Background. The National Institute of Clinical Excellence (NICE) published clinical guidelines in 2006 defining urgent referral criteria for soft tissue sarcoma to help improve the diagnostic accuracy and overall outcome. Despite these guidelines inadvertent excisions of soft tissue sarcomas continue to occur with alarming frequency potentially compromising patient outcomes. Objective. We reviewed the East Midlands Sarcoma Service experience of treating inadvertent excision of STSs and highlight the patient profile, referral pattern, subsequent management and oncological outcome associated with inadvertent resection. Methods. Patients were identified from our sarcoma database and a retrospective case note review performed. Results. Over a period of 32 months, 42 patients presented to our specialist centre after unplanned excision of soft tissue sarcomas. There were 29 men and 13 women, with a mean age at presentation of 59 years (19-90). 50% of the tumours were located in lower extremity, 33% around the trunk and 17% in the upper extremity. The unplanned surgery was most commonly from general surgeons, non-specialist orthopaedic surgeons, general practitioners followed by plastic surgeons. Re-resection was undertaken in 40 (95.2%) cases to achieve clear margins. Residual tumour was present in 74% of cases. Resected specimen histology was high grade in 90% of cases. Limb salvage surgery was not possible in 4 cases. Conclusion. Unplanned excision of sarcoma by non-oncologic surgeons remains a problem. It appears that it is equally prevalent in varied surgical community and general practitioners. Patients with soft tissue masses of unknown identity should be appropriately imaged and if the diagnosis remains unclear be transferred to centres that specialize in treating sarcomas for biopsy and adequate initial resection. Implementation of NICE guidelines and local strategies could improve the expedient management of these patients

Aims. Delays to diagnosis and management of soft tissue sarcomas are preventable but still occur. The introduction of a referral proforma to the Thames Valley Cancer Network in 2005 and National guidelines in 2006 aimed to decrease the incidence of partially and inadequately managed soft tissue sarcomas. This study aims to assess referrals for partially or inadequately managed soft tissue sarcomas and their subsequent management. Methods. A prospective analysis of all patients referred to the Oxford Sarcoma Service following inadvertent excision of a soft tissue sarcoma between January 2010 and August 2011 was carried out. Pre-operative investigation and subsequent secondary managements were recorded. Patients with a diagnosis of dermatofibrosarcoma protuberans were excluded. Results. 24 patients (17 male) with a mean age of 54.3 (6–96), representing 14.5% of all soft tissue sarcomas during this time period were followed up following incomplete or inadvertent excision. 66% were referred from secondary care, 54% had no pre-operative imaging, with the remainder having incomplete imaging. 79% of lesions were found in the extremities, with 12.5 % presenting with metastatic disease. 79% required further surgery, with 8% requiring amputation. The most common pathologies were leiomyosarcoma (29.1%), fibromyxoid sarcoma (12.5%), spindle cell sarcoma (12.5 %) and liposarcoma (8.3%). Conclusion. The consequences of incomplete initial management of soft tissue sarcomas are a cause of significant morbidity and demand on health care services. The introduction of referral guidelines has not prevented the partial management of these lesions

Background. This clinical study aims to establish the rate of operative inadvertent hypothermia (IH) in elderly hip fracture patients (>65 years old). We postulate that differences exist in risk factors and hypothesised poorer outcomes in patients with IH. Methods. A single centre, retrospective study of 929 hip fracture patients managed operatively between June 2015 and July 2017 was conducted. Patients’ demographic, anaesthetic and surgical variables were analysed together with outcomes for length of stay (LOS), 30-day re-admissions, and 30-day mortality. Results. Overall rates of IH in elderly hip fracture patients undergoing surgery were 10%, with increasing age as a risk factor (p = 0.005). There was trend towards IH in patients receiving sliding hip screw (SHS) (p = 0.079). No difference in LOS was observed between IH and normothermic patients (8.9 ± 7.1 versus 8.6 ± 4.9, p= 0.51). 30-day re-admissions were 18.5% for IH patients versus 7.8% in normothermic patients (p<0.001). There was a trend towards a higher 30-day mortality (p = 0.089), and a significantly higher mortality in IH patients undergoing SHS (p = 0.014). Conclusion. Rates of IH are high in operatively managed hip fracture patients. IH is significantly associated with a higher 30-day readmission rate with a trend towards higher 30-day mortality. This study mandates an examination of strategies for maintaining normothermia in operatively managed elderly hip fracture patients

Aims. The aim of this study was to evaluate the surgical management and outcome of patients with an acral soft-tissue sarcoma of the hand or foot. Patients and Methods. We identified 63 patients with an acral soft-tissue sarcoma who presented to our tertiary referral sarcoma service between 2000 and 2016. There were 35 men and 28 women with a mean age of 49 years (. sd. 21). Of the 63 sarcomas, 27 were in the hands and 36 in the feet. The commonest subtypes were epithelioid sarcoma in the hand (n = 8) and synovial sarcoma in the foot (n = 11). Results. In 41 patients (65%), the tumour measured less than 5 cm in its largest dimension (median size 3 cm (٢ to ٦)); 27 patients (43%) were diagnosed after inadvertent excision prior to their referral to the specialist sarcoma unit. After biopsy and staging, primary surgical intervention at the sarcoma unit was excision and limb salvage in 43 (68%), partial (digit or ray) amputation in 14 (22%), and more proximal amputation in six (10%). At final follow up, local recurrence had been treated by one partial amputation and six amputations, resulting in a partial amputation rate of 24% and a proximal amputation rate of 19%. The five-year survival rate was 82%. Patients who underwent inadvertent excision showed no statistically significant difference in survival or local recurrence, but were more likely to undergo amputation (p = 0.008). Large tumour size (> 5 cm) was associated with lower survival (p = 0.04) and a higher risk of local recurrence (p = ٠.٠٠٩). Conclusion. Most acral soft-tissue sarcomas measure less than 5 cm at presentation, indicating that while size can be a useful prognostic factor, it should not be used as a diagnostic threshold for referral. Increased tumour size is associated with a higher rate of local recurrence and reduced survival. Sarcoma excision with limb preservation does not result in an increased risk of local recurrence. Cite this article: Bone Joint J 2018;100-B:1518–23

Aims

We wished to quantify the extent of soft-tissue damage sustained during minimally invasive total hip arthroplasty through the direct anterior (DA) and direct superior (DS) approaches.

Bone sarcomas are rare cancers and orthopaedic surgeons come across them infrequently, sometimes unexpectedly during surgical procedures. We investigated the outcomes of patients who underwent a surgical procedure where sarcomas were found unexpectedly and were subsequently referred to our unit for treatment. We identified 95 patients (44 intra-lesional excisions, 35 fracture fixations, 16 joint replacements) with mean age of 48 years (11 to 83); 60% were males (n = 57). Local recurrence arose in 40% who underwent limb salvage surgery versus 12% who had an amputation. Despite achieving local control, overall survival was worse for patients treated with amputation rather than limb salvage (54% vs 75% five-year survival). Factors that negatively influenced survival were invasive primary surgery (fracture fixation, joint replacement), a delay of greater than two months until referral to our oncology service, and high-grade tumours. Survival in these circumstances depends mostly on factors that are determined prior to definitive treatment by a tertiary orthopaedic oncology unit. Limb salvage in this group of patients is associated with a higher rate of inadequate marginal surgery and, consequently, higher local recurrence rates than amputation, but should still be attempted whenever possible, as local control is not the primary determinant of survival.

Cite this article: Bone Joint J 2014;96-B:665–72.

Aims. Inadvertent soft tissue damage caused by the oscillating saw during total knee arthroplasty (TKA) occurs when the sawblade passes beyond the bony boundaries into the soft tissue. The primary objective of this study is to assess the risk of inadvertent soft tissue damage during jig-based TKA by evaluating the excursion of the oscillating saw past the bony boundaries. The second objective is the investigation of the relation between this excursion and the surgeon’s experience level. Methods. A conventional jig-based TKA procedure with medial parapatellar approach was performed on 12 cadaveric knees by three experienced surgeons and three residents. During the proximal tibial resection, the motion of the oscillating saw with respect to the tibia was recorded. The distance of the outer point of this cutting portion to the edge of the bone was defined as the excursion of the oscillating saw. The excursion of the sawblade was evaluated in six zones containing the following structures: medial collateral ligament (MCL), posteromedial corner (PMC), iliotibial band (ITB), lateral collateral ligament (LCL), popliteus tendon (PopT), and neurovascular bundle (NVB). Results. The mean 75. th. percentile value of the excursion of all cases was mean 2.8 mm (SD 2.9) for the MCL zone, mean 4.8 mm (SD 5.9) for the PMC zone, mean 3.4 mm (SD 2.0) for the ITB zone, mean 6.3 mm (SD 4.8) for the LCL zone, mean 4.9 mm (SD 5.7) for the PopT zone, and mean 6.1 mm (SD 3.9) for the NVB zone. Experienced surgeons had a significantly lower excursion than residents. Conclusion. This study showed that the oscillating saw significantly passes the edge of the bone during the tibial resection in TKA, even in experienced hands. While reported neurovascular complications in TKA are rare, direct injury to the capsule and stabilizing structures around the knee is a consequence of the use of a hand-held oscillating saw when making the tibial cut. Cite this article: Bone Joint J 2020;102-B(10):1324–1330

Aims. Urgent referral to a specialist centre for patients with a soft-tissue sarcoma (STS) has been recommended by the National Institute for Health and Care Excellence (NICE) in the UK since 2006. However, the impact of this recommendation on the prognosis for these patients remains unclear. We aimed to determine the impact of the NICE guidelines on the disease-specific survival (DSS) of patients with an STS. Methods. A total of 2,427 patients with an STS referred to a supraregional centre in the ten-year periods before (n = 1,386) and after (n = 1,041) the issue of the NICE guidelines were evaluated. Results. The mean size of the tumour was significantly smaller at the time of diagnosis (10.3 cm (SD 6.5) vs 9.1 cm (SD 6.2); p < 0.001) and the number of patients who had undergone an inadvertent excision significantly decreased (28% (n = 389) vs 20% (n = 204); p < 0.001) following the introduction of the NICE guidelines. The five-year DSS was 63% in the pre-NICE and 71% in post-NICE groups (p < 0.001). The improved survival was more significant for those with a high-grade tumour (pre-NICE, 48%; post-NICE, 68%; p < 0.001). In those with a high-grade tumour, the mean size of the tumour (11.6 cm (SD 6.2) vs 9.6 cm (SD 5.8); p < 0.001) and the number of patients with metastasis at the time of diagnosis (15% (n = 124 vs 10% (n = 80); p = 0.007) significantly decreased in the post-NICE group. Conclusion. An improvement in survival was seen after the introduction of the NICE guidelines, especially in patients with a high-grade STS. More patients were referred at an earlier stage, indicating a clearer pathway after the issue of national policy for the management of STSs in the UK. Cite this article: Bone Joint J 2021;103-B(3):569–577

Lisfranc injuries account for 0.2% of all fractures and have been linked to poorer functional outcomes, in particular resulting in post-traumatic arthritis, midfoot collapse and chronic pain. This study assesses the longitudinal functional outcomes in patients with low and high energy Lisfranc injuries treated both operatively and non-operatively. Patients above 16 years with Lisfranc injuries from January 2008 and December 2017 were identified through the Victorian Orthopaedic Trauma Outcomes (VOTOR) registry. Follow-up performed at 6, 12 and 24 months through telephone interviews with response rate of 86.1%, 84.2% and 76.2% respectively. Longitudinal functional outcome data using Global Outcome Assessment, EQ-5D-5L, numerical pain scale, Short-Form 12, the WHO Disability Assessment Schedule and return to work status were collected. Univariate analysis was performed and variables showing a significant difference between groups (p < 0.25) were analysed with multivariable mixed effects regression model. 745 patients included in this retrospective cohort study. At 24 months, both the operative and non-operative groups demonstrated similar functional outcomes trending towards an improvement. Mixed effect regression models for the EQ items for mobility (OR 1.80, CI 0.91 – 3.57), self-care (OR 1.95, 95% CI 1.09-3.49), usual activities (OR 1.10, 95% CI 0.99-1.03), pain (OR 1.07, 95% CI 0.61-1.89), anxiety (OR 1.29, 95% CI 0.72-2.34) and pain scale (OR 1.07, 95% CI 0.51 – 2.22) and return to work (OR 1.28, 95% CI 0.56-2.91) between groups were very similar and not statistically significantly different. We concluded that there was no statistically significant difference between operative and non-operative patients with low and high energy Lisfranc injuries. Current clinical practices in Lisfranc injury management are appropriate and not inadvertently causing any further harm to patients. Future research comparing fracture patterns, fixation types and corresponding functional outcomes can help determine gold standard Lisfranc injury management

Timely and competent treatment of paediatric fractures is paramount to a healthy future working population. Anecdotal evidence suggests that children travel greater distances to obtain care compared to adults causing economic and geographic inequities. This study aims to qualify the informal regionalization of children's fracture care in Ontario. The results could inform future policy on resource distribution and planning of the provincial health care system. A retrospective cohort study was conducted examining two of the most common paediatric orthopaedic traumatic injuries, femoral shaft and supracondylar humerus fractures (SCH), in parallel over the last 10 years (2010-2020) using multiple linked administrative databases housed at the Institute for Clinical Evaluative Sciences (ICES) in Toronto, Ontario. We compared the distance travelled by these pediatric cohorts to clinically equivalent adult fracture patterns (distal radius fracture (DR) and femoral shaft fracture). Patient cohorts were identified based on treatment codes and distances were calculated from a centroid of patient home forward sortation area to hospital location. Demographics, hospital type, and closest hospital to patient were also recorded. For common upper extremity fracture care, 84% of children underwent surgery at specialized centers which required significant travel (44km). Conversely, 67% of adults were treated locally, travelling a mean of 23km. Similarly, two-thirds of adult femoral shaft fractures were treated locally (mean travel distance of 30km) while most children (84%) with femoral shaft fractures travelled an average of 63km to specialized centers. Children who live in rural areas travel on average 51km more than their adult rural-residing counterparts for all fracture care. Four institutions provide over 75% of the fracture care for children, whereas 22 institutions distribute the same case volume in adults.?. Adult fracture care naturally self-organizes with proportionate distribution without policy-directed systemization. There is an unplanned concentration of pediatric fracture care to specialized centers in Ontario placing undue burden on pediatric patients and inadvertently stresses the surgical resources in a small handful of hospitals. In contrast, adult fracture care naturally self-organizes with proportionate distribution without policy-directed systemization. Patient care equity and appropriate resource allocation cannot be achieved without appropriate systemization of pediatric fracture care

Aims. Perthes’ disease (PD) often results in femoral head deformity and leg length discrepancy (LLD). Our objective was to analyze femoral morphology in PD patients at skeletal maturity to assess where the LLD originates, and evaluate the effect of contralateral epiphysiodesis for length equalization on proximal and subtrochanteric femoral lengths. Methods. All patients treated for PD in our institution between January 2013 and June 2020 were reviewed retrospectively. Patients with unilateral PD, LLD of ≥ 5 mm, and long-leg standing radiographs at skeletal maturity were included. Total leg length, femoral and tibial length, articulotrochanteric distance (ATD), and subtrochanteric femoral length were compared between PD side and the unaffected side. Furthermore, we compared leg length measurements between patients who did and who did not have a contralateral epiphysiodesis. Results. Overall, 79 patients were included, of whom 21 underwent contralateral epiphysiodesis for leg length correction. In the complete cohort, the mean LLD was 1.8 cm (95% confidence interval (CI) 1.5 to 2.0), mean ATD difference was 1.8 cm (95% CI -2.1 to -1.9), and mean subtrochanteric difference was -0.2 cm (95% CI -0.4 to 0.1). In the epiphysiodesis group, the mean LLD before epiphysiodesis was 2.7 cm (95% CI 1.3 to 3.4) and 1.3 cm (95% CI -0.5 to 3.8) at skeletal maturity. In the nonepiphysiodesis group the mean LLD was 2.0 cm (95% CI 0.5 to 5.1; p = 0.016). The subtrochanteric region on the PD side was significantly longer at skeletal maturity in the epiphysiodesis group compared to the nonepiphysiodesis group (-1.0 cm (95% CI -2.4 to 0.6) vs 0.1 cm (95% CI -1.0 to 2.1); p < 0.001). Conclusion. This study demonstrates that LLD after PD originates from the proximal segment only. In patients who had contralateral epiphysiodesis to balance leg length, this is achieved by creating a difference in subtrochanteric length. Arthroplasty surgeons need to be aware that shortening of the proximal femur segment in PD patients may be misleading, as the ipsilateral subtrochanteric length in these patients can be longer. Therefore, we strongly advise long-leg standing films for THA planning in PD patients in order to avoid inadvertently lengthening the limb. Cite this article: Bone Joint J 2021;103-B(11):1736–1741

Aims. The risk to patients and healthcare workers of resuming elective orthopaedic surgery following the peak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been difficult to quantify. This has prompted governing bodies to adopt a cautious approach that may be impractical and financially unsustainable. The lack of evidence has made it impossible for surgeons to give patients an informed perspective of the consequences of elective surgery in the presence of SARS-CoV-2. This study aims to determine, for the UK population, the probability of a patient being admitted with an undetected SARS-CoV-2 infection and their resulting risk of death; taking into consideration the current disease prevalence, reverse transcription-polymerase chain reaction (RT-PCR) testing, and preassessment pathway. Methods. The probability of SARS-CoV-2 infection with a false negative test was calculated using a lower-end RT-PCR sensitivity of 71%, specificity of 95%, and the UK disease prevalence of 0.24% reported in May 2020. Subsequently, a case fatality rate of 20.5% was applied as a worst-case scenario. Results. The probability of SARS-CoV-2 infection with a false negative preoperative test was 0.07% (around 1 in 1,400). The risk of a patient with an undetected infection being admitted for surgery and subsequently dying from the coronavirus disease 2019 (COVID-19) is estimated at approximately 1 in 7,000. However, if an estimate of the current global infection fatality rate (1.04%) is applied, the risk of death would be around 1 in 140,000, at most. This calculation does not take into account the risk of nosocomial infection. Conversely, it does not factor in that patients will also be clinically assessed and asked to self-isolate prior to surgery. Conclusion. Our estimation suggests that the risk of patients being inadvertently admitted with an undetected SARS-CoV-2 infection for elective orthopaedic surgery is relatively low. Accordingly, the risk of death following elective orthopaedic surgery is low, even when applying the worst-case fatality rate. Cite this article: Bone Joint J 2020;102-B(9):1256–1260

Myxofibrosarcoma (MFS) is the second most common subtype of soft tissue sarcoma (STS) and is associated with a high rate of local recurrence after resection. These tumours frequently present with peri-lesional edema, termed “tumour tails” on staging MRI scans [1]. Tumour tails(TT) may contain satellite neoplastic cells or can represent benign reactive edema. There are no clear radiological features to distinguish malignant from reactive peri-lesional edema which limits accurate surgical planning, resulting in either high rates of inadvertently positive resection margins and local recurrences or overly-aggressive resections which negatively impact function and increase morbidity [2]. The objective of this pilot study was to prospectively study a cohort of MFS patients with TTs in an attempt to identify radiological features that predict which type of edema is malignant and requires resection together with the main tumour mass. Patients diagnosed with MFS on biopsy at an orthopaedic oncology referral centre between January 1-December 31 2018 who also had TTs on staging MRI scans were prospectively recruited for the study. Tumours were treated with wide surgical excision, including the TTs, and (neo)adjuvant radiotherapy as per institutional protocol. Staging MRI scans were reviewed in a blinded fashion by two musculoskeletal radiologists to distinguish malignant from reactive TTs. The main tumour mass underwent standard histological evaluation while the regions encompassing the TTs were photographed and sectioned into grids. Each tissue section was examined histologically for the presence of satellite neoplastic cells based on morphological criteria. Radiological and histological findings were compared. Six patients met the inclusion criteria and underwent analysis. All tumours were located in the extremities and were deep to fascia. Mean age at presentation was 67 years (range 51 – 85), with a male:female ratio of 4:2. All patients received radiotherapy (50 Gy), either pre- (n=4) or post-operatively (n=2) based on multidisciplinary tumor board discussion or enrolment in a prospective clinical trial. Radiologically, TTs were labelled as malignant in four patients (66.7%) and as benign TTs in two others. The tails were recognised to be malignant due to the differing signal characteristics to reactive edema on mixed MRI sequences. The radiological evaluation correlated exactly with histological analysis, as satellite neoplastic cells were identified microscopically in the same four cases in which the TTs were designated to be malignant by MRI (specificity&sensitivity=100%). Surgical resection margins were microscopically positive in 50% of cases in the TTs themselves, and 75% of cases in which TTs were designated as malignant on staging MRI. “The malignant nature of peri-lesional edema in MFS, also known as the TT, was accurately predicted in this small pilot study based on specific radiological features which correlated exactly with histologic identification of isolated tumor cells. These findings validate development of a larger prospective study to recruit additional patients with tumor tails beyond just MFS, in order to more robustly study the correlation between the MRI appearance and histological distribution of satellite sarcoma cells in peri-lesional edema in STS. We are already recruiting to this expanded radiological-histological investigation including evaluation of additional novel MRI sequences

Introduction. Primary soft tissue sarcomas of the extremities are uncommon. Many such lesions will present to specialists in other clinics such as specialist Hand or Foot and Ankle clinics. Many are of a small size at presentation and may appear to be alternate, more common pathology. Methods. We collected data from all those patients with acral soft tissues sarcomas and referred to the Oxford Sarcoma Service, Nuffield Orthopaedic Centre, Oxford over a thirteen year period from 1997 – 2010. Data were collected regarding the primary suspected diagnosis, the final diagnosis, the referral route and whether patients had undergone previous inadvertent excision. Results. 38 patients were treated (24 foot, 14 hand tumours). The commonest histological subtype was synovial sarcoma in the foot group, and leiomyosarcoma in the hand group. 25 of the 38 patients had a lesion of less than 5cm at presentation. For those patients in whom a wide excision was performed 50% underwent complex plastic surgical reconstruction. Discussion. This study shows that 30% of patients with acral tumours required further surgery due to previous inadequate/inadvertent excision. 5cm as a benchmark for specialist referral should not be applied to lesions in the hand or feet and we recommend the use of the “marble rule” i.e. any lesion the size of a marble should be referred urgently and no patient should undergo surgery without imaging

Summary. A rotational limit for screw insertion may improve screw purchase and plate compression by reducing stripping, as compared to a torque based limit. Introduction. Over-tightening screws results in inadvertent stripping of 20% of cortical bone screws. The current method of “two-fingers tight” to insert screws relies on the surgeon receiving torque feedback. Torque, however, can be affected by screw pitch, bone density and bone-thread friction. An alternative method of tightening screws is the “turn-of-the-nut” model, commonly used in engineering applications. In the “turn-of-the-nut” method, nuts used to fasten a joint are rotated a specific amount in order to achieve a pre-specified bolt tension. When applied to orthopaedics, bone assumes the role of the nut and the screw is the bolt. The screw is turned a set angular rotation that is independent of torque feedback. Potentially the “turn-of-the-nut” method provides an easier way of screw insertion that might lessen inadvertent screw stripping. The purpose of the current study was to use the “turn-of-the-nut” method to determine the angular rotation that results in peak plate compression and peak screw pullout force. Methods. Three pairs of human humeri in each of three groups (osteopenic, osteoporotic, and normal) underwent plate compression and pullout protocols. For plate compression, 3.5-mm screws were tightened into strain gauge instrumented plate until screw stripping occurred. Insertion torque, plate compression, and screw rotation were measured. For pullout, 3.5-mm screws were inserted until the head contacted the plate, additionally rotated (90, 180, 270, or 360 degrees), and then pulled out. A generalised linear and latent mixed model was used to check for significant associations (P < 0.05). Results. Mean (95% CI) peak plate compression occurred at 286 degrees (range, 261 – 311 degrees) beyond screw seating. Plate compression significantly increased at 90 to 135 degrees but not after 180 degrees. At 270 degrees, 39% of the screws had already reached their peak ability to compress. Peak screw torque lagged behind peak plate compression by 31 ± 50 degrees, and in seeking peak screw torque, a loss of 104 ± 115 N in plate compression resulted. Screw pullout force was greatest at 90 degrees, but it was not significantly different from that of the other angle groups. Conclusions. Screw rotation at 180 degrees provides plate compression and pullout strength statistically similar to those at greater rotations but without the loss of purchase associated with greater rotations

Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the uncommon tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These can result in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. Two year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the using the robot to complete the procedure. Report the clinical outcomes with robotic total knee replacement at or beyond two years to demonstrate no delayed effect on expected outcome. Methods. The initial consecutive series of 65 Triathlon. TM. total knee replacements using a semi-active haptic guided system that were performed after commercialization that would be eligible for two year follow-up were reviewed. Pre-operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament, patellar tendon, or a neurovascular structure from the cutting tool. Operative notes were also reviewed to determine if the robotic procedure was partially or completely aborted due to any issue. Knee Society Knee Scores (KS-KS) and Functional Scores (KS-FS) were recorded from pre-operative and yearly. Any complications were recorded. Results. 40 cases had two year follow-up. The average follow-up for this series was 1.51 years. No cases were unable to be completed robotically. No case had evidence for acute or delayed injury to the medial collateral ligament, patellar tendon, or neurovascular structure. The only complication was a revision total knee for tibial component loosening after a fall induced periprosthetic tibial fracture. Average pre-operative KS-KS and KS-FS improved from 46.9 and 52.1 to 99.2 and 88.6 at one year follow-up, 100.5 and 86.9 at two year follow-up. Conclusions. A semi-active haptic guided robotic system is a safe and reliable method to perform total knee replacement surgery. This series of initial robotic arm assisted surgery had no intraoperative or delayed soft tissue injuries. Preliminary short-term outcomes at up to two years show excellent outcomes

This study investigated the anatomical relationship between the clavicle and its adjacent vascular structures, in order to define safe zones, in terms of distance and direction, for drilling of the clavicle during osteosynthesis using a plate and screws following a fracture. We used reconstructed three-dimensional CT arteriograms of the head, neck and shoulder region. The results have enabled us to divide the clavicle into three zones based on the proximity and relationship of the vascular structures adjacent to it. The results show that at the medial end of the clavicle the subclavian vessels are situated behind it, with the vein intimately related to it. In some scans the vein was opposed to the posterior cortex of the clavicle. At the middle one-third of the clavicle the artery and vein are a mean of 17.02 mm (5.4 to 26.8) and 12.45 mm (5 to 26.1) from the clavicle, respectively, and at a mean angle of 50° (12 to 80) and 70° (38 to 100), respectively, to the horizontal. At the lateral end of the clavicle the artery and vein are at mean distances of 63.4 mm (46.8 to 96.5) and 75.67 mm (50 to 109), respectively. An appreciation of the information gathered from this study will help minimise the risk of inadvertent iatrogenic vascular injury during plating of the clavicle

Introduction. Patient Specific Guides (PSGs) are used to increase the accuracy of arthroplasty. PSGs achieve this by incorporating geometry that fits in one unique position and orientation on a patient's bone. Sufficient docking rigidity ensures PSGs do not shift before being fixed by pins. Despite the importance of PSG docking rigidity, minimal research has been conducted on this issue. This study aims to determine whether commercially available PSGs, in their equilibrium position, provide sufficient stability for reliable surgical use. Materials and Methods. A commercially available PSG (Glenoid PSG, BLUEPRINT™, Wright Medical) was analyzed and tested in this study; the mechanical performance of this guide was assessed using a custom testing apparatus mounted to a universal testing machine (UTM) (MTI-10k, Materials Testing Inc), assembled with a high-precision load cell (MiniDyn Type 9256C, Kistler). The apparatus accepts an additively manufactured glenoid surrogate and was designed to transform vertical crosshead forces from the UTM into PSG-applied forces transverse to the glenoid plane along anterior-posterior and superior-inferior axes and PSG-applied torques about lateral, anterior, and superior axes. Three trials were recorded for each force and torque application. Prior to each test, the glenoid surrogate and PSG were articulated together with a constant 27N compressive force — equivalent to the normal force exerted by a surgeon using the guide — applied using springs. Forces were recorded when the guide was displaced 2mm by transverse loads or 5° by torque application; if the guide visibly dislodged from the glenoid surrogate before either criterion was met, force was recorded at the time of dislodgement. If no PSG movement occurred, testing ceased at 75N or 1.19N⋅m, depending on the test type. Results. The lowest and highest torques to displace the PSG by 5° were around the lateral (−0.08±0.02 N⋅m) and superior axes (0.87±0.23 N⋅m), respectively. The lowest and highest forces to displace the PSG by 2mm were along the inferior (31.77± 6.30N) and posterior axes (64.80±0.79N), respectively. Although it yielded at a higher torque than about the lateral axis, CCW rotation about the posterior axis produced the earliest PSG dislodgement at 3.76° while the PSG dislodged after only 1.05mm in the anterior direction. Discussion. The above results demonstrate that the tested PSG design produces similar docking rigidity for all tested rotations except rotations about the lateral axis, which provided 4 times less stability than the next lowest result. This indicates that the PSG may not provide sufficient resistance in this direction to prevent inadvertent mal-rotation. The relatively low rigidity in anterior and superior translation indicate that this PSG design may be prone to mal-positioning errors in these directions. With these data in mind, PSG docking rigidity is not equal in all loading directions which could play a role in the clinical accuracy. Furthermore, this indicates that a systematic, objective method for PSG design optimization may be warranted. For any figures or tables, please contact authors directly

Two stage exchange has been the gold standard in North America for the treatment of infected knee replacements. The choice of static vs. articulated spacers has been debated for a number of years. At our institution our choice of spacer for 2 stage exchanges is an articulated spacer. This allows motion between stages which facilitates recovery, and makes the second stage technically easier. In a study from our institution we followed 115 infected TKAs treated with the PROSTALAC articulated spacer for 5–9 years. Success for eradication of infection was 88%. With a repeat 2 stage, overall infection control was 98%. In addition, we compared functional outcomes to a group of aseptic knee revisions and found no difference in functional outcomes with standard quality of life outcome scores. While the articulated spacer was our treatment of choice in 2 stage exchange around 2012, the company that manufactured the PROSTALAC knee components ceased to manufacture them. At that time, based on the work of 2 previous studies (Hofmann, Lee), we continued to use articulated spacers. However, this was now the so-called Hofmann technique with a new standard femoral component with an all polyethylene tibia. The only difference from a standard knee revision was no stems and the utilization of high dose antibiotics. We also followed the principles from Europe of one stage exchange, such as wide debridement and soaking in dilute betadine for 15 minutes. More recently as of Sept 2015 we have used an all polyethylene tibia with a keel. The hope being that this will give a more stable tibia than previous and perhaps make a second stage unnecessary. Our first case was September 2015. The intention was not to do a second stage if the infection was eradicated and the patient had good pain relief and function. To date we have implanted 28 of these and in 80% of cases we have not had to do a second stage revision. Further study will reveal where this inadvertent one stage fits in our practi

Introduction: The curing of polymethylmethacrylate cement is an exothermic reaction, with temperatures reaching 80oC. Thus contact with cement can result in thermal injury. During orthopaedic procedures bone cement may be inadvertently left lying on surgical drapes. This study aims to investigate the effect of drapes on the contact temperature of such cement. Methods: The experiment was carried out in an orthopaedic theatre with a constant temperature and humidity. Polymethylmethacrylate cement was prepared and pieces of cement of a specific size were investigated. Experiment one measured the contact temperature of curing cement in isolation. Experiment two and three investigated the effect of one and two layers of surgical drape respectively on contact temperature. Results: The mean maximum temperature reached in experiments one, two and three was 75oC, 71oC and 69oC respectively. The maximum temperature was reached quickest in experiment three. In considering the time period that the contact temperature remained above 40oC this was longest in experiment three at 750s followed by experiment 2 and then experiment 1 at 525s and 330s respectively. Contact temperature graphs for each experiment have been plotted in figure.1. Discussion: One might think that drapes provide a protective barrier between a patient’s skin and bone cement, however this is incorrect. The drapes insulate the exothermic reaction of curing bone cement which tends to accelerate the reaction. Furthermore the insulating effect of drapes causes curing bone cement to lose heat at a slower rate resulting in the contact temperature remaining above 40oC for longer; this increases the potential for thermal injury. This study demonstrates that a specific effort should be made to ensure bone cement is not inadvertently left lying on surgical drapes