carriers of GA or GG genotypes) to be hyperresponders (odds ratio, 7.5; 95% confidence interval, 1.04–54.1). Homozygous carriers of the GG (normal) genotype were more likely (compared with carriers of AA or GA genotypes) to be hyporesponders (odds ratio, 9; 95% confidence interval, 1.14–71). Preoperative screening for the VKORC-1 genotype could identify patients with a greater potential for being a hyperresponder or hyporesponder to warfarin. This may allow an adjusted pharmacogenetic-based warfarin dose to optimize anticoagulation, reducing postoperative risks of bleeding and thrombosis or embolism.,[object Object]

Ten-year Results of an Inset Biconvex Patella Prosthesis in Primary Knee Arthroplasty

Sani Erak MBBS, FRACS, Vaishnav Rajgopal MD, Steven J. MacDonald MD, FRCSC, Richard W. McCalden MD, FRCSC, Robert B. Bourne MD, FRCSC The inset biconvex patella component is an alternative form of patella resurfacing in knee arthroplasty. We retrospectively reviewed 433 patients in whom 521 patella prostheses were implanted before April 1997 to determine survivorship, factors associated with failure of the implant, incidence of anterior knee pain, and factors that may be associated with the latter. We had clinical results for 204 surviving patients (242 knees) without failure of their implants with a minimum 10-year followup (mean, 11.4 years; range, 10–17 years). For the remaining 229 patients we used chart or radiographic review to determine if failure of their implant or other complications had occurred. At latest followup, 14 patella components had been revised for aseptic reasons or were radiographically loose. The 10-year Kaplan-Meier survivorship for the entire cohort for aseptic failure was 97.0%. Aseptic failure of the patella component was associated with the presence of osteonecrosis and the absence of a superior rim of bone radiographically. The incidence of anterior knee pain in surviving patients without failure of their implants was 7.8%. No factor examined was associated with anterior knee pain. Survivorship and clinical and radiographic results are equivalent, but not clearly superior, to those reported for other forms of patella resurfacing.,[object Object]

Does Prior Infection Alter the Outcome of TKA After Tibial Plateau Fracture?

A. Noelle Larson MD, Arlen D. Hanssen MD, Joseph R. Cass MD Total knee arthroplasty performed after tibial plateau fracture has a known high rate of complications. We hypothesized TKAs performed after infected tibial plateau fractures would have an even higher complication rate when compared with noninfected tibial plateau fractures. In a matched case-control study, we retrospectively reviewed 19 patients who underwent primary TKAs after infected tibial plateau fractures between 1971 and 2005. The mean time from the most recent infection to arthroplasty was 5.6 years. The minimum clinical followup after TKA was 2 years (mean, 6.4 years; range, 2–15.1 years). Case patients were matched for age, gender, and arthroplasty year with 19 control subjects who underwent TKAs for tibial plateau fractures with no history of infections. After surgery, the Knee Society scores for the study group improved from 45 to 63 for pain and from 37 to 63 for function. Ten case patients (53%) sustained complications, including surgery for wound breakdown (three), manipulation (one), aseptic loosening (two), definitive resection arthroplasty (two), and above-knee amputation (two). Recurrent infections occurred in five patients (26%) at a mean of 1.1 years. Previously infected knees were 4.1 times more likely to require additional procedures compared with knees with no previous infection.,[object Object]

Etiology of Ankle Osteoarthritis

Victor Valderrabano MD, PhD, Monika Horisberger MD, Iain Russell MD, Hugh Dougall MD, Beat Hintermann MD The purpose of this study was to evaluate the distribution rate of etiologies leading to ankle arthritis and to quantify and compare the important clinical and radiologic variables among these etiologic groups. We evaluated data from 390 patients (406 ankles) who consulted our center because of painful end-stage ankle osteoarthritis (OA) by using medical history, physical examination, and radiography. Posttraumatic ankle OA was seen in 78% of the cases (n = 318), secondary arthritis in 13% (n = 52), and primary OA in 9% (n = 36). The average American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score was 38 points (range, 0–74 points), range of motion was 22° (range, 0°−65°), and visual analog scale for pain was 6.8 (range, 2–10). Patients with posttraumatic end-stage ankle OA were younger than patients with primary OA. The average tibiotalar alignment was 88° (range, 51°–116°) and did not differ between the etiologic groups. Our study showed trauma is the main cause of ankle OA and primary OA is rare. In the majority of patients with ankle OA the average tibiotalar alignment is varus regardless of the underlying etiology.,[object Object]

A New Radiographic Measurement Method for Evaluation of Tibial Torsion: A Pilot Study in Adults

Melih Güven MD, Budak Akman MD, Koray Ünay MD, Engin Kutay Özturan MD, Hüsamettin Çakıcı MD, Abdullah Eren MD Computed tomography (CT) frequently is used to determine torsional abnormalities. However, its use in clinical practice may be limited. We present a new method for measuring tibial torsion using conventional radiographs. We compared the method with several clinical methods and with CT measurement in 44 lower extremities of 25 subjects. The radiographic method agreed well with all of the clinical methods, and this agreement was better than agreement between CT and clinical examination. The best agreement was between thigh-foot angle and the radiographic method. The proposed radiographic measurement is a practical method for evaluation of tibial torsion in outpatient clinics without the need for specialized equipment.,[object Object]

Telescope Allograft Method to Reconstitute the Diaphysis in Limb Salvage Surgery

John H. Healey MD, Ayesha Abdeen MD, Carol D. Morris MD, Edward A. Athanasian MD, Patrick J. Boland MD We propose a surgical technique for structural allograft reconstitution of the diaphysis of long bones, maximizing surface contact between host and allograft bone. This method, analogous to a telescope, overlaps the graft and host bone, theoretically increasing bone surface contact substantially. We report the outcome of 22 telescoped allograft junction sites in 19 patients who lacked sufficient host bone to accommodate a regular-length stemmed implant. This joint-sparing reconstruction preserved 15 of 16 adjacent joints at risk for replacement. Five patients needed additional surgery, but none for nonunion. The diaphyseal length could be reconstructed enough so that a short prosthesis (less than the critical 40% of total bone length) could be used. This biologic method to reconstruct major segments of the diaphysis is best suited for patients with quantitatively or qualitatively deficient residual bone stock after tumor resection or prosthetic revision. We believe it is an excellent technique for revision knee megaprostheses when there is a short remnant of proximal femur.,[object Object]

Infarct-associated Bone Sarcomas

Gregory F. Domson MD, Amir Shahlaee MD, John D. Reith MD, Charles H. Bush MD, C. Parker Gibbs MD Sarcoma associated with bone infarct is a rare condition sparsely reported in the literature. Sixty percent of cases arise about the knee and most are malignant fibrous histiocytomas. We report 15 patients; 12 of 15 presented with a tumor around the knee. Treatment was limb salvage in seven patients, amputation in six, and biopsy alone in two. For patients without metastatic disease at presentation, the 2-year disease-free survival rate was 63% (seven of 11). Two patients received chemotherapy and both were continuously disease-free at last followup. When we combined our 15 patients with the 52 previously reported in the literature, 38 of the 67 (57%) died of their disease at an average of 19.2 months after diagnosis; 21 patients (31%) were continuously disease-free for 24 months. Of 13 patients who received chemotherapy, eight (62%) were continuously disease-free at 24 months compared with 24% (13 of 54) of those who did not receive chemotherapy. Overall, prognosis for these patients is poor, but survival in patients without metastatic disease at diagnosis approaches that of other bone sarcomas. There is a trend suggesting adjuvant chemotherapy combined with appropriate surgery may improve patient outcomes.,[object Object]

Pyrolytic Carbon Endoprosthetic Replacement for Osteonecrosis and Femoral Fracture of the Hip: A Pilot Study

Thomas L. Bernasek MD, Jennifer L. Stahl BS, Derek Pupello MBA Hemiarthroplasty in young patients has the potential for eliminating bearing wear, but has the disadvantage of cartilage wear. Low-temperature isotropic (LTI) pyrolytic carbon reportedly reduces cartilage wear in canine hemiarthroplasties. We therefore initiated a study in humans when it was released for human use. However, we observed failures in some patients. We therefore document and report the high failure rate observed in a subset of patients treated with an LTI pyrolytic carbon femoral head for osteonecrosis. We conducted a prospective pilot study of 17 patients treated with a titanium stem and an LTI pyrolytic carbon femoral head bearing surface for unipolar hemiarthroplasty for either femoral neck fracture (10 patients) or osteonecrosis (seven patients). One of 10 patients in the fracture group underwent conversion to THA as a result of arthritic progression compared with six of seven patients with osteonecrosis who underwent conversion to THA as a result of acetabular wear and severe groin pain. In this small series, patients with osteonecrosis had a higher rate of revision compared with the patients treated for femoral neck fracture.,[object Object]

Computer-navigated Iliosacral Screw Insertion Reduces Malposition Rate and Radiation Exposure

Jörn Zwingmann MD, Gerhard Konrad MD, Elmar Kotter MD, Norbert P. Südkamp Prof, Michael Oberst MD Insertion of percutaneous iliosacral screws with fluoroscopic guidance is associated with a relatively high screw malposition rate and long radiation exposure. We asked whether radiation exposure was reduced and screw position improved in patients having percutaneous iliosacral screw insertion using computer-assisted navigation compared with patients having conventional fluoroscopic screw placement. We inserted 26 screws in 24 patients using the navigation system and 35 screws in 32 patients using the conventional fluoroscopic technique. Two subgroups were analyzed, one in which only one iliosacral screw was placed and another with additional use of an external fixator. We determined screw positions by computed tomography and compared operation time, radiation exposure, and screw position. We observed no difference in operative times. Radiation exposure was reduced for the patients and operating room personnel with computer assistance. The postoperative computed tomography scan showed better screw position and fewer malpositioned screws in the three-dimensional navigated groups. Computer navigation reduced malposition rate and radiation exposure.,[object Object]

Differentially Loaded Radiostereometric Analysis to Monitor Fracture Stiffness: A Feasibility Study

Mellick J. Chehade MBBS, PhD, Lucian B. Solomon MD, PhD, Stuart A. Callary BAppSc, Sam H. Benveniste MBBS, Anthony P. Pohl MBBCh, MD, Donald W. Howie MBBS, PhD Inability to accurately and objectively assess the mechanical properties of healing fractures in vivo hampers clinical fracture management and research. We describe a method to monitor fracture stiffness during healing in a clinical research setting by detecting changes in fracture displacement using radiostereometric analysis and simultaneously measuring applied axial loads. A method was developed for load application, positioning of the patient, and radiographic setup to establish the technique of differentially loaded radiostereometric analysis (DLRSA). A DLRSA examination consists of radiostereometric analysis radiographs taken without load (preload), under different increments of load, and without load (postload). Six patients with distal femur fractures had DLRSA examinations at 6, 12, 18, and 26 weeks postoperatively. The DLRSA method was feasible in a clinical setting. The method provides objective and quantifiable data for internally fixed fractures and may be used in clinical research as a tool to monitor the in vivo stiffness of healing femoral fractures managed with nonrigid internal fixation.

Two-stage Cementless Revision of Infected Hip Endoprostheses

Bernd Fink MD, Alexandra Grossmann, Martin Fuerst MD, Peter Schäfer MD, Lars Frommelt MD Cementless two-stage revision of infected total hip prostheses lacks the possibility of local antibiotic protection of the implant at the time of reimplantation, which leads to the concern that this protocol may not sufficiently eradicate periprosthetic infection. Moreover, early implant loosening as much as 18% and stem subsidence as much as 30% have been reported. To determine whether a cementless revision could eradicate infection and achieve sufficient implant stability, we prospectively followed 36 patients with two-stage revisions for septic hip prostheses. We used a uniform protocol of a 6-week spacer interval, specific local and systemic antibiotic therapies, and cementless modular revision stems. The minimum followup was 24 months (mean, 35 months; range, 24–60 months). In one patient, the spacer was changed when the C-reactive protein value failed to normalize after 6 weeks, and the reimplantation was performed after an additional 6 weeks. No infections recurred. There was no implant loosening and a 94% bone-ingrowth fixation of stems. Subsidence occurred in two patients. The Harris hip score increased from a preoperative mean of 41 to 90 at 12 months after reimplantation and later. Using cementless prostheses in two-stage revisions of periprosthetic infections of the hip in combination with a specific local and systemic antibiotic therapy seems to eradicate infection and provide implant stability.,[object Object]

Relationship Between Perioperative Urinary Tract Infection and Deep Infection After Joint Arthroplasty

Panagiotis Koulouvaris MD, PhD, Peter Sculco MS, Eileen Finerty RN, Thomas Sculco MD, Nigel E. Sharrock MB, ChB Surgical wound infection is a serious and potentially catastrophic complication after joint arthroplasty. Urinary tract infection is a common infection that creates a potential reservoir of resistant pathogens and increases patient morbidity. We asked whether treated preoperative and postoperative urinary tract infections are risk factors for deep joint infection. We examined the medical records of 19,735 patients. The minimum had joint infections develop. Of these, three had preoperative and four had postoperative urinary tract infections. The majority of bacteria were not enteric. The bacteria in the two types of infections were not identical. Control subjects were randomly selected from a list of patients matched with patients having infections. Of these, eight had preoperative and one had postoperative urinary tract infections. We found no association between the preoperative urinary tract infection (odds ratio, 0.341; 95% confidence interval, 0.086–1.357) or postoperative urinary tract infection (odds ratio, 4.222; 95% confidence interval, 0.457–38.9) and wound infection. Only one of the 58 patients with wound infections had a urinary tract infection with the same bacteria in both infections. Given the infection rate was very low (0.29%), the power of the study was only 25%. Although limited, the data suggest patients with urinary tract infections had no more likelihood of postoperative infection. We believe treated urinary tract infection should not be a reason to delay or postpone surgery.,[object Object]

Performance of a Sterile Meniscal Allograft in an Ovine Model

Allison G. McNickle MS, Vincent M. Wang PhD, Elizabeth F. Shewman MS, Brian J. Cole MD, MBA, James M. Williams PhD Meniscus transplantation is indicated for persistent pain in a meniscectomized knee. Currently, grafts are prepared aseptically, which provides limited protection against donor-derived infection. The performance of a novel, sterilized meniscus was compared with an aseptically prepared one in an experimental model. Twenty-two sheep were divided into three groups: aseptic meniscal allograft, sterile meniscal allograft, and medial meniscectomy. Animals were euthanized 2 and 4 months after surgery. Meniscal assessments included cell viability, histology, and biomechanical testing. Articular cartilage was evaluated through histology and Outerbridge scoring. Aseptic and sterile allografts had cell viabilities of 59.7% and 58.7%, respectively, at 4 months, which was less than native controls. Grafts had decreased compressive strength at 4 months compared with their preimplantation moduli and were weaker than native menisci. In operated knees, the tibial plateau had more severe degenerative changes, although Outerbridge scores were similar between operated groups. Overall, the allografts were similar in their cellularity and biomechanical properties but were inferior to the native tissue at these end points. The severity of chondral damage in the allograft knees could not be distinguished from meniscectomized joints. The sterilization process does not appear to compromise tissue integrity and provides additional allograft safety.

Chondrocyte Apoptosis after Simulated Intraarticular Fracture: A Comparison of Histologic Detection Methods

Alexis C. Dang MD, Hubert T. Kim MD, PhD Accurate evaluation of programmed cell death, or apoptosis, in chondrocytes is essential to studying cartilage injury. We evaluated four methods of detecting chondrocyte-programmed cell death in formalin-fixed, paraffin-embedded cartilage after experimental osteochondral fracture. Human osteochondral explants were subjected to experimental fracture in a manner known to induce high levels of chondrocyte-programmed cell death. After 4 days in culture, specimens were fixed and analyzed for programmed cell death using: (1) terminal deoxynucleotidyl transferase end labeling; (2) DNA denaturation analysis using an antibody specific for single-stranded DNA; (3) immunohistochemistry using antisera specific for active caspase-3; and (4) in situ oligonucleotide ligation. Quantitative analysis of programmed cell death levels for each technique was performed comparing injured and uninjured areas of cartilage. We observed differences between injured and uninjured areas of cartilage using the four methods. Human cartilage fixed in zinc-formalin and embedded in paraffin is amenable to programmed cell death analysis using any of four independent methods, each of which ostensibly has some advantages in terms of assaying different steps along the apoptotic pathway. Using the protocols described in this article, investigators may have additional tools to identify and quantify chondrocytes undergoing programmed cell death after experimental cartilage injury.

2009 Nicolas Andry Award: Clinical Biomechanics of Third Body Acceleration of Total Hip Wear

Thomas D. Brown PhD, Hannah J. Lundberg PhD, Douglas R. Pedersen PhD, John J. Callaghan MD Aseptic loosening attributable to wear-related osteolysis historically has been the predominant cause of failure in THA. Advances in low-wear bearing couples show great promise to substantially reduce this long-standing problem. However, there always has been striking variability in wear rate in any given cohort of patients who are similarly implanted, with some individuals typically experiencing near order-of-magnitude elevations above group mean. Third-body wear is likely a major contributor to many of these most osteolysis-prone outliers. For the patients affected, third-body effects may obviate many of the gains otherwise achieved by contemporary bearing surface improvements. Toward heightening visibility in terms of consequences for patients, this review paper summarizes an interrelated series of investigations quantifying construct level manifestations of third-body wear. Long-term followup of a unique group of patients with elevated third-body challenge shows statistically significant and clinically important wear-rate increases. A series of finite element models, validated physically, shows the linkage of location of third-body damage with variability of volumetric wear-rate acceleration and shows the effects of various implant factors, surgeon factors, and patient factors in the presence of third-body challenge. Finally, a mechanism for third-body debris access to wear-critical locations on the bearing surface is identified analytically and corroborated in laboratory experiments and implant retrievals.

2009 Marshall Urist Young Investigator Award: How Often Do Patients with High-Flex Total Knee Arthroplasty Use High Flexion?

James I. Huddleston MD, Donna Moxley Scarborough MS, PT, Dov Goldvasser MScE, Andrew A. Freiberg MD, Henrik Malchau MD, PhD Although high-flexion TKA designs aim to safely accommodate deep flexion, it is unknown how often patients use deep flexion outside the laboratory. We used a validated smart-activity monitor to document the prevalence of knee flexion greater than 90° in 20 consecutive patients (21 knees) who had high-flexion TKAs, at a minimum of 2 years’ followup. Patients wore the device continuously for a mean of 35.7 ± 0.5 hours. The 21 knees flexed more than 90° for an average of 10 ± 3.8 minutes (0.5%). Activities performed with flexion greater than 90° were, on average, 70% in single-limb stance, 12% moving from sitting to standing, 8% walking, 7% moving from standing to reclining, 2% stepping, 0.9% moving from lying to standing, and 0.1% running. Eight knees flexed greater than 120° for an average of 2.2 minutes (range, 0.2–15 minutes), or 0.1% of the testing time. Activities performed with flexion greater than 120° were, on average, 90% in single-limb stance, 6% moving from sitting to standing, 3% walking, 0.6% moving from standing to reclining, 0.3% stepping, and 0.1% moving from lying to standing. Peak flexion used at any time during testing was, on average, 84% ± 11% of maximum postoperative flexion (125° ± 12°). These patients rarely used deep flexion.,[object Object]

Case Report: Histologic Study of a Human Epiphyseal Transplant at 3 Years after Implantation

J. Sales de Gauzy MD, F. Accadbled MD, PhD, A. Gomez Brouchet MD, A. Abid MD A 5-year-old boy underwent surgical excision of a Ewing’s sarcoma of the proximal femur. Reconstruction was performed using an ipsilateral vascularized epiphyseal transplant and a femoral allograft. Local recurrence of the tumor necessitated hip disarticulation 3 years after the initial procedure. We then performed a histologic analysis of the transplant. The growth plate was still normal in structure but had richly vascularized hyperplastic layers. We observed bridging between the articular cartilage and the growth plate.

Case Reports: Two Femoral Insufficiency Fractures after Long-term Alendronate Therapy

Arkan S. Sayed-Noor MD, FEBOT, PhD, Göran O. Sjödén MD, PhD Bisphosphonates are widely used for treatment of postmenopausal osteoporosis. Although short-term safety and efficacy of these drugs have been investigated and documented, an increasing number of recent reports draw attention to the possible correlation between long-term alendronate therapy and the occurrence of insufficiency fractures in the proximal femur owing to what is known as severely suppressed bone turnover. We describe two femoral insufficiency fractures in two women receiving long-term alendronate therapy. The first woman sustained a periprosthetic fracture at the tip of the femoral stem whereas the other woman had a fracture in the subtrochanteric region. We analyze the characteristics and natural course of these two unique fractures, and emphasize the importance of being aware of the possible correlation between long-term alendronate therapy and insufficiency femoral fractures.

Erratum: THA with a Minimally Invasive Technique, Multi-modal Anesthesia, and Home Rehabilitation: Factors Associated with Early Discharge?

Dana Christopher Mears MD, PhD, Simon C. Mears MD, PhD, Jacques E. Chelly MD, PhD, MBA, Feng Dai PhD, Katie L. Vulakovich
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