Radiographic features of hand osteoarthritis in adult Kashin-Beck Disease (KBD): the Yongshou KBD study

Abstract

Objective: Kashin-Beck Disease (KBD) is a rare and severe osteoarthropathy endemic to China. We evaluated the frequency and patterns of hand radiographic osteoarthritis (rOA) in adults with and without KBD.

Methods: Han Chinese (N = 438) from Yongshou County of central China underwent right hand radiography for determining case status. Presence of KBD was based on characteristic radiographic deformities of articular ends of bones including articular surface depression, carpal crowding, any subchondral bone deformities in the proximal end of phalanges or first metacarpal bone, or the distal ends of metacarpal bones 2-5, and any bony enlargement with deformity of the distal ends of phalanges. Hand rOA severity was determined by osteophyte (OST), joint space narrowing (JSN), and Kellgren and Lawrence (KL) grades.

Results: This study included 127 KBD and 311 non-KBD adults of similar mean age (39 years) and body mass index (BMI) (21 kg/m(2)). Inter- and intra-rater reliability for radiographic determination of case status and rOA features was high (kappa 0.72-0.96). Compared to non-KBD, KBD adults had significantly more severe hand rOA of the thumb, distal interphalangeal (DIP), proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints. Only KBD adults had end-stage carpometacapal (CMC) disease. In KBD, DIPs and PIPs were more affected than MCPs and the frequency of OSTs was significantly higher in PIPs than DIPs.

Conclusions: Compared with age-matched adults from the same area and farming occupation, KBD hand rOA was more widespread and severe, particularly of PIPs and CMCs. The ability to differentiate adult KBD from non-KBD hand rOA will facilitate genetic analyses of the vast majority of affected individuals.

Keywords: Diagnosis; Hand; Kashin-Beck Disease; Osteoarthritis; Radiographic.

Figure 1. Hand radiographic features of KBD and the four criteria used for diagnosing adult KBD

Right hand of a 55 year old female KBD study participant with brachydactyly (A) and her right hand radiograph (B). The four hand radiographic features used for diagnosing adult KBD are marked with colored arrows: articular surface depression with sclerosis (yellow); “carpal crowding” (red); subchondral bone deformity in the proximal end of the phalanx (blue); and bony enlargement (between white arrows) with deformity of the distal end of phalanx (green).

Figure 2. Frequency of radiographic OA features of the joints of digit 1 (thumb) of the hand

The left panels represent the frequency of OST≥1 (A), JSN≥1 (B) and KL grade≥2 (C) in the three joints of digit 1 (thumb). The right panels represent the severely affected subgroups with OST=3 (D), JSN=3 (E) and KL grade=4 (F). IP, Interphalangeal joint; MCP, metacarpal-phalangeal joint; CMC, carpometacapal joint; All statistical analyses were adjusted for gender, age and body mass index (BMI). +, P value <0.05; ++, P value <0.01; +++, P value <0.001.

Figure 3. Frequency of radiographic features of the joints of digits 2–5 of the hand

The left panels represent the frequency of any OST≥1 (A), any JSN≥1 (B) and any KL grade≥ 2 (C) in three joint groups: DIPs, PIPs and MCPs of the four fingers (digits 2–5). The right panels represent the severely affected subgroups with any OST=3 (D), any JSN=3 (E) and any KL grade=4 (F). DIPs, distal interphalangeal joints; PIPs, proximal interphalangeal joints; MCPs, metacarpal-phalangeal joints. All statistical analyses were adjusted for gender, age and body mass index (BMI). +, P value <0.05; ++, P value <0.01; +++, P value <0.001.