The consistency and reliability of six-strand and four-strand flexor tendon repairs: a comparative porcine cadaveric study

The aim of this study was to compare the consistency and reliability of the six-strand Gan modification of the Lim-Tsai flexor tendon repair with the four-strand Adelaide repair, both with 3-0 sutures and with eight to ten runs of simple 5-0 running peripheral suture as well as the influence of the surgeons’ level of experience on the strength of the repair in a cadaveric animal setup. Thirty-nine surgeons repaired 78 porcine flexor digitorum profundus tendons with either the Adelaide technique (39 tendons) or the modified Lim-Tsai technique (39 tendons). Each repaired tendon was tested in a material testing machine under a single cycle load-to-failure test. The forces were recorded when the gap between the two tendon stumps reached 1 and 2 mm and when irreversible elongation or total rupture occurred. We found no significant differences in gap formation force and yielding strength of the tendons between the two methods. The surgeon’s previous experience in tendon repairs did not improve the consistency, reliability or tensile strength of the repairs. We conclude that if a strong peripheral suture is added, the modified Lim-Tsai repair has the same technical reliability and consistency as the Adelaide repair in term of ultimate loading strength in this test setup.

Automatic analysis of muscular activity in the flexor digitorum superficialis muscles: A fast screening method for rapid eye movement sleep without atonia

Study objectives To identify a fast and reliable method for rapid eye movement (REM) sleep without atonia (RWA) quantification. Methods We analyzed 36 video-polysomnographies (v-PSGs) of isolated REM sleep behavior disorder (iRBD) patients and 35 controls’ v-PSGs. Patients diagnosed with RBD had: i) RWA, quantified with a reference method, i.e. automatic and artifact-corrected 3-s Sleep Innsbruck Barcelona (SINBAR) index in REM sleep periods (RSPs, i.e. manually selected portions of REM sleep); and ii) v-PSG-documented RBD behaviors. We quantified RWA with other (semi)-automated methods requiring less human intervention than the reference one: the indices proposed by the SINBAR group (the 3-s and 30-s phasic flexor digitorum superficialis (FDS), phasic/”any”/tonic mentalis), and the REM atonia, short and long muscle activity indices (in mentalis/submentalis/FDS muscles). They were calculated in whole REM sleep (i.e. REM sleep scored following international guidelines), in RSPs, with and without manual artifact correction. Area under curves (AUC) discriminating iRBD from controls were computed. Using published cut-offs, the indices’ sensitivity and specificity for iRBD identification were calculated. Apnea-hypopnea index in REM sleep (AHIREM) was considered in the analyses. Results RWA indices from FDS muscles alone had the highest AUCs and all of them had 100% sensitivity. Without manual RSP selection and artifact correction, the “30-s phasic FDS” and the “FDS long muscle activity” had the highest specificity (85%) with AHIREM<15/h. RWA indices were less reliable when AHIREM≥15/h. Conclusions If AHIREM<15/h, FDS muscular activity in whole REM sleep and without artifact correction is fast and reliable to rule out RWA.

Associations Between the Size of Individual Plantar Intrinsic and Extrinsic Foot Muscles and Toe Flexor Strength

Background The size of the plantar intrinsic and extrinsic foot muscles has been shown to be associated with toe flexor strength (TFS). Previous studies adopted the size of a limited plantar intrinsic foot muscle or a compartment containing several muscles as an independent variable for TFS. Among the plantar intrinsic and extrinsic foot muscles, therefore, it is unclear which muscle(s) primarily contributes to TFS development. The present study aimed to clarify this subject. Methods In 17 young adult men, a series of anatomical cross-sectional area of individual plantar intrinsic and extrinsic foot muscles was obtained along the foot length and the lower leg length, respectively, using the magnetic resonance imaging. Maximal anatomical cross-sectional area (ACSAmax) and muscle volume (MV) for each constituent muscle of the plantar intrinsic foot muscles (flexor hallucis brevis; flexor digitorum brevis, FDB; abductor hallucis; adductor hallucis oblique head, ADDH-OH; adductor hallucis transverse head, ADDH-TH; abductor digiti minimi; quadratus plantae) and extrinsic foot muscles (flexor hallucis longus; flexor digitorum longus) were measured. TFS was measured with a toe grip dynamometry. Results TFS was significantly associated with the ACSAmax for each of the ADDH-OH (r = 0.674, p = 0.003), ADDH-TH (r = 0.523, p = 0.031), and FDB (r = 0.492, p = 0.045), and the MV of the ADDH-OH (r = 0.582, p = 0.014). As for the ADDH-OH, the correlation coefficient with TFS was not statistically different between ACSAmax and MV (p = 0.189). Stepwise regression analysis indicated that ACSAmax and MV of the ADDH-OH alone explained 42% and 29%, respectively, of the variance in TFS. Conclusion The ADDH-OH is the key muscle that primarily contributes to TFS development among the plantar intrinsic and extrinsic foot muscles.

Ulnar Superficialis Slip Resection versus Radial Superficialis Slip Resection: A Biomechanical Pilot Study

Background: There are numerous clinical scenarios during which the surgeon contemplates whether the radial or ulnar slip of the flexor digitorum superficialis (FDS) should be sacrificed. To date no study has assessed the point of failure of each one of the FDS slips in each digit, aiding the avid surgeon in deciding which slip to sacrifice. Methods: A total of 41 digits were assessed, each digit was dissected, and a specimen containing the denuded bone of the middle phalanx with the attachments of the ulnar and radial FDS slips was obtained. An Instron 4502 device was utilized to biomechanically assess the point of failure of each slip of each digit. Results: There was no statistical difference between ulnar and radial slip point of failure when compared across all digits and subjects. There was no statistical difference between male and female subject’s specimens. The point of failure was higher in the ulnar slips of the second and third digits, whereas the point of failure was higher in the radial slips of the fourth and fifth digits. Conclusions: Sacrifice of a FDS slip may cause loss of grip strength. In several clinical scenarios one may be faced with the dilemma which FDS slip to sacrifice. Our findings show this is not an arbitrary choice. Hand surgeons should keep our findings in mind when deciding which slip to sacrifice, in effort to preserve function and strength in the injured hand.

An Erratic Origin of Quadratus Plantae: An Embryological Error

Background: Quadratus plantae (Flexor digitorum accessorius) is one of the plantar muscles of foot . It is present in the second layer of sole. It takes origin from calcaneus and gets inserted into the tendon of flexor digitorum longus. The main function of it is to flex the lateral four toes in any position of the ankle joint by pulling on tendons of the flexor digitorum longus. Its variations like high origin have been implicated in the causation of tarsal tunnel syndrome. Methodology and Results: In routine dissection done on 22 cadavers, we observed a bilateral variant muscle flexor digitorum accessorius longus on both right and left sides in a male cadaver. The modality of choice in diagnosing the accessory muscle is magnetic resonance imaging. Conclusion: The knowledge of this variation would be essential to anatomists, radiologists and also to the foot surgeons while performing posterior ankle endoscopy. KEY WORDS: Flexor digitorum Accessorius longus, Tarsal tunnel syndrome, Posterior ankle endoscopy.

Influence of the flexor digitorum superficialis tendon transfer on grip strength

The flexor digitorum superficialis tendon of the ring finger can be transferred to the thumb flexor. We followed ten patients after such a transfer for 5–128 months and measured grip strength and force transmission of the fingers and individual phalanges while the patients gripped 10-cm or 20-cm diameter cylinders. The grip strength of the middle, ring and little fingers was reduced when gripping the 10-cm cylinder, with a significantly larger decrease in the ring finger. With the 20-cm cylinder, grip forces of all fingers were almost identical, with slightly lower force of the ring finger and slightly higher forces in the index and small fingers. We conclude that after transfer of flexor digitorum superficialis tendon from a ring finger, grip strength of the ring finger is reduced. Finger forces are more hampered while gripping objects with smaller circumferences than large ones.

Acute Whole-Body Vibration Exercise Promotes Favorable Handgrip Neuromuscular Modifications in Rheumatoid Arthritis: A Cross-Over Randomized Clinical

Objective. Rheumatoid arthritis (RA) causes progressive changes in the musculoskeletal system compromising neuromuscular control especially in the hands. Whole-body vibration (WBV) could be an alternative for the rehabilitation in this population. This study investigated the immediate effect of WBV while in the modified push-up position on neural ratio (NR) in a single session during handgrip strength (HS) in women with stable RA. Methods. Twenty-one women with RA (diagnosis of disease: ±8 years, erythrocyte sedimentation rate: ±24.8, age: 54± 11 years, BMI: 28 ± 4 kg ·m-2) received three experimental interventions for five minutes in a randomized and balanced cross-over order: (1) control—seated with hands at rest, (2) sham—push-up position with hands on the vibration platform that remained disconnected, and (3) vibration—push-up position with hands on the vibration platform turned on (45 Hz, 2 mm, 159.73 m·s-2). At the baseline and immediately after the three experimental interventions, the HS, the electromyographic records (EMGrms), and range of motion (ROM) of the dominant hand were measured. The NR, i.e., the ratio between EMGrms of the flexor digitorum superficialis (FDS) muscle and HS, was also determined. The lower NR represented the greater neuromuscular efficiency (NE). Results. The NR was similar at baseline in the three experimental interventions. Despite the nonsignificance of within-interventions ( p = 0.0611 ) and interaction effect ( p = 0.1907 ), WBV exercise reduced the NR compared with the sham and control ( p = 0.0003 , F = 8.86 , η 2 = 0.85 , power = 1.00 ). Conclusion. Acute WBV exercise under the hands promotes neuromuscular modifications during the handgrip of women with stable RA. Thus, acute WBV exercise may be used as a preparatory exercise for the rehabilitation of the hands in this population. This trial is registered with trial registration 2.544.850 (ReBEC-RBR-2n932c).

Novel Ultrasonographic Thickness and Strength Assessments of the Flexor Digitorum: A Reliability Analysis

OBJECTIVES: Clinical conditions such as focal dystonia often require the assessment of atrophy and weakness of the finger muscles. However, due to a lack of well-established protocols, the current investigation focused on assessing the reliability of thickness and strength assessments of the flexor digitorum (FD) muscle, including both the superficialis and profundus components. As a secondary assessment, the reliability of the strength measurement of the extensor digitorum muscle was examined as well. METHODS: Different thickness measurements of the FD were taken via ultrasonography and averaged to estimate the mean thickness of the FD. Likewise, individual finger strength measurements taken by a custom-made finger pressure device were averaged to compute the mean strength of the flexor and extensor digitorum muscles. Test-retest reliability of the above measurements performed at two different time points (about 6 months apart) were examined on the right and left hands of 10 participants. RESULTS: Findings indicated excellent test-retest reliability (ICC > 0.92) for the mean thickness assessment of the FD and mean strength of the flexor and extensor digitorum for both dominant and non-dominant hands. The standard error of measurement was ≤4.3% for all three mean assessments, indicating high sensitivity. Likewise, the smallest detectable change was also sufficiently small for the mean thickness and mean strength of the flexor digitorum (≤5.1%) and moderately small (≤12%) for the strength of the extensor digitorum. CONCLUSIONS: Results indicated an excellent relative and absolute reliability, for both hands, for the mean thickness and strength assessments of the flexor digitorum muscle and for the mean strength of the extensor digitorum (measured for both hands). These measurements can be used for future investigations and can contribute to the establishment of more precise methods for assessing the muscles in the forearms which serve the hand.