Osteophyte growth in early thumb carpometacarpal osteoarthritis.

OBJECTIVE: Osteophyte formation is a critical part of the degeneration of a joint with osteoarthritis (OA). While often qualitatively described, few studies have succeeded in quantifying osteophyte growth over time. Using computed tomography (CT) image data from a longitudinal, observational study of thumb carpometacarpal (CMC) OA, our aim was to quantify osteophyte growth volume and location over a three-year period in men and women. METHOD: Ninety patients with early thumb OA were recruited and assessed at baseline, 1.5 years, and 3 years with CT imaging. Osteophyte volume and location on the trapezium and first metacarpal were determined using a library of 46 healthy subjects as a nonarthritic reference database. RESULTS: There was a significant increase in osteophyte volume for women and men over the three-year follow-up in the trapezium (86.8 mm3-120.5 mm3 and 165.1 mm3-235.3 mm3, means respectively) and in the proximal metacarpal (63 mm3-80.4 mm3, and 115.8 mm3-161.7 mm3, respectively). The location of osteophyte initiation and growth was consistent across subjects and was located in non-opposing regions on the trapezium and first metacarpal. Osteophyte growth occurred about the radial and ulnar margins of the trapezial facet, while on the proximal metacarpal, growth occurred principally about the volar and dorsal margins of the facet. CONCLUSION: Osteophyte growth occurred in early thumb osteoarthritis over three years. Growth was localized in specific, non-opposing regions on the trapezium and metacarpal, raising intriguing questions about the triggers for their formation, whether the mechanisms are mechanical, biological or a combination of both.

Early morphologic changes in trapeziometacarpal joint bones with osteoarthritis.

OBJECTIVE: Characterising the morphological differences between healthy and early osteoarthritic (EOA) trapeziometacarpal (TMC) joints is important for understanding osteoarthritis onset, and early detection is important for treatment and disease management. This study has two aims: first, to characterise morphological differences between healthy and EOA TMC bones. The second aim was to determine the efficacy of using a statistical shape model (SSM) to detect early signs of osteoarthritis (OA). METHODS: CT image data of TMC bones from 22 asymptomatic volunteers and 47 patients with EOA were obtained from an ongoing study and used to generate a SSM. A linear discriminant analysis (LDA) classifier was trained on the principal component (PC) weights to characterise features of each group. Multivariable statistical analysis was performed on the PC to investigate morphologic differences. Leave-one-out classification was performed to evaluate the classifiers performance. RESULTS: We found that TMC bones of EOA subjects exhibited a lower aspect ratio (P = 0.042) compared with healthy subjects. The LDA classifier predicted that protrusions (up to 1.5 mm) at the volar beak of the first metacarpal were characteristic of EOA subjects. This was accompanied with widening of the articular surface, deepening of the articular surface, and protruding bone growths along the concave margin. These characteristics resulted in a leave-one-out classification accuracy of 73.9% (95% CI [61.9%, 83.8%]), sensitivity of 89.4%, specificity of 40.9%, and precision of 75.9%. CONCLUSION: Our findings indicate that morphological degeneration is well underway in the EOA TMC joint, and shows promise for a clinical tool that can detect these features automatically.

Functional kinematics of the wrist.

The purpose of this article is to review past and present concepts concerning functional kinematics of the healthy and injured wrist. To provide a context for students of the wrist, we describe the progression of techniques for measuring carpal kinematics over the past century and discuss how this has influenced today's understanding of functional kinematics. Next, we provide an overview of recent developments and highlight the clinical relevance of these findings. We use these findings and recent evidence that supports the importance of coupled motion in early rehabilitation of radiocarpal injuries to develop the argument that coupled motion during functional activities is a clinically relevant outcome; therefore, clinicians should develop a framework for its dynamic assessment. This should enable a tailored and individualized approach to the treatment of carpal injuries.

The effects of partial carpal fusions on wrist range of motion.

UNLABELLED: The objective of this investigation was to evaluate the effects of different partial wrist fusions on wrist motion. A total of 20 cadaveric wrists were tested in the intact state and after undergoing either a four-corner fusion or 2- and 3-bone fusion. The moment-rotation behaviour was measured in 24 directions of wrist motion about the forearm axis. The 2- and 3-bone fusion groups demonstrated increased radial deviation and pure flexion. Pure flexion was decreased in the four-corner fusion group. Radial extension and pure extension were decreased in all treatments compared with normal range of motion. Increasing the number of carpal bones within the fusion construct did not alter the functional axis of the wrist. Essentially equivalent motion is possible with 2-bone, 3-bone and four-corner fusions, with the exceptions of pure flexion and radial deviation. This data may influence surgeons when choosing between treatment methods. LEVEL OF EVIDENCE: N/A.

Men and women have similarly shaped carpometacarpal joint bones.

Characterizing the morphology of the carpometacarpal (CMC) joint bones and how they vary across the population is important for understanding the functional anatomy and pathology of the thumb. The purpose of this paper was to develop a statistical shape model of the trapezium and first metacarpal bones to characterize the size and shape of the whole bones across a cohort of 50. We used this shape model to investigate the effects of sex and age on the size and shape of the CMC joint bones and the articulating surface area of the CMC joint. We hypothesized that women have similar shape trapezium and first metacarpal bones compared to men, following scaling for overall size. We also hypothesized that age would be a significant predictor variable for CMC joint bone changes. CT image data and segmented point clouds of 50 CMC bones from healthy adult men and women were obtained from an ongoing study and used to generate two statistical shape models. Statistical analysis of the principal component weights of both models was performed to investigate morphological sex and age differences. We observed sex differences, but were unable to detect any age differences. Between men and women the only difference in morphology of the trapezia and first metacarpal bones was size. These findings confirm our first hypothesis, and suggest that the women have similarly shaped trapezium and first metacarpal bones compared to men. Furthermore, our results reject our second hypothesis, indicating that age is a poor predictor of CMC joint morphology.

Cognitive effects of one season of head impacts in a cohort of collegiate contact sport athletes.

OBJECTIVE: To determine whether exposure to repetitive head impacts over a single season negatively affects cognitive performance in collegiate contact sport athletes. METHODS: This is a prospective cohort study at 3 Division I National Collegiate Athletic Association athletic programs. Participants were 214 Division I college varsity football and ice hockey players who wore instrumented helmets that recorded the acceleration-time history of the head following impact, and 45 noncontact sport athletes. All athletes were assessed prior to and shortly after the season with a cognitive screening battery (ImPACT) and a subgroup of athletes also were assessed with 7 measures from a neuropsychological test battery. RESULTS: Few cognitive differences were found between the athlete groups at the preseason or postseason assessments. However, a higher percentage of the contact sport athletes performed more poorly than predicted postseason on a measure of new learning (California Verbal Learning Test) compared to the noncontact athletes (24% vs 3.6%; p < 0.006). On 2 postseason cognitive measures (ImPACT Reaction Time and Trails 4/B), poorer performance was significantly associated with higher scores on several head impact exposure metrics. CONCLUSION: Repetitive head impacts over the course of a single season may negatively impact learning in some collegiate athletes. Further work is needed to assess whether such effects are short term or persistent.

High dietary fat and the development of osteoarthritis in a rabbit model.

OBJECTIVE: Osteoarthritis (OA) is associated with obesity, although this relationship remains unclear. Proposed etiologies of OA in obesity include mechanical loading of malaligned joints and possible toxicity of dietary fat. The hypothesis tested in the present study was that increased dietary fat worsens OA in both malaligned and normal joints, detected by biochemical and histological cartilage markers. METHOD: 83 New Zealand white rabbits were divided among two conditions related to OA: bowing of the knee and a 14%kcal vs 47.8%kcal fat diet. Rabbit weights and knee angles were compared throughout the experiment. At 28 and 38 weeks, intra-articular forces were measured, animals sacrificed, and knee cartilage examined for histological changes, glycosaminoglycan content, 35S uptake, and aggrecanase-1 expression. RESULTS: There were no differences in animal weights or intra-articular forces between the two diets. Despite increased fat content in their diet, animals on the 47.8%kcal fat diet did not gain excess weight. Representative histology showed atypical shearing of articular cartilage among animals on the high fat diet. Animals on the 47.8%kcal fat diet had suppression of protein synthesis compared to the 14%kcal fat diet: lower glycosaminoglycan content and aggrecanase-1 expression in all knee compartments at both times, and lower 35S uptake at 38 weeks. CONCLUSION: These results suggest dietary fat, independent of animal weight, results in altered chondrocyte function. Increased dietary fat was associated with changes in rabbit cartilage in vivo and appears to be a risk factor for the development of OA.

Midcarpal hemiarthroplasty for wrist arthritis: rationale and early results.

Midcarpal hemiarthroplasty is a novel motion-preserving treatment for radiocarpal arthritis and is an alternative to current procedures that provide pain relief at the expense of wrist biomechanics and natural motion. It is indicated primarily in active patients with a well-preserved distal row and debilitating arthritic symptoms. By resurfacing the proximal carpal row, midcarpal arthroplasty relieves pain while preserving the midcarpal articulation and the anatomic center of wrist rotation. This technique has theoretical advantages when compared with current treatment options (i.e., arthrodesis and total wrist arthroplasty) since it provides coupled wrist motion, preserves radial length, is technically simple, and avoids the inherent risks of nonunion and distal component failure. The KinematX midcarpal hemiarthroplasty has an anatomic design and does not disrupt the integrity of the wrist ligaments. We have implanted this prosthesis in nine patients with promising early results. The indications for surgery were as follows: scapholunate advanced collapse wrist (three), posttraumatic osteoarthritis (three), inflammatory arthritis (two), and Keinböck disease (one). Prospective data has been collected and the results are preliminary given the infancy of the procedure. The mean follow-up was 30.9 weeks (range: 16 to 56 weeks). The mean Mayo wrist score increased from 31.9 preoperatively to 58.8 (p < 0.05) and the mean DASH score improved significantly from 47.8 preoperatively to 28.7 (p < 0.05). There was a trend toward increased motion but statistical significance was not reached. Two patients required manipulation for wrist stiffness. There was no evidence of prosthetic loosening or capitolunate narrowing. The procedure is simple (average surgical time was 49 minutes) and maintains coupled wrist motion through preservation of the midcarpal articulation. The preliminary data show that it appears safe but considerably longer follow-up is required before conclusions can be drawn as to its durability, reliability, and overall success. The level of evidence for this study is therapeutic level IV (case series).

Quantitative MR imaging using "LiveWire" to measure tibiofemoral articular cartilage thickness.

OBJECTIVE: To assess the reliability and accuracy of manual and semi-automated segmentation methods for quantifying knee cartilage thickness. This study employed both manual and LiveWire-based semi-automated segmentation methods, ex vivo and in vivo, to measure tibiofemoral (TF) cartilage thickness. METHODS: The articular cartilage of a cadaver knee and a healthy volunteer's knee were segmented manually and with LiveWire from multiple 3T MR images. The cadaver specimen's cartilage thickness was also evaluated with a 3D laser scanner, which was assumed to be the gold standard. Thickness measurements were made within specific cartilage regions. The reliability of each segmentation method was assessed both ex vivo and in vivo, and accuracy was assessed ex vivo by comparing segmentation results to those obtained with laser scanning. RESULTS: The cadaver specimen thickness measurements showed mean coefficients of variation (CVs) of 4.16%, 3.02%, and 1.59%, when evaluated with manual segmentation, LiveWire segmentation, and laser scanning, respectively. The cadaver specimen showed mean absolute errors versus laser scanning of 4.07% and 7.46% for manual and LiveWire segmentation, respectively. In vivo thickness measurements showed mean CVs of 2.71% and 3.65% when segmented manually and with LiveWire, respectively. CONCLUSIONS: Manual segmentation, LiveWire segmentation, and laser scanning are repeatable methods for quantifying knee cartilage thickness; however, the measurements are technique-dependent. Ex vivo, the manual segmentation error was distributed around the laser scanning mean, while LiveWire consistently underestimated laser scanning by 8.9%. Although LiveWire offers repeatability and decreased segmentation time, manual segmentation more closely approximates true cartilage thickness, particularly in cartilage contact regions.

Effects of ACL interference screws on articular cartilage volume and thickness measurements with 1.5 T and 3 T MRI.

OBJECTIVE: To assess the effects of interference screws, which are commonly used to surgically fix an anterior cruciate ligament (ACL) graft in the ACL-deficient knee, and magnetic field strength on cartilage volume and thickness measurements with quantitative magnetic resonance imaging (qMRI). METHODS: Five cadaver knees were imaged using a cartilage-sensitive sequence (T1-weighted water-excitation, three-dimensional (3D) fast low-angle shot) on 1.5T and 3T scanners with and without interference screws implanted. The tibiofemoral articular cartilage was segmented and reconstructed from the magnetic resonance images, and volume and thickness measurements were made on the resulting 3D models. RESULTS: Although several load-bearing regions showed significant differences in volume and thickness between magnet strengths, most showed no significant difference between screw conditions. The medial tibial cartilage showed a mean decrease in volume of 5.9% and 8.0% in the presence of interference screws at 3T and 1.5T, respectively. At 3T and 1.5T, the medial tibial cartilage showed a mean decrease in thickness of 7.0% and 12.0%, respectively, in the presence of interference screws. CONCLUSIONS: Caution should be used when interpreting thickness and volume of cartilage at 3T in the presence of interference screws, particularly in the medial tibial compartment. Additionally, 3T and 1.5T qMRI should not be used interchangeably to assess structural changes in tibiofemoral articular cartilage during longitudinal studies.