Skeletal anatomy of the hand

Preliminary study on hand dimensions as potential predictors of female populations native to forest and savanna zones in Ghana

The hand is a versatile structure that performs numerous tasks, ranging from exertion of great force such as grip, pinch and torque to execution of precise fine motor skills. The aim of current study was to undertake a preliminary study on hand dimensions as potential predictors of female populations native to the forest and savanna zones of Ghana. A total of one hundred (100) female students aged between 17 and 24 years were recruited into this study, comprising of 53 native to the forest zone and 47 native to savanna zone of Ghana between 12th June to 27th July, 2023 at the Department of Anatomy, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology. Statistically significant positive correlation was observed between left hand length and right hand length (R = 0.923, p = 0.000). From the binary regression model, it could be speculated that left-hand breadth could predict female populations native to the savanna zone (LHB: β = - 2.37, Expβ = 0.09, p = 0.014). However, right-hand breadth and length and left hand length did not show any potential of prediction (RHB: β = 0.900, Expβ = 2.460, p = 0.410; RHL: β = 0.168, Expβ = 1.683, p = 0.803; LHL: β = - 0.300, Expβ = 0.741, p = 0.656). The study therefore may speculate that left handbreadth could have the potential to differentiate female populations native to savanna zone from females native to forest zone in Ghana.

Advancements in Metacarpal Fracture Management: A Narrative Review of Rehabilitative Strategies

Metacarpal fractures are prevalent injuries that can significantly impact hand functionality if not managed effectively. This narrative review examines recent advancements in treatment strategies, comparing conservative and surgical interventions, and evaluates the role of early mobilization and innovative rehabilitation techniques. We analyze evidence showing that surgical treatment with low-profile titanium plates provides superior stabilization, enabling earlier mobilization and better functional outcomes compared to conservative methods or K-wire fixation. Early mobilization, facilitated by metacarpal braces or controlled active exercises, enhances recovery and reduces the need for extended physical therapy. We also explore the integration of technology in rehabilitation, which has improved patient adherence and satisfaction. The review highlights the importance of personalized treatment plans and discusses the potential of novel rehabilitation approaches to optimize metacarpal fracture management. Future research should focus on refining these strategies and developing standardized protocols to enhance hand function and patient satisfaction.

The Volar Midline Longitudinal Groove of the Middle Phalanx: An Anatomic Study and Clinical Implications

PURPOSE

To investigate the volar anatomy of the middle phalanges of the hand; in particular, to define the presence and depth of a volar midline longitudinal groove.

METHODS

Measurements were performed at 5 equidistant points along the shafts of 60 skeletonized middle phalanges from 15 cadaveric hands. The thickness at the midline of each phalanx was subtracted from the maximal dorsovolar thickness to indicate the presence or absence of a groove at each point. The phalanges were also evaluated by computed tomography to confirm the presence of a volar groove and to rule out morphological abnormalities.

RESULTS

A volar groove was confirmed in all 60 phalanges. The groove had an average depth of 0.4 mm and was found to be deepest at the mid-phalangeal shaft. The groove reached a depth of greater than 1 mm in 23% of the phalanges. The middle phalanges of the middle and ring digits consistently revealed deeper grooves than those found in the index and little fingers. Computed tomography confirmed the presence of a volar groove and showed no morphological abnormalities.

CONCLUSIONS

A midline volar longitudinal groove is present in the middle phalanges, is most pronounced in the mid-phalangeal shaft, and is the deepest in the middle and ring fingers.

CLINICAL RELEVANCE

Surgeons should be cognizant of the volar longitudinal groove when inserting screws from dorsal to volar during the fixation of middle phalangeal fractures. Lateral intraoperative fluoroscopy may not reveal excessive screw penetration because of the presence of ridges on either side of the groove. Particular care should be taken at the mid-phalangeal level of the middle phalanges of the middle and ring fingers.

Assessment of Bone Age Based on Hand Radiographs Using Regression-Based Multi-Modal Deep Learning

(1) Objective: In this study, a regression-based multi-modal deep learning model was developed for use in bone age assessment (BAA) utilizing hand radiographic images and clinical data, including patient gender and chronological age, as input data. (2) Methods: A dataset of hand radiographic images from 2974 pediatric patients was used to develop a regression-based multi-modal BAA model. This model integrates hand radiographs using EfficientNetV2S convolutional neural networks (CNNs) and clinical data (gender and chronological age) processed by a simple deep neural network (DNN). This approach enhances the model's robustness and diagnostic precision, addressing challenges related to imbalanced data distribution and limited sample sizes. (3) Results: The model exhibited good performance on BAA, with an overall mean absolute error (MAE) of 0.410, root mean square error (RMSE) of 0.637, and accuracy of 91.1%. Subgroup analysis revealed higher accuracy in females ≤ 11 years (MAE: 0.267, RMSE: 0.453, accuracy: 95.0%) and >11 years (MAE: 0.402, RMSE: 0.634, accuracy 92.4%) compared to males ≤ 13 years (MAE: 0.665, RMSE: 0.912, accuracy: 79.7%) and >13 years (MAE: 0.647, RMSE: 1.302, accuracy: 84.6%). (4) Conclusion: This model showed a generally good performance on BAA, showing a better performance in female pediatrics compared to male pediatrics and an especially robust performance in female pediatrics ≤ 11 years.

Using a Sensor-Embedded Baseball to Identify Finger Characteristics Related to Spin Rate and Pitching Velocity in Pitchers

BACKGROUND

Previous investigations have shown a positive relationship between baseball pitching velocity and the kinetic chain involved in pitching motion. However, no study has examined the influence of finger characteristics on pitching velocity and rate of spin via a sensor-embedded baseball.

METHODS

Twenty-one pitchers volunteered and were recruited for this study. An experimental baseball embedded with a force sensor and an inertial measurement unit was designed for pitching performance measurement. Finger length and strength were measured as dependent variables. Spin rate and velocity were independent variables. Pearson product-moment correlations (r) and intraclass correlation coefficients (ICCs) determined the relationship between finger characteristics and pitching performance.

RESULTS

Finger length discrepancy, two-point pinch strength, index finger RFD (rate of force development), middle finger impulse, and force discrepancy had significant correlations with spin rate (r = 0.500~0.576, p ≤ 0.05). Finger length discrepancy, two-point pinch, three-point pinch strength, index and middle finger RFD, middle finger impulse, and force combination had significant correlations with fastball pitching velocity (r = 0.491~0.584, p ≤ 0.05).

CONCLUSIONS

Finger length discrepancy, finger pinch strength, and pitching finger force including maximal force and RFD may be factors that impact fastball spin rate and fastball pitching velocity.

Exploring Age-Related Variations in Carpal Bone Volume: Implications for Clinical Practice and Anatomical Understanding

BACKGROUND

Clinically recognizing the changes in carpal bone volumes and understanding their implications in predicting osteoarthritis (OA) is crucial in clinical practice This study aimed to explore age-related differences in carpal bone volumes across genders, leveraging computed tomography (CT) wrist scans to create 3D surface models of these bones.

METHODS

Carpal bone volumes were calculated using the 3D Slicer software from CT scans obtained from Frankston Hospital and additional datasets from Brown and Auckland Universities. The data were statistically processed using Stata V13. Double-sided P-values < .05 were considered statistically significant. The study was conducted in accordance with the ethical standards laid out in the Declaration of Helsinki.

RESULTS

A total of 181 patients were analyzed, and 48% of whom were female. A statistically significant positive Spearman correlation (rho = 0.37-0.611, P <.05) was observed between increasing age and the volume of all surveyed carpal bones (scaphoid, lunate, triquetrum, pisiform, hamate, capitate, and trapezium) across genders. Intrauser and interuser reliabilities for 3D Slicer-generated volumes of trapezium and pisiform bones were statistically significant, with Interclass Correlation Coefficient (ICC) values of 0.86 and 0.95, respectively.

CONCLUSION

Trapezial volumes increase with age, potentially due to the presence of OA and consequent osteophyte formation. This pattern is more prevalent among older individuals and women. However, the positive correlation between carpal bone volume and age was consistent across all carpal bones and both genders, regardless of OA presence. These findings suggest that carpal bone volume may naturally increase with age, independent of OA-related changes.

LEVEL OF EVIDENCE

III, cohort study.

Surgical anatomy of the nail

Knowledge of nail anatomy is a prerequisite for both diagnostic and therapeutic purposes. The nail apparatus is a highly specialized structure, but is in close relationship to the distal phalanx which supports it and to the pulp which carries the sensory receptors and is involved in pinching. It can be divided by the nail plate into the perionychium underneath, and the paronychium above. The perionychium includes, from proximal to distal: the nail matrix, the sole structure responsible for the growth of the nail plate; the nail bed, mostly responsible for adhesion of the plate; and the hyponychium, which is the most distal part, where the nail plate loses its adhesion. The paronychium comprises three nail folds, one proximal and two lateral, that embed the nail plate. The nail apparatus is richly vascularized, with three main sources, and richly innervated, which explains why trauma and surgery are so painful.

Machine-learned wearable sensors for real-time hand-motion recognition: toward practical applications

Soft electromechanical sensors have led to a new paradigm of electronic devices for novel motion-based wearable applications in our daily lives. However, the vast amount of random and unidentified signals generated by complex body motions has hindered the precise recognition and practical application of this technology. Recent advancements in artificial-intelligence technology have enabled significant strides in extracting features from massive and intricate data sets, thereby presenting a breakthrough in utilizing wearable sensors for practical applications. Beyond traditional machine-learning techniques for classifying simple gestures, advanced machine-learning algorithms have been developed to handle more complex and nuanced motion-based tasks with restricted training data sets. Machine-learning techniques have improved the ability to perceive, and thus machine-learned wearable soft sensors have enabled accurate and rapid human-gesture recognition, providing real-time feedback to users. This forms a crucial component of future wearable electronics, contributing to a robust human-machine interface. In this review, we provide a comprehensive summary covering materials, structures and machine-learning algorithms for hand-gesture recognition and possible practical applications through machine-learned wearable electromechanical sensors.

Non-surgical treatment of oblique diaphyseal fractures of the fourth and fifth metacarpals in a professional athlete: A case report

INTRODUCTION

Metacarpal fractures are common sports-related injuries, often requiring tailored treatment strategies, especially in athletes. The management of oblique diaphyseal fractures poses unique challenges due to their inherent instability. This case report discusses a non-surgical approach in treating such fractures in a professional athlete.

CASE PRESENTATION

A 26-year-old professional soccer player sustained oblique diaphyseal fractures of the fourth and fifth metacarpals during training. Given the athlete's professional demands and the fracture's nature, a conservative treatment was implemented. This included the application of a modified ulnar gutter brace, allowing for immobilization of the metacarpophalangeal joints (MP) while permitting active mobilization of the interphalangeal joints(IP).

CLINICAL DISCUSSION

The non-surgical treatment focused on achieving skeletal stability and maintaining hand function. Despite the complexity of oblique fractures, the conservative approach was successful, enabling the athlete to resume professional activities with minimal risk of fracture displacement. Regular radiographic follow-ups showed no further displacement, highlighting the effective management of such fractures through personalized conservative treatment plans.

CONCLUSIONS

This case underscores the viability of conservative treatment for specific metacarpal fractures in athletes. Tailoring the treatment to accommodate the athlete's professional needs and understanding the biomechanical characteristics of the fracture are crucial for successful outcomes. The case also suggests that non-surgical management can be a viable option for certain complex metacarpal fractures, especially in high-demand patients.

Proximal Interphalangeal Joint Fractures: Various Approaches to Fixation

There are numerous operative and nonoperative options for the management of proximal interphalangeal joint fractures and fracture dislocations. The treatment of choice should be guided by the fracture pattern and joint stability. The authors highlight a contemporary option for open reduction and internal fixation techniques, but all the techniques presented are viable options under the right circumstances. It is also important to set patient expectations as most of these patients will note post-injury stiffness and potential functional limitations.

Surgical Technique: Lateral Plate Osteosynthesis of Proximal Phalanx Fractures

Dorsal plate fixation of proximal phalanx (PP) fractures is a conventional approach but interferes with the extensor mechanism and results in stiffness. Biomechanical studies have shown that laterally placed plates on the proximal phalanges are equally stable and rigid. This technique obviates the issue of tendon adhesion and may result in better postoperative range of motion and lower secondary procedures such as removal of implant and tenolysis. The low adoption of this technique may be related to lack of familiarity with the surgical approach. We describe our surgical technique with lateral plating of PP fractures and present our case that lateral plate osteosynthesis is an acceptable surgical fixation option for PP fractures, which extends the hand surgeon's armamentarium for more challenging and comminuted fractures.

Ring finger metacarpal fracture iatrogenic rotation using an ulnar gutter splint: A cadaveric study

STUDY DESIGN

Cohort cadaveric study.

INTRODUCTION

Ring finger metacarpal fractures are often treated with ulnar gutter orthoses incorporating the ring and small fingers. Iatrogenic pronation of the distal metacarpal fragment may occur from overzealous orthotic "molding", resulting in a crossover deformity of the ring finger over the small finger.

PURPOSE OF THE STUDY

The goal of this cadaveric study is to determine whether including the middle finger in an ulnar gutter orthotic could lessen the chances of iatrogenic ring finger metacarpal fracture rotation.

METHODS

Transverse ring finger metacarpal shaft fractures were created in 24 cadaver hands. The ring and small fingers were then placed into an intrinsic plus position, simulating the application of an ulnar gutter orthotic. Weights of 2.5, 5, and 10 pounds were applied to the ring and small fingers to simulate iatrogenic-induced fracture pronation. The amount of rotational displacement at the fracture was measured, and the protocol was repeated, including the middle finger in the intrinsic plus position. Mann-Whitney-Wilcoxon test was used for statistical analysis.

RESULTS

There was an increase in distal fragment rotation with increasing weight. Fracture displacement was greater with the 2-finger position than the 3-finger at all weight levels; this reached statistical significance at 10 lbs (2.8 vs 1.8 mm).

CONCLUSIONS

Application of an ulnar gutter orthotic including only ring and small fingers can rotate the distal fragment of a ring finger metacarpal shaft fracture such that overlap could occur with the small finger. Including the middle finger in ulnar gutter splints will mitigate against the rotation of the ring finger metacarpal shaft fracture.

Anatomy and Biomechanics of the Thumb Carpometacarpal Joint

This review discusses the anatomy and biomechanics of the thumb carpometacarpal (CMC) joint. This articulation between the trapezium and first metacarpal is integral for opposition and other complex movements necessary for pinch and grasp maneuvers. Fortunately, this joint is well equipped to handle the extreme forces imposed by these movements, as it is stabilized by an elaborate arrangement of ligaments and muscles. Without this stability, thumb subluxation would occur with loading during pinch and grasp, and human prehension would be impossible. Understanding the interactions occurring within this joint is essential for adequately treating pathology arising in this crucial joint.

Conservative management equally effective to new suture anchor technique for acute mallet finger deformity: A prospective randomized clinical trial

STUDY DESIGN

Prospective randomized controlled trial.

PURPOSE OF THE STUDY

This study was designed to compare our new suture anchor technique with conservative management in acute Wehbe-Schneider type I A-B and II A-B mallet fingers.

METHODS

Twenty nine patients who presented to our clinic between 2013 and 2015 were randomized for surgical or conservative treatment. Wehbe-Schneider subtype C fractures were excluded. Fourteen were treated with surgery, and 15 were treated with conservative treatment. Primary outcomes were visual analog scale score, active distal interphalangeal (DIP) joint flexion, return to work, extension deficit and DIP joint degeneration. Follow-up time was 12 months.

RESULTS

The mean visual analog scale was 2.0, and return to work was on average in 63.2 days in the surgical group and 1.47 and 53.7 days in the conservative group. Extension deficit was 8.1° in the surgical group and 6.1° in the conservative group. The mean DIP flexion at final follow-up was 54.5° (40-65) in the surgery group and 58.3° (45-70) in the conservative group. DIP joint degeneration was observed with X-rays in 4 patients in surgical group, and none of the patients in the conservative group had DIP degeneration at 1 year after treatment.

CONCLUSIONS

The therapeutic effectiveness of suture anchor technique was not statistically different from conservative treatment. Subluxation seen after fixation treatment with suture anchors may be due to inadequate anchor fixation. DIP joint degeneration was seen significantly more in the surgical group. Our study suggests that the new suture anchor technique is not superior to conservative treatment.

LEVEL OF EVIDENCE

Ib.

Bony anatomy of the third metacarpal and relationship with the capitate: a computed tomography study

PURPOSE

The purpose of this study was to accurately establish the anatomical variability of the third metacarpal, its medullary canal, and the relationship with the capitate in the context of high rates of component loosening still seen in total wrist arthroplasty.

METHODS

CT scans of a 100 hands (age: 41 ± 14 years (range: 16-71 years); male/female ratio: 53/47) were studied to establish the detailed anatomy of the third metacarpal and the capitate.

RESULTS

Although the shape of the third metacarpal and the angles formed with the capitate were highly variable, the third metacarpal length was longer in males (p < 0.001), the proximal cortical bone was thicker (p < 0.001) and the sagittal metacarpal-capitate axis offset was greater (p = 0.01). A relationship was found between the total length of the metacarpal and the distance to the isthmus from the base (r = 0.63; p < 0.0001) which was unaffected by gender. No age-related relationships were significant.

CONCLUSION

The anatomy of the third metacarpal and capitate varies considerably more than has been alluded to in current wrist arthroplasty literature. Differences between males and females can likely be attributed to hand size. The distance of the isthmus from the base can be predicted from the total length of the metacarpal with a standard error of 1.9 mm.

Thumb Injuries in Athletes

Thumb injuries are common in athletes and present a challenging opportunity for upper extremity physicians. Common injuries include metacarpal base fractures (Bennett and Rolando types), ulnar and radial collateral ligament injuries, dislocation of the carpometacarpal and metacarpophalangeal joints, and phalanx fractures. This review, although not exhaustive, highlights some of the most common thumb injuries in athletes. The treating physician must balance pressure from athletes, parents, coaches, and executives to expedite return to play with the long-term well-being of the athlete. Operative treatment may expedite return to play; however, one must carefully weigh the added risks involved with surgical intervention.