The literature suggests patients with an intracompartmental septum in the first extensor compartment are more likely to have de Quervain’s disease develop and to be resistant to nonoperative management. These arguments are based on observations that the septum is more prevalent in patients than in cadavers. However, these observations do not allow evidence-based conclusions because no direct comparisons were made between patents with de Quervain’s disease and the healthy population regarding the prevalence of the septum or between patients with and without a septum concerning nonoperative treatment outcomes. The actual prevalence of the intracompartmental septum in patients with de Quervain’s disease has not been determined, as there was no noninvasive means of determining the presence of a septum in patients who were responsive to nonoperative treatment. In the current study, we explored the use of sonography to identify the presence of an intracompartmental septum in patients with de Quervain’s disease by evaluating its accuracy using surgical findings as the gold standard.
We acknowledge several limitations. The first is that sonography does not visualize the intracompartmental septum directly. Accordingly, other lesions likely to be seen as a hypoechoic lesion between the tendons, such as intratendinous degeneration, fluid collection, or synovial proliferation, should be carefully differentiated. Longitudinal tracing, or anisotropy of a lesion, which signifies changing appearance of a lesion with changing direction of examination and is considered a characteristic of a tendon, and provocative maneuvers would be helpful for differential diagnosis. Second, our findings should be applied with caution to patients without symptoms or with mild symptoms. It is possible the intracompartmental septum in those groups is difficult to distinguish from the adjacent tendons. However, we believe sonography can identify the septum in most patients with de Quervain’s disease because sonography was able to show septum-like structures in asymptomatic wrists in this study.
Our observations suggest sonography accurately identifies the intracompartmental septum in the first extensor compartment in patients with de Quervain’s disease who were unresponsive to nonoperative treatment. This finding concurs with that of Nagaoka et al. [14
]. In their retrospective study, sonography positively identified the septum in 26 of 27 wrists with a surgically proven septum (sensitivity, 96%) and negatively identified the septum in five of five wrists without the septum. They failed to identify a septum in one wrist, in which the septum was thin and incomplete. In contrast, we did not encounter a septum that was too thin or incomplete to be detected by sonography, which we attribute to the use of a more accurate transducer. Furthermore, caution should be exercised when interpreting hypoechoic lesions between the tendons in the radial styloid area. One wrist was deemed to have a septum by sonography, but no septum was found during surgery. On reviewing the sonographic images in this case, we observed small, dotlike structures in the hypoechoic area, which are believed to have represented tendon fibers. Furthermore, the hypoechoic area was contained in tendons (Fig. ). We speculate the observed hypoechoic area represented a degenerated area in the tendon. Additional longitudinal scan or provocative maneuvers to assess tendon gliding along a fixed septation or to assess lateral displacement of the tendons by the pressure of the transducer over the first dorsal compartment may have more accurately localized this lesion in a specific tendon, being able to distinguish it from a septum. In addition, a hypoechoic area between the tendons does not necessarily indicate the presence of a septum because it could be a space between the tendons if the transducer is placed distal to the first extensor compartment. Thus, to ensure sonographic examinations are performed on the first extensor compartment, it is important to note the hyperechogenicity of the bone of the distal radius just below the tendons.
Our study also showed a septum-like structure between the tendons in the first extensor compartment could be observed in the asymptomatic wrists by sonographic examination. We observed this structure in 71% of asymptomatic contralateral wrists of the patients with the septum and in 15% of those without the septum. The bilaterality of the septum based on sonographic examination was similar to results in a previous anatomic study using cadavers [6
], which suggested sonography may detect the septum in the asymptomatic individuals. However, the accuracy of sonographic examination in this population has not been determined because no gold standard measure such as surgery could be used for comparison.
The presence of an intracompartmental septum generally is believed to be associated with the development of de Quervain’s disease. Investigations of cadaveric wrists have revealed the presence of an intracompartmental septum in the first extensor compartment in 47% (range, 20%–78%) of wrists on average, and this prevalence is greater (average, 59%; range, 44%–91%) in the wrists of patients with de Quervain’s disease [3
]. When we combined data from previous studies to calculate the relative risk conferred by an intracompartmental septum to the development of de Quervain’s disease, we found a relative risk of 1.40 (95% CI, 1.19–1.65) (Tables , ). Therefore, it seems plausible the presence of an intracompartmental septum is a risk factor for de Quervain’s disease development. However, this calculated relative risk is likely to be affected by selection bias. The patients included in the above studies likely had an intracompartmental septum because treatment with local steroids or other nonoperative measures had failed, and the intracompartmental septum might have been a major reason why these measures failed [5
]. To validate the association between the intracompartmental septum and the occurrence of de Quervain’s disease, data for patients, not yet reported, who were treated successfully with local steroid injection or other nonoperative measures should be included. Sonography will be useful for identifying the septum in these patients without surgical exploration.
Summary of previous investigations
Calculation of relative risk and 95% confidence interval
Similar bias could be found in the studies that suggested an association between the presence of the septum and the poor outcome after local steroid injection in de Quervain’s disease. Witt et al. [19
] indicated the intracompartmental septum could be a possible cause of steroid injection failure in patients with de Quervain’s disease, based on the observation that 22 of 30 patients (73%) unresponsive to steroid injections had an intracompartmental septum, which was greater than numbers reported in cadaveric studies. Other authors shared this view, reporting a higher prevalence of the intracompartmental septum in patients who experienced steroid treatment failure [5
]. However, these studies inadequately support the association between the presence of an intracompartmental septum and steroid treatment failure because responders to nonoperative treatment were not used as control subjects. This type of comparative study has been difficult to conduct for ethical reasons as the information for those who responded to nonoperative treatment could be obtained only by surgical exploration. We believe sonography provides an effective diagnostic tool for this purpose.
An accurate injection of steroid into both compartments reportedly improves the outcomes in patients with de Quervain’s disease. Zingas et al. [22
] reported a higher rate of symptom relief was attained in patients with successful steroid injections into the APL and EPB compartments than that with a steroid injection only into the APL or none of the compartments. Exact delivery of steroids into both compartments under the guidance of sonography may lead to improved outcomes.
Sonography is useful to identify the intracompartmental septum in the first extensor compartment in patients with de Quervain’s disease. Sonographic examinations may be used to verify whether the intracompartmental septum is a risk factor for steroid injection failure and disease development and to accurately deliver steroids into both compartments in patients with de Quervain’s disease.