Rare Bipolaris Species Fungal Periprosthetic Hip Infection in an Immunocompetent Host: A Case Report.

CASE: We present a case report of a 64-year-old man who developed a rare Bipolaris species fungal periprosthetic joint infection (PJI) after revision arthroplasty for complications associated with a metal-on-metal total hip arthroplasty. The patient underwent a 2-stage debridement with antibiotic bead placement and implant retention, along with chronic antifungal suppression. At the 2-year follow-up, the patient remained asymptomatic. CONCLUSION: Fungal PJI with filamentous fungi such as Bipolaris species is a rare clinical entity. This case report highlights the clinical presentation and management of this rare condition.

How Does Orthopaedic Surgeon Gender Representation Vary by Career Stage, Regional Distribution, and Practice Size? A Large-Database Medicare Study.

BACKGROUND: Orthopaedic surgery has the lowest proportion of women surgeons in practice of any specialty in the United States. Preliminary studies suggest that patients who are treated by physicians of the same race, ethnicity, cultural background, or gender feel more comfortable with their care and may have better outcomes. Therefore, understanding the discrepancies in the diversity of the orthopaedic surgeon workforce is crucial to addressing system-wide healthcare inequities. QUESTIONS/PURPOSES: (1) Does a difference exist in gender representation among practicing orthopaedic surgeons across geographic distributions and years in practice? (2) Does a difference exist in gender representation among practicing orthopaedic surgeons with regard to rural-urban setting, group practice size, and years in practice? METHODS: Orthopaedic surgeons serving Medicare patients in 2017 were identified in the Medicare Physician and Other Supplier Public Use File and Physician Compare national databases. This dataset encompasses more than 64% of practicing orthopaedic surgeons, providing a low proportion of missing data compared with other survey techniques. Group practice size, location, and Rural-urban Commuting Area scores were compared across physician gender and years in practice. Linear and logistic regressions modeled gender and outcomes relationships adjusted by years in practice. Least-square means estimates for outcomes were calculated by gender at the median years in practice (19 years) via regression models. RESULTS: According to the combined Medicare databases used, 5% (1019 of 19,221) of orthopaedic surgeons serving Medicare patients were women; this proportion increased with decreasing years in practice (R 2 0.97; p < 0.001). Compared by region, the West region demonstrated the highest proportion of women orthopaedic surgeons overall (7% [259 of 3811]). The Midwest and South regions were below the national mean for proportions of women orthopaedic surgeons, both overall (5% [305 of 6666] and 5% [209 of 4146], respectively) and in the first 5 years of practice (9% [54 of 574] and 9% [74 of 817], respectively). Women worked in larger group practices than men (median [interquartile range] 118 physicians [20 to 636] versus median 56 [12 to 338]; p < 0.001, respectively). Both genders were more likely to practice in an urban setting, and when controlling for years in practice, there was no difference between men and women orthopaedic surgeons practicing in rural or urban settings (respectively, R 2 = 0.0004 and 0.07; p = 0.89 and 0.09). CONCLUSION: Among orthopaedic surgeons, there is only one woman for every 20 men caring for Medicare patients in the United States. Although gender representation is increasing longitudinally for women, it trails behind other surgical subspecialties substantially. Longitudinal mentoring programs, among other evidenced initiatives, should focus on the more pronounced underrepresentation identified in Midwestern/Southern regions and smaller group practices. Gender-based equity, inclusion, and diversity efforts should focus on recruitment strategies, and further research is needed to study how inclusion and diversity efforts among orthopaedic surgeons improves patient-centered care. LEVEL OF EVIDENCE: Level III, therapeutic study.

Periosteal chondrosarcoma: an unusual juxtacortical sarcoma.

Periosteal chondrosarcoma is a rare tumor. It can be difficult to diagnose radiographically and pathologically and can be confused with periosteal osteosarcoma; however, the treatment of these two lesions is quite different. Increased awareness of imaging features of this lesion, particularly those that can help differentiate it from other surface-based tumors, can help one recognize this entity. We report the case of a periosteal chondrosarcoma in a young woman, highlighting the diagnostic imaging features of this disease, and her treatment with a joint-sparing geometric resection of the distal femur, using patient-specific 3D-printed cutting guides and matched allograft reconstruction.

What are the 2-year survivorship outcomes of custom hemipelvis reconstruction after hemipelvectomy and revision arthroplasty? The evolution of a custom ilium "monoflange".

BACKGROUND: Innovations in machined and three-dimensionally (3D) printed implant technology have allowed for customized complex pelvic reconstructions. We sought to determine the survivorship of custom hemipelvis reconstruction using ilium-only fixation at a minimum 2-year follow-up, their modes of failure, and the postoperative complications resulting from the procedure. METHODS: A retrospective review identified 12 consecutive patients treated with custom hemipelvis reconstruction. Indications for surgery were bone tumor requiring internal hemipelvectomy (four patients) or multiply revised, failed hip arthroplasty with massive bone loss (eight patients). All patients had a minimum of 2-year follow-up with a mean of 60.5 months. Kaplan-Meier survivorship analysis was determined for all patients. Postoperative complications and reoperations were categorized for all patients. RESULTS: At a mean of 60.5 months, 11 of 12 patients had retained their custom implant (92% survivorship). One implant was removed as a result of an acute periprosthetic joint infection (PJI). There were no cases of aseptic loosening. Seven of 12 patients required reoperation (three PJI; two dislocations; two superficial wound complications), with five patients going on to reoperation-free survival. CONCLUSIONS: Custom hemipelvis reconstruction utilizing an ilium monoflange provides durable short-term fixation at a minimum 2-year follow-up. Reoperation for infection and dislocation is common.

A Contemporary Classification System of Femoral Bone Loss in Revision Total Hip Arthroplasty.

BACKGROUND: Current femoral bone loss classification systems in revision total hip arthroplasty were created at a time when the predominant reconstructive methods used cylindrical porous-coated cobalt-chrome stems. As these stems have largely been replaced by fluted-tapered titanium stems, the ability of these classification systems to help guide implant selection is limited. The purpose of this study was to describe a novel classification system based on contemporary reconstructive techniques. METHODS: We reviewed the charts of all patients who underwent femoral component revision at our institution from 2007 through 2019. Preoperative images were reviewed, and FBL was rated according to the Paprosky classification and compared to ratings using our institution's NCS. Rates of reoperation at the time of most recent follow-up were determined and compared. RESULTS: Four-hundred and forty-two femoral revisions in 330 patients with a mean follow-up duration of 2.7 years were identified. Femoral type according to Paprosky and NCS were Paprosky I (36, 8.1%), II (61, 13.8%), IIIA (180, 40.7%), IIIB (116, 26.2%), and IV (49 11.1%) and NCS 1 (35, 7.9%), 2 (364, 82.4%), 3 (8, 1.8%), 4 (27, 6.1%), and 5 (8, 1.8%). Of the 353 nonstaged rTHAs, there were 42 cases requiring unplanned reoperation (11.9%), including infection (18, 5.1%), instability (10, 2.8%), femoral loosening (5, 1.4%), and various other causes (9, 2.5%). The NCS was more predictive of reoperation than the Paprosky classification (Fisher's exact test, P = .008 vs P = ns, respectively). CONCLUSION: We present a novel femoral classification system that can help guide contemporary implant selection.

Synovial fluid α defensin has comparable accuracy to synovial fluid white blood cell count and polymorphonuclear percentage for periprosthetic joint infection diagnosis.

AIMS: The aim of this study was to determine the diagnostic accuracy of α defensin (AD) lateral flow assay (LFA) and enzyme-linked immunosorbent assay (ELISA) tests for periprosthetic joint infection (PJI) in comparison to conventional synovial white blood cell (WBC) count and polymorphonuclear neutrophil percentage (PMN%) analysis. METHODS: Patients undergoing joint aspiration for evaluation of pain after total knee arthroplasty (TKA) or total hip arthroplasty (THA) were considered for inclusion. Synovial fluids from 99 patients (25 THA and 74 TKA) were analyzed by WBC count and PMN% analysis, AD LFA, and AD ELISA. WBC and PMN% cutoffs of ≥ 1,700 cells/mm3 and ≥ 65% for TKA and ≥ 3,000 cells/mm3 and ≥ 80% for THA were used, respectively. A panel of three physicians, all with expertise in orthopaedic infections and who were blinded to the results of AD tests, independently reviewed patient data to diagnose subjects as with or without PJI. Consensus PJI classification was used as the reference standard to evaluate test performances. Results were compared using McNemar's test and area under the receiver operating characteristic curve (AUC) analysis. RESULTS: Expert consensus classified 18 arthroplasies as having failed due to PJI and 81 due to aseptic failure. Using these classifications, the calculated sensitivity and specificity of AD LFA was 83.3% (95% confidence interval (CI) 58.6 to 96.4) and 93.8% (95% CI 86.2 to 98.0), respectively. Sensitivity and specificity of AD ELISA was 83.3% (95% CI 58.6 to 96.4) and 96.3% (95% CI 89.6 to 99.2), respectively. There was no statistically significant difference between sensitivity (p = 1.000) or specificity (p = 0.157) of the two AD assays. AUC for AD LFA was 0.891. In comparison, AUC for synovial WBC count, PMN%, and the combination of the two values was 0.821 (sensitivity p = 1.000, specificity p < 0.001), 0.886 (sensitivity p = 0.317, specificity p = 0.011), and 0.926 (sensitivity p = 0.317, specificity p = 0.317), respectively. CONCLUSION: The diagnostic accuracy of synovial AD for PJI diagnosis is comparable and not statistically superior to that of synovial WBC count plus PMN% combined. Cite this article: Bone Joint J 2021;103-B(6):1119-1126.

Modular Fluted Tapered Stems in Aseptic Oncologic Revision Total Hip Arthroplasty: A Game Changer?

BACKGROUND: Modular fluted tapered (MFT) stems are the most frequently used femoral component in revision total hip arthroplasties (THAs). Despite this, no data are available on how they perform in revision THA for oncologic salvage. This is a unique population, often with severe bone loss and prior radiation that extends the limits of uncemented femoral reconstruction. The aims of this study were to evaluate the implant survivorship, radiographic results, and clinical outcomes of MFT stems used for revision oncologic salvage. METHODS: We identified 17 patients treated initially with primary THA for an oncologic diagnosis (15 primary oncologic, 2 metastatic disease) who underwent subsequent femoral revision with an MFT stem. Mean age at revision was 66 years and 35% of patients were female. Mean follow-up was 4 years. Before revision, 5 of 17 had undergone local radiation. RESULTS: Ten-year survivorship free from aseptic loosening was 100%. The survivorship free of any reoperation was 76%. There were no femoral component fractures. Three patients were revised for recurrent instability, and 1 patient underwent irrigation and debridement for an acute infection. At most recent follow-up, no patient had radiographic evidence of progressive femoral component subsidence or failure of osteointegration. The mean Harris Hip Score improved from 29 preoperatively to 76 postoperatively (P < .0001). CONCLUSION: In this series of patients with cancer, many of whom had severe bone loss and/or prior local radiation, being treated with revision THA, there were no revisions for femoral component loosening and no cases of implant fracture. LEVEL OF EVIDENCE: III.

Screening for Periprosthetic Joint Infections With ESR and CRP: The Ideal Cutoffs.

BACKGROUND: The purpose of this study was to (1) determine the sensitivity and specificity of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) when screening for a periprosthetic joint infection (PJI) using the standard MSIS cutoff of 30 mm/h and 10 mg/L, respectively, and (2) determine the optimal ESR and CRP cutoff to achieve a sensitivity ≥95%. METHODS: We retrospectively analyzed 81 PJI patients and 83 noninfected arthroplasty patients. We calculated the sensitivity and specificity (and 95% confidence intervals) for ESR and CRP at thresholds of 30 mm/h and 10 mg/L, respectively. We determined the optimal cutoff for both ESR and CRP to yield a sensitivity greater than or equal to 95%. RESULTS: The ESR cutoff that resulted in a sensitivity ≥ to 95% (95% CI: 85.2-97.6%) was 10 mm/h, and the CRP cutoff that resulted in a sensitivity ≥ to 95% (95% CI: 87.1-98.4%) was 5 mg/L. The sensitivity and specificity with a combined ESR and CRP of 10 mm/h and 5 mg/L was 100% (95% CI: 94.1-100%) and 54.7% (95% CI: 46.4-62.3%). CONCLUSION: When using ESR and CRP as a screening tool with the accepted cutoffs of 30 mm/h and 10 mg/L, there is an unacceptably low sensitivity and a high number of false negatives. Therefore, further recommendation must be given to lowering these thresholds to avoid the devastating morbidity of a missed PJI. LEVEL OF EVIDENCE: III.

Frequency, Cost, and Clinical Significance of Incidental Findings on Preoperative Planning Images for Computer-Assisted Total Joint Arthroplasty.

BACKGROUND: The frequency of incidental findings with computer-assisted total joint arthroplasty (CA TJA) preoperative imaging and their clinical significance are currently unknown. METHODS: We reviewed 573 patients who underwent primary CA TJA requiring planning imaging. Incidental findings were defined as reported findings excluding those related to the planned arthroplasty. Secondary outcomes were additional tests or a delay in surgery. Associated charges were obtained from our institution's website. Charge and incidence data were combined with TJA volumes obtained from the 2016 National Inpatient Sample to model costs to the healthcare system. RESULTS: Overall, 262 patients (45.7%) had at least 1 incidental finding, 144 patients (25.1%) had 2, and 65 (11.3%) had 3. The most common finding types were musculoskeletal (MSK, 67.7%), digestive (19.5%), cardiovascular (4.9%), and reproductive (4.7%). Also, 9.3% of patients had at least 1 non-MSK incidental finding. Both MSK and non-MSK incidental findings were more common with total hip arthroplasty compared to total knee arthroplasty (67.9% vs 42.2%, P < .0001, and 15.4% vs 8.3%, P < .05, respectively). Further testing was required in 6 cases (1.0%); 1 case required delay in surgery (0.2%). Using the 2016 volume of TJA procedures and assuming a 10%, 15%, and 25%, utilization rate of image-based CA TJA, the annual cost of additional testing was $2.7 million (95% confidence interval, $1.1-$6.3 million), $4.1 million ($1.6-$9.5 million), and $6.9 million (95% confidence interval, $2.7-$15.8 million), respectively. CONCLUSION: Incidental findings are relatively common on planning images. Stakeholders should be aware of the hidden costs of incidental findings given the increasing popularity of image-based CA TJA.

Two-Stage Debridement With Prosthesis Retention for Acute Periprosthetic Joint Infections.

BACKGROUND: Historically, infection control rates with debridement and component retention have been poor in the management of acute prosthetic joint infections. We previously described a 2-stage debridement with prosthesis retention protocol for acute periprosthetic joint infection and reported a 90% success rate in a sample of 20 patients. METHODS: A retrospective review of 83 patients who underwent a 2-stage debridement with implant retention with a minimum 1-year follow-up was performed. Patient data were primarily analyzed to determine infection control rates. Infections were considered controlled when patients had not undergone a reoperation for infection, and demonstrated lack of any clinical signs or symptoms of infection (a well healed wound, diminishing swelling and warmth, absence of erythema, improvement in baseline pain symptoms) A secondary goal of this study was to examine the effects of symptom duration on infection control rate. RESULTS: Average patient follow-up was 41.8 months (range 12-171) for all patients. The overall protocol success rate was 86.7% (72/83): 82.9% in hips and 89.6% in knees. Additionally, protocol success was observed in 45 of 48 primary joints (93.8%) and 27 of 35 (77.1%) revision joints (P = .046). Average time from onset of symptoms to surgery was 6.2 days for successfully treated patients (range 0-27 days) compared to 10.7 days for those who failed treatment (range 1-28 days, P = .070). CONCLUSION: This 2-stage retention protocol resulted in a higher likelihood of infection control compared to prior reports of single stage debridement and modular part exchange.

The Alpha-Defensin Test for Diagnosing Periprosthetic Joint Infection in the Setting of an Adverse Local Tissue Reaction Secondary to a Failed Metal-on-Metal Bearing or Corrosion at the Head-Neck Junction.

BACKGROUND: In patients with adverse local tissue reaction (ALTR) secondary to a failed metal-on-metal (MoM) bearing or corrosion at the head-neck junction in a metal-on-polyethylene bearing, ruling in or out periprosthetic joint infection (PJI) can be challenging. Alpha-defensin has emerged as an accurate test for PJI. The purpose of this multicenter, retrospective study was to evaluate the accuracy of the alpha-defensin synovial fluid test in detecting PJI in patients with ALTR. METHODS: We reviewed medical records of 26 patients from 3 centers with ALTR that had an alpha-defensin test performed. Patients were assessed for PJI using the Musculoskeletal Infection Society criteria. Thirteen of these subjects had MoM total hip arthroplasty, 9 had ALTR secondary to head-neck corrosion, and 4 had MoM hip resurfacing. RESULTS: Only 1 of the 26 patients met Musculoskeletal Infection Society criteria for infection. However, 9 hips were alpha-defensin positive, including 1 true positive and 8 that were falsely positive (31%). All 8 of the false positives were also Synovasure positive, although 5 of 8 had an accompanying warning stating the results may be falsely positive due to a low synovial C-reactive protein value. CONCLUSION: Similar to synovial fluid white blood cell count, alpha-defensin testing is prone to false-positive results in the setting of ALTR. Therefore, we recommend an aggressive approach to ruling out PJI including routine aspiration of all hips with ALTR before revision surgery to integrate the synovial fluid blood cell count, differential, cultures and adjunctive tests like alpha-defensin to allow for accurate diagnosis preoperatively.

Surgeon Personal Protection: An Underappreciated Benefit of Positive-pressure Exhaust Suits.

BACKGROUND: Positive-pressure exhaust suits cost more than standard surgical gowns, and recent evidence suggests that they do not decrease infection risk. As a result, some hospitals and surgeons have abandoned positive-pressure exhaust suits in favor of less expensive alternatives. We propose that in addition to their original purpose of decreasing infection rates, positive-pressure exhaust suits may also improve personal protection for the surgeon and assistants, perhaps justifying their added costs. QUESTIONS/PURPOSES: (1) Do positive-pressure exhaust suits decrease exposure to particulate matter during TKA? (2) What areas covered by gowning systems are at risk of exposure to particulate matter? METHODS: Three surgical gowning systems were tested: (1) surgical gown, face mask, surgical skull cap, protective eyewear; (2) surgical gown, face mask, surgical protective hood, protective eyewear; and (3) positive-pressure exhaust suit. For each procedure, a cadaver knee was injected intraarticularly and intraosseously with a 5-µm fluorescent powder mixed with water (1 g/10 mL). After gowning in the standard sterile fashion, the primary surgeon and two assistants performed two TKAs with each gowning system for a total of six TKAs. After each procedure, three independent observers graded skin exposure of each surgical participant under ultraviolet light using a standardized scale from 0 (no exposure) to 4 (gross exposure). Statistical analysis was performed using Friedman's and Nemenyi tests. The interrater reliability for the independent observers was also calculated. RESULTS: The positive-pressure exhaust suits had less surgeon and assistant exposure compared with other systems (p < 0.001). The median overall exposure grade for each gowning system was 4 for System 1 (range, 3-4), 2.5 for System 2 (range, 2-3), and 0 for System 3 (range, 0-0). In pairwise comparisons between gowning systems, the positive-pressure exhaust suits had less exposure than gowning System 1 (difference of medians: 4, p < 0.001) and gowning System 2 (difference of medians: 2.5, p = 0.038). There was no difference found in exposure between Systems 1 and 2 (difference of medians: 1.5, p = 0.330). When gowning Systems 1 and 2 were removed, particulate matter was found in places that were covered such as the surgeon's beard, lips, inside the nostrils, behind the protective eyewear around the surgeon's eye, and in both eyebrows and eyelashes. CONCLUSIONS: The positive-pressure exhaust suits provided greater personal protection with each procedure than the other two gowning systems. CLINICAL RELEVANCE: With conventional gowns, particulate matter was found in the surgeon's eyelashes, under the face mask around the mouth, and inside the nostrils. Despite recent evidence that certain types of positive-pressure exhaust suits may not decrease infection, there is a clear benefit of surgeon protection from potentially infectious and harmful patient substances. Despite their added costs, hospitals and surgeons should weigh this protective benefit when considering the use of positive-pressure exhaust suits.

Compressive osseointegration endoprosthesis for massive bone loss in the upper extremity: surgical technique.

BACKGROUND: Reconstruction of large segments of bone loss can be very difficult. The use of a prestressed ingrowth implant can offer an attractive surgical option in these challenging cases. METHODS: This report describes the surgical technique in depth, combining the experience of the authors. Nuances of the technique are emphasized. RESULTS: Although published reports are uncommon, long-term restoration of extremity function is possible with this technology. CONCLUSIONS: The use of compressive osseointegration endoprostheses is not yet widespread in the upper extremity, but this technology adds to the host of surgical options for managing massive bone loss and difficult revision surgery.

Hemophilic pseudotumor in a non-hemophilic patient treated with a hybrid procedure of preoperative embolization of the feeding arteries followed by surgical resection-A case report.

INTRODUCTION: Hemophilic pseudotumor is a rare but well documented complication seen in approximately 1-2% of patients with hemophilia. The incidence continues to decrease, likely because of increasingly sophisticated techniques in managing factor deficiency. We present a case of hemophilic pseudotumor in a patient without hemophilia, an exceptionally rare entity, and outline a hybrid approach to treatment. PRESENTATION OF CASE: The patient presented with a left sided iliopsoas mass and associated radiculopathy, with a history of a poorly characterized bleeding diathesis and Noonan's syndrome. He had no history of trauma and was not being treated with anti-coagulation. Of note, factors VIII, IX and XI were normal. An open biopsy was consistent with hemophilic pseudotumor. The patient underwent a hybrid procedure of preoperative embolization of the left internal iliac and left deep circumflex arteries followed by surgical debridement and resection, with an excellent outcome. DISCUSSION: Hemophilic pseudotumor is rarely seen in patients with hemophilia, and even less frequently in patients without. Trauma is often the inciting event. A high index of clinical suspicion is required in order to secure the diagnosis, as the radiographic appearance is non-specific. Our patient had no history of trauma, although we question whether his underlying bleeding diathesis may have predisposed him to developing the pseudotumor. Surgery remains the cornerstone of management in these cases. CONCLUSION: Within the literature, there are only two other cases of hemophilic pseudotumor occurring in a non-hemophiliac patient, highlighting the rarity of this case and the associated diagnostic dilemma.

Leukocyte esterase analysis in the diagnosis of joint infection: can we make a diagnosis using a simple urine dipstick?

PURPOSE: Analysis of joint fluid remains a key factor in the diagnosis of periprosthetic infection. Recent reports have shown that neutrophils in infected joint fluid release esterase, an enzyme that is a reliable marker for infection. Testing for leukocyte esterase is routinely done in the analysis of urine for the presence of urinary tract infection, by a simple "dipstick" method. We report our experience with this technique in the evaluation of patients suspected of having septic arthritis or periprosthetic joint infection (PJI) by comparing results of leukocyte esterase positivity with confirmed joint infection as defined by the American Academy of Orthopaedic Surgeons (AAOS). MATERIALS AND METHODS: We retrospectively reviewed leukocyte esterase test results performed on synovial fluid aspirated from 57 patients with prosthetic (52) and native (5) joints. Patients either presented with unexplained painful arthroplasties, routine testing of PROSTALAC (PROSthesis with Antibiotic-Loaded Acrylic Cement) orthopedic implants, or clinical suspicion of periprosthetic infection or septic arthritis. Synovial fluid was percutaneously aspirated using a standard technique. The patient age range was 31-91 years with a mean age of 69.1 years, consisting of 30 women (52.6 %) and 27 men (47.4 %). The "gold standard" for the presence or absence of infection at our institution and in the study group was based on the most recent recommendations of the AAOS. Positive culture remained the "gold standard" for native joint infection. RESULTS: Of the total 57 joints aspirated and included in the study, 20 (35.1 %) were read as positive (2+) on the leukocyte test strip and 37 (64.9 %) were read as negative (negative, trace, or 1+). PJI was diagnosed in 19 patients and native joint septic arthritis was identified in one patient. Sensitivities were excellent at 100 % with no false negatives in the entire cohort. There was one false positive in the periprosthetic group yielding a specificity, positive predictive value and negative predictive value of 97, 95, and 100 %, respectively. The results for the native joints showed markedly less specificity and positive predictive value at 50 and 33 %; however, its negative predictive value remained at 100 %. CONCLUSIONS: Our test results confirm that the leukocyte esterase test can accurately detect PJI and that it can be used as a part of the traditional PJI workup. In the assessment of native joints, its high negative predictive value suggests that it is a valuable tool in excluding native joint septic arthritis.

Utility of percutaneous joint aspiration and synovial biopsy in identifying culture-positive infected hip arthroplasty.

PURPOSE: Percutaneous synovial biopsy has recently been reported to have a high diagnostic value in the preoperative identification of periprosthetic infection of the hip. We report our experience with this technique in the evaluation of patients undergoing revision hip arthroplasty, comparing results of preoperative synovial biopsy with joint aspiration in identifying an infected hip arthroplasty by bacteriological analysis. MATERIALS AND METHODS: We retrospectively reviewed the results of the 110 most recent revision hip arthroplasties in which preoperative synovial biopsy and joint aspiration were both performed. Revision surgery for these patients occurred during the period from September 2005 to March 2012. Using this study group, results from preoperative cultures were compared with preoperative laboratory studies and the results of intraoperative cultures. Synovial aspiration was done using an 18- or 20-gauge spinal needle. Synovial biopsy was done coaxially following aspiration using a 22-gauge Chiba needle or 21-gauge Sure-Cut needle. Standard microbiological analysis was performed on preoperative synovial fluid aspirate and synovial biopsy. Intraoperative tissue biopsy bacteriological analysis results at surgical revision were accepted as the "gold standard" for the presence or absence of infection. RESULTS: Seventeen of 110 (15 %) of patients had intraoperative culture-positive periprosthetic infection. Of these 17 cases, there were ten cases where either the synovial fluid aspiration and/or the synovial biopsy were true positive (sensitivity of 59 %, specificity of 100 %, positive predictive value of 100 % and accuracy of 94 %). There were seven cases where aspiration and biopsy results were both falsely negative, but no false-positive results. Similar results were found for synovial fluid aspiration alone. The results of synovial biopsy alone resulted in the identification of seven infected joints with no false-positive result (sensitivity of 41 %, specificity of 100 %, positive predictive value of 100 %, and accuracy of 91 %). CONCLUSIONS: Standard microbiological analyses performed on percutaneous synovial biopsy specimen during the preoperative evaluation of patients undergoing revision hip arthroplasty did not improve detection of culture-positive periprosthetic infection as compared to synovial fluid aspiration alone.

Compressive osseointegration into a custom acetabular implant masquerading as tumor recurrence: a case report.

BACKGROUND: Compressive osseointegration is a durable method of method of achieving fixation in long-bone reconstruction, and radiographic findings are well described. The radiographic appearance of integration into the pelvis is poorly defined in the available literature. CASE DESCRIPTION: We describe a 50-year-old man with a localized chondrosarcoma of the pelvis treated with wide resection and reconstruction using a custom acetabular device that used compressive osseointegration for fixation. A linear area of sclerosis was identified at the patient's 3-month followup surveillance film, which was concerning for tumor recurrence. We used PET-CT to document the absence of worrisome hypermetabolism and to support our suspicion that the abnormalities seen on a surveillance CT scan represented bony integration into the custom acetabular component rather than tumor recurrence. LITERATURE REVIEW: The use of FDG-PET for staging and surveillance of chondrosarcoma is presently evolving. Several articles suggest it may be useful in differentiating low-grade chondrosarcoma from benign lesions. PURPOSES AND CLINICAL RELEVANCE: We found PET-CT useful to differentiate the midterm radiographic appearance of the remodeling produced by compressive implant osseointegration from local recurrence.