Introduction

In recent years, many studies demonstrated the efficacy of an early switch to oral antibiotics after surgical treatment in orthopaedic related infections. However, large analyses on periprosthetic joint infections (PJIs) are lacking.

Aim

This study aimed to externally validate promising preoperative PJI prediction models in a recent, multinational European cohort.

Aim

Debridement, antibiotics, and implant retention (DAIR) is a viable treatment option for acute periprosthetic joint infections (PJI). The landmark DATIPO trial of Bernard et al. concluded that six weeks is not non-inferior to 12-week antibiotic therapy for DAIR. However, it is unknown if suppressive antibiotic treatment (SAT) would improve patient outcomes. Therefore, our study aims to evaluate the utility of SAT after 12 weeks of therapy.

Background

The duration and extent of postoperative wound leakage after joint arthroplasty in patients with or without a complicated course, like a prosthetic joint infection (PJI), is currently unknown. Adequate differentiation between normal postoperative wound leakage and wound leakage due to a postoperative PJI is important and prevents unnecessary surgical procedures. We investigated the association between postoperative wound leakage and development of PJI in patients who used a previously developed mobile wound care app.

Aim

Low-grade infections are difficult to diagnose. As the presence of a chronic infection requires extensive surgical debridement and antibiotic treatment, it is important to diagnose a SII prior to surgery, especially when the hardware is revised. We investigated whether serum inflammatory markers or nuclear imaging can accurately diagnose a chronic spinal instrumentation infection (SII) prior to surgery.

Aim

Rifampin is considered as the antibiotic corner stone in the treatment of acute staphylococcal periprosthetic joint infections (PJI). However, if, when, and how to use rifampin has been questioned. We evaluated the outcome of patients treated with and without rifampin, and analysed the influence of timing, dose and co-antibiotic.

Aim

Treatment success of debridement, antibiotics and implant retention (DAIR) is in early periprosthetic joint infection (PJI) is largely dependent on the presence or absence of a mature biofilm. In what time interval a mature biofilm develops is still unclear, and therefore, the time point at which DAIR should be disrecommended remains to be established. This large multicenter trial evaluated the failure rates of DAIR for different time intervals from index arthroplasty to DAIR in early PJI.

Aim

Obese patients are not only more likely to receive total joint arthroplasty, but are also more prone to postoperative complications. The most severe complication is a prosthetic joint infection (PJI), occurring two to four times more often in severely obese patients (BMI ≥ 35kg/m²) compared to non-obese patients. This higher risk for PJI may be attributed to higher glucose levels in case of diabetes mellitus, diminished wound healing or inadequate antibiotic prophylaxis. To ultimately improve the prevention measures for this specific patient category, we aimed to describe the clinical and microbiological characteristics of early acute PJI in severely obese patients.

Aim

White blood cell (WBC) scintigraphy for diagnosing fracture-related infections (FRIs) has only been investigated in small patient series. Aims of this study were (1) to establish the accuracy of WBC scintigraphy for diagnosing FRIs, and (2) to investigate whether the duration of the time interval between surgery and WBC scintigraphy influences its accuracy.

Aim

Diagnosing or excluding a chronic prosthetic joint infection (PJI) prior to revision surgery can be a clinical challenge. To enhance accuracy of diagnosis, several biomarkers were introduced in recent years, but most are either expensive or not available as a rapid test. We compared the diagnostic accuracy of leucocyte esterase (€0.20 per sample), calprotectin (€20 per sample) and alpha defensin (€200 per sample).

Computer Assisted Surgery (CAS) and Patient Specific Instrumentation (PSI) have been reported to increase accuracy and predictability of tumour resections. The technically demanding joint-preserving surgery that retains the native joint with the better function may benefit from the new techniques. This cadaver study is to investigate the surgical accuracy of CAS and PSI in joint-preserving surgery of knee joint.

CT scans of four cadavers were performed and imported into an engineering software (MIMICS, Materialise) for the 3D surgical planning of simulated, multiplanar joint-preserving resections for distal femur or proximal tibia metaphyseal bone sarcoma. The planned resections were transferred to the navigation system (OrthoMap 3D, Stryker) for navigation planning and used for the design and fabrication of the PSI. Each of the four techniques (freehand, CAS, PSI and CAS + PSI) was used in four joint-preserving resections. Location accuracy (the maximum deviation of distance between the planned and the achieved resections) and bone resection time were measured. The results were compared by using t-test (statistically significant if P< 0.05).

Both the CAS+PSI and PSI techniques could reproduce the planned resections with a mean location accuracy of < 2 mm, compared to 3.6 mm for CAS assistance and 9.2 mm for the freehand technique. There was no statistical difference in location accuracy between the CAS+PSI and the PSI techniques (p=0.92) but a significant difference between the CAS technique and the CAS+PSI (p=0.042) or PSI technique (p=0.034) and the freehand technique with the other assisted techniques. The PSI technique took the lowest mean time of 4.78 ±0.97min for bone resections. This was significantly different from the CAS+PSI technique (mean 12.78 min; p < 0.001) and the CAS technique (mean 16.97 min; p = < 0.001).

CAS and PSI assisted techniques help reproduce the planned multiplanar resections. The PSI technique could achieve the most accurate bone resections (within 2mm error) with the least time for bone resections. Combining CAS with PSI might not improve surgical accuracy and might increase bone resection time. However, PSI placement on the bone surface depends only on the subjective feeling of surgeons and may not apply if the extraosseous tumor component is large. Combining CAS with PSI could address the limitations.

Introduction

In the last couple of years, several synovial biomarkers have been introduced in the diagnostic algorithm for a prosthetic joint infection (PJI). Alpha defensin-1 proved to be one of the most promising, with a high sensitivity and specificity. However, a major disadvantage of this biomarker is the high costs. Calprotectin is a protein that is present in the cytoplasm of neutrophils, and is released upon neutrophil activation. Its value has been established for decades as a (fecal) marker for inflammatory bowel disease.

Most types of bone tumor surgery require intra-operative imaging or measurement to control margins and prevent unnecessary bone loss. Computer Assisted Surgery (CAS) has been used as a replacement of fluoroscopy or direct measurement tools in four specific types of oncological orthopaedic surgical approaches. There are intralesional treatments, image-based resections, image-based resections with image-based reconstructions and image-based resections with imageless tumor prostheses reconstruction. Since 2006 we have performed 130 oncological surgeries with CAS.

Most cases were excochleations, 64, where CAS replaces fluoroscopy as an intra-operative imaging modality. Advantages over fluoroscopy are real time three dimensional feedback, high-res image and no use of ionizing radiation. It is especially useful in larger lesions or lesions located in the femoral head or pelvis. Currently a study is being performed on patient satisfaction, recurrence and complications.

Another application where CAS has often been used is in resections and segmental resections (together 45). These can be preplanned before surgery, incorporating the margin required, and checked intra-operatively. Coloration of the tumor, critical structures is useful to avoid these. Sometimes it's possible with careful planning to spare structures that otherwise probably would not confidently have spared.

With hemicortical resection (5) it's possible to use CAS to exactly copy the shape of the resected bone to an allograft. A Ct scan of one case shows an average gap between host and graft of 0.9 mm (range 0–5.4) along the 6 cm resection.

Finally in 16 cases of imageless use in placement of tumor prostheses it feels greatly helpful in reconstructing the joint line, length and correct rotation.

There were 8 failures in these 130 cases with the system or software. Setup time was measured in 47 cases and was on average 6:50 (range 2:26–14:27). Indication and performance of CAS in orthopedic oncology is an under researched aspect of CAS. In our opinion CAS shows great promise in the field of orthopedic oncology and is a valuable tool in the operating room.

Adamantinoma are rare, low grade malignant, bone tumors, making up only 0.1–0.48 percent of primary malignant bone tumors. They occur predominantly in the long bones, especially the tibia. Histogenetically it is thought that it originates from embryological displacement of basal epithelium of the skin, although other hypotheses have been proposed. Clinically most patients present with swelling and possible bending of the tibia, painful or painless. It's often noticed in an earlier stadium, but symptoms are non-specific and have a slow progressive character. Median patient age is 25 to 35 years, with a range from two to 86 years. It is slightly more common in men than woman, with a ratio of 5:4. Occurrence in children is even rarer. A study by Van Rijn et al. finds only 119 references, and presents six more cases. Treatment is the same. An MRI-scan should be performed to check for metastasis, loco regional staging and for operative planning. Operative excision and reconstruction is necessary to prevent metastasis and maintain load bearing capacity.

Generally these resections and reconstructions are done without objective measurements. The surgeon uses a rule of thumb, like a sculptor, or ruler approach to recreate the excised bone, either with allo- or autograft materials. An optimal fit, i.e. a minimal space between tibia and graft, is not always achieved, possibly resulting in pathological fractures.

This risk of pathological fractures lengthens recovery time. The fractures elongate hospitalization time and recovery time and are a heavy burden to patients. Computer assisted surgery (CAS) systems, used for example in prosthesis placement, offer objective measurements in 3d space of hard structures with high accuracy. These can be used to produce an accurate copy of the resected bone. If the reconstruction accurately fits the bone defect that's left after the resection, it's likely that the occurrence of pathological fractures decreases.

An adamantinoma in the tibia of a 12 year old boy was treated. Surgery consisted of hemicortical resection and inlay allograft reconstruction. The software used was the Orthomap navigation software (Stryker). A donor bone was supplied with help from the bone bank. The technical approach to the reconstruction was the planning of resection planes around the tumor. As the CT scale for both the patient and allograft bone is the same, the resection planes in the patient navigation setup could be copied to the allograft creation setup. Normal CAS setup was performed after first incision, with a tracker attached to the tibia. It was planned that a navigated bone saw would be used for the cutting. The tracker was attached to the saw with a new attachment, and calibrated in the universal calibration tool. During the surgery the oscillating saw proved to be impossible to navigate. The instrument calibration module was not able to accurately registered the saw, this despite accurate registrations in pre-operative testing. The CAS system was used however for accurately determining the saw planes. The planes were traced with the pointer tool. Then a non-navigated saw was used to perform both trapezoid shaped resections. A similar CAS setup was performed on the donor bone.

The reconstruction was a good fit. The skin was closed in layers. Post-operative x-ray control was performed. Operation time was just over two hours. Currently the follow-up time is five months. There have been no complications and the control x-rays show good allograft ingrowth.

While the original operation plan couldn't be performed the principle of computer assisted reconstruction has its merits. This was a proof of concept. The navigation was accurate to less than 1 mm, and the trapezoid resection shape guarantees a good fit. However the method of resection of the drawn planes by non-navigated bone saw was not accurate enough, because of the saw oscillations. There was improvement in operation time. With more accurate means of resection, as for example a computer controlled laser or water-jet, this type of reconstruction could have other very interesting applications.

Introduction: Infection is a challenging problem in orthopaedic surgery. In oncologic and revision surgery large prosthesis are placed during long procedures, even in patients with immunocompromised status. Infection rates here are reported up to 10%. Infections may necessitate large segmental resections thereby creating large defects. This defect can be filled with antibiotics loaded beads that release the substances locally to sterilise the defect. In recent years solid antibiotic loaded bone cement spacers have been applied. These spacers fill the defect, stabilize the extremity, release antibiotics and keep the soft tissues on their original length. Additionally, the patients will be able to preserve mobile function as well. In small defects prefabricated bone cement spacers temporarily replace the infected hip or knee prosthesis. For larger segmental of terminal defects there are no readily available constructs.

Purpose: To report short term outcome of a newly developed customized spacer concept for treatment of large segmental resections after prosthetic infection or osteomyelitis.

Material and Methods: We have treated 13 patients with large segmental defects after infection treatment with customized antibiotic bone cement spacers reinforced with strong intra-medullar implants like the Gammanail, the DFN and the UHN.

Results: These customized spacers are easy to make, fill the defect, stabilize the extremity, release antibiotics, keep the length of the soft tissues and allow patients to practice and preserve joint function as well. In 11 of 13 patients operated with an interim construct like this, a successful reimplantation of a tumor prosthesis was performed.

Conclusion: With customized antibiotic bone cement spacers augmented with a solid implant one can fill the defect, stabilize the extremity, release antibiotics and keep the soft tissues on their original length and keep function as well in infected tumorprosthesis. Successful reimplantation could be performed in 11 of 13 cases.

In oncological resections there is a higher risk of infection around the foot and ankle. An infection here can be difficult to treat and easily lead to an amputation due to the limited amount of soft tissue coverage of the region. In three patients an infection developed after resection of a bone tumour in the foot and ankle.

In the first case, female 34 years, an epitheloid hemangioepithelioma was excised from the anterior part of the calcaneus, cuboid and lateral os cuneiform. An iliac crest graft was initially used to fill the defect, but got infected. The antibiotic loaded bone cement spacer cured the infection and filled the dead space but was painful. A free vascularised fibula with skin-flap was used successfully to fill the defect and take away the pain. At three-year follow-up there is no pain and full weight bearing, with a nice hypertrophy of the graft. In the second case, a 14-year old girl, there was an Aneu-rismal Bone Cyst (ABC) of the distal tibia with a deep infection after ethibloc injection. The vacuum assisted closure cleaned the wound but a defect resulted. It was successfully filled with an ipsilateral free vascularised fibula with skin-flap. Follow-up shows full function and nice hypertrophy at 24 months. In the third case, male 65 years, a chondrosarcoma grade one (after biopsy) in the cuboid was curetted out. It proved grade two in the definitive histology and furthermore it got infected. The cuboid was excised and a cement spacer was placed. The soft tissues were insufficient to close it properly. A free vascularised fibula with skin-flap was used. The vascularity of the graft was insufficient and the skin-flap did not survive. A vacuum assisted closure was done. He can bear weight and has no pain. The fibula graft is shows some hypertrophy and a fistula persists for 18 months now.

We conclude that vascularised free fibula with skinflap can successfully prevent amputation in case of infection in oncological resection of foot and ankle. The fibula reconstructs the bone defect and the skin-flap the soft tissue defect.

Enchondromatosis is a non-hereditary disease, characterised by the presence of multiple enchondromas. While Ollier Disease is typified by multiple enchondromas, in Maffucci Syndrome they are combined with haemangioma.

Due to the rarity of these diseases, systematic studies on clinical behaviour providing information how to treat patients are lacking.

This study intends to answer the following questions: What are predictive factors for developing chondrosarcoma? When is extensive surgery necessary? How often patients die due to dedifferentiation or metastasis?

Twelve institutes in eight countries participated in this descriptive retrospective EMSOS-study. 118 Patients with Ollier Disease and 15 patients with Maffucci Syndrome were included. Unilateral localization of disease was found in 60% of Ollier patients and 40% of patients with Maffucci Syndrome.

One of the predictive factors for developing chondrosarcoma is the location of the enchondromas; the risk increases especially when enchondromas are located in the scapula (33%), humerus (18%), pelvis (26%) or femur (15%). For the phalanges, this risk is 14% in the hand and 16% in the feet. The decision whether or not to perform extensive surgery is difficult, especially in patients who suffer multiple chondrosarcomas.

Malignant transformation was found in fourty-four patients with Ollier Disease (37%) and eight patients with Maffucci Syndrome (53%). Multiple synchronous or metachronous chondrosarcomas were found in 15 patients.

Nine patients died (range 21–54 yrs). Seven of them died disease related due to pulmonary metastasis (2 humerus, 2 pelvis, 3 femur). Two patients died from glioma of the brain.

In conclusion, one important predictive factor for developing chondrosarcoma is the location of the enchondromas; interestingly, only patients with chondrosarcoma outside the small bones died of their disease. In this series, no dedifferentiation of chondrosarcoma was seen. A first design flow-chart how to approach chondrosarcoma in patients with Ollier Disease and Maffucci Syndrome is in preparation.

Bone tumours around the foot are relatively rare. I composed a poster with a short history and some images on seven different tumours around the foot. The reader is asked to give the most likely diagnosis. The answers can be found hidden on the poster.

The aim is to enlarge the knowledge of the EMSOS participants on tumours around the foot.

Radio Frequency Ablation (RFA) is a precise CT-guided technique to generate a small pre-defined field of dissecated tissue. Its’ present use in orthopaedic oncology is to treat osteoid osteoma. We have also treated other lesions with RFA and want to report our present indications and complications.

From 2005 to 2008 we performed 30 procedures: 23 osteoid osteomas, five low-grade chondrosarcomas, one chondroblastoma and one thyroid metastasis. Localisations were femur in 14 cases, tibia in 10, calcaneus in two, fibula in two, sacrum in one and scapula in one. All patients were treated with CT- guided RFA (Boston Scientific).

Follow-up for osteoid osteoma was done without additional imaging, all patients but one were pain free within 2 weeks; this one patient proved to have a chronic osteomyelitis although we thought we saw a nidus on CT. In one patient a burn wound complicated treatment because of unnoticed damage of the isolation layer of the probe. A free skin graft was necessary. We performed MRI controls and curettages for the chondrosarcomas in three patients, in one patient a fracture developed in the calcar femoris region after three months and a hip replacement was done. The patient with chondroblastoma is followed by MRI and there is no activity on contrast MRI two years after the procedure. In one lady a RFA was done for thyroid metastasis in the calcar femoris region. She fractured her collum femoris and got a hip replacement. In all tissue retrieved after RFA (curettage and hip replacement), there was complete necrosis of the tumour (chondrosarcoma grade one and thyroid metastasis).

RFA is an effective procedure for osteoid osteoma. Fracture and skin burns can occur. It is promising in low-grade chondrosarcoma and chondroblastoma. A study has been initiated recently to evaluate effectiveness of RFA in low-grade chondrosarcoma < 4 cm.

In orthopaedic oncology surgical precision is important and intraoperative imaging is often necessary. CAS may enhance precision and provide continuous 3D imaging without radiation. The goal of this work is to report our experience with CAS.

Since 2006 we used CAS (Stryker) in 26 patients with a bone tumour: 11 chondrosarcomas, three osteosarcomas, seven osteochondromas and five miscellaneous. Twelve lesions were located in the femur, six in the pelvis, five in the lower leg and three in the upper extremity. In 18 cases a tumour was excised, in six of these a prosthesis was placed. In eight cases a curettage was done. In 23 cases the navigation was image-based (CT and/or MRI based) and in three cases image-less (no image-preparation necessary preoperatively).

CAS was successfully employed in 23 cases. In three cases the procedure was aborted. In two cases, both in the ulna, we were unable to reconstruct the exact dimensions and in one case (image-less) the tracker was to far away from the work-field. There were no complications related to CAS. Mean precision is 0.5 mm. The time CAS takes is about 15 minutes during the procedure (7–60). In the eight curettages it proved helpful. We did not measure radiation time. In the six resections were tumour-prostheses were placed it was really helpful in rotation and length determination. In three of these, image-less navigation was performed (all distal femur). In osteochondroma resections it is helpful in four of seven cases. All surgical margins were adequate in the resections; after curettage, all MRI controls at three months did not show residual tumour. Oncology follow-up is too short yet; there was one local recurrence after two years in a parosteal osteosarcoma.

We conclude that CAS can be our navigator in orthopaedic oncology; it is successful in providing precision and continuous 3D imaging. The indication area needs further study.