Errors and pitfalls in the diagnosis and treatment of metastatic bone disease.

1. The orthopedist must be sure of the diagnosis and not embark on treatment for the wrong diagnosis. 2. Solitary lesions in patients with a remote history of malignancy require complete investigation and biopsy. This includes blood work, bone scan, magnetic resonance imaging of the bone lesion, and CT scan of the chest and abdomen. 3. Pathologic fractures do not require immediate fixation. They require careful surgical planning and a team approach to the underlying malignancy. 4. Load-sparing devices should not be used. 5. Femoral neck fractures should be treated by endoprosthetic replacement, and consideration should be given to long-stemmed femoral components. 6. The orthopedist should assume that the fracture will never heal. 7. Immediate full and unrestricted weight bearing should be planned. 8. Future problems in the surgical site should be anticipated. Often a long-stem cemented femoral component is a better choice than a standard length. 9. The orthopedist must ensure that there are no other lesions that require stabilization in the bone being treated. 10. Methyl methacrylate can be used to augment fixation if needed. 11. If secure fixation cannot be achieved with the use of cement, the bone should be replaced with a tumor endoprosthesis. 12. The orthopedist should not hesitate to call in help. These can be difficult situations to manage and often require the assistance of a tumor surgeon and oncologic team.

The PROSTALAC functional spacer in two-stage revision for infected knee replacements. Prosthesis of antibiotic-loaded acrylic cement.

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.

MDR1 gene expression and outcome in osteosarcoma: a prospective, multicenter study.

PURPOSE: Increased expression of the multidrug resistance gene (MDR1) has been implicated in osteosarcoma prognosis. This study represents the first prospective assessment of the prognostic value of MDR1 mRNA expression in patients with newly diagnosed extremity osteosarcoma. PATIENTS AND METHODS: A series of patients with high-grade, nonmetastatic extremity osteosarcoma were enrolled from six tertiary care institutions and observed prospectively for tumor recurrence (median follow-up duration, 30 months). All patients were treated with (neo)adjuvant chemotherapy and surgery. Tumors from 123 patients were analyzed for MDR1 mRNA expression. The association of the level of MDR1 expression with the risk of systemic recurrence was examined using survival analyses with traditional and histologic markers as prognostic factors. RESULTS: Using the highest MDR1 value for each patient, a dose-response relationship was not identified between the level of MDR1 expression and systemic relapse (relative risk, 1.15; P =.44). Analyses based on biopsy or resection values alone gave similar results (P =.11 and.41, respectively, log rank test). In multivariate analysis, large tumor size (> 9 cm) was the only significant independent predictor of systemic outcome (relative risk, 2.8; P =.002). CONCLUSION: We did not identify any correlation between MDR1 mRNA expression and disease progression in patients with osteosarcoma. It is likely that alterations in other genes are involved in resistance to chemotherapy in osteosarcoma and that they play a more critical role than MDR1 in this disease.

The quadriceps myocutaneous flap for operation on the distal femur.

We describe a U-shaped approach to the distal femur which, having divided the extensor mechanism and elevated the entire quadriceps muscle, gives excellent exposure and allows a number of reconstructive options. It was used in 14 patients, 13 of whom were followed up for a mean of 3.5 years (1 to 11). There was no case of flap necrosis, and complications related to the reconstruction were acceptable.

Long-term elution of antibiotics from bone-cement: an in vivo study using the prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) system.

A prospective study of 49 patients undergoing a modified 2-stage exchange arthroplasty for infected total hip and knee arthroplasties using the prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) system with a variety of doses of tobramycin and vancomycin was performed. The intra-articular concentrations of tobramycin and vancomycin were measured at the time of removal of the PROSTALAC temporary spacer and reimplantation of a definitive joint arthroplasty prosthesis, at a mean 118 days following initial implantation. The 95% confidence interval of the intra-articular concentration of tobramycin (4.35-123.88 mg/L) was entirely above the breakpoint sensitivity limit for sensitive organisms when at least 3.6 g of tobramycin was used per package of bone-cement but was entirely below it when at most 2.4 g was used. Vancomycin elution was not as good; however, detectable levels were still present in most patients. There was a statistically significant increase in the elution of vancomycin when the dose of tobramycin was increased from at most 2.4 g to at least 3.6 g. The dose of vancomycin in the cement did not influence the elution of either tobramycin or vancomycin. On the basis of these results, the use of at least 3.6 g of tobramycin and 1 g of vancomycin per package of bone-cement is recommended when antibiotic-loaded cement spacers are used in 2-stage exchange arthroplasty for infected total hip and knee arthroplasties.

Bacterial growth on antibiotic-loaded acrylic cement. A prospective in vivo retrieval study.

Twenty-three patients with intraoperative culture-proven periprosthetic infection of the hip or knee were enrolled in a prospective cement retrieval study. All were treated with a two-stage technique using antibiotic-loaded acrylic cement as an antibiotic depot. Staphylococcus epidermidis was the most commonly isolated organism (19 of 23 cases). Cement and tissue were examined at second-stage revision for the presence of viable organisms. In this series, no organisms were isolated from the surface of the cement, a 100% concordance with the tissue cultures. A subsequent failure rate of 4.4% (1 case) was seen in this series. Investigation suggests this may represent reinfection from a new strain of organism rather than failure of eradication of the original infection.

Effect of varying surface patterns on antibiotic elution from antibiotic-loaded bone cement.

In an effort to improve the antibiotic elution characteristics of the prosthesis of antibiotic-loaded acrylic cement, an in vitro study was conducted. Tobramycin-loaded bone cement blocks of three different surface patterns with different surface area-to-volume ratios were used. The elution of tobramycin over a 2-month period was investigated. There was a gradual decline in the tobramycin elution rate over time. The surface pattern with the increased surface area-to-volume ratio showed a significant increase in the tobramycin elution rate over the first week of the study. The surface pattern with ridges but no change in the surface area-to-volume ratio did not result in a statistically significant increase in the tobramycin elution rate.

Solitary fibrous tumor of the periosteum.

We report a solitary fibrous tumor (SFT) of the leg that presented as a pedunculated encapsulated soft tissue mass attached to the periosteum of the posterior tibia. To our knowledge this is the first reported case of an SFT in an extremity. In addition to having the typical gross and microscopic appearance of a usual SFT, this SFT also contained abundant elastic tissue, suggesting an origin from periosteal fibroblasts. This report further extends the anatomic range of the SFT, a neoplasm once thought to be of mesothelial origin but now recognized as a mesenchymal tumor of probable fibroblastic lineage. To date the behavior of the this periosteal SFT has been benign.

Position of the knee joint after total joint arthroplasty.

A method for assessing knee joint position after surgery using the preoperative long-leg radiograph and the postoperative knee radiograph is described. Assessment of the formula has shown a near perfect correlation between the calculated position on the long-leg radiograph compared with the measured position for 44 knees. Three hundred eighteen knees after total joint arthroplasty were retrospectively reviewed and the postoperative position was determined. The preoperative position of the mechanical axis was 14.5 +/- 37.3 mm medial to the knee joint center. Using the standing knee radiograph the postoperative position of the mechanical axis was 3.07 +/- 9.2 mm lateral to the knee joint center, while the portable radiograph placed the mechanical axis 4.5 +/- 12.4 mm medial to the knee joint center. There was a highly significant difference in the position of the knee joint center depending on the radiograph used for calculation (standing or portable). The difference between the two means was not due to opening of the knee joint, but likely due to change in the rotation of the knee in the presence of knee flexion. This series of the knee arthroplasties has a low projected rate of aseptic failure.

Robotrac in total knee arthroplasty. The silent assistant.

This article describes a new prerobotic device (Robotrac) that may be used effectively in total knee arthroplasty (TKA). This device holds the femur in any position, allowing the surgeon to situate the knee in any position of flexion that may be necessary during the course of TKA. Using this device, it often is possible to perform TKA without any additional assistant surgeons. To date, we have used Robotrac in more than 200 consecutive total knee replacements without any untoward effects. With the use of this device, it is possible to save about $142 Canadian per total knee replacement. The literature concerning the use of robotics in medicine is reviewed.

Temporary antibiotic loaded acrylic hip replacement: a novel method for management of the infected THA.

Postoperative infection after hip joint replacement is an uncommon but potentially devastating complication in contemporary orthopaedics. Management in two stages is the more favored approach in North America. This introduces difficulty with patient management in the interval between stages, delays rehabilitation, and introduces technical difficulty during the second stage. A method has been developed whereby a temporary antibiotic-loaded facsimile of the hip is introduced at the first stage, designed to maintain stability of the joint, length of the limb, and mobility of the patient. It has been used in a total of 86 cases to date. The results in 46 cases with a minimum follow-up of 2 years are reviewed in this article. The infection was controlled in 93.5% of cases.

Two-stage exchange arthroplasty using a functional antibiotic-loaded spacer in the treatment of the infected knee replacement: the Vancouver experience.

Two-stage exchange arthroplasty is currently the method of choice in the treatment of the infected knee replacement. The prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) is a temporary, antibiotic-loaded functional prosthesis that is used as an interim spacer in two-stage exchange arthroplasty. In this prospective series, we report on the early results of the use of the PROSTALAC knee spacer in two-stage exchange arthroplasty of infected knees. A total of 24 knees were treated with this prosthesis, and were reviewed at a mean follow-up time of 2.2 years. Infection was controlled in all but 2 knees, for an infection cure rate of 91.7%. The patients' function was improved between stages, and motion was maintained in the majority of cases. The significant complications with the PROSTALAC implant in place were tibio-femoral instability, which was corrected with a design modification, and patellar instability, which continues to be a problem. These complications were transient and were not of any significance after the second stage.

Prevention of vascular injuries in revision total hip replacement.

Iliac-vessel injury from total hip arthroplasty is associated with hemorrhagic complications and an increased death rate. The authors identified seven patients who had severe medial displacement of the acetabular prosthesis and associated vascular injury to the iliac vessels after total hip replacement. One patient had two hip replacements. Preoperative findings included a pelvic mass (three hips), pelvic pain (eight), radiologic evidence of cement in the pelvis (three) and the acetabular prosthesis in the pelvis (eight), computed tomographic evidence of cement in the pelvis and proximity of the prosthesis to the iliac vessels (four), and arteriography showing displacement or compression of the iliac vessels (seven). Operative management in all cases involved medial exposure, mobilization and repair of the iliac vessels before revision of the hip prosthesis. Postoperative complications were deep vein thrombosis (three), in spite of prophylaxis, and occlusion of a vein interposition graft (one) requiring placement of a femoral crossover graft. There were no deaths, amputations or hemorrhagic complications. The authors advocate preoperative identification of patients who have iliac-vessel involvement by their total hip prosthesis and initial medial extraperitoneal exposure and repair of these vessels before removal of the displaced acetabular prosthesis.

Osteoblastoma: experience with 23 patients.

A retrospective review of 23 patients with osteoblastoma was undertaken in an attempt to answer questions concerning the aggressiveness and potential malignancy of this tumour. Demographic information confirmed that recorded in the literature. There was no suggestion of malignant potential, but, significantly, one tumour persisted, with local recurrence after 11 operations over a period of 27 years. A second tumour, a spinal lesion, occurred (still in a benign form) after a symptom-free period of 17 years. Recognition of aggressive features clinically, radiologically and histologically suggests the need for more aggressive surgical treatment, and late recurrence indicates the need for a more guarded prognosis and longer follow-up.

Aggressive osteoblastoma. A case previously reported as a recurrent osteoid osteoma.

We review the case of a 58-year-old man with a benign osteoblastic lesion. This originated in the base of the right second metacarpal and eventually involved several adjacent bones, persisting for at least 27 years despite 11 operations. It was originally reported in the literature as a recurrent osteoid osteoma, but we believe it is more properly diagnosed as an aggressive osteoblastoma, since the histological pattern did not change over the years. The lesion has remained locally aggressive with no evidence of malignant characteristics.

Perioperative chemotherapy for primary sarcoma of bone.

Preoperative chemotherapy for primary osteosarcoma has usually been accompanied by a prolonged delay between withdrawal before operation and resumption after. This is because animal studies showed impaired wound healing associated with perioperative chemotherapy. Clinical studies, however, have not shown this to be the case. The authors describe their experience in eight patients who had osteosarcoma and Ewing's sarcoma of the extremities and received one to three cycles of chemotherapy preoperatively. Chemotherapy consisted of Adriamycin, cis-platinum and vincristine. Definitive surgery on the primary tumour was done 1 to 4 days after the last dose. Amputation was performed on seven patients and tumour resection for limb salvage on one. No wound healing or infectious complications were encountered. The ensuing course of chemotherapy was not delayed by the surgical procedure. The authors conclude that it is feasible to combine neoadjuvant chemotherapy and early surgery in the management of high-grade primary bone sarcoma.