Co-Cr-Mo alloys are widely used for biomedical implant materials such as artificial hip and knee joints owing to their excellent corrosion and wear resistance as well as higher strengthening properties. However, the alloys exhibits sever brittle nature under an as-cast condition. It is generally recognized that refinement of the grain size of the metallic materials by means of hot-forging processes is an effective methodology to strengthen the alloy. Dynamic recrystallization (DRX) is an effective metallurgical process for grain refinement during hot deformation. However, there are few studies on the hot deformation behavior of Co-Cr-Mo alloy, especially grain refinement through DRX. In the present study, DRX and grain refinement during hot deformation of Co-29Cr-6Mo alloy has been investigated under various conditions such as deformation temperature and strain rate. Although at strain of 5% hot deformed microstructure maintains the original grains, the grain size decreases with increasing the strain and exhibits the average grain size of approximately 2μm at strain of 60%. Ultra fine grained microstructure with the grain size of approximately 0.5 μm was obtained under deformation at a 1323 K at a strain rate of 0.1s. -1. The original grains are broken up into different grains due to the new boundary formation not only near the initial boundaries but also in the interior of the grains at large strain. This grain fragmentation without bulging in the course of hot deformation is associated with considerably low stacking fault energy (SFE) of the Co-29Cr-6Mo alloy even at the deformation temperatures

Introduction. The reconstruction of segmental long bone defects remains one of the holy grails of orthopaedic surgery. The optimal treatment of which remains a topic of great debate. This study aimed to evaluate the outcomes following the management of critical-sized bone defects using a classification-based treatment algorithm. Materials & Methods. A retrospective review of all patients undergoing treatment for segmental diaphyseal defects of long bones at a tertiary-level limb reconstruction unit was performed. The management of the bone defect was standardised as per the classification by Ferreira and Tanwar (2020). Results. A total of 96 patients (mean age 39.8, SD 15.2) with a minimum six months follow-up were included. Most bone defects were the result of open fractures (75/96) with 67% associated with Gustilo-Anderson IIIB injuries. There was a statistical difference in the likelihood of union between treatment strategies with more than 90% of cases undergoing acute shortening and bone transport achieving union and only 72% of cases undergoing the induced membrane technique consolidating (p=0.049). Of those defects that consolidated, there was no difference in the time to bone union between strategies (p=0.308) with an overall median time to union 8.33 months (95% CI 7.4 — 9.2 months). The induced membrane technique was associated with a 40% risk of sepsis. Conclusions. This study reported the outcomes of a standardised approach to the management of critical-sized bone defects. Whilst overall results were supportive of this approach, the outcomes associated with the induced membrane technique require further refinement of its indications in the management of critical-sized bone defects

INTRODUCTION. Simulation plays an important role in surgical education and the ability to perfect surgical performance. Simulation can be enhanced by adding various layers of realism to the experience. Haptic feedback enhances the simulation experience by providing tactile responses and virtual reality imagery provides an immersive experience and allows for greater appreciation of three-dimensional structures. In this study, we present a proof-of-concept haptic simulator to replicate key steps of a cervical laminoplasty procedure. The technology uses affordable components and is easily modifiable so that it can be used from novice through to expert level. Custom models can be easily added ensuring the simulator can be used in a wide range of orthopaedic applications from baseline education through to day of surgery pre-operative simulation. METHOD. We used the Unity Game Engine, the 3D Systems “Touch” Haptic Feedback Device (HFD), and a Meta Quest VR headset. Our system uses a number of complex algorithms to track the shape and provide haptic feedback of a virtual bone model. This allows for simulation of various tools including a high-speed burr, Kerrison rongeur and intraoperative X-rays. RESULTS. Our simulator replicates the tactile sensations of bone-burring tasks. Although we focused on the cervical laminoplasty procedure, the system can load data from CT scans, enabling the simulation of multiple other procedures. The parts cost of our system, $10,000 NZD, is a fraction of the cost of traditional surgical simulators. DISCUSSION. Our simulator reduces financial barriers to accessing orthopaedic simulators. Trainees can perform hands-on practice without compromising patient safety. The immersive nature of VR, combined with realistic haptic feedback, enables trainees to develop the dexterity and three-dimensional understanding of detailed bony work. Further refinements are needed before we can perform validation studies on our system. CONCLUSIONS. We present an affordable surgical simulator capable of simulating bony surgical procedures in a VR environment using haptic feedback technology and consumer-grade components. ACKNOWLEDGEMENTS. This research was made possible by the generosity of the Wishbone Trust

The presence of metastatic bone disease (MBD) often necessitates major orthopaedic surgery. Patients will enter surgical care either through emergent or electively scheduled care pathways. Patients in a pain crisis or with an acute fracture are generally admitted via emergent care pathways whereas patients with identified high-risk bone lesions are often booked for urgent yet scheduled elective procedures. The purpose of this study is to compare the post-operative outcomes of patients who present through emergent or electively scheduled care pathways in patients in a Canadian health care system. We have conducted a retrospective, multicenter cohort study of all patients presenting for surgery for MBD of the femur, humerus, tibia or pelvis in southern Alberta between 2006 and 2021. Patients were identified by a search query of all patients with a diagnosis of metastatic cancer who underwent surgery for an impending or actual pathologic fracture in the Calgary, South and Central Alberta Zones. Subsequent chart reviews were performed. Emergent surgeries were defined by patients admitted to hospital via urgent care mechanisms and managed via unscheduled surgical bookings (“on call list”). Elective surgeries were defined by patients seen by an orthopaedic surgeon at least once prior to surgery, and booked for a scheduled urgent, yet elective procedure. Outcomes include overall survival from the time of surgery, hospital length of stay, and 30-day hospital readmission rate. We have identified 402 patients to date for inclusion. 273 patients (67.9%) underwent surgery through emergent pathways and 129 patients (32.1%) were treated through urgent, electively scheduled pathways. Lung, prostate, renal cell, and breast cancer were the most common primary malignancies and there was no significant difference in these primaries amongst the groups (p=0.06). Not surprisingly, emergent patients were more likely to be treated for a pathologic fracture (p<0.001) whereas elective patients were more likely to be treated for an impending fracture (p<0.001). Overall survival was significantly shorter in the emergent group (5.0 months, 95%CI: 4.0-6.1) compared to the elective group (14.9 months 95%CI: 10.4-24.6) [p<0.001]. Hospital length of stay was significantly longer in the emergent group (13 days, 95%CI: 12-16 versus 5 days, 95%CI: 5-7 days). There was a significantly greater rate of 30-day hospital readmission in the emergent group (13.3% versus 7.8%) [p=0.01]. Electively managed MBD has multiple benefits including longer post-operative survival, shorter length of hospital stay, and a lower rate of 30-day hospital readmission. These findings from a Canadian healthcare system demonstrate clinical value in providing elective orthopaedic care when possible for patients with MBD. Furthermore, care delivery interventions capable of decreasing the footprint of emergent surgery through enhanced screening or follow-up of patients with MBD has the potential to significantly improve clinical outcomes in this population. This is an ongoing study that will justify refinements to the current surgical care pathways for MBD in order to identify patients prior to emergent presentation. Future directions will evaluate the costs associated with each care delivery method to provide opportunity for health economic efficiencies

Aims. Orthopaedic surgeries are complex, frequently performed procedures associated with significant haemorrhage and perioperative blood transfusion. Given refinements in surgical techniques and changes to transfusion practices, we aim to describe contemporary transfusion practices in orthopaedic surgery in order to inform perioperative planning and blood banking requirements. Methods. We performed a retrospective cohort study of adult patients who underwent orthopaedic surgery at four Canadian hospitals between 2014 and 2016. We studied all patients admitted to hospital for nonarthroscopic joint surgeries, amputations, and fracture surgeries. For each surgery and surgical subgroup, we characterized the proportion of patients who received red blood cell (RBC) transfusion, the mean/median number of RBC units transfused, and exposure to platelets and plasma. Results. Of the 14,584 included patients, the most commonly performed surgeries were knee arthroplasty (24.8%), hip arthroplasty (24.6%), and hip fracture surgery (17.4%). A total of 10.3% of patients received RBC transfusion; the proportion of patients receiving RBC transfusions varied widely based on the surgical subgroup (0.0% to 33.1%). Primary knee arthroplasty and hip arthroplasty, the two most common surgeries, were associated with in-hospital transfusion frequencies of 2.8% and 4.5%, respectively. RBC transfusion occurred in 25.0% of hip fracture surgeries, accounting for the greatest total number of RBC units transfused in our cohort (38.0% of all transfused RBC units). Platelet and plasma transfusions were uncommon. Conclusion. Orthopaedic surgeries were associated with variable rates of transfusion. The rate of RBC transfusion is highly dependent on the surgery type. Identifying surgeries with the highest transfusion rates, and further evaluation of factors that contribute to transfusion in identified at-risk populations, can serve to inform perioperative planning and blood bank requirements, and facilitate pre-emptive transfusion mitigation strategies. Cite this article: Bone Jt Open 2021;2(10):850–857

Length of hospital stay has been decreased to the point where the next logical progression in arthroplasty surgery is outpatient arthroplasty procedures. This trend has already happened for procedures formerly regarded as “inpatient” procedures such as upper extremity surgery, arthroscopy, anterior cruciate ligament reconstruction, foot and ankle procedures, and rotator cuff repair. Refinement of surgical techniques, anesthesia protocols, and patient selection has facilitated this transformation. Today, hip, knee and shoulder arthroplasty can be performed safely as outpatient procedures by implementing surgical and protocol refinements. Understanding and addressing, safely, the reasons that surgeons and patients believe they “need” a hospital admission is the cornerstone to outpatient arthroplasty. This program can be highly beneficial to patients, surgeons, anesthesia, ambulatory surgery centers, and payors as arthroplasty procedures shift to the outpatient space. It will always cost more to perform these procedures in hospitals therefore opening up significant opportunities. The less efficiently run hospital in-patient setting demands over-treatment of each patient to fit him or her into the mold of inpatient surgery. Patient satisfaction is very high in the outpatient setting. Patients can recover in their own home with reduced inpatient services and by utilizing outpatient physical therapy. The surgeon efficiently controls the local environment, and thus the overall patient experience and satisfaction are improved in the outpatient setting. The surgeon's role changes from commoditised technician in the hospital setting to coordinator of the entire care experience including pre-operative care, imaging, anesthesia, peri-operative care mapping, post-operative care, and enhanced coordination with therapy providers. An outpatient arthroplasty program involves multiple individuals and specialised protocols for pre-operative, peri-operative, and post-operative care. These include patient selection and education, anesthesia and analgesia, and minimally invasive surgical techniques. By implementing these protocols and a minimally invasive Watson-Jones approach, one study has reported 77% utilization of outpatient THA, 99% success with day of surgery discharge, and a 1% readmission or complication rate. Outpatient arthroplasty is safe, it's better for us and our patients, and it is here now. In an outpatient environment the surgeon actually spends more time with the patients and family in a friendly environment. Patients feel safe and well cared for, and are highly satisfied with their arthroplasty experience. In a typical day a surgeon can perform 6–8 outpatient arthroplasty procedures with multiple interactions with each patient and their family throughout the day. Avoidance of narcotics with peripheral and local blocks will increase the eligibility for outpatient surgery and decrease the need for overnight hospitalization. The singular focus on the patient and the avoidance of over-treatment will become the standard of care for total hip and total knee arthroplasty in much the same way as for other procedures once deemed “inpatient” surgeries

Background. The advent of value-based conscientiousness and rapid-recovery discharge pathways presents surgeons, hospitals, and payers with the challenge of providing the same total hip arthroplasty episode of care in the safest and most economic fashion for the same fee, despite patient differences. Various predictive analytic techniques have been applied to medical risk models, such as sepsis risk scores, but none have been applied or validated to the elective primary total hip arthroplasty (THA) setting for key payment-based metrics. The objective of this study was to develop and validate a predictive machine learning model using preoperative patient demographics for length of stay (LOS) after primary THA as the first step in identifying a patient-specific payment model (PSPM). Methods. Using 229,945 patients undergoing primary THA for osteoarthritis from an administrative database between 2009– 16, we created a naïve Bayesian model to forecast LOS after primary THA using a 3:2 split in which 60% of the available patient data “built” the algorithm and the remaining 40% of patients were used for “testing.” This process was iterated five times for algorithm refinement, and model performance was determined using the area under the receiver operating characteristic curve (AUC), percent accuracy, and positive predictive value. LOS was either grouped as 1–5 days or greater than 5 days. Results. The machine learning model algorithm required age, race, gender, and two comorbidity scores (“risk of illness” and “risk of morbidity”) to demonstrate excellent validity, reliability, and responsiveness with an AUC of 0.87 after five iterations. Hospital stays of greater than 5 days for THA were most associated with increased risk of illness and risk of comorbidity scores during admission compared to 1–5 days of stay. Conclusions. Our machine learning model derived from administrative big data demonstrated excellent validity, reliability, and responsiveness after primary THA while accurately predicting LOS and identifying two comorbidity scores as key value-based metrics. Predictive data has the potential to engender a risk-based PSPM prior to primary THA and other elective orthopaedic procedures

Introduction. Titanium and its alloys are attractive biomaterials attributable to their desirable corrosion, mechanical, biocompatibility and osseointegration properties. Ti6Al4V alloy in particular remains a prominent biomaterial used in Total Hip Arthroplasty (THA) today. This is partly due to biocompatibility and stress shielding issues with CoCrMo alloys, resulting in its increasing side-lining from the THA construct. For several decades now, research efforts have been dedicated to understanding wear, corrosion and surface degradation processes in implant materials. Only recently have researchers shown interest in understanding the subsurface implications of fretting and the role it plays on implant fracture. The purpose of this study was to utilise advanced microscopy and spectroscopy techniques to characterise fretting-induced subsurface transformations in Ti6Al4V. This makes mapping specific regions that are most prone to wear and fatigue failures at the modular taper interface of THA probable. Thus, informing a proactive approach to component design and material selection. Method. A ball-on-flat configuration was utilised in this study to achieve a Hertzian point contact for a CoCrMo – Ti6Al4V material combination. Four fretting displacement amplitudes were assessed: ±10, ±25, ±50 and ±150 µm. An initial contact pressure of 1 GPa was used for all fretting tests in this study and each fretting test lasted 6000 cycles at a frequency of 1 Hz. The simulated physiological solution consisted of Foetal Bovine Serum (FBS) diluted to 25% with Phosphate Buffered Saline (PBS) and 0.03% Sodium Azide (SA) balance. The temperature was kept at ∼37°C. Subsurface transformations in the Ti6Al4V alloy was characterised using the Transmission Electron Microscopy (TEM) to obtain high resolution micrographs. The samples were prepared using a FIB-SEM. Bright-field, dark-field and selected area electron diffraction (SAED) patterns were all captured using a scanning TEM (STEM) and Energy Dispersed X-Ray spectroscopy (EDX) mapping was carried out. Results. At both ±10 and ±25 µm displacement, a stick fretting regime was realised. Subsurface transformation in the Ti6Al4V alloy was characterised as strain-induced orientation. At ±50 µm, a mixed fretting regime was realised, TEM and SAED micrographs as well as EDX spectroscopy identified complex but distinctive structures at the surface and subsurface of the Ti6Al4V alloy. This included a CoCrMo-rich fine particulate, mechanically mixed structure, an amorphous-transformed Ti6Al4V structure and a highly refined nano-crystalline Ti6Al4V structure. At ±150 µm, a full gross slip regime was realised and Ti6Al4V alloy was characterised mainly by subsurface cracks, formation and refinement of nano-crystalline structures. Conclusion. The degree of subsurface recrystallization within Ti6Al4V alloy was observed to be energy dependent. However, the manifestation of the dissipated energy was dependent on the contact condition. The interwoven relationship between energy dissipation, contact condition and mechanisms of clinical failure in Ti6Al4V was consolidated into a map (Figure 1). The map is intended to provide users with an indication of the failure modes to expect for an implant material subjected to specific tribocorrosion conditions. For any figures or tables, please contact the authors directly

Surface replacement of the hip was established in the 1970's as a bone preserving alternative to total hip replacement. However, problems with femoral neck fracture, osteolysis, and component loosening led to early failures and an abandonment of the procedure. The modern generation of hip resurfacing, however, has improved upon past results with new implant designs and materials. Better surgical guides and a short femoral stem allow for more accurate placement of the implants. A metal-on-metal articulation creates a larger diameter bearing and avoids polyethylene wear debris. Also paramount in the recent successes of surface replacement are refinements in surgical techniques, leading to more accurate component positioning, avoidance of neck notching, and an appreciation of the femoral head blood supply. It has been well-established that surgeons with higher volumes of hip resurfacing operations have a lower complication rate. The mid-term results of these newer hip resurfacing devices, coupled with appropriate patient selection and good surgical technique, have been encouraging. Although, more recently, surface replacement has come under fire because of the metal-on-metal articulation, the Australian National Joint Registry finds that a certain group of patients has greater survivorship with resurfacing than with total hip replacement. Additionally, the benefits of surface replacement include the preservation of bone, a lower dislocation rate, and potentially a higher activity level. Therefore, the presenter feels that surface replacement arthroplasty is still a viable option, for the right patient and surgeon

Background. Recent advances in materials and manufacturing processes for arthroplasty have allowed fabrication of intricate implant surfaces to facilitate bony attachment. However, refinement and evaluation of these new design strategies is hindered by the cost and complications of animal studies, particularly during early iterations in development process. To address this problem, we have constructed and validated an ex-vivo bone bioreactor culture system to enable empirical testing of candidate structures and materials. In this study, we investigated mineralization of a titanium wire mesh scaffold under both static and dynamic culturing using our ex vivo bioreactor system. Methods. Cancellous cylindrical bone cores were harvested from bovine metatarsals and divided into five groups under different conditions. After incubation for 4 & 7 weeks, the viability of each bone sample was evaluated using Live-Dead assay and microscopic anatomy of cells were determined using histology stain H&E. Matrix deposits on the scaffolds were examined with scanning electron microscopy (SEM) while its chemical composition was measured using energy-dispersive x–ray spectroscopy (EDX). Results. The viability of bone cores was maintained after seven weeks using our protocol and ex vivo system. From SEM images, we found more organic matrix deposition along with crystallite like structures on the metal samples pulled from the bioreactor indicating the initial stages of mineralization. EDX results further confirmed the presence of carbon and calcium phosphates in the matrix. Conclusion. A bone bioreactor can be used a tool alternate to in-vivo for bone ingrowth studies on new implant surfaces or coatings

Refinement of surgical techniques, anesthesia protocols, and patient selection has facilitated this transformation to same day discharge for arthroplasty care, most notably Partial Knee Arthroplasty (PKA). The trend for early discharge has already happened for procedures formerly regarded as “inpatient” procedures such as upper extremity surgery, arthroscopy, ACL reconstruction, foot and ankle procedures, and rotator cuff repair. Our program began focused on PKA and has now expanded to primary TKA and THA, and select revision cases. Over the past few years we have performed 1,230 knee arthroplasty procedures with no readmissions for pain control. Average age and age range is identical to our inpatient cohort for our partial knee cases. Patient selection is based on medical screening criteria and insurance access. PKA is the ideal procedure to begin your transition to the outpatient space. We currently perform medial PKA, lateral PKA, and patellofemoral arthroplasty as an outpatient. The program centers on the patient, their family, home recovery, preoperative education, efficient surgery, and represents a shift in the paradigm of arthroplasty care. It can be highly beneficial to patients, surgeons, anesthesia, facility costs, and payors as arthroplasty procedures shift to the outpatient space. Perhaps the most significant developments in joint replacement surgery in the past decade have been in the area of multimodal pain management. This has reduced length of stay in the inpatient hospital environment opening the opportunity for cost savings and even outpatient joint replacement surgery for appropriately selected patients. The hallmark of this program is meticulous protocol execution. Preemptive pain control with oral anti-inflammatory agents, gabapentin, regional anesthetic blocks that preserve quad function for TKA (adductor canal block) and pericapsular long acting local anesthetics with the addition of injectable ketorolac and IV acetaminophen are key adjuncts. Over the past two years utilizing this type of program over 60% of our partial knee replacement patients are now returning home the day of surgery. Concerns over readmission are appropriate. The rates of complications and readmissions are less than our inpatient cohort in appropriately selected cases with a standardised care map. We believe this brings the best VALUE to the patients, surgeons, and the arthroplasty system

Refinement of surgical techniques, anaesthesia protocols, and patient selection have facilitated this transformation to same day discharge for arthroplasty care, most notably Partial Knee Arthroplasty (PKR). The trend for early discharge has already happened for procedures formerly regarded as “inpatient” procedures such as upper extremity surgery, arthroscopy, ACL reconstruction, foot and ankle procedures, and rotator cuff repair. Our program began focused on Partial Knee Arthroplasty (PKA) and has now expanded to primary TKA and THA, and select revision cases. Over the past few years we have performed 1,230 Knee Arthroplasty procedures with no readmissions for pain control. Average age and age range is identical to our inpatient cohort for our partial knee cases. Patient selection is based on medical screening criteria and insurance access. PKA is the ideal procedure to begin your transition to the outpatient space. We currently perform medial PKA, lateral PKA, and patellofemoral arthroplasty as outpatient cases. The program centers on the patient, their family, home recovery, pre-operative education, efficient surgery, and represents a shift in the paradigm of arthroplasty care. It can be highly beneficial to patients, surgeons, anaesthesia, facility costs, and payors as arthroplasty procedures shift to the outpatient space. Perhaps the most significant developments in joint replacement surgery in the past decade have been in the area of multimodal pain management. This has reduced length of stay in the inpatient hospital environment opening the opportunity for cost savings and even outpatient joint replacement surgery for appropriately selected patients. The hallmark of this program is meticulous protocol execution. Pre-emptive pain control with oral anti-inflammatory agents, gabapentin, regional anesthetic blocks that preserve quad function for TKA (adductor canal block) and pericapsular long acting local anesthetics with the addition of injectable ketorolac and IV acetaminophen are key adjuncts. Over the past two years utilizing this type of program over 60% of our partial knee replacement patients are now returning home the day of surgery. Concerns over readmission are appropriate. The rates of complications and readmissions are less than our inpatient cohort in appropriately selected cases with a standardised care map. We believe this brings the best VALUE to the patients, surgeons, and the arthroplasty system

Yes the paradigm is changing!!!. Refinement of surgical techniques, anesthesia protocols, and patient selection has facilitated this transformation to same day discharge for arthroplasty care. The trend for early discharge has already happened for procedures formerly regarded as “inpatient” procedures such as upper extremity surgery, arthroscopy, ACL reconstruction, foot and ankle procedures, and rotator cuff repair. Our program began focused on Partial Knee Arthroplasty (PKA) and has now expanded to primary TKA and THA, and select revision cases. Over the past few years we have performed: 138 TKA, 111 THA, 244 Partial KA, 6 RevTKA, and 6 RevTHA with no readmissions for pain control. With preoperative Hgb above 11 combined with Tranexamic Acid we have had no transfusions. Medical optimization is critical to the safety and success of patient selection for same day discharge. We utilise a standardised format for preadmission testing. The program centers on the patient, their family, home recovery, preoperative education, efficient surgery, and represents a shift in the paradigm of arthroplasty care. It can be highly beneficial to patients, surgeons, anesthesia, facility costs, and payors as arthroplasty procedures shift to the outpatient space

Introduction. Pedicle screw fixation commonly uses a manual probe technique for preparation and insertion of the screw. However, the accuracy of obtaining a centrally located path using the probe is often dependent on the experience of the surgeon and may lead to increased complications. Fluoroscopy and navigation assistance improves accuracy but may expose the patient and surgeon to excessive radiation. DSG measures electrical conductivity at the tip and provides the surgeon with real-time audio and visual feedback based on differences in tissue density between cortical and cancellous bone and soft tissue. The authors investigated the effectiveness of DSG for training residents on safe placement of pedicle screws. Methods. 15 male cadaveric thoracolumbar spine specimens were fresh-frozen at the time of expiration. Residents were assigned 3 specimens each and randomised by pedicle side and order of technique for pedicle screw placement (free-hand versus DSG). Fluoroscopy and other navigation assistance were not used for pedicle preparation. All specimens were imaged using CT following insertion of all pedicle screws. The accuracy was assessed by a senior radiologist and graded as within (≤ 2mm breach) or outside (> 2mm breach) the pedicle. Results. 15 specimens were dissected in standard fashion to expose the thoracolumbar spine (T7-L5). 5 residents were randomised and assigned 3 specimens each to prepare bilateral pedicles from T8 to L5 (60 pedicles per resident) using either PediGuard or free-hand technique. A total of 249 pedicle screws were placed. Post-procedure CT scans demonstrated 214 (85.9%) screws within the pedicle. Breach rate for the DSG group was 8.2% and 19.7% for the non-DSG group, with an overall reduction of 58% (p=0.025). Conclusion. The use of Dynamic Surgical Guidance decreased the pedicle screw placement learning curve in residents, while improving breach rate by 58%. This study demonstrates that DSG has the potential for resident education and refinement in operative technique

Surface replacement of the hip was established in the 1970's as a bone preserving alternative to total hip replacement. However, problems with femoral neck fracture, osteolysis, and component loosening led to early failures and an abandonment of the procedure. The modern generation of hip resurfacing, however, has improved upon past results with new implant designs and materials. Better surgical guides and a short femoral stem allows for more accurate placement of the implants. A metal-on-metal articulation creates a larger diameter bearing and avoids polyethylene wear debris. Also paramount in the recent successes of surface replacement are refinements in surgical techniques, leading to more accurate component positioning, avoidance of neck notching, and an appreciation of the femoral head blood supply. The mid-term results of these newer hip resurfacing devices, coupled with appropriate patient selection and good surgical technique, have been encouraging. Although more recently surface replacement has come under fire because of the metal-on-metal articulation, the Australian National Joint Registry finds that a certain group of patients has greater survivorship with resurfacing than with total hip replacement. Therefore, the presenter feels that surface replacement arthroplasty is still a viable option in this subgroup of patients. Additionally, the benefits of surface replacement include the preservation of bone, a lower dislocation rate, and potentially a higher activity level

Introduction. The reconstructive hip surgeon is commonly faced with complex cases where severe bone loss makes conventional revision techniques difficult or impossible. This problem is likely to increase in future, as there is a good correlation between the degree of bone loss seen and number of previous total hip operations. In such situations, one alternative is the use impaction allografting with cement. This has captured the attention of the orthopaedic community because of its potential for reconstituting femoral bone stock. History. The first clinical reports of impaction allografting on the femoral side were in relation to revision with cementless stems. The use of morselised bone with cement on the femoral side was first reported by the Exeter group. Biology. The great enthusiasm with which this technique has been received is related to its biological potential to increase bone stock. The rapid revascularization, incorporation and remodelling of morselised compacted cancellous allograft differs dramatically from structural allografting where bone ingrowth usually is limited to 2–3 mm. Histological evidence for bony reconstitution has been presented from postmortem retrievals, and from biopsies at the time of trochanteric wire removal. Impaction allografting, performed with great attention to detail using appropriate equipment, represents an exciting reconstructive solution for contained femoral defects. Its role in larger and combined defects remains open to scrutiny. A number of technical issues with regards to allograft preparation and prosthetic design have been resolved over the past decade. The necessary intra-operative precautions are now appreciated, and the high complication rates seen in some centers have been explained in simple terms. Careful observation and cautious optimism are necessary as further refinements may well improve the predictability of the clinical results and expand the indications for this important addition to the armamentarium of the revision surgeon. The technique of impaction allografting of the femur has great potential, and is here to stay as a reconstructive solution to the deficient proximal femur in revision hip arthroplasty. Although many questions remain unanswered, the capacity for impaction allografting to act as a truly biologic augmentation of the proximal femur makes this technique the modern bridge from revision arthroplasty to reconstructive hip surgery

INTRODUCTION. Clinical studies have shown that the knee tends to experience laterally higher AP motion (posterior directed) than medially (Asano at al., 2001; Dennis et al., 2005; Hill et al., 2000; Moro Oka et al., 2007). Traditional posterior stabilized (PS) total knee arthroplasty (TKA) designs allow deep flexion stability and femoral rollback once cam/spine engagement occurs, however mechanical stability provided by tibial bearing conformity during early to mid-flexion is highly variable. In this study a computer knee model is used to compare AP kinematics in PS TKA designs while evaluating multiple sagittal tibia bearing conformities. We hypothesized that highly conforming designs would be necessary to promote AP stability prior to cam/spine engagement. METHOD. A specimen specific computer model consisting of the femur, tibia and fibula, as well as the contribution of the ligaments and capsule was virtually implanted with TKA designs of the appropriate size at 5° tibia slope with the posterior cruciate ligament sacrificed. A single PS femoral component was evaluated with five PS tibia bearing designs with variable sagittal conformity ratios ranging from 1.05:1 to 2.2:1 (conformity ratio = tibia bearing sagittal radius / femur sagittal condylar radius). Designs were fully conforming frontally, with cam/spine engagement beyond 90° flexion. In all designs, lateral conformity ratios were increased relative to medial conformity ratios to facilitate lateral femoral rollback. Resultant AP kinematic predictions were obtained for femoral Low Points (LP) during 1) envelope of motion during internal external (IE) laxity evaluation and 2) knee bend functional activity. RESULTS. Designs with increased conformity resulted in improved AP stability in early to mid-flexion. In the envelope of laxity evaluations (Figure 1), the Medial LP laxity was similar for the 1.05:1 and 1.15:1 designs (approximately 2–3mm from extension to flexion), but then increased for the 1.35:1, 1.55:1, and 2.20:1 designs. Lateral LP laxity was more similar in all designs, however the designs with lower medial conformity ratio tended to have a greater Lateral LP laxity. During the Knee Bend activity (Figure 2), minimal (<1mm) Medial LP AP motion occurred from extension to cam/spine engagement in both the 1.05:1 and 1.15:1 designs, and greater AP motion occurred in the remaining designs. DISCUSSION. This study demonstrates that similar knee kinematics in PS TKA can be achieved over a small range of sagittal conformities, when designs approach 1:1 conformity. More conforming medial geometries can lead to greater lateral LP motion, suggesting greater medial conformity is necessary to replicate normal knee kinematics. Further work could evaluate impact of other factors such as tibia slope, further refinement in conformity, and additional specimen sizes. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Background. Data on varus-valgus and rotational profiles can be obtained during navigated total knee arthroplasty (TKA). Such intraoperative kinematic data might provide instructive clinical information for refinement of surgical techniques, as well as information on the anticipated postoperative clinical outcomes. However, few studies have compared intraoperative kinematics and pre- and postoperative clinical outcomes; therefore, the clinical implications of intraoperative kinematics remain unclear. In clinical practice, subjects with better femorotibial rotation in the flexed position often achieve favorable postoperative range of motion (ROM); however, no objective data have been reported to prove this clinical impression. Hence, the present study aimed to investigate the correlation between intraoperative rotation and pre- and postoperative flexion angles. Materials and Methods. Twenty-six patients with varus osteoarthritis undergoing navigated posterior-stabilized TKA (Triathlon, Stryker, Mahwah, NJ) were enrolled in this study. An image-free navigation system (Stryker 4.0 image-free computer navigation system; Stryker) was used for the operation. Registration was performed after minimum soft tissue release and osteophyte removal. Then, maximum internal and external rotational stress was manually applied on the knee with maximum extension and 90° flexion by the same surgeon, and the rotational angles were recorded using the navigation system. After knee implantation, the same rotational stress was applied and the rotational angles were recorded again. In addition, ROM was measured before surgery and at 1 month after surgery. The correlation between the amount of pre- and postoperative tibial rotation and ROM was statistically evaluated. Results. The amount of tibial rotation at registration was positively correlated with that after surgery (p < 0.05). Although the amount of tibial rotation at maximum extension was not correlated with ROM, the amount of rotation at 90° flexion at registration was positively correlated with pre- and postoperative ROM (p < 0.05). Moreover, the amount of tibial rotation at 90° flexion was positively correlated with postoperative ROM (p < 0.05). Conclusion. It is well known that preoperative ROM affects postoperative ROM. Our results showed that better tibial rotation at 90° flexion predicts favorable postoperative ROM, suggesting that flexibility of the surrounding soft tissues as well as the quadriceps muscles is an important factor for obtaining better ROM. Further evaluation of navigation-based kinematics during TKA surgery may provide useful information on ROM

Total knee replacement (TKA) surgery is an excellent and well-proven procedure for the treatment of end stage arthritis of the knee. Many refinements have taken place over time in an attempt to improve the components, wear qualities of the polyethylene, and the surgical technique to improve accuracy of component positioning, reduce patient pain, improve postoperative range of motion, ultimately improve results and to prolong the time until revision surgery may occur. This study examines the results of a gap balancing surgical technique in which components were implanted that had a posterior cruciate substituting design. This technique is performed with exacting alignment and balancing of the flexion and extension gaps prior to implantation of the knee components. The follow up is at a minimum of ten years. 515 consecutive knee replacements were followed prospectively for a minimum of ten years. The average age at surgery was 70 years, 73% of patients were female, with an average BMI of 31. All patients carried a diagnosis of osteoarthritis and a cemented, posterior stabilized design TKA (Balanced Knee System, Ortho Development) was implanted. All cases were performed by one of two experienced joint replacement surgeons. The surgical technique demanded flexion and extension gap balancing as well as soft tissue balancing prior to finishing cuts being performed on the femoral side (See figures 1 and 2). Polyethylene spacers come in 1 millimeter increments. 28% of patients died postoperatively at an average of 7.4 years. These patients were older on average at the time of index surgery (76.6 years). None had undergone revision surgery. Of the remaining patients Knee Society scores (39 preop to 91 post op at ten years), function scores and range of motion all improved significantly. What's more, these results were not diminished at ten years. There were no component failures and less than 1% radiographic progressive lucent lines. Eleven revision surgeries (2.1 %) were performed with 2 acute superficial wound revisions, 3 late infections, one patellar tendon disruption from a fall at 7 years (BMI 45.7), 2 complete revisions performed elsewhere for unsatisfactory results, and 3 spacer exchanges for perception of postoperative laxity. For the current study we also examined subgroups of the morbidly obese, octogenarians, and those with a preoperative valgus deformity of greater than 15%. At follow-up these subgroups fared very well with the exception of the heaviest BMI's being limited in range of motion because of soft tissue impingement. Results suggest that this balancing technique gives excellent results with few complications at ten year evaluation. We believe that careful attention to bony and soft tissue balancing and equalization of gaps in flexion and in extension will prove beneficial for TKA longevity in even longer-term evaluation. Figures 1 and 2 demonstrate gap balancing blocks and alignment rods in extension and in flexion

The initial success of modern total hip arthroplasty can in large part be attributed to the reliable fixation of the femoral component with the use of acrylic bone cement. Early success with cement led to a common pathway of development in North America and the European countries. Much of the early- to mid-term research concentrated on refinement of variables related to the methodology and technique of cement fixation. Scandinavian registries were subsequently able to report on improved survivorship with better cementing technique. The net effect has been standardisation towards a small number of cemented implants with good long-term outcomes representing the majority of stems implanted in Sweden, for example. In North America, during the mid-term development of THA in the late 1980's, the term “cement disease” was coined and the cemented THA saw a precipitous decline in use, now to the point where many American orthopaedic residents are completing training never having seen a cemented THA. Modern uncemented femoral components can now claim good long-term survivorship, perhaps now comparable to cemented fixation. However, this has come at a cost with respect to the premium expense applied to the implant itself as well as lineage of failed uncemented constructs. The last several years have seen a proliferation of uncemented implants, usually at a premium cost, with no demonstrated improvement in survivorship. Osteolysis has not been solved with uncemented implants and cement disease has largely been recognised as a misnomer. Long-term outcomes of cemented femoral fixation have consistently demonstrated excellent survivorship, even in the younger age group. Cemented stems allow for variable positioning of the stem to allow for better soft tissue balancing, without the need for proximal modularity. Cemented stems are more forgiving and fail less often secondary to a reduced incidence of intraoperative complications, such as periprosthetic fracture. Cemented stems tend to be less expensive and also have the advantage of adding antimicrobial agents into the cement. This is important in emerging markets. The next iteration of orthopaedic innovation driven by the emerging markets may indeed be back to the future