Changes in the flexor digitorum profundus tendon geometry in the carpal tunnel due to force production and posture of metacarpophalangeal joint of the index finger: an MRI study

Idiopathic carpal tunnel syndrome and de Quervain's tenosynovitis: is there an association?

AIM

In this study, we aimed to investigate frequency of de Quervain's tenosynovitis (DQT) in patient with idiopathic carpal tunnel syndrome (ICTS).

MATERIAL AND METHODS

We evaluated 356 hands of 310 patients who applied with the pre-diagnosis of ICTS. Patients who have pain over the radial styloid, pain on movement, tenderness over the first dorsal extensor compartment and also positive Finkelstein's test were accepted clinically DQT. Presence of DQT was confirmed by ultrasonography. Motor and sensory conductions of median and ulnar nerves were studied in every hand with the pre-diagnosis of ICTS.

RESULTS

We determined ICTS in 302 (85%) hands. De Quarvain's tenosynovitis ratio was found to be 9.9% in hands with ICTS (n:302). In patients with ICTS and DQT in the same hand, the male-to-female ratio is 1/3. There were 29 cases (22 female, 7 male) with ICTS and DQT. Of the 30 hands with ICTS and DQT together; 18 had mild, nine had moderate, and 3 had severe ICTS.

CONCLUSION

This is the first study that evaluates the DQT and ICTS together. We found that patients with ICTS have a prevalence higher than normal population to have DQT. We suppose that considering DQT in patients with the pre-diagnosis of ICTS during clinical evaluation has a positive impact on clinical follow-up and treatment of these patients.

Effects of grip force on median nerve deformation at different wrist angles

The present study investigated the effects of grip on changes in the median nerve cross-sectional area (MNCSA) and median nerve diameter in the radial-ulnar direction (D1) and dorsal-palmar direction (D2) at three wrist angles. Twenty-nine healthy participants (19 men [mean age, 24.2 ± 1.6 years]; 10 women [mean age, 24.0 ± 1.6 years]) were recruited. The median nerve was examined at the proximal carpal tunnel region in three grip conditions, namely finger relaxation, unclenched fist, and clenched fist. Ultrasound examinations were performed in the neutral wrist position (0°), at 30°wrist flexion, and at 30°wrist extension for both wrists. The grip condition and wrist angle showed significant main effects (p < 0.01) on the changes in the MNCSA, D1, and D2. Furthermore, significant interactions (p < 0.01) were found between the grip condition and wrist angle for the MNCSA, D1, and D2. In the neutral wrist position (0°), significant reductions in the MNCSA, D1, and D2 were observed when finger relaxation changed to unclenched fist and clenched fist conditions. Clenched fist condition caused the highest deformations in the median nerve measurements (MNCSA, approximately -25%; D1, -13%; D2, -12%). The MNCSA was significantly lower at 30°wrist flexion and 30°wrist extension than in the neutral wrist position (0°) at unclenched fist and clenched fist conditions. Notably, clenched fist condition at 30°wrist flexion showed the highest reduction of the MNCSA (-29%). In addition, 30°wrist flexion resulted in a lower D1 at clenched fist condition. In contrast, 30°wrist extension resulted in a lower D2 at both unclenched fist and clenched fist conditions. Our results suggest that unclenched fist and clenched fist conditions cause reductions in the MNCSA, D1, and D2. More importantly, unclenched fist and clenched fist conditions at 30°wrist flexion and 30°wrist extension can lead to further deformation of the median nerve.

In vivo tissue interaction between the transverse carpal ligament and finger flexor tendons

The transverse carpal ligament (TCL) is a component of the flexor pulley system of the wrist, keeping the flexor tendons in place by resisting their volar displacement. The purpose of this study was to investigate the in vivo biomechanical interaction between the TCL and flexor tendons in response to tendon tensioning with the wrist at various postures. In eight healthy subjects, the flexor digitorum superficialis and profundus tendons were tensioned by isometrically applying loads (5, 10, and 15N) to the index finger while the wrist posture was at 20° extension, neutral, 20° flexion, and 40° flexion. The TCL and flexor tendons were imaged at the distal carpal tunnel cross section using ultrasound. The volar-dorsal positions of the tendons, TCL arch height, and TCL-tendon distances were calculated. With increasing wrist flexion, the flexor tendons moved volarly, the TCL arch height increased, and the TCL-tendon distances decreased, indicating that the flexor tendons contacted the TCL and pushed it volarly. The TCL-tendon interaction was amplified by the combination of finger loading and wrist flexion. This study provides in vivo evidence of the biomechanical interaction between the TCL and flexor tendons. Repetitive TCL-tendon interactions may implicate the interacting tissues and the median nerve resulting in tissue maladaptation and nerve compression.

Ultrasonographic median nerve changes under tendon gliding exercise in patients with carpal tunnel syndrome and healthy controls

STUDY DESIGN

Case control study.

PURPOSE OF THE STUDY

To evaluate the ultrasonographic median nerve changes under tendon gliding exercise in patients with carpal tunnel syndrome (CTS) and healthy controls.

METHODS

Seventy-three patients with CTS and 53 healthy volunteers were consecutively recruited. Each subject underwent a physical examination, nerve conduction studies and ultrasonographic examinations of the median nerve during tendon gliding exercises.

RESULTS

Significant changes in the cross-sectional area of the median nerve were found while moving from the straight position to the hook position and from the hook position to the fist position. There were also significant changes in the flattening ratio when moving from the hook position to the fist position.

CONCLUSIONS

Ultrasonography revealed that the median nerve was compressed in the fist position in both CTS patients and healthy volunteers. Thus, forceful grasping should be avoided during tendon gliding exercises performed in the fist position.

LEVEL OF EVIDENCE

3b.