Microstructural adaptation in trapezial bone due to subluxation of the thumb

Abstract

Although the thumb saddle is one of the most common sites of degenerative osteoarthritis in the hand, little is known about the altered microstructure in osteoarthritic trapezial bones. External forces resulting from subluxation of the carpometacarpal joint of the thumb (CMC I) should provoke microstructural changes in the trapezium. The purpose of this study was to compare the regional differences of the microstructure between osteoarthritic and healthy trapezial bones. Fifteen trapezia harvested from female patients with radiologically and clinically diagnosed saddle joint osteoarthritis (OA) were compared with 15 unaffected controls. Microstructural parameters, such as bone volume ratio (BV/TV), three-dimensional connectivity (Conn.D), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were studied using a microcomputed tomography (microCT) system. While the trapezial height in OA was 22% less, the sclerotic subchondral bone layer thickness was 50% higher in OA compared with the control group (p < 0.001). In the OA group there was a 42% higher bone volume ratio (p 0.001), an 18% increase in Tb.Th (p ¼ 0.006), and a 10% greater Tb.N (p ¼ 0.034) compared with the control group. Although in both groups BV/TV was significantly lower in the radial region, the radial column showed the highest relative increase in bone volume and structure compared with the control group (þ67% BV/TV, þ20% Tb.Th, þ23% Tb.N). The reinforcement of the bony microstructure in CMC I OA, especially at the radial side, is a sign for bone adaptation reacting to radially shifted joint forces. This has to be considered during the development of new prosthetic alternatives. ß

The 2014 ABJS Nicolas Andry Award: The Puzzle of the Thumb: Mobility, Stability, and Demands in Opposition

“…The expansile dish pattern, in contrast, had significant rimming osteophytes and loose bodies. Surgical inspection did not reveal metacarpal dysmorphology with the dish pattern, other than extrinsic osteophytes and joint eburnation in the cases of dysplastic dish shape, similar to other reports [79,80,86,107]. This is unlike posttraumatic arthritis of a Rolando fracture, where the metacarpal is fractured and becomes dysplastic yet typically the trapezial shape is unaltered.…”

“…3 studied with micro-CT in normal and arthritic specimens demonstrated higher trabecular presence in the ulnar column of subchondral bone, with increased volume in the arthritic radial column [80].…”

Trapezium Trabecular Morphology in Carpometacarpal Arthritis

“…Current literature supports noteworthy trabecular remodeling primarily in the trapezium rather than the first metacarpal in CMC joint arthritis (13, 15, 17, 20, 24). Recent studies using high-resolution computed tomography (micro-CT) have correlated changes in trabecular bone morphology with osteoarthritis (20, 25–27). These studies have demonstrated substantial deterioration in the 3-dimensional architecture of cancellous bone, leading to unfavorable alteration in mechanical properties.…”

“…Preferential wear of the volar surface of the trapezium, however, is the most common pattern of degeneration reported in the literature (9, 10, 13, 17, 18). Similarly, the mechanics of abnormal loading and wear of the metacarpal upon the trapezium, and the bony remodeling of this process, are postulated (19,20) but poorly understood; few in vivo studies of CMC joint kinematics exist (21,22). …”

Comparison of Two Uncemented Trapezio-Metacarpal Cups: A Finite Element Study

“…Other finite element studies of the carpus have assigned a cortical thickness of 1 mm to the carpal bones including the trapezium. 9 , 16 Nufer et al 17 harvested 15 trapezia during trapeziectomy procedures and compared these with 80 cadaver hands without radiological signs of osteoarthritis or osteoporosis. High resolution micro CT demonstrated that the osteoarthritic trapezia had lost length, but had a 50% thicker subcortical bone layer compared to controls.…”