One year after surgery for TMJ joint osteoarthritis, most patients had experienced a major reduction of pain at rest from a mean score of 50 to 12 and the mean QuickDASH score was reduced by more than half. However, patients should be informed that a complete resolution of pain on load and weakness not is to be expected 1 year after surgery (mean score 30 and 34, respectively). Younger patients and women reported slightly worse PROM both before and after surgery but the mean individual improvement in PROM did not differ between age groups or gender.
Our data may be used for preoperative patient information about the expected outcome after surgery. Further, the presented data can be useful as reference values for power calculations in the design of studies comparing interventions for TMJ joint osteoarthritis and also applied as benchmark values to which the results of observational studies can be compared.
The registry data confirmed that trapeziectomy and LRTI still is the prevailing surgical method in Sweden despite reports that LRTI has shown no advantage over simple trapeziectomy but rather a higher risk for complications [2, 4, 14]. Reports from the United States [6, 15] demonstrate the same tendency that clinical practice does not follow available evidence. The mean PROM values for all patients favored simple trapeziectomy at 3 months postoperatively regarding stiffness, ADL and QuickDASH but the differences were probably too small to be relevant. Results were similar 1 year postoperatively which is in line with former studies [2, 4, 14]. We could not make a well-founded comparison of the individual improvement after simple trapeziectomy versus LTRI due to low response rates and the fact that so few of the former method was performed. Thus, we cannot make any recommendations regarding surgical method based on this study. It was not possible to distinguish different type of LRTI in the data so LRTI:s were by necessity grouped as one category which might not be optimal. However, there is no solid evidence that results differ after various LRTI [3].
The strong point of this study is the large sample. This is valuable in analysis of subjective variables such as PROM that inherently have a large individual variance and might be affected by other factors such as depression or other upper-extremity comorbidities [16, 17]. To reduce the uncertainty due to individual variance, we made paired analyses of the individual improvement in PROM. Due to low response rates and the fact that many patients did not respond at all three occasions, the samples were markedly reduced in the paired analyses and this affected in particular the comparison between surgical methods.
A problem with the large sample is that small differences in PROM that might not be clinically important, may reach statistical significance. The minimum clinically important difference (MCID) for QuickDASH was determined by Franchignoni et al. [18] to16 points. MCID for HQ-8 items have not yet been described. In general, MCID tend to be 0,5 SD [19]. We found (statistically) significantly worse PROM scores in younger patients and in women both before and after surgery, but none of the differences in the HQ-8 item scores were close to 0,5 SD. QuickDASH was significantly higher in women at all times but the difference was 10 points at most. The differences could be attributable to higher functional demands in younger patients and differing ADL and life-style habits, anatomical variability or pain perception between men and women but the differences may as well represent normal variation. Since the effect of the operation (i.e. improvement of PROM) did not differ between age groups or gender, we do not interpret our results as younger patients and female having an inferior result after operation.
Registry studies enable inclusion of many more patients than randomized controlled trials (RCTs), which often compare relatively few patients treated under strictly controlled conditions. Moreover, registry studies report the “real life” situation, including all types of patients, treated at different centers and operated by many different surgeons. For many hand conditions, RCTs is almost impossible to perform due to small populations and we believe that registry studies will be increasingly important in the field of hand surgery. On the other hand, potential confounders cannot not be controlled for in registry studies which might induce e.g. selection bias regarding surgical method.
A limitation of this study is that the sample did not include re-operated patients and we have no information on complication rates. Patients who sustained postoperative complications probably would have affected the patient reported outcomes negatively. Further, 1 year is a relatively short follow-up time and the result may change with time. Yeoman et al. [20] report a mean quick-DASH of 40 after 3,5–17 years after simple trapeziectomy which is considerably higher than in this sample (QuickDASH 26). The poor response rate is a major limitation of the HAKIR and thus of this study. The HQ-8 questionnaire is presently issued mainly by e-mail, as a web-survey. There is a risk that e-mails end up in spam filters or that patients are not motivated to respond. One reminder to answer the questionnaire is send by a sms. There is a risk that the older population answers web-surveys to a lesser extent. However, the mean age of the non-responders was actually lower than responders. For all ages, there is a risk for survey fatigue so simple questionnaires with few questions are probably favorable for a better response rate and we believe that the HQ-8 fulfill this request. More information to patients about the registry and its purpose could be an incentive. Improved response rate is a crucial improvement needed for the HAKIR to reach its full potential to compare hand surgical interventions.