There have been few reports regarding the efficacy of posterior instrumentation alone as surgical treatment for patients with pyogenic spondylitis, thus avoiding the morbidity of anterior surgery. We report the clinical outcomes of six patients with pyogenic spondylitis treated effectively with a single-stage posterior fusion without anterior debridement at a mean follow-up of 2.8 years (2 to 5). Haematological data, including white cell count and level of C-reactive protein, returned to normal in all patients at a mean of 8.2 weeks (7 to 9) after the posterior fusion. Rigid bony fusion between the infected vertebrae was observed in five patients at a mean of 6.3 months (4.5 to 8) post-operatively, with the remaining patient having partial union. Severe back pain was immediately reduced following surgery and the activities of daily living showed a marked improvement. Methicillin-resistant Staphylococcus aureus was detected as the causative organism in four patients. Single-stage posterior fusion may be effective in patients with pyogenic spondylitis who have relatively minor bony destruction

Glenoid baseplate positioning for reverse total shoulder replacements (rTSR) is key for stability and longevity. 3D planning and image-derived instrumentation (IDI) are techniques for improving implant placement accuracy. This is a single-blinded randomised controlled trial comparing 3D planning with IDI jigs versus 3D planning with conventional instrumentation. Eligible patients were enrolled and had 3D pre-operative planning. They were randomised to either IDI or conventional instrumentation; then underwent their rTSR. 6 weeks post operatively, a CT scan was performed and blinded assessors measured the accuracy of glenoid baseplate position relative to the pre-operative plan. 47 patients were included: 24 with IDI and 23 with conventional instrumentation. The IDI group were more likely to have a guidewire placement within 2mm of the preoperative plan in the superior/inferior plane when compared to the conventional group (p=0.01). The IDI group had a smaller degree of error when the native glenoid retroversion was >10° (p=0.047) when compared to the conventional group. All other parameters (inclination, anterior/posterior plane, glenoids with retroversion <10°) showed no significant difference between the two groups. Both IDI and conventional methods for rTSA placement are very accurate. However, IDI is more accurate for complex glenoid morphology and placement in the superior-inferior plane. Clinically, these two parameters are important and may prevent long term complications of scapular notching or glenoid baseplate loosening. Image-derived instrumentation (IDI) is significantly more accurate in glenoid component placement in the superior/inferior plane compared to conventional instrumentation when using 3D pre-operative planning. Additionally, in complex glenoid morphologies where the native retroversion is >10°, IDI has improved accuracy in glenoid placement compared to conventional instrumentation. IDI is an accurate method for glenoid guidewire and component placement in rTSA

Aims. The aim of this study was to investigate the incidence and characteristics of instrumentation failure (IF) after total en bloc spondylectomy (TES), and to analyze risk factors for IF. Methods. The medical records from 136 patients (65 male, 71 female) with a mean age of 52.7 years (14 to 80) who underwent TES were retrospectively reviewed. The mean follow-up period was 101 months (36 to 232). Analyzed factors included incidence of IF, age, sex, BMI, history of chemotherapy or radiotherapy, tumour histology (primary or metastasis; benign or malignant), surgical approach (posterior or combined), tumour location (thoracic or lumbar; junctional or non-junctional), number of resected vertebrae (single or multilevel), anterior resection line (disc-to-disc or intravertebra), type of bone graft (autograft or frozen autograft), cage subsidence (CS), and local alignment (LA). A survival analysis of the instrumentation was performed, and relationships between IF and other factors were investigated using the Cox regression model. Results. A total of 44 patients (32.4%) developed IF at a median of 31 months (interquartile range 23 to 74) following TES. Most IFs were rod fractures preceded by a mean CS of 6.1 mm (2 to 18) and LA kyphotic enhancement of 10.8° (-1 to 36). IF-free survival rates were 75.8% at five years and 56.9% at ten years. The interval from TES to IF peaked at two to three years postoperatively and continued to occur over a period of time thereafter; the early IF-developing group had greater CS at one month postoperatively (CS1M) and more lumbar TES. CS1M ≥ 3 mm and sole use of frozen autografts were identified as independent risk factors for IF. Conclusion. IF is a common complication following TES. We have demonstrated that robust spinal reconstruction preventing CS, and high-quality bone grafting are necessary for successful reconstruction. Cite this article: Bone Joint J 2023;105-B(2):172–179

Anterior instrumentation is an established method of correcting King I adolescent idiopathic scoliosis. Posterior segmental pedicle screw instrumentation, with its more powerful corrective force over hooks, could offer significant advantages. The purpose of our study is to compare the results of anterior instrumentation versus segmental pedicle screw instrumentation in adolescent idiopathic thoracolumbar scoliosis. A retrospective analysis was conducted on 36 consecutive female patients with adolescent idiopathic thoracolumbar scoliosis who had surgery from December 1997. All had a minimum of two year follow-up. Eleven patients had posterior surgery performed on them. Mean age at surgery was similar between both groups. Length of surgery was significantly shorter in the posterior group (189 minutes versus 272 minutes). Length of hospital stay was shorter in the posterior group (6.2 days versus eight days). Estimated blood loss, duration of analgesia, and ICU stay did not differ significantly between the two groups. No complications were encountered in both groups at latest follow-up. The magnitudes and flexibility of the thoracolumbar curves did not differ significantly between the two groups. The number of levels in the major curve was also similar between the groups. Fusion levels were shorter in the anterior group (mean 4.1 versus 5.0). The percentage correction of scoliosis was similar between the two groups at all stages of follow-up, being 74% at one week post-surgery, 70% at six months post-surgery, 68% at one year post-surgery and latest follow-up in the anterior group; and 71% at one week post-surgery, 67% at six months post-surgery, 68% at one year post-surgery, and 67% at latest follow-up in the posterior group. Thoracolumbar sagittal alignment at T11 to L2 was maintained for both groups throughout the follow-up period. The incidence of proximal junctional kyphosis was higher in the posterior group (p < 0.01). In conclusion, surgical correction of both the frontal and sagittal plane deformity are comparable to anterior instrumentation. Shorter length of surgery and hospital stay are the potential benefits of posterior surgery. Posterior segmental pedicle screw instrumentation offers significant advantage, and is a viable alternative to standard anterior instrumentation in idiopathic thoracolumbar scoliosis

Adolescent idiopathic scoliosis in 152 patients was treated by Luque L-rod instrumentation and early mobilisation without external support. This series was compared with a matched group of 156 patients treated by Harrington instrumentation and immobilised in an underarm jacket for nine months. All the operations in both groups were performed by one surgeon and the patients were followed prospectively for more than two years. Correction of the scoliosis in the frontal plane was similar in both groups. However, the normal sagittal contour was better maintained with Luque rods, especially in the thoracolumbar and lumbar regions, and provided less loss of correction than with Harrington rods. Neither method significantly derotated the scoliosis. All the patients with Luque instrumentation developed a solid fusion despite breakage of the sublaminar wires at one or two levels in 4.9%. There were no major neurological complications with either type of instrumentation

Despite past advances of implant technologies, complication rates of fixations remain high at challenging sites such as the proximal humerus [1]. These may not only be owed to the implant itself but also to dissatisfactory surgical execution of fracture reduction and implant positioning. Therefore, the aim of this study was to quantify the instrumentation accuracy of a highly standardised and guided procedure and its influence on the biomechanical outcome and predicted failure risk. Preoperative planning of osteotomies creating an unstable 3-part fracture and fixation with a locking plate was performed based on CT scans of eight pairs of low-density proximal humerus samples from elderly female donors (85.2±5.4 years). 3D-printed subject-specific guides were used to osteotomise and instrument the samples according to the pre-OP plan. Instrumentation accuracies in terms of screw lengths and orientations were evaluated by comparing post-OP CT scans with the pre-OP plan. The fixation constructs were biomechanically tested until cyclic cut-out failure [2]. Failure risks of the planned and the post-OP configurations were predicted using a validated sample-specific finite element (FE) simulation approach [2] and correlated with the experimental outcomes. Small deviations were found for the instrumented screw trajectories compared to the planned configuration in the proximal-distal (0.3±1.3º) and anterior-posterior directions (-1.7±1.8º), and for screw tip to joint distances (-0.3±1.1 mm). Significantly higher failure risk was predicted for the post-OP compared to the planned configurations (p<0.01) via FE. When incorporating the instrumentation inaccuracies, the biomechanical results could be predicted well with FE (R. 2. =0.70). Despite the high instrumentation accuracy achieved using sophisticated subject-specific 3D-printed guides, even minor deviations from the pre-OP plan significantly increased the FE-predicted risk of failure. This underlines the importance of intraoperative guiding technology [3] in tandem with careful pre-OP planning to assist surgeons to achieve optimal outcomes. Acknowledgements. This study was performed with the assistance of the AO Foundation via the AOTRAUMA Network

We present a new technique for TKA implantation which utilizes patient-specific femoral and tibial positioning guides developed from MRI to offer an individualized approach to total knee replacement. This is a prospective non controlled study which aims to analyse the precision of this technique, its advantages and inconvenients in comparison with the conventional instrumented technique. Material. The MRI provides a consistent three-dimensional data set of the patient's anatomy which allows for 3D axis identification. The ideal position and sizing is performed by the surgeon on this 3D model and the patient specific guides are manufactured in advance in order to reproduce the bone cuts corresponding to this positioning and implant size. There are no intramedullary nor extramedullary instruments during the surgery. Method. We compared 20 patients operated with this technique with 20 patients operated with the conventional technique. The hypothesis was a difference < 2° between the 2 techniques. The measured parameters were:. HKS, HKA, tibial slope, femoral rotation on CT. Duration, bleeding, pain on VAS and morphine consumption, active flexion, KSS, Oxford score, recovery of independant walking and delay of return to home. Both groups were identical for gender, age, BMI, etiology, comorbidities, pain and rehabilitation protocols. Results. There were no significant differences on HKA, HKS angles, femoral rotation, active flexion, pain, length of hospital stay. The surgery with the patient specific instruments was 10 minutes shorter than the conventional one (p < 0,05) and the bleeding was inferior with a ratio of 1/3 (p=0,02). There were no complications with this technique and the use of the conventional guides were never necessary with the patient specific instrumentation. Discussion and Conclusion. The patient specific instrumentation for TKA has a precision identical to that of the conventional technique, including for femoral rotation and ligament balance. The advantages of this method are:. Reduced per and post operative bleeding. Shortening of the operative procedure. It is reproducible, including for less experimented surgeons and allows teaching and assistance in a lower technological institution. The number of implant sizes is much inferior (2/9) just as the quantity of instruments to be sterilised. These advantages induce a cost reduction which could be inferior to the price of the procedure

Aims. The aim of this study was to evaluate whether, after correction of an adolescent idiopathic scoliosis (AIS), leaving out the subfascial drain gives results that are no worse than using a drain in terms of total blood loss, drop in haemoglobin level, and opioid consumption. Methods. Adolescents (aged between 10 and 21 years) with an idiopathic scoliosis (major curve ≥ 45°) were eligible for inclusion in this randomized controlled noninferiority trial (n = 125). A total of 90 adolescents who had undergone segmental pedicle screw instrumentation were randomized into no-drain or drain groups at the time of wound closure using the sealed envelope technique (1:1). The primary outcome was a drop in the haemoglobin level during first three postoperative days. Secondary outcomes were 48-hour postoperative oxycodone consumption and surgical complications. Results. All 90 patients were included in the primary outcome analysis (no drain = 43; drain = 47). The mean total postoperative blood loss (intraoperative and drain output) was significantly higher in the group with a subfascial drain than in the no-drain group (1,008 ml (SD 520) vs 631 ml (SD 518); p < 0.001). The drop in haemoglobin level did not differ between the study groups over the postoperative timepoints (p = 0.290). The 48-hour opioid consumption was significantly higher in the no-drain group (2.0 mg/kg (SD 0.9) vs 1.4 (SD 0.6); p = 0.005). Two patients in the no-drain and one patient in the drain group developed a surgical site infection. Conclusion. Leaving the subfascial drain out after pedicle screw instrumentation for AIS is not associated with higher postoperative haemoglobin levels. Patients treated without a subfascial drain needed 30% more opioids during the first 48 hours than those who had a drain. Cite this article: Bone Joint J 2022;104-B(9):1067–1072

Aims. The aim of this study was to evaluate the outcome of spinal instrumentation in haemodialyzed patients with native pyogenic spondylodiscitis. Spinal instrumentation in these patients can be dangerous due to rates of complications and mortality, and biofilm formation on the instrumentation. Patients and Methods. A total of 134 haemodialyzed patients aged more than 50 years who underwent surgical treatment for pyogenic spondylodiscitis were included in the study. Their mean age was 66.4 years (50 to 83); 66 were male (49.3%) and 68 were female (50.7%). They were divided into two groups according to whether spinal instrumentation was used or not. Propensity score matching was used to attenuate the potential selection bias. The outcome of treatment was compared between these two groups. Results. A total of 89 patients (66.4%) underwent non-instrumented surgery and 45 (33.5%) underwent instrumented surgery. There were no significant differences in the rates of postoperative complications, except for an increased rate of wound problems in the instrumented group, which was found in the unmatched cohorts (p = 0.034). There were no significant differences in the rate of recurrent infections (p = 0.328 for the unmatched cohort; p = 0.269 for the matched cohort) and mortality rate, including in-hospital (p = 0.713 for the unmatched cohort; p = 0.738 for the matched cohort) and one-year rates (p = 0.363 for the unmatched cohort; p = 0.787 for the matched cohort), between the groups. However, the interval between the initial diagnosis and the first recurrence was significantly longer in the instrumented group (p = 0.008 for the unmatched cohort; p = 0.032 for the matched cohort). Conclusion. Instrumented surgery for haemodialyzed patients with pyogenic spondylodiscitis showed similar outcomes, including recurrence and mortality, to non-instrumented surgery, despite the instrumented group having more severe neurological deficit, a larger number of involved levels, and increased kyphotic angle

The aim of this study was to report the restauration of the normal vertebral morphology and the absence of curve progression after removal the instrumentation in AIS patients that underwent posterior correction of the deformity by common all screws construct whitout fusion. A series of 36 AIS immature patients (Risser 3 or less) were include in the study. Instrumentation was removed once the maturity stage was complete (Risser 5). Curve correction was assessed at pre and postoperative, before instrumentation removal, just post removal, and more than two years after instrumentation removal. Epiphyseal vertebral growth modulation was assessed by a coronal wedging ratio (WR) at the apical level of the main curve (MC). The mean preoperative coronal Cobb was corrected from 53.7°±7.5 to 5.5º±7.5º (89.7%) at the immediate postop. After implants removal (31.0±5.8 months) the MC was 13.1º. T5–T12 kyphosis showed a significant improvement from 19.0º before curve correction to 27.1º after implants removal (p<0.05). Before surgery, WR was 0.71±0.06, and after removal WR was 0.98±0.08 (p<0.001). At the end of follow-up, the mean sagittal range of motion (ROM) of the T12-S1 segment was 51.2±21.0º. SRS-22 scores improved from 3.31±0.25 preoperatively to 3.68±0.25 at final assessment (p<0.001). In conclusion, fusionless posterior approach using a common all pedicle screws construct correct satisfactory scoliotic main curves and permits removal of the instrumentation once the bone maturity is reached. The final correction was highly satisfactory and an acceptable ROM of the previously lower instrumented segments was observed

Introduction. The degree of glenoid bone loss associated with primary glenohumeral osteoarthritis can influence the type of glenoid implant selected and its placement in total shoulder arthroplasty (TSA). The literature has demonstrated inaccurate glenoid component placement when using standard instruments and two-dimensional (2D) imaging without templating, particularly as the degree of glenoid deformity or bone loss worsens. Published results have demonstrated improved accuracy of implant placement when using three-dimensional (3D) computed tomography (CT) imaging with implant templating and patient specific instrumentation (PSI). Accurate placement of the glenoid component in TSA is expected to decrease component malposition and better correct pathologic deformity in order to decrease the risk of component loosening and failure over time. Different types of PSI have been described. Some PSI use 3D printed single use disposable instrumentation, while others use adjustable and reusable-patient specific instrumentation (R-PSI). However, no studies have directly compared the accuracy of different types of PSI in shoulder arthroplasty. We combined our clinical experience and compare the accuracy of glenoid implant placement with five different types of instrumentation when using 3D CT imaging, preoperative planning and implant templating in a series of 173 patients undergoing primary TSA. Our hypothesis was that all PSI technologies would demonstrate equivalent accuracy of implant placement and that PSI would show the most benefit with more severe glenoid deformity. Discussion and Conclusions. We demonstrated no consistent differences in accuracy of 3D CT preoperative planning and templating with any type of PSI used. In Groups 1 and 2, standard instrumentation was used in a patient specific manner defined by the software and in Groups 3, 4, and 5 a patient specific instrument was used. In all groups, the two surgeons were very experienced with use of the 3D CT preoperative planning and templating software and all of the instrumentation prior to starting this study, as well as very experienced with shoulder arthroplasty. This is a strength of the study when defining the efficacy of the technology, but limits the generalizability of the findings when considering the effectiveness of the technology with surgeons that may not have as much experience with shoulder arthroplasty and/or the PSI technology. Conversely, it could be postulated that greater improvements in accuracy may be seen with the studied PSI technology, when compared to no 3D planning or PSI, with less experienced surgeons. There could also be differences between the PSI technologies when used by less experienced surgeons, either across all cases or based upon the severity of pathology. When the surgeon is part of the method, the effectiveness of the technology is equally dependent upon the surgeon using the technology. A broader study using different surgeons is required to test the effectiveness of this technology. Comparing the results of this study with published results in the literature, 3D CT imaging and implant templating with use of PSI results in more accurate placement of the glenoid implant when compared to 2D CT imaging without templating and use of standard instrumentation. In previous studies, this was most evident in patients with more severe bone deformity. We believe that 3D CT planning and templating provides the most value in defining the glenoid pathology, as well as in the selection of the optimal implant and its placement. However, it should be the judgment of the surgeon, based upon their experience, to select the instrumentation to best achieve the desired result

Computer-assisted orthopaedic surgery (CAOS) improves mechanical alignment and the accuracy of surgical cuts in the context of total knee arthroplasty. A simplified, CAOS enhanced instrumentation system was assessed to determine if the same effects could be achieved through the use of a less intrusive system. Two cohorts of surgeons (experienced and trainees) performed a series of total knee arthroplasty resections in knee models with and without navigation-enhanced instrumentation. The percentage of resections that deviated from the planned cut by more than 2°or 2mm (outliers) was determined by post-resection advanced imaging for six unique outcome metrics. Within each experience level, the use of the CAOS enhanced system significantly reduced the total percentage of outliers as compared to conventional instrumentation (Figure 1). The experienced users improved from 35% to 4% outliers overall (p < .001) and the trainees from 34% to 10% outliers (p < .001). Comparing across experience levels, the experienced surgeons performed significantly better in only a single resection metric with conventional instrumentation (Figure 2A), varus/valgus tibial alignment, with 8.3% outliers compared to the trainee's 63% outliers (p = .004). The use of CAOS enhanced instrumentation eliminated any differences between the two user groups for all measured resections (Figure 2B). Comparing CAOS enhanced to conventional instrumentation specifically between anatomical deformity types revealed that there is significant improvement (p < .05) with the use of enhanced instrumentation for all three deformity types (Figure 3). These results suggest that non-intrusive CAOS enhanced instrumentation is a viable alternative to conventional instrumentation with possible benefits. This trial also demonstrates that additional experience may not correlate to improved surgical accuracy, and outliers may be less a result of individual surgeon ability or specific anatomic deformities, and more so related to limitations of the instrumentation used or other yet unidentified factors

Introduction. Total knee arthroplasty is a highly effective procedure to improve the quality of life in patients with advanced osteoarthritis. The number of these procedures are expected to grow 174% by 2030. This growth rate is expected to economically strain the health care system. A potential solution to alleviate this problem is the utilization of single use instruments (SUI). Potential advantages of SUI include: improved operating room efficiencies, decreased costs associated with traditional instrument management (sterile processing, shipping), and decreased infection risk. The present study examines the clinical results of SUI compared to standard instrumentation. Furthermore, economic modeling is performed to examine the cost savings that is potentially realized with their use. Materials and Methods. 51 patients receiving a TKA with use of SUI were prospectively compared to 49 patients utilizing standard instrumentation. Knee Society Scores and Radiographic alignment will be evaluated. Adverse events will be recorded. Economic modeling of SUI will be performed in 4 different areas: 1. Decreased infection burden; 2. Operating room logistics; 3. Sterile processing savings; and 4. Instrument logistical savings. Results. The average Pre-operative KSS (Objective/Functional) scores were 48.7/41.6 for the SIU patients compared to 50.2/38.7 for the standard instrumentation patients. Post-operative improvements measured 84.0/72.8 and 83.9/76.4 for the 2 groups respectively. The Pre-operative Hip-Knee-Ankle Angle was 176.2 and 177.0 for the 2 groups. The SUI HKA improved to 179.3 while the standard improved to 178.9. There were no statistical differences between the 2 groups. Furthermore, there were no cases of subsidence, migration, loosening, or infection in either group. There were no SUI procedure abandonments. Economic analysis revealed a decreased risk of Infection burden of $28.08/case. Operating room efficiencies include reduced set-up/take-down time and case efficiency savings/case. This averages $348.14/case. Instrument sterilization savings occur by bypassing the central sterile-processing department completely and models to $700/case. Finally, instrument logistics savings include time and money spent organizing/turning over/shipping instrument sets for cases. This estimate is $112.88/case for a total economic value of $1, 189.10/case. Discussion. In summary, the present study confirms that SUI provides similar clinical and radiographic results to standard instrumentation for TKA. Furthermore, SUI offers significant cost savings/case via potential benefits of reduced risk of infection, increased operating room productivity, and significant tray sterilization and loaner instrumentation cost savings

Aims. Loosening of pedicle screws is a major complication of posterior spinal stabilisation, especially in the osteoporotic spine. Our aim was to evaluate the effect of cement augmentation compared with extended dorsal instrumentation on the stability of posterior spinal fixation. Materials and Methods. A total of 12 osteoporotic human cadaveric spines (T11-L3) were randomised by bone mineral density into two groups and instrumented with pedicle screws: group I (SHORT) separated T12 or L2 and group II (EXTENDED) specimen consisting of T11/12 to L2/3. Screws were augmented with cement unilaterally in each vertebra. Fatigue testing was performed using a cranial-caudal sinusoidal, cyclic (1.0 Hz) load with stepwise increasing peak force. Results. Augmentation showed no significant increase in the mean cycles to failure and fatigue force (SHORT p = 0.067; EXTENDED p = 0.239). Extending the instrumentation resulted in a significantly increased number of cycles to failure and a significantly higher fatigue force compared with the SHORT instrumentation (EXTENDED non-augmented + 76%, p < 0.001; EXTENDED augmented + 87%, p < 0.001). Conclusion. The stabilising effect of cement augmentation of pedicle screws might not be as beneficial as expected from biomechanical pull-out tests. Lengthening the dorsal instrumentation results in a much higher increase of stability during fatigue testing in the osteoporotic spine compared with cement augmentation. Cite this article: Bone Joint J 2016;98-B:1099–1105

Total knee arthroplasty is a successful procedure that reduces knee pain and improves function in most patients with knee osteoarthritis. Patient dissatisfaction however remains high, and along with implant longevity, may be affected by component positioning. Surgery in obese patients is more technically challenging with difficulty identifying appropriate landmarks for alignment and more difficult exposure of the joint. Patient specific instrumentation (PSI) has been introduced with the goal to increase accuracy of component positioning by custom fitting cutting guides to the patient using advanced imaging. A strong criticism of this new technology however, is the cost associated. The purpose of this study was to determine, using a prospective, randomized-controlled trial, the cost-effectiveness of PSI compared to standard instrumentation for total knee arthroplasty in an obese patient population. Patients with a body mass index greater than 30 with osteoarthritis and undergoing a primary total knee arthroplasty were included in this study. We randomized patients to have their procedure with either standard instrumentation (SOC) or PSI. At 12-weeks post-surgery patients completed a self-reported cost questionnaire and the Western Ontario and McMaster Osteoarthritis Index (WOMAC). We performed a cost-effectiveness analyses from a public health payer and societal perspective. As we do not know the true cost of the PSI instrumentation, we estimated a value of $100 for our base case analysis and used one-way sensitivity analyses to determine the effect of different values (ranging from $0 to $500) would have on our conclusions. A total of 173 patients were enrolled in the study with 86 patients randomized to the PSI group and 87 to the SOC group. We found the PSI group to be both less effective and more costly than SOC when using a public payer perspective, regardless of the cost of the PSI. From a societal perspective, PSI was both less costly, but also less effective, regardless of the cost of the PSI. The mean difference in effect between the two groups was −1.61 (95% CI −3.48, 026, p=0.091). The incremental cost-effectiveness ratio was $485.71 per point increase in the WOMAC, or $7285.58 per clinically meaningful difference (15 points) in the WOMAC. Overall, our results suggest that PSI is not cost-effective compared to standard of care from a public payer perspective. From a societal perspective, there is some question as to whether the decreased effect found with the PSI group is worth the reduced cost. The main driver of the cost difference appears to be time off of volunteer work, which will need to be investigated further. In future, we will continue to follow these patients out to one year to collect cost and effectiveness data to investigate whether these results remain past 12 weeks post-surgery

Less invasive single-rod fusion technique may be indicated in the management of NMS to minimise operative time, blood loss and wound-related complications. This retrospective 12-year cohort study (2008–2020) aims to evaluate and compare the outcomes of this technique to the current standard dual rod technique to determine their safety and efficacy. 28 patients in the single rod group (Mean age = 16.4 [SD ±4.0]) and 30 in the double rod group (Mean age = 16.3 [SD±3.5]). Indications included a minimum 2 year follow period, detailed information on the type of implant and a complete pre- and post-operative imaging and medical records. Baseline demographics, comorbidities, and surgical characteristics were collected. Outcomes assessed included the immediate post-op and final follow up angles and general complications. All outcome analysis was performed using a regression approach. Angles at final follow-up: lumbar (Difference ratio (DR)= 2.60 [95% CI 0.37 – 18.4], p=0.25), thoracic (DR= 1.08 [95% CI 0.19 – 6.28], p=0.92), thoracolumbar (major curve angle) (DR 1.35 [95% CI 0.60 – 3.06], p=0.46) and kyphosis (DR = 0.97 [0.66, 1.42] p=0.86). There was no statistically significant difference, between the two groups, for any of the above angle outcomes as well as for length of surgery, blood loss and complication outcomes. Both single and double rod instrumentation achieves satisfactory and safe deformity correction which is maintained at final follow up. A larger scale study is warranted to further assess these techniques while also conducting a cost-benefit analysis between them

Introduction. In daily clinical practice, progression of spinal fusion is typically monitored during clinical follow-up using conventional radiography and Computed Tomography scans. However, recent research has demonstrated the potential of implant load monitoring to assess posterolateral spinal fusion in an in-vivo sheep model. The question arises to whether such a strain sensing system could be used to monitor bone fusion following lumbar interbody fusion surgery, where the intervertebral space is supported by a cage. Therefore, the aim of this study was to test human cadaveric lumbar spines in two states: after a transforaminal lumbar interbody fusion (TLIF) procedure combined with a pedicle-screw-rod-construct (PSR) and subsequently after simulating bone fusion. The study hypothesized that the load on the posterior instrumentation decreases as the segment stiffens due to simulated fusion. Method. A TLIF procedure with PSR was performed on eight human cadaveric spines at level L4-L5. Strain sensors were attached bilaterally to the rods to derive implant load changes during unconstrained flexion-extension (FE), lateral bending (LB) and axial rotation (AR) loads up to ±7.5Nm. The specimens were retested after simulating bone fusion between vertebrae L4-L5. In addition, the range of motion (ROM) was measured during each loading mode. Result. The ROM decreased in the simulated bone fusion state in all loading directions (p≤0.002). In both states, the measured strain on the posterior instrumentation was highest during LB motion. Furthermore, the sensors detected a significant decrease in the load induced rod strain (p≤0.002) between TLIF+PSR and simulated bone fusion state in LB. Conclusion. Implant load measured via rod strain sensors can be used to monitor the progression of fusion after a TLIF procedure when measured during LB of the lumbar spine. However, further research is needed to investigate the influence of daily loading scenarios expected in-vivo on the overall change in implant load

Abstract. Background. Since 2012 we have routinely used the cementless Oxford medial unicompartmental knee arthroplasty (mUKA), with microplasty instrumentation, in patients with anteromedial osteoarthritis (AMOA) meeting modern indications. We report the 10-year survival of 1000 mUKA with minimum 4-year follow-up. Methods. National Joint Registry (NJR) surgeon reports were interrogated for each senior author to identify the first 1,000 mUKAs performed for osteoarthritis. A minimum of 4 years follow-up was required. There was no loss to follow-up. The NJR status of each knee was established. For each mUKA revision the indication and mechanism of failure was determined using local patient records. The 10-year implant survival was calculated using life-table analysis. Results. The 1,000 mUKA cohort represented 55% of all primary knee replacements in the period, with an average age of 67.7 years and a 54%/46% male/female split. There were 17 revisions (11 for arthritis progression, 4 infections, 1 dislocation and 1 aseptic loosening). The 10-year survival was 98% (44 at risk in 10th year). One patient sustained a periprosthetic fracture at 3 weeks, treated with buttress plate fixation. Discussion. This is the first detailed series reporting the long-term outcome of the cementless Oxford mUKA implanted using microplasty instrumentation. There was a low failure rate, with only one revision for aseptic loosening. Lateral progression was the commonest cause for revision, with an incidence of 1%. This report provides evidence that the combination of evidence-based indications, well-designed instrumentation and cementless fixation can provide excellent long-term survival for the Oxford mUKA in treating AMOA

The medial opening-wedge high tibial osteotomy (OW-HTO) is an accepted option to treat the isolated medial compartment osteoarthritis (OA) in varus knee. Despite satisfactory outcomes were described in literature, consistent complication rate has been reported and the provided accuracy of coronal alignment correction using conventional HTO techniques falls short. Patient specific instrumentations has been introduced with the aim to reduce complications and to improve the intra-operative accuracy according to the pre-operative plan, which is responsible for the clinical result of the surgery. In this talk, an overview of the clinical results of HTO patient specific instrumentation available in literature will be performed. Moreover, preliminary intra-operative and clinical results of a new customised 3-D printed cutting guide and fixation plate for OW-HTO will be presented

A primary goal of shoulder arthroplasty is to place the components in anatomic version. However, traditional instrumentation does not accommodate glenoid wear patterns. Therefore, many investigators have attempted to use computer modeling or CT-based algorithms to create custom targeting guides to achieve this goal. There are some recent studies investigating the use of custom guides. Iannotti et al. published in JBJS-American in 2012 on the use of patient specific instrumentation. There were 31 patients included in the study. The authors found that the planning software and patient specific instrumentation were helpful overall, but particularly of benefit in patients with retroversion in excess of 16 degrees. In this group of patients, the mean deviation was 10 degrees in the standard surgical group and 1.2 degrees in the patient specific instrumentation group. Throckmorton presented a study at the AAOS in 2014 on 70 cadaveric shoulders. There was one high volume surgeon (>100 shoulder arthroplasties a year), two middle volume surgeons (20–50 shoulder arthroplasties a year), and two low volume surgeons (less than 20 shoulder arthroplasties per year). Overall, the custom guide was significantly more accurate than standard instrumentation. The custom guides were found to be especially more accurate among specimens with associated glenoid wear. There were no strong trends to indicate consistent differences between high, medium, and low volume surgeons. The authors concluded that custom guides have narrower standard deviation and fewer significant errors than standard instrumentation. Custom guides continue to evolve for use in shoulder arthroplasty including some guides that allow the surgeon to decide intra-operatively between anatomic shoulder arthroplasty and reverse arthroplasty. Additional studies will be necessary to further define the role of patient specific instrumentation in practice