Patient-specific instruments (PSI) and surgical-guiding templates are gaining popularity as a tool for enhancing surgical accuracy in the correction of oblique bone deformities Three-dimensional virtual surgical planning technology has advanced applications in the correction of deformities of long bones and enables the production of 3D stereolithographic models and PSI based upon a patient's specific deformity. We describe the implementation of this technology in young patients who required a corrective osteotomy for a complex three-plane (oblique plane) lower-limb deformity. Radiographs and computerized tomographic (CT) scans (0.5 mm slices) were obtained for each patient. The CT images were imported into post-processing software, and virtual 3D models were created by a segmentation process. Femoral and tibial models and cutting guides with locking points were designed according to the deformity correction plan as designed by the surgeon. The models were used for preoperative planning and as an intraoperative guide. All osteotomies were performed with the PSI secured in the planned position.Introduction
Materials and Methods
Accurate estimations of the risk of fracture due to metastatic bone disease in the femur is essential in order to avoid both under-treatment and over-treatment of patients with an impending pathological fracture. The purpose of the current retrospective in vivo study was to use CT-based finite element analyses (CTFEA) to identify a clear quantitative differentiating factor between patients who are at imminent risk of fracturing their femur and those who are not, and to identify the exact location of maximal weakness where the fracture is most likely to occur. Data were collected on 82 patients with femoral metastatic bone disease, 41 of whom did not undergo prophylactic fixation. A total of 15 had a pathological fracture within six months following the CT scan, and 26 were fracture-free during the five months following the scan. The Mirels score and strain fold ratio (SFR) based on CTFEA was computed for all patients. A SFR value of 1.48 was used as the threshold for a pathological fracture. The sensitivity, specificity, positive, and negative predicted values for Mirels score and SFR predictions were computed for nine patients who fractured and 24 who did not, as well as a comparison of areas under the receiver operating characteristic curves (AUC of the ROC curves).Aims
Methods
Intra-articular 90Yttrium (90Y) is an adjunct
to surgical treatment by synovectomy for patients with diffuse-type tenosynovial
giant-cell tumour (dtTGCT) of the knee, with variable success rates.
Clinical information is, however, sparse and its value remains unclear.
We investigated the long-term outcome of patients who underwent synovectomy
with and without adjuvant treatment with 90Yttrium. All patients with dtTGCT of the knee who underwent synovectomy
between 1991 and 2014 were included in the study. Group A patients
underwent synovectomy and an intra-articular injection of 90Yttrium
between six and eight weeks after surgery. Group B patients underwent
surgery alone.Aims
Patients and Methods
Clear operative oncological margins are the main target in malignant bone tumour resections. Novel techniques like patient specific instruments (PSIs) are becoming more popular in orthopaedic oncology surgeries and arthroplasty in general with studies suggesting improved accuracy and reduced operating time using PSIs compared to conventional techniques and computer assisted surgery. Improved accuracy would allow preservation of more natural bone of patients with smaller tumour margin. Novel low-cost technology improving accuracy of surgical cuts, would facilitate highly delicate surgeries such as Joint Preserving Surgery (JPS) that improves quality of life for patients by preserving the tibial plateau and muscle attachments around the knee whilst removing bone tumours with adequate tumour margins. There are no universal guidelines on PSI designs and there are no studies showing how specific design of PSIs would affect accuracy of the surgical cuts. We hypothesised if an increased depth of the cutting slot guide for sawblades on the PSI would improve accuracy of cuts. A pilot drybone experiment was set up, testing 3 different designs of a PSI with changing cutting slot depth, simulating removal of a tumour on the proximal tibia (figure 1) A handheld 3D scanner (Artec Spider, Luxembourg) was used to scan tibia drybones and Computer Aided Design (CAD) software was used to simulate osteosarcoma position and plan intentioned cuts (figure 1). PSI were designed accordingly to allow sufficient tumour. The only change for the 3 designs is the cutting slot depth (10mm, 15mm & 20mm). 7 orthopaedic surgeons were recruited to participate and perform JPS on the drybones using each design 2 times. Each fragment was then scanned with the 3D scanner and were then matched onto the reference tibia with customized software to calculate how each cut (inferior-superior-vertical) deviated from plan in millimetres and degrees (figure 3). In order to tackle PSI placement error, a dedicated 3D-printed mould was used.Introduction
Methods
Dislocation is a common complication after proximal and total femur prosthesis reconstruction for primary bone sarcoma patients. Expandable prosthesis in children puts an additional challenge due to the lengthening process. Hip stability is impaired due to multiple factors: Resection of the hip stabilizers as part of the sarcoma resection: forces acts on the hip during the lengthening; and mismatch of native growing acetabulum to the metal femoral head. Surgical solutions described in literature are various with reported low rates of success. Assess a novel 3D surgical planning technology by use of 3D models (computerized and physical), 3D planning, and Patient Specific Instruments (PSI) in supporting correction of young children suffering from hip instability after expandable prosthesis reconstruction following proximal femur resection. This innovative technology creates a new dimension of visualization and customization, and could improve understanding of this complex problem and facilitate the surgical decision making and procedure.Background
Objective
The aim of this project is to test the parameters of Patient Specific Instruments (PSIs) and measuring accuracy of surgical cuts using sawblades with different depths of PSI cutting guide slot. Clear operative oncological margins are the main target in malignant bone tumour resections. Novel techniques like patient specific instruments (PSIs) are becoming more popular in orthopaedic oncology surgeries and arthroplasty in general with studies suggesting improved accuracy and reduced operating time using PSIs compared to conventional techniques and computer assisted surgery. Improved accuracy would allow preservation of more natural bone of patients with smaller tumour margin. Novel low-cost technology improving accuracy of surgical cuts, would facilitate highly delicate surgeries such as Joint Preserving Surgery (JPS) that improves quality of life for patients by preserving the tibial plateau and muscle attachments around the knee whilst removing bone tumours with adequate tumour margins. There are no universal guidelines on PSI designs and there are no studies showing how specific design of PSIs would affect accuracy of the surgical cuts. We hypothesised if an increased depth of the cutting slot guide for sawblades on the PSI would improve accuracy of cuts. A pilot drybone experiment was set up, testing 3 different designs of a PSI with changing cutting slot depth, simulating removal of a tumour on the proximal tibia. A handheld 3D scanner (Artec Spider, Luxembourg) was used to scan tibia drybones and Computer Aided Design (CAD) software was used to simulate osteosarcoma position and plan intentioned cuts. PSI were designed accordingly to allow sufficient tumour. The only change for the 3 designs is the cutting slot depth (10mm, 15mm & 20mm). 7 orthopaedic surgeons were recruited to participate and perform JPS on the drybones using each design 2 times. Each fragment was then scanned with the 3D scanner and were then matched onto the reference tibia with customized software to calculate how each cut (inferior-superior-vertical) deviated from plan in millimetres and degrees. In order to tackle PSI placement error, a dedicated 3D-printed mould was used. Comparing actual cuts to planned cuts, changing the height of the cutting slot guide on the designed PSI did not deviate accuracy enough to interfere with a tumour resection margin set to maximum 10mm. We have obtained very accurate cuts with the mean deviations(error) for the 3 different designs were: [10mm slot: 0.76 ± 0.52mm, 2.37 ± 1.26°], [15 mm slot: 0.43 ± 0.40 mm, 1.89 ± 1.04°] and [20 mm: 0.74 ± 0.65 mm, 2.40 ± 1.78°] respectively, with no significant difference between mean error for each design overall, but the inferior cuts deviation in mm did show to be more precise with 15 mm cutting slot (p<0.05). Simulating a cut to resect an osteosarcoma, none of the proposed designs introduced error that would interfere with the tumour margin set. Though 15mm showed increased precision on only one parameter, we concluded that 10mm cutting slot would be sufficient for the accuracy needed for this specific surgical intervention. Future work would include comparing PSI slot depth with position of knee implants after arthroplasty, and how optimisation of other design parameters of PSIs can continue to improve accuracy of orthopaedic surgery and allow increase of bone and joint preservation.
Femoral component design is a key part of hip arthroplasty performance. We have previously reported that a hip resurfacing offered functional improved performance over a long stem. However resurfacing is not popular for many reasons, so there is a growing trend towards shorter femoral stems, which have the added benefit of ease of introduction through less invasive incisions. Concern is also developing about the impact of longer stems on lifetime risk of periprosthetic fracture, which should be reduced by the use of a shorter stem. For these reasons, we wanted to know whether a shorter stem offered any functional improvement over a conventional long stem. We surmised that longer stems in hip implants might stiffen the femoral shaft, altering the mechanical properties. From our database of over 800 patients who have been tested in the lab, we identified 95 patients with a hip replacement performed on only one side, with no other lower limb co-morbidities, and a control group: 19 with long stem implant, age 66 ± 14 (LONG) 40 with short stem implant, age 69 ± 9 (SHORT) 26 with resurfacing, age 60 ± 8 (RESURF) 43 healthy control with no history of arthroplasty, age 59 ± 10 (CONTROL) All groups were matched for BMI and gender. Participants were asked to walk on an instrumented treadmill. Initially a 5 minute warm up at 4 km/h, then tests at increasing speed in 0.5 km/h increments. Maximum walking speed was determined by the patients themselves, or when subjects moved from walking to running. Ground reaction forces (GRF) were measured in 20 second intervals at each speed. Features were calculated based on the mean GRF for each trial, and on symmetry measures such as first peak force (heel strike), second peak force (toe-off), the rate at which the foot was loaded and unloaded, and step length.Introduction
Materials and Methods
Giant cell tumour (GCT) of bone is a benign but locally aggressive tumour. Although topical adjuvants have been used in the past, local recurrence following intralesional excision of GCT of bone continues to remain a problem. The use of bisphosphonates as an anti-osteoclastic agent in the management of osteolytic bone metastases is well accepted. Therefore our study aims to retrospectively demonstrate whether the administration of bisphosphonate as an adjuvant can control aggressive local recurrence of GCT and prevent wide resections of bones or amputations. A retrospective study was performed between 2004 and 2010. 6 patients were diagnosed with aggressive local recurrence of appendicular GCT. All patients were treated for the primary tumour by surgical curettage and cryoablation followed by cementation or biological reconstruction. In 5 patients the tumour was located in the distal radius and in one in the first metacarpal bone. All recurrences were in the bone with large soft-tissue extension. After histological diagnosis – by CT core needle biopsy – the patients were treated by intravenous bisphosphonate, followed by clinical & radiological assessments.Aim
Method
Cryosurgery is a well established modality in the treatment of benign aggressive and low grade malignant tumours. In this setting it allows for intra-lesional resection and preservation of function without compromising oncological outcome. Here we present the outcome of 87 patients treated with cryosurgery for low-grade chondrosarcoma of bone. 87 patients were treated between 1988 and 2005. The mean age was 51 years (range, 8-77 years), and included 47 females and 40 males. Minimal follow-up was two years. Patients were treated for lesions of the distal femur (n = 30), proximal humerus (n = 33), proximal femur (n = 5), proximal tibia (n = 10), and the remaining sites included the iliac bone, distal tibia, forearm, carpal and tarsal bones (n=10). Patients were treated with intralesional curettage through a cortical window, adjuvant burr drilling, cryotherpay and reconstruction with cement or bone graft and hardware fixation when that was clinically indicated.Background
Materials and methods
