A Retrospective Study of Two Measures of Functional Outcome for Metacarpophalangeal Joint Replacement in Patients with Rheumatoid Arthritis

Abstract

With the aim of determining the relative merits of two functional assessments used to measure outcome for metacarpophalangeal joint arthroplasty and their relationship to range of motion a retrospective study was carried out on patients with rheumatoid arthritis who underwent Swanson Silastic® metacarpophalangeal joint replacement between 1986 and 1997. Records of pre-operative and post-operative functional tests were completed for 30 hands in 27 patients (64 joint replacements) and range of motion measurements on 29 hands in 26 patients (60 joint replacements). Two functional tests had been used: the Upper Extremity Function Test (33 sub-tests) for 19 hands (Group A) and the Hand Grip Test (20 sub-tests) for 11 hands (Group B). The pre-operative timing of assessments was on average 4.1 months for Group A and six months for Group B and the post-operative timing 4.1 months and 4.3 months respectively. The functional tests demonstrated an average change of 22% (CI 15.8 to 28.3) in Group A and 7.5% (CI −1.1 to 16.1) in Group B. Range of motion was calculated as Total Active Motion for all fingers and demonstrated in Group A an average change for index of 11.5° (CI −6.5 to 29.5), middle 27.3° (CI 3.3 to 51.3), ring 23.3° (CI 1.1 to 45.5) and little finger 31.7° (CI 2.8 to 59.7). Total Active Motion in Group B averaged a change for index of 12° (CI −4.0 to 28.0), middle 18.5° (CI −8.1 to 45.2), ring 9.5° (CI −13.1 to 32.0) and little finger 17.7° (CI −8.3 to 43.8). Overall a greater improvement was demonstrated with the Upper Extremity Function Test while Total Active Motion did not always show improvement. The more severe pre-operatively deformed hands showed most improvement. For those with less severely deformed hands, the Hand Grip Test may not be sensitive enough to detect functional difficulties.