OBJECTIVE: The purpose of this study was to compare clinical and radiologic outcomes of biological ligament reconstruction (BLR) versus nonbiological ligament reconstruction (NBLR) for chronic injuries involving the ulnar collateral ligament of the thumb\'s metacarpophalangeal joint.
METHODS: Forty-two patients who underwent static BLR (n = 24) or NBLR (n = 18) were included in this retrospective analysis. Preoperative, postoperative, and contralateral thumb measurements (clinical evaluation, radiographs, and subjective outcome questionnaires) were compared over a mean of 38 months of follow-up.
RESULTS: Average postoperative thumb metacarpophalangeal and interphalangeal joint ranges of motion were 2° to 54° and 0 to 71°, respectively, for BLR and 0° to 58° and 0° to 71°, respectively, for NBLR. Average grip and pinch strengths, relative to the unaffected hand, were 102% and 84% versus 103% and 89%, respectively. All patients demonstrated stability with a firm end point, compared with the unaffected thumb. The average Quick Disabilities of the Arm, Shoulder, and Hand score among all patients was 12 for the disability/symptom module, 0 for the sports module, and 17 for the work module. Stiffness was reported among four patients, and no patient sustained wound-related issues or other complications.
CONCLUSIONS: Nonbiological ligament reconstruction of the thumb ulnar collateral ligament generates short-term outcomes comparable with those of BLR, potentially allowing for expedited recovery and rehabilitation.
METHODS: Therapeutic IV.

OBJECTIVE: The position of sesamoid of thumb metacarpophalangeal (MCP) joint changed clearly when the joint was dislocated dorsally. However, the significance of sesamoid location in diagnosing joint dislocation was unclear. The present study aimed to explore the positional relationship between sesamoid bone and thumb metacarpophalangeal joint in normal and dorsal dislocation joints.
METHODS: Between January 2018 and August 2023, we collected 60 isometric plain films from sixty outpatients and reviewed 56 anisometric plain films from twenty-eight emergency patients with dorsal dislocation of thumb MCP joint at Tianjin Hospital, then took measurements on the hand X-ray images. The sesamoid length on its longitudinal axis was defined as DP, the distance between the distal edge of sesamoid and thumb MCP joint was defined as DJ, and the ratio of DJ and DP was R. An independent-samples t-test and paired-samples t-test was utilized to analyze difference among data groups.
RESULTS: The 60 isometric images were from 30 male and 30 female outpatients with normal bone structure in their hands, and the 56 anisometric images of the 28 emergency patients included both preoperative and postoperative materials. Among the outpatients, the actual distance between the distal edge of sesamoid and thumb MCP joint space (DJ) was 2.09 mm and 1.40 mm in males and females, respectively. The authentic average length of sesamoid (DP) was 4.46 mm in males and 4.22 mm in females. The average value of R (the ratio of DJ and DP) in males and females was 0.49 and 0.34, respectively. There were gender-related statistical differences in DJ (p < 0.01) and R (p=0.01), but no statistical difference in DP (p > 0.05). For the 28 emergency patients, the mean value of R was -0.47 before joint reduction and 0.58 after joint reduction, with statistical difference between them (p < 0.01).
CONCLUSIONS: There was significant difference in the relative position between sesamoid and thumb MCP joint when joint dislocation and joint reduction. The distal edge of sesamoid beyond thumb MCP joint could be an evidence in diagnosing joint dorsal dislocation. The distal edge of sesamoid below thumb MCP joint could be an evidence of joint reduction.

To compare the efficacy of a traditional cock-up splint, which supports the wrist only, with a modified splint that supports the wrist and the metacarpophalangeal (MCP) joints of the medial four digits in the treatment of carpal tunnel syndrome (CTS).
An assessor-blind randomised controlled trial.
Hospital-based hand therapy clinics.
Fifty-nine adults with mild-to-moderate CTS were randomly assigned to wear a wrist splint (control group) or an MCP splint (intervention group) for 6 weeks.
The standardised outcome measures used included grip and pinch strength, the static two-point discrimination test, Phalen\'s manoeuvre test, Tinel\'s sign and the Boston CTS Questionnaire.
Both groups improved significantly from splint use in some clinical features. The wrist splint and the MCP splint groups had significant improvements in lateral pinch strength (p=0.032 and p=0.002, respectively), two-point discrimination of the thumb (p=0.003 and p=0.041, respectively), two-point discrimination of the index (p=0.035 and p=0.023, respectively) and the Phalen\'s manoeuvre symptoms (p=0.025 and p=0.002, respectively). The MCP splint group had additional improvements over the wrist splint group in tip pinch (p=0.012) and Palmar pinch (p=0.011) strength.
Splinting is a practical and effective intervention option for improving the symptoms of CTS. A wrist splint that incorporates the MCP joints is more effective than the traditional wrist-only splint, with long-lasting improvements that remained consistent after 6 months of the splint intervention. Using the more effective MCP splint may consequently reduce disability, facilitate return to work and lower the associated costs.
ISRCTN13189602.

Several studies have indicated that Camitz transfer for severe carpal tunnel does not adequately restore thumb opposition. The aim of this study was to determine whether modification of the distal insertion of the transferred palmaris longus tendon could provide more effective opposition. We used 12 fresh-frozen upper extremity specimens. For spatial analysis, we used a three-dimensional motion-tracking device. At 0 N and 5 N of traction force, the pronation angle was significantly larger for the modified procedure than for the conventional procedure. There was no significant difference in the palmar abduction angle between the two groups. The modified palmaris longus tendon insertion on the ulnar side of the thumb metacarpophalangeal joint provides more effective thumb pronation than conventional Camitz opponensplasty in a cadaver model.    .

OBJECTIVE: The aim of this study was to calculate the stress acting on the trapeziometacarpal joint during an key pinch grip.
METHODS: We used profile X-rays of the thumb to measure the various bony and muscle lever arms. We assessed the angles of action of the muscular elements involved in the thumb column. Based on this data, we established a two-dimensional geometric model that enabled us to determine the forces at each joint level, as a function of stresses and muscular contributions. We were also able to calculate the participation of the different muscle groups in obtaining a balanced situation.
RESULTS: Our results, as a function of the degree of flexion of the interphalangeal and metacarpophalangeal joints, show a multiplying factor of 2.9-3.19 in relation to the key pinch grip force.
CONCLUSIONS: Previous studies modelling a key pinch grip are showed multiplying factors from 6 to 13 in relation to the key pinch grip force. They are not compatible with the characteristics of the polyethylene used for trapeziometacarpal prostheses, whereas numerous articles in the literature show survival rates that are more or less comparable to those of total hip prostheses. These studies required an excessive number of assumptions, which could lead to error. Our results are compatible with the results of trapeziometacarpal prosthesis and with those of a recent study measuring intra-articular trapeziometacarpal pressure in a cadaveric model. Our model allows us to test different configurations of the thumb spine depending on the degree of flexion of the interphalangeal and metacarpophalangeal joints.

OBJECTIVE: Ni-Ti memory alloys are unusual materials for hard-tissue replacement because of their unique superelasticity, good biocompatibility, high strength, low specific gravity, low magnetism, wear resistance, corrosion resistance and fatigue resistance. The current study aims to evaluate its mechanical properties and provide biomechanical basis for the clinical application of the prosthesis.
METHODS: Ten adult metacarpophalangeal joint specimens were randomly divided into a prosthesis group (n = 5, underwent metacarpophalangeal joint prosthesis) and a control group (n = 5, underwent sham operation). Firstly, the axial compression strength was tested with BOSE material testing machine to evaluate its biomechanical strength. Secondly, these specimens were tested for strain changes using BOSE material testing machine and GOM non-contact optical strain measurement system to evaluate the stress changes. Thirdly, fatigue test was performed between groups. Lastly, the mechanical wear of the metacarpophalangeal joint prosthesis was tested with ETK5510 material testing machine to study its mechanical properties.
RESULTS: Axial compression stiffness in the prosthesis group was greater than that in the control group in terms of 30 ° and 60 ° flexion positions (P < 0.05). There was no statistically significant difference between two groups with regards to axial compression stiffness and stress change test (P > 0.05). In the fatigue wear test, the mean mass loss in the prosthesis group\'s prosthesis was 17.2 mg and 17.619 mm3, respectively. The mean volume wear rate was 0.12%. There was no statistically significant difference in the maximum pull-out force of the metacarpal, phalangeal, and polymer polyethylene pads between the prosthesis group and the control group specimens.
CONCLUSIONS: Ni-Ti memory alloy metacarpophalangeal joint prosthesis conforms to the biomechanical characteristics of metacarpophalangeal joints without implants, and the fatigue strength can fully meet the needs of metacarpophalangeal joint activities after joint replacement.

To investigate the relationship between disease-related parameters and joint space width (JSW) on high-resolution peripheral quantitative computed tomography (HR-pQCT) in psoriatic arthritis (PsA) patients.
PsA patients who underwent HR-pQCT examination of the second to fourth metacarpophalangeal joint (MCPJ 2-4) were recruited in this cross-sectional study. The joint space metrics included joint space volume (JSV), mean, minimum, and maximum JSW, JSW asymmetry, and distribution. Correlation analysis and multivariable linear regression models were used to determine the association between disease-related variables and JSW.
Sixty-seven patients [37 (55.2%) males; median (IQR) age: 57.0 (53.0, 63.0); median disease duration: 21 (16, 28) years] were included in this analysis. Multivariable linear regression analysis demonstrated that males had larger JSV (MCPJ 2-4), mean (MCPJ 4), and maximum JSW (MCPJ 3). Longer disease duration (MCPJ 2-3) and higher ESR values (MCPJ 3) were negatively associated with mean and maximum JSW, while higher damage joint count was negatively associated with mean and minimum JSW (MCPJ 2). Use of conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) was negatively associated with minimum JSW (MCPJ 3) while use of biologic DMARDs (bDMARDs) was positively associated with minimum JSW (MCPJ 2).
Higher inflammatory burden as reflected by longer disease duration, higher ESR levels, and damage joint count was negatively associated with mean, maximum, and minimum JSW, while suppression of inflammation using bDMARDs seems to limit the decline in JSW.

Mean metacarpophalangeal joint angles of the thumb during maximal pinch were 9° greater in men than in women. More flexion was not associated with more force during key pinch, but a moderate association was found for palmar pinch, especially in men.

OBJECTIVE: Exhaustive literature is available on the metacarpophalangeal joints of the long fingers, but the dorsal ligamentous structure overlaying the interosseous muscles and joining the metacarpal heads of the long fingers remains to be fully characterized. Previously, our surgical hand team observed a non-classically reported structure connecting the metacarpal heads of the long fingers, in the dorsal part of the intermetacarpal spaces. Therefore, the aim of this anatomical study was to characterize this ligamentous structure in terms of size, insertions, and anatomical position.
METHODS: Twenty-five hands were dissected for a total of 75 long finger intermetacarpal spaces. A ligamentous structure was exposed after cellular tissue excision and dorsal superficial fascia opening. The length and thickness were measured and anatomical position and insertions were studied. Histological analysis was performed on five specimens and ultrasound analysis in one healthy subject.
RESULTS: All 25 dissections revealed a dorsal ligamentous structure, hereafter named distal dorsal intermetacarpal ligament, which was inserted in the lateral tubercle of each adjacent long finger metacarpal head. This distal dorsal intermetacarpal ligament surrounded interosseous tendons. It was more proximal compared to oblique and transversal interosseous muscle fibers. Histological analysis confirmed the ligamentous nature of the structure. Ultrasound analysis showed that this structure was well identified under the dorsal aspect of the hand.
CONCLUSIONS: All dissections revealed a tense ligamentous structure between each metacarpal head of the long fingers. This was a constant structure meeting the definition of a ligament. The distal dorsal intermetacarpal ligament seems to stabilize the metacarpal heads at the second and fourth spaces by limiting hyperabduction.

We report a series of 95 consecutive patients operated on for total trapeziometacarpal joint replacement, screening for radiological characteristics to differentiating patients with and without preoperative MCP hyperextension. Loss of thumb column length and metacarpal head circularity on lateral view were quantified. Statistically, a combination of reduced length and circular metacarpal head was a determining factor for MCP hyperextension. We therefore believe it is essential to restore thumb column length in surgery for trapeziometacarpal osteoarthritis and to avoid trapeziectomy in patients with a circular head on lateral view. LEVEL OF EVIDENCE: III; prospective cohort study.