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.

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.

Neurolysis of the distal superficial radial nerve for dysaesthesia due to nerve tethering.

The subcutaneous course of the superficial radial nerve over the radial border of the wrist and hand renders it very susceptible to injury. Both traumatic and iatrogenic injury can produce tethering of this nerve, presenting as dysaesthesia. This study was designed to evaluate the efficacy of neurolysis of the distal superficial radial nerve for this condition. Twenty-five cases of tethered superficial radial nerves underwent neurolysis. At final follow-up (mean 3.5 years), fourteen cases reported symptomatic resolution while eleven continued to experience dysaesthesia. Intra-operatively, evidence of external abnormality, scarring, or compression was identified in only six cases, and its presence did not correlate with symptomatic outcome. Although the majority of patients were improved postoperatively, the success rate was lower than anticipated. Therefore, while neurolysis of the superficial radial nerve offers the opportunity for pain relief, it does not reliably produce success.

[NeuFlex Silastic implant in metacarpophalangeal joint arthroplasty]. / Metakarpophalangeale Arthroplastik mit der NeuFlex-Silastikprothese.

The NeuFlex joint implant is, like the Swanson prosthesis, a silicone-spacer-implant for metacarpophalangeal arthroplasty in rheumatoid arthritis or osteoarthritis. The implant design differs essentially through a preformed, 30 degrees anatomically neutral angle and palmar lying movement center, which reduces strain across the hinge by 35%. The Swanson prosthesis is straight with a dorsal lying movement center. The advantage of this new design is an improved overall function arc and range of movement in the MCP-joint with a better grip-function. Results of simulator and laboratory tests are presented and interpreted. In 50 patients (168 MCP-joints), early results show an average functional arc of movement of 61 degrees and an average extensor lag of 12 degrees. The 30 degrees pre-bend angle, corresponding to the normal resting angle of the hand, and the improved flexor tendon excursion and moment arm appear to be the main reasons for the substantially improved flexion following use of the NeuFlex device.