Aims. The management of fractures of the medial epicondyle is one of the greatest controversies in paediatric fracture care, with uncertainty concerning the need for surgery. The British Society of Children’s Orthopaedic Surgery prioritized this as their most important research question in paediatric trauma. This is the protocol for a randomized controlled, multicentre, prospective superiority trial of operative fixation versus nonoperative treatment for displaced medial epicondyle fractures: the Surgery or Cast of the EpicoNdyle in Children’s Elbows (SCIENCE) trial. Methods. Children aged seven to 15 years old inclusive, who have sustained a displaced fracture of the medial epicondyle, are eligible to take part. Baseline function using the Patient-Reported Outcomes Measurement Information System (PROMIS) upper limb score, pain measured using the Wong Baker FACES pain scale, and quality of life (QoL) assessed with the EuroQol five-dimension questionnaire for younger patients (EQ-5D-Y) will be collected. Each patient will be randomly allocated (1:1, stratified using a minimization algorithm by centre and initial elbow dislocation status (i.e. dislocated or not-dislocated at presentation to the emergency department)) to either a regimen of the operative fixation or non-surgical treatment. Outcomes. At six weeks, and three, six, and 12 months, data on function, pain, sports/music participation, QoL, immobilization, and analgesia will be collected. These will also be repeated annually until the child reaches the age of 16 years. Four weeks after injury, the main outcomes plus data on complications, resource use, and school absence will be collected. The primary outcome is the PROMIS upper limb score at 12 months post-randomization. All data will be obtained through electronic questionnaires completed by the participants and/or parents/guardians. The NHS number of participants will be stored to enable future data linkage to sources of routinely collected data (i.e. Hospital Episode Statistics). Cite this article: Bone Jt Open 2024;5(1):69–77

Objectives. The purpose of this study was to develop an accurate, reliable and easily applicable method for determining the anatomical location of the joint line during revision knee arthroplasty. Methods. The transepicondylar width (TEW), the perpendicular distance between the medial and lateral epicondyles and the distal articular surfaces (DMAD, DLAD) and the distance between the medial and lateral epicondyles and the posterior articular surfaces (PMAD, DLAD) were measured in 40 knees from 20 formalin-fixed adult cadavers (11 male and nine female; mean age at death 56.9 years, . sd. 9.4; 34 to 69). The ratios of the DMAD, PMAD, DLAD and PLAD to TEW were calculated. Results. The mean TEW, DMAD, PMAD, DLAD and PLAD were 82.76 mm (standard deviation (. sd. ) 7.74), 28.95 mm (. sd. 3.3), 28.57 mm (. sd. 3), 23.97 mm (. sd. 3.27) and 24.42 mm (. sd. 3.14), respectively. The ratios between the TEW and the articular distances (DMAD/TEW, DLAD/TEW, PMAD/TEW and PLAD/TEW) were calculated and their means were 0.35 (. sd. 0.02), 0.34 (. sd. 0.02), 0.28 (. sd. 0.03) and 0.29 (. sd. 0.03), respectively. Conclusion. This method provides a simple, reproducible and reliable technique enabling accurate anatomical joint line restoration during revision total knee arthroplasty. Cite this article: B. Ozkurt, T. Sen, D. Cankaya, S. Kendir, K. Basarır, Y. Tabak. The medial and lateral epicondyle as a reliable landmark for intra-operative joint line determination in revision knee arthroplasty. Bone Joint Res 2016;5:280–286. DOI: 10.1302/2046-3758.57.BJR-2016-0002.R1

Restoration of joint line in total knee arthroplasty (TKA) is important for kinematics of knee and ligamentous balance. Especially in revision TKA, it may be difficult to identify the joint line. The aim of this study is to define the relationship between epicondyles and articular surface using CT based three-dimensional digital templating sofware $“Athena” (Soft Cube, Osaka, Japan). 137 knees with osteoarthritis, all caces were grade 2 or lower in Kellgren-Lawrence index, were investigated. Perpendicular lines were dropped from the prominences of the medial and lateral femoral epicondyles to the most distal points of articular surfaces and distances of the lines were measured on the axial and coronal planes. The femoral width was measured as the distance between medial and lateral epicondyles. Each of the distance described above was converted to a ratio by dividing by the femoral width. On the axial plane, the average distance from epicondyles to the posterior articular surfaces were 29.4±2.2mm on the medial side and 21.2±2.3mm on the lateral side. The average of the femoral width was 75.2±4.1mm. On coronal plane, the average distance from epicondyles to the distal articular surfaces were 25.2±2.8mm on the medial side and 21.4±2.5mm on the lateral side. The ratio for the distance from epicondyles to the distal and posterior joint line compared to femoral width was 0.39±0.02, 0.28±0.03, 0.33±0.03 and 0.28±0.03. The distance from epicondyles to the distal and posterior joint line correlates with the femoral width of the distal femur. This information can be useful in determining appropriate joint line

Abstract. The radiographic or bony landmark techniques are the two most common methods to determine Medial patellofemoral ligament (MPFL) femoral tunnel placement. Their intra/inter-observer reliability is widely debated. The palpation technique relies on identifying the medial epicondyle (ME) and adductor Tubercle (AT). The central longitudinal artery and associated vessels (CLV) are consistently seen in the surgical dissection during MPFL reconstruction. The aim of this study was to investigate the anatomic relationship of CLV to ME-AT and thereby use CLV as an important vascular landmark during MPFL reconstruction. A retrospective review of MRI scans in skeletally mature patients presenting to a tertiary referral knee clinic was undertaken. Group-N consisted of any presentation without patellofemoral instability or malalignment (PFI). Group-P with PFI. MRI's were reviewed and measured by two Consultant Radiologists for the CLV-ME-AT anatomy and relationship. Following exclusions 50 patients were identified in each group. The CLV passed anterior to the AT and ME in all patients. ME morphology did not differ greatly between the groups except in the tubercle height, where there was a statically but not clinically significant difference (larger in the non-PFI group, 2.95mm vs 2.52mm, p=0.002). The CLV to ME Tip distance was consistent between the groups (Group PFI group 3.8mm & ‘normal’ non-PFI Group 3.9mm). The CLV-ME-AT relationship remained consistent despite patients presenting pathology. The CLV consistently courses anterior to ME and AT. The CLV could be used as a vascular landmark assisting femoral tunnel placement during MPFL reconstruction

We performed a new operation for ulnar neuropathy caused by recurrent dislocation at the medial epicondyle. There were eleven patients, eight men and three women, with an average age of 52 years (24–74 years) at the time of surgery. The mean duration of symptoms was 23 months. The severity of the symptoms was McGowan grade 1 in five patients, grade 2 in five patients, and grade 3 in one patient. The operation consisted of ulnar groove plasty proximal to the cubital tunnel. The ulnar nerve was replaced into this reconstructed groove. The nerve was confirmed to be stable throughout the full range of elbow motion. The cubital tunnel retinaculum of all patients was hypoplastic and the dislocated portion of the ulnar nerves was hard. One nerve showed severe adhesion around the dislocation site. One patient had a pseudo-neuroma. All patients were relieved of discomfort, and motor and sensory function were recovered. The ulnar nerve in the groove showed neither irritation nor adhesion. In patients with grade 1, symptoms or numbness of the fingers was relieved within three months of the operation. Sensory disturbances in patients with grade 2 symptoms also improved within six months. Grade 2 patients with intrinsic muscle weakness regained normal muscular power, and these with patients with intrinsic muscle atrophy had showed increasing muscular power. The patient with grade 3 symptomes recovered normal sensation after 1 year; clawing of the ring and little fin-gers recovered, and the muscle volume was increased. Friction ulnar neuropathy has been treated traditionally by anterior transpositon or medial epicondylectomy. The ulnar nerve may become entrapped in scar tissue after these operations. We believe that this anatomical position is optimum for the nerve and that this procedure is essential for treatment of friction neuropathy

Certain technical advances, such as flexible intramedullary fixation and bioreabsorbable implants, have further increased enthusiasm for surgical management of pediatric fractures.» (Flynn et al.). In the Paediatric Surgery Department biodegradable pins of solid polydioxanone (PDS) in management of paediatric fractures have been used since April 1986. PDS pins are too soft for the osteosynthesis in fractures with fragments under high tensile pressures. However, we have successfully carried out a large number of internal fixations in children’s elbows. This is based on accurate distribution of PDS pins and careful positioning of periostal sutures and the adjacent disrupted muscles. Our technique, as presented at the 2nd European Congress of Paediatric Surgery in Madrid in 1997, is to fix temporarily the repositioned fractured fragment with Kirschner’s metal wire. Following osteosynthesis with PDS, the protruding K-wire is left in place for seven days until the limb is safely immobilized.

A total of 96 patients were operated. The purpose of the study is to compare osteosynthesis with PDS pins (Group A) with that of metallic K-wire (Group B). Each group consisted of 48 children. General characteristics (age, sex, and fracture types) were statistically the same (P > 0.05). In Group A, with children between 2 and 13 years, or 9.3 on average, 21 children were with the lateral condyle fractures (43.75%), 25 children with medial epicondyle fractures (52.08%), and 2 children with medial condyle fractures (4.16%). In Group B, with children between 2 and 14 years, or 8.7 on average, 26 children were with lateral condyle fractures (54.16%), 19 children with medial epicondyle fractures (39.58%), and 3 with medial condyle fractures (6.25%). The study excludes Milch Type II fractures of medial and lateral condyles. The results have been examined in the follow-up period of one, three, and six months of two different methods according to Flynn’s criteria. After statistical evaluation the differences obtained had no statistical significance (P > 0.05). However, satisfaction score (0 – 10) is significantly higher in Group A than in Group B for both parents and evaluators (P < 0.05). Both treatments exhibit good results with the exception that the use of metal osteosynthetic material requires another operation. If metal wires are used and cut just underneath the skin, protruding with local inflammation may appear. Proper use of PDS pins requires no further operation. This is to the benefit for both the patient and rehabilitation staff.

The objective of this study was to analyze the biomechanical effect of an implanted ACL graft by determining the tunnel position according to the aspect ratio (ASR) of the distal femur during flexion-extension motion. To analyze biomechanical characteristics according to the ASR of the knee joint, only male samples were selected to exclude the effects of gender and 89 samples were selected for measurement. The mean age was 50.73 years, and the mean height was 165.22 cm. We analyzed tunnel length, graft bending angle, and stress of the graft according to tunnel entry position and aspect ratio (ratio of antero-posterior depth to medio-lateral width) of the articular surface for the distal femur during single-bundle outside-in anterior cruciate ligament reconstruction surgery. We performed multi-flexible-body dynamic analyses with wherein four ASR (98, 105, 111, and 117%) knee models. The various ASRs were associated with approximately 1-mm changes in tunnel length. The graft bending angle increased when the entry point was far from the lateral epicondyle and was larger when the ASR was smaller. The graft was at maximum stress, 117% ASR, when the tunnel entry point was near the lateral epicondyle. The maximum stress value at a 5-mm distance from the lateral epicondyle was 3.5 times higher than the 15-mm entry position and, the cases set to 111% and 105% ASR, showed 1.9 times higher stress values when at a 5-mm distance compared with a 15-mm distance. In the case set at 98% ASR, the low-stress value showed a without-distance difference from the lateral epicondyle. Our results suggest that there is no relationship between the ASR and femoral tunnel length, A smaller ASR causes a higher graft bending angle, and a larger ASR causes greater stress in the graft

The posterior compartments of the knee are currently accessed arthroscopically through anterior, posteromedial or posterolateral portals. A direct posterior portal to access the posterior compartments has been overlooked due to a perceived high-risk of injury to the popliteal neurovascular structures. Therefore, this study aimed to investigate the safety and accessibility of a direct posterior portal into the knee. This cross-sectional study comprised a sample of 95 formalin-embalmed cadaveric knees and 9 fresh-frozen knees. Cannulas were inserted into the knees, 16mm from the vertical plane between the medial epicondyle of the femur and medial condyle of the tibia and 8 and 14mm (females and males respectively) from the vertical plane connecting the lateral femoral epicondyle and lateral tibial condyle. Landmarks were identified in full extension and cannula insertion was completed with the formalin-embalmed knees in full extension and the fresh-frozen in 90-degree flexion. Posterior aspects of the knees were dissected from superficial to deep, to assess potential damage caused by cannula insertion. Incidence of neurovascular damage was 9.6% (n=10); 0.96% medial cannula and 8.7% lateral cannula. The medial cannula damaged one small saphenous vein (SSV) in a male specimen. The lateral cannula damaged one SSV, 7 common fibular nerves (CFN) and both CFN and lateral cutaneous sural nerve in one specimen. All incidences of damage occurred in formalin-embalmed knees. The posterior horns of the menisci were accessible in all specimens. A medial-lying direct posterior portal into the knee is safe in 99% of occurrences. The lateral-lying direct posterior portal is of high risk to the CFN

Abstract. Introduction. Previous research has shown that, notwithstanding ligament healing, properly selected MCL reconstruction can restore normal knee stability after MCL rupture. The hypothesis of this work was that it is possible to restore knee stability (particularly valgus and AMRI) with simplified and/or less-invasive MCL reconstruction methods. Methods. Nine unpaired human knees were cleaned of skin and fat, then digitization screws and optical trackers were attached to the femur and tibia. A Polaris stereo camera measured knee kinematics across 0. o. -100. o. flexion when the knee was unloaded then with 90N anterior-posterior force, 9Nm varus-valgus moment, 5Nm internal-external rotation, and external+anterior (AMRI) loading. The test was conducted for the following knee conditions: intact, injured: transected superficial and deep MCL (sMCL and dMCL), and five reconstructions: (long sMCL, long sMCL+dMCL, dMCL, short sMCL+dMCL, short sMCL), all based on the medial epicondyle isometric point and using 8mm tape as a graft, with long sMCL 60mm below the joint line (anatomical), short sMCL 30mm, dMCL 10mm (anatomical). Results. No significant changes were found in anterior or posterior translation, or varus at any stage. MCL deficiency caused increased valgus, external rotation and AMRI instabilities. All reconstructions restored valgus stability. The isolated long sMCL allowed residual external rotation and AMRI instability, while the short sMCL did stabilise AMRI. Both 2-strand reconstructions (dMCL+sMCL) restored stability. Conclusion. All tested techniques, except long sMCL, restored valgus and AMRI stability of the knee. The single femoral tunnel is satisfactory for both the dMCL and sMCL grafts

A primary goal of revision Total Knee Arthroplasty (rTKA) is restoration of the Joint Line (JL) and Posterior Condylar Offsets (PCO). The presence of a native contralateral joint allows JL and PCO to be inferred in a way that could account for patient-specific anatomical variations more accurately than current techniques. This study assesses bilateral distal femoral symmetry in the context of defining targets for restoration of JL and PCO in rTKA. 566 pre-operative CTs for bilateral TKAs were segmented and landmarked by two engineers. Landmarks were taken on both femurs at the medial and lateral epicondyles, distal and posterior condyles and hip and femoral centres. These landmarks were used to calculate the distal and posterior offsets on the medial and lateral sides (MDO, MPO, LDO, LPO respectively), the lateral distal femoral angle (LDFA), TEA to PCA angle (TEAtoPCA) and anatomic to mechanical axis angle (AAtoMA). Mean bilateral differences in these measures were calculated and cases were categorised according to the amount of asymmetry. The database analysed included 54.9% (311) females with a mean population age of 68.8 (±7.8) years. The mean bilateral difference for each measure was: LDFA 1.4° (±1.0), TEAtoPCA 1.3° (±0.9), AAtoMA 0.5° (±0.5), MDO 1.4mm (±1.1), MPO 1.0mm (±0.8). The categorisation of asymmetry for each measure was: LDFA had 39.9% of cases with <1° bilateral difference and 92.4% with <3° bilateral difference, TEAtoPCA had 45.8% <1° and 96.6% <3°, AAtoMA had 85.7% <1° and 99.8% <3°, MDO had 46.2% <1mm and 90.3% <3mm, MPO had 57.0% <1mm and 97.9% <3mm. This study presents evidence supporting bilateral distal femoral symmetry. Using the contralateral anatomy to obtain estimates for JL and PCO in rTKA may result in improvements in intraoperative accuracy compared to current techniques and a more patient specific solution to operative planning

Abstract. Introduction. MCL injuries often occur concurrently with ACL rupture – most noncontact ACL injuries occur in valgus and external rotation (ER) - and conservative MCL treatment leads to increased rate of ACL reconstruction failure. There has been little work developing effective MCL reconstructions. Methods. Cadaveric work measured MCL attachments by digitisation and radiographically, relating them to anatomical landmarks. The isometry of the superficial and deep MCL (sMCL and dMCL) and posterior oblique ligament (POL) was measured using fine sutures led to displacement transducers. Contributions to stability (restraint) were measured in a robotic testing system. Two MCL reconstructions were designed and tested: 3-strand reconstruction (sMCL+dMCL+POL), and 2-strand method (sMCL+dMCL) addressing anteromedial rotatory instability (AMRI). The resulting stability was measured in a kinematics test rig, and compared to the ‘anatomic’ sMCL+POL reconstruction of LaPrade. Results. The sMCL was isometric, centred on the medial epicondyle, and the primary restraint of valgus. The dMCL elongated rapidly in ER, and was the primary restraint of ER near knee extension. The POL slackened rapidly with flexion and only stabilised the knee near extension. With sMCL+dMCL+POL deficiency (‘grade 3’), the 2-strand AM reconstruction restored all stability measures to native, apart from internal rotation. The 3-strand reconstruction restored all stability measures to native. The LaPrade reconstruction did not control ER, lacking a dMCL graft, or valgus in flexion, being anisometric. Conclusions. This work has revealed the importance of the dMCL in stabilising AMRI as part of anatomical MCL reconstruction, with the sMCL restraining valgus

The purpose of this study is to investigate the three-dimensional (3D) kinematics of normal knees in deep knee-bending motions like squatting and kneeling. Material & Methods: We investigated the in vivo kinematics of 4 Japanese healthy male volunteers (8 normal knees in squatting, 7 normal knees in kneeling). Each sequential motion was performed under fluoroscopic surveillance in the sagittal plane. Femorotibial motion was analyzed using 2D/3D registration technique, which uses computer-assisted design (CAD) models to reproduce the spatial position of the femur and tibia from single-view fluoroscopic images. We evaluated the femoral rotation relative to the tibia and anteroposterior (AP) translation of the femoral sulcus and lateral epicondyle on the plane perpendicular to the tibial mechanical axis. Student's t test was used to analyze differences in the absolute value of axial rotation and AP translation of the femoral sulcus and lateral epicondyle during squatting and kneeling. Values of P < 0.05 were considered statistically significant. During squatting, knees were gradually flexed from −2.8 ± 1.3° to 145.5 ± 5.1° on average. Knees were gradually flexed from 100.8 ± 3.9° to 155.6 ± 3.2° on average during kneeling. Femurs during squatting displayed sharp external rotation relative to the tibia from 0° to 30° of flexion and it reached 12.5 ± 3.3° on average. From 30° to 130° of flexion, the femoral external rotation showed gradually, and it reached 19.1 ± 7.3° on average. From 130° to 140° of flexion, it was observed additionally, and reached 22.4 ± 6.1° on average. All kneeling knees displayed femoral external rotation relative to the tibia sharply from 100° to 150° of flexion, and it reached 20.7 ± 7.5° on average. From 100° to 120° of flexion, the femoral external rotation during squatting was larger than that during kneeling significantly. From 120° to 140° of flexion, there was no significant difference between squatting and kneeling. The sulcus during squatting moved 4.1 ± 4.8 mm anterior from 0° to 60° of flexion. From 60° of flexion it moved 13.6 ± 13.4 mm posterior. The sulcus during kneeling was not indicated significant movement with the knee flexion. The lateral epicondyle during squatting moved 39.4 ± 7.7 mm posterior from 0° to 140° of flexion. The lateral epicondyle during kneeling moved 22.0 ± 5.4 mm posterior movement from 100° to 150° of flexion. In AP translation of the sulcus from 100° to 140° of flexion, there was no significant difference between squatting and kneeling. However in that of the lateral epicondyle, squatting groups moved posterior significantly. Even if they were same deep knee-bending, the kinematics were different because of the differences of daily motions. The results in this study demonstrated that in vivo kinematics of deep knee-bending were different between squatting and kneeling

Abstract. Objectives. Neonatal motor development transitions from initially spontaneous to later increasingly complex voluntary movements. A delay in transitioning may indicate cerebral palsy (CP). The general movement optimality score (GMOS) evaluates infant movement variety and is used to diagnose CP, but depends on specialized physiotherapists, is time-consuming, and is subject to inter-observer differences. We hypothesised that an objective means of quantifying movements in young infants using motion tracking data may provide a more consistent early diagnosis of CP and reduce the burden on healthcare systems. This study assessed lower limb kinematic and muscle force variances during neonatal infant kicking movements, and determined that movement variances were associated with GMOS scores, and therefore CP. Methods. Electromagnetic motion tracking data (Polhemus) was collected from neonatal infants performing kicking movements (min 50° knee extension-flexion, <2 seconds) in the supine position over 7 minutes. Tracking data from lower limb anatomical landmarks (midfoot inferior, lateral malleolus, lateral knee epicondyle, ASIS, sacrum) were applied to subject-scaled musculoskeletal models (Gait2354_simbody, OpenSim). Inverse kinematics and static optimisation were applied to estimate lower limb kinematics (knee flexion, hip flexion, hip adduction) and muscle forces (quadriceps femoris, biceps femoris) for isolated kicks. Functional principal component analysis (fPCA) was carried out to reduce kicking kinematic and muscle force waveforms to PC scores capturing ‘modes’ of variance. GMOS scores (lower scores = reduced variety of movement) were collected in parallel with motion capture by a trained operator and specialised physiotherapist. Pearson's correlations were performed to assess if the standard deviation (SD) of kinematic and muscle force waveform PC scores, representing the intra-subject variance of movement or muscle activation, were associated with the GMOS scores. Results. The study compared GMOS scores, kinematics, and muscle force variances from a total of 26 infants with a mean corrected gestational age of 39.7 (±3.34) weeks and GMOS scores between 21 and 40. There was a significant association between the SD of the PC scores for knee flexion and the GMOS scores (PC1: R = 0.59, p = 0.002; PC2: R = 0.49, p = 0.011; PC3: R = 0.56, p = 0.003). The three PCs captured variances of the overall flexion magnitude (66% variance explained), early-to-late kick knee extension (20%), and continual to biphasic kicking (6%). For hip flexion, only the SD of PC1 correlated with GMOS scores (PC1: R = 0.52, p = 0.0068), which captured the variance of the overall flexion magnitude (81%). For the biceps femoris, the SD of PC1 and PC3 associated with GMOS scores (PC1: R = 0.50, p = 0.002; PC3: R = 0.45, p = 0.03), which captured the variance of the overall bicep force magnitude (79%) and early-to-late kick bicep activation (8%). Conclusions. Infants with reduced motor development as scored in the GMOS displayed reduced variances of knee and hip flexion and biceps femoris activation across kicking cycles. These findings suggest that combining objectively measured movement variances with existing classification methods could facilitate the development of more consistent and accurate diagnostic tools for early detection of CP. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Several studies have described the relationship between the joint line and bony landmarks around the knee. However, high inter-patient variation makes these absolute values difficult in use. This study was set up to validate the previously described distances and ratios on calibrated full limb standing X-rays and to investigate the accuracy and reliability of these ratios as a tool for joint line reconstruction. Methods:. One hundred calibrated full-leg standing radiographs obtained from healthy volunteers were reviewed (fig 1). Distances from the medial epicondyle, the lateral epicondyle, the adductor tubercle, the fibular head and the proximal center of the knee (CJD) to the virtual prosthetic joint line were determined (fig 3). This prosthetic joint line was created by introducing a virtual distal femoral cutting block with a valgus angle of 6° on the full-leg radiographs. The adductor ratio was defined as the distance from adductor tubercle to the joint line divided by the femoral width. The correlation with the femoral width, the CJD and the limb alignment was analysed using linear regression analysis. The accuracy and reliability of the use of the ratio of the distance of the adductor tubercle, the medial epicondyle and the CJD relative to the femoral width to reconstruct the joint line was calculated. Results:. The average distance to the joint line from the medial epicondyle, the lateral epicondyle, the adductor tubercle and the fibular head was 28 mm (SD 2.97), 27 mm (SD 2.67), 44 mm (SD 4,27) and 15 mm (SD 3.69) respectively. The distance from the adductor tubercle (R = 0,82) and the CJD (R = 0,96) to the joint line showed a strong and significant linear correlation with the femoral width. The medial epicondyle, the lateral epicondyle and the fibular head showed less strong correlations. There was no significant correlation with the limb alignment. The adductor ratio was found to be 0.52 (SD 0.027) with only small inter-individual variation. The use of the adductor ratio reconstructed the joint line within 4 mm of its original level in 92% of the cases. Discussion. The absolute distances and ratios for determining joint line position as previously described, were confirmed on calibrated full-limb standing radiographs. Recently, the adductor tubercle has been described as a reliable landmark for determining joint line position. As a rule of thumb, the femoral width as measured on the preoperative radiograph or intra-operative, is divided by 2. Intra-operative, the distance from the adductor tubercle to the distal cutting block that has been inserted with a 6° distal cutting angle, is adjusted to equal the calculated value. Fixation of the cutting block at this level will automatically reconstruct the joint line at its original level (fig 2). Modern instrumentation techniques will allow you to immediately select the appropriate size distal femoral augment to reconstruct this joint level. Conclusion. The adductor ratio was found to be the most useful and accurate tool to restore the joint line to its original level in revision TKA

The accuracy of measurement in computer-assisted total knee arthroplasty is dependent on the quality of data acquisition at the start of the procedure; errors in landmark identification could lead to misalignment and therefore poorer longterm outcomes. Some navigation systems require the surgeon to explicitly identify the femoral epicondyles in order to calculate the trans-epicondylar axis, whereas other systems are able to interpolate the epicondylar location based on a number of points acquired from the distal femoral surface. Significant inter-observer variability in landmark identification has been previously reported in dry bone studies. The purpose of this study was to test the accuracy of identification of the epicondyles during a simulated total knee replacement on a fresh cadaveric specimen. An unfixed fresh cadaveric left lower limb was used to perform a navigated total knee replacement using the Orthopilot® (B|Braun-Aesculap, Tuttlingen, Germany) image-free navigation system. Sixteen surgeons attending an advanced navigation training course were invited to take part. A single consultant surgeon performed initial dissection and pin placement, up to the point of landmark acquisition. Each subject was then asked to use a pointer tool to identify the medial and lateral epicondyles, as they would in an operative situation. Data were recorded by the Orthopilot® system, and exported as a 3D array for further analysis. Initial visualisation with a 3D scatter plot showed that points were evenly distributed within a circular pattern around each epicondyle. The length of a vector between each point on each epicondyle was calculated in turn. The maximum distances between points were 15.6mm for the medial epicondyle, and 19.9mm for the lateral epicondyle. We then calculated the length and angulation of the trans-epicondylar axis (TEA) for each observer, equivalent to the vector between each pair of points (medial and lateral epicondyle). An average TEA was calculated, and the range and standard deviation of angulation were determined. In the x axis the range was 16.3° (–8.3° to 7.9°, SD 5.1°), in the y axis the range was 18.7° (–8.7° to 10°, SD 5.2°) and in the z axis the range was 20.5° (–10.1° to 10.4°, SD 6.5°). Range of recorded TEA length was 64.5 to 74.9mm (mean 70.6mm, SD 3.3mm). We conclude that in this simulated operative scenario, surgeons exhibited considerable variability when locating the epicondyles. Range of angulation of the TEA exceeded 16° (SD > 5.1°) in all 3 planes. We cannot recommend the use of a trans-epicondylar axis determined from 2 single points, as a reliable landmark in navigated total knee replacement

Introduction: The epicondylar axis is often cited as a guide to rotation of the femoral component in total knee arthroplasty. Our aimwas to accurately identify with digital palpation, the epicondyles in 14 cadaveric knees Method: Each cadaveric knee had a midline parapatellar approautil ch and the patella was everted. The epicondyles where palpated and the position of the epicondyles was marked by inserting a pin in each epicondyle. All cadavers had a CT scan to identify the position of the epicondyles and pins. The angular difference was calculated with computer-guided measurements. Results: Of the seven right knees, þve had perfect epicondylar identiþcation, whilst two had inaccurate placement of pins. In both cases of error the medial epicondyle had a sulcus conþguration as opposed to a prominent ridge. This resulted in internal rotation of 2 degrees and 3 degrees. Of the seven left knees, þve had perfect epicondylar identiþcation, whilst two had inaccurate pin placement. In both cases this was inaccurate placement of the medial epicondylar pin in a sulcus conþguration. In both this resulted in extra external rotation of the component to 6 degrees. Overall four out of 14 knees had inaccurate placement and in each the medial epicondyle had a sulcus conþguration

Incorrect registration during computer assisted total knee arthroplasty (CA-TKA) leads to malposition of implants. Our aim was to evaluate the tolerable error in anatomic landmark registration. We incorrectly registered the femoral epicondyles, femoral and tibial centers, as well as the malleoli and documented the change in angulation or rotation. We found that the distal femoral epicondyles were the most difficult anatomic landmarks to register. The other bony landmarks were more forgiving. Identification of the distal femoral epicondyles has a high inter- and intra-observer variability. Our observation that there is less than 2 mm of safe zone in the anterior or posterior direction during registration of the medial and lateral epicondyles may explain the inability of CA-TKA to improve upon the outcomes of conventional TKA

Introduction. Component position and overall limb alignment following Total Knee Arthroplasty (TKA) have been shown to influence device survivorship and clinical outcomes. However current methods for measuring post-operative alignment through 2D radiographs and CTs may be prone to inaccuracies due to variations in patient positioning, and certain anatomical configurations such as rotation and flexion contractures. The purpose of this paper is to develop a new vector based method for overall limb alignment and component position measurements using CT. The technique utilizes a new mathematical model to calculate prosthesis alignment from the coordinates of anatomical landmarks. The hypothesis is that the proposed technique demonstrated good accuracy to surgical plan, as well as low intra and inter-observer variability. Methods. This study received institutional review board approval. A total of 30 patients who underwent robotic assisted TKA (RATKA) at four different sites between March 2017 and January 2018 were enrolled in this prospective, multicenter, non-randomized clinical study. CT scans were performed prior to and 4–6 weeks post-operatively. Each subject was positioned headfirst supine with the legs in a neutral position and the knees at full extension. Three separate CT scans were performed at the anatomical location of the hip, knee, and ankle joint. Hip, knee, and ankle images were viewed in 3D software and the following vertices were generated using anatomical landmarks: Hip Center (HC), Medial Epicondyle Sulcus (MES), Lateral Epicondyle (LE), Femur Center (FC), Tibia Center (TC), Medial Malleolus (MM), Lateral Malleolus (LM), Femur Component Superior (FCS), Femur Component Inferior (FCI), Coronal Femoral Lateral (CFL), Coronal Femoral Medial (CFM), Coronal Tibia Lateral (CTL), and Coronal Tibia Medial (CTM). Limb alignment and component positions were calculated from these vertices using a new mathematical model. The measurements were compared to the surgeons’ operative plan and component targeted positions for accuracy analysis. Two analysts performed the same measurements separately for inter-observer variability analysis. One of the two analysts repeated the measurements at least 30 days apart to assess intra-observer variability. Correlation analysis was performed on the intra-observer analysis, while Bland Altman analysis was performed on the inter-observer analysis. Results. Average measurement errors of overall limb alignments, femoral and tibial component position were less than 1 degree. Bland Altman plots for inter-observer analysis demonstrate great reproducibility in limb and component alignment measurements between surgeons with no bias. Correlation plots for intra-observer analysis demonstrate low variability with slopes ranging between 0.86 to 1.00 and R value greater than 0.88. Discussion. The proposed method demonstrated good accuracy to plan and low intra- and inter observer variability. This technique may be considered for assessing component position accuracy with post-operative CTs. Further studies are needed to investigate the robustness of the method in a larger cohort. For any figures or tables, please contact authors directly

Introduction: Rotational alignment of femoral component in TKA affect the clinical results of long-term follow up (Stiehl). Improper alignment may lead to unstable femoro-tibial joint, to wear or loosening of tibial component, and is associated with the subluxation or dislocation of the patella by patella-femoral mal-tracking (Pascal 1996). The precise setting of femoral component is important for the smooth patella tracking and good ligament balancing in TKA. Previously orientation of rotation of the femoral component has been set by equal resection of the posterior condyle (Hungerford 1985, Laskin 1989). The anteroposterior axis of the distal femur that was defined by a line through the deepest part of the patellar groove anteriorly and the center of the intercondylar notch posteriorly, was an easy and reliable landmark of the rotational alignment of the femoral component (Whiteside, Arima). The posterior condylar line (PC line) that connects the posterior condyle of the femur is widely used as a landmark for the cutting of the posterior condyle. Also, 3°external rotation off the posterior femoral condyle has been commonly used as a intraoperative landmark (Laskin1995). The anatomical and functional axis of the femur has been studied so far (Poilvache.Yoshioka1987). Transepicondylar axis (TEA) as the origin of collateral ligament is valuable axis for the parallel cut of the posterior condyle (Berger, Miller). TEA was found to be a reliable landmark to proper rotation of the femoral component, measuring the angle between the axis and the posterior condylar line to orient the femoral component is very important. However, intra-operative manual palpation of the TEA was not reproducible because most prominent point was covered with soft tissue (Jenny). It is sometimes difficult to identify the sulcus of the medial epicondyle accurately with palpation even during surgery (). Therefore, it is crucial to measure and evaluate the TEA as the preoperative planning. The posterior condylar line (PC line) that connects the posterior condyle of the femur is also used for the landmark of the cutting of the posterior condyle. The methods of examining the angle between TEA and PC line are computed tomography (CT) and kneeling view that was simple radiographic technique by Takai et al. Posterior condyle of deformed side makes inaccurate decision of the angle for TEA and PC line because thickness of cartilage and bone are different between medial and lateral condyle. PCA is not applicable in MIS-TKA because it is very difficult to visualize the posterior condyle in the lateral side by the medial approach. Alternative landmark of the angle between TEA and anterior trochlear line of lateral and medial femoral condyles for the determination of rotational positioning of the femoral component may be considered. We have improved the simple radiographic view of evaluating the TEA and PC line but also anterior trochlear line for the assessment of rotational alignment of the distal femur in TKA. The purpose of this study was to measure these angles and to evaluate the reliabilities in compared with 3D-CT. Subjects and methods Our new radiograph we describe is the antero-posterior view of looked-up distal femur. The patient lies on the supine position and flexes the knee about 130 degrees as much as possible. X-ray is applied to the knee at the right angle to the front of the skin from 20 degrees bottom (Figure 1). We pointed out the location of the anterior surface of the condyles, medial epicondyle and lateral epicondyle. We marked the medial and lateral epicondyle of anterior surface of condyles, and posterior condyles as the indivisual reference points in these views. We defined the anterior intercondylar line (trochlear line) as the most axial projections of the medial and lateral femoral condyles. We defined PC line as a line connecting the surfaces of the subarticular cortex of the medial and lateral posterior femoral condyles likewise. We used to obtain clinical TEA that was defined by drawing the most prominent points of the medial and lateral epicondyles. We measured the external rotational angle between PC line and clinical TEA (condylar twist angle), and the internal rotational angle between clinical TEA and trochlear line (Figure 2). Reproducibility of our radiographic technique We examined the reproducibility of our new radiographical technique by 20 healthy volunteers. They included ? males and ? females and the average age of the patients was # years (# ~ # years). No knees in volunteers showed remarkable deformities. We photographed at the flexion angle from 110 to 140 degrees every 10 degrees, at the incident angle of 20 and 30 degrees. The anterior trochlear line, PC line and clinical TEA were drawn on the images and measured condylar twist angle and the internal rotation angle between clinical TEA and trochlear line. The differences of their measurements were quantified using paired t-test. Comparison with our view and reconstruction images of 3-dimensional helical CT system The CT images of 35 knee joints in 28 patients had been taken at full extension of the knee using 512 × 512 pixel matrix, in addition of plain X-ray. From the data of CT images, two different images were acquired such as the composition images and the reconstruction images of 3D. The composition images were obtained by putting a photograph with slices of every 2 mm on top of one another. The CT slices (Shimazu Co Ltd, Kyoto, Japan) obtained from the proximal edge of the patella to the joint line of the knee. We added anterior surface of condyles, medial epicondyle, lateral epicondyle and posterior condyles on tracing paper every slice in the same place. Then we drawn trochlear line, PC line and clinical TEA, and measured the external rotation angle between PC line and clinical TEA (condylar twist angle) and the internal rotation angle between clinical TEA and trochlear line. The reconstruction images were obtained by the distal femoral view looked-up from distal aspect and reconstructed with 3-dimensional helical CT system. We have drawn trochlear line, PC line, clinical TEA, and measured the external rotation angle between PC line and clinical TEA (condylar twist angle), and the internal rotation angle between clinical TEA and trochlear line from three methods mentioned above and had compared them. The differences of their measurements were compared with three groups. This study involved 122 knees in 82 patients including 22 males and 80 females with osteoarthritis of the knee. The average age of the patients was 67.3 years from 37 to 89 years. We classified by Kellgren and Lawrence classification (K-L grade). They consisted of grade 1; 12 knees, grade 2; 37 knees, grade 3; 34 knees, and grade 4; 39 knees. Tibiofemoral angle (TFA) on long-leg radiography at the standing position were ranged from 164°to 197°; mean, 180.2°±6.7°. We examined the correlation between condylar twist angle and gender, TFA, height and weight. Informed consent. Statistics: Statistical analysis was performed on a personal computer using a statistical software of Statview (SAS institute, Chicago, IL). P values of less than.05 was considered as statistically significant. We used the t-test, which does not need the raw data, to compare our results with those published. We were able to obtain information on the number of subjects (to calculate the degree of freedom) and the mean from the publications. Results: The external rotation angle between PC line and clinical TEA (PC-TEA), that is condylar twist angle (CTA) was 5.6°±2.8°(mean±s.d). The internal rotational angle between clinical TEA and anterior trochlear line (trochlear-TEA) was 5.7°±3.2°. K-L grade was negatively correlated with these rotational angles using Kruskal Wallis test (Table 1). These angles of female was larger than those of male (Table 2). The varus angle was negatively correlated with the CTA (R=−0.30) and positively correlated with the internal rotation angle of trochlear-TEA (R=0.376) (Figure 3). The external rotation angle between PC line and clinical TEA was 5.3°±2.4° at our view, and 5.5°±2.3° at reconstruction images from 3-dimensional helical CT system. The difference of condylar twist angle between plain X-ray and 3D-CT was shown in Figure 4. The internal rotation angle between clinical TEA and anterior trochlear line was 5.3°±2.4° at our view, °and 5.7°±2.3° at reconstruction images from 3-dimentional helical CT system. The difference of the internal rotation angle between clinical TEA and anterior trochlear line between plain X-ray and 3D-CT was shown in Figure 5. Regarding the reproducibility about the flexion angle of the knee and the incident angle, correlation coefficients were ? for the flexion angle of the knee, ? for the incident angle. All cases were within 5° variations of the external rotation angle between PC line and clinical TEA, and 4° variations of the internal rotation angle between clinical TEA and trochlear line, respectively. The case of at 110° flexion and 30° incident angle, however, tends to be more variable than the other cases due to unclear PC line (SD 3.3°; range 3–16°). Discussion: Two kinds of TEAs are used for the reference of femoral rotation on the surgical TEA and the clinical TEA. Surgical TEA is a line connecting the sulcus of the medial epicondyle and the lateral epicondylar prominence (Berger 1993). The posterior condylar angle (PCA) is the angular measurement subtended by the surgical TEA and the posterior condylar line (PCL). The clinical TEA is a line connecting the medial and lateral epicondylar prominence. Clinical twist angle (CTA) is the angular measurement subtended by the clinical TEA and the PCL. The most prominent point of the medial epicondyle that is a landmark of CTA was much better identifiable than the medial sulcus for the landmark of PCA (Suter 2006). The sulcus of the medial epicondyle could only be identified in 53 % of the CT images, however, the most prominent point of the medial epicondyle in CT images was clearly discernible in all knees (Suter 2006). Yoshino et al. recommended the use of the CTA in planning for TKA. Even during surgery the determination of the sulcus is difficult by the palpation (). Medial sulcus become obscures in the severely deformed osteoarthritic knee (Yoshino). . Intra-operative palpation of the trans-epicondylar axis involved a mean of 5° intra- and inter-observer variations (Jenny 2004). Some authors reported that CTA was 3.6° ± 2.02, 3.58° in male and 3.62° in female during TKA (Poilvache), however, in CT study. Arima reported that CTA was 5.7°± 1.7, in cadaver study 4.4° in male and 6.4° in female. In our study, there was significant difference in gender of CTA. There has been only a few reports regarding the angle between the TEA and anterior trochlear line of the lateral and medial femoral condyles (trochleo-epicondylar angle). The line between the most anterior projections of the lateral and medial femoral condyle was called as trochlear line, was measured (Poilvache 1996), trochleo-epicondylar (surgical) angle was 4.95° ± 2.15, 4.4° in male, 5.38° in female during TKA. The mean value of the trochleo-epicondylar angle in CT view was 8.0°± 1.76 of internal rotation in all subjects, 8.8° in male, 7.3° in female, there was significant gender difference (Won). Our developed view is the first method of showing the trochleoepicondylar angle in plain radiography. Our results demonstrated trochleo-epicondylar angle using clinical epicondylar axis was 5.6° ± 2.85 of internal rotation in all subjects, 5.27° in male, 5.77° in female, there was no significant gender difference. Line drawing of posterior condylar line between medial and lateral condyle in osteoarthritic knee sometimes make error of the angle measurement because thickness of cartilage and wear of subchondral bone is not equal in the both side of the condyle. Our view is the first method that is able to examine both the CTA and trochleo-epicondylar angle simultaneously, simple, need not to use special instrument, and reveal reproducible. A minimally invasive operative method in TKA is reported to be effective and recommended in primary OA. However, the reference guide of the angle between PCA and TEA is sometimes difficult to set properly with the full contact of both condyles in the limited view of the non-open side, especially MIS TKA. In contrast, it is easy to set the guide or template properly for the trochlear line angle during the surgery because the anterior trochlear is completely visible. Surgeons should not use only one method of femoral rotational alignment and make appropriate adjustment in TKA (Olcott 2000). Then, we focused on the angle between the anterior trochlear line and TEA,. And we developed the simple method of the radiographic view that is able to evaluate the trochlear line and clinical epicondylar axis as the preoperative surgical planning. From our data, the trochlear line angle with a landmark of the anterior femoral condyle by our radiographic view was reproducible. Our method may be a possible one for determining the rotational alignment of the femoral component in total knee arthroplasty. Regarding the study of variability of these angles in several kinds of flexion angle of the knee and . Therefore, we are able to measure and evaluate both angles, and reduce the measurement error by double-checking the conventional CTA and trochlear line angle

Summary. There is tremendous variability amongst surgeons' ability to reference anatomic landmarks. This may suggest the necessity of other objective methods in determining femoral alignment and rotation. Introduction. Despite the durability of total knee arthroplasty, there is much room for improvement with regards to functional outcome and patient satisfaction. One important factor contributing to poor outcomes after TKA is malrotation of the femoral component. It has been postulated that this is due to failure of surgeons to correctly reference bony landmarks, principally the femoral epicondyles, however, this is unproven. The purpose of this study was to evaluate the accuracy of joint surgeons and trainees in identifying anatomic landmarks for positioning the femoral component and to determine the effect of prior training and experience. Methods. 23 surgeons (17 attending surgeons, 6 trainees) participated in this study. Using custom-made computer software, each surgeon interactively defined the epicondylar axis (EA), the anterior-posterior axis (AP) of the distal cut (Whiteside's Line) on 3D computer models of 10 normal femora reconstructed from CT scans. Each surgeon then aligned a standard distal cutting guide on the resected distal surface of each femoral model. A standardized procedure was employed to determine the true location of the epicondyles, the direction of Whiteside's Line and the orientation of the cutting guide. Each participant was surveyed to ascertain their extent of formal training in joint arthroplasty, their annual volume of TKA cases, and whether they routinely aligned their TKAs using Whiteside's and the transepicondylar axis. The difference between the ideal and surgeon-selected parameters were calculated and correlated with data describing each surgeon's training and experience. Results. Landmark selection and guide placement was highly variable between surgeons. Overall, surgeons placed Whiteside's line in 1.83°± 7.01° of internal rotation vs. the calculated axes. Additionally, surgeons placed the transepicondylar axis in 1.40°± 3.72° of internal rotation vs. the calculated axes. On average, the guide was placed in 1.44°± 2.59° of additional internal rotation in comparison to the selected transepicondylar axis. Surgeons who routinely utilized the transepicondylar axis intraoperatively placed the guide significantly closer to the selected transepicondylar axis than those who did not (0.74°± 1.28° vs. 1.85°± 3.05°, p=.0024). Surprisingly, fellowship training, years of training, and volume of cases per year had no statistical effect the outcome of placement. Conclusion. This study suggests that there is tremendous variability amongst surgeons' ability to accurately reference the femoral epicondyles, Whiteside's line, and the transepicondylar axis. Our results also indicate that surgeons are not able to identify Whiteside's line with sufficient reliability for it to be a dependable indicator of correct component alignment in TKA. Our data also support the use of other methods to reliably determine correct rotational alignment of the femoral component in total knee arthroplasty