Perthes disease often leaves young adults with hip joint incongruency due to femoral head asphericity, (extra-articular extrusion and superior flattening). This causes femoro-acetabular impingement, a reduced range of movement and early degenerative change. We report a novel method for restoration of femoral head sphericity and femoro-acetabular congruency. Two males (aged 21 and 22 years) presented with groin pain and severe hip stiffness after childhood Perthes disease. Imaging confirmed characteristic saddle shaped deformities of the femoral head, with cartilage loss overlying a central depression in the superior section of the head. A new method of treatment was proposed. Both cases were treated in the same manner. A surgical dislocation was performed with a trochanteric flip osteotomy. The extra-articular bump was removed with osteotomes and a burr to reduce femoro- acetabular impingement. The sphericity of the femoral head was restored using a HemiCap partial re-surfacing (Arthrosurface, MA, USA). The radius of the implant was selected to match that of the acetabulum. Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint. Both patients recovered without incident and were mobilised with crutches, restricted to touch weight-bearing for six weeks to protect union of the trochanteric osteotomy. At a minimum of three year follow-up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage. We conclude that this novel treatment functions well in the short term. Further surveillance is on-going to confirm that this treatment results in improved long term durability of the natural hip joint after Perthes disease.
Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint. At a minimum of 3 year follow up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage.
This study aims to develop a pre-operative protocol for the Australian population, regarding the safe number of screws and size of screw that may be placed. Additionally, results from the study may help identify patients at increased risk of injury during PCSP.
Safe corridor measurements of the PE and AC were taken in the control patients. Pelvic CT scans, taken as part of trauma protocol, were reconstructed using 3D modelling and the dimensions of the whole (3 dimensional) safe corridor measured. The accuracy of screw placement was determined in each treated patient. Accuracy was assessed by the screenshot method, the post-operative CT method or by both methods. In both methods, accuracy was taken as the deviation between the positions of the actual screw and planned screw.
The mean ± (standard deviation, SD) minimum measurement of the safe corridor at the PE was 15.6 ± 2.3 mm (range 11.6 mm to 20.2 mm) and at the AC was 5.9 ±1.6 mm (range 3.0 mm to 10.0 mm). The mean ± (SD) accuracy of screw placement was 6.1 ± 5.3 mm and ranged from a displacement of 1.3 mm to 16.1 mm.
There are several different ways of preparing the femoral canal prior to cementing a hip prosthesis. This study investigated the mechanical strength of the cement-bone interface of four different types of preparation determined by the maximum tensile force required to separate a cemented prosthesis from its cancellous bone origin. Forty-eight fresh-frozen ox femora were prepared for hip arthroplasty, In a four-way comparison, groups of eleven femora were prepared by irrigation using
syringe injected normal saline; hydrogen-peroxide soaked gauze; pulse-lavage brushing; and pulse-lavage brushing and hydrogen-peroxide soaked gauze combination. Specimens were secured to a Material-test System (MTS), and the femoral implant pulled from the femur uni-axially at a rate of 5mm/min. The ‘pull-out strength’ was defined as the maximum tension recorded by the MTS during separation. Cement interdigitation was also inspected for each technique by microscopy of eight bone-implant transverse sections taken from prepared specimens. Following an analysis of variance and pair-wise Fisher comparison, the average pull-out strength of the cemented prosthesis was significantly higher (P<
0.001) using pulse-lavage brushing (mean 8049.2 N), and pulse-lavage brushing in combination with hydrogen-peroxide soaked gauze (mean 8489.1 N), than with normal saline irrigation (mean 947.1 N) or hydrogen-peroxide soaked gauze preparation (mean 1832.6 N). Prosthesis pull-out strength following pulse-lavage brushing in combination with hydrogen-peroxide soaked gauze was not significantly different (P>
0.05) than preparing with pulse-lavage brushing alone. Low and high power microscopy of specimen transverse sections revealed the greatest levels of cement penetration in specimens prepared using pulse-lavage brushing. This study demonstrated that one of the most effective preparations of the femoral canal for optimal mechanical fixation between cement and cancellous bone is pulse- lavage brushing. The use of hydrogen-peroxide soaked gauze in femoral canal preparation, either alone or in combination with pulse-lavage brushing, may not significantly improve prosthesis fixation.
Traditionally autologous bone graft is the standard treatment for non-union of fractures. More recently osteo-inductive agents with or without allograft have been utilised. A trial of Autologous Mesenchymal Precursor Cells has been completed at the Royal Melbourne Hospital to investigate their potential for the treatment of nonunion of long bone fractures. With the approval of the ethics committee at the Royal Melbourne Hospital a human safety trial was commenced for the treatment of fracture non-union. Bone marrow cells were harvested from patients approximately six weeks before surgery and cultured in a laboratory. The cells were expanded in a culture medium. At the time of definitive surgery the stem cells were implanted on a hydroxy apatite/tricalcium phosphate matrix to the non-union site. Any further fixation that was required at the time of the union was performed by the treating surgeon. Investigations were performed at regular intervals to assess for union and for any reaction to the stem cells and growth medium. The trial has been completed and eleven patients have been entered into the study. There were eight patients with non-union of femoral fractures and four patients with tibial non-unions (one patient with ipsilateral injuries to both bones). The average age was 41.9 years and the mean time to surgery from the initial injury was 15.2 months. Eight patients have united at a mean time of 24 weeks. One is well on the way to union and of the remaining two patients one is listed as uncertain and one a declared non union. The patient who has failed to unite is currently awaiting further surgery. One patient withdrew from the trial after ceasing smoking and finally uniting prior to stem cell implantation. There has been one adverse event with possible infection at a screw site though this was thought not to be related to stem cell therapy. This is a phase one safety trial of a new development for the treatment of a nonunion of long bone fractures. The results are promising with the regards to achieving bone union without any significant complications. This paves the way for a trial involving allogeneic stem cells.
Computer navigation was introduced in Australia in 2000, initially with the use of pre-operative computer scans and then later with image free systems. In 2003 the AOA – NJRR began collecting data for knee replacement performed with computer navigation. Meta analysis of the literature has shown better coronal and sagittal plane alignment in total knee arthroplasty performed with computer navigation as opposed to standard instrumented knee replacement. At present, however, there is no data on improved outcomes or reduced revision rates. Information was requested from the AOA – NJRR on the use of computer navigation for both uni-compartmental and total knee replacements. This included numbers of navigated knees done per year as well as revision rates and reasons for revisions of knees performed by computer navigation surgery. Since data collection began there has been 2,651 computer assisted total knee replacements performed which is 4.1% of the total number of knee replacements in this time period. There has been a steady increase in the last three years in the use of computer navigation. There has been an increased number of computer navigated knees performed in the private hospital sector as opposed to the public hospitals and there is a state by state variation in the uptake of navigation. The revision rate per 100 observed ‘component’ years at three years is 2.8 for non computer assisted and 2.5 computer assisted surgery. This is not statistically significant. There is no difference in the early complication rate leading to revision. The use of computer navigation could be expected to reduce the long term revision rates of knee arthroplasty due to better alignment and potentially less wear. In the short term there is no significant revision rate between the two methods of performing TKR particularly with regard to infection or fracture
Correct alignment is important for success in total knee replacement. Currently this is achieved by a combination of intramedullary and extramedullary alignment using jigs and cutting blocks. This multicentre study evaluates the use of computer assisted planning and the interactive guidance of instruments for total knee replacement. Prior to surgery computer scans of the hip, knee and ankle were performed of patients enrolled in the study. Pre operative planning of the position and size of the knee components was performed by the surgeon using a CT based Vector Vision Navigation System (Brain LAB AG, Heimstetten, Germany). P.F.C.x (De Puy Leeds UK) knee replacements were then implanted in 38 patients. Surgery was carried out according to the standard surgical technique using traditional instruments. Information of the planned and intraoperatively recorded position of the cutting blocks were analysed to check varus/valgus alignment, flexion/extension alignment, the amount of planned resection from both the femoral and tibial bones and the size of the components. Information from all the separate centres was sent to a central data processing base for analysis. Results were calculated comparing the differences between the planned and performed cuts for each of the different variables studied. Graphs demonstrate the differences in the alignment between that planned by the surgical navigation system and what was actually carried out by the instrumented cuts. Based on the data obtained from the multicentre study we have concluded that the planned position of the implants using the standard instruments was similar to that using the Vector Vision Navigation System. We believe that it is safe to proceed with surgical navigation total knee arthroplasty using the P.F.C.x total knee prosthesis with Image Guided Surgery and a further multicentre study is currently underway evaluating this.