Introduction: Unicompartmental knee arthroplasty (UKA) is a proven for treatment of knee osteoarthritis (OA). Survival rates have been found comparable with total knee arthroplasty (TKA) in specialty hospitals series, but registry based studies show worse results of survival of UKA. High BMI, age of the patient, patellofemoral arthritis or learning curve have been found to have only mild consequences to the survival rates. Original indications for Oxford UKA in OA are severe pain and full thickness cartilage loss with bone-on-bone contact in the medial side. After widespread use of UKA surgeons are broadening their indications. Purpose of this study was to evaluate the influence of preoperative degree of OA on survival rate of UKA. Material and Methods: 113 knees in 103 patients were operated with Oxford phase 3 UKA. We evaluated all the patient data retrospectively and patient age, body mass index (BMI), sex, earlier arthroscopies, operation time, follow-up time, preoperative medial joint space widths, reoperations and survival of UKA was recorded. Results: The mean age of the patients was 58 years (38–81) and mean follow-up time was 47 months (3–114). 22 UKAs were revised and the overall survival rate was 80.5%. 68% of revised knees have had undergone arthroscopy before UKA to confirm existence of arthritis. Odds ratio for female gender was statistically non-significant 1.59 (95% CI 0.57–4.45, p=0.46,). For BMI and patient’s age, the association remained non-significant with odds ratios of 1.07 (95% CI 0.98–1.17, p=0.14) and 0.96 (95% CI 0.90–1.02, p=0.19). Patients were divided four sub-groups according medial joint space width (medial joint space width ≤2 mm and > 2 mm) and Lateral/medial joint space width ratio (L/M-ratio ≤2.5 and > 2.5). Over 2 mm medial joint space width or L/M-ratio less than 2.5 were found significant risk factors for revisions, odds ratios being 6.00 (95% CI 2.12–17.00, p< 0.01) and 7.88 (95% CI 2.76–22.54, p< 0.01), respectively. Discussion: Nowadays UKAs are performed on patients with mild OA against the original indications. In more severe OA varus alignment of the knee causes mechanical overload to the medial compartment, which is well corrected by UKA. Also it is possible that in the cases of prolonged knee pain caution is focused incorrectly to mild OA, which is typical radiological finding even in asymptomatic middle aged and elderly patients. Also in the early phase of OA it is impossible to estimate progression of cartilage damage in other two compartments. In conclusion we suggest that not to extend original indication of UKA and patient should have true medial bone-on-bone OA in preoperative radiographs. Performing UKA for patients with medial joint space width over 2 mm or L/M-ratio less than 2.5 should be concerned particularly careful

Introduction. Three-dimensional (3D) morphological understanding of the hip joint, specifically the joint space and surrounding anatomy, including the proximal femur and the pelvis bone, is crucial for a range of orthopedic diagnoses and surgical planning. While deep learning algorithms can provide higher accuracy for segmenting bony structures, delineating hip joint space formed by cartilage layers is often left for subjective manual evaluation. This study compared the performance of two state-of-the-art 3D deep learning architectures (3D UNET and 3D UNETR) for automated segmentation of proximal femur bone, pelvis bone, and hip joint space with single and multi-class label segmentation strategies. Method. A dataset of 56 3D CT images covering the hip joint was used for the study. Two bones and hip joint space were manually segmented for training and evaluation. Deep learning models were trained and evaluated for a single-class approach for each label (proximal femur, pelvis, and the joint space) separately, and for a multi-class approach to segment all three labels simultaneously. A consistent training configuration of hyperparameters was used across all models by implementing the AdamW optimizer and Dice Loss as the primary loss function. Dice score, Root Mean Squared Error, and Mean Absolute Error were utilized as evaluation metrics. Results. Both the models performed at excellent levels for single-label segmentations in bones (dice > 0.95), but single-label joint space performance remained considerably lower (dice < 0.87). Multi-class segmentations remained at lower performance (dice < 0.88) for both models. Combining bone and joint space labels may have introduced a class imbalance problem in multi-class models, leading to lower performance. Conclusion. It is not clear if 3D UNETR provides better performance as the selection of hyperparameters was the same across the models and was not optimized. Further evaluations will be needed with baseline UNET and nnUNET modeling architectures

Scaphoid fractures are a common injury accounting for more than 58% of all carpal bone fractures(1,2). Biomechanical studies have suggested that scaphoid mal-union may lead to altered carpal contact mechanics causing decreased motion, pain and arthritis(1,2). The severity of mal-union required to cause deleterious effects has yet to be established. This limits the ability to define surgical indications or impacts on prevention of posttraumatic arthritis. Computed tomography has been shown to be a useful in determining the 3D implications of altered bony alignment on the joint contact mechanics of surrounding joints. The objective of this study was to report mid-term follow-up image-based outcomes of patients with scaphoid mal-unions to determine the extent to which arthritic changes and decreased joint space is present after a minimum of 4 years following fracture. Participants (n=14) who had previously presented with a mal-united scaphoid fracture (indicated by a Height:Length Ratio >0.6) between November 2005 and November 2013 were identified and contacted. A short-arm thumb spica case was used to treat X patients and X required surgical management. Baseline and follow-up CT images, were performed with the wrist in radial deviation and positioned such that the long axis of the scaphoid was perpendicular to the axis of the scanner. Three-dimensional inter-bone distance (joint space), a measure of joint congruency and 3D alignment, was quantified from reconstructed CT bone models of the distal radius, scaphoid, lunate, capitate, trapezium and trapezoid from both the baseline and follow-up scans(3). Repeated measures ANOVA was used to detect differences in contact area (mm2) between baseline and follow-up CT's for the radioscaphoid, scaphocapitate and scaphotrapezium-trapezoid joint. The average age of participants was 43.1 years (16–64 years old). There was significant loss of joint space, indicated by a greater joint contact area 3–4 years post fracture, between baseline and follow-up reconstruction models, at the scaphocapitate (mean difference: 21.5±146mm2, p=0.007) and scaphotrapezoid joints (mean difference: 18.4 ±28.6mm2, 0.042). Significant differences in the measured contact area was not found for the radioscaphoid (0.153) and scaphotrapezium joints (0.72). Additionally, the scaphoid, qualitatively, appears to track in the vorsal direction in the majority of patients following fracture. Increased joint contact area in the scaphocapitate and scaphotrapezoid joint 3–4 years following fracture results from decreased 3D joint space and overall narrowing. Joint space narrowing, while not significantly different for all joints examined, was reduced for all joints surrounding the scaphoid. Decreased joint space and increased contact area detectable within this short interval might be suggestive of a trajectory for developing arthritis in the longer term, and illustrates the potential value of these measures for early detection. Longer term follow-up and correlation to clinical outcomes are needed to determine the importance of early joint space narrowing, and to identify those most at risk

Introduction. Although surgical remedies tend to be the long-term solutions for patients with osteoarthritis (OA), many alternatives exist that offer the potential to slow progression, alleviate pain, and/or restore function. One such option is the unloader OA knee brace. The objective of this study was to assess the in vivo medial joint space narrowing with and without the brace during weight-bearing portion of gait. Methods. Twenty subjects were evaluated after being clinically assessed by a single surgeon to be bone-on-bone on the medial side. In vivo gait kinematics were collected using a validated 3D-to-2D fluoroscopic registration technique (Figure 1). Subjects were asked to first walk on a treadmill without a brace (Figure 2), and then, after a qualified technician fit a properly sized brace to each subject, they were asked to walk again (Figure 3). In vivo fluoroscopic images were captured and registered at heel-strike (HS) and mid stance (MS) for both scenarios. CT scans were used to acquire the patient-specific bone models that were used in the registration process. Results. All twenty subjects experienced a positive increase in medial joint space and verbally stated their knee pain lessened while wearing the brace. The average medial joint space change was 1.7±0.8 mm (3.1 max, 0.3 min) at HS and 1.6±0.8 mm (3.7 max, 0.4 min) at MS (Figure 4). Five patients experienced more than 2.5 mm of medial joint space change when wearing the unloader brace, indicating substantial effectiveness of the brace. Conclusion. While previous unloader brace studies have focused on outcome scores and patient satisfaction to analyze brace effectiveness, this study quantifiably demonstrated improvement in joint space narrowing due to the unloader brace. These results suggest that unloader braces may provide benefit in the interim when symptoms of OA are present prior to need for surgical intervention. For any figures or tables, please contact the authors directly

INTRODUCTION. Controversy exists regarding the ability of unicompartmental knee arthroplasty (UKA) to restore native knee kinematics, with some studies suggesting native kinematics are restored in most or all patients after UKA. 1–3. , while others indicate UKA fails to restore native knee kinematics. 4,5. Previous analysis of UKA articular contact kinematics focused on the replaced compartment. 2,5. , neglecting to assess the effects of the arthroplasty on the contralateral compartment which may provide insight to future pathology such as accelerated degeneration due to overload. 6. or a change in the location of cartilage contact. 7. The purpose of this study was to assess the ability of medial UKA to restore native knee kinematics, contact patterns, and lateral compartment dynamic joint space. We hypothesized that medial UKA restores knee kinematics, compartmental contact patterns, and lateral compartment dynamic joint space. METHODS. Six patients who received fixed-bearing medial UKA consented to participate in this IRB-approved study. All patients (4 M, 2 F; average age 62 ± 6 years) completed pre-surgical (3 weeks before) and post-surgical (7±2 months) testing. Synchronized biplane radiographs were collected at 100 images per second during three repetitions of a chair rise movement (Figure 1). Motion of the femur, tibia, and implants were tracked using an automated volumetric model-based tracking process that matches subject-specific 3D models of the bones and prostheses to the biplane radiographs with sub-millimeter accuracy. 8. Anatomic coordinate systems were created within the femur and tibia. 9. and used to calculate tibiofemoral kinematics. 10. Additional outcome measures included the center of contact in the medial and lateral compartments, and the lateral compartment dynamic joint space (i.e. the distance between subchondral bone surfaces). 11. The results of the three movement trials were averaged for each knee in each test session. All outcome measures were interpolated at 5° increments of knee extension (Figure 2). The average differences between knees at corresponding flexion angles were analyzed using paired t-tests with significance set at p < 0.05. RESULTS. The UKA knee was in 5.3° more varus than the contralateral knee prior to surgery (p=0.005). After surgery, the UKA knee was in 4.9° more valgus than before surgery (p=0.005). The UKA knee was 4.3° more externally rotated than the contralateral knee post-surgery (p=0.05) (Table 1). No significant differences were observed between knees or pre- to post-surgery in lateral compartment dynamic joint space or the center of contact in the medial and lateral tibia compartments (Table 1). DISCUSSION. These results suggest that medial UKA can restore native knee varus without significantly altering lateral compartment joint space or contact location during the chair rise movement. For any figures or tables, please contact the authors directly

In a longitudinal case-control study, we followed 81 subjects with dysplasia of the hip and 136 control subjects without dysplasia for ten years assessing radiological evidence of degeneration of the hip at admission and follow-up. There were no cases of subluxation in the group with dysplasia. Neither subjects with dysplasia nor controls had radiological signs of ongoing degenerative disease at admission. The primary radiological discriminator of degeneration of the hip was a change in the minimum joint space width over time. There were no significant differences between these with dysplasia and controls in regard to age, body mass index or occupational exposure to daily repeated lifting at admission. We found no significant differences in the reduction of the joint space width at follow-up between subjects with dysplasia and the control subjects nor in self-reported pain in the hip. The association of subluxation and/or associated acetabular labral tears with dysplasia of the hip may be a conditional factor for the development of premature osteoarthritis in mildly to moderately dysplastic hips

Aims. To explore the clinical relevance of joint space width (JSW) narrowing on standardized-flexion (SF) radiographs in the assessment of cartilage degeneration in specific subregions seen on MRI sequences in knee osteoarthritis (OA) with neutral, valgus, and varus alignments, and potential planning of partial knee arthroplasty. Methods. We retrospectively reviewed 639 subjects, aged 45 to 79 years, in the Osteoarthritis Initiative (OAI) study, who had symptomatic knees with Kellgren and Lawrence grade 2 to 4. Knees were categorized as neutral, valgus, and varus knees by measuring hip-knee-angles on hip-knee-ankle radiographs. Femorotibial JSW was measured on posteroanterior SF radiographs using a special software. The femorotibial compartment was divided into 16 subregions, and MR-tomographic measurements of cartilage volume, thickness, and subchondral bone area were documented. Linear regression with adjustment for age, sex, body mass index, and Kellgren and Lawrence grade was used. Results. We studied 345 neutral, 87 valgus, and 207 varus knees. Radiological JSW narrowing was significantly (p < 0.01) associated with cartilage volume and thickness in medial femorotibial compartment in neutral (r = 0.78, odds ratio (OR) 2.33) and varus knees (r = 0.86, OR 1.92), and in lateral tibial subregions in valgus knees (r = 0.87, OR 3.71). A significant negative correlation was found between JSW narrowing and area of subchondral bone in external lateral tibial subregion in valgus knees (r = −0.65, p < 0.01) and in external medial tibial subregion in varus knees (r = −0.77, p < 0.01). No statistically significant correlation was found in anterior and posterior subregions. Conclusion. SF radiographs can be potentially used for initial detection of cartilage degeneration as assessed by MRI in medial and lateral but not in anterior or posterior subregions. Cite this article: Bone Joint Res 2021;10(3):173–187

Purpose: Radial head replacement with a prosthesis that is too thick has been reported to be associated with stiffness, pain and capitellar wear. Radiographic widening of the lateral ulnohumeral joint following radial head replacement has been used as a criterion to diagnose overstuffing of the radiocapitellar joint. The purpose of this study was to show that widening of the lateral ulnohumeral joint is a normal anatomic variant and therefore cannot be used conclusively to diagnose radiocapitellar joint overstuffing. Methods: Fifty normal standardized anteroposterior elbow radiographs from 50 patients with a mean age of 48 years were reviewed to evaluate variations in the joint space between the medial and lateral facets of the ulnohumeral joint. Using computer software at 4x magnification (GE, Fairfield, CT), two lines were drawn perpendicular to the lateral ulnohumeral joint and two lines perpendicular to the medial ulnohumeral joint. The difference in length of these two lines was used to assess how parallel the lateral and medial joint spaces are. The lengths of the two lines were averaged to compare lateral joint space thickness to medial joint space thickness. Results: The width of the lateral ulnohumeral joint space (3.6mm & #61617; 0.8mm) was greater than the medial ulnohumeral joint space (2.8mm & #61617; 0.5mm) (p< 0.001). The lengths of the two medial joint space perpendicular lines were similar (p> 0.05), indicating the medial joint space is normally parallel. The lengths of the lateral joint space perpendicular lines were greater laterally (p= 0.02), indicating the lateral joint is not normally parallel. Conclusions: The lateral ulnohumeral joint space is often wider than the medial ulnohumeral joint space on an anteroposteror radiograph of the normal elbow. While the medial ulnohumeral joint space is usually parallel, the lateral ulnohumeral joint space may be non-parallel and wider laterally, therefore, lateral joint space widening is not a reliable indicator of radiocapitellar joint overstuffing. A non-parallel medial ulnohumeral joint space may be suggestive of possible overstuffing of a radial head arthroplasty, however, comparison radiographs of the uninjured elbow is likely the best investigation to consider when overstuffing is suspected

Purpose: The aetiology of primary omarthrosis is still unclear. Typical radiological changes are joint space narrowing and the development of caudal osteophytes. The objective of the study is the analysis of the joint space of the shoulder in four different age groups. Materials and Methods: Retrospective analysis of n=342 standardized X-rays (2002–2009) (true ap, axillary). Inclusion criteria: normal adulthood group I (n=60), instability group II (n=53), calcifying tendonitis of the supraspinatus tendon group III (n=109), advanced primary omarthrosis group IV (n=120). Measurement of joint space at three levels (ap: superior, central, inferior; axillary: anterior, central, posterior). Two independent measurements. Statistical analysis SPSS 17.0: U-Test acc. Mann and Whitney. Bivariate correlation analysis (Spearman), partial correlation analysis, intraclass correlation coefficient. Results: Mean age group I 17.84±1.54, group II 31.6±11.8, group III 48.2±8.0, group IV 66.43 ±9.74 (p=0.001). Measurement joint space: interobserver reliability excellent in the ap-projection (r=0.887–0.910) and in the axillary projection (r=0.879–0.886). Joint space group I: 4.79mm±0.84 superior ap, 4.28mm±0.75 central ap, 4.57mm±0.80 inferior ap, 6.59mm±1.44 anterior axillary, 6.12mm±1.09 central axillary and 7.03mm±1.17 posterior axillary; group II: 3.78mm±0.99 superior ap, 3.12mm±0.73 central ap, 3.38mm±0.80 inferior ap, 3.92mm±1.08 anterior axillary, 3.92mm±0.77 central axillary and 4.79mm±1.18 posterior axillary; group III: 3.43mm±1.06 superior ap, 2.87mm±0.80 central ap, 3.25mm±0.79 inferior ap, 3.95mm±0.83 anterior axillary, 3.34mm±0.84 central axillary and 4.05mm±0.84 posterior axillary; group IV: 2.00mm±1.40 superior ap, 1.47mm±1.07 central ap, 1.48mm±1.93 inferior ap, 3.01mm±2.22 anterior axillary, 1.08mm±1.12 central axillary and 1.17mm±1.04 posterior axillary. The differences between the four groups for the joint space width are all statistically significant with p< 0.001 (except the difference between group I and group II for ap-central, ap-inferior and axillary anterior). There is a significant negative correlation (r= −0,579–0,813) between the joint space width and patients age at all measured levels in both projections (p< 0.001). This negative correlation is only little smaller (r= −0,430–0,655) but still clearly significant for all measurements, if the patients with present osteoarthritis (group III) are excluded. Conclusion: The data of the study show a decrease of joint space width in group I–IV in all measurements. This effect is negatively correlated with age. The data suggest that the decrease in joint space with loss of cartilage cover is an age-dependant process which is independent from the presence of osteoarthritis. This is in contrast to historical findings but in concordance with recent basic studies about cartilage ageing

Femoral lengthening has been associated with narrowing of the joint space at the hip. We have studied the joint space before lengthening in 20 patients with a short femur due to a femoral-shaft fracture (15) or distal femoral epiphyseal injury (5). Their mean age at injury was 16 years (3 to 27) and the mean shortening was 5.4 cm (1.1 to 14). We found that the hip joint space of the shortened femur was significantly narrower (p < 0.001) than that on the normal side, with a mean narrowing ratio of 15.5% (−5 to +43). The narrowing ratio was directly related to the period spent non-weight-bearing (p < 0.001), but not to the amount of femoral shortening. We have shown that the joint space of the hip in patients with post-traumatic femoral shortening was narrowed even before femoral lengthening had been started

Introduction: Evaluation of the hip joint space was performed in patients with Legg-Calve-Perthes disease in this study. Materials and Methods: Seventy-eight patients (85 affected hips and 71 unaffected hips) with LCP disease were reviewed respectively to evaluate widening of the hip joint space, the extent of epiphyseal subchondral fracture, and metaphyseal changes. The mean age of the patients was 7.4 years (range, 3–13 years). There were 27 hips at the initial stage, 23 at the fragmentation stage, and 11 at the healing stage. The metaphyseal changes in MRI scans were classified as no change, marrow edema, false cyst, and true cyst. The false cyst was defined as a cyst located at the epiphysis, physis, and metaphysis. The true cyst was defined as a cyst located within the metaphysis. Results:The widened medial joint space at the initial stage was filled with overgrown cartilage of the femoral head and acetabulum on Magnetic Resonance Imaging (MRI) and radiographs. At the fragmentation stage, there was both overgrown cartilage and markedly widened true medial joint space, which was filled with an amount of joint fluid and hypertrophied synovial tissue. Widening of the true medial joint space at the initial stage had no correlation with lateral subluxation, whereas there was a definite correlation at the fragmentation stage. In the healing stage, coxa magna contributed to lateral subluxation rather than the widening of the false medial joint space, because it had decreased or normalized because of ossification of this overgrown cartilage and normalization of the synovial hypertrophy. The overall proportion of agreement was conducted by two groups of observers according to different classification systems. The results for Catterall groups 2, 3, and 4 showed 70% agreement with the Salter-Thompson classification, 65% with the MRI classification, and 75% in the Catterall classification. The subchondral fracture line had a prognostic significance in 17 of 20 hips (85%). The MRI had a prognostic significance in 10 of 20 hips (50%). Among 85 hips, there were no changes in 32 hips, marrow edema in 13 hips, false cysts in 28 hips, and true cysts in 12 hips. Discussion: The hips without metaphyseal change had less involvement of the epiphysis compared to the hips with the metaphyseal change. Metaphyseal cysts disappeared on radiographs and MRI scans during the healing or remodeling stage

Introduction. Chronic uneven distribution of forces over the articular cartilage, which are present in OA, has been shown to be a risk factor for the development of OA. Certain regions of the articular cartilage will be exposed to increased chronic peak loads, whereas other regions encounter a corresponding relative reduction of transmitted forces. This has a well known influence on cartilage viability and is a precursor of degenerative progression. Congruence of joints has an important impact on force distribution across articular surfaces. Therefore, tibiofemoral incongruence could lead to alterations of load distribution and ultimately to progressive degenerative changes. In clinical practice the routine method for evaluation of progressive OA is analysis of joint space width (JSW) using weight bearing radiographs. Recent studies have suggested that JSW has a strong positive correlation with cartilage compression, volume and meniscal extrusion. Lateral unicondylar knee arthroplasty (UKA) has gained increasing popularity over the last decade in the treatment of isolated unicompartmental osteoarthritis (OA). However, progressive degenerative alterations of the medial compartment following lateral unicompartmental knee arthroplasty remains a leading cause of revision surgery. Therefore, the purpose of this study is to evaluate the medial compartment congruence (MCC) and joint space width (JSW) alterations following lateral UKA. Methods. The MCC of 53 knees following lateral UKA was evaluated on pre- and postoperative radiographs and compared to 41 healthy knees, using an Interative Closest Point (ICP) algorithm. The ICP algorithm calculated the Congruence Index (CI) by performing a rigid transformation that best aligns the digitized tibial and femoral surfaces (figure 1A). Inner, middle and outer JSW was measured by subdividing the medial compartment into four quarters on weight bearing tunnel view radiographs pre- and postoperatively (figure 1B). Results. The measured CI of the healthy control group was 0.99. The pre-operative CI of knees undergoing lateral UKA was 0.92, which significantly improved to 0.96 (p<0.0001) post-operatively (figure 2). Post-operatively the inner JSW increased (p=0.006) and the outer decreased (p=0.002). JSW was restored post-operatively since no significant differences were noted in all three measured post-operative JSW locations compared to the control group (figure 3). Conclusion. Our data suggests that lateral UKA improves MCC and normalizes JSW of the medial compartment, potentially preventing osteoarthritic progression in the uninvolved medial compartment

There have been many reports which suggest that in patients with tibiofemoral osteoarthritis, a reduction in joint space is demonstrated better on weight-bearing radiographs taken with the knee in semiflexion than in full extension. The reduction has been attributed to the loss of articular cartilage in the contact area in a semiflexed arthritic knee. None of these studies have, however, included normal knees. We have therefore undertaken a prospective, double-blind, randomised study in order to evaluate the difference in the joint-space of arthroscopically-proven normal tibiofemoral joints as seen on weight-bearing full-extension and 30° flexion posteroanterior radiographs. Twenty-two knees were evaluated and the results showed that there may be a difference of up to 2 mm in the two views. This difference could be attributed to the inherent differential thickness of the articular cartilage in different areas of the femoral and tibial condyles and a change in the areas of contact between them

Objectives. An important measure for the diagnosis and monitoring of knee osteoarthritis is the minimum joint space width (mJSW). This requires accurate alignment of the x-ray beam with the tibial plateau, which may not be accomplished in practice. We investigate the feasibility of a new mJSW measurement method from stereo radiographs using 3D statistical shape models (SSM) and evaluate its sensitivity to changes in the mJSW and its robustness to variations in patient positioning and bone geometry. Materials and Methods. A validation study was performed using five cadaver specimens. The actual mJSW was varied and images were acquired with variation in the cadaver positioning. For comparison purposes, the mJSW was also assessed from plain radiographs. To study the influence of SSM model accuracy, the 3D mJSW measurement was repeated with models from the actual bones, obtained from CT scans. Results. The SSM-based measurement method was more robust (consistent output for a wide range of input data/consistent output under varying measurement circumstances) than the conventional 2D method, showing that the 3D reconstruction indeed reduces the influence of patient positioning. However, the SSM-based method showed comparable sensitivity to changes in the mJSW with respect to the conventional method. The CT-based measurement was more accurate than the SSM-based measurement (smallest detectable differences 0.55 mm versus 0. 82 mm, respectively). Conclusion. The proposed measurement method is not a substitute for the conventional 2D measurement due to limitations in the SSM model accuracy. However, further improvement of the model accuracy and optimisation technique can be obtained. Combined with the promising options for applications using quantitative information on bone morphology, SSM based 3D reconstructions of natural knees are attractive for further development. Cite this article: E. A. van IJsseldijk, E. R. Valstar, B. C. Stoel, R. G. H. H. Nelissen, N. Baka, R. van’t Klooster, B. L. Kaptein. Three dimensional measurement of minimum joint space width in the knee from stereo radiographs using statistical shape models. Bone Joint Res 2016;320–327. DOI: 10.1302/2046-3758.58.2000626

Aims. The goal of closed reduction (CR) in the treatment of developmental dysplasia of the hip (DDH) is to achieve and maintain concentricity of the femoral head in the acetabulum. However, concentric reduction is not immediately attainable in all hips and it remains controversial to what degree a non-concentric reduction is acceptable. This prospective study is aimed at investigating the dynamic evolution of the hip joint space after CR in DDH using MRI. Methods. A consecutive series of patients with DDH who underwent CR since March 2014 were studied. Once the safety and stability were deemed adequate intraoperatively, reduction was accepted regardless of concentricity. Concentricity was defined when the superior joint space (SJS) and medial joint space (MJS) were both less than 2 mm, based on MRI. A total of 30 children, six boys and 24 girls, involving 35 hips, were recruited for the study. The mean age at CR was 13.7 months (3.5 to 27.6) and the mean follow-up was 49.5 months (approximately four years) (37 to 60). The joint space was evaluated along with the interval between the inverted and everted limbus. Results. Only three hips (8.6%) were fully concentric immediately after CR. During follow-up, 24 hips (68.6%) and 27 hips (77.1%) became concentric at six months and one year, respectively. Immediate SJS after CR decreased from 3.51 mm to 0.79 mm at six months follow-up (p = 0.001). SJS in the inverted group decreased from 3.75 mm to 0.97 mm at six months follow-up. SJS or MJS in the everted group were less than those in the inverted group at each time of follow-up (p = 0.008, p = 0.002). Conclusion. A stable, safe but non-concentric reduction achieved before the age of two years appears to improve over time with nearly 80% of hips becoming fully concentric by one year. Cite this article: Bone Joint J 2020;102-B(5):618–626

Background/Objective: Since estrogen receptors (ERα/ERβ) were identified in human chondrocytes, animal-and experimental studies have demonstrated the importance of continued estrogen production for the integrity of articular cartilage. However, human epidemiological support of the hypothesis has been inconclusive. The present study investigated the relationship between reduced bone mineral densities (BMD), as a surrogate parameter of endogenous estrogen status – assessed by digital x-ray radiogrammetry (DXR), and reduced minimum hip joint space width (JSW). Methods: Standardised hand radiographs of the Copenhagen Osteoarthritis Study cohort of 3.913 adults (1.470M/2.443F) with a mean age of 60 years (range, 18–92), were analysed by the X-Posure. ™. digital software v. 2.0 (Sectra-Pronosco). The system is operator independent. From 1.200 individual measurements per radiograph mean BMD was calculated. Minimum hip joint JSW was assessed in standardized, pelvic radiographs. Results: DXR-BMD decreased in both men and women after the age of 45 years, progressively more so in women. While minimum hip JSW in men remained relatively unaltered throughout life, a marked decline in female minimum hip JSW after 45 years was observed. We found moderate, but highly significant relationships between reduced BMD and reduced hip JSW in women (p < 0.001), adjusted for age and dysplastic joint incongruity. Conclusion: We believe that the present study supports the hypothetical relationship between reduced estrogen levels and hip joint space width reduction in women

The purpose of this study was to determine the effect of sectioning the relevant soft tissues and a TKA on the medial and lateral knee joint gap.

Twelve intact lower extremity cadaveric specimens (mean (SD) age 76.5 (11.6) years) were tested. A custom designed knee tensioner was developed that allowed the separate application of forces to the medial and lateral components of the knee. The distance between the bottom of the load cell and the top of a compression rod was measured with digital calipers (precision = 0.1mm). Loads of 100N and 200N were then applied to each compartment and the resulting displacement was measured. The two loads were applied to the knee in the following conditions: i) All soft tissues intact; ii) an arthrotomy; iii) ACL sectioned; iv) PCL sectioned; v) release of the mid-coronal tissues; and vi) TKA. Finally, tensions were applied for all conditions from 90° to 0° of knee flexion in 30° increments.

There was a significant effect of soft tissue release on the magnitude of the gap at the 100N load application, such that there was an increase in the when the mid-coronal MCL release was performed compared to the intact (2.2mm) and arthrotomy (1.75mm) conditions. With respect to the 200N load application there was a statistically significant tissue release effect, where differences were detected between the mid-coronal MCL release and intact (3.04mm) and arthrotomy conditions (2.31mm). At the 100N load there was a significance increase in the gap compared to the intact knee. There was also a significant condition by knee angle interaction where the gap was approximately 4mm larger following the TKA compared to the intact condition when the knee was flexed at 90°. Furthermore, there was a statistically significant 4.8mm and 3.8mm difference between 90° and 0° and 60° and 0° of knee flexion respectively, for the TKA condition only. At the 200N load application the gap width increased significantly by 2.5mm following the TKA. Finally, there was a significant condition by knee angle interaction where the change in gap width increased significantly from the intact (7.54mm) to the TKA condition (13.88mm) at 90° of knee flexion. There was a statistically significant difference in the TKA condition between 60° and 0° of knee flexion.

Releasing the soft tissues increases the gap between the tibia and femur, when compared to the intact condition, with significance occurring only following the mid-coronal release. Furthermore, the TKA did not return the knee to its intact state as was evident by the significant difference between the TKA and intact conditions. This suggests that the resulting kinematics may not accurately match those pre-surgery resulting in un-physiological motion patterns and the possibility of early failure and revision.

Purpose. It is well known that meniscus extrusion is associated with structural progression of knee OA. However, it is unknown whether medial meniscus extrusion promotes cartilage loss in specific femorotibial subregions, or whether it is associated with a increase in cartilage thickness loss throughout the entire femorotibial compartment. We applied quantitative MRI-based measurements of subregional cartilage thickness (change) and meniscus position, to address the above question in knees with and without radiographic joint space narrowing (JSN). Methods. 60 participants with unilateral medial OARSI JSN grade 1–3, and contralateral knee OARSI JSN grade 0 were drawn from the Osteoarthritis Initiative. Manual segmentation of the medial tibial and weight-bearing medial femoral cartilage was performed, using baseline and 1-year follow-up sagittal double echo steady-state (DESS) MRI, and proprietary software (Chondrometrics GmbH, Ainring, Germany). Segmentation of the entire medial meniscus was performed with the same software, using baseline coronal DESS images. Longitudinal cartilage loss was computed for 5 tibial (central, external, internal, anterior, posterior) and 3 femoral (central, external, internal) subregions. Meniscus position was determined as the % area of the entire meniscus extruding the tibial plateau medially and the distance between the external meniscus border and the tibial cartilage in an image located 4mm posterior to the central image (a location commonly used for semi-quantitative meniscus scoring). The relationship between meniscus position and cartilage loss was assessed using Pearson (r) correlation coefficients, for knees with JSN and without JSN. Results. The percentage of knees showing a quantitative value of >3mm medial meniscus extrusion was 50% in JSN knees, and only 12% in noJSN knees. The 1-year cartilage loss in the medial femorotibial compartment was 74±182µm (2.0%) in JSN knees, and 26±120µm (0.8%) in noJSN knees. There was a significant correlation between cartilage loss throughout the entire femorotibial compartment (MFTC) and extrusion area in JSN knees but not for noJSN knees. Also, the extrusion distance measured 4mm posterior to the central slice was not significantly correlated with MFTC cartilage loss. The strongest (negative) correlation between meniscus position and subregional femorotibial cartilage loss (r=−0.36) was observed for the external medial tibia. In contrast, no significant relationship was seen in the central tibia. No significant relationship was found in other tibial subregions, except for the anterior medial tibia, but only in JSN knees (r=−0.27). Correlation coefficients for the femoral subregions were generally smaller than those for tibial subregions, with only the internal medial weight-bearing femur attaining statistical significance (r =−0.26). Conclusions. The current results show that the relationship between meniscus extrusion and cartilage loss differs substantially between femorotibial subregions. The correlation was strongest for the external medial tibia, a region that is physiologically covered by the medial meniscus. It was less for other tibial and femoral subregions, including the central medial tibia, a region that exhibited similar rates of cartilage loss as the external subregion. The findings suggest that external tibia may be particularly vulnerable to cartilage tissue loss once the meniscus extrudes and the surface is “exposed” to direct, non-physiological, cartilage-cartilage contact