Quantifying catch-and-release: the extensor tendon force needed to overcome the catching flexors in trigger fingers

Dorsal proximal interphalangeal joint tenderness is associated with prolonged postoperative pain after A1 pulley release for trigger fingers

BACKGROUND

In some trigger finger patients, tenderness is found in the dorsal proximal interphalangeal (PIP) joint. The etiology and prevalence of this condition are unclear. Furthermore, surgical outcomes for trigger fingers with coexisting dorsal PIP tenderness have not been reported. This study (1) determined the prevalence and risk factors for PIP joint tenderness in trigger fingers and (2) compared postoperative outcomes for trigger fingers with and without joint tenderness.

METHODS

This prospective cohort study was conducted between August 2018 and March 2020. We enrolled 190 patients diagnosed with single-digit trigger fingers undergoing open A1 pulley release. The incidence, demographic data, and surgical outcomes of patients with dorsal PIP tenderness were investigated. Factors associated with tenderness were analyzed, including patient occupation, finger involvement, trigger finger grading, duration of symptoms, previous corticosteroid injections, and presence of diabetes mellitus. A numeric pain scale, a patient-specific functional scale, and the range of motion were evaluated preoperatively and 1, 2, and 6 weeks after surgery, with telephone follow-ups at 3 and 6 months.

RESULTS

Of 190 patients, 46.8% had tenderness of the dorsal PIP joint. Patients with joint tenderness had significantly more overall postoperative pain for up to 6 weeks and reported residual minor pain for up to 3 months. The functional scale and range of motion of the 2 groups did not differ during follow-up. The only risk factor observed was the occupation of the patients.

CONCLUSION

Dorsal PIP tenderness is more common in trigger fingers than previously thought. It is also associated with higher and prolonged levels of postoperative pain after A1 pulley release. Therefore, patients with pre-existing PIP tenderness should be informed about the possibility of sustaining residual minor pain for up to 3 months after surgery.

LEVEL OF EVIDENCE

II.

A Finite Element Model for Trigger Finger

The aim of this study was to develop a finite element model to investigate the forces on tendons which ensue due to trigger finger. The model was used to simulate both flexor and extensor tendons within the index finger; two test cases were defined, simulating a “mildly” and “severely” affected tendon by applying constraints. The finger was simulated in three different directions: extension, abduction and hyper-extension. There was increased tension during hyper-extension, with tension in the mildly affected tendon increasing from 1.54 to 2.67 N. Furthermore, there was a consistent relationship between force and displacement, with a substantial change in the gradient of the force when the constraints of the condition were applied for all movements. The intention of this study is that the simulation framework is used to enable the in silico development of novel prosthetic devices to aid with treatment of trigger finger, given that, currently, the non-surgical first line of treatment is a splint.

Effectiveness of proximal interphalangeal joint-blocking orthosis vs metacarpophalangeal joint-blocking orthosis in trigger digit management: A randomized clinical trial

STUDY DESIGN

Patients with Green's classification grade 2 or 3 A1-pulley trigger digit (TD) were recruited and randomized to receive the proximal interphalangeal joint-blocking orthosis (PIPJ-BO) or metacarpophalangeal joint-blocking orthosis (MCPJ-BO).

INTRODUCTION

TD is a common hand condition that can affect one's performance in activities of daily living. Conservative management of TD involves prescription of orthoses to facilitate recovery. No studies have evaluated the effectiveness of PIPJ-BO, optimal orthosis wear regime, and other factors affecting orthotic effectiveness.

PURPOSE OF THE STUDY

To compare the effectiveness of PIPJ-BO vs MCPJ-BO in TD management.

METHODS

Outcome measures included pain numerical rating scale, Green's classification grading, and Quick Disability of the Arm, Shoulder and Hand. Orthosis wear duration was also collated. Patients were followed up for 2 months, and changes between initial and final assessment score within each group and between both groups were analyzed.

RESULTS

Thirty-five patients with 43 TD were included in final analysis. Twenty-three TD were allocated PIPJ-BO while 20 with MCPJ-BO. Pain reduction was observed in both groups, but reduction was greater in PIPJ-BO group (P = .02). About 47.83% in PIPJ-BO group and 40% in MCPJ-BO group improved by at least 1 Green's classification grade. There was only significant improvement in Quick Disability of the Arm, Shoulder and Hand score for PIPJ-BO group (P = .0007), and duration of orthosis wear was significantly longer in the PIPJ-BO group (P = .0010). Advancing age was found to have higher rate of orthosis failure.

DISCUSSION

Findings suggest that both orthoses are effective in reducing pain and disability and improve in triggering symptoms, with PIPJ-BO being more superior. Moreover, PIPJ-BO is less restrictive, has better cosmesis and allowed better functional performance than MCPJ-BO.

CONCLUSION

PIPJ-BO is more effective than MCPJ-BO in pain reduction and achieved better functional outcome. Orthosis wear of 24 hours for more than 8 weeks is recommended.

Comprehensive simulation on morphological and mechanical properties of trigger finger - A cadaveric model

Trigger finger has long been a common disorder in hand orthopedics. To clarify the unknown causative factors regarding the disease, numerous experiments were done on human cadavers, including tendon forces, tendon moment arm, mechanical properties of the pulley, gliding resistance, etc. However, most of these studies were conducted on normal fingers. As the etiology of trigger finger is still controversial on whether it is an outcome of tendon nodule or pulley scarring, in this study, a trigger finger model was built combining both the nodule created by silicone gel injection and pulley constriction by external compression. Indentation and gliding resistance tests were performed on cadaveric specimens to verify the model. Results showed that after silicone gel injection into the tendon, a significant increase in thickness was found. In addition, no significant difference was found in the toe region compressive modulus of the tendon after injection. Moreover, maximum, drop of gliding resistance and work of extension were all found to be significantly larger as the severity of triggering increased. Our results indicated we have developed a feasible cadaver model simulating trigger finger nodule which could be utilized for further experiments to elucidate other causative factors and biomechanical features of trigger finger in the future.

Trigger Finger: An Atraumatic Medical Phenomenon

Trigger finger is a mechanical problem with many etiological factors as possible causes, such as diabetes mellitus, carpal tunnel syndrome and repetitive finger movements. Although it can afflict anyone, it is much commoner in middle-aged women than men and the most commonly involved digit is reported to be the thumb. The diagnosis is mainly based on clinical symptoms during examination and first-line treatment is conservative with splinting and corticosteroid injections. Surgical open release is the “gold standard” of trigger finger treatment because it allows more careful inspection of the surgical area and is highly effective with low complication rates.

Finger movement function after ultrasound-guided percutaneous pulley release for trigger finger: effects of postoperative rehabilitation

OBJECTIVE

To develop and test a postoperative rehabilitation protocol for use by individuals with trigger finger undergoing ultrasound-guided percutaneous pulley release.

DESIGN

Nonrandomized controlled trial.

SETTING

Hospital and local community.

PARTICIPANTS

Individuals suffering from trigger finger with joint contracture (N=21) were recruited and grouped into an intervention group (n=9) or a control group (n=12).

INTERVENTIONS

All the participants underwent the same surgical procedure performed by the same surgeon. A 4-week postoperative rehabilitation program was designed based on the wound healing process. The intervention group received postoperative rehabilitation after the surgery, whereas the control group received no treatment after the surgery.

MAIN OUTCOME MEASURES

The finger movement functions were quantitatively evaluated before and 1 month after the surgery using a 3-dimensional motion capture system. The fingertip workspace and joint range of motion (ROM) were evaluated while the participant was performing a sequential 5-posture movement, including finger extension, intrinsic plus, straight fist, full fist, and hook fist.

RESULTS

The intervention group demonstrated significantly more improvements than the control group in the fingertip workspace (49% vs 17%), ROM of the distal interphalangeal (DIP) joint (16% vs 4%), ROM of the proximal interphalangeal (PIP) joint (21% vs 5%), and total active ROM (17% vs 5%).

CONCLUSIONS

This pilot study evaluated a postoperative rehabilitation protocol for trigger finger and demonstrated its effects on various finger functions. Participants who underwent the rehabilitation program had significantly more improvements in the fingertip workspace, ROM of the DIP and PIP joints, and total active ROM.

Carpal tunnel syndrome impairs thumb opposition and circumduction motion

BACKGROUND

Carpal tunnel syndrome is associated with sensory and motor impairments resulting from the compressed and malfunctioning median nerve. The thumb is critical to hand function, yet the pathokinematics of the thumb associated with carpal tunnel syndrome are not well understood.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate thumb motion abnormalities associated with carpal tunnel syndrome. We hypothesized that the ranges of translational and angular motion of the thumb would be reduced as a result of carpal tunnel syndrome.

METHODS

Eleven patients with carpal tunnel syndrome and 11 healthy control subjects voluntarily participated in this study. Translational and angular kinematics of the thumb were obtained using marker-based video motion analysis during thumb opposition and circumduction movements.

RESULTS

Motion deficits were observed for patients with carpal tunnel syndrome even though maximum pinch strength was similar. The path length, normalized by palm width of the thumb tip for the patients with carpal tunnel syndrome was less than for control participants (opposition: 2.2 palm width [95% CI, 1.8-2.6 palm width] versus 3.1 palm width [95% CI, 2.8-3.4 palm width], p < 0.001; circumduction: 2.2 palm width [95% CI, 1.9-2.5 palm width] versus 2.9 palm width [95% CI, 2.7-3.2 palm width], p < 0.001). Specifically, patients with carpal tunnel syndrome had a deficit of 0.3 palm width (95% CI, 0.04-0.52 palm width; p = 0.022) in the maximum position of their thumb tip ulnarly across the palm during opposition relative to control participants. The angular ROM also was reduced for the patients with carpal tunnel syndrome compared with the control participants in extension/flexion for the metacarpophalangeal (opposition: 34° versus 58°, p = .004; circumduction: 33° versus 58°, p < 0.001) and interphalangeal (opposition: 37° versus 62°, p = .028; circumduction: 41° versus 63°, p = .025) joints.

CONCLUSIONS

Carpal tunnel syndrome disrupts kinematics of the thumb during opposition and circumduction despite normal pinch strength.

CLINICAL RELEVANCE

Improving understanding of thumb pathokinematics associated with carpal tunnel syndrome may help clarify hand function impairment associated with the syndrome given the critical role of the thumb in dexterous manipulation.

One digit interruption: the altered force patterns during functionally cylindrical grasping tasks in patients with trigger digits

Most trigger digit (TD) patients complain that they have problems using their hand in daily or occupational tasks due to single or multiple digits being affected. Unfortunately, clinicians do not know much about how this disease affects the subtle force coordination among digits during manipulation. Thus, this study examined the differences in force patterns during cylindrical grasp between TD and healthy subjects. Forty-two TD patients with single digit involvement were included and sorted into four groups based on the involved digits, including thumb, index, middle and ring fingers. Twelve healthy subjects volunteered as healthy controls. Two testing tasks, holding and drinking, were performed by natural grasping with minimal forces. The relations between the force of the thumb and each finger were examined by Pearson correlation coefficients. The force amount and contribution of each digit were compared between healthy controls and each TD group by the independent t test. The results showed all TD groups demonstrated altered correlation patterns of the thumb relative to each finger. Larger forces and higher contributions of the index finger were found during holding by patients with index finger involved, and also during drinking by patients with affected thumb and with affected middle finger. Although no triggering symptom occurred during grasping, the patients showed altered force patterns which may be related to the role of the affected digit in natural grasping function. In conclusion, even if only one digit was affected, the subtle force coordination of all the digits was altered during simple tasks among the TD patients. This study provides the information for the future studies to further comprehend the possible injuries secondary to the altered finger coordination and also to adopt suitable treatment strategies.