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Background: The variation in articular cartilage thickness (ACT) in healthy knees is difficult to quantify and therefore poorly documented. Our aims are to (1) define how machine learning (ML) algorithms can automate the segmentation and measurement of ACT on magnetic resonance imaging (MRI) (2) use ML to provide reference data on ACT in healthy knees, and (3) identify whether demographic variables impact these results., Methods: Patients recruited into the Osteoarthritis Initiative with a radiographic Kellgren-Lawrence grade of 0 or 1 with 3D double-echo steady-state MRIs were included and their gender, age, and body mass index were collected. Using a validated ML algorithm, 2 orthogonal points on each femoral condyle were identified (distal and posterior) and ACT was measured on each MRI. Site-specific ACT was compared using paired t-tests, and multivariate regression was used to investigate the risk-adjusted effect of each demographic variable on ACT., Results: A total of 3910 MRI were included. The average femoral ACT was 2.34 mm (standard deviation, 0.71; 95% confidence interval, 0.95-3.73). In multivariate analysis, distal-medial (-0.17 mm) and distal-lateral cartilage (-0.32 mm) were found to be thinner than posterior-lateral cartilage, while posterior-medial cartilage was found to be thicker (0.21 mm). In addition, female sex was found to negatively impact cartilage thickness (OR, -0.36; all values: P < .001)., Conclusion: ML was effectively used to automate the segmentation and measurement of cartilage thickness on a large number of MRIs of healthy knees to provide normative data on the variation in ACT in this population. We further report patient variables that can influence ACT. Further validation will determine whether this technique represents a powerful new tool for tracking the impact of medical intervention on the progression of articular cartilage degeneration., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: The information content of knee bone scintigraphy was evaluated, including pattern, localisation and intensity of retention relative to radiographic features of knee osteoarthritis, knee alignment and knee symptoms., Methods: A total of 308 knees (159 subjects) with symptomatic and radiographic knee osteoarthritis of at least one knee was assessed by late-phase (99m)Technetium methylene disphosphonate bone scintigraph, fixed-flexion knee radiograph, full limb radiograph for knee alignment and for self-reported knee symptom severity. Generalised linear models were used to control for within-subject correlation of knee data., Results: The compartmental localisation (medial vs lateral) and intensity of knee bone scan retention were associated with the pattern (varus vs valgus) (p<0.001) and severity (p<0.001) of knee malalignment and localisation and severity of radiographic osteoarthritis (p<0.001). Bone scan agent retention in the tibiofemoral, but not patellofemoral, compartment was associated with severity of knee symptoms (p<0.001) and persisted after adjusting for radiographic osteoarthritis (p<0.001)., Conclusion: To the authors' knowledge, this is the first study describing a relationship between knee malalignment, joint symptom severity and compartment-specific abnormalities by bone scintigraphy. This work demonstrates that bone scintigraphy is a sensitive and quantitative indicator of symptomatic knee osteoarthritis. Used selectively, bone scintigraphy is a dynamic imaging modality that holds great promise as a clinical trial screening tool and outcome measure.

This study seeks to evaluate the clinical outcomes of a second primary total knee arthroplasty in patients whose initial (contralateral) primary total knee arthroplasty was complicated by stiffness. We retrospectively compared the preoperative and postoperative range of motion and Knee Society Scores from a study group of 15 patients with an age-matched control group. Statistical analysis did not reveal a significant difference in final postoperative range of motion or Knee Society Scores between the 2 groups. However, there was a statistically significant higher rate of closed manipulation in the study group. Therefore, although the study group did show a higher rate of early stiffness, eventual functional outcome was comparable with a nonstiffness control group.

Objective: To evaluate the dehydroascorbate (DHA) transport mechanisms in human chondrocytes., Methods: The transport of L-(14)C-DHA in human chondrocytes was analyzed under various conditions, including the use of RNA interference (RNAi), to determine the role of glucose transporter 1 (GLUT-1) and GLUT-3 in L-14C-DHA transport and to evaluate the effects of physiologically relevant oxygen tensions on L-14C-DHA transport. In order to estimate the contributions of reduced ascorbic acid (AA) and DHA to intracellular ascorbic acid (Asc), the quantities of AA and DHA were measured in synovial fluid samples from osteoarthritis (OA) patients and compared with the reported levels in rheumatoid arthritis (RA) patients., Results: DHA transport in human chondrocytes was glucose-sensitive, temperature-dependent, cytochalasin B-inhibitable, modestly stereoselective for L-DHA, and up-regulated by low oxygen tension. Based on the RNAi results, GLUT-1 mediated, at least in part, the uptake of DHA, whereas GLUT-3 had a minimal effect on DHA transport. DHA constituted a mean 8% of the total Asc in the synovial fluid of OA joints, in contrast to 80% of the reported total Asc in RA joints., Conclusion: We provide the first evidence that chondrocytes transport DHA via the GLUTs and that this transport mechanism is modestly selective for L-DHA. In the setting of up-regulated DHA transport at low oxygen tensions, DHA would contribute 26% of the total intracellular Asc in OA chondrocytes and 94% of that in RA chondrocytes. These results demonstrate that DHA is a physiologically relevant source of Asc for chondrocytes, particularly in the setting of an inflammatory arthritis, such as RA.

Objective: To compare the knee-alignment angle from a full-limb radiograph (mechanical axis) with the anatomic-axis angle as measured by physical examination using a goniometer and by 2 other radiographic methods., Methods: The knee-alignment angle was measured in 114 knees of 57 subjects who had radiographic osteoarthritis (OA), with a Kellgren/Lawrence grade of >/=1 in at least one knee. The mechanical axis was defined as the angle formed by the intersection of 2 lines, one from the center of the head of the femur to the center of the tibial spines, and a second from the center of the talus to the center of the tibial spines. The anatomic axis was defined as the angle formed by 2 lines, each originating from a point bisecting the femur and tibia and converging at the center of the tibial spine tips. The anatomic-axis angle was measured by 3 methods: 1) physical examination using a goniometer, 2) a posteroanterior (PA) fixed-flexion knee radiograph (anatomic(PA) axis), and 3) an anteroposterior (AP) full-limb radiograph (anatomic(AP) axis)., Results: Significant correlations were found between the mechanical-axis angle and the anatomic-axis angle measured by each of the 3 methods: by goniometer (r = 0.70, P < 0.0001), by anatomic(PA) axis (r = 0.75, P < 0.0001), and by anatomic(AP) axis (r = 0.65, P < 0.0001). The anatomic axis was offset a mean 4.21 degrees valgus from the mechanical axis (3.5 degrees in women, 6.4 degrees in men), which was consistent across all methods., Conclusion: Knee alignment assessed clinically by goniometer or measured on a knee radiograph is correlated with the angle measured on the more cumbersome and costly full-limb radiograph. These alternative measures have the potential to provide useful information regarding the risk of progression of knee OA when a full-limb radiograph is not available.

This study examined the hypothesis that meniscal allograft transplantation serves a "chondroprotective" role and prevents the histological and biomechanical changes of the articular cartilage following meniscectomy. Skeletally mature mongrel dogs underwent total medial meniscectomy and received either a fresh meniscal allograft ( n=10) or no further treatment ( n=10). Semiquantitative histology and biomechanical analysis of the femoral articular cartilage was used to assess cartilage pathology 12 weeks following surgery. Histological analysis showed significant changes in cartilage structure that did not differ between the meniscectomy and allograft transplantation groups. Similarly, the tensile modulus of the surface zone cartilage was significantly lower than that in unoperated controls following either meniscectomy or allograft transplantation. A significant correlation was observed between the biomechanical and histological changes, suggesting that degenerative changes in cartilage structure and mechanical function are interrelated. Our findings do not support the hypothesis that meniscal allograft transplantation provides chondroprotection of the femoral condyle and also suggest that it does not lead to increased degenerative changes.

The purposes of this study were to document the histological changes present in the tibial plateaus 12 weeks after complete medial meniscectomy in dogs and to determine if synovial lavage fluid biomarker levels are predictive of the severity of joint damage. Twelve adult dogs underwent complete unilateral medial meniscectomy and synovial lavage fluid biomarker levels, including cartilage oligomeric matrix protein (COMP), keratan sulfate (5D4). 3B3(-), and 3B3(+), were measured serially at 4-week intervals. The dogs were euthanized 12 weeks after surgery and each medial and lateral tibial plateau from the meniscectomized and contralateral knees was graded histologically. Histological data were analyzed using principal components analysis, which resulted in 4 factors that explained 70% of the variation in the data. Factor 2 (weighted most heavily by subchondral bone thickness) and Factor 3 (representative of articular cartilage damage) were significantly affected by compartmental site (P < 0.01 for both). Both of these factors were highest in the medial tibial plateau of the meniscectomized knee, and Factor 3 was significantly higher in this site than in the medial tibial plateau of the contralateral knee (P < 0.01). Peak levels of all 4 synovial lavage fluid biomarkers occurred at 4 weeks post-meniscectomy and 4-week minus baseline levels of all biomarkers were significantly correlated with the Factor 3 scores. This study demonstrates that significant articular cartilage damage occurs relatively quickly following complete medial meniscectomy in dogs and establishes the content and criterion validity for these synovial fluid lavage biomarkers in canine meniscectomy as surrogate measures of articular cartilage damage.

Knee arthrodesis can enable limb salvage in patients with disability secondary to trauma, infected total knee arthroplasty, pyarthrosis, and other complications. Historically, intramedullary nailing has resulted in the highest overall knee fusion rates. However, intramedullary nailing is relatively contraindicated in the presence of active infection. Nineteen patients who underwent knee arthrodesis with circular external fixation were studied retrospectively. Postoperative radiographs were evaluated for evidence of bony fusion, which was defined as trabecular bridging between the femur and tibia. Patients were interviewed and graded using the functional assessment portion of the Knee Society clinical rating system. Fusion was successful in 13 of 19 (68%) patients. Overall, patients spent an average of 4 months 8 days wearing the circular external fixator. Average time to radiographic and clinical evidence of arthrodesis (defined as lack of motion across the fusion site) was 4 months 18 days. No patient with successful fusion considered himself or herself housebound. All but one of these patients require some form of assistive device for ambulation. Complications occurred in 16 of 19 (84%) patients overall. Superficial pin tract infection (55%) and nonunion (32%) were the most common. Circular external fixation is an effective method for obtaining knee arthrodesis in patients who are not good candidates for intramedullary nailing.

This study evaluates the three-dimensional contour of the intercondylar notch of the knee along its entire length. Forty-one distal femora, from human cadavers with a mean age of 45 years (range: 23 to 70 years) at the time of death were studied. The specimens were selected for the absence of previous surgery or degenerative changes including osteophyte formation. Measurements were taken from a cast of the distal femur. Transverse sections of the cast were cut every 3 mm in a plane perpendicular to the long axis of the femur. Within this plane, the epicondylar width, the condylar height, the notch height, and the minimum and maximum width of the notch were measured. The ratios between these measurements were calculated and subjected to analysis of variance. The notch width increased gradually from a mean of 1.8 cm at the distal aspect to a mean of 2.3 cm at the most proximal portion. The notch height increased from a mean value of 1.8 cm at the distal-most portion to a maximum of 2.4 cm at 1.8 cm from the distal-most portion of the notch. The height then decreased to a mean value of 1.3 cm at the most proximal portion of the notch. The epicondylar width:notch width ratio ranged from 4.70 distally to 4.25 proximally. These results indicate that the notch is narrowest distally and widens proximally, and the notch height is greatest in the midportion and decreases proximally and distally.

The purpose of this paper is to define the use of the extraarticular, lateral reconstruction in the spectrum of patients with cruciate deficiency. A review was conducted of 112 consecutive patients with a MacIntosh-type iliotibial band transfer done between 1972 and 1986. Fifty-six of the patients had a partial or complete meniscectomy, and 24% had failed a previous extraarticular procedure. Eighty-one percent were men, with a mean age of 23. Twenty-five percent of the patients had radiographic degenerative changes at the knee at the outset. Ninety-eight percent had an anterior drawer of 1+ or greater; 97% had a pivot shift greater than trace. All patients had symptomatic knee instability. Seventy-seven of the 112 patients (69%) were available for followup (range, 24 months to 15.5 years; median, 7.6). Twenty-three patients (21%) returned for examination, KT-1000 and Cybex testing, and radiographs. An additional 54 patients (48%) were seen by their local physicians or returned a detailed questionnaire that included the Cincinnati knee rating scale. At final followup, 38% complained of some knee instability, 36% had recurrent effusions, 61% had intermittent pain, 79% had radiographic gonarthrosis, and 25% had undergone additional surgery. Forty-two percent had a positive Lachman after surgery, and only 15% had a pivot shift. The mean knee score was 81.1. Previous extraarticular anterior cruciate ligament reconstruction, meniscectomy, and generalized ligamentous laxity were associated with a significant decrement in the knee rating (P = 0.05). Ligamentous laxity strongly correlated with symptoms of giving way.(ABSTRACT TRUNCATED AT 250 WORDS)