The use of virtual reality to assess the bony landmarks at the knee joint - The role of imaging modality and the assessor's experience.

BACKGROUND: At present, extended reality technologies such as virtual reality (VR) have gained popularity in orthopedic surgery. The first aim of this study was to assess the precision of VR and other imaging modalities - computed tomography (CT), magnetic resonance imaging (MRI) - to localize bony landmarks near the knee joint. Secondly, the impact of the educational level of the assessor - medical master students, orthopedic residents, and orthopedic surgeons - on the precision with which landmarks near the knee joint could be localized was analyzed. METHODS: We included a total of 77 participants: 62 medical master students, 10 orthopedic residents, and 5 orthopedic surgeons to analyze three cadaver legs. Every participant localized a series of sixteen bony landmarks on six different imaging modalities (CT, MRI, 3D-CT, 3D-MRI, VR-CT, VR-MRI). RESULTS: Concerning the imaging modality, the inter- and intra-observer variability were lowest for 3D and VR, higher for MRI (respectively 7.6 mm and 6.9 mm), and highest for CT (respectively 9 mm and 8.7 m).Concerning the educational level of the assessor, inter- and intra-observer variability in VR were lowest for surgeons, (respectively 3.2 mm and 3.6 mm), higher for residents (respectively 5.9 mm and 6.5 mm) and medical students (respectively 5.9 mm and 5.8 mm). CONCLUSIONS: VR can be considered a reliable imaging technique. Localization of landmarks tends to be more precise in VR and on 3D than on conventional CT and MRI images. Furthermore, orthopedic surgeons localize landmarks more precisely than orthopedic residents and medical students in VR.

A robotic-assisted simulation of kinematic alignment in TKA leads to excessive valgus and internal rotation in valgus knees.

PURPOSE: Strategies to further improve patient satisfaction after total knee arthroplasty include the introduction of new alignment philosophies and more precise instruments such as navigation and robotics. The aim of this study was to investigate the effect of a combination of image-based robotic assistance and the use of modern alignment strategies on the resulting joint line obliquity as well as femoral component rotation and to compare this between varus, neutral and valgus knees. METHODS: This retrospective study included 200 patients who received a robotic-assisted total knee arthroplasty (MAKO®, Stryker) using functional alignment between 2018 and 2020. The patients were divided into a varus (103 patients), neutral (57 patients) and valgus (40 patients) group. The intraoperatively recorded bone cuts and resulting joint line obliquity were identified and compared to values obtained with a robotic computer simulation of kinematic alignment. RESULTS: The mean femoral coronal alignment of the varus, neutral and valgus group, respectively, equalled 0.5° (± 1.1°), 1.1° (± 0.8°) and 1.6° (± 0.7°) of valgus with functional alignment and 2.1° (± 2.1°), 4.1° (± 1.7°) and 6.2° (± 1.7°) of valgus with kinematic alignment. The mean femoral axial alignment of the valgus group resulted in 0.8° (± 2.0°) of internal rotation with functional alignment and 3.9° (± 2.8°) of internal rotation with kinematic alignment. Overall, 186 knees (93%) could be balanced while respecting certain safe zones by using functional alignment as opposed to 54 knees (27% and none in the valgus group) when applying kinematic alignment. Kinematic alignment led to a combination of femoral component valgus and internal rotation of more than 3° in 22 valgus knees (55%), 10 neutral knees (18%) and 3 varus knees (3%) compared to none in each group when applying functional alignment with safe zones. CONCLUSIONS: Robotic-assisted kinematic alignment leads to a combination of excessive valgus and internal rotation of the femoral component in valgus and to a lesser extent also in neutral knees when compared with functional alignment. LEVEL OF EVIDENCE: IV.

Knee kinematics during staircase descent.

The goal was to evaluate tibiofemoral knee joint kinematics during stair descent, by simulating the full stair descent motion in vitro. The knee joint kinematics were evaluated for two types of knee implants: bi-cruciate retaining and bi-cruciate stabilized. It was hypothesized that the bi-cruciate retaining implant better approximates native kinematics. The in vitro study included 20 specimens which were tested during a full stair descent with physiological muscle forces in a dynamic knee rig. Laxity envelopes were measured by applying external loading conditions in varus/valgus and internal/external direction. The laxity results show that both implants are capable of mimicking the native internal/external-laxity during the controlled lowering phase. The kinematic results show that the bi-cruciate retaining implant tends to approximate the native condition better compared to bi-cruciate stabilized implant. This is valid for the internal/external rotation and the anteroposterior translation during all phases of the stair descent, and for the compression-distraction of the knee joint during swing and controlled lowering phase. The results show a better approximation of the native kinematics by the bi-cruciate retaining knee implant compared to the bi-cruciate stabilized knee implant for internal/external rotation and anteroposterior translation. Whether this will result in better patient outcomes remains to be investigated.

The Definition of the Tibial Sagittal Plane and the Paradox of Imageless Navigation and Robotics: A Cadaveric Study.

BACKGROUND: The accuracy, precision, and repeatability by which the tibial sagittal plane can be found with imageless technology is currently unknown. The purpose of this study was to identify any differences between imageless and image-based technology to define the sagittal plane of the tibia. METHODS: A computed tomography (CT) was obtained of 18 cadavers with the knee fully extended. The surgical trans-epicondylar axis and several tibial rotation references were acquired on the CT scan. After a medial parapatellar approach, the same anatomical landmarks were acquired in vivo. In the horizontal plane, the angle between the surgical trans-epicondylar axis and the tibial rotational axes was assessed. RESULTS: Highest accuracy was found for posterior cruciate ligament (PCL)-anterior cruciate ligament (ACL, -1.48°, standard deviation [SD] 13.64; imageless), tibial medial condyle (TMC)-tibial lateral condyle (TLC, 1.72°, SD 4.24; image-based), the ACL-medial border of tibial tuberosity (MTT, -2.89°, SD 18.86; image-based). Highest precision was acquired with image-based technology: TMC-TLC (SD 4.24), PCL-ACL (SD 5.86), and PCL-medial third of tibial tuberosity (M3TT, SD 7.10). Excellent intraobserver and interobserver correlation coefficients were observed with image-based technology: PCL-MTT, anterior medial condyle (AMC)-anterior lateral condyle (ALC), and TMC-TLC (Intraobserver and interobserver correlation coefficients 0.90-0.98). CONCLUSION: The tibial sagittal plane could be defined with highest accuracy, precision, and repeatability on a preoperative CT. Imageless methodology lacked the precision and repeatability of image-based technology. With the current pursuit of high accuracy and precision in total knee arthroplasty, the reference frame used to quantify implant position should be highly accurate and precise as well. LEVEL OF EVIDENCE: IV, Case Series.

Intratendinous pressure changes in the Achilles tendon during stretching and eccentric loading: Implications for Achilles tendinopathy.

Mechanical overload is considered the main cause of Achilles tendinopathy. In addition to tensile loads, it is believed that the Achilles tendon may also be exposed to compressive loads. However, data on intratendinous pressures are lacking, and consequently, their role in the pathophysiology of tendinopathy is still under debate. Therefore, we aimed to evaluate the intratendinous pressure changes in the Achilles tendon during stretching and eccentric loading. Twelve pairs of human cadaveric legs were mounted in a testing rig, and a miniature pressure catheter was placed through ultrasound-guided insertion in four different regions of the Achilles tendon: the insertion (superficial and deep layers), mid-portion, and proximal portion. Intratendinous pressure was measured during three simulated loading conditions: a bent-knee calf stretch, a straight-knee calf stretch, and an eccentric heel-drop. It was found that the intratendinous pressure increased exponentially in both the insertion and mid-portion regions of the Achilles tendon during each loading condition (p < 0.001). The highest pressures were consistently found in the deep insertion region (p < 0.001) and during the eccentric heel-drop (p < 0.001). Pressures in the mid-portion were also significantly higher than in the proximal portion (p < 0.001). These observations offer novel insights and support a role for compression in the pathophysiology of Achilles tendinopathy by demonstrating high intratendinous pressures at regions where Achilles tendinopathy typically occurs. To what extent managing intratendinous pressure might be successful in patients with Achilles tendinopathy by, for example, avoiding excessive stretching, modifying exercise therapy, and offering heel lifts requires further investigation.

Effect of iliotibial band and gastrocnemius activation on knee kinematics.

BACKGROUND: This paper aimed to evaluate the effects of iliotibial band (ITB) activation and gastrocnemius activation on knee kinematics and stability. A quantitative analysis needs to determine the effect of ITB and gastrocnemius activation in each of the six degrees of freedom of the knee joint. METHODS: Four cadaveric knee specimens were tested during squat motions with physiological loads. The quadriceps and hamstring muscles were activated in each situation. The ITB was intermittently activated using an actuator and a cable pulley system. The gastrocnemius was activated anatomically as part of the triceps surae complex together with the soleus and the plantaris muscle. During the squat motion, the Achilles tendon has increased tension which induced muscle activation in the calf muscles thus creating the activated situation. RESULTS: Introduction of the ITB resulted in a reduced laxity width during extension and an external tibial rotation (2.4°). The femur shifted less posterior in the lateral compartment when the ITB was activated. Activation of gastrocnemius as part of the calf muscles led to an increased laxity width. CONCLUSIONS: Knee stability and knee joint kinematics are affected significantly by the activation of the ITB and the gastrocnemius as part of the triceps surae complex. This points to the importance of muscles and stabilizing tissue structures such as the ITB in the evaluation of knee joint kinematics both in vitro and in vivo.

The learning curve of imageless robot-assisted total knee arthroplasty with standardised laxity testing requires the completion of nine cases, but does not reach time neutrality compared to conventional surgery.

PURPOSE: The assistance of robot technology is introduced into the operating theatre to improve the precision of a total knee arthroplasty. However, as with all new technology, new technology requires a learning curve to reach adequate proficiency. The primary aim of this study was to identify the learning curve of an imageless robotic system with standardised laxity testing. The secondary aim of this study was to evaluate the accuracy of the intra-operative coronal alignment during the learning curve. METHODS: A prospective study was performed on 30 patients undergoing robot-assisted total knee arthroplasty with an imageless robotic system (Corin, Massachusetts, USA) associated with a dedicated standardised laxity testing device. The learning curve of all surgical steps was assessed with intra-operative video monitoring. As comparison, the total surgical time of the last 30 patients receiving conventional total knee arthroplasty by the same surgeon and with the same implant was retrospectively assessed. Coronal lower limb alignment was evaluated pre- and post-operatively on standing full-leg radiographs. RESULTS: CUSUM (cumulative summation) analysis has shown inflexion points in multiple steps associated with robot-assisted surgery between one and 16 cases, which indicates the progression from the learning phase to the proficiency phase. The inflexion point for total operative time occurred after nine cases. Robot-assisted total knee surgery required significantly longer operative times than the conventional counterpart, with an average increase of 22 min. Post-operative limb and implant alignment was not influenced by a learning curve. CONCLUSION: The introduction of an imageless robotic system with standardised laxity assessment for total knee arthroplasty results in a learning curve of nine cases based on operative time. Compared to conventional surgery, the surgeon is not able to reach time neutrality with the robotic platform. There is no learning curve associated with coronal limb or implant alignment. This study enables orthopaedic surgeons to understand the implementation of this surgical system and its specific workflow into clinical practice.

Accuracy of intraoperative bone registration and stereotactic boundary reconstruction during total knee arthroplasty surgery.

BACKGROUND: The intraoperative registration of the bones play a crucial role in image-based computer-assisted knee arthroplasty to achieve accurate implant placement and to create reliable stereotactic bone boundaries for robot-assisted surgical systems. METHOD: This study assessed the intraoperative registration accuracy on six intact fresh frozen cadavers. RESULTS: Rotational errors around the mechanical axis were the largest, with a standard deviation of 1.2° and outliers up to 3.7°. The mean translational errors were lower than 1 mm, with outliers up to 1.5 mm. These errors were amplified to 2 mm for the registration-based reconstruction of the posterior bone surface at the resection levels. CONCLUSION: Given the cumulative behaviour of surgical errors, registration errors can affect the final implant positioning. Furthermore, inaccuracies in the reconstructed bone boundary directly affect the virtual stereotactic boundaries used in robotic-assisted surgery and can result in an incomplete resection or inadvertent soft tissue damage.

The evolution of robotic systems for total knee arthroplasty, each system must be assessed for its own value: a systematic review of clinical evidence and meta-analysis.

INTRODUCTION: Robotic systems have been introduced to improve the precision of total knee arthroplasty. However, different robotic systems are available, each with unique features used to plan and execute the surgery. As such, due to this diversity, the clinical evaluation of each robotic platform should be separated. METHODS: An extensive literature search of PubMed, Medline, Embase and Web of Science was conducted with subsequent meta-analysis. Randomised controlled trials, comparative studies, and cohort studies were included regarding robot-assisted total knee arthroplasty. Evaluated outcomes included clinical results, surgical precision, ligament balance, surgical time, learning curve, complications and revision rates. These were split up based on the robot-specific brand: ROBODOC (T-SOLUTION ONE), OMNIBOT, MAKO, NAVIO (CORI) and ROSA. RESULTS: With a follow-up of more than 10 years, no improved clinical outcomes have been noted with the ROBODOC system compared to the conventional technique. If available, other platforms only present short-term clinical outcomes. Radiological outcomes are published for most robotic setups, demonstrating improved surgical precision compared to the conventional technique. Gap balance assessment is performed differently between all systems, leading to heterogeneous outcomes regarding its relationship on clinical outcomes. There is a similar learning curve based on operative time for all robotic platforms. In most studies, robot assistance requires longer operative time compared to the conventional technique. Complications and revision rates are published for ROBODOC and MAKO, without clear differences to conventional total knee arthroplasty. CONCLUSION: The main finding of this systematic review is that the current evidence regarding each robotic system is diverse in quantity and quality. Each system has its own specificities and must be assessed for its own value. Regarding scientific literature, the generic term of robotic should be banned from the general conclusion. LEVEL OF EVIDENCE: Systematic review level IV.

Robot-assisted total knee arthroplasty is associated with a learning curve for surgical time but not for component alignment, limb alignment and gap balancing.

PURPOSE: The application of robotics in the operating theatre for total knee arthroplasty (TKA) remains controversial. As with all new technology, the introduction of new systems is associated with a learning curve and potentially associated with extra complications. Therefore, the aim of this study is to identify and predict the learning curve of robot-assisted (RA) TKA. METHODS: A RA TKA system (MAKO) was introduced in April 2018 in our service. A retrospective analysis was performed of all patients receiving a TKA with this system by six surgeons. Operative times, implant and limb alignment, intraoperative joint balance and robot-related complications were evaluated. Cumulative summation (CUSUM) analyses were used to assess learning curves for operative time, implant alignment and joint balance in RA TKA. Linear regression was performed to predict the learning curve of each surgeon. RESULTS: RA TKA was associated with a learning curve of 11-43 cases for operative time (p < 0.001). This learning curve was significantly affected by the surgical profile (high vs. medium vs. low volume). A complete normalisation of operative times was seen in four out of five surgeons. The precision of implant positioning and gap balancing showed no learning curve. An average deviation of 0.2° (SD 1.4), 0.7° (SD 1.1), 1.2 (SD 2.1), 0.2° (SD 2.9) and 0.3 (SD 2.4) for the mLDFA, MPTA, HKA, PDFA and PPTA from the preoperative plan was observed. Limb alignment showed a mean deviation of 1.2° (SD 2.1) towards valgus postoperatively compared to the intraoperative plan. One tibial stress fracture was seen as a complication due to suboptimal positioning of the registration pins. CONCLUSION: RA TKA is associated with a learning curve for surgical time, which might be longer than reported in current literature and dependent on the profile of the surgeon. There is no learning curve for component alignment, limb alignment and gap balancing. LEVEL OF EVIDENCE: IV.

Equal bony resection of distal and posterior femur will lead to flexion/extension gap inequality in robot-assisted cruciate-retaining TKA.

PURPOSE: Joint imbalance has become one of the main reasons for early revision after total knee arthroplasty (TKA) and it is directly related to the surgical technique. Therefore, a better understanding of how much bone has to be removed to obtain a balanced flexion/extension gap could improve current practice. The primary objective of this study was to analyse the amount of bone that needed to be removed from the distal and posterior femoral joint surfaces to obtain an equal flexion/extension gap in robot-assisted TKA. The second objective of this study was to evaluate whether the size of the knee joint influenced the amount of bony resection needed to achieve an equal flexion/extension gap in robot-assisted TKA. METHODS: A retrospective analysis was performed on all patients receiving a robot-assisted TKA (Cruciate Retaining (n = 268)) by six surgeons from April 2018 to September 2019. The robot was used consecutively when available in all patients receiving Cruciate Retaining TKA. Gap assessment, bony resections, femoral implant size and hip-knee-ankle angle were evaluated with the robot. Femoral implant size was categorized into small (size 1-2), medium (size 3-5) and large (size 6-8). RESULTS: The difference between the posterior and distal resection needed to obtain equal flexion and extension gap was on average 2.0 mm (SD 1.6) and 1.5 mm (SD 2.2) for the medial and lateral compartment, respectively. The discrepancy was smaller in the large implant group compared to the small implant group (p < .05 medial and lateral) and medium implant group (p < .05 medial). Varus knees required a larger differential resection compared to neutral and valgus knees (only laterally) (medial compartment: p < .05 (varus-neutral), p = .051 (varus-valgus); lateral compartment: p < .05 (varus-neutral and varus-valgus). CONCLUSION: Removing an equal amount of bone from the distal and posterior femur will lead to flexion/extension gap imbalance in TKA. It was required to remove 1.5-2 mm more bone from the posterior femur compared to the distal femur to equalize flexion and extension gap. This effect was size dependent: in larger knees, the discrepancy between the distal and posterior resections was smaller. LEVEL OF EVIDENCE: IV.

Which Fracture Types Are Associated with Widening of the Scapholunate Distance? A CT-Scan Study of Acute Intraarticular Distal Radius Fractures.

Background: Scapholunate injuries in distal radius fractures may frequently be overlooked. The aims of this study were to measure the scapholunate distance in intraarticular distal radius fractures and to find out which fracture types were associated with an increased scapholunate width. Methods: Measurements of the scapholunate distance were performed on computed tomography scans of 143 intraarticular distal radius fractures in 140 patients. The fractures were classified according to the AO classification. The morphology of AO type B fractures was further analysed according to the Bain classification. Results: In 43 AO type B fractures mean scapholunate distance measured 2.1 mm and in 100 type C fractures 1.6 mm. The difference between partial and complete intraarticular fractures was significant. A trend towards a greater scapholunate distance was found in AO type B1 and radial styloid oblique fractures. Conclusions: In this study, partial intraarticular distal radius fractures, especially with a sagittal split, had a greater scapholunate distance and may be at risk for ligamentous injury.

Custom TKA: what to expect and where do we stand today?

INTRODUCTION: The concept of custom total knee arthroplasty (TKA) is explored with specific attention to current limitations. Arguments in favor of custom TKA are the anatomic and functional variability we encounter in our patients. The biggest conceptual challenge is to marry the need for correction of deformity with the ambition to stay as close as possible to original anatomy. MATERIALS AND METHODS: A Pubmed search was performed on the following terms: 'patient specific implant', 'custom made implant', 'custom implant', 'total knee arthroplasty' and 'total knee replacement'. These studies were evaluated for the following intra- and post-operative variables: blood loss, hospital stay, range of motion, patient-reported outcome measures, limb and implant alignment, implant fit, tibiofemoral kinematics, complications and revision rates. RESULTS: Out of 1117 studies found with the initial search, a total of 17 articles were included in the final analysis. In eight out of the 17 (47%) studies, either the research was commercially funded or one of the authors had a conflict of interest related to the work. 11 out of 17 studies included a control group in their study setup. Of those studies that included a control group, both superior and inferior results compared to off-the-shelf implants have been reported. CONCLUSION: Custom knee implants are the next step in matching the geometric features of the prosthesis to the anatomy of the individual patient, after several iterations that added asymmetry and sizes in the existing implants. Several companies have proven that it is feasible to produce these implants in a safe way. An overview of current literature reveals the lack of strong methodological studies that prove the value of this new technology. Custom knee implants face conceptual and practical difficulties, some of which might be overcome with technological advances, such as robotics and artificial intelligence.

Biceps Femoris Compensates for Semitendinosus After Anterior Cruciate Ligament Reconstruction With a Hamstring Autograft: A Muscle Functional Magnetic Resonance Imaging Study in Male Soccer Players.

BACKGROUND: Rates of reinjury, return to play (RTP) at the preinjury level, and hamstring strain injuries in male soccer players after anterior cruciate ligament reconstruction (ACLR) remain unsatisfactory, due to multifactorial causes. Recent insights on intramuscular hamstring coordination revealed the semitendinosus (ST) to be of crucial importance for hamstring functioning, especially during heavy eccentric hamstring loading. Scientific evidence on the consequences of ST tendon harvest for ACLR is scarce and inconsistent. This study intended to investigate the repercussions of ST harvest for ACLR on hamstring muscle function. HYPOTHESIS: Harvest of the ST tendon for ACLR was expected to have a significant influence on hamstring muscle activation patterns during eccentric exercises, evaluated at RTP in a population of male soccer athletes. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 30 male soccer players with a history of ACLR who were cleared for RTP and 30 healthy controls were allocated to this study during the 2018-2019 soccer season. The influence of ACLR on hamstring muscle activation patterns was assessed by comparing the change in T2 relaxation times [ΔT2 (%) = post-exercise-T2pre-exerciseT2pre-exercise] of the hamstring muscle tissue before and after an eccentric hamstring loading task between athletes with and without a recent history of ACLR through use of muscle functional magnetic resonance imaging, induced by an eccentric hamstring loading task between scans. RESULTS: Significantly higher exercise-related activity was observed in the biceps femoris (BF) of athletes after ACLR compared with uninjured control athletes (13.92% vs 8.48%; P = .003), whereas the ST had significantly lower activity (19.97% vs 25.32%; P = .049). Significant differences were also established in a within-group comparison of the operated versus the contralateral leg in the ACLR group (operated vs nonoperated leg: 14.54% vs 11.63% for BF [P = .000], 17.31% vs 22.37% for ST [P = .000], and 15.64% vs 13.54% for semimembranosus [SM] [P = .014]). Neither the muscle activity of SM and gracilis muscles nor total posterior thigh muscle activity (sum of exercise-related ΔT2 of the BF, ST, and SM muscles) presented any differences in individuals who had undergone ACLR with an ST tendon autograft compared with healthy controls. CONCLUSION: These findings indicate that ACLR with a ST tendon autograft might notably influence the function of the hamstring muscles and, in particular, their hierarchic dimensions under fatiguing loading circumstances, with increases in relative BF activity contribution and decreases in relative ST activity after ACLR. This between-group difference in hamstring muscle activation pattern suggests that the BF partly compensates for deficient ST function in eccentric loading. These alterations might have implications for athletic performance and injury risk and should probably be considered in rehabilitation and hamstring injury prevention after ACLR with a ST tendon autograft.

Positioning of longest axis of the radial head in neutral forearm rotation.

INTRODUCTION: The radial head has an ellipsoid shape so that a longest and a shortest axis can be defined. The aim of this study is to evaluate the position of the longest axis of the radial head (LARH) in relation to proximal radioulnar joint (PRUJ) and to the forearm in neutral position using 3D computed tomography (CT). MATERIALS AND METHODS: 3D CT reconstructions of the distal humerus, the radius and the ulna of 27 healthy volunteers (average age 27.65 ± 9.25; 24 males, 3 females) were created. First an evaluation of the elliptic form of the radial head and the location of its longest axis was performed. Next, three planes were defined: the PRUJ plane, the forearm plane and a neutral plane. Based on the angle between the forearm plane and the neutral plane, the rotation of the scanned forearm was measured. Taking this rotation into account, the position of the LARH compared to PRUJ plane and forearm plane in neutral position is recalculated. RESULTS: The shape of the radial head is determined to be non-circular based on this study population (p < .001). In neutral position, the angle between the LARH and the forearm plane is 5.28° (SD: 15.09) and between the LARH and the PRUJ is 33.46° (SD: 13.91). CONCLUSIONS: The position of the LARH is found to be approximately perpendicular to the forearm plane when the forearm is in neutral position and perpendicular to the PRUJ plane when the forearm is on average in 30° of pronation.

Soft-tissue penetration of the oscillating saw during tibial resection in total knee arthroplasty.

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 75th 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.

How should we evaluate robotics in the operating theatre?

The application of robotics in the operating theatre for knee arthroplasty remains controversial. As with all new technology, the introduction of new systems might be associated with a learning curve. However, guidelines on how to assess the introduction of robotics in the operating theatre are lacking. This systematic review aims to evaluate the current evidence on the learning curve of robot-assisted knee arthroplasty. An extensive literature search of PubMed, Medline, Embase, Web of Science, and Cochrane Library was conducted. Randomized controlled trials, comparative studies, and cohort studies were included. Outcomes assessed included: time required for surgery, stress levels of the surgical team, complications in regard to surgical experience level or time needed for surgery, size prediction of preoperative templating, and alignment according to the number of knee arthroplasties performed. A total of 11 studies met the inclusion criteria. Most were of medium to low quality. The operating time of robot-assisted total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) is associated with a learning curve of between six to 20 cases and six to 36 cases respectively. Surgical team stress levels show a learning curve of seven cases in TKA and six cases for UKA. Experience with the robotic systems did not influence implant positioning, preoperative planning, and postoperative complications. Robot-assisted TKA and UKA is associated with a learning curve regarding operating time and surgical team stress levels. Future evaluation of robotics in the operating theatre should include detailed measurement of the various aspects of the total operating time, including total robotic time and time needed for preoperative planning. The prior experience of the surgical team should also be evaluated and reported. Cite this article: Bone Joint J 2020;102-B(4):407-413.

Three-dimensional correction of fibular hemimelia using a computer-assisted planning : technical report and literature review.

The purpose of this survey in Belgium and the Netherlands was to assess treatment variation in glenohumeral osteoarthritis between experienced and less experienced orthopedic surgeons, and to investigate perioperative treatment after shoulder arthroplasty in a large group of orthopedic surgeons. Orthopedic surgeons specialized in shoulder surgery were invited to complete a survey between November 2013 and February 2015. Seventy-one percent of the approached surgeons com-pleted the survey. Less experienced surgeons (< 6 years) and surgeons from the Netherlands find patient characteristics (e.g. smoking p=0.01) more relevant than more experienced surgeons (≥ 6 years) and surgeons from Belgium. Less experienced surgeons will less likely (p=0.001) perform resurfacing arthroplasty compare to experienced surgeons. The less and the experienced surgeons use similar indications for a reverse shoulder arthroplasty regarding age limit and cuff arthropathy without osteoarthritis. Less experienced surgeon will more likely (p=0.003) prescribe a low molecular weight heparin during the hospital stay after a shoulder arthroplasty. In this survey, we found a decrease in the use of resurfacing arthroplasty and a strong increase in the use of reverse shoulder arthroplasty. Besides, there is little consensus concerning pre-operative planning, patient characteristics, surgical technique, and patient reported outcome measures. Level of evidence: IV.

Templating of Syndesmotic Ankle Lesions by Use of 3D Analysis in Weightbearing and Nonweightbearing CT.

BACKGROUND:: Diagnosis and operative treatment of syndesmotic ankle injuries remain challenging due to the limitations of 2-dimensional imaging. The aim of this study was therefore to develop a reproducible method to quantify the displacement of a syndesmotic lesion based on 3-dimensional computed imaging techniques. METHODS:: Eighteen patients with a unilateral syndesmotic lesion were included. Bilateral imaging was performed with weightbearing cone-beam computed tomography (CT) in case of a high ankle sprain (n = 12) and by nonweightbearing CT in case of a fracture-associated syndesmotic lesion (n = 6). The healthy ankle was used as a template after being mirrored and superimposed on the contralateral ankle. The following anatomical landmarks of the distal fibula were computed: the most lateral aspect of the lateral malleolus and the anterior and posterior tubercle. The change in position of these landmarks relative to the stationary, healthy fibula was used to quantify the syndesmotic lesion. A control group of 7 studies was used. RESULTS:: The main clinical relevant findings demonstrated a statistically significant difference between the mean mediolateral diastasis of both the sprained (mean [SD], 1.6 [1.0] mm) and the fracture group (mean [SD], 1.7 [0.6] mm) compared to the control group ( P < .001). The mean external rotation was statistically different when comparing the sprained (mean [SD], 4.7 [2.7] degrees) and the fracture group (mean [SD], 7.0 [7.1] degrees) to the control group ( P < .05). CONCLUSION:: This study evaluated an effective method for quantifying a unilateral syndesmotic lesion of the ankle. Applications in clinical practice could improve diagnostic accuracy and potentially aid in preoperative planning by determining which correction needs to be achieved to have the fibula correctly reduced in the syndesmosis. LEVEL OF EVIDENCE:: Level III, retrospective comparative study.