Hip resurfacing arthroplasty (HRA) is currently regaining positive attention as a treatment of osteoarthritis in young, active individuals[1]. The procedure is complex and has low tolerance for implant malpositioning [2]. ‘Precision tools', such as imageless navigation and patient specific instruments, have been developed to assist with implant positioning but have not been shown to be fully reliable [3]. The aim of this study is to present and validate the first step of novel quality control tool to verify implant position intra-operatively. We propose that, before reaming of the femoral head, a handheld structured light 3D scanner can be used to assess the orientation and insertion point of femoral guide wire. Guide wires were placed into the heads of 29 solid foam synthetic femora. A specially designed marker (two orthogonal parallelepipeds attached to a shaft) was inserted into the guide wire holes. Each bone (head, neck and marker) was 3D scanned twice (fig 1). The insertion point and guide wire neck angle were calculated from the marker's parameters. Reference data was acquired with an optical tracking system. The measurements calculated with the 3D scans were compared to the reference ones to evaluate the precision. The comparison of the test retest measurements done with the new method are used to evaluate intra-rater variability.Introduction
Methods
Because of the low cost and easy access, surgical video has become a popular method of acquiring surgical skills outside operating rooms without disrupting normal surgical flow. However, currently existing video systems all use a single point of view (POV). Some complex orthopedic procedures, such as joint replacement, require a level of accuracy in several dimensions. So single and fixed POV video may not be enough to provide all the necessary information for educational and training purposes. The aim of our project was to develop a novel multiple POV video system and evaluate its efficacy as an aid for learning joint replacement procedure compared with traditional method. Based on the videos of a hip resurfacing procedure performed by an expert orthopedic surgeon captured by 8 cameras fixed all around the operating table, we developed a novel multiple POV video system which enables users to autonomously switch between optimal viewpoints (Figure 1). 30 student doctors (undergraduate years 3–5 and naive to hip resurfacing procedure) were recruited and randomly allocated to 2 groups: experiment group and control group, and were assigned to learn the procedure using multiple or single POV video systems respectively. Before learning they were first asked to complete a multiple choicetest designed using a modified Delphi technique with the advice and feedback sought from 4 experienced orthopedic surgeons to test the participants' baseline knowledge of hip resurfacing procedure. After video learning, they were asked to answer the test again to verify their gained information and comprehension of the procedure, followed by a 5-point Likert-scale questionnaire to demonstrate their self-perception of confidence and satisfaction with the learning experience. The scores in the 2 tests and in the Likert-scale questionnaire were compared between 2 groups using Independent-Samples t-test (for normally distributed data) or Mann-Whitney U test (for non-normally distributed data). Statistical significance was set as p<0.05.Introduction
Materials and Methods
The treatment of patients with osteoarthritis of the knee and associated extra-articular deformity of the leg is challenging. Current teaching recognises two possible approaches: (1) a total knee replacement (TKR) with intra-articular bone resections to correct the malalignment or (2) an extra-articular osteotomy to correct the malalignment together with a TKR (either simultaneously or staged). However, a number of these patients only have unicompartmental knee osteoarthritis and, in the absence of an extra-articular deformity would be ideal candidates for joint preserving surgery such as unicompartmental knee replacement (UKR) given its superior functional outcome and lower cost relative to a TKR [1). We report four cases of medial unicondylar knee replacement, with a simultaneous extra-articular osteotomy to correct deformity, using novel 3D printed patient-specific guides (Embody, UK) (see Figure 1). The procedure was successful in all four patients, and there were no complications. A mean increase in the Oxford knee score of 9.5, and in the EQ5D VAS of 15 was observed. To our knowledge this is the first report of combined osteotomy and unicompartmental knee replacement for the treatment of extra-articular deformity and knee osteoarthritis. This technically challenging procedure is made possible by a novel 3D printed patient-specific guide which controls osteotomy position, degree of deformity correction (multi-plane if required), and orientates the saw-cuts for the unicompartmental prosthesis according to the corrected leg alignment. Using 3D printed surgical guides to perform operations not previously possible represents a paradigm shift in knee surgery. We suggest that this joint preserving approach should be considered the preferred treatment option for suitable patients.
Normal human locomotion entails a rather narrow base of support (BoS), of around 12cm at normal walking speeds. This relatively narrow gait requires good balance, and is beneficial, as it minimises the adduction moment at the knee. Normal knees have a slightly oblique joint line, and slight varus, which allow the normal human to walk rapidly with a narrow BoS. Patients with increased varus and secondary osteoarthritis have a broader BoS, which exacerbates the excessive load, making walking painful and ungainly. We wondered if there would be a difference between the base of support of patients whose knee kinematics had been preserved, by retaining the native jointline obliquity and the acl, in comparison with those whose alignment had been altered to a mechanically correct ‘neutral’ alignment. Of 201 patients measured following knee arthroplasty, 31 unicondylar patients and 35 total knee patients, with a single primary arthroplasty, and no co-morbidities, over 1 year post-operatively were identified. Two control groups of controls, a younger cohort of 112 people and 17 in an age matched older cohort. All operations were performed by the same surgeon. The total knees were cruciate retaining devices, inserted in mechanical alignment, and the unicondylar knees were inserted retaining the native alignment and joint-line obliquity. The gait of all subjects was analysed on an instrumented, calibrated treadmill with underlying force plates. Patients start by walking at a comfortable speed for them for 5 minutes, before the speed of the treadmill is increased at 1/2 km/h increments until maximum walking speed obtained, spending 30 seconds at each. After the flat test, it was then repeated on a downhill slope of 6°. Base of Support is interpreted as the distance between the centre point of heel strike and toe off from one foot to that of the other. The top walking speed in the unicondylar group was significantly greater than that of the total knee group, as we reported in 2013. TKA patients have an average BoS of 14cm, while UKA patients and controls have a 12cm BoS. The BoS did not reduce with speed. This 2cm, or 17% increase in BoS is significant. Shapiro-Wilk tests demonstrate a normal distribution to the results, and ANOVA testing reveals a significant difference (p<0.05) within the groups between the speeds of 4.5 to 9. Post-Hoc Bonferroni testing reveal a significant difference between the TKA group and each of the other three groups. On the downhill test (figure 1), the mean BoS in the TKA group increased to 16cm. This increase is highly significant, with a p value of <0.001, while the increase in the UKA group at higher speeds failed to reach significance, and the controls both stayed at 12cm. 6 Bi-uni knees tested acted just like the UKAs. A narrow base of support minimises excessive loads across the joint line. Maintenance of jointline obliquity and an ACL enables this feature to be returned to normal following uni, or bi-uni, while a well aligned TKA seems to prevent it.Materials and Methods
Discussion
Opening wedge high tibial osteotomy is an attractive surgical option for physically active patients with early osteoarthritis and varus malalignment. Unfortunately use of this surgical technique is frequently accompanied by an unintended increase in the posterior tibial slope, resulting in anterior tibial translation, and consequent altered knee kinematics and cartilage loading(1). To address this unintended consequence, it has been recommended that the relative opening of the anteromedial and posterolateral corners of the osteotomy are calculated pre-operatively using trigonometry (1). This calculation assumes that the saw-cut is made parallel to the native posterior slope; yet given the current reliance on 2D images and the ‘surgeon's eye’ to guide the saw-cut, this assumption is questionable. The aim of this study was to explore how accurately the native posterior tibial slope is reproduced with a traditional freehand osteotomy saw-cut, and whether novel 3D printed patient-specific guides improve this accuracy. 26 fourth year medical students with no prior experience of performing an osteotomy were asked to perform two osteotomy saw-cuts in foam cortical shell tibiae; one freehand, and one with a 3D printed surgical guide (Embody, London) that was designed using a CT scan of the bone model. The students were instructed to aim for parallelity with a hinge pin which had been inserted (with the use of a highly conforming 3D printed guide) parallel to the posterior slope of the native joint. For the purpose of analysis, the sawbones were consistently orientated along their mechanical and anatomical tibial axes using custom moulded supports. Digital photographs taken in the plane of the osteotomy were analysed with ImageJ software to calculate the angular difference in the sagittal plane between the hinge-pin and saw-cut. Statistical analysis was performed with SPSS v21 (Chicago, Illinois); a paired t-test was used to compare the freehand and patient-specific guide techniques. Statistical significance was set at a p-value <0.05.Introduction
Methods
The Oxford Hip Score (OHS), the Harris Hip Score (HHS) and WOMAC are examples of patient reported outcome measures (PROMs) have well documented ceiling effects, with many patients clustered close to full marks following arthroplasty. Any arthroplasty that offers superior function would therefore fail to be detectable using these metrics. Two recent well conducted randomised clinical trials made exactly this error, by using OHS and WOMAC to detect a differences in outcome between hip resurfacing and hip arthroplasty despite published data already showing in single arm studies that these two procedures score close to full marks using both PROMS. We had observed that patients with hip resurfacing arthroplasty (HRA) were able to walk faster and with more normal stride length than patients with well performing hip replacements, but that these objective differences in gait were not captured by PROMs. In an attempt to capture these differences, we developed a patient centred outcome measure (PCOM) using a method developed by Philip Noble's group. This allows patients to select the functions that matter to them personally against which the success of their own operation will be measured. Our null hypothesis was that this PCOM would be no more successful than the OHS in discriminating between types of hip arthroplasty. 22 patients with a well performing Hip Resurfacing Arthroplasty were identified. These were closely matched by age, sex, BMI, height, preop diagnosis with 22 patients with a well performing conventional THA. Both were compared with healthy controls using the novel PCOM and in a gait lab. PROMs for the two groups were similar, while HRA scored higher in the PCOM. The 9% difference was significant (p<0.05). At top walking speed, HRA were 10% faster, with a 9% longer stride length. Outcome measures should be able to detect differences that are clinically relevant to patients and their surgeons. The currently used hip scores are not capable of delivering this distinction, and assume that most hip replacements are effectively perfect. While the function of hip replacements is indeed very good, with satisfaction rates high, objective measures of function are essential for innovators who are trying to deliver improved functional outcome. The 9% difference in PCOM found in this small study reflects the higher activity levels reported by many, and of similar magnitude to the 10% difference in top walking speed, despite no detectable difference in conventional PROMS. PCOMs may offer further insight into differences in function. For investigators who wish to develop improvements to hip arthroplasty, PCOMs and objective measures of gait may describe differences that matter more to patients than conventional hip scores.Results
Discussion
There has been a lot of focus on the value of anatomic tunnel placement in ACL reconstruction, and the relative merits of single and double bundle grafts. Multiple cadaveric and animal studies have compared the effects of tunnel placement and graft type on knee biomechanics. 45 patients who underwent ACL reconstruction were included into our study. Femoral tunnel position was analysed by two independent doctors using the radiographic quadrant method as described by Bernard et al., and the mean values calculated. Forty-one of these patients completed a KOOS questionnaire. The mean ratio ‘a’ was 26.57% and mean ratio ‘b’ was 30.04% as compared to 24.8% (+/− 2.2%) and 28.5% (+/− 2.5%) respectively quoted by Bernard et.al, as the ideal tunnel position. Only twenty-three of these femoral tunnels were in the anatomic range. Analysis of forty-one KOOS surveys (23 anatomic, 18 non-anatomic) revealed no significant difference in total score or subscales between the anatomic and non-anatomic groups (p= >0.05). Our study suggests that the ideal tunnel position, as described by Bernard et.al. may not be ideal and fixed.
Pyogenic spinal infection (PSI) is an increasingly common presentation to spinal units in the UK. Its investigation and diagnosis is often delayed. The purpose of this study was to determine the prognostic significance of the inflammatory marker levels on admission on achieving a positive microbiological diagnosis in patients with PSI. Retrospective case series review of all patients presenting with PSI to our unit.Objective
Study design
To report a retrospective study of 103 cases of primary spinal infection, the largest ever such series from the UK, analysing presenting symptoms, investigations, bacteriology and the results of treatment. This is a retrospective review of all patients (54 Male, 49 Female) treated for primary spinal infection in a Teaching Hospital in the UK.Purpose
Method
