Intraoperative range of motion (ROM) radiographs are routinely taken during scaphoidectomy and four corner fusion surgery (S4CF) at our institution. It is not known if intraoperative ROM predicts postoperative ROM. We hypothesize that patients with a greater intra-operativeROM would have an improved postoperative ROM at one year, but that this arc would be less than that achieved intra- operatively. We retrospectively reviewed 56 patients that had undergone S4CF at our institution in the past 10 years. Patients less than 18, those who underwent the procedure for reasons other than arthritis, those less than one year from surgery, and those that had since undergone wrist arthrodesis were excluded. Intraoperative ROM was measured from fluoroscopic images taken in flexion and extension at the time of surgery. Patients that met criteria were then invited to take part in a virtual assessment and their ROM was measured using a goniometer. T-tests were used to measure differences between intraoperative and postoperative ROM, Pearson Correlation was used to measure associations, and linear regression was conducted to assess whether intraoperative ROM predicts postoperative ROM. Nineteen patients, two of whom had bilateral surgery, agreed to participate. Mean age was 54 and 14 were male and 5 were male. In the majority, surgical indication was scapholunate advanced collapse; however, two of the participants had scaphoid nonunion advanced collapse. No difference was observed between intraoperative and postoperative flexion. On average there was an increase of seven degrees of extension and 12° arc of motion postoperatively with p values reaching significance Correlation between intr-operative and postoperative ROM did not reach statistical significance for flexion, extension, or arc of motion. There were no statistically significant correlations between intraoperative and postoperative ROM. Intraoperative ROM radiographs are not useful at predicting postoperative ROM. Postoperative extension and arc of motion did increase from that measured intraoperatively

Aims. It has been well documented in the arthroplasty literature that lumbar degenerative disc disease (DDD) contributes to abnormal spinopelvic motion. However, the relationship between the severity or pattern of hip osteoarthritis (OA) as measured on an anteroposterior (AP) pelvic view and spinopelvic biomechanics has not been well investigated. Therefore, the aim of the study is to examine the association between the severity and pattern of hip OA and spinopelvic motion. Methods. A retrospective chart review was conducted to identify patients undergoing primary total hip arthroplasty (THA). Plain AP pelvic radiographs were reviewed to document the morphological characteristic of osteoarthritic hips. Lateral spine-pelvis-hip sitting and standing plain radiographs were used to measure sacral slope (SS) and pelvic femoral angle (PFA) in each position. Lumbar disc spaces were measured to determine the presence of DDD. The difference between sitting and standing SS and PFA were calculated to quantify spinopelvic motion (ΔSS) and hip motion (ΔPFA), respectively. Univariate analysis and Pearson correlation were used to identify morphological hip characteristics associated with changes in spinopelvic motion. Results. In total, 139 patients were included. Increased spinopelvic motion was observed in patients with loss of femoral head contour, cam deformity, and acetabular bone loss (all p < 0.05). Loss of hip motion was observed in patients with loss of femoral head contour, cam deformity, and acetabular bone loss (all p < 0.001). A decreased joint space was associated with a decreased ΔPFA (p = 0.040). The presence of disc space narrowing, disc space narrowing > two levels, and disc narrowing involving the L5–S1 segment were associated with decreased spinopelvic motion (all p < 0.05). Conclusion. Preoperative hip OA as assessed on an AP pelvic radiograph predicts spinopelvic motion. These data suggest that specific hip osteoarthritic morphological characteristics listed above alter spinopelvic motion to a greater extent than others. Cite this article: Bone Joint J 2023;105-B(5):496–503

The function of the shoulder joint has traditionally been evaluated based on range of motion (ROM) in predefined anatomical planes and also by using functional scores, which assessed shoulder function based on the ability to conduct certain activities of daily living (ADLs). However, measuring ROM only in terms of flexion-extension, abduction-adduction and internal-external rotation may under-account for the 3-dimensional mobility of the shoulder joint. Furthermore, functional scores, such as the Oxford shoulder score or American shoulder and elbow surgeons (ASES) score, are subjective measures and are not an accurate assessment of shoulder joint function. In this study, we proposed the use of the globe model of the shoulder joint which can be used to provide an objective measure of the global ROM and also function of the shoulder joint – termed the Global and Functional arc of motion (GAM and FAM). Thirty-three young, healthy male patients (23.7 ± 1.5 years) were recruited and tasked to perform eight ADLs and a full humeral circumduction movement which represented their active global ROM. Reflective markers were placed in accordance to the International Society of Biomechanics (ISB) and optical-based motion capture cameras were used to track relative motion of the dominant humerus with respect to the thorax (i.e. thoracohumeral motion). The GAM and FAM were generated by plotting the thoracohumeral on a spherical coordinate system during global ROM and the eight ADLs respectively. Shoulder joint global ROM and function were quantified by calculating the area enclosed by the closed loop of GAM and FAM respectively. The spherical coordinate system, or more commonly referred to as the globe model, describes thoracohumeral movement using plane of elevation (POE), angle of elevation (AOE) and rotation. In our model, POE and AOE represents longitude and latitude of the globe respectively, and rotation is depicted using a red-green-blue (RGB) colour scale. Overall, subject's GAM of the shoulder joint covered an area of 4.64 ± 0.48 units2 compared to only 1.12 ± 0.26 units2 for the FAM. Subjects only required 24.4 ± 5.7 % of their global shoulder ROM for basic daily functioning. Studies that reduced shoulder joint movement into planar movements (i.e. sagittal, coronal and rotation) do not account for the 3-dimensional nature of the joint and doing so may overestimate the requirement of the shoulder joint for ADLs relative to its ROM in each plane. While others have attempted to use the globe model, such studies tend to reduce the globe into its descriptive angles (i.e. POE, AOE and rotation), reducing its intuitiveness. In contrast, by keeping an intact globe, the proposed globe model was more intuitive and yet capable of quantifying both shoulder joint global ROM and function. Doing so, we found that young healthy subjects only required approximately a quarter of their global ROM of the shoulder joint to complete the most common daily tasks, which was significantly less than what was previously reported

Background:. Few clinical hip score include toe-reach motion after THA (put-on-socks, nail-cutting). Some reports have shown whether THA patients can put on socks or not in daily activity, and not shown how they can do it. The purpose of this study is to investigate real pattern of put-on-socks motion in daily activities after THA, and to evaluate safe range of motion for prevention of hip dislocation. Materials and Methods:. Reviewing clinical chart, we investigated highly frequent pattern in wearing socks motion that would cause hip dislocation in ADL in 100 patients with normal lower extremities except for hip joint more than one year after THA, then, we classified the motion pattern. Using an optical 3-D motion analysis (MAC3D system, Motion Analysis, USA), we measured necessary angle of the hip in 10 THA subjects (mean age at operation 61 years old) one year postoperatively, while the patients make such frequent patterns of movement as above. Simultaneously, individual 3-dimensional skeletal model was reconstructed from CT data and implant CAD data. Driving 3-D skeletal model combined with motion analysis data on display (Zed Hip, LEXI), we calculated angle from posture that hip flexion angle was maximum during wearing-socks motion to impingement point (implant and/or bone) for each direction. ALL joint angle was defined as “zero” in supine position. Results:. Resulting from clinical chart, high incident pattern of the motion was “Leg raising pattern” (26%), and “Trunk flexion pattern” (23%) (Figure 1). For above two pattern of the socks-wearing motion, 3-D motion analysis showed that maximum hip flexion angle was 85 ± 13 degrees for leg raising pattern, 88 ± 14 degrees for trunk flexion pattern. Hip angle of abduction/adduction or external/internal rotation was within mean 15 degrees during each motion. 3-D model simulation combined with motion data showed that 39 ± 15 degrees, 33 ± 9.7 degrees for direction of hip flection, 34 ± 17 degrees, 32 ± 11 degrees for direction of hip adduction and 78 ± 21 degrees, 51 ± 21 degrees for direction of hip internal rotation from posture on maximum hip flexion angle to impingement point for each motion, respectively. All cases showed safe range of more than 20 degrees for all direction and impingement occurred between cup and stem in all cases (Figure 2, 3). Discussion:. Recently, there have been trend to decrease limitation of motion in ADL after THA. Safe range of motion without impingement have been enlarged resulting from development of implant design, proper alignment and operative technique. This study showed safe range without impingement in frequent socks-wearing pattern in daily living among THA patients one year after surgery. More research for motion in ADL can lead to remove postoperative restrictions in THA patients

For many years, marker-based systems have been used for motion analysis. However, the emergence of new technologies, such as 4D scanners provide exciting new opportunities for motion analysis. In 4D scanners, the subjects are measured as a dense mesh, which enables the use of shape analysis techniques. In this talk, we will explore how the combination of the rising new motion analysis methods and shape modelling may change the way we think about movement and its analysis

Assessing the efficacy of cervical orthoses in restricting spinal motion has historically proved challenging due to a poor understanding of spinal kinematics and the difficulty in accurately measuring spinal motion. This study is the first to use an 8 camera optoelectronic, passive marker, motion analysis system with a novel marker protocol to compare the effectiveness of the Aspen, Aspen Vista, Philadelphia, Miami-J and Miami-J Advanced collars. Restriction of cervical spine motion was assessed for physiological and functional range of motion (ROM). Nineteen healthy volunteers (12 female, 7 male) were fitted with collars by an approved physiotherapist. ProReflex (Qualisys, Sweden) infra-red cameras were used to track the movement of retro-reflective marker clusters attached to the head and trunk. 3-D kinematic data was collected from uncollared and collared subjects during forward flexion, extension, lateral bending and axial rotation for physiological ROM and during five activities of daily living (ADLs). ROM in the three clinical planes was analysed using the Qualisys Track Manager (Qualisys, Sweden) 6 Degree of Freedom calculation to determine head orientation relative to the trunk. For physiological ROM, the Aspen and Philadelphia were more effective at restricting flexion/extension than the Vista (p<0.001), Miami-J (p<0.001 and p<0.01) and Miami-J Advanced (p<0.01 and p<0.05). The Aspen was more effective at restricting rotation compared to the Vista (p<0.001) and Miami-J (p<0.05). The Vista was least effective at restricting lateral bending (p<0.001). Through functional ROM, the Vista was less effective than the Aspen (p<0.001) and other collars (p<0.01) at restricting flexion/extension. The Aspen and Miami-J Advanced were more effective at restricting rotation than the Vista (p<0.01 and p<0.05) and Miami-J (p<0.05). All the collars were comparable when restricting lateral bending. The Aspen is superior to, and the Aspen Vista inferior to, the other collars at restricting cervical spine motion through physiological ROM. Functional ROM observed during ADLs are less than those observed through physiological ROM. The Aspen Vista is inferior to the other collars at restricting motion through functional ROM. The Aspen collar again performs well, particularly at restricting rotation, but is otherwise comparable to the other collars at restricting motion through functional ranges

Aims. Optimal glenoid positioning in reverse shoulder arthroplasty (RSA) is crucial to provide impingement-free range of motion (ROM). Lateralization and inclination correction are not yet systematically used. Using planning software, we simulated the most used glenoid implant positions. The primary goal was to determine the configuration that delivers the best theoretical impingement-free ROM. Methods. With the use of a 3D planning software (Blueprint) for RSA, 41 shoulders in 41 consecutive patients (17 males and 24 females; means age 73 years (SD 7)) undergoing RSA were planned. For the same anteroposterior positioning and retroversion of the glenoid implant, four different glenoid baseplate configurations were used on each shoulder to compare ROM: 1) no correction of the RSA angle and no lateralization (C-L-); 2) correction of the RSA angle with medialization by inferior reaming (C+M+); 3) correction of the RSA angle without lateralization by superior compensation (C+L-); and 4) correction of the RSA angle and additional lateralization (C+L+). The same humeral inlay implant and positioning were used on the humeral side for the four different glenoid configurations with a 3 mm symmetric 135° inclined polyethylene liner. Results. The configuration with lateralization and correction of the RSA angle (C+L+) led to better ROM in flexion, extension, adduction, and external rotation (p ≤ 0.001). Only internal rotation was not significantly different between groups (p = 0.388). The configuration where correction of the inclination was done by medialization (C+M+) led to the worst ROM in adduction, extension, abduction, flexion, and external rotation of the shoulder. Conclusion. Our software study shows that, when using a 135° inlay reversed humeral implant, correcting glenoid inclination (RSA angle 0°) and lateralizing the glenoid component by using an angled bony or metallic augment of 8 to 10 mm provides optimal impingement-free ROM. Cite this article: Bone Jt Open 2024;5(10):851–857

Introduction. Today, there is no clear consensus as to the amplitude of movement of the “normal hip”. Knowing the necessary joint mobility for everyday life is important to understand different pathologies and to better plan their treatments. Moreover, determining the hip range of motion (ROM) is one of the key points of its clinical examination. Unfortunately this process may lack precision because of movement of other joints around the pelvis. Our goal was to perform a preliminary study based on the coupling of MRI and optical motion capture to define precisely the necessary hip joint mobility for everyday tasks and to assess the accuracy of the hip ROM clinical exam. Methods. MRI was carried out on 4 healthy volunteers (mean age, 28 years). A morphological analysis was performed to assess any bony abnormalities. Two motion capture sessions were conducted: one aimed at recording routine activities (stand-to-sit, lie down, lace the shoes while seated, pick an object on the floor while seated or standing) known to be painful or prone to implant failures. During the second session, a hip clinical exam was performed successively by 2 orthopedists (2 and 12 years' experience), while the motion of the subjects was simultaneously recorded (Fig.1). These sequences were captured: 1) supine: maximal flexion, maximal IR/ER with hip flexed 90°, maximal abduction; 2) seated: maximal IR/ER with hip and knee flexed 90°. A hand held goniometer was used by clinicians to measure hip angles in those different positions. Hip joint kinematics was computed from the markers trajectories using a validated optimized fitting algorithm which accounted for skin motion artifacts (accuracy: translational error≍0.5 mm, rotational error <3°). The resulting computed motions were applied to patient-specific hip joint 3D models reconstructed from their MRI data (Fig. 2). Hip angles were determined at each point of the motion thanks to two bone coordinate systems (pelvis and femur). The orthopedist's results were compared. Results. All subject's hips were morphologically normal. For all movements, a minimum of 95° hip flexion was required (mean range 95°–107°), lacing the shoes and lying down being the more demanding. Abduction/adduction and IR/ER remained low (± 20°) and variable across subjects. Regarding the clinical exam, the error made by the clinicians varied in the range of ± 10°, except for the flexion and abduction where the error was higher (flexion: mean 9.5°, range −7°–22°; abduction: mean 19.5°, range: 8–32°). No significant differences between the errors made by the two examiners were noted (mean error for each examiner: 7.4° vs. 8.4°). Conclusion. Daily activities of a “normal hip” involve intensive hip flexion, which could explain why such motion can yield hip pain or possible implant failure. This information should be considered in the surgical planning and prosthesis design when restoring patient mobility and stability. The clinical exam seems to be a precise method for determining hip passive motion, if extra care is taken to stabilize the pelvis during flexion and abduction to prevent overestimation of the ROM. Further studies including more subjects are required before attesting the accuracy of this test

Body motion tracking for kinematic study is typically done with optical sensors. The user wears markers and the cameras track them to compute the transformation of the motion frame by frame. This method requires a set up of multiple motion capturing cameras and it can only be done within the specific area. The goal of this project is to create a tracking unit that does not require expensive overhead and can be done in any location. The advancement in micro-machined microelectromechanical system (MEMS) sensors such as accelerometer, gyroscope and magnetometers can be used for human motion tracking. The unit is attached to a body segment or an external housing unit such as a knee brace. The orientation of the unit can be calculated based on the data from all 3 of the sensors. A complementary filter is used to fuse the data together to generate a single Euler angle matrix. Relative motion between the joint can be calculated from the output of 2 of the measuring units. The sensors are calibrated with an average static orientation error of +/−0.7 degree and standard deviation of 1.8 degrees. The dynamic orientation error of rotating around a single axis is 2.38, 0.15 and 0.517 degrees with standard deviation of 0.99, 0.98 and 0.7 degree for roll, pitch and yaw respectively. The initial design shows good result for human body motion tracking. The performance of the unit can be further improved with optimizing the filter and using the data from different type of the sensors to compensate each other

Aims. Few reports compare the contribution of the talonavicular articulation to overall range of movement in the sagittal plane after total ankle arthroplasty (TAA) and tibiotalar arthrodesis. The purpose of this study was to assess changes in ROM and functional outcomes following tibiotalar arthrodesis and TAA. Patients and Methods. Patients who underwent isolated tibiotalar arthrodesis or TAA with greater than two-year follow-up were enrolled in the study. Overall arc of movement and talonavicular movement in the sagittal plane were assessed with weight-bearing lateral maximum dorsiflexion and plantarflexion radiographs. All patients completed Short Form-12 version 2.0 questionnaires, visual analogue scale for pain (VAS) scores, and the Foot and Ankle Ability Measure (FAAM). Results. In all, 41 patients who underwent TAA and 27 patients who underwent tibiotalar arthrodesis were enrolled in the study. The mean total arc of movement was 34.2° (17.0° to 59.1°) with an average contribution from the talonavicular joint of 10.5° (1.2° to 28.8°) in the TAA cohort. The average total arc of movement was 24.3° (6.9° to 44.3°) with a mean contribution from the talonavicular joint of 22.8° (5.6° to 41.4°) in the arthrodesis cohort. A statistically significant difference was detected for both total sagittal plane movement (p = 0.00025), and for talonavicular motion (p < 0.0001). A statistically significant lower VAS score (p = 0.0096) and higher FAAM (p = 0.01, p = 0.019, respectively) was also detected in the TAA group. Conclusion. TAA preserves more anatomical movement, has better pain relief and better patient-perceived post-operative function compared with patients undergoing fusion. The relative increase of talonavicular movement in fusion patients may play a role in the outcomes compared with TAA and may predispose these patients to degenerative changes over time. Take home message: TAA preserves more anatomic sagittal plane motion and provides greater pain relief and better patient-perceived outcomes compared with ankle arthrodesis. Cite this article: Bone Joint J 2016;98-B:634–40

Study Purpose. A preliminary study to compare continuous sagittal plane lumbar inter-vertebral kinematics in 10 healthy volunteers in recumbent and weight bearing configurations using quantitative fluoroscopy. Background. There are no direct in-vivo comparisons between continuous weight bearing and non-weight bearing inter-vertebral kinematics in the same healthy individuals. This information will advance our knowledge of spine mechanics and provide reference values for clinical studies. Methods. Ten male healthy control volunteer subjects aged between 30 and 50 underwent a recumbent bending procedure during fluoroscopy. All participants repeated this in weight bearing. Trunk motion was controlled for range and velocity. Digital image sequences (DICOM) of these movements were captured at 15 fps and analysed using automated frame to frame image registration codes in MATLAB (Mathworks). Inter-vertebral motion characteristics, including inter-vertebral angular range of rotation and attainment rate (Laxity), were calculated. Results. These results are the preliminary output of an ongoing study to create a reference database for normal spine kinematics. Comparisons of the motion patterns within and between participants will be demonstrated along with preliminary statistical analysis of range of motion and speed of attainment (laxity) of the angular range within the first 10° of trunk motion after the inter-vertebral motion starts. Laxity is proposed as a new in vivo proxy for the neutral zone where force is replaced by trunk motion near the neutral position. Conclusion. These preliminary comparisons demonstrate the feasibility of establishing a reference database of lumbar spine kinematics to which patient populations can be compared, potentially allowing these to emerge as outcome measures. No conflicts of interest. Sources of funding: PhD studentship: School of Design Engineering and Computing, Bournemouth University. This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

As the field of hip arthroscopy continues to develop, functional measures and testing become increasingly important in patient selection, managing patient expectations prior to surgery, and physical readiness for return to athletic participation. The Hip Sport Test (HST) was developed to assess strength, coordination, agility, and range of motion prior to and following hip arthroscopy as a functional assessment. However, the relationship between HST and hip strength, range of motion, and hip-specific patient reported outcome (PRO) measures have not been investigated. The purpose of this study was to evaluate the correlation between the HST scores and measurements of hip strength and range of motion prior to undergoing hip arthroscopy. Between September 2009 and January 2017, patients aged 18-40 who underwent primary hip arthroscopy for the treatment of femoroacetabular impingement with available pre-operative HST, dynamometry, range of motion, and functional scores (mHHS, WOMAC, HOS-SSS) were identified. Patients were excluded if they were 40 years old, had a Tegner activity score < 7, or did not have HST and dynamometry evaluations within one week of each other. Muscle strength scores were compared between affected and unaffected side to establish a percent difference with a positive score indicating a weaker affected limb and a negative score indicating a stronger affected limb. Correlations were made between HST and strength testing, range of motion, and PROs. A total of 350 patients met inclusion criteria. The average age was 26.9 ± 6.5 years, with 34% females and 36% professional athletes. Total and component HST scores were significantly associated with measure of strength most strongly for flexion (rs = −0.20, p < 0 .001), extension (rs = −0.24, p<.001) and external rotation (rs = −0.20, p < 0 .001). Lateral and diagonal agility, components of HST, were also significantly associated with muscle strength imbalances between internal rotation versus external rotation (rs = −0.18, p=0.01) and flexion versus extension (rs = 0.12, p=0.03). In terms of range of motion, a significant correlation was detected between HST and internal rotation (rs = −0.19, p < 0 .001). Both the total and component HST scores were positively correlated with pre-operative mHHS, WOMAC, and HOS-SSS (p<.001 for all rs). The Hip Sport Test correlates with strength, range of motion, and PROs in the preoperative setting of hip arthroscopy. This test alone and in combination with other diagnostic examinations can provide valuable information about initial hip function and patient prognosis

Aims. The objective of this study was to compare simulated range of motion (ROM) for reverse total shoulder arthroplasty (rTSA) with and without adjustment for scapulothoracic orientation in a global reference system. We hypothesized that values for simulated ROM in preoperative planning software with and without adjustment for scapulothoracic orientation would be significantly different. Methods. A statistical shape model of the entire humerus and scapula was fitted into ten shoulder CT scans randomly selected from 162 patients who underwent rTSA. Six shoulder surgeons independently planned a rTSA in each model using prototype development software with the ability to adjust for scapulothoracic orientation, the starting position of the humerus, as well as kinematic planes in a global reference system simulating previously described posture types A, B, and C. ROM with and without posture adjustment was calculated and compared in all movement planes. Results. All movement planes showed significant differences when comparing protocols with and without adjustment for posture. The largest mean difference was seen in external rotation, being 62° (SD 16°) without adjustment compared to 25° (SD 9°) with posture adjustment (p < 0.001), with the highest mean difference being 49° (SD 15°) in type C. Mean extension was 57° (SD 18°) without adjustment versus 24° (SD 11°) with adjustment (p < 0.001) and the highest mean difference of 47° (SD 18°) in type C. Mean abducted internal rotation was 69° (SD 11°) without adjustment versus 31° (SD 6°) with posture adjustment (p < 0.001), showing the highest mean difference of 51° (SD 11°) in type C. Conclusion. The present study demonstrates that accounting for scapulothoracic orientation has a significant impact on simulated ROM for rTSA in all motion planes, specifically rendering vastly lower values for external rotation, extension, and high internal rotation. The substantial differences observed in this study warrant a critical re-evaluation of all previously published studies that examined component choice and placement for optimized ROM in rTSA using conventional preoperative planning software. Cite this article: Bone Joint J 2024;106-B(11):1284–1292

Introduction. Sheffield Children's Hospital specialises in limb lengthening for children. Soft tissue contracture and loss of range of motion at the knee and ankle are common complications. This review aims to look at therapeutic techniques used by the therapy team to manage these issues. Materials & Methods. A retrospective case review of therapy notes was performed of femoral and tibial lengthening's over the last 3 years. Included were children having long bone lengthening with an iIntramedullary nail, circular frame or mono-lateral rail. Patients excluded were any external fixators crossing the knee/ankle joints. Results. 20 tibial and 25 femoral lengthening's met the inclusion criteria. Pathologies included, complex fractures, limb deficiency, post septic necrosis and other congenital conditions leading to growth disturbance. All patients had issues with loss of motion at some point during the lengthening process. The knee and foot/ankle were equally affected. Numerous risk factors were identified across the cohort. Treatment provided included splinting, serial casting, bolt on shoes, exercise therapy, electrical muscle stimulation and passive stretching. Conclusions. Loss of motion in lower limb joints was common. Patients at higher risk were those with abnormal anatomy, larger target lengthening's, poor compliance or lack of access to local services. Therapy played a significant role in managing joint motion during treatment. However, limitations were noted. No one treatment option gave preferential outcomes, selection of treatment needed to be patient specific. Future research should look at guidelines to aid timely input and avoid secondary complications

Study purpose and background. Kinematic variables have been identified as potential biomarkers for low back pain patients; however, an in-depth comparison between chronic (n=22), acute (n=15), and healthy controls (n=136) has not been done. This retrospective data analysis compared intervertebral lumbar motion parameters, angular range of motion, translation, maximum disc height, motion share inequality (MSI) and variability (MSV), and laxity, between these groups. Methods and results. Kinematic parameters were determined using video tracking techniques utilising quantitative fluoroscopy (QF), during both weight-bearing and recumbent controlled sagittal bending tasks. Data was analysed for normality, and appropriate statistical tests were applied to determine differences between groups. There were no significant differences between the groups for age, height, weight and sex. Whilst few differences were found between acute and healthy groups, differences were shown between both chronic and healthy, and acute and chronic groups for all six parameters. Of particular note were examples of differences in the motion share parameters between the acute and chronic populations, with an increased MSI in the chronic group during recumbent flexion, and MSV during recumbent extension, and inversely an increase in MSV in the acute group during weight-bearing flexion. Conclusion. Analysis of intervertebral lumbar motion provides valuable insights into kinematic differences between chronic, acute, and healthy control populations. These findings suggest that there is variation between the groups which is knowledge that may benefit management strategies. Further exploration of the time varying data is warranted to explore how such differences may relate to the motion share inequalities and variability shown. Conflicts of Interest. No conflicts of interest. Sources of Funding. No funding obtained

Aims. In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement. Methods. Total hip arthroplasty (THA) motion while standing and sitting was simulated using a MATLAB model (one stem with a cylindrical neck and one stem with a rectangular neck). The primary predictor was the geometry of the neck (cylindrical vs rectangular) and the main outcome was the shape of ROM based on the prosthetic impingement between the neck and the liner. The secondary outcome was the difference in the ROM provided by each neck geometry and the effect of the pelvic tilt on this ROM. Multiple regression was used to analyze the data. Results. The stem with a rectangular neck has increased internal and external rotation with a quatrefoil cross-section compared to a cone in a cylindrical neck. Modification of the cup orientation and pelvic tilt affected the direction of projection of the cone or quatrefoil shape. The mean increase in internal rotation with a rectangular neck was 3.4° (0° to 7.9°; p < 0.001); for external rotation, it was 2.8° (0.5° to 7.8°; p < 0.001). Conclusion. Our study shows the importance of attention to femoral implant design for the assessment of prosthetic impingement. Any universal mathematical model or computer simulation that ignores each stem’s unique neck geometry will provide inaccurate predictions of prosthetic impingement. Cite this article: Bone Joint Res 2021;10(12):780–789

To determine the biomechanical effect of increasing scaphoid malunion and scaphoid non-union on carpal kinematics during dynamic wrist motion using an active wrist motion simulator. Seven cadaveric upper extremities underwent active wrist flexion and extension in a custom motion wrist simulator with scaphoid kinematics being captured with respect to the distal radius. A three-stage protocol of progressive simulated malunion severity was performed (intact, 10° malunion, 20° malunion) with data analyzed from 45° wrist flexion to 45° wrist extension. Scaphoid malunions were modelled by creating successive volar wedge osteotomies and fixating the resultant scaphoid fragments with 0.062 Kirshner wires. At the completion of malunion motion trials, a scaphoid non-union trial was carried out by removing surgical fixation to observe motion differences from the malunion trials. Motion of the scaphoid, lunate, capitate, and trapezium-trapezoid was recorded and analyzed using active optical trackers. Increasing scaphoid malunion severity did not significantly affect scaphoid or trapezium-trapezoid motion (p>0.05); however, it did significantly alter lunate motion (p<0.001). Increasing malunion severity resulted in progressive lunate extension across wrist motion (Intact – Mal 10: mean dif. = 7.1° ± 1.6, p<0.05; Intact – Mal 20: mean dif. = 10.2° ± 2.0, p<0.05;) although this change was not as great as the difference seen during non-union trials (native – non-union: mean dif. = 13.8° ± 3.7, p<0.05). In this in-vitro model, increasing scaphoid malunion severity was associated with progressive extension of the lunate in all wrist positions. The clinical significance of this motion change is yet to be elucidated, but this model serves as a basis for understanding the kinematic consequences of scaphoid malunion deformities

Range of Motion (ROM) assessments are routinely used during joint replacement to evaluate joint stability before, during and after surgery to ensure the effective restoration of patient biomechanics. This study aimed to quantify axial torque in the femur during ROM assessment in total hip arthroplasty to define performance criteria against which hip instruments can be verified. Longer term, this information may provide the ability to quantitatively assess joint stability, extending to quantitation of bone preparation and quality. Joint loads measured with strain-gaged instruments in five cadaveric femurs prepared using posterior approach were analysed. Variables such as surgeon-evaluator, trial offset and specimen leg and weight were used to define 13 individual setups and paired with surgeon appraisal of joint tension for each setup. Peak torque loads were then identified for specific motions within the ROM assessment. The largest torque measured in most setups was observed during maximum extension and external rotation of the joint, with a peak torque of 13Nm recorded in a specimen weighing 98kg. The largest torque range (19.4Nm) was also recorded in this specimen. Other motions within the trial reduction showed clear peaks in applied torque but with lower magnitude. Relationships between peak torque, torque range and specimen weight produced an R2 value greater than 0.65. The data indicated that key influencers of torsional loads during ROM were patient weight, joint tension and limb motion. This correlation with patient weight should be further investigated and highlights the need for population representation during cadaveric evaluation. Although this study considered a small sample size, consistent patterns were seen across several users and specimens. Follow-up studies should aim to increase the number of surgeon-evaluators and further vary specimen size and weight. Consideration should also be given to alternative surgical approaches such as the Direct Anterior Approach

Aims. We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry. Methods. In this prospective observational study, we analyzed 35 primary TKAs (24 patients) for knee osteoarthritis. We measured the knee angles in flexion and extension using OpenPose, radiography, and goniometry. We assessed the test-retest reliability of each method using intraclass correlation coefficient (1,1). We evaluated the ability to estimate other measurement values from the OpenPose value using linear regression analysis. We used intraclass correlation coefficients (2,1) and Bland–Altman analyses to evaluate the agreement and error between radiography and the other measurements. Results. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1,1) = 1.000). The R. 2. of all regression models indicated large correlations (0.747 to 0.927). In the flexion position, the intraclass correlation coefficients (2,1) of OpenPose indicated excellent agreement (0.953) with radiography. In the extension position, the intraclass correlation coefficients (2,1) indicated good agreement of OpenPose and radiography (0.815) and moderate agreement of goniometry with radiography (0.593). OpenPose had no systematic error in the flexion position, and a 2.3° fixed error in the extension position, compared to radiography. Conclusion. OpenPose is a reliable and valid tool for measuring flexion and extension positions after TKA. It has better accuracy than goniometry, especially in the extension position. Accurate measurement values can be obtained with low error, high reproducibility, and no contact, independent of the examiner’s skills. Cite this article: Bone Joint Res 2023;12(5):313–320

For clinical movement analysis, optical marker-based motion capture is the gold standard. With the advancement of AI-driven computer vision, markerless motion capture (MMC) has emerged. Validity against the marker-based standard has only been examined for lightly-dressed subjects as required for marker placement. This pilot study investigates how different clothing affects the measurement of typical gait metrics. Gait tests at self-selected speed (4 km/h) were performed on a treadmill (Motek Grail), captured by 9 cameras (Qualisys Miqus, 720p, f=100Hz) and analyzed by a leading MMC application (Theia, Canada). A healthy subject (female, h=164cm, m=54kg) donned clothes between trials starting from lightly dressed (LD: bicycle tight, short-sleeved shirt), adding a short skirt (SS: hip occlusion) or a midi-skirt (MS: partial knee occlusion) or street wear (SW: jeans covering ankle, long-sleeved blouse), the lattern combined with a short jacket (SWJ) or a long coat (SWC). Gait parameters (mean±SD, t=10s) calculated (left leg, mid-stance) were ankle pronation (AP-M), knee flexion (KF-M), pelvic obliquity (PO-M) and trunk lateral lean (TL-M) representing clinically common metrics, different joints and anatomic planes. Four repetitions of the base style (LD) were compared to states of increased garment coverage using the t-test (Bonferroni correction). For most gait metrics, differences between the light dress (LD) and various clothing styles were absent (p>0.0175), small (< 2SD) or below the minimal clinically important differences (MCID). For instance, KF-M was for LD=10.5°±1.7 versus MD=12.0°±0.5 (p=0.07) despite partial knee cover. AP-M measured for LD=5.2°±0.6 versus SW=4.1°±0.7 (p<0.01) despite ankle cover-up. The difference for KF-M between LD=10.5°±1.7 versus SWL=6.0°±0.9, SW and SWJ (7.6°±1.5, p<0.01) indicates more intra-subject gait variability than clothing effect. This study suggests that typical clothings styles only have a small clinically possibly negligible effect on common gait parameters measured with MMC. Thus, patients may not need to change clothes or be instructed to wear specific garments. In addition to avoiding marker placement, this further increases speed, ease and economy of clinical gait analysis with MMC facilitating high volume or routine application