Abstract
Background The general assessment of basal joint arthritis (BJA) is limited using the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. This has been shown to be insensitive to pain and disability levels, leading to the development and validation of the thumb disability examination (TDX) as a specific tool for BJA in 2014.
Objective The goal of this study was to evaluate the reliability, sensitivity, and specificity of the TDX score for BJA.
Methods A multicenter BJA database was established in 2007 to collect prospective data. We evaluated the correlation between the TDX score, visual analog pain scale with activity (A-VAS), Eaton–Littler score, and grip strength using a Pearson test. Additionally, we evaluated the pre- and postintervention scores to assess their predictive values.
Results A total of 109 thumbs of 74 patients with TDX scores were evaluated. Females were more commonly affected (75.2%), and the mean age was 65.39 years (standard deviation: 10.04). The majority of participants were white (90.8%). A high correlation between TDX and A-VAS score (Pearson's correlation = 0.520; p < 0.001) and between grip strength (Pearson's correlation = –0.336; p < 0.005) and Eaton–Littler score (Pearson's correlation = 0.353' p < 0.01) was identified. Additionally, when comparing pre- and post-intervention for all treatment groups and for operative intervention, significant differences in TDX scores were observed (both p ≤ 0.01). No significant differences could be identified for DASH score or A-VAS when assessing these same groups.
Conclusion The TDX score correlates to high Pearson's correlation values and p -values, especially in grip strength, Eaton–Littler score, A-VAS score, and pre-/postintervention for all treatment groups combined and when specifically assessing the surgical intervention group. As a result, it can be concluded that the TDX score is a specific tool for the assessment of BJA.
Level of Evidence This is a Level II, prospective comparative study.
Keywords: functional outcome, basal joint, arthritis, thumb, outcome
The basal joint of the thumb is a complex joint that allows movements in three different planes and is the most common site of osteoarthritis in the hand. The thumb accounts for approximately 50% of the overall function in the hand, which, when compromised, may lead to severe limitations and disabilities in daily activities. 1 Risk factors for arthritis include age, gender, ethnicity, trauma, repetitive use, genetic factors, obesity, history of inflammatory joint disease, and metabolic, congenital, and developmental defects. 2 When looking at the upper extremity, basal joint arthritis (BJA) is the most common arthritic condition, and severe cases can require surgical intervention. 3 4 There is increasing incidence with age, and approximately 33% of postmenopausal women are affected by BJA. 5
Diagnostics for the severity of BJA are based on the identification of the limitations in daily activities by assessing functional outcome and radiographic scores, as well as patient-reported outcome measures. Several different outcome measures exist, such as the Michigan Hand Questionnaire, Australian/Canadian Hand Osteoarthritis Index, Patient-Rated Wrist Evaluation, 6 and the Disabilities of the Arm, Shoulder, and Hand (DASH), visual analog pain scale (VAS) with activity (A-VAS), as well as radiographic scores such as the Eaton–Littler score, the modified Eaton–Glickel score, Kellgren–Lawrence classification, and the thumb osteoarthritis (ThOA) index. 7 The most common and widely accepted scores are the DASH score (current gold standard), A-VAS, and Eaton–Littler score, which are assessed in daily practice. These outcome questionnaires (DASH, VAS) and radiographic scores (Eaton–Littler) have been used to compare various surgical techniques and determine the individual success of treatment.
The pain VAS is one of the easiest outcomes to obtain and has been widely reported in upper extremity literature. 8 The DASH questionnaire has been validated; however, it may not be sufficiently specific for basal joint disabilities. 9 This is due to the fact that the DASH can account for encounters different pathophysiological conditions or injuries of the upper extremities, such as elbow fractures or arthritis, carpal tunnel syndrome, shoulder stiffness, and tendinopathies. Furthermore, there has been no reported correlation between the Eaton–Littler score and the QuickDASH score in the literature. 6 10 11 Therefore, the indication for treatment relies heavily on hand surgeon experience.
In 2014, a new functional outcome score was developed and validated, called the thumb disability examination (TDX), which contains 20 thumb specific questions on daily activities. The TDX score and associated validation procedures were subsequently published in 2017. 12 Based on the validation of the questionnaire in 65 patients, it was reported to be a quick, easy, and reliable tool that could be assessed in approximately 2 minutes and correlated strongly with grip strength ( p < 0.01), A-VAS ( p < 0.01), and DASH score ( p < 0.001). 12
The primary purpose of this study was to further evaluate whether the TDX is a reliable, sensitive, and disease-specific tool for BJA. The secondary purposes of this study were to report on the demographics of the patients in the database and to compare the TDX with the A-VAS, range of motion (ROM), grip strength, and Eaton–Littler score.
Methods
A multicenter BJA registry was launched in 2007 and includes four study sites. It is an observational, prospective database that includes any patient with symptomatic BJA who presents to one of the locations. All patients who are under 18 years of age, suffer from neuromuscular diseases affecting the hand, have known inflammatory conditions, do not speak English fluently, have a history of or current basal joint infection, or have severe dementia are excluded. The database includes demographic data (i.e., age, race, dominant hand, education level), the DASH score, pain VAS score, ROM, grip strength, key pinch, tip pinch, Eaton–Littler score, and type of treatment performed. Since the development of the TDX score in November 2013, this questionnaire has been included in the database as well.
For evaluation, all patients were asked to fill out three questionnaires including the TDX, DASH, and a demographic questionnaire. The demographic questionnaire assessed hand dominance, previous treatments, onset of symptoms, comorbidities, family history of arthritis, and VAS at rest and with activity. In patients with bilateral BJA, the TDX was assessed for each side. A physical examination was performed by a trained research assistant to assess objective clinical measurements including ROM (ROM) of the trapeziometacarpal, metacarpophalangeal (MCP), and interphalangeal joints using a goniometer. Grip, key pinch, and tip pinch strength were also assessed using a dynamometer. The Eaton–Littler score was graded by the treating orthopedic surgeon. Finally, all data points were entered into the basal joint registry.
Patient data that did not meet follow-up criteria due to death, loss to follow-up, change in treatment, or repeat intra-articular steroid injection within a 6-month timeframe (study period) of the index procedure (hereby defined as first treatment of their BJA) were not included in the analysis. Since the patients' compliance with conservative treatment (splinting) is difficult to assess, we only evaluated injection therapy and surgery for follow-up.
We have received continued approval from our Institutional Review Board.
Since 2007, 405 patients were included in the BJA registry, and since the development of the TDX score, 109 questionnaires, as well as DASH score and A-VAS were completed. Furthermore, standard-of-care radiographs were obtained, and a conventional radiographic analysis was performed prior to surgical intervention to assess the severity of BJA and record the Eaton–Littler score.
Patients were followed-up at a mean of 281.4 days after enrollment in the study, and initiation of treatment ranged from 12 to 887 days. This varied among the treatment indicated. Of the patients, 41 underwent surgery, with a mean follow-up of 352.2 days (range: 40–887 days), and 37 underwent injection therapy, with a mean follow-up of 209.1 days (range: 19–399 days). In the remaining 31 patients, conservative treatment with splinting was initiated. In all patients, conservative treatment was initiated even prior presentation during office hours. Therefore, the mean follow up was 60 days (range: 12–165 days).
For surgical procedure, a combination of metacarpal osteotomy, dorsal ligament tightening, trapeziometacarpal arthrodesis, MCP capsulodesis, carpometacarpal (CMC) arthroscopy, and ligament reconstruction was performed in all patients. In one case, a tendon interposition was performed according to our database.
Statistical testing for significance ( p < 0.05) was performed using the analysis of variance test or paired t -test for continuous variables, and chi-square test for categorical variables using the Origin software (OriginLab Corp., Northampton, MA) and SPSS (IBM Corp., Armonk, NY). The between-group comparisons were conducted using Pearson's correlation.
Results
In total, 405 patients were enrolled in the registry; 296 patients were excluded as no TDX score was assessed.
Women were more commonly affected (82 cases [75.2%]) at a mean age of 65.4 years; 37 to 86. 90.8% of the participants were white followed by black or African-American (3.7%), Asian (3.7%), and the remaining unknown (1.8%). In 66 cases, the right side was affected, and in 78 patients, the left side was affected; 35 patients suffered bilaterally.
The mean TDX score was 55.80 ± 19.03, and the DASH score 36.53 ± 22.18. When performing a Pearson test, we identified a significant correlation between the TDX score and the A-VAS ( p < 0.005), Eaton–Littler score ( p < 0.05), and grip strength ( p < 0.005). No correlation was identified between TDX, and key pinch and tip pinch. For the DASH score, a significant correlation was identified as well with a Pearson correlation of 0.448 ( p < 0.001) ( Table 1 ).
Table 1. Correlations of the TDX score.
| Mean | TDX | DASH | |
|---|---|---|---|
| Grip strength ( N ) | 29.64 (±22.01) | −0.336 ( p < 0.005) | 0.016 ( p = 0.891) |
| Key pinch ( N ) | 8.42 (±9.99) | −0.089 ( p = 0.453) | 0.167 ( p = 0.160) |
| Tip pinch ( N ) | 6.21 (±9.69) | −0.054 ( p = 0.650) | 0.181 ( p = 0.125) |
| VAS | 5.47 (±2.74) | 0.520 ( p < 0.005) | 0.169 ( p = 0.205) |
| Eaton–Littler score | 2.49 (±0.91) | 0.353 ( p = 0.007) | 0.387 ( p < 0.005) |
| DASH score | 36.53 (±22.18) | 0.448 ( p < 0.001) |
Abbreviations: DASH, Disabilities of the Arm, Shoulder, and Hand; VAS, visual analog scale; TDX, thumb disability examination.
Note: Significances are presented in bold.
For ROM, only one significant correlation was identified for MCP flexion, with p = 0.044 for TDX and p = 0.015 for DASH. Other than that, no further correlations were found ( Table 2 ).
Table 2. Correlations of the range of motion.
| Mean | TDX | DASH | |
|---|---|---|---|
| IP flexion | 53.45 degrees (±17.64) | −0.054 ( p = 0.644) | 0.019 ( p = 0.874) |
| IP extension | 4.39 degrees (±28.40) | 0.137 ( p = 0.245) | 0.150 ( p = 0.203) |
| MCP flexion | 42.41 degrees (±24.14) | 0.237 ( p = 0.044) | 0.284 ( p = 0.015) |
| MCP extension | 15.63 degrees (±33.73) | 0.091 ( p = 0.448) | 0.103 ( p = 0.391) |
| Radial abduction (cm) | 4.70 (±1.10) | −0.226 ( p = 0.230) | 0.006 ( p = 0.975) |
| Palmar abduction (cm) | 4.47 (±1.36) | −0.177 ( p = 0.350) | 0.045 ( p = 0.813) |
| Opposition (Kapandji) | 8.47 (±0.97) | −0.174 ( p = 0.357) | −0.077 ( p = 0.687) |
Abbreviations: DASH, Disabilities of the Arm, Shoulder, and Hand; IP, interphalangeal; MCP, metacarpophalangeal; TDX, thumb disability examination.
Note: values of radial and palmar abduction were measured as the distance from the IP crease to the transverse palmar crease. Significances are presented in bold.
The Eaton–Littler score shows a correlation with the TDX as well as the DASH score. Slightly higher significances were noted for the DASH score, which is why we investigated the individual grades of the Eaton–Littler score. No significances between each group could be identified here, as shown in Fig. 1 (1). There was an upward trend observed for the TDX and DASH score related to the individual grades but not for the VAS score.
Fig. 1.
DASH, VAS, and TDX score classified by the Eaton–Littler score without any significances. DASH, Disabilities of the Arm, Shoulder, and Hand; VAS, visual analog scale; TDX, thumb disability examination. (Colored version of the figure is available online only).
For those patients who underwent injection therapy or surgery, our data clearly demonstrate that the TDX score can be used as a significant predictor of the treatment success overall for all treatments ( p < 0.01) as well as when specifically looking at surgical procedure ( p < 0.05), whereas neither the DASH score nor the A-VAS showed significant differences pre- and posttreatment ( Table 3 ).
Table 3. Before and after each individual intervention.
| Timing | Overall | Surgery | Injection | |
|---|---|---|---|---|
| N | 109 | 41 | 37 | |
| TDX | Pre | 61.5 (±3.2) | 61.3 (±4.6) | 58.4 (±3.2) |
| Post | 46.8 (±3.9) ( p = 0.006) | 42.2 (5.1) ( p = 0.010) | 51.5 (±5.9) ( p = 0.320) | |
| DASH | Pre | 40.4 (±4.8) | 41.2 (±6.5) | 33.4 (±5.0) |
| Post | 31.3 (±4.3) ( p = 0.161) | 29.9 (±5.4) ( p = 0.188) | 27.7 (±5.0) ( p = 0.432) | |
| VAS | Pre | 6.2 (±0.8) | 5.5 (±1.3) | 7.0 (±0.4) |
| Post | 3.9 (±0.9) ( p = 0.076) | 3.3 (±0.9) ( p = 0.180) | 3.8 (±2.0) ( p = 0.167) |
Abbreviations: DASH, Disabilities of the Arm, Shoulder, and Hand; VAS, visual analog scale; TDX, thumb disability examination.
Note: standard errors of the mean are given in brackets; significances are indicated before and after treatment in bold.
Discussion
BJA is one of the most common forms of arthritis, which may cause major disability in daily activities. As insurance and patient care are becoming more quality and cost-effectiveness oriented, 9 13 14 it is important to qualify the functional outcome based on a questionnaire before and after each individual treatment procedure to predict treatment success, patient satisfaction, and cost-effectiveness.
In our study, the age of clinical presence was 65.4 years (standard deviation: 10.0), which is in concurrence with the literature reporting that women are more affected than men (75.2%). 4 Interestingly, our database shows that white people were more affected in our cohort with even higher percentages than mentioned in the literature (90.8 vs. 50.0%). 15 16 Jordan described that African-Americans are less affected by hand osteoarthritis but suffered more from multiple large joints. In Caucasians, hand osteoarthritis phenotypes were observed more often but with various phenotypes that coexisted with hip or knee osteoarthritis. 17 In our cohort, the findings may be related to the selection bias and the location of the centers where the study was performed, as well as a rather small sample size.
For the assessment of the severity of BJA, the current gold standard outcome measure is the DASH score, which our results report to be not very specific when looking at BJA.
When the TDX was first validated, Noback et al reported an average completion time of 134 seconds, whereas it took approximately 7 minutes to complete the DASH score. 12 18 The TDX therefore lends itself to greater compliance as patients and physicians are more willing to complete a questionnaire fully that is brief and specific for BJA. Grip strength has shown higher significant correlation with CMC joint osteoarthritis ( p < 0.001) compared with pinch strength ( p = 0.049) in the literature. The pinch strength showed a stronger correlation to metacarpal joints. Similar findings are suspected for the key pinch. 19 Furthermore, Spacek et al concluded that grip strength deficits are more important in hand disability with BJA than in patients with interphalangeal osteoarthritis. 20
For the TDX score, a significant correlation with the VAS score, DASH score, grip strength, MCP flexion, and Eaton–Littler score was identified. Furthermore, a significant correlation between both the TDX and DASH with the Eaton–Littler score, with the DASH having slightly higher values than the TDX score ( Fig. 1 ). However, no correlation between the QuickDASH and Eaton–Littler scores has been described in the literature. 11 In comparison to the Eaton–Littler score, the ThOA index and the Eaton–Glickel score showed slightly higher reproducibility, with higher intraclass correlation coefficients (Eaton–Littler score of 0.73 vs. ThOA index of 0.95 vs. Eaton–Glickel score of 0.83); however, they are not as widely accepted and may require a special radiographic view. The Roberts view (ThOA), which is not routinely performed, could address some of the gaps in the previous scores. 21 Furthermore, no significant correlation of Eaton–Littler score could be identified with grip strength, key pinch, tip pinch, or VAS score, which also serves to remind us about the relevance of radiographic scores, mainly that they do not consistently represent the clinical relevance of this disease.
For the prediction of the individual procedure, no significance was observed in DASH and VAS scores; however, the TDX score showed reliable, significant changes between pre- and postintervention overall and for surgical intervention (both p ≤ 0.01). For injection and splinting, the population was underpowered and the follow-up period was much shorter; however, a positive trend was identified. In nearly all patients, the conservative treatment with splinting was already initiated prior to their first presentation in our centers. Therefore, the follow-up was rather short based on patient selection. The comparison of the DASH and TDX scores may be still valid in this cohort, as they show lower p -values for the TDX score than the DASH score.
Conclusion
BJA is a common cause of thumb pain, resulting in severe disabilities in daily activities. For patients, insurers, and physicians, it is important to employ a reliable and useful tool to assess and objectify the daily limitations of BJA. The TDX is a fast, reliable, reproducible, and specific tool that can be used to predict the functional outcome and therefore define clinical excellence in the treatment of BJA.
Funding Statement
Funding This work was funded in part by a grant by the Orthopedic Science and Research Foundation.
Conflict of Interest None declared.
Ethical Approval
The ethical review committee of the associated hospitals approved the study.
International Review Board approval was obtained.
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