Aim

Synovial calprotectin point-of-care test (POC) has shown promising clinical value in diagnosing periprosthetic joint infections (PJIs). However, limited data are available in unclear cases. Moreover, cut-off values for calprotectin lateral flow assay (LFA) and enzyme-linked immunosorbent assay (ELISA) need to be adapted. The aim of this study was to evaluate the performance of an upgraded and more sensitive version of a synovial calprotectin LFA along with ELISA immunoassay in patients with septic, aseptic, and unclear cases.

Introduction

To evaluate the clinical success and hip pain and function of patients with infected hip replacement treated by two-stage exchange using a temporary implant with high dose vancomycin added to the antibiotic cement at the first stage revision.

Introduction

End-stage ankle osteoarthritis is a debilitating condition that results in functional limitations and a poor quality of life. Ankle arthrodesis (AAD) and total ankle replacement (TAR) are the major surgical treatment options for ankle arthritis. The purpose of the present study was to compare preoperative and postoperative participation in sports and recreational activities, assesses levels of habitual physical activity, functional outcome and satisfaction of patients who underwent eighter AAD or TAR.

Background: Endoprosthetic reconstruction has become the gold standard of treatment after the resection of tumors around the proximal femur, however, the rate of complications linked to megaprostheses is clearly higher than with standard implants. Aim of this study was to investigate the incidence and type of complications related to modular proximal femur prostheses.

Patients and Methods: By retrospective database analysis of the Vienna Tumor Registry, we evaluated the incidence of complications in 170 consecutive patients who have received a proximal femur KMFTR/GMRS at our institution between 1982 and 2007. 71 patients with an average age of 41.7 years (range 18.2–79.9 years) received the implant following the resection of a malignant bone tumor, 95 patients with an average age of 61.7 years (range 5.9–84.2 years) due to metastatic disease. The average time of follow-up was 3.5 years (SD ±4.9 years).

Results: Overall patient survival at five years was 32%. For patients with metastatic disease the overall survival was 10% at five years. Patients being treated for a primary bone tumor had an overall survival of 55% at 5 years. The overall survival of the prosthesis was 90% at two years and 72% at five years. Twenty-one patients (12.65%) suffered from dislocation after a mean time of 6.5 month (range 0.3–33 months) after surgery. Out of these, nine had to be treated by open reduction. Nine patients suffered recurrent dislocation after their first event. Patients who underwent extensive pelvic reconstruction had a significantly higher dislocation rate (33.3%) compared to patients with no or standard acetabular components (11.2%). Deep infection occurred in twelve patients (7.3%) after a mean of 39 months (range 1–166 months) after surgery. Treatment of infection was one-stage revision in eight and hip disarticulation in one patient. Two patients were successfully treated by local wound revision. One patient died of septic shock four days after surgery. Re-infection occurred in three patients. Aseptic loosing occurred in 13 patients (12.8%) after a mean time of 75.6 months (range 1–223 months) after surgery. Revision surgery was necessary in 27 patients (15.8%) with a mean time to first revision of 32 months (range 0.3–116 months). Prosthetic fracture was found in two patients. Local recurrence occurred in 14 patients (8.4%). In seven patients (4.2%) amputation was necessary.

Conclusion: Modular endoprosthesis allow excellent reconstruction of the proximal femur following tumor resection. However, the main complications, dislocation and infection, still remain considerable drawbacks.

The treatment of deep prosthetic infection in cancer patients with tumour prostheses remains the major complication to be dealt with in this population.

The Vienna Bone Tumour Registry includes information of more than 6500 patients of a period of 36 years. 145 patients with malignant proximal femoral tumors had resection and limb salvage with an uncemented Kotz modular femoral and tibial reconstruction megaprosthesis (KMFTR). There were twenty osteosarcomas, thirteen Ewing’s sarcomas, six chondrosarcomas, six plasmozytomas, three fibrosarcomas, three liposacomas and others. Thirteen patients (7 males, 6 females with an average age of 45 years, range 10 to 75 years) suffered from deep prosthetic infection within an average of 44 months after primary implantation, representing an infection rate of 8,97 percent.

Average follow-up was 109 months, range 7 to 339 months. Two patients with only mild signs of infection were treated by a conservative antibiotic regimen. Nine patients were treated by one-stage revision. One of the remaining two patients with severe infection underwent exarticulation of the hip as primary intervention, the other patient died due to general sepsis on the fourth post-operative day. Six patients showed no further signs of infection. Six patients, however, required one or more reoperations due to recurrent prosthetic infection. Among these four patients have successfully been treated by repeated one-stage revision, in two patients the prosthesis had to be removed permanently.

Deep prosthetic infection around modular tumour prostheses of the proximal femur and hip seems to be less common compared to distal femur, knee or tibia. However, the treatment of this complication has a higher failure rate due to multiply recurrent infection.

Background: Traditionally, it is believed that structural failure of the ischemic epiphysis as well as changes in radiodensity seen in Legg-Calve-Perthes disease are due to repair. Little is known if bone material properties are altered following ischemic necrosis of the juvenile femoral head. Purpose of this study was to determine bone matrix mineralization density, an important determinant of bone quality and strength, in an experimental model of juvenile ischemic osteonecrosis.

Methods: Ten piglets were surgically induced with ischemic osteonecrosis and euthanized at 4- and 8 weeks following surgery. Contralateral, unoperated femoral heads were used as controls. Bone Mineralization Density Distribution (BMDD) parameters were determined using quanitative backscattered electron imaging (qBEI) in the epiphyseal calcified cartilage, subchondral and central trabecular bone region. Histological assessment was also performed.

Results: In necrotic calcified epiphyseal cartilage matrix as well as subchondral bone matrix, a significant increase in the degree (CaMean, Ca Peak) as well as the homogeneity of mineralization (CaWidth reduction) and a significantly reduced amount of low mineralized matrix (CaLow) were observed at 4 and 8 weeks post ischemia induction. In the necrotic central trabecular region a significant increase in the degree and homogeneity of mineralization, as well as a decrease in the amount of low mineralized bone was found at 8 weeks post-ischemia induction, but not at 4-weeks, indicating that changes in necrotic trabecular bone occur more slowly. Changes in the necrotic calcified cartilage region were more dramatic than in necrotic bone.

Discussion: Our findings indicate that the mineralization process continues in the necrotic calcified cartilage and bone following femoral head infarction. This leads to an increased degree and homogeneity of mineralization in calcified cartilage and bone matrices and therefore altered material properties. These alterations in matrix mineralization status would lead to more brittle bone, prone to micro-fractures and may partly explain the weakening of structural properties of necrotic bone. Moreover, an increase in calcified cartilage and bone mineralization may also explain the increased radiodensity seen in the early stage of Perthes disease prior to repair and/or structural failure.

Introduction: Little data are available about the incidence and the management of hip dislocation following the implantation of megaprosthesis of the proximal femur, which is one of the main complications following this procedure.

Material and Methods: 190 patients, who received a proximal femur KMFTR/GMRS at our institution between 1982 and 2007, were retrospectively reviewed with regard to the incidence of hip dislocation as well as the success rate of the subsequent surgical/non-surgical treatment. A proximal femur tumor endoprosthesis was used in 148 patients following the resection of a malignant tumor and in 43 patients in severe revision cases following total hip arthroplasty. The average age at the time of surgery was 48 [6a to 83a] in the tumor group and 57.3 [45a to 78a] in the revision group. All of the revision cases and 12 patients from the tumor group had additional revision cups, such as the Schoellner pedestal cup.

Results: 12.3 % (18/147) of the tumor patients and 13.9% (6/43) of the revision cases dislocated at least once. 66.7% (12/18) of the first dislocations from the tumor and 50 % (3/6) of the revision group were treated with closed reduction, the rest required surgery. All patients received an abduction cast for at least 8 weeks. 38% (7/18) of the dislocated hips of tumor group (4.8% [7/147] total) and 67% (4/6) of the revision group (9.3% [4/43] total) experienced a second dislocation. 57% (4/7) of the dislocations from the tumor and 100 % (4/4) of the revision group were treated with closed reduction. Three patients from the tumor group (2% [3/147] total) experienced a total of three dislocations and one patient four dislocations (< 1% [1/147] total). The first dislocation occurred in 88% of the cases within 5 months following surgery during activities of daily living. 82% of the second dislocations and all third dislocations occurred within 4 months of the previous dislocation. Interestingly, no significant difference was found in the rate of re-dislocation between surgical and non-surgical treatment in either group.

Discussion: Dislocation of a proximal femur tumor endoprosthesis is an early complication following surgery and continues to be a challenging condition to treat, especially in cases with extensive soft-tissue defects. Since 2000, a polyester ligament is successfully used in our institution as a reinforcement to reduce the risk of hip dislocation in proximal femur tumor endoprosthesis. Surgical and non-surgical methods to reduce the risk of hip dislocation are discussed.