Imaging the role of biomechanics in osteoarthritis

Association of Decrease in Body Mass Index With Reduced Incidence and Progression of the Structural Defects of Knee Osteoarthritis: A Prospective Multi-Cohort Study

OBJECTIVE

To define the association between change in body mass index (BMI) and the incidence and progression of the structural defects of knee osteoarthritis as assessed by radiography.

METHODS

Radiographic analyses of knees at baseline and at 4-5 years of follow-up were obtained from the following 3 independent cohort studies: the Osteoarthritis Initiative (OAI) study, the Multicenter Osteoarthritis Study (MOST), and the Cohort Hip and Cohort Knee (CHECK) study. Logistic regression analyses using generalized estimating equations, with clustering of both knees within individuals, were used to investigate the association between change in BMI from baseline to 4-5 years of follow-up and the incidence and progression of knee osteoarthritis.

RESULTS

A total of 9,683 knees (from 5,774 participants) in an "incidence cohort" and 6,075 knees (from 3,988 participants) in a "progression cohort" were investigated. Change in BMI was positively associated with both the incidence and progression of the structural defects of knee osteoarthritis. The adjusted odds ratio (OR) for osteoarthritis incidence was 1.05 (95% confidence interval [95% CI] 1.02-1.09), and the adjusted OR for osteoarthritis progression was 1.05 (95% CI 1.01-1.09). Change in BMI was also positively associated with degeneration (i.e., narrowing) of the joint space and with degeneration of the femoral and tibial surfaces (as indicated by osteophytes) on the medial but not on the lateral side of the knee.

CONCLUSION

A decrease in BMI was independently associated with lower odds of incidence and progression of the structural defects of knee osteoarthritis and could be a component in preventing the onset or worsening of knee osteoarthritis.

The influence of K-wire transfixation on proximalization of the first metacarpal after resection suspension interposition arthroplasty

INTRODUCTION

Osteoarthritis of the first carpometacarpal joint is a common degenerative disease and surgical treatment includes resection suspension interposition arthroplasty (RSIA) with or without temporary transfixation of the first metacarpal. One major drawback includes proximalization of the first metacarpal during the postoperative course. Specific data comparing different transfixation techniques in this context is sparse.

MATERIALS AND METHODS

In this retrospective study, we measured the trapezial space ratio (TSR) in 53 hands before and after RSIA to determine the proximalization of the first metacarpal depending on the type of Kirschner (K)-wire transfixation. We, therefore, compared transfixation of the first metacarpal to the scaphoid with one K-wire (1K) to transfixation of the first metacarpal with two K-wires (2K), either to the carpus (2Ka), or to the second metacarpal (2Kb), or to both second metacarpal and carpus (2Kc).

RESULTS

While preoperative TSR did not differ between group 1K and 2K (p = 0.507), postoperative TSR was significantly higher in group 2K compared to 1K (p = 0.003). Comparing subgroups, postoperative TSR was significantly higher in group 2Kc than 1K (p = 0.046), while we found no significant difference comparing either group 2Ka or 2Kb to 1K (p = 0.098; p = 0.159). Neither did we find a significant difference within 2K subgroups, comparing group 2Ka and 2Kb (p = 0.834), 2Ka and 2Kc (p = 0.615), or 2Kb and 2Kc (p = 0.555).

CONCLUSIONS

The results of our study suggest that transfixation with two K-wires should be preferred to transfixation with one K-wire after RSIA. Specifically, transfixation from first to second metacarpal and from first metacarpal to carpus resulted in least proximalization of the first metacarpal postoperatively.

Objectively Measured Physical Activity and Risk of Knee Osteoarthritis

PURPOSE

This study aimed to examine the association between objectively measured physical activity and risk of developing incident knee osteoarthritis (OA) in a community-based cohort of middle-age and older adults.

METHODS

We used data from the Osteoarthritis Initiative, an ongoing prospective cohort study of adults 45 to 83 yr of age at initial enrollment with elevated risk of symptomatic knee OA. Moderate-vigorous physical activity (MVPA) was measured by a uniaxial accelerometer for seven continuous days in two data collection cycles and was categorized as inactive (<10 min·wk), low activity (10-<150 min·wk), and active (≥150 min·wk). Incident knee OA based on radiographic and symptomatic OA and joint space narrowing were analyzed as outcomes over 4 yr of follow-up. Participants free of the outcome of interest in both knees at study baseline were included (sample sizes ranged from 694 to 1331 for different outcomes). We estimated hazard ratio (HR) with 95% confidence intervals (CI).

RESULTS

In multivariate analyses, active MVPA participation was not significantly associated with risk of incident radiographic knee OA (HR = 1.52, 95% CI = 0.68-3.40), symptomatic knee OA (HR = 1.17, 95% CI = 0.44-3.09), or joint space narrowing (HR = 0.87, 95% CI = 0.37-2.06) when compared with inactive MVPA participation. Similar results were found for participants with low activity MVPA.

CONCLUSION

MVPA was not associated with the risk of developing incident knee OA or joint space narrowing over 4 yr of follow-up among Osteoarthritis Initiative participants who are at increased risk of knee OA.

Proximal fibular osteotomy to treat medial compartment knee osteoarthritis: Preoperational factors for short-term prognosis

Objective

The purpose of this study was to determine the association between preoperational factors and patients’ short-term outcome after proximal fibular osteotomy (PFO) and to provide a basis for detailed surgical indication and patient selection.

Methods

This was a retrospective study of patients undergoing PFO between January 2015 and December 2015. Preoperational clinical data including gender, age, duration of disease, visual analogue score (VAS) and American Knee Society (KSS) score were collected. The radiological factors including hip-knee-ankle angle (HKA angle), condyle-plateau angle (CP angle), Kellgren and Lawrence grade (KL grade), joint space width of both compartments and settlement value were also considered. Patients were followed for at 12 months postoperatively. Both clinical and functional KSS scores were obtained. The outcome of interest was divided into clinical outcome and functional outcome. For each, two criteria were defined: satisfaction and significant improvement. Satisfaction is characterized by a KSS clinical or functional score over 70 points (excellent and good results); significant improvement refers to an increase in KSS scores of more than 15 points. Bivariate logistic regression for the association between preoperational factors and outcomes of interest was performed. Multivariable logistic regression analyses were used to detect the independent factors affecting the outcomes.

Results

A total of 84 patients and 111 knees were followed-up. Of these, 17 knees were from males and 94 were from females. The average age was 59.45±8.82 years. The average preoperational VAS score, KSS clinical and functional score were 7.08±1.41 points, 49.14±10.95 points and 44.97±17.71 points, respectively. According to KL grading, there were 17 knees of grade 2, 47 knees of grade 3, and 47 knees of grade 4. In clinical outcomes, there were 51 knees in the satisfaction group and 77 knees in the significant improvement group. In functional outcomes, 43 knees were in the satisfaction group and 76 knees in the significant improvement group. KSS clinical score (OR = 1.134, 95%CI = 1.067–1.205, P = 0.000) was the independent factor associated with clinical satisfaction. Age (OR = 1.072, 95%CI = 1.000–1.150, P = 0.048), VAS score (OR = 1.679, 95%CI = 1.041–2.706, P = 0.033), KSS clinical (OR = 1.072, 95%CI = 1.005–1.144, P = 0.034) and functional (OR = 1.100, 95%CI = 1.044–1.159, P = 0.000) score, HKA angle (OR = 1.345, 95%CI = 1.119–1.617, P = 0.002) and settlement value (OR = 7.540, 95%CI = 1.307–43.484, P = 0.024) were the independent factors associated with functional satisfaction. KSS clinical (OR = 0.905, 95%CI = 0.850–0.963, P = 0.002) score, CP angle (OR = 0.760, 95%CI = 0.593–0.973, P = 0.030) and medial joint space width (OR = 0.001, 95%CI = 0.000–0.107, P = 0.003) were the independent factors associated with significant clinical improvement; VAS score (OR = 1.582, 95%CI = 1.042–2.402, P = 0.031), KSS functional (OR = 0.888, 95%CI = 0.838–0.942, P = 0.000) score, HKA angle (OR = 1.292, 95%CI = 1.101–1.518, P = 0.002) and settlement value (OR = 9.990, 95%CI = 1.485–67.197, P = 0.018) were the independent factors associated with significant functional improvement.

Conclusions

The independent factors affecting postoperative clinical outcome after PFO were KSS clinical score, CP angle and medial joint space width. In addition, the independent factors that influenced functional outcome included age, VAS score, KSS score, HKA angle and settlement value. As objective radiological evidence, HKA angle and settlement value could be used as an important basis for patient selection for PFO.

BDKRB2 +9/-9 bp polymorphisms influence BDKRB2 expression levels and NO production in knee osteoarthritis

The bradykinin B2 receptor (BDKRB2) plays a key role in the inflammation process of osteoarthritis. Nitric oxide has also long been considered to be a catabolic factor that contributes to inflammatory response and the osteoarthritis disease pathology. Several studies have reported that the BDKRB2 +9/-9 bp polymorphisms are associated with transcription of the receptor. However, the roles of BDKRB2 polymorphisms in inflammation in osteoarthritis remain unclear. This study enrolled 156 subjects with primary knee osteoarthritis and 58 healthy volunteers. BDKRB2 polymorphisms were genotyped, and the mRNA and protein levels of BDKRB2 in synovial tissues from osteoarthritis patients were measured by quantitative real-time polymerase chain reaction and western blot analysis, respectively. Nitric oxide production in serum from patients with osteoarthritis was measured using a nitric oxide assay kit. We found that the mean BDKRB2 mRNA levels were significantly higher in Kallgren-Lawrence grade-4 osteoarthritis patients than patients with lower grade osteoarthritis. The +9/-9 bp polymorphisms significantly affected the BDKRB2 mRNA and protein expression levels in synovial tissues from osteoarthritis subjects. Osteoarthritis patients with +9/-9 and -9/-9 genotypes had higher BDKRB2 expression levels in synovial tissue and nitric oxide production in serum. Moreover, positive correlation was found between the BDKRB2 levels in synovial tissue and nitric oxide production. Compared with health controls, significant increases of nitric oxide production in osteoarthritis were detected which were associated with increasing severity of osteoarthritis. Multiple linear regression analysis (adjusted for gender and age) showed serum nitric oxide level was positively associated with BDKRB2 polymorphism and Kallgren-Lawrence grade and was inversely associated with obesity. Our findings showed that the BDKRB2 +9/-9 bp polymorphisms affected the gene expression and nitric oxide production, which were associated with radiographic severity of osteoarthritis, suggesting that the BDKRB2 +9/ -9 bp polymorphisms may act as a genetic modulator of osteoarthritis, and play an essential role in inflammatory process in osteoarthritis.

Radiographic measures of settlement phenomenon in patients with medial compartment knee osteoarthritis

In this study, we proposed for the first time the theory of "settlement phenomenon" in tibial plateau and carefully explored the role of settlement of tibial plateau in the occurrence and progression of medial compartment knee osteoarthritis (OA) through investigating the relationship between the degree of settlement and the radiographic severity of OA. One hundred twenty-seven patients with knee medial compartment OA were recruited and examined with weight-bearing radiographs of the entire lower limb. The radiographic severity of OA was evaluated using the Kellgren and Lawrence (KL) grading methods. The settlement value, hip-knee-ankle angle, minimum medial joint space width, and condylar plateau angle were measured at the same time. The settlement value increases with the upgrading of KL grades (r = 0.352, P < 0.001) and is significantly correlated with the changes of hip-knee-ankle angle, minimum medial joint space width, and condylar plateau angle (r = -0.527, -0.271, and 0.415, P < 0.001, respectively). These results suggest that the settlement of tibial plateau could be an evaluable indicator of medial compartment knee OA and be used in the early diagnosis and progression of OA.

Thumb carpometacarpal joint congruence during functional tasks and thumb range-of-motion activities

Joint incongruity is often cited as a possible etiological factor for the high incidence of thumb carpometacarpal (CMC) joint osteoarthritis (OA) in older women. There is evidence suggesting that biomechanics plays a role in CMC OA progression, but little is known about how CMC joint congruence, specifically, differs among different cohorts. The purpose of this in vivo study was to determine if CMC joint congruence differs with sex, age, and early stage OA for different thumb positions. Using CT data from 155 subjects and a congruence metric that is based on both articular morphology and joint posture, we did not find any differences in CMC joint congruence with sex or age group, but found that patients in the early stages of OA exhibit lower congruence than healthy subjects of the same age group.

Polar histograms of curvature for quantifying skeletal joint shape and congruence

The effect of articular joint shape and congruence on kinematics, contact stress, and the natural progression of joint disease continue to be a topic of interest in the orthopedic biomechanics literature. Currently, the most widely used metrics of assessing skeletal joint shape and congruence are based on average principal curvatures across the articular surfaces. Here we propose a method for comparing articular joint shape and quantifying joint congruence based on three-dimensional (3D) histograms of curvature--shape descriptors that preserve spatial information. Illustrated by experimental results from the trapeziometacarpal joint, this method could help unveil the interrelations between joint shape and function and provide much needed insight for the high incidence of osteoarthritis (OA)--a mechanically mediated disease whose onset has been hypothesized to be precipitated by joint incongruity.

The morphology of the thumb carpometacarpal joint does not differ between men and women, but changes with aging and early osteoarthritis

The high prevalence of thumb carpometacarpal (CMC) joint osteoarthritis (OA) in women has been previously linked to the articular morphology of the trapezium. Studies report conflicting results on how the articular shapes of male and female trapezia compare to one another, however, mainly because their findings are based on data from older cadaveric specimens. The purpose of this in vivo study was to dissociate the effect of sex from that of aging and early OA by using cohorts of healthy young and healthy older subjects, as well as patients with early stage OA. Computed tomography scans from 68 healthy subjects and 87 arthritic subjects were used to obtain 3-D bone models. The trapezial and metacarpal articular surfaces were manually delineated on scaled bone models and compared between sex, age, and health groups by using polar histograms of curvature and average curvatures. We found no sex-related differences, but significant age-group and health-group differences, in the articular surfaces of both bones. Older healthy subjects had higher curvature in the concave and lower curvature in the convex directions of both the trapezial and metacarpal saddles than healthy young subjects. Subjects with early OA had significantly different metacarpal and trapezial articular shapes from healthy subjects of the same age group. These findings suggest that aging and OA affect the articular shape of the CMC joint, but that, in contrast to previously held beliefs, inherent sex differences are not responsible for the higher incidence of CMC OA in women.

The morphology of the thumb carpometacarpal joint does not differ between men and women, but changes with aging and early osteoarthritis

The high prevalence of thumb carpometacarpal (CMC) joint osteoarthritis (OA) in women has been previously linked to the articular morphology of the trapezium. Studies report conflicting results on how the articular shapes of male and female trapezia compare to one another, however, mainly because their findings are based on data from older cadaveric specimens. The purpose of this in vivo study was to dissociate the effect of sex from that of aging and early OA by using cohorts of healthy young and healthy older subjects, as well as patients with early stage OA. Computed tomography scans from 68 healthy subjects and 87 arthritic subjects were used to obtain 3-D bone models. The trapezial and metacarpal articular surfaces were manually delineated on scaled bone models and compared between sex, age, and health groups by using polar histograms of curvature and average curvatures. We found no sex-related differences, but significant age-group and health-group differences, in the articular surfaces of both bones. Older healthy subjects had higher curvature in the concave and lower curvature in the convex directions of both the trapezial and metacarpal saddles than healthy young subjects. Subjects with early OA had significantly different metacarpal and trapezial articular shapes from healthy subjects of the same age group. These findings suggest that aging and OA affect the articular shape of the CMC joint, but that, in contrast to previously held beliefs, inherent sex differences are not responsible for the higher incidence of CMC OA in women.

OPN gene polymorphisms influence the risk of knee OA and OPN levels in synovial fluid in a Chinese population

INTRODUCTION

A body of studies suggests the role of osteopontin (OPN) in onset and development of osteoarthritis (OA), however, the association between OPN polymorphisms and OA susceptibility as well as its clinical features has not been reported.

METHODS

A total of 750 patients with primary knee OA and 794 healthy volunteer were enrolled as controls. Both OA and control groups were interviewed to obtain demographic and clinical data. Three polymorphisms of OPN gene, namely, -156GG/G, -443C/T and -66T/G were determined. The levels of the full length and the thrombin-cleaved OPN in synovial fluid (SF) from OA subjects were measured.

RESULTS

We found the polymorphisms of the -443C/T and the -66/T/G were significantly associated with the OA risk and the radiographic severity. The -443TT and -66GG showed protective effect against developing OA and were associated with lower Kellgren-Lawrence grade. Besides, the polymorphisms of -443C/T and -66T/G significantly affected the thrombin-cleaved OPN levels in SF from OA subjects. Subjects with -443TT and -66GG genotypes had lower thrombin-cleaved OPN levels in SF. The thrombin-cleaved OPN levels in SF were positively correlated to the radiographic severity of OA.

CONCLUSIONS

Our findings suggest that certain OPN gene polymorphisms may be used as molecular markers for the susceptibility and severity of OA.

Rapidly progressive osteoarthritis: biomechanical considerations

An underlying hypothesis for rapid cartilage loss in patients with osteoarthritis (OA) is that perturbation from normal joint mechanics produces locally high biomechanical strains that exceed the material properties of the tissue, leading to rapid destruction. Several imaging findings are associated with focally high biomechanical forces and thus are potential candidates for predictive biomarkers of rapid OA progression. This article focuses on 3 aspects of knee biomechanics that have potential magnetic resonance imaging correlates, and which may serve as prognostic biomarkers: knee malalignment, meniscal dysfunction, and injury of the osteochondral unit.

Effects of an intensive weight loss program on knee joint loading in obese adults with knee osteoarthritis

OBJECTIVE

To determine the effect of an intensive weight loss program on knee joint loads during walking in obese patients with knee osteoarthritis (OA).

METHODS

Participants included 157 obese knee OA patients that underwent a 16-week dietary intervention. Three-dimensional gait analyses were performed before and after the intervention at the participants' freely chosen walking speed. Knee joint compression forces, axial impulses, knee flexion angle and frontal and sagittal plane knee moments were calculated to determine the biomechanical effects of the weight loss.

RESULTS

157 subjects (89% of the initial cohort) completed the 16-week intervention. The average weight loss of 13.7 kg (P<.0001) corresponded to 13.5% of the baseline body weight. The weight loss resulted in a 7% reduction in knee joint loading, a 13% lower axial impulse, and a 12% reduction in the internal knee abductor moment (KAM). There were no clear effects on sagittal plane knee moments or peak knee flexion angle. Linear regression analyses adjusted for changes in walking speed showed that for every 1 kg in weight loss, the peak knee load was reduced by 2.2 kg. Thus, every kilo reduction in body weight was related to more than twice the reduction in peak knee force at a given walking speed.

CONCLUSION

Weight loss is an excellent short-term investment in terms of joint loading for patients with combined obesity and knee OA. The effects of sustained weight loss on disease progression and symptoms in relation to biomechanical factors remain to be shown.