Histology of the volar plate of the thumb metacarpophalangeal joint

BACKGROUND

The aim of the study was to describe the histology of the thumb MCPJ volar plate.

METHODS

Five fresh-frozen thumbs were dissected. The volar plates were harvested from the thumb MCPJ. Histological analyses were performed using 0.04% Toluidine blue and counterstained with 0.005% Fast green.

RESULTS

The thumb MCPJ volar plate comprised two sesamoids, dense fibrous tissue and loose connective tissue. The two sesamoids were connected by dense fibrous tissue, with collagen fibers oriented transversely (perpendicular to the long axis of the thumb). In contrast, the collagen fibers within the dense fibrous tissue on the lateral sides of the sesamoid were oriented longitudinally in line with long axis of the thumb. These fibers blended with the fibers of the radial and ulnar collateral ligaments. The collagen fibers in the dense fibrous tissue distal to the sesamoids ran transversely, perpendicular to the long axis of the thumb. The proximal aspect of the volar plate showed only loose connective tissue. The volar plate of the thumb MCPJ was largely uniform with no division of layers from the dorsum to the palmar surface. There was no fibrocartilaginous component in the thumb MCPJ volar plate.

CONCLUSIONS

The histology of the volar plate of the thumb MCPJ differs significantly from the conventional understanding of the volar plate, based on the volar plate of finger proximal interphalangeal joints. The difference is likely due to the presence of the sesamoids, which confer additional stability, reducing the need for a specialized trilaminar fibrocartilaginous structure with the lateral check-rein ligaments found in the volar plate of finger proximal interphalangeal joints to confer additional stability.

Arthroscopic Thermal Shrinkage: A Novel Method for the Treatment of Chronic Volar Plate Instability at the Metacarpal Phalangeal Joint of the Thumb

Background: Chronic volar plate instability of the thumb metacarpal phalangeal joint (MCPJ) is a disabling clinical problem. Patients usually present with pain and disability in terms of reduction in pinch and grip power. Numerous surgical techniques have been described for the treatment of this condition. Here we describe a novel method for the treatment of this condition by thermal shrinkage of the volar plate via thumb MCPJ arthroscopy. Methods: A retrospective review of 8 patients with chronic thumb MCPJ volar plate instability treated with the novel technique of thermal shrinkage of the volar plate via thumb MCPJ arthroscopy. The primary outcome is maintenance of saggital plane stability at the thumb MCPJ. Secondary outcomes include pinch and grip power, The Disabilities of the Arm, Shoulder and Hand (DASH) Score and thumb MCPJ range of movement. The duration of follow up and complications were also reviewed. Results: The mean follow up period was 41.4 months (range, 2-134 months). One case had recurrence of instability requiring open volar plate capsulodesis. All other cases had their thumb hyperextensibility resolved and maintained throughout the entire follow up period, up to 134 months for the case with the longest duration of follow up. Conclusions: Preliminary results suggest this novel, minimally invasive technique for the treatment of thumb MCPJ volar plate instability is effective and the long term follow up results are durable.

Reliability and Validity of the Japanese Version of the Michigan Hand Outcomes Questionnaire: A Comparison with the DASH and SF-36 Questionnaires

Background: The Michigan Hand Outcomes Questionnaire (MHQ) has shown reliability, validity and responsiveness and has been used to assess surgical outcomes mainly in North America. We established a Japanese version of the MHQ and evaluated its reliability and validity compared with both the short-form 36 (SF-36) questionnaire and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire in a Japanese-speaking population.

Methods: The MHQ was cross-culturally adapted to a Japanese version according to guidelines. Sixty-eight patients with hand conditions were enrolled in this study and answered the MHQ, DASH questionnaire and SF-36 questionnaire. The MHQ was completed again with an interval of one or two weeks. Reproducibility and internal consistency were statistically assessed by the test-retest method and calculating Cronbach's alpha. Spearman's rank correlation was calculated to assess associations between the MHQ and the SF-36 questionnaire as well as the DASH questionnaire.

Results: The intraclass correlation coefficients of MHQ subscales ranged from 0.68 to 0.93. Aesthetics subscale of the left hand showed the lowest intraclass correlation but still a good correlation. Cronbach's alpha values of the MHQ ranged from 0.81 to 0.96 for all subscales. The absolute values of Spearman's rank correlation coefficient between MHQ subscales and DASH function/symptoms scores ranged from 0.49 to 0.82. Spearman's correlation coefficients of the MHQ total score to subscales of the SF-36 questionnaire ranged from 0.42 to 0.68. The strongest correlations were found between work performance of the MHQ and rolephysical of the SF-36 questionnaire.

Conclusions: The Japanese version of the MHQ has adequate instrument properties for assessing hand outcomes compared with the SF-36 questionnaire as well as the DASH questionnaire.