Christopher P. Beauchamp

The PROSTALAC functional spacer in two-stage revision for infected knee replacements

The PROSTALAC functional spacer is made of antibiotic-loaded acrylic cement but has a small metal-on-polythene articular surface. We have used it as an interim spacer in two-stage exchange arthroplasty for infected total knee replacement. PROSTALAC allows continuous rehabilitation between stages as it maintains good alignment and stability of the knee and a reasonable range of movement. It also helps to maintain the soft-tissue planes, which facilitates the second-stage procedure. We reviewed 45 consecutive patients, treated over a period of nine years. The mean follow-up was for 48 months (20 to 112). At final review, there was no evidence of infection in 41 patients (91%); only one had a recurrent infection with the same organism. There was improvement in the Hospital for Special Surgery knee score between stages and at final review. The range of movement was maintained between stages. Complications were primarily related to the extensor mechanism and stability of the knee between stages. Both of these problems decreased with refinement of the design of the implant. The rate of cure of the infection in our patients was similar to that using other methods. Movement of the knee does not appear to hinder control of infection.

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.

Reconstruction of musculoskeletal defects about the knee for tumor

One of the most challenging problems of limb salvage is a large tumor involving the knee joint. Since 1970, 79 patients, ranging in age from 14 to 74 years (mean, 27 years), have had reconstruction of the knee after en bloc resection of a primary bone tumor. Sixty-one patients had lesions involving the distal femur, with a mean resection length of 13.5 cm, and 18 patients had lesions involving the proximal tibia, with a mean resection length of 10.5 cm. Thirty-nine patients had malignant lesions, of which osteosarcomas predominated, and 40 patients had benign tumors, of which giant cell tumors were the most prevalent. Reconstruction was done with a custom total knee arthroplasty in 41 patients, a resection arthrodesis in 27, and an allograft in 11. The functional results were graded according to the rating system devised by the Musculoskeletal Tumor Society. of the patients with resection arthroplasty, 70% had a good or excellent rating, although ten required revision. Of the patients with resection arthrodesis, 74% had a good or excellent rating, as did 55% of the patients with osteochondral allografts. When a limb salvage procedure is done, careful consideration must be given to the type of procedure chosen to reconstruct the knee. This decision is based on a number of factors related to the tumor and the patient. Although these various procedures promise functional restoration, the reconstructive procedure should be individualized and designed to meet the needs of the patient.

Chronic expanding hematoma of the thigh simulating neoplasm on gadolinium-enhanced MRI

Patients who present with slowly growing extremity masses are often imaged with MRI to be examined for possible tumors. In addition to cysts and neoplasms, chronic expanding hematomas should be considered in the differential diagnosis if the patient has a history of remote trauma. The presence or absence of internal contrast enhancement is often used to distinguish between hematomas and hemorrhagic neoplasms on MRI and CT. We present the unusual case of a patient who had a chronic expanding hematoma of the calf that demonstrated nodular internal enhancement on gadolinium-enhanced MRI, simulating a neoplasm.

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.

Five cases of failure of the tibial polyethylene insert locking mechanism in one design of constrained knee arthroplasty.

We describe 5 cases of failure of the locking mechanism of the polyethylene insert and tibial base-plate in one design of constrained condylar knee prosthesis due to disengagement of the locking screw. Loosening of the screw is believed to occur because of a counterclockwise torque created by the axial rotation of the femur on the tibia that occurs as the knee extends during gait. This torque is transmitted via the highly rotationally constrained femoral housing and tibial post to the locking screw. These failures suggest that an alternative locking mechanism should be considered for this prosthesis.

Functional free latissimus dorsi muscle flap to the proximal lower extremity.

Surgical treatment of lower extremity sarcoma often requires complete resection of muscle compartments resulting in disabling functional loss. Free muscle transfer has been used to restore function of the face and upper extremities, but few reports exist describing functional restoration of a lower extremity. A case report of a 21-year-old man requiring complete resection of the quadriceps musculature with successful functional reconstruction using a free latissimus dorsi muscle flap is described.

Integration of radiation oncology with surgery as combined-modality treatment.

Integration of surgery and radiation (external beam, EBRT; intraoperative, IORT) has become more routine for patients with locally advanced primary cancers and those with local-regional relapse. This article discusses patient selection and treatment from a more general perspective, followed by a discussion of patient selection and treatment factors in select disease sites (pancreas cancer, colorectal cancer, retroperitoneal soft-tissue sarcomas). Outcomes with combined modality treatment (surgery, EBRT alone or with concurrent chemotherapy, IORT) are discussed. The ultimate in contemporary integration of radiation and surgery is found in patients who are candidates for surgery plus both EBRT and IORT.

Case Report: Reconstruction of the Distal Tibia with Porous Tantalum Spacer after Resection for Giant Cell Tumor

Treatment options for giant cell tumors of the distal tibia include curettage and cement packing, curettage and bone grafting, or resection and reconstruction for aggressive tumors. Curettage of aggressive tumors often leads to severe bone loss requiring reconstruction. Allograft and autograft may be effective options for reconstruction, but each is associated with drawbacks including the possibility of infection and collapse. We present a case of giant cell tumor of the distal tibia treated with curettage and arthrodesis using a porous tantalum spacer. Complete removal of the tumor and successful arthrodesis of the ankle were accomplished using the spacer. The patient returned to pain-free walking along with eradication of the giant cell tumor. We believe porous tantalum spacers are a reasonable option for reconstructing the distal tibia after curettage of a giant cell tumor with extensive bone loss.

Extremity and Trunk Soft Tissue Sarcomas

Management of soft-tissue sarcomas of the extremities and trunk is optimally accomplished through a multidisciplinary team evaluation of each patient because of the diverse and complex nature of each clinical scenario. A team of orthopedic or surgical oncologists, radiation oncologists, medical oncologists, plastic surgeons, pathologists, and radiologists consider multiple issues including tumor stage, grade, location, and histologic type of tumor, as well as feasibility of a limb-sparing surgery, timing of radiation, and the patient’s performance status and comorbid illnesses. The rarity of these tumors in combination with the variety of presentation in extremity and truncal soft-tissue sarcomas limits the amount of prospective data available to reliably outline the management of all situations, and hence, there is a range of approaches utilized around the world today.