Adam J. Schwartz

The Alpha Defensin-1 Biomarker Assay can be Used to Evaluate the Potentially Infected Total Joint Arthroplasty

BackgroundDiagnosing a periprosthetic joint infection (PJI) requires a complex approach using various laboratory and clinical criteria. A novel approach to diagnosing these infections uses synovial fluid biomarkers. Alpha defensin-1 (AD-1) is one such synovial-fluid biomarker. However little is known about the performance of the AD-1 assay in the diagnosis of PJI.Questions/purposesWe sought to (1) determine the sensitivity and specificity of the AD-1 assay in a population of patients being evaluated for PJI, using the Musculoskeletal Infection Society (MSIS) criteria as the reference standard, and (2) compare the AD-1 assay with other currently available clinical tests, specifically cell count, culture, erythrocyte sedimentation rate, and C-reactive protein.Patients and MethodsA retrospective review was performed of all patients undergoing workup for a PJI at our institution from January to June 2013. Sixty-one AD-1 assays were done in 57 patients. The group included 51 patients with 55 painful joints and six patients who underwent aspiration before second-stage reimplantation. Patients were considered to have a PJI if they met the MSIS criteria. We calculated the sensitivity and specificity of the AD-1 synovial fluid assay, and compared it with the sensitivity and specificity of the synovial fluid cell count, culture, erythrocyte sedimentation rate, and C-reactive protein. There were 19 diagnosed infections in the 61 aspirations, with 21 positive and 40 negative AD-1 assays. There were two false positive and no false negatives AD-1 assays.ResultsThe sensitivity and specificity for the AD-1 assay were 100% (95% CI, 79%–100%) and 95% (95% CI, 83%–99%), respectively. The sensitivity and specificity of the other tests ranged from 68% to 95% and 66% to 88%, respectively. The AD-1 assay results outperformed the other tests but did not reach statistical significance except for the sensitivity of the erythrocyte sedimentation rate.ConclusionThe sensitivity and specificity of the synovial fluid AD-1 assay exceeded the sensitivity and specificity of the other currently available clinical tests evaluated here but did not reach significance. The AD-1 assay offers another test with high sensitivity and specificity for diagnosing a PJI especially in the case where the diagnosis of PJI is uncertain, but larger studies will be needed to determine significance and cost effectiveness.Level of EvidenceLevel III, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

Cemented Endoprosthetic Reconstruction of the Proximal Tibia: How Long Do They Last?

BackgroundThe few available studies documenting the long-term survival of cemented proximal tibial endoprostheses for musculoskeletal tumors do not differentiate between stem designs or patient diagnosis. There is wide variation in survival rates reported, possibly a result of this heterogeneity in patient population and implant design.Questions/purposesWe therefore asked: (1) How long do proximal tibial endoprostheses last? (2) What is the typical long-term functional result after proximal tibial replacement? And (3) what are the short- and long-term complications associated with endoprosthetic reconstruction of the proximal tibia, particularly with respect to the soft tissue reconstruction?Patients and MethodsWe retrospectively reviewed 52 patients with 52 proximal tibial endoprosthetic reconstructions for a tumor-related diagnosis. Kaplan-Meier survivorship analysis was performed using revision of the stemmed components for any reason as an endpoint for implants, and death due to disease progression for patients. Function was assessed using the MSTS scoring system. The minimum followup was 1 month (mean, 96 months: range, 1–284 months; median, 69 months).ResultsUsing revision of the stemmed components for any reason as an end point, overall prosthesis survival at 5, 10, 15, and 20 years was 94%, 86%, 66%, and 37%, respectively. The 29 modular implants demonstrated a trend toward improved survival compared to the 23 custom-designed components, with a 15-year survivorship of 88% versus 63%. The mean postoperative Musculoskeletal Tumor Society score at most recent followup was 82% of normal function (mean raw score, 24.6; range, 4–29).ConclusionsCemented endoprosthetic reconstruction of the proximal tibia provides a reliable method of reconstruction following tumor resection.Level of Evidence Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Neoadjuvant chemoradiation compared to neoadjuvant radiation alone and surgery alone for Stage II and III soft tissue sarcoma of the extremities.

BackgroundNeoadjuvant chemoradiation (NCR) prior to resection of extremity soft tissue sarcoma (STS) has been studied, but data are limited. We present outcomes with NCR using a variety of chemotherapy regimens compared to neoadjuvant radiation without chemotherapy (NR) and surgery alone (SA).MethodsWe conducted a retrospective chart review of 112 cases.ResultsTreatments included SA (36 patients), NCR (39 patients), and NR (37 patients). NCR did not improve the rate of margin-negative resections over SA or NR. Loco-regional relapse-free survival, distant metastases-free survival, and overall survival (OS) were not different among the treatment groups. Patients with relapsed disease (OR 11.6; p = 0.01), and tumor size greater than 5 cm (OR 9.4; p = 0.01) were more likely to have a loco-regional recurrence on logistic regression analysis. Significantly increased OS was found among NCR-treated patients with tumors greater than 5 cm compared to SA (3 year OS 69 vs. 40%; p = 0.03). Wound complication rates were higher after NCR compared to SA (50 vs. 11%; p = 0.003) but not compared to NR (p = 0.36). Wet desquamation was the most common adverse event of NCR.ConclusionsNCR and NR are acceptable strategies for patients with STS. NCR is well-tolerated, but not clearly superior to NR.

How Long Do Endoprosthetic Reconstructions for Proximal Femoral Tumors Last

BackgroundAs the life expectancy of patients with musculoskeletal tumors improves, long-term studies of endoprosthetic reconstructions are necessary to establish realistic expectations for the implants and compare them to other reconstruction approaches.Questions/purposes(1) What is the long-term survival of cemented bipolar proximal femoral replacements? (2) How does prosthesis survival compare to patient survival among patients with Stage I, II, and III disease? (3) Do modular implants outperform custom-built prostheses? (4) Do some proximal femoral replacements require conversion to THA?Patients and MethodsWe retrospectively reviewed all 86 proximal femoral replacements used for tumor reconstruction from 1982 to 2008. Primary diagnoses were 43 high-grade tumors (IIA/IIB), 20 low-grade tumors (IA/IB or benign), and 23 with metastatic disease. We reviewed prosthesis survival, patient survival, complication rates, functional outcomes, and rates of conversion to THA.ResultsFive of 86 patients (5.8%) required revision of the femoral component. Five-, 10-and 20-year implant survivorships were 93%, 84%, and 56%, respectively. All patients with low-grade disease survived; the 5-year survival rate for patients with metastatic disease was 16%; the 5-, 10-, and 20-year survival for IIA/IIB patients was 54%, 50%, and 44%, respectively. Five of 86 patients (5.8%) underwent conversion to THA for groin pain.ConclusionsCemented bipolar proximal femoral replacements after tumor resection proved a durable reconstruction technique. The implants outlived patients with metastatic disease and high-grade localized disease while patients with low-grade disease outlived their implants. The survival of modular prostheses was comparable to that of older, one-piece custom designs.Level of Evidence Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Predictive factors of wound complications after sarcoma resection requiring plastic surgeon involvement.

IntroductionThe most effective management of a patient with sarcoma is surgical resection. Often the resection is performed, the wound is irradiated, adjuvant chemotherapy is administered, and the wound is closed without plastic surgery consultation. Wound complications, after these treatment protocols, often require plastic surgery involvement and the treatment may require more advanced reconstructive techniques with higher rates of complications than if involvement occurred earlier. MethodsA retrospective review of all patients who underwent sarcoma excision from 2001 to 2011 was performed. Factors such as tumor size, radiation, chemotherapy, delayed reconstruction (>3 weeks), and immediate reconstruction (<3 weeks) were analyzed for their correlation with wound complications or flap loss. ResultsA total of 127 patients underwent sarcoma resection. Wound complications occurred in 49 (38%) patients. All 15 delayed reconstructions had a wound complication, whereas only 11 (37%) of immediate reconstructions had a wound complication. Wound complications with tissue excision less than 500 g occurred in 18 (26%) patients and occurred in 31 (54%) patients with excision greater than 500 g. Seventy-two patients underwent radiation with a wound complication rate of 46% compared with 29% for patients who were not radiated. Chemotherapy was used in 35 patients with a wound complication rate of 49%. ConclusionsThe most predictive factor of sarcoma complication is whether the procedure was a delayed or immediate reconstruction. The second most predictive factor is the amount of tissue excised, greater than 500 g of tissue excised was associated with significantly higher complication rates. Other aspects of sarcoma treatment that may be correlated with higher incidence of wound complications are radiation and the use of adjuvant chemotherapy. Early plastic surgery involvement can help with preoperative planning and reduce the complication rates in patients with sarcoma resection.

Use of Compressive Osseointegration Endoprostheses for Massive Bone Loss From Tumor and Failed Arthroplasty: A Viable Option in the Upper Extremity

BackgroundEndoprostheses using principles of compressive osseointegration have shown good survivorship in several studies involving the lower extremity; however, no series to our knowledge have documented the use of this technology in the management of massive bone loss in the upper limb.Questions/purposes(1) What proportion of upper extremity implants using compressive osseointegration fixation principles achieved durable short-term fixation, and what were the modes of failure? (2) What surgical complications resulted from reconstruction using this technique?MethodsA multiinstitutional retrospective review identified nine patients (five women; four men) who underwent 13 endoprosthetic replacements between 2003 and 2014 using compressive osseointegration (Compliant® Pre-stress Device [CPS]; Biomet Inc, Warsaw, IN, USA) in the upper extremity, including two proximal humeri, two humeral diaphyses, seven distal humeri, and two proximal ulna. During the early part of that period, the indication for use of a compressive prosthesis in our centers was revision of a previous tumor reconstruction (allograft-prosthetic composite or stemmed endoprosthetic reconstruction) (three patients; five implants), or revision arthroplasty with massive bone loss (three patients, four implants); more recently, indications became somewhat more permissive and included posttraumatic bone loss (one patient, one implant), primary bone sarcoma, and resections with very short remaining end segments after diaphyseal resections (two patients, three implants). Minimum followup was 24 months; one patient (one implant) was lost to followup before that time with the implant intact at 14 months and no patients have died. The mean age of the patients was 45 years (range, 21–62 years). Mean followup was 68 months (range, 24–141 months). Implant revision for any cause and for failure of the CPS mechanism was recorded. Modes of failure were categorized as soft tissue, aseptic loosening, structural, infection, and tumor progression; CPS modes of failure were defined as lack of fixation, with or without bone or implant fracture.ResultsOf the 12 implants accounted for beyond 2 years, six had undergone revision of any kind. Only two revisions in two patients were attributable to lack of CPS fixation at the bone-implant interface; one of the patients also had periprosthetic and implant fracture develop through the traction bar. Other modes of failure were aseptic loosening of the standard ulnar component (two patients, two implants), bushing wear (one patient; one implant) and infection resulting in two-stage exchange and free soft tissue transfer with retention of the CPS spindle (one patient, one implant). Complications for all nine patients included one transient radial nerve palsy, one ulnar nerve sensory neurapraxia, one superficial infection, and two glenohumeral subluxations, one underwent revision surgery with implantation of a constrained liner.ConclusionsA compressive osseointegration endoprosthesis is an option for very difficult revisions or sarcoma resection in the upper extremity in which the remaining segment of host bone is too short for a conventional prosthesis. However, surgeons must inform patients that these are salvage operations, and revision surgery is common. Long-term followup of more patients is necessary to further document the survivorship of these implants in the upper extremity.Level of EvidenceLevel IV, therapeutic study.

Compressive Osseointegration Into a Custom Acetabular Implant Masquerading as Tumor Recurrence: A Case Report

BackgroundCompressive 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 DescriptionWe 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 ReviewThe 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 RelevanceWe found PET-CT useful to differentiate the midterm radiographic appearance of the remodeling produced by compressive implant osseointegration from local recurrence.

Mosaic-pattern dedifferentiation in liposarcoma and chondrosarcoma: imaging features of an uncommon form of dedifferentiation

The term “dedifferentiation” was classically used in sarcoma pathology to refer to tumors in which a high-grade, undifferentiated sarcoma, or a high-grade sarcoma showing heterologous differentiation, arises from a pre-existing neoplasm of borderline or low-grade malignancy. The best recognized examples of this include dedifferentiated liposarcoma, arising from atypical lipomatous tumor/well-differentiated liposarcoma, and dedifferentiated chondrosarcoma, arising from grade 1 hyaline chondrosarcoma of bone. In the overwhelming majority of cases, this dedifferentiated, high-grade sarcoma presents as a macroscopically visible mass, adjacent to and clearly distinct from the pre-existing low-grade lesion. It is less well appreciated that dedifferentiation may also occur in a so-called “mosaic pattern,’ in which the high-grade component is intimately admixed with elements of the precursor lesion, forming only microscopically apparent foci. This mosaic or co-mingling pattern of dedifferentiation is also reflected in the MR imaging appearance. In contrast to the classic pattern of dedifferentiation in which there are two distinct juxtaposed masses with different signal intensities and enhancement patterns, such changes are not seen in mosaic dedifferentiation. The imaging features of this pattern of dedifferentiation have not been described. In this report we describe the imaging features of two patients with mosaic pattern dedifferentiation, one with liposarcoma and one with chondrosarcoma. In both cases the precursor lesion was correctly diagnosed by pre-biopsy imaging, but the presence of high-grade sarcoma was not recognized.

Evidence of Pent-Up Demand for Total Hip and Total Knee Arthroplasty at Age 65

BACKGROUND Despite efforts to curtail the economic burden of total joint arthroplasty (TJA), utilization of these successful procedures continues to increase. Previous studies have provided evidence for pent-up demand (delaying necessary medical care until financially feasible) in health care as insurance status changes. We sought to determine whether evidence exists for pent-up demand in the TJA population when patients become eligible for Medicare enrollment. METHODS The 2014 Nationwide Readmission Database was used to determine the incidence of TJA. The observed increase in incidence from age 64 to 65 was compared to the expected increase. Pent-up demand was calculated by subtracting the expected from the observed difference in frequency of TJA, and excess cost was determined by multiplying this value by the median cost of a primary TJA. The Medicare Expenditure Panel Survey Household Component was used to compare out-of-pocket (OOP) costs, access to care, and insurance coverage among patients aged 60-64 (group 1) and 66-70 (group 2). RESULTS The expected and observed increases in TJA procedures from age 64 to 65 were 595 and 5211, respectively, resulting in pent-up demand of 4616 joint arthroplasties (1273 THA and 3343 TKA), and an excess cost of

Erratum to: Use of Compressive Osseointegration Endoprostheses for Massive Bone Loss From Tumor and Failed Arthroplasty: A Viable Option in the Upper Extremity

55 million (range,